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THE SIR-C/X-SAR SURFACE HYDROLOGY EXPERIMENT 
IN BRAZIL: REPORT AND PRELIMINARY RESULTS 
Jodo Vianci Soares 
Instituto Nacional de Pesquisas Espaciais - INPE 
Divisio de Metcorologia c Sensoriamento Remoto - D5M 
Caixa Postal 515 
12201-970 - Sào José dos Campos - SP, Brazil 
ISPRS Commission VII / Working Group 2 
ABSTRACT 
The SIR-C/X-SAR Mission is finally taking off on April, 7, 1994. The Shuttle will fly for about 10 days 
carrying aboard a multiparameter Synthetic Aperture Radar System: Three bands (L, C and X), four 
polarizations for L and C bands (HH,VV, VH, HV), one for X Band (VV) and incidence angles ranging 
from 159 to approximately 60°. Spatial resolution is a good as 6 meters. Processed and calibrated data in 
16 looks are to be released to Principal Investigators within two months from the experiments. The 
Bebedouro Irrigation, in the Säo Francisco River Valley (semi-arid region of northeast Brazil, 
Pernambuco state) was selected as a supersite for surface hydrology to the mission. The Bebedouro 
project which size is around 700 ha, is managed by the federal government's Brazilian Enterprise for 
Agricultural Research, EMBRAPA, with its Center for Agricultural Research for the Semi-arid, 
CEPATSA. The goals include the development of an algorithm to extract soil moisture from radar 
images, to couple radar measurements to a soil-atmosphere interface water and energy exchanges model, 
in order to obtain estimates of evapotranspiration at regional scale, and to verify the capability of radar to 
discriminate among agricultural crops grown up there. "In situ" measurements include soil, vegetation 
and other ancillary data. More specifically for soil daily sampling of moisture for the first 5 and 10 cm 
layers of the soil surface (about one 100 samples a day), soil profile humidity down to 100 cm (before the 
first data take opportunity), soil texture and soil characteristic curve (once, by the mission timing); for 
vegetation field measurements will include Leaf Area Index, state, type, density and height. Ancillary 
data will be date and depth of irrigation and routine meteorological data. We intend to present here the 
report of the report of the experiment concerning this particular study as well as the preliminary results. 
A second flight is now scheduled for August 1994. 
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