Time Dependent Topography Through the Glacial Cycle: Readme File
---------------------------------------------------------------
               World Data Center A- Paleoclimatology
---------------------------------------------------------------
NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!!

CONTRIBUTOR: Prof W.R. Peltier, Dept of Physics, University of Toronto 
IGBP PAGES/WDCA Data Contribution Series #:  93-015
ORIGINAL REFERENCE:
Peltier, W. R., Ice Age Paleotopography, 1994, Science, v. 265, pp. 195-201.

SUGGESTED DATA CITATION:
Peltier, W., 1993, Time Dependent Topography Through Glacial Cycle.  IGBP PAGES/World Data
Center-A for Paleoclimatology Data Contribution Series # 93-015.  NOAA/NGDC
Paleoclimatology Program, Boulder CO, USA.

NAME OF DATA SET: Time Dependent Topography Through the Glacial Cycle
LAST UPDATE:  May 1993 (Receipt by WDC-A)
GEOGRAPHIC REGION: Global
PERIOD OF RECORD: 0-21,000 YBP

LIST OF FILES: Readme (this file), tar files TOP.tar and ICE.tar,  
asciispecial format files located in directory /asciispecial:
ice0.asc through ice21.asc, (Ice extent data files), and 
Top0.asc through Top21.asc (Topography data files).


DESCRIPTION:
ICE-4G model, topography and ice cover data files.

Data 1:	topographical heights at 1 Kyr intervals since the last glacial
	maximum.  Files Top0.asc to Top21.asc

Units:	metres. However in order to present a dataset in positive
	integer format, 10000 has been added.
	i.e if the data in this dataset is called itopog
	    then
		true_topog = itopog - 10000
	true_topog has values within the range [-9300,7200] metres.
Topographical heights are relative to paleo sea level.  

Data 2:	Ice-cover data at 1 Kyr intervals since the last glacial maximum.

Values: 1 if there is ice, 0 otherwise.

Resolution:  1 degree latitude/longitude grid. Data starting at 
(-179.5,+89.5), 180 rows of 360 points along a line of constant 
latitude.

Note:	In some areas, the ice-cover data indicates that there is ice
	while the topographic height is negative indicating that the
	region is below sealevel. In these cases, it should be assumed
	that the area is ice-covered. Either the region is not inundated
	or the ice is floating.

File Formats:
The data files are at 1,000 year intervals, for example 
Top18.asc is the 18,000YBP Topography data file. 

The tar files were created on an SGI machine, you may need to
use dd to swap bytes on other machines (eg Suns):
	  dd if=TOP.tar conv=swab | tar xvof -

Logical Data Structure: 16 bit binary unsigned integers,
			least significant byte first.

There is also an ascii version of top.21 called TOP.21.ascii,
which can be used to check interpretation of the binary files.


ASCII file format is asciispecial, text files suitable for import to 
plotting programs such as Spyglass.   The format includes text 
headers, a listing of lat-long grid values, and the data points 
(specify 1 header line when loading files into Spyglass).