Australian Monsoon Monitoring
15-day run-mean NAus rainfall
Northern Australian rainfall in this austral summer-centered year (from August to July) averaged over the land domain in [25°S–10°S, 120°E–145°E] (following Sekizawa et al. 2023). Thin black and thick pink lines indicate the daily rainfall and its 15-day running mean, respectively. Grey line denotes the climatological average of 15-day running mean rainfall for 1958–2021, with its interannual variability represented with dark and light shadings between the lowest and highest quartiles (25th-75th percentile range) and between the lowest and highest deciles (10th-90th percentile range), respectively. Red and blue lines indicate the composited rainfall for the 20 strongest and weakest Australian monsoon years, respectively, extracted based on the January-February rainfall for 1958–2021. Rainfall data has been obtained from the Australian Bureau of Meteorology.

About the Australian monsoon

Seasonal evolution of the northern Australian rainfall shows distinct rainy season (November to April) and dry season (May to October). In the core of rainy season, easterly trade winds are replaced by westerly monsoonal winds, which bring a large amount of rainfall, about half of the annual rainfall. The summertime westerly winds, or the period or phenomenon in which they prevail, is referred to as the Australian (summer) monsoon. The Australian monsoon typically starts in late December and lasts through the beginning of March (e.g., Suppiah 1992; Drosdowsky 1996; Kajikawa et al. 2010).

The interannual variability of the Australian monsoon is not only important for agriculture and livestock industry in tropical Australia, but also has cross-equatorial influences on the East Asian wintertime climate. Sekizawa et al. (2021) revealed that the stronger (weaker) Australian monsoon intensifies (suppresses) the East Asian winter monsoon, while it decreases (increases) the Okhotsk sea-ice concentration. Australian monsoon activity is partially correlated with La Niña, but internal variability locally confined within the monsoon system dominates (Sekizawa et al. 2018; 2023).

On intraseasonal time scales, northern Australian rainfall exhibits large variability. Indeed, the summer monsoon season often consists of multiple active monsoon periods (monsoon burst events) and monsoon breaks in between, associated with midlatitude atmospheric disturbances in the Southern Hemisphere (Berry & Reeder 2016; Narsey et al. 2017) and the Madden-Julian Oscillation (MJO) in the tropics (Hendon & Liebmann 1990; Wheeler et al. 2009).


Archives (links to png files)

1959 1960 1961 1962 1963 1964
1965 1966 1967 1968 1969 1970
1971 1972 1973 1974 1975 1976
1977 1978 1979 1980 1981 1982
1983 1984 1985 1986 1987 1988
1989 1990 1991 1992 1993 1994
1995 1996 1997 1998 1999 2000
2001 2002 2003 2004 2005 2006
2007 2008 2009 2010 2011 2012
2013 2014 2015 2016 2017 2018
2019 2020 2021 2022 2023

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