Table of contents

The conference "Climate Change: Causes, Risks, Consequences, Problems of Adaptation and Management" was held in Moscow in November 2019. The results of various areas of climate research were presented at the conference, including the diagnosis of modern climate change based on observational data, reanalysis and paleoreconstructions; modeling of current and future climate change; risk assessment of extreme climatic events; determination of the relative role of natural and anthropogenic factors in climate change; studies of the socio-economic consequences of climate change and adaptation to them. The conference was attended by 214 participants from 46 organizations of the Russian Academy of Sciences, Roshydromet, universities and others. 72 oral reports were presented, including 15 invited talks, and 86 poster presentations.

List of titles 1. Diagnosis of modern climate changes based on observational data, reanalysis, and paleoreconstructions. 2. Modeling of modern and future climate change. 3. The risk of extreme climatic events. 4. The relative role of natural and anthropogenic factors in climate change. 5. Socio-economic consequences of climate change and adaptation to them are available in this pdf.

NOTITLE. Chairman

Mokhov Igor

RAS academecian, Dr. Sci., Professor

A. M. Obukhov Institute of Atmospheric Physics RAS, Moscow

Deputies

Golitsyn Georgii

RAS academecian, Dr. Sci., Professor

Obukhov Institute of Atmospheric Physics RAS, Moscow

Makosco Alexander

RAS corresponding member, Dr. Sci.

Obukhov Institute of Atmospheric Physics RAS, Moscow

Members

Alexeev Genrich

Dr. Sci

Arctic and Antarctic Research Institute, Saint-Petersburg

Vilfand Roman

Dr. Sci

Hydrometeorological Research Center of Russian Federation, Moscow

Volodin Eugeniy

Dr. Sci, RAS professor

Marchuk Institute for numerical mathematics RAS, Moscow

Gelfan Alexander

RAS corresponding member, Dr. Sci.

Water Problems Institute RAS, Moscow

Gulev Sergey

RAS corresponding member, Dr. Sci.

Shirshov Institute of Oceanology, Moscow

Elanskiy Nikolay

RAS corresponding member, Dr. Sci.

Obukhov Institute of Atmospheric Physics RAS, Moscow

Eliseev Alexey

Dr. Sci, RAS professor

Lomonosov Moscow State University, Moscow

Kattsov Vladimir

∂.ф.-M. H.

Voeikov Main Geophysical Observatory, Saint-Petersburg

Kislov Alexander

Dr. Sci, Professor

Lomonosov Moscow State University, Moscow

Krutikov Alexander

Dr. Sci

Institute of Monitoring of Climatic and Ecological Systems SB RAS, Tomsk

Kulichkov Sergei

Dr. Sci.

Obukhov Institute of Atmospheric Physics RAS, Moscow

Lykossov Vasiliy

RAS corresponding member, Dr. Sci

Lomonosov Moscow State University, Moscow

Mareev Eugeniy

RAS corresponding member, Dr. Sci.

Institute of Applied Physics RAS, Nizhniy Novgorod

Panchenko Mikhail

Dr. Sci

Zuev Institute of Atmopsheric Optics SB RAS, Tomsk

Porfiriev Boris

RAS academecian, Dr. Sci.

Institute of Economic Forecasting RAS, Moscow

Revich Boris

Dr. Sci.

Institute of Economic Forecasting RAS, Moscow

Romanovskaya Anna

RAS corresponding member, Dr. Sci.

Izrael Institute of Global Climate and Ecology, Moscow

Semenov Vladimir

RAS corresponding member, Dr. Sci.

Obukhov Institute of Atmospheric Physics RAS, Moscow

Semenov Sergei

Dr. Sci.

Izrael Institute of Global Climate and Ecology, Moscow

Solomina Olga

RAS corresponding member, Dr. Sci.

Institute of Geography RAS, Moscow

Chernokulsky Alexander

PhD

Obukhov Institute of Atmospheric Physics RAS, Moscow

CLIMATE-2019 Organizing committee

Chairman

Mokhov Igor

RAS academecian, Dr. Sci., Professor, A. M. Obukhov Institute of Atmospheric Physics RAS, Moscow

Deputy

Chernokulsky Alexander

PhD, Obukhov Institute of Atmospheric Physics RAS, Moscow

Members

Artamonov Arseniy

Obukhov Institute of Atmospheric Physics RAS, Moscow

Eliseev Alexey

Dr. Sci, RAS professor, Lomonosov Moscow State University, Moscow

Koval Oksana

Obukhov Institute of Atmospheric Physics RAS, Moscow

Pankratova Natalia

PhD, Obukhov Institute of Atmospheric Physics RAS, Moscow

Parfenova Maria

Obukhov Institute of Atmospheric Physics RAS, Moscow

Repina Irina

Dr. Sci, RAS professor, Obukhov Institute of Atmospheric Physics RAS, Moscow

Semenov Vladimir

RAS corresponding memeber, Dr. Sci., A. M. Obukhov Institute of Atmospheric Physics RAS

Moscow

Skorokhod Andrei

PhD, Obukhov Institute of Atmospheric Physics RAS, Moscow

Falaleeva Victoria

Obukhov Institute of Atmospheric Physics RAS, Moscow

Fedorova Evgeniya

Obukhov Institute of Atmospheric Physics RAS, Moscow

Chkhetiani Otto

Dr. Sci, Obukhov Institute of Atmospheric Physics RAS, Moscow

All papers published in this volume of IOP Conference Series: Earth and Environmental Science have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Single-blind

• Conference submission management system: By e-mail - : climate2019@ifaran.ru. The article was sent to the specified email address, the expert board made a decision on the selection of reviewers (two reviewers per article) and sent them a request. Re-peer review was carried out if necessary. After completion of the review process, the expert board made a decision on the acceptance or rejection of the article.

• Number of submissions received: 83

• Number of submissions sent for review: 83

• Number of submissions accepted: 70

• Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100): 82

• Average number of reviews per paper: 2

• Total number of reviewers involved: 171

• Any additional info on review process:

First of all, the correspondence of the article to the topic of the conference and its relevance is assessed. Then the expert was asked to evaluate the article according to the following criteria:

Technical criteria:

1. Scientific merit: notably scientific rigour, accuracy and correctness.

2. Clarity of expression; communication of ideas; readability and discussion of concepts.

3. Sufficient discussion of the context of the work, and suitable referencing.

Quality criteria:

1. Originality: is the work relevant and novel?

2. Motivation: does the problem considered have a sound motivation? All papers should clearly demonstrate the scientific interest of the results.

3. Repetition: have significant parts of the manuscript already been published?

4. Length: is the content of the work of sufficient scientific interest to justify its length?

Presentation criteria:

1. Title: is it adequate and appropriate for the content of the article?

2. Abstract: does it contain the essential information of the article? Is it complete? Is it suitable for inclusion by itself in an abstracting service?

3. Diagrams, figures, tables and captions: Are they essential and clear?

4. Text and mathematics: are they brief but still clear? If you recommend shortening, please suggest what should be omitted.

5. Conclusion: does the paper contain a carefully written conclusion, summarizing what has been learned and why it is interesting and useful?

• Contact person for queries:

Professor Irina Repina, Head of the IAP RAS Laboratory, (repina@ifaran.ru)

The paper describes the development of climatologies of short-wave radiation over the ocean using visually observed cloud cover from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS). For producing climatology of short-wave radiation, we applied bulk parameterization (known as SAIL/IOARAS). For a proper computation of short-wave radiation values special effort was taken to reduce sampling errors in cloud cover from ICOADS. Specifically, we consider the uncertainties associated with temporal inhomogeneity of observations and potentially implying biases in short-wave radiation estimates related to the astronomy factors critical for short-wave radiation. For this purpose, we propose simple and effective algorithms.

