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Blockley Y.,Climate Information Services
Australian Meteorological and Oceanographic Journal | Year: 2015

Southern hemisphere circulation patterns and associated anomalies for austral summer 2014-15 are reviewed, with an emphasis on Pacific Basin climate indi-cators and Australian rainfall and temperature. The tropical Pacific ocean tem-perature in summer 2014-15 was just below El Niño threshold. The summer saw above average temperature in most of Australia, with the nation-wide mean temperature ranked the 6th highest on record. Summer rainfall was above aver-age nation-wide, though it was very dry in northern Queensland due to an over-all weak monsoon in the tropical western Pacific. Two tropical lows impacted the Kimberley region in Western Australia in January, and two tropical cy-clones, Lam and Marcia, made landfall in Northern Territory's Arnhem Land and Queensland's Capricorn Coast in February.

Charles A.N.,Climate Information Services | Brown J.R.,Center for Australian Weather and Climate Research | Cottrill A.,Center for Australian Weather and Climate Research | Shelton K.L.,Monash University | And 2 more authors.
Journal of Geophysical Research D: Atmospheres | Year: 2014

The position and orientation of the South Pacific Convergence Zone (SPCZ), modulated by the El Niño-Southern Oscillation (ENSO), determine many of the potentially predictable interannual variations in rainfall in the South Pacific region. In this study, the predictability of the SPCZ in austral summer is assessed using two coupled (ocean-atmosphere) global circulation model (CGCM)-based seasonal prediction systems: the Japan Meteorological Agency's Meteorological Research Institute Coupled Ocean-Atmosphere General Circulation Model (JMA/MRI-CGCM) and the Australian Bureau of Meteorology's Predictive Ocean-Atmosphere Model for Australia (POAMA-M24). Forecasts of austral summer rainfall, initialized in November are assessed over the period 1980-2010. The climatology of CGCM precipitation in the SPCZ region compares favorably to rainfall analyses over subsets of years characterizing different phases of ENSO. While the CGCMs display biases in the mean SPCZ latitudes, they reproduce interannual variability in austral summer SPCZ position indices for forecasts out to 4 months, with temporal correlations greater than 0.6. The summer latitude of the western branch of the SPCZ is predictable with correlations of the order of 0.6 for forecasts initialized as early as September, while the correlation for the eastern branch only exceeds 0.6 for forecasts initialized in November. Encouragingly, the models are able to simulate the large displacement of the SPCZ during zonal SPCZ years 1982-1983, 1991-1992, and 1997-1998. ©2014. American Geophysical Union. All Rights Reserved.

Pepler A.,Climate Information Services | Pepler A.,University of New South Wales | Timbal B.,Center for Australian Weather and Climate Research | Rakich C.,Climate Information Services | Coutts-Smith A.,Climate Information Services
Journal of Climate | Year: 2014

The strong relationship between eastern Australian winter-spring rainfall and tropical modes of variability such as the El Niño-Southern Oscillation (ENSO) does not extend to the heavily populated coastal strip east of the Great Dividing Range in southeast Australia, where correlations between rainfall and Niño-3.4 are insignificant during June-October. The Indian Ocean dipole (IOD) is found to have a strong influence on zonal wind flow during the winter and spring months, with positive IOD increasing both onshore winds and rainfall over the coastal strip, while decreasing rainfall elsewhere in southeast Australia. The IOD thus opposes the influence of ENSO over the coastal strip, and this is shown to be the primary cause of the breakdown of the ENSO-rainfall relationship in this region.

Pepler A.S.,Climate Information Services | Trewin B.,Climate Information Services | Ganter C.,Climate Information Services
Australian Meteorological and Oceanographic Journal | Year: 2015

The El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Southern Annular Mode (SAM) are all widely recognised as having significant impacts on rainfall and temperatures in southeastern Australia, particularly dur-ing winter and spring. However, there has been little analysis of the year-to-year impact of these climate drivers on Australian snow depths. This paper aims to address this gap, identifying a strong decrease in snow cover throughout the winter season during years of El Niño or positive SAM, with significant changes in late winter and spring snow cover related to the state of the Indian Ocean Di-pole. Temperatures are identified as the most important factor in determining the seasonal maximum snow depth, with important implications for future snow cover as a result of a strong warming trend.

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