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science and station resupply cruises are very much reliant on accurate weather forecasts of up to around 2 days, yet the Southern Ocean is the most data-sparse region of the world, with the limited in situ data making ocean route forecasting difficult. Finally, Mawson Station sits at the base of a very steep coastal escarpment and is prone to a persistent and strong katabatic flow, which can often exceed 20 m s −1 and cause problems for outdoor activities. During the summer months, the surface wind
science and station resupply cruises are very much reliant on accurate weather forecasts of up to around 2 days, yet the Southern Ocean is the most data-sparse region of the world, with the limited in situ data making ocean route forecasting difficult. Finally, Mawson Station sits at the base of a very steep coastal escarpment and is prone to a persistent and strong katabatic flow, which can often exceed 20 m s −1 and cause problems for outdoor activities. During the summer months, the surface wind
the January–February–March (JFM) 2000 rainfall over southern Namibia resulted from this system; thus, it made a very significant contribution to the seasonal total. Eline was the longest-lived tropical storm observed in the southwest Indian Ocean (SWIO) to date, had an unusually zonal track, and penetrated exceptionally far inland over the interior plateau of southern Africa. Note that less than 5% of TCs occurring in the SWIO over the last 50 years have actually made landfall on the east coast of
the January–February–March (JFM) 2000 rainfall over southern Namibia resulted from this system; thus, it made a very significant contribution to the seasonal total. Eline was the longest-lived tropical storm observed in the southwest Indian Ocean (SWIO) to date, had an unusually zonal track, and penetrated exceptionally far inland over the interior plateau of southern Africa. Note that less than 5% of TCs occurring in the SWIO over the last 50 years have actually made landfall on the east coast of
1. Introduction The Working Group on Physics and Chemistry of the Atmosphere (PACA) of the Scientific Committee on Antarctic Research (SCAR) initiated the concept of the Antarctic First Regional Observing Study of the Troposphere (FROST; see Turner et al. 1996 ). The Hobart office of the Australian Bureau of Meteorology, the Institute of Antarctic and Southern Ocean Studies and the Antarctic Cooperative Research Centre at the University of Tasmania, the British Antarctic Survey (BAS), and the
1. Introduction The Working Group on Physics and Chemistry of the Atmosphere (PACA) of the Scientific Committee on Antarctic Research (SCAR) initiated the concept of the Antarctic First Regional Observing Study of the Troposphere (FROST; see Turner et al. 1996 ). The Hobart office of the Australian Bureau of Meteorology, the Institute of Antarctic and Southern Ocean Studies and the Antarctic Cooperative Research Centre at the University of Tasmania, the British Antarctic Survey (BAS), and the
of the NOAA/OPC, the Perth RFC and TCWC regard the QuikSCAT data as one of the key marine weather and oceanographic datasets available to it. At times, it provides the sole basis for the issuance of warnings for severe marine weather and ocean conditions. Given that the Indian Ocean occupies the entire region from the coast of Western Australia across to the African continent and the Southern Ocean from the southern coastline of Australia southward to Antarctica, the identification of the
of the NOAA/OPC, the Perth RFC and TCWC regard the QuikSCAT data as one of the key marine weather and oceanographic datasets available to it. At times, it provides the sole basis for the issuance of warnings for severe marine weather and ocean conditions. Given that the Indian Ocean occupies the entire region from the coast of Western Australia across to the African continent and the Southern Ocean from the southern coastline of Australia southward to Antarctica, the identification of the
prefrontal westerly trough of southern Australia is presented, based on data for the 10yr period 1976-85. Trough formation was confined to the longitudes of the Australian continent in the warmermonths of the year. An average of approximately 15 troughs/yr were observed, evenly distributed each month -from September to April, with appreciable interannual variability in incidence. Troughs formed in advance ofa major Southern Ocean cold front in a region of differential thermal advection. Genesis occurred
prefrontal westerly trough of southern Australia is presented, based on data for the 10yr period 1976-85. Trough formation was confined to the longitudes of the Australian continent in the warmermonths of the year. An average of approximately 15 troughs/yr were observed, evenly distributed each month -from September to April, with appreciable interannual variability in incidence. Troughs formed in advance ofa major Southern Ocean cold front in a region of differential thermal advection. Genesis occurred
