影响西沙群岛冬季风强度的变化特征

Variation Characteristics of Winter Wind In-tensity on Xisha Islands

摘要: 本文利用1971~2013年西沙永兴岛地面常规观测资料，同时结合气候趋势、Morlet小波分析等多种统计分析方法对西沙群岛地区冬季风强度指数及其与气温的关系进行分析，结果表明：1) 冬季风强度指数(WMI)在1971~2013年主要呈现波动状的下降趋势，其回归系数为−0.395(m∙s⁻¹)/10a，趋势系数为−0.615，通过了99.9%的显著性检验。2) 平均气温和最低气温主要表现为显著的上升趋势，且WMI与平均气温、最低气温的相关系数分别为−0.40和−0.38，有较好的负相关关系。3) WMI在20~22 a较大时间尺度上经历了正–负–正–负的交替，在10~12 a的时间尺度上的周期振荡最为明显，在2~4 a的小尺度上，也有更多WMI偏强和偏弱期的循环交替。4) WMI偏强年份东亚大槽强度比偏弱年份要强，蒙古高压在WMI偏强年份较偏弱年份要强。

Abstract: In this paper, the ground observation data in Xisha Yongxing Island from 1971 to 2013 was used to analyzed, combined with statistical analysis methods of climatic trend and Morlet wavelet, the relationship between the winter monsoon index (WMI) and the temperature was analyzed. The results show that: 1) The WMI mainly showed a volatility downward trend from 1971 to 2013 in Yongxing Island. The regression coefficient was −0.395 (m∙s⁻¹)/10a, and the trend coefficient was −0.615, which had past 99.9% significant test. 2) The average temperature and the minimum temperature showed significant upward trends, and the correlation coefficients between WMI and average temperature and minimum temperature were −0.40 and −0.38, respectively, which shows a good negative correlation. 3) WMI undergoes a positive-negative-positive-negative alternation on a large time scale of 20 - 22 a, and the periodic oscillation on the time scale of 10 - 12 a is most obvious. In a small scale of 2 - 4 a, there also existed more cycles of alternating WMI and weaker periods. 4) In the strong WMI year, East Asian trough is stronger than in the weak year, and the Mongolian high pressure is stronger than in the weak WMI year.