See originals: http://www.ntp.org/ntpfaq/NTP-s-time.htm http://weather.msfc.nasa.gov/utc.html Cooridinated Universal Time, abbreviated as UTC, is an international official time standard . Weather observations around the world (including surface, radar and other observations) are always taken with respect to UTC. Prior to 1972, the world's time standard was called Greenwich Mean Time (GMT, 格林尼治平均/标准时间). It was used to set the clocks on ships before they left for a long journey. GMT is based on the mean solar time (平太阳日) which varies a lot by itself. Therefore, it is replaced by UTC, based on a quantum resonance (量子共振) of a cesium (铯) atom, being quite more accurate. Zero (0) hours UTC is midnight in Greenwich England, which lies on the prime meridian (0° longitude). To convert UTC to local time, one would have to add or subtract the local time zone. China: UTC+8; Germany: UTC+2. UTC is based on a 24-hour clock, therefore, afternoon hours such as 4 pm UTC are expressed as 16:00 UTC (sixteen hours, zero minutes). U - Universal means that the time can be used everywhere in the world, meaning that it is independent from time zones (i.e. it is not local time). C - Coordinated means the several institutions contribute their estimate of the current time, and UTC is built by conbining these estimates. Standard_World_Time_Zones.png worldtime.gif
From:https://www.soest.hawaii.edu/gmt/gmt/html/man/gmtdefaults.html GMTDEFAULTS NAME SYNOPSIS DESCRIPTION GMT PARAMETERS EXAMPLES BUGS SEE ALSO NAME gmtdefaults− To list current GMT defaults SYNOPSIS gmtdefaults−D | −L DESCRIPTION gmtdefaults lists the GMT parameter defaults if the option −D is used. There are three ways to change someof the settings: (1) Use the command gmtset , (2) useany texteditor to edit the file .gmtdefaults4 in your home,~/.gmt or current directory (if you do not have this file,run gmtdefaults -D ~/.gmtdefaults4 to get onewith the system default settings), or (3) override anyparameter by specifying one or more −−PARAMETER = value statements onthe commandline of any GMT command ( PARAMETER and VALUE are any combination listed below). Thefirst two options are permanent changes until explicitlychanged back, while the last option is ephemeral and onlyapplies to the single GMT command that received theoverride. GMT can provide default values in US or SIunits. This choice is determined by the contents of thegmt_setup.conf file in GMT ’s sharedirectory. −D Print the system GMT defaults to standard output. Append u forUS defaults or s for SI defaults. . −L Print theuser’s currently active defaults to standardoutput. Your currentlyactive defaults come from the .gmtdefaults4 file in thecurrent working directory, if present; else from the.gmtdefaults4 file in your home directory, if present; elsefrom the file ~/.gmt/.gmtdefaults4, if present; else fromthe system defaults set at the time GMT wascompiled. GMT PARAMETERS The followingis a list of the parameters that are user-definable in GMT . The parameter names are always given in UPPERCASE. The parameter values are case-insensitive unlessotherwise noted. The system defaults are given in brackets . Those marked * can be set on thecommand line as well (the corresponding option is given inparentheses). Note that default distances and lengths beloware given in both cm or inch; the chosen default depends onyour choice of default unit (see MEASURE_UNIT ). Youcan explicitly specify the unit used for distances andlengths by appending c (cm), i (inch), m (meter), or p (points). When no unit isindicated 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 pixelsper inch. Several parameters take only TRUE or FALSE. ANNOT_FONT_PRIMARY Font used for upperannotations, etc. . Specify either the fontnumber or the font name (case sensitive!). The 35 availablefonts 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) for mapannotations . ANNOT_FONT_SECONDARY Font to use for time axissecondary annotations. See ANNOT_FONT_PRIMARY foravailable fonts . ANNOT_FONT_SIZE_SECONDARY Font size ( 0) for timeaxis secondary annotations . ANNOT_MIN_ANGLE If the angle between the mapboundary and the annotation baseline is less than thisminimum value (in degrees), the annotation is not plotted(this may occur for certain oblique projections.) Give avalue in the range 0−90. ANNOT_MIN_SPACING If an annotation would beplotted less than this minimum distance from its closestneighbor, the annotation is not plotted (this may occur forcertain oblique projections.) ANNOT_OFFSET_PRIMARY Distance from end of tickmarkto start of annotation . Anegative offset will place the annotation inside the mapborder. ANNOT_OFFSET_SECONDARY Distance from base of primaryannotation to the top of the secondary annotation (Only applies to time axeswith both primary and secondary annotations). BASEMAP_AXES Sets which axes to draw andannotate. Case sensitive: Upper case means both draw andannotate, lower case means draw axis only. . BASEMAP_FRAME_RGB Color used to draw mapboundaries 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. (black). BASEMAP_TYPE Choose between inside, graph,plain and fancy (thick boundary, alternating black/whiteframe; append + for rounded corners) . For some mapprojections (e.g., Oblique Mercator), plain is the