Atmospheric heat and moisture transfers from the North Atlantic make the main contribution to the Arctic warming in winter. The increase in transfer is associated with changes in atmospheric circulation in the Northern Hemisphere under the influence of the sea surface temperature (SST) in low latitudes, where the bulk of the heat influx from the Sun accumulated. The mechanism of influence includes the interaction between the circulation of the ocean and atmosphere, which enhances the oceanic heat influx into the Norwegian and Barents seas, and atmospheric transport to the Arctic. SST rises with participation of orbital-forced increase of the solar insolation. Changes in insolation are small, but their effect is enhanced by feedbacks between temperature, water vapour content and downward long-wave radiation in low latitudes. An increase in water inflow, heat and moisture transfers to the Atlantic Arctic lead to increase in air temperature, water vapour content, downward long-wave radiation, and a reduction of ice thickness growth and its extent in the Barents and Greenland Seas in winter.

The positive effect of rising atmospheric carbon dioxide concentration ([CO2]) on gross primary production (GPP) is one of the factors that determine the strength of the carbon sink provided by terrestrial ecosystems. CMIP5 models tended to underestimate this effect. The study of CMIP6 simulations of GPP shows that GPP sensitivity to [CO2] assumed by increasing CO₂ seasonal-cycle amplitude falls within the range of the values assumed by model runs. This make it possible to find the weights that force the weighted mean of GPP simulations to satisfy the constraint imposed by increasing CO₂ seasonal-cycle amplitude.

The annual cycle of incoming solar radiation is the major factor that determines the amplitude of the annual cycle of the surface air temperature over the continents in the Northern Hemisphere. There are, however, other important factors that contribute to the seasonal temperature difference. The combined effect of these factors is characterized by the Gorczinski's continentality index (GCI). The gradual decrease of Moscow GCI during the second half of the 20th century could be attributed to the combined effect of the warming due to increasing atmospheric concentration of carbon dioxide and intensification of the zonal atmospheric circulation. However, these factors cannot explain the increase of Moscow GCI during the 1920-1950 period. Taking into account the Arctic temperature variations with pronounced multi-decadal variability helped us to fill this gap in the explanation of the historical changes in Moscow climate continentality.

Heating-related energy consumption depends on climatic conditions and is prone to changes in warming climate. Shortening of heating season is one of the expected effects of climate change. Since the further development and modernization of energy and heat supply systems is influenced by expectations of the climate change, studying the regional climate trends is certainly important. In this article, the authors analyzed historical changes in minimal heating-related energy demand from several Russian and European cities and show that global expectations may do not meet reality at some locations.

A slowdown of the increase of the surface air temperature (SAT) at the beginning of the 21 century has provoked the discussion for the phenomenon nature and responsible physical mechanisms. One of the most accepted hypothesis connects the slowdown of SAT rise to anomalously intensive uptake of heat energy by the deep ocean layers. We suppose that verification of the theory can be achieved via the study of the interrelationship of the surface and the deep ocean layers temperatures. Establishing the time shifts and especially the sign of the cross-correlation function of the two temperatures can shed light on the solidity of the theory background. For the aims of the study, we have used a stochastically forced two-box climate model. Analytical estimation of correlation functions and spectral characteristics of the model demonstrates that deep ocean heat uptake cannot serve as a driver of the SAT slowdown (at least in the framework of the model). The cross-correlation function of upper layer and deep ocean temperatures stays nonnegative for any time lag. It means that heat redistribution between layers cannot lead to hiatus forming. Moreover, a comparison of the two-box model and Hasselmann model spectral characteristics evidences that the deep ocean serves as a pacemaker of climate variability in the broad range of frequencies.

We have conducted a comparative analysis of the climatic and biometeorological characteristics of the regions with the largest Russian cities and have laid the basis for constructing maps of the heating season climatic characteristics for the territory of Russia. For the effective ambient temperature range of 17.2 to 21.7°C (comfort zone), we have calculated changes in the comfort zone for Moscow, St. Petersburg, Krasnodar, Novosibirsk, and Vladivostok according to data from 1959 to the present. Despite all climate differences between regions with selected cities, allowance for wind speed leads to a decrease in the number of days with temperature within the comfort zone.

The Early 20th century warming (ETCW) in the Northern Polar region was comparable by its average pace to the modern warming, but the mechanism of this climate anomaly remains a matter of debate. The key issue is to assess the contribution of internal variability and external natural and human impacts. Internal variability is one of the most likely mechanisms that may explain a large part of ETCW. This paper provides an overview of the existing mechanisms of internal climate variability responsible for the long-term climate anomaly in the mid-twentieth century.

The impact of sea ice concentration (SIC) changes in the Nordic Seas on the winter cyclone activity in the Nordic Seas is analyzed in 10-member ensemble simulations with the coupled Arctic atmosphere-ocean-sea ice model HIRHAM-NAOSIM for the 1979–2016 period. The analysis reveals that anomalously low SIC in the Nordic Seas leads to decrease in vertical atmospheric static stability, and thus may result in favorable conditions for cyclogenesis in the Nordic Seas. Our analysis also shows a statistically significant increase of cyclone frequency over the Nordic Seas under conditions of the low SIC regime.

Anthropogenic heat fluxes (AHF) have a significant impact on the weather and climate characteristics of urbanized territories. AHF plays a crucial role in the formation of an urban heat island. The structure of the urban heat island is determined not only by the AHF distribution but also by the location of the city. Moscow and St. Petersburg are the two largest Russian cities located in significantly different climatic conditions with the highest value of the AHF. In this article we compare the influence of the AHF on the temperature and wind regimes in Moscow and St. Petersburg regions.

In this study, we analyse fast (within 30 days) response of the atmospheric rivers and storm tracks positioning over the western European coast to the Sudden Stratospheric Warming (SSW) events. Analysis is done on the basis of North Atlantic Atmospheric Downscaling (NAAD) product with 14 km and 3-hourly spatial and temporal resolutions. Atmospheric rivers and cyclones are synoptic atmospheric phenomena characterized by the strong impact onto the mid- and high latitude costal zones. This impact results in extreme precipitation and wind events, floodings, long wet episodes, etc. Among other mechanisms controlling the positioning of the storm track and atmospheric rivers, we show that SSW events cause a significant southward shift of both storm track and location of the hit of the European coast by atmospheric rivers within 30 days after the SSW event. Thus, we provide a qualitative and quantitative measure of the SSWs impact on the location of the potentially extreme weather events over the European coast with 30 days predictive time scale.

The intensity of an urban heat island depends on the location, layout and development of the city, the number and density of its population, and the energy consumption of the urban economy. These dependencies can vary greatly from city to city. In recent years, more and more attention has been paid to the dependence of the city's climate characteristics on global and regional climate processes, their trends and variations. At present, there is no clear answer to the question of how climate changes affect the evolution of an urban specific city, since modern climate changes in different cases can both increase and decrease the intensity of the urban heat island. This work discusses the reasons some stabilization of the intensity of the Moscow heat island, observed in the second half of the XX century and early XXI century, and the relationship of this phenomenon with the weakening of continentality climate in the Moscow region.

The study of carbon balance of terrestrial ecosystems is considerable important for the forecasts of climate and environmental changes. Using a geoinformation-analytical method and a climate-driven regression model, we have calculated the C-CO₂ balance of natural steppe ecosystems of Khakassia and Tuva. Our research has shown that natural steppes of the region under study are a significant sink of carbon dioxide from the atmosphere. The intensity of this carbon flux in the region can be estimate as 184±41 gCm⁻² yr ⁻¹. The annual absorption of carbon dioxide in the natural steppe ecosystems of Tuva and Khakassia is evaluated as 6.9±2.2 Mt C-CO₂.

A technique is proposed for determining of the large-scale smoke aerosol fluxes using a wind field reanalysis data and the satellite monitoring data of the aerosol optical depths and the vertical profile of the attenuation coefficient. The directions of the long-range transport of the Siberian smoke haze fragments were determined in July 2016. The maximum large-scale mass fluxes and the total mass of the smoke aerosol during the transfer of air masses through the Ural meridian to the west (0.38*10⁶ ton/day and 1.38*10⁶ tons) and through the 115ºE meridian to the east (0.26*10⁶ ton/day and 0.72*10⁶ tons) were estimated.

