NASA’s Ocean Color Online Visualization and Analysis System Exploration of Satellite-Derived Ocean Color and Sea Surface Temperature Data: The Southwest Monsoon in the Arabian Sea NASA’s Ocean Color Online Visualization and Analysis System http://disc.sci.gsfc.nasa.gov/giovanni

Observing the Arabian Sea Monsoon We’ll use monthly averages of MODIS chlorophyll a and sea surface temperature for April through September 2004 Strong southwesterly monsoon winds drive upwelling along the coasts of Somalia and Oman High concentrations of chlorophyll a (plankton) are correlated with cold upwelled water

Southwest Monsoon Study Step-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: 42 North: 27 South: 0 East: 80 Then click on “Update Map” (in this application, west longitude and south latitude are negative, east longitude and north latitude are positive… ensure the numbers you entered are positive)

Southwest Monsoon Study Step-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: 2004 April for both the begin and end dates Under, “Select Visualization” click the Edit Preferences tab, and set the Min and Max limits for Sea Surface Temperature to 24 and 32 (use the existing chlorophyll a limits, which are .05 and 30) Click “Generate Visualization” Generate similar plots for May, by scrolling down below the figures and changing the begin and end dates, then click on “Submit Refinements”

April 2004 SST Chlorophyll a Transition period between the Northeast (Winter) Monsoon and the Southwest (Summer) Monsoon

May 2004 SST Chlorophyll a Wind-driven upwelling begins along the coasts of Somalia and Oman, as evidenced by cold water and increased chlorophyll concentrations

June 2004 SST Chlorophyll a Upwelling increases; coastal upwelling jets are evident in SST and chlorophyll concentrations along the coast of Somalia

July 2004 SST Chlorophyll a Upwelling is much stronger; elevated chlorophyll concentrations extend further out into the Arabian Sea. Monsoon cloud cover is extensive.

August 2004 SST Chlorophyll a Cold water extends across the western Arabian Sea. “Peeks” through the clouds indicate high concentrations of chlorophyll along the coast of Oman.

September 2004 SST Chlorophyll a Upwelling and cloud cover diminishes; high concentrations of chlorophyll extend throughout the northern and western Arabian Sea.

Education Modules Laboratory for Ocean Color Users (LOCUS): http://daac.gsfc.nasa.gov/oceancolor/locus/index.shtml See “Seasonal Variability”