Engineering Meteorology: Making informed decisions to deliver project solutions

Michael Green, Engineering Meteorologist with Aurecon, discusses how Engineering Meteorology can assist in project challenges and help improve the resilience of operational and infrastructure design across many industries.

In this article Michael will outline how Aurecon has applied Engineering Meteorology with our project partners to date, and our vision of how it can be applied to a wider range of engineering applications.

Planning for extreme weather and climate change

We are all seeing extreme weather events around the globe with increasing frequency in news broadcasts. In Australia during January 2013 widespread flooding, destructive winds, and bushfires were experienced, and the Bureau of Meteorology had to add a new colour to 54°C to the top of its temperature scale to accommodate the intense temperatures forecast and experienced in some inland areas.

In other parts of the world super-storm 'Sandy' devastated parts of coastal northeast USA, snow fell in unlikely parts of the Middle East, severe flooding occurred in Mozambique, and continental USA had its warmest year on record in 2012. The theory that global warming will affect both day-to-day weather as well as long term climate indicators looks to be becoming a reality.

The carbon dioxide level in the atmosphere from human activity continues to increase, and there is no sign that emission rates will reduce in the near future.

The responsibility of mitigating the effects of resulting climate change looks likely to fall on consultancies like Aurecon to provide solutions for adaption and resilience, especially in already vulnerable environments such as parts of Africa, Asia and Australia.

From Renewables to Water and beyond

Through applied atmospheric science, Engineering Meteorology can help provide solutions to engineering challenges where engineers and scientists can work together to responsibly plan and design for ways of dealing with current and future weather and climate conditions.

Engineering Meteorology has evolved from its roots in the renewable energy sector, where it has been extensively and successfully used to find and assess potential renewable energy project sites. Four European offshore wind farms have now been financed using Aurecon's sophisticated mesoscale modelling as the basis of the bankable energy yield prediction. Wind assessments using mesoscale modelling have enabled our clients around the world to make well informed commercial decisions at a very early stage of their projects' development lifecycle.

Figure 1 shows a validation example over the southern part of the North Island of New Zealand where mesoscale modelling was combined with Geographic Information System (GIS) data, incorporating terrain analysis, land use, protected areas, residential sites, and national parks, to determine the best sites for potential wind energy development across a wide area. Highly suitable areas are shown in red and are validated by existing wind farms.

While Engineering Meteorology has been used widely in Aurecon’s renewable energy sector and especially for wind energy, it has also recently been used in a number of water resources applications such as:

• Heavy rainfall prediction for use in flood prediction models in areas prone to flooding
• Rainfall modelling for assistance in dam inflow analysis and spatial variation of rainfall in catchments
• Rainfall modelling to obtain high resolution spatial analysis for use in landslide assessments for vulnerable transport links
• Using rainfall modelling and runoff analysis to create long term reference water resource flow data to reduce the uncertainty for proposed hydroelectricity generation

Other examples of Aurecon's Engineering Meteorology advisory services delivering value to our clients include:

• An analysis of the impact of future global warming on extreme wind events for design considerations of a Sydney precinct development
• Potential dust dispersion analysis from an Iceland volcano provided key input for risk assessment of air travel disruptions for a major world sporting event
• A high level wind impacts study on an urban mall development in Hamilton, New Zealand provided a cost effective way to provide design solutions to mitigate the effects of wind
• Provision of meteorological information at the eastern end of the remote Milford tunnel in New Zealand provided key information for fire modelling where there is no actual reliable weather and climate information
• Delivery of project site-specific forecasts for clients in New Zealand to establish a 'weather window' for projects with specific technical constraints. These high precision forecasts saved our clients money by avoiding delay and allowing critical work to happen in marginal conditions under a reliable, tailored weather forecast.
• Wind analysis in a remote part of South Africa to determine potential impacts of dust dispersion from mining activity on a solar farm. This gave our client certainty about the minimal impact of dust on the solar farm.

Aurecon has expanded the scope of Engineering Meteorology so that it can be used across all of the industries in which we operate. These can be considered as three themes:

• Engineering Meteorology technical advice for better project outcomes
• Meteorological data for informed decision making
• Future climate change modelling for adaption and resilience

Engineering Meteorology technical advice for better project outcomes

The development of the urban comfort assessment tool is an example of an Engineering Meteorology initiative and was developed in association with HUB-id. The urban comfort index can be used to assess and visualise comfort for precinct designs and can also measure the effects of mitigation factors proposed to improve comfort in specific areas. The index incorporates computational fluid dynamic (CFD) modelling for high resolution wind analysis, sun and shade modelling, solar radiation, sun angle, and temperature.

Figure 2 is an example of an urban comfort index which incorporates various meteorological parameters.

