Retrievals of the Deep Convective System Ice Cloud Microphyscial Properties using S-band Radar
Authors
Xiquan Dong — University of Arizona
Christopher R Williams — University of Colorado, Boulder
Baike Xi — University of Arizona
Jingyu Wang —
Jingjing Tian — University of North Dakota
Category
Ice Physical and Radiative Properties
Description
This study presents two newly developed algorithms for retrieving deep convective system (DCS) ice cloud microphysical properties using S-band (3 GH) Doppler radar measurements during the Midlatitude Continental Convective Clouds Experiment (MC3E) at the ARM Southern Great Plain (SGP) site during April-June 2011.
In the first algorithm, the NEXRAD reflectivity measurements (with scanning ability), along with the total number concentration which comes from Nt-temperature relationship developed from aircraft in situ measurements, have been used in the retrieval. The 3D distributions (spatial + vertical) of ice water content (IWC) and median mass diameter (Dm) of a DCS have been developed and validated by aircraft in situ measurements during the MC3E. The in-situ measured Dm and IWC, on average, are 1.99 mm and 0.43 g/m3, while the retrieved Dm and IWC using NEXRAD reflectivity along aircraft track are 2.18 mm and 0.35 g/m3, respectively, with 0.19 mm (9.5%) and 0.08 g/m3 (18.6%) differences for all six selected DCS cases (April 25th, May 1st, 11th, 18th, 20th and 24th). For May 20th case, the aircraft measured mean Dm and IWC are 1.52 mm and 0.42 g/m3, and retrieved mean Dm and IWC are 1.36 mm and 0.23 g/m3. These results have demonstrated that the newly developed algorithm can retrieve the ice cloud microphysical properties of a DCS within the predicted theoretical error bounds.
In the second algorithm, in order to avoid using the assumption in Nt, NOAA vertical pointing S-band vertical pointing Doppler radar profilers (reflectivity, Doppler velocity and spectrum width) are used to retrieve ice cloud particle size distributions and microphysical properties with their fine operating frequency and data collection methodology. In addition, mean vertical air motion will be retrieved and provided as a side product. Because the radar is vertical pointing, only vertical profiles of IWC and Dm of a DCS will be presented, and May 20th case is also selected to validate the retrieval results. The mean Dm is 1.38 mm, only 0.02 mm more than the result from the first algorithm, and 0.14 mm less than aircraft one. The retrieved vertical air motion is around 0.54 m/s for this case.
