The Accuracy of the Navy-Standard Surf Model-Derived Modified Surf Index and Its Sensitivity to Nearshore Bathymetric Profile Errors

Download or read book The Accuracy of the Navy-Standard Surf Model-Derived Modified Surf Index and Its Sensitivity to Nearshore Bathymetric Profile Errors written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Naval Research Laboratory's Remote Sensing Applications Branch has evaluated the sensitivity of the Navy-Standard Surf Model to nearshore bathymetric profiles, primarily focusing on the modified surf index (MSI) accuracy. The Navy-Standard Surf Model was first introduced in 1988 and is now used extensively throughout the Fleet as part of the Geophysical Fleet Meteorological Program Library and the Tactical Environmental Support System. The model is the primary software for objective forecasting of surf conditions and its accuracy is highly dependent upon the accuracy of the model inputs. The two most important inputs are the nearshore depth profile or bathymetry and the offshore wave conditions. This report describes the performance of the model relative to bathymetric profile errors. Model sensitivity to these errors is important for estimating model accuracy in denied areas where bathymetric data is less complete. The Navy-Standard Surf Model was tested against field measurement data obtained from the DELILAH experiment held at the Duck, NC, Field Research Facility in 1990. Offshore directional wave spectra, wind, longshore current, wave height, depth profile, tide, and surf zone width measurements provided a rigorous data set for evaluating model performance and sensitivity. This study focused on field measurements obtained during the week of 12 Oct 1990. Daily nearshore depth profiles were used to evaluate model accuracy relative to profile age and slope estimation error. The latter was calculated by synthetically altering the valid profiles to contain percentage slope errors. Rudimentary bottom composition-based profiles were also utilized. A total of 373 surf model runs were made using valid wind, tide, and wave inputs for the various bathymetric profiles. The statistical analysis consists of tabulations, graphical plots, and accuracy measures. The MSI.