Seminars - Melbourne
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CAWCR SEMINARS 2014
The venue is the seminar room (Floor 9, east side) at 700 Collins Street, Docklands
Seminars are run typically with duration
of 30 to 45 minutes + questions. Dates and times are shown. If you are a vistor to the Bureau, you need to register at reception in the foyer.
For further details contact the
Wednesday 21sy May, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
On the rates of record setting in Australian monthly and seasonal temperature time series
Abstract: We describe the rates of new record setting over time for monthly, seasonal and annual temperature anomalies across Australia, using monthly temperature anomaly analyses of the Bureau of Meteorology's ACORN-SAT dataset, nationally and regionally averaged for the period 1910-2013. The site temperature data feeding into the analyses have been subjected to stringent quality control and homogeneity assessments. A new high record is deemed to have been set in our time series when the current value exceeds all the previous values, with new low records being defined analogously. By definition the first value of the time series represents a new record. This study is particularly focussed on how frequently such new records, both high and low, are set. We find that new high records are occuring at much higher rates than new low records, and in some cases new low records have become very scarce. In some parts of the country, there has been a burst of new high records in recent years, consistent with a warming climate.
Wednesday 7th May, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
c/o Gary Brassington
Wednesday 30th April, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Google Scholar: track your citations and search for papers
Google Scholar is not only a valuable tool for finding others publications. It can also be used to keep track of your own publications and citations of them. This, in turn, can be used to assist in gathering information for input into job applications and internal publication databases.
In this seminar, Matt Wheeler will introduce some of the features of Google Scholar, followed by a demonstration of how to create a Google Scholar profile and link your existing publications to it. Having a profile enables Google Scholar to recommend papers to you, and making your profile accessible by the public increases your own exposure.
Friday 4th April, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Identifying East Coast Lows in reanalyses and models
BoM Climate Information Services / UNSW
East Coast Lows (ECLs) are strong low pressure systems that can cause severe weather and substantial rainfall along the east coast of Australia. Because of their importance, several databases of East Coast Lows have been developed in recent years, based on both manual identification of lows and objective tracking schemes that employ one or more reanalysis datasets.
In this talk I will discuss how sensitive the identification and characteristics of ECLs are to the choice of reanalysis dataset, spatial resolution of the pressure data, and the ECL identification method used. The ability of the WRF regional climate model to represent the seasonality and distribution of ECLs will also be briefly assessed, as well as its implications for future ECL studies as part of the NARCliM project.
Wednesday 2nd April, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
The Role of Soil Moisture and SSTs in Decadal Drought in Western North America
CIRES/ATOC, University of Colorado
Western North America is susceptible to severe impacts of decadal to multi-decadal droughts, as evidenced by treecore or lake sediment records. Future predictions suggest that this region will become more arid, with further consequences for water resources. Understanding the mechanisms of drought variability and persistence in western North America is critical for the eventual development of effective forecasting methods. The ocean is expected to be the main source of potential predictable decadal memory in the system as the atmosphere varies on a much shorter timescale. However, low frequency precipitation anomalies in western North America can occur in the absence of ocean feedbacks. Sea surface temperature anomalies in the north Pacific Ocean associated with around 20 per cent of the low frequency winter precipitation in California in the CMIP5 historical runs. This is not sufficient to use the skill of global coupled models in predicting ocean conditions ahead of time to successfully forecast the possibility of long-term drought in western North America. Megadroughts may be generated by unpredictable atmospheric noise, or persisted by other sources of low frequency variability such as land processes and feedbacks. Water storage and related variables which integrate precipitation are more predictable on longer timescales, as measured by anomaly correlation for hindcasts compared to a 'perfect model' control run with CESM1.0.3. The importance of SST anomalies or antecedent land conditions in initiating and persisting megadroughts in western North America is explored with ensemble simulations of CESM1.0.3, where the atmosphere is perturbed at the start and peak of megadroughts in the control run. The model results confirm the importance of internal variability, SST forcing and land processes in projections of future decadal hydroclimate; the relative role of each process differs for droughts with varying characteristics.
