Multi- Seasonal Analysis of SAR Data for Agriculture
3. Results
3.1 konsen-plateau
This area is located in the north -eastern part of Hokkaido. The temperature in this area is low for growing crops and agricultural land use of this area is mostly grass for livestock. JERS-1/SAR and LANDSAT/TM images acquired almost at the same time of years in April, June and August, and they are indicated as photo 1. In LANDSAT IMAGE Acquired in April, bright parts represent grasses and evergreen forests, and dark parts represent urban areas, bare soils and deciduous forests. In LANDSAST images acquired in June and August, bright parts represent forest and grassland, and dark parts represent urban areas , bare soils and just after cutting grassland.
Photo 1. JERS-1/SAR and LSNDSAT/TM images in Konsen-plateau
AS for JERS-1/SAR images, three images of different times are almost same . in these images, bright parts are forests and u]urban area, and dark parts are grasses and bare soil. While it is very difficult to distinguish forests from grasses using SANDSAT/TM data, it is easy to separate the two things using JERS-/SAR.
Using JEERS-1/SAR and KANDSAT/TM data , we can classify grasses, evergreen forests, deciduous forests, urban areas, bare soils and deciduous forests.
We tried to extract agricultural area containing grasses and bare soils in this region using
JERS-1/SAR data. First, we performed speckle noise reduction using filter treatment, and then we picked up agricultural area as low digital number parts by level slice method. From the observation of JERS-1 data, it can be concluded that L-band microwave passes through grass body, and scatters on earth.
Back scattering coefficients in Konsen-plateau are calculated and indicated in fig.1. Forest if the highest, second id urban area, and the lowest is grassland. We can not detect any seasonal changes.
Figure 1 Back Scattering Coefficient of JERS/SAR on Konsen Plateau
Table 2 List of remote sensing data used in this study
| Area name |
sensor |
Acquisition time |
| Konsen-plateau (Hokkaido)
| JERS-1/SAR
LANDSAT/TM |
1992/04/15
1993/04/02
1993/06/30
1993/08/31
1992/04/09
1991/04/23
1991/06/26
1990/08/13 |
| Tokachi plain (Hokkaido) |
JERS-1/SAR
ERS-1/AMI-IMAGE
LANDSAT/TM |
1992/06/01
1992/07/15
1992/08/28
1992/10/23
1992/06/02
1992/08/11
1992/04/09
1987/06/22 |
| Ishikari plain (Hokkaido) |
JERS-1/SAR
ERS-1/AMI-IMAGE
LANDSAT/TM |
1992/02/04
1992/08/31
1992/05/20
1992/10/14
1992/07/29
1987/06/22 |
3.2.Tokachi plain
This area is located in the eastern part of Hokkaido. The area is mostly comprised of crop field and no paddy. The crops are winter wheat, sugar beet, soy bean, kidney bean, corn potato etc. JERS-1/SAR data were acquired in June, July August and October;
ERS-1/SAR data were acquired in June and August.
In four JERS-1/SAR images, we can detect some difference caused by the soil surface change. Distinctive difference between the two WES-1/SAR images can be observed. In early June, most areas appears very dark and small parts very bright, because there are very small crop plants or no crop in the agricultural field. Plowing direction that is perpendicular to that of microwave radiation was recognized as bright line. In August,
Most areas are bright because crops grew large. We can detect the edge of plateau in ERS-1/SAR images easily while it is difficult to do so in LANDSAT/TM image.
