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-------- Original Message -------- 014 NOUS41 KWBC 091437 PNSWSH Technical Implementation Notice 11-10, Amended National Weather Service Headquarters Washington DC 937 AM EST Wed Nov 9 2011 To: Subscribers: -Family of Services -NOAA Weather Wire Service -Emergency Managers Weather Information Network -NOAAPORT Other NWS Partners, Users and Employees From: Timothy McClung Chief, Science Plans Branch Office of Science and Technology Subject: Amended: Change to Wave Model Products: Effective November 29, 2011. Amended to reschedule the implementation to Tuesday November 29, 2011. In addition, this change will not affect the output from the hurricane wave model as originally stated. References to the hurricane wave model and associated output files have been removed from this TIN. Effective on Tuesday, November 29, 2011, beginning with the 1200 Coordinated Universal Time (UTC) run, the National Centers for Environmental Prediction (NCEP) will modify the spectral output grid products from the Multi-grid Global Wave Model. This model is run using WAVEWATCH-III v3.14.Recent upgrades of the model to v3.14 increased the spectral resolution of the model from a 25x24 spectral domain (frequency and direction) to a 50x36 domain. For backward compatibility, however, the spectral output from the model was kept at 25x24. This upgrade will change the spectral output to match the internal model domain. The key changes are as follows: 1. The frequency spectrum will now start from 0.035 (instead of 0.0412) 2. The logarithmic increment will now be 1.07 (as opposed to 1.1). i.e., the next frequency will be 7% higher as opposed to 10% higher earlier. 3. There will be 50 frequency components as opposed to the earlier 25 frequency components (with the highest resolved frequency being 0.963 as opposed to 0.406 earlier) 4. There will be 36 directional components as opposed to the 24 directional components earlier. This means that the directional resolution will now be 10 degrees as opposed to 15 degrees earlier The spectral output files from these models are disseminated via the NCEP server at http://www.ftp.ncep.noaa.gov/data/nccf/com/wave/prod/ and ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/wave/prod/ The following files will be affected: akw.txxz.spec_tar enp.txxz.spec_tar multi_1.txxz.spec_tar wna.txxz.spec_tar where xx is the model cycle. This change will not affect the non-spectral output files from these models. The spectral products that are changing are not available on NOAAPORT or in AWIPS. Sample output files reflecting this spectral resolution change are available at: ftp://polar.ncep.noaa.gov/pub/waves/devop/ Details about the NCEP Multi-grid Wave Model are online at: http://polar.ncep.noaa.gov/waves/index2.shtml For questions regarding these model changes, please contact: Hendrik Tolman NCEP/Marine Modeling and Analysis Branch Camp Springs, Maryland 301-763-8000 ext 7253 hendrik.tolman@xxxxxxxx For questions regarding the dataflow aspects of these data sets, please contact: Rebecca Cosgrove NCEP/NCO Dataflow Team Camp Springs, Maryland 20746 301-763-8000 x 7198 ncep.list.pmb-dataflow@xxxxxxxx NWS National Technical Implementation Notices are online at: http://www.nws.noaa.gov/os/notif.htm $$
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