Integration of observations for detection of aircraft icing conditions during AIRS2: Comparisons of microphysical parameters

Alliance Icing Research Study II (AIRS2) data have been used to better understand aircraft icing processes and the retrieval of microphysical parameters from satellite observations. AIRS2 was conducted in the southern Ontario-Quebec region in the winter of 2003-2004. Aircraft in-situ measurements were compared with retrievals obtained from GOES satellite observations and with observations obtained from ground-based platforms, including microwave radiometers and an X-band vertical pointing Doppler radar. The in-situ data include liquid and ice particle number concentration, water content, particle effective size, temperature, and icing-rate. The case studies used in this work include data from (1) the February 5-7 case representing mixed phase cloud conditions over a large area covering the Ohio region to NE of the Great lakes area and (2) the November 19 case that was also related to a cold front. The maximum LWC during Feb. 5-7 case was measured at about 0.5 g m-3 at –13°C and 0.3 g m-3 at –20°C. The LWC also reached 0.5 g m-3 on Nov. 19 case but cloud tops were glaciated. The pilots characterized these cases as having severe icing conditions. The NASA GOES icing scheme indicated icing for the Feb. 5-7 case but not for the Nov. 19 case. The McGill vertically pointing radar observations also indicated that icing was consistent with the in-situ data for both cases. The results suggested that observations should be integrated in order to better understand remote sensing retrievals and icing environments.