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General-circulation model; lake-level fluctuations; 9000 years bp; eastern sahara; biosphere-model; lacustrine sediments; southern sahara; northwest-sudan; gcm simulation; pollen data
Abstract:
Large changes in the extent of northern sub tropical arid regions during the Holocene are attributed to orbitally forced variations in monsoon strength and have been implicated in the regulation of atmospheric trace gas concentrations on millenial timescales. Models that omit biogeophysical feedback, however, are unable to account for the full magnitude of African monsoon amplification and extension during the early to middle Holocene (similar to 9500-5000 years B.P.). A data set describing land- surface conditions 6000 years B.P. on a 1 degrees x 1 degrees grid across northern Africa and the Arabian Peninsula has been prepared from published maps and other sources of palaeoenvironmental data, with the primary aim of providing a realistic lower boundary condition for atmospheric general circulation model experiments similar to those 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 woods/scrub, tropical deciduous forest, and tropical montane evergreen forest), open water (lakes), and wetlands, plus information on the flow direction of major drainage channels for use in large-scale palaeohydrological modeling. The data set is available in digital form by anonymous ftp.