increased SST in the Indian, South Atlantic, and eastern tropical Pacific Oceans. A more gradual Sahelian drying has paralleled a warming ( cooling) of the Southern ( Northern) Hemisphere SST, particularly in the Atlantic. Parts of southern Africa's summer rainfall is enhanced by positive SST anomalies in the adjacent South Atlantic and southwest Indian Oceans but sup- pressed by generalized warm worldwide SST. Wet season rainfall at a small minority of stations in eastern Africa is increased by
increased SST in the Indian, South Atlantic, and eastern tropical Pacific Oceans. A more gradual Sahelian drying has paralleled a warming ( cooling) of the Southern ( Northern) Hemisphere SST, particularly in the Atlantic. Parts of southern Africa's summer rainfall is enhanced by positive SST anomalies in the adjacent South Atlantic and southwest Indian Oceans but sup- pressed by generalized warm worldwide SST. Wet season rainfall at a small minority of stations in eastern Africa is increased by
classic climate indices and ultimately describe the large-scale circulation in a similar fashion (e.g., Klotzbach and Gray 2004 ; Goebbert and Leslie 2010 ). Most of the research on TCs, especially seasonal prediction, occurs for regions in the Northern Hemisphere. Southern Hemispheric storms, which occur in the Indian and southwest Pacific Oceans, are not as well covered in the literature. There are two primary TC basins in the Southern Hemisphere: the southern Indian Ocean basin and the Australian
classic climate indices and ultimately describe the large-scale circulation in a similar fashion (e.g., Klotzbach and Gray 2004 ; Goebbert and Leslie 2010 ). Most of the research on TCs, especially seasonal prediction, occurs for regions in the Northern Hemisphere. Southern Hemispheric storms, which occur in the Indian and southwest Pacific Oceans, are not as well covered in the literature. There are two primary TC basins in the Southern Hemisphere: the southern Indian Ocean basin and the Australian
. 2012 ) and midlatitude (e.g., Reason and Rouault 2005 ) weather systems, as well as by the interaction of weather systems from these two distinct circulation regimes (e.g., Hart et al. 2010 ). The domain over which forecast circulation anomalies are evaluated is thus chosen to include the important geographical regions from where weather systems develop and propagate to influence the southern African region. These include the regions of maximum cyclogenesis over the southwestern Atlantic Ocean
. 2012 ) and midlatitude (e.g., Reason and Rouault 2005 ) weather systems, as well as by the interaction of weather systems from these two distinct circulation regimes (e.g., Hart et al. 2010 ). The domain over which forecast circulation anomalies are evaluated is thus chosen to include the important geographical regions from where weather systems develop and propagate to influence the southern African region. These include the regions of maximum cyclogenesis over the southwestern Atlantic Ocean
evident in this difference field; namely, October-mean 500-mb heights are lower (higher), on average, near 40°N, 130°W (25°N, 115°W) before very active seasons than before very inactive seasons. The geostrophic zonal wind field (not shown) calculated from Fig. 4 reveals stronger October-mean geostrophic westerly winds over the subtropical Pacific Ocean and southern United States preceding very active seasons than before very inactive seasons. The large positive height difference over the Gulf of
evident in this difference field; namely, October-mean 500-mb heights are lower (higher), on average, near 40°N, 130°W (25°N, 115°W) before very active seasons than before very inactive seasons. The geostrophic zonal wind field (not shown) calculated from Fig. 4 reveals stronger October-mean geostrophic westerly winds over the subtropical Pacific Ocean and southern United States preceding very active seasons than before very inactive seasons. The large positive height difference over the Gulf of
onset (relative to the climatological average) using the antecedent July–August Southern Oscillation index (SOI) as the predictor, showing useful skill. Here, we examine the long-range prediction of onset at lead times of up to 3 months using the Predictive Ocean–Atmosphere Model for Australia (POAMA), the Bureau of Meteorology’s coupled prediction system. As we show below, we are able to achieve greater prediction skill than the statistical method of Lo et al. (2007) . 2. Data and modeling method
onset (relative to the climatological average) using the antecedent July–August Southern Oscillation index (SOI) as the predictor, showing useful skill. Here, we examine the long-range prediction of onset at lead times of up to 3 months using the Predictive Ocean–Atmosphere Model for Australia (POAMA), the Bureau of Meteorology’s coupled prediction system. As we show below, we are able to achieve greater prediction skill than the statistical method of Lo et al. (2007) . 2. Data and modeling method
