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基于MTM-SVD方法的攀西秋雨变化规律分析
王春学1,2, 马振峰2, 毛家勋3
1.四川省气候中心, 四川 成都 610072;2.高原与盆地暴雨旱涝灾害四川省重点实验室, 四川 成都 610072;3.四川省攀枝花市气象局, 四川 攀枝花 617000
摘要:
[目的]研究四川省攀枝花市和凉山州(以下简称攀西地区)秋雨时空变化规律,为攀西秋雨气候预测和防灾减灾提供科学依据。[方法]利用1961—2017年攀西地区18个气象站逐日降水量资料,采用MTM-SVD等方法分析攀西秋雨的时空变化规律。[结果]①攀西秋雨EOF展开第一模态为全区一致变化型,方差贡献率达46.1%,为攀西秋雨主模态,滑动t检验显示攀西秋雨主模态在1995年前后出现过一次显著突变。②1961—2017年攀西秋雨有显著的3.2 a周期,滑动窗口分析显示1995年之前攀西秋雨的准3 a周期非常明显,之后突然消失,转变为显著的准2 a周期。③以1995年为节点分段研究,1961—1994年攀西秋雨3.4 a周期达到了99%的置信度水平,3.0 a周期达到了95%的置信度水平。攀西秋雨准3 a周期典型循环重建表明,第1 a攀西地区整体都为正异常,第2 a正异常强度迅速减弱,大部分转变为负异常,第3 a攀西大部的负异常强度有所增加,即1995年之前攀西秋雨主要表现为“偏强—偏弱—偏弱”的年际变化过程。④1995—2017年攀西秋雨2 a周期达到了99%的置信度水平。准2 a周期典型循环重建表明,第1 a攀西秋雨为全区一致的正异常,第2 a异常情况与第1 a完全相反,即1995年之后攀西秋雨主要表现为强弱交替的异常演变。[结论]攀西秋雨在1995年前后出现气候突变,1961—1994年主要表现为准3 a周期振荡,1995—2017年则以准2 a周期为主。
关键词:  攀西  秋雨  MTM-SVD
DOI:10.13961/j.cnki.stbctb.2018.04.028
分类号:
基金项目:国家自然科学基金项目“华西秋雨年际变化规律及其形成机理研究”(41275097);攀枝花市科技项目(2014CY-N-14)
Spatio-temporal Variation Feature of Autumn Rain in Panxi Region Based on MTM-SVD Method
WANG Chunxue1,2, MA Zhenfeng2, MAO Jiaxun3
1.Sichuan Provincial Climate Center, Chengdu, Sichuan 610072, China;2.Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province, Chengdu, Sichuan 610072, China;3.Panzhihua Meteorological Office of Sichuan Province, Panzhihua, Sichuan 617000, China
Abstract:
[Objective] Studying the spatial and temporal variations of autumn rain in Panxi region(Panzhihua City and Liangshan Prefecture) during 1961-2017, to provide bases for autumn rain prediction and preparedness against consequent disaster.[Methods] Based on the daily precipitation data from 18 meteorology stations in Panxi region during 1961-2017 and the multi taper method-singular value decomposition(MTM-SVD), the spatial and temporal variations of the autumn rain were analyzed.[Results] ① The first mode of EOF expansion in the autumn rain was accordant all over the area and the contribution rate of variance was 46.1%, which is the main mode of the autumn rain. The sliding t test showed that the main mode of the autumn rain had a significant sharp change around 1995. ② MTM-SVD analysis showed that the autumn rain had a significant 3.2 year period in 1961-2017. The slip window analysis showed that before 1995, the quasi 3 year cycle of the autumn rain was very obvious, and the latter period suddenly disappeared, which turned into a significant quasi 2 year cycle. ③ The 3.4 year cycle of autumn rain in 1961-1994 reached a level of 99% confidence, and the 3 year cycle reached a level of 95% confidence. The typical cycle reconstruction of the quasi 3 year showed that before 1995, the autumn rain was mainly characterized by the inter-annual change of "more-less-less". ④ The 2 year cycle of autumn rain in 1995-2017 years reached a level of 99% confidence. The typical cycle reconstruction of the quasi 2 year showed that after 1995, the autumn rain main manifested an abnormal evolution of the alternation of strong and weak.[Conclusion] The autumn rain in Panxi region had an abrupt climate change before and after 1995. It was mainly quasi 3 year periodic oscillation before 1995, and then was replaced by quasi 2 year cycle.
Key words:  Panxi region  autumn rain  MTM-SVD