TY - JOUR
T1 - Frequency-dependent atmospheric pressure admittance of superconducting gravimeter records using least squares response method
AU - Abd El-Gelil, Mahmoud
AU - Pagiatakis, Spiros
AU - El-Rabbany, Ahmed
N1 - Funding Information:
This research was financially supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada and by the GEOIDE National Centre of Excellence. We thank J.-P. Boy for making available to us the global atmospheric correction and two anonymous reviewers for their constructive criticism and comments.
PY - 2008/9
Y1 - 2008/9
N2 - Atmospheric pressure is one of the largest environmental noise sources in surface gravity observations. This effect is usually removed by two different methods that are based on the availability of pressure data and their temporal and spatial distribution. The first method is based on a physical approach by either convolving the global surface (2D) pressure field with an appropriate Green's function or by using a 3D spherical model for attraction determination. The second method determines a transfer function between atmospheric pressure and gravity, known as barometric pressure admittance. In this paper, we focus on the second method by adopting an alternative approach for the determination of the pressure admittance that is based on the least-squares (LS) product spectrum of the atmospheric pressure and gravity time series. It represents a smooth gravity response to air pressure fluctuations in specific frequency bands (frequency-dependent admittance) with a magnitude of about 0.293μ Gal/mbar in the low-frequency band and 0.443μ Gal/mbar in the high-frequency band. This transfer function is derived from a 1-year data set recorded at the Canadian Superconducting Gravimeter Installation (CSGI; Cantley, Canada). The results show that the frequency-dependent pressure admittance reduces the quadratic norm of the gravity residuals by 95.4% while the physical approach correction which is based on the global atmospheric data reduces it by 92.2%. In addition, the frequency-dependent admittance shows an obvious improvement in the coherence spectrum.
AB - Atmospheric pressure is one of the largest environmental noise sources in surface gravity observations. This effect is usually removed by two different methods that are based on the availability of pressure data and their temporal and spatial distribution. The first method is based on a physical approach by either convolving the global surface (2D) pressure field with an appropriate Green's function or by using a 3D spherical model for attraction determination. The second method determines a transfer function between atmospheric pressure and gravity, known as barometric pressure admittance. In this paper, we focus on the second method by adopting an alternative approach for the determination of the pressure admittance that is based on the least-squares (LS) product spectrum of the atmospheric pressure and gravity time series. It represents a smooth gravity response to air pressure fluctuations in specific frequency bands (frequency-dependent admittance) with a magnitude of about 0.293μ Gal/mbar in the low-frequency band and 0.443μ Gal/mbar in the high-frequency band. This transfer function is derived from a 1-year data set recorded at the Canadian Superconducting Gravimeter Installation (CSGI; Cantley, Canada). The results show that the frequency-dependent pressure admittance reduces the quadratic norm of the gravity residuals by 95.4% while the physical approach correction which is based on the global atmospheric data reduces it by 92.2%. In addition, the frequency-dependent admittance shows an obvious improvement in the coherence spectrum.
KW - Least squares product spectrum
KW - Least squares spectrum
KW - Pressure admittance
KW - Superconducting gravimeter
UR - http://www.scopus.com/inward/record.url?scp=53249143973&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=53249143973&partnerID=8YFLogxK
U2 - 10.1016/j.pepi.2008.06.031
DO - 10.1016/j.pepi.2008.06.031
M3 - Article
AN - SCOPUS:53249143973
SN - 0031-9201
VL - 170
SP - 24
EP - 33
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 1-2
ER -