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  • 301.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluation and future projections of temperature, precipitation and wind extremes over Europe in an ensemble of regional climate simulations2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 41-55Article in journal (Refereed)
  • 302.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Uncertainties in the projected climate changes of wind extremes over the Baltic region2010Conference paper (Other academic)
  • 303.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Lennard, Chris
    Dosio, Alessandro
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Chen, Youmin
    Haensler, Andreas
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Laprise, Rene
    Mariotti, Laura
    Maule, Cathrine Fox
    van Meijgaard, Erik
    Panitz, Hans-Juergen
    Scinocca, John F.
    Somot, Samuel
    The effects of 1.5 and 2 degrees of global warming on Africa in the CORDEX ensemble2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065003Article in journal (Refereed)
  • 304.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Lott, F.
    On the time-scales of the downward propagation and of the tropospheric planetary wave response to the stratospheric circulation2010In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 28, no 2, p. 339-351Article in journal (Refereed)
    Abstract [en]

    Three datasets (the NCEP-NCAR reanalysis, the ERA-40 reanalysis and the LMDz-GCM), are used to analyze the relationships between large-scale dynamics of the stratosphere and the tropospheric planetary waves during the Northern Hemisphere (NH) winter. First, a cross-spectral analysis clarifies the time scales at which downward propagation of stratospheric anomalies occurs in the low-frequency band (that is at periods longer than 50 days). At these periods the strength of the polar vortex, measured by the 20-hPa Northern Annular Mode (NAM) index and the wave activity flux, measured by the vertical component of the Eliassen-Palm flux (EPz) from both the troposphere and the stratosphere, are significantly related with each other and in lead-lag quadrature. While, in the low-frequency band of the downward propagation, the EPz anomalies of the opposite sign around NAM extremes drive the onset and decay of NAM events, we found that the EPz anomalies in the troposphere, are significantly larger after stratospheric vortex anomalies than at any time before. This marked difference in the troposphere is related to planetary waves with zonal wavenumbers 1-3, showing that there is a tropospheric planetary wave response to the earlier state of the stratosphere at low frequencies. We also find that this effect is due to anomalies in the EPz issued from the northern midlatitudes and polar regions.

  • 305. Nilsson, C.
    et al.
    Goyette, S.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Relating forest damage data to the wind field from high-resolution RCM simulations: Case study of Anatol striking Sweden in December 19992007In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 57, no 1-2, p. 161-176Article in journal (Refereed)
    Abstract [en]

    Forestry is of major economical importance in Europe, and recent devastating windstorms have pinpointed the vulnerability of this economic sector to windstorms. Forest damage is an important economic issue at a country level and may become even of larger concern under future conditions following global warming. An underlying question is to what extent the storm damage is due to changes in the wind climate compared to the effect of changes in forest management practices? In this paper, the first part of this rather complex problem is tackled. By using the Canadian Regional Climate Model, CRCM, including a physically based gust parameterisation scheme, NCEPNCAR reanalysis wind fields for the windstorm Anatol, on December 3-4, 1999, were downscaled, into a nested set-up, to 2 km resolution. The aim is to relate the simulated storm wind field to the observed distribution of storm damaged forests in Scania in southern Sweden, as a first methodological step towards analysing the effect of future windstorms in Swedish forests at the highest spatial resolution one can afford nowadays. Our results show that the CRCM produced realistic wind field simulations, compared to station observations, of the windstorm event in 1999. The simulated winds were underestimated at the coasts, but in congruence with inland observations. Most of the damaged forest stands were located on south-westerly (SW) slopes, which indicated a south-westerly wind during the wind throw process. This SW wind direction was evident in the early phase of the simulated storm, but then changed into a westerly flow, at an earlier stage than the true observations specified. Further, most damage occurred in the areas of simulated maximum wind speed greater than 30 m s. To conclude, the CRCM has proven to be a useful tool to realistically simulate a forest damaging storm event. Hence, the model could be used for further study cases, preferably driven by a GCM, in order to reveal a greater understanding about recent storms, which in turn helps us evaluate future climate change driven storm conditions. (c) 2006 Elsevier B.V All rights reserved.

  • 306. Nilsson, Cecilia
    et al.
    Dokter, Adriaan M.
    Verlinden, Liesbeth
    Shamoun-Baranes, Judy
    Schmid, Baptiste
    Desmet, Peter
    Bauer, Silke
    Chapman, Jason
    Alves, Jose A.
    Stepanian, Phillip M.
    Sapir, Nir
    Wainwright, Charlotte
    Boos, Mathieu
    Gorska, Anna
    Menz, Myles H. M.
    Rodrigues, Pedro
    Leijnse, Hidde
    Zehtindjiev, Pavel
    Brabant, Robin
    Haase, Günther
    SMHI, Research Department, Atmospheric remote sensing.
    Weisshaupt, Nadja
    Ciach, Michal
    Liechti, Felix
    Revealing patterns of nocturnal migration using the European weather radar network2019In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, no 5, p. 876-886Article in journal (Refereed)
  • 307. Ning, T.
    et al.
    Elgered, G.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Johansson, J. M.
    Evaluation of the atmospheric water vapor content in a regional climate model using ground-based GPS measurements2013In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 118, no 2, p. 329-339Article in journal (Refereed)
    Abstract [en]

    Ground-based GPS measurements can provide independent data for the assessment of climate models. We use the atmospheric integrated water vapor (IWV) obtained from GPS measurements at 99 European sites to evaluate the regional Rossby Centre Atmospheric climate model (RCA) driven at the boundaries by the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data (ERA Interim). The GPS data were compared to the RCA simulation and the ERA Interim data. The comparison was first made using the monthly mean values. Averaged over the domain and the 14 years covered by the GPS data, IWV differences of about 0.47 kg/m(2) and 0.39 kg/m(2) are obtained for RCA-GPS and ECMWF-GPS, respectively. The RCA-GPS standard deviation is 0.98 kg/m(2) whereas it is 0.35 kg/m(2) for the ECMWF-GPS comparison. The IWV differences for RCA are positively correlated to the differences for ECMWF. However, this is not the case for two sites in Italy where a wet bias is seen for ECMWF, while a dry bias is seen for RCA, the latter being consistent with a cold temperature bias found for RCA in that region by other authors. Comparisons of the estimated diurnal cycle and the spatial structure function of the IWV were made between the GPS data and the RCA simulation. The RCA captures the geographical variation of the diurnal peak in the summer. Averaged over all sites, a peak at 17 local solar time is obtained from the GPS data while it appears later, at 18, in the RCA simulation. The spatial variation of the IWV obtained for an RCA run with a resolution of 11 km gives a better agreement with the GPS results than does the spatial variation from a 50 km resolution run. Citation: Ning, T., G. Elgered, U. Willen, and J. M. Johansson (2013), Evaluation of the atmospheric water vapor content in a regional climate model using ground-based GPS measurements, J. Geophys. Res. Atmos., 118, 329-339, doi: 10.1029/2012JD018053.

  • 308. Ning, T.
    et al.
    Haas, R.
    Elgered, G.
    Willen, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Multi-technique comparisons of 10 years of wet delay estimates on the west coast of Sweden2012In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 86, no 7, p. 565-575Article, review/survey (Refereed)
    Abstract [en]

    We present comparisons of 10-year-long time series of the atmospheric zenith wet delay (ZWD), estimated using the global positioning system (GPS), geodetic very long baseline interferometry (VLBI), a water vapour radiometer (WVR), radiosonde (RS) observations, and the reanalysis product of the European Centre for Medium-Range Weather Forecasts (ECMWF). To compare the data sets with each other, a Gaussian filter is applied. The results from 10 GPS-RS comparisons using sites in Sweden and Finland show that the full width at half maximum at which the standard deviation (SD) is a minimum increases with the distance between each pair. Comparisons between three co-located techniques (GPS, VLBI, and WVR) result in mean values of the ZWD differences at a level of a few millimetres and SD of less than 7 mm. The best agreement is seen in the GPS-VLBI comparison with a mean difference of -3.4 mm and an SD of 5.1 mm over the 10-year period. With respect to the ZWD derived from other techniques, a positive bias of up to similar to 7 mm is obtained for the ECMWF reanalysis product. Performing the comparisons on a monthly basis, we find that the SD including RS or ECMWF varies with the season, between 3 and 15 mm. The monthly SD between GPS and WVR does not have a seasonal signature and varies from 3 to 7 mm.

  • 309.
    Nyberg, Anders
    SMHI.
    On transport of sulphur over the North Atlantic1976Report (Other academic)
    Abstract [en]

    The sulphur content in the precipitation collected 1 on ocean weather ships in the North Atlantic has been analysed . From these data and from results of trajectory computations it is concluded that considerable amounts of anthropogenic sulphur are transported from North America towards Europe. The dry deposition of sulphur over the Atlantic , except close to the emitting sources, must be very small. The amount of sulphur in the precipitation from air coming from the high pressure area near the Azores is very small and thus one can say that the normal value of natural sulphur in precipitation cannot be much larger than 0.1 mg/1.

  • 310. Näslund, J-O
    et al.
    Wohlfarth, B
    Alexandersson, H
    Helmens, K
    Hättestrand, M
    Jansson, P
    Kleman, J
    Lundqvist, J
    Brandefelt, J
    Houmark-Nielsen, M
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Knudsen, K.L
    Krog Larsen, N
    Ukkonen, P
    Mangerud, J
    Fennoscandian paleo-environment and ice sheet dynamics during Marine Isotope Stage (MIS) 32007Report (Other academic)
  • 311. Ogawa, Fumiaki
    et al.
    Keenlyside, Noel
    Gao, Yongqi
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Yang, Shuting
    Suo, Lingling
    Wang, Tao
    Gastineau, Guillaume
    Nakamura, Tetsu
    Cheung, Ho Nam
    Omrani, Nour-Eddine
    Ukita, Jinro
    Semenov, Vladimir
    Evaluating Impacts of Recent Arctic Sea Ice Loss on the Northern Hemisphere Winter Climate Change2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 7, p. 3255-3263Article in journal (Refereed)
  • 312.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Berg, Peter
    SMHI, Research Department, Hydrology.
    Eronn, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Simonsson, Lennart
    SMHI, Research Department, Hydrology.
    Södling, Johan
    SMHI, Professional Services.
    Wern, Lennart
    SMHI, Core Services.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Extremregn i nuvarande och framtida klimat Analyser av observationer och framtidsscenarier2018Report (Other academic)
    Abstract [sv]

    Studien har främst omfattat analyser av extrem korttidsnederbörd i observationer från SMHIs nät av automatiska meteorologiska stationer. Även analyser av korttidsnederbörd från kommunala mätare, manuella meteorologiska stationer, väderradar och klimatmodeller har genomförts. De huvudsakliga slutsatserna från detta uppdrag kan sammanfattas enligt följande.

    • En regionalisering av extrem korttidsnederbörd (skyfall) i Sverige gav fyra regioner: sydvästra (SV), sydöstra (SÖ), mellersta (M) och norra (N) Sverige. Ytterligare indelning kan göras men i denna studie prioriterades att ha regioner av denna storleksordning för att få ett ordentligt underlag för regional statistik. Regionaliseringen gäller enbart korttidsnederbörd, upp till maximalt 12 tim varaktighet.
    • Den regionala statistiken uppvisar tämligen distinkta geografiska skillnader, med högst värden i region SV och lägst i region N. Det är inte förvånande att vårt avlånga land uppvisar regionala skillnader då varmare och fuktigare luftmassor förekommer mer i söder än i norr, och därmed ökar förutsättningarna för intensiv nederbörd. Den regionala statistiken överensstämmer överlag väl med motsvarande statistik i våra grannländer.
    • Under perioden 1996-2017 finns inga tydliga tidsmässiga tendenser vad gäller skyfallens storlek och frekvens i de olika regionerna, utan dessa ligger överlag på en konstant nivå. Inte heller extrem dygnsnederbörd sedan 1900 uppvisar några tydliga tendenser på regional nivå. På nationell nivå indikeras en svag ökning av dels landets högsta årliga nederbörd sedan 1881, dels förekomsten av stora, utbredda 2-dygnsregn sedan 1961.
    • Skyfallsstatistik baserad på nederbördsobservationer från väderradar som justerats mot interpolerade stationsdata (HIPRAD) överensstämmer väl med stationsbaserad statistik för korta varaktigheter (upp till 2 tim) i södra Sverige. För längre varaktigheter och i mellersta och norra Sverige överskattar HIPRAD regnvolymerna.
    • Analyser av de senaste klimatmodellerna (Euro-CORDEX) indikerar en underskattning av extrema regnvolymer för korta varaktigheter (1 tim) men överlag en realistisk beskrivning av observerad skyfallsstatistik. Den framtida ökningen av volymerna beräknas ligga mellan 10% och 40% beroende på tidshorisont och koncentration av växthusgaser, vilket överlag ligger nära tidigare bedömningar.

