Studies of the Maritime Atmospheric Boundary Layer during DYNAMO

大气边界层(ABL)，通常是大气层最低的一两公里，对热带海洋上深对流云的发展有非常大的影响。马登-朱利安涛动(马登-朱利安涛动)是在印度洋上空形成的一个大的向东移动的对流区，它在马登-朱利安涛动发展中的作用是2011年马登-朱利安涛动(发电机)实地运动的主要重点(例如，见奖励1022899和1059899)。该活动收集了印度洋中部的四个岛屿站和两个船站的观测数据。该奖项的工作使用迪纳摩观测来描述热带海洋ABL的行为及其与底层海洋的相互作用。它还试图确定从岛屿站进行的观测受到岛屿效应影响的程度，这些岛屿效应不代表周围海洋上对大范围对流发展至关重要的条件。ABL属性将被检查，包括温度、湿度、稳定性、风和云量，特别关注ABL深度的日循环。在这场战役的密集观测期间，通过每三个小时发射一次气象气球来评估每天的周期。PI已经开发出一种方法，可以根据部署在岛屿和船只上的风廓线仪和无线电声学探测系统(RASS)连续观测的信噪比来确定ABL的高度。事实证明，这项技术有助于填补气球发射之间的空白，并验证气球观测捕捉到了ABL深度的完整日循环。在相同纬度、相隔10度经度的迭戈加西亚岛和科考船Revelle上收集的Profiler和RASS数据进行了比较，以检测岛屿效应。用于该活动的岛屿中有两个是环礁(第二个是马尔代夫的甘岛)，它们的陆地面积很小，但环礁周围的日温度循环相对较强，这可能会影响ABL的观测。从漩涡和从船上部署的系泊设备获得的观测被用来描述与ABL发展和随后的对流相关的海气相互作用。由于MJO影响世界各地的天气和气候的许多方式，包括墨西哥湾飓风的发展和加利福尼亚州的极端降雨事件，这项工作具有社会价值。MJO对目前的天气预报模式提出了挑战，这里所做的工作可能会改善对MJO及其影响的预报。更具体地说，该项目生成可用于模型开发的强制数据集。根据这一奖项产生的产品通过国家大气研究中心的网站向研究和运营社区公开提供。这一奖项反映了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。

The atmospheric boundary layer (ABL), typically the lowest kilometer or two of the atmosphere, has an outsized influence on the development of deep convective clouds over the tropical oceans. The role of the ABL in the development of the Madden-Julian Oscillation (MJO), a large eastward moving region of convection that forms over the Indian Ocean, was a primary focus of the 2011 Dynamics of the MJO (DYNAMO) field campaign (see for example awards 1022899 and 1059899). The campaign collected observations from four island stations and two ship stations in the Central Indian Ocean. Work under this award uses the DYNAMO observations to characterize the behavior of the tropical marine ABL and its interactions with the underlying ocean. It also seeks to determine the extent to which observations taken from the island stations are influenced by island effects which do not represent the conditions over the surrounding ocean that matter for the development of widespread convection.ABL properties to be examined include temperature, moisture, stability, winds, and cloudiness, with a particular focus on the diurnal cycle of ABL depth. The diurnal cycle is assessed from weather balloons launches that took place every three hours during the intensive observing period of the campaign. The PI has developed a method to determine the height of the ABL from the signal-to-noise ratio of continuous observations from the wind profiler and Radio Acoustic Sounding System (RASS) deployed on the islands and ships. The technique could prove useful for filling in the gaps between balloon launches and verifying that the balloon observations capture the full diurnal cycle of ABL depth. Profiler and RASS data collected on the island of Diego Garcia and the research vessel Revelle, at the same latitude and separated by 10 degrees longitude, are compared to detect island effects. Two of the islands used for the campaign are atolls (the second is Gan Island in the Maldives), which have minimal land area but surround lagoons with a relatively strong diurnal temperature cycle which might influence ABL observations. Observations taken from the Revelle and moorings deployed from the ship are used to characterize air-sea interactions relevant to ABL development and subsequent convection.The work has societal value due to the many ways in which the MJO affects weather and climate worldwide, including the development of hurricanes in the Gulf of Mexico and extreme rainfall events in California. The MJO presents a challenge to current weather prediction models, and work performed here may lead to improved forecasts of the MJO and its impacts. More specifically, the project generates forcing datasets that can be used for model development. Products generated under this award are made openly available to the research and operational communities through a website at the National Center for Atmospheric Research.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.