According to measurement data on the desertified area in the Astrakhan oblast in the conditions of non-intermittent saltation, a strong influence of convective quasiperiodic structures with periods from 1.5 to 8 minutes on variations of the saltating particle concentrations are found. Statistical characteristics of the saltating particle concentrations variations are received. The vertical profile of the average particle concentration in the height range from 3 to 15 cm is obtained. An exponential approximation of the particle concentration profile with a logarithmic gradient of -0.32 cm⁻¹ is proposed. It is shown that the average particle content in the saltation layer is 8.6 cm⁻².

Threshold values of 3% and 97% percentiles of annual distribution of mean daily temperature are used to determine the cold and heat waves, respectively, for weather stations in the southern part of the Russian Far East for the period from December 1999 to 2017. Cold waves are identified mainly in December and January. The coldest winter seasons with the longest cold waves, up to 11 days, were observed in 2000/2001 and 2012/2013; the maximum total excess of negative temperatures over the threshold value was 116°C in weather station Poliny Osipenko. Heat waves were registered mainly in July. The hottest summer was in 2011, when heat wave was observed during July and August, with the longest wave at the northern Nikolaevsk-on-Amur; the maximum total excess of positive temperatures over the threshold was 74°C in Poliny Osipenko. There was no clear trend in the inter-annual dynamics of mean temperatures of winter and summer, but temperature variations can reach ±6°C and ±4, respectively. Climate extremes vary significantly during the study period, but usually rarely go beyond two standard deviations. Taking into account the possible impact of extreme temperatures on human health, their effect on the increase of mortality in Khabarovsk is discussed.

Estimates of seasonally dependent trends in the mass concentration of the near-surface aerosol are presented on the base of results of 29-year measurements at the Zvenigorod Scientific Station of the A. M. Obukhov Institute of atmospheric physics. The station is located in the woody countryside, 50 km west to Moscow. The multiple regression method is used for the analysis, in which autocorrelation of measurement data on large time scales is taken into account. Two periods are considered: 1991-2002 and 2013-2019. Excluded is the period 2003-2012 when abnormally high aerosol concentrations of unknown origin were often observed. For the periods 1991-2002 and 2013-2018, statistically significant negative trends were obtained for spring and summer seasons, respectively, and for the entire year. The spring trend in logarithm of concentration in 1991-2002 was -2.6% per year, and the annual trend was about -0.7% per year. For 2013-2019 a strong negative trend of about -6% per year was obtained in the summer season, and the annual trend estimate was -2.3% per year. The probable cause of the negative aerosol trend in the spring seasons of 1991-2002 is long-term changes in atmospheric transport. The negative trend in the summer seasons of 2013-2019 is probably due to the negative trend of summer temperature, drying and felling of spruce forest.

Analysis of fluctuations in the climate of the North Atlantic associated with the 11-year solar cycle is done using empirical data of the sea level pressure (SLP) and sea surface temperature (SST) for 1870-2012 and data of the North Atlantic Oscillation (NAO) index and Central England temperature. Emphasis is placed on the regions of the Icelandic and Azores atmospheric centers of action (CA). Methods of multiple linear regression and cross-wavelet analysis are used. The analysis reveals decadal oscillations of the SLP lagging by ∼3 years relative to the sunspot number, in the area of the Azores CA in the winter and autumn seasons. SLP variations that are approximately in phase with the solar cycle are noted in autumn in the Icelandic CA. Solar-related SLP variations in the Icelandic CA in winter occur approximately in anti-phase with the variations in the Azores CA, at smaller lag behind the solar cycle. SLP variations associated with the solar cycle are comparable in amplitude to variations due to the El Nino–Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO). SST variations associated with the solar cycle are also revealed. They are several times weaker than variations due to the AMO, but of the same order of magnitude as variations due to the ENSO. The relation of the NAO index to the solar cycle is alternating and experiences modulation with a period of about 50 years.

The paper presents results of experimental study of the physicochemical properties of surface aerosols in the Moscow region in the summer of 2019. Microphysical parameters, mass concentration and elemental composition of submicron and micron aerosol particles are considered, and their morphological structure is described. The features of variability of aerosol characteristics under atypical weather conditions prevailing in June-July 2019 are shown. The spatial distribution of the elemental composition of aerosols is established, a significant degree of their enrichment with heavy metals and metalloids is revealed. Geochemical analysis of aerosols and soils in Moscow was performed, and the coefficients of local aerosol concentration were calculated. The obtained experimental data will be useful for the refinement and verification of climate models.

In solving atmospheric dynamics problems, the influence of the gravity field inhomogeneities (GFI) is neglected. The traditional basis for this is that the amplitude of gravity variations even in highly anomalous regions do not exceed 10⁻³ ms⁻² in order of magnitude, i.e. 4 orders of magnitude less than average gravity. But in the presence of gravity anomalies, inhomogeneous forces of the same order act in the directions tangent to the mean Earth ellipsoid. The atmosphere dynamics is very sensitive to the forces of such directions. In highly anomalous regions, they are comparable with the main horizontal forces acting in the atmosphere, in particular with the forces of the pressure gradient and Coriolis forces. Therefore, it seems appropriate to analyze the possible effect of spatial variations of gravity on the dynamics of the atmosphere, primarily for mesoscale atmospheric disturbances. In a number of the authors' previous works, theoretical studies of the possible effect of GFI on the atmosphere dynamics are carried out. This report contains some new relevant findings. A three-dimensional analytical model of geostrophic wind disturbances under the influence of GFI is developed. An analogy of atmospheric disturbances caused by thermal inhomogeneities of the underlying surface and GFI is shown. Attention is drawn to the possibility of "accumulation" of atmospheric effects associated with the gravitational field inhomogeneities.

The article discusses the regional features of the Svalbard climate based on the data of regular meteorological observations obtained at Norwegian, Russian and Polish stations. Attention is paid to the spatial features of the multi-year regime of surface air temperature (SAT). Climatic norms (1961-1990, WMO recommendations) calculated from all meteorological stations, as well as long-term changes in the spatial gradients of the SAT and estimates of the range of annual fluctuations, revealed stations (area) with a "continental" and "marine" type of climate, as well as trends in spatial heterogeneities of the Svalbard climate. The rate of "modern" climate warming (1990-2016) was, on average, three times higher compared with the period after II World War (1948-2016). The continentality and abnormality of the climate are analyzed. Conclusions are formulated about a regular change in the spatial features of the climate (SAT) and the manifestation of its anomalous nature in different periods (1960-1970, 1988 and 2005-2014).

Lakes are one of the most important sources of the greenhouse gas methane. Usually, only diffusive emission is counted towards in estimates of the Arctic lakes contribution to the atmospheric methane budget. At the same time, for some regions, giving the importance for the ebullition of various genesis significantly increases previous assessments of ecosystem-based lake methane emission. This paper presents the results of a study of two gas seeps on the Central Yamal lake. The methane concentration in seep gas varies from 94.2 to 100%. Mean annual methane emission from each seep is estimated as 46.1 and 67.1 kgCH₄ per year respectively. According to the analysis of the methane isotopic composition, it is of biogenic origin. Studied gas seeps are obviously direct channels of methane emission from permafrost to the atmosphere.

The variability of Northern Hemisphere circulation types from 1899-2018 are analyzed and the classification of atmospheric circulation types in the early 21^st century are shown. These are associated with the frequency of dangerous weather phenomena, natural processes, and disasters within Russia during this time. Against this background, the synoptic conditions for the formation of extreme precipitation and floods, as well as natural fires in 2019 are considered. It is shown that an increase in the frequency of occurrence of stationary anticyclones and blocking flow regimes as well as an extension of the Mediterranean storm track was associated with an increase in the frequency of extreme precipitation and dangerous natural processes. Additionally, the occurrence of thunderstorms, often dry, led to the development of natural fires.

