The role of blocking circulation and emerging open water feedbacks on Greenland cold-season air temperature variability over the last century

• Published in: International Journal of Climatology
• Main Authors: Ballinger, T.J., Hanna, E., Hall, R., Carr, R., Brasher, S., Osterberg, E., Cappelen, J., Tedesco, M., Ding, Q., Mernild, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: F860 Climatology; Greenland; Pacific; Baffin; glacier; Ice Sheet; North Atlantic; North Atlantic oscillation; Sea ice
• Online Access: https://eprints.lincoln.ac.uk/id/eprint/42549/; https://eprints.lincoln.ac.uk/id/eprint/42549/1/__network.uni_staff_S1_cjoyner_Saved%20outputs_joc.6879.pdf; https://doi.org/10.1002/joc.6879

Substantial marine, terrestrial, and atmospheric changes have occurred over the Greenland region during the last century. For example, several efforts have documented record-levels of Greenland Ice Sheet (GrIS) summer melt extent and intensity during the 2000s and 2010s, but relatively little work has been carried out to assess regional climatic changes in other seasons. Here, we focus on the less studied cold-season (i.e., autumn and winter) climate, tracing the long-term (1873–2013) variability of Greenland’s air temperatures through analyses of coastal observations and model8 derived outlet glacier series and their linkages with North Atlantic sea ice, sea surface temperature (SST), and atmospheric circulation indices. Through a statistical framework, large amounts of west and south Greenland temperature variance (up to r2~50%) can be explained by the seasonally contemporaneous combination of the Greenland Blocking Index (GBI) and the North Atlantic Oscillation (NAO; hereafter GBI). Lagged and concomitant Baffin sea-ice concentration (SIC) and the Atlantic Multidecadal Oscillation (AMO) seasonal indices account for small amounts of air temperature residual variance (r2<~10%) relative to the GBI. The correlations between GBI and autumn and winter air temperatures are predominantly positive and statistically-significant through time, while Baffin SIC conditions emerge as a significant covariate from the mid-20th century through the conclusion of the study period. The inclusion of the cold-season Pacific Decadal Oscillation (PDO) in multivariate analyses bolsters the air temperature variance explained by the North Atlantic regional predictors, suggesting the remote, background climate state is important to long-term Greenland temperature variability. These findings imply that large-scale tropospheric circulation has a strong control on surface temperature over Greenland through dynamic and thermodynamic impacts and stress the importance of understanding the evolving two-way linkages between the North Atlantic marine and atmospheric environment in order to more accurately predict Greenland seasonal climate variability and change through the 21st century.