Tropical Atlantic Contributions to Strong Rainfall Variability Along the Northeast Brazilian Coast

Figure 5

Distributions of lagged linear regression coefficients (1974–2008) between the interannual rainfall anomalies for very wet (>+0.5) and very dry (<−0.5) years in Recife-ENEB (red star) during June-July, and the interannual SST anomalies during the years selected above in the tropical Atlantic for June-July (zero lag), May-June, April-May, March-April, and February-March (4-month lag) (mm·month⁻¹/°C). The vectors (mm·month⁻¹/m²·s⁻²) represent linear regressions between the interannual rainfall anomalies and the interannual PWS (PWSx and PWSy) anomalies. The 95% significance level of correlation, according to a student -test (and higher than 0.5), is plotted with a dotted line (negative) and a solid line (positive) for SSTA. Before averaging and plotting by 2-month periods, the linear trends are removed from all anomalies. The black box (SAWP) relative to May-June (MJ) represents a strongly influential SST variability area. The SAWP, which shows an inversion of the surface wind anomaly and a positive correlation of SSTA in May-June, is used in the following for testing the forecasts of the rainfall season over ENEB.