TY  - JOUR
A1  - Creighton, Andrea L.
A1  - Parsekian, Andrew D.
A1  - Angelopoulos, Michael
A1  - Jones, Benjamin M.
A1  - Bondurant, A.
A1  - Engram, M.
A1  - Lenz, Josefine
A1  - Overduin, Pier Paul
A1  - Grosse, Guido
A1  - Babcock, E.
A1  - Arp, Christopher D.
T1  - Transient Electromagnetic Surveys for the Determination of Talik Depth and Geometry Beneath Thermokarst Lakes
JF  - Journal of geophysical research : Solid earth
N2  - Thermokarst lakes are prevalent in Arctic coastal lowland regions and sublake permafrost degradation and talik development contributes to greenhouse gas emissions by tapping the large permafrost carbon pool. Whereas lateral thermokarst lake expansion is readily apparent through remote sensing and shoreline measurements, sublake thawed sediment conditions and talik growth are difficult to measure. Here we combine transient electromagnetic surveys with thermal modeling, backed up by measured permafrost properties and radiocarbon ages, to reveal closed-talik geometry associated with a thermokarst lake in continuous permafrost. To improve access to talik geometry data, we conducted surveys along three transient electromagnetic transects perpendicular to lakeshores with different decadal-scale expansion rates of 0.16, 0.38, and 0.58m/year. We modeled thermal development of the talik using boundary conditions based on field data from the lake, surrounding permafrost and a borehole, independent of the transient electromagnetics. A talik depth of 91m was determined from analysis of the transient electromagnetic surveys. Using a lake initiation age of 1400years before present and available subsurface properties the results from thermal modeling of the lake center arrived at a best estimate talk depth of 80m, which is on the same order of magnitude as the results from the transient electromagnetic survey. Our approach has provided a noninvasive estimate of talik geometry suitable for comparable settings throughout circum-Arctic coastal lowland regions.
KW  - geophysics
KW  - permafrost
KW  - thermokarst
KW  - electromagnetic
KW  - lake
Y1  - 2018
U6  - https://doi.org/10.1029/2018JB016121
SN  - 2169-9313
SN  - 2169-9356
VL  - 123
IS  - 11
SP  - 9310
EP  - 9323
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Nitze, Ingmar
A1  - Grosse, Guido
A1  - Jones, Benjamin M.
A1  - Arp, Christopher D.
A1  - Ulrich, Mathias
A1  - Fedorov, Alexander
A1  - Veremeeva, Alexandra
T1  - Landsat-Based Trend Analysis of Lake Dynamics across Northern Permafrost Regions
JF  - Remote sensing
N2  - Lakes are a ubiquitous landscape feature in northern permafrost regions. They have a strong impact on carbon, energy and water fluxes and can be quite responsive to climate change. The monitoring of lake change in northern high latitudes, at a sufficiently accurate spatial and temporal resolution, is crucial for understanding the underlying processes driving lake change. To date, lake change studies in permafrost regions were based on a variety of different sources, image acquisition periods and single snapshots, and localized analysis, which hinders the comparison of different regions. Here, we present a methodology based on machine-learning based classification of robust trends of multi-spectral indices of Landsat data (TM, ETM+, OLI) and object-based lake detection, to analyze and compare the individual, local and regional lake dynamics of four different study sites (Alaska North Slope, Western Alaska, Central Yakutia, Kolyma Lowland) in the northern permafrost zone from 1999 to 2014. Regional patterns of lake area change on the Alaska North Slope (-0.69%), Western Alaska (-2.82%), and Kolyma Lowland (-0.51%) largely include increases due to thermokarst lake expansion, but more dominant lake area losses due to catastrophic lake drainage events. In contrast, Central Yakutia showed a remarkable increase in lake area of 48.48%, likely resulting from warmer and wetter climate conditions over the latter half of the study period. Within all study regions, variability in lake dynamics was associated with differences in permafrost characteristics, landscape position (i.e., upland vs. lowland), and surface geology. With the global availability of Landsat data and a consistent methodology for processing the input data derived from robust trends of multi-spectral indices, we demonstrate a transferability, scalability and consistency of lake change analysis within the northern permafrost region.
KW  - lake dynamics
KW  - lake change
KW  - permafrost region
KW  - Landsat
KW  - Alaska
KW  - Siberia
KW  - thermokarst
KW  - trend analysis
KW  - machine-learning
Y1  - 2017
U6  - https://doi.org/10.3390/rs9070640
SN  - 2072-4292
VL  - 9
PB  - MDPI
CY  - Basel
ER  -