CA1226675A - Chemical event environmental hazard simulator - Google Patents

Abstract

ABSTRACT

A simulator for simulating and predicting the progression of an airborne material such as an aerosol or gas discharged into the atmosphere is disclosed. The simulator includes a display such as a video display monitor, a microcomputer, input devices or the microcomputer and various programs enabling the computer to receive and record meteorological and geographical data and information describing the discharge. A map is shown on the display, along with the discharge site, discharge distribution at selected times after discharge, concentration within the distribution and other information that may be necessary or desirable.

Description

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Field of the Invention The present invention relates to a simulator for simulating the discharge of an airborne material such as an aerosol or a gas into the atmosphere.
Background of the Invention When a hazardous chemical substance is discharged into the atmosphere it is often difficult to predict concentrations, the time of arrival of the substance at a given site and the distribution of the substance by a wind. Of interest to civilian authorities are the prediction of the paths of the hazardous chemical clouds and the anticipated concentrations, so that they can evacuate those people in populated areas where concentrations could be dangerous. The same information is similarly useful for military purposes.
The problem is thus to develop a system to display substance cloud growth and progression in time, overlaying a map.
In order to serve emergency rather than planning purposes, the predictions must be done far more quickly than the real time spread of a cloud of hazardous chemical Sum cry of the Invention According to the present invention, there is provided a simulator for simulating the progression of an airborne material such as an aerosol or gas discharged into the atmosphere, comer lo lung:
- display means for displaying a map of a selected area and the location of a discharge on the map;
data recording means for recording data describing the ,, -~.22667~;

discharge and ambient meteorological conditions;
computing meals for computing from the recorded data the dispersion of the airborne material as a function of time; and means for causing the display means to display on the map the computed dispersion of the airborne material at a selected time after initial discharge of the material.
Preferably, the simulator system is also capable of predicting and displaying the concentration distribution of the substance, the degree of danger at every location on the map, and the time of arrival of the substance at any given point It is also desirable to be able to predict reliably on the basis of a continuing discharge of the substance or a single burst.
Since map data may not be readily available to the simulator, it is also preferred to have a mechanism available for sketching or tracing map data into the simulator for display This can be done using a "digitizing tablet" or a "light pen" on a video display terminal D
Brief Description of the Drawings In the accompanying drawings, which are illustrative of an exemplary embodiment of the present invention:
Figure 1 is a pictorial representation of the hardware used in the exemplary embodiment of the present invention;
Figure 2 is a graph of the normal distribution model used in the exemplary embodiment of the invention;
Figure 3 is a pictorial representation of a cloud from a ground burst;
Figure 4 is a pictorial representation of a cloud from a continuous source;

, ~1.2;26675 Figure 5 is a display header sheet;
Figure 6 is a simulator menu display;
Figure 7 is a text menu display;
Figures 8 to 11 illustrate the use of the simulator in the "draw" mode;
Figure 12 illustrates the Sims k~tor display in the "wind" mode;
Figure 13 through 17 illustrate exemplary displays generated on the simulator in the "simulate mode.
Detailed Description Turning to the drawings, the exemplary embodiment of the simulator, referred to as a "chemical event environmental hazard"
or simply "HAZARD" (TM) simulator is a combination of a microcomputer I with a monitor I a digitizing tablet 16, a light pen 18, a printer 20, IBM (TM) utility and BASIC programs and a "HAZARD" (TM) program that will be described in detail in the following.
The microcomputer 12 is an IBM personal computer with two disc drives, OK memory, an asynchronous communication adapter (SKYE) and a color graphics adapter. The monitor I is an RUB
color monitor. The digitizing tablet 16 is a summagraphics "BIT
PAD ONE". The light pen 18 is an FT-156 light pen from FOG Data Systems. The hardware system is completed with an EPSON, McCauley or MX-80F/T dot matrix printer 20.
The software component of the simulator coats with this hardware to provide:
i) Menu prompted selection of the data input systems (Figure 6);

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ii) A map input system through the digitizing tablet and pen such that the map is generated on the monitor as the pen moves figure 10);
iii) A visual data input system for meteorological data using windowing techniques and a light pen (Figure 12);
iv) The simulation of a hazardous chemical cloud from a continuous source showing relative concentration levels, using selectable time intervals for forward simulation and the use of windowing for screen display simulation conditions (Figures 15 and 17);
and v) The simulation of a hazardous chemical cloud from a single burst (Figure 16).
The exemplary embodiment of the simulator uses certain IBM disc operating system (DOS) version 2.00 programs including DOS systems programs IBMBl0.COM, IBMDOS.COM and COMMAND.COM as well as GRAPHICS.COM and BASICA.COM. All of these IBM programs are proprietary to international business machines (IBM) and can be found on their IBM DOS 2.00 disk.
The exemplified embodiment of the simulator also includes the following programs:
AUTOEXEC.BAT
STAR TEAT
IIAZARD.BAS
EIAZARD.TXT
I've HAZARD.BAS program is the overall operating program for the simulator. It includes map and wind condition input subroutines lZ~667S
as well as a subroutine for generating the required simulation. A
listing of this program is given as Appendix "A". The HAZARD.TXT
program is a subprogram that can be called up to help a user of the simulator. It is, in effect, a bulletin user's manual. The data (text) is not included in the program listing appended to this application as it is not an operating part of this system, but only fixed text that is displayed to an operator for information purposes.
The HAZARD simulator includes the two batch files, "AUTOEXEC.BAT" and START BAT A batch file is a reserved International Business Machines (IBM) "PCDOS Operating System"
(DOS) file name for files that contain DOS commands or the names of other batch files. When a batch file name is typed in, the commands in the batch file are executed as if they were being typed directly in from the keyboard. The AUTOEXEC.BAT and STAT BAT batch files allow the HAZARD simulator to be executed when the computer is turned on with no help from a human operator.
The HAZARD simulator can be started manually by typing "basic"
and the HAZARD file name from the keyboard.
The AUTOEXEC.BAT file for the HAZARD simulator contains the following commands:
a:graphics.com start rem welcome to DOS 2.0 The first line "a:yraphicsOcom" loads a DOS program into memory to allow the contents of a graphics display screen to be printed on a graphics printer when using a color/graphics monitor adapter.
The next line "start" is a batch file that is executed after "graphics.com". This batch file contains the DOS command -~2;26675 "basic" and the HAZARD file name.
Before dealing with the operation of this system, it will be useful to consider the theoretical basis of the plume and cloud spread models employed in this exemplary embodiment. The basic mechanism affecting the mixing and growth of a cloud of gas in the atmosphere is the turbulence of the atmosphere itself.
Although a Cassius substance delivered as a result of an explosive burst will have internal turbulence that promotes cloud growth by entraining air around it, the internal turbulence soon decays and becomes much the same as that in the ambient atmosphere. The nature of this turbulence is described in Lyons, JO. Turbulence, McGraw-ilill, 1975. As a result of the mixing with the atmosphere, the boundaries of the expending cloud have a lower concentration of the discharge substance than that found at the center of the cloud. This variation in the concentration generally follows a Gaussian distribution. By considering the initial mass of hazardous material, lateral variations in downstream concentrations can be calculated for given atmospheric turbulence.
"Plume" and "cloud" models can be used to evaluate the distance over which a cloud (single burst discharge) or plume (continuous discharge) may continue to be hazardous. The distribution of both types and source is dealt with by the simulator.
The probability density function for homogeneous isotropic turbulent flow takes on a Gaussian (normal) distribution Particles governed by gradient diffusion take on a distribution of the following general form (with no time dependence) ~1.2;26675 C2 x2 f = C1 exp (I -2 where Of, C2 are constants. This is also the functional form for diffusion of a point source in a uniform flow.
The Gaussian distribution may be used to model concentration levels in the radial direction of a circular burst.
A cross-section of a typical burst is shown on the left hand side of Figure 2. A plan view is shown in Figure 3. The concentration distribution for the cross-section is r2 C(r) = Coax exp ( 2 )' where C(r) is the concentration at radius r, Coax is the maximum concentration, and r is the radius.
The volume under the burst is therefore r2 V -I or C(r) dry Jo or Coax exp ( - - ) dry = I Coma%

In drawing the circles which border different concentration regions in the burst, the circle which designates the outside of the burst (the area beyond which there is a negligible concentration level) has a finite radius. This radius, ram may be defined arbitrarily as the point where the function C(r) is 0.1~ of the peak concentration at the center of the burst. In normalized coordinates, Max = 3.717.

2~75 The importance of the rrnaX definition is seen when it is needed to simulate diffusion in the burst. Diffusion ox the burst is simulated by increasing Max with time. Mass is conserved by keeping the volume of the burst constant with time.
Based on a new burst size, rmaxr the volume is r 2 r 2 V or Coax exp (I I dry - I Cm (1 - exp (_ o But V is known from the original peak concentration. Thus, the new peak concentration, for larger Max values, will be Max 2 WOW 1 - expel Max )) The rate of increase of Max decreases with increased wind speed.
Once the new peak concentration is determined, the radii corresponding to the desired concentration levels can be found through the relationship (in real coordinates) r I
I., Max ) C(r) _ C exp - -3.717 ' - Max 2 The continuous source model uses segments ox a circle to simulate the boundaries of a turbulent jet. The angle of spread for either side of the jet centerline may be chosen to be in the range of 12 to 25 degrees in order to be close to typical values for a turbulent jet. The trend to smeller angles of spread with higher wind speeds maybe incorporated, The angle of spread of the it jet at the outside boundary and the angles of spread of the intermediate boundaries of concentration ranges are assumed to be invariant with time. The concentration variation from the centerline to the jet boundary is illustrated on the right hand side of Figure 2. A plan view of the dispersion is shown in Figure 4. The distribution is, Gaussian, analogous to that used for the burst The concentration varies with angle, a, from the centerline as follows I/ a 2 O - Coax exp -3-717 where is the half angle of spread of of the jet.
From this application of the deterministic model time required for calculation of various levels of concentrations within the plume can be calculated The shaded areas of the plume shown in Figures 15 and 17 are based on the concentration as a fraction of the centerline concentration. For the single burst model shown in Figure 16, the concentrations are based on volume mixing rates. More sophisticated models can be used and speed of _ g _ Sue calculation can be considerably increased by using a more sophisticated compiler. What is isnportant is that the microcomputer calculates and displays results in a way that is meaningful to the operations personnel. Color bands for survival time or level of hazard end cloud fronts representing the anticipated arrival time of the threat as well as population centers exposed to the threat are meaningful factors. These are displayed immediately on the screen and no numbers need to be processed by the observer to comprehend the magnitude of the event.
In the following, certain notation conventions are used to distinguish between the text of the specification and the following:
- screen messages - keys pressed by the user - words to be typed in by the user To operate the exemplary embodiment of the simulator, Ices must be pressed to choose courses of action. key on the keyboard is referred to by its keyboard symbol or name surrounded by brackets. The following are examples:
Escape Sue ~Esc>
Number 1 I
Fly key fly>
The following keys are referred to by their names:
Space bar lacy space bar>
Shift key shift>
Enter key venter>

~2~675 ennui reference is made to a rnessaye printed on the monitor, the message is printed in bolt text. For example:
Press Space biro when more than a one key must be typed in to respond to a prompt, the response will be in bold text surrounded by double quotation marks. For example: "used".
U _ the Simulator There are three basic steps to using the simulator:
l) generate a topographical map;
0 2) select wind speed and direction;

3) obtain a graphical simulation of a hazardous chemical event.
The map is venerated by drawing selected geographical and cartographical features, for example bodies of water and contour lines using the dicJitizing tablet A grid with loo moire increments can also be placed on the map. Population indicators can be superimposed on the map using the digitizing tablet as a pointing device.
The wind direction is set using the licJht pen on a wind O compass. The wind speed is set using the light pen on a bar graph.
In the graphical simulation, the time that will elapse between each plot of the dispersion and the source type (discrete puff or continuous jet) is chosen using the keyboard. The source location is placed on the map using the light pen. when the source position has been selected, the options available are running the simulation forward or backward in time, restarting the simulation, or exiting from the simulation.

