Pluri-Decadal Variability of Fluvio-Glacial Dynamics Across Heinrich Stadial 1: Dinocyst Evidence for Seasonality Changes in Western Europe

Abstract. Several major storms pounded western Europe in January 2018, generating large damages and casualties. The two most impactful ones, Eleanor and Friederike, are analysed here in the context of climate change. Near surface wind speed station observations exhibit a decreasing trend in the frequency of strong winds associated with such storms. High-resolution regional climate models, on the other hand, show no trend up to now and a small increase in storminess in future due to climate change. This shows that factors other than climate change, which are not in the climate models, caused the observed decline in storminess over land. A large part is probably due to increases in surface roughness, as shown for a small set of stations covering the Netherlands and in previous studies. This observed trend could therefore be independent from climate evolution. We concluded that human-induced climate change has had so far no significant influence on storms like the two mentioned. However, all simulations indicate that global warming could lead to a marginal increase (0 %–20 %) in the probability of extreme hourly winds until the middle of the century, consistent with previous modelling studies. This excludes other factors, such as surface roughness, aerosols, and decadal variability, which have up to now caused a much larger negative trend. Until these factors are correctly simulated by climate models, we cannot give credible projections of future storminess over land in Europe.

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Maximum growing season temperature in Western Europe: multi proxy reconstructions in Fontainebleau from 1596 to 2000

Climate of the Past Discussions ◽

10.5194/cpd-3-1063-2007 ◽

2007 ◽

Vol 3 (5) ◽

pp. 1063-1117 ◽

Cited By ~ 1

Author(s):

N. Etien ◽

V. Daux ◽

V. Masson-Delmotte ◽

M. Stievenard ◽

V. Bernard ◽

...

Keyword(s):

Western Europe ◽

Decadal Variability ◽

Growing Season ◽

Temperature Data ◽

Maximum Temperature ◽

Atmospheric Models ◽

Documentary Sources ◽

Proxy Reconstructions ◽

Temporal Coherency

Abstract. In this study, we have combined a Burgundy grape harvest date record with new δ18O measurements conducted on timbers and living trees cellulose from Fontainebleau castle and forest. Our reconstruction is expected to provide a reference series for the variability of growing season temperature (from April to September) in Western Europe from 1596 to 2000. We have estimated an uncertainty of 0.55°C on individual growing season maximum temperature reconstructions. We are able to assess this uncertainty, which is not the case for many documentary sources (diaries etc.), and even not the case for early instrumental temperature data. We compare our data with a number of independent temperature estimates for Europe and the Northern Hemisphere. The comparison between our reconstruction and Manley mean growing season temperature data provides an independent control of the quality of CET data. We show that our reconstruction preserves more variance back in time, because it was not distorted/averaged by statistical/homogenisation methods. Further works will be conducted to compare the δ18O data from wood cellulose provided by transects of different tree species in Europe obtained within the EC ISONET project and the French ANR Program ESCARSEL, to analyse the spatial and temporal coherency between δ18O records. The decadal variability will be also compared with other precipitation δ18O records such as those obtained from benthic ostracods from deep peri-Alpine lakes or simulated by regional atmospheric models equipped with the modelling of water stable isotopes.

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On the Rivers in the Euro-Atlantic Sky

10.21203/rs.3.rs-48633/v1 ◽

2020 ◽

Author(s):

Venugopal Thandlam ◽

Anna Rutgersson ◽

Erik Sahlee

Keyword(s):

Water Vapour ◽

North Atlantic ◽

Western Europe ◽

Decadal Variability ◽

Moisture Flux ◽

Lower Atmosphere ◽

Specific Humidity ◽

Spatiotemporal Variability ◽

The North ◽

The North Atlantic

Abstract We study and revisit the Atmospheric Rivers (AR) over Euro-Atlantic sky using long term reanalysis datasets and widely used methods and parameters. The atmospheric winds, temperature and specific humidity at different pressure levels during 1979-2018 were used to study the spatiotemporal variability of water vapour transport integrated between 1000-300 hPa (IVT300) as a proxy to ARs. The standard deviation (200 kgm-1s-1) of ARs is around 60% of the climatology (>300 kgm-1s-1) in all reanalysis datasets in the North Atlantic. High frequency of ARs over western Europe in winter half-year (WHY) has 6% lower intensity compared to the low frequency of ARs in summer half-year (SHY) with 3% higher intensity than the annual mean. The intensity of ARs in the North Atlantic has been increasing in recent times with large decadal variability and poleward shift in landfalling. The magnitude of atmospheric parameters in the lower atmosphere below 750 hPa dominates the total column water vapour and intensity of ARs. There is a significant impact of the North Atlantic Oscillation and Scandinavian blocking on the location of landfalling of ARs and latitudinal dependence of the source of moisture flux in the open ocean contributing to the formation and enhancing ARs strength.

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Human influence on European winter wind storms such as those of January 2018

10.5194/esd-2018-57 ◽

2018 ◽

Author(s):

Robert Vautard ◽

Geert Jan van Oldenborgh ◽

Friederike E. L. Otto ◽

Pascal Yiou ◽

Hylke de Vries ◽

...

