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Variability of River Plume Signature Determined Using Satellite Images  [PDF]
A. Jabbar,T. Lihan,M.A. Mustapha,Z.A. Rahman
Journal of Applied Sciences , 2013,
Abstract: Estuarine outflow associated with suspended matter concentrations and pollutants have a major impact on marine ecosystems. Understanding the dynamics and dispersal pattern of suspended matter from river water are important for management of coastal water quality and biological productivity. This study aimed to determine the variability of Pahang River plume signature at the coastal area. One km spatial-resolution normalized water-leaving radiance, (nLw 551) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua satellite were analyzed from the period of 2005-2010. The plume spectral signature estimated of the backscattering coefficient nLw 551 (proxy for suspended matter) was strongly correlated with the amount of monthly average rainfall over the study period. The plume signature distributions during 2005-2010 based on nLw 551 was highly variable. During northeast monsoon, the plume tends to propagate to the south and shows the strongest plume signature of nLw 551 value (>2.0 mW cm-2 m-1 sr-1) meanwhile during southwest monsoon the plume dispersion to the north and exhibit weakest plume signature value (<1.5 mW cm-2 m-1 sr-1). The variability of plume signature was determined by the backscattering characteristics of surface waters in the region of the river mouth as a result of rainfall, wind stress and surface current event.
Nutrient and phytoplankton biomass in the Amazon River shelf waters
Santos, Maria L.S.;Muniz, Kátia;Barros-Neto, Benício;Araujo, Moacyr;
Anais da Academia Brasileira de Ciências , 2008, DOI: 10.1590/S0001-37652008000400011
Abstract: the amazon river estuary is notable at the amazon continental shelf, where the presence of the large amount of water originating from the amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. even so, the presence of oceanic waters in the shelf area was significant. dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. the chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. the anomalous amounts of inorganic dissolved nitrogen showed more removal than addition. the simulations with the bidimensional maac-2d model confirmed that high nutrient waters are displaced northwest-ward (two cores at 2.5on-50ow and 4on-51ow) by the stronger nbc during falling river discharge. during high river flow period these nutrient-rich lenses are distributed around 0.5on-48.5ow as well as along the shallow amazonian shelf (20m-50m depth, 1on-3.5on), as a result of the spreading of amazon freshwater outflow.
Observa??es hidrológicas e resultados de modelagem no espalhamento sazonal e espacial da pluma de água Amaz?nica
Silva, Alex Costa da;Santos, Maria de Lourdes Souza;Araujo, Moacyr Cunha;Bourlès, Bernard;
Acta Amazonica , 2009, DOI: 10.1590/S0044-59672009000200014
Abstract: in this study, we present surface synoptic data collected during four oceanographic cruises undertaken in march-april 1995, october-november 1997, april-may 1999 and august-september 2001 in the brazilian program “revizee/score-no” and a combination of model results (1/6 deg.). the emphasis of this paper is to point out the monthly changes on the spreading of the amazon plume over the external amazon shelf area and the eastern region of the amazon river. hydrographic data and model results demonstrated that during march-may, the amazon plume moved southwestward along the northern coast of brazil, decreasing during august-september; but this was not observed during october-november. model results revealed ring signatures shedding from the north brazil current (nbc). results also showed that during august the amazon plume encircling the nbc retroflection was around 7o n.
