Studies of Tropical Vegetation

The MERS research group has been actively involved in research involving the Amazon, Congo and other tropical rain forests. As part of these studies both Seasat scatterometer (SASS) and ERS-1 scatterometer (Escat) data have been processed with the SIRF resolution enhancement algorithm. This algorithm was developed by the MERS group to generate enhanced resolution scatterometer imagry.

SIRF images have demonstrated the ability to enable the discrimination of tropical vegetation types and have been very useful in polar ice studies.

SIRF generates images of A and B which are related to the normalized radar cross section Sigma-0 by Sigma-0(db)=A+B(theta-40) where theta is the incidence angle of the measurements. The resolution of the resulting images is ~4-5 km for SASS, 25-30 km for ERS-1/2, and 4-8 km for NSCAT. Previous techniques were limited to the intrinsic resolution (50 km) of the scatterometer.

Sample images over the Amazon rainforest are avilable below.

Want to know that the world looks like by radar?

NSCAT used 14 GHz (Ku-band) to observe the Earth.

World view from NSCAT data:
Display NSCAT b/w world image (size=402k)
Display colorized NSCAT world image (size=383k)

Global view of Ku-band Sigma-0 at 40 deg incidence angle (size=75k) Display SASS image

The European ERS-1 and ERS-2 AMI scatterometers used 5.3 GHz (C-band).

Global view of C-band Sigma-0 at 40 deg incidence angle over land with wind Overlay (size=162k) Display ERS-1 image

Low resolution SASS image of the Amazon: (size=122k)
Display low resolution Image

SIRF enhanced resolution SASS image of the Amazon: (size=157k)
SIRF Image

SIRF enhanced resolution NSCAT image of the Amazon:
Display small b/w image (size=159k)
Display b/w image (size=523k)
Display colorized image (size=492k)

Comparing the SASS and NSCAT images, the changes in the past two decades can be evaluated. In this image, smaller changes (1 sigma difference std) have been highlighted in yellow and larger changes (more than 2 sigma differences) are in pink. Changes correlate well with highway and settlement development.

NSCAT-SASS change image of the Amazon:
Display image (size=193k)

Other vegetation/land images

SASS A image of Africa and the Congo (size=399k)
Display image

Small ERS-1 Africa image time series (size=26k)
Display image

Alaska SASS image time series (size=154k)
Display colorized image

Alaska NSCAT images (size=293k)
Display b/w image

NSCAT image of Japan (size=53k)
Display b/w image

Some of the most spectacular images are of the polar regions...
Images of Antarctica
Images of Greenland

Related Papers

Resolution Enhancement of Spaceborne Scatterometer Data

D.G. Long, P. Hardin and P. Whiting, IEEE Trans. Geosc. Remote Sens., Vol. 31, No. 3, pp. 700-715, May 1993.

Vegetation Studies of the Amazon Basin Using Enhanced Resolution Seasat Scatterometer Data

D.G. Long and P. Hardin, IEEE Trans. Geosc. Remote Sens., Vol. 32, No. 2, pp. 449-460, March 1994.

MERS Bibliography