WRF4G: WRF experiment management made simple

his work presents a framework, WRF4G, to manage the experiment workflow of the Weather Research and Forecasting (WRF) modelling system. WRF4G provides a flexible design, execution and monitoring for a general class of scientific experiments. It has been designed with the aim of facilitating the management and reproducibility of complex experiments. Furthermore, the concepts behind the design of this framework can be straightforwardly extended to other modelsThis work has been supported by the Spanish National R&D Plan under projects WRF4G (CGL2011-28864, co-funded by the European Regional Development Fund –ERDF–) and CORWES (CGL2010-22158-C02-01) and the IS-ENES2 project from the 7FP of the European Commission (grant agreement no. 312979). C. Blanco acknowledges financial support 5 from programa de Personal Investigador en Formación Predoctoral from Universidad de Cantabria, co-funded by the regional government of Cantabria. The authors are thankful to the developers of third party software (e.g. GridWay, WRFV3, python and NetCDF), which was intensively used in this work

Observed and Projected Hydroclimate Changes in the Andes

The Andes is the most biodiverse region across the globe. In addition, some of the largest urban areas in South America are located within this region. Therefore, ecosystems and human population are affected by hydroclimate changes reported at global, regional and local scales. This paper summarizes progress of knowledge about long-term trends observed during the last two millennia over the entire Andes, with more detail for the period since the second half of the 20th century, and presents a synthesis of climate change projections by the end of the 21st century. In particular, this paper focuses on temperature, precipitation and surface runoff in the Andes. Changes in the Andean cryosphere are not included here since this particular topic is discussed in other paper in this Frontiers special issue, and elsewhere (e.g. IPCC,2019b). While previous works have reviewed the hydroclimate of South America and particular sectors (i.e., Amazon and La Plata basins, the Altiplano, Northern South America, etc.) this review includes for the first time the entire Andes region, considering all latitudinal ranges: tropical (North of 27°S), subtropical (27°S−37°S) and extratropical (South of 37°S). This paper provides a comprehensive view of past and recent changes, as well as available climate change projections, over the entire Andean range. From this review, the main knowledge gaps are highlighted and urgent research necessities in order to provide more mechanistic understanding of hydroclimate changes in the Andes and more confident projections of its possible changes in association with global climate change.Fil: Pabón Caicedo, José Daniel. Universidad Nacional de Colombia; ColombiaFil: Arias, Paola A.. Universidad de Antioquia; ColombiaFil: Carril, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Espinoza, Jhan Carlo. Universite Grenoble Alpes; FranciaFil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Goubanova, Katerina. Centro de Estudios Avanzados en Zonas Áridas; ChileFil: Lavado Casimiro, Waldo. No especifíca;Fil: Masiokas, Mariano Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Solman, Silvina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

The first multi-model ensemble of regional climate simulations at kilometer-scale resolution, part I: Evaluation of precipitation

Here we present the first multi-model ensemble of regional climate simulations at kilometer-scale horizontal grid spacing over a decade long period. A total of 23 simulations run with a horizontal grid spacing of ∼ 3 km, driven by ERA-Interim reanalysis, and performed by 22 European research groups are analysed. Six different regional climate models (RCMs) are represented in the ensemble. The simulations are compared against available high-resolution precipitation observations and coarse resolution (∼ 12 km) RCMs with parameterized convection. The model simulations and observations are compared with respect to mean precipitation, precipitation intensity and frequency, and heavy precipitation on daily and hourly timescales in different seasons. The results show that kilometer-scale models produce a more realistic representation of precipitation than the coarse resolution RCMs. The most significant improvements are found for heavy precipitation and precipitation frequency on both daily and hourly time scales in the summer season. In general, kilometer-scale models tend to produce more intense precipitation and reduced wet-hour frequency compared to coarse resolution models. On average, the multi-model mean shows a reduction of bias from ∼ −40% at 12 km to ∼ −3% at 3 km for heavy hourly precipitation in summer. Furthermore, the uncertainty ranges i.e. the variability between the models for wet hour frequency is reduced by half with the use of kilometer-scale models. Although differences between the model simulations at the kilometer-scale and observations still exist, it is evident that these simulations are superior to the coarse-resolution RCM simulations in the representing precipitation in the present-day climate, and thus offer a promising way forward for investigations of climate and climate change at local to regional scales.Fil: Ban, Nikolina. Universidad de Innsbruck; AustriaFil: Caillaud, Cécile. Université de Toulouse; FranciaFil: Coppola, Erika. The Abdus Salam. International Centre for Theoretical Physics; Italia. The Abdus Salam; ItaliaFil: Pichelli, Emanuela. The Abdus Salam; Italia. The Abdus Salam. International Centre for Theoretical Physics; ItaliaFil: Sobolowski, Stefan. Norwegian Research Centre; NoruegaFil: Adinolfi, Marianna. Fondazione Centro Euro-Mediterraneo sui cambiamenti climatici; ItaliaFil: Ahrens, Bodo. Goethe Universitat Frankfurt; AlemaniaFil: Alias, Antoinette. Université de Toulouse; FranciaFil: Anders, Ivonne. German Climate Computing Center; AlemaniaFil: Bastin, Sophie. Universite Paris-Saclay;Fil: Belušić, Danijel. Swedish Meteorological and Hydrological Institute; SuizaFil: Berthou, Ségolène. Met Office Hadley Centre; Reino UnidoFil: Brisson, Erwan. Université de Toulouse; FranciaFil: Cardoso, Rita M.. Universidade Nova de Lisboa; PortugalFil: Chan, Steven C.. University of Newcastle; Reino UnidoFil: Christensen, Ole Bøssing. Danish Meteorological Institute; DinamarcaFil: Fernández, Jesús. Universidad de Cantabria; EspañaFil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Instituto Franco-Argentino sobre Estudios del Clima y sus Impactos; ArgentinaFil: Frisius, Thomas. Helmholtz Gemeinschaft; AlemaniaFil: Gaparac, Goran. Croatia Control Ltd.; CroaciaFil: Giorgi, Filippo. The Abdus Salam. International Centre for Theoretical Physics; Italia. The Abdus Salam; ItaliaFil: Goergen, Klaus. Centre for High-Performance Scientific Computing in Terrestrial Systems; Alemania. Helmholtz Gemeinschaft. Forschungszentrum Jülich; AlemaniaFil: Haugen, Jan Erik. Norwegian Meteorological Institute; NoruegaFil: Hodnebrog, Øivind. Center for International Climate and Environmental Research-Oslo; NoruegaFil: Kartsios, Stergios. Aristotle University Of Thessaloniki; GreciaFil: Katragkou, Eleni. Aristotle University Of Thessaloniki; GreciaFil: Kendon, Elizabeth J.. Met Office Hadley Centre; Reino UnidoFil: Keuler, Klaus. Brandenburg University of Technology Cottbus-Senftenberg; AlemaniaFil: Lavin Gullon, Alvaro. Universidad de Cantabria; EspañaFil: Lenderink, Geert. Royal Netherlands Meteorological Institute; Países Bajo

Numerical study of intense cyclogenesis events in the Mediterranean basin 

[cat] S'han estudiat diverses ciclogènesis mediterrànies mitjançant el model atmosfèric MM5, la inversió de vorticitat potencial per peces i la tècnica de la separació de factors. Els resultats mostren com a agents per a una ciclogènesi intensa: anomalia a nivells alts; confrontació de masses d'aire càlides i fredes a nivells baixos, desenvolupament baroclí; processos diabàtics; el mar; efectes topogràfics; baixa tèrmica; fluxes de calor superficials i les condicions atmosfèriques de l'entorn. S'ha verificat el comportament quasi-tropical dels medicans, com a mescla de la interació mar-aire i l'existència d'una anomalia de nivells alts, amb una evolució diferent a la dels huracans. S'ha observat l'impacte en les simulacions de medicanes d'assimilar informació de satèl·lit i de descàrregues elèctriques. S'han desenvolupat millores o nous usos d'algunes tècniques emprades: quantificació energètica de la modificació derivada de la inversió de vorticitat potencial, l'ús lagrangià de la separació de factors, modificacions a parts del MM5

