SaWS Clickable Map

Currently, SaWS covers the entire Intra-Americas Sea, western Tropic Atlantic, and Bermuda. To facilitate visualization and navigation, the imagery products are divided into different geographic regions, for example Central Atlantic, Eastern Caribbean, Western Gulf of Mexico, Bermuda, etc. The "SaWS Clickable Map" at top of this paragraph shows the current coverage, where any region can be clicked to open a separate page unique to that region. A user may then select a specific date on the calendar, or use the “animate” function to browse through the image sequence quickly to determine the date of interest. A screenshot of a typical web interface is presented below.

Virtual Antenna Web Interface
Virtual Antenna Web Interface
LaboratoryThe information of each image type can be obtained by clicking on the “Information” link”

Currently, VBS covers selected regions in the Gulf of Mexico, Cape Code, and Persian Gulf. In the future other regions may be added, depending on user needs and processing capacity. The current regions include:

Florida Panhandle [each links to its own page in a popup window] Apalachicola Bay Offshore Apalachicola Bay Saint George Sound Offshore Saint George Sound Saint Joseph Bay Offshore Saint Joseph Bay Saint Andrew Bay Offshore Saint Andrew Bay Perdido Bay, Pensacola Bay Offshore Pensacola Bay Choctawhatchee Bay Offshore Choctawhatchee Bay Florida Big Bend Apalachee Bay Offshore Apalachee Bay Steinhatchee River Suwannee River Central West Florida Charlotte Harbor Sarasota Bay Tampa Bay West Florida Shelf Florida Keys Florida Reef Tract Florida Straits Southwest Florida Birght Cape Cod Northern Persian Gulf

Two Sargassum Species
Two Sargassum Species
Caribbean Sargassum: Sargassum natans (left) and Sargassum fluitans (right).
University of South Mississippi
Beaching Event
Beaching Event 2015
Sargassum accumulates along Bathsheba Beach on the east coast of Barbados
(courtesy of Romel Hall/Barbados Today)

   SaWS Clickable Map

Estuaries and coastal zones are under influence of both climate variability and human impacts, and it is desirable to assess their water quality state and anomaly events to facilitate coastal management. The virtual buoy system (VBS) is established here to meet such needs through satellite measurements, algorithm development, data product customization, and data sharing. The VBS is based on a virtual antenna system (VAS) that obtains low-level satellite data and generates higher-level data products using both NASA standard algorithms and regionally customized algorithms in near real-time. The VB stations are predefined and carefully chosen to cover water quality gradients in estuaries and coastal waters, where multi-year time series of a variety of water quality parameters at monthly and weekly intervals are extracted and displayed. Details can be found in Hu et al. (2014)

   SaWS Clickable Map

Three basic steps are used to implement the VBS.

The first is to prepare satellite data products from individual satellite passes. This is through the VAS. Low-level data are downloaded from NASA [link to oceancolor.gsfc.nasa.gov] every day in near real-time, and then processed using the software SeaDAS and software and algorithm written in house. The data products are stored in HDF files

.

The second is to design the VBS locations. These are based on user needs, the processing capacity at Optical Oceanography Laboratory (OOL), and water quality gradients in a specific region. Typically, for a region of interest, there are several to several 10s of VBS locations. These locations are displayed on a “clickable” map, where a user can click on any of these pre-defined locations to visualize water quality data.

The third is to query the HDF files (step 1) for each of the locations (step 2) to extract and plot the water quality data, with results saved in ASCII data file and png image file. This step is performed once every week to update all the time series data.

Finally, depending on the region, the water quality data may include some or all the following parameters: sea surface temperature (SST, oC), chlorophyll-a concentration (Chla, mg m-3), turbidity (NTU), diffuse light attenuation at 490 nm (Kd(490), m-1) or secchi disk depth (SDD, m), absorption coefficient of colored dissolved organic matter (CDOM), and bottom available light (BAL, %). The description of each parameter can be found under its corresponding tab on the web page.

Examples

Go to “Where to Find VBS Data” tab above, select one of the predefined regions, which will lead to the following steps. Fig. 1 below shows an example of the “clickable map” where the VBS locations are annotated. A mouse click on a location will bring a summary water quality page for that station, as shown in Fig. 2. A mouse click on one of the water quality tabs will bring the time series data and graph, as shown in Fig. 3. Fig. 1. A sample “clickable map” showing the VBS locations for the Central West Florida. A mouse click on one of the stations will bring a summary water quality table for that station (Fig. 2). Fig. 2. A screenshot showing summary tab for one VBS station. In the menu each individual water quality parameter is listed as a separate tab than can be clicked on. A click on the “Kd” tab will display all time series Kd data in both ASCII and graphic formats, as shown in Fig. 3. Fig. 3: A sample screenshot showing light attenuation time series for a VBS station.

   SaWS Clickable Map

Currently, SaWS covers the entire Intra-Americas Sea, western Tropic Atlantic, and Bermuda. To facilitate visualization and navigation, the imagery products are divided into different geographic regions, for example Central Atlantic, Eastern Caribbean, Western Gulf of Mexico, Bermuda, etc. The "SaWS Clickable Map" at top of this paragraph shows the current coverage, where any region can be clicked to open a separate page unique to that region. A user may then select a specific date on the calendar, or use the “animate” function to browse through the image sequence quickly to determine the date of interest. A screenshot of a typical web interface is presented below.

