  Using the horizontal neutral wind observations from the MIGHTI instrument
onboard NASA's ICON (Ionospheric Connection Explorer) spacecraft with
continuous coverage, we determine the climatology of the mean zonal and
meridional winds and the associated mean circulation at low- to middle
latitudes ($10^\circ$S-40$^{\circ}$N) for Northern Hemisphere {summer} solstice
conditions between 90 km and 200 km altitudes, specifically on 20 June 2020
solstice as well as for a one-month period from 8 June-7 July 2020 {and for
Northern winter season from 16 December 2019-31 January 2020, which spans a
47-day period, providing full local time coverage}. The data are averaged
within appropriate altitude, longitude, latitude, solar zenith angle, and local
time bins to produce mean wind distributions. The geographical distributions
and local time variations of the mean horizontal circulation are evaluated. The
instantaneous horizontal winds exhibit a significant degree of spatiotemporal
variability often exceeding $\pm 150 $ m s$^{-1}$. The daily averaged zonal
mean winds demonstrate day-to-day variability. Eastward zonal winds and
northward (winter-to-summer) meridional winds are prevalent in the lower
thermosphere, which provides indirect observational evidence of the eastward
momentum deposition by small-scale gravity waves. The mean neutral winds and
circulation exhibit smaller scale structures in the lower thermosphere (90-120
km), while they are more homogeneous in the upper thermosphere, indicating the
increasingly dissipative nature of the thermosphere. The mean wind and
circulation patterns inferred from ICON/MIGHTI measurements can be used to
constrain and validate general circulation models, as well as input for
numerical wave models.
