18A.1 An Overview of the CAPE Weather Experiments Using the U.S. Navy Mid-Course Doppler Radar

Wednesday, 30 August 2017: 9:00 AM
St. Gallen 3 (Swissotel Chicago)
Jerome Schmidt, NRL, Monterey, CA; and P. Flatau, P. R. Harasti, and R. D. Yates

An overview is provided of the unique set of measurements obtained from a series of experiments held in the Cape Canaveral, FL region that utilized the 3MW, dual-polarization, C-band Mid-Course Doppler radar (MCR) operated by the U.S. Navy. The MCR was historically used to detect debris shed during space shuttle missions but has since been found to be well-suited for studies of local cloud systems. The utility of the MCR for cloud studies stems from the exceptionally small MCR pulse volumes produced from the narrow 0.22 degree transmitted beam width and a choice of two waveforms in which the along-range resolution could be set to either 0.5m or 37m. The higher and lower resolution waveforms were transmitted in an interleaved fashion allowing nearly simultaneous measurements of both the mesoscale and fine-scale cloud structure over range windows limited to either 400m or 75km in length, respectively. Specialized MCR scanning strategies developed as part of the field campaign further provide a unique capability for cloud studies due to the demonstrated ability to track meteorologically equipped aircraft or passing satellites (such as the A-train) in real-time. A discussion of the basic measurement strategy using the MCR and other assembled surface and aircraft assets will be presented. We highlight the use of the dual-polarization lidar to ensure precise placement of the aircraft and the limited high-resolution MCR range windows in regions of specific scientific interest. This strategy was found to be particularly useful in obtaining high-resolution measurements of the shallow circulations associated with thin mixed-phase altocumulus layers and the radar reflectivity bright band. Highlights of these two phenomena will be presented as will particularly striking cases involving the radar detection of individual raindrops in the free atmosphere. In these cases, the larger and more isolated raindrops are shown to appear in the high-resolution MCR data as peculiar, nearly linear, reflectivity “streaks” against the more uniform background reflectivity field generated by a larger population of smaller drops. The properties of the streaks are discussed and used to infer the characteristics of the underlying particles.
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