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，对热带海洋上空深对流云的发展有着巨大的影响。ABL在马登-朱利安振荡（MJO）发展中的作用，这是一个在印度洋上空形成的大的向东移动的对流区域，是2011年MJO（MJO）现场活动动力学的主要焦点（例如，参见奖项1022899和1059899）。 该活动收集了中印度洋四个岛屿站和两个船舶站的观测数据。 该奖项下的工作使用的COMO观测到的热带海洋ABL的行为及其与底层海洋的相互作用的特点。 它还试图确定在何种程度上采取的观测从岛屿站的岛屿效应的影响，不代表周围海洋的条件，事项的发展广泛convention.ABL的属性进行检查，包括温度，湿度，稳定性，风，云量，特别关注的昼夜循环的ABL深度。 昼夜周期是根据在活动的密集观测期间每三小时发射一次气象气球来评估的。 研究所发展了一套方法，利用风廓线仪和无线电声学探测系统（RASS）在岛屿和船舶上进行的连续观测的信噪比来确定大气边界层的高度。 该技术可以证明是有用的，填补了气球发射之间的差距，并验证气球观测捕捉到的ABL深度的整个昼夜周期。 将在同一纬度、经度相隔10度的迭戈·加西亚和研究船Revelle上收集的剖面仪和RASS数据进行比较，以检测岛屿效应。 用于这一活动的两个岛屿是环礁（第二个是马尔代夫的甘岛），这些岛屿的陆地面积极小，但周围的泻湖具有相对较强的昼夜温度周期，这可能会影响ABL观测。 从Revelle和停泊部署从船上的观测被用来表征相关的ABL发展和随后的convention.The工作具有社会价值，由于MJO影响天气和气候的许多方式，包括在墨西哥湾的飓风和极端降雨事件的发展在加州的海气相互作用。MJO对当前的天气预测模型提出了挑战，在这里进行的工作可能会改善MJO及其影响的预测。 更具体地说，该项目生成可用于模型开发的强制数据集。 根据该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。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。

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.