The Experts below are selected from a list of 460299 Experts worldwide ranked by ideXlab platform
C. Brühl - One of the best experts on this subject based on the ideXlab platform.
-
Impact of large solar zenith angles on lower stratospheric dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs larger than 87.5º on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5º are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially at the end of polar night the conversion of Cl2 and Cl2O2 into ClO in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93º with those of the sensitivity run with SZAs confined to 87.5º total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is about 4 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to -4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of large SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring. This study clearly shows the necessity of considering large SZAs for the calculation of photolysis rates in atmospheric models.
-
Impact of high solar zenith angles on dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics Discussions, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at high solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs greater than 87.5° on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5° are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially the conversion of Cl2 and Cl2O2 into ClO at the end of polar night in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93° with those of the sensitivity run with SZAs confined to 87.5° total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is 2?3 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to ?4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of high SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring.
Richard L Smith - One of the best experts on this subject based on the ideXlab platform.
-
green Chemical Processes with supercritical fluids properties materials separations and energy
Journal of Supercritical Fluids, 2011Co-Authors: Hiroshi Machida, Masafumi Takesue, Richard L SmithAbstract:Abstract In this work, an overview of the properties of supercritical fluids is given on using water and carbon dioxide for developing green Chemical Processes. Present industrial Processes and emerging technologies that use supercritical fluids are highlighted. Supercritical fluids are being used in transcritical cycles for heat transfer due to their favorable thermophysical properties and their environmental compatibility. Supercritical water is being proposed as a reaction solvent for zinc silicate industrial phosphors, since it allows production of luminescent materials at low temperatures (400 °C) and with less energy than industrial solid-state methods that require high temperatures (1200 °C). Supercritical CO 2 –ionic liquid systems have much potential as biphasic systems for reactions and separations, however, when used for chiral separations, the selectivity of these systems is not well understood yet. The use of supercritical CO 2 for viscosity reduction in ionic liquid reaction systems seems to be a favorable research area with conversion of d -fructose to 5-hydroxymethylfurfural in high yields (>90%) being an example. Systems to convert biomass to energy by direct oxidation in supercritical water are under development. Many opportunities exist for developing green Chemical Processes with supercritical fluids.
-
decentralized Chemical Processes with supercritical fluid technology for sustainable society
Journal of Supercritical Fluids, 2009Co-Authors: Kunio Arai, Richard L Smith, Taku M. AidaAbstract:For sustainable society, the design philosophy of Chemical Processes will need to be changed from large-scale mass production systems to decentralized local-scale production systems so that Chemicals and energies can be supplied from diverse biomass and other renewable resources. Supercritical water allows fast reaction rates, high selectivities and high-yield conversions of many biomass and biomass-related feedstocks and allows Chemical transformations to occur with compact devices. Supercritical carbon dioxide allows selective separations, efficient transformations, and low-energy processing of many types of materials. In this overview, sustainability is examined with respect to available solar energy, UN Millennium Development Goals, the carbon cycle and competing factors that affect sustainable society. Through a general block diagram for a biomass refinery, material conversions of biomass and biomass-related compounds are discussed along with a proposal for using supercritical water oxidation (SCWO) with biomass boiler to produce energy and a biorefinery on a 100 ha land area. Supercritical fluid technology, especially water and carbon dioxide solvents, can provide the basis for decentralizing Chemical Processes and for achieving material recycles for sustainable society.
D. Lamago - One of the best experts on this subject based on the ideXlab platform.
-
Impact of large solar zenith angles on lower stratospheric dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs larger than 87.5º on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5º are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially at the end of polar night the conversion of Cl2 and Cl2O2 into ClO in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93º with those of the sensitivity run with SZAs confined to 87.5º total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is about 4 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to -4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of large SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring. This study clearly shows the necessity of considering large SZAs for the calculation of photolysis rates in atmospheric models.
-
Impact of high solar zenith angles on dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics Discussions, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at high solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs greater than 87.5° on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5° are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially the conversion of Cl2 and Cl2O2 into ClO at the end of polar night in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93° with those of the sensitivity run with SZAs confined to 87.5° total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is 2?3 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to ?4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of high SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring.
V. Eyring - One of the best experts on this subject based on the ideXlab platform.
-
Impact of large solar zenith angles on lower stratospheric dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs larger than 87.5º on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5º are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially at the end of polar night the conversion of Cl2 and Cl2O2 into ClO in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93º with those of the sensitivity run with SZAs confined to 87.5º total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is about 4 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to -4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of large SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring. This study clearly shows the necessity of considering large SZAs for the calculation of photolysis rates in atmospheric models.
-
Impact of high solar zenith angles on dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics Discussions, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at high solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs greater than 87.5° on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5° are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially the conversion of Cl2 and Cl2O2 into ClO at the end of polar night in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93° with those of the sensitivity run with SZAs confined to 87.5° total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is 2?3 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to ?4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of high SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring.
C. Schnadt - One of the best experts on this subject based on the ideXlab platform.
-
Impact of large solar zenith angles on lower stratospheric dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs larger than 87.5º on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5º are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially at the end of polar night the conversion of Cl2 and Cl2O2 into ClO in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93º with those of the sensitivity run with SZAs confined to 87.5º total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is about 4 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to -4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of large SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring. This study clearly shows the necessity of considering large SZAs for the calculation of photolysis rates in atmospheric models.
-
Impact of high solar zenith angles on dynamical and Chemical Processes in a coupled chemistry-climate model
Atmospheric Chemistry and Physics Discussions, 2003Co-Authors: D. Lamago, M. Dameris, C. Schnadt, V. Eyring, C. BrühlAbstract:Actinic fluxes at high solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs greater than 87.5° on dynamical and Chemical Processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5° are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially the conversion of Cl2 and Cl2O2 into ClO at the end of polar night in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93° with those of the sensitivity run with SZAs confined to 87.5° total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is 2?3 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to ?4 K with obvious consequences for Chemical Processes. In the Northern Hemisphere the impact of high SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring.