TRMM Earth View Second Edition

TRMM Earth View
Second Edition
Land Surface Observation by TRMM/PR
Feb. 1998
Aug. 1998
Green : correspond to forest density (3 to 8 degree)
Blue : correspond to wet surface (9 to 13 degree)
Red : correspond to arid / desert areas (14 to 18 degree)
TRMM PRによる地表面観測
(協力:東京大学 生産技術研究所 沖研究室)
Land Surface Observation by TRMM/PR
– False color composites map –
These images are the false color composites showing the land surface observed by the Precipitation Radar (PR) aboard the
Tropical Rainfall Measuring Mission (TRMM) satellite for February (above) and August (below) 1998. PR observes backscatter from
rain and Earth’s surface. It scans 17 degrees across the track. Since the backscatter from 3 to 8 incident angles is highly affected
by the absorption (scattering) by vegetation canopy over the land, weaker backscatter corresponds to dense vegetation. Therefor,
dark green is used for low backscattering areas to express more dense vegetation. Since more reflectance is observed from a
wetter surface at incident angles of 9 to 13˚, blue corresponds to stronger backscatter. At 14 to 18 degrees, weaker signals are
from smoother surfaces such as deserts with mirror like surface. Dark red is used for weaker backscattering.
Thus in these false color composites,
• Green areas correspond to the areas with dense vegetation,
• Blue corresponds to wet surfaces,
• Red represents arid and desert areas, and
• Yellow represents dry grasslands (opposite to blue).
In dry areas, the color may change from green, yellow or orange to red, according to the vegetation amount. If the area is wet
enough, blue may be mixed and change to purple (less vegetation) or cyan (more vegetation). These color changes are shown
schematically as a triangle diagram in the figures.
Comparing the false color composites for February and August, the distribution of tropical rain forests in the Amazon river basin
in South America, in the Asian Monsoon region, and in the Congo river basin in Africa is clearly seen. The increase and decrease of
wet (blue) and vegetated (green) regions according to the rainy season are apparent as well.
Red, which corresponds to deserts and arid areas, is seen in the Sahara desert in Northern Africa, the Rub’ al Khali desert in the
Arabian Peninsula, and the Great Victorian desert in central Australia. Blue, which expresses soil wetness in cultivated fields and
grasslands or water surface, is seen in Sahel in Northern Africa, cultivated areas in India, Thailand and Vietnam in the rainy
The black region in Northwestern Australia indicates the missing PR observation data due to a frequency conflict. Areas thought
to be water surfaces from PR observation, such as oceans, big lakes and wide rivers, are shown in black.
(Courtesy of Oki Lab. (IIS, University of Tokyo) in cooperation with NASDA)