Spatiotemporal heterogeneity in precipitation and moisture transport over China and their connections with anthropogenic emissions and natural variability

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dc.contributor.advisorHuang, Gordon
dc.contributor.authorLu, Chen
dc.contributor.committeememberZhu, Hua
dc.contributor.committeememberNg, Kelvin Tsun Wai
dc.contributor.committeememberDeng, Dianliang
dc.contributor.externalexaminerChen, Zhi
dc.date.accessioned2023-07-17T16:52:30Z
dc.date.available2023-07-17T16:52:30Z
dc.date.issued2022-09
dc.descriptionA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Environmental Systems Engineering, University of Regina. xxxi, 236 p.en_US
dc.description.abstractIn this dissertation research, the following scientific questions are explored: (i) Has the probability distribution of precipitation over China undergone variations since the midtwentieth century? (ii) How are the above changes related to the modes of climate variability? (iii) Can these changes be attributed to anthropogenic behaviors? (iv) What are the mechanisms for these changes in terms of moisture transport and recycling? Specifically, through quantile regression, the quantile trends in monthly precipitation anomalies over China, as well as the individual and combined quantile effects of teleconnection patterns, are examined. The results show that the quantile trends exhibit apparent seasonal variations, with a greater number of stations showing trends in winter, and larger average magnitudes of trends at nearly all quantile levels in summer. The effects of El Niño–Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO) exhibit evident variations with respect to the quantile level. Spatial clusters are subsequently identified based on the quantile trends, and the individual and combined effects from the teleconnection patterns are further investigated from the perspective of moisture budget. Seven spatial clusters with distinct seasonal quantile trends can be identified; three of them are located in southeastern China and are characterized by increasing trends in summer and winter precipitation. Summer precipitation over this region is positively influenced by ENSO and negatively influenced by NAO, with the former affecting both the dynamic and thermodynamic components of vertically integrated moisture divergence and the latter affecting only the dynamic component. The interaction effect of ENSO and NAO on summer precipitation anomalies in extremely-wetter-than-normal months is statistically significant. The influences of anthropogenic greenhouse gas and aerosol emissions on the probability distribution of daily precipitation over China are explored through a formal detection and attribution analysis. It is found that the increasing trends in winter precipitation at high and extremely high quantile levels, as well as that in spring precipitation at all quantile levels, can be attributed to the effects of historical (ALL) or anthropogenic (ANT) forcing. The effect of anthropogenic greenhouse gas forcing (GHG) is evident over the domain, to which the increasing precipitation trends at all quantile levels in all seasons can be attributed; this effect can be separated from that of anthropogenic aerosol forcing (AER) for winter precipitation trends at high and extremely high quantile levels, and for spring, summer, and autumn trends at low quantile levels. Through integrating detection and attribution analysis and moisture tracking into one framework, the anthropogenic influence on the moisture source-receptor relationship over China is investigated. The subdomains of China can be grouped into 3 categories according to the major moisture sources, which are regions mainly dependent on (a) oceanic sources, (b) external terrestrial sources, and (c) local recycling. It is found that the GHG forcing, in general, favor reduced moisture contributions from oceanic sources to the west of the domain in winter and enhanced those from the ones to the east of the domain in both winter and summer for regions in the first category. Under the GHG scenario, moisture contributions from external terrestrial sources are reduced in summer for subdomains in the first category and show a shift from the north to the south for other regions; under the AER scenario, the opposite case can be observed. Local recycling is generally enhanced in summer under both GHG and AER scenarios, with an exception for the regions in the first category, which exhibit reduced local recycling under the GHG forcing.en_US
dc.description.authorstatusStudenten
dc.description.peerreviewyesen
dc.identifier.tcnumberTC-SRU-16032
dc.identifier.thesisurlhttps://ourspace.uregina.ca/bitstream/handle/10294/16032/LU%2cChen_PhD_EVSE_Thesis_2023Spring.pdf
dc.identifier.urihttps://hdl.handle.net/10294/16032
dc.language.isoenen_US
dc.publisherFaculty of Graduate Studies and Research, University of Reginaen_US
dc.titleSpatiotemporal heterogeneity in precipitation and moisture transport over China and their connections with anthropogenic emissions and natural variabilityen_US
dc.typeThesisen_US
thesis.degree.departmentFaculty of Engineering and Applied Scienceen_US
thesis.degree.disciplineEngineering - Environmental Systemsen_US
thesis.degree.grantorUniversity of Reginaen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophy (PhD)en_US
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