Space data research center all-union research institute of marine fisheries and oceanography (VNIRO) ussr ministry of fisheries

Aeta Astro,autica Vol. 22, pp. 339-345, 1990 Printed in Great Britain

0094-5765/90 $3.00+ 0.0 Pergamon Press pie

SPACE DATA RESEARCH CENTER ALL-UNION RESEARCH INSTITUTE OF MARINE FISHERIES AND 0 C E A N 0 ~ R A m Y

(v~n~o)

USSR MINISTRY OF FISHERIES

CURRENT STATUS AND FUTURE OF SPACE DATA APPLICATION IN FISHERY OCEANOGRAPHY Vanyushin G.P., Zonov Yu.V., Potalohuk S.I. Abstract

The scale of operations carried out • by the USSR Ministry of Fisheries' fishing fleet requires a sound scientific basis. Such a basis is provided by "fishery oceanography" - a branch of science that studies the environmental factors which exert influence on fishing conditions. Remote sensing satellites are a new s o u r c e o f d a t a on o c e a n i c c o n d i t i o n s

for fishery oceanography. The USSR Ministry of Fisheries is deve loping space data service for its own needs. At present the main output of the Service are sea surface temperature maps Which are distributed between the Ministry' users. Other types of information LTe.~esulta of iJattrJ~6~atiem efvldeb

Im~fex7 in different spectral regions. Joint anal~sis cf all the available data is employed by fishery oceanographers for managing search and fishing fleet operations. Im I988 the USSR Ministry cf Fisheries vessels fished cut about II.3 million t of marine products providing 20~ cf animal p r c t e i n s consumed i n t h e c o u n t r y . Effective work o f the fishing fleet is based on operations of scientific and search vessels which carry out studies of the ocean and its biological productivity together with searching for fish shoals. This monitoring fleet consists cf about I20 units and their maitenance costs the Ministry about I00 million roubles p e r year. Collected scientific data and information sn marine environment together with biological informationon the stocks, behavicur and conditions cf fish and other marine organisms are distributed among specialists and form the basis of the scientific discipline - "fishery oceanography". Fishery oceanography can be defined as a branch of science that studies the influence of natural abictic and biotic f a c t o r s cn t h e r e p r o d u c t i o n of commerc i a l fish species, distribution and behaviour of shoals and conditions cf effective fishing operations, The main tasks of fishery oceanography stem from practical needs of the fishing fleet to know the envircnmental conditions during search and fishing operations. The speoles which are of interest to the USSR Ministry of Fisheries are distributed in the Wcrld Ocean over an area cf more than 200 million square ESAometers. Regular mcnitoring of such a vast

area even with a large number of available search ships - 120 vessels - cannot completely satisfy the requirements in t h e i n f o r m a t i o n Which a r e a d v a n c e d by t h e specialists in fishery o c e a n o g r a p h y . F o r

this reason any possibility in increasing the amount cf obtained information is widely greeted by them. Over the last decades remote sensing satellites have become a new source of unique data on sea surface state conditions. The main features of satellite data of primary importance to the fishery oceanographers are the possibility to observe "at one glance" large o c e a n i c areas which

are measured in millions cf s q ~ e kilometers, high speed cf data delivery, the integrating effect cf such observations that permits to detect large low contrast objects. The presently used satellite remote sensing instruments make it possible tc determine primarily sea surface temperature, its color and surface roughness. Research work in methods of using all these types c f information for fishery oceanography purposes is carried cut at the Ministry's scientific institutions but regular provision of the users with space-based infcrmation is maimtained only for sea surface temperature (SST) maps. This is due to the fact that regular cbservations of sea surface withla the spectral, spatial and time requirements of fishery oceanography are currently perfcrmed only by the USSR and USA met ecrological satellites. Spaelal and time requirements cf various users cf the USSR Ministry of Fisheries differ to a large extent - from direct data reception to monthly averaging, from neighbouring local areas of hu.~dreds of miles to regions of thousands of miles in diameter. Current technical level of operational satellite systems can satisfy only in part the set cf these requireme~s. Fcr this reason nct all the users are completely satisfied by the infcrmation that is put out by the Space Dat@ Sex,rice of the fishing industry ~Flg. I). In the first place direct transmission of satellite data meets the requirements of fishing vessels' captains on sea cond i t i o n s concerning the adjacent areas to the boat. This is rather ccmplicated t o achieve with the existing optical observation systems in the IR-speotrum due to cloudiness in the regions of the World 339

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Ocean where active fishing takes place. The biggest interest towards space da~ ta is expressed by fishery oceanographers who prepare forecasts of fishery conditions for various time periods. Fishery region managers and scientific and search vessels' captains are also interested in this information in order to know the hydrological situation in their region and dynamics of its o h a n g~I.

