On the vertical accuracy of the ALOS world 3D-30m digital elevation model

In this contribution, we assess the vertical accuracy of the Advanced Land Observing Satellite (ALOS) World 3D 30 m (AW3D30) digital elevation model (DEM) using the runway method (RWYM). The RWYM utilizes the longitudinal profiles of runways which are reliable and ubiquitous reference data. A reference dataset used in this project consists of 36 runways located at various points throughout the world. We found that AW3D30 has a remarkably low root mean square error (RMSE) of 1.78 m (one sigma). However, while analysing the results, it has become apparent that it also contains a widespread elevation anomaly. We conclude that this anomaly is the result of uncompensated sensor noise and the data processing algorithm. Also, we note that the traditional accuracy assessment of a DEM does not allow for identification of these type of anomalies in a DEM.