modelling and prediction of the fcn
DESCRIPTION
Journées 2005. Syst è mes de Référence Spatio-Temporels. Modelling and prediction of the FCN. Maciej Kalarus 1 Brian Luzum 2 S é bastien Lambert 2 Wiesław Kosek 1. 1 Space Research Centre, Polish Academy of Sciences 2 United States Naval Observatory. Warsaw, 19-21 September 2005. - PowerPoint PPT PresentationTRANSCRIPT
Modelling and predictionof the FCN
Maciej Kalarus 1
Brian Luzum 2
Sébastien Lambert 2
Wiesław Kosek 1
Journées 2005Systèmes de Référence Spatio-Temporels
Warsaw, 19-21 September 2005
1 Space Research Centre, Polish Academy of Sciences2 United States Naval Observatory
Input data
Modelling and prediction of the FCN
Atmospheric Angular MomentumNCEP/NCAR (1984 - August 2005) four-times daily datareanalyses
Nutation residualsIERS C04 (1984 - August 2005) daily dataIAU 2000
Gravity field C20
Cox & Chao (1984 - December 2002) variable
2/9
Wavelet analysis
Complex Morlet Wavelet
-1 .0
-0 .5
0.0
0.5
1.0 Re ()Im ()
t
bc
b fttfi
ft
2
exp 2exp1Ψ
fb – bandwidth parameterfc – wavelet centre frequency
T - dilation parameter (scale) ti - translation parameter (space)
dttzTtt
TtT ii ˆ 1),(ˆ
W
Complex Wavelet Transform Coefficients
Modelling and prediction of the FCN 3/9
Wavelet analysis of the nutation residuals
1986 1988 1990 1992 1994 1996 1998 2000 2002-600-550-500-450-400-350-300
tTtT ,ˆmod, WA am
plitudehigh
low
Wavelet transform modulusP
erio
d [d
ays]
TttT
dtdtT 2,ˆarg, WGGradient of the phase
Per
iod
[day
s] +
-
0
1986 1988 1990 1992 1994 1996 1998 2000 2002-600-550-500-450-400-350-300 +
-
0
1986 1988 1990 1992 1994 1996 1998 2000 2002-600-550-500-450-400-350-300 +
_
0
1986 1988 1990 1992 1994 1996 1998 2000 2002-600-550-500-450-400-350-300
442.3
Modelling and prediction of the FCN 4/9
FCN - model
aMJDbfiAFCN FCNnMJD 2exp
200004 IAUCoriginalstd
residualsstd 0.87dX 0.91dY
Level of the residuals
epoch An[as]sin cos
01-Jan-198501-Jan-198601-Jan-198701-Jan-198801-Jan-198901-Jan-199001-Jan-199101-Jan-199201-Jan-199301-Jan-199401-Jan-199501-Jan-199601-Jan-199701-Jan-199801-Jan-199901-Jan-200001-Jan-200101-Jan-200201-Jan-200301-Jan-200401-Jan-2005
-166.370 -208.422 -219.178 -100.623-215.352 - 15.716 3.591 72.035 91.281 69.309 58.881 38.750 123.360 107.109 59.529 38.284- 75.214 - 77.095-133.172 - 95.037-165.210 87.276 21.833 56.794 208.980 167.002 168.486 159.484 115.488 75.739 112.588 8.222 60.086 25.473 12.903 4.079 102.449 125.502 203.734 61.128 24.683 42.205
TFCN=442.3days
1984 1988 1992 1996 2000 2004
-1000
0
1000
1984 1988 1992 1996 2000 2004
-1000
0
1000
[as]
[as]
dXMHB2000
dYMHB2000
Modelling and prediction of the FCN 5/9
Prediction of the FCN model
Modelling and prediction of the FCN 6/9
dX dY
Distribution of the prediction errors for 180 days in the future
0 50 100 150 2000
5
10
[%]
[as]
90%0 50 100 150 200
0
5
10
[%]
[as]
90%
RMS prediction error
0 20 40 60 80 100 120 140 160 1800
20406080
[as]
[days]
dXdY
error computed in 1986 – 2004error computed in 1986 – 2004
Possible excitation of the FCN
FCN period
Gravity field C20
nino4El Niño event 1997/98
-1-0.5
00.5
1
-480-440-400
[years]1986 1990 1994 1998 2002
-2
0
2
r=0.84
r=0.46[days][C 0] *10 -10
Modelling and prediction of the FCN 7/9
AAM annualoscillation
1986 1990 1994 1998 2002350
360
370
380[days]
[years]
velocitypressure
FCNannual AAMpWavelet
transformmodulus
[years]1986 1990 1994 1998 2002
r=-0.87
high
low
ConclusionsCharacteristic of the FCN model
- variable amplitude and period (phase)
- apparent relationship to geophysical phenomena
- mean prediction error - 70-80as for 180 days in the future
- earthquakes (T. Shirai, T. Fukushima)
- anomalous fluctuations in the core (C. M. Cox, B. F. Chao)
Other possible sources of excitation- subpolar glacial melting (J. O. Dickey, S. L. Marcus, O. de Viron, I. Fukumori)
Modelling and prediction of the FCN 8/9
Possible excitation of the FCN
Impulse excitation
- global mass redistribution
- perturbations of the annual atmospheric and oceanic circulation
- land hydrology
Thank you for your attention
Acknowledgements:This research has been partially supported by the Descartes-Nutation project.