Hello Shu, I am aware of this behavior with GDCROSS and am testing a new flag in the user input to force data display to the surface rather than to the ground surface. I will update you when I have something for you to try. Michael Unidata > Hi, > There is a problem when plotting PV contours in theta coordinate by gdcross. > The contour lines are sometimes discrete (discontinuous) down near the > surface (the attachment is an example). Can you please help me solve this > problem? Thank you so much! > Sincerely, > Shu Meir Wang > Ticket Details =================== Ticket ID: EYQ-721772 Department: Support GEMPAK Priority: Emergency Status: Open