Assoc Prof Steven Siems - Researcher Profile

Steven Siems

Address

School of Mathematical Sciences
Building 28, Clayton

Biography

The last Rainmaker

Associate Professor Steven Siems is examining the world’s first instance of significantly enhancing rain through the intentional dispersal of substances into the air, in a process known as ‘cloud seeding’.

“There have been many controversial results; there have been some unscrupulous, controversial scientists in the field, too. As a result, people tend to stay away from this field. However, down in Tasmania, cloud seeding has been going on and off on its own for almost forty years, and quite surprisingly, we found that they were getting some 5 to 11 per cent increase in rainfall per month.”

From examining satellite observations, Steven has helped determine that cloud seeding may be successful only in very specific areas – another of which might also be mainland Australia’s Snowy Mountains. If successful, a cloud seeding operation there will lead to greater water flow into the Murray-Darling Basin.

Cloud seeding has been something of a hit-and-miss affair, even for Steven.

“We’ve had a similar project up in Queensland. They wanted to do a flavour of cloud seeding three or four years ago when they were in the midst of a severe drought and water shortages. Scientifically it came out with limited results, but it’s been the basis for some really interesting studies. We now better understand the nature of the variability up there - how you can go from severe drought for years, then go to massive flooding.”

Steven is quick to point out that such manipulation of the hydrologic cycle is not uncommon. 

“As far as trying to divert a little bit of rainfall in select locations – I don’t see how that’s much different from irrigation in general. Changing a river to go here, pulling some water out there, trying to do that, ethically I find that comparable. Moreover, it’s not like your stealing water from there to put it up there. This is rain that was never going to fall.”

However, Steven is wary should we take such geoengineering too far. 

“Putting in aerosols into the stratosphere to combat climate change should only be used as a last resort. It’s so dangerous – we don’t know the repercussions, and we don’t understand what could happen when we start mucking with the climate on a global scale. I don’t mean to be alarmist, but there is the potential that we’re marching to a pretty grim, disruptive future. A four-degree increase in global temperatures – which might well be what we’ll see – is something that should really worry us. Still, the idea of changing the atmosphere like that scares me.”

Qualifications

PHILOSOPHY (APPLIED MATHEMATICS)
Institution: University of Washington
Year awarded: 1991
SCIENCE
Institution: University of Washington
Year awarded: 1987
SCIENCE
Institution: University of Missouri-Rolla
Year awarded: 1985

Publications

Book Chapters

Jimi, S., Gras, J.L., Siems, S.T., 2003, Nano-Particles at Cape Grim: A regional view using Southern Ocean Atmospheric Photochemistry Experiment (SOAPEX-2) as a case study, in Baseline Atmospheric Program Australia 1999-2000, eds N W Tindale, N Derek and P J Fraser, Bureau of Meteorology and CSIRO Atmospheric Research, Melbourne Vic Australia, pp. 54-60.

Cox, M.J.D., Siems, S.T., Fraser, P., Hurley, P., Sturrock, G., 2003, TAPM modelling studies of AGAGE dichloromethane observations at Cape Grim, in Baseline Atmospheric Program Australia 1999-2000, eds N W Tindale, N Derek and P J Fraser, Bureau of Meteorology and CSIRO Atmospheric Research, Melbourne Vic Australia, pp. 25-30.

Journal Articles

Huang, Y., Siems, S.T., Manton, M.J., Protat, A., Delanoe, J., 2012, A study on the low-altitude clouds over the Southern Ocean using the DARDAR-MASK, Journal of Geophysical Research [P], vol 117, issue 17, American Geophysical Union, Washington DC USA, pp. 1-15.

Hande, L., Siems, S.T., Manton, M.J., Belusic, D., 2012, Observations of wind shear over the Southern Ocean, Journal of Geophysical Research [P], vol 117, American Geophysical Union, Washington DC USA, pp. 1-19.

