Overview%20of%20urban%20models%20for%20simulation%20of%20urban%20climate,%20weather,%20and%20air%20quality

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Overview of urban models for simulation of urban
climate, weather, and air quality
Prof. Bob Bornstein Dept. of Meteorology San Jose
State University San Jose, CA USA pblmodel_at_hotmail
.com presented at MEETING OF EXPERT TEAM ON
URBAN CLIMATOLOGY WMO, GENEVA, 23 MAY 2005
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PROPOSED OUTLINE

• HISTORY
• CURRENT STATUS
• NEW FORMULATIONS
• PROBLEM AREAS
• APPLICATIONS
• WEATHER
• CLIMATE
• AIR QUALITY
• OUTLOOK
• FURTHER ADVANCEMENTS
• LOCAL APPLICATIONS

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HUMAN-HEALTH IMPACTS OF URBAN CLIMATEselling
points

• UHI ? THERMAL STRESS
• PRECIP ENHANCEMENT RUNOFF? FLOODS
• CHANGED DISPERSION PATTERNS FOR
• POLLUTION EPISODES
• EMERGENCY RESPONSE

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NEW URBAN TEMPS CAUSES THAT MUST BE MODELED

• GRASS/SOIL ? CONCRETE/BUILDINGS ?
• NEW SOIL MOISTURE CONTENT ?
• NEW THERMAL INERTIA ?
• ALTERED SFC HEAT MOSITURE FLUXES
• FUEL CONSUMPTION ?
• ATM POLLUTION, HEAT, AND MOISTURE
• BUILDINGS (LOW SKY-VIEW FACTORS)
• ATM POLLUTION?
• ALTERED (SOLAR IR) RADIATIVE FLUXES

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URBAN WX ELEMENTSbattles b/t conflicting
effects that must be modeled

• TEMP PRECIP increased or decreased
• VISIBILTITY decreased
• WIND SPEED increased or decreased
• WIND DIRECTION con- divergence
• TURBULENCE increased (mechanical thermal)
• PBL NIGHT STABILITY neutral
• FRONTS (synoptic sea breeze) slowed
• THUNDERSTORMS triggered or split

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New Urbanization Techniques

• Urbanize surface, SBL, PBL (momentum,
• thermo, TKE) Eqs
• Allows prediction within UCL
• From veg-canopy model (Yamada 1982)
• Veg param replaced with urban (GIS/RS) ones
• Brown and Williams 1998
• Masson 2000
• Sievers 2001
• Martilli et al. 2001 (in TVM)
• Dupont et al. 2003 (in MM5)

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? From Masson (2000)
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Sfc Energy Models SiB has new vegy-paramters
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Within Gayno-Seaman PBL/TKE scheme
From EPA uMM5 Mason Martilli (by Dupont)
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_________
______
3 new terms in each prog equation
? Advanced urbanization scheme from Masson (2000)
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New GIS/RS inputs for uMM5 as f (x, y, z)

• land use (38 categories)
• roughness elements
• anthropogenic heat as f (t)
• vegetation and building heights
• paved-surface fractions
• drag-force coefficients for buildings
  vegetation
• building height-to-width, wall-plan,
  impervious-
• area ratios
• building frontal, building plan, and rooftop
  area-
• densities
• wall and roof e, c?, a, etc.
• vegetation canopies, root zones, stomatal
  resistances

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From S. Stetson Houston zo data
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Performance by physics
sound waves PBL schemes take most CPU in both
urban/PBL scheme in uMM5 takes almost 50 of all
time
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Urbanized meso-met model results
urban effect
_________________
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Martilli/EPFL results
Urbanization ? day nite on same line ?
stability effects not important
Non-urban
urban
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KEY IDEA IDEAL MESO-MET ATM-MODEL CAPTURES ALL
BC FORCINGS IN CORRECT ORDER

• O3 EPISODES OCCUR ON A GIVEN DAY
• NOT B/C TOPO, EMISSIONS, OR SFC MESO-FORCING
  (EXCEPT FOR FOG) CHANGES
• BUT DUE TO CHANGES IN UPPER-LEVEL SYNOPTIC WX
  PATTERNS, WHICH
• COME FROM AN EXTERNAL MODEL WHICH
• ALTER MESO SFC-FORCINGS (i.e., TOPO, LAND/SEA,
  URBAN) VIA MESO-TEMP AND THUS WIND
• MUST THUS EVALUATE ABOVE FACTORS
• UPPER LEVEL SYN WX Patterns pressure then
  winds
• TOPOGRAPHY (via grid spacing) channeling of wind
• MESO SFC temperature then winds

