GC33A-0935
Stratospheric Injection of Reflective Aerosols or Particles by Means of Aviation Fuel Additives.
Various suggestions have been made for stratospheric aerosols or particles to simulate the observed cooling effect of major volcanic eruptions. The best known is the detailed proposal of Paul Crutzen for sulphur dioxide. Also extensively discussed is diatomous earth, injected as individual diatoms. (Silica particles originating as marine shells.) This paper describes the selection and preliminary testing of chemicals that might be used as aviation fuel additives to distribute these two products, sulphur dioxide and micron sized silica particles, from a high flying commercial or military aircraft. The two chemicals tested are dimethyl sulphide to produce sulphur dioxide and tetra ethyl silicate to produce silica particles. In a closed glass jar both of these chemicals are indistinguishable from jet aviation fuel. Both are clear, colourless, oily liquids. Both dissolve in aviation fuel in any proportion. Solutions of each of these chemicals have been burned in a paraffin blowlamp as a simple simulation of a jet engine combustion chamber. Observation of the combustion suggests that the desired chemicals are produced and that the silica particles are of smoke or mist (micron) size. It is suggested that the solutions would probably have no detrimental effects on the fuel tanks, pipes, pumps or combustion chambers of the jet engine. This paper includes general facts about jet engines, aviation fuel, aircraft fuel systems and flight plans which may not be known to climate scientists. Also briefly considered are the health consequences of silica particles in the stratosphere. No tests have been done on a jet engine. Suggestions are made on the type of tests that would be needed by an organization having engine static test facilities.
GC33A-0936
Spectrally resolved fluxes and cloud radiative forcing from collocated AIRS and CERES measurements: derivation and application in climate studies
Spectrally resolved outgoing thermal-IR flux and cloud radiative forcing (CRF) have unique values in climate studies and evaluating climate model simulations. Here we describe an algorithm for deriving such spectral flux and spectral CRF through the entire thermal-IR spectrum from the collocated Atmospheric Infrared Sounder (AIRS) and the Clouds & the Earth's Radiant Energy System (CERES) measurements over the tropical oceans. Based on the predefined scene types in the CERES Single Satellite Footprint (SSF) dataset, spectrally-dependent angular distribution models are developed and used to estimate the spectral flux at each AIRS channel. A multivariate linear prediction scheme is then used to estimate spectral fluxes at frequencies not covered by the AIRS instrument. The whole algorithm is validated using synthetic spectra as well as the CERES OLR measurements. Next, we show their application in climate studies by examining variations of spectral fluxes and CRFs at different timescales and comparing with counterparts from the GFDL model simulation. By comparing the observed spectral fluxes and CRFs and simulated ones over the eight longwave bands used in the GFDL model, compensating errors in the simulated OLR (or the simulated CRF) from different absorption bands are revealed. Discrepancies between the simulated and observed spatial distributions and seasonal evolutions of the spectral fluxes are further discussed. The simulated fluxes in the water vapor rotational band and ν2 vibrational- rotational band are higher than the observed through the whole tropics, while the flux difference in the window regions is correlated with large-scale circulation features. The modeled seasonal cycles of spectral fluxes show distinctly difference from the observed ones, especially in the water vapor band and CO2 band. The observed and simulated interannual variation from 2003 to 2005 is examined and the implication for model improvement is further discussed.
GC33A-0937
Simulating the Effects of Climate and Land Use Change on Wetland Hydrology in coastal South Carolina, USA
Hydrology controls the majority of ecosystem functions and ecological services derived from wetlands; it is also the primary regulator of carbon dynamics, which is significant because wetlands contain 20-30%\ of the terrestrial carbon. Accordingly, the ability to simulate wetland hydrology is fundamental to assessing ecosystem responses to climate change and other anthropogenic disturbances. We present the application of MikeShe to an Atlantic coastal plain watershed with long-term gauging records from the Santee Experimental Forest. The simulation model was calibrated and validated against stream outflow and water table, and evaluated by the Pearson correlation coefficient (R), and the Nash and Sutcliffe model efficiency metric (E). The E (0.72 and 0.93 for daily and monthly outflows and 0.52 for water table in a 3 year period), R (0.80, 0.98 and 0.83) and slope for the regression (0.84, 1.03 and 1.02) of observations vs. simulations showed that MikeShe can perform reasonably well to estimate the overall hydrology of this low-relief watershed (WS80). The calibrated and validated model was then used for assessing the hydrologic response of the watershed to climate changes and land use change, from forest to agriculture. The effects of altered precipitation or temperature on stream outflow and groundwater table may be significant. A simulated 10%\ decrease in precipitation decreased stream outflow 20%\ and the mean water table depth 15%\ (11cm on average within the watershed); a simulated 10%\ increase in precipitation increased stream outflow by 10%\ and mean water table depth 12%\ (8cm). A 2°C increase in mean temperature decreased stream outflow by 7%\ and water table by 6 to 22%\ (8cm on average ); this effect was primarily attributable to an increase ET. Simulated land use change from forest to agriculture caused large changes in the hydrology of watershed WS80; stream outflow increased by 29% and the mean water table was raised by 8cm.
GC33A-0938
Does Aerosol Geoengineering the Earth's Climate Pass a Cost-Benefit Test?