Friday 12th March, 10:00am - 11:00am, Conference/Meeting Rooms, 6th floor, 700 Collins St
Unified Model development: recent progress and future strategy
Director of Science, UK Met Office
Wednesday 12th March, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
An Assessment of Methods for Operational Mixing Height Determination; and the Southwest Monsoon and Fire Activity
Desert Research Institute, Nevada
Forecasts of mixed layer height are prepared for fire and smoke management such as prescribed burning, though smoke concentration and dispersion from wildfire is becoming increasingly important as related to public health. The nature of the primarily used Holzworth method and other mixed-layer determination techniques (e.g., Stull method) are principally based on the static stability structure of the atmosphere. However, their exclusion of the dynamic stability (e.g., wind shear) can lead to significant underestimation of the mixed-layer height. In the context of the operational forecasting, this study examines these techniques and compares computed heights to those derived from satellite-based lidar (from CALIPSO aerosol depth). Estimates are also examined against planetary boundary layer values from model-derived turbulent kinetic energy (TKE) the mean kinetic energy per unit mass associated with eddies in the turbulent flow, and a combined representation of static and dynamic stability. This presentation will describe these comparisons, and discuss a recommendation for a national standard methodology for operational mixing height determination in the U.S.
Friday 7th March, 2:00pm - 3:00pm, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Intraseasonal Predictability and Dynamical Processes: the MJO and NAO two-way global interaction
Deputy Director of Weather Science, UK Met Office
Wednesday 5th March, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
The Pilot National Heatwave Forecasting System
On 8 January 2014, the Bureau of Meteorology introduced a pilot national heatwave forecasting service. This seminar will describe the pilot forecasting service and the science behind it. While heatwave definitions have been used operationally in a small number of Australian locations (e.g., Adelaide), this new service represents the Bureau's first attempt at a national operational heatwave service. The service makes use of a concept called the Excess Heat Factor (EHF), developed by John Nairn in the Bureau's South Australian Regional Office. The EHF aims to capture the temperature signal relevant to human health outcomes. Future plans for the service and some preliminary verification results will be presented.
Friday 28th February, 2:00pm - 3:00pm, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Fast and slow response of sea ice and the Southern Ocean to ozone depletion
University of Washington
Interannual variability in the Southern Annular Mode (SAM) and sea ice covary such that an increase and southward shift in the surface westerlies coincides with an expansion of the sea ice cover, as seen in observations and models alike. Yet, the sea ice extent decreases in response to similar sustained wind anomalies driven by 20th century ozone depletion in modeling studies. Why does sea ice appear to have opposite responses to SAM-like variability on interannual and multi-decadal timescales? We demonstrate explicitly that the response of sea ice and the Southern Ocean to ozone depletion is a two timestep problem. The interannual variability of sea ice and the SAM parallels the fast response of sea ice to ozone depletion. The fast response is dominated by an enhanced northward Ekman drift, which transports heat northward and causes negative SST anomalies in summertime, earlier sea ice freeze-up, and increased sea ice concentrations and northward expansion of the sea ice edge year round. The enhanced northward Ekman drift causes a region of Ekman divergence south of the Antarctic polar front, which results in upwelling of warmer waters from below the mixed layer. With sustained westerly wind enhancement, the energy balance of the upper ocean is dominated by the upwelling heat flux from of the anomalous upwelling of warm waters over the northward heat flux from the anomalous Ekman drift. Hence, the slow response is positive SST in summertime and a reduction in the sea ice cover year round. We demonstrate this behavior in two models: one with an idealized geometry and another a sophisticated global climate model. We discuss the controls on the transitions of fast to slow response.
