Message of Thursday, August 5, 1999 Dear Everybody: The conveners of the Indirect Aerosol Effects Session at the INDOEX meeting in Utrecht (/Desbois/Heymsfield/Twohy) solicit titles and abstracts for our session. We would like to ask each of you who wishes to present a talk or poster to send to Andy a brief abstract ASAP. We will go over them and try to put together a balanced, focused session that covers the major findings. The inserts and attachment identifies the C130 flights and their ranking in terms of how well they may address the indirect effect. The highest ranked cases include a combination of gradient flights and intervals during polluted flights. We ask the Citation group to put together a similar summary rating of the cases they flew in-cloud with the FSSP, as well as any cases which may pertain to the indirect effect? Sincerely, Andy Heymsfield Ratings (link to Summary of INDOEX Cloud Flights (Non-Gradient): We rated each flight according to how well it can be used to address the indirect effect. We felt that CN, CCN, and aerosol composition data in the subcloud environment as well as in-cloud measurements could be used to establish a linkage in the physical processes which gives rise to the indirect (Twomey) effect. We therefore rated highly those cases which contained measurements both in-and below-cloud at times which were relatively close. For the gradient flights, good radiation measurements (usually on the return leg) were of importance as they provide a means of inferring the radiative consequences of the indirect effect. We gave high values to those gradient flights (a perfect score was assigned a value of 10) that contained sub-cloud and in-cloud data throughout much of the duration of the N-S transit, and had radiation measurements on the return leg; two of the gradient flights had scores of 10. The flight of 24 March, while not highly rated as a gradient flight, scores high marks for getting clean cloud closure. While we gave marks of 7 or 8 to several of the non-gradient flights, we recommend focusing on 21 March, 7 March followed by 27 Feb and 16 March for the "polluted" clouds. Note that on several of these days, there are discrete times of interest. Also note that there were several non-gradient flights whose ratings of "nix" mean that they are of little interest.
RATINGS 16 Feb Nix 18 Feb Nix 20 Feb 10 Gradient flight, possible FSSP problem 24 Feb 10 Gradient 25 Feb Nix 27 Feb 7--8, particular times: 0945-1030, 1245-1315 28 Feb Nix 4 March 7 Gradient 7 March 8, particular times: 0730-1115 9 March Nix 11 March 8 Gradient 13 March 6, Citation intercomparison 16 March 7 18 March 7, multiple penetrations of Cb. 19 March 7, particular times: 0600-0830, 0900-1130 21 March 8, particular times: 0730 to 0915 24 March 6 As a gradient flight, 9 as a characterization of clean clouds 25 March 5
Andrew Heymsfield, heyms1@ncar.ucar.edu Microscale and Mesoscale Meteorology Division NCAR 3450 Mitchell Lane Boulder, Colorado 80301 303-497-8943 (w) 303-497-8171 (fax)