Trends and possible causes of cloudiness variability in Montenegro in the period 1961-2017

2020 ◽  
Vol 81 ◽  
pp. 187-205
Author(s):  
D Burić ◽  
G Stanojević
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Northern Region ◽  
Western Mediterranean ◽  
Trend Detection ◽  
Positive Trend ◽  
East Atlantic ◽  
Regional Patterns ◽  
Precipitation Total ◽  
Mediterranean Oscillation

Cloudiness is an important climate parameter, and it is closely related to insolation, temperature, and precipitation. Total cloud cover (TCC) data along with the number of cloudless (CL) and overcast (OC) days from 18 stations in Montenegro during the period 1961-2017 were used to determine the seasonal trends and possible causes of cloudiness variability. The Mann-Kendall test and Sen’s slope were used for trend detection. We found statistically significant (p < 0.05 and p < 0.10) decreasing (increasing) trends in TCC (the number of CL days) in winter, spring and summer. The exception was in autumn, when an increase (decrease) in the TCC (CL days) was shown, but in most cases, these changes were insignificant. The number of OC days declined in coastal and central regions, while a positive trend was found in the northern region for all seasons. The increase in the number of CL days during the summer and winter was more pronounced compared to the decreasing trend in the number of OC days. Pearson’s correlation (r) was used to access the relationship between cloudiness and principal modes of atmospheric variability such as North Atlantic Oscillation (NAO), Summer North Atlantic Oscillation (SNAO), Arctic Oscillation (AO), East Atlantic Oscillation (EA), East Atlantic-West Russian Oscillation (EAWR), Scandinavian Pattern (SCAND), Polar-Eurasian Oscillation (POLEUR), North Sea-Caspian Pattern (NCP), and South Oscillation (SOI) as well as regional patterns of climate variability—the Mediterranean Oscillation (MOI) and Western Mediterranean Oscillation (WeMO). A significant consistency (r > 0.60, p < 0.05) was found between time series of certain atmospheric circulation patterns and cloud parameters (NAO, AO, EAWR, SCAND, NCP, and MOI-1), especially in the colder half of the year.

scholarly journals Contrasting Signals of the Westerly Index and North Atlantic Oscillation over the Drought Sensitivity of Tree-Ring Chronologies from the Mediterranean Basin

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 644 ◽  
Author(s):  
Pablo Casas-Gómez ◽  
Raúl Sánchez-Salguero ◽  
Pedro Ribera ◽  
Juan C. Linares
Keyword(s):  
North Atlantic Oscillation ◽  
Tree Ring ◽  
North Atlantic ◽  
Tree Species ◽  
Ring Width ◽  
Pinus Nigra ◽  
Western Mediterranean ◽  
Drought Severity ◽  
Drought Sensitivity ◽  
Westerly Index

Extreme drought events are becoming increasingly frequent and extended, particularly in Mediterranean drought-prone regions. In this sense, atmospheric oscillations patterns, such as those represented by the North Atlantic Oscillation (NAO) index and the Westerly Index (WI) have been widely proven as reliable proxies of drought trends. Here, we used the Standardized Precipitation–Evapotranspiration Index (SPEI), as a reliable indicator of drought, to investigate the drought sensitivity of tree-ring width data (TRW) from several long-lived tree species (Abies borisii-regis, Abies cilicica, Abies pinsapo, Cedrus atlantica, Cedrus libanii, Pinus nigra, Pinus heldreichii). NAO and WI relations with TRW were also investigated in order to identify potential non-stationary responses among those drought proxies. Our temporal and spatial analyses support contrasting Mediterranean dipole patterns regarding the drought sensitivity of tree growth for each tree species. The spatial assessment of NAO and WI relationships regarding SPEI and TRW showed on average stronger correlations westward with non-stationary correlations between annual WI index and TRW in all species. The results indicate that the drought variability and the inferred drought-sensitive trees species (e.g., C. atlantica) are related to the NAO and the WI, showing that TRW is a feasible proxy to long-term reconstructions of Westerly Index (WI) variability in the Western Mediterranean region. Spatial variability of drought severity suggests a complex association between NAO and WI, likely modulated by an east–west Mediterranean climate dipole.

scholarly journals Exploring Combined Influences of Seasonal East Atlantic (EA) and North Atlantic Oscillation (Nao) on the Temperature-Precipitation Relationship in the Iberian Peninsula

2021 ◽  
Author(s):  
Fernando S. Rodrigo
Keyword(s):  
North Atlantic Oscillation ◽  
Iberian Peninsula ◽  
North Atlantic ◽  
Negative Relationship ◽  
Correlation Coefficients ◽  
East Atlantic ◽  
Teleconnection Patterns ◽  
The North ◽  
Spatial Coverage ◽  
The North Atlantic Oscillation

The combined influence of the North Atlantic Oscillation (NAO) and the East Atlantic (EA) patterns on the covariability of temperatures and precipitation in 35 stations of the Iberian Peninsula during the period 1950-2019 is analysed in this work. Four EA-NAO composites were defined from teleconnection patterns positive and negative phases: EA+NAO+, EA+NAO-, EA-NAO+, and EA-NAO-. Daily data of maximum and minimum temperature were used to obtain seasonal means (TX, and TN, respectively), and the covariability of these variables with accumulated seasonal rainfall (R) was studied comparing results obtained for different NAO and EA composites. Main results indicate slight differences in the spatial coverage of correlation coefficients between R and temperature variables, except in spring when the generalized negative relationship between R and TX under EA+NAO+ and EA-NAO- disappears under EA-NAO+ and EA+NAO- composites. This result may be useful to interpret and discuss historical reconstructions of Iberian climate.

