Physical Oceanography, Vol. 15, No. 2, 2005
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING
HYDROPHYSICAL FIELDS IN THE OCEAN
DETERMINATION OF MESOSCALE SURFACE CURRENTS IN
SHALLOW-WATER REGIONS ACCORDING TO THE DATA
OF HIGH-FREQUENCY RADAR MEASUREMENTS
L. M. Ivanov and O. V. Mel’nichenko
We propose a new method for the evaluation of the velocities of surface currents according to the
data of measurements carried out by using high-frequency land-based radars. The method is
based on the representation of the velocity fields via two scalar potentials, expansion of these po-
tentials in series in basis functions, and determination of the coefficients of expansion according
to the data of radar measurements as solutions of the corresponding variational problems. The
errors of the procedure of determination of the coefficients of expansion are removed by using a
special regularization procedure based on information theory. The proposed method enables one
to fill gaps in the space and time series of radar measurements. We illustrate the method by an
example of numerical analysis of mesoscale and submesoscale
surface currents in
the Monterey Bay (California, USA) performed on the basis of the data of radar measurements
carried out in August 1994.
Surface currents with characteristic scales from several hundred meters to several kilometers play an impor-
tant role in the exchange of momentum, heat, oxygen, etc. between the atmosphere and the ocean in the shelf
zones. The knowledge of the structure of these currents is important for the analysis of the distribution of zoo-
and phytoplankton in coastal water areas, prediction of the behavior of oil spots, and propagation of other sur-
face-active substances .
Rapidly variable coastal currents can appear as a result of superposition of several types of circulations and
can be generated by various dynamical factors. Hence, correct estimations of the space and time variability of
currents of this type are possible only on the basis of long-term observations of their characteristics, which, in
general, can be realized by the methods of remote sensing of the sea surface. At present, one of the most pro-
mising techniques in this field is connected with the application of special high-frequency (HF) radars .
The concept of application of HF radio pulses (with carrier frequencies of ∼
MHz) for the remote
sensing of the sea surface is developed for several decades beginning from the pioneer work , where the effect
of resonance reflection of radiowaves from short surface gravitational waves of certain wavelengths was discov-
ered for the first time. This effect is used as basic in the procedure of recording currents by HF radars and allows
one to perform remote measurements practically continuously (with intervals of
in very large coastal wa-
(up to 2500
and with high spatial resolution
km). The reader can find detailed informa-
tion concerning the physical principles and methods of application of HF radars for measuring surface currents in
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
24–36, March–April, 2005. Original article submitted November 18,
2003; revision submitted January 12, 2004.
92 0928-5105/05/1502–0092 © 2005 Plenum Publishing Corporation