onlyoption even if fancy is set as default. In general, fancyonly applies to situations where the projected x and ydirections parallel the lon and lat directions (e.g.,rectangular projections, polar projections). For situationswhere all boundary ticks and annotations must be inside themaps (e.g., for preparing geotiffs), chose inside. Finally,graph is used for linear projections only and will extendthe axis by 7.5% and add arrow heads. CHAR_ENCODING Names the eight bit characterset being used for text in files and in command lineparameters. This allows GMT to ensure that the PostScript output generates the correct characters onthe plot.. Choose from Standard, Standard+, ISOLatin1,ISOLatin1+, and ISO-8859-x (where x is in the ranges 1-10 or13-15). See Appendix F for details . COLOR_BACKGROUND Color used for the backgroundof images (i.e., when z lowest colortable entry). Givea red/green/blue triplet, with each element in the0−255 range. (black) COLOR_FOREGROUND Color used for the foregroundof images (i.e., when z highest colortable entry). Givea red/green/blue triplet, with each element in the0−255 range. (white) COLOR_IMAGE Selects which operator to usewhen rendering bit-mapped color images. Due to the lack ofthe colorimage operator in some PostScript implementations, as well as some PostScript editorsinability to handle color gradations, GMT offers twodifferent options: adobe (Adobe’s colorimage definition) . tiles (Plot image as many individualrectangles). COLOR_MODEL Selects if color palette filescontain RGB values (r,g,b in 0-255 range), HSV values (h in0-360, s,v in 0-1 range), or CMYK values (c,m,y,k in 0-1range). A COLOR_MODEL setting in the color palettefile will override this setting. Internally, colorinterpolation takes place directly on the RGB values whichcan give unexpected hues, whereas interpolation directly onthe HSV values better preserves the hues. Prepend the prefix+ to force interpolation in the selected colorsystem (does not apply to the CMYK system). For thisadditional option, the defaults take precedence over thecolor palette file . COLOR_NAN Color used for the non-definedareas of images (i.e., where z == NaN). Give ared/green/blue triplet, with each element in the 0−255range. (gray) D_FORMAT Output format (C languageprintf syntax) to be used when printing double precisionfloating point numbers. For geographic coordinates, see OUTPUT_DEGREE_FORMAT . . DEGREE_SYMBOL Determines what symbol is usedto plot the degree symbol on geographic map annotations.Choose between ring, degree, colon, or none . DOTS_PR_INCH Resolution of the plottingdevice (dpi). Note that in order to be as compact aspossible, GMT PostScript output uses integerformats only so the resolution should be set depending onwhat output device you are using. E.g, using 300 and sendingthe output to a Linotype 300 phototypesetter (2470 dpi) willnot take advantage of the extra resolution (i.e.,positioning on the page and line thicknesses are still onlydone in steps of 1/300 inch; of course, text will looksmoother) . ELLIPSOID The (case sensitive) name ofthe ellipsoid used for the map projections . Chooseamong: WGS-84 : WorldGeodetic System (1984) OSU91A : Ohio State University (1991) OSU86F : Ohio State University (1986) Engelis : Goddard Earth Models (1985) SGS-85 : Soviet Geodetic System (1985) TOPEX : Used commonly for altimetry (1990) MERIT-83 : United States Naval Observatory (1983) GRS-80 : International Geodetic Reference System (1980) Hughes-1980 : Hughes Aircraft Company for DMSP SSM/I gridproducts (1980) Lerch : For geoid modelling (1979) ATS77 : Average Terrestrial System, Canada Maritimeprovinces (1977) IAG-75 : International Association of Geodesy (1975) Indonesian : Applies to Indonesia (1974) WGS-72 : World Geodetic System (1972) NWL-10D : Naval Weapons Lab (Same as WGS-72) (1972) South-American : Applies to South America (1969) Fischer-1968 : Used by NASA for Mercury program (1968) Modified-Mercury-1968 : Same as Fischer-1968 (1968) GRS-67 : International Geodetic Reference System (1967) International-1967 : Worldwide use (1967) WGS-66 : World Geodetic System (1966) NWL-9D : Naval Weapons Lab (Same as WGS-66) (1966) Australian : Applies to Australia (1965) APL4.9 : Appl. Physics (1965) Kaula : From satellite tracking (1961) Hough : Applies to the Marshall Islands (1960) WGS-60 : World Geodetic System (1960) Fischer-1960 : Used by NASA for Mercury program (1960) Mercury-1960 : Same as Fischer-1960 (1960) Modified-Fischer-1960 : Applies to Singapore (1960) Fischer-1960-SouthAsia : Same as Modified-Fischer-1960(1960) Krassovsky : Used in the (now former) Soviet Union (1940) War-Office : Developed by G. T. McCaw (1926) International-1924 : Worldwide use (1924) Hayford-1909 : Same as the International 1924 (1909) Helmert-1906 : Applies to Egypt (1906) Clarke-1880 : Applies to most of Africa, France (1880) Clarke-1880-Arc1950 : Modified Clarke-1880 for Arc 1950(1880) Clarke-1880-IGN : Modified Clarke-1880 for IGN (1880) Clarke-1880-Jamaica : Modified Clarke-1880 for Jamaica(1880) Clarke-1880-Merchich : Modified Clarke-1880 for Merchich(1880) Clarke-1880-Palestine : Modified Clarke-1880 for Palestine(1880) Andrae : Applies to Denmark and Iceland (1876) Clarke-1866 : Applies to North