Browsing by Person "Milovac, Josipa"

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The added value of simulated near-surface wind speed over the Alps from a km-scale multimodel ensemble
(2024) Molina, M. O.; Careto, J. M.; Gutiérrez, C.; Sánchez, E.; Goergen, K.; Sobolowski, S.; Coppola, E.; Pichelli, E.; Ban, N.; Belus̆ić, D.; Short, C.; Caillaud, C.; Dobler, A.; Hodnebrog, Ø.; Kartsios, S.; Lenderink, G.; de Vries, H.; Göktürk, O.; Milovac, Josipa; Feldmann, H.; Truhetz, H.; Demory, M. E.; Warrach-Sagi, Kirsten; Keuler, K.; Adinolfi, M.; Raffa, M.; Tölle, M.; Sieck, K.; Bastin, S.; Soares, P. M. M.; Molina, M. O.; Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Ed. C8 (3.26), 1749-016, Lisbon, Portugal; Careto, J. M.; Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Ed. C8 (3.26), 1749-016, Lisbon, Portugal; Gutiérrez, C.; Department of Physics and Mathematics, University of Alcalá, Alcalá de Henares, Madrid, Spain; Sánchez, E.; University of Castilla-La Mancha (UCLM), Faculty of Environmental Sciences and Biochemistry, Avenida Carlos III s/n, 45071, Toledo, Spain; Goergen, K.; Research Centre Juelich, Institute of Bio- and Geosciences (IBG-3, Agrosphere), 52425, Juelich, Germany; Sobolowski, S.; NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway; Coppola, E.; Earth System Physics Section, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy; Pichelli, E.; Earth System Physics Section, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy; Ban, N.; Department of Atmospheric and Cryospheric Sciences (ACINN), University of Innsbruck, Innsbruck, Austria; Belus̆ić, D.; Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden; Short, C.; Met Office Hadley Centre, Fitzroy Road, EX1 3PB, Exeter, UK; Caillaud, C.; CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France; Dobler, A.; Norwegian Meteorological Institute, Oslo, Norway; Hodnebrog, Ø.; Center for International Climate Research (CICERO), Oslo, Norway; Kartsios, S.; Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece; Lenderink, G.; Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands; de Vries, H.; Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands; Göktürk, O.; NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway; Milovac, J.; Meteorology Group, Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain; Feldmann, H.; Institute of Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Truhetz, H.; Wegener Center for Climate and Global Change, University of Graz, Graz, Austria; Demory, M. E.; Institute for Atmospheric and Climate Sciences, ETH Zürich, Zürich, Switzerland; Warrach-Sagi, K.; Institute of Physics and Meteorology, University of Hohenheim, Stuttgart, Germany; Keuler, K.; Chair of Atmospheric Processes Brandenburg University of Technology (BTU), Cottbus, Germany; Adinolfi, M.; Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici, Regional Model and Geo-Hydrological Impacts (REMHI) Division, Via Thomas Alva Edison, 81100, Caserta, Italy; Raffa, M.; Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici, Regional Model and Geo-Hydrological Impacts (REMHI) Division, Via Thomas Alva Edison, 81100, Caserta, Italy; Tölle, M.; Center for Environmental Systems Research (CESR), University of Kassel, Kassel, Germany; Sieck, K.; Climate Service Center Germany (GERICS), Helmholtz-Zentrum Hereon, 20095, Hamburg, Germany; Bastin, S.; LATMOS/IPSL, UVSQ Université Paris-Saclay, UPMC University, Paris, France; Soares, P. M. M.; Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Ed. C8 (3.26), 1749-016, Lisbon, Portugal
The advancement of computational resources has allowed researchers to run convection-permitting regional climate model (CPRCM) simulations. A pioneering effort promoting a multimodel ensemble of such simulations is the CORDEX Flagship Pilot Studies (FPS) on “Convective Phenomena over Europe and the Mediterranean” over an extended Alps region. In this study, the Distribution Added Value metric is used to determine the improvement of the representation of all available FPS hindcast simulations for the daily mean near-surface wind speed. The analysis is performed on normalized empirical probability distributions and considers station observation data as the reference. The use of a normalized metric allows for spatial comparison among the different regions (coast and inland), altitudes and seasons. This approach permits a direct assessment of the added value between the CPRCM simulations against their global driving reanalysis (ERA-Interim) and respective coarser resolution regional model counterparts. In general, the results show that CPRCMs add value to their global driving reanalysis or forcing regional model, due to better-resolved topography or through better representation of ocean-land contrasts. However, the nature and magnitude of the improvement in the wind speed representation vary depending on the model, the season, the altitude, or the region. Among seasons, the improvement is usually larger in summer than winter. CPRCMs generally display gains at low and medium-range altitudes. In addition, despite some shortcomings in comparison to ERA-Interim, which can be attributed to the assimilation of wind observations on the coast, the CPRCMs outperform the coarser regional climate models, both along the coast and inland.
