Global teleconnections in droughts caused by oceanic and atmospheric circulation patterns

Abstract

Long-duration droughts are usually tied to persistent local or remote forcings; for example, persistent droughts over California are frequently observed along with the 'ridiculously resilient ridge' over the West Coast. It is now evident that some oceanic forcings (e.g. El Nino-Southern Oscillation) have global reaches and affect multiple regions concurrently during their progression. Here, we show robust significant temporal concordancy of persistent droughts in many regions, revealing multiple teleconnections (distant regions experiencing droughts concurrently), such as the 'Western North America-Mediterranean (WNA-MED)' and the 'Southeast Asia-Southern Africa (SEA-SAF)' teleconnections. Composite pressure and sea surface temperature anomalies during concurrent droughts in WNA and the MED reveal a persistent weather regime that resembles the positive phase of Arctic Oscillation and negative phase of Pacific Decadal Oscillation. During concordant droughts of SEA and SAF, composite pressure anomalies remarkably resemble the El Nino pattern, which we infer as the leading cause of the teleconnection. The insights gained here offer a new dimension to understanding droughts and improving their long-term predictability. © 2020 The Author(s). Published by IOP Publishing Ltd.