B33A-0226 1340h
Modeling Seasonality in German Carbon Dioxide Emissions From Fossil Fuel Consumption
A method is developed to determine seasonal fossil fuel consumption patterns by using monthly sales data to estimate the relative monthly proportions of the total annual carbon dioxide emissions for Germany. From these data, the goal is to develop mathematical models that describe the seasonal flux in consumption for each type of fuel, as well as the total emissions for this nation. The time series models have two components. First, the general long-term trend is determined with regression models. After removing the general trend, two alternatives are considered for modeling the seasonality. The first alternative uses the mean of the monthly proportional consumption to predict the seasonal distribution. A second alternative is to use an ordinary least squares autoregressive model. This model is chosen for its ability to accurately describe dependent data and for its predictive capacity. It also has a meaningful interpretation, as each coefficient in the model quantifies the dependency for each corresponding time lag. Most importantly, it is dynamic, and able to adapt to anomalies and changing patterns. To model the monthly fuel consumption, the annual trend is combined with the seasonal model. The models for each fuel type are then summed together to predict the total carbon dioxide emissions. The prediction error is estimated with the root mean square error from the actual estimated emission values. The result is a quantitative description of carbon dioxide emissions from fossil fuel consumption.
B33A-0227 1340h
A Preliminary Examination of Monthly Consumption Patterns of Petroleum in European Countries
Previous studies of carbon dioxide emissions from petroleum products in European countries have shown changes with time that can be correlated with demand on annual and monthly time scales. This study will build on these previous studies by including additional European countries. This study will also aim to identify the factors that determine the pattern of monthly consumption in countries that span 35 degrees in latitude and various socioeconomic foundations (e.g., mean monthly temperature and hence heating/cooling needs, lifestyle choices, national policy decisions, etc.). This work should increase our understanding of the magnitude and pattern of sub-annual variations in emissions of greenhouse gases from petroleum consumption in Europe.
B33A-0228 1340h
Radiocarbon Dates Link Marine Incursion and Neoglacial Ice Terminus Advance With Tlingit Ethnohistory and Archeology in Lower Glacier Bay
Radiocarbon dates from wood, organic sediments, and marine shells were collected from eroded beach terraces and upper beach sediments in the Beardslee Islands and Berg Bay in Glacier Bay National Park, Alaska. These provide a timetable for the the outwash plain construction and final advance of the Late Neoglacial glacier front over this outwash plain into lower Glacier Bay. On Kidney Island in the central Beardslee Islands, marine sediments containing {\it Macoma baltica} shells were deposited 4310 +/- 40 years BP. Outwash from advancing up-bay glaciers, buried these sediments and created terrestrial substrates upon which forests existed by 1630 +/- 60 BP and 1300 +/- 50 yrs BP. Final ice advance over this forested outwash plain occurred after 430 +/- 60 BP (1430 to 1510 AD) on Kidney Island. This ice arrived at the southern edge of Lester Island in Bartlett Cove after 370 +/- 50 BP (1440 to 1520 AD); preceding the arrival of George Vancouver in 1794 AD. In nearby Icy Straits, archeological investigations have yielded some of the oldest dates of human occupation in the region at 10,180 +/- 800 uncorrected years BP (Ackerman, 1968). In Glacier Bay's ethno-historically rich areas of Bartlett Cove, the Beardslee Islands and Berg Bay the Huna people have names for places and narratives that describe late Neoglacial landscapes. {\bf S'\'{e} Shuyee} is the "area at the end of the glacial mud", {\bf L'awsha Shakee Aan} "town on top of the glacial sand dunes". There are accounts of villages overrun by surging glaciers, and a name for the bay {\bf Sit' eeti Geeyi} that translates as "bay in place of the glacier". These dates provide linkage between the geological, archeological, and ethnohistorical evidence that chronicles the history of the Huna people in this dynamic glacier marine environment.
B33A-0229 1340h
The role of climate and humans in shaping interannual variability in biomass burning emissions: The Global Fire Emissions Dataset (GFED v2)
The amount of carbon that is lost from the biosphere to the atmosphere as a result of biomass burning is poorly quantified, but these emissions are thought to contribute substantially to interannual variability in the growth rate of many atmospheric trace gases and are a main source of aerosols. Traditionally, biomass burning emissions are quantified using field work or satellite derived information on burned area and fuel loads ("bottom up"), but recent studies using inversion techniques and atmospheric measurements ("top down") have provided new means to constrain regional and global levels of fire emissions. Here we have combined lessons learned from several recent inversion studies, with new MODIS data, to improve and extend an existing "bottom up" biomass burning dataset (the Global Fire Emissions Dataset). The dataset now covers the 1997-2003 period but will be updated whenever more recent input data is available and uses a new cluster-based algorithm with MODIS data for estimating burned area. We show how interannual variability in precipitation (tropics) and temperature (boreal region) drives the yearly variations in emissions. Interannual variability of emissions is mostly due to variations in deforestation rates, mainly in tropical America and Southeast Asia, while interannual variability in savanna regions is relatively low. Year-to-year variability is also large in the boreal region. Although most of the area burned occurs in the savannas of Africa, we find that absolute emissions in tropical America exceed those from Africa.
