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SUMMARY:Atmosphere-Snow interactions through the lens of stable water isot
 opes\; the impact for ice core records
DTSTART:20240404T160000
DTEND:20240404T170000
DTSTAMP:20260429T172315Z
UID:a6ea54a8ff7a24adb7915e7488246af69b6f1e3f7b917d72898d35ba
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Sonja Wahl\nPresented by Dr Sonja Wahl\, Postdoc researche
 r\, Geophysical Institute\, University of Bergen & Bjerknes Centre for Cl
 imate Research\, Bergen\, Norway\n\nCryospheric processes and interaction
 s between the cryosphere and other Earth system components are complex\, h
 ost important climate feedbacks and are often difficult to measure. Yet th
 eir understanding is crucial for predicting the evolution of the cryospher
 e in a changing climate. Stable water isotopes are natural tracers of phas
 e change processes within the hydrological cycle. The variability of the i
 ndividual and combined isotope species offer a way to constrain environmen
 tal climatic conditions during phase change processes. Thus\, they are a p
 rime tool to investigate air-snow interactions\, which are at the core of 
 one of the most uncertain but eminently important climate feedbacks. In po
 lar settings these phase change processes are predominantly vapor depositi
 on and snow or ice sublimation. However\, the principle of isotopic fracti
 onation during sublimation has been controversially discussed and the usef
 ulness of tracing stable water isotopes in cryospheric processes is thus d
 ebated.\nHere we demonstrate through field observations and laboratory exp
 eriments that air-snow humidity exchange leaves an isotopic fingerprint in
  the snow isotopic composition. We present in- situ data from the Greenlan
 d Ice Sheet and new results from cold-laboratory wind tunnel experiments. 
 The measurements comprise isotopic signatures of snow\, vapor and of the h
 umidity flux itself. We show that snow sublimation is a fractionating proc
 ess and outline how this information can be used to improve cryospheric pr
 ocess understanding. Specifically\, we investigate the process of drifting
  and blowing snow by observing the evolution of both vapor and snow isotop
 ic composition during cold-laboratory wind tunnel experiments. We document
  the existence of hitherto unobserved airborne snow metamorphism\; a proce
 ss observable on the macro-scale only through the lens of stable water iso
 topes. Based on the combined observations of in-situ surface humidity flux
 es and wind tunnel experiments we discuss a physical explanation for the o
 bserved isotopic fractionation during snow sublimation. These insights and
  the data set will be the basis for determining the fractionation factors
  associated with airborne snow metamorphism. Our results have important im
 plications for the interpretation of stable water isotope signals from sno
 w and ice cores and challenge the translation of the second-order paramete
 r d-excess signal in polar regions as moisture source signal.\n\nThis semi
 nar will be held in hybrid mode. \n 
LOCATION:ALP 1 109 https://plan.epfl.ch/?room==ALP%201%20109 https://uib.z
 oom.us/j/65765123860?pwd=TzNuYys4VWVCbk5JNVFKRE1udDFZUT09
STATUS:CONFIRMED
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