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Offshore

Location Climate Monthly statistics Histogram Scatter table 2D Directional rose Scatter table 3D Persistency Coverage of windows Number of windows Delay until next window Data of Past Events Timeseries plot Vector map Timeseries download Quick Stats

Near Shore

Location simple model Seabed profile Location ray model Climate Monthly statistics Histogram Scatter table 2D Directional rose Scatter table 3D Persistency Coverage of windows Number of windows Delay until next window Timeseries download

Offshore location

The location selection screen is meant for selection of the offshore datasource for both satellite and wave model data. Satellite observations are selected by means of an offshore data area while wave model results will be retrieved from the selected gridpoint.

Navigating around the globe can be started by clicking anywhere inside the default (global) map. Alternatively, one can set the center of the new area by entering a longitude-latitude pair. Setting zoom in/out allows zooming into the new location or zooming out of the current location. The system answers to zoom actions by plotting the newly selected area. A (more) detailed map is used as soon as the plot area reaches a certain minimum size. The size of the data selection area can be set. In addition, one may choose the kind of chart used while navigating . When using the chart "wave model gridpoints" as background, the system shows all available wave model output points and marks the currently selected gridpoint, that is the gridpoint nearest to the center of the area of interest. No gridpoint will be selected if the distance between the centre of the area and the nearest gridpoint exceeds 400km. At any time, one can return to the (initial) global map.

In the plot, two rectangular areas are drawn : one to be used for the altimeter and scatterometer (black solid line) and one for the SAR (black dashed line). We decided to enlarge the area for retrieval of SAR data, because the number of SAR samples is (relatively) small.

User Controls

Name	Type	Default	Description
Longitude & latitude	Editabletext fields for degrees and minutes. Pull down list for selection of the hemisphere	0 - 0 - East 0 - 0 - North	The co-ordinate pair of the center of the current area.. Please enter longitude as degrees from [0,180> and minutes from [0,60>. Additionally, select the Eastern or Western hemisphere. Enter latitude as degrees from [0,90> and minutes from [0,60> and choose North or South. Re-draw the map around the new center by pushing the "Update map" button. The wave model gridpoint nearest to the center of the current area will become the current gridpoint as long as the distance between the center of the area and the gridpoint does not exceed 400km.
Zoom in/out	Pull down list	Zoom in	Zoom into the new area or zoom out of the current area. The system uses a zoom factor of 2. This zoom factor defines the size of the new data area (not the size of the entire plot) to be drawn next, relative to the size of the current data area. Opting "Zoom in" will result in a data area twice as small. Using "Unchanged" will keep the size of the data area unchanged (you might want to re-define the center of the area to move around the globe). The system may adjust the zoom factor in order to prevent parts of the area plot to fall outside the [90S,90N] latitude range. Longitudes are cyclic.
View chart of	Pull down list	Presence of altimeter data	You may choose one of the available charts to be used while navigating to your area / gridpoint of interest.
Size of the data area	Pull down list	200 km	The size of the area from within which satellite data will be used. The system will multiplicate this area size by an internal factor, depending on the kind of satellite sensor in order to get enough samples : 1 for Altimeter and Scatterometer and 2 for SAR. In addition, the area used to retrieve SAR spectra will never be less than 200 km. This is done because the number of SAR samples is relatively small.
Update map	Push button		Re-draws the area plot according to the values of the controls above.
Reset	Push button		Re-draws the initial global chart and re-installs the defaults.
OK	Push button		If the user is certain about the selected area / gridpoint, he sends off the area / gridpoint selection form to interrogate the database. Assuming that the user selected a location at which, according to the data mask, data is said to be present, the system will present the choice between the event branch and the climate branch. Both satellite data (inside the area of interest) and wave model data (from the selected gridpoint) are extracted from the database and will become available for use later on.
Quick Stats	Push button		Pushing this button will take you to the Quick Offshore Statistics input screen. The quick statistics input screen enables you to quickly retrieve a summary of the wind and wave climate at up to 10 offshore locations in one go. All scatter tables wil be written to one HTML result page and one downloadable comma-seperated-values text file.