B33A-0230 1340h
Seasonal Variation Of Atmospheric CO2 And Carbon Flux From Biosphere Simulated By A Global Coupled Model
To investigate contribution of the biosphere to atmospheric CO2, a simulation was implemented using a global transport model coupled with a biosphere model. The transport model, which was developed by Iguchi and Kida, divides the atmosphere into grid boxes and calculates fluxes between boxes. So it surely conserves total mass of tracers. Sim-CYCLE, the biosphere model developed by Ito and Oikawa, calculates carbon dynamics within the plant and soil of each grid area. In the coupled model, carbon absorption by photosynthesis and emission by respiration and decomposition calculated by Sim-CYCLE are summed up to surface CO2 fluxes of the transport model. Oppositely, CO2 distribution calculated by the transport model is input to Sim-CYCLE. Both models need input data of the atmosphere or soil. In the simulation, 1990 ECMWF/TOGA data set was used for the transport model, and 1990 NCEP/NCAR re-analysis data set was used for Sim-CYCLE. Also NASA/GISS carbon exchange data set was used as carbon flux from fossil fuel consumption, land use change, and ocean. Result of the simulation was compared with CO2 distribution interpolated from 1990 WMO/WDCGG monthly observation data set. Annual and zonal mean CO2 values calculated in the simulation become higher than those observed. Global and annual carbon absorption by the biosphere calculated by Sim-CYCLE was 1.24GtC. Monthly and zonal mean computed CO2 distributions showed seasonal variation that is similar to observation from winter to summer, but not from summer to winter. This result requires the biosphere model more precise reproduction of leaf falling. Seasonal variations of computed and observed CO2 at observation sites were also compared. At most of the sites, the month of the minimum CO2 computed is later than that observed. As concerns seasonal variation of carbon flux from the biosphere, result of the simulation and NASA/GISS carbon flux data set of vegetation were compared. Computed flux by Sim-CYCLE showed longer absorption period on high latitudes in Northern Hemisphere than NASA/GISS data. As mentioned above, this may be because leaf fall is too late and photosynthesis period of vegetation is too long on these latitudes. On low latitudes in South Hemisphere, phase of seasonal variation of carbon flux computed by Sim-CYCLE looks opposite to that of NASA/GISS data. One of the primal reasons is thought to be that area of tropical deciduous forest is too small in this model, and another is that Sim-CYCLE showed seasonal variation of carbon flux from tropical rain forest that is emitting in summer and absorbing in winter. The latter seasonal variation may be true of real evergreen vegetation.
B33A-0231 1340h
Regional Differences in CO2 Fertilization Effects
Free Air Carbon Enrichment (FACE) experiments indicate increased atmospheric CO2 enhances plant photosynthetic rates (the CO2 fertilization effect). These experiments also indicate other factors, such as water and nutrient availability, can limit the effects of CO2 fertilization. To isolate regional differences in CO2 fertilization, we ran global simulations using observed concentrations of CO2 from the global flask network and the National Centers for Environmental Prediction (NCEP) reanalysis (1958-2002) as input to the Simple Biosphere Model, version 3 (SiB3). SiB3 predicts photosynthetic rates using the Ball-Berry stomatal conductance equation, which allows SiB3 to respond to variability and trends in observed CO2 concentration. SiB3 also responds to other factors that limit or influence the photosynthetic rate, such a relative humidity and soil moisture. Using SiB3, we isolated those regions with the strongest and weakest CO2 fertilization. In general, soil moisture limited the effects of CO2 fertilization: dry and semi-arid regions showed the smallest CO2 fertilization, while moist regions showed the largest.
B33A-0232 1340h
The Influence of Biospheric Temperature Acclimation and Choice of Temperature Response Function on Feedbacks in Coupled Climate-Carbon Cycle Models
Future CO$_2$ concentrations and global mean temperatures are higher in general circulation models that include an interactive global carbon cycle than in those without the coupling. However, the magnitude of this positive climate-carbon cycle feedback varies among models. The differences can largely be attributed to terrestrial biosphere response, with higher ecosystem respiration at higher temperatures an important contributor. We are thus investigating the impact of different models of the temperature response of ecosystem respiration on simulated climate-carbon feedbacks. We focus on temperature acclimation of heterotrophic (soil) respiration (R$_h$), because acclimation of R$_h$ to warmer temperatures is hypothesized to reduce climate-carbon feedbacks. We have implemented alternative temperature functions for R$_h$, including those with temperature acclimation, in a site-scale ecosystem model (LoTEC), a global terrestrial biogeochemistry model (GTEC 2.0), a global integrated terrestrial biosphere model (IBIS 2.5), and a coupled climate-carbon cycle model (INCCA), which couples the Parallel Climate Model (PCM) with IBIS. Simulations with the ecosystem and uncoupled biosphere models show that the choice of temperature function strongly influences the accumulation of carbon in soil over time and space, and these differences in soil carbon stocks influence the release of CO$_2$ to the atmosphere via first order, mass-dependent decay dynamics. These indirect effects are more important in determining climate-carbon feedbacks at warmer temperatures than the primary effects of temperature on rates of respiration per unit mass of carbon. In some simulations, total respiratory flux of carbon to the atmosphere in projected warmer climates was virtually the same with or without acclimation because of compensating differences in carbon accumulation at earlier cooler temperatures. When the coupled climate-carbon model is forced by historical fossil-fuel emissions, total global soil carbon increases at 0.5 Gt C y$^{-1}$ when R$_h$ is modeled with a temperature response function exhibiting moderate acclimation to temperature but declines at 0.3 Gt C y$^{-1}$ when R$_h$ is modeled with a simple Q10 temperature function showing no acclimation. These results suggest that the choice of temperature functions for terrestrial R$_h$ can influence simulated climate-carbon feedbacks in coupled models. However, the influence is largely through indirect effects on soil carbon stocks, rather than acclimation or other differences in temperature dependent rates per se. Differences among temperature functions in the range of 10-35 $^0$C are likely more important than differences under warmer, but rarely experienced, conditions. Accordingly, when choosing a temperature response function, careful attention should be given to accurate simulation of soil respiration at historically prevailing temperatures.
