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Yang, Wei
Publications (10 of 15) Show all publications
Berg, P., Christensen, O. B., Klehmet, K., Lenderink, G., Olsson, J., Teichmann, C. & Yang, W. (2019). Summertime precipitation extremes in a EURO-CORDEX 0.11 degrees ensemble at an hourly resolution. Natural hazards and earth system sciences, 19(4), 957-971
Open this publication in new window or tab >>Summertime precipitation extremes in a EURO-CORDEX 0.11 degrees ensemble at an hourly resolution
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2019 (English)In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 19, no 4, p. 957-971Article in journal (Refereed) Published
National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-5205 (URN)10.5194/nhess-19-957-2019 (DOI)000466793900001 ()
Available from: 2019-05-21 Created: 2019-05-21 Last updated: 2019-05-21Bibliographically approved
Olsson, J., Berg, P., Eronn, A., Simonsson, L., Södling, J., Wern, L. & Yang, W. (2018). Extremregn i nuvarande och framtida klimat Analyser av observationer och framtidsscenarier.
Open this publication in new window or tab >>Extremregn i nuvarande och framtida klimat Analyser av observationer och framtidsscenarier
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2018 (Swedish)Report (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.

Publisher
p. 367
Series
Climatology, ISSN 1654-2258 ; 47
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-4505 (URN)
Available from: 2018-02-22 Created: 2018-02-22 Last updated: 2018-02-22Bibliographically approved
Olsson, J., Arheimer, B., Borris, M., Donnelly, C., Foster, K., Nikulin, G., . . . Yang, W. (2016). Hydrological Climate Change Impact Assessment at Small and Large Scales: Key Messages from Recent Progress in Sweden. CLIMATE, 4(3), Article ID 39.
Open this publication in new window or tab >>Hydrological Climate Change Impact Assessment at Small and Large Scales: Key Messages from Recent Progress in Sweden
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2016 (English)In: CLIMATE, ISSN 2225-1154, Vol. 4, no 3, article id 39Article in journal (Refereed) Published
National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-3255 (URN)10.3390/cli4030039 (DOI)000382625300006 ()
Available from: 2016-10-04 Created: 2016-10-04 Last updated: 2018-01-14Bibliographically approved
Olsson, J., Arheimer, B., Borris, M., Donnelly, C., Foster, K., Nikulin, G., . . . Yang, W. (2016). Hydrological Climate Change Impact Assessment at Small and Large Scales: Recent Progress and Current Issues.. Climate, 4(3)(39)
Open this publication in new window or tab >>Hydrological Climate Change Impact Assessment at Small and Large Scales: Recent Progress and Current Issues.
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2016 (English)In: Climate, ISSN 2225-1154, Vol. 4(3), no 39Article in journal (Refereed) Published
National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-3928 (URN)10.3390/cli4030039 (DOI)
Available from: 2017-02-22 Created: 2017-02-22 Last updated: 2018-01-13Bibliographically approved
Olsson, J., Uvo, C. B., Foster, K. & Yang, W. (2016). Technical Note: Initial assessment of a multi-method approach to spring-flood forecasting in Sweden. Hydrology and Earth System Sciences, 20(2), 659-667
Open this publication in new window or tab >>Technical Note: Initial assessment of a multi-method approach to spring-flood forecasting in Sweden
2016 (English)In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 20, no 2, p. 659-667Article in journal (Refereed) Published
Abstract [en]

