Abstract
As a combination of temperature and humidity, wet-bulb temperature (WBT) is useful for assessing heat stress and its societal and economic impacts. However, spatial and temporal behaviors of summer WBT in China remain poorly understood. In this study, we investigate the dominant spatiotemporal modes of summer (June–July–August) WBT in the mainland of China during 1960–2017 by using empirical orthogonal function (EOF) analysis and reveal their corresponding underlying mechanisms. The leading mode (EOF1) of summer WBT in China shows a nationwide increasing WBT with a stronger magnitude in northern and western than southeastern China. The second mode (EOF2) displays a zonal pattern with anomalously increased WBT in the west and decreased WBT in the east. The third mode (EOF3) shows a meridional feature with the largest WBT trends appearing in the Yangtze River valley. Further examinations suggest that EOF1 exhibits remarkable interdecadal/long-term variations and is likely connected with global warming and the Atlantic Multidecadal Oscillation (AMO), which induce an anomalous anticyclone centering over northern China and covering nearly the whole country. This anticyclone not only plays a key role in the nationwide WBT increases, but also dominates the spatial pattern of EOF1 by modulating relative humidity. EOF2 and EOF3 reflect interannual variations and show significant correlations with the El Niño-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), respectively. A zonal wavelike pattern with troughs over Balkhash and northeastern China, and Mongolia high substantially modulates the water vapor transport in China, thus playing a key role in EOF2. In the case of EOF3, an anomalous anticyclone in the middle-upper troposphere and a shallow intensified cyclone in the lower troposphere collectively format the spatial pattern of EOF3 by inducing significant increases in temperature in central-eastern China and transporting a large amount of water vapor to northeastern China, respectively. These findings are critical to improve our understanding of summer WBT in China and to mitigate the negative effects of heat stress.
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Data availability statement
The daily mean temperature data used in this study are available on the following website: http://data.cma.cn. The daily mean relative humidity data are available from the homogenized relative humidity dataset (ChinaRHv1.0) (http://www.scidb.cn/en/detail?dataSetId=633694461334913025&language=zh_CN&dataSetType=personal). NCEP-NCAR reanalysis dataset, the monthly Extended Reconstructed Sea Surface Temperature version 4, and the monthly precipitation are available from the following websites: https://psl.noaa.gov/data/gridded/data.ncep.reanalysis.pressure.html#, https://psl.noaa.gov/data/gridded/data.noaa.ersst.v5.html, and https://psl.noaa.gov/data/gridded/data.prec.html, respectively. The authors are greatly thankful to three anonymous reviewers for their constructive suggestions and comments that improve our paper.
References
Ahmadalipour A, Moradkhani H (2018) Escalating heat-stress mortality risk due to global warming in the Middle East and North Africa (MENA). Environ Int 117:215–225
Ambaum MHP, Hoskins BJ, Stephenson DB (2002) Arctic oscillation or North Atlantic oscillation? (vol 14, pg 3495, 2001). J Clim 15:553–553
Anderson GB, Bell ML (2011) Heat waves in the United States: mortality risk during heat waves and effect modification by heat wave characteristics in 43 US communities. Environ Health Perspect 119:210–218
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
Byrne MP, O’Gorman PA (2018) Trends in continental temperature and humidity directly linked to ocean warming. Proc Natl Acad Sci 115:4863–4868
Chen M, Xie P, Janowiak JE, Arkin PA (2002) Global land precipitation: a 50-yr monthly analysis based on gauge observations. J Hydrometeorol 3:249–266
Ciais P, Reichstein M, Viovy N, Granier A, Ogée J, Allard V et al (2005) Europe-wide reduction in primary productivity caused by the heat and drought in 2003. Nature 437:529–533
Coffel ED, Horton RM, de Sherbinin A (2018) Temperature and humidity based projections of a rapid rise in global heat stress exposure during the 21st century. Environ Res Lett 13:014001
Coumou D, Rahmstorf S (2012) A decade of weather extremes. Nat Clim Chang 2:491–496
Cowan T, Purich A, Perkins S, Pezza A, Boschat G, Sadler K (2014) More frequent, longer, and hotter heat waves for Australia in the twenty-first century. J Clim 27:5851–5871
Cressman GP (1959) An operational objective analysis system. Mon Weather Rev 87:367–374
Dawson A (2016) eofs: A library for EOF analysis of meteorological, oceanographic, and climate data. J Open Res Softw 4:e14
Deng K, Yang S, Ting M, Zhao P, Wang Z (2019) Dominant modes of China summer heat waves driven by global sea surface temperature and atmospheric internal variability. J Clim 32:3761–3775
Ding Y, Wang S (2001) In introduction to climate and ecological environment in northwest China (pp. 15). Meteorological Press, Beijing
Ding T, Qian WH, Yan ZW (2010) Changes in hot days and heat waves in China during 1961–2007. Int J Climatol 30:1452–1462
Dunne JP, Stouffer RJ, John JG (2013) Reductions in labour capacity from heat stress under climate warming. Nat Clim Chang 3:563–566
Enfield DB, Mestas-Nunez AM, Trimble PJ (2001) The Atlantic multidecadal oscillation and its relation to rainfall and river flows in the continental US. Geophys Res Lett 28:2077–2080
Fischer EM, Schär C (2010) Consistent geographical patterns of changes in high-impact European heatwaves. Nat Geosci 3:398–403
Folland C, Parker D (1990) Observed variations of sea surface temperature. In: Climate-ocean interaction. Springer, pp. 21–52.
