The East Atlantic Oscillation: Mechanism and Impact on the European Climate in Winter

Mikhailova, N.V.; Yurovsky, A.V.

doi:10.22449/1573-160x-2016-4-25-33

Cited by 14 publications

(16 citation statements)

References 10 publications

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“…In the positive EA phase, which is associated with a deep low-pressure system over the Atlantic, warm air masses are prevalent above Europe. Whereas in the negative EA phase there is a high-pressure system over the Atlantic, and this leads to the predominance of cool and dry air masses [79,80].…”

Section: Data and Research Methodsmentioning

confidence: 99%

Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

Graf

Wrzesiński

2019

Water

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The objective of the paper consisted in determining the effect of macroscale types of NAO, AO, EA, EAWR, SCAND, and AMO atmospheric circulation on changes in water temperature in Polish rivers. The study has made use of a broad body of hydrometeorological materials covering daily water temperature values for 96 water gauge stations located on 53 rivers and air temperature values for 43 meteorological stations. Percentage shares of positive and negative coefficients of correlation of annual, seasonal, and monthly circulation type indices with air and river water temperature were determined, demonstrating the character of teleconnection. Determinations were made of water temperature deviations in positive and negative phases of the analyzed indices from average values from the years 1971–2015, and their statistical significance ascertained. Research has shown that relations between the temperature of river waters in Poland and macroscale circulation types are not strong, however they are noticeable, sometimes even statistically significant, and both temporally and spatially diverse. NAO, AO, EA, and AMO indices are characterized by a generally positive correlation with temperature, whereas SCAND and EWAR indices are characterized by a negative correlation. Research showed a varying impact of types of atmospheric circulation, with their effectiveness increasing in the winter season. The strongest impact on temperature was observed for the positive and negative NAO and AO phases, when deviations of water temperature from average values are correspondingly higher (up to 1.0 °C) and lower (by a maximum of 1.5 °C), and also for the positive and negative SCAND phases, when water temperature are correspondingly lower (by a maximum of 0.8 °C) and higher (by 1.2 °C) than average values. The strongest impact on water temperature in summer, mainly in July, was observed for AMO. The results point to the complexity of processes determining the thermal regime of rivers and to the possibility of additional factors—both regional and local—exerting an influence on their temporal and spatial variability.

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Section: Data and Research Methodsmentioning

confidence: 99%

Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

Graf

Wrzesiński

2019

Water

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“…This teleconnection could be attributed to the influence of EA on atmospheric circulation. The winter positive (negative) EA phase indicates a dominating zonal (meridional) circulation (Mikhailova and Yurovsky et al, 2016). Hence, EA can modulate heat and moisture transport.…”

Section: Interannual Variations and Teleconnections 315mentioning

confidence: 99%

Characterizations of Europe's integrated water vapor and assessments of atmospheric reanalyses using more than two decades of ground-based GPS

Peng

Malderen

Yin

et al. 2021

Preprint

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Abstract. Ground-based Global Positioning System (GPS) has been extensively used to retrieve Integrated Water Vapor (IWV) and has been adopted as a unique tool for the assessments of atmospheric reanalyses. In this study, we investigated the multi-temporal-scale variabilities and trends of IWV over Europe by using IWV time series from 108 GPS stations for more than two decades (1994–2018). We then adopted the GPS IWV as a reference to assess six commonly-used atmospheric reanalyses, namely CFSR, ERA5, ERA-Interim, JRA55, MERRA2, and NCEP2. The GPS results show that the diurnal cycles peak within 16:00–24:00 local time with peak-to-peak amplitudes accounting for 2 %–18 % of the daily mean. The diurnal 1-hourly anomalies can be much more intensive with a range of −100 % to 200 %. The annual cycles peak in July and August with maximum values of 17–32 kg m−2. The interannual variations of IWV over Europe are found to be mainly linked to the North Atlantic Oscillation (NAO) and the East Atlantic (EA) patterns. The IWV continues to increase over Europe during the last two decades at 0–0.4 kg m−2 decade−1 in the north and 0.4–1 kg m−2 decade−1 in the south. Regarding the assessments of the reanalyses, the intercomparisons with respect to GPS reveal a general superiority of the newly-released ERA5 IWV product. For instance, ERA5 only has a slight wet bias with a median value of 1 %, whereas the median bias for MERRA2 is 4 %. ERA5, MERRA2, and NCEP2 are the best, second best, and worst performers respectively in modelling the variability of daily IWV time series, with standard deviations of daily IWV differences against GPS by 0.5–1.6, 0.7–2.3, and 1.2–3.0 kg m−2, respectively. Moreover, the daily GPS IWV time series is best correlated with the ERA5 IWV with a median Pearson correlation coefficient of 0.996, whereas the second strongest and weakest median correlations are observed in MERRA2 and NCEP2 with values of 0.991 and 0.971, respectively. Furthermore, the correlations between the IWV trends from the reanalyses and GPS are strongest for ERA5 (0.82), a bit weaker for MERRA2 (0.72), and weakest for NCEP2 (0.52).

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“…Research continues to highlight the importance of the East Atlantic Pattern (EA) in influencing European climate. The EA was first described by Wallace and Gutzler [23] and is cited as the second mode of climate variability in the North Atlantic following the NAO [24,25]. Barnston and Livezey [26] identified a well-defined EA monopole south of Iceland and west of the United Kingdom (approximately 55 • N; 20-35 • W), a definition frequently used in research [24,27,28] and by NOAA in the calculation of their EA teleconnection index [29].…”

Section: Introductionmentioning

confidence: 99%

Monthly Rainfall Signatures of the North Atlantic Oscillation and East Atlantic Pattern in Great Britain

2021

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Atmospheric-oceanic circulations (teleconnections) have an important influence on regional climate. In Great Britain, the North Atlantic Oscillation (NAO) has long been understood as the leading mode of climate variability, and its phase and magnitude have been found to influence regional rainfall in previous research. The East Atlantic Pattern (EA) is also increasingly recognised as being a secondary influence on European climate. In this study we use high resolution gridded rainfall and Standardised Precipitation Index (SPI) time series data for Great Britain to map the monthly rainfall signatures of the NAO and EA over the period January 1950–December 2015. Our analyses show that the influence of the two teleconnections varies in space and time with distinctive monthly signatures observed in both average rainfall/SPI-1 values and incidences of wet/dry extremes. In the winter months the NAO has a strong influence on rainfall and extremes in the north-western regions. Meanwhile, in the southern and central regions stronger EA-rainfall relationships are present. In the summer months opposing positive/negative phases of the NAO and EA result in stronger wet/dry signatures which are more spatially consistent. Our findings suggest that both the NAO and EA have a prominent influence on regional rainfall distribution and volume in Great Britain, which in turn has implications for the use of teleconnection forecasts in water management decision making. We conclude that accounting for both NAO and EA influences will lead to an enhanced understanding of both historic and future spatial distribution of monthly precipitation.

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The East Atlantic Oscillation: Mechanism and Impact on the European Climate in Winter

Cited by 14 publications

References 10 publications

Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

Characterizations of Europe's integrated water vapor and assessments of atmospheric reanalyses using more than two decades of ground-based GPS

Monthly Rainfall Signatures of the North Atlantic Oscillation and East Atlantic Pattern in Great Britain

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