Plot day-light terminators and other sunlight parameters
gmt solar [ -B[p|s]parameters ] [ -C ] [ -G[fill] ] [ -I[lon/lat][+ddate][+zTZ] ] [ -Jparameters ] [ -M ] [ -N ] [ -Rregion ] [ -Tdcna[+ddate][+zTZ]] [ -U[stamp] ] [ -V[level] ] [ -Wpen ] [ -X[a|c|f|r][xshift] ] [ -Y[a|c|f|r][yshift] ] [ -bobinary ] [ -oflags ] [ -pflags ] [ -ttransp ] [ --PAR=value ]
solar calculates closed polygons for the day-night terminator and the civil, nautical and astronomical twilights and either writes them to standard output or uses them for clipping or filling on maps.
Formats the report selected by -I using tab-separated fields on a single line. The output is Sun Lon Lat Azimuth Elevation in degrees, Sunrise Sunset Noon in decimal days, day length in minutes, SolarElevationCorrected corrected for the effect of refraction index and Equation of time in minutes. Note that if no position is provided in -Ilon/lat the data after Elevation refers to the point (0,0).
- -G[fill] (more …)
Print current sun position as well as Azimuth and Elevation. Append lon/lat to print also the times of Sunrise, Sunset, Noon and length of the day. Add +ddate in ISO 8601 format, e.g, +d2000-04-25T04:52, to compute sun parameters for this date and time [Default is now]. If necessary, append a time zone via +zTZ. The time zone is given as an offset from UTC. Negative offsets look like −03:00 or −03. Positive offsets look like 02:00 or 02.
Write terminator(s) as a multisegment ASCII (or binary, see -bo) polygons to standard output. No plotting occurs.
Plot (or dump; see -M) one or more terminators defined via the dcna flags. Where: d means day/night terminator; c means civil twilight; n means nautical twilight; a means astronomical twilight. Add +ddate in ISO format, e.g, +d2000-04-25T12:15:00 to know where the day-night was at that date [Default is now]. If necessary, append time zone via +zTZ.
Refer to https://en.wikipedia.org/wiki/Twilight for definitions of different twilights.
- -W[pen] (more …)
Set pen attributes for lines or the outline of symbols [Defaults: width = default, color = black, style = solid].
- -borecord[+b|l] (more …)
Select native binary format for table output.
- -ocols[,…][,t[word]] (more …)
Select output columns (0 is first column; t is trailing text, append word to write one word only).
- -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0] (more …)
Select perspective view.
- -ttransp[/transp2] (more …)
Set transparency level(s) in percent.
- -^ or just -
Print a short message about the syntax of the command, then exit (Note: on Windows just use -).
- -+ or just +
Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exit.
- -? or no arguments
Print a complete usage (help) message, including the explanation of all options, then exit.
Temporarily override a GMT default setting; repeatable. See gmt.conf for parameters.
Note: Below are some examples of valid syntax for this module.
The examples that use remote files (file names starting with
can be cut and pasted into your terminal for testing.
Other commands requiring input files are just dummy examples of the types
of uses that are common but cannot be run verbatim as written.
Print current Sun position and Sunrise, Sunset times at given date, time and time zone:
gmt solar -I-7.93/37.079+d2016-02-04T10:01:00+z02:00
Plot the day-night and civil twilight:
gmt begin gmt coast -Rd -W0.1p -JQ0/14c -B -BWSen -Dl -A1000 gmt solar -W1p -Tdc gmt end show
Set up a clip path overlay based on the day/night terminator:
gmt solar -G -Tc
Code from the Excel Spreadsheets in http://www.esrl.noaa.gov/gmd/grad/solcalc/calcdetails.html
Taken from the NOAA site Data for Litigation note.
The NOAA Solar Calculator is for research and recreational use only. NOAA cannot certify or authenticate sunrise, sunset or solar position data. The U.S. Government does not collect observations of astronomical data, and due to atmospheric conditions our calculated results may vary significantly from actual observed values.
For further information, please see the U.S. Naval Observatory’s page Astronomical Data Used for Litigation