GMTDEFAULTS

gmtdefaults − To list current GMT defaults

gmtdefaults −D[u|s] | −L

gmtdefaults lists the GMT parameter defaults if the option −D is used. There are three ways to change some of the settings: (1) Use the command gmtset, (2) use any texteditor to edit the file .gmtdefaults4 in your home or current directory (if you do not have this file, run gmtdefaults -D > ~/.gmtdefaults4 to get one with the system default settings), or (3) overrid any parameter by specifying one or more −−PARAMETER=VALUE statements on the commandline of any GMT command (PARAMETER and VALUE are any combination listed below). The first two options are permanent changes until explicitly changed back, while the last option is emphemeral and only applies to the single GMT command that received the override. GMT can provide default values in US or SI units. This choice is determined by the contents of the gmt.conf file in GMT’s share directory.

−D

Print the system GMT defaults to standard output. Append u for US defaults or s for SI defaults. [−D alone gives current choice in gmt.conf].

−L

Print the user’s currently active defaults to standard output.

Your currently active defaults come from the .gmtdefaults4 file in the current working directory, if present; else from the .gmtdefaults4 file in your home directory, if present; else from the system defaults set at the time GMT was compiled.

The following is a list of the parameters that are user-definable in GMT. The parameter names are always given in UPPER CASE. The parameter values are case-insensitive unless otherwise noted. The system defaults are given in brackets [ for SI (and US) ]. Those marked * can be set on the command line as well (the corresponding option is given in parentheses). Note that default distances and lengths below are given in both cm or inch; the chosen default depends on your choice of default unit (see MEASURE_UNIT). You can explicitly specify the unit used for distances and lengths by appending c (cm), i (inch), m (meter), or p (points). When no unit is indicated the value will be assumed to be in the unit set by MEASURE_UNIT. Note that the printer resolution DOTS_PR_INCH is always the number of dots or pixels per inch. Several parameters take only TRUE or FALSE.

ANNOT_MIN_ANGLE

If the angle between the map boundary and the annotation baseline is less than this minimum value (in degrees), the annotation is not plotted (this may occur for certain oblique projections.) Give a value in the range 0−90. [20]

ANNOT_MIN_SPACING

If an annotation would be plotted less than this minimum distance from its closest neighbor, the annotation is not plotted (this may occur for certain oblique projections.) [0]

ANNOT_FONT_PRIMARY

Font used for upper annotations, etc. [Helvetica]. Specify either the font number or the font name (case sensitive!). The 35 available fonts are:

0 Helvetica

1 Helvetica-Bold

2 Helvetica-Oblique

3 Helvetica-BoldOblique

4 Times-Roman

5 Times-Bold

6 Times-Italic

7 Times-BoldItalic

8 Courier

9 Courier-Bold

10 Courier-Oblique

11 Courier-BoldOblique

12 Symbol

13 AvantGarde-Book

14 AvantGarde-BookOblique

15 AvantGarde-Demi

16 AvantGarde-DemiOblique

17 Bookman-Demi

18 Bookman-DemiItalic

19 Bookman-Light

20 Bookman-LightItalic

21 Helvetica-Narrow

22 Helvetica-Narrow-Bold

23 Helvetica-Narrow-Oblique

24 Helvetica-Narrow-BoldOblique

25 NewCenturySchlbk-Roman

26 NewCenturySchlbk-Italic

27 NewCenturySchlbk-Bold

28 NewCenturySchlbk-BoldItalic

29 Palatino-Roman

30 Palatino-Italic

31 Palatino-Bold

32 Palatino-BoldItalic

33 ZapfChancery-MediumItalic

34 ZapfDingbats

ANNOT_FONT_SIZE_PRIMARY

Font size (> 0) in points for map annotations. [14]

ANNOT_FONT_SECONDARY

Font to use for time axis secondary annotations. See ANNOT_FONT_PRIMARY for available fonts [Helvetica].

ANNOT_FONT_SIZE_SECONDARY

Font size (> 0) for time axis secondary annotations in points [16].

