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NOAA Polar Satellite Information

In May 1998, a new series of operational environmental satellites began with the launch of NOAA-K. NOAA-K, L, and M will be the successors to the NOAA satellite series ended with NOAA-14.

These new satellites carry a series of instruments which have been modified and improved from previous NOAA-series satellites still in orbit and operational.

The Advanced Very High Resolution Radiometer (AVHRR/2) has been modified. The new instrument, AVHRR/3, adds a sixth channel in the near-IR, at 1.6um. This will be referred to as channel 3A and will operate during the daylight part of the orbit. Channel 3B corresponds to the previous channel 3 on the AVHRR/2 instrument, and will operate during the night portion of the orbit. The operational scheduling of the channel 3A/3B switching is posted elsewhere on the NOAASIS web site. A flag (Word 7, Bit 10) of the telemetry will indicate which of the two channels is operating. Splitting channel 3 in this way maintains the HRPT data format which was designed to handle five AVHRR channels. Channels 3A and 3B are output at the same telemetry locations.

Automatic Picture Transmission (APT) users will receive the AVHRR/3 channel 3A the same as channel 3B, with an ID wedge equivalent to grey scale wedge 3.

The AVHRR/3 visible channels (1, 2, and 3A) all have "split gains" or "dual slopes" that require the use of two calibration equations per channel, where previously one would suffice. The split gains, if effect, increase the sensitivity at low light/energy levels. The prime reason for these changes are to improve ice, snow and aerosol products produced from the visible channel data. The visible channel ramp voltage calibrations will also have dual slopes.

The Microwave Sounding Unit (MSU) and Stratospheric Sounding Unit (SSU) instruments have been replaced. NOAA-K was launched with Advanced Microwave Sounding units AMSU-A1, AMSU-A2 and AMSU-B. The AMSU-A is a 15-channel microwave radiometer in two separate units. For AMSU-A1,-A2, the word 0001H will be used as fill data most of the time in the telemetry stream. The new AMSU data is expected to provide improved temperature and humidity soundings. Additionally, window channels 1, 2 and 15 will provide information on precipitation, sea ice and snow cover. The AMSU-B is a five-channel microwave radiometer; three of the channels are centered on the 183.31 Ghz water vapor line. The other two channels are at 89 Ghz and 150 Ghz.

The Solar Backscatter Ultraviolet Radiometer (SBUV) is carried in satellites with an afternoon orbit. NOAA-K was launched into a morning orbit but carries the SBUV/2, which has only minor changes from similar instruments carried on previous spacecraft.

While NOAA-L and -M will be tested in an afternoon orbit configuration, it will be capable of being launched as a morning or afternoon spacecraft to meet operational needs.

The new High Resolution Infrared Radiation Sounder (HIRS/3) will have the calibration sequence changed. On HIRS/2, the calibration mode required the use of three calibration targets (space view, cold target, and warm target). On HIRS/3, the cold target will not be routinely used in the calibration sequence, resulting in one additional scan line of Earth data (38 Earth scans per 256 second cycle).

The Argos Data Collection System (DCS) aboard the NOAA polar orbiting satellites was improved for NOAA-K. The DCS/2 will have an increased data transmission rate (from 1200 to 2560 bits per second) and the on-board data recovery units (DRUs) will be increased from four to eight.

An improved Space Environment Monitor (SEM-2) has added in-flight calibration capabilities and improved particle detection. The Total Energy Detector (TED) will measure to a lower energy (0.05 keV versus 0.3 keV on NOAA-J). The Medium Energy Proton/Electron Detector (MEPED) has a fourth, omnidirectional, proton sensor for greater than 140 Mev. More data will will be included in the telemetry stream.

The Search and Rescue Processor (SARP) has added capabilities for the handling of distress messages, as well. The number of Data Recovery Units has been increased from two to three.

With the new instruments, data formats will be changed slightly. Within the HRPT Minor Frame format, the first Minor Frame will be TIP data, the second Minor Frame will be spare, and the third Minor Frame will be the AMSU-A1, -A2, and B data.

Within the TIP Minor Frame (orbital mode format), the deletion of the MSU and SSU instruments will make available several words. DCS/2 data will now be contained in additional words 18, 19, 24, 25, 32, 33, 40, 41, 44, 45, 61, 68, 69, 76, 77, 86 and 87. HIRS data will move from words 14/15 to 16/17. Word 102 will be a spare.

As noted above, the third Minor Frame will contain only AMSU data. The AMSU information processor (AIP) inputs data from the three AMSU instruments and the TIP. This Minor Frame will contain 208 words. In summary, words 8 through 33 will contain AMSU-A1 data, words 34 through 47 will contain AMSU-A2 data, and words 48 through 97 will contain the AMSU-B data.

Detailed information about the NOAA-K,L,M instruments, data formats, calibration and similar technical characteristics of the spacecraft are contained in the NOAA-KLM User's Guide which is available on-line. A file of this document is also available for downloading via ftp; details can be found at the User's Guide site.

Revised: 30 May 2001