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Remote Sensing Algorithm Development

Remote Sensing Algorithm Development, Validation, and Applicability to Characterizing Satellite-Derived Water Quality Response to Precipitation, Discharge, and Wind in Estuaries and Coastal Ocean Areas

Abstract

Coastal areas of the United States are densely populated and the ability to monitor the health of these areas is required to sustain a quality environment. However, continuous and synoptic water quality data are lacking to characterize the response of water quality, especially in the estuaries, to in human and natural impacts. Climate variability, such as El Nino, alters precipitation, runoff, nutrient loads to the coastal areas.

The ability to quantitatively monitor water quality of coastal and estuarine systems using remote sensing technology can benefit from (1) the advances in optical physics to better estimate chlorophyll, other pigments, and light attenuation, particularly in turbid coastal waters, and; (2) finer spatial resolution of the ocean color sensor from 1100 to 250 meter for the red band (which can be used as a surrogate for turbidity); and from 1100 to 500 m for the blue and green bands on MODIS (the MODerate Resolution Imaging Spectroradiometer). Hereafter, the 250 meter and 500 meter MODIS bands will be referred to as MODIS “high” resolution bands since the resolution for other MODIS bands is 1100 m.

The purpose of this study is to evaluate whether or not the modified MODIS land bands can be used to accurately estimate the red, blue, and green water reflectance from the MODIS high resolution bands; where the red band can be used as a turbidity surrogate and the combination of blue and green band may estimate surface chlorophyll concentration. And, if the answer is positive, characterize the response of the derived water reflectance respond to the different magnitudes and duration of precipitation, discharge and wind events, from episodic to seasonal to annual. A time series of the data may be useful for other eutrophication related studies. However, the caveat with the high resolution bands is that they were developed for land applications and water reflectance cannot be readily retrieved. Thus, before the evaluation process begins, we will tweak the current atmospheric correction (an algorithm that estimates the atmospheric interferences between the sensor and water surface and that the water reflectance is approximately the total radiance received at the top of the atmosphere minus the atmospheric interferences) in order to retrieve water reflectance at MODIS high resolution bands. The project is currently funded by NASA. It is also hoped the development and experiment will be applicable to upcoming sensors, VIIRS and GOESR.

Objectives

  • Develop an algorithm to estimate water reflectance from the MODIS high resolution bands.   
  • Evaluate the applicability of the MODIS high resolution bands to monitor and characterize water reflectance in coastal waters. 

Time Frame

2007.

For More Information

Project Manager:
Varis.Ransi@noaa.gov
1305 East West Highway
SSMC-IV, N/SCI-1
Silver Spring, MD 20910
301-713-3028 x142