Anupma Prakash
University of Alaska Anchorage, Geology and Geophysics, Faculty Member
Tidewater glaciers calve icebergs into the marine environment which serve as pupping, molting, and resting habitat for some of the largest seasonal aggregations of harbor seals (Phoca vitulina richardii) in the world. Although they are... more
Tidewater glaciers calve icebergs into the marine environment which serve as pupping, molting, and resting habitat for some of the largest seasonal aggregations of harbor seals (Phoca vitulina richardii) in the world. Although they are naturally dynamic, advancing and retreating in response to local climatic and fjord conditions, most tidewater glaciers around the world are thinning and retreating. Climate change models predict continued loss of land-based ice with unknown impacts to organisms such as harbor seals that rely on glacier ice as habitat for critical life history events. To understand the impacts of changing ice availability on harbor seals, we quantified seasonal and annual changes in ice habitat in Johns Hopkins Inlet, a tidewater glacier fjord in Glacier Bay National Park in southeastern Alaska. We conducted systematic aerial photographic surveys (n = 55) of seals and ice during the pupping (June; n = 30) and molting (August; n = 25) periods from 2007 to 2014. Object-...
Research Interests: Oceanography, Habitat, Tidewater Glacier, Trade Offs, Ice, and 4 moreFjord, Glacier, Phoca, and Tidewater
ABSTRACT Data from current and planned satellite missions can play an important role in providing synoptic atmospheric, terrestrial and oceanic environmental data from space. These data promotes multidisciplinary research in the... more
ABSTRACT Data from current and planned satellite missions can play an important role in providing synoptic atmospheric, terrestrial and oceanic environmental data from space. These data promotes multidisciplinary research in the circumpolar regions and can be instrumental in furthering our understanding of the Earth as a System. The International Polar Year in 2007 (IPY-4) presents unprecedented opportunities for integrated circumpolar research and for education outreach to a wide audience ranging from preschoolers through high end researchers, defined by NASA as the ''pipeline''. We foresee a world-wide participation which improve science competence and citizen awareness of the importance of the Polar Regions. Opportunities for integrating native knowledge of the indigenous residents of the Arctic is an essential component of IPY programs. Acquisition of reliable ground truth data in support of remote sensing of geophysical and geochemical variables are essential, especially with broad long-term coverage in the Polar Regions. In the United States NASA has developed a strategy for long-term monitoring of some key parameters needed to bring us closer to the answers we need regarding climate change and its relation to social systems. This technology consists of a group of six satellites that can make a suite of earth observations referred to as the ''A-Train''. Data from this group of polar orbiting satellites, as well as from the Orbital Carbon Observatory (OCO), and older Quikscat and new Seawinds radar missions, provide focus for an education program based not only on the acquisition of polar data but also on how these data correlate with global observations. This work presents strategies and recommendations for streamlining an effective educational outreach program in the IPY-4. It presents a concept of disseminating data, models and research results to a variety of audience and integrating several traditional aspects in building a strong educational component to IPY-4.
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Methane hydrate (crystalline solid in which water molecules form an ice-like framework that trap gas molecules) is an attractive energy resource because of its high energy density of any other naturally occurring form of methane, as well... more
Methane hydrate (crystalline solid in which water molecules form an ice-like framework that trap gas molecules) is an attractive energy resource because of its high energy density of any other naturally occurring form of methane, as well as its relatively close proximity to the Earth's surface and seafloor (Pellenbarg 2000). Hydrate distribution on the Alaska North Slope (ANS), Prudhoe Bay region, is thought to be controlled by the availability of migrated thermogenic hydrocarbon gas from depth, via the Eileen and other fault zones. Migration along the Eileen Fault Zone (8,000 ft below the surface) intersects the pressure/temperature stability field of gas hydrates which would allow excess gases (mainly methane) from gas hydrate formation continue migrating toward the surface. A gas charged pingo, with comparable gas composition to gas hydrates found at depth, is evidence that some of the trace methane gases at depth continue migrating to the surface (Collett pers. comm.). Using...
