Abstract
Air temperature and vapor pressure are both considered important factors affecting thermal comfort during summer. However, their variability contributes differently to the comfort level. Based on daily observations over a 56-year period (1961–2016), this study used the Mann–Kendall (MK) test and Theil–Sen’s estimator to examine the trends in summer air temperature and vapor pressure for 648 stations across China. Geographic information system (GIS) grouping analysis was applied to understand the spatial pattern of their changes. Further, based on the assumption of constant wind speed and mean radiant temperature equal to air temperature, the responses of summer daily mean Universal Thermal Comfort Index (UTCI) and the number of summer days with “no thermal stress” to changes in summer air temperature and vapor pressure were investigated. Sensitivity analysis was carried out to identify the areas where UTCI is more sensitive to air temperature and vapor pressure changes. Comparison of the contributions of air temperature and vapor pressure was made to understand the different roles they have played in the changes of UTCI. The results show that approximately 70% of the stations show significant increases in summer air temperature and 33% of the stations show upward trends in summer vapor pressure. As a consequence of the increasing UTCI throughout most of the country, the number of “no thermal stress” days dropped sharply in many areas with an exception of the Tibetan Plateau where this number rose by an average of 0.05 days per year during the study period. Sensitivity analysis shows that summer UTCI is much more sensitive to a unit change of air temperature than that of vapor pressure. However, due to its substantial changes in some regions, including Northwest and Northeast China, the middle and lower reaches of Yangtze River, vapor pressure also played an important role in either intensifying or mitigating the thermal stress in summer.
Similar content being viewed by others
References
Ajaaj AA, Mishra AK, Khan AA (2018) Urban and peri-urban precipitation and air temperature trends in mega cities of the world using multiple trend analysis methods. Theor Appl Climatol 132:403–418
American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) (2004) Thermal environmental conditions for human occupancy standard. ASHRAE Standard. ASHRAE, Atalanta, pp 55–2004
Barreca AI (2012) Climate change, humidity, and mortality in the United States. J Environ Econ Manag 63(1):19–34
Barreca AI, Shimshack JP (2012) Absolute humidity, temperature, and influenza mortality: 30 years of county-level evidence from the United States. Am J Epidemiol 176(Suppl 7):S114–S122
Bazrafshan J (2017) Effect of air temperature on historical trend of long-term droughts in different climates of Iran. Water Resour Manag 31(14):4683–4698
Blazejczyk K, Epstein Y, Jendritzky G, Staiger H, Tinz B (2012) Comparison of UTCI to selected thermal indices. Int J Biometeorol 56(3):515–535
Błażejczyk K, Jendritzky G, Bröde P (2013) An introduction to the Universal Thermal Climate Index (UTCI). Geogr Pol 86(1):5–10
Bröde P, Fiala D, Błażejczyk K, Holmér I, Jendritzky G, Kampmann B, Tinz B, Havenith G (2012) Deriving the operational procedure for the Universal Thermal Climate Index (UTCI). Int J Biometeorol 56(3):481–494
Byrne MP, O’Gorman PA (2013) Land-ocean warming contrast over a wide range of climates: convective quasi-equilibrium theory and idealized simulations. J Clim 26:4000–4016
Byrne MP, O’Gorman PA (2016) Understanding decreases in land relative humidity with global warming: conceptual model and GCM simulations. J Clim 29:9045–9061
Calinski T, Harabasz J (1974) A dendrite method for cluster analysis. Commun Stat Theory Methods 3(1):1–27
Darshana PA, Pandey RP (2013) Analyzing trends in reference evapotranspiration and weather variables in the Tons River Basin in Central India. Stoch Env Res Risk A 27(6):1407–1421
de Freitas CR, Grigorieva EA (2015) A comprehensive catalogue and classification of human thermal climate indices. Int J Biometeorol 59(1):109–120
Dessler AE, Sherwood SC (2009) A matter of humidity. Science 323(5917):1020–1021
Dessler AE, Zhang Z, Yang P (2008) Water-vapor climate feedback inferred from climate fluctuations, 2003–2008. Geophys Res Lett 35(20):L20704
