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Kupiainen, Marco
Publications (4 of 4) Show all publications
Nikulin, G., Lennard, C., Dosio, A., Kjellström, E., Chen, Y., Haensler, A., . . . Somot, S. (2018). The effects of 1.5 and 2 degrees of global warming on Africa in the CORDEX ensemble. Environmental Research Letters, 13(6), Article ID 065003.
Open this publication in new window or tab >>The effects of 1.5 and 2 degrees of global warming on Africa in the CORDEX ensemble
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2018 (English)In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065003Article in journal (Refereed) Published
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-4700 (URN)10.1088/1748-9326/aab1b1 (DOI)000433551600002 ()
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-06-19Bibliographically approved
Linders, V., Kupiainen, M. & Nordstrom, J. (2017). Summation-by-Parts operators with minimal dispersion error for coarse grid flow calculations. Journal of Computational Physics, 340, 160-176
Open this publication in new window or tab >>Summation-by-Parts operators with minimal dispersion error for coarse grid flow calculations
2017 (English)In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 340, p. 160-176Article in journal (Refereed) Published
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-4110 (URN)10.1016/j.jcp.2017.03.039 (DOI)000401137900009 ()
Available from: 2017-06-14 Created: 2017-06-14 Last updated: 2017-08-07Bibliographically approved
Strandberg, G., Bärring, L., Hansson, U., Jansson, C., Jones, C., Kjellström, E., . . . Ullerstig, A. (2015). CORDEX scenarios for Europe from the Rossby Centre regional climate model RCA4. SMHI
Open this publication in new window or tab >>CORDEX scenarios for Europe from the Rossby Centre regional climate model RCA4
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2015 (English)Report (Other academic)
Abstract [sv]

Denna rapport dokumenterar klimatmodellsimuleringar på 50 km horisontell upplösning över Europa med Rossby Centres regionala atmosfärsmodell (RCA4) gjorda inom projektet Coordinated Regional Downscaling Experiment (CORDEX) för i) ERAInterim-drivna (ERAINT) simuleringar för att utvärdera förmågan hos RCA4 att simuleraden senaste tidens klimat, ii) historiska simuleringar av de senaste årtiondena med drivning från nio olika globala klimatmodeller (GCM:er) och iii) framtidsscenarierna RCP 4,5 och RCP 8,5 drivna med samma GCM:er. Dessa simuleringar representerar en delmängd av alla CORDEX-simuleringar producerade vid Rossby Centre och en allmän slutsats dragen vid Rossby Centre är att en sådan ensemble inte varit möjlig utan att först etablera den effektiva produktionskedja som beskrivs här. Första delen av rapporten dokumenterar RCA4 och dess förmåga i en simulering där ERAINT skalades ner. RCA4 återskapar till stor del den storskaliga cirkulationen från ERAINT, men några lokala avvikelser förekommer. I allmänhet simuleras säsongscykler för temperatur och nederbörd i överensstämmelse med observationer. Några avvikelser finns, som för mycket nederbörd i norra Europa och för lite i södra. På vintern är det även för mycket nederbörd i östra Europa. Temperaturen är i allmänhet underskattad i norra Europa och i medelhavsområdet på vintern, medan för höga temperaturer ges i sydöstra Europa på vintern och i medelhavsområdet på sommaren. RCA4 presterar i allmänhet bra i simuleringar av den senaste tidens klimat med randvillkor från GCM:er. En stor del av det simulerade klimatet i RCA4 kan tillskrivas den drivande GCM:en, men RCA4 skapar sitt eget klimat inuti modelldomänen och lägger till detaljer på grund av högre upplösning. Alla nio nedskalade GCM:er har gemensamma problem i representationen av den storskaliga cirkulationen på vintern. Denna egenskap förs vidare till RCA4. Avvikelserna i storskalig cirkulation medför avvikelser i temperatur och nederbörd i RCA4. Klimatförändringssignalen som den simuleras av RCA4-ensembler enligt RCP 4,5 och RCP 8,5 är mycket lika tidigare resultat. I både scenario RCP 4,5 och RCP 8,5 beräknas Europa bli varmare i framtiden. På vintern är uppvärmningen störst i norra Europa, och på sommaren i södra Europa. Den högsta dygnsmedeltemperaturen på sommaren ökar på ungefär samma sätt som sommartemperaturen, men något mer i södra Europa. Den lägsta dygnsmedeltemperaturen på vintern i norra Europa är den temperatur som förändras mest. Nederbörden beräknas öka under alla årstider i norra Europa och minska i södra Europa. Den största dygnsnederbörden (och per sjudagarsperiod) beräknas öka i nästan hela Europa och i alla årstider. Samtidigt beräknas den längsta perioden utan nederbörd att bli längre i södra Europa. I allmänhet förutses små förändringar i medelvindhastighet. Det finns emellertid områden med signifikanta förändringar i vind. Att använda ensembler är ett sätt att beskriva osäkerheterna i scenarierna, men det finns andra möjliga ensembler som använder andra modeller och som skulle ge andra resultat. Ändå anses den ensemble som används här vara tillräckligt lik dessa andra ensembler för att vara representativ för den hela mängden GCM:er. Dynamisk nedskalning med RCA4 förändrar klimatförändringssignalen, och spridningen i ensemblen minskar ibland, men ensemblen med nio RCA4 simuleringar med olika GCM:er anses vara representativ för den hela ensemblen. Alla scenarier är överens om mönstret på klimatförändringen, men storleken på förändringen bestäms av valet av scenario. Den relativa betydelsen av valet av scenario ökar med tiden.

