Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.1175/JCLI-D-16-0696.1 |
Weakening and Shifting of the Saharan Shallow Meridional Circulation during Wet Years of the West African Monsoon | |
Shekhar, Ravi; Boos, William R. | |
2017-09-01 | |
发表期刊 | JOURNAL OF CLIMATE |
ISSN | 0894-8755 |
EISSN | 1520-0442 |
出版年 | 2017 |
卷号 | 30期号:18 |
文章类型 | Article |
语种 | 英语 |
国家 | USA |
英文摘要 | The correlation between increased Sahel rainfall and reduced Saharan surface pressure is well established in observations and global climate models and has been used to imply that increased Sahel rainfall is caused by a stronger shallow meridional circulation (SMC) over the Sahara. This study uses two atmospheric reanalyses to examine interannual variability of Sahel rainfall and the Saharan SMC, which consists of northward near-surface flow across the Sahel into the Sahara and southward flow near 700 hPa out of the Sahara. During wet Sahel years, the Saharan SMC shifts poleward, producing a drop in low-level geopotential and surface pressure over the Sahara. Statistically removing the effect of the poleward shift from the low-level geopotential eliminates significant correlations between this geopotential and Sahel precipitation. As the Saharan SMC shifts poleward, its midtropospheric divergent outflow decreases, indicating a weakening of its overturning mass flux. The poleward shift and weakening of the Saharan SMC during wet Sahel years is reproduced in an idealized model of West Africa; a wide range of imposed sea surface temperature and land surface albedo perturbations in this model produce a much larger range of SMC variations that nevertheless have similar quantitative associations with Sahel rainfall, as in the reanalyses. These results disprove the idea that enhanced Sahel rainfall is caused by strengthening of the Saharan SMC. Instead, these results are consistent with the hypothesis that a stronger SMC inhibits Sahel rainfall, perhaps by advecting midtropospheric warm and dry air into the precipitation maximum. |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000408613400017 |
WOS关键词 | IDEALIZED 2-DIMENSIONAL FRAMEWORK ; INTERTROPICAL CONVERGENCE ZONE ; SAHEL RAINFALL VARIABILITY ; HEAT LOW ; SEASONAL EVOLUTION ; MOIST CONVECTION ; WATER-VAPOR ; DYNAMICS ; PRECIPITATION ; DROUGHT |
WOS类目 | Meteorology & Atmospheric Sciences |
WOS研究方向 | Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/20932 |
专题 | 气候变化 |
作者单位 | Yale Univ, New Haven, CT 06520 USA |
推荐引用方式 GB/T 7714 | Shekhar, Ravi,Boos, William R.. Weakening and Shifting of the Saharan Shallow Meridional Circulation during Wet Years of the West African Monsoon[J]. JOURNAL OF CLIMATE,2017,30(18). |
APA | Shekhar, Ravi,&Boos, William R..(2017).Weakening and Shifting of the Saharan Shallow Meridional Circulation during Wet Years of the West African Monsoon.JOURNAL OF CLIMATE,30(18). |
MLA | Shekhar, Ravi,et al."Weakening and Shifting of the Saharan Shallow Meridional Circulation during Wet Years of the West African Monsoon".JOURNAL OF CLIMATE 30.18(2017). |
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