On the drivers of inter‐annual and decadal rainfall variability in Queensland, Australia

Abstract

Queensland experiences considerable inter-annual and decadal rainfall variability, which impacts waterresource management, agriculture and infrastructure. To understand the mechanisms by which large-scale atmospheric and coupled air-sea processes drive these variations, empirical orthogonal teleconnection (EOT) analysis is applied to 1900-2010 seasonal Queensland rainfall. Fields from observations and the 20th Century Reanalysis are regressed onto the EOT timeseries to associate the EOTs with large-scale drivers. In winter, spring and summer the leading, state-wide EOTs are highly correlated with the El Niño-Southern Oscillation (ENSO); the Inter-decadal Pacific Oscillation modulates the summer ENSO teleconnection. In autumn, the leading EOT is associated with locally driven, late-season monsoon variations, while ENSO affects only tropical northern Queensland. Examining EOTs beyond the first, southeastern Queensland and the Cape York peninsula emerge as regions of coherent rainfall variability. In the southeast, rainfall anomalies respond to the strength and moisture content of onshore easterlies, controlled by Tasman Sea blocking. The summer EOT associated with onshore flow and blocking has been negative since 1970, consistent with the observed decline in rainfall along the heavily populated coast. The southeastern Queensland EOTs show considerable multi-decadal variability, which is independent of large-scale drivers. Summer rainfall in Cape York is associated with tropical-cyclone activity.

Disentangling the Multiple Sources of Large-Scale Variability in Australian Wintertime Precipitation

“…Precipitation exhibits a broad scale of variability extending from the interseasonal to interdecadal time scales and from synoptic to planetary spatial scales, teleconnecting from tropical to extratropical latitudes Klingaman et al 2013;Allen et al 2009;Cai et al 2011a). While model studies assist in causal attribution of precipitation change, current global atmospheric models are often poor at simulating regional precipitation.…”

Interannual rainfall variability over China in the MetUM GA6 and GC2 configurations

“…The EOT method identifies independent regional patterns of coherent rainfall variability. The associated time series can be used to connect the patterns to regional and large-scale atmospheric and coupled atmosphereocean mechanisms, as Stephan et al (2017a, b) demonstrated for China and as was previously shown for other regions (Smith, 2004;Rotstayn et al, 2010;Klingaman et al, 2013;King et al, 2014).…”

A comprehensive analysis of coherent rainfall patterns in China and potential drivers. Part II: intraseasonal variability

“…The EOT method has been successfully demonstrated for interannual precipitation variability (Smith 2004;Rotstayn et al 2010;Klingaman et al 2013;King et al 2014) and for intraseasonal extreme precipitation (King et al 2014). In Part I of this study (Stephan et al 2017) the method was shown to successfully reproduce known patterns of interannual precipitation variability in China.…”