Statistical Connection between the Madden–Julian Oscillation and Large Daily Precipitation Events in West Africa
Statistical Connection between the Madden–Julian Oscillation and Large Daily Precipitation Events in West Africa
复制标题
马登朱利安振荡与西非大型每日降水事件之间的统计联系
DOI：
10.1175/jcli-d-16-0144.1
复制
发表时间：
2017
影响因子：
4.9
通讯作者：
Hoell, Andrew
中科院分区：
文献类型：
--
作者：
Sossa, Awolou;Liebmann, Brant;Bladé, Ileana;Allured, Dave;Hendon, Harry H.;Peterson, Pete;Hoell, Andrew
这项研究的重点是马登-朱利安振荡（MJO）的影响-由一个著名的多变量指数监测-在1981年至2014年期间在西非的大型日降水事件。考虑两个季节：3月至5月是近赤道雨季（MAM），7月至9月是西非季风的高峰期（JAS），此时热带辐合带（ITCZ）位于最北端。虽然MJO相关的季节性平均降雨量的年际变化很大，这里的重点是MJO对日常时间尺度的影响，因为强度，短期，洪水，降雨事件的频率的变化是更重要的西非农业比季节性降水的变化，特别是在几内亚海岸附近，降水丰富。使用复合材料的基础上阈值的每日降水量，平均降水量的变化和频率的最重的每日事件相关联的MJO的。MJO对平均降雨量的预期调制在MAM期间比在JAS期间强得多;但对最大事件（即，日降雨量（超过第90百分位数）在两个季节是相若的。保守的统计测试的本地和现场的意义表明明确的影响MJO的预期的迹象在某些阶段，但影响的性质取决于当地的季节性降水制度。例如，在JAS，MJO的早期阶段增加了萨赫勒季风区的洪水风险，同时为干旱的南部海岸提供了救济。
This study focuses on the impact of the Madden–Julian oscillation (MJO)—as monitored by a well-known multivariate index—on large daily precipitation events in West Africa for the period 1981–2014. Two seasons are considered: the near-equatorial wet season in March–May (MAM) and the peak of the West African monsoon during July–September (JAS), when the intertropical convergence zone (ITCZ) is at its most northerly position. Although the MJO-related interannual variation of seasonal mean rainfall is large, the focus here is on the impacts of the MJO on daily time scales because variations in the frequency of intense, short-term, flood-causing, rainfall events are more important for West African agriculture than variations in seasonal precipitation, particularly near the Guinean coast, where precipitation is abundant. Using composites based on thresholds of daily precipitation amounts, changes in mean precipitation and frequency of the heaviest daily events associated with the phase of the MJO are investigated. The expected modulation of mean rainfall by the MJO is much stronger during MAM than during JAS; yet the modulation of the largest events (i.e., daily rainfall rates above the 90th percentile) is comparable in both seasons. Conservative statistical tests of local and field significance indicate unambiguous impacts of the MJO of the expected sign during certain phases, but the nature of the impact depends on the local seasonal precipitation regime. For instance, in JAS, the early stages of the MJO increase the risk of flooding in the Sahel monsoon region while providing relief to the dry southern coast.
3月至6月赤道大西洋-西非的季节内变化
影响因子：
4.6
作者：
G. Gu
通讯作者：
G. Gu
Madden-Julian 振荡和北方冬季预报技巧：NCEP CFSv2 重新预报分析
DOI：
--
发表时间：
2015
期刊：
影响因子：
--
作者：
Charles Jones;Abheera Hazra;L. Carvalho
通讯作者：
L. Carvalho
1986 年和 87 年夏季西非的飑线和降雨
DOI：
--
发表时间：
2005
期刊：
影响因子：
--
作者：
A. Gaye;A. Viltard;P. De Felice
通讯作者：
P. De Felice