Influences of El Nino-Southern Oscillation (ENSO) and Madden-Julian Oscillation (MJO) on the Stratosphere

厄尔尼诺-南方涛动（ENSO）和马登-朱利安涛动（MJO）对平流层的影响

• 批准号: 0733698
• 负责人: Bryan Weare
• 金额: $ 32.14万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0733698&HistoricalAwards=false
• 关键词: Influences; El; Nino; Southern; Oscillation

The conventional view has been that the lower atmosphere influences the stratosphere primarily through planetary waves that emerge from the troposphere in middle and high latitudes. Recently, however, evidence has emerged that the leading modes of variability of the tropical troposphere, the El Nino-Southern Oscillation (ENSO) and the Madden-Julian Oscillation (MJO), influence the tropical and extratropical stratosphere. Multiple pathways have been proposed for such influences. In this project these pathways will be explored using observational data and the output from troposphere-stratosphere global climate models (GCMs). Observations will comprise the ERA-40 analyses of meteorological fields and ozone from the European Center for Medium Range Weather Forecasting (ECMWF) and satellite observations of outgoing long-wave radiation to characterize convection.Weare and his collaborators will establish indices of the key ENSO and MJO modes. Statistical techniques will be used to determine the dominant patterns of variability in the stratosphere. Using an extension of the singular value decomposition (SVD) method that incorporates multiple variables and data at temporal lags, they will describe the three dimensional relationships between tropical convection, as it is modulated by the MJO and ENSO, and the meteorology of the stratosphere and the distribution of stratospheric ozone. Based on the relationships that appear in these exploratory analyses, they will develop diagnostic tests of specific proposed pathways for tropical influences on the stratosphere.GCM output will be selected from one or more models, based on the quality of the simulations of stratospheric variability and the model representations of ENSO and the MJO. The troposphere-stratosphere coupling in this, or these, GCMs will be analyzed, in order to identify deficiencies in their simulation(s) of this coupling, with the goal of suggesting model improvements that could yield model troposphere-stratosphere coupling that is more consistent with observations.Broader impacts of this project are in validating widely used stratospheric data sets, improving our understanding of the processes that influence trends in stratospheric ozone, and, to the extent that troposphere-stratosphere coupling is an important aspect of climate change, improving projections of future climate. Two graduate students will be trained.

传统观点认为，低层大气主要通过中高纬度对流层产生的行星波影响平流层。 然而，最近出现的证据表明，热带对流层的主要变率模式，厄尔尼诺-南方涛动（ENSO）和马登-朱利安涛动（MJO），影响热带和热带外平流层。 对于这种影响，已经提出了多种途径。在本项目中，将利用观测数据和对流层-平流层全球气候模式的输出来探索这些路径。 观测工作将包括欧洲中期天气预报中心对气象场和臭氧的ERA-40分析，以及为确定对流特征而对向外长波辐射进行的卫星观测，Weare及其合作者将确定关键的ENSO和MJO模式的指数。 将使用统计技术来确定平流层的主要变化模式。使用扩展的奇异值分解（SVD）方法，结合多个变量和数据的时间滞后，他们将描述热带对流之间的三维关系，因为它是由MJO和ENSO调制，平流层的气象和平流层臭氧的分布。 根据这些探索性分析中出现的关系，他们将对热带对平流层影响的具体拟议路径进行诊断测试，将根据平流层变率模拟的质量以及厄尔尼诺/南方涛动和赤道/南方涛动模式的表述，从一个或多个模式中选择全球环流模式的输出。 将分析这一或这些大气环流模式中的对流层-平流层耦合，以查明其对这种耦合的模拟中的不足之处，目的是提出模型改进建议，使对流层-平流层耦合模型与观测更加一致。提高我们对影响平流层臭氧趋势的过程的认识，并在对流层-平流层耦合是气候变化的一个重要方面的情况下，改进对未来气候的预测。将培养两名研究生。