http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO2/ETOPO2v2-2006/ETOPO2v2g/ETOPO2v2g_ReadMe.txt

 

nETOPO2v2 2006 (version: ETOPO2v2g - Grid-centered registration) Data set credit: U.S. Department of Commerce National Oceanic and Atmospheric Administration National Environmental Satellite, Data, and Information Service National Geophysical Data Center http://www.ngdc.noaa.gov/mgg/fliers/06mgg01.html NOTE: the ETOPO2v2 grid-centered registration grids have recently been re-worked in order to repair some problems. ETOPO2 grids are in meters. Complete ETOPO2v2g grids are under folder http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO2/ETOPO2v2-2006/ETOPO2v2g/ as follows: netCDF/ ETOPO2v2g_f4_netCDF.zip - 4-byte floating pt grid in COARDS-compliant netCDF Format GRD98/ ETOPO2v2g_i2_LSB_GRD98.zip - 2-byte integer Most Significant Byte First (bigendian) grid in GRD98 Format ETOPO2v2g_i2_MSB_GRD98.zip - 2-byte integer Least Significant Byte First (littleendian) grid in GRD98 Format raw-binary/ ETOPO2v2g_i2_LSB.zip - 2-byte integer grid with Least Significant Byte First (littleendian) ETOPO2v2g_i2_MSB.zip - 2-byte integer grid with Most Significant Byte First (bigendian) ETOPO2v2g_f4_LSB.zip - 4-byte floating pt grid with Least Significant Byte First (littleendian) ETOPO2v2g_f4_MSB.zip - 4-byte floating pt grid with Most Significant Byte First (bigendian) NOTE: For Grid-centered grids only, you can create custom grids with user-defined bounds and in several different formats at: http://www.ngdc.noaa.gov/mgg/gdas/gd_designagrid.html ETOPO2v2g Data structure and provenance: First and foremost, ETOPO2v2g eliminates a 1-cell westward bias that was present in ETOPO2 as a result of alignment adjustments to match the choice of grid registration used in sampling GLOBE data. The "g" in the name denotes the grid-centered version. ETOPO2v2g is in a grid-centered registration (pixel registered); the cell boundaries are lines of odd minutes of latitude and longitude, and they are centered on intersections of lines of even minutes of latitude and longitude. This is the same as the original ETOPO2, which was also grid-registered, meaning that cells were centered on the integer multiples of 2 minutes (even minutes) of latitude and longitude and the cell boundaries were consequently defined by lines of odd minutes of latitude and longitude. The first row of 10,801 (360 x 30) cells in ETOPO2 redundantly repeated the same data value, centered on the north pole. A data row, centered on the South Pole, was not included in the original ETOPO2, but exists in ETOPO2v2g. Coverage of ETOPO2v2g is -90deg to +90deg in Latitude, and -180deg to +180deg in Longitude, whereas ETOPO2 covered +90deg to -89deg58' in Latitude and -180Wdeg to +189deg58' in Longitude. The new ETOPO2v2g, with grid centered-registration, contains North and South Pole redundancies but has a different number of cells: 5,401 rows of data (180x30 + 1), each with 10,801 columns of data(360x30 + 1). The extra column of data replicates the first column and is included for GMT compatibility. Other Forms: ETOPO2v2c is in a cell-centered registration (pixel registered); the cell boundaries are lines of even minutes of latitude and longitude, and they are centered on intersections of lines of odd minutes of latitude and longitude. The ETOPO2v2c Cell-centered (pixel-registered) version of ETOPO2 is the definitive version. This ETOPO2v2g was re-interpolated using GMT. For info the building of ETOPO2v2c, see: http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO2/ETOPO2v2-2006/ETOPO2v2c/ETOPO2v2c_ReadMe.txt Availability: ETOPO2v2 is available in its entirety on DVD: http://www.ngdc.noaa.gov/mgg/fliers/06mgg01.html You can create custom gridline-registered grids of ETOPO2 and other grids with lat/lon bounds of your choosing into several formats using: http://www.ngdc.noaa.gov/mgg/gdas/gd_designagrid.html

 

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