Lifetimes, scavenging ratios, andbudgets describe the cycling of atmosphericconstituents and are ... more Lifetimes, scavenging ratios, andbudgets describe the cycling of atmosphericconstituents and are often used in formulating airpollution control strategies. Most previous studiesof sulfur lifetimes, budgets, and scavenging ratioshave been based on limited observational data or datafrom highly simplified models. The Regional AcidDeposition Model (RADM2.61) shows some skill inpredicting atmospheric mixing ratios of acidicmaterials and other related trace constituents andacid deposition patterns in North America, and so,analysis of its established, theoretical, databaseserves as a counterpoint to previous studies of sulfurbudgets, lifetimes, and scavenging ratios. The annualbudget shows that the net transport (outflow minusinflow) of sulfur compounds out of eastern NorthAmerica is equal to the total deposition within thedomain. Of the total deposition, 63% is from wetdeposition and 37% is from dry deposition. Theannual average lifetime of sulfur dioxide (38 hours),estimated by the turnover time, is limited by aqueousconversion, while that for sulfate aerosols (54 hours)is limited by their removal in precipitation. Theannual average lifetime of sulfur in this domain isslightly more than three days. Episodic lifetimes andbudgets, based on particular synoptic situations, showlarge variations around the annual values. Episodicprecipitation scavenging ratios exhibit similarvariability and are used to offer explanations ofseveral potential biases found in the wet sulfurdeposition amounts as predicted by the EMEP sulfurtransport model and other published results.
... and Saffet Tanrikulu and John DaMassa Technical Support Division Air Resources Board Californ... more ... and Saffet Tanrikulu and John DaMassa Technical Support Division Air Resources Board California Environmental Protection Agency 2020 L Street Sacramento, Califomia 95814 ... range from sea level to more than 3200 m at the summit of the Siem Nevada mountain range. ...
The performance of numerical techniques in solving differential equations of the gas phase chemis... more The performance of numerical techniques in solving differential equations of the gas phase chemistry submodel (i.e., the chemical solver) is one of the most important factors in determining the overall computational cost for a three-dimensional (3-D) Air Quality Model (AQM). The estimated performance of a chemical solver in an AQM is often obtained by using simple box model analysis. In the present work some essential characteristics of the computational environment of any AQM, the operator splitting technique, have been identified and shown that different evaluation procedures will result in different conclusions for the relative performances of chemical solvers. A new box model evaluation procedure incorporating the impact of operator splitting has been designed to better mimic the true performances of various chemical solvers. Among the chemical solvers tested, the Hertel solver has the best overall performance and is the most robust in dealing with diverse computational environments.
... Julius S. Chang. Lawrence Livermore Laboratory, University of California, Livermore, CA 94550... more ... Julius S. Chang. Lawrence Livermore Laboratory, University of California, Livermore, CA 94550. Changes in ozone, temperature, and other minor constituents resulting from eleven‐year variations in the solar flux between 180 and 340 nm are presented. ...
It has been suggested (Hudson,(1977)) that monitoring Oâ levels in the upper stratosphere may pro... more It has been suggested (Hudson,(1977)) that monitoring Oâ levels in the upper stratosphere may provide an early warning signal for detection of changes in ozone owing to the effects of increasing chlorine burden. Penner and Chang (1978) suggested that the possible influence of changing solar UV flux may hinder this effort. Their study is extended here to investigate whether measurement of other trace species may yield more definitive information. Present study suggests that the long-term trend in upper stratospheric NâO may provide more suitable data, though indirect, on the supposed solar UV variations, hence better quantification of one potential mechanism of long-term natural variations in ozone.
Lifetimes, scavenging ratios, andbudgets describe the cycling of atmosphericconstituents and are ... more Lifetimes, scavenging ratios, andbudgets describe the cycling of atmosphericconstituents and are often used in formulating airpollution control strategies. Most previous studiesof sulfur lifetimes, budgets, and scavenging ratioshave been based on limited observational data or datafrom highly simplified models. The Regional AcidDeposition Model (RADM2.61) shows some skill inpredicting atmospheric mixing ratios of acidicmaterials and other related trace constituents andacid deposition patterns in North America, and so,analysis of its established, theoretical, databaseserves as a counterpoint to previous studies of sulfurbudgets, lifetimes, and scavenging ratios. The annualbudget shows that the net transport (outflow minusinflow) of sulfur compounds out of eastern NorthAmerica is equal to the total deposition within thedomain. Of the total deposition, 63% is from wetdeposition and 37% is from dry deposition. Theannual average lifetime of sulfur dioxide (38 hours),estimated by the turnover time, is limited by aqueousconversion, while that for sulfate aerosols (54 hours)is limited by their removal in precipitation. Theannual average lifetime of sulfur in this domain isslightly more than three days. Episodic lifetimes andbudgets, based on particular synoptic situations, showlarge variations around the annual values. Episodicprecipitation scavenging ratios exhibit similarvariability and are used to offer explanations ofseveral potential biases found in the wet sulfurdeposition amounts as predicted by the EMEP sulfurtransport model and other published results.
... and Saffet Tanrikulu and John DaMassa Technical Support Division Air Resources Board Californ... more ... and Saffet Tanrikulu and John DaMassa Technical Support Division Air Resources Board California Environmental Protection Agency 2020 L Street Sacramento, Califomia 95814 ... range from sea level to more than 3200 m at the summit of the Siem Nevada mountain range. ...
The performance of numerical techniques in solving differential equations of the gas phase chemis... more The performance of numerical techniques in solving differential equations of the gas phase chemistry submodel (i.e., the chemical solver) is one of the most important factors in determining the overall computational cost for a three-dimensional (3-D) Air Quality Model (AQM). The estimated performance of a chemical solver in an AQM is often obtained by using simple box model analysis. In the present work some essential characteristics of the computational environment of any AQM, the operator splitting technique, have been identified and shown that different evaluation procedures will result in different conclusions for the relative performances of chemical solvers. A new box model evaluation procedure incorporating the impact of operator splitting has been designed to better mimic the true performances of various chemical solvers. Among the chemical solvers tested, the Hertel solver has the best overall performance and is the most robust in dealing with diverse computational environments.
... Julius S. Chang. Lawrence Livermore Laboratory, University of California, Livermore, CA 94550... more ... Julius S. Chang. Lawrence Livermore Laboratory, University of California, Livermore, CA 94550. Changes in ozone, temperature, and other minor constituents resulting from eleven‐year variations in the solar flux between 180 and 340 nm are presented. ...
It has been suggested (Hudson,(1977)) that monitoring Oâ levels in the upper stratosphere may pro... more It has been suggested (Hudson,(1977)) that monitoring Oâ levels in the upper stratosphere may provide an early warning signal for detection of changes in ozone owing to the effects of increasing chlorine burden. Penner and Chang (1978) suggested that the possible influence of changing solar UV flux may hinder this effort. Their study is extended here to investigate whether measurement of other trace species may yield more definitive information. Present study suggests that the long-term trend in upper stratospheric NâO may provide more suitable data, though indirect, on the supposed solar UV variations, hence better quantification of one potential mechanism of long-term natural variations in ozone.
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