The role of blocking circulation and emerging open water feedbacks on Greenland cold‐season air temperature variability over the last century. (5th November 2020)

• Record Type: Journal Article
• Authors: Ballinger, Thomas J.; Hanna, Edward; Hall, Richard J.; Carr, J. Rachel; Brasher, Saber; Osterberg, Erich C.; Cappelen, John; Tedesco, Marco; Ding, Qinghua; Mernild, Sebastian H.
• Is Part Of: International journal of climatology. Volume 41(2021)Supplement 1
• Page Start: E2778
• Page End: E2800
• Publication Date: 2020-11-05
• Subjects: air temperatures -- Greenland -- Greenland Blocking Index -- sea ice; Climatology -- Periodicals; Climat -- Périodiques; Climatologie -- Périodiques; 551.605
• DOI: 10.1002/joc.6879
• Languages: English
• ISSNs: 0899-8418

Abstract

Abstract: Substantial marine, terrestrial, and atmospheric changes have occurred over the Greenland region during the last century. Several studies have documented record‐levels of Greenland Ice Sheet (GrIS) summer melt extent 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 model‐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 r 2 ~ 50%) can be explained by the seasonally‐contemporaneous combination of the Greenland Blocking Index (GBI) and the North Atlantic Oscillation (NAO; hereafter the combination of GBI and NAO is termed GBI). Lagged and concomitant regional sea‐ice concentration (SIC) and the Atlantic Multidecadal Oscillation (AMO) seasonal indices account for small amounts of residual air temperature variance ( r 2 < ~10%) relative to the GBI. The correlations between GBI and cold‐season temperatures are predominantly positive and statistically‐significant through time, while regional 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. Abstract : Our study presents a long‐term analysis of Greenland autumn and winter air temperature (T2m) variability and examines the influence of local and remote oceanic and atmospheric forcing of T2m variations through time. We show that in both seasons, Greenland blocking is consistently linked with T2m, while relationships between Baffin Bay ice cover and T2m have been strengthening over the last half century. These results suggest that large‐scale atmospheric circulation largely controls T2m, but may increasingly modulate local sea ice‐atmosphere interactions.