gahr1sdd.

11/30/95 kvj #3

02/13/96 kvj #6 -- continuing to add defs and check against

gahr1sdc

02/19/96 kvj #7 -- ediiting. Also see av1bsif\gahr1s.lst

03/21/96 kvj #9 -- adding definitions from Irv & Emily.

03/25/96 kvj #10 -- deleted scaling factors for Nav terms. Added

Irv's definitions (see {note 5}).

configured 05/22/96 kvj

05/29/96 kvj #11 -- Had to draw down a second time after a

directory got clobbered on 5/28.

DATA_FRAME_COUNT -> FRAMES_W/O_SYNC_ERR. Reformatted.

05/29/96 kvj #12 -- alphabetical order.

05/30/96 kvj #13 -- reformatted.

05/31/96 kvj #14 -- corrected EARTH/SUN_DISTANCE_RATIO.

07/29/96 kvj #15 -- corrections after design reviews.

reviewed 08/05/96 msg -- comments in <<msg-..>>

08/06/96 kvj #16 -- corrections after review by msg.

08/07/96 msg #17 -- Changed zero's to missing values as the

default SECONDARY_INSTRUMENT_STATUS

configured 08/07/96 msg

reviewed 08/07/96 jds -- comments in <<..>>

08/12/96 kvj #18 -- corrections after review by jds.

----------------------------------------------------------------

Data Dictionary: GAC 1b* Header Record

A/D_CONVERTER_TEMP_CONV_COEF Polynomial coefficients for

converting counts to the temperature of the A/D converter. {note

1}

ARGUMENT_OF_PERIGEE Argument of Perigee in degrees {note 3}

ATTITUDE_ERROR_CORRECTION Flag indicating whether the dynamic

attitude corrections have been performed. Currently (1995) the

earth location module (AELDS) does not perform these

corrections; the advisability of making these corrections is

under study. 0 --> no corrections; 1 --> the corrections were

performed.

A_R_EQUIV_FILTER_WIDTH An array containing the filter width of

channels 1, 2, and 3A. The filter (or channel) width can be used

to convert the band radiance to spectral radiance. These are

constants supplied to the PDP through the CPIDS database.

A_R_SOLAR_FILTERED_IRRADIANCE An array containing the solar

filtered irradiance for channels 1, 2, and 3A. The solar

filtered irradiance may be used to convert the band radiance to

reflectance factor. These are constants supplied to the

preprocessor through the CPIDS database.

BASEPLATE_TEMP_CONV_COEF Polynomial coefficients for converting

counts to the baseplate temperature. {note 1}

BB_TEMP_1_CONV_COEF Polynomial coefficients for converting

counts from PRT #1 to temperature. {note 1} These

coefficients only apply to the PRT reading given in the TIP

analog telemetry.

BB_TEMP_2_CONV_COEF Polynomial coefficients for converting counts

from PRT #2 to temperature. {note 1}

BB_TEMP_3_CONV_COEF Polynomial coefficients for converting counts

from PRT #3 to temperature. {note 1}

BB_TEMP_4_CONV_COEF Polynomial coefficients for converting counts

from PRT #4 to temperature. {note 1}

BLACKBODY_CH3B_CONV_COEF Polynomial coefficients for converting

PRT counts to the temperature. {note 1} << These and those for

channels 4 & 5 may be unnecessary. That telemetry point isn't

really measuring a temperature, it's sampling the output of a

sample-and-hold circuit which samples the IR Channel 3 analog

data signal once each scan line as the instrument views the

blackbody calibration target. However, since only 8 bits are

given, some conversion might be required if, for example, one

wished to apply the calibration.>>

BLACKBODY_CH4_CONV_COEF Polynomial coefficients for converting

counts to the temperature. {note 1}

BLACKBODY_CH5_CONV_COEF Polynomial coefficients for converting

counts to the temperature. {note 1}

CLOCK_UPDATE_RECORD The first record in this data set showing

the result of an update to the spacecraft's clock. A value of

zero indicates that no update occurred during the course of

this orbit.

COMPLETE_SCAN_COUNT The total number of calibrated and earth

located scans in this data set.

