OLYMPEX Canada

The OLYMPEX project was a continuation of the rich history of collaborating between Environment and Climate Change Canada (ECCC) and NASA on ground validation activities in support of space-based missions. There is an existing collaborative agreement between the organizations to cover this type of activity (prior such programs being the Canadian CloudSat CALIPSO Validation Experiment in the winter of 2006/07 and the GPM Cold Season Precipitation Experiment in 2011/12). The ECCC primary contribution to OLYMPEX was to support the validation of GPM products in complex terrain by monitoring the precipitation processes occurring on the leeside of the Olympic Mountains. It was an ideal complement to similar measurements made by NASA and NSF facilities on the windward side of the Olympic Mountains. The core activity was the deployment of a dual polarization X-band portable scanning radar to the southern tip of Vancouver Island on Canadian Forces Base (CFB) Esquimalt Albert Head camp. This site has a direct line of site at a distance of 45 km to Hurricane Ridge on the Olympic Peninsula where a suite of in-situ and remote sensing sensors were located. Other instrumentation co-located with the X-band radar were ground sensors to measure the characteristics of the falling precipitation. This included a visibility sensor (Vaisala FD12P), a Parsivel optical disdrometer, a Pluvio2 weighing gauge, and a compact weather station giving temperature, pressure , wind, and solar radiation. At the University of Victoria main campus, approximately 15km away from the radar, an upper air sounding unit was operated for continuous launches during the field campaign. The radar operated continuously during of the field campaign from November 13, 2015 onwards. The radar scanning was carried out with a scan strategy that had a 5 min repeat time, The series of scans in each cycle were 5 vertical cross sections (range height indicator scans) centred on Hurricane Ridge followed by 3 low level azimuthal scans (plan position indicator scans) on elevation angles of 1,5, 2.5 and 5.0 degrees out to a range of 100 km. The specific ECCC objectives for OLYMPEX are a) To contribute to microphysical studies of the precipitation formation mechanisms around and to the lee of Hurricane Ridge in order to document microphysical properties at high elevations and the variability of microphysical processes within and above the rain/snow transition zone. b) To evaluate GPM products in complex terrain – coast/water/orography. Participation in OLYMPEX will enable an assessment of the quality of the measurements for the Canadian climate and enhance the development of applications that makes use of this information. c) To support goals related to High Resolution Deterministic Prediction System (HRDPS) (2.5 KM grid of the Canadian Meteorological Centre and data assimilation studies that use the West Coast version of High-Resolution Ensemble Kalman Filter (HREnKF) Forecasting system. The radiosonde ascents and radar measurements were able to document the precipitation processes occurring on the leeside. The vertical cross section in particular provided insight into the vertical structure of the microphysical properties at high elevations over Hurricane Ridge. Despite being located in the so-called rain shadow of the Olympics, there were a number of events whose precipitation patterns extended well to the lee of the mountains. At least one event was characterized by an outflow from the British Columbia mainland that put the northern side of the Olympics on the windward side. Overall, there were13 daily precipitation totals at Albert Head in excess of 10 mm and 4 in excess of 30 mm. Data collection is ongoing until mid-March, 2016. The presentation will describe early analyses of the data collected. It will demonstrate its ability to extend the OLYMPEX observations to the lee side of the Olympic Mountains and in turn address to the specific stated objectives.