GINI Format for AWIPS Satellite Data

1. GINI Overview

The GINI product is broken down into two subsections:

1. Product Definition Block

The product definition block is a 512 byte block which describes the image data.
 
Octet/Byte Description
01 Source - 1=NESDIS
02 Creating entity
03 Sector identifier
04 Physical element
05-06 Number of logical records (scan lines)
07-08 Size of logical record (pixels per scan line)
09 Valid Time - Year of century
10 Month
11 Day
12 Hour
13 Minute
14 Seconds 
15 Hundredths of seconds
16 Map projection indicator
17-41 Projection Definition (see below)
42 Image resolution
43 Data compression indicator (1=compressed, 0=no compression)
44 Version of PDB
45-46 Size of PDB in bytes
47 Navigation/Calibration indicator (0=nav/cal not included, 1=nav/cal included, 2=nav only, 3=cal only)
48-512 Reserved

3. Projection Definition

This section describes the parameters needed to define the projection of the image.

3.1 Projection Definition for Polar Stereographic and Lambert Conformal Images


Octet CONTENT & MEANING
17-18 Nx - Number of points along x-axis
19-20 Ny - Number of points along y-axis
21-23 La1 - Latitude of first grid point
24-26 Lo1 - Longitude of first grid point
27 Reserved - currently 0
28-30 Lov - The orientation of the grid; i.e., the east longitude value of the meridian which is parallel to the y-axis (or columns of the grid) along which latitude increases as the y-coordinate increases. (Note: The orientation longitude may, or may not, appear within a particular grid.)
31-33 Dx - the X-direction increment (see note 2)
34-36 Dy - the Y-direction increment (see note 2)
37 Projection center flag (see note 5)
38 Scanning mode
39-41 Latin - The latitude at which the Lambert Conformal projection is tangent to the earth.  Set to 0 for stereographic projections.

Notes:

  1. Latitude and longitude are in 10-4 (ten-thousandths)
  2. Increments are in units of tenths of meters, at the tangent latitude (60 degree for stereographic) circle nearest to the pole in the projection plane.
  3. Latitude values are limited to the range 0 - 900,000. Bit 1 is set to 1 to indicate south latitude.
  4. Longitude values are limited to the range 0 - 3,600,000. Bit one is set to 1 to indicate west longitude.
  5. Projection Center Flag -

    6. Bit 1 set to 0 if the North pole is on the projection plane.
    Bit 1 set to 1 if the South pole is on the projection plane.

3.4 Grid Definition for Mercator Grids


Octet CONTENT & MEANING
17-18 Nx - Number of points along a latitude circle
19-20 Ny - Number of points along a longitude meridian
21-23 La1 - Latitude of first grid point
24-26 Lo1 - Longitude of first grid point
27 Resolution flag
Bit 1 = 0 - Direction increments not given, 1 - Direction increments given
28-30 La2 - latitude of last grid point
31-33 Lo2 - longitude of last grid point
34-35 Di - the longitudinal direction increment (see note 2)
36-37 Dj - the latitudinal direction increment (see note 2)
38 Scanning mode
39-41 Latin - The latitude(s) at which the Mercator projection cylinder intersects the earth. 

Notes:

  1. Latitude and longitude are in 10-4 (ten-thousandths)
  2. Set to 0
  3. Latitude values are limited to the range 0 - 900,000. Bit 1 is set to 1 to indicate south latitude.
  4. Longitude values are limited to the range 0 - 3,600,000. Bit one is set to 1 to indicate west longitude.
  5. The latitude and longitude of the last grid point should always be given.

2. Image Data Section

This section contains the binary image data.  All image values/pixels are 8 bit values organized by scanline.  The scan mode determines the order in which each value is placed in the IDS.

A. Creating Entity

Value Contents
07 DMSP
08 GMS
09 Meteosat
10 GOES-7
11 GOES-8
12 GOES-9
13 GOES-10
14 GOES-11
15 GOES-12

B. Sector Identifier

Value  
0 Northern hemisphere composite
1 Eastern CONUS
2 Western CONUS
3 Alaska regional
4 Alaska national
5 Hawaii regional
6 Hawaii national
7 Puerto Rico regional
8 Puerto Rico national
9 Supernational composite

C. Physical Element

Value  
1 Visible
2 3.9 micron IR
3 6.7 micron IR (water vapor)
4 11 micron IR (traditional IR)
5 12 micron IR
6 Derived #1
7 Derived #2
8 Derived #3
9 Derived #4

D. Scanning Mode Flag

BIT VALUE MEANING
1 0 Points scan in +i direction
  1 Points scan in -i direction
2 0 Points scan in -j direction
  1 Points scan in +j direction
3 0 Adjacent points in i direction are consecutive (FORTRAN: (I,J))
  1 Adjacent points in j direction are consecutive (FORTRAN: (J,I))
Note: i direction is defined as west to east along a parallel of latitude, or left to right along an x axis. j direction is defined as south to north along a meridian of longitude, or bottom to top along a y axis.