Intensity-Duration-Frequency of Rainfall in Catalunya. Maximum Expected Precipitation and IDF Relationships at High Temporal and Spatial Resolution

Intensity - Duration - Frequency (IDF) relationships of extreme precipitation events are of high interest in hydrology. The building of infrastructure or designation of flood zone need, as groundwork, the recurrence intervals at which extreme episodes of rainfall can occur, i.e., the maximum intensities that can be expected for a given duration and return period. In this project 2,142 series of daily rainfall data were analysed and quality controlled after the design of a new specific procedure. The newly proposed quality control is able to classify available rainfall series according to their quality and, using this information, performs a relative comparison with nearby measures to attain a quality category for each daily value (in this project 14,144,395 measures were checked and 74% of them were considered reliable). Afterwards, climatic homogeneity of a selection of series was checked and 163 daily rainfall data series of high quality data in the temporal period 1942-2016 and uniformly distributed over the territory of Catalonia were used in the obtainment of Intensity-Duration-Frequency relationships. The obtainment of IDF was achieved by a temporal monofractal downscaling methodology implemented on a grid of high spatial resolution (1 km x 1 km) of maximum expected intensity in 24 hours. The spatial grid of maximum expected intensity in 24 hours at several return periods (2, 5, 10, 20, 50, 100, 200 and 500 years) was obtained from annual maximum precipitation in one day after correcting daily measures with an empirical factor thoroughly analysed in the scope of the project. The monofractal downscaling methodology was implemented after the obtainment of a single scaling exponent at the 163 selected locations; the scaling exponent was studied in relation to geographical and climatic characteristics of the study area. The final results of IDF relationships are provided as a set of maps that display the maximum expected intensity at a selection of durations (daily and subdaily, namely: 1h, 6h, 12h, 24h and 48h) and for a selection of return periods. The results are of high spatial resolution as they are obtained in a spatial grid of 1 km x 1 km. The results also have high temporal resolution as the intensity - frequency relationship can be calculated at any duration at the locations of the grid nodes using the provided empirical scaling exponent with validity as long as the duration ranges between 1 hour and 15 days.Les relacions d’Intensitat-Duració-Freqüència (IDF) d’episodis de pluja extrems són de gran interès en hidrologia on es necessita, com a base, els intervals de recurrència en què es donen les precipitacions extremes, és a dir, la intensitat màxima que es pot esperar per una durada i període de retorn determinats. En aquest projecte, es van analitzar 2.142 sèries de precipitació mitjançant un nou control de qualitat especialment dissenyat per a aquestes dades. El control de qualitat proposat és capaç de classificar les sèries de precipitació disponibles segons la qualitat de les dades i, utilitzant aquesta informació, fa una comparació relativa amb mesures properes per assignar una categoria a cada un dels valors diaris (es van analitzar 14.144.395 mesures i un 74% d’elles es consideren bones). També es va realitzar un control d’homogeneïtat climàtica d’una selecció de les sèries disponibles. Per obtenir la relació IDF es va fer una selecció de 163 sèries de precipitació diària de bona qualitat en el període 1942-2016 i uniformement distribuïdes pel territori de Catalunya. Les relacions IDF es van obtenir amb un mètode monofractal de downscaling temporal implementat en un grid d’alta resolució espacial (1 km x 1 km) de la intensitat màxima esperada en 24 hores. Aquest grid espacial per diversos períodes de retorn (2, 5, 10, 20, 50, 100, 200 i 500 anys) es va obtenir a partir de les sèries anuals de màxims de precipitació diària després de corregir les mesures amb un factor de correcció empíric detingudament analitzat dins del projecte. El downscaling temporal monofractal es va implementar havent obtingut un únic exponent d’escala per cada una de les 163 localitats seleccionades; l’exponent d’escala va ser àmpliament estudiat en relació amb les característiques geogràfiques i climàtiques de l’àrea d’estudi. Els resultats finals de les relacions IDF es proporcionen en un conjunt de mapes que mostren la precipitació màxima esperada a una selecció de durades (diàries i subdiàries: 1h, 6h, 12h, 24h i 48h) i per una selecció de períodes de retorn. Els resultats són d’alta resolució espacial perquè s’obtenen en un grid de 1 km x 1 km. Els resultats també són d’alta resolució temporal perquè la relació entre intensitat i freqüència es pot calcular per qualsevol durada en els nodes del grid utilitzant l’exponent d’escala proporcionat (que té validesa entre 1 hora i 15 dies).La relación de Intensidad-Duración-Frecuencia (IDF) de episodios extremos de lluvia es de gran interés en hidrología, donde se necesitan, como base, los intervalos de recurrencia de precipitaciones extremas, por lo tanto, la intensidad máxima esperada en una duración y período de retorno determinados. En este proyecto, se analizaron 2.142 series de precipitación por medio de un nuevo control de calidad especialmente diseñado para estos datos. El control de calidad propuesto es capaz de clasificar las series de precipitación disponibles según la calidad de los datos y, usando esta información, compara relativamente con medidas cercanas para asignar una categoría a cada valor diario (se analizaron 14.144.395 medidas y un 74% de ellas se consideraron buenas). También se realizó un control de homogeneidad climática de las series disponibles. Para obtener la relación IDF se seleccionaron 163 series de precipitación diaria de buena calidad en el período 1942-2016, uniformemente distribuidas por el territorio de Cataluña. La relación IDF se obtuvo con un método monofractal de downscaling temporal implementado en un grid de alta resolución espacial (1 km x 1 km) de intensidad máxima esperada en 24 horas. Este grid espacial para diferentes períodos de retorno (2, 5, 10, 20, 50, 100, 200 y 500 años) se construyó a partir de las series anuales de máxima precipitación diaria después de corregir las medidas con un factor de corrección empírico detenidamente analizado dentro del proyecto. El downscaling temporal monofractal se implementó tras la obtención de un único exponente de escala para cada una de las 163 localidades seleccionadas; el exponente de escala fue ampliamente estudiado en relación con las características geográficas y climáticas del área de estudio. Los resultados finales de la relación IDF se proporcionan en un conjunto de mapas que muestran la precipitación máxima esperada en una selección de duraciones (diarias y subdiarias: 1h, 6h, 12h, 24h y 48h) y para una selección de períodos de retorno. Los resultados son de alta resolución espacial porque se obtienen en un grid de 1km x 1km. Los resultados también son de alta resolución temporal porque la relación entre intensidad y frecuencia se puede calcular para cualquier duración en los nodos del grid usando el exponente de escala proporcionado (valido entre 1 hora y 15 días)

