RCPWAVE (Region Coastal Protection Wave)

1. RCPWAVE: Introduction

RCPWAVE is a solution of the steady-state Monochromatic Wave Mild-Slope equation for wave transformation. The NEMOS version of RCPWAVE differs in orientation and options from the original version (Ebersole, Cialone, & Prater, TR-CERC-86-4, 1986). This version has been re-oriented to be consistent with another nearshore wave model in NEMOS (STWAVE). Within NEMOS, both models have the same orientation. Also, this version of RCPWAVE handles 4 different Seaward BC schemes and also allows a variable water level specification (spatially constant). Orientation, BC specification, and conventions for this version of RCPWAVE are shown in the RCPWAVE orientation figure.

RCPWAVE orientation figure

2. RCPWAVE Quick Tips a. Performing a Simulation

Within NEMOS, all rectilinear nearshore wave models share a common GUI environment and require a similar sequence of actions to perform a simulation. It is important to note that the actual model is a separate module from data design modules, e.g., Grid Generator, WWWL, and SPECGEN. Therefore, data which appears correct in the various data design modules do not absolutely represent data in the files, until the files are re-saved within the respective data design modules. At

simulation time, the model always reads files, regardless of what is displayed in the data design modules, so when data editing activities are completed, files should be re-saved. The activities for creating an RCPWAVE simulation from scratch (i.e no previous data files) are outlined below:

1. Build or edit (and then export the spatial domain file) a uniform rectilinear computational grid oriented with the local model x-axis in a cross-shore direction. This can be accomplished using the Grid Generator.

2. Decide where model output recording stations are desired and graphically indicate their locations using the Grid Generator. Export the station file.

3. Create or edit (and save) the model seaward boundary incident wave conditions using the WWWL Editor.

4. Optionally create and save spatially-constant, event-variable water surface elevations using the WWWL Editor.

5. Start a new RCPWAVE configuration by choosing File->New->RCPWAVE Configuration or open an existing RCPWAVE configuration by choosing File->Open->RCPWAVE Configuration->File name.

6. Edit the model configuration parameters (Configuration, Solution Scheme, and Printable Output tabs).

7. Enter the required files on the Files tab.8. Save the RCPWAVE configuration file by choosing File->Save.9. Run the model by pressing the running man button on the toolbar. As the simulation

proceeds, percent completion is indicated by a slider/indicator dialog. A dialog also opens with mdessages from the model durring the simulation. You may close this window at the completion of the simulation by pressing the x button in the top right corner.

10. Analyze/visualize the simulation results using the Wave Model Visualization Code (WMV). WMV is easily invoked by depressing the eyeball button on the toolbar.

Because you have saved the RCPWAVE configuration file, you may later open this file by choosing File->Open->RCPWAVE Configuration->filename. You may then edit values and re-run the model.

b. Creating/Editing Configuration Data

c. Creating/Editing Spatial Domain Data

d. Creating/Editing Incident Wave Data

e. Creating/Editing Water Level Data

f. Establishing/Deleting Model Output Station Locations

g. Visualizing/Analyzing Results

3. RCPWAVE Files & Data Flow a. RCPWAVE Input Files b. RCPWAVE Output Files

4. NEMOS NetCDF Files

5. References

Lampiran

Grid Generator Overview

Introduction Grid Generator is the NEMOS Uniform Rectilinear Grid GUI (Grid Generator). It is the primary interface for 2-D uniform rectilinear grid models in NEMOS. This help file provides abbreviated guidance for various using Grid Generator, as well as for the various features, capabilities and conventions for Grid Generator and the underlying 2-D finite difference modeling technologies embodied within NEMOS.

Grid Generator Capabilities & Features Grid Generator provides a complete environment for preparing datasets, executing, and visualizing simulation results for a class of CHL 2-D hydrodynamic modeling technologies. Models initially supported include wave transformation models. Both RCPWAVE and STWAVE are completely supported.

Grid Generator Primary Functions Create or edit existing datasets required for model execution, which may include station placement and bathymetry definition.

Grid Generator Quick Tips o Controlling What's Displayed

The main display of Grid Generator contains spatial domain data. Surrounding a graphics area are a Display Control Bar at the top, and mouse position tracking information on the left. The basic view of spatial domain data is controlled by the various settings on the Display Control Bar:

· [Zoom Out] (full domain) · [Zoom In] (place rectangular rubber-band around sub domain [ · [Display Points] · [Display Mesh] · [Display Contours] · [Display Land] · [Display Stations]

Some features depend upon the state of the data. For example, a mesh cannot be displayed until random (x,y,z) data has been triangulated, or a uniform grid has been built. Contour data cannot be displayed until a mesh or grid has been created. Stations can only be displayed after a uniform grid has been read or created, and station data has been read or edited.

Orientation Issues Grid Generator is designed to build grids for models which may ultimately have an arbitrary local or provincial orientation. While using random data to build a grid, the orientation of the display is in the coordinate system of the imported data (Geographic, State Plane, local, etc). After a uniform grid for a model has been built (or read in), the orientation of the display is then in the local model domain; in other words, at that point, the X-axis will be along the bottom of the display. This view was translated (and possibly rotated or converted into a projection) from the original coordinate system. If the final orientation of the model has not changed from the original coordinate system, the views are the same, but with a coordinate translation. When building uniform grids, Grid Generator assigns (0,0) to the new model coordinate system origin. As the uniform model grid is originally built, the coordinates of the uniform grid in the original coordinate system can be exported into an (x,y,z) file [File->Export]. The origin (in the original coordinate system) and azimuth (actually bearing) from North of the local model X-axis is always written to the spatial domain file when initially built or edited/saved. The azimuth (bearing) of the X-axis is also displayed in the tracking area of the display.

Contouring Features Grid Generator can contour random (x,y,z) data after is has been triangulated, and uniform grid data. Contour features are set in the [View->Contours Colors] dialog.

Features which may be set include: · Color Scheme (several preset and user-defined) · No of contour intervals (30 max) · Auto-scaling or user-defined (specify min value, and ordinate + abscissa for contour

interval) {RGB spec used}

Symbol Colors

Colors may be declared for various symbols displayed in Grid Generator (RGB spec used}. Symbol colors are specified in the [View->Symbol Colors] dialog.

Symbols colors which may be set include: 1. Points/Mesh2. Land (polygons of land cells)3. Stations

Hardcopy A hardcopy of the displayed bathymetry may be obtained by choosing File|Print.

o Creating a Uniform Rectilinear Grid Grid Generator can create uniform grids at arbitrary orientations from random bathymetry/topography data. The general tasks to follow within Grid Generator in creating a uniform grid are:

1. Set desired simulation units [Edit->Units->Feet or Meters]2. Import random (x,y,z) or (x,y,d) or sequential (x,y) data from ASCII file or database [Edit-

>Import Data]3. Edit random data using various graphic and numeric editing features [Edit->Polygon]4. Triangulate (Grid Generator determines convex hull and performs Delauney Triangulation of

domain space defined by random data points) [Edit->Triangulate]5. Optionally iterate on steps(2-4) and optionally export new sets of random data points

6. Define boundaries and orientation of local model domain within triangulated domain (also specify uniform grid point spacing) [Edit->Build Uniform Grid]

7. Save new uniform grid [Edit->Export Spatial Domain File] and/or [Edit->Export Station File]

Importing Random (x,y,z) or (x,y,d) Data Random bathymetry data is imported from ASCII (x,y,z) or (x,y,d) free-format files. NEMOS models use spatial data in an (x,y,z) reference. (x,y,d) data is converted to (x,y,z) when imported. All displayed and saved data is (x,y,z). The format for importing ASCII (x,y,z) or (x,y,d) files follows:

· npts · x1 y1 z(d)1 · x2 y2 z(d)2 · ........ · xn yn z(d)npts

Data sets may be interactively added to create a composite of several sources. The combination of polygon editing features (to regionally include or exclude data) with the ability to add several data sets can provide a mechanism for compositing data in complex fashions.

Importing Random (x , y , ux , uy) Current Data

Random current data are imported from ASCII (x , y , ux , uy) free-format files. These data must be imported prior to grid construction. NEMOS models use spatial data in an (x,y,z) reference. The current data is converted as necessary when imported. All displayed and saved data are (x,y,mag,theta). The format for importing ASCII (x , y , ux , uy) files follows:

· npts · x1 y1 ux1 uy1 · x2 y2 ux2 uy2 · ........ · xn yn uxn uyn

Data may be interactively added to create a composite of several sources. The combination of polygon editing features (to regionally include or exclude data) with the ability to add several data sets can provide a mechanism for compositing data in complex fashions.