REMOTE SENSING OF THE SEDIMENTATION PLUME OF THE RIVER SAN JUAN
Ballestero,Daniel;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000200004
Abstract: the river san juan (rsj), in the border between nicaragua and costa rica, is one the major rivers in central america and drains the largest basin in the region (38570 km2) in terms of volume. extending from lago cicibolca to the caribbean sea, the rsj is an important source of freshwater, sediments, nutrients and pollutants to the continental shelf. ecosystems degradation, contamination of water bodies and overexploitation of natural resources, particularly deforestation in the southern part of the basin, modified and incremented sedimentation processes in the basin and the coastal margin during the last few decades. advanced very high resolution radiometer and sea-viewing wide field-of-view sensor data, together with in-situ ctd, current meter, turbidity sensor and water sampling for chemical analysis data are used to study, for the first time, the spatial and temporal variability of the plume of the rsj and the coastal zone under its influence. an atmospheric correction has been implemented in order to obtain water reflectance from the avhrr channels 1 and 2. results from the above satellite and in-situ observations are presented
REMOTE SENSING OF THE SEDIMENTATION PLUME OF THE RIVER SAN JUAN
Daniel Ballestero
Gayana (Concepción) , 2004,
Abstract: The River San Juan (RSJ), in the border between Nicaragua and Costa Rica, is one the major rivers in Central America and drains the largest basin in the region (38570 km2) in terms of volume. Extending from Lago Cicibolca to the Caribbean Sea, the RSJ is an important source of freshwater, sediments, nutrients and pollutants to the continental shelf. Ecosystems degradation, contamination of water bodies and overexploitation of natural resources, particularly deforestation in the southern part of the basin, modified and incremented sedimentation processes in the basin and the coastal margin during the last few decades. Advanced Very High Resolution Radiometer and Sea-viewing Wide Field-of-view Sensor data, together with in-situ CTD, current meter, turbidity sensor and water sampling for chemical analysis data are used to study, for the first time, the spatial and temporal variability of the plume of the RSJ and the coastal zone under its influence. An atmospheric correction has been implemented in order to obtain water reflectance from the AVHRR channels 1 and 2. Results from the above satellite and in-situ observations are presented
Influence of River Plume on Variability of Chlorophyll a Concentration using Satellite Images  [PDF]
T. Lihan,M.A. Mustapha,S.A. Rahim,S. Saitoh
Journal of Applied Sciences , 2011,
Abstract: Freshwater discharge from rivers into the ocean is an important element of the dynamics in coastal areas. River discharge from land that includes chlorophyll a, nutrients, sediments and pollutants have been identified as one of the major causes of deterioration of the coastal water. The objective of this study was to examine the relationship between river discharge and variability of chlorophyll a concentration in plume area using satellite imagery. Satellite ocean color and Sea Surface Temperature (SST) imagery were used to present the synoptic quantification of chlorophyll a variability on seasonal and interannual timescales for the plume area of Tokachi River, Japan. Five years (1998 to 2002) of SeaWiFS local area coverage, AVHRR imagery and surface wind were analyzed using default NASA coefficients and community-standard algorithms as implemented by SeaDAS. The chlorophyll a climatology seasonal pattern showed seasonal cycles, first peak in spring and second peak in late summer to early autumn. Elevated chlorophyll a concentration demonstrates seasonal cycles and interannual variability are present around plume area associated with variation of river discharge. Elevated chlorophyll a concentration in offshore area was seen to be influenced by low sea surface temperature and wind stress.
Chemical characterization and relevant geochemical aspects of suspended organic matter on the Amazon river delta  [PDF]
Simone Baía Pereira,Waterloo Napole?o de Lima,Maamar El-Robrini
Boletim do Museu Paraense Emílio Goeldi : Ciências Naturais , 2006,
Abstract: Characteristics of geoenvironment of the Amazon river have been described by several researchers, where the appreciable extension of its drainage basin, the influence of the forest, erosion, seasonality, the considerable pluviometric index, the material transported in suspension and the notable discharge flown by the Atlantic ocean have been emphasized. This study, accomplished in Alive Resources of the exclusive Economic Zone Program (REVIZEE) ambit, in sediments samples collected in coastal waters of the Atlantic ocean under influence of the Amazon river, during the 2nd scientific cruise of the North Operation II, on ship-board Antares oceanographic, proceeds chemical characterization and it discusses important geochemistry aspects of the organic matter from bottom sediments and in suspension in the mouth of the great river. It was observed that the high concentrations of the suspended matter (maxim in 2300 mg.L-1) are met in collection points close to the coast, tending to zero off shore. The variation of the content of the organic matter associated to that suspended matter is relatively restricted (minimal in 1,91% and maximum in 3,53%). The identification of the chemical nature of the organic matter indicates the occurrence of humic material, probably associated to the drainage of characteristic amazon soils, as the podzols and the latosols, material transported by Amazon River as far as coastal waters. The chemical characterization of the humic material identified groups methylene (directly related with aliphatic hydrocarbons), of groups C=O (of carboxylate and/or ketones) and of bands owed the associated clayminerals. The content of organic matter was always shown below 3,6%, exhibiting reason values C/N varying from 9,64 (suspended matter) to 68,3 (bottom sediments), in agreement with the largest or smaller influence of nitrogen organic compounds and/or largest or smaller period of maturation of the organic material. In samples presenting higher reasons C/N; an origin should be waited in that dominate products of the decomposition of cellulose and/or which are associated to a period of more recent maturation. The content of present phosphate in the sediment, varying from 0,06% to 0,78% (expressed in mg.L-1 of P), suggests marine influences of the ambient (perhaps involving contributions of P biogenic), through the resuspension of sediments, being common in estuarines environments.
