Supraglacial dust and debris characterization via in situ and optical remote sensing methods

Supraglacial dust and debris affects many glaciologic variables, including radiative absorption, ablation, generation of supraglacial melt as well as mass flux. Earth observing satellite technology has advanced greatly in recent decades and allows for unprecedented spatial, temporal and spectral imaging of Earth’s glaciers. While remote sensing of ‘clean’ glacier ice can be done quite successfully, strategies for satellite mapping of supraglacial debris remain in development. This work provides the first visible to thermal infrared full optical spectrum satellite data analysis of supraglacial dust and debris characterization and differentiation. Dust and debris covered glaciers in the following six contrasting study regions were targeted: Iceland, Nepal, New Zealand, southern Norway, Svalbard and Switzerland. A combination of field spectrometry and surface samples of snow, ice and debris were utilized to investigate supraglacial dust and debris diversity. This in situ data served as ground truth for evaluating spaceborne supraglacial debris mapping capabilities. Glacier snow, ice and debris samples were analyzed for mineral composition and inorganic elemental abundances via the following analytical geochemical techniques: X-ray diffraction, X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry. A synoptic data set from four contrasting alpine glacier regions – Svalbard, southern Norway, Nepal and New Zealand – and 70 surface snow, ice and debris samples was presented, comparing supraglacial composition variability. Distinct supraglacial geochemical abundances were found in major, trace and rare earth elemental concentrations between the four study regions. Elemental variations were attributed to both natural and anthropogenic processes. Over 8800 glacier surface spectra were collected in Nepal, Svalbard and Switzerland, as well as from Nepal, New Zealand and Switzerland debris samples. Surface glacier debris mineralogy and moisture content were assessed from field spectra. Spaceborne supraglacial dust and debris mineral mapping techniques using visible to shortwave reflective and thermal emissive data were evaluated. Successful methods for mineral identification allowed mapping of volcanic vs. continental supraglacial debris, as well as different mineral classes within one glacier’s supraglacial debris. Granite- vs. schist-dominant debris was mapped on Khumbu glacier in Nepal. Iron-rich vs. iron-poor serpentine debris was mapped on Zmutt glacier in the Swiss Alps. Satellite emissivity derived silica mapping suggested potential use of silica thresholds for delineation of debris covered glacier extent or sediment transport and weathering processes. Satellite derived surface temperatures were compared in Iceland, Nepal, Switzerland and New Zealand glacier study regions, with results demonstrating variations in supraglacial temperatures coincident with changing mineral abundances. Consistently higher surface temperatures with increasing dust and debris cover were mapped at all four glacier study regions. Repeat supraglacial debris imagery was used to estimate ablation area velocities and particulate transport times at debris covered glaciers. Velocity derivations used in conjunction with supraglacial composition variation analysis from shortwave and thermal infrared false color composites, allowed for estimation of glacial mass flux in the Khumbu Himalayas. In short, the visible to thermal infrared satellite spectral analysis, combined with in situ spectral and geochemical ground truth data, proved that glacier dust and debris characterization is possible via satellite spectral data. Furthermore, this supraglacial dust and debris satellite characterization can be applied to a range of glaciologic studies, including thermal, mass balance and surface process interpretations on large spatial and temporal scales

The spectral and chemical measurement of pollutants on snow near South Pole, Antarctica

Remote sensing of light-absorbing particles (LAPs), or dark colored impurities, such as black carbon (BC) and dust on snow, is a key remaining challenge in cryospheric surface characterization and application to snow, ice, and climate models. We present a quantitative data set of in situ snow reflectance, measured and modeled albedo, and BC and trace element concentrations from clean to heavily fossil fuel emission contaminated snow near South Pole, Antarctica. Over 380 snow reflectance spectra (350–2500 nm) and 28 surface snow samples were collected at seven distinct sites in the austral summer season of 2014–2015. Snow samples were analyzed for BC concentration via a single particle soot photometer and for trace element concentration via an inductively coupled plasma mass spectrometer. Snow impurity concentrations ranged from 0.14 to 7000 part per billion (ppb) BC, 9.5 to 1200 ppb sulfur, 0.19 to 660 ppb iron, 0.013 to 1.9 ppb chromium, 0.13 to 120 ppb copper, 0.63 to 6.3 ppb zinc, 0.45 to 82 parts per trillion (ppt) arsenic, 0.0028 to 6.1 ppb cadmium, 0.062 to 22 ppb barium, and 0.0044 to 6.2 ppb lead. Broadband visible to shortwave infrared albedo ranged from 0.85 in pristine snow to 0.62 in contaminated snow. LAP radiative forcing, the enhanced surface absorption due to BC and trace elements, spanned from \u3c1 W m­–2 for clean snow to ~70 W m­–2 for snow with high BC and trace element content. Measured snow reflectance differed from modeled snow albedo due to specific impurity-dependent absorption features, which we recommend be further studied and improved in snow albedo models

