Indian Journal of Marine Sciences


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ISSN: 0379-5136                                                                                    CODEN: IJMNBF

VOLUME  34

NUMBER  4

DECEMBER  2005

CONTENTS

Special Issue On: Ocean Colour Remote Sensing

 

Papers

 

Remote sensing of ocean colour: Towards algorithms for retrieval of pigment composition

  *Shubha Sathyendranath, Venetia Stuart, Trevor Platt, Heather Bouman,Osvaldo Ulloa & Heidi Maass

333-340

 

 

Comparison of in situ and remotely-sensed chlorophyll-a in the Northwest Atlantic

 *Cesar Fuentes-Yaco, Emmaneul Devred, Shubha Sathyendranath, Trevor Platt, Linda Payzant, Carla Caverhill, Cathy Porter, Heidi Maass & George N. White III

341-355

 

 

A semi-analytic seasonal algorithm to retrieve chlorophyll-a concentration in the Northwest Atlantic Ocean from SeaWiFS data

      *E. Devred, C. Fuentes-Yaco, S. Sathyendranath, C. Caverhill, H.Maass, V. Stuart, T. Platt & G. White

356-367

 

 

Artificial neural networks (ANN) based algorithms for chlorophyll estimation in the Arabian Sea

       *Prakash Chauhan, P.V. Nagamani & Shailesh Nayak

368-373

 

 

Detection of Trichodesmium bloom patches along the eastern  

      Arabian Sea by IRS-P4/OCM ocean color sensor and by

       in situ measurements

       *Elgar Desa, T. Suresh, S.G.P. Matondkar, Ehrlich Desa, J. Goes, A.Mascarenhas, S.G. Parab, N. Shaikh & C.E.G. Fernandes

374-386

 

 

Use of the first and second chlorophyll absortion bands

        for marine biogeochemical patch recognition

        Karl Heinz Szekielda

387-395

 

 

Applications of remotely-sensed ocean colour data in the 

       Arabian Sea: A review

       *L.J. Watts, Beena Kumari & H. Maass

396-407

 

 

Satellite-derived total and new phytoplankton production in the

       Gulf of Mexico

        Raquel M. Hidalgo-Gozalez, *Saul Alvarez-Borrego, Cesar Fuentes-Yaco & Trevor Platt

408-417

 

 

Decadal variability in the Yellow and East China Seas

        as revealed by satellite ocean colour data (1979-2003)

       *SeungHyun Son, Janet Campbell, Mark Dowell & Sinjae Yoo

418-429

 

 

Exploration of fishery resources through integration of

     ocean colour with sea surface temperature: Indian experience

     *R.M. Dwivedi, H.U. Solanki, S.R. Nayak, D. Gulati &  V.S. Somvanshi

430-440

 

 

Application of QuikSCAT SeaWinds data to improve

        remotely sensed Potential Fishing Zones (PFZs)

        forecast methodology: Preliminary validation results

        *H.U. Solanki, Yashwant Pradhan, R.M. Dwivedi , Shailesh Nayak, D. Gulati & V.S. Somvanshi

441-448

 

 

A persistent eddy in the central Arabian Sea: Potential

         trophic significance

        *Beena Kumari, H.Maass, R.C.Panigrahy & R.R. Navalgund

449-458

 

 

Coastal processes along the Indian coast-Case studies based on synergistic use of IRS-P4 OCM and IRS-1C/1D data

      *A.S. Rajawat, Mukesh Gupta, Yashwant Pradhan,  A.V. Thomaskutty & Shailesh Nayak

459-472

 

 

 

 

Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp.333-340

 

 

Remote sensing of ocean colour: Towards algorithms for retrieval of
pigment composition

*Shubha Sathyendranath1,2, Venetia Stuart1, Trevor Platt2, Heather Bouman2, Osvaldo Ulloa3 & Heidi Maass2

Oceanography Department, Dalhousie University, Halifax, Nova Scotia, B3H 4J1 Canada

Biological Oceanography, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2 Canada

Universidad de Concepción, Departamento de Oceanografía & Centro de Investigación Oceanográfica COPAS,
Casilla 160-C, Concepción, Chile

*[E-mail: shubha@dal.ca]

Received 1 November 2004, revised 6 April 2005

Ocean colour varies as an inverse function of the absorption coefficient. In Case 1 waters, phytoplankton are known to be the principal agents responsible for variations in the total absorption coefficient. The concentration and composition of pigments present have a strong influence on phytoplankton absorption spectra. Empirical (regression) algorithms exist to recover the wavelength-specific absorption coefficient of phytoplankton from the concentration of the main pigment, chlorophyll-a. However, to explain the residuals about such regressions remains a major challenge. We have analysed a set of over 1,600 absorption spectra of phytoplankton collected from various oceanographic provinces. In parallel, we examined the corresponding pigment complexes, as revealed by High Performance Liquid Chromatography (HPLC). We have uncovered broad trends in the shapes of the absorption spectra and in the pigment complexes, consequent upon changes in the pigment biomass, with clear implications for the remote sensing of ocean colour.

