The Australian Summer of 2009-2010

Nicholas Klingaman

Tropical Cyclone Ului(tracking west)

Tropical Cyclone Tomas(tracking east)

MODIS Image on 16 March 2010

Temperature and Rainfall

Anomaly in DJF-mean maximum temperature (1961-1990 climatology)

Decile of DJF-mean maximum temperature (based on 1950-2009)

Warmest summer on recordin Western Australia (since 1950) Second-

warmest summer in Tasmania

Temperature and Rainfall

Total rainfall in DJF

Percentage anomaly in DJF rainfall (based on 1900-2009 climatology)

Summer is the dry seasonin SW Australia, so discountdry anomalies here.

Exceptionally wetacross most of easternAustralia, including drought-stricken Murray-Darling Basin.

An uncharacteristic response to El Nino?

Niño 4 and rainfall for

December

Niño 4 and rainfall for

January

Niño 4 and rainfall for

February

Instantaneous correlation between monthly means of Niño 4 and SILO (gauge-based) rainfall for 1900-2008.

Red (blue) indices dry (wet) during El Niño.

Tropical Cyclone Olga

Tropical Cyclone Olga wound its wayacross northern Queensland in late January, bringing 200-300 mm of rain to nearly all of the state.

Note that the DJF total anomaly across Queensland is approximately 200 mm.

There are typically 0-3 tropical cyclones in Queensland each summer, but landfalling cyclones are approximately 3x more frequent during La Niña than during El Niño.

Climatological DJF 850 hPa wind(NCEP/NCAR)

Anomalous DJF 850 hPa wind(NCEP/NCAR)

Note the stronger westerlies south of Australia and stronger sub-tropical

easterlies, associated with Tasman Sea blocking.

850 hPa wind

Note higher pressuresin Tasman Sea between Australiaand New Zealand, as well as southwardshift of Southern Ocean storm track.

This is consistentwith blocking in the Tasman Sea, leading to dry and warm conditions over Tasmania and more cyclones penetrating into the interior of New South Wales and Queensland.

Mean sea-level pressure

High pressure over southwest Australia, combined with stronger easterlies bringing warm air from interior, has led to heatwaves in Western Australia.

500 hPa Geopotential Height

Tropical Cyclone Ului9-21 MarchDots every six hours

Intensified from Tropical Storm toCategory 5 hurricane in ~24 hours:980 hPa to 918 hPa (central pressure)65 mph to 160 mph (sustained wind)

Category 1 at landfall in Queensland.

Tropical Cyclone Ului

Tropical Cyclone Ului

Accumulated rainfall (mm) from TRMM over 15-

22 March.