At the present time IR SST-maps are issued mainly by the Head organization of the Space Data Service - The Main Research Space Data Center of the fishing industry (Glavcenter "Ooean") in Moscow at the All-Union Research Institute of Marine Fisheries and 0oeanog~aphy (VNIR0). The main flow of space IR data originates at the USSR Hydrometeorological Center on computer compatible tapes oarryIng data from the Soviet meteorological satellites "Meteor-2". The forma of the imagery is a 38 x 38 matrix of radiation temperatures of the underlying sturfaoe. The process of compiling SST maps consists of two stages. The first one is the compilation of so called sea surface temperature structure (SSTS) maps. The second one is the compilation of SST maps themselves. The basic idea of SSTS maps oompila@ tion is the selection of maximum values of underlying surface radiation temperatures which have the largest probability to correspond to SST if we assume the well known fact of sufficiently lower radiation temperatures of any cloud formations which occur in a surveyed pixel. Maximum value selection is performed in two stages. At the first one the 38 x 38 matrix is divided into smaller squares, mainly 5 x 5 values (except at the sides where the elements are 5 x 4 values). For each new element one maximum value is selected and the whole scene is transferred into a 8 x 8 form. At this stage spaclal filtration is achieved during which the probability of observation by a satellite sensor of unspoiled by clouds SST is increased. The next step is an application of a time filter which consists in selecting a maximum value for each of the 8 x 8 matrix elements from a time series of such matrices obtained during a definite time period. From meteorology it is known that the mean value of a natural synoptic period which consists of two antipodal cycles of atmospheric processes amounts to I012 days. For this reason the selection of the time period at present is 15 days. Precise knowledge of the time of cloud passing over the aquatoria being analysed makes it possible to shorten the 15-day maximum selection period. The relatively big selection period now accepted by us is due to small amount of IR data on the sea surface that is collected through the gap~ between clouds