America, the Philippines(1866) Clarke-1866-Michigan : Modified Clarke-1866 for Michigan(1866) Struve : Friedrich Georg Wilhelm Struve (1860) Clarke-1858 : Clarke’s early ellipsoid (1858) Airy : Applies to Great Britain (1830) Airy-Ireland : Applies to Ireland in 1965 (1830) Modified-Airy : Same as Airy-Ireland (1830) Bessel : Applies to Central Europe, Chile, Indonesia (1841) Bessel-Schwazeck : Applies to Namibia (1841) Bessel-Namibia : Same as Bessel-Schwazeck (1841) Bessel-NGO1948 : Modified Bessel for NGO 1948 (1841) Everest-1830 : India, Burma, Pakistan, Afghanistan, Thailand(1830) Everest-1830-Kalianpur : Modified Everest for Kalianpur(1956) (1830) Everest-1830-Kertau : Modified Everest for Kertau, Malaysia Singapore (1830) Everest-1830-Timbalai : Modified Everest for Timbalai, SabahSarawak (1830) Everest-1830-Pakistan : Modified Everest for Pakistan (1830) Walbeck : First least squares solution by Finnish astronomer(1819) Plessis : Old ellipsoid used in France (1817) Delambre : Applies to Belgium (1810) CPM : Comm. des Poids et Mesures, France (1799) Maupertius : Really old ellipsoid used in France (1738) Sphere : The mean radius in WGS-84 (for spherical/platetectonics applications) (1984) Moon : Moon (IAU2000) (2000) Mercury : Mercury (IAU2000) (2000) Venus : Venus (IAU2000) (2000) Mars : Mars (IAU2000) (2000) Jupiter : Jupiter (IAU2000) (2000) Saturn : Saturn (IAU2000) (2000) Uranus : Uranus (IAU2000) (2000) Neptune : Neptune (IAU2000) (2000) Pluto : Pluto (IAU2000) (2000) Note that forsome global projections, GMT may use a sphericalapproximation of the ellipsoid chosen, setting theflattening to zero, and using a mean radius. A warning willbe given when this happens. If a different ellipsoid namethan those mentioned here is given, GMT will attemptto parse the name to extract the semi-major axis ( a in m) and the flattening. Formats allowed are: a implies a zero flattening a , inv_f where inv_f is the inverseflattening a , b= b where b is the semi-minor axis (inm) a , f= f where f is the flattening This way acustom ellipsoid (e.g., those used for other planets) may beused. Further note that coordinate transformations in mapproject can also specify specific datums; see the mapproject man page for further details and how toview ellipsoid and datum parameters. FIELD_DELIMITER This setting determines whatcharacter will separate ASCII output data columns written by GMT . Choose from tab, space, comma, and none . FRAME_PEN Pen attributes used to drawplain map frame in dpi units or points (append p) . FRAME_WIDTH Width ( 0) of map bordersfor fancy map frame . GLOBAL_X_SCALE Global x-scale ( 0) toapply to plot-coordinates before plotting. Normally used toshrink the entire output down to fit a specific height/width . GLOBAL_Y_SCALE Same, but for y-coordinates . GRID_CROSS_SIZE_PRIMARY Size (= 0) of grid cross atlon-lat intersections. 0 means draw continuous gridlinesinstead . GRID_CROSS_SIZE_SECONDARY Size (= 0) of grid cross atsecondary lon-lat intersections. 0 means draw continuousgridlines instead . GRID_PEN_PRIMARY Pen attributes used to drawgrid lines in dpi units or points (append p) . GRID_PEN_SECONDARY Pen attributes used to drawgrid lines in dpi units or points (append p) . GRIDFILE_FORMAT Default file format for grids,with optional scale, offset and invalid value, written as ff / scale / offset / invalid . The2-letter format indicator can be one of . The first letter indicatesnative GMT binary, old format netCDF,COARDS-compliant netCDF, Surfer format or Sun Raster format.The second letter stands for byte, short, int, float anddouble, respectively. When / invalid is omitted theappropriate value for the given format is used (NaN orlargest negative). When / scale / offset isomitted, /1.0/0.0 is used. . GRIDFILE_SHORTHAND If TRUE, all grid file namesare examined to see if they use the file extension shorthanddiscussed in Section 4.17 of the GMT TechnicalReference and Cookbook. If FALSE, no filename expansion isdone . HEADER_FONT Font to use when plottingheaders. See ANNOT_FONT_PRIMARY for available fonts . HEADER_FONT_SIZE Font size ( 0) for header . HEADER_OFFSET Distance from top of axisannotations (or axis label, if present) to base of plotheader . HISTORY If TRUE, passes the history ofpast common command options via the hidden .gmtcommands4file . HSV_MAX_SATURATION Maximum saturation (0−1)assigned for most positive intensity value . HSV_MIN_SATURATION Minimum saturation (0−1)assigned for most negative intensity value . HSV_MAX_VALUE Maximum value (0−1)assigned for most positive intensity value . HSV_MIN_VALUE Minimum value (0−1)assigned for most negative intensity value . INPUT_CLOCK_FORMAT Formatting template thatindicates how an input clock string is formatted. Thistemplate is then used to guide the reading of clock stringsin data fields. To properly decode 12-hour clocks, append amor pm (or upper case) to match your data records. Asexamples, try hh:mm, hh:mm:ssAM, etc. . INPUT_DATE_FORMAT Formatting template thatindicates how an input date string is formatted. Thistemplate is then used to guide the reading of date stringsin data fields. You may specify either Gregorian calendarformat or ISO week calendar format. Gregorian calendar: Useany combination of yyyy (or yy for 