@article{,

title = {Intraseasonal variability in the southwestern Arabian Sea and its relation to the seasonal circulation},

author = {Brandt,P.,Dengler,M.,Rubino,A.,Quadfasel,D.,Schott,F.},

year  = {2003},

date = {2003-01-01},

journal = {Deep-Sea Research Part II},

volume = {50},

number = {333},

pages = {2129 -2141},

abstract = {An analysis of TOPEX/POSEIDON altimeter data and in situ current and temperature data obtained between April 1995 and October 1996 from a moored array shows strong intraseasonal fluctuations in the southwestern Arabian Sea, an oceanic region where the Great Whirl (GW), a predominantly wind-generated, very energetic anticyclone, is present during the Southwest Monsoon. Fluctuation periods between 30 and 50 days, up to 100 days during some years, are observed in the 8-year altimetric dataset, mostly during late summer and fall. These fluctuations are largest in a 1000 km-wide region off the Somali, Omani and Yemeni coasts north of 5§N, suggesting a local generation mechanism. The in situ data at different moorings show strong and coherent fluctuations that are characterized by southwestward phase propagation and northward energy propagation. Their periods range from 30 to 60 days and increase steadily from July 1995 to January 1996. In the first stage, these periods are at and below the cut-off period of freely propagating, first baroclinic mode Rossby waves, but approach this theoretical limit later in the year. Instabilities of the flow in the transition region between the Southern Gyre and the GW are likely sources of these fluctuations.},

keywords = {Arabian Sea, Oceanic, temperature},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Mesoscale eddies, costal upwelling, and the upper-ocean heat budget in the Arabian Sea},

author = {Fischer,A.S.,Weller,R.A.,Rudnick,D.L..,Eriksen,C.C.,Lee,C.M.,Brink,K.H.,Fox,C.A.,Leben,R.R.},

year  = {2002},

date = {2002-01-01},

journal = {Deep-Sea Research Part II},

volume = {49},

number = {94},

pages = {2231-2264},

abstract = {Estimationof the terms in the upper-ocean heat budget from a moored array in the central Arabian Sea shows periods when a rough balance between the temperature trend and the horizontal advection of heat exists. Altimetry and sea-surface temperature imagery are used to demonstrate that these episodes of strong horizontal advection are associated with mesoscale features. During the wintertime Northeast (NE) Monsoon these are capped-off mesoscale eddy features generated during the previous summertime Southwest (SW) Monsoon and have little horizontal transport of heat within the mixed layer. During the SW Monsoon the major contribution is strong offshore export of coastally upwelled water in a filament with a strong surface presence. Temperature and salinity properties from the moored array and a SeaSoar survey during the formation of the coastal filament confirm the offshore transport of the upwelled water mass to the site of the moored array, more than 600 km offshore. Estimates of the filament section heat flux are several percent of the total estimated heat flux due to upwelling along the Arabian Peninsula, and remote sensing data show that similar mesoscale variability along the coast is enhanced during the SW Monsoon. This points to the importance of mesoscale-modulated transports in not only the observed heat budget at the moored array, but in the overall upper ocean heat budget in the Arabian Sea},

keywords = {Arabian Sea, budget, salinity, survey, temperature, trend, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Zooplankton spatial distributions in coastal waters of the northern Arabian Sea, August 1995},

author = {Hitchcock,G.L.,Lane,P.,Smith,S.,Luo,J.G.,Ortner,P.B.},

year  = {2002},

date = {2002-01-01},

journal = {Deep-Sea Research Part II},

volume = {49},

number = {387},

pages = {2403-2423},

abstract = {The spatial distribution of zooplankton biomass was surveyed in coastal waters of the northern Arabian Sea during the 1995 Southwest Monsoon (August) on cruise MB 95-06 of the NOAA Ship Malcolm Baldrige.  Vertical patterns of displacement volumes from a limited set of paired day-night MOCNESS tows suggest there was little diel vertical migration in the coastal waters off the southern Arabian Peninsula. Zooplankton biomass varied from 5.2 to 15.1 9 dw m(-2) (178-517mM Cm-2) in the upper 200-300m of Omani coastal waters. Distributions of acoustic backscatter were mapped in eight daytime acoustic Doppler current profiler transects in coastal waters off Oman and Somalia. Several transects contained maxima in acoustic backscatter that coincided with cool, fresh surface features that were several tens of kilometers wide. Although there was considerable scatter in the relationship between acoustically determined biomass (ADB) of zooplankton and surface temperature, there was a trend of increased biomass in the cool surface temperatures of the Omani upwelling zone. Acoustic transects crossed two filaments that extended seaward from upwelling centers off Oman and Somalia. Estimated zooplankton ADB exported from the upwelling zones in the surface features was on the order of 300 kg dw s( -1 ). The physical and biological characteristics of filaments maintain zooplankton associated with upwelling areas, such as Calanoides carinatus, as they are advected offshore from coastal upwelling zones. (C) 2002 Published by Elsevier Science Ltd.},

