MERIT DEM

An alternative and global DTM dataset has been developed by Dai Yanmazaki of the University of Tokio, Japan — and collegues from the geophysical community. MERIT-DEM (Multi-Error-Removed Improved-Terrain DEM) is a dataset with global coverage — and it holds terrain elevations at 3 arc second resolution (approximately 90m at equator). The MERIT-DEM is based on a muliti-source approach, where SRTM3-DEM, AW3D-DEM, ViewFinder-DEM and ICESat data is used as data-input — and to filter, locate and correct the vertical errors from these spaceborne DEM's. The dataset indentifies and corrects errors from speckle noise, stripe noise, absolute bias and tree height bias. After the error removal, the percentage of global land areas mapped within 2m or better acurracy increased from 39% to 59%.

Data Evaluations

At EMD we have included the MERIT-DEM dataset in a evaluated the differences in the datasets through calculations on three different sites, where all relevant data except the DHM model is replaced. The results are shown in the table below, where the annual energy yields from the proposed wind farms are evaluated. The AEP from the original contour model is set to 100%; these are typically based on data from the local ordinance survey offices. The calculation model used is WindPRO/WAsP.

Availability in WindPRO

While the data-format provided by MERIT-DEM (geo-tiff's) can be read by WindPRO, the MERIT-DEM data is not directly available from within WindPRO due to the license conditions.

License Conditions

Due to these license conditions, we currently do not re-distribute the MERIT-DEM dataset. However, if it meets your requirements - and have recieved an access-password; then please visit the MERIT-DEM website and download the tiles you need.

External Links

• MERIT-DEM at University of Tokyo: http://hydro.iis.u-tokyo.ac.jp/~yamadai/MERIT_DEM/