Sample records for early terrestrial atmosphere

  1. The persistent and pernicious myth of the early CO2-N2 atmospheres of terrestrial planets

    NASA Astrophysics Data System (ADS)

    Shaw, G. H.

    2009-12-01

    The accepted model for early atmospheres of terrestrial planets has settled on a CO2-N2 composition. Unfortunately, while it is largely based on a brilliant geological analysis by Rubey, there is no compelling evidence whatsoever for such a composition as the first “permanent” atmosphere for Earth or any other planet. In fact, geological discoveries of the past 50+ years reveal several problems with a CO2-N2 atmosphere, some of which Rubey recognized in his own analysis. He clearly addressed the problem of timing of degassing, concluding that early massive degassing of CO2 would produce readily observed and profound effects, which are not evident. Modeling and constraints on the timing of planetary accretion and core formation indicate massive early degassing. If early degassing emitted CO2-N2, the effects are concealed. Plate tectonic recycling is not a solution, as conditions would have persisted beyond the time of the earliest rocks, which do not show the effects. Attempts to return degassed CO2 to the mantle are not only ad hoc, but inconsistent with early thermal structure of the Earth. Second, production of prebiotic organic compounds from a CO2-N2 atmosphere has been a nagging problem. At best this has been addressed by invoking hydrogen production from the mantle to provide reducing capacity. While hydrogen may be emitted in volcanic eruptions, it is exceedingly difficult to imagine this process generating enough organics to yield high concentrations in a global ocean. The recent fashion of invoking organic synthesis at deep-sea vents suffers from the same problem: how to achieve sufficient concentrations of organics in a global ocean by abiotic synthesis when hydrothermal activity stirs the solution and carries the prebiotic products off to great dilution? Suggesting life began at deep-sea vents, and continues to carry on chemosynthesis there, begs the question. Unless you get high enough concentrations of prebiotics by abiotic processes, you simply don’t get life. Third, solutions invoking high atmospheric CO2 as the answer to the faint young sun problem encounter exactly the same problems associated with prompt degassing of CO2. Fourth, the carbon isotope record, in which early carbonaceous deposits show signs of photosynthetic fractionation of carbon are problematical if most of the primary surface and near-surface carbon was CO2. Finally, the delay in oxidation of Earth’s surface following oxygenic photosynthesis is problematical if early photosynthesizers had a vast CO2 source from early degassing. Given an abundant food supply, what prevented early cyanobacteria from rapidly oxidizing the surface? Although discovery of CO2-rich atmospheres on Venus and Mars seem to support CO2 as the primary surface carbon reservoir, these atmospheres are the result of atmospheric evolution, particularly loss of H to space. ALL of these problems disappear with early degassing of reduced gases such as CH4 and NH3. Considerations of meteoritic compositions, accretionary processes, and early atmosphere/hydrosphere chemical processing all support reduced gases as dominant in the early atmospheres of the terrestrial planets. The time has come to revert to any earlier idea of strongly reducing conditions on early terrestrial planet surfaces, followed by long-term evolutionary trends toward oxidation.

  2. On the origin and early evolution of terrestrial planet atmospheres and meteoritic volatiles

    Microsoft Academic Search

    R. O. Pepin

    1991-01-01

    A model is presented which attempts to synthesize previous efforts to place the origin of planetary atmosphere and meteorite volatiles in a context more fully integrated with concepts concerning the early (and evolving) astrophysical environment of the solar system. While the model combines familiar primordial components and theories, it differs from earlier approaches in that (1) the full ranges of

  3. The Atmospheres of the Terrestrial Planets:Clues to the Origins and Early Evolution of Venus, Earth, and Mars

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; Atreya, Sushil K.; Bullock, Mark A.; Grinspoon, David H,; Mahaffy, Paul; Russell, Christopher T.; Schubert, Gerald; Zahnle, Kevin

    2015-01-01

    We review the current state of knowledge of the origin and early evolution of the three largest terrestrial planets - Venus, Earth, and Mars - setting the stage for the chapters on comparative climatological processes to follow. We summarize current models of planetary formation, as revealed by studies of solid materials from Earth and meteorites from Mars. For Venus, we emphasize the known differences and similarities in planetary bulk properties and composition with Earth and Mars, focusing on key properties indicative of planetary formation and early evolution, particularly of the atmospheres of all three planets. We review the need for future in situ measurements for improving our understanding of the origin and evolution of the atmospheres of our planetary neighbors and Earth, and suggest the accuracies required of such new in situ data. Finally, we discuss the role new measurements of Mars and Venus have in understanding the state and evolution of planets found in the habitable zones of other stars.

  4. Terrestrial atmosphere, water and astrobiology

    Microsoft Academic Search

    A. Brack; M. Coradini

    2010-01-01

    Primitive life, defined as a chemical system capable to transfer its molecular information via self-replication and also capable to evolve, originated about 4 billion years ago from the processing of organic molecules by liquid water. Terrestrial atmosphere played a key role in the process by allowing the permanent presence of liquid water and by participating in the production of carbon-based

  5. Terrestrial atmosphere, water and astrobiology

    NASA Astrophysics Data System (ADS)

    Brack, A.; Coradini, M.

    2010-12-01

    Primitive life, defined as a chemical system capable to transfer its molecular information via self-replication and also capable to evolve, originated about 4 billion years ago from the processing of organic molecules by liquid water. Terrestrial atmosphere played a key role in the process by allowing the permanent presence of liquid water and by participating in the production of carbon-based molecules. Water molecules exhibit specific properties mainly due to a dense network of hydrogen bonds. The carbon-based molecules were either home made in the atmosphere and/or in submarine hydrothermal systems or delivered by meteorites and micrometeorites. The search for possible places beyond the earth where the trilogy atmosphere/water/life could exist is the main objective of astrobiology. Within the Solar System, exploration missions are dedicated to Mars, Europa, Titan and the icy bodies. The discovery of several hundreds of extrasolar planets opens the quest to the whole Milky Way.

  6. Synthetic spectra of simulated terrestrial atmospheres containing possible biomarker gases.

    PubMed

    Schindler, T L; Kasting, J F

    2000-05-01

    NASA's proposed Terrestrial Planet Finder, a space-based interferometer, will eventually allow spectroscopic analyses of the atmospheres of extrasolar planets. Such analyses would provide information about the existence of life on these planets. One strategy in the search for life is to look for evidence of O3 (and hence O2) in a planet's atmosphere; another is to look for gases that might be present in an atmosphere analogous to that of the inhabited early Earth. In order to investigate these possibilities, we have calculated synthetic spectra for several hypothetical terrestrial-type atmospheres. The model atmospheres represent four different scenarios. The first two, representing inhabited terrestrial planets, are an Earth-like atmosphere containing variable amounts of oxygen and an early Earth-type atmosphere containing methane. In addition, two cases representing Mars-like and early Venus-like atmospheres were evaluated, to provide possible "false positive" spectra. The calculated spectra suggest that ozone could be detected by an instrument like Terrestrial Planet Finder if the O2 concentration in the planet's atmosphere is > or = 200 ppm, or 10(-3) times the present atmospheric level. Methane should be observable on an early-Earth type planet if it is present in concentrations of 100 ppm or more. Methane has both biogenic and abiogenic sources, but concentrations exceeding 1000 ppm, or 0.1% by volume, would be difficult to produce from abiogenic sources alone. High methane concentrations in a planet's atmosphere are therefore another potential indicator for extraterrestrial life. PMID:11543302

  7. Terrestrial proxy records of subtropical atmospheric dynamics during the early to mid-Holocene from the interior southeastern United States

    NASA Astrophysics Data System (ADS)

    Kocis, J. J.

    2009-12-01

    The interior southeastern United States presents an opportune location for examining linkages among the timing, movement and influence of subtropical air masses upon terrestrial ecosystems. However, proxy based reconstructions, which may record the interplay of such circulation patterns, are lacking for northern subtropical latitudes of this region. Presented here are analyses of well-dated sediment cores collected from multiple floodplains of the Tennessee River in northern Alabama and southeastern Tennessee. Centennial-scale variability in alluvial sequence stratigraphy, stable carbon isotope values of soil organic matter (?13CSOM) and C3-C4 vegetation mixing models are used to interpret the changes in riparian paleohydrological balances from 9000-4000 cal yr BP. Age-depth models of clay/sand weight percentage ratios are used to determine secular trends in the increase or decrease of overbank sedimentation. Results of paleoflood modeling indicate periods of increased flooding from 7400-7200 and from 6800-6200 cal yr BP, which are followed by rapid decrease in overbank sedimentation after 5000 cal yr BP. Results of isotopic analyses indicate that during the early Holocene, ?13CSOM values average -25‰ VPDB (71-76% C3) and vary by 1-2‰ from 6200-5000 cal yr BP. After 5000 cal yr BP, abrupt excursions to -28‰ (89-93% C3) occur until values return to the average -25‰ VPDB by 4000 cal yr BP. Secular trends in these riparian ecosystem proxies are interpreted to reflect the northeastern movement of the Bermuda High, wetter than modern conditions and an increase in El Niño activity during the early Holocene. The transition out of the mid-Holocene is characterized by a decrease in flood events and a return to average ?13CSOM of -25‰ VPDB. By 4000 cal yr BP, these riparian proxies are reflect the southwestern migration of the Bermuda High, decreased El Niño activity and a return to average modern climatic conditions over the interior southeastern United States.

  8. Terrestrial proxy records of subtropical atmospheric dynamics during the early to mid-Holocene from the interior southeastern United States

    Microsoft Academic Search

    J. J. Kocis

    2009-01-01

    The interior southeastern United States presents an opportune location for examining linkages among the timing, movement and influence of subtropical air masses upon terrestrial ecosystems. However, proxy based reconstructions, which may record the interplay of such circulation patterns, are lacking for northern subtropical latitudes of this region. Presented here are analyses of well-dated sediment cores collected from multiple floodplains of

  9. Terrestrial Planet Atmospheres and Biosignatures

    Microsoft Academic Search

    V. Meadows; S. Seager

    2010-01-01

    The search for terrestrial exoplanets - rocky worlds in orbit around stars other than the Sun - is one of humanity's most exciting science goals. The discovery of super Earths, terrestrial planets more massive than Earth, has opened a new era in exoplanet science, confirming the basic idea that our solar system is not the only planetary system to harbor

  10. Impact erosion of terrestrial planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.

    1992-01-01

    I review current ideas about the nature of the planetesimals - composition, size distribution, and the planetary encounter velocity. Previous papers on accretion and erosion of planetary atmospheres as a result of multiple impacts are reviewed. Finally, the effects of blowing off a substantial fraction of the atmosphere from a terrestrial planet due to a single giant body impact are discussed.

  11. The development of early terrestrial ecosystems

    E-print Network

    Selden, Paul A.; Edwards, Dianne

    1993-01-01

    In this review of terrestrialization by plants and animals in the early Phanerozoic, the classical idea of a major mid-Palaeozoic event is discarded in favour of gradual colonization over a long time period. Four phases ...

  12. Linkages between terrestrial ecosystems and the atmosphere

    NASA Technical Reports Server (NTRS)

    Bretherton, Francis; Dickinson, Robert E.; Fung, Inez; Moore, Berrien, III; Prather, Michael; Running, Steven W.; Tiessen, Holm

    1992-01-01

    The primary research issue in understanding the role of terrestrial ecosystems in global change is analyzing the coupling between processes with vastly differing rates of change, from photosynthesis to community change. Representing this coupling in models is the central challenge to modeling the terrestrial biosphere as part of the earth system. Terrestrial ecosystems participate in climate and in the biogeochemical cycles on several temporal scales. Some of the carbon fixed by photosynthesis is incorporated into plant tissue and is delayed from returning to the atmosphere until it is oxidized by decomposition or fire. This slower (i.e., days to months) carbon loop through the terrestrial component of the carbon cycle, which is matched by cycles of nutrients required by plants and decomposers, affects the increasing trend in atmospheric CO2 concentration and imposes a seasonal cycle on that trend. Moreover, this cycle includes key controls over biogenic trace gas production. The structure of terrestrial ecosystems, which responds on even longer time scales (annual to century), is the integrated response to the biogeochemical and environmental constraints that develop over the intermediate time scale. The loop is closed back to the climate system since it is the structure of ecosystems, including species composition, that sets the terrestrial boundary condition in the climate system through modification of surface roughness, albedo, and, to a great extent, latent heat exchange. These separate temporal scales contain explicit feedback loops which may modify ecosystem dynamics and linkages between ecosystems and the atmosphere. The long-term change in climate, resulting from increased atmospheric concentrations of greenhouse gases (e.g., CO2, CH4, and nitrous oxide (N2O)) will further modify the global environment and potentially induce further ecosystem change. Modeling these interactions requires coupling successional models to biogeochemical models to physiological models that describe the exchange of water, energy, and biogenic trace gases between the vegetation and the atmosphere at fine time scales. There does not appear to be any obvious way to allow direct reciprocal coupling of atmospheric general circulation models (GCM's), which inherently run with fine time steps, to ecosystem or successional models, which have coarse temporal resolution, without the interposition of physiological canopy models. This is equally true for biogeochemical models of the exchange of carbon dioxide and trace gases. This coupling across time scales is nontrivial and sets the focus for the modeling strategy.

  13. Solar-terrestrial coupling through atmospheric electricity

    NASA Technical Reports Server (NTRS)

    Roble, R. G.; Hays, P. B.

    1979-01-01

    There are a number of measurements of electrical variations that suggest a solar-terrestrial influence on the global atmospheric electrical circuit. The measurements show variations associated with solar flares, solar magnetic sector boundary crossings, geomagnetic activity, aurorae, differences between ground current and potential gradients at high and low latitudes, and solar cycle variations. The evidence for each variation is examined. Both the experimental evidence and the calculations made with a global model of atmospheric electricity indicate that there is solar-terrestrial coupling through atmospheric electricity which operates by altering the global electric current and field distribution. A global redistribution of currents and fields can be caused by large-scale changes in electrical conductivity, by alteration of the columnar resistance between thunderstorm cloud tops and the ionosphere, or by both. If the columnar resistance is altered above thunderstorms, more current will flow in the global circuit, changing the ionospheric potential and basic circuit variables such as current density and electric fields. The observed variations of currents and fields during solar-induced disturbances are generally less than 50% of mean values near the earth's surface.

  14. Atmospheric Circulation of Terrestrial Exoplanets Adam P. Showman

    E-print Network

    extending to the discovery and characterization of super-Earths and terrestrial planets. Motivated the fundamental dynamical principles governing the atmospheric circulation on terrestrial planets--broadly defined). Despite a major emphasis to date on extrasolar giant planets (EGPs), super Earths and terrestrial planets

  15. Sulfuric acid aerosols in the atmospheres of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    McGouldrick, Kevin; Toon, Owen B.; Grinspoon, David H.

    2011-08-01

    Clouds and hazes composed of sulfuric acid are observed to exist or postulated to have once existed on each of the terrestrial planets with atmospheres in our solar system. Venus today maintains a global cover of clouds composed of a sulfuric acid/water solution that extends in altitude from roughly 50 km to roughly 80 km. Terrestrial polar stratospheric clouds (PSCs) form on stratospheric sulfuric acid aerosols, and both PSCs and stratospheric aerosols play a critical role in the formation of the ozone hole. Stratospheric aerosols can modify the climate when they are enhanced following volcanic eruptions, and are a current focus for geoengineering studies. Rain is made more acidic by sulfuric acid originating from sulfur dioxide generated by industry on Earth. Analysis of the sulfur content of Martian rocks has led to the hypothesis that an early Martian atmosphere, rich in SO 2 and H 2O, could support a sulfur-infused hydrological cycle. Here we consider the plausibility of frozen sulfuric acid in the upper clouds of Venus, which could lead to lightning generation, with implications for observations by the European Space Agency's Venus Express and the Japan Aerospace Exploration Agency's Venus Climate Orbiter (also known as Akatsuki). We also present simulations of a sulfur-rich early Martian atmosphere. We find that about 40 cm/yr of precipitation having a pH of about 2.0 could fall in an early Martian atmosphere, assuming a surface temperature of 273 K, and SO 2 generation rates consistent with the formation of Tharsis. This modeled acid rain is a powerful sink for SO 2, quickly removing it and preventing it from having a significant greenhouse effect.

  16. Terrestrial sources and distribution of atmospheric sulphur

    PubMed Central

    Lelieveld, J.; Roelofs, G.-J.; Ganzeveld, L.; Feichter, J.; Rodhe, H.

    1997-01-01

    The general circulation model ECHAM has been coupled to a chemistry and sulphur cycle model to study the impact of terrestrial, i.e. mostly anthropogenic sulphur dioxide (SO2), sources on global distributions of sulphur species in the atmosphere. We briefly address currently available source inventories. It appears that global estimates of natural emissions are associated with uncertainties up to a factor of 2, while anthropogenic emissions have uncertainty ranges of about +/- 30 per cent. Further, some recent improvements in the model descriptions of multiphase chemistry and deposition processes are presented. Dry deposition is modelled consistently with meteorological processes and surface properties. The results indicate that surface removal of SO2 is less efficient than previously assumed, and that the SO2 lifetime is thus longer. Coupling of the photochemistry and sulphur chemistry schemes in the model improves the treatment of multiphase processes such as oxidant (hydrogen peroxide) supply in aqueous phase SO2 oxidation. The results suggest that SO2 oxidation by ozone (O3) in the aqueous phase is more important than indicated in earlier work. However, it appears that we still overestimate atmospheric SO2 concentrations near the surface in the relatively polluted Northern Hemisphere. On the other hand, we somewhat underestimate sulphate levels in these regions, which suggests that additional heterogeneous reaction mechanisms, e.g. on aerosols, enhance SO2 oxidation.

  17. Transient simulations of Holocene atmospheric carbon dioxide and terrestrial carbon since the Last

    E-print Network

    Fortunat, Joos

    , terrestrial carbon uptake and release, SST changes, and coral reef buildup, contributed to the 20 ppm rise buildup, and land use have probably influenced atmospheric CO2 by a few ppm only. The early Holocene CO2 revision of land use emission estimates by a factor of 3 to 4. INDEX TERMS: 0322 Atmospheric Composition

  18. Sulfuric acid aerosols in the atmospheres of the terrestrial planets

    Microsoft Academic Search

    Kevin McGouldrick; Owen B. Toon; David H. Grinspoon

    2011-01-01

    Clouds and hazes composed of sulfuric acid are observed to exist or postulated to have once existed on each of the terrestrial planets with atmospheres in our solar system. Venus today maintains a global cover of clouds composed of a sulfuric acid\\/water solution that extends in altitude from roughly 50 km to roughly 80 km. Terrestrial polar stratospheric clouds (PSCs)

  19. Sulfuric acid aerosols in the atmospheres of the terrestrial planets

    Microsoft Academic Search

    Kevin McGouldrick; Owen B. Toon; David H. Grinspoon

    2011-01-01

    Clouds and hazes composed of sulfuric acid are observed to exist or postulated to have once existed on each of the terrestrial planets with atmospheres in our solar system. Venus today maintains a global cover of clouds composed of a sulfuric acid\\/water solution that extends in altitude from roughly 50km to roughly 80km. Terrestrial polar stratospheric clouds (PSCs) form on

  20. Impact of terrestrial weather on the upper atmosphere

    Microsoft Academic Search

    T. J. Fuller-Rowell; R. A. Akmaev; F. Wu; A. Anghel; N. Maruyama; D. N. Anderson; M. V. Codrescu; M. Iredell; S. Moorthi; H.-M. Juang; Y.-T. Hou; G. Millward

    2008-01-01

    A whole atmosphere model has been developed to demonstrate the impact of terrestrial weather on the upper atmosphere. The dynamical core is based on the NWS Global Forecast System model, which has been extended to cover altitudes from the ground to 600 km. The model includes the physical processes responsible for the stochastic nature of the lower atmosphere, which is

  1. Trophic network models explain instability of Early Triassic terrestrial communities

    E-print Network

    Roopnarine, Peter D.

    Trophic network models explain instability of Early Triassic terrestrial communities Peter D al. 2005), and the post-extinction Early Triassic world was characterized by degraded terrestrial and the effect of community structure on such extinctions. Here we use a trophic network model that combines

  2. PHOTOCHEMISTRY IN TERRESTRIAL EXOPLANET ATMOSPHERES. II. H?S AND SO? PHOTOCHEMISTRY IN ANOXIC ATMOSPHERES

    E-print Network

    Hu, Renyu

    Sulfur gases are common components in the volcanic and biological emission on Earth, and are expected to be important input gases for atmospheres on terrestrial exoplanets. We study the atmospheric composition and the ...

