Global AVHRR products for land climate studies

Abstract

Climate studies require long-term sets of geographically referenced global land surface data to initialize and validate numerical models for analysis of complex interactions and feedbacks within the earth system. Conventional ground observations cannot provide all the required information and must be supplemented from satellites. Another application of long term global time series of satellite data is establishing the climatologies of both the top-of-the-atmosphere (TOA) radiances and derived surface characteristics which could in turn be used as a baseline for monitoring the climate scale variability. The AVHRR on board NOAA polar orbiters is the main source of operational global information over land, and this paper gives an overview of the basic concepts in its processing. The necessary steps are explained, and a generic scheme and a nomenclature for data products is proposed. In designing that structure, we have been inspired by the data flow in ISCCP. We describe the present status of the data products available from the NOAA Global Vegetation Index (GVI) dataset, its remaining uncertainties, and potential enhancements using e.g. Pathfinder AVHRR over land (PAL) dataset.