Download Philadelphia case

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MODELING AT
NEIGHBORHOOD SCALE
Sylvain Dupont and Jason Ching
E-mail: [email protected]
Collaborators: Tanya Otte and Avraham Lacser
U.S. Environmental Protection Agency
Research Triangle Park, NC
University
Corporation for
Atmospheric
Research
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Objective: modeling air-quality for estimating
human exposure to air pollution in urban area.
 Modeling at neighborhood scale: development of an Urban
Canopy Parameterization (UCP) inside MM5 for CMAQ.
 Estimating the sub-grid-scale
concentration fields.
variability
in
the
pollutant
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Outline
Definition of neighborhood scale
Urban Canopy Parameterization (UCP)
# General scheme
# Dynamic, thermal, humidity and TKE components
Preliminary results: Philadelphia case
# MM5 results
# CMAQ results
Conclusions and Perspectives
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Neighborhood scale
Interaction between meso and local scales.
Meso scale
Neighborhood scale
1 km.
Local scale
Roughness Sub-Layer
Rural
Rural
Urban
Neighborhood scale
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The details of the whole urban canopy can not be represented:
 Parameterization of the urban surface effects.
Meso scale
Neighborhood scale
1 km.
Local scale
Roughness Sub-Layer
Rural
Rural
Urban
Neighborhood scale
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Majority of pollutants are emitted inside the roughness sub-layer:
 Necessity to have a good representation of meteorological fields.
Meso scale
Neighborhood scale
1 km.
Local scale
Roughness Sub-Layer
Rural
Rural
Urban
Neighborhood scale
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The ground conditions used by mesoscale models are not satisfactory
at neighborhood scale:  Drag-force approach.
Meso scale
Neighborhood scale
1 km.
Local scale
Roughness Sub-Layer
Rural
Rural
Urban
I Modèle de sol urbain SM2-U
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Drag-Force approach
Meso scale
Neighborhood scale
1 km.
Roughness Sub-Layer
Rural
Rural
Urban
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Urban Canopy parameterization
 The UCP is introduced inside the Gayno-Seaman PBL model.
 Complete the drag-force approach introduced by Lacser & Otte in
MM5 following the work of Martilli (2002).
 Extend the drag-force approach to all roughness elements inside the
canopy: buildings and vegetation.
 Introduce the detail soil model SM2-U considering both rural and
urban surfaces.
Urban canopy parameterization
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SM2-U
Rural
Rural
Urban
Roof
Paved surface
Natural surface
Water
Bare soil
Superficial layer
Superficial layer
2nd soil layer
3th soil layer
Urban canopy parameterization
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Net radiation
New version
of the UCP
Sensible
heat flux
Latente
heat flux
Anthropogenic
Storage
heat flux
heat flux
Precipitations
ktop
Ts3Dmoy(k)
LE3Dmoy(k)
Hsens3Dmoy(k)
Superficial soil layer
Rn can Hsens can LEcan
Ts roof
Draining
network
Draining
Infiltration
2nd soil layer
3td soil layer
Qwall
Ts can
Gs can
Tint
Draining outside
the systeme
Return towards
equilibium
Urban canopy parameterization
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Urban morphology
The knowledge of the vertical and horizontal distribution of the
different surface types is necessary.
Roof area
density
Building
plan area
density
z
z
1
1
Building Vegetation
frontal area
area
density
density
z
z
1
Vegetation
plan area
density
z
1
Urban canopy parameterization
Dynamic component
Momentum equation = forcing terms
(modification of vertical turbulent transport term)
+ momentum sources due to horizontal and vertical building
surface
+ momentum sources due to vegetation
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Urban canopy parameterization
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Thermal components
Net radiation: solar,
atmospheric, and earth
radiations
Hsens i
LE
Gs i
Sensible
heat flux
Latent heat
flux
Storage
heat flux
Roof
Paved Surface
Rn i
Anthropogenic
heat flux
Natural soil
Water
Bare soil
Superficial layer
Qanth i
Superficial layer
Heat equation = forcing terms
(modification of vertical turbulent transport term)
+ heat sources from surfaces + anthropogenic heat sources
Urban canopy parameterization
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Effects of the canopy thickness
 Modification of paved surface temperature equation
# Heat capacity of the wall
# Heat exchange between through the
R n can
Hsens can LEcan
Ts roof
buildings
# Radiative trapping: introduction of an
effective albedo parameterization
deduced from Masson (2000).