  3. Terrestrial nitrous oxide cycles and atmospheric effects

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Lawless, J. G.; Banin, A.

    1984-01-01

    The basic processes that cause N2O emission from soils are briefly discussed, and the rate of the processes is shown to vary widely in space and time, depending on soil, climate, and agrotechnical conditions. Although significant amounts of N2O are indeed emitted from the land, the complexity of the soil processes involved and the wide variation of measured rates still prevents the quantitative evaluation, global budgeting, and reliable prediction of atmospheric N2O. Increased atmospheric N2O abundance increases the levels of odd-nitrogen in the stratosphere, which, in turn, decreases the stratospheric ozone density via a catalytic cycle. Using appropriate atmospheric models and current chemical kinetic data, it has been found that the dependence of ozone reduction on N2O increase is nearly linear; a simulated doubling of N2O leads to a predicted decrease of about 14 percent in total ozone column density. A 10 percent increase in N2O yields a predicted increase in nonmelanoma skin cancer of several percent, and a possible raising of surface temperature of 0.03 K.

  4. Space, Atmospheric, and Terrestrial Radiation Environments

    NASA Technical Reports Server (NTRS)

    Barth, Janet L.; Dyer, C. S.; Stassinopoulos, E. G.

    2003-01-01

    The progress on developing models of the radiation environment since the 1960s is reviewed with emphasis on models that can be applied to predicting the performance of microelectronics used in spacecraft and instruments. Space, atmospheric, and ground environments are included. It is shown that models must be adapted continually to account for increased understanding of the dynamics of the radiation environment and the changes in microelectronics technology. The IEEE Nuclear and Space Radiation Effects Conference is a vital forum to report model progress to the radiation effects research community.

  5. Aerial bursts in the terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Shuvalov, V. V.; Trubetskaya, I. A.

    2007-06-01

    Impacts of cosmic bodies (stony and comet-like) are considered that “burn out” (or, more strictly, totally evaporate) in the atmosphere, which do not form craters but cause fires and destruction on the Earth’s surface. The heights of fragmentation, total evaporation, and deceleration of stony and comet-like meteoroids of different sizes, initial velocities, and impact angles are found from numerical simulations. The possible consequences of such falls are considered. The possible parameters of the Tunguska cosmic body are estimated.

  6. The Atmospheric and Terrestrial Mobile Laboratory (ATML).

    SciTech Connect

    Zak, Bernard Daniel; Rahn, Thom (Los Alamos National Laboratory); Nitschke, Kim (Los Alamos National Laboratory); Ivey, Mark D.; Mora, Claudia (Los Alamos National Laboratory); McDowell, Nate (Los Alamos National Laboratory); Love, Steve (Los Alamos National Laboratory); Dubey, M. (Los Alamos National Laboratory); Michelsen, Hope A.; Guilderson, Tom (Lawrence Livermore National Laboratory); Schubert, William Kent; Costigan, Keeley (Los Alamos National Laboratory); Chylek, Petr (Los Alamos National Laboratory); Bambha, Ray P.; Roskovensky, John K.

    2010-04-01

    The ionospheric disturbance dynamo signature in geomagnetic variations is investigated using the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model. The model results are tested against reference magnetically quiet time observations on 21 June 1993, and disturbance effects were observed on 11 June 1993. The model qualitatively reproduces the observed diurnal and latitude variations of the geomagnetic horizontal intensity and declination for the reference quiet day in midlatitude and low-latitude regions but underestimates their amplitudes. The patterns of the disturbance dynamo signature and its source 'anti-Sq' current system are well reproduced in the Northern Hemisphere. However, the model significantly underestimates the amplitude of disturbance dynamo effects when compared with observations. Furthermore, the largest simulated disturbances occur at different local times than the observations. The discrepancies suggest that the assumed high-latitude storm time energy inputs in the model were not quantitatively accurate for this storm.

  7. Hydrogen and climate in primitive terrestrial and super-Earth atmospheres (Invited)

    NASA Astrophysics Data System (ADS)

    Wordsworth, R.

    2013-12-01

    For the three terrestrial planets with significant atmospheres in the Solar System (Earth, Venus and Mars), present-day conditions are oxidizing, with combinations of CO2, N2, O2 and H2O dominating by mass and in terms of the greenhouse effect. However, primitive terrestrial or ';super-Earth' exoplanet atmospheres may be much more reducing (i.e., hydrogen-rich), with major implications for climate, composition, and pre-biotic chemistry. Here I discuss recent work on the role of hydrogen in terrestrial planetary atmospheres, with a particular focus on the early Earth. I describe how collision-induced absorption (CIA) by hydrogen may have significantly warmed Earth's surface in the Archean and Hadean by blocking the critical water vapour absorption window at 800-1200 cm-1. This warming may have helped mitigate the faint young Sun effect early on. After the emergence of widespread methanogenesis, the consumption of H2 and CO2 should have led to a global shift in climate, with potentially observable consequences in the geological record. Because of variations in planetary mass, stellar XUV input and outgassing rates, hydrogen is also likely to be an important component of many super-Earth atmospheres. As I will discuss, this should have a significant effect on climate evolution and the carbon cycle on such planets, which should be considered in future predictions of atmospheric spectra and biosignatures.

  8. Sulphur cycling between terrestrial agroecosystem and atmosphere.

    PubMed

    Zgorelec, Zeljka; Pehnec, Gordana; Baši?, Ferdo; Kisi?, Ivica; Mesi?, Milan; Zužul, Silva; Juriši?, Aleksandra; Sestak, Ivana; Va?i?, Vladimira; Ca?kovi?, Mirjana

    2012-09-01

    Central gas station of the natural gas borehole system Podravina is located near the village Molve. It delivers more than a quarter of total energy used in Croatia to its consumers. Over the years, adapting technology to increasingly demanding and rigorous standards in environmental protection has become paramount. Yet, despite all the industry has undertaken to address the risk of harmful substances entering the food chain, a multidisciplinary research team of independent scientists monitors the content of specific substances in all components of the ecosystem. This paper presents measurements of total sulphur contents in soil surface [(0 to 3) cm] and subsurface [(3 to 8) cm] layers (study period: autumn 2006 - spring 2010) and in plants (study period: spring 2000 - spring 2010), and the concentration of gaseous sulphur compounds in the air. Concentrations of hydrogen sulphide (H2S) and mercaptans (RSH) were measured from the summer of 2002 until the autumn of 2010, while concentrations of sulphur dioxide (SO2) were measured from the spring of 2008 until the autumn of 2010. The paper also shows total annual atmospheric sulphur (S-SO4) deposition at Bilogora measuring station (study period: 2001 - 2010). Average monthly concentrations of H2S in air varied between 0.2 ?g m-3 and 2.0 ?g m-3, RSH between 0.1 ?g m-3 and 24.5 ?g m-3, and SO2 between 0.4 ?g m-3 and 2.8 ?g m-3 depending on the location and the season of sampling. Mean values of total sulphur in soil and in Plantago lanceolata plant ranged between 610 mg kg-1 and 1,599 mg kg-1 and between 3,614 mg kg-1 and 4,342 mg kg-1, respectively, depending on the soil type, location, and sampling depth. Average values of total sulphur mass ratio for all examined single soil samples (n=80) were 1,080 mg kg-1 for both studied layers, and 4,108 mg kg-1 for all analysed plant samples (n=85). Average total annual atmospheric sulphur deposition at Bilogora measuring station was 6.3 kg of S-SO4 per hectare. PMID:23152380

  9. Solar Wind Ablation of Terrestrial Planet Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas Earle; Fok, Mei-Ching H.; Delcourt, Dominique C.

    2009-01-01

    Internal plasma sources usually arise in planetary magnetospheres as a product of stellar ablation processes. With the ignition of a new star and the onset of its ultraviolet and stellar wind emissions, much of the volatiles in the stellar system undergo a phase transition from gas to plasma. Condensation and accretion into a disk is replaced by radiation and stellar wind ablation of volatile materials from the system- Planets or smaller bodies that harbor intrinsic magnetic fields develop an apparent shield against direct stellar wind impact, but UV radiation still ionizes their gas phases, and the resulting internal plasmas serve to conduct currents to and from the central body along reconnected magnetic field linkages. Photoionization and thermalization of electrons warms the ionospheric topside, enhancing Jeans' escape of super-thermal particles, with ambipolar diffusion and acceleration. Moreover, observations and simulations of auroral processes at Earth indicate that solar wind energy dissipation is concentrated by the geomagnetic field by a factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Thus internal plasmas enable coupling with the plasma, neutral gas and by extension, the entire body. The stellar wind is locally loaded and slowed to develop the required power. The internal source plasma is accelerated and heated, inflating the magnetosphere as it seeks escape, and is ultimately blown away in the stellar wind. Bodies with little sensible atmosphere may still produce an exosphere of sputtered matter when exposed to direct solar wind impact. Bodies with a magnetosphere and internal sources of plasma interact more strongly with the stellar wind owing to the magnetic linkage between the two created by reconnection.

  10. On the condensating species in terrestrial extrasolar planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Patzer, A. B. C.; von Paris, P.; Kitzmann, D.; Rauer, H.; Grenfell, J. L.

    2008-09-01

    ABSTRACT The formation of liquid droplets and/or solid particles has a significant impact on the thermal, dynamic, and chemical structure of the planetary environments, in which they are formed. For example, the character and distribution of the atmospheric condensates determine the appearance of such objects. It is therefore important to know, which chemical species might condense under the atmospheric conditions of extrasolar planets and how the condensate, solid or maybe liquid, nucleate in detail to finally form cloudy structures in such planetary atmospheres. In this contribution the presence of particles of likely condensates under atmospheric conditions of extrasolar terrestrial planets is discussed. Consequences regarding the condensation of major gaseous constituents of the planetary atmospheres are considered in particular. Selected applications, especially in view of the recently discovered low mass planets - so called Super-Earths -, are presented and compared. Acknowledgement: This work has been partly supported by the Forschungsallianz Planetary Evolution and Life of the Helmholtz Gemeinschaft (HGF).

  11. New constraints on terrestrial and oceanic sources of atmospheric methanol

    NASA Astrophysics Data System (ADS)

    Millet, D. B.; Jacob, D. J.; Custer, T. G.; de Gouw, J. A.; Goldstein, A. H.; Karl, T.; Singh, H. B.; Sive, B. C.; Talbot, R. W.; Warneke, C.; Williams, J.

    2008-04-01

    We use a global 3-D chemical transport model (GEOS-Chem) to interpret new aircraft, surface, and oceanic observations of methanol in terms of the constraints that they place on the atmospheric methanol budget. Recent measurements of methanol concentrations in the ocean mixed layer (OML) imply that in situ biological production must be the main methanol source in the OML, dominating over uptake from the atmosphere. It follows that oceanic emission and uptake must be viewed as independent terms in the atmospheric methanol budget. We deduce that the marine biosphere is a large primary source (85 Tg y-1) of methanol to the atmosphere and is also a large sink (101 Tg y-1), comparable in magnitude to atmospheric oxidation by OH (88 Tg y-1). The resulting atmospheric lifetime of methanol in the model is 4.7 days. Aircraft measurements in the North American boundary layer imply that terrestrial plants are a much weaker source than presently thought, likely reflecting an overestimate of broadleaf tree emissions, and this is also generally consistent with surface measurements. We deduce a terrestrial plant source of 80 Tg y-1, comparable in magnitude to the ocean source. The aircraft measurements show a strong correlation with CO (R2=0.51-0.61). We reproduce this correlation in the model with the reduced plant source, which also confirms that the anthropogenic source of methanol must be small. Our reduced plant source also provides a better simulation of methanol observations over tropical South America.

  12. Atmospheric circulation and climate of terrestrial exoplanets and super Earths

    NASA Astrophysics Data System (ADS)

    Showman, A. P.; Kaspi, Y.

    2014-03-01

    The recent discovery of super Earths and terrestrial exoplanets extending over a broad region of orbital and physical parameter space suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone--including transitions to Snowball-like states and runaway-greenhouse feedbacks--depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. In this presentation we will review how the planetary rotation rate, planetary mass, heat flux from a parent star and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. We will elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we will discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.

  13. Constraints on Early Mars atmospheric pressure

    E-print Network

    Kite, Edwin

    Constraints on Early Mars atmospheric pressure from small ancient craters impactors, so impact crater size is a probe of atmospheric pressure. ebar4bar Diameter (m) Fractionofcraterssmallerthan ! Atmospheric pressure upper limit

  14. Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere

    NASA Technical Reports Server (NTRS)

    Kharchenko, Vasili

    2004-01-01

    We have investigated the impact of hot metastable oxygen atoms on the product yields and rate coefficients of atmospheric reactions involving O( (sup 1)D). The contribution of the metastable oxygen atoms to the thermal balance of the terrestrial atmosphere between 50 and 200 km has been determined. We found that the presence of hot O((sup l)D) atoms in the mesosphere and lower thermosphere significantly increases the production rate of the rotationally-vibrationally excited NO molecules. The computed yield of the NO molecules in N2O+ O((sup 1)D) atmospheric collisions, involving non-Maxwellian distributions of the metastable oxygen atoms, is more than two times larger than the NO-yield at a thermal equilibrium. The calculated non-equilibrium rate and yield functions are important for ozone and nitrous oxide modeling in the stratosphere, mesosphere and lower thermosphere.

  15. Abiotic Oxygen-dominated Atmospheres on Terrestrial Habitable Zone Planets

    NASA Astrophysics Data System (ADS)

    Wordsworth, Robin; Pierrehumbert, Raymond

    2014-04-01

    Detection of life on other planets requires identification of biosignatures, i.e., observable planetary properties that robustly indicate the presence of a biosphere. One of the most widely accepted biosignatures for an Earth-like planet is an atmosphere where oxygen is a major constituent. Here we show that lifeless habitable zone terrestrial planets around any star type may develop oxygen-dominated atmospheres as a result of water photolysis, because the cold trap mechanism that protects H2O on Earth is ineffective when the atmospheric inventory of non-condensing gases (e.g., N2, Ar) is low. Hence the spectral features of O2 and O3 alone cannot be regarded as robust signs of extraterrestrial life.

  16. New constraints on terrestrial and oceanic sources of atmospheric methanol

    NASA Astrophysics Data System (ADS)

    Millet, D. B.; Jacob, D. J.; Custer, T. G.; de Gouw, J. A.; Goldstein, A. H.; Karl, T.; Singh, H. B.; Sive, B. C.; Talbot, R. W.; Warneke, C.; Williams, J.

    2008-12-01

    We use a global 3-D chemical transport model (GEOS-Chem) to interpret new aircraft, surface, and oceanic observations of methanol in terms of the constraints that they place on the atmospheric methanol budget. Recent measurements of methanol concentrations in the ocean mixed layer (OML) imply that in situ biological production must be the main methanol source in the OML, dominating over uptake from the atmosphere. It follows that oceanic emission and uptake must be viewed as independent terms in the atmospheric methanol budget. We deduce that the marine biosphere is a large primary source (85 Tg a-1) of methanol to the atmosphere and is also a large sink (101 Tg a-1), comparable in magnitude to atmospheric oxidation by OH (88 Tg a-1). The resulting atmospheric lifetime of methanol in the model is 4.7 days. Aircraft measurements in the North American boundary layer imply that terrestrial plants are a much weaker source than presently thought, likely reflecting an overestimate of broadleaf tree emissions, and this is also generally consistent with surface measurements. We deduce a terrestrial plant source of 80 Tg a-1, comparable in magnitude to the ocean source. The aircraft measurements show a strong correlation with CO (R2=0.51-0.61) over North America during summer. We reproduce this correlation and slope in the model with the reduced plant source, which also confirms that the anthropogenic source of methanol must be small. Our reduced plant source also provides a better simulation of methanol observations over tropical South America.

  17. Atmospheric and water loss from early Venus

    NASA Astrophysics Data System (ADS)

    Kulikov, Yu. N.; Lammer, H.; Lichtenegger, H. I. M.; Terada, N.; Ribas, I.; Kolb, C.; Langmayr, D.; Lundin, R.; Guinan, E. F.; Barabash, S.; Biernat, H. K.

    2006-11-01

    Previous interpretations of the Pioneer Venus mass spectrometer data of the deuterium to hydrogen (D/H) ratio of 1.9×10-2 or 120±40 times the terrestrial value indicate that Venus may have had at least an H2O content of the order of about 0.3% of a terrestrial ocean (TO), and even much more during and shortly after the accretion period of ?300Myr, depending on the unknown ratio of a continuous supply of H2O by comets to a hydrogen blow-off loss and impact erosion of the early atmosphere. In view of the low H2O abundance in the present atmosphere, several studies suggest that the planet should have lost most of its H2O during the early high X-ray, EUV and solar wind period of the active young Sun. Because oxygen did not accumulate in Venus' atmosphere it is commonly believed that a part of the oxygen from dissociated H2O vapor was dragged off to space along with the escaping hydrogen during a blow-off period, or could have oxidized the surface minerals to produce FeO and Fe2O3 to the depths of a few kilometers to tens of kilometers depending on the initial amount of H2O. We use in the present study, for the first time, multi-wavelength X-ray and EUV (XUV) observations by the ASCA, ROSAT, EUVE, FUSE and IUE satellites and stellar winds inferred from mass loss observations by the Hubble Space Telescope of solar proxies with ages <4.6Gyr for the investigation of how efficiently the radiation and particle environment of the young Sun could have influenced the evolution of the early Venusian atmosphere and its H2O inventory due to the removal of oxygen picked up by the solar wind. For modelling the Venusian thermosphere over the planetary history we apply a diffusive-gravitational equilibrium and thermal balance model and investigate the heating of the early thermosphere by photodissociation and ionization processes, due to exothermic chemical reactions and cooling by CO2 IR emission in the 15?m band. Our model simulations result in expanded thermospheres with exobase levels between about 200 km at present and about 2200 km 4.5 Gyr ago. Moreover, our results yield high exospheric temperatures during the active phase of the young Sun even if we assume a "dry" CO2 atmosphere with similar composition that is observed on present Venus of more than 8000 K after the Sun arrived at the zero-age-main-sequence (ZAMS). Exospheric temperatures above about 4000 K lead to diffusion-limited escape and high loss rates for atomic hydrogen. The duration of this blow-off phase for atomic hydrogen essentially depends on the mixing ratios of CO2, N2 and H2O in the early Venusian atmosphere and could last between about 150 to several hundred Myr, which could result in a large thermal loss of hydrogen from Venus. For studying how much of the H2O-related oxygen could have been lost to space by the ion pick up process due to the stronger solar wind and higher XUV fluxes of the young Sun we used our modelled atmospheric density profiles and studied the loss of O+ ion pick up from the upper atmosphere of Venus over the planet's history by applying a numerical test particle model. Depending on the used solar wind parameters, our model simulations show that ion pick up by a strong early solar wind on a non-magnetized Venus could erode during 4.6 Gyr more than about 250 bar of O+ ions, that corresponds to an equivalent amount of one terrestrial ocean. Finally, we discuss the implications of our findings for the formation of the Venusian atmosphere and discuss our results in the frame of previous studies.

  18. Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere

    NASA Technical Reports Server (NTRS)

    Kharchenko, Vasili; Dalgarno, A.

    2005-01-01

    This report summarizes our research performed under NASA Grant NAG5-11857. The three-year grant have been supported by the Geospace Sciences SR&T program. We have investigated the energetic metastable oxygen and nitrogen atoms in the terrestrial stratosphere, mesosphere and thermosphere. Hot atoms in the atmosphere are produced by solar radiation, the solar wind and various ionic reactions. Nascent hot atoms arise in ground and excited electronic states, and their translational energies are larger by two - three orders of magnitude than the thermal energies of the ambient gas. The relaxation kinetics of hot atoms determines the rate of atmospheric heating, the intensities of aeronomic reactions, and the rate of atom escape from the planet. Modeling of the non-Maxwellian energy distributions of metastable oxygen and nitrogen atoms have been focused on the determination of their impact on the energetics and chemistry of the terrestrial atmosphere between 25 and 250 km . At this altitudes, we have calculated the energy distribution functions of metastable O and N atoms and computed non-equilibrium rates of important aeronomic reactions, such as destruction of the water molecules by O(1D) atoms and production of highly excited nitric oxide molecules. In the upper atmosphere, the metastable O(lD) and N(2D) play important role in formation of the upward atomic fluxes. We have computed the upward fluxes of the metastable and ground state oxygen atoms in the upper atmosphere above 250 km. The accurate distributions of the metastable atoms have been evaluated for the day and night-time conditions.

  19. Early Martian environments - The antarctic and other terrestrial analogs

    NASA Technical Reports Server (NTRS)

    Wharton, R. A., Jr.; Mckay, C. P.; Mancinelli, R. L.; Simmons, G. M., Jr.

    1989-01-01

    The comparability of the early environments of Mars and earth, and the biological evolution which occurred on early earth, motivates serious consideration of the possibility of an early Martian biota. Environments which could have contained this early Martian life and which may presently contain evidence of this former life include aquatic, ice, soil, and rock habitats. Several analogs of these potential early Martian environments, which can provide useful information in searching for extinct life on Mars, are currently available for study on earth. These terrestrial analogs include the perennially ice-covered lakes and sandstone rocks in the polar deserts of Antarctica, surface of snowfields and glaciers, desert soils, geothermal springs, and deep subsurface environments.

  20. Morphological Biosignatures in Early Terrestrial and Extraterrestrial Materials

    NASA Astrophysics Data System (ADS)

    Westall, Frances

    2008-03-01

    Biosignatures in early terrestrial rocks are highly relevant in the search for traces of life on Mars because the early geological environments of the two planets were, in many respects, similar and, thus, the potential habitats for early life forms were similar. However, the identification and interpretation of biosignatures in ancient terrestrial rocks has proven contentious over the last few years. Recently, new investigations using very detailed field studies combined with highly sophisticated analytical techniques have begun to document a large range of biosignatures in Early Archaean rocks. Early life on Earth was diversified, widespread and relatively evolved, but its traces are generally, but not always, small and subtle. In this contribution I use a few examples of morphological biosignatures from the Early-Mid Archaean to demonstrate their variety in terms of size and type: macroscopic stromatolites from the 3.443 Ga Strelley Pool Chert, Pilbara; a meso-microscopic microbial mat from the 3.333 Ga Josefsdal Chert, Barberton; microscopic microbial colonies and a biofilm from the 3.446 Ga Kitty’s Gap Chert, Pilbara; and microscopic microbial corrosion pits in the glassy rinds of 3.22-3.48 Ga pillow lavas from Barberton. Some macroscopic and microscopic structures may be identifiable in an in situ robotic mission to Mars and in situ methods of organic molecule detection may be able to reveal organic traces of life. However, it is concluded that it will probably be necessary to return suitably chosen Martian rocks to Earth for the reliable identification of signs of life, since multiple observational and analytical methods will be necessary, especially if Martian life is significantly different from terrestrial life.

  1. Morphological Biosignatures in Early Terrestrial and Extraterrestrial Materials

    NASA Astrophysics Data System (ADS)

    Westall, Frances

    Biosignatures in early terrestrial rocks are highly relevant in the search for traces of life on Mars because the early geological environments of the two planets were, in many respects, similar and, thus, the potential habitats for early life forms were similar. However, the identification and interpretation of biosignatures in ancient terrestrial rocks has proven contentious over the last few years. Recently, new investigations using very detailed field studies combined with highly sophisticated analytical techniques have begun to document a large range of biosignatures in Early Archaean rocks. Early life on Earth was diversified, widespread and relatively evolved, but its traces are generally, but not always, small and subtle. In this contribution I use a few examples of morphological biosignatures from the Early-Mid Archaean to demonstrate their variety in terms of size and type: macroscopic stromatolites from the 3.443 Ga Strelley Pool Chert, Pilbara; a meso-microscopic microbial mat from the 3.333 Ga Josefsdal Chert, Barberton; microscopic microbial colonies and a biofilm from the 3.446 Ga Kitty's Gap Chert, Pilbara; and microscopic microbial corrosion pits in the glassy rinds of 3.22-3.48 Ga pillow lavas from Barberton. Some macroscopic and microscopic structures may be identifiable in an in situ robotic mission to Mars and in situ methods of organic molecule detection may be able to reveal organic traces of life. However, it is concluded that it will probably be necessary to return suitably chosen Martian rocks to Earth for the reliable identification of signs of life, since multiple observational and analytical methods will be necessary, especially if Martian life is significantly different from terrestrial life.

  2. Coupling Terrestrial and Atmospheric Water Dynamics to Improve Prediction in a Changing Environment

    E-print Network

    Lyon, Steve W.; Dominguez, Francina; Gochis, David J.; Brunsell, Nathaniel A.; Castro, Christopher; Chow, Fotini K.; Fan, Ying; Fuka, Daniel; Hong, Yang; Kucera, Paul A.; Nesbitt, Stephen W.; Salzmann, Nadine; Schmidli, Juerg; Snyder, Peter K.; Teuling, Adriaam J.; Twine, Tracy E.; Levis, Samuel; Lundquist, Jessica D.; Salvucci, Guido D.; Sealy, Andrea M.; Walter, M. Todd

    2008-09-01

    Fluxes across the land surface directly influence predictions of ecological processes, atmospheric dynamics, and terrestrial hydrology. However, many simplifications are made in numerical models when considering ...

  3. Early oxygenation of the terrestrial environment during the Mesoproterozoic.

    PubMed

    Parnell, John; Boyce, Adrian J; Mark, Darren; Bowden, Stephen; Spinks, Sam

    2010-11-11

    Geochemical data from ancient sedimentary successions provide evidence for the progressive evolution of Earth's atmosphere and oceans. Key stages in increasing oxygenation are postulated for the Palaeoproterozoic era (?2.3?billion years ago, Gyr ago) and the late Proterozoic eon (about 0.8?Gyr ago), with the latter implicated in the subsequent metazoan evolutionary expansion. In support of this rise in oxygen concentrations, a large database shows a marked change in the bacterially mediated fractionation of seawater sulphate to sulphide of ?(34)S?atmospheric oxygen concentrations and the evolution of non-photosynthetic sulphide-oxidizing bacteria. Here we report ?(34)S values exceeding 50‰ from a terrestrial Mesoproterozoic (1.18?Gyr old) succession in Scotland, a time period that is at present poorly characterized. This level of fractionation implies disproportionation in the sulphur cycle, probably involving sulphide-oxidizing bacteria, that is not evident from ?(34)S data in the marine record. Disproportionation in both red beds and lacustrine black shales at our study site suggests that the Mesoproterozoic terrestrial environment was sufficiently oxygenated to support a biota that was adapted to an oxygen-rich atmosphere, but had also penetrated into subsurface sediment. PMID:21068840

  4. Terrestrial ecosystem regulation of interannual variability in atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Keppel-Aleks, G.; Randerson, J. T.; Mu, M.; Doney, S. C.; van der Werf, G.; Collatz, G. J.; Morton, D. C.

    2013-12-01

    Linking interannual variability in the global carbon dioxide, CO2, growth rate to its ecological and physical drivers may provide a means to improve predictions of long-term carbon-climate feedbacks. Many studies have attributed variability in the global CO2 record to a single factor, such as temperature, drought, or fire, or have asserted a combination of controls using complex ecosystem models. The evolving temporal and spatial structure of atmospheric CO2 may enable a more effective attribution of these processes, but has not been used systematically for this purpose. Here we simulated the fingerprints that terrestrial fluxes of carbon originating from temperature and drought stress and biomass burning imprint on the latitudinal and temporal distribution atmospheric CO2 for the 1997-2009 period using the GEOS-Chem atmospheric model. In general, temperature, precipitation, and drought signatures were highly correlated across different latitude bands, indicating that no single factor was the dominant mechanism explaining most of the CO2 variability. Fires had a unique signature, particularly in the northern hemisphere as a consequence of large events in the boreal forest during 1998, 2004, and 2008. Statistical models that combined these factors were able to explain between 20% and 40% of the CO2 variability in the northern hemisphere and 40-50% in the southern hemisphere. Net ecosystem exchange fluxes from the tropics, temperature, precipitation, and drought time series explained a considerable amount of flux variability in the NH and SH extra-tropics. Fires accounted for 25% to 30% of the total modeled variability in the NH (north of 23N) with this amount decreasing to about 20% in the SH (south of 23S). We also examined results from CMIP5 coupled Earth System Models to quantify patterns of variability in atmospheric CO2 originating from terrestrial ecosystems. We compared the variations correlated with temperature and precipitation variability to estimate the apparent climate sensitivity over the historical period, and examined the implications for long term carbon storage as climate changes. The results from these generalized simulations show that accounting for the latitudinal variability in atmospheric CO2 as well as the time-lag from transport facilitates a better relationship between fluxes and observed variations.

  5. Atmospheric Escape and Climate Evolution of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Tian, F.; Chassefière, E.; Leblanc, F.; Brain, D.

    The climate of a planet is primarily determined by its orbital distance from its star, the luminosity of the star, the existence of oceans, the pressure of its atmosphere, and the composition of its atmosphere. The last two components are what could be impacted by atmosphere escape. The Sun, as the dominant energy source driving the climate of terrestrial planets, was not always as bright as it is today. Stellar evolution theory predicts that the luminosity of the young Sun was 75% of its present luminosity, at approximately 4 b.y. ago (4 Ga) (Gough, 1981). Although the Sun could have lost some of its mass, thus making the very young Sun somewhat more massive than it is now and therefore could have emitted more energy, most of this mass loss was completed prior to 4 Ga (Wood et al., 2005). Thus the Sun has provided increasingly more energy to solar system planets during the past 4 b.y. Contrary to the evolutionary trend of the total luminosity increasing with time, the young Sun should have emitted much stronger EUV, soft X-ray, and far-UV photons than at present. These photons are from the upper atmosphere of the Sun and are linked to solar magnetic activity. Generally speaking, a young star rotates much faster and thus has stronger magnetic activity. Observations of solar-type stars with different ages show that the EUV energy flux from a 0.5-b.y.-old solar-type star could be as much as 20 times that of the present Sun (Ribas et al., 2005). Accompanying this much-enhanced solar extreme ultraviolet (XUV) radiation is a much stronger solar wind, with mass flux up to 1000 times more intense than the present solar wind flux (Wood et al., 2005). It can be expected that many more energetic-particle events were caused by the young Sun. The fate of the atmospheres of terrestrial planets in such an environment and the consequences for their climates are the focus of this chapter.

  6. Contribution of natural terrestrial sources to the atmospheric chloroform budget

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Abel, T.; Pan, D.; Whelan, M.

    2008-12-01

    Chloroform (trichloromethane, CHCl3) is the second largest carrier of natural chlorine in the troposphere after methyl chloride, contributing to the reactive chlorine burden in the troposphere and to ozone destruction in the stratosphere. Our understanding of the biogeochemical cycling of atmospheric CHCl3 has undergone major adjustments recently, including the quantification of the total atmospheric burden of this compound, the estimated global source and sink strengths, and the relative contributions of anthropogenic versus natural contributions. Numerous natural terrestrial sources have been identified, including temperate peatlands, Arctic tundra, termite mounds, salt marshes, grasslands, forests and woodlands. However, the wide variability of fluxes within each ecosystem has complicated efforts to quantify the overall terrestrial source. In addition, the environmental and biogeochemical controls remain largely unknown. We shall present a comparison of recent CHCl3 flux measurements that cover a range of biome types and climatic conditions. To address within-biome variability, flux measurements from the Arctic tundra and temperate grasslands will be compared to common environmental parameters (e.g., temperature, soil moisture, solar insolation) and other trace gas fluxes (CH3Cl, CH4, CCl4). The generally poor correlations demonstrate that the variability of CHCl3 emissions may be affected by site-specific parameters that are not currently measured or by drastic changes in hydrologic conditions. Similar patterns are observed in laboratory incubations of tundra peat and grassland soils. We explore the possibility that the humification of plant material, which has been shown to produce organochlorine compounds through the chlorination of organic matter, may contribute to CHCl3 emissions. If this link exists, then CHCl3 production could potentially act as a proxy for organic matter degradation and carbon sequestration, essential biogeochemical and ecosystem processes.

  7. Three dimensional atmospheric dynamics of terrestrial exoplanets over a wide range of orbital and atmospheric parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Y.; Showman, A. P.

    2014-04-01

    The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters, suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone-including transitions to Snowballlike states and runaway-greenhouse feedbacks-depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.

  8. Atmospheric dynamics of terrestrial exoplanets over a wide range of orbital and atmospheric parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Showman, Adam

    2014-05-01

    The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters, suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone--including transitions to Snowball-like states and runaway-greenhouse feedbacks--depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star, atmospheric mass and optical thickness affect the atmospheric circulation and temperature distribution on such planets. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.

  9. HfW chronology of the accretion and early evolution of asteroids and terrestrial planets

    E-print Network

    Nimmo, Francis

    Hf­W chronology of the accretion and early evolution of asteroids and terrestrial planets Thorsten and earliest evolution of asteroids and terrestrial planets and lead to the following succession and duration- nometer for this major differentiation event. However, for larger planets such as the terrestrial planets

  10. A massive early atmosphere on Triton

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.; Nolan, Michael C.

    1992-01-01

    The idea of an early greenhouse atmosphere for Triton is presented and the conditions under which it may have been sustained are quantified. The volatile content of primordial Triton is modeled, and tidal heating rates are assessed to set bounds on the available energy. The atmospheric model formalism is presented, and it is shown how a massive atmosphere could have been raised by modest tidal heating fluxes. The implications of the model atmospheres for the atmospheric escape rates, the chemical evolution, and the cratering record are addressed.

  11. North America's net terrestrial CO2 exchange with the atmosphere 1990-2009

    NASA Astrophysics Data System (ADS)

    King, A. W.; Andres, R. J.; Davis, K. J.; Hafer, M.; Hayes, D. J.; Huntzinger, D. N.; de Jong, B.; Kurz, W. A.; McGuire, A. D.; Vargas, R.; Wei, Y.; West, T. O.; Woodall, C. W.

    2015-01-01

    Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) project, this paper provides a synthesis of net land-atmosphere CO2 exchange for North America (Canada, United States, and Mexico) over the period 1990-2009. Only CO2 is considered, not methane or other greenhouse gases. This synthesis is based on results from three different methods: atmospheric inversion, inventory-based methods and terrestrial biosphere modeling. All methods indicate that the North American land surface was a sink for atmospheric CO2, with a net transfer from atmosphere to land. Estimates ranged from -890 to -280 Tg C yr-1, where the mean of atmospheric inversion estimates forms the lower bound of that range (a larger land sink) and the inventory-based estimate using the production approach the upper (a smaller land sink). This relatively large range is due in part to differences in how the approaches represent trade, fire and other disturbances and which ecosystems they include. Integrating across estimates, "best" estimates (i.e., measures of central tendency) are -472 ± 281 Tg C yr-1 based on the mean and standard deviation of the distribution and -360 Tg C yr-1 (with an interquartile range of -496 to -337) based on the median. Considering both the fossil fuel emissions source and the land sink, our analysis shows that North America was, however, a net contributor to the growth of CO2 in the atmosphere in the late 20th and early 21st century. With North America's mean annual fossil fuel CO2 emissions for the period 1990-2009 equal to 1720 Tg C yr-1 and assuming the estimate of -472 Tg C yr-1 as an approximation of the true terrestrial CO2 sink, the continent's source : sink ratio for this time period was 1720:472, or nearly 4:1.

  12. Atmospheric Dynamics of Terrestrial Exoplanets Over a Wide Range of Orbital and Atmospheric Parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Showman, Adam P.

    2014-11-01

    Since the mid-1990s, nearly 1800 exoplanets have been discovered around other stars. Exoplanet discovery and characterization began with giant planets, but as the observational techniques are advancing the emphasis is gradually shifting to smaller worlds. The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone---including transitions to Snowball-like states and runaway-greenhouse feedbacks---depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we discuss the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star, optical thickness and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet stream, Hadley and Ferrel cells and latitudinal temperature differences. Finally, we will discuss how the atmospheric dynamics influence the global-scale climate feedbacks that control the width of the habitable zone, and their effects on the global climate.

  13. Terrestrial Sources and Sinks of Atmospheric Methyl Bromide: Three-Dimensional Modeling of

    E-print Network

    Terrestrial Sources and Sinks of Atmospheric Methyl Bromide: Three-Dimensional Modeling biomass burning fluxes and other known terrestrial sources and sinks. Modeled sensitivities to biomass-4307 USA ACCESS: Tel: (617) 253-4902 Fax: (617) 253-0354 E-mail: globalchange@mit.edu World Wide Web: http

  14. Atmospheric photochemistry, surface features, and potential biosignature gases of terrestrial exoplanets

    E-print Network

    Hu, Renyu, Ph. D. Massachusetts Institute of Technology

    2013-01-01

    The endeavor to characterize terrestrial exoplanets warrants the study of chemistry in their atmospheres. Here I present a comprehensive one-dimensional photochemistry-thermochemistry model developed from the ground up for ...

  15. Large impact events and atmospheric evolution on the terrestrial planets

    SciTech Connect

    Grinspoon, D.H.

    1989-01-01

    The first task undertaken is the characterization of the impact rates in the inner solar system during the present time, and during the first billion years of Solar System history when the flux was changing rapidly. Once defined, these fluxes are used to model the long term cumulative effect of multiple impacts on planetary atmospheres. The implications of cometary impacts on evolution of the water and deuterium abundances on Venus are examined. The short lifetime of water on Venus suggests that the water abundance is in quasi-steady-state balance between loss by escape and replenishment by infall. In addition, the observed deuterium-to-hydrogen ratio on Venus is consistent with a steady state and does not necessarily imply a past water excess. Results are presented of a model incorporating a stochastic cometary source and nonthermal escape of hydrogen that produces the observed water abundance and D/H ratio. The stochastic variability of each of these quantities is shown to be large. Water on Venus is likely to be in a near steady state mediated by large comet impacts. The early history of water on the planet has been obscured by a history of random impacts. A study of the effects of impact-generated dust clouds on the primitive Earth leads to the conclusion that such clouds were significant perturbers of the early climate. The Earth was shrouded by an optically-thick dust cloud for {approx}150-250 m.y.. During this time the surface temperature was equal to the planetary equilibrium temperature unless significant heating by impacts or surface heat flow existed beneath the dust cloud. The epoch of continuous dust shrouding was followed by a period of stochastically intermittent dust clouds occurring at greater intervals as the early intense bombardment subsided towards the present day flux.

  16. The Early Origins of Terrestrial C4 Photosynthesis

    NASA Astrophysics Data System (ADS)

    Tipple, Brett J.; Pagani, Mark

    2007-05-01

    The C4 photosynthetic pathway is a series of structural and biochemical modifications around the more primitive C3 pathway that improve the photosynthetic efficiency under specific climatic conditions. Hence, the origin and subsequent geographical expansion of the C4 plants likely reflects a record of climate change. Multiple paleoatmospheric pCO2 proxies indicate a critical CO2 threshold was breached 30 Ma, that potentially selected for CO2-concentrating mechanisms to overcome photorespiratory stresses imposed on the basic C3 pathway. Details of the C4 pathway's earliest origins remain enigmatic given the paucity of the geologic record. Nonetheless, ?13C proxy records from paleosol carbonates, ungulate teeth, and plant-derived compounds indicate C4 plants likely represented an important component of plant biomass by the Early Miocene. Low CO2 levels appear to be a precondition for the development of the C4 photosynthetic pathway; however, comparisons of ?13C proxy records indicate that the timing of C4 geographical expansion was not globally synchronous, and thus point toward more regional controls on the development of C4-dominated ecosystems. Terrestrial and marine records indicate that continental aridity and wind strength increased during the Late Miocene. These conditions would have likely increased fire occurrence and fire intensity leading to the clearing of large tree stands and the expansion of C4 grasses in warm-season precipitation regimes.

  17. Photochemistry of methane in the earth's early atmosphere

    NASA Astrophysics Data System (ADS)

    Kasting, J. F.; Zahnle, K. J.; Walker, J. C. G.

    The photochemical behavior of methane in the early terrestrial atmosphere is investigated with a detailed model in order to determine how much CH4 might have been present and what types of higher hydroocarbons could have been formed. It is found that any primordial methane accumulated during the course of earth accretion would have been dissipated by photochemical reactions in the atmosphere in a geologically short period of time after the segregation of the core. Abiotic sources of methane are not likely to have been large enough to sustain CH4 mixing ratios as high as 10 to the -6th, the threshold for a possible methane greenhouse, with a CO-rich atmosphere being a possible exception. After the origin of life an increasing biogenic source of methane may have driven CH4 mixing ratios well above 10 to the 6th. The rise of atmospheric oxygen in the early Proterozoic may have led to a more rapid photochemical destruction of methane, lowering the mixing ratio to its present value.

