scholarly journals Changes in extreme temperature indices over the Peripannonian region of Bosnia and Herzegovina

Geografie ◽  
2019 ◽  
Vol 124 (1) ◽  
pp. 19-40
Author(s):  
Tatjana Popov ◽  
Slobodan Gnjato ◽  
Goran Trbić
Keyword(s):  
Bosnia And Herzegovina ◽  
Extreme Temperature ◽  
The Arctic ◽  
The North ◽  
Expert Team ◽  
Temperature Indices ◽  
Maximum Temperatures ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation ◽  
Cold Extremes

The paper analyzes changes in extreme temperature indices over the Peripannonian region of Bosnia and Herzegovina. Data on daily minimum and maximum temperatures during the period 1961–2016 from four meteorological stations were used for the calculation in the RClimDex (1.0) sopware trends in 16 indices recommended by the Expert team on climate change detection and indices. The estimated significant upward tendency in indices of warm extremes and downward in cold-related indices confirm that warming is present. The highest trend values were obtained for indices TXx, TNn, TN90p, TX90p, SU25, SU30 and WSDI. The results indicate significant distributional changes in the period 1987−2016 compared to the period 1961−1990. A significant positive (negative) correlation between the East-Atlantic pattern and indices of warm (cold) extremes was determined throughout the year. In winter and spring, significant links to the North Atlantic Oscillation and the Arctic Oscillation, respectively, were also found.

scholarly journals Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

2006 ◽  
Vol 63 (7) ◽  
pp. 1859-1877 ◽  
Author(s):  
D. Kondrashov ◽  
S. Kravtsov ◽  
M. Ghil
Keyword(s):  
Numerical Study ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
The Arctic ◽  
Reduced Model ◽  
The North ◽  
Low Frequency Variability ◽  
Intraseasonal Oscillations ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

The North Atlantic Oscillation and the Arctic Oscillation favour harmful algal blooms in SW Europe

Harmful Algae ◽  
2014 ◽  
Vol 39 ◽  
pp. 121-126 ◽  
Author(s):  
José C. Báez ◽  
Raimundo Real ◽  
Victoria López-Rodas ◽  
Eduardo Costas ◽  
A. Enrique Salvo ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Arctic Oscillation ◽  
The Arctic ◽  
The North ◽  
The North Atlantic ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

scholarly journals Spatiotemporal Variability and Trends in Extreme Temperature Events in Finland over the Recent Decades: Influence of Northern Hemisphere Teleconnection Patterns

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Masoud Irannezhad ◽  
Hamid Moradkhani ◽  
Bjørn Kløve
Keyword(s):  
Northern Hemisphere ◽  
Extreme Temperature ◽  
Cold Temperature ◽  
Spatiotemporal Variability ◽  
The Arctic ◽  
Temperature Extremes ◽  
Warm Temperature ◽  
Teleconnection Patterns ◽  
The North ◽  
Temperature Indices

Fifteen temperature indices recommended by the ETCCDI (Expert Team on Climate Change Detection and Indices) were applied to evaluate spatiotemporal variability and trends in annual intensity, frequency, and duration of extreme temperature statistics in Finland during 1961–2011. Statistically significant relationships between these high-resolution (10 km) temperature indices and seven influential Northern Hemisphere teleconnection patterns (NHTPs) for the interannual climate variability were also identified. During the study period (1961–2011), warming trends in extreme temperatures were generally manifested by statistically significant increases in cold temperature extremes rather than in the warm temperature extremes. As expected, warm days and nights became more frequent, while fewer cold days and nights occurred. The frequency of frost and icing days also decreased. Finland experienced more (less) frequent warm (cold) temperature extremes over the past few decades. Interestingly, significant lengthening in cold spells was observed over the upper part of northern Finland, while no clear changes are found in warm spells. Interannual variations in the temperature indices were significantly associated with a number of NHTPs. In general, warm temperature extremes show significant correlations with the East Atlantic and the Scandinavia patterns and cold temperature extremes with the Arctic Oscillation and the North Atlantic Oscillation patterns.

scholarly journals The influence of Arctic air masses on climatic conditions of the snow accumulation period in the center of the European territory of Russia

2021 ◽  
pp. 16-25
Author(s):  
Julia Nikolaevna Chizhova
Keyword(s):  
North Atlantic ◽  
Arctic Oscillation ◽  
Winter Precipitation ◽  
Climatic Conditions ◽  
The Arctic ◽  
Air Masses ◽  
The North ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation ◽  
The Relationship

The subject of this article is exmination of the influence of the Arctic air flow on the climatic conditions of the winter period in the center of the European territory of Russia (Moscow). In recent years, the question of the relationship between regional climatic conditions and such global circulation patterns as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AK) has become increasingly important. Based on the data of long-term observations of temperature and precipitation, the relationship with the AK and NAO was considered. For the winter months of the period 2014-2018, the back trajectories of the movement of air masses were computed for each date of precipitation to identify the sources of precipitation. The amount of winter precipitation that forms the snow cover of Moscow has no connection with either the North Atlantic Oscillation or the Arctic Oscillation. The Moscow region is located at the intersection of the zones of influence of positive and negative phases of both cyclonic patterns (AK and NAO), which determine the weather in the Northern Hemisphere. For the winter months, a correlation between the surface air temperature and NAO (r = 0.72) and AK (r = 0.66) was established. Winter precipitation in the center of the European territory of Russiais mainly associated with the unloading of Atlantic air masses. Arctic air masses relatively rarely invade Moscow region and bring little precipitation (their contribution does not exceed 12% of the total winter precipitation).

scholarly journals Analysis and Discussion of Atmospheric Precursor of European Heat Summers

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Christine Träger-Chatterjee ◽  
Richard W. Müller ◽  
Jörg Bendix
Keyword(s):  
Time Series ◽  
False Alarm ◽  
North Sea ◽  
Southern Oscillation ◽  
The Arctic ◽  
The Novel ◽  
The North ◽  
Spring Transition ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

The prediction of summers with notable droughts and heatwaves on the seasonal scale is challenging, especially in extratropical regions, since their development is not yet fully understood. Thus, monitoring and analysis of such summers are important tasks to close this knowledge gap. In a previous paper, the authors presented hints that extreme summers are connected with specific conditions during the winter-spring transition season. Here, these findings are further discussed and analysed in the context of the Earth’s circulation systems. No evidence for a connection between the North Atlantic Oscillation or the Arctic Oscillation during the winter-spring transition and extremely hot and dry summers is found. However, inspection of the geopotential at 850 hPa shows that a Greenland-North Sea-Dipole is connected with extreme summers in Central Europe. This motivated the introduction of the novel Greenland-North Sea-Dipole-Index, GNDI. However, using this index as predictor would lead to one false alarm and one missed event in the time series analysed (1958–2011). Hints are found that the disturbance of the “dipole-summer” connection is due to El Niño/Southern Oscillation (ENSO). To consider the ENSO effect, the novel Central European Drought Index (CEDI) has been developed, which is composed of the GNDI and the Bivariate ENSO Time Series Index. The CEDI enables a correct indication of all extremely hot and dry summers between 1958 and 2011 without any false alarm.

scholarly journals Reconsideration of the True versus Apparent Arctic Oscillation

2008 ◽  
Vol 21 (10) ◽  
pp. 2047-2062 ◽  
Author(s):  
Hisanori Itoh
Keyword(s):  
Spatial Correlation ◽  
Arctic Oscillation ◽  
Physical Reality ◽  
The Arctic ◽  
Sea Level Pressure ◽  
The North ◽  
The Pacific ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation ◽  
Almost All

Abstract The physical reality of the Arctic Oscillation (AO; or northern annular mode) is considered. The data used are mainly the monthly mean sea level pressure (SLP). A schematic figure is first presented to illustrate the relationship between the North Atlantic Oscillation (NAO)–Pacific–North American Oscillation (PNA) system and the AO–negative correlation mode between the Atlantic and the Pacific (AO–NCM) system. Although the NAO–PNA (apparent AO–NCM) and true AO–NCM systems give rise to the same EOFs, the probability density functions for the time coefficients of the two leading modes are different. Therefore, the discrimination of the two systems is possible. Several pieces of evidence indicate that, in the real world, the NAO–PNA and the AO–NCM are located on almost the same plane in phase space. This means that the NAO–PNA and AO–NCM systems have the same variations on the plane in common, implying that when the NAO–PNA system is real, the AO–NCM is unlikely to be real. Simple independent component analysis is carried out to distinguish between the true and apparent AO–NCM systems, indicating that the NAO and PNA are independent oscillations, that is, true ones. The analysis is extended to the winter mean SLP field, for which the EOF shows the NAO–PNA but not the AO–NCM. This may be due to the fact that the winter mean NAO and PNA patterns have little spatial correlation. Calculations using randomly selected samples also indicate that when the NAO and PNA patterns have little spatial correlation, the AO never appears as EOF1. All the preceding results show that almost all characteristics of the AO–NCM can be explained from those of the NAO–PNA. Hence it is concluded that the AO, which is extracted by EOF analysis from the temporarily independent but spatially overlapping variations of the NAO and PNA, is almost apparent.

scholarly journals Maximum temperatures over Slovenia and their relationship with atmospheric circulation patterns

Geografie ◽  
2017 ◽  
Vol 122 (1) ◽  
pp. 1-20 ◽  
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.

scholarly journals Changes in extreme climate indices in Sarajevo (Bosnia and Herzegovina)

