HR: 14:25h
AN: A13E-04    [Abstracts]
TI: Using measurements of atmospheric trace gases to quantify precipitation scavenging of CCN
AU: Avey, L
EM: lavey@met.utah.edu
AF: Department of Meteorology University of Utah, 135 S 1460 E Rm 819, Salt Lake City, UT 84103 United States
AU: * Garrett, T J
EM: tgarrett@met.utah.edu
AF: Department of Meteorology University of Utah, 135 S 1460 E Rm 819, Salt Lake City, UT 84103 United States
AU: Palmer, P
EM: pip@env.leeds.ac.uk
AF: School of Earth and Environment, University of Leeds, Leeds, LS LS2 9JT United Kingdom
AU: Brock, C
EM: cbrock@al.noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Ryerson, T
EM: Thomas.B.Ryerson@noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Neuman, A
EM: andy.neuman@noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Holloway, J
EM: jholloway@al.noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
AB: A simple representation of aerosol-cloud interactions is a feedback loop, in which production of anthropogenic cloud condensation nuclei (CCN) increases cloud droplet concentrations, suppresses precipitation, and in turn reduces wet scavenging of CCN. The last of these links is the most apparent to the casual observer: after a storm, the air clears and the car needs a wash. But while obvious, this process is very difficult to quantify without detailed models because of the complexities of precipitation production, and ambiguities associated with separating the effects of atmospheric mixing and wet scavenging on concentrations of CCN. Using airborne data from the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) project, we show that measured ratios of soluble and insoluble trace gases provide a useful indicator for identifying air masses that have been wet scavenged. For this purpose, we use ratios of nitric acid (HNO3) scaled to anthropogenic carbon monoxide (CO). HNO3, a respective tracer of anthropogenic activity, is highly soluble and removed efficiently by wet scavenging. CO is insoluble and has a lifetime about a month. We show that observed ratios of HNO3/CO are negatively correlated with precipitation production rates, and can be used to estimate the fractional removal of CCN by precipitating clouds.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005