Accessing NOS Bathymetry Databases NOS databases of bathymetry data have been created in NetCDF format, and distributed with the software. The databases have been segregated into separate files on a regional spatial and vertical datum basis. For each sounding in the file, a date, lat, lon and z-value (m) is provided. Although separated regionally and by water level datum, each database file may contain literally millions of soundings. Care should be taken with the databases to sample the database to an appropriate subset which will fit in memory and be usable in a reasonable processing time. Data can be filtered in time and space using the dialogs and graphical selection tools. The database can be accessed in the following fashion:

1. Select the database file [Edit->Import Data]. The Import Data dialog is displayed. Choose Database under files of type. Navigate to the desired database file.

2. To randomly select data from the file, and draw an outline of the database geographic region, the dialog/filter may be used. When accessing the file for the first time in a session, it is suggested that the Start Date and End Date data which appear in the dialog be used (they represent the range of temporal data in the database file), but that the nth point be set to 10000. This procedure will sample every 10000th point in the file and result in a small sample in time and space of the extent of the database. It's usually adequate to obtain a graphical sampling of the geographic extent of the data. It may still take some time to complete this task.

Reselecting data from the NOS bathymetry databases1. For successive, more detailed, accesses, repeat step 1, and apply time limits and/or the

[select region] feature on the NOS Database Dialog, and then use successive [LeftMouseButton] depressions to locate the corners of a limiting polygon. Note that coordinates of the mouse location are displayed on the left of the main Grid Generator dialog. While defining the polygon, double clicking the [LeftMouseButton] closes the polygon and terminates the polygon definition mode. The polygon will be displayed during and after the definition process until deselected. Then depress [OK] on the Database

Dialog. The filter will then re-sample the entire regional database file, keeping only points within the time and geographic area indicated.

2. Data retrieved from the database will be in Geographic coordinates (deg Lat, Lon) and z (m). For use in most NEMOS technologies it should subsequently be converted to some Cartesian coordinate system (UTM or State Plane) using a projection as described below. The selected data can also be exported to an ASCII file at this point if desired.

Importing Shoreline (Sequential) (x,y) Data Shoreline data can be entered as a special case of sets of sequential data points (x,y). In this case, additional points are interpolated at a specified interval between the given points, and are assigned a specified z value. The data file consists of a number of shoreline segments sets, enabling both simple single shoreline descriptions to be specified as well as islands in the same file. Data points are interpolated within each segment at the specified interval. Segment are not connected, and data within each segment is assumed to be sequential. The format for importing ASCII shoreline files follows:

· nsegs · npts1 · x11 y11 · x12 y12 · x13 y13 · ....... · x1n y1n · npts2 · x21 y21 · x22 y22 · ....... · x2n y2n

An arbitrary number of segments and points within a segment can be specified. Interpolation intervals and z values are specified in the dialog which appears with this option.

Exporting (x,y,z) Data (x,y,z) data may exported into an ASCII file (of the above format specified by the Importing x,y,z data topic) [Edit->Export Points] at any point in the grid building process. If exported before the uniform grid is built, the file will contain all random (x,y,z) data points currently contained in memory. If exported after the local translated, rotated uniform grid is built, the grid points are exported as (x,y,z) data in the "original" (actually previous) coordinate system. It's important to note that successive translations and rotations can be performed in Grid Generator. The code only maintains knowledge about the current and immediate predecessor coordinate system. Successive coordinate transformations destroys the knowledge of the original coordinate system. Care should be taken to record sufficient data if successive transformations are performed.

Editing Random (x,y,z) Data Random (x,y,z) data may be edited with a combination of graphic and data entry features. Data may be added or deleted using individual placement methods, or within a declared polygon surrounding some sub-region of the domain. Additional editing features are available in the polygon editing feature described elsewhere. Graphical editing is often aided by zooming down to the region of interest. Some time may elapse if large data sets are present, or the data has already been triangulated (data will be re-triangulated), or contoured (data will be edited, re-triangulated and re-contoured). Display features currently selected will impact the speed at which data will be redisplayed for all editing operations.

