Physical Basis for Microwave Remote Sensing ...
where
backscattering coefficient of forest canopy
total attenuation of forest canopy
backscattering coefficient of snowpack without forest canopy.
523
The absorption of boreal forest canopies has been observed to be less than 0.5 dB at 24 GHz;
hence it is even smaller in the frequency ranges used by present spaceborne radars (1 to 10 GHz).
The forest canopy contribution increases with increasing biomass; however, the contribution
from the snow-covered ground decreases almost by the same amount.
18.6 Future Aspects
ESA will launch its MIMR microwave radiometer after the year 2000. MIMR operates at six
frequencies covering the 6.6 to 89 GHz range. Its spatial resolution will be better than that
of previous spaceborne radiometers (4 to 5 km at 89 GHz). The recently launched ERS-2
guarantees availability of C-band SAR data for several years. The Canadian RADARSAT will
be launched in September 1995. The SAR will provide C-band HH polarized data with a
substantially wider swath (up to 500 km) than the ERS-1 SAR sensors (100 km).
18.7 References
Anderson DL (1960) The physical constants of sea ice. Res Appl in Industry 13: 310-318
Arcone SA, Gow AG, McGrew S (1986) Structure and dielectric properties at 4.8 and 9.5
GHz of saline ice. J Geophys Res 91: 14281-14303
Assur A (1960) Composition of sea ice and its tensile strength. U.S. Army Snow and Ice and
Permafrost Res Establ, Wilmette, IL
Carsey FD, Barry RG, Weeks WF (1992) Introduction, Chapter 1 in: Carsey, F.D. (editor),
Microwave remote sensing of sea ice, American Geophysical Union Monograph 68, Washington,
DC, USA
Colbeck SC (1982) The geometry and permittivity of snow at high frequencies. Journal of
Applied Physics 53: 4495-4500
Cumming W (1952) The dielectric properties of ice and snow at 3.2 cm. Journal of Applied
Physics 23: 768-773
Debye P (1929) Polar Molecules, Dover, New York
Evans S (1965) Dielectric properties of ice and snow - a review. Journal of Glaciology 5:
773-792
Foster JL, HaIl DK, Chang ATC, Rango A (1984) An overview of passive microwave
snow research and results. Reviews of Geophysics and Space Physics 22, no. 2: 195-208
Foster JL, Chang ATC (1992) Snow cover, in: Guerney RJ, Foster JL, and Parkinson CL
(editors), Atlas of satellite observations related to global change, University Press, Cambridge
Gloersen P, Nordberg W, Schmugge TJ, Wilheit TT, Campbell WJ (1973) Microwave
signatures of first-year and multiyear sea ice. Journal of Geophysical Research 78: 3564-3572
Gray AL, Hawkins RK, Livingstone CE, Arsenault LD (1981) Seasonal effects on the
microwave signatures of Beaufort Sea ice, Proc. 15th International Symposium on Remote
Sensing of the Environment, pp. 239-257, Ann Arbor, Michigan, USA, May 11-15
where
backscattering coefficient of forest canopy
total attenuation of forest canopy
backscattering coefficient of snowpack without forest canopy.
523
The absorption of boreal forest canopies has been observed to be less than 0.5 dB at 24 GHz;
hence it is even smaller in the frequency ranges used by present spaceborne radars (1 to 10 GHz).
The forest canopy contribution increases with increasing biomass; however, the contribution
from the snow-covered ground decreases almost by the same amount.
18.6 Future Aspects
ESA will launch its MIMR microwave radiometer after the year 2000. MIMR operates at six
frequencies covering the 6.6 to 89 GHz range. Its spatial resolution will be better than that
of previous spaceborne radiometers (4 to 5 km at 89 GHz). The recently launched ERS-2
guarantees availability of C-band SAR data for several years. The Canadian RADARSAT will
be launched in September 1995. The SAR will provide C-band HH polarized data with a
substantially wider swath (up to 500 km) than the ERS-1 SAR sensors (100 km).
18.7 References
Anderson DL (1960) The physical constants of sea ice. Res Appl in Industry 13: 310-318
Arcone SA, Gow AG, McGrew S (1986) Structure and dielectric properties at 4.8 and 9.5
GHz of saline ice. J Geophys Res 91: 14281-14303
Assur A (1960) Composition of sea ice and its tensile strength. U.S. Army Snow and Ice and
Permafrost Res Establ, Wilmette, IL
Carsey FD, Barry RG, Weeks WF (1992) Introduction, Chapter 1 in: Carsey, F.D. (editor),
Microwave remote sensing of sea ice, American Geophysical Union Monograph 68, Washington,
DC, USA
Colbeck SC (1982) The geometry and permittivity of snow at high frequencies. Journal of
Applied Physics 53: 4495-4500
Cumming W (1952) The dielectric properties of ice and snow at 3.2 cm. Journal of Applied
Physics 23: 768-773
Debye P (1929) Polar Molecules, Dover, New York
Evans S (1965) Dielectric properties of ice and snow - a review. Journal of Glaciology 5:
773-792
Foster JL, HaIl DK, Chang ATC, Rango A (1984) An overview of passive microwave
snow research and results. Reviews of Geophysics and Space Physics 22, no. 2: 195-208
Foster JL, Chang ATC (1992) Snow cover, in: Guerney RJ, Foster JL, and Parkinson CL
(editors), Atlas of satellite observations related to global change, University Press, Cambridge
Gloersen P, Nordberg W, Schmugge TJ, Wilheit TT, Campbell WJ (1973) Microwave
signatures of first-year and multiyear sea ice. Journal of Geophysical Research 78: 3564-3572
Gray AL, Hawkins RK, Livingstone CE, Arsenault LD (1981) Seasonal effects on the
microwave signatures of Beaufort Sea ice, Proc. 15th International Symposium on Remote
Sensing of the Environment, pp. 239-257, Ann Arbor, Michigan, USA, May 11-15