Person: Barriopedro Cepero, David
Universidad Complutense de Madrid
Faculty / Institute
Física de la Tierra y Astrofísica
Física de la Tierra
Now showing 1 - 10 of 68
PublicationAuthor Correction: Increasing heat and rainfall extremes now far outside the historical climate(Nature Portfolio, 2021-10-20) Barriopedro Cepero, DavidThe original version of this Article contained two typographic errors in the subsection 'Precipitation analysis' under 'Methods'. The fifth sentence contained a typo and originally read ‘To quantify how much the observed number of rainfall-records (R_(anom)) deviates…’. The correct version reads ‘To quantify how much the observed number of rainfall-records (R_(obs)) deviates…’. The sixth sentence incorrectly omitted the authors of ref 13 and originally read ‘…using the shuffling method as described in detail in^(13).’ The correct version reads ‘…using the shuffling method as described in detail by Lehmann et al.^(13).’ PublicationChanges in polar stratospheric temperature climatology in relation to stratospheric sudden warming occurrence(American Geophysical Union, 2012-11-22) Barriopedro Cepero, David; Gomez Escolar, M.; Fueglistaler, S.; Calvo Fernández, NataliaStratospheric Sudden Warmings (SSWs) strongly affect the polar stratosphere during winter months mainly in the Northern Hemisphere. The intraseasonal distribution and type of SSWs for the 1958-1979 and 1979-2002 periods in ERA-40 and NCEP-NCAR reanalyses reveal differences. In the pre-satellite era, most events occur in January and are vortex splits. In the post-satellite era, the distribution is bimodal (peaking in December and February), and shows more displacement events. The difference in the seasonal distribution of SSWs leads to changes in the climatological state of stratospheric temperatures, with differences up to 5.9 K at 10 hPa and 3.6 K at 20 hPa in February between pre- and post-1979 periods. We find that the temperature evolution at 20 hPa is in better qualitative agreement with theoretical expectations than at 10 hPa. Hence, 10 hPa may be affected more strongly by artifacts related with satellite data assimilation, which have, however, limited impact on identification of SSWs. PublicationLarge-scale temperature response to external forcing in simulations and reconstructions of the last millennium(Copernicus Gesellschaft MBH, 2013-02-14) Fernández Donado, Laura; Barriopedro Cepero, David; González Rouco, J. Fidel; García Bustamante, E.; Raible, C. C.; Ammann, C. M.; Lorenz, S. J.; Jungclaus, J. H.; Luterbacher, J.; Phipps, S. J.; Servonnat, J.; Swingedouw, D.; Tett, S. F. B.; Wagner, S.; Yiou, P.; Zorita, E.Understanding natural climate variability and its driving factors is crucial to assessing future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleo-climate model simulations is key to gaining insights into the relative roles of internal versus forced variability. A review of the state of modelling of the climate of the last millennium prior to the CMIP5-PMIP3 (Coupled Model Intercomparison Project Phase 5-Paleoclimate Modelling Intercomparison Project Phase 3) coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition from the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions. Thus, either internal variability is a possible major player in shaping temperature changes through the millennium or the model simulations have problems realistically representing the response pattern to external forcing. A last millennium transient climate response (LMTCR) is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed LMTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change. PublicationA 3-year study of cloud-to-ground lightning flash characteristics of Mesoscale convective systems over the Western Mediterranean Sea(Elsevier Science INC, 2006-02) García Herrera, Ricardo; Barriopedro Cepero, David; Correoso, Juan Francisco; Hernández Martín, Emiliano; Paredes, DanielIn this paper cloud-to-ground (CG) lightning flashes of 33 Mesoscale Convective Systems (MCSs) over the Western Mediterranean area are analyzed. Mean values of 22% for the positive CG ratio, 1.1 (2.4) for positive (negative) CG multiplicity, 17 kA (22.6 kA) of peak current for the positive (negative) CG flashes and a mean flash rate of around 13 min(-1) are obtained. The percentage of positive CGs and the multiplicity of negative CG are higher, while the mean peak currents are lower than in previous studies on MCSs. A more detailed case analysis reveals that there are great differences among the CG characteristics of MCSs. The life cycle of CG lightning associated with MCSs is also analyzed. The growing stages of MCSs are characterised by high CG lightning activity. The positive CG flash rate generally reaches a maximum before the negative CG flash rate does. In both cases the peak is recorded before or when MCSs show the largest area. Maximum flash rate and densities coincide with the area where the MCS shows the minimum cloud-top temperatures and therefore shows highest vertical development. PublicationClimatology and characteristics of stratospheric sudden warmings in the Whole Atmosphere Community Climate(American Geophysical Union, 2012-02-25) Torre, Laura de la; Garcial, Rolando R.; Barriopedro Cepero, David; Chandran, AmalMajor stratospheric sudden warmings (SSW) occurring during Northern Hemisphere winter were identified in four runs of the Whole Atmosphere Community Climate Model (WACCM). Their characteristics are compared to those found by other authors using reanalysis data. The comparison shows that the frequency of occurrence of major SSW in the model is very similar to that found in reanalysis data, as is the occurrence of vortex splitting and displacement events. The main difference with respect to observations is that the modeled SSW are relatively longer lasting. WACCM simulates quite accurately some dynamical features associated with major SSW, despite the presence of outlier cases; however, the recently reported relationship between regional blocking and the type of SSW is only partially reproduced by WACCM. In general, the observed climatological and dynamical signatures of displacement SSW tend to be better reproduced by the model than those associated with splitting SSW. We also find that SSW in the model are often associated with an elevated polar cap stratopause, in agreement with recent observations. However, the simulations also show that there is not in general a close correspondence between major SSW and elevated polar cap stratopause events. PublicationNorth Atlantic oscillation influence and weather types associated with winter total and extreme precipitation events in Spain(Elsevier Science INC, 2009-12) Queralt, S.; Barriopedro Cepero, David; Hernández, E.; Gallego, D.; Ribera, P.; Casanova, C.An analysis of winter intensity and frequency of precipitation is presented, based on 102 daily precipitation stations over Spain and the Balearic Islands for the 1997-2006 decade. Precipitation stations have been merged in the eight different regions which compose the analyzed area by the use of an EOF analysis. NAO influence on the intensity and frequency of precipitation of each region is described in terms of mean precipitation, mean rain frequency, the number of extreme events, changes in the precipitation distribution and the prevalent synoptic configuration. Results indicate a non-stationary response; NAO signal being more evident in mid-late winter. Strong regional differences in the response to NAO are also found, which vary according to the specific character of the precipitation under analysis. Thus, NAO exerts a clear effect on the intensity of total and extreme precipitation rates in northern and westernmost Spanish regions, whereas the frequency of precipitation is clearly affected by NAO in central and southwestern areas. While the correlation between NAO and precipitation is negative for most of the analyzed area, two regions reveal positive responses to NAO in total precipitation occurrence and intensity for specific months. Further analyses reveal asymmetric responses to opposite phases of NAO in the precipitation distributions of some regions. The complex regional relationship between NAO and precipitation is also revealed through the modulation of the former in the preferred Circulation Weather Types associated to precipitation in each region. This spatially non-homogeneous NAO signal stresses the need of caution when employing Iberian precipitation as a proxy for NAO. PublicationThe outstanding 2004/05 drought in the Iberian Peninsula: associated atmospheric circulation(American Meteorological Society, 2007-06) García Herrera, Ricardo; Hernández Martín, Emiliano; Barriopedro Cepero, David; Trigo, Ricardo M.; Paredes, Daniel; Trigo, Isabel Franco; Mendes, Manuel A.The 2004/05 hydrological year (October 2004 to September 2005) was characterized by intense dry conditions affecting most of western Europe (35 degrees-55 degrees N and 10 degrees W-10 degrees E). In Iberia the drought affected every month of this period, with the southern half of Iberia receiving roughly 40% of the usual precipitation by June 2005. Moreover, this episode stands as the driest event in the last 140 yr, producing major socioeconomic impacts particularly due to the large decrease in hydroelectricity and agricultural production in both Iberian countries (Portugal and Spain). To assess the atmospheric submonthly circulation associated with this drought an Eulerian [weather types (WTs)] and a Lagrangean (objective storm tracks) analysis were combined. There was a dramatic drop in "wet" WT frequency during winter, with less than 50% of the normal value, and a corresponding increase of "dry" WTs. The storm-track analysis reveals an impressive northward displacement of cyclone trajectories in the North Atlantic sector in winter months, resulting in an almost complete absence of cyclones crossing Iberia and western Europe. At the monthly scale, the intense drought in Iberia was due to a combination of different physical mechanisms. First, the scarce precipitation observed between November 2004 and January 2005 was associated with positive North Atlantic Oscillation (NAO) indexes for these months. In February, the East Atlantic (EA) pattern seems to be the main driver. In March neither the negative NAO (-1.8) nor the positive EA (1.1) are capable of explaining the large negative precipitation anomalies. However, it is shown that during March 2005, an intense and anomalous blocking was displaced southward of its usual location, inhibiting