The IAG Inter-Commission Project 1.2 “Vertical Reference Frames” (IAG ICP1.2) was established during the XXIII IUGG General Assembly (30 June - 11 July, 2003) in Sapporo, Japan. Its main purposes were to study the consistent modelling of geometric and gravimetric parameters, and to provide the fundamentals for the installation of a unified global vertical reference frame. Its activities were supported by the combined effort of the IAG Commissions 1 (Reference Frames) and 2 (Gravity Field).
After a work period of four years (2003-2007), a general concept for the definition and realization of a global vertical reference system (called also World Height System – WHS) was developed. The main aspects are documented in the Conventions for the Definition and Realization of a Conventional Vertical Reference System (CVRS). Based on the achievements of this first term, during the XXIV IUGG General Assembly (2 – 13 July, 2007) in Perugia, Italy, it was decided to extent the IAG ICP1.2 activities for a second period (2007 – 2011) with the major objective of initiating a pilot project for the WHS realization (WHS-PP). This project was to further expand and refine the reference frame infrastructure of the IAG, to provide users with information about existing vertical reference frames worldwide, and to relate the regional height systems to a global datum.
In the same way as the ITRS/ITRF provides a high precision geometrical reference frame, a consistent WHS shall provide the corresponding high precision physical reference frame for studying the system Earth. Since this is a basic requirement for the Global Geodetic Observing System (GGOS), the IAG ICP1.2 accomplishments are a fundamental input for GGOS and were the start point for the establishment of the GGOS Focus Area 1 Unified Height System.
Chair: Johannes Ihde (Germany), Alireza A. Ardalan (Iran), Carine Bruyninx (Belgium), Milan Bursa (Czech Republic), Tonie van Dam (Luxemburg), Gleb Demianov (Russia), Will Featherstone (Australia), Christopher Jekeli (USA), Adolfientje Kasenda (Australia), Bill Kearsley (Australia), Roland Klees (Netherlands), Gunter Liebsch (Germany), Markku Poutanen (Finland), Laura Sánchez (Colombia), Tilo Schöne (Germany), Steve Shipman (UK), Jaroslav Simek (Czech Republic).
During the first term (2003 - 2007) the IAG ICP1.2 was extended by: Matt Amos (Australia), Wolfgang Bosch (Germany), Alessandro Capra (Italy), Robert Cunderlik (Slovakia), Herman Drewes (Germany), Bernhard Heck (Germany), Jan Krynski (Poland), Urs Marti (Switzerland) Jaakko Mäkinen (Finland), Marcel Mojzes (Slovakia), Dan Roman (USA), Zdislav Šima (Czech Republic), Viliam Vatrt (Czech Republic), Marc Véronneau (Canada), Marie Vojtiskova (Czech Republic), Herbert Wilmes (Germany).
During the first term (2003 - 2007) the IAG ICP1.2 was partly joint by: Ruth Adams (UK), Jonas Ägren (Sweden), Susana Barbosa (Portugal),Matthias Becker (Germany), Dorata Brzezinska, Francoise Duquenne (France), Henri Duquenne (France), Jan Ferko, Joana Fernandes (Portugal), Georgia Fotopoulos (Canada), Roger Hipkin (UK), Petr Holota (Czech Republic), Jianliang Huang (Canada), Karl Heinz Ilk (Germany), Michael Kuhn (Australia), Jan Kouba (Canada), Roberto Teixeira Luz (Brazil), Jan Marsa (Czech Republic), Jürgen Müller (Germany), Diethard Ruess (Austria), Eimuntas Parseliunas (Lithuania), Martin Vermeer (Finland), Franziska Wild-Pfeiffer (Germany).
The IAG Inter-Commission Project 1.2 studied during the period 2003 – 2007 the possibilities of the definition and realization of a global vertical reference system (GVRS) based on the classical and modern observations and a consistent modeling of both, geometric and gravimetric parameters. The results of this work are documented in Conventions for the Definition and Realization of a Conventional Vertical Reference System (CVRS). In the CVRS conventions a general concept for the definition and realization of a unified, global vertical reference system is described. The CVRS conventions are aligned to the IERS 2003 Conventions. Parts of the IERS 2003 conventions are the basis for the CVRS conventions. Open topics are the establishment of an information system describing the various regional vertical reference frames and their relation to a GVRS, the determination of transformation parameters between regional vertical reference frames and the unified global height system as well as the relationships between a GVRS and the International Terrestrial Reference System.
Final report for the period 2007-2011 (Ihde J. 2011, In: Drewes H., Hornik H. (Eds.) Travaux de l'AIG 37, IAG Reports 2007-2011, 2011).
Mid-term report for the period 2007 – 2011 (Ihde J. 2009, In: Drewes H., Hornik H. (Eds.) Travaux de l'AIG 36, IAG Reports 2007-2009, 2009).
Final report for the period 2003-2007 (Ihde, J. 2007, In: Drewes H., Hornik H. (Eds.) Travaux de l'AIG 35, IAG Reports 2003-2007, 2007).
Mid-term report for the period 2003 – 2007 (Ihde J. 2005, In: Drewes H., Hornik H. (Eds.) Travaux de l'AIG 34, IAG Reports 2003-2005, 2005).