Estudio experimental de la respuesta de la temperatura mínima del aire a condiciones de exposición con y sin protección de garita meteorológica

Ponencia presentada en: VI Congreso Internacional de la Asociación Española de Climatología celebrado en Tarragona del 8 al 11 de octubre de 2008.[ES]El objetivo de este trabajo experimental es cuantificar la respuesta de la temperatura mínima del aire a condiciones de exposición termométrica con y sin protección de garita meteorológica. Para llevar a cabo este estudio se han registrado medidas simultáneas de la temperatura nocturna del aire dentro y fuera de garita en la estación meteorológica oficial de Villena-Ciudad (sureste de la Península Ibérica, PI; Alicante) durante un periodo anual (2007-2008). Los resultados preliminares muestran que la temperatura mínima del aire se subestima fuera del abrigo meteorológico debido a la radiación terrestre de onda larga; que la subestimación es más notable durante los meses de invierno en relación a una mayor irradiación nocturna respecto al periodo estival; y que la influencia de la humedad del aire sobre las diferencias térmicas es relativamente débil.[EN]The aim of this experimental work is to quantify the response of minimum air temperature to temperature exposure conditions with and without screen protection. For carrying out this study simultaneous measurements of night-time air temperature inside and outside the screen has been recorded in the official weather station of Villena-City (southeast region of the Iberian Peninsula, IP; Alicante) during 1-yr study period (2007-2008). The preliminary results show that minimum air temperature is underestimated outside the screen due to outgoing longwave radiation; this underestimation is more significant during winter months in relation to the greater night-irradiation than summer period; and the influence of air humidity on the thermal differences is relatively weak.Este trabajo se ha llevado a cabo en el seno del Grup de Climatologia de la Universitat de Barcelona (2005SGR 01034) y del proyecto IPIBEX (CGL2005-07664-C02-01)

Estimación de la ocurrencia de la brisa marina en Alicante

Ponencia presentada en: IV Congreso de la Asociación Española de Climatología "El Clima entre el Mar y la Montaña", celebrado en Santander del 2 al 5 de noviembre de 2004.[ES]En este trabajo se define el grado de ocurrencia de las circulaciones de vientos en régimen de brisa marina en el espacio litoral de la comarca del Campo de Alicante, durante el quinquenio 1999-2003. Para estimarlo se plantea una metodología para la selección de los días con disparo de la brisa marina y de su aplicación manual se obtienen unos resultados preliminares, a partir de los cuales se valora la ocurrencia del fenómeno. El presente estudio demuestra la capacidad de soplo de la marinada durante todo el año, en función de la sucesión de favorables marcos atmosféricos sobre la escena sinóptica del Levante español. Los primeros resultados obtenidos ponen de manifiesto que la brisa marina no es, como se ha estudiado, un mecanismo “exclusivo” del verano astronómico mediterráneo, sino que se comprueba que, en términos de ocurrencia, en invierno este fenómeno también puede llegar a ser importante en la dinámica atmosférica de todo el espacio litoral alicantino.[EN]This paper is aimed at defining the degree of occurrence of wind circulations in sea breeze regime along the coastline of the regional area called Campo de Alicante, during the five-year period between 1999 and 2003. In order to measure this degree of occurrence, a methodology for the selection of those days in which sea breeze is triggered has been set up. The results obtained after its manual application are used to estimate the occurrence of the phenomenon. This study shows the gust capacity of the marinada during the whole year, depending on the successive favourable atmospheric scenarios over the synoptic pattern of the Levant region of Spain. The first results obtained show that sea breeze is not, as it has been studied, an “exclusive” mechanism of the Mediterranean astronomical summer. However, it can be observed that, as far as its degree of occurrence is concerned, this phenomenon may become important for atmospheric dynamics during the winter on the coast of Alicante

