IntroductionTo plot a set of variables over a period of time:
- Choose a Start Time or the Track Real Time option. Track Real Time sets the start time to the current time minus Length
- Select a Time Zone
- Select a time Length with units
- Select one or more Variables, which may be organized under tab panels by variable type, site name, or alphabetically
- If provided, select one or more Stations
- Hit Plot
- The Track Real Time option is only enabled for projects that are on-going. When it is selected, data up to the current time will be plotted, covering the time Length, and your browser will poll the server for real-time updates.
- Use Back or Forward to page back or forward in time by Length. This will turn off Track Real Time
- When a Time Zone is selected, the Start Time will be adjusted to indicate the same moment in time. The time labels on the plot will be in the selected time zone.
- After changing a selection of variables, time or time zone, hit Plot to update the plot, as it is not automatically updated when a selection is made.
- To plot more than one dataset, open separate browser windows or tabs.
- 1-D Time Series Traces
- All selected variables with the same units will be plotted together.
- The sequence of plots is alphabetical by the name of the first variable in the plot.
- For all variables with the same units, the sequence in the legend will be alphabetical, by name.
- Click on a variable name in the legend at the top of a plot to toggle the visibility of the trace, and dynamically rescale the remaining traces.
- With a mouse, drag a rectangle on the plot to zoom in X and Y. Hit Reset Zoom to zoom back out.
- Use the sliders on the navigator trace below the chart to zoom in, and drag the selection to pan back and forth in time
- On phones, the navigator trace is not displayed. You can use a two-finger spread and pinch gesture to zoom in and out.
Plotting Aircraft Flight DataThe low-rate data from the NCAR GV and C130 are read from a real-time database on the ground, which is updated during a flight. If you're not sure of the start time of the most recent or the current flight, you can use a wide time selection by specifying a large time Length, for example 30 days, and a guess for the start time that is sufficiently early. Only the data found for the flight will be plotted. Select Track Real Time for an ongoing flight..
ISFS Sites and StationsFor ISFS projects, to identify the locations of measurements, a site suffix is typically appended to the variable name, such as "T.2m.abc" to indicate that the measurement was from site "abc". In order to provide a manageable way to select variables, NCharts will group the variables from each site under a separate tab.
For ISFS projects where a measurement is repeated at more than one site, with the same variable name, variables are stored in NetCDF form with a "station" dimension, and will not have a site suffix. For example: "T.2m". These variables will be provided under a "stations" tab, and checkboxes are provided for selecting one or more stations. The variable names will be shown on the plot with their station name.
Height vs Time DataIf a time series variable has a additional dimension, such as height or bin number, a color-coded heatmap time series will be plotted, with an associated color key.
- Heatmap Time Series
- The heatmap plots will be in alphabetical order, by variable name.
- To zoom in time and Y, drag a rectangle across the plot. A Reset zoom button will appear in the top right to zoom back out.
- The Y axis is the dimension index of the observations. If plotting a time-vs-height variable from a wind profiler, refer to the height variable to determine the height of the observation.
- When a Start Time and time Length are selected, the available soundings for that period are shown by their launch time in UTC.
- Choose one or more soundings, one or more X axis variables and a Y axis variable, typically alt or gpsalt. A profile will be plotted for each sounding selected.
- Currently 1000 points are plotted for each sounding.
- If the sonde reverses vertical direction, those points will not be shown.
- Click on a variable name in the legend at the bottom of a plot to toggle the visibility of a trace, and dynamically rescale the remaining traces.
- To zoom in X and Y, drag a rectangle on the plot with your mouse. A Reset zoom button will appear in the top right to zoom back out.
- To plot data as they arrive in near real-time, check Track Real Time, and select a time length for the plot. You do not need to enter a start time.
- This option is only enabled for projects that are on-going, and is not currently supported for soundings.
- Your browser will poll the server for new data, at a time interval equal to 1/2 the average time delta of the data, but not more frequently than every 10 seconds. The display will scroll down and and the start time will be updated when new data arrives.
- Real-time updates will fill in missing data for each variable back to the time of the previous non-missing value. If values previous to that time were updated by data processing, they will not be updated in the Ncharts display. Click on the Plot button to do a complete refresh.
- The "hamburger" icon at the top right of each plot is a print menu.
- Select Print chart to print on your local system, which may give you the option to plot to a PDF or PNG file.
- If you select one of the Download options, the plot will be sent to a Highcharts server for rendering and then made available for download. If the Highcharts servers are overloaded, a blank screen may result, in which case, try again later.
Bugs and Idiosyncracies
- If Track Real Time is selected, the window will scroll down to the top plot when an update arrives.
- Response will be slow if you ask for a large quantity of data. Data reduction and compression are not supported.
- Response of heatmap plots will be slower for variables with large dimensions. Choose a shorter period of time to improve the response, especially when plotting real-time data.
- Plots may not appear on the stock Android browser on old phones. The Chrome browser should work.
- On phones, enabling screen rotation, and plotting in horizontal mode will generally provide more readable plots.
- To scroll on phones, swipe on the right or left side to activate a small scrollbar. Scrolling response can be slow.
- If you return to plot a previous dataset, you may have to do a browser refresh to see the variables and time you selected previously.