Aurecon's Engineering Meteorological technical advisory team can answer these and other questions on weather, climate and climate change which could have an influence on many of Aurecon's diverse projects located around the world:

• Is rainfall data from a location in Vietnam representative for storm water modelling 80 km to the southwest?
• What is the best weather information available for a project in Oman to optimise its design and operational efficiency?
• Is weather and climate data from Nairobi Airport representative for a located project 100 km to the north?
• Does the northwest part of Mozambique get impacted by tropical storms and hurricanes, and if so how often and how intense are these storms?
• What are the wind conditions at 100 m above ground level for the dispersion of pollutants from a proposed smoke stack in a remote location in Western Australia?
• What is the likely effect of global warming on rainfall on a community development in northeast South Africa in 50 years' time?
• Is there a way of assessing relative urban comfort for a new precinct development in New Zealand?
  
  

Meteorological data for informed decision making

Mesoscale modelling utilises the sophisticated weather model Weather Research and Forecasting (WRF) to simulate past weather at high resolution for anywhere in the world. WRF can be used to assess situations from individual extreme weather events to obtaining long term meteorological datasets.

Aurecon acquired its mesoscale modelling capability in 2006 from the University of Canterbury's Centre for Atmospheric Research based in Christchurch, New Zealand. Aurecon has continued to develop this capability and initially commercialised it for renewable energy resource assessment.

Mesoscale modelling has the ability to generate reliable data in remote areas or in emerging economies where existing weather and climate information is sparse or non-existent. Provision of data can be at a specific location or over a wider area. Any weather parameter can be obtained from the mesoscale model output such as temperature, rainfall, snow depth and solar radiation - for example, so it has scope to be used widely across Aurecon’s service groups.

Water, future gold

Mesoscale modelling has proven synergies with the Water industry and has strong potential in the following areas:

• Assessment of the spatial variation of rainfall across catchments for hydropower generation and irrigation
• Rainfall harvesting applications in vulnerable locations
• Assessment of rainfall in different climate scenarios such as in La Nina and El Nino events
• Production of synthetic rainfall data at specific locations for hydrology models
• Dam reliability, spill risk, and use in general water management
• Coastal management and engineering applications including coastal flooding and shoreline change assessments by incorporating coastal and offshore winds into wave models
• Port design considerations in remote locations
• Ground water recharge analysis
• Water budget assessments

Figure 3 shows an example of a long term rainfall map centred over Swaziland which shows the spatial variation of rainfall over a wide area. Similar analyses have been done for extreme rainfall events that caused severe flooding in Mozambique to identify areas prone to higher rainfall and which could help assist in optimising flood forecasting systems for vulnerable areas.

Data for any meteorological parameter can be obtained to give hourly, or daily or monthly data at specific locations.

Figure 4 shows a typical comparison of modelled and observed rainfall totals for a storm event in complex terrain in the northwest part of the New Zealand’s South Island.

Future climate change modelling for adaption and resilience

Anthropogenic increase in atmospheric carbon dioxide levels are a significant contributor to temperature increases that are being observed around the world and this in turn will have an effect on rainfall and wind. The effects of climate change will be on both long-term trends and the frequency and magnitude of short term extreme weather events¹.

Adaption and resilience measures against longer term climate change and extreme weather events are likely to be different, and a complicating factor is that the changes such as in rainfall, temperature and wind are not expected to be homogeneous and may even vary at a regional level.

Regional Climate Modelling (RCM) is a tool which Aurecon uses in conjunction with Environmental Research and Innovation Consultancy (EnRICo), which is closely linked to the University of Canterbury.

RCM is a tool to assess the impacts of climate change to 2050 and beyond by incorporating the latest Intergovernmental Panel on Climate Change (IPCC) CO2 emission scenarios and sophisticated modelling tools for downscaling to a regional level.

RCM can provide an evaluation of the impact of climate change on rainfall, temperature and wind for anywhere in the world. This modelling capability provides a key point of difference for Aurecon when working in regions vulnerable to climate change.

While there are uncertainties regarding climate change, RCM is a powerful tool to narrow the uncertainty band by assessing numerous climate scenarios at a level that highlights key spatial differences at a regional scale.

Figure 5 shows an example of the increased detail obtained from using RCM as opposed to the low resolution global climate predictions.

Identified Regional Climate Modelling applications include:

• Design considerations for large and long life projects such as for hydro-electricity, levee and dam design, irrigation schemes and transport infrastructure especially in coastal regions
• Planning for sustainability, adaptively and resilience for communities
• Assessment of potential impacts on future water supply and for crop adaption possibilities
• Risk and insurance assessment work
• Accounting for future climate scenarios in design assumptions, for example temperature change and extreme rainfall

EnRICo has carried out regional climate predictions for climate change impact assessment in Indonesia², and also tuned and validated successfully the model they are using for the Eastern Mediterranean region³ down to a spatial resolution of 10 km, ten times higher than typical global climate model resolutions.

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