Trends in Persistent Seasonal-Scale Atmospheric Circulation Patterns Responsible for Seasonal Precipitation Totals and Occurrences of Precipitation Extremes over Canada-Reference-Cited by-同舟云学术

Trends in Persistent Seasonal-Scale Atmospheric Circulation Patterns Responsible for Seasonal Precipitation Totals and Occurrences of Precipitation Extremes over Canada

Published:2019-09-24 Issue:21 Volume:32 Page:7105-7126
ISSN:0894-8755
Container-title:Journal of Climate
language:en
Short-container-title:

Author:

Tan Xuezhi¹^ORCID,Gan Thian Yew²,Chen Shu³,Horton Daniel E.⁴,Chen Xiaohong⁵,Liu Bingjun⁵,Lin Kairong⁵

Affiliation:

1. Department of Water Resources and Environment, School of Civil Engineering, Sun Yat-sen University, Guangzhou, China, and Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada, and Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China, and Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong High Education Institute, Sun Yat-sen University, Guangzhou, China

2. Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada

3. Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada, and State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, China

4. Department of Earth and Planetary Sciences, Northwestern University, Evanston, Illinois

5. Department of Water Resources and Environment, School of Civil Engineering, and Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China, and Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong High Education Institute, Sun Yat-sen University, Guangzhou, China

Abstract

Abstract Both large-scale atmospheric circulation and moisture content in the atmosphere govern regional precipitation. We partition recent changes in mean, heavy, and extreme precipitation for all seasons over Canada to changes in synoptic circulation patterns (dynamic changes) and in atmospheric moisture conditions (thermodynamic changes) using 500-hPa geopotential height and precipitation data over 1979–2014. Using the self-organizing map (SOM) cluster analysis, we identify statistically significant trends in occurrences of certain synoptic circulation patterns over the Canadian landmass, which have dynamically contributed to observed changes in precipitation totals and occurrence of heavy and extreme precipitation events over Canada. Occurrences of circulation patterns such as westerlies and ridges over western North America and the North Pacific have considerably affected regional precipitation over Canada. Precipitation intensity and occurrences of precipitation extremes associated with each SOM circulation pattern also showed statistically significant trends resulting from thermodynamic changes in the atmospheric moisture supply for precipitation events. A partition analysis based on the thermodynamic–dynamic partition method indicates that most (~90%) changes in mean and extreme precipitation over Canada resulted from changes in precipitation regimes occurring under each synoptic circulation pattern (thermodynamic changes). Other regional precipitation changes resulted from changes in occurrences of synoptic circulation patterns (dynamic changes). Because of the high spatial variability of precipitation response to changes in thermodynamic and dynamic conditions, dynamic contributions could offset thermodynamic contributions to precipitation changes over some regions if thermodynamic and dynamic contributions are in opposition to each other (negative or positive), which would result in minimal changes in precipitation intensity and occurrences of heavy and extreme precipitation events.

Funder

National Natural Science Foundation of China

National Key Research and Development Program of China

Publisher

American Meteorological Society

Subject

Atmospheric Science

Link

http://journals.ametsoc.org/jcli/article-pdf/32/21/7105/4858522/jcli-d-18-0408_1.pdf

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