Alexey V. Kuzmin

The dependence of S-band sea surface brightness and temperature on wind vector at normal incidence

Aircraft measurements of the S-band sea surface brightness temperature at nadir as a function of wind speed and wind direction were carried out in various regions in 1985-1989. Data set of 65 circular flights was analyzed. It is shown that for water temperature recovering the wind direction is to be taken into account. >

The determination of sea surface wind and temperature with airborne radiometric data

Deals with preliminary results of the Joint US/Russia Internal Wave Remote Sensing Experiment (PreCHERI). The airborne radiometric (RM) complex and side-looking real aperture radar (RAR) are briefly described. The algorithms of sea surface temperature and surface wind restoration from RM data are outlined. The results of reconstruction are compared with true surface data. The standard deviation for wind direction is /spl Deltaspl Phi/=5.3/spl deg/(for wind speed /spl Delta/v=0.43 m/s; and for temperature /spl Delta/T=0.38 degC). The comparison of RH data with RAR pictures shows a good agreement of backscatter in VV-polarization with the value of polarizational anisotropy in RM channels. It is concluded that combined analysis of RM and RAR data enables significantly improved algorithms to be developed for ocean remote monitoring.<<ETX>>

Retrieval of gravity-capillary spectrum parameters by means of microwave radiometric techniques

The paper presents some results obtained during a series of microwave remote sensing experiments carried out on the Black Sea coast in 1999-2002. The measurements were made from a pier at the South Department of the Shirshov Institute of Oceanology with microwave radiometers operating at wavelengths of 1.5, 0.8, 0.5, and 0.3 cm. The surface wave spectrum parameters were estimated from angular radiometric measurements using a novel approach. Microwave brightness contrasts at Ka-band (37 GHz) measured over wide range of incidence angles were used for a curvature spectrum of gravity-capillary waves and a mean-square slope of gravity waves retrieval. The evolution of spectrum parameters under variable wind (ranged from 0.5-7 m/s) was investigated. The delay of brightness variation relative to wind speed as large as 1-2 h was found. The performed spectral analysis permitted to relate the observed brightness delay to short gravity-capillary surface waves, whereas longer gravity waves followed the wind practically without any delay. It is concluded that the proposed technique of gravity-capillary wave spectrum retrieval provides a useful tool for investigation of air-sea interaction and surface wave dynamics.

Air-sea interaction monitoring by remote and contact measurements: The results of the CAPMOS’05 and CAPMOS’07 experiments on an oceanographic platform in the Black Sea

The paper presents the results of the experiments CAPMOSpsila05 and CAPMOSpsila07 performed on an offshore oceanographic platform in the Black Sea. The platform equipped with contact and remote sensors is located approximately 600 m to the south of Crimea coast, Ukraine. The experiments aimed at air-sea interaction monitoring were carried out by an international research team during summer months in 2005 and 2007. Spectral parameters of wind and waves were estimated from direct and remote measurements. A comparison with known spectrum models was performed.

Azimuthal and polarization parameters of the sea-surface microwave emission measured from a pier

The paper presents the results of sea-surface microwave brightness measurements carried out from a pier in 1999 and 2000. The brightness dependence on surface wind speed was investigated over wide range of azimuth and elevation angles. It was noted that under unstable wind conditions microwave brightness contrasts correlate with wind speed. When the wind speed decreased, however, significant delay in brightness decreasing was observed. This may be treated as an evidence of cascade mechanism in the energy transfer from long waves to short gravity-capillary waves.

The Russian project "Space study of the Earth as an ecological system and human impact on this system" (Program ECOS): main goals and new remote sensing systems

The Russian ECOS program for Earth global processes monitoring is discussed. This program started with KOSMOS-1870 (1987) and ALMAZ-1 (1991) satellites and will be supported by ALMAZ-1B and ALMAZ-2 spacecrafts, by PRIRODA unit of the manned MIR orbital station, by few smaller satellites, and MIR-NASA and ALPHA programs. The largest satellites are to be equipped by multifunctional high resolution radars, microwave radiometers (radiometric complex PARC is described) and by optical and IR devices. The main goal of the project ECOS is to study the Earth as an integrated selforganizing climatic-ecological system subject to human impact. It means that all the natural media: Hydrosphere, Atmosphere, Cryosphere, Lithosphere and Biosphere are to be studied and their interactions. The results of optical, IR and microwave studies are expected to provide data for development improved prognostic models for global climatic change. Microwave remote sensing data on wind waves, water temperature, near water wind speed, evaporation rate, rains, internal waves, fronts, currents, vortices etc. are of great importance. These data may improve our representations of the global temperature change and give additional impulse to the study global bifurcation processes which may abruptly change global and/or local state of the Earth climatic-ecological system. Suggestions are presented how to integrate the Russian ECOS program with international programs like Mission to Planet Earth.

Dynamics of short waves spectrum measured by remote and contact sensors from an oceanographic platform

The paper presents the results of the experiment CAPMOSpsila05 performed on an offshore oceanographic platform in the Black Sea. Microwave radiometer measurements were applied for gravity-capillary wave spectrum retrieval using the original techniques. The spectrum components evolution under unstable wind conditions was investigated. It was demonstrated that the spectral components in the vicinity of the curvature maximum are the most sensitive to the wind velocity variations.

MULTI-ANGULAR MEASUREMENTS OF SEA-SURFACE POLARIZED MICROWAVE EMISSION CARRIED OUT DURING A SERIES OF GROUND-BASED EXPERIMENTS

The results of sea-surface microwave brightness measurements carried out from a pier in 1999-2002 are presented. The measurements were performed by W-band microwave radiometer (wavelengths of 0.3 cm), and Ka-band radiometer-polarimeter (wavelength of 0.8 cm). All equipment was installed on a pier (200 meters long) at 3 meters over the surface; the sea depth at the site was approximately 8 meters. The microwave instruments were mounted on a rotating/scanning platform, which permitted measurements at angles from 10 up to 170 degrees off nadir over 300 degrees range of azimuthal angles. The measurements were carried out 24 hours a day under various meteorological conditions. Microwave brightness dependence on surface wind was studied over wide range of incidence angles. The modulus of brightness contrasts caused by the wind was shown to increase with wind speed increasing. Also, the brightness contrast at both polarizations changes its sign as the viewing angle increases. Under variable wind conditions, the delay of brightness variation relative to wind speed as large as 1-2 hours was found. This effect may be treated as an evidence of non-linear interaction of surface waves in coastal area

Laboratory measurements of microwave emission from capillary waves

The results of polarimetric microwave measurements of thermal emission from a water surface with artificial periodic structure are presented. The goal of the experiment was a verification of the model describing the polarized microwave emission from gravity-capillary waves on a sea surface. The structure in a water tank was produced by a set of parallel nylon threads raised a little over a surface. Due to surface tension, the water surface takes a periodic profile. The measurements of the three Stokes parameters of the emission were carried out with a Ka-band polarimeter. The experimental setup allowed measurements over a wide range of view angles (from near-nadir to 70 degrees). The tank rotation allowed varying the azimuthal angle between the periodic structure and the observation plane over 300 degrees. The experimental data show the existence of the resonant peak in the Stokes parameters predicted by the model. The amplitude of the peak reached 10 kelvin. Also, drastic contrasts were registered in the azimuth dependencies of the Stokes parameters. This result is evidence of the important role that the short gravity-capillary waves play in the sea-surface polarized microwave emission.