COMPONENT_ID Identifies the type of the file, in the case of a

GAC 1b* data set it should contain the following character

string: GAC_1BS. {note 2}

COOLER_HOUSING_TEMP_CONV_COEF Polynomial coefficients for

converting counts to the patch cooler housing temperature. {note

1}

CPIDS_FILE_ID Integer code identifying the CPIDS database used

by the preprocessor to create this data set. <<TBD. This is

similar but not identical to the obsolete CALIBRATION PARAMETER

ID given in pre-K 1b data sets.>>

CREATION_YEAR_DAY The 4-digit year and the day of year, in that

order, that this 1b* data set was created.

<<data_frame_count?>>

DATA_GAPS_COUNT The number of separate data gaps of one or more

scans.

DATA_MODE From the PACS Status. 0 --> test data; 1 --> flight

data.

DATA_SOURCE The CDA station that received the satellite

transmission of this data. 1 --> Gilmore; 2 --> Wallops; 3 -->

SOCC <<?>>.

DATA_TYPE_CODE Indicates the data type of the data set. In

this case the value will be 2 --> GAC. ( 1--> LAC, 3 --> HRPT)

DETECT4_BIAS_VOLT_CONV_COEF Polynomial coefficients for

converting counts to the bias voltage of detector #4. {note 1}

DETECT5_BIAS_VOLT_CONV_COEF Polynomial coefficients for

converting counts to the bias voltage of detector #5. {note 1}

EARTH/SUN_DISTANCE_RATIO distance from Earth to the sun in

Astronomical units (mean distance is 1AU)

EARTH_LOC_ERROR_CODE If EARTH_LOC_ERROR_RECORD is nonzero, this

field contains the value from EARTH_LOCATION_PROBLEM_INDICATOR

as reported on the scan for which the error was reported.

EARTH_LOC_ERROR_RECORD If an earth location error is detected

during the period covered by this data set, the record number of

the first occurrence is given in this field. If no errors are

detected this field contains 0.

EARTH_LOC_TEST_ACTIVE Flag set to 1 if the reasonableness test

of the earth locations are active; otherwise, set to 0.

EARTH_SHIELD_POS_CONV_COEF Polynomial coefficients for

converting counts to an indication of the earth shield position.

{note 1}

ECCENTRICITY Eccentricity {note 3}

ELECT_TEMP_CONV_COEF Polynomial coefficients for converting

counts to the electronics temperature. {note 1}

ELEC_CUR_CONV_COEF Polynomial coefficients for converting counts

to the electronics current. {note 1}

END_DAY_OF_YEAR Day-of-year on which the last scan in this data

set occurred.

END_JULIAN_DAY Day count, from 00h, 1 Jan. 1950, of the last

scan in this data set. << Is 1 Jan 1950 day 0 or day 1?>>

<<This is a different definition for Julian day. We (the PDP)

have defined, and are using, Julian day as the number of days

since Jan. 1, 4713 BC.>>

END_MILLISECONDS_OF_DAY Time of day in milliseconds at which

the last scan of this data set began. <<Scan times on data

records will not mark the scan start, but rather the center of

dwell of the first FOV.>> <<There is no dwell for a GAC

observation.>>

END_YEAR 4-digit year in which the last scan in this data set

occurred.

FIRST_SCAN_RECORD The record number in this data set of the

first scan.

FRAMES_W/O_SYNC_ERR The number of scans reported by this data

set having the sync error bit on (set by PACS processing),

indicating that the frame sync word error was greater than

zero. <<TBC. Related to the "count of data frames without

frame sync word error" field (byte 131) in the 1b, which in turn

is probably related to the Quality Indicator Bit Field (bytes

23-26), and in particular: "frame sync word greater than 0" (bit

25). Also, in the 1b*, see FRAME_SYNC_ERROR. This flag should

be set during PACS processing; see the POD, Table 3.1.2.1-2 on

3-5.>>

<<This field is not shown in the structure file.>>

HEX_AFFFFFFF The hex code AFFFFFF stroed in the natural order of

the target computer.

INCLINATION Inclination in degrees {note 3}

INSTRUMENT_ID Code identifying the AVHRR instrument that

produced the data for this data set. This information comes

from the spacecraft's CPIDS database, coefficient

AVHRRPRI/GENERAL/INSTRUID.

