在大部分非熱帶海洋中，季節(jié)循環(huán)由太陽輻射的季節(jié)變化支配,。但在熱帶,，海洋表面溫度存在一個強季節(jié)循環(huán)，盡管輻射輸入相對來說保持不變,。James Moum及其同事發(fā)表了多年份觀測結果,，它們表明：來自下面的湍流混合占140° W處赤道太平洋“冷舌”中海平面溫度的季節(jié)循環(huán)幅度的大部分。這些發(fā)現(xiàn)應能提高我們對“厄爾尼諾/南方濤動”循環(huán)的認識,，幫助提高很多海洋-大氣耦合氣候模型的準確性。（生物谷 Bioon.com）
生物谷推薦的英文摘要
Nature doi:10.1038/nature12363
Seasonal sea surface cooling in the equatorial Pacific cold tongue controlled by ocean mixing
James N. Moum, Alexander Perlin, Jonathan D. Nash & Michael J. McPhaden
Sea surface temperature (SST) is a critical control on the atmosphere1, and numerical models of atmosphere–ocean circulation emphasize its accurate prediction. Yet many models demonstrate large, systematic biases in simulated SST in the equatorial ‘cold tongues’ (expansive regions of net heat uptake from the atmosphere) of the Atlantic2 and Pacific3 oceans, particularly with regard to a central but little-understood feature of tropical oceans: a strong seasonal cycle. The biases may be related to the inability of models to constrain turbulent mixing realistically4, given that turbulent mixing, combined with seasonal variations in atmospheric heating, determines SST. In temperate oceans, the seasonal SST cycle is clearly related to varying solar heating5; in the tropics, however, SSTs vary seasonally in the absence of similar variations in solar inputs6. Turbulent mixing has long been a likely explanation, but firm, long-term observational evidence has been absent. Here we show the existence of a distinctive seasonal cycle of subsurface cooling via mixing in the equatorial Pacific cold tongue, using multi-year measurements of turbulence in the ocean. In boreal spring, SST rises by 2 kelvin when heating of the upper ocean by the atmosphere exceeds cooling by mixing from below. In boreal summer, SST decreases because cooling from below exceeds heating from above. When the effects of lateral advection are considered, the magnitude of summer cooling via mixing (4 kelvin per month) is equivalent to that required to counter the heating terms. These results provide quantitative assessment of how mixing varies on timescales longer than a few weeks, clearly showing its controlling influence on seasonal cooling of SST in a critical oceanic regime.