Implementació i verificació d'un model de radiació solar a Catalunya

Màster Oficial en Meteorologia, Departament d'Astronomia i Meteorologia (DAM), Facultat de Física, Universitat de Barcelona, Any: 2013, Director: Joan Bech RustulletResum (cat): En aquest treball s'ha implementat un model de radiació solar que permet obtenir un valor teòric per cel serè de la radiació incident en un punt qualsevol de la superfície de la Terra. Posteriorment, s'ha realitzat una verificació d'aquest model mitjançant la comparació dels valors teòrics obtinguts amb les mesures d'un període de 5 anys (2008-2012) de l'estació automàtica de l'Observatori Fabra (Barcelona) gestionada pel Servei Meteorològic de Catalunya. Els resultats obtinguts indiquen que les variacions habituals en les condicions atmosfèriques no modelitzades indueixen errors inferiors al 9% en el càlcul de la radiació teòrica per cel serè. Abstract (eng): In this academic paper a solar radiation model has been implemented, which allows us to obtain a theoretical value of solar radiation in clear sky conditions at any point on Earth's surface. After implementation, a verification of the model has been conducted by comparing the obtained values over a period of 5 years (2008-2012) with data from the automatic meteorological station of Observatori Fabra (Barcelona) managed by the Meteorological Service of Catalonia. Obtained results indicate that usual variations in atmospheric conditions not modeled produce errors which are inferior to 9% in the calculation of the theoretical value of solar radiation for clear sky

A single scaling parameter as a first approximation to describe the rainfall pattern of a place: application on Catalonia

