Inicio  /  Atmósfera  /  Vol: 26 Núm: 1 Par: 0 (2013)  /  Artículo
ARTÍCULO
TITULO

Determination of the Jenkinson and Collison?s weather types for the western Mediterranean basin over the 1948-2009 period. Temporal analysis

M. Grimalt    
M. Tomàs    
G. Alomar    
J. Martin-Vide    
M. C. Moreno-García    

Resumen

We determined the weather type, according to the Jenkinson and Collison procedure, of the 22 646 days in the 1948-2009 period for the western Mediterranean basin. The analysis is based upon the surface pressure values of the NCEP/NCAR reanalysis, for a grid of nine points with extreme vertices at 45º N, 5º W and 35º N, 15º E, which provides a broad synoptic catalogue for this region. We analyzed the trends of the types and their different groupings during the same period. The most frequent type is U (undetermined), with an annual average of approximately 100 days (99.4, 27.2%), followed by type A (anticyclone), with 75.5 days/ year (20.7%), and C (depression), with 67.8 days/year (18.6%). The high frequency of type U is due to the habitual pressure of baric fields with a low gradient over Mediterranean waters in the warm half of the year.According to their directions, the types from the west are the most frequent and those from the south, the least. The monthly regime of the most frequent types and groupings is quite regular; type C groups, as well as advective and cyclonic curvature groups, present summertime minima and maxima in the cold half of theyear, whereas the opposite occurs with types U and A. The main statistically significant annual trends in the 1948-2009 period involve a decrease in type A (?4.19 days/decade, that is, ?29.0%) and an increase in type U, the cyclonic types and those presenting an easterly component. On comparing the 31-yr sub-periods1948-1978 and 1979-2009, the tendencies of A and U were confirmed, and increases can generally be seen in the types presenting an easterly component and a decrease in those with a westerly component.The variation in type A ranged from 2490 days in the first sub-period to 2192 in the second one (p = 0.000), mainly concentrated in summer and autumn. This evident reduction of type A coincides, paradoxically, with an increase in the sea surface pressure variable (+0.31 hPa/decade) throughout the 62 years of analysis. The negative trend found in type A differs from the results of some studies. The different analysis periods, thedifferent scales or areas of study and the variety of methods used to determine the weather types can account for the fact that these results are discordant. Moreover, warming over the last few decades in the waters of the western Mediterranean basin, as well as the clearly cyclogenetic character of the gulfs of Lion and Genoa, might account for the decrease in type A and the increase in the cyclonic curvature types.

 Artículos similares

       
 
Darko Lovrec, Roland Kalb and Vito Tic    
Manufacturers of hydraulic fluids invest a lot of effort and resources in improving their physico-chemical properties, with the goal of getting as close as possible to the properties of an ideal hydraulic fluid. It should be non- flammable, environmental... ver más
Revista: Applied Sciences

 
Jifeng Zhu, Xiaohe Pan, Zheng Peng, Mengzhuo Liu, Jingqian Guo and Jun-Hong Cui    
The establishment of the Underwater Internet of Things (UIoT) and the realization of interconnection between heterogeneous underwater intelligent devices are urgent global challenges. Underwater acoustic networking is the most suitable technology to achi... ver más

 
Sooyoun Nam, Kidae Kim, Sujin Jang, Jaeuk Lee, Shinwoo Gi, Minseok Kim, Jin Kwan Kim and Sukwoo Kim    
Identifying potential sources of suspended sediment (SS) in headwater catchments is crucial for water quality management. To differentiate these potential SS sources, we investigated the distribution of two fallout radionuclides (FRNs), 137Cs and 210Pbex... ver más
Revista: Water

 
Linpei Zhai and Jae Eun Lee    
This study aimed to explore the differences in various aspects of community disaster resilience and how to enhance disaster resilience tailored to different community types. The evaluation results were validated using the flood event that occurred in Zhe... ver más
Revista: Water

 
Aravind Kolli, Qi Wei and Stephen A. Ramsey    
In this work, we explored computational methods for analyzing a color digital image of a wound and predicting (from the analyzed image) the number of days it will take for the wound to fully heal. We used a hybrid computational approach combining deep ne... ver más
Revista: Computation