grdvector - Plot vector fields from grdfiles

grdvectorcompx.grdcompy.grd-Jparameters[-A] [-Btickinfo] [-Ccptfile] [-E] [-Gfill] [-Ix_inc[m|c][/y_inc[m|c]] ] [-K] [-N] [-O] [-P] [-Qparameters] [-Rwest/east/south/north[r] ] [-S[l]scale] [-T] [-U[/dx/dy/][label] ] [-V] [-Wcontourpen] [-Xx-shift] [-Yy-shift] [-Z] [-ccopies]

grdvectorreads two 2-D gridded files which represents the x- and y- components of a vector field and produces a vector field plot by draw- ing vectors with orientation and length according to the information in the files. Alternatively, polar coordinate components may be used (r, theta).grdvectoris basically a short-hand for using 2 calls togrd2xyzand pasting the output throughpsxy-SV.compx.grdContains the x-component of the vector field.compy.grdContains the y-component of the vector field.-JSelects the map projection. Scale is UNIT/degree, 1:xxxxx, or width in UNIT (upper case modifier). UNIT is cm, inch, or m, depending on the MEASURE_UNIT setting in .gmtdefaults4, but this can be overridden on the command line by appendingc,i, ormto the scale/width value. For map height, max dimension, or min dimension, appendh,+, or-to the width, respectively.CYLINDRICALPROJECTIONS:-Jclon0/lat0/scale(Cassini)-Jjlon0/scale(Miller)-Jmscale(Mercator - Greenwich and Equator as origin)-Jmlon0/lat0/scale(Mercator - Give meridian and standard paral- lel)-Joalon0/lat0/azimuth/scale(Oblique Mercator - point and azimuth)-Joblon0/lat0/lon1/lat1/scale(Oblique Mercator - two points)-Joclon0/lat0/lonp/latp/scale(Oblique Mercator - point and pole)-Jqlon0/scale(Equidistant Cylindrical Projection (Plate Car- ree))-Jtlon0/scale(TM - Transverse Mercator, with Equator as y = 0)-Jtlon0/lat0/scale(TM - Transverse Mercator, set origin)-Juzone/scale(UTM - Universal Transverse Mercator)-Jylon0/lats/scale(Basic Cylindrical Projection)AZIMUTHALPROJECTIONS:-Jalon0/lat0/scale(Lambert).-Jelon0/lat0/scale(Equidistant).-Jflon0/lat0/horizon/scale(Gnomonic).-Jglon0/lat0/scale(Orthographic).-Jslon0/lat0/[slat/]scale(General Stereographic)CONICPROJECTIONS:-Jblon0/lat0/lat1/lat2/scale(Albers)-Jdlon0/lat0/lat1/lat2/scale(Equidistant)-Jllon0/lat0/lat1/lat2/scale(Lambert)MISCELLANEOUSPROJECTIONS:-Jhlon0/scale(Hammer)-Jilon0/scale(Sinusoidal)-Jk[f|s]lon0/scale(Eckert IV (f) and VI (s))-Jnlon0/scale(Robinson)-Jrlon0/scale(Winkel Tripel)-Jvlon0/scale(Van der Grinten)-Jwlon0/scale(Mollweide)NON-GEOGRAPHICALPROJECTIONS:-Jp[a]scale[/origin] (polar (theta,r) coordinates, optionalafor azimuths and offset theta [0])-Jxx-scale[l|ppow][/y-scale[l|ppow]][d] (Linear, log, and power scaling) More details can be found in thepsbasemapman pages.

No space between the option flag and the associated arguments.-AMeans grdfiles have polar (r, theta) components instead of Cartesian (x, y).-BSets map boundary annotation and tickmark intervals; see thepsbasemapman page for all the details.-CUsecptfileto assign colors based on vector length.-ECenter vectors on grid nodes [Default draws from grid node].-GSets color or shade for vector interiors [Default is no fill]. Specify the shade (0-255) or color (r/g/b, each in 0-255, h/s/v, with h in 0-360, s, and v in 0-1, and setCOLOR_MODEL= hsv, or c/m/y/k, each in 0-100 %). Alternatively, specify-Gpdpi/pat-tern, wherepatterngives the number of the built-in pattern (1-90)orthe name of a Sun 1-, 8-, or 24-bit raster file. Thedpisets the resolution of the image. For 1-bit rasters: use-GPfor inverse video, or append:Fr/g/b[B[r/g/b]] to specify fore- and background colors (user/g/b= - for transparency). SeeGMTCookbook & Technical Reference Appendix E for information on individual patterns.-IOnly plot vectors at nodes everyx_inc,y_incapart (must be multiples of original grid spacing). Appendmfor minutes orcfor seconds. [Default plots every node].-KMorePostScriptcode will be appended later [Default terminates the plot system].-NDo NOT clip vectors at map boundaries [Default will clip].-OSelects Overlay plot mode [Default initializes a new plot sys- tem].-PSelects Portrait plotting mode [GMTDefault is Landscape, seegmtdefaultsto change this].-QSelect vector plot [Default is stick-plot]. Optionally, specifyparameterswhich arearrowwidth/headlength/headwidth[Default is 0.075c/0.3c/0.25c(or 0.03i/0.12i/0.1i)]. Append nsizewhich will cause vectors shorter thansizeto have their appearance scaled by length/size.-Rxmin,xmax,ymin,andymaxspecify the Region of interest. For geographic regions, these limits correspond towest,east,south,andnorthand you may specify them in decimal degrees or in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Appendrif lower left and upper right map coordinates are given instead of wesn. The two shorthands-Rg-Rdstand for global domain (0/360 or -180/+180 in longitude respectively, with -90/+90 in latitude). For calendar time coordinates you may either give relative time (relative to the selected TIME_EPOCH and in the selected TIME_UNIT; appendtto-JX|x), or absolute time of the form [date]T[clock] (appendTto-JX|x). At least one ofdateandclockmust be present; theTis always required. Thedatestring must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]] (ISO week calendar), while theclockstring must be of the form hh:mm:ss[.xxx]. The use of delimiters and their type and positions must be as indicated (however, input/output and plotting formats are flexible). Specify a subset of the grid.-SSets scale for vector length in data units per distance measure- ment unit [1]. Appendc,i,m,pto indicate the measurement unit (cm, inch, m, point). Prependlto indicate a fixed length for all vectors.-TMeans azimuth should be converted to angles based on the selected map projection.-UDraw Unix System time stamp on plot. User may specify where the lower left corner of the stamp should fall on the page relative to lower left corner of plot. Optionally, append a label, orc(which will plot the command string.). TheGMTparameters UNIX_TIME and UNIX_TIME_POS can affect the appearance; see thegmtdefaultsman page for details.-VSelects verbose mode, which will send progress reports to stderr [Default runs "silently"].-WSet pen attributes used for vector outlines [Default: width = 1, color = 0/0/0, texture = solid].-X-YShift origin of plot by (x-shift,y-shift). Prependafor abso- lute coordinates; the default (r) will reset plot origin. Givecto center plot using current page size.-ZMeans the angles provided are azimuths rather than direction (requires-A).-cSpecifies the number of plot copies. [Default is 1].

To draw the vector field given by the files r.grd and theta.grd on a linear plot with scale 5 cm per data unit, using vector rather than stick plot, and scale vector magnitudes so that 10 units equal 1 inch, rungrdvectorr.grd theta.grd-Jx5c-A-Q-S10i> gradient.ps

gmt(l),grdcontour(l),psxy(l) GMT4.0 1 Oct 2004 GRDVECTOR(l)

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