As well as in other natural processes, it has been frequently observed that the phenomenon arising from the rainfall generation process presents fractal self-similarity of statistical type, and thus, rainfall series generally show scaling properties. Based on this fact, there is a methodology, simple scaling, which is used quite broadly to find or reproduce the intensity–duration–frequency curves of a place. In the present work, the relationship of the simple scaling parameter with the characteristic rainfall pattern of the area of study has been investigated. The calculation of this scaling parameter has been performed from 147 daily rainfall selected series covering the temporal period between 1883 and 2016 over the Catalonian territory (Spain) and its nearby surroundings, and a discussion about the relationship between the scaling parameter spatial distribution and rainfall pattern, as well as about trends of this scaling parameter over the past decades possibly due to climate change, has been presented.Peer ReviewedPostprint (author's final draft

Quality control process of the daily rainfall series available in Catalonia from 1855 to the present

The quality control of weather data is a necessity and a responsibility of meteorological services that store, distribute, and use these data. In the present work, a newly designed quality control procedure for daily rainfall data is presented after it has been adjusted and tested with more than 10^7 data from 1726 daily rainfall measurement sites in Catalonia. It is applicable to data from different origins (e.g., automatic weather stations or manual historical measurements). The procedure is focused on relative comparison of daily data with reference stations that are automatically selected after an initial estimation of their quality and a proximity study regarding location and correlation. The presented procedure has been verified taking advantage of an available network in the study area that has been routinely quality controlled by technicians of the Meteorological Service of Catalonia. The newly designed quality control procedure for daily precipitation yields good results, especially for extreme values: type I error under 10% is found for values up to 150 mm (error decreasing for lower values) and type II error is under 16% when reported values are twice a measure of 50 mm or more (error decreasing for more extreme values). After the application of the quality control procedure, a selection of series with the minimum desired quality is achieved.Peer ReviewedPostprint (author's final draft

Influence of regional and seasonal rainfall patterns on the ratio between fixed and unrestricted measured intervals of rainfall amounts

Historically, most precipitation data have been measured by collecting rainfall, usually at intervals of 24 h, with a fixed starting time. Nonetheless, it is known that the use of fixed time intervals to measure rainfall quantities could lead to an underestimation of the true maximum precipitation amounts for the considered duration, so a single multiplicative correction factor is commonly applied, generally without taking into account the rainfall pattern of the place, nor regional or seasonal considerations. In the present work, hourly measurements from 120 stations of Catalonia (northeast of the Iberian Peninsula) have been used to analyse how the ratio between rainfall amounts measured by fixed and unrestricted intervals, i.e. the correction factor, depends on the considered duration and on the specific starting time of the fixed interval (local 00:00, 08:00, 12:00 or 16:00), as well as the influence ofgeographical location and seasonality and actual rainfall duration. For fixed sampling intervals starting at 16:00, the mean correction factor has been found to be higher (1.137) than at the usual 08:00 starting time (1.129). Some geographical patterns of the correction factor over Catalonia arose which, moreover, depend on the season, with a mean value of 1.161 in spring and a value of 1.093 in summer. Also, the value of the correction has been found to increase with the actual duration of the maximum rainfall events used in the analysis. Some of these extreme events had actual mesoscale durations between 6 and 9 h, linked to highly convective mesoscale organisations acting mainly in summer and the beginning of autumn. Other maxima episodes, with more advective rainfall lasting more than 12 h registered in the northern area of the territory, presented the highest values of the correction factor, especially in spring.Peer ReviewedPostprint (author's final draft

A Simple Scaling Analysis of Rainfall in Andalusia (Spain) under Different Precipitation Regimes

A simple scaling analysis was performed in Andalusia (Spain) using daily records from 377 selected stations covering the temporal period between 1870 and 2018. Since Andalusia is a region of considerable climatic variety, with notably wet areas as well as extremely dry zones, this study is useful to investigate the relationship between the simple scaling parameter value and the characteristic rainfall regime of a place. Despite the great correspondence with the average annual precipitation (PRCPTOT), a clear dependence on rainfall irregularity was observed, revealed by the ratio of the maximum daily precipitation and PRCPTOT, as well the wet spells frequency index CWD. The spatial distribution of the simple scaling parameter captured the increasing influence of the Mediterranean Sea towards the East. The easternmost dry areas are clearly influenced by Mediterranean disturbances, with a high proportion of convective rainfall and an irregular rainfall pattern. Using a simple scaling parameter, the generalized equations of the intensity-duration-frequency (IDF) curves, of great hydrological interest were calculated for the eight Andalusian provincial capitals. Moreover, the temporal trends of this parameter in the four past decades were studied in the different areas with the aim of determining if changes in their rainfall patterns due to global warming could be detected

