=========================== INTRODUCTION ===================================

This document serves to discuss the Humboldt Bay Harbor Entrance 
wave forecast results (available at http://www.wrh.noaa.gov/eka/swan).  
This document discusses how to interpret the model output, what models 
were used to produce the output, and how to obtain additional information.

==================  INTERPRETING MODEL RESULTS =============================

Three results are presented in the model output.  These results include 
the significant wave height (Hs), peak wave direction, and areas 
experiencing increased chance for hazardous waves. Model results are 
reported in Pacific Standard Time (PST).

The significant wave height is defined as the average wave height of the 
highest third of observed waves.  The web output displays significant wave
height in feet. The significant wave height is interpretted from the 
colormap presented in the image.  A colorbar is located at the top of the
image to give scale to the colormap.  In general cooler colors (blues, 
greens, etc) represent lesser wave height and warmer colors (orange, reds,
etc) represent greater wave height.

The peak wave direction is the direction of the most energetic wave 
component.  The peak wave direction is denoted with an arrow pointing in 
the direction of wave propagation.

The areas experiencing increased wave breaking probability or greater wave
steepness is delineated by black lines.  These regions are identified by 
using two criteria.  The first criteria applied is an experimental 
wave energy dissipation equation (Smith et al. 1998).  This equation is used
to approximate the rate of wave energy dissipation from wave breaking.  The
second criteria used is a wave steepness criteria defined as the 
significant wave height normalized by the average wave length.  Thresholds
are being calibrated to reliably identify hazardous wave conditions.

Please note that these results are highly experimental and feedback would
be appreciated regarding the performance of these results to actual 
observations.  Refer to the contacts listed below to find out how you can 
help.

================================ MODELS =====================================

SWAN - Simulating WAves Nearshore
SWAN is a physics based wave model for computing spectral wave energy within 
the nearshore environment.  SWAN was developed by the department of 
environmental fluid mechanics at Delft University in the Netherlands.  The 
SWAN model is being implemented at the Weather Forecasting Office (WFO) in 
Eureka, California.  This SWAN implementation uses NOAA's WaveWatch III (WW3) 
global, deepwater wave model and wind grids locally forecasted at the Eureka 
WFO to drive the SWAN model. The model routes the spectral wave energy from 
WW3 through a low resolution (3.5 km) outer grid to a high resolution (50 m) 
inner grid based around the Humboldt Bay harbor entrance.  The SWAN model 
routes the spectral energy while accounting for energy sinks and sources such
as bottom friction and wind.  The highest resolution grid also uses tidal 
current data produced from a hydrodynamic circulation model (ADCIRC see below) 
to produce a first order approximation of wave-current interaction at the 
harbor entrance.  For more information regarding the SWAN model, please visit 
the SWAN homepage (http://fluidmechanics.tudelft.nl/swan/).

ADCIRC - ADvanced CIRCulation
ADCIRC is an advanced circulation model for oceanic, coastal, and estuarine 
waters.  ADCIRC solves the equations of motion for a moving fluid on a 
rotating earth.  This model was developed through the efforts of the 
Institute of Marine Sciences at the University of North Carolina at Chapel 
Hill and the Department of Civil Engineering and Geological Sciences at the 
University of Notre Dame.  ADCIRC has been applied to the Humboldt Bay 
region.  ADCIRC is used to resolve tidally induced currents in and around 
Humboldt Bay for one way coupling with the SWAN model's highest resolution 
grid. For more information regarding the ADCIRC model, please visit the ADCIRC 
homepage (http://www.marine.unc.edu/C_CATS/adcirc/adcirc.htm).

=========================== PROJECT HISTORY ==================================
Section to be added.

========================== CONTACT INFORMATION ===============================

TROY NICOLINI
Warning Coordination Meteorologist
National Oceanographic and Atmospheric Administration (NOAA)
National Weather Service (NWS)
Eureka Weather Forecasting Office (WFO)
300 Startare Drive
Eureka, CA 95501-6000
Telephone: (707) 443-6484 ext.223
Fax: (707) 443-6195
E-Mail: troy.nicolini@noaa.gov

GREG CRAWFORD, PHD
Professor and Chair
Department of Oceanography
Humboldt State University
1 Harpst Street
Arcata, CA 95521-8299
Telephone: (707) 826-3466
Fax: (707) 826-4145
E-Mail: greg.crawford@humboldt.edu

============================== REFERENCES =====================================

Wave breaking on a current at an idealized inlet : Coastal Inlets Research Program, inlet
laboratory investigations / by Jane M. Smith ... [et al.] ; prepared for U.S. Army Corps
of Engineers. 57 p.: ill.; 28 cm.
Accessed Online 26 May 2005
http://cirp.wes.army.mil/cirp/pubs/pdf/TR-CHL-98-31.pdf