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  • 1. Akinsanola, A. A.
    et al.
    Ajayi, V. O.
    Adejare, A. T.
    Adeyeri, O. E.
    Gbode, I. E.
    Ogunjobi, K. O.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Abolude, A. T.
    Evaluation of rainfall simulations over West Africa in dynamically downscaled CMIP5 global circulation models2018Ingår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 132, nr 1-2, s. 437-450Artikel i tidskrift (Refereegranskat)
  • 2. Angel Gaertner, Miguel
    et al.
    Jesus Gonzalez-Aleman, Juan
    Romera, Raquel
    Dominguez, Marta
    Gil, Victoria
    Sanchez, Enrique
    Gallardo, Clemente
    Marcello Miglietta, Mario
    Walsh, Kevin J. E.
    Sein, Dmitry V.
    Somot, Samuel
    Dell'Aquila, Alessandro
    Teichmann, Claas
    Ahrens, Bodo
    Buonomo, Erasmo
    Colette, Augustin
    Bastin, Sophie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Simulation of medicanes over the Mediterranean Sea in a regional climate model ensemble: impact of ocean-atmosphere coupling and increased resolution2018Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 51, nr 3, s. 1041-1057Artikel i tidskrift (Refereegranskat)
  • 3. Casanueva, A.
    et al.
    Kotlarski, S.
    Herrera, S.
    Fernandez, J.
    Gutierrez, J. M.
    Boberg, F.
    Colette, A.
    Christensen, O. B.
    Goergen, K.
    Jacob, D.
    Keuler, K.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Teichmann, C.
    Vautard, R.
    Daily precipitation statistics in a EURO-CORDEX RCM ensemble: added value of raw and bias-corrected high-resolution simulations2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 47, nr 3-4, s. 719-737Artikel i tidskrift (Refereegranskat)
  • 4. Cerezo-Mota, Ruth
    et al.
    Cavazos, Tereza
    Arritt, Raymond
    Torres-Alavez, Abraham
    Sieck, Kevin
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Moufouma-Okia, Wilfram
    Antonio Salinas-Prieto, Jose
    CORDEX-NA: factors inducing dry/wet years on the North American Monsoon region2016Ingår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 36, nr 2, s. 824-836Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The output of four regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX)-North America (NA) region was analysed for the 1990-2008 period, with particular interest on the mechanisms associated with wet and dry years over the North American Monsoon (NAM) core region. All RCMs (RCA3.5, HadGEM3-RA, REMO, and RegCM4) were forced by the ERA-Interim reanalysis. Model precipitation was compared against several observational gridded data sets at different time scales. Most RCMs capture well the annual cycle of precipitation and outperform ERA-Interim, which is drier than the observations. RCMs underestimate (overestimate) the precipitation over the coastal plains (mountains) and have some problems to reproduce the interannual variability of the monsoon. To further investigate this, two extreme summers that showed the largest consistency among observations and RCMs were chosen: one wet (1990) and one dry (2005). The impact of the passage of tropical cyclones, the size of the Western Hemisphere Warm Pool (WHWP), the Intertropical Convergence Zone (ITCZ) position, and the initial intensity of the land-sea thermal contrast (LSTC) were analysed. During the wet year, the LSTC was stronger than the 2005 dry monsoon season and there were a larger number of hurricanes near the Gulf of California, the WHWP was more extended, and the ITCZ was located in a more northerly position than in 2005. All these processes contributed to a wetter NAM season. During the dry year, the LSTC was weaker, with a later onset, probably due to a previous very wet winter. The inverse precipitation relationship between winter and summer in the monsoon region was well captured by most of the RCMs. RegCM4 showed the largest biases and HadGEM3-RA the smallest ones.

  • 5. Endris, Hussen Seid
    et al.
    Lennard, Christopher
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Artan, Guleid A.
    Future changes in rainfall associated with ENSO, IOD and changes in the mean state over Eastern Africa2019Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, nr 3-4, s. 2029-2053Artikel i tidskrift (Refereegranskat)
  • 6. Endris, Hussen Seid
    et al.
    Lennard, Christopher
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Panitz, Hans-Juergen
    Teleconnection responses in multi-GCM driven CORDEX RCMs over Eastern Africa2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 9-10, s. 2821-2846Artikel i tidskrift (Refereegranskat)
  • 7. Endris, Hussen Seid
    et al.
    Omondi, Philip
    Jain, Suman
    Lennard, Christopher
    Hewitson, Bruce
    Chang'a, Ladislaus
    Awange, J. L.
    Dosio, Alessandro
    Ketiem, Patrick
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    Stordal, Frode
    Tazalika, Lukiya
    Assessment of the Performance of CORDEX Regional Climate Models in Simulating East African Rainfall2013Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, nr 21, s. 8453-8475Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This study evaluates the ability of 10 regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX) in simulating the characteristics of rainfall patterns over eastern Africa. The seasonal climatology, annual rainfall cycles, and interannual variability of RCM output have been assessed over three homogeneous subregions against a number of observational datasets. The ability of the RCMs in simulating large-scale global climate forcing signals is further assessed by compositing the El Nino-Southern Oscillation (ENSO) and Indian Ocean dipole (IOD) events. It is found that most RCMs reasonably simulate the main features of the rainfall climatology over the three subregions and also reproduce the majority of the documented regional responses to ENSO and IOD forcings. At the same time the analysis shows significant biases in individual models depending on subregion and season; however, the ensemble mean has better agreement with observation than individual models. In general, the analysis herein demonstrates that the multimodel ensemble mean simulates eastern Africa rainfall adequately and can therefore be used for the assessment of future climate projections for the region.

  • 8. Favre, Alice
    et al.
    Philippon, Nathalie
    Pohl, Benjamin
    Kalognomou, Evangelia-Anna
    Lennard, Christopher
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Dosio, Alessandro
    Panitz, Hans-Juergen
    Cerezo-Mota, Ruth
    Spatial distribution of precipitation annual cycles over South Africa in 10 CORDEX regional climate model present-day simulations2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 5-6, s. 1799-1818Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents an evaluation of the ability of 10 regional climate models (RCMs) participating in the COordinated Regional climate Downscaling Experiment-Africa to reproduce the present-day spatial distribution of annual cycles of precipitation over the South African region and its borders. As found in previous studies, annual mean precipitation is quasi-systematically overestimated by the RCMs over a large part of southern Africa south of about 20A degrees S and more strongly over South Africa. The spatial analysis of precipitation over the studied region shows that in most models the distribution of biases appears to be linked to orography. Wet biases are quasi-systematic in regions with higher elevation with inversely neutral to dry biases particularly in the coastal fringes. This spatial pattern of biases is particularly obvious during summer and specifically at the beginning of the rainy season (November and December) when the wet biases are found to be the strongest across all models. Applying a k-means algorithm, a classification of annual cycles is performed using observed precipitation data, and is compared with those derived from modeled data. It is found that the in-homogeneity of the spatial and temporal distribution of biases tends to impact the modeled seasonality of precipitation. Generally, the pattern of rainfall seasonality in the ensemble mean of the 10 RCMs tends to be shifted to the southwest. This spatial shift is mainly linked to a strong overestimation of convective precipitation at the beginning of the rainy season over the plateau inducing an early annual peak and to an underestimation of stratiform rainfall in winter and spring over southwestern South Africa.

  • 9. Gampe, David
    et al.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ludwig, Ralf
    Using an ensemble of regional climate models to assess climate change impacts on water scarcity in European river basins2016Ingår i: SCIENCE OF THE TOTAL ENVIRONMENT, ISSN 0048-9697, Vol. 573, s. 1503-1518Artikel i tidskrift (Refereegranskat)
  • 10.
    Gbobaniyi, Bode
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Sarr, Abdoulaye
    Sylla, Mouhamadou Bamba
    Diallo, Ismaila
    Lennard, Chris
    Dosio, Alessandro
    Dhiediou, Arona
    Kamga, Andre
    Klutse, Nana Ama Browne
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Lamptey, Benjamin
    Climatology, annual cycle and interannual variability of precipitation and temperature in CORDEX simulations over West Africa2014Ingår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 34, nr 7, s. 2241-2257Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    We examine the ability of an ensemble of 10 Regional Climate Models (RCMs), driven by ERA-Interim reanalysis, in skillfully reproducing key features of present-day precipitation and temperature (1990-2008) over West Africa. We explore a wide range of time scales spanning seasonal climatologies, annual cycles and interannual variability, and a number of spatial scales covering the Sahel, the Gulf of Guinea and the entire West Africa. We find that the RCMs show acceptable performance in simulating the spatial distribution of the main precipitation and temperature features. The occurrence of the West African Monsoon jump, the intensification and northward shift of the Saharan Heat Low (SHL), during the course of the year, are shown to be realistic in most RCMs. They also capture the mean annual cycle of precipitation and temperature, including, single and double-peaked rainy seasons, in terms of timing and amplitude over the homogeneous sub-regions. However, we should emphasize that the RCMs exhibit some biases, which vary considerably in both magnitude and spatial extent from model to model. The interannual variability of seasonal anomalies is best reproduced in temperature rather than precipitation. The ensemble mean considerably improves the skill of most of the individual RCMs. This highlights the importance of performing multi-model assessment in properly estimating the response of the West African climate to global warming at seasonal, annual and interannual time scales.

  • 11. Guettler, Ivan
    et al.
    Stepanov, Igor
    Brankovic, Cedo
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Impact of Horizontal Resolution on Precipitation in Complex Orography Simulated by the Regional Climate Model RCA3*2015Ingår i: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 143, nr 9, s. 3610-3627Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hydrostatic regional climate model RCA, version 3 (RCA3), of the Swedish Meteorological and Hydrological Institute was used to dynamically downscale ERA-40 and the ECMWF operational analysis over a 22-yr period. Downscaling was performed at four horizontal resolutions-50, 25, 12.5, and 6.25 km-over an identical European domain. The model-simulated precipitation is evaluated against high-resolution gridded observational precipitation datasets over Switzerland and southern Norway, regions that are characterized by complex orography and distinct climate regimes. RCA3 generally overestimates precipitation over high mountains: during winter and summer over Switzerland and during summer over central-southern Norway. In the summer, this is linked with a substantial contribution of convective precipitation to the total precipitation errors, especially at the coarser resolutions (50 and 25 km). A general improvement in spatial correlation coefficients between simulated and observed precipitation is observed when the horizontal resolution is increased from 50 to 6 km. The 95th percentile spatial correlation coefficients during winter are much higher for southern Norway than for Switzerland, indicating that RCA3 is more successful at reproducing a relatively simple west-to-east precipitation gradient over southern Norway than a much more complex and variable precipitation distribution over Switzerland. The 6-km simulation is not always superior to the other simulations, possibly indicating that the model dynamical and physical configuration at this resolution may not have been optimal. However, a general improvement in simulated precipitation with increasing resolution supports further use and application of high spatial resolutions in RCA3.