Hande, L., Siems, S.T., Manton, M.J., 2012, Observed trends in wind speed over the Southern Ocean, Geophysical Research Letters [P], vol 39, American Geophysical Union, Washington DC USA, pp. 1-5.

Tessendorf, S.A., Bruintjes, R.T., Weeks, C., Wilson, J., Knight, C.A., Roberts, R.D., Peter, J.R., Collis, S., Buseck, P.R., Freney, E., Dixon, M., Pocernich, M., Ikeda, K., Axisa, D., Nelson, E., May, P., Richter, H., Piketh, S., Burger, R.P., Wilson, L., Siems, S.T., Manton, M.J., Stone, R., Pepler, A., Collins, D.R., Bringi, V.N., Thurai, M., Turner, L., McRae, D., 2012, The Queensland cloud seeding research program, Bulletin Of The American Meteorological Society [P], vol 93, issue 1, American Meteorological Society, Boston USA, pp. 75-90.

Huang, Y., Siems, S.T., Manton, M.J., Hande, L., 2012, The structure of low-altitude clouds over the Southern Ocean as seen by CloudSat, Journal Of Climate [P], vol 25, issue 7, American Meteorological Society, Boston MA USA, pp. 2535-2546.

Morrison, A., Siems, S., Manton, M., 2011, A three-year climatology of cloud-top phase over the Southern Ocean and North Pacific, Journal Of Climate [P], vol 24, issue 9, American Meteorological Society, USA, pp. 2405-2418.

Chubb, T., Siems, S., Manton, M., 2011, On the decline of wintertime precipitation in the Snowy Mountains of southeastern Australia, Journal Of Hydrometeorology [P], vol 12, issue 6, American Meteorological Society, USA, pp. 1483-1497.

Morrison, A.E., Siems, S.T., Manton, M.J., Nazarov, A., 2010, A modeling case study of mixed-phase clouds over the Southern Ocean and Tasmania, Monthly Weather Review [P], vol 138, American Meteorological Society, Boston USA, pp. 839-862.

Peter, J.R., Siems, S.T., Jensen, J.B., Gras, J.L., Ishizaka, Y., Hacker, J.M., 2010, Airborne observations of the effect of a cold front on the aerosol particle size distribution and new particle formation, Quarterly Journal Of The Royal Meteorological Society [P], vol 136, issue 649, John Wiley and Sons Ltd, Sussex England, pp. 944-961.

Jinsart, W., sripraparkorn, C., Siems, S., Hurley, P., Thepanondh, S., 2010, Application of the air pollution model (TAPM) to the urban airshed of Bangkok, Thailand, International Journal of Environment and Pollution [P], vol 42, issue 1-3, Inderscience Enterprises Ltd, Geneva Switzerland, pp. 68-84.

Wapler, K., Lane, T.P., May, P.T., Jakob, C., Manton, M.J., Siems, S.T., 2010, Cloud-system-resolving model simulations of tropical cloud systems observed during the tropical warm pool-international cloud experiment, Monthly Weather Review [P], vol 138, issue 1, American Meteorological Society, Boston USA, pp. 55-73.

Caine, S., Jakob, C., Siems, S.T., May, P., 2009, Objective classification of precipitating convective regimes using a weather radar in Darwin, Australia, Monthly Weather Review [E], vol 137, American Meteorological Society, Boston USA, pp. 1585-1600.

Morrison, A.E., Siems, S.T., Manton, M.J., Nazarov, A., 2009, On the analysis of a cloud seeding dataset over Tasmania, Journal of Applied Meteorology and Climatology [P], vol 48, issue 6, American Meteorological Society, Boston USA, pp. 1267-1280.

Gras, J.L., Jimi, S.I., Siems, S.T., Krummel, P.B., 2009, Postfrontal nanoparticles at Cape Grim: Observations, Environmental Chemistry [P], vol 6, issue 6, CSIRO Publishing, Melbourne VIC Australia, pp. 508-514.

