Abstract:
Amplified warming in the Arctic has likely increased the rate of landscape change and
disturbances in northern high latitude regions. Remote sensing provides a valuable tool
for assessing the spatial and temporal patterns associated with arctic landscape dynamics
over annual, decadal, and centennial time scales. In this dissertation, I focused on remote
sensing studies associated with four primary components of arctic landscape change and
disturbance: (1) permafrost coastline erosion, (2) thermokarst lake dynamics, (3) tundra
fires, and (4) using repeat airborne LiDAR for the measurement of vertical deformation
in an arctic coastal lowland landscape. By combining observations from several high
resolution satellite images for a 9 km segment of the Beaufort Sea Coast between 2008
and 2012, I demonstrated that the report of heightened erosion at the beginning of the
2000s was equaled or exceeded in every year except 2010 and that the mean annual
erosion rate was tightly coupled to the number of open water days and the number of
storms. By combining historical aerial photographs from the 1950s and 1980s with
recent high-resolution satellite imagery from the mid-2000s, I assessed the expansion and
drainage of thermokarst lakes on the northern Seward Peninsula. I found that more than
half of the lakes in the study area were expanding as a result of permafrost degradation
along their margins but that the rate of expansion was fairly consistent (0.35 and 0.39
m/yr) between the 1950s and 1980s and 1980s and mid-2000s, respectively. However, it
appeared that in a number of instances that expansion of lakes led to the lateral drainage
and that over the 55-year study period the total lake area decreased by 24%. While these studies highlight the utility of quantifying disturbance during the remotely sensed image
archive period (~1950s to present) they are inherently limited temporally. Thus, I also
demonstrated techniques in which field studies and remote sensing data could be
combined to extend the identification of landscape disturbance events that occurred prior
to the remote sensing archive. I identified two large regions indicative of past
disturbance caused by tundra fires on the North Slope of Alaska, which doubled the
delineated area of tundra fire disturbance on the North Slope over the last 100 to 130
years. I conclude the dissertation by demonstrating the utility of repeat airborne light
detection and ranging (LiDAR) data for arctic landscape change studies, in particular
vertical surface deformation, and provide momentum for going forward with this
emerging technology for remote sensing of arctic landscape dynamics. The
quantification of arctic landscape dynamics during and prior to the remote sensing
archive is important for ongoing monitoring and modeling efforts of the positive and
negative feedbacks associated with amplified Arctic climate change.