Rapid shifts of the river plume pathway off the Huanghe (Yellow) River mouth in response to water-sediment regulation scheme in 2005
Houjie Wang,Zuosheng Yang,Naishuang Bi,Haidong Li
Chinese Science Bulletin , 2005, DOI: 10.1360/982005-1196
Abstract: Freshwater plume represents a key passage for the river to deliver sediment to the coastal ocean. A water-sediment regulation scheme was implemented for the Huanghe River in 2005; in order to examine the effect of such an activity on the river plume dynamics, three cruises were carried out off the Huanghe River mouth. The preliminary results of the in-situ measurements suggested that the plume pathway shifted rapidly during the period of less than twenty days, which was confirmed by satellite remote sensing data in the same period. The rapid shifts were resulted from intensive interactions between river discharge and the varying bathymetry in the river mouth area. A large amount of river sediment was delivered to the coastal region during this period and mostly deposited in the mouth bar area due to jet-flow deceleration, forming a cluster of mouth bars across the river mouth, which caused the rapid shifts of the plume pathway.
ANALYSIS OF SPACE-TIME VARIABILITY OF THE PLATA RIVER PLUME
Piola,Alberto R.; Romero,Silvia I.;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000300030
Abstract: satellite ocean colour data from the sea-viewing wide field-of-view sensor are analyzed to monitor the space-time variability of the plata river plume over the continental shelf and slope. seawifs chlorophyll-a (csat) product is used to understand the nature of changes in the colour of waters and how this relates to variations in wind direction and river outflow. we use a 5-year data set (1998-2002) of global area coverage monthly mean composites. the analysis of csat data reveals strong seasonal variability over the continental shelf with maximum northeastward penetrations in the austral winter (june to august). the plume may reach ~27s, about 1000 km northeast of the plata estuary. in summer the plume is confined to south of 32°s and the plata waters are frequently exported to the open ocean through the brazil/malvinas confluence. this seasonal shift is similar to the variation of surface salinity observed in historical hydrographic data and is presumably associated to the variable influence of the along-shore wind stress. interannually, 2002 showed the maximum northeastward penetration and the strongest anomalies (6mg/m3). from late 1999 to early 2000, a strong negative csat anomaly (<6mg/m3) within the estuary could be linked to a period of very low plata outflow (<12,000m3/seg). results suggest that csat geophysical product is a good indicator of the presence of the plata diluted waters. other case ii ocean colour products are being explored (cdom)
ANALYSIS OF SPACE-TIME VARIABILITY OF THE PLATA RIVER PLUME  [cached]
Alberto R. Piola,Silvia I. Romero
Gayana (Concepción) , 2004,
Abstract: Satellite ocean colour data from the Sea-Viewing Wide Field-of-View Sensor are analyzed to monitor the space-time variability of the Plata river plume over the continental shelf and slope. SeaWiFS Chlorophyll-a (CSAT) product is used to understand the nature of changes in the colour of waters and how this relates to variations in wind direction and river outflow. We use a 5-year data set (1998-2002) of Global Area Coverage monthly mean composites. The analysis of CSAT data reveals strong seasonal variability over the continental shelf with maximum northeastward penetrations in the austral winter (June to August). The plume may reach ~27S, about 1000 km northeast of the Plata estuary. In summer the plume is confined to south of 32°S and the Plata waters are frequently exported to the open ocean through the Brazil/Malvinas Confluence. This seasonal shift is similar to the variation of surface salinity observed in historical hydrographic data and is presumably associated to the variable influence of the along-shore wind stress. Interannually, 2002 showed the maximum northeastward penetration and the strongest anomalies (6mg/m3). From late 1999 to early 2000, a strong negative CSAT anomaly (<6mg/m3) within the estuary could be linked to a period of very low Plata outflow (<12,000m3/seg). Results suggest that CSAT geophysical product is a good indicator of the presence of the Plata diluted waters. Other Case II ocean colour products are being explored (CDOM)
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