NCEP/NOAA upgrades GFSv16 weather forecast model
vsinceac last edited by vsinceac
Starting from RUNTIME 2021-03-22 12:00 UTC, NCEP/NOAA upgraded GFSv16 weather forecast model (much more parameters/levels), see details here
Release Notes Model Global Data Assimilation System (GDAS) and Global Forecast System (GFS) Version 16.0.7 Implementation date/time March 22, 2021; 1200Z. Purpose The GDAS is the data assimilation backbone of the GFS. The GFS produces 16-day global forecasts 4 times per day. The system also includes a global ocean wave prediction model forced by the atmosphere. Changes being made for this release:
❏ Increase the number of model vertical layers from 64 to 127 and extend the model top from the upper stratosphere (~55 km height) to the mesopause (~80 km height).
❏ Employ a new scheme to parameterize both stationary and non-stationary gravity waves that are not explicitly resolved by the model.
❏ Usea new scale-aware turbulent kinetic energy based moist eddy-diffusivity mass-flux vertical turbulence mixing scheme to better represent the planetary boundary layer processes.
❏ Update the RRTMG radiation package to improve solar radiation absorption by water clouds and the cloud overlapping algorithm.
❏ Merge the operational standalone global deterministic WAVEWATCH III based wave model Multi_1 (wave_multi_1.v3.3) into the GFS system. New features include a grid redesign, wave-current interaction and improved physics optimized to more frequent atmospheric forcing
❏ Run Global Land Data Assimilation System as part of the Global Data Assimilation System.
❏ Replace the Ensemble Square Root Filter with the Local Ensemble Kalman Filter (LETKF).
❏ Implement 4-Dimensional Incremental Analysis Update (4D-IAU) technique.
❏ Turn on stochastic kinetic energy backscattering (SKEB) perturbations in ensemble forecast used in constructing background error covariances.
❏ Update variational quality control.
❏ Apply Hilbert curve to aircraft data.
❏ Use correlated observation error for Cross-track Infrared Sounder (CrIS) over sea surfaces and Infrared Atmospheric Sounding Interferometer (IASI) over sea and land.
❏ Change the format of forecast output history files from NEMSIO (binary) to compressed netCDF.
❏ Add products on seven new pressure levels (0.01, 0.02, 0.04, 0.07, 0.1, 0.2, 0.7 hPas). Made a number of other product changes.
Developed by NWS-NCEP-EMC in collaboration with NOAA-OAR and several other partners in the community. For more information on this model, please contact firstname.lastname@example.org. Runs on The National Weather Service (NWS) Weather and Climate Operational Supercomputing System (WCOSS) Community software Earth System Modeling Framework (ESMF); Cloud Radiative Transfer Model (CRTM 2.3.0); Unified Post Processing (UPP); Gridpoint Statistical Interpolation (GSI). Input GFS/GDAS uses the full set of global conventional and satellite observations. The GFS/GDAS also ingests snow coverage data and sea ice concentration data from other models in the NCEP production suite. The Wave component uses RTOFS ocean currents as forcing. Output and where to find it: https://nomads.ncep.noaa.gov, https://mag.ncep.noaa.gov, https://www.nco.ncep.noaa.gov/pmb/products/
Primary users NWS National Centers, Weather Forecast Offices, US Army, private sectors, and the global community In the future A fully coupled atmosphere-land-ocean-ice-wave system is under development. The system is scheduled to be implemented for operations in 2024 to replace the GFS.
Indeed, this is an important upgrade.
Size of the grid is well known to be important for the accuracy of the model, the smaller the better, but less known is the number of vertical layers taken into account in the calculation. One of the major improvement with this upgrade is the number of vertical layers coming from 64 to 127
vsinceac last edited by vsinceac
... and grib2 files are also much bigger now: about 550 MB by file (i.e. for each forecast), compared to 300 MB before). This is up to 0.4 TB of grib files every day (4 runtimes of 174 forecasts each)