基于延时相关性的我国降水对ENSO事件响应分析

发布时间：2018-08-11 14:38

【摘要】：恩索（ENSO）是厄尔尼诺(El Nino)和南方涛动(Southern Oscillation)的总称，它是海气相互作用的最强信号，对气候变化的观测和研究有着不可替代的作用。ENSO循环对全球气候变化有着重要影响，ENSO循环的异常会引起洪水、干旱、台风带来的极端天气现象发生，给人民的生命和财产安全带来威胁。我国位于太平洋西海岸的东亚地区，气候变化受ENSO循环影响显著，我国气候变化对太平洋地区的海陆循环异常的响应明显，研究ENSO事件发生对我国气候变化的影响有着重要意义。本文首先以1961年1月到2011年12月期间，我国范围内（72°E-136°E，18°N-54°N）9216（72×128）组格点的地面降水月平均数据为研究对象，通过M-K检验、小波变换分析等方法对其时间序列进行分析，分析结果显示：我国降水以70年代中期为界呈现先减少后稳定伴随小幅度增加的趋势，70年代中期为我国降水量最少点；我国降水1961年-2011年间的2-3年尺度周期性明显，1995年之前30年尺度大周期存在但却不显著。EOF分析结果显示，我国降水量变化呈现由西北到西南递增，变化趋势统一，地域分布明显。分别选择通过海面气压差、海表温度差、综合变量指数定义的ENSO指数， SOI、Nino3.4和Nino4、MEI为研究对象，分析其时间序列，结果显示：变化趋势检验方面，SOI为持续减少，Nino3.4为先减少后稳定，Nino4为先减少后小幅度增加，MEI为先小幅度减少后小幅度增加的趋势；周期分析发现，SOI周期主要为2年，Nino3.4周期主要为2-4年，Nino4周期主要为5年，MEI周期主要为3或5年，ENSO各指数在1-6年尺度的周期都具有显著性，且Nino3.4及Nino4长周期不明显。将四种ENSO指数分别与我国9216组格点月降水序列进行0-12个月尺度的延时相关分析，并记录相关系数最大值，填回格点并绘图。结果显示，与我国降水序列相关系数由大到小的ENSO指数分别为Nino3.4、Nino4、MEI、SOI，其中Nino3.4和Nino4所有格点都通过了0.05水平的显著性检验。经过上述时间序列分析，并结合前人研究成果，选择Nino3.4为ENSO代表指数，记录延时相关性最大时延时月数并作图。结果显示，我国降水相对于Nino3.4响应最大相应延时时间分布大致可以分为西南、中部和我国大部分地区三个区域。按照海洋尼诺指数将ENSO事件发生时海温强度分为极弱、弱、中等、强、极强共5个等级，选择1961年1月到2011年12月期间强度为中等强度以上冷、暖事件为研究对象，分析我国降水量在ENSO事件发生延迟响应月份后的增减情况。在ENSO暖事件发生期间，我国降水变化主要表现为以秦岭-淮河为界，在北方地区降水量多为少于常年同期降水量或降水变化量稳定，南方地区降水量多为多于常年同期降水量。降水量变化以强度影响为主，其次为爆发时间，事件持续时间对降水变化量影响不明显。冷事件发生期间，我国北方地区降水受影响为减少或稳定为主，南方地区降水变化不统一。事件持续时间对于事件对我国降水量变化并不明显，，事件爆发时间对于我国降水变化影响较大。降水变化幅度分析结果显示，西北地区降水变化幅度受ENSO事件影响最大，其次分别为东北地区、华北地区、华中地区和华东地区，东南地区和西南地区受ENSO事件影响较小。
[Abstract]:ENSO is the general name of El Nino and Southern Oscillation. It is the strongest signal of air-sea interaction and plays an irreplaceable role in the observation and study of climate change. Weather phenomena threaten people's lives and property security. China is located in East Asia on the western coast of the Pacific Ocean. Climate change is significantly affected by the ENSO cycle. China's climate change has obvious response to the abnormal sea-land cycle in the Pacific. It is of great significance to study the impact of ENSO events on climate change in China.
In this paper, the monthly mean precipitation data of 9216 (72 *128) grids in China from January 1961 to December 2011 are analyzed by M-K test and wavelet transform. The results show that the precipitation in China decreases first in the mid-1970s. The precipitation in China was the lowest in the mid-1970s. The 2-3-year scale periodicity of precipitation in 1961-2011 was obvious, but the 30-year scale periodicity before 1995 was not significant. The results of EOF analysis showed that the precipitation in China increased from northwest to southwest, and the change trend was unified. The domain distribution is obvious.
The ENSO index, SOI, Nino 3.4 and Nino 4, MEI defined by sea surface pressure difference, sea surface temperature difference and comprehensive variable index were selected as the research objects. The time series analysis showed that the SOI decreased continuously, the Nino 3.4 decreased first and then stabilized, the Nino 4 decreased first and then increased slightly, and the MEI decreased slightly at first. The cycle analysis showed that the SOI cycle was mainly 2 years, the Nino 3.4 cycle was mainly 2-4 years, the Nino 4 cycle was mainly 5 years, the MEI cycle was mainly 3 or 5 years, and the ENSO indices were significant in the 1-6 year scale, and the long periods of Nino 3.4 and Nino 4 were not obvious.
The four ENSO indices were analyzed with the monthly precipitation series of 9216 grid points in China, and the maximum correlation coefficients were recorded. The results showed that the ENSO indices from large to small were Nino 3.4, Nino 4, MEI and SOI, of which Nino 3.4 and Nino 4 were all grid points. Based on the above time series analysis and previous research results, Nino 3.4 is selected as ENSO representative index to record and plot the maximum delay months. The results show that the corresponding delay time distributions with the largest response to Nino 3.4 can be roughly divided into southwest, central and China. Most of the three regions.
According to the ocean Nino index, the SST intensity at the time of ENSO event is divided into five grades: extremely weak, weak, moderate, strong and extremely strong. The cold and warm events with moderate intensity from January 1961 to December 2011 are selected as the research objects to analyze the increase and decrease of precipitation in China after the delayed response month of ENSO event. During the period, the precipitation change in China is mainly manifested as the boundary between Qinling and Huaihe River, the precipitation in the north is less than that in the same period of the year or the precipitation change is stable, and the precipitation in the south is more than that in the same period of the year. During the cold event, the precipitation in the north of China was mainly affected by decreasing or stabilizing, and the precipitation in the South was not uniform. The ENSO event has the greatest influence on the precipitation, followed by the northeast, North China, central and Eastern China, southeast and southwest China.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P732

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