Adding/Deleting Random (x,y,z) Data Individual (x,y,z) points may be added to the current set after random data has initially been imported. Pressing the + button on the top toolbar puts you in add mode. Once in this mode, you may click your left mouse button to add new points. You will be prompted to enter a Z value for each point. Likewise, if you press the - button on the toolbar, you are in delete mode. While in delete mode you may click on any point on the screen and that point will be deleted.

Polygon Editing (Random (x,y,z) Data More powerful editing features are available for sub-regions of the domain which are defined with a polygon. To declare a polygon, select the polygon tool from the top toolbar and then use successive [LeftMouseButton] depressions to locate the corners of the polygon. When you have completed the polygon, double click the left mouse button to close it. The polygon will be displayed during and after the definition process until deselected.

Once a polygon is selected, several editing features are available. Left click on the polygon, choose Polygon, and the following options are displayed:

· Delete points within polygon · Delete points outside of polygon · Minimum Z (enforce Z >= Zmin) of points within polygon · Maximum Z (enforce Z<= Zmax) of points within polygon · Scale Z (Z multiplied by factor) of points within polygon · Assign Z (assign a constant Z) to points within polygon · Filter Z (assign a new Z) to points within polygon which fall within a specified range of Z

values · Increment Z (Z datum shift by a constant) of points within polygon · Add points on polygon boundary (Points added at delta-r interval on boundary {using

constant Z value}) · Deselect polygon

Simple dialogs are summoned to collect the relevant editing data (constant, factor, Zmin, etc...). Closing the relevant dialog initiates the editing action. Some time may elapse if large

data sets are present, or the data has already been triangulated (data will be re-triangulated), or contoured (data will be edited, re-triangulated and re-contoured). Display features currently selected will impact the speed at which data will be redisplayed for all editing operations.

Adding (x,y,z) Points with PolyLine Points located along line segments may be added to the set using the Polyline tool .

Select the Polyline Tool from the top toolbar. Points are interpolated on the line segments at a specified interval and constant Z which are indicated on the dialog which appears when terminating the line segments. While defining the polyLine, you should click the left mouse button for each segment. To terminate drawing of the poly line, double-click the left mouse button. When the definition process is terminated, you should right-click on the poly line and choose Add Polyline Points or choose Edit->Add Polyline points. A dialog appears to collect the Z value for the points to be interpolated/added. At that point, the line marker disappears, and is replaced with the additional interpolated points. Some time may elapse if large data sets are present, or the data has already been triangulated (data will be re-triangulated), or contoured (data will be edited, re-triangulated and re-contoured). Display features currently selected will impact the speed at which data will be redisplayed for all editing operations.

Triangulating the Domain Delauney triangulation is used in Grid Generator to provide a mechanism for interpolating functions within the domain space. When selected [Edit->Triangulate], a convex hull is determined for the space surrounding all of the random (x,y,z) points, followed by triangulation of all points in the domain. The challenge of determining a "reasonable" convex hull and triangulation for an arbitrary number of points and shape is a complex algorithm. Problems for such algorithms include some of the following:

1. Many points on a straight horizontal or vertical line2. Many points very "close" together (relative to the magnitude and precision of the

coordinates)3. Floating point precision.4. Widely variable range of coordinate magnitudes and required precision in different

coordinate systems 5. Limiting Edges are not considered in the present triangulation algorithm. Shorelines are

not currently treated as edges or boundaries between land and water.

Because of the above and additional factors, robustness in convex hull and triangulation schemes is usually an issue to monitor. It is recommended that the triangulated mesh (and contours of Z) be visually checked before proceeding with uniform grid construction. Should problems result, check for (1) and (2) above and edit the random points if possible.

Specifying the Uniform Grid Parameters After triangulation of the random (x,y,z) points has completed, a uniform grid at any arbitrary orientation may be constructed within the convex hull which surrounds the random points. While it is possible to build the grid with portions outside the hull, in general, it's best to stay within it because no Z values are extrapolated outside the hull (Z=0 outside hull). If necessary, extend the hull (by adding points) to ensure adequate coverage of the area of interest. Once the domain is triangulated, a Z value for any (x,y) location within the domain can interpolated. To build the uniform grid [Edit->Build Uniform Grid] a dialog must be filled in to specify the data about the orientation, spacing, # of points in (x',y') etc. Two methods are provided:

