10 February 2009

Victorian Bushfires

Here are some stories regarding the Victorian bushfires of 7 Feb 2009, the worst bushfire loss of life in the nation's history:

In addition to the devastating fires to the northeast of Melbourne,other damaging bushfires were seen in other areas of the state. Fires in eastern Gippsland have been burning for some time, flaring spectacularly in late January. A bushfire near Horsham in the western part of the state burned over 3000 ha and seven homes. Several bushfires burned near Bendigo in the north, destroying over 69 houses. Widespread wildfire activity was also observed in NSW, including one in excess of 1000 ha in size. Many of these fires continued to burn through Monday.

These fires come in hand with what is in all likelihood the most extreme day of weather observed in Victoria. Afternoon temperatures in vicinity of Melbourne were at all-time record highs, in excess of 46 C. With relative humidity below 10% and strong, gusty NW winds, fire danger indicies were extreme, amongst the highest on record. In the past, days with this level of fire danger have often meant disaster, with fatalities and/or catastrophic house loss.

The first image is a MODIS 721 false colour image. The image, extracted from the NASA Rapid Response subset site was captured on the 7th from the Aqua satellite at just before 1600 local time. The pixel size in 250 m. *For a sense of scale the distance between the Kinglake (k) and Marysville (M) on the map is about 50 km. Locations are approximate)

The fires (hotspots) as detected on IR are marked with red outlines. The pink colour inside represents open flame in this instance. These areas are relatively large, indicative of the intensity and size of the fires.

Quite extensive smoke plumes are also apparent, extending some 100s of km in some cases. The brighter white found inside the more diffuse grey of the smoke likely represents pyrocumulus, fire-induced clouds. (The true colour image from the same time is useful...)The smoke plumes from the fires were also visible on the BoM radars. The image below shows the radar returns from around the same time. The different fires are discernable by looking at the apparent source of the plume. Later in the day, the plumes returned much stronger echoes and became more continuous,

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