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National Meteorological Operations Centre

The role of the National Meteorological Operations Centre (NMOC) is to:

• serve as the central real-time operational hub for Australia's national weather service by:
  • maintaining a nationwide weather watch
  • providing centralised guidance products to the Regional Forecasting Centres
  • issuing a range of analysis and prediction products
  • supporting the operational communications and computing infrastructure
• perform the international functions of:
  • a World Meteorological Centre (WMC) and Regional Specialised Meteorological Centre (RSMC) of the World Meteorological Organisation (WMO) World Weather Watch (WWW),
  • a Regional Area Forecast Centre (RAFC) of the International Civil Aviation Organisation (ICAO) World Area Forecast (WAF) System.
  • a National Data Processing Centre of the WMO Integrated Global Ocean Services System
• produce a definitive archive of Australian weather.

OPERATIONS
The main functions of NMOC are:

• providing a suite of high quality analysis and prediction products to support meteorological and marine weather and climate services. Some products are produced manually but most products derive from computer models of the atmosphere and ocean.
• assessing and implementing upgrades to operational numerical models, and providing relevant verification statistics and evaluations of model performance
• ensuring the receipt and transmission of meteorological data and products within Australia and internationally and contributing to the quantity and quality monitoring of data exchanged internationally
• preparing and disseminating products to support domestic and international aviation
• serving as a WMO Regional Specialised Meteorological Centre (RSMC) for Environmental Emergency Response. In this role NMOC can operate an atmospheric transport model to predict the movement of atmospheric contaminants such as smoke, volcanic ash or radioactive debris.
• providing a Help Desk to provide support to users of the Bureau's national computing and communications infrastructure
• working with Services areas in looking for new and innovative ways to enhance Bureau services, particularly in applications of numerical model output such as UV-B prediction or tropical cyclone storm surge models.

Meteorological Systems Development:
The task of this group is to test, implement, monitor and maintain the suite of NMOC's operational meteorological models and supports the Darwin RSMC with its computer analysis and prediction systems.

Software Systems:
This group is responsible for the management of the software standards throughout the operational suite, and acts as the systems integrator, liaising closely with those areas of the Bureau developing systems for operational implementation. This group is also responsible for the administration and development of the real-time database.

Oceanographic Systems Development:
This group's task is to test, implement, monitor and assist in the development of models and numerical techniques for the analysis and prediction of sea state and ocean structure, as well as to manage and develop access to new types of oceanographic data.

Real-time Data Management:
This group focuses on the development of systems to meet our requirements and obligations for national and international data. It also carries out data quality and quantity monitoring and produces performance statistics of the numerical systems.

OPERATIONAL NUMERICAL ANALYSIS AND PREDICTION SYSTEMS

NMOC runs numerical models over several domains to provide analyses and predictions for the atmosphere and ocean on a range of time-scales. The models have been developed in the Bureau of Meteorology Research Centre. The most detailed predictions are for targeted areas over the Australian region and extend to 36 or 48 hours. Medium range predictions to 7 days are made with the global model. NMOC also runs numerical models to predict the state of the ocean. These range from products relevant to marine meteorological forecasts such as surface wind and wave forecasts to coupled atmosphere- ocean systems used in the preparation of seasonal outlooks. Many diagnostic fields are available from the models to assist in forecasting such as stability indices and deep layer mean winds. The models are used with other computer systems to produce guidance on sea state, atmospheric dispersion of contaminants, and UV-B prediction.

GASP (Global AnalysiS and Prediction)

The global model (GASP) uses spectral numerical techniques and is currently run with triangular wave number T_L239 truncation (approximately 85 km horizontal resolution). The model's domain is global, and has 29 levels from the surface to 10 hPa. Analyses of observations are made at 6-hourly intervals and twice per day forecasts are generated out to 7 days. The GASP system provides boundary conditions for the limited area systems and also provides the surface winds used in the global sea state prediction scheme.

LAPS (Limited Area Prediction System)

The prediction component of LAPS is a grid point primitive equation model with a grid spacing of 0.375^o (about 37 km) in the horizontal, and 29 levels in the vertical, from the surface to 50 hPa. The lateral boundary conditions are obtained from the GASP system. The analysis component involves a 6 hourly data assimilation cycle. The system operates with a short data cut-off time to ensure timely delivery of forecast guidance to forecast offices. Consequently, the data analysis stage places special emphasis on the use of locally derived satellite observations.

