Convective dynamo action may be fundamentally different between low-mass and high-mass stars due to a dichotomy in their bulk electrical conductivities relative to kinematic viscosity as characterized by the magnetic Prandtl number, Pm (Augustson et al., 2019, https://doi.org/10.3847/1538-4357/ab14ea). Magnetic Prandtl values less than unity are expected in low-mass stars with convective envelopes, while larger Pm values are more relevant for high-mass stars with convective cores. Here we investigate how the fluid’s electrical conductivity alters the behavior of a given dynamo system through a suite of 3D, spherical shell dynamo models in the strongly-forced convective regime with varied magnetic Prandtl number. We find that the fluid motions, the pattern of convective heat transfer, and the mode of dynamo generation all differ across the range 0.25 ≤ Pm ≤ 10. For example, we show that strong magnetohydrodynamics effects cause a fundamental change in the surface zonal flows: the equatorial zonal jet reverses direction for sufficiently large values of the electrical conductivity. Thus, our work further supports the importance of bulk electrical conductivity for not only sustaining dynamo action, but also for the characteristics of the large-scale convective flows that generate those dynamo fields.

We measured during the MOSAiC field experiment the snow microstructure on sea-ice from early winter to the melt season, and continued measurements with the surface scattering layer. We could measure every week 1-2 full snow profiles between 0.1-0.3 m. We extracted, mostly in-situ, cores of 48-78 mm diameter and of about 0.1 m length, and scanned with 18-28 µm resolution. The goal of these measurements is to understand the formation and metamorphism of the snowpack in detail, and to derive detailed geometrical and physical properties from the samples. We will present first examples and and overview of characteristic snow profiles from leg 1 - 4, spanning the winter, spring and melt season.

Traditional finite difference method for electromagnetic simulation is based on staggered grid, whilst researches on collocated grid are few. We present a high-order collocated-grid finite-difference method for modelling electromagnetic waves with a topographic ground surface by solving 2D time-domain Maxwell equations in curvilinear coordinates. The proposed method, incorporating curvilinear coordinates, collocated grids and MacCormack finite-difference scheme techniques, can describe the geometry of the irregular interface better and avoid the numerical scattering caused by the staircase approximation in the conventional finite-difference method for electromagnetic wavefield modelling. The first-order 2D Maxwell equations on curvilinear grids are solved by an optimized MacCormack finite-difference scheme, first presented by Hixon (1997). As the collocated grids are implemented, in which the electric and magnetic fields are discretized at the same grids, the interfacial boundary conditions need to be considered. Therefore, a novel effective interface method is presented to handle the conditions. The proposed method is verified by a series of ground penetrating radar application models, such as homogeneous space, multilayered media and buried cavity models, by comparing synthetic waveforms with independent reference solutions, such as the analytical solution, the generalized reflection/transmission method and an open-source program gprMax. Comparisons show that the proposed method does well in handling multiple reflections and curved interfaces.

Over–the–Horizon (OTH) communication is strongly dependent on the state of the ionosphere, which is susceptible to solar flares. Trans–ionospheric high frequency (HF) signals experience a strong attenuation following a solar flare, commonly referred to as Short–Wave Fadeout (SWF). In this study, we examine the role of dispersion relation–collision frequency formulations on the estimation of flare–driven HF absorption seen in Riometer observation using a data assimilation framework. Specifically, the framework first uses modified solar irradiance models (such as EUVAC, FISM), which incorporate high–resolution solar flux data from GOES satellite X-ray sensors, to compute the enhanced ionization produced during the flare events. The framework then uses different dispersion relation–collision frequency formulations to estimate enhanced HF absorption. Finally, the modeled HF absorption is compared against the data to determine which combination of dispersion relation–collision frequency formulation best reproduces the Riometer observations. From the modeling work, we find that the Appleton–Hartree dispersion relation in combination with Schunk–Nagy collision frequency profile produces the best agreement with Riometer data.

Apollo lunar missions remain the most ambitious manned spaceflights in history, five decades after their conclusion. Apollo free-return mission design atmospheric reentry speeds reached 11.1 km/s, or 98.66% of Earth escape kinetic energy. Heat shield testing at such conditions was a major challenge, requiring high-reliability science. The 1960s solution involved analytic equations with numeric simulation, both verified by hypervelocity plasma arc jet lab testing, a triple standard for reliable design. Researchers at NASA Ames used tektite specimens for the task. This mostly silicate cosmic impact ejecta melt had been blasted into space, vacuum quenched during an extended loft, and naturally ablated from a cold initial state during atmospheric entry. After carefully reproducing Australasian tektite glass, spherical samples were exposed to arc jet conditions simulating near-escape speeds and upper-atmospheric conditions. The NASA scientists were able to control ablative effects at those extreme speeds to exactly match condition-sensitive features found on the natural tektites, including anterior face ring waves and flange flattening in addition to overall mass loss. Reproducing morphologic features of naturally ablated tektite via hundreds of tests over several years allowed D. R. Chapman to tune coefficients of the heat transfer equation describing hypervelocity transit from the free molecular to the collisional regime of the upper atmospheric column. The NASA Ames team determined ablated tektite reentry speeds and vertical flight path angles, and the ‘Chapman equation’ is still used for modern spacecraft heat shield design, a win-win for NASA’s Apollo program. In an error of omission, the same team never accounted for longitude shift due to 3.5 to 11.5 hours of Australasian tektite loft at those reentry speeds in order to determine regions of possible terrestrial origin. Instead, they promoted lunar origin. Terrestrial origin of tektites became clear after lunar sample return, while lunar origin of tektites led to mistrust of Chapman’s tektite reentry conditions, a case of throwing away the baby with the ‘lunar origin’ bathwater. Today, dynamically correct assessment of the A-given-B suborbital problem reveals the Australasian tektite source as roughly coincident with the N. American Great Lakes.

The Panola Mountain Research Watershed (PMRW) is a 41-hectare, forested research catchment within the Piedmont Province of the United States (U.S.), located about 25 km southeast of Atlanta Georgia (33˚ 37’ 54” N, 84˚ 10’ 20” W). Annual precipitation (P) averages 1,250 mm (<1% as snow) and annual runoff averages 358 mm, resulting in a runoff ratio of 0.29 (based on water years 1986–2015; annual range 0.13–0.50). The PMRW is seasonally water limited which results in water deficits and long-term actual evapotranspiration (ET) is about 75% of potential ET. Recharge of storage occurs predominantly in September–March when ET is lower. The U.S. Geological Survey (USGS) initiated research at the PMRW in 1985. Early focus on the effects of acid deposition transitioned to investigating processes affecting streamflow generation and water quality as part of a network of five diverse U.S. watersheds in the USGS Water, Energy and Biogeochemical Budgets Program (1991–2016). Current research is funded by the USGS Ecosystems’ Climate Research and Development Program and is focused on the effects of droughts and climatic change on ET, soil moisture, groundwater recharge, and streamflow generation. Collaboration with many Universities have occurred throughout the study. Long-term monitoring includes P, streamflow, groundwater, soil moisture, and meteorological parameters and water quality sampling of P, streamwater, and soil water. Thirty years of monthly water budgets (including actual ET and watershed storage components) and 31 years of atmospheric deposition and streamwater solute fluxes are published in USGS ScienceBase and include supporting data. The PMRW has long water residence times despite its small size, with a volume-weighted mean streamwater transit-time of ~4.7 years but can be >10 years during dry years. The PMRW has a large dynamic (>500 mm) and total (~1,000 mm) watershed storage with a hydrologic persistence of 19-months, which is evident from the water budget response to recurring hydrologic droughts. The dominant flowpath of hillslope recharge to the riparian area and stream is through bedrock. Storm-streamwater quality response was controlled by riparian (not hillslope) groundwater. We welcome opportunities for collaborative studies, cross-site comparisons, and data sharing.

