Climatology and Variability of the Evaporative Stress Index and its suitability as a tool to monitor Australian drought

Nguyen, Hanh and Otkin, Jason A. and Wheeler, Matthew C. and Hope, Pandora and Trewin, Blair and Pudmenzky, Christa (2020) Climatology and Variability of the Evaporative Stress Index and its suitability as a tool to monitor Australian drought. Journal of Hydrometeorology. pp. 1-37. ISSN 1525-755X


Abstract

The seasonal cycle of the Evaporative Stress Index (ESI) over Australia, and its relationship to observed rainfall and temperature, is examined. The ESI is defined as the standardized anomaly of the ratio of actual evapotranspiration to potential evapotranspiration, and as such, is a measure of vegetation moisture stress associated with agricultural or ecological drought. The ESI is computed using the daily output of version 6 of the Bureau of Meteorology's landscape water balance model (AWRA-L v6) on a 5 km horizontal grid over a 45-year period (1975-2019). Here we show that the ESI exhibits marked spatial and seasonal variability and can be used to accurately monitor drought across Australia. Values less than negative one indicate drought. While the ESI is highly correlated with rainfall as expected, its relationship with temperature only becomes significant during the warmer seasons, suggesting a threshold above which temperature may affect vegetation stress. Our analysis also shows that the ESI tends to be strongly negative (i.e. indicating drought) during El Niño and positive phases of the Indian Ocean Dipole (IOD), when conditions tend to be anomalously hot and dry. A negative phase of the Southern Annular Mode also tends to drive negative ESI values during austral spring with a one-month delay.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Life Sciences and the Environment - Centre for Applied Climate Sciences (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Life Sciences and the Environment - Centre for Applied Climate Sciences (1 Aug 2018 -)
Date Deposited: 10 Sep 2020 05:24
Last Modified: 11 Sep 2020 03:23
Uncontrolled Keywords: Evaporative Stress Index (ESI); Australia; rainfall; temperature; drought
Fields of Research (2008): 04 Earth Sciences > 0401 Atmospheric Sciences > 040107 Meteorology
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070104 Agricultural Spatial Analysis and Modelling
04 Earth Sciences > 0401 Atmospheric Sciences > 040105 Climatology (excl.Climate Change Processes)
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070101 Agricultural Land Management
Socio-Economic Objectives (2008): D Environment > 96 Environment > 9602 Atmosphere and Weather > 960202 Atmospheric Processes and Dynamics
D Environment > 96 Environment > 9602 Atmosphere and Weather > 960203 Weather
Identification Number or DOI: https://doi.org/10.1175/JHM-D-20-0042.1
URI: http://eprints.usq.edu.au/id/eprint/39450

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