A simple scaling analysis of rainfall in Andalusia (Spain) under different precipitation regimes

A simple scaling analysis was performed in Andalusia (Spain) using daily records from 377 selected stations covering the temporal period between 1870 and 2018. Since Andalusia is a region of considerable climatic variety, with notably wet areas as well as extremely dry zones, this study is useful to investigate the relationship between the simple scaling parameter value and the characteristic rainfall regime of a place. Despite the great correspondence with the average annual precipitation (PRCPTOT), a clear dependence on rainfall irregularity was observed, revealed by the ratio of the maximum daily precipitation and PRCPTOT, as well the wet spells frequency index CWD. The spatial distribution of the simple scaling parameter captured the increasing influence of the Mediterranean Sea towards the East. The easternmost dry areas are clearly influenced by Mediterranean disturbances, with a high proportion of convective rainfall and an irregular rainfall pattern. Using a simple scaling parameter, the generalized equations of the intensity-duration-frequency (IDF) curves, of great hydrological interest were calculated for the eight Andalusian provincial capitals. Moreover, the temporal trends of this parameter in the four past decades were studied in the different areas with the aim of determining if changes in their rainfall patterns due to global warming could be detected.Peer ReviewedPostprint (published version

A quality control procedure for long-term series of daily precipitation data in a semiarid environment

The availability of quality precipitation records in the current climate situation is of great importance in the scientifctechnical feld but also for the public institutions that manage the meteorological networks. This work has implemented a comprehensive spatial quality control procedure in the semiarid region of Andalusia (Southern Spain), using precipitation time series from 1947 stations from three meteorological networks: Spanish Meteorological Agency (AEMET), Agroclimatic Information Network of Andalusia (RIA), and Phytosanitary Information Alert Network (RAIF). The method consists of three consecutive steps: basic, absolute, and relative quality control processes. The latter step compares data from neighboring stations taking into account their proximity, height diference, and correlation, leading to a complete evaluation of each daily value. Finally, the quality of each year at each station can be declared as acceptable, good, or excellent. The automatic weather station networks RIA and RAIF gave absolute quality index Q above 85% for almost 87% of their stations, while only 57% of AEMET network reached this percentage. However, one of the longest AEMET datasets, San Fernando-Cádiz, obtained, except for 1 year, Q values over 90% in all available years for more than a century of measurements, since 1870 until 2000. From a total of more than 15 million daily records, almost 82% was fagged as correct. Despite the limitations of Andalusia region (low density of stations and its structural water defcit), the complete quality control procedure has been satisfactorily applied. Finally, related to the number of outliers, no temporal trend was found across the region.Peer ReviewedPostprint (published version