Anthropogenic carbon dioxide (CO2) emissions are changing the Earth's climate with potentially dangerous consequences. Ratified international agreements call for a reduction of CO2 emissions to avoid dangerous anthropogenic interference with the climate system. Recent studies have, however, proposed an alternative strategy: to geoengineer Earth's climate by injecting aerosol precursors into the stratosphere. It is often claimed that aerosol geoengineering would provide net economic benefits because geoengineering requires far lower near-term investments compared to deep cuts in CO2 emissions. However, aerosol geoengineering projects can also cause nontrivial economic costs. This is because aerosol geoengineering hinges on successfully counterbalancing the forcing effects of CO2 emissions (which decay over centuries) with the forcing effects of aerosol emissions (which decay within years). A failure to maintain this delicate balance can lead to abrupt climatic changes, with potentially substantial economic damages. Deferring cuts in CO2 emissions in favor of aerosol geoengineering is hence a deeply uncertain gamble, as it requires so far unknown institutions to reliably control aerosol forcings over centuries. Here we use a simple economic model to evaluate potential costs and benefits of aerosol geoengineering for a wide range of the deeply uncertain parameters. We show that aerosol geoengineering projects may cause economic damages that can far exceed the benefits and may hence fail a cost-benefit test.
GC33A-0939
Potential Sources for Hypolimnetic Nutrients and Suspended Sediments in Southern Cayuga Lake, New York.
A routine survey of the seven largest Finger Lakes of central New York State revealed elevated concentrations of suspended sediment and soluble reactive phosphate in the hypolimnion (bottom waters) of Cayuga Lake. This observation is a concern because if these hypolimnetic nutrients are circulated to the epilimnion through natural processes such as wind-driven seiche activity and/or anthropogenic processes such as Cornell's Lake Source Cooling project, they could stimulate additional algal productivity and degrade Cayuga Lake as a source of drinking water. Here, we present the first of a two year study investigating potential sources for bottom water turbidity and nutrients. Surface, mid-depth (40m above the lake floor), and bottom water samples were taken at five sites following a mid-lake transect at the southern end of the lake. Samples were collected bi-monthly from May through September of 2007 and were analyzed in the laboratory for total phosphorous (TP), soluble reactive phosphate (SRP), dissolved silica (SRSi), nitrates, chlorophyll-a, total suspended sediment, and major ion concentrations following standard limnological techniques. A SBE-25 SeaLogger CTD profile of conductivity, depth, temperature, pH, dissolved oxygen, fluorescence and turbidity was also collected at these five sites, and two additional sites located near the mouth of two major streams (Taughannock and Salmon Creeks). Sites 2, B, and D revealed the thickest nepheloid layers, typically 20 m thick, and largest concentrations of bottom-water turbidity of 5 to 7 NTUs. In contrast, other sites located farther from these two tributaries or in shallower water revealed benthic turbidities of 1 to 2 NTUs. Total suspended sediment values were also high for the bottom waters of sites 2 and D. Turbidity increased after major wind events and minor rainstorms, however, lower rainfall in 2007 compare to previous years made it difficult to differentiate between fluvial and lake floor erosional events. The results suggest that these southern streams and/or winnowing of the nearshore sediments by wind- driven waves and currents may have a major influence on the lake floor turbidity. The bacterial decomposition of the algal biomass, indicated by an increase in SRP (up to 15 times surface concentrations) and dissolved silica with greater water depth suggests that biological contributions to the benthic nepheloid layer are important as well.
GC33A-0940
Time scale of iodine cycling in gas hydrate systems at active margins: implications for the organic carbon cycle
Marine gas hydrates in active margins constitute a large reservoir of organically derived carbon whose origin is, however, not well understood. Iodine is found at highly elevated levels in pore waters associated with gas hydrates, and can be used as tracer for the origin of methane, due to its strongly biophilic behavior and the presence of a long-lived cosmogenic isotope (129I; T1/2 = 15.7 My). We applied the iodine isotopic system to determine ages of organic sources for iodine in hydrate fields of the Pacific margin, such as Cascadia Margin, Nankai Trough, Peru Slope, and Costa Rica Margin. In all of the sites, iodine ages in excess of 30 Ma were found, demonstrating that a major part of the iodine is not derived from local sources. In most cases, the ages are also older than the subducting marine sediments, suggesting derivation from sources in the upper plate of the subduction zones. Isotope mixing diagrams demonstrate also the presence of one or more younger sources (< 10 Ma) at all of these margins. The complex fluid flows migrating through the wedge to pick up iodine released from organic matter can be considered as a sampling of sources with various ages. In contrast to the endmember ages, the mixed isotope signature in most of the samples should represent the averaged time since the burial of a suite of organic source materials. Using a compiled database of ~250 iodine dates, the age distribution summarizing all of the margins can be calculated by combining the age density normalized to the number of samples at each margin. The Gaussian fit to this distribution results in an age with highest probability of 30 Ma. We suggest that, on average, the iodine and associated organic carbon currently returning to the oceanic reservoir was buried in the marginal wedges ~30 My ago. Given the wide occurrence of hydrates at these margins, our results indicate that the forearc area serves as an important mechanism for organic carbon cycling operating at tectonic time scales.
