Point statistics¶
Point statistics can be obtained by clicking in the map or by entering the longitude and latitude manually and clicking on “Show summary and charts” in the right panel. A choice of depth values is available. After a few seconds, a text summary and a set of charts appear in the right panel.
The text first gives some metadata on the position. Note that the reported position may differ slightly from the choosen, as it is from the center of a model grid cell. Thereafter it provides info on the current speed and the current velocity (speed and direction)
The scatter plot displays all current data from the position and depth, by eastwards and northwards components. It also displays an ellipsis with axes. The center of the ellipsis is the mean current. The axes show the directions of maximum and minimum variabilty, with the lengths showing the standard deviaton in the respective directions.
The time series simply show the time evolution of the east and north current components separately for the time period of the current archive. The blue curves give the “raw” hourly values while the red is smoothed by a xxx moving average. The horizontal lines shows the means.
The frequency plot is a histogram of current speed, irrespective of direction.
The tidal ellipses show the varying strength of the tidal current during a tidal cycle. Four of the major tidal consituents are displayed. The most important is usually the diurnal moon tide, M2.
The progressive vector diagram shows the time series of current, by placing the current vectors at the tip of the previous vector. It shows the virtual movement of a particle that experiences the current at the given position at all times.
If it is close to a straight line, the current has a stable direction.
The stick plot is an alternative way of depicting the current time series. It shows all current vectors with the footpoint moving uniformly along the time axis.
The current rose is basically a stacked histogram for the various directions. The length of the wedge for a given direction gives the frequency of current going that direction. The length of each coloured segment gives the frequency of current in that direction within the speed limits.