Spanish Meteorological Agency AEMET

Madrid, Spain

Spanish Meteorological Agency AEMET

Madrid, Spain
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Tapiador F.J.,University of Castilla - La Mancha | Navarro A.,University of Castilla - La Mancha | Moreno R.,University of Castilla - La Mancha | Jimenez-Alcazar A.,University of Castilla - La Mancha | And 7 more authors.
Journal of Hydrometeorology | Year: 2017

Laser disdrometers measure the particle size distribution (PSD) of hydrometeors through a small cross-sectional (tens of square centimeters) surface. Such a limited area induces a sampling effect in the estimates of the PSD, which translates to error in the reflectivity-rain-rate (Z-R) relationship used for ground radar estimates of rainfall, estimates of kinetic energy of precipitation, and any other hydrometeorological application relying on particle size information. Here, the results of a dedicated experiment to estimate the extent of the effect of limited area sampling of rainfall are presented. Using 14 Parsivel, version 1 (Parsivel-1), disdrometers placed within 6 m2, it was found that the combined area of at least seven disdrometers is required for the estimates to start converging to a stable value. The results can be used to quantify the degree of over-/underestimation of precipitation parameters for a single instrument due to the limited collecting area effect. It has been found that a single disdrometer may underestimate instantaneous rain rate by 70%. © 2017 American Meteorological Society.

Santos C.,Spanish Meteorological Agency AEMET | Ghelli A.,ECMWF
Quarterly Journal of the Royal Meteorological Society | Year: 2012

It is common practice when assessing the skill of either deterministic or ensemble forecasts to consider the observations with no uncertainty. Observation uncertainty may be associated with different causes and the present paper discusses the uncertainty that derives from the mismatch between model-generated grid point precipitation and locally measured precipitation values. There have been many attempts to add uncertainty to the verification process; in the present paper the uncertainty is derived from the observed precipitation distribution within grid boxes of assigned resolution. The Brier skill score (BSS) and the area under relative operating characteristic curve skill score calculated utilizing the verification method which includes observational uncertainty (O-OP), are compared to analogous scores obtained from standard verification methods. The scores are calculated for two different forecasting systems: the European Centre for Medium-Range Weather Forecasts Ensemble Prediction System and the Spanish Meteorological Agency Short-Range Ensemble Prediction System. The results show that the resolution component of the BSS improves when using the O-OP method, i.e. forecast probabilities are distinguished from climatological probabilities and therefore the system has better skill. The reliability component, on the contrary, greatly degrades and this degradation is worse for lower precipitation thresholds. The results also show that the more asymmetric the precipitation distribution is within the grid box, the larger is the degradation of the reliability component. The overall BSS improves except for low thresholds. These results encourage further research into observation uncertainty and how it can be effectively accounted for in the verification of weather parameters such as precipitation. © 2011 Royal Meteorological Society.

Iversen T.,Norwegian Meteorological Institute | Deckmyn A.,Royal Meteorological Institute of Belgium | Santos C.,Spanish Meteorological Agency AEMET | Sattler K.,Danish Meteorological Institute | And 3 more authors.
Tellus, Series A: Dynamic Meteorology and Oceanography | Year: 2011

Grand Limited Area Model Ensemble Prediction System (GLAMEPS) is prepared for pan-European, short-range probabilistic numerical weather prediction of fine synoptic-scale, quasi-hydrostatic atmospheric flows. Four equally sized ensembles are combined: EuroTEPS, a version of the global ECMWF EPS with European target; AladEPS, a downscaling of EuroTEPS using the ALADIN model; HirEPS-K and HirEPS-S, two ensembles using the HIRLAM model nested into EuroTEPS including 3DVar data-assimilation for two control forecasts. A 52-member GLAMEPS thus samples forecast uncertainty by three analysed initial states combined with 12 singular vector-based perturbations, four different models and the stochastic physics tendencies in EuroTEPS. Over a 7-week test period in winter 2008, GLAMEPS produced better results than ECMWF's EPS with 51 ensemble members. Apart from spatial resolution, the improvement is due to the multimodel combination and to a smaller extent the dedicated EuroTEPS. Ensemble resolution and reliability are both improved. Combining uncalibrated ensembles is seen to produce a better combined ensemble than the best single-model ensemble of the same size, except when one of the single-model ensembles is considerably better than the others. Bayesian Model Averaging improves reliability, but needs further elaboration to account for geographical variations. These conclusions need to be confirmed by long-period evaluations. © 2011 The Authors Tellus A © 2011 John Wiley & Sons A/S.

