Average Temperature Projections, taken from the draft NCA, illustrates both the potential significance of climate change for structural engineering and why climate science cannot now quantitatively forecast future climate, weather and extreme events. The projections for the 21 st century are derived from global climate models that consider a variety of scenarios for economic development and control of greenhouse gas emissions Moss et al.
The historical trend of atmospheric CO 2 is shown in Figure 2. The CO 2 data red curve for Mauna Loa, measured as the mole fraction in dry air, constitute the longest record of direct measurements of CO 2 in the atmosphere. The black curve represents the seasonally corrected data. Greenhouse gas emissions in the 21 st century will depend upon worldwide private and public policy decisions and actions, which are unpredictable, but can be represented by scenarios such as those used in preparing Figure 1.
These activities may include recommendations for initiatives related to:. Engineers can join in research with climate and weather scientists to develop integrated models for climate, weather and extreme events National Academies , which, combined with observations, can give probabilistic guidance for the conditions for which structures should be designed, constructed, operated and maintained.
They will understand what makes weather happen and they will understand weather maps and charts. They will be able to critically watch the nightly weather forecast and be able to access available meteorological databases to make informed predictions of their own. 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. Figure 1 — Mesoscale modelling used to identify potential wind farms.
Other examples of Aurecon's Engineering Meteorology advisory services delivering value to our clients include:. 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:. 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. Figure 2 — An example of an urban comfort index. The most desirable locations are coloured green, yellow is comfortably warm, light blue is comfortably cool, red is uncomfortably hot, and dark blue is uncomfortably cold. 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:.
Mesoscale modelling utilises the sophisticated weather model Weather Research and Forecasting WRF to simulate past weather at high resolution for anywhere in the world. A common rule of thumb to anticipate dangerous winds is assuming that gusts have twice the average wind speed.
For instance, if the anemometer measures 15 mph, gusts will have a speed of around 30 mph. In projects that use tower cranes, the maximum wind speed for safe operation should be checked with the manufacturer. However, lifts are normally suspended when the wind speed approaches 20 mph, to avoid 40 mph gusts. Measuring wind direction is also very important since risks change depending on the direction from which the wind blows. In the case of tower cranes, the mechanical loading effects of the wind are determined by speed and direction.
For example, wind blowing from behind a crane tends to push the load away. This increases the swing radius, causing a higher bending load on the boom.
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