Hydrological Excitation of Polar Motion Derived from GRACE Gravity Field Solutions

Table 1

Amplitude and phase of seasonal variations estimated from geodetic residuals (G-A-O), GRACE, CPC, and GLDAS-based excitations. For the annual variations, we note that GRACE-based excitation reach a better agreement in amplitude with geodetic residuals than the models.^a

	Annual		Semiannual
	Amplitude	Phase	Amplitude	Phase
	mas	degree	mas	degree
𝜒1 G-A-O	7.9±1.1	23±8	1.3±1.2	319±54
𝜒1 CPC	3.9±0.3	3±4	1.2±0.3	125±16
𝜒1 GLDAS	2.2±0.3	311±9	1.1±0.3	120±18
𝜒1 GRACE	9.0±0.7	345±4	1.2±0.6	180±27
𝜒2 G-A-O	8.6±1.5	20±10	4.2±1.2	90±16
𝜒2 CPC	13.0±0.4	18±2	1.9±0.5	156±13
𝜒2 GLDAS	2.6±0.4	2±10	1.7±0.6	129±19
𝜒2 GRACE	10.0±1.1	27±6	1.6±0.9	174±32

^aThe reference date for the phase is 2004 January 1, 0h UTC.