Research Interests: Geology, Remote Sensing, Gas Hydrate, Permafrost, Natural Gas, and 3 moreStable Isotope, Methane, and Bay
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The computation of turbulent fluxes of heat, momentum, and greenhouse gases requires measurements taken at high sampling frequencies. An important step in this process involves the detection and removal of sudden, short-lived variations... more
The computation of turbulent fluxes of heat, momentum, and greenhouse gases requires measurements taken at high sampling frequencies. An important step in this process involves the detection and removal of sudden, short-lived variations that do not represent physical processes and that contaminate the data (i.e., spikes). The objective of this study is to assess the performance of several noteworthy despiking methodologies in order to provide a benchmark assessment and to provide a recommendation that is most applicable to high-frequency micrometeorological data in terms of efficiency and simplicity. The performance of a statistical time window–based algorithm widely used in micrometeorology is compared to three other methodologies (phase space, wavelet based, and median filter). These algorithms are first applied to a synthetic signal (a clean reference version and then one with spikes) in order to assess general performance. Afterward, testing is done on a time series of actual CO...
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Research Interests: Geography, Geology, Bathymetry, Placer Mining, Shore, and 3 moreBay, Submarine Pipeline, and Placer Deposit
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Abstract During an explosive volcanic eruption, accurately determining the height of a volcanic plume or cloud is essential to accurately forecast its motion because volcanic ash transport and dispersion models require the initial plume... more
Abstract During an explosive volcanic eruption, accurately determining the height of a volcanic plume or cloud is essential to accurately forecast its motion because volcanic ash transport and dispersion models require the initial plume height as an input parameter. The direct use of satellite infrared temperatures for height determination, one of the most commonly employed methods at the Alaska Volcano Observatory, often does not yield unique solutions for height. This result is documented here for the 2009 eruption of ...
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An airborne geophysical survey was conducted by the State of Alaska in the summer of 1999 in the Salcha River-Pogo area to support exploration for economically viable mineral deposits. We processed and analyzed a subset of the airborne... more
An airborne geophysical survey was conducted by the State of Alaska in the summer of 1999 in the Salcha River-Pogo area to support exploration for economically viable mineral deposits. We processed and analyzed a subset of the airborne geophysical data, ...
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The scientific data collected by research programs funded by the government belongs to the public. As such it is the responsibility of the scientific and technical communities to make scientific data accessible and usable by the... more
The scientific data collected by research programs funded by the government belongs to the public. As such it is the responsibility of the scientific and technical communities to make scientific data accessible and usable by the educational community. However, much geoscience data are difficult for educators and students to find and use. They are generally described by metadata that are
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ABSTRACT In the Alaskan Arctic foothills, hydrology can be quantified at multiple scales from water movement at the soil pore level, flow between tussocks and hummocks, to basin level measurements ranging from a few square kilometers to... more
ABSTRACT In the Alaskan Arctic foothills, hydrology can be quantified at multiple scales from water movement at the soil pore level, flow between tussocks and hummocks, to basin level measurements ranging from a few square kilometers to hundreds. Regardless of scale, evapotranspiration is the largest unknown component of the hydrological cycle, the most difficult to accurately measure and highly spatially and temporally variable. Understanding the local, regional and global linkages of climate change in terms of hydrology depends on developing a better understanding of evapotranspiration since it significantly alters future scenario predictions. This study was based on transects which bisected drainage networks of water tracks in the Imnavait, Toolik and Upper Kuparuk basins in the Toolik Lake long-term ecological research area. Each 200 m transect had between five and seven 2 m2 plots where vegetation percent cover, soil morphology and depth to the active layer was documented. Each plot was also quantified using visible, near IR and thermal imagery. This data was used to generate a value of the normalized difference vegetation index (NDVI). According to previous research, field measurements can be used to generate an estimate of leaf area index (LAI). This was compared to the thermal data collected, since the relationship between LAI and temperature is the main input to the two-source energy balance model which can estimate evapotranspiration rates. Confounding factors, such as the potential effect of moss its associated moisture content, will be explored over all the different spectrums of the collected imagery.
