by Sidd Mukherjee
Historically in the United States, atmospheric rivers (AR) have been associated with the West Coast. Now, AR activity is getting more attention on the East Coast.
Atmospheric rivers have been putting serious rainfall melt on Greenland for the last decade, too.
Darker snow surfaces absorb more sunlight and melt quicker. This effect is visible in Greenland. Box et al.,”Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers,” The Cryosphere, v6, pp821 et seq., doi:10.5194/tc-6-821-2012 state: ” Thus, intraseasonal summer albedo variability exceeds 0.50 over parts of the ice sheet where a snow layer ablates by mid-summer, exposing an impurity-rich ice surface …” Prof. Box is now investigating soot from North American wildfires as a factor in the darkening of Greenland.
— from News from the Ice Wars:An Occasional Bulletin
“Furthermore, our investigation of the short- and long-term relationships between moisture transport vents and modeled GrIS surface properties proves that this correspondence between the years of enhanced AR activity and anomalous GrIS mass loss is not a coincidence. Strong AR impacts cause increased melt in all areas of the GrIS and decreased SMB in the ablation zone during summer, and warm seasons with above-average GrIS melt extent are characterized by anomalously strong moisture transport by ARs over Greenland. ARs typically result in SMB gains in the GrIS ablation zone during nonsummer seasons and in the accumulation zone during all seasons. However, the intense summer SMB losses in the ablation zone during years of enhanced moisture transport outweigh the positive AR contributions to SMB in other regions and seasons. The scaling of melt versus snowfall in Figures 9 and 11 shows that the magnitude of mass loss from summer melt in the ablation zone has a much greater upper limit than mass gain from snowfall.”
In this paper see especially Fig. 9.
Then in 2018, Neff publishes again: more on atmospheric rivers causing the full surface melt in greenland in 2012.
— from Atmospheric River Impacts on Greenland Ice Sheet SurfaceMass Balance
“Rainfall at the Greenland ice sheet Summit 14 August 2021, was delivered by an atmospheric river (AR). Extreme surface ablation expanded the all-Greenland bare ice area to near-record-high with snowline climbing up to 788 ± 90 m. Ice sheet wet snow extent reached 46%, a record high for the 15–31 August AMSR data since 2003. Heat-driven firn deflation averaged 0.14 ± 0.05 m at four accumulation area automatic weather stations (AWSs). Energy budget calculations from AWS data indicate that surface heating from rainfall is much smaller than from either the sensible, latent, net-longwave or solar energy fluxes. ”
“Rainfall heat transfer contributed just 2% to the calculated melting at a 2,200 m elevation western ice sheet site (CP1 a.k.a. Crawford Point). Condensation or sensible heat transfer from the warm air mass was a far more powerful heat source. The observed amount of melting delivered by the AR could have happened without rain- fall. Yet, the impacts of rain and meltwater refreeze are considerable provided that percolation delivers the melt below where the heat can be radiated away and that refreeze-at-depth occurs. We found no evidence for the latter condition because the rainfall amount was not extreme and the surface was already melting hours before the rain- fall. Understanding any changes to the frequency and intensity of ARs appears to be a more important research target than the heat content of the liquid precipitation ARs may or may not produce Further, while rainfall that does not percolate and refreeze may not have strong surface thermodynamic impacts, rainfall contribution to the hydraulics of Greenland ice (Doyle et al., 2015) may be more consequential to ablation through ice sheet flow acceleration.”
open access, read all about it. The Watson river discharge described in the paper drains the saddle between north and south domes and is an area that i watch closely for signs of collapse. I suppose this is one.
— from Greenland Ice Sheet Rainfall, Heat and Albedo Feedback Impacts From the Mid-August 2021 Atmospheric River
ALSO SEE:
West Coast Atmospheric Rivers Brouse (2023)
East Coast Atmospheric Rivers Brouse (2023)
The Reign of Violent Rain Brouse and Mukherjee (2023)
The Age of Loss and Damage Brouse (2023)
Climate Change Impacts on Flood Risks and Real Estate Values Sidd Mukherjee and Daniel Brouse (2023)