风场矢量图 低空急流图

nicocle

请教大神们，我这张图想突出急流部分，想把12M/S以下的风速箭头去掉要怎么弄啊。这是我的GS文件~~帮帮忙呀。我加了那个'set cmin 12'也没有用呀？

'set gxout contour'
'set display color'
'set lev 850'
'set mpdset hires'
'define u=UGRDprs'
'define v=VGRDprs'
'define fs=mng(u,v)'
'set ccolor 3'
'set cthick 1'
'set arrscl 0.5 8'
'set arrowhead 0.05'
'set mpdset hires'
'set cthick 6'
'set cterp on'
'set xlopts 1 6 0.20'
'set ylopts 1 6 0.15'
'set xlint 10' ;
'set ylint 10'
'set map 1 1 6'
'set mproj proj'
'set grads off'
'set cmin 12'
'd UGRDprs;VGRDprs'

river

使用maskout命令。如果要用set cmin 12的话，display应该是'd UGRDprs;VGRDprs;mag(UGRDprs,VGRDprs)'，但是这样的话，风矢量都会变成彩色的

nicocle

river 发表于 2015-5-8 19:07
使用maskout命令。如果要用set cmin 12的话，display应该是'd UGRDprs;VGRDprs;mag(UGRDprs,VGRDprs)'，但 ...

我想做成这种效果，你看。，绿色是风向标，他只显示了小于12M/S的风向标，  红色阴影是588等值线范围，这个我不需要。只要绿色的那些效果，不知道要怎么修改GS？

river

nicocle 发表于 2015-5-9 12:18
我想做成这种效果，你看。，绿色是风向标，他只显示了小于12M/S的风向标，  红色阴影是588等值线范围，这 ...

你去看看官方用法就好了
maskout

maskout(expr,mask)

Wherever the mask values are less than zero, the values in expr are set to the missing data value.

Works with gridded or station data. Where mask values are positive, the expr values are not modified. Thus the result of maskout is data with a possibly increased number of missing data values. The maskout function, in spite of its apparant simplicity, is extremely useful.

Usage Notes

Examples

See the Examples for the const function for a description of using maskout to calculate the percentage of the globe covered by precipitation.
The maskout function can be used to cause part of the data to be ignored while doing another calculation. For example, if we have a land-sea mask, where sea values are negative, and we want to take some areal average of a quantity only over land:
d aave(maskout(p,mask.2),lon=0,lon=360,lat=0,lat=90)
People frequently have trouble using a mask grid, because it is often put into a seperate file, and given some arbitrary date/time and level. Thus, it is often necessary to locally override the dimension environment while using the mask grid:
d aave(maskout(p,mask.2(t=1)),lon=0,lon=360,lat=0,lat=90)
would probably be how Example 2 would have to be expressed in order to work, with the local override of t=1 specified on the mask data. See the documentation on how GrADS evaluates expressions within the dimension environment for more information.

jody

上面解释的很详细，在研究一下

初翠翠

谢谢分享，好好学习