Changes in the Dynamics of the Northern Hemisphere Atmospheric Circulation and the Relationship to Surface Temperature in the 20th and 21st Centuries

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.

Evaluation of Historical CMIP5 GCM Simulation Results Based on Detected Atmospheric Teleconnections

“…Usage of the diversity index and the loess-method enabled the evaluation of GCMs with respect to the intensity of various teleconnections without fading their signals. The application of information entropy to evaluate atmospheric models and to examine atmospheric teleconnections is gaining popularity recently [77,78]. The usage of the loess-method as a GCM evaluation tool with respect to atmospheric teleconnections is a novel method to the authors' knowledge.…”

The influence of atmospheric circulation on the occurrence of dry and wet periods in Central Poland in 1954–2018

“…The occurrence of the so-called circulation epochs (e.g. Sidorenkov and Orlov 2008;Degirmendžić and Kożuchowski 2018;Kononova and Lupo 2020) is one of the natural causes of the observed climate change. They are associated with increased or weaker appearance of certain types of atmospheric circulation, which favours the incidence of deficient or excessive precipitation.…”

Comparative analysis of frequency of dry winds occurrence in Ukraine in the mid-20th century and at the beginning of the 21st century

“…Зміни атмосферної циркуляції, що відбулися наприкінці ХХ − початку ХХІ століття демонструють, що навесні та влітку відзначається збільшення числа днів з меридіональною південною групою циркуляції, та як наслідок панування середземноморських циклонів, і значне зменшення, з середини 30-х років ХХ ст. до першого десятиліття ХХІ ст., числа днів з зональною групою циркуляції, за типізацією Дзердзеєвського [13]. Сприятливі умови для утворення суховіїв при проходженні середземноморських циклонів пов'язані з посиленням швидкостей вітру і виносом в їх передній частині теплого субтропічного повітря.…”