Introduction

Thermal comfort conditions are one of the important factors in determining the tourism capacity of different regions, because changes in climatic elements can affect the appropriate time and place for outdoor tourism activities. The aim of this study is to evaluate the thermal comfort conditions and determine the climatic tourism calendar in Duhok province in northern Iraq using PET, UTCI and TCI bioclimatic indices. Duhok province in northern Iraq is one of the regions that has a high capacity for tourism development due to its natural and geographical characteristics (Mohammed, 2015). The presence of mountain ranges, valleys, natural areas, altitude diversity and natural landscapes has made this province one of the potential tourism destinations. However, the topographic diversity of the province has caused significant differences in the climatic conditions of its different regions. The mountainous parts, highlands and lowlands of the province may have completely different conditions in terms of thermal comfort at a given time. Therefore, providing a fixed tourism calendar for the entire province without considering the spatial variations of climatic conditions cannot meet the needs of tourism planning.



Materials and Methods

In this study, the data used are entirely of the climatic and meteorological type and have been used to analyze thermal comfort conditions and compile a tourism calendar in Dohuk province. These data include a set of main climatic variables that play a direct or indirect role in determining the tourism climate. The main variables used in this study include average air temperature, relative humidity, precipitation, wind speed, and solar radiation on a monthly scale in the period 2000-2025. These elements are known as basic variables in tourism climate studies, and their combination allows the calculation of bioclimatic indices and the assessment of human thermal comfort conditions. The climate data used were extracted from meteorological stations in Duhok province, NOAA global climate databases, and ERA5 reanalysis data. In this study, a set of bioclimatic and thermal comfort indices were used to assess tourism climate conditions and determine suitable periods for tourism activities in Duhok province. These indices are used to convert raw climate data into human-interpretable values and allow for a combined analysis of the effect of different atmospheric elements on human thermal comfort.



Results and Discussion

The assessment of the climatic comfort of tourism in Duhok province based on TCI, UTCI and PET indices showed that the climatic conditions of this region have clear seasonal changes and the favorable period of tourism is mainly concentrated in the middle months of spring and autumn. The results of this study showed that the months of April, May, September and October are most consistent with thermal comfort conditions, while the winter period is affected by cold stress and the peak summer period is affected by increased heat stress. According to the results of the UTCI index, the minimum thermal values were observed in the winter months and the prevailing conditions in this period were cold stress. This situation is consistent with the findings of studies conducted in mountainous areas and similar latitudes, because the decrease in air temperature, the increase in the effect of cold wind and the decrease in the energy received by the earth's surface cause a decrease in thermal comfort indices. In Duhok province, these conditions were observed especially in the months of January, February and December, which indicates the relative limitation of this period for outdoor tourism. In contrast, the gradual increase in UTCI and PET values from March to July indicates a transition from cold to comfort and then relative heat. The maximum values of these two indices were observed in July, which indicates the peak of the warm conditions of the year. This result is consistent with studies conducted in Mediterranean regions, such as research related to the evaluation of thermal indices in cities with hot and arid or semi-arid climates; because in these regions, summer is usually accompanied by an increase in radiant temperature, a decrease in thermal comfort and an increase in the likelihood of heat stress.

The results of the TCI maps showed that the northern and highlands of the province, especially the Zakho and Al-Amadiyah regions, have a greater number of suitable months than the southern regions. This is consistent with the results of studies that have emphasized the role of altitude and topography in modulating thermal conditions. Altitude reduces air temperature, changes radiation patterns and creates different thermal conditions compared to low-lying areas; therefore, mountainous areas can provide more favorable conditions for tourism even in the hot season. The results regarding the number of suitable months for tourism also showed that parts of Dohuk province are capable of having a longer tourism season. This is consistent with tourism climate studies in other regions that have shown that the temporal distribution of tourism is not only dependent on average temperature, but is a combination of thermal and geographical factors. In other words, a region may have suitable thermal conditions but not provide optimal thermal comfort due to strong radiation, unfavorable wind, or high humidity.

Comparing the performance of the two indices PET and UTCI in this study showed that both indices show similar annual trends, but PET shows changes in thermal conditions with a greater emphasis on human physiological response. This has also been reported in previous studies; because PET is designed based on the concept of physiological equivalent temperature and considers the combined effect of environmental variables and human characteristics in assessing thermal comfort. Therefore, the simultaneous use of PET and UTCI can provide a more accurate picture of tourist comfort conditions. The findings of this study show that tourism planning in Duhok province should be based on the climatic calendar. The period from April to May and also from September to October can be introduced as the main seasons for the development of natural, mountain and cultural tourism, because during this period there is the greatest correspondence between climatic conditions and the comfort needs of tourists. The results of this study show that Duhok province has a significant capacity for the development of climate-based tourism due to its topographic and climatic diversity. The use of bioclimatic indices such as TCI, PET and UTCI can be a suitable tool for determining tourism seasons, destination management and increasing thermal satisfaction of tourists in this region. Tourism climate indices have been developed primarily for this purpose, namely, converting climate information into a decision-making tool in tourism planning.



Conclusion

The results showed that thermal comfort conditions in Duhok province have significant spatial and temporal variations, and these variations are strongly influenced by the climatic characteristics, altitude, and topographic structure of the region. The spatial analysis of the PET index showed that Duhok province has a distinct thermal gradient; such that lower-elevation areas, especially the northwestern parts of the province, experience higher PET values and consequently warmer conditions, while the high-altitude and mountainous areas of the southeast and east have lower PET values and cooler conditions due to the temperature modulation caused by altitude. This pattern indicates the essential role of topography in controlling the spatial distribution of thermal comfort and creating climatic differences at the local scale. The examination of monthly changes in PET and UTCI showed that thermal comfort in Duhok province follows a distinct seasonal cycle. In the winter months, the sharp decrease in the values of these indices causes the prevailing cold stress conditions and creates limitations for outdoor tourism activities. With the onset of spring, thermal conditions improve rapidly and the months of April and May show the most suitable comfort conditions. In contrast, summer is accompanied by an increase in PET and UTCI values; such that the months of July and August experience the highest heat stress of the year, although these conditions remain tolerable in parts of the highlands of the province. With the onset of autumn, the decrease in temperature causes the return of favorable conditions and September and October are again recognized as suitable tourism periods. The results of the tourism calendar based on the TCI index also confirmed this pattern and showed that the highest climatic tourism capacity of Duhok province is concentrated in the transitional seasons of spring and autumn. According to this index, the months of April, May, September and October have the highest climatic compatibility for outdoor tourism activities. Among these months, May and September are introduced as the most suitable periods for climate tourism in the province due to the simultaneous placement of PET and UTCI in the optimal comfort range.

Analysis of the number of suitable months for tourism also showed that the climate capacity for tourism is not uniform across the province. High and mountainous areas, especially parts of Al-Amadiyah and the central-eastern regions of the province, have a longer period suitable for tourism, while lower-altitude areas experience a more limited period of comfort due to increased heat stress in summer and colder conditions in winter. Therefore, the spatial distribution of climate tourism in Duhok province is directly related to topographic features and microclimatic conditions.

The findings of this study show that Duhok province has a significant capacity for developing climate tourism, but optimal utilization of this capacity requires temporal and spatial planning appropriate to the thermal conditions of the region. Based on the results, spring and autumn seasons, especially May and September, are considered the most suitable periods for the development of outdoor tourism activities, while winter due to cold stress and peak summer due to increased heat stress should be considered with more restrictions in tourism planning. These results can be used as a scientific basis for tourism management, choosing the right time to hold outdoor events, and sustainable development of climate tourism in Dohuk province.