The image above is an "evaluation product" that indicates water clarity as the euphotic depth, or 1% light level, i.e. the depth at which the light intensity is 1% of the light intensity at the surface. The euphotic depth product is available in the Ocean Biology Processing Group (OBPG) Level 3 Data Browser, for a period in November 2007 during the validation process for this product. When validation is completed, the data product will be processed over the mission duration. (Text written 02/20/2008)
Chesapeake Bay as observed by SeaWiFS and MODIS-Aqua
The image below for August 12, 2007 was acquired from the NOAA Coastwatch East Coast Node, which is linked from the Chesapeake Bay validation site of the OBPG.
Chesapeake Bay with Giovanni and NEO
The prototoype Giovanni-NEO Instructional Cookbook features a chapter on the Chesapeake Bay. The images below are (top left) chlorophyll a concentration, (top right) diffuse attenuation coefficient at 490nm (K490), and (bottom) normalized water-leaving radiance at 555nm (nLw555). Despite the difficulties of accurately measuring these quantities from space in shallow waters, each of them provides information about water quality. K490 indicates the clarity of the water, and nLw555 is sensitive to reflection from inorganic sediments and the seafloor (or the bay bottom).
250-meter resolution image of the Chesapeake Bay using the 645nm band
This image is from the presentation "MODIS Land Bands for Ocean Remote Sensing". The 645 nm band is particularly useful to examine surface turbidity.
The link to the PDF file below may not work if you attempt to open it in your Web browser. We recommend clicking on it and then saving it to your computer using the "Save Link As" command, and then opening it with Acrobat Reader.
MODIS Land Bands for Ocean Remote Sensing
Sea Level Rise and Climate Change
Projections of sea level rise based on the melting of the Greenland ice sheet indicate that a rise of 6 meters is possible within centuries. NASA GSFC scientists monitor snow and ice, the global water cycle, and the oceans, with NASA satellites to investigate current and future climate change. Climate change processes may impact the coastal zone, water resources, and water quality regionally and globally.
Links to other NASA Web sites concerned with water quality: