Passive Suppression of South African Rainfall by the Agulhas Current

Earth Interactions

Mark R.Jury¹ 

关键词: Atmosphere–ocean interaction;    Boundary currents;    ENSO;   

DOI  :  10.1175/EI-D-15-0017.1

学科分类：地球科学(综合)

来源: American Geophysical Union

【 摘 要 】

AbstractThis study reconsiders the role of the Agulhas Current in South African climate variability. Here, the Agulhas Current is delimited by its anticyclonic looping flow and cluster analysis of detrended SST anomalies that lead to an area 28°–37°S, 18°–35°E, poleward of South Africa. Regression of detrended Agulhas SST with rainfall anomaly fields in the years 1950–2012 yields a surprising negative influence over the interior. In summer, the negative regression exhibits a northwest axis consistent with reduced cloud band activity. Positive influence is confined to the eastern escarpment in the September–November season when cutoff lows are prevalent. The overall negative influence of the Agulhas SST is confirmed by regression with the vegetation fraction and latent heat flux in the satellite era.Mechanisms of South African rainfall suppression were investigated. The Agulhas SST index is positively related to the multivariate ENSO index at the 1–3-month lead time. Hence, warm years in the Agulhas Curren...

【 授权许可】

Unknown