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SCOS Temp (full domain)
RUN 1
RUN 5
03-Aug-1997
04-Aug-1997
05-Aug-1997
06-Aug-1997
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NYC (a) z0 vs UHI effect in z-section (upper L)
(b) Sea breeze obs (upper R), (b) no
barrier (lower L), with barrier (lower R)
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ATLANTA UHI-INITIATED DAYTIME STORM (0BS) T V
(UPPER L) CONV (UPPER R) PRECIP (LOWER L)
CLOUDS (LOWER R)
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MM5 simulation of previous storm UHI (upper L),
CONV (UPPER R) w (lower L), PRECIP (LOWER R)
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uMM5 for Houston O3 SIP

• GIS/RS gridded urban sfc parameters
• uMM5 reforestation ?
• reduced daytime max UHI ?
• CMAQ O3 model uMM5 output ?
• reduced emissions photolysis rates ?
• lower O3 ? emission-reduction credits ?
• big savings of

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Coastal Cold-Core L on episode day at 3 PM for
Domains 1-3
L
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Domain 4 (3 PM) Note cold-core L off of Houston
on O3 day (25th)
? Episode day
L
L
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Urbanized Domain 5 near-sfc 3 PM winds on 4
successive days

• Episode
• day

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Domain 5 end of daytime UHI (8 PM 21 Aug)

• Upper L MM5
• Upper R uMM5
• Lower L uMM5-MM5
• uMM5? 1.5 K warmer (stronger UHI)
• Blob is LU/LC error

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Domain 5 end of night UHI 9 AM 22 Aug

• Upper L MM5
• Upper R uMM5
• Lower L MM5-uMM5
• uMM5? 1.5 K cooler (weaker UHI)

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Explanation of uMM5 UHI UCI

• Wet soil TI gt urban TI gt dry soil TI
• Urban area surrounded by wet soil ?
• Daytime UHI (as urban area warms faster than
  soil)
• Nighttime UCI (as urban area cools faster than
  soil)
• Reverse true with dry rural soil
• Current results thus consistent with wet rural
  soil (as expected) around Houston, as uMM5
  produced daytime warming nighttime cooling of
  Houston

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Base-case (current) vegetation cover (urban min)
Modeled increases in vegetation cover (urban
max) values are 0.1 of those above
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Soil moisture increase for Run 12 (entire area,
left) and Run 13 (urban area only, right)
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Run 12 (urban-max reforestation) minus Run 10
(base case) near-sfc ?T at 4 PM shows
thatreforested central urban-area cools
surrounding deforested rural-areas warm
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CMAQ ozone modeling for Houston SIP 6
tree-planting scenarios ? reduced UHIs (right)
in urban-box 1 (left) for run 17? lower
max-ozone ? emission-reduction credits from EPA
Max impact
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EMERGENCY RESPONSEgt INFO REQUIRED (IN
20-30 MIN)gt NEED URBAN-CANYON METgt QUESTIONS
TO BE ANSWERED

• WHAT IT IS
• WHAT IS ITS CONCENTRATION
• WHERE IS ITS SOURCE
• WHERE WILL IT GO
• WHAT ARE ITS FUTURE
• CONCENTRATION PATTERNS

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REAL-TIME FORECASTS REQUIRE

• FAST CPU
• GOOD LARGE-SCALE WX-MODEL RESULTS
• GOOD URBAN-CANYON MODULES IN MESO-MODELS
• GOOD MESOSCALE (SFC UPPER AIR) OBS NETWORKS
• REAL-TIME COMMUNICATIONS
• SIMPLE MODELS FOR EMERGENCY RESPONSE

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NEIGHBORHOOD-SCALE RESEARCH MODELS

• TYPES
• EPA WIND TUNNEL
• NOAA CFD (FLUENT)
• INDOOR-OUTDOOR EXCHANGE (LBNL)
• USES
• SCIENTIFIC UNDERSTANDING
• DEVELOP PARAMETERIZATIONS FOR RAPID RESPONSE
  MODELS

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QUIC Simulation dd 215 deg
MSG
wind vectors at 5 m height
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LBNL Group
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FUTURE TRENDS

• Meso-met forecasts for
• Regional air quality
• Urban met
• Better urban meso-met models
• Faster computers
• Better parameterizations
• Smaller grids
• Urban meso-scale models linked with
• CFD urban canyon scale models
• Downscaling of global-change model results

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The EndQuestions?