scholarly journals Torrential rainfall in northeast of the Iberian Peninsula: synoptic patterns and WeMO influence

2008 ◽  
Vol 2 (1) ◽  
pp. 99-105 ◽  
Author(s):  
J. Martin-Vide ◽  
A. Sanchez-Lorenzo ◽  
J. A. Lopez-Bustins ◽  
M. J. Cordobilla ◽  
A. Garcia-Manuel ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Principal Component ◽  
Western Mediterranean ◽  
Atmospheric Conditions ◽  
Synoptic Patterns ◽  
Daily Data ◽  
Circulation Patterns ◽  
Torrential Rainfall ◽  
Index Value ◽  
Mediterranean Oscillation

Abstract. This study presents a catalogue of synoptic patterns of torrential rainfall in northeast of the Iberian Peninsula (IP). These circulation patterns were obtained by applying a T-mode Principal Component Analysis (PCA) to a daily data grid (NCEP/NCAR reanalysis) at sea level pressure (SLP). The analysis made use of 304 days which recorded >100 mm in one or more stations in provinces of Barcelona, Girona and Tarragona (coastland area of Catalonia) throughout the 1950–2005 period. The catalogue comprises 7 circulation patterns showing a great variety of atmospheric conditions and seasonal or monthly distribution. Likewise, we computed the mean index value of the Western Mediterranean Oscillation index (WeMOi) for the synoptic patterns obtained by averaging all days grouped in each pattern. The results showed a clear association between the negative values of this teleconnection index and torrential rainfall in northeast of the IP. We therefore put forward the WeMO as an essential tool for forecasting heavy rainfall in northeast of Spain.

Torrential rainfall prediction: WeMOTool

2020 ◽  
Author(s):  
Laia Arbiol-Roca
Keyword(s):  
Iberian Peninsula ◽  
Surface Pressure ◽  
Significant Relationship ◽  
Western Mediterranean ◽  
Pressure Data ◽  
Predictive Tool ◽  
Rainfall Prediction ◽  
Gfs Model ◽  
Torrential Rainfall ◽  
Mediterranean Oscillation

<p>The Western Mediterranean Oscillation index (WeMOi) presents a statistically significant relationship with the pluviometric totals of the eastern façade of the Iberian Peninsula. Use of the WeMOi at daily resolution has proven to constitute a useful tool for helping to predict torrential rainfall episodes in the east of the peninsula. The present research attempts to determinate which atmospherics circulations defines the WeMOi phases. Also, the WeMOi research has focused on the prediction of it in order to configure itself as a predictive tool, the WeMOTool, for torrential rains associated, especially during the autumn months. The calculation of this index is made using the surface pressure data of the GFS model and is updated with the model outputs at 00h and 12h and up to 144h.</p>

scholarly journals Intra-annual variability of the Western Mediterranean Oscillation (WeMO) and occurrence of extreme torrential rainfall in Catalonia (NE Iberia)

2019 ◽  
Author(s):  
Joan Albert Lopez-Bustins ◽  
Laia Arbiol-Roca ◽  
Javier Martin-Vide ◽  
Antoni Barrera-Escoda ◽  
Marc Prohom
Keyword(s):  
Climate Change ◽  
Mediterranean Region ◽  
Western Mediterranean ◽  
Sensitive Area ◽  
Weather Extremes ◽  
Late Autumn ◽  
Annual Variability ◽  
Torrential Rainfall ◽  
Mediterranean Oscillation

Abstract. In previous studies the Western Mediterranean Oscillation index (WeMOi) at daily resolution has proven to constitute an effective tool for analysing the occurrence of episodes of torrential rainfall over eastern Spain. The Western Mediterranean region is therefore a very sensitive area, since climate change can enhance these weather extremes. In the present study we selected the extreme torrential episodes (≥ 200 mm in 24 hours) that took place in Catalonia (NE Iberia) during the 1951–2016 study period (66 years). We computed daily WeMOi values and constructed WeMOi calendars. Our principal results reveal the occurrence of 50 episodes (0.8 cases per year), mainly concentrated in the autumn months. We inferred a threshold of WeMOi ≤ −2 to define an extreme negative WeMO phase at daily resolution. Most of the 50 episodes (60 %) in the study area occurred on days presenting an extreme negative WeMOi value. Specifically, the most negative WeMOi values are detected in autumn, during the second 10-day period of October (11th–20th), coinciding with the highest frequency of extreme torrential events. On comparing the subperiods, we observed a statistically significant decrease in WeMOi values in all months, particularly in late October, and in November and December. No changes in the frequency of these extreme torrential episodes were observed between both subperiods; in contrast, a displacement of the episodes is detected from early to late autumn.

scholarly journals Synoptic aspects associated with pervasive dust storms in the southwestern regions of Iran

