http://www.igsoc.org/journal/56/198/j09j079.pdf
Comparison of satellite, thermochron and air temperatures at
Summit, Greenland, during the winter of 2008/09
Lora S. KOENIG, Dorothy K. HALL
Cryospheric Sciences Branch, NASA Goddard Space Flight Center, Code 614.1, Greenbelt, Maryland 20771, USA
E-mail:
lora.s.koenig@nasa.gov
ABSTRACT. Current trends show a rise in Arctic surface and air temperatures, including over the
Greenland ice sheet where rising temperatures will contribute to increased sea-level rise through
increased melt. We aim to establish the uncertainties in using satellite-derived surface temperature for
measuring Arctic surface temperature, as satellite data are increasingly being used to assess temperature
trends. To accomplish this, satellite-derived surface temperature, or land-surface temperature (LST),
must be validated and limitations of the satellite data must be assessed quantitatively. During the 2008/
09 boreal winter at Summit, Greenland, we employed data from standard US National Oceanic and
Atmospheric Administration (NOAA) air-temperature instruments, button-sized temperature sensors
called thermochrons and the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite
instrument to (1) assess the accuracy and utility of thermochrons in an ice-sheet environment and (2)
compare MODIS-derived LSTs with thermochron-derived surface and air temperatures. The thermochron-
derived air temperatures were very accurate, within 0.10.38C of the NOAA-derived air
temperature, but thermochron-derived surface temperatures were 38C higher than MODIS-derived
LSTs. Though surface temperature is largely determined by air temperature, these variables can differ
significantly. Furthermore, we show that the winter-time mean air temperature, adjusted to surface
temperature, was 118C higher than the winter-time mean MODIS-derived LST. This marked difference
occurs largely because satellite-derived LSTs cannot be measured through cloud cover, so caution must
be exercised in using time series of satellite LST data to study seasonal temperature trends.