2-digit years; if so see Y2K_OFFSET_YEAR ), mm (or o for abbreviated month namein the current time language), and dd, with or withoutdelimiters. For day-of-year data, use jjj instead of mmand/or dd. Examples can be ddmmyyyy, yy-mm-dd, dd-o-yyyy,yyyy/dd/mm, yyyy-jjj, etc. ISO Calendar: Expected templateis yyyy W ww d, where ww is ISO week and d is ISO weekday. Either template must be consistent, e.g., you cannotspecify months if you don’t specify years. Examplesare yyyyWwwd, yyyy-Www, etc. . INTERPOLANT Determines if linear (linear),Akima’s spline (akima), natural cubic spline (cubic)or no interpolation (none) should be used for 1-Dinterpolations in various programs . IO_HEADER ( * −H ) Specifieswhether input/output ASCII files have header record(s) ornot . LABEL_FONT Font to use when plottinglabels below axes. See ANNOT_FONT_PRIMARY foravailable fonts . LABEL_FONT_SIZE Font size ( 0) for labels . LABEL_OFFSET Distance from base of axisannotations to the top of the axis label . LINE_STEP Determines the maximum length( 0) of individual straight line-segments when drawingarcuate lines MAP_SCALE_FACTOR Changes the default map scalefactor used for the Polar Stereographic , UTM , and Transverse Mercator projections in orderto minimize areal distortion. Provide a new scale-factor orleave as default. MAP_SCALE_HEIGHT Sets the height ( 0) on themap of the map scale bars drawn by various programs . MEASURE_UNIT Sets the unit length. Choosebetween cm, inch, m, and point. . Note that, in GMT , one point is defined as 1/72 inch (the PostScript definition), while it is often defined as1/72.27 inch in the typesetting industry. There is nouniversal definition. N_COPIES ( * −c ) Number ofplot copies to make . N_HEADER_RECS Specifies how many headerrecords to expect if −H is turned on . NAN_RECORDS Determines what happens wheninput records containing NaNs for x or y (andin some cases z ) are read. Choose between skip , which will simply report how many bad recordswere skipped, and pass , which will passthese records on to the calling programs. For most programsthis will result in output records with NaNs as well, butsome will interpret these NaN records to indicate gaps in aseries; programs may then use that information to detectsegmentation (if applicable). OBLIQUE_ANNOTATION This integer is a sum of 6 bitflags (most of which only are relevant for obliqueprojections): If bit 1 is set (1), annotations will occurwherever a gridline crosses the map boundaries, elselongitudes will be annotated on the lower and upperboundaries only, and latitudes will be annotated on the leftand right boundaries only. If bit 2 is set (2), thenlongitude annotations will be plotted horizontally. If bit 3is set (4), then latitude annotations will be plottedhorizontally. If bit 4 is set (8), then oblique tickmarksare extended to give a projection equal to the specifiedtick_length. If bit 5 is set (16), tickmarks will be drawnnormal to the border regardless of gridline angle. If bit 6is set (32), then latitude annotations will be plottedparallel to the border. To set a combination of these, addup the values in parentheses. . OUTPUT_CLOCK_FORMAT Formatting template thatindicates how an output clock string is to be formatted.This template is then used to guide the writing of clockstrings in data fields. To use a floating point format forthe smallest unit (e.g., seconds), append .xxx, where thenumber of x indicates the desired precision. If no floatingpoint is indicated then the smallest specified unit will berounded off to nearest integer. For 12-hour clocks, appendam, AM, a.m., or A.M. ( GMT will replace a|A with p|Pfor pm). If your template starts with a leading hyphen (-)then each integer item (y,m,d) will be printed withoutleading zeros (default uses fixed width formats). Asexamples, try hh:mm, hh.mm.ss, hh:mm:ss.xxxx, hha.m., etc. . OUTPUT_DATE_FORMAT Formatting template thatindicates how an output date string is to be formatted. Thistemplate is then used to guide the writing of date stringsin data fields. You may specify either Gregorian calendarformat or ISO week calendar format. Gregorian calendar: Useany combination of yyyy (or yy for 2-digit years; if so see Y2K_OFFSET_YEAR ), mm (or o for abbreviated month namein the current time language), and dd, with or withoutdelimiters. For day-of-year data, use jjj instead of mmand/or dd. As examples, try yy/mm/dd, yyyy=jjj, dd-o-yyyy,dd-mm-yy, yy-mm, etc. ISO Calendar: Expected template isyyyy W ww d, where ww is ISO week and d is ISO weekday. Either template must be consistant, e.g., you cannotspecify months if you don’t specify years. Asexamples, try yyyyWww, yy-W-ww-d, etc. If your templatestarts with a leading hyphen (-) then each integer item(y,m,d) will be printed without leading zeros (default usesfixed width formats) . OUTPUT_DEGREE_FORMAT Formatting template thatindicates how an output geographical coordinate is to beformatted. This template is then used to guide the writingof geographical coordinates in data fields. The template isin general of the form D or ddd ] . By default, longitudes will bereported in the -180/+180 range. The various terms have thefollowing purpose: + Output longitude in the 0 to 360 range - Output longitude in the -360 to 0 range D Use D_FORMAT for floating pointdegrees. 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 imagingbackground, i.e., the paper. Give a red/green/blue triplet,with each element in the 0−255 range. (white). PAPER_MEDIA Sets the physical format of thecurrent plot paper . The following formats(and their widths and heights in points) are recognized(Additional site-specific formats may be specified in thegmt_custom_media.conf file in $GMT_SHAREDIR /conf or~/.gmt; 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 statement 396 612 note 540 720 letter 612 792 legal 612 1008 11x17 792 1224 tabloid 792 1224 ledger 1224 792 For acompletely custom format (e.g., for large format plotters)you may also specify Custom_WxH, where W and H are in pointsunless you append a unit to each dimension ( c , i , m or p ). To force theprinter to request a manual paper feed, append’-’ to the media name, e.g., A3- will requirethe user to insert a A3 paper into the printer’smanual 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 . PAGE_ORIENTATION ( * −P ) Sets theorientation of the page. Choose portrait or landscape . PLOT_CLOCK_FORMAT Formatting template thatindicates how an output clock string is to be plotted. Thistemplate is then used to guide the formatting of clockstrings in plot annotations. See OUTPUT_CLOCK_FORMAT for details. . PLOT_DATE_FORMAT Formatting template thatindicates how an output date string is to be plotted. Thistemplate is then used to guide the plotting of date stringsin data fields. See OUTPUT_DATE_FORMAT for details.In addition, you may use a single o instead of mm (to plotmonth name) and u instead of W ww to plot Week##. Both of these text strings will be affected by the TIME_LANGUAGE , TIME_FORMAT_PRIMARY and TIME_FORMAT_SECONDARY setting. . PLOT_DEGREE_FORMAT Formatting template thatindicates how an output geographical coordinate is to beplotted. This template is then used to guide the plotting ofgeographical coordinates in data fields. See OUTPUT_DEGREE_FORMAT for details. In addition, youcan append A which plots the absolute value of thecoordinate. The default is ddd:mm:ss. Not all items may beplotted as this depends on the annotation interval. POLAR_CAP Controls the appearance ofgridlines near the poles for all azimuthal projections and afew others in which the geographic poles are plotted aspoints (Lambert Conic, Hammer, Mollweide, Sinusoidal, andvan der Grinten). Specify either none (in which case thereis no special handling) or pc_lat / pc_dlon . Inthat case, normal gridlines are only drawn between thelatitudes - pc_lat /+ pc_lat , and above thoselatitudes the gridlines are spaced at the (presumablycoarser) pc_dlon interval; the two domains areseparated by a small circle drawn at the pc_lat latitude . Note for r-theta (polar) projection wherer = 0 is at the center of the plot the meaning of the cap isreversed, i.e., the default 85/90 will draw a r = 5 radiuscircle at the center of the map with less frequent radiallines there. PS_COLOR Determines whether PostScript output should use RGB, HSV, CMYK, or GRAYwhen specifying color . Note if HSV is selected it doesnot apply to images which in that case uses RGB. Whenselecting GRAY, all colors will be converted to gray scaleusing YIQ (television) conversion. PS_IMAGE_COMPRESS Determines if PostScript images are compressed using the Run-Length Encoding scheme(rle), Lempel-Ziv-Welch compression (lzw), or not at all(none) . PS_IMAGE_FORMAT Determines whether imagescreated in PostScript should use ASCII or binaryformat. The latter takes up less space and executes fasterbut may choke some printers, especially those off serialports. Select ascii or bin . PS_LINE_CAP Determines how the ends of aline segment will be drawn. Choose among a butt cap(default) where there is no projection beyond the end of thepath, a round cap where a semicircular arc withdiameter equal to the linewidth is drawn around the endpoints, and square cap where a half square of sizeequal to the linewidth extends beyond the end of the path . PS_LINE_JOIN Determines what happens atkinks in line segments. Choose among a miter joinwhere the outer edges of the strokes for the two segmentsare extended until they meet at an angle (as in a pictureframe; if the angle is too acute, a bevel join is usedinstead, with threshold set by PS_MITER_LIMIT ), round join where a circular arc is used to fill inthe cracks at the kinks, and bevel join which is amiter join that is cut off so kinks are triangular in shape . PS_MITER_LIMIT Sets the threshold angle indegrees (integer in 0-180 range) used for mitered joinsonly. When the angle between joining line segments issmaller than the threshold the corner will be bevelledinstead of mitered. The default threshold is 35 degrees.Setting the threshold angle to 0 implies the PostScript default of about 11 degrees. Setting thethreshold angle to 180 causes all joins to be beveled. PS_VERBOSE If TRUE we will issue commentsin the PostScript file that explain the logic ofoperations. These are useful if you need to edit the fileand make changes; otherwise you can set it to FALSE whichyields a somewhat slimmer PostScript file . TICK_LENGTH The length of a tickmark.Normally, tickmarks are drawn on the outside of the mapboundaries. To select interior tickmarks, use a negativetick_length . TICK_PEN Pen attributes to be used fortickmarks in dpi units or points (append p) . TIME_EPOCH Specifies the value of thecalendar and clock at the origin (zero point) of relativetime units (see TIME_UNIT ). It is a string of theform yyyy-mm-ddT (Gregorian) oryyyy-Www-ddT (ISO) Default is 2000-01-01T12:00:00,the epoch of the J2000 system. 