# Re: [ferret_users] converting depth cordinated into density (sigma) cordinate

 Hi, The method would be the same. You need an _expression_ that relates the units of Z axis to the other; it doesn't matter what is being converted to what.  The conversion from one to another would depend on the data; perhaps others can write in with references you might use. Ansley On 1/16/2017 7:47 PM, binny ra wrote: Hi ferreters Thank you Ansley. This is a very good FAQ that is solving some of my issues but is there a way to convert Pressure(dbar) axis to the Z (m) axis ? This is the detail of my data use salt_rg.nc sh da currently SET data sets: 1> ./salt_rg.nc  (default) name     title                                               I         J              K         L          M         N SALT     SALT_RG[L=100]                   1:360     1:130     1:58      1:152     ...       ...    sh gr salt     GRID GJP1  name       axis                                  # pts           start                                 end                      subset  LONGITUDE LONGITUDE               360mr       20.5E                            19.5E(379.5)           full  LATITUDE  LATITUDE                        130 r     64.5S                                64.5N                   full  PRESSURE  DEPTH (dbar)                58 i-         2.5                                  1975                    full  TIME      TIME                                    152 i   16-JAN-2004 05:14    16-AUG-2016 04:28       full  normal    E  normal    F {0,5,10,20,30,50,75,100,125,150,200,250,300,400,500,600,700,800,900,1000,1100,1200,1300,1400,1500,1750,2000} these are the depth levels in meters on which i want my data regards, Binny On Sat, Jan 14, 2017 at 4:36 AM, Ansley C. Manke wrote: Hi, Another place to search is the FAQ's.  What I do is open up the FAQ page and use my browser's search capability. Here's the one you need: http://ferret.pmel.noaa.gov/Ferret/faq/depth-axis-to-density-axis On 1/12/2017 8:38 PM, binny ra wrote: Dear Ferreters I think ferret is capable enough to convert depth co-ordinates (m) into density cordinates (kg/m^3) but how i don't know and i searched the mail archives but found nothing regarding this. this is the description of my data and details what I am looking for. i am having data of Potential temperature (PT), Salinity (S) and potential density (PD) all are from 0-2000 m in depth (Z), Lon(X), Lat (Y) and Time (t). So my data is PT(X,Y,Z,t), S(X,Y,Z,t) and PD(X,Y,Z,t). Now I want PT(X,Y,PD,t), S(X,Y,PD,t) and Z(PD) i.e. I want temperature and salinity as a function of density rather then depth. so that i can make depth section fill plot of temperature and salinity and overlay contours of density on it. I am badly struck in this problem as there is no such link in the mail archive. please help me out for this problem regards, Binny

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