GFSv16: Further Advancements to the UFS Medium Range Weather Application in 2021
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GFSv16: Further Advancements to the UFS
Medium Range Weather Application in 2021
Fanglin Yang
NOAA/NWS/NCEP/EMC
Vijay Tallapragada, Daryl Kleist, Arun Chalwa, Jason Levit, Russ Treadon, Jeffery Whitaker, Jack Kain, Lucas Harris, Jian-Wen Bao, Jun
Wang, George Gayno, Jongil Han, Weizhong Zheng, Helin Wei, Shrinivas Moorthi, Valery Yudin, Ruiyu Sun, Linjiong Zhou, Anning Chen,
Rongqian Yang, Xingren Wu, Xiaqiong Zhou, Henrique Alves, Jessica Meixner, Ali Abdolali, Catherine Thomas, Cory Martin, Wansu Wu,
Kristen Bathmann, Phillp Peigion, Andrew Collard, Xu Li, Haixia Liu, Yanqiu Zhu, Xiujuan Su, Shelley Melchior, Wen Meng, Hui-ya Chuang,
Boi Vuong, Mallory Row, Guang-Ping Lou, Yali Ma, Jiayi Peng, Deanna Spindler, Roberto Padilla, Geoffery Manikin, Alicia Bentley, Logan
Dawson, Kate Friedman, Mark Iredell, Hang Lei, Eric Rogers, George Vandenberghe, James Abeles, Gerhard Theurich, Edward Hartnett,
Rusty Benson, Farida Adimi
UNIFIED FORECAST SYSTEM (UFS) USERS’ WORKSHOP
July 27-29, 2020.
1
GFS.v15 Implementation -- June 12, 2019
First Finite-Volume Cubed-Sphere Dynamical Core (FV3) based GFS
& GFDL Microphysics Scheme with Multiple Prognostic Cloud Hydrometers
Configuration: Outstanding Issues
● High-res: C768 (~13km) • PBL inversion
● Data Assimilation: C384 (~25km, 80 member • Cold bias in the lower troposphere in winter
ensemble)
• Surface temperature biases
● 64 layer, top at 0.2 hPa
• Biases in the upper atmosphere
● Dycore: FV3, non-hydrostatic, single precision
• Error of track forecast for strong storms (initial
● Physics: GFS Physics + GFDL Cloud
wind > 65 kts) in the Atlantic basin
Microphysics
GFS.v15 laid the foundation for further improvement of NOAA FV3-based forecast systems
2
Change History of GFS Configurations
Mon/Year Lev Truncations Z-cor/dyncore Major components upgrade
Aug 1980 12 R30 (375km) Sigma Eulerian first global spectral model, rhomboidal
Oct 1983 12 R40 (300km) Sigma Eulerian
Apr 1985 18 R40 (300km) Sigma Eulerian GFDL Physics
Aug 1987 18 T80 (150km) Sigma Eulerian First triangular truncation; diurnal cycle
Mar 1991 18 T126 (105km) Sigma Eulerian
Aug 1993 28 T126 (105km) Sigma Eulerian Arakawa-Schubert convection
Jun 1998 42 T170 (80km) Sigma Eulerian Prognostic ozone; SW from GFDL to NASA
Oct 1998 28 T170 (80km) Sigma Eulerian the restoration
Jan 2000 42 T170 (80km) Sigma Eulerian first on IBM
Oct 2002 64 T254 (55km) Sigma Eulerian RRTM LW;
May 2005 64 T382 (35km) Sigma Eulerian 2L OSU to 4L NOAH LSM; high-res to 180hr
May 2007 64 T382 (35km) Hybrid Eulerian SSI to GSI
17 years
Jul 2010 64 T574 (23km) Hybrid Eulerian RRTM SW; New shallow cnvtion; TVD tracer No change
in vertical
Jan 2015 64 T1534 (13km) Hybrid Semi-Lag SLG; Hybrid EDMF; McICA etc
resolution
May2016 64 T1534 (13km) Hybrid Semi-Lag 4-D Hybrid En-Var DA
Jun2017 64 T1534 (13km) Hybrid Semi-Lag NEMS GSM, advanced physics
Jun 2019 64 FV3 (13km) Finite-Volume NGGPS FV3 dycore, GFDL MP
GFS V16: Major Upgrades to Forecast Model
Model resolution:
Increased vertical resolution from 64 to 127 layers and raise model top from 54 km to 80 km
Physics updates
PBL/turbulence: Replaced K-EDMF with sa-TKE-EDMF
Revised background diffusivity as a stability dependent function
GWD: Added a parameterization for subgrid scale nonstationary gravity-wave drag
Radiation: Updated calculation of solar radiation absorption by water clouds; Updated cloud overlap
assumptions.
