Relationship between winter orographic precipitation with synoptic and large-scale atmospheric circulation: The case of mount Olympus, Greece

The relationship between the winter (DJFM) precipitation and the atmospheric circulation patterns is examined around Mount Olympus, Greece in order to assess the effects of orography and atmospheric dynamics over a small (less than 100 x 100 km) spatial domain. Winter accumulated rainfall datasets from 8 stations spread along the eastern (marine) and western (continental) sides of the Mount Olympus at elevations between 30 m and 1150 m are used during the period 1981 to 2000. Synoptic scale conditions of mean sea-level pressure and geopotential heights at 850 hPa and 500 hPa, were used to explain the multiyear rainfall variability. High pressure systems dominated over the central Mediterranean and most parts of central Europe during the late 1980’s and early 1990’s, are associated with minimum winter rainfall along both sides of Mount Olympus. The winter of 1996 was associated with peak in rainfall along the marine side of the mountain and was characterized by enhancement of upper level trough over the western Mediterranean and increased low tropospheric depressions over the southern Adriatic and the Ionian Seas. This atmospheric circulation pattern facilitated a southeasterly air flow that affected more (less) the marine (continental) sides of the mountain. In contrast, dominance of low pressure systems with cores over the Gulf of Genoa and the Central Mediterranean affect the study area mostly from west/southwest revealing higher correlations with the precipitation in the continental side of the mountain (r= -0.80; Elassona station) and considerably lower correlations with the marine side (r = -0.67; Katerini station). This highlights the orographic barrier of the Mount Olympus revealing large differences between the upward and leeward sides. Large scale atmospheric patterns like the North Atlantic Oscillation and the Arctic Oscillation seem to influence the winter rainfall in the lowlands along the continental side of the mountain.

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Large-scale climate signals of a European oxygen isotope network from tree rings

Climate of the Past ◽

10.5194/cp-17-1005-2021 ◽

2021 ◽

Vol 17 (3) ◽

pp. 1005-1023

Author(s):

Daniel F. Balting ◽

Monica Ionita ◽

Martin Wegmann ◽

Gerhard Helle ◽

Gerhard H. Schleser ◽

...

Keyword(s):

Atmospheric Circulation ◽

Tree Ring ◽

Tree Rings ◽

Large Scale ◽

Southern Oscillation ◽

Circulation Pattern ◽

Isotopic Signature ◽

Atmospheric Circulation Patterns ◽

The North ◽

Instrumental Records

Abstract. We investigate the climate signature of δ18O tree-ring records from sites distributed all over Europe covering the last 400 years. An empirical orthogonal function (EOF) analysis reveals two distinct modes of variability on the basis of the existing δ18O tree-ring records. The first mode is associated with anomaly patterns projecting onto the El Niño–Southern Oscillation (ENSO) and reflects a multi-seasonal climatic signal. The ENSO link is pronounced for the last 130 years, but it is found to be weak over the period from 1600 to 1850, suggesting that the relationship between ENSO and the European climate may not be stable over time. The second mode of δ18O variability, which captures a north–south dipole in the European δ18O tree-ring records, is related to a regional summer atmospheric circulation pattern, revealing a pronounced centre over the North Sea. Locally, the δ18O anomalies associated with this mode show the same (opposite) sign with temperature (precipitation). Based on the oxygen isotopic signature derived from tree rings, we argue that the prevailing large-scale atmospheric circulation patterns and the related teleconnections can be analysed beyond instrumental records.

