An extreme climate transition in the Caribbean's Virgin Islands. II. Sun and Northern hemisphere atmospheric–oceanic feedbacks

Abstract

The last 60 years of extreme climate variability, and a 1980s climatic shift in the Caribbean's Virgin Islands were analysed to explore relationships with the Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO), El‐Niño Southern Oscillation (ENSO), and sunspot numbers. AMO, NAO, ENSO, and sunspot number relationships with the Virgin Islands climate were assessed from measures to their number density of statistically significant correlation with 17 extreme climate indices. Decadal daytime cooling negatively (positively) correlated with AMO (ENSO) records, while moderate nightly warming positively related to the AMO, ENSO, and NAO. In the decades following the late 1970s to early 1980s, evidence was suggestive of an increased lead time for local temperature responses. A relationship with sunspots in extreme temperature was indicated in daytime variations, at a lead time consistent with NAO influences expected from solar activity. The NAO, and to a lesser extent the ENSO, exhibited a negative association to extreme precipitation, while the AMO and sunspot number records only supported a connectivity post 1970s. Twentieth century strengthening of the tropical Atlantic tripole in sea surface temperatures is implicated as the source of decadal warming, and an increasingly rainy climate. More frequent poleward shifts of the Atlantic Intertropical Convergence Zone are suggested to explain recent decadal rises in intense rainfall events, from increased occurrences in organized deep convection.