Quality Management Framework for Climate Datasets

Data from a variety of research programmes are increasingly used by policy makers, researchers, and private sectors to make data-driven decisions related to climate change and variability. Climate services are emerging as the link to narrow the gap between climate science and downstream users. The Global Framework for Climate Services (GFCS) of the World Meteorological Organization (WMO) offers an umbrella for the development of climate services and has identified the quality assessment, along with its use in user guidance, as a key aspect of the service provision. This offers an extra stimulus for discussing what type of quality information to focus on and how to present it to downstream users. Quality has become an important keyword for those working on data in both the private and public sectors and significant resources are now devoted to quality management of processes and products. Quality management guarantees reliability and usability of the product served, it is a key element to build trust between consumers and suppliers. Untrustworthy data could lead to a negative economic impact at best and a safety hazard at worst. In a progressive commitment to establish this relation of trust, as well as providing sufficient guidance for users, the Copernicus Climate Change Service (C3S) has made significant investments in the development of an Evaluation and Quality Control (EQC) function. This function offers a homogeneous user-driven service for the quality of the C3S Climate Data Store (CDS). Here we focus on the EQC component targeting the assessment of the CDS datasets, which include satellite and in-situ observations, reanalysis, climate projections, and seasonal forecasts. The EQC function is characterised by a two-tier review system designed to guarantee the quality of the dataset information. While the need of assessing the quality of climate data is well recognised, the methodologies, the metrics, the evaluation framework, and how to present all this information to the users have never been developed before in an operational service, encompassing all the main climate dataset categories. Building the underlying technical solutions poses unprecedented challenges and makes the C3S EQC approach unique. This paper describes the development and the implementation of the operational EQC function providing an overarching quality management service for the whole CDS data.This study is based on work carried out in the C3S_512 contract funded by Copernicus Programme and operated by ECMWF on behalf of the European Commission (Service Contract number: ECMWF/COPERNICUS720187C3S_512_BSC). We would like to acknowledge the work of colleagues from several European institutions, the data providers and C3S, who contributed to the development of the EQC framework as well as to the QAR production. We would also like to acknowledge the focus group users, who took time to review and provide valuable feedback on the QARs, QATs, minimum requirements and the CDS quality assessment tab. The authors are grateful to the anonymous reviewers for their constructive comments that have helped for the improvement of this paper.Peer Reviewed"Article signat per 23 autors/es: Carlo Lacagnina , Francisco Doblas-Reyes, Gilles Larnicol, Carlo Buontempo, André Obregón, Montserrat Costa-Surós, Daniel San-Martín, Pierre-Antoine Bretonnière, Suraj D. Polade, Vanya Romanova, Davide Putero, Federico Serva, Alba Llabrés-Brustenga, Antonio Pérez, Davide Cavaliere, Olivier Membrive, Christian Steger, Núria Pérez-Zanón, Paolo Cristofanelli, Fabio Madonna, Marco Rosoldi, Aku Riihelä, Markel García Díez"Postprint (published version

Intensity-Duration-Frequency of Rainfall in Catalunya. Maximum Expected Precipitation and IDF Relationships at High Temporal and Spatial Resolution