INSTRUMENT_STATUS The status of the instrument at the

beginning of the period covered by this data set. Status is

determined by a subset of the AVHRR digital b telemetry {UIIS

Table 10} which comes from the embedded TIP data. The

components are as follows:

+

motor/telemetry (0 -> off, 1 -> on)

electronics/telemetry (0 -> off, 1 -> on)

channel 1 status (0 -> disable, 1 -> enable)

channel 2 status (0 -> disable, 1 -> enable)

channel 3A status (0 -> disable, 1 -> enable)

channel 3B status (0 -> disable, 1 -> enable)

channel 4 status (0 -> disable, 1 -> enable)

channel 5 status (0 -> disable, 1 -> enable)

+

Because of the rates at which the digital b points are sampled by

the TIP processor on board the spacecraft, the inital status

cannot be completely determined until several scan lines have

been processed.

LAST_SCAN_RECORD The record number in this data set of the last

scan.

LETTER_Q The letter Q encoded for the target computer. A 1b*

for the CEMSCS would have the letter Q encoded in EBCDIC;

for the PC it would be encoded in ASCII.

LOCAL_DATA_SET_NAME The name of this 1b* data set on the target

computer.

MEAN_ANOMALY Mean Anomaly in degrees {note 3}

MISSING_SCAN_COUNT The difference between the total number of

scans expected during the period of this data set and

SCAN_COUNT.

MORNING_AFTERNOON_INDICATOR Indicates whether the spacecraft

crosses the equater going north in the morning or in the

afternoon.

MOTOR_CURRENT_CONV_COEF Polynomial coefficients for converting

counts to the current. {note 1}

MOTOR_HOUSING_TEMP_CONV_COEF Polynomial coefficients for

converting counts to the temperature of the motor housing. {note

1}

NADIR_TOLERANCE a value in kilometers that is used to determine

when earth location data at the satellite subpoint are outside

an acceptable range. The "bad earth location" flag tolerance is

exceeded. Generally, the range is set between 0.1 and 25.2

kilometers. Zero indicates no checking is done.

NUMBER_OF_HEADER_RECS The total number of header records in the

1b* data set. NUMBER_OF_HEADER_RES + 1 gives the record number

of the first data record.

ORBIT_VECTOR_DAY_OF_YEAR Day count from the beginning of the

year for the reported orbital elements.

ORBIT_VECTOR_EPOCH_YEAR Four-digit year of the date for the

reported orbital elements.

ORBIT_VECTOR_UTC_TIME_OF_DAY Actual time for which the reported

orbit vector is valid in milliseconds.

ORIGINAL_DATA_SET_NAME The data set name used on the computer

that created this 1b*.

PATCH_POWER_CONV_COEF Polynomial coefficients for converting

counts to the patch power. {note 1}

PATCH_TEMP_CONV_COEF Polynomial coefficients for converting

counts to the patch temperature. {note 1}

PATCH_TEMP_EXT_CONV_COEF Polynomial coefficients for converting

counts to the extended patch temperature. {note 1}

PI The number 3.141459 stored in the floating point format of

the target processor.

PITCH_ERROR_CONSTANT Pitch Euler angle reported in degrees

times 1000 based on instrument misalignment errors or observed

image errors. Positive pitch is down.

POSITION_VECTOR_X_COMPONENT Position Vector X Component in

kilometers {note 4}

POSITION_VECTOR_Y_COMPONENT Position Vector Y Component in

kilometers {note 4}

POSITION_VECTOR_Z_COMPONENT Position Vector Z Component in

kilometers {note 4}

PRIMARY_CAL_ALGORITHM_ID Identifies the primary calibration

algorithm.

PRIMARY_CAL_ALGORITHM_OPTION <<redefined 11/30/95>> Gives the

settings of the data switches that control the primary

calibrations of the IR channels. The item is a 2x3 array of

1-byte indicators. The 3 columns correspond to the three IR

channels and follow the natural order. The first row in each

column corresponds to resolution ( 0 --> high and 1 --> low) and

the second tells whether substitution coefficients will be

supplied by the PDP in cases in which the gain anomaly is

detected (0 --> no, 1 --> yes).