    Både för bedömningen av regionala skillnader och historiska klimateffekter är det av största vikt att bibehålla, eller ännu hellre utöka, observationerna av korttidsnederbörd i Sverige. Nederbördsmätning via alternativa tekniker bör kunna användas i allt högre utsträckning framöver för förbättrad kunskap och statistik. Väderradar är redan etablerat och den digitala utvecklingen öppnar även möjligheter till insamling av nederbördsdata och relaterad information via mobilmaster, uppkopplade privata väderstationer, sociala medier, etc. Denna utveckling måste bevakas, utvärderas och i största möjliga utsträckning utnyttjas.

  • 313.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Professional Services.
    Rosberg, Jörgen
    SMHI, Research Department, Hydrology.
    Hellström, Sara-Sofia
    SMHI, Research Department, Hydrology.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Berndtsson, Ronny
    Lund University, Department of Water Resources Engineering, .
    Simulation of Runoff in the Baltic Sea Drainage Basin During the Past Millennium2007Conference paper (Other academic)
  • 314.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Josefsson, Weine
    SMHI, Core Services.
    Skyfallsuppdraget ett regeringsuppdrag till SMHI2015Report (Other academic)
    Abstract [en]

    Arbetet har sammanfattats i en rapport, som kan betraktas som en lägesrapport, inkluderar en omvärldsanalys; vad som gjorts i Sverige och i andra länder, delvis inhämtat vid en expertworkshop. Rapporten innehåller också en bearbetning av SMHIs nederbördsobservationer avseende korttidsnederbörd (skyfall) och en diskussion kring olika statistiska metoder att analysera dessa observationer. Dessutom har SMHIs nuvarande system för att prognosera skyfall uppgraderats och i rapporten diskuteras även vilka möjligheter som finns att ytterligare förbättra prognoserna i framtiden. Den pågående klimatförändringen påverkar vädret och därmed skyfallen. Rapporten tar upp de senaste rönen inom forskningen och även de negativa effekter som skyfall ger på samhället. Vilka behov finns i samhället och vad kan vi göra för att minimera de negativa effekterna var något som diskuterades vid en användarworkshop.

  • 315. Olusegun, Christiana Funmilola
    et al.
    Oguntunde, Philip G.
    Gbobaniyi, Bode
    SMHI, Research Department, Climate research - Rossby Centre. SMHI, Professional Services.
    Simulating the Impacts of Tree, C3, and C4 Plant Functional Types on the Future Climate of West Africa2018In: Climate, ISSN 2053-7565, E-ISSN 2225-1154, Vol. 6, no 2, article id 35Article in journal (Refereed)
  • 316.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    A sensitivity analysis of steady, free floating ice1980Report (Other academic)
    Abstract [en]

    The equation for steady, free floating ice is derived and analysed for a shallow sea. The analysis treats how accurate the free ice drift can be computed when variations in the ingoing parameters are introduced. Besides errors due to  unperfect winds, areas with large currents cause bad accuracy. If further more the bottom depth is neglected in these areas the accuracy become worse. Variable ice roughness and variable friction velocity introduce errors which are less important but still noticable in the computed ice drift.

  • 317. Omstedt, Anders
    et al.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    Claremar, Bjorn
    Rutgersson, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Modelling the contributions to marine acidification from deposited SOx, NOx, and NHx in the Baltic Sea: Past and present situations2015In: Continental Shelf Research, ISSN 0278-4343, E-ISSN 1873-6955, Vol. 111, p. 234-249Article in journal (Refereed)
    Abstract [en]

    We have examined the effects of historical atmospheric depositions of sulphate, nitrate, and ammonium from land and shipping on the acid-base balance in the Baltic Sea. The modelling considers the 1750-2014 period, when land and ship emissions changed greatly, with increasing carbon dioxide concentrations, SOx, NOx, and NHx emissions, and nutrient loads. The present results indicate that Baltic Sea acidification due to the atmospheric deposition of acids peaked around 1980, with a pH cumulative decrease of approximately 10(-2) in surface waters. This is one order of magnitude less than the cumulative acidification due to increased atmospheric CO2. The acidification contribution of shipping is one order of magnitude less than that of land emissions. However, the pH trend due to atmospheric acids has started to reverse due to reduced land emissions, though the effect of shipping is ongoing. The effect of strong atmospheric acids on Baltic Sea water depends on the region and period studied. The largest total alkalinity sink per surface area is in the south-western Baltic Sea where shipping is intense. Considering the entire Baltic Sea over the 2001-2010 period, the pH changes are approximately -3 x 10(-3) to -11 x 10(-3) and -4 x 10(-4) to -16 x 10(-4) pH units attributable to all emissions and ship emissions only, respectively. The corresponding changes in total alkalinity are approximately -10 to -30 mu mol kg(-1) and -1 to -4 mu mol kg(-1) attributable to all emissions and ship emissions only, respectively. (C) 2015 Elsevier Ltd. All rights reserved.

  • 318.
    Omstedt, Anders
    et al.
    SMHI, Research Department, Oceanography.
    Gustafsson, B
    Rodhe, J
    Walin, G
    Use of Baltic Sea modelling to investigate the water cycle and the heat balance in GCM and regional climate models2000In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 15, no 2, p. 95-108Article in journal (Refereed)
    Abstract [en]

    Results from the first simulations with the Rossby Centre regional climate atmosphere (RCA) model were used to force 2 versions of process-oriented models of the Baltic Sea-one time-dependent, the other considering the mean state. The purpose was primarily to obtain a first scenario of the future state of the Baltic Sea. In addition, we looked at this exercise as a method to evaluate the consistency of the water cycle and the heat balance produced by atmospheric climate models. The RCA model is a high-resolution atmospheric regional model which is forced with lateral conditions from a global model. A large-scale Baltic drainage basin hydrological model, forced by the RCA model, was used to simulate river runoff. Using RCA model data from the control run we found that that the temperature and ice conditions in the Baltic Sea were reasonably realistic while the salinity field was poorly reproduced. We conclude that the modelling of the water cycle needs considerable improvement. We also conclude that the time for the Baltic Sea to respond to the water cycle is much longer than the integration period so far used with the RCA model. Forcing the ocean models with RCA model data from a future scenario with an enhanced greenhouse effect gives an increased sea-surface temperature and a much reduced extent of ice in the Baltic Sea due to climate warming. Also the salinity is reduced, which implies possible serious effects on the future marine life in the Baltic Sea. The results demonstrate that accurate atmospheric modelling of not only the heat balance but also the water cycle is crucial for Baltic Sea climate simulations.