Virtual Antenna Web Interface
Virtual Antenna Web Interface
LaboratoryThe information of each image type can be obtained by clicking on the “Information” link”

   SaWS Clickable Map

Under each images icon in the VAS (previous tab) there is a small GE button in the lower right corner. When this is clicked, a KML file is generated for that image. In addition, surface currents from the Hybrid Coordinate Ocean Model (HYCOM — from the National Ocean Partnership Program (NOPP)) are obtained, updated nightly, and made available via the VAS as a layer within Google Earth. Thus, both the image and surface currents can be displayed in Google Earth with a simple mouse click (see example below), thereby facilitating visualization and navigation. Within Google Earth, once a Sargassum raft is identified with latitude and longitude, current speed and direction (available through a mouse click over the current vector) near the raft can be used to predict the movement of the raft and a possible beaching time, in essence, forming an early warning system.

Ocean Currents Vectors Integrated with Satellite Imagery in Google Earth
Google Earth Interpretation
A KML file is created to provide Google Earth the image and ocean current data for visualization

   SaWS Clickable Map

Sargassum has impacted the Caribbean in so many ways. Here we show a few photographs that reveal the serious nature of the problem.

Capesterre Guadeloupe
Capesterre
Airborne survey during spring and summer 2015
(photo courtesy of Jean-Philippe Maréchal)
Desirade Guadeloupe
Desirade
Airborne survey during spring and summer 2015
(photo courtesy of Jean-Philippe Maréchal)
Martinique
martinique_2015a
Sargassum Beaching Event 2015
(photo courtesy of Jean-Philippe Maréchal)
Martinique
martinique_2015b
Sargassum Beaching Event 2015
(photo courtesy of Jean-Philippe Maréchal)
Sailing Vessel Skipping Stone
Capesterre
Stranded boat in a Sargassum bloom off Admiralty Bay, Bequia, Grenadines
June 2015 (Photo credit: Sailing Vessel Skipping Stone)

  SaWS Clickable Map

Dierssen, H. M., A. Chlus, and B. Russell (2015). Hyperspectral discrimination of floating mats of seagrass wrack and the macroalgae Sargassum in coastal waters of Greater Florida Bay using airborne remote sensing. Remote Sens. Environ., 167:247-258.

Feagin, R. A. and A. M. Williams (2010). Sargassum: Erosion and Biodiversity on the Beach, Spatial Sciences Laboratory, Dept. Ecosystem Science & Management, Texas A&M University, pp23.

Franks, J., D. R. Johnson, D. S. Ko, G. Sanchez-Rubio, J.R. Hendon, and M. Lay (2011), Unprecedented Influx of pelagic Sargassum along Caribbean island coastlines during summer 2011, Proc. Gulf Caribb. Fish. Inst., 64:6-8.

Gower, J., C. Hu, G, Borstad, and S. King (2006), Ocean color satellites show extensive lines of floating Sargassum in the Gulf of Mexico, IEEE Trans. Geosci. Remote Sens., 44, 3619–3625.

Gower, J., E. Young, E., and S. King (2013), Satellite images suggest a new Sargassum source region in 2011, Remote Sens. Lett. 4, 764–773.

Hardy, R. F. (2014). Assessment of surface-pelagic drifting communities and behavior of early juvenile sea turtles in the Northern Gulf of Mexico. MS Thesis, University of South Florida, 118pp.

Hu, C (2009), A novel ocean color index to detect floating algae in the global oceans, Remote Sens. Environ., 113, 2118–2129.

Hu, C., B. B. Barnes, B. Murch, and P. Carlson (2014), Satellite-based virtual buoy system (VBS) to monitor coastal water quality, Optical Engineering, 53, 051402. doi: 10.1117/1.OE.53.5.051402.

Hu, C., L. Feng, R.F. Hardy, and E. J. Hochberg (2015), Spectral and spatial requirements of remote measurements of pelagic Sargassum macroalgae, Remote Sens. Environ., 167, 229-246. doi: doi:10.1016/j.rse.2015.05.022

Huffard, C. L., S. von Thun, A. D. Sherman, K. Sealey, and K. L. Smith Jr. (2014). Pelagic Sargassum community change over a 40-year period: temporal and spatial variability. Mar. Bio, 161:2735-2751

Lapointe, B. E., L. E. West, T. T. Sutton, and C. Hu (2014), Ryther revisited: nutrient excretions by fishes enhance productivity of pelagic Sargassum in the western North Atlantic Ocean, J. Exp. Mar. Bio. Ecol. 458:46-56.

Milledge, J. J., B. V. Nielsen, and D. Bailey (2015). High-value products from macroalgae: the potential uses of the invasive brown seaweed, Sargassum muticum. Reviews in Environmental Science and Bio/Technology. 15:67-88.

Parr, A.E. (1939), Quantitative observations on the pelagic Sargassum vegetation of the western North Atlantic, Bull. Bingham Oceanog. Coll., Peabody Museum of Natural History, Yale University, 6(7): 1-94. Oceanography 28(3):8–10

Sargasso Sea Commission (link: http://www.sargassoseacommission.org/publications-and- news/worldwide-sargassum)

The Journey of the Sargassum forum (link: http://ambergriscaye.com/forum/ubbthreads.php/topics/506457/the-journey-of-the-sargassum.html)

Smetacek, V., and A. Zingone (2013). Green and golden seaweed tides on the rise, Nature, 504:84-88.

Webster, R. K., and T. Linton (2013), Development and implementation of Sargassum Early Advisory System (SEAS), Shore and Beach, 81(3): 1 – 6.

Wang, M., and C. Hu (2016), Mapping and quantifying Sargassum distribution and coverage in the Central West Atlantic using MODIS observations, Remote Sens. Environ., in press.

Witherington B., H. Shigetomo, and R. Hardy (2012), Young sea turtles of the pelagic Sargassum-dominated drift community: habitat use, population density, and threats, Mar Ecol Prog Ser 463: 1-22.