Joseph M . Steed - Academia.edu (original) (raw)
Papers by Joseph M . Steed
The Astrophysical Journal, 1979
Five laboratory radio-frequency transitions observed for the dimer of carbon monoxide are reporte... more Five laboratory radio-frequency transitions observed for the dimer of carbon monoxide are reported. The species (CO)2 appears to be nonrigid. No emission was detected in a search of 11 interstellar sources at 1.458 GHz. It is estimated that the ratio (CO)2/CO is less than 1% in these sources.
Advances in Nuclear Science & Technology, 1980
Hazard Assessment of Chemicals, 1984
Atmospheric Environment (1967), 1986
In order to understand the present concentration distribution of CCl,F and CC12FI in the atmosphe... more In order to understand the present concentration distribution of CCl,F and CC12FI in the atmosphere and their atmospheric lifetimes, accurate data on the global production and release of these materials are needed. This papezr reports improvements in the understanding of certain production and use categories which increase the accuracy of the estimates of these releases. However, lack of recent production data from certain sources prevents the total world production, and hence release, estimates from reflecting similar accuracy.
The two-dimensional model described by Miller et al. (1980) has been used to calculate vertical m... more The two-dimensional model described by Miller et al. (1980) has been used to calculate vertical mixing ratio profiles for the atmospheric chlorine species HCl and ClO. Briefly, the model includes 30 chemical species. The chemistry is treated as completely as that in advanced 1-D models. Attention is given to the degree to which a comparison of 2-D results for 30 deg N with measurements at the same latitude is similar to that for 1-D calculations. It is found that the profiles considered are qualitatively and quantitatively similar to 1-D results as a band representing the range of seasonal HCl profiles over the year 1976 is plotted along with a compilation of spectroscopic HCl measurements made by various investigators. Qualitative differences in profile shapes between models and measurements indicate likely errors in partitioning and are probably related to chemistry rather than other uncertainties.
A description is presented of the structural features of a two-dimensional model of atmospheric t... more A description is presented of the structural features of a two-dimensional model of atmospheric transport and photochemistry. The model has been designed to include a chemical scheme comparable with that in advanced one-dimensional models, and to transport each species individually, rather than invoking family grouping approximations. Considerable flexibility has been provided for modifying the vertical and latitudinal grid resolutions with relative ease. It is pointed out that the parameterization of the mean meridional circulation represents the first attempt in a complete 2-D chemical model to simulate directly the effects of the Lagrangian mean circulation. The chemical scheme includes 30 active species.
Nature, 1980
ABSTRACT A two-dimensional atmospheric model has been developed to take into account latitudinal ... more ABSTRACT A two-dimensional atmospheric model has been developed to take into account latitudinal and seasonal effects in the calculation of atmospheric constituent profiles. The model includes 30 active chemical species and all chemical reactions and reactions rates applicable to them for the domain from pole to pole and 0 to 55 km height; mean meridional circulation is parameterized using the advective circulation field of Murgatroyd and Singleton (1961), while eddy diffusion parameterization is basically that of Luther (1974) and spatial derivatives for transport are approximated by a second-order finite difference representation. Time-dependent integration of the model results in latitudinal variations of the N2O volume mixing ratio, CFCl3, CF2Cl2 and CH4, column ozone and HNO3 in agreement with available measurements, whereas the agreement between calculated and measured HCl and ClO profiles is found to be no better than that obtained with one-dimensional models.
![Research paper thumbnail of Erratum: Determination of the structure of ArCO2 by radiofrequency and microwave spectroscopy [J. Chem. Phys. 7 0, 4095 (1979)]](https://attachments.academia-assets.com/115339027/thumbnails/1.jpg)
](The Journal of Chemical Physics, 1981
Due to an error in programing, the weak bending force constant kb and frequency Wb for the comple... more Due to an error in programing, the weak bending force constant kb and frequency Wb for the complex were calculated incorrectly. The correct values are kb = 0.01649 mdyn/ A and <I1b= 38. 9 em-I.
