The impact of El Niño–southern oscillation upon weather regimes over Europe and the North Atlantic during boreal winter

Moron, Vincent; Plaut, G.

doi:10.1002/joc.890

Cited by 83 publications

(88 citation statements)

References 42 publications

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“…During the 6-day window, the SLPAs are negative south of 55-60°N and positive from Greenland to Scandinavia (Figure 3), consistently similar to the 'Greenland above' weather regime (Moron and Plaut, 2003) or to a negative North Atlantic oscillation (NAO) phase (Jones et al, 1997). The Azores high is weakened and shifted southwestward and the 'Greenland above' weather regime gives rise to a southward shift of the North Atlantic storm track (Rogers, 1997).…”

Section: Daily Analysismentioning

confidence: 75%

Relationship between sea-level pressure and sea-level height in the Camargue (French Mediterranean coast)

Moron

Ullmann

2005

Int. J. Climatol.

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A statistical study of daily maximum sea-level height at one station (Grau de la Dent) in the Camargue (Rhône delta, French Mediterranean coast) and daily sea-level pressure (SLP) at 12 h UTC over the eastern North Atlantic is used to identify the meteorological conditions associated with sea-level variations in the Camargue for the winters 1974-75 to 2000-01. Mean SLP composites during and 5 days before major surge events (defined as those with a daily maximum sea-level height >80 cm) suggest the dominant influence of storms, moving northwest to southeast across the North Atlantic and strengthening as they approach the Bay of Biscay. During such storms, strong onshore winds may persist for up to 4-5 days. These winds tend to strengthen from 3 days to 1 day before the surge events. The mean October-March correlation between daily maximum sea-level height in the Camargue and SLP averaged over the Bay of Biscay (10°W-0°, 40-50°N) is strong (r = 0.69). A methodology is developed for assessing the low-frequency SLP variability impact on sea-level height in the Camargue. A cross-validated linear regression is used to hindcast the interannual and intraseasonal variability of the monthly 75th and 90th percentiles of the daily maximum sea-level height from the monthly mean SLP over the Bay of Biscay. The linear correlation between the cross-validated hindcast and observed time series is 0.83 (0.77) for the 75th (90th) percentile on the 1974-75 to 2000-01 period. The mean bias error, reflecting systematic errors in predicting the monthly percentiles, is close to zero.

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Section: Daily Analysismentioning

confidence: 75%

Relationship between sea-level pressure and sea-level height in the Camargue (French Mediterranean coast)

Moron

Ullmann

2005

Int. J. Climatol.

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“…The NCAR SLP standardized anomalies of the 93.9% of days without missing values are weighted by the cosine of latitude and compressed onto the 11 leading empirical orthogonal functions (EOFs) that account for 90% of the total variance. The standard k-means algorithm (Diday and Simon, 1976) is applied to the 11 principal components to extract five clusters, in accordance with previous studies (Vautard, 1990;Michelangeli et al, 1995;Plaut and Simonnet, 2002;Moron and Plaut, 2003). 200 cluster analyses were performed with random seeds and the classifiability index (Michelangeli et al, 1995;Plaut and Simonnet, 2002) that measures the average similarity within the 200 sets of clusters is used to select the best partition.…”

Section: Weather Classificationmentioning

confidence: 99%

“…Weather regime 5 (Figure 4(f)) is characterized by a weak ridge over the mid-eastern Atlantic, followed by a trough stretching from Scandinavia to Eastern Mediterranean sea. This weather regime is called the 'Atlantic Ridge' (AR) regime in reference to previous studies (Michelangeli et al, 1995;Plaut and Simonnet, 2002;Moron and Plaut;2003).…”

Section: Weather Regimesmentioning

confidence: 99%

“…The weather regimes are defined as persistent and recurrent large-scale flow patterns that appear repeatedly at fixed geographical locations, and thus organize the behaviour of synoptic systems that affect local-scale weather during several days or consecutive weeks. The five-cluster solution emphasizing well-known weather regimes already observed in this area (Vautard, 1990;Michelangeli et al, 1995;Plaut and Simonnet, 2002;Moron and Plaut, 2003) is chosen (Section 3b). The mean sea surge heights during each weather regime is analysed, as well as the frequency of weather regimes for different sea surge levels (Sections 3c, 3d).…”