  • 12. Gutowski, William J., Jr.
    et al.
    Giorgi, Filippo
    Timbal, Bertrand
    Frigon, Anne
    Jacob, Daniela
    Kang, Hyun-Suk
    Raghavan, Krishnan
    Lee, Boram
    Lennard, Christopher
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    O'Rourke, Eleanor
    Rixen, Michel
    Solman, Silvina
    Stephenson, Tannecia
    Tangang, Fredolin
    WCRP COordinated Regional Downscaling EXperiment (CORDEX): a diagnostic MIP for CMIP62016Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 9, nr 11, s. 4087-4095Artikel i tidskrift (Refereegranskat)
  • 13. Iqbal, W.
    et al.
    Syed, F. S.
    Sajjad, H.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hannachi, A.
    Mean climate and representation of jet streams in the CORDEX South Asia simulations by the regional climate model RCA42017Ingår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 129, nr 1-2, s. 1-19Artikel i tidskrift (Refereegranskat)
  • 14. Jacob, Daniela
    et al.
    Petersen, Juliane
    Eggert, Bastian
    Alias, Antoinette
    Christensen, Ole Bossing
    Bouwer, Laurens M.
    Braun, Alain
    Colette, Augustin
    Deque, Michel
    Georgievski, Goran
    Georgopoulou, Elena
    Gobiet, Andreas
    Menut, Laurent
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Haensler, Andreas
    Hempelmann, Nils
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Keuler, Klaus
    Kovats, Sari
    Kroener, Nico
    Kotlarski, Sven
    Kriegsmann, Arne
    Martin, Eric
    van Meijgaard, Erik
    Moseley, Christopher
    Pfeifer, Susanne
    Preuschmann, Swantje
    Radermacher, Christine
    Radtke, Kai
    Rechid, Diana
    Rounsevell, Mark
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Somot, Samuel
    Soussana, Jean-Francois
    Teichmann, Claas
    Valentini, Riccardo
    Vautard, Robert
    Weber, Bjorn
    Yiou, Pascal
    EURO-CORDEX: new high-resolution climate change projections for European impact research2014Ingår i: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 14, nr 2, s. 563-578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new high-resolution regional climate change ensemble has been established for Europe within the World Climate Research Program Coordinated Regional Downscaling Experiment (EURO-CORDEX) initiative. The first set of simulations with a horizontal resolution of 12.5 km was completed for the new emission scenarios RCP4.5 and RCP8.5 with more simulations expected to follow. The aim of this paper is to present this data set to the different communities active in regional climate modelling, impact assessment and adaptation. The EURO-CORDEX ensemble results have been compared to the SRES A1B simulation results achieved within the ENSEMBLES project. The large-scale patterns of changes in mean temperature and precipitation are similar in all three scenarios, but they differ in regional details, which can partly be related to the higher resolution in EURO-CORDEX. The results strengthen those obtained in ENSEMBLES, but need further investigations. The analysis of impact indices shows that for RCP8.5, there is a substantially larger change projected for temperature-based indices than for RCP4.5. The difference is less pronounced for precipitation-based indices. Two effects of the increased resolution can be regarded as an added value of regional climate simulations. Regional climate model simulations provide higher daily precipitation intensities, which are completely missing in the global climate model simulations, and they provide a significantly different climate change of daily precipitation intensities resulting in a smoother shift from weak to moderate and high intensities.

  • 15. Jeong, Jee-Hoon
    et al.
    Walther, Alexander
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Chen, Deliang
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Diurnal cycle of precipitation amount and frequency in Sweden: observation versus model simulation2011Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, nr 4, s. 664-674Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigated the diurnal cycle of precipitation in Sweden using hourly ground observations for 1996-2008. General characteristics of phase and amplitude for the diurnal cycle of precipitation, both in amount and frequency, were identified. In the warm season (April-September), the 'typical' afternoon (14-16 LST) peaks are dominant over inland Sweden, whereas late night to early morning (04-06 LST) peaks with relatively weak amplitude are discernable in the east coast along the Baltic Sea. The diurnal variation is almost negligible in the cold season (October-March), due to the weak solar radiation at high latitudes. The variations of convective activity forced by solar heating and modulated by geographical characteristics were suggested as primarily factors to invoke the cycles and spatial variation identified. The observed cycle was compared with the cycle simulated by a regional climate model. The model fairly well captures the spatial pattern of the phase of the diurnal cycle. However, the warm season afternoon peak is simulated too early and too uniformly across the stations, associated with too frequent occurrences of convective rainfall events with relatively light intensity. These discrepancies point to the need to improve the convection parametrization and geographic representation of the model.

  • 16. Jerez, Sonia
    et al.
    Tobin, Isabelle
    Vautard, Robert
    Pedro Montavez, Juan
    Maria Lopez-Romero, Jose
    Thais, Francoise
    Bartok, Blanka
    Christensen, Ole Bossing
    Colette, Augustin
    Deque, Michel
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kotlarski, Sven
    van Meijgaard, Erik
    Teichmann, Claas
    Wild, Martin
    The impact of climate change on photovoltaic power generation in Europe2015Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, artikel-id 10014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ambitious climate change mitigation plans call for a significant increase in the use of renewables, which could, however, make the supply system more vulnerable to climate variability and changes. Here we evaluate climate change impacts on solar photovoltaic (PV) power in Europe using the recent EURO-CORDEX ensemble of high-resolution climate projections together with a PV power production model and assuming a well-developed European PV power fleet. Results indicate that the alteration of solar PV supply by the end of this century compared with the estimations made under current climate conditions should be in the range (-14%; +2%), with the largest decreases in Northern countries. Temporal stability of power generation does not appear as strongly affected in future climate scenarios either, even showing a slight positive trend in Southern countries. Therefore, despite small decreases in production expected in some parts of Europe, climate change is unlikely to threaten the European PV sector.

