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Hi all,
I'm a Ferret newbie and having trouble seeing where I'm going wrong with this so hoping one of you can help! I've got twice daily data (at 00:00 and 12:00) between 1st April 2004 and 20th December 2010 from which I'm trying to calculate monthly means. The first day in the time series only has one data point (at 12:00) and so to get around this I'm first calculating daily means, and then using these to calculate the monthly means using the following code. use moc_transports.nc ! firstly, define daily means (to be sure to avoid problems when there is for example only one data a day instead of two....) DEFINE AXIS/T=1-apr-2004:20-dec-2010:1/UNITS=days tdays LET daily_MOC = MOC_MAR_HC10[gt=tdays@AVE] ! calculate monthly means LET start_year = 2004 LET nyears = 7 LET indices = L[L=1:`nyears*12`] LET month = MOD(indices-1,12)+1 LET year = start_year + INT((indices-1)/12) DEFINE AXIS/UNITS=days/T0=1-jan-1900/EDGES truemonth = DAYS1900(year,month,1) LET monthly_moc= daily_MOC[gt=truemonth@AVE] However I've checked the few few days (see below) and the daily_moc calculation appears to be averaging the two values for the specific day along with the second value from the previous day which is not what I want, but I can't figure out where I'm going wrong. yes? list moc_mar_hc10[l=1:11] VARIABLE : overturning transport (Sv) FILENAME : moc_transports.nc SUBSET : 11 points (TIME) 01-APR-2004 12:00 / 1: 9.83 02-APR-2004 00:00 / 2: 10.30 02-APR-2004 12:00 / 3: 10.73 03-APR-2004 00:00 / 4: 11.11 03-APR-2004 12:00 / 5: 11.44 04-APR-2004 00:00 / 6: 11.70 04-APR-2004 12:00 / 7: 11.90 05-APR-2004 00:00 / 8: 12.05 05-APR-2004 12:00 / 9: 12.16 06-APR-2004 00:00 / 10: 12.25 06-APR-2004 12:00 / 11: 12.34 VARIABLE : MOC_MAR_HC10[GT=TDAYS@AVE] FILENAME : moc_transports.nc SUBSET : 6 points (TIME) 01-APR-2004 00 / 1: 9.83 02-APR-2004 00 / 2: 10.29 03-APR-2004 00 / 3: 11.10 04-APR-2004 00 / 4: 11.69 05-APR-2004 00 / 5: 12.04 06-APR-2004 00 / 6: 12.25 Any help on this will be greatfully received! Thanks in advance, Helen |