Wednesday 26th February, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Influence of Amplifying Rossby Waves on Tropical Cyclone Intensity, Structure and Rainfall
We re-visit the long-standing tropical cyclone-trough interaction problem and provide evidence that some storms experiencing significant changes in their behaviour, are influenced by direct interaction with amplifying, extratropical Rossby Waves. Back trajectories from the storm’s midlevels during these episodes, suggest that injection of environmental PV can influence vortex intensity, structure and rainfall. We illustrate the processes using case studies of: 1. Ex-TC Oswald, which produced extreme rain over Queensland, 2. Landfall of TC Fitow near Shanghai, where very heavy rain occurred 400km to the north of the centre, and 3. the much-studied Hurricane Opal, which underwent un-forecast and poorly-understood rapid intensification over the Gulf of Mexico just prior to landfall.
Monday 24th February, 11:00am - 12:15pm, Conference Room 3, 6th floor, 700 Collins St
UM status, plans & collaboration update
UK Met Office
This talk will cover Met office production; parallel suites from now to 2022; ENDGame; UM development and Rose; climate configs; global model evaluation and development; collaboration.
Friday 21st February, 12:00pm - 1:00pm, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Atmospheric dispersion and air quality research and services at the Met Office
UK Met Office
The Met Office deliver a range of dispersion and air quality services. In support of these, other policy questions and science challenges we conduct and collaborate in a wide ranging research program. This work focuses on developing and utilising the NAME (Offline Lagrangain model) and AQUM (Online configuration of the UM including suitable chemistry) models. During this talk I will describe the models and a number of the operational services and applications that they are applied to as well as the key role that collaboration plays in our success in both the services and research work. The talk will close with a brief look at our future plans and challenges.
Thursday 20th February, 2:30pm - 3:30pm, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Effects of declining aerosols in CMIP5 projections
All the Representative Concentration Pathways (RCPs) include declining aerosol emissions during the 21st century, but the effects of these declines on climate projections have had little attention. Whereas increasing aerosols have masked global warming in the past, projected declines in aerosol emissions are expected to accelerate global warming. However, the effects of declining aerosols on large-scale circulation may differ from those of increasing well-mixed greenhouse gases.
This talk will cover recent work that assesses the effects of declining anthropogenic aerosols in RCP4.5, and compares the effects with those of increasing well-mixed greenhouse gases. The analysis is partly based on “single-forcing” simulations with the CSIRO-Mk3.6 model, and is currently being extended to use a four-member multi-model ensemble. Topics to be addressed will include global and hemispheric changes in temperature and precipitation, midlatitude dynamics (including the southern annular mode) and the Hadley circulation.
Wednesday 19th February, 11:00am - 12:00pm, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Probabilistic prediction with deterministic models
University of Helsinki
Environmental management relies often on deterministic models and descriptions of the ecosystem to predict its response to management actions. However, from a practical management point of view the uncertainty in model predictions and the probability to achieve the targets are as essential as the point estimates provided by the deterministic models. In this talk I will present how to extend a deterministic model into a probabilistic form in order to assess the uncertainty in its predictions. As a case study I will consider a problem of predicting the probability to achieve the targets set by EU's Water Framework Directive (WFD) in Finnish coastal waters in the Gulf of Finland (GoF), one of the most eutrophicated areas of the Baltic Sea, under alternative management scenarios. Our approach combines the spatio‐temporal predictions of deterministic biogeochemical model with a Gaussian process to give a prior distribution for the spatio‐temporal function of nutrient concentrations and algal biomass. We use Bayes theorem and condition to large monitoring data set to calculate the posterior predictive distribution of the nutrient concentrations and algal biomass. This presentation will summarize the following work: Vanhatalo et al. (2013). Probabilistic Ecosystem Model for Predicting the Nutrient Concentrations in the Gulf of Finland under Diverse Management Actions. Environmental Science \& Technology, 47(1):334‐341.
Wednesday 19th February, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Representing tropical convection in weather and climate models - the need and opportunities for a revolution
ARC Centre of Excellence in Climate System Science, Monash University
The representation of convection in weather and climate models remains one of the most difficult tasks in contemporary model development. Many of the well-known model errors including the poor simulation of the tropical mean precipitation patterns as well as errors in the representation of major modes of tropical variability ranging from ENSO to the Madden-Julian Oscillation to the diurnal cycle of precipitation have been shown to be associated with flaws in the representation of convection. By necessity convection in climate models is represented by means of parametrization, which inherently relies on the exploitation of relationships between large and small scales in a convecting atmosphere.
