HR: 1330h
AN: A32B-0155    [PDF]
TI: A 3D model study of the influence of nitric acid uptake onto ice particles
AU: * von Kuhlmann, R
EM: kuhlmann@mpch-mainz.mpg.de
AF: Max-Planck-Institute for Chemistry, Department of Atmospheric Chemistry, P.O. Box 3060, Mainz, 55020 Germany
AU: Lawrence, M G
EM: lawrence@mpch-mainz.mpg.de
AF: Max-Planck-Institute for Chemistry, Department of Atmospheric Chemistry, P.O. Box 3060, Mainz, 55020 Germany
AB: The chemistry in the upper troposphere is critically dependent on the availability of NO$_x$. Lawrence and Crutzen (Tellus, 50B, 263-289, 1998) proposed that denitrification via efficient uptake of nitric acid (HNO$_3$) on ice particles and their subsequent gravitational settling could significantly perturb upper tropospheric chemistry. Despite several laboratory and field studies, the degree to which HNO$_3$ is taken up by ice or retained upon freezing of supercooled droplets is still uncertain. In this study we investigate the sensitivity of upper tropospheric chemistry to variations within the range of current uncertainties using the 3D global chemistry transport model MATCH-MPIC. Recent uptake models of HNO$_3$ on ice have been included in the model. Associated key assumption used in the general model formulation such as effective settling velocity of ice particles or ice water contents are also reevaluated in light of recent observations. The results are compared with aircraft observations of gas-phase HNO$_3$ in order to put constraints on the model assumptions. The influence of these assumptions on upper tropospheric HO$_x$ and ozone are also evaluated.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting