Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm

Abstract

Data from the Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) network of polarimetric X-band radars are used to observe a convective storm. A fuzzy logic hydrometeor identification algorithm is employed to study microphysical processes. Dual-Doppler techniques are used to analyze the 3D wind field. The scanning strategy, sensitivity, and low-level scanning focus of the radars are investigated for influencing bulk hydrometeor identification and dual-Doppler wind retrievals. Comparisons are made with the nearby S-band polarimetric Next Generation Weather Radar (NEXRAD) prototype radar (KOUN), for consistency. Lightning data are used as an independent indicator of storm evolution for comparison with radar observations.A new methodology for retrieving the vertical wind utilizing upward and variational integration techniques is employed and shown to illustrate trends in mean wind, with particularly good results at low levels. IP1 observations of a case on 10 June 2007 show the development of the updraft, subsequent graupel echo volume evolution, and a descending downdraft preceded by significant graupel in the midlevels, with updraft and graupel volumes leading the onset of lightning. Many of these trends are corroborated by KOUN. The high temporal resolution of three minutes and near-ground sampling provided by IP1 is integral to resolving upand downdrafts, as well as hydrometeor evolution. IP1 coverage of the upper levels is diminished compared to KOUN, impacting the quality of the dual-Doppler derived vertical winds and ice echo volumes, although the low-level coverage helps to mitigate some errors. However, IP1 coverage of the low-to midlevels is demonstrated to be comparable or better than coverage by KOUN for this storm location.

Polarimetric Doppler Radar Analysis of Organization of a Stationary Rainband with Changing Orientations in July 2010

“…Figure 19 shows that the distinct outflows associated with deep convective cells, including graupel particles, begin to appear from the end of Period A, around 1730 LST in the northern area. The graupel leading the low-level downdraft was also reported by Dolan and Rutledge (2010). Meanwhile, intensification of low-level southerly wind begins to appear from 1750 LST (Fig.…”

“…Recent studies using polarimetric radar measurements revealed the presence of graupel particles in convective cells in association with stronger updrafts and downdrafts (Park et al 2009;Dolan and Rutledge 2010). Dolan and Rutledge (2010) demonstrated that graupel generated within updraft area led the strong downdraft by several minutes in convective cells. Adams-Selin et al (2013) simulated convective systems with and without graupel.…”

Weather radar rainfall data in urban hydrology

“…Seo and Krajewski, 2010;Sharif and Ogden, 2014; or applying adaptive scanning strategies to capture the most intensive part of a storm with a high degree of detail (e.g. Dolan and Rutledge, 2010).…”

Theory and Observations of Controls on Lightning Flash Size Spectra

“…(e.g., Boccippio 2002;Wiens et al 2005;Kuhlman et al 2006;Tessendorf et al 2007; Barthe et al 2010;Deierling et al 2008;Deierling and Petersen 2008;Dolan and Rutledge 2010). The theme of how lightning couples to the convective plume is extended and synthesized here by considering eddyscale aspects of the plume structure.…”