Search

A description of the approach is presented that allows one to control the quality of georeferencing of the MTVZA-GYa device and determine the optimal values of the correction parameters. The analysis of the data from this instrument showed that the main contribution to georeferencing errors is introduced by the roll, pitch, and yaw angles, which determine the discrepancy between the instrument coordinate system and the spacecraft coordinate system. In this regard, an iterative algorithm for selecting these angles was proposed where the difference in measurements on the ascending and descending half-turns of the MTVZA-GYa instrument was used as the minimizing function. As a result of applying this algorithm to the results of the MTVZA-GYa measurements in 2020, the mean values of the correction roll, pitch, and yaw angles of this device were calculated. The values were (–0.84 ± 0.15)° for the yaw angle, (–0.44 ± 0.14)° for the roll angle, and (+1.13 ± 0.05)° for the pitch angle. It was shown that the introduction of these angles into the MTVZA-GYa georeferencing procedure can significantly reduce its errors. Thus, the mean divergence of coastlines taken from the high-precision geographic databases and reconstructed from radiometric portraits when adjusting georeferencing is 4.5 km. [ABSTRACT FROM AUTHOR]

The procedure for geographic reference of the data of radiometric measurements of the MTVZA-GYa microwave scanner/sounder onboard the Meteor-M No. 2-2 spacecraft is described. Georeferencing is performed on the basis of the information contained in the instrument's measurement data files (in.hdf format) (the observation time of each surface element, common for all frequency channels), as well as the description of the scanning scheme of this instrument, presented in scientific periodicals (sighting angles, scanning speed, etc.). As additional information, necessary to perform the georeferencing operation (orbit parameters, etc.), data freely available on the Internet are used. The georeferencing procedure consists of several sequentially performed operations, including determination of satellite coordinates in the inertial coordinate system, forming observation vectors in the instrumental coordinate system, determining the matrices of direct and inverse transitions for the six used coordinate systems, determination of the coordinates of the observation point in the inertial coordinate system, conversion of the coordinates to the Greenwich coordinate system, etc. In the presented form, it is possible to flexibly configure this operation, taking into account the instability of the orbit spacecraft position, variations in the instrument-scanning speed, instability of setting time stamps, errors in mounting the instrument on the spacecraft, etc. Also, the described georeferencing procedure can be used as part of automated algorithms for processing measurement data and procedures for searching for optimal values of the corrective parameters (for example, the roll, pitch, and yaw angles of the spacecraft and/or instrument). [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an analysis of the experimental measurements of the azimuthal anisotropy of the microwave emissions of a rough water surface. The experimental data were obtained using microwave radiometers with operating frequencies of ~37 GHz (a wavelength of ~8 mm) on the oceanographic platform of the Black Sea Hydrophysical Experimental Facility of the Russian Academy of Sciences in the period from 2005 to 2016. This paper describes the azimuthal anisotropy effect, experimental studies, measurement methods, and data processing. A qualitative comparison of the measurement results with the model calculations and other experimental studies of anisotropy was performed. It was shown that there is a strong sensitivity of the variation in the radio emissions of a rough water surface, both to the wind speed and to its direction at different incidence observation angles. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the functional dependence of the microwave emission of a rough water surface at a frequency of 37.5 GHz (wavelength of ~8 mm). The MiROSE model (Microwave Rough Ocean Surface Emission model) is based on the experimental studies of the own thermal radio emission of the water surface, which were carried out in 2005 and 2007 on the oceanographic platform of the Black Sea Hydrophysical Experimental Facility of the Russian Academy of Sciences. This paper demonstrates the steps of the simulation for selecting the optimal functions to describe the incident angle, wind, and temperature dependences of the increment of the own water surface emission. The following parameters can be calculated on the basis of the proposed model: the increment of the brightness temperature, radio-brightness contrast, and radio-brightness temperature for horizontal and vertical polarizations of the received emission. The model is applicable to water temperatures ranging from 12.5 to 25°C, wind speeds of 3-13 m/s, and incident angles of 30°-80° measured from the nadir. [ABSTRACT FROM AUTHOR]

A correlation analysis of the model calculations and experimental measurements of wind-speed sensitivity of a rough sea-surface microwave emission at a frequency of 37.5 GHz are presented. The field data used in the research were collected over 3 years in the summer and autumn periods at the oceanographic platform of the Marine Hydrophysical Institute, Russian Academy of Sciences (RAS). A hypothesis about a significant correlation between the model calculations and experimentally measured sea-surface emission ability caused by wind forcing was formulated and tested to reveal this correlation. An evaluation of the discrepancy between the model and experimental data has been performed by an analysis of residuals. Our studies have shown that among the selected models not a single one adequately describes the experimental data. [ABSTRACT FROM AUTHOR]

Issues of the formation and recording of the spatial and angular distributions of thermal radio radiation of rainfall in the microwave range are discussed. The thermal radio-frequency radiative transfer in a threedimensional rain cell is simulated numerically with a different rainfall rate, taking into account the nonspherical shape of falling raindrops and their size distribution. The role of the three-dimensional inhomogeneity of rainfall fields in the formation of a field of their inherent thermal radio radiation in the microwave range is revealed. [ABSTRACT FROM AUTHOR]