B33A-0233 1340h
Solar dimming and urban aerosol distribution in New York Metropolitan area
One impact of human activities on the urban and suburban environment is the dimming of sunlight due to urban air pollution and intensified haze. The spreading of urban aerosol and the optical efficiency depends on the size distribution of the particles and the vertical distribution. Reduced transparency of the atmosphere leads to an increase in scattered light compared to direct sunlight and an overall reduced total solar flux at the surface due to absorption in the atmosphere and backscattering of light to space. The modified solar flux cools the surface and suppresses evaporation and turbulent mass exchange in urban and suburban areas. Increase in diffuse sunlight can also have a positive effect on plant productivity due to increased actinic flux. Hence consequences for the biogeochemical cycles can be expected in urban and suburban areas. The quantification and variability of these effects were investigated in a pilot project in summer 2003 and 2004 where measurements of Aerosol Optical Thickness (AOT) at several wavelengths and particle number concentration for multiple size ranges were made in pilot fashion with the initial goal of better understanding horizontal and vertical distribution of aerosols near a major metropolitan center. Large spatial variability of atmospheric transparency in the New York Metropolitan area was observed in transects through New York City and Long Island to New Jersey in a field campaign in July 2003. Vertical profiles of AOT and particle number concentration were collected on board hot-air balloon flights in July 2004 that were launched from rural/suburban New Jersey. One evening flight was made in clear conditions and 4 evening flights where made under varying hazy conditions with the sunphotometer looking west. One sunrise flight was made in hazy conditions with the sunphotometer looking east through the city. Here we highlight a few results from two evening flights; additional data and plans of future work will be discussed in the poster. On July 6, during clear conditions, AOT at 500 nm is very low (depth integrated mean of 0.07) and fairly constant as a function of altitude (-0.003 change per 100 meters). Particle number concentration in the 0.3 - 0.5 $\mu$m size range are also relatively low but have a steeper vertical gradient than AOT and abruptly drops to near zero above the boundary layer (1200 meters on that flight). The mean AOT at 500 nm (0.5) is a factor of 7 higher on the hazy evening of July 20th and its vertical gradient is also ca. a factor of 7 higher (-0.02 per 100 meters). Particle number concentrations in the the 0.3 - 0.5 $\mu$m size range on this hazy evening were a factor of 3 to 4 higher than the clear evening and fairly constant with altitude, only appreciably dropping off above 1600 meters.
B33A-0234 1340h
Natural Abundance of Mass 47 in CO$_{2}$ Emitted in Car Exhaust and Human Breath
Atmospheric CO$_{2}$ is widely studied using records of concentration, $\delta^{13}$C and $\delta^{18}$O, although the number and variability of sources and sinks prevents these alone from uniquely defining the budget. CO$_{2}$ of mass 47 (mainly $^{13}$C$^{18}$O$^{16}$O) provides an additional potential tracer, but little is known about its ability to differentiate among various budget components. We present study of differences in $^{13}$C$^{18}$O$^{16}$O abundance between combustion and respiration. We define $\Delta$47 as the difference in permil between the measured R47 (=[mass 47]/[mass 44]) and R47 expected for CO$_{2}$ whose isotopes are distributed randomly among all isotopologues. Previous studies have shown that $\Delta$47 values at thermodynamic equilibrium vary between zero at 1000\deg C and 0.9\permil at room temperature, raising the possibility that it could differentiate between CO$_{2}$ produced by high temperature processes, such as combustion, and that produced in respiration. Values of $\Delta$47 are non-linear in mixing. Therefore, it is useful to discuss the $\delta$47=(R47/R47$_{ST}$-1)1000, where R47$_{ST}$ is the R47 expected for CO$_{2}$ having $\delta^{13}$C-VPDB=0, $\delta^{18}$O-VSMOW=0 and $\Delta$47=0. We used a Keeling plot approach to estimate $\delta^{13}$C, $\delta^{18}$O, $\delta$47 and $\Delta$47 in CO$_{2}$ from car exhaust and from human breath. Air sampled at 10am in the Caltech campus in Pasadena, CA, varied in CO$_{2}$ concentration from 383 to 404ppm, in $\delta^{13}$C and $\delta^{18}$O from -9.2 to -10.2\permil and from 40.7 to 42.0\permil, respectively, in $\delta$47 of from 32.6 to 34.0\permil, and in $\Delta$47 from 0.73 to 0.96\permil. We then sampled at varying distances from a car exhaust pipe. The intercepts in Keeling plots defined by these data, reflecting the car exhaust end-member, were similar to the values obtained very close to the exhaust pipe: $\delta^{13}$C was found to equal -24.4$\pm$0.2\permil, similar to the measured value of the gasoline used; $\delta^{18}$O =30.0$\pm$0.4\permil; $\delta$47=6.7$\pm$0.6\permil; and $\Delta$47=0.41$\pm$0.03\permil. Both $\delta^{18}$O and $\Delta$47 are consistent with that expected for thermodynamic equilibrium at 200\deg C between water and CO$_{2}$ generated by combustion of gasoline-air mixtures. This temperature is lower than that of the catalytic converter, suggesting re-equilibration in the cooling exhaust as it travels through the tail pipe. This can explain why the $\delta^{18}$O of CO$_{2}$ from car exhaust is substantially greater than that of O$_{2}$ in air. Samples of CO$_{2}$ in human breath had $\delta^{13}$C and $\delta^{18}$O values broadly similar to those of car exhaust (-22.3$\pm$0.2 and 34.4$\pm$0.3\permil, respectively), $\delta$47 of 13.5$\pm$0.4\permil, but $\Delta$47 of 0.74$\pm$0.02\permil, far higher than exhaust and similar to that of background Pasadena air. $\delta^{13}$C of human breath is similar to that of car exhaust, much as other respiration and fossil-fuel sources of CO$_{2}$ generally overlap. Similarly, $\delta^{18}$O of human breath and soil respiration are close to that of car exhaust. Therefore, conventional stable isotope constraints do not easily differentiate fossil-fuel and respiratory sources. In contrast, the $\Delta$47 value of CO$_{2}$ from car exhaust is easily differentiated from those of CO$_{2}$ in human breath, largely due to enhanced thermodynamic stability of $^{13}$C$^{18}$O$^{16}$O at the low temperatures characteristic of respiration. Hence, $\Delta$47 is a potentially useful tracer to distinguish anthropogenic, mostly combustion, CO$_{2}$ sources from natural, low temperature, sources.
