THE MERIT OF JERS-1 DATA IN ADDITION TO ERS-1 DATA FOR LAND COVER MONITORING 
J.G.P.W. Clevers (1), H. Kramer (2), H.J.C. van Leeuwen (3) and D.H. Hoekman (4) 
(1) Dept. of Landsurveying and Remote Sensing, Wageningen Agricultural University, 
P.O. Box 339, 6700 AH Wageningen, The Netherlands 
(2) DLO - Winand Staring Centre for Integrated Land, Soil and Water Research (SC-DLO), 
P.O. Box 125, 6700 AC Wageningen, The Netherlands 
(3) Synoptics BV, P.O. Box 117, 6700 AC Wageningen, The Netherlands 
(4) Dept. of Water Resources, Wageningen Agricultural University, 
Nieuwe Kanaal 11, 6709 PA Wageningen, The Netherlands 
Commission VII, Working Group 1 
KEY WORDS: SAR Imagery, Land Use, Agriculture, Forestry, Monitoring 
ABSTRACT 
The applicability of the JERS-1 L-band SAR for land applications was evaluated in addition to the use of the ERS-1 
(C-band). For operational applications, satellite data should be used for land cover classification, parameter 
estimation and the monitoring of vegetation and soils. The JERS-1 satellite is a new satellite, offering new 
features that must be tested in comparison to other satellite data. First of all, the JERS-1 combines an optical and 
a microwave sensor. Secondly, the microwave sensor is an L-band SAR having longer wavelengths than the C- 
band SAR of the ERS-1, thus offering interesting possibilities for parameter retrieval and monitoring of vegetation 
and soils. 
In studying time series of radar backscatter from JERS-1 and ERS-1 for agricultural crops, it was found that the 
dynamic range of JERS-1 time series during the growing season was not as large as found before for L-band in 
airborne campaigns and it was less than the one of ERS-1 time series. The backscatter signatures of JERS-1 
during the growing season were difficult to compare with those of ERS-1 during the growing season because of 
the very limited number of JERS-1 observation dates available. 
Using three JERS-1 images, a multitemporal object-based classification of agricultural crops was performed. The 
classification results were compared with a composed digital reference map of the research area. When 
comparing the results of a multitemporal per field classification based on ERS-1 data with the results for JERS-1 
data, varying results were obtained. Some crops were classified more accurately using JERS-1 data, other crops 
were classified worse in comparison to the use of ERS-1 data. For instance, grassland and potatoes were 
classified most accurately using ERS-1 data. On the contrary, sugar beet, maize and barley were classified more 
accurately using JERS-1 data. 
In forestry, results showed that JERS-1 is better suited to discriminate forest species than ERS-1. A multi- 
temporal approach, i.e. at least one observation in winter and one in summer/spring, is recommended. A visual 
interpretation of images revealed that the broad discrimination between deciduous and coniferous species is well 
possible with a single L-band summer image. 
1. INTRODUCTION The JERS-1 satellite is a new satellite, offering new 
features that must be tested in comparison to other 
Using remotely sensed data for land cover mapping satellite data. First of all, the JERS-1 combines an 
  
often implies the use of optical data. Several satellite 
sensors are available (e.g. Landsat TM, SPOT-XS) but 
due to weather conditions it is not always possible to 
get data for a specific area during a specific period of 
time. The availability of microwave data (e.g. ERS-1, 
JERS-1) is not restricted by weather conditions. 
The application of ERS-1 SAR data (C-band) for map- 
ping land cover was investigated by Nieuwenhuis & 
Van Rooij (1994). With images taken during the gro- 
wing season of 1992 they showed the applicability of 
such images. The optimal classification results were 
obtained with 8 images well distributed in time. With a 
decrease of the number of images the discrimination 
between crops decreased. 
optical and a microwave sensor. Secondly, the micro- 
wave sensor is an L-band SAR having longer wave- 
lengths than the C-band SAR of the ERS-1, thus offe- 
ring interesting possibilities for monitoring and parame- 
ter retrieval of vegetation and soils. In this study, we 
tried to evaluate the applicability of the JERS-1 for 
land applications in comparison to the use of the ERS- 
1 (C-band). 
For. the JERS-1 application research (classification, 
parameter estimation, monitoring), actual field data 
(ground truth) was collected during the 1993 growing 
season (e.g. crop type, crop cover, crop reflectance, 
soil moisture). From November 1992 until November 
1993, as many as possible microwave and optical 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996