1. Specify graphical selection of the domain space and orientation (dx',dy' or nx', ny' specified numerically)

2. Specify all data for the new grid numerically

The first method requires specification of the grid spacing, or desired number of grid points and a graphical selection of the extent and orientation of the rectangular modeling domain. Depress the Select Grid Region tool (rectangle) on the top tool bar. Move the mouse to the desired origin, and depress [LeftMouseButton] and drag the mouse in the direction and length for the desired X'-axis. Note that the azimuth(bearing)of the X'-axis is being tracked on the left side of the display. Release the LeftMouseButton and then move the mouse to the desired Y'-axis length. Remember that most models use a right-handed coordinate system. The domain indicated during these graphical selection motions will be constrained to a rectangle oriented with X' along the selected angle. Depress the [LeftMouseButton] to complete the desired rectangular modeling domain selection. If a mistake is made, you may re-select the Select Grid Region tool and repeat the above process until the selection is acceptable. After you have defined the grid region, right-click and choose Build Uniform Grid. Make sure that Manually Define Region is not checked. Press OK on the dialog. At that point, a uniform rectilinear grid will be constructed within the selected rectangular space and orientation.

The second method requires numerical specification of the spacing (or number of points), the origin (in the original coordinate system, the azimuth(bearing) of the new X'-axis, and the lengths of X'max and Y'max for the new coordinate system. To accept the selection, press OK on the dialog. At that point, a uniform rectilinear grid will be constructed within the selected rectangular space and orientation.

After applying either method of selecting the uniform grid parameters, the display will then change to the new model coordinate system (X' will be horizontal in the display). The coordinates of the uniform grid points in the previous coordinate system can be exported to an ASCII file at this point [Edit->Export Grid]. The spatial domain (ie uniform grid) file can also be saved [Edit->Export Spatial Domain File].

Editing Uniform Grid Data

Editing functions for a uniform grid are more restricted. Points may not be added or removed arbitrarily. Some editing functions relative to Z data are available using the Polygon Editing features described elsewhere. Specifically, the polygon editing features available for uniform grids are the following:

· Increment Z (Z datum shift by a constant) of points within polygon · Scale Z (Z multiplied by factor) of points within polygon · Minimum Z (enforce Z >= Zmin) of points within polygon · Maximum Z (enforce Z<= Zmax) of points within polygon · Assign Z (assign a constant Z) to points within polygon · Filter Z (assign new Z) to points within polygon which fall between Zmin and Zmax · Deselect polygon

These uniform grid features are useful for modifying exiting grids for a variety of scenarios. If grids need to be extended or truncated, the easiest procedure would be to export the existing grid to random (x,y,z) points, edit that set in a new Grid Generator session, and build the new extended or truncated grid.

o Establishing/Deleting Model Station Locations Once a uniform grid has been created (or read in), specific stations where more comprehensive data for each wave event may be specified graphically.

Select the Station tool (upside down triangle) from the top toolbar. Click at each point you wish to place a station. Once all stations have been added, you may terminate the process by reselecting the Station tool. To move or delete a group of stations, select the Selection tool (arrow). While depressing the left mouse button, drag the rubber band box around the desired stations you wish to move or delete. Release the left mouse button. At that point, all stations within that region will be visually selected. You may then place your mouse cursor over any station and move it while depressing the left mouse button. Note that all selected stations will be moved in the direction of the mouse cursor. If you wish to delete the selected stations, right-click and choose Delete. Stations are more useful for models such as STWAVE where the directional energy spectra are saved. Station data can be viewed using the Wave Model Visualization application (WMV). Stations are also used to propagate data at specific points to other models within NEMOS such as GENESIS, SBEACH and others. Station files are read into Grid Generator [Edit->Import Data->Station File] (they are also read when a configuration file is read). They are individually saved [Edit->Export Station File]. Grid Generator merely creates or edits a file with station locations identified, and passes this file to the model. Models such as RCPWAVE and STWAVE read the file, and record simulation data at the specified locations.

