Global Monthly Vegetation Cover Data Introduction

Introduction Page, Preface

This CD-ROM contains time series of global monthly mean Normalized Difference Vegetation Index (NDVI) data produced from the Advanced Very High Resolution Radiometer (AVHRR) measurements. This data set is based on the weekly composite maps produced within the Global Vegetation Index (GVI) project in the Satellite Research Laboratory of the Office of Research and Applications, National Environmental Satellite, Data, and Information Service (NESDIS), National Oceanic and Atmospheric Administration (NOAA). The GVI project was sponsored by the NOAA Climate and Global Change Program for the purpose of developing improved operational GVI products that are useful for global climate studies.

The data on this CD-ROM are the GVI C3.2/M15 products (for the nomenclature, see Gutman et al. 1995, which are also known as the Third Generation C-Level NDVI data (see the NOAA Global Vegetation Index User's Guide). The products are given at 0.15 degree resolution in a rectangular latitude/ longitude (equal angle) projection (also known as Plate Carrée projection) and comprise NDVI monthly maps for the period of April 1985 - December 1997. The C-Level NDVI digital data are contained in the "ndvi-12/data/digital" directory on this CD-ROM.

Also included on this CD-ROM are monthly Quality Description (QD) files containing compressed information on the monthly mean satellite sun zenith and viewing angles, which may be useful in identifying geometry biases, and the number of weeks used to calculate monthly statistics for each individual year after cloud screening. In addition, a stationary file (one for all the months) is included consisting of auxiliary masks (AM) that contain land/sea tag, political boundaries and two stationary (independent of the month) masks based on maximum (Vmax) and minimum (Vmin) annual NDVI values characterizing low annual variability in NDVI (Vmax-Vmin<0.2) for evergreen (Vmax>0.45) and deserts (Vmax<0.2). Both the QD and AM data are respectively contained in the "ndvi-12/data/qd" and "ndvi-12/data/am" directories on this CD-ROM.

To facilitate geophysical analysis, gif files of the data and an offline browser (Navroad) are included on this CD-ROM.

The data processing is briefly described in the next section. A description for converting the NDVI values to green vegetation fraction, f_g, is included in the NDVI (8 bit) Data Format Description. Its full description is given in Gutman et al. 1995. Programs to read the data on several platforms and their documentation are also included in the Digital Data Information portion of this CD-ROM.