GC33A-0941
Improved Monitoring of Inter-annual Temperature Variability Using AIRS/AMSU Observations
AIRS/AMSU was launched on EOS Aqua in May 2002 and started producing useful data in September 2002. EOS is primarily a mission for studying inter-annual variability of the Earth's surface and atmospheric geophysical parameters for the purpose of improving understanding of climate processes. Surface skin temperature and atmospheric temperature profiles are among many geophysical parameters derived from analysis of AIRS/AMSU observations. The Goddard DAAC had previously analyzed AIRS/AMSU observations starting from September 2002 using the AIRS Science Team Version 4 retrieval algorithm. The AIRS Science Team Version 5 retrieval algorithm became operational at the Goddard DAAC in July 2007 for use in processing AIRS/AMSU data subsequent to that time, and also for reprocessing all the old AIRS/AMSU data. Version 5 contains substantial improvements in capabilities compared to Version 4, especially with regard to improved spatial coverage of retrievals deemed acceptable for generation of climate data sets. These differences in methodology will be briefly described, and results will be shown demonstrating that inter-annual differences of surface and atmospheric temperatures obtained using the Version 5 algorithm are superior to those found in the previous AIRS data record obtained with the Version 4 algorithm.
GC33A-0942
Online Impact Prioritization of Essential Climate Variables on Climate Change
The National Oceanic & Atmospheric Administration (NOAA)'s NCDC Scientific Data Stewardship (SDS) Team has developed an online prototype that is capable of displaying the "big picture" perspective of all Essential Climate Variable (ECV) impacts on society and value to the IPCC. This prototype ECV-Model provides the ability to visualize global ECV information with options to drill down in great detail. It offers a quantifiable prioritization of ECV impacts that potentially may significantly enhance collaboration with respect to dealing effectively with climate change. The ECV-Model prototype assures anonymity and provides an online input mechanism for subject matter experts and decision makers to access, review and submit: (1) ranking of ECV"s, (2) new ECV's and associated impact categories and (3) feedback about ECV"s, satellites, etc. Input and feedback are vetted by experts before changes or additions are implemented online. The SDS prototype also provides an intuitive one-stop web site that displays past, current and planned launches of satellites; and general as well as detailed information in conjunction with imagery. NCDC's version 1.0 release will be available to the public and provide an easy "at-a-glance" interface to rapidly identify gaps and overlaps of satellites and associated instruments monitoring climate change ECV's. The SDS version 1.1 will enhance depiction of gaps and overlaps with instruments associated with In-Situ and Satellites related to ECVs. NOAA's SDS model empowers decision makers and the scientific community to rapidly identify weaknesses and strengths in monitoring climate change ECV's and potentially significantly enhance collaboration.
GC33A-0943
Bridging Scales: Developing a Framework to Build a City-Scale Environmental Scenario for Japanese Municipalities
There is an ongoing project on establishing environmental scenarios in Japan to evaluate middle to long-term environmental policy and technology options toward low carbon society. In this project, the time horizon of the scenarios is set for 2050 on the ground that a large part of social infrastructure in Japan is likely to be renovated by that time, and cities are supposed to play important roles in building low carbon society in Japan. This belief is held because cities or local governments could implement various policies and programs, such as land use planning and promotion of new technologies with low GHG emissions, which produce an effect in an ununiform manner, taking local socio-economic conditions into account, while higher governments, either national or prefectural, could impose environmental tax on electricity and gas to alleviate ongoing GHG emissions, which uniformly covers their jurisdictions. In order for local governments to devise and implement concrete administrative actions equipped with rational policies and technologies, referring the environmental scenarios developed for the entire nation, we need to localize the national scenarios, both in terms of spatial and temporal extent, so that they could better reflect local socio-economic and institutional conditions. In localizing the national scenarios, the participation of stakeholders is significant because they play major roles in shaping future society. Stakeholder participation in the localization process would bring both creative and realistic inputs on how future unfolds on a city scale. In this research, 1) we reviewed recent efforts on international and domestic scenario development to set a practical time horizon for a city-scale environmental scenario, which would lead to concrete environmental policies and programs, 2) designed a participatory scenario development/localization process, drawing on the framework of the gStory-and-Simulationh or SAS approach, which Alcamo(2001) proposed, and 3) started implementing it to the city of Kawasaki, Kanagawa, Japan, in cooperation with municipal officials and stakeholders. The participatory process is to develop city-scale environmental scenarios toward low carbon society, referring international and domestic environmental scenarios. Though the scenario development is still in process, it has already brought practical knowledge about and experience on how to bridge scenarios developed for different temporal and spatial scales.
GC33A-0944
Radiation Exchanges at the Atmosphere-Vegetation Canopy Boundary Layer Based on Unmanned Aerial Vehicle Observations
Radiation exchanges at the vegetation boundary layer, regulating the amount of energy received by the vegetation canopy are examined through remote sensing observations carried out by an unmanned helicopter, flying according to pre-programmed plans, above a forested area. Information obtained from the laser scanning system, radiometric measurements and aerial photographs are combined to ambient meteorological parameters in order to examine interactions between leaf characteristics, elements of vegetation structure, and the surrounding atmosphere. A vegetation mass transfer model showing variable dependencies of leaf water content, leaf temperature, leaf-air vapor-pressure differences and solar radiation intensity as well as canopy structure is used to discuss transpiration mechanisms of the studied forest.
