Large-scale circulation classification, weather regimes, and local climate over France, the Alps and Western Europe

Impact of weather regimes on wind power variability in western Europe

10.5194/egusphere-egu2020-18797 ◽

2020 ◽

Author(s):

Ricardo García-Herrera ◽

Jose M. Garrido-Perez ◽

Carlos Ordóñez ◽

David Barriopedro ◽

Daniel Paredes

Keyword(s):

High Resolution ◽

Wind Speed ◽

Wind Energy ◽

Wind Power ◽

Large Scale ◽

Western Europe ◽

Power Production ◽

Large Scale Circulation ◽

Weather Regimes ◽

The Uk

We have examined the applicability of a new set of 8 tailored weather regimes (WRs) to reproduce wind power variability in Western Europe. These WRs have been defined using a substantially smaller domain than those traditionally used to derive WRs for the North Atlantic-European sector, in order to maximize the large-scale circulation signal on wind power in the region of study. Wind power is characterized here by wind capacity factors (CFs) from a meteorological reanalysis dataset and from high-resolution data simulated by the Weather Research and Forecasting (WRF) model. We first show that WRs capture effectively year-round onshore wind power production variability across Europe, especially over northwestern / central Europe and Iberia. Since the influence of the large-scale circulation on wind energy production is regionally dependent, we have then examined the high-resolution CF data interpolated to the location of more than 100 wind farms in two regions with different orography and climatological features, the UK and the Iberian Peninsula. The use of WRs allows discriminating situations with varied wind speed distributions and power production in both regions. In addition, the use of their monthly frequencies of occurrence as predictors in a multi-linear regression model allows explaining up to two thirds of the month-to-month CF variability for most seasons and sub-regions. These results outperform those previously reported based on Euro-Atlantic modes of atmospheric circulation. The improvement achieved by the spatial adaptation of WRs to a relatively small domain seems to compensate for the reduction in explained variance that may occur when using yearly as compared to monthly or seasonal WR classifications. In addition, our annual WR classification has the advantage that it allows applying a consistent group of WRs to reproduce day-to-day wind speed variability during extreme events regardless of the time of the year. As an illustration, we have applied these WRs to two recent periods such as the wind energy deficit of summer 2018 in the UK and the surplus of March 2018 in Iberia, which can be explained consistently by the different combinations of WRs.

Download Full-text

Relation between Large-Scale Circulation and European Winter Temperature: Does It Hold under Warmer Climate?

Journal of Climate ◽

10.1175/2010jcli3166.1 ◽

2010 ◽

Vol 23 (13) ◽

pp. 3752-3760 ◽

Cited By ~ 9

Author(s):

K. Goubanova ◽

L. Li ◽

P. Yiou ◽

F. Codron

Keyword(s):

Large Scale ◽

Winter Temperature ◽

Small Scale ◽

Large Scale Circulation ◽

Local Climate ◽

Temperature Changes ◽

Weather Regimes ◽

High Resolution Models ◽

The Individual ◽

The Impact

Abstract The idea of using large-scale information to predict local climate variability is widely exploited in climate change impact studies as an alternative to computationally expensive high-resolution models. This approach implies the hypothesis that the statistical relationship between large-scale climate states and local variables defined for the present-day climate remains valid in the altered climate. In this paper, the concept of weather regimes is used to deduce a relationship between large-scale circulation and European winter temperature. The change in temperature with increased greenhouse gases is, however, not homogeneous among the individual regimes. As a result, the impact of the weather regimes on local temperature changes varies in the future, limiting its usefulness for refining temperature changes to the small scale.

Download Full-text

Enhancement of seasonal hydrological forecasting with “pattern-based” large-scale climatology

10.5194/egusphere-egu21-7727 ◽

2021 ◽

Author(s):

Wei Yang ◽

Kean Foster ◽

Ilias G. Pechlivanidis

Keyword(s):

