JERS-1 OPSの放射輝度観測性能の評価 Examination of Radiometric Observation Capability by JERS-1 OPS
This is a study to examine the observation capability of radiometric intensity by JERS-1 OPS. Several ground targets with different spectral characteristics as large as to be identifiable by OPS such as bare soil areas, grass areas and ponds were selected. The spectral characteristics of the ground targets and the irradiances were measured on the ground at the same time with JERS-1 overpass. The measurements on the ground were carried out twice, one in winter and the other in summer. The radiometric intensity of the ground targets at an altitude of the satellite were calculated using the atmospheric transmittance and the path radiances of the optical path from the ground surface to the satellite, which were estimated by LOWTRAN 7. On the other hand, Digital Numbers of the ground targets were obtained from the OPS images acquired at the same dates with the measurements on the ground and they were transformed to radiances using the conversion equation provided by NASDA.<BR>The observation capability of radiometric intensity by OPS was examined by comparing the calculated radiances with the observed radiances by OPS of the ground targets for each band in each test case. Both values were plotted in graphs. Most of the points were generally dispersed and not included in the coincidence area deffined as an range within±10% from the line of 45' in the graphs. But there may be errors of about 12% for the calculated radiances and 2% for the observed radiances. Considering that the coincidence area is an area within ±24% from the line of 45°, about 80% of the points were included in the coincidence area. From the above, it may be said that the differences between the observed radiances by OPS and the calculated radiances of the ground targets may be included in the range within ±10% with an accuracy of about 80%.<BR>The winter case showed a better agreement than the summer case, why the estimation of the atmospheric transmittance and the path radiance are considered to be closer to the reality in winter than in summer. It is better to carry out the evaluation test in winter for the examination of radiometric observation capability by optical sensors.
- 日本リモートセンシング学会誌 = Journal of the Remote Sensing Society of Japan
日本リモートセンシング学会誌 = Journal of the Remote Sensing Society of Japan 19(1), 64-74, 1999-03-31
The Remote Sensing Society of Japan