The impact of land use land cover change on LST and its drivers in the arctic and boreal regions
Abstract
In our NASA Arctic Boreal Vulnerability Experiment (ABoVE) project, we focus on the exchange of the carbon and energy between land and atmosphere using remote sensing, modeling, and data assimilation. One of the key controls of the carbon and energy cycles is land use and land cover (LULC). The LULC in the Arctic has been extensively changed over the past few decades due to gradual changes (e.g. shrub encroachment) and more rapid changes such as deforestation caused by wildfire and the expansion of agriculture. Land surface temperature (LST) is directly related to LULC and is a key variable in energy balance and warming/cooling of the Arctic. The main question of this study is how does LULC affect the temporal and spatial variations of LST over the Arctic? We assume that changes in albedo and evapotranspiration are the two main processes through which LULC affects the spatiotemporal changes of LST. Some land use land cover changes are likely to cause large changes in latent and sensible heat. We test the hypotheses that (I) the effect of relatively rare LULC conversions (e.g. forests to wetlands) have the potential to have a greater impact on local energy balance per unit area and (II) the interplay between LST, albedo, and evapotranspiration depends on whether it is located in the energy-limited or water-limited region. In our analysis, we use recently developed high-resolution LULC maps (30m) for the ABoVE core region which includes Alaska and western Canada. To fully uncover the direction and magnitude of the LST-LULC link we use a range of remote sensing and modeled historical datasets (e.g. blue-sky albedo, evapotranspiration) and ground measurements (e.g. EC towers). In our study, we use robust time series and sensitivity analyses. Our preliminary results show both LST and LULC are temporally and spatially dynamic and have undergone substantial changes over time. Sensitivity analyses showed that LST is more sensitive to less common LULC such as wetlands land cover change. The interaction between LST and LULC depends on the season and in some cases they have contrasting directions (i.e. cooling/warming). We also investigated the LST-LULC relationship in different water- or energy-limited regions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB080.0012D
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES