Northern Chile is one of the most arid regions in the world, with precipitation mainly occurring during austral summer, between December and April. The aim of this study is to classify the main weather regimes derived from sea level pressure, surface wind speed, 500 or 250 hPa geopotential heights, in order to measure their influence on precipitation anomalies and determine if they can be considered sources of predictability of rainfall in this region. Four weather regimes were found to optimally describe atmospheric circulation in the study area during 1966-2015 and for each of the four levels described above. Using daily precipitation data from a network of 161 meteorological stations across the region, the rainfall anomalies associated with each weather regime were quantified. They are coherent with the direction of flow derived from pressure and geopotential anomalies, bringing humid air masses from the Amazon Basin or the Pacific. The transitions between the different regimes are also coherent, representing transitions to and from similar regimes. A few negative and significant trends in the persistence of different regimes were detected, most likely linked to the absence of anthropogenic warming in the Antarctic as opposed to the Arctic. Finally, two of the regimes derived from surface wind speed exhibit a negative and significant trend in its frequency of occurrence, determining a precipitation decrease in the south of the study area (28–30°S), which can be compared with the Megadrought experienced in central Chile. ; The authors want to thank the support of the FONDECYT Project 11160059, the Climatology Group (2017 SGR 1362, Catalan Government), the Spanish Ministry of Economy and Competitiveness (MINECO) as part of the Juan de la Cierva - Incorporación grant (BOE-A-2010-3694), the New European Wind Atlas (NEWA) project (PCIN-2016-029), the Subseasonal to Seasonal for Energy (S2S4E) project (H2020-SC5-2016-2017), and the CLICES Project (CGL2017-83866-C3-2-R). The authors also acknowledge the s2d verification R-language-based software package developers, as this package was used for the data analysis and the visualization of the results presented in this work. ; Peer Reviewed ; Postprint (author's final draft)
Título del pre-print: Precipitation characterization of northern Chile using weather regimes ; Northern Chile is one of the most arid regions in the world, with precipitation mainly occurring during austral summer, between December and April. The aim of this study is to classify the main weather regimes derived from sea level pressure, surface wind speed, 500 or 250 hPa geopotential heights, in order to measure their influence on precipitation anomalies and determine if they can be considered sources of predictability of rainfall in this region. Four weather regimes were found to optimally describe atmospheric circulation in the study area during 1966-2015 and for each of the four levels described above. Using daily precipitation data from a network of 161 meteorological stations across the region, the rainfall anomalies associated with each weather regime were quantified. They are coherent with the direction of flow derived from pressure and geopotential anomalies, bringing humid air masses from the Amazon Basin or the Pacific. The transitions between the different regimes are also coherent, representing transitions to and from similar regimes. A few negative and significant trends in the persistence of different regimes were detected, most likely linked to the absence of anthropogenic warming in the Antarctic as opposed to the Arctic. Finally, two of the regimes derived from surface wind speed exhibit a negative and significant trend in its frequency of occurrence, determining a precipitation decrease in the south of the study area (28–30°S), which can be compared with the Megadrought experienced in central Chile. ; The authors want to thank the support of the FONDECYT Project 11160059 (Chilean Government), the Climatology Group (2017 SGR 1362, Catalan Government), the Spanish Ministry of Economy and Competitiveness (MINECO) as part of the Juan de la Cierva - Incorporación grant (BOE-A-2010-3694), the New European Wind Atlas (NEWA) project (PCIN-2016-029), the Subseasonal to Seasonal for Energy (S2S4E) project ...
Subseasonal predictions bridge the gap between medium-range weather forecasts and seasonal climate predictions. This time scale is crucial for operations and planning in many sectors such as energy and agriculture. For users to trust these predictions and efficiently make use of them in decision-making, the quality of predicted near-surface parameters needs to be systematically assessed. However, the method to follow in a probabilistic evaluation of subseasonal predictions is not trivial. This study aims to offer an illustration of the impact that the verification setup might have on the calculation of the skill scores, thus providing some guidelines for subseasonal forecast evaluation. For this, several forecast verification setups to calculate the fair ranked probability skill score for tercile categories have been designed. These setups use different number of samples to compute the fair RPSS as well as different ways to define the climatology, characterized by different