keywords = {acoustic, Arabian Sea, displacement, Distribution, migration, Oman, surface temperature, temperature, trend, Upwelling, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Moored observations of upper-ocean response to the monsoons in the Arabian Sea during 1994-1995},

author = {Weller,R.A.,Fischer,A.S.,Rudnick,d.l.,Eriksen,C.C.,Dickey,T.D.,Marra,J.,Fox,C.,Leben,R.},

year  = {2002},

date = {2002-01-01},

journal = {Deep-Sea Research Part II},

volume = {49},

number = {253},

pages = {2195-2230},

abstract = {The role of surface forcing in the semiannual evolution of the upper-ocean temperature, salinity, and velocity fields in the Arabian Sea is examined. To do so, variability in the upper ocean in the central Arabian Sea was observed from an array of moorings deployed from October 1994 to October 1995. The Northeast (NE) Monsoon was characterized by moderate winds, clear skies, and dry air; sea-surface temperature (SST) dropped by 3§C; the ocean lost an average of 19.7Wm-2 and the mixed layer deepened by 100m in response. The Southwest (SW) Monsoon was accompanied by strong winds, cloudy skies, and moist air; the ocean gained an average of 89.5Wm-2 but SST dropped by 5.5§C and the mixed layer deepened to almost 80 m. The response to the NE Monsoon included daily cycling in the depth of the mixed layer in response to the diurnal cycle in the buoyancy forcing and a weak local, wind-driven response. Stronger windforcing during the SW Monsoon dramatically reduced diurnal restratification, and a clearer signal of local, wind-driven flow in the upper ocean was found. The strongest velocity signal in the upper ocean, however, was the flow associated with mesoscale geostrophic features that passed slowly through the moored array, dominating the current meter records in the first part of the NE Monsoon and again in the latter part of the SW Monsoon. One-dimensional heat and freshwater balances, which held at other times through the year, broke down during the passage of these features.},

keywords = {Arabian Sea, depth, salinity, temperature},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Physical forcing of biological productivity in the Northern Arabian Sea during the Northeast Monsoon},

author = {Kumar,S.P.,Ramaiah,N.,Gauns,M.,Sarma,V.V.S.S.,Muraleedharan,P.M.,Raghukumar,S.,Kumar,M.D.,Madhupratap,M.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48 },

number = {139},

pages = {1115-1126},

abstract = {Time-series observations at a nominally fixed location in the northern Arabian Sea (21§N, 64§E) during the Northeast Monsoon (winter, February) of l997 showed the prevalence of cold sea-surface temperatures (SST) and deep mixed layers resulting from winter cooling and convection. The covariation of nitrate concentrations in the surface layers and concentrations of chlorophyll a and primary production in the euphotic zone with mixed-layer depth (MLD) and wind suggests that carbon fixation was controlled primarily by physical forcing. Cooler waters during winter 1997 relative to winter 1995 were associated with deeper MLDs, higher nitrate concentrations, elevated primary productivity, and higher chlorophyll a concentrations, leading to the inference that even a 1§C decrease in SST could lead to significantly higher primary productivity. Satellite data on sea surface temperature (advanced very high-resolution radiometer; AVHRR) and TOPEX/POSEl- DON altimeter data suggest that this interannual variation is of basin-wide spatial scale. After the termination of winter cooling and subsequent warming during the Spring Intermonsoon, the Arabian Sea has low primary production. During the latter period, micro-organisms, i.e. heterotrophic bacteria and microzooplankton)-proliferate, a feeding mode through the microbial loop that appears to be inherent to mesozooplankton for sustaining their biomass throughout the year in this region.},

keywords = {Arabian Sea, chlorophyll, depth, feeding, lead, location, productivity, spatial scale, surface temperature, temperature},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Arabian Sea phytoplankton during Southwest and Northeast Monsoons 1995: composition, size structure and biomass from individual cell properties measured by flow cytometry},

author = {Shalapyonok,A.,Olson,R.J.,Shalapyonok,L.S.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48 },

number = {221},

pages = {1231-1261},

abstract = {As part of the US JGOFS Arabian Sea Process Study, we determined the abundance, size distributions and carbon biomass of autotrophic phytoplankton in the Arabian Sea during summer Southwest and fall Northeast Monsoon seasons of 1995 (R/V Thomas G. Thompson cruises TN 049 and TN 053). Flowcytometry of 60-ml samples was used to enumerate and determine scattering and fluorescence properties of Prochlorococcus sp., Synechococcus sp., and eukaryotic phytoplankton with cell equivalent spherical diameter up to 40 æm. Cellular forward light scattering was calibrated against Coulter size using 22 phytoplankton cultures spanning the size range 0.8-40 æm, grown exponentially in natural sunlight. The phytoplankton community structure was strongly linked to water-mass characteristics, and was affected by both intense monsoon-related environmental forcing and widespread and dynamic mesoscale structures; the magnitude of spatial variability was similar to that between seasons for all three phytoplankton groups. Prochlorococcus was numerically dominant in the more oligotrophic, stratified areas with surface nitrate concentrations below 0.1 æM and surface temperatures above 27§C. Its abundance was significantly greater during the NE Monsoon and was inversely correlated with the abundance of the two other groups. Synechococcus and eukaryotic phytoplankton cell concentrations covaried at most locations, were highest in areas of intense, monsoon-related mixing, and changed less between seasons than Prochlorococcus. The bulk of biomass of all three groups was located within the mixed layer. Only eukaryotes formed notable subsurface maxima at several offshore locations where Prochlorococcus dominated the mixed layer. Dramatically elevated eukaryotic phytoplankton concentrations in the nutrient-rich upwelling areas were due to the blooming of smaller (<3 æm) cells. Surprisingly, stratified, offshore, nutrient-depleted areas had concentrations of 10-40 æm phytoplankton cells similar to or even higher than upwelling areas. Thus, the mean eukaryotic cell size and the relative contribution of large nanoeukaryotes to the phytoplankton biomass were highest in offshore waters. Eukaryotes accounted for most of the phytoplankton carbon biomass - from about 50 to 80% on average during both seasons. Both Prochlorococcus and large (10 æm) nanoeukaryotes reached their greatest biomass contributions - up to 40% each - in the offshore oligotrophic locations. For the SW and NE Monsoon cruises, flow cytometrically-measured phytoplankton was estimated at 1.1 and 2.2 gCm-2 on average and comprised 33 and 38% of POC, respectively. Diel variability in cellular carbon content accounted for 52% of the observed variability in cellular carbon content for Prochlorococcus, 26% for Synechococcus, and 14% for eukaryotic phytoplankton cells at the surface.},

keywords = {abundance, Arabian Sea, diel, Distribution, location, surface temperature, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {A principal component analysis of sea-surface temperature in the Arabian Sea},

author = {Wilson-Diaz,D.,Mariano,A.J.,Evans,R.H.,Luther,M.E.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48 },

number = {263},

pages = {1097-1114},

abstract = {Spatial and temporal variability in sea-surface temperature (SST) is analyzed by the method of principal component analysis (PCA). Variability of satellite-derived SST from the NOAA/NASA Advanced Very High Resolution Radiometer (AVHRR) Pathfinder data over the Arabian Sea is compared to the PCA of the mixed-layer temperature fields from two different Indian Ocean models. Climatological model output is compared to Pathfinder's "averaged" year using data from 1987 to 1990. A 5-year analysis with data and model output (from 1985 to 1989) is also done. The first mode in all the studies accounts for 58.2-95.8% of the SST variability, and is identified with the seasonal warming and cooling associated with the Indian Monsoon. The second mode accounts for 20.6-31.1% and corresponds to the radiative heating of the basin. Time series of the basin's mean SST shows that the models lag Pathfinder SST by approximately one month. The climatological models fail to reproduce the SST variability, in both space and time, of the Arabian Sea. The Luther-Ji model, forced by interannual monthly winds, does much better. The main discrepancies are likely due to the models' forcing fields underestimating the strength of the monsoon, and the vertical thermal structure not being adequate to represent the real ocean, especially in upwelling areas.},

keywords = {Arabian Sea, Indian monsoon, Indian Ocean, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Seasonal variability of the colored dissolved organic matter during the 1994-95 NE and SW Monsoons in the Arabian Sea},

author = {Del Castillo,C.E.,Coble,P.G.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47 },

number = {86},

pages = {1563-1579},

abstract = {We performed absorption spectroscopy and fluorescence analyses on water samples collected in the Arabian Sea during the NE and SW Monsoons of 1994-1995. The strong differences in wind regimes between the Monsoons were reflected in the distribution of colored dissolved organic matter (CDOM). Concentrations of fluorescent dissolved organic matter (FDOM) were highest during the SW Monsoon within 100 km of the coast of Oman. In contrast, highest values during the NE Monsoon were found in offshore regions of the Arabian Sea. During the SW Monsoon, surface CDOM and FDOM correlated inversely with temperature, suggesting that upwelled water was the source of the colored and fluorescent material. Vertical profiles showed an inverse relationship between CDOM absorption and temperature, and a decrease in spectral slope with decrease in temperature, suggesting that deeper waters contain higher molecular weight CDOM than shallow waters. Profiles also showed the presence of a highly colored and fluorescent water mass centered at 250 m corresponding to Persian Gulf Water Mass. This water may be a source of colored organic material to overlying water masses.},

keywords = {Arabian Sea, Distribution, Oman, temperature},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Microbial food web structure in the Arabian Sea: a US JGOFS study},

author = {Garrison,D.L.,Gowing,M.M.,Hughes,M.P.,Campbell,L.,Caron,D.A.,Dennett,M.R.,Shalapyonok,A.,Olson,R.J.,Landry,M.R.,Brown,S.L.,Liu,H.-B.,Azam,F.,Steward,G.F.,Ducklow,H.W.,Smith,D.C.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47 },

number = {98},

pages = {1387-1422},

abstract = {One of the main objectives of the Joint Global Ocean Flux Studies (JGOFS) program is to develop an understanding of the factors controlling organic carbon production in the ocean and the time-varying vertical flux of carbon from surface waters (US JGOFS (1990) US JGOFS Planning Report Number 11; Sarmiento and Armstrong (1997) US JGOFS Synthesis and Modeling Project Implementation Plan). A considerable amount of evidence suggests that carbon cycling and the potential for exporting carbon from ocean systems is a function of food web structure. As part of the US JGOFS Arabian Sea Studies, the biomass of planktonic organisms, ranging from heterotrophic bacteria through microplankton-sized organisms, was estimated using a variety of methods including flow cytometry and microscopy. This is a first attempt to combine biomass data from a number of sources, evaluate the structure of the food web, examine changes in food web structure in relation to seasonal or spatial features of the study area, and look for indications of how changing structure affects carbon-cycling processes. Biomass in the upper 100 m of the water column ranged from approximately 1.5 to >5.2 gC m-2. Heterotrophic bacteria (Hbac) made up from 16 and 44% of the biomass; autotrophs comprised 43-64%; and the remainder was made up of nano- and microheterotrophs. Autotrophs and nano- and microheterotrophs showed a general pattern of higher values at coastal stations, with the lowest values offshore. Heterotrophic bacteria (Hbac) showed no significant spatial variations. The Spring Intermonsoon and early NE Monsoon were dominated by autotrophic picoplankton, Prochlorococcus and Synechococcus. The late NE Monsoon and late SW Monsoon periods showed an increase in the larger size fractions of the primary producers. At several stations during the SW Monsoon, autotrophic microplankton, primarily diatoms and Phaeocystis colonies, predominated. Increases in the size of autotrophs were also reflected in increasing sizes of nano- and microheterorophs. The biomass estimates based on cytometry and microscopy are consistent with measurement of pigments, POC and PON. Changes in community structure were assessed using the percent similarity index (PSI) in conjunction with multidimensional scaling (MDS) or single-linkage clustering analysis to show how assemblages differed among cruises and stations. Station clustering reflected environmental heterogeneity, and many of the conspicuous changes could be associated with changes in temperature, salinity and nutrient concentrations. Despite inherent problems in combining data from a variety of sources, the present community biomass estimates were well constrained by bulk measurements such as Chl a, POC and PON, and by comparisons with other quantitative and qualitative studies. The most striking correlation between food web structure and carbon cycling was the dominance of large phytoplankton, primarily diatoms, and the seasonal maxima of mass flux during the SW Monsoon. High nutrient conditions associated with upwelling during the SW Monsoon would explain the predominance of diatoms during this season. The sinking of large, ungrazed diatom cells is one possible explanation for the flux observations, but may not be consistent with the observation of concurrent increases in larger microzooplankton consumers (heterotrophic dinoflagellates and ciliates) and mesozooplankton during this season. Food-web structure during the early NE Monsoon and Intermonsoons suggests carbon cycling by the microbial community predominated.},

keywords = {Arabian Sea, dominance, objectives, salinity, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The fate of upwelled waters in the Great Whirl, August 1995},

author = {Hitchcock,G.L.,Key,E.L.,Masters,J.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {111},

pages = {1605-1621},

abstract = {The Great Whirl is a large, anticyclonic gyre that develops of the northern Somali coast during the Southwest Monsoon. In August 1995 the NOAA Ship Malcolm Baldrige surveyed the seaward edge of the upwelling zone associated with this gyre. The fate of recently upwelled water was followed by mapping surface property distributions along a cool surface feature that extended seaward along the northern edge of the Great Whirl. Surface properties (T, S, and chlorophyll a), surface velocity (ADCP), and XBT and CTD casts were interpreted in relation to the trajectories of three instrumented surface drifters deployed in the feature. Cool surface waters correspond in space to the shoaling of the upper thermocline and offshore advection from the coast. Surface chlorophyll a concentrations decreased from 2 to 3 æg l-1 in the Upwelling zone to 0.5-1.5 æg l-1 in the surface feature and contiguous waters. Maximum surface velocities in the Great Whirl were 250 cm s-1 with velocities >100 cm s-1 along the northern perimeter of the gyre. Decorrelation time-scales for u and v velocity components, and chlorophyll a fluorescence, from the drifters were on the order of 4 to 7 days. These times are comparable to those over which the drifters were ejected from the Great Whirl into the Socotra Gyre. Decorrelation times for sea-surface temperature were somewhat longer (10 days). All three platforms passed between the Somali coast and Socotra within a week of their deployment and then traveled east into the northern Arabian Sea.},

keywords = {Arabian Sea, chlorophyll, Distribution, temperature, thermocline, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Diel vertical migration of zooplankton and mesopelagic fish in the Arabian Sea},

author = {Luo,J.,Ortner,P.B.,Forcucci,D.,Cummings,S.R.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47 },

number = {145},

pages = {1451-1473},

abstract = {Acoustic (153 kHz ADCP and 12 kHz hull-mounted transducers) data and MOCNESS (MOC01 and MOC10) net tow samples collected in the Arabian Sea during the Spring Intermonsoon (April/May) and Southwest Monsoon (August) in 1995 documented substantial diel migrations of fish and zooplankton despite the year-round presence of an oxygen minimum ((0.2 ml l-1 at 125-150 m). Fish and zooplankton layers were distinguished by comparing 12 kHz sonar and 153 kHz ADCP backscatter data, which indicated that the strongly migrating layers were predominantly composed of fishes. Fish vertical migration speeds were independently estimated from the slopes of the volume scattering layers and from the vertical velocity components of the ADCP, yielding average speeds of 4 and 3 cm s-1 and maximum speeds of 13 and 10 cm s-1, respectively. A few migrating zooplankton layers were identified with an average speed of about 2 cm s-1 and maximum speeds as high as 8 cm s-1. Migration depths for both zooplankton and fish differed somewhat amongst stations and appeared to be related to local hydrographic conditions (principally the vertical gradients in DO and water temperature). Zooplankton displacement volumes at individual sites suggested that zooplankton biomass during the Southwest Monsoon could be as much as fivefold greater than during the Spring Intermonsoon. This observation was confirmed for the region in general by first deriving a relationship between ADCP backscatter intensity and daytime zooplankton biomass and then comparing the latter between cruises using daytime ADCP data taken along a 1500 km transect that extended from the coast of Somalia to the center of the northern basin.},

keywords = {acoustic, Arabian Sea, depth, diel, displacement, fish, migration, oxygen minimum, sonar, temperature, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Mezozooplankton production and grazing the Arabian Sea},

author = {Roman,M.,Smith,S.,Wishner,K.,Gowing,M.,Zhang,X.S.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {452},

pages = {1423-1450},

abstract = {Growth rates, grazing and fecal pellet production by mesozooplankton size classes in the surface 200 m are compared over two inshore/offshore transects in the Northern Arabian Sea during different monsoon seasons. We derived these rate parameters from measured biomass and several empirical models that estimate copepod production from temperature, body weight and food availability. The multivariate regression published by Hirst and Sheader (1997, Marine Ecology Progress Series, 154, 155-165) gave the most reasonable rate estimates when compared to direct grazing measurements as well as published data on copepod ingestion and growth rates. In general, zooplankton rate estimates were highest at the inshore stations where phytoplankton production and zooplankton biomass were maximum. Overall cruise means of zooplankton biomass and rate estimates during the early and late NE Monsoon, Spring Inter-monsoon and SW Monsoon were not significantly different. The estimated zooplankton community (all size fractions) growth rate averaged 0.12d(-I) over all stations during the different monsoon seasons. Although smaller zooplankton size fractions grew faster, slower growing > 2 mm zooplankton dominated the zooplankton biomass of the Arabian Sea and this resulted in a lower overall community growth rate. Estimated total carbon (phytoplankton, protozoa and detritus) ingestion averaged 44 mM C m(-2) d(-I), which was approximately 40% of primary production, Expressed as a percentage ofbiomass, we found that zooplankton ingested approximately 400/0 of their body carbon d( -1 ). Zooplankton fecal pellet production averaged 13 mM C m(-2) d(-I) or roughly 12% of primary production. This estimated fecal pellet production was greater than measurements of the export flux during the NE Monsoon and Spring Intermonsoon. However, estimated fecal pellet production was less than measured export flux during the SW Monsoon when sinking phytoplankton likely contributed directly to the export flux. Our data suggest that relative to other ocean basins, the grazing impact of mesozooplankton is significant in the Arabian Sea as a consequence of the high zooplankton biomass, abundance of diatoms, and warm temperatures, which result in high zooplankton metabolic demands and growth rates. The observation that the average zooplankton biomass ( 110 mM C m( -2¯) did not change significantly over the monsoon seasons suggests that zooplankton production (13 mM C m(-2) d(-I)) and zooplankton mortality were similar over the study interval. (C) 2000 Elsevier Science Ltd. All rights reserved.},

keywords = {abundance, Arabian Sea, ecology, marine, mortality, multivariate, temperature, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The Northeast Monsoon's impact on mixing, phytoplankton biomass and nutrient cycling in the Arabian Sea},

author = {Wiggert,J.D.,Jones,B.H.,Dickey,T.D.,Brink,K.H.,Weller,R.A.,Marra,J.,Codispoti,L.A.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {254},

pages = {1353-1385},

abstract = {In the northern Arabian Sea, atmospheric conditions during the Northeast (winter) Monsoon lead to deep convective mixing. Due to the proximity of the permanent pycnocline to the sea surface, this mixing does not penetrate below 125 m. However, a strong nitracline is also present and the deep convection results in significant nitrate flux into the surface waters. This leads to nitrate concentrations over the upper 100 m that exceed 4 æM toward the end of the monsoon. During the 1994/1995 US JGOFS/Arabian Sea expedition, the mean areal gross primary production over two successive Northeast Monsoons was determined to be 1.35 gC/m2/d. Thus, despite the deep penetrative convection, high rates of primary productivity were maintained. An interdisciplinary model was developed to elucidate the biogeochemical processes involved in supporting the elevated productivity. This model consisted of a 1-D mixed-layer model coupled to a set of equations that tracked phytoplankton growth and the concentration of the two major nutrients (nitrate and ammonium). Zooplankton grazing was parameterized by a rate constant determined by shipboard experiments. Model boundary conditions consist of meteorological time-series measured from the surface buoy that was part of the ONR Arabian Sea Experiment's central mooring. Our numerical experiments show that elevated surface evaporation, and the associated salinization of the mixed layer, strongly contributes to the frequency and penetration depth of the observed convective mixing. Cooler surface temperatures, increased nitrate entrainment, reduced water column stratification, and lower near-surface chlorophyll a concentrations all result from this enhanced mixing. The model also captured a dependence on regenerated nitrogen observed in nutrient uptake experiments performed during the Northeast Monsoon. Our numerical experiments also indicate that variability in mean pycnocline depth causes up to a 25% reduction in areal chlorophyll a concentration. We hypothesize that such shifts in pycnocline depth may contribute to the interannual variations in primary production and surface chlorophyll a concentration that have been previously observed in this region.},

keywords = {Arabian Sea, chlorophyll, depth, growth, impact, lead, productivity, surface temperature, temperature, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Fluorescence-based characterization of phycoerythrin-containing cyanobacterial communities in the Arabian Sea during the Northeast and early Southwest Monsoon (1994-1995)},

author = {Wood,A.M.,Lipsen,M.,Coble,P.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {265},