 Extinction of the radiation through the canopy
Qwall
Ts can
Tint
G can
Urban canopy parameterization
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Humidity components
Evapotranspiration
Precipitations
Natural soil
Roof
Bare soil
Paved surface
Superficial layer
Superficial layer
Draining
network
Infiltration
Draining
Water draining
outside the
system
2nd soil layer
Water
Return
towards
equilibrium
3th soil layer
Humidity equation= forcing terms
(modification of vertical turbulent transport term)
+ humidity sources from surfaces + anthropogenic humidity sources
Urban canopy parameterization
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TKE components
TKE equation= forcing terms
(modification of vertical turbulent transport and dissipation terms)
+ TKE sources due to horizontal and vertical building surface
+ TKE sources due to vegetation
+ TKE sources due to sensible heat fluxes
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Summary of MM5 versions
 Roughness approach
SLAB (SOILMOD=0)
GS PBL (IBLTYP=6)
SM2-U (SOILMOD=1)
MM5v3.5
LSM (SOILMOD=0)
PX PBL (IBLTYP=7)
 Drag approach
SM2-U (SOILMOD=1)
GS PBL (IBLTYP=6) + SLAB + Lacser & Otte UCP
MM5v3.5
GS PBL (IBLTYP=6) + SM2-U (3D) + new UCP
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Preliminary results: Philadelphia case
 14 July 1995 (sunny day).
 MM5 has been run in a one-way nested
configuration: 108, 36, 12, 4 and 1.33 km
horizontal grid spacing.
 UCP uses only for the 1.33 km domain.
 Turbulent scheme model: Gayno-Seaman PBL
with the turbulent length scale of Bougeault and
Lacarrere (1989).
Philadelphia case
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1.33 km domain
112x112x40 grid points
4 km domain
85x88x30 grid points
Philadelphia case
For the 1.33 km domain:
 7 urban categories have
been defined following
Ellefsen (1990-91).
 23-category (USGS)
vegetation categories.
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Philadelphia case
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Mixing height and wind vectors at 50 m AGL
a) the standard version of MM5 using GS PBL
b) GS PBL including TLSP (B-L,89)
Without UCP (nocan)
a)
b)
Mixing Height at 2 p.m.
Mixing Height at 2 p.m.
(in meter)
(in meter)
1200
1080
960
840
720
600
480
360
240
120
0
X
80
60
40
20
0
0
20
40
60
Y
80
100
5 m.s-1
100
1200
1080
960
840
720
600
480
360
240
120
0
80
X
100
60
40
20
0
0
20
40
60
Y
80
100
5 m.s-1
Philadelphia case
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Vertical profiles in central Philadelphia,
Ratios: a) local u*, and b) TKE to local u* max at 2 p.m.
c) potential temperature at 6 a.m.
Solid line (can), dash line (nocan); Roof percentage bottom right
7
0
2 p.m.
6
5
4
3
2
1
0
0
0.5
1
1.5
u*(local)/u*(max)
2
b)
Roof percentage
75
50
25
100
8
0
100
400
2 p.m.
7
350
6
5
4
3
2
1
0
0
c)
Height above the ground (m)
100
8
Roof percentage
75
50
25
Height above the ground / average building height
Height above the ground / average building height
a)
Roof percentage
75
50
25
0
6 a.m.
300
250
200
150
100
50
1
2
3
4
2
tke/(u*(max))
5
6
0
292
294
296
298
300
potential temperature (K)
Philadelphia case
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6 a.m.
6 a.m.
(in meter)
100
400
360
320
280
240
200
160
120
80
40
0
60
40
Can simulations
0
0
20
40
60
Y
80
(in meter)
1200
1080
960
840
720
600
480
360
240
120
0
X
60
40
20
20
40
60
Y
80
20
40
2000
1800
1600
1400
1200
1000
800
600
400
200
0
80
60
40
20
40
60
Y
80
80
100
5 m.s
-1
(in K)
304
303
302
301
300
299
298
80
60
40
20
0
0
20
40
60
Y
80
100
5 m.s-1
6 p.m.
