Assessment of GloseA4 seasonal forecasts for SADC and the global oceans

Abstract

Seasonal forecast skill over southern Africa may improve through the combination of forecasts. In the southern African region, however, only a small number of institutions have the capability to run global models operationally which can feed into multi-models. Moreover, coupled ocean-atmosphere models have the ability to outscore atmospheric models, also for southern Africa (Landman et al., 2012). The main objective of this paper is to demonstrate the skill of the UK Met Office Hadley Centre’s coupled global seasonal forecasting system (GloSea4: Arribas et al., 2011) as a seasonal forecasting tool for SADC and for the global oceans. In addition, the value of including GloSea4 forecasts into multi-model systems is tested. These investigations are conducted by testing the model’s ability to predict seasonal rainfall totals during the austral spring (SON), mid-summer (DJF) and autumn (MAM) seasons over the region, and for monthly sea-surface temperature anomalies during mid-summer. The model’s ability to simulate SADC’s intra-seasonal rainfall and low-level circulation characteristics is also investigated.