New research published in the Journal of Geodesy establishes a novel approach to measuring elevation – one that is not based on sea level. The system, aptly named the International Height Reference System (IHRS), was developed by geodetic specialists at the Technical University of Munich (TUM).
The paper explains the scientific background and theoretical concept of the new system and goes as far as to devise a strategy for implementing it. The need for a new system comes from the obvious knowledge that sea level, which is the standard starting point from which elevations are measured, is not the same at all places on Earth. The IHRS aims to address the resulting discrepancies in the current system by unifying geodetic measurements and establishing once and for all a standard “zero”.
"The introduction of an internationally valid height reference system was long overdue," says TUM researcher Dr. Laura Sánchez of the Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), who is working on the new system at the International Association of Geodesy.
As the authors explain, the IHRS introduces a gravity field-related global height system based on geopotential points. "It became possible to realize the IHRS only with the availability of global data from satellite missions such as the ESA earth observation satellite GOCE (Gravity field and steady-state Ocean Circulation Explorer)," explains Professor Roland Pail of the TUM Chair of Astronomical and Physical Geodesy (APG).
"The information gained in this way provides the basis to calculate the mean sea level for every point on Earth with the new International Height Reference System, regardless of whether it is on a continent or in an ocean, and thus to compute the internationally accepted zero level," adds Sánchez.
Thanks to the IHRS, China and Nepal have finally agreed on a measurement for Mount Everest: the governments jointly reported an elevation of 8848.86 meters. But the system isn’t only useful for establishing record-breaking elevations – it also serves a more practical need for construction projects spanning international borders. Because of this, the researchers don’t doubt that the IHRS will be quickly accepted into global practices.