[Key words: Ocean colour, phytoplankton pigments, absorption spectra, remote sensing]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 341-355

 

Comparison of in situ and remotely-sensed (SeaWiFS) chlorophyll-a in the Northwest Atlantic

César Fuentes-Yaco1,2*, Emmanuel Devred1,2, Shubha Sathyendranath1,2, Trevor Platt2, Linda Payzant2, Carla Caverhill2,
Cathy Porter2, Heidi Maass2, George N. White III2

Department of Oceanography, Dalhousie University, Halifax, NS, B3H 4J1, Canada

Department of Fisheries and Oceans, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth,

  NS, B2Y 4A2, Canada

*[E-mail: Fuentes-YacoC@mar.dfo-mpo.gc.ca]

Received 1 November 2004, revised 6 April 2005

Field measurements of phytoplankton pigment (chlorophyll-a) from the Northwest Atlantic are compared with concurrent pigment concentrations derived from SeaWiFS data using NASA/SeaDAS algorithms known as Ocean Chlorophyll 2 (OC2) and OC4 (versions 4.1 and 4.3). The results showed broad agreement but estimates using the NASA algorithms tended to show uncertainties, with lower than in situ values at concentrations greater than 1 mg chl-a m-3. Regionally -, and seasonally-, adapted empirical corrections are developed in an attempt to reduce the bias. The magnitude of errors was quantified using linear regression. Further progress will require application of a theoretical regional ocean-colour model.

[Key words: Ocean colour, remote sensing, SeaWiFS, chlorophyll-a, phytoplankton pigment, Northwestern Atlantic]

[IPC Code: Int.Cl.7 G01J 3/28, G06K 7/10]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 356-367

 

 

A semi-analytic seasonal algorithm to retrieve chlorophyll-a concentration in the Northwest Atlantic Ocean from SeaWiFS data

E. Devred1,2,*, C. Fuentes-Yaco1,2, S. Sathyendranath1,2, C. Caverhill2, H. Maass2, V. Stuart1,2,
T. Platt2 & G.  White2

Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1, Canada. 

Biological Oceanography Division, Bedford Institute of Oceanography, Box 1006, Dartmouth,

Nova Scotia, B2Y 4A2, Canada

*[E-mail: DevredE@mar.dfo-mpo.gc.ca]

Received 1 November 2004, revised 27 June 2005

In a companion paper [Fuentes-Yaco et al., Indian J. Mar. Sci., 34(2005),.341-355], it was demonstrated that the SeaWiFS OC4 algorithm, applied to the Northwest Atlantic, resulted in a systematic bias in the retrieved chlorophyll-a concentration. Their comparison of satellite-derived chlorophyll-a values with matching in situ observations showed that the OC4 algorithm as implemented in the NASA SeaDAS software package, overestimated chlorophyll-a in waters with low pigment concentrations, and underestimated chlorophyll-a for high pigment concentrations. In this paper, we seek an explanation for the observed bias, using a semi-analytic model of ocean colour [Sathyendranath et al., Int. J. Remote Sens, 22(2001), 249-273] modified to account for seasonal and regional variations in the spectral absorption properties of phytoplankton, dissolved matter (yellow substances) and detritus. The model is also extended into the near infrared region to evaluate the possible impact on the atmospheric correction algorithm. The results indicate that much of the bias can be explained by local variations in the inherent optical properties of particulate and dissolved matter present in the region. The algorithm based on the semi-analytical model eliminates practically all the bias (inaccuracy) in the retrieved chlorophyll-a concentrations, but does not improve the precision of retrieval.

