<p>We present a method of analysing inter-satellite tracking data for detecting short-term (sub-monthly) gravitational changes from GRACE and GRACE Follow-On.&#160; The method is based on the residual range-rate data with respect to the reference range-rate computed with dynamic orbital state vectors.&#160; Then, we apply a numerical differentiation to compute range-acceleration residuals.&#160; We found that the range-acceleration residuals are near-perfectly correlated with the line-of-sight gravity difference (LGD) between two spacecrafts and the transfer (admittance) function between them can be determined regardless of time and space (Ghobadi-Far et al., 2018, JGR-Solid Earth, https://doi.org/10.1029/2018JB016088).&#160; The transfer function, to be applied directly to range-acceleration residuals, enables accurate LGD determination with the error of 0.15 nm/s^2 over the frequency band higher than 1 mHz (5 cycles-per-revolution), whereas the actual GRACE measurement error is several times larger.</p><p>In this presentation, we present two new geophysical applications to examine high-frequency gravitational changes at times scales of significantly less than one month; Gravitational observation of tsunamis triggered by the 2004 Sumatra, 2010 Maule, and 2011 Tohoku earthquakes and transient gravitational changes due to Earth&#8217;s free oscillation excited by the 2004 earthquake. &#160;Lastly, we present new results from GRACE Follow-On KBR and LRI inter-satellite ranging data.&#160;</p>
The satellite along-track analysis in planetary magnetism