Debris-covered glacier systems and associated glacial lake outburst flood hazards:Challenges and prospects

Glaciers respond sensitively to climate variability and change, with associated impacts on meltwater production, sea-level rise and geomorphological hazards. There is a strong societal interest in understanding the current response of all types of glacier systems to climate change and how they will continue to evolve in the context of the whole glacierized landscape. In particular, understanding the current and future behaviour of debris-covered glaciers is a 'hot topic' in glaciological research because of concerns for water resources and glacier-related hazards. The state of these glaciers is closely related to various hazardous geomorphological processes which are relatively poorly understood. Understanding the implications of debris-covered glacier evolution requires a systems approach. This includes the interplay of various factors such as local geomorphology, ice ablation patterns, debris characteristics and glacier lake growth and development. Such a broader, contextualized understanding is prerequisite to identifying and monitoring the geohazards and hydrologic implications associated with changes in the debris-covered glacier system under future climate scenarios. This paper presents a comprehensive review of current knowledge of the debris-covered glacier landsystem. Specifically, we review state-of-the-art field-based and the remote sensing-based methods for monitoring debris-covered glacier characteristics and lakes and their evolution under future climate change. We advocate a holistic process-based framework for assessing hazards associated with moraine-dammed glacio-terminal lakes that are a projected end-member state for many debris-covered glaciers under a warming climat

Changing glaciers in the Brooks Range and western Chugach Mountains, Alaska: mass loss, runoff increase, and supraglacial volcanic tephra coverage

Thesis (Ph.D.) University of Alaska Fairbanks, 2020Glaciers in Alaska cover over ~87,000 km² (~ 6 % of the state) with most glaciers thinning and retreating at an increasing rate. The thinning and retreating of glaciers worldwide can have an immediate socio-economic implication in addition to the longer-term glacier meltwater contribution to sea level rise. This dissertation investigated Alaskan glaciers in the Brooks Range for mass loss and area reductions over the period 1970-2001 (Chapter 2), historic mass balance and runoff for Eklutna Glacier, located in western Chugach Mountains, using a temperature index model over 1984-2019 period (Chapter 3), and the persistence of tephra from a volcanic eruption of Mt. Spurr in 1992 on seven western Chugach Mountain glaciers (Chapter 4). Glaciers in the Brooks Range in Arctic Alaska (> 68° N) are important indicators of climate change and provide information on long-term climate variations in an area that has few high elevation meteorological stations. Digital elevation models (DEMs) reconstructed from topographic maps were differenced from an interferometric synthetic aperture radar DEM to calculate the volume and mass changes of 107 glaciers (42 km²). Over the period 1970-2001, total ice volume loss was 0.69 ± 0.06 km³ corresponding to a mean (area-weighted) specific mass balance rate of -0.54 ± 0.05 m w.e. a⁻¹ (± uncertainty). The arithmetic mean of all glaciers' specific mass balance rates was -0.47 ± 0.27 m w.e. a⁻¹ (± 1 std. dev.). A subsample of 36 glaciers found a 26 ± 16 % mean area reduction over ~35 years. Alaska's largest city, Anchorage, is critically dependent upon the melt water of Eklutna Glacier (29 km²) for both drinking water and hydropower generation; however, the glacier is rapidly retreating. We used a temperature index model to reconstruct the glacier's mass balance for the period 1985-2019 and quantify the impacts of glacier change on runoff. Eklutna Glacier experienced a significant annual mean surface mass balance negative trend (-0.38 m w.e. Decade⁻¹). Mean annual cumulative melt increased by 24 % between the 1985-93 and 2011-19 period. Additionally, the day of the year when 95% of annual melt has occurred was eight days later in the later time period than in the earlier period, demonstrating a prolongation of the melt season. The modeled mean annual discharge increased at a rate of 0.2 m decade⁻¹. This indicates that peak water, i.e. the year when annual discharge starts decreasing as the glacier becomes smaller, has not been reached. The past increases in runoff quantity and melt season length provide opportunities for water resource managers that must be balanced against future decreased runoff as the glacier continues to shrink. Volcanic eruptions deposit volcanic tephra on glaciers in Alaska, modifying surface albedo and glacier melt. We mapped the distribution of tephra originating from the eruption of Mt. Spurr in 1992 using aerial photos and satellite imagery on seven glaciers located approximately 180 km east of the volcano in western Chugach Mountains in southcentral Alaska. The glaciers were completely covered with ≥ 500 g m⁻² tephra immediately after the event. Tephra deposits are still visible on all glaciers 26 years after the eruption. Using LandSat 8 surface reflectance bands, we quantified percentages of tephra glacier coverage. Results suggest an increasing tephra extent on five of the seven investigated glaciers over 2013-2018 period explained by firn line retreat. The mean percent increase for all glaciers was 4% with Troublesome Glacier showing greatest increase (~ 7 %) and Finch Glacier showing a slight decrease (~ 1 %). This long- term tephra persistence on glacier surfaces most likely enhanced melt although the precise effect remains unknown.NASA Commercial Remote Sensing Program, NSF OPP-0714045 and NASA NNX11AF41G, U.S. National Park Service's Arctic Network, NSF ARCSS (grant #1418032), National Institute for Water Resources (#2017AK137B), NASA Alaska Space Grant and EPSCoR RID Grant.Chapter 1: General introduction -- Chapter 2: Geodetic mass balance of glaciers in the Central Brooks Range, Alaska, U.S.A., from 1970 to 2001 -- Chapter 3: Modeling the impacts of climate change on mass balance and discharge of Eklutna Glacier, Alaska, 1985-2019 -- Chapter 4: Persistence from 1992 to 2019 of Mt. Spurr tephra deposited on select western Chugach Mountains glacier surfaces -- Chapter 5: Conclusions

Pathways of high-latitude dust in the North Atlantic

The contribution of mineral dust from high-latitude sources has remained an under-examined feature of the global dust cycle. Dust events originating at high latitudes can provide inputs of aeolian sediment to regions lying well outside the subtropical dust belt. Constraining the seasonal variability and preferential pathways of dust from high-latitude sources is important for understanding the potential impacts that the dust may have on wider environmental systems, such as nearby marine or cryospheric domains. This study quantifies dust pathways from two areas exhibiting different emission dynamics in the north and south of Iceland, which is a prominent Northern Hemisphere dust source. The analysis uses air parcel trajectory modelling, and for the first time for high-latitude sources, explicitly links all trajectory simulations to time-specific (meteorological) observations of suspended dust. This approach maximises the potential for trajectories to represent dust, and illustrates that trajectory climatologies not limited to dust can grossly overestimate the potential for dust transport. Preferential pathways emerge that demonstrate the role of Iceland in supplying dust to the Northern Atlantic and sub-Arctic oceans. For dust emitted from northern sources, a dominant route exists to the northeast, into the Norwegian, Greenland and Barents Seas, although there is also potential for delivery to the North Atlantic in summer months. From the southern sources, the primary pathway extends into the North Atlantic, with a high density of trajectories extending as far south as 50ºN, particularly in spring and summer. Common to both southern and northern sources is a pathway to the west-southwest of Iceland into the Denmark Strait and towards Greenland. For trajectories simulated at ≤500 m, the vertical development of dust plumes from Iceland is limited, likely due to the stable air masses of the region suppressing the potential for vertical motion. Trajectories rarely ascend high enough to reach the central portions of the Greenland Ice Sheet. The overall distribution of trajectories suggests that contributions of Icelandic dust are relatively more important for neighbouring marine environments than the cryosphere

The Sixth International Conference on Mars Polar Science and Exploration : September 5-9, 2016, Reykjavik, Iceland

The conference is designed to pull together the current state of Mars polar research from many fields, including geology, atmospheric, and climate sciences.European Geophysical Union Icelandic Meteorological Office International Association of Cryospheric Sciences Lunar and Planetary Institute (LPI) NASA Mars Program Office Planetary Science Institute Southwest Research Institute Université de Nantes University of Iceland in ReykjavikConference Organizing Committee, Isaac Smith, Convener, Southwest Research Institute [and 7 others] ; Science Organizing Committee, Wendy Calvin, University of Nevada [and 13 others

The parent bodies of fine-grained micrometeorites: A petrologic & spectroscopic perspective

Micrometeorites are millimetre-scale cosmic dust grains, derived from asteroids and comets. They represent the largest flux of extraterrestrial material currently falling to Earth, with an estimated contribution of 20,000-60,000 tons per year. In this thesis, the geological history, parent body properties and atmospheric entry of fine-grained micrometeorites are investigated through micro-analysis and spectroscopic techniques. The degree of aqueous alteration within fine-grained micrometeorites was investigated using criteria initially developed for CM chondrites (Chapt.3). This revealed that most particles are intensely altered, with petrologic subtypes <CM2.3. Textural and geochemical evidence of aqueous alteration is seen in the form of hydrated CAIs, hydrated sulfides, pseudomorphic chondrules and complex intergrown and cross-cut assemblages of phyllosilicate, which attest to extended periods in contact with liquid water. Likewise, the apparent overabundance of CM-like matrix and the relative paucity of C2 chondrule material among fine-grained micrometeorites suggest that the parent bodies of fine-grained micrometeorites are predominantly intensely aqueously altered bodies. This study also identified the first evidence for shock deformation in fine-grained micrometeorites (Chapt.6). Weak, pervasive petrofabrics, formed by aligned phyllosilicates and inferred from dehydration crack orientations were observed in the majority of micrometeorites studied (21). This requires relatively low peak pressures (<5GPa) and is most likely achieved by successive low-intensity impact events. The presence of a single micrometeorite containing brittle deformation cataclasis fabrics also provides evidence for brittle deformation shock processing of micrometeorites. The first near-IR spectra of micrometeorites were collected and directly compared against the NIR spectra of young C-type asteroids (Chapt.8). Although these comparisons proved inconclusive, owing to limitations in the quality of the micrometeorite spectra, this study identified the first evidence of hydroxyl-group absorption bands at NIR wavelengths in Veritas family asteroids, suggesting the presence of intact phyllosilicates on their surfaces and thereby adding support to the genetic link between fine-grained micrometeorites and C-type asteroids. Mid-IR spectroscopy revealed how micrometeorite mineralogy evolves during flash heating in the upper atmosphere, demonstrating that solid state recrystallization preserves pre-atmospheric textures, despite major changes in the mineralogy (Chapt.4). Spatially resolved Raman spectroscopy was used to investigate thermal gradients within micrometeorites during atmospheric entry and revealed that most micrometeorite cores preserve low-temperature (<300°C) carbonaceous phases inherited from their parent asteroid (Chapt.5). The development of secondary interconnected porosity was described for the first time, detailing how the growth and expansion of dehydration cracks driven by the out-gassing of volatiles leads to the formation of branching and sinuous channels (Chapt.7). These channels play an important role in the efficient heating of micrometeorite cores resulting in partial melting as scoriaceous micrometeorites are formed. In addition, the development of secondary porosity significantly lowers the mechanical strength of micrometeoroids, promoting their disruption in the atmosphere. Finally, a small-scale study, attempting to retrieve fine-grained micrometeorites preserved in ancient sedimentary rocks was trailed (Chapt.9). This led to the recovery of a new collection of fossil micrometeorites derived from Cretaceous chalk. Although no unmelted micrometeorites were discovered, the preserved cosmic spherules are found to have experienced complete diagenetic alteration, resulting in preserved micro-textures and replaced terrestrial mineralogies. A repeat study at a different time period and location also found cosmic spherules with identical preservation styles, suggesting that diagenetically altered micrometeorites most likely represent the most common form of cosmic dust on Earth.Open Acces

MSATT: Mars Surface and Atmosphere Through Time

The papers published here are based on a workshop entitled "Mars: Past, Present, and Future: Results from the MSATT Program." MSATT (Mars Surface and Atmosphere Through Time) was the last of the Mars data analysis programs and functioned mainly through a series of focused workshops, the final one being held at the Lunar and Planetary Institute in Houston, Texas on November 15-17, 1993. The program began and ended with workshops that brought the entire MSATT community together. Here you will find papers that address the geology, mineralogy, and meteorology of Mars in an effort to assess how the surface and atmosphere of this fascinating planet have evolved over time. Could early Mars have been warmed by a brighter young sun instead of a massive greenhouse effect? Were glaciers and hydrological cycles part of Mars' relatively recent past, or was aeolian activity responsible for the putative glacial features? Do the SNCs come from a single source region, or is more than one site involved? And what really are the properties of Martian soils and what do they tell us about the weathering environment? Clearly, these are difficult questions, but progress toward answers can be found in this issue. Also contained in this issue are a mix of theoretical and observational papers that deal with the general circulation of the current atmosphere, the factors that drive it (dust properties), and the role it plays in controlling the current climate system

