Relationships between Indian Ocean sea surface temperature and the rainfall of Sri Lanka
Relationships between Indian Ocean sea surface temperature and the rainfall of Sri Lanka
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印度洋海面温度与斯里兰卡降雨量的关系
DOI：
10.2151/jmsj1965.66.1_103
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
R. Suppiah
中科院分区：
文献类型：
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作者：
R. Suppiah
通过使用经验正交函数（EOF）分析来检查印度洋海面温度（SST）的时空变化。第一个 EOF 模式解释了总方差的 20.54%，表明正值揭示了研究区域的一致年际变化。第一EOF模式的时间系数显示与太平洋海温异常有很强的关系。因此，厄尔尼诺/南方涛动（ENSO）事件几乎同时在第一EOF模态的时间系数中观测到。功率谱分析揭示了 18 至 48 个月的主峰，涵盖了准两年一次振荡 (QBO) 和南方涛动现象的主周期（30 至 40 个月）。第二和第三 EOF 模式解释的贡献相对较少，分别占总方差的 5.6% 和 5.1%。考虑所有月份，海表温度异常第一EOF模态的时间系数与斯里兰卡降水第一EOF模态的时间系数之间存在弱正相关系数，但在10月、11月和12月，与ENSO事件的成熟期和衰减期重合的月份，存在较强的相关性。太平洋和印度洋海温距平与上述月份降水距平的正相关关系首先出现在3月和4月，随后逐渐增强到同期的显着水平。在夏季季风季节，阿拉伯海海温存在强烈的季节和区域变化，强烈影响斯里兰卡的降雨，尤其是在该岛的西南象限。本季降雨量与同期阿拉伯海海温呈显着正相关，与前几个月、前六个月呈显着负相关。相关系数符号的变化发生在夏季季风前一年的11月至12月，因此提前几个月预示斯里兰卡降雨量过多和不足可能是有用的。
Spatial and temporal variations of the sea surface temperature (SST) over the Indian Ocean are examined by using empirical orthogonal function (EOF) analysis. The first EOF mode explains 20.54% of the total variance indicating positive values which reveal coherent interannual variations over the study area. Time coefficients of the first EOF mode show a strong relationship with the Pacific SST anomalies. Therefore, the El Nino/Southern Oscillation (ENSO) events are observed in the time coefficients of the first EOF mode almost simultaneously. Power spectrum analysis reveals a dominant peak ranging from 18 to 48 months which covers the quasi-biennial oscillation (QBO) and the dominant cycle in the Southern Oscillation phenomenon (30 to 40 months). The second and third EOF modes explain relatively less contributions, 5.6% and 5.1% of the total variance. A weak positive correlation coefficient is observed between the time coefficients of the first EOF mode of SST anomalies and the time coefficients of the first EOF mode of the rainfall over Sri Lanka when all months are considered, but strong relationships are noticed for the months of October, November and December which coincide with the mature and decay stages of ENSO events. The positive relationships between SST anomalies of the Pacific and Indian Oceans and rainfall anomalies of the above mentioned months first appear in March and April, and then gradually build up towards the significant level in the concurrent months. In the case of the summer monsoon season, Arabian Sea SSTs, where strong seasonal and regional variations are found, strongly influence the rainfall of Sri Lanka, particularly striking in the southwestern quadrant of the island. Rainfall of this season has a significant positive correlation with the SST over the Arabian Sea during the concurrent period, but significant negative correlation with the previous months, before six months. The changes in the sign of the correlation coefficients occur in the months of November-December of the year before the summer monsoon, thus it may be useful to foreshadow the excess and deficit rainfall over Sri Lanka few months in advance.