Tropical/Extratropical Interaction Mechanisms at the Intraseasonal Time Scale

该项目有可能改善北美温度和降水的分季节（2-6周）概率天气预报。对这一结果的支持是基于该小组先前关于热带天气对中纬度天气影响的研究，该研究促进了NOAA使用的概率次季节天气预报方法的发展。这个项目也将培养一名研究生成为一名独立的科学家。除了参加发表论文和发表会议报告的常规活动外，该团队还将与宾夕法尼亚州立大学科学和学校中心的人员合作，为来自低社会经济和种族多样化的宾夕法尼亚州城市和农村学区的初中和高中教师举办为期五天的亚季节到季节（S2S）预测研讨会，这些学区为科学，技术，工程和数学领域高度代表性不足的人口提供服务。教师将参加S2S预测技术的讲座，并参与相关的探究式活动。当教师在课堂上实施工作坊活动时，小组将提供后续支持。在热带地区，季内时间尺度上的主导模式是麦登-朱利安涛动（MJO），其特征是有组织的降水系统在30-70天的时间尺度上围绕热带向东传播。NOAA/气候预测中心在第3周和第4周的概率预报中使用了MJO的状态，证明了MJO对预报的重要性。虽然在过去的三十年里，在了解热带对流加热如何影响中纬度地区的天气方面取得了很大的进展，但仍有重要的未解决的问题。本项目将重点研究尚未被研究或之前很少受到关注的问题：(1)研究热带mjo相关对流如何激发罗斯比波向极传播，并影响中纬度地区的天气；(2) MJO事件中对流潜热释放的水平和垂直结构变化及其对中亚热带北太平洋关键区域的影响；(3) mjo相关对流激发的惯性重力波在将热带对流与地球上远距离的天气联系起来方面的作用，例如远相关模式。该团队还将解决以下问题：为什么远程连接模式中的高纬度成分比低纬度成分持续的时间更长？MJO激发的惯性重力波对中纬度天气有什么影响？这一主题特别重要，因为主动远程连接模式对6周后的天气有很大影响。该方法包括使用观测数据集和计算机模型计算。计算机模型将用于分离和更好地理解造成热带-温带遥相关的关键物理过程。该奖项反映了美国国家科学基金会的法定使命，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。

This project has the potential to lead to an improvement of the subseasonal (2-6 week) probabilistic weather forecasts of temperature and precipitation for North America. Support for this outcome is based upon the previous research by the team on the influence of tropical weather on mid-latitude weather, which has contributed to the development of the probabilistic subseasonal weather forecast method used by NOAA. This project will also train a graduate student to become an independent scientist. Besides participating in the usual activities of publishing papers and giving conference presentations, the team will work with personnel at Penn State's Center for Science and the Schools to conduct a five-day workshop on subseasonal to seasonal (S2S) prediction for middle and high school teachers from low socioeconomic and racially diverse urban and rural Pennsylvania school districts that serve populations highly underrepresented in science, technology, engineering, and math fields. The teachers will attend lectures on the techniques used for S2S forecasting, and participate in relevant inquiry-based activities. The team will provide follow-up support as the teachers implement the workshop activities in their classrooms.In the tropics, the dominant pattern on the intraseasonal time scale, the Madden-Julian Oscillation (MJO), is characterized by organized precipitation systems that propagate eastward encircling the tropics on a timescale of 30-70 days. The importance of the MJO for forecasting is evidenced by the use of the state of the MJO in week-3 and week-4 probabilistic forecasts by the NOAA/Climate Prediction Center. Although much progress has been made during the past three decades toward understanding how tropical convective heating influences the weather in mid-latitudes, there are still important unaddressed questions. This project will focus on questions that have not yet been investigated or have received little previous attention: (1)investigation of how Rossby waves are excited by MJO-related convection in the tropics propagate pole-ward,and impact weather in the mid-latitudes; (2) variation in the horizontal and vertical structure of the latent heat released in convections within the MJO event, and its impact in a key region, the central subtropical North Pacific; and (3) role of inertio-gravity waves excited by MJO-related convections in connecting tropical convections to weather over large distances across the Earth, e.g., teleconnection patterns. The team will also address the following questions: Why does the high latitude component within teleconnection patterns persist for a much longer time period than do their lower latitude counterparts? What is the impact of inertio-gravity waves excited by the MJO on mid-latitude weather? The topic is particularly important because active teleconnection patterns have a large influence on the weather up to 6 weeks later. The approach includes the use of observational datasets and computer model calculations. The computer model will be used to isolate and to better understand the key physical processes that are responsible for the tropical-extratropical teleconnections.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.