Medicanes as subtropical cyclones: the December 2005 case from the perspective of surface pressure tendency diagnostics and atmospheric water budget

Mediterranean cyclones with tropical-like characteristics such as spiral cloud coverage and a central cloud-free “eye” are referred to as medicanes. These systems have been analyzed due to their relation with high-impact weather. In previous studies, the identification of medicanes has been typically performed subjectively, using satellite pictures, but also objectively through three-dimensional diagnosis of a warm core and an axisymmetric structure. Despite the presence of these characteristics, it is still unclear if medicanes show dynamical similarities with tropical cyclones. We analyse the (thermo-)dynamics of a recognized medicane that occurred in December 2005 by applying different diagnostics to a high-resolution simulation. These diagnostics are focused on the intensification, dynamical structure and water budget of this representative case, aiming to highlight extratropical and tropical cyclone characteristics. Three stages in the medicane life cycle are identified. In stage I, a potential vorticity (PV) streamer reaches the Mediterranean, triggering deep convection and deepening the medicane's central surface pressure due to diabatic heating. When the lowest central pressure is reached (stage II), the medicane presents a warm core and an axisymmetric structure. However, convection is rather weak and the PV streamer evolves into a cut-off system which contributes to the deepening of the medicane's surface pressure. Finally, stage III corresponds to the decay phase where the medicane tends to weaken and lose its axisymmetric structure. Our results highlight the detrimental role of deep convection prior to the mature stage of the medicane, as well as the possibility of positive or negative feedback of upper-tropospheric dynamics on the central surface pressure. In addition, we show that the medicane warm core might be achieved due to front seclusion, while the “eye” formation is associated with dry air intrusions. Our analysis suggests that medicanes are hybrid systems combining characteristics of both tropical and extratropical cyclones and thus they plausibly correspond to subtropical cyclones.Fil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Flaounas, E.. National Observatory of Athens; Greci

Heavy rainfall in Mediterranean cyclones, Part II: Water budget, precipitation efficiency and remote water sources

In this study, we use convection-permitting high resolution (3 km) simulations to quantify and analyse the water budget, precipitation efficiency and water sources of 100 intense Mediterranean cyclones. To this end, we calculate the water content, advection and microphysical processes of water vapour and rain water by implementing new diagnostics to the Weather Research and Forecasting (WRF) model. The 100 intense cyclones have been randomly selected from a 500 intense cyclones dataset, identified and tracked in an 11-year time period in part I of this study. Results are presented in a composite approach showing that most rainfall takes place to the north-east side of the cyclones, close to their centre. Rainfall location is concomitant to the area of horizontal moisture flux convergence and is quasi-equal to the amount of water vapour loss due to microphysical processes. Similar results were found regardless if cyclones produce high or low rainfall amounts. Vertical profiles of the water budget terms revealed deeper clouds for the cyclones producing high rainfall, consistent with higher values of vertical advection of both water vapour and rain water. Finally, cyclones were analysed with respect to their precipitation efficiency, i.e. the ratio between the rainwater produced in an atmospheric column and the consequent rainfall, and showed that cyclones tend to be more efficient when their rainfall production takes place over land. Therefore, there is a complex relation between water vapour advection, precipitation efficiency and rainfall which is discussed through the comparison of two tropical-like cyclones with two cyclones that produced low rainfall amounts. Finally, our analysis is complemented by applying a Lagrangian approach to all 100 cyclones in order to quantify the water vapour source regions that contribute to the cyclones’ rainfall due to local surface evaporation. Results showed that these regions are located over both the Atlantic and the Mediterranean, however we show that cyclones producing high rainfall are related with higher water transport from both the subtropical Atlantic and the Mediterranean Sea.Fil: Flaounas, Emmanouil. National Observatory; GreciaFil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Lagouvardos, Konstantinos. National Observatory; GreciaFil: Kotroni, Vassiliki. National Obsevatory ; Greci

The role of atmospheric forcings and WRF physical set-up on convective initiation over Córdoba, Argentina