PROCESSING_BLOCK_ID The processing block ID. Seven digits

identifying the starting and ending orbits. The first 5 digits

give the starting orbit; the last two digits are the the last

two digits of the ending orbit. <<See POD, 7/91; pg. 2-4 for

exceptions.>>

PROCESSOR_ID The ID of the computer program that originally

created this 1b*.

PRT_CONV_COEF A table giving the conversion coefficients that

will convert PRT counts reported in the GAC frames to

temperatures. <<new>>

PSEUDO_NOISE_FLAG Pseudo noise indicator from the PACS Status

Bit Field. 0 --> normal data; 1 --> P/N data.

RADIATOR_TEMP_CONV_COEF Polynomial coefficients for converting

counts to the radiator temperature. {note 1}

RAMP_AUTO_CAL_INDICATOR_CH1 Channel 1 ramp calibrations are

reported in the AVHRR telemetry.

RAMP_AUTO_CAL_INDICATOR_CH2 Channel 2 ramp calibrations are

reported in the AVHRR telemetry.

RAMP_AUTO_CAL_INDICATOR_CH3A Channel 3A ramp calibrations are

reported in the AVHRR telemetry.

RAMP_AUTO_CAL_INDICATOR_CH3B Channel 3B ramp calibrations are

reported in the AVHRR telemetry.

RAMP_AUTO_CAL_INDICATOR_CH4 Channel 4 ramp calibrations are

reported in the AVHRR telemetry.

RAMP_AUTO_CAL_INDICATOR_CH5 Channel 5 ramp calibrations are

reported in the AVHRR telemetry. << What does it mean and how

do they get set?>>

REFERENCE_VOLT_CONV_COEF Polynomial coefficients for converting

counts to the reference voltage. {note 1}

RIGHT_ASCENSION Right Ascension of the Ascending Node in

degrees {note 3}

ROLL_ERROR_CONSTANT Roll Euler angle reported in degrees times

1000 based on instrument misalignment errors or observed image

errors. Positive roll is to right.

SCAN_COUNT The total number of scans represented in this data

set.

SECONDARY_CAL_ALGORITHM_ID Identifies the secondary calibration

algorithm.

SECONDARY_CAL_ALGORITHM_OPTION <<redefined 11/30/95>> Gives the

settings of the data switches that control the secondary

calibrations of the IR channels. The item is a 2x3 array of

1-byte indicators. The 3 columns correspond to the 3 IR channels

and follow the natural order. The first row in each column

corresponds to resolution ( 0 --> high and 1 --> low) and the

second tells whether substitution coefficients will be supplied

by the PDP in cases in which the gain anomaly is detected (0 -->

no, 1 --> yes).

SECOND_INSTRUMENT_STATUS An array of indicators giving the

status of the instrument after the first change. If no change

occurs, the indicators are all missing values.

SEMIMAJOR_AXIS Semi-major Axis in kilometers {note 3}

SOLAR_CHANNEL_CAL_DAY_OF_YEAR

SOLAR_CHANNEL_CAL_YEAR

SPACECRAFT_ID NOAA's numerical ID of the spacecraft.

START_DAY_OF_YEAR Day-of-year on which the first scan in this

data set occurred.

START_JULIAN_DAY Day count, from 00h, 1 Jan. 1950, of the first

scan in this data set.

START_MILLISECONDS_OF_DAY Time of day in milliseconds at which

the first scan of this data set began. <<Notice that scan times

on data records will not mark the scan start, but rather the

center of dwell of the first FOV.>>

START_YEAR 4-digit year in which the first scan in this data

set occurred.

STATUS_CHANGE_RECORD If the INSTRUMENT_STATUS changes during

the period covered by this data set, the record number at which

the change is first recognized is given in this field. If no

change occurs this field will contain 0.

SYNC_ERROR_COUNT The sum of all (PACS-detected) auxiliary sync

errors detected in the input data for the entire data set; i.e.,

the PDP extracts the number of frame sync bit errors from the

frame quality flags in the 1a (see 1a requirements Table 2.3-4)

and accumulates the sum over the period covered by the data set.

