Keywords: Meteorological satellite,
program, application system, international
collaboration.
Abstract
China has been making her unremitting
efforts on pushing her meteorological
satellite program and building up the
meteorological satellite as well as data
application systems. The meteorological
satellite program of China consists of two
major systems: Polar-orbiting system and
geostationary system. The main objectives
of the program are to establish, with
combination of polar and geostationary
orbits, a comprehensive operational
meteorological satellite system as well as
data application systems around the turn of
the century, in order to meet the needs on
various aspects in China, and enhance the
capability of participating international
collaboration.
1. Introduction
Meteorological satellites have become an
irreplaceable weather and ocean observing
tool in China. These satellites are monitoring
major natural disasters and improving the
efficiency of many sectors of our national
economy. Therefore, meteorological satellite
has been regarded as a kind of applied
satellite with notable social and economic
benefit among man-made satellites. It is not
feasible nowadays to ignore the space
derived data in the field of meteorology,
hydrology, agriculture as well as disaster
monitoring in China, such a big agricultural
country. For this reason, China is making
her unremitting efforts on building up the
meteorological satellite system and data
application system.
The meteorological satellite program of
China consists of two major systems: Polar
orbiting and geostationary series. The main
objectives of the program are to establish,
with combination of polar and geostationary
orbits, a comprehensive operational
meteorological satellite system as well as the
ground monitoring and application data
system around turn of the century, in order
to meet the needs on various aspects in
China, and enhance the ability to participate
international collaboration. The Ministry of
Aerospace of China takes the responsibility
for the space segment, while China
Meteorological Administration is in charge
of the ground segment.
In China, meteorological satellites are
named simply as Feng-Yun series,
abbreviated as FY-series. The Chinese
words Feng-Yun in English standards for
"Winds and Clouds". We use the FY- odd
number ,i.e. FY-1,FY-3, etc. to name the
polar orbiting satellite series, and FY-even
number, i.e.FY-2, FY-4, etc. to the
geostationary series.
2. China's first generation of polar
orbiting meteorological satellites: FY-1
According to the present plan, China's first
generation of polar orbiting meteorological
satellite system, FY-1, will consist of four
satellites, as well as the corresponding
ground data acquisition, processing amd
application systems.
2.1 The FY-1A and FY-1B
With the increasing awareness of the
importance and notable benefits of
meteorological satellites in 1960’s, China
has initiated her first polar orbiting
meteorological satellite project FY-1 series
in 1977. The FY-1A and FY-1B were
designed and manufactured by the Ministry
of Aerospace of China according to the
requirement specified by China
Meteorological Administration (CMA). The
satellite is a hexahedron of 1.4×1.4×1.2(in
height) and the weight is 750 kg. The two
solar cell arrays mounted on both sides of
the main body make the total length of the
satellite 8.6 meters. The attitude control of
the satellite is three-axis stabilized with a
precision of no less than 1 degree in all three
axis. FY-1A and FY-1B operated in a sun-synchronous
orbit at an altitude of 901 km
with an orbital period of 102.86 minutes.
The inclination angle is 98.9
° and the
eccentricity is less than 0.005. Table 1 gives
the main orbit parameters of the FY-1A and
FY-1B satellites
Table 1. Orbit parameters of FY-1A/B Meteorological satellites
| Satellite |
FY-1A |
FY-1B |
| Launch date |
September 9,1988 |
September 3, 1990 |
| Orbit |
Sun-synchronous |
Sun-synchronous |
| Altitude (km) |
901 |
901 |
| Period (minutes) |
102.86 |
102.86 |
| Inclination (degrees) |
99.0 |
98.9 |
| Eccentricity |
<0.005 |
<0.005 |
| Descending Node(LST) |
03:30 |
07:50 |
| Attitude Control |
Three-axis stabilized |
Three-axis stabilized |
The main meteorological payload on board
FY-1A and FY-1B satellites are five channel
Visible and Infrared Radiometers, similar to
AVHRR instrument but with different
channel wavelengths. Table 2 gives the
channel characteristics of the radiometer on
board FY-1A and FY-1B satellites
Table 2. The channel characteristics of radiometers onboard FY-1A and FY-1B
| Channel |
Wavelength(µm) |
Primary Use |
| 1 |
0.58-0.68 |
Cloud and surface image, vegetation |
| 2 |
0.725-1.1 |
Cloud and surface image, vegetation |
| 3 |
0.48-0.53 |
Ocean color |
| 4 |
0.53-0.58 |
Ocean color |
| 5 |
10.5-12.5 |
Diurnal cloud and surface image, SST |
The FY-1 observation data are disseminated
in three modes: High Resolution Picture
Transmission (HRPT), Automatic Picture
Transmission (APT), and Delayed Picture
Transmission (DPT). For HRPT and APT,
direct readout services are provided during
satellite operations with data format
compatible with NOAA satellites. The DPT
data are cloud images for selected areas over
the world.
The ground segment of FY-1 consists of
three ground stations located in Beijing,
Guanzhou and Urumuqi respectively and a
Data Processing Center (DPC) at National
Satellite Meteorological Center in Beijing.
The data received at the ground stations are
relayed in real time to the Beijing DPC for
processing, distributing, and archiving.
Derived products from the DPC include
cloud image masaics in a variety of
projections, meteorological parameters such
as sea surface temperature, clout top
temperature and total water vapor; regional
environmental parameters such as vegetation
index, snow cover, sea ice, land cover, etc.
All raw data and products are archived on
digital tapes. Images are broadcast via TV to
the public.
2.2 The Status of FY-1A and FY-1B
FY-1A was launched successfully on
September 7, 1988 by launch Vehicle of
Long March-4. The spacecraft went into the
predicted orbit accurately and started to
make observations at the same day. The
pictures from the visible channels were quite
good, and the signal to noise ratios was
higher than the designed ones. Unfortunately,
it worked only for 39 days and did not fulfill
its expected lifetime because the satellite
attitude was out of control. However, during
the flight of FY-1A the performance and
specifications of the payload and the satellite
subsystems were examined. There were two
problems with FY-1A: satellite attitude was
out of control after 39 days; and water vapor
contamination on the infrared detectors,
which was the main reason of the IR signal
loss.
The second spacecraft, FY-1B was launched
after two years by Lang March-4 rocket
successfully into predicted orbit on
September 3, 1990. Although the overall
design of FY-1B is almost the same as FY-1A,
the quality of FY-1B was really an
improvement on FY-1A's, both on accuracy
and stability of satellite attitude control and
on scan radiometers. This satellite made
successive observations for half a year.
However, the same problem, the attitude out
of control appeared again. After rescuing by
ground commanding, the satellite was
brought back and made observations again
until late 1992 when the rescuing was give
up. This indicated that there are some
problems on reliability remained to be
improved further.
