By using a general circulation model, behaviors of the eastward propagating diurnal tide with zonal wavenumber 3 (DE3) and their relation with the convective activity in the tropical troposphere are examined. The amplitude of the DE3 is significant in the equatorial mesosphere and lower thermosphere (MLT). Day-to-day variations of the DE3 amplitude are evident in the MLT region, and are closely related with temporal variations of the rainfall rate in the tropics. Estimates of the EP flux divergence due to the DE3 indicate that this convective modulated DE3 activity induces day-to-day variations of the wave-induced driving of the zonal mean zonal wind in the MLT region. Our results show that temporal variations of the zonal mean zonal wind in the equatorial MLT region are influenced by the moist convective activity in the tropics.