ANNOT_OFFSET_PRIMARY

Distance from end of tickmark to start of annotation [0.2c (or 0.075i)]. A negative offset will place the annotation inside the map border.

ANNOT_OFFSET_SECONDARY

Distance from base of primary annotation to the top of the secondary annotation [0.2c (or 0.075i)] (Only applies to time axes with both primary and secondary annotations).

BASEMAP_AXES

Sets which axes to draw and annotate. Case sensitive: Upper case means both draw and annotate, lower case means draw axis only. [WESN].

BASEMAP_FRAME_RGB

Color used to draw map boundaries and annotations. Give a red/green/blue triplet, with each element in the 0−255 range. Prepend ’+’ to replicate this color to the tick-, grid-, and frame-pens. [0/0/0] (black).

BASEMAP_TYPE

Choose between plain and fancy (thick boundary, alternating black/white frame; append + for rounded corners) [fancy]. For some map projections (e.g., Oblique Mercator), plain is the only option even if fancy is set as default. In general, fancy only applies to situations where the projected x and y directions parallel the lon and lat directions (e.g., rectangular projections, polar projections).

CHAR_ENCODING

Names the eight bit character set being used for text in files and in command line parameters. This allows GMT to ensure that the PostScript output generates the correct characters on the plot.. Choose from Standard, Standard+, ISOLatin1, ISOLatin1+, and ISO-8859-x (where x is in the ranges 1-10 or 13-15). See Appendix F for details [ISOLatin1+ (or Standard+)].

COLOR_BACKGROUND

Color used for the background of images (i.e., when z < lowest colortable entry). Give a red/green/blue triplet, with each element in the 0−255 range. [0/0/0] (black)

COLOR_FOREGROUND

Color used for the foreground of images (i.e., when z > highest colortable entry). Give a red/green/blue triplet, with each element in the 0−255 range. [255/255/255] (white)

COLOR_IMAGE

Selects which operator to use when rendering bit-mapped color images. Due to the lack of the colorimage operator in some PostScript implementations, GMT offers 2 different options:

adobe (Adobe’s colorimage definition) [Default].

tiles (Plot image as many individual rectangles).

COLOR_MODEL

Selects if color palette files contain RGB values (r,g,b in 0-255 range), HSV values (h in 0-360, s,v in 0-1 range), or CMYK values (c,m,y,k in 0-100% range). A COLOR_MODEL setting in the color palette file will override this setting. Internally, color interpolation takes place directly on the rgb values which can give unexpected hues, whereas interpolation directly on the hsv values better preserves the hues. Prepend the prefix "+" to force interpolation in the selected color system (does not apply to the CMYK system) [rgb].

COLOR_NAN

Color used for the non-defined areas of images (i.e., where z == NaN). Give a red/green/blue triplet, with each element in the 0−255 range. [128/128/128] (gray)

D_FORMAT

Output format (C language printf syntax) to be used when printing double precision floating point numbers. For geographic coordinates, see OUTPUT_DEGREE_FORMAT. [%lg].

DEGREE_SYMBOL

Determines what symbol is used to plot the degree symbol on geographic map annotations. Choose between ring, degree, colon, or none [ring].

DOTS_PR_INCH

Resolution of the plotting device (dpi). Note that in order to be as compact as possible, GMT PostScript output uses integer formats only so the resolution should be set depending on what output device you are using. E.g, using 300 and sending the output to a Linotype 300 phototypesetter (2470 dpi) will not take advantage of the extra resolution (i.e., positioning on the page and line thicknesses are still only done in steps of 1/300 inch; of course, text will look smoother) [300].

