On the observability of the fortnightly cycle of the Tagus estuary turbid plume using MODIS ocean colour images

Valente, André; Silva, José C. B. da

doi:10.1016/j.jmarsys.2008.08.008

Cited by 56 publications

(36 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another puzzling feature is that, unlike typical observations from other marginal seas, the ISW sea surface manifestations appear quite far from the nearest continental shelves -as far as 500 km in comparison with distances of approximately 100 km in other regions (e.g. in the Mozambique Channel; see da Silva et al, 2009). These and other results are to be discussed in the next section.…”

Section: Sar Imagery Analysismentioning

confidence: 80%

“…the Mascarene Ridge; see da Silva et al, 2011), these observations are not clustered around some particular phase of the floodebb tidal cycle (the latter effect being a consequence of sunsynchronous orbits; e.g. Valente and da Silva et al, 2009 Table 1 (each corresponding to an image acquisition), using the tidal constituents listed in the bottom-left corner, and computed correspondingly at locations A and B (represented by white and black circles, respectively). Note that, for a meaningful comparison, the time running in the horizontal direction is with reference to the transition between high tide and low tide (i.e.…”

Section: Sar Imagery Analysismentioning

confidence: 93%

“…Both new and unidentified IW hotspots, as well as previously studied regions, have benefited from satellite views, frequently providing new and deeper insights into their generation, propagation and dissipation mechanisms (e.g. Zhao et al, 2004;Vlasenko and Alpers, 2005;Azevedo et al, 2006;Magalhaes et al, 2012) -see also http://jmagalhae0. wix.com/internal-waves-.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

et al. 2016

View full text Add to dashboard Cite

Abstract. Synthetic aperture radar (SAR) imagery from the Amazon shelf break region in the tropical west Atlantic reveals for the first time the two-dimensional horizontal structure of an intense Internal Solitary Wave (ISW) field, whose first surface manifestations are detected several hundred kilometres away from the nearest forcing bathymetry. Composite maps and an energy budget analysis (provided from the Hybrid Coordinate Ocean Model -HYCOM) help to identify two major ISW pathways emanating from the steep slopes of a small promontory (or headland) near 44 • W and 0 • N, which are seen to extend for over 500 km into the open ocean. Further analysis in the SAR reveals propagation speeds above 3 m s −1 , which are amongst the fastest ever recorded. The main characteristics of the ISWs are further discussed based on a statistical analysis, and seasonal variability is found for one of the ISW sources. This seasonal variability is discussed in light of the North Equatorial Counter Current. The remote appearance of the ISW sea surface manifestations is explained by a late disintegration of the internal tide (IT), which is further investigated based on the SAR data and climatological monthly means (for stratification and currents). Acknowledging the possibility of a late disintegration of the IT may help explain the remote-sensing views of other ISWs in the world's oceans.

show abstract

Section: Sar Imagery Analysismentioning

confidence: 80%

Section: Sar Imagery Analysismentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

et al. 2016

View full text Add to dashboard Cite

show abstract

“…For each scene, the plume extension was delimited by thresholding of the nLw555 image. The threshold between "plume boundary" and coastal waters was defined as 1.3 mW/ cm 2 μm sr (Otero & Siegel, 2004;Valente & da Silva, 2009). Visual examination of a subset of images suggested that this value adequately defined the river plume (data not shown).…”

Section: Satellite Imagerymentioning

confidence: 99%

The influence of the Guadalquivir river on spatio-temporal variability in the pelagic ecosystem of the eastern Gulf of Cádiz

Caballero

Morris²,

Pietro³

et al. 2014

Medit. Mar. Sci.

