Climate change scenarios - WP2000

Partners involved: MPI (lead contractor), LMD, DMI, CNRM, the Met Office

The aim of this work package is yo diagnose the future impacts of anthropogenic climate change on monsoon climates using existing control/scenario integrations. The application of regional models to monsoon systems will be included since they provide the higher spatial resolution needed for the impact studies involving agriculture and hydrology. The incidence of extreme events will be a particular focus of study.

Key achievements so far:

  • a new climate scenario experiment covering the 21st century has been performed using the latest version of the coupled atmosphere-ocean-sea ice model developed at CNRM. The control simulation was fairly realistic. The main changes between the 1970-2000 and 2070-2100 periods were a strong increase in the ITCZ rainbelt associated with lower precipitaiton in the winter hemisphere subtropics and an increase in monsoon rainfall over the Sahel and India.

  • the climate response over Africa for the periods 1980-2010, 2040-2070 and 2070-2100 have been analysed in detail. The warming is larger over the continents and the increase in the land-sea contrast leads to a strengthening of the hydrologic cycle nd of the monsoon circultaion.

  • time-slice experiments covering two periods: 1970-2000 and 2060-2089 (when the carbon dioxide content of the atmosphere is predicted to double) show that the increased land-sea temperature contrast in the Indian Ocean basin leads to a strengthening of the monsoon circulation

  • further time-slice experiments with a sophisticated land-surface scheme show that the simulated increase of rainfall over South India is not clearly correlated with the wind field changes and that the land surface scheme has an significant effect on the simulation of the monsoon

  • a transient greenhouse gas warming integration again show that increases of greenhouse gas concentrations intensify the Asian summer monsoon and its variability

  • changes the intrasesasonal variability of the Asian monsoon was studied by comparing model integrations with pre-industrial carbon dioxide with those with increased carbon dioxide. In the warmer future climate, the change in intraseasonal precipitation anomalies can be attributed to the change in the frequency of cyclones originating in the Bay of Bengal.

Publications on this topic by PROMISE partners

Martin, G.M. (2001) K. Arpe, F. Chauvin, L. Ferranti, K. Maynard, J. Polcher, D.B. Stephenson, P. Tschuck (2001) Simulation of the Asian Summer Monsoon in Five European General Circulation Models. Atmospheric Science Letters DOI:10.1006/asle.2000.000

Martin, G.M. 1999. The simulation of the Asian Summer Monsoon, and its sensitivity to horizontal resolution, in the UK Meteorological Office Unified Model. Q. J. R. Meteorol. Soc., 125 1499-1525

Martin, G.M. and Soman, M.K. 2000. Effects of changing physical parametrisations on the simulation of the Asian summer monsoon in the UK Meteorological Office Unified Model. Hadley Centre Technical Note No. 17 Available from The Met. Office, London Road, Bracknell, RG12 2SY, U.K. and online

Polcher, J. (1994) Etude de la sensibilite du climat tropical a la deforestation. PhD Thesis, Universite Pierre et Marie Curie, Paris VI.

Polcher, J. and Laval, K. (1994a) The impact of African and Amazonian deforestation on tropical climate. Journal of Hydrology 155:389-405.

Polcher, J. and Laval, K. (1994b) A statistical study of the regional impact of deforestation on climate in the LMD-GCM. Climate Dynamics 10:205-219.

Le Roux, X., Polcher, J., Dedieu, G., Menaut, J. C., and Monteny, B. (1994) Radiation exchanges above west african moist savannas: seasonal patterns, and comparaison with a GCM simulation. J. Geophys. Res. 99(D12):25,857-25,868.

Mechoso, C.R., Robertson, A.W., Barth, N., Davey, M.K., Delecluse, P., Gent, P.R., Ineson, S., Kirtman, B., Latif, M., Le Treut, H., Nagai, T., Neelin, J.D., Philander, S.G.H., Polcher, J., Schopf, P.S., Stockdale, T., Suarez, M.J., Terry, L., Thual, O., Tribbia, J.J. (1995). The seasonal cycle over the tropical pacific in general circulation models. Monthly Weather Review 123(9):2825-2838.

Polcher, J. (1995) Sensitivity of tropical convection to land surface processes. Journal of the Atmospheric Sciences 52(17):3143-3161.

R.C. Raghava, K. Laval, R. Sadourny, J. Polcher (1995) On the atmospheric response to the tropical denuding of vegetation. Atmospheric Environment 29, pp1963-2000.

K. Laval and J. Polcher (1995) Sensitivity of the Indian Monsoon to Land-Surface Evaporationrate in the LMD-GCM. AMIP Scientific Conference, 15-19 May 1995, Monterey, California