- ~Z~6Ç~75 On starting the simulator, the header display of Figure 5 appears on the monitor screen with the prompt preys space bar to kitten. Pressing the space bar briny up the main menu.
Figure 6 shows the monitor image itch contains the main menu on the upper right side of the monitor. Menus will always appear in this region of the screen The selection of a menu choice is made using the function keys <F1> to I , and the ~Esc~ key.
0 EXIT Command In general, the EXIT command allows escape or exit from the current command or menu to the next higher command or menu.
With the header display (Err 5), pressing ~Esc~ will cause exit from the HAZARD simulator operation to the IBM disk operating system. In the DRAW command, pressing ~Esc> return the simulator to the main menu. when the light pen is used, an EXIT is made by pressing the light pen on the screen beside EXIT in the menu (i.e.
the ~Esc> key will not work).
HOPE Command '0 The HELP command provides a brief set of instructions on how to use the HAZARD simulator.
Pressing <F1> activates the HELP command and displays a screen of text explaining one feature of the simulator. The screen title is printed on the upper left corner of the screen.
The bottom line of the screen (Figure 7) displays the prompt:
Press space bar> to continue - ~Esc> to EXIT
Pressing the space bar will display the next screen of text and <Esc> will return the simulator to the main menu. The YELP instructions serve as an internal user's manual ~.2~667S

DRAW Command The DRAW command allows the production of a map on the monitor screen using a digitizing tablet.
Pressing OF will bring up the DRAW menu on tune right and display the map on the left side of the screen (Figure 8).
The cursor symbol "+" indicates the symbol that is used to show the current position ox the pen on the digitizing tablet. If a command in the DRAW menu needs more input, a second menu is displayed on the lower right side of the screen. The map is automatically saved when ON exit from DRAW and will reappear ON
reentry to the DRAW command.
C AR Command The CLEAR command allows erasure ox the entire map. The erasure is irreversible and cannot be undone. The CLEAR command returns directly to the DRAW menu.
The CLEAR command is activated by pressing I
GRID Command -The GRID command places a one thousand moire grid on the map (Figure 9). The map is then one kilometer square with one hundred moire divisions. The GRID command displays the prompt RID in the second menu area while it is busy and returns directly to the DRAW menu.
LINE Command The LINE command allows the drawing of lines, such as contour lines, on the map. These appear on the zap as dashed lines.
Pressing <F3> activates the LINE command and opens a second menu (Figure 10) prompting the use of Esc to EXIT from the LINE command and return to the DRAW menu. The "I" cursor on the map indicates the current position of the pen on the digitizing tablet. Moving the pen across the tablet will move the cursor across the map. The pen has a switch that is activated by pressing lightly down on the pen. This switch is used to activate line drawing. Drawing a map line involves the following steps:
1) Placing the pen or cursor where the line is to start.
2) Pressing) down on the pen and tracing the line on the digitizing tablet.
3) Lifting the pen to stop drawing the line.
PEOPLE COMMAND
The PEOPLE command allows the placement of population symbols on the map to indicate areas inhabited by people. The population symbol appears on the map as a "happy face" (Figure 11~ .
Pressing ~F4> activates the PEOPLE command end opens a second menu prompting the use of ~Esc> to EXIT from the PEOPLE
command and return to the DREW menu. Like the LINE command, the "I" cursor indicates the current position of the pen on the digitiæiny tablet. Placing a population symbol on the map involves these steps:
1) Placing the pen or cursor on the map where the symbol is to appear 2) Briefly pressing the pen down to place the symbol on the map and lifting the pen If the pen is held down to long, more than one symbol will be drawn and the simulation graphics may be obscured.

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PRINT Command The PRINT command makes a printed paper copy of the map using the dot matrix printer Pressing showoff end protozoic>
together activates the PRINT commend.
Before using the PRINT command, mace sure the printer is turned on, connected to the computer, and the paper is set to the top of a page. I-E the printer is not ready to print, the computer will remain inactive for approximately twenty seconds, after which you can continue. After printing a copy of the screen, the Lo simulator will return to the DRAY menu.
LOAD COMMAND

-The LOAD command loads a map into the computer from a file on floppy disk Pressing ~F5> starts the LOAD command, which prompts you to enter an eight character name of the file where the map is stored:
Enter ILLUME -I ?
Exit from this command is by pressing venter> .
The following is an example of the typical steps that I are used to load a map from a DOS file 1) Press <F5~ to activate the LOAD command.
2) Type in the 1 to 8 character name of the file containing the map, frame for example, and press entry .
(vote: only maps saved using the SAVE command described below may be loaded using this command.) If the file is found, the message:
Loading fnameO~P
will appear as the map is loaded. If the file is not found, the prompt:

