Gedday,

 there is an article on a website named ninemsn.com.au about a mammoth dust storm apparently sweeping across western New South Wales and Western and central Queensland.  The website is a stinker in terms of being a heavy consumer of ram etc and has brought down both of my computers; so I can't capture the text.  However it quotes Greg Bond as saying it is the most massive storm he has seen in his 30 years on the Bench.

Other than the obvious comment that it is a shame this forum wasn't used to alert the rest of us... can someone capture the relevant satellite images, maps of observations of where the dust is relevant to synoptic features, etc.  If it is boob-Melbourne dust-storm in nature and has all the dust confined to the cold air, a few photographs would be good too.

cheers
John Mcb

Matt Wheeler
 Wed, 23 Oct 2002 17:13:05 +1000 (AEST)
John,
I just got an e-mail from a mate in Brisbane about it, so it must
have reached there.
-Matt.

Robin Bowen/Press Releases
hi John

the Bureau has a couple of press releases out see
http://www.bom.gov.au/announcements/media_releases/nsw/20021023.shtml
for Sydney and
http://www.bom.gov.au/announcements/media_releases/qld/20021023.shtml
for Queensland
however response is very slow as our server is being hit hard !

Saved Copies of Press releases:
   Dust storm envelops Sydney
   Dust storm sweeps across Queensland interior
   Dust storm continues to sweep across Queensland
   Dust storm moves over the eastern tropics

Gordon Jackson
    John
It can be seen on Qld's web site at
         http://serva.qld.bom.gov.au/~mcuser/images/index.html
    Stored copy: jtd5.gif
latest GMS is attached with comma shaped head now approaching SE Qld.

Gordon

GMS IR_Images for that day:
Australia: 22nd Oct: 1700    2300 UTC
                23rd Oct    0000   0300 UTC

Queensland:  22 Oct.     09    11  17    23
                    23 Oct        00   03    06

John McBride
Are there any maptool loops or images for Qld and or NSW up on the web anywhere (like you can get for Vic from the VRO weather browser)?  From the GMS images it looks like the dust cloud is in the cold air behind the front; but it would be nice to see some observations confirming this?

John McB

Helen Pearce:
These are dust imageries this mornning: (Produced by Lee Hong, Satellite Section)
 1.  GMS-5 22 Oct 2002 22:25 UTC  vis+ir1.........dust02295-22z.jpg

 2.  FY1D   22 Oct 2002 21:58 UTC RGB=ch6:ch2:ch7
.....dust02295fy1-ch627-22z.jpg

Claire Yeo
Date: Wed, 23 Oct 2002 20:07:45 +1000

hello young generation X met bleap here,

We had been quite run off our feet up here in QLD - even Oakey Met - I had a TV interview,
3 radio, newspapers, as well as the warnings for aviation etc - so you may appreciate
the lack of time for all operational mets and alike.  All in all, glad to experienced such
a event - at the forefront on the bench!

After the trough moved through Oakey at 0445ish Z , the dewpoint went from  +3 to -15,
but temperature remained the same.  Ahead of the change we had gusts up to 43 knots.
Claire

John McBride
Dear young gen-Xy person,

 Thanks for this... You in Brisbane may have had low visibility, but we in HeadOffice are completely in the dark... at least as far as knowing what went on is concerned.

Would it be possible for you to write a paragraph or two describing the synoptics, where was the dust as related to synoptic features, evolution through the day, etc.

 Also, could someone on some timescale take the relevant Qld and NSW regional scale charts, circle the dust area and scan them for us all to see...

 Gotta rush...down to NMOC chart discussion to see if anyone knows anything about dust (other than of the bull... variety)
I know this is bad for farmers... but I still thrill at how the atmosphere keeps throwing up new and interesting events at us

John McB

Blair Trewin
Also, further down the track, I think we'd be very interested in seeing an
article (brief or otherwise) for the AMOS Bulletin (or the Met. Mag, or a
Met. Note, but these tend not to appear for months or years respectively).

Blair

Claire Yeo
John,

The wind change and drop in dewpoint occured about 40-70 minutes before the main duststorm hit
- i.e visibilty only became reduced to below 5000M after the change in dewpoint and wind.
The actual observations in this time period  in Oakey which is 150km due west of Brisbane were:

0400 Z      310 28G36KT  T=35.2, Tp=0.7  Qnh=997.6 (about 996.6 MSLP)  blowing dust only in the gusts

0505  290 27G38KT   T=35.5  Tp= -14.4  p=995.4   blowing dust only in gusts

0524  28030G42KT   T=35.2   Tp=-15.5   p=995.6   Actual duststorm arriving vis reducing to 7km to west

0543  27030G41KT   T=34.0   Tp=-15.6   p=995.8  Duststorm uniform Vis = 5km

0600  260 30G38KT   T=33.5   Tp= -13.3   p=996.0  Duststorm  uniform vis= 4km

0610  26027G38KT    T=32.4   Tp=  -10.8    p=996.2    Uniform Vis=1000M

0700   24024G30KT    T=30.0   Tp=  -4.8  p=997.1   Uniform vis = 800M

0755 mostly as above,   p=998.5

0900   25021G29KT  T=25.3    Tp= -4  p=1000.1   Vis improved to above 6km.