[Key words: Ocean colour, SeaWiFS, remote-sensing, reflectance, chlorophyll a, Northwest Atlantic Ocean, algorithm]

[IPC Code: Int.Cl.7 G01D 21/00, G06K 7/10]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 368-373

 

 

Artificial neural networks (ANN) based algorithms for chlorophyll estimation
in the Arabian Sea

*Prakash Chauhan,  P.V. Nagamani & Shailesh Nayak

Marine and Water Resources Group, Space Applications Centre, Ahmedabad 380015, India

*[E-mail: prakash@sac.isro.org]

Received 1 November 2004; revised 31 May 2005

In-situ bio-optical measurements were collected during six ship campaigns in the north eastern Arabian Sea using SeaWiFS Multi-channel Profiling Radiometer (SPMR). An artificial neural network (ANN) based algorithms were constructed to estimate oceanic chlorophyll concentration using in-situ data. The different ANNs were obtained by systematic variations of architecture of input and hidden layer nodes for the Arabian Sea training data set. The performance of individual ANN-based pigment estimation algorithm was evaluated by applying it to the remote sensing reflectance data contained in validation data set. The performance of the most successful ANN was compared with commonly used empirical pigment algorithms. Compared to e.g. the SeaWiFS algorithms Ocean Chlorophyll-2 (OC2) and Ocean Chlorophyll-4 (OC4), the square of the correlation coefficient r2 is increased from 0.69 for OC4, respectively 0.70 for OC2 to 0.96 for ANN algorithm. The RMS error of the estimated log-transformed pigment concentration dropped from 0.47 for OC2, respectively 0.41 for OC4 to 0.11 for ANN-based pigment algorithm.

[Key words: Artificial Neural Network (ANN), ocean colour, chlorophyll, Arabian Sea, algorithms]

[IPC Code: Int.Cl.7 G06N 3/02]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp.374-386

 

 

Detection of Trichodesmium bloom patches along the eastern Arabian Sea
by IRS-P4/OCM ocean color sensor and by in-situ measurements

*Elgar Desa, T.Suresh, S.G.P.Matondkar, Ehrlich Desa, § J.Goes, A. Mascarenhas, S.G.Parab,
N.Shaikh & C.E.G.Fernandes

National Institute of Oceanography, Dona Paula, Goa 403 004, India

*[E-mail : elgar@darya.nio.org]

Received 1 November 2004; revised 31 May 2005

The detection of blooms of the marine cyanobacterium Trichodesmium from space has been studied using high resolution ocean color imagery in the visible wavebands of the OCM monitor (Ocean Color Monitor) on the IRS-P4 satellite platform. The standard detection protocol developed by Subramaniam et al. [Deep-Sea Res-II, 49 (2002) 107-121], has been used in this paper. Localized bands of Trichodesmium were detected in OCM imageries of 16th,18th, 20th and 22nd March 2002 in decreasing numbers with time. The patches were aligned approximately parallel to the shoreline, and distributed over the shallow waters off the west coast of India. An analogous search of Trichodesmium bloom patches for these days using available SeaWiFS (Sea Viewing Wide field of View Sensor) sensor revealed features of reduced spatial resolution compared to that observed by the higher resolution OCM sensor, and at locations further offshore. In a field study during 19th to 22nd March 2002, we encountered Trichodesmium patches (~ 90 km ) off the coast of Goa. Microscopic analysis confirmed that these patches belonged to the Trichodesmium erythraeum. These field patches were further offshore from the positions occupied by the near-shore patches seen in the OCM imageries during 18th to 22nd March 2002. Radiometric measurements made in the cruise-detected patches show water leaving radiances averaging ~ 1 μW/cm2/nm, below the detection threshold of the present satellite detection scheme. It is clear that further efforts are needed to improve the detection range of present protocols so as to detect the presence of less reflective Trichodesmium patches of the type encountered during our cruise.

[Key words : Trichodesmium, detection, Ocean Color Monitor, radiometer, trichomes, SeaWiFs, chlorophyll,  

                       Arabian Sea]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp.387-395

 

 

Use of the first and second chlorophyll absorption bands for marine biogeochemical patch recognition

Karl Heinz Szekielda

Geography Department, Hunter College City, University of New York, 695 Park Avenue
New York, NY 10021, U.S.A.

[E-mail: szekielda@aol.com ]

Received 23 February 2004, revised 21 June2005

Water-leaving spectral signatures were used in the spectral regions where chlorophyll has its first and second absorption bands in order to recognize biogeochemical provinces in the pelagic and coastal ocean. The analysis of spectra collected in eutrophic coastal waters identified a very narrow spectral bandwidth in which the highest correlation between chlorophyll and the first derivative is apparent. A ratio technique using the defined envelope showed that a good relationship exists between the ratio of the reflectance R667/R678 and surface chlorophyll concentrations. The global data set for MODIS 3 used in this study data has a 4.89-km pixel resolution that is mapped on a cylindrical equidistant map projection. The data presented are based on an interpretation of the ratios R443/R551 and R678/R667 that use the spectral region of the two absorption bands of chlorophyll, the fluorescence of chlorophyll at 678 nm und the hinge point at 551 nm. The two selected ratios indicate the response of provinces according to the depth location of absorbing pigments as well as the overall response to integrated concentrations of pigments in the euphotic zone. The results show that biogeochemical provinces can be identified by the ratio technique and upwelling regions, current systems and river discharge can be spectrally separated.