Homogenization of daily peak wind gust series from Spain and Portugal

Presentación realizada en: 10th EUMETNET Data Management Workshop celebrado en St. Gallen, Suiza, del 28 al 30 de octubre de 2015.Daily peak wind gusts series from 80 stations (7 from Portugal and 73 from Spain) spanning 54 years (1961-2014) were subjected to a robust quality control, reconstructionand relative homogenization protocol using the R package 'Climatol', with and without using MM5 model simulation outputs as homogeneous reference series. As daily series are much noisier than their monthly aggregates, homogenization at the monthly scale was also performed, resulting in the detection and correction of 171 shifts in the series (almost double than the 87 shifts corrected directly on the daily series). Discussions of the results include comparisons of different statistical parameters derived from: · The raw series · Series homogenized directly at the daily scale · Series homogenized at the monthly scale · Daily series adjusted with the monthly homogenization correction factors And the statistical parameters compared include: · Trends · Return periods · Number of days with peak wind gust greater than the 90 percentile Lessons learned will help in improving the methodology to analyze climatological series of extreme weather events, and particularly our understanding of the daily peak wind gust variability and trends

Impact of two different sized Stevenson screens on air temperature measurements

In this study we evaluated the impact of the size of two naturally ventilated wooden Stevenson screens on air temperature measurements in the first‐order meteorological station of Calamocha (northeastern Iberian Peninsula, Spain). The 1‐year field experiment consisted of comparing air temperatures measured at the two most commonly sized Stevenson screens used by the Spanish Meteorological State Agency (AEMET) since last century; the medium‐sized Stevenson screen employed at the second‐order weather stations, versus the large‐sized Stevenson screen mainly used at the first‐order meteorological stations. The main objective was to report the air temperature difference between these two differently sized Stevenson screens, and to study the impact on the observed differences of some weather elements (i.e. relative humidity, wind speed, total cloud cover, atmospheric pressure and global solar radiation). The results show that the medium‐sized Stevenson screen tended to overheat daily maximum air temperatures (0.54 °C on yearly average) and also air temperatures recorded at 1300 UTC. The differences on daily minimum air temperatures were negligible (−0.11 °C on yearly average). This overheating bias (not statistically significant) occurred under anticyclonic situations that lead to clear skies, high solar radiation, weak winds and low relative humidity. The bias appeared throughout the whole year but in particular during the warm season from May through October. Air temperature observations from the nearby station Daroca confirmed an overheating bias introduced by a change from a large‐sized Stevenson screen to a medium‐sized one in Calamocha.This research was supported by (1) the JCI-2011-10263 grant, (2) the projects CGL2011-27574-C02-02 and CGL2011-27536/HID financed by the Spanish Commission of Science and Technology and FEDER and (3) the MEDACC project (LIFE12 ENV/ES/000536)

Homogenization of near-surface wind speed and gust series across Sweden

Póster presentado en: EGU General Assembly 2019 celebrada del 7 al 12 de abril en Viena, Austria.Studies which evaluate the impact of wind-related hazards need to have access to reliable and homogeneous measurements. Unfortunately, observed wind series can be affected by several non-climatic artifacts, which may introduce inhomogeneities that mislead the study of climate trends and multi-decadal variability. This study compares different homogenization approaches using the R-package CLIMATOL to identify the best technique for homogenizing near-surface mean wind speed (WS) and daily peak wind gust (DPWG, i.e. the highest near-surface wind gust speed recorded in 24 hours) across Sweden.This work has been supported by the project “Detection and attribution of changes in extreme wind gusts over land” (2017-03780) funded by the Swedish Research Council

Observed and simulated trends of daily peak wind gusts across northern Europe

Póster presentado en: EMS Annual Meeting: European Conference for Applied Meteorology and Climatology celebrado del 4 al 8 de septiembre de 2017 en Dublin, IrlandaExtreme wind hazards have a substantial societal and environmental impact. Due to their complex origins, there are great knowledge gaps about their variations and the associated mechanisms, which makes the prediction challenging. Specifically there is a urgent need to evaluate numerical models’ capability in simulate extreme wind conditions. This study focuses on assessing variabilities and trends of Daily Peak Wind Gust (DPWG) and its extreme (defined as 90th percentile) cross Northern Europe, based on observation during 1996-2016 and Regional Climate Model (RCM) simulations for 1970-2016. The aim is to evaluate RCMs’ ability in simulating past changes of the DPWG and its extreme as reflected in the observations. RCMs are the key tools available for the prediction of wind conditions. An improved understanding about how these models perform can help identify eventual deficiencies in the models, which may enhance our prediction ability

Sea breeze convergence and convective cloud frequencies from AVHRR data over the Isle of Mallorca

