Thermal Comfort of The Palabuhanratu Tourism Area

The development of tourist areas is highly dependent on their facilities and attractions. The comfort level greatly affects nature-based tourism, which is based on outdoor activities. Palabuhanratu is popular with tourists because of its natural attractions, such as its beaches, water sports, and the new Ciletuh Geopark. The temperature and humidity of the air at the surface influence how comfortable travelers are in the area. These parameters are to be sensed directly by tourists participating in outdoor activities. The Temperature-Humidity Index (THI), based on the two climate parameters mentioned above, is used to show the comfort level. Spatiotemporal analysis based on GIS is used in this study, utilizing the ERA5 Reanalysis data for 1991–2020. The goal of this study is to find out how climate impacts comfort levels so that people can know when the best time is to visit. The THI values are highest in May, which means that this is the worst time of year to go to the area for outdoor activities. An examination of the diurnal pattern of THI is also carried out to demonstrate the sub-daily scale variation for further consideration.


Introduction
The tourism sector serves a crucial purpose in development, extending beyond its role as a source of foreign exchange for the country and income for regions, it also contributes to the economic advancement of local communities [1].A growing tourism industry can have both positive and negative consequences; referring to this, a rise in the number of visitors can have a negative impact while tourists use tourism potential greater than the capacity possessed by tourism [2].[3] stated that apart from topography, geography, landscape, vegetation, and fauna, weather/climate factors affect the attractiveness of tourism in a region.Also corroborated by [4], Climate knowledge is an important consideration when selecting tourism sites.
Regional connections and weather/climate factors are the most important parts of the analysis when it comes to the comfort factor.Both a climate comfort index and a thermal comfort index can be used to measure these factors.Tourist attractions are associated with four distinct types of human comfort: spatial comfort, visual comfort, auditory comfort, and thermal comfort.The outdoor temperature conditions are the most determining factor in nature tourism activities for being able to do activities well and carry out outdoor activities.Furthermore, the beach area is well-known for its abundance of sunshine, sandy areas, and open spaces; this condition makes tropical climates hard to live in because they have a lot of rain, air temperatures that are usually too high for comfort, a lot of sun, and enough moisture in the air to make it hard to stay warm [5].In Palabuhanratu District, which has a tropical climate and is part of the Sukabumi Regency, the humidity is very high, reaching 100% from night until morning.Sukabumi Regency's temperature trend is generally positive in 2021, with monthly minimum and maximum temperatures found to be stable, with variations of around 0.28°C per year.Rainfall reaches 2500-6000 mm per year, with average monthly rainfall between 40 and 500 mm per month.
Air conditions can be considered comfortable if a portion of human energy is allocated to productive work, while the body's temperature regulation efforts remain minimal.Quantitatively expressed as the Temperature Humidity Index, abbreviated as THI, was first developed by [6] and modified by [7] for the tropics.Climatic phenomena affect the physiological comfort in residential areas.In addition to thermal comfort conditions, climate conditions affect human activities.Climate comfort takes into account climate parameters, in this case, the parameters of air temperature (ᵒC) and relative humidity (%) to determine comfort and adaptation to thermals and can be using the Temperature Humidity Index (THI) method based on the equation made by Nieuwolt [8].The THI method produces an index scale to determine the effects and conditions of comfort humans feel based on-air surface temperature and relative humidity in an area.This research was carried out by paying attention to long-term data to obtain index values under climate rules and to provide an overview of the pattern of support for human activities in outdoor tourism activities and nature tourism activities which are very closely related to climate or weather conditions.Short-term weather conditions have an impact on tourists' decisions and experiences [9].This study aims to obtain a comfortable climate pattern in tourism that can support determining the best visit time.For daily activities, it can be considered in the diurnal pattern obtained in calculating the Temperature humidity index (THI), and the comfort level in climatological periodicals.

Location of study
Palabuhanratu is a region located in Sukabumi Regency, West Java Province, Indonesia.Palabuhanratu is the capital for Sukabumi Regency.Pelabuhanratu district is located at coordinates 106° 32' 14.653" E, 6° 58' 54.087" S to 106° 34' 41.972" E, 6° 59' 13.949" S. Palabuhanratu District is bounded on the north by Cikidang District, on the south by Bantagadung District, on the west by Simpenan District, and on the east by Cikakak and Samudra Indonesia Districts [10].