GC33A-0945
Towards Measures to Establish the Relevance of Climate Model Output for Decision Support
How exactly can decision-support and policy making benefit from the use of multiple climate model experiments in terms of coping with the uncertainties on climate change projections? Climate modelling faces challenges beyond those of weather forecasting or even seasonal forecasting, as with climate we are now (and will probably always be) required to extrapolate to regimes in which we have no relevant forecast-verification archive. This suggests a very different approach from traditional methods of mixing models and skill based weighting to gain profitable probabilistic information when a large forecast-verification archive is in hand. In the case of climate, it may prove more rational to search for agreement between our models (in distribution), the aim being to determine the space and timescales on which, given our current understanding, the details of the simulation models are unimportant. This suggestion and others from Smith (2002, Proc. National Acad. Sci. USA 4 (99): 2487-2492) are interpreted in the light of recent advances. Climate models are large nonlinear dynamical systems which insightfully but imperfectly reflect the evolving weather patterns of the Earth. Their use in policy making and decision support assumes both that they contain sufficient information regarding reality to inform the decision, and that this information can be effectively communicated to the decision makers. There is nothing unique about climate modeling and these constraints, they apply in all cases where scientific modeling is applied to real-word actions (other than, perhaps, the action of improving our models). Starting with the issue of communication, figures from the 2007 IPCC Summary for Policy Makers will be constructively criticized from the perspective of decision makers, specifically those of the energy sector and the insurance/reinsurance sector. More information on basic questions of reliability and robustness would be of significant value when determining how heavily to weight climate model output in the decision process; one obvious example is the question of over what spatial and time averages modelers expect information in current climate distributions to be robust. The IPCC itself suggests continental/seasonal, while distributions over 10's of kilometers/hourly is on offer. Our aim here is not to resolve this discrepancy, but to develop methods with which it can be addressed. This is illustrated in the context of using another physically based, imperfect model setting: using Newton's laws in an actual case of NASA hazard evaluation. Our aim is to develop transparent standards of good practice managing expectations, which will allow model improvements over the next decades to be seen as progress by the users of climate science. http://www.lse.ac.uk/collections/cats/
GC33A-0946
Examining the potential impact of a warming ocean on food insecure Africa: concerns and mechanisms for abrupt climate change
Given that more than 200 million sub-Saharan Africans are food insecure, abrupt climate change in Africa could be devastating. Recent observations for eastern and southern Africa suggest substantial declines in main growing season rainfall over the past 20 years. In this talk we present research from a multi-year study that examined the causes and implications of these drying trends. Our statistical and dynamic modeling results suggest that warming in the Indian Ocean has been linked to increased oceanic convection and disruptions in onshore moisture transports. These moisture transport disruptions, in turn, are probably associated with an increased frequency in agricultural drought in sub-tropical countries along Africa's eastern seaboard. This 'warm ocean-dry Africa' dipole appears to be a major driver of decadal variability. An evaluation of 11 climate change models suggests that increased tropical Indian Ocean precipitation, and the associated moisture transport disruptions, may in fact be anthropogenic, accounting for at least part of the regional drought tendencies in eastern and southern Africa over the past 20 years. These simulations also suggest continued increases in oceanic convection will be very likely over the next century. This diabatic forcing will likely produce continuing rainfall declines across 7 food insecure nations. These drying trends, combined with declining per capita agricultural capacity, are likely to contribute to a ~250 percent increase in food shortages over the next 30 years. Modest agricultural and market development, however, could alleviate the food problem substantially.
GC33A-0947
Climate Change Database Development and Learning Networks Establishment
The Nature Conservancy is developing a comprehensive database that includes the most relevant climate change data for its conservation practitioners. The database is developed in close collaboration with the field. Data mining tools and web base interface are refined to simplify the acquisition and analysis of the relevant information such as future climate change scenarios. Significant challenges arise when local strategies to address climate change issues require land managers to develop new strategies to manage preserves or purchase properties. The resolution of future climate projections are usually too coarse and too uncertain to be considered as useful by practical land stewards. The Conservancy Climate Change Science Team is working in collaboration with government agencies, academia and other NGOs to quantify the uncertainty and package climate change information to help on the ground actions around the world. The team is also developing a climate change learning network to bridge the gap between scientific knowledge and on the ground expertise.
GC33A-0948
Effects of dust in hyperspectral sounder data and impact on OLR
The thermal infrared radiances measured at the top of the atmosphere (TOA) by high spectral resolution sounding instruments are significantly affected by large particle mineral aerosols (desert dust) and cirrus. Since September 2002, NASA's AIRS instrument has provided us with very stable high quality data that can be used to detect and monitor dust events and cirrus cloud cover. Here we will present global estimates of desert dust optical depths, as well as lower bound estimates of Outgoing Longwave Radiation forcing due to dust, using four years of AIRS cloud cleared radiances and radiances that have passed through an uniform-clear filter.
GC33A-0949
Seasonal Modulation of Atmospheric Parameters From AIRS and Correlations With the GISS and CCSM Climate Models
The first five years of data from the Atmospheric Infrared Sounder (AIRS) show very consistent seasonal modulations of key surface, cloud, and atmospheric temperatures and water vapor, which give a unique insight into the way the Earth Climate System responds to periodic forcing with changes in surface and atmospheric temperatures. We characterize this seasonal modulation by its mean, it peak-to-peak amplitude and its phase relative to the top-of-atmosphere incident shortwave solar radiation. The comparison of equivalent parameters from the NASA/GISS and the NCAR/CCSM climate models show high correlation between the two models, but relatively poor correlation with the AIRS observations, except for the annual mean, amplitude modulation and phase of the sea surface temperature. The phase shift between the driving force (the solar incident radiation) and the response of the atmosphere is the key parameter in the evaluation of feedback. A phase shift difference in key atmospheric and cloud related parameters of more than one month between the AIRS observations and the climate models suggest that the clouds and water vapor processes implemented in both models are inadequate.
