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Variables

Elevation Grid Header Record

Bytes

FORTRAN
Variable
Type

Description

1-4

I*4

Number of i values in the grid

5-8

I*4

Number of j values in the grid

9-12

I*4

Starting north latitude of grid in degrees North (x 10^6) (this will be approximate for a polar stereographic grid)

13-16

I*4

Starting east longitude of grid in degrees East (x 10^6) (this will be approximate for a polar stereographic grid)

17-20

I*4

Ending north latitude of grid in degrees North (x 10^6) (this will be approximate for a polar stereographic grid)

21-24

I*4

Ending east longitude of grid in degrees East (x 10^6) (this will be approximate for a polar stereographic grid)

25-28

I*4

Status word for data used to generate grid. A zero in any bit position indicates that the correction is not applied.

Bits

Value

Description

0-23

Unused

24

1

Slope correction applied

0

Slope correction not applied

25

Unused

26

1

Solid tides removed

0

Solid tides not removed

27

1

Retracking correction applied

0

Retracking correction not applied

28

1

Center of gravity bias applied

0

Center of gravity bias not applied

29

1

Tropospheric correction applied

0

Tropospheric correction not applied

30

1

Ionospheric correction applied

0

Ionospheric correction not applied

31

1

Time bias applied

0

Time bias not applied

29-32

I*4

Polar stereographic grid size conversion and scaling factor from half-inch grids on projection plane to the desired grid size (x 10^6)

33-36

I*4

The number of grids of desired size from the pole to the equator based on the grid size conversion and scaling factor (x 10^6)

37-40

I*4

Latitude of the map perimeter in degrees North (x 10^6)

41-44

I*4

Greenwich orientation in degrees (x 10^6)

45-48

I*4

Polar stereographic switch
=0: Grid has constant increment in latitude, longitude
=1: Grid is in polar stereographic projection

49-52

I*4

Number of I-axis divisions to the extent of the map perimeter

53-56

I*4

Number of J-axis divisions to the extent of the map perimeter

57-60

I*4

J coordinate of the projected pole

61-64

I*4

I coordinate of the projected pole

65-68

I*4

Minimum J index of the grid

69-72

I*4

Maximum J index of the grid

73-76

I*4

Minimum I index of the grid

77-80

I*4

Maximum I index of the grid

81-180

Padded to keep same size as data records

Elevation Grid Data Records

Bytes

FORTRAN
Variable
Type

Description

1-4

I*4

Condition number of the matrix used in the least squares solution to the function (x 10^6)

5-8

I*4

Capsize in degrees latitude -- radius from grid location defining area from which data was used to define grid (x 10^6)

9-12

I*4

North latitude of grid point in degrees (x 10^6)

13-16

I*4

East longitude of grid point in degrees (x 10^6)

17-20

I*4

Height values of the grid at location relative to sea level in meters (x 10^5)

21-24

I*4

Number of data values that were used to calculate grid value

25-28

I*4

Number of parameters used to define function, NPT, (equals 0, 3, or 6)
0 indicates a nondefined grid value

29-52

I*4

Six gridding function coefficients
If NPT is < 6, then the rest of the coefficients are initialized to zero (x 10^5)

53-76

I*4

Set of null coefficients associated with any negligible singular values
If NPT is < 6, then rest of coefficients are set to zero (x 10^6)

77-80

I*4

Distance in kilometers from grid locations to closest data point (x 10^6)

81-84

I*4

North latitude of closest data point to grid location in degrees (x 10^6)

85-88

I*4

East longitude of closest data point to grid location in degrees (x 10^6)

89-92

I*4

Height associated with closest data point to grid location in meters (x 10^5)

93-96

I*4

Standard deviation of the data with respect to the gridding function in meters (x 10^6)

97-180

I*4

Correlation matrix from solution
This is a symmetrical 6 X 6 matrix, so only the upper triangular portion is stored
The order of storage: Elements 1-6 are the first row elements; 7-11 columns are 2-6 of the second row, etc. (x 10^5)

Georeferenced Database Header Record

Bytes

FORTRAN
Variable
Type

Description

1-4

I*4

Number of latitude rows in the database

5-8

I*4

Northwesternmost latitude of database in degrees North (x 10^5)

9-12

I*4

Northwesternmost longitude of database in degrees East (x 10^5)

13-16

I*4

Southeasternmost latitude of database in degrees North (x 10^5)

17-20

I*4

Southeasternmost latitude of database in degrees East (x 10^5)

