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Th e west Florida continental shelf is a broad, gently sloping region about as wide as the State of Florida. Shown are bottom depth contours, the various locations referred to in the text, and the measurement sites. Attention should be focused on the region between Tampa Bay and Charlotte Harbor, where cold water is observed to outcrop, and the Florida Big Bend region, where these outcropping cold waters are thought to have originated by deep-ocean water broaching the shelf break. Th e arrow indicates the approximate pathway taken from the shelf break to the near shore. Th e line segment and the solid dot off shore of Sarasota denote the positions of the Figure 3 temperature section and the Figure 5 velocity data, respectively. Th e small, closed, 20-m contour region toward the bottom of this Figure encircles the Dry Tortugas.
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Author Posting. © Oceanography Society, 2004. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 17, 2 (2004): 68-75. Satellite-sensed ocean optical features are derived from a combination of factors, including the concentration of water pr...
Context in source publication
Context 1
... is because temperature, with provision for surface heating and cooling, is a conservative variable, as contrasted with pigment-related variables that may be highly non-conser- vative. (Figure 1; Weisberg and He, 2003;Walsh et al., 2003). shore, provided the conduit for these cold, nutrient-rich waters to reach the coast. ...
Citations
... Available velocity observations (again by moored ADCPs) demonstrated the general veracity of these model findings, and together, these observations and model simulations provided a confirmation of the Hetland et al. (1999) model-derived hypothesis. With the Loop Current forcing beginning in March, the observations and model simulations showed the Loop Current effects building toward the end of April with the entire WFS affected by May (Weisberg et al., 2004). Using a data assimilative model, Fan et al. (2004) then showed that such an upwelling circulation could also be obtained by assimilating surface drifter observations. ...
We review the evolution of knowledge on the forcing of the west Florida continental shelf by a combination of local winds and deep-ocean influences, and we provide application examples regarding the relationships between the shelf responses to these forcing functions and certain ecological phenomena, including blooms of the harmful alga, Karenia brevis, recruitment of gag juveniles and how Deepwater Horizon hydrocarbons may have affected west Florida reef fish and the shoreline. Our approach employs a coordinated set of observations and numerical circulation model simulations, wherein the observations, by providing reasonable veracity checks on the model simulations, allow for further dynamical analyses that would otherwise be unavailable from the observations alone. For the case of local forcing only, we provide two dynamically consistent definitions of the inner-shelf and outer-shelf regions, and for the case of deep-ocean forcing, we show how the west Florida shelf geometry (with regard to certain geophysical fluid dynamics principles) can result in the entire shelf region being impacted by the Gulf of Mexico Loop Current. Thus, we help to explain why the west Florida shelf experiences large inter-annual variations in shelf ecology, providing impetus for further interdisciplinary study.
... Different experiments have shown how different information sources, remote sensing and otherwise, can be combined to help the interpretation of ecosystem conditions, particularly in a three-dimensional context (Gould and Arnone 1998;Weisberg et al. 2004). Gould et al. values are found by OC processing, it is possible that they are largely erroneous. ...
This report on "Uncertainties in Ocean Colour Remote Sensing" summarizes the state of the knowledge on uncertainties related to ocean colour (OC) products and identifies ideas and recommendations to achieve significant progress on how uncertainties are quantified and distributed. The report starts with a presentation of terminology and concepts (Chapter 2). For a proper use of OC data, it is necessary to be aware of the potential problems and limitations associated with OC remote sensing products, and to identify the sources contributing to their uncertainties, from top-of-atmosphere (TOA) data to gridded products. This report makes a review of these factors (Chapter 3). Even though up to now very few OC products have been distributed with uncertainty estimates, a number of approaches to quantify OC product uncertainties have been proposed in recent years; providing a review of these methods and discussing their respective advantages appear particularly timely (Chapter 4). It is also necessary to discuss how information on uncertainty could be conveyed to user communities (Chapter 5) and to describe example requirements from these communities (Chapter 6). General recommendations are provided in the final chapter (Chapter 7).
