Model Parameters — sliders perturb from MLR-fitted values
2000.0
100
1.00
0.00
1.00
0.00
0.22
0.00
MLR fit pending…
Y-pole Polar Motion — IERS EOP C04
shaded region = training window
IERS observed
MLR model
Residual
Amplitude Spectrum
Hann-windowed · log period axis
Phase Plane (X vs Y pole)
Chandler-band filtered · colored by decade
2nd-Order Spectral Exploration — Semi-log (linear freq, log amplitude)
IERS X+Y avg & MLR model · 0–2.5 cyc/yr
IERS X+Y avg (observed)
MLR model
1st-order peaks (always shown)
2nd-order peaks (toggle)
Drac2 = 2×draconic alias (Chandler) · Mm = 3×anomalistic alias · Mm2 = 2×anomalistic alias · Drac2− = Chandler − (f_a−13)
Pukite Lunisolar Forcing Model
aliasing derivation
Resonator ODE: ẍ + 2ζω₀ẋ + ω₀²x = ω₀² · F(t)
Forcing: F(t) = A_d · cos²(ω_d·t + φ_d) · (1 + ε_node · cos(2π·t/T_node + φ_node))
Chandler alias: T_cw = T_yr / (T_yr/T_d − 13) / 2 ≈ 432.8 days
MLR design matrix: X = [res_cos, res_sin, cos(2πt/T_ann+φ_ann), sin(2πt/T_ann+φ_ann), cos(2πt/T_d), sin(2πt/T_d), cos(2πt/T_node), sin(2πt/T_node), 1]
Beat period: T_beat = 1/|1/T_cw − 1/T_yr| = — yrs
Forcing: F(t) = A_d · cos²(ω_d·t + φ_d) · (1 + ε_node · cos(2π·t/T_node + φ_node))
Chandler alias: T_cw = T_yr / (T_yr/T_d − 13) / 2 ≈ 432.8 days
MLR design matrix: X = [res_cos, res_sin, cos(2πt/T_ann+φ_ann), sin(2πt/T_ann+φ_ann), cos(2πt/T_d), sin(2πt/T_d), cos(2πt/T_node), sin(2πt/T_node), 1]
Beat period: T_beat = 1/|1/T_cw − 1/T_yr| = — yrs