对流层和平流层温度中ENSO信号的多种资料比较

摘要

episodes of ENSO are revealed The MSU data are taken as a benchmark to evaluate the veracity of ENSO signals described by different reanalysis datasets. The results show that, in the middle troposphere, the symmetrical components of temperature anomalies associated with ENSO feature a dumbbell-shaped pattern in the eastern Pacific, while the wave structures are evident, stretching from the Pacific to North America, with 3℃ maximum located in the eastern Pacific and northern North America; on the contrary, negative values turn up in the North Pacific, South Asia, and the South Pacific, with the minimum of -3. 2℃ centered in southwestern China. The asymmetrical components are only evident in most of the high latitudes of the Northern Hemisphere. In the lower stratosphere, the symmetrical components of ENSO related temperature anomalies are negative in the eastern Pacific, Greenland, and the North Atlantic, with the minimum -7℃ located in the North Atlantic. The positive values occupies the region north of 30°N during 70°W- 70°E, with the maximum 6℃ centered in northeastern Russia. The asymmetrical components are obvious in the high latitudes of the Northern Hemisphere, and the maximum is 5. 7°C. The reverse signals between the middle troposphere and the lower stratosphere are found in the equatorial eastern Pacific, the South Pacific, the North Pacific, southern China, Greenland, and some areas of the North Atlantic, while northern North America sees the same signals. Further studies indicate that temperatures averaged over 850 - 300 hPa and 100-30 hPa can well represent the ENSO-related signals in the middle troposphere and the lower stratosphere respectively.%本文利用1980～1999年卫星资料Microwave Sounding Unit (MSU)和5种再分析资料(ERA40、JRA25、NCEP1、NCEP2、MERRA),分析了北半球冬季全球对流层中层和平流层低层温度变化中的ENSO信号,讨论了ENSO暖冷位相时温度异常的对称性和非对称性,并以MSU卫星资料为标准,评估了各再分析资料描述ENSO信号的准确性.结果表明,在对流层中层,伴随ENSO暖、冷位相的温度异常的对称分量,在东太平洋呈典型的“亚铃型”变暖信号,太平洋—北美遥相关型显著,暖异常中心位于赤道东太平洋和北美洲北部地区,最大值3℃左右；而北太平洋、南亚、南太平洋为冷异常中心,最大值在中国西南部,可达-3.2℃.其非对称分量在北半球中高纬地区较大,冷暖异常可达±1.5℃.在平流层低层,伴随ENSO暖、冷位相出现的温度异常的对称分量,在东太平洋、格陵兰岛及北大西洋为显著冷异常,最大值出现在北大西洋地区,为-7℃左右；在北半球中高纬30°N以北、70°W～70°E之间的地区为较强暖异常,最大值出现在70°N的俄罗斯东北部,为6℃左右.温度异常只在北半球高纬度地区表现出较强的非对称性,最大值可达5.7℃.对比而言,在东太平洋、南太平洋、北太平洋、中国南部地区、格陵兰岛以及北大西洋部分地区,平流层—对流层ENSO信号温度异常反号；北美洲北部对流层—平流层温度变化同号.不同再分析资料的850～300hPa和100～30hPa的平均温度,均能很好地反映对流层中层和平流层低层的ENSO信号特征.