Upscale Feedback of Tropical Atmospheric Synoptic-Scale Variabilities to Intraseasonal Oscillations

热带大气天气尺度变化对季节内振荡的高级反馈

• 批准号: 1106536
• 负责人: Tim Li
• 金额: $ 37万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1106536&HistoricalAwards=false
• 关键词: Upscale; Feedback; Tropical; Atmospheric; Synoptic

The Madden-Julian Oscillation (MJO) is the most significant tropical variability between day-to-day weather and El Niño/La Niña-Southern Oscillation (ENSO). Recent theoretical and modeling studies suggested that the upscale feedback of synoptic-scale (3-10-day) variability (SSV) to MJO is important but our current knowledge in understanding this upscale feedback is very limited. This project articulates an endeavor to investigate the upscale feedback of the tropical SSV to MJO. Specific scientific questions to be addressed are: Through what internal atmospheric and ocean nonlinear processes and surface flux processes does the SSV feed back to the MJO? How do the barotropic/baroclinic energy conversions depend on the MJO phases? What are the phase relationships between MJO convection and nonlinearly rectified surface heat fluxes/apparent heat sources/eddy momentum transport? These questions will be addressed through the analysis of new-generation reanalysis products such as National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), Earth System Research Laboratory (ESRL) 100-year Historical Reanalysis, National Aeronautics and Space Administration (NASA) Modern Era Retrospective-analysis for Research and Applications (MERRA), and European Centre for Medium-Range Weather Forecasts (ECMWF) high-resolution YOTC (Year of Tropical Convection) datasets and through numerical modeling experiments. This project consists of the following three major research components. Firstly, a newly developed eddy kinetic energy (EKE) budget diagnostics will be applied to investigate the role of synoptic eddy interactions with the slowly varying background mean state and the MJO flow in affecting barotropic and baroclinic energy conversions at various phases of MJO. Secondly, the investigator will examine the characteristics of nonlinearly rectified intraseasonal surface latent heat flux (LHF) and its temporal and spatial phase relationships with MJO convection. Thirdly, the investigator will examine to what extend SSV modulates intraseasonal apparent heat and moisture sources and how the nonlinear eddy momentum transport (including the effect of 2-day waves and mesoscale convective systems) exerts an upscale feedback to MJO. The ocean "reddening" process through which high-frequency atmospheric variability affects the intraseasonal SST will be also investigated through a series of ocean general circulation model experiments. The following two nonlinear rectification processes, the nonlinear rectification of the surface wind stress/heat flux and the ocean nonlinear advection process, will be particularly examined.Broader impacts of the research include the contribution to improved representation of the structure and variability of tropical convection from synoptic to intraseasonal timescales in the current state-of-art global climate/weather models, which may further lead to improved skills of extended-range weather and climate forecasts both in the tropics and extratropics, facilitating the forecast potential at the sub-seasonal scale.

马登-朱利安涛动 (MJO) 是日常天气与厄尔尼诺/拉尼娜-南方涛动 (ENSO) 之间最显着的热带变化。最近的理论和模型研究表明，天气尺度的高级反馈 (3)。 -10 天）变异性（SSV）对 MJO 很重要，但我们目前对这种高级反馈的了解非常有限，该项目阐明了研究热带 SSV 对 MJO 的高级反馈的努力。 MJO。需要解决的具体科学问题是：SSV 通过什么内部大气和海洋非线性过程和表面通量过程反馈到 MJO？正压/斜压能量转换如何取决于 MJO 相位？ MJO 对流与非线性整流表面热通量/视热源/涡动量传输之间的关系？这些问题将通过国家环境预测中心等新一代再分析产品的分析来解决。 (NCEP) 气候预报系统再分析 (CFSR)、地球系统研究实验室 (ESRL) 100 年历史再分析、美国国家航空航天局 (NASA) 现代时代研究和应用回顾分析 (MERRA) 以及欧洲媒介中心-范围天气预报（ECMWF）高分辨率YOTC（热带对流年）数据集和数值模拟实验该项目由以下三个主要研究部分组成。首先，新开发的涡动能 (EKE) 预算诊断将用于研究天气涡流与缓慢变化的背景平均状态和 MJO 流的相互作用在影响 MJO 各个阶段的正压和斜压能量转换中的作用。研究人员将研究非线性校正季节内表面潜热通量（LHF）的特征及其与 MJO 对流的时间和空间相位关系。 SSV 的范围如何调节季节内的视热和湿气源，以及非线性涡动量传输（包括 2 天波和中尺度对流系统的影响）如何对 MJO 施加高级反馈 高频大气通过海洋“红化”过程。还将通过一系列海洋大气环流模型实验来研究变化对季节内海温的影响。以下两个非线性校正过程，表面风应力/热通量和海洋的非线性校正。该研究的更广泛影响包括改善当前最先进的全球气候/天气模型中从天气到季节内时间尺度的热带对流结构和变化的表示，这可能会进一步提高热带和温带地区长期天气和气候预报的技能，促进次季节尺度的预报潜力。