Blowing snow sublimation and transport over Antarctica from 11 years of CALIPSO observations

Abstract

Abstract. Blowing snow processes commonly occur over the earth's ice sheets when the 10 m wind speed exceeds a threshold value. These processes play a key role in the sublimation and redistribution of snow thereby influencing the surface mass balance. Prior field studies and modeling results have shown the importance of blowing snow sublimation and transport on the surface mass budget and hydrological cycle of high-latitude regions. For the first time, we present continent-wide estimates of blowing snow sublimation and transport over Antarctica for the period 2006-2016 based on direct observation of blowing snow events. We use an improved version of the blowing snow detection algorithm developed for previous work that uses atmospheric backscatter measurements obtained from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite. The blowing snow events identified by CALIPSO and meteorological fields from MERRA-2 are used to compute the blowing snow sublimation and transport rates. Our results show that maximum sublimation occurs along and slightly inland of the coastline. This is contrary to the observed maximum blowing snow frequency which occurs over the interior. The associated temperature and moisture reanalysis fields likely contribute to the spatial distribution of the maximum sublimation values. However, the spatial pattern of the sublimation rate over Antarctica is consistent with modeling studies and precipitation estimates. Overall, our results show that the 2006-2016 Antarctica average integrated blowing snow sublimation is about 393 ± 196 Gt yr −1 , which is considerably larger than previous model-derived estimates. We find maximum blowing snow transport amount of 5 Mt km −1 yr −1 over parts of East Antarctica and estimate that the average snow transport from continent to ocean is about 3.7 Gt yr −1 . These continent-wide estimates are the first of their kind and can be used to help model and constrain the surface mass budget over Antarctica.

Deglacial evolution of regional Antarctic climate and Southern Ocean conditions in transient climate simulations

“…Accumulation from the ERA-Interim Analysis defined as precipitation minus sublimation has been shown to 165 closely match airborne radar observations over the Thwaites Glacier in West Antarctica (Medley et al, 2013), however, we note that the contribution of wind-transported snow may also be locally significant in some areas, particularly in coastal areas dominated by katabatic winds (Palm et al, 2017). As such, we emphasize caution in interpreting accumulation changes in the climate models in areas of strong wind speed, but in terms of overall ice sheet mass balance, wind-transported snow is generally considered to be a relatively minor component (Palm 170 et al, 2017).…”

“…The records include alkenone-derived SST from Core MD03-2611 off the coast of South Australia (Calvo et al, 150 2007), Core TN057-21-PC2 in the South Atlantic (Sachs et al, 2001), and the Ocean Drilling Program (ODP) core of site 1233 off the coast of Southern Chile (Kaiser et al, 2005), and Mg/Ca-derived SST from Core MD97-2120 from Chatham Rise (Pahnke et al, 2003). Additional details on the proxy data are presented in Here, we define accumulation as precipitation minus surface evaporation/sublimation (P -E).…”

Toward a Satellite‐Derived Climatology of Blowing Snow Over Antarctica

“…Because the vertical resolution of CALIOP data is only 30 m, it is not possible to reliably detect blowing snow layers less than about 30 m in thickness. Thus, drifting snow is not included in the results shown here, nor are blowing snow layers of thickness less than about 30 m. A description of the algorithm used to detect blowing snow from CALIOP attenuated backscatter data is given in Palm et al (; and further refined in Palm et al, ) and will only be briefly discussed here. Examples of typical wintertime blowing snow layers that are detected from CALIOP data are shown in Figure .…”

“…The typical magnitude of attenuated backscatter coefficient seen within the layer ranges from about 5 × 10 −6 to 1 × 10 −4 m −1 ·sr −1 with occasional values as high as 2–3 × 10 −4 m −1 ·sr −1 . One additional feature of the blowing snow attenuated backscatter profile is that the signal strength generally decreases with height; this feature has been used for identifying the blowing snow layer in our algorithms (Palm et al, , ).…”

“…Thus, a 25% (blue) or 50% (green) increase in frequency in these regions is more substantial. We also looked for trends in mass transport using the data presented in Figure 8 of Palm et al (2017) but found no areas of statistically significant trend.…”