Land surface temperature interpretation of equatorial South America from AVHRR data

An important component of equatorial climate modeling is the measurement of forest transpiration rates. This in-turn is both highly correlated with, and functionally related to, forest canopy temperature. An attractive and unique way to map and monitor land surface temperatures (LST) over a large area is by the use of satellite radiometers. However, these radiometers are not only influenced by surface parameters, but also by the composition and thermal structure of the atmosphere. Therefore, the determination of LST from space requires the management of two thorny issues. The first problem is atmospheric corruption. It is common knowledge that the Earth´s atmospheric radiance contributes to the apparent brightness temperatures of the Earth´s surface itself. The second problem is the necessity to calculate a radiometric inverse. Momentarily ignoring atmospheric problems, this is the procedure which takes surface emissivity into account when calculating a surface temperature from an apparent temperature measured by the spaceborne radiometer. This report summarizes preliminary research focused on the exploration and resolution of these two issues in order to retrieve land surface temperatures from the equatorial forests of Brazil. The precise study area is the tropical forest and woodland zone of South America between 10°N and 13°S