Preprints
https://doi.org/10.5194/acp-2020-1206
https://doi.org/10.5194/acp-2020-1206

  15 Dec 2020

15 Dec 2020

Review status: a revised version of this preprint is currently under review for the journal ACP.

Assessing the contribution of ENSO and MJO to Australian dust activity based on satellite and ground-based observations

Yan Yu1 and Paul Ginoux2 Yan Yu and Paul Ginoux
  • 1Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, NJ 08540, USA
  • 2NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA

Abstract. Despite Australian dust's critical role in the regional climate and surrounding marine ecosystems, the controlling factors of the spatio-temporal variations of Australian dust are not fully understood. Here we assess the connections between observed spatial-temporal variations of Australian dust with key modes of large-scale climate variability, namely the El Niño-Southern Oscillation (ENSO) and Madden-Julian Oscillation (MJO). Multiple dust observations from Aerosol Robotic Network (AERONET), weather stations, and satellite instruments, namely the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) are examined. The assessed multiple dust observations consistently identify the natural and agricultural dust hotspots in Australia, including the Lake Eyre Basin, Lake Torrens Basin, Lake Frome Basin, Simpson Desert, Barwon-Darling Basin, Riverina, Barkly Tableland, and lee side of the Great Diving Range, as well as a country-wide, austral spring-to-summer peak in dust activity. Our regression analysis of observed dust optical depth (DOD) upon an ocean Niño index confirms previous model-based finding on the enhanced dust activity in southern and eastern Australia during the subsequent austral spring and summer dust season following the strengthening of austral wintertime El Niño. Our analysis further indicates the modulation of the ENSO-dust relationship with the MJO phases. During sequential MJO phases, the dust-active center moves from west to east associated with the eastward propagation of MJO, with maximum enhancement in dust activity at about 120° E, 130° E, and 140° E corresponding to MJO phases 1–2, 3–4, and 5–6, respectively. MJO phases 3–6 are favorable for enhanced ENSO modulation of dust activity, especially the occurrence of extreme dust events, in southeastern Australia, currently hypothesized to be attributed to the interaction between MJO-induced anomalies in convection and wind and ENSO-induced anomalies in soil moisture and vegetation.

Yan Yu and Paul Ginoux

 
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Status: final response (author comments only)
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Yan Yu and Paul Ginoux

Yan Yu and Paul Ginoux

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Short summary
Despite Australian dust's critical role in the regional climate and surrounding marine ecosystems, the controlling factors of its spatio-temporal variations are not fully understood. This study establishes the connection between large-scale climate variability and regional dust emission, leading to a better understanding of the spatio-temporal variation in dust activity and improved prediction of dust's climate and ecological influences.
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