The Role of the Tropically Excited Arctic Warming Mechanism on the Warm Arctic Cold Continent Surface Air Temperature Trend Pattern
The Role of the Tropically Excited Arctic Warming Mechanism on the Warm Arctic Cold Continent Surface Air Temperature Trend Pattern
复制标题
DOI：
10.1029/2019gl082714
复制
发表时间：
2019-07-28
影响因子：
5.2
通讯作者：
Lee, Sukyoung
中科院分区：
文献类型：
--
作者：
Clark, Joseph P.;Lee, Sukyoung
研究了1979至2017年间所有连续20年的12-2月地表气温(SAT)趋势，从中可以明显看出从冷-北极-暖大陆向暖-北极-冷-大陆趋势模式的转变。这一转变伴随着海平面气压趋势模式的持续转变，这种转变支持北极上空的暖空气平流和大陆上空的冷空气平流。去势的12-2月平均SAT回归到定义为量化热带太平洋海温东西向梯度的去趋势指数，其特征是暖-北极-冷-大陆模式，与近几十年观察到的SAT趋势模式非常相似。热带西太平洋海水的年代际变暖增加了热带太平洋海面温度的东西梯度，从而促成了观察到的温带外SAT趋势的转变。简而言之，在过去的20年里，北极表面温度一直在迅速上升--速度比地球上任何其他地方都快。在北极表面温度迅速上升的同时，北美和欧亚大陆的表面温度却下降了。在北极变暖和大陆变冷的同时，北极和大陆同时变暖。从北极变冷和大陆变暖时期向现在的北极变暖和大陆变冷时期的过渡可能是由于北极上空的南风(自南向北流动)和大陆上的北风(从北向南流动)造成的。这些风把暖空气送进北极，把冷空气送到大陆。我们提出的证据表明，这些环流变化和相关的温度变化，部分是由西热带太平洋水(相对于东热带太平洋)变暖驱动的，大约在上述转变发生的同一时间开始。在以前的研究中讨论了将赤道西部热带太平洋变暖与北极和大陆上的环流变化联系起来的一连串事件。
The December-February surface air temperature (SAT) trend is examined for all consecutive 20-year time periods between 1979 and 2017, from which a transition from a cold-Arctic-warm-continent toward a warm-Arctic-cold-continent trend pattern is evident. This transition is accompanied by a consistent transition in the sea level pressure trend pattern that supports warm air advection over the Arctic and cold air advection over the continents. The regression of the detrended December-February-average SAT onto a detrended index defined to quantify the east-west gradient of tropical Pacific sea surface temperature is characterized by a warm-Arctic-cold-continent pattern much like the SAT trend pattern observed in recent decades. A decadal timescale warming of the western tropical Pacific water has increased the east-west gradient of tropical Pacific sea surface temperature, thus contributing to the observed extratropical SAT trend transition.Plain Language Summary Over the last two decades, Arctic surface temperatures have been increasing rapidly-at a rate faster than anywhere else on the globe. Concurrent with this rapid increase of Arctic surface temperatures, surface temperatures over the North American and Eurasian continents have decreased. This simultaneous warming of the Arctic and cooling of the continents was preceded by a period of simultaneous Arctic cooling and continental warming.The transition from the period of Arctic cooling and continental warming toward the present period of Arctic warming and continental cooling was likely caused by southerly winds (flowing from south to north) over the Arctic and northerly winds (flowing from north to south) over the continents. These winds move warm air into the Arctic and cold air over the continents. We present evidence that these circulation changes, and the associated temperature changes, are driven in part by the warming of the western tropical Pacific water (relative to the eastern tropical Pacific), which started at about the same time that the above transition occurred. The chain of events that link warming of the western equatorial tropical Pacific Ocean to circulation changes over the Arctic and continents is discussed in previous studies.