  18. The Center for the Study of Terrestrial and Extraterrestrial Atmospheres (CSTEA)

    NASA Technical Reports Server (NTRS)

    Thorpe, Arthur N.; Morris, Vernon R.

    1997-01-01

    The Center for the Study of Terrestrial and Extraterrestrial Atmospheres (CSTEA) was established in 1992. The center began with 14 active Principal Investigators (PI's). The research of the Center's PIs has, for the most part, continued in the same four areas as presented in the original proposal: Remote Sensing, Atmospheric Chemistry, Sensors and Detectors, and Spacecraft Dynamics.

  19. Effects of atmospheric ammonia (NH 3) on terrestrial vegetation: a review

    Microsoft Academic Search

    S. V Krupa

    2003-01-01

    At the global scale, among all N (nitrogen) species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH3 (ammonia) is considered to be the foremost. The major sources for atmospheric NH3 are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to

  20. Atmospheric transport of persistent pollutants governs uptake by holarctic terrestrial biota

    SciTech Connect

    Larsson, P.; Okla, L.; Woin, Per (Limnology, Lund (Sweden))

    1990-10-01

    The atmospheric deposition of PCBs, DDT, and lindane, governed uptake in terrestrial biota in the Scandinavian peninsula. Mammalian herbivores and predators as well as predatory insects contained higher levels of pollutants at locations where the fallout load was high than at stations where atmospheric deposition was lower, and the two variables were significantly correlated.

  1. Evaluation of terrestrial carbon cycle models with atmospheric CO2 measurements: Results from transient simulations considering increasing CO2, climate, and land-use effects

    USGS Publications Warehouse

    Dargaville, R.J.; Heimann, M.; McGuire, A.D.; Prentice, I.C.; Kicklighter, D.W.; Joos, F.; Clein, J.S.; Esser, G.; Foley, J.; Kaplan, J.; Meier, R.A.; Melillo, J.M.; Moore, B., III; Ramankutty, N.; Reichenau, T.; Schloss, A.; Sitch, S.; Tian, H.; Williams, L.J.; Wittenberg, U.

    2002-01-01

    An atmospheric transport model and observations of atmospheric CO2 are used to evaluate the performance of four Terrestrial Carbon Models (TCMs) in simulating the seasonal dynamics and interannual variability of atmospheric CO2 between 1980 and 1991. The TCMs were forced with time varying atmospheric CO2 concentrations, climate, and land use to simulate the net exchange of carbon between the terrestrial biosphere and the atmosphere. The monthly surface CO2 fluxes from the TCMs were used to drive the Model of Atmospheric Transport and Chemistry and the simulated seasonal cycles and concentration anomalies are compared with observations from several stations in the CMDL network. The TCMs underestimate the amplitude of the seasonal cycle and tend to simulate too early an uptake of CO2 during the spring by approximately one to two months. The model fluxes show an increase in amplitude as a result of land-use change, but that pattern is not so evident in the simulated atmospheric amplitudes, and the different models suggest different causes for the amplitude increase (i.e., CO2 fertilization, climate variability or land use change). The comparison of the modeled concentration anomalies with the observed anomalies indicates that either the TCMs underestimate interannual variability in the exchange of CO2 between the terrestrial biosphere and the atmosphere, or that either the variability in the ocean fluxes or the atmospheric transport may be key factors in the atmospheric interannual variability.

  2. Origin of the atmospheres of the terrestrial planets

    Microsoft Academic Search

    A Cameron

    1983-01-01

    The monotonic decrease in the atmospheric abundance of per gram of planet in the sequence, Venus, earth, and Mars has been assumed to reflect some conditions in the primitive solar nebula at the time of formation of the planetary atmospheres, having to do either with the composition of the nebula itself or the composition of the trapped gases in small

  3. Journal of Atmospheric and Solar-Terrestrial Physics 66 (2004) 17791790 The possible connection between ionization in the atmosphere

    E-print Network

    Journal of Atmospheric and Solar-Terrestrial Physics 66 (2004) 1779­1790 The possible connection. O'Brienc a Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane Department of Physics and Astronomy, Northern Arizona University PMB 1019, 2675 W. Hwy. 89A, Sedona, AZ 86336

  4. Detectability of biosignature gases in the atmospheres of terrestrial exoplanets

    E-print Network

    Messenger, Stephen Joseph

    2013-01-01

    Biosignature gases in the atmosphere of an exoplanet provide a means by which we can deduce the possible existence of life on that planet. As the list of possible biosignature gases is ever growing, the need to determine ...

  5. The early atmosphere: a new picture.

    PubMed

    Levine, J S

    1986-01-01

    Over the last several years, many of the fundamental ideas concerning the composition and chemical evolution of the Earth's early atmosphere have changed. While many aspects of this subject are clouded--either uncertain or unknown, a new picture is emerging. We are just beginning to understand how astronomical, geochemical, and atmospheric processes each contributed to the development of the gaseous envelope around the third planet from the sun some 4.6 billion years ago and how that envelope chemically evolved over the history of our planet. Simple compounds in that gaseous envelope, energized by atmospheric lightning and/or solar ultraviolet radiation, formed molecules of increasing complexity that eventually evolved into the first living systems on our planet. This process is called "chemical evolution" and immediately preceded biological evolution; once life developed and evolved, it began to alter the chemical composition of the atmosphere that provided the very essence of its creation. Photosynthetic organisms which have the ability to biochemically transform carbon dioxide and water to carbohydrates, which they use for food, produce large amounts of molecular oxygen (O2) as a by-product of the reaction. Atmospheric oxygen photochemically formed ozone, which absorbs ultraviolet radiation from the sun and shields the Earth's surface from this biologically lethal radiation. Once atmospheric ozone levels increased sufficiently, life could leave the safety of the oceans and go ashore for the first time. Throughout the history of our planet, there has been strong interaction between life and the atmosphere. Understanding our cosmic roots is particularly relevant as we embark on a search for life outside the Earth. At this very moment, several radio telescopes around the world are searching for extraterrestrial intelligence (SETI). PMID:11542093

  6. PHOTOCHEMISTRY IN TERRESTRIAL EXOPLANET ATMOSPHERES. I. PHOTOCHEMISTRY MODEL AND BENCHMARK CASES

    SciTech Connect

    Hu Renyu; Seager, Sara; Bains, William, E-mail: hury@mit.edu [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)] [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2012-12-20

    We present a comprehensive photochemistry model for exploration of the chemical composition of terrestrial exoplanet atmospheres. The photochemistry model is designed from the ground up to have the capacity to treat all types of terrestrial planet atmospheres, ranging from oxidizing through reducing, which makes the code suitable for applications for the wide range of anticipated terrestrial exoplanet compositions. The one-dimensional chemical transport model treats up to 800 chemical reactions, photochemical processes, dry and wet deposition, surface emission, and thermal escape of O, H, C, N, and S bearing species, as well as formation and deposition of elemental sulfur and sulfuric acid aerosols. We validate the model by computing the atmospheric composition of current Earth and Mars and find agreement with observations of major trace gases in Earth's and Mars' atmospheres. We simulate several plausible atmospheric scenarios of terrestrial exoplanets and choose three benchmark cases for atmospheres from reducing to oxidizing. The most interesting finding is that atomic hydrogen is always a more abundant reactive radical than the hydroxyl radical in anoxic atmospheres. Whether atomic hydrogen is the most important removal path for a molecule of interest also depends on the relevant reaction rates. We also find that volcanic carbon compounds (i.e., CH{sub 4} and CO{sub 2}) are chemically long-lived and tend to be well mixed in both reducing and oxidizing atmospheres, and their dry deposition velocities to the surface control the atmospheric oxidation states. Furthermore, we revisit whether photochemically produced oxygen can cause false positives for detecting oxygenic photosynthesis, and find that in 1 bar CO{sub 2}-rich atmospheres oxygen and ozone may build up to levels that have conventionally been accepted as signatures of life, if there is no surface emission of reducing gases. The atmospheric scenarios presented in this paper can serve as the benchmark atmospheres for quickly assessing the lifetime of trace gases in reducing, weakly oxidizing, and highly oxidizing atmospheres on terrestrial exoplanets for the exploration of possible biosignature gases.

  7. The Upper Valanginian (Early Cretaceous) positive carbon–isotope event recorded in terrestrial plants

    Microsoft Academic Search

    Darren R. Gröcke; Gregory D. Price; Stuart A. Robinson; Evgenij Y. Baraboshkin; Jörg Mutterlose; Alastair H. Ruffell

    2005-01-01

    Our understanding of the ancient ocean-atmosphere system has focused on oceanic proxies. However, the study of terrestrial proxies is equally necessary to constrain our understanding of ancient climates and linkages between the terrestrial and oceanic carbon reservoirs. We have analyzed carbon–isotope ratios from fossil plant material through the Valanginian and Lower Hauterivian from a shallow-marine, ammonite-constrained succession in the Crimean

  8. The Upper Valanginian (Early Cretaceous) positive carbon-isotope event recorded in terrestrial plants [rapid communication

    Microsoft Academic Search

    Darren R. Gröcke; Gregory D. Price; Stuart A. Robinson; Evgenij Y. Baraboshkin; Jörg Mutterlose; Alastair H. Ruffell

    2005-01-01

    Our understanding of the ancient ocean-atmosphere system has focused on oceanic proxies. However, the study of terrestrial proxies is equally necessary to constrain our understanding of ancient climates and linkages between the terrestrial and oceanic carbon reservoirs. We have analyzed carbon isotope ratios from fossil plant material through the Valanginian and Lower Hauterivian from a shallow-marine, ammonite-constrained succession in the

  9. Planetary Atmospheres Earth and the Other Terrestrial Worlds

    E-print Network

    Crenshaw, Michael

    make planetary surfaces warmer through greenhouse effect #12;3 Greenhouse Effect · Visible light passes without greenhouse effect · Earth would be 31°C colder (below freezing on average) Thought Question What space Where does an atmosphere end? · Small amounts of gas are present even at > 300 km Effects

  10. Relocation of Southwestern US Terrestrial Moisture through Atmospheric Pathways

    NASA Astrophysics Data System (ADS)

    Dominguez, F.; Villegas, J. C.; Breshears, D.

    2007-12-01

    Evapotranspiration accounts for the majority of the water budget in arid and semiarid regions such as the Southwestern U.S. Using a Lagrangian analytical model forced with North American Regional Reanalysis (NARR) data, we are able to identify the regions where this evapotranspired moisture is advected and eventually falls as precipitation. Our work shows that moisture originating from evapotranspiration in the Southwestern US contributes to precipitation throughout North America, particularly the Central Plains and the Midwestern US. Evapotranspiration and the subsequent export of moisture are particularly important during the North American monsoon season, when the combination of increased soil moisture, energy availability and atmospheric demand promotes the transference of water to the atmosphere via direct evaporation from the soil or transpiration by vegetation. Moisture evapotranspired in the four corners region of the Southwest contributes to an average 15% of the total summer precipitation in regions of Wyoming, Nebraska and Kansas. We find that during the 2000- 2003 drought period, the decrease in precipitation and evapotranspiration within the four corners region significantly decreased the amount of recycled precipitation of downwind regions. Due to the uncertainty in NARR evapotranspiration, observations and independent model outputs are used as validation. Our study illustrates the importance of moisture transport through atmospheric pathways, a process that links the surface hydrologic stores and atmospheric moisture fluxes.

  11. The Martian atmospheric water cycle as viewed from a terrestrial perspective

    NASA Technical Reports Server (NTRS)

    Zurek, Richard W.

    1988-01-01

    It is noted that the conditions of temperature and pressure that characterize the atmosphere of Mars are similar to those found in the Earth's stratosphere. Of particular significance is the fact that liquid water is unstable in both environments. Thus, it is expected that terrestrial studies of the dynamical behavior of stratospheric water should benefit the understanding of water transport on Mars as well.

  12. A Large Northern Hemisphere Terrestrial CO_2 Sink Indicated by the 13C\\/12C Ratio of Atmospheric CO_2

    Microsoft Academic Search

    P. Ciais; P. P. Tans; M. Trolier; J. W. C. White; R. J. Francey

    1995-01-01

    Measurements of the concentrations and carbon-13\\/carbon-12 isotope ratios of atmospheric carbon dioxide can be used to quantify the net removal of carbon dioxide from the atmosphere by the oceans and terrestrial plants. A study of weekly samples from a global network of 43 sites defined the latitudinal and temporal patterns of the two carbon sinks. A strong terrestrial biospheric sink

  13. Photonuclear production of cosmogenic beryllium-7 in the terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Bezuglov, M. V.; Malyshevsky, V. S.; Fomin, G. V.; Torgovkin, A. V.; Shramenko, B. I.; Malykhina, T. V.

    2012-08-01

    Average N(?,X)7Be, O(?,X)7Be, and C(?,X)7Be cross sections of the natural composition of target isotopes in an energy range from threshold to 90 MeV are measured. By using cross sections of the photoproduction of 7Be and a simulation of the nuclear-electromagnetic cascade in the atmosphere, the contribution from the photonuclear mechanism into the production of a cosmogenic 7Be radionuclide in the Earth's atmosphere is investigated. It is shown that the contribution from the photonuclear channel into the production of cosmogenic 7Be is to be taken into account in processes of the accumulation and transfer of 7Be in the ground layer.

  14. Stability of ammonia in the primitive terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Kasting, J. F.

    1982-04-01

    The rate at which ammonia would have been destroyed in the earth's atmosphere under assumed NH3 mixing ratio conditions of 10 to the -8th to 0.0001 is calculated by a one-dimensional photochemical model, and the destruction rates are compared with possible biotic and abiotic ammonia sources. It is found that, while the mixing ratio of 10 to the -8th needed for the evolution of life could have been maintained by abiotic sources, the value of 0.00001 needed for the production of significant greenhouse warming could not have been sustained abiotically. The increase of atmospheric ammonia due to biological activities during the Archean is also considered lower than the level required for the generation of measurable thermal effects.

  15. Synchronized Terrestrial-Atmospheric Deglacial Records Around the North Atlantic

    Microsoft Academic Search

    Svante Bjorck; Bernd Kromer; Sigfus Johnsen; Ole Bennike; Dan Hammarlund; Geoffrey Lemdahl; Goran Possnert; Tine Lander Rasmussen; Barbara Wohlfarth; Claus Uffe Hammer; Marco Spurk

    1996-01-01

    On the basis of synchronization of three carbon-14 (14C)-dated lacustrine sequences from Sweden with tree ring and ice core records, the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450 to 11,390 ± 80 years before the present. A 150-year-long cooling in the early Preboreal, associated with rising delta14C values, is evident in all records and

  16. An impact-induced terrestrial atmosphere and iron-water reactions during accretion of the Earth

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1985-01-01

    Shock wave data and theoretical calculations were used to derive models of an impact-generated terrestrial atmosphere during accretion of the Earth. The models showed that impacts of infalling planetesimals not only provided the entire budget of terrestrial water but also led to a continuous depletion of near-surface layers of water-bearing minerals of their structural water. This resulted in a final atmospheric water reservoir comparable to the present day total water budget of the Earth. The interaction of metallic iron with free water at the surface of the accreting Earth is considered. We carried out model calcualtions simulating these processes during accretion. It is assumed that these processes are the prime source of the terrestrial FeO component of silicates and oxides. It is demonstrated that the iron-water reaction would result in the absence of atmospheric/hydrospheric water, if homogeneous accretion is assumed. In order to obtain the necessary amount of terrestrial water, slightly heterogeneous accretion with initially 36 wt% iron planetesimals, as compared with a homogeneous value of 34 wt% is required.

  17. PHOTOCHEMISTRY IN TERRESTRIAL EXOPLANET ATMOSPHERES. II. H{sub 2}S AND SO{sub 2} PHOTOCHEMISTRY IN ANOXIC ATMOSPHERES

    SciTech Connect

    Hu Renyu; Seager, Sara; Bains, William, E-mail: hury@mit.edu [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-05-20

    Sulfur gases are common components in the volcanic and biological emission on Earth, and are expected to be important input gases for atmospheres on terrestrial exoplanets. We study the atmospheric composition and the spectra of terrestrial exoplanets with sulfur compounds (i.e., H{sub 2}S and SO{sub 2}) emitted from their surfaces. We use a comprehensive one-dimensional photochemistry model and radiative transfer model to investigate the sulfur chemistry in atmospheres ranging from reducing to oxidizing. The most important finding is that both H{sub 2}S and SO{sub 2} are chemically short-lived in virtually all types of atmospheres on terrestrial exoplanets, based on models of H{sub 2}, N{sub 2}, and CO{sub 2} atmospheres. This implies that direct detection of surface sulfur emission is unlikely, as their surface emission rates need to be extremely high (>1000 times Earth's volcanic sulfur emission) for these gases to build up to a detectable level. We also find that sulfur compounds emitted from the surface lead to photochemical formation of elemental sulfur and sulfuric acid in the atmosphere, which would condense to form aerosols if saturated. For terrestrial exoplanets in the habitable zone of Sun-like stars or M stars, Earth-like sulfur emission rates result in optically thick haze composed of elemental sulfur in reducing H{sub 2}-dominated atmospheres for a wide range of particle diameters (0.1-1 {mu}m), which is assumed as a free parameter in our simulations. In oxidized atmospheres composed of N{sub 2} and CO{sub 2}, optically thick haze, composed of elemental sulfur aerosols (S{sub 8}) or sulfuric acid aerosols (H{sub 2}SO{sub 4}), will form if the surface sulfur emission is two orders of magnitude more than the volcanic sulfur emission of Earth. Although direct detection of H{sub 2}S and SO{sub 2} by their spectral features is unlikely, their emission might be inferred by observing aerosol-related features in reflected light with future generation space telescopes.

  18. Time-Dependent Simulations of the Formation and Evolution of Disk-Accreted Atmospheres Around Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Stoekl, Alexander; Dorfi, Ernst

    2014-05-01

    In the early, embedded phase of evolution of terrestrial planets, the planetary core accumulates gas from the circumstellar disk into a planetary envelope. This atmosphere is very significant for the further thermal evolution of the planet by forming an insulation around the rocky core. The disk-captured envelope is also the staring point for the atmospheric evolution where the atmosphere is modified by outgassing from the planetary core and atmospheric mass loss once the planet is exposed to the radiation field of the host star. The final amount of persistent atmosphere around the evolved planet very much characterizes the planet and is a key criterion for habitability. The established way to study disk accumulated atmospheres are hydrostatic models, even though in many cases the assumption of stationarity is unlikely to be fulfilled. We present, for the first time, time-dependent radiation hydrodynamics simulations of the accumulation process and the interaction between the disk-nebula gas and the planetary core. The calculations were performed with the TAPIR-Code (short for The adaptive, implicit RHD-Code) in spherical symmetry solving the equations of hydrodynamics, gray radiative transport, and convective energy transport. The models range from the surface of the solid core up to the Hill radius where the planetary envelope merges into the surrounding protoplanetary disk. Our results show that the time-scale of gas capturing and atmospheric growth strongly depends on the mass of the solid core. The amount of atmosphere accumulated during the lifetime of the protoplanetary disk (typically a few Myr) varies accordingly with the mass of the planet. Thus, a core with Mars-mass will end up with about 10 bar of atmosphere while for an Earth-mass core, the surface pressure reaches several 1000 bar. Even larger planets with several Earth masses quickly capture massive envelopes which in turn become gravitationally unstable leading to runaway accretion and the eventual formation of a gas planet.

  19. Mercury in terrestrial biomass and soils and factors determining atmospheric mercury sequestration

    NASA Astrophysics Data System (ADS)

    Obrist, D.; Johnson, D. W.; Lindberg, S.; Luo, Y.

