Flevoland, The Netherlands


Titles of Investigations:

I.  A Study of the Potential of Multi-Component SAR Imagery for 
Agricultural and Forestry Studies

II.  Multi-Frequency, Multi-Polarization External Calibration 
of the SIR-C/X-SAR Radars

Principal Investigators:

I.  Dr. Ralph Cordey   Cordey wants to be deleted from this site.
  Marconi Research Centre

II.  Dr. Anthony Freeman
  Jet Propulsion Laboratory

Site Description:

 The Flevoland test site is in a polder of 30 by 60 km located 
in the center of the Netherlands; the polder was reclaimed from 
a former sea in 1968.  The topography is almost perfectly flat, 
and the general altitude is three meters below sea level.  
Because of its short history, the landscape of the polder is quite 
simple, which is an advantage in remote sensing images interpretation.  
It mainly shows straight roads, farm houses, agricultural fields, 
forest areas, and only a few urban areas.  The forest areas 
consist of young deciduous trees planted in a regular row pattern.  
The agricultural fields are cultivated by private as well as 
state farms.  The fields cultivated by state farmers are 
large compared to fields cultivated by private farmers.  
The state farms are meant to prepare the "naked sea bottom" for 
full agricultural use by cultivating them on a non-commercial basis.  
After this initial phase, the fields will be given to private farmers.  
By 1996, all fields now owned by the state farms will be divided 
among private farmers, implying smaller agricultural fields.

 The areas of main interest are found in the southern part of 
the polder.  They include an agricultural area and a forested area, 
each measuring approximately 10 by 10 km.  The agricultural area 
is centered around the coordinates 52.33° N and 5.45° E and 
mainly contains fields cultivated by state farmers.  The forested area 
is centered around the coordinates 52.31° N and 5.49° E.

 To compare the results from this typical young forest (³Horsterwold²) 
with an older forest , a second forest site (³Speulderbos²) has 
been chosen on neighboring "old" land.  Speulderbos  is located 
on an ice-pushed ridge with an altitude varying from 40 to 55 m 
above sea level.  It is centered around the coordinates 52.16° N 
and 5.67° E and contains both deciduous and coniferous trees.  
The ages of the deciduous trees are up to 150 years old.

 The test site has been used extensively since 1984 for various 
remote sensing experiments and was a part of the SIR-B experiment.  
More recently, it was used in the Maestro 1989 and the 
MAC Europe 1991 campaigns, during which it was monitored several 
times by the NASA/JPL SAR.

Objectives:

I.  a) The objective of this study is to develop methods to fully 
exploit multi-component SAR datasets of agricultural and forested areas.

II.  a) Assess the accuracy at which the SIR-C/X-SAR standard data 
products can be calibrated.

  b) Study the cross-calibration between three independent 
multi-polarization systems:  SIR-C, the NASA/JPL DC-8 SAR, 
and the University of Michigan ground-based polarimetric scatterometer.

  c) Evaluate the calibration ³stability² of the SIR-C/X-SAR.

  d) Develop a cost-effective calibration plan which includes 
development of inexpensive polarimetric active calibrators.

Field Measurements:

Flevoland will be used as a calibration site for the European 
Remote Sensing experiment (ERS-1).  It is likely that corner 
reflectors deployed for ERS-1 will remain at the site for use 
by SIR-C/X-SAR calibration.

I.  a) Carry out simultaneous ground truth measurements to 
provide environmental soil, crop, and forest parameters.

  b) Provide precise calibration of the SAR images using a 
combination of ground-based scatterometers and active and 
passive radar targets.

II.  a) Deploy inexpensive trihedral corner reflectors to 
characterize co-polarized channel imbalance in magnitude 
and phase over an area wider than that covered by the active 
calibrators in the primary calibration area. 

Crew Observations:

1) Crew Journal: Describe the weather conditions and cloud cover, 
forest canopy, and agricultural activity at the site.

2) Cameras: Hercules and Hasselblad will be used to photograph 
the forests and agriculture at the site.

Coverage Requirements:

The minimum coverage requirements for this supersite are 
four (4) passes, preferably ¾ 48°.

Anticipated Results:

I.  a) Test the validity of backscatter models developed 
from ground and aircraft measurements for representing measurements 
from a multi-polarization spaceborne SAR.

  b) Development of improved processing tools for extracting 
information from multi-component SAR images over agricultural 
and forested areas.

  c) Assessment of the effectiveness of a variety of ground-based 
techniques for calibrating spaceborne SAR images.

  d) Determination of the optimum SAR measurement parameters and 
preliminary techniques for monitoring and classifying agricultural 
and forested areas.

II.  a)  Full polarimetric end-to-end characterization of the 
SIR-C/X-SAR system in the primary calibration target area 
within the limitations of instrument accuracy.

  b) A better understanding of polarimetric calibration of 
space-borne microwave synthetic aperture radar.