The possibility of assessing the avalanche hazard in the North Caucasus mountains with the use of the data of modern Era-Interim, SCSR, and NCEP-NCAR reanalyses is considered. The data have been previously compared with the materials of weather stations (average seasonal values of the surface temperature and precipitation). The avalanche hazard was estimated with the use of a correlation matrix, which is based on a relationship between the avalanche hazard characteristic and the standard deviations of the seasonal values of temperature and precipitation. The synoptic processes that increase the probability of catastrophic avalanches were identified. The anomalously high avalanche hazard was shown to form at a negative anomaly of air temperature at land surface and in higher air layers at an integral moisture content of the atmosphere close to the norm.

Experimental field campaigns are an essential part of atmospheric research, as well as of university education in the field of atmospheric physics and meteorology. Experimental field observations are needed to improve the understanding of the surface-atmosphere interaction and atmospheric boundary layer (ABL) physics and develop corresponding model parameterizations. Information on the ABL wind profiles is essential for the interpretation of other observations. However, wind profile measurements above the surface layer remain challenging and expensive, especially for the field campaigns performed in remote places and harsh conditions. In this study, we consider the experience of using two low-cost methods for the wind profiling, which may be easily applied in the field studies with modest demands on logistical opportunities, available infrastructure, and budget. The first one is a classical and well-known method of pilot balloon sounding, i.e., when balloon is treated as a Lagrangian particle and tracked by theodolite observations of angular coordinates. Second one is based on a vertical sounding with a popular and relatively cheap mass-market quadcopter DJI Phantom 4 Pro and utilizes its built-in opportunity to restore the wind vector from quadcopter tilt angles. Both methods demonstrated reasonable agreement and applicability even in harsh weather conditions and complex terrain. Advantages and shortcomings of these methods, as well as practical recommendations for their use are discussed. For the drone-based wind estimation, the importance of calibration by comparison to high-quality wind observations is shown.

Skin temperature (Ts) plays a central role in shaping the land surface energy balance and is also widely available from remote sensing for model evaluation and data assimilation. Both offline land models and land–atmosphere coupled models still have difficulty in realistically simulating or predicting Ts. In the case of an inhomogeneous surface, under the same atmospheric conditions, there are patches of different skin temperature and different daily variability. This observational study reports variations of surface fluxes (turbulent, radiative, and soil heat) and ancillary atmospheric/surface/soil data based on in-situ measurements conducted at Mukhrino field station located in the middle taiga zone of the West Siberian Lowland. To measure the surface temperature, we used an infrared camera (TIR, ~8–14 mkm wavelength range) based on an unmanned aerial vehicle. This UAV-based system provides high-resolution multi-sensors data acquisition. It also provides maximal flexibility for data collection at low cost with minimal atmospheric influence, minimal site disturbance, flexibility in measurement planning, and ease of access to study sites (e.g., peatlands) in contrast with traditional data collection methods. e demonstrate that the temperature of the boggy surface has significant variability: depending on the time of day, temperature contrasts can reach more than 10 degrees, which is associated with different surface moisture and albedo. A technique has been developed for restoring the surface albedo from the data of IR measurements. Ground measurements have shown that the variations of temperature and humidity across the subsurface layer can be very large. Furthermore, these variations are directly related to the concept of a difference between the roughness length for momentum versus that for heat. Information about the ratio of z0/z0h is necessary in order to be able to use surface skin temperature from satellite remote sensing for the computation of surface fluxes. The relationship between the difference in skin temperature and soil contact temperature with the heat balance, especially with sensible heat fluxes and heat flux through the soil, is considered. The parametrizations obtained in this work can be used in Earth System models to represent wetland ecosystems. The work was supported by RFBR grant 18-05-60126, by the Moscow Center for Fundamental and Applied Mathematics and within the grant of the Tyumen region Government in accordance with the Program of the World-Class West Siberian Interregional Scientific and Educational Center (National Project "Nauka").

The possibility of using the data of modern ERA-Interim, CFSR and NCEP-NCAR re-analyses to assess an avalanche danger in the mountains of the North Caucasus is considered. Previously, the mean seasonal values of the surface air temperature and seasonal precipitation amounts obtained from the reanalysis archives were compared with the data of meteorological stations. The mean temperature of the cold period (November-March) was best reproduced by the ERA-Interim reanalysis: the correlation coefficients amounted to 0.8-0.9, and the average deviation from the station data +/- 1.7 degrees C. The accuracy of measurements of precipitation is lower, but the magnitude of the errors does not exceed the limits of inter-seasonal variability. To estimate the avalanche hazard, a correlation matrix was used based on the relationship of the avalanche hazard indicator with the standard deviations of seasonal values of temperature and precipitation. The ERA-Interim reanalysis reproduces the avalanche danger in the North Caucasus most adequately (71% of coincidences with the actually observed events). Synoptic processes which may promote formation of catastrophic avalanches in the North Caucasus were also determined. The most typical situation is the position of a high-level cyclone over the Eastern Europe, accompanied by the invasion of cold air masses from Scandinavia that activates cyclogenesis in the Mediterranean. It was found that the extreme avalanche hazards occurred at negative anomalies of mean seasonal air temperature near the ground and in the middle troposphere (about 1.5-2 degrees C) when the integral water content of the atmosphere was close to the norm.

This work is devoted to assessing the use of reanalysis data for diagnosing the danger of avalanches using the Caucasus Mountains as an example. This method is applicable to entire mountain regions, not individual slopes, and uses the results of both observations and numerical modeling in the atmosphere. A comparison of observational and reanalysis data of Era-Interim, CFSR, and NCEP-NCAR is performed based on a classification of winters by using air temperature and precipitation data to assess avalanche hazard. The accuracy of the temperature and precipitation data and their influence on avalanche hazard are analyzed.

The article is devoted to various aspects of the use of unmanned aerial vehicles (UAV) for the study of the atmospheric boundary layer. The characteristics of the atmospheric boundary layer, measured using the UAV, are considered. The types of devices and measuring systems used are presented. The characteristics of measuring systems installed on a fixed-wing aircraft and copter UAVs developed in the A.M. Obukhov Institute of Atmospheric Physics RAS (IAP RAS) are presented. A brief overview of a number of the IAP RAS measurement campaigns is given. The prospects of using UAV in meteorology and atmospheric physics are considered