Anomalies of air temperature at the earth's surface and their connection with processes in the stratosphere

Currently, special attention is paid to the study of the interaction processes between the troposphere and the stratosphere.

Based on the data on the maximum daily air temperature, presented by the archives of the ECA & D project [3], for the cold season from December to March, for the time period 1951-2018, normalized temperature anomalies were calculated for each month for 46 meteorological stations. Long-term positive air temperature anomalies in the European territory of the Russian Federation were studied. Significant warming was considered to be periods when the normalized positive anomaly of the maximum air temperature was above the 90th percentile for at least 5 days in a row [1].

The analysis showed that for the entire period from December to March 1951-2018. According to spatial distribution at the studied stations, the following months were abnormally warm: December 2006, December 2008, March 2007 and February 1990.

It was revealed that the longest heat anomalies were observed in January 2007 (19 days) at Kaliningrad station (from 01 to 19 January 2007) and Trubchevsk station (from 05 to 23 January 2007); in December 2006 (17 days) at 7 stations simultaneously: St. Petersburg, Moscow, Vytegra, Tikhvin, Rybinsk, Staritsa and Maksatikha (from 01 December to 17 December 2006); and in February 2002 (17 days) at Pudino station (from 09 to 25 February 2002). 

The analysis showed that the distribution of anomalies in the winter months is dominated by west-east transfer. In rare cases, warming spread from south to east and north (usually not reaching 600 N) and from north, northwest to southeast. Another situation was observed in March - in most cases, warming began in the northwest of the European territory of Russia with a gradual capture of southern stations. And only in two cases did heat anomalies spread from east to west.

One of the factors of dynamic interaction between circulation in the lower stratosphere and air temperature anomalies at the earth's surface in winter is the Northern Annular Mode (NAM) [2]. 

To analyze the relationship between heat anomalies and processes in the stratosphere, the correlation between positive air temperature anomalies at the underlying surface and the Northern Annular Mode (NAM) index [4]. 

The conducted correlation analysis showed that the maximum relationship between the Northern Annular Mode index and positive air temperature anomalies is clearly visible in the northwest of the European territory of Russia - periods of anomalous warming coincide with pronounced positive values ​​of the NAM index.

1. Alekseeva E.G., Aniskina O.G. Analysis of long-term heat anomalies in winter // Collection of abstracts of the International scientific and practical conference "Modern problems of hydrometeorology and environmental monitoring in the CIS". - St. Petersburg: Russian State Hydrometeorological University. - 2020. - P. 107 -108.

2. Alekseeva O.G., Aniskina O.G. Influence of atmospheric circulation on extreme air temperature in the North-West of Russia // Proceedings of the International Conference "Climate risks and space weather" - Irkutsk: Irkutsk State University. - 2021. - P. 238 - 242.

3. URL: https://www.ecad.eu/ (date of access 18.02.2023)

4. URL: http://ljp.gcess.cn/dct/page/65571 (date of access 18.02.2023)