Hydropower is a major energy source in Sweden, and proper reservoir management prior to the spring-flood onset is crucial for optimal production. This requires accurate forecasts of the accumulated discharge in the spring-flood period (i.e. the spring-flood volume, SFV). Today's SFV forecasts are generated using a model-based climatological ensemble approach, where time series of precipitation and temperature from historical years are used to force a calibrated and initialized set-up of the HBV model. In this study, a number of new approaches to spring-flood forecasting that reflect the latest developments with respect to analysis and modelling on seasonal timescales are presented and evaluated. Three main approaches, represented by specific methods, are evaluated in SFV hindcasts for the Swedish river Vindelalven over a 10-year period with lead times between 0 and 4 months. In the first approach, historically analogue years with respect to the climate in the period preceding the spring flood are identified and used to compose a reduced ensemble. In the second, seasonal meteorological ensemble forecasts are used to drive the HBV model over the spring-flood period. In the third approach, statistical relationships between SFV and the large-sale atmospheric circulation are used to build forecast models. None of the new approaches consistently outperform the climatological ensemble approach, but for early forecasts improvements of up to 25% are found. This potential is reasonably well realized in a multi-method system, which over all forecast dates reduced the error in SFV by similar to 4 %. This improvement is limited but potentially significant for e.g. energy trading.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-2195 (URN)10.5194/hess-20-659-2016 (DOI)000377697600006 ()
Available from: 2016-07-08 Created: 2016-07-08 Last updated: 2018-01-10Bibliographically approved
Wilk, J., Hjerpe, M., Yang, W. & Fan, H. (2015). Farm-scale adaptation under extreme climate and rapid economic transition. Environment, Development and Sustainability, 17(3), 393-407
Open this publication in new window or tab >>Farm-scale adaptation under extreme climate and rapid economic transition
2015 (English)In: Environment, Development and Sustainability, ISSN 1387-585X, E-ISSN 1573-2975, Vol. 17, no 3, p. 393-407Article in journal (Refereed) Published
Abstract [en]

This paper aims to analyse what shapes farmers' vulnerability and adaptation strategies in the context of rapid change. Xinjiang is semi-arid, with extremes of temperature, growing seasons and winds. Favourable socioeconomic conditions have boosted the wellbeing of farmers in the past decades. Interviews with forty-seven farmers led to the categorization of five groups according to the predominant type of farming activity: animal farmers, government farmers (leasing land from the Xinjiang Production and Construction Group), crop farmers, agri-tourism operators and entrepreneurs. High government support has aided farmers to deal with climate challenges, through advanced technology, subsidies and loans. Farmers, however, greatly contribute to their own high adaptive capacity through inventiveness, flexibility and a high knowledge base. Although the future climate will entail hotter temperatures, farmers can be seen as generally well equipped to deal with these challenges because of the high adaptive capacity they currently have and utilize. Those that are most vulnerable are those that have difficulty to access credit e.g. animal farmers and those that do not want to change their agricultural systems e.g. from pastoral lifestyles to include tourism-based operations.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-1978 (URN)10.1007/s10668-014-9549-2 (DOI)000354481200002 ()
Available from: 2016-04-26 Created: 2016-03-03 Last updated: 2018-01-10Bibliographically approved
Berg, P., Bosshard, T. & Yang, W. (2015). Model Consistent Pseudo-Observations of Precipitation and Their Use for Bias Correcting Regional Climate Models. CLIMATE, 3(1), 118-132
Open this publication in new window or tab >>Model Consistent Pseudo-Observations of Precipitation and Their Use for Bias Correcting Regional Climate Models
2015 (English)In: CLIMATE, ISSN 2225-1154, Vol. 3, no 1, p. 118-132Article in journal (Refereed) Published
Abstract [en]

Lack of suitable observational data makes bias correction of high space and time resolution regional climate models (RCM) problematic. We present a method to construct pseudo-observational precipitation data by merging a large scale constrained RCM reanalysis downscaling simulation with coarse time and space resolution observations. The large scale constraint synchronizes the inner domain solution to the driving reanalysis model, such that the simulated weather is similar to observations on a monthly time scale. Monthly biases for each single month are corrected to the corresponding month of the observational data, and applied to the finer temporal resolution of the RCM. A low-pass filter is applied to the correction factors to retain the small spatial scale information of the RCM. The method is applied to a 12.5 km RCM simulation and proven successful in producing a reliable pseudo-observational data set. Furthermore, the constructed data set is applied as reference in a quantile mapping bias correction, and is proven skillful in retaining small scale information of the RCM, while still correcting the large scale spatial bias. The proposed method allows bias correction of high resolution model simulations without changing the fine scale spatial features, i.e., retaining the very information required by many impact models.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-1962 (URN)10.3390/cli3010118 (DOI)000357804500001 ()
Available from: 2016-04-26 Created: 2016-03-03 Last updated: 2018-01-10Bibliographically approved
Yang, W., Gardelin, M., Olsson, J. & Bosshard, T. (2015). Multi-variable bias correction: application of forest fire risk in present and future climate in Sweden. Natural hazards and earth system sciences, 15(9), 2037-2057
Open this publication in new window or tab >>Multi-variable bias correction: application of forest fire risk in present and future climate in Sweden
2015 (English)In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 15, no 9, p. 2037-2057Article in journal (Refereed) Published
Abstract [en]

