Investigating the effect of cosmic ray (exogenic forcing) on the east and southern Africa rainfall variability

Abstract

Standardized indices of low and high frequency components of annual Cosmic Ray Fluxes (CRF) for the period 1958 to 2004 obtained from the National Geophysical Data Centre (NGDC) for three middle latitude locations of Kiel, Germany, Moscow, Russia, Climax, USA and one equatorial station of Huancayo, Peru were correlated with seasonal rainfall data of East and Southern Africa, annual average of southern oscillation and December to February sea surface temperature (SST) of equatorial Pacific and Indian Ocean. The high speed and energy transfer during the collision processes impact the atmospheric motion on the molecular to small scale. This project employs the conservation of angular momentum principle and the Stratosphere Troposphere Exchange (STE) processes between different layers of the atmosphere .amongst others to account for linkages and associations of CRF with the circulation indices and the East/Southern African summer rainfall. The use of current predictors in seasonal predictions may not have resolved the issue of accuracy hence the need for others to improve the predictability of seasonal rainfall. The eddy fluxes of the meridional momentum fluxes in the lower troposphere were found to be accountable for the significant association with East/Southern African rainfall and consistent with the variability of solar activity. The vertical and zonal component along the equatorial region may be responsible for the modulation of sea surface temperature (SST) and storm formation mainly through the high frequency and amplitude variation. The timescale within which these processes are manifested make it ideal for inclusion as predictors for long lead prediction. Canonical Correlation Analysis (CCA) prediction technique was employed with the International Research Institute (IR!) newly developed Climate Predictability Tool (CPT v.6.06) to produce sample forecast. Accuracy measures revealed improvement in forecast errors over the 1991- 1999 periods though further monitoring to evaluate" the possible use of CRF in seasonal prediction is needed and could help mitigate the impacts of east/southern Africa's fluctuating climate. Long lead predictions have considerable benefits for the climate sensitive economy of African. It is expected that an advance warning of drought risk and seasonal rainfall prospects will improve the economic growth potential of east/southern Africa and provide additional security for food and water supplies.