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Grid-scale indirect radiative forcing of climate due to aerosols over the northern hemisphere simulated by the integrated WRF-CMAQ model: Preliminary results Shaocai Yu*, Kiran Alapaty, Jonathan Pleim, Rohit Mathur, David Wong, and Jia Xing Atmospheric Modeling and Analysis Division,
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Grid-scale indirect radiative forcing of climate due to aerosols over the northern hemisphere simulated by the integrated WRF-CMAQ model: Preliminary results Shaocai Yu*, Kiran Alapaty, Jonathan Pleim, Rohit Mathur, David Wong, and Jia Xing Atmospheric Modeling and Analysis Division, National Exposure Research Lab, U.S. EPA, RTP, NC 27711 *now ORAU at Atmospheric Modeling Branch, Army Research Lab, WSMR, NM 88002 Approved for Public Release; Distribution Unlimited
Largest uncertainty (IPCC, 2007): • indirect aerosol forcing
Model Description (Configuration) Calculation of indirect aerosol forcing in WRF-CMAQ (Yu et al., 2013) Aerosols: number, size, chemical composition Coupled WRF-CMAQ aerosol simulation Sulfate, BC, OC, dust CAM ice nucleation scheme (Liu et al. 2007) Aerosol activation scheme (Abdul-Razzak and Ghan, 2000, 2002) Updraft velocity, ice water content (WRF), temperature Updraft velocity, liquid water content (WRF) Cloud microphysics (Morrison): cloud vapor and water, rain, ice, snow, graupel CCN, Cloud droplet number Ice number Conc., IN Radiative transfer model: RRTMg: re(2-60) mm Cloud effective radius (re), COD Ice effective radius (rie), IOD Met fields (WRF) The 1st and 2nd IAF Glaciation IAF
Model domain 108km domain over the northern hemisphere Simulation period: August of 2006
Results (SWCF) (preliminary results) Monthly Daily August 1, 2006 CERES Obs WRF (only) with subgrid cloud-radiation effect (Alapaty et al. 2012) WRF (only) WRF-CMAQ
Results (SWCF) (preliminary results) Monthly Daily August 2, 2006 CERES Obs WRF (only) with subgrid cloud-radiation effect (Alapaty et al. 2012) WRF (only) WRF-CMAQ
Results (SWCF) (preliminary results) CERES Obs Monthly Mean for August, 2006 WRF-CMAQ significantly improves relative to WRF WRF (only) with subgrid cloud-radiation effect (Alapaty et al. 2012) WRF (only) WRF-CMAQ (Aug 1-3 mean)
Results (Shortwave cloud forcing) Comparison of Monthly means SWCF (August) over the continental U.S. (Yu et al., 2013) Land • 12-km simulations with both indirect and direct aerosol forcing (WRF-CMAQ) are the best with very good correlation coefficients • 12-km runs still underestimate SWCF over land Ocean
Results • Possible use of NH simulation results for Army Research Lab’s (ARL) globally relocatable limited-area convective-scale WRF FDDA nowcasting project • ARL is developing Weather Running Estimate-Nowcast (WRE-N) (Dumais et al., 2013) • Based on WRF-ARW model • Observation nudging-based 4-D data assimilation (FDDA) methodology • WRF-CMAQ NH simulations can provide ARL NH WRE-N nowcasting for specific locations and regions: • Initial conditions and boundary conditions • Aerosol fields
Contacts: Brian K. Eder email: eder@hpcc.epa.gov www.arl.noaa.gov/ www.epa.gov/asmdnerl
Two-way coupled WRF-CMAQ modeling System (Interaction and feedback) Meteorological Model WRF modeling System: x=12 km, 4km 34 layers Land-Surface: PX LSM PBL: ACM2 Cloud Physics: Morrison Cumulus: Kain-Fritsch, not for 4km Shortwave: RRTMg, or CAM Longwave: RRTMg, or CAM Chemical Transport Model CMAQ Modeling System: Photochemistry: CB05 59 organic and inorganic species, 156 chemical reactions Aerosol module: AE6 3 lognormal modes, organic and inorganic Emission: SMOKE In-line emission for biogenic species AQPREP Prepares virtual CMAQ compatible input met. files Coupler CMAQ-mixactivate: cloud drop, ice number conc. Direct forcing: Aerosol size, composition, conc.