Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.
![Course of the average annual SST (SSTST) from grids [40°N, 50°W] and [40°N, 60°W] and SD13S. Bold solid lines – fitting with a 5th-degree polynomial to empirical courses. SD, sunshine duration; SST, sea surface temperature.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647351904e662f30ba539f38/j_quageo-2023-0023_fig_007.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKCDONMZAN%2F20260306%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260306T014403Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEBAaDGV1LWNlbnRyYWwtMSJGMEQCIB8ZCgA%2BITwkrLg4cnkcH0tVrg7wv5sK6alW9sKaRKxzAiBBSg5OmnF7%2F1jtCsDBMVYEynvzFRAKOE5xlECGOFxzlirGBQjZ%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F8BEAIaDDk2MzEzNDI4OTk0MCIMSh2Fvmj%2BYJ6%2BFiFHKpoFcxj2xw7KvISCwH1sZjbeZrm00ICCP6Ukh2jgPIW0Liw5GZ5l1kxqph5PPXSq%2FYvg6PnJLnN%2BZdjqeAdSvDsQekqaIvGVEgidsjTbdoD3Qac7xVsRfX%2Fkva6c1f1mJLf2TevyZNPjmi4Xm2xareLUjdbR5hhtppSbX%2FRQMWPVDj6L3Q00KxoVWSVGHahflQP5Y1tJC1FdWR6oJ8HzmCNYUVP%2BJJbovvAwHYo8RPeKdRT7HgVqkwhu7ldFezF9LLxyi3a0SDJWicZE%2BdMgj3BJ5EulZodXYi2y3ogTvD0X064DGdaNILr2%2F9zjb4hEv%2B095o9ggYM0HV5Ygh1ymP2%2B%2BaSPPOIUaAhrt00KEmBdrJ%2FKxhKTzbNTrDwITf0TVMY0o04xGx7OZK1CgTxOpw2XkvGF4i3I2gI4ShVJZKPJFO0KqC0Sp0TSweAsE78NaLHzGMMHf74p5WheUWQPLNFIW3jO3Isxmi9q66jxGjVxOpXkGshxVgQrdStFsf1HYc3AJQEfeE2nQudzOjb7uVAgcqzahmsjQWKAxtQRbkzL6w9DejusPhGbTxH71UtCi542QG%2BSD1uA%2BmDvykaxiQD%2FI3SeA9sNZPikPCHfEBCzVgWI8x%2Bk8WoKArWdR8T%2FnVTjZi11bSozZIFQaoBJtjmn6AiEAA9NDvf2RqXB1B9uPCrX24Xi%2FotmhYXlm8BQA0wZQUvViJtCV1MfXvbd1GDkrMKQGe8fBahc8nwqhfJV5avSfUVeoR73%2F8MrVDKtiFoROZroDCOz4YmHkAKTxo%2BRVy%2FmfwJ5i%2FBl4auh%2FhqHz0IytWov2IKe3e2b3De40ODEX6YMNzsi03FkO1MrE7ZIp1q3MwjDbQPj18YrM2VLli4MvwZj7VtiWjanML2lqM0GOrIBP1LbySlujbP5H1A2gMMwwOQT7ZmxjRmm4tl%2B4oybsf2c378wHG%2BZjULMnmT4PpLnDc5B2Cq44GWkuqyURa2pGjJfMxWw%2BJiWgp2ix1pBBhMsxWMF1hPgBlgofobwrYWzcBNmxYXejlDmSou1sXRDnOhq9KFI4YAb9UNzvB1RNW1YlY6ndwwkGMCOaj1i%2FQH4ccph1FLpoOEUug4IesZijcbW8l2js12WkoIZVsT3s60QVA%3D%3D&X-Amz-Signature=80ccb0934873926183ccd7f5170e55ff0e6de0396456c444fdf88594952aae24&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 8.
![Linear correlation coefficients (r) between SD13S and the meridional SST gradient in the North Atlantic between 30 and 60°N to 40°W (average ϕ = 45°N; dSST[40W]) and the geopotential height at h500 at 45°, 50° and 55°N. Significance levels of correlation (p) are marked. Period of analysis 1949–2018. SD, sunshine duration; SST, sea surface temperature.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647351904e662f30ba539f38/j_quageo-2023-0023_fig_008.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKCDONMZAN%2F20260306%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260306T014403Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEBAaDGV1LWNlbnRyYWwtMSJGMEQCIB8ZCgA%2BITwkrLg4cnkcH0tVrg7wv5sK6alW9sKaRKxzAiBBSg5OmnF7%2F1jtCsDBMVYEynvzFRAKOE5xlECGOFxzlirGBQjZ%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F8BEAIaDDk2MzEzNDI4OTk0MCIMSh2Fvmj%2BYJ6%2BFiFHKpoFcxj2xw7KvISCwH1sZjbeZrm00ICCP6Ukh2jgPIW0Liw5GZ5l1kxqph5PPXSq%2FYvg6PnJLnN%2BZdjqeAdSvDsQekqaIvGVEgidsjTbdoD3Qac7xVsRfX%2Fkva6c1f1mJLf2TevyZNPjmi4Xm2xareLUjdbR5hhtppSbX%2FRQMWPVDj6L3Q00KxoVWSVGHahflQP5Y1