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| 2. |
- Döscher, Ralf, et al.
(författare)
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The EC-Earth3 Earth system model for the Coupled Model Intercomparison Project 6
- 2022
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Ingår i: Geoscientific Model Development. - : Copernicus GmbH. - 1991-959X .- 1991-9603. ; 15:7, s. 2973-3020
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Tidskriftsartikel (refereegranskat)abstract
- The Earth system model EC-Earth3 for contributions to CMIP6 is documented here, with its flexible coupling framework, major model configurations, a methodology for ensuring the simulations are comparable across different high-performance computing (HPC) systems, and with the physical performance of base configurations over the historical period. The variety of possible configurations and sub-models reflects the broad interests in the EC-Earth community. EC-Earth3 key performance metrics demonstrate physical behavior and biases well within the frame known from recent CMIP models. With improved physical and dynamic features, new Earth system model (ESM) components, community tools, and largely improved physical performance compared to the CMIP5 version, EC-Earth3 represents a clear step forward for the only European community ESM. We demonstrate here that EC-Earth3 is suited for a range of tasks in CMIP6 and beyond.
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| 3. |
- Guerova, G., et al.
(författare)
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National Status Reports
- 2020
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Ingår i: Advanced GNSS Tropospheric Products for Monitoring Severe Weather Events and Climate. - Cham : Springer International Publishing. - 9783030139001 ; , s. 403-481
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In this section a summary of the national progress reports is given. GNSS4SWEC Management Committee (MC) members provided outline of the work conducted in their countries combining input from different partners involved. In the COST Action paticipated member from 32 COST countries, 1 Near Neighbour Country and 8 Intrantional Partners from Australia, Canada, Hong Kong and USA. The text reflects the state as of 1 January 2018.
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| 6. |
- Koenigk, Torben, et al.
(författare)
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Arctic climate change in 21st century CMIP5 simulations with EC-Earth
- 2012
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Ingår i: Climate Dynamics. - : Springer-Verlag New York. - 0930-7575 .- 1432-0894. ; 40:11-12
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic climate change is analyzed in anensemble of future projection simulations performed withthe global coupled climate model EC-Earth2.3. EC-Earthsimulates the twentieth century Arctic climate relativelywell but the Arctic is about 2 K too cold and the sea icethickness and extent are overestimated. In the twenty-firstcentury, the results show a continuation and strengtheningof the Arctic trends observed over the recent decades,which leads to a dramatically changed Arctic climate,especially in the high emission scenario RCP8.5. Theannually averaged Arctic mean near-surface temperatureincreases by 12 K in RCP8.5, with largest warming in theBarents Sea region. The warming is most pronounced inwinter and autumn and in the lower atmosphere. The Arcticwinter temperature inversion is reduced in all scenarios anddisappears in RCP8.5. The Arctic becomes ice free inSeptember in all RCP8.5 simulations after a rapid reductionevent without recovery around year 2060. Taking intoaccount the overestimation of ice in the twentieth century,our model results indicate a likely ice-free Arctic inSeptember around 2040. Sea ice reductions are most pronouncedin the Barents Sea in all RCPs, which lead to themost dramatic changes in this region. Here, surface heatfluxes are strongly enhanced and the cloudiness is substantiallydecreased. The meridional heat flux into theArctic is reduced in the atmosphere but increases in theocean. This oceanic increase is dominated by an enhancedheat flux into the Barents Sea, which strongly contributes tothe large sea ice reduction and surface-air warming in thisregion. Increased precipitation and river runoff lead to morefreshwater input into the Arctic Ocean. However, most ofthe additional freshwater is stored in the Arctic Ocean whilethe total Arctic freshwater export only slightly increases.
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| 7. |
- Loeb, Norman G., et al.
(författare)
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New Generation of Climate Models Track Recent Unprecedented Changes in Earth's Radiation Budget Observed by CERES
- 2020
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 47:5
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Tidskriftsartikel (refereegranskat)abstract
- We compare top-of-atmosphere (TOA) radiative fluxes observed by the Clouds and the Earth's Radiant Energy System (CERES) and simulated by seven general circulation models forced with observed sea-surface temperature (SST) and sea-ice boundary conditions. In response to increased SSTs along the equator and over the eastern Pacific (EP) following the so-called global warming hiatus of the early 21st century, simulated TOA flux changes are remarkably similar to CERES. Both show outgoing shortwave and longwave TOA flux changes that largely cancel over the west and central tropical Pacific, and large reductions in shortwave flux for EP low-cloud regions. A model's ability to represent changes in the relationship between global mean net TOA flux and surface temperature depends upon how well it represents shortwave flux changes in low-cloud regions, with most showing too little sensitivity to EP SST changes, suggesting a pattern effect that may be too weak compared to observations.
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| 8. |
- Ning, Tong, 1975, et al.
(författare)
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Atmospheric Water Vapor Content Inferred From GPS Data and Compared to a Global NWP Model and a Regional Climate Model
- 2008
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Ingår i: 2008.10.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Radio based space geodetic methods are affected by the water vapor in the atmosphere.The velocity of the propagating signal is reduced, depending on the value of the refractiveindex. The atmospheric water vapor content, sometimes also called Integrated WaterVapor (IWV), can be inferred from the estimated propagation delay, or the excess propagationpath often expressed in units of length. The observations are relative measurementsof time, which makes the methods interesting from a calibration point of view - since timeis the physical parameter that we can measure with the highest accuracy.Since water vapor is difficult, and costly, to measure with a high temporal and spatialresolution, given its characteristics of variability, researchers in the atmospheric scienceshave shown interest in using data from already existing ground-based continuously operatingGPS receivers. Time series of the IWV from specific sites are now longer than tenyears. For example, 20 sites in the Swedish GPS network have produced continuous datasince 1993/1994. In addition to GPS also additional global navigational satellite systems(GNSS), such as the European Galileo and the finalization of the Russian GLONASS, willin the future significantly improve the spatial sampling of the atmosphere, and also reducethe relative influence of orbit errors for individual satellites.We have analyzed ground-based GPS data acquired in Europe and Africa over the period2001-2006. IWV results from the GPS data analysis are compared to the global NumericalWeather Prediction (NWP) models from the European Center for Medium RangeWeatherForecasting (ECMWF) as well as the regional climate model of the Rossby Center.The overall goal for the possible use of GNSS data in climate research is to determine towhich extent these independent data can be used to discriminate between different climatemodels - both in terms of absolute values as well as long term trends - thereby improvingthe quality of the models and increasing the probability to produce realistic scenarios ofthe future climate.
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| 9. |
- Ning, Tong, 1975, et al.
(författare)
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Evaluation of the atmospheric water vapor content in a regional climate model using ground-based GPS measurements
- 2013
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 118:2, s. 329-339
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Ning, Tong, 1975, et al.
(författare)
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Multi-technique comparisons of 10 years of wet delay estimates on the west coast of Sweden
- 2012
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Ingår i: Journal of Geodesy. - : Springer Science and Business Media LLC. - 0949-7714 .- 1432-1394. ; 86:7, s. 565-575
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Forskningsöversikt (refereegranskat)abstract
- 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 ∼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.
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