TAPE_DIRECTION 0 --> time decrementing. << Who cares? The

1b*/1b will always be in increasing order.>>

TIME_SEQUENCE_ERROR_CODE If TIME_SEQUENCE_ERROR_RECORD is

nonzero, this indicator array contains the values reported in

TIME_PROBLEM_INDICATOR on the data record having the problem.

TIME_SEQUENCE_ERROR_RECORD If the pattern of scan times changes

during the period covered by this data set, the first record

showing the new pattern is given in this field. If the pattern

remains consistent throughout, this field is 0. This is

detemined by the PDP, and the first record that shows either

condition 3 or 4<<4 is now spare>> in the TIME_PROBLEM_INDICATOR will have its

number placed in this field.<<Should this definition be expanded

to include all time errors (i.e., check conditions 1 and 2 as

well), and not just when there is a change in the scan time

pattern (i.e., a time discontinuity)?>>

TIP_PARITY_ERROR_COUNT The count of the total number of

PACS-detected TIP parity errors. The PDP finds the number of

TIP parity errors that were detected (by PACS) on each scan and

accumlates the sum over all the scans covered by the data set.

TIP_SOURCE_CODE Meaningless for this data set. The value will

be set to 0.

TRANSLATOR_ID The ID of the computer program that translated

this 1b* from some other format (e.g., 1b) or ported it from

some other computer (e.g., CEMSCS to Cray).

T_R_CENTRAL_WAVE_NUMBER An array containing the central wave

numbers of the 3 IR channels. <<temperature dependent?>>

T_R_CONVERSION_CONSTANT_1

T_R_CONVERSION_CONSTANT_2

VELOCITY_VECTOR_X_DOT_COMPONENT Velocity Vector X-dot Component

in kilometers/second {note 4}

VELOCITY_VECTOR_Y_DOT_COMPONENT Velocity Vector Y-dot Component

in kilometers/second {note 4}

VELOCITY_VECTOR_Z_DOT_COMPONENT Velocity Vector Z-dot Component

in kilometers/second {note 4}

VERSION_NUMBER Integer giving the version number of the

structure file used to create this 1b* data set.

YAW_ERROR_CONSTANT Yaw Euler angle reported in degrees times

1000 based on instrument misalignment errors or observed image

errors. Positive yaw is clockwise as viewed from above.

-----------------------------------------------------------------

{note 1} These coefficients are used to convert counts found in

the TIP analog telemetry to engineering units. See the UIIS for

AVHRR Table 11.

If A is an array holding the polynomial coefficients dimensioned

as A(0:4), and X hold the counts reported by the spacecraft, then

the desired quantity Q is

Q = A(0) + X*A(1) + X^2*A(2) + ... + X^4*A(4).

{note 2} The header record of the 1b* is actually written twice.

The first time it is written is at the beginning of processing,

before all the values needed are known. The 1b* is written

sequentially and then at the end of processing, it is closed and

reopened for direct aceess so that the header can be rewritten

with the final values of quality indicators, etc. Should any

thing happen to interrupt processing, it is possible that an

incomplete 1b* data set might result. Normally this would be

prevented through the use of JCL. But as an additional

precaution, the component ID will be set to all blanks when the

header record is first written, and then set to the correct value when

it is written the final time.

<<Will the component ID field be blanks when initialized or

missing value (SPVAL:CH1SPV)?>>

{note 3} These parameters are the satellite Osculating

(instantaneous) Keplerian orbital elements valid for the epoch

time provided (Inertial Reference Frame).

{note 4} These six parameters are the satellite Osculating

(instantaneous) Cartesian orbital elements valid for the epoch

time provided (Inertial Reference Frame).

{note 5} General navigation terms:<<there are no references to

this note>>

Euler angles: a set of three angles which define the orientation

of a body with respect to a reference frame using a series of

pure rotations, resulting in an orthogonal transformation. As

an example, the system is rotated about the x axis by an angle

a, then about the rotated y axis by an angle b, and finally

about the doubly rotated z axis by an angle c. The order of the

rotations may vary.

Inertial Reference Frame: a coordinate system with the origin at

the center of the Earth, the positive x-axis directed toward the

vernal equinox, the z-axis is normal to the equatorial plane in

the direction of the earth rotational angular momentum vector,

and y-axis is normal to the x and z axis to form a right-handed

system.