The Global Precipitation Measurement (GPM) mission is an international network of satellites that will provide next-generation global observations of rain and snow. Building upon the success of the Tropical Rainfall Measuring Mission, the GPM concept centers on the deployment of a core satellite carrying an advanced radar / radiometer system to measure precipitation from space. The dual-frequency precipitation radar (DPR) will be operating at Ku and Ka band. The GPM core observatory is scheduled for launch in early 2014.
The D3R is a fully polarimetric, scanning weather radar system operating at the same frequency as DPR, covering a maximum range of 30 km. The D3R is the part of GPM ground validation activities. It supports GPM pre-launch algorithm development and contributes to post-launch precipitation product validation.
In GPM pre-launch era, NASA Jet Propulsion Lab developed the second-generation Airborne Precipitation Radar (APR-2) as a prototype of an advanced dual-frequency space radar which emulates DPR on board the GPM core satellite. APR-2 was deployed in the GCPEx campaign (the GPM Cold-season Precipitation Experiment) located in Ontario, Canada. GCPEx is the most recent campaign that conducted in the year 2012 with the focus on snow precipitation.
Both D3R radar and APR-2 radar were deployed in the GCPEx experiment, which provides us an opportunity to study and cross-validate the microphysics retrieved from different radar systems. In this paper, measured dual-frequency ratio (DFRm) profiles obtained from airborne radar will be extensively studied. APR-2 radar pointing downward has fine vertical resolution around 30m.The slope of the DFRm profile with respect to height will be studied based on different snow models. Microphysics such as snow density and size can be inferred from DFRm profile characterizations. To cross validate the snow microphysics retrieved from airborne radar, well aligned observations from D3R radar will be applied. D3R radar has fine range resolution and, besides measured dual-frequency ratio, D3R radar carries horizontal looking dual-polarization information such as Zdr, Kdp and ρhv, all of which are very useful in hydrometeor detection and snow retrieval. The comparison results will be presented.
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