Cross-season and cross-hemispheric influence of southwest Pacific SST on Arabian Peninsula precipitation

The predictability of precipitation in the Arabian Peninsula is of great importance for local agriculture and socio-economic development. In autumn, precipitation in the Arabian Peninsula is correlated with ENSO, but its predictive skill is limited. Here, we show that spring sea surface temperature (SST) anomalies in the southwest Pacific (SWP) exhibit a higher correlation with autumn precipitation in the Arabian Peninsula than ENSO, enhancing the predictability of local dry/wet variations. This cross-season and cross-hemispheric relationship is established through the western tropical Pacific (WTP). The spring SWP SST anomalies show a cross-hemispheric propagation embedded in the southerly monsoon flow by initiating the wind-evaporation-SST feedback, which sustains the progression of SST anomalies towards the WTP in autumn. The warming (cooling) of WTP SST enhances (suppresses) the convection in the Indo-western Pacific and leads to an anomalous cyclonic (anticyclonic) circulation in the northern Indian Ocean, which corresponds to northerly (southerly) anomalies and moisture divergence (convergence) over the northern Arabian Peninsula, causing precipitation decrease (increase). These results indicate that the SWP SST is a useful predictor of Arabian Peninsula precipitation six months in advance through the cross-hemispheric influence. A model based on the spring SWP SST and preceding winter ENSO (Niño3.4) shows a high predictive skill for the autumn precipitation anomalies in the Arabian Peninsula.