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Impacts of large-scale atmospheric circulation changes due to winter sea-ice retreat on Black Carbon transport and deposition to the Arctic

10.5194/acp-2016-1007 ◽

2016 ◽

Author(s):

Luca Pozzoli ◽

Srdan Dobricic ◽

Simone Russo ◽

Elisabetta Vignati

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

North Atlantic ◽

Large Scale ◽

Southern Oscillation ◽

The Arctic ◽

The North ◽

Ice Retreat ◽

The North Atlantic Oscillation ◽

Sea Ice Retreat

Abstract. Winter warming and sea ice retreat observed in the Arctic in the last decades determine changes of large scale atmospheric circulation pattern that may impact as well the transport of black carbon (BC) to the Arctic and its deposition on the sea ice, with possible feedbacks on the regional and global climate forcing. In this study we developed and applied a new statistical algorithm, based on the Maximum Likelihood Estimate approach, to determine how the changes of three large scale weather patterns (the North Atlantic Oscillation, the Scandinavian Blocking, and the El Nino-Southern Oscillation), associated with winter increasing temperatures and sea ice retreat in the Arctic, impact the transport of BC to the Arctic and its deposition. We found that the three atmospheric patterns together determine a decreasing winter deposition trend of BC between 1980 and 2015 in the Eastern Arctic while they increase BC deposition in the Western Arctic. The increasing trend is mainly due to the more frequent occurrences of stable high pressure systems (atmospheric blocking) near Scandinavia favouring the transport in the lower troposphere of BC from Europe and North Atlantic directly into to the Arctic. The North Atlantic Oscillation has a smaller impact on BC deposition in the Arctic, but determines an increasing BC atmospheric load over the entire Arctic Ocean with increasing BC concentrations in the upper troposphere. The El Nino-Southern Oscillation does not influence significantly the transport and deposition of BC to the Arctic. The results show that changes in atmospheric circulation due to polar atmospheric warming and reduced winter sea ice significantly impacted BC transport and deposition. The anthropogenic emission reductions applied in the last decades were, therefore, crucial to counterbalance the most likely trend of increasing BC pollution in the Arctic.

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Changes in precipitation over the East Herzegovina region

Glasnik srpskog geografskog drustva ◽

10.2298/gsgd1901029p ◽

2019 ◽

Vol 99 (1) ◽

pp. 29-44 ◽

Cited By ~ 1

Author(s):

Tatjana Popov ◽

Slobodan Gnjato ◽

Goran Trbic

Keyword(s):

Large Scale ◽

Winter Season ◽

Rainfall Anomaly ◽

Downward Trend ◽

The Arctic ◽

Seasonal Precipitation ◽

Atmospheric Circulation Patterns ◽

Autumn Season ◽

The North ◽

The North Atlantic Oscillation

Changes in annual and seasonal precipitation over the East Herzegovina region in Bosnia and Herzegovina during the 1961-2016 periods were analyzed based on data sets of daily precipitation from 14 meteorological stations and rainfall gauges. The results show a downward trend in annual precipitation over the entire East Herzegovina region. Seasonal trend analysis showed that negative trends prevailed throughout the year, except in autumn season. Most prominent negative trends were registered in summer season throughout the region. In winter and spring season, precipitation displayed trends of both sign (although a downward trend prevailed). In the autumn season, precipitation has increased almost throughout the entire East Herzegovina region. However, a majority of estimated trends in annual and seasonal precipitation were weak and statistically insignificant. Prevailing negative values of the Rainfall Anomaly Index since the 1990s also suggest that precipitation reduction was present over the East Herzegovina region. Analysis of the Cumulative Precipitation Anomalies showed that a dry period started in 1981 and still continues. Precipitation variability was strongly dictated by the large-scale atmospheric circulation patterns over the Northern Hemisphere, such as the North Atlantic Oscillation, the East Atlantic/West Russia pattern and the Arctic Oscillation, particularly during winter season.

