HR: 08:40h
AN: SA41A-03    [PDF]
TI: The EEA method of chemical lifetime calculation and its application to the sodium layer
AU: * Xu, J
EM: xurrjy@center.cssar.ac.cn
AF: Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, 100080 China
AU: Smith, A K
EM: aksmith@ucar.edu
AF: Atmospheric Chemistry Division, NCAR PO Box 3000, Boulder, CO 80307 United States
AB: The method of the eigenvalue and eigenvector analysis (EEA) to determine the response of a chemical system to perturbations is introduced. We apply the EEA method to analysis of the mesospheric sodium layer. The results show that the lifetime determined using EEA is more than a day in the vicinity of the peak of sodium layer while the traditionally defined chemical lifetime for sodium is only a few minutes. In the region near the peak of the sodium layer, the timescale for gravity wave transport is substantially shorter than the chemical lifetime, indicating that the Na layer acts as a tracer of dynamical perturbations on short time scales (a day or less). At the bottom side of the sodium layer, photochemistry is rapid compared to transport or diffusion. Tests of the sensitivity of the EEA chemical lifetime of Na show that it is sensitivity to changes in the densities of background chemical species such as O3, H, and O, but that the transport timescale is shorter than the chemical timescale for realistic values. These results provide a theoretical basis for using Lidar observations of sodium to infer gravity wave vertical velocities.
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting