HR: 1340h
AN: SA43A-1101    [Abstracts]
TI: Semidiurnal tidal perturbations of temperature and horizontal wind in the midlatitude mesopause region
AU: * Yuan, T
EM: titus@lamar.colostate.edu
AU: She, C
EM: Joeshe@lamar.colostate.edu
AB: Based on lidar observation (May 2002 - Jan 2005) over full diurnal cycles, we extract semidiurnal perturbations in mesopause region monthly mean temperature, zonal and meridional winds over Fort Collins, CO (40.6N, 105W) by using least square fitting tidal-period harmonics to observational data. The results show peak semidiurnal amplitude around the winter time and minimum during the summer, which is similar to the model predictions (Global Scale Wave Model, and Hammonia-GCM). Unlike diurnal tides studied previously, more disagreement exists between observation (lidar and radar alike) and model prediction. For example, GSWM, which is a mechanistic model, underestimates semidiurnal amplitude during non-winter months, possibly because it does not account for planetary wave effect. Another significant observational amplitude enhancement near fall equinox, which may be correlated to gradients in mean zonal wind and temperature, deserves further study. We also compare with midlatitude observational results from meteor radar in Durhan, NH, and from MF radar in Platteville over the meteor altitudes (80-100 km).
DE: 3389 Tides and planetary waves
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005