x  down wind  
y  lateral (sideways)  
z  vertical (height) 
1  downwind distance X to pool (m) 
2  vol%. (dry) gas fraction CAV at y = z = 0 
3  vertical dispersion coefficient SZ (m) 
4  crosswind dispersion coefficient SY (m) 
5  halfwidth b of middle part of crosswind concentration profile (m) 
6  temperature TMP (C) 
7  effective cloud halfwidth B_{eff} (m) 
8  effective cloud height H_{eff} (m) 
9  cloud halfwidth (normal definition) (m) 
TITLE  The title of the current problem to be run with POSTHS. 
At most 50 alphanumeric characters.  
Optional, no default. 
OUT2  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
XRANGE2  Range of values for down wind distance x. 
Optional, defaults as given below.  
Following the XRANGE2 keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for x (m). 10^{6} <= #1 <=10^{}6. (default is 0.0) #2 maximum value for x (m). 10^{6} <= #2 <=10^{}6. (default 1000.0) #3 step size for x (m). 10^{6} #3 10^{}6. (default 10.0). 

HORAX2  Horizontal axis parameter type (). 
1 <= HORAX2 <= 9.  
Mandatory.  
VERAX2  Vertical axis parameter type (). 
1 <= VERAX2 <= 9.  
Mandatory. 
OUTB  At most 40 alphanumeric characters. 
Mandatory.  
XRANGEB  Range of values for x. 
Optional, defaults as given below.  
Following the XRANGEB keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for x (m). 10^{6} <= #1 <=10^{}6. (default 0.0) #2 maximum value for x (m). 10^{6}<= #2 <= 10^{}6. (default 1000.0) #3 step size for x (m). 10^{6} <= #3 <= 10^{}6. (default 100.0) 

YRANGEB  Range of values for y. 
Optional, defaults as given below.  
Following the YRANGEB keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for y (m). 10^{6} <= #1 <= 10^{}6. (default 0.0). #2 maximum value for y (m). 10^{6} <= #2 <= 10^{}6. (default 20.0). #3 step size for y (m). 10^{6} <= #3 <=10^{}6. (default 10.0). 

Optional, defaults as given below.  
ZRANGEB  Range of values for z. 
Following the ZRANGEB keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for z (m). 0.0 <= #1 <= 10^{6}. (default 0.0). #2 maximum value for z (m). 0.0 <= #2 <= 10^{6}. (default 10.0). #3 step size for z (m). 10^{6} <= #3 <= 10^{}6. (default 5.0). 
OUTC  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
RANGEC  Range of contour values. Optional, defaults as given below. 
Following the RANGEC keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum contour value (%). 10^{6} <= #1 <= 100.0. (default set from actual model file data). #2 maximum contour value (%). 10^{6} <= #2 <= 100.0. (default set from actual model file data). Limited to 90% of maximum concentration in the model file for the requested plane. #3 number of contours (). 1<= #3<= 6. (default 6). 

XC  Constant value x for contour plane yz (m). 
10^{6} XC 10^{}6.  
Optional, no default.  
YC  Constant value y for contour plane xz (m). 
10^{6} YC 10^{}6.  
Optional, if none of XC, YC or ZC are specified, default is taken to be YC = 0.  
ZC  Constant value z for contour plane xy (m). 
0.0 ZC 10^{6}.  
Optional, no default. 
OUTSX  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
XRANGESX  Range of values for x. 
Optional, defaults as given below.  
Following the XRANGESX keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for x (m). 10^{6} <= #1<= 10^{}6. (default 0.0). #2 maximum value for x (m). 10^{6} <= #2 <= 10^{}6. (default 1000.0). #3 step size for x (m). 10^{6} <= #3 <= 10^{}6. (default 10.0). 
OUTXYZ  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
XYZ  Coordinate position which may occur up to 20 times, but which must occur at least once. 
Following the XYZ keyword, a block of 3 parameters (#1 to #3) must be specified: #1 xcoordinate (m). 10^{6} <= #1<= 10^{}6. No default. #2 ycoordinate (m). 10^{6} <= #2<= 10^{}6. No default. #3 zcoordinate (m). 0.0 <= #3 <= 10^{6}. No default. 
DURATION  Duration of release (s). 
1 DURATION 3600.  
Optional, must be specified if ERRORFUN block is used..  
AVTIMC  Averaging time for concentrations (s). 
0 AVTIMC 3600.  
Optional, default is the value used in the corresponding HEGADASS run.  
Should not normally be set by the user, value will be read from the model data file 'casename.HSM'. Any value set in POSTHS will override the value used in the corresponding HEGADASS run.  
If the user has specified DELTA in the HEGADASS DISP input block then AVTIMC in HEGADASS has no value and AVTIMC must be specified here.  
AVTIMC is only ised in HEGADASS for the finite duration correction. 
x  down wind  
y  lateral (sideways)  
z  vertical (height) 
1  vol% (dry) gas fraction CAV at y = z = 0 
2  vertical dispersion coefficient SZ (m) 
3  crosswind dispersion coefficient SY (m) 
4  halfwidth b of middle part of crosswind concentration profile (m) 
5  effective cloud halfwidth B_{eff} (m) 
6  effective cloud height H_{eff} (m) 
7  concentration at y = z = 0 (kg/m^{3}) 
TITLE  The title of the current problem to be run with POSTHT. 
At most 50 alphanumeric characters.  
Optional, no default. 
OUTDX  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TIMEDX  Required time for output (s). 
0 <= TIMEDX <= 3600.  
(default set to first time in model file data).  
TYPEDX  Dispersion data type (). 
1 <= TYPEDX <= 7.  
Mandatory.  
XRANGEDX  Range of values for x. 
Optional.  
Following the XRANGEDX keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for x (m). 10^{6} <= #1 <= 10^{}6. (default 0.0). #2 maximum value for x (m). 10^{6} <= #2<= 10^{}6. (default 1000.0). #3 step size for x (m). 10^{6} <= #3 <= 10^{}6. (default 10.0). 
OUTB  At most 40 alphanumeric characters. 
Mandatory.  
TIMEB  Required time for output (s). 
0 <= TIMEB <= 3600.  
(default set to first output time in model file data).  
XRANGEB  Range of values for x. 
Optional.  
Following the XRANGEB keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for x (m). 10^{6} <= #1 <= 10^{}6. (default 0.0). #2 maximum value for x (m). 10^{6} <= #2 <= 10^{}6. (default 1000.0). #3 step size for x (m). 10^{6} <= #3 <= 10^{}6. (default 100.0). 

YRANGEB  Range of values for y. 
Optional.  
Following the YRANGEB keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for y (m). 10^{6} <= #1 <= 10^{}6. (default 0.0). #2 maximum value for y (m). 10^{6} <= #2<= 10^{}6. (default 20.0). #3 step size for y (m). 10^{6} <= #3 <= 10^{}6. (default 10.0). 

ZRANGEB  Range of values for z. 
Optional.  
Following the ZRANGEB keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for z (m). 0.0 <= #1 <= 10^{6}. (default 0.0). #2 maximum value for z (m). 0.0 <= #2 <= 10^{6}. (default 10.0). #3 step size for z (m). 10^{6} <= #3<= 10^{}6. (default 5.0). 
OUTC  Filename of the required output file 'filename.ext' (full pathname if required).  
At most 40 alphanumeric characters.  
Mandatory.  
TIMEC  Required time for output (s).  
0 <= TIMEC <= 3600.  
(default set to first time in model file data).  
RANGEC  Range of contour values.  
Optional. Following the RANGEC keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum contour value (%). 10^{6} <=#1<= 100.0. (default set from actual model file data). #2 maximum contour value (%). 10^{6} <=#2<= 100.0. (default set from actual model file data). #3 number of contours (). 1 <= #3 <= 6. (default 6). 

