Classifications of winter atmospheric circulation patterns: validation of CMIP5 GCMs over Europe and the North Atlantic

Abstract. For a high latitude country like Sweden snowfall is an important contributor to the regional water cycle. Furthermore, snowfall impacts surface properties, affects atmospheric thermodynamics, has implications for traffic and logistics management, disaster preparedness, and also impacts climate through changes in surface albedo and turbulent heat fluxes. For Sweden it has been shown that large-scale atmospheric circulation patterns, or weather states, are important for precipitation variability. Although the link between atmospheric circulation patterns and precipitation has been investigated for rainfall there are no studied focused on the sensitivity of snowfall to weather states over Sweden. In this work we investigate the response of snowfall to eight selected weather states. These weather states consist of four dominant wind directions together with cyclonic and anti-cyclonic circulation patterns and enhanced positive and negative phases of the North Atlantic oscillation. The presented analysis is based on multiple data sources, such as ground-based radar measurements, satellite observations, spatially-interpolated in situ observations, and reanalysis data. The data from these sources converge to underline the sensitivity of falling snow over Sweden to the different weather states. In this paper we examine both average snowfall intensities and snowfall accumulations associated with the different weather states. It is shown that even though the heaviest snowfall intensities occur during conditions with winds from the southwest, the largest contribution to snowfall accumulation arrives from winds from the southeast. Large differences in snowfall due to variations in the North Atlantic oscillation are shown as well as a strong effect of cyclonic and anti-cyclonic circulation patterns. Satellite observations are used to reveal the vertical structures of snowfall during the different weather states.

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The sensitivity of snowfall to weather states over Sweden

Atmospheric Measurement Techniques ◽

10.5194/amt-10-3249-2017 ◽

2017 ◽

Vol 10 (9) ◽

pp. 3249-3263 ◽

Cited By ~ 1

Author(s):

Lars Norin ◽

Abhay Devasthale ◽

Tristan S. L'Ecuyer

Keyword(s):

North Atlantic Oscillation ◽

Atmospheric Circulation ◽

North Atlantic ◽

Satellite Observations ◽

Anticyclonic Circulation ◽

Atmospheric Circulation Patterns ◽

The North ◽

Circulation Patterns ◽

The North Atlantic ◽

The North Atlantic Oscillation

Abstract. For a high-latitude country like Sweden snowfall is an important contributor to the regional water cycle. Furthermore, snowfall impacts surface properties, affects atmospheric thermodynamics, has implications for traffic and logistics management, disaster preparedness, and also impacts climate through changes in surface albedo and turbulent heat fluxes. For Sweden it has been shown that large-scale atmospheric circulation patterns, or weather states, are important for precipitation variability. Although the link between atmospheric circulation patterns and precipitation has been investigated for rainfall there are no studies focused on the sensitivity of snowfall to weather states over Sweden.In this work we investigate the response of snowfall to eight selected weather states. These weather states consist of four dominant wind directions together with cyclonic and anticyclonic circulation patterns and enhanced positive and negative phases of the North Atlantic Oscillation. The presented analysis is based on multiple data sources, such as ground-based radar measurements, satellite observations, spatially interpolated in situ observations, and reanalysis data. The data from these sources converge to underline the sensitivity of falling snow over Sweden to the different weather states.In this paper we examine both average snowfall intensities and snowfall accumulations associated with the different weather states. It is shown that, even though the heaviest snowfall intensities occur during conditions with winds from the south-west, the largest contribution to snowfall accumulation arrives with winds from the south-east. Large differences in snowfall due to variations in the North Atlantic Oscillation are shown as well as a strong effect of cyclonic and anticyclonic circulation patterns. Satellite observations are used to reveal the vertical structures of snowfall during the different weather states.

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Recent Trends in the Recurrence of North Atlantic Atmospheric Circulation Patterns

Complexity ◽

10.1155/2018/3140915 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Pascal Yiou ◽

Julien Cattiaux ◽

Aurélien Ribes ◽

Robert Vautard ◽

Mathieu Vrac

Keyword(s):

Atmospheric Circulation ◽

North Atlantic ◽

Atmospheric Circulation Patterns ◽

The North ◽

Emerging Trends ◽

Circulation Patterns ◽

Long Term Trends ◽

Recent Trends ◽

The Stability ◽

Climate Events

A few types of extreme climate events in the North Atlantic region, such as heatwaves, cold spells, or high cumulated precipitation, are connected to the recurrence of atmospheric circulation patterns. Understanding those extreme events requires assessing long-term trends of the atmospheric circulation. This paper presents a set of diagnostics of the intra- and interannual recurrence of atmospheric patterns. Those diagnostics are devised to detect trends in the stability of the circulation and the return period of atmospheric patterns. We detect significant emerging trends in the winter circulation, pointing towards a potential increased predictability. No such signal seems to emerge in the summer. We find that the winter trends in the dominating atmospheric patterns and their recurrences do not depend of the patterns themselves.

