Time-distance-variable scalar plots plot distance from a reference location versus time, colouring the plotted points with the value of the data. These plots are used for time-series scalar data from a single sensor on a mobile device, particularly one that moves on a repeating route, such as a ferry or a glider, for which the reference location is a terminal or deployment location. The positioning data may come from another device, such as a GPS, collocated with the requested sensor and device. As is done for all mobile scalar data, mobile position ancillary data is interpolated onto the requested sensor's time series, as further described here: Positioning and Attitude for Mobile Devices. Plots are normally broken into daily segments. Currently, these plots are only active for ferry data, so the daily plots are tuned to the ferry schedule. Daily plots show data from 12:00 UTC to 9:00 UTC the following day (this works out to 4 or 5 AM to 1 or 2 AM local time). As described in the data product options, users can also select a contiguous plot, which is intended to be used with 1-minute averaging to produce a plot of 1 month of data. If there are any QAQC flags to display, the plot will show them with the usual highlighting flag and an 'x' marker on the affected data point.
Oceans 3.0 API filter: dataProductCode=TDVSP
Time distance variable plots are available in PNG or PDF format. Below are three example PNG plots. First is a normal daily time-distance-variable plot. If a search covers multiple days, the daily plots will use the same plotting ranges, making comparisons much easier; the PDF product appends multiple plots together in a single, making scroll through the plots even easier. Second is an example of a 1-minute average time-distance-variable plot showing 5 days of data (normally one would want to show 1 month of data with a 1-minute average multi-day time-distance-variable plot). If there is no positioning data, but the requested sensor does have normal scalar data for the time range, the user will see an empty plot as shown in the last plot below:
Oceans 3.0 API filter: extension={png,pdf}
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