Abstract
Precipitation teleconnections with large-scale ocean-atmosphere oscillation systems provide useful information for water management. Here we present a seven-year lag response in South Australia (SA) precipitation to the Southern Annular Mode (SAM) in a positive Interdecadal Pacific Oscillation (IPO) phase. This teleconnection between a positive SAM phase and increased SA precipitation, and vice-versa, statistically consists of three sequential steps : a 27-season lag positive correlation between sea subsurface potential temperature (SSPT) to the south of SA and SAM; a zero-season lag positive correlation between sea surface temperature (SST) and SSPT; and a 2-season positive lag correlation between SA precipitation and SST. Physically, this teleconnection seems to be associated with a supergyre circulation of the Southern Hemisphere Oceans, which transfers SAM signal via subsurface potential sea temperature in the central south Pacific to the south of SA in 27 seasons during the positive IPO phase. Practically, this teleconnection provides a 7-year-lead drought precursor for rain-fed agriculture planning in South Australia. However, the teleconnection disappears in negative IPO phases. The oceanic pathway via the supergyre suggested in this study provides a basis to predict when this seven-year teleconnection may resume in the future based on observation and/or modelling.
Highlights
Precipitation provides water on land to support ecosystem functions and societal development
This study documents a possible 7-year lag teleconnection for precipitation in South Australia, in its rain-fed agriculture region, during a positive IOP phase. This teleconnection is composed of three sequential steps: a 27season lag positive connection between sea subsurface potential temperature (SSPT) off coast of SA and Southern Annular Mode (SAM), a zero-season lag positive connection between sea surface temperature (SST) and SSPT, and a 2-season lag positive connection between precipitation in SA and SST
The 29-season lag response between South Australia precipitation and SAM is likely related to an oceanic supergyre in the southern hemisphere oceans
Summary
Precipitation provides water on land to support ecosystem functions and societal development. Largely associated with precipitation interannual variability, can lead to ecosystem and societal disasters (McDowell et al, 2008; van DijK et al, 2013). A reliable prediction of regional rainfall beyond monthly time scale is beneficial for water resource management and agricultural planning. In some areas, such as Australia (www.forecasts4profit.com.au), seasonal rainfall prediction has been routinely communicated to farmers and agricultural business operators. Statistical relationships between precipitation of a region and large-scale climate oscillation systems, in addition to atmospheric modeling, provide useful information for drought and its impact predictions, in agriculture (Bonner et al, 2014; Lu et al, 2017)
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