The environments of significant convective events in the western Mediterranean

The environmental characteristics associated with 313 significant convective events in the western Mediterranean are investigated using radiosonde ascents made in Mallorca (Spain). The events are separated into five groups, based on the observed event (hail, heavy rain, ‘‘dry’’ storms, storms with heavy rain, and tornadoes). Classic stability indices, as well as values of convective available potential energy and helicity, are considered for each group. These traditional convective indices appear not to provide good guidance for discriminating environments associated with each group of events. In order to classify the environments, each sounding is defined by means of 34 variables that describe the thermal and humidity vertical structure, instability, precipitable water, and helicity. A cluster analysis shows that four different vertical structures appear. Each kind of event shows preference for the environments defined by a cluster. A simple method is presented for sounding classification using the four categories obtained from the cluster analysis. The method looks for the best correlation between a particular sounding and those defined by each cluster.This work has been partially sponsored by the EC under Contract EV5V-CT94-0442 and CICYT Grants AMB95-1136-CE

A deep cyclone of African origin over the Western Mediterranean: Diagnosis and numerical simulation

From 19 to 22 December 1979, a deep cyclone evolved over the Western Mediterranean. Gusty winds of more than 30 m/s, as well as a strong pressure decrease to about 990hPa were recorded in Palma de Mallorca (Balearic Islands, Spain). ECMWF analyses are used for a diagnosis and numerical study of the case. Sensitivity experiments using the HIRLAM model are performed to assess the role of the surface sensible heat flux, latent release and orography on the genesis and evolution of the cyclone. At synoptic scale, the situation is governed by the instability of an upper-level short wave. The cyclone developed within a notable baroclinic environment, which resulted from a cold advection from the northwest towards North Africa. The baroclinicity at first stages of the cyclogenesis is quantified by means of the Eady model. At latter stages, the evolution of the potential vorticity structures at high levels reveals a wide tropopause fold over the cyclone, as well as the presence of a strong anomaly associated with the low-level system. Sensitivity experiments reveal a notable cyclogenetic role of the latent heat release throughout the atmosphere in the deepening of the low, whereas no significant effect of the surface sensible heat flux is obtained for the simulation interval. On the other hand, an unusual cyclolytic role can be attributed to the northern ranges of the Mediterranean basin. Effectively, the low enlargement and deepening is constrained by a >wall effect>, which is a consequence of the interaction of the cyclonic flow and those northern mountainous systems.Peer Reviewe

Clasificación automática de sondeos. Situaciones de mal tiempo en el Mediterráneo occidental

Ponencia presentada en: IV Simposio Nacional de Predicción del Instituto Nacional de Meteorología, celebrado en 1999 en MadridEn este trabajo se analizan 313 sondeos de Palma simultáneos a cinco tipos de fenómenos convectivos: granizo, tormenta con y sin lluvia, lluvia únicamente y tornados. Se realiza un análisis de «clusters» a los sondeos definidos por 34 variables (estructuras térmica y de humedad, CAPE, helicidad y agua precipitable) y aparecen cuatro tipos de ambientes. Un análisis de componentes principales sobre la misma base de datos muestra que un nuevo «clustering» sobre seis variables (76% de la varianza) da resultados semejantes. El objetivo, la clasificación de sondeos, buscará la mayor correlación entre éstos y el representante de cada «cluster»

Simulación numérica de la brisa en Mallorca

Ponencia presentada en: II Simposio Nacional de Predictores, celebrado en 1990 en Madrid los días 20-22 de noviembr

PREGRIDBAL 1.0: towards a high-resolution rainfall atlas for the Balearic Islands (1950–2009)

This work presents a catalog of daily precipitation fields in the Balearic Islands created with data from AEMET (State Meteorological Agency) assistant observations, including records from 1912. The original digital daily data file has been interpolated onto a regular 100 m-resolution grid (namely PREGRIDBAL), defined with the aim of becoming a valid standard for future methodological improvements and catalog upgrades. Daily precipitation amounts on each grid point are calculated using an analysis method based on ordinary kriging, using the daily anomaly with respect to the annual mean for all available observations each day. Due to quality concerns, the time span for products derived from the catalog is limited to the 1950–2009 period, when the number of operating stations reached 200.The study has partially been funded by the “Conselleria d’Educació, Cultura i Universitats del Govern de les Illes Balears” and FEDER fund (project 7/2011 competitive research groups) and Ministry of Science and Innovation (projects CGL2011-24458 and CGL2014-52199-R)

Tornadoes over complex terrain: an analysis of the 28th August 1999 tornadic event in eastern Spain

On 28 August 1999, a tornadic storm developed during the afternoon over the Gudar range, near the border between Teruel and Castellón provinces (Sistema Ibérico, eastern Spain). The area has a characteristic complex terrain with peaks up to 2000 m. At least one tornado developed, which attained F3 intensity, producing severe damage in the forest that covers the mountains. The region is well known as a summer convective storm nest and, not surprisingly, a range in the Sistema Iberico is called Sierra del Rayo (lightning range).This work has been partially supported by the CICYT CLI99-0269 and CICYT REN2002-03482 grants

Daily rainfall variability in the Spanish Mediterranean area

Ponencias presentadas en: 2nd European Conference on Applied Climatology (ECAC) celebrada en Viena del 19 al 23 de octubre de 2018

Catalogation of cyclones in the Western Mediterranean

Ponencia presentada en: INM/WMO International Symposium on Cyclones and Hazardous Weather in the Mediterranean celebrado en Palma de Mallorca, del 14 al 17 de abril de 1997

Tormenta mediterránea de 15 de noviembre de 1985: mecanismo de disparo

[ES]Los mecanismos de focalización y disparo que condujeron al episodio de intensa lluvia covectiva ocurrido en las Baleares el 15 de noviembre de 1985 (Ramis et al., 1986) se identifican por medio del diagnóstico obje tivo del "forzamiento" dinámico cuasi-geostrófico.[EN]Focusing and triggering mechanisms producing the heavy convective precipitation event occurred in the Balearics on November, 15th, 1985 (Ramis et al., 1986) are identified by means of objective diagnosis of the quasi-geostrophic dynamical forcing

Extension of summer climatic conditions into spring in the Western Mediterranean area

From a local point of view, in May/June there is an important and positive 2 m temperature trend at Palma (Mallorca), which is simultaneous and highly correlated with a strong increase in the 500 hPa geopotential height. The present study analyses this fact as well as the observed tendencies in a wider seasonal and geographical context. We confirm the particularly high correlation between 2 m temperature and 500 hPa geopotential during the warm months as opposed to the much weaker correlation in winter. This suggests that mechanisms for thermal changes act differently throughout the year in this region. Besides the direct radiative effect, warm season near-surface temperatures are linked to the presence of deep anticyclones, which effectively determine the northern edge of the Hadley cell. Accordingly, the strong warming trend in the area of Palma during the warm months of the year is purportedly related to the poleward extension of the Hadley cell.This work was partially supported by EXTREMO (CGL2014-52199-R) project, funded by the Spanish Ministry of the Economy and Competitiveness, with partial contribution from FEDER funds