B33A-0235 1340h
Changes in Concentration and Isotopic Ratios of CO$_{2}$ in Air in the Los Angeles Basin, California, Between 1972 and 2003
Air in the Los Angeles Basin (California) is known for its high levels of pollution, due in large part to burning of fossil fuels for industry and transportation. CO$_{2}$ is a major product of the combustion process. We compare concentrations and isotopic compositions of CO$_{2}$ in air samples collected in 1998-2003 with samples collected in 1972-1973 in almost the same location on the Caltech campus in Pasadena. We also compare our results to analyses of air from unpolluted areas reported by the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) from oceanic sites at the same latitude. CO$_{2}$ concentrations have increased by $\sim$50 ppm (averaging 355 ppm in 1972-1973 and 402 ppm in 1998-2003), but the ranges of the carbon and oxygen isotopic ratios have not changed significantly ($\delta$$^{13}$C$_{VPDB}$ was -7.9 to -13.5$\permil$ in 1972-1973 and -8.0 to -14.1$\permil$ in 1998-2003; $\delta$$^{18}$O$_{VPDB-CO2}$ was -4.35 to -0.60$\permil$ in 1972-1973 and -4.29 to 0.15$\permil$ in 1998-2003). Each data set displays a significant correlation between $\delta$$^{13}$C and 1/ CO$_{2}$ concentration. The intercepts at infinite CO$_{2}$ are very similar for both 1972-1973 (-31.7$\permil$) and 1998-2003 (-30.6$\permil$). Mass balance calculations show that this is consistent with the changing mix of natural gas and petroleum products burned in the region provided the countries of origin of the petroleum products are taken into account. The seasonally averaged 1998-2003 CO$_{2}$ inventory in Pasadena can be explained by a local contribution of 20-39 ppm (i.e., 5-11% relative) to clean air for this latitude (based on the NOAA data). This additional CO$_{2}$ is characterized by an average $\delta$$^{13}$C of -30.3$\permil$ and $\delta$$^{18}$O -9.20$\permil$. Because of the mild climate in southern California, larger amounts of isotopically light fossil fuel are consumed for energy generation for air conditioning during the summer than during the winter for heating. This offsets the effects of vegetation due to photosynthesis/respiration and masks the periodic seasonal variation observed in clean air sites at the same latitude.
B33A-0236 1340h
Carbon Cycle Sensitivity to Climate Change: Results from a Comprehensive GCM-Based Climate and Carbon Cycle Model
We use an interactive global climate and carbon cycle model to perform simulations of climate change from 1870 AD to 2100 AD forced by anthropogenic emissions of greenhouse gases. The goal of this effort is to include and better understand feedbacks between the climate system and the carbon cycle. We use the Parallel Climate Model 2 (PCM-2) developed at NCAR as our climate model. The PCM-2 includes a version of NCAR's CCM3 for the atmospheric GCM and a version of the POP model for the ocean GCM. The ocean carbon model is based on OCMIP protocols, but modified to eliminate the phosphate-restoring restriction. The terrestrial biosphere model is IBIS-2 which simulates biophysical and biogeochemical surface fluxes and includes a dynamic vegetation model. Three simulations are performed using three different IPCC emission scenario: A1B, A2 and B1. These scenarios correspond to moderate, aggressive and low rates of fossil fuel burning in the 21st century. All cases assume historical greenhouse emissions and land use change emissions up to year 2000. The range of emissions rates by year 2100 that force these 3 experiments encompasses the range projected by Third Assessment Report of IPCC. We will discuss the sensitivity of model's carbon cycle for this range of global climate change. We will specifically discuss the sensitivity of terrestrial carbon uptake to changes in the magnitude of global warming.
B33A-0237 1340h
Exploring Relationships between North American Urban Form and Rates of Urban CO$_{2}$ Emissions: A System Dynamics Approach
Cities are the locus of North America's most intense consumption of fossil fuels. Thus the rate and character of urbanization influence the rate of urban CO$_{2}$ released into the global atmosphere. The rate of rural-to-urban land conversion, and changes in the population density of urban land, are influenced by coupled changes in urban demographics and the local economy. Urban sprawl (a rapid expansion of urban land with low population densities) is governed by a self-reinforcing feedback effect between urban transportation infrastructure investments (road building) and urban land development where road building begets new urban neighborhoods that, in turn, induce more road building that begets additional new neighborhoods. If unrestrained, this feedback effect leads to the unrestrained expansion of urban sprawl, urban vehicular travel and traffic congestion. This self-reinforcing feedback loop forms a key dynamic that controls the rate at which CO$_{2}$-emitting fossil fuels are burned for transportation, electricity production, heating, and commercial/industrial processes. In a rapidly sprawling city residents must travel increasingly greater distances between work, shopping, and home while commercial service vehicles must travel to increasingly remote residential locations. The increasing number of vehicle trips and vehicle miles traveled, combined with the growing prevalence of ever-lower density urban land development, leads to a rapid increase in mobile and stationary CO$_{2}$ emissions. A more compact and punctuated form of urban development with higher-density and mixed-use urban activity centers leads to reduced CO$_{2}$ emissions. Those who shape urban development policy are often unconcerned by increasing CO$_{2}$ emissions unless they can be linked to: (1) local concerns about criteria air pollutant emissions and air quality, (2) the dependency of federal infrastructure funding on meeting ambient air quality standards, and (3) the consequences of human exposure to health risks associated with declining air quality. The dynamic simulation of urban systems demonstrates that a suite of policies can be found to diminish sprawl and defeat traffic congestion thereby safeguarding the vitality a city. A systems thinking approach, facilitated by a community engagement process, has further enabled community opinion leaders and policy makers to map the key features, linkages and feedbacks of a complex, CO$_{2}$-emitting urban ecosystem. A corresponding lumped-parameter, simulation model provides a framework for decision makers and stakeholders to explore the consequences of alternative options for managing urban growth, sprawl and congestion while also reducing CO$_{2}$ emissions.