Póster presentado en: 7th Annual Meeting of the European Meteorological Society/8th European Conference on Applications of Meteorology celebrado en San Lorenzo del Escorial, del 1 al 5 de octubre de 2007.The short-term forecast of the timing, location and intensity of sea breeze convection is currently one of the most difficult atmospheric phenomena, as forecasting tools available are not enough. The line of Cu clouds associated with low level sea breeze convergence and sea breeze complex interactions with features of coastline, small-scale terrain and large-scale synoptic flows is the main feature of this β-mesoscale circulation over the Isle of Mallorca. The boundary layer convergence zones developed by sea breezes can trigger scattered local heavy showers and thunderstorms under conditionally unstable atmosphere, which sometimes can be extraordinarily severe, producing hailstone and gusty winds. AVHRR data from the NOAA-17 (0900-1200 UTC) and NOAA16 (1200-1500 UTC) satellites were collected during 8-month study period (March-October 2004) for computing high-resolution (1.1 km) convective cloud masks making use of a new APOLLO cloud detection algorithm. A non-eulerian numerical model is used in order to simulate the diurnal evolution of mesoscale sea breeze field and calculate wind convergence values for a high resolution grid-point basis covering the centre of the Isle of Mallorca and surrounding Mediterranean sea. This study attempts to statistically verify the impact of low-level convergence of sea breezes on convective cloud development. The two-dimensional numerical model is capable of forecasting a reasonably accurate location of most prominent convective zones mapped by the cloud detection algorithm. Three case studies on influences of different intensities of low-level sea breeze convergence upon convective development were simulated: (1) September 17th, 2004 represents an episode of weak sea breeze convergence; (2) June 17th, 2004 corresponds to a light to moderate sea breeze convergence; and (3) July 27th, 2004 illustrates a strong sea breeze convergence.The study was supported by Spain’s Education and Science Ministry (MEC) project IPIBEX (CGL2005-07664-C02-01)

WeMOi: criterio objetivo de selección de la brisa marina en el sureste de la Península Ibérica (Alicante)

Ponencia presentada en: V Congreso Internacional de la Asociación Española de Climatología celebrado en Zaragoza del 18 al 21 de septiembre de 2006.[ES]El objetivo de este estudio es presentar el índice diario de la Oscilación del Mediterráneo Occidental (WeMOi) como un nuevo filtro automático de selección de la brisa marina. La variabilidad sinóptica a escala diaria es el primer factor que determina el desarrollo de la brisa marina. Escenarios sinópticos con débil gradiente de presión en superficie, fracción de insolación elevada y forzamiento térmico diurno entre tierra y mar, representan factores determinantes para el disparo de esta circulación local de viento. En este trabajo se utiliza este patrón de teleconexión regional para cuantificar la influencia del factor sinóptico y seleccionar de forma objetiva la brisa marina. Se han correlacionado los valores diarios del índice con la base de datos cualitativa y cuantitativa de días de brisa marina construida para Alicante (1999-2000). El intervalo diario del WeMOi [-1, 1] se utiliza como primer criterio objetivo para detectar condiciones sinópticas estables en superficie que potencian el disparo de la brisa marina en el sureste de la Península Ibérica (Alicante).[EN]The aim of this study is to present the daily Western Mediterranean Oscillation index (WeMOi) as a new automatic filter for selecting the sea breeze. The synoptic variability on a daily resolution is the primary factor that determines the development of the sea breeze. Synoptic patterns with a weak surface pressure gradient, high insolation fraction and diurnal thermal forcing between land and sea are determinant factors for the onset of this mesoescalar wind circulation. This work uses this regional teleconnection pattern in order to quantify the synoptic factor influence and to select objectively the sea breeze. It has been correlated the daily values of the index with the qualitative and quantitative database of sea breeze days created for Alicante (1999-2000). The [-1, 1] interval of the daily WeMOi has been selected as the objective primary criterion to detect stable synoptic conditions on surface that favours the sea breeze triggering on the southeastern of the Iberian Peninsula (Alicante).Este estudio se ha realizado en el marco de las estructuras de investigación del Grup de Climatologia de la Universitat de Barcelona (2005SGR-01034) y del Proyecto IPIBEX (CGL2005-07664-C02-01/CLI)