  • 319.
    Omstedt, Anders
    et al.
    SMHI, Research Department, Oceanography.
    Rutgersson, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Closing the water and heat cycles of the Baltic Sea2000In: Meteorologische Zeitschrift, ISSN 0941-2948, E-ISSN 1610-1227, Vol. 9, no 1, p. 59-66Article in journal (Refereed)
    Abstract [en]

    The objective of the present paper is to analyze the water and heat cycles of the Baltic Sea. The closure equations fur the water and heat cycles are formulated and the appropriate fluxes are calculated using the ocean model PROBE-Baltic forced by meteorological fields, river runoff and sea level data from the Kattegat. The time period considered is from November 1980 to November 1995. In the closing of the water cycle it is clear that river runoff, net precipitation (precipitation minus evaporation), in- and outflows through the Baltic Sea entrance area are the dominating flows. From the ocean model it is illustrated that the long-term water balance is consistent with the salinity in the Baltic Sea and that the net precipitation is positive during the studied period. For the closing of the heat cycle, the net heat loss to the atmosphere from the open water surface, as an annual moan, is in close balance with the solar radiation. The dominating fluxes in the net heat loss to the atmosphere are the sensible heat flux, the latent heat Aux and the net long wave radiation. The heat flux from water to ice also needs to be included in the modeling efforts. Heat flows associated with precipitation in the form of rain and snow can, as annual means, be neglected as well as the heat fluxes associated with river runoff, solar radiation through the ice and ice advecting out through the Baltic Sea entrance area. The total annual mean heat loss from the water body is in close balance with the annual change of heat storage in the water and the net heat exchange through the Baltic Sea entrance area is small. This illustrates that the Baltic Sea thermodynamically responds as a closed ocean basin.

  • 320.
    Omstedt, Anders
    et al.
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Some results from a joint Swedish-Finnish sea ice experiment, March, 19771978Report (Other academic)
    Abstract [en]

    A joint Swedish-Finnish sea-ice experiment was performed during March 1977. Measurements in the atmosphere, ice and sea were made during six days onboard the Finnish Research vessel Aranda stationed in the ice field in the Bay of Bothnia. During two days measurements were also carried out from thetwo Swedish icebreakers Atle and Tor. This report presents the data and some results from the Swedish group.

  • 321. Orsolini, Yvan J.
    et al.
    Karpechko, Alexey Yu.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Variability of the Northern Hemisphere polar stratospheric cloud potential: The role of North Pacific disturbances2009In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 135, no 641, p. 1020-1029Article in journal (Refereed)
    Abstract [en]

    The potential of the Arctic stratosphere to sustain the formation of Polar Stratospheric Clouds (PSCs) is a key factor in determining the amount of ozone destroyed each winter, and is often measured as a 'PSC volume'. The latter quantity has been shown to closely follow a near-linear compact relationship with winter-averaged column ozone loss, and displays a high variability from monthly to decadal time-scales. We examine the connection between meteorological conditions in the troposphere and the variability of lower polar stratospheric temperatures over the last four decades, and specifically, conditions leading to a high PSC volume. In addition to the well-established connection between the North Atlantic Oscillation (NAO) and the polar vortex, we demonstrate the large influence of precursory disturbances over the North Pacific and the Far East, the region of maximum climatological upward wave activity flux. Namely, very high monthly PSC volume (in the top 12%) predominantly follows the development of positive tropospheric height anomalies over the Far East, which lead to a weakening of the background planetary wave trough, and lessened upward wave activity flux into the stratosphere. Precursory anomalies over the Far East are reminiscent of East Asian monsoon amplification episodes. Copyright (C) 2009 Royal Meteorological Society

  • 322. Osima, Sarah
    et al.
    Indasi, Victor S.
    Zaroug, Modathir
    Endris, Hussen Seid
    Gudoshava, Masilin
    Misiani, Herbert O.
    Nimusiima, Alex
    Anyah, Richard O.
    Otieno, George
    Ogwang, Bob A.
    Jain, Suman
    Kondowe, Alfred L.
    Mwangi, Emmah
    Lennard, Chris
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Dosio, Alessandro
    Projected climate over the Greater Horn of Africa under 1.5 degrees C and 2 degrees C global warming2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065004Article in journal (Refereed)
  • 323. Ott, Irena
    et al.
    Duethmann, Doris
    Liebert, Joachim
    Berg, Peter
    SMHI, Research Department, Climate research - Rossby Centre.
    Feldmann, Hendrik
    Ihringer, Juergen
    Kunstmann, Harald
    Merz, Bruno
    Schaedler, Gerd
    Wagner, Sven
    High-Resolution Climate Change Impact Analysis on Medium-Sized River Catchments in Germany: An Ensemble Assessment2013In: Journal of Hydrometeorology, ISSN 1525-755X, E-ISSN 1525-7541, Vol. 14, no 4, p. 1175-1193Article in journal (Refereed)
    Abstract [en]

    The impact of climate change on three small- to medium-sized river catchments (Ammer, Mulde, and Ruhr) in Germany is investigated for the near future (2021-50) following the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario. A 10-member ensemble of hydrological model (HM) simulations, based on two high-resolution regional climate models (RCMs) driven by two global climate models (GCMs), with three realizations of ECHAM5 (E5) and one realization of the Canadian Centre for Climate Modelling and Analysis version 3 (CCCma3; C3) is established. All GCM simulations are downscaled by the RCM Community Land Model (CLM), and one realization of E5 is downscaled also with the RCM Weather Research and Forecasting Model (WRF). This concerted 7-km, high-resolution RCM ensemble provides a sound basis for runoff simulations of small catchments and is currently unique for Germany. The hydrology for each catchment is simulated in an overlapping scheme, with two of the three HMs used in the project. The resulting ensemble hence contains for each chain link (GCM-realization-RCM-HM) at least two members and allows the investigation of qualitative and limited quantitative indications of the existence and uncertainty range of the change signal. The ensemble spread in the climate change signal is large and varies with catchment and season, and the results show that most of the uncertainty of the change signal arises from the natural variability in winter and from the RCMs in summer.

  • 324. Palmer, T N
    et al.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Quantifying the risk of extreme seasonal precipitation events in a changing climate2002In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 415, no 6871, p. 512-514Article in journal (Refereed)
    Abstract [en]

    Increasing concentrations of atmospheric carbon dioxide will almost certainly lead to changes in global mean climate(1). But because-by definition-extreme events are rare, it is significantly more difficult to quantify the risk of extremes. Ensemble-based probabilistic predictions(2), as used in short- and medium-term forecasts of weather and climate, are more useful than deterministic forecasts using a 'best guess' scenario to address this sort of problem(3,4). Here we present a probabilistic analysis of 19 global climate model simulations with a generic binary decision model. We estimate that the probability of total boreal winter precipitation exceeding two standard deviations above normal will increase by a factor of five over parts of the UK over the next 100 years. We find similar increases in probability for the Asian monsoon region in boreal summer, with implications for flooding in Bangladesh. Further practical applications of our techniques would be helped by the use of larger ensembles (for a more complete sampling of model uncertainty) and a wider range of scenarios at a resolution adequate to analyse average-size river basins.