scholarly journals North Atlantic Oscillation affects dolphinfish as target and bycatch species in fisheries from the western Mediterranean Sea

2019 ◽  
Vol 6 ◽  
Author(s):  
Jose Báez ◽  
Juan Camiñas ◽  
Pilar Hernández ◽  
Marcelo Vasconcellos ◽  
Salvador García-Barcelona ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
Mediterranean Sea ◽  
North Atlantic ◽  
Western Mediterranean ◽  
Western Mediterranean Sea

Long-term predictability of winter teleconnection indices and their relationship to seasonal temperature extremes in Europe

2021 ◽  
Author(s):  
Nina Schuhen ◽  
Nathalie Schaller ◽  
Hannah C. Bloomfield ◽  
David J. Brayshaw ◽  
Jana Sillmann ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Surface Temperature ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Decadal Variability ◽  
Environmental Research ◽  
Seasonal Temperature ◽  
East Atlantic ◽  
Teleconnection Patterns

&lt;p&gt;European winter weather is dominated by several low-frequency teleconnection patterns, the main ones being the North Atlantic Oscillation (NAO), East Atlantic, East Atlantic/Western Russia and Scandinavian patterns. Through predicting these patterns, skillful forecasts of weather parameters like surface temperature can be generated, which in turn are used in a variety of applications (e.g., predictions of energy demand). A previous study (Weisheimer et.al., 2017) found that the NAO was subject to decadal variability during the twentieth century, affecting its long-term predictability. During recent decades, predictions for the NAO index have shown considerable skill, but this is likely to change during future periods of reduced predictability.&lt;/p&gt;&lt;p&gt;We analyze the century-long ERA-20C reanalysis and ASF-20C seasonal hindcast datasets to find if the other main teleconnection patterns also experience fluctuations in predictability, with potential implications for future skill and development of seasonal forecasting models. By linking the teleconnections to extreme cold and heat wave indices (Russo et al., 2015), we highlight the impact of these large-scale patterns on seasonal surface temperature in Europe during two periods of interest in the middle and end of the century. Our study shows that even though the predictability of the teleconnection patterns themselves fluctuates on a decadal scale, the links to winter surface temperatures are not significantly affected. However, the ability of the seasonal hindcasts to reproduce these patterns is quite limited.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Russo, S., Sillmann, J., &amp; Fischer, E. M. (2015). Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environmental Research Letters, 10(12), 124003. doi: 10.1088/1748-9326/10/12/124003&lt;/p&gt;&lt;p&gt;Weisheimer, A., Schaller, N., O&amp;#8217;Reilly, C., MacLeod, D. A., &amp; Palmer, T. (2017). Atmospheric seasonal forecasts of the twentieth century:&amp;#160; multi-decadal variability in predictive skill of the winter North Atlantic Oscillation (NAO) and their potential value for extreme event attribution. Quarterly Journal of the Royal Meteorological Society, 143(703), 917-926. doi: 10.1002/qj.29&lt;/p&gt;

scholarly journals Cyclones causing wind storms in the Mediterranean: characteristics, trends and links to large-scale patterns

2010 ◽  
Vol 10 (7) ◽  
pp. 1379-1391 ◽  
Author(s):  
K. M. Nissen ◽  
G. C. Leckebusch ◽  
J. G. Pinto ◽  
D. Renggli ◽  
S. Ulbrich ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Positive Phase ◽  
East Atlantic ◽  
The North ◽  
The North Atlantic ◽  
Wind Storms ◽  
The Mediterranean ◽  
Wind Events ◽  
The North Atlantic Oscillation

Abstract. A climatology of cyclones with a focus on their relation to wind storm tracks in the Mediterranean region (MR) is presented. Trends in the frequency of cyclones and wind storms, as well as variations associated with the North Atlantic Oscillation (NAO), the East Atlantic/West Russian (EAWR) and the Scandinavian variability pattern (SCAND) are discussed. The study is based on the ERA40 reanalysis dataset. Wind storm tracks are identified by tracking clusters of adjacent grid boxes characterised by extremely high local wind speeds. The wind track is assigned to a cyclone track independently identified with an objective scheme. Areas with high wind activity – quantified by extreme wind tracks – are typically located south of the Golf of Genoa, south of Cyprus, southeast of Sicily and west of the Iberian Peninsula. About 69% of the wind storms are caused by cyclones located in the Mediterranean region, while the remaining 31% can be attributed to North Atlantic or Northern European cyclones. The North Atlantic Oscillation, the East Atlantic/West Russian pattern and the Scandinavian pattern all influence the amount and spatial distribution of wind inducing cyclones and wind events in the MR. The strongest signals exist for the NAO and the EAWR pattern, which are both associated with an increase in the number of organised strong wind events in the eastern MR during their positive phase. On the other hand, the storm numbers decrease over the western MR for the positive phase of the NAO and over the central MR during the positive phase of the EAWR pattern. The positive phase of the Scandinavian pattern is associated with a decrease in the number of winter wind storms over most of the MR. A third of the trends in the number of wind storms and wind producing cyclones during the winter season of the ERA40 period may be attributed to the variability of the North Atlantic Oscillation.

North Atlantic oscillation affects the physical condition of migrating bullet tuna Auxis rochei (Risso, 1810) from the Western Mediterranean Sea

2017 ◽  
Vol 194 ◽  
pp. 84-88 ◽  
Author(s):  
Pedro Muñoz-Expósito ◽  
David Macías ◽  
José María Ortíz de Urbina ◽  
Salvador García-Barcelona ◽  
María José Gómez ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
Mediterranean Sea ◽  
North Atlantic ◽  
Physical Condition ◽  
Western Mediterranean ◽  
Western Mediterranean Sea
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