LAPS operates over several telescoping domains. The largest extends from about 17^oN to 65^oS and 65^oE to 184^oE and is used for broad-scale predictions over the Australian region to 48 hours.

Several Meso-LAPS systems operate to provide finer scale predictions for sub-areas of the larger Australian region domain. The resolution of this next level is 0.125^o (about 12 km). Several test systems at an even finer scale of 0.05^o (5 km) are in test mode for areas round Sydney and Melbourne. These fine-scale predictions are being used by BMRC and CSIRO in a test of an air quality prediction system.

TLAPS (Tropical Limited Area Prediction System) (A joint effort between NMOC and Northern Territory Regional Office)

TLAPS is a version of LAPS customised to describe the tropical atmosphere. In particular an attempt is made to capture areas of convection that are observable as cloud formations on satellite imagery and which can lead to the development of tropical depressions. In addition to available conventional data, input to the analysis includes bogus moisture values derived from satellite cloud imagery. Tropical Cyclones are incorporated into the analysis using a bogus system operated by Darwin RSMC staff. The first guess field for this analysis is a forecast from GASP. TLAPS currently operates over the domain 44^oN to 45^oS and 70^oE to 189^oE with a grid spacing of 0.375^o.

WAM (WAve Model)

The WAM model solves equations for the directional wave spectrum on a regular grid based on local wind input, wave dissipation, nonlinear wave-wave interactions and propagation of waves from nonlocal sources (swell).

The Wave Model is run over three domains each run twice a day and including a 12 hour assimilation period using satellite derived wave height data. A global model at 3 degree resolution forced by surface winds from GASP produces forecasts generated out to 6 days and boundary conditions for the regional system. Regional (1 degree resolution) and Meso- scale (0.25 degree resolution) versions of the model using surface wind forecasting from the respective atmospheric models are used for local forecasting out to 48 hours.

Storm Surge Model

Strong onshore winds associated with tropical cyclones and other intense storms produce a rise in the sea level which can be the cause of a lot of major flooding. A system has been set up based on a simple ocean model to forecast the storm surge associated with tropical cyclones. The wind forcing is based on an ideal distribution calculated from the central pressure of the cyclone at any time and the radius of maximum winds.

Sea Surface Temperature (SST) Analysis

A global SST analysis is performed weekly on a 1 degree resolution grid. In the analysis measurements of the sea temperature from voluntary observing ships and drifting buoys are used to remove biases in remotely sensed data from satellites before being blended into the final product. A finer resolution product for the Australian region is produced daily based on locally received satellite data. The global analysis is used by operational atmospheric models and in the production of climate forecasts and seasonal outlooks.

Sub-surface Temperature Analysis

An analysis of monthly temperatures at a number of levels in the ocean down to 500 metres is updated weekly. This analysis uses data from moored buoys, bathythermograph reports from the ship-of-opportunity program and profiling floats.

Coupled Ocean-Atmosphere Models

NMOC runs an operational coupled ENSO forecast model. This is an intermediate class model which is initialised using sub-surface ocean data and surface wind data. It produces forecasts of the SST anomaly in the central Pacific Ocean out to 2 years which are used operationally in climate assessments and outlooks.

Other numerical model output
An atmospheric transport system can be run on demand to produce forecast trajectories and concentrations for volcanic ash, smoke, radioactive debris from nuclear accidents or atmospheric contaminants arising from other environmental emergencies.

Upper wind and temperature forecasts for the aviation industry.

Analysis and forecast charts derived from the global analysis and prediction models of several international centres, including the European Centre for Medium Range Forecasts (ECMWF), United States, Japan and the United Kingdom. Forecasts out to 36 hours of the UV-B index by coupling an atmospheric UV radiation scheme to analyses and predictions of vertical profiles of ozone concentration and temperature.

Statistical guidance (Model Output Forecasts), derived from the numerical model predictions, of weather elements such as maximum and minimum temperatures, probability of rainfall and cloud cover.

Samples:
Samples of some of these models may be found on the Bureau's ftp site (login anonymously to ftp.bom.gov.au) under directory sample/bucket/:

• GASP: IDY01001.nc, IDY01021.nc, IDY01075.nc (each file 39MBytes)
• LAPS: IDY02001.nc, IDY02021.nc, IDY02036.nc (each file 13MBytes)