NCEP/EMC HWRF for Global TCs







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IMPLEMENTATION INFORMATION

Highlights for HWRF's FY2017 implementation:

  1. HWRF Infrastructure Enhancements:
    The NMM core of the operational HWRF model is upgraded to latest community version referred to as V3.8.1. Increase model vertical resolution from L61 (model top 2mb) to L75 (model top 10mb) for North Atlantic (NATL), Eastern Pacific (EPAC), and Central Pacific (CPAC) basins, and from L43 (model top 50mb) to L61 (model top 10mb) for Western Pacific (WPAC) and North Indian Ocean (NIO) basins. Meanwhile, slightly reduce the sizes of the two nested domains, from 25 x 25 deg to ~24 x 24 deg for domain 2 and from 8.3 x 8.3 deg to ~7.0 x 7.0 deg for domain 3. And consider storm’s meridional movement when determining parent domain center. Besides, a new version of Geophysical Fluid Dynamics Laboratory (GFDL) vortex tracker is implemented.
  2. HWRF Physics Advancements:
    • Updated scale-aware SAS convection scheme
    • Updated Ferrier-Aligo microphysics scheme
    • Partial cloudiness modification for RRTMG radiation scheme
    • Updated air-sea momentum and enthalpy exchange coefficients
  3. HWRF Vortex Initialization and Data Assimilation Improvements:
    • Improved vortex initialization with use of a new composite storm vortex
    • Upgrades to Grid-point Statistical Interpolation (GSI) including new data sets for GSI (e.g., hourly shortwave, clear air water vapor and visible AMV’s from GOES, HDOBS flight level data)
    • Inclusion of fully cycled HWRF ensemble hybrid Data Assimilation System for Tail Doppler Radar (TDR) and priority storms
    • Increasing the blending threshold of vortex initialization (VI) and GSI analysis (from 50 to 65 kt)
  4. HWRF Air-Sea Interaction and Coupling Upgrades:
    • Reducing coupling time step from 9 min to 6 min for both ocean and wave coupling
    • Increasing vertical levels for MPIPOM-TC ocean model from 23 to 40 levels
    • Introducing Hybrid Coordinates Ocean Model (HYCOM) coupling for WPAC and NIO basins.
    • Enabling one-way coupling to wave model (Wave Watch III) for CPAC, in addition to NATL and EPAC basins.
    • Obtaining waves boundary conditions from the NCEP global wave model (Multi_1)
    • Using ROTFS data to initialize MPIPOM-TC ocean model for CPAC storms, in addition to EPAC storms
  5. HWRF Post-Processing and Product Upgrades:
    New hurricane surface wave products are included for the NATL, EPAC, and CPAC basins, which allows decommissioning of the NCEP operational Hurricane Wave model (Multi_2). Besides, maximum number of storms can be run in operational increases from 7 to 8 storms.

Highlights for HWRF's FY2016 implementation:

  1. HWRF Infrastructure/Domain Size Upgrades : The NMM core of the operational HWRF model will be upgraded to latest community version referred to as V3.7.1a. With the availability of additional computational resources on WCOSS Cray, the nested domain sizes will increase, d02 from (12°x12°) to (25°x25°), and d03 from (6.5°x7.0°) to (8.3°x8.3°). This allows the new system to provide improved storm structure forecasts and detailed smaller scale storm features. Also, HWRF will include one way coupling to wave model for AL/EP storms which would allow us to replace the Hurricane Wave model in FY17.
  2. HWRF Physics Upgrades : HWRF physics will undergo major upgrades which include a) implementation of new GFS PBL (2015 version; b) upgrade to new scale-aware SAS convection scheme for all domains; c) updated momentum and enthalpy exchange coefficients(Cd/Ch); and d) improved vertical wind profile in the surface and boundary layer. These upgraded surface and PBL schemes provide more realistic vertical wind profiles compared to the observations. These physics upgrades included in this version also help lay a solid foundation for future physics improvement of the system.
  3. HWRF Initialization Upgrades : For the first time, the system will use ROTFS data to initialize POM model for EPAC storms to have more realistic oceanic ICs and improved RI forecasts this coming season. Further, ocean coupling will be activated for all Northern Hemisphere Basins including CPAC, WPAC and NIO for enhanced forecast skill.
  4. HWRF Data Assimilation System (HDAS) Upgrades : DA changes include upgrades to GSI, assimilation of more satellite observation data in GSI (CrIS, SSMI/S, METOP-B changes) and deploying data assimilation for all storms in the East Pacific Basin along with the Atlantic Basin. These DA upgrades in the system provide for well-balanced initial conditions, eliminating initial shocks noted in previous version.
  5. HWRF Post-Processing and Product Upgrades : HWRF post processing upgrades will include changing the file naming convention in the 2015 version of HWRF to include domain and resolution information in the file name for the 2016 version. Additional simulated synthetic imagery from different satellite sensors will be included in the output files in order to provide global coverage for all oceanic basins, including:
    • GOES-13 for North Atlantic;
    • GOES-15 for East, Central Pacific;
    • SEVERI for South, East Atlantic, and Indian Ocean;
    • HIMIWARI (MTSAT-2 in 2015 version) for West, Central Pacific;
    • DMSP/F17 SSMI/S for all basins;
    • InSat-3D/Kalpana for Indian Ocean.
  6. HWRF Script Enhancements and Procedural Upgrades : For the first-time and with active help from NCO, operational HWRF in 2016 will use dev-ecflow for accelerated transition to operations. Success in this approach will provide guidelines for this to be adopted as a standard transition procedure for all future upgrades of HWRF and other operational systems.