  • 17. Kalognomou, Evangelia-Anna
    et al.
    Lennard, Christopher
    Shongwe, Mxolisi
    Pinto, Izidine
    Favre, Alice
    Kent, Michael
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    A Diagnostic Evaluation of Precipitation in CORDEX Models over Southern Africa2013Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, nr 23, s. 9477-9506Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The authors evaluate the ability of 10 regional climate models (RCMs) to simulate precipitation over Southern Africa within the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework. An ensemble of 10 regional climate simulations and the ensemble average is analyzed to evaluate the models' ability to reproduce seasonal and interannual regional climatic features over regions of the subcontinent. All the RCMs use a similar domain, have a spatial resolution of 50 km, and are driven by the Interim ECMWF Re-Analysis (ERA-Interim; 1989-2008). Results are compared against a number of observational datasets.In general, the spatial and temporal nature of rainfall over the region is captured by all RCMs, although individual models exhibit wet or dry biases over particular regions of the domain. Models generally produce lower seasonal variability of precipitation compared to observations and the magnitude of the variability varies in space and time. Model biases are related to model setup, simulated circulation anomalies, and moisture transport. The multimodel ensemble mean generally outperforms individual models, with bias magnitudes similar to differences across the observational datasets. In the northern parts of the domain, some of the RCMs and the ensemble average improve the precipitation climate compared to that of ERA-Interim. The models are generally able to capture the dry (wet) precipitation anomaly associated with El Nino (La Nina) events across the region. Based on this analysis, the authors suggest that the present set of RCMs can be used to provide useful information on climate projections of rainfall over Southern Africa.

  • 18. Kamarainen, Matti
    et al.
    Hyvarinen, Otto
    Vajda, Andrea
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    van Meijgaard, Erik
    Teichmann, Claas
    Jacob, Daniela
    Gregow, Hilppa
    Jylha, Kirsti
    Estimates of Present-Day and Future Climatologies of Freezing Rain in Europe Based on CORDEX Regional Climate Models2018Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, nr 23, s. 13291-13304Artikel i tidskrift (Refereegranskat)
  • 19.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Boberg, Fredrik
    Castro, Manuel
    Christensen, Jens Hesselbjerg
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Sanchez, Enrique
    Daily and monthly temperature and precipitation statistics as performance indicators for regional climate models2010Ingår i: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 44, nr 2-3, s. 135-150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We evaluated daily and monthly statistics of maximum and minimum temperatures and precipitation in an ensemble of 16 regional climate models (RCMs) forced by boundary conditions from reanalysis data for 1961-1990. A high-resolution gridded observational data set for land areas in Europe was used. Skill scores were calculated based on the match of simulated and observed empirical probability density functions. The evaluation for different variables, seasons and regions showed that some models were better/worse than others in an overall sense. It also showed that no model that was best/worst in all variables, seasons or regions. Biases in daily precipitation were most pronounced in the wettest part of the probability distribution where the RCMs tended to overestimate precipitation compared to observations. We also applied the skill scores as weights used to calculate weighted ensemble means of the variables. We found that weighted ensemble means were slightly better in comparison to observations than corresponding unweighted ensemble means for most seasons, regions and variables. A number of sensitivity tests showed that the weights were highly sensitive to the choice of skill score metric and data sets involved in the comparison.

