OpenAltimetry - rapid analysis and visualization of Spaceborne altimeter data

Khalsa, S. S.; Borsa, A. A.; Nandigam, Viswanath; Phan, Minh Q.; Lin, Kai; Crosby, C. J.; Fricker, H. A.; Baru, Chaitan; Lopez, Luis Alberto

doi:10.1007/s12145-020-00520-2

Cited by 40 publications

(20 citation statements)

References 7 publications

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“…We validated our model results by comparing model output for our base run with megafan topography from ICESat-2 (Neuenschwander et al, 2020) via the OpenAltimetry platform (Khalsa et al, 2020). ICESat-2 is a continuously measuring (10 kHz, ∼ 0.7 m between points on the ground) satellite that collects vegetation-penetrating laser altimetry (Neuenschwander and Pitts, 2020).…”

Section: Base Run and Validationmentioning

confidence: 99%

The push and pull of abandoned channels: how floodplain processes and healing affect avulsion dynamics and alluvial landscape evolution in foreland basins

Martin

Edmonds

2022

Earth Surf. Dynam.

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Abstract. River avulsions are an important mechanism by which sediment is routed and emplaced in foreland basins. However, because avulsions occur infrequently, we lack observational data that might inform where, when, and why avulsions occur and these issues are instead often investigated by rule-based numerical models. These models have historically simplified or neglected the effects of abandoned channels on avulsion dynamics, even though fluvial megafans in foreland basins are characteristically covered in abandoned channels. Here, we investigate the pervasiveness of abandoned channels on modern fluvial megafan surfaces. Then, we present a physically based cellular model that parameterizes interactions between a single avulsing river and abandoned channels in a foreland basin setting. We investigate how abandoned channels affect avulsion setup, pathfinding, and landscape evolution. We demonstrate and discuss how the processes of abandoned channel inheritance and transient knickpoint propagation post-avulsion serve to shortcut the time necessary to set up successive avulsions. Then, we address the idea that abandoned channels can both repel and attract future pathfinding flows under different conditions. By measuring the distance between the mountain front and each avulsion over long (106 to 107 years) timescales, we show that increasing abandoned channel repulsion serves to push avulsions farther from the mountain front, while increasing attraction pulls avulsions proximally. Abandoned channels do not persist forever, and we test possible channel healing scenarios (deposition-only, erosion-only, and far-field-directed) and show that only the final scenario achieves dynamic equilibrium without completely filling accommodation space. We also observe megafan growth occurring via ∼100 000-year cycles of lobe switching but only in our runs that employ deposition-only or erosion-only healing modes. Finally, we highlight opportunities for future field work and remote sensing efforts to inform our understanding of the role that floodplain topography, including abandoned channels, plays on avulsion dynamics.

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Section: Base Run and Validationmentioning

confidence: 99%

The push and pull of abandoned channels: how floodplain processes and healing affect avulsion dynamics and alluvial landscape evolution in foreland basins

Martin

Edmonds

2022

Earth Surf. Dynam.

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“…The minimum temporal difference for data used in this article is a couple of weeks, and for 97.9% of the validation samples it is less than 4.5 years; the maximum being 8.3 years (Table I). ATLAS ATL08 HDF files were downloaded from the National Snow and Ice Data Center after data availability and quality was assessed though OpenAltimetry [19].…”

Section: Table I Details Of Validated Atl08 Samples Per Test Areamentioning

confidence: 99%

Validation of ICESat-2 ATL08 Terrain and Canopy Height Retrievals in Tropical Mesoamerican Forests

Ferńandez

Velikova

Glennie

2022

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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In this article, we validate Ice, Cloud, and Land Elevation Satellite2 (ICESat-2)-derived interpolated terrain elevations (h_te_interp), top of canopy elevations (h_canopy_abs), and estimated canopy heights (h_canopy) in dense tropical forests of Mexico, Belize, Guatemala, and Honduras. Data from close to 30 000 ICESat-2 ATL-08 segments are compared against parameters derived from high-density (>15 pulses/m 2 ) topographic airborne lidar (HDL) data from seven different sites with a variety of forest structure and terrain conditions, totaling 3742 km 2 of validated area. Our results indicate that in these high closure forests the range of errors (within the 5th to 95th percentiles) for these parameters vary widely, but their median and interquartile range (IQR) grow proportionally to the HDL-derived reference canopy height (rCH). The errors in h_te_interp retrieval grow in proportion to the rCH from ±2.5 m for areas with fairly low rCH (5-10 m) all the way to −10 to 24 m for areas with rCH of 40-45 m. The median of h_te_interp errors also grows proportionally to rCH and is consistently overestimated with regards to the reference. With respect to h_canopy_abs, it was observed that the errors also grow with increasing rCH but a much lower rate; the IQR is generally constrained between −5.5 and 6.0 m, while the median remains mostly uniform and independent of the rCH and underestimates the reference by −0.5-−2.0 m. The IQR of the errors in h_canopy normalized to rCH exhibits a mostly uniform behavior across the range of rCH between −33.5% and 7.0%, with the median fluctuating around an underestimation level of -16.5%.

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“…We initially used the open‐source software OpenAltimetry ( https://openaltimetry.org ; Khalsa et al., 2020 ), and examined all available ICESat‐2 tracks over the Amery doline region. Four ICESat‐2 RGTs cross the region (Figures 1b and 1c ).…”

Section: Topographic Signature Of Doline Formationmentioning

confidence: 99%

Rapid Formation of an Ice Doline on Amery Ice Shelf, East Antarctica

Warner

Fricker

Adusumilli

et al. 2021

Geophysical Research Letters

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Antarctica's ice shelves regulate the flow of grounded ice to the ocean, through a process known as buttressing (Thomas, 1979). Under stable climate conditions, ice shelves remain approximately in equilibrium, gaining mass from ice flow across the grounding line and local snowfall, and losing mass through ocean melting at their bases (year-round), iceberg calving from their ice fronts (episodic) and surface melting (principally during summer). In recent decades, some Antarctic Peninsula ice shelves have experienced greater surface melting in response to increasing atmospheric temperatures (Barrand et al., 2013;Trusel et al., 2015). This has led to more extensive melt ponds, providing sufficient water volumes to drive so-called "hydrofracturing" (Weertman, 1973), sometimes leading to ice shelf collapse via an extreme disintegrative type of calving involving multiple hydrofractures (Banwell et al., 2013;Scambos et al., 2003;van den Broeke, 2005). In these regions, flow rates of the grounded ice have increased (Rignot et al., 2004;Scambos et al., 2003), due to loss of buttressing.Antarctic surface melting has been projected to double by 2050 (Gilbert & Kittel, 2021;Trusel et al., 2015), raising concerns about the stability of other ice shelves. This has renewed interest in monitoring surface

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OpenAltimetry - rapid analysis and visualization of Spaceborne altimeter data

Cited by 40 publications

References 7 publications

The push and pull of abandoned channels: how floodplain processes and healing affect avulsion dynamics and alluvial landscape evolution in foreland basins

The push and pull of abandoned channels: how floodplain processes and healing affect avulsion dynamics and alluvial landscape evolution in foreland basins

Validation of ICESat-2 ATL08 Terrain and Canopy Height Retrievals in Tropical Mesoamerican Forests

Rapid Formation of an Ice Doline on Amery Ice Shelf, East Antarctica

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