Data on black carbon (BC) concentrations obtained from the board of research vessels (R/V), "Acad. Mstislav Keldysh", "Acad. M. A. Lavrentyev" and "Prof. Molchanov" in 2011–2018. They were used to study the quantitative distribution of black carbon in the driving air layer over the seas of the Russian Arctic in the summer-autumn period and to determine its main source regions. Variations in the BC content in the near water layer of the atmosphere at the North Pole, in the Norwegian, Barents, Kara, East Siberian Seas and the Laptev Sea are obtained. As a result of 12 marine expeditions in the summer-autumn period of 2011 - 2018 the BC concentration in the atmospheric drive layer in the Arctic was mainly at the background level and averaged 47 ng/m³ (9-95 ng/m³). An increase in the BC concentration by several times, as shown by trajectory analysis, occurs occasionally upon receipt of air masses from the mainland, from areas of associated gas combustion. Low BC values were observed when air masses passed over the water surface from the northern regions of the Arctic. The BC concentration above the water surface depends on the state of the atmosphere in the region of soot sources on the mainland.

Polar mesocyclones (PMCs) and their intense subclass polar lows (PLs) are relatively small atmospheric vortices that form mostly over the ocean in high latitudes. PLs can strongly influence deep ocean water formation since they are associated with strong surface winds and heat fluxes. Detection and tracking of PLs are crucial for understanding the climatological dynamics of PLs and for the analysis of their impacts on other components of the climatic system. At the same time, visual tracking of PLs is a highly time-consuming procedure that requires expert knowledge and extensive examination of source data.

There are known procedures involving deep convolutional neural networks (DCNNs) for the detection of large-scale atmospheric phenomena in reanalysis data that demonstrate a high quality of detection. However, one cannot apply these procedures to satellite data directly since, unlike reanalyses, satellite products register all the scales of atmospheric vortices. It is also known that DCNNs were originally designed to be scale-invariant. This leads to the problem of filtering of the scale of detected phenomena. There are other problems to be solved, such as low signal-to-noise ratio of satellite data, and an unbalanced number of negative (without PLs) and positive (where a PL is presented) classes in a satellite dataset.

In our study, we propose a deep learning approach for the detection of PLs and PMCs in remote sensing data, which addresses class imbalance and scale filtering problems. We also outline potential solutions for other problems, along with promising improvements to the presented approach.

In this study, we investigate sensitivity of total surface water transformation to salinity from different data sources. Here we use surface salinity from NCEP CFSv2 reanalysis, GLORYS ocean reanalysis, Aquarius satellite data and ISAS-15 (product of optimal interpolation of ARGO buoys) as well as heat and freshwater fluxes from NCEP CFSv2 reanalysis. The largest spread in estimates of salinity is observed for Aquarius satellite in subpolar regions. The best correspondence between transformation computed using salinity from different datasets is observed for subtropical waters. Model-based products (CFSv2 and GLORYS) are the most consistent in estimates of surface water transformation and the largest discrepancies between these datasets are observed in the regions with high freshwater fluxes.

The paper presents the results of a study of seasonal and interannual variability of CO₂ concentration above the moist tropical forest in southern Vietnam. Experimental data were collected during year-long observation of CO₂ directly in the forest from 2012 to 2017. All data were obtained through the use of an air intake tube, placed on a metal tower at a height of 46 m and connected to a Li-Cor 820 gas analyzer (Li-Cor Inc., USA) located in a building at the foot of the tower. The values of the concentration were recorded with a resolution of 1 second; for further analysis, all data was averaged to 0.5 h values. Statistical processing based on the Fourier analysis allowed to evaluate the main characteristics of the annual distribution of CO₂ concentration, such as the amplitude and phase, as well as to analyze their variability over the years. The results of the study showed a presence of a well-determined annual course of CO₂ concentration above the canopy of the moist tropical forest.

As an index of interannual climatic variability of the atmosphere, it is proposed to calculate the weighted average over the hemisphere area (to the pole from latitude 20°) of the vertical helicity flux across the upper boundary of the planetary boundary layer, which is determined by the product of the Coriolis parameter and the square of the wind speed at this boundary. In practical calculations, the data of reanalyses ERA-Interim and ERA-20C on the wind speed at the isobaric level of 850 hPa were used. The statistical distribution of the Earth's surface area on the helicity flux values, as well as the informational entropy of this distribution, are calculated. It is shown that the introduced index usefully characterizes the interannual climate variability of the atmosphere in both hemispheres.

RIHMI-WDC carries out monitoring of the components of the climate system, such as temperature and wind speed in the free atmosphere. The basis for monitoring are global radiosonde observations accumulated at RIHMI-WDC. Reanalyses of the latest generation, characterized by high temporal and spatial resolution, are also a source of data for climate monitoring of the free atmosphere. The article presents the results of comparison of time series from different sources, discusses the features of the distribution of the upper-air temperature and wind speed over the northern hemisphere, as well as their trends. A comparison of the results obtained from various sources is discussed.

The urban heat island (UHI) in Moscow was for the first time studied not only at the ground air level, but also at different heights, depths and on the surface using stationary, radiosonde and satellite data. Long-term dynamics of the UHI intensity in the ground air layer has been estimated since the end of the 19^th century both as traditional 'maximal intensity' (the difference between the city centre and rural zone), and as 'average intensity' (the difference between all urban and all rural stations). In recent years they have been 2.0 and 1.0 ºC, respectively. The quasi-stabilization of both parameters in the second half of the 20^th century was probably the result of extensive city growth at that time; the new increase in the UHI intensity seems to be connected with the densification of urban development and heat sources in the last 20 years. The mean daily vertical extension of the UHI in the atmosphere is approximately 300 m. In the upper soil layer (up to 160 cm deep) the maximal UHI intensity was about 1.6-1.7 ºC half a century ago. The average UHI intensity at the field of the surface temperature in recent years is 2.7 ºC.

El Niño (EN) and La Niña (LN) manifestations in the air surface temperature fields over the Europe are studied in present paper using pan-European E-OBS 19.0e gridded data for 1950-2018 and 20CRv2c reanalysis data for 1870-2014. Particular accent was put on winter severity in the Azov Sea region. Taking into account the Eastern and Central types of both EN and LN events sorted out previously, composites of monthly and ten-day air temperature anomalies were obtained for each type of events. The anomalies of each month from October "0" year (the year when event began) to April "+1" year (the year following "0" year) were analyzed. The typical features of statistically significant manifestations in European air temperature for the Eastern and Central types of EN and LN events were described.

This paper describes the characteristics of atmospheric surface layer and heat balance components of snow-ice cover during drift of RV "Akademik Treshnikov" to the north of the archipelagos Franz Josef Land and Svalbard, in the area 80 - 82N, 30 - 45E, in comparison with observations at drifting station North Pole-35", worked in the same area in April 2008, and "Ice Base Cape Baranova" in April 2019. Characteristics of atmospheric surface layer and the energy exchange processes during the drift of the expedition"Transarctica-2019" were significantly affected by the presence of clouds and the state of the ice cover. The influence of these factors led to a decrease in the radiative cooling of the surface, the formation of a warmer and wetter ABL and to a weakening of the turbulent exchange between the atmosphere and the snow-ice cover. Comparison of energy exchange characteristics, calculated for the Bolshevik Island (79° N) and for expedition "Transarctica 2019" area shows good agreement between the monthly averaged values and trends in heat fluxes, despite the fact that in the first case the underlying surface was sea ice cover, and in the second it was the land surface.

It is shown theoretically that the tendency of the height of the isobaric surface of 1000 hPa is proportional to the integral helicity of the geostrophic flow. This result is confirmed by calculations.