Riesco Martin J.,Spanish Meteorological Agency AEMET | Mora Garcia M.,Spanish Meteorological Agency AEMET | De Pablo Davila F.,University of Salamanca | Soriano L.R.,University of Salamanca
Atmospheric Research | Year: 2014

In the present study severe rainfall (≥. 100. mm in 24. h) in the southern Mediterranean area of the Iberian Peninsula (Spanish provinces of Malaga, Granada, and Almeria) is analyzed. The spatial pattern of heavy rainfall was characterized using cluster analysis with data pertaining to 5. years (2006-2010). The areas most affected by heavy rainfall were the western and coastal areas of the province of Malaga, the border area between the provinces of Malaga and Granada, and the eastern part of the province of Almeria (5 clusters). The average synoptic patterns associated with each cluster were also obtained. A low in the western or southwestern Iberian Peninsula and southerly/southwesterly moist flow at low levels were the most frequent patterns. Two episodes of heavy rainfall that occurred during the autumn of 2012 were also studied, revealing the importance of deep convection. © 2013 Elsevier B.V.

Mora Garcia M.,Spanish Meteorological Agency AEMET | Riesco Martin J.,Spanish Meteorological Agency AEMET | Rivas Soriano L.,University of Salamanca | de Pablo Davila F.,University of Salamanca
Atmospheric Research | Year: 2015

The impact of land use on lightning activity has mainly been studied for urban areas; however the number of authors addressing the impact of vegetation on lightning is fairly limited. The relationship of different types of land use and soil (thirteen categories of land use and fourteen major soil types were considered) on cloud-to-ground lightning activity was studied in the Spanish region of Castilla-León from 2000 to 2010. To do this, urban, mining, and industrial areas were found to be associated with enhanced CG-lightning activity. With respect to natural land uses, forest and shrubland were the categories where CG-lightning was seen to be increased. By contrast, non-agricultural vegetated areas and pastures displayed the lowest CG-lightning activity. When the major soil types are considered, rendzinas, podzols, and phaeozems were found to be associated with a slight increase in CG-lightning activity and gleysols and solonchaks seem to decrease it. Assuming there are a plethora of factors which can indirectly affect the charging electromicrophysics and cloud dynamics, the authors provide evidence that soil type shows a significant correlation on CG-lightning flash density and weather characteristics are affected by land uses. It is suggested that the influence of vegetation and soil on surface moisture is one of the main effects contributing to explain the impact of land cover on CG-lightning. © 2015 Elsevier B.V.

Mora M.,Spanish Meteorological Agency AEMET | Riesco J.,Spanish Meteorological Agency AEMET | De Pablo Davila F.,University of Salamanca | Rivas Soriano L.,University of Salamanca
International Journal of Climatology | Year: 2015

A study of electrically severe thunderstorms (>2000 cloud-to-ground flashes per day) in the Spanish territory of Castilla-Leon (northern plateau of the Iberian Peninsula) has been performed using 11 years (2000-2010) of data. These episodes were classified according to average upper-level synoptic patterns. Seven synoptic patterns emerged: shortwave and very shortwave troughs, three types of lows, cyclonic vortex and ridge. The moisture content at low levels and static instability were also considered. In general, all the episodes were associated with instability and moderate moisture (11gkg-1 for the average mixing ratio at 925 hPa). The electrically severe thunderstorms associated with five synoptic patterns (shortwave and very shortwave troughs, and three types of lows) generated hail, strong winds, and intense precipitation. By contrast, the cyclonic vortex and ridge synoptic types were not associated with severe weather. © 2014 Royal Meteorological Society.