View full text Add to dashboard Cite

This study examines the spatio-temporal variability of the turbidity plume and phytoplankton biomass (in terms of chlorophyll) in the marine region influenced by the Guadalquivir estuary using ocean colour images over a period of 11 years (2003-2013). The area of the turbidity plume was calculated using water-leaving radiance at 555 nm (nLw555). Climatologic and monthly averages showed recurrent high nLw555 levels in winter and high chlorophyll in spring. Similar variability was confirmed by Empirical Orthogonal Function (EOF) analysis of 8-day composite images, illustrating the existence of different regions with similar behavior. The first EOF mode explained 60.7% and 31% of the variability in nLw555 and chlorophyll, respectively, and was associated with enhanced Total Suspended Solids (TSS) in autumn-winter and phytoplankton blooms in winter-spring periods. The results confirmed that the development of the turbidity plume and subsequent phytoplankton blooms were strongly regulated by river discharges and precipitation. Indeed, interannual variation in nLw555 was consistent with changes in the large-scale climate index, the North Atlantic Oscillation, a proxy for regional rainfall patterns. In the case of phytoplankton biomass, the second EOF mode revealed differentiation between offshore and nearshore areas, the latter characterized by delayed development of phytoplankton bloom due to light limitation by high TSS. This suggests that the stability of the water column, via its influence on phytoplankton light-limitation, influenced also the timing and magnitude of phytoplankton bloom events. The dynamic of the Guadalquivir estuary turbidity plume is a crucial factor for the pelagic ecosystem of the Eastern Gulf of Cadiz, governing phytoplankton productivity.

show abstract

“…However, thermal fronts are occasionally non-collocated with fronts in other properties (e.g., nutrients and salinity) [15][16][17]. Ocean color images, in contrast to thermal satellite data, can provide a more direct and accurate indication of the density gradients associated with physical processes [7,8,18,19], and can characterize seasonal and inter-annual variability [20][21][22][23]. Moreover, biophysical interaction and multi-scale physical processes (e.g., phytoplankton bloom, mesoscale eddies) are successfully visualized by combining thermal and ocean color fronts into a single map using visible and thermal satellite observations (e.g., Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), The Advanced Very High Resolution Radiometer (AVHRR), and Moderate Resolution Imaging Spectroradiometer (MODIS)) [8,[24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Diurnal Variability of Turbidity Fronts Observed by Geostationary Satellite Ocean Color Remote Sensing

Pan

et al. 2016

Remote Sensing

View full text Add to dashboard Cite

Abstract:Monitoring front dynamics is essential for studying the ocean's physical and biogeochemical processes. However, the diurnal displacement of fronts remains unclear because of limited in situ observations. Using the hourly satellite imageries from the Geostationary Ocean Color Imager (GOCI) with a spatial resolution of 500 m, we investigated the diurnal displacement of turbidity fronts in both the northern Jiangsu shoal water (NJSW) and the southwestern Korean coastal water (SKCW) in the Yellow Sea (YS). The hourly turbidity fronts were retrieved from the GOCI-derived total suspended matter using the entropy-based algorithm. The results showed that the entropy-based algorithm could provide fine structure and clearly temporal evolution of turbidity fronts. Moreover, the diurnal displacement of turbidity fronts in NJSW can be up to 10.3 km in response to the onshore-offshore movements of tidal currents, much larger than it is in SKCW (around 4.7 km). The discrepancy between NJSW and SKCW are mainly caused by tidal current direction relative to the coastlines. Our results revealed the significant diurnal displacement of turbidity fronts, and highlighted the feasibility of using geostationary ocean color remote sensing technique to monitor the short-term frontal variability, which may contribute to understanding of the sediment dynamics and the coupling physical-biogeochemical processes.

show abstract

On the observability of the fortnightly cycle of the Tagus estuary turbid plume using MODIS ocean colour images

Cited by 56 publications

References 11 publications

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

The influence of the Guadalquivir river on spatio-temporal variability in the pelagic ecosystem of the eastern Gulf of Cádiz

Diurnal Variability of Turbidity Fronts Observed by Geostationary Satellite Ocean Color Remote Sensing

Contact Info

Product

Resources

About