Ms. Sushma G. Parab Profile

Sushma G. Parab

at National Institute of Oceanography

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Author

Publications (3)

Proceedings Article | 28 November 2006 Paper

Seasonality in subsurface chlorophyll maxima in the Arabian Sea: detection by IRS-P4/OCM and implication of it to primary productivity

S. G. Matondkar, Sushma Parab, R. Dwivedi

Proceedings Volume 6406, 64060X (2006) https://doi.org/10.1117/12.693691

KEYWORDS: Particle filters, Satellites, Water, Sensors, Fluorometers, Atmospheric modeling, Scintillation, Data modeling, Biology, Remote sensing

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Arabian Sea is highly influenced by monsoon systems like SW monsoon (June-September) and NE monsoon (December-February). This affects distribution pattern of phytoplankton, availability of nutrients and changing temperature specially during winter cooling period (February-March). These and other conditions like quality and quantity of light influence phytoplankton (type and concentration) in the Arabian Sea. In our study we have observed monsoon related peaks in phytoplankton and chlorophyll a in the Arabian Sea. These chlorophyll a (Chl a) concentrations detected by OCM sensor onboard IRS-P4 satellite is helping us to work out seasonality of phytoplankton in the Arabian Sea, which is of the great importance in the field of biology and biogeochemistry of this region. However, during these study subsurface chlorophyll a maxima (SCM) was observed as characteristics feature of chlorophyll a distribution in the Arabian Sea. The subsurface chlorophyll a maxima varies from 30m to 55m in the Arabian Sea during various seasons. During November at St. 1 surface chlorophyll a was 1.503 mgm^-3 and subsurface chlorophyll maxima was 12.692 mgm^-3. Similarly, at St. 13 surface chlorophyll a was 0.584 mgm^-3 and surface chlorophyll maxima was 8.517 mgm^-3. During upwelling, nutrients remained unused at sub surface due to shortage of light which may lead to subsurface blooms, detection of which is critical for precise estimation of chlorophyll a from ocean colour sensor. During our 5 year study (covering all the seasons) in northeastern (NE) Arabian Sea, we have observed more than 50 % stations were with subsurface chlorophyll a maxima where chlorophyll a was approximately 10 times higher compared to surface value. The high chlorophyll some time detected by OCM is mainly because of detection of subsurface chlorophyll maxima by the satellite but may not actually sampled during ship studies. The satellite penetration depth (ze), subsurface chlorophyll maxima depth, OCM derived chlorophyll a for different seasons in NE Arabian Sea is presented and discussed in this paper.

Proceedings Article | 28 November 2006 Paper

Basin scale distribution of Trichodesmium spp. in the Arabian Sea using Oceansat I/OCM

S. G. Matondkar, Sushma Parab, Elgar Desa, R. Dwivedi

Proceedings Volume 6406, 64060V (2006) https://doi.org/10.1117/12.693687

KEYWORDS: Water, Nitrogen, Oceanography, Data processing, Carbon, Remote sensing, Luminescence, Organisms, Profiling, Iodine

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Proceedings Article | 28 November 2006 Paper

Satellite and ship studies of phytoplankton in the northeastern Arabian during 2000-2006 period

S. G. Matondkar, R. Dwivedi, Sushma Parab, Suraksha Pednekar, E. Desa, A. Mascarenhas, Mini Raman, S. Singh

Proceedings Volume 6406, 64061I (2006) https://doi.org/10.1117/12.693693

KEYWORDS: Statistical analysis, Satellites, Water, Fluorometers, Satellite imaging, Taxonomy, Oceanography, Infrared imaging, Temperature metrology, Ocean optics

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Sequence of the images from IRS P4 / OCM satellite and extensive shipboard sampling programme are used to understand the seasonal variation of phytoplankton abundance and types in the Northeastern (NE) Arabian Sea and Lakshadweep Sea. An appreciable degree of spatial and temporal variability is observed in chlorophyll a distribution from November to April months, as well as coastal and offshore stations, indicating marked seasonality in phytoplankton distribution in NE Arabian Sea. During November month (fall intermonsoon) average chlorophyll a (Chl a) by fluorometer was (0.799 mgm^-3) and by OCM it was 0.584 mgm^-3. The higher chlorophyll a observed was due to Trichodesmium (cyanobacteria) blooms. During December the average chlorophyll a was 0.34 mgm^-3 also due to Trichodesmium filaments in water column. During January onwards winter cooling led to increase in nutrients which enhanced chlorophyll a value to 0.64 mgm^-3 due to growth of flagellates (as seen by high chlorophyll b besides chlorophyll a) in water column. February, March and April supported moderately high chlorophyll value (0. 3 to 0.5 mgm^-3) due to growth of prasinophytes (as seen by pigment prasinoxanthin) and blooms of the Noctiluca miliaris. Time series monitoring of Noctiluca bloom was also conducted using OCM based chlorophyll images in NE Arabian Sea. During February chlorophyll a retrieved by OCM was 0.3 to 0.9 mgm^-3. Pigment analysis of water samples indicated the equal important of accessory pigment like zeaxanthin, prasinoxanthin, beta-carotene. The relevance of these pigments estimated by HPLC like zeaxanthin (cyanobacteria), fucoxanthin (diatoms), peridinin (dinoflagellates) is presented and discussed. Similarly, exercise is conducted in Lakshadweep waters where Trichodesmium related peak in chlorophyll a was observed during March onwards in OCM data. The average chlorophyll a in NE Arabian Sea at surface during November was (0.726 mgm^-3), December (0.34 mgm^-3), January (0.723 mgm^-3), February (0.344 mgm^-3), March (0.963 mgm^-3) and April 0.665 mgm^-3. Similar trend was observed in primary productivity estimates. The attempt is made to work out seasonality in the productivity of the Arabian Sea using OCM derived chlorophyll and relation of enhancement in productivity due to development of winter blooms in the Arabian Sea. The environmental conditions (temperature, wind, nutrients and mixed layer depth) affecting these blooms responsible for year to year variation in bloom biomass and productivity is also presented in detail.

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