High Latitude Modulation of the Holocene North American Monsoon
High Latitude Modulation of the Holocene North American Monsoon
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DOI：
10.1029/2022gl099772
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发表时间：
2022-08
影响因子：
5.2
通讯作者：
C. Routson;M. Erb;N. McKay
中科院分区：
文献类型：
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作者：
C. Routson;M. Erb;N. McKay
北美季风（NAM）是墨西哥大部分地区和美国西南部的重要降雨来源。西风可以抑制季风环流，影响季风的时间、强度和范围。最近的北极变暖正在减少赤道和极地之间的温度梯度，这可能会削弱西风带;然而，这些变化对NAM的影响是不确定的。在这里，我们提出了一个新的综合指数的全新世NAM。我们发现季风强度在大约7,000年前达到最大值，此后一直在减弱。代理观测的温度，水文气候和上升流，沿着与模式模拟，表明NAM调制的西风带在全新世。如果观测到的全新世模式适用于当前的变暖，那么较弱的纬向温度梯度和较弱的西风带可能导致未来更强的NAM。
The North American monsoon (NAM) is an important source of rainfall to much of Mexico and southwestern United States. Westerly winds (westerlies) can suppress monsoon circulation and impact monsoon timing, intensity, and extent. Recent Arctic warming is reducing the temperature gradient between the equator and the pole, which could weaken the westerlies; however, the implications of these changes on the NAM are uncertain. Here we present a new composite index of the Holocene NAM. We find monsoon strength reached a maximum circa 7,000 years ago and has weakened since then. Proxy observations of temperature, hydroclimate and upwelling, along with model simulations, show that the NAM was modulated by the westerlies over the Holocene. If the observed Holocene pattern holds for current warming, a weaker meridional temperature gradient and weaker westerlies could lead to a stronger future NAM.