Microphysics: Updated GFDL microphysics scheme for computing ice cloud effective radius
Noah LSM: Revised ground heat flux calculation over snow covered surface; Introduced vegetation
impact on surface energy budget over urban area
Coupling to Wave
One-way coupling of atmospheric model with Global Wave Model (WaveWatch III)
Coupling to GLDAS
Spin up land states using CPC Gauge precipitation in the GDAS 00Z cycle
GFS V16: Major Upgrades to Data Assimilation • Local Ensemble Kalman Filter (LETKF) with model space localization and linearized observation operator to replace the Ensemble Square Root Filter (EnSRF) • 4-Dimensional Incremental Analysis Update (4D-IAU) • Turn on SKEB in EnKF forecasts • Update variational QC • Apply Hilbert curve to aircraft data • Correlated observation error for CrIS over sea surfaces and IASI over sea and land • Update aircraft bias correction with safeguard • Assimilate AMSU-A channel 14 and ATMS channel 15 w/o bias correction • Assimilate CSR data from ABI_G16, AHI_Himawari8, and SEVIRI_M08 • Assimilate AVHRR from NOAA-19 and Metop-B for NSST • Use CRTM v2.3.0
I/O Change and Inline Post
• The size of each forecast history file in binary (nemsio) format increased
from 17GB (64L GFS) to 34GB (127L GFS).
• A decision was made to write out history files in netCDF format with
compression. compression ratio: 5.3x (33.6 GB to 6.3 GB), with
information loss.
• The Unified Post Processor is now run inline with the model forecast to 1)
reduce I/O footprint and, 2) retain UPP data precision and accuracy because
forecast history files are now in compressed netCDF format with
information loss.
Product Changes
○ Add more pressure levels (at 0.01, 0.02, 0.04, 0.07, 0.1, 0.2, 0.7 hPas)
○ new fields : include cloud ceiling, total column and low/mid/high cloud fractions, and
radar reflectivity at 1 km/4 km and 1st/2nd model level above ground.
○ Replace filtered Shuell SLP with unfiltered SLP using same ID PRMSL
○ Replace legacy synthetic nadir GOES 12/13 with synthetic nadir ABI GOES-R products
○ Remove terrain adjustment of bufrsnd profiles
○ FSU storm genesis verification
○ See PNS for GFS V16 product removal
○ New WAVE Multi_1 computational grid grib2 files
■ Northern hemisphere 0p16 to Replace global 30 arc min and all regional grids
■ Southern Hemisphere 0p25 to Replace global 30 arcmin
■ Arctic polar-stereographic 9km to Replace Arctic 18km
■ New global extended 0p25 to Replace global extended 30 arcmin
○
7
GFS V16 Implementation and Evaluation Schedule
● Real-time parallel started: May 19, 2020
● Retrospective forecasts period: June 2019 ~ May 2020
● NCEP OD science brief: 6 Oct 2020
● EE2 Coordination meeting: 11 June 2020 ● Code Handoff to NCO: 9 Oct 2020
● PNS sent to HQ: 18 June 2020 ● SPA begins work: 12 Oct 2020
● Retrospective forecasts complete: August 31, 2020 ● NCO 30-day parallel: 21 Dec 2020
● MEG Evaluation Kickoff webinar: July 23, 2020 ● NCO OD IT brief: 27 Jan 2021
● Field Evaluation: August 3, 2020 - September 25, 2020 ● Implementation: 3 Feb 2021
● MEG Evaluation Briefing: September 24, 2020
● Field Recommendations due: September 28, 2020
8
GFS.v16 Preliminary Results
-- Success and Challenges
C768/C384 (13/25km) L127 Configuration Cycled with data assimilation
June 2019 ~ July 2020
Note: EMC Verification and Product Generation Branch Model Evaluation Team, NWS
forecast offices, OAR Labs and the user community will provide more comprehensive
evaluation of GFSv16, and provide recommendations to the NCEP Office of Director for
implementation
9
500-hPa HGT Anomaly Correlation
NH Day-5 SH Day-5
NH Die-off
SH Die-off
10
Increase is significant up to day 6Precip ETS and BIAS SCORES over the Continental US
00Z Cycle, verified against gauge data
111 hPa Temperatures : 60N-90N : Dec 2019 – Jan 2020
GFSv15 GFSv15
GFSv16-
Beta
GFSv16
GFSv16-
Beta
GFSv16
Credit: Craig12LongHurricane Track Forecast -- Still a Grand Challenge
Eastern Western
Atlantic Pacific Pacific
Dorian Humberto Gabrielle
Lorenzo
13Temperature Biases in the NH Lower Troposphere
5-Day Forecasts fit to ROBS
DJF 2019/20
June-July
2020
GFSv15
GFSv16
GFSv16
GFSv15
The large cold bias found in GFS.v15 However, New cold bias developed
in NH winter is removed in GFS.v16 in GFS.v16 in NH summer 14Climate Run: Ensemble Spread at Model Top
QBO, SAO -- w/ Unified GWD
It is still not well understood why
the spread is so large
• Operational model (GFS.v15) cannot simulate the QBO
• A QBO-like feature is captured in GFS.v16 “climate” run
with the non-stationary GWD physics (v0) included;
However, the periodicity is too short, appears to be an
downward propagating SAO.
• GWD needs further improvement. The updated
parameterization (v1) further improved the upper
Increasing damping reduced ensemble spread
atmosphere forecast (see Valery Yudin’s presentation). It in short-lead forecast but makes jet streams too
will be tested and transitioned to operation in GFS.v17/ weak in medium-range forecast
GEFSv13Gird Imprinting Issue
Spurious edge imprints Derived Aviation Product: GTG
U V
“Cubic grids based on a separate gnomonic projection for each face of the cube possess a sharp
angular discontinuity across each edge and corner. This can lead to unsightly spurious imprints in
fields derived from forecasts”
Presentation by R. James Purser, and Miodrag Rancic: Eliminating grid imprinting with a Conformal
Cubic Overset GridThank You
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