during one pass o f the "Meteor-2" satellite over the region of observation. Both stages of cloud filtration - spaolal and temporal - are carried out with the aid of computers and an oceanographer receives a numerio~l map on which he plots isotherms with a I~ interval introducing corrections due to the speoifloity of the region which he as a specialist takes into a c c o u n t . At the last stage sea surface temperature measurements made by the ships in the region at the time are used to introduce corrections into the SSTS maps. Thus e pToduoe the sea surface temperature SS~) maps with absolute values of water temperatures. Examples of such maps are shown in Figs. 2 and 6. Verification o f these maps is done by comparison with the following material: quazis~nhronous ship measurements of temperatures in the region; - synhronous observation data of the region obtained bx the satellite data receiving stations [IR-ima. gery from NOAA and Meteor-2 satellites); - SST maps produced b~ other satellite data processing centers [USA, Canadap Japan). There are a number of examples of effective use of satellite SST maps for solving fishery oceanography problems. For example / in December 1986 an analysis of the relatively prolonged presence of anomously low values of the Southern oscillation index pointed to the possibility of development of a medium-scale EINiEo phenomenon with a maximum being achieved in April-June 1987. Following analysis of space SST maps confirmed the predicted EI-NiEo development (Figs. 2a, 2b, 20, 2d). Comparison of the SST maps for corresponding time periods o f Janucrry 1986 and 1987 showed that between 80~W and Peru Coast the isotherms are shifted to the east relative to^the previous yea~. For i~stanoe, the 2 ~ C isotherm was 2~ and 23~C isotherm 3 v in longitude closer to the South America continent. The upwelling well pronounced on January 1986 SST maps seems to be sufficiently weaker in 1987. In 1986 the 21~C isotherm that followed th~ P e r u v i ~ shore line was between t~e 5 ~ and 15 S, in 1987 it was the 23 C isotherm. For the region north of the 30°S the isotherm configuration was different from the previous year. In 1986 the isotherms went longitudewise that is typical for the region but in 1987 they changed to a more latitudinal direction. This is probably due to a weakening of the climatic upwelling and currents flowing northwards. On the February and March maps (Figs. 20, 2d) one can see the gradual spread to the south of warm surface ~aters. I~ January slightly south of IOnS the 25~C isotherm was located (Fig. 2b), ~uFebruary its place was taken by the 27~C ~sotherm
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therm (Fig. 2d). especially in the absence of ship data The differences observed on the SST for the region. These ohamts are also maps between the hydrological conditions usefull in oases when there is a need to in 1986 and 1987, namely - distribution determine or monitor the development or to the south of anomalously warm surface continuation of upwelling activity near waters near the Peruvian shore, practithe shore. In 1988 ~0 such charts were cally complete absence of the upwelling compiled for the southeastern part of and latitudinal distribution of the isothe Pacific Ocean (Fig. 9). therms - provided a means for making a Evaluation of fishing conditions and conclusion that active development of EItheir dynamics, formulation of recommenNiEo would take place in the early 1987. dations for the fishing fleet and search SST maps are issued by Glavoenter vessels is achieved by Joint analysis of "Ocean" on a weekly basis for 8 regions SST maps, map schemes of phytopiankton of the World Ocean covering 40 million fields~ gradient zone location and hydrosquare kilometers. Fig 3 shows the localogical data coming from search vessels. tion of these regions in the World Ocean. Zones favourable for fish shb&l~concenThese maps are distributed to fishery tration are thus determined. The video oceanography specialists in various scienimage (Fig. ~), SS~ map (Fig. 6)~ map tific and fishing operations managing descheme (Fig. 5) and an IR image ~Fig. 7) partments of the industry. They are also sent via radio links to regional fishing obtained N~vember 28, 1987 from a NOAA fleet operation chiefs staying on board satellite can present a sample of an inthe ships in that region. formation package used for the Joint ana355 such maps were issued and distrilysis of situations in a fishing region. buted in 1988. Joint analysis of all types of inforIn addition to the E - d a t a used for mation for a fishing region is made on the SST map compilation video imagery in board the main regional search vessel the 0.5-0.6 M m spectral interval [Fig. which receives all the information from 4) is used f6r visual analysis and deterGlavoenter "Ocean" and from other vessels mination of phytoplankton fields, cycloequipped with meteorological satellite data receiving stations. On the basis of nic and anticyclonic vortices, gradient this analysis recommendations regarding zone locations. Differentiation between search and control fishing operations in atmospheric and hydrobiologioal objects perspective regions are planned. is carried out by comparison of their Space Data Service also produces other diff~rentoP%~Oal~den|lttes~ii %h~ 0;8-' materials. For instance, for some regions ¢.I ~ m a n d 0.5-0.6 ~ m spectral regions. of the World Ocean and seasons of the These data are obtained by ~ U - M and MSUyear special ice condition maps are preS~ multispectral scanning systems carried pared, as for the Antarctic Region [Fig. out by the I766, I869 and I989 "Cosmos" 8) and the Sea of Okhotsk. In the Latter series and "Ocean" satellites. case the maps are prepared in the Pacific On the basis of visual analysis map Research Institute of ~,~rine Fisheries schemes (Fig. 5) of phytoplankton field and Oceanography where there is another distribution and gradient zone location product of thematic space data processing are prepared. Elements of hydrobiologibeing issued, i.e. maps of frontal zones cal characteristics of the region obserof the Far East Region. ved during visual analysis of optical The fishery oceanography specialists gradients in the 0.5-0.6 spectral imageexpress a constantly growing interest tory are also marked. Other information wards receiving space-based information such as fishing fleet location is also even of it~ present rather low quality. placed on the map scheme if required. This points to a promising future of spaSatellite data in the visual spectral ce-based methods of ocean observations region are also used for compiling charts from satellites. ~ e future development of meteorological situati~ms for the reof these methods should be concentrated gions of fishing fleet operations (Fig.9). not only on the development of new more Cyclone trajectories and speed of their effective sensor systems but also on betmovement and location of boundaries withter data processing and interpretation in the tropical convergence zone are plotmethods and information dissemination systed. tems to serve the end user. Location of bario centers and wind speeds in a region are used by oceanographers in Glavcenter "Ocean" for inReferences creasing reliability of analysis of the IR satellite data in the process of making ~Kuznetsov A.~7., ~roshkov i.:L., Greohina SST maps for the fishing regions. A.~. ~l-Nino I986-I987. CPPS, ~oletin These meteorological charts are used ~ F E ~ T~o 2~, 1988, Bogota, p.p. ~0-~5° for the correction analysis of the SST maps. Knowledge of Center location of bario formations and wind speed situation is needed for monitoring the changing the isotherm field in a sequence of SST maps,

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