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Your search keyword '"Levy, Hiram"' showing total 103 results
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103 results on '"Levy, Hiram"'

1. Christian Junge – a pioneer in global atmospheric chemistry

Author

Duce, Robert A., primary, Dickerson, Russell R., additional, Galbally, Ian E., additional, Galloway, James N., additional, Jaenicke, Ruprecht, additional, Keene, William C., additional, Lelieveld, Jos, additional, Levy, Hiram, additional, Prospero, Joseph M., additional, Schütz, Lothar, additional, Slemr, Franz, additional, and Winkler, Peter, additional

Published
2022
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4. GFDL’s ESM2 Global Coupled Climate–Carbon Earth System Models. Part II : Carbon System Formulation and Baseline Simulation Characteristics

Author

Dunne, John P., John, Jasmin G., Shevliakova, Elena, Stouffer, Ronald J., Krasting, John P., Malyshev, Sergey L., Milly, P. C. D., Sentman, Lori T., Adcroft, Alistair J., Cooke, William, Dunne, Krista A., Griffies, Stephen M., Hallberg, Robert W., Harrison, Matthew J., Levy, Hiram, Wittenberg, Andrew T., Phillips, Peter J., and Zadeh, Niki

Published
2013

10. Ozone measurements from a global network of surface sites

Author

Oltmans, Samuel J and Levy, Hiram, II

Subjects
Geophysics
Abstract

From a network of surface ozone monitoring sites distributed primarily over the Atlantic and Pacific Oceans, the seasonal, day-to-day, and diurnal patterns are delineated. At most of the NH (Northern Hemisphere) sites there is a spring maximum and late summer or autumn minimum. At Barrow, AK (70 deg N) and Barbados (14 deg N), however, there is a winter maximum, but the mechanisms producing the maximum are quite different. All the sites in the SH (Southern Hemisphere) show winter maxima and summer minima. At the subtropical and tropical sites, there are large day-to-day variations that reflect the changes in flow patterns. Air of tropical origin has much lower ozone concentrations than air from higher latitudes. At the two tropical sites (Barbados and Samoa), there is a marked diurnal ozone variation with highest amounts in the early morning and lowest values in the afternoon. At four of the locations (Barrow, AK; Mauna Loa, HI; American Samoa; and South Pole), there are 15- through 20-year records which allow us to look at longer term changes. At Barrow there has been a large summer increase over the 20 years of measurements. At South Pole, on the other hand, summer decreases have led to an overall decline in surface ozone amounts.

Published
1994

12. Seasonal cycle of surface ozone over the western North Atlantic

Author

Oltmans, Samuel J. and Levy, Hiram, II

Subjects
North Atlantic Ocean -- Research, Tropospheric circulation -- Research, Atmospheric ozone -- Measurement, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Fluctuations in tropospheric ozone levels over the western North Atlantic probably result from natural atmospheric circulation rather than from pollution. Some environmentalists have feared that air pollution from North America and Europe might be adding to ozone over the North Atlantic. However, measurements taken over Bermuda and Barbados indicate that the sometimes elevated ozone levels were caused by ozone being brought down from the uncontaminated upper troposphere. In general, Barbados and Bermuda's ozone levels were less than the US and Canada's levels.

Published
1992

14. The impacts of changing transport and precipitation on pollutant distributions in a future climate

Author

Fang, Yuanyuan, Fiore, Arlene M., Horowitz, Larry W., Gnanadesikan, Anand, Held, Isaac, Chen, Gang, Vecchi, Gabriel, and Levy, Hiram

Subjects
Geochemistry, Atmospheric chemistry, Climatic changes--Forecasting, Climatic changes--Mathematical models, Tropospheric chemistry, Air--Pollution--Measurement, sense organs, Climatic changes
Abstract

