A review of mesospheric and lower thermosphere models

The empirical mesosphere/lower thermosphere (MLT) models, in particular Fleming et al. [Fleming, E.L., Chandra, S., Schoeberl, M.R., Barnett, J.J. Monthly mean global climatology of temperature, wind, geopotential height and pressure for 0-120 km. NASA Technical Memorandum 100697, 1988; Fleming, E.L., Chandra, S., Barnett, J.J., Corney, M. Zonal mean temperature, pressure, zonal wind and geopotential height as function of latitude. Adv. Space Res., 10 (12), 11-59, 1990.], HWM-93 [Hedin, A.E., Fleming, E.L., Manson, A.H., Schmidlin, F.J., Avery, S.K., Clark, R.R., Franke, S.J., Fraser, G.J., Tsuda, T., Vial, F., Vincent, R.A. Empirical wind model for the middle and lower atmosphere. J. Atmos.Terr. Phys., 58, 1421-1447, 1996] and GEWM [Portnyagin, Yu.I, Solovjova, T., Merzlyakov, E., et al., Mesosphere/lower thermosphere prevailing wind model. Adv. Space Res., 34, 1755-1762, 2004] models, are compared. The main reasons of the differences between the models are discussed. These reasons are mainly connected with the differences between the used ground- and space-based datasets, including the systematic biases between the ground-based and space-based measurements, and with the different methods of the data assimilation. The effects 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 climatic empirical models is not so strong. The recommendation to construct a new and updated CIRA wind model for the MLT region has been followed.