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Title: Critical Mechanisms for the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996

A warming Arctic climate is undergoing significant e 21 nvironmental change, most evidenced by the reduction of Arctic sea-ice extent during the summer. In this study, we examine two extreme anomalies of September sea-ice extent in 2007 and 1996, and investigate the impacts of cloud fraction (CF), atmospheric precipitable water vapor (PWV), downwelling longwave flux (DLF), surface air temperature (SAT), pressure and winds on the sea-ice variation in 2007 and 1996 using both satellite-derived sea-ice products and MERRA reanalysis. The area of the Laptev, East Siberian and West Chukchi seas (70-90oN, 90-180oE) has experienced the largest variation in sea-ice extent from year-to-year and defined here as the Area Of Focus (AOF). The record low September sea-ice extent in 2007 was associated with positive anomalies 30 of CF, PWV, DLF, and SAT over the AOF. Persistent anti-cyclone positioned over the Beaufort Sea coupled with low pressure over Eurasia induced easterly zonal and southerly meridional winds. In contrast, negative CF, PWV, DLF and SAT anomalies, as well as opposite wind patterns to those in 2007, characterized the 1996 high September sea-ice extent. Through this study, we hypothesize the following positive feedbacks of clouds, water vapor, radiation and atmospheric variables on the sea-icemore » retreat during the summer 2007. The record low sea-ice extent during the summer 2007 is initially triggered by the atmospheric circulation anomaly. The southerly winds across the Chukchi and East Siberian seas transport warm, moist air from the north Pacific, which is not only enhancing sea-ice melt across the AOF, but also increasing clouds. The positive cloud feedback results in higher SAT and more sea-ice melt. Therefore, 40 more water vapor could be evaporated from open seas and higher SAT to form more clouds, which will enhance positive cloud feedback. This enhanced positive cloud feedback will then further increase SAT and accelerate the sea-ice retreat during the summer 2007.« less
 [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Beijing Normal Univ. (China); Univ. of North Dakota, Grand Forks, ND (United States)
  2. Univ. of North Dakota, Grand Forks, ND (United States)
  3. Georgia Inst. of Technology, Atlanta, GA (United States)
  4. Univ. of Alaska, Fairbanks, AK (United States)
  5. NASA Langley Research Center, Hampton, VA (United States)
  6. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN ‎0930-7575; KP1703020
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Climate Dynamics, 43(1-2):53-70; Journal Volume: 43; Journal Issue: 1-2
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES Sea-Ice Extent Anomalies; Warming Arctic Climate; Arctic Sea-ice; September