Marcos C.,Spanish Meteorological Agency AEMET | Sancho J.M.,Spanish Meteorological Agency AEMET | Tapiador F.J.,University of Castilla - La Mancha
Tethys | Year: 2015

Several precipitation products use radiances and reflectances obtained from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) to estimate convective precipitation. The direct use of these physical quantities in precipitation algorithms is known to generate an overestimation of the precipitation area and an underestimation of the rainfall rates. In order to extenuate these issues, the most recent Satellite Application Facility on Support to Nowcasting & Very Short Range Forecasting (NWC SAF/MSG) software package (version 2013) includes a new day-time algorithm that takes advantage of advances in cloud microphysics estimation, namely a better knowledge of Effective Radius (Reff), Cloud Optical Thickness (COT) and Water Phase. The improved algorithm, known as Convective Rainfall Rate from Cloud Physical Properties (CRPh), uses such Cloud Top Physical Properties (CPP) to estimate rainfall rates from convective clouds on a SEVIRI pixel basis (about 3 km at nadir). This paper presents the novelties of the new algorithm and provides both a comparison of the product with the previous versions in the NWC SAF/MSG software package, and a validation with independent ground radar data from the Spanish Radar Network operated by AEMET. Results obtained over 46 storms suggest that the CRPh provides more precise estimates than the previous algorithm, thus being more suitable for a number of quantitative applications. © 2015, Associacio Catalana de Meteorologia . All rights reserved..

Riesco Martin J.,Spanish Meteorological Agency AEMET | Mora Garcia M.,Spanish Meteorological Agency AEMET | de Pablo Davila F.,University of Salamanca | Rivas Soriano L.,University of Salamanca
Atmospheric Research | Year: 2013

A study of severe rainfall (≥. 100. mm in 24. h) over the Spanish provinces of Malaga, Granada y Almeria (close to the Alboran Sea, the westernmost part of the Mediterranean Sea) has been performed using 5. years (2006-2010) of data. The episodes of heavy rainfall were classified using the moisture flux at the 850. hPa pressure level and the lifted index. This gave three types, associated with situations of intense moisture flux and little static instability, moderate moisture flux and static instability, and moderate moisture flux and strong static instability. Representative cases of each type were analyzed, and it was found that both non-convective (41% of cases) and convective (59% of cases) systems caused the episodes of severe precipitation considered in this study. The convective structures included isolated and persistent convective systems, multicellular convective systems, and mesoscale convective systems. © 2013 Elsevier B.V.

Oteros J.,University of Cordoba, Spain | Garcia-Mozo H.,University of Cordoba, Spain | Vazquez L.,University of Cordoba, Spain | Mestre A.,Spanish Meteorological Agency AEMET | And 2 more authors.
Agriculture, Ecosystems and Environment | Year: 2013

A detailed analysis was made of the response of olive floral phenology to climate and topography in southern Spain. Field phenological, topographical and meteorological data collected at 12 sampling sites in the province of Córdoba over a 17-year period (1996-2012) were statistically analyzed and used to model local olive phenological behaviour.The study sought to determine: (1) the optimal frequency of phenological sampling during the reproductive period; (2) the major topographical parameters governing local olive reproductive phenology; and (3) the most influential meteorological variables. Findings for the Sign test indicated that weekly sampling yielded accurate results. Correlation and multiple linear regression analysis revealed that altitude and percentage eastward slope were the most influential topographical factors; a positive correlation was detected between delays in phenophases onset and increased altitude and eastward orientation. Correlation and partial least square regression analysis identified air temperature, rainfall, crop evapotranspiration and solar radiation as the major weather factors influencing local olive phenology. © 2013 Elsevier B.V.

Callado A.,Spanish Meteorological Agency AEMET | Santos C.,Spanish Meteorological Agency AEMET | Escriba P.,Spanish Meteorological Agency AEMET | Santos-Munoz D.,Spanish Meteorological Agency AEMET | And 2 more authors.
Advances in Geosciences | Year: 2011

Spanish Meteorological Agency (AEMET) runs a daily experimental multi-model Short-Range Ensemble Prediction System (AEMET-SREPS). The role of the system horizontal resolution (0.25 degrees) on the performance of 24-h precipitation probabilistic forecasts, and its relation with mesoscale events, are assessed comparing the performance over the Mediterranean area and over an European Atlantic area. Gridded high resolution rain observations and standard verification measures have been used at different precipitation thresholds, while studying the dependency on seasons for a one year period (May 2007 to June 2008). As a general result, performance over the Mediterranean area is higher than over the Atlantic one, albeit some relative loss of skill is found in autumn, when mesoscale convective organization is assumed to play a more important role. So it is suggested that AEMET-SREPS system precipitation predictability over the Mediterranean in autumn could be expected to improve if the horizontal and vertical resolution is increased in order to take into account the effect of meso-beta scale, especially important for convective organization. © Author(s) 2011.

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