Hi Jian, If the dataset doesn't have the right attribute, you can always tell Ferret to treat it the way you want. If your data should have the "ocean" point of view, which is positive=down from the surface, you can say set axis/depth `variable,return=zaxis`or if it's an "atmospheric" style dataset, with positive=up, then you can say cancel axis/depth `variable,return=zaxis`These can be used in any script where the variable has a Z axis. If the dataset is already set up correctly, the commands won't cause any trouble, and if the correct attribute is not in the file, or if it is there, but set to the wrong value, it will fix it. Ansley Jian Ma wrote: Hi All, I was always confused with the vertical coordinate of nc files. The attribute "down" or "up" troubles me a lot. Is there any method in ferret to correctly plot no matter what is defined in the nc file? Or any method to reverse it in the nc file without rewrite it using fortran? Thank you very much, Tony |