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Global and European climate response to transient forcings since 1870, as simulated in an atmospheric general circulation model
Bichet Adeline - ETH, 2012Predicting and adapting to climate change is one of the major challenges for the twenty-first century. To better understand the future changes in precipitation associated with climate change on the global and regional scale, this thesis investigates, for the past 140 years, the time-varying impact of the major climate forcings on precipitation. To do so, the global climate is simulated between 1870 and 2005 in a transient mode with the atmospheric general circulation model “ECHAM5- HAM”. The model is forced with observationally based time-varying sea surface temperatures (SSTs) and the major ...
Global and European climate response to transient forcings since 1870, as simulated in an atmospheric general circulation model
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Available online: http://e-collection.library.ethz.ch/eserv/eth:5845/eth-5845-02.pdf
Published by: ETH ; 2012
Predicting and adapting to climate change is one of the major challenges for the twenty-first century. To better understand the future changes in precipitation associated with climate change on the global and regional scale, this thesis investigates, for the past 140 years, the time-varying impact of the major climate forcings on precipitation. To do so, the global climate is simulated between 1870 and 2005 in a transient mode with the atmospheric general circulation model “ECHAM5- HAM”. The model is forced with observationally based time-varying sea surface temperatures (SSTs) and the major climate forcings, which include total solar irradiance, volcanic optical depth, aerosol emissions (natural and anthropogenic), and greenhouse gas concentrations. Sensitivity experiments, holding one or more of these forcings constant throughout the experiments are then used to identify and quantify their time-varying impacts on the hydrological cycle. In a first step, the thesis aims to identify the main climate forcings driving the decadal variability of global land temperature and precipitation between 1870 and 2005. It then investigates the causes driving the wind stilling observed over land after 1970 in many sites over the globe, due to its potential impact on the hydrological cycle and on industries such as wind powered energy. Finally, the high precipitation anomalies observed in central Europe in the late nineteenth century are also investigated, for their potential contribution to the accumulation of destructive floods recorded at the time in central Europe.
Language(s): English
Format: Digital (Free), Hard copyTags: Climate ; Climate prediction ; Atmospheric circulation ; Atmospheric model ; Region VI - Europe
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Modelling ocean Acidification in the California Current System : a dissertation submitted to ETH Zurich
Eastern boundary upwelling systems (EBUS) are naturally more acidic than most of the rest of the surface ocean. Observations of EBUS already show pH values and saturation states with regard to the carbonate mineral aragonite that are as low as those expected for most open ocean waters several decades from now. Thus, as atmospheric CO2 increases further, EBUS are prone to widespread and persistent undersaturation with regard to aragonite, making them especially sensitive to ocean acidification. Here, we describe ocean carbonate chemistry and its short-term-to-seasonal variability in one major E ...
Modelling ocean Acidification in the California Current System: a dissertation submitted to ETH Zurich
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Available online: http://dx.doi.org/10.5670/oceanog.2009.97
Published by: ETH ; 2012
Eastern boundary upwelling systems (EBUS) are naturally more acidic than most of the rest of the surface ocean. Observations of EBUS already show pH values and saturation states with regard to the carbonate mineral aragonite that are as low as those expected for most open ocean waters several decades from now. Thus, as atmospheric CO2 increases further, EBUS are prone to widespread and persistent undersaturation with regard to aragonite, making them especially sensitive to ocean acidification. Here, we describe ocean carbonate chemistry and its short-term-to-seasonal variability in one major EBUS, the California Current System (CCS), based on observations and results from an eddy-resolving regional model. Results reveal high variability in ocean carbonate chemistry, largely driven by seasonal upwelling of waters with low pH and saturation states, and subsequent interactions of transport and biological production. Model simulations confirm that the pH of CCS waters has decreased by about 0.1 pH unit and by 0.5 in saturation state since pre-industrial times. A first assessment of the vulnerability of CCS marine organisms and ecosystems to ocean acidification suggests that there will be winners and losers, likely provoking changes in species composition. Benthic organisms appear to be among those that will be most affected by the continuing acidification of the CCS. More accurate projections require special consideration of the integrated effects of ocean acidification, ocean warming, decreasing oxygen levels, and other processes that are expected with global change.
Language(s): English
Format: Digital (Free), Hard copyTags: Oceans ; Oceans acidification ; Ocean model
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