Characteristics of coastal waters of the western Bay of Bengal during different monsoon seasons

1992 ◽  
Vol 43 (6) ◽  
pp. 1517 ◽  
Author(s):  
A Suryanarayana ◽  
CS Murty ◽  
DP Rao
Keyword(s):  
Fresh Water ◽  
Bay Of Bengal ◽  
Northern Region ◽  
Eastern Coast ◽  
Low Salinity ◽  
The North ◽  
Frontal Zones ◽  
Salinity Water ◽  
Western Bay Of Bengal ◽  
Upwelling Index

Physical characteristics of waters along the eastern coast of India up to offshore distances of 400 km have been investigated during the seasons of the north-easterly and south-westerly monsoons in light of relevant observed meteorological forcings. Analysis of wind data for five years (1980-84) showed high magnitudes of onshore-directed wind-stress impulse in the northern region throughout the year. Under the influence of this impulse, surface waters from offshore move towards the coast and sink along the shore under the direct wind setup. This feature is also indicated by negative values of the upwelling index. Fresh water, discharged through multiple outlets along the coast, mixes within the upper 50 m of the water column and spreads south-westward as a lens of low-salinity water. Further, fresh water advects offshore to distances of about 150 km. The transient, cross-shelf, haline frontal zones observed along the western margin of the Bay of Bengal separate the northern dilute waters from the southern saline waters.

scholarly journals ASIRI: An Ocean–Atmosphere Initiative for Bay of Bengal

2016 ◽  
Vol 97 (10) ◽  
pp. 1859-1884 ◽  
Author(s):  
Hemantha W. Wijesekera ◽  
Emily Shroyer ◽  
Amit Tandon ◽  
M. Ravichandran ◽  
Debasis Sengupta ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Resolution ◽  
Indian Ocean ◽  
Bay Of Bengal ◽  
Regional Scale ◽  
Ocean Dynamics ◽  
Coastal Current ◽  
Northeast Monsoon ◽  
Low Salinity ◽  
Salinity Water

Abstract Air–Sea Interactions in the Northern Indian Ocean (ASIRI) is an international research effort (2013–17) aimed at understanding and quantifying coupled atmosphere–ocean dynamics of the Bay of Bengal (BoB) with relevance to Indian Ocean monsoons. Working collaboratively, more than 20 research institutions are acquiring field observations coupled with operational and high-resolution models to address scientific issues that have stymied the monsoon predictability. ASIRI combines new and mature observational technologies to resolve submesoscale to regional-scale currents and hydrophysical fields. These data reveal BoB’s sharp frontal features, submesoscale variability, low-salinity lenses and filaments, and shallow mixed layers, with relatively weak turbulent mixing. Observed physical features include energetic high-frequency internal waves in the southern BoB, energetic mesoscale and submesoscale features including an intrathermocline eddy in the central BoB, and a high-resolution view of the exchange along the periphery of Sri Lanka, which includes the 100-km-wide East India Coastal Current (EICC) carrying low-salinity water out of the BoB and an adjacent, broad northward flow (∼300 km wide) that carries high-salinity water into BoB during the northeast monsoon. Atmospheric boundary layer (ABL) observations during the decaying phase of the Madden–Julian oscillation (MJO) permit the study of multiscale atmospheric processes associated with non-MJO phenomena and their impacts on the marine boundary layer. Underway analyses that integrate observations and numerical simulations shed light on how air–sea interactions control the ABL and upper-ocean processes.

scholarly journals Wind forcing of salinity anomalies in the Denmark Strait overflow

2011 ◽  
Vol 8 (3) ◽  
pp. 1403-1440 ◽  
Author(s):  
S. Hall ◽  
S. R. Dye ◽  
K. J. Heywood ◽  
M. R. Wadley
Keyword(s):  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Low Salinity ◽  
The North ◽  
East Greenland Current ◽  
Denmark Strait ◽  
Salinity Anomaly ◽  
Salinity Water

Abstract. The overflow of dense water from the Nordic Seas to the North Atlantic through Denmark Strait is an important part of the global thermohaline circulation. The salinity of the overflow plume has been measured by an array of current meters across the continental slope off the coast of Angmagssalik, southeast Greenland since September 1998. During 2004 the salinity of the overflow plume changed dramatically, with the entire width of the array (70 km) freshening between January 2004 and July 2004, with a significant negative salinity anomaly of about 0.06 in May. The event in May represents a fresh anomaly of over 3 standard deviations from the mean since recording began in 1998. We show that the OCCAM 1/12° Ocean General Circulation Model not only reproduces the 2004 freshening event (r=0.96, p<0.01), but also correlates well with salinity observations over a previous 6 year period (r=0.54, p<0.01). Consequently the physical processes causing the 2004 anomaly and prior variability in salinity are investigated using the model output. Our results reject the hypotheses that the anomaly is caused by processes occurring between the overflow sill and the moorings, or by an increase in upstream net freshwater input. Instead, we show that the 2004 salinity anomaly is caused by an increase in volume flux of low salinity water, with a potential density greater than 27.60 kg m−3, flowing towards the Denmark Strait sill in the East Greenland Current. This is caused by an increase of southward wind stress upstream of the sill at around 75° N 20° W four and a half months earlier, and an associated spin-up of the Greenland Sea Gyre.

