Urbanized-MM5 urban-climate
simulations of Houston-Galveston
Bob Bornstein*
R. Balmori and H. Taha
Dept. of Meteor., San Jose State Univ.
San Jose, CA USA
for copy of ppt:
*pblmodel@hotmail.com
presented at
6th ICUC
Göteborg, Sweden
12-16 June 2006
OVERVIEW
• Introduction
– MM5
– Urbanized uMM5
• Houston uMM5 Urban Ozone-Study
– GC/Synoptic influences
– Gulf & Bay breezes
– Urban-climate effects
• Current
• After tree-planting
– Ozone-transport patterns
• Future Work
Urbanization Techniques
• Urbanize subsurface, surface, UCL, SBL, & PBL:
momentum, thermo, & TKE Eqs
• From forest-canopy model (Yamada 1982)
• Veg param replaced with urban (GIS/RS) terms
– Brown and Williams (1998)
– Masson (2000): urban-canyon energy-budget
– Martilli et al. (2001): urban+PBL in TVM
– Dupont et al. (2003): Martilli +
EPA/MM5 (for Ching) UPC
– Taha et al. (2005): LU/LC + UPC  uMM5
From EPA uMM5:
Within Gayno-Seaman
PBL/TKE scheme
Mason + Martilli (by Dupont)
Roughness
approach
Sensible
heat flux
Rn pav Hsens pav LEpav
Drag-Force
approach
Net radiation
Latent
heat flux
Storage
heat flux
Anthropogenic
heat flux
Precipitation
Ts roof
roof
natural
soil
Qwall
Ts pav
Gs pav
Tint
Paved
surface
bare
soil
Surface layer
water
Drainage outside
the system
Infiltration
Drainage
network
Drainage
Root zone layer
Deep soil layer
Diffusion
Martilli et al.
3 new-terms in each prog. PBL eq.
e.g., Momentum ↓
Building: vol
& sfc area
 Advanced urbanization
scheme from Masson
uMM5 inputs as f (x, y)
 land use (38 categories)
 roughness elements
 anthropogenic heat as f (z, t)
 building heights
 paved surface-fractions
 building drag-force coefficients
 building height-to-width, wall-to-plan,
& impervious-area ratios
 building frontal, building plan, & rooftop
area-densities
 ε, cρ, α, etc. of walls and roofs
UCP-inputs (1 km grid) Houston: Ching & Burian (2006)
Building plan
area fraction
Building frontal
area index
Wall-to-Plan
area ratio
Height-to-Width ratio
Brown & Williams: urbanized meso-met model TKE(z)
hc =building top
max urban effect
uMM5 Houston Runs: 22-26 August 2000
• Model configuration
•
•
– 5 Domains: 108, 36, 12, 4, 1 km
– (x,y) grids: 43x53, 55x55, 100x100, 136x151, 133x141
– s-levels: 29 in Ds1-4; 49 in D5; lowest ½ s = 7 m
– 2-way feedback in D1-4
– 96 CPU  4.5 hr for a 24 hr simulation
Physics options
> Grell Cu in D1-2
> ETA or MRF PBL in Ds 1-4
> Gayno-Seaman TKE PBL in D5
> Simple ice
> Urbanization in D-5 > NOAH LSM
> RRTM radiation
Inputs
> NNRP Reanalysis + ADP obs
> Burian LIDAR building-data in D5
> Byun LU/LC modifications
Houston Galveston emissions:
2nd most O3-polluted US city
SHIP CHANNEL
AREA
Houston-Galveston refineries
& chemical plants: along Galveston
Bay ship-channel (Source: Byun 2003)
Episode-day Synoptics: 8/25, 12 UTC (08 DST)
H
700 hPa
Dz = 30 m
H
Surface
Dp = 4 hPa
700 hPa & sfc GC H’s: at weakest (no gradient) over Texas 
meso-scale forcings (sea-breeze & UHI-convergence) dominate
Concurrent NNRP fields at 700 hPa & sfc
H
Dz = 30 m
H
Dp= 2 hPa
NNRP-inputs to MM5 (as IC/BC) captured GC/synoptic
location & strength of NWS-H (on previous slide) 
MM5 can thus do well (Bornstein 2006)
L
D-1
D-2
L
D-3
MM5: episode day, 3 PM
> D–1: reproduced weak
GC p-grad & V
> D-2: new weak coastal-L
> D-3: (well formed) L 
along-shore V
Domain 4 (3 PM) : L off of Houston on high O3 day (25th)
L
 Episode
day
L
uMM5 Domain 5 sfc-winds at 3 PM: 4 successive days
H
C
Episode day:
off-shore L 
along-coast V 
warm-inland 
high O3
25 Aug (episode day) 1500 UTC (same as last slide)
Tx2000
HGA
(gridded)
HGA
Observed winds at
different-scales:
alongshore flow
O3 Interval: 5 ppb (00-16 UTC) & 10 ppb (>16 UTC)
L
C
> 02 UTC: UHI Con
> O3: urban-L +
weak left-over H
H
H
17 UTC: Bay
Breeze + Ship
Channel max
+ Houston
Heat-pump
23
L
H
H 21
16
18
19
H
18 UTC:
urban L
(titration)
L
Note: early
stagnation
17 15
14 UTC
23 UTC Gulf
Breeze & trajectory of O3 max
Urban-effects on night-(non UHI, as wet rural soil) speeds (D-5):
z0 speed-decreases (m/s) over urban-centers
+
+
-
uMM5
-+
+
+
+
V
-
+
Obs
+
Daytime UHI (wet rural soil) 
urban-induced convergence & acceleration
08/24/00
C
C
C
uMM5
Gridded Obs
Along–shore V came from Cold-Core L:
D-3 MM5 vs Obs Temps
H
H
C
18 UTC, Cold-core L (only 1-ob)
& Urban area (blue-dot clump)
seems to retards cold-air penetration!