ELLIPSOID

The (case sensitive) name of the ellipsoid used for the map projections [WGS-84]. Choose among

WGS-84

1984

World Geodetic System [Default]

OSU91A

1991

Ohio State University

OSU86F

1986

Ohio State University

Engelis

1985

Goodard Earth Models

SGS-85

1985

Soviet Geodetic System

MERIT-83

1983

United States Naval Observatory

GRS-80

1980

International Geodetic Reference System

Hughes-1980

1980

Hughes Aircraft Company for DMSP SSM/I grid products

Lerch

1979

For geoid modelling

ATS77

1977

Average Terrestrial System, Canada Maritime provinces

IAG-75

1975

International Association of Geodesy

Indonesian

1974

Applies to Indonesia

WGS-72

1972

World Geodetic System

NWL-10D

1972

Naval Weapons Lab (Same as WGS-72)

South-American

1969

Applies to South America

Fischer-1968

1968

Used by NASA for Mercury program

Modified-Mercury-1968

1968

Same as Fischer-1968

GRS-67

1967

International Geodetic Reference System

International-1967

1967

Worldwide use

WGS-66

1966

World Geodetic System

NWL-9D

1966

Naval Weapons Lab (Same as WGS-66)

Australian

1965

Applies to Australia

APL4.9

1965

Appl. Physics

Kaula

1961

From satellite tracking

Hough

1960

Applies to the Marshall Islands

WGS-60

1960

World Geodetic System

Fischer-1960

1960

Used by NASA for Mercury program

Mercury-1960

1960

Same as Fischer-1960

Modified-Fischer-1960

1960

Applies to Singapore

Fischer-1960-SouthAsia

1960

Same as Modified-Fischer-1960

Krassovsky

1940

Used in the (now former) Soviet Union

War-Office

1926

Developed by G. T. McCaw

International-1924

1924

Worldwide use

Hayford-1909

1909

Same as the International 1924

Helmert-1906

1906

Applies to Egypt

Clarke-1880

1880

Applies to most of Africa, France

Clarke-1880-Arc1950

1880

Modified Clarke-1880 for Arc 1950

Clarke-1880-IGN

1880

Modified Clarke-1880 for IGN

Clarke-1880-Jamaica

1880

Modified Clarke-1880 for Jamaica

Clarke-1880-Merchich

1880

Modified Clarke-1880 for Merchich

Clarke-1880-Palestine

1880

Modified Clarke-1880 for Palestine

Andrae

1876

Applies to Denmark and Iceland

Clarke-1866

1866

Applies to North America, the Philippines

Clarke-1866-Michigan

1866

Modified Clarke-1866 for Michigan

Struve

1860

Friedrich Georg Wilhelm Struve

Clarke-1858

1858

Clarke’s early ellipsoid

Airy

1830

Applies to Great Britain

Airy-Ireland

1830

Applies to Ireland in 1965

Modified-Airy

1830

Same as Airy-Ireland

Bessel

1841

Applies to Central Europe, Chile, Indonesia

Bessel-Schwazeck

1841

Applies to Namibia

Bessel-Namibia

1841

Same as Bessel-Schwazeck

Bessel-NGO1948

1841

Modified Bessel for NGO 1948

Everest-1830

1830

India, Burma, Pakistan, Afghanistan, Thailand

Everest-1830-Kalianpur

1830

Modified Everest for Kalianpur (1956)

Everest-1830-Kertau

1830

Modified Everest for Kertau, Malaysia & Singapore

Everest-1830-Timbalai

1830

Modified Everest for Timbalai, Sabah Sarawak

Everest-1830-Pakistan

1830

Modified Everest for Pakistan

Walbeck

1819

First least squares solution by Finnish astronomer

Plessis

1817

Old ellipsoid used in France

Delambre

1810

Applies to Belgium

CPM

1799

Comm. des Poids et Mesures, France

Maupertius

1738

Really old ellipsoid used in France

Sphere

1980

The mean radius in GRS-80 (for spherical/plate tectonics applications)

Note that for some global projections, GMT may default to GRS-80 Sphere regardless of ellipsoid actually chosen. A warning will be given when this happens. If a different ellipsoid name than those mentioned here is given, GMT will attempt to open a file with that name in the current directory, and read a single record that contains the ellipsoid name, year, major-axis (in m), minor-axis (in m), and flattening (f) from the first record, where the fields must be separated by white-space (not commas). This way a custom ellipsoid (e.g., those used for other planets) may be used. A negative flattening means GMT will recalculate flattening from the two radii.