pages = {1769-1790},

abstract = {Scanning fluorescence spectroscopy was used to investigate the spatial and temporal variability in the fluorescence signature of phycoerythrin-containing organisms in the Arabian Sea during the early Northeast and early Southwest Monsoon (1994-1995). Phycoerythrin (PE) emission spectra were relatively invariant among all the samples collected on either cruise; the relatively symmetrical PE emission peaks showed maxima at wavelengths ranging from 563-572 nm. PE excitation spectra always showed either a strong shoulder or a peak at wavelengths absorbed maximally by phycourobilin (PUB) chromophores as well as a peak at wavelengths absorbed maximally by phycoerythrobilin (PEB) chromophores. Thus, the Arabian Sea appears to be different from the Black Sea or Gulf of Maine in that PUB-lacking forms of PE rarely, if ever, dominate the PE signal. Fluorescence excitation signatures differed in the relative excitation of PE emission by wavelengths absorbed by PUB (~495 nm, ExPUB) and bywavelengths absorbed by PEB (~550 nm, ExPEB); these were distinguished by having either very low (~0.6), very high (~1.8), or intermediate ExPUB:ExPEB ratios. The distribution of samples with different PE fluorescence signatures was investigated extensively during the early Southwest Monsoon, and communities characterized by the low ExPUB:ExPEB ratios were closely associated with cooler (24-27§C), fresher (35.7-36.25 psu) water influenced by coastal upwelling. In general, "ambient" surface water of the Arabian Sea during the early Southwest Monsoon was of intermediate temperature (27-29§C) and salinity (36.15-36.4 psu) and showed intermediate or high values for ExPUB :ExPEB. This suggests that the PE fluorescence signature can be used to follow the fate of upwelling-influenced water masses and the populations they transport.  },

keywords = {Arabian Sea, Distribution, Gulf of Maine, population, populations, salinity, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Monsoon climate and Arabian Sea coastal upwelling recorded in massive corals from southern Oman},

author = {Tudhope,A.W.,Lea,D.W.,Shimmield,G.B.,Chilcott,C.P.,Head,S.},

year  = {1996},

date = {1996-01-01},

journal = {Palaios},

volume = {11},

number = {486},

pages = {347-361},

abstract = {Corals living in the coastal waters of southern Oman experience the influence of the seasonally reversing Asian monsoon system.  The objective of the research reported here is to assess the potential for using the skeletal chemistry of these corals to investigate past variability in the monsoon climate.  To this end, 20-year long, monthly resolution geochemical records are presented for cores from two massive Porites  corals, located 20 km apart near Marbat on the Arabian Sea coast of southern Oman.  We consider four aspects of skeletal chemistry: oxygen and carbon isotopic composition, barium content and the nature and occurence of annual fluorescent bands within the coral skeletons.  Coral skeletal ë18O documents variations in sea surface temperature which have regional and basin-wide significance.  In particular, the ë18O of coral skeleton precipitated during the period of the NE monsoon is strongly correlated with annual rainfall anomalies in India, whilst that precipitated during the period of the SW monsoon appears to provide information on variability in the strength of coastal upwelling.   The stable carbon isotope composition and barium content of these particular corals display strong annual cycles, but do not appear to directly record interannual climatic/oceanographic variability.  It is concluded that corals on the coast of southern Oman have great potential to provide high-resolution, century-long records of oceanographic and climatic variability associated with the operation of the monsoon climate system.},

keywords = {Arabian Sea, coral, India, Oman, surface temperature, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Interannual variability in phytoplankton blooms observed in the northwestern Arabian Sea during the southwest monsoon},

author = {Brock,J.C.,McClain,C.R.},

year  = {1992},

date = {1992-01-01},

journal = {Journal of Geophysical Research},

volume = {97},

number = {52},

pages = {733-750},

abstract = {Interannual changes in the strength and seasonal evolution of the 1979 through 1982 surface level southwest monsoon winds have been related to variations in the summer phytoplankton bloom of the northwestern Arabian Sea by synthesis of satellite ocean color remote sensing with analysis of in situ hydrographic and meteorological data sets. The 1979-1981 southwest monsoon phytoplankton blooms in the northwest Arabian Sea peaked during August-September, extended from the Omani coast to about 65øE, and appeared to lag the development of open-sea upwelling by at least 1 month. In all 3 years the bloom was driven by spatially distinct upward nutrient fluxes to the euphotic zone forced by the physical processes of coastal upwelling and offshore Ekman pumping. Coastal upwelling was evident from May through September, yielded the most extreme concentrations of phytoplankton biomass, and along the Omani coast was limited in its impact on upper ocean biological variability to the continental shelf. Ekman pumping stimulated the development of a broad open-ocean component of the southwest monsoon phytoplankton bloom oceanward of the Omani shelf. Phytoplankton biomass on the Omani continental shelf was increased during both the early and late phases of the 1980 southwest monsoon due to stronger coastal upwelling under the most intense southwesterly winds of the four summers investigated. Diminished coastal upwelling during the early phase of the weak 1982 southwest monsoon resulted in a coastal bloom that reached a mean phytoplankton pigment concentration that was 28% of that seen in 1980. The lack of a strong regional northwestern Arabian Sea bloom in late summer 1982 is attributed to the development of persistent, shallow temperature stratification that rendered Ekman pumping less effective in driving upward nutrient fluxes.},

keywords = {Arabian Sea, plankton, productivity, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {A southwest monsoon hydrographic climatology for the northwestern Arabian Sea},

