Clustering-based analysis of climate time series. Development and applications.

RESUMEN: La cantidad de datos climáticos aumenta continuamente en volumen y complejidad a la vez que lo hace el número de usuarios dentro de la comunidad científica y su público. En este contexto, las técnicas de procesamiento de señales permiten resumir el contenido y facilitan su utilización en múltiples aplicaciones. El objetivo de este trabajo está orientado al tratamiento de señales (en concreto series temporales de situaciones atmosféricas a escala sinóptica) y su clasificación y agrupamiento en conjuntos más sencillos que facilitan su análisis e interpretación. Para ello se implementarán una serie de métodos estadísticos de tratamiento de datos relacionados con las técnicas de segmentación o clustering, las cuales se aplicarán a señales correspondientes a Modelos Climáticos Globales (GCMs) con el fin de crear patrones de tiempo (clusters), agrupando las señales más similares entre sí. La comparación de los clusters extraídos de los modelos con los de productos de reanálisis (pseudo-observaciones) permite evaluar la capacidad de los GCMs para representar de manera fidedigna la circulación atmosférica de larga escala. Esta validación resulta de gran interés para las aplicaciones del ámbito de las técnicas de regionalización del clima y de estudios de cambio climático, donde la elección de un GCM u otro tiene un gran impacto en los resultados finales.ABSTRACT: The amount of climate data is constantly expanding in volume and complexity as the number of users within the scientific community and its public increase. In this context, signal processing allows summarizing the data and facilitate its use in multiple applications. The aim of this work is oriented to the signal processing (in particular, climate time series of atmospheric situations at a synoptic scale) and their classification into simpler sets that facilitate their analysis and interpretation. A series of statistical data processing methods related to clustering techniques will be implemented for this purpose. Clustering analysis will be applied to signals from Global Climate Models (GCMs) in order to create climate types, grouping the most similar signals among them. The comparison between the clusters extracted from the models with those from reanalysis products (pseudo-observations) allows to perform an evaluation of the capacity of GCMs to accurately represent large-scale atmospheric circulation patterns. This validation exercise is of paramount importance in climate science applications, such as the application of downscaling techniques in climate change studies, where the choice of the driving GCM has a great impact on the final results.Máster en Ingeniería de Telecomunicació

A global climate model performance atlas for the southern hemisphere extratropics based on regional atmospheric circulation patterns

The performance of 61 global climate models participating in CMIP5 and 6 is evaluated for the Southern Hemisphere extratropics in terms of typical regional-scale atmospheric circulation patterns. These patterns are known to be linked with a number of key variables in atmospheric physics and chemistry and provide an overarching concept for model evaluation. First, hemispheric-wide error and ranking maps are provided for each model and regional details are described. Then, the results are compared with those obtained in a companion study for the Northern Hemisphere. For most models, the average error magnitude and ranking position is similar on both hemispheres, ruling out systematic tuning toward either of the two. CMIP6 models perform better on average than CMIP5 models and the interactive simulation of more climate system components does not deteriorate the results for most model families. Better performance is associated with higher resolution in the atmosphere, following a non-linear relationship.This research work was funded by the European Commission – Next-GenerationEU (Regulation EU 2020/2094), through CSIC's Interdis-ciplinary Thematic Platform Clima (PTI Clima)/Development of Oper-ational Climate Services and by the I+D+i project CORDyS (PID2020-116595RB-I00), funded by MCIN/AEI/10.13039/501100011033. J.A.F. acknowledges support from project ATLAS (PID2019-111481RB-I00), grant PRE2020-094728 funded by MCIN/AEI/10.13039/501100011033 and ESF investing in your future. A.C. acknowl-edges support from Project COMPOUND (TED2021-131334A-I00) funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGener-ationEU/PRTR. S.B. would like to thank CESGA and AMTEGA for providing computational resources. The authors acknowledge the public availability of the CMIP datasets via the ESGF data portals, as well the free distribution of the ECMWF and JMA reanalysis products

Exploring the limits of the Jenkinson–Collison weather types classification scheme: a global assessment based on various reanalyses