    2008-12-01

    Terrestrial carbon (C) pools play an important role in uptake, deposition, sequestration, and emission of atmospheric mercury (Hg). The objective of this study is to assess atmospheric Hg sequestration associated with vegetation and soil C pools in forest ecosystems. As part of an ongoing EPA STAR project, we are systematically evaluating Hg pools and fluxes associated with terrestrial C pools in all major ecosystem compartments (i.e., leaves, branches, bole, litter, soils) across selected US forest ecosystems. Results from the first five sites located in the remote western United States show that the dominant above-ground pool of mercury is associated with surface litter with smaller pools associated with leaves and branches. Mass concentrations greatly increase in the following order: green leaves, dry leaves, initial litter, partially decomposed litter, humus. Based on detailed comparison of stochiometric relationships (e.g., Hg/C and Hg/N ratios) we conclude that these concentration increases are dominated by additional atmospheric deposition retained in the decomposing plant material while exposed to the environment rather than by organic C losses during decomposition. The large majority of total ecosystem mercury, up to 98 percent, however, is sequestered belowground in the soils. Soil Hg accumulation across all sites is greatly determined by the availability of organic matter in these systems, with soil C and soil N explaining more than 90 percent of the variability in observed soil Hg stocks. Our results suggest that the availability of soil organic matter is the main determinant for retention of atmospheric inputs in soils and hence in terrestrial ecosystems. Ecosystem structure and soil organic accumulation hence determine the resilience of Hg in terrestrial ecosystems with important implication for the stability and runoff of atmospheric Hg deposition to surrounding waterbodies.

  20. XUV-Exposed, Non-Hydrostatic Hydrogen-Rich Upper Atmospheres of Terrestrial Planets. Part I: Atmospheric Expansion and Thermal Escape

    PubMed Central

    Lammer, Helmut; Odert, Petra; Kulikov, Yuri N.; Kislyakova, Kristina G.; Khodachenko, Maxim L.; Güdel, Manuel; Hanslmeier, Arnold; Biernat, Helfried

    2013-01-01

    Abstract The recently discovered low-density “super-Earths” Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent the most likely known planets that are surrounded by dense H/He envelopes or contain deep H2O oceans also surrounded by dense hydrogen envelopes. Although these super-Earths are orbiting relatively close to their host stars, they have not lost their captured nebula-based hydrogen-rich or degassed volatile-rich steam protoatmospheres. Thus, it is interesting to estimate the maximum possible amount of atmospheric hydrogen loss from a terrestrial planet orbiting within the habitable zone of late main sequence host stars. For studying the thermosphere structure and escape, we apply a 1-D hydrodynamic upper atmosphere model that solves the equations of mass, momentum, and energy conservation for a planet with the mass and size of Earth and for a super-Earth with a size of 2 REarth and a mass of 10 MEarth. We calculate volume heating rates by the stellar soft X-ray and extreme ultraviolet radiation (XUV) and expansion of the upper atmosphere, its temperature, density, and velocity structure and related thermal escape rates during the planet's lifetime. Moreover, we investigate under which conditions both planets enter the blow-off escape regime and may therefore experience loss rates that are close to the energy-limited escape. Finally, we discuss the results in the context of atmospheric evolution and implications for habitability of terrestrial planets in general. Key Words: Stellar activity—Low-mass stars—Early atmospheres—Earth-like exoplanets—Energetic neutral atoms—Ion escape—Habitability. Astrobiology 13, 1011–1029. PMID:24251443

  1. Global and Regional Constraints on Exchanges of CO2 Between the Atmosphere and Terrestrial Biosphere

    NASA Astrophysics Data System (ADS)

    Piper, S. C.

    2001-12-01

    The vigorous atmospheric circulation rapidly mixes CO2 that is exchanged with the terrestrial biosphere and oceans. Therefore, at time scales greater than 1 year, the approximate interhemispheric exchange time of the atmosphere, an average of CO2 measurements from a network of surface stations can be used to accurately determine the global net change in atmospheric CO2. By subtracting CO2 produced by fossil fuel combustion, which is well characterized by national statistics, the global the sum of terrestrial biospheric and oceanic net fluxes, here termed the "nonfossil" CO2 flux, can also be accurately determined. The nonfossil CO2 flux averaged -2.1+/-0.3 PgC/yr and -3.2+/-0.4 PgC/yr in the 1980s and 1990s respectively (negative denotes out of the atmosphere), and varied in annual average from about 0 to -4 PgC/yr over these two decades. Two primary methods have been used to further partition the nonfossil CO2 flux between land and oceans: the O2 and 13C/12C methods, which rely, respectively, on measurements of atmospheric O2 (actually O2/N2 for technical reasons) and of the 13C/12C ratio of CO2. Burning of fossil fuel consumes atmospheric O2 and releases CO2 with a 13C/12C ratio lower than that of atmospheric CO2 whereas uptake of CO2 by terrestrial plants releases O2, and increases the atmospheric 13C/12C ratio owing to the preferential assimilation of 12CO2 relative to 13CO2. In contrast, the uptake of CO2 by the oceans has little effect on either the atmospheric O2 or 13C/12C ratio. Therefore, the net CO2 uptake or release from the terrestrial biosphere can be calculated in either method by subtracting the change owing to fossil fuel emissions from the measured change in the atmosphere, utilizing known stoichiometric ratios of O2 and CO2 in the O2 method, and isotopic fractionation factors in the 13C/12C method. Currently, the O2 method gives a net global terrestrial biospheric CO2 flux of -0.2+/-0.7 PgC/yr and -1.4+/-0.7 PgC/yr for the 1980s and the 1990s, respectively. Both the O2 and 13C/12C methods have complications and limitations that will be discussed. To partition the global biospheric flux further to zonal or regional detail or to shorter time steps, atmospheric models are required to simulate the transport of tracer from source regions to individual stations where air is sampled. An ongoing collaborative project to compare atmospheric models has highlighted significant differences in transport characteristics, mainly owing to differences in how the boundary layer is modeled. Accordingly, a recent compilation of model calculations showed a wide range of estimates for the tropical biosphere, from a significant release of CO2 to an uptake over recent decades; however, the calculations showed reasonable agreement on a significant northern biospheric sink. Fluxes of biospheric CO2 can be determined accurately at the global scale as well as at individual sites. An ingenious blend of observations and models will be required to bridge the gap between these two extreme spatial scales, and thereby gain an understanding sufficient to predict the influence of the terrestrial biosphere on variations in atmospheric CO2.

  2. Reconciling atmospheric temperatures in the early Archean

    NASA Astrophysics Data System (ADS)

    Pope, E. C.; Rosing, M.; Bird, D. K.; Albarede, F.

    2012-12-01

    Average surface temperatures of Earth in the Archean remain unresolved despite decades of diverse approaches to the problem. As in the present, early Earth climates were complex systems dependent on many variables. With few constraints on such variables, climate models must be relatively simplistic, and consider only one or two factors that drive Archean climate (e.g. a fainter young sun, a low albedo, the extent and effect of cloud cover, or the presence and abundance of a wide array of greenhouse and icehouse gasses). Compounded on the limitations of modeling is the sparse and often ambiguous Archean rock record. The goal of this study is to compile and reconcile Archean geologic and geochemical features that are in some way controlled by surface temperature and/or atmospheric composition, so that at the very least paleoclimate models can be checked by physical limits. Data used to this end include the oxygen isotope record of chemical sediments and ancient ocean crust, chemical equilibria amongst primary phases in banded iron formations (BIFs), sedimentary features indicative of temperate or glacial environments, and paleosol indicators of atmospheric CO2. Further, we explore the extent to which hydrogen isotopes contribute to the geologic record as a signal for glaciations, continental growth and atmospheric methane levels. Oceanic serpentinites and subduction-related volcanic and hydrothermal environments obtain their hydrogen isotope signature from seawater, and thus may be used to calculate secular variation in ?DSEAWATER which may fluctuate significantly due to hydrogen escape, continental growth and large-scale glaciation events. Further, ancient records of low-?D meteoric fluids signal both cooler temperatures and the emergence of large continents (increasing the effects of continental weathering on climate). Selective alteration of ?D in Isua rocks to values of -130 to -100‰ post-dates ca. 3.55Ga Ameralik dikes, but may be associated with a poorly defined 2.6-2.8Ga metamorphic event that is coincident with the amalgamation of the "Kenorland supercontinent."

  3. 3D-radiative transfer in terrestrial atmosphere: An efficient parallel numerical procedure

    Microsoft Academic Search

    L. P. Bass; T. A. Germogenova; O. V. Nikolaeva; A. A. Kokhanovsky; V. S. Kuznetsov

    2003-01-01

    Light propagation and scattering in terrestrial atmosphere is usually studied in the framework of the 1D radiative transfer theory [1]. However, in reality particles (e.g., ice crystals, solid and liquid aerosols, cloud droplets) are randomly distributed in 3D space. In particular, their concentrations vary both in vertical and horizontal directions. Therefore, 3D effects influence modern cloud and aerosol retrieval procedures,

  4. Evaluation of atmospheric aerosol and tropospheric ozone effects on global terrestrial ecosystem carbon dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Min

    The increasing human activities have produced large amounts of air pollutants ejected into the atmosphere, in which atmospheric aerosols and tropospheric ozone are considered to be especially important because of their negative impacts on human health and their impacts on global climate through either their direct radiative effect or indirect effect on land-atmosphere CO2 exchange. This dissertation dedicates to quantifying and evaluating the aerosol and tropospheric ozone effects on global terrestrial ecosystem dynamics using a modeling approach. An ecosystem model, the integrated Terrestrial Ecosystem Model (iTem), is developed to simulate biophysical and biogeochemical processes in terrestrial ecosystems. A two-broad-band atmospheric radiative transfer model together with the Moderate-Resolution Imaging Spectroradiometer (MODIS) measured atmospheric parameters are used to well estimate global downward solar radiation and the direct and diffuse components in comparison with observations. The atmospheric radiative transfer modeling framework were used to quantify the aerosol direct radiative effect, showing that aerosol loadings cause 18.7 and 12.8 W m -2 decrease of direct-beam Photosynthetic Active Radiation (PAR) and Near Infrared Radiation (NIR) respectively, and 5.2 and 4.4 W m -2 increase of diffuse PAR and NIR, respectively, leading to a total 21.9 W m-2 decrease of total downward solar radiation over the global land surface during the period of 2003-2010. The results also suggested that the aerosol effect may be overwhelmed by clouds because of the stronger extinction and scattering ability of clouds. Applications of the iTem with solar radiation data and with or without considering the aerosol loadings shows that aerosol loading enhances the terrestrial productions [Gross Primary Production (GPP), Net Primary Production (NPP) and Net Ecosystem Production (NEP)] and carbon emissions through plant respiration (RA) in global terrestrial ecosystems over the period of 2003-2010. Ecosystem heterotrophic respiration (RH) was negatively affected by the aerosol loading. These results support previous conclusions of the advantage of aerosol light scattering effect on plant productions in other studies but suggest there is strong spatial variation. This study finds indirect aerosol effects on terrestrial ecosystem carbon dynamics through affecting plant phenology, thermal and hydrological environments. All these evidences suggested that the aerosol direct radiative effect on global terrestrial ecosystem carbon dynamics should be considered to better understand the global carbon cycle and climate change. An ozone sub-model is developed in this dissertation and fully coupled with iTem. The coupled model, named iTemO3 considers the processes of ozone stomatal deposition, plant defense to ozone influx, ozone damage and plant repairing mechanism. By using a global atmospheric chemical transport model (GACTM) estimated ground-level ozone concentration data, the model estimated global annual stomatal ozone deposition is 234.0 Tg O3 yr-1 and indicates which regions have high ozone damage risk. Different plant functional types, sunlit and shaded leaves are shown to have different responses to ozone. The model predictions suggest that ozone has caused considerable change on global terrestrial ecosystem carbon storage and carbon exchanges over the study period 2004-2008. The study suggests that uncertainty of the key parameters in iTemO3 could result in large errors in model predictions. Thus more experimental data for better model parameterization is highly needed.

  5. Net primary production of terrestrial ecosystems in China and its equilibrium response to changes in climate and atmospheric CO? concentration

    E-print Network

    Xiao, Xiangming.; Melillo, Jerry M.; Kicklighter, David W.; Pan, Yude.; McGuire, A. David.; Helfrich III, J.V.K.

    The Terrestrial Ecosystem Model (TEM, version 4.0) was used to estimate net primary production (NPP) in China for contemporary climate and NPP responses to elevated CO? and climate changes projected by three atmospheric ...

  6. A terrestrial Eocene stack: tying terrestrial lake ecology to marine carbon cycling through the Early Eocene Climatic Optimum

    NASA Astrophysics Data System (ADS)

    Grogan, D. S.; Whiteside, J. H.; Musher, D.; Rosengard, S. Z.; Vankeuren, M. A.; Pancost, R. D.

    2010-12-01

    The lacustrine Green River Formation is known to span ?15 million years through the early-middle Eocene, and recent work on radioisotopic dating has provided a framework on which to build ties to the orbitally-tuned marine Eocene record. Here we present a spliced stack of Fischer assay data from drilled cores of the Green River Formation that span both an East-West and a North-South transect of the Uinta Basin of Utah. Detailed work on two cores demonstrate that Fischer assay measurements covary with total organic carbon and bulk carbon isotopes, allowing us to use Fisher assay results as a representative carbon cycling proxy throughout the stack. We provide an age model for this core record by combining radioisotopic dates of tuff layers with frequency analysis of Fischer assay measurements. Identification of orbital frequencies tied directly to magnetochrons through radioisotopic dates allows for a direct comparison of the terrestrial to the marine Eocene record. Our analysis indicates that the marker beds used to correlate the stack cores represent periods of enhanced lake productivity and extreme carbon burial; however, unlike the hyperthermal events that are clearly marked in the marine Eocene record, the hydrocarbon-rich "Mahogany Bed" period of burial does not correspond to a clear carbon isotope excursion. This suggests that the terrestrial realm may have experienced extreme ecological responses to relatively small perturbations in the carbon cycle during the Early Eocene Climatic Optimum. To investigate the ecological responses to carbon cycle perturbations through the hydrocarbon rich beds, we analyzed a suite of microbial biomarkers, finding evidence for cyanobacteria, dinoflagellates, and potentially green sulfur bacteria. These taxa indicate fluctuating oxic/anoxic conditions in the lake during abrupt intervals of carbon burial, suggesting a lake biogeochemical regime with no modern analogues.

  7. Trophic network models explain instability of Early Triassic terrestrial communities.

    PubMed

    Roopnarine, Peter D; Angielczyk, Kenneth D; Wang, Steve C; Hertog, Rachel

    2007-09-01

    Studies of the end-Permian mass extinction have emphasized potential abiotic causes and their direct biotic effects. Less attention has been devoted to secondary extinctions resulting from ecological crises and the effect of community structure on such extinctions. Here we use a trophic network model that combines topological and dynamic approaches to simulate disruptions of primary productivity in palaeocommunities. We apply the model to Permian and Triassic communities of the Karoo Basin, South Africa, and show that while Permian communities bear no evidence of being especially susceptible to extinction, Early Triassic communities appear to have been inherently less stable. Much of the instability results from the faster post-extinction diversification of amphibian guilds relative to amniotes. The resulting communities differed fundamentally in structure from their Permian predecessors. Additionally, our results imply that changing community structures over time may explain long-term trends like declining rates of Phanerozoic background extinction. PMID:17609191

  8. Terrestrial ecosystems response to future changes in climate and atmospheric CO2 concentration

    NASA Astrophysics Data System (ADS)

    Arora, V. K.; Boer, G. J.

    2014-08-01

    The response of the terrestrial carbon cycle to future changes in climate and atmospheric CO2 is assessed by analysing simulation results for the 2006-2100 period made with the second generation Canadian Earth system model (CanESM2) for the RCP 2.6, RCP 4.5 and RCP 8.5 climate change scenarios. Our interest is in the extent to which global terrestrial carbon pools and sinks, in particular those of the Amazonian region, are vulnerable to the adverse effects of climate change. CanESM2 results indicate that land remains an overall sink of atmospheric carbon for the 2006-2100 period. The net carbon uptake by land in response to changes in climate and atmospheric CO2 is close to 20, 80 and 140 Pg C for the RCP 2.6, 4.5 and 8.5 scenarios, respectively. The latitudinal structure of future atmosphere-land CO2 flux remains similar to that observed for the historical period with northern mid- to high-latitude regions gaining carbon from the atmosphere while the tropics remain either carbon neutral or a modest source of atmospheric carbon depending on scenario. These changes occur in conjunction with simulated precipitation and soil moisture increases over northern mid- and high-latitude land regions and precipitation and soil moisture decreases over the South American continent in all scenarios. Compared to other regions of the globe, which are either carbon sinks or near neutral, the Amazonian region is simulated to be a net source of carbon during the 21st century. Moreover, and unexpectedly, the rate of carbon loss to the atmosphere from the Amazonian region is largely independent of the differences between the three scenarios considered.

  9. The Terrestrial Planets Large Bodies

    E-print Network

    Gaudi, B. Scott

    : Greenhouse Effect: Solar heating & atmospheric cooling balance Helps determine if H2O is liquid, ice atmosphere. May have had early oceans that evaporated resulting in a Runaway Greenhouse Effect. Gravity elements. #12;The evolution of Terrestrial Planet atmospheres is driven by three primary effects

  10. Optimization of a prognostic biosphere model in atmospheric CO2 variability and terrestrial biomass

    NASA Astrophysics Data System (ADS)

    Saito, M.; Ito, A.; Maksyutov, S.

    2013-08-01

    This study investigated the capacity of a prognostic biosphere model to simulate global vegetation carbon dynamics and the variability in atmospheric CO2 concentrations under the current environmental conditions. Global data sets of atmospheric CO2 concentrations and terrestrial vegetation compositions of the aboveground biomass and net primary productivity (NPP) were assimilated into the biosphere model using an inverse modeling method combined with an atmospheric transport model. In this process, the optimal physiological parameters of the biosphere model were estimated by minimizing the misfit between the observed and modeled values, and acceptable parameters with various values were generated among the biome types. The model with the optimized parameters corresponded to the observed seasonal variations in the CO2 concentration, especially in the Northern Hemisphere where there are abundant observation stations, although the annual amplitudes were overestimated at a few stations. In simulating the mean annual aboveground biomass and NPP, the model also produced moderate estimates of the mean magnitudes and probability distributions for each biome. However, the model worked less efficiently in simulating the terrestrial vegetation compositions in some grids. These misfits suggest that some additional information about the disturbance and seasonal variability of the physiological parameters is required to improve the performance of the simulation model.

  11. Sulfur Chemistry in the Early and Present Atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.; Summers, M. E.

    2011-01-01

    Atmospheric sulfur species resulting from volcanic emissions impact the composition and chemistry of the atmosphere, impact the climate, and hence, the habitability of Mars and impact the mineralogy and composition of the surface of Mars. The geochemical/ photochemical cycling of sulfur species between the interior (via volcanism), the atmosphere (atmospheric photochemical and chemical processes) and the deposition of sulfuric acid on the surface of Mars is an important, but as yet poorly understood geochemical/ photochemical cycle on Mars. There is no observational evidence to indicate that Mars is volcanically active at the present time, however, there is strong evidence that volcanism was an important and widespread process on early Mars. The chemistry and photochemistry of sulfur species in the early and present atmosphere of Mars will be assessed using a one-dimensional photochemical model. Since it is generally assumed that the atmosphere of early Mars was significantly denser than the present 6-millibar atmosphere, photochemical calculations were performed for the present atmosphere and for the atmosphere of early Mars with assumed surface pressures of 60 and 350-millibars, where higher surface pressure resulted from enhanced atmospheric concentrations of carbon dioxide (CO2). The following sections include the results of earlier modeling studies, a summary of the one-dimensional photochemical model used in this study, a summary of the photochemistry and chemistry of sulfur species in the atmosphere of Mars and some of the results of the calculations.

  12. Venus as illustration of the importance of atmospheric evolution when modeling terrestrial planets and their surface conditions

    NASA Astrophysics Data System (ADS)

    Gillmann, C.; Tackley, P. J.; Golabek, G.

    2012-12-01

    The best way we can study what determines habitability is by comparing the one planet we know shelters life to other bodies. As extrasolar super-Earths will be found, we'll have access to more planetary samples, starting with their atmosphere. Taking our solar system as pattern, CO2 atmospheres might be common. Therefore, we use Venus to test our numerical modeling of the evolution of the atmosphere of terrestrial planets, as an intermediary between life-sustaining Earth and yet to be discovered exoplanets. We propose to investigate the evolution of the atmosphere and surface conditions on Venus. Here, we focus on mechanisms that deplete or replenish the atmosphere: volcanic degassing and atmospheric escape. These processes are linked together to obtain a coupled model, using retroaction of the atmosphere on the mantle. We study potential divergent evolutions this could cause. Two aspects of the atmospheric escape are taken into account. During early evolution, hydrodynamic escape is dominant. We use a model developed to take into account the linked escape of Hydrogen and Oxygen (Gillmann et al., 2009). A significant portion of the early atmosphere can be removed this way. For later evolution, we focus on non-thermal escape, as observed by the ASPERA instrument and modeled in various recent numerical studies. Post 4 Ga escape is low. Water escapes moderately, while we are not able to detect the present-day escape of CO2. The atmosphere is replenished by volcanic degassing, bringing volatiles from the mantle to the surface. Volcanic activity is obtained by adapting the highly advanced StagYY mantle dynamics model (Tackley, 2008) for Venus. Volatile fluxes are estimated for different mantle compositions and partitioning ratios. Surface conditions are estimated by tracking the amount of CO2 and water in the atmosphere and computing the surface temperature with a gray radiative-convective atmosphere model. These surface conditions in turn act as a boundary condition for the mantle dynamic model and have an influence on convection, volcanism and subsequent degassing. Our results show that we are able to obtain a Venus-like behavior for the solid planet, with resurfacing events which constitute an efficient way of losing Venus' internal heat. The atmosphere shows several interesting features. We are able to create evolution leading to present conditions. CO2 pressure seems unlikely to vary much over the history of the planet, only slightly increasing due to degassing. A late build-up of the atmosphere with several resurfacing events seems unlikely. On the other hand, water pressure is strongly sensitive to volcanic activity and varies rapidly. This leads to variations in surface temperatures of up to 200K, which have been identified to have an effect on volcanic activity. While a positive feedback (increasing atmosphere temperature leading to increasing mantle temperatures and melting) is not immediately apparent, we observe a clear link between temperature changes and volcanic spikes, in particular a strong correlation between large temperature drops and increased volcanism. Mobilization of the upper layers occurs, which imply that our coupling is not complete without taking into account rehydratation of the mantle. This depends on the surface alteration processes and could have important effects.

  13. CO2 greenhouse in the early martian atmosphere: SO2 inhibits condensation

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.; Nair, H.; Gerstell, M. F.

    1997-01-01

    Many investigators of the early martian climate have suggested that a dense carbon dioxide atmosphere was present and warmed the surface above the melting point of water (J.B. Pollack, J.F. Kasting, S.M. Richardson, and K. Poliakoff 1987. Icarus 71, 203-224). However, J.F. Kasting (1991. Icarus 94, 1-13) pointed out that previous thermal models of the primitive martian atmosphere had not considered the condensation of CO2. When this effect was incorporated, Kasting found that CO2 by itself is inadequate to warm the surface. SO2 absorbs strongly in the near UV region of the solar spectrum. While a small amount of SO2 may have a negligible effect by itself on the surface temperature, it may have significantly warmed the middle atmosphere of early Mars, much as ozone warms the terrestrial stratosphere today. If this region is kept warm enough to inhibit the condensation of CO2, then CO2 remains a viable greenhouse gas. Our preliminary radiative modeling shows that the addition of 0.1 ppmv of SO2 in a 2 bar CO2 atmosphere raises the temperature of the middle atmosphere by approximately 10 degrees, so that the upper atmosphere in a 1 D model remains above the condensation temperature of CO2. In addition, this amount of SO2 in the atmosphere provides an effective UV shield for a hypothetical biosphere on the martian surface.

  14. Chernobyl radionuclides in the environment: Tracers for the tight coupling of atmospheric, terrestrial, and aquatic geochemical processes

    Microsoft Academic Search

    P. H. Santschl; Silvia Bollhalder; Klaus Farrenkothen; Alfred Lueck; Stefan Zingg; Michael Sturm

    1988-01-01

    Observations of the temporal trend in concentrations of Chernobyl radionuclides in atmospheric, terrestrial, and aquatic reservoirs near Duebendorf (Zurich) aided in quantifying fluxes and transfer velocities from one reservoir to another. Radionuclide dry and wet deposition rates and velocities from the atmosphere, washout from the catchment basins into surface waters, and deposition rates and mechanisms in lakes were determined. The

  15. Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars

    PubMed Central

    Shaheen, R.; Abramian, A.; Horn, J.; Dominguez, G.; Sullivan, R.; Thiemens, Mark H.

    2010-01-01

    The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess 17O (0.4–3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O3 reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

  16. Understanding the early Mesozoic world: New geochronological data from terrestrial and marine strata

    NASA Astrophysics Data System (ADS)

    Mundil, Roland; Irmis, Randall B.; Ickert, Ryan B.

    2013-04-01

    The first ~50 Ma of the Mesozoic (the Triassic Period) are marked by two major mass extinctions at the end-Permian and end-Triassic, extensive flood volcanic events (the Siberian Traps and the Central Atlantic Magmatic Province), perturbations of the ocean chemistry, paleoenvironmental changes in a greenhouse world and the origin of modern terrestrial ecosystems. Marine records of events leading to the end-Permian extinction as well as subsequent recovery during the Early and Middle Triassic are now well understood in terms of their relative and absolute timing, mainly due to significant advances in both the quantity and quality of geochronological data. This includes a detailed understanding of the Middle and end-Permian extinction events and their potential causes, their aftermath, and also the timing of large scale perturbations of the global carbon cycle in the Early Triassic. For the remaining ~30 Ma of the Triassic, however, there was until recently virtually no chronostratigraphic framework, and hence there is a major lag in our understanding of major events such as the origin and early diversification of dinosaurs, major reef building episodes in marine ecosystems, paleoenvironmental changes (e.g., the Carnian Pluvial Event), and a large extraterrestrial bolide impact (the Manicouagan impact). In absence of high-resolution radioisotopic ages, assumptions about causal inference and the role of these events, remain poorly constrained. We have therefore started to build a chronostratigraphic framework by applying U-Pb CA-TIMS analyses to zircon from primary and redeposited volcanic strata within both marine and terrestrial sequences of Late Triassic age. In particular, the potential of geochronological techniques applied to redeposited volcanic layers has long been ignored because the time lag between zircon crystallization and deposition is unknown; however, our initial results calibrating terrestrial sequences in North and South America are very promising and many of the obtained maximum ages are in agreement with stratigraphic order. Our new marine ages support the hypothesis of a long Norian Stage (~20 Ma), and new data suggest a wholly Norian age for the fossiliferous terrestrial Chinle Formation in the southwestern US. Thus, previous correlations based on terrestrial biostratigraphy with deposits in South American sequences are now thought to be flawed, suggesting that the rise of dinosaurs was diachronous, and occurred later in North America than in South America. Further complementary geochronological analyses from marine sequences are currently underway and are aimed at correlating and understanding key events and processes that are recorded both marine and terrestrial sedimentary archives of Late Triassic age.

  17. Constraining terrestrial ecosystem CO2 fluxes by integrating models of biogeochemistry and atmospheric transport and data of surface carbon fluxes and atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Zhuang, Q.; Henze, D.; Bowman, K.; Chen, M.; Liu, Y.; He, Y.; Matsueda, H.; Machida, T.; Sawa, Y.; Oechel, W.

    2014-09-01

    Regional net carbon fluxes of terrestrial ecosystems could be estimated with either biogeochemistry models by assimilating surface carbon flux measurements or atmospheric CO2 inversions by assimilating observations of atmospheric CO2 concentrations. Here we combine the ecosystem biogeochemistry modeling and atmospheric CO2 inverse modeling to investigate the magnitude and spatial distribution of the terrestrial ecosystem CO2 sources and sinks. First, we constrain a terrestrial ecosystem model (TEM) at site level by assimilating the observed net ecosystem production (NEP) for various plant functional types. We find that the uncertainties of model parameters are reduced up to 90% and model predictability is greatly improved for all the plant functional types (coefficients of determination are enhanced up to 0.73). We then extrapolate the model to a global scale at a 0.5° × 0.5° resolution to estimate the large-scale terrestrial ecosystem CO2 fluxes, which serve as prior for atmospheric CO2 inversion. Second, we constrain the large-scale terrestrial CO2 fluxes by assimilating the GLOBALVIEW-CO2 and mid-tropospheric CO2 retrievals from the Atmospheric Infrared Sounder (AIRS) into an atmospheric transport model (GEOS-Chem). The transport inversion estimates that: (1) the annual terrestrial ecosystem carbon sink in 2003 is -2.47 Pg C yr-1, which agrees reasonably well with the most recent inter-comparison studies of CO2 inversions (-2.82 Pg C yr-1); (2) North America temperate, Europe and Eurasia temperate regions act as major terrestrial carbon sinks; and (3) The posterior transport model is able to reasonably reproduce the atmospheric CO2 concentrations, which are validated against Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) CO2 concentration data. This study indicates that biogeochemistry modeling or atmospheric transport and inverse modeling alone might not be able to well quantify regional terrestrial carbon fluxes. However, combining the two modeling approaches and assimilating data of surface carbon flux as well as atmospheric CO2 mixing ratios might significantly improve the quantification of terrestrial carbon fluxes.

  18. Studies of volatiles and organic materials in early terrestrial and present-day outer solar system environments

    NASA Technical Reports Server (NTRS)

    Sagan, Carl; Thompson, W. Reid; Chyba, Christopher F.; Khare, B. N.

    1991-01-01

    A review and partial summary of projects within several areas of research generally involving the origin, distribution, chemistry, and spectral/dielectric properties of volatiles and organic materials in the outer solar system and early terrestrial environments are presented. The major topics covered include: (1) impact delivery of volatiles and organic compounds to the early terrestrial planets; (2) optical constants measurements; (3) spectral classification, chemical processes, and distribution of materials; and (4) radar properties of ice, hydrocarbons, and organic heteropolymers.

  19. Journal of the Atmospheric Sciences EARLY ONLINE RELEASE

    E-print Network

    Pauluis, Olivier M.

    Journal of the Atmospheric Sciences EARLY ONLINE RELEASE This is a preliminary PDF of the author circulation on dry and moist isentropes. It is further tested10 using four reanalysis datasets: the ERA

  20. On the Climatic Impact of CO2 Ice Particles in Atmospheres of Terrestrial Exoplanets

    NASA Astrophysics Data System (ADS)

    Kitzmann, D.; Patzer, A. B. C.; Rauer, H.

    2014-04-01

    Clouds play a significant role for the energy budget in planetary atmospheres. They can scatter incident stellar radiation back to space, effectively cooling the surface of terrestrial planets. On the other hand, they may contribute to the atmospheric greenhouse effect by trapping outgoing thermal radiation. For exoplanets near the outer boundary of the habitable zone, condensation of CO2 can occur due to the low atmospheric temperatures. These CO2 ice clouds may play an important role for the surface temperature and, therefore, for the question of habitability of those planets. However, the optical properties of CO2 ice crystals differ significantly from those of water droplets or water ice particles. Except for a small number of strong absorption bands, they are almost transparent with respect to absorption. Instead, they are highly effective scatterers at long and short wavelengths. Therefore, the climatic effect of a CO2 ice cloud will depend on how much incident stellar radiation is scattered to space in comparison to the amount of thermal radiation scattered back towards the planetary surface. This contribution aims at the potential greenhouse effect of CO2 ice particles. Their scattering and absorption properties are calculated for assumed particle size distributions with different effective radii and particle densities. An accurate radiative transfer model is used to determine the atmospheric radiation field affected by such CO2 particles. These results are compared to less detailed radiative transfer schemes employed in previous studies.

  1. Early Paleogene evolution of terrestrial climate in the SW Pacific, Southern New Zealand

    NASA Astrophysics Data System (ADS)

    Pancost, Richard D.; Taylor, Kyle W. R.; Inglis, Gordon N.; Kennedy, Elizabeth M.; Handley, Luke; Hollis, Christopher J.; Crouch, Erica M.; Pross, Jörg; Huber, Matthew; Schouten, Stefan; Pearson, Paul N.; Morgans, Hugh E. G.; Raine, J. Ian

    2013-12-01

    We present a long-term record of terrestrial climate change for the Early Paleogene of the Southern Hemisphere that complements previously reported marine temperature records. Using the MBT'-CBT proxy, based on the distribution of soil bacterial glycerol dialkyl glycerol tetraether lipids, we reconstructed mean annual air temperature (MAT) from the Middle Paleocene to Middle Eocene (62-42 Ma) for southern New Zealand. This record is consistent with temperature estimates derived from leaf fossils and palynology, as well as previously published MBT'-CBT records, which provides confidence in absolute temperature estimates. Our record indicates that through this interval, temperatures were typically 5°C warmer than those of today at such latitudes, with more pronounced warming during the Early Eocene Climate Optimum (EECO; ˜50 Ma) when MAT was ˜20°C. Moreover, the EECO MATs are similar to those determined for Antarctica, with a weak high-latitude terrestrial temperature gradient (˜5°C) developing by the Middle Eocene. We also document a short-lived cooling episode in the early Late Paleocene when MAT was comparable to present. This record corroborates the trends documented by sea surface temperature (SST) proxies, although absolute SSTs are up to 6°C warmer than MATs. Although the high-calibration error of the MBT'-CBT proxy dictates caution, the good match between our MAT results and modeled temperatures supports the suggestion that SST records suffer from a warm (summer?) bias, particularly during times of peak warming.

  2. Climate and atmospheric drivers of historical terrestrial carbon uptake in the province of British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Peng, Y.; Arora, V. K.; Kurz, W. A.; Hember, R. A.; Hawkins, B.; Fyfe, J. C.; Werner, A. T.

    2013-08-01

    The impacts of climate change and increasing atmospheric CO2 concentration on the terrestrial uptake of carbon dioxide since 1900 in the Canadian province of British Columbia are estimated using the process-based Canadian Terrestrial Ecosystem Model (CTEM). Model simulations show that these two factors yield a carbon uptake of around 44 g C m-2 yr-1, during the 1980s and 1990s, and continuing into 2000s, compared to pre-industrial conditions. The increased carbon uptake translates into an increased sink of 41 Tg C yr-1, when multiplied with the 944 700 km2 area of the province. About three-quarters of the simulated sink enhancement in our study is attributed to changing climate, and the rest is attributed to increase in CO2 concentration. The model response to changing climate and increasing CO2 is corroborated by comparing simulated stem wood growth rates with ground-based measurements from inventory plots in coastal British Columbia. The simulated sink is not an estimate of the net carbon balance because the effect of harvesting and insect disturbances is not considered.

  3. Paleolimnological archives of environmental change in aquatic, terrestrial, and atmospheric systems

    SciTech Connect

    Fritz, S.C.; Engstrom, D.R. (Univ. of Minnesota, Minneapolis (United States))

    1993-06-01

    Lake sediments accumulate material derived from the atmosphere, the lake catchment, and the lake itself, and these materials can be used to infer the history of aquatic and terrestrial ecosystems, the climate system, and global biogeochemical cycling. Several case-studies will be presented to discuss the reconstruction of environmental variability from the paleolimnological record including studies of (1) Climate history: Closed-basin lakes are sensitive recorders of changes in the hydrologic budget and are used in and semi-arid regions to assess patterns of long- and short-term variability in moisture availability; (2) Biogeochemical cycling/pollution history: Basin-wide measurement of mercury accumulation in lake sediments is used to estimate modem and pre-industrial rates of mercury deposition and the contribution of global vs regional sources; and (3) Acidification history: Lake-pH is reconstructed from aquatic microfossils and correlated with changes in pollutant deposition and terrestrial vegetation to evaluate the extent, timing, and causes of acidification.

  4. Optimization of a prognostic biosphere model for terrestrial biomass and atmospheric CO2 variability

    NASA Astrophysics Data System (ADS)

    Saito, M.; Ito, A.; Maksyutov, S.

    2014-08-01

    This study investigates the capacity of a prognostic biosphere model to simulate global variability in atmospheric CO2 concentrations and vegetation carbon dynamics under current environmental conditions. Global data sets of atmospheric CO2 concentrations, above-ground biomass (AGB), and net primary productivity (NPP) in terrestrial vegetation were assimilated into the biosphere model using an inverse modeling method combined with an atmospheric transport model. In this process, the optimal physiological parameters of the biosphere model were estimated by minimizing the misfit between observed and modeled values, and parameters were generated to characterize various biome types. Results obtained using the model with the optimized parameters correspond to the observed seasonal variations in CO2 concentration and their annual amplitudes in both the Northern and Southern Hemispheres. In simulating the mean annual AGB and NPP, the model shows improvements in estimating the mean magnitudes and probability distributions for each biome, as compared with results obtained using prior simulation parameters. However, the model is less efficient in its simulation of AGB for forest type biomes. This misfit suggests that more accurate values of input parameters, specifically, grid mean AGB values and seasonal variabilities in physiological parameters, are required to improve the performance of the simulation model.

  5. Terrestrial Gamma-Ray Flashes, Relativistic Runaway, and High-Energy Radiation in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Smith, David M.

    2009-04-01

    High energy radiation from tens of keV to tens of MeV in energy, the transition region from x-rays to gamma rays, has been observed in association with high electric fields in air in many contexts: from the ground, associated with thunderstorms and with individual flashes of natural and rocket-triggered lightning [1, 2, 3, 4, 5, 6, 7, 8] from sparks in the laboratory [9, 10, 11, 12], from Earth orbit in the form of millisecond Terrestrial Gamma-ray Flashes (TGFs) [13, 14], and at intermediate altitudes from aircraft and balloons [15, 16, 17, 18, 19]. The gamma radiation in all cases is almost certainly bremsstrahlung generated by the collision of accelerated electrons with nuclei in the atmosphere. The penetrating gamma-rays can provide a mechanism for coupling between the troposphere, mesosphere, ionosphere and magnetosphere in the form of energetic particles and ionization.

  6. Terrestrial microorganisms at an altitude of 20,000 m in Earth's atmosphere

    USGS Publications Warehouse

    Griffin, Dale W.

    2004-01-01

    A joint effort between the U.S. Geological Survey's (USGS) Global Desert Dust and NASA's Stratospheric and Cosmic Dust Programs identified culturable microbes from an air sample collected at an altitude of 20,000 m. A total of 4 fungal (Penicillium sp.) and 71 bacteria colonyforming units (70 colonies of Bacillus luciferensis believed to have originated from a single cell collected at altitude and one colony of Bacillus sphaericus) were enumerated, isolated and identified using a morphological key and 16S rDNA sequencing respectively. All of the isolates identified were sporeforming pigmented fungi or bacteria of terrestrial origin and demonstrate that the presence of viable microorganisms in Earth's upper atmosphere may not be uncommon.

  7. Exploring the Sensitivity of Terrestrial Ecosystems and Atmospheric Exchange of CO2 to Global Environmental Factors

    NASA Astrophysics Data System (ADS)

    Jain, A. K.; Meiyappan, P.; Song, Y.; Barman, R.

    2011-12-01

    This presentation explores the sensitivity of terrestrial ecosystems and atmospheric exchange of carbon to global environmental factors to advance our understanding of uncertainty in CO2 projections. We use a land surface model, the Integrated Science Assessment Model (ISAM) recently coupled into the NCAR Community Earth System Model (CESM1) framework to evaluate ecosystem variability due to climatic and anthropogenic factors. The factors considered here include climate change, increasing ambient CO2 concentrations, anthropogenic nitrogen deposition, and land use change (LUC) activities such as clearing of land for agriculture, pasture, and wood harvest. Each factor has a potential to influence the net ecosystem exchange (NEE) of CO2. Using the ISAM-CESM modeling framework, we evaluate the individual and concurrent effects of all these environmental factors on the terrestrial NEE over the 20th century and the 21st century. The ISAM biogeochemical cycles consist of fully prognostic carbon and nitrogen dynamics associated with changes in land cover, litter decomposition, and soil organic matter. The ISAM biophysical model accounts for water and energy processes in the vegetation and soil column, integrated over a time step of 30 minutes. The newly available CRU-NCEP climate forcing data (1850-2010, 0.5ox0.5o spatial resolution) will be used for the historical period simulations. The 21st century simulations will be carried out using the Representative Concentration Pathway (RCP) storylines. This study will help quantify the importance of various environmental factors towards modeling land-atmosphere carbon exchange and better understand model related differences in CO2 estimates.

