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CMIP6 Projections Of Changes In Different Types Of Drought In China In The 21st Centur

Posted on:2024-07-28Degree:MasterType:Thesis
Country:ChinaCandidate:Q X ChenFull Text:PDF
GTID:2530307106972469Subject:Science of meteorology
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Model simulations show that drought may become more severe and widespread due to the global warming.However,the comprehensive analysis of the changes in different types of drought indices and the relative contributions of key meteorological factors to the model-projected drought changes over China have not yet been examined in detail.We evaluated the performance of phase 6 of the Coupled Model Intercomparison Project(CMIP6)model simulation of temperature,precipitation and the self-calibrated Palmer Drought Severity Index with Penman-Monteith potential evapotranspiration(sc PDSIpm)in terms of climatological spatial distribution and interannual variability in China,and selected the preferred models set.Then,we used this set to discuss the future drought changes in China under SSP2-4.5 and SSP5-8.5 scenarios based on five indices: the top-10-cm soil moisture,the total soil moisture,surface runoff,total runoff,and sc PDSIpm.Finally,we investigated the contributions based on sc PDSIpm from precipitation(P),near-surface air temperature and specific humidity [Δ(T+q)],net surface longwave radiation(LW),net surface shortwave radiation(SW),and wind speed(WS)to future drought changes.The main conclusions are as follows:(1)Compared with CN05.1 observation and CRU reanalysis data,the performance of CMIP6 simulation for temperature,precipitation,and sc PDSIpm in China gradually decreases in terms of climatological spatial distribution and interannual variability.Select 10 modes that simulate sc PDSIpm well and form a preferred set for estimating.(2)According to the Bayesian model averaging,the climate states of these five drought indices decrease in the southeast region and generally increase in the western region from1985-2014 to 2070-2099 under two scenarios.The drought frequency based on most drought indices increases in the southern and northeastern regions,while decreases in the northwestern and northern regions.The duration of drought based on most drought indices increases in most parts of China,except for decreasing in North China,central northwest,and western Qinghai Tibet,with the most significant increase in drought duration based on total soil moisture.The drought area based on surface soil moisture,total soil moisture and sc PDSIpm increases in China,while the drought area based on surface runoff and total runoff increases slightly in the Qinghai Tibet Plateau region and decreases in other regions.(3)Through attribution analysis of sc PDSIpm changes,it is found that the drying changes of sc PDSIpm in southeastern China are mainly attributed to surface warming and an increased near-surface vapor pressure deficit(VPD).The changes in wetting over northern China mostly result from increased precipitation.The flattening of the PDFs mainly results from the increase in precipitation,whereas the mean shift in the PDFs(toward drier conditions)is attributed to surface warming and the increased VPD.The largest changes both in drought frequency,duration and area are attributed to surface warming and an increased VPD.
Keywords/Search Tags:drought change, Palmer Drought Severity Index, attribution
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