[Key words: Remote sensing, biogeochemical provinces, chlorophyll, current systems, image processing, MODIS.]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp.396-407

 

Applications of remotely-sensed ocean colour data in the Arabian Sea: A review

L. J. Watts1*, Beena Kumari2 & H. Maass3

1* Natural Environment Research Council Centres for Atmospheric Science (NCAS), c/o NERC Science Programmes Directorate, Swindon, Wiltshire, SN2 1EU, UK.

2 Marine and Water Resources Group, Space Applications Centre (ISRO), Ahmedabad, Gujarat, 380 015, India

3 Biological Oceanography Division, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia,
B2Y 4A2, Canada

*[E-mail: lw@nerc.ac.uk]

Received 1 November 2004, revised 7 July 2005

Biological oceanography has been revolutionised by the provision of remotely sensed ocean colour data. These data provide us with a two-dimensional window into the synoptic state of the ecosystem by providing information on the surface biomass fields. This paper considers the advances made in the field of biogeochemical studies in the Arabian Sea through the exploitation of such remotely sensed ocean colour data. It concentrates on the advances made within the framework of the Joint Global Ocean Flux Study (JGOFS), focussing on the period 1994-1996 when the ARABESQUE (UK contribution to JGOFS) oceanographic campaigns took place. It considers the ocean-colour data and algorithms that were available during this period and how they have been used in biogeochemical studies of the area. It then considers advances in the post-JGOFS era and concludes with some recommendations for future studies in the Arabian Sea area. These include: the requirement for further development of regional algorithms for the retrieval of chlorophyll-a concentrations from ocean-colour data, due to the temporal and spatial variation of the bio-optical properties observed in the near- and surface waters, within and between the seasons; the further collection of shipboard measurements of P-I parameters, light absorption and pigment data throughout the year and further development of protocols for assigning these parameters to the Arabian Sea area, in the quest to improve primary production estimates on an ocean-basin scale.

[Key Words: Algorithm, Arabian Sea, biogeochemistry, bio-optical properties, chlorophyll-a, CZCS, JGOFS, 

            ocean colour, phytoplankton, primary production, new production, satellite remote sensing, SeaWiFS]

 

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 408-417

 

Satellite-derived total and new phytoplankton production in the Gulf of Mexico

Raquel M. Hidalgo-González1, Saúl Alvarez-Borrego1*, César Fuentes-Yaco2, 3, Trevor Platt2

1 Department of Ecology, Division of Oceanology, CICESE, Km. 107 Carretera Tijuana-Ensenada, Ensenada,
Baja  California, México

2 Department of Fisheries and Oceans, Bedford Institute of Oceanography, Ocean Sciences Division, Box 1006,
Dartmouth,  Nova Scotia B2Y 4ª2, Canada

3 Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, B3H 4JI, Canada

*[E-mail: alvarezb@cicese.mx]

Received 23 February 2005, revised 7 July 2005

Integrated total (PTint) and new production (Pnewint) (gC m-2 d-1) were calculated for the Gulf of Mexico with semi-analytical models from the literature, using chlorophyll a concentrations (Chlsat) and the vertical attenuation coefficients of light (K490) from monthly composites of the satellite sensor SeaWIFS (1997–2004). The phytoplankton biomass vertical distribution associated with Chlsat, and the vertical distribution of the f-ratio [f(z) = Pnew(z)/PT(z)], were deduced from historic oceanographic data. Based on bathimetry, surface T oC, Chl and nutrients, the Gulf was partitioned into three regions: Yucatan, Deep-waters, and Mississippi. The year was divided into two periods for the Deep-waters region, “cool” and “warm.” The whole year was treated as a single period for the Yucatan and Mississippi regions. Average values for PTint had a significant seasonal variation for the Deep-waters region (0.37-0.44 and 0.22-0.24 gC m-2 d-1, for the “cool” and “warm” periods, respectively), and similarly for Pnewint (0.023-0.026 and 0.013-0.014 gC m-2 d-1). Ranges for the average PTint values were 1.18 – 1.22, and 1.60 – 1.68 gC m-2 d-1, for the Yucatan and Mississippi regions, respectively. Ranges for Pnewint were 0.97 – 1.05, and 1.38 – 1.44 gC m-2 d-1. The present, limited data, do not show a significant interannual PTint and Pnewint variability in any region of the Gulf. Longer satellite time series for more complete future work may lead to the description of significant interannual primary production variability in the Gulf.

