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| 1996 Reflectance Imagery Animations |
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NOTE: To view the animation files below, you will need to have software that allows you to play MPEG files.
If you are unable to view the files linked below, download either the free Apple QuickTime Player
or the free Microsoft Windows Media Player.
Background
The data obtained from the Advance Very High Resolution
Radiometer (AVHRR) sensors on board the NOAA satellites can be
used to derive sea surface temperaure, percent water
reflectance, and relative mixed layer depth. An AVHRR sensor can
cover an area as large as the Gulf of Mexico. For each
satellite, the same area is captured about every 12 hours.
Despite the sensor's broad spatial coverage at good sampling
rate, the AVHRR-data are seldom used to investigate daily
variability of satellite-derived parameters for an extensive time
period because the sensors are sensitive to clouds.
Movies of cloud-free daily water reflectance over Florida Bay
were developed as a framework to further exploit the AVHRR data.
Each pixel in the movies was interpolated from non
cloud-contaminated AVHRR-derived water reflectance pixels. The
interpolation technique used is evolved from the Gauss Markoff
theorem (Liebelt 1967). The estimate is influenced by the
surrounding AVHRR-derived pixels. The weigths of influence
depends on the spatial and temporal scales, and phase speeds of
the chosen parameter input by the user. The interpolation
software, "Objective Analysis Package", was developed by
Dr. A.J. Mariano at RSMAS, University of Miami. The USGS
receives raw AVHRR telemetry data from the University of South
Florida.
Each interpolated frame was saved as a TIFF formated file. Image
Magick was used to split a TIFF file into YUV files. YUV files
are files that contain lumminance, chrominance, and hue
information. Vector representations have also been added to
show changing wind speed and direction over time.
An MPEG encoder was then used to merge all of the YUV files into a movie.
Reference:
Liebelt, P.B. 1967. An introduction to optimal estimation.
Addison-Wesley Publishing Company, Reading Massachusetts.
Contributors:
Richard P. Stumpf, Varis Ransi, and Megan Frayer; USGS.
Acknowledgements: A.J. Mariano, U. of Miami
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U. S. Department of the Interior | U.S. Geological Survey
