Climate (nearshore)

Nearshore climate means statistics on the 'normal' nearshore climate for the currently selected nearshore loaction (displayed in the header of the page). The climate screen lets you choose between various types of outputs available. It asks you to select

• The type of output (monthly distribution, histogram, scatter table 2D or 3D)
• The variable to show (wave height, wind speed or wave period)
• The part of the spectrum to use (for output wave parameters)
• The offshore data source (wave model or satellite; 3D scatter tables always use wave model data)
• The months of interest (applicable to histograms and scatter tables)

The type of output

A distribution over the months of the year can either be tabulated or plotted. The monthly distribution table gives the relative distribution of for instance wave height over all months of the year: January until December. The seasonality plot shows seasonal effects by means of monthly averages and their 90% confidence interval.

A histogram page consists of two tables and one plot. The tables show the probability of exceedance versus quantiles of the selected variable and vice versa. The plot visualizes the relative occurrence of the selected variable over classes.

A 2D scatter table shows the relative joint occurrence of two parameters. Each table entry contains the percentage or the absolute number of pairs of samples falling inside the related parameter classes. Colors indicate the highest entries.
You can plot of a directional wave or wind rose instead of the selected 2D scatter table by checking the designated box.
You can generate 13 (all year plus each month) 2D scatter tables at once by checking the 13x box. Checking this box will always result in 13 tables, despite any season selection at the top of the page.

A 3D scatter table shows one 2D scatter table of the selected pair of variables per directional sector or wind speed class.

The variable to show

Nearshore climate statistics are available for wave height and wave period. Wave height is significant wave height, wave period can be either the mean wave period or the zero-crossing wave period. Wind speed has not been translated to nearshore, but for convenience you can ask for offshore wind from this nearshore page. Wind speed is wind speed at 10m above sealevel.

The part of the spectrum

Wave parameters are found by integration of the 1D spectral energy density, given per frequency bin. Integration is commonly done over the full frequency range, leading to total significant wave height or wave period. Height and period of longer swell waves are found by integrating the lower frequencies, referred to as the swell part of the spectrum. Shorter waves, generated by the local wind, get their energy from the higher frequency bins, referred to as the wind sea part of the spectrum. Waveclimate.com uses a nearly fully developed (wave age is set to 1.1) Donelan-Pearson spectrum to model the wind sea part of a spectrum. After substracting this wind sea spectrum from the total spectrum, the swell spectrum remains.

The offshore data source

Almost all types of waveclimate.com output offer the option to switch between two different data sources: climate statistics can either be based on wave model data or satellite data. Statistics cover almost 20 years of satellite data (starting in 1985) or 13 years (starting in 1992) of model data. Wave model statistics are based on 3-hourly timeseries taken from the current grid point, being the grid point nearest to the current location. Satellite data comes from various satellite-sensor combinations and is taken from the currently selected area, typically 200 km wide. As a satellite passes once every few days, the amount of satellite data is significantly smaller than the amount of model data. On the other hand, satellite data has a better spatial coverage. The amount of data needed for 3D scatter tables rules out satellites as data source.

We advise you to use the model as primary data source for 'normal' nearshore climate statistics.

The months of interest

One or more specific months of interest can be selected to investigate seasonal variations in the nearshore climate. Typically, one may want to select the months of a particular season. If you do not know which months to choose, a monthly distribution may be helpful.

Tip: Logon as demo (no password needed) to get acquainted with the different types of output without being charged.

Tip: Use preferences to tailor the output to your needs (under Account in the upper right menu) .