GC33A-0950
Molybdenum isotope signatures from the Yangtze block continental margin and its indication to organic burial rate
Abstract The paper presents the molybdenum isotope data, along with the trace element content, to investigate the geochemical behavior of authigenic Mo during long-term burial in sediments in continental margin settings of the Yangtze block, as well as their indication to the burial of original organic carbon. The burial rate of original organic carbon were estimated on the basis of the amount of sedimentary sulfur (TS content), whilst the carbon loss by aerobic degradation was estimated according to calculated Mn contents. On these points, the original organic carbon flux was calculated, exhibiting a large range of variation (2.54-15.82 mmol/m2/day). The strong correlation between sedimentary Mo isotope values and organic carbon burial rates previously proposed on the basis of the investigations on modern ocean sediments was also used here to estimate the organic carbon burial rate. The data gained through this model showed that organic carbon burial rates have large variations, ranging from 0.43- 2.87mmol/m2/day. Although the two sets of data gained through different geochemical records in the Yangtze block show a deviation of one order of magnitude, they do display a strong correlation. It is thus tempting to speculate that the Mo isotope signature of sediments may serve as a tracer for the accumulation rate of original organic carbon in the continental margin sediments. Keywords: Molybdenum isotopes; organic carbon burial rate; ancient continental margin setting ACKNOWLEDGMENTS We thank Professor Xie Shucheng for his constructive review comments. This research is co-supported by the Program for Changjiang Scholars and Innovative Research Team in University (grants IRT0441), the SinoPec project (grant no. G0800-06-ZS-319) and the National Nature Science Foundation of China (grants 40673020).
GC33A-0951
Monitoring: a vital component of science at USGS WEBB sites
The U.S. Geological Survey launched its Water, Energy, and Biogeochemical Budgets (WEBB) program in 1991 with the establishment of five long-term research watersheds. Monitoring of climate, hydrology, and chemistry is the cornerstone of WEBB scientific investigations. At Loch Vale, CO, long-term streamflow and climate monitoring indicated an increase rather than the expected decrease in the runoff:precipitation ratio during a drought in the early 2000s, indicating the melting of subsurface and glacial ice in the basin. At Luquillo Experimental Forest in Puerto Rico, monitoring of mercury in precipitation revealed the highest recorded mercury wet deposition rates in the USA, an unexpected finding given the lack of point sources. At Panola Mountain, GA, long-term monitoring of soil- and groundwater revealed step shifts in chemical compositions in response to wet and drought cycles, causing a corresponding shift in stream chemistry. At Sleepers River, VT, WEBB funding has extended a long- term (since 1960) weekly snow water equivalent dataset which is a valuable integrating signal of regional climate trends. At Trout Lake, WI, long-term monitoring of lakes, ground-water levels, streamflow and subsurface water chemistry has generated a rich dataset for calibrating a watershed model, and allowed for efficient design of an automated procedure for sampling mercury during runoff events. The 17-plus years of monitoring at the WEBB watersheds provides a foundation for generating new scientific hypotheses, a basis for trend detection, and context for anomalous observations that often drive new research.
GC33A-0952
Impact of geo-engineered aerosols on stratospheric composition and dynamics
A recently proposed geo-engineering scheme to limit greenhouse warming is the injection of sulfur into the stratosphere to increase the Earth's albedo. This is expected to reduce tropospheric temperatures, as observed following large volcanic eruptions (for example, Mt. Pinatubo in June of 1991). However, that eruption also enhanced stratospheric ozone loss in the Arctic lower stratosphere via heterogeneous processes on sulfate aerosols. The impact of artificially enhancing the sulfate layer on chemical ozone loss can be estimated roughly for future chlorine conditions in the stratosphere. However, such estimates do not predict radiative effects, or the entire range of changes in stratospheric composition, dynamics and temperature. Here, we present first results of a transient climate simulation with enhanced anthropogenic sulfate aerosols using a 3D coupled Chemistry Climate Model, the Whole Atmosphere Community Climate Model (WACCM). In contrast to previous model studies, the impacts on stratospheric chemistry, including heterogeneous chemistry in the polar region are considered in this simulation. Changes in chemistry also affect the radiation budget and feed back on atmospheric transport. Further, interactions between atmospheric and ocean temperatures are included in this simulation, which includes a coupled slab ocean model. We assume a stratospheric distribution of volcanic-like liquid sulfate aerosols consistent with the injection of 2 Tg S/year, as calculated by the NCAR Community Atmosphere Model (CAM3). Using WACCM, we expect significant changes in composition, especially ozone depletion in the Northern Hemisphere for cold Arctic winters, and corresponding changes in dynamics and temperatures in the stratosphere and troposphere.
GC33A-0953
Exploring the Link Between Streamflow Trends and Climate Change in Indiana, USA
Streamflow trends in Indiana are evaluated for 85 USGS streamflow gaging stations that have continuous unregulated streamflow records varying from 10 to 80 years. The trends are analyzed by using the non-parametric Mann-Kendall test with prior trend-free pre-whitening to remove serial correlation in the data. Bootstrap method is used to establish field significance of the results. Trends are computed for 12 streamflow statistics to include low-, medium- (median and mean flow), and high-flow conditions on annual and seasonal time step. The analysis is done for six study periods, ranging from 10 years to more than 65 years, all ending in 2003. The trends in annual average streamflow, for 50 years study period, are compared with annual average precipitation trends from 14 National Climatic Data Center (NCDC) stations in Indiana, that have 50 years of continuous daily record. The results show field significant positive trends in annual low and medium streamflow statistics at majority of gaging stations for study periods that include 40 or more years of records. In seasonal analysis, all flow statistics in summer and fall (low flow seasons), and only low flow statistics in winter and spring (high flow seasons) are showing positive trends. No field significant trends in annual and seasonal flow statistics are observed for study periods that include 25 or fewer years of records, except for northern Indiana where localized negative trends are observed in 10 and 15 years study periods. Further, stream flow trends are found to be highly correlated with precipitation trends on annual time step. No apparent climate change signal is observed in Indiana stream flow records.