Freychet N, Tett SFB, Hegerl GC, Wang J (2018) Central-Eastern China persistent heat waves: evaluation of the AMIP models. J Clim 31:3609–3624
Freychet N, Tett SFB, Yan Z, Li Z (2020) Underestimated change of wet-bulb temperatures over East and South China. Geophys Res Lett 47:e2019GL086140
Gao T, Luo M, Lau N-C, Chan TO (2020) Spatially Distinct Effects of Two El Niño Types on Summer Heat Extremes in China. Geophys Res Lett 47(6):e2020GL086982
Hannachi A, Jolliffe IT, Stephenson DB (2007) Empirical orthogonal functions and related techniques in atmospheric science: A review. Int J Climatol 27:1119–1152
Hirschi M, Seneviratne SI, Alexandrov V, Boberg F, Boroneant C, Christensen OB et al (2011) Observational evidence for soil-moisture impact on hot extremes in southeastern Europe. Nat Geosci 4:17–21
Houghton DD (1985) Handbook of applied meteorology. Wiley
Hu LS, Huang G, Qu X (2017) Spatial and temporal features of summer extreme temperature over China during 1960–2013. Theoret Appl Climatol 128:821–833
Huang B, Thorne PW, Banzon VF, Boyer T, Chepurin G, Lawrimore JH et al (2017) Extended reconstructed sea surface temperature, version 5 (ERSSTv5): upgrades, validations, and intercomparisons. J Clim 30:8179–8205
Im ES, Pal JS, Eltahir EAB (2017) Deadly heat waves projected in the densely populated agricultural regions of South Asia. Sci Adv. https://doi.org/10.1126/sciadv.1603322
IPCC (2021) Climate change 2021: the physical science basis. In: Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press
Kalkstein LS, Davis RE (1989) Weather and human mortality: an evaluation of demographic and interregional responses in the United States. Ann Assoc Am Geogr 79:44–64
Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L et al (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteor Soc 77:437–471
Kang S, Eltahir EAB (2018) North China Plain threatened by deadly heatwaves due to climate change and irrigation. Nat Commun. https://doi.org/10.1038/s41467-018-05252-y
Kerr RA (2000) A North Atlantic climate pacemaker for the centuries. Science 288:1984–1985
Lau NC, Nath MJ (2014) Model simulation and projection of european heat waves in present-day and future climates. J Clim 27:3713–3730
Li SL, Perlwitz J, Quan XW, Hoerling MP (2008) Modelling the influence of North Atlantic multidecadal warmth on the Indian summer rainfall. Geophys Res Lett. https://doi.org/10.1029/2007GL032901
Li S, Wang Y, Gao Y (2009) A review of the researches on the Atlantic Multidecadal Oscillation (AMO) and its climate influence. Trans Atmos Sci 32:458–465
Li B, Chen Y, Shi X (2012) Why does the temperature rise faster in the arid region of northwest China? J Geophys Res Atmos. https://doi.org/10.1029/2012JD017953
Li Q, Huang J, Jiang Z, Zhou L, Chu P, Hu K (2014) Detection of urbanization signals in extreme winter minimum temperature changes over Northern China. Clim Change 122:595–608
Li C, Zhang X, Zwiers F, Fang Y, Michalak AM (2017) Recent very hot summers in northern hemispheric land areas measured by wet bulb globe temperature will be the norm within 20 years. Earth’s Fut 5:1203–1216
Li JP, Zheng F, Sun C, Feng J, Wang J (2019) Pathways of influence of the northern hemisphere mid-high latitudes on East Asian climate: a review. Adv Atmos Sci 36:902–921
Li C, Sun Y, Zwiers F, Wang D, Zhang X, Chen G et al (2020a) Rapid warming in summer wet bulb globe temperature in China with human-induced climate change. J Clim 33:5697–5711
Li Z, Yan Z, Zhu Y, Freychet N, Tett S (2020b) Homogenized daily relative humidity series in China during 1960–2017. Adv Atmos Sci 37:318–327