FIELD_DELIMITER

This setting determines what character will separate ASCII output data columns written by GMT. Choose from tab, space, comma, and none [tab].

FRAME_PEN

Thickness of pen used to draw plain map frame in dpi units or points (append p) [1.25p].

FRAME_WIDTH

Width (> 0) of map borders for fancy map frame [0.2c (or 0.075i)].

GLOBAL_X_SCALE

Global x-scale (> 0) to apply to plot-coordinates before plotting. Normally used to shrink the entire output down to fit a specific height/width [1.0].

GLOBAL_Y_SCALE

Same, but for y-coordinates [1.0].

GRID_CROSS_SIZE_PRIMARY

Size (>= 0) of grid cross at lon-lat intersections. 0 means draw continuous gridlines instead [0].

GRID_PEN_PRIMARY

Pen thickness used to draw grid lines in dpi units or points (append p) [0.25p].

GRID_CROSS_SIZE_SECONDARY

Size (>= 0) of grid cross at secondary lon-lat intersections. 0 means draw continuous gridlines instead [0].

GRID_FORMAT

Default file format for grids, with optional scale, offset and invalid value, written as ff/scale/offset/invalid. The 2-letter format indicator can be one of [bcnsr][bsifd]. The first letter indicates native GMT binary, old format NetCDF, COARDS-compliant NetCDF, Surfer format or Sun Raster format. The second letter stands for byte, short, int, float and double, respectively. When /invalid is omitted the appropriate value for the given format is used (NaN or largest negative). When /scale/offset is omitted, /1.0/0.0 is used. [nf].

GRID_PEN_SECONDARY

Pen thickness used to draw grid lines in dpi units or points (append p) [0.5p].

GRIDFILE_SHORTHAND

If TRUE, all gridfile names are examined to see if they use the file extension shorthand discussed in Section 4.17 of the GMT Technical Reference and Cookbook. If FALSE, no filename expansion is done [FALSE].

HEADER_FONT

Font to use when plotting headers. See ANNOT_FONT_PRIMARY for available fonts [Helvetica].

HEADER_FONT_SIZE

Font size (> 0) for header in points [36].

HEADER_OFFSET

Distance from top of axis annotations (or axis label, if present) to base of plot header [0.5c (or 0.1875i)].

HISTORY

If TRUE, passes the history of past common command options via the hidden .gmtcommands4 file [TRUE].

HSV_MIN_SATURATION

Minimum saturation (0−1) assigned for most negative intensity value [1.0].

HSV_MAX_SATURATION

Maximum saturation (0−1) assigned for most positive intensity value [0.1].

HSV_MIN_VALUE

Minimum value (0−1) assigned for most negative intensity value [0.3].

HSV_MAX_VALUE

Maximum value (0−1) assigned for most positive intensity value [1.0].

INPUT_CLOCK_FORMAT

Formatting template that indicates how an input clock string is formatted. This template is then used to guide the reading of clock strings in data fields. To properly decode 12-hour clocks, append am or pm (or upper case) to match your data records. As examples, try hh:mm, hh:mm:ssAM, etc. [hh:mm:ss].

INPUT_DATE_FORMAT

Formatting template that indicates how an input date string is formatted. This template is then used to guide the reading of date strings in data fields. You may specify either Gregorian calendar format or ISO week calendar format. Gregorian calendar: Use any combination of yyyy (or yy for 2-digit years; if so see Y2K_OFFSET_YEAR), mm (or o for abbreviated month name in the current time language), and dd, with or without delimiters. For day-of-year data, use jjj instead of mm and/or dd. Examples can be ddmmyyyy, yy-mm-dd, dd-o-yyyy, yyyy/dd/mm, yyyy-jjj, etc. ISO Calendar: Expected template is yyyy[-]W[-]ww[-]d, where ww is ISO week and d is ISO week day. Either template must be consistent, e.g., you cannot specify months if you don’t specify years. Examples are yyyyWwwd, yyyy-Www, etc. [yyyy-mm-dd].

