Snow surface albedo changes in the last two decades across the South
America (11°N-76°S): Some highlights revealed by satellite observations
Abstract
Snow is among the most reflective of natural surfaces on Earth and in
its reflectance, also known as snow surface albedo (SSA), a small SSA
decrease can increase its absorption of solar energy. Also, climate
models indicate that the reduction of SSA contributes to global warming
and near-worldwide melting of cryosphere. The snowpack through South
America (SA) is mainly associated to the Andes mountain range, which
geologically extends 9000 km approx. from the tropical region (11°N) to
the Antarctandes (76°S) in the Antarctic. There, snow is an important
source of fresh water for more than 80 million people who live in the 9
countries where this mountain passes. In this study we have analyzed the
SSA trend. For that, in accordance with the division proposed by
Dussaillant et al. (2019), we have divided the study area into 8 zones:
Inner Tropics (11°N-5°S), Outer Tropics (5°S-18°S), Desert Andes (18°
S-31°S), Central Andes (31°S-37°S), North Patagonia (37°S-46°S), South
Patagonia (46°S-54°S), Fuegian Andes (54°S- 56°S), and Antarctandes
(63°S- 76°S). We used daily data of SSA available from the Moderate
Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Terra and
Aqua satellites for the last 20 years (Mar 2000 to Feb 2020). The
results show that the greatest negative inter and intra-annual trends
(i.e. is a decrease in SSA) during the last 20 years were observed in
the Central Andes (April, -5.76%; p <0.001), North Patagonia
(Nov, -2.33%; p <0.05) and Fuegian Andes (Oct, -1.73%; p
<0.05). While the greatest positive variations were detected
in Antarctandes (May, 4.76%; p <0.001), Fuegian Andes (Dec,
4%; p <0.05), and Outer Tropics (Dec, 1.67%; p
<0.01). The highest SSA decrease observed in the Central Andes
is consistent with previous studies carried out by the authors that have
shown an association between light-absorbing particles with SSA decrease
in various basins there. Our results could serve to better understand
the radiative forcing changes generated in the SA cryosphere and its
effects on climate change.