http://slvairshed.utah.edu
B33A-0238 1340h
Carbon Dioxide Concentrations in the Atmosphere of Underground Environments as Tracers of Climatic Changes
Carbon dioxide is often observed in concentrations much higher than in external atmosphere inside underground environments, both of natural (caves) and artificial (galleries) origin. With the aim of evaluating the possible use as a tracer of climatic changes, CO2 static concentrations have been discontinuously monitored since the year 2000 in the atmosphere of the Carburangeli and Santa Ninfa Caves, located in a limestone karst areas near the city of Palermo and in a gypsum karst area in the Belice Valley (Sicily, Italy) respectively. The measurements have been acquired with a portable 0-9999 ppm infrared spectrometer, together with dripping waters rate, air temperature and relative humidity (both continuous and discontinuous measures); free CO2 contents of dripping waters have been determined with titration method. Highest values were recorded in Carburangeli cave, when underground air temperature is colder than external atmosphere: in this case air circulation is blocked and carbon dioxide concentration arises. Very high concentrations of carbon dioxide were recorded also in winter, when hot winds blew from SE. The main source for carbon dioxide has been individuated in the dripping waters, which rate depends on the dynamic of rainfall events. These preliminary data suggests that carbon dioxide concentrations in the underground atmosphere of Carburangeli cave strongly depend on the delicate equilibria between internal and external air temperatures and dripping waters rate, being all these parameters affected by possible climate changes. Atmospheric warming and intensification of rainfalls rate might be traced by variations in the space-time dynamic of carbon dioxide inside the cave.
B33A-0239 1340h
The Economic Impact of Climate, CO2, and Tropospheric Ozone Effects on Crop Yields in China, the US, and Europe
Multiple environmental changes that may occur over the next century will affect crop productivity. Some of these effects are likely to be positive (CO2 fertilization), some negative (tropospheric ozone damage), and some may be either positive or negative (temperature and precipitation). Climate effects may operate in either direction because the direction of change may differ across regions (more precipitation in some areas and less in others) and warming may increase growing season lengths in cold-limited growing areas while acting as a detriment to productivity in areas with already high temperatures. Previous work has shown the effects of these combined environmental changes on carbon sequestration in natural and managed systems, and valued these effects in terms of avoided costs of fossil fuel carbon abatement. The more direct and obvious economic effect, however, is the changes in crop yields implied by these vegetation effects. Here we use the MIT Integrated Global Systems Model (IGSM) to analyze the potential economic impact of changes in crop yields. For this work we have augmented the Emissions Prediction and Policy Analysis (EPPA) model by further disaggregating the agricultural sector. This allows us to simulate economic effects of changes in yield (i.e. the productivity of cropland) on the regional economies of the world, including impacts on agricultural trade. The EPPA model includes multiple channels of market-based adaptation, including input substitution and trade. We are thus able to examine the extent to which market forces contribute toward adaptation and thus modify the initial yield effects. We examine multiple scenarios where tropospheric ozone precursors are controlled or not, and where greenhouse gas emissions are abated or not. This allows us to consider how these policies interact. We focus on China, the US, and Europe which are currently regions with high levels of tropospheric ozone damage. We find significant negative effects of tropospheric ozone on crop yields and the agricultural economy under current conditions. Our results compare favorably with other methods that show damages of the same level. Our future simulations depend highly on whether tropospheric ozone precursors are controlled in the future. While policies exist in countries to limit tropospheric ozone as a local/regional pollutant, a growing problem particularly in the northern latitudes that include our focus regions, will be that background levels of ozone could reach levels such that it will be difficult for any one country to control its ozone levels without similar control efforts in other regions. This preliminary work highlights the importance of these policy interactions, and emphasizes the need for improved modeling of the atmospheric transport of pollutants.
B33A-0240 1340h
Analyzing the Influence of Tropical Deforestation on the Northern Hemisphere Climate Through Atmospheric Teleconnections
Previous studies have identified the regional-scale climate response to tropical deforestation through changes to the biophysical exchanges of water, energy, and momentum between the land surface and the atmosphere; however, little is known about the effects of tropical deforestation on the global climate. Current research has focused on climate responses in the extratropics with little analyses of the mechanisms responsible for propagating the signal out of the tropics. Here, we present a detailed study of the physical processes important in propagating a signal resulting from deforestation out of the tropics to the Northern Hemisphere in winter. Through complete deforestation of the tropics we analyze changes to the deep moist convection and reductions in high-level outflow as well as the anomalous forcing of Rossby waves out of the tropics. Our study indicates that an anomalous Rossby wave forcing resulting from tropical deforestation modifies the East Asian Jet strength and structure as well as other features of the Northern Hemisphere mean circulation patterns. Furthermore, our results indicate that tropical deforestation can amplify different modes of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) through a redistribution of atmospheric mass caused by fundamental changes to the strength and positioning of the storm tracks and synoptic eddy activity. Different modes of variability cause different climate responses across Siberia and result in anomalous changes to the low-level winds that can significantly enhance the advection of warm air into Eurasia from the south and west. While theoretical, our approach illustrates the potentially important processes connecting regional-scale changes in the tropical climate to regional-scale changes in the extratropics.
B33A-0241 1340h
Was the Enhanced CO2 Sink Following the Mt. Pinatubo Eruption Driven by an Increase in Diffuse Radiation?
