Land Surface Temperature Mapping and Analysis of Moss Banks on the
Western Antarctic Peninsula using a multi-sensor UAV
Abstract
Climate change is impacting polar regions at an accelerated rate,
causing rapid changes in land cover and biodiversity. One case is the
“greening up” of the Western Antarctic Peninsula (WAP), the result of
receding glacial fronts exposing substrate for plants and soil
development, together with higher temperatures and potential increases
in cloud-free conditions conducive to plant growth. The 2019/2020
austral summer was the warmest on record for the WAP, yet the controls
on land surface temperature (LST) here are not well understood. We
investigated the relationships between land cover type, solar radiation,
and LST for several vegetated coastal outcrops (0.3 to 0.5 ha)
distributed from 64 to 65°S along the WAP. Remote sensing data was
collected in February/March 2020 using a consumer-grade unmanned aerial
vehicle (UAV), additionally equipped with near-IR and thermal-IR
sensors. Digital surface models produced from the UAV imagery were used
to calculate surface solar radiation. NDVI was used to identify four
land cover classes: healthy vegetation, unhealthy vegetation, loose
substrate, bedrock. Thermal-IR data provided sub-decimeter LST mapping.
LST ranges varied depending on atmospheric conditions. A site surveyed
under cloud-free conditions and air temperature of 6.6°C showed a 37.2°C
range in LST, while a nearby site surveyed the next day under overcast
conditions and air temperature of 2°C showed a 10.4°C range in LST.
Vegetation at these two sites reached maximum temperatures of 27°C and
11.6°C, respectively. We found little within-site difference in either
mean or range of LST among the land cover classes. Using linear
regression, solar radiation explained less than 50% of the observed
LST. Healthy vegetation showed the strongest relationship between solar
radiation and LST. It was determined that LST in the WAP was strongly
affected by factors other than solar radiation, implying latent heat
effects. As the abundance of healthy vegetation increases in these
areas, LST may show a stronger relationship with solar radiation, thus
effecting local feedbacks to warming. This study presents the first
application of UAV-derived thermal-IR data for the analysis of LST
controls in Antarctica, highlighting the capability of UAV as a data
collection platform for use in remote and relatively data-poor
environments.