SGER: Understanding Tropical-Subtropical Forcing and Predictability of Long-Term North American Drought in Coupled Models

SGER：了解耦合模型中的热带-亚热带强迫和北美长期干旱的可预测性

• 批准号: 0739658
• 负责人: Kristopher Karnauskas
• 金额: $ 3万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0739658&HistoricalAwards=false
• 关键词: SGER; Understanding; Tropical; Subtropical; Forcing

This is a grant under a Climate Variability and Predictability (CLIVAR) Program pilot project called DRICOMP, for the Drought in Coupled Models Project, which focuses on making initial explorations into the mechanisms of drought as they are represented in the output of global climate models and on attempting to assess the reliability of these models in simulating drought.A growing body of literature indicates that El Nino - Southern Oscillation (ENSO) is a fundamental driver of global drought variability and that La Nina-like conditions play a key role in the circulation anomalies leading to North American drought. An important yet poorly understood process with strong implications for understanding and predicting long-term North American drought is how the coupled ocean-atmosphere system maintains persistent cool conditions in the equatorial Pacific Ocean.This project will make an initial attempt to answer four questions: (1) how are persistent cool episodes in the equatorial Pacific Ocean represented in state-of-the-art coupled climate models, (2) through what physical mechanisms do such conditions lead to persistent North American drought, (3) how can an understanding of such questions serve to extend the predictive lead time for long-term North American drought, and (4) how do the mechanisms and prospects for predictability depend on the essence of a climate in transition?A two-pronged approach will be taken: first, a selection of coupled models as determined from the details of their ocean component will be used to characterize and explain the representation of persistent cool equatorial Pacific conditions; secondly, long-term North American drought variability (in terms of the Palmer drought severity index - PDSI) and its relationships with the equatorial Pacific, including how that appears to depend on anthropogenic forcing, will be analyzed in the full suite of Climate Model Intercomparison Project 3 (CMIP3) climate models. The problem of predictability at extended lead times will be explored by ascertaining how the remote forcing field itself (i.e., low-frequency evolution of equatorial Pacific SST) is modulated, and the coherence between that signal and the PDSI.Broader impacts of these are in its potential contribution to improved prediction of North American drought at extended leads and in supporting the principal investigator, who is a graduate student.

这是在气候可变性和可预测性（Clivar）计划飞行员项目中的赠款，称为Dricomp，对于耦合模型项目中的干旱项目，该项目的重点是将初步探索介绍为干旱的机制，因为它们是全球气候模型和全球气候模型的输出的代表在试图评估这些模型在模拟干旱中的可靠性时，文献的越来越多表明，埃尔尼诺 - 南方振荡（ENSO）是全球干旱变异性的基本驱动力，并且像拉尼娜（La Nina）一样的条件在循环中起关键作用导致北美干旱的异常。 一个重要但知之甚少的过程，对理解和预测长期北美干旱具有强烈影响的过程是，耦合的海洋 - 大气系统如何在赤道太平洋中保持持续的凉爽条件。该项目将最初尝试回答四个问题：（（ 1）在最先进的耦合气候模型中代表的赤道太平洋中的持续凉爽情节如何通过这种情况导致持续的北美干旱，（3）如何理解对这种情况的持续性。这些问题有助于延长长期北美干旱的预测提前时间，（4）可预测性的机制和前景如何取决于过渡中气候的本质？根据其海洋成分细节确定的耦合模型的选择将用于表征和解释持续的冷赤道太平洋条件的表示。其次，长期的北美干旱变异性（就帕尔默干旱严重程度指数-PDSI而言）及其与赤道太平洋的关系，包括如何在气候模型对室内的完整套件中分析似乎取决于人为强迫的依赖人为强迫项目3（CMIP3）气候模型。 通过确定远程强迫场本身（即赤道太平洋SST的低频演变）如何调制，并且该信号与PDSI之间的相干性在其中。它潜在地贡献了对北美干旱在扩展铅的预测以及支持研究生的主要研究人员的潜在贡献。