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Operational Regional Hurricane Modeling at NWS/NCEP: Recent Advances and Future Plans

Vijay Tallapragada1 , Avichal Mehra1 and the EMC Hurricane Team(with ongoing collaborations with AOML, DTC, NHC, GFDL, ESRL, FIU, OU, AER

and others)

1Environmental Modeling CenterNOAA / NWS / NCEP

74th TCORF/IHC , February 26, 2020

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NWS/NCEP Operational Models

FY19 Performance

Plans for FY20

Future Plans

Outline

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Operational HWRF v12 (Hurricane Weather Research and Forecast) System

o HWRF continuously improved in the past six years through support from HFIP

o Successful community modeling approach for accelerated transition of research to operations

Three nested domains at a horizontal resolution of 13.5/4.5/1.5 kms

Formal vortex initialization and GSI-based data assimilation

Actively coupled to Ocean models in all global basins

Actively coupled to Wave model (WW3) in NHC basins

Inner-core DA including real-time data from recon missions (TDR, dropsondes, SFMR etc.)

Expanded international

partnerships & collaborations

2017 HWRF

Results from annual retrospectives

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HMON: Hurricanes in a Multi-scale Ocean coupled Non-hydrostatic model

HMON: Implements a long-term strategy at NCEP/EMC for multiple static and moving nests globally, with one- and two-way interaction and coupled to other (ocean, wave, land, surge, inundation, etc.) models using NEMS-NUOPC infrastructure. Precursor to FV3-based systems.

Operational HMON v2 at NWS/NCEP

HMON

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Operational HWRF vis-à-vis Dynamic Models: Track and Intensity Errors for 2019 till date (Late Results)

Track

Intensity

NATL

NATL

EPAC

EPAC WPAC

WPAC

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Operational HWRF vis-à-vis Dynamic Models: Track and Intensity Skill for 2019

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Operational HWRF v12 (Hurricane Weather Research and Forecast) System

2019083100Z cycle HWRF forecast for Hurricane Dorian slowing/stalling over Bahamas before turning North/North-East.

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➢ System & Resolution Enhancements▪ Framework upgrade to WRFV4.0 with bug fixes▪ T&E with 2019 FV3GFS/GDAS (v15.1) IC/BC▪ Enable using 3-hourly (instead of 6-hourly) lateral BC’s▪ High Resolution land-sea mask• Increase vertical resolution or increase domain size (d01,

d02, d03) (< 10% increase) • Test with GRIB2 inputs (vs. NEMSIO)

Scope of FY20 HWRF* Upgrades

-- Green: Included in Baseline/H220-- Orange: Tested separately as an option

➢ Physics Advancements Upgrade to the latest version of the F-A microphysics

scheme with bug fixes• Updates to the cloud overlap method in RRTMG (AER)• Test variable mixing length modification of

GFS/EDMF PBL; test other PBL schemes (MYNN; YSU)• Test latest version of SAS• Consider Thompson for microphysics• G-F cumulus scheme (ESRL)• Adjust surface flux exchange coefficients

➢ Initialization/Data Assimilation Improvements▪ Improve vortex initialization ▪ GSI code upgrades; update merging and tempdrop

processing▪ Un-flag and use a different thinning method for the

ASCAT data▪ Changes for the DA/GSI increment blending▪ Test the possibility of including the land-based radar

observations (88D Vr data) in the inner-core DA▪ Explore the new DA initialization method developed at DTC

combined with the GSI relocation method▪ Extending self-cycled system to two concurrent storms▪ Adjust satellite background covariance coefficients

➢ Other upgrades in 2020…. Switch to RTOFS data (instead of GDEM climatology) to

initialize ocean for the NATL basin (same as EPAC) Use updated coupler Adjust damping coefficients and reduce model integration

time step to avoid numerical instability Upgrade to sync with the latest EMC Post (UPP) Update to the latest version of the GFDL tracker Explore switching to HYCOM ocean coupling for all basins Test and tune three-way atmosphere-wave-ocean coupling Graphics included in operational workflow

*This is the last planned upgrade for HWRF

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Using Hurricane Irma (2017) as an example, high-resolution land-sea masks are compared for outer nest domain (D2) (top left panel) with operational HWRF (top right panel) and for inner nest domain with high-resolution mask (bottom left) with operational HWRF (bottom right).

The high-resolution mask provides a much improved representation of coastlines (and orography) for Florida, Cuba and the Bahamas.

Hurricane Irma: Comparison of coastlines for the HWRF nested domains with and without high-resolution mask

D2@4.5 KM

D3@1.5 KM

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HWRF with High-Resolution Mask: Much Improved track and Intensity skill for Hurricanes Irma and Harvey

Based on results for Hurricanes Irma and Harvey, there is good improvement in track skill (leftpanel) and intensity skill (right panel) when high-resolution mask is introduced in the HWRFconfiguration.

