Geoscience Reference
In-Depth Information
extended above 850 hPa and in some cases above 700 hPa. In the climatol-
ogy, 900 hPa wind speeds at 0000 UTC (08:30 local time) at Woomera, the
station nearest the source area, were all greater than 30 knots for long-range
dust transport associated with fronts that cleared the east Australian coast
and greater than 20 knots for dust transport associated with fronts that
stalled or weakened over eastern Australia. However, there was no threshold
value of the 900 hPa wind speed that discriminated between these frontal
characteristics within the long-range category.
3. Brief Overview of Case Studies
3.1.
Case study 1: October 23, 2002
The main antecedent conditions for dust storm generation are drought or
rainfall deficiency over the dust source region, as for the Lake Eyre (SA)
drainage basin for the 6 months ending September 2002, when rainfall defi-
ciencies were the lowest on record. During such periods of rainfall deficiency,
the surface soil is far more prone to wind erosion than usual.
3.2.
Case study 2: February 2, 2005
In the 6 months to the end of January 2005 there were rainfall deficiencies
below decile 3 (very much below average) in the Lake Eyre source region and
this area of very much below average rainfall increased in the three months
ending January 2005 over the source region. With a vigorous frontal system
developing in the GAB, dust storm generation in northeast SA is likely to
occur.
4. Integrated Wind Erosion Model
4.1.
The atmospheric model
The atmospheric model used is the HIgh RESolution NWP model (HIRES),
developed at The University of New South Wales and the University of
Oklahoma.
7
Model features are in Table 2.
4.2.
The wind erosion scheme
Details of the wind erosion scheme were described originally by Shao
et al.
,
3
and since then improvements have since been made to the land surface
scheme, the GIS database, and the particle entrainment, transport and
