MOTIF Diagnostic For Mid-Holocene Precipitation Over Northern Africa

Data description

Pollen evidence indicates that grassland and xerophytic woodland/scrubland occurred in ares of northern Africa characterised by desert today during the mid-Holocene (Jolly et al., 1998a, 1998b). Mid-Holocene pollen assemblages for sites south of 23° N do not contain taxa with desert affinities (Dominique Jolly, unpublished analyses), indicating that the region south of 23° N was characterised by grassland not desert.

The increase in mean annual precipitation required to support grassland at each latitude from 0 to 30° N compared to the modern precipitation at that latitude, zonally averaged over the range 20° W to 30° E longitude, has been calculated using the water-balance module from the BIOME3 equilibrium vegetation model (Haxeltine and Prentice, 1996) (see Joussaume et al., 1999). The latitudinal distribution of biomes (reconstructed at individual pollen sites) in northern Africa today and during the mid-Holocene (6000 ±500 yr B.P.) are shown on the graphic below. The grey-shaded area on the graphic shows maximum and minimum estimates of the increase in precipitation required to support grassland at each latitude. To use this graphic as a model benchmark, simulated DeltaP is required to lie above/within the grey band at all latitudes from 0-23° N.

(Click on the figure to get a bigger version)

Data download

If you wish to use these data as a diagnostic, please cite Joussaume et al. (1999) as the first application, and the following website http://www.bridge.bris.ac.uk/pmip2/synth/index.htm as the source.

References

1. Jolly, D., Harrison, S. P., Damnati, B., and Bonnefille, R. (1998a). Simulated climate and biomes of Africa during the Late Quaternary: Comparison with pollen and lake status data. Quaternary Science Reviews 17(6-7), 629-657.
   
   
2. Jolly, D., Prentice, I. C., Bonnefille, R., Ballouche, A., Bengo, M., Brenac, P., Buchet, G., Burney, D., Cazet, J. P., Cheddadi, R., Edorh, T., Elenga, H., Elmoutaki, S., Guiot, J., Laarif, F., Lamb, H., Lezine, A. M., Maley, J., Mbenza, M., Peyron, O., Reille, M., Reynaud-Farrera, I., Riollet, G., Ritchie, J. C., Roche, E., Scott, L., Ssemmanda, I., Straka, H., Umer, M., Van Campo, E., Vilimumbalo, S., Vincens, A., and Waller, M. (1998b). Biome reconstruction from pollen and plant macrofossil data for Africa and the Arabian peninsula at 0 and 6000 years. Journal of Biogeography 25(6), 1007-1027.
   
   
3. Haxeltine, A., and Prentice, I. C. (1996). BIOME3: an equilibrium terrestrial biosphere model based on ecophysiological constraints, resource availability, and competition among plant functional types. Global Biogeochemical Cycles 10(4), 693-709.
   
   
4. Joussaume, S., Taylor, K. E., Braconnot, P., Mitchell, J. F. B., Kutzbach, J. E., Harrison, S. P., Prentice, I. C., Broccoli, A. J., Abe-Ouchi, A., Bartlein, P. J., Bonfils, C., Dong, B., Guiot, J., Herterich, K., Hewitt, C. D., Jolly, D., Kim, J. W., Kislov, A., Kitoh, A., Loutre, M. F., Masson, V., McAvaney, B., McFarlane, N., de Noblet, N., Peltier, W. R., Peterschmitt, J. Y., Pollard, D., Rind, D., Royer, J. F., Schlesinger, M. E., Syktus, J., Thompson, S., Valdes, P., Vettoretti, G., Webb, R. S., and Wyputta, U. (1999). Monsoon changes for 6000 years ago: Results of 18 simulations from the Paleoclimate Modeling Intercomparison Project (PMIP). Geophysical Research Letters 26(7), 859-862.