As the risk of a forest fire is largely influenced by weather, evaluating its tendency under a changing climate becomes important for management and decision making. Currently, biases in climate models make it difficult to realistically estimate the future climate and consequent impact on fire risk. A distribution-based scaling (DBS) approach was developed as a post-processing tool that intends to correct systematic biases in climate modelling outputs. In this study, we used two projections, one driven by historical reanalysis (ERA40) and one from a global climate model (ECHAM5) for future projection, both having been dynamically down-scaled by a regional climate model (RCA3). The effects of the post-processing tool on relative humidity and wind speed were studied in addition to the primary variables precipitation and temperature. Finally, the Canadian Fire Weather Index system was used to evaluate the influence of changing meteorological conditions on the moisture content in fuel layers and the fire-spread risk. The forest fire risk results using DBS are proven to better reflect risk using observations than that using raw climate outputs. For future periods, southern Sweden is likely to have a higher fire risk than today, whereas northern Sweden will have a lower risk of forest fire.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-1945 (URN)10.5194/nhess-15-2037-2015 (DOI)000363645500009 ()
Available from: 2016-04-29 Created: 2016-03-03 Last updated: 2018-01-10Bibliographically approved
Pisinaras, V., Yang, W., Bärring, L. & Gemitzi, A. (2014). Conceptualizing and assessing the effects of installation and operation of photovoltaic power plants on major hydrologic budget constituents. Science of the Total Environment, 493, 239-250
Open this publication in new window or tab >>Conceptualizing and assessing the effects of installation and operation of photovoltaic power plants on major hydrologic budget constituents
2014 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 493, p. 239-250Article in journal (Refereed) Published
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.

Keywords
Climate change, SWAT model, Land use change, Hydrology, Photovoltaic parks
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-106 (URN)10.1016/j.scitotenv.2014.05.132 (DOI)000340312000026 ()24950497 (PubMedID)
Available from: 2015-04-14 Created: 2015-03-26 Last updated: 2017-05-10Bibliographically approved
Donnelly, C., Yang, W. & Dahne, J. (2014). River discharge to the Baltic Sea in a future climate. Climatic Change, 122(1-2), 157-170
Open this publication in new window or tab >>River discharge to the Baltic Sea in a future climate
2014 (English)In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 122, no 1-2, p. 157-170Article in journal (Refereed) Published
Abstract [en]

This study reports on new projections of discharge to the Baltic Sea given possible realisations of future climate and uncertainties regarding these projections. A high-resolution, pan-Baltic application of the Hydrological Predictions for the Environment (HYPE) model was used to make transient simulations of discharge to the Baltic Sea for a mini-ensemble of climate projections representing two high emissions scenarios. The biases in precipitation and temperature adherent to climate models were adjusted using a Distribution Based Scaling (DBS) approach. As well as the climate projection uncertainty, this study considers uncertainties in the bias-correction and hydrological modelling. While the results indicate that the cumulative discharge to the Baltic Sea for 2071 to 2100, as compared to 1971 to 2000, is likely to increase, the uncertainties quantified from the hydrological model and the bias-correction method show that even with a state-of-the-art methodology, the combined uncertainties from the climate model, bias-correction and impact model make it difficult to draw conclusions about the magnitude of change. It is therefore urged that as well as climate model and scenario uncertainty, the uncertainties in the bias-correction methodology and the impact model are also taken into account when conducting climate change impact studies.

National Category
Natural Sciences Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:smhi:diva-166 (URN)10.1007/s10584-013-0941-y (DOI)000328622900013 ()
Available from: 2015-03-31 Created: 2015-03-26 Last updated: 2018-01-11Bibliographically approved
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