INTERPOLANT

Determines if linear (linear), Akima’s spline (akima), or natural cubic spline (cubic) should be used for 1-D interpolations in various programs [akima].

IO_HEADER

(* −H) Specifies whether input/output ASCII files have header record(s) or not [FALSE].

N_HEADER_RECS

Specifies how many header records to expect if −H is turned on [1].

LABEL_FONT

Font to use when plotting labels below axes. See ANNOT_FONT_PRIMARY for available fonts [Helvetica].

LABEL_FONT_SIZE

Font size (> 0) for labels in points [24].

LABEL_OFFSET

Distance from base of axis annotations to the top of the axis label [0.3c (or 0.1125i)].

LINE_STEP

Determines the maximum length (> 0) of individual straight line-segments when drawing arcuate lines [0.025c (or 0.01i)]

MAP_SCALE_FACTOR

Changes the default map scale factor used for the Polar Stereographic [0.9996], UTM [0.9996], and Transverse Mercator [1] projections in order to minimize areal distortion. Provide a new scale-factor or leave as default.

MAP_SCALE_HEIGHT

Sets the height (> 0) on the map of the map scale bars drawn by various programs [0.2c (or 0.075i)].

MEASURE_UNIT

Sets the unit length. Choose between cm, inch, m, and point. [cm]. Note that, in GMT, one point is defined as 1/72 inch (the PostScript definition), while it is often defined as 1/72.27 inch in the typesetting industry. There is no universal definition.

N_COPIES

(* −c) Number of plot copies to make [1].

OBLIQUE_ANNOTATION

This integer is a sum of 6 bit flags (most of which only are relevant for oblique projections): If bit 1 is set (1), annotations will occur wherever a gridline crosses the map boundaries, else longitudes will be annotated on the lower and upper boundaries only, and latitudes will be annotated on the left and right boundaries only. If bit 2 is set (2), then longitude annotations will be plotted horizontally. If bit 3 is set (4), then latitude annotations will be plotted horizontally. If bit 4 is set (8), then oblique tickmarks are extended to give a projection equal to the specified tick_length. If bit 5 is set (16), tickmarks will be drawn normal to the border regardless of gridline angle. If bit 6 is set (32), then latitude annotations will be plotted parallel to the border. To set a combination of these, add up the values in parentheses. [1].

OUTPUT_CLOCK_FORMAT

Formatting template that indicates how an output clock string is to be formatted. This template is then used to guide the writing of clock strings in data fields. To use a floating point format for the smallest unit (e.g. seconds), append .xxx, where the number of x indicates the desired precision. If no floating point is indicated then the smallest specified unit will be rounded off to nearest integer. For 12-hour clocks, append am, AM, a.m., or A.M. (GMT will replace a|A with p|P for pm). If your template starts with a leading hyphen (-) then each integer item (y,m,d) will be printed without leading zeros (default uses fixed width formats). As examples, try hh:mm, hh.mm.ss, hh:mm:ss.xxxx, hha.m., etc. [hh:mm:ss].

OUTPUT_DATE_FORMAT

Formatting template that indicates how an output date string is to be formatted. This template is then used to guide the writing of date strings in data fields. You may specify either Gregorian calendar format or ISO week calendar format. Gregorian calendar: Use any combination of yyyy (or yy for 2-digit years; if so see Y2K_OFFSET_YEAR), mm (or o for abbreviated month name in the current time language), and dd, with or without delimiters. For day-of-year data, use jjj instead of mm and/or dd. As examples, try yy/mm/dd, yyyy=jjj, dd-o-yyyy, dd-mm-yy, yy-mm, etc. ISO Calendar: Expected template is yyyy[-]W[-]ww[-]d, where ww is ISO week and d is ISO week day. Either template must be consistant, e.g., you cannot specify months if you don’t specify years. As examples, try yyyyWww, yy-W-ww-d, etc. If your template starts with a leading hyphen (-) then each integer item (y,m,d) will be printed without leading zeros (default uses fixed width formats) [yyyy-mm-dd].

