A13C-0352
Summer Climate Responses to Atmospheric Teleconnections and Greenland Ice Mass Variations in the Last Four Decades from the MERRA-2 Reanalysis

Monday, 14 December 2015
Poster Hall (Moscone South)
Young-Kwon Lim1, Siegfried D Schubert2, Sophie Nowicki1, Jae Lee1, Andrea Molod1, Richard I Cullather3, Bin Zhao1 and Isabella Velicogna4, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)Global Modeling and Assimilation Office, Greenbelt, MD, United States, (3)University of Maryland College Park, College Park, MD, United States, (4)University of California Irvine, Irvine, CA, United States
Abstract:
The relationship between some of the leading atmospheric teleconnections and Greenland temperature, precipitation, and surface mass balance (SMB) are investigated for the last 36 summers (1979-2014) based on MERRA-2 reanalyses and GPCP precipitation. The results show that the negative phase of both the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), associated with warm and dry conditions, lead to SMB decreases by 0-1 months. Furthermore, the positive phase of the East Atlantic (EA) pattern often lags the negative NAO, reflecting a dynamical linkage between these modes that acts to further enhance the warm and dry condition over Greenland, leading to a favorable environment for enhanced ice mass loss. The most significant relationships between these teleconnections and temperature (precipitation) occur predominantly over southwestern (southern) Greenland.

A combination of the NAO, AO, and EA (referred to as the NAE) explains the Greenland summer climate variation somewhat better than the NAO alone (corr.= 0.66 versus 0.60). The NAE, however, fails to account for the recent cool summers of 2009, 2011, as well as those of the early 1990’s (following the eruption of Pinatubo). During 2009 and 2011, westward shifted (compared to what occurred during the severe ice mass loss cases of 2010 and 2012) local high pressure blocking produced colder northerly flow over Greenland inhibiting ice mass melting, despite the occurrence of a strong negative NAO. In general, anomalous anticyclonic or cyclonic circulation cells over Greenland produce advective temperature changes that primarily impact western Greenland, while changes in net surface radiative fluxes account for both western and eastern Greenland temperature changes. The NAE faithfully captures the observed SMB and runoff variability such that smaller (larger) SMB and larger (smaller) runoff than average occurs in severe (modest) ice loss summers.

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