Environmental Systems Research Institute (ESRI) (2015) ArcGIS 10.3.1 for Desktop Online Help. ESRI Inc, Redlands
Fernandes R, Leblanc SG (2005) Parametric (modified least squares) and non-parametric (Theil–Sen) linear regressions for predicting biophysical parameters in the presence of measurement errors. Remote Sens Environ 95:303–316
Fiala D, Havenith G, Bröde P, Kampmann B, Jendritzky G (2012) UTCI-Fiala multi-node model of human heat transfer and temperature regulation. Int J Biometeorol 56(3):429–441
Giannopoulou K, Livada I, Santamouris M et al (2013) The influence of air temperature and humidity on human thermal comfort over the greater Athens area. Sustain Cities Soc 10:184–194
Hirsch RM, Slack JR, Smith RA (1982) Techniques of trend analysis for monthly water quality data. Water Resour Res 18(1):107–121
Jendritzky G, De Dear R, Havenith G (2012) Why another thermal index? Int J Biometeorol 56(3):421–428
Kendall MG (1975) Rank correlation methods, 4th edn. Charles Griffin, London
Kolendowicz L, Półrolniczak M, Szyga-Pluta K, Bednorz E (2017) Human-biometeorological conditions in the southern Baltic coast based on the universal thermal climate index (UTCI). Theor Appl Climatol 134:363–379. https://doi.org/10.1007/s00704-017-2279-2
Lenhart T, Eckhardt K, Fohrer N, Frede HG (2002) Comparison of two different approaches of sensitivity analysis. Phys Chem Earth 27:645–654
Mann HB (1945) Non-parametric tests against trend. Econometrica 13:245–259
Matzarakis A, Amelung B (2008) Physiologically equivalent temperature as indicator for impacts of climate change on thermal comfort of humans. In: Thomson MC, Garcia-Herrera R, Beniston M (eds) Seasonal forecasts, climatic change and human health. Advances in global change research 30, Springer-Sciences and Business Media, 161–172
Matzarakis A, Endler C (2010) Climate change and thermal bioclimate in cities: impacts and options for adaptation in Freiburg, Germany. Int J Biometeorol 54(4):479–483
Mosaedi A, Sough MG, Sadeghi SH et al (2017) Sensitivity analysis of monthly reference crop evapotranspiration trends in Iran: a qualitative approach. Theor Appl Climatol 128:857–873
Pappenberger F, Jendritzky G, Staiger H, Dutra E, di Giuseppe F, Richardson DS, Cloke HL (2015) Global forecasting of thermal health hazards: the skill of probabilistic predictions of the Universal Thermal Climate Index (UTCI). Int J Biometeorol 59(3):311–323
Prăvălie R, Bandoc G, Patriche C, Tomescu M (2017) Spatio-temporal trends of mean air temperature during 1961–2009 and impacts on crop (maize) yields in the most important agricultural region of Romania. Stoch Env Res Risk A 31(8):1923–1939
Provençal S, Bergeron O, Leduc R, Barrette N (2016) Thermal comfort in Quebec City, Canada: sensitivity analysis of the UTCI and other popular thermal comfort indices in a mid-latitude continental city. Int J Biometeorol 60(4):591–603
Rozbicka K, Rozbicki T (2017) Variability of UTCI index in South Warsaw depending on atmospheric circulation. Theor Appl Climatol 133:511–520
Sen PK (1968) Estimates of the regression coefficient based on Kendall’s tau. J Am Stat Assoc 63(324):1379–1389
Singh D, Jain SK, Gupta RD (2015) Trend in observed and projected maximum and minimum temperature over N-W Himalayan basin. J Mt Sci 12(2):417–433
Sutton RT, Dong B, Gregory JM (2007) Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations. Geophys Res Lett 34:L02701. https://doi.org/10.1029/2006GL028164
Theil H (1950) A rank-invariant method of linear and polynomial regression analysis, I. Proc Kon Ned Akad van Wetensch A53:386–392
Walikewitz N, Jänicke B, Langner M, Endlicher W (2018) Assessment of indoor heat stress variability in summer and during heat warnings: a case study using the UTCI in Berlin, Germany. Int J Biometeorol 62(1):29–42
Funding
This research was supported by the Natural Science Foundation of Jiangsu Province (Grant No. BK20160953) and the Overseas Study Program for Outstanding Young and Middle-aged Professors in Jiangsu Province.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Yan, Y., Wang, D., Yue, S. et al. Trends in summer air temperature and vapor pressure and their impacts on thermal comfort in China. Theor Appl Climatol 138, 1445–1456 (2019). https://doi.org/10.1007/s00704-019-02909-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00704-019-02909-6