[eng] Intensity - Duration - Frequency (IDF) relationships of extreme precipitation events are of high interest in hydrology. The building of infrastructure or designation of flood zone need, as groundwork, the recurrence intervals at which extreme episodes of rainfall can occur, i.e., the maximum intensities that can be expected for a given duration and return period. In this project 2,142 series of daily rainfall data were analysed and quality controlled after the design of a new specific procedure. The newly proposed quality control is able to classify available rainfall series according to their quality and, using this information, performs a relative comparison with nearby measures to attain a quality category for each daily value (in this project 14,144,395 measures were checked and 74% of them were considered reliable). Afterwards, climatic homogeneity of a selection of series was checked and 163 daily rainfall data series of high quality data in the temporal period 1942-2016 and uniformly distributed over the territory of Catalonia were used in the obtainment of Intensity-Duration-Frequency relationships. The obtainment of IDF was achieved by a temporal monofractal downscaling methodology implemented on a grid of high spatial resolution (1 km x 1 km) of maximum expected intensity in 24 hours. The spatial grid of maximum expected intensity in 24 hours at several return periods (2, 5, 10, 20, 50, 100, 200 and 500 years) was obtained from annual maximum precipitation in one day after correcting daily measures with an empirical factor thoroughly analysed in the scope of the project. The monofractal downscaling methodology was implemented after the obtainment of a single scaling exponent at the 163 selected locations; the scaling exponent was studied in relation to geographical and climatic characteristics of the study area. The final results of IDF relationships are provided as a set of maps that display the maximum expected intensity at a selection of durations (daily and subdaily, namely: 1h, 6h, 12h, 24h and 48h) and for a selection of return periods. The results are of high spatial resolution as they are obtained in a spatial grid of 1 km x 1 km. The results also have high temporal resolution as the intensity - frequency relationship can be calculated at any duration at the locations of the grid nodes using the provided empirical scaling exponent with validity as long as the duration ranges between 1 hour and 15 days.[cat] Les relacions d’Intensitat-Duració-Freqüència (IDF) d’episodis de pluja extrems són de gran interès en hidrologia on es necessita, com a base, els intervals de recurrència en què es donen les precipitacions extremes, és a dir, la intensitat màxima que es pot esperar per una durada i període de retorn determinats. En aquest projecte, es van analitzar 2.142 sèries de precipitació mitjançant un nou control de qualitat especialment dissenyat per a aquestes dades. El control de qualitat proposat és capaç de classificar les sèries de precipitació disponibles segons la qualitat de les dades i, utilitzant aquesta informació, fa una comparació relativa amb mesures properes per assignar una categoria a cada un dels valors diaris (es van analitzar 14.144.395 mesures i un 74% d’elles es consideren bones). També es va realitzar un control d’homogeneïtat climàtica d’una selecció de les sèries disponibles. Per obtenir la relació IDF es va fer una selecció de 163 sèries de precipitació diària de bona qualitat en el període 1942-2016 i uniformement distribuïdes pel territori de Catalunya. Les relacions IDF es van obtenir amb un mètode monofractal de downscaling temporal implementat en un grid d’alta resolució espacial (1 km x 1 km) de la intensitat màxima esperada en 24 hores. Aquest grid espacial per diversos períodes de retorn (2, 5, 10, 20, 50, 100, 200 i 500 anys) es va obtenir a partir de les sèries anuals de màxims de precipitació diària després de corregir les mesures amb un factor de correcció empíric detingudament analitzat dins del projecte. El downscaling temporal monofractal es va implementar havent obtingut un únic exponent d’escala per cada una de les 163 localitats seleccionades; l’exponent d’escala va ser àmpliament estudiat en relació amb les característiques geogràfiques i climàtiques de l’àrea d’estudi. Els resultats finals de les relacions IDF es proporcionen en un conjunt de mapes que mostren la precipitació màxima esperada a una selecció de durades (diàries i subdiàries: 1h, 6h, 12h, 24h i 48h) i per una selecció de períodes de retorn. Els resultats són d’alta resolució espacial perquè s’obtenen en un grid de 1 km x 1 km. Els resultats també són d’alta resolució temporal perquè la relació entre intensitat i freqüència es pot calcular per qualsevol durada en els nodes del grid utilitzant l’exponent d’escala proporcionat (que té validesa entre 1 hora i 15 dies).[spa] La relación de Intensidad-Duración-Frecuencia (IDF) de episodios extremos de lluvia es de gran interés en hidrología, donde se necesitan, como base, los intervalos de recurrencia de precipitaciones extremas, por lo tanto, la intensidad máxima esperada en una duración y período de retorno determinados. En este proyecto, se analizaron 2.142 series de precipitación por medio de un nuevo control de calidad especialmente diseñado para estos datos. El control de calidad propuesto es capaz de clasificar las series de precipitación disponibles según la calidad de los datos y, usando esta información, compara relativamente con medidas cercanas para asignar una categoría a cada valor diario (se analizaron 14.144.395 medidas y un 74% de ellas se consideraron buenas). También se realizó un control de homogeneidad climática de las series disponibles. Para obtener la relación IDF se seleccionaron 163 series de precipitación diaria de buena calidad en el período 1942-2016, uniformemente distribuidas por el territorio de Cataluña. La relación IDF se obtuvo con un método monofractal de downscaling temporal implementado en un grid de alta resolución espacial (1 km x 1 km) de intensidad máxima esperada en 24 horas. Este grid espacial para diferentes períodos de retorno (2, 5, 10, 20, 50, 100, 200 y 500 años) se construyó a partir de las series anuales de máxima precipitación diaria después de corregir las medidas con un factor de corrección empírico detenidamente analizado dentro del proyecto. El downscaling temporal monofractal se implementó tras la obtención de un único exponente de escala para cada una de las 163 localidades seleccionadas; el exponente de escala fue ampliamente estudiado en relación con las características geográficas y climáticas del área de estudio. Los resultados finales de la relación IDF se proporcionan en un conjunto de mapas que muestran la precipitación máxima esperada en una selección de duraciones (diarias y subdiarias: 1h, 6h, 12h, 24h y 48h) y para una selección de períodos de retorno. Los resultados son de alta resolución espacial porque se obtienen en un grid de 1km x 1km. Los resultados también son de alta resolución temporal porque la relación entre intensidad y frecuencia se puede calcular para cualquier duración en los nodos del grid usando el exponente de escala proporcionado (valido entre 1 hora y 15 días)