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Linkages between atmospheric circulation, climate and streamflow in the northern North Atlantic: research prospects

Progress in Physical Geography Earth and Environment ◽

10.1191/0309133306pp471ra ◽

2006 ◽

Vol 30 (2) ◽

pp. 143-174 ◽

Cited By ~ 87

Author(s):

D. G. Kingston ◽

D. M. Lawler ◽

G. R. McGregor

Keyword(s):

Atmospheric Circulation ◽

North Atlantic ◽

Analytical Techniques ◽

Eastern Canada ◽

Natural Systems ◽

Atmospheric Circulation Patterns ◽

The North ◽

Circulation Patterns ◽

Northwest Europe ◽

The North Atlantic Oscillation

This paper evaluates the relationships between atmospheric circulation, climate and streamflow in the northern North Atlantic region over the last century and especially the last 50 years. Improved understanding of climatic influences on streamflow is vital given the great importance of fluvial processes to natural systems and water resources, especially in the light of recent and predicted climate change. The main focus lies with climatic and hydrologic implications of the major circulation patterns in the northern North Atlantic, namely the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO). The studies reviewed here reveal key relationships between circulation, climate and streamflow across the northern North Atlantic, allowing the construction of a simple conceptual model for this system. Generally positive NAO/AO-streamflow relationships are found in northwest Europe and northeast USA, with both positive and negative NAO/AO-streamflow linkages apparent for parts of eastern Canada. To help promote a better understanding of the system, several research gaps are identified and critically examined, including: the spatial scope and coverage of investigations; data quality and homogeneity; appropriateness of analytical techniques; and the need for greater knowledge and technique sharing between hydrology and climatology, particularly regarding the rigorous characterization of atmospheric circulation patterns. Among these, the development of seasonally varying, or mobile, NAO indices, to capture variations in subseasonal, seasonal and annual movements in the centres of action, and the need to develop analyses of more hydrologically meaningful climate variables beyond conventional time averaged statistics, are deemed particularly important.

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Strengthened Linkage between November/December North Atlantic Oscillation and Subsequent January European Precipitation after the Late 1980s

Journal of Climate ◽

10.1175/jcli-d-19-0662.1 ◽

2020 ◽

Vol 33 (19) ◽

pp. 8281-8300

Author(s):

Yang Liu ◽

Shengping He

Keyword(s):

North Atlantic Oscillation ◽

Atmospheric Circulation ◽

North Atlantic ◽

Storm Track ◽

Low Frequency ◽

Early Winter ◽

Atmospheric Circulation Patterns ◽

Internal Climate Variability ◽

The North ◽

The North Atlantic

AbstractThis work investigates the nonsynchronous relationship between the North Atlantic Oscillation (NAO) and winter European precipitation. The results indicate that the linkage between early-winter (November and December) NAO and the following January precipitation and atmospheric circulation over the North Atlantic and European sectors became statistically significant after the late 1980s. Before the late 1980s, January precipitation and atmospheric circulation are weakly correlated with early-winter NAO. After the late 1980s, by contrast, the positive phase of the early-winter NAO is generally followed by an anomalous meridional dipole pattern with barotropic structure over the North Atlantic, which provides conditions for more (less) precipitation south of Iceland (east of the Azores). Further analysis elucidates that this regime shift may be partly attributed to the change of early-winter NAO, which is concurrent with significant change in the intensity of the synoptic and low-frequency eddy interaction over the Atlantic–European sectors. Anomalous positive sea level pressure and geopotential height, along with zonal wind anomalies associated with a positive early-winter NAO over the North Atlantic, are more significant and extend more northeastward after the late 1980s, which may be induced by an intensified transient eddy feedback after the late 1980s, as well as the enhanced storm-track activity over the North Atlantic. Thus, early-winter NAO can induce significant ocean temperature anomalies in the North Atlantic after the late 1980s, which extend downward into the middle parts of the thermocline and persist until the following January to trigger NAO-like atmospheric circulation patterns. Analyses from the Community Earth System Model large ensemble simulations indicate the effects of internal climate variability on such a strengthened linkage.

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North Atlantic Jet position induces latitudinal decouplings in forest productivity in Europe

10.5194/egusphere-egu2020-19951 ◽

2020 ◽

Author(s):

Isabel Dorado-Liñán ◽

Valerie Trouet ◽

Keyword(s):