Lin L, Chen C, Luo M (2018) Impacts of El Niño-Southern Oscillation on heat waves in the Indochina peninsula. Atmos Sci Lett 19(11):e856
Lin LJ, Ge EJ, Liu XP, Liao WL, Luo M (2018) Urbanization effects on heat waves in Fujian Province. Southeast China Atmos Res 210:123–132
Liu XC, Tang QH, Zhang XJ, Sun SA (2018) Projected changes in extreme high temperature and heat stress in China. J Meteorol Res 32:351–366
Luo M, Lau NC (2017) Heat waves in Southern China: Synoptic behavior, long-term change, and urbanization effects. J Clim 30:703–720
Luo M, Lau NC (2018) Increasing heat stress in urban areas of eastern China: acceleration by urbanization. Geophys Res Lett 45:13060–13069
Luo M, Lau N-C (2019a) Characteristics of summer heat stress in China during 1979–2014: climatology and long-term trends. Clim Dyn 53:5375–5388
Luo M, Lau N-C (2019b) Amplifying effect of ENSO on heat waves in China. Clim Dyn 52(5-6):3277–3289
Luo M, Lau N-C (2021) Increasing human-perceived heat stress risks exacerbated by urbanization in China: a comparative study based on multiple metrics. Earth’s Fut 9(7):e2020EF001848
Luo M, Ning GC, Xu F, Wang SG, Liu Z, Yang YJ (2020) Observed heatwave changes in arid northwest China: physical mechanism and long-term trend. Atmos Res 242:105009
Monteiro JM, Caballero R (2019) Characterization of extreme wet-bulb temperature events in southern Pakistan. Geophys Res Lett 46:10659–10668
North GR, Bell TL, Cahalan RF, Moeng FJ (1982) Sampling errors in the estimation of empirical orthogonal functions. Mon Weather Rev 110:699–706
Pal JS, Eltahir EAB (2016) Future temperature in southwest Asia projected to exceed a threshold for human adaptability. Nat Clim Chang 6:197–200
Qian W (2017) Temporal climatology and anomalous weather analysis. Springer, Berlin
Qian WH, Yu TT, Du J (2016) A unified approach to trace surface heat and cold events by using height anomaly. Clim Dyn 46:1647–1664
Raymond C, Singh D, Horton R (2017) Spatiotemporal patterns and synoptics of extreme wet-bulb temperature in the contiguous United States. J Geophys Res Atmos 122:13108–13124
Ren G, Guan Z, Shao X, Gong DY (2011) Changes in climatic extremes over mainland China. Clim Res 50:105–111
Ren GY, Ding YH, Tang GL (2017) An overview of mainland china temperature change research. J Meteorol Res 31:3–16
Sanz-Barbero B, Linares C, Vives-Cases C, González JL, López-Ossorio JJ, Díaz J (2018) Heat wave and the risk of intimate partner violence. Sci Total Environ 644:413–419
Simister J, Cooper C (2005) Thermal stress in the USA: effects on violence and on employee behaviour. Stress Health 21:3–15
Stefanon M, Drobinski P, D’Andrea F, Lebeaupin-Brossier C, Bastin S (2014) Soil moisture-temperature feedbacks at meso-scale during summer heat waves over Western Europe. Clim Dyn 42:1309–1324
Stull R (2011) Wet-bulb temperature from relative humidity and air temperature. J Appl Meteorol Climatol 50:2267–2269
Su Q, Dong B (2019) Projected near-term changes in three types of heat waves over China under RCP4.5. Clim Dyn 53(7–8):3751–3769
Suarez-Gutierrez L, Müller WA, Li C, Marotzke J (2020). Hotspots of extreme heat under global warming. Clim Dyn 55(3-4):429-447
Sutton RT, Hodson DLR (2007) Climate response to basin-scale warming and cooling of the North Atlantic Ocean. J Clim 20:891–907
Wang YM, Li SL, Luo DH (2009) Seasonal response of Asian monsoonal climate to the Atlantic Multidecadal Oscillation. J Geophys Res Atmos. https://doi.org/10.1029/2008JD010929