Jimi, S.I., Siems, S.T., McGregor, J.L., Gras, J.L., Katzfey, J., 2008, An investigation into the origin of aerosol nucleation events observed in the Southern Ocean boundary layer, Australian Meteorological Magazine, vol 57, issue 2, Australian Bureau of Meteorology, Melbourne VIC Australia, pp. 85-93.

Jimi, S.I., Gras, J.L., Siems, S.T., Krummel, P., 2007, A short climatology of nanoparticles at the Cape Grim Baseline Air Pollution Station, Tasmania, Environmental Chemistry, vol 4, CSIRO Publishing, Melbourne Vic Australia, pp. 301-309.

Peter, J.R., Siems, S.T., Jensen, J.B., Gras, J.L., Ishizaka, Y., Hacker, J.M., 2006, Prediction and observation of cloud processing of the aerosol size distribution by a band of cumulus, Quarterly Journal of The Royal Meteorological Society, vol 132, issue 616, Royal Meteorological Society, Reading England, pp. 845-863.

Cox, M.L., Sturrock, G., Fraser, P.J., Siems, S.T., Krummel, P., 2005, Identification of regional sources of methyl bromide and methyl iodide from AGAGE observations at Cape Grim, Tasmania, Journal of Atmospheric Chemistry, vol 50, issue 1, Springer, Dordrecht Netherland, pp. 59-77.

McGibbony, S.C., Siems, S.T., Physick, W., Hurley, P., 2005, The sensitivity of simulations of air pollution events at Cape Grim to the modelled meteorology, Australian Meteorological Magazine, vol 54, issue 4, Australian Bureau of Meteorology, Melbourne Vic Australia, pp. 321-331.

Cox, M.J.D., Fraser, P., Sturrock, G., Siems, S.T., Porter, L.W., 2004, Terrestrial sources and sinks of halomethanes near Cape Grim, Tasmania, Atmospheric Environment, vol 38, issue 23, Pergamon-Elsevier Science Ltd, Oxford UK, pp. 3839-3852.

Cox, M.L., Sturrock, G., Fraser, P., Siems, S.T., Krummel, P., O'Doherty, S., 2003, Regional sources of methyl chloride, chloroform and dichloromethane identified from AGAGE observations at Cape Grim, Tasmania, 1998-2000, Journal of Atmospheric Chemistry, vol 45, issue 1, Kluwer Academic Publishers, Dordrecht Netherland, pp. 79-99.

Jimi, S., Gras, J.L., Siems, S.T., 2002, Nano particles at Cape Grim: A regional view using SOAPEX case study, Baseline Atmospheric Program, Commonwealth of Australia, Melbourne Vic Australia.

Siems, S.T., Hess, G.D., Suhre, K., Businger, S., Draxler, R.R., 2000, The impact of wind shear on observed and simulated trajectories during the ACE-1 Lagrangian experiments, Australian Meteorological Magazine, vol 49, Aust Govt Publishing Service, Canberra ACT Australia, pp. 109-120.

Wang, Q., Suhre, Krummel, P., Siems, S.T., Pan, M., Bates, T.S., Johnson, W.M., Lenschow, D.H., Heubert, Kok, Schillowski, Prevot, Businger, 1999, Characteristics of the marine Boundary Layer observed during Lagrangian measurements. Part 1: general conditions and mean characteristics, Journal of Geophysical Research - Oceans, vol 104, American Geophysical Union, www.agu.org, pp. 21751-21766.

Lenschow, D.H., Krummel, P., Siems, S.T., 1999, Measuring Entrainment, Divergence and Vorticity on the Mesoscale from Aircraft, Journal of Atmospheric and Oceanic Technology, vol 16, American Met. Soc., www.ametsoc.org/AMS/, pp. 1384-1400.

