Spatial and temporal power spectra of the geomagnetic field

被引:34
|
作者
McLeod, MG
机构
关键词
D O I
10.1029/95JB03042
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Spatial and temporal power spectra of the geomagnetic field are useful for stochastic inversion and optimal prediction of the geomagnetic field and its secular variation. Spherical harmonic coefficients for the field and its first time derivative were determined from magnetic observatory annual means and first differences of annual means for each year in the time interval 1910-1983. Internal spherical harmonic coefficients through degree 9 and external zonal coefficients in geomagnetic coordinates for degrees 1, 3, 5, and 7 were included in the analysis. Autocovariance functions for spherical harmonic coefficients of the geomagnetic field were estimated from these coefficients. Characteristic time constants for the estimated internal autocovariance functions depend upon both spherical harmonic degree and whether the autocovariance function is for the field or its first derivative. The characteristic time constant for the field is approximately 10,000 years divided by the square of (n+1/2), where n is the spherical harmonic degree. The characteristic time constant for the first derivative is about a factor of 10 smaller. The first time constant is thought to be related to magnetic diffusion, and the second time constant is thought to be related to core-fluid velocity correlation time. There is also a third time constant of approximately 5 years associated with the second time derivative. External autocovariance functions for degree 1 and degree 3 both show clear evidence of a solar cycle component. A simple analytic expression for the spatial and temporal power spectra of the geomagnetic field was fitted to these data and agrees well with the experimental results.
引用
收藏
页码:2745 / 2763
页数:19
相关论文
共 50 条
  • [12] Energy and Power Spectra of the Potential Geomagnetic Field since 1840
    S. V. Starchenko
    S. V. Yakovleva
    Geomagnetism and Aeronomy, 2019, 59 : 242 - 248
  • [13] Energy and Power Spectra of the Potential Geomagnetic Field since 1840
    Starchenko, S. V.
    Yakovleva, S. V.
    GEOMAGNETISM AND AERONOMY, 2019, 59 (02) : 242 - 248
  • [14] POWER SPECTRA OF GEOMAGNETIC-FIELD VARIATIONS AT SYNCHRONOUS ORBIT
    ARTHUR, CW
    MCPHERRON, RL
    LANZEROTTI, LJ
    WEBB, DC
    TRANSACTIONS-AMERICAN GEOPHYSICAL UNION, 1977, 58 (06): : 470 - 470
  • [16] POWER SPECTRA OF GEOMAGNETIC MICROPULSATIONS
    FOOKS, GF
    MORGAN, DP
    JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS, 1967, 29 (02): : 201 - &
  • [17] ANALYTICAL REPRESENTATION OF SPATIAL AND TEMPORAL VARIATIONS OF THE GEOMAGNETIC-FIELD IN THE INDIAN REGION
    ARORA, BR
    BADSHAH, VH
    SINGH, BP
    ARUR, MG
    BAINS, PS
    LAL, J
    PROCEEDINGS OF THE INDIAN ACADEMY OF SCIENCES-EARTH AND PLANETARY SCIENCES, 1983, 92 (01): : 15 - 30
  • [18] SPATIAL POWER SPECTRUM OF MAIN GEOMAGNETIC-FIELD, AND EXTRAPOLATION TO CORE
    LOWES, FJ
    GEOPHYSICAL JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY, 1974, 36 (03): : 717 - 730
  • [19] FOURIER POWER SPECTRA OF THE GEOMAGNETIC-FIELD FOR CIRCULAR PATHS ON THE EARTHS SURFACE
    ALLDREDGE, LR
    BENTON, ER
    JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY, 1986, 38 (08): : 807 - 821
  • [20] GEOMAGNETIC-FIELD FLUCTUATIONS AT SYNCHRONOUS ORBIT .1. POWER SPECTRA
    ARTHUR, CW
    MCPHERRON, RL
    LANZEROTTI, LJ
    WEBB, DC
    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 1978, 83 (NA8): : 3859 - 3865