Large Scale ◽

Fuzzy Rule ◽

River System ◽

Reanalysis Data ◽

Streamflow Prediction ◽

Seasonal Forecasts ◽

Local Climate ◽

Weather Regimes ◽

Hydrological Forecasting ◽

Teleconnection Indices

The hydrological forecasting on seasonal (up to 7 months ahead) timescales is needed for decision-making in the hydropower sector. Being one of the vital influencing factors on hydro-production, a lot of development in dynamical forecasting at seasonal timescales has been done recently. However, the forecast bias still remains in different variables and consequently the skill of corresponding streamflow forecasts varies from month to month.This study aims to explore the potential for &#8220;pattern-based&#8221; seasonal hydrological forecasts that make use of hydrological weather regimes and teleconnection indices to improve forecast skill. The work is built on the hypothesis that hydrological weather regimes and teleconnection indices can be used to select analogue years (setting an ensemble) from a record of historical precipitation and temperature data with which to force a hydrological model to generate tailored seasonal forecasts of reservoir inflows. The hydrological weather regimes have been classified based on the concept of fuzzy sets using the anomalies of daily mean sea level pressure from reanalysis data (i.e., ERA-Interim). Precipitation records, measured in the Ume&#228;lven river basin during 1981-2016 are used as local observations to optimize each fuzzy rule that describes a type of &#8220;average&#8221; variability of local climate in terms of the frequency and magnitude of precipitation events. The teleconnection indices are compiled from the Climate Prediction Center, which describe global atmospheric variability. The methodology has been applied to 84 sub-catchments across seven of the most important hydropower producing river systems in Northern Sweden. However, the performance for the Ume&#228;lven river system is of particular interest here.Comparing to the traditional Ensemble Streamflow Prediction (ESP) method, the &#8220;pattern-based&#8221; seasonal hydrological forecasting shows a marked improvement, which is likely due to the weighted analogue-ESP approach as well as the selected analogues using the large-scale climate information described by hydrological weather regimes and teleconnection indices. The general performance of the two different approaches for selecting the analogues are similar; however, occasionally there are large differences in both the best analysis lead times and the spread of skill across the sub-catchments suggesting that those results are achieved using analogues based on different physical processes.

Download Full-text

Past Evolution and Recent Changes in Western Europe Large-scale Circulation

10.5194/wcd-2021-69 ◽

2021 ◽

Author(s):

Antoine Blanc ◽

Juliette Blanchet ◽

Jean-Dominique Creutin

Keyword(s):

Large Scale ◽

Western Europe ◽

Weather Conditions ◽

Large Scale Circulation ◽

Zonal Flows ◽

Important Challenge ◽

Key Driver ◽

Height Fields ◽

In The Beginning ◽

Local Weather

Abstract. Detecting trends in regional large-scale circulation (LSC) is an important challenge as LSC is a key driver of local weather conditions. In this work, we investigate the past evolution of Western Europe LSC based on the 500 hPa geopotential height fields from 20CRv2c (1851–2010), ERA20C (1900–2010) and ERA5 (1950–2010) reanalyses. We focus on the evolution of large-scale circulation characteristics using three atmospheric descriptors that are based on analogy – characterizing the geopotential shape stationarity and how well a geopotential shape is reproduced in the climatology – together with a non-analogy descriptor accounting for the intensity of the centers of action. These descriptors were shown relevant to study precipitation extremes and variability in the Northwestern Alps in previous studies. Even though LSC characteristics and trends are consistent among the three reanalyses after 1950, we find major differences between 20CRv2c and ERA20C from 1900 to 1950 in accordance with previous studies. Notably, ERA20C produces flatter geopotential shapes in the beginning of the 20th century and shows a reinforcement of the meridional pressure gradient that is not observed in 20CRv2c. We then focus on the recent changes in LSC from 1950 to 2019 using ERA5. We combine the four atmospheric descriptors with an existing weather pattern classification to study the recent changes in the main atmospheric influences over France and Western Europe (Atlantic, Mediterranean, Northeast, Anticyclonic). We show that little changes are found in Northeast circulations. However, we show that Atlantic circulations (zonal flows) tend to become more similar to known Atlantic circulations in winter. Anticyclonic conditions tend to become more stationary in summer – a change that can potentially affect summer heatwaves. Furthermore, Mediterranean circulations tend to become more stationary, more similar to known Mediterranean circulations and associated with stronger centers of action in autumn, which could have implications for autumn extreme precipitation in the Mediterranean-influenced regions of the Southwestern Alps.

Download Full-text

The role of North Atlantic–European weather regimes in the surface impact of sudden stratospheric warming events

Weather and Climate Dynamics ◽

10.5194/wcd-1-373-2020 ◽

2020 ◽

Vol 1 (2) ◽

pp. 373-388 ◽

Cited By ~ 4

Author(s):

Daniela I. V. Domeisen ◽

Christian M. Grams ◽

Lukas Papritz

Keyword(s):

North Atlantic ◽

Large Scale ◽

Western Europe ◽

Storm Track ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Weather Regimes ◽

