science

SAFE AIR

SAFE AIR is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand SAFE AIR rather than just read about it. In short: SAFE AIR (Simulation of Air pollution From Emissions Above Inhomogeneous Regions) is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously or intermittently from point, line, volume and area sources. It adopts an integrated Gaussian puff modeling system.

Key takeaways

SAFE AIR belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SAFE AIR to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SAFE AIR from memory before moving on to harder problems.

Reference excerpt

SAFE AIR (Simulation of Air pollution From Emissions Above Inhomogeneous Regions) is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously or intermittently from point, line, volume and area sources. It adopts an integrated Gaussian puff modeling system. SAFE AIR consists of three main parts: the meteorological pre-processor WINDS (Wind-field Interpolation by Non Divergent Schemes) to calculate wind fields, the meteorological pre-processor ABLE (Acquisition of Boundary Layer parameters) to calculate atmospheric parameters and a lagrangian multisource model named P6 (Program Plotting Paths of Pollutant Puffs and Plumes) to calculate pollutant dispersion. SAFE AIR is included in the online Model Documentation System (MDS) of the European Environment Agency (EEA) and of the Italian Agency for the Protection of the Environment (APAT).

History SAFE AIR is developed, maintained, and distributed by the Department of Physics (DIFI) of the University of Genoa, Italy. The first version of SAFE AIR was released in 1996. The current version II was released in 2003 and runs both in the Microsoft Windows and Unix environment. It has a Fortran codebase.

Input data

Topographic data Orography Roughness Displacement level Land sea mask

Meteorological data Ambient temperature Wind direction Wind speed Atmospheric stability classes (A through G) Atmospheric pressure Cloud cover Albedo

Source data Position Dimension Release height of the emission source Emission discharge rate of primary and secondary pollutants Volume flow rate of total gas emission Exit gas temperature Exit gas speed

Features and capabilities of SAFE AIR The model includes algorithms which take into account: downwash effects of nearby buildings within the path of the dispersing pollution plume; effects of complex terrain; effects of coastline locations; wet deposition, gravitational settling and dry deposition; first order chemical reactions; pollution plume rise as a function of distance; averaging time ranging from very short to annual. The system also includes a meteorological data input preprocessor, named ABLE. The model is capable of simulating passive or buoyant continuous plumes as well as short duration puff releases. It characterizes the atmospheric turbulence either by the boundary layer depth and the Monin-Obukhov length or by the Pasquill class.

See also Atmospheric dispersion modeling Bibliography of atmospheric dispersion modeling Atmospheric Studies Group List of atmospheric dispersion models

References

E. Canepa, F. Modesti, and C.F. Ratto (2000) Evaluation of the SAFE_AIR code against air pollution field and laboratory experiments. Atmos. Environ., 34, 4805-4818. E. Canepa, L. Dallorto, and C.F. Ratto (2000) About the plume rise description in the dispersion code SAFE_AIR. Int. J. Environ. Pollut., 14, 235-245. E. Canepa and P.J.H. Builtjes (2001) Methodology of model testing and application to dispersion simulation above complex terrain. Int. J. Environ. Pollut., 16, 101-115. E. Canepa and C.F. Ratto (2003) SAFE_AIR algorithms to simulate the transport of pollutant elements: a model validation exercise and sensitivity analysis. Environ. Model. Software, 18, 365-372. E. Canepa, F. D’Alberti, F. D’Amati, and G. Triacchini (2007) The GIS-based SafeAirView software for the concentration assessment of radioactive pollutants after an accidental releases. Science Total Environ., 373, 32-42. [1] M. Cavallaro, E. Canepa, and E. Georgieva (2007) The SAFE_AIR II dispersion model: description and statistical evaluation of its dispersion module against wind tunnel data from area sources. Ecolog. Model., 202, 547-558. [2]

Further reading For those who are unfamiliar with air pollution dispersion modelling and would like to learn more about the subject, it is suggested that either one of the following books be read:

Turner, D.B. (1994). Workbook of atmospheric dispersion estimates: an introduction to dispersion modeling (2nd ed.). CRC Press. ISBN 978-1-56670-023-8. www.crcpress.com Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion (4th ed.). self-published. ISBN 978-0-9644588-0-2.

External links SAFE_AIR Version II Release 1.1 User’s Guide

Worked examples

Example 1 — a first encounter with SAFE AIR

Start with the simplest possible case. Write down what SAFE AIR claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to SAFE AIR before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about SAFE AIR ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of SAFE AIR

In research: SAFE AIR appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses SAFE AIR in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: SAFE AIR is common in secondary-school and first-year university syllabi. It links to neighbouring topics Atmospheric dispersion modeling, so understanding it makes those chapters shorter.
In everyday life: Look for SAFE AIR outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study SAFE AIR in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SAFE AIR means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain SAFE AIR out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SAFE AIR in simple terms?

Why does SAFE AIR matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study SAFE AIR?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on SAFE AIR.