Non-migrating diurnal tides as measured by the TIMED Doppler interferometer: Preliminary results

Abstract

Preliminary meridional wind data from the TIMED Doppler Interferometer (TIDI) onboard the TIMED satellite are analyzed for nonmigrating diurnal tides. Tidal definitions are given for the most pronounced westward, eastward and standing oscillations (w2, e3, s0). The analysis interval is March 2002 to June 2004 and covers the altitude range 85-105 km. Monthly tidal wind fields from 40 � S-40 � N are presented. TIDI tides compare favorably with previously reported 95 km HRDI results. Nonmigrating diurnal tidal wind speeds larger than 30 m/s are observed thus emphasizing the important role of nonmigrating tides in middle atmosphere coupling. A comparative analysis with the Global Scale Wave Model (GSWM) and the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) indicates that both latent heat release in the tropical troposphere and non-linear Planetary Wave / migrating tide interaction are important sources of nonmigrating tides in the mesosphere and lower thermosphere.