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.

Madden-Julian振荡（MJO）是日常天气和ElNiño/LaNiña-Southern振荡（ENSO）之间最重要的热带变化。最近的理论和建模研究表明，对MJO的概要级（3-10天）可变性（SSV）的高档反馈很重要，但是我们当前了解这种高档反馈的知识非常有限。该项目阐明了一项努力，以调查热带SSV向MJO的高档反馈。要解决的具体科学问题是：通过哪些内部大气和海洋非线性过程和表面通量过程，SSV会反馈到MJO？正压/斜视能转化如何取决于MJO相？ MJO会议与非线性整流的表面热通量/明显的热源/涡流动量传输之间的相位关系是什么？ 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）高分辨率YOTC（热带对流年）数据集和数值建模实验。该项目由以下三个主要研究组成部分组成。首先，将应用新开发的涡流动能（EKE）预算诊断，以调查天气涡流与慢变化的背景平均状态和MJO流动在影响MJO各个阶段的正压和斜射能量转换方面的作用。其次，研究人员将检查非线性整流的季节内表面潜热通量（LHF）及其与MJO构建的暂时和空间相的关系。第三，研究人员将检查延伸SSV调节季节内明显的热量和水分来源，以及非线性涡流转运（包括2天波和中尺度对流系统的效果）如何向MJO发挥高档反馈。海洋“变红”过程，高频大气变异性会影响季节内SST，还将通过一系列海洋一般循环模型实验进行研究。将特别研究以下两个非线性矫正过程，表面风应力/热通量和海洋非线性广告过程的非线性矫正将被特别研究。研究的影响包括对改善属于综合性时间到现状的全球气氛中境内范围内境内范围内境内的热带构造的热带构造的结构和可变性的贡献，可能会导致范围/地区的天气范围。在热带和热带地区，都支持下季节的预测潜力。