skewt-js

Plot a skew-T log-P diagram based on sounding data.

This was forked from: https://github.com/dfelix/skewt-js.

Changes

• By now LOTS.
• Updated to work with D3 version 5.
• A treeshaken D3 is now bundled into bundle.js, no need to load it.
• Interactivity: Set top pressure (zoom), set gradient, set parcel temperature, toggle maintain temperature range.
• Highlight different lines.

I have added the following functionality thanks to Victor Berchet :

• Added moist adiabats.
• Added isohumes.
• Added parcel trajectory.

Added calculations for TCON, LCL, CCL, Thermal top and cloud Top. Lines to indicate these parameters can be toggled.

How to use

<link rel="stylesheet" href="dist/skewt.css">

<script src="dist/bundle.js"></script>

Ensure you create a div using a specified id (ex: id="mySkewt") and class = "skew-t"

<div id="mySkewt" class="skew-t"></div>

Declare a new SkewT var passing the css selector for the placeholder.

var skewt = new SkewT('#mySkewt' , options);

SkewT currently only contains methods:

Plot

.plot(array, plotOptions) will plot dew point and air temperature lines and wind barbs. options is optional.

Available options:

plotOptions = {
	add:true, // to add a plotline,  else the current ones will be cleared. 
  	select:true, // added plot line will be highlighted,  relevant if >1.
	max: 2// maximum number of plots superimposed,  if max reached,  last one will be overwritten,
	ixShift: 1// moves the windbarbs and clouds to the right, ( I use it in windy to differentiate between sonde data and forecast data )
}

  var skewt = new SkewT('#mySkewt');
  var sounding = [];
  skewt.plot(sounding, plotOptions);

Expected array format should follow the GSD Sounding Format.

[{
		"press": 1000.0,  // pressure in whole millibars
		"hght": 173.0,    // height in meters (m)
		"temp": 14.1,     // temperature in degrees Celsius
		"dwpt": 6.5,      // dew point temperature in degree Celsius
		"wdir": 8.0,      // wind direction in degrees
		"wspd": 6.173     // wind speed in meters per second (m/s)
	}, {
		"press": 975.0,
		"hght": 386.0,
		"temp": 12.1,
		"dwpt": 5.6,
		"wdir": 10.0,
		"wspd": 7.716
	},
	...
]

Clear

.clear() will clear the previous plot lines and wind barbs.

Select a skewt plot

.selectSkewt( array_previously_sent_with_plot ) to highlight a plot lines. The tooltips will then display info from this line.

Remove a specific plot, leave the others:

.removePlot //remove a specific plot, referenced by data object passed initially.

Parcel trajectory calculations can be done, without actually plotting it:

.parcelTrajectory(
	{temp,  gh,  level},  //arrays,  must be same length
	steps,  // integer
	surface_temp,  surface_pressure, surface_dewpoint
)

set or get Params

.setParams(
	{
		height,  //in pixels 
		topp,  //top pressure
		parctempShift,  //default parcel temperature offset  
		parctemp,  
		basep, 
		steph,  //step height  
		gradient //in degrees 
	}
)
.getParams();

Tooltips:

.move2P, .hideTooltips and .showTooltips

Listener

.on(event, callback);

Possible events:

• press, //when tooltip is moved.
• parctemp, topp, parctempShift, gradient; //when any of the ranges are moved