Was the Enhanced CO2 Sink Following the Mt. Pinatubo Eruption Driven by an Increase in Diffuse Radiation? Following the Mt. Pinatubo eruption in 1991 there was a sharp decrease in the atmospheric CO2 growth rate. It is believed that this decrease was caused by an anomalous strong terrestrial sink (approx. 2PgC/yr) in the northern hemisphere. This strong sink is hard to explain, since the global low temperatures that followed the eruption (as a result of the injecting of volcanic aerosols to the stratosphere) were expected to reduce photosynthesis rate. There are currently two competing explanations for the enhanced sink. The first is that soil respiration rate declined more than photosynthesis rate, while the second suggests that the increase in the fraction of diffused radiation, as a result of the aerosol loading, caused an increase in photosynthesis. In this study we used a biogeochemical model (CASA) linked to an atmospheric tracer model (MATCH) with interannually varying transport, to predict the atmospheric CO2 response to the various hypotheses for the enhanced sink. By comparing the modeled CO2 growth rate, and seasonal minimum with observation from the CMDL global CO2 monitoring network, we found that global Net Primary Production could not have increased following the eruption. We also found that the enhanced sink cannot be explained by decreased respiration alone, and thus can be only explained by several land and ocean sink mechanisms acting in concert.
B33A-0242 1340h
The Global Land-Atmosphere Coupling Experiment (GLACE): Multi-model analysis of global land-atmosphere coupling strength
The Global Land-Atmosphere Coupling Experiment (GLACE), a joint project of the GEWEX Global Land Atmosphere System Study (GLASS) and the CLIVAR Working Group on Seasonal-to-Interannual Prediction (WGSIP), provides a unique look at how land surface variables influence atmospheric processes in a number of atmospheric general circulation models (AGCMs). At present, a dozen AGCM groups have completed the same highly-controlled numerical experiments for GLACE, experiments specifically designed to quantify a model's land-atmosphere coupling strength. The general features of the coupling and the extent to which coupling strength varies among the participating GCMs are evaluated in this study. Analysis of the results shows that while the strength of land-atmosphere coupling varies widely across the models, certain commonalities are observed in the geographic pattern of coupling. It is found that the multi-model "hot spots" of coupling are generally located in the transition zones between wet and dry climates, where the evaporation is both sensitive to soil moisture and high enough to have an impact on rainfall. In some ways, this multi-model estimate of hot spots is the best such estimate attainable, given the sparseness of relevant observational data and the difficulties associated with interpreting such data. The inter-model differences in coupling strength are studied in terms of soil moisture's ability to affect evaporation and evaporation's ability to affect precipitation. We find that coupling strength tends to be highest in a given region for those models with both a high temporal evaporation variance and a strong control of soil moisture on evaporation.
B33A-0243 1340h
The Integrated Land Ecosystem - Atmosphere Processes Study (iLEAPS): A new Program to Study Land/Atmosphere Interactions in the Second Phase of IGBP
Recent progress in global change research has shown clearly that the Earth's environment is a complex system, defined through intricately linked processes, feedbacks and teleconnections. This integral perspective renders obsolete the conventional scientific approach of investigating disjunct causal relationships, and demands a new, integrated way of conducting environmental Earth research. To reflect this approach to Earth System Science, the new IGBP core project "Integrated Land Ecosystem - Atmosphere Processes Study" (iLEAPS) has been designed to study the interactions between land and atmosphere within the Earth System. The fundamental objective of iLEAPS is to provide understanding of how interacting physical, chemical, and biological processes transport and transform energy and matter through the land-atmosphere interface, particularly emphasizing interactions and feedbacks at all scales - from past to future and from local to global. The research planned for iLEAPS covers the basic processes that link surface-atmosphere exchange with vegetation/ecosystem processes on the one hand and with atmospheric dynamics, tropospheric chemistry and physical climate on the other. There will be four foci: 1) Land-atmosphere exchange of reactive and conservative compounds: Key interactions and feedbacks in the Earth System 2) Feedbacks between land biota, aerosols and atmospheric composition in the climate system. (a) Biosphere-aerosol-cloud-climate interactions, (b) Surface-atmosphere exchanges and the self-cleansing mechanism of the atmosphere 3) Feedbacks and teleconnections in the land surface -vegetation- water - atmosphere-system 4) Transfer of material and energy in the soil/canopy/boundary-layer system: Measurements and modelling
http://www.atm.helsinki.fi/ILEAPS/
B33A-0244 1340h
How strong is carbon cycle-climate feedback under global warming?
The behavior of the coupled carbon cycle and physical climate system in a global warming scenario is studied using an Earth system model including the atmosphere, land, ocean, and the carbon cycle embedded in these components. A fully coupled carbon-climate simulation and several sensitivity runs were conducted for the period of 1860-2100 with prescribed IPCC-SRES-A1B emission scenario. Results indicate a positive feedback to global warming from the interactive carbon cycle, with an additional increase of 90 ppmv in the atmospheric CO$_2$, and 0.6 degree additional warming, thus confirming recent results from the Hadley Centre and IPSL. However, the changes in various carbon pools are more modest, largely due to the multiple limiting factors constraining terrestrial productivity and carbon loss. The large differences among the three models are manifestations of some of the poorly constrained processes such as the global strength of the CO$_2$ fertilization effect and the turnover time and rates of soil decomposition.
B33A-0245 1340h
Examination of Terrain and Land use Control on Soil Water Chemistry in Two Suburban Watersheds
Scientific literature has advanced our understanding about controlling factors of water chemistry in forested watersheds, however the linkage between watershed characteristics and soil water chemistry in suburban watersheds is poorly understood. A better understanding of suburban watershed characteristics that control soil water chemistry concentrations will help watershed managers in addressing water pollution issue. Soil water samples were taken biweekly from nineteen sampling clusters throughout the study areas; B28 watershed, a 558860 m$^{2}$ catchment, and Power Station watershed, a 446450 m$^{2}$ catchment, in Croton New York City water supply system, from June 2001 to August 2002. Watershed characteristics (land use and topographic) were generated from land use data and 2 meters grided digital elevation model using extensive ARC/GIS functions and analyses. Clusters have a range of development density. Relationships between annual average total phosphorous (TP), total nitrogen (TN) and dissolved organic carbon (DOC) concentration and watershed characteristics were examined and regression models for TP, TN, and DOC concentration were developed. The best predictive model for average TP concentration was based on Number of houses and Road width (R$^{2}$ $_{adj}$ = 0.47), based predictive model for average TN concentration was based on number of houses and impervious area (R$^{2}$ $_{adj}$ = 0.78), and best predictive model for average DOC concentration based on road width (R$^{2}$ $_{adj}$ = 0.46).