Astonishingly, despite their clear shortcomings, contemporary parametrizations of convection still rely on paradigms developed in the 1970s and 1980s, including the existence of diagnostic and deterministic relationships between the "local" large-scale state of the atmosphere and the behaviour of an ensemble of convective clouds embedded in that state. We will exploit modern observations at Darwin, Northern Australia, to expose severe shortcomings in the decade-old paradigms currently in use. We will show that the common use of stability measures, such as CAPE, to determine the amount of convection in models is not supported by observations. We will demonstrate that much of the relationship between the large scales and convective rainfall is driven by the area that is precipitating. Finally we will apply our findings to the conceptual design of a new treatment of convection in large-scale models based on a prognostic and stochastic multi-scale cloud model.
Wednesday 12th February, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
The emerging IIOE-2, an exciting international scientific initiative five decades on from the original International Indian Ocean Expedition (IIOE) of the 1960s
A pioneering collaborative international scientific exercise to explore the Indian Ocean was undertaken under the auspices of SCOR and the IOC during 1959-65 - termed the International Indian Ocean Expedition (IIOE). It was a formative oceanographic program, including voyages of discovery, focusing the world’s ocean observing community on the Indian Ocean, uncovering scientific data of significant societal and environmental relevance, as well as catalysing the establishment of new marine institutions and forward interest in the ocean science of the basin.
The Indian Ocean and wider global oceanic community is planning now to revisit the Indian Ocean, in a major scientific undertaking, timed to coincide with the 50th anniversary of IIOE, again involving expeditions in the form of cruises but this time also with a range of significant complementary activities (see the IIOE-2 portal on www.iocperth.org).
The IIOE-2 planning phase is underway (2013-2014), co-chaired by IOC PPO and so far involving a suite of actions. Two IIOE-2 Reference Group meetings have taken place in 2013 (Hyderabad and Qingdao), including a team of international scientists, managers and officials. An IIOE-2 ‘science and implementation plan’ (incl. business case and budget) will be formulated and submitted to the IOC in mid-2014 to help motivate and underpin the planned implementation phase (2015-2020).
It is envisaged that IIOE-2 will comprise voyages of discovery, and encompass related scientific research, applications, training/capacity building, outreach and awareness themes and more. It will provide new information with relevancies to all Indian Ocean rim and island countries, as well as to the globe in general.
The seminar provides an opportunity for BoM stake-holders to (i) be briefed, (ii) identify linkages and (iii) consider engagement in this exciting IIOE-2 initiative.
Background IIOE and IIOE-2;
Reference Group meetings;
Towards an IIOE-2 science and implementation plan;
Plenary discussion - Australian stakeholder engagement and national approach to IIOE-2 engagement.
Wednesday 5th February, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Is there a causal link between moistening preceding deep convection and cumulus congestus clouds?
Monash University / CAWCR
Some cumulus clouds with tops between 3 and 7 km (Cu3km-7km) remain in this height region throughout their lifetime (congestus) while others develop into deeper clouds (cumulonimbus). Here we describe a technique to identify the congestus and cumulonimbus cloud types using data from scanning weather radar and identify the atmospheric conditions that regulate these two modes. A two-wet season cumulus cloud database of the Darwin C-band polarimetric radar is analysed and the two modes are identified by examining the 0 dBZ cloud top height (CTH) of the Cu3km-7km cells over a sequence of radar scans. It is found that ~26% of the classified Cu3km-7km population grow into cumulonimbus clouds. The cumulonimbus cells exhibit reflectivities, rain rates and drop sizes larger than the congestus cells. The occurrence frequency of cumulonimbus cells peak in the afternoon, at ~1500 local time, a few hours after the peak in congestus cells. The analysis of Darwin Airport radiosonde profiles associated with the two types of cells shows no noticeable difference in the thermal stability rates, but a significant difference in mid-tropospheric (510 km) relative humidity. We find moister conditions in the hours preceding the cumulonimbus cells when compared with the congestus cells. Using a moisture budget data set derived for the Darwin region, it is shown that the existence of cumulonimbus cells, and hence deep convection, is mainly determined by the presence of the mid-troposphere large-scale upward motion and not merely by the presence of congestus clouds prior to deep convection. This contradicts the thermodynamic viewpoint that the mid-troposphere moistening prior to deep convection is solely due to the preceding cumulus congestus cells.
Wednesday 22nd January, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Climate Impact of the Antarctic ozone hole: long-term trend and inter-annual variability
School of Earth and Environmental Sciences, Seoul National University
The impact of stratospheric ozone on the tropospheric general circulation of the
Southern Hemisphere (SH) is examined with observations, chemistry‐climate models participating in the Chemistry‐Climate Model Validation project phase 2 (CCMVal‐2), and coupled models from the Coupled Model Inter comparison Project phase 3 and 5 (CMIP3 and CMIP5). Model integrations of both the past and future climates reveal the crucial role of stratospheric ozone in driving SH circulation change: stronger ozone depletion in late spring generally leads to positive trend in SAM index in austral summer, resulting in poleward displacement of midlatitude jet and poleward widening of the Hadley cell. These changes are comparable to or even larger than those associated with greenhouse gas increase. In particular, it is found that inter-model spread of future projection of SAM index is largely explained by uncertainty in Antarctic stratospheric temperature change.
Using observations, it is further shown that Antarctic ozone hole has affected not only the long-term climate change but also the inter-annual variability of SH surface climate. A significant negative correlation is observed between September ozone concentration and the October SAM index, resulting in systematic variations in precipitation and surface air temperature throughout the SH. This time-lagged relationship is comparable to and independent of that associated with El Niño-Southern Oscillation and the Indian Ocean Dipole Mode, suggesting that SH seasonal forecasts could be improved by considering Antarctic stratospheric variability
Monday 20th January, 10:00am - 11:00am, Conference/Meeting Rooms, 9th floor east, 700 Collins St
Findings from sustained observations off northern Chile - the long (trends) and the short (diurnal)
Woods Hole Oceanographic Institution
Since October 2000, a well-instrumented surface mooring has been maintained some 1,500 km west of
the coast of northern Chile, roughly in the location of the climatological maximum in marine stratus clouds. The first
nine years of the data have been carefully and consistently quality controlled. Statistically significant increases in
wind stress and decreases in annual net air-sea heat flux and in latent heat flux have been observed. If the increased
oceanic heat loss continues, the region will within the next decade change from one of net annual heat gain by the
ocean to one of neat annual heat loss. Already, annual evaporation of about 1.5 m of sea water a year acts to make
the warm, salty surface layer more dense. Of interest is examing whether or not increased oceanic heat loss has the
potential to change the structure of the upper ocean and potetnially remove the shallow warm, salty mixed layer that now
buffers the atmosphere from the interior ocean. Insights into how that warm, shallow layer is formed and maintained
come from looking at oceanic response to the atmosphere at diurnal tie scales. Restratification each spring and summer
is found to depend upon the occurrence of events in which the trade winds decay, allowing diurnal warming in the
near-surface ocean to occur, and when the winds return resulting in a net upward step in sea surface temperature.
This process is proving hard to accurately model.
A PDF copy of all the presented seminars can be found at the "Find Seminar Presentation Documents..." link at the top of the page (available to BoM staff only). Seminars for previous years can be found at the "Goto list of BMRC seminars for ..." site at the top of the page. In addition, a list of actual videos from some previous seminars is held in the library and can be found on the
catalogue by entering Series: BMRC,
Format: Video. If you would like to have a talk videotaped please contact the
seminar coordinator. Note: as of 2005, it is standard practice for all seminars to be recorded as wmv movies,
with the permission of the presenter.
If you would like to know more details of coordinating seminars (if, for example,
you are hosting a visitor who will be giving a seminar and the regular seminar coordinator is not available),
have a look at the document, "Instructions for CAWCR Seminar Coordinator"