Climatological modeling of horizontal winds in the mesosphere and lower thermosphere over a mid-latitude station in China

摘要

In this study, we employed the non-uniform rational B-splines surface technique to develop a provisional horizontal wind model of the mesosphere and lower thermosphere at altitudes of 87, 97, and 250 km over Kelan (38.7°N, 111.6°E) in China using Fabry-Perot interferometer (FPI) observations for the period between January 2012 and May 2014. We compared the meridional and zonal winds derived from the Kelan FPI wind model with those based on Meteor Radar wind observations at Beijing (39.92°N, 116.39°E), and those calculated from horizontal wind models, i.e., HWM93 and HWM07, at Kelan. Our analysis showed the following. (1) At 87 and 97 km, the Kelan FPI wind patterns exhibited strong annual variation in the meridional wind and semiannual variation in the zonal wind, as well as diurnal variation, which was dominated by a semidiurnal tidal variation in the meridional and zonal winds during May and September with a diurnal phase difference. The Kelan FPI wind patterns agreed well with the Meteor Radar winds and the HWM07 model results, but less well with the HWM93 model. (2) At 250 km, the FPI wind patterns agreed fairly well with the HWM93 results, where both indicated annual/diurnal variation in the meridional and zonal winds, and weak semidiurnal tidal variation. There were large discrepancies between the Kelan FPI winds and the HWM07 model results, which were mainly due to differences in the annual variation in the nighttime meridional wind. (3) The magnitude of the FPI winds was comparable to the HWM93 results but they were nearly 40-50% lower than the other winds, which is attributable to the inherent limitations of airglow measurement. Thus, this local empirical wind model could be used to investigate the climatological features of local ionospheric spatial-temporal variations.