On the vis sat pic I noticed that the high based Cu field developed on a sharp line just ahead
of the duststorm line which varifies the wind change occuring ahead of the actual duststorm.
Hope this is useful.
Claire Yeo.

Jason Davey
G'day all.

The MODIS images are worth a look at for the dust storm
http://rapidfire.sci.gsfc.nasa.gov/
then go to real-time products, ie,
http://rapidfire.sci.gsfc.nasa.gov/production/

The 00:45 UTC Terra/MODIS image from the 23rd shows the dust over Qld  really well (copy here), and you can also see it on the 00:50 UTC image over NSW [copy here] (a bit squished as it is at the edge of the image).  These images tend to take
about 7-8 hours to become available.

Regards, Jason.

Jon Gill
 there is a nice MODIS image of it off the east coast, at the MODIS image of the day web site at

http://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2002-10-28

Click on the link in the right panel to view your chosen resolution (down to 250m. 4.7MB file though). (1 km resolution copy here) You can notice some interesting things apart from the dust. e.g: a bulging 'head' of the front/wind change appears to be delineated as a line of Cu behind the trailing edge of the dust plume (at a latitude a little north of Brisbane)

Need less to say, it would be great to get the MODIS stuff in the BoM realtime.

Cheers...Jon
 

Ashley Patterson

There is an interesting cloud structure over the Top End this morning - see vis pic. There appears to have been  a low level surge/pulse into the Top  End related to the trough that moved across Qld and north to the base of  the Top End. However we still have sfc westerlies across the Top End.
Darwin's wind profile below 850hPa shows a change from NW to SW in the past 2 hrs to 2230Z.
Any comments?

Later:
John,

Please find attached the two vis pix from this morning. This is all we received due to the reduced operations of GMS.
TOPVIS00Z.gif           TOPVIS23Z.gif

Peter May

John, Ashley,

I don't know about something intelligent, but the real wavy stuff looks
like one of Roger Smith's southerly morning glories and there is the really
sharp line in amongst th emess near Cape Don that is probably related to
the same forcing - the southerly puch inteacting with the nocturnal inversion?

Peter

Harald Richter
After being prompted I guess I could chime in.  Having looked at 23Z and 00Z VIS imagery a number of organised cloud bands appeared over the top end,   reminiscent of the Morning Glory in the S Gulf of Carpentaria.  During  GELX2002 I developed a hunch that waves travelling within/on stably stratified layers of air in the atmosphere are salient features, but that we only see very few of them as the pressure perturbations associated with those waves are relatively small.
This means _relative_ humidity would play a major role in us seeing those waves.  The 23Z Darwin sounding shows about ~80mb of very rich moisture (~17 g/kg equating to a surface dewpoint of 22-23 C.  Relative humidity at the top of that layer is ~100%;  above that we have stably stratified air.
This is how I try and make sense of it....

Harald

PS:  I like the CAPE in the 23Z Darwin sounding...
 
 

John James

For interest, most aircraft reports over NSW that I have seen, mention the dust to about 10000ft. RAAF reported some dust to at least 20000/23000ft just to the west of Sydney, naturally much thicker closer to the surface.
regards

John James
Williamtown Met Office

Lee Hong
Hi all,

The following two images are:
1. FY1D 23 OCT 2002 21:49 UTC RGB=ch6:ch2:ch7 .......
                          dust02296fy1-ch627-22z.jpg
2. NOAA-16 23 OCT 2002 03:34 UTC RGB=ch6:ch1:ch4.......
                          dust02296n16-3z.jpg
Regards,

Lee Hong
Satellite Section

John McBride

Hmm... so the question is.. what causes a dust-storm like this?  Clearly the drought is part of it, bringing us below some soil-moisture (whatever that means) threshold, low vegetation cover so the soil is not held together etc.  That is the longer-time scale context.  On the shorter term presumably we need something other than strong winds... often the
stronger winds are in the northerlies ahead of the change, whereas the (contained) dust is in the westerlies or southerlies behind the change...so there has to be some mechanism of containment to keep it all together in a coherent storm.

I guess before speculating too much we should wait and see some of the observations.  Going by the analogue of the 1983 event one of the key features of that front was it was rapidly moving so  there were very large pressure falls ahead of it, and large ones behind and  the single station barograph looked like a tropical storm had gone over... what were the pressure tendencies like in this case?  In terms of what was unusual about the front (to give a one in 40-something years event) it may be the fact the southerly change extended so far north/inland???  I don't know... I would need to look at a cliamtology of fronts.

Another lesson from 83 was that the next front that came along a week later (the ash Wednesday fires event)  also included a frontal dust-smoke cloud that was not actually observed by the media as it came in at night. The next front (third in the series)  also had one; but it was thinner and the front broke up before it reached  Melbourne.  Before the fourth  front came through we had the monsoon depression El-Nino busting rains and the drought was over..... So....  there could be another dust storm with next friday's front?

cheers
John McB

Robin Hicks
John,

It may be of note that most places from Eastern Victoria as far as the northern inland of Qld achieved record low MSL pressures for October, or at least the observations for almost a day were failing the bounds check in QMS, indicating that the observed pressure was below the previous "extreme" value set in QMS for October. For example, Mallacoota (Vic) got down to 984 hPa, locations around Sydney of the order of 989hPa, the Gold Coast 993hPa, Rolleston (Qld), 997hPa.