GC33A-0954
A new method for biometrically-based estimation of pre-settlement forest carbon stocks in the United States
I present a new method to provide a historical baseline estimate of pre-settlement (19th century) forest carbon stocks over much of the United States. Land use changes are important drivers of land-atmosphere carbon dynamics. In the United States, quantification of terrestrial carbon loss due to alterations of pre-settlement forests has been very imprecise, because the only data set suitable for the purpose, the General Land Office (GLO) bearing tree data, was collected for non-ecological purposes. However, one crucial parameter necessary for the estimation of tree density was not collected. Fortunately, other information from which that parameter can be estimated, was collected. Tee size data was also collected, so that once the missing parameter is estimated, tree density and size data allows for the estimation of derivative variables such as tree height, biomass, and carbon, using allometric equations. The missing parameter is the rank order of the distance of sampled trees from nearby survey points. The method is based on spatial simulations of tree locations and survey points, and a numerical, maximum-likelihood based estimation procedure. The only simplifying assumption required is that trees are more or less randomly arranged around each sample point. Tree patterns at larger spatial scales can vary from random to highly aggregated. Estimation of density relies on a robust formula applicable to either random or non-random spatial patterns, as developed by Morisita in 1957. Estimation of the ranked distances involves the comparative analysis of 15 independent statistics based on the ratios of distances of pairs of trees from survey points. The tree pairs can take on rank order values of up to 20, creating 190 independent distributions for each statistic. The same statistics computed from actual GLO data are then compared to the distributions from the simulated data, using a type of maximum likelihood estimation, to estimate the ranked distance for both trees in each pair. The accuracy and precision of density estimates based on the univariate and multivariate distributions of the various statistics is explored via further simultation.
GC33A-0955
Erosion of the Barrow Environmental Observatory Coastline 2003-2008, Northern Alaska
There is concern that the rate of erosion to Coastal bluffs in the arctic could increase as the duration of ice-free near shore waters also increases. The Barrow Environmental Observatory (BEO,) a coastal research reserve of 7500 acres is bounded on the east by the 11-km long Elson Lagoon shoreline. Rates of erosion to these 2 to 5 m high ice- and organic- rich permafrost bluffs have been monitored at key sites on an annual basis since 2003 as part of the Arctic Coastal Dynamics (ACD) program. Foot surveys using a survey-grade Differential Global Positioning System (DPGS) with centimeter vertical and horizontal accuracy were conducted along the entire length of the BEO coastline in August 2003, 2006 and 2007. The mean erosion rate during the 2003-06 period was 2.69 meters per year. In summer 2007, two DGPS surveys were conducted, one in June before ice breakup and the second in August late in the summer season. The June survey provides a baseline for summer 2007 measurements and will serve to document the rate of erosion between the August 2006 survey and subsequent freeze-up of Elson lagoon during the 2006-07 winter. Detailed characterization of the coastal bluff was also made in summer 2007. At every 100m along the coastal bluff, photographs of the bluff were taken and the steepness of the bluff was measured. Bathymetric measurements were collected using a high-velocity depth sounder along transects parallel and perpendicular to the coastline and up to 2km in to Elson Lagoon. Ongoing analysis is measuring the rate of erosion between each of the measurement periods and estimating the corresponding volumetric loss of bluff soil to Elson Lagoon. We are also identifying in detail, sections of coastline where the rate of erosion is differing and using these to ascertain the relative importance of offshore bathymetry, orientation of the coastline to dominant winds and the physical characteristics of the coastal bluff to the rate of erosion measured. The central goal of this paper is to report and interpret changes in inter-seasonal erosion and to update the record of long-tern erosion measurements for this section of arctic coastline.
GC33A-0956
Data Integration for Spatiotemporal Imaging
The primary objective of this study is the development of data evolution methods that integrate previously acquired data with newly acquired data for use in 4-D dynamic tomography. Applications include monitoring of subsurface aquifers, petroleum reservoir, and sequestered carbon dioxide migration in geologic reservoirs. In carrying out a time lapse monitoring experiment, two scenarios are possible: acquiring complete datasets at very large time steps or acquiring incomplete (sparse) datasets at closely spaced time steps. The latter scenario gives the opportunity for tracking changes in the reservoir more frequently and is therefore, preferred. However, the data acquisition process for this latter scenario must trade off spatial resolution for temporal resolution. With the standard methods used today, every dataset is inverted independently. Upon the application of a data evolution method, spatial resolution can be improved while maintaining high temporal resolution. The underlying premise for which the presented methods are developed is that throughout the lifetime of the reservoir being monitored, a few sources and receivers can be used to acquire quasi-continuous data. A complete dataset may have been acquired during site characterization and can be used as the "base" dataset. It can be as high as 10 to 20 times the size of a sparse dataset. Given that the dataset are sparse, one potential quandary is the development of an under-determined tomographic inversion problem, in which case, there is less data than the number of unknowns. The methods presented in this paper address this problem as well.
