Observational requirements for radar insights into convective updraft microphysics and dynamics
19 March 2018
1:30 PM - 3:30 PM
35
Marcus van Lier-Walqui, Matthew Kumjian, Zhe Feng
Breakout Description
The aim of this session was to explore the observational requirements for addressing outstanding areas of uncertainty in the understanding of deep convective microphysics. This session was, in part, motivated by discussions that occurred at the 2017 ARM Radar Science Workshop, and a white paper that recommended new baseline scan strategies for the ARM SGP X-SAPR network --- changes that were aimed at the lack of high spatial- and temporal-resolution radar observations of convective updraft life cycles. Both modelers and observational experts participated, allowing for discussion of model insights into observational requirements, as well as current and future radar capabilities.
Main Discussion
Very few (only one or two) participants had used X-SAPR data in its previous incarnation (10-minute PPI volumes), and a large percentage of participants expressed interest in new scanning strategies for the X-SAPR network. There was strong interest in ARM allocating scanning polarimetric radar resources towards higher temporal- and spatial-resolution, limited-area scanning during convective weather, and considerable interest in this being a target for long-term investment in radar resources. Discussion also brought out possible additional applications for this observational focus --- C. Williams brought up applicability to illuminating the transience of rain microphysical properties observed by profiling radars, and others noted that these scanning strategies could help reveal details of ice detrained from the top of deep convective updrafts.
Key Findings
It was widely agreed upon that WSR-88D-style scan strategies (volumes from PPIs every ~5 min) would be inadequate for resolving details of evolution of micorphysical processes with updrafts (S. Collis). Furthermore, in tests within an OSSE framework, it was noted that traditional scanning strategies used in dual-Doppler wind retrievals strongly underestimate convective updraft properties, and that up to four radars scanning rapidly (~ 1-min volumes) were necessary to accurately resolve the full updraft (M. Oue). Model studies, meanwhile, suggest that similar temporal resolutions, and spatial resolution on the order of 100 m, might be necessary to resolve the scale of the updraft thermal structure (H. Morrison). Such resolution is possible with advanced radars such as phased-array radars or the Atmospheric Imaging Radar (which is able to produce sector volumes at 10-s resolution --- B. Isom), but can be approached with the ARM X-SAPR network over limited domains (10 elevations, 90-degree sectors @ 100 seconds --- A. Thiesen).
Issues
None
Needs
High-resolution polarimetric radar observations of deep convective storms for evaluation.
Decisions
The community consensus is to move forward with the plan for improving X-SAPR scanning strategies. Some in the room were interested in discussing future improvements to scanning strategies in winter/cold-season precipitation.
Future Plans
Analyze preliminary data from X-SAPR performing limited-area sector scans, analyze 1-2-minute sector volumes taken using NOAA NWS KOUN radar. Continue discussions with ARM radar engineers about any data quality or radar performance issues.
Action Items
Notify interested investigators when preliminary X-SAPR data with new scan strategies is available.