2021 ◽  
Vol 101 (2) ◽  
pp. 1-21
Author(s):  
Slobodan Gnjato ◽  
Tatjana Popov ◽  
Marko Ivanisevic ◽  
Goran Trbic
Keyword(s):  
Bosnia And Herzegovina ◽  
Extreme Precipitation ◽  
Extreme Temperature ◽  
The Arctic ◽  
Climate Indices ◽  
East Atlantic ◽  
Extreme Climate ◽  
Extreme Precipitation Indices ◽  
Precipitation Indices ◽  
Temperature Indices

The study analyzes trends in extreme climate indices in Sarajevo (Bosnia and Herzegovina). Based on daily maximum temperatures, daily minimum temperatures and daily precipitation during the 1961-2016 periods, a set of 27 indices recommended by the CCl/CLIVAR Expert Team for Climate Change Detection and Indices (ETCCDI) was calculated in the RClimDex (1.0) software. Given the results, the extreme temperature indices displayed a warming tendency throughout the year (most prominent in summer). The positive trends in warm temperature indices were stronger than the downward trends in cold ones. The highest trend values were estimated for TXx, TNx, TX90p, TN90p, WSDI, SU25 and SU30. The extreme precipitation indices displayed trends mixed in sign (annually and seasonally), but all statistically insignificant. However, upward trends in R99p, RX1day, RX5day, SDII, R10mm and R20mm suggest an increase in the magnitude and frequency of intense precipitation events. Moreover, significant changes in distribution of majority temperature indices were determined, whereas shifts in precipitation indices were mostly insignificant. The observed changes in extreme temperature indices are related with large-scale atmospheric circulation patterns (primarily the East-Atlantic pattern) and the Atlantic Multidecadal Oscillation. The negative correlation with the North Atlantic Oscillation, the East Atlantic/West Russia pattern and the Arctic Oscillation is found for majority of extreme precipitation indices.

scholarly journals Predictability Associated with Nonlinear Regimes in an Atmospheric Model

2012 ◽  
Vol 69 (3) ◽  
pp. 1137-1154 ◽  
Author(s):  
John M. Peters ◽  
Sergey Kravtsov ◽  
Nicholas T. Schwartz
Keyword(s):  
Phase Space ◽  
Atmospheric Model ◽  
Flow Patterns ◽  
The Arctic ◽  
The North ◽  
Spreading Rates ◽  
The Arctic Oscillation ◽  
Non Gaussian ◽  
The North Atlantic Oscillation ◽  
The Relationship

Abstract Atmospheric regimes are midlatitude flow patterns that persist for periods of time exceeding a few days. Here, the authors analyzed the output of an idealized atmospheric model (QG3) to examine the relationship between regimes and predictability. The regimes were defined as the regions of the QG3 phase subspace characterized by excess persistence probability relative to a benchmark linear empirical model (EMR) for geographically two-dimensional and then zonally averaged flow patterns. The regimes identified correspond to the opposite phases of the Arctic Oscillation (AO+ and AO−) and to a more regional pattern reflecting the positive phase of the North Atlantic Oscillation (NAO+). For all of these phase-space regime regions, the leading modes of the QG3 state vector decay to climatology at a slower rate than predicted by the EMR, which contributes to the maintenance of non-Gaussian regime anomalies. Predictable regimes are connected to “regime precursor” regions of the phase space, from which trajectories flow into regime regions following mean phase-space velocities. Packets of trajectories originating from these regions are characterized by anomalously low spreading rates due to a combination of low local stochastic diffusivity and convergence of the nonlinear component of mean phase-space velocities along the trajectory pathways. While unpredictable regimes do have precursor regions, trajectories emanating from these regions are characterized by relatively high spreading rates. The predictable regimes AO+ and AO− are insensitive to the metric used to identify the regimes; however, the unpredictable regime NAO+ in the 2D space is not directly associated with its zonal-metric counterpart.

A breakdown of the link between the Arctic and North Atlantic Oscillations in warm climate projections

2020 ◽  
Author(s):  
Mostafa Hamouda ◽  
Claudia Pasquero ◽  
Eli Tziperman
Keyword(s):  
North Atlantic ◽  
Climate Scenario ◽  
Reanalysis Data ◽  
The Arctic ◽  
Climate Projections ◽  
Modes Of Variability ◽  
The North ◽  
Temperature And Precipitation ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

<table><tbody><tr><td>The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) are climate variability modes significantly affecting temperature and precipitation variability in the mid-latitudes of the Northern hemisphere. In this study, we use both reanalysis data and model historical and warmer climate simulations to show that the relation between the two oscillations may change dramatically in a different climate. In the current climate, these two climate modes are highly correlated, as they are both strongly influenced by downward propagation of stratospheric anomalies into the troposphere. When considering a warmer climate scenario (RCP8.5 in the XXIII century), the correlation between NAO and AO drops significantly, revealing that they become two separate modes of variability. The stratosphere remains an important precursor for NAO, while the AO consistently precede stratospheric anomalies. The analysis suggests that these changes are owed to land-sea thermal contrast intensification in the Pacific region, which becomes more favorable for storm variability.</td> </tr></tbody></table>

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