Study on Snow Depth Anomaly over Eurasia, Indian Rainfall and Circulations
Study on Snow Depth Anomaly over Eurasia, Indian Rainfall and Circulations
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DOI：
10.2151/jmsj.83.237
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发表时间：
2005-04
影响因子：
3.1
通讯作者：
G. Singh;Jai‐Ho Oh
中科院分区：
文献类型：
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作者：
G. Singh;Jai‐Ho Oh
根据1941-1995年苏联历史日积雪深度（HSDSD-II）数据发现，欧亚大陆东部（70 E-160 E，35 N-65 N）冬春季雪深异常与随后的印度夏季季风降雨（ISMR）呈正相关，而欧亚西部（25 E-70 E，35 N-65 N）则呈负相关。在最近的研究期间（1975-1995），这种相关性随着欧亚大陆西部冬季积雪深度异常而变得更强和负相关。根据欧亚大陆西部冬季雪深标准化，选取四年高雪年（1966年、1968年、1979年和1986年）和两年低雪年（1961年和1975年）。上述对比雪年期间雪深的 Pentad（五天平均值）分析表明，高/低雪与迟/早雪消失有关。 NCEP/NCAR重分析数据用于研究高/低雪年季节性季风环流的一些重要大气特征，以及ISMR不足/过多。本研究的重要发现是：（1）冬/春积雪的异常持续性延迟了春季大陆加热，导致印度上空弱热低压和弱季风西风，（2）速度势差场显示印度上空完全相位反转。从高雪年到低雪年的偶极子结构以及(3)温度和相关环流场表明东亚低空急流也受到欧亚雪异常的显着影响。
Based on Historical Soviet Daily Snow Depth (HSDSD-II) data for the period 1941-1995, it is found that winter/spring snow depth anomalies over east Eurasia (70 E-160 E, 35 N-65 N) is positively correlated, while west Eurasia (25 E-70 E, 35 N-65 N) is negatively correlated with subsequent Indian summer monsoon rainfall (ISMR). The correlations become stronger and negative with winter snow depth anomaly over west Eurasia during the recent period of study (1975-1995). Four years of high snow (1966, 1968, 1979 and 1986) and two years of low snow (1961 and 1975) are selected on the basis of standardized winter snow depth anomaly over west Eurasia. The Pentad (Fivedays average) analysis of snow depth during the above contrasting snow years show that high/low snow is associated with late/early snow disappearance. NCEP/NCAR reanalyzed data are used for the study of some important atmospheric characteristics of seasonal monsoon circulation during high/low snow years, followed by deficient/excess ISMR.The important findings ofthis study are: (1) the anomalous persistence of winter/spring snow delays the spring time continental heating, results in weak thermal low and weak monsoon westerlies over India, (2) the difference fields of Velocity Potential shows complete phase reversal in the dipole structure from high to low snow years and (3) the temperature and related circulation fields show that low level jet over east Asia is also considerably influenced by Eurasian snow anomaly.