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Recent Extreme Arctic Temperatures are due to a Split Polar Vortex

Journal of Climate ◽

10.1175/jcli-d-16-0320.1 ◽

2016 ◽

Vol 29 (15) ◽

pp. 5609-5616 ◽

Cited By ~ 44

Author(s):

James E. Overland ◽

Muyin Wang

Keyword(s):

Atmospheric Circulation ◽

Geopotential Height ◽

Polar Vortex ◽

Circulation Pattern ◽

Arctic Sea Ice ◽

The Arctic ◽

Arctic Amplification ◽

The North ◽

Central Eurasia ◽

Arctic Temperature

Abstract There were extensive regions of Arctic temperature extremes in January and February 2016 that continued into April. For January, the Arctic-wide averaged temperature anomaly was 2.0°C above the previous record of 3.0°C based on four reanalysis products. Midlatitude atmospheric circulation played a major role in producing such extreme temperatures. Extensive low geopotential heights at 700 hPa extended over the southeastern United States, across the Atlantic, and well into the Arctic. Low geopotential heights along the Aleutian Islands and a ridge along northwestern North America contributed southerly wind flow. These two regions of low geopotential height were seen as a major split in the tropospheric polar vortex over the Arctic. Warm air advection north of central Eurasia reinforced the ridge that split the flow near the North Pole. Winter 2015 and 2016 geopotential height fields represented an eastward shift in the longwave atmospheric circulation pattern compared to earlier in the decade (2010–13). Certainly Arctic amplification will continue, and 2016 shows that there can be major Arctic contributions from midlatitudes. Whether Arctic amplification feedbacks are accelerated by the combination of recent thinner, more mobile Arctic sea ice and occasional extreme atmospheric circulation events from midlatitudes is an interesting conjecture.

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Decadal Variability in the Impact of Atmospheric Circulation Patterns on the Winter Climate of Northern Russia

Journal of Climate ◽

10.1175/jcli-d-20-0566.1 ◽

2021 ◽

Vol 34 (3) ◽

pp. 1005-1021

Author(s):

Gareth J. Marshall

Keyword(s):

Atmospheric Circulation ◽

Decadal Variability ◽

The Arctic ◽

Temporal Consistency ◽

Atmospheric Circulation Patterns ◽

The North ◽

Dominant Pattern ◽

Circulation Patterns ◽

Northern Russia ◽

The Impact

AbstractThe Arctic continues to warm at a much faster rate than the global average. One process contributing to “Arctic amplification” involves changes in low-frequency macroscale atmospheric circulation patterns and their consequent influence on regional climate. Here, using ERA5 data, we examine decadal changes in the impact of seven such patterns on winter near-surface temperature (SAT) and precipitation (PPN) in northern Russia and calculate the temporal consistency of any statistically significant relationships. We demonstrate that the 40-yr climatology hides considerable decadal variability in the spatial extent of such circulation pattern–climate relationships across the region, with few areas where their temporal consistency exceeds 60%. This is primarily a response to the pronounced decadal expansion/contraction and/or mobility of the circulation patterns’ centers of action. The North Atlantic Oscillation (NAO) is the dominant pattern (having the highest temporal consistency) affecting SAT west of the Urals. Farther east, the Scandinavian (SCA), Polar/Eurasian (POL), and West Pacific patterns are successively the dominant pattern influencing SAT across the West Siberian Plains, Central Siberian Plateau, and mountains of Far East Siberia, respectively. From west to east, the SCA, POL, and Pacific–North American patterns exert the most consistent decadal influence on PPN. The only temporally invariant significant decadal relationships occur between the NAO and SAT and the SCA and PPN in small areas of the North European Plain.

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Changes in stability and jumps in Dansgaard–Oeschger events: a data analysis aided by the Kramers–Moyal equation

10.5194/esd-2021-95 ◽

2021 ◽

Author(s):

Leonardo Rydin Gorjão ◽

Keno Riechers ◽

Forough Hassanibesheli ◽

Dirk Witthaut ◽

Pedro G. Lind ◽

...

Keyword(s):

Atmospheric Circulation ◽

Ice Cores ◽

Arctic Region ◽

The Arctic ◽

Atmospheric Circulation Patterns ◽

The North ◽

Circulation Patterns ◽

Fold Bifurcation ◽

North Atlantic Climate ◽

Paleoclimate Records

Abstract. Dansgaard–Oeschger (DO) events are sudden climatic shifts from cold to substantially milder conditions in the arctic region that occurred during previous glacial intervals. They can be most clearly identified in paleoclimate records of δ18O and dust concentrations from Greenland ice cores, which serve as proxies for temperature and atmospheric circulation patterns, respectively. The existence of stadial (cold) and interstadial (milder) phases is typically attributed to a bistability of the North Atlantic climate system allowing for rapid transitions from the first to the latter and a more gentle yet still fairly abrupt reverse shift from the latter to the first. However, the underlying physical mechanisms causing these transitions remain debated. Here, we conduct a data-driven analysis of the Greenland temperature and atmospheric circulation proxies under the purview of stochastic processes. Based on the Kramers–Moyal equation we present a one-dimensional and two-dimensional derivation of the proxies' drift and diffusion terms, which unravels the features of the climate system's stability landscape. Our results show that: (1) in contrast to common assumptions, the δ18O proxy results from a monostable process, and transitions occur in the record only due to the coupling to other variables; (2) conditioned on δ18O the dust concentrations exhibit both mono and bistable states, transitioning between them via a double-fold bifurcation; (3) the δ18O record is discontinuous in nature, and mathematically requires an interpretation beyond the classical Langevin equation. These findings can help understand candidate mechanisms underlying these archetypal examples of abrupt climate changes.

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Greenland accumulation and its connection to the large-scale atmospheric circulation in ERA-Interim and paleoclimate simulations

Climate of the Past ◽

10.5194/cp-9-2433-2013 ◽

2013 ◽

Vol 9 (6) ◽

pp. 2433-2450 ◽

Cited By ~ 18

Author(s):

N. Merz ◽

C. C. Raible ◽

H. Fischer ◽

V. Varma ◽

M. Prange ◽

...

Keyword(s):

Atmospheric Circulation ◽

Large Scale ◽

Climate Model ◽

Ice Core ◽

Ice Cores ◽

Circulation Pattern ◽

Large Scale Circulation ◽

Atmospheric Circulation Patterns ◽

The Stability ◽

The Relationship

Abstract. Changes in Greenland accumulation and the stability in the relationship between accumulation variability and large-scale circulation are assessed by performing time-slice simulations for the present day, the preindustrial era, the early Holocene, and the Last Glacial Maximum (LGM) with a comprehensive climate model. The stability issue is an important prerequisite for reconstructions of Northern Hemisphere atmospheric circulation variability based on accumulation or precipitation proxy records from Greenland ice cores. The analysis reveals that the relationship between accumulation variability and large-scale circulation undergoes a significant seasonal cycle. As the contributions of the individual seasons to the annual signal change, annual mean accumulation variability is not necessarily related to the same atmospheric circulation patterns during the different climate states. Interestingly, within a season, local Greenland accumulation variability is indeed linked to a consistent circulation pattern, which is observed for all studied climate periods, even for the LGM. Hence, it would be possible to deduce a reliable reconstruction of seasonal atmospheric variability (e.g., for North Atlantic winters) if an accumulation or precipitation proxy were available that resolves single seasons. We further show that the simulated impacts of orbital forcing and changes in the ice sheet topography on Greenland accumulation exhibit strong spatial differences, emphasizing that accumulation records from different ice core sites regarding both interannual and long-term (centennial to millennial) variability cannot be expected to look alike since they include a distinct local signature. The only uniform signal to external forcing is the strong decrease in Greenland accumulation during glacial (LGM) conditions and an increase associated with the recent rise in greenhouse gas concentrations.

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Maximum temperatures over Slovenia and their relationship with atmospheric circulation patterns

Geografie ◽

10.37040/geografie2017122010001 ◽

2017 ◽

Vol 122 (1) ◽

pp. 1-20 ◽

Cited By ~ 4

Author(s):

Dragan D. Milošević ◽

Stevan M. Savić ◽

Uglješa Stankov ◽

Igor Žiberna ◽

Milana M. Pantelić ◽

...

