Backscattering properties of boreal forests at the C- and X-bands

The backscattering properties of boreal forests are studied using empirical airborne and spaceborne radar data from Finland. Airborne measurements were carried out in the summer of 1992 by the HUTSCAT scatterometer at the Teijo test area in southern Finland. The HUTSCAT scatterometer is an eight-channel helicopter-borne profiling radar operating at the C- and X-bands. The ranging capability of the HUTSCAT scatterometer was employed in the semiempirical modeling of forest backscatter. The backscatter profile information was used in the analysis of the canopy transmissivity and the canopy backscattering coefficient by distinguishing backscattering contributions from the canopy and the ground. Additionally, ERS-1 C-band satellite SAR measurements were obtained for the Teijo test area and for the reference test area in Sodankyla in northern Finland. The radar results were compared with operational ground-based forest assessment data on forest compartments (stands) of the area. The key parameter investigated was the stem (bole) volume per hectare. The results obtained show the behavior of the canopy transmissivity and the canopy backscatter as a function of stem volume (directly related to the forest biomass). The influence of seasonal and diurnal changes on, and the effects of the changes in soil moisture to the backscattering coefficient were also investigated. >

[1]  Juha Hyyppä,et al.  A helicopter-borne eight-channel ranging scatterometer for remote sensing. I. System description , 1993, IEEE Trans. Geosci. Remote. Sens..

[2]  F. Ulaby,et al.  Vegetation modeled as a water cloud , 1978 .

[3]  Martti Hallikainen,et al.  Effect of land-cover type and season in microwave remote sensing of snow , 1993, Proceedings of IGARSS '93 - IEEE International Geoscience and Remote Sensing Symposium.

[4]  John Richards,et al.  L-Band Radar Backscatter Modeling of Forest Stands , 1987, IEEE Transactions on Geoscience and Remote Sensing.

[5]  P. Hakkila,et al.  Wood density survey and dry weight tables for pine, spruce and birch stems in Finland [Pinus sylvestris, Picea abies, Betula pendula, Betula pubescens] , 1979 .

[6]  D. H. Hoekman,et al.  Radar remote sensing data for applications in forestry. , 1990 .

[7]  Pekka E. Kauppi,et al.  Impact of Forests on Net National Emissions of Carbon Dioxide in West Europe , 1993 .

[8]  Gautam D. Badhwar,et al.  The use of a helicopter mounted ranging scatterometer for estimation of extinction and scattering properties of forest canopies. II. Experimental results for high-density aspen , 1988 .

[9]  F. Ulaby,et al.  Microwave Dielectric Behavior of Wet Soil-Part II: Dielectric Mixing Models , 1985, IEEE Transactions on Geoscience and Remote Sensing.

[10]  Martti Hallikainen,et al.  Diurnal variation of backscattering properties of pine trees at C- and X-band , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[11]  Fawwaz Ulaby,et al.  Microwave Dielectric Spectrum of Vegetation - Part II: Dual-Dispersion Model , 1987, IEEE Transactions on Geoscience and Remote Sensing.

[12]  M. C. Dobson,et al.  Spatial and temporal variation of the microwave dielectric properties of loblolly pine trunks , 1991, [Proceedings] IGARSS'91 Remote Sensing: Global Monitoring for Earth Management.

[13]  Kamal Sarabandi,et al.  An empirical model and an inversion technique for radar scattering from bare soil surfaces , 1992, IEEE Trans. Geosci. Remote. Sens..

[14]  Paul J. Kramer,et al.  Physiology of Woody Plants , 1983 .