OUTPUT_DEGREE_FORMAT

Formatting template that indicates how an output geographical coordinate is to be formatted. This template is then used to guide the writing of geographical coordinates in data fields. The template is in general of the form [+|-]D or [+|-]ddd[:mm[:ss]][.xxx][F]. The various terms have the following purpose:

+

means output longitude in the 0 to 360 range [-180/+180]

-

means output longitude in the -360 to 0 range [-180/+180]

D

Use D_FORMAT for floating point degrees.

ddd

Fixed format integer degrees

:

delimiter used

mm

Fixed format integer arc minutes

ss

Fixed format integer arc seconds

F

Encode sign using WESN suffix

The default is +D.

PAGE_COLOR

Sets the color of the imaging background, i.e., the paper. Give a red/green/blue triplet, with each element in the 0−255 range. [255/255/255] (white).

PAGE_ORIENTATION

(* −P) Sets the orientation of the page. Choose portrait or landscape [landscape].

PAPER_MEDIA

Sets the physical format of the current plot paper [A4]. The following formats (and their widths and heights in points) are recognized (Additional site-specific formats may be specified in the gmtmedia.d file in $GMTHOME/share; see that file for details):

Media

width

height

A0

2380

3368

A1

1684

2380

A2

1190

1684

A3

842

1190

A4

595

842

A5

421

595

A6

297

421

A7

210

297

A8

148

210

A9

105

148

A10

74

105

B0

2836

4008

B1

2004

2836

B2

1418

2004

B3

1002

1418

B4

709

1002

B5

501

709

archA

648

864

archB

864

1296

archC

1296

1728

archD

1728

2592

archE

2592

3456

flsa

612

936

halfletter

396

612

note

540

720

letter

612

792

legal

612

1008

11x17

792

1224

ledger

1224

792

For a completely custom format (e.g., for large format plotters) you may also specify Custom_WxH, where W and H are in points. To force the printer to request a manual paper feed, append ’-’ to the media name, e.g., A3- will require the user to insert a A3 paper into the printer’s manual feed slot. To indicate you are making an EPS file, append ’+’ to the media name. Then, GMT will attempt to issue a tight bounding box [Default Bounding Box is the paper dimension].

PLOT_CLOCK_FORMAT

Formatting template that indicates how an output clock string is to be plotted. This template is then used to guide the formatting of clock strings in plot annotations. See OUTPUT_CLOCK_FORMAT for details. [hh:mm:ss].

PLOT_DATE_FORMAT

Formatting template that indicates how an output date string is to be plotted. This template is then used to guide the plotting of date strings in data fields. See OUTPUT_DATE_FORMAT for details. In addition, you may use a single o instead of mm (to plot month name) and u instead of W[-]ww to plot "Week ##". Both of these text strings will be affected by the TIME_LANGUAGE setting. [yyyy-mm-dd].

PLOT_DEGREE_FORMAT

Formatting template that indicates how an output geographical coordinate is to be plotted. This template is then used to guide the plotting of geographical coordinates in data fields. See OUTPUT_DEGREE_FORMAT for details. In addition, you can append A which plots the absolute value of the coordinate. The default is +ddd:mm:ss. Not all items may be plotted as this depends on the annotation interval.

POLAR_CAP

Controls the appearance of gridlines near the poles for all azimuthal projections and a few others in which the geographic poles are plotted as points (Lambert Conic, Hammer, Mollweide, Sinusoidal, and van der Grinten). Specify either none (in which case there is no special handling) or pc_lat/pc_dlon. In that case, normal gridlines are only drawn between the latitudes -pc_lat/+pc_lat, and above those latitudes the gridlines are spaced at the (presumably coarser) pc_dlon interval; the two domains are separated by a small circle drawn at the pc_lat latitude [85/90].

PS_COLOR

Determines whether PostScript output should use RGB, HSV, or CMYK when specifying color [RGB]. Note if HSV is selected it does not apply to images which in that case uses RGB.