  8. A terrestrial vegetation turnover in the middle of the Early Triassic

    NASA Astrophysics Data System (ADS)

    Saito, Ryosuke; Kaiho, Kunio; Oba, Masahiro; Takahashi, Satoshi; Chen, Zhong-Qiang; Tong, Jinnan

    2013-06-01

    Land-plant productivity was greatly reduced after the end-Permian mass extinction, causing a pronounced "coal gap" worldwide during the Early Triassic. Newly obtained organic geochemistry data from the Chaohu area, south China, indicated an abrupt and profound terrestrial vegetation change over the middle part of the Early Triassic Smithian-Spathian (S-S) interval. Herbaceous lycopsids and/or bryophytes dominated terrestrial vegetation from Griesbachian to Smithian times. The terrestrial ecosystem underwent an abrupt change, and woody conifers became dominant over the S-S interval. Several important biomarkers, namely retene, simonellite, and dehydroabietane (with multiple sources: conifer, lycopsid, and/or herbaceous bryophyte), were relatively abundant during Griesbachian, Dienerian, and Smithian times. The relatively low C/N ratio values during the Griesbachian-Smithian interval indicate that these biomarkers were likely sourced from herbaceous lycopsids and/or bryophytes. The extremely abundant conifer-sourced pimanthrene, combined with relatively high C/N ratio values, suggested the recovery of woody conifers after the S-S boundary. The new data revealed that the switch from herbaceous vegetation to woody coniferous vegetation marked a terrestrial plant recovery, which occurred globally within 3 million years after the end-Permian crisis rather than at a later date estimated in previous studies. In Chaohu, the S-S terrestrial event was marked by a reappearance of woody vegetation, while the S-S marine event was marked by an increase in ichnodiversity, trace complexity, burrow size, infaunal tiering level, and bioturbation level, and a possible intense upwelling event indicated by the extended tricyclic terpane ratios (ETR). Coeval vegetation changes with comparable patterns have also been documented in Europe and Pakistan based on palynologic studies. The S-S boundaries in Asia and Europe are associated with a positive ?13C excursion, the rebound of woody vegetation, a turnover of ammonoid faunas, and possible global climate cooling. This is the first study to document the S-S event using biomarkers and C/N ratios.

  9. A terrestrial biosphere model optimized to atmospheric CO2 concentration and above ground woody biomass

    NASA Astrophysics Data System (ADS)

    Saito, M.; Ito, A.; Maksyutov, S. S.

    2013-12-01

    This study documents an optimization of a prognostic biosphere model (VISIT; Vegetation Integrative Similator for Trace gases) to observations of atmospheric CO2 concentration and above ground woody biomass by using a Bayesian inversion method combined with an atmospheric tracer transport model (NIES-TM; National Institute for Environmental Studies / Frontier Research Center for Global Change (NIES/FRCGC) off-line global atmospheric tracer transport model). The assimilated observations include 74 station records of surface atmospheric CO2 concentration and aggregated grid data sets of above ground woody biomass (AGB) and net primary productivity (NPP) over the globe. Both the biosphere model and the atmospheric transport model are used at a horizontal resolution of 2.5 deg x 2.5 deg grid with temporal resolutions of a day and an hour, respectively. The atmospheric transport model simulates atmospheric CO2 concentration with nine vertical levels using daily net ecosystem CO2 exchange rate (NEE) from the biosphere model, oceanic CO2 flux, and fossil fuel emission inventory. The models are driven by meteorological data from JRA-25 (Japanese 25-year ReAnalysis) and JCDAS (JMA Climate Data Assimilation System). Statistically optimum physiological parameters in the biosphere model are found by iterative minimization of the corresponding Bayesian cost function. We select thirteen physiological parameter with high sensitivity to NEE, NPP, and AGB for the minimization. Given the optimized physiological parameters, the model shows error reductions in seasonal variation of the CO2 concentrations especially in the northern hemisphere due to abundant observation stations, while errors remain at a few stations that are located in coastal coastal area and stations in the southern hemisphere. The model also produces moderate estimates of the mean magnitudes and probability distributions in AGB and NPP for each biome. However, the model fails in the simulation of the terrestrial vegetation compositions in some grids. These misfits are assumed to derive from simplified representation in the biosphere model without the impact of land use change and dire disturbance and the seasonal variability in the physiological parameters.

  10. The composition, spatial patterns, and influencing factors of atmospheric wet nitrogen deposition in Chinese terrestrial ecosystems.

    PubMed

    Zhu, Jianxing; He, Nianpeng; Wang, Qiufeng; Yuan, Guofu; Wen, Ding; Yu, Guirui; Jia, Yanlong

    2015-04-01

    Atmospheric nitrogen (N) deposition is an important component of the global N cycle, and is a key source of biologically available N. Understanding the spatio-temporal patterns and influencing factors of N deposition is essential to evaluate its ecological effects on terrestrial ecosystems, and to provide a scientific basis for global change research. In this study, we monitored the monthly atmospheric N deposition in rainfall at 41 stations from the Chinese Ecosystem Research Network through measuring total N (TN), total dissolved N (TDN), ammonium (NH4+-N), and nitrate (NO3--N). The results showed that the atmospheric wet deposition of TDN, NH4+-N, and NO3--N were 13.69, 7.25, and 5.93 kg N ha(-1) yr(-1), respectively. The deposition of TN and total particulate N (TPN) was 18.02 and 4.33 kg N ha(-1) yr(-1) respectively, in 2013. TPN accounted for 24% of TN, while NH4+-N and NO3--N made up 40% and 33%, respectively, confirming the assumption that atmospheric wet N deposition would be underestimated without particulate N in rainfall. The N deposition was higher in Central and Southern China, and lower in North-west, North-east, Inner Mongolia, and Qinghai-Tibet regions. Precipitation, N fertilizer use, and energy consumption were significantly correlated with wet N deposition (all p<0.01). Models that included precipitation and N fertilizer can explain 80-91% of the variability in wet N deposition. Our findings reveal, for the first time, the composition of the wet N deposition in China at different scales and highlight the importance of TPN. PMID:25617702

  11. Middle atmosphere electrodynamics: Report of the workshop on the Role of the Electrodynamics of the Middle Atmosphere on Solar Terrestrial Coupling

    NASA Technical Reports Server (NTRS)

    Maynard, N. C. (editor)

    1979-01-01

    Significant deficiencies exist in the present understanding of the basic physical processes taking place within the middle atmosphere (the region between the tropopause and the mesopause), and in the knowledge of the variability of many of the primary parameters that regulate Middle Atmosphere Electrodynamics (MAE). Knowledge of the electrical properties, i.e., electric fields, plasma characteristics, conductivity and currents, and the physical processes that govern them is of fundamental importance to the physics of the region. Middle atmosphere electrodynamics may play a critical role in the electrodynamical aspects of solar-terrestrial relations. As a first step, the Workshop on the Role of the Electrodynamics of the Middle Atmosphere on Solar-Terrestrial Coupling was held to review the present status and define recommendations for future MAE research.

  12. Terrestrial biospheric response to atmospheric CO[sub 2] and the [open quotes]missing carbon[close quotes

    Microsoft Academic Search

    A. W. King; W. R. Emanuel; S. D. Wullschleger; W. M. Post

    1993-01-01

    Part of the CO[sub 2] released to the atmosphere by the global use of fossil fuels remains unaccounted for in observations of atmospheric CO[sub 2] or model estimates of carbon uptake by the world's oceans. CO[sub 2] stimulation of terrestrial net primary production (NPP) has been proposed as a mechanism to account for this [open quotes]missing carbon[close quotes]. To assess

  13. Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 10611074 Seasonal variation of mesopause region wind shears,

    E-print Network

    2006-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 1061­1074 Seasonal variation of mesopause region wind shears, convective and dynamic instabilities above Fort Collins, CO: A statistical) temperature and horizontal wind, observed by Colorado State University sodium lidar over Fort Collins, CO (411

  14. Simulations of terrestrial carbon metabolism and atmospheric CO2 in a general circulation model. Part 1: Surface carbon fluxes

    Microsoft Academic Search

    A. Scott Denning; G. James Collatz; Changan Zhang; David A. Randall; Joseph A. Berry; Piers J. Sellers; Greg D. Colell; Donald A. Dazlich

    1996-01-01

    The exchange of carbon dioxide (CO2) between the atmosphere and terrestrial ecosystems due to photosynthesis and respiration has been simulated using a new version of the simple biosphere model (SiB2) and the Colorado State University (CSU) general circulation model (GCM). Parameters associated with the extent and seasonality of vegetation were derived from satellite observations. The fluxes were calculated at the

  15. Three-dimensional tracer model study of atmospheric CO2 - Response to seasonal exchanges with the terrestrial biosphere

    Microsoft Academic Search

    I. Fung; K. Prentice; E. Matthews; J. Lerner; G. Russell

    1983-01-01

    A three-dimensional tracer transport model is used to investigate the annual cycle of atmospheric CO2 concentration produced by seasonal exchanges with the terrestrial biosphere. The tracer model uses winds generated by a global general circulation model to advect and convect CO2; no explicit diffusion coefficients are employed. A biospheric exchange function constructed from a map of net primary productivity, and

  16. Journal of Atmospheric and Solar-Terrestrial Physics 69 (2007) 24652484 Acousticgravity waves during solar eclipses: Detection and

    E-print Network

    Roux, Stephane

    2007-01-01

    ) in the observatory Pru° honice (49.9N, 14.5E, Czech Republic). The aim of these experiments is to analyze the changesJournal of Atmospheric and Solar-Terrestrial Physics 69 (2007) 2465­2484 Acoustic­gravity waves of the generated acoustic­gravity waves (AGWs). Second, injecting wave vector components measured from the data

  17. Early tetrapod evolution and the progressive integration of Permo-Carboniferous terrestrial ecosystems

    SciTech Connect

    Beerbower, J.R. (State Univ., Binghamton, NY (United States). Dept. of Geological Science); Olson, E.C. (Univ. of California, Los Angeles, CA (United States). Dept. of Biology); Hotton, N. III (Smithsonian, Washington, DC (United States). Dept. of Paleobiology)

    1992-01-01

    Variation among Permo-Carboniferous tetrapod assemblages demonstrates major transformations in pathways and rates of energy and nutrient transfer, in integration of terrestrial ecosystems and in predominant ecologic modes. Early Carboniferous pathways were through plant detritus to aquatic and terrestrial detritivores and thence to arthropod and vertebrate meso-and macro-predators. Transfer rates (and efficiency) were low as was ecosystem integration; the principal ecologic mode was conservation. Late Carboniferous and Early Permian assemblages demonstrate an expansion in herbivory, primarily in utilization of low-fiber plant tissue by insects. But transfer rates, efficiency and integration were still limited because the larger portion of plant biomass, high-fiber tissues, still went into detrital pathways; high-fiber'' herbivores, i.e., tetrapods, were neither abundant or diverse, reflecting limited resources, intense predation and limited capabilities for processing fiber-rich food. The abundance and diversity of tetrapod herbivores in upper Permian assemblages suggests a considerable transfer of energy from high-fiber tissues through these animals to tetrapod predators and thus higher transfer rates and efficiencies. It also brought a shift in ecological mode toward acquisition and regulation and tightened ecosystem integration.

  18. Simple global carbon model: The atmosphere-terrestrial biosphere-ocean interaction

    SciTech Connect

    Kwon, O.Y.; Schnoor, J.L. [Univ. of Iowa, Iowa City, IA (United States)] [Univ. of Iowa, Iowa City, IA (United States)

    1994-09-01

    A simple global carbon model has been developed for scenario analysis, and research needs prioritization. CO{sub 2} fertilization and temperature effects are included in the terrestrial biosphere compartment, and the ocean compartment includes inorganic chemistry which, with ocean water circulation, enables the calculation of time-variable oceanic carbon uptake. Model-derived Q{sub 10} values (the increasing rate for every 10{degrees}C increase of temperature) are 1.37 for land biota photosynthesis, 1.89 for land biota respiration, and 1.95 for soil respiration, and feedback temperature is set at 0.01{degrees}C/ppm of CO{sub 2}. These could be the important parameters controlling the carbon cycle in potential global warming scenarios. Scenario analysis, together with sensitivity analysis of temperature feedback, suggests that if CO{sub 2} emissions from fossil fuel combustion continue at the present increasing rate of {approximately}1.5% per year, a CO{sub 2} doubling (to 560 ppm) will appear in year 2060. Global warming would be responsible for 40 Gt as carbon (Gt C) accumulation in the land biota, 88 Gt C depletion from the soil carbon, a 7 Gt C accumulation in the oceans, and a 19 ppm increase in atmospheric CO{sub 2}. The ocean buffering capacity to take up the excess CO{sub 2} will decrease with the increasing atmospheric CO{sub 2} concentration. 51 refs., 8 figs., 3 tabs.

  19. Estimating Terrestrial Wood Biomass from Observed Concentrations of Atmospheric Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Schaefer, K. M.; Peters, W.; Carvalhais, N.; van der Werf, G.; Miller, J.

    2008-12-01

    We estimate terrestrial disequilibrium state and wood biomass from observed concentrations of atmospheric CO2 using the CarbonTracker system coupled to the SiBCASA biophysical model. Starting with a priori estimates of carbon flux from the land, ocean, and fossil fuels, CarbonTracker estimates net carbon sources and sinks from 2000 to 2007 that are optimally consistent with observed CO2 concentrations. The a priori terrestrial Net Primary Productivity (NPP) and heterotrophic respiration (Rh) from SiBCASA assume steady state conditions for initial biomass, implying mature ecosystems with no disturbances where growth balances decay and the long-term, net carbon flux is zero. In reality, harvest, fires, and other disturbances reduce available biomass for decay, thus reducing Rh and resulting in a long-term carbon sink. The disequilibrium state is the ratio of Rh estimated from CarbonTracker to the steady state Rh from SiBCASA. Wood is the largest carbon pool in forest ecosystems and the dominant source of dead organic matter to the soil and litter pools. With much faster turnover times, the soil and litter pools reach equilibrium relative to the wood pool long before the wood pool itself reaches equilibrium. We take advantage of this quasi-steady state to estimate the size of the wood pool that will produce an Rh that corresponds to the net carbon sink from CarbonTracker. We then compare this estimated wood biomass to regional maps of observed above ground wood biomass from the US Forest Inventory Analysis.

  20. Using Dimers to Measure Biosignatures and Atmospheric Pressure for Terrestrial Exoplanets

    PubMed Central

    Meadows, Victoria; Claire, Mark; Crisp, Dave

    2014-01-01

    Abstract We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 ?m dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bar and for O2 volume mixing ratios above 50% of Earth's present-day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 ?m and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We also performed detectability studies for JWST transit transmission spectroscopy and found that the 1.06 and 1.27??m dimer features could be detectable (SNR>3) for an Earth analogue orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis. We calculated the required signal-to-noise ratios to detect and characterize O2 monomer and dimer features in direct imaging–reflected spectra and found that signal-to-noise ratios greater than 10 at a spectral resolving power of R=100 would be required. Key Words: Remote sensing—Extrasolar terrestrial planets—Habitability—Radiative transfer—Biosignatures. Astrobiology 14, 67–86. PMID:24432758

  1. The rise of oxygen in Earth's early ocean and atmosphere.

    PubMed

    Lyons, Timothy W; Reinhard, Christopher T; Planavsky, Noah J

    2014-02-20

    The rapid increase of carbon dioxide concentration in Earth's modern atmosphere is a matter of major concern. But for the atmosphere of roughly two-and-half billion years ago, interest centres on a different gas: free oxygen (O2) spawned by early biological production. The initial increase of O2 in the atmosphere, its delayed build-up in the ocean, its increase to near-modern levels in the sea and air two billion years later, and its cause-and-effect relationship with life are among the most compelling stories in Earth's history. PMID:24553238

  2. The sensitivity of terrestrial carbon storage to historical climate variability and atmospheric CO2 in the United States

    USGS Publications Warehouse

    Tian, H.; Melillo, J.M.; Kicklighter, D.W.; McGuire, A.D.; Helfrich, J.

    1999-01-01

    We use the Terrestrial Ecosystem Model (TEM, Version 4.1) and the land cover data set of the international geosphere-biosphere program to investigate how increasing atmospheric CO2 concentration and climate variability during 1900-1994 affect the carbon storage of terrestrial ecosystems in the conterminous USA, and how carbon storage has been affected by land-use change. The estimates of TEM indicate that over the past 95 years a combination of increasing atmospheric CO2 with historical temperature and precipitation variability causes a 4.2% (4.3 Pg C) decrease in total carbon storage of potential vegetation in the conterminous US, with vegetation carbon decreasing by 7.2% (3.2 Pg C) and soil organic carbon decreasing by 1.9% (1.1 Pg C). Several dry periods including the 1930s and 1950s are responsible for the loss of carbon storage. Our factorial experiments indicate that precipitation variability alone decreases total carbon storage by 9.5%. Temperature variability alone does not significantly affect carbon storage. The effect of CO2 fertilization alone increases total carbon storage by 4.4%. The effects of increasing atmospheric CO2 and climate variability are not additive. Interactions among CO2, temperature and precipitation increase total carbon storage by 1.1%. Our study also shows substantial year-to-year variations in net carbon exchange between the atmosphere and terrestrial ecosystems due to climate variability. Since the 1960s, we estimate these terrestrial ecosystems have acted primarily as a sink of atmospheric CO2 as a result of wetter weather and higher atmospheric CO2 concentrations. For the 1980s, we estimate the natural terrestrial ecosystems, excluding cropland and urban areas, of the conterminous US have accumulated 78.2 Tg C yr-1 because of the combined effect of increasing atmospheric CO2 and climate variability. For the conterminous US, we estimate that the conversion of natural ecosystems to cropland and urban areas has caused a 18.2% (17.7 Pg C) reduction in total carbon storage from that estimated for potential vegetation. The carbon sink capacity of natural terrestrial ecosystems in the conterminous US is about 69% of that estimated for potential vegetation.

  3. Journal of the Atmospheric Sciences EARLY ONLINE RELEASE

    E-print Network

    Pauluis, Olivier M.

    Journal of the Atmospheric Sciences EARLY ONLINE RELEASE This is a preliminary PDF of the author: Examination of Isentropic Circulation Response to A Doubling of Carbon Dioxide Using Statistical Transformed Examination of Isentropic Circulation1 Response to A Doubling of Carbon Dioxide2 Using Statistical Transformed

  4. Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review.

    PubMed

    Krupa, S V

    2003-01-01

    At the global scale, among all N (nitrogen) species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH3 (ammonia) is considered to be the foremost. The major sources for atmospheric NH3 are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to its sources, acute exposures to NH3 can result in visible foliar injury on vegetation. NH3 is deposited rapidly within the first 4-5 km from its source. However, NH3 is also converted in the atmosphere to fine particle NH4+ (ammonium) aerosols that are a regional scale problem. Much of our current knowledge of the effects of NH3 on higher plants is predominantly derived from studies conducted in Europe. Adverse effects on vegetation occur when the rate of foliar uptake of NH3 is greater than the rate and capacity for in vivo detoxification by the plants. Most to least sensitive plant species to NH3 are native vegetation > forests > agricultural crops. There are also a number of studies on N deposition and lichens, mosses and green algae. Direct cause and effect relationships in most of those cases (exceptions being those locations very close to point sources) are confounded by other environmental factors, particularly changes in the ambient SO2 (sulfur dioxide) concentrations. In addition to direct foliar injury, adverse effects of NH3 on higher plants include alterations in: growth and productivity, tissue content of nutrients and toxic elements, drought and frost tolerance, responses to insect pests and disease causing microorganisms (pathogens), development of beneficial root symbiotic or mycorrhizal associations and inter species competition or biodiversity. In all these cases, the joint effects of NH3 with other air pollutants such as all-pervasive O3 or increasing CO2 concentrations are poorly understood. While NH3 uptake in higher plants occurs through the shoots, NH4+ uptake occurs through the shoots, roots and through both pathways. However, NH4+ is immobile in the soil and is converted to NO3- (nitrate). In agricultural systems, additions of NO3- to the soil (initially as NH3 or NH4+) and the consequent increases in the emissions of N2O (nitrous oxide, a greenhouse gas) and leaching of NO3- into the ground and surface waters are of major environmental concern. At the ecosystem level NH3 deposition cannot be viewed alone, but in the context of total N deposition. There are a number of forest ecosystems in North America that have been subjected to N saturation and the consequent negative effects. There are also heathlands and other plant communities in Europe that have been subjected to N-induced alterations. Regulatory mitigative approaches to these problems include the use of N saturation data or the concept of critical loads. Current information suggests that a critical load of 5-10 kg ha(-1) year(-1) of total N deposition (both dry and wet deposition combined of all atmospheric N species) would protect the most vulnerable terrestrial ecosystems (heaths, bogs, cryptogams) and values of 10-20 kg ha(-1) year(-1) would protect forests, depending on soil conditions. However, to derive the best analysis, the critical load concept should be coupled to the results and consequences of N saturation. PMID:12713921

  5. Mobile sampler for use in acquiring samples of terrestrial atmospheric gases

    NASA Technical Reports Server (NTRS)

    Tucker, C. E.; Holway, H. P. (inventors)

    1981-01-01

    Samples of terrestrial atmospheric gasses from a free body of such gasses using a device characterized by a plurality of tubular bodies adapted to be mounted in side by side relation on a motorized highway vehicle in mutual parallelism with the axis of the normal path of travel for the vehicles. Each of the bodies is of a cylindrical configuration and has an axial opening at each of its opposite ends through which a linear flow path is defined. A pair of pivotally supported, spring-biased sealing caps is mounted adjacent to the ends of the body and continuously urged into a hermetic sealing relationship. A restraint for securing the caps against spring-urged pivotal displacement, includes a separable, normally tensioned line interconnecting the caps and an operable release mechanism for simultaneously releasing the caps for spring-urged displacement. A hot wire cutter is included for separating the line, whereby samples of air are trapped in the body as the caps are spring-driven to assume an hermetically sealed relation with the openings defined in each of the opposite ends of the body.