Highlights for HWRF's FY2015 implementation:

  1. HWRF Infrastructure/Resolution Upgrades : The NMM core of the operational HWRF model will be upgraded to latest community version referred to as V3.6.1. With the availability of additional computational resources on WCOSS Phase 2, atmospheric component of the HWRF model will be upgraded from 27/9/3 km resolution to a higher resolution operating at 18/6/2 km resolution. This will allow the model to better resolve the fine scales of hurricane inner core structure and provide improved intensity, size and structure forecasts.
  2. HWRF Physics Upgrades : HWRF physics will undergo major upgrades which include RRTM-G with parameterized subgrid-scale clouds for radiation, advanced Ferrier-Aligo Microphysics, improved PBL with wind-speed dependent vertical mixing coefficient, modified GFDL surface physics with improved specification of drag coefficient for momentum, and an advanced land surface model (NOAH LSM). Radiation upgrades will improve the cloud-radiation interactions with better representation of cloud top cooling and cloud base warming. The proposed microphysics upgrades will enhance representation of the storm structure and provide more realistic distribution of hydrometeors, especially ice concentration and fall speeds. The PBL and surface physics upgrades are aimed at improved representation of hurricane surface and boundary layer structures at high wind speeds. For the first time, a 4-level NOAH land surface model will be introduced into HWRF as a replacement of the GFDL slab model. NOAH LSM upgrades will address the cold land surface temperature bias noted in the current HWRF model forecasts, and will also provide the required surface runoff and base flow variables for landfall related downstream applications of river routing model and hydrology models.
  3. HWRF Initialization Upgrades : Vortex initialization is modified with further improvements to the storm size correction and resizing the filter domain, to be consistent with the increased resolution of both HWRF model and the parent model (GFS) that provides initial and boundary conditions.
  4. HWRF Data Assimilation System (HDAS) Upgrades : Upgrade to the latest EMC GSI v5.0.0, enlarge d2 (6km) and d3 (2km) analysis domains to address discontinuity in the initial condition  between forecast domains, and for the first time, assimilate the MSLP data from tcvitals along with dropsonde data from all available aircraft recon missions including NOAA P3, GIV, AF C-130 and Global Hawkand. For non-TDR cases, use the 80-member global ensemble based one-way hybrid EnKF-3DVAR 6h forecast fields to calculate the covariance; run GSI on d2 analysis domain and add analysis increment to d3; no satellite DA on d3 analysis domain due to pronounced negative impact. And for TDR cases, run 40-member HWRF ensembles for 6h to provide more accurate, flow-dependent, vortex-dependent data assimilation covariance; run GSI on both d2 and d3 analysis domains. The GSI system will be further tuned to improve the initial analysis for all HWRF domains.
  5. HWRF Post-Processing and Product Upgrades : HWRF post processing upgrades will include additional simulated synthetic imagery from different satellite sensors.
  6. HWRF Script Enhancements and Procedural Upgrades : Operational HWRF scripts will be converted to full python based scripts, following successful implementation of hybrid ksh-Python system implemented in 2014. Operational HWRF will remain in the vertical structure and will be known as hwrf.v9.0.0 on WCOSS.
  7. Expanding HWRF Model Guidance for all Global Tropical Ocean Basins : With support from NOAA HFIP and using dedicated HFIP computational resources, starting in 2012, HWRF team at EMC has been providing JTWC with experimental real-time forecasts for the WPAC basin. By January 2014, HWRF forecasts are extended to all global tropical oceanic basins (including NIO, SIO and SP). HWRF team at EMC is responsible for determining the priority and setting up the real-time model runs based on tcvitals provided by JTWC. Although graphical HWRF products are made available to JTWC through EMC HWRF web server, there is no mechanism for disseminating forecast products to the WFOs and to the public through official NCEP channels. Following recent requests from NWS Pacific Region and JTWC to make the experimental HWRF model runs operational for WPAC, NIO, SIO and SP basins; NCEP operational HWRF will be designed to provide real-time 126-hr HWRF forecasts four times a day, for a maximum of 7 storms covering all global tropical cyclones during their entire life cycle, and will be run throughout the year. (Previous capability is limited to a maximum of 5 storms in the ALT/EPAC basins).