Businger, Johnson, R.K., Katzfcy, J., Siems, S.T., Wang, Q., 1999, Smart tetroons for Lagrangian air-mass tracking during ACE-1, Journal of Geophysical Research - Oceans, vol 104 issue d9, American Geophysical Society, www.agu.org, pp. 11709-11722.

Russell, L.M., Lenschow, D.H., Laursen, K.K., Krummel, P.B., Siems, S.T., Bandy, A.R., Thornton, D.C., Bates, T.S., 1998, Bidirectional mixing in an ACE-1 marine boundary layer overlain by a second turbulent layer, Journal of Geophysical Research, vol 103 no d13, American Geophysical Union, www.agu.org, pp. 16411-16432.

Siems, S.T., 1998, Climates & Weather Explained, Australian Meteorological Magazine, vol 47 no 3, Australian Bureau of Meteorology, www.bom.gov.au, pp. 270-271.

Whittlestone, S., Gras, J.L., Siems, S.T., 1998, Surface air mass origin during the First Aerosol Characterization Experiment (ACE 1), Journal of Geophysical Research, vol 103 no d13, American Geophysical Union, www.agu.org, pp. 16341-16350.

Boers, R., Krummel, P.B., Siems, S.T., Hess, G.D., 1998, Thermodynamic structure and entrainment of stratocumulus over the Southern Ocean, Journal of Geophysical Research, vol 103 no d13, American Geophysical Union, www.agu.org, pp. 16637-16650.

Conference Proceedings

Cox, M.J. ., Fraser, P., Sturrock, G., Siems, S.T., 1999, Regional and Background Measurements of Halomethanes at Cape Grim, IUGG 99 Birmingham Abstracts, Birmingham UK 19-24 July 1999, IUGG, Birmingham UK, p. A109.

Other

Krummel, P., Boers, R., Siems, S.T., 1997, Microphysical and thermodynamic structure of the stratocumulus capped boundary layer during the Southern Ocean Cloud experiment, 1997 Joint Assemblies of IAMAS & IAPSO, Local Organising Committee 1997 IAMAS & IAPSO, Australia.

Jensen, J.B., Siems, S.T., Larsen, H., Wratt, D., Bradley, S., Werkhoven, C.J., Lee, S., 1997, SALPEX 1996: observations of a frontal system on the windward and lee side of the South Island, 1997 Joint Assemblies IAMAS & IAPSO, Local Organising Committee 1997 IAMAS & IAPSO, Australia.

Wratt, D., Austin, G., Bradley, S., Henderson, R., Jensen, J.B., Lane, A., Larsen, H., Seed, A., Siems, S.T., Tilford, K., 1997, SALPEX '96 - orographic influences on clouds and precipitation, 1997 Joint Assemblies IAMAS & IAPSO, Local Organising Committee IAMAS & IAPSO, Australia.

Postgraduate Research Supervisions

Current Supervision

Program of Study:
(MASTER'S BY RESEARCH).
Thesis Title:
Climatology.
Supervisors:
Siems, S (Main).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
Mid-level clouds in the Southern Ocean and their representation in climate models.
Supervisors:
Jakob, C (Main), Siems, S (Joint).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
Observation and simulation of cloud thermodynamic phase over the Southern Ocean.
Supervisors:
Siems, S (Main), Manton, M (Associate).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
Observations and microphysics of super cooled liquid water over the snowy mountains..
Supervisors:
Siems, S (Main), Manton, M (Associate).
Program of Study:
(MASTER'S BY RESEARCH).
Thesis Title:
On Determining Cloud-top Height Using Satellite Measurements.
Supervisors:
Siems, S (Main), Ramsay, H (Associate).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
Rainfall and trade winds along the coast of eastern Queensland.
Supervisors:
Siems, S (Main), Manton, M (Associate).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
The Relation between the Precipitation over the Great Dividing Range and the Clouds over the Souther.
Supervisors:
Siems, S (Main), Belusic, D (Associate).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
The atmospheric boundary layer over the Southern Ocean.
Supervisors:
Manton, M (Joint), Siems, S (Joint-co).
Program of Study:
(DOCTORATE BY RESEARCH).
Thesis Title:
The dynamics of gravity wave emission from upper jets and extratropical cyclones..
Supervisors:
Reeder, M (Main), Siems, S (Associate).

