ISLSCP Initiative II

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Vegetation Data

NOAA 5-year Average Monthly Snow-free Albedo from AVHRR

The objective of this work was to produce a monthly climatology of broadband surface albedos for use in global numerical weather prediction models at the National Centers for Environmental Prediction (NCEP). The dataset is compatible in temporal coverage and spatial resolution with a monthly climatology of green vegetation fraction (Gutman and Ignatov, 1998) delivered earlier and currently in use at NCEP. 5-year monthly means of clear-sky, surface, broadband, snow-free albedos for overhead sun illumination angle. Files showing the differences between the original data set and the Land/water mask used in the International Satellite land Surface Climatology Project (ISLSCP) Initiative II are also provided.

Data Provider: Ivan A. Csiszar

Data Files (ISLSCP II Disc #1)

Data Set Documentation

Image Viewing Tutorial

File Information

All of the files in the ISLSCP Initiative II data collection are in the ASCII, or text format. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. The files at different spatial resolutions each contain the following numbers of column and rows:
      One degree: 360 columns by 180 rows
      1/2 degree: 720 columns by 360 rows
      1/4 degree: 1440 columns by 720 rows
All values are written as floating point values, expressed as a percent albedo, and the `change maps' are given as integer values ranging from -1 to 5. Missing values over water are assigned the value of -99. Missing values over land (such as Greenland and Antarctica) are assigned the value of -88. The data files are PKZip compressed.

The data files fall into the following categories:

1. noaa_albedo_5year_XX_mZZ.asc: 12 Gridded monthly albedo map files, where XX can be either "1d", "hd", or "qd" for spatial resolutions of 1 degree, 1/2 degree, or 1/4 degree, respectively in both latitude and longitude. ZZ is the month from 01 to 12. Note that this albedo data set represents the monthly average using data from a five year period from April 1985 - December 1987 and January 1989 - March 1991.

2. noaa_albedo_5year_XX_mZZ.dif: ASCII tables of "differences", points in the original file that didn't match the ISLSCP-2 Land/Water mask, and were removed from or added to the ASCII map files.

3. noaa_albedo_5year_XX_chngmp.asc: Gridded ASCII map showing the differences between the ISLSCP2 land/water mask and the original data set.

Related Pages:
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Revision Date: July 3, 2005