North Atlantic ◽

Large Scale ◽

European Beech ◽

Forest Productivity ◽

Atmospheric Circulation Patterns ◽

Summer Climate ◽

The North ◽

Circulation Patterns ◽

Latitudinal Position ◽

The North Atlantic

Dynamically-driven extreme weather events have large ecological, social and economic consequences including large tree-growth reductions and forest mortality. These events are likely to become globally more frequent and intense in the near future with increased anthropogenic forcing and associated changes in couple atmosphere-ocean circulation. The European continent is under the control of different atmospheric circulation patterns leading to geographical climatic gradients caused by their eventual position and strength, being the North Atlantic Oscillation (NAO) and the East Atlantic Pattern (EA) the main modes of North Atlantic climate variability (Barnston and Levezey 1987; Folland et al. 2009). Both, NAO and EA reflect jet stream changes as a consequence of variations in the eddy forcing, being the North Atlantic Jet (NAJ) the pattern connecting the large-scale atmospheric variability over the North Atlantic basin (Woollings, Hannachi, and Hoskins 2010). Thus, the identification and characterization of the links between forest productivity and the precursors of large-scale dynamics inducing extreme events may boost our capacity of assessing their predictability and enhancing forecasting skills. Here, we scale forest response to climate to higher atmospheric levels by establishing the connection between extreme positive and negative anomalies in productivity of European forests to the latitudinal position of the NAJ. For that, we use a network of 344 European beech tree-ring chronologies extending from the Iberian Peninsula to the Carpathians and from Greece to northern UK. Our results show a geographical gradient on tree growth across Europe explained either by the asymmetric forest response to homogeneous summer climate over Europe or to a distinct summer climate dipole leading to diverging climatic conditions in northeaster and southwestern Europe. In both cases, the continental-scale European-beech growth patterns are linked to the NAJ latitudinal position and its determinant influence on summer climate over Europe. The projected increase in the frequency of northward migrations of the NAJ for the next century may enhance the differences in forest productivity across Europe by inducing subcontinental-wide beech forest growth reduction. Barnston, Anthony Gaston, and Robert E. Levezey. 1987. "Classification, seasonality and persistence of low-frequency atmospheric circulation patterns" Mon. Weather Rev. 115: 1083-1126. Folland, Chris K, Jeff Knight, Hans W Linderholm, David Fereday, Sarah Ineson, and James W Hurrell. 2009. &#8220;The Summer North Atlantic Oscillation: Past, Present, and Future.&#8221; Journal of Climate 22 (5): 1082&#8211;1103. https://doi.org/10.1175/2008JCLI2459.1. Woollings, Tim, Abdel Hannachi, and Brian Hoskins. 2010. &#8220;Variability of the North Atlantic Eddy-Driven Jet Stream.&#8221; Quarterly Journal of the Royal Meteorological Society 136 (649): 856&#8211;68. https://doi.org/10.1002/qj.625.&#160;

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Can preferred atmospheric circulation patterns over the North-Atlantic-Eurasian region be associated with arctic sea ice loss?

Polar Science ◽

10.1016/j.polar.2017.09.002 ◽

2017 ◽

Vol 14 ◽

pp. 9-20 ◽

Cited By ~ 18

Author(s):

Berit Crasemann ◽

Dörthe Handorf ◽

Ralf Jaiser ◽

Klaus Dethloff ◽

Tetsu Nakamura ◽

...

Keyword(s):

Sea Ice ◽

North Atlantic ◽

Arctic Sea Ice ◽

Atmospheric Circulation Patterns ◽

The North ◽

Circulation Patterns ◽

Arctic Sea ◽

The North Atlantic ◽

Arctic Sea Ice Loss ◽

Eurasian Region

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Decadal Variability in a Central Greenland High-Resolution Deuterium Isotope Record and Its Relationship to the Frequency of Daily Atmospheric Circulation Patterns from the North Atlantic Region

Journal of Climate ◽

10.1175/2010jcli3556.1 ◽

2010 ◽

Vol 23 (17) ◽

pp. 4608-4618 ◽

Cited By ~ 7

Author(s):

Norel Rimbu ◽

Gerrit Lohmann

Keyword(s):

High Resolution ◽

North Atlantic ◽

Decadal Variability ◽

North Atlantic Region ◽

Atlantic Region ◽

Atmospheric Circulation Patterns ◽

The North ◽

Circulation Patterns ◽

Isotope Record ◽

The North Atlantic

Abstract The variability of an annual resolution deuterium time series from central Greenland is investigated in connection with the variability in the frequency of daily atmospheric circulation patterns in the North Atlantic region. Statistical analysis reveals that a large part of the decadal variability of the deuterium isotope record is related to decadal variability in the frequency of several identified daily circulation patterns. The study shows that these circulation patterns induce variations in the deuterium record by altering where isotopic fractionation occurs, mainly during the passage of the associated air masses over continental areas. The study identifies three significant periodic components in the deuterium isotope record at ∼12, ∼20, and ∼30 yr. It also shows that the ∼20-yr signal in the deuterium isotope record is related to the variability in the frequency of a winter circulation type. An analysis of six oxygen isotope records from central Greenland reveals decadal variations similar to the deuterium isotope record. The authors argue that high-resolution stable isotope records from Greenland ice cores can be used to obtain information about the frequency of certain daily circulation patterns during past periods.

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