author = {Brock,J.C.,McClain,C.R.,Hay,W.W.},

year  = {1992},

date = {1992-01-01},

journal = {Journal of Geophysical Research},

volume = {97},

number = {337},

pages = {9455-9465},

abstract = {This paper provides a detailed hydrographic climatology for the shallow northwestern Arabian Sea prior to and during the southwest monsoon, presented as multiple-year composite vertical hydrographic sections based on National Oceanographic Data Center historical ocean station data, Temperature and salinity measurements are used to infer the water masses present in the upper 500 m. The hydrographic evolution depicted on bimonthly sections is inferred to result from wind-driven physical processes. In the northwestern Arabian Sea the water mass in the upper 50 m is the Arabian Sea Surface Water. Waters from 50 to 500 m are formed by mixing of Arabian Sea Surface Water with Antarctic and Indonesian intermediate waters. The inflow of Persian Gulf Water does not significantly influence the hydrography of the northwestern Arabian Sea along the Omani coast. Nitrate has a high inverse correlation with temperature and oxygen in the premonsoon thermocline in the depth interval 5(}-150 m. During the southwest monsoon coastal upwelling off Oman and adjacent offshore upward Ekman pumping alter the shallow hydrography.},

keywords = {Antarctic, Arabian Sea, depth, oceanography, Oman, salinity, temperature, thermocline, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Some features of the upwelling off Oman},

author = {Elliott,A.J.,Savidge,G.},

year  = {1990},

date = {1990-01-01},

journal = {Journal of Marine Research},

volume = {48},

number = {365},

pages = {319-333},

abstract = {Hydrographic and ADCP data were collected in the coastal waters of Oman during the 1987 summer monsoon.  the minimum surface temperatures, up to 5§C below ambient offshore values, were found close to the coast and in the vicinity of the Kuria Muria Islands.  Strong surface gradients were observed near Ras al Hadd at the entrance to the Gulf of Oman where the geostrophic surface flow exceeded 1.0m/s.  The alongshore flux in the top 300m of a region extending 100km from the coast was estimated to be 10 x 106 m3/s.  Evidence for an offshore filament of cool water was found in both current and temperature data.},

keywords = {Gulf of Oman, oceanography, Oman, plankton, surface temperature, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {A shore-based survey of upwelling along the coast of Dhofar region, southern Oman},

author = {Savidge,G.,Lennon,J.,Matthews,A.J.},

year  = {1990},

date = {1990-01-01},

journal = {Continental Shelf Research},

volume = {10},

number = {471},

pages = {259-275},

abstract = {A shore-based survey of hydrographic variables along the southern Oman coast between 16ø55'N, 53ø55'E and 170Z3'N, 55ø17.5'E was carried out between August and November 1985 during the southwest monsoon season and the succeeding period marked by the onset of the northeast winds. During the monsoon season strong evidence of upwelling based on temperature and nutrient data was apparent for the eastern half of the survey area which was distinguished by severe coastal relief and a steeply shelving bathymetry. The upwelled water appeared to be advected westwards into the shallower waters of Salalah Bay which comprised the western part of the survey area. Maximum stratification as inferred from increased temperatures and decreased nutrient concentrations was recorded at the western end of Salalah Bay. Marked increases in chlorophyll a were apparent within the Bay at the boundary between the stratified and upwelled water but concentrations were low within the main bodies of the two water types. The upwelling process was discontinuous in time but the intensity of the upwelling was not apparently related to variation in wind strength; only minimal variations in the velocity of the prevailing southwest wind were recorded during the major part of the survey period. Regular diurnal changes of variable amplitude were observed for all properties sampled with the exception of salinity.},

keywords = {bathymetry, chlorophyll, Oman, salinity, survey, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Some details of upwelling off the Somali and Arabian coasts},

author = {Bruce,J.G.},

year  = {1974},

date = {1974-01-01},

journal = {Journal of Marine Research},

volume = {32},

number = {58},

pages = {419-423},

abstract = {Surface temperature and salinity maps from measurements during the period of maximum coastal upwelling in the Arabian Sea are given.  The region of coldest, temperature <14 §C and freshest, salinity ,35.15 % surface water of Ras Mabber (9§ N Somali coast) shifted northeastward during a 10 day period.  Off the Arabian coast the upwelled water was not as cold (minimum 18§C) or fresh (minimum 35.7%) and was found between 16§N and 20§N.},

keywords = {Arabian Sea, oceanography, salinity, surface temperature, temperature, Upwelling},

pubstate = {published},

tppubtype = {article}

}