Background charts available

The spatial plot centered around the selected model point and data area under investigation shows coast lines and uses one of the following maps as background.

(all models)

• Gridpoints of all models (Global, EU-shelf, Mediterranean)

(satellite)

• Presence of altimeter data (the default, also referred to as data mask)
• Data density altimeter
• Data density scatterometer
• Data density SAR

(satellite-based average parameters)

• Wave height altimeter
• Wind speed altimeter
• Wind speed scatterometer (vectors)
• Wave height SAR (vectors)
• Wave height swell SAR (vectors)
• Wave height wind sea SAR (vectors)
• Wave period SAR
• Wave period swell SAR
• Wave period wind sea SAR

(model-based average parameters)

• Wave height global model (vectors)
• Wind speed global model (vectors)
• Wave period global model

Wave model gridpoints :

The output points of all wave model grids are shown. The resolution of the global output grid is 1x1 degrees on open ocean and 0.5x0.5 degree in coastal zones of about 150km wide. Near the coast, the resolution of the local Mediterranean model is 1/4 degree and the EU-shelf grid mesh size is 1/6 degree. On open sea the resolution of the two regional grids is 0.5x0.5 degrees. The currently selected gridpoint is marked (blue color). No wave model gridpoint will be selected if the distance between the centre of the data area and the nearest gridpoint exceeds 400 km.

Presence of altimeter data :

A vital aspect is the availability of satellite data. Inside the maps the shaded (orange) areas indicate the presence (i.e. at least 200 samples) of satellite data in the database. One can expect data to be present, as long as some part of the data area shown has been shaded. The data mask is based on the number of samples from ERS1-, ERS2-, Topex/Poseidon- , Geosat-, GFO- and Jason-1 altimeter. The grid consists of square longitude-latitude cells of half a degree.

Data density :

Data density maps show the distribution of samples taken over the globe. Note that the numbers to the right represent the total number of samples per square of half a degree. Near the equator, the number of samples inside a typical 200 km x 200 km area (~ 2 x 2 degrees) can be estimated by multiplying the data density number by approximately 16. Also note that the number of SAR samples is far less than the number of altimeter and scatterometer samples. For this reason, we take the SAR samples from the enlarged area (black dashed line).

Wave height altimeter :

A global distribution of average significant wave height, based on altimeter observations in the database. Mind that the colored areas in this chart do not ensure the availability of data. They only indicate the wave height classes.

Wind speed altimeter :

A global distribution of average wind speed, based on altimeter observations in the database.

Wind speed scatterometer :

A global vector field of average wind speed and wind direction, based on scatterometer observations in the database.

Wave height swell SAR :

A global vector field of average swell, based on the swell part ERS-SAR spectra in the database. Only cells containing at least 5 samples are shown.

Wave height wind sea SAR :

A global vector field of average wind sea, based on the wind sea part of ERS-SAR spectra in the database. Only cells containing at least 5 samples are shown.

Wave period SAR :

A global distribution of average wave period, based on ERS-SAR observations in the database. Average period is Tm-10, derived from the total spectrum. Only cells containing at least 5 samples are shown.

Wave period swell SAR :

A global distribution of average swell period, based on ERS-SAR observations in the database. Average period is Tm-10, derived from the swell part of the spectrum. Only cells containing at least 5 samples are shown.

Wave period wind sea SAR :

A global distribution of average wind sea period, based on ERS-SAR observations in the database. Average period is Tm-10, derived from the wind sea part of the spectrum. Only cells containing at least 5 samples are shown.

Wave height global model :

A global model-based vector field of average significant wave height, with 1.25x1 degree resolution.

Wind speed global model :

A global model-based vector field of average 1-hour averaged wind speed at 10m above the surface, with 1.25x1 degree resolution.

Wave period global model :

A global model-based distribution of average wave period Tm-10, with 1.25x1 degree resolution.