This study shows that the mesospheric winds are affected by an expansion–shrinking of the mesosphere and lower thermosphere that takes place due to changes in the intensity of the solar radiation, which affects the density within the atmosphere. On seasonal timescales, an increase in the neutral density occurs together with a decrease in the eastward-directed zonal wind. Further, even after removing the seasonal and the 11-year solar cycle variations, we show a connection between them.

A comparison between the GNSS tomography technique and WRFDA in retrieving wet refractivity (WR) is conducted in HK during a wet period and a dry period. The results show that both of them can retrieve good WR. In most of the cases, the WRFDA output outperforms the tomographic WR, but the tomographic WR is better than the WRFDA output in the lower troposphere in the dry period. By assimilating better tomographic WR in the lower troposphere into the WRFDA, we slightly improve the retrieved WR.

We use data from two NASA satellites and a general circulation model of the upper atmosphere to elucidate the key factors governing the abundance and diurnal variation of nitric oxide (NO) at near-solar minimum conditions and low latitudes. This has been difficult to do previously, because NO data are typically taken from satellites in sun-synchronous orbits, meaning that they only acquire data in fixed local times. We overcome this limitation through model simulations of the NO diurnal cycle.

Data from two instruments (MODIS and MISR) on board the Terra satellite were compared with seven AERONET ground-based stations located in the Middle East and North Africa. The goal was to test which space-borne instrument can better represent ground data over different geographic locations. Comparing satellites’ retrievals with corresponding AERONET measurements shows that space-borne data retrieval accuracy can be affected by landscape and topology.

Based on hourly averages of the total electron content (TEC), a regional model of the TEC was constructed. Annual averages calculated from monthly medians of the detrended TEC were used to estimate any trends in the TEC over the African low latitudes. A predominantly negative trend in the ionospheric TEC was observed in the vicinity of the dip equator.

Spatial extrapolation of an ionosphere TEC map was carried out using a SVM learning algorithm. There has been much research on the temporal extrapolation or prediction of TEC time series, but the spatial extrapolation has rarely been attempted. Some researchers have performed simultaneous extrapolation both in time and in spatial domains, but this research covers the spatial extrapolation only by using an inner TEC map. This spatial TEC extrapolation can be useful for small countries.

In this paper, we propose an improved pixel-based water vapor tomography model, which uses layered optimal polynomial functions by adaptive training for water vapor retrieval. Under different scenarios, tomography results show that the new model outperforms the traditional one by reducing the root-mean-square error (RMSE), and this improvement is more pronounced, at 5.88 % in voxels without the penetration of GNSS rays. The improved model also has advantages in more convenient expression.

In the present work we used unique data on the magnetic field in the Jovian magnetosphere measured by the Juno spacecraft. The data allowed us to determine optimal parameters of the magnetodisc in the paraboloid magnetospheric model and find the ways to qualitatively improve the model.

Comparing Swarm GPS-only gravity fields to the ultra-precise GRACE K-Band gravity field schematic errors occurs around the geomagnetic equator. Due to the end of the GRACE mission, and the gap to the GRACE-FO mission, only Swarm can provide a continuous time series of gravity fields. We present different and assess different approaches to remove the schematic errors and thus improve the quality of the Swarm gravity fields.