scholarly journals Atmospheric circulation types in Marmara Region (NW Turkey) and their influence on precipitation

2014 ◽  
Vol 35 (8) ◽  
pp. 1810-1820 ◽  
Author(s):  
H. Baltacı ◽  
O. M. Göktürk ◽  
T. Kındap ◽  
A. Ünal ◽  
M. Karaca
Keyword(s):  
Atmospheric Circulation ◽  
Marmara Region ◽  
Circulation Types ◽  
Nw Turkey

Velocity changes across the Ganos segment of the North Anatolian Fault Zone in NW Turkey from systematic variations in body wave arrival times

2021 ◽  
Author(s):  
Esref Yalcinkaya ◽  
Marco Bohnhoff ◽  
Patricia Martinez-Garzon ◽  
Ethem Görgün ◽  
Ali Pınar ◽  
...  
Keyword(s):  
Body Wave ◽  
Waveform Analysis ◽  
Marmara Region ◽  
Rupture Directivity ◽  
Data Set ◽  
High Resolution Data ◽  
Arrival Times ◽  
The North ◽  
Nw Turkey ◽  
Geological Units

<p>Imaging and characterizing transform fault sections that are capable to produce large earthquakes is crucial for evaluating seismic hazard and subsequent risk for nearby population centers. The Marmara Fault near the megacity of Istanbul is one of the best defined seismic gaps in the world and its complexity is captured by seismological, geodetic and geological data. A local dense seismic array (MONGAN) provides a high resolution data set allowing to image the Ganos fault separating two different geological units in the western Marmara region. First results of the waveform analysis from this array present systematic early-phase arrivals at the seismic stations located on the northern block of the Ganos fault which comprises geological units including older and more compact materials than that of the southern block. This difference in the arrival times causes the earthquake epicenters to shift further north than the real locations. In this preliminary results, the early-arrivals will be evaluated according to source azimuths and distances, and possible earth models and wave paths will be discussed. The results have implications for rupture directivity during future earthquakes as input for hazard and risk models for the Marmara region.</p>

scholarly journals Relationships of surface air temperature anomalies over Europe to persistence of atmospheric circulation patterns conducive to heat waves

2008 ◽  
Vol 14 ◽  
pp. 243-249 ◽  
Author(s):  
J. Kyselý ◽  
R. Huth
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Heat Waves ◽  
Temperature Extremes ◽  
Human Society ◽  
Positive Temperature ◽  
Temperature Anomalies ◽  
Circulation Types ◽  
Circulation Patterns ◽  
Air Temperature Anomalies

Abstract. Heat waves are among natural hazards with the most severe consequences for human society, including pronounced mortality impacts in mid-latitudes. Recent studies have hypothesized that the enhanced persistence of atmospheric circulation may affect surface climatic extremes, mainly the frequency and severity of heat waves. In this paper we examine relationships between the persistence of the Hess-Brezowsky circulation types conducive to summer heat waves and air temperature anomalies at stations over most of the European continent. We also evaluate differences between temperature anomalies during late and early stages of warm circulation types in all seasons. Results show that more persistent circulation patterns tend to enhance the severity of heat waves and support more pronounced temperature anomalies. Recent sharply rising trends in positive temperature extremes over Europe may be related to the greater persistence of the circulation types, and if similar changes towards enhanced persistence affect other mid-latitudinal regions, analogous consequences and implications for temperature extremes may be expected.

Near-fault seismic monitoring reveals the long-lasting activation of a local fault in the Marmara region controlled by slow slip 

2021 ◽  
Author(s):  
Patricia Martínez-Garzón ◽  
Virginie Durand ◽  
Stephan Bentz ◽  
Taylan Turkmen ◽  
Grzegorz Kwiatek ◽  
...  
Keyword(s):  
Temporal Distribution ◽  
Marmara Region ◽  
Slow Slip ◽  
Fault Rupture ◽  
Aseismic Slip ◽  
Seismic Sequences ◽  
Near Fault ◽  
Aftershock Sequences ◽  
Nw Turkey ◽  
Different Characteristics

<p>Recent laboratory and field observations show that fault seismic and aseismic slip may occur concurrently. Here, we combine microseismicity recordings from a temporary near-fault seismic network (SMARTnet) and borehole strainmeter data from the eastern Marmara region in NW Turkey to track seismic and aseismic deformation around the hypocentral region of a M<sub>W</sub> 4.5 earthquake that occurred in 2018. The strainmeter data show a clear strain signal transient starting at the time of the M<sub>W</sub> 4.5 event and lasting for about 150 days. We study about 1,200 microseismic events following the mainshock within and beyond the mainshock fault rupture. The temporal distribution of the seismicity reveals a strong temporal clustering, including four semi-periodic seismic sequences each containing more than 50 events in two days. Two seismic sequences occurred during the strain transient showing different characteristics compared to two sequences occurring afterwards. Seismicity occurring during the transient displayed typical characteristics driven by aseismic slip, such as the activation of a broader region from the mainshock, and the absence of a clear mainshock in each sequence. Seismic sequences occurring after the transient correspond to typical mainshock-aftershock sequences and activated a region closer to the original M<sub>W</sub> 4.5 mainshock. We suggest post-strain transient seismicity originate from stress redistribution and breaking of remaining asperities. Our observations from a newly installed combined dense seismic and strainmeter network in the eastern Sea of Marmara region allows identifying repeated triggering of aseismic transients within an observation period of three years suggesting these may occur more often than previously thought.</p>

scholarly journals Climatic characteristics of summer human thermal discomfort in Athens and its connection to atmospheric circulation

