Traffic NO2 formula (Traffic NO2 Overlay): Difference between revisions

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The calculations follow the standard rekenmethode 1 (SRM 1).
The calculations follow the standard rekenmethode 1 (SRM 1).


'''Cjm[NO2] = Ca,jm[NO2] + Cb,jm[NO2]'''
<math>Cjm[NO_2] = Ca,jm[NO_2] + Cb,jm[NO_2]</math>


where:
where:
* Cjm[NO2] = annual average concentration [μg/m3]
:<math>Cjm[NO_2]</math> = the calculated annual average concentration [μg/m3],
* Ca,jm[NO2] = annual average background-concentration (default = 0 [μg/m3], can be adjusted via the overlay attributes)
:<math>Ca,jm[NO_2]</math> = the provided annual average background-concentration (default = 0 [μg/m3]). ''Configured using model attribute [[Base no2 (Traffic NO2 Overlay)|BASE_NO2]].''
* Cb,jm[NO2] = annual average traffic contribution to NO2 concentration [μg/m3]
:<math>Cb,jm[NO_2]</math> = the calculated annual average traffic contribution to NO2 concentration [μg/m3].


To compute the annual average traffic contribution to NO2, Cb,jm[NO2] [μg/m3], the following formula from SRM1 is applied:
====Contribution NO2====
To compute the annual average traffic contribution to NO2, <math>Cb,jm[NO_2]</math> [μg/m3], the following formula from SRM1 is applied:


'''Cb,jm[NO2]= fNO2 * Cb,jm[NOx] + (B*Ca,jm[O3]*Cb,jm[NOx]*(1-fNO2))/(Cb,jm[NOx]*(1-Fno2)+K)'''
<math>Cb,jm[NO_2]= fNO_2 \cdot Cb,jm[NO_x] + \frac{B \cdot Ca,jm[O_3] \cdot Cb,jm[NO_x] \cdot (1-fNO_2)}{K + Cb,jm[NO_x] \cdot (1-fNO_2)}</math>


where:
where:
* Cb,jm[NOX] = annual average traffic contribution to NOx concentration [μg/m3]
:<math> Cb,jm[NO_x]</math> = the calculated annual average traffic contribution to NOx concentration [μg/m3],
* Cb,jm[O3] = annual average concentration ozon [μg/m3] (default = 42)
:<math> Ca,jm[O_3]</math> = the provided annual average concentration ozon [μg/m3] (default = 42),
* fNO2 = weighted fraction direct emitted NO2 [-]
:<math> fNO_2</math> = weighted fraction direct emitted NO2 [-],
* B = parameter (default 0.6)
:<math> B</math> = parameter (default 0.6),
* K = parameter for conversion NO to NO2 (default = 100 μg/m3)
:<math> K</math> = parameter for conversion NO to NO2 (default = 100 μg/m3).


====Contribution NOX====
To compute the annual average traffic contribution to NOX, Cb,jm[NOX] [μg/m3], the following formula from SRM1 is applied:
To compute the annual average traffic contribution to NOX, Cb,jm[NOX] [μg/m3], the following formula from SRM1 is applied:


'''Cb,jm[NOx] = Fk * ENOx * θ * Fb * Fmeteo'''
<math>Cb,jm[NO_x] = F_k \cdot ENO_x \cdot \theta \cdot F_b \cdot F_{meteo}</math>


where:
where:
* Fk = calibration factor [-] (default = 0.62]
:<math>F_k</math> = calibration factor [-] (default = 0.62]
* ENOx = emission number NOx [μg/m/s]
:<math>ENO_x</math> = emission number NOx [μg/m/s]
* θ = delution factor [-]
:<math>\theta</math> = dilution factor [-]
* Fb = tree factor (default = XX)
:<math>F_b</math> = tree factor (default = 1)
* Fmeteo = 5/windspeed. Default value for windspeed is 5 m/s
:<math>F_{meteo}</math> = 5/windspeed. Default value for windspeed is 5 m/s


The delution factor, θ, is computed till a distance of 30m with:
The computation of the dilution factor, <math>\theta</math>, is split into two situations. <ref>K. van Velze and J. Wesseling, ''Technische beschrijving van
standaardrekenmethode 1 (SRM-1), paragraph 3.5'', RIVM Briefrapport 2014-0127, https://www.rivm.nl/bibliotheek/rapporten/2014-0127.pdf</ref>


'''θ = a * S^2 + b * S + c'''
For surrounding cells within a distance of 30m:


And from 30-60m (for road-type 1 and 4 only):
<math>\theta = a \cdot S^2 + b \cdot S + c</math>


'''θ = alpha * S^-0.747'''
And for cells within a distance of 30-60m (for road-type 1 only):
 
<math>\theta = \alpha \cdot S^{p}</math>


where:
where:
* S is the calculation distance
: <math>S</math> = the calculation distance
* a, b, c and alpha are parameters depend on road-type:
: <math>a</math> = configurable using model attribute: [[Road1 30m a (Traffic NO2 Overlay)|ROAD1_30M_A]]
: <math>b</math> = configurable using model attribute: [[Road1 30m b (Traffic NO2 Overlay)|ROAD1_30M_B]]
: <math>c</math> = configurable using model attribute: [[Road1 30m c (Traffic NO2 Overlay)|ROAD1_30M_C]]
: <math>\alpha</math> = configurable using model attribute: [[Road1 60m alpha (Traffic NO2 Overlay)|ROAD1_60M_ALPHA]]
: <math>p</math> = configurable using model attribute: [[Road1 60m power (Traffic NO2 Overlay)|ROAD1_60M_POWER]]


[[File:NO2_overlay_02.PNG]]
[[File:NO2_overlay_02.PNG]]


The weighted fraction direct emitted NO2 [-] is computed as:
The weighted fraction of direct emitted NO2 [-] is computed as:


'''fNO2 = ENO2/ENOx'''
<math>fNO_2 = \frac{ENO_2}{ENO_x}</math>


where:
where:
* ENO2 = emission number NOs [μg/m/s]
: <math> ENO_2</math> = emission number NOs [μg/m/s]


====Tree Factor====
The tree factor is calculated as followed:
<math>A_t = \pi \cdot \frac{d^2}{A_c}</math>
<math>F_b = 1 + \frac{t}{ 2 \cdot A_t}</math>
where:
: <math>A_c</math> = Grid cell area in square meters.
: <math>d</math> = Search distance of trees, currently set on 30 meters,
: <math>A_t</math> = Search area measured in amount of cells,
: <math>t</math> = Amount of tree cells within the search distance,
: <math>F_b</math> = Tree factor, value between 1 and 1.5.
Note that this way of calculating the tree factor is more detailed than the suggested calculation of the tree factor: 1, 1.25 or 1.5 and nothing in between.
====Emission numbers====
The emission numbers (E) for both NOx and NO2 are computed as:
The emission numbers (E) for both NOx and NO2 are computed as:


'''E = N * [(1-FS)*((1-(fm+fz+fb))*El + fm * Em + fz * Ez + fb * Eb) + FS * ((1-(fm + fz + fb)) * El,d + Fm * Em,d + fz * Ez,d+fb*Eb,d)]*1000/(24*3600)'''
<math>E_{drive} = (1.0 - j_c) \cdot n_c \cdot E_{c,d} + (1.0 - j_v) \cdot n_v \cdot E_{v,d} + (1.0 - j_t) \cdot n_t \cdot E_{t,d} + (1.0 - j_b ) \cdot n_b \cdot E_{b,d}</math>
 
<math>E_{jam} = j_c \cdot n_c \cdot E_{c,j} + j_v \cdot n_v \cdot E_{v,j} + j_t \cdot n_t \cdot E_{t,j} + j_b \cdot b_t \cdot E_{b,j}</math>
 
