Near-Surface Salinity Reveals the Oceanic Sources of Moisture for Australian Precipitation through Atmospheric Moisture Transport

The long-term trend of sea surface salinity (SSS) reveals an intensification of the global hydrological cycle due to human-induced climate change. This study demonstrates that SSS variability can also be used as a measure of terrestrial precipitation on interseasonal to interannual time scales, and...

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Bibliographic Details
Published in:	Journal of climate 2020-08, Vol.33 (15), p.6707-6730
Main Authors:	Rathore, Saurabh, Bindoff, Nathaniel L., Ummenhofer, Caroline C., Phillips, Helen E., Feng, Ming
Format:	Article
Language:	eng
Subjects:	Anomalies Atmospheric moisture Atmospheric precipitations Climate change Dipoles El Nino El Nino phenomena El Nino-Southern Oscillation event Freshwater Human influences Hydrologic cycle Hydrological cycle Hydrology Inland water environment La Nina Man-induced effects Marine transportation Moisture Moisture flux Oceans Precipitation Rain Rainfall Rainfall forecasting Salinity Salinity effects Sea surface Southern Oscillation Surface salinity Terrestrial environments Transport Variability
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Summary:	The long-term trend of sea surface salinity (SSS) reveals an intensification of the global hydrological cycle due to human-induced climate change. This study demonstrates that SSS variability can also be used as a measure of terrestrial precipitation on interseasonal to interannual time scales, and to locate the source of moisture. Seasonal composites during El Niño–Southern Oscillation/Indian Ocean dipole (ENSO/IOD) events are used to understand the variations of moisture transport and precipitation over Australia, and their association with SSS variability. As ENSO/IOD events evolve, patterns of positive or negative SSS anomaly emerge in the Indo-Pacific warm pool region and are accompanied by atmospheric moisture transport anomalies toward Australia. During co-occurring La Niña and negative IOD events, salty anomalies around the Maritime Continent (north of Australia) indicate freshwater export and are associated with a significant moisture transport that converges over Australia to create anomalous wet conditions. In contrast, during cooccurring El Niño and positive IOD events, a moisture transport divergence anomaly over Australia results in anomalous dry conditions. The relationship between SSS and atmospheric moisture transport also holds for pure ENSO/IOD events but varies in magnitude and spatial pattern. The significant pattern correlation between the moisture flux divergence and SSS anomaly during the ENSO/IOD events highlights the associated ocean–atmosphere coupling. A case study of the extreme hydroclimatic events of Australia (e.g., the 2010/11 Brisbane flood) demonstrates that the changes in SSS occur before the peak of ENSO/IOD events. This raises the prospect that tracking of SSS variability could aid the prediction of Australian rainfall.
ISSN:	0894-8755 1520-0442