... As such, changes in the frequency, extent, seasonality, or magnitude of the LC and its shedding events would affect the SST temperatures in the location of the LC, but also propagate away from that region. Moreover, changes to the LC expansion and shedding process could alter its interaction with continental shelves and potentially affect coastal upwelling throughout the region, entrainment and transport of water from the Mississippi River, and transfer of heat, mass, and momentum within the GoM and between adjacent water bodies [55] [71] [76] [77]. To have contributed to the spatial and temporal SST patterns of the GoM found in the current research, however , the LC would have to possess a multidecadal periodicity. ...
This work examines the spatial and temporal patterns of seasonal sea surface temperatures (SSTs) across the Gulf of Mexico (GoM) for the period 1901-2010. The Extended Reconstructed Sea Surface Temperature, version 4 (ERSST.v4), dataset was selected for this study over other reconstructions because of its 2˚×2˚× 2˚grid2˚grid cell spatial resolution, its recent update to adjust for known biases in SST observations, and its ability to be compared to other in situ studies of GoM SSTs. The monthly ERSST.v4 data were averaged seasonally for each year and grid cell in the GoM. Seasonal SST trends were then calculated for each grid cell with varying start dates (e.g., 1901-2010, 1911-2010) to account for nonlinear SST changes over the study period. Results indicate that the GoM SSTs closely resemble those of global annual temperature trends: SSTs warmed from 1901 to ~1940, followed by a period with little trend or a slight cooling until the mid-1970s, and then a warming afterwards through 2010. The spatial patterns and magnitudes of SST changes, however, varied by season and location within the GoM. The spatial patterns involved gradients with latitu-dinal and/or longitudinal components: a southwest-northeast (warmer-cooler) gradient in winter, an east-west (warmer-cooler) gradient in spring and fall, and a northwest-southeast (warmer-cooler) gradient in summer. The magnitude of SST changes tended to be largest in summer, followed by spring, fall, and winter. The long-term (1901-2010) SST trends were significant throughout the GoM in summer and fall, but only significant towards the southwestern GoM in winter and spring. These results have implications in discussion of climate change and its impacts on tropical activity in the GoM Basin. Keywords Sea Surface Temperature, Gulf of Mexico, Temperature Reconstructions, Temperature Variability J. Allard et al. 315
... Variations in sea-surface temperature (SST) along the West Florida Shelf (WFS), Florida Bay, and the Florida Keys commonly result from anomalies in incoming and outgoing solar radiation, surface air-sea heating and cooling effects (e.g., latent and sensible heat fluxes), coastal upwelling, and deep water mixing (Weisberg et al. 2004;Gramer 2013). SST variations occur over a broad range of time scales, including diurnal, weekly, seasonal, and interannual duration. ...
... Causes of these variations include the passage of synoptic-scale weather systems such as cold fronts and storms during winter and tropical systems, diurnal insolation, and tidal fluctuations during summer and fall (Gramer 2013;Morey et al. 2006;Monaldo et al. 1997). For example, with a cold front passage, the entire water column in shallow coastal areas may cool by several degrees due to sensible and latent heat losses (Joyce 2002;Weisberg et al. 2004). These surface-induced changes along with upwelling-related processes, mixing, and advection are considered dominant controlling factors on short-term temperature response in this region. ...
Water temperature is considered both a controlling and lethal factor in coastal ecosystems, influencing behavioral and physiological responses in marine organisms. Abrupt weather events such as severe cold front passages and accompanied changes in weather conditions have led to sharp decreases in water temperatures, metabolic stress, and incidences of mortality in marine organisms. In this paper, we assess the weather-related factors associated with physical and biological response in South Florida systems through historical sea surface temperature (SST) from satellites and the use of a synoptic climatology spanning over 30 years. We utilize previous categorizations of sea-level pressure and newly developed categorizations of 850-mb temperature reanalysis data to define circulation and temperature patterns across the southeastern US and adjacent Gulf of Mexico. Systematic connections are seen between particular circulation and temperature patterns characteristic of enhanced north-to-south circulation and cold air outbreaks, SST, and turtle strandings data over the Florida Panhandle region for the period 2006–2013. Identified weather forcing variables associated with sharp SST decreases and turtle stuns are presented and assist in the formulation of a moving cold-stress index for South Florida coastal ecosystems. Results demonstrate the potential of using synoptic climatological analysis and derived indices for tracking and modeling changes in SST and other indicators related to biological health.
