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• 1. [Article] The Relationship Between Precipitation and Temperature Over the Contiguous United States

  The correlation between monthly total precipitation and monthly mean temperature over the 80-year period from 1905 to 1984 at nearly 1000 stations in the contiguous United States was calculated and analyzed. ...

  Citation × Citation Citation Abstract Copy Title: The Relationship Between Precipitation and Temperature Over the Contiguous United States Author: Zhao, Weining, Khalil, M. A. K. Year: 1993 The correlation between monthly total precipitation and monthly mean temperature over the 80-year period from 1905 to 1984 at nearly 1000 stations in the contiguous United States was calculated and analyzed. Both local and field significances were tested by using statistical methods. Areas of both negative and positive precipitation-temperature correlations were found. Over most of the United States, summer precipitation and temperature were negatively correlated, which indicates that warm summers tended to be dryer. This is particularly true in the central and southern Great Plains. The area south of the Great Lakes covering the eastern portion of the Corn Belt was the only major area where a significant positive correlation was found in winter. Title: The Relationship Between Precipitation and Temperature Over the Contiguous United States Author: Zhao, Weining, Khalil, M. A. K. Year: 1993 The correlation between monthly total precipitation and monthly mean temperature over the 80-year period from 1905 to 1984 at nearly 1000 stations in the contiguous United States was calculated and analyzed. Both local and field significances were tested by using statistical methods. Areas of both negative and positive precipitation-temperature correlations were found. Over most of the United States, summer precipitation and temperature were negatively correlated, which indicates that warm summers tended to be dryer. This is particularly true in the central and southern Great Plains. The area south of the Great Lakes covering the eastern portion of the Corn Belt was the only major area where a significant positive correlation was found in winter. Close

• 2. [Article] Factors Affecting Methane Emissions from Rice Fields

  Methane emissions from rice fields are affected by a number of environmental and agricultural factors. We have analyzed our 7-year data set on methane emissions from rice fields in Tu Zu, China, to delineate ...

  Citation × Citation Citation Abstract Copy Title: Factors Affecting Methane Emissions from Rice Fields Author: Khalil, M. A. K., Rasmussen, R. A., Shearer, Martha J., Dalluge, R. W., Ren, Lixin, Duan, Chang-Lin Year: 1998 Methane emissions from rice fields are affected by a number of environmental and agricultural factors. We have analyzed our 7-year data set on methane emissions from rice fields in Tu Zu, China, to delineate the relationships between emissions and a number of variables that were measured at the same time. Our work was done in fields that were managed under prevailing agricultural practices of the region. Consequently, only the effect of factors that vary from year to year or during the growing season can be calculated. In our study we measured the effects of environmental variables (soil temperature, wind speed, sky cover) and agricultural factors (planting density, water level, rice cultivars, organic fertilizer amounts, yield). Of these variables, soil temperature had the most significant effect on methane emissions resulting in Q₁₀ values of about 2 (1.5–3). The effect of sky cover, and even water levels, was to change the soil temperature, which in turn affected the methane flux. Wind tended to increase emissions, possibly by agitation of the soil. Of the agricultural variables, planting density had the most significant but complex effect on methane emissions. We studied emissions from up to 4 times the normal planting density under otherwise similar agricultural conditions in the same fields. For a four fold increase in planting density the seasonal average emissions increased by about a factor of 2. Rice cultivars had a small but detectable effect. The amount of organic fertilizer and the yields did not affect methane emissions in our fields. The lack of an effect from the fertilizers is attributed to a saturation phenomenon whereby methane emissions do not respond to continual increases in organic material after some sufficiently high level. Title: Factors Affecting Methane Emissions from Rice Fields Author: Khalil, M. A. K., Rasmussen, R. A., Shearer, Martha J., Dalluge, R. W., Ren, Lixin, Duan, Chang-Lin Year: 1998 Methane emissions from rice fields are affected by a number of environmental and agricultural factors. We have analyzed our 7-year data set on methane emissions from rice fields in Tu Zu, China, to delineate the relationships between emissions and a number of variables that were measured at the same time. Our work was done in fields that were managed under prevailing agricultural practices of the region. Consequently, only the effect of factors that vary from year to year or during the growing season can be calculated. In our study we measured the effects of environmental variables (soil temperature, wind speed, sky cover) and agricultural factors (planting density, water level, rice cultivars, organic fertilizer amounts, yield). Of these variables, soil temperature had the most significant effect on methane emissions resulting in Q₁₀ values of about 2 (1.5–3). The effect of sky cover, and even water levels, was to change the soil temperature, which in turn affected the methane flux. Wind tended to increase emissions, possibly by agitation of the soil. Of the agricultural variables, planting density had the most significant but complex effect on methane emissions. We studied emissions from up to 4 times the normal planting density under otherwise similar agricultural conditions in the same fields. For a four fold increase in planting density the seasonal average emissions increased by about a factor of 2. Rice cultivars had a small but detectable effect. The amount of organic fertilizer and the yields did not affect methane emissions in our fields. The lack of an effect from the fertilizers is attributed to a saturation phenomenon whereby methane emissions do not respond to continual increases in organic material after some sufficiently high level. Close

• 3. [Article] Tracers of Wood Smoke

  Smoke from wood burning is a significant source of air pollution in many parts of the world. When several sources simultaneously cause air pollution, it is often difficult to determine how much comes from ...