Highlights for HWRF's FY2014 implementation:

  1. HWRF Infrastructure/Resolution Upgrades : The NMM core of the operational HWRF model will be upgraded to latest community version ref erred to as V3.6a. Due to computational constraints, FY13 HWRF was run with a coarse vertical resolution of 42 levels with model top extending only up to 50 hPa. Proposed FY14 HWRF will have vertical resolution increased to 61 levels with model top extending up to 2 hPa. This will al low the model to have the much desired higher resolution in PBL, and resolve the upper atmosphere more accurately. Extending the model top to 2 hPa will allow the HWRF Data Assimilation System to ingest more satellite radiance data which usually peaks above 50 hPa. The nest domain si zes will be increased by 20% for the 9km domain and by 10% for the 3km domain to allow the high-resolution nests capture larger storm regions w ithin the moving domains.
  2. HWRF Physics Upgrades : HWRF physics will undergo major upgrades which include RRTM-G for radiation, modified Ferrier Microphysics w ith advection of individual hydrometeors and an advanced land surface model (NOAH LSM). Radiation upgrades will improve the cloud-radiation in teractions with better representation of cloud top cooling and cloud base warming. The proposed microphysics upgrades will enhance representati on of the storm structure and provide more realistic distribution of hydrometeors, especially ice concentration and fall speeds. For the first time, a 4-level NOAH land surface model will be introduced into HWRF as a replacement of the GFDL slab model. NOAH LSM upgrades will address the cold land surface temperature bias noted in the current HWRF model forecasts, and will also provide the required surface runoff and base fl ow variables for landfall related downstream applications of river routing model and hydrology models.
  3. HWRF Initialization Upgrades : Vortex initialization is modified with further improvements to the storm size correction and resizing the filter domain, and will better align the filtered vortex and the environment. For the first time, we will be continuously cycling the vort ex from unnamed depressions (invests) when they transition into numbered/named storms, eliminating the cold starts for tropical storms.
  4. HWRF Data Assimilation System (HDAS) Upgrades : The 80-member global ensembles based one-way hybrid EnKF-3DVAR data assimilation sys tem for HWRF will further be upgraded to include more satellite data sets and aircraft recon data sets along with the NOAA-P3 Tail Doppler Rada r data. The GSI system will be further tuned to improve the initial analysis for all HWRF domains.
  5. HWRF Ocean Upgrades : Ocean model component of HWRF will be upgraded to multi-processor MPI-POM-TC with single trans-Atlantic domain and for the first time, a 3D ocean for Eastern Pacific basin instead of the current 1-D POM. The ocean model resolution will increase from 1/ 6o to 1/12o and will have a modified feature based initialization suitable for the MPI POM-TC model.
  6. HWRF Coupler Upgrade : The single processor NCEP coupler in HWRF model will be upgraded to run on multiple processors to enable fast er communications between the atmosphere and ocean components. This is required due to increased resolution.
  7. HWRF Post-Processing and Product Upgrades : HWRF post processing upgrades will include additional simulated synthetic imagery from d ifferent satellite sensors, and will have new products requested by SPC (tornadic potential fields) and for downstream applications including H urricane Wave Model. For the first time, FY14 operational HWRF will now have complete GRIB2 support, eliminating all GRIB1 products from opera tional suite.
  8. HWRF Script Enhancements and Procedural Upgrades : Operational HWRF scripts will undergo major enhancements with better exception ha ndling features and efficiency. The new python based scripts will eliminate lot of duplication and will greatly reduce the length of HWRF scri pts in operations. They also provide for the first time the opportunity to unify various versions of the scripts used by the community and dev elopers. They also have the flexibility to add features that can be utilized for graphics and automation. Operational HWRF will remain in the v ertical structure and will be known as hwrf.v8.0.0 on WCOSS.