B33A-0246 1340h
The Global Emissions Inventory Activity (GEIA) project of IGBP
The Global Emissions Inventory Activity (GEIA) was created in 1990 as an activity of the International Global Atmospheric Chemistry Project (IGAC) - a core project of IGBP. GEIA has been developing and distributing inventories of global gas and aerosol emissions from natural and anthropo-genic sources, The database has sufficient accuracy and spatial and temporal resolution to be currently widely used in global chemistry-transport models, and hence is considered as a standard for Earth sci-ence studies. The inventories provide a scientific foun-dation for assessments dealing with global pollution, global warming, stratospheric ozone depletion, acid precipitation and biological damage. In addition to the inventories, GEIA has summarized the state of the science for each inventory constituent. The list of species, data sets and their documentation, state of science summaries, workshop overviews, planning documents, and a list of the people involved can be obtained from www.geiacenter.org. As a result of the fast development of chemistry-trans-port models and Earth System models, and the large amount of new observational data becoming available, GEIA is entering a new phase. The main objective of GEIA is to "quantify the anthropogenic emissions and natural exchanges of trace gases and aerosols that drive Earth System changes". The poster will detail the different themes within GEIA, as well as the current and future activities, which are either related to integrated or international projects, or driven by scientific or societal issues.
B33A-0247 1340h
Dust Deposition, Ecosystem Response, and Oceanic Uptake of Atmospheric CO2
The transport of mineral dust from the continents to the oceans accounts for most inputs of the important micronutrient iron to surface waters. Increasing dust deposition can lead to increased biological production and export, directly, in the iron-limited High Nitrate, Low Chlorophyll (HNLC) regions, and indirectly by increasing rates of nitrogen fixation in tropical and subtropical regions where the community is often limited by nitrogen availability. Similarly, reductions in dust deposition can lead to reduced biological productivity through both of these pathways. Our global-scale, Biogeochemistry/Ecosystem/Circulation (BEC) model includes explicit representation of both pathways whereby dust deposition can influence ocean biogeochemical cycling. The BEC model includes explicit iron cycling and multiple phytoplankton functional groups, including the nitrogen fixers. We examine the ecosystem response to variations in dust deposition over interannual to decadal timescales. The BEC model will be used to quantify the shifts in phytoplankton production and community structure, global-scale patterns in nutrient limitation of phytoplankton growth rates, and surface ocean biogeochemical cycling. The sensitivity of air-sea carbon dioxide exchange over interannual to decadal timescales to variations in dust deposition will also be examined.
http://www.ess.uci.edu/~jkmoore.html
B33A-0248 1340h
Reconciling Top Down and Bottom Up Approaches to Understand Land Carbon Cycle Variability
Cycle Variability Two fundamentally different approaches for estimating global carbon sources and sinks have been used over the past 15 years. The so-called "Top-down" approach involves analysis of atmospheric composition and often includes inversions of atmospheric transport. Bottom-up approaches, on the other hand, involve using carbon cycle process models driven by various observational data. Reconciling the results of these two approaches can provide powerful constraints on each but is challenging because of the large uncertainties in atmospheric measurements and transport and in our understanding of the processes controlling biogeochemical cycling of carbon. Recently, the Atmospheric Carbon Inversion Intercomparison (TransCom 3) completed mean seasonal cycle and interannual variability inversions using 12 transport models. Their results include predictions of biogeochemically driven net carbon fluxes with associated uncertainties for the globe divided into 22 regions, half of which are land regions. The cyclo-stationary inversions predicted the mean seasonal cycle as well as the mean sink/source of each region. The interannual inversions predicted the interannual variability in the sources and sinks for each region between 1980 and 2000. This study describes an analysis of the processes controlling biogeochemically driven net carbon fluxes over the seasonal cycle for each of the Transcom land regions. The processes considered are those included in the CASA biogeochemical model. The seasonally variable model inputs include NDVI, temperature, precipitation and solar radiation and burned area. The contributions of NPP, heterotrophic respiration and fire season to the seasonal cycle are evaluated for each of the 11 TransCom 3 land regions. We prescribed plausible scenarios in the biogeochemical model to evaluate the mechanisms responsible for the size and seasonality of the mean annual carbon sinks reported by TransCom 3. Initial results will also be presented for a top-down/bottom-up analysis of interannual variability in land biogeochemical carbon fluxes.
B33A-0249 1340h
Analysis of the global distribution of water isotopes in the NCAR atmospheric general circulation model
The cycling of water isotopes has been incorporated into the NCAR atmospheric general circulation model, CAM2. Isotope dynamics follow that of Jouzel et al. (1987) and other GCMs, with fractionation associated with evaporation at the surface as well as with cloud processes. The model yields a reasonable global pattern of water isotopes in precipitation; e.g., the 18O decreases as temperature increases, and it also decreases as precipitation amount increases. The latitudinal and vertical distribution of 18O in the atmospheric vapor is caused by the ratio of the condensation rate to the amount of vapor, with greater depletion at high latitudes and high altitudes. Over the ocean, the balance between precipitation and evaporation determines the isotopic composition of precipitation, with 18O less depleted where evaporation minus precipitation is high. This explains the "amount effect" of water isotopes. The role of land evapo-transpiration on the isotopic composition of vapor and precipitation will be discussed.