  • 20.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nilsson, Carin
    Lunds Universitet.
    Persson, Gunn
    SMHI, Affärsverksamhet.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Production and use of regional climate model projections – A Swedish perspective on building climate services2016Ingår i: Climate Services, ISSN 2405-8807, nr 2-3, s. 15-29Artikel i tidskrift (Refereegranskat)
  • 21.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Changes in seasonal mean European temperature and precipitation climate from an ensemble of transient RCM simulations driven by several AOGCMs2009Konferensbidrag (Övrigt vetenskapligt)
  • 22.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Climate change in the Baltic Sea area in an ensemble of regional climate model simulations2010Konferensbidrag (Övrigt vetenskapligt)
  • 23.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    An ensemble of regional climate change simulations2009Ingår i: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, s. 134-135Konferensbidrag (Övrigt vetenskapligt)
  • 24.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    21st century changes in the European climate: uncertainties derived from an ensemble of regional climate model simulations2011Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, nr 1, s. 24-40Artikel i tidskrift (Refereegranskat)
  • 25.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    21st century changes in the Nordic climate: 8ncertainties derived from an ensemble of regional climate model simulations2010Konferensbidrag (Övrigt vetenskapligt)
  • 26.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Seasonal mean temperature, precipitation and wind speed in Europe from an ensemble of 16 transient RCM simulations for 1961-21002010Ingår i: Geophysical Research Abstracts, 2010, Vol. 12, artikel-id EGU2010-10229Konferensbidrag (Refereegranskat)
  • 27.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Christensen, Ole Bossing
    Jacob, Daniela
    Keuler, Klaus
    Lenderink, Geert
    van Meijgaard, Erik
    Schar, Christoph
    Somot, Samuel
    Sorland, Silje Lund
    Teichmann, Claas
    Vautard, Robert
    European climate change at global mean temperature increases of 1.5 and 2 degrees C above pre-industrial conditions as simulated by the EURO-CORDEX regional climate models2018Ingår i: Earth System Dynamics, ISSN 2190-4979, E-ISSN 2190-4987, Vol. 9, nr 2, s. 459-478Artikel i tidskrift (Refereegranskat)
  • 28. Klutse, Nana Ama Browne
    et al.
    Ajayi, Vincent O.
    Gbobaniyi, Bode
    SMHI, Affärsverksamhet.
    Egbebiyi, Temitope S.
    Kouadio, Kouakou
    Nkrumah, Francis
    Quagraine, Kwesi Akumenyi
    Olusegun, Christiana
    Diasso, Ulrich
    Abiodun, Babatunde J.
    Lawal, Kamoru
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Lennard, Christopher
    Dosio, Alessandro
    Potential impact of 1.5 degrees C and 2 degrees C global warming on consecutive dry and wet days over West Africa2018Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, nr 5, artikel-id 055013Artikel i tidskrift (Refereegranskat)
  • 29. Klutse, Nana Ama Browne
    et al.
    Sylla, Mouhamadou Bamba
    Diallo, Ismaila
    Sarr, Abdoulaye
    Dosio, Alessandro
    Diedhiou, Arona
    Kamga, Andre
    Lamptey, Benjamin
    Ali, Abdou
    Gbobaniyi, Emiola O.
    Owusu, Kwadwo
    Lennard, Christopher
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    Daily characteristics of West African summer monsoon precipitation in CORDEX simulations2016Ingår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 123, nr 1-2, s. 369-386Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We analyze and intercompare the performance of a set of ten regional climate models (RCMs) along with the ensemble mean of their statistics in simulating daily precipitation characteristics during the West African monsoon (WAM) period (June-July-August-September). The experiments are conducted within the framework of the COordinated Regional Downscaling Experiments for the African domain. We find that the RCMs exhibit substantial differences that are associated with a wide range of estimates of higher-order statistics, such as intensity, frequency, and daily extremes mostly driven by the convective scheme employed. For instance, a number of the RCMs simulate a similar number of wet days compared to observations but greater rainfall intensity, especially in oceanic regions adjacent to the Guinea Highlands because of a larger number of heavy precipitation events. Other models exhibit a higher wet-day frequency but much lower rainfall intensity over West Africa due to the occurrence of less frequent heavy rainfall events. This indicates the existence of large uncertainties related to the simulation of daily rainfall characteristics by the RCMs. The ensemble mean of the indices substantially improves the RCMs' simulated frequency and intensity of precipitation events, moderately outperforms that of the 95th percentile, and provides mixed benefits for the dry and wet spells. Although the ensemble mean improved results cannot be generalized, such an approach produces encouraging results and can help, to some extent, to improve the robustness of the response of the WAM daily precipitation to the anthropogenic greenhouse gas warming.

  • 30. Knist, Sebastian
    et al.
    Goergen, Klaus
    Buonomo, Erasmo
    Christensen, Ole Bossing
    Colette, Augustin
    Cardoso, Rita M.
    Fealy, Rowan
    Fernandez, Jesus
    Garcia-Diez, Markel
    Jacob, Daniela
    Kartsios, Stergios
    Katragkou, Eleni
    Keuler, Klaus
    Mayer, Stephanie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Soares, Pedro M. M.
    Sobolowski, Stefan
    Szepszo, Gabriella
    Teichmann, Claas
    Vautard, Robert
    Warrach-Sagi, Kirsten
    Wulfmeyer, Volker
    Simmer, Clemens
    Land-atmosphere coupling in EURO-CORDEX evaluation experiments2017Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 122, nr 1, s. 79-103Artikel i tidskrift (Refereegranskat)
  • 31.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Regional Arctic sea ice variations as predictor for winter climate conditions2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 1-2, s. 317-337Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO-negative after low ice-but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes.

  • 32.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Arctic future scenario experiments with a coupled regional climate model2011Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, nr 1, s. 69-86Artikel i tidskrift (Refereegranskat)
  • 33. Kotlarski, S.
    et al.
    Keuler, K.
    Christensen, O. B.
    Colette, A.
    Deque, M.
    Gobiet, A.
    Goergen, K.
    Jacob, D.
    Luethi, D.
    van Meijgaard, E.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schaer, C.
    Teichmann, C.
    Vautard, R.
    Warrach-Sagi, K.
    Wulfmeyer, V.
    Regional climate modeling on European scales: a joint standard evaluation of the EURO-CORDEX RCM ensemble2014Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 7, nr 4, s. 1297-1333Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    EURO-CORDEX is an international climate downscaling initiative that aims to provide high-resolution climate scenarios for Europe. Here an evaluation of the ERA-Interim-driven EURO-CORDEX regional climate model (RCM) ensemble is presented. The study documents the performance of the individual models in representing the basic spatiotemporal patterns of the European climate for the period 1989-2008. Model evaluation focuses on near-surface air temperature and precipitation, and uses the E-OBS data set as observational reference. The ensemble consists of 17 simulations carried out by seven different models at grid resolutions of 12 km (nine experiments) and 50 km (eight experiments). Several performance metrics computed from monthly and seasonal mean values are used to assess model performance over eight subdomains of the European continent. Results are compared to those for the ERA40-driven ENSEMBLES simulations. The analysis confirms the ability of RCMs to capture the basic features of the European climate, including its variability in space and time. But it also identifies nonnegligible deficiencies of the simulations for selected metrics, regions and seasons. Seasonally and regionally averaged temperature biases are mostly smaller than 1.5 degrees C, while precipitation biases are typically located in the +/- 40% range. Some bias characteristics, such as a predominant cold and wet bias in most seasons and over most parts of Europe and a warm and dry summer bias over southern and southeastern Europe reflect common model biases. For seasonal mean quantities averaged over large European subdomains, no clear benefit of an increased spatial resolution (12 vs. 50 km) can be identified. The bias ranges of the EURO-CORDEX ensemble mostly correspond to those of the ENSEMBLES simulations, but some improvements in model performance can be identified (e. g., a less pronounced southern European warm summer bias). The temperature bias spread across different configurations of one individual model can be of a similar magnitude as the spread across different models, demonstrating a strong influence of the specific choices in physical parameterizations and experimental setup on model performance. Based on a number of simply reproducible metrics, the present study quantifies the currently achievable accuracy of RCMs used for regional climate simulations over Europe and provides a quality standard for future model developments.

