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A method is introduced for issuing tsunami warnings in the Australian region based on numerical model output. The method considers
the maximum modelled wave amplitude within pre-defined coastal waters zones and uses this as a proxy for the potential impact
on the coast. A three-level stratified warning is proposed: (1) No threat, (2) Marine threat and (3) Land threat. This method
is applied to several case studies and the resulting warning characteristics are shown. While the method has its limitations,
it is a significant improvement over current operational warning strategies, which are typically based solely on the magnitude
of the earthquake and distance from the source. 相似文献
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Jose Henrique G. M. Alves Diana J. M. Greenslade Michael L. Banner 《Journal of Atmospheric & Ocean Science》2002,8(4):239-267
The impact of a modified parametric form of the dissipation source function S ds on the skill of an operational spectral wind-wave model is investigated. Numerical experiments are made with a version of the WAM model presently used operationally by the Australian Bureau of Meteorology to produce sea-state forecasts within the Australian region. Performances of wave hindcasts obtained using several alternative forms of this newly proposed dissipation source function are compared to those produced with forms of S ds commonly used operationally. A new ad hoc technique to compare modelled and observed wave spectra is introduced to assess the quality of calculated one-dimensional frequency spectra.
Our results indicate that wave model performance in terms of integral spectral parameters, such as the significant wave height H s , may benefit from improved parameterisations of the dissipation source term S ds . On the other hand, we also found that model performance was relatively poor in terms of predictions of the one-dimensional frequency spectrum, regardless of the chosen form of S ds . These results suggest that further refinements of the dissipation source term are strongly dependent on improved parametrisations of the nonlinear interactions source term S nl . 相似文献
Our results indicate that wave model performance in terms of integral spectral parameters, such as the significant wave height H s , may benefit from improved parameterisations of the dissipation source term S ds . On the other hand, we also found that model performance was relatively poor in terms of predictions of the one-dimensional frequency spectrum, regardless of the chosen form of S ds . These results suggest that further refinements of the dissipation source term are strongly dependent on improved parametrisations of the nonlinear interactions source term S nl . 相似文献
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The impact of inhomogenous background errors on a global wave data assimilation system 总被引：1，自引：0，他引：1
One of the main limitations in current wave data assimilation systems is the lack of an accurate representation of the structure of the background errors. In this work, models for the observational error variance, background error variance and background error correlations are developed based on the results of previous studies. These are tested in a global wave data assimilation system and the resulting wave forecasts are verified against independent observations from buoys. Forecasts of significant wave height show substantial improvement over the Australian Bureau of Meteorology's current operational wave forecasting system. However, forecasts of peak period are not similarly improved. The regional impacts of the new assimilation scheme are found to vary on a seasonal basis. Overall, it is shown that the inclusion of a latitudinally dependent background error, and improved specification of the background and observational error variances can reduce the root-mean-square error of 24-hour forecast Significant Wave Height by almost 10%. 相似文献
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Forecasting of waves under extreme conditions such as tropical cyclones is vitally important for many offshore industries, but there remain many challenges. For Northwest Western Australia (NW WA), wave forecasts issued by the Australian Bureau of Meteorology have previously been limited to products from deterministic operational wave models forced by deterministic atmospheric models. The wave models are run over global (resolution 1/4°) and regional (resolution 1/10°) domains with forecast ranges of +?7 and +?3 day respectively. Because of this relatively coarse resolution (both in the wave models and in the forcing fields), the accuracy of these products is limited under tropical cyclone conditions. Given this limited accuracy, a new ensemble-based wave forecasting system for the NW WA region has been developed. To achieve this, a new dedicated 8-km resolution grid was nested in the global wave model. Over this grid, the wave model is forced with winds from a bias-corrected European Centre for Medium Range Weather Forecast atmospheric ensemble that comprises 51 ensemble members to take into account the uncertainties in location, intensity and structure of a tropical cyclone system. A unique technique is used to select restart files for each wave ensemble member. The system is designed to operate in real time during the cyclone season providing +?10-day forecasts. This paper will describe the wave forecast components of this system and present the verification metrics and skill for specific events. 相似文献
6.
