ADMS QUARTERLY LOG 2nd EDITION JULY 1996
Published Newsletter Index
Contents
Introduction
ADMS Plus GIS!
New Email Address
Helpdesk Calls
Release of ADMS 2.1
Code Changes
Error Messages to the Screen
Using Surfer
User Suggestions
User Questions
Notes
New Limits and Guidelines
Summary
Introduction
This second log includes a handy reference sheet of revised limits and guidelines , the latest upgrade news, a record of model adaptations and a log of user enquiries and suggestions received over the last quarter.
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ADMS Plus GIS!
We are glad to welcome Imperial College, Offshore Environmental Services and Stanger Science and Environment to the list of users of the ADMS-2 plus GIS system. It allows the user to produce attractive contour plots on real map data for presentations and reports. Other benefits include:
- Choice of map data e.g.: satellite images; CAD drawings; Ordnance Survey Raster maps
- Geographical analysis of model results to determine environmental impact
- Attractive dynamically linked graphics, charts, tables and report layouts.
Simply click on the image to view a full-size version of the GIS system.
PRICE: ADMS GIS Interface Link £700 + VAT
ArcView GIS Software £1095 + VAT
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New Email Address
CERC now have a new address in a new domain. You can now reach us at cerc.co.uk. Mail for personnel at CERC should be addressed to xxxx@cerc.co.uk. For example, helpdesk queries can be sent to anne@cerc.co.uk. However we can still receive mail at our Compuserve address but will only be able to do so for a couple more months so please make a note of the new address now!
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Helpdesk Calls
The number of calls logged in the last quarter was 64.
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Release of ADMS-2.1
The upgrade v2.1 will be released to all our customers during September. Features include the capability to model complex terrain with statistical met. data and fluctuations of concentration.
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Code Changes
| Description of Bug | Date Logged | Date Fixed/ Due to be Fixed |
|---|
Radioactivity and puffs with volume sources was not completing runs with
more than one line of met data | 6/96 | 2.1 |
| Percentiles not working with line area & volume sources | 6/96 | 2.1 |
| When use Grids and Specified points, the points give zero values | 23/7/96 | 2.1 |
| Coastline module and 10 degree wind sector not giving correct answers | 23/7/96 | 2.1 |
| Volume sources not recognizing the height of the source | 7/96 | 2.1 |
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Error Messages to Screen
1 - ERROR: DIVIDE BY ZERO - WHEN RUNNING HILLS
Response: This message can occur for a number of reasons. The user should check that:
(a) the source position, the terrain grid and the output grid are all in the same coordinates e.g. National Grid or Relative to Datum (0,0).
(b) the output grid is contained within the terrain grid
(c) the source position is not too near the edge of the terrain grid.
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Using Surfer
1 - PLOTTING PERCENTILES OF FLUCTUATIONS OF CONCENTRATION IN SURFER
(i) Launch Surfer.
(ii) In Surfer choose Grid, Data.
|
Click to view screenshot
|
(iii) Delete the filenames highlighted in dark blue
and type filename.Q01 in the appropriate directory.
(iv) Click OK and select ASCII DATA from the selection available. Click OK. |
Click to view screenshot |
(v) In "Data Columns" under "Z:", choose D from the list. Click OK. This means that the contour plot will be of the lowest percentile in the next column of the *.Q01 file. E.g., if in ADMS you choose to calculate the 95th, 88th and 80th percentiles, column D will be of the 80th percentile. If you select E for the Z: entry, the plot will be of the 88th percentile. If you select F, then the plot will be of the 95th percentile and so on.
Note: this is the opposite to percentiles of mean concentration files *.P01, which are written out with the highest percentile in column D.
Click to view screenshot |
(vi) Three "bleeps" will be heard when Surfer has completed the new plot. To view it, select File, New, Plot.
(vii) Select Map, Contour, OK, OK and the chosen percentile is plotted. It does not have any heading however but text is easily added by using the "T" add text tool in Surfer. |
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User Suggestions
1 - AT PRESENT THERE IS NO OPTION BUT TO LOCATE THE CENTRE OF A POLAR GRID AT (0,0). THIS WOULD BE USEFUL SO THAT THE OS UTILITY COULD BE USED WITH DATA IN NATIONAL GRID COORDINATES.
Response: At present, there is no plan to rectify this but if more users think that this would be a valuable addition to the model then please let us know. Currently, most users employ a Cartesian grid when using the complex terrain utility.
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User Questions
1 - HOW CAN THE MAXIMUM 8-HOURLY CONCENTRATION AT EACH GRID POINT BE CALCULATED?
Response: Set the averaging time in the Setup screen to 8 hours and use 10 years of statistical data to calculate the 100th percentile. This gives the maximum concentration experienced at each grid point. Concentric or almost concentric circles can be expected for the 100th percentile contour plot.
2 - IS THERE A FACILITY TO MODEL TIME VARYING EMISSIONS IN ADMS-2?