The accurate determination of the location and timing of convective initiation (CI) is a crucial aspect of forecasting and high impact weather warning systems associated with deep convection. Central Argentina, particularly the Sierras de Córdoba (SDC), is characterized by the regular occurrence of deep convective cells that reach supercell characteristics producing large hail and occasionally tornadoes. In order to analyze the sensitivity of the CI over SDC, an ensemble of 12 simulations with the WRF model at convection-permitting resolution (3 km.) was carried out to study a marginal supercell initiated on October 17, 2017 at the SDC foothills. The ensemble was built using 3 different microphysics (MP) parameterizations (WSM6, Thompson and Morrison) and 2 planetary boundary layer (PBL) parameterizations (Yonsei University and Mellor Yamada Janjic). Also, the sensitivity of initial and boundary conditions is considered by forcing the model with 2 different global analyses: the European Centre for Medium-Range Weather Forecast (ECMWF) model, and the Global Data Assimilation System (GDAS). The two different forcing data show low-level moisture differences, which later modulate the life-cycle of the simulated cells. A tracking algorithm was used to capture their life-cycle, and CI was detected at both the hills and the plains. Simulations forced with ECMWF analyses tend to show better results with characteristics closer to the ones observed including: initiation over the eastward slope of SDC, stronger cells and slow propagation. Among all simulations analyzed, the best performance was obtained with the combination of Thompson MP and Yonsei University PBL schemes.Fil: Alvarez Imaz, María de Los Milagros. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Salio, Paola Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Instituto Franco-argentino sobre Estudios del Clima y sus Impactos; ArgentinaFil: Dillon, María Eugenia. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Instituto Franco-argentino sobre Estudios del Clima y sus Impactos; Argentin

The impact of soil moisture–atmosphere coupling on daily maximum surface temperatures in Southeastern South America

Based on a series of experiments conducted by two regional climate models (RCA4 and LMDZ) with and without soil moisture-atmosphere coupling, we investigate the role of soil moisture on the occurrence of surface air temperature extremes and its persistence in Southeastern South America. Our analysis reveals that both factors, soil moisture-atmosphere coupling and relatively drier soil conditions, enhance the temperature extremes. In addition, the existence of soil-atmosphere coupling and the associated soil moisture variability is crucial for the development of the extremes in SESA. The key role of soil-atmosphere coupling is also reflected in the intrinsic persistence of hot days, which is greater in simulations with interactive soil moisture than in those with prescribed soil conditions. In the absence of soil-atmosphere coupling, the imprint of the anomalous dry (and also wet) soil conditions on the intensity and persistence of hot days is weaker.Fil: Coronato, Tanea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Carril, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Zaninelli, Pablo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Giles, Julián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Ruscica, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Falco, Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Sörensson, Anna. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Li, Laurent Z. X.. Laboratoire de Meteorologie Dynamique; FranciaFil: Menendez, Claudio Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentin

Consistency of climate change projections from multiple global and regional model intercomparison projects

