MIDHOLOCENE LAND-SURFACE CONDITIONS IN NORTHERN AFRICA AND THE ARABIAN PENINSULA - A DATA SET FOR THE ANALYSIS OF BIOGEOPHYSICAL FEEDBACKS IN THE CLIMATE SYSTEM

Large changes in the extent of northern sub tropical arid regions duri ng the Holocene are attributed to orbitally forced variations in monso on strength and have been implicated in the regulation of atmospheric trace gas concentrations on millenial timescales. Models that omit bio geophysical feedback, however, are unable to account for the full magn itude of African monsoon amplification and extension during the early to middle Holocene (similar to 9500-5000 years B.P.). A data set descr ibing land-surface conditions 6000 years B.P. on a 1 degrees x 1 degre es grid across northern Africa and the Arabian Peninsula has been prep ared from published maps and other sources of palaeoenvironmental data , with the primary aim of providing a realistic lower boundary conditi on for atmospheric general circulation model experiments similar to th ose performed in the Palaeoclimate Modelling Intercomparison Project. The data set includes information on the percentage of each grid cell occupied by specific vegetation types (steppe, savanna, xerophytic woo ds/scrub, tropical deciduous forest, and tropical montane evergreen fo rest), open water (lakes), and wetlands, plus information on the flow direction of major drainage channels for use in large-scale palaeohydr ological modeling. The data set is available in digital form by anonym ous ftp.