Dr. R. J. Brown
Applications Division
Canada Centre for Remote Sensing
588 Booth Street
Ottawa, Ontario K1A 0Y7
Canada
Co-Investigators:
H. Gwyn, University of Sherbrooke
T. J. Pultz, Canada Ctr. for Remote
Sensing
Canada Centre for Remote Sensing Altona, Manitoba test site
OBJECTIVES
The overall objectives of the experiment were to evaluate the capabilities of multidate,
multiparameter
SAR
data to estimate soil moisture in an agricultural environment
for a variety of soil types in the spring and fall, develop models which provide
a better understanding on the relationships between soil moisture and texture, surface
roughness and radar frequency, polarization and incidence angle, evaluate the use
of a change detection approach for soil moisture monitoring and to gain a better
understanding of the information content of polarimetric data.
PROGRESS
Temporal changes in
SIR-C,
C- and L-band radar backscatter over the Altona site in
relation to changing environmental conditions such as frost, rain and soil moisture
have been evaluated. In addition, the soil moisture model developed by J. C. Shi
has been applied to the data.
SIGNIFICANT RESULTS
The results indicate that environmental events such as frost and rain can be monitored.
However, care must be taken as some soil targets at high moisture contents may behave
as specular reflectors at longer wavelengths, such as L-band at large incidence angles which will mask soil moisture effects. The strongest correlation (rho=.84) with
soil moisture was obtained for the 0-2.5 cm soil profile at
HH
polarizations and
was approximately the same at C- and L-band. All polarizations displayed a decrease
in soil moisture correlation with increasing soil profile depths. It was observed that soil
texture effects on the estimation of soil moisture from radar backscatter are relatively
small and can be neglected. Although the sensitivity to surface roughness is greater at
HV
and
VV
than at
HH
polarization, it is possible that roughness could be neglected
when measuring soil moisture over relatively short periods of time at a given site
without significantly reducing the sensitivity of the relationship between radar
backscatter and soil moisture. The L-band soil moisture model produced estimated values
which were in good agreement with the observed conditions.
FUTURE PLANS
Evaluation of existing soil moisture models and extension of results to
RADARSAT
data.
PUBLICATIONS
Boisvert, J. B., T. J. Pultz, Y. Crevier, R. J. Brown, B. Eilers, 1995. "Potential
of Multi-date Imagery for Soil Moisture, Texture and Drainage Classification: Preliminary
Results." 17th Canadian Symposium on Remote Sensing, Saskatoon, Saskatchewan, June 13-15, pp. 511-515.
Crevier, Y., T. J. Pultz , T. Toutin, 1995. "The Influence of Data Integration Methodology
on Multi-Source
SAR
Image Radiometry and Soil Moisture Estimation." 17th Canadian
Symposium on Remote Sensing, Saskatoon, Saskatchewan, June 13-15, pp. 448-453.
Crevier, Y., T. J. Pultz, R. J. Brown. Towards the Use of Multi-Beam
RADARSAT
Data
for Soil Moisture Estimation: Results from the CCRS
SIR-C/X-SAR
Experiment. Submitted
to 26th International Symposium on Remote Sensing of Environment/18th Canadian Symposium on Remote Sensing.
Pultz, T. J., R. J. Brown, J. Boisvert, Y. Crevier, R. Duncan, H. McNairn, D. Mullins,
D. Randall, D. Wood, P. Vincent 1994. "The CCRS SIR-C/X
SAR
Soil Moisture Experiment."
In G. W. Kite, A. Pietroniro and T. J. Pultz (ed.), Application of Remote Sensing
in Hydrology, Second International Workshop, Saskatoon, Saskatchewan, 18-20, October
1994, NHRI Symposium No. 14, pp. 34-42.
Pultz, T. J., R. J. Brown, J. Boisvert, H. Gwyn, R. Protz. "SIR-C/X-SAR Observations
of Soil Moisture over The CCRS Altona. Manitoba Test Site." IGARSS '95,
July 10-14, Florence, Italy, pp. 990-993.