| 1. |
- Abou Rafee, Sameh Adib, et al.
(författare)
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Hydrologic response to large-scale land use and cover changes in the Upper Paraná River Basin between 1985 and 2015
- 2021
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Ingår i: Regional Environmental Change. - : Springer Science and Business Media LLC. - 1436-3798 .- 1436-378X. ; 21:4
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Tidskriftsartikel (refereegranskat)abstract
- The Upper Paraná River Basin (UPRB) has undergone remarkable land use and cover changes (LUCC) in recent decades. This paper analyses the hydrologic response to LUCC in the UPRB between 1985 and 2015, using the Soil and Water Assessment Tool (SWAT) model. The impacts of LUCC were examined for annual, wet, and dry season (both during calibrated and validated periods) between 1984 and 2015. The most substantial LUCC were the extensive reduction of the cerrado and the expansion of agriculture areas. The simulations demonstrated that the LUCC caused important changes in basin hydrology. For instance, an increase (decrease) of surface runoff in the wet (dry) season at most UPRB subbasins was observed. In addition, the simulation results revealed a reduction in actual evapotranspiration and an increase in soil moisture in the annual and wet season. Consequently, most of the major rivers of the basin presented an increase (decrease) in their discharge in the wet (dry) period. The major changes in the hydrologic components were observed in the central-western and southern parts of the UPRB. At the river mouth of the UPRB, the LUCC led to an increase in long-term mean discharge values of 4.2% and 1.1% in the annual and wet season and a decrease of about 2.2% in the dry period. This study provides a large-scale modeling and valuable information that could be used to improve planning and sustainable management of future water resources within the basin.
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| 2. |
- Ahlström, Anders, et al.
(författare)
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GCM characteristics explain the majority of uncertainty in projected 21st century terrestrial ecosystem carbon balance
- 2012
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Ingår i: Biogeosciences Discussions. - : Copernicus GmbH. - 1810-6277. ; 9, s. 13685-13712
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- One of the largest sources of uncertainties in modelling of the future global climate is the response of the terrestrial carbon cycle. Studies have shown that it is likely that the extant land sink of carbon will weaken in a warming climate. Should this happen, a larger portion of the annual carbon dioxide emissions will remain in the atmosphere, and further increase global warming, which in turn may further weaken the land sink. We investigate the potential sensitivity of global terrestrial ecosystem carbon balance to differences in future climate simulated by four general circulation models (GCMs) under three different CO2 concentration scenarios. We find that the response in simulated carbon balance is more influenced by GCMs than CO2 concentration scenarios. Empirical orthogonal function (EOF) analysis of sea surface temperatures (SSTs) reveals differences among GCMs in simulated SST variability leading to decreased tropical ecosystem productivity in two out of four GCMs. We extract parameters describing GCM characteristics by parameterizing a statistical emulator mimicking the carbon balance response simulated by a full dynamic ecosystem model. By sampling two GCM-specific parameters and global temperatures we create 60 new "artificial" GCMs and investigate the extent to which the GCM characteristics may explain the uncertainty in global carbon balance under future radiative forcing. Differences among GCMs in the representation of SST variability and ENSO and its effect on precipitation and temperature patterns explain the majority of the uncertainty in the future evolution of global terrestrial ecosystem carbon in our analysis. We suggest that the characterisation and evaluation of patterns and trends in simulated SST variability should be a priority for the further development of GCMs, in particular as vegetation dynamics and carbon cycle feedbacks are incorporated.
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| 3. |
- Ahlström, Anders, et al.
(författare)
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GCM characteristics explain the majority of uncertainty in projected 21st century terrestrial ecosystem carbon balance
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 10:3, s. 1517-1528
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Tidskriftsartikel (refereegranskat)abstract
- One of the largest sources of uncertainties in modelling of the future global climate is the response of the terrestrial carbon cycle. Studies have shown that it is likely that the extant land sink of carbon will weaken in a warming climate. Should this happen, a larger portion of the annual carbon dioxide emissions will remain in the atmosphere, and further increase global warming, which in turn may further weaken the land sink. We investigate the potential sensitivity of global terrestrial ecosystem carbon balance to differences in future climate simulated by four general circulation models (GCMs) under three different CO2 concentration scenarios. We find that the response in simulated carbon balance is more influenced by GCMs than CO2 concentration scenarios. Empirical orthogonal function (EOF) analysis of sea surface temperatures (SSTs) reveals differences among GCMs in simulated SST variability leading to decreased tropical ecosystem productivity in two out of four GCMs. We extract parameters describing GCM characteristics by parameterizing a statistical emulator mimicking the carbon balance response simulated by a full dynamic ecosystem model. By sampling two GCM-specific parameters and global temperatures we create 60 new "artificial" GCMs and investigate the extent to which the GCM characteristics may explain the uncertainty in global carbon balance under future radiative forcing. Differences among GCMs in the representation of SST variability and ENSO and its effect on precipitation and temperature patterns explain the majority of the uncertainty in the future evolution of global terrestrial ecosystem carbon in our analysis. We suggest that the characterisation and evaluation of patterns and trends in simulated SST variability should be a priority for the further development of GCMs, in particular as vegetation dynamics and carbon cycle feedbacks are incorporated.
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| 4. |
- Ali Maher, Osama, et al.
