HR: 09:15h
AN: A51C-04    [Abstracts]
TI: Measurements and application of cloud condensation nuclei spectra
AU: * Hudson, J G
EM: hudson@dri.edu
AF: Desert Research Institute, 2215 Raggio Pkwy, Reno, NV 89512-1095 United States
AU: Mishra, S
EM: subhashree.mishra@dri.edu
AF: Desert Research Institute, 2215 Raggio Pkwy, Reno, NV 89512-1095 United States
AB: Simultaneous detailed airborne measurements of cloud condensation nuclei (CCN) spectra from the two Desert Research Institute (DRI) CCN spectrometers (Hudson 1989) are presented. In order to accurately measure the entire cloud supersaturation (S) range (i.e., 1.2-0.02%) these instruments were operated at different S ranges. Agreement between these instruments in the overlapping S range centered about 0.1% provided confidence in these difficult measurements. Extensive spatial and temporal measurements are presented from two projects: one continental, AIRS2 over the Great Lakes area, and one maritime, RICO over the Caribbean. Comparisons of nearby cloud droplet concentrations with these CCN spectra yield estimates of cloud S. Plots of droplet concentrations versus liquid water contents compared with estimates of adiabatic liquid water contents can yield estimates of measured adiabatic droplet concentrations (Hudson and Yum 2001, 2002). Alternatively these CCN spectra can also be used as input to an adiabatic model, which along with measured updraft velocity yields predictions of adiabatic cloud droplet concentrations (e.g., Yum et al. 1998). Comparisons of these predictions with measurements of cloud droplet concentrations can yield estimates of the degree of cloud adiabaticity-i.e., degree of out of cloud mixing. Comparisons with the adiabatic cloud droplet concentrations noted in the last paragraph can yield estimates of the condensation coefficient, which is also a fundamental input to the adiabatic model. This could be altered by anomalous aerosol. The effect of anthropogenic CCN on cloud radiative and precipitation properties is the largest climate uncertainty--the indirect aerosol effect. Hudson, J.G., 1989: An instantaneous CCN spectrometer. J. Atmos. & Ocean. Techn., 6, 1055-1065. Hudson, J.G., and S.S. Yum, 2001: Maritime-continental drizzle contrasts in small cumuli. J. Atmos. Sci., 58, 915-926. Hudson, J.G., and S.S. Yum, 2002: Cloud condensation nuclei spectra and polluted and clean clouds over the Indian Ocean. J. Geophys. Res., 107(D19), 8022, doi:10.1029/2001JD000829. Yum, S.S., J.G. Hudson, and Y. Xie, 1998: Comparisons of cloud microphysics with cloud condensation nuclei spectra over the summertime Southern Ocean. J. Geophys. Res., 103, 16,625-16,636.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution--urban and regional (0305)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly