Which are the highest peaks in the US Arctic? Fodar settles the debate

Abstract

Abstract. Though an outstanding achievement for their time, the United States Geological Survey (USGS) topographic maps of the eastern Alaskan Arctic nonetheless contain significant errors, and in this paper we address one of them. Specifically, USGS maps of different scale made in the late 1950s alternate between Mt. Chamberlin and Mt. Isto as the tallest peak in the US Arctic. Given that many of the peaks here are close in height and covered with glaciers, recent climate change may also have changed their height and their order. We resolved these questions using fodar, a new airborne photogrammetric technique that utilizes structurefrom-motion (SfM) software and requires no ground control, and validated it using GPS measurements on the peaks as well as airborne lidar. Here we show that Mt. Chamberlin is currently the third tallest peak and that the order and elevations of the five tallest mountains in the US Arctic are Mt. Isto (2735.6 m), Mt. Hubley (2717.6 m), Mt. Chamberlin (2712.3 m), Mt. Michelson (2698.1 m), and an unnamed peak (2694.9 m); these heights are relative to the NAVD88 GEOID12A vertical datum. We find that it is indeed plausible that this ranking has changed over time and may continue to change as summit glaciers continue to shrink, though Mt. Isto will remain the highest under current climate trends. Mt. Isto is also over 100 m taller than the highest peak in Arctic Canada, making it the highest peak in the North American Arctic. Fodar elevations compared to within a few centimeters of our ground-based GPS measurements of the peaks made a few days later and our complete validation assessment indicates a measurement uncertainty of better than ±20 cm (95 % RMSE). By analyzing time series of fodar maps, we were able to detect topographic change on the centimeter level on these steep slopes, indicating that fodar can be used to measure mountain snow packs for water resource availability or avalanche danger, glacier volume change, and slope subsidence, as well as many other applications of benefit to society. Compared to lidar, the current state-of-the-art airborne topographic mapping, we found this SfM technique as accurate, more useful scientifically, and significantly less expensive, suggesting that fodar is a disruptive innovation that will enjoy widespread usage in the future.

An Arctic watershed observatory at Lake Peters, Alaska: weather–glacier–river–lake system data for 2015–2018

“…These data were acquired using a Nikon DSLR attached to a survey grade Global Navigation Satellite System (GNSS) on board a manned aircraft, providing photocenter position to 10 cm or better and thus eliminating the need for ground control. Accuracy within this steep moun- tain environment was found to exceed 20 cm horizontally and vertically (Nolan and DesLauriers, 2016), without the use of ground control. Data acquisition methods are described in detail in Nolan et al (2015).…”

“…The third tallest peak in the range, Mount Chamberlin (2712 m a.s.l. ; Nolan and DesLauriers, 2016) lies 3 km east of Lake Peters.…”

Thaw slump activity measured using stationary cameras in time-lapse and Structure-from-Motion photogrammetry

“…The locations of the trail cameras to their tops (the offset was then subtracted to the center of lens for each camera) were surveyed using a Leica GS14 Performance Smart Antenna dGPS because it has been demonstrated that accurate SfM models can be generated from only the known camera positions and orientations, called direct georeferencing (Hugenholtz et al 2016;Nolan and DesLauriers 2016). Targets were also positioned above the headwall of the slumps (visible in the field of view of the cameras because the terrain slopes upward) to provide additional anchoring points.…”

3‐D uncertainty‐based topographic change detection with structure‐from‐motion photogrammetry: precision maps for ground control and directly georeferenced surveys

“…An alternative is ‘direct georeferencing’, in which control is provided through measurements of camera orientations only (Cramer et al , ; Förstner et al , ). By not requiring ground‐based measurements, the direct approach has a critical advantage for aerial survey over hazardous terrain, and has been shown capable of measurement precisions of order 0·1 m for piloted SfM‐based surveys with survey‐grade GPS synchronised with image capture (Nolan et al , ; Nolan and DesLauriers, ). However, for most current consumer UAVs, precise directly georeferenced work is prevented by their use of low‐quality, multi‐metre precision, on‐board GPS (Carbonneau and Dietrich, ) but survey‐grade GPS is being increasingly installed (Bláha et al , ; Chiang et al , ; Rehak et al , ; Turner et al , ; Eling et al , ; Gabrlik, ; Mian et al , ; Hugenholtz et al , ) and such systems are likely to develop into widespread, invaluable tools for geomorphological research.…”