Multi-sensor approach for high space and time resolution land surface
temperature
Abstract
Surface-atmosphere fluxes and their drivers vary across space and time.
A growing area of interest is in downscaling, localizing, and/or
resolving sub-grid scale energy, water, and carbon fluxes and drivers.
Existing downscaling methods require inputs of land surface properties
at relatively high spatial (e.g., sub-kilometer) and temporal (e.g.,
hourly) resolutions, but many observed land surface drivers are not
available at these resolutions. We evaluate an approach to overcome this
challenge for land surface temperature (LST), a World Meteorological
Organization Essential Climate Variable and a key driver for surface
heat fluxes. The Chequamegon Heterogenous Ecosystem Energy-balance Study
Enabled by a High-density Extensive Array of Detectors (CHEESEHEAD19)
field experiment provided a scalable testbed. We downscaled LST from
satellites (GOES-16 and ECOSTRESS) with further refinement using
airborne hyperspectral imagery. Temporally and spatially downscaled LST
compared well to observations from a network of 20 micrometeorological
towers and airborne in addition to Landsat-based LST retrieval and
drone-based LST observed at one tower site. The downscaled 50-meter
hourly LST showed good relationships with tower
(r2=0.79, precision=3.5 K) and airborne
(r2=0.75, precision=2.4 K) observations over space and
time, with precision lower over wetlands and lakes, and some improvement
for capturing spatio-temporal variation compared to geostationary
satellite. Further downscaling to 10 m using hyperspectral imagery
resolved hotspots and cool spots on the landscape detected in drone LST,
with significant improvement in precision by 1.3 K. These results
demonstrate a simple pathway for multi-sensor retrieval of high space
and time resolution LST.