Physical Oceanography, Vol. 18, No. 2, 2008
IMPROVED INTERPRETATION OF THE DATA OF OBSERVATIONS OF THE
BLACK SEA BY A SEAWIFS SATELLITE INSTRUMENT IN AUTUMN 1998
V. S. Suetin, S. N. Korolev, V. V. Suslin, and A. A. Kucheryavyi
By analyzing, as an example, the data of observations of the Black Sea from the space in autumn
1998, we conclude that, in some cases, the atmospheric distortions manifest themselves in all
measuring channels of SeaWiFS instruments and lead to significant errors in determining the
concentration of chlorophyll according to the standard NASA algorithm. After additional rejec-
tion of the data with negative values of the spectral brightness of the sea surface at a wavelength
the results of evaluation the concentration of chlorophyll are in good agreement with
the available data of direct measurements. We also present a detailed discussion of some specific
features of operation of the NASA algorithm of atmospheric correction playing an important role
in the interpretation of the data of observations of the Black Sea.
Optical instruments of the same type as
(Sea-Viewing Wide Field-of-View Sensor) operating in
the space enable us to accumulate vast data arrays of global observations used to compute (with the help of spe-
cial algorithms) the concentration of chlorophyll in the ocean and the values of the optical parameters of water
and atmosphere and to determine the variability of these parameters on different space and time scales. At the
same time, the application of these data require certain precautions because, in numerous cases, the accumulated
results contain significant errors due to the presence of atmospheric distortions (that can hardly be taken into ac-
count) and the complex multifactor character of variations of the optical properties of seawater [1–7]. As a typi-
cal example, we can mention an evident contradiction between the data of satellite observations of the abyssal
part of the Black Sea in autumn 1998 described in  and the data of direct measurements of the concentration
of chlorophyll a presented in . These discrepancies become especially important in the case of investigation
of long-term processes covering large areas of the sea.
The aim of the present work is to study the possibility of detection and rejection of the erroneous data of
satellite observations according to formal criteria with regard for the specific causes of the appearance of distor-
tions. In addition, it is also of interest to supplement the estimates of the behavior of the optical parameters of
water in summer 1998 obtained in  by the reliable data for the autumn season.
To a significant extent, the operation of the SeaWiFS instruments in the space is experimental. Hence,
various elements of the system of data processing (from specifying the calibrating parameters and the choice of
the set of computed quantities to various details of the algorithms of processing of the data of satellite measure-
ments) are subjected to numerous modifications and improvements.
The principal results of the present work were obtained by using the standard products of processing of the
so-called second level (Level-2 format) prepared in the course of complete reprocessing of these data in the sec-
ond half of 2005 and stored in the NASA archive.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
68–79, March–April, 2008. Original article submitted November 3, 2006.
106 0928-5105/08/1802–0106 © 2008 Springer Science+Business Media, Inc.