, J.. I ' ~t;675 fnam~.~AP not found, Press essay is displayed. On pressing <Esc> the prompt:
Enter PHYLUM ->
will reappear.
SAVE Command The SAVE command saves a map as a file on a floppy disk.
Pressing EYE activates the SAVE command, which prompts the entry of a one to eight character name under which the current map image is to be stored. Exit from the SAVE command is by pressing entry .
A map is saved using the following steps:
1) Pressing <F6~ to activate the SAVE command.
2) Typing in the 1 to 8 character name chosen for the map file, frame for example, and pressing Enter The massage:
Saving fnarne~MAP
appears while the file is being created.
WIND Command I The WIND command allows the insertion of the wind speed and direction using the light pen.
Pressing <F3> activates the WIND command and displays the current wind speed and direction on the screen, as shown in Figure 12. The left section of the screen contains a compass which indicates wind direction and a bar graph which indicates wind speed. The right side of the screen contains the WIND menu.
The menu choice is EXIT to end the wind data selection and return to the main menu, The EXIT command is executed by pressing the light pen in the white box beside Exit .. . . ..

Jo 2~6~75 The wind direction is chosen by pressing the light pen in the ring around the compass The wind will blow towards the point at which the pen is pressed. For example, by pressing the light pen down in the ring just below the letter "N", a south wind, bearing approximately 3303 miss, will be stored. The accuracy of the FT-156 light pen on the IBM Color Monitor is limited. Therefore, precise selection of some wind ankles is not possible in this embodiment.
The wind speed is chosen by pressing down with the light pen in the box above the desired wind speed. The length of the colored bar in the box indicates the current wind speed. In this embodiment the wind speed is selectable only in increments of approximately 1.33 km/h because of the accuracy of the light pen.
SIMS Command The SUE command runs the simulator Pressing ~F4> activates the SIMS command, whereupon the simulator uses the map and wind data created using the DRAW
and WIND commands to run a graphical representation of the dispersion of a chemical agent. If the SIMS command is executed before creating a map with the DRAW command, the message:
Map does not exist' appears briefly on the bottom line of the screen. The main menu remains and is active again after the message above is gone.
The first screen that appears in the SIMS command is shown in Figure 13. The map is redrawn and the simulation information is displayed on the right side of the screen. The wind direction and speed and map range are given to aid in selecting an appropriate time step and source location. Also s Shown is a legend of the color patterns which represent the three ranges of concentrations: DANGER, WARNING, and SEE.
Before the simulation can proceed, the time step and the source type and its location must be selected.
The time step is the increment in time which the simulation will progress. us shown in Figure 13, the prompt that first appears at the bottom of the screen is:
Time step is 1.0 Lange 7 ok? no since the default time step is one minute. Pressing my> accepts 0 the time step. If on> is pressed, the following prompt is produced:
Enter time step twin):
to which the operator responds using the number keys in the top row of the keyboard and the ~.~ (period) key. The maximum allowable time step is 1000~0 minutes. The desired time step, 1.2 for example, is keyed in and venter> is pressed. The prompt for verification will appear again as:
Time step is I minor ox? (y/n) Pressing > accepts this step, while pressing on> rejects it 'O There are two options available, should a mistake occur in keying in the time step. The first is to backspace over the mistaken Iceystrokes using the left arrow cursor movement key, found on the right of the keyboard, and type over them with the correct values.
The second option is to press venter> , respond on> to the new verification prompt, and retype the value.
There is a choice of two types of chemical sources in this simulator The first is an aerosol generator type (A) which is a continuous source of chemical agent. The second is a ground ....

~26~75 burst chemical simulator type (GBCS) which is a single discrete puff of chemical agent Roy default source type is AGO After the time step has been accepted, the prompt on the bottom line of the screen will be:
Source type is Go ok? (yo-yo Pressing < I> accepts this source type. Pressing on> will produce the prompt:
Source type is GBCS, ok? no Pressing my> will accept GBCS as the source type. Pressing on>
will switch back to source type AGO Switching between the two types continues until my> is pressed.
Once the source type is selected, the following prompt appears on the bottom line of the screen:
-> Set source with light pen <-To set the source location press the light pen down on the map where the source is to he placed.
After the source location has been set, the SIMS MENU
for control of the simulator appears in the upper right corner of the screen as shown in Figure 14. Also, the bottom line of the screen prompts with:
Enter menu choice with light pen A SIMS MINI] command is activated by pressing the light pen in one of the boxes beside this colnmarld name. The four light pen-activated choices in the SIMS MENU are:
l) FORWARD - run the simulation forward one time step;
BACKWARD - run the simulation backward one time step;
3) RESTIMULATE - restart the simulation at the time step prompt;

4) EXIT - exit simulation and return to the main menu.