  • 325. Paprotny, D.
    et al.
    Morales-Napoles, O.
    Vousdoukas, M. I.
    Jonkman, S. N.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Accuracy of pan-European coastal flood mapping2019In: Journal of Flood Risk Management, ISSN 1753-318X, E-ISSN 1753-318X, Vol. 12, no 2, article id UNSP e12459Article in journal (Refereed)
  • 326. Paquin, Jean-Philippe
    et al.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Sushama, Laxmi
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Causes and consequences of mid-21st-century rapid ice loss events simulated by the Rossby centre regional atmosphere-ocean model2013In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 65, article id 19110Article in journal (Refereed)
    Abstract [en]

    Recent observations and modelling studies suggest that the Arctic climate is undergoing important transition. One manifestation of this change is seen in the rapid sea-ice cover decrease as experienced in 2007 and 2012. Although most numerical climate models cannot adequately reproduce the recent changes, some models produce similar Rapid Ice Loss Events (RILEs) during the mid-21st-century. This study presents an analysis of four specific RILEs clustered around 2040 in three transient climate projections performed with the coupled Rossby Centre regional Atmosphere-Ocean model (RCAO). The analysis shows that long-term thinning causes increased vulnerability of the Arctic Ocean sea-ice cover. In the Atlantic sector, pre-conditioning (thinning of sea ice) combined with anomalous atmospheric and oceanic heat transport causes large ice loss, while in the Pacific sector of the Arctic Ocean sea-ice albedo feedback appears important, particularly along the retreating sea-ice margin. Although maximum sea-ice loss occurs in the autumn, response in surface air temperature occurs in early winter, caused by strong increase in ocean-atmosphere surface energy fluxes, mainly the turbulent fluxes. Synchronicity of the events around 2040 in the projections is caused by a strong large-scale atmospheric circulation anomaly at the Atlantic lateral boundary of the regional model. The limited impact on land is caused by vertical propagation of the surface heat anomaly rather than horizontal, caused by the absence of low-level temperature inversion over the ocean.

  • 327. Paquin-Ricard, Danahe
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Vaillancourt, Paul A.
    Using ARM Observations to Evaluate Cloud and Clear-Sky Radiation Processes as Simulated by the Canadian Regional Climate Model GEM2010In: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 138, no 3, p. 818-838Article in journal (Refereed)
    Abstract [en]

    The total downwelling shortwave (SWID) and longwave (LWD) radiation and its components are assessed for the limited-area version of the Global Environmental Multiscale Model (GEM-LAM) against Atmospheric Radiation Measurements (ARM) at two sites: the southern Great Plains (SGP) and the North Slope of Alaska (NSA) for the 1998-2005 period. The model and observed SWD and LWD are evaluated as a function of the cloud fraction (CF), that is, for overcast and clear-sky conditions separately, to isolate and analyze different interactions between radiation and 1) atmospheric aerosols and water vapor and 2) cloud liquid water. Through analysis of the mean diurnal cycle and normalized frequency distributions of surface radiation fluxes, the primary radiation error in GEM-LAM is seen to be an excess in SWD in the middle of the day. The SWD bias results from a combination of underestimated CF and clouds, when present, possessing a too-high solar transmissivity, which is particularly the case for optically thin clouds. Concurrent with the SWD bias, a near-surface warm bias develops in GEM-LAM, particularly at the SGP site in the summer. The ultimate cause of this warm bias is difficult to uniquely determine because of the range of complex interactions between the surface, atmospheric, and radiation processes that are involved. Possible feedback loops influencing this warm bias are discussed. The near-surface warm bias is the primary cause of an excess clear-sky LWD. This excess is partially balanced with respect to the all-sky LWD by an underestimated CF, which causes a negative bias in simulated all-sky emissivity. It is shown that there is a strong interaction between all the components influencing the simulated surface radiation fluxes with frequent error compensation, emphasizing the need to evaluate the individual radiation components at high time frequency.

  • 328.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    En modell för beräkning av luftföroreningars spridning och deposition på mesoskala1980Report (Other academic)
    Abstract [sv]

    Mängden föroreningar, som förs till atmosfären, har under de senaste trettio åren kraftigt ökats. Deposition av dessa till marken leder till en rad biologiska effekter. Risker för skador på olika ekosystem genom deposition av tex tungmetaller och syra har därför alltmer börjat diskuteras som viktiga lokaliseringskriterier för fossileldade kraftverk och vissa större industrier. Depositionen av bly i omedelbar närhet av livligt trafikerade motorleder är ett annat exempel där negativa miljöeffekter befaras.

    Uppställandet av effektrelaterade utsläppskriterier medför ett behov av redskap för att kunna göra kvantitativa uppskattningar av förväntade depositioner i omgivningen av en källa. För kraftverk kan behovet av information om depositionsfördelningen, som underlag för lokaliseringsbeslut, röra ett område med flera hundra kilometers utsträckning.

    Vid studier av den lokala spridningen runt en punktkälla har under lång tid den gaussiska plymmodellen varit allmänt använd. Den utgör ett enkelt och i många fall mycket bra hjälpmedel, men har avsevärda begränsningar i de fall då depositionsprocesser och kemiska omvandlingar måste inkluderas i beräkningarna. I modeller baserade på diffusionsekvationen, där vissa antaganden om den turbulenta diffusiviteten görs (sk K-teori), finns möjlighet att på ett väsentligt mer realistiskt sätt inkludera processer som rör deposition och kemiska omvandlingar. Nackdelen är dock att den matematiska behandlingen blir mer komplicerad.

    Numeriska lösningar av diffusionsekvationen har använts av tex Bo in & Persson (1975) och Omstedt & Rodhe (1977). I båda fallen gällde tillämpningarna föroreningsspridning på storregional skala. Maul (1977) har presenterat en analytisk lösning, som tillämpats på föroreningsspridning på mesoskala. Svårigheterna vid tillämpningen av K-teorin är framförallt att bestämma riktiga värden på de ingångsparametrar som fordras. För analytiska lösningar finns dessutom matematiska hinder för godtyckliga vind- och diffusivitetsprofiler. Detta har resulterat i att beräkningar med K-modeller hittills huvudsakligen utförts för några enkla medelprofiler.

    Avsikten med föreliggande projekt har varit att utveckla en för praktiskt brukanvändbar spridningsmodell för studier av torr- och våtdepositionen av föroreningar på lokal- och mesoskala, där godtyckliga vind- och diffusivitetsprofiler kan användas. Dessa genereras med hjälp av en gränsskiktsmodell för olika vädersituationer.