Section: Introductionmentioning

confidence: 99%

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Weather regimes and sea surge variations over the Gulf of Lions (French Mediterranean coast) during the 20th century

Ullmann

Moron

2007

Intl Journal of Climatology

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Hourly sea surge variations observed at three tide-gauge stations (Grau-de-la-Dent(GD) located in the Rhône Delta, Sète(SE), and Port-Vendres(PV)) around the Gulf of Lions are strongly correlated during the wintertime period (October to March) of 1986-1995. Relationships between the early morning (6 a.m. UTC) sea surge observed at Grau-de-la-Dent station and five weather regimes -Zonal (ZO), East-Atlantic (EA), Greenland Above (GA), Blocking (BL), and Atlantic Ridge (AR) -over the northeast Atlantic and Europe (40°W-40°E, 30°-70°N) are analysed during the wintertime period of 1905-2002. More than 75% of sea surges ≥ 40 cm occur during both of the weather regimes associated with a negative North Atlantic Oscillation(NAO) phase (41.2 and 34% during BL and GA weather regimes, respectively), ahead of low pressure travelling usually southeastward, on a stormtrack shifted south of 55°N. The relationships between monthly/seasonal frequency of weather regime and 75th percentile of sea surge at GD tend to strengthen during the 20th century: for example, correlation between seasonal frequencies of GA and 75th percentile of sea surge increases from 0.07 (not significant) in 1905-40 to 0.83 (signifiicant at the one-sided 99% level) in 1974-2002.

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“…ENSO, the dominant pattern of interannual tropical climate variability, has significant influences around the globe (e.g., Trenberth et al 1998). Many observational and modeling studies have indicated that the surface signal of El Niño (La Niña) events in late winter in the North Atlantic-European region appears as a projection onto a negative (positive) phase of the NAO, and the negative (positive) NAO phase occurs more frequently in late winter during El Niño (La Niña) events (e.g., Pozo-Vázquez et al 2001;Moron and Plaut 2003;Gouirand and Moron 2003;Melo-Goncalves et al 2005;Brönnimann et al 2007;Gouirand et al 2007;Li and Lau 2012). Müller and Roeckner (2006) suggested that this kind of linkage between ENSO and the NAO could become stronger in the future.…”

Section: Introductionmentioning

confidence: 99%

High and low latitude types of the downstream influences of the North Atlantic Oscillation

Song

Zhou

2013

Clim Dyn

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Using reanalysis data, we find that the downstream-propagating quasi-stationary Rossby wave train associated with the North Atlantic Oscillation (NAO) generally propagates along a high (low)-latitude pathway during warm (cold) El Niño-Southern Oscillation (ENSO) boreal winters. Consistent with the different propagation directions of the NAO-related downstream wave train, during the warm (cold) ENSO winters, the NAO is associated with significant 300 hPa geopotential height anomalies over eastern Siberia (the Arabian Sea, the east coast of Asia at around 40°N, and the North Pacific), and the nearsurface air temperature perturbations associated with the NAO over the high latitudes of Asia are relatively strong (weak). Based on these differences, we argue that the NAO has two distinct types of downstream influence: a highlatitude type and a low-latitude type. Furthermore, we argue that the two types of NAO's downstream influence are modulated by the intensity of the subtropical potential vorticity (PV) meridional gradient over Africa. When this gradient is weak (strong), as in the warm (cold) ENSO winters, the NAO's downstream influence tends to be of the high (low)-latitude type. These results are further supported by analysis of intraseasonal NAO events. We separate NAO events into two categories in terms of the intensity of the subtropical PV gradient over Africa. Composites of the NAO events accompanied by a weak (strong) subtropical PV gradient show that the NAO-related downstream wave train tends to propagate along a high (low)-latitude pathway.

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The impact of El Niño–southern oscillation upon weather regimes over Europe and the North Atlantic during boreal winter

Cited by 83 publications

References 42 publications

Relationship between sea-level pressure and sea-level height in the Camargue (French Mediterranean coast)

Relationship between sea-level pressure and sea-level height in the Camargue (French Mediterranean coast)

Weather regimes and sea surge variations over the Gulf of Lions (French Mediterranean coast) during the 20th century

High and low latitude types of the downstream influences of the North Atlantic Oscillation

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