Tropical gradient influences on Caribbean rainfall
Tropical gradient influences on Caribbean rainfall
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热带梯度对加勒比降雨的影响
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Jayaka Campbell
中科院分区：
文献类型：
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作者：
Michael A. P. Taylor;Tannecia S. Stephenson;A. Owino;A. Chen;Jayaka Campbell
[1]作为加勒比气候驱动因素区域系统的一部分，包括大西洋暖池(AWP)和加勒比低空急流(CLLJ)，流域间和流域内梯度发挥着重要作用。当加勒比海在5月至11月期间处于潮湿状态时，加勒比海的近地表地势低于附近的东热带太平洋和东热带大西洋。因此，加勒比地区通过对流层中部垂直上升，与热带东太平洋和热带东大西洋的纬向环流相连。加勒比海也是温暖的，有一个温和的东风流态，表明信风减弱。由于太平洋-加勒比和加勒比-大西洋环流一侧或两侧的变化(并通过其地球位势梯度的变化来诊断)造成的偏离这一状态，合理地跟踪了加勒比地区在季节内和年际时间尺度上从潮湿到干燥的转变，反之亦然。这项研究还利用梯度的变化来洞察为什么在全球变暖的情况下，面对更温暖的地表温度，加勒比地区在传统的雨季预计会更加干燥。加勒比海似乎进入了“七月”模式，这种模式持续了整个北方夏季。该模式的特点是加勒比海(太平洋和大西洋)的高位势(低)位势，较强的CLLJ，以及尽管表面温度较高，但加勒比地区的异常下降。
[1] Interbasin and intrabasin gradients play an important role as a part of a regional system of Caribbean climate drivers, which include the Atlantic warm pool (AWP) and the Caribbean low-level jet (CLLJ). When the Caribbean is conditioned to be wet between May and November, near-surface geopotentials in the Caribbean are lower than in the nearby eastern tropical Pacific and east tropical Atlantic. As a result, there is vertical ascent in the Caribbean through to the middle troposphere which connects to zonal circulations with both the eastern tropical Pacific and the eastern tropical Atlantic. The Caribbean Sea is also warm, and there is a moderate easterly flow regime, indicating a weakening of the trade winds. Deviations from this state caused by changes in one or both sides of the Pacific-Caribbean and Caribbean-Atlantic circulations (and diagnosed by changes in their geopotential gradients) reasonably track the transition of the Caribbean from wet to dry and vice versa on intraseasonal and interannual time scales. The study also uses changes to the gradients to offer insight into why the Caribbean region is projected to be drier during its traditional rainy season in the face of warmer surface temperatures under global warming. The Caribbean seemingly enters into a “July” mode, which persists for the duration of the boreal summer. The mode is characterized by higher (lower) geopotentials in the Caribbean (Pacific and Atlantic), a stronger CLLJ, and anomalous descent in the Caribbean in spite of the warmer surface temperatures.