Completed Supervision

Student:
Bisignanesi, V.
Program of Study:
Scalar plumes in canopies and atmospheric surface layers. (PHD) 2006.
Supervisors:
Siems, S (Main).
Student:
Caine, S.
Program of Study:
The classification and simulation of precipitating convective regimes over Darwin, Australia. (PHD) 2009.
Supervisors:
Siems, S (Main).
Student:
Chubb, T.
Program of Study:
On the nature of wintertime precipitation in the Alpine regions of South-Eastern Australia. (PHD) 2011.
Supervisors:
Siems, S (Main), Manton, M (Associate).
Student:
Clarke, A.
Program of Study:
Meteorology. 2003.
Supervisors:
Siems, S (Main).
Student:
Cox, M.
Program of Study:
A REGIONAL STUDY OF THE NATURAL SOURCES AND SINKS OF THE MAJOR HALOMETHANES. (PHD) 2001.
Supervisors:
Siems, S (Main).
Student:
Draper, C.
Program of Study:
The atmospheric water balance over the Murray-Darling Basin.. (Masters) 2006.
Supervisors:
Siems, S (Main).
Student:
Henbest, S.
Program of Study:
Numerical Investigation into cloud seeding potential and practices over Tasmania and the sensitivity of rainfall prediction in TAPM v3. (Masters) 2005.
Supervisors:
Siems, S (Main), Reeder ((Double Id)), M (Associate).
Student:
Jimi, S.
Program of Study:
NANOPARTICLES IN THE MARINE BOUNDARY LAYER: A REGIONAL PERSPECTIVE USING IN SITU OBSERVATIONS AT CAPE GRIM, TASMANIA-AUSTRALIA. (PHD) 2004.
Supervisors:
Siems, S (Main).
Student:
Lane, T.
Program of Study:
THE GENERATION OF ATMOSPHERIC GRAVITY WAVES BY OROGRAPHY AND CONVECTION. (PHD) 2000.
Supervisors:
Reeder, M (Main), Siems, S (Associate).
Student:
Morrison, A.
Program of Study:
Cloud seeding over Tasmania: a long-term evaluation and modelling plausibility study. (PHD) 2009.
Supervisors:
Siems, S (Main), Siems, S (Main), Reeder, M (Associate), Manton, M (Associate).
Student:
Mtilatila, L.
Program of Study:
Seasonal prediction of summer rainfall in southern Africa. (Masters) 2010.
Supervisors:
Jakob, C (Main), Siems, S (Associate).
Student:
Nguyen, L.
Program of Study:
Simulation of Winter Monsoon Season over East Asia using CCAM. (Masters) 2007.
Supervisors:
Siems, S (Main), Clarke, S (Associate).
Student:
Nguyen, T.
Program of Study:
FORECASTING TROPICAL CYCLONE MOTION NEAR VIETNAM USING A NESTED SHALLOW WATER BAROTROPIC MODEL. (Masters) 2000.
Supervisors:
Reeder, M (Main), Siems, S (Associate).
Student:
Peter, J.
Program of Study:
Aerosol processing by a cumulus band and a cold front. (PHD) 2006.
Supervisors:
Siems, S (Main).
Student:
Spackman, S.
Program of Study:
Frontal passages. 2008.
Supervisors:
Wardle, R (Main), Siems, S (Associate).
Student:
Williams, M.
Program of Study:
A diagnosis of the tropical global circulation from the perspective of four planetary waves driven by multiple heat sources. (PHD) 2007.
Supervisors:
Mcbride, J (Main), Siems, S (Associate).