21 to NROWS*4-1

I*4

Width of each latitude row in degrees (x 10^5), starting with the southernmost row
This is dimensioned by the number of latitude rows in the database

next NROWS*4

I*4

The number of longitude divisions in each latitude row, starting with the southernmost row
This is dimensioned by the number of latitude rows in the database

next 4 bytes

I*4

Logical record number in database at which directory starts

next 4 bytes

I*4

Unused

next 4 bytes

I*4

Maximum latitude of data (may not be equal to value in bytes 5-8 if data is subarea of the total bin configuration area) in deg N (x 10^6)

next 4 bytes

I*4

Minimum longitude of data (may not be equal to value in bytes 5-8 if data is subarea of the total bin configuration area) in deg E (x 10^6)

next 4 bytes

I*4

Minimum latitude of database (may not be equal to value in bytes 13-16 if data is subarea of the total bin configuration area) in deg E (x 10^6)

next 4 bytes

I*4

Maximum longitude of database (may not be equal to value in bytes 17-20 if data is subarea of the total bin configuration area) in deg E (x 10^6)

next 20 bytes

C*20

Character data description of orbit used in calculation of surface height in database

next 4 bytes

I*4

YYMMDD database beginning time

next 4 bytes

I*4

HHMMSS database beginning time

next 4 bytes

I*4

YYMMDD database ending time

next 4 bytes

I*4

HHMMSS database ending time

next 4 bytes

I*4

Mission word

Bits

Value

Description

0-25

0

Unused

26

1

GEOS-C data included

0

GEOS-C data not included

27

1

ERS-1 data included

0

ERS-1 data included

28

1

TOPEX data included

0

TOPEX data not included

29

1

GEOSAT-ERM data not included

0

GEOSAT-ERM data not included

30

1

GEOSAT-GM data included

0

GEOSAT-GM data not included

31

1

Seasat data included

0

Seasat data not included

next 4 bytes

I*4

Mission status word for Seasat

next 4 bytes

I*4

Mission status word for GEOSAT-GM

next 4 bytes

I*4

Mission status word for GEOSAT-ERM

next 4 bytes

I*4

Mission status word for TOPEX

next 4 bytes

I*4

Mission status word for ERS-1

next 4 bytes

I*4

Mission status word for GEOS-C

Mission status words for altimetry data:

Bits

Value

Description

0-22

0

Unused

23

1

Ocean tides removed

0

Ocean tides not removed

24

1

Slope correction applied

0

Slope correction not applied

25

1

Orbit adjustment 1 applied

0

Orbit adjustment 1 not applied

26

1

Solid tides removed

0

Solid tides not removed

27

1

Retracking correction applied

0

Retracking correction not applied

28

1

Center of gravity bias applied

0

Center of gravity bias not applied

29

1

Tropospheric correction applied

0

Tropospheric correction not applied

30

1

Ionospheric correction applied

0

Ionospheric correction not applied

31

1

Time bias applied

0

Time bias not applied

Georeferenced Database

Subgroup 1: One logical record for each bin containing data

Bytes

FORTRAN
Variable
Type

Description

1-4

I*4

Indicates the number of logical records that follow which are located in the bin

5-32

Unused

Subgroup 2: One logical record for each data point in the bin

Bytes

FORTRAN
Variable
Type

Description

1-4

I*4

North latitude of datum point in degrees (x 10^6)

5-8

I*4

East longitude of datum point in degrees (x 10^6)

9-12

I*4

Surface height relative to the ellipsoid in centimeters

13-16

I*4

Height sigma, arbitrary value of 1.0 meter used (x 10^5)

17-24

Reserved for future use

25-28

I*4

Rev number

29-32

I*4

Slope correction in meters (x 10^5)
<(-999999999 if unavailable)

Subgroups 1 and 2 are repeated for as many bins with data.

Georeferenced database bin directory

Bytes

FORTRAN
Variable
Type

Description

1-4

I*4

Record number at which data for bin 1 starts

5-8

I*4

Record number at which data for bin 2 starts

9-12

I*4

Record number at which data for bin 3 starts

13-16

I*4

Record number at which data for bin 4 starts

17-20

I*4

Record number at which data for bin 5 starts

21-24

I*4

Record number at which data for bin 6 starts

25-28

I*4

Record number at which data for bin 7 starts

29-32

I*4

Record number at which data for bin 8 starts

Note: The directory contains as many 32-byte logical records as necessary to designate the record locations of all bins. Any geographical bin for which there is no data has a 0 put in as the starting record number.