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: 2303504
• 负责人: Angel Adames-Corraliza
• 金额: $ 33.69万
• 依托单位: University of Wisconsin-Madison
• 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=2303504&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征是偶尔出现一大片多云天气，从印度洋沿着赤道向东缓慢移动到太平洋，导致一两个月内雨天交替。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加州海岸登陆的大气河流的可能性。鉴于其缓慢的传播和对全球的影响，MJO是次季节时间尺度上可预测的天气和气候变化的主要驱动因素。自1971年发现以来，MJO自然一直是一个深入研究的主题，但我们对它仍然缺乏令人满意的了解，用于天气预测和气候模拟的模型很难描述它。MJO的一个谜团是它对其上方平流层风向的依赖，平流层风向在某种程度上由东向西风变化，这种变化被称为准两年振荡(QBO)。MJO在QBO的东风阶段更为活跃，其特点是赤道平流层下部温度较低，同时伴随着东风。一些研究人员认为，较低的温度通过降低对流层上层的稳定性从而加强与MJO相关的对流，从而促进了MJO。但该奖项的首席研究人员(PI)假设，较低的温度之所以重要，是因为它们促进了卷云，而卷云由于其红外辐射反馈而有利于MJO。卷云假说是由QBO影响的几个方面引起的，其中一个方面是这种影响不会出现在1980年之前。1980年的开始是有道理的，因为1980年之前平流层较暖，因此卷云不太容易受到偏东QBO阶段的冷却效应的影响。QBO和MJO的关系是通过各种活动来探索的，其中包括对几个卫星任务(包括COSMIC、CALYPSO、MLS)和再分析数据集的分析、气候模式模拟和一个简单的线性模式(基于AGS-2201441中使用的模式)。鉴于MJO对世界各地天气的影响，以及如果更好地了解MJO的行为，MJO可以预测的可能性，这项工作具有社会和科学价值。项目负责人举办了一系列网络研讨会，与MJO研究界交流研究成果，牵头的项目负责人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讲习班。此外，该项目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智力优势和更广泛的影响审查标准进行评估，被认为值得支持。