Radar Observations of the Cloud Population in the Developing Madden-Julian Oscillation

马登-朱利安涛动（DYNAMO）场运动的动力学是2011年底/ 2012年初在印度洋进行的一项国际实验——印度洋季节内变率合作实验（CINDY2011）的美国组成部分。DYNAMO的总体目标是加快对印度洋MJO形成的关键过程的理解，并改进对MJO的模拟和预测。实地考察活动将包括多部雷达、大气探测站点、一架研究飞机、多艘研究船和海洋测量。DYNAMO的三个主要假设是：1)只有当湿层在MJO尺度上足够深时，深层对流才能组织成MJO对流包络；2)不同阶段的特定对流种群对MJO的形成至关重要；3)阻挡层、风切变混合、浅层温跃层和混合层夹带通过控制上层海洋热含量和海温对印度洋MJO的形成起重要作用。该合同将允许从甘岛收集和分析S-PolKa和其他超级站点雷达数据。这些数据将与补充的观测数据相结合，以获得云群和湿度场的关键经验特征，从而有助于验证DYNAMO假设1和2。DYNAMO期间S-PolKa的部署将由该研究小组领导。该研究包括四个主要部分：1)利用现有的雷达数据，通过展示每种类型的云组成整个云群的数量，以及这些不同的云混合如何在MJO开始从开始前、开始到开始后的阶段中结合产生净加热、水分和动量反馈，来解决假设II。2)通过密切观察云与发展中的环境湿度剖面之间的直接界面，在每个初始阶段和阶段之间的过渡阶段，获得MJO云种群特征在湿度场补给过程中如何演变的数据。3)通过比较几种模型对MJO启动期间云人口的描述来检查它们的性能。4)确定MJO起始云群与其他海洋热带地区观测到的雷达回波群是否一致或不同。这项工作的更广泛影响包括多名研究生参与实地研究，以及对DYNAMO运动更广泛目标的贡献，以提高对热带对流的理解，MJO的可预测性，以及MJO对美国和其他地区天气的下游影响。

The Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign is the US component of an international experiment in late 2011/early 2012 in the Indian Ocean, the Cooperative Indian Ocean Experiment on Intraseasonal Variability (CINDY2011). The overarching goal of DYNAMO is to expedite understanding of processes key to MJO initiation over the Indian Ocean and to improve simulation and prediction of the MJO. The field campaign will include multiple radars, atmospheric sounding sites, a research aircraft, multiple research vessels, and oceanic measurements. The three main hypotheses of DYNAMO are: 1) Deep convection can be organized into an MJO convective envelope only when the moist layer has become sufficiently deep over a region of the MJO scale; the pace at which this moistening occurs determines the duration of the pre-onset state, 2) Specific convective populations at different stages are essential to MJO initiation, and 3) The barrier layer, wind- and shear-driven mixing, shallow thermocline, and mixing-layer entrainment all play essential roles in MJO initiation in the Indian Ocean by controlling the upper-ocean heat content and SST, and thereby surface flux feedbackThis award will allow for the collection and analysis of S-PolKa and other supersite radar data from the island of Gan. This data will be combined with complementary observational data to acquire key empirical characteristics of the populations of clouds and the humidity field to contribute to the testing of DYNAMO Hypotheses 1 and 2. The S-PolKa deployment during DYNAMO will be led by this research team. The study consists of four main parts: 1) Use of the available radar data to address Hypothesis II by showing how many clouds of each type make up the full cloud population, and how these different mixes of clouds combine to produce net heating, moisture, and momentum feedbacks as the MJO initiation progresses from the pre-onset, to onset, to post-onset stages. 2) Obtain data that show how the characteristics of the MJO cloud population evolve during the recharging of the humidity field by closely examining the direct interface between clouds and the developing environmental humidity profile in each of the initiation stages and in the transitions between stages. 3) Examine the performance of several models by comparing their depiction of the cloud population during the MJO initiation. 4) Establish whether the MJO initiation cloud population is consistent with or differs from radar echo populations observed in other parts of the oceanic tropics.The broader impacts of the work include the involvement of multiple graduate students in field research, and the contribution to the broader goals of the DYNAMO campaign to improve understanding of tropical convection, the predictability of the MJO, and downstream effects of the MJO on weather in the United States and other areas.