Mega-ENSO与传统ENSO在不同阶段（发展期、衰减期）的气候效应比较研究

发布时间：2018-03-08 04:17

  本文选题：印度夏季降水　切入点：东亚夏季降水　出处：《南京信息工程大学》2016年硕士论文　论文类型：学位论文

【摘要】：厄尔尼诺-南方涛动(ENSO)作为全球最重要的海气耦合现象,已被证实为可预报性来源之一,且对全球天气气候有深远的影响。Mega-ENSO于2013年由Wang等首次提出,是海表温度变率的主模态,具有多年代际时间尺度,从年际到年代际。Mega-ENSO的定义区域包含了热带太平洋以及太平洋的副热带区域。鉴于其有比传统ENSO更为广泛的时空尺度。Mega-ENSO指数可能比传统ENSO包含了更丰富和复杂的气候信息。例如,mega-ENSO是包含了印度夏季降水(ISR)、东亚夏季风降水(EASR)在内的北半球夏季风降水的主要驱动力,而这一作用并未在传统ENSO中得到体现。季风对农业生产、水利用率和食品安全至关重要,其年际变率很大程度上影响农业生产,分布可以对粮食产量造成严重影响,反过来,对人口急剧增长的印度的食品安全产生威胁。因此,掌握季风的新的预报因子、提高其预报技巧至关重要且必要。此外,ENSO和季风是气候系统中相互作用的两个分量。由于ENSO的锁相特征,夏季风通常在其发展期或衰减期。然而,多数研究主要集中在传统ENSO,且极少数关注其发展阶段。运用mega-ENSO指数的目的是获取更多ENSO系统的完整信息。鉴于mega-ENSO是比传统ENSO更加大范围的变率,探究ISR及大气环流是否响应于mega-ENSO及传统ENSO以及它们的不同联系将会非常重要。这是本研究的出发点之一。本文主要比较了典型mega-ENSO-ISR和非典型ENSO-ISR的不同联系。在典型El Nino发展期夏季,印度半岛东北部降水负异常,而在典型La Nina发展期夏季,降水异常型几乎线性相反；对于非典型ENSO,这一“线性相反”的现象消失。此外,在中纬度地区有一纬向异常波列,在典型mega-ENSO发展期夏季其局地响应为欧亚大陆中东部的三极子环流型,这可能是相应的印度次大陆降水异常的原因。相反的,这些特征在非典型ENSO的发展期夏季并不明显。利用CMIP5 9个模式的106年历史运行结果(1900-2005),HadGEM2-ES表现了较好的对于异常环流型的模拟能力,而CanESM2较差。此外,我们还比较了典型mega-ENSO-EASR和非典型ENSO-EASR的在衰减期的不同联系。在典型El Nino衰减期夏季,东亚地区降水三极子异常,而在典型La Nifla衰减期夏季,降水异常型线性相反；对于非典型ENSO,这一现象消失。此外,中纬度地区有一纬向异常波列在典型mega-ENSO衰减期夏季其局地响应为欧亚大陆中东部的三极子环流型。相反的,在非典型ENSO的衰减期夏季主要的环流型出现在北太平洋。同样利用CMIP5 9个模式结果,HadCM3表现了较好模拟能力,而CanESM2较差。此外,模式对于典型mega-ENSO-ISR、 ENSO-EASR联系的模拟能力的差别还有可能源于其对典型mega-ENSO特征的模拟能力。
[Abstract]:El Nino Southern Oscillation (ENSO), as one of the most important coupled sea and air phenomena in the world, has been proved to be one of the most predictable sources, and has far-reaching influence on the global weather and climate. Mega-ENSO was first proposed by Wang et al in 2013, which is the main mode of sea surface temperature variability. With years of intergenerational time scales, The definition region of interannual to Interdecadal .Mega-ENSO includes the tropical Pacific and subtropical regions of the Pacific Ocean. Given that it has a broader space-time scale than traditional ENSO, the Mega-ENSO index may contain a richer and more complex gas than traditional ENSO. For example, mega ENSO is the main driving force of summer monsoon precipitation in the Northern Hemisphere, including the Indian summer precipitation ISRN, the East Asian summer monsoon precipitation EASR, etc. But this role is not reflected in traditional ENSO. Monsoon is very important to agricultural production, water utilization rate and food safety. Its interannual variability affects agricultural production to a large extent, distribution can have a serious impact on grain production, in turn, A threat to food security in India, with a rapidly growing population. In addition, ENSO and monsoon are two components of interaction in the climate system. Due to the phase-locked characteristics of ENSO, summer monsoon is usually in its development or attenuation period. Most of the studies focus on traditional ENSO, and very few focus on its stage of development. The purpose of using mega-ENSO index is to obtain more complete information about ENSO system. Since mega-ENSO is a rate of variability with a larger range than traditional ENSO, It will be important to explore whether ISR and atmospheric circulation respond to mega-ENSO and traditional ENSO and their different connections. This is one of the starting points of this study. This paper mainly compares the different relationships between typical mega-ENSO-ISR and atypical ENSO-ISR. El Nino development period in summer, In the typical La Nina development summer, the anomalous pattern of precipitation is almost linearly opposite. For the atypical ENSO, this "linear opposite" phenomenon disappears. In addition, there is a zonal anomalous wave train in the mid-latitude region. In the summer of a typical mega-ENSO development period, the local response is the tripole circulation pattern in the east-central Eurasia, which may be the cause of the corresponding precipitation anomaly in the Indian subcontinent. These characteristics are not obvious in the development period of atypical ENSO in summer. Using the 106-year operating results of CMIP5 9 models, HadGEM2-ES shows a good ability to simulate anomalous circulation patterns, but CanESM2 is poor. We also compare the relationship between typical mega-ENSO-EASR and atypical ENSO-EASR in the attenuation period. In the typical El Nino attenuation period, the precipitation tripole anomaly in East Asia is different from that in the typical La Nifla attenuation period. For atypical ENSO, this phenomenon disappears. In addition, in the summer of a typical mega-ENSO attenuation period, the local response of a zonal anomalous wave train in the mid-latitude region is a tripole circulation pattern in the east-central Eurasian continent. The main circulation patterns in summer during the attenuation period of atypical ENSO occur in the North Pacific Ocean. The results of CMIP5 9 models also show good simulation ability, but CanESM2 is poor, in addition, the main circulation patterns occur in the North Pacific Ocean during the attenuation period of atypical ENSO. For typical mega-ENSO-ISR, the difference in simulation ability of ENSO-EASR linkages may also be due to its ability to simulate typical mega-ENSO features.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P732
，

本文编号：1582370