The features of the dynamics of long-range atmospheric pollution of the territories of the Russian Federation under current conditions, in the immediate and distant prospects (from 1980 to 2050) taking into account two scenarios of the changing climate in the 21st century were studied. To assess contribution and trends of long-range atmospheric pollution in Russian regions, a two-dimensional numerical model is constructed, which implements the solution of the coupled problem of transport and diffusion of impurities in spherical coordinates, as well as an improved method for identifying sources of transboundary and local air pollution. The results indicate general trends in the directions of the flow of pollutants to the Russian regions in 1980-2050 from zonal (western) to meridional (southern). Such dynamics is markedly expressed in the regions of Siberia and the Far East and slightly in the European territory of Russia and the Urals. In the climatic scenario RCP8.5, despite the general tendency towards the southern transport of impurities, a certain dispersion of directions from where the regions are polluted becomes noticeable. It indicates an increase in atmospheric pollution from the west in certain regions, mainly in the central part and in the south of the ETR. The greatest danger to long-range atmospheric pollution of the regions of Siberia and the Far East in the coming decades will be sources located south of these territories; of the regions of the ETR and the Urals – sources located to the west and south. These results are important for the development of proposals for ensuring the environmental safety of Russian regions and for planning economic development of the country's territories that affect the pollution of the environment of ecologically significant zones.

We present an assessment of changes in the gas hydrates stability zone of the Arctic Ocean associated with subsea permafrost conditions. To evaluate the formation and dissociation of gas hydrates under the climatic conditions of the last glacial cycle, it is necessary to understand how the thickness of the permafrost has changed after flooding by the sea. To do this, we have combined two numerical models: a model of permafrost dynamics based on the paleoclimatic scenario of changes in temperature and ocean level, and a model of the methane hydrates stability zone (MHSZ). Calculations of changes in the thickness of the submarine permafrost and the MHSZ were carried out for the period of 120 thousand years. Our results show that, although changes in the bottom water temperature over the last-decades period affect the hydrate stability zone, the main changes with this zone occurring after flooding the Arctic shelf with the seawater. As a result of the combined simulation of the permafrost and state of MHSZ, it was found that in the shallow shelf areas (lower 50 m water depth) after flooding, the hydrate presence conditions in the upper 100-meter layer of the MHSZ are violated. This suggests that the methane coming from this reservoir is concentrated in the bottom sediments of the shelf, and then released into the water, continuing to adapt to changing sea levels, rising bottom water temperatures, and subsea permafrost melting.

Diagnostics of La-Nina events from 1900 to 2018 is done in this paper using COBE SST2 data sets. Two La Niña space-time types were selected on the basis of two methods. The first of them is empirical orthogonal functions method. The second one is hierarchical cluster analysis. Both of methods showed the absolute identity two selected types. Analyzing the spatiotemporal series of the sea surface temperature anomalies (SSTA) in the equatorial Pacific two main EOFs were obtained. The first EOF mode describes ∼46% of the total dispersion SSTA variability in the equatorial Pacific and demonstrated two consecutive La Niña events that arise after the strong canonical El Niño. The second mode accounts for ∼ 21% of the total dispersion SSTA variability and shows a nature of the East Pacific La Niña occurrence.

Trends in current global and regional climate change are estimated based on observations and reanalysis data, as well as on the basis of model simulations. Special attention is paid to climate changes in the Arctic and North Eurasian regions. Temperature and sea ice changes in the Arctic and Antarctic are compared. The processes contributing to the enhancement of regional climate variability are considered. The role of natural and anthropogenic factors in climate change and the ability of models to adequately simulate current climate changes are assessed. Possible changes in relative contribution of natural and anthropogenic CO₂ and CH₄ emissions in the North Eurasian regions under global warming are discussed.

A significant reduction of the Arctic sea ice extent enhances the sea waves activity in the Arctic Ocean. In this paper we analyze characteristics of wind waves activity in the Arctic basin using the WAVEWATCH III model simulations forced by wind and sea ice fields derived from the CMIP5 global climate models under different scenarios. A relative contribution of wind seas and swells to the total sea waves activity in the Arctic basin from model simulations is assessed and compared to that based on reanalysis data and satellite observations. Possible changes of sea waves characteristics from model simulations for the 21st century with anthropogenic scenarios are estimated. Regional estimates of various states of sea waves (such as wind seas, swells and their interaction, chop-like events) are performed, in particular for the Atlantic sector of the Arctic basin.

In this study, we evaluated the climatology and interannual variability of marine cold-air outbreaks (MCAOs) in the Russian Arctic marginal seas (from the Barents to Chukchi seas). We used a simple index for identifying MCAOs based on the vertical potential temperature gradient between the sea surface and the 800 hPa level. We calculated the index using 6-hourly Era-Interim data for the 1979–2018 period. Given the index, we evaluated spatial and temporal variability of weak, medium, and strong MCAOs frequency as well as their dependence on sea-ice concentration using non-parametric tests. The most intense MCAOs were found in the Barents and Kara seas. The annual cycle maximum for the western Russian Arctic (WRA) were found in wintertime, while it was revealed in mid-late autumn for the eastern Russian Arctic (ERA). In the WRA, we found a statistically significant decrease in amount of strong MCAOs in winter and late autumn and a general strengthening of MCAOs in spring. Meanwhile, over the ERA region, increase of moderate and weak cold-air intrusions during October and November was revealed.

The paper considers the problems and features of the functioning of the energy complex in the regions of the Russian Arctic under the influence of global climate change. Particular attention is paid to new ideas and developments intended for practical use in developing measures to adapt to the adverse effects of climate change. The issues of optimising the composition and structure of the energy economy of the Arctic territories in the areas of permanent residence, reducing the burden on natural ecosystems, and risks in the field of sustainable economic and social development of the Arctic region are discussed. The ways are proposed for developing new approaches to the formation of a strategy for the development of the region's energy infrastructure under the influence of climatic and environmental factors on the natural environment. The mechanisms of the impact of changes in the climatic characteristics of the region on the operating conditions and the efficiency of energy facilities of the fuel and energy complex are determined. The degree of this dependence was studied for different types of infrastructure facilities of the fuel and energy complex. The data on the assessment of the impact of global climate change on the infrastructure of the fuel and energy complex and the possibilities for its adaptation, which include: the implications for power generation facilities; impact on energy transportation; problems of thawing permafrost and solifluction; climate impact on energy consumption and socio-economic effects; the role of distributed energy and renewable energy in adaptation to climate change. It is shown that for the territories of the Russian Arctic with isolated energy supply, the development of energy-efficient systems and renewable energy will reduce climate risks for sustainable growth. Not only of this power sector but the whole economic complex of the region due to both their better adaptation to the effects of climate change and the reduction of technogenic greenhouse gas emissions, which are one of the main factors of these changes.

The results of the study of the spatio-temporal variability of the main characteristics of jet streams and turbulence zones in the upper troposphere of the Northern Hemisphere according to measurements from European geostationary meteorological satellites for the period 2007 - 2018 are presented. Their relationship with the essential parameters of the Earth's climate system — the temperature of the troposphere, the area of sea ice, and also large-scale atmospheric phenomena is considered. It has been shown that over the past 12 years there has been a significant increase in the area of regions occupied by relatively weak and moderate turbulence and a slight decrease in areas with strong and very strong turbulence. Based on the cross-wavelet analysis in the time-frequency space, the relationships between the variations in the areas of the turbulent regions and the majority of the characteristics of jet streams are revealed. A close relationship has been established between the characteristics of jet streams and the areas of turbulent zones with the temperature of the upper troposphere. In this case, the effect of temperature on the area of turbulent zones manifests itself indirectly through the characteristics of jet streams. A significant association of variations in the average area of the jet stream and the latitudinal position of its center with the area of sea ice are noted. According to spectral and wavelet analysis of the characteristics of jet streams, along with annual and quasi-biennial oscillations, short-period oscillations are observed with periods in the range of 10-40 days, which can be interpreted as a manifestation of Rossby waves..