Keyword(s):

Climate Change ◽

Western Europe ◽

Climate Models ◽

Decadal Variability ◽

Regional Climate ◽

Surface Wind ◽

Regional Climate Models ◽

Surface Wind Speed ◽

Near Surface ◽

Modelling Studies

Abstract. Several major storms pounded Western Europe in January 2018, generating large damages and casualties. The two most impactful ones, Eleanor and Friederike, are analyzed here in the context of climate change. Near surface wind speed station observations exhibit a decreasing trend of the frequency of strong winds associated with such storms. High-resolution regional climate models on the other hand show no trend up to now and a small increase in the future due to climate change. This shows that that factors other than climate change, which are not represented (well) in the climate models, caused the observed decline in storminess over land. A large part is probably due to increases in surface roughness, as shown for a small set of stations covering The Netherlands and in previous studies. This trend could therefore be independent from climate evolution. We concluded that human-induced climate change has had so far no significant influence on storms like the two studied. However, all simulations indicate that global warming could lead to a marginal increase (0–20 %) of the probability of extreme hourly winds until the middle of the century, consistent with previous modelling studies. However, this excludes other factors, such as roughness, aerosols, and decadal variability, which have up to now caused a much larger negative trend. Until these factors are simulated well by climate models they cannot give credible projections of future storminess over land in Europe.

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On the Rivers in the Euro-Atlantic Sky

10.21203/rs.3.rs-48633/v3 ◽

2020 ◽

Author(s):

Venugopal Thandlam ◽

Anna Rutgersson ◽

Erik Sahlee

Keyword(s):

Water Vapour ◽

North Atlantic ◽

Western Europe ◽

Decadal Variability ◽

Moisture Flux ◽

Lower Atmosphere ◽

Specific Humidity ◽

Spatiotemporal Variability ◽

The North ◽

The North Atlantic

Abstract We study the spatiotemporal variability of Atmospheric Rivers (ARs) over Euro-Atlantic region using long-term reanalysis datasets. Winds, temperature and specific humidity at different pressure levels during 1979-2018 are used to study the water vapour transport integrated between 1000-300 hPa (IVT300) as a proxy to ARs. The intensity of ARs in the North Atlantic has been increasing in recent times (2009-2018) with large decadal variability and poleward shift (~5o towards the North) in landfall (1999-2018). Significant bias shown by different reanalysis products in IVT300 compared to ERA5 data is attributed to bias in specific humidity and winds. Different reanalysis datasets show similar spatial patterns of IVT300 in mapping ARs but has a bias of around 40-60 kgm-1s-1 compared to ERA5. The magnitude of winds and specific humidity in the lower atmosphere (below 750 hPa) dominates the total column water vapour and intensity of Ars in the north Atlantic. IVT300 in all reanalysis datasets in the North Atlantic show a standard deviation of 200 kgm-1s-1 which is around 60% of the IVT300 climatology (>300 kgm-1s-1). Though ARs have higher frequency of landfalling over Western Europe in winter half-year (WHY); the intensity of IVT300 in winter is 3% lower than the annual mean. On the other hand, lower frequency of ARs in summer half-year (SHY) shows 3% higher intensity than the annual mean. There is a significant impact of the North Atlantic Oscillation (NAO) and Scandinavian blocking on the location of landfall of ARs. Furthermore, there is a strong latitudinal dependence of the source of moisture flux in the open ocean, contributing to the formation and enhancing AR's strength.

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On the Rivers in the Euro-Atlantic Sky

10.21203/rs.3.rs-48633/v2 ◽

2020 ◽

Author(s):

Venugopal Thandlam ◽

Anna Rutgersson ◽

Erik Sahlee

Keyword(s):

Water Vapour ◽

North Atlantic ◽

Western Europe ◽

Decadal Variability ◽

Moisture Flux ◽

Lower Atmosphere ◽

Specific Humidity ◽

Spatiotemporal Variability ◽

The North ◽

The North Atlantic

Abstract We study and revisit the Atmospheric Rivers (AR) over Euro-Atlantic sky using long term reanalysis datasets and widely used methods and parameters. The atmospheric winds, temperature and specific humidity at different pressure levels during 1979-2018 were used to study the spatiotemporal variability of water vapour transport integrated between 1000-300 hPa (IVT300) as a proxy to ARs. The standard deviation (200 kgm-1s-1) of ARs is around 60% of the climatology (>300 kgm-1s-1) in all reanalysis datasets in the North Atlantic. High frequency of ARs over western Europe in winter half-year (WHY) has 6% lower intensity compared to the low frequency of ARs in summer half-year (SHY) with 3% higher intensity than the annual mean. The intensity of ARs in the North Atlantic has been increasing in recent times with large decadal variability and poleward shift in landfalling. The magnitude of atmospheric parameters in the lower atmosphere below 750 hPa dominates the total column water vapour and intensity of ARs. There is a significant impact of the North Atlantic Oscillation and Scandinavian blocking on the location of landfalling of ARs and latitudinal dependence of the source of moisture flux in the open ocean contributing to the formation and enhancing ARs strength.

Download Full-text