Tim Cowan, Emily Hinds, Andrew G. Marshall, Matthew C. Wheeler, Catherine de Burgh-Day
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引用次数: 0
Abstract
According to the Australian Bureau of Meteorology, the northern Australian wet season extends through to April, which also formally marks the end of Australia’s tropical cyclone season. Mid-autumn is when the tropical dry season transition period begins, when crop farmers prepare land for annual crops or pasture–fodder harvest, or when beef cattle producers make decisions regarding stock numbers and feed rationing. Potentially knowing if the last rains of the wet season will be later or earlier than normal would be valuable information for northern sectors such as agriculture, infrastructure and tourism. The Bureau of Meteorology provides seasonal forecasts of the Northern Rainfall Onset – the date when a location has accumulated 50 mm of rain from 1 September – yet there is currently no prediction of the rainy season retreat (the Northern Rainfall Retreat, NRR). In this study, we draw on three different NRR definitions and investigate how they vary with the El Niño–Southern Oscillation and the Madden–Julian Oscillation (MJO). In general, retreats occur ~1 week later than normal across the far northern tropics following La Niña events, but little change from normal occurs for El Niño. Although most retreats occur when the MJO is weak, if the MJO is active, retreats are mostly observed in phases 6 and 7, when convection is passing through the western Pacific. Utilising the Bureau of Meteorology’s sub-seasonal to seasonal forecast system, ACCESS-S2, we show that the model has some skill in forecasting the NRR across the far northern regions at a lead time of ~2.5 months, but poor skill in the subtropics and arid locations. Verification of the 2023 NRR forecasts, highlights the challenges of predicting the timing and magnitude of daily rainfall at such a long lead time.
期刊介绍:
The Journal of Southern Hemisphere Earth Systems Science (JSHESS) publishes broad areas of research with a distinct emphasis on the Southern Hemisphere. The scope of the Journal encompasses the study of the mean state, variability and change of the atmosphere, oceans, and land surface, including the cryosphere, from hemispheric to regional scales.
general circulation of the atmosphere and oceans,
climate change and variability ,
climate impacts,
climate modelling ,
past change in the climate system including palaeoclimate variability,
atmospheric dynamics,
synoptic meteorology,
mesoscale meteorology and severe weather,
tropical meteorology,
observation systems,
remote sensing of atmospheric, oceanic and land surface processes,
weather, climate and ocean prediction,
atmospheric and oceanic composition and chemistry,
physical oceanography,
air‐sea interactions,
coastal zone processes,
hydrology,
cryosphere‐atmosphere interactions,
land surface‐atmosphere interactions,
space weather, including impacts and mitigation on technology,
ionospheric, magnetospheric, auroral and space physics,
data assimilation applied to the above subject areas .
Authors are encouraged to contact the Editor for specific advice on whether the subject matter of a proposed submission is appropriate for the Journal of Southern Hemisphere Earth Systems Science.