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Track Plot

The track plot data products are plots of latitude and longitude of horizontally mobile devices, usually Lagrangian ocean drifter buoys (small autonomous devices that float with the surface currents). Four formats are available, PNG and PDF static plots of the track, with the GIF and KML products provide dynamic and interactive displays.

Oceans 2.0 API filterdataProductCode=TP

Revision History

  1. 20180403: Initial release

Data Product Options

For Track Plot data products only
Raw Data

When this option is selected, raw data will be supplied in the data products: no action is taken to modify the data. In general, all scalar data is associated with a quality control flag. These flags are stored adjacent to the data values (not yet visible in the Track Plots). The plot titles will have "Raw Data" in their titles, the KML product will show "Raw Data" in the pop-up description.

Oceans 2.0 API filterdpo_qualityControl=1

Clean Data

Selecting this option will cause any data values with quality control failures (QAQC flags 3, 4 and 6) to be replaced with NaNs. Since the Track Plots (and all plots in general) can't plot NaNs, flagged / NaN'ed data is removed from the data products. Clean products have '-clean' in their file-name.

This is the default option for all data products.

Oceans 2.0 API filterdpo_qualityControl=0

File / Plot breaks: None (break on configuration changes or memory limits only)

This option controls if the time series is broken in to multiple files / plots. In this case, the Track Plots are only broken into multiply if nessecary for size / memory limits (~ 1 GB in memory) or if there's a configuration change or deployment.   

This is the default option for Track Plots.

Oceans 2.0 API filterdpo_filePlotBreaks=0

Plot breaks: Daily

When the plots are broken up daily, the plots will have "Daily Plot  # of #" in their title, the KML product will show "Daily Plot" in the pop-up description. The times in the file-names for Track Plots are the search time range of that plot, so these file-names will be different between the None and Daily options. 

Oceans 2.0 API filterdpo_filePlotBreaks=1


Formats

Track Plots are available in four formats: PNG and PDF track line plots, an animated GIF of those plots with a moving cursor to represent the drifter / device, and a KML file that creates a track plot with a time slider in Google Earth.

PNG / PDF

The PNG / PDF show the coastline from the Global Self-consistent, Hierarchical, High-resolution Geography Database (GSHHG), plotted using the m_map toolbox, with a line, start and end points.


Oceans 2.0 API filter: extension={png,pdf}

GIF

The animated GIF adds a red arrow cursor to the above plot showing the location and approximate heading at the time shown in the bottom of the plot. Depending on the time range plotted, up to 48 frames will be shown in the animation. Note that the frame rate is not fixed - the time per frame may be observed in the time stamps. Data gaps also affect the apparent speed of the cursor. 

 

Oceans 2.0 API filter: extension=gif

KML

KML files are a data file that works primarily with Google Earth. The file contains some metadata information and uses the "gx" object to plot the track with a time slider so that users can interrogate the position of the device / drifter over time. The drifter's position is labelled with it's device name and marked with a blue arrow, showing the drifters heading as users slide the time or use the playback function in the time slider. Start and End points are also shown. Clicking on the track, start or end pointson the map or in the places tree (on the left side) brings up a small text box that shows the precise times, the track will also show if it is clean or raw data and a daily file or not. Here is a screenshot of Google Earth on the desktop:

Here is a screenshot of Google Earth mobile. Note that the time slider functionality doesn't exist on mobile:

Oceans 2.0 API filter: extension=kml

Discussion

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