GC33A-0957
Climate-Vegetation-Feedbacks as a Mechanism for Accelerated Climate Change: The Greening Sahara Case
In a set of experiments with global atmosphere-ocean-vegetation models, we analyze the terrestrial vegetation history from the Last Glacial Maximum to the pre-industrial time. In this presentation we explore the mechanisms in the coupled atmosphere-ocean-vegetation system that initiate the migration of the African Monsoon rainfall into the Sahara and the subsequent greening of the Sahara. It is found that the vegetation-albedo-feedback is of crucial importance for the northward extension of the vegetation zone into the Sahara desert. This feedback leads to an amplified response of the African Monsoon to the orbital forcing in the early Holocene. We further discuss the changes in the terrestrial carbon storage and its implications for atmospheric CO2 concentrations. A preliminary comparison between model results and paleoproxy records is presented.
GC33A-0958
AIRS Science Data Services at NASA Goddard Earth Sciences Data and Info Services
The Atmospheric Infrared Sounder (AIRS) is a very high spectral resolution passive infrared sounder with more than 2000 well-calibrated spectral channels measuring in the range of 3.74 - 15.4 micron. The AIRS instrument was successfully launched aboard the NASA Aqua spacecraft in May, 2002 and has been providing global coverage ever since. The infrared radiance data product is stable to 10 mK/year and accurate to better than 250 mK. The AIRS product is the most accurate and stable set of hyperspectral infrared radiance spectra measurements made in space to date, and its meets the criteria identified by the National Research Council for climate data records. In addition, working in tandem with an Advanced Microwave Sounding Unit (AMSU-A) instrument, AIRS provides a three-dimensional view of the geophysical properties of the Earth's atmosphere. The geophysical products provide daily global temperature profiles at an accuracy of 1 K per 1 km thick layer in the troposphere and moisture profiles at an accuracy of 20% per 2 km thick layer in the lower troposphere (20% - 60% in the upper troposphere). AIRS standard swath and grid data products are available from the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). The latest version of AIRS products (Version 5) has many improvements over previous versions including better temperature and water vapor profiles, enhanced Level 2 temperature data products over land and polar regions, first-time retrievals of carbon monoxide and methane, improvements to ozone retrievals, warning 'flags' to identify concentrations of sulfur dioxide and dust and overall improvements error and quality flag parameterization. In addition to the AIRS standard products, the swath-based AIRS products are also produced in near real time (NRT) at the GES DISC facility using the same core science algorithms as in the regular science data production but using predicted ephemeris in place of definitive ephemeris data. Approximately 80% of AIRS NRT calibrated radiance products are available to the public within 2 hours after the time of observation, 3 hours for 80% of the NRT retrieval products. The AIRS NRT products are useful for those who need data low data latency; they have been utilized in regional weather forecast models as well as in support of regional field experiments. The GES DISC provides a range of value-added services in support of the AIRS user community. Generally, these services can be grouped into data search, access and retrieval, subsetting and format conversion, online data visualization and analysis. Highlights of some of these services include binned Level 2 data for precipitation studies, subsets by channel, parameter or spatial area, data visualization through the Giovanni tool, conversion to netCDF format, Web Map Services and access through OPeNDAP. http://disc.sci.gsfc.nasa.gov/AIRS/
GC33A-0959
Screening Level Analysis of Several Geo-engineering Techniques Intended to Mitigate Global Warming
Within the past few years, a number of papers have appeared in the literature that describe alternative geo- engineering techniques that could be used to supplement more mainstream options to mitigate global warming. An example of a mainstream option is carbon capture and storage, and an example of a geo-engineering approach is an orbiting satellite that provides a sun-shade to earth. These supplemental geo-engineering techniques, which are controversial for reasons such as they appear to allow emissions of carbon to continue unabated, are really intended to bridge the time gap between where we are today and where we need to be in terms of the implementation of mainstream mitigation schemes. Allowing that geo-engineering techniques are controversial, and could cause more harm than good, there are still reasons to examine them. As an example, would it be possible to "uncommitt" from projected sea level rise that already threatens low-lying countries by reducing incoming solar radiation? For this poster, then, several alternative geo-engineering techniques (which can broadly be classified as space-based and earth-based) will be examined. A screening level global equilibrium radiation model will be used to examine the global temperature response to various alternatives, implemented at scales proposed by their developers. The equilibrium model will provide an estimate of global temperature change once the perturbed energy fluxes have returned to a balanced state. Thus the time frame of radiation adjustment will not be evaluated. Further, since we know that greenhouse gas emissions will likely continue to increase for decades into the future, the efficacy of any geo-engineering scheme could diminish over time unless appropriate modifications to the operation of those schemes are made. This aspect of time evolution of geo-engineering will also be discussed. Finally, since there does not appear to be a "silver bullet" solution to climate change, either from mainstream approaches or otherwise, a brief analysis will be provided of the feasibility of more than one geo-engineering scheme becoming operational simultaneously, or nearly so.
