Very high resolution scanning radiometer on FY-1 meteorological satellite and its operation
performance in orbit
Kuang Dingbo, Gong Huixing, Zheng Qinbo
Shanghai Institute of Physics, Academia Sinica
Abstract
This paper describes the operation principle of the very high resolution scanning radiometer on "FY-1" meteorological satellite, the characteristics of its output imagery, the quality of the imagery, acquired after entering the orbit and measuring results of the operation performance in orbit.
Purpose of the mission
The "FY-1" meteorological satellite is the first satellite for environment remote sensing ever launched by China. Its main purpose is to acquire global cloud picture day and night and carry out ocean color remote sensing experiments. The satellite entered accurately the sun synchronous orbit on Setp. 7th, 1988 with a high of 901 km, inclined angle 99.10 and period 102.8 min.
The very high resolution scanning radiometer is the main detecting instrument of the satellite and Fig. 1 shows its out appearance. With five channels the scanning radiometer can obtain simultaneously five spectral bands data of objects.
| Spectral band |
Detected object |
| Ch1 : 0.58~0.63mm |
Visible cloud, vegetation, oceansilt, snow cover |
| Ch2: 0.725~1.1mm |
Visible cloud,vegetation,demarcation between water and land, snow cover |
| Ch3: 0.48~0.53mm |
Chlorophyll at sea. |
| Ch4: o.53~0.58mm |
Chlorophyll at sea and silt |
| Ch5: 10.5~12.5mm |
IR cloud, target temperature |
In which Ch1, Ch2, Ch5 are used to take pictures of visible and infrared clouds for weather forecast. The data measured from Ch1 and Ch2 vegetation parameter and differentiate cloud and snow. Ch4 and Ch5 are used for observation of ocean cloud to obtain distribution of chlorophyll with medium and high concentration at sea. The thermal IR channel of the scanning radiometer has the ability of radiation response calibration in flight and can measure quantitatively
equivalent blackbody temperatures of targets (such as sea surface, cloud top etc) the image data can also be used for monitoring piled snow, sea ice and vast area of floods and other disasters.
The imagery information obtained by the scanning radiometer is transmitted in real time to the areas covered by the satellite in two forms. The HRPT image signals containing five channel's digital image signals with ground resolution of 1.08 km at nadir are modulated and transmitted at a frequency of 1700 MHz. The APT image signals containing two channel's analog image signals after having geometric calibration and resolution reduction proceeding, are modulated and transmitted at a frequency of 137 MHz. The image signal format of both HRPT and APT is the same as that of American NOAA and the various ground receiving stations for NOAA are available for FY-1 satellite.
With a width of 3235 KM. of HRPT and APT images, the satellite circles the earth 14 times per day and the visible / near IR channel covers the whole globe every 254 hours and the coverage period of the thermal IR channels is 12 hours.
Fig. 1 Outer apperance of the very high resolution scanning radiometer
