9:45 AM - 10:00 AM
[AOS17-04] On the predictability of tropical Atlantic surface winds
Keywords:tropical Atlantic, predictability, seasonal prediction, interannual variability
Observed surface zonal wind variability over the western equatorial Atlantic displays pronounced seasonality with a distinct peak in April. The SINTEX-F control simulation is able to reproduce this seasonality though the peak is delayed by one month relative to observations. The sensitivity tests suggest that, during May and June, about 80% of this variability is due to local and remote SST anomalies, while internal atmospheric processes contribute 20%. The contribution from internal variability is substantially larger in other months. Equatorial Atlantic SSTs control about 75% of the equatorial surface wind variability in June but only about 20% in boreal spring. Likewise, remote influences associated with equatorial Pacific SST anomalies contribute about 20% of equatorial Atlantic surface wind variability in spring.
The results suggest that a large portion of equatorial Atlantic wind variability in boreal spring is due to internal atmospheric processes and therefore not predictable. This may also limit the predictability of equatorial Atlantic SST variability.