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 arereplaced with F, A, and C the entire annotation will be inupper 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 arereplaced with F, A, and C the entire annotation will be inupper case. TIME_INTERVAL_FRACTION Determines if partial intervalsat the start and end of an axis should be annotated. If therange of the partial interval exceeds the specified fractionof the normal interval stride we will place the annotationcentered on the partial interval . TIME_IS_INTERVAL Used when input calendar datashould be truncated and adjusted to the middle of therelevant 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 threevalues: (1) OFF . No adjustment, time is decoded asgiven. (2) + n u . Activate interval adjustmentfor input by truncate to previous whole number of n units and then center time on the following interval. (3)- n u . Same, but center time on the previousinterval. For example, with TIME_IS_INTERVAL = +1o,an input data string like 1999-12 will be interpreted tomean 1999-12-15T12:00:00.0 (exactly middle of December),while if TIME_IS_INTERVAL = OFF then that date isinterpreted to mean 1999-12-01T00:00:00.0 (start ofDecember) . TIME_LANGUAGE Language to use when plottingcalendar 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 HI Hawaiian 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 yourlanguage is not supported, please examine the $GMT_SHAREDIR /time/us.d file and make a similar file.Please submit it to the GMT Developers for officialinclusion. Custom language files can be placed indirectories $GMT_SHAREDIR /time or ~/.gmt. TIME_SYSTEM Shorthand for a combination of TIME_EPOCH and TIME_UNIT , specifying whichtime epoch the relative time refers to and what the unitsare. Choose from one of the preset systems below (epoch andunits are indicated): JD -4713-11-25T12:00:00 d (Julian Date) MJD 1858-11-17T00:00:00 d (Modified Julian Date) J2000 2000-01-01T12:00:00 d (Astronomical time) S1985 1985-01-01T00:00:00 c (Altimetric time) UNIX 1970-01-01T00:00:00 c (UNIX time) RD0001 0001-01-01T00:00:00 c RATA 0000-12-31T00:00:00 d This parameter is not stored inthe .gmtdefaults4 file but is translated to the respectivevalues of TIME_EPOCH and TIME_UNIT . TIME_UNIT Specifies the units of relativetime data since epoch (see TIME_EPOCH ). 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 ontime axes, this parameter determines the first day of theweek for Gregorian calendars. (The ISO weekly calendaralways begins weeks with Monday.) . TRANSPARENCY Makes printed materialtransparent. Specify transparency in percent: 0 is opaque(normal overlay plotting), 100 is fully transparent (i.e.,nothing will show). Use either as a pair( stroke / fill ) to set the transparency ofstroked material (lines) or filled material (polygons)separately, or use a single number to set both to the samevalue . Warning: Most printers and PostScript viewers cannot print or will not show transparency. They will simplyignore your attempt to create transparency and will plot anymaterial as opaque. Ghostscript and all itsderivatives like ps2raster , Apple’s Preview and the CUPS printing system are amongthose programs incapable of dealing with transparency. Ifyou want to view transparent material you need to use Acrobat Distiller to create a PDF file. Note that thesettings of Acrobat Distiller need to be changed tomake transparency effective: change /AllowTransparency totrue in the .joboptions file. UNIX_TIME ( * −U ) Specifiesif a UNIX system time stamp should be plotted at the lowerleft corner of the plot . UNIX_TIME_POS ( * −U ) Sets thejustification and the position of the UNIX time stamp boxrelative to the current plots lower left corner of the plot . UNIX_TIME_FORMAT Defines the format of the timeinformation in the UNIX time stamp. This format is parsed bythe C function strftime , so that virtually any textcan be used (even not containing any time information) . VECTOR_SHAPE Determines the shape of thehead of a vector. Normally (i.e., for vector_shape = 0), thehead will be triangular, but can be changed to an arrow (1)or an open V (2). Intermediate settings give something inbetween. Negative values (up to -2) are allowed as well . VERBOSE ( * −V ) Determinesif GMT programs should display run-time informationor run silently . X_AXIS_LENGTH Sets the default length (0) of the x-axis . X_ORIGIN ( * −X ) Sets thex-coordinate of the origin on the paper for a new plot . For an overlay, the defaultoffset is 0. XY_TOGGLE ( * −: ) Set if thefirst 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 outputshould be (y,x). IN means only input has (y,x), while OUTmeans only output should be (y,x). . Y_AXIS_LENGTH Sets the default length (0) of the y-axis . Y_ORIGIN ( * −Y ) Sets they-coordinate of the origin on the paper for a new plot . For an overlay, the defaultoffset is 0. Y_AXIS_TYPE Determines if the annotationsfor a y-axis (for linear projections) should be plottedhorizontally (hor_text) or vertically (ver_text) . Y2K_OFFSET_YEAR When 2-digit years are used torepresent 4-digit years (see various DATE_FORMAT s), Y2K_OFFSET_YEAR gives the first year in a 100-yearsequence. 