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Herraiz-Borreguero L.,University of Tasmania | Herraiz-Borreguero L.,CSIRO | Herraiz-Borreguero L.,Australian Antarctic Division | Rintoul S.R.,Center for Australian Weather | And 2 more authors.
Ocean Dynamics | Year: 2011

The subduction and export of subantarctic mode water (SAMW) as part of the overturning circulation play an important role in global heat, freshwater, carbon and nutrient budgets. Here, the spatial distribution and export of SAMW is investigated using Argo profiles and a climatology. SAMW is identified by a dynamical tracer: a minimum in potential vorticity. We have found that SAMW consists of several modes with distinct properties in each oceanic basin. This conflicts with the previous view of SAMW as a continuous water mass that gradually cools and freshens to the east. The circulation paths of SAMW were determined using (modified) Montgomery streamlines on the density surfaces corresponding with potential vorticity minima. The distribution of the potential vorticity minima revealed "hotspots" where the different SAMW modes subduct north of the Subantarctic Front. The subducted SAMWs follow narrow export pathways into the subtropical gyres influenced by topography. The export of warmer, saltier modes in these "hotspots" contributes to the circumpolar evolution of mode water properties toward cooler, fresher and denser modes in the east. © 2010 Springer-Verlag. Source

Brassington G.B.,Center for Australian Weather
Geophysical Research Letters | Year: 2013

A novel extension to time-lagged ensemble forecasting called multicycle ensemble forecasting improves the independent sampling of forecast model errors. Multicycle is defined such that each forecast cycle is independent of the previous forecast cycle. For an M cycle system the background field for each cycle is from a model hindcast M cycles earlier. The model errors have a factor M longer period to grow compared with a sequential system; however, the increased independence in the forecast model errors provide weighted ensemble averages with greater skill and reliability over the 0 lag forecast and a good spread-error relationship. This cost-efficient technique is relevant to global ocean forecasting where an ensemble method is computationally prohibitive. Key Points Multicycle is a novel extension to time-lagged ensemble forecasting Efficient sampling of random forecast model errors Weighted ensemble averages have improved skill and reliability ©2013. American Geophysical Union. All Rights Reserved. Source

Power S.B.,Center for Australian Weather | Delage F.,Center for Australian Weather
Bulletin of the American Meteorological Society | Year: 2011

A review of the number of searches made for the terms weather, weather forecast, the Bureau of Meteorology (BoM), for online weather services in Australia, is presented. In searches for BoM, the search frequency in summer is about 180% greater than the corresponding value in winter. It is also found that the evolution of the search frequencies for terms such as bushfire, flood, and tropical cyclone, does not bear any resemblance to the cyclic plots. More research is needed to confirm that participation in outdoor activities is the main reason for the annual cycles. Most of the time series of search frequencies for weather and related terms also display positive trends. While Australia's population has grown from 20,127,400 in 2004 to an estimated 22,336,133 in May 2010, this would be expected to drive similar trends in searches for weather, outdoor, or any other searches. Source

Power S.B.,Center for Australian Weather | Schiller A.,CSIRO | Cambers G.,CSIRO | Jones D.,National Climate Center | Hennessssy K.,CSIRO
Bulletin of the American Meteorological Society | Year: 2011

The Pacific Climate Change Science Program (PCCSP) is a $20 million program helping 14 developing island countries in the Pacific and East Timor gain a better understanding of climate changes. The PCCSP, which runs to the end of December 2011, is part of a much broader $150 million Australian government program, International Climate Change Adaptation Initiative (ICCAI), aimed at meeting the high-priority climate adaptation needs in the partner countries. The research in the PCCSP is being conducted in four key areas that include climate data and trends, regional climate drivers, climate change projections, and ocean processes and projections. The PCCSP is working to enhance the understanding of climate change science in partner countries through capacity building. The PCCSP is also establishing and strengthening links with research providers in regional agencies, partner countries, New Zealand, the United States, and France. Source

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