Ocean–atmosphere conditions related to severe and persistent droughts in the Mexican Altiplano
Ocean–atmosphere conditions related to severe and persistent droughts in the Mexican Altiplano
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与墨西哥高原严重和持续干旱有关的海洋大气条件
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Sara C. Díaz
中科院分区：
文献类型：
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作者：
José P. Vega;L. Brito‐Castillo;L. Farfán;D. Gochis;L. F. Pineda;Sara C. Díaz
探索了与墨西哥高原地区最严重和最持久的干旱相关的海洋和大气模式。使用12个月时间尺度的标准化降水指数，并与其他大气条件的时间序列进行比较，以确定1970年至2012年的主要干旱事件。该时间序列是根据1970年至2000年墨西哥高原气象站观测到的平均夏季降雨系列的最大方差旋转经验正交函数分析的第二模式得出的。结果表明，最长和最持续的事件发生在1998年至2001年，最严重的干旱事件发生在2011年至2012年，当时太平洋年代际涛动处于负位相，大西洋数十年涛动处于正位相，两者都与拉尼娜事件相结合。美国中北部的大型高空反气旋与高原的干旱有关。在这种情况下，干旱与美国中北部的大型反气旋有关，从而导致墨西哥中北部的比湿度出现负异常。在墨西哥内陆发生干旱的同时，研究区附近的墨西哥中部太平洋沿岸也出现了异常降雨。在不同的大气条件下，海岸和内陆之间可能存在相反的异常行为。我们探讨了驱动墨西哥西海岸和高原之间这种拉锯行为的机制。
Ocean and atmospheric patterns associated with the most severe and most persistent droughts in the Mexican Altiplano region are explored. The standardized precipitation index on a time scale of 12 months was used and compared with time series of other atmospheric conditions to identify major dry episodes from 1970 to 2012. The time series were derived from the second mode of a varimax‐rotated empirical orthogonal functional analysis from the mean summer rainfall series observed at weather stations located in the Mexican Altiplano from 1970 through 2000. The results showed that the longest and most persistent episode occurred from 1998 through 2001, while the most severe dry episode occurred in 2011–2012, when the Pacific Decadal Oscillation was in a negative phase and the Atlantic Multidecadal Oscillation in a positive phase, both in combination with a La Niña event. A large upper‐level anticyclone over the north‐central United States is related to droughts in the Altiplano. Under these conditions, the droughts were linked to a large anticyclone positioned over the central‐north of the United States, with consequent negative anomalies of specific humidity over central‐northern Mexico. Concurrent with droughts in the interior of Mexico, are positive rainfall anomalies along the central Pacific coast of Mexico near the study area. Under different atmospheric conditions, opposite anomalous behaviour between the coast and interior can exist. The mechanism driving this see‐saw behaviour between the west coast of Mexico and the Altiplano is explored.