time periods to average (week or month). These setups have been tested by evaluating 2-m temperature in ECMWF-Ext-ENS 20-yr hindcasts for all of the initializations in 2016 against the ERA-Interim reanalysis. Then, the implications on skill score values of each of the setups are analyzed. Results show that to obtain a robust skill score several start dates need to be employed. It is also shown that a constant monthly climatology over each calendar month may introduce spurious skill score associated with the seasonal cycle. A weekly climatology bears similar results to a monthly running-window climatology; however, the latter provides a better reference climatology when bias adjustment is applied. ; The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under Grants 7767874 (S2S4E) and 641811 (IMPREX). We acknowledge the ECMWF for producing the ERA-Interim reanalysis and ECMWF-Ext-ENS predictions and the WWRP/WCRP S2S Project for making ECMWF-Ext-ENS predictions available through its database (http://s2sprediction.net/). We acknowledge the use of the SpecsVerification (https://CRAN.R-project.org/package=SpecsVerification), s2dverification https://CRAN.R-project.org/package=s2dverification), and startR (https://CRAN.R-project.org/package=startR) R software packages. The authors thank Pierre-Antoine Bretonnière, Margarida Samsó, and Julia Giner for data downloading and processing and Nicolau Manubens, An Chi-Ho, Núria Pérez-Zanón, Javier Vegas, and Lluís Palma for technical support. ; Peer Reviewed ; Postprint (published version)
Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations. ; Spanish Government (Ministry of Economy and Competitiveness, MINECO) and FEDER Projects: CGL2014 52135-C3-3-R, ESP2017-89463-C3-3-R, CGL2014-59946-R, CGL2015-65569-R, CGL2015-64284-C2-2-R, CGL2015-64284-C2-1-R, CGL2016-78075-P, GL2008-02879/BTE, LEDDRA 243857, RECARE-FP7, CGL2017-83866-C3-1-R, and PCIN-2017-061/AEI. Dhais Peña-Angulo received a "Juan de la Cierva" postdoctoral contract (FJCI-2017-33652 Spanish Ministry of Economy and Competitiveness, MEC). Ana Lucia acknowledge the "Brigitte-Schlieben-Lange-Programm". The "Geoenvironmental Processes and Global Change" (E02_17R) was financed by the Aragón Government and the European Social Fund. José Andrés López-Tarazón acknowledges the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUS- Fluvial Dynamics Research Group). Artemi Cerdà thank the funding of the OCDE TAD/CRP JA00088807. José Martínez-Fernandez acknowledges the project Unidad de Excelencia CLU-2018-04 co-funded by FEDER and Castilla y León Government. Ane Zabaleta is supported by the Hydro-Environmental Processes consolidated research group (IT1029-16, Basque Government). This paper has the benefit of the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306). ; Peer Reviewed ; "Article signat per 78 autors/es: D. Peña-Angulo ,E. Nadal-Romero,J.C. González-Hidalgo ,J. Albaladejo ,V. Andreu ,H. Bahri,S. Bernal ,M. Biddoccu ,R. Bienes ,J. Campo ,M.A. Campo-Bescós ,A. Canatário-Duarte ,Y. Cantón 1,J. Casali ,V. Castillo, E. Cavallo ,A. Cerdà ,P. Cid ,N. Cortesi ,G. Desir, E. Díaz-Pereira,T. Espigares ,J. Estrany ,J. Farguell ,M. Fernández-Raga ,C.S. Ferreira ,V. Ferro, F. Gallart ,R. Giménez ,E. Gimeno ,J.A. Gómez , A. Gómez-Gutiérrez, H. Gómez-Macpherson,O. González-Pelayo,O. Kairis,G.P. Karatzas ,S. Keesstra ,S. Klotz ,C. Kosmas ,N. Lana-Renault,T. Lasanta ,J. Latron ,R. Lázaro ,Y. Le Bissonnais ,C. Le Bouteiller ,F. Licciardello ,J.A. López-Tarazón ,A. Lucía ,V.M. Marín-Moreno, C. Marín ,M.J. Marqués ,J. Martínez-Fernández ,M. Martínez-Mena ,L. Mateos ,N. Mathys ,L. Merino-Martín ,M. Moreno-de las Heras ,N. Moustakas ,J.M. Nicolau ,V. Pampalone , D. Raclot ,M.L. Rodríguez-Blanco ,J. Rodrigo-Comino ,A. Romero-Díaz ,J.D. Ruiz-Sinoga ,J.L. Rubio ,S. Schnabel ,J.M. Senciales-González ,A. Solé-Benet ,E.V. Taguas ,M.T. Taboada-Castro ,M.M. Taboada-Castro ,F. Todisco ,X. Úbeda ,E.A. Varouchakis ,L. Wittenberg ,A. Zabaleta andM. Zorn." ; Postprint (published version)
Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations. ; Spanish Government (Ministry of Economy and Competitiveness, MINECO) and FEDER Projects: CGL2014 52135-C3-3-R, ESP2017-89463-C3-3-R, CGL2014-59946-R, CGL2015-65569-R, CGL2015-64284-C2-2-R, CGL2015-64284-C2-1-R, CGL2016-78075-P, GL2008-02879/BTE, LEDDRA 243857, RECARE-FP7, CGL2017-83866-C3-1-R, and PCIN-2017-061/AEI. Dhais Peña-Angulo received a "Juan de la Cierva" postdoctoral contract (FJCI-2017-33652 Spanish Ministry of Economy and Competitiveness, MEC). Ana Lucia acknowledge the "Brigitte-Schlieben-Lange-Programm". The "Geoenvironmental Processes and Global Change" (E02_17R) was financed by the Aragón Government and the European Social Fund. José Andrés López-Tarazón acknowledges the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUS- Fluvial Dynamics Research Group). Artemi Cerdà thank the funding of the OCDE TAD/CRP JA00088807. José Martínez-Fernandez acknowledges the project Unidad de Excelencia CLU-2018-04 co-funded by FEDER and Castilla y León Government. Ane Zabaleta is supported by the Hydro-Environmental Processes consolidated research group (IT1029-16, Basque Government). This paper has the benefit of the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306).