Model Stations as Nearshore Reference Line (and Sorting) Model stations may be used to communicate data to the GENESIS model by establishing a set of station locations which follow some criteria such as a contour seaward of breaking. In general, the stations should be established one/wave model cell, along the entire or partial reach of Y in

the wave model grid, and they must be ordered one/cell in ascending Y. If stations are intended to follow an offshore contour, it is recommended that the contour options be adjusted to clearly delineate the contour location when placing the stations. It is also recommended that the grid point locations be displayed, so that the stations may be placed as near as possible on the grid point locations. Zooming in on regions will help to delineate these locations more clearly. When all stations are placed it is highly recommended to sort the stations [Right-Click->Sort Stations] before they are saved. This feature will sort the stations in ascending values of Y, which will place them in the correct order for GENESIS. If errors are made, or other station editing (delete and/or followed by an add) is required, a resort [Right-Click->Sort Stations] should be done before saving the station locations in the file. Although station locations are communicated to the model in local model coordinates, the model indices are determined by the model, and added to the file during wave model execution. The model indices, and dy spacing are written in the station file for later reading by GENESIS or other models.

o Export Current FileAfter importing a random current file, bathymetry, and building a uniform grid, you may export a current file to be used in other modules by choosing Edit->Export Current File or selecting this option after right-clicking in the right window.

WWWL Editor OverviewIntroductionThe WWWL Editor is used for specifying and editing a variety of record-oriented data types such as waves, winds, water levels (WWWL). It is used to initially specify such data, or edit existing data sets which include large online databases. Embedded within WWWL are many sub-dialogues which are used to specify meta-data, filter data records using a variety of criteria, and perform conversions between the many conventions supported by NEMOS 2.0 products. This help file provides a brief summary of WWWL features, procedures, and conventions. It's important to note that all data being edited in WWWL is in memory only, and must be written to a file before it becomes saved, or can be used by a model or other application.

The WWWL editor contains various tabs based on the type of data you are entering. The available tabs are listed below:

Data tabThe data tab is present for all types of data being entered into the WWWL editor. The number of columns are based upon what type of data are being entered. If the Index Type (Station->Index Type) is specified as Integer, the first column contains the Index of each row of data. If the Index Type is Time, the first column is used for the date while the second column is used for the time. The remaining columns are based upon what type of data you have specified, i.e., wave data, wind data, water level data. To activate any data type, select the appropriate data type under the Station menu and select Active.Location tab

Water Levels tab

This tab allows you to enter the location parameters for your data. The parameters include mean water depth at datum, horizontal and vertical datums, and the world coordinate system.

Waves tabThis tab allows you to enter your water level attributes. Water level data have only two attributes which can be specified by the user: the system of units and the station name. This tab is only visible if water level is active in your WWWL session. To activate water level, right-click in the WWWL window, choose Water Surface Elevation, and choose active.

The only filter that can be applied to water surface elevation data is the magnitude range filter. This filter functions identically to the wave record filters.

wave record filters WWWL: Filtering Wave DataWWWL allows you to filter wave data based on several criteria such as height range, period range or transport range. The height range, period range and propagation direction range filters are identical except for the variable they are based upon. The filter can be run in two modes, inclusive or exclusive. Inclusive mode affects all records that match the filter criteria, while exclusive mode affects the records that do not match. Records that fail the filter test have the action specified by the failure mode menu applied to them. By default all records that fail are removed from the editor, however a flag value [Flag Value] can be inserted into one of the fields of the record to mark it as failing without deleting the entire record. The filter range is specified by filling in the [Minimum] and [Maximum] fields with the desired variables.

The Transport Range filter computes the longshore sediment transport by each wave and removes or flags waves that have an insignificant transport rate. This filter is useful for performing GENESIS simulations to remove waves events that will have no effect upon the result. By removing these events, the model will not waste time performing computations that are not useful.

To bring up the filter dialogs, switch to the Data tab. Right-click in the WWWL window. Select Waves, then select the corresponding range filter (Height, Period, Direction, or Transport).

This tab is only available when water level is active. To activate water levels, right-click in the WWWL window, select Water Surface Elevation, and select Active.

Wind tabThis tab allows you to enter attributes for your wind data. The attributes that are configurable for wind records are wind speed units, the direction convention, observation elevation, and duration. This tab is only visible if wind is active in your WWWL session. To activate wind, right-click in the WWWL window, choose Wind, and choose active.

The filters that can be applied to wind records are the magnitude range and direction range filters. These filters function identically to the wave record filters.

Time tabThe time reference attributes tab allows you to define the time zone that the time data occupies. Time data can be referenced to Greenwich Mean Time (GMT) or to a local standard time meridian given as degrees longitude east or west. This tab is available only if the index type is specified as "Time." To specify the index type as Time, right-click in the WWWL window, select Index Type, then select Time.

