Ako na forumu postoji još neko (da ne kažem "još neki ludak"
) ko koristi tj. "skida" GEFS evo informacije "iz prve ruke" u vezi promena koje će početi 23.9.2020.
Veliki fajlovi će se dodatno uvećati za oko 30%, a 00z će biti posebno "glomazan" zbog prognoze za 35 dana...
From: Brian Gross
Acting Director
National Centers for Environmental Prediction
Subject: Announcement of upgrade to the Global Ensemble
Forecast System (GEFS), coupled with the Global Wave
Ensemble System (GWES) and the NEMS GFS Aerosol
Component (NGAC), effective September 23, 2020
Effective on or about Wednesday, September 23, 2020, beginning with the
1200 Coordinated Universal Time (UTC) run, the NCEP Global Ensemble
Forecast System (GEFS) will be updated from Version 11.3 to Version 12.0.
The GEFSv12 upgrade includes implementation of Finite Volume Cubed Sphere
(FV3) dynamical core, and integration of wave (GWESv3.0.9) and aerosol
(NGACv2.5.1) components via coupling following the Unified Forecast
System (UFS) framework.
Specifics are below, and additional science and technical information can
be obtained from the Public Information Notice 20-07 released on March 4
2020:
https://www.weather.gov/media/notification/pns20-07gefs.pdfA. Specifics on Upgrade of Atmospheric Component
* Use the latest Global Forecast System (GFS) model with the FV3
dynamical core (GFSv15.1), replacing the Global Spectral Model (GSM
v12.1).
* Upgrade the physical parameterization schemes to those implemented with
GFSv15.1 including new Geophysical Fluid Dynamics Laboratory (GFDL)
microphysics.
* New perturbation techniques including 5-scale Stochastic Perturbation
of Physical Tendencies (SPPT) scheme and Stochastic Kinetic Energy
Backscatter (SKEB) scheme.
* Expand the number of ensemble members from 21 (20 perturbed and 1
unperturbed/control) to 31 (30 perturbed and 1 unperturbed/control)
members.
* Increase model horizontal resolution to 0.25 degree (~25 km) and
maintain the same resolution throughout the forecast period for the
atmosphere.
* Improved interpolation of grib2 files from the model’s native Gaussian
grid (see Note on Interpolation below).
* Removal of lower resolution output, and inclusion of new 0.25 deg
output onto NCEP web services.
* Provide the capability for weeks 3-4 forecast guidance for atmospheric
model only. Once a day at the 00Z cycle, the forecast length will extend
to 35 days with the same 31 ensemble members and uniform horizontal
resolution.
B. Specifics on Upgrade and Integration of Wave Ensemble
This upgrade includes integration of the Global Wave Ensemble System
(GWES) via one-way coupling to the atmospheric model using NEMS mediator.
The GWES becomes GEFSv12-wave with the following changes:
* Spherical spatial grid with increased resolution from 0.5 to 0.25
degree on average.
* Increase in number of members from 21 to 31.
* Extended forecast range from 10 to 16 days.
* Increased wind field intake stride from 3h to 1h due to coupling.
* Improved physics from source-term coefficients that were tuned
using an objective framework.
C. Specifics on Upgrade and Integration of Aerosol Component
This upgrade also includes integration of the NEMS GFS Aerosol Component
(NGAC) via one-way coupling to the atmospheric model using NEMS mediator.
The NGAC becomes GEFSv12-Aerosols (one additional member of GEFSv12) with
the following changes:
* Increase in horizontal resolution from 1 degree to 0.25 degree (25 km)
resolution grid.
* Update to the latest version of NASA/ESRL GOCART aerosol model.
* Implementation of the ARL Fengsha dust emissions model.
* Use of Global Biomass Burning Emissions Product extended (GBBEPx)
directly on the FV3 grid.
* Update the sulfate anthropogenic emissions to the Community Emissions
Data System (CEDS) 2014 base version.
* Increase from 2 to 4 cycles per day.
* Improved interpolation of grib2 files from the model’s native Gaussian
grid (see Note on Interpolation below).
More details on GEFSv12-Aerosol component are documented here:
https://www.nco.ncep.noaa.gov/pmb/changes/Global_Aerosols_5day_Fcsts.pdfD. Note on Interpolation of Output from Native Model Grid
For the atmospheric and aerosol components, the interpolation of grib2
files from Gaussian grid to lat-lon grids is improved in GEFS v12 by (1)
using the latest version of grib2 library, (2) employing a more advanced
utility with higher computational precision and (3) applying more
accurate interpolation schemes for special parameters such as LAND
variables, precipitation types, amount and rate.
E. Product Changes and Removals Associated with GEFSv12
The GEFSv12 is the first global-scale coupled forecast system at NCEP
following the Unified Forecast System (UFS) framework. Because of this,
there are significant changes in the data structure, resolution and
ensemble membership of products due to system unification (combining
GEFS, WAVE and NGAC), increased model horizontal resolution, and adding
an additional 10 perturbed ensemble members for atmosphere and wave.
A significant increase in the product data volume is expected due to
these changes. The GEFSv12 products disseminated via the NWS and NCEP
web servers will have some changes in the directory structures and
content as well.
