Hi all, After an exchange outside the list, here are some ideas for this question -- it follows along the lines of the FAQ about making a seasonal mask that we referred to before: How can I create a seasonal mask? That FAQ was written before we had the TAX* functions such as TAX_jday. This function makes the solution easier. For a seasonl average centered on January, we want to define a variable that contains the day-of-year for the time axis, and make from that a mask where the two parts are "if jday GE Dec_1st" OR "if jday LE Feb_28th". So we'll make two masks, one for December and one for January-February, and add the two masks. As in the FAQ, I'll use reynolds_sst, which you can access as an OPeNDAP dataset: yes? use "http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/reynolds_sst_wk.nc" ! Check what we've done with a line plotThe question was also how to save the result as a yearly series. We can define a yearly time axis, centered in the middle of January for the time range of the data, and regrid the masked data to this time axis with the @AVE transformation. The result is the average for each season, one per year. yes? define axis/t=16-jan-1982:16-jan-2001:1/units=year tyear jaya kumar A wrote: Dear ferret users, |