Diana J. M. Greenslade Stewart C. R. Allen M. Arthur Simanjuntak 《Pure and Applied Geophysics》2011,168(6-7):1137-1151
A tsunami scenario database (T2) has recently been developed for use within the Joint Australian Tsunami Warning Centre (JATWC). This scenario database has proven to be a very useful tool for forecast guidance, issuing of tsunami warnings and general event analysis. In this paper, the T2 scenarios are described, and evaluated by comparing them with observations of sea level from tsunameters for a number of recent tsunami events. In general, the T2 scenario database performs very well in terms of predicting the arrival time of the tsunami and the wave amplitudes at tsunameter locations. 相似文献
7.
Many past studies have verified numerical simulations of tsunamis using only qualitative and subjective methods. This paper investigates the relative merits of several indices that can be used to objectively verify tsunami model performance. A number of commonly used indices, such as error in the maximum amplitude and root-mean-square error, are considered, as well as some further indices that have been developed for other specific applications. Desirable qualities of the indices are presented and these include computational efficiency, invariance when applied to tsunamis of any size or to time series of varying length (including relatively short series), and the ability to clearly identify a single best prediction from within a set of simulations. A scenario from the T2 tsunami scenario database is chosen as the control. From this, time series of sea-level elevations are extracted at designated test points located at a range of distances from the tsunami source region. Parameters of the T2 database are perturbed in order to examine the performance of the indices. Of the indices examined, several performed better than others, with Wilmott’s Index of Agreement and Watterson’s transformed Mielke index found to be the best. Combining data from multiple locations was shown to improve the performance of the indices. This study forms the basis for future evaluation of the indices using real observations of tsunamis. 相似文献
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This paper presents a comparison of two tsunami forecasting systems: the NOAA/PMEL system (SIFT) and the Australian Bureau of Meteorology system (T1). Both of these systems are based on a tsunami scenario database and both use the same numerical model. However, there are some major differences in the way in which the scenarios are constructed and in the implementation of the systems. Two tsunami events are considered here: Tonga 2006 and Sumatra 2007. The results show that there are some differences in the distribution of maximum wave amplitude, particularly for the Tonga event, however both systems compare well to the available tsunameter observations. To assess differences in the forecasts for coastal amplitude predictions, the offshore forecast results from both systems were used as boundary conditions for a high-resolution model for Hilo, Hawaii. The minor differences seen between the two systems in deep water become considerably smaller at the tide gauge and both systems compare very well with the observations. 相似文献
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Øyvind Breivik Jose Henrique Alves Diana Greenslade Kevin Horsburgh Val Swail 《Ocean Dynamics》2017,67(3-4):551-556
Following the 14th International Workshop on Wave Hindcasting and Forecasting and 5th Coastal Hazards Symposium in November 2014 in Key West, Florida, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 16 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. A general trend in the field has been towards closer integration between the wave and ocean modelling communities. This is also seen in this topical collection, with several papers exploring the interaction between surface waves and mixed layer dynamics and sea ice. 相似文献
10.
A New Tool for Inundation Modeling: Community Modeling Interface for Tsunamis (ComMIT) 总被引：2，自引：0，他引：2
V. V. Titov C. W. Moore D. J. M. Greenslade C. Pattiaratchi R. Badal C. E. Synolakis U. Kânoğlu 《Pure and Applied Geophysics》2011,168(11):2121-2131
Almost 5 years after the 26 December 2004 Indian Ocean tragedy, the 10 August 2009 Andaman tsunami demonstrated that accurate
forecasting is possible using the tsunami community modeling tool Community Model Interface for Tsunamis (ComMIT). ComMIT
is designed for ease of use, and allows dissemination of results to the community while addressing concerns associated with
proprietary issues of bathymetry and topography. It uses initial conditions from a precomputed propagation database, has an
easy-to-interpret graphical interface, and requires only portable hardware. ComMIT was initially developed for Indian Ocean
countries with support from the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the United States
Agency for International Development (USAID), and the National Oceanic and Atmospheric Administration (NOAA). To date, more
than 60 scientists from 17 countries in the Indian Ocean have been trained and are using it in operational inundation mapping. 相似文献