Misi EEE BB RR ER 
| MERLO: ML s 
intervals (cloud cover permitting) for the Great Lakes and the Bay of Fundy 
- Nova Scotia coastal waters. Occasionally temperatures of other water bodies 
(e.g. Lake Winnipeg, Hudson Bay) are monitored in support of special programs. 
NOAA SATELLITE SYSTEM 
The primary mission of the NOAA satellite program is to provide daily 
globe-wide meteorological information for weather forecasting. Designed for 
uninterrupted monitoring, the system maintains two operational space platforms. 
When one satellite nears the end of its operational life span a new one is 
launched. At present the two operational satellites are NOAA-6 and NOAA-7. 
The orbital characteristics, sensor types and data transmission modes of 
the NOAA satellites are described briefly below. Complete information on the 
satellite system is provided by NOAA Technical Memoranda: NESS 60, by Fortuna 
and Hambrick (1974), and NESS 95, by Schwalb (1978). 
Orbital Characteristics 
  
The satellites operate in sun-synchronous near-polar orbits at altitudes 
of 833 + 90 km. Orbital inclination is between 98 and 99 degrees, orbital 
period is about 102 minutes. The satellites orbit the earth 14 times per day, 
overflying the mid-latitude regions twice in a 24 hour period. 
Sensors 
The satellites are equipped with Advanced Very High Resolution 
Radiometers (AVHRR). Through the years the number of sensors carried by the 
satellites has been increased from two, on board the earlier members of the 
series, to five on NOAA-7. The AVHRR sensors operate in the following spectral 
regions (channels): 
Channel No. Range (yum) 
1 0.555 0.68 
2 0.225 7 1.10 
3 3.55 + 3.93 
4 10:5 = fl 5 
5 11.5 mit 2-5 
The sensors scan continuously at 360 lines per minute while rotating 
about an axis aligned in the direction of travel of the spacecraft. The field 
of view of the sensors is 1.3 milliradians. The radiation detected over the 
earthward portion of a scan is split into 2048 elements (pixels). A pixel 
comprises the radiation intensity from a km area of the earth's surface at 
satellite sub-point. Away from the sub-point pixels represent progressively 
larger rectangular areas. 
DATA PROCESSING 
The satellites transmit lO-bit digital data. In addition to the 
radiation intensities detected in the different channels, the data stream 
contains sensor calibration counts and other elements of information. 
Reception of data commences when the satellite rises above the local horizon of 
the receiving station. The data are recorded on disk, and subsequently smaller 
blocks of data, covering selected areas, are extracted and transferred to 
magnetic tape for later analysis and archiving. 
718 
CC 
1C 
me 
X 
-—b . /ÀÁ"7. s