Ph.D., Atmospheric Sciences, University of Washington, 1990
My work addresses the mesoscale dynamics of precipitating systems, boundary-layer circulations over flat and complex terrain, cloud dynamics, and cloud and precipitation radars. The main tools have been the Wyoming Cloud Radar (WCR) and the UW King Air aircraft.
Dynamics and microphysics of orographic precipitation (since 2006)
We have been taking the UW King Air with radar and lidar over Wyoming mountain ranges since 2006, to study natural orographic precipitation processes and snowfall enhancement by means of glaciogenic seeding of orographic clouds. The most intensive effort to date was ASCII (AgI Seeding of Clouds Impact Investigation), an NSF-funded campaign in 2012-13 over the Sierra Madre and Medicine Bow Ranges that also deployed a dual-pol DOW radar at 10,000 ft above sea level. We used the same observational tools in the 2017 SNOWIE project. Another winter campaign is in the planning stage, in Utah.
Dynamics of radar fine-lines in the pre-convective continental boundary layer (since 2002)
We used data collected in IHOP (International Water Vapor Experiment, May-June 2002, funded by NSF), in particular the UW King Air and WCR data, to examine a vertical velocity bias found in radar data of the optically-clear convective boundary-layer, the dynamics of coherent eddies in the convective boundary-layer, the fine-scale structure of boundaries such as cold fronts and drylines, and convective initiation mechanisms. In a future campaign, we hope to further study dryline formation (incl. land surface processes) and dryline fine-scale dynamics.
Boundary-layer circulations over relatively warm water (since 2004)
Through NSF, NASA, and DOE funding, we have been studying the dynamics and cloud microphysics of clouds that form when a cold airmass blows over open water. We used the UW King Air and WCR over Lake Michigan in 2004 and over Lake Ontario in 2013-14. In 2019-20, a DOE ARM Mobile Facility was deployed along the northern Norwegian coast to study this cloud regime over the Norwegian Sea. And in 2024, we hope to take the NCAR C-130 aircraft over the same sea, up to the Arctic ice, with a host of radars and lidars on board.
Dynamical processes in orographic cumuli (since 2006)
Data collected in CuPIDO (also funded by NSF) were used to study the dynamics of towering cumuli over the Santa Catalina Mountains in Arizona during their summer monsoon, and the interaction of cumulus convection with the topographically-controlled mesoscale circulation. Again we used the UW King Air with WCR, plus soundings, surface stations, digital photogrammetry, profiling remote sensors, and numerical modeling. We currently are planning a project to take the new UW King Air with radars and lidars to the European Alps to study summertime venting of BL air.