International Journal of Thermophysics, 1989
The paper deals with the expected impact of the safety and environmental issues concerning the us... more The paper deals with the expected impact of the safety and environmental issues concerning the use of chlorofluorocarbons and presents a status report on alternative compounds under development.
Journal of Geophysical Research: Atmospheres, 1985
An atmosphere model composed of a narrow band radiative‐convective (RC) code coupled with a one‐d... more An atmosphere model composed of a narrow band radiative‐convective (RC) code coupled with a one‐dimensional chemistry and transport code is described. The RC model, formulated in log‐pressure coordinates, includes accurate solar absorption calculations for O3, O2, H2O, and CO2. Infrared heating and cooling by CO2, O3, and H2O are calculated with a narrow band formulation, while broader band formulations are used for CH4, N2O, CFC 11, and CFC 12. The atmospheric chemistry and transport model uses photochemical reaction rate data from Jet Propulsion Laboratory publication 82–57. The calculated steady state atmospheric response to several potential perturbations is discussed. Doubling the atmospheric CO2 level yields a change in total ozone of +2.9% and a surface temperature increase of 1.7 K. The continued release of chlorofluorocarbons (CFC's) alone at nominal rates gives a calculated column ozone change of −5.7% at steady state, while for a combined 2×CO2+CFC perturbation the re...
Journal of Geophysical Research: Oceans, 1981
A two‐dimensional chemical model of the atmosphere is described. The model includes the major fea... more A two‐dimensional chemical model of the atmosphere is described. The model includes the major features associated with advanced one‐dimensional models: 30 active chemical species and all the important chemical reactions connecting them, diurnal effects, and Rayleigh scattering. The species are transported and calculated separately, with the exception of the odd oxygen family [O3, O(3P), O(1D)] and H and N atoms. The transport scheme contains both diffusive and advective terms, with the advective circulation field of Murgatroyd and Singleton (appropriately scaled) used to approximate the Lagrangian mean flow. Comparison of the model predictions with atmospheric observations of long‐lived trace species such as O3, N2O, CF2Cl2, CFCl3, and CH4 suggests that the transport parameterization gives a good representation of actual trace species motions. For constituents which are more active or whose chemistry is less well known, the model is a useful diagnostic tool for assessing our current...
Geophysical Research Letters, 1982
Using a one dimensional atmospheric Miller et al. (1981) and the references found model, we inves... more Using a one dimensional atmospheric Miller et al. (1981) and the references found model, we investigate the possible influence of an therein. For these calculations, 30 chemical increase in atmospheric methane on ozone. The species were active, including all those currently couplings between methane and the catalytic identified as important to methane and ozone destruction of ozone by NO., HOx, and C1X are chemistry in the troposphere and stratosphere. discussed. Our model calculations suggest that Recent updates to the model include the addition doubling the ground-level flux of methane, with of clouds in the troposphere (50% cloud cover at 6 fixed atmospheric temperatures and currently km altitude) and the calculation of UV penetration recommended chemical reaction rates, would in the Schumann-Runge bands of molecular oxygen increase the total ozone column by 3.5%. based on the formulation of Frederick and Hudson Calculations showing the very significant (1980). The chemical reaction rates and incident moderating effects of a methane increase on ozone solar fluxes are those recommended by recent NASA perturbations due to N20 and chlorofluorocarbons panels (WMO, 1982). are discussed. The "initial" atmosphere used as a basis for comparison is one with no chlorofluorocarbons through a "greenhouse effect" similar to that of tropospheric methane mixing ratio were to increase CO 2 (Wang et al., 1980). Such atmospheric at a rate of 1-2% per year, as recent measurements temperature changes, which we will not discuss suggest, this source strength would be reached in here, can also perturb stratospheric chemistry. 50-100 years. The methane concentration in the 2 x CH• atmosphere is a factor of 2.8 larger than the The Impact of Increased Methane on Atmospheric initial case at the ground and 2.2 in the upper Chemistry stratosphere. The one-dimensional atmospheric chemistry and The atmospheric chemistry of methane is transport model used here has been described in complex, particularly in the troposphere (see, eg., Ehhalt and Schmidt, 1978, Logan et al., 1981). A one-dimensional model cannot properly Copyright 1982 by the American Geophysical Union. simulate the latitudinal variations of species Paper number 2Ll122. like CO, NO, and OH that are important in 0094-8276/82/002L-112253.O0 tropospheric chemistry (Logan et al., 1981).
Geophysical Research Letters, 1982
A two-dimensional (2-D) chemical significantly affect conclusions regarding their model of the at... more A two-dimensional (2-D) chemical significantly affect conclusions regarding their model of the atmosphere is used to investigate lifetimes. However, calculated rates of removal the stratospheric removal rates of the for these molecules are strongly dependent on the chlorofluorocarbons CFC 11 (CFCI•) and CFC 12 transport description in the models since (CF2CI?). Assuming equivalent vertical transport photolysis can occur only after the CFCs reach rates,-one-dimensional (I-D) models are shown to altitudes with sufficient photon flux. overestimate the atmospheric lifetime of CFC 11 The transport descriptions in atmospheric by 410% because of their neglect of latitudinal models vary widely. One approach to choosing effects. The present Du Pont 1-D and 2-D models transport parameters is to fit experimental and have somewhat different effective transport rates theoretical concentration profiles for long-lived and give steady state CFC 11 atmospheric trace species like N20 (with a ground-level lifetimes of 75 and 60 years, respectively, •source) and ozone (with a stratospheric source). assuming no tropospheric destruction mechanism. •igure 1 compares the calculated vertical For CFC 12, the corresponding calculated profiles for N•O and O? obtained in the present lifetimes are 140 and 120 years. 1-D model (Mil{er et a., 1981b) with the global average obtained using the 2-D model (Miller et
Atmospheric Environment (1967), 1981
An updated version of a one-dimensional chemical model is described, together with a simple appro... more An updated version of a one-dimensional chemical model is described, together with a simple approach to diurnal calculations. The model is used to investigate the possible effects on model predictions of new chemistry, such as bromine and HOC1 chemistry, to compare calculated species profiles with experiment, and to evaluate, within the present chemical scheme, the magnitude of a variety of potential perturbations to stratospheric ozone. In particular the ozone depletion calculated for steady state fluorocarbon release at 1975 levels is 18.3 '% and it is shown that this number would be halved by doubling the current ground level N,O flux.
The Astrophysical Journal, 1979
Five laboratory radio-frequency transitions observed for the dimer of carbon monoxide are reporte... more Five laboratory radio-frequency transitions observed for the dimer of carbon monoxide are reported. The species (CO)2 appears to be nonrigid. No emission was detected in a search of 11 interstellar sources at 1.458 GHz. It is estimated that the ratio (CO)2/CO is less than 1% in these sources.
Advances in Nuclear Science & Technology, 1980
Hazard Assessment of Chemicals, 1984
Atmospheric Environment (1967), 1986
In order to understand the present concentration distribution of CCl,F and CC12FI in the atmosphe... more In order to understand the present concentration distribution of CCl,F and CC12FI in the atmosphere and their atmospheric lifetimes, accurate data on the global production and release of these materials are needed. This papezr reports improvements in the understanding of certain production and use categories which increase the accuracy of the estimates of these releases. However, lack of recent production data from certain sources prevents the total world production, and hence release, estimates from reflecting similar accuracy.
The two-dimensional model described by Miller et al. (1980) has been used to calculate vertical m... more The two-dimensional model described by Miller et al. (1980) has been used to calculate vertical mixing ratio profiles for the atmospheric chlorine species HCl and ClO. Briefly, the model includes 30 chemical species. The chemistry is treated as completely as that in advanced 1-D models. Attention is given to the degree to which a comparison of 2-D results for 30 deg N with measurements at the same latitude is similar to that for 1-D calculations. It is found that the profiles considered are qualitatively and quantitatively similar to 1-D results as a band representing the range of seasonal HCl profiles over the year 1976 is plotted along with a compilation of spectroscopic HCl measurements made by various investigators. Qualitative differences in profile shapes between models and measurements indicate likely errors in partitioning and are probably related to chemistry rather than other uncertainties.
A description is presented of the structural features of a two-dimensional model of atmospheric t... more A description is presented of the structural features of a two-dimensional model of atmospheric transport and photochemistry. The model has been designed to include a chemical scheme comparable with that in advanced one-dimensional models, and to transport each species individually, rather than invoking family grouping approximations. Considerable flexibility has been provided for modifying the vertical and latitudinal grid resolutions with relative ease. It is pointed out that the parameterization of the mean meridional circulation represents the first attempt in a complete 2-D chemical model to simulate directly the effects of the Lagrangian mean circulation. The chemical scheme includes 30 active species.
Nature, 1980
ABSTRACT A two-dimensional atmospheric model has been developed to take into account latitudinal ... more ABSTRACT A two-dimensional atmospheric model has been developed to take into account latitudinal and seasonal effects in the calculation of atmospheric constituent profiles. The model includes 30 active chemical species and all chemical reactions and reactions rates applicable to them for the domain from pole to pole and 0 to 55 km height; mean meridional circulation is parameterized using the advective circulation field of Murgatroyd and Singleton (1961), while eddy diffusion parameterization is basically that of Luther (1974) and spatial derivatives for transport are approximated by a second-order finite difference representation. Time-dependent integration of the model results in latitudinal variations of the N2O volume mixing ratio, CFCl3, CF2Cl2 and CH4, column ozone and HNO3 in agreement with available measurements, whereas the agreement between calculated and measured HCl and ClO profiles is found to be no better than that obtained with one-dimensional models.
The Journal of Chemical Physics, 1981
Due to an error in programing, the weak bending force constant kb and frequency Wb for the comple... more Due to an error in programing, the weak bending force constant kb and frequency Wb for the complex were calculated incorrectly. The correct values are kb = 0.01649 mdyn/ A and <I1b= 38. 9 em-I.
International Journal of Thermophysics, 1989
The paper deals with the expected impact of the safety and environmental issues concerning the us... more The paper deals with the expected impact of the safety and environmental issues concerning the use of chlorofluorocarbons and presents a status report on alternative compounds under development.
Journal of Geophysical Research: Atmospheres, 1985
An atmosphere model composed of a narrow band radiative‐convective (RC) code coupled with a one‐d... more An atmosphere model composed of a narrow band radiative‐convective (RC) code coupled with a one‐dimensional chemistry and transport code is described. The RC model, formulated in log‐pressure coordinates, includes accurate solar absorption calculations for O3, O2, H2O, and CO2. Infrared heating and cooling by CO2, O3, and H2O are calculated with a narrow band formulation, while broader band formulations are used for CH4, N2O, CFC 11, and CFC 12. The atmospheric chemistry and transport model uses photochemical reaction rate data from Jet Propulsion Laboratory publication 82–57. The calculated steady state atmospheric response to several potential perturbations is discussed. Doubling the atmospheric CO2 level yields a change in total ozone of +2.9% and a surface temperature increase of 1.7 K. The continued release of chlorofluorocarbons (CFC's) alone at nominal rates gives a calculated column ozone change of −5.7% at steady state, while for a combined 2×CO2+CFC perturbation the re...
Journal of Geophysical Research: Oceans, 1981
A two‐dimensional chemical model of the atmosphere is described. The model includes the major fea... more A two‐dimensional chemical model of the atmosphere is described. The model includes the major features associated with advanced one‐dimensional models: 30 active chemical species and all the important chemical reactions connecting them, diurnal effects, and Rayleigh scattering. The species are transported and calculated separately, with the exception of the odd oxygen family [O3, O(3P), O(1D)] and H and N atoms. The transport scheme contains both diffusive and advective terms, with the advective circulation field of Murgatroyd and Singleton (appropriately scaled) used to approximate the Lagrangian mean flow. Comparison of the model predictions with atmospheric observations of long‐lived trace species such as O3, N2O, CF2Cl2, CFCl3, and CH4 suggests that the transport parameterization gives a good representation of actual trace species motions. For constituents which are more active or whose chemistry is less well known, the model is a useful diagnostic tool for assessing our current...
