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  - 
TY  - GEN
A1  - Lara, Mark J.
A1  - Nitze, Ingmar
A1  - Grosse, Guido
A1  - Martin, Philip
A1  - McGuire, A. David
T1  - Reduced arctic tundra productivity linked with landform and climate change interactions
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
N2  - Arctic tundra ecosystems have experienced unprecedented change associated with climate warming over recent decades. Across the Pan-Arctic, vegetation productivity and surface greenness have trended positively over the period of satellite observation. However, since 2011 these trends have slowed considerably, showing signs of browning in many regions. It is unclear what factors are driving this change and which regions/landforms will be most sensitive to future browning. Here we provide evidence linking decadal patterns in arctic greening and browning with regional climate change and local permafrost-driven landscape heterogeneity. We analyzed the spatial variability of decadal-scale trends in surface greenness across the Arctic Coastal Plain of northern Alaska (similar to 60,000 km(2)) using the Landsat archive (1999-2014), in combination with novel 30 m classifications of polygonal tundra and regional watersheds, finding landscape heterogeneity and regional climate change to be the most important factors controlling historical greenness trends. Browning was linked to increased temperature and precipitation, with the exception of young landforms (developed following lake drainage), which will likely continue to green. Spatiotemporal model forecasting suggests carbon uptake potential to be reduced in response to warmer and/or wetter climatic conditions, potentially increasing the net loss of carbon to the atmosphere, at a greater degree than previously expected.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 550 
KW  - winter warming events
KW  - permafrost
KW  - Alaska
KW  - trends
KW  - ice
KW  - CO2
KW  - degradation
KW  - landscapes
KW  - ecosystem
KW  - exchange
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-423132
SN  - 1866-8372
IS  - 550
ER  -