<math>E = (E_{drive} + E_{jam} ) \cdot \frac{1000}{(24 \cdot 3600)}</math>


where:
where:
* N = traffic intencity [units per day]
: <math>E</math> = Calculated emission of either NOx or NO2
* fm = fraction vans [-]
: <math>E_{drive}</math> = Calculated emission of driving traffic of either NOx or NO2.
* fz = fraction trucks [-]
: <math>E_{jam}</math> = Calculated emission of jammed traffic of either NOx or NO2.
* fb = fraction buses [-]  
: <math>E_{c,d} </math> = Calculated emission of driving cars, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission car nox (Traffic Overlay)|EMISSION_CAR_NOX]] or [[Emission car no2 (Traffic Overlay)|EMISSION_CAR_NO2]] respectively.''
* El = emission value cars [g/km]
: <math>E_{v,d} </math> = Calculated emission of driving vans, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission van nox (Traffic Overlay)|EMISSION_VAN_NOX]] or [[Emission van no2 (Traffic Overlay)|EMISSION_VAN_NO2]] respectively.''
* Em = emission value vans [g/km]
: <math>E_{t,d} </math> = Calculated emission of driving trucks, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission truck nox (Traffic Overlay)|EMISSION_TRUCK_NOX]] or [[Emission truck no2 (Traffic Overlay)|EMISSION_TRUCK_NO2]] respectively.''
* Ez = emission value trucks [g/km]
: <math>E_{b,d} </math> = Calculated emission of driving buses, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission bus nox (Traffic Overlay)|EMISSION_BUS_NOX]] or [[Emission bus no2 (Traffic Overlay)|EMISSION_BUS_NO2]] respectively.''
* Eb = emission value buses [g/km]
: <math>E_{c,j} </math> = Calculated emission of jammed cars, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission jam car nox (Traffic Overlay)|EMISSION_JAM_CAR_NOX]] or  [[Emission jam car no2 (Traffic Overlay)|EMISSION_JAM_CAR_NO2]] respectively.''
* FS = fraction congested traffic [-]
: <math>E_{v,j} </math> = Calculated emission of jammed vans, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission jam van nox (Traffic Overlay)|EMISSION_JAM_VAN_NOX]] or  [[Emission jam van no2 (Traffic Overlay)|EMISSION_JAM_VAN_NO2]] respectively.''
* E*,d = emission factor per class (cars, vans, trucks or buses) if congested
: <math>E_{t,j} </math> = Calculated emission of jammed trucks, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission jam truck nox (Traffic Overlay)|EMISSION_JAM_TRUCK_NOX]] or  [[Emission jam truck no2 (Traffic Overlay)|EMISSION_JAM_TRUCK_NO2]] respectively.''
: <math>E_{b,j} </math> = Calculated emission of jammed buses, hourly or daily, of either NOx or NO2. ''Configured using Model attribute [[Emission jam bus nox (Traffic Overlay)|EMISSION_JAM_BUS_NOX]] or [[Emission jam bus no2 (Traffic Overlay)|EMISSION_JAM_BUS_NO2]] respectively.''
: <math>n_c</math> = number of car traffic, hourly or daily value. ''Configured in roads using Function Value [[Num cars (Traffic NO2 Overlay)|NUM_CARS]] or as [[Cars_prequel_(Traffic_Overlay)|grid prequel]].''
: <math>n_v</math> = number of van traffic, hourly or daily value. ''Configured in roads using Function Value [[Num vans (Traffic NO2 Overlay)|NUM_VANS]] or as [[Vans_prequel_(Traffic_Overlay)|grid prequel]].''
: <math>n_t</math> = number of truck traffic, hourly or daily value. ''Configured in roads using Function Value [[Num trucks (Traffic NO2 Overlay)|NUM_TRUCKS]] or as [[Trucks_prequel_(Traffic_Overlay)|grid prequel]].''
: <math>n_b</math> = number of bus traffic, hourly or daily value. ''Configured in roads using Function Value [[Num buses (Traffic NO2 Overlay)|NUM_BUSES]] or as [[Buses_prequel_(Traffic_Overlay)|grid prequel]].''
: <math>j_c</math> = fraction of car traffic in traffic jams. ''Configured in roads using Function Value [[Jam factor cars (Traffic NO2 Overlay)| JAM_FACTOR_CARS]].''
: <math>j_v</math> = fraction of van traffic in traffic jams. ''Configured in roads using Function Value [[Jam factor vans (Traffic NO2 Overlay)| JAM_FACTOR_VANS]].''
: <math>j_t</math> = fraction of truck traffic in traffic jams. ''Configured in roads using Function Value [[Jam factor trucks (Traffic NO2 Overlay)| JAM_FACTOR_TRUCKS]].''
: <math>j_b</math> = fraction of bus traffic in traffic jams. ''Configured in roads using Function Value [[Jam factor buses (Traffic NO2 Overlay)| JAM_FACTOR_BUSES]].''


{{article end
{{article end
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|seealso=
|seealso=
* [[Traffic NO2 Overlay]]
* [[Traffic NO2 Overlay]]
|references=
|references=
|references=
   <references>
   <references>

Latest revision as of 12:31, 1 March 2023

The calculations follow the standard rekenmethode 1 (SRM 1).

where:

= the calculated annual average concentration [μg/m3],
= the provided annual average background-concentration (default = 0 [μg/m3]). Configured using model attribute BASE_NO2.
= the calculated annual average traffic contribution to NO2 concentration [μg/m3].

Contribution NO2

To compute the annual average traffic contribution to NO2, [μg/m3], the following formula from SRM1 is applied:

where:

= the calculated annual average traffic contribution to NOx concentration [μg/m3],
= the provided annual average concentration ozon [μg/m3] (default = 42),
= weighted fraction direct emitted NO2 [-],
= parameter (default 0.6),
= parameter for conversion NO to NO2 (default = 100 μg/m3).