Response: There is no direct facility to model time varying emissions directly in ADMS-2 but this will be introduced in ADMS-3. However, if the user is modelling a puff release, it is possible to change the emission rate during release periods of up to 24 hours. For example, the user could define a number of identical sources at the same X,Y location. For each source, a total emission could be specified with a unique start time and release duration. The table below details this further:
| Source | Pollutant | Total Release (units/s) | Start Time (s) | Release Duration (s) |
|---|
| Source 1 | SO2 | 1000 | 0 | 5400 |
| Source 2 | SO2 | 856 | 5400 | 21600 |
| Source 3 | SO2 | 1690 | 21600 | 30600 |
| Source 4 | SO2 | 2089 | 30600 | 39600 |
| Source 5 | SO2 | 768>39600 | 72000 |
The user would then run the group "All Sources" to calculate the concentration downstream at a series of timesteps due to the changing emission rates from the same source over a period of 0-20 hours (72000 seconds).
3 - IF THE WASHOUT COEFFICIENT IS NOT KNOWN WHAT SHOULD BE ENTERED IN THE POLLUTANTS SUBSCREEN?
Response: If you do not want to calculate wet deposition then enter a value of zero. If any other value is entered and wet deposition is not checked in the output screen, the model will still calculate the values but not write those values to output files. Therefore run time is increased unnecessarily.
If you do want to calculate wet deposition but do not know the washout coefficient, a reasonable estimate would be to use the default values of washout coefficients A and B. Provided that you have precipitation information in met. file, these values will be used to estimate the total washout coefficient based on the precipitation parameter P. The equation is of the form:
Washout Coefficient = APB
If you select these coefficients but fail to include the parameter P in the met. file, then wet deposition will not be calculated.
4 - WHAT IS THE SIGNIFICANCE OF CHOOSING REACTIVE, NON-REACTIVE OR INERT AS THE NATURE OF THE GAS IN THE POLLUTANTS SUBSCREEN?
Response: The option to enter this data becomes available when the Deposition velocity is not known.
Since deposition velocity is not known, the model must calculate it. It does so by calculating the resistance of the pollutant which is the reciprocal of the deposition velocity, 1/vd. The total resistance is made up three resistance values which are:
r' - the aerodynamic resistance
rb - the sub-layer resistance and
rs - the surface resistance.
r' and rb are dependent on meteorology and subsequently, the calculated value of u*. rs is dependent on the nature of gas you specify with a general level for each category. Typical values for a range of gases are shown in the table below. If this option is chosen, the value of vd calculated by the model will be shown in the log file (*.LO1).
| Type | Definition | Examples | rs/sm-1 |
|---|
| Reactive Gas |
Gases expected to undergo significant chemical reaction with the surface. |
SO2, O3, NOx, I2, Cl2, HF | 100 |
| Unreactive Gas |
Gases not undergoing significant chemical reaction with the surface. |
CO2, CH3, I | 1000 |
| Inert Gas |
Noble Gases | He, Ne, Ar, Kr, Xe, Rn | Infinite |
5 - SHOULD ONE BE ABLE TO USE THE AUTOMATIC X-Y PLOTTING FACILITY FOR POINTS CLOSE TO THE SOURCE?
Response: The I, J and K files that are written to produce X-Y plots automatically do not write out values for points less than 10m from the source. This is to avoid very high maximums close to the source making values even slightly further downstream unreadable on the graph. However, the values are written out to the *.C01 file so that contour plots can be produced and X-Y plots can be made in Excel (or similar spreadsheet).
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Notes
1 - OS DIGITAL TERRAIN DATA - Users should purchase OS data in .ntf format
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New Limits and Guidelines
The EU, WHO and DoE long and short term guidelines and limits for SO2, NO2, CO and Ozone are summarised in the tables that follow. These are used in assessing the significance of stack emissions.
Note: Users referring to this table are advised to check if revisions have been made since July 1996.
| | SO2 | NO2 | CO | Ozone | PM10 |
|---|
| Hourly Average Concentration ug/m3 | | | | | |
| EU (Vegetation Protection) | - | - | - | 200 | |
EU (Population Warning)| - | - | - | 360 | |
| WHO | 325 | 400 | 29mg/m3 | 150-200 | |
| DoE (very good) | 160 | 95 | - | 100 | |
| DoE (very poor) | 1064 | 573 | - | 360 | |
| | | | | |
|
| 98th Percentile of Hourly Average ug/m3 | | | | | |
| EPAQS | | 200 | | |
50 |
| EU Limit | | 135 | | | |
| EU Guide Value | | | | | |
| | | | | |
|
| 24 Hourly Average ug/m3 | | | | | |
| EU Guide Value | 100-150 | - | - | - | |
| WHO | 93 | 153 | n/a | 66 | |
| | | | | | |
| 98th Percentile of Hourly Average ug/m3 | | | | | |
| EU Limit | 350* | | | | |
* The EU air quality standards state that SO2 values for the 98th percentile of daily values should not exceed 350ug/m3 provided smoke concentrations are less than 150ug/m3.
| | SO2 | NO2 | CO | Ozone | Benzene | 1,3-Butadiene |
|---|
| Annual Average |
| | | | | |
| WHO Limit | 50 | 30 | | | | |
| EU Guide Value | 40-60 | 50 | | | | |
| EPAQS | | | | | 5ppb
| 1ppb |
| | | | | | | |
| Running 8 Hour Mean | | | | |
| EPAQS | | | 10ppm | 50ppm |
| | | | | |
| 15 Minute Average | | | | |
| EPAQS | 100ppb | | | |
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Summary
Please keep us informed of any improvements you would like to see in the model or user guide and topics you would like to be discussed in future editions of ADMS NEWS
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