The summer 2012 Greenland heat wave: in situ and remote sensing observations of water vapour isotopic composition during an atmospheric river event†

peer reviewed During July 7-12, 2012, extreme moist and warm conditions occurred over Greenland, leading to widespread surface melt. To investigate the physical processes during the atmospheric moisture transport of this event, we study the water vapour isotopic composition using surface in situ obs...

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Bibliographic Details
Published in:Journal of Geophysical Research: Atmospheres
Main Authors: Bonne, JL, Steen-Larsen, HC, Risi, C., Werner, M., Sodemann, H., Lacour, J.L., Fettweis, Xavier, Cesana, G., Delmotte, M., Cattani, O., Vallelonga, P., Kjær, H.E., Clerbaux, C., Sveinbjörnsdóttirffilmark, A.E., Masson-Delmotte, V.
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2015
Subjects:
Physical
chemical
mathematical & earth Sciences
Earth sciences & physical geography
Physique
chimie
mathématiques & sciences de la terre
Sciences de la terre & géographie physique
Greenland
Ice Sheet
Ivittuut
North Atlantic
Online Access:https://orbi.uliege.be/handle/2268/178827
https://doi.org/10.1002/2014JD022602
Description
Summary:peer reviewed During July 7-12, 2012, extreme moist and warm conditions occurred over Greenland, leading to widespread surface melt. To investigate the physical processes during the atmospheric moisture transport of this event, we study the water vapour isotopic composition using surface in situ observations in Bermuda Island, South Greenland coast (Ivittuut) and Northwest Greenland ice sheet (NEEM), as well as remote sensing observations (IASI instrument on-board MetOp-A), depicting propagation of similar surface and mid-tropospheric humidity and δD signals. Simulations using Lagrangian moisture source diagnostic and water tagging in a regional model showed that Greenland was affected by an atmospheric river transporting moisture from the western subtropical North Atlantic Ocean, which is coherent with observations of snow pit impurities deposited at NEEM. At Ivittuut, surface air temperature, humidity and δD increases are observed. At NEEM, similar temperature increase is associated with a large and long-lasting ~100 δD enrichment and ~15 deuterium excess decrease, thereby reaching Ivittuut level. We assess the simulation of this event in two isotope-enabled atmospheric general circulation models (LMDz-iso and ECHAM5-wiso). LMDz-iso correctly captures the timing of propagation for this event identified in IASI data but depict too gradual variations when compared to surface data. Both models reproduce the surface meteorological and isotopic values during the event but underestimate the background deuterium excess at NEEM. Cloud liquid water content parametrization in LMDz-iso poorly impacts the vapour isotopic composition. Our data demonstrate that during this atmospheric river event the deuterium excess signal is conserved from the moisture source to Northwest Greenland.

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