Madhupratap,M.,Gopalakrishnan,T.C.,Haridas,P.,Nair,K.K.C.
Mesozooplankton biomass, composition and distribution in the Arabian Sea during the Fall Intermonsoon: implications of oxygen gradients Journal Article
In: Deep-Sea Research Part II, vol. 48, no. 146, pp. 1345-1368, 2001.
Abstract | BibTeX | Tags: Arabian Sea, depth, diel, Distribution, migration, oxygen minimum, seasonal variation, south, thermocline
@article{,
title = {Mesozooplankton biomass, composition and distribution in the Arabian Sea during the Fall Intermonsoon: implications of oxygen gradients},
author = {Madhupratap,M.,Gopalakrishnan,T.C.,Haridas,P.,Nair,K.K.C.},
year = {2001},
date = {2001-01-01},
journal = {Deep-Sea Research Part II},
volume = {48},
number = {146},
pages = {1345-1368},
abstract = {Mesozooplankton biomass and distribution of calanoid copepods were studied for the upper 500m between 3 and 21§N along an open-ocean transect in the Arabian Sea during the Fall Intermonsoon (September-October 1992, 1993). The region studied has strong gradients in the oxygen minimum zone (OMZ), being acutely deficient in oxygen in the north and with increasing concentrations towards the south. In the upper layers, mesozooplankton biomass was higher in the northern latitudes, above the thermocline, apparently avoiding the OMZ. In the deeper strata, relatively higher biomass was observed in the more oxygenated southern latitudes. Highest mesozooplankton biomass in open waters of the Arabian Sea was observed during the intermonsoon seasons. Calanoid copepods occurred at all depths, and surface-living species did not undertake conspicuous diel migrations, even when they occurred in the deeper waters of the more southern latitudes. A few species belonging to the families Metridinidae and Augaptilidae appeared to be characteristic of the poorly oxygenated mid-depths of the more northern latitudes. Seasonal variations in the composition of the copepod community were negligible. The evolution of the OMZ in the Arabian Sea and its implications are discussed.},
keywords = {Arabian Sea, depth, diel, Distribution, migration, oxygen minimum, seasonal variation, south, thermocline},
pubstate = {published},
tppubtype = {article}
}
Mesozooplankton biomass and distribution of calanoid copepods were studied for the upper 500m between 3 and 21§N along an open-ocean transect in the Arabian Sea during the Fall Intermonsoon (September-October 1992, 1993). The region studied has strong gradients in the oxygen minimum zone (OMZ), being acutely deficient in oxygen in the north and with increasing concentrations towards the south. In the upper layers, mesozooplankton biomass was higher in the northern latitudes, above the thermocline, apparently avoiding the OMZ. In the deeper strata, relatively higher biomass was observed in the more oxygenated southern latitudes. Highest mesozooplankton biomass in open waters of the Arabian Sea was observed during the intermonsoon seasons. Calanoid copepods occurred at all depths, and surface-living species did not undertake conspicuous diel migrations, even when they occurred in the deeper waters of the more southern latitudes. A few species belonging to the families Metridinidae and Augaptilidae appeared to be characteristic of the poorly oxygenated mid-depths of the more northern latitudes. Seasonal variations in the composition of the copepod community were negligible. The evolution of the OMZ in the Arabian Sea and its implications are discussed.
Shi, W,Morrison, John M,Böhm, Emanuele,Manghnani, Vijayakumar
The Oman upwelling zone during 1993, 1994 and 1995 Journal Article
In: Deep Sea Research Part II: Topical Studies in Oceanography, vol. 47, no. 472, pp. 1227-1247, 2000, ISBN: 0967-0645.
Abstract | BibTeX | Tags: Arabian Sea, Hydro-biology, Interannual variability, oceanography, Oman, sea surface temperature, seasonal variation, Sultanate of Oman, Upwelling
@article{,
title = {The Oman upwelling zone during 1993, 1994 and 1995},
author = {Shi, W,Morrison, John M,Böhm, Emanuele,Manghnani, Vijayakumar},
issn = {0967-0645},
year = {2000},
date = {2000-01-01},
journal = {Deep Sea Research Part II: Topical Studies in Oceanography},
volume = {47},
number = {472},
pages = {1227-1247},
abstract = {Satellite-derived sea-surface temperature, TOPEX/POSEIDON (T/P) sea-level anomalies
(SLAs), model wind data, and hydrographic data are used to characterize the upwelling along
the Oman coast during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea
Process Study (ASPS) in 1995 as well as to look at interannual variability in the upwelling over
the period 1993}1995.
Empirical orthogonal function (EOF) analysis of the satellite-derived sea-surface temperature
(SST) at the locations of the US JGOFS standard stations shows the "rst mode, which
represents a biannual variability, contributes 67% of the total variance. In addition, the SST
shows the upwelling `fronta moving o!shore with the development of Southwest (SW) Monsoon
in early June 1995, reaching a maximum distance of approximately 120 km by late August
1995. Finally, SST shows the persistence of cold upwelling waters for nearly a month after the
end of the SW Monsoon within the bays along the Oman coast.