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. . SPECIFYINGPENS pen The attributes of lines and symbol outlinesas defined by pen is a comma delimetered list of width , color and texture , each of whichis optional. width can be indicated as a measure(points, centimeters, inches) or as faint , thin , thick , fat , or obese . color specifies a gray shade or color (see SPECIFYINGCOLOR below). texture is a combination of dashes‘-’ and dots ‘.’. SPECIFYINGFILL fill The attribute fill specifies thesolid shade or solid color (see SPECIFYING COLORbelow) or the pattern used for filling polygons. Patternsare specified as p dpi/pattern , where pattern gives the number of the built-in pattern(1-90) or the name of a Sun 1-, 8-, or 24-bit rasterfile. The dpi sets the resolution of the image. For1-bit rasters: use P dpi/pattern for inversevideo, or append :F color ] to specifyfore- and background colors (use color = - fortransparency). See GMT Cookbook TechnicalReference Appendix E for information on individualpatterns. SPECIFYINGCOLOR color The color of lines, areas andpatterns can be specified by a valid color name; by a grayshade (in the range 0−255); by a decimal color code(r/g/b, each in range 0−255; h-s-v, ranges0−360, 0−1, 0−1; or c/m/y/k, each in range0−1); or by a hexadecimal color code (#rrggbb, as usedin HTML). See the gmtcolors manpage for moreinformation and a full list of color names. EXAMPLES To get a copyof the GMT parameter defaults in your home directory,run gmtdefaults−D ~/.gmtdefaults4 You may nowchange the settings by editing this file using a text editorof your choice, or use gmtset to change specifiedparameters on the command line. BUGS If you havetypographical errors in your .gmtdefaults4 file(s), awarning message will be issued, and the GMT defaultsfor the affected parameters will be used. SEE ALSO GMT (1), gmtcolors (5), gmtget (1), gmtset (1)
GMT − The Generic Mapping Tools data processing and display software package GMT is a collection of public-domain Unix tools that allows you to manipulate x,y and x,y,z data sets (filtering, trend fitting, gridding, projecting, etc.) and produce PostScript illustrations ranging from simple x-y plots, via contour maps, to artificially illuminated surfaces and 3-D perspective views in black/white or full color. Linear, log10, and power scaling is supported in addition to 25 common map projections. The processing and display routines within GMT are completely general and will handle any (x,y) or (x,y,z) data as input.Significantly improved versions (3.1-3.3, 3.3.1-6), 3.4, 3.4.1-5, and 4.0-4.5.3 were released between November 1998 and July 2010, culminating in the Mar 2011 introduction of 4.5.6. GMT now is used by 15,000 users worldwide in a broad range of disciplines. The homepage of GMT is http://www.soest.hawaii.edu/gmt/ The installation for windowsis as follows: Reprint from the website 1.准备文件如下 (文件下载网址:http://gmt.soest.hawaii.edu/) netcdf-4.1.1 GMT_basic_install.exe GMT_pdf_install.exe GSHHS_highfull_install.exe 2.执行安装以下文件 （以安装到D盘为例） GMT_basic_install.exe GMT_pdf_install.exe GSHHS_highfull_install.exe 此时会在D:\GMT目录下产生有以下文件夹：bin include lib share 3.把netcdf-4.1.1文件拷到D:\GMT目录下 （解压netcdf 后的文件） 4.把D:\GMT\share下所有 *.d; *.cdf; *.ps 文件及conf文件夹下的所有文件拷到D:\GMT目录下 5.在D:\GMT目录下创建gmt.bat文件 目的：设置GMTHOME，HOME 和 NETCDF,修改PATH，LIB，INCLUDE下面是gmt.bat文件的内容,拷贝下来再,保存为gmt.bat, 然后根据自己的情况加以修改，这里以上面创建的目录为例。 gmt.bat文件的内容如下： ECHO OFF REM ---------------------------------------------------- REM REM @(#)gmtenv.bat 1.10 03/08/00 REM REM Copyright (c) 1991-2000 by P. Wessel and W. H. F. Smith REM See COPYING file for copying and redistribution conditions. REM REM This program is free software; you can redistribute it and/or modify REM it under the terms of the GNU General Public License as published by REM the Free Software Foundation; version 2 of the License. REM REM This program is distributed in the hope that it will be useful, REM but WITHOUT ANY WARRANTY; without even the implied warranty of REM MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the REM GNU General Public License for more details. REM REM Contact info: www.soest.hawaii.edu/gmt REM -------------------------------------------------------------------- REM REM Sets the GMT environment needed under WinXP. REM REM Author: Paul Wessel, 07-MAR-2000 REM REM ---------------------------------------------------- REM Set NETCDF, GMTHOME, and HOME: REM ---------------------------------------------------- SET NETCDF=d:\GMT\netcdf-4.1.1 SET GMTHOME=d:\GMT SET HOME=d:\GMT REM ---------------------------------------------------- REM Must set INCLUDE and LIB if GMT source is to be used REM OR compiled. If not, REM these lines out. REM ---------------------------------------------------- SET INCLUDE=%INCLUDE%;%NETCDF%\INCLUDE SET LIB=%LIB%;%NETCDF%\LIB;%GMTHOME%\LIB REM ---------------------------------------------------- REM STOP HERE, Now appending to PATH: REM ---------------------------------------------------- SET PATH=%PATH%;%GMTHOME%\BIN;%NETCDF%\LIB REM ---------------------------------------------------- ECHO GMT 4.5.2 Environment initialized doskey 6.进入DOS，在DOS下进入D:\GMT执行gmt.bat，显示如下： D:\GMTgmt.bat D:\GMTECHO OFF GMT 4.5.2 Environment initialized 此时可输入一个命令psxy等进行测试，如果出现此命令的说明，则表示成功了。 7.此外gawk也是window下常用程序,可以在下面网站下载 http://gnuwin32.sourceforge.net/packages/gawk.htm 下载后,安装在D:\GMT 目录下(可以安装在任何目录下)，只要把D:\GMT\GnuWin32\bin下面的所有文件拷贝到 D:\GMT\bin 下就可以了。 8.PS查看器ghostview的安装 在安装Ghostview前先安装Ghostscript，这两个软件都可以网上自由获取 http://pages.cs.wisc.edu/~ghost/ 按先后顺序依次安装，可以安装在任何一个文件夹。安装后把gs\gs8.63\bin 下的gswin32.exe可执行文件和Ghostgum\gsview下的gsview32.exe可执行文件拷贝到D:\GMT\bin 下即可。 近来初学GMT软件，在Win下先尝试安装了该软件，安装过程中借鉴了很多网上分享的资料，对一些作者表示感谢。