Időjárás ◽  
2021 ◽  
Vol 125 (1) ◽  
pp. 151-166
Author(s):  
Mahdi Sedaghat ◽  
Hasan Hajimohammadi ◽  
Vahid Shafaie
Keyword(s):  
Principal Component ◽  
Dust Storms ◽  
Reanalysis Dataset ◽  
Mean Values ◽  
Synoptic Patterns ◽  
The North ◽  
Daily Data ◽  
The Matrix ◽  
Dominant Structure ◽  
Map Analysis

Dust storm is a natural hazardous phenomenon that affects arid and semi-arid regions of the world the same as Iran. The present research aims to investigate the formation of synoptic patterns of pervasive dust storms (PDSs) in the southwestern regions of Iran. For this purpose, daily data of visibility less than 1000m in 16 synoptic stations (Ilam and Khuzestan provinces) were reviewed during 2004–2017, and 59 PDSs with more than 2 days of duration (overlapped: 70% of the region) were extracted. In practice, mid-level atmospheric data (500, 700, 850 hPa, and sea level pressure (SLP)) with 2.5*2.5 degree resolution (domain: 0-80°E and 10-70°N) were obtained from NCEP/NCAR reanalysis dataset, and the matrix 825*59 of 500 hPa data was performed. Principal component analysis (PCA) with S-mod, were used for extracting synoptic patterns that make PDSs. PCA showed that the first four components ensured more than 86.45% of the data variance. PDSs classification based on output components showed that the patterns had seasonal structures. Synoptically, the north wind blowing in the first pattern is the most dominant structure in the formation of PDSs in the Middle East. The second and third patterns showed postfrontal structures. The fourth pattern with prefrontal structure was the reason for PDSs in the cold seasons of the year. From the four final patterns, the first three patterns showed the dominance of the Persian trough in the SLP maps. Mean values map analysis of the aerosol optical depth suggests that each of the most consistent synoptic patterns stimulates special dust centers.

scholarly journals Snowfall in the Northwest Iberian Peninsula: Synoptic Circulation Patterns and Their Influence on Snow Day Trends

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Andrés Merino ◽  
Sergio Fernández ◽  
Lucía Hermida ◽  
Laura López ◽  
José Luis Sánchez ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Principal Component ◽  
Kendall Test ◽  
Central Plateau ◽  
Mountain Ranges ◽  
Transportation Risk ◽  
Castilla Y Leon ◽  
Circulation Patterns ◽  
Synoptic Circulation

In recent decades, a decrease in snowfall attributed to the effects of global warming (among other causes) has become evident. However, it is reasonable to investigate meteorological causes for such decrease, by analyzing changes in synoptic scale patterns. On the Iberian Peninsula, the Castilla y León region in the northwest consists of a central plateau surrounded by mountain ranges. This creates snowfalls that are considered both an important water resource and a transportation risk. In this work, we develop a classification of synoptic situations that produced important snowfalls at observation stations in the major cities of Castilla y León from 1960 to 2011. We used principal component analysis (PCA) and cluster techniques to define four synoptic patterns conducive to snowfall in the region. Once we confirmed homogeneity of the series and serial correlation of the snowfallday records at the stations from 1960 to 2011, we carried out a Mann-Kendall test. The results show a negative trend at most stations, so there are a decreased number of snowfall days. Finally, variations in these meteorological variables were related to changes in the frequencies of snow events belonging to each synoptic pattern favorable for snowfall production at the observatory locations.

The Western Mediterranean Oscillation and rainfall in the Iberian Peninsula

2006 ◽  
Vol 26 (11) ◽  
pp. 1455-1475 ◽  
Author(s):  
Javier Martin-Vide ◽  
Joan-Albert Lopez-Bustins
Keyword(s):  
Iberian Peninsula ◽  
Western Mediterranean ◽  
Mediterranean Oscillation

scholarly journals Seasonal variability of atmospheric patterns leading to air pollution in the metropolis of Tehran

2019 ◽  
Author(s):  
Sakineh Khansalari ◽  
Abbas Ranjbar Saadatabadi ◽  
Leila Mohammadian Mohammadi ◽  
Majid Gozalkhoo
Keyword(s):  
Air Pollution ◽  
Airborne Particulate Matter ◽  
Principal Component ◽  
Atmospheric Conditions ◽  
Synoptic Patterns ◽  
Different Seasons ◽  
Pm2.5 And Pm10 ◽  
The City ◽  
Harmful Effects ◽  
Height Data