The Jenkinson-Collison weather typing scheme (JC-WT) is an automated method used to classify regional sea-level pressure into a reduced number of typical recurrent patterns. Originally developed for the British Isles in the early 1970´s on the basis of expert knowledge, the method since then has seen many applications. Encouraged by the premise that the JC-WT approach can in principle be applied to any mid-to-high latitude region, the present study explores its global extra-tropical applicability, including the Southern Hemisphere. To this aim, JC-WT is applied at each grid-box of a global 2.5º regular grid excluding the inner tropics (± 5º band). Thereby, 6-hourly JC-WT catalogues are obtained for 5 distinct reanalyses, covering the period 1979-2005, which are then applied to explore (1) the limits of method applicability and (2) observational uncertainties inherent to the reanalysis datasets. Using evaluation criteria, such as the diversity of occurring circulation types and the frequency of unclassified situations, we extract empirically derived applicability thresholds which suggest that JC-WT can be generally used anywhere polewards of 23.5º, with some exceptions. Seasonal fluctuations compromise this finding along the equatorward limits of the domain. Furthermore, unreliable reanalysis sea-level pressure estimates in elevated areas with complex orography (such as the Tibetan Plateau, the Andes, Greenland and Antarctica) prevent the application of the method in these regions. In some other regions, the JC-WT classifications obtained from the distinct reanalyses substantially differ from each other, which may bring additional uncertainties when the method is used in model evaluation experiments.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This paper is part of the R+D+i projects CORDyS (PID2020-116595RB-I00) and ATLAS (PID2019-111481RBI00), funded by MCIN/AEI/10.13039/501100011033. J.A.F. has received research support from grant PRE2020-094728 funded by MCIN/AEI/10.13039/501100011033. J.B. and A.C. received research support from the project INDECIS, part of the European Research Area for Climate Services Consortium (ERA4CS) with co-funding by the European Union (grant no. 690462)

Weather-type-conditioned calibration of Tropical Rainfall Measuring Mission precipitation over the South Pacific Convergence Zone

The South Pacific region is an area affected by characteristic precipitation patterns undergoing extreme events such as tropical cyclones and droughts. First, a daily weather typing of precipitation is presented, based on principal component analysis and k-means clustering using precipitation and atmospheric circulation variables derived from sea-level pressure and wind reanalysis fields. As a result, five weather types (WTs) are presented, able to capture distinct precipitation spatiotemporal patterns, interpretable in terms of salient regional climate features. Second, we undertake the calibration of the TRMM precipitation product using a set of rain gauge stations as reference and scaling and empirical quantile mapping (eQM) as calibration techniques. Furthermore, we build upon the weather-type classification to compare the results with a WTconditioned calibration approach. Overall, our results underpin the need of adjusting the existing TRMM biases, mostly relevant for the upper tail of their distribution, and advocate the use of correction techniques able to deal with quantile-dependent biases-such as eQM-instead of a simple scaling, in order to obtain a more realistic representation of extreme precipitation events. The conditioning has shown only a marginal added value over the simple approach, although this minor improvement may prove relevant for applications focused on extreme event analysis. Furthermore, the weather types created can be applied to a wide variety of conditioned analyses in this region.AFRICULTURES, Grant/Award Number: 774652; Beach4Cast, Grant/Award Number: PID2019-107053RB-I00; CORDyS, Grant/Award Number: PID2020-116595RB-I00; INDECIS, Grant/Award Number: 69046

Accurate and timely diagnosis of Eosinophilic Esophagitis improves over time in Europe. An analysis of the EoE CONNECT Registry

BACKGROUND: Poor adherence to clinical practice guidelines for eosinophilic esophagitis (EoE) has been described and the diagnostic delay of the disease continues to be unacceptable in many settings. OBJECTIVE: To analyze the impact of improved knowledge provided by the successive international clinical practice guidelines on reducing diagnostic delay and improving the diagnostic process for European patients with EoE. METHODS: Cross‐sectional analysis of the EoE CONNECT registry based on clinical practice. Time periods defined by the publication dates of four major sets of guidelines over 10 years were considered. Patients were grouped per time period according to date of symptom onset. RESULTS: Data from 1,132 patients was analyzed and median (IQR) diagnostic delay in the whole series was 2.1 (0.7‐6.2) years. This gradually decreased over time with subsequent release of new guidelines (p < 0.001), from 12.7 years up to 2007 to 0.7 years after 2017. The proportion of patients with stricturing of mixed phenotypes at the point of EoE diagnosis also decreased over time (41.3% vs. 16%; p < 0.001), as did EREFS scores. The fibrotic sub‐score decreased from a median (IQR) of 2 (1‐2) to 0 (0‐1) when patients whose symptoms started up to 2007 and after 2017 were compared (p < 0.001). In parallel, symptoms measured with the Dysphagia Symptoms Score reduced significantly when patients with symptoms starting before 2007 and after 2012 were compared. A reduction in the number of endoscopies patients underwent before the one that achieved an EoE diagnosis, and the use of allergy testing as part of the diagnostic workout of EoE, also reduced significantly over time (p = 0.010 and p < 0.001, respectively). CONCLUSION: The diagnostic work‐up of EoE patients improved substantially over time at the European sites contributing to EoE CONNECT, with a dramatic reduction in diagnostic delay

