Exploration of Satellite-Derived Ocean Color and Sea Surface Temperature Data: The Gulf Stream

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

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

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

4. Observing the Gulf Stream • We’ll use MODIS chlorophyll a and sea surface temperature data for February 2011 (monthly averages). The SST signature of the Loop Current is easier to see during winter months. • 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.

5. Gulf Stream StudyStep-by-Step Instructions • Go to GIOVANNI: http://disc.sci.gsfc.nasa.gov/giovanni • Click on “Ocean Instances” (3rd bullet), which should take you to this page: http://disc.sci.gsfc.nasa.gov/giovanni/overview/instances_climate.html • Select “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 and positive latitudes; negative numbers correspond to degrees west of the Greenwich Meridian. Then click on “Update Map”

6. Gulf Stream StudyStep-by-Step Instructions • Scroll down to the items under MODIS-Aqua 9km and click in the boxes next to • “chlorophyll a” 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 • 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”

7. February 2011 SST Chlorophyll a Similar plots may be produced for each of the 3 major sections of the Gulf Stream, using the geographic limits and suggested max and min temperatures on the following slides.

8. 36N 90W 75W 21N The Loop Current and the Start of the Gulf Stream 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.

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

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

11. Transition Zone:Departure from Coast at Cape Hatteras 42N 80W 60W 31N SST Min: 2 Max: 22 Near Cape Hatteras, the Gulf Stream leaves the coast and pushes eastward into the Atlantic

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

13. Open Ocean:Meanders and Rings 47N 68W 45W 36N SST Min: 2 Max: 16 As the Gulf Stream travels eastward across the northern Atlantic, meanders develop and occasionally break off, forming Gulf Stream “rings”, 200-300km in diameter.

14. Open Ocean:Meanders and Rings SST Chlorophyll a Like oases in a desert, cold rings are usually nutrient rich and high in chlorophyll. Warm rings are usually devoid of nutrients required for plankton blooms.

15. Education Modules • Laboratory for Ocean Color Users (LOCUS): http://daac.gsfc.nasa.gov/oceancolor/locus/index.shtml • See “Introduction to Ocean Color and SST Analysis with the Gulf Stream”