The North ◽

Flow Evolution ◽

The North Atlantic

Abstract. Sudden stratospheric warming (SSW) events can significantly impact tropospheric weather for a period of several weeks, in particular in the North Atlantic–European (NAE) region. While the stratospheric forcing often projects onto the North Atlantic Oscillation (NAO), the tropospheric response to SSW events, if any, is highly variable, and what determines the existence, location, timing, and strength of the downward impact remains an open question. We here explore how the variable tropospheric response to SSW events in the NAE region can be characterized in terms of a refined set of seven weather regimes and if the tropospheric flow in the North Atlantic region around the onset of SSW events is an indicator of the subsequent downward impact. The weather regime analysis reveals the Greenland blocking (GL) and Atlantic trough (AT) regimes as the most frequent large-scale patterns in the weeks following an SSW. While the GL regime is dominated by high pressure over Greenland, AT is dominated by a southeastward-shifted storm track in the North Atlantic. The flow evolution associated with GL and the associated cold conditions over Europe in the weeks following an SSW occur most frequently if a blocking situation over western Europe and the North Sea (European blocking) prevailed around the SSW onset. In contrast, an AT regime associated with mild conditions over Europe is more likely following the SSW event if GL occurs already around SSW onset. For the remaining tropospheric flow regimes during SSW onset we cannot identify a dominant flow evolution. Although it remains unclear what causes these relationships, the results suggest that specific tropospheric states in the days around the onset of the SSW are an indicator of the subsequent tropospheric flow evolution in the aftermath of an SSW, which could provide crucial guidance for subseasonal prediction.

Download Full-text

The role of North Atlantic-European weather regimes in the surface impact of sudden stratospheric warming events

10.5194/wcd-2019-16 ◽

2020 ◽

Author(s):

Daniela I. V. Domeisen ◽

Christian M. Grams ◽

Lukas Papritz

Keyword(s):

North Atlantic ◽

Large Scale ◽

Western Europe ◽

Storm Track ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Weather Regimes ◽

The North ◽

The North Atlantic

Abstract. Sudden stratospheric warming (SSW) events can significantly impact tropospheric weather for a period of several weeks, in particular over the North Atlantic and Europe. However, not all SSW events exhibit the same tropospheric response, if any, and it remains an open question what determines the existence, location, timing, and strength of the downward impact. We here explore the role of the state of the tropospheric flow in the North Atlantic region at the onset of SSW events for determining the subsequent surface impact. A refined definition of seven North Atlantic tropospheric weather regimes indicates the Greenland blocking (GL) and Atlantic Trough (AT) regimes as the most frequent large-scale patterns following the weeks after an SSW. While GL is dominated by high pressure over Greenland, AT is dominated by a southeastward shifted storm track in the North Atlantic. We find that a blocking situation over western Europe and the North Sea (European Blocking) at the time of the SSW onset favours the GL response and the associated cold conditions over Europe. In contrast, an AT response and mild conditions are more likely if GL occurs already at SSW onset. For the remaining tropospheric flow regimes during SSW onset, we find no clear response. The results indicate that the tropospheric impact of SSW events critically depends on the tropospheric state during the onset of the SSW, which could provide crucial guidance for subseasonal prediction.

Download Full-text

Rossby wave activity associated with Euro-Atlantic weather regimes in the PRIMAVERA historical runs.

10.5194/egusphere-egu21-9605 ◽

2021 ◽

Author(s):

Paolo Ghinassi ◽

Federico Fabiano ◽

Susanna Corti

Keyword(s):

Spatial Distribution ◽

High Resolution ◽

Rossby Wave ◽

Large Scale ◽

Wave Activity ◽

Large Scale Circulation ◽

Temporal Behaviour ◽

Weather Regime ◽

Weather Regimes ◽

Isentropic Coordinates

In this study we aim to assess how the upper tropospheric Rossby wave activity is represented in the PRIMAVERA models. The low and high resolution historical coupled simulations will be compared with ERA5 reanalysis (spanning the 1979-2014 period) to enlighten model deficiencies in representing the spatial distribution and temporal evolution of Rossby wave activity and to emphasize the benefits of increased resolution. Our analysis focuses on the wintertime large scale circulation over the Euro-Atlantic sector. A diagnostic based on Local Wave Activity (LWA) in isentropic coordinates is used to identify Rossby waves and to quantify their amplitude. LWA is partitioned into its stationary and transient components, to distinguish the contribution from planetary versus synoptic scale waves (i.e. wave packets). This diagnostic is then combined with another one to identify persistent and recurrent large scale circulation patterns, the so called weather regimes. Weather regimes in the Euro-Atlantic sector are identified with the usual approach of EOF decomposition and k-mean clustering applied to daily anomalies of Montgomery streamfunction, in order to have a consistent framework with LWA (which is defined in isentropic coordinates). A composite of transient LWA is realised for each weather regime to obtain the spatial distribution of Rossby wave activity associated with each weather regime.Results show a marked intermodel variability in the ability of reproducing the correct (i.e. the one observed in reanalysis data) LWA distribution. Many of the models in fact fails to reproduce the localized (in space) maxima of LWA associated with each weather regime and to distribute LWA over a larger region compared to reanalysis. High resolution helps to correct this bias in the majority of the models, in particular in those where the low-resolution LWA distribution was already close to reanalysis. Finally, the temporal behaviour of the spatially averaged LWA in the examined period is discussed.

