Coastal upwelling in the San Jorge Gulf (Southwestern Atlantic) from remote sensing, modelling and hydrographic data

2020 ◽  
Vol 245 ◽  
pp. 106919 ◽  
Author(s):  
Juan P. Pisoni ◽  
Andrés L. Rivas ◽  
Mariano H. Tonini
Keyword(s):  
Remote Sensing ◽  
Coastal Upwelling ◽  
Southwestern Atlantic ◽  
Hydrographic Data

The El Nino-Southern Oscillation in south-eastern Australian waters

1991 ◽  
Vol 42 (3) ◽  
pp. 263 ◽  
Author(s):  
WW Hsieh ◽  
BV Hamon
Keyword(s):  
Sea Level ◽  
Coastal Upwelling ◽  
Southern Oscillation ◽  
Geostrophic Wind ◽  
Air Pressure ◽  
Ekman Transport ◽  
Hydrographic Data ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

Using four decades of hydrographic data collected off the coast near Sydney, New South Wales, and sea-level data at Sydney, we studied the interannual variability in south-eastern Australian shelf waters. The first two empirical orthogonal function (EOF) modes of the band-pass-filtered 50-m-depth hydrographic data (temperature, T; salinity, S; nitrate, N; inorganic phosphate, P; and oxygen, O) and the sea level (SL) and adjusted sea level (ASL) data accounted respectively for 51 and 27% of the total variance. Both modes were significantly correlated with the Southern Oscillation Index (SOI). The first mode, with T, S, O and ASL varying in opposition to N and P, represented the internal or baroclinic response, associated with vertical displacements of the isopycnals. The second mode, with large in-phase fluctuations in SL and ASL but small changes in the hydrographic variables, represented mainly the external or barotropic response during the El Niiio-Southern Oscillation (ENSO). Three-year composites centred around seven ENSO warm episodes revealed that T, S, O and ASL were generally low and N, P, SL and SO1 were high in the year before each ENSO warm episode, but the former group rose while the latter group dropped in the year of the warm episode. The changes in the hydrographic variables at 50 m depth were consistent with relatively shallow isopycnals in the year before the ENSO warm episode, followed by a deepening of the isopycnals during the warm episode. Estimates of this downward displacement of isopycnals, as determined from T, N, P and O, were in the range 7-10 m. The geostrophic wind arising from the pressure fluctuations during ENSO is proposed as a probable cause for the vertical displacement of the isopycnals. In the year before the warm episode, the low air pressure over Australia would produce a clockwise geostrophic wind around south-eastern Australia, generating offshore Ekman transport and coastal upwelling. During the warm episode, air pressure over Australia rises, the geostrophic wind reverses, and downward movement of the isopycnals would occur off south-eastern Australia.

Assessing the performance of a multi-nested ocean circulation model using satellite remote sensing and in situ observations

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Shiliang Shan ◽  
Jinyu Sheng ◽  
Kyoko Ohashi ◽  
Mathieu Dever
Keyword(s):  
Remote Sensing ◽  
Nova Scotia ◽  
Ocean Circulation ◽  
Satellite Remote Sensing ◽  
Coastal Upwelling ◽  
Circulation Model ◽  
Tidal Mixing ◽  
Scotian Shelf ◽  
Ocean Circulation Model

This study presents a multi-nested ocean circulation model developed recently for the central Scotian Shelf. The model consists of four submodels downscaling from the eastern Canadian Shelf to the central Scotian Shelf. The model is driven by tides, river discharges, and atmospheric forcing. The model results are validated against observations, including satellite remote sensing data from GHRSST and Aquarius and in situ measurements taken by tide gauges, a marine buoy, ADCPs and CTDs. The ocean circulation model is able to capture variations of sea level, hydrography and the Nova Scotia Current on timescales of days to seasons over the central Scotian Shelf. Model results are used in a process study to examine the effect of tidal mixing and wind-driven coastal upwelling in the formation of cold surface waters along the coast of Nova Scotia.

Investigation of hydrogen sulphide eruptions along the Namibian coastline using different remote sensing systems

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Thomas Ohde
Keyword(s):  
Remote Sensing ◽  
Hydrogen Sulphide ◽  
Coastal Upwelling ◽  
Temporal Distribution ◽  
Dust Deposition ◽  
Ocean Colour ◽  
The North ◽  
Microwave Scatterometer ◽  
Westerly Direction ◽  
Remote Sensing Techniques

