The Cape Town "Day Zero" drought and Hadley cell expansion

被引：79

作者：

Burls, Natalie J. ^{[1
,2
,3
]}

Blamey, Ross C. ^{[3
]}

Cash, Benjamin A. ^{[1
,2
]}

Swenson, Erik T. ^{[1
,2
]}

al Fahad, Abdullah ^{[1
,2
]}

Bopape, Mary-Jane M. ^{[4
]}

Straus, David M. ^{[1
,2
]}

Reason, Chris J. C. ^{[3
]}

机构：

[1] George Mason Univ, Dept Atmospher Ocean & Earth Sci, Fairfax, VA 22030 USA

[2] George Mason Univ, Ctr Ocean Land Atmosphere Studies, Fairfax, VA 22030 USA

[3] Univ Cape Town, Dept Oceanog, Private Bag X3, ZA-7701 Rondebosch, South Africa

[4] South African Weather Serv, Private Bag X097, ZA-0001 Pretoria, South Africa

来源：

NPJ CLIMATE AND ATMOSPHERIC SCIENCE | 2019年 / 2卷 / 1期

基金：

美国国家科学基金会; 美国国家航空航天局; 美国海洋和大气管理局; 英国自然环境研究理事会;

关键词：

SOUTH-AFRICA; RAINFALL; TRENDS; OZONE; VARIABILITY;

D O I：

10.1038/s41612-019-0084-6

中图分类号：

P4 [大气科学（气象学）];

学科分类号：

0706 ; 070601 ;

摘要：

In early 2018, Cape Town (population similar to 3.7 million) was at risk of being one of the first major metropolitan areas in the world to run out of water. This was due to a severe multi-year drought that led to the levels of supply dams falling to an unprecedented low. Here we analyze rainfall data from the city catchment areas, including rare centennial records from the surrounding region, to assess the severity of the 2015-2017 drought. We find that there has been a long-term decline in the number of winter rainfall days, but this trend has been generally masked by fluctuations in rainfall intensity. The recent drought is unprecedented in the centennial record and represents a combination of the long-term decline in rainfall days and a more recent decline in rainfall intensity. Cold fronts during the winter months are responsible for most of the rainfall reaching Cape Town and our analysis shows no robust regional trend in the number of fronts over the last 40 years. Rather, the observed multidecadal decline in rainfall days, which threatens to increase the occurrence of severe drought, appears to be linked to a decrease in the duration of rainfall events associated with cold fronts. This change in rainfall characteristics associated with fronts appears to be linked to Hadley Cell expansion seen across the Southern Hemisphere and an increasing trend in post-frontal high-pressure conditions that suppress orographically enhanced rainfall.

引用

页数：8

共 37 条

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