Topographic features are commonly interpreted to represent interactions between tectonic and climate-driven processes. However, recent work has highlighted how drainage reorganization from river capture may produce landscapes that resemble those generated by changing tectonic conditions and emphasized the importance of developing tools and metrics to identify the source of landscape transience (Yang et al., 2015; Whipple et al., 2017). While few studies have sought to estimate the rates and magnitudes of increased transient incision resulting from river capture (e.g. Prince et al., 2011, Yanites et al., 2013), the ability to quantify river capture-related incision is vital to improve our characterization of landscape responses to transience. This work tests the hypothesis that the observed incision and distribution of knickpoints in the Sutlej river network of the western Himalaya is the result of an ongoing transient response to a large-scale river capture event that occurred in the late Pleistocene. A combination of topographic analyses using digital elevation models, knickpoint propagation modeling, 1-D numerical incision modeling, and landscape evolution modeling are used in conjunction with new and existing field-derived data (e.g. cosmogenic radionuclide-derived erosion rates and (U-Th)/He and fission track thermochronology) to quantify the magnitude and timing of the transient landscape response. Redistribution of drainage area and the subsequent enhancement of incision along the Sutlej may explain the increased amounts of Himalayan detritus delivered to the Indus fan since 5 Ma (Clift and Blusztajn, 2005). Similar large-scale river capture events proposed throughout the Himalaya (e.g. Garzione et al., 2003; Van Der Beek et al., 2018), suggest that capture events may be a regional phenomenon inherent to the Himalayan orogen and imply that river capture may be an important contributor to the distribution of sediment along collisional margins.

Each state and district within the Chesapeake Bay watershed has cooperated with the Chesapeake Bay Program (CBP) to develop local Watershed Implementation Plans (WIPs) that identify the type and quantity of best management practices (BMPs) that, if implemented, are estimated to meet 2025 Total Maximum Daily Load (TMDL) goals for Bay water quality. However, top-down management of large regions, such as the 167,000-km2 Bay catchment, is often necessarily limited by the feasibility of providing implementation plans that are customized by watershed hydro-physiographic characteristics and socio-political considerations. The Bay simulation model divides the catchment into watersheds of approximately 350 km2 each; these watersheds become the Bay model’s smallest overland management unit. We used Bay WIP plans, local information, and a hydrologic model called Topo-SWAT to model three of these smallest-unit watersheds in more local detail. Our smallest management unit became contiguous, similarly managed, cropland areas (i.e., one or several neighboring agricultural fields) and these management units were further divided by the topographic wetness index. Our watersheds represent three distinct hydrological and geochemical regions within the Chesapeake Bay catchment, namely Appalachian Valley and Ridge – karst, Appalachian Valley and Ridge – nonkarst, and Appalachian Piedmont. We modeled three scenarios for each watershed: baseline (pre-WIP), WIP implementation, and “smarter” WIP placement where we targeted BMP placements for cost-effectiveness. We then compared results among scenarios as well as across watersheds. We are interested to see how well the models agree at the watershed outlet, discover cost-effective BMP placements within each watershed that meet WIP goals, and compare our findings across the physiographic regions to determine how they can guide regional planning.

The National Water Model (NWM) currently requires the post-processing of forecast discharges to produce forecast flood inundation maps (FIM) that support the National Weather Service’s mission of protecting life and property. Height Above Nearest Drainage (HAND) is a means of detrending digital elevation models (DEM) by normalizing elevations to the nearest, relevant drainage line (creeks, rivers, etc). It’s worthy of producing high-resolution FIMs at large spatial scales and frequent time steps using reach-averaged synthetic rating curves. Current operational capabilities support 10 meter (1/3 arc-second) spatial resolution DEMs sourced from the National Elevation Dataset (NED). The 3D Elevation Program (3DEP) managed by the United States Geological Survey (USGS) publishes a variety of gridded elevation datasets at 1 m, 3 m (1/3 arc-second), 5 m, and 10 m (1/9 arc-second) among others. While the 1/3 arc-second product provides seamless coverage across CONUS, the remaining products lack full spatial support with respect to that of the NWM. However, 3DEP is actively publishing additional data with national coverage scheduled for 2023. We seek to investigate the efficacy of assimilating higher resolution 1 m and 3 m (1/3 arc-second) data derived from light detection and ranging sensors (Lidar). These Lidar derived datasets not only represent higher horizontal resolution but also have improved vertical accuracy when compared to the NED. We seek to utilize Py3DEP from the HyRiver ecosystem of tools to retrieve 3DEP data. HAND derived FIMs will be evaluated against high-fidelity HEC-RAS 1D inundation maps for 100 year and 500 year events. Possible skill enhancements can be observed from having terrain information that better agrees with those of the benchmark HEC-RAS datasets. Lidar terrain data can better resolve fine scale features that flood inundation extents may be very sensitive to. Additionally, we would investigate mosaicing techniques to deal with processing units (hydrologic unit codes) of heterogeneous data availability. This can involve resampling DEM’s to create seamless rasters within units. Lastly, we can investigate the effect of Lidar data on synthetic rating curves as well as consider the latest hydro-conditioning techniques from GeoFlood for stream line delineation on Lidar data.

The North Brazil Current transport displays a pronounced multidecadal variability with about a 7 Sv peak-to-peak amplitude. Although it has been suggested that this variability is related to that of the Atlantic Meridional Overturning Circulation, its origin is still unknown. Here we present results of an analysis of model data from a long (200 years) simulation of a high-resolution (0.1 horizontally) version of the Parallel Ocean Program that indicates a connection between multidecadal variability in the Southern Ocean, due to the so-called Southern Ocean Mode, and multidecadal variability in the North Brazil Current. The interaction of the large-scale ocean circulation and eddies is crucial for the existence of the Southern Ocean Mode. We present the mechanisms of this teleconnection in detail, which involves the vertical displacement of isopycnals, generation of Rossby waves and meridional propagation of sea surface height and ocean heat content anomalies. In addition, we show that the same mechanism connecting Southern Ocean and North Brazil Current multidecadal variability is also found in a (200 years) simulation of a high-resolution global version of the Community Earth System Model, with the same horizontal ocean resolution of 0.1. The results provide a new mechanism for the multidecadal variability of the North Brazil Current.

Densely spaced GPR and complex resistivity measurements on a 30,000 square meters site in a region of enigmatic sinkhole occurrences in unconsolidated Quaternary sediments have featured unexpected and highlighting results from both a meteorite impact research and an engineering geology point of view. The GPR measurements and a complex resistivity/IP electrical imaging revealed extended subrosion depressions related with a uniformly but in various degrees of intensity deformed loamy and gravelly ground down to at least 10 m depth. Two principle observations could be made from both the GPR high-resolution measurements and the more integrating resistivity and IP soundings with both petrophysical evidences in good complement. Subrosion can be shown to be the result of prominent sandy-gravelly intrusions and extrusions typical of rock liquefaction processes well known to occur during strong earthquakes. Funnel-shaped structures with diameters up to 25 m near the surface and reaching down to the floating ground water level at 10 m depth were measured. GPR radargrams could trace prominent gravelly-material transport bottom-up within the funnels. Seen in both GPR tomography and resistivity/IP sections more or less the whole investigated area is overprinted by wavy deformations of the unconsolidated sediments with wavelengths of the order of 5 - 10 m and amplitudes up to half a meter, likewise down to 10 m depth. Substantial earthquakes are not known in this region. Hence, the observed heavy underground disorder is considered the result of the prominent earthquake shattering that must have occurred during the Holocene (Bronze Age/Celtic era) Chiemgau meteorite impact event that produced a 60 km x 30 km sized crater strewn field directly hosting the investigated site. Depending on depth and size of floating aquifers local concentrations of rock liquefaction and seismic surface waves (probably LOVE waves) to produce the wavy deformations could develop, when the big disintegrated meteoroid (a loosely bound asteroid or a comet of roughly estimated 1 km size) hit the ground. The observations in the Chiemgau area emphasize that studied paleoliquefaction features and wavy deformations (e.g. seismites) need not necessarily have originated solely from paleoseismicity but can provide a recognizable regional impact signature.

A transient period of climate change, characterized by a global warming of ~2.5–5°C followed by a cooling to pre-excursion conditions, occurred during the last 300 kyr of the Maastrichtian (~66.34–66.02 Ma). This instability may have played a role in destabilizing marine and terrestrial ecosystems, priming the system for abrupt extinction at the K-Pg boundary, likely triggered by a large bolide impact. This pre-K-Pg warming event has often been linked to the main phase of Deccan Trap volcanism, however large uncertainties associated with radio-isotopic dating methods of basalts, along with low sedimentation rates and hiatuses in many studied sedimentary sequences, have long hampered a definitive correlation. To complement recent advances in dating of the traps, we have generated the first complete and highest resolution (2.5–4 kyr) benthic stable δ13C and δ18O record for the final million years of the Maastrichtian using the epifaunal foraminifera species Nuttallides truempyi from ODP Site 1262, Walvis Ridge, South Atlantic, calibrated to an updated orbitally-tuned age model. We then compare our data to other previously published geochemical data from other sites in the high, middle, and low latitudes. Our data confirms that the onset of the warming event coincides with the onset of the main phase of Deccan volcanism, strongly suggesting a causal link. Furthermore, spectral analysis of our extended late Maastrichtian-Early Eocene record suggests that the onset of the warming event corresponds to a 405-kyr eccentricity minima, in contrast to many transient warming events (hyperthermals) of the Paleogene, suggesting a control by orbital forcing alone is unlikely. A peculiar feature of the event, compared to other hyperthermals, is a muted carbon cycle response during warming, which may be related to the comparatively heavier δ13C signature of volcanogenic CO2 (–7‰), compared to other sources of light carbon invoked to explain Paleogene hyperthermals. The warming event coincided with minor extinctions of thermocline-dwelling foraminifera, along with dwarfing and blooms of the opportunistic disaster genera Guembelitria, suggesting that Deccan-induced climatic instability may have played a role in priming high-stress ecosystems which were tipped over a threshold into mass extinction during bolide impact.

Compound event research has gained a lot of momentum over the past few years. Traditionally risk assessment studies used to consider only one climatic driver/ process at a time. However, it was then recognized that it is the combination of multiple drivers and their statistical dependencies that lead to aggravated, non-linear impacts. The present study investigated and quantified the preconditioning of precipitation extremes (P) by existing soil moisture (SM) anomalies. Event coincidence analysis (ECA) was employed to investigate the coupling nature between SM & P event series. The datasets used include GLDAS-2.2 CLSM model products for soil moisture and GPM IMERG V06 for gridded rainfall data. Using SM and P data from 2004-2020, we identified hot-spots of SM-P coupling over India. A statistical significance test (α = 0.05) was carried out to ensure that the observed coincidences are not by chance. Our observed results agree with the widely regarded hypothesis of stronger SM-P coupling in transitional regions between wet and dry climates. The temporal evolution of SM-P dependence over the past two decades is also investigated. Results obtained provides critical insights on the complex dynamical relationship between soil moisture and precipitation. The dependence nature unraveled has vast implications for directing future research on coupled hydro-meteorological phenomena.

The marginal sea ice zone (MIZ) is a complex interface between the open ocean and the pack ice, where ocean-ice-atmosphere interactions are extremely complex. With a width of about 100 km, similar to the grid size of many climate models, the MIZ is not resolved in CMIP5 climate scenarios. In recent years, coupled climate models have been developed with ocean components at higher resolution, such as the high resolution version of the Met Office Global Coupled Model GC3 based on the GO6 configuration of the ORCA12 1/12° ocean model. We compare the MIZ representation in a coupled simulation with a simulation using the same ocean component forced by observed atmospheric data. Biases in the MIZ position and width are of the same order of magnitude in the coupled and forced model. The sea ice edge is strongly influenced by the ocean circulation and is often found at the wrong location, even when an observed atmospheric state is used to force the model. Despite a possible mismatch between atmosphere and ice/ocean in the forced model, due to the absence of feedback between sea ice and atmospheric temperature, surface heat fluxes in the MIZ are similar in amplitude in the coupled and forced simulations.  Our analysis focuses on the Greenland Sea because it is region of deep water formation, a major control of the Atlantic Meridional Overturning Circulation and thus very important for climate scenarios. The strong interannual variability of sea ice in the Greenland Sea is examplified by the Odden tongue, a protrusion of sea ice extending northeastward away from the Greenland continental slope. The coupled model exhibits such interannual variability, with a sea ice concentration larger than observed on average. The relationship between atmosphere, ice concentration and mixed layer depth is analyzed to assess the performance of both coupled and forced 1/12° models to represent deep water formation in the Nordic seas.

Electric field mills are used popularly for atmospheric electric field measurements. Atmospheric Electric Field variation is the primary signature for Lightning Early Warning systems. There is a characteristic change in the atmospheric electric field before lightning during a thundercloud formation. A voltage controlled variable capacitance is being proposed as a method for non-contacting measurement of electric fields. A varactor based mini electric field measurement system is developed, to detect any change in the atmospheric electric field and to issue lightning early warning system. Since this is a low-cost device, this can be used for developing countries which are facing adversities. A network of these devices can help in forming a spatial map of electric field variations over a region, and this can be used for more improved atmospheric electricity studies in developing countries.