[Key words: Gulf of Mexico, chlorophyll, remote sensing, primary production, f-ratio]

Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 418-429

 

Decadal variability in the Yellow and East China Seas as revealed by
satellite ocean color data (1979–2003)

SeungHyun Son1,2,6,*, Janet Campbell3, Mark Dowell4, & Sinjae Yoo5

1 Department of Oceanography, Dalhousie University, Halifax, NS, B3H 4R2, Canada

2 Department of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, NS, B2Y 4A2, Canada

3 Ocean Process Analysis Lab., University of New Hampshire, Durham, NH 03824, USA

4 Institute for Environment and Sustainability, Joint Research Centre, Ispra, I-21020, Italy

5 Korea Ocean Research and Development Institute, Ansan, South Korea

*[E-mail : SeungHyun_Son@umit.maine.edu]

Received 17 October 2005

Satellite ocean color data from the Coastal Zone Color Scanner (CZCS) in 1979 to 1984 and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) in 1998 to 2003 are examined to determine whether there have been changes in chlorophyll concentration and suspended sediment as indicated by changes in satellite-derived optical properties during the past two decades in the Yellow and East China Seas (YECS). We compare water-leaving radiance measurements at 443 and 555 nm [the CZCS band is centered at 550 nm, but we consider this comparable to the SeaWiFS 555-nm band] and discuss possible reasons for the changes observed. The shallow coastal areas of the YECS exhibited high water-leaving radiance in the 555-nm band (Lw555) during two time periods, indicating that these waters are sediment-dominated Case-2 waters. Between the CZCS era and the SeaWiFS era, Lw443 increased in these areas by 17%-61%, and Lw555 increased by 67-108%. In the deeper waters, Lw443 decreased by 25%-31%, which would indicate an increase in absorbing materials such as chlorophyll and colored dissolved organic matter (CDOM). Between the CZCS and SeaWiFS eras, the average chlorophyll concentration (based on Case-1 algorithms) increased by 15-60% in these offshore deep waters. Periodical in situ measurements from 61 stations in the western coast of Korea from 1978 and 2002 were compared with the trends found in satellite data. The results show that there were increasing trends in temperature and zooplankton biomass, and decreasing trends in salinity and Secchi depth. The satellite data surrounding these stations showed an increase in Lw555 (49 %), a decrease in the Lw443 (-12 %), and an increase in chlorophyll (46 %). From the results, it is inferred that there have been environmental changes in the Yellow Sea during the last two decades from 1979 to 2003.

[Key words: Decadal variability, ocean color data, CZCS, SeaWiFS, Yellow Sea, East China Sea, satellite ocean colour]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp.430-440

 

 

Exploration of fishery resources through integration of ocean colour
with sea surface temperature: Indian experience

R.M. Dwivedi1*, H.U. Solanki1, S.R. Nayak1, D. Gulati2 & V.S. Somvanshi2

1Space Applications Centre, Ahmedabad 380 015, India

2Fishery Survey of India, Mumbai 400 001, India

*[E-mail: rmdwivedi@rediffmail.com]

