Will Pendergrass

NOAA/ARL/ATDD

OAR Senior Research Council Meeting

Oak Ridge, TN

August 18-19, 2010

Boundary–Layer Dispersion

Urban Meteorology

04/18/23 Air Resources Laboratory

04/18/23 Air Resources Laboratory

The DCNet Urban Testbed

04/18/23 Air Resources Laboratory

Why Urban Micrometeorology?•The lowest layers of the Atmosphere are in direct contact with where people work, play, live. Hence, we need to understand atmospheric flow behavior over various terrain, especially over populated regions!

•Dispersion forecast models mainly rely on parameterizations and relations derived from research over “ideal” (i.e., rural, flat, homogeneous) terrain. We need to generate improved parameterizations to help models perform better over complex urban areas!

•Improving parameterizations means collecting measurements!

0 2000 4000 6000

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mg

/m**

3

IDLH = 30 mg/m**3

PEL = 3 mg/m**3

5 degrees15 degrees

25 degrees

DCNet is a NOAA dispersion forecasting program, intended to (a) to determine how best to make use of local data in order to derive an acceptably accurate product and (b) to provide DC with the best possible dispersion forecasting system.

DCNet

04/18/23 Air Resources Laboratory

Current

DCNet Stations

2 km5 km

04/18/23 Air Resources Laboratory

04/18/23 Air Resources Laboratory

Urban Complications

04/18/23 Air Resources Laboratory

DCNet Enhanced NAM12 plume and trajectory

DCNet Non-Enhanced NAM12 plume and trajectory

Do UrbanObservations

Make aDifference?

HYSPLIT4 Simulations

04/18/23 Air Resources Laboratory

>0 - 1

>1 - 3

>3 - 5

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>10 - 15

0 % 5 % 1 0 % 1 5 %

0 % 5 % 1 0 % 1 5 %

0 % 5 % 1 0 % 1 5 %

0 % 5 % 1 0 % 1 5 %

Urban Climatology

04/18/23 Air Resources Laboratory

Q = K ↓- K ↑ +L ↓ - L ↑ = QH + QE + ∆QS

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Month

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-1

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1

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mp

erat

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nce

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)

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Mean Temperature DifferencesUrban - Rural

Sensible Heat Flux

Urban Heat Island

04/18/23 Air Resources Laboratory

Urban Velocity Profiles

Observed Profiles

Modeled

Apparent Flow Regime

04/18/23 Air Resources Laboratory

04/18/23 Air Resources Laboratory

2010 CalNexus Science Questions Transport and Meteorology

Goal: Improved Urban Canopy Layer

Parameterizations

• How best can we characterize and model air flow over coastal waters and the complex terrain of California?

•What are the major deficiencies in the representation of chemistry and meteorology in research and operational models and how can models be improved through the collection of additional measurements? What physical and chemical processes are not captured well by available models? Is there an optimum grid resolution to capture all of the relevant physical and chemical processes that occur?

04/18/23 Air Resources Laboratory

Urban Canopy ModelStudy Focus

Urban State Variables

"URBAN ROOF SKIN TEMPERATURE" "K" "URBAN WALL SKIN TEMPERATURE" "K" "URBAN ROAD SKIN TEMPERATURE" "K" "URBAN CANOPY TEMPERATURE" "K" "URBAN CANOPY WIND SPEED" "K" "URBAN CANOPY HUMIDITY" "kg kg{-1}" "M-O LENGTH ABOVE URBAN ROOF" "dimensionless" "M-O LENGTH ABOVE URBAN WALL" "dimensionless" "M-O LENGTH ABOVE URBAN ROAD" "dimensionless" "M-O LENGTH ABOVE URBAN CANOPY" "dimensionless" "ROOF LAYER TEMPERATURE" "K" "WALL LAYER TEMPERATURE" "K" "ROAD LAYER TEMPERATURE" "K" "SENSIBLE HEAT FLUX FROM URBAN SFC" "W m{-2}" "LATENT HEAT FLUX FROM URBAN SFC" "W m{-2}" "GROUND HEAT FLUX INTO URBAN" "W m{-2}" "NET RADIATION ON URBAN SFC" "W m{-2}" "COS of SOLAR ZENITH ANGLE" "dimensionless" "SOLAR HOUR ANGLE" "dimensionless" "SOLAR DECLINATION" "dimensionless"

04/18/23 Air Resources Laboratory

Calnex PasadenaMonitoring Station

Keck Laboratories

CalNex: Pasadena

04/18/23 Air Resources Laboratory

Estimating sensibleheat flux from

surface temperatures

04/18/23 Air Resources Laboratory

Urban friction coefficient: Cf

Skimming Flow

CalNex: Pasadena DCNet: Federal Triangle

04/18/23 Air Resources Laboratory

• Meteorological data transferred to community ftp site• Abstract submitted for AGU special session• High frequency spectral data in review• Complete energy balance components in review

CalNex Status

04/18/23 Air Resources Laboratory

•Conduct research over other types of terrain such as suburban regions, coastal cities, etc…

•Assess changes in turbulent flow along transects from suburban to urban to suburban.

•Assess spatial variability of vertical profiles of mean winds and turbulence; mobile remote sensing.

•Observe the budget of TKE: Does the oft-used “local dissipation” assumption for turbulence (rates of mechanical and buoyant production equals rate of viscous dissipation) hold above the urban canopy?

Urban MeteorologyFuture Directions