  • 34. Kuttippurath, J.
    et al.
    Godin-Beekmann, S.
    Lefevre, F.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Santee, M. L.
    Froidevaux, L.
    Record-breaking ozone loss in the Arctic winter 2010/2011: comparison with 1996/19972012Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, nr 15, s. 7073-7085Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed discussion of the chemical and dynamical processes in the Arctic winters 1996/1997 and 2010/2011 with high resolution chemical transport model (CTM) simulations and space-based observations. In the Arctic winter 2010/2011, the lower stratospheric minimum temperatures were below 195K for a record period of time, from December to mid-April, and a strong and stable vortex was present during that period. Simulations with the Mimosa-Chim CTM show that the chemical ozone loss started in early January and progressed slowly to 1 ppmv (parts per million by volume) by late February. The loss intensified by early March and reached a record maximum of similar to 2.4 ppmv in the late March-early April period over a broad altitude range of 450-550 K. This coincides with elevated ozone loss rates of 2-4 ppbv sh(-1) (parts per billion by volume/sunlit hour) and a contribution of about 30-55% and 30-35% from the ClO-ClO and ClO-BrO cycles, respectively, in late February and March. In addition, a contribution of 30-50% from the HOx cycle is also estimated in April. We also estimate a loss of about 0.7-1.2 ppmv contributed (75%) by the NOx cycle at 550-700 K. The ozone loss estimated in the partial column range of 350-550K exhibits a record value of similar to 148DU (Dobson Unit). This is the largest ozone loss ever estimated in the Arctic and is consistent with the remarkable chlorine activation and strong denitrification (40-50%) during the winter, as the modeled ClO shows similar to 1.8 ppbv in early January and similar to 1 ppbv in March at 450-550 K. These model results are in excellent agreement with those found from the Aura Microwave Limb Sounder observations. Our analyses also show that the ozone loss in 2010/2011 is close to that found in some Antarctic winters, for the first time in the observed history. Though the winter 1996/1997 was also very cold in March-April, the temperatures were higher in December-February, and, therefore, chlorine activation was moderate and ozone loss was average with about 1.2 ppmv at 475-550K or 42DU at 350-550 K, as diagnosed from the model simulations and measurements.

  • 35. Kuttippurath, J.
    et al.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    A comparative study of the major sudden stratospheric warmings in the Arctic winters 2003/2004-2009/20102012Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, nr 17, s. 8115-8129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an analysis of the major sudden stratospheric warmings (SSWs) in the Arctic winters 2003/04-2009/10. There were 6 major SSWs (major warmings [MWs]) in 6 out of the 7 winters, in which the MWs of 2003/04, 2005/06, and 2008/09 were in January and those of 2006/07, 2007/08, and 2009/10 were in February. Although the winter 2009/10 was relatively cold from mid-December to mid-January, strong wave 1 activity led to a MW in early February, for which the largest momentum flux among the winters was estimated at 60 degrees N/10 hPa, about 450 m(2) s(-2). The strongest MW, however, was observed in 2008/09 and the weakest in 2006/07. The MW in 2008/09 was triggered by intense wave 2 activity and was a vortex split event. In contrast, strong wave 1 activity led to the MWs of other winters and were vortex displacement events. Large amounts of Eliassen-Palm (EP) and wave 1/2 EP fluxes (about 2-4x10(5) kg s-2) are estimated shortly before the MWs at 100 hPa averaged over 45-75 degrees N in all winters, suggesting profound tropospheric forcing for the MWs. We observe an increase in the occurrence of MWs (similar to 1.1 MWs/winter) in recent years (1998/99-2009/10), as there were 13MWs in the 12 Arctic winters, although the long-term average (1957/58-2009/10) of the frequency stays around its historical value (similar to 0.7 MWs/winter), consistent with the findings of previous studies. An analysis of the chemical ozone loss in the past 17 Arctic winters (1993/94-2009/10) suggests that the loss is inversely proportional to the intensity and timing of MWs in each winter, where early (December-January) MWs lead to minimal ozone loss. Therefore, this high frequency of MWs in recent Arctic winters has significant implications for stratospheric ozone trends in the northern hemisphere.

