Plausible explanation for the equatorial temperature and wind anomaly (ETWA) based on chemical and dynamical processes

Abstract

It has been proposed earlier through independent studies that either 'chemical heating' or 'ion drag' might be responsible for the generation of a large-scale low-latitude process, namely the Equatorial Temperature and Wind Anomaly (ETWA). The present study based on simultaneous measurements of ionospheric and thermospheric parameters by DE-2 satellite alongwith some of the standard models shows that both the processes are important and necessary for the generation of ETWA. A proper quantification has been attempted with reasonable success by taking into account both the chemical heating and ion drag. The chemical heating which operates irrespective of the time of the day, has been shown to account for 25-30 K (˜30%) of the neutral temperature enhancements in ETWA. On the other hand, the ion-drag associated heating, which is operative only during daytime conditions could raise the temperature by 60-80 K. Thus the relative importance of ion drag and chemical heating have been evaluated in arriving as a plausible explanation of ETWA.