We present observation results of methane (CH₄), its isotopic signature (δ¹³C^CH4) and carbon dioxide (CO₂) surface concentrations, made aboard the research vessel (R/V) "Akademik Mstislav Keldysh" in the Russian Arctic seas in summer 2019. The main goal of the study is to determine the possible sources of methane. As a result of the study, localized areas with an increased methane concentration (up to 2092 ppb) in the surface layer are identified. It may be related to the advection of water masses rich in organic matter from the Ob and Yenisei Rivers. In addition, increased methane concentrations (up to 2010 ppb) are observed in the Kara Sea near the Yamal Peninsula, where gas deposits are concentrated, and active methane emissions from wetland ecosystems are noted. We conclude that the average concentration of methane in surface air in the Arctic seas is determined mainly by large-scale transport of air masses.

We observed the surface concentration and isotopic composition (δ¹³C_CH4) of methane (CH₄), ozone (O₃), nitrogen oxide (NO/NO₂) and carbon monoxide (CO), as well as black carbon (BC) content in the Russian Arctic seas aboard the research vessel. The effect of emissions from the vessel chimney on the data obtained is analyzed. We investigate the local areas of CH₄ emissions from seabed where the concentration of CH₄ can increase to 3.5 ppm. Notwithstanding that fact, mainly large-scale processes of air mass transfer determine the average concentration of methane in surface air in the Arctic seas. In addition, we analyze the distribution of BC along the route of the vessel. It was found that excess concentrations of BC over background values are observed occasionally during advection of air masses from the mainland, from areas of associated gas burning and forest fires.

Polymodal (bimodal) features of the probability density functions (PDFs) for long term series of surface air temperature anomalies in transitional (fall, spring) seasons are studied based on daily data from meteorological observations in various North Eurasian regions using a stochastic energy balance model. The observed PDFs are characterized by bimodality with the minimums laying near 0° C. Changes of weather regimes since the middle of 20th century until recent years are analyzed. The increase in probability of negative temperatures for both transitional seasons in the 21st century compared to the 20th century can be linked to global changes in atmosphere circulation patterns and, particularly, to intensification of cold air outbreaks occurrence in spring seasons. "Indian summer" (the effect of recurrent warming in fall seasons) phenomenon is stronger in the 20^th century PDF, while the bimodality of PDF around 0° C can signify the nonlinear dependence of albedo on SAT.

Climatic changes in the Middle Volga District observed from 1828 to 2018 are examined. Long-term air temperature variations are monitored using observation data from Meteorological Observatory of Kazan University (MO KU) (1828-2018), and from 5 meteorological stations located in Orenburg, Penza, Perm, Saratov, Ufa (1885—2018). Spatiotemporal variability of the air temperature and atmospheric precipitations is researched in the Volga Federal District (VFD) on the basis of data from 200 meteorological stations (1954-2018) and NCEP/NCAR, ERA-Interim, ERA5 reanalysis data (1979-2018). The general tendency towards the air temperature rise has been identified for the period considered (in Kazan the annual air temperature mean increased by 4°ccccc from 1828 to 2018). It has also been revealed that the number of days with the minimum temperature (below -20°ccccc) tends to decrease throughout the year, while the number of days with the maximum temperature (over 25°ccccc) tends to increase. The dynamics of the low-frequency component with the period exceeding 15 years is studied for normalized air temperature and atmospheric precipitation anomalies in the VFD between 1954 and 2018. Distribution of great air temperature anomalies within the studied period is evaluated.

The results of studies of atmospheric aerosol over the territory of Russia are of great interest from the point of view of environmental and climatic problems. The article presents the results of the spatial-temporal variability of aerosol optical thickness (AOT) over the Asian Part (AP) of the Russian Federation in recent decades. The Database (DB) "Aerosol optical thickness of the atmosphere from satellite and ground-based observations" created by the authors was used. The presented trends in AOT changes (annual values, summer values) and statistical estimates of real empirical series show that there is a good agreement between the annual values of AOT for satellite and ground-based values, for monthly values the discrepancy has more value. Based on observational and reanalysis data, the interannual variability of the average annual and average summer values of the total radiation flux coming to the surface was studied. The empirical typification of interannual changes in the intra-annual course of the cloud cover values (%) over the considered time interval was carried out. The analysis was performed for the Tiksi Arctic station and for the Yakutsk, Ussuriysk, Irkutsk and Yekaterinburg stations located in the AP of the Russian Federation.

Coastal and fast ice polynyas in the Arctic seas can have a noticeable effect on the Arctic climate, increasing the temperature of the cold air which coming from continental Siberia in winter to these seas and in the Arctic basin [1-2]. In this paper, were studied the effect of polynyas on surface air temperature and on the meridional heat and moisture transfers according to expeditionary observations and ERA-Interim reanalysis. According to the results of expeditionary observations carried out in the 1990s, estimates of heat inflows from the surface of the polynya were calculated. From reanalysis, meridional heat transfers were obtained through 70 ° N, air temperature profiles, wind speed in the region of the Laptev Sea (100 - 140 ° E.), and polynya which located in the Laptev Sea (120 - 130 ° E). It was confirmed that winter transfers of cold air from the mainland do not have a cooling effect on the average winter air temperature north of 70 ° N due to the heating effect of polynya.

An analysis of the CO and CH₄ total column (TC) as well as aerosol optical depth (AOD) data in background and urban Eurasian regions for different time-periods and seasons from 1998 to 2018 years is presented. Trend estimates based on long-term spectroscopic datasets of OIAP RAS for Moscow, Zvenigorod (ZSS, Moscow province), Beijing (joint site of OIAP RAS and IAP CAS) and NDACC stations located in Eurasia are compared between themselves and with similar assessments obtained from satellite data. The comparison of satellite and ground-based trend estimates was provided for the days of synchronous measurements only. Analysis results of the satellite observations of AIRS v6 of CO and CH₄ TC and MODIS AOD data are confirmed by ground-based trend estimates. Significant decrease of anthropogenic CO in the megacities Moscow (2.9±0.6%/yr) and Beijing (1.2±0.2%/yr) for autumn months of 1998-2018 was found according to ground-based spectroscopic observations. In spite of total anthropogenic CO emission decrease (for Europe and China) and the decrease of wild-fires emissions in Central North Eurasia (0-90° E, 42-75° N) in 2008-2018 we found CO TC stabilization or even increasing for summer and autumn months of 2008-2018 in background regions of Northern Eurasia. Decrease of AOD over Central and Southern Europe as well as over China (1-5%/yr) was observed since 2007. Since 2007-2008 an increase in CH₄ TC positive trend values over Northern Europe as well as for tropical belt of Eurasia was obtained.

Sea ice plays a significant role in the Earth's climate system. Significant changes are currently taking place in the sea ice cover area. The structure of sea ice also is changed. Based on field measurements, the paper shows the importance of taking into account the morphometric (structural) inhomogeneities of sea ice for modeling its interaction with the atmosphere. The dependence of the drag coefficient and the aerodynamic parameter of roughness on the surface structure is considered. The drag coefficient nonlinearly depends on the ice concentration, the relative area of the puddles, on the width and configuration of the leads, on the spatial location and height of the hummocks, as well as on the atmospheric stability. The parameterizations proposed in the paper can be used to calculate fluxes in weather and climate models.

The magnitude of climate change in Arctic is greater than in other regions. Climate projections confirmed the ongoing warming in the circumpolar areas. The study goal was to estimate the fraction of mortality attributable to the exposition to non-optimal ambient temperatures during the 21^st Century under the selected IPCC Representative Concentration Pathways RCP4.5 and RCP8.5. Three study areas were chosen to represent the different types of subarctic climate: from marine-type to transitional to extremely continental. Our dataset comprised 160363 deaths occurred between 1999 and 2016 in the cities of Murmansk, Archangelsk and Yakutsk. Non-linear distributed lag model was used to estimate the relationship between daily air temperatures and mortality rates. Daily temperature anomalies projected by the decades 2050-2059 and 2090-2099 were derived from the ensemble modelling with the regional climate model developed in the Voeikov Main Geophysical Observatory. The study showed positive net health impacts in all locations, and indicated uneven distribution of the benefits of climate change. Under the RCP8.5 scenario, mortality from all natural causes in the age group over 30 years will decrease by 4.5% (95% CI 1.1%; 7.9%) in Murmansk, 3.1% (1.1%; 5.1%) in Archangelsk and 3.6% (0.3%; 7.0%) in Yakutsk between the decades 1990-99 and 2090-99.