(in meter)
20
60
Y
100
100
100
X
0
6 p.m.
c)
0
0
0
2 p.m.
80
Right: air temperature
and wind vectors at 50 m
20
100
100
0
0
40
2 p.m.
b)
Left: mixing height
60
X
Meteorological
fields
20
298
297
296
295
294
80
100
(in K)
100
308
307
306
305
304
303
302
301
300
80
X
X
80
(in K)
100
X
a)
60
40
20
0
0
20
40
60
Y
80
100
5 m.s
-1
Philadelphia case
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6 a.m.
6 a.m.
(in meter)
100
250
200
150
100
50
0
-50
-100
-150
-200
-250
40
20
0
0
(can-nocan) simulations
20
40
60
Y
80
(in meter)
250
200
150
100
50
0
-50
-100
-150
-200
-250
X
60
40
20
0
20
40
60
Y
80
20
40
250
200
150
100
50
0
-50
-100
-150
-200
-250
80
60
40
20
20
40
60
Y
80
80
100
0.2 m.s-1
(in K)
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
80
60
40
20
0
0
20
40
60
Y
80
100
0.2 m.s-1
6 p.m.
(in meter)
0
60
Y
100
100
100
X
0
6 p.m.
c)
0
0
2 p.m.
80
0
20
100
100
Right: air temperature
and wind vectors at 50 m
40
2 p.m.
b)
Left: mixing height
60
X
Difference fields
60
4
3.5
3
2.5
2
1.5
1
0.5
0
-0.5
-1
80
100
(in K)
100
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
80
X
X
80
(in K)
100
X
a)
60
40
20
0
0
20
40
60
Y
80
100
0.2 m.s-1
Philadelphia case
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CMAQ Results
 MM5 v 3.5 (w/UCP).
 CB-IV mechanism.
 Turbulent scheme from the G-S PBL scheme.
 CMAQ computational domain and grid structure based on MM5
domains:
# 21 layer gridding for 36, 12, and 4 km simulations
# 31 layer gridding for 1.33 km runs with UCP
 Emission processing using SMOKE
# Near surface emissions distributed into lowest 10 vertical layers for
1.33 km grid simulations
Philadelphia case
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Normalized Difference with and without BL89 (nocan) ( 2pm EDT)
(a) CO; (b) HCHO; © NOx; (d) O3
a
c
b
d
Philadelphia case
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Parameter Sensitivity Case Study
July 14, 1995
Grid size 1.33 km
(Pcan – P nocan) /P can
Philadelphia case
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Normalized Difference for CO
(6 a.m. local)
Philadelphia case
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Normalized Difference
(6 p.m. local)
NOx
Ozone
Philadelphia case
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Normalized Difference
for Fine Particle Number
(Left: 6 a.m. Right 6 p.m.)
Philadelphia case
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Multi-scale Simulations
36 -12 -4 -1.33 km grid sizes
July 14, 1995
(6 p.m. local)
Philadelphia case
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CO
Philadelphia case
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NOx
Philadelphia case
35/41
Ozone
Philadelphia case
36/41
Fine Particle Number (x10 9)
Philadelphia case
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Sulfate (mg/m3)
Philadelphia case
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Ammonium
3
(mg/m )
Philadelphia case
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Elemental Carbon
3
(mg/m )
Philadelphia case
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Aldehydes (with UCP)
HCHO
CH3CHO
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Neighborhood-Scale Modeling
Summary Points
 UCP introduced into MM5
# Modified turbulence length scale parameterization in GS-PBL
model: Suppresses undesired undulations
#Improved Dispersion parameters: Mixing heights, U*, stability, …
 Air quality fields
# Sensitivity to introduction of UCP
# Spatial pattern details resolved at N-S
# Resolution requirements differ for different pollutants
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Project Status, Future plans
• Testing and refining UCPs in MM5 and CMAQ
• Develop PDFs for sub-grid variability for different
parent grid resolutions
• Work-in-Progress: Prototype study
– Preliminary results for Philadelphia
• Advanced N-S modeling for Houston, Texas
– Detailed urban morphology data base