the occurrence of precipitation over Iberia and leading to a negative NAO index anomalously associated with low precipitation records. PublicationWitnessing North Atlantic westerlies variability from ships' logbooks (1685-2008)(Springer, 2014-08) Barriopedro Cepero, David; Gallego, David; Álvarez Castro, M. Carmen; García Herrera, Ricardo; Wheeler, Dennis; Peña Ortiz, Cristina; Barbosa, Susana M.A monthly index based on the persistence of the westerly winds over the English Chanel is constructed for 1685–2008 using daily data from ships’ logbooks and comprehensive marine meteorological datasets. The socalled Westerly Index (WI) provides the longest instrumental record of atmospheric circulation currently available. Anomalous WI values are associated with spatially coherent climatic signals in temperature and precipitation over large areas of Europe, which are stronger for precipitation than for temperature and in winter and summer than in transitional seasons. Overall, the WI series accord with the known European climatic history, and reveal that the frequency of the westerlies in the eastern Atlantic during the twentieth century and the Late Maunder Minimum was not exceptional in the context of the last three centuries. It is shown that the WI provides additional and complementary information to the North Atlantic Oscillation (NAO) indices. The analysis of WI series during the industrial era indicates an overall good agreement with the winter and high-summer NAO, with the exception of several multidecadal periods of weakened correlation. These decoupled periods between the frequency and the intensity of the zonal flow are interpreted on the basis of several sources of non-stationarity affecting the centres of the variability of the North Atlantic and their teleconnections. Comparisons with NAO reconstructions and long instrumental indices extending back to the seventeenth century suggest that similar situations have occurred in the past, which call for caution when reconstructing the past atmospheric circulation from climatic proxies. The robustness and extension of its climatic signal, the length of the series and its instrumental nature make the WI an excellent benchmark for proxy calibration in Europe and Greenland. PublicationA discussion of the links between solar variability and high-storm-surge events in Venice(American Geophysical Union, 2010-07-01) Barriopedro Cepero, David; García Herrera, Ricardo; Lionello, Piero; Pino, CosimoThis study explores the long-term frequency variability of high-surge events (HSEs) in the North Adriatic, the so-called acqua alta, which, particularly during autumn, cause flooding of the historical city center of Venice. The period 1948-2008, when hourly observations of sea level are available, is considered. The frequency of HSEs is correlated with the 11 year solar cycle, solar maxima being associated with a significant increase in the October-November-December HSE frequency. The seasonal geopotential height pattern at 1000 hPa (storm surge pattern; SSP) associated with the increased frequency of HSEs is identified for the whole time period and found to be similar to the positive phase of the main variability mode of the regional atmospheric circulation (empirical orthogonal function 1; EOF1). However, further analysis indicates that solar activity modulates the spatial patterns of the atmospheric circulation (EOF) and the favorable conditions for HSE occurrence (SSP). Under solar maxima, the occurrence of HSEs is enhanced by the main mode of regional atmospheric variability, namely, a large-scale wave train pattern that is symptomatic of storm track paths over northern Europe. Solar minima reveal a substantially different and less robust SSP, consisting of a meridionally oriented dipole with a preferred southward path of storm track activity, which is not associated with any dominant mode of atmospheric variability during low-solar periods. It is concluded that solar activity plays an indirect role in the frequency of HSEs by modulating the spatial patterns of the main modes of atmospheric regional variability, the favorable patterns for HSE occurrence, and their mutual relationships, so that constructive interaction between them is enhanced during solar maxima and inhibited in solar minima. PublicationThe hot summer of 2010: redrawing the temperature record map of Europe(American Association Advancement Science, 2011-04-08) Barriopedro Cepero, David; Fischer, Erich; Luterbacher, Jürg; Trigo, Ricardo M.; García Herrera, RicardoThe summer of 2010 was exceptionally warm in eastern Europe and large parts of Russia. We provide evidence that the anomalous 2010 warmth that caused adverse impacts exceeded the amplitude and spatial extent of the previous hottest summer of 2003. "Mega-heatwaves" such as the 2003 and 2010 events likely broke the 500-year-long seasonal temperature records over approximately 50% of Europe. According to regional multi-model experiments, the probability of a summer experiencing mega-heatwaves will increase by a factor of 5 to 10 within the next 40 years. However, the magnitude of the 2010 event was so extreme that despite this increase, the likelihood of an analog over the same region remains fairly low until the second half of the 21st century.