Wang WW, Zhou W, Wang X, Fong SK, Leong KC (2013) Summer high temperature extremes in Southeast China associated with the East Asian jet stream and circumglobal teleconnection. J Gerontol Ser A Biol Med Sci 118:8306–8319
Wang WW, Zhou W, Li XZ, Wang X, Wang DX (2016) Synoptic-scale characteristics and atmospheric controls of summer heat waves in China. Clim Dyn 46:2923–2941
Wang P, Tang J, Sun X, Wang S, Wu J, Dong X et al (2017) Heatwaves in China: definitions, leading patterns and connections to large-scale atmospheric circulation and SSTs. J Geophys Res Atmos 122:180
Wang P, Leung LR, Lu J, Song F, Tang J (2019) Extreme wet-bulb temperatures in China: the significant role of moisture. J Geophys Res Atmos 124:11944–11960
Wang P, Yang Y, Tang J, Leung LR, Liao H (2021) Intensified humid heat events under global warming. Geophys Res Lett 48:e2020GL091462
Wang X, Ma Y, B. Z, Wang H, Zhang N (1999) Research on water vapour transport passage way of "96·7" exceptional torrential rain in Xinjiang. Desert and OasisMeteorology 22: 5–9
Wang X-R, Xu X-D, Wang W-G (2007) Charateristic of spatial transportation of water vapor for northwest China′ s rainfall in spring and summer [J]. Plateau Meteorol 4
Willett KM, Sherwood S (2012) Exceedance of heat index thresholds for 15 regions under a warming climate using the wet-bulb globe temperature. Int J Climatol 32:161–177
Wuebbles D, Meehl G, Hayhoe K, Karl TR, Kunkel K, Santer B et al (2014) CMIP5 climate model analyses: climate extremes in the United States. Bull Am Meteor Soc 95:571–583
Xu W, Li Q, Wang XL, Yang S, Cao L, Feng Y (2013) Homogenization of Chinese daily surface air temperatures and analysis of trends in the extreme temperature indices. J Geophys Res Atmos 118:9708–9720
Yang X, Tian Z, Sun LX, Chen BD, Tubiello FN, Xu YL (2017) The impacts of increased heat stress events on wheat yield under climate change in China. Clim Change 140:605–620
You Q, Jiang Z, Kong L, Wu Z, Bao Y, Kang S et al (2017) A comparison of heat wave climatologies and trends in China based on multiple definitions. Clim Dyn 48:3975–3989
Yuan Q, Wang GJ, Zhu CX, Lou D, Hagan DFT, Ma XW et al (2011) Coupling of soil moisture and air temperature from multiyear data during 1980–2013 over China. Atmosphere. https://doi.org/10.3390/atmos11010025
Zhai PM, Pan XH (2003) Trends in temperature extremes during 1951–1999 in China. Geophys Res Lett. https://doi.org/10.1029/2003GL018004
Zhang GW, Zeng G, Li C, Yang XY (2020) Impact of PDO and AMO on interdecadal variability in extreme high temperatures in North China over the most recent 40-year period. Clim Dyn 54:3003–3020
Acknowledgements
This study is funded by the National Natural Science Foundation of China (No. 41871029 and 91644226) and the National Key R&D Program of China (2019YFC1510400). The appointment of M. Luo at Sun Yat-sen University is partially supported by the Pearl River Talent Plan of Guangdong Province, China (2017GC010634). Z. Liu is supported by the Institute for Basic Science (IBS), Republic of Korea (IBS-R028-D1).
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Ning, G., Luo, M., Wang, S. et al. Dominant modes of summer wet bulb temperature in China. Clim Dyn 59, 1473–1488 (2022). https://doi.org/10.1007/s00382-021-06051-w
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DOI: https://doi.org/10.1007/s00382-021-06051-w
Keywords
- Wet-bulb temperature
- Heat stress
- Dominant modes
- Natural climate variability
- Wavelike pattern
- Empirical orthogonal function