EoE CONNECT, the European Registry of Clinical, Environmental, and Genetic Determinants in Eosinophilic Esophagitis: rationale, design, and study protocol of a large-scale epidemiological study in Europe

Background: The growing prevalence of eosinophilic esophagitis (EoE) represents a considerable burden to patients and health care systems. Optimizing cost-effective management and identifying mechanisms for disease onset and progression are required. However, the paucity of large patient cohorts and heterogeneity of practice hinder the defining of optimal management of EoE. Methods: EoE CONNECT is an ongoing, prospective registry study initiated in 2016 and currently managed by EUREOS, the European Consortium for Eosinophilic Diseases of the Gastrointestinal Tract. Patients are managed and treated by their responsible specialists independently. Data recorded using a web-based system include demographic and clinical variables; patient allergies; environmental, intrapartum, and early life exposures; and family background. Symptoms are structurally assessed at every visit; endoscopic features and histological findings are recorded for each examination. Prospective treatment data are registered sequentially, with new sequences created each time a different treatment (active principle, formulation, or dose) is administered to a patient. EoE CONNECT database is actively monitored to ensure the highest data accuracy and the highest scientific and ethical standards. Results: EoE CONNECT is currently being conducted at 39 centers in Europe and enrolls patients of all ages with EoE. In its aim to increase knowledge, to date EoE CONNECT has provided evidence on the effectiveness of first- and second-line therapies for EoE in clinical practice, the ability of proton pump inhibitors to induce disease remission, and factors associated with improved response. Drug effects to reverse fibrous remodeling and endoscopic features of fibrosis in EoE have also been assessed. Conclusion: This prospective registry study will provide important information on the epidemiological and clinical aspects of EoE and evidence as to the real-world and long-term effectiveness and safety of therapy. These data will potentially be a vital benchmark for planning future EoE health care services in Europe

Study and implementation of depth map from Stereo Matching algorithm

RESUMEN: En este trabajo, se presenta un estudio del algoritmo Stereo Matching y un análisis teórico de las técnicas más utilizadas para su implementación. Además, se desarrolla dicho algoritmo en C++ para obtener mapas de profundidad a partir de una escena con imágenes estéreo en tiempo real. Estos mapas de profundidad representan modelos 3D sencillos de interpretar y sirven como punto de partida para reconstrucciones 3D más complejas. Finalmente, se analizan los resultados obtenidos y se plantean opciones de mejora en cuanto al rendimiento del algoritmo y a la calidad de los mapas de profundidad, con el fin de ayudar a alcanzar mejores implementaciones futuras del mismo en tiempo real utilizando sistemas embebidos.ABSTRACT: This document presents a study of the Stereo Matching algorithm, with a theoretical analysis of all the techniques used on its development. After that, a C++ implementation is suggested in order to obtain real-time Depth maps from Stereo Cameras. Finally, the results of the implementation are evaluated, so improvements regarding reconstruction quality and performance can be proposed with the purpose of improving future implementations in embedded systems.Grado en Ingeniería de Tecnologías de Telecomunicació

Accurate and timely diagnosis of Eosinophilic Esophagitis improves over time in Europe. An analysis of the EoE CONNECT Registry

Poor adherence to clinical practice guidelines for eosinophilic esophagitis (EoE) has been described and the diagnostic delay of the disease continues to be unacceptable in many settings. To analyze the impact of improved knowledge provided by the successive international clinical practice guidelines on reducing diagnostic delay and improving the diagnostic process for European patients with EoE. Cross-sectional analysis of the EoE CONNECT registry based on clinical practice. Time periods defined by the publication dates of four major sets of guidelines over 10 years were considered. Patients were grouped per time period according to date of symptom onset. Data from 1,132 patients was analyzed and median (IQR) diagnostic delay in the whole series was 2.1 (0.7-6.2) years. This gradually decreased over time with subsequent release of new guidelines (p < 0.001), from 12.7 years up to 2007 to 0.7 years after 2017. The proportion of patients with stricturing of mixed phenotypes at the point of EoE diagnosis also decreased over time (41.3% vs. 16%; p < 0.001), as did EREFS scores. The fibrotic sub-score decreased from a median (IQR) of 2 (1-2) to 0 (0-1) when patients whose symptoms started up to 2007 and after 2017 were compared (p < 0.001). In parallel, symptoms measured with the Dysphagia Symptoms Score reduced significantly when patients with symptoms starting before 2007 and after 2012 were compared. A reduction in the number of endoscopies patients underwent before the one that achieved an EoE diagnosis, and the use of allergy testing as part of the diagnostic workout of EoE, also reduced significantly over time (p = 0.010 and p < 0.001, respectively). The diagnostic work-up of EoE patients improved substantially over time at the European sites contributing to EoE CONNECT, with a dramatic reduction in diagnostic delay