Expedition Journal

January 23, 1996
Making Maps from Aerial Surveys

The techniques used by scientists at the Florida Marine Research Institute to monitor Florida Bay include aerial surveys and GIS.

While up in a four seater airplane, the drastic differences in the water color of the bay are apparent. One second the water is crystal clear, yet in the next second the water is green, then yellow-green then a murky brown. By flying at 1000 feet above sea level these changes in the water color become apparent. The research team has come up with a system of sixteen colors to classify the specific condition in each area. For example a Yellow Green usually indicates algal blooms.
We had to make two flights in order to cover the large survey area. During the flights, Bill Sargent and Dave Eaken noted the water colors they saw on a paper map of the bay. While recording this data, they use a navigation system called GPS to determine the exact location of the plane. Later they used their notes create a large, hand-drawn map.

After the information is transferred to the map by hand, the GIS team takes over. Courtney Westlake (known as "Crash") uses a puck to digitize the information. A puck is like a mouse on a computer except it has no wire. The map is laid out on a large plastic mat. This puck can tell where it is on the mat because the mat has a series of wires running through it in a grid-like system. The puck tells the computer the coordinates where the puck is located. By tracing out the lines, the computer generates a picture of the map.

Once the maps are digitized, Crash can use a program called ArcView to manipulate the maps. She can add colors, change sizes, and zoom in or out. The program lets her (and us) take information from many different sources and mix them together to make comparison maps. These maps can compare all the information we have gathered about the sediments in the water, and the algal blooms.

The GIS map from our aerial survey should be completed by tomorrow.

Jim Anderson, Brysen Mustain, Kristy Holland
JASON Student Argonauts

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Gene Carl Feldman (gene@seawifs.gsfc.nasa.gov) (301) 286-9428
Todd Carlo Viola, JASON Foundation for Education (todd@jason.org)
Revised: 25 Jan 1996