Terms of Reference
The accuracy and precision of current space geodetic techniques are such that displacements due to non-tidal surface mass loading are now measurable in many cases. So data analysts have increasing interest in applying displacement corrections to their geodetic results in order to remove the geophysical loading effects. Unfortunately, doing so can introduce undesirable errors into coordinate times series and thus into the ITRF itself if the corrections are not computed or applied with utmost care. Problems that are sometimes encountered include: a proliferation of different (and sometimes erroneous) loading models; use of various different reference frames not always well suited to the geodetic reductions; applying corrections at the observation level versus longer-period a-posteriori average corrections; attributes of the geophysical loading models such as a lack of mass conservation or other errors. The goal of this working group is to investigate procedures to ensure that suitable environmental corrections are available to users and that the optimal usage is made.