Highlights for HWRF's FY2013 implementation:

  1. HWRF Infrastructure/Resolution Upgrades: The NMM core of the operational HWRF model will be upgraded to latest community version currently referred to as V3.5a. Due to computational constraints, FY12 HWRF was run with a smaller domain large physics time steps (180 sec. for 3km domain). Proposed FY13 HWRF will have 20% bigger 3km domain and will include higher frequency of physics calls (every 30 sec.). In addition, nest-parent interpolations have been re-designed for improved treatment of nest boundaries and to allow advection of several microphysical variables across the domains. Another resolution related upgrade is to interpolate GDAS/GFS spectral files to 0.25 degree resolution (instead of 0.5 degree) in hwrf_prep_hybrid to get maximum benefit from global analysis and forecasts for HWRF initial and boundary conditions.
  2. HWRF New Nest Motion Algorithm: The current mass centroid based nest motion algorithm will be replaced with a new storm tracking algorithm using Tim Marchok¿s NCEP tracker functionalities. This will eliminate several problems identified with the centroid method, is more efficient in identifying and tracking the tropical systems more accurately, resulting in improved track and intensity forecasts.
  3. HWRF Physics Upgrades: HWRF physics upgrades consist of modifications to the GFS PBL based on variable Richardson number following Vickery and Mahrt (2003) for improved PBL structure in hurricanes as well as over land.
  4. HWRF Initialization Upgrades: Vortex initialization is modified with further improvements to the storm size correction and resizing the filter domain. For storms weaker than 16m/s, we eliminate the need for bogus by directly using the GFS vortex.
  5. HWRF Data Assimilation Upgrades: A major upgrade for 2013 implementation is the 80-member global ensembles based one-way hybrid EnKF-3DVAR data assimilation system for HWRF. 75% weight is given the the ensemble covariances and 25% for the static covariances. First guess fields for the analysis are taken from GDAS forecasts and all conventional datasets are assimilated, with provisions to assimilate real-time inner-core TDR/ FL/SFMR/Dropsonde recon datasets.
  6. HWRF Ocean Upgrades: Current operational procedure of 25% truncation for heat, radiation and momentum fluxes is removed in as it is found no longer needed due to improved physics in HWRF. Upgrades to multi-processor MPI-POM with single trans-Atlantic domain and 3D ocean for Eastern Pacific basin were withdrawn from 2013 implementation plans due to lack of sufficient T&E and potential increase in resources required for operational implementation on CCS. On WCOSS, this should not be a problem.
  7. HWRF Post-Processing and Product Upgrades: HWRF post processing upgrades include bug fixes for simulated synthetic imagery to reduce domain discontinuities. Apart from very high-temporal resolution track and intensity forecast data at 5-sec. interval (HTCF), ATCF style output at every 9-minute interval will be added to the suite of products.
  8. HWRF Script Enhancements and Procedural Upgrades: Operational HWRF scripts have been modified to accommodate changes due to one-way hybrid GSI, optimum utilization of CCS resources, and cross-platform compatibility required for transitioning to WCOSS in the middle of the season. Operational HWRF will remain in the vertical structure and will be known as hwrf.v7.0.0 on CCS and hwrf.v7.1.0 on WCOSS.