Data
In this study, daily average surface air temperature data were used from the ERA5 analysis for 1991-2020 in Sukabumi Regency, which covers Palabuhanratu District, and dew point temperature data for the same period are used.To obtain relative humidity data, use equation ( 1) using the dew point temperature parameter because RH data is unavailable in the ERA 5 dataset.
ERA5 is an assimilation of various observational data (SYNOP, DRIBU, TEMP, PILOT, and AIRCRAFT-based atmospheric observations) and satellite data and is generated from high-performance computations from the European Center for Medium_range Weather Forecast (ECMWF) and the Copernicus Climate Change Service (C3S) [11] which provides data on an hourly to monthly scale with a spatial resolution of 0.1° x 0.1° which can be downloaded via the Copernicus website (http://www.copernicus.eu/).The average surface temperature data is 2 meters above the land surface.
This temperature data is expressed in units of Kelvin.While THI processing, the temperature must be converted to degrees Celsius.ERA5 data is used because it can properly represent weather patterns common in tropical areas such as Indonesia and reduce rainfall bias compared to the previous product, namely ERA-Interim [12].
In THI weighting, the data needed is surface air temperature and RH.RH data can be derived from the dew point and surface air temperature, as shown in equation (1).

Thermal Comfort based on THI
The Temperature Humidity Index is a parameter measured in degrees Celsius that is related to the level of thermal comfort felt by the human population in a certain area [14].The THI method was first developed by [6] and then modified by [7] for tropical climate conditions.THI is a measure of thermal comfort in a given region which is influenced by temperature and relative humidity factors based on Sugiasih (2013) [15].For this analysis, it is used based on equation (2).THI calculations are carried out separately to produce data that will be processed again with spatial analysis.
The formula used to determine THI is as follows: Where: THI : Temperature Humidity Index T : Temperature (°C) RH : Relative Humidity (%) The thermal comfort criteria based on THI in the tropical climate in Indonesia are divided into four categories namely cold, comfortable, enough comfortable, and discomfort.

Processing and analysis
Data processing is carried out in pre-processing, processing, and post-processing stages.The tools used to assist with the analysis are ArcGis 10.8 (ESRI 2020) and Microsoft Excel.

Relationship analysis between variables
In analyzing the relationship between variables, the linear regression method is used, in which regression is a test tool used to assess the relationship between two or more variables expressed in the form of a relationship/function.The straightforward linear regression equation [16] is as follows: Where: Y : Dependent variable or regression line (response variable) a : constant (intercept) b : the intersection with the vertical axis regression constant (slope) X : independent variable (predictor)

Temperature humidity index analysis
This study's data was processed, the climatic conditions in Palabuhanratu District during 1991-2020 (30 years) can be described by having a minimum air temperature of 17,312°C (further research is needed), maximum air temperature of 33,615°C, average air temperature 24.594°C, average relative humidity 86.522%.The highest air temperature in Palabuhanratu District occurs in May, and the lowest is in December.There was an increase in the value of the THI index that occurred in March-May and August-October.This study found that the increase in the THI index would be in line with the increasimg in air surface temperature, as shown in Figure 2.Where the increase in the THI index starts in February-May and moves down in July.While there was an increase again in August-October.In this study, other climatic parameters were not discussed, which might have triggered the decrease and increase in temperature.The highest THI index value of 24.37°C occurred in May, while the second highest of 24.06°C occurred in October.The lowest THI index value of 23.48°C occurred in August.The highest average temperature is 25.07°C in May, and the lowest is 24.17°C in December.
From figures 2 and 3, it shows the result of the THI analysis: in May, the climatic conditions at the peak of the tourist area's THI index of Palabuhanratu district were in the "comfortable" category, with values ranging from 21 to 24, and it has the second peak in October was in the same category.These monthly thermal comfort values vary and have Bimodal Shoulder peaks [17].The result of the THI index value shows Bimodal Shoulder Peaks, also found in the writings of N.A.I.Hasanah et al. (2020) [18] give an illustration of two peaks in the monthly period.

