4B.1 A Mesoscale Physics Suite to Reduce PBL Errors Including Cloud-Radiation Errors from Day 1 HRRR to Week 4 Subseasonal-Global Prediction

Monday, 4 June 2018: 4:00 PM
Colorado B (Grand Hyatt Denver)
Stan Benjamin, NOAA/ESRL, Boulder, CO; and G. Grell, J. Olson, T. Smirnova, and C. Alexander

ESRL/GSD has developed a parameterization suite (turbulent mixing, deep/shallow convection, 9-layer land/snow/vegetation model) to improve PBL biases (temperature and moisture) including better representation of clouds and precipitation. This parameterization suite development has been accompanied by an effort for improved data assimilation of clouds, near-surface observations and radar for the atmosphere-land system.

Cloud-radiation representation in models for subgrid-scale clouds is a known gap from subseasonal-to-seasonal models down to storm-scale models applied for forecast duration of only a few hours. NOAA/ESRL has been applying these common physical parameterizations for scale-aware deep/shallow convection and boundary-layer mixing over this wide range of time and spatial scales with some progress to be reported in this presentation. Evaluation of components of this suite is being evaluated for cloud/radiation (using SURFRAD, CERES, METAR ceiling) and near-surface (METAR, mesonet, aircraft, rawinsonde).

The Grell-Freitas scheme (2014, Atmos. Chem. Phys.) and MYNN boundary-layer EDMF scheme (Olson / Benjamin et al. 2016 Mon. Wea. Rev.), and RUC land-surface model (Smirnova et al. 2016 Mon. Wea. Rev.) have been applied and tested extensively for the NOAA hourly updated 3-km High-Resolution Rapid Refresh (HRRR) and 13-km Rapid Refresh model/assimilation systems over the United States and North America, with targeting toward improvement to boundary-layer evolution and cloud-radiation representation in all seasons. This representation is critical for both warm-season severe convective storm forecasting, including the pre-convective environment, and for winter-storm prediction of snow and mixed precipitation.

At the same time the Grell-Freitas scheme has been applied also as an option for subseasonal forecasting toward improved US week 3-4 prediction with the FIM-HYCOM coupled model (Green et al 2017 – Mon. Wea. Rev., and Sun et al 2018 – MWR – in review).

Some progress has been made toward improved cloud-radiation with the Grell-Freitas scheme and with the updated MYNN-EDMF scheme, especially through global subseasonal forecasting tests. Use of similar evaluation for cloud and 2m temperature for 3km HRRR (and 13km RAP) forecasts at 3-6h duration and 12-60km FIM-HYCOM and FV3 global forecasts out to 3-4 weeks are being used to guide continued development.

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