Contribution NOX

To compute the annual average traffic contribution to NOX, Cb,jm[NOX] [μg/m3], the following formula from SRM1 is applied:

where:

= calibration factor [-] (default = 0.62]
= emission number NOx [μg/m/s]
= dilution factor [-]
= tree factor (default = 1)
= 5/windspeed. Default value for windspeed is 5 m/s

The computation of the dilution factor, , is split into two situations. [1]

For surrounding cells within a distance of 30m:

And for cells within a distance of 30-60m (for road-type 1 only):

where:

= the calculation distance
= configurable using model attribute: ROAD1_30M_A
= configurable using model attribute: ROAD1_30M_B
= configurable using model attribute: ROAD1_30M_C
= configurable using model attribute: ROAD1_60M_ALPHA
= configurable using model attribute: ROAD1_60M_POWER

NO2 overlay 02.PNG

The weighted fraction of direct emitted NO2 [-] is computed as:

where:

= emission number NOs [μg/m/s]

Tree Factor

The tree factor is calculated as followed:

where:

= Grid cell area in square meters.
= Search distance of trees, currently set on 30 meters,
= Search area measured in amount of cells,
= Amount of tree cells within the search distance,
= Tree factor, value between 1 and 1.5.

Note that this way of calculating the tree factor is more detailed than the suggested calculation of the tree factor: 1, 1.25 or 1.5 and nothing in between.

Emission numbers

The emission numbers (E) for both NOx and NO2 are computed as:

where:

= Calculated emission of either NOx or NO2
= Calculated emission of driving traffic of either NOx or NO2.
= Calculated emission of jammed traffic of either NOx or NO2.
= Calculated emission of driving cars, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_CAR_NOX or EMISSION_CAR_NO2 respectively.
= Calculated emission of driving vans, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_VAN_NOX or EMISSION_VAN_NO2 respectively.
= Calculated emission of driving trucks, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_TRUCK_NOX or EMISSION_TRUCK_NO2 respectively.
= Calculated emission of driving buses, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_BUS_NOX or EMISSION_BUS_NO2 respectively.
= Calculated emission of jammed cars, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_JAM_CAR_NOX or EMISSION_JAM_CAR_NO2 respectively.
= Calculated emission of jammed vans, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_JAM_VAN_NOX or EMISSION_JAM_VAN_NO2 respectively.
= Calculated emission of jammed trucks, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_JAM_TRUCK_NOX or EMISSION_JAM_TRUCK_NO2 respectively.
= Calculated emission of jammed buses, hourly or daily, of either NOx or NO2. Configured using Model attribute EMISSION_JAM_BUS_NOX or EMISSION_JAM_BUS_NO2 respectively.
= number of car traffic, hourly or daily value. Configured in roads using Function Value NUM_CARS or as grid prequel.
= number of van traffic, hourly or daily value. Configured in roads using Function Value NUM_VANS or as grid prequel.
= number of truck traffic, hourly or daily value. Configured in roads using Function Value NUM_TRUCKS or as grid prequel.
= number of bus traffic, hourly or daily value. Configured in roads using Function Value NUM_BUSES or as grid prequel.
= fraction of car traffic in traffic jams. Configured in roads using Function Value JAM_FACTOR_CARS.
= fraction of van traffic in traffic jams. Configured in roads using Function Value JAM_FACTOR_VANS.
= fraction of truck traffic in traffic jams. Configured in roads using Function Value JAM_FACTOR_TRUCKS.
= fraction of bus traffic in traffic jams. Configured in roads using Function Value JAM_FACTOR_BUSES.

Notes

  • If the traffic amount is defined as a single value, that value is used for all defined hours. However, if the amount if an array of values, each of the 24 indexes of that array are assumed to correspond to the hour denoted by those indexes, and as such that specific value from the array is used.
  • The SRM1[2] calculation method is only applicable for urban environments.

See also

References

  1. K. van Velze and J. Wesseling, Technische beschrijving van standaardrekenmethode 1 (SRM-1), paragraph 3.5, RIVM Briefrapport 2014-0127, https://www.rivm.nl/bibliotheek/rapporten/2014-0127.pdf
  2. SRM1 ∙ Regeling beoordeling luchtkwaliteit 2007, Bijlage I ∙ Found at: http://wetten.overheid.nl/BWBR0022817/2013-01-01#Bijlage1 ∙ (last visited: 16-02-2022)