See Also:Converting Time ZonesThe time zone of the data can be changed by using the Time Zone procedure from the Conversions dialog. To bring up the Conversion dialog, select the Data tab in the WWWL editor, right-click in the window, select Convert Time Zone. Select the new time zone from the To line on the Convert between time zones dialog and enter the new meridian if converting to a local standard time meridian.

Filtering Time DataData can be filtered by time in three different ways, time period, intervals, and every nth record. The Time Period filter allows the user to choose a date and time range and either keep or remove all records which fall into the range. This is useful for reducing twenty year hindcast database data down to the years of interest for a given study.

A dialog box appears giving options to Include or Exclude data within the time range specified. Specify the Start and End dates and times for the range to consider. The "Every" entries specify "Every m days" and "Every n hours/minutes". A 1 in both fields means you want all of the records. For and entry of 2 under days, menas you want every other day, and so on. The time value is entered as hours and minutes, so that 600 is 6 hours and 0 minutes.

The Time Period Interval filter allows the user to filter a time series by some interval in time. For example, a time series with three hours between measurements could be filtered to have six hour increments by starting at the time of the second record and using a six hour interval for the filter.

The final time filter is the Every Nth Record filter. This filter thins the time series data by removing or keeping, depending on the filter sense, every record that is a multiple of the value entered into the Every field of the filter.

NEMOS Wave Propagation Angle Conventions Six Different Conventions are embedded within the various NEMOS packages. 1. Meteorologic [global orientation - magnitude & direction from North (WIS Databases use this

convention)]

2. Oceanographic [global orientation - magnitude & direction from North)3. Local Polar [local orientation - "Math" sense" - most local 2-D models use this convention]4. Shore_Ref 1 [local shore-referenced - GENESIS uses this]5. Shore_Ref 2 [local shore-referenced - not used currently]6. Shore_Ref 3 [local shore-referenced - WIS Phase III transformation convention]

Note that all local conventions require some azimuth (of x-axis or "local zero") for conversion purposes. The conventions are illustrated below:

NEMOS Wind Propagation Angle Conventions Seven Different Conventions are embedded within the various NEMOS packages: 1. Meteorologic [global orientation - magnitude & direction from North (WIS Databases use this

convention)] 2. Oceanographic [global orientation - magnitude & direction from North) 3. East-North [global orientation - East & North Components] 4. Local Polar [local orientation - "Math" sense" - most local 2-D models use this convention] 5. Local Cartesian [local orientation - Math x-y components] 6. Shore_Ref 1 [local shore-referenced] 7. Shore_Ref 2 [local shore-referenced - not used currently]

Note that all local conventions require some azimuth (of x-axis or "local zero") for conversion purposes. The conventions are illustrated below:

Getting Data into WWWL WWWL is a tabular editor for wind, wave and water level data. Common data sources include databases, analyzed gage data, statistically-derived datasets, theoretical cases, and data derived from other model simulations. Four methods are available to initially get data into WWWL:

Typing/Editing Data Records WWWL is a tabular editor. Data may be typed directly into the fields. To make the appropriate fields available, toggle or select the appropriate widgets for [Index Type] (Time, Integer Index, or None) and the appropriate data type(s) (Water Surface Elev, Waves, Winds). After ensuring that the fields are enabled, place the cursor in the desired field, and type in the numeric value. Pressing [Enter] after each entry moves the cursor to the next field or record. Data may be edited using conventional text operations (cut, paste, delete, insert, etc) available in X window text fields. Once data is entered for several records, additional records may later be inserted before a selected record [Cntrl+I], appended after a selected record [Cntrl+A], or deleted [Cntrl+D].

Attributes about the data must be entered in sub-dialogs for the various data types. For example, water level units are set by summoning the Water Surface Elevations sub-dialog [Water Surface Elev] and then selecting [ft or m]. Wind and wave attributes (units and convention) are established in similar fashion.

