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Inter‐ and Intra‐annual precipitation variability and associated relationships to ENSO and the IOD in southern Africa
Author(s) -
Gaughan Andrea E.,
Staub Caroline G.,
Hoell Andrew,
Weaver Ariel,
Waylen Peter R.
Publication year - 2015
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.4448
Subject(s) - indian ocean dipole , climatology , precipitation , el niño southern oscillation , environmental science , teleconnection , wet season , arid , anomaly (physics) , forcing (mathematics) , atmospheric circulation , geography , geology , paleontology , physics , cartography , condensed matter physics , meteorology
Precipitation variability at inter‐ and intra‐annual scales may influence land‐use management decisions in semi‐arid savannas worldwide, and in particular, over the Kavango‐Zambezi Transfrontier Conservation Area ( KAZA ) in southern Africa. Over KAZA , spatiotemporal precipitation variability forced by the El Niño Southern Oscillation ( ENSO ) and the Indian Ocean Dipole ( IOD ) is important to local and regional‐scale decisions for planting, livestock grazing, and wildlife migration patterns. We investigate the annual water year (October–September) and early rainy season [October–November–December ( OND )] precipitation patterns during 60 years before and after a 1970s shift in the global ocean–atmosphere system for this region in southern Africa. The coincidence of the number of wet (upper tercile) and dry (lower tercile) years and OND seasons during the various phases of ENSO and IOD are compared prior to (1950–1975) and after (1980–2008) the 1970s climate shift over KAZA . Since the 1970s climate shift, KAZA has been significantly drier and observed fewer wet years and OND seasons. ENSO is the dominant forcing of precipitation differences over southern Africa before and after the 1970s climate shift, with IOD playing a secondary role. However, when ENSO and IOD phases are analysed simultaneously, El Niño and positive IOD events are significantly related to dry periods. The forcing of atmospheric circulation over southern Africa before and after the 1970s climate shift during El Niño and La Niña events is significantly different. Prior to the 1970s climate shift, atmospheric circulation during El Niño (La Niña) favoured strong (weak) precipitation increases (decreases). Afterward the 1970s climate shift, atmospheric circulation during La Niña (El Niño) favoured strong (weak) precipitation decreases (increases). The shifting nature of climate modes, especially ENSO , and respective influence on rainfall variability for southern Africa is important to understand to better inform seasonal climate forecasts to improve operational decision‐making for land‐use and water management decisions in semi‐arid savanna regions.