MM5: produces coastal
cold-core low
D-5 uMM5-MM5 UHI at 8 PM on 21 Aug
H
H
C
Upper
+
L: MM5 UHI = 2.0 K
Upper R: uMM5 UHI = 3.5 K
Lower
L: uMM5-MM5 =
1.5 K stronger UHI
Blob is LU/LC error
8/23 Day UHI: obs vs uMM5 (D-5): 2-m Temps
H
UHI
Cold
UHI
C
Obs: 1 PM
uMM5: 3 PM
Base-case veg (0.1s):
urban-min of current
tree -cover
Modeled increase
tree-cover ( 0.01s):
• urban reforestation
• rural deforestation
Run 14 (urban-reforestation) minus Run 13 (base case):
4 PM 2-m ∆T (K)
> reforested urban-areas are cooler
> surrounding deforested rural-areas are warmer
W’er
C’er
W’er
DUHI(t): Base-case minus Runs 15-18
Urban temp difference between runs
0.4
run14-run13s
run15-run13s
run16-run13s
0.2
run17-run13s
run18-run13s
RURAL
Tdiff (K)
0.0
-0.2
-0.4
URBAN
Max-impact of –0.9 K of
a 3.5 K Noon-UHI, of which
1.5 K was from uMM5
-0.6
-0.8
-1.0
20
0
4
8
12
16
20
0
4
8
LST
• UHI = Temp in Urban-Box minus Temp in Rural-Box
• Runs 15-18: urban re-forestation scenarios
• DUHI = Run-17 UHI minus Run-13 UHI 
max effect, green line
• Reduced UHI  lower max-O3 (not shown) 
EPA emission-reduction credits  $ saved
12
16
Houston Summary
• NNRP captured GC forcing for MM5: weak High
• uMM5 captured the thus strong observed meso effects
–
–
–
–
–
–
•
Weak offshore Low
Ship-Channel (large source area) stagnation
Sequential Bay and Gulf breezes
Urbanization LU/LC characteristics
Houston: UHI & heat-pump
Urban-V patterns
• UHI convergence/acceleration
• Roughness deceleration
– Ozone transport-processes
Urban reforestation
– Decreased max-daytime UHI-values
– Should thus also decrease max-O3 values
FUTURE WORK (1)
• Current uMM5  reduced Houston-UHI 
•
reduced: energy use, biogenics, photolosis 
reduced (?) CAMx/CMAQ O3
EPA emission-reduction credits
Update uMM5 inputs
– Deep-soil BC-temp to eliminate min-T bias
– IC soil-moisture (post rain-storm) to
eliminate max-T bias
– Satellite SST as f(x,y,t)
– Better sea-surface z0 eq.
– Dave Sailor Qa via NSF project
FUTURE WORK (2)
• SJSU/NCAR (Fei Chen) uWRF DTRA proposal
– uMM5 scheme
– Zilitinkevich: diag SBL-eqs for very
stable & unstable conditions
– Freedman: prog k-ε PBL eqs
– 1-way link to: ER canyon-dispersion models
• Downscaled climate-change model-output 
increased NYC (with Columbia/GISS)
> thermal-stress deaths (to NSF)
> thunderstorms  urban floods (to NSF)
> air pollution (to EPA)
ACKNOWLEDGEMENTS
• D. Hitchock & P. Smith, State of TX
• D. Byun, U. of Houston
• J. Nielsen-Gammon, T&M U.
• J. Ching & S. Dupont, US EPA
• S. Stetson, SWS Inc
• S. Burian, U. of Utah
• D. Nowak, US Forest Service
• Funding from: USAID, NSF, DHS, HARC
Houston and uMM5 References
• Balmori, R., 2006: Urbanized MM5 study of urban impacts on an
•
•
•
•
•
•
August 2000 Houston O3 episode. MS Thesis, Dept. of Met., SJSU.
Banta, R. M., et al., 2005: A bad air day in Houston. Bull. Amer. Meteor.
Soc., 86, 657-669.
Byun, D., et al., 2004: Modeling effects of land use/land cover
modifications on the UHI and air quality in Houston, Texas. Tech. Note,
University of Houston, 55 pp.
Dupont, S., et al., 2003: Simulation of meteorological fields within and
above urban and rural canopies with MM5. Tech. Rep., US EPA NOAA,
ARL, NC, 67 pp.
Martilli, A., et al., 2002: An urban surface exchange parameterization
for mesoscale models. Boundary-Layer Meterol., 104, 261-304.
Nielsen-Gammon, J. W., 2004: The surprising dynamics of the Houston
urban sea breeze. Preprints, 84th AMS Conf, Seattle, WA.
Taha, H., et al., 2005: UHI alterations from urban-forest changes in
Houston: uMM5 model of Aug 2000 O3 episode. SJSU Report to HARC.
The End
Any Questions?