Keyword(s):

Atmospheric Circulation ◽

Southern Oscillation ◽

The Arctic ◽

Maximum Temperature ◽

East Atlantic ◽

Atmospheric Circulation Patterns ◽

The North ◽

Circulation Patterns ◽

Maximum Temperatures ◽

The North Atlantic Oscillation

This paper examines temporal and spatial patterns of annual and seasonal maximum temperatures (Tmax) in Slovenia and their relationship with atmospheric circulation patterns. A significant increase in maximum temperature (Tmax; from 0.3°C to 0.5°C·decade-1) was observed throughout the country at the annual scale in the period 1963–2014. Significant positive trends are observed on all stations in summer (from 0.4°C to 0.7°C·decade-1) and spring (from 0.4°C to 0.6°C·decade-1). The results indicate significant correlations between the mean annual maximum temperature (Tmax) and the East Atlantic Oscillation (EA) (from 0.5 to 0.7), the Arctic Oscillation (AO) (from 0.4 to 0.7) and the Scandinavian Oscillation (SCAND) (from −0.3 to −0.4) throughout the country. A significant EA influence is observed in all seasons, while the AO influence is noticed in winter and spring, SCAND in spring and summer, the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) in winter, the East Atlantic/Western Russia Oscillation (EA/WR) in summer and the El Nino Southern Oscillation (ENSO) in autumn.

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Changes in sea-surface temperature and atmospheric circulation patterns associated with reductions in Arctic sea ice cover in recent decades

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-14149-2018 ◽

2018 ◽

Vol 18 (19) ◽

pp. 14149-14159 ◽

Cited By ~ 3

Author(s):

Lejiang Yu ◽

Shiyuan Zhong

Keyword(s):

Sea Ice ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Atmospheric Circulation ◽

Large Scale ◽

Arctic Sea Ice ◽

Sea Surface ◽

The Arctic ◽

Atmospheric Circulation Patterns ◽

Arctic Sea

Abstract. In recent decades, the Arctic sea ice has been declining at a rapid pace as the Arctic warms at a rate of twice the global average. The underlying physical mechanisms for the Arctic warming and accelerated sea ice retreat are not fully understood. In this study, we apply a relatively novel statistical method called self-organizing maps (SOM) along with composite analysis to examine the trend and variability of autumn Arctic sea ice in the past three decades and their relationships to large-scale atmospheric circulation changes. Our statistical results show that the anomalous autumn Arctic dipole (AD) (Node 1) and the Arctic Oscillation (AO) (Node 9) could explain in a statistical sense as much as 50 % of autumn sea ice decline between 1979 and 2016. The Arctic atmospheric circulation anomalies associated with anomalous sea-surface temperature (SST) patterns over the North Pacific and North Atlantic influence Arctic sea ice primarily through anomalous temperature and water vapor advection and associated radiative feedback.

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Contributions from intrinsic low-frequency climate variability to the accelerated decline in Arctic sea ice in recent decades

10.5194/acp-2018-127 ◽

2018 ◽

Author(s):

Lejiang Yu ◽

Shiyuan Zhong

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

Large Scale ◽

Low Frequency ◽

Arctic Sea Ice ◽

The Arctic ◽

Self Organizing Maps ◽

The North ◽

Arctic Sea ◽

Atmospheric Circulation Anomalies

Abstract. In recent decades, the Arctic sea ice has been declining at a rapid pace as the Arctic is warmed at a rate of twice the global average. The underlying physical mechanisms for the Arctic warming and accelerated sea ice retreat are not fully understood. In this study, we apply a relatively novel statistical method called Self-Organizing Maps (SOM) to examine the trend and variability of autumn Arctic sea ice in the past four decades and their relationships to large-scale atmospheric circulation changes. Our results show a large portion of the autumn Arctic sea ice decline between 1979 and 2016 may be associated with anomalous autumn Arctic intrinsic atmospheric modes. The Arctic atmospheric circulation anomalies associated with anomalous sea surface temperature patterns over the North Pacific and North Atlantic influence Arctic sea ice primarily through anomalous temperature and water vapor advection and associated radiative feedback.

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