Abstract
Abstract. The CryoSat-2 radar altimeter and ICESat-2 laser altimeter can
provide complementary measurements of the freeboard and thickness of Arctic
sea ice. However, both sensors face significant challenges for accurately
measuring the ice freeboard when the sea ice is melting in summer months.
Here, we used crossover points between CryoSat-2 and ICESat-2 to compare
elevation retrievals over summer sea ice between 2018–2021. We focused on
the electromagnetic (EM) bias documented in CryoSat-2 measurements,
associated with surface melt ponds over summer sea ice which cause the radar
altimeter to underestimate elevation. The laser altimeter of ICESat-2 is not
susceptible to this bias but has other biases associated with melt ponds.
So, we compared the elevation difference and reflectance statistics between
the two satellites. We found that CryoSat-2 underestimated elevation
compared to ICESat-2 by a median difference of 2.4 cm and by a median
absolute deviation of 5.3 cm, while the differences between individual
ICESat-2 beams and CryoSat-2 ranged between 1–3.5 cm. Spatial and temporal
patterns of the bias were compared to surface roughness information derived
from the ICESat-2 elevation data, the ICESat-2 photon rate (surface
reflectivity), the CryoSat-2 backscatter, and the melt pond fraction derived from
Sentinel-3 Ocean and Land Color Instrument (OLCI) data. We found good agreement between theoretical
predictions of the CryoSat-2 EM melt pond bias and our new observations;
however, at typical roughness <0.1 m the experimentally measured
bias was larger (5–10 cm) compared to biases resulting from the theoretical
simulations (0–5 cm). This intercomparison will be valuable for interpreting
and improving the summer sea ice freeboard retrievals from both altimeters.
Subject
Earth-Surface Processes,Water Science and Technology
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献