2013 ◽  
Vol 13 (12) ◽  
pp. 3271-3279 ◽  
Author(s):  
A. Bartzokas ◽  
C. J. Lolis ◽  
P. A. Kassomenos ◽  
G. R. McGregor
Keyword(s):  
Pressure Gradient ◽  
Atmospheric Circulation ◽  
Aegean Sea ◽  
The Other ◽  
Thermal Discomfort ◽  
Circulation Types ◽  
Light Wind ◽  
Discomfort Index ◽  
Climatic Characteristics ◽  
Weather Characteristics

Abstract. The climate characteristics of summer human thermal discomfort in Athens and its connection to atmospheric circulation are studied for the period 1954–2012. The human thermal discomfort is examined in terms of the Predicted Mean Vote (PMV) discomfort index for calm and light wind (3 ms-1) conditions. Its inter-annual variability is characterised by a significant increase from the middle 1980s to the end of the study period. The onset and the cessation of the discomfort period are found to take place around the beginning of July and the end of August respectively, but from middle 1980s the dates of onset and cessation have slightly moved earlier and later, respectively, leading to a longer summer discomfort period. The connection between human thermal discomfort and atmospheric circulation is studied by examining the distribution of discomfort cases across six objectively defined circulation types over Europe, based on Athens weather characteristics. High values of the PMV discomfort index are mainly associated with two typical high-summer pressure patterns with the intensity of discomfort depending on the pressure gradient over the Aegean Sea. On the contrary, low PMV discomfort index values prevail mainly on days typified by the other four circulation types, which are more frequent during May, June, and September.

scholarly journals Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1690 ◽  
Author(s):  
Renata Graf ◽  
Dariusz Wrzesiński
Keyword(s):  
Water Temperature ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Statistical Significance ◽  
Winter Season ◽  
Circulation Type ◽  
River Waters ◽  
Positive And Negative Coefficients ◽  
Circulation Types ◽  
Temporal And Spatial Variability

The objective of the paper consisted in determining the effect of macroscale types of NAO, AO, EA, EAWR, SCAND, and AMO atmospheric circulation on changes in water temperature in Polish rivers. The study has made use of a broad body of hydrometeorological materials covering daily water temperature values for 96 water gauge stations located on 53 rivers and air temperature values for 43 meteorological stations. Percentage shares of positive and negative coefficients of correlation of annual, seasonal, and monthly circulation type indices with air and river water temperature were determined, demonstrating the character of teleconnection. Determinations were made of water temperature deviations in positive and negative phases of the analyzed indices from average values from the years 1971–2015, and their statistical significance ascertained. Research has shown that relations between the temperature of river waters in Poland and macroscale circulation types are not strong, however they are noticeable, sometimes even statistically significant, and both temporally and spatially diverse. NAO, AO, EA, and AMO indices are characterized by a generally positive correlation with temperature, whereas SCAND and EWAR indices are characterized by a negative correlation. Research showed a varying impact of types of atmospheric circulation, with their effectiveness increasing in the winter season. The strongest impact on temperature was observed for the positive and negative NAO and AO phases, when deviations of water temperature from average values are correspondingly higher (up to 1.0 °C) and lower (by a maximum of 1.5 °C), and also for the positive and negative SCAND phases, when water temperature are correspondingly lower (by a maximum of 0.8 °C) and higher (by 1.2 °C) than average values. The strongest impact on water temperature in summer, mainly in July, was observed for AMO. The results point to the complexity of processes determining the thermal regime of rivers and to the possibility of additional factors—both regional and local—exerting an influence on their temporal and spatial variability.