  • 329.
    Persson, Gunn
    SMHI, Professional Services.
    How much does it rain?2004In: Water research what´s next? / [ed] B. Johansson, Formas, Stockholm, Sweden,, 2004, p. 15-18Conference paper (Other academic)
  • 330.
    Persson, Gunn
    SMHI, Professional Services.
    Klimatförändringar i framtiden2006In: Poppel- sammanfattningar från ett seminarium vid Institutionen för Lövträdsodling, SLU , 2006, p. 66-67Conference paper (Other academic)
  • 331.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Nylén, Linda
    SMHI, Professional Services.
    Berggreen-Clausen, Steve
    SMHI, Professional Services.
    Berg, Peter
    SMHI, Research Department, Climate research - Rossby Centre.
    Rayner, David
    SMHI.
    Sjökvist, Elin
    SMHI, Professional Services.
    Från utsläppsscenarier till lokal nederbörd och översvämningsrisker2016Report (Other academic)
    Abstract [en]

    In this report methods and results are presented from downscaling of about 40 climate scenarios to local time series for two drainage areas; River Torneå in northern Sweden and River Ätran in southern Sweden. Hydrological and hydraulic modelling has been made and flood maps have been produced for the cities Haparanda and Falkenberg. A study of future extreme precipitation is also presented. The work was performed within the project “Future rainfall and flooding in Sweden” financed by the Swedish Civil Contingencies Agency (MSB).

  • 332.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Berg, Peter
    SMHI, Research Department, Climate research - Rossby Centre.
    Vägledning för användande av klimatscenarier2015Report (Other academic)
    Abstract [sv]

    SMHI fick i sitt regleringsbrev för år 2014 uppdraget att, i samråd med berörda myndigheter och andra aktörer, ta fram en vägledning för användandet av klimatscenarier. Enligt önskemål framtogs vägledningen som en webb-produkt på smhi.se, i anslutning till klimatscenarier. Materialet finns även samlat i denna rapport, såsom det lanserades hösten 2014. Eftersom materialet är uppbyggt för webb-presentation, där läsaren ska kunna gå in i kapitel utan att ha läst de tidigare, förekommer en del upprepningar. Klimatscenarier är beskrivningar av hur klimatet kan utvecklas i framtiden. Vägledningen ger stöd för att tolka och använda klimatscenarier, med dess möjligheter och begränsningar. Klimateffektstudier beskrivs översiktligt och med fokus på hydrologiska effektstudier. Några enkla steg för att komma igång med klimatanpassning presenteras också. I ordlistan förklaras de begrepp som används.

  • 333.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Wikberger, Christina
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Klimatanpassa nordiska städer med grön infrastruktur2018Report (Other academic)
    Abstract [sv]

    Förtätning av städer och pågående klimatförändring ökar behovet av anpassningsåtgärder. Grön infrastruktur och naturbaserade lösningar kan bidra till att skapa mer hälsosamma och långsiktigt hållbara städer. För att öka användningen av grön infrastruktur som en del i klimatanpassningen behöver vi förstå vilka kunskapsluckor och andra hinder som ligger i vägen för att grön infrastruktur ska användas i klimatanpassningsarbetet.

    SMHI har under år 2018 tillsammans med Stockholms stad drivit det av forskningsrådet Formas finansierade projektet ”Grön infrastruktur och klimat i nordiska städer: idag och i framtiden”. Sammanställningen av rapporter och workshops i projektet visar att det finns mycket kunskap och tillgängliga exempel på hur urbana gröna lösningar kan se ut. Det saknas dock svar på de kvantitativa effekterna av olika åtgärder avseende till exempel temperatur, luftkvalitet, påverkan på hälsa och sociala aspekter.

    De åtgärder som i dag görs i nordiska städer baseras huvudsakligen på behovet av att lösa dagvattenfrågor. Det finns få exempel på städer som använder grön infrastruktur och naturbaserade lösningar som klimatanpassningsåtgärder när det gäller värme. Samtidigt är aktörerna medvetna om övriga positiva effekter som tillkommer såsom trivsel, svalka och biologisk mångfald.

    Eftersom grön infrastruktur och naturbaserade lösningar är ganska nya åtgärder i klimatanpassningsarbetet så saknas oftast erfarenheter av långtidseffekter. Skötsel kan vara ett problem, trots bra anvisningar. Aktörerna pekar också på behovet av att engagera de boende kontinuerligt. Det tycks handla om att skapa en djupare förståelse för varför anläggningar ser ut som de gör och hur de ska skötas.

    Vid workshops och webbinarium efterfrågades vilka kunskapsluckor deltagarna såg. Ekonomi och kunskap om effekter lyftes fram tydligt i svaren. Dessutom önskades metoder för anläggning och drift, goda exempel, planeringsverktyg och underlag om temperatur och vatten.

    Ekonomi och kunskapsbrist ansågs som hinder för genomförande, vilket framkom vid workshops och webbinarium. Andra hinder som nämndes var politiska beslut, lagstiftning, avsaknad av riktlinjer, förtätning och konkurrens om mark liksom planerings- och samordningssvårigheter. En tröghet i att ändra traditionellt planerande och utförande pekades också ut som hinder. Många efterfrågar kunskap allmänt. Vår förhoppning är att denna rapport kan bidra till att inspirera och informera om var material finns. 

  • 334. Pessacg, Natalia L.
    et al.
    Solman, Silvina A.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Sanchez, Enrique
    Marengo, Jose
    Li, Laurent
    Remedio, Armelle Reca C.
    da Rocha, Rosmeri P.
    Mourao, Caroline
    Jacob, Daniela
    The surface radiation budget over South America in a set of regional climate models from the CLARIS-LPB project2014In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 43, no 5-6, p. 1221-1239Article in journal (Refereed)
    Abstract [en]

    The performance of seven regional climate models in simulating the radiation and heat fluxes at the surface over South America (SA) is evaluated. Sources of uncertainty and errors are identified. All simulations have been performed in the context of the CLARIS-LPB Project for the period 1990-2008 and are compared with the GEWEX-SRB, CRU, and GLDAS2 dataset and NCEP-NOAA reanalysis. Results showed that most of the models overestimate the net surface short-wave radiation over tropical SA and La Plata Basin and underestimate it over oceanic regions. Errors in the short-wave radiation are mainly associated with uncertainties in the representation of surface albedo and cloud fraction. For the net surface long-wave radiation, model biases are diverse. However, the ensemble mean showed a good agreement with the GEWEX-SRB dataset due to the compensation of individual model biases. Errors in the net surface long-wave radiation can be explained, in a large proportion, by errors in cloud fraction. For some particular models, errors in temperature also contribute to errors in the net long-wave radiation. Analysis of the annual cycle of each component of the energy budget indicates that the RCMs reproduce generally well the main characteristics of the short- and long-wave radiations in terms of timing and amplitude. However, a large spread among models over tropical SA is apparent. The annual cycle of the sensible heat flux showed a strong overestimation in comparison with the reanalysis and GLDAS2 dataset. For the latent heat flux, strong differences between the reanalysis and GLDAS2 are calculated particularly over tropical SA.