  • 36. Kuttippurath, Jayanarayanan
    et al.
    Kleinboehl, Armin
    Sinnhuber, Miriam
    Bremer, Holger
    Kuellmann, Harry
    Notholt, Justus
    Godin-Beekmann, Sophie
    Tripathi, Omprakash
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Arctic ozone depletion in 2002-2003 measured by ASUR and comparison with POAM observations2011Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 116, artikel-id D22305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present ozone loss estimated from airborne measurements taken during January-February and March in the Arctic winter 2002/2003. The first half of the winter was characterized by unusually cold temperatures and the second half by a major stratospheric sudden warming around 15-18 January 2003. The potential vorticity maps show a vortex split in the lower stratosphere during the major warming (MW) in late January and during the minor warming in mid-February due to wave 1 amplification. However, the warming can be termed as a vortex displacement event as there was no vortex split during the MW period at 10 hPa. Very low temperatures, large areas of polar stratospheric clouds (PSCs), and high chlorine activation triggered significant ozone loss in the early winter, as the vortex moved to the midlatitude regions. The ozone depletion derived from the ASUR measurements sampled inside the vortex, in conjunction with the Mimosa-Chim model tracer, shows a maximum of 1.3 +/- 0.2 ppmv at 450-500 K by late March. The partial column loss derived from the ASUR ozone profiles reaches up to 61 +/- 4 DU in 400-550 K in the same period. The evolution of ozone and ozone loss assessed from the ASUR measurements is in very good agreement with POAM observations. The reduction in ozone estimated from the POAM measurements shows a similar maximum of 1.3 +/- 0.2 ppmv at 400-500 K or 63 +/- 4 DU in 400-550 K in late March. Our study reveals that the Arctic winter 2002/2003 was unique as it had three minor warmings and a MW, yet showed large loss in ozone. No such feature was observed in any other Arctic winter in the 1989-2010 period. In addition, an unusually large ozone loss in December, around 0.5 +/- 0.2 ppmv at 450-500 K or 12 +/- 1 DU in 400-550 K, was estimated for the first time in the Arctic. A careful and detailed diagnosis with all available published results for this winter exhibits an average ozone loss of 1.5 +/- 0.3 ppmv at 450-500 K or 65 +/- 5 DU in 400-550 K by the end of March, which exactly matches the ozone depletion derived from the ASUR, POAM and model data. The early ozone loss together with considerable loss afterwards put the warm Arctic winter 2002/2003 amongst the moderately cold winters in terms of the significance of the ozone loss.

  • 37. Laiti, L.
    et al.
    Mallucci, S.
    Piccolroaz, S.
    Bellin, A.
    Zardi, D.
    Fiori, A.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Majone, B.
    Testing the Hydrological Coherence of High-Resolution Gridded Precipitation and Temperature Data Sets2018Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 54, nr 3, s. 1999-2016Artikel i tidskrift (Refereegranskat)
  • 38. Leedale, Joseph
    et al.
    Tompkins, Adrian M.
    Caminade, Cyril
    Jones, Anne E.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Morse, Andrew P.
    Projecting malaria hazard from climate change in eastern Africa using large ensembles to estimate uncertainty2016Ingår i: GEOSPATIAL HEALTH, ISSN 1827-1987, Vol. 11, s. 102-114Artikel i tidskrift (Refereegranskat)
  • 39. Lennard, C. J.
    et al.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Dosio, A.
    Moufouma-Okia, W.
    On the need for regional climate information over Africa under varying levels of global warming2018Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, nr 6, artikel-id 060401Artikel i tidskrift (Refereegranskat)
  • 40. Maure, G.
    et al.
    Pinto, I.
    Ndebele-Murisa, M.
    Muthige, M.
    Lennard, C.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Dosio, A.
    Meque, A.
    The southern African climate under 1.5 degrees C and 2 degrees C of global warming as simulated by CORDEX regional climate models2018Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, nr 6, artikel-id 065002Artikel i tidskrift (Refereegranskat)
  • 41. Mba, Wilfried Pokam
    et al.
    Longandjo, Georges-Noel T.
    Moufouma-Okia, Wilfran
    Bell, Jean-Pierre
    James, Rachel
    Vondou, Derbetini A.
    Haensler, Andreas
    Fotso-Nguemo, Thierry C.
    Guenang, Guy Merlin
    Tchotchou, Angennes Lucie Djiotang
    Kamsu-Tamo, Pierre H.
    Takong, Ridick R.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Lennard, Christopher J.
    Dosio, Alessandro
    Consequences of 1.5 degrees C and 2 degrees C global warming levels for temperature and precipitation changes over Central Africa2018Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, nr 5, artikel-id 055011Artikel i tidskrift (Refereegranskat)
  • 42. McCreesh, Nicky
    et al.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Booth, Mark
    Predicting the effects of climate change on Schistosoma mansoni transmission in eastern Africa2015Ingår i: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 8, artikel-id 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Survival and fitness attributes of free-living and sporocyst schistosome life-stages and their intermediate host snails are sensitive to water temperature. Climate change may alter the geographical distribution of schistosomiasis by affecting the suitability of freshwater bodies for hosting parasite and snail populations. Methods: We have developed an agent-based model of the temperature-sensitive stages of the Schistosoma mansoni and intermediate host snail lifecycles. The model was run using low, moderate and high warming climate projections over eastern Africa. For each climate projection, eight model scenarios were used to determine the sensitivity of predictions to different relationships between air and water temperature, and different snail mortality rates. Maps were produced showing predicted changes in risk as a result of increasing temperatures over the next 20 and 50 years. Results: Baseline model output compared to prevalence data indicates suitable temperatures are necessary but not sufficient for both S. mansoni transmission and high infection prevalences. All else being equal, infection risk may increase by up to 20% over most of eastern Africa over the next 20 and 50 years. Increases may be higher in Rwanda, Burundi, south-west Kenya and eastern Zambia, and S. mansoni may become newly endemic in some areas. Results for 20-year projections are robust to changes in simulated intermediate host snail habitat conditions. There is greater uncertainty about the effects of different habitats on changes in risk in 50 years' time. Conclusions: Temperatures are likely to become suitable for increased S. mansoni transmission over much of eastern Africa. This may reduce the impact of control and elimination programmes. S. mansoni may also spread to new areas outside existing control programmes. We call for increased surveillance in areas defined as potentially suitable for emergent transmission.

