NOUS41 KWBC DDHHMM
PNSWSHTechnical Implementation Notice XX-XX
NOAA’s National Ocean Service Headquarters Washington DC
Related by National Weather Service Washington DCxxxx xM EST xxx xxx xx 2011To:

Subscribers:-Family of Services-NOAA Weather Wire Service-Emergency Managers Weather Information Network-NOAAPORTOther NWS and NOS partners and NWS and NOS employees

From:Peter Stone
Chief, Oceanographic DivisionNOS Center for Operational Oceanographic Products andServices (CO-OPS)

Subject:
Implementation of National Ocean Service’s new
Oceanographic Forecast Modeling System for Chesapeake Bay,
Effective March 29, 2011
Effective March 29, 2011 beginning at 1500 Coordinated Universal
Time (UTC) (10AM EST), the NOAA/National Ocean ServiceChesapeake Bay Operational Forecast System (CBOFS) will beimplemented on NOAA’s Central Computer System (CCS) operated by
NCEP Central Operations (NCO).
The new implemented CBOFS
will be replacement of the NOS’ two-dimensional version of CBOFS
run on NOS’ computer system. The new version of CBOFS uses athree-dimensional, numerical ocean circulation model and theforecast horizon is extended from 30 to 48 hours.
The newversion of CBOFS will now provides users with nowcasts(predictions for near present) and forecast guidance of thethree-dimensional physical condition of the Chesapeake Bay,
including 3-D water currents, water temperature, and salinity as
well as surface water levels.

The three-dimensional ocean model used by the new version ofCBOFS is the Rutgers University’s Regional Ocean Modeling
System, a community-based, free-surface, hydrostatic, primitiveequation ocean model which uses stretched, terrain-following
sigma coordinates in the vertical and curvilinear coordinates in
the horizontal. The CBOFS grid has 332 x 291 points in thehorizontal. The finest grid resolutions in the x- and ydirections are 34m (111 feet) and 29m (95 feet), respectively,
and the coarsest resolutions are 4895m (3 miles) and 3380m (2.1miles), respectively. The vertical grid follows the terrain andconsists of 20 model levels. The CBOFS domain was designed toinclude the whole of the Chesapeake Bay and a piece of the shelf
to allow a realistic interaction between the shelf and theentrance to the Bay.
CBOFS has four daily nowcast and forecast cycles at 0, 6, 12,
and 18 UTC and operates within NOS Coastal Ocean Modeling
Framework (COMF). The meteorological forcing for CBOFS nowcast
cycles is provided by hourly surface wind analyses from NCEP’s
Real-Time Mesoscale Analysis (RTMA) and surface heat flux fromNCEP North American Mesoscale (NAM) weather prediction model.
River discharge is estimated using near-real-time observations
from U.S. Geological Survey river gauges. Oceanographic
conditions on CBOFS’ lateral boundary on the shelf are estimatedbased on subtidal water level forecast guidance from NWS ExtraTropical Storm Surge (ETSS) Model and adjusted by observed
subtidal water level s at NOS water level gauges,tides fromAdvanced CIRCulation Model (ADCIRC ) ec2001 tide database, andU.S. Navy Coastal Ocean Model (NCOM) temperature and salinity
nowcasts.
The CBOFS forecast cycles rely on meteorological forcing isprovided by NAM model forecast guidance and river discharge isestimated by persisting the most recent observations for theentire forecast period.
On the lateral boundary, future waterlevels are estimated based on subtidal water level forecast
guidance from the NWS Extra-Tropical Storm Surge Model and tides
from the Advanced CIRCulation Model (ADCIRC) while watertemperature and salinity conditions are based on NCOM forecastguidance.

The output delivery timing of the CBOFS on CO-OPS servers or web
page will not be impacted by this implementation. However, anincrease in the data volumes is expected due to the extension
out to 48 hours.
Gridded and point forecast guidance from CBOFS will be available
in netCDF files on the NCEP server at NOAA’s Web Operations
Centers (WOC) (ftpprd.ncep.noaa.gov) in the directory/pub/data/nccfs/com/nos/prod/cbofs.yyyymmdd
at NOS/CO-OPS OPeNDAP server
http://opendap.co-ops.nos.noaa.gov/netcdf/and at CO-OPS THREDDS server
http://opendap.co-ops.nos.noaa.gov/thredds/catalog.html.
CBOFS output is displayed on the CO-OPS web page
http://tidesandcurrents.noaa.gov
and the NOS nowCOAST web mapping portal at
http://nowcoast.noaa.gov.
Additional information about CBOFS can be found at
http://www.tidesandcurrents.noaa.gov/models.html.
CBOFS predictions are used by commercial and recreational
mariners and fishermen, emergency managers, search and rescue
operations, and NWS marine weather forecasters.
Thedevelopment and implementation of CBOFS was a joint project ofthe NOS/ Office of Coast Survey/Coast Survey Development
Laboratory, the NOS/Center for Operational Oceanographic
Products and Services (CO-OPS), NWS/NCEP/NCO and Rutgers
University. CBOFS is monitored 24 x 7 by both NCO and CO-OPS
Continuous Real-Time Monitoring System (CORMS) personnel.
If you have any questions concering these changes, pleasecontact:
Dr. Aijun Zhang
NOS/CO-OPSSilver Spring, MD
Email: Aijun.Zhang@noaa.gov
or
Dr. Frank Aikman
Marine Modeling and Analysis Branch
Coast Survey Development Laboratory
NOAA/NOS/Office of Coast Survey
Silver Spring, MD
Email: Frank.Aikman@noaa.gov

For questions regarding the dataflow aspects with respect to theNCEP server at the WOC, please contact:
Rebecca Cosgrove
NCEP/NCO Dataflow TeamCamp Springs, MD
Email: ncep.list.pmb-dataflow@noaa.gov
For questions on how to access CBOFS digital products from COOPS servers please contact:
Rich Bourgerie
NOS/CO-OPS/Data Monitoring & Assessment Team
Silver Spring, MD
Email: tide.prediction@noaa.gov