Concurrent Radar and Aircraft Measurements of Florida Thunderstorm Cirrus Clouds

Observations from summer 2015 and 2019 field projects near the Cape Canaveral Air Force Station in Florida are analyzed. The highly-instrumented North Dakota Citation Research Aircraft and the U.S. Navy’s Mid-Course Radar (MCR), a unique, high-resolution radar on the Atlantic coast of Florida, obtained concurrent measurements of thunderstorm anvil cirrus clouds. The MCR alternatively transmits two waveforms, a lower-resolution (narrowband) beam and a high-resolution (wideband) beam with along-beam range resolutions of 37 m and 0.5 m, respectively. A specialized MCR scanning strategy allows the MCR to track the aircraft using the downlinked position information from the aircraft to set the wideband beam ahead of the aircraft in real-time, thus obtaining concurrent, high-resolution in-situ and remote observations. Equivalent radar reflectivity factor is derived from effective liquid particle sizes and concentrations from the aircraft imaging probes and total particle mass from the Nevzorov Water Content Probe, and the associated uncertainties are calculated at 1 and 10 second averaging intervals. The derived equivalent reflectivity factor is compared with the wideband reflectivity factor and its associated uncertainties at the same averaging intervals. A case study is presented from 01 August 2015 where an average of 95 % of examined 1-second averaged values of derived reflectivity factor and observed wideband reflectivity factor agree within their respective uncertainties across the sampled range of -20 to 20 dBZ. However, the agreement decreases to 71 % of the values for 10 second averaging. Additional flights provide observations that include a wider range of thunderstorm cloud microphysical conditions which enable a vertical profile of water content, with corresponding uncertainty, to be obtained using the MCR’s wideband reflectivity factor.