Lunar and Planetary Science 37

Includes preface, table of contents, program, abstracts and indexes for the 37th LPSC. This conference included special sessions on: the Bosumtwi Meteorite Impact Crater Drilling Project; the Deep Impact Mission; and the Hayabusa Asteroid Mission.sponsors Lunar and Planetary Institute, NASA Johnson Space Centerprogram committee, Stephen J. Mackwell, co-chair, Eileen K. Stansbery, co-chair ... [and others] ; compiled by Lunar and Planetary Institute.PARTIAL CONTENTS: Constraints on the Huygens Landing Site Topography from the Surface Science Package Acoustic Properties Instrument / M.C. Towner, J. R.C. Garry, H. Svedhem, A. Hagermann, B.C. Clark, R.D. Lorenz, M R. Leese, B. Hathi, and J.C. Zarnecki--Do Hadean Zircons Retain a Record of the Late Heavy Bombardment on Earth? / D. Trail, S.J. Mojzsis, T.M. Harrison, and H.F. Levison--Principal Component Analysis of Geochemical Data at Gusev Crater / E. Tréguier, C. d'Uston, and R. Gellert--Brown and Clear Olivine in Chassignite NWA 2737: Water and Deformation / A.H. Treiman, M. McCanta, M.D. Dyar, C.M. Pieters, T. Hiroi, M.D. Lane, and J.L. Bishop--Two Likely Meteorite-dropping Bolides Recorded by a New High-Res All-Sky CCD Camera / J.M. Trigo-Rodríguez, A.J. Castro-Tirado, M. Jelínek, S. Vitek, J. Llorca, and J. Fabregat

Characterisation of dust sources in Central Asia using remote sensing

Central Asian deserts are a significant source of dust in the middle latitudes, where economic activity and the health of millions of people are affected by dust storms. Detailed knowledge of sources of dust, controls on their activity, seasonality and atmospheric pathways are of crucial importance but to date, these data are limited. This thesis presents a detailed database ofsources ofdust emissions in Central Asia, from western China to the Caspian Sea, obtained by a multi-scale analysis of the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. The multi-scale approach consists of the following steps: 1) MODIS Deep Blue Aerosol Optical Depth (DB AOD) at 10 km resolution, acquired between 2003 and 2014, is used to investigate the spatiotemporal distribution ofdust hotspots. 2) A dust enhancement algorithm was employed to obtain two composite images (Dust Enhancement Product, DEP) per day at 1 km resolution from MODIS Terra/Aqua acquisitions between 2003 and 2012, from which dust point sources (DPS) were detected by visual analysis of dust plumes and recorded in a database together with meteorological variables at each DPS location derived from the ERA-Interim reanalysis dataset. In all, more than 13500 DPS were identified. Using this multi-scale approach we provided a high resolution inventory of dust sources at sub-basin scale for Central Asia. Our analysis revealed several active source regions, the most active of which are the eastern part ofthe Taklmakan desert. An important finding was an increase in dust activity in the newly-formed desert ofthe Aralkum. Several ofthe identified dust source regions were not previously identified (e.g. sources in northern Afghanistan) or were not widely discussed in literature before (e.g. the Pre-Aral region in western Kazakhstan). Investigation of land surface characteristics and meteorological conditions at each source region revealed mechanisms for the formation of dust sources, including rapid desiccation of water bodies (e.g. Aral Sea), deflation of dust from fluvial sources (e.g. the Upper Amudarya region) and post-fire wind erosion (e.g. Pre-Aral and Lake Balkhash basins). Different seasonal patterns of dust emissions were observed as well as inter-annual trends. Comparison of DB AOD and DPS revealed a noticeable spatial bias in the AOD-based methods for detection of dust sources which is attributed to the fact that the highest atmospheric dust loadings are not always observed over the dust point sources