Disdrometer derived Z-S relations in South Central Ontario, Canada

In support of NASA's Global Precipitation Measurement (GPM) mission ground validation program, NASA's two laser optical disdrometers (Parsivel) and Colodaro State University (CSU) two-dimensional video disdrometer (2dvd) were deployed to a well-equipped precipitation observation site in South Central Ontario, Canada. The instruments were collocated and have been operating since late November 2006. So far, there have been numerous lake effect and synoptic winter storms over the site. In one event, parsivel disdrometers recorded 50 cm of snowfall. In addition, there have been at least 10 storms where the snow accumulation exceeded 4 cm.

The leading objective of this study was to derive the radar reflectivity versus snowfall rate relations employing the parsivel and 2dvd measurements for selected cases. To determine the radar reflectivity in snow, the density of snow is required. We plan to obtain bulk density of snow through matching the disdrometer and gauge measurements where the gauges provide the water equivalent of snow. The field site offers several types of gauges including Geonor weighing bucket gauge, heated tipping bucket gauge, and experimental hot plates. In addition, Canadian radar disdrometer (POSS) and visibility sensors provide information on the melted precipitation rate. Upon availability, we plan to use all instruments to determine the radar reflectivity and compare it with C-band radar measurements. The radar is located about 35 km from the site. It should be noted that the density of snow is a challenging but also a key parameter to validate the radar based snow measurements.

The field site, which is known as Centre for Atmospheric Research Experiments (CARE), is an atmospheric research facility operated by the Air Quality Research Branch of the Meteorological Service of Canada and is located 80 km north of Toronto, Ontario, Canada in a rural agricultural and forested region. During the past three winters, a field campaign was conduced in support of Canadian CloudSat/CALIPSO validation project (c3vp). However, 2006-07 winter was the first since the satellites were in orbit. The coordinated efforts of aircraft missions over the CARE facility during the Intensive Operation Periods will enhance our understanding of cold cloud microphysics.