Chapter 4 Theory of Rectifiable n-Varifolds 15 Basic Definitions and Properties 16 First Variation 17 Monotonicity Formula And Basic Consequences 18 Pioncare and Sobolev Inequalities 19 Miscellaneous Additional Consequences Of the Mo This is done when I was suffering lecturing Geometric Measure Theory by Leon Simon. Chapter 5 is devoted to Allard regularity theory, but I've no time to input it in a Latex form.
GMT-The Generic Mapping Tools ，即通用制图工具，是一个开源的工具集，主要用于 XY 和 XYZ 数据的处理和显示，包括栅格化、过滤和各种地图投影等操作。 GMT 最初是由哥伦比亚大学的两位毕业生 Paul Wessel 和 Walter H. F. Smith 于 1988 年创建的，至今已经发展到版本 4.5.0 。 经过这段时间的了解，感觉该软件主要有以下几个优点：（ 1 ）完全免费；（ 2 ）源代码是开放的，可以进行二次开发；（ 3 ）可以在多种系统下安装和使用，如 UNIX ， Linux ， MkLinux ， Mac OS 9 ， Windows 和 OS/2 ，但是每个系统下的安装要求是不一样的；（4） GMT 好比一个工具箱，每个工具之间相对独立，操作起来更为灵活，这也是 GMT 研究小组的一个特别考虑；（ 5 ）有很多免费数据资源都可以被 GMT 调用，尤其是 NOAA , USGS , NGDC , NEIC 等；（ 6 ）制作出来的图形图像精美，感觉比 ArcGis 和 MapGis 等软件成图的效果要好。正是由于以上诸多优点，该软件已经被较为广泛应用于医学，工程，物理，数学，地球科学，社会科学等领域。 由于该软件的最初是在 UNIX 系统上发展的，所以对于初学者来说早期的版本安装和使用方面还是有点麻烦的，我也是学习第一次安装该软件，经过摸索，终于在 Windows XP 系统下安装成功。习惯了 Windows 操作的人来说，突然要用 DOS 操作，确实需要一段时间的适应，故可以安装一个 GUI （图形交互界面）软件 Win4GMT 。具体安装过程如下： 1. Install GMT 3 (E g : C : \GMT\ ) . As you will see GMT3 programs will be installed in C : \GMT\ bin and rivers, border, shorelines, patterns etc in C:\GMT\share\coast and gmtenv.bat in C : \GMT\ ( Note: I n GMT 4 .5.0 , gmtenv.bat cant be need any more, and the installer has done the work and set the path. ) 2. S et Home: Modify gmtenv.bat with an ASCII editor in order to set your home dir . SET NETCDF= C : \GMT\ SET GMTHOME= C : \GMT\ SET HOME= C : \ USERS \ USERS \ PROJECTS or C :\ GMT \ TEMP SET PATH=%PATH%; %GMTHOME%\BIN; %NETCDF%\LIB 3. R un cmd command to open this window i n a DOS window . I n GMT 4 .5.0 , .gmtdefaults is created by default in C : \ GMT \bin, you should copy it to C : \GMT\. Then c lose the window . 4. if necessary, install Ghostsview or other postscript viewer or editor . 5. Put netcdf.dll in C : \GMT\. 6. Unzip the Win4GMT and r un setup.exe to install it . To avoid problems , Please install Win4GMT in the GMT Home Directory ( C : \GMT ). 7. Reboot the computer . 8. Configure folders in Preferences menu when starts the program or edit win4gmt.ini in C:\WINDOWS or C:\WINNT folder . Notes: Setup will create a subdirectory ( man ) where will be installed the html version of the GMT manuals. If you have problems with OLEAUT32.DLL (in some cases, problems has been reported) . R ename your oleaut32.dll (just in case) and copy the ftp file in your system directory ( C : \WINDOWS\S ystem) . Then r estart the computer. 其它： GMT下载地址： http://gmt.soest.hawaii.edu/ Win4GMT下载地址： http://www.icm.csic.es/gma
gmt 中的surface---不完整 2008-05-21 23:34 在gmt中由xyz文件转到grid的文件有两个主要命令：xyz2grd, surface,前面已经提到xyz2grd，xyz2grd要求等间隔采样，有时候显得很不方便。而surface可以提供一个较好的方式 Adjustable tension continuous curvature surface gridding 可调整的曲线表面网格？由manual给出的解释是 A continuous curvature gridding algorithm 应该可以理解为曲率连续的网格插值算法，具体的例子在cookbook的6.14，6.16都有用到 主要选项： surface -Goutput_grdfile_name -Ixinc ] -Rwest/east/south/north ] ] ] ] ] ] ] -G 输出文件名 -xinc/yinc: 给出插值后的网格间隔 -R：指定坐标范围 -A： -Z：是插值的收敛标准 -L：？强行指定解的范围？ without any modifiers indicate that x is longitude and periodic in 360: -L constrain the range of output values: -Lllimit specifies lower limit; forces solution to be = limit. -Lulimit specifies upper limit; forces solution to be = limit. limit can be any number, or the letter d for min (or max) input data value, or the filename of a grdfile with bounding values. . Example: -Ll0 gives a non-negative solution. -N sets max n_iterations in each cycle; default = 250. 设置每个圆的最大迭代数 -S 除非网格是病态的 sets search_radius to initialize grid; default = 0 will skip this step. This step is slow and not needed unless grid dimensions are pathological; i.e., have few or no common factors. Append m to give search_radius in minutes. -T adds Tension to the gridding equation; use a value between 0 and 1. default = 0 gives minimum curvature (smoothest; bicubic) solution. 1 gives a harmonic spline solution (local max/min occur only at data points). typically 0.25 or more is good for potential field (smooth) data; 0.75 or so for topography. Experiment. Append B or b to set tension in boundary conditions only; Append I or i to set tension in interior equations only; 关系到插值的结果？详情见cookboo 6.16图 -Z sets over_relaxation parameter. Default = 1.4 Use a value between 1 and 2. Larger number accelerates convergence but can be unstable. Use 1 if you want to be sure to have (slow) stable convergence. 控制收敛速度
标签: GMT
