Signatures of Forest Radar Images atVHF-band

BioGeoSAR’07

Overview

Airborne SAR system IMARK

Simultaneous radar and ground-based forest measurements

GPR sensing

Dependencies of backscattered signal on forest parameters

Conclusions

BioGeoSAR’07

Airborne SAR Complex IMARK

BioGeoSAR’07

Disposition of the Antennas on the Plane

BioGeoSAR’07

Main Features of the IMARK SAR Complex

Parameter Value

Frequency X L P VHF

Wavelength, cm 3.9 23 68 254

Polarization VV, HH, VH, HV

Resolution, m 4-68-10

10-15

15-20

Antennas: gain, dB 3014-17

14-17

9-11

Width in azimuth, deg 18 24 24 40

Width in elevation, deg 24 24 24 60

BioGeoSAR’07

Images Obtained by SAR System IMARK

L-band

P-band

VHF-band

Spas-Klepiki, Ryazanskaya Region

BioGeoSAR’07

The process of boring for the sampling of soil and the appearance of soil samples taken from different depths

BioGeoSAR’07

BioGeoSAR’07

Use of GPR for carrying out investigations on permittivity fluctuations in subsurface soil layers

BioGeoSAR’07

The examples of GPR measurements in particular points

BioGeoSAR’07

Theoretical estimation of backscattering from forest stand

1 2 3 4

Typical scattering mechanisms

Scattering from array of cylinderswith height distribution

1

2 0

3 0

24 0

( ; )

; exp 2 cos

; exp 2 cos

; exp 4 cos

trunk

trunk

trunk

trunk

S S

S S R j k h

S S R j k h

S S R j k h

10 15 20 250

0.2

0.4

0.6

0.8

Tree height, m

Bac

scat

teri

ng

inte

nsi

ty, m

-2 HHVV

BioGeoSAR’07

Scattering from layered medium with spatially inhomogeneous dielectric permittivity

Case 1: Layer 2 without large inhomogeneitiesCase 2: Layer 2 with large inhomogeneities(root system)

2

222 """

exp)()(

l

yyxx

l

zzrr

zNNN ff

Three layers: layers 1, 2 are inhomogeneous, layer 3is homogeneous.Correlation function of dielectric permittivity:

BioGeoSAR’07

Experimental dependencies of backscattered signal on stem diameter and distance between trees

0

5

10

15

20

0,10 0,15 0,20 0,25 0,30 0,35

diameter of tree steem, m

stre

ng

th o

f si

gn

al, r

elat

ive

mag

nit

ud

e

12

3 45

6

0

5

10

15

20

1.00 2.00 3.00 4.00 5.00 6.00 7.00

distance between trees, m

stre

ngth

of s

igna

l, re

lati

ve m

agni

tude

12

34

5

6

BioGeoSAR’07

0

5

10

15

20

12.00 14.00 16.00 18.00 20.00 22.00

height of trees, m

str

en

gth

of

sig

na

l, re

lati

ve

ma

gn

itu

de

12

3

45

6

0

5

10

15

20

200 250 300 350 400 450 500 550 600 650

biomass, m3/hа

stre

ng

th o

f si

gn

al, r

elat

ive

mag

nit

ud

e

1

2

3

4

5

6Experimental dependencies of backscattered signal on tree height and biomass

BioGeoSAR’07

Conclusions

Backscatter from forest at VHF band at HH polarization increases with the growth of biomass and tree diameter

Measurements conducted by ground penetrating radar confirm spatial variation of dielectric constant of the upper subsurface soil layer of forest

Large fluctuations of dielectric permittivity of the upper soil layer related with the presence of tree root system have significant importance in the formation of backscatter from forestland

Measurements conducted in different periods of time indicate the seasonal variation of backscatter from coniferous forest