XC  Constant value x for contour plane yz (m).  
10^{6} <=XC <= 10^{}6.  
Optional, no default.  
YC  Constant value y for contour plane xz (m).  
10^{6} <=YC<= 10^{}6.  
Optional.  
If none of XC, YC or ZC are specified, default taken as y=0.  
ZC  Constant value z for contour plane xy (m).  
0.0 <=ZC <= 10^{6}.  
Optional, no default. 
OUTSX  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TIMESX  Required time for output (s). 
0 <= TIMESX <= 3600.  
(default set to first time in model file data).  
XRANGESX  Range of values for x. 
Optional.  
Following the XRANGESX keyword, a block of 3 parameters (#1 to #3) must be specified: #1minimum value for x (m). 10^{6} <= #1 <= 10^{}6. (default 0.0). #2maximum value for x (m). 10^{}6 <= #2 <=10^{}6. (default 1000.0). #3 step size for x (m). 10^{}6 <= #3 <= 10^{}6. (default 10.0). 
OUTXYZ  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TIMEXYZ  Required time for output (s). 
0 <=TIMEXYZ <= 3600.  
(default set to first time in model file data).  
XYZ  Coordinate position which may occur up to 20 times, but which must occur at least once. 
Mandatory.  
Following the XYZ keyword, a block of 3 parameters (#1 to #3) must be specified: #1 xcoordinate (m). 10^{6} <= #1 <= 10^{}6. No default. #2 ycoordinate (m). 10^{6} <= #2 <= 10^{}6. No default. #3 zcoordinate (m). 0.0 <= #3 <= 10^{6}. No default. 
OUTDT  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TRANGEDT  Range of values for time. 
Optional.  
Following the TRANGEDT keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for time (s). 0 <= #1 <= 3600. (default set to first time in model file data). #2 maximum value for time (s). 0 <= #2 <= 3600. (default 3600.0). #3 step size for time (s). 10^{6} <= #3<= 3600. (default 10.0). 

TYPEDT  Dispersion data type (). 
1 <=TYPEDT <= 7.  
Mandatory.  
XVALDT  Value for x (m). 
10^{6} <=XVALDT<= 10^{}6.  
Mandatory. 
OUTXYZT  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TRXYZT  Range of values for time. 
Optional.  
Following the TRXYZT keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for time (s). 0 <= #1 <= 3600. (default set to first time in model file data). #2 maximum value for time (s). 0 <= #2 <= 3600. (default 3600.0). #3 step size for time (s). 10^{6} <=#3 <=3600. (default 10.0). 

XYZT  Coordinate position which may occur up to 20 times, but which must occur at least once. 
Mandatory.  
Following the XYZT keyword, a block of 3 parameters (#1 to #3) must be specified: #1 xcoordinate (m). 10^{6} <=#1 <=10^{}6. No default. #2 ycoordinate (m). 10^{6} <=#2 <=10^{}6. No default. #3 zcoordinate (m). 0.0 <= #3 <= 10^{6}. No default. 
OUTD  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TIMED  Required time for output (s). 
0 <= TIMED <= 3600.  
Mandatory.  
XYZD  Coordinate position which may occur up to 20 times, but which must occur at least once. 
Mandatory.  
Following the XYZD keyword, a block of 3 parameters (#1 to #3) must be specified: #1 xcoordinate (m). 10^{6} <= #1 <= 10^{}6. No default. #2 ycoordinate (m). 10^{6} <= #2 <=10^{}6. No default. #3 zcoordinate (m). 0.0 <= #3 <= 10^{6}. No default. 
OUTE  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TMINE  Minimum time for output (s). 
0 <=TMINE<= 3600.  
Optional (default set to first output time in model file data).  
TMAXE  Maximum time for output (s). 
0 <= TMAXE <= 3600.  
Optional (default 3600.0). 
OUTMX  Filename of the required output file 'filename.ext' (full pathname if required). 
At most 40 alphanumeric characters.  
Mandatory.  
TYPEMX  Dispersion data type (). 
1 <= TYPEMX <= 7.  
Mandatory.  
XRANGEMX  Range of values for x. 
Optional.  
Following the XRANGEMX keyword, a block of 3 parameters (#1 to #3) must be specified: #1 minimum value for x (m). 10^{6} <= #1 <= 10^{}6. (default 0.0). #2 maximum value for x (m). 10^{6} <= #2 <= 10^{}6. (default 1000.0). #3 step size for x (m). 10^{6} <= #3 <=10^{}6. (default 10.0). 
AVTIMC  Averaging time for concentrations (s). 
0 <= AVTIMC <= 3600.  
Optional, default is the value used in the corresponding HEGADAST run.  
Should not normally be set by the user, value will be read from the model data file 'casename.HTM'. Any value set in POSTHT will override the value used in the corresponding HEGADAST run.  
If the user has specified DELTA in the HEGADAST DISP input block then AVTIMC in HEGADAST has no value and AVTIMC must be specified here.  
NOTE AVTIMC in POSTHT is (only) used for timeaveraging (or timesmoothing) of calculated concentrations c(t) to obtain (average) concentrations c_{av}(t) where c_{av}(t) is 1/AVTIMC multiplied by the integral, from tAVTIMC/2 to t+AVTIMC/2, of c(Tau) dTAu. 