Spatial analysis and classification of THI
The best interpolation method for surface temperature spatial data can use the IDW interpolation method [19]; with this method, spatial analysis and classification are carried out.Figure 4 carried out a spatial analysis with a large area first to see the classification of the THI index on a large scale based on Nieuwolt (1977) [7].In this case, the analysis begins with the Sukabumi Regency area, and there are three THI classifications are obtained, namely cold, comfortable, and comfortable enough.In Figure 4, It can also be seen that from January to May, the THI index's value started to rise, with a peak in May.
Then the THI index value began to decline from July to September, with only two categories (cold and comfortable).It can be seen that the most comfortable months in the Sukabumi Regency are in July-September.Then there was an increase in the value of the THI index in October, and it started to peak in November.In October-December, in the southern part of Sukabumi Regency, a relatively large portion of the area is comfortable enough.From the figure, it can be seen that the southern region of the Sukabumi Regency is the part that has a sufficiently comfortable classification, while the central part of the Sukabumi Regency tends to be classified as comfortable.Unfortunately, the classification of discomfort was not found in this study.On the other hand, for the Palabuhanratu District, it can be seen from Figure 5 that the pattern is not much different from Sukabumi Regency.But in terms of THI classification, there are only two classifications: most areas are comfortable, and a few others are comfortable.In figure 5, the increase in the value of the THI index began in March and peaked in May.It can be concluded that, for March-May, the Palabuhanratu District area has a THI index that is comfortable enough, or it can be said that it is less comfortable, which is indicated by the increase in air temperature in these months.While quite a few areas are comfortable enough in October, all the other months are in the "comfortable" classification.

Tourism Visiting Time based on THI
According to Goeldner and Ritchie (2006) [20] Geography is a broad scientific discipline that encompasses diverse subjects, making it natural for those studying geography to take an interest in tourism and its spatial components.Geography focuses on the investigation of position, surroundings, climate, scenery, and economic elements.Geography's view of tourism focuses on the areas where visitors congregate, the movements of people generated by the tourism industry, changes in tourism to the interaction between the landscape and the design of tourism facilities, tourism development, physical planning, economic, social, and cultural issues.On the other hand, climate is among the significant natural factors that attract tourists' attention.[21] Tourists generally look for tourism attractions with more comfortable and different climatic conditions compared to the climatic conditions where they live.Thermal comfort can be understood as a mental state indicating contentment with the surrounding thermal conditions.When considering outdoor thermal comfort, it emerges from the impact of the building's structure on the temperature in its vicinity, ultimately leading to the assessment of the environmental thermal comfort value [22].Although there was evidence that microclimate conditions had an impact on tourists' thermal comfort, it was clear that they felt comfortable regardless of the circumstances, demonstrating the importance of taking typical thermal comfort thresholds into account in the tourism industry [23].In terms of determining outdoor activities that are strongly influenced by thermal comfort, it is essential to take notice or give proper consideration to the diurnal variations for THI values that have been obtained, where the time to be avoided is the peak value at 12-13 o'clock (Figure 6).The value of this diurnal variation can be used as a guide in carrying out outdoor activities so that tourism activities become comfortable, these thermal conditions greatly affect tourism activities.This corresponds to thermal comfort-related conditions in subtropical coastal cities based on local climate zones, which can effectively reflect human sense of the thermal environment [24].The annual movement of the THI index value over a period of 30 years has increased, as shown in Figure 7.The highest THI value occurred in 2016, and the lowest THI value occurred in 1999.For 30 years, the maximum value of THI increase in Palabuhanratu District was 0.42 °C.However, this is still lower than the maximum THI increase on Java Island in the study of Kartika et al. (2021) [25], which reached 0.72 °C, and on Sulawesi Island in the study of Marsitha et al. (2019) [26], which reached 0.9 °C over a period of 30 years.While visits can be made throughout the year in the Palabuhanratu District

Figure 2 .
Figure 2. Relationship in each of average air temperature and THI index value in Palabuhanratu District.

Figure 3 .
Figure 3. Relationship in each of relative humidity and THI index value in Palabuhanratu District.

Figure 6 .
Figure 6.Diurnal Variation of THI in Palabuhanratu District