Global plots of monthly anomalies in geoid heights

Monthly anomalies are derived by subtraction of a deterministic signal model (bias, trend, annual and semi-annual variations) from the monthly solutions. The signal model is fitted to the monthly means of all time-series in the time period 2004-2010, and extrapolated to earlier or later epochs to avoid poor quality solutions in the early or late phase of the GRACE mission to impact the signal model (each month is weighted equally).

For each spherical harmonic coefficient an individual model is fitted, the signal model is evaluated at the middle epochs of the monthly solutions and then the spherical harmonic coefficients are expanded into global grids, applying a 400 km Gauss filter.

Anomalies over continents are mainly due to non-periodic hydrological signals or non-linear mass trends in polar regions. These should be consistent in all time-series. Anomalies over the oceans are dominated by noise and allow for a rough noise assessment of the different time-series.

month	AIUB	CSR	GFZ	GRGS	ITSG
200204
200205
200208
200209
200210
200211
200212
200301
200302
200303
200304
200305
200307
200308
200309
200310
200311
200312
200401
200402
200403
200404
200405
200406
200407
200408
200409
200410
200411
200412
200501
200502
200503
200504
200505
200506
200507
200508
200509
200510
200511
200512
200601
200602
200603
200604
200605
200606
200607
200608
200609
200610
200611
200612
200701
200702
200703
200704
200705
200706
200707
200708
200709
200710
200711
200712
200801
200802
200803
200804
200805
200806
200807
200808
200809
200810
200811
200812
200901
200902
200903
200904
200905
200906
200907
200908
200909
200910
200911
200912
201001
201002
201003
201004
201005
201006
201007
201008
201009
201010
201011
201012
201102
201103
201104
201105
201107
201108
201109
201110
201111
201112
201201
201202
201203
201204
201206
201207
201208
201209
201211
201212
201301
201302
201304
201305
201306
201307
201310
201311
201312
201401
201403
201404
201405
201406
201408
201409
201410
201411
201501
201502
201503
201504
201505
201507
201508
201509
201512
201601
201602
201603
201605
201606
201607
201608
201611
201612
201701
201703
201704
201705
201706