The IGS plays a significant role in promoting, establishing and the densification of a global reference system. Moreover, coordinates published and distributed by the IGS are used in numerous scientific applications, ranging from plate tectonic studies to atmospheric sounding. In contrast, since the beginning of the GPS era several studies have revealed the uncertainty in the GPS height component. Especially when studying sea level changes, where the GPS height of the benchmark is used for defining an absolute sea level datum, problems occur when correcting the time series for height changes of the benchmark.
Addressing the height component in routine computation and establishing and maintaining new geodetic ties to tide gauge systems will be further an important contribution to climate change studies. With the TIGA Working Group as described in the Call for Participation the IGS will again provide its expertise to a new field of scientific application.
In December 2011 the IGS Governing Board accepted the change of the TIGA Pilot Project to the TIGA Working Group. A Call for Participation was issued on January 16th, 2011.