  • 335. Peterson, T C
    et al.
    Easterling, D R
    Karl, T R
    Groisman, P
    Nicholls, N
    Plummer, N
    Torok, S
    Auer, I
    Boehm, R
    Gullett, D
    Vincent, L
    Heino, R
    Tuomenvirta, H
    Mestre, O
    Szentimrey, T
    Salinger, J
    Forland, E J
    Hanssen-Bauer, I
    Alexandersson, Hans
    SMHI.
    Jones, P
    Parker, D
    Homogeneity adjustments of in situ atmospheric climate data: A review1998In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 18, no 13, p. 1493-1517Article in journal (Refereed)
    Abstract [en]

    Long-term in situ observations are widely used in a variety of climate analyses. Unfortunately, most decade- to century-scale time series of atmospheric data have been adversely impacted by inhomogeneities caused by, for example, changes in instrumentation, station moves, changes in the local environment such as urbanization, or the introduction of different observing practices like a new formula for calculating mean daily temperature or different observation times. If these inhomogeneities are not accounted for properly, the results of climate analyses using these data on be erroneous. Over the last decade, many climatologists have put a great deal of effort into developing techniques to identify inhomogeneities and adjust climatic time series to compensate for the biases produced by the inhomogeneities. It is important for users of homogeneity-adjusted data to understand how the data were adjusted and what impacts these adjustments are likely to make on their analyses. And it is important for developers of homogeneity-adjusted data sets to compare readily the different techniques most commonly used today. Therefore, this paper reviews the methods and techniques developed for homogeneity adjustments and describes many different approaches and philosophies involved in adjusting in situ climate data. (C) 1998 Royal Meteorological Society.

  • 336. Pinto, Izidine
    et al.
    Lennard, Christopher
    Tadross, Mark
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Shongwe, Mxolisi E.
    Evaluation and projections of extreme precipitation over southern Africa from two CORDEX models2016In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 135, no 3-4, p. 655-668Article in journal (Refereed)
  • 337. Pisinaras, Vassilios
    et al.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Gemitzi, Alexandra
    Conceptualizing and assessing the effects of installation and operation of photovoltaic power plants on major hydrologic budget constituents2014In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 493, p. 239-250Article in journal (Refereed)
    Abstract [en]

    This study addresses the effects of land use change from agricultural to photovoltaic parks (PVPs) on the hydrology of an area. Although many environmental effects have been identified and analyzed, only minor attention has been given to the hydrologic effects of the installation and operation of PVPs. The effects of current PVP installation and operation practices on major hydrologic budget constituents (surface runoff, evapotranspiration and percolation) were identified, conceptualized, quantified and simulated using SWAT model. Vosvozis river basin located in north Greece was selected as a test site. Additionally, long-term effects were simulated using dynamically downscaled climate projections by a Regional Climate Model (RCM) driven by 5 different General Circulation Models (GCMs) for the period 2011-2100. Results indicate that surface runoff and percolation potential are significantly increased at the local scale and have to be considered during PVP siting, especially when sensitive and protected ecosystems are involved. (C) 2014 Elsevier B.V. All rights reserved.

  • 338. Porson, Aurore N.
    et al.
    Hagelin, Susanna
    SMHI, Research Department, Climate research - Rossby Centre.
    Boyd, Douglas F. A.
    Roberts, Nigel M.
    North, Rachel
    Webster, Stuart
    Lo, Jeff Chun-Fung
    Extreme rainfall sensitivity in convective-scale ensemble modelling over Singapore2019In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870XArticle in journal (Refereed)
  • 339. Prein, A. F.
    et al.
    Gobiet, A.
    Truhetz, H.
    Keuler, K.
    Goergen, K.
    Teichmann, C.
    Maule, C. Fox
    van Meijgaard, E.
    Deque, M.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Vautard, R.
    Colette, A.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jacob, D.
    Precipitation in the EURO-CORDEX 0.11 degrees and 0.44 degrees simulations: high resolution, high benefits?2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 1-2, p. 383-412Article in journal (Refereed)
    Abstract [en]

    In the framework of the EURO-CORDEX initiative an ensemble of European-wide high-resolution regional climate simulations on a 0.11 degrees (similar to 12.5 km) grid has been generated. This study investigates whether the fine-gridded regional climate models are found to add value to the simulated mean and extreme daily and sub-daily precipitation compared to their coarser-gridded 0.44 degrees (similar to 50 km) counterparts. Therefore, pairs of fine-and coarse-gridded simulations of eight reanalysis-driven models are compared to fine-gridded observations in the Alps, Germany, Sweden, Norway, France, the Carpathians, and Spain. A clear result is that the 0.11 degrees simulations are found to better reproduce mean and extreme precipitation for almost all regions and seasons, even on the scale of the coarser-gridded simulations (50 km). This is primarily caused by the improved representation of orography in the 0.11 degrees simulations and therefore largest improvements can be found in regions with substantial orographic features. Improvements in reproducing precipitation in the summer season appear also due to the fact that in the fine-gridded simulations the larger scales of convection are captured by the resolved-scale dynamics. The 0.11 degrees simulations reduce biases in large areas of the investigated regions, have an improved representation of spatial precipitation patterns, and precipitation distributions are improved for daily and in particular for 3 hourly precipitation sums in Switzerland. When the evaluation is conducted on the fine (12.5 km) grid, the added value of the 0.11 degrees models becomes even more obvious.

