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Maynard, MA, United States

Hanna S.R.,Hanna Consultants | Reen B.,Pennsylvania State University | Hendrick E.,Epsilon Associates Inc. | Santos L.,Air Quality Associates | And 7 more authors.
Boundary-Layer Meteorology | Year: 2010

The objective of the study is to evaluate operational mesoscale meteorological model atmospheric boundary-layer (ABL) outputs for use in the Hazard Prediction Assessment Capability (HPAC)/Second-Order Closure Integrated Puff (SCIPUFF) transport and dispersion model. HPAC uses the meteorological models' routine simulations of surface buoyancy flux, winds, and mixing depth to derive the profiles of ABL turbulence. The Fifth-Generation Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) and the Weather Research and Forecast-Nonhydrostatic Mesoscale Model (WRF-NMM) ABL outputs and the HPAC ABL parameterisations are compared with observations during the International H2O Project (IHOP). The meteorological models' configurations are not specially designed research versions for this study but rather are intended to be representative of what may be used operationally and thus have relatively coarse lowest vertical layer thicknesses of 59 and 36 m, respectively. The meteorological models' simulations of mixing depth are in good agreement (±20%) with observations on most afternoons. Wind speed errors of 1 or 2 ms-1 are found, typical of those found in other studies, with larger errors occurring when the simulated centre of a low-pressure system is misplaced in time or space. The hourly variation of turbulent kinetic energy (TKE) is well-simulated during the daytime, although there is a meteorological model underprediction bias of about 20-40%. At night, WRF-NMM shows fair agreement with observations, and MM5 sometimes produces a very small default TKE value because of the stable boundary-layer parameterisation that is used. The HPAC TKE parameterisation is usually a factor of 5-10 high at night, primarily due to the fact that the meteorological model wind-speed output is at a height of 30 m for MM5 and 18 m for WRF-NMM, which is often well above the stable mixing depth. It is concluded that, before meteorological model TKE fields can be confidently used by HPAC, it would help to improve vertical resolution near the surface, say to 10 m or less, and it would be good to improve the ABL parameterisations for shallow stable conditions. © Springer Science+Business Media B.V. 2009.

Hendrick E.M.,Epsilon Associates Inc. | Tino V.R.,Epsilon Associates Inc. | Hanna S.R.,Hanna Consultants | Egan B.A.,Egan Environmental Inc.
Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA | Year: 2012

A review and an evaluation with field observations of the EPA's Plume Volume Ratio Method (PVMRM) and the Ozone Limiting Method (OLM) for use in predicting 1-hr average NO2 impacts are presented. These methods were reviewed as implemented in the ISC and AERMOD model codes. The purpose of the technical review of the OLM and PVMRM Fortran codes was to ensure that the models were coded in a manner consistent with the formulations and to assure that the model algorithms are well founded. A new data set was identified in a remote northern Alaskan village with a small power plant. Hourly pollutant data (NO, NO2, and O3) as well as meteorological parameters were measured. Power plant operating parameters and emissions were calculated based on hourly operator logs. An evaluation of the PVMRM and OLM methodologies in AERMOD with this new data set was performed. Both AERMOD/OLM and AERMOD/PVMRM overpredicted the high end NO2 concentrations by about a factor of two, but this might be caused by the fact that AERMOD overpredicts the high end NOx concentrations. This is an abstract of a paper presented at the 105th AWMA Annual Conference and Exhibition (San Antonio, TX 6/19-22/2012).

Hendrick E.M.,Epsilon Associates Inc. | Tino V.R.,Epsilon Associates Inc. | Hanna S.R.,Hanna Consultants | Egan B.A.,Egan Environmental Inc.
Journal of the Air and Waste Management Association | Year: 2013

The U.S. Environmental Protection Agency (EPA) plume volume molar ratio method (PVMRM) and the ozone limiting method (OLM) are in the AERMOD model to predict the 1-hr average NO2/NOx concentration ratio. These ratios are multiplied by the AERMOD predicted NOx concentration to predict the 1-hr average NO2 concentration. This paper first briefly reviews PVMRM and OLM and points out some scientific parameterizations that could be improved (such as specification of relative dispersion coefficients) and then discusses an evaluation of the PVMRM and OLM methods as implemented in AERMOD using a new data set. While AERMOD has undergone many model evaluation studies in its default mode, PVMRM and OLM are nondefault options, and to date only three NO2 field data sets have been used in their evaluations. Here AERMOD/PVMRM and AERMOD/OLM codes are evaluated with a new data set from a northern Alaskan village with a small power plant. Hourly pollutant concentrations (NO, NO2, ozone) as well as meteorological variables were measured at a single monitor 500 m from the plant. Power plant operating parameters and emissions were calculated based on hourly operator logs. Hourly observations covering 1 yr were considered, but the evaluations only used hours when the wind was in a 60° sector including the monitor and when concentrations were above a threshold. PVMRM is found to have little bias in predictions of the C(NO2)/C(NOx) ratio, which mostly ranged from 0.2 to 0.4 at this site. OLM overpredicted the ratio. AERMOD overpredicts the maximum NOx concentration but has an underprediction bias for lower concentrations. AERMOD/PVMRM overpredicts the maximum C(NO2) by about 50%, while AERMOD/OLM overpredicts by a factor of 2. For 381 hours evaluated, there is a relative mean bias in C(NO2) predictions of near zero for AERMOD/PVMRM, while the relative mean bias reflects a factor of 2 overprediction for AERMOD/OLM. Implications: This study was initiated because the new stringent 1-hr NO2 NAAQS has prompted modelers to more widely use the PVMRM and OLM methods for conversion of NOx to NO2 in the AERMOD regulatory model. To date these methods have been evaluated with a limited number of data sets. This study identified a new data set of ambient pollutant and meteorological monitoring near an isolated power plant in Wainwright, Alaska. To supplement the existing evaluations, this new data were used to evaluate PVMRM and OLM. This new data set has been and will be made available to other scientists for future investigations. © 2013 Copyright 2013 A&WMA.

O'Neal R.D.,Epsilon Associates Inc. | Hellweg Jr. R.D.,Epsilon Associates Inc. | Lampeter R.M.,Epsilon Associates Inc.
Noise Control Engineering Journal | Year: 2011

A common issue raised with wind energy developers and operators of utilityscale wind turbines is whether the operation of their wind turbines may create unacceptable levels of low frequency noise and infrasound. In order to answer this question, one of the major wind energy developers commissioned a scientific study of their wind turbine fleet. The study consisted of three parts: 1) a worldwide literature search to determine unbiased guidelines and standards used to evaluate low frequency sound and infrasound, 2) a field study to measure wind turbine noise outside and within nearby residences, and 3) a comparison of the field results to the guidelines and standards.Wind turbines from two different manufacturers were measured at an operating wind farm under controlled conditions with the results compared to established guidelines and standards. This paper presents the results of the low frequency noise and infrasound study. Since the purpose of this paper is to report on low frequency and infrasound emissions, potential annoyance from other aspects of wind turbine operation were not considered, and must be evaluated separately. © 2011 Institute of Noise Control Engineering.

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