Collaborative Research: Cloud-Radiative Feedback as the Coupling Mechanism of the Madden-Julian Oscillation and Quasi-Biennial Oscillation

合作研究：云辐射反馈作为马登-朱利安振荡和准两年振荡的耦合机制

• 批准号: 2303506
• 负责人: Naoko Sakaeda
• 金额: $ 30.87万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2303506&HistoricalAwards=false
• 关键词: Collaborative; Research; Cloud; Radiative; Feedback

A remarkable feature of weather in the tropics is the occasional appearance of a vast region of cloudy conditions moving slowly eastward along the equator from the Indian Ocean to the Pacific, causing an alternation of rain and clear skies over a period of a month or two. This alternation, called the Madden-Julian Oscillation (MJO), has a variety of long-range influences, for instance it affects the chances of hurricanes in the Gulf of Mexico and landfalling atmospheric rivers along the California coast. Given its slow propagation and worldwide effects the MJO is the dominant driver of predictable weather and climate variations on the subseasonal timescale. Naturally the MJO has been a topic of intensive research since its discovery in 1971 but we still lack a satisfactory understanding of it, and models used for weather predictions and climate simulations have difficulty representing it.One mystery of the MJO is its dependence on the direction of the stratospheric winds above it, which changes from easterly to westerly in a somewhat regular progression referred as the Quasi-Biennial Oscillation (QBO). The MJO is substantially more active in the easterly phase of the QBO, which features colder temperatures in the equatorial lower stratosphere along with the easterly winds. Some researchers have argued that the colder temperatures promote the MJO by reducing upper tropospheric stability and thus strengthening MJO-related convection. But the Principal Investigators (PIs) of this award hypothesize that colder temperatures matter because they promote cirrus clouds, which favor the MJO due to their infrared radiative feedback. The cirrus cloud hypothesis is motivated by several aspects of the QBO influence, among them that the influence does not appear prior to 1980. The 1980 onset makes sense because the stratosphere was warmer prior to 1980 and thus cirrus clouds would have been less susceptible to the cooling effect of the easterly QBO phase. The QBO-MJO relationship is explored through a variety of activities including analysis of data from several satellite missions (including COSMIC, CALYPSO, MLS) and reanalysis datasets, climate model simulations, and a simple linear model (based on the one used in AGS-2201441).The work is of societal as well as scientific value given the influence of the MJO on weather around the world and the possibility that the MJO could be predictable given better understanding of its behavior. The PIs conduct a webinar series to exchange research results with the MJO research community, and the lead PI is developing an online Spanish language workshop on the role of cloud processes in weather and climate. In addition, the project provide support and training to two graduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

热带天气的一个显著特点是，偶尔会出现一大片多云的地区，从印度洋沿沿着向东缓慢移动到太平洋，在一两个月的时间里，时而下雨，时而晴朗。 这种交替被称为马登-朱利安振荡（MJO），具有各种长期影响，例如它影响墨西哥湾飓风和沿着加州海岸登陆大气河流的机会。 由于其传播缓慢和全球影响，MJO是亚季节时间尺度上可预测天气和气候变化的主要驱动因素。自然，自1971年发现以来，MJO一直是深入研究的主题，但我们仍然缺乏对它的满意的了解，用于天气预报和气候模拟的模型很难代表它。MJO的一个谜团是它依赖于其上方平流层风的方向，其从东风到西风的变化在某种程度上被称为准两年振荡（QBO）的规则进程中。 在QBO的东风阶段，MJO更加活跃，其特征是赤道平流层下部的温度较低，沿着东风。 一些研究人员认为，较低的温度通过降低对流层上部的稳定性，从而加强MJO相关的对流，从而促进MJO。 但该奖项的主要研究者（PI）假设，较低的温度很重要，因为它们促进了卷云，由于它们的红外辐射反馈，卷云有利于MJO。 卷云假说的动机是QBO影响的几个方面，其中的影响并没有出现在1980年之前。 1980年的爆发是有意义的，因为平流层在1980年之前是温暖的，因此卷云对东风QBO阶段的冷却效应不太敏感。 QBO与MJO之间的关系是通过各种活动来探讨的，包括分析来自几个卫星飞行任务的数据（包括COSMIC，CALYPSO，MLS）和再分析数据集，气候模式模拟，一个简单的线性模型（基于AGS-2201441中使用的）。这项工作具有社会和科学价值，因为MJO对世界各地天气的影响，以及MJO可能被更好地理解其行为。PI开展了一系列网络研讨会，与MJO研究社区交流研究成果，首席PI正在开发一个关于云过程在天气和气候中的作用的在线西班牙语研讨会。 此外，该项目还为两名研究生提供支持和培训。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。