MERIT DEM (SRTM-based Bare-Earth model), 2017

MERIT (Multi-Error-Removed Improved Terrain DEM) is a substantially improved near-global terrain description with 90 m (3 arc-seconds) spatial resolution (Yamazaki et al. 2017). MERIT covers almost all of Earth’s land areas within 90N-60S, except of Antarctica. Different to most other global DEM data sets, MERIT provides – in good approximation – elevations of the bare ground. This has been achieved by reducing vegetation heights (known as tree height bias) using tree density and tree height maps as auxiliary information in the production of the MERIT DEM. However, over built areas, MERIT elevations may contain a bias due to urban canopy. MERIT relies on SRTM v2.1 South of 60° latitude, ALOS AW3D North of 60° latitude, and uses elevations from Viewfinder Panoramas (VFP-DEM) to fill voids (unobserved areas) where present. For the void-filling with VFP-DEM, an average matching method has been applied by Yamazaki et al. (2017) to ensure smooth transitions. Within the SRTM data area, about 0.5 % of MERIT land cells rely on VFP-DEM. North of 60°, the contribution of VFP-DEM is about ~30 %. As a result, elevation errors previously present in the SRTM model have been reduced such that actual terrain features stand out more clearly. Geodetic information: The MERIT DEMs are vertically referenced to the EGM96 geoid and horizontally referenced to the WGS84 (World Geodetic System 1984). Further notes: The MERIT DEM mostly represents bare ground elevations, so is technically close to a digital terrain model (DTM). This makes the data set suitable for applications requiring heights of the bare ground. Example areas are hydrology, hydrodynamics, physical geodesy and geophysics. Data access: The authors freely share their model for non-commercial applications (e.g. science and education) via URL: hydro.iis.u-tokyo.ac.jp/~yamadai/MERIT_DEM/ References: Yamazaki, D., D. Ikeshima, R. Tawatari, T. Yamaguchi, F. O’Loughlin, J.C. Neal, C.C. Sampson, S. Kanae, P.D. Bates (2017), A high accuracy map of global terrain elevations, Geophysical Research Letters, Doi: 10.1002/2017GL072874