NYC METEOROLOGY: NYC METEOROLOGY:

MODELSMODELSby

BOB BORNSTEIN Dept of Meteorology, SJSU

pblmodel@hotmail.comfor

DHS/UDS MeetingEML, NYCJune 2004

OUTLINEOUTLINE

URBAN MESOMODEL PROBLEM AREAS CURRENT STATUS

– URBAN WEATHER/CLIMATE– MESOMODELS– MODEL URBANIZATION

PROBLEM AREAS– MESOMODELS– MODELURBANIZATION

OUTLOOK

SJSU STUDIESSJSU STUDIES

URBMET/TVM: – NYC, SFBA, PHOENIX, SAO PAULO, FOS

MM5: – SFBA, ATLANTA, LA, HOUSTON

WRF (PROPOSED): – HOUSTON

URBAN MESOMODEL URBAN MESOMODEL PROBLEMSPROBLEMS

LINKAGE OF URBAN MODELING SCALES – Canyon (microscale model)– Roughness sub-layer [u*(z)] vs SBL (neighborhood

model)– Urban BL (mesomodel)

BUILDING-HEIGHT VARIATION what is lower boundary?

INHOMOGENEOUS SFC TYPE thermal, rad, and, roughness param are f(x,y)

RAD FLUX DIV DUE TO AEROSOLS interactive met and air quality models elev urban inversions & actinic flux

LOWER MODELLOWER MODELBOUNDARY SURFACE?BOUNDARY SURFACE?

GROUND SURFACECOMBO OF GROUND, WALL, AND

ROOF SURFACESROUGHNESS HEIGHTROUGHNESS SUBLAYER TOP

MESO-MODEL URBANIZATIONMESO-MODEL URBANIZATIONSIMPLE (NON-POROUS FLOWS)

– no T & V within URBAN CANYONS– Taha: OHM model for heat storage term– Bornstein: building-barrier effects

COMPLEX (POROUS FLOWS): from

Yamada’s forest canopy formulation– Brown and Williams: roof-drag effects– Mason: TEB urban canyon-energy effects– Martilli: wall-drag effects– Dupont: Martilli + forests + GIS data

1. Subgrid Variability1. Subgrid Variability

A. Predominant

B. Average Parameters (Kimura 1991)

concretep cc

cTT

cccc CGW

00

5.03.02.0

WATER 20%GRASS 30%

CONCRETE 50%

Barrier EffectBarrier Effect

Building Block Approach

Add grid-averaged urban-building topography height to natural topography

(Bornstein et al. 1993; Panayiotou 1995)

Reproduces: diffluence around city; blocking; daytime upslope convergent and nighttime downslope divergent flows

Does not reproduce: street canyon flows, which requires building-scale model

Advanced Urbanization Advanced Urbanization TechniquesTechniques

General Idea: Modify surface and/or atmospheric momentum, thermodynamic, and turbulence equations to directly account for urban effects

Allows prediction within UCL

Based on vegetation canopy model of Yamada (1982)

Vegetation parameters replaced with urban terms: Brown and Williams ; Masson; Martilli; Sievers ; Dupont; LLNL

From Masson (2000)

From Masson (2000)

Rough, warm urban simulationRough, warm urban simulation

USES OF MESOMODELS IN USES OF MESOMODELS IN NYC/DHS/UDSNYC/DHS/UDS

DESIGN OF MESONET: SFC AND PBLDESIGN OF TRACER STUDIESFORECASTS FOR TRACER STUDIESPARAMETERIZATIONS FOR MASS

CONSISTENT MESOMODELSUPPER BC FOR

– CFD MODELS– CANYON WIND MODELS