Introduction: Air pollution, due to its harmful effects especially on human health, is one of the major problems of industrial cities and metropolises, including Tehran. Therefore, recognizing the atmospheric conditions that lead to the accumulation of the pollutants can help decision-maker organizations. Materials and methods: In this study, based on the intensity and persistency of the air pollution in the period of 1389-1397 and according to the season of its occurrence, 47 air pollution incidents in Tehran were identified and studied from synoptic perspective. Spatial (T-Mode) principal component analysis was applied to 500-hpa geopotential height data of these events to classify the synoptic patterns which make the city prone to intensification of pollution in different seasons. Results: The results indicate three different synoptic patterns leading to an increase in the potential of pollution of Tehran. In these patterns, the main pollutant is the airborne particulate matter (PM2.5 and PM10). Accordingly, the first pattern with percentage frequency of 62% occurs in the fall and winter. In this pattern, the presence of Siberian high pressure, along with the midtropospheric ridge is obvious. Two other patterns are active in the late spring and summer (related to Indian monsoon in the southeast of Iran) and spring and autumn (related to dynamic low-pressure in Iraq and the west of Iran), respectively. Conclusion: Classifying of the data of polluted days during recent eight years for Tehran results in three synoptic patterns related to different seasons. This information can help better managing of urban activities.

scholarly journals Synoptic Causes of Torrential Rainfall in the Balearic Islands (1941–2010)

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1035
Author(s):  
Miquel Grimalt-Gelabert ◽  
Gabriel Alomar-Garau ◽  
Javier Martin-Vide
Keyword(s):  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Eastern Coast ◽  
Weather Station ◽  
Atmospheric Conditions ◽  
Common Occurrence ◽  
Torrential Rain ◽  
Western Mediterranean Basin ◽  
Torrential Rainfall

This article determines the atmospheric situation for the 53 days where any weather station in the Balearic Islands detected torrential rain (equal to or above 200 mm in a single day) during the period 1941–2010. To do this, the synoptic charts for each day were analysed, classifying them in accordance with the types established by Martín Vide (1984) and, in addition, through the automatic synoptic classifications from Jenkinson and Collison (1977). The analysis results demonstrate the importance of cyclonic situations over the Western Mediterranean Basin linked to favourable altitude configurations (earlier presence of cut-off lows—DANA—or troughs). These atmospheric conditions contrast with those that predominate in nearby Mediterranean areas, such as the south-eastern coast of the Iberian Peninsula. Days with torrential rain on the Iberian coastline tend to coincide with easterly advections—a less common occurrence in the Balearics.

scholarly journals Synoptic causes of torrential rainfall in South-eastern Spain (1941–2017)

2020 ◽  
Author(s):  
J. Martín-Vide ◽  
M.C. Moreno-García ◽  
J.A. López-Bustins
Keyword(s):  
High Altitude ◽  
Surface Pressure ◽  
Western Mediterranean ◽  
Teleconnection Pattern ◽  
Weather Station ◽  
Synoptic Classification ◽  
South Eastern ◽  
Torrential Rainfall ◽  
Mediterranean Oscillation ◽  
Cold Core

The weather types of 68 dates with torrential rainfall (≥200 mm/day) recorded at any weather station in the provinces of Alicante or Murcia during the period between 1941 and 2017 were determined using the Martín-Vide’s 1984 manual synoptic classification. Other relevant synoptic characteristics, as well as the surface pressure, and the value of the Western Mediterranean Oscillation index (WeMOi) on which those dates fell were also considered. The results show the high percentage of the Advection from the East with DANA (isolated high-altitude depression) or ‘gota fría’ type, which is present in more than 50% of the events, followed by the Trough type at 500 hPa and the Dynamic or Cold-core Low type, in the torrential rainfalls of South-eastern Spain. Except for the latter type, the average air pressure is close to or higher than normal. The WeMOi was negative for all events, which is consistent with the nature of this teleconnection pattern.

Potential of Arabic documentary sources for reconstructing past climate in the western Mediterranean region from AD 680 to 1815

The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Yassin Meklach ◽  
Chantal Camenisch ◽  
Abderrahmane Merzouki ◽  
Ricardo Garcia Herrera
Keyword(s):  
Spatial Resolution ◽  
Mediterranean Region ◽  
Climate Extremes ◽  
Western Mediterranean ◽  
Historical Documents ◽  
Atmospheric Conditions ◽  
Documentary Sources ◽  
Drought Conditions ◽  
Temporal And Spatial ◽  
Climate Proxies

Archival records and historical documents offer direct observation of weather and atmospheric conditions and have the highest temporal and spatial resolution, and precise dating, of the available climate proxies. They also provide information about variables such as temperature, precipitation and climate extremes, as well as floods, droughts and storms. The present work studied Arab-Islamic documentary sources covering the western Mediterranean region (documents written by Arab-Islamic historians that narrate social, political and religious history) available for the period AD 680–1815. They mostly provide information on hydrometeorological events. In Iberia the most intense droughts were reported during AD 747–753, AD 814–822, AD 846–847, AD 867–874 and AD 914–915 and in the Maghreb AD 867–873, AD 898–915, AD 1104–1147, AD 1280–1340 and AD 1720–1815 had prevalent drought conditions. Intense rain episodes are also reported.

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