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Data Assimilation in HWRF2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2020+

GSI-based DAGSI hybridP3 Doppler velocityDropsondes (partial)Global Hawk dropsondesWarm-start HWRF ensembleSLP from TCVitalsSatellite radiances/winds (D03)Flight-level obs.Fully-cycled DA (EnKF/GSI)SFMRDropsondes (all with drift)G-IV Doppler velocityStochastic physics (DA)Spectral filter for incrementsDynamic obs. errors for reconWSR-88D Doppler velocityClearsky radiance data (more channels)All sky radiance data (inner core)

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HWRF observations assimilated

o Same observations used by FV3-GFS Conventional observations Clear-air radiances

o Additional observations not used by GFS Select atmospheric motion vectors All operationally transmitted

reconnaissance data (TDR, HDOB, inner core dropsondes with drift)

WSR-88D Doppler velocity (new for 2020)

RED: H220 baseline testBLUE: H220 baseline test + additional obs.

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HWRF 2020: Track and Intensity Skill for the NATL Basin (Late Results)

Improvements in skill for the NATL basin exceed 10% for both track and intensity at Day 3. Theseresults include most of system, physics, DA and coupling changes. Experiments on final tuningare ongoing.

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HWRF 2020: Track and Intensity Skill for the EPAC Basin (Late Results)

Improvements in track skill for the EPAC basin are relatively modest but still overall positive atmost lead times. Intensity skill improves at longer lead times but overall neutral. These resultsinclude most of system, physics, DA and coupling changes. Experiments on final tuning areongoing.

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System & Resolution Enhancements Upgrade/enhance dynamic core NMMB: add

capability for random perturbations in the NMMB code, improve robustness of interpolation for moving domains

Add vertical levels, revise nest domain sizes Test different advection schemes

Coupling and Post Upgrades Use the latest version of HYCOM

Product Upgrades Upgrade to sync with the latest EMC_Post (UPP)

master/develop version Update to the latest version of the GFDL tracker (from

Tim Marchok, GFDL)

Scope of FY20 HMON* Upgrades

Physics Advancements Use original IGBP (International Geosphere-Biosphere

Program) roughness length Turn on GWD over the outermost domain. Upgrade to use the latest version of the scale-aware SAS

convection scheme used in GFS Test flow-dependent horizontal mixing length to improve

the representation of horizontal diffusion.

Test WRF Single-Moment 6-Class (WSM6) microphysics scheme

Initialization Improvements Vortex initialization modifications including:o turn off smoothing in vortex relocationo turn off intensity correction if Pmin is shallower than

OBS and Vmax is stronger than OBS

-- Green: Included in M220-- Orange: Tested separately but not included*This is the last planned upgrade for HMON

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Impact of using latest HYCOM source code

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Using latest hycom improved track and intensity. Red– control; Blue– new hycomSample: 2019, 02L, 05L, 09L, 13L

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Hurricane Dorian: Increase vertical levels from 51 to 71

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Simulations of Dorain (2019-05L) using HMON suggest that increasing nz from 51 to 71 can benefit intensity forecast.

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HMON 2020: Track and Intensity Skill for the NATL Basin (Late Results)

Improvements in skill for the NATL basin exceed 10% for both track and intensity at Day 3 and 4.These results include all tested changes.

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HMON 2020: Track and Intensity Skill for the EPAC Basin (Late Results)

Improvements in skill for the EPAC basin are also significant with tracks improved by > 6% forDays 1 and 2 and intensity > 10% at Days 3 and 5. Overall positive. These results include alltested changes.

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FY2019 HWRF/HMON Configuration (maintain diversity for FY20)

HWRF HMON

Dynamic core Non-hydrostatic, NMM-E Non-hydrostatic, NMM-B

Nesting 13.5/4.5/1.5 km; 77°/18°/6°; 75 vertical levels; Full two-way moving

18/6/2 km; 75°/12°/8°; 51 vertical levels; Full two-way moving

Data Assimilation and Initialization

Vortex relocation & adjustment,Self-cycled hybrid EnKF-GSI with inner core DA (TDR)

Modified vortex relocation & adjustment, no DA

Physics Updated surface (GFDL), GFS-EDMF PBL, Updated Scale-aware SAS, NOAH LSM, Modified RRTM, Ferrier

Surface (GFDL), GFS-EDMF PBL, Scale-aware SAS, NOAH LSM, RRTM, Ferrier

Coupling MPIPOM/HYCOM, RTOFS/GDEM, WaveWatch-III HYCOM, RTOFS/NCODA, No waves

Post-processing NHC interpolation method, Updated GFDL tracker NHC interpolation method, GFDL tracker

NEMS/NUOPC No Yes with moving nests

Computation cost for forecast job

81 nodes in 98 mins 26 nodes in 95 mins

Note: Items in Red are different

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Timelines for transitioning NPS to UFS Applications (planned)

WC

OSS

Mor

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ium

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Thank You !

Questions?