  Citation × Citation Citation Abstract Copy Title: Tracers of Wood Smoke Author: Khalil, M. A. K., Rasmussen, R. A. Year: 2003 Smoke from wood burning is a significant source of air pollution in many parts of the world. When several sources simultaneously cause air pollution, it is often difficult to determine how much comes from wood burning. Woodsmoke has unique chemical characteristics that can be used as indicators, including elemental composition, particularly potassium and chlorine, the ratios of organic and elemental carbon, and gases such as methyl chloride. This paper deals with formulating and applying the chemical mass balance approach incorporating both gas- and aerosol-phase tracers to a study carried out at Olympia-Lacey in Washington. In this study, three types of tracers were measured simultaneously and used to estimate woodsmoke pollution during Winter, namely elemental composition and organic carbon in the particle phase and methyl chloride in the gas phase. The results from the different tracers are found to be in agreement. The air pollution at the study site was dominated by woodsmoke mostly from low-temperature combustion (about 80%), with additional but smaller contributions from oil furnaces (15%), automobiles (4%) and occasionally from other nearby sources. Title: Tracers of Wood Smoke Author: Khalil, M. A. K., Rasmussen, R. A. Year: 2003 Smoke from wood burning is a significant source of air pollution in many parts of the world. When several sources simultaneously cause air pollution, it is often difficult to determine how much comes from wood burning. Woodsmoke has unique chemical characteristics that can be used as indicators, including elemental composition, particularly potassium and chlorine, the ratios of organic and elemental carbon, and gases such as methyl chloride. This paper deals with formulating and applying the chemical mass balance approach incorporating both gas- and aerosol-phase tracers to a study carried out at Olympia-Lacey in Washington. In this study, three types of tracers were measured simultaneously and used to estimate woodsmoke pollution during Winter, namely elemental composition and organic carbon in the particle phase and methyl chloride in the gas phase. The results from the different tracers are found to be in agreement. The air pollution at the study site was dominated by woodsmoke mostly from low-temperature combustion (about 80%), with additional but smaller contributions from oil furnaces (15%), automobiles (4%) and occasionally from other nearby sources. Close

• 4. [Article] Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model

  The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million ...

  Citation × Citation Citation Abstract Copy Title: Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model Author: MacKay, R. M., Khalil, M. A. K. Year: 1995 The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million by volume (ppmv) to 700 ppmv) is reported. The model solves the two-dimensional primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables: zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p=rhoRT, and an assumed hydrostatic atmosphere, Deltap=rhogDeltaz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate. The model includes seasonal variations in solar intensity, including the effects of eccentricity, and has observed land and ocean fractions set for each zone. Seasonally varying values of cloud amounts, relative humidity profiles, ozone, and sea ice are all prescribed in the model. Equator to pole ocean heat transport is simulated in the model by turbulent diffusion. Title: Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model Author: MacKay, R. M., Khalil, M. A. K. Year: 1995 The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million by volume (ppmv) to 700 ppmv) is reported. The model solves the two-dimensional primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables: zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p=rhoRT, and an assumed hydrostatic atmosphere, Deltap=rhogDeltaz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate. The model includes seasonal variations in solar intensity, including the effects of eccentricity, and has observed land and ocean fractions set for each zone. Seasonally varying values of cloud amounts, relative humidity profiles, ozone, and sea ice are all prescribed in the model. Equator to pole ocean heat transport is simulated in the model by turbulent diffusion. Close

• 5. [Article] An Analysis of the Optimal Mix of Global Energy Resources and the Potential Need for Geoengineering Using the CEAGOM Model

  Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global ...

  Citation × Citation Citation Abstract Copy Title: An Analysis of the Optimal Mix of Global Energy Resources and the Potential Need for Geoengineering Using the CEAGOM Model Author: Anasis, John George, Khalil, M. A. K., Lendaris, George G., Butenhoff, Christopher L., Bluffstone, Randall Year: 2017 Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global population is key to addressing the climate change issue. The goal of this research is to examine the optimal mix of energy resources that should be deployed to meet a forecast global energy demand while still meeting desired climate targets. The research includes the unique feature of examining the role that geoengineering can play in this optimization. The results show that some form of geoengineering is likely to be needed by the middle of the 21st century as part of the optimal energy strategy in order to meet a specified climate goal of 580 ppm CO2-eq greenhouse gas concentration (or ≈2 °C average global temperature rise). The optimal energy mix would need to rely on energy efficiency, nuclear, geothermal, hydro, and wind energy for over 50% of global energy needs. In addition, the overall cost of the optimal energy mix is sensitive to the assumed amount of achievable energy efficiency, carbon taxes, deployment of electric vehicles, and the assumed discount rate. Title: An Analysis of the Optimal Mix of Global Energy Resources and the Potential Need for Geoengineering Using the CEAGOM Model Author: Anasis, John George, Khalil, M. A. K., Lendaris, George G., Butenhoff, Christopher L., Bluffstone, Randall Year: 2017 Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global population is key to addressing the climate change issue. The goal of this research is to examine the optimal mix of energy resources that should be deployed to meet a forecast global energy demand while still meeting desired climate targets. The research includes the unique feature of examining the role that geoengineering can play in this optimization. The results show that some form of geoengineering is likely to be needed by the middle of the 21st century as part of the optimal energy strategy in order to meet a specified climate goal of 580 ppm CO2-eq greenhouse gas concentration (or ≈2 °C average global temperature rise). The optimal energy mix would need to rely on energy efficiency, nuclear, geothermal, hydro, and wind energy for over 50% of global energy needs. In addition, the overall cost of the optimal energy mix is sensitive to the assumed amount of achievable energy efficiency, carbon taxes, deployment of electric vehicles, and the assumed discount rate. Close