scholarly journals The shelf and coastal waters off southern Brazil

1961 ◽  
Vol 11 (2) ◽  
pp. 101-112 ◽  
Author(s):  
Ingvar Emílsson
Keyword(s):  
Surface Waters ◽  
Maximum Velocity ◽  
Water Layer ◽  
Subtropical Zone ◽  
Low Salinity ◽  
The North ◽  
Tropical Water ◽  
Brazil Current ◽  
Salinity Water ◽  
Current Flows

The data collected on three oceanographic cruises undertaken in 1956 indicate that the main branch of the Brazil Current flows southwards along the continental slope, where it reaches maximum velocity, and further, that a well defined limit is found between the warm and saline tropical water from the north and that situated over the central part of the shelf. This is especially the case during the summer months (October-March). Below the Brazil Current a water layer of lower salinity and temperature is found. This water mass is formed near the western extremity of the Subtropical Convergence where it sinks and flows northwards to reappear near or at the surface in an area situated between the lighter, south-flowing, tropical water, and the coastal water. Such a distribution of density across the Current is to be expected in view of the dynamics of ocean currents. There are, however, evidences which indicate the occurrence of upwelling from moderate depths, in particular near Cabo Frio where the prevailing winds from NE drive the surface waters offshore. It is further suggested that the upwelling is maintained by a thermohaline mechanism as the density of the cold and low salinity water is decreased by heating from solar radiation. In order to maintain dynamic stability, the heated water must consequently flow out of the area and be replaced by water from below which in turn suffers the same decrease of density, and so on. Such mechanism might, together with prevailing winds, be responsible for permanent or periodic upwelling near other regions in the tropical and subtropical zone of the oceans where salinity decreases with depth.

scholarly journals Biometry, length-weight and length-length relationships of flathead sillago Sillaginopsis panijus (Hamilton, 1822) (Perciformes: Sillaginidae) from the north-western Bay of Bengal

2020 ◽  
Vol 67 (3) ◽  
Author(s):  
Suraj Kumar Pradhan ◽  
Subal Kumar Roul ◽  
Shubhadeep Ghosh ◽  
Pritam Tripathy ◽  
A. K. Jaiswar ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Fork Length ◽  
Mesh Size ◽  
Population Based ◽  
Total Length ◽  
The North ◽  
Baseline Information ◽  
Eye Diameter ◽  
Western Bay Of Bengal ◽  
North Western

Biometry, length-weight relationships (LWRs) and length-length relationships (LLRs) of Sillaginopsis panijus (Hamilton, 1822) were investigated in the Indian coast of north-western Bay of Bengal. Altogether 622 specimens were collected between August 2018 and September 2019 from landings by trawls (30-35 mm mesh size), gillnets (15-55 mm mesh size) and shore seines (7-15 mm bag mesh size). The total length and weight of the specimens ranged from 7.8-40.3 cm and 2.9-506 g, respectively. The LWR established was W=0.0048 L3.059 for males, W=0.0032 L3.185 for females and W=0.0047 L3.0645 for indeterminates, indicating positive allometric growth pattern. All the LWRs were highly significant (p<0.001, r2≥0.977). The highest coefficient of correlation (r) was observed for total length against fork length (0.999) and lowest for head length against eye diameter (0.951). The fin formula was expressed as D1 X, D2 I + 24-28, P 17-22, V I + 5, A II + 25-27, GR 2-3/6-9. The study provides the first detailed account of the biometric relationships of S. panijus in the north-western Bay of Bengal, which can be used as baseline information for subsequent biological and population based studies in the region.

scholarly journals Contrasting Response of the Eastern and Western North Atlantic Circulation to an Episodic Climate Event*

2011 ◽  
Vol 41 (9) ◽  
pp. 1630-1638 ◽  
Author(s):  
Ayan H. Chaudhuri ◽  
Avijit Gangopadhyay ◽  
James J. Bisagni
Keyword(s):  
North Atlantic ◽  
High Salinity ◽  
Scale Model ◽  
High Salinity Water ◽  
Low Salinity ◽  
The North ◽  
Basin Scale ◽  
Salinity Water ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Regional observational studies in the North Atlantic have noted significant hydrographical shifts in 1997–98 because of the episodic drop in the North Atlantic oscillation (NAO) during 1996. Investigation using a basin-scale model finds that, although the western North Atlantic (WNA) witnessed unusually low-salinity water by 1997, the eastern North Atlantic (ENA) simultaneously evidenced intrusions of high-salinity water at intermediate depths. This study shows that a major source of high salinity in the ENA is from the northward penetration of Mediterranean Outflow Water (MOW) that occurred concurrently with a westward shift of the subpolar front. The authors confirm that the low-salinity intrusion in the WNA is from enhanced Labrador Current flow. Results from climatological high- and low-NAO simulations suggest that the NAO-induced circulation changes that occurred in 1997–98 are a characteristic North Atlantic basin response to different forcing conditions during characteristic high- and low-NAO periods.

Hydrography and biogeochemistry of the north western Bay of Bengal and the north eastern Arabian Sea during winter monsoon

2008 ◽  
Vol 73 (1-2) ◽  
pp. 76-86 ◽  
Author(s):  
K.K. Balachandran ◽  
C.M. Laluraj ◽  
R. Jyothibabu ◽  
N.V. Madhu ◽  
K.R. Muraleedharan ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Arabian Sea ◽  
Winter Monsoon ◽  
The North ◽  
North Eastern ◽  
Eastern Arabian Sea ◽  
Western Bay Of Bengal ◽  
North Western
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