Multiyear (2002-2011) wind observations from TIMED Doppler Interferometer (TIDI) onboard the thermosphere ionosphere mesosphere energetics and dynamics (TIMED) satellite are used for studying the typical structures and variations of mesospheric and lower thermospheric (MLT) mean zonal wind from 80 to 105 km in 120 °E meridian. Comparisons between TIDI measurements and empirical models indicate that TIDI is in good agreement with models in the extratropic regions especially in the middle and high latitudes, but significant differences occur mainly in the tropic regions. In the altitudes of TIDI's coverage from 80 to 105 km, monthly zonal winds are always westward over the tropical regions, forming an easterly band centered at the equator. Results from multiyear observations show complicated variations in the MLT tropical easterlies. The averaged width of easterlies is 37.5 degrees and corresponding variation is about 14 degrees.