Spatio-temporal changes of drought in Romania (1961-2015), according to atmospheric circulation types and teleconnection indices

2020 ◽  
Author(s):  
Radu-Vlad Dobri ◽  
Liviu Apostol ◽  
Lucian Sfîcă ◽  
Simona Țîmpu ◽  
Ion-Andrei Niță
Keyword(s):  
Atmospheric Circulation ◽  
Standardized Precipitation Index ◽  
Atmospheric Precipitation ◽  
Climatic Conditions ◽  
Extreme Drought ◽  
Drought Severity ◽  
Severe Drought ◽  
Circulation Types ◽  
Teleconnection Indices ◽  
Moderate Drought

<p>Drought can be determined by climatic conditions (atmospheric precipitation, water supply from soil accessible to the plant, moisture and air temperature and wind speed) but is also induced by environmental aspects some of them related to anthropogenic influences.</p><p>In order to monitor the drought and its impact for Romania, four indices were analyzed in the present study (SPI (Standardized Precipitation Index), PNI (Percent of Normal Index), DI (Deciles index), and ZSI (Z-score Index)), through Meteorological Drought Monitoring software, using the total daily amount of precipitation for 27 weather stations in Romania, of which 22 stations for the period 1961-2015, 4 stations for the period 1961-2000 and one station for the period 1964-2015.</p><p>Preliminary analyzes resulting from the use of these indices were correlated with 18 GWT (Großwettertypen) atmospheric circulation types of daily mean sea level pressure (SLP). This was done using COST733 class software to evaluate the influence of large-scale mechanisms of atmospheric circulation. Also, four teleconnection indices were used, more exactly AO (Arctic Oscillation), NAO (North Atlantic Oscillation), PNA (Pacific-North American Pattern) and AAO (Antarctic Oscillation) that are recognized for their effect on climatic conditions at European scale,  <br>provided by National Oceanic and Atmospheric Administration (NOAA) – Climate Prediction Center.</p><p>Therefore, according to the types of circulation, the amount of precipitation produced in certain areas and implicitly the degree of drought severity is influenced. The types of anticyclonal circulation 13, 16 or 18, for example, which occur on average in 46 (12.7%), 14 (3.9%) , respectively 20 (5.4%) days a year, cause less precipitation as known, compared to the types of cyclonal circulation 1, 2 or 17 for example with an average of 12 (3.2%), 12 (3.2%), respectively 19 (4.3%) days a year.</p><p>In terms of drought analysis indices, according to SPI, the entire analysis interval for Iasi, located in the northeast region of Romania, was 6 years of "moderately dry", 5 years of "severely dry", and one year of "extremely dry", unlike Cluj, located in the central western region, with two years of "moderately dry", 3 years of "severely dry" and two years of "extremely dry". In Bucharest, located in the southern region of Romania there were 4 "moderately dry" years and 5 "severely dry" years. In Iasi, according to the ZSI index with the same classifications as the SPI index, there were 3 "moderately drought" years, 7 "severely drought" years and 7 "extreme drought" years, while in Cluj there were 9, 3 and respectively 6 years and in Bucharest 7, 5 and respectively 6 years with the above classification.</p><p>According to the PNI index, there were 5 "moderate drought" years in Iasi and Cluj and 6 "moderate drought" years in Bucharest. Also, there were 9 "weak drought" years in Iasi, 3 in Cluj and 5 in Bucharest.</p><p>And last but not least, according to the DI index, at all 3 stations there were 5 "extreme drought" years, 6 "severe drought" years and 5 "moderate drought" years.</p>

scholarly journals The Climatology, precipitation types and atmospheric conditions of extreme precipitation events in western Turkey

2018 ◽  
Author(s):  
Bulent Oktay Akkoyunlu ◽  
Hakki Baltaci ◽  
Mete Tayanc
Keyword(s):  
Eastern Mediterranean ◽  
Balkan Peninsula ◽  
Marmara Region ◽  
Atmospheric Conditions ◽  
Pressure Center ◽  
Western Turkey ◽  
Average Value ◽  
Circulation Types ◽  
Extreme Precipitation Events ◽  
Rugged Topography

Abstract. This paper investigates the climatology, precipitation types and background physical mechanisms of extreme precipitations events (EPEs) over western Turkey during the period 2006–2015. The EPEs are described as the precipitation values above the 90th percentile obtained from the hourly precipitation dataset having high spatial resolution. Precipitation types associated with EPEs are identified by using radar outputs and Lamb Weather Type (LWT) approach. It is found that EPEs occurred more frequently in the Marmara and Aegean regions during autumn and winter months. In Marmara, mainly 21 %, 17 % and 15 % of total autumn EPEs are observed as convective (E circulation types (CTs)), cyclonic (C), and sea-effect (NE) extreme precipitations (EPs), in order. While convective EPEs are generally more active in the southern portions having rugged topography, cyclonic and sea effect EPs are more effective in the southwest and northeastern parts of Marmara. Among these three precipitation types, convective CTs produce more intense daily precipitation in the Marmara region with daily average value of 66.1 mm. Based on the hourly observations, convective types of EP which developed by the interaction between high pressure center over Balkan Peninsula and low pressure center over eastern Mediterranean, show two peak values during afternoon and evening times of the day and are linked to diurnal heating. In terms of Aegean region, cyclonic originated EPs, which include 65 % of the total winter EPEs, are more common in the whole territory and reach to its peak value during the first hours of the day.

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