  • 43. Navarro-Ortega, Alicia
    et al.
    Acuna, Vicenc
    Bellin, Alberto
    Burek, Peter
    Cassiani, Giorgio
    Choukr-Allah, Redouane
    Doledec, Sylvain
    Elosegi, Arturo
    Ferrari, Federico
    Ginebreda, Antoni
    Grathwohl, Peter
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Rault, Philippe Ker
    Kok, Kasper
    Koundouri, Phoebe
    Ludwig, Ralf Peter
    Merz, Ralf
    Milacic, Radmila
    Munoz, Isabel
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Paniconi, Claudio
    Paunovic, Momir
    Petrovic, Mira
    Sabater, Laia
    Sabater, Sergi
    Skoulikidis, Nikolaos Th.
    Slob, Adriaan
    Teutsch, Georg
    Voulvoulis, Nikolaos
    Barcelo, Damia
    Managing the effects of multiple stressors on aquatic ecosystems under water scarcity. The GLOBAQUA project2015Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 503, s. 3-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Water scarcity is a serious environmental problem in many European regions, and will likely increase in the near future as a consequence of increased abstraction and climate change. Water scarcity exacerbates the effects of multiple stressors, and thus results in decreased water quality. It impacts river ecosystems, threatens the services they provide, and it will force managers and policy-makers to change their current practices. The EU-FP7 project GLOBAQUA aims at identifying the prevalence, interaction and linkages between stressors, and to assess their effects on the chemical and ecological status of freshwater ecosystems in order to improve water management practice and policies. GLOBAQUA assembles a multidisciplinary team of 21 European plus 2 non-European scientific institutions, as well as water authorities and river basin managers. The project includes experts in hydrology, chemistry, biology, geomorphology, modelling, socio-economics, governance science, knowledge brokerage, and policy advocacy. GLOBAQUA studies six river basins (Ebro, Adige, Sava, Evrotas, Anglian and Souss Massa) affected by water scarcity, and aims to answer the following questions: how does water scarcity interact with other existing stressors in the study river basins? How will these interactions change according to the different scenarios of future global change? Which will be the foreseeable consequences for river ecosystems? How will these in turn affect the services the ecosystems provide? How should management and policies be adapted to minimise the ecological, economic and societal consequences? These questions will be approached by combining data-mining, field- and laboratory-based research, and modelling. Here, we outline the general structure of the project and the activities to be conducted within the fourteen work-packages of GLOBAQUA. (C) 2014 The Authors. Published by Elsevier B.V.

  • 44.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Giorgi, Filippo
    Asrar, Ghassem
    Buechner, Matthias
    Cerezo-Mota, Ruth
    Christensen, Ole Bossing
    Deque, Michel
    Fernandez, Jesus
    Haensler, Andreas
    van Meijgaard, Erik
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Sylla, Mouhamadou Bamba
    Sushama, Laxmi
    Precipitation Climatology in an Ensemble of CORDEX-Africa Regional Climate Simulations2012Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 25, nr 18, s. 6057-6078Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An ensemble of regional climate simulations is analyzed to evaluate the ability of 10 regional climate models (RCMs) and their ensemble average to simulate precipitation over Africa. All RCMs use a similar domain and spatial resolution of similar to 50 km and are driven by the ECMWF Interim Re-Analysis (ERA-Interim) (1989-2008). They constitute the first set of simulations in the Coordinated Regional Downscaling Experiment in Africa (CORDEX-Africa) project. Simulated precipitation is evaluated at a range of time scales, including seasonal means, and annual and diurnal cycles, against a number of detailed observational datasets. All RCMs simulate the seasonal mean and annual cycle quite accurately, although individual models can exhibit significant biases in some subregions and seasons. The multimodel average generally outperforms any individual simulation, showing biases of similar magnitude to differences across a number of observational datasets. Moreover, many of the RCMs significantly improve the precipitation climate compared to that from their boundary condition dataset, that is, ERA-Interim. A common problem in the majority of the RCMs is that precipitation is triggered too early during the diurnal cycle, although a small subset of models does have a reasonable representation of the phase of the diurnal cycle. The systematic bias in the diurnal cycle is not improved when the ensemble mean is considered. Based on this performance analysis, it is assessed that the present set of RCMs can be used to provide useful information on climate projections over Africa.

  • 45.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Evaluation of temperature extremes from an ensemble of transient RCM simulations driven by several AOGCMs2009Konferensbidrag (Övrigt vetenskapligt)
  • 46.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Changes in daily temperature variability over Europe from an ensemble of RCM simulations driven by several AOGCMs2009Konferensbidrag (Övrigt vetenskapligt)
  • 47.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Changes in daily temperature variability over Europe from an ensemble of regional climate simulations driven by several AOGCMs.2009Konferensbidrag (Övrigt vetenskapligt)
  • 48.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Intraseasonal temperature variability over Europe in a future climate scenario2008Ingår i: Abstracts of the contributions of the EGU General Assembly 2008., 2008, Vol. 10, artikel-id EGU2008-A-09248Konferensbidrag (Övrigt vetenskapligt)
  • 49.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Projected changes in daily temperature variability over Europe in an ensemble of RCM simulations2009Konferensbidrag (Övrigt vetenskapligt)
  • 50.
    Nikulin, Grigory
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nordic weather extremes as simulated by the Rossby Centre Regional Climate Model: model evaluation and future projections2010Konferensbidrag (Övrigt vetenskapligt)
12 1 - 50 av 77
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