A Guide to the Russian Academy of Sciences - University of Texas ...

field in ocean surface; d) monitoring of ocean surface states using optical and
microwave airspace data sets.
The focus of our investigation (1975-1995, see "Publication List") has been analysis of
multiphase ocean surface structures including foam, whitecaps, spray, underwater
bubble populations, oil emulsions, young ice. For example the effects of high
microwave emission of foam and whitecaps are due to specific absorption and
scattering properties of bubbles.
Important issue is spray and underwater bubbles. It was shown that effects due to spray
can yield both positive and negative brightness temperature contrasts. The
spectrum of microwave radiation at mm- and cm- ranges depends on droplets' size
distribution and "optical" thickness of spray clouds. At the same time emissivity
variations due to underwater air bubbles are significant at long-microwave ranges
of radiation which is connected with the sharp change of skin-layer depth.
Another problem is a global distribution of wave breaking field at the storm conditions.
This investigations are made by means of airspace photography and optical image
processing. In particular we have found that size histograms and fractal dimensions
differ for foam streaks and whitecaps and vary depending on wind wave
generation state and fetch. The idea of fractal dimension has resolved the problem
of ocean surface state quantization using remote sensing techniques.
On the basis of optical and microwave investigations a composite microwave model of
ocean-atmosphere system is designed. This model take into account not only the
structural hierarchy of natural multiphase media in air-water interface but also the
dynamic characteristics of ocean boundary layer and statistics of foam coverage
and whitecaps. Some dynamic weight coefficients as area fractions of different
types of interface factors (foam formations, spray, underwater bubbles, large- and
small-scale wind waves, turbulence roughness and other) are introduced in the
composite model. Multifrequency microwave radiometric complex at 1,4-- 37
GHz and airspace optical devises with a high spatial resolution could be used. Also
side-looking radar (SLAR) or synthetic aperture radar (SAR) would be desirable
for identification of the ocean-atmospheric stratifications including internal waves.
The concept of combined optical microwave technique based on physical background will
be applied to further investigations which are supposed to be carried out according
to the research proposal. The main scientific problem is the determination of local
and spatial nonuniform ocean surface characteristics by means of microwave, radar
and optical remote sensing techniques.
Dr. Victor Raizer
Space Research Institute of the Russian Academy of Sciences
Post Address: Profsoiusnaia, 84/32
117810, Moscow, Russia
E-mail: vraizer@esoc1.iki.rssi.ru
Fax: 7-095-333-3177
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28. Applied Astronomy Institute (IAA) in St. Petersburg
188