Climate Comfort Period In Chinese Mainland: Its Spatial Evolution And Prediction

The basic research idea of climate comfort period is to quantify the length of climate comfortable time and its seasonal distribution by human thermal climate indices, which is of great significance for architectural design, human health and many other fields, especially for the formation of seasonal tourist flow and development of vacation destination. For almost a century, global warming has become an indisputable scientific consensus and the difference of regional climate response has formed. This objectively causes diverse changes of climate comfort period in different regions. Particularly in China, due to complex geographical condition and various climate types, the climate change impacts are good and bad in different regions or aspects. Therefore, nationwide research on spatial distribution and evolvement rule of climate comfort period is necessary to provide a basic knowledge about man-land relationship for regional response under global climate change, and then provide a scientific basis for human settlements construction and human activity adaption.First, this paper detailed combed the development of human thermal climate indices. Result indicates that empirical model is the most widely used in practical application to evaluate climate comfort. Based on simple measurement device in the early days, empirical indices experienced a development course from multi-factor modeling to multi-model combination, realized the evolution from specific environment evaluation to universal application. Considering certain standard, temperature-humidity index (THI) and wind effect index (WEI) were selected to calculate climate comfort period in Chinese mainland based on daily average meteorological data (air air temperature, wind speed, relative humidity and sunshine duration, etc.) of 775 weather stations from 1961 to 2010. Two methods were used to analyze the change trend of climate comfort period during the past 50 years. Results show that:1) Distribution of climate comfort period in Chinese mainland has significantly regional and seasonal differences. The annual average climate comfort period are 71.3 days with the distribution characteristic that comfort period in southeast are more than the northwest. A main contour line of national annual average approximately matches the Hu’s line. Climate comfort period in summer are the most among all seasons, taking up half the annual value. In spring and fall, comfort period are 18.0 and 16.5 days respectively. In winter, climate comfort period are the shortest that national average is less than 2 days.2) In the past 50 years, annual average of comfort period has increased in most parts of Chinese mainland, except for Sinkiang and Hainan Province etc. It also generally increased in spring and autumn. Change in summer was that comfort period in northwest inland and eastern coastal increased, other regions decreased. And in winter, comfort period in south China increased while north China decreased.Furthermore, this paper also predicted the variation trend of future climate comfort period and its spatial pattern by the historical data mining. Summary of predict method is establishing mapping relation between historical air temperature variation and comfort period variation, and then predicting the future variation of climate comfort period by the future air temperature change value. Prediction result shows that:By the middle of the 21st century, climate comfort period in summer obviously decreased, while comfort period in other seasons as well as the annual average value increase in various degrees as a result from air temperature increase further.