- AEOLIUSQ is derived from AEOLIUS
readme text
- Results can be stored in a file
- Features optional traffic speed units
- Users can employ their own emission factor q (g/km), instead of
the default emission factors
- Given the same input data, AEOLIUSQ should give the same results
as in Table 2c of the Nomograms paper by Buckland and Middleton (1999)
More about Aeoliusq
for an example of such results for a wind speed 2 m/s. Appendix 3
Running AEOLIUSQ from a floppy
disk:
Make a working copy of the original disk, then type a:
or c: depending on the drive used. Then type either aeoliusq
or AEOLIUSQ. After the introduction several prompts appear.
You must:
-
ENTER EITHER Y OR N (Default N is Return) TO USE A RESULTS FILE.
If N then no results file will be used; results only appear on the
screen. If Y then a results file must be used to store the new results.
The new results will be added to the file; information already on
the file will be retained. If the file does not exist a new file
will be created. The file and program are in the same disk/directory
-
ENTER A FILE NAME (8 characters long)
-
ENTER Y/N to accept the filename as being correct
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ENTER TODAYS DATE (max 24 characters)
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ENTER THE CURRENT TIME (max 24 characters)
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ENTER RUN DESCRIPTION (max 80 characters) to summarise the purpose
of the run, in the file
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ENTER THE UNITS FOR TRAFFIC SPEED (max 3 characters long ) units
are only m/s, kph, mph
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ENTER WIND SPEED LOCATION Y (DEFAULT: 10 m height), N(roof top)
The following entries are repeated as a cycle, once per run:
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ENTER A STREET WIDTH (between 10.0 and 30.0 metres)
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ENTER A STREET HEIGHT (between 10.0 and 30.0 metres)
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ENTER A TRAFFIC SPEED (between 5.0 and 15.0 m s-1 in metric units)
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ENTER NO. OF VEHICLES (between 1000 and 4000)
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AN HOUR An initial default is given of 2000 veh hr-1
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ENTER WIND SPEED (between 2 and 8 ms-1)
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ENTER POLLUTANT Enter one of ...NOx, CO, PM10, SO2, C6H6 or C4H6
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ENTER BACKGROUND - ambient value found in the town or city. *Note:
AEOLIUSQ now uses CO background in ppm
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ENTER YEAR From 1996 through to 2005. When outside these years,
supply an emission factor (> 0.0 e.g.1.80) g/km
To rerun program, after the prompt 'Do you wish to run again (Y/N)'
ENTER Y (Return defaults to Y) otherwise ENTER N. If Y is entered the
same prompts appear but the defaults are the previous values entered.
If N is entered, the run ends with the closing of the results file.
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Results are printed to the file using fixed column widths
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New row of column headings will be printed whenever a new pollutant
is selected
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Each pass through the above cycle of questions will generate one
line of results in the file
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Results file may be wider than an A4 page, so load results into
a spreadsheet where they can be displayed, manipulated and printed
for use in reports
AEOLIUSQ (version 4.7) has removed empirical quantities, because DMRB
(1999) now uses an annual averaging time for the traffic, and different
empirical rules to arrive at the surrogates for quantities in the UK
National Air Quality Strategy.
If the user of AEOLIUSQ wishes to apply the DMRB (1999) surrogate statistics
for air pollution quantities, care is needed to ensure the consistent
use of averaging times in the traffic data; an annual mean is now implied.
The validity or otherwise of combining the AEOLIUSQ canyon concentration
(obtained with an annual traffic estimate as per DMRB, 1999) with these
empirical surrogates has not been investigated. Some users may seek
to explore this; it will be advisable to validate any attempts by reference
to measurements.
An alternative (and possible preferable) route to annual mean concentrations
in a street canyon (and thence the application of the DMRB, 1999 surrogates)
will be to use AEOLIUSF Full on a set of 12 monthly data sets and to
form the annual mean of all values calculated through the year. The
latter procedure allows for some implied averaging of the full range
of meteorological conditions experienced in the study year.
Example results
Matching the 'nomograms' emissions
AEOLIUSQ has been used to reproduce the results published in the 'Nomograms'
paper by Buckland and Middleton (1999).
The emission factors in Appendix
3 were taken from the bottom row of Table 1b in their paper (ibid).
The calculated concentrations in Appendix
3 are the same as shown in their Table 2c for wind speed 2 m/s.
