Ilya at 12:17, 19 April 2013

Ilya — Fri, 19 Apr 2013 12:17:01 GMT

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	The file format consists of a 300-byte descriptive header followed by a two-dimensional array of one-byte values containing the data. The file header is composed of:		The file format consists of a 300-byte descriptive header followed by a two-dimensional array of one-byte values containing the data. The file header is composed of:
-	• a 21-element array of 6-byte character strings that contain information such as polar stereographic grid characteristics	+	* a 21-element array of 6-byte character strings that contain information such as polar stereographic grid characteristics
-	• a 24-byte character string containing the file name	+	* a 24-byte character string containing the file name
-	• a 80-character string containing an optional image title	+	* a 80-character string containing an optional image title
-	• a 70-byte character string containing ancillary information such as data origin, data set creation date, etc.	+	* a 70-byte character string containing ancillary information such as data origin, data set creation date, etc.

	For compatibility with ANSI C, IDL, and other languages, character strings are terminated with a NULL byte.		For compatibility with ANSI C, IDL, and other languages, character strings are terminated with a NULL byte.

Ilya: Created page with "Format Data are scaled, unsigned flat binary with one byte per pixel, and therefore have no byte order, or endianness. Data are stored as one-byte integers representing scaled…"

Ilya — Fri, 19 Apr 2013 12:15:58 GMT

Created page with "Format Data are scaled, unsigned flat binary with one byte per pixel, and therefore have no byte order, or endianness. Data are stored as one-byte integers representing scaled…"

New page

Format

Data are scaled, unsigned flat binary with one byte per pixel, and therefore have no byte order, or endianness. Data are stored as one-byte integers representing scaled sea ice concentration values. Range section for more information. For each data file, a corresponding browse image file in PNG format is also provided.

The file format consists of a 300-byte descriptive header followed by a two-dimensional array of one-byte values containing the data. The file header is composed of:
• a 21-element array of 6-byte character strings that contain information such as polar stereographic grid characteristics
• a 24-byte character string containing the file name
• a 80-character string containing an optional image title
• a 70-byte character string containing ancillary information such as data origin, data set creation date, etc.

For compatibility with ANSI C, IDL, and other languages, character strings are terminated with a NULL byte.

The file header can be accessed in a variety of ways. For example, it can be treated as a simple sequence of bytes containing ASCII character strings or as a complex data structure of arrays. Table 1 describes the file header.

{| border="0"
|+ Table 1. File Header Description
! scope="col" | Bytes
! scope="col" | Description
|-
|1-6 || Missing data integer value
|-
|7-12 || Number of columns in polar stereographic grid
|-
|13-18 || Number of rows in polar stereographic grid
|-
|19-24 || Unused/internal
|-
|25-30 || Latitude enclosed by polar stereographic grid
|-
|31-36 || Greenwich orientation of polar stereographic grid
|-
|37-42 || Unused/internal
|-
|43-48 || J-coordinate of the grid intersection at the pole
|-
|49-54 || I-coordinate of the grid intersection at the pole
|-
|55-60 || Five-character instrument descriptor (SMMR, SSM/I)
|-
|61-66 || Two descriptors of two characters each that describe the data; (for example, 07 cn = Nimbus-7 ice concentration)
|-
|67-72 || Starting Julian day of grid data
|-
|73-78 || Starting hour of grid data (if available)
|-
|79-84 || Starting minute of grid data (if available)
|-
|85-90 || Ending Julian day of grid data
|-
|91-96 || Ending hour of grid data (if available)
|-
|97-102 || Ending minute of grid data (if available)
|-
|103-108 || Year of grid data
|-
|109-114 || Julian day of grid data
|-
|115-120 || Three-digit channel descriptor (000 for ice concentrations)
|-
|121-126 || Integer scaling factor
|-
|127-150 || 24-character file name (without file-name extension)
|-
|151-230 || 80-character image title
|-
|231-300 || 70-character data information (creation date, data source, etc.)
|}

The data can be read with image processing software by specifying a 300-byte header, with an image size of 304 columns x 448 rows for Arctic data and 316 columns x 332 rows for Antarctic data. In a high-level programming language or image processing software, declare a 300-byte array for the header and an array (for example, 304 x 448 for Arctic) for the image. Read the 300-byte array first, then read the image array.

Products:NSIDC SSMI NRT SEAICE - Revision history

Ilya at 12:17, 19 April 2013

Ilya: Created page with "Format Data are scaled, unsigned flat binary with one byte per pixel, and therefore have no byte order, or endianness. Data are stored as one-byte integers representing scaled…"