... The directionality of the near bottom (Ekman layer) flow and the fact that the shelf width between Tampa Bay and Charlotte Harbor is relatively narrow compared with points farther north (or south) both conspire to make this Tampa Bay and Charlotte Harbor region one of maximum upwelling near shore. These pathway arguments were previously documented, either for synoptic weather scale events (e.g., Weisberg et al., 2000Weisberg et al., , 2001Weisberg et al., , 2005, or for the anomalous 1998 conditions (e.g., Weisberg and He, 2003;Weisberg et al., 2004) so they are not unique to 2010. Given the pathway of new, nutrientrich water ingress to the WFS at depth in the northwest, the flow egress from the WFS back to the deep ocean (as seen in Fig. 4) is in the vicinity of the Dry Tortugas in the south. ...
... In situ data collected at the station 10 km NW of Station 78 showed a CDOM (440) ¼ 0.37 m À1 , a ph (440) ¼ 0.08 m À1 , and a d (440) ¼ 0.02 m À1 , confirming the CDOM dominance of both absorption and reflectance at 440 nm and explaining the overestimation in SeaWiFS Chl-a. Given the high discharge observed during the entire winter-spring of 1998 (Figure 9) as well as the corresponding high-CDOM and low-salinity waters on the shelf (Nababan, 2005), it is likely that SeaWiFS Chl-a was overestimated in nearshore waters, which was influenced by terrestrial outflow during this time (Figures 6 and 7); however, adding to this complexity is nutrient-rich coastal upwelling that also occurred during this time, possibly fueling phytoplankton growth in nearshore waters (Weisberg et al., 2004). ...
Despite the importance of the West Florida Shelf (WFS) on regional ecology and local economy, systematic shelf-wide assessment of the ocean biology has not been conducted, primarily because of budgetary limitations for routine field campaigns and unknown accuracy of satellite-based data products. Here, using shipboard spectral normalized water-leaving radiance (nL(w)[lambda]) data and chlorophyll-a concentrations (Chl-a) collected regularly during two multiyear field programs spanning >10 years, the accuracies of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) standard data products were evaluated. The in situ data covered a wide dynamic range, with about one order of magnitude in nL(w)(490) (0.47 to 4.01 mW cm(-2) mu m(-1) sr(-1)) and two orders of magnitude in Chl-a (0.07 to 10.6 mg m(-3)). Near-concurrent in situ and satellite nL(w)(lambda 2) data showed absolute percent differences (APD) increasing from 7-9% to 10-14% when data with elevated aerosol optical thicknesses at 865 nm (tau(alpha)865) were included. Most of this uncertainty, however, canceled in the maximal blue-to-green reflectance band ratios traditionally used for estimating Chl-a. SeaWiFS OC4 Chl-a showed a root mean square (RMS) uncertainty of 0.106 for log-transformed data in waters offshore of the 20-m isobath that increased to 0.255 when all data were considered. The increased likelihood for nearshore SeaWiFS Chl-a greater than similar to 0.5 mg(-3) to be overestimated was shown to be caused by a variety of factors (colored dissolved organic matter [CDOM], suspended sediments, and bottom reflectance) that varied in both time and space. In the future, more sophisticated algorithms capable of taking these factors into consideration are required to improve remote determinations of Chl-a in nearshore waters of the WFS.
