time averaging question

[Charles Seman]

Hi Everyone,

Listed below are the results from a GrADS session:
ga-> q dims
Default file number is: 2
X is fixed     Lon = 167.4  X = 1
Y is fixed     Lat = 8.6  Y = 1
Z is fixed     Lev = 5.375  Z = 22
T is fixed     Time = 06Z24JUL1999  T = 1
ga-> d 86400*ave(thlsf,time=25Jul,time=14Sep)
Averaging.  dim = 3, start = 217, end = 14905
Result value = -1.9949
ga-> d ave(86400*thlsf,time=25Jul,time=14Sep)
Averaging.  dim = 3, start = 217, end = 14905
Result value = -1.9949
ga-> d ave(86400*thlsf,t=2,t=15048)
Averaging.  dim = 3, start = 2, end = 15048
Result value = -2.03143
ga-> d 86400*ave(thlsf,t=2,t=15048)
Averaging.  dim = 3, start = 2, end = 15048
Result value = -2.03143
ga-> d 86400*ave(thlsf,t=2,t=15049)
Averaging.  dim = 3, start = 2, end = 15049
Result value = -2.03182
ga-> d ave(86400*thlsf,t=2,t=15049)
Averaging.  dim = 3, start = 2, end = 15049
Result value = -2.03181
ga-> d ave(86400*thlsf,t=1,t=15049)
Averaging.  dim = 3, start = 1, end = 15049
Result value = -1.36765
ga-> d 86400*ave(thlsf,t=1,t=15049)
Averaging.  dim = 3, start = 1, end = 15049
Result value = -2.03208
ga-> set t 1
Time values set: 1999:7:24:6 1999:7:24:6
ga-> d thlsf
Result value = -6.94475e-05
ga-> set t 2
Time values set: 1999:7:24:6 1999:7:24:6
ga-> d thlsf
Result value = -6.80988e-05
ga-> set t 3
Time values set: 1999:7:24:6 1999:7:24:6
ga-> d thlsf
Result value = -6.67501e-05

Any ideas what might be causing the discrepancy when the "t=1" data
point is put into the time average?

ga-> d ave(86400*thlsf,t=1,t=15049)
Averaging.  dim = 3, start = 1, end = 15049
Result value = -1.36765
ga-> d 86400*ave(thlsf,t=1,t=15049)
Averaging.  dim = 3, start = 1, end = 15049
Result value = -2.03208

Thanks,
Chuck

--

Please note that Charles.Seman at noaa.gov should be considered my NOAA
email address, not cjs at gfdl.noaa.gov.

********************************************************************
 Charles Seman                                Charles.Seman at noaa.gov
 U.S. Department of Commerce / NOAA / OAR
 Geophysical Fluid Dynamics Laboratory         voice: (609) 452-6547
 201 Forrestal Road                              fax: (609) 987-5063
 Princeton, NJ  08540-6649            http://www.gfdl.noaa.gov/~cjs/
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