As I recall the 1982 - 83 summer season (my last summer as a forecaster), one thing in common has been the highly baroclinic systems that have crossed SE Australia, together with the perception that they are occurring later into spring and summer than usual. Normally, by late October, Victoria would be expecting changes produced by easterly troughs that are often associated with only moderate winds either side of the change line, and humid weather with thunderstorms. In contrast the Melbourne Dust Storm of 8 Feb 1983 and Ash Wednesday were examples of these intense troughs, with dry air both
ahead and behind the change. On Ash Wednesday the situation was slightly different, as I remember about 8am on the day hurriedly amending southern Victorian TAFORS for thunderstorms that rapidly formed ahead of the trough before being blown to bits in the middle layers by the strengthening mid -level winds I recently drove across through Mildura to the Flinders ranges. Perhaps with so little ground vegetation evident, not only is there more loose soil available for lifting, but the albedo is increased leading to stronger surface heating. This would result locally in deeper layers of dry unstable air near the surface but also a stronger thermal gradient between the inland and the cooler southern ocean.

Robin Hicks
SRDM
National Climate Centre

John McBride

Consistent with Robin's observations, I have put up on my web-page the large scale analyses from the NOAA CDC
site of surface wind anomaly, surface temperature anomaly and surface pressure anomaly for the 23rd.  The surface pressure anomaly is particularly impressive.

John McB

Andrew Treloar
Robin,

I believe that Sydney's lowest pressure was 987.2hPa - that's the third lowest on record since 1951.

Cheers,
Andrew

Jenny Dickins
>From South Australia's perspective, Tuesday's dust storm (it was a Tuesday event over here!) was the third in a week. So ... if John's 1983 analogy is a goer, we can look forward to drought busting rains within a week or so.
You beauty!

The first event (Wednesday 16 October) occurred with a front which was initially fairly weak, but intensified north and east of Adelaide and generated gale force winds and blinding dust through the Riverland and adjacent pastoral districts north to at least Broken Hill (and probably into NW Victoria and western NSW).

The second was last Friday (18 October), when we had an Ash Wednesday type day (but thankfully in October, instead of February). A front associated with a confluent trough hurtled across SA at almost 60 knots. Again severe dust with the front everywhere north and east of Adelaide. Huge isallobars (8 hPa/3 hours) to the west and southeast of the front contributed to the severe winds that accompanied this system.
And the third in the series was last Tuesday (22 October), which has already been discussed. In SA, the post frontal winds were gale force north of about Elliston - Cleve - Renmark, with the most severe conditions right across the pastoral districts from late afternoon onwards. Many places experienced 3-4 hours of sustained 33-38 knot southwest winds and thick
dust (horrible). The dust is just discernible on the 0830 UTC visible satellite image (but sun is getting very low).

Our local progs performed very poorly during the first event, but were truly superb with the second event and apart from the spurious rain, were excellent value also for this last event.

regards
Jenny

Dust References:

1.   I found a good reference.  JGR Atmosphere, available as a pdf file online via the Library on the Bureau's internal home page.  In the section on "Dust sources and uplift" it contains various references on papers describing models, algorithms and atmospheric conditions  for uplift of dust:

1. Tegen and Fung, JGR atmospheres 1994, Vol 99 D11 p. 22897ff, Modelling of mineral dust in the atmosphere: sources, transport and optical thickness

2. Tegen and Fung, 1995< JGR Atmospheres Vol 100, p. 18707ff: Contribution to the atmospheric aerosol load from land surface modification.
cheers
John McB

2.     ........ and of course there is the classical text: "The physics of blown sand
and desert dunes, R. A. Bagnold, Methuan and Co., 1941.

I just now raced up and borrowed it from the Bureau library.  I'll skim through it over the next few days so that I can pass it on to any other borrowers by about Monday.

3.  John,

There is Bagnold's book:  The Physics of Blown Sand and Desert Dunes.
In HYSPLIT we use an algorithm based on:
Westphal, Toon & Carlson, 1987, JGR, 92, 3027-3049

   In AAQFS we use an algorithm based on:
Lu  H. and Shao Y. 1999, ^ÑA new model for dust emission by saltation  bombardment^Ò, J. Geophys. Res, 104:16827-42.
Lu  H. and Shao Y. 2001, ^ÑToward quantitative prediction of dust storms:     an integrated wind erosion modelling system and its applications^Ò,     Env. Modelling & Software, 16:233-49.

       Dale

4.
Hi John

rereading my masters thesis I note a dust storm in Dec 1987 which affected 65% of Queensland and about 6 million tonnes of soil! Followed a very similar path.

Other references FYI

K Pye 1987 Aeolian Dust and Dust Deposits
McTainsh & Boughton (eds) 1993  Land Degradation Processes in Australia

Cheers
Alan