B33A-0250 1340h
Atmospheric microbiology in coastal northern California during Asian dust events
Each year, billions of tons of dust are swept from deserts in China and Africa across the globe to the US and Caribbean. Microorganisms are likely hitchhikers aboard this aerosolized dust, with potential human health and ecological impacts. In order to investigate the presence of bacteria and fungi in dust storms from Asia, atmospheric samples for cultivatable microbiological analysis were collected during the NASA Extended- Modis Validation Experiment (EVE), occurring April 21-30, 2004 and coinciding with seasonal Asian dust storm activity. Samples were taken by Twin Otter aircraft along the coast of northern California ($\sim$100 km offshore of Monterey to San Francisco). An $\sim$100 km horizontal leg was flown at $\sim$100 km altitude, typically in the marine boundary layer, followed by a vertical spiral to the dust layer (as indicated by aerosol extinction monitoring) and a second horizontal leg in the dust layer at higher altitudes (2,100-4,200 m). Air samples were taken via Venturi tube inlets with sterile Millipore filter holders outfitted with 47 mm diameter test filters connected to a vacuum pump system. Total sample time varied and was based on flight conditions and EVE objectives. Typical flow rates were 40 lpm and average sample times were $\sim$1hr in the marine layer and $\sim$30 minutes in the dust layer. Control samples for handling and contamination were also obtained. Microbial culture of the filters was conducted using sterile techniques and R2A agar, with filters incubated in the dark at room temperature and monitored for growth over a 2-week period. Fungi and bacterial colonies were further isolated on fresh plates of R2A and Tryptic Soy Broth for the purpose of cataloging/storage. No isolates were obtained from samples of dust layers at altitude. This result may be explained by: i) inadequate sample volumes to detect extremely low bacterial numbers, though sample volumes ranged from 750-2100 liters, ii) light dust layer concentrations during the sampling period and/or iii) problems with the sampling protocol. The latter can be ruled out since isolates were obtained for marine boundary layer samples ($<$100 m). All controls were negative for growth. Bacterial and fungal isolates from the marine layer were identified via 16S and 18S rDNA sequencing and included fungi such as {\it Cladosporium cladosporioides}, a microbe routinely found in atmospheric samples, and bacteria such as {\it Bacillus mycoides}, a nitrogen fixer and common soil isolate.
B33A-0251 1340h
Understanding Long-Term Boreal Soil Carbon Accumulation: Insight from a Dynamic Layered Soil Model
Despite repeated fire disturbance, low-lying boreal forests have managed to accumulate large and globally significant stocks of C. Furthermore, boreal soils have historically occupied discontinuous and continuous permafrost zones and currently are experiencing a warming climate. Combined, these factors may result in loss of permafrost and increase in decomposition of the soil C. However, before attempting to assess the potential for future change in boreal soil C, the decadal to millennial mechanisms of soil C cycling and accumulation must be well understood. To that end, we developed a dynamic layered long-term soil C model to specifically address: 1) the influence of the soil thermal regime, 2) substrate recalcitrance through humification, and 3) the role of permafrost on the preservation and accumulation of boreal soil C. We included radiocarbon in our model so that we could compare soil C stocks as well as radiocarbon distribution to observations from a well studied Old Black Spruce (OBS) site in Manitoba, Canada. Using parameters from the literature, our results indicate that the accumulation of boreal soil C is dependent on the interaction between the soil thermal regime and humification. While these factors account for much of the soil C accumulation observed at OBS, the weighted average radiocarbon in the modeled deep soil was too new, suggesting a lack of preservation and accumulation of old soil C. However, upon inclusion of a permafrost layer for several centuries, not only the C accumulation and distribution between shallow and deep soil layers improved, but the weighted average radiocarbon markedly improved with respect to the OBS site. Our results suggest that: 1) in the absence of permafrost, deep soil C turnover time is on the order of 200-300 y rather than the previous estimates of up to and greater than 1000 y and 2) the legacy from recent shifts in boreal climate and permafrost must be considered when evaluating current observations.
B33A-0252 1340h
Tropical Systems Research at the Universtiy of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS)
The global significance of the tropics is unquestionable. The tropical seas are the engine of earth's atmosphere and hydrosphere; they are the locus of major biodiversity; and most of the world's five billion inhabitants live in the tropics. At the same time these environments strongly influence both social and economic activities in various ways. Yet, in many ways, understanding of tropical systems lags that of other regions. To meet this need, RSMAS is developing an expansion of its already substantial focus on tropical systems. From its beginnings in the 1940s, the School's focus on the tropics was a natural result of its location adjacent to the Tropical Atlantic. During the subsequent decades, research interests have broadened and include the coupling between the two halves: the tropics and extratropics. The Faculty's involvement with the tropics spread to the Pacific and Indian Oceans, the Red Sea and the Persian Gulf and beyond to higher latitudes. In the last five years, a majority of the Faculty have explored some aspect of the tropical hydrosphere, biosphere, atmosphere, or geosphere in this important region. At present, all divisions, themes, and centers are involved significantly in the tropics. Over the years, research approaches have evolved from exploration and description to analysis, numerical simulation and inter-disciplinary integration. Now the Faculty is faced with the challenge of further integrating our science and applying some of the results to societal problems. To address these challenges, the present research foci build on existing strengths and develop novel and integrated research and a new and challenging curriculum focused on scientific, societal and economic aspects of the global tropics. Existing strengths in air-sea interaction and ocean-atmosphere coupling provides the platform for an expanded research program on hurricanes, the roles of the tropics in the global climate system, and coastal ocean-atmosphere-land interactions. Here also is a special opportunity to direct the results of research to societal problems; such as, the impacts of climate change, hurricanes and other hazards. Similarly existing strengths in fisheries, coral reefs, and physical-ecological connectivity are the basis for developing new research initiatives to understand these systems and their resources so as to guide their protection and wise use.
http://www.rsmas.miami