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The Prolate command may also be chosen at any time to produce a printed hard copy of the screen contents.
The FORWARD Command .
The FORWARD command runs the simulation forward one time step and displays the boundaries of the source-contaminated regions. This command is activated by pressing the light pen in the box beside FORWARD. For the GBCS source, all time steps up to the current one are shown so that the user can trace the path of the single puff. When the maximum of 9 (nine) time steps is lo reached, the message:
Max no ox time frames!
will appear in the bottom line of the screen. At this point, another command must be chosen Figures 15 and 16 illustrate, for A and GBC~ sources respectively, the result of placing the source in the upper left courier of the map and choosing FORWARD twice. The boundaries are shown for an elapsed time of I minutes, a wind speed of 23.3 km/h, and a wind direction of 5656 miss.
The BACKWARD Command The BACKWARD command runs the simulation baclcward one time step. This command is activated by pressing the light pen in the box beside BACKWARD If the elapsed time is at 0.0 seconds, the time will remain at zero for any further choice of the BACKWARD command.
Figure 17 displays the A source boundaries one time step backward from the results shown in figure 15.
The R~SIM~LTE Command The RESTIMULATE command halts the current simulation and ~6~i75 allows restarting of the simulation, beginning at the time step prompt. This command is activated by pressing the light pen in the box beside RESTIMULATE. Thus, using the same wind speed and direction as before, changes can be made in the time step, the source type, or the source location.
The EXIT Command The EXIT command stops the simulation an returns to the main menu as shown in Figure 5. This command is activated by pressing the light pen in the box beside EXIT.
PRINT _ Monday The PRINT command makes a printed paper copy of the map using the dot matrix printer. This is activated by pressing iffy protozoic> together. After printing a copy of the screen, the simulator will return to the SIMS menu.
The chemical agent plume dispersion models used in this exemplary simulator are not intended to produce precise results which exactly match a practical situation. The models used to display the plume and cloud boundaries are very simple in order to speed up the display process. The quick display is important since the purpose o-f the simulation is to enable rapid prediction and reaction. The detailed calculations required for more realistic plume models are possible with more powerful computer hardware and software. Thus, in other embodiments where more detailed predictions are required, models may be used that account for ground contours, building concentrations and other geographical features. The exemplary embodiment is also limited to a 100 meter map grid. In other embodiments, the map scale will be variable to provide more flexibility. It is also to be understood that various modifications in the hardware system are also possible, for example using a portable rugged micro computer end fewer manual input systems. Meteorological conditions, including wind, humidity, precipitation etc. may be entered using a direct input from appropriate instruments.

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Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A simulator for simulating the progression of an airborne material such as an aerosol or gas discharged into the atmosphere, comprising:
display means for displaying a map of a selected area and the location of a discharge on the map;
data recording means for recording data describing the discharge and ambient meteorological conditions;
computing means for computing from the recorded data the dispersion of the airborne material as a function of time; and means for causing the display means to display on the map the computed dispersion of the airborne material at a selected time after initial discharge of the material.

2. A simulator according to claim 1, including:
means for computing from the recorded data the distribution of the airborne material concentration as a function of time; and means for causing the display means to display the concentration distribution at said selected time on the map.

3. A simulator according to Claim 2 wherein the data recording means include means for recording data describing a continuing discharge of the material into the atmosphere.

4. A simulator according to Claim 2, wherein the data recording means include means for recording data describing a burst discharge of the material into the atmosphere.

5. A simulator according to claim 1, including:
means for computing from the recorded data a value representing degrees of danger from the material as a function of time and location; and means for causing the display means to display the distribution of the degrees of danger at said selected time on the map

6. A simulator according to Claim 1, including means for computing from the recorded data the time of arrival of the material at a selected location in the selected area and means for causing the display means to display the selected location on the map

7. A simulator according to Claim 1, including means for causing the display means to display on the map locations that are sensitive to the airborne material.

8. A simulator according to Claim 1, wherein the display means simultaneously display the map the dispersion of the airborne material and selected recorded data and computed information.

9. A simulator according to Claim 1, including a digitizing tablet input device connected to the simulator through which data may be supplied to the simulator to be recorded.