Effects of uncertainties in meteorological inputs on urban airshed model predictions and ozone control strategies

Abstract Although well-recognized within the photochemical modeling community, the effect of uncertainties in meteorological input on the urban airshed model (UAM) output has not been systematically evaluated. In this study, the UAM has been applied to investigate the sensitivity of ozone predictions to the choices in wind fields and mixing height profiles for the data-sparse New York metropolitan area. A set of three wind fields, in combination with spatially varying and spatially invariant mixing heights, is investigated for the July 1988 ozone episode. In general, model-predicted ozone levels were higher under the spatially varying mixing height (SVM) option than under the spatially invariant mixing height (SIM) option. SVM based UAM simulations provided better agreement between the predicted and measured ozone concentrations than SIM-based UAM simulations. However, from the regulatory standpoint, predicted ozone concentrations based on either of these mixing height options are within the range considered as acceptable. UAM simulations with emission reductions of 75% NOx and 25% VOCs (NOx-focused) reveal that the improvement in peak ozone levels under the SIM option is larger than that under the SVM option, whereas the emission reduction scenario of 25% NOx and 75% VOCs (VOC-focused) yields greater improvement in peak ozone under the SVM option than with the SIM option. Given the strong influence of mixing heights and wind fields on UAM model predictions in data-sparse areas, it is imperative that uncertainties in development of ozone abatement plans be quantified.

[1]  Roy M. Harrison.  Air pollution modeling and its applications VIII , 1993 .

[2]  J. Scire,et al.  An intercomparison of several diagnostic meteorological processors used in mesoscale air quality modeling , 1994 .

[3]  R. T. Tang,et al.  User's guide for the Urban Airshed Model. Volume 5. Description and operation of the ROM - UAM interface program system , 1990 .

[4]  R. Berkowicz,et al.  Nocturnal boundary-layer height: Observations by acoustic sounders and predictions in terms of surface-layer parameters , 1988 .

[5]  P. Thunis,et al.  Topographic Vorticity-Mode Mesoscale-β (TVM) Model. Part I: Formulation , 1996 .

[6]  D. Carson,et al.  The development of a dry inversion‐capped convectively unstable boundary layer , 1973 .

[7]  L. Schulman,et al.  Estimating Hourly Mixing Depths from Historical Meteorological Data , 1979 .

[8]  S. T. Rao,et al.  Sensitivity analysis of a nested-ozone air-quality model , 1991 .

[9]  P. Thunis,et al.  Topographic Vorticity-Mode Mesoscale-β (TVM) Model. Part II: Evaluation , 1996 .

[10]  R. C. Kessler,et al.  Analysis of Mesoscale Airflow Patterns in the South-Central Coast Air Basin during the SCCCAMP 1985 Intensive Measurement Periods , 1991 .

[11]  S. T. Rao,et al.  Sensitivity of the urban airshed model to mixing height profiles , 1994 .

[12]  Examination of the Efficacy of Voc and NOx Emissions Reductions on Ozone Improvement in the New York Metropolitan Area , 1994 .

[13]  R. Bornstein,et al.  Application of Linked Three-Dimensional PBL and Dispersion Models to New York City , 1986 .