We present an unprecedented ensemble of 196 future climate projections arising from different global and regional model intercomparison projects (MIPs): CMIP3, CMIP5, ENSEMBLES, ESCENA, EURO- and Med-CORDEX. This multi-MIP ensemble includes all regional climate model (RCM) projections publicly available to date, along with their driving global climate models (GCMs). We illustrate consistent and conflicting messages using continental Spain and the Balearic Islands as target region. The study considers near future (2021–2050) changes and their dependence on several uncertainty sources sampled in the multi-MIP ensemble: GCM, future scenario, internal variability, RCM, and spatial resolution. This initial work focuses on mean seasonal precipitation and temperature changes. The results show that the potential GCM–RCM combinations have been explored very unevenly, with favoured GCMs and large ensembles of a few RCMs that do not respond to any ensemble design. Therefore, the grand-ensemble is weighted towards a few models. The selection of a balanced, credible sub-ensemble is challenged in this study by illustrating several conflicting responses between the RCM and its driving GCM and among different RCMs. Sub-ensembles from different initiatives are dominated by different uncertainty sources, being the driving GCM the main contributor to uncertainty in the grand-ensemble. For this analysis of the near future changes, the emission scenario does not lead to a strong uncertainty. Despite the extra computational effort, for mean seasonal changes, the increase in resolution does not lead to important changes.Fil: Fernández, J.. Universidad de Cantabria. Facultad de Ciencias. Departamento de Matemáticas, Estadística y Computación; EspañaFil: Frías, M. D.. Universidad de Cantabria. Facultad de Ciencias. Departamento de Matemáticas, Estadística y Computación; EspañaFil: Cabos, W. D.. Universidad de Alcalá. Facultad de Ciencias; EspañaFil: Cofiño, A. S.. Universidad de Cantabria. Facultad de Ciencias. Departamento de Matemáticas, Estadística y Computación; EspañaFil: Domínguez, M.. Universidad de Castilla-La Mancha. Facultad de Ciencias Ambientales; EspañaFil: Fita Borrell, Lluís. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Gaertner, M. A.. Universidad de Castilla-La Mancha. Facultad de Ciencias Ambientales; EspañaFil: García Díez, M.. Predictia Intelligent Data Solution; EspañaFil: Gutiérrez, J. M.. Universidad de Cantabria; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Jiménez Guerrero, P.. Universidad de Murcia; EspañaFil: Liguori, Adela Gabriela. Universidad de Alcalá. Facultad de Ciencias; EspañaFil: Montávez, J. P.. Universidad de Murcia; EspañaFil: Romera, R.. Universidad de Castilla-La Mancha. Facultad de Ciencias Ambientales; EspañaFil: Sánchez, E.. Universidad de Castilla-La Mancha. Facultad de Ciencias Ambientales; Españ

Internal variability versus multi-physics uncertainty in a regional climate model

In a recent study, Coppola et al. assessed the ability of an ensemble of convection-permitting models (CPM) to simulate deep convection using three case studies. The ensemble exhibited strong discrepancies between models, which were attributed to various factors. In order to shed some light on the issue, we quantify in this article the uncertainty associated to different physical parameterizations from that of using different initial conditions, often referred to as the internal variability. For this purpose, we establish a framework to quantify both signals and we compare them for upper atmospheric circulation and near-surface variables. The analysis is carried out in the context of the CORDEX Flagship Pilot Study on Convective phenomena at high resolution over Europe and the Mediterranean, in which the intermediate RCM WRF simulations that serve to drive the CPM are run several times with different parameterizations. For atmospheric circulation (geopotential height), the sensitivity induced by multi?physics and the internal variability show comparable magnitudes and a similar spatial distribution pattern. For 2-m temperature and 10-m wind, the simulations with different parameterizations show larger differences than those launched with different initial conditions. The systematic effect over one year shows distinct patterns for the multi-physics and the internal variability. Therefore, the general lesson of this study is that internal variability should be analysed in order to properly distinguish the impact of other sources of uncertainty, especially for short-term sensitivity simulations.This work is partially funded by the Spanish government through grant BES-2016-078158 and MINECO/ FEDER co-funded projects INSIGNIA (CGL2016-79210-R) and MULTI-SDM (CGL2015-66583-R). Universidad de Cantabria simulations have been carried out on the Altamira Supercomputer at the Instituto de F´ısica de Cantabria (IFCA-CSIC), member of the Spanish Supercomputing Network. EK and SK acknowledge the support of the Greek Research and Technology Network (GRNET) High Performance Computing (HPC) infrastructure for providing the computational resources of AUTH-simulations (under project ID pr003005) and the AUTH Scientific Computing Center for technical support. IPSL acknowledges the support from the EUCP project, funded by the European Union under H2020 Grant Agreement 776613, and from the IPSL mesocenter ESPRI facility which is supported by CNRS, UPMC, Labex L-IPSL, CNES and Ecole Polytechnique. IPSL simulations were granted access to the HPC resources of TGCC 19 under the allocation A0050106877 made by GENCI. The computational resources for NORCE/BCCR were provided by UNINETT Sigma2 (NN9280K, NS9001K), with funding from the Research Council of Norway’s support for the strategic project on climate services. FZJ gratefully acknowledges the computing time granted by the John von Neumann Institute for Computing (NIC) and JARA-HPC provided on the supercomputer JURECA at J¨ulich Supercomputing Centre (JSC). We acknowledge the E-OBS dataset from the EU-FP6 project UERRA (https://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://eca.knmi.nl)