For the first time experience was gained with the operation of Russian equipment for water content and temperature remote sensing of the lower atmosphere in the Arctic. The comparison the results of measurements by radiometric systems with data of radiosoundings in wide range of meteorological conditions had been executed. It is shown that mean difference between integral atmospheric water content, measured by water vapor radiometer WVR, and calculated from radiosoundings data does not exceed 6 % with standard deviation 0.54 kg/m2 and significant correlation coefficient 0,92. Analysis the data of meteorological temperature profiler MTR-5 allows to conclude that in general its adequately reproduce air temperature profiles in the atmospheric lower 1000 m layer. Some deviations take place only in cases of large temperature gradients. Preliminary analysis of WVR data showed that monthly mean value of integral atmospheric water content in area under study in April 2019 year practically coincides with calculated from radiosoundings, performed in 1983—1988 years at the polar station Barentsburg, nearest to the drift region, 3.61 and 3.62 kg/m2 respectively. Same time hourly mean values of integral atmospheric water content during drift varied from 2 to 10 kg/m2, with extreme values recorded between April 15 and April 20, probably due to intensive transport of air masses of the Atlantic origin. Based on MTR-5 data it was concluded that despite differences in sounding technology, the place and time of observations, the statistics of inversions registered during drift correspond well to statistics of inversions, recorded on the Arctic coastal stations and over sea ice cover of the Weddell Sea in winter.

The height of the mixing layer is a significant parameter for describing the dynamics of the planetary boundary layer (PBL), especially for air quality control and for the parametrizations in numerical modeling. The problem is that the heights of the mixing layer cannot be measured directly. The values of this parameter are depending both on the applied algorithms for calculation and on the measuring instruments which have been used by the data source. To determine the height of a layer of intense turbulent heat exchange, data were used from acoustic meteorological locator (sodar) and from a passive single-channel scanning microwave radiometer MTP-5 (MWR) to measure the temperature profile in a layer of up to 1 km. Sodar can provide information on the structure of temperature turbulence in the PBL directly. These data have been compared with the mixing layer height calculated with the Parcel method by using the MTP-5 data. For the analysis, July and September 2020 were selected in the city of Tomsk in Siberia as characteristic periods of mid-summer and the transition period to autumn. The measurement results, calculations and inter-comparisons are shown and discussed in this work. During temperature inversions in the boundary layer, it was observed that turbulent heat transfer (increased dispersion of air temperature) is covering the inversion layers and the overlying ones. Moreover, this phenomenon is not only occurring during the morning destruction of inversions, but also in the process of their formation and development.

The database presented in this study has been acquired during the SOuth west FOGs 3D (SOFOG3D) experiment for processes study. This international campaign led by Météo-France during the winter 2019-2020 aimed at deploying a unique network of both in situ and remote sensing measurements in order to document spatial and temporal variabilities of fog events. To support this scientific objective but also to conduct first data assimilation experiments within the French convective scale model AROME, an un-precedented network of 8 ground-based microwave radiometers (MWR) has been deployed in 7 different locations known to be prone to fog occurrences. The database gives access to vertical profiles of temperature and humidity (both absolute and relative) from the surface up to 10 km altitude as well as integrated water vapor and liquid water path estimates. The retrieved profiles offer a very large database that can be exploited for several scientific purposes: fog process studies at specific location, documentation on the variability of fog properties at the regional scale, better understanding of the atmospheric boundary layer (ABL) height and dynamics during wintertime conditions, development of nowcasting products dedicated to fog alerts, data assimilation experiments to improve fog forecasts, development of synergetical advanced products, and evaluation of new model configurations with advanced parameterization or resolutions. KeywordsMicrowave radiometer • Brightness temperatures • Fog • Temperature • Humidity • Liquid water path • Integrated water vapor All the authors contributed to the instrumental deployment of microwave radiometers. Pauline Martinet and Vinciane Unger conducted the scientific evaluation, data preparation, and the data delivery on the AERIS portal.