  • 340. Pryor, S. C.
    et al.
    Barthelmie, R. J.
    Clausen, N. E.
    Drews, M.
    MacKellar, N.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Analyses of possible changes in intense and extreme wind speeds over northern Europe under climate change scenarios2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 38, no 1-2, p. 189-208Article in journal (Refereed)
    Abstract [en]

    Dynamical downscaling of ECHAM5 using HIRHAM5 and RCA3 for a northern European domain focused on Scandinavia indicates sustained extreme wind speeds with long recurrence intervals (50 years) and intense winds are not likely to evolve out of the historical envelope of variability until the end of C21st. Even then, significant changes are indicated only in the SW of the domain and across the central Baltic Sea where there is some evidence for relatively small magnitude increases in the 50 year return period wind speed (of up to 15%). There are marked differences in results based on the two Regional Climate Models. Additionally, internal (inherent) variability and initial conditions exert a strong impact on projected wind climates throughout the twenty-first century. Simulations of wind gusts by one of the RCMs (RCA3) indicate some evidence for increased magnitudes (of up to +10%) in the southwest of the domain and across the central Baltic Sea by the end of the current century. As in prior downscaling of ECHAM4, dynamical downscaling of ECHAM5 indicates a tendency towards increased energy density and thus wind power generation potential over the course of the C21st. However, caution should be used in interpreting this inference given the high degree of wind climate projection spread that derives from the specific AOGCM and RCM used in the downscaling.

  • 341. Pryor, S C
    et al.
    Barthelmie, R J
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Potential climate change impact on wind energy resources in northern Europe: analyses using a regional climate model2005In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 25, no 7-8, p. 815-835Article in journal (Refereed)
    Abstract [en]

    There is considerable interest in the potential impact of climate change on the feasibility and predictability of renewable energy sources including wind energy. This paper presents dynamically downscaled near-surface wind fields and examines the impact of climate change on near-surface flow and hence wind energy density across northern Europe. It is shown that: Simulated wind fields from the Rossby Centre coupled Regional Climate Model (RCM) (RCAO) with boundary conditions derived from ECHAM4/OPYC3 AOGCM and the HadAM3H atmosphere-only GCM exhibit reasonable and realistic features as documented in reanalysis data products during the control period (1961-1990). The near-surface wind speeds calculated for a climate change projection period of 2071-2100 are higher than during the control run for two IPCC emission scenarios (A2, B2) for simulations conducted using boundary conditions from ECHAM4/OPYC3. The RCAO simulations conducted using boundary conditions from ECHAM4/OPYC3 indicate evidence for a small increase in the annual wind energy resource over northern Europe between the control run and climate change projection period and for more substantial increases in energy density during the winter season. However, the differences between the RCAO simulations for the climate projection period and the control run are of similar magnitude to differences between the RCAO fields in the control period and the NCEP/NCAR reanalysis data. Additionally, the simulations show a high degree of sensitivity to the boundary conditions, and simulations conducted using boundary conditions from HadAM3H exhibit evidence of slight declines or no change in wind speed and energy density between 1961-1990 and 2071-2100. Hence, the uncertainty of the projected wind changes is relatively high.

  • 342. Pryor, S. C.
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Influence of spatial resolution on regional climate model derived wind climates2012In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 117, article id D03117Article in journal (Refereed)
    Abstract [en]

    Wind speeds for a nominal height of 10 m and from the lowest model level (similar to 70 m above ground level) from the Rossby Center regional climate model (RCM) (RCA3) run at four resolutions between approximately 50 x 50 km and 6 x 6 km are analyzed to assess the effect of model resolution on wind climates. The influence of model resolution in this topographically simple subdomain of northern Europe is more profound in the wind extremes than in the central tendency. The domain-averaged mean wind speed at 10 m increases by 5% as the resolution increases from 50 to 6.25 km, while the 50 year return period wind speed and wind gust at this height increase by over 10% and 24%, respectively. Larger changes are observed in these wind speed metrics at the lowest model level as model resolution increases (similar to+10% in the mean and similar to+20% in the 50 year return period wind speed). These differences are of similar magnitude to the climate change signal in extreme wind events derived in prior research and may have implications for climate change risk and vulnerability analyses. Output from the lowest model level indicates some evidence for increased variability at synoptic and meso-alpha time scales with increased model resolution, but the effect is nonlinear. Furthermore, analysis of power spectra of grid cell average and tile fraction wind speeds at 10 m does not support the assertion that increased model resolution increases model skill at synoptic and meso-a time scales relative to in situ observations.

  • 343. Pryor, S.C.
    et al.
    Barthelmie, R.J.
    Schoof, J.T.
    Clausen, N.E.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Drews, M.
    Intense and extreme wind speeds over the Nordic countries2010Conference paper (Other academic)
  • 344. Pryor, S.C.
    et al.
    Barthelmie1, R.J.
    Claussen, N.E.
    Nielsen, N.M.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Drews, M.
    Climate change impacts on extreme wind speeds2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M, 2009, p. 271-272Conference paper (Other academic)
  • 345. Pucik, Tomas
    et al.
    Groenemeijer, Pieter
    Raedler, Anja T.
    Tijssen, Lars
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Prein, Andreas F.
    van Meijgaard, Erik
    Fealy, Rowan
    Jacob, Daniela
    Teichmann, Claas
    Future Changes in European Severe Convection Environments in a Regional Climate Model Ensemble2017In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 30, no 17, p. 6771-6794Article in journal (Refereed)
  • 346. Pulatov, Bakhtiyor
    et al.
    Jonsson, Anna Maria
    Wilcke, Renate
    SMHI, Research Department, Climate research - Rossby Centre.
    Linderson, Maj-Lena
    Hall, Karin
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluation of the phenological synchrony between potato crop and Colorado potato beetle under future climate in Europe2016In: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 224, p. 39-49Article in journal (Refereed)
  • 347. Qian, Minwei
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Laprise, Rene
    Caya, Daniel
    The Influences of NAO and the Hudson Bay sea-ice on the climate of eastern Canada2008In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 31, no 2-3, p. 169-182Article in journal (Refereed)
  • 348. Rafael, S.
    et al.
    Martins, Helena
    SMHI, Research Department, Climate research - Rossby Centre.
    Marta-Almeida, M.
    Sa, E.
    Coelho, S.
    Rocha, A.
    Borrego, C.
    Lopes, M.
    Quantification and mapping of urban fluxes under climate change: Application of WRF-SUEWS model to Greater Porto area (Portugal)2017In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 155, p. 321-334Article in journal (Refereed)
  • 349. Rafael, S.
    et al.
    Martins, Helena
    SMHI, Research Department, Climate research - Rossby Centre.
    Sa, E.
    Carvalho, D.
    Borrego, C.
    Lopes, M.
    Influence of urban resilience measures in the magnitude and behaviour of energy fluxes in the city of Porto (Portugal) under a climate change scenario2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 566, p. 1500-1510Article in journal (Refereed)
  • 350. Rammig, A.
    et al.
    Jonsson, A. M.
    Hickler, T.
    Smith, B.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Sykes, M. T.
    Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model2010In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 221, no 2, p. 303-313Article in journal (Refereed)
    Abstract [en]

    Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO(2) concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century. (C) 2009 Elsevier B.V. All rights reserved.

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