Air pollution (ozone and particulate matter in surface air) is strongly linked to synoptic weather and thus is likely sensitive to climate change. In order to isolate the responses of air pollutant transport and wet removal to a warming climate, we examine a simple carbon monoxide–like (CO) tracer (COt) and a soluble version (SAt), both with the 2001 CO emissions, in simulations with the Geophysical Fluid Dynamics Laboratory chemistry-climate model (AM3) for present (1981–2000) and future (2081–2100) climates. In 2081–2100, projected reductions in lower-tropospheric ventilation and wet deposition exacerbate surface air pollution as evidenced by higher surface COt and SAt concentrations. However, the average horizontal general circulation patterns in 2081–2100 are similar to 1981–2000, so the spatial distribution of COt changes little. Precipitation is an important factor controlling soluble pollutant wet removal, but the total global precipitation change alone does not necessarily indicate the sign of the soluble pollutant response to climate change. Over certain latitudinal bands, however, the annual wet deposition change can be explained mainly by the simulated changes in large-scale (LS) precipitation. In regions such as North America, differences in the seasonality of LS precipitation and tracer burdens contribute to an apparent inconsistency of changes in annual wet deposition versus annual precipitation. As a step toward an ultimate goal of developing a simple index that can be applied to infer changes in soluble pollutants directly from changes in precipitation fields as projected by physical climate models, we explore here a “Diagnosed Precipitation Impact” (DPI) index. This index captures the sign and magnitude (within 50%) of the relative annual mean changes in the global wet deposition of the soluble pollutant. DPI can only be usefully applied in climate models in which LS precipitation dominates wet deposition and horizontal transport patterns change little as climate warms. Our findings support the need for tighter emission regulations, for both soluble and insoluble pollutants, to obtain a desired level of air quality as climate warms.

Published
2011
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18. Toward a new generation of ice sheet models

Author

Little, Christopher M., Oppenheimer, Michael, Alley, Richard B., Balaji, Venkatramani, Clarke, Garry K.C., Delworth, Thomas L., Hallberg, Robert, Holland, David M., Hulbe, Christina L., Jacobs, Stan, Johnson, Jesse V., Levy, Hiram, Lipscomb, William H., Marshall, Shawn J., Parizek, Byron R., Payne, Antony J., Schmidt, Gavin A., Stouffer, Ronald J., Vaughan, David G., Winton, Michael, Little, Christopher M., Oppenheimer, Michael, Alley, Richard B., Balaji, Venkatramani, Clarke, Garry K.C., Delworth, Thomas L., Hallberg, Robert, Holland, David M., Hulbe, Christina L., Jacobs, Stan, Johnson, Jesse V., Levy, Hiram, Lipscomb, William H., Marshall, Shawn J., Parizek, Byron R., Payne, Antony J., Schmidt, Gavin A., Stouffer, Ronald J., Vaughan, David G., and Winton, Michael

Published
2007

22. Temporal variability of summer-time ozone and aerosols in the free troposphere over the eastern North Atlantic

Author

Prospero, Joseph M., Schmitt, R., Cuevas Agulló, Emilio, Savoie, D. L., Graustein, W. C., Turekian, K. K., Volz-Thomas, A., Díaz, A., Oltmans, Samuel J., and Levy, Hiram

Subjects
Aerosols, Particles, Troposfera, Troposphere, Aerosoles, Contaminación urbana, Urban pollution
Abstract

In the free troposphere over Tenerife in the summer, O3 concentrations are anti-correlated with major pollutant aerosols (nss-SO = 4 and NO−3) and with 210Pb, a tracer for boundary layer sources. In contrast, O3 is highly correlated with 7Be, a product of cosmic ray interactions in the upper troposphere and stratosphere. This suggests that natural O3 sources (i.e. the stratosphere) might be playing an important role. Nonetheless our results do not preclude the possibility that substantial amounts of pollution-related O3 could be transported in the free troposphere. However, to be consistent with our results, the transport mechanisms would have to incorporate efficient processes for the removal of pollutant aerosol species and 210Pb.

Published
1995

30. Toward a New Generation of Ice Sheet Models

Author

Little, Christopher M., primary, Oppenheimer, Michael, additional, Alley, Richard B., additional, Balaji, Venkatramani, additional, Clarke, Garry K. C., additional, Delworth, Thomas L., additional, Hallberg, Robert, additional, Holland, David M., additional, Hulbe, Christina L., additional, Jacobs, Stan, additional, Johnson, Jesse V., additional, Levy, Hiram, additional, Lipscomb, William H., additional, Marshall, Shawn J., additional, Parizek, Byron R., additional, Payne, Antony J., additional, Schmidt, Gavin A., additional, Stouffer, Ronald J., additional, Vaughan, David G., additional, and Winton, Michael, additional

Published
2007
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