RAPID: The GNSS Instrument System for Multistatic and Occultation Sensing (GISMOS) for Future Application to Precipitation Processes in Atmospheric River Events

大气河流负责将大量的水分带到北极，太平洋西北部和加州海岸线，导致强降水。目前还不完全清楚水分和气溶胶的垂直分布如何影响降水过程，特别是在降水效率和到达北方纬度并可与冷锋相互作用的水分通量方面。这将是有利的，能够使用的水分和降水的垂直分布的直接信息，以调查在这类事件的物理参数化模型的敏感性。虽然模型调整方法在当前气候中总体上是成功的，但随着气候变化，不一定会出现同样的情况。因此，在这些高水汽通量地区同时测量大尺度水汽和水汽的垂直分布，为预测降水提供更可靠的依据至关重要。利用GPS无线电掩星进行的空中湿度测量可以作为一种有针对性的观测方法，与其他空中和卫星观测相结合，为解决这一科学问题提供数据。最近的模拟表明，通过对左旋圆偏振（LHCP）GPS信号测量的前向散射效应，有可能探测到大雨滴的存在。 如果这可以证明是可行的，那么机载GPS无线电掩星测量不仅可以从正常的RHCP信号中提供大气活动剖面，而且还可以从差分LHCP减去RHCP信号中提供强降水和降水率存在的迹象。作为朝这个方向迈出的第一步，将利用现有的GISMOS仪器在强降水事件期间进行一些初步测量。 2014年11月至11月，美国航天局DC-8号飞机在从加州飞往智利的航班上进行飞行操作，然后在德雷克海峡进行横断面测量，这将提供这样一个机会，在可能有强降水的热带辐合区上的横断面上测试使用替代天线配置进行的数据收集。 在2014年8月的飞行测试也将提供一种手段，为执行一些必要的维护GISMOS仪器，准备它为未来的工作任务，致力于大气河流事件，并使用更大的NSF community.Intellectual优点：尝试开发这种原始的和创新的使用GISMOS降水传感同时与湿度传感高垂直分辨率将推进有效的降水过程建模。更广泛的影响：整修和准备GISMOS仪器，供国家科学基金会继续使用，作为HIAPER成套仪器的一部分，通过为低层大气观测设施作出贡献，加强了研究基础设施。这些改进使GISMOS的GPS/INS组件与GPS遥感组件分开使用成为可能，并使使用GV飞机的任何研究人员直接受益，大大提高了现有仪器的精度。

Atmospheric rivers are responsible for bringing large quantities of moisture to the arctic, Pacific Northwest, and California coastlines, leading to heavy precipitation. It is not fully understood how the vertical distribution of moisture and aerosols affects precipitation processes, especially in terms of precipitation efficiency and the flux of moisture that reaches northern latitudes and is available for interaction with cold fronts. It would be advantageous to be able to use direct information on the vertical distribution of moisture and precipitation to investigate the sensitivity of the models to the physics parameterizations during this type of event. While the model tuning approach has in general been successful for the current climate, it is not necessarily expected that as climate changes, the same will be true. Therefore, to make simultaneous measurements of the large-scale vertical distribution of hydrometeors and moisture in these regions of high moisture flux to have a more reliable basis for predicting precipitation is crucial. Airborne measurements of moisture using GPS radio occultation can be used as a targeted method of observation to provide data to address this scientific question, in concert with other airborne and satellite observations.Recent simulations indicate the possibility of detecting the presence of large raindrops from forward scattering effects measured on left-hand circularly polarized (LHCP) GPS signals. If this can be shown to be feasible, then airborne GPS radio occultation measurements could not only provide refractivity profiles from normal RHCP signals, but also provide indications of the presence of heavy precipitation and precipitation rates from differential LHCP minus RHCP signals. As a first step in this direction, some preliminary measurements during heavy precipitation events will be made using the existing GISMOS instrument. A NASA DC-8 flight operation in October-November 2014 on flights from California to Chile, then transects across the Drake Passage will provide such an opportunity, which would test data collection with alternate antenna configurations, on the transect over the inter tropical convergence zone where heavy precipitation is likely. Flight tests during August 2014 would also provide a means for performing some needed maintenance on the GISMOS instrument, to prepare it for future work on missions dedicated to atmospheric river events, and for use by the larger NSF community.Intellectual Merit:The attempt to develop this original and innovative use of GISMOS for precipitation sensing simultaneously with moisture sensing with high vertical resolution will advance effective modeling of precipitation processes. The project will focus on the physical phenomenon of atmospheric rivers, an important process of moisture transport from the tropics to mid-latitudes.Broader Impacts:The refurbishing and preparation of the GISMOS instrumentation for continued use by the NSF community as part of the HIAPER suite of instrumentation enhances infrastructure for research by contributing to the Lower Atmospheric Observing Facility. The modifications make it possible to use the GPS/INS component of GISMOS separately from the GPS remote sensing components, and directly benefit any researcher using the GV aircraft by substantially increasing the accuracy over the existing instrumentation.