10-Bands Ocean Color and Temperature Scanner
Feng Qi, Zheng Qin-Bo, Gong Hui-Xing
Shanghai Institute of Technical Physics Chinese, Academy of Science
500 Yutian Road, Shanghai 200083, P.R. China
Phone & fax: 86-21-65318330
Abstract
China is developing ocean observation satellite named HY-1. This satellite is scheduled to be launched in 2001 with meteorological satellite FY-1. 10-bands ocean color and temperature scanner and 4 bands CCD imager will be mounted on HY-1. In this paper we introduce the 10-bands ocean color and temperature scanner which has 10 bands from visible to thermal infrared and the ground resolution is 1.1Km at the nadir (orbit altitude =786Km). Four elements detector array is used for every band in order to improve detecting sensitivity and a "K" mirror is used to eliminate image rotating on the focal plane caused by 45o scanning mirror.
Introduction
HY-1 will be launched with FY-1 which altitude is 870Km and incidence is 98.8°.
Because the decending crossing time of FY-1 is about 8.35 a.m., so it is not good
for ocean observation. Therefore, HY-1 will change its altitude from 870Km to 798Km in order to improve the illuminance of the earth surface. HY-1 will move round the earth 14.3 cycles one day. As the reflectance of ocean is very low, four elements detector array is used to eliminate image rotating on the focal plane caused by 45o scanning mirror. There are four scan lines along the flying direction at the same time while the scanning mirror rotating one cycle. Table 1~table 2 list some important parameters of the 10-bands ocean color and temperature scanner.
Table 1 main Characters of the scanner
| Ground resolution (nadir) |
1.1 Km |
| FOV |
±35.2o(1024 pixels per line) |
| Polarization sensitivity |
£5% |
| Center wavelength accuracy |
£2nm |
| Quantization |
10bit |
| Aperture |
200mm |
| Weight |
50 kilograms |
| Calibration accuracy |
5%~10%(visible, near infrared)
1K (thermal infrared) |
| Life time |
2 year |
Table 2 Signal to noise ratio and dynamic range
| Band (mm) |
Input power* |
Signal to noise ratio |
Dynamic range** |
| 0.402~0.422 |
9.10 |
349 |
0~40% |
| 0.433~0.453 |
8.41 |
472 |
0~35% |
| 0.480~0.500 |
6.56 |
467 |
0~30% |
| 0.510~0.530 |
5.46 |
448 |
0~28% |
| 0.555~0.575 |
4.57 |
417 |
0~25% |
| 0.660~0.680 |
2.46 |
309 |
0~20% |
| 0.730~0.770 |
1.61 |
319 |
0~15% |
| 0.845~0.885 |
1.09 |
327 |
0~15% |
| 10.3~11.4 |
|
NE?T=0.2K(300K) |
200~320K |
| 11.4~12.5 |
NE?T=0.2K(300K) |
200~320K |
* Unit: mW.cm-2 .mm-1.Sr-1
**The dynamic range of band1~band8 means the equivalent reflectance of one solar constant |