Received 1 November 2004; revised 12 May 2005

Exploration of fishery resources using remote sensing technique is based on the principle of identification of feeding grounds where fish tend to accumulate. It has been proven that thermal or colour gradients revealed by oceanic fronts indicate sites of high biological productivity. Some constraints in using SST (sea surface temperature) gradients for locating fish in the Indian waters were experienced such as the narrow range of SST and difficulty in detecting gradients, particularly in summer. Two approaches were developed and validated in the coastal waters of the west coast of India. In the first approach, SST contours (using NOAA AVHRR) were overlaid on chlorophyll image (from IRS P4 OCM) of corresponding date. This enabled identification of common frontal structures from the composite product. These sites were selected as priority fishing zones for the trial forecasts. Besides, ocean colour images were found to provide information on additional productive areas not found from SST images alone and hence, a second approach made exclusive use of patterns of ocean colour. Merits of ocean colour arose from penetration of visible radiation below surface up to one attenuation depth and from the frequent repeat cycle of the satellite data. The improvements with use of ocean colour include capability of prediction of oceanic features, exploitation of knowledge of the history of the features, identification of biological fronts in the deep sea waters etc. Also, such features as non-toxic winter blooms and internal waves were identified in the deep waters of the Northern Arabian Sea using chlorophyll images and the response of fish to these features was studied. This paper highlights how ocean colour improves our ability to locate areas of high abundance of fish. Because the time taken in information extraction from satellite data is a critical factor, on-line reception of OCM and AVHRR data was arranged. Fishery forecasts were generated using the integrated approach within 24 hours of satellite over pass, and disseminated to collaborating agencies for follow up fishing operation. The validation experiment for the forecasts was carried out for three years covering different seasons during 1999-2001. It was found that the forecasts were superior in terms of rate of success and magnitude of fish catch. Summary of feedback received indicated 70-90 % success rate (reliability) of the forecasts and 70-200 % increase in catch. In comparison with this, earlier SST-based approaches for the forecast yielded 50 % success rate and 40-50 % increase in catch. The integrated approach is currently being used to generate nation-wide fishery forecasts. In addition to this, cost-benefit analysis for the satellite fishery forecasts was also attempted. It was observed that the benefit:cost ratio increased from 1.27 to 2.12 for bottom trawling and 1.3 to 2.14 for gillnet fishing with the use of satellite forecasts.

[Key words: Fishery, remote sensing, ocean colour, chlorophyll, SST, deep sea resources, cost-benefit analysis

 

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp.441-448

 

Application of QuikSCAT SeaWinds data to improve remotely sensed Potential Fishing Zones (PFZs) forecast methodology: Preliminary validation results

*H.U. Solanki, Yashwant Pradhan, R.M. Dwivedi & Shailesh Nayak

Marine and Water Resources Group, Remote Sensing and Image Processing Area, Space applications Centre (ISRO)
Ahmedabad 380 015, India

and

D.K. Gulati & V.S. Somvamshi

Fishery Survey of India, Sir P.M. Road, Botawala Chamber, Mumbai 400 001, India

*[E-mail: himmatsinh@sac.isro.org]

Received 1 November 2004, revised 7 July 2005

In this study, we used chlorophyll concentration and sea surface temperature (SST) images derived from IRS P4-OCM and NOAA- AVHRR, respectively, to delineate the oceanographic features exhibiting different oceanic processes. QuikSCAT-SeaWinds derived wind vectors were used to understand, establish, quantify and to demonstrate the variability of wind induced watermass flow as well as their impacts on features/oceanographic process. Oceanographic features like eddies, rings and fronts were found shifted as per movement and direction of the wind. The movement of water mass due to wind provides insight of environmental factors relevant to dispersal of fishery resources. An algorithm was developed to compute water mass transport and feature shift. Based on these studies an approach for incorporating QuikSCAT-SeaWinds data to improve PFZs forecast methodology has been developed. The improved PFZs forecast methodology was validated through near real time fishing operations. About 82-85% success rate was reported during validation experiments carried out during 2004. The improved methodology would prolong the validity of PFZs forecast.

[Key words: Ocean colour, OCM, SeaWinds, QSCAT, fishing zones]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 449-458

 

A persistent eddy in the central Arabian Sea: Potential trophic significance

*Beena Kumari1, H. Mass2, R. C. Panigrahy3 & R. R. Navalgund4

1 Marine and Water Resources Group, Space Applications Centre, ISRO, Ahmedabad, Gujarat, 380 015, India

2 Biological Oceanography Division, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia,
B2Y 4A2, Canada

3 Department of Marine Sciences, Berhampur University, Berhampur, Orissa, 760 007, India

4 National Remote Sensing Agency, Department of Space, Balanagar, Hyderabad, Andhra Pradesh, 500037, India

*[E-mail: beena@sac.isro.gov.in]

Received 1 November 2004; revised 8 June 2005

Arabian Sea is an area of strong currents, complicated flow patterns with several eddies and semi annually reversing monsoon winds. This paper deals with a cold eddy highly rich in phytoplankton in the Central Arabian Sea, centered around: 14° 25’ N and 69° 20’ E during January – March 1998. The eddy was about 100 km in diameter with a depth of about 4000 m and maximum chlorophyll-a concentration was 1 mg m-3 compared with 0.2 mg m-3 in the surrounding areas. Average optical depth of the area was 12 m. The occurrence of the eddy and the related oceanographic variables were inferred from SeaWiFS derived chlorophyll-a (Chl-a), NOAA Pathfinder AVHRR derived sea surface temperature, sea surface height from TOPEX altimeter and collateral information. The cold eddy formation is probably due to longshore density variation in the ocean. Due to negative sea level anomalies, associated surface divergence and upwelling process, the region of cold eddy is known to be highly productive. The cold eddy in the same location was observed during January 2000. The persistence of the eddy for more then a month indicates that this area is a rich forage ground for tuna fishery.