PS_IMAGE_COMPRESS

Determines if PostScript images are compressed using the Run-Length Encoding scheme (rle), LZW compression (lzw), or not at all (none) [none].

PS_IMAGE_FORMAT

Determines whether images created in PostScript should use ASCII or binary format. The latter takes up less space and executes faster but may choke some printers, especially those off serial ports. Select ascii or bin [ascii].

PS_LINE_CAP

Determines how the ends of a line segment will be drawn. Choose among a butt cap (default) where there is no projection beyond the end of the path, a round cap where a semicircular arc with diameter equal to the linewidth is drawn around the end points, and square cap where a half square of size equal to the linewidth extends beyond the end of the path [butt].

PS_LINE_JOIN

Determines what happens at kinks in line segments. Choose among a miter join where the outer edges of the strokes for the two segments are extended until they meet at an angle (as in a picture frame; if the angle is too acute, a bevel join is used instead, with threshold set by PS_MITER_LIMIT), round join where a circular arc is used to fill in the cracks at the kinks, and bevel join which is a miter join that is cut off so kinks are triangular in shape [miter].

PS_MITER_LIMIT

Sets the threshold angle (integer in 0-180 range) used for mitered joins. 0 and 180 are special flag values that imply the PostScript default [11] and always bevels, respectively. Other values sets the acute angle used to decide between mitered and bevelled.

PS_VERBOSE

If TRUE we will issue comments in the PostScript file that explain the logic of operations. These are useful if you need to edit the file and make changes; otherwise you can set it to FALSE which yields a somewhat slimmer PostScript file [FALSE].

TICK_LENGTH

The length of a tickmark. Normally, tickmarks are drawn on the outside of the map boundaries. To select interior tickmarks, use a negative tick_length [0.2c (or 0.075i)].

TICK_PEN

The pen thickness to be used for tickmarks in dpi units or points (append p) [0.5p].

TIME_FORMAT_PRIMARY

Controls how primary month-, week-, and weekday-names are formatted. Choose among full, abbreviated, and character. If the leading f, a, or c are replaced with F, A, and C the entire annotation will be in upper case.

TIME_FORMAT_SECONDARY

Controls how secondary month-, week-, and weekday-names are formatted. Choose among full, abbreviated, and character. If the leading f, a, or c are replaced with F, A, and C the entire annotation will be in upper case.

TIME_EPOCH

Specifying this parameter also sets TIME_SYSTEM to OTHER. It is a string of the form yyyy-mm-ddT[hh:mm:ss] (Gregorian) or yyyy-Www-ddT[hh:mm:ss] (ISO) indicating the value of the calendar and clock at the origin (zero point) of relative time units (see TIME_UNIT).

TIME_IS_INTERVAL

Used when input calendar data should be truncated and adjusted to the middle of the relevant interval. In the following discussion, the unit u can be one of these time units: (y year, o month, u ISO week, d day, h hour, m minute, and c second). TIME_IS_INTERVAL can have any of the following three values: (1) OFF [Default]. No adjustment, time is decoded as given. (2) +nu. Activate interval adjustment for input by truncate to previous whole number of n units and then center time on the following interval. (3) -nu. Same, but center time on the previous interval. For example, with TIME_IS_INTERVAL = +1o, an input data string like 1999-12 will be interpreted to mean 1999-12-15T12:00:00.0 (exactly middle of December), while if TIME_IS_INTERVAL = OFF then that date is interpreted to mean 1999-12-1T00:00:00.0 (start of December).

TIME_INTERVAL_FRACTION

Determines if partial intervals at the start and end of an axis should be annotated. If the range of the partial interval exceeds the specified fraction of the normal interval stride we will place the annotation centered on the partial interval [0.5].

