Community based wind erosion monitoring across Australia DustWatch Report Dust activity for January 2013 No: OEH 2013/0116

Figure 1. Mean Sea Level Pressure Analysis chart Dust Activity – 15 January 2013 Marcus Owen, our DustWatch volunteer in Newdegate / Lake Grace, Western Australia provided us with a great picture sequence of a rolling dust storm approaching silos near Lake Grace on 15 January 2013 (Photos 1a, b and c). This event registered at the Newdegate DustWatch Site as a moderate dust storm (visibility 200m to 1 km) (Figure 3). More of his great images are published on the Lake Grace Shires web page at: http://www.lakegrace.wa.gov.au/photos.html. The weather event causing the dust storm was a cold front (Figure 1) that resulted in local wind speeds in excess of 80 km/h. Thunderstorm activity associated with cyclone Narelle caused another spectacular dust storm in the four days earlier on 11 January 2013. This event did not register at any of the Western Australian DustWatch Sites but was reported to us by several DustWatchers and was widely covered in the media after spectacular images were posted on Weather Live (http://www.perthweatherlive.com). This reaffirms the fact that a combination of instrumented sites and interested community volunteers provides complementing information and in combination provides valuable NRM information. In both cases the combination of bare paddocks and very strong winds are to blame for the dust storms that, on 11 January, caused disruptions to air traffic (source: http://www.news.com.au) with significant cost to the Western Australian economy.

Photos 1a, b and c. Approaching dust storm near Lake Grace, WA. Photos Marcus Owen

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Dust Activity – Eastern Australia The Victorian Mallee NRM area, in particular to the south west of Euston remains the source of significant dust activity in south eastern Australia (Figure 3). Events overnight on 8 January 2013, 12 January and 31 January (Figure 2) originated in this area and were detected as far north as Bourke and as far east as Cowra (Figure 3). In all three cases a low pressure trough caused strong winds to pick up sediment from bare paddocks around Euston (Figure 4) leading to severe dust hazes on 8 and 12 January and to a severe dust storm on 31 January. The South Australian Minnipa DustWatch Site recorded one hour of moderate dust haze (visibility between 5 and 10km) on the back of strong southerly winds on 4 January 2013. The other low pressure systems later in January 2013 did not trigger any significant dust in Minnipa, indicating that the groundcover around the site is sufficient to prevent wind erosion for most wind speeds. This is substantiated by the cover maps (Figure 5) that Figure 2. Mean Sea Level Pressure Analysis chart show the area around Minnipa having above 50% cover. 31 January 2013

Figure 3. Hours of dust with visibility less than 10 km recorded at each DustWatch Node in January 2013

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Ground cover Figure 4. Ground cover around Walpeup and Euston for January 2013. There was only very little change in the overall cover across southern Australia. In the Rangelands additional fire scars continue to increase the area with less than 50% cover (red colours in Figure 5). In the New South Wales sheep/wheat belt there is a balanced mix of slight cover decrease due to crop harvest and a slight cover increase in irrigation areas and areas that benefitted from recent rainfall (Figure 6). The insert shows the area around the Walpeup and Euston DustWatch Sites, with an increasing number of cover values in the < 50% cover classes and therefore prone to wind erosion (red colours in Figure 4). Good cover conditions persist in the North Central NRM area in Victoria (Green colours in Figure 5). Not surprisingly the local DustWatch Site in Loddon Plains has not recorded any dust in January 2013. For technical details regarding the groundcover maps please see the factsheet ‘Ground cover monitoring for Australia’ (http://www.daff.gov.au/__data/assets/pdf_file/0006/2222088/daff‐ground‐cover‐monitoring‐for‐australia.pdf) Figure 5. Percentage ground cover for January 2013 as determined from MODIS data using the method of Guerschman et al (2009).

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Rainfall totals Rainfall deciles Rainfall almost repeated the pattern from last month with good falls of up to The good falls in western WA and eastern NSW are reflected in the 3 monthly 100mm in the southern half of Western Australia (Figure 6). Unfortunately, these deciles map (Figure 7). Most of WA is now above average rainfall. SA, VIC and falls did not extend into the inland parts of , NSW or Victoria, which most of NSW still remain in the below average to very much below average deciles received little or no rain in January 2013. The northern part of the New South class for the last 3 months. Wales wheat/Sheep belt received very good falls, particularly in the Moree / Gunnedah areas.

Figure 6. Rainfall totals for January 2013. Figure 7. Rainfall deciles for 1 November to 31 January 2013.

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MODIS satellite image Fires numbers through out New South Wales and winter farming region across Fires in southern Queensland were significant and similar to last month. There southern Australia as detected by the MODIS satellite were slightly up from was a large number for fires between the South Australian Strzelecki Regional December 2012 (Figure 8). Fire number and size in the rangelands of Western Reserve and the north western border of NSW. Australia were up from last month in line with the dryer conditions in the area.

Figure 8. Fires detected by MODIS satellite during January 2013 with colour markers indicating the week of detection.

The DustWatch Team Contact us at [email protected]

The MODIS image is courtesy of MODIS Rapid Response Project at NASA/GSFC, the fire data is courtesy of the Fire Information for Resource Management System (FIRMS) and the rainfall map is from the Australian . This project would not be possible without funding from: Caring for our Country; Lachlan, Lower Murray Darling, Murrumbidgee and Murray CMAs in NSW:; The Mallee CMA and North Central Catchment Management Authorities in Victoria; Department of Agriculture and Food WA, Wheatbelt Natural Resource Management in West Australia; and in-kind contributions from: Gwydir and Western CMAs in NSW; Eyre Peninsula and Murray Darling Basin NRMs in South Australian; and Griffith University in Queensland. We also gratefully acknowledge the contribution of DustWatchers who provide observations and help maintain the instruments.

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