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  • Writer's pictureDirk

The world’s mountains - new online tool

Mountains occupy between 12 and 31 percent of the land surface of the globe, are home to diverse populations, ecosystems, and wildlife, and are a key provider of essential resources. But despite their importance, attempts to scientifically define and map mountain regions worldwide have been limited up to now. A new online tool gives the most detailed view of the world’s mountains yet. The Global Mountain Explorer, just recently launched, is a new, web-based tool that allows users to explore mountain regions in greater detail than ever before. Harnessing the best available data, the tool provides information ranging from global mountain distribution to local topography at a resolution 16 times greater than has been achieved in previous mapping efforts. In doing so, it is hoped that this tool will be of use to a variety of individuals and organizations, from scientists and policymakers to hikers planning their next adventure.

P³ is dedicated to contribute data and results to such public tools so that together we can protect our mountains.

Below the four P³ Mountain ranges Pyrenees, Dhofar, Great Hinggan Mountains, Sierra Nevada. The information given in the tool are:

The K1 resource used a 1 km DEM which was processed using a combination of elevation, slope and relative relief. Relative relief, or ruggedness, is the difference between maximum and minimum elevation in a moving neighborhood analysis window (NAW) and is computed for every raster cell. The K1 layer defined six classes of mountains, where the upper three classes were defined by elevation ranges. The lower three classes were defined either by a combination of elevation and slope, or elevation and relative relief. The circular NAW for computing the relative relief used a 5 pixel (~7 km) radius for an approximate NAW size of 150 km2. While the original K1 layer was derived from a 1 km DEM, we used a global 250 m DEM (GMTED2010) and recalculated to derive a new, finer resolution K1, using the same algorithms and parameters used to calculate the original K1.

The K2 resource was developed using ruggedness as the determining factor, where any relative relief greater than 200m in the NAW was considered mountainous. The original K2 resource used a 1 km DEM and an approximately 9km2 NAW to determine relative relief and then generalized the relative relief surface to an approximately 4.5 km grid (at the equator). We then downsampled the original K2 datalayer to a 250 m resolution to match the K3 and the new K1 resolution.

The K3 resource was developed using a finer spatial resolution (250 m) DEM and feature-based extraction algorithms with variable NAW sizes used to extract a set of global Hammond landforms with 16 landform types, of which four were mountain classes. E. H. Hammond was a pioneer of landform mapping and described three parameters for distinguishing different types of plains, hills, mountains, and tablelands. The three classification parameters are slope, relative relief, and profile, where the profile parameter assesses the amount of relatively flat terrain in upland locations to delineate tablelands. The 250 m global Hammond landforms product was based on an automated extraction of classes in a GIS environment, and the K3 mountains product was an export of the four mountain classes into a global mountains datalayer.

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