Studies of soil-vegetation-atmosphere feedback processes with WRF on the convection permitting scale
(2017) Milovac, Josipa; Wulfmeyer, Volker
Land system models which can incorporate land-atmosphere and human-environment interactions are vital for reliable climate projections in heterogeneous agricultural landscapes. At resolutions fine enough to resolve detailed land use, models need a sophisticated representation of planetary boundary layer (PBL) and land surface processes in order to predict changes in key quantities like precipitation or temperatures. Assessment of turbulence schemes and land surface models (LSM) is fundamental therefore not only to advance model development, but also to understand important phenomena like feedbacks within the soil-vegetation-atmosphere (SVA) continuum. Up until now however, a lack of appropriate observations has impeded any comprehensive assessments. Here, through comparisons with so far unique profile measurements, the study investigates the impact of using different PBL schemes and LSMs, and explores how SVA feedbacks are simulated by the model. Using the Weather Research and Forecasting (WRF) model, a six member ensemble was run, at a convection permitting resolution, with varying combinations of LSMs (NOAH and NOAH-MP) and PBL schemes (two local and two non-local approaches). The analysis was performed for two case studies – a dry and a convective weather situation – in three different locations in Germany. During the dry case, key convective PBL (CBL) features were analysed, and the simulations were compared with high resolution water vapour differential absorption lidar measurements. For the convective case, the focus was on exploring the model representation of the pre-convective environment and the ensuing convection and precipitation. In both cases, the nature of the simulated SVA feedback processes was assessed through an innovative “mixing diagram” approach. Results show that the nonlocal PBL schemes produce a drier and higher CBL than the local schemes. These results are sensitive to parameters calculated in the surface layer schemes, which are themselves often paired with PBL schemes. Furthermore, the NOAH‑MP LSM produces drier atmospheric conditions than NOAH, with a difference in mixing ratio profiles ranging up to 1.4 gkg-1. These variations are more pronounced in the upper CBL than close to the ground. The mixing diagrams indicate that these deviations are mainly related to entrainment fluxes. In the dry case, NOAH-MP’s dry air entrainment is up to 6 times higher than with NOAH, while in the convective case the difference is not as pronounced (up to 1.5 higher with NOAH-MP). This suggests that the difference in the simulation of the CBL between the two LSMs is strongly linked to the surface energy partitioning – the higher the Bowen ratio, the greater the difference between the LSMs. Thus, WRF appears to be more sensitive to the choice of LSM at higher Bowen ratios. NOAH and NOAH-MP exhibit marked differences in representing atmospheric variables such as moisture. Those differences are not constrained to the lower atmosphere close to the land surface, but extended to the lower troposphere. The variations in free tropospheric moisture between the LSMs strongly affects the nature of the simulated convection, and associated precipitation. The degree of sensitivity of the spatial variability and amount of the precipitation with respect to the selection of LSM and PBL scheme shows a strong dependence on the analysed region. A distinct finding of this thesis is the greater sensitivity of WRF with respect to the PBL development to the selection of the LSM, than to the PBL scheme. Furthermore, the impact of this sensitivity is not constrained to the lower CBL, but extends up to the interfacial layer and the lower troposphere - for both dry and convective weather conditions. On the other hand, it is clear that the simulated coupling strength between the land surface and atmosphere is very sensitive to the surface Bowen ratio. The synergies between high resolution measurements and model simulations, with an advanced representation of the land surface processes, will facilitate not only further development of parameterization schemes, but also an improvement in our understanding of land-atmosphere interactions.