B.G. Kutuza

Utilization of the first three Stokes parameters for the determination of precipitation characteristics

The magnitudes of the third Stokes parameter for up- and downwelling microwave emission and scattering by layers consisting of oriented nonspherical hydrometeors are estimated. In the case of downwelling radiation, incident Sun emission is also considered. It is shown that the third Stokes parameter has measurable values under certain conditions and can be utilized in addition to the first and the second Stokes vector components in order to derive microphysical parameters of the precipitation.

Passive and active Stokes vector measurements of microwave emission and scattering by precipitation

Passive and active fully polarimetric ground-based measurements of rain signatures have been carried out. The obtained results, in particular for the third Stokes parameter and the orientation angle of polarisation are compared with theoretical calculations. The principles and special features of the used radiometer and radar instruments are described.

Investigation of Sun microwave emission intensity, reflected by rough sea surface

Describes the experimental investigation of natural microwave noise signal quasi-mirror reflection at sea surface roughnesses. While the weather was cloudless, the authors used the Sun as a source of this signal. Experiments were carried in a Sun track mode, when the solar zenith angle was more than 45 degrees, and were conducted to obtain zenith section of that track. The experiments were compared to solar emission intensity data, the state of the atmosphere and wave parameters. After generalisation and normalisation these data were given in dependence of wind force and large-scale riffle waving dispersion of slopes.<<ETX>>

Dual polarisation and multifrequency measurements of rain rate and drop size distribution by ground-based radar and radiometers

Polarisation effects can be observed as well in radar as in radiometer data of stratiform and convective rain. These polarisation effects are due to different influences, e.g. the oblateness of large rain drops and path inhomogeneities. The dual polarisation technique is well known in radar meteorology. The emphasis in this contribution is therefore on the event based and statistical accuracy of the derived rain rate and on different sources of errors. In the passive remote sensing of rain the use of two polarisations is a new subject. By such measurements also drop size distributions can be derived, which improve the rain rate determination.

Estimation of rain rate by microwave radiometry and active radar during CLEOPATRA 92

Microwave radiometers operating at wavelengths 0.3, 0.8, 1.35 and 2.25 cm were used during CLEOPATRA from the ground to estimate rain rates. A model of the microwave emission of the rain layer taking into account polarization effects used for rain parameters retrieval is briefly described. Intercomparisons with simultaneous measurements with the DLR polarimetric Doppler radar POLDIRAD, distrometers and further ground based instrumentation was used for validation of the algorithm for rain rate estimations by microwave radiometry.<<ETX>>

Influence of a spatial structure of precipitates on polarization characteristics of the outgoing microwave radiation of the atmosphere

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.

Spatial inhomogeneities of rain brightness temperature and averaging effect for satellite microwave radiometer observations

The analysis of brightness temperature data, obtained by the Olympus ground station, Oberpfaffenhofen, Germany, is presented. Long time measurements with 19.2 GHz polarimetric radiometer allowed the investigation of temporal variability of atmospheric radio emission for stratiform (Nb) and cumuliform (Cb) precipitation. Conversion of temporal variations to spatial units was performed utilizing wind speed measurements. The square root of the structure function was taken as a measure for the variation intensity of brightness temperature T. Average values of T and rain rate over areas with diameters from 1 km to 15 km show significant differences.<<ETX>>

Cosmos-243 as the Starting Point for the Development of Microwave Radiometry Methods of the Earth’s Atmosphere and Surface

On September 23, 1968, the Cosmos-243 satellite was launched into orbit with four radio telescopes directed to the nadir on board. They were designed to measure the microwave radiation of the Earth’s surface and its atmosphere at wavelengths of 0.8, 1.35, 3.4, and 8.5 cm. The onboard infrared radiometer measured radiation in the band of 10–11 µm in the same solid angle as the radio telescopes. This experiment, which was initiated by scientists from the Institute of Radioengineering and Electronics (IRE) and Institute of Atmospheric Physics (IAP) and, in particular, academicians V.A. Kotel’nikov and A.M. Obukhov, broke new ground in the remote sensing of the Earth from space, which is being actively developed.

Intensity and polarization of thermal radiation of three-dimensional rain cells in the microwave band

In the present paper, the problems of formation and observation of spatial and angular distribution of thermal radiation of raining atmosphere in the millimeter wave band are addressed. Radiative transfer of microwave thermal radiation in three-dimensional dichroic medium is simulated numerically. Governing role of three dimensional cellular inhomogeneity of the precipitating atmosphere in the formation of thermal radiation field is shown.

Tropospheric water vapor structures in the clear atmosphere as observed by passive microwave and airborne LIDAR systems during CLEOPATRA 92

One objective of the field experiment CLEOPATRA, Cloud Experiment Oberpfaffenhofen and Transports, May 11-July 31, 1992, was to quantify water vapor transports from soil and vegetation to the atmosphere in dependence an precipitation events and the state of vegetation, and to improve remote sensing methods from ground, aircraft and space for observing elements of the hydrological cycle. The authors report and intercompare measurements of water vapor structures in the clear atmosphere performed simultaneously with a ground based microwave system and a DIAL system on board an aircraft. Measurements for two selected days-May 22 and June 1-showing different water vapor structures are discussed.<<ETX>>