Investigate Influence of Anthropogenic Temperature Increase on Climate Extremes Through A Dynamical Downscaling Approach - A Chinese Case Study

Date
2018-04
Authors
Zhu, Jinxin
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Publisher
Faculty of Graduate Studies and Research, University of Regina
Abstract

The study presented in this thesis investigated the relationships between climate change and extreme events in China through high-resolution climate projections, and examination of the compound effects of temperature, among multiple climatic variables, at regional scales. The Clausius-Clapeyron (CC) relation was used to investigate the relationship between temperature increases and precipitation extremes. The likely changes in precipitation and precipitation extremes across the country were also evaluated to help in understanding the local climatic response to global warming. The relationship between temperature increases and changes in high-temperature extremes, and simulations of the compound effects of relative humidity and high-temperature extremes, were unraveled using a dynamical downscaling approach. The impact of climate warming on wind strength was also studied, and wind chill effects were projected on low-temperature extremes. After a systematic review of human thermal climate indices, selected indices were adopted to project the compound effects of temperature, relative humidity, wind, and solar radiation to provide a comprehensive assessment of climate change impacts and to quantify climate/health relations over China. The potential changes in intensity and frequency of the compound extremes were assessed over China, in the context of global warming. The impact of global warming on the characteristics of mean and extreme precipitations over China was investigated through a dynamical downscaling approach. As a basis for projecting changes in daily rainfall extremes, it was found that ii rainfall intensity increased, following either the CC, or super CC relation, over a certain atmospheric temperature range (from 0 to 22°C). For temperatures above 22°C, a negative correlation between temperature and precipitation was found, which could be caused by a strong positive feedback from drying soil. A shift in the distribution of precipitation, from light to intense, was detected in all projections for China. Temperatures, relative humidity, and relationship among them were investigated here for a comprehensive assessment of climate change impacts over China. There was a significant change in the temperature and a relatively small change in relative humidity. The compound effects of high-temperatures and relative humidity were substantially smaller than has generally been anticipated for China. Human thermal climate indices were investigated to provide a comprehensive assessment of climate change impacts over China. The physiological impacts of global warming on humans, represented by human perceived equivalent temperature (HPET), under both normal and extreme conditions, have been well studied. The uncertainty that arose from using multiple climate indices and uncertainty from using different emissions scenarios were compared. Results indicated that the range in HPETs that arose from method uncertainty is greater than the range that arose from emissions uncertainty for every sub-region in China

Description
A 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. xix, 238 p.
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