(författare)
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Comparison between two extreme NAO winters and consequences on the thermal regime of Lake Vendyurskoe, Karelia
- 2005
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Ingår i: Journal of Hydrometeorology. - 1525-755X. ; 6:5, s. 775-783
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Tidskriftsartikel (refereegranskat)abstract
- For 10 consecutive winters, measurements were carried out in Lake Vendyurskoe, Karelia, Russia. The aim of these measurements was to investigate some of the physical processes in this small shallow lake during its ice-covered period. Detailed measurements of ice thickness and condition, snow thickness, water temperature, salt content, and currents were developed into a database. Within this database are the winters 1994/95 and 1995/96, which are characterized by a very sharp change between positive and negative phases of the North Atlantic Oscillation (NAO). This note investigates and compares the effects of these two NAO phases on the regional climate and their relation to the thermal regime of Lake Vendyurskoe. It became clear that the ice-covered period length did not vary much from one winter to the other; however, a large difference was observed in the maximum average ice cover thickness and in the average water temperature at ice formation ( e. g., larger thickness and colder water temperature during the 1995/ 96 winter).
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| 5. |
- Berndtsson, Ronny, et al.
(författare)
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Hydrology for Environmental Engineers
- 2014
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This textbook aims to provide a comprehensible introduction to Engineering Hydrology for environmental engineering students. The book comprises of 8 chapters which provide a holistic view of hydrology, seen as the water transport in nature with human influence, and deal with the main hydrological systems and processes. Each chapter ends with a few engineering examples together with a discussion of calculation methods, followed by further engineering problems. The book has been compiled from earlier hydrology textbooks from the Department of Water Resources Engineering at LTH, Lund University, Sweden. The most important contributions are from Lars Anderberg (“Kort introduktion till hydrologi”) and Rolf Larsson (“Övningsexempelsamling avsett för Väg&vatten-byggnadsingenjörer vid LTH”).
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| 6. |
- Berndtsson, Ronny, et al.
(författare)
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Riseberga Restoration Project
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This project is designed as a typical consultancy work for Environmental Engineering students at the Faculty of Engineering (LTH), Lund University, Sweden. It gives students a feeling of a possible future work by being a practical training in solving a complex environmental problem involving hydrological and ecological challenges. Additionally, the project work provides training of critical thinking, engineering techniques and presentation of technical reports. The outcome of this work is a proposal for restoration of a wetland at Riseberga River Basin in Malmö, southern Sweden. It will be presented as a report as well as an oral presentation of the restoration plan at the end of the semester by each group.
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| 7. |
- Bertacchi Uvo, Cintia
(författare)
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Analysis and regionalization of northern european winter precipitation based on its relationship with the North Atlantic oscillation
- 2003
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Ingår i: International Journal of Climatology. - : Wiley. - 1097-0088 .- 0899-8418. ; 23:10, s. 1185-1194
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between the North Atlantic oscillation (NAO) and winter temperature and precipitation over northern Europe has long been known. However, its strength is variable within this region. In this paper, an analysis of the regional variability of the influence of the NAO on winter precipitation in northern Europe is developed using empirical orthogonal function analysis, cluster analysis and simple correlation. Results show that precipitation in most of the region studied is affected by the NAO, although with varying intensity. The NAO strongly influences winter precipitation along the Norwegian coast, in northern Sweden and in southern Finland. It is evident that the region on the lee side of the Scandes (the mountain chain between Norway and Sweden) is protected from the effects of the moist western winds from the Atlantic that, in turn, are strongly related to the NAO. As a result, precipitation in this shielded area is mainly related to southeasterly winds. Copyright (C) 2003 Royal Meteorological Society.
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| 8. |
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| 9. |
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| 10. |
- Bertacchi Uvo, Cintia
(författare)
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Influence of Sea Surface Temperature on Rainfall and Runof in Northeastern South America: Analysis and Modeling
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work represents an amalgam of a group of studies with the purpose of understanding the influence of the Pacific and Atlantic sea surface temperature on precipitation and river discharge in Northeastern South America. Sea surface temperature is a good representative of phenomena such as ENSO that, in turn, cause worldwide climate variability. The patterns of the Atlantic Ocean sea surface temperature anomaly also plays a very important role in the precipitation over the neighboring regions and a special investigation was also carried out to better understanding this influence. The influence of these oceans' sea surface temperature on the intraseasonal variability of precipitation in Northeast Brazil was also a particular subject of study. Statistical methods were largely used both during these investigations and in the development of models for forecasting discharge long term in advance at some sites in the Amazon, Orinoco and Tocantins River Basins. Sea surface temperature anomalies in both oceans significantly influence precipitation over northeastern South America. The Atlantic Ocean, however, plays a more important role in the case of precipitation over Northeast Brazil while the Pacific Ocean seems to have stronger influence over eastern and northern Amazonia. As a result of changes in precipitation, the river discharge in the Amazon Region is also influenced by changes in sea surface temperature patterns. The discharge of rivers located to the north of the Amazon River is mainly influenced by the Pacific sea surface temperature while the Atlantic influences the rivers to the south of the Amazon River. This influence could be clearly observed using the forecast models. Two different methodologies were used to develop forecast models: Canonical Correlation Analysis and Artificial Neural Network. The first is a linear technique and the second a non-linear one. In both cases, the models developed using Pacific sea surface temperature were better at forecasting discharge at sites to the north of the Amazon River and those developed from Atlantic sea surface temperature at forecasting discharges at sites to the south of the Amazon River. Even though the use of a non-linear technique improved the accuracy of the models in general, it considerably improved the capacity of Atlantic sea surface temperature to forecast discharge. This general improvement was to some degree expected considering the very complex and non-linear mechanisms that transform precipitation into discharge.
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