NOUS41 KWBC 141450 AAC



Technical Implementation Notice 15-36, Amended

National Weather Service Headquarters Silver Spring MD

1050 AM EDT Thu Sep 14 2017


To:        Subscribers:

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network


           Other NWS Partners, Users and Employees


From:      Dave Myrick

           NWS Office of Science and Technology Integration


Subject:   Amended: Upgrade to Global-Real Time Ocean Forecast

           System (RTOFS): Effective October 17, 2017


Updated to change the implementation date from to be determined

to October 17, 2017, and include more details on the output

timing changes in the second to last paragraph before contacts.


Effective October 17, 2017, beginning with the 0000 Coordinated

Universal Time (UTC) run, NCEP will upgrade the Global-RTOFS.


The system changes include:


- An increase in the number of vertical layers from 32 to 41

hybrid layers with additional iso-level coordinate layers in the

upper ~200m.

- The coupling of the ocean component Hybrid Coordinate Ocean

Model (HYCOM) to Los Alamos National Laboratory's Community Sea

Ice (CICE) model using v4.0 of Earth System Modeling Framework


- Updated bathymetry, which improves representation of grid

points in shallow regions where minimum depth is set to 5m.

- An update of the climatology from the U.S. Navy's Generalized

Digital Environmental Model (GDEM) v3.0 to v4.2.

- An equation of state, which is updated from 9 terms to 17



Benefits of the system changes include:


- Fine vertical resolution in the oceanic mixed layer with 9

additional near surface layers.

- Anticipated improvement to air-sea boundary flux for future

coupled applications (including hurricanes).

- Improved vertical coastal ocean resolution for downstream

applications, such as the National Ocean Service Operational

Forecast System (NOS-OFS) and Eco forecasting.

- Planned addition of Sea Ice products.


Product Additions:


- The following NetCDF files will be made available on the NCEP


Sea Surface Temperature (SST) and Surface current components U,

V time series for the last day of nowcast/hindcast

SST and Surface current components U, V time series where "#"

equals day 4 or 5 of forecast      



SST and Surface current components U, V time series for days 1-3

of forecast




Where "????" is either "prog" (Prognostic) or "diag"


Where "X" is either "f" (Forecast) or "n" (Nowcast)


- The following surface files will now be available on the NCEP




Where FFF is either hourly "f00"-"f192" or "n00" or hourly "n-


- The following ice files will now be available on the NCEP




Where ??? is either "anal" or "fcst1" or "fcst2"


Details on the contents of these files are available at:


Product Changes:


- The high vertical resolution (hvr) regional NetCDF files will

be renamed on the NCEP server.  The file name changes reflect

more descriptive region names.  The file name changes are as

follows: --> --> -->


Where "HHH" is from 000-048 --> --> -->


Where "HHH" is from 001-192


- The current 3d archive files will now be available every 6

hours for both forecast and nowcast and the "a" files will

become compressed


  rtofs_glo.t00z.*.archv.a -> rtofs_glo.t00z.*archv.a.tgz


A consistent parallel feed of data will be made available on the

NCEP HTTP server once the model is running in parallel on the

NCEP Weather and Climate Operational Supercomputing System

(WCOSS) on or around September 15, 2017.  The data will be

available at the following URL:


No changes are expected to products over NOAAPORT. Users can

find the data via the NCEP ftp and HTTP servers at:


Users can find additional information about the RTOFS at the

following Environmental Modeling Center website:


The original design of the Global RTOFS was that the model would

run throughout the day with all products being available by 00

UTC the following day. With any upgrade, it is possible that

delivery times during the day may change either earlier or

later, but the final products will still always be available by

00 UTC the following day.


With this upgrade certain analysis products will be available

earlier, and certain forecast and analysis products will be

available between 20 and 90 minutes later than current

production. This change in timing will impact the NCEP Web

Services as well as NOAAPORT/SBN. NCEP is also removing the

contingency that could have caused the last 2 days of the

forecast to be canceled due to resource constraints. This means

that no part of the Global RTOFS will be pre-emptively canceled.


NCEP encourages all users to ensure their decoders are flexible

and are able to adequately handle changes in content order,

changes in the scaling factor component within the product

definition section (PDS) of the GRIB files, and also any volume

changes which may be forthcoming. These elements may change with

future NCEP model implementations. NCEP will make every attempt

to alert users to these changes prior to any implementations.


For questions regarding the changes to this model, such as

timing, please contact:

     Avichal Mehra


     College Park, Maryland

     Phone: 301-683-3746



For questions regarding the dataflow aspects of these data sets,

please contact:

     Carissa Klemmer

     NCEP/Dataflow Team Lead

     College Park, Maryland

     Phone:  301-683-0567



NWS Technical Implementation Notices are online at: