Stack profiles or envelop for x-deviation in psxy

SODA02_17.SST.NE.temp.bound.txt (2.5 KB)
Hi everyone,
I got a problem with plotting envelop with x-deviation… Normally, the code psxy usually help us to deal with y-deviation and I also success to do that. However, when it comes to x-deviation as the figure shown here, I cannot do that. Even though I saw in "psxy description with L command " they also mention about x-deviation, but i still cannot figure out how to do that.
Please help to overcome this. Thanks a lot.