AbstractHydrogen sulphide eruptions with their typical turquoise discolorations at the water surface are a unique phenomenon along the Namibian coastline. The remote sensing techniques of ocean colour sensors and microwave scatterometers were used for the investigation of such events. The studies with ocean colour sensors showed that the turquoise discolorations near the Namibian coast were neither linked to dust deposition into the water column by desert storms nor to the reflection of bright material in shallow water areas. In addition, other coloured marine events like algae blooms and river outflows were differentiable from the hydrogen sulphide eruptions by their special optical properties. Quasi-true colour images and spectral identification methods were utilised to monitor and investigate the spatial and temporal distribution of sulphide events. In the past years, they were sometimes and locally limited discovered. Newest remote sensing observations including our own investigations have established that the occurrence of sulphide events is more frequent and longer lasting. The north-westerly direction of propagation and their velocity between 12 cm s-1 and 15 cm s1 were derived from an event on 14 April 2004. Lastly, the microwave scatterometer remote sensing was applied to investigate the relation of sulphide events to oceanographic conditions. The events from May 2004 were clearly related to strong coastal upwelling.

scholarly journals Prediction of Coastal Upwelling Using Remote Sensing

IJARCCE ◽  
2016 ◽  
Vol 5 (1) ◽  
pp. 43-47
Author(s):  
Priya R ◽  
Ranjani R ◽  
Thamizharasi M
Keyword(s):  
Remote Sensing ◽  
Coastal Upwelling

scholarly journals Variability of Net Primary Productivity and Associated Biophysical Drivers in Bahía de La Paz (Mexico)

2021 ◽  
Vol 13 (9) ◽  
pp. 1644
Author(s):  
Rafael Cervantes-Duarte ◽  
Eduardo González-Rodríguez ◽  
René Funes-Rodríguez ◽  
Alejandro Ramos-Rodríguez  ◽  
María Yesenia Torres-Hernández ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Remote Sensing Data ◽  
In Situ Measurements ◽  
Hydrographic Data ◽  
La Paz ◽  
Sensing Data ◽  
Spatio Temporal

The use of information of net primary productivity (NPP) from remote ocean color sensors is increasingly common in marine sciences. The resulting information has been used to explain variations in productivity at different spatio-temporal scales and in the presence of climate phenomena, such as the El Niño Southern Oscillation, and global warming. Satellite remote sensing data were analyzed in Bahía de La Paz (BLP), Mexico, to determine the spatio-temporal variation in NPP. In addition, in situ hydrographic data were obtained to characterize the water properties in the bay. The satellite data agree with in situ measurements, validating the satellite observations over this region. The NPP generally presented seasonal variation with maximum values in winter-spring and minimum values in summer–autumn. The variance explained by NPP from the measured variables was ranked as Chl-a < DEN < SST < PAR < WSC. The highest NPP values generally occurred when subtropical subsurface (SsStW) water was relatively shallow. Due to divergence and mixing processes, this water provided nutrients to the euphotic zone, and consequently an increase in NPP and changes in plankton biomass were observed. The annual trends of the variation in hydrographic data with respect to that of remote sensing data were similar; however, it is necessary to increase the number of data validation studies. The remote sensing and in situ measurements allowed for the main biophysical variables that modulate NPP in different time scales to be identified. The satellite-derived NPP data classifies the BLP as a high productivity zone with 432 g C m−2 year−1. The use of satellite NPP data is satisfactory and should be incorporated into marine primary productivity studies.

scholarly journals Pseudo-nitzschia Blooms in a Coastal Upwelling System: Remote Sensing Detection, Toxicity and Environmental Variables

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1954 ◽  
Author(s):  
Jesus M. Torres Palenzuela ◽  
Luis González Vilas ◽  
Francisco M. Bellas ◽  
Elina Garet ◽  
África González-Fernández ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Domoic Acid ◽  
Coastal Upwelling ◽  
Empirical Models ◽  
Full Resolution ◽  
Shellfish Farming ◽  
Sensing Model ◽  
Key Variables

The NW coast of the Iberian Peninsula is dominated by extensive shellfish farming, which places this region as a world leader in mussel production. Harmful algal blooms in the area frequent lead to lengthy harvesting closures threatening food security. This study developed a framework for the detection of Pseudo-nitzschia blooms in the Galician rias from satellite data (MERIS full-resolution images) and identified key variables that affect their abundance and toxicity. Two events of toxin-containing Pseudo-nitzschia were detected (up to 2.5 μg L−1 pDA) in the area. This study suggests that even moderate densities of Pseudo-nitzschia in this area might indicate high toxin content. Empirical models for particulate domoic acid (pDA) were developed based on MERIS FR data. The resulting remote-sensing model, including MERIS bands centered around 510, 560, and 620 nm explain 73% of the pDA variance (R2 = 0.73, p < 0.001). The results show that higher salinity values and lower Si(OH)4/N ratios favour higher Pseudo-nitzschia spp. abundances. High pDA values seem to be associated with relatively high PO43, low NO3− concentrations, and low Si(OH)4/N. While MERIS FR data and regionally specific algorithms can be useful for detecting Pseudo-nitzschia blooms, nutrient relationships are crucial for predicting the toxicity of these blooms.

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