GC33A-0960
The Sensitivity of Coastal Cliffs to Changes in Sea Level
The impact of waves upon coastal cliffs is a significant control on erosion and subsequent cliff retreat. It is widely anticipated that climatically-driven sea-level rise will result in an increase in the rate of erosion, and thus the retreat, of coastal cliffs. Quantifying the changes in the rate of coastal erosion remains problematic, primarily due to the difficulty of collecting high-precision and high-frequency monitoring data on both cliff change and the variations in environmental conditions at the coast. In the UK, local authorities now have to produce a "Shoreline Management Plan" (SMP), indicating how the coastline will be managed for the future. This requires the estimation of rates of coastal retreat over the next century, making the impact of sea-level change a critical consideration. This study presents the results from a three year monitoring survey of a section of near-vertical coastal cliffs in north-east England. Data have been collected using a high-resolution terrestrial laser scanner to obtain cliff surfaces. Analysis of successive 3D cliff models is used to derive sequential change, from which the precise nature, geometry and rate of retreat can be measured. In parallel, data has been collected on the micro-seismic impact of waves onto the cliff to gain a direct measure of the delivery of energy at any given sea-level, rather than using a function of wave and tide gauge records. The coastline studied has a significant tidal range, in excess of 6 m, in addition to a large seasonal variability in mean tide heights, allowing a range of sea-level conditions to be assessed. For comparison weather, tide and wave monitoring has been undertaken. The results suggest a close link between the magnitude and frequency of wave impact and the loss of material from the cliff face. Marked changes in wave impact are apparent as the tide level fluctuates on an inter-monthly and inter-annual basis. Thresholds are identified which appear to reflect discrete changes in wave energy delivery as tidal level rises, possibly reflecting critical inundation depths and wave propagation up onto the cliff face. The cliff monitoring data show a similar sensitivity with a marked increase in absolute volumes of material loss, the location of these losses on the cliff face and the resulting effective rate of cliff face retreat. The results demonstrate the sensitivity of the cliffs and the short term variability in response. The study provides significant insights into both the likely future retreat of cliffs in response to climate change and perhaps more importantly the nature with which cliffs accommodate and respond to sea-level changes.
GC33A-0961
Hydrology and Ecology of the Colorado River Delta in the Face of Changing Climate and Land Use Practices: the Next Fifty Years
The Lower Colorado River Delta in the U.S. and Mexico is an internationally important aquatic biome, supporting fresh water and estuarine wetlands and a riparian corridor rich in avian and other wildlife. These rich ecosystems could be severely harmed by invasive species interacting with projected climate change and land use practices over the next 50 years. It is critical to measure land cover and monitor ecosystem and land use changes because these ecosystems are supported by fresh and brackish water flows originating from flood control releases and agricultural return flows in the U.S. and Mexico. Most climate models project a drying trend in the Colorado River watershed due to global warming, decreasing the frequency of flood releases to the Delta. Total basin water storage in the reservoir system is expected to be reduced by 32-40 percent, and flow volume is expected to meet demands in only 59-75 percent of years in 50 years. The frequency of spills (years in which water is released from the reservoirs to the Delta) will decrease under a global warming scenario. However, the Pacific Decadal Oscillation and ENSO events will continue to introduce variability into river flows, and there will still be years in which water is spilled to the Delta. Agricultural return flows will decrease as more water is diverted from agriculture to metropolitan use in both countries. The salinity of the ground water in Mexico, which currently supports cottonwood and willow trees in the riparian corridor, is increasing at a rate of about 20 ppm per year, and in 50 years it might be too saline for cottonwoods and willows. The riparian zone may become dominated by saltcedar and other salt-tolerant shrubs, degrading the habitat for birds and other wildlife. As flows to the Delta diminish, monitoring and active restoration projects to maintain trees and wetlands will be needed to preserve habitat value.
GC33A-0962
Digital Mapping of Coastal Erosion on the Baldwin Peninsula, NW Alaska: Past Rates, Present Processes and Future Implications
As Arctic temperatures warm and increase the period of ice-free seas, coasts are exposed to longer periods of wave-based erosion. In addition, warming accelerates permafrost degradation and thus decreases the mechanical stability of coastal bluffs. In this study we examine the Baldwin Peninsula which extends 108 km northwest into Kotzebue Sound but narrows to a neck less than 700 meters wide at its midpoint. Currently, water discharge and fish runs from Selawik and Kobuk Rivers are routed around the northern tip of the peninsula, adjacent to where the Noatak River enters the sea. The eventual breach of the narrowest part of the peninsula will result in drastic changes in fish passage, the morphology of the Noatak River delta and local economies dependent on subsistence and commercial fishing. To constrain past and present rates of bluff erosion, we completed a high resolution (~3 m spacing) topographic survey along ~5 km of the narrowest segment of the Baldwin Peninsula. The total station survey (georeferenced using GPS measurements at stations) defined the current bluff edge position on both the seaward and estuary side of the peninsula. In addition, the position of the bluff base was collected on the seaward side. Bluff retreat is accomplished by failure of adjoining arcuate-shaped thermal slumps. Seasonal wave erosion at the base of the bluff prevents slumps from ever stabilizing. To determine historical rates of retreat, we used geo-referenced historical aerial photographs from 1953 to the present processed in ArcGIS. Future surveys will determine if retreat is accelerating or maintaining current rates and identify if certain portions are retreating faster than others or if retreat is even along the coast.
GC33A-0963
Smoothing climate time-series with information theory
The information theoretic approach to smoothing non-stationary time-series is presented incorporating B-splines with natural boundary conditions. This approach is applied to instrumental Northern Hemisphere annual mean time-series. In contrast to previous studies, the information theoretic approach provides rigorous objective criteria for choosing the model order and regularization parameter for optimal smoothing of climate time-series.