Abstract
This study examines the long-term fluctuations in the Northern Hemisphere (NH) and global atmospheric circulation, teleconnections, including blocking, and surface temperature over the period 1899–2018. The teleconnection and blocking data were available from the mid-20th century. The classification of the global atmospheric circulation was developed from an early subjective categorization of atmospheric circulation conditions for the NH that considered the number, location, and amplitude of waves on the jet stream for frequently occurring circulation patterns. This work updated earlier studies that identified three circulation epochs based on the predominance of one of four different flow types that were grouped primarily based on whether the flow was zonal or meridional. This work noted a significant correlation between the early 21st century flow change toward the occurrence of more meridional flows and the increase in the occurrence of blocking as well as changes in the teleconnection indexes. The early 21st century was associated with a distinct change in the Northern Hemisphere flow entropy as measured using Information or Shannon Entropy, a change that was shown to be statistically significant. Additionally, this demonstrated that this quantity has utility as a dynamic diagnostic tool in atmospheric science. Finally, a comparison of these flow regimes to the 20th and 21st century variations in surface temperature were considered here. The global average annual surface temperature variations correlated strongly to fluctuations in the predominant atmospheric circulation type.
Highlights
For the analysis of global of hemispheric atmospheric flow regimes, many teleconnection or blocking indexes have been developed and are currently used (e.g., [1,2]) both operationally and in research
The circulation types are classified using surface maps and 500 hPa height fields which are assimilated daily using the general circulation model developed by the Russian Academy of Science Institute for Computational Mathematics and plotted on a 2.0◦ by 2.5◦
The occurrence frequency of Northern Hemisphere (NH) flow regimes from 1899 to 2018 was examined using the daily DKV46 NH flow classification scheme which is archived at the Institute of Geography (Russian Academy of Sciences) in Moscow and available via the website [36]
Summary
For the analysis of global of hemispheric atmospheric flow regimes, many teleconnection or blocking indexes have been developed and are currently used (e.g., [1,2]) both operationally and in research. Among the first of these was a classification system developed for the categorization of extratropical atmospheric circulation patterns in the NH published in [5] (hereafter called DKV46). This system classifies NH flows based on whether the NH flow is more zonal or meridional, as well as the number and geographical position of waves along the polar front or jet stream [1,6]. Recent research [1] showed the correlation of certain ECMs to NH teleconnections such as the Arctic
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