Download Full-text

Linking Large-scale Circulation Descriptors to Precipitation Variability in the Northern French Alps

10.5194/ems2021-224 ◽

2021 ◽

Author(s):

Antoine Blanc ◽

Juliette Blanchet ◽

Jean-Dominique Creutin

Keyword(s):

Pressure Difference ◽

Large Scale ◽

Western Europe ◽

Precipitation Variability ◽

Medium Size ◽

Maximum Pressure ◽

Large Scale Circulation ◽

French Alps ◽

Mountainous Catchment ◽

The North

This work analyses the link between Western Europe large-scale circulation and precipitation variability in the Northern French Alps from 1950 to 2017. We consider simple descriptors characterizing the daily 500hPa geopotential height fields. They are the Maximum Pressure Difference - representing the range of geopotential heights over Western Europe -, and the singularity - representing the mean distance between a geopotential shape and its closest analogs, i.e. the way this geopotential shape is reproduced in the climatology. These descriptors are compared to the occurrence of different atmospheric influences - Atlantic, Mediterranean, Northeast, Anticyclonic - and to the leading mode of large-scale circulation variability over Europe - the North Atlantic Oscillation (NAO) - for explaining precipitation variability in the Is&#232;re River catchment from one day to 10 years. We show that the Maximum Pressure Difference and the singularity of geopotential shapes explain a significant part of precipitation variability in the Northern French Alps from 10 days to 10 years, especially in winter (correlation values of 0.7). These descriptors provide much better performance than NAO and the same performance as the occurrence of the Atlantic influence, which is the best performing atmospheric influence. This means that simple characteristics of large-scale circulation - that are easy to implement - provide as much information as weather pattern classification to explain precipitation variability over a medium size mountainous catchment. Furthermore, we show that NAO does not drive the pressure gradient in a domain spreading from the Iberic Peninsula to Southern Great Britain and weakly explains precipitation variability in the Northern French Alps.

Download Full-text

Large-Scale Weather Regimes and Local Climate over the Western United States

Journal of Climate ◽

10.1175/1520-0442(1999)012<1796:lswral>2.0.co;2 ◽

1999 ◽

Vol 12 (6) ◽

pp. 1796-1813 ◽

Cited By ~ 75

Author(s):

Andrew W. Robertson ◽

Michael Ghil

Keyword(s):

United States ◽

Large Scale ◽

Western United States ◽

Local Climate ◽

Weather Regimes

Download Full-text

Linking Large-scale Circulation Descriptors to Precipitation Variability in the Northern French Alps

10.5194/egusphere-egu21-12881 ◽

2021 ◽

Author(s):

Antoine Blanc ◽

Juliette Blanchet ◽

Jean-Dominique Creutin

Keyword(s):

Pressure Difference ◽

Large Scale ◽

Western Europe ◽

Precipitation Variability ◽

Maximum Pressure ◽

Large Scale Circulation ◽

French Alps ◽

The North ◽

Height Fields ◽

The North Atlantic Oscillation

This work analyses the link between Western Europe large-scale circulation and precipitation variability in the Northern French Alps from 1950 to 2017. We consider simple descriptors characterizing the daily 500hPa geopotential height fields. They are the Maximum Pressure Difference - representing the range of geopotential heights over Western Europe -, and the singularity - representing the mean distance between a geopotential shape and its closest analogs, i.e. the way this geopotential shape is reproduced in the climatology. These descriptors are compared to the occurrence of different atmospheric influences - Atlantic, Mediterranean, Northeast, Anticyclonic - and to the leading mode of large-scale circulation variability over Europe - the North Atlantic Oscillation (NAO) - for explaining precipitation variability in the Is&#232;re River catchment from one day to 10 years. We show that the Maximum Pressure Difference and the singularity of geopotential shapes explain a significant part of precipitation variability in the Northern French Alps from 10 days to 10 years, especially in winter (correlation values of 0.7). These descriptors provide much better performance than NAO and the same performance as the occurrence of the Atlantic influence, which is the best performing atmospheric influence. This means that simple characteristics of large-scale circulation - that are easy to implement - provide as much information as weather pattern classification to explain precipitation variability in the Northern French Alps.

Download Full-text