As part of the Norwegian SI-ARCTIC Program, in late summer of 2014 and 2015 acoustic data (18, 38 and 120 kHz) for the estimation of the distribution and abundance of zooplankton and fish were collected from regions west and north of Svalbard, to examine high latitude epipelagic and mesopelagic scattering structures. The deep scattering layer biological constituents were determined from vertical and oblique hauls with zooplankton nets and pelagic trawls. There was strong patchy scattering in the upper part of the epipelagic zone (<50 m) throughout the area due to 0-group fish that were particularly abundant west of the Spitsbergen Archipelago and by copepods, krill, and amphipods. The distinct Off-shelf deep scattering layer (DSL) occurred between 200 and 600 m and contained a range of larger longer lived organisms (mesopelagic fish and macrozooplankton). In eastern Fram Strait, the DSL also included larger fish close to the shelf/slope break that were associated with Warm Atlantic Water moving north towards the Arctic Ocean, but switched to dominance by species having weaker scattering signatures further offshore. The Weighted Mean Depths of the DSL were deeper (WMD >440 m) in the Arctic habitat north of Svalbard compared to those south in the Fram Strait west of Svalbard (WMD ~400 m) and the mesopelagic nautical area scattering coefficient was a factor of approximately 6-10 lower around Svalbard compared to the areas in the south-eastern part of the Norwegian Sea ~62º30’N. The DSL displayed a clear ascending and descending diel movement. The high-light WMD with respect to backscattered energy was statistically deeper than the low-light WMD for the locations studied. This behavior of the DSL was consistent both when the sun was continuously above the horizon and after it started to set on 1 September, and both in open water and sea ice covered waters.

Aquatic vegetation provides ecosystem services of great value. Its protection and restoration has become a major focus in coastal management. We seek to better understand the role of vegetation in protecting shorelines from wave energy. The motion of flexible vegetation blades can significantly reduce the drag force, which will in turn affect the wave decay. The wave decay can be characterized using an effective blade length, 𝑙𝑒, which represents the length of a rigid blade that generates the same wave damping as a flexible blade with length 𝑙. Previous studies suggest that the effective blade length ratio 𝑙𝑒/𝑙~(𝐶𝑎𝑤𝐿)^−1/4, in which Cauchy number 𝐶𝑎𝑤 defines the ratio of hydrodynamic drag to blade stiffness and the normalized blade length L is the ratio of blade length to wave orbital excursion. This laboratory research extends the existing studies and the aim of finding the link between drag force on an individual blade and wave dissipation over a meadow. Flume experiments were conducted to measure the wave decay over an artificial meadow constructed from plastic blades and wooden dowels. Another set of experiments were conducted to measure the drag force on the individual blades. It’s observed that the scaling law (force on individual blade) is able to predict the wave decay over the meadow. A correction factor was needed to account for the fact that the individual blades within the meadow shelter one another. As the stem density increases, the sheltering becomes more significant, resulting in a reduced rate of wave energy dissipation.

Turbidity currents transport vast quantities of sediment across the seafloor and form the largest sediment accumulations on Earth. These flows pose a hazard to strategically important seafloor infrastructure and are important agents for the transport of organic carbon and nutrients that support deep-sea ecosystems. Therefore, it is important to quantify the scale of these flows, the amount of sediment they transport, and the evolution of their discharge over time and space along their flow path. Two modes of flow evolution have been proposed based on experimental and numerical models. The first is termed ignition, where flows entrain seafloor sediment, becoming more voluminous and powerful and increasing their discharge. In the second mode of evolution, called dissipation, sediment falls out of suspension, so flows decelerate and lose discharge. Thus far, field-scale turbidity currents have only been measured at a handful of sites worldwide, and never in detail at multiple locations along their full course. Therefore, it has not yet been possible to determine when, where, and why flows diverge into these two modes in the deep sea, or how flow discharge varies. The ambitious multi-institution Coordinated Canyon Experiment measured turbidity currents at seven instrumented moorings along the Monterey Canyon, offshore California. Fifteen flows were recorded, including the fastest events yet measured at high resolution (>8 m/s). This remarkable dataset provides the first opportunity to quantify down-channel sediment and flow discharge evolution of turbidity currents in the deep sea. To understand whether flows ignite or dissipate, we derive total and sediment discharges for each of the flows at all seven mooring locations down the canyon. Discharges are calculated from measured velocities, and sediment concentrations are derived using a novel inversion method. We observe two distinct flow modes, as most flows rapidly dissipated in the upper reaches of the canyon, while three ran out for the full 50 km array length. We then explore why only these three flows ignited and discuss the implications for canyon and channel capacity and evolution.