Importing ASCII Files

Data files for winds, waves, and water levels used within NEMOS 2.0 are written as NetCDF binary files. ASCII files of this type of data may be imported directly into WWWL [Import]. The ASCII file is free format, and should contain data in the following general form:

nrecords itagtype iwl iwav iwind

taga1 tagb1 Eta1 H1 T1 theta1 Ua1 Ub1

taga2 tagb2 Eta2 H2 T2 theta2 Ua2 Ub2

...

taganrecords tagbnrecords Etanrecords Hnrecords Tnrecords thetanrecords Uanrecords Ubnrecords

Most of the data following the first record is optional and the contents depend upon the value of the flags on the first record as described here:

nrecordsNumber of records to follow

itagtyprecord tag type (0=none, 1=integer index, 2=time)

iwlwater level data included (0=no, 1=yes)

iwavwave (H,T,theta) data included (0=no, 1=yes)

iwindwind data (Ua,Ub) included (0=no, 1=yes)

Data on following records is as follows: taga

a record tag which may be an integer index code (if itagtyp = 1), or the day of year (if itagtyp = 2) as: yyyymmdd

tagb(used only if itagtyp=2) time of day as: HHMM

Etawater level deviation from still water level (used only if iwl = 1)

HWave height (used only if iwav = 1)

TWave period (used only if iwav = 1)

thetaWave propagation direction (used only if iwav = 1)

Uawind magnitude or 1st component (used only if iwind = 1)

Ubwind direction or 2nd component (used only if iwind = 1)

Note: at least one value of iwl, iwav, or iwind must be =1. Units and conventions for the various data must then be set using the various dialogs within WWWL (described elsewhere in this document).

Reading Databases or NEMOS Station Files NEMOS uses standardized files for station data in most of its applications. These data files are written in NetCDF format, and are shared or written by many applications. Station files may contain data at many stations, as well as many wave component descriptions, and data at one station and one component may be read into WWWL for editing or analysis. Some applications use 2 components of wave data and in these circumstances, two sessions of WWWL are invoked; one for each component.

WIS databases

Prior to 2004, WIS databases were written in this format (see WIS Data and Format - pre-2004), and are provided on a regional basis. Station files are read into the application using WWWL using the [File->Open->WWWL Files->Filename] menu option. A station (and possibly a wave component) must be selected at that time. Data may be edited within WWWL. The wizard for importing pre-2004 WIS data is:

Note: If the spectral-based significant wave height, peak period, and peak direction are to be imported, the user must check the "As specified below" button and check / fill in the appropriate boxes.

Since the beginning of 2004, WIS data are no longer analyzed for its primary and secondary components. That operation is left to the user. Instead only the spectral-based significant wave height, peak period (two methods of analysis) or mean period, and peak direction (two methods of analysis) are provided (see WIS Data and Format - Current). The wizard for importing currently-provided WIS data is:

Here the user specifies exactly what data they want to import and use. Data may be edited within WWWL.

Wave Attributes and Procedures This tab allows you to specify information such as the direction convention and units for wave records. This tab is only visible if waves are active in your WWWL session. To activate waves, right-click in the WWWL window, choose Waves, and choose active. The wave component name field is the name of the NetCDF variable which will contain the wave data.

Wave directions can be converted from their current convention to a new convention by selecting [Station->Waves->Change Direction Convention] WWWL menu. The current convention will be selected on the from line when the dialog appears. Select the convention to convert to, and enter the [Local Azimuth of the New X Axis] then press [OK] to perform the conversion.

By selecting the appropriate choice from the Station->Waves menu, fixed values can be assigned to any field in the wave record.

You may also filter data using several filtering methods. See Filter Wave Data for more information.

Filter Wave DataWWWL allows you to filter wave data based on several criteria such as height range, period range or transport range. The height range, period range and propagation direction range filters are identical except for the variable they are based upon. The filter can be run in two modes, inclusive or exclusive. Inclusive mode affects all records that match the filter criteria, while exclusive mode affects the records that do not match. Records that fail the filter test have the action specified by the failure mode menu applied to them. By default all records that fail are removed from the editor, however a flag value [Flag Value] can be inserted into one of the fields of the record to mark it as failing without deleting the entire record. The filter range is specified by filling in the [Minimum] and [Maximum] fields with the desired variables.

The Transport Range filter computes the longshore sediment transport by each wave and removes or flags waves that have an insignificant transport rate. This filter is useful for performing GENESIS

simulations to remove waves events that will have no effect upon the result. By removing these events, the model will not waste time performing computations that are not useful.

To bring up the filter dialogs, switch to the Data tab. Right-click in the WWWL window. Select Waves, then select the corresponding range filter (Height, Period, Direction, or Transport).

Water Level Attributes and Procedures

Wind Attributes and Procedures Time Attributes NetCDF Files