[Key words: Arabian Sea, chlorophyll, cold eddy, SST, OCM, SeaWiFS, tuna, fishery]

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Indian Journal of Marine Sciences

Vol. 34(4), December 2005, pp. 459-472

 

 

Coastal processes along the Indian coast – Case studies based on synergistic use of IRS-P4 OCM and IRS-1C/1D data

·  A.S. Rajawat, Mukesh Gupta, Yaswant Pradhan, A.V. Thomaskutty &  Shailesh Nayak

Marine and Water Resources Group, Space Applications Centre, ISRO, Ahmedabad-380 015, India

·          [E-mail: asrajawat@sac.isro.gov.in]

Received 1 November 2004; revised 31 May 2005

The sequential Suspended Sediment Concentration (SSC) maps were generated using IRS-P4 OCM (Ocean Color Monitor) data for selected tide dominated, wave dominated and deltaic coasts around the Indian subcontinent. Patterns of SSC were studied to understand the sediment dynamics, circulation patterns, fronts and consequent impact on coastal processes.  Hitherto, unknown sediment plumes extending for large distance into deep offshore areas could be identified from the major deltaic regions. The high temporal capability of OCM data was extremely useful to understand sediment dynamics in tide-dominated regions of the Gulf of Khambhat, the Gulf of Kachchh and the Hoogli estuary.  SSC maps in conjunction with corresponding tide and bathymetry data could be sequenced as per flooding and ebb cycles.  Development, formation, shifting nature of shoals and sediment curls during a tide cycle could be studied. It is observed that during the North-East (NE) monsoon suspended sediment influx of the Ganga-Brahmaputra system influences the coastal processes along the continental margins of the Orissa and the Northern Andhra Pradesh along east coast of India. The occurrence of cyclone aids in entrapment of fluvial discharge into the coastal waters, leading to a reduced offshore influx into deeper regions of the Bay of Bengal and high sedimentation near to the coast. Seasonal changes along wave-dominated west coast showed net sediment transport from north to south in the pre-monsoon season and south to north in post-monsoon season.   Significant onshore- offshore transport along west coast was also observed. The impact of the regional sediment dynamics on the site-specific local coastal environment was studied by integrating observations derived from OCM and IRS-1C/1D data.  The paper concludes the utility of Ocean Color Monitor and IRS-1C/1D data in studying various coastal processes and regional sediment dynamics.

[Key words: Coastal processes, IRS-P4 OCM, IRS-1C/1D, suspended sediments, sediment dynamics, shoreline changes]

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Acknowledgement  to  Referees [2005]

 

The Publisher and Editor of the Indian Journal of Marine Sciences (IJMS) are most grateful to the experts given below, in assisting the peer-review process of the journal. The referees have spared some of their valued time on critically reviewing the research papers submitted to IJMS during the year 2005. Their kind cooperation in critical reviewing, at times re-reviewing, is highly appreciated, which has immensely helped in maintaining the quality of the papers published in IJMS. We are thankful to them for their continuing efforts..

 


Abraham, T.J., West Bengal, India

Achuthankutty, C.T., Goa, India

Almogi-Labin, Ahura, Jerusalem, Israel

Andersen, Frede O., Odense, Denmark

Anil, A.C., Goa, India

Anton, Josefa, Alicante, Spain

Bacelar Nicolau-Paula, Lisboa,Portugal

Bailey, S.,Warwick, U.K.

Balestri, Elena, Pisa, Italy

Banakar, V.K., Goa, India

Bashan, Yoav, La Paz, Mexico

Becker, S., Bristol, U.K.

Berghe, Edward V., Oostende, Belgium

Bhaskar, N., Mysore, India

Bhatta, Ramachandra, Mangalore,India                     

Billup, Katharina, Delaware, U.S.A.

Boday, A.C., L’Houmeau, France

Bright Singh, I.S., Cochin, India

Bye, J.A.T., Melbourne, Australia

Chavan, O.S., Goa, India

D’Odorico, Paolo, Virginia, U.S.A.

D’Souza, L, Goa, India

Dalal, S.G., Goa, India

Davis III, Stephen E., Texas, U.S.A.

Deo, M.C., Mumbai, India

Eguchi, Nobuhisa O., Hokkaido, Japan

Ernst, S. R., Utrecht, The Netherlands

Erzini, Karim, Faro, Portugal

 

Fenical, William, California, U.S.A.

Gailott, Phillippe, Yokohama, Japan

 Garcia-Fernandez, Jordi, Barcelona, Spain

Gimeno, Luis, de Vigo, Spain

Gomez-Gil, Bruno, Mazatlan, Mexico

Grevemeyer, Ingo, Kiel, Germany

Hakanson, Lars, Uppsala, Sweden

Harkanta, S.N., Goa, India

Hayes, Angela, Limerick, Ireland

Heinz, Petra, Tuebingen, Germany

Helle, Kristin, Bergen, Norway.

Ho, Yuh-Shan, Taipei, Taiwan

Jaiswar, Jiyalal Ram M, Bombay, India

John Forsythe, M.S., Texas, U.S.A.

Kamermans, Pauline, Yerseke, The Netherlands

Karunasagar, I., Mangalore, India

Kiil, Soren, Lyngby, Denmark

Kim, Sang-Jin, Seoul, Korea

Konda, M., Kyoto, Japan

Konstantinou, I, Loannina, Greece

Krishnaswami, S., Ahemdabad, India

Kucera, Michal, Tubingen, Germany

Kumar, Sanil, Goa, India

Langezal, Sandra, Utrecht, The Netherlands

Lee, Richard, Savannah, U.S.A.

Lee, Sang-Han, Monaco, Spain

Longo, Sandro, Parma, Itlay

Lu, Lin, West, Vancouver, Canada

Malik, Anushree, New Delhi, India

McDaniel, Diane K., Kensington,USA

McGaan, Mary, Santacruz, U.S.A.

Mesquita, Analia, Goa, India

Mfilinge, Prosper L, Okinawa, Japan

Mishra, S.C., Chennai, India

Mistri, Michele, Ferrara, Itlay

Muniz, Pablo, Sao Paulo, Brasil

Muscheler, Raimund, Boulder, U.S.A.

Neelamani,S., Kuwait

Nicholson, Shaun, Wanchai, Honkong

Nigam, R., Goa, India

Nikitik, Chris, Cardif, U.K.

Paoletti, valeria, Salerno, Itlay

Peterson, Charles H., New Carolina, USA.

Pillai, N.G.K., Cochin, India

Poel, Gretta, Tasmania, Australia

Politris, Gerasinos K, Athens, Greece

Polnikov, V.G., Moscow, Russia

Potemra, James T., Hawaii, U.S.A.

Prakash, T. N., Trivandrum, India

Puelles, M.F. de, Palma de Marcella,Spain

Purnachandra Rao V., Goa, India

Rabouille, Christophe, Gif-sur-Yvette, France

Raghukumar, C., Goa, India

Rainbow, Philip S., London, U.K.

Rajagopal, S., Nijmegen, The Netherlands

Rajamanickam, G.V., Thanjavur, India

Rajan, Hkust, Hongkong

Rajendran, A., Tuticorin, India

Ramaiah, N., Goa, India

Ramesh, R., Ahmedabad, India

 

Rao, A.D., New Delhi, India

Rao, Subba, Surathkal, India

Ray, Bimalendu, Burdwan, India

Raymo, Maureen E., Boston, U.S.A.

Richardson, Gavin F, Charlottetown,  Canada

Rivonker, C.U., Goa, India

Rodrigues, C.L., Goa, India

Schellin, Thomas E., Hamburg,Germany

Schubert, Michael, Cedex, France

Seki, Hideshi, Hokkaido, Japan

Shankar D., Goa, India

Siddhanta, A.K., Bhavnagar, India

Soylemey, Muhittin, Istanbul, Turkey

Sprintall, Janet, La Jolla, U.S.A.

Srikrishna, Goa, India

Stal, Lucas J., Yerseke,T The Netherlands

Steeby, Jim, Belzoni, U.S.A.

Su, Fenzhen, Beijing, China

Sullivan, Lindsay, Narragansett, U.S.A.

Sundar, V., Chennai, India

Trott, Lindsay, Queensland, Australia

Ujiie, Hiroshi, Tokyo, Japan

Wafar, Mohideen, Goa, India

Wendler, Ines, Bremen, Germany

Wikner, J., Umea, Sweden

Yoo, Sinjae, Ansan, South Korea

Zhang, Quanbin, Qingdao, China

Zingde, M.D., Bombay, India