tJC1FdWR6oJ8HzmCNYUVP%2BJJbovvAwHYo8RPeKdRT7HgVqkwhu7ldFezF9LLxyi3a0SDJWicZE%2BdMgj3BJ5EulZodXYi2y3ogTvD0X064DGdaNILr2%2F9zjb4hEv%2B095o9ggYM0HV5Ygh1ymP2%2B%2BaSPPOIUaAhrt00KEmBdrJ%2FKxhKTzbNTrDwITf0TVMY0o04xGx7OZK1CgTxOpw2XkvGF4i3I2gI4ShVJZKPJFO0KqC0Sp0TSweAsE78NaLHzGMMHf74p5WheUWQPLNFIW3jO3Isxmi9q66jxGjVxOpXkGshxVgQrdStFsf1HYc3AJQEfeE2nQudzOjb7uVAgcqzahmsjQWKAxtQRbkzL6w9DejusPhGbTxH71UtCi542QG%2BSD1uA%2BmDvykaxiQD%2FI3SeA9sNZPikPCHfEBCzVgWI8x%2Bk8WoKArWdR8T%2FnVTjZi11bSozZIFQaoBJtjmn6AiEAA9NDvf2RqXB1B9uPCrX24Xi%2FotmhYXlm8BQA0wZQUvViJtCV1MfXvbd1GDkrMKQGe8fBahc8nwqhfJV5avSfUVeoR73%2F8MrVDKtiFoROZroDCOz4YmHkAKTxo%2BRVy%2FmfwJ5i%2FBl4auh%2FhqHz0IytWov2IKe3e2b3De40ODEX6YMNzsi03FkO1MrE7ZIp1q3MwjDbQPj18YrM2VLli4MvwZj7VtiWjanML2lqM0GOrIBP1LbySlujbP5H1A2gMMwwOQT7ZmxjRmm4tl%2B4oybsf2c378wHG%2BZjULMnmT4PpLnDc5B2Cq44GWkuqyURa2pGjJfMxWw%2BJiWgp2ix1pBBhMsxWMF1hPgBlgofobwrYWzcBNmxYXejlDmSou1sXRDnOhq9KFI4YAb9UNzvB1RNW1YlY6ndwwkGMCOaj1i%2FQH4ccph1FLpoOEUug4IesZijcbW8l2js12WkoIZVsT3s60QVA%3D%3D&X-Amz-Signature=464ed37e13d8359780dc942f4bba9336dfcd0fc4947bace0e1954aa429b6341b&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 9.

Average values of the annual area sunshine duration over Europe (SD13S) and the ranges of their variability in the subsequent North Atlantic Thermohaline Circulation phases_
| North Atlantic Thermohaline Circulation phase | Years | Duration (years) | SD13S (h) | |||
|---|---|---|---|---|---|---|
| Average | Min | Max | Median | |||
| 1 | 1901–1926 | 26 | 1,681.7 | 1,497.0 | 2,050.2 | 1,661.2 |
| 2 | 1927–1963 | 37 | 1,730.1 | 1,514.2 | 1,921.7 | 1,718.1 |
| 3 | 1964–1988 | 25 | 1,575.7 | 1,415.9 | 1,735.2 | 1,582.9 |
| 4 | 1989–2018 | 31 | 1,770.0 | 1,597.1 | 2,032.3 | 1,759.0 |
Stations used in the study_
| No. | Station | Country | Geographical coordinates | Altitude (m a.s.l.) | Number of supplementations of annual mean values | Data source |
|---|---|---|---|---|---|---|
| 1 | Armagh | GB | 54.35°N, 6.65°W | 62 | 0 | Met Office |
| 2 | De Bilt | NL | 52.10°N, 5.18°E | 1 | 1 (1945) | ECAD |
| 3 | Geneva | CH | 46.20°N, 6.15°E | 405 | 0 | ECAD |
| 4 | Basel | CH | 47.53°N, 7.58°E | 316 | 0 | HISTALP |
| 5 | Zurich | CH | 47.38°N, 8.57°E | 555 | 0 | ECAD |
| 6 | Copenhagen | DK | 56.68°N, 12.53°E | 9 | 0 | DMI |
| 7 | Potsdam | DE | 52.38°N, 13.06°E | 81 | 1 (1945) | DWD |
| 8 | Kremsmunster | AT | 48.06°N, 14.13°E | 382 | 0 | HISTALP |
| 9 | Klagenfurt | AT | 46.65°N, 14.32°E | 459 | 0 | HISTALP |
| 10 | Zagreb | HR | 45.82°N, 15.97°E | 157 | 1 (1921) | HISTALP |
| 11 | Vienna | AT | 48.25°N, 16.36°E | 209 | 0 | HISTALP |
| 12 | Wroclaw | PL | 51.10°N, 16.90°E | 120 | 0 | Brys (2013), Marsz et al. (2021) |
| 13 | Krakow | PL | 50.07°N, 19.97°E | 206 | 0 | IGiGP UJ |
Characteristics of the DG3L index in the North Atlantic Thermohaline Circulation phases occurring in the years 1901–2018_
| North Atlantic Thermohaline Circulation Phases | Years | Duration (years) | DG3L index | |||
|---|---|---|---|---|---|---|
| Average | Min | Max | STD | |||
| 1 | 1901–1926 | 26 | −0.846 | −1.921 | 0.682 | 0.605 |
| 2 | 1927–1963 | 37 | 0.844 | −0.116 | 1.879 | 0.563 |
| 3 | 1964–1988 | 25 | −0.782 | −1.836 | −0.073 | 0.472 |
| 4 | 1989–2018 | 31 | 1.851 | 0.299 | 4.836 | 1.226 |