A 180th degree and order model of the Venus gravity field from Magellan line of sight residual Doppler data

Abstract

Abstract. We present a new 180th degree and order model of and order L = 40 (Sjogren et al., 1997), instead of L = 90, as the Venus gravity field directly derived from line of sight suggested by sensitivity studies relative to the cycle 4 Magellan residual Doppler data instead of usual line of sight Magellan orbits. This lower threshold also has the advantage residual acceleration data. We discuss the influence of the a to enhance the signal-to-noise ratio in the Doppler residuals. priori covariance matrices on the deconvolution process, and The second major difference is that we directly processed the compare our results with previous solutions.

Venus Gravity: 180th Degree and Order Model

“…Figure 8 shows the correlation of the gravity and topography harmonic coefficients with the new model showing an increase in correlation beginning near degree 70 and extending for the higher degree terms with large differences from degree 90 to 120. As with the admittance, the correlations significantly increase when correlating only the near sectoral terms (the same is true for the Barriot et al (1999) model), but even for the high-order terms (n − m < 20), the correlations decrease to near zero at degree 180 indicating the loss of gravity signal in the data. There is not much benefit in extending the solution beyond degree 180.…”

“…Correlation of gravity coefficients with topography coefficients from Rappaport et al (1999). Correlations are shown for gravity fields MGNP180U (this paper) for both the full field and near sectoral terms (n − m < 20), MGNP120PSAAP (Konopliv et al 1996a), and the 180th degree line-of-sight solution of Barriot et al (1999). near Beta Regio and near 0.8 for Atla Regio and eastward to Beta. Other areas that show high correlation are Ishtar Terra (0.5) and eastern Eistla Regio (0.5), the location of several large coronae of interest.…”

“…The new solution (MGNP180U), 6. (a) RMS magnitude spectrum versus degree of the coefficient for the gravity fields MGNP180U (this paper) and MGNP120PSAAP (Konopliv et al 1996a) and the error spectrum for MGNP180U. Also shown is the Kaula rule scaled for Venus (1.2 × 10 −5 /n 2 ) and the more recent 180th degree solution of Barriot et al (1999). (b) RMS magnitude and error spectrum of MGNP180U versus order for three different degree ranges: "grav,90" corresponds to all coefficients between degrees 80 to 90, "grav,120" for degrees 110 to 120, and "grav,180" for degrees 170 to 180.…”

Recent Gravity Models as a Result of the Lunar Prospector Mission

“…In similar form to the Magellan gravity LOS investigations (e.g., Barriot et al (1998) and McKenzie and Nimmo (1997), the Doppler residuals are with respect to a higher resolution gravity model (in this case, LP100J) and thus contain the gravity signature beyond the modeled degree.…”

Modelling and Characterizing the Earth’s Gravity Field: From Basic Principles to Current Purposes

“…For Venus, a 180th degree and order model has been built, on the basis of the Magellan data [1]. The high resolution comes from highly eccentric orbits, and, as a consequence, from low altitude periapses.…”