Highlights for HWRF's FY2012 implementation:

  1. HWRF RESOLUTION UPGRADE: For the first time in history, NCEP will be implementing a very high resolution hurricane model developed in joint collaboration with AOML/HRD. This is a resulted of a carefully drafted and executed R2O plan supported by NOAA Hurricane Forecast Improvement Project (HFIP).
  2. HWRF FRAMEWORK UPGRADES: from V3.2 to latest community version WRF NMM V3.4a: The NMM core of the operational HWRF model will be upgraded to latest community version currently referred to as V3.4a.
  3. HWRF CODE OPTIMIZATION: The HWRF team members at EMC have put substantial efforts to accomplish higher order code optimization, improved utilization of MPI functionality, design and use of I/O servers and many other code efficiency related changes in order to fit the operational HWRF run within the allocated time and resources. It is expected that the operational HWRF forecasts will be made available to the National Hurricane Center (NHC) within 80 minutes from the start of integration (about 20 minutes more than the current operational HWRF run time at 9 km resolution), with one additional compute node required per forecast (four nodes, 246 CPUs).
  4. HWRF NEW NEST MOTION ALGORITHM: The current nest motion algorithm based on dynamic pressure will be replaced with a new centroid based algorithm essential for high-resolution grids. The new algorithm is more efficient in identifying and tracking the tropical systems more accurately, resulting in improved track and intensity forecasts.
  5. HWRF PHYSICS UPGRADES: HWRF physics upgrades consist of modifications to the GFS PBL based on observational findings, improved GFDL surface physics, GFS SAS convection and Ferrier Microphysics parameterization schemes, and implementation of new GFS Shallow Convection parameterization. The cloud-permitting 3km nest is configured to explicitly resolve convection in the inner core of the hurricane. These upgrades are consistent with higher resolution grids, and have shown significant improvements in the hurricane track and intensity forecasts in our retrospective tests for two seasons (2010-2011) in both Atlantic and Eastern Pacific basins.
  6. HWRF INITIALIZATION UPGRADES: Vortex initialization is re-designed for 3 km resolution, with improved interpolation algorithms and storm size and intensity correction procedures. In addition, different composite storms are designed for application in storms designated as deep and medium respectively. Data assimilation through HWRF GSI is now included for all storms (current operational HWRF GSI is used only for deep storms). Although no inner-core observations are assimilated, HWRF uses GSI to assimilate prepbufr data in the tropical storm environment. Keeping with the upgrades of NCEP GSI, HWRF GSI will be upgraded to community version V3.5.
  7. HWRF OCEAN UPGRADES: Efforts are under way to couple the Eastern Pacific basin to 1-D POM for improved intensity forecasts in that basin.
  8. HWRF POST-PROCESSING AND PRODUCT UPGRADES: HWRF post-processor based on NCEP Unified Post Processor is upgraded to generate simulated synthetic microwave imagery from SSM/I sensors. A new very high-temporal resolution (every time step) track and intensity forecast data at 5-sec. interval will be provided at the request of NHC.
  9. HWRF Tracker Upgrades: HWRF tracker based on NCEP tracker is modified to account for tracking tropical systems at very high resolution (3 km). This will become a part of the unified NCEP tracker being considered for implementation for all NCEP models and ensembles.
  10. HWRF SCRIPTS ENHANCEMENTS AND PROCEDURAL UPGRADES: Operational HWRF scripts have been modified to accommodate triple nesting capability, higher-order optimization, configuration of I/O servers and various namelist options suitable for high resolution. These upgrades will also include changes to WPS (pre-processing), UPP (post-processing), POM upgrades and initialization upgrades. A few procedural changes will be required to run the HWRF tracker along with the post-processing to provide forecast output on time. These changes are expected to increase the efficiency and optimum utilization of CCS resources for high-resolution HWRF model runs.

Highlights for HWRF's FY2011 implementation:

  1. HWRF source code upgrade - Now based on WRF-NMM V3.2 dynamic core, with GFS deep convection scheme, and modified air-sea enthalpy exchange coefficients
  2. Coupler source upgrade - To comply with HWRF V3.2 upgrade and includes HYCOM coupling capability
  3. Replaced WRFSI with WPS - To be consistent with community WPS
  4. Initialization source code upgrade - Includes improved storm size correction and improved initial mass-wind balance
  5. Replaced NMM GSI with the community version of GSI
  6. New ocean initialization source code upgrade - includes an expanded POM East Atlantic domain
  7. New post processing source code (HWRF-UPP) - Uses a new CRTM to generate angle-corrected GOES imagery and simulated microwave imagery. There is also a separate post-processing job for simulated synthetic satellite products
  8. HWRF_PREP_HYBRID source code upgrade for V3.2
  9. HWRF scripts upgrade - Includes enhanced scripting and simplified operational procedure as well as increased system portability