TOPEX/POSEIDON SLAs indicate that with the onset of the SW Monsoon, a 30-cm drop
in steric height is observed along the Oman coast associated the presence of the cool upwelled
waters. This drop in steric height sets up a horizontal pressure gradient and results in
a compensating along-shore, northeastward-#owing, geostrophic current (East Arabian
Current; EAC) during the SW Monsoon. Similarly, the altimeter data slow an o!shore decrease
in steric height during the Northeast (NE) Monsoon, indicating a seasonal reversal in direction
of the EAC with #ow to the southwest. Subsurface temperature data indicate that the actual
uplifting of isotherms associated with the upwelling can be found to a distance of approximately
260 km from the shore and to a depth of 150}200 m. Using along-track altimetry data, we
estimate that, for a region 260 km in o!shore distance and 600 km alongshore, 2.2]106,
1.4]106 and 0.55]106 m3 s~1 were upwelled through the 100 m level with upwelling velocities
O (2.0]10~5 m s~1), during the SW Monsoons of 1993, 1994 and 1995, respectively. The
reduced upwelling in the summer of 1995 is attributed to a reduction in wind-stress curl along
the Arabian coast when compared to 1993 and 1994. ( 2000 Elsevier Science Ltd. All rights
reserved.},
keywords = {Arabian Sea, Hydro-biology, Interannual variability, oceanography, Oman, sea surface temperature, seasonal variation, Sultanate of Oman, Upwelling},
pubstate = {published},
tppubtype = {article}
}
Satellite-derived sea-surface temperature, TOPEX/POSEIDON (T/P) sea-level anomalies
(SLAs), model wind data, and hydrographic data are used to characterize the upwelling along
the Oman coast during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea
Process Study (ASPS) in 1995 as well as to look at interannual variability in the upwelling over
the period 1993}1995.
Empirical orthogonal function (EOF) analysis of the satellite-derived sea-surface temperature
(SST) at the locations of the US JGOFS standard stations shows the "rst mode, which
represents a biannual variability, contributes 67% of the total variance. In addition, the SST
shows the upwelling `fronta moving o!shore with the development of Southwest (SW) Monsoon
in early June 1995, reaching a maximum distance of approximately 120 km by late August
1995. Finally, SST shows the persistence of cold upwelling waters for nearly a month after the
end of the SW Monsoon within the bays along the Oman coast.
TOPEX/POSEIDON SLAs indicate that with the onset of the SW Monsoon, a 30-cm drop
in steric height is observed along the Oman coast associated the presence of the cool upwelled
waters. This drop in steric height sets up a horizontal pressure gradient and results in
a compensating along-shore, northeastward-#owing, geostrophic current (East Arabian
Current; EAC) during the SW Monsoon. Similarly, the altimeter data slow an o!shore decrease
in steric height during the Northeast (NE) Monsoon, indicating a seasonal reversal in direction
of the EAC with #ow to the southwest. Subsurface temperature data indicate that the actual
uplifting of isotherms associated with the upwelling can be found to a distance of approximately
260 km from the shore and to a depth of 150}200 m. Using along-track altimetry data, we
estimate that, for a region 260 km in o!shore distance and 600 km alongshore, 2.2]106,
1.4]106 and 0.55]106 m3 s~1 were upwelled through the 100 m level with upwelling velocities
O (2.0]10~5 m s~1), during the SW Monsoons of 1993, 1994 and 1995, respectively. The
reduced upwelling in the summer of 1995 is attributed to a reduction in wind-stress curl along
the Arabian coast when compared to 1993 and 1994. ( 2000 Elsevier Science Ltd. All rights
reserved.
(SLAs), model wind data, and hydrographic data are used to characterize the upwelling along
the Oman coast during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea
Process Study (ASPS) in 1995 as well as to look at interannual variability in the upwelling over
the period 1993}1995.
Empirical orthogonal function (EOF) analysis of the satellite-derived sea-surface temperature
(SST) at the locations of the US JGOFS standard stations shows the "rst mode, which
represents a biannual variability, contributes 67% of the total variance. In addition, the SST
shows the upwelling `fronta moving o!shore with the development of Southwest (SW) Monsoon
in early June 1995, reaching a maximum distance of approximately 120 km by late August
1995. Finally, SST shows the persistence of cold upwelling waters for nearly a month after the
end of the SW Monsoon within the bays along the Oman coast.
