Abstract
Many biochemical processes and dynamics are strongly controlled by terrain topography, making digital elevation models (DEM) a fundamental dataset for a range of applications. This study investigates the quality of four pan-Arctic DEMs (Arctic DEM, ASTER DEM, ALOS DEM and Copernicus DEM) within the Kalix River watershed in northern Sweden, with the aim of informing users about the quality when comparing these DEMs. The quality assessment focuses on both the vertical accuracy of the DEMs and their abilities to model two fundamental elevation derivatives, including topographic wetness index (TWI) and landform classification. Our results show that the vertical accuracy is relatively high for Arctic DEM, ALOS and Copernicus and in our study area was slightly better than those reported in official validation results. Vertical errors are mainly caused by tree cover characteristics and terrain slope. On the other hand, the high vertical accuracy does not translate directly into high quality elevation derivatives, such as TWI and landform classes, as shown by the large errors in TWI and landform classification for all four candidate DEMs. Copernicus produced elevation derivatives with results most similar to those from the reference DEM, but the errors are still relatively high, with large underestimation of TWI in land cover classes with a high likelihood of being wet. Overall, the Copernicus DEM produced the most accurate elevation derivatives, followed by slightly lower accuracies from Arctic DEM and ALOS, and the least accurate being ASTER.
Highlights
Topography is a fundamental property of the terrain that strongly influences a large number of biogeochemical processes and dynamics that take place on the Earth’s surface [1].digital elevation models (DEMs) are key datasets for studying and modellingEarth surface features and processes, of relevance for hydrology, agronomy, geomorphology, soil formation and land cover mapping [2]
For Arctic DEM, the positive bias is significantly lower compared to the values between 14.71 and 15.75 m, as reported by Glennie (2018) in Sitka, Alaska, but in the same range as those reported for Svalbard [60]
This study has analysed four freely available DEMs with pan-Arctic coverage, including Arctic DEM, Advanced Land Observing Satellite (ALOS) World 3D, ASTER GDEM3 and Copernicus, through comparison with a highly accurate digital terrain model (DTM) with 2 m grid cell size produced from airborne Light Detection and Ranging (LiDAR)
Summary
Topography is a fundamental property of the terrain that strongly influences a large number of biogeochemical processes and dynamics that take place on the Earth’s surface [1].digital elevation models (DEMs) are key datasets for studying and modellingEarth surface features and processes, of relevance for hydrology, agronomy, geomorphology, soil formation and land cover mapping [2]. A DEM is a digital representation of a terrain surface usually conceptualised as a grid, where the grid-cell values represent the elevation of a specific area relative to a reference value (e.g., sea level). Differences exist in the terminology and definitions concerning DEMs, as well as the associated terms digital surface model (DSM) and digital terrain model (DTM) [3,4,5]. The term DEM is used here as a general umbrella term for all types of elevation models, while the term DTM refers to the model representing the elevation of the bare ground, and the term DSM refers to the model representing the elevation, which includes any natural and manmade features located on the Earth surface [5,6]. DTMs are a bare-Earth model, where heights of natural or manmade features, if present, have been removed
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