GMT绘制子图并添加图例

GMT代码：

gmt begin super tif 
   gmt set FONT=15p,4,black
   gmt subplot begin 3x1 -Fs18c/3c  -A  -M0.1c/-0.4c   
   REM 绘制第一个图
   gmt subplot set 0 -A(A) 
   gmt basemap -R1991T/2020T/-1.4/-1.18 -JX? -Byaf+l"DTC (m)"  -BWsrt
   echo N 5.5c 2.5c 2.5c 2.5c 2.5c > tmp.dat
   REM  S dx1   symbol size  fill       pen         dx2  text  图例
   echo S 0.2c c 0.15c red 0.8p,red       -    DTC from ECMWF Interim >> tmp.dat
   echo S -    c 0.3c - 0.8p,blue      -    TOPEX >> tmp.dat
   echo S -    t 0.3c - 0.8p,green     -    Jason-1 >> tmp.dat
   echo S -    s 0.3c - 0.8p,black     -    Jason-2 >> tmp.dat
   echo S -    d 0.3c - 0.8p,lightblue -    Jason-3 >> tmp.dat  
   gmt legend tmp.dat -DjBL+w15.5c+o0.85c/0.1c -F+p0.3p --FONT=10p,4,black
   gmt plot  TP_DTC.txt -fi0t -Sc0.15c  -W0.2p,blue    
   gmt plot new_dtc_from_ecmwf.txt -fi0t -Sc0.05c -Gred -W0.05p,red 
   gmt plot Jason1_DTC.txt -fi0t -St0.2c -W0.2p,green 
   gmt plot Jason2_DTC.txt -fi0t -Ss0.2c -W0.2p,black 
   gmt plot Jason3_DTC.txt -fi0t -Sd0.2c -W0.2p,lightblue 
   REM 绘制第二个图
   gmt subplot set 1 -A(B)
   gmt basemap -R1991T/2020T/-0.11/0 -JX?  -Byaf+l"WTC (m)"  -BWsrt
   gmt plot TP_WTC.txt -fi0t -Sc0.15c -W0.2p,blue   
   gmt plot Jason1_WTC.txt -fi0t -St0.2c -W0.2p,green 
   gmt plot Jason2_WTC.txt -fi0t -Ss0.2c -W0.2p,black 
   gmt plot Jason3_WTC.txt -fi0t -Sd0.2c -W0.2p,lightblue 
   REM 绘制第三个图
   gmt subplot set 2 -A(C)
   gmt basemap -R1991T/2020T/-0.155/0 -JX? -Bxaf+l"year" -Byaf+l"IC (m) "  -BWSrt
   gmt plot TP_IC.txt -fi0t -Sc0.15c -W0.2p,blue    
   gmt plot Jason1_IC.txt -fi0t -St0.2c -W0.2p,green 
   gmt plot Jason2_IC.txt -fi0t -Ss0.2c -W0.2p,black 
   gmt plot Jason3_IC.txt -fi0t -Sd0.2c -W0.2p,lightblue
 gmt subplot end
gmt end show

知识点： -M设置为0.1c/-0.4c 子图间隔有最小值，此时设置间隔为负值可以继续变小。
成图：

参考：GMT-subplot