ITSG-Grace2016 - Monthly and Daily Gravity Field Solutions from GRACE

The ITSG-Grace2016 gravity field model is the latest GRACE only gravity field model computed at Graz University of Technology, providing unconstrained monthly and Kalman smoothed daily solutions. It covers the whole GRACE time span from 2002-04 and will be continually updated. For each month of the observation period, sets of spherical harmonic coefficients for different maximum degrees (60, 90, 120) were estimated without applying any regularization. In order to resolve daily gravity field variations as detailed as possible, a set of spherical harmonic coefficients up to degree and order 40 was estimated using the Kalman smoother estimation procedure introduced by Kurtenbach et al. 2012.K-band range rates with a sampling of 5 seconds and kinematic orbits with a sampling of 5 minutes were used as observations.
The kinematic orbits of the GRACE satellites (Zehentner and Mayer-Gürr 2013, 2014) were processed using the GPS orbits and clock solutions provided by IGS. An improved attitude product derived from a combination of star camera data and angular accelerations (Klinger and Mayer-Gürr 2014) was used to estimate K-band antenna center variations (one set per month). Additionally, accelerometer scale factors were estimated per axis and day. The accelerometer bias was modelled through cubic splines with a node interval of six hours and estimated for each axis and day.
Detailed information about ITSG-Grace2016 is available at http://ifg.tugraz.at/ITSG-Grace2016.