A review of mesospheric and lower thermosphere wind models

The existing empirical mesosphere/lower thermosphere (MLT)wind models, in particular CIRA-86 (Fleming et al.), HWM (Hedin et al.) and GEWM (Portnyagin et al.) models, are compared. The main reasons of the differences between the models are discussed. One of the most important reason is connected with the differences between the used ground- and space-based datasets. An analysis of the role of year-to-year wind variations and the longitudinal prevailing wind variability, as well as the effects of non- migrating tides in construction of the empirical models is presented. The problems of the systematic biases between the different ground-based and space-based measurement techniques are also discussed. Some comparison of the empirical models and the numerical models is also made. The recommendations for constructing of the updated new CIRA wind model for the MLT region have been done.