NYC METEOROLOGY: MODELS by BOB BORNSTEIN Dept of Meteorology, SJSU for DHS/UDS Meeting EML, NYC June 2004

OUTLINE URBAN MESOMODEL PROBLEM AREAS CURRENT STATUS – URBAN WEATHER/CLIMATE – MESOMODELS – MODEL URBANIZATION PROBLEM AREAS – MESOMODELS – MODELURBANIZATION OUTLOOK

SJSU STUDIES URBMET/TVM: – NYC, SFBA, PHOENIX, SAO PAULO, FOS MM5: – SFBA, ATLANTA, LA, HOUSTON WRF (PROPOSED): – HOUSTON

URBAN MESOMODEL PROBLEMS 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 MODEL BOUNDARY SURFACE? GROUND SURFACE COMBO OF GROUND, WALL, AND ROOF SURFACES ROUGHNESS HEIGHT ROUGHNESS SUBLAYER TOP

MESO-MODEL URBANIZATION SIMPLE (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 Variability A. Predominant B. Average Parameters (Kimura 1991) WATER 20%GRASS 30% CONCRETE 50%

Barrier 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 Techniques 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)

Rough, warm urban simulation

USES OF MESOMODELS IN NYC/DHS/UDS DESIGN OF MESONET: SFC AND PBL DESIGN OF TRACER STUDIES FORECASTS FOR TRACER STUDIES PARAMETERIZATIONS FOR MASS CONSISTENT MESOMODELS UPPER BC FOR – CFD MODELS – CANYON WIND MODELS