UNIVERSITY OF ALASKA FAIRBANKS 1 WRF/CHEM – Model Performance/Control Measure Benefits Nicole Mölders, Huy N.Q. Tran, Ketsiri Leelalakulum, Trang T. Tran Acknowledgements Heather Angelhoff, Jim Conner, Deanna Huff, Ron Lowell, Jim McCormick, Nicole Svengaard, and Todd Thompson, WRCC for observational data Catherine F. Cahill, Tom Carlson, Bob Dulla, Rob Ellemann, Javier Fochesatto, Gerhard Kramm, and Jim Conner for fruitful discussion

UNIVERSITY OF ALASKA FAIRBANKS 2 Modeling, input data, analysis Used Alaska-adapted WRF/Chem (Mölders et al. 2010) AK background concentrations cold region dry deposition modified for “winter” season modified land-use data for Fairbanks, towns/villages “to exist” Alaska Emission allocation Model (AkEM, Mölders 2009, 2010) Performed simulations with NEI2005 for November 2005 to February 2006 NEI2008 for October 2008 to March 2009 Performed evaluation by means of Surface meteorological and aerosol measurements at various sites Speciation data Mobile aerosol and temperature measurements

UNIVERSITY OF ALASKA FAIRBANKS 3 Land-use data Fairbanks is main emission source for precursors Red aerosol sites for 2005/06 evaluation Blue SODAR site for 2005/06 evaluation Crosses radiosonde sites Black met stations Street network

UNIVERSITY OF ALASKA FAIRBANKS 4 PM 2.5 concentrations at breathing level vary in time and space, response to transport and transformations

UNIVERSITY OF ALASKA FAIRBANKS 5 Performance evaluation Few evaluations exist for high latitudes due to sparse data availability Mölders et al. (2010) assessed WRF/Chem for May to August 2006 based on 2 aerosol sites Tran et al. (2011) assessed WRF/Chem for three weeks in January 2000 based on 3 aerosol sites Mölders et al. (2011) assessed WRF/Chem for November 2005 to February 2006 based on 4 aerosol sites Winter 2008/09 huge measurement campaign => unique evaluation opportunity

UNIVERSITY OF ALASKA FAIRBANKS 6 Evaluation 2005/06 shows better skill of WRF/Chem in upper than lower troposphere WRF/Chem on average captures multiple inversion structure Underestimates strength of inversion Positive wind speed bias in lower ABL Negative wind speed bias other wise WRF/Chem too dry radiosonde mean WRF/Chem mean bias RMSE correlation From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 7 On average over all sites in the study domain WRF/Chem acceptably simulates the meteorological conditions of winter 2008/09 From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 8 (Dew-point) temperature performance strongly differs among months Radiation performance decreases as irradiance increases Taylor diagrams quantify the similarity between the simulation and observations in terms of their correlation, centered RMS difference and the amplitude of their variations From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 9 WRF/Chem simulations are within the good range at the majority of sites, forecast episodes Simulations with >30% of simulated values in agreement with observations within a factor of 2 are good (Chang and Hanna 2002) Data for all hours and 24h-averages for winter 2008/09 1:1 Factor 2 Factor 3 From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 10 Winter 2008/09 FRM and BAM-measured 24h- average PM 2.5 -concentrations agree well, within a factor of two for values greater than 15µg/m 3 From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 11 WRF/Chem and mobile measurements of PM 2.5, temperatures agree acceptably in December 2008 PM 2.5 -underestimation may be partly due fact that measurements were made along line source mean bias 2.4K mean error 4.1K mean bias-6.3  g/m 3 mean error 18.8  g/m 3 FB12.3FE91.4 NMB-26% NME78% fac234% Results shown in this slide are funded by AUTC From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 12 PM goals vs. criteria Performance goals: Level of accuracy that is considered to be close to the best a model can be expected to achieve (Boylan 2004) Performance criteria: Level of accuracy that is considered to be acceptable for regulatory applications (Boylan 2004) EPA considers performance goals and criteria as a function of concentration

UNIVERSITY OF ALASKA FAIRBANKS 13 EPA-proposed performance goals Based on Fractional Mean Error (NME) and Fractional Mean Bias (NMB) performance goals should vary as a function of species concentrations (Boylan 2002) More abundant species should have a NME  +50% and NMB  ±30% Less abundant species should have less stringent performance goals Goals should be continuous functions with the features of Asymptotically approaching +50% NME and ±30% NMB for concentrations (mean of the observed and modeled concentrations) > 2.5  g/m 3 Approaching +200% NME and ±200% NMB for extremely small concentrations (mean of the observed and modeled concentrations)

UNIVERSITY OF ALASKA FAIRBANKS 14 WRF/Chem performs excellent for low concentrations, tends to overestimate at moderate, underestimate at rel. higher concentrations NME decreases with increasing concentration NAAQS From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 15 Difficulty for unusually cold October 2008, FNSB BAM in October, February, March, Q4 downtown sites From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 16 WRF/Chem underestimates the # of cases with PM 2.5 <15  g/m 3 in winter 2008/09, fails to capture the really high extremes, acceptable around NAAQS and design value NAAQS From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 17 WRF/Chem overestimates [PM 2.5 ] in October, probably due to too high emissions, acceptably captures the temporal evolution of PM 2.5 From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 18 Over entire winter 2008/09 NH 4 is underestimated by a factor of 9 probably due to too low NH 3 emissions NO 3 is about 4.6 times < observed Aerosol chemistry NH 3 -poor Literature review says that pets (cats and dogs) may emit huge amounts of NH 3 Dog kennels, caribou herds, livestock on Chena Hot Springs Rd may be non-accounted sources From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 19 WRF/Chem performance varies among sites From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 20 Difficulties with NH4 except for North Pole From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 21 Control measure benefits Simulations with all point-source emissions switched off for winter 2005/06 (NPE) Simulations with  Various “woodstove replacement” programs (WSR, WSS1, WSS2)  Introduction of low sulfur fuel for domestic heating fuel and oil burning facilities (LSF) Calculation of relative response factors and new design values

UNIVERSITY OF ALASKA FAIRBANKS 22 The relative response to “switching off” point- sources is most beneficial for the outdoors especially where isolated point sources exit Hashed: significant differences at 95% confidence From: Mölders et al Valid for November 1, 2005 to February 28, 2006

UNIVERSITY OF ALASKA FAIRBANKS 23 For a “weak” woodstove replacement program as assumed in this study the relative response is low Sensitivity studies with more replacement indicate much stronger responses Hashed: significant differences at 95% confidence From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 24 A rigors woodstove replacement program yields strong response in the nonattainment area Hashed: significant differences at 95% confidence Valid for October 1-15, 2008 From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 25 The relative response to introduction of low sulfur fuel is most beneficial in the eastern part of the nonattainment area sources exit Hashed: significant differences at 95% confidence From: Mölders et al. 2011

UNIVERSITY OF ALASKA FAIRBANKS 26 Preliminary findings, conclusions and recommendations WRF/Chem simulations are within the good range at the majority of sites, forecast episodes Quality of performance varies among episodes, sites Speciation data suggests underestimation of NH 3 emissions In the simulations, the situation was NH 4, VOC-limited Speciation data suggest underestimation of NH 3 emissions RRF best for very strong woodstove replacement program RRF for introduction of low sulfur fuel, “switching off” point- sources most beneficial outside the nonattainment area The benefit of introduction of gas in the center of Fairbanks and North Pole should be examined A comparison WRF/Chem and CMAQ should be done