In this paper we present first results on the use of Polar WRF model for regionalization of the atmospheric circulation in the Arctic region produced by the global climate model INM-CM48 developed in INM RAS. We demonstrate that Polar WRF does not show run off effects in the first year of integration, gives reasonable results with respect to the global model with more details in the regions of complex topography and coast line.

The simulations for the last millennium with an Earth system model developed at the A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM) are performed. These simulations are forced by changes of the parameters of the Earth orbit, total solar irradiance, volcanic (stratospheric) aerosols optical depth (only since 500 C. E.), atmospheric concentrations of greenhouse gases (CO₂, CH₄, and N₂O), land use, tropospheric sulphate burden, and population density. It is found that the externally forced part of the terrestrial carbon cycle (TCC) interannual variability (IAV) was mostly driven by volcanic activity in the preindustrial part of the last millennium with an increase of importance of anthropogenic forcing during the 20th century. The latter enhanced IAV in the 20th century. For different time intervals and for different kinds of external forcing, coefficient of variation of IAV in different TCC characteristics is smaller (typically, up to few percent) in forested regions and larger in the regions covered by grasses (e.g., in tundra), where it could be as large as several tens of per cents for fire return interval. We show that the externally forced IAV of gross primary production during the 20th century dramatically increased as compared to that during the preindustrial period. In addition, the land use activity increases the relaxation time scale of the vegetation carbon stock by one order of magnitude.

The influence of stratospheric processes on the troposphere is defined by a multifactorial mechanism containing various geophysical and photochemical processes. This interaction determines the weather and climate of a particular region of the Earth. The number of sudden stratospheric warmings (SSW) over Eurasia has doubled over the past 20 years if compared with the second half of the 20th century. As a result, one had an increase in dangerous weather phenomena associated with those stratospheric-tropospheric interactions. In this regard, there is a certain need for an early forecast of such dangerous weather phenomena and their study within the framework of the climate of a given region. The paper presents a possible mechanism of the interaction of the mesosphere, stratosphere and troposphere layers (the so-called "ozone mechanism"). Due to its orographical and geographical position, the northern region of the East European Plain is characterized by accumulation of total ozone (TO) over this territory and formation of sharp and severe colds during SSW. The conclusion is made about the key contribution of the "ozone mechanism" to the development of SSW in 2018, which has become the largest in the Northern Hemisphere over the past 20 years.

Analysis of the monthly average surface air temperature (SAT) data of the White Sea showed its significant growth over the past decades. Against the background of this growth, the interannual variability was revealed with periods close to the periods of El Niño – Southern Oscillation (2-7 years) and the North Atlantic Oscillation (7-10 years). The effect of these oscillations on the interannual variability of the SAT of the White Sea is shown and the periods of their synchronization and desynchronization are found. During the periods of 1960s and from the second half of the 1980s to the mid-2010s during the El Niño events in the White Sea negative SAT anomalies were usually observed, and during the La Niña events – positive anomalies. In the period from the late 1960s to the mid-1990s, NAO had a strong positive effect on the SAT anomalies of the White Sea, in the second half of the 1990s this influence changed its sign, but from the beginning of the 2000s it became positive again.

From the data of observations at 43 aerodromes in European Russia and the neighboring countries for 2001-2018, linear trends are calculated of temperature, humidity, and pressure, and then compared against the temporal changes in pressure field patterns. The latter are estimated on the basis of objective analysis data, using a special software. The linear trends show that the trends of annual-mean and season-mean temperature are positive practically at all the sites, though mean temperature in separate months can exhibit both decrease (in January) and strong increase (in December and summer months). The annual mean dew-point deficit increases in time almost everywhere, while surface pressure increases in the north (larger) part of the area and decreases in its south part. It is shown also, by means of objective classification of pressure field patterns, that the growth of cyclonic situations occurrence frequency dominates in the south part of the area, and the growth of anticyclonic situations occurrence frequency dominates in its main, north part. This result is consistent with the pressure trends distribution over the area.

Four global wind wave hindcasts based on ERA5, MERRA2, ERA-I and CFSR reanalyses and spectral wave model WAVEWATCH III for the period from 1980 to 2017 have been validated against satellite altimetry and NDBC buoys for 1 year. Hindcast based on newly released ECMWF reanalysis ERA5 demonstrated the best agreement with both satellite altimetery (with normalized bias being up to 5%, and RMSE up to 0.5 m) and buoy measurements, including values of upper percentiles. In general, all hindcasts show good correspondence with the observational data and thus can be used in further wind wave climate studies.

Under the influence of large planets (Jupiter, Saturn, Uranus, Neptune), the Sun moves in outer space along a certain trajectory around the common center of mass of the solar system. Earth follows the sun. It is assumed that part of the barycentric rotation moment is transmitted to the Earth's rotational moment and zonal currents of the World Ocean. The aim of this work is to obtain estimates of the possible impact on the climate system of additional rotation forces arising on the Earth during the barycentric movement of the Sun around the common center of mass of the Solar system. The climate system is considered as an oscillatory system, which can resonantly perceive external repetitive effects at its own frequencies. The index of the dynamic influence of barycentric rotation on the speed of the axial rotation of the Earth, on the surface temperature of the ocean and on El Nino is proposed. An asynchronous correlation analysis is performed. It is shown that the influence of the dynamic forces of barycentric rotation describe 31% of the total variability of the Earth's rotation speed with a delay of 5 years, 66% describes the variability of the average annual temperature of the ocean surface in the circumpolar Antarctic current with a delay of 32-37 years. The contribution of the moment of inertia to the total SST variability along other ocean currents is from 25 to 50% with the same delay. It was found that the El Nino phenomenon is a consequence of variations in the circular circulation of oceanic waters in each of the hemispheres of the Pacific Ocean. One of the engines of these variations are perturbations of the ocean circulation in the region of the Antarctic current. The contribution of changes in SST in the Antarctic Current to changes in the NINO3 index is 31%.

Impact of climatically significant anthropogenic and natural emissions to seasonal ozone (O₃) variations observed at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia in 2007–2012 have quantitatively been estimated using GEOS-Chem chemical transport model. It is shown that the formation of a stable continental pollution plume from sources in Western Europe, European Russia, and southern Siberia plays an important role in regional balance of near-surface ozone and allows to explain up to 15%–17% of the amplitude of O₃ annual cycle observed at ZOTTO (∼5–6 ppb).

Along with field and satellite data, the calculation of fluxes using integral parameterizations can become a source of information about incoming shortwave radiation fluxes on the sea surface. In this work, we used the results of applying the SAIL parametrization created at the IO RAS, based on measurements of incoming shortwave radiation fluxes to the surface of the Atlantic Ocean and the corresponding meteorological parameters. The main task of such parameterizations is to construct climatology of shortwave radiation fluxes according to VOS data. In the course of the work, the new cloud climatology CLAAS ed.2 was used as input to calculate the average daily fields of the incoming shortwave radiation fluxes to the surface of the Atlantic Ocean. As reference data, we used a satellite database of shortwave radiation fluxes for the Atlantic Ocean - SARAH ed. 2. In conclusion, it can be noted that the SAIL parameterization works very well for a total cloud score of up to 4 octa. Further development of the SAIL parameterization is possible by separately taking into account the direct and diffuse flux of incoming shortwave radiation, since as part of the growth of possible cloud regimes, it is very important to know when the flux prevails over the diffuse and when vice versa.

