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Application of Kolomogorov-Zurbenko Filter and the decoupled direct 3D method for the dynamic evaluation of a regional air quality model
Citation:
Kang, D., C. Hogrefe, K. Foley, S. Napelenok, R. Mathur, AND S. Rao. Application of Kolomogorov-Zurbenko Filter and the decoupled direct 3D method for the dynamic evaluation of a regional air quality model. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 80:58-69, (2013).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
Regional air quality models are being used in a policy-setting to estimate the response of air pollutant concentrations to changes in emissions and meteorology. Dynamic evaluation entails examination of a retrospective case(s) to assess whether an air quality model has properly predicted the air quality response to known changes in emissions and/or meteorology. In this study, the Kolmogorov-Zurbenko (KZ) filter has been used to spectrally decompose pollutant time series into different forcings that are controlled by different atmospheric processes affecting the predicted and observed pollutant concentrations. Through analyses of the different components influenced by different forcings in the dynamic evaluation, we can discern which of the component(s) or scale(s) of forcing are simulated well by the model and the component(s) or scale(s) of forcing needing further improvement in the model. The KZ filter has been applied to both the observed and Community Multiscale Air Quality (CMAQ) model simulated summertime ozone (O3) time series in years 2002 and 2005. The 2002-2005 time period is a good candidate for the dynamic evaluation case study because of the large NOx emission changes that occurred as a result of the U.S. Environmental Protection Agency’s (USEPA) NOX State Implementation Plan (SIP) call along with a more gradual decreasing trend in mobile emissions. Results suggest that the CMAQ model performs similarly for both years in terms of capturing the observed synoptic forcing. However, the changes in the observed ozone baseline component (i.e. longer-term variations) are not properly captured by the model at some locations. The factors contributing to the ozone baseline include emissions, boundary conditions, and other parameters that vary slowly over time. Analysis using a reduced form model developed from the sensitivity coefficients calculated from the decoupled direct method in three dimensions (DDM-3D) reveals that ground-level NOX emissions, especially those from mobile and area source sectors, may be overestimated in 2005 as there is an increase in the mean bias for the 2005 ozone simulations from its 2002 level at the majority of AQS sites located within the states affected by the NOX SIP Call.
URLs/Downloads:
KZ_DYMANICALEVALUATIONMANUSCRIPTSEP14.PDF (PDF, NA pp, 519.229 KB, about PDF)FIGURESFINAL.PDF (PDF, NA pp, 855.808 KB, about PDF)
Atmospheric Environment