... Several studies have shown processes at depths (e.g. upwelling) using numerical models and vertical profiles at fixed locations (Walsh et al., 2003(Walsh et al., , 2006Lenes et al., 2008Lenes et al., , 2012Weisberg and He, 2003;Weisberg et al., 2004Weisberg et al., , 2009). The only proof-of-concept study using AUVs was conducted by Robbins et al. (2006), who deployed an AUV equipped with an optical phytoplankton discriminator (OPD, Kirkpatrick et al., 2000Kirkpatrick et al., , 2003 to map the K. brevis bloom in 2005, track its movements, and examine the relationships between OPD data and temperature, salinity, chlorophyll-a, cell concentration, and ocean currents. ...
... Subsequent movements to the north for a few days followed by persistent transport to the south are also supported by the evolution of the simulated velocity fields. Hence there is no inconsistency between previous hypotheses of generation offshore (Tester and Steidinger, 1997;Walsh and Steidinger, 2001) and advection onshore via the bottom Ekman layer Weisberg, 2011;Weisberg et al., 2004Weisberg et al., , 2009. ...
... N, 82.5468 W) located between Tampa Bay and Charlotte Harbor on the 10-m isobath. was overestimated in nearshore waters, which was influenced by terrestrial outflow during this time (Figures 6 and 7); however, adding to this complexity is nutrient-rich coastal upwelling that also occurred during this time, possibly fueling phytoplankton growth in nearshore waters (Weisberg et al., 2004). ...
Despite the importance of the West Florida Shelf (WFS) on regional ecology and local economy, systematic shelf-wide
assessment of the ocean biology has not been conducted, primarily because of budgetary limitations for routine field
campaigns and unknown accuracy of satellite-based data products. Here, using shipboard spectral normalized waterleaving
radiance (nLw[k]) data and chlorophyll-a concentrations (Chl-a) collected regularly during two multiyear field
programs spanning .10 years, the accuracies of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) standard data
products were evaluated. The in situ data covered a wide dynamic range, with about one order of magnitude in nLw(490)
(0.47 to 4.01 mWcm�2 lm�1 sr�1) and two orders of magnitude in Chl-a (0.07 to 10.6 mg m�3). Near-concurrent in situ and
satellite nLw(k) data showed absolute percent differences (APD) increasing from 7–9% to 10–14% when data with
elevated aerosol optical thicknesses at 865 nm (sa865) were included. Most of this uncertainty, however, canceled in the
maximal blue-to-green reflectance band ratios traditionally used for estimating Chl-a. SeaWiFS OC4 Chl-a showed a root
mean square (RMS) uncertainty of 0.106 for log-transformed data in waters offshore of the 20-m isobath that increased to
0.255 when all data were considered. The increased likelihood for nearshore SeaWiFS Chl-a greater than ~0.5 mg m�3 to
be overestimated was shown to be caused by a variety of factors (colored dissolved organic matter [CDOM], suspended
sediments, and bottom reflectance) that varied in both time and space. In the future, more sophisticated algorithms
capable of taking these factors into consideration are required to improve remote determinations of Chl-a in nearshore
waters of the WFS.
... Whereas local forcing alone could account for many observed features, it became abundantly clear that under certain conditions the deep ocean may have a profound effect on WFS water properties, especially when the Gulf of Mexico Loop Current impacts relatively shallow isobaths offshore from the Dry Tortugas (the western terminus of the Florida Keys). Remote forcing there can cause upwelling even as far away as DeSoto Canyon, and subsequent transport across the WFS can alter water properties along the shoreline in the south Weisberg et al., 2004). Driven by the circulation, the responses to the biota may also be profound (Walsh et al., 2003). ...
... But this circulation is far from two dimensional. For instance water that may upwell to the surface near Sarasota FL may originate in the Florida Big Bend region (e.g., Weisberg et al., 2004). Owing (in this instance) to the Loop Current impact the surface water of the WFS is exiting to the deep ocean as a concentrated jet in the southwest. ...
... March/April 2011 Volume 45 Number 2 advection of nutrients onto the shelf and then both along and across the shelf, contributing to the local productivity evident along the bottom. Such occurrences for the West Florida Continental Shelf (WFS) are a general finding (e.g., Weisberg et al., 2004). ...