Every aspect of human activities in the Arctic faces a wide range of risks. By the beginning of the XXI century, mankind had recognized a new class of risks, namely the risks associated with anthropogenic climate change, which is more noticeable in the Arctic, where the rate of warming is twice as high as the world average. The global and especially Arctic climate is likely to continue to change, thereby significantly affecting future socio-economic development, biodiversity, ecosystems and human society. In this paper, we consider climate risks associated with socio-economic development of the Russian Arctic, and propose a modelling framework that allows stakeholders to identify and manage climate risks, assess the economic impacts of climate change in the Arctic, and assist in the development of climate change adaptation strategies.

The paper presents the results of monitoring the aerosol characteristics in the near-ground layer of the atmosphere at the Aerosol Station of the Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences (IOA SB RAS) located at the southeastern outskirts of city of Tomsk and in the background forest area (the Fonovaya Observatory, ∼ 70 km to southwest from Tomsk) in 2014 – 2018. The data were considered on the concentration of aerosol and absorbing substance (soot, black carbon) at two measurement points, as well as the hygroscopic properties of aerosol particles. The features of the annual behavior and interannual variability of the anthropogenic contribution of the city to the average values of aerosol characteristics are analyzed. A significant trend by 7% per year was revealed for an increase in the soot fraction of aerosol under urban conditions. The typical diurnal behavior of the aerosol and soot concentrations at the Aerosol station is characterized by an increase in these parameters at 21-23 hours local time compared to daytime hours. Also a significant decrease in the aerosol hygroscopicity is observed in evening under urban conditions.

To achieve better agreement of simulated Arctic winter stratospheric dynamic with observations assimilation procedure nudging was incorporated in CCM SOCOL. Trajectories based on SOCOL output winds demonstrate the reasonable agreement with trajectories based on reanalysis data inside the polar vortex and can be used for analysis and forecast of ozone related processes in winter-spring seasons. Obtained results of several recent major Arctic SSW events analysis show that CCM SOCOL could be used for SSW forecast over the period up to 8 days.

This paper reports on various aspects of the urban heat island (UHI) of the Moscow megacity – its spatial and temporal variability and linkages with human thermal comfort. Firstly, we analyze long-term trends of air temperature, UHI intensity and thermal stress indices based on meteorological observations over the period 1977-2018. We show that the city exhibits 40% higher rates of summertime climate warming than the countryside, as well as higher rates of human thermal comfort deterioration. Secondly, we present a new approach for spatially-resolving urban climate studies and real-time monitoring applications based on the usage of crowdsourced air temperature data from Netatmo citizen weather stations (CWSs). The CWSs provide uncertified and often misrepresentative data. However, their quality could be controlled by application of statistically-based algorithms. Additionally, we have experimentally evaluated uncertainties of the Netatmo temperature observations and regard them to be acceptable for UHI studies. Observations from more than 1500 CWSs as well as reference observations were used to analyze spatial patterns of the summertime nocturnal UHI. Both types of data shown an UHI covering the whole city and its suburbs, with a tendency of a temperature decrease with the distance from the city center. As a prototype a monitoring application, based on CWS data, we developed a web-service for real-time temperature mapping in Moscow, which is available at http://carto.geogr.msu.ru/mosclim/.

The article present a reconstruction of the late spring–summer (May–July) precipitation for the Zilair plateau (Southern Urals) based on latewood width chronologies of Scots pine (Pinus sylvestris L.) for the 1776–2015 period. Wavelet analysis revealed a number of characteristic periodicities in the reconstructed precipitation variability. Cross-wavelet analysis using indices of solar activity (SA), Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO) showed co-variability of the precipitation with SA at about 20-yr, sporadic links to NAO on multi-year to decadal time scale, and a robust link to AMO at multidecadal time scales.

Polar mesocyclones, also known as polar lows (PLs), are important maritime mesoscale (horizontal diameter up to 1000 km) weather systems at high latitudes, forming to the pole from the polar front. We consider the possible prognostic criteria of the PLs, in particular, the kinematic helicity as a squared characteristic related to the integral vortex formations and kinematic vorticity number. To calculate such characteristics we use reanalysis data and the results of numerical modeling with the WRF-ARW model for the PLs over the Nordic (Norwegian and Barents)seas. For comparison, experimental data are used. Our estimation of the helicity is based on its remarkable property – the connection of integral helicity content in the Ekman layer with the geostrophic wind velocity. Criteria associated with vorticity and helicity manifested through the PL genesis and development quite clearly. This criteria can be used to increase the efficiency and accuracy of complex forecasting techniques.

In this study we examine the sensitivity of the high-resolution regional ocean model solution to the atmospheric forcing of low (70 km - LoRes) and high (14 km - HiRes) spatial resolutions over the North Atlantic. To force the regional set up of NEMO ocean general circulation model (OGCM) we use the North Atlantic Atmospheric Downscaling (NAAD) product, which is the result of the Weather Research and Forecasting (WRF) atmospheric GCM with ERA-Interim as a boundary condition. Increase of the of the resolution of the atmospheric forcing and thus, representation of the surface turbulent heat and radiative fluxes in HiRes and LoRes atmospheric forcing, cause the 1.5° negative difference between sea surface temperature and -0.15 PSU in sea water salinity over the whole domain. The output of the OGCM forced by the high-resolution atmosphere is almost equal to the observational datasets. More intensive turbulent heat loss from the ocean surface and ventilation processes result in lower ocean heat content in the upper ocean (0-700 m) and at intermediate depth (700-1500 m) when the model is forced by HiRes. HiRes-driven experiment shows more intense coastal currents and less intensive large-scale currents. Ventilation processes are sensitive to the mesoscale atmospheric events representation: HiRes experiment provides deeper by 100 m mixed layer depths and its later in time deepening and restratification.

The features of the spatial and temporal distribution of the main meteorological values in the Northern Hemisphere in 2019 are considered. A brief description of climate change on the background of long-period variability of extreme meteorological phenomena, which identified by WMO climate indices, is given. Quartile analysis and nonparametric Mann-Kendall criterion are used to assess the significance of changes in the frequency and intensity of extreme meteorological phenomena in different regions of Russia. The increase in the growth of the average temperature in the Northern Hemisphere in the spring and summer of 2019 compared to 2018 and early 2019 is noted. The prolonged large-scale anomalies of weather regimes were observed in the warm period of 2019: heatwaves in Western Europe, in the south of European Russia, in Siberia, Alaska, and as well heavy rainfall in the Irkutsk region and in the south of the Far East. Possible mechanisms of weather and climate changes in the Northern Hemisphere are discussed. The focus is on the Arctic, which is the most vulnerable to climate warming. It is concluded that, with an abundance of physical hypotheses, there are many contradictions and uncertainties in the study of the mechanisms of weather and climate variability. Solving the problems requires further research based on modern technologies, the development of satellite monitoring systems and hydrodynamic modeling.

Impact of climate change on the Ob, Lena and Yenisei runoff is under discussion. Indexes of zonal, meridional and general circulation were used to assess the effect of changes in atmospheric circulation. Correlations between the indexes and surface air temperature, precipitation, atmospheric moisture content in the regions of catchment areas confirmed the influence of atmospheric transport in the cold part of the year. Assessment of the relationship between changes of climatic conditions in the catchment areas and interannual changes of river runoff parameters indicated that annual runoff increases and mostly is affected by increase of average annual precipitation. Frequency of maximum river discharges during climate warming is reduced.

The paper presents the results of applying the continuous wavelet analysis method to assess the cyclic components of discrete time series. The work is based on an analysis of a long-term series of data on observations of air temperature in the south-west of the Valdai Upland, as well as analysis of data on observations of CO₂ concentration in the canopy of the tropical monsoon forest in southern Vietnam. The patterns of wavelet coefficients and integral spectra have been studied for all considered time series. Additionally, the cyclicities contained in the studied series were revealed.