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Home > GFS Ensemble Chem Documentation

The NEMS coupled app (GFS-CHEM) includes two components: The NCEP Global Forecast System (GFS V15) and GSDCHEM. GSDCHEM is a National Unified Operational Prediction Capability (NUOPC) based chemistry component developed to replace the current NEMS GFS Aerosol Component (NGAC at 1x1°, Bhattacharjee et al., 2018; Wang, et al. 2018) GSDCHEM includes the WRF-Chem (Grell, et al. 2005) chem_driver with updates for consistency with the NASA Goddard Operational Chemistry and Aerosol Radiation and Transport (GOCART; Chin, et al., 2007) version. The chemistry and aerosol modules used for GFS-CHEM include simple sulfur chemistry, hydrophobic and hydrophilic black and organic carbon, and a 5-bin sea salt module. Additionally, included is the FENGSHA (Dong, et al. 2016) 5-bin dust module, wildfires modeling using Fire Radiative Power (FRP) and smoke emissions from the NESDIS Global Biomass Burning Emissions Product (GBBEPx; Zhang, et al., 2014; Zhang, et al., 2012). Plume rise modeling is done with a 1-d cloud model ( Freitas, 2012), and, optionally, volcanic ash emissions are also included. The global anthropogenic emission is from the Community Emissions Data System (CEDS) based on 2014 inventory. Tracers are transported by the dynamics as well as the GFS physics (GFS PBL and Simple Arakowa Shubert (SAS) deep and shallow convection parameterization). Subgrid scale wet scavenging and transport is done inside the two SAS routines. The system runs on the FV3 cube sphere C384L64 resolution (~25 km) in the NCEP Global Ensemble Forecast System (GEFS) production suite, but with GOCART simple aerosol chemistry (20 species) run to 120 forecast hours four times per day. GFS-Chem currently requires 40 nodes to run 5 days in 37 cpu minutes on the WCOSS Dell Phase III systems.

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