Relationship between the ground surface temperature by NOAA-AVHRR and environmental factors
Ryuzo Yokoyama, Chang Ming Zhou, Sumio Tanba
Department of Computer Science
Faculty of Engineering, Iwate University
4-3-5 Morioka, Iwate Japan 020
Abstract
The relationship between the ground surface temperature observed by
AVHRR and the environmental factors of elevation cos
g, vegetation index, latitude and albedo were investigated by the regression analysis. In the test site of about 600kmx200km in the northern Honshu of Japan, sample points were specified at lattices with 5km distance. In an April image, no single variables had high correlation coefficients, but in June image, the elevation, the vegetation index and the albedo showed correlation coefficients higher tha 0.6. The final correlation coefficients in the multi-variate regression were 0.540.85. Large residues appeared in seaside regions and basins.
Introduction
The ground surface temperature is one of the most fundamental variables of the natural environment. As shown in
fig,1 it is determined by the balance of heat fluxes at the surface, which are participated by the five components of
R
e : Long wave radiation from the ground
R
L : long wave radiation to the ground
R
s : short wave radiation to the ground
LE : flux of latent heat,
|| : flux of sensible heat,
G : energy flux into the ground
The advent of the remote sensing has provided a new method of temperature observation. Being a spatial information at an instant, remotely sensed ground temperature images have been applied to the investigations of the environment, e.g. heat island, thermal inertia, land cover classification etc.
In this paper, we investigated the relation between the ground surface temperature observed by the NOAA-AVHRR and other environmental factors by the regression analysis. The environmental factors, which include the elevation, the vegetation index, cos, the albedo and the latitude, are selected as the variables such that they are closely related to the components of the heat balance variables such that they are closely related to the components of the heat balance variables such that they are closely related to the components of the heat balance and can be systematically read out from existing data sets by computer. Cos means the angel between the normal vectors of the ground surface and the direction of the sun light incidence at the data acquisition.
Figure 1: Heat flux balance at the ground surface.