Geophysical Research Letters, 1982
Using a one dimensional atmospheric Miller et al. (1981) and the references found model, we inves... more Using a one dimensional atmospheric Miller et al. (1981) and the references found model, we investigate the possible influence of an therein. For these calculations, 30 chemical increase in atmospheric methane on ozone. The species were active, including all those currently couplings between methane and the catalytic identified as important to methane and ozone destruction of ozone by NO., HOx, and C1X are chemistry in the troposphere and stratosphere. discussed. Our model calculations suggest that Recent updates to the model include the addition doubling the ground-level flux of methane, with of clouds in the troposphere (50% cloud cover at 6 fixed atmospheric temperatures and currently km altitude) and the calculation of UV penetration recommended chemical reaction rates, would in the Schumann-Runge bands of molecular oxygen increase the total ozone column by 3.5%. based on the formulation of Frederick and Hudson Calculations showing the very significant (1980). The chemical reaction rates and incident moderating effects of a methane increase on ozone solar fluxes are those recommended by recent NASA perturbations due to N20 and chlorofluorocarbons panels (WMO, 1982). are discussed. The "initial" atmosphere used as a basis for comparison is one with no chlorofluorocarbons through a "greenhouse effect" similar to that of tropospheric methane mixing ratio were to increase CO 2 (Wang et al., 1980). Such atmospheric at a rate of 1-2% per year, as recent measurements temperature changes, which we will not discuss suggest, this source strength would be reached in here, can also perturb stratospheric chemistry. 50-100 years. The methane concentration in the 2 x CH• atmosphere is a factor of 2.8 larger than the The Impact of Increased Methane on Atmospheric initial case at the ground and 2.2 in the upper Chemistry stratosphere. The one-dimensional atmospheric chemistry and The atmospheric chemistry of methane is transport model used here has been described in complex, particularly in the troposphere (see, eg., Ehhalt and Schmidt, 1978, Logan et al., 1981). A one-dimensional model cannot properly Copyright 1982 by the American Geophysical Union. simulate the latitudinal variations of species Paper number 2Ll122. like CO, NO, and OH that are important in 0094-8276/82/002L-112253.O0 tropospheric chemistry (Logan et al., 1981).
Geophysical Research Letters, 1982
A two-dimensional (2-D) chemical significantly affect conclusions regarding their model of the at... more A two-dimensional (2-D) chemical significantly affect conclusions regarding their model of the atmosphere is used to investigate lifetimes. However, calculated rates of removal the stratospheric removal rates of the for these molecules are strongly dependent on the chlorofluorocarbons CFC 11 (CFCI•) and CFC 12 transport description in the models since (CF2CI?). Assuming equivalent vertical transport photolysis can occur only after the CFCs reach rates,-one-dimensional (I-D) models are shown to altitudes with sufficient photon flux. overestimate the atmospheric lifetime of CFC 11 The transport descriptions in atmospheric by 410% because of their neglect of latitudinal models vary widely. One approach to choosing effects. The present Du Pont 1-D and 2-D models transport parameters is to fit experimental and have somewhat different effective transport rates theoretical concentration profiles for long-lived and give steady state CFC 11 atmospheric trace species like N20 (with a ground-level lifetimes of 75 and 60 years, respectively, •source) and ozone (with a stratospheric source). assuming no tropospheric destruction mechanism. •igure 1 compares the calculated vertical For CFC 12, the corresponding calculated profiles for N•O and O? obtained in the present lifetimes are 140 and 120 years. 1-D model (Mil{er et a., 1981b) with the global average obtained using the 2-D model (Miller et
Atmospheric Environment (1967), 1981
An updated version of a one-dimensional chemical model is described, together with a simple appro... more An updated version of a one-dimensional chemical model is described, together with a simple approach to diurnal calculations. The model is used to investigate the possible effects on model predictions of new chemistry, such as bromine and HOC1 chemistry, to compare calculated species profiles with experiment, and to evaluate, within the present chemical scheme, the magnitude of a variety of potential perturbations to stratospheric ozone. In particular the ozone depletion calculated for steady state fluorocarbon release at 1975 levels is 18.3 '% and it is shown that this number would be halved by doubling the current ground level N,O flux.