ORCID Profile
0000-0002-6111-8497
Current Organisation
Australian Bureau of Meteorology
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Publisher: Informa UK Limited
Date: 2008
Publisher: American Meteorological Society
Date: 12-02-2020
Abstract: The impact of Doppler radar wind observations on forecasts from a developmental, high-resolution numerical weather prediction (NWP) system is assessed. The new 1.5-km limited-area model will be Australia’s first such operational NWP system to include data assimilation. During development, the assimilation of radar wind observations was trialed over a 2-month period to approve the initial inclusion of these observations. Three trials were run: the first with no radar data, the second with radial wind observations from precipitation echoes, and the third with radial winds from both precipitation and insect echoes. The forecasts were verified against surface observations from automatic weather stations, against rainfall accumulations using fractions skill scores, and against satellite cloud observations. These methods encompassed verification across a range of vertical levels. Additionally, a case study was examined more closely. Overall results showed little statistical difference in skill between the trials, and the net impact was neutral. While the new observations clearly affected the forecast, the objective and subjective analyses showed a neutral impact on the forecast overall. As a first step, this result is satisfactory for the operational implementation. In future, upgrades to the radar network will start to reduce the observation error, and further improvements to the data assimilation are planned, which may be expected to improve the impact.
Publisher: Wiley
Date: 27-02-2013
DOI: 10.1002/MET.1378
Publisher: CSIRO Publishing
Date: 28-08-2020
DOI: 10.1071/ES19036
Abstract: The effect of synthetic ‘bogus’ tropical cyclone (TC) central pressure observations on TC Owen was tested in a convective-scale numerical weather prediction (NWP) system with hourly 4D-Var assimilation. TC Owen traversed the Gulf of Carpentaria over 10–14 December 2018, entering from the east and briefly making landfall on the western edge before reversing course and retracing its path east to cross the northern tip of Queensland. The Australian Bureau of Meteorology runs a high-resolution NWP model centred over Darwin, which covers much of the Gulf of Carpentaria. The next-generation developmental version of this model includes data assimilation. Therefore, when TC Owen presented the opportunity to investigate the simulation of a TC within the domain, the developmental system was run as a case study. The modelled cyclone initially failed to intensify. The case study was then repeated including assimilation of bogus central pressure observations. This new run showed a large improvement in the intensity throughout the simulation however, the TC track was not substantially improved. This demonstration of the potential impact of using synthetic observations may guide whether the development of a bogus observation source with sufficiently low latency for use in an hourly-cycling system should be prioritised.
Publisher: Elsevier BV
Date: 04-2007
Publisher: Elsevier BV
Date: 04-2009
Publisher: Copernicus GmbH
Date: 24-05-2019
Abstract: Abstract. The Bureau of Meteorology Atmospheric high-resolution Regional Reanalysis for Australia (BARRA) is the first atmospheric regional reanalysis over a large region covering Australia, New Zealand, and Southeast Asia. The production of the reanalysis with approximately 12 km horizontal resolution – BARRA-R – is well underway with completion expected in 2019. This paper describes the numerical weather forecast model, the data assimilation methods, the forcing and observational data used to produce BARRA-R, and analyses results from the 2003–2016 reanalysis. BARRA-R provides a realistic depiction of the meteorology at and near the surface over land as diagnosed by temperature, wind speed, surface pressure, and precipitation. Comparing against the global reanalyses ERA-Interim and MERRA-2, BARRA-R scores lower root mean square errors when evaluated against (point-scale) 2 m temperature, 10 m wind speed, and surface pressure observations. It also shows reduced biases in daily 2 m temperature maximum and minimum at 5 km resolution and a higher frequency of very heavy precipitation days at 5 and 25 km resolution when compared to gridded satellite and gauge analyses. Some issues with BARRA-R are also identified: biases in 10 m wind, lower precipitation than observed over the tropical oceans, and higher precipitation over regions with higher elevations in south Asia and New Zealand. Some of these issues could be improved through dynamical downscaling of BARRA-R fields using convective-scale ( km) models.
Publisher: Wiley
Date: 29-11-2010
DOI: 10.1002/MET.174
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.22499/3.6901.009
Publisher: Informa UK Limited
Date: 11-10-2010
Publisher: American Meteorological Society
Date: 04-2011
Abstract: The assimilation of Doppler radar radial winds for high-resolution NWP may improve short-term forecasts of convective weather. Using insects as the radar target, it is possible to provide wind observations during convective development. This study aims to explore the potential of these new observations, with three case studies. Radial winds from insects detected by four operational weather radars were assimilated using three-dimensional variational data assimilation (3D-Var) into a 1.5-km resolution version of the Met Office Unified Model, using a southern U.K. domain and no convective parameterization. The effect on the analyzed wind was small, with changes in direction and speed up to 45° and 2 m s−1, respectively. The forecast precipitation was perturbed in space and time but not substantially modified. Radial wind observations from insects show the potential to provide small corrections to the location and timing of showers, but not to completely relocate convergence lines. Overall, quantitative analysis indicated the observation impact in the three case studies was small and neutral. However, the small s le size and possible ground clutter contamination issues preclude unequivocal impact estimation. The study shows the potential positive impact of insect winds future operational systems using dual-polarization radars that are better able to discriminate between insects and clutter returns should provide a much greater impact on forecasts.
Publisher: IEEE
Date: 09-2013
Publisher: Elsevier BV
Date: 09-2009
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/MF05247
Abstract: The Perth Canyon is a focal feeding area for pygmy blue whales on the Western Australian coast. Studies aimed at elaborating oceanographic mechanisms within the canyon were conducted between 2002 and 2005. Strings of temperature loggers set around the canyon rim were used to examine the water column’s response to climatological forcing, current meanders, upwelling and downwelling. Six moorings were positioned on a plateau in 500 m of water on the northern canyon rim, and one was positioned at the canyon head. Loggers were positioned to s le the whole water column, including the Leeuwin Current and Undercurrent. Moorings revealed spatial temperature differences between the plateau and canyon head. Observed temperature features ranged temporally from seasonal to day. Seasonal changes in water temperature agreed with published Leeuwin Current studies: for ex le, mixed layer and stratification changes were apparent. Other observed temperature changes were related to Leeuwin Current movement and wind forcing such as the summer sea breeze and winter storms. Storms induced mixing, re-stratification, downwelling and upwelling as the wind changed direction and strength. Changes lasting a day were associated with diurnal sea breezes, internal waves and possibly solitary waves. Bottom loggers indicated that upwelling and downwelling events each occurred up to 20% of the time.
Publisher: American Meteorological Society
Date: 07-2015
DOI: 10.1175/JTECH-D-14-00206.1
Abstract: The Australian Bureau of Meteorology’s operational weather radar network comprises a heterogeneous radar collection covering erse geography and climate. A naïve Bayes classifier has been developed to identify a range of common echo types observed with these radars. The success of the classifier has been evaluated against its training dataset and by routine monitoring. The training data indicate that more than 90% of precipitation may be identified correctly. The echo types most difficult to distinguish from rainfall are smoke, chaff, and anomalous propagation ground and sea clutter. Their impact depends on their climatological frequency. Small quantities of frequently misclassified persistent echo (like permanent ground clutter or insects) can also cause quality control issues. The Bayes classifier is demonstrated to perform better than a simple threshold method, particularly for reducing misclassification of clutter as precipitation. However, the result depends on finding a balance between excluding precipitation and including erroneous echo. Unlike many single-polarization classifiers that are only intended to extract precipitation echo, the Bayes classifier also discriminates types of nonprecipitation echo. Therefore, the classifier provides the means to utilize clear air echo for applications like data assimilation, and the class information will permit separate data handling of different echo types.
Publisher: Elsevier BV
Date: 04-2007
Publisher: American Meteorological Society
Date: 08-2018
DOI: 10.1175/JTECH-D-17-0183.1
Abstract: A new quality control system, primarily using a naïve Bayesian classifier, has been developed to enable the assimilation of radial velocity observations from Doppler radar. The ultimate assessment of this system is the assimilation of observations in a pseudo-operational numerical weather prediction system during the Sydney 2014 Forecast Demonstration Project. A statistical analysis of the observations assimilated during this period provides an assessment of the data quality. This will influence how observations will be assimilated in the future, and what quality control and errors are applicable. This study compares observation-minus-background statistics for radial velocities from precipitation and insect echoes. The results show that with the applied level of quality control, these echo types have comparable biases. With the latest quality control, the clear air observations of wind are apparently of similar quality to those from precipitation and are therefore suitable for use in high-resolution NWP assimilation systems.
No related grants have been discovered for Susan Rennie.