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TRMM TMI Scan Status
Name Format Values Description
Missing 1-byte integer Value and meaning Indicates whether information is contained in the scan.
Validity 1-byte integer Bit and meaning A summary of status modes.
QAC 1-byte integer 0: No decoding error occurred. The Quality and Accounting Capsule of the Science packet as it appears in Level-0 data.
1-byte integer Bit and Meaning A summary of geolocation quality in the scan.
Data Quality[9] 9 x 1-byte integer - A quality of Channel Data for given channel on given scan line is the percentage of pixels whose value are within the acceptable range listed in the metadata.
Current Spacecraft
1-byte integer Value and Meaning Current spacecraft orientation.
Current ACS Mode 1-byte integer Value and Meaning Current ACS mode.
Yaw Update Status 1-byte integer 0: Inaccurate
1: Indeterminate
2: Accurate
Yaw update status.
TMI Instrument Status 1-byte integer Bit and Meaning TMI instrument status.
Orbital Number
4-byte float   The orbit number and fractional part of the orbit at Scan Time.
The orbit fraction part is calculated as:
(Time-Orbit Start Time)/(Orbit End Time-Orbit Start Time)

Value and Meaning of Missing
Value Meaning
0 Scan data elements contains information
1 Scan was missing in the telemetry data
2 Scan data contains no elements with rain

Bit and Meaning of Validity
Bit Meaning if bit=1 Note
0 Spare (always 0) Validity is a summary of status modes. If all status modes are
routine, all bits in Validity = 0. Routine means that scan data
has been measured in the normal operational situation as far as
the status modes are concerned. Validity does not assess data or
geolocation quality. Validity is broken into 8 bit flags. Each
bit=0 if the status is routine but the bit = 1 if the status is
not routine. Bit 0 is the most significant bit (i.e., if bit i=1
and other bits = 0, the unsigned integer value is 2**(8-i)-1 ).
1 Non routine spacecraft orientation (2 or 3)
2 Non routine ACS mode (other than 4)
3 Non routine yaw update status (0 or 1)
4 Non routine instrument status (other than 1)
5 Non routine QAC (non-zero)
6 Spare (always 0)
7 Spare (always 0)

Bit and Meaning of Geolocation Quality
Bit Meaning if bit=1
0 Grossly bad geolocation results:
* Spacecraft position vector magnitude outside range 6720 to 6740 km.
* Z component of midpoint of scan outside range -4100 to 4100 km.
* Distance from S/C to midpoint of scan outside range 340 to 360 km.
1 Unexpectedly large scan to scan jumps in geolocated positions in along and cross track directions for first, middle, and last pixels in each scan. Allowed duration from nominal jump in along track motion = 0.06 km (first pixel), 0.04 km (middle pixel), and 0.06 km (last pixel). Allowed duration from nominal jump in cross track motion = 0.05 km (first pixel), 0.04 km (middle pixel), and 0.05 km (last pixel). Bit set in normal mode only.
2 Scan to scan jumps in yaw, pitch, and roll exceed maximum values. Values are : yaw = 0.0001 radians; pitch = 0.0001 radians; roll = 0.0001 radians. Bit set in normal control mode only.
3 In normal mode, yaw outside range (-0.003, 0.003) radians; pitch outside range (-0.007, 0.007) radians; roll outside range (-0.007, 0.007).
4 Satellite undergoing maneuvers during which geolocation will be less accurate.
5 Questionable ephemeris quality (including use of predicted Ephemeris for quicklook) or questionable UTCF quality.
6 Geolocation calculations failed (fill values inserted in the per pixel geolocation products, but not in metadata).
7 Missing attitude data. ACS data gap larger than 20 seconds.

Value and Meaning of
Current Spacecraft Orientation TTT
Value Meaning
0 +x forward
1 -x forward
2 -y forward
3 Inertial - CERES Calibration
4 Unknown Orientation

Value and Meaning of
Current ACS Mode
Value Meaning
0 Standby
1 Sun Acquire
2 Earth Acquire
3 Yaw Acquire
4 Nominal
5 Yaw Maneuver
6 Delta-H (Thruster)
7 Delta-V (Thruster)
8 CERES Calibration

Bit and Meaning of
Instrument Status
Bit Meaning
0 Receiver Status (1=ON, 0=OFF)
1 Spin-up Status (1=ON, 0=OFF)
2 Spare Command 1 Status
3 Spare Command 2 Status
4 1 Hz Clock Select (1=A, 0=B)
5 21 GHz Cold Count Flag
6 Spare Command 4 Status
7 Spare Command 5 Status
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Last updated: Sep 09, 2009 02:26 PM ET