Abstract [en]

This report documents Coordinated Regional Downscaling Experiment (CORDEX) climate model simulations at 50 km horizontal resolution over Europe with the Rossby Centre regional atmospheric model (RCA4) for i) a ERA-Interim-driven (ERAINT) simulation used to evaluate model performance in the recent past climate, ii) historical simulations of the recent decades with forcing from nine different global climate models (GCMs) and iii) future scenarios RCP 4.5 and RCP 8.5 forced by the same nine different GCMs. Those simulations represent a subset of all CORDEX simulations produced at the Rossby Centre and a general conclusion drawn at the Rossby Centre is that such large ensembles could not have been produced without the establishment of an efficient production chain as outlined here. The first part of this report documents RCA4 and its performance in a perfect boundary simulation where ERAINT was downscaled. RCA4 is to a large extent replicating the large-scale circulation in ERAINT, but some local biases in mean sea level pressure appear. In general the seasonal cycles of temperature and precipitation are simulated in relatively close agreement to observations. Some biases occur, such as too much precipitation in northern Europe and too little in the south. In winter, there is also too much precipitation in eastern Europe. Temperatures are generally biased low in northern Europe and in the Mediterranean region in winter while overestimated temperatures are seen in southeastern Europe in winter and in the Mediterranean area in summer. RCA4 performs generally well when simulating the recent past climate taking boundary conditions from the GCMs. A large part of the RCA4 simulated climate is attributed to the driving GCMs, but RCA4 creates its own climate inside the model domain and adds details due to higher resolution. All nine downscaled GCMs share problems in their representation of the large-scale circulation in winter. This feature is inherited in RCA4. The biases in large-scale circulation induce some biases in temperature and precipitation in RCA4. The climate change signal in the RCP 4.5 and RCP 8.5 ensembles simulated by RCA4 is very similar to what has been presented previously. Both scenarios RCP 4.5 and RCP 8.5 project Europe to be warmer in the future. In winter the warming is largest in northern Europe and in summer in southern Europe. The summer maximum daily temperature increases in a way similar to summer temperature, but somewhat more in southern Europe. The winter minimum daily temperature in northern Europe is the temperature that changes the most. Precipitation is projected to increase in all seasons in northern Europe and decrease in southern Europe. The largest amount of rainfall per day (and per seven day period) is projected to increase in almost all of Europe and in all seasons. At the same time the longest period without precipitation is projected to be longer in southern Europe. Small changes in mean wind speed are generally projected. There are, however, regions with significant changes in wind. The ensemble approach is a way to describe the uncertainties in the scenarios, but there are other possible ensembles using other models which would give other results. Still, the ensemble used here is found to be similar enough to these other possible ensembles to be representative of the whole set of GCMs. Dynamical downscaling using RCA4 changes the climate change signal, and the ensemble spread is sometimes reduced, but the ensemble of nine RCA4 simulations, using different GCMs, is considered to be representative of the full ensemble. All scenarios agree on a climate change pattern; the amplitude of the change is determined by the choice of scenario. The relative importance of the chosen scenario increases with time.

Place, publisher, year, edition, pages
SMHI, 2015. p. 75
Series
RMK: Report Meteorology and Climatology, ISSN 0347-2116 ; 116
Identifiers
urn:nbn:se:smhi:diva-2839 (URN)Meteorologi, Klimat, Rapporter, Serie RMK (Local ID)Meteorologi, Klimat, Rapporter, Serie RMK (Archive number)Meteorologi, Klimat, Rapporter, Serie RMK (OAI)
Available from: 2015-06-16 Created: 2016-07-08 Last updated: 2016-07-08Bibliographically approved
Samuelsson, P., Gollvik, S., Kupiainen, M., Kourzeneva, E. & van de Berg, W. J. (2015). The surface processes of the Rossby Centre regional atmospheric climate model (RCA4). SMHI
Open this publication in new window or tab >>The surface processes of the Rossby Centre regional atmospheric climate model (RCA4)
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2015 (English)Report (Other academic)
Abstract [en]

This report describes the physical processes as part of the surface scheme in the Rossby Centre Regional Atmospheric Climate Model (RCA4). Or more strictly for the version used for the CORDEX downscalings with RCA4. The most important aspects of the surface scheme that are changed with respect to RCA3 are that (i) a new physiography data base is used, (ii) the number of soil layers with respect to soil moisture are increased from two to three and there is also separate soil columns with respect to soil water under forest and open land, respectively, (iii) an exponential root distribution is used, (iv) the density of organic carbon is used to modify soil properties, (v) the prognostic snow albedo is modified to perform better in cold-climate conditions, (vi) Flake is introduced as lake model and lake depth is defined from a global lake-depth data base, (vii) the dynamic vegetation model LPJ-GUESS is introduced for vegetation-climate feedback studies.

Place, publisher, year, edition, pages
SMHI, 2015. p. 42
Series
Meteorology, ISSN 0283-7730 ; 157
National Category
Meteorology and Atmospheric Sciences
Research subject
Meteorology
Identifiers
urn:nbn:se:smhi:diva-2840 (URN)Hydrologi, Rapporter, Serie Hydrologi (Local ID)Hydrologi, Rapporter, Serie Hydrologi (Archive number)Hydrologi, Rapporter, Serie Hydrologi (OAI)
Available from: 2015-06-03 Created: 2016-07-08 Last updated: 2018-09-18Bibliographically approved
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