NASA’s Ocean Color Online Visualization and Analysis System Exploration of Satellite-Derived Ocean Color and Sea Surface Temperature Data: The Gulf Stream & Phytoplankton Blooms in the North Atlantic NASA’s Ocean Color Online Visualization and Analysis System http://disc.sci.gsfc.nasa.gov/giovanni

Observing the Gulf Stream: MODIS Sea Surface Temperature Major Sections: Loop Current and Start of Gulf Stream Transition Zone Open Ocean 3 2 1

Observing the Gulf Stream: MODIS Ocean Color Major Sections: Loop Current and Start of Gulf Stream Transition Zone Open Ocean 3 2 1

Observing the Gulf Stream We’ll use monthly averages of chlorophyll a and sea surface temperature data for February 2011 from the MODIS sensor on NASA’s Aqua satellite. The warm waters of the Loop Current and Gulf Stream are very low in chlorophyll a (plankton) concentration Warm eddies (“Gulf Stream Rings”) are also regions of very low chlorophyll a concentration. The rings are sometimes easier to see in the ocean color data.

Gulf Stream Study Step-by-Step Instructions Go to GIOVANNI: http://disc.sci.gsfc.nasa.gov/giovanni Click on “Ocean Portals”, and then “Ocean Color Radiometry Online Visualization and Analysis” which should take you here: http://gdata1.sci.gsfc.nasa.gov/daac-bin/G3/gui.cgi?instance_id=ocean_month Directly beneath the map, enter the following limits for the Area of Interest: West: -95 North: 50 South: 20 East: -40 Ensure you entered negative longitudes (which correspond to degrees west of the Greenwich Meridian) and positive latitudes (northern hemisphere). Then click on “Update Map”

Gulf Stream Study Step-by-Step Instructions Scroll down to the items under MODIS-Aqua 9km and click in the boxes next to “chlorophyll a concentration” and “sea surface temperature (11 micron day)” At the bottom of the page, enter desired year and month: 2011 February for both the begin and end dates (the temperature signature of the Loop Current is very obvious during this month) Under, “Select Visualization” click the Edit Preferences tab, and scroll to the bottom. Set the Min and Max limits for Sea Surface Temperature to 5 and 25 (use the existing chlorophyll a limits, which are .05 and 30) Click “Generate Visualization”

February 2011 SST Chlorophyll a Note: the warm Loop Current in the Gulf of Mexico the narrow Gulf Stream from Florida to Cape Hatteras, the departure from the coast at Cape Hatteras, and the meanders and eddies that begin near 070W the lack of Chlorophyll a in the warmer, open ocean waters

The Loop Current and the Start of the Gulf Stream 90W 75W 21N SST Min: 5 Max: 25 The warm loop current flows from the Gulf of Mexico through the Florida Straits, and becomes the Gulf Stream. As it flows northward along Florida, Georgia, South Carolina, and North Carolina, the Gulf Stream is relatively straight and narrow.

The Loop Current and the Start of the Gulf Stream SST Chlorophyll a

Deepwater Horizon Oil Spill - May 24, 2010 http://en.wikipedia.org/wiki/File:Deepwater_Horizon_oil_spill_-_May_24,_2010_-_with_locator.jpg

Transition Zone: Departure from Coast at Cape Hatteras 80W 60W 31N SST Min: 2 Max: 22 Near Cape Hatteras, the Gulf Stream leaves the coast and pushes eastward into the Atlantic

Transition Zone: Departure from Coast at Cape Hatteras SST Chlorophyll a

Exploring the North Atlantic Phytoplankton Blooms Click on the “Home” tab to return to the map, and expand the limits of your map to range from 20 to 65N in latitude (positive numbers) and from -85 to 0 longitude. Scroll to the items under MODIS-Aqua 9km and de-select the “sea surface temperature” box (“chlorophyll a concentration” should remain checked). At the bottom of the page, change the dates to range from 2011 January to 2012 January Under, “Select Visualization”, click on the check mark and change the type of visualization from Lat–Lon Map, Time-Averaged to “Animation” Click “Generate Visualization”. In a minute or two, you should see a frame with a chlorophyll image that you can either step through frame by frame (this works best), or loop through automatically.

March 2011 April 2011 May 2011 Note the dramatic increase in chlorophyll a near the Gulf Stream and in the eastern north Atlantic during the Spring months, and then further north during the Summer months, as sufficient sunlight becomes available for phytoplankton growth.

Education Modules Laboratory for Ocean Color Users (LOCUS): http://disc.sci.gsfc.nasa.gov/education-and-outreach/additional/science-focus/locus/index.shtml/index.shtml See “Introduction to Ocean Color and SST Analysis with the Gulf Stream”