TIME_LANGUAGE

Language to use when plotting calendar items such as months and days. Select from:

BR

Brazilian Portuguese

CN1

Simplified Chinese

CN2

Traditional Chinese

DE

German

DK

Danish

EH

Basque

ES

Spanish

FI

Finnish

FR

French

GR

Greek

HU

Hungarian

IE

Irish

IL

Hebrew

IS

Icelandic

IT

Italian

JP

Japanese

NL

Dutch

NO

Norwegian

PL

Polish

PT

Portuguese

RU

Russian

SE

Swedish

SG

Scottish Gaelic

TO

Tongan

TR

Turkish

UK

British English

US

US English

If your language is not supported, please examine the $GMTHOME/share/time/us.d file and make a similar file. Please submit it to the GMT Developers for official inclusion.

TIME_SYSTEM

Determines which time epoch the relative time refers to and what the units are. Choose from one of the preset systems below (epoch and units are indicated):

JD

Julian Date, -4713-11-25T12:00:00 d

MJD

Modified Julian Date, 1858-11-27T00:00:00 d

J2000

2000-01-01T00:00:00 d

S1985

1985-01-01T00:00:00 c

UNIX

1970-01-01T00:00:00 c

RD0001

0001-01-01T00:00:00 c

RATA

0000-12-31T00:00:00 d

or specify OTHER and supply your own TIME_EPOCH and TIME_UNIT settings [J2000].

TIME_UNIT

This parameter is active only when TIME_SYSTEM is set to OTHER, and specifies the units of relative time data. Choose y (year - assumes all years are 365.2425 days), o (month - assumes all months are of equal length y/12), d (day), h (hour), m (minute), or c (second).

TIME_WEEK_START

When weeks are indicated on time axes, this parameter determines the first day of the week for Gregorian calendars. (The ISO weekly calendar always begins weeks with Monday.) [Monday (or Sunday)].

UNIX_TIME

(* −U) Specifies if a UNIX system time stamp should be plotted at the lower left corner of the plot [FALSE].

UNIX_TIME_POS

(* −U) Sets the position of the UNIX time stamp relative to the current plots lower left corner [-2c/-2c (or -0.75i/-0.75i)].

VECTOR_SHAPE

Determines the shape of the head of a vector. Normally (i.e., for vector_shape = 0), the head will be triangular, but can be changed to an arrow (1) or an open V (2). Intermediate settings give something in between. Negative values (up to -2) are allowed as well [0].

VERBOSE

(* −V) Determines if GMT programs should display run-time information or run silently [FALSE].

X_AXIS_LENGTH

Sets the default length (> 0) of the x-axis [25c (or 9i)].

Y_AXIS_LENGTH

Sets the default length (> 0) of the y-axis [15c (or 6i)].

X_ORIGIN

(* −X) Sets the x-coordinate of the origin on the paper for a new plot [2.5c (or 1i)]. For an overlay, the default offset is 0.

Y_ORIGIN

(* −Y) Sets the y-coordinate of the origin on the paper for a new plot [2.5c (or 1i)]. For an overlay, the default offset is 0.

Y2K_OFFSET_YEAR

When 2-digit years are used to represent 4-digit years (see various DATE_FORMATs), Y2K_OFFSET_YEAR gives the first year in a 100-year sequence. For example, if Y2K_OFFSET_YEAR is 1729, then numbers 29 through 99 correspond to 1729 through 1799, while numbers 00 through 28 correspond to 1800 through 1828. [1950].

XY_TOGGLE

(* −:) Set if the first two columns of input and output files contain (latitude,longitude) or (y,x) rather than the expected (longitude,latitude) or (x,y). FALSE means we have (x,y) both on input and output. TRUE means both input and output should be (y,x). IN means only input has (y,x), while OUT means only output should be (y,x). [FALSE].

Y_AXIS_TYPE

Determines if the annotations for a y-axis (for linear projections) should be plotted horizontally (hor_text) or vertically (ver_text) [hor_text].

To get a copy of the GMT parameter defaults in your home directory, run

gmtdefaults −D > ~/.gmtdefaults4

You may now change the settings by editing this file using a text editor of your choice, or use gmtset to change specified parameters on the command line.

If you have typographical errors in your .gmtdefaults4 file(s), a warning message will be issued, and the GMT defaults for the affected parameters will be used.

GMT(l), gmtset(l)