The screening program AEOLIUSQ Emission includes the value l =0.1 as
discussed in the paper (ibid).
Matching the DMRB (1999) emissions
The Design Manual for Roads and Bridges DMRB (1999) was revised to match
the requirements of the UK National Air Quality Strategy. The most important
changes were to:
-
Use annual mean traffic flows
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Provide surrogate statistics that start from annual mean concentration
and lead directly to estimates of air pollutant quantities in the
form required by the Strategy Objectives
-
Remove the background factor from the pollutant dispersion curve
Minor changes included some adjustments to the emission factors. In
Appendix 4 we
give results obtained from the AEOLIUSQ model. The emission factors
for light vehicles travelling at 100 km/h and base year 1996 have been
taken from DMRB (1999). We also ran the calculations at decreasing traffic
speeds, down to 5 km/h. Finally, an example appears in Appendix 2 for
2000 light vehicles per hour at speed 5 km/h.
Appendix 4 shows
how the reducing vehicle speed is accompanied by an emission from DMRB
(1999) that first decreases, then rises again at the slower speeds.
At the same time, AEOLIUSQ responds to the decreasing speed by gradually
reducing the amount of vehicle wake turbulence, which on its own causes
a gradual increase in calculated concentrations at small vehicle speeds
(cf Figure 5 in Buckland and Middleton, 1999).
Appendix 4 shows
the combined effects of both the increased emission factor and the decreased
wake turbulence as the speed is reduced to 5 km/h.
It is these two effects working together in AEOLIUSQ that mean for local
air quality management, congested street canyons are likely to figure
strongly in the debate about potential pollution 'hot-spots'. In DMRB
(1999) reduced vehicle speed only operates via the associated change
in emission factor; there being no wake variation effect.
Comparing AEOLIUSQ and DMRB (1999)
A direct comparison to see if AEOLIUSQ returns a concentration that
is greater than DMRB (1999) can be obtained as follows.
Consider the base case (1,000 light vehicles per hour, at 100 km/h using
year 1996 emissions). From Appendix
4 the canyon base case concentrations are 0.38-0.39 ppm CO, and
84-86 ppb NOx. The roadside concentrations (5m from road) in DMRB (1999)
are 0.254 ppm CO, and 55.9 ppb NOx.
This comparison shows that in the absence of any background contributions,
AEOLIUSQ is giving higher concentrations than DMRB (1999) beside an
open road. Furthermore, for a given emission factor, the slower the
vehicle speed, owing to the reducing wake dilution, the more AEOLIUSQ
is likely to exceed DMRB (1999) (which omits wake changes).
Caution: the above comparison is based upon an assumption that averaging
time does not feature significantly in the dispersion curve in DMRB
(1999); Middleton (1998) has discussed this in more detail elsewhere.
In our comparison, since the DMRB (1999) averaging time for the pollutant
concentration dispersion curve is effectively that of the traffic data,
and because we have assumed an hourly average traffic flow of 1000 vehicles
per hour, the above DMRB (1999) concentrations are effectively 1 hour
values. This is why they can be compared with the AEOLIUSQ results.
References
Buckland A T (1998), Validation of a street canyon model
in two cities Environmental Monitoring and Assessment Vol 52 pp. 255-267.
Buckland A T and Middleton D R (1999) Nomograms for calculating pollution
within street canyons Atmospheric Environment Vol 33 pp. 1017-1036
DMRB (1994) Design Manual for Roads and Bridges, vol. 11, sect. 3, part
1 Air Quality. Department of Transport, available from HMSO London 1995.
DMRB (1999) Design Manual for Roads and Bridges, vol. 11, sect. 3, part
1 Air Quality. Highways Agency, Department of Transport, Updated version
available from HMSO London early in 1999.
Hertel O and Berkowicz R (1989) Modelling pollution from traffic in
a street canyon. Evaluation of data and model development.
Report DMU LUFT A129. National Environmental Research Institute Rosskilde
Denmark
Manning A J, Nicholson K J, Middleton D R, Rafferty S C (1999) Field
study of wind and traffic to test a street canyon pollution model
Environmental Monitoring and Assessment (in press). Middleton D R (1998)
Dispersion Modelling: A guide for Local Authorities.
Met Office Turbulence and Diffusion Note No. 241. ISBN 0 86180 348 5.
The Met Office London Rd Bracknell Berks RG12 2SZ. UK.
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