TOPEX/POSEIDON SLAs indicate that with the onset of the SW Monsoon, a 30-cm drop
in steric height is observed along the Oman coast associated the presence of the cool upwelled
waters. This drop in steric height sets up a horizontal pressure gradient and results in
a compensating along-shore, northeastward-#owing, geostrophic current (East Arabian
Current; EAC) during the SW Monsoon. Similarly, the altimeter data slow an o!shore decrease
in steric height during the Northeast (NE) Monsoon, indicating a seasonal reversal in direction
of the EAC with #ow to the southwest. Subsurface temperature data indicate that the actual
uplifting of isotherms associated with the upwelling can be found to a distance of approximately
260 km from the shore and to a depth of 150}200 m. Using along-track altimetry data, we
estimate that, for a region 260 km in o!shore distance and 600 km alongshore, 2.2]106,
1.4]106 and 0.55]106 m3 s~1 were upwelled through the 100 m level with upwelling velocities
O (2.0]10~5 m s~1), during the SW Monsoons of 1993, 1994 and 1995, respectively. The
reduced upwelling in the summer of 1995 is attributed to a reduction in wind-stress curl along
the Arabian coast when compared to 1993 and 1994. ( 2000 Elsevier Science Ltd. All rights
reserved.
Measures,C.I.,Vink,S.
Seasonal variations in the distribution of Fe and Al in the surface waters of the Arabian Sea Journal Article
In: Deep-Sea Research Part II, vol. 46 , no. 153, pp. 1597-1622, 1999.
Abstract | BibTeX | Tags: Arabian Sea, Distribution, seasonal variation, Upwelling
@article{,
title = {Seasonal variations in the distribution of Fe and Al in the surface waters of the Arabian Sea},
author = {Measures,C.I.,Vink,S.},
year = {1999},
date = {1999-01-01},
journal = {Deep-Sea Research Part II},
volume = {46 },
number = {153},
pages = {1597-1622},
abstract = {Concentrations of dissolved Al and Fe in the surface mixed layer were measured during five cruises of the 1995 US JGOFS Arabian Sea Process Study, Concentrations of both Al and Fe were relatively uniform between January and April, the NE Monsoon and the Spring Intermonsoon period, ranging from 2 to 11 nM Al (mean 5.3 nM) and 0.5 to 2.4 nM Fe (mean 1.0 nM). In July/August, after the onset of the SW Monsoon, surface water Al and Fe concentrations increased significantly (Al range 4.5-20.1 nM; mean = 10 nM, Fe range 0.57-2.4 nM; mean = 1.3 nM), particularly in the NE part of the Arabian Sea, as the result of the input and partial dissolution of eolian dust. Using the enrichment of Al in the surface waters, we estimate this is the equivalent to the deposition of 2.2-7.4 g m-2 dust, which is comparable to values previously estimated for this region. Approximately one month later (August/September), surface water concentrations of both Al and Fe were found to have decreased significantly (mean Al 7.4 nM, mean Fe 0.90 nM) particularly in the same NE region, as the result of export of particulate material from the euphotic zone. Fe supply to the surface waters is also affected by upwelling of sub-surface waters in the coastal region of the Arabian Sea during the SW Monsoon. Despite the proximity of high concentrations of Fe in the shallow sub-oxic layer, freshly upwelled water is not drawn from this layer and the NO3/Fe ratio in the initially upwelled water is below the value at which Fe limitation is through to occur. Continued deposition of eolian Fe into the upwelled water as it advects offshore provides the Fe required to raise this ratio above the Fe limitation value. },
keywords = {Arabian Sea, Distribution, seasonal variation, Upwelling},
pubstate = {published},
tppubtype = {article}
}
Concentrations of dissolved Al and Fe in the surface mixed layer were measured during five cruises of the 1995 US JGOFS Arabian Sea Process Study, Concentrations of both Al and Fe were relatively uniform between January and April, the NE Monsoon and the Spring Intermonsoon period, ranging from 2 to 11 nM Al (mean 5.3 nM) and 0.5 to 2.4 nM Fe (mean 1.0 nM). In July/August, after the onset of the SW Monsoon, surface water Al and Fe concentrations increased significantly (Al range 4.5-20.1 nM; mean = 10 nM, Fe range 0.57-2.4 nM; mean = 1.3 nM), particularly in the NE part of the Arabian Sea, as the result of the input and partial dissolution of eolian dust. Using the enrichment of Al in the surface waters, we estimate this is the equivalent to the deposition of 2.2-7.4 g m-2 dust, which is comparable to values previously estimated for this region. Approximately one month later (August/September), surface water concentrations of both Al and Fe were found to have decreased significantly (mean Al 7.4 nM, mean Fe 0.90 nM) particularly in the same NE region, as the result of export of particulate material from the euphotic zone. Fe supply to the surface waters is also affected by upwelling of sub-surface waters in the coastal region of the Arabian Sea during the SW Monsoon. Despite the proximity of high concentrations of Fe in the shallow sub-oxic layer, freshly upwelled water is not drawn from this layer and the NO3/Fe ratio in the initially upwelled water is below the value at which Fe limitation is through to occur. Continued deposition of eolian Fe into the upwelled water as it advects offshore provides the Fe required to raise this ratio above the Fe limitation value.