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Cloud-mediated radiative forcing of climate due to aerosols simulated by newly developed two-way coupled WRF-CMAQ during 2006 TexAQS/GoMACCS over the Gulf of Mexico and eastern U.S. Shaocai Yu , Rohit Mathur, Jonathan Pleim, David Wong, Steve Howard, and S.T. Rao
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Cloud-mediated radiative forcing of climate due to aerosols simulatedby newly developed two-way coupled WRF-CMAQ during 2006 TexAQS/GoMACCSover the Gulf of Mexico and eastern U.S. Shaocai Yu, Rohit Mathur, Jonathan Pleim, David Wong, Steve Howard, and S.T. Rao Atmospheric Modeling and Analysis Division, National Exposure Research Lab, U.S. EPA, RTP, NC 27711
Two-way coupled WRF-CMAQ modeling System (Interaction and feedback) Meteorological Model WRF modeling System: x=12 km, 4 km 34 layers Land-Surface: PX LSM PBL: ACM2 Cloud Physics: Lin, Morrison Cumulus: Kain-Fritsch 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 emissions for biogenic species AQPREP Prepares virtual CMAQ compatible input met. files Coupler CMAQ-mixactivate: cloud drop number conc. Direct forcing: Aerosol size, composition, conc.
Aerosols: number, size, chemical composition Coupled WRF-CMAQ aerosol simulation Sulfate, BC, dust Aerosol activation scheme (Abdul-Razzak and Ghan, 2000, 2002) Ice number Conc., IN CCN activation Cloud droplet number Updraft velocity, liquid water content (WRF) Cloud microphysics (Morrison, Lin): cloud vapor and water, rain, ice, snow, graupel Cloud microphysics (Lin, Morrison): cloud vapor and water, rain, ice, snow, graupel Cloud effective radius (re), COD Radiative transfer model: CAM: re (4-20) mm; RRTMg: re(2-60) mm Ice effective radius (rie), IOD The 1st and 2nd IAF Met fields (WRF) Glaciation IAF
Tracks of P-3 flights Tracks of ship
Model domain (12 km and 4 km), 8/1 to 8/31/2006 12 km domain • CONUS “5x” Domain • WRF-CMAQ • WRF-CMAQ-PM 4 km nested domain over Gulf of Mexico
Results (preliminary): Evaluation for PM2.5 at AIRNOW sites • Both underpredicted obs PM2.5 by -17% (Lin) and -14% (Morrison)
Results (preliminary): at IMPROVE sites • Both underpredicted obs PM2.5 by -28% (Lin) and -25% (Morrison) mainly because of underestimation of SO42- and OC
Results: (8/4/2006, 3:00 PM EST), ground-level PM2.5 and CCN1 (S=0.02%), CCN2 (S=0.05%), CCN3 (S=0.1%) • CAM-Lin: • CAM-Morrison:
Results: (8/4/2006, 12 UTC), Ground-level PM2.5, Cloud drop #, Cloud LWC, Droplet effective radius • CAM-Lin: Effective radius (mm) w4wrfout_d01_2006-08-04_00.ncf Effective radius (mm) • CAM-Morrison:
Results (Shortwave cloud forcing) Monthly means of modeled SWCF to compare with CERES obs (preliminary results) 12 km (CAM-Lin) ~250 km (2.5 degree) 12 km (CAM-Mor) • Modeled SWCF close to Obs over GA area • Model underestimated the Obs SWCF over central and NE areas (underestimated cloud)
Results (Shortwave cloud forcing) Monthly means of modeled SWCF: Interpolate to 12 km resolution for model 12 km (CAM-Lin) ~12 km (CERES) 12 km (CAM-Mor)
Results (Shortwave cloud forcing) Monthly means of modeled SWCF: Interpolate to 4 km resolution for model 4 km (CAM-Lin) 4 km (CERES) 4 km (CAM-Mor)
Results (Shortwave cloud forcing) Comparison of Monthly means SWCF: • 12-km simulations underpredicted obs SWCF by more than -23%. • 4-km simulations are better than 12-km, especially for Morrison scheme. • Mean: (watts m-2)
Results (Longwave cloud forcing) Monthly means of modeled LWCF: Interpolate to 12 km resolution for CERES 12 km (CAM-Lin) ~12 km (CERES) 12 km (CAM-Mor)
Results (Longwave cloud forcing) Monthly means of modeled LWCF: Interpolate to 4 km resolution for CERES 4 km (CAM-Lin) ~4 km (CERES) 4 km (CAM-Mor)
Results (Longwave cloud forcing) Comparison of Monthly means LWCF: • 12-km simulations underpredicted obs LWCF by more than -5.6%. • 4-km simulations are better than 12-km, especially for Lin scheme; Morrison scheme overestimated LWCF • Mean: (watts m-2) NMB (%)
Contacts: Brian K. Eder email: eder@hpcc.epa.gov www.arl.noaa.gov/ www.epa.gov/asmdnerl
Results (preliminary): Meteorology: Radiation • Mean (at Alabama-Coushatta, TX) • Models have slightly higher radiation than Obs with better results for 4 km run Missing observed cloud cover caused overestimation during the daytime Alabama-Coushatta, TX
Results (Longwave cloud forcing) Monthly means of modeled LWCF to compare with CERES obs (preliminary results) 12 km (CAM-Lin) ~250 km (2.5 degree) 12 km (CAM-Mor) • Modeled LWCF • Model underestimated the Obs LWCF over central and NE areas (underestimated cloud)