Research Interests: Environmental Science, Remote Sensing, Climate Change, Arctic, Evapotranspiration, and 11 moreEnergy Balance, Data Collection, Leaf Area Index, Spectrum, Moisture Content, Thermal Imagery, Long Term Ecological Research, Temporal Variability, Active Layer, Normalized Difference Vegetation Index, and Field Measurement
The Akutan geothermal system, which is a part of Alaska's Aleutian volcanic arc, has several known thermal springs and a known fumarole field. It is reported to be one of the few high-grade geothermal resources in Alaska with a... more
The Akutan geothermal system, which is a part of Alaska's Aleutian volcanic arc, has several known thermal springs and a known fumarole field. It is reported to be one of the few high-grade geothermal resources in Alaska with a potential for further development as a geothermal energy resource. However, there is paucity of data and limited understanding and characterization of
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ABSTRACT A combined use of remote sensing techniques, modeling and in-situ measurements is a pragmatic approach to study arctic hydrology, given the vastness, complexity, and logistical challenges posed by most arctic watersheds. Remote... more
ABSTRACT A combined use of remote sensing techniques, modeling and in-situ measurements is a pragmatic approach to study arctic hydrology, given the vastness, complexity, and logistical challenges posed by most arctic watersheds. Remote sensing techniques can provide tools to assess the geospatial variations that form the integrated response of a river system and therefore provide important details to study climate change effects on the remote arctic environment. The proposed study tests the applicability of remote sensing and modeling techniques to map, monitor and compare river temperatures and river break-up in the coastal and foothill sections of the Kuparak River, which is an intensely studied watershed. We co-registered about hundred synthetic aperture radar (SAR) images from RADARSAT-1, ERS-1 and ERS-2 satellites, acquired during the months of May through July for a period between 1999 and 2010. Co-registration involved a Fast Fourier Transform (FFT) match of amplitude images. The offsets were then applied to the radiometrically corrected SAR images, converted to dB values, to generate an image stack. We applied a mask to extract pixels representing only the river, and used an adaptive threshold to delineate open water from frozen areas. The variation in river break-up can be bracketed by defining open vs. frozen river conditions. Summer river surface water temperatures will be simulated through the well-established HEC-RAS hydrologic software package and validated with field measurements. The three-pronged approach of using remote sensing, modeling and field measurements demonstrated in this study can be adapted to work for other watersheds across the Arctic.
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Recently Virtual Globes, for example Google Earth, have become a popular tool for visualizing scientific data. Stretching the capabilities of these tools, beyond the limits for which they were initially designed, we at the University of... more
Recently Virtual Globes, for example Google Earth, have become a popular tool for visualizing scientific data. Stretching the capabilities of these tools, beyond the limits for which they were initially designed, we at the University of Alaska have improved our research and decision support capabilities. For volcanic ash plume visualization, we have transformed modeled results into their true four dimensional form incorporating spatio-temporal components.
Reflectance spectroscopic, methylene blue, and X-ray diffraction (XRD) analyses have been applied to ~400 m of drill cuttings and core from an exploration well at Pilgrim Hot Springs, Alaska with the aim of rapidly characterizing the... more
Reflectance spectroscopic, methylene blue, and X-ray diffraction (XRD) analyses have been applied to ~400 m of drill cuttings and core from an exploration well at Pilgrim Hot Springs, Alaska with the aim of rapidly characterizing the extent and style of lowtemperature hydrothermal alteration as well as determining paths of geothermal fluid-flow. Sample reflectance spectra indicate a mineral assemblage comprised predominantly of montmorillonite, illite, chlorite, and kaolinite with depth-related variations in mineral assemblages, specifically in core section, related to changing alteration intensity. The observations from reflectance spectroscopy show good agreement with the results of methylene blue analyses concerning the distribution of smectite within the cuttings and core samples. The results of XRD for a limited set of the drill cuttings show reasonable agreement with the outcomes of reflectance spectroscopy and methylene blue analyses. The results of this study reveal a histor...
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Numerical modeling has been effectively used in this study to assess the potential and production sustainability of the Pilgrim Hot Springs geothermal system in Alaska. The TOUGH 2 software package was used to generate numerical... more
Numerical modeling has been effectively used in this study to assess the potential and production sustainability of the Pilgrim Hot Springs geothermal system in Alaska. The TOUGH 2 software package was used to generate numerical simulation and stimulation models. The fluid and heat flow in the geothermal system were reconstructed using geological and geophysical constraints with model simulation parameters optimized via a history matching of subsurface temperature profiles. The reservoir simulation model was used to predict the heat loss from the system for both conductive and convective heat fluxes. This served as the basis for the development of reservoir stimulation model encompassing a production scenario with a plausible configuration of production and injection wells. This reservoir stimulation model was used to estimate the thermal energy from the production wells. The estimated energy potential of the Pilgrim Hot Springs geothermal system from the reservoir simulation model ...
Recent Arctic warming has led to changes in the hydrological cycle. Circum-Arctic and circumboreal ecosystems are showing evidence of “greening” and “browning” due to temperature warming leading to shrub encroachment, tree mortality and... more
Recent Arctic warming has led to changes in the hydrological cycle. Circum-Arctic and circumboreal ecosystems are showing evidence of “greening” and “browning” due to temperature warming leading to shrub encroachment, tree mortality and deciduousness. Increases in latent heat flux from increased evapotranspiration rates associated with deciduous-dominated ecosystems may be significant, because deciduous vegetation has extremely high-water use and water storage capacity compared to coniferous and herbaceous plant species. Thus, the impact of vegetation change in boreal ecosystems on regional surface energy balance is a significant knowledge gap that must be addressed to better understand observed trends in water use/availability and tree mortality. To this end, output from a two-source energy balance model (TSEB) with modifications for high latitude boreal ecosystems was evaluated using flux tower measurements and Terra/Aqua MODIS remote sensing data collected over the two largest bo...
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Six DEMs over a 10-year period were used to estimate flood-related sedimentation in the Japanese Creek drainage located in Seward, Alaska. We analyze two existing LiDAR DEMs and one GNSS-derived DEM along with three additional DEMs that... more
Six DEMs over a 10-year period were used to estimate flood-related sedimentation in the Japanese Creek drainage located in Seward, Alaska. We analyze two existing LiDAR DEMs and one GNSS-derived DEM along with three additional DEMs that we generated using differential Global Navigation Satellite System (dGNSS) and Structure from Motion (SfM) techniques. Uncertainties in each DEM were accounted for, and a DEMs of Difference (DoD) technique was used to quantify the amount and pattern of sediment introduced, redistributed, or exiting the system. Through correlating the changes in sediment budget with rainfall data and flood events, the study demonstrates that the major flood events in 2006 and 2012—the 7th and 5th highest precipitation events on record—resulted in an increased sedimentation in the drainage as a whole. At a minimum the 2006 and 2012 events increased the sediment in the lower reaches by 70,100 and 53,900 cubic meters, respectively. The study shows that the DoD method and...
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The Colville is an Arctic river in the Alaska North Slope. The residents of Nuiqsut rely heavily on the Colville for their subsistence needs. Increased erosion has been reported on the Colville, especially along bluffs, which shaped the... more
The Colville is an Arctic river in the Alaska North Slope. The residents of Nuiqsut rely heavily on the Colville for their subsistence needs. Increased erosion has been reported on the Colville, especially along bluffs, which shaped the goals of this study: to use remote sensing techniques to map and quantify erosion rates and the volume of land loss at selected bluff sites along the main channel of the Colville, and to assess the suitability of automated methods of regional erosion monitoring. We used orthomosaics from high resolution aerial photos acquired in 1955 and 1979/1982, as well as high resolution WorldView-2 images from 2015 to quantify long-term erosion rates and the cubic volume of erosion. We found that, at the selected sites, erosion rates averaged 1 to 3.5 m per year. The erosion rate remained the same at one site and increased from 1955 to 2015 at two of the four sites. We estimated the volume of land loss to be in the magnitude of 166,000 m3 to 2.5 million m3 at ou...
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Land surface temperature (LST) is one of the sources of input data for modeling land surface processes. The Landsat satellite series is the only operational mission with more than 30 years of archived thermal infrared imagery from which... more
Land surface temperature (LST) is one of the sources of input data for modeling land surface processes. The Landsat satellite series is the only operational mission with more than 30 years of archived thermal infrared imagery from which we can retrieve LST. Unfortunately, stray light artifacts were observed in Landsat-8 TIRS data, mostly affecting Band 11, currently making the split-window technique impractical for retrieving surface temperature without requiring atmospheric data. In this study, a single-channel methodology to retrieve surface temperature from Landsat TM and ETM+ was improved to retrieve LST from Landsat-8 TIRS Band 10 using near-surface air temperature (Ta) and integrated atmospheric column water vapor (w) as input data. This improved methodology was parameterized and successfully evaluated with simulated data from a global and robust radiosonde database and validated with in situ data from four flux tower sites under different types of vegetation and snow cover in...
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Augustine Volcano (located in the Cook Inlet of South Central Alaska at 59.4oand 153.4oW) erupted in January 2006 and released, among other things, water vapor, radiation heat, and aerosols into the atmosphere. To determine the potential... more
Augustine Volcano (located in the Cook Inlet of South Central Alaska at 59.4oand 153.4oW) erupted in January 2006 and released, among other things, water vapor, radiation heat, and aerosols into the atmosphere. To determine the potential impact of volcanic emissions and ashfall on local weather, 16 simulations assuming artificial emission and ashfall scenarios were performed with the Weather Research and Forecasting model for 24 consecutive days starting the day before the first eruption. These simulations include (1) the control simulation without consideration of any volcanic perturbation, (2) four simulations with simplified scenarios for each individual volcanic factor [radiative heat from the caldera, water vapor, cloud condensation nuclei (CCN) and/or ice nuclei (IN) aerosols, and albedo change due to ashfall], and (3) 11 simulations containing all possible combinations of these factors. These 11 simulations serve to examine interactions among impacts of the different perturba...
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Ground-based surveys of three coal fires and airborne surveys of two of the fires were conducted near Sheridan, Wyoming. The fires occur in natural outcrops and in abandoned mines, all containing Paleocene-age subbituminous coals. Diffuse... more
Ground-based surveys of three coal fires and airborne surveys of two of the fires were conducted near Sheridan, Wyoming. The fires occur in natural outcrops and in abandoned mines, all containing Paleocene-age subbituminous coals. Diffuse (carbon dioxide (CO(2)) only) and vent (CO(2), carbon monoxide (CO), methane, hydrogen sulfide (H(2)S), and elemental mercury) emission estimates were made for each of the fires. Additionally, gas samples were collected for volatile organic compound (VOC) analysis and showed a large range in variation between vents. The fires produce locally dangerous levels of CO, CO(2), H(2)S, and benzene, among other gases. At one fire in an abandoned coal mine, trends in gas and tar composition followed a change in topography. Total CO(2) fluxes for the fires from airborne, ground-based, and rate of fire advancement estimates ranged from 0.9 to 780mg/s/m(2) and are comparable to other coal fires worldwide. Samples of tar and coal-fire minerals collected from th...