  6. Requirements for the early atmosphere of Mars from nitrogen isotope ratios

    NASA Technical Reports Server (NTRS)

    Fox, J. L.

    1993-01-01

    The N escape models of Fox and Dalgarno and Fox required the presence of a dense, early CO2 atmosphere to inhibit fractionation of the N isotopes N-15 and N-14. The computed photochemical escape fluxes are so large at the present that the isotope ratio measured by Viking (about 1.62x terrestrial) can be produced in about 1.5 b.y. This model was refined in several ways. It was updated to incorporate the variation of the escape fluxes with increases in the solar fluxes at earlier times according to the model of Zahnle and Walker. As expected, this exacerbates the problem with overfractionation, but not greatly. Most of the escape and fractionation of the N occurs in the last 1.5 b.y., when the solar flux was only slightly different from the present. The dense early atmosphere must persist only a bit longer in order to reproduce the measured isotope ratio. The model was also modified to take into account changes in the O mixing ratio with time in the past, assuming that the O abundance is proportional to the square root of the solar flux. Although the production rate of O from photodissociation of CO2 scales as the solar flux, the strength of the winds and other mixing processes also increases with the solar flux, resulting in possibly more effective transport of O to the lower atmosphere where it is destroyed by catalytic and three-body recombination mechanisms.

  7. Increased delivery of condensation nuclei during the Late Heavy Bombardment to the terrestrial and martian atmospheres

    NASA Astrophysics Data System (ADS)

    Losiak, Anna

    2014-05-01

    During the period of the Late Heavy Bombardment (LHB), between 4.1 and 3.8 Ga, the impact rate within the entire Solar System was up to a few thousand times higher than the current value (Ryder 2002, Bottke et al. 2012, Fassett and Minton 2013). Multiple basin-forming events on inner planets that occurred during this time had a strong but short-lasting (up to few thousands of years) effect on atmospheres of Earth and Mars (Sleep et al. 1989, Segura et al. 2002, 2012). However, the role of the continuous flux of smaller impactors has not been assessed so far. We calculated the amount of meteoric material in the 10^-3 kg to 106 kg size range delivered to Earth and Mars during the LHB based on the impact flux at the top of the Earth's atmosphere based on results from Bland and Artemieva (2006). Those values were recalculated for Mars based on Ivanov and Hartmann (2009) and then recalculated to the LHB peak based on estimates from Ryder (2002), Bottke et al. (2012), Fassett and Minton (2013). During the LHB, the amount of meteoritic material within this size range delivered to Earth was up to ~1.7*10^10 kg/year and 1.4*10^10 kg/year for Mars. The impactors that ablate and are disrupted during atmospheric entry can serve as cloud condensation nuclei (Rosen 1968, Hunten et al. 1980, Ogurtsov and Raspopov 2011). The amount of material delivered during LHB to the upper stratosphere and lower mezosphere (Hunten et al. 1980, Bland and Artemieva 2006) is comparable to the current terrestrial annual emission of mineral cloud condensation nuclei of 0.5-8*10^12 kg/year (Tegen 2003). On Mars, the availability of condensation nuclei is one of the main factors guiding water-ice cloud formation (Montmessin et al. 2004), which is in turn one of the main climatic factors influencing the hydrological cycle (Michaels et al. 2006) and radiative balance of the planet (Haberle et al. 1999, Wordsworth et al. 2013, Urata and Toon 2013). Increased delivery of condensation nuclei during the LHB should be taken into account when constructing models of terrestrial and Martian climates around 4 Ga. Bland P.A., Artemieva N.A. (2006) Meteorit.Planet.Sci. 41:607-631. Bottke W.F. et al. (2012) Nature 485: 78-81. Fassett C.I., Minton D.A. (2013) Nat.Geosci. 6:520-524 (2013). Hunten D.M. et al. (1980) J.Atmos.Sci. 37:1342-1357. Haberle R.M. et al. (1999) J.Geophys.Res. 104:8957-8974. Ivanov B.A., Hartmann W.K. (2009) Planets and Moons: Treatise on Geophysics (eds. Spohn T.): 207-243. Michaels T.I. et al. (2006) Geophys.Res.Lett. 33:L16201. Montmessin F. et al. (2004) J.Geophys.Res. 109:E10004. Ogurtsov M.G., Raspopov O.M. (2011) Geomagnetism&Aeronomy 51:275-283. Rosen J.M. (1968) Space Sci.Rev. 9:58-89. Ryder G. (2002) J.Geophys.Res. 107: doi:10.1029/2001JE001583. Segura T.L. et al. (2002) Science 298:1977-1980. Segura T.L. et al. (2012) Icarus 220:144-148. Sleep N.S. et al. (1989) Nature 342:139-142. Tegen I. (2003) Quat.Sci.Rev. 22:1821-1834. Urata R.A., Toon O.B. (2013) Icarus 226:229-250. Wordsworth R. et al. (2012) Icarus 222:1-19.

  8. A carbon dioxide/methane greenhouse atmosphere on early Mars

    NASA Technical Reports Server (NTRS)

    Brown, L. L.; Kasting, J. F.

    1993-01-01

    One explanation for the formation of fluvial surface features on early Mars is that the global average surface temperature was maintained at or above the freezing point of water by the greenhouse warming of a dense CO2 atmosphere; however, Kasting has shown that CO2 alone is insufficient because the formation of CO2 clouds reduces the magnitude of the greenhouse effect. It is possible that other gases, such as NH3 and CH4, were present in the early atmosphere of Mars and contributed to the greenhouse effect. Kasting et al. investigated the effect of NH3 in a CO2 atmosphere and calculated that an NH3 mixing ratio of approximately 5 x 10 (exp -4) by volume, combined with a CO2 partial pressure of 4-5 bar, could generate a global average surface temperature of 273 K near 3.8 b.y. ago when the fluvial features are believed to have formed. Atmospheric NH3 is photochemically converted to N2 by ultraviolet radiation at wavelengths shortward of 230 nm; maintenance of sufficient NH3 concentrations would therefore require a source of NH3 to balance the photolytic destruction. We have used a one-dimensional photochemical model to estimate the magnitude of the NH3 source required to maintain a given NH3 concentration in a dense CO2 atmosphere. We calculate that an NH3 mixing ratio of 10(exp -4) requires a flux of NH3 on the order of 10(exp 12) molecules /cm-s. This figure is several orders of magnitude greater than estimates of the NH3 flux on early Mars; thus it appears that NH3 with CO2 is not enough to keep early Mars warm.

  9. Terrestrial origin of viviparity in mesozoic marine reptiles indicated by early triassic embryonic fossils.

    PubMed

    Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

    2014-01-01

    Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction. PMID:24533127

  10. Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils

    PubMed Central

    Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

    2014-01-01

    Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction. PMID:24533127

  11. An approach to balancing the positive and negative effects of elevated nitrogen oxides in the lower atmosphere on terrestrial plants.

    PubMed

    Semenov, S

    2001-09-24

    Elevated NOx in the lower atmosphere has three major effects on terrestrial plants. On the one hand, it causes an increase in surface ozone concentration. This reduces plant growth rate. On the other hand, elevated NOx causes an increase in the flux of oxidized N compounds from the atmosphere to the land surface. This plays a dual role in the life of terrestrial plants. Additional N in soils stimulates plant growth (N-fertilization effect), whereas soil acidification may negatively affect plants. A simple empirical model for calculating the overall effect of anthropogenic increase in NOx level has been developed. The model is based on experimental "cause-response" data presented in world scientific literature. Calculations showed that at the large scale, among the above-mentioned changes, elevated O3 plays a major and negative role in plant life. Its negative effect on plants is partly compensated by N fertilization in unmanaged ecosystems. Such compensation appears to be negligible in agricultural lands. There are vast territories in Euro--Asia--for instance, a territory of Russia--in which acid atmospheric deposition has no significant effect on terrestrial plants. PMID:12806067

  12. Terrestrial biospheric response to atmospheric CO[sub 2] and the [open quotes]missing carbon[close quotes

    SciTech Connect

    King, A.W.; Emanuel, W.R.; Wullschleger, S.D.; Post, W.M. (Oak Ridge National Lab., TN (United States))

    1993-06-01

    Part of the CO[sub 2] released to the atmosphere by the global use of fossil fuels remains unaccounted for in observations of atmospheric CO[sub 2] or model estimates of carbon uptake by the world's oceans. CO[sub 2] stimulation of terrestrial net primary production (NPP) has been proposed as a mechanism to account for this [open quotes]missing carbon[close quotes]. To assess this proposition, we use a global model of carbon dynamics in terrestrial ecosystems. Plant growth is a logistic function of vegetation carbon density. We model the CO[sub 2] response of NPP as a logarithmic function of increasing atmospheric CO[sub 2] (the classic response function of global carbon cycle models) and as a more physiologically justified rectangular hyperbolic response. We derive parameters for these functions from experimental studies of plant response to suggest a recent upper limit on CO[sub 2] stimulated terrestrial carbon storage of [approx]0.5 Gt C yr[sup [minus]1] and a maximum CO[sub 2] enhance storage is sufficient to account for the [open quotes]missing[close quotes] fossil fuel carbon releases, but it is sufficient to also account for most estimates of the additional carbon released by changes in land use.

  13. Atmospheric composition and climate on the early Earth

    PubMed Central

    Kasting, James F; Howard, M. Tazewell

    2006-01-01

    Oxygen isotope data from ancient sedimentary rocks appear to suggest that the early Earth was significantly warmer than today, with estimates of surface temperatures between 45 and 85°C. We argue, following others, that this interpretation is incorrect—the same data can be explained via a change in isotopic composition of seawater with time. These changes in the isotopic composition could result from an increase in mean depth of the mid-ocean ridges caused by a decrease in geothermal heat flow with time. All this implies that the early Earth was warm, not hot. A more temperate early Earth is also easier to reconcile with the long-term glacial record. However, what triggered these early glaciations is still under debate. The Paleoproterozoic glaciations at approximately 2.4?Ga were probably caused by the rise of atmospheric O2 and a concomitant decrease in greenhouse warming by CH4. Glaciation might have occurred in the Mid-Archaean as well, at approximately 2.9?Ga, perhaps as a consequence of anti-greenhouse cooling by hydrocarbon haze. Both glaciations are linked to decreases in the magnitude of mass-independent sulphur isotope fractionation in ancient rocks. Studying both the oxygen and sulphur isotopic records has thus proved useful in probing the composition of the early atmosphere. PMID:17008214

  14. Atmospheric composition and climate on the early Earth.

    PubMed

    Kasting, James F; Howard, M Tazewell

    2006-10-29

    Oxygen isotope data from ancient sedimentary rocks appear to suggest that the early Earth was significantly warmer than today, with estimates of surface temperatures between 45 and 85 degrees C. We argue, following others, that this interpretation is incorrect-the same data can be explained via a change in isotopic composition of seawater with time. These changes in the isotopic composition could result from an increase in mean depth of the mid-ocean ridges caused by a decrease in geothermal heat flow with time. All this implies that the early Earth was warm, not hot.A more temperate early Earth is also easier to reconcile with the long-term glacial record. However, what triggered these early glaciations is still under debate. The Paleoproterozoic glaciations at approximately 2.4Ga were probably caused by the rise of atmospheric O2 and a concomitant decrease in greenhouse warming by CH4. Glaciation might have occurred in the Mid-Archaean as well, at approximately 2.9Ga, perhaps as a consequence of anti-greenhouse cooling by hydrocarbon haze. Both glaciations are linked to decreases in the magnitude of mass-independent sulphur isotope fractionation in ancient rocks. Studying both the oxygen and sulphur isotopic records has thus proved useful in probing the composition of the early atmosphere. PMID:17008214

  15. Land Use Effects on Atmospheric C-13 Imply a Sizable Terrestrial CO2 Sink in Tropical Latitudes

    NASA Technical Reports Server (NTRS)

    Townsend, Alan R.; Asner, Gregory P.; Tans, Pieter P.; White, James W. C.

    2000-01-01

    Records of atmospheric CO2 and 13-CO2, can be used to distinguish terrestrial vs. oceanic exchanges of CO2 with the atmosphere. However, this approach has proven difficult in the tropics, partly due to extensive land conversion from C-3 to C-4 vegetation. We estimated the effects of such conversion on biosphere-atmosphere C-13 exchange for 1991 through 1999, and then explored how this 'land-use disequilibrium' altered the partitioning of net atmospheric CO2 exchanges between ocean and land using NOAA-CMDL data and a 2D, zonally averaged atmospheric transport model. Our results show sizable CO2 uptake in C-3-dominated tropical regions in seven of the nine years; 1997 and 1998, which included a strong ENSO event, are near neutral. Since these fluxes include any deforestation source, our findings imply either that such sources are smaller than previously estimated, and/or the existence of a large terrestrial CO2 sink in equatorial latitudes.

  16. Hydrogen-nitrogen greenhouse warming in Earth's early atmosphere.

    PubMed

    Wordsworth, Robin; Pierrehumbert, Raymond

    2013-01-01

    Understanding how Earth has sustained surface liquid water throughout its history remains a key challenge, given that the Sun's luminosity was much lower in the past. Here we show that with an atmospheric composition consistent with the most recent constraints, the early Earth would have been significantly warmed by H(2)-N(2) collision-induced absorption. With two to three times the present-day atmospheric mass of N(2) and a H(2) mixing ratio of 0.1, H(2)-N(2) warming would be sufficient to raise global mean surface temperatures above 0°C under 75% of present-day solar flux, with CO(2) levels only 2 to 25 times the present-day values. Depending on their time of emergence and diversification, early methanogens may have caused global cooling via the conversion of H(2) and CO(2) to CH(4), with potentially observable consequences in the geological record. PMID:23288536

  17. Quantitative Hydraulic Models Of Early Land Plants Provide Insight Into Middle Paleozoic Terrestrial Paleoenvironmental Conditions

    NASA Astrophysics Data System (ADS)

    Wilson, J. P.; Fischer, W. W.

    2010-12-01

    Fossil plants provide useful proxies of Earth’s climate because plants are closely connected, through physiology and morphology, to the environments in which they lived. Recent advances in quantitative hydraulic models of plant water transport provide new insight into the history of climate by allowing fossils to speak directly to environmental conditions based on preserved internal anatomy. We report results of a quantitative hydraulic model applied to one of the earliest terrestrial plants preserved in three dimensions, the ~396 million-year-old vascular plant Asteroxylon mackei. This model combines equations describing the rate of fluid flow through plant tissues with detailed observations of plant anatomy; this allows quantitative estimates of two critical aspects of plant function. First and foremost, results from these models quantify the supply of water to evaporative surfaces; second, results describe the ability of plant vascular systems to resist tensile damage from extreme environmental events, such as drought or frost. This approach permits quantitative comparisons of functional aspects of Asteroxylon with other extinct and extant plants, informs the quality of plant-based environmental proxies, and provides concrete data that can be input into climate models. Results indicate that despite their small size, water transport cells in Asteroxylon could supply a large volume of water to the plant's leaves--even greater than cells from some later-evolved seed plants. The smallest Asteroxylon tracheids have conductivities exceeding 0.015 m^2 / MPa * s, whereas Paleozoic conifer tracheids do not reach this threshold until they are three times wider. However, this increase in conductivity came at the cost of little to no adaptations for transport safety, placing the plant’s vegetative organs in jeopardy during drought events. Analysis of the thickness-to-span ratio of Asteroxylon’s tracheids suggests that environmental conditions of reduced relative humidity (<20%) combined with elevated temperatures (>25°C) could cause sufficient cavitation to reduce hydraulic conductivity by 50%. This suggests that the Early Devonian environments that supported the earliest vascular plants were not subject to prolonged midseason droughts, or, alternatively, that the growing season was short. This places minimum constraints on water availability (e.g., groundwater hydration, relative humidity) in locations where Asteroxylon fossils are found; these environments must have had high relative humidities, comparable to tropical riparian environments. Given these constraints, biome-scale paleovegetation models that place early vascular plants distal to water sources can be revised to account for reduced drought tolerance. Paleoclimate proxies that treat early terrestrial plants as functionally interchangeable can incorporate physiological differences in a quantitatively meaningful way. Application of hydraulic models to fossil plants provides an additional perspective on the 475 million-year history of terrestrial photosynthetic environments and has potential to corroborate other plant-based paleoclimate proxies.

  18. Late Paleocene-early Eocene carbon isotope stratigraphy from a near-terrestrial tropical section and antiquity of Indian mammals

    NASA Astrophysics Data System (ADS)

    Samanta, A.; Sarkar, A.; Bera, M. K.; Rai, Jyotsana; Rathore, S. S.

    2013-02-01

    Late Paleocene to early Eocene (~56 to 51 Ma) interval is characterized by five distinct transient warming (hyperthermal) events (Paleocene-Eocene thermal maximum (PETM), H1/ETM2/ELMO, H2, I1 and I2) in a super greenhouse globe associated with negative carbon isotope excursions (CIEs). Although well-documented marine records exist at different latitudes, terrestrial PETM sections are rare. In particular, almost no terrestrial records of either the PETM or early Eocene hyperthermals (EEHs) are yet available from the tropics. Further, evolution of modern order of mammals near the PETM has been recorded in many northern continents; however, the response of mammals in the tropics to these warming events is unknown. A tropical terrestrial record of these hyperthermal/CIE events, encompassing the earliest modern order mammal bearing horizon from India, can therefore be vital in understanding climatic and biotic evolution during the earliest Cenozoic time. Here, for the first time, we report high resolution carbon isotope ( ? 13C) stratigraphy, nannofossil, and Sr isotope ratio of marine fossil carbonate from the Cambay Shale Formation of Western India. The record shows complete preservation of all the above CIE events, including the PETM, hitherto unknown from the equatorial terrestrial records. ? 13C chemostratigraphy further suggests that at least the present early Eocene mammal-bearing horizon, recently discovered at Vastan, does not support the `out of India' hypothesis of earliest appearance of modern mammals and subsequent dispersal to the Holarctic continents.

  19. The Role of Hydrogen in Determining the Stability of CO2 Atmospheres of Terrestrial Exoplanets Around M Dwarfs

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Hu, Renyu; Robinson, Tyler D.; Yung, Yuk L.

    2014-11-01

    The recent discovery of terrestrial worlds in the Habitable Zones of M Dwarfs necessitates a more intensive investigation of the properties of these planets. One major feature of certain M Dwarfs is their high fluxes of EUV radiation, which photolyzes CO2, an important greenhouse gas that should be abundant on rocky worlds. This photolytic destruction of CO2 can be countered by HOx chemistry: photolysis of HOx species by NUV radiation generates OH, which reacts with CO to regenerate CO2. These processes are balanced around Sun-like stars such that Venus and Mars can maintain CO2-dominated atmospheres. However, M Dwarfs tend to have much lower NUV/EUV flux ratios, which could prevent the formation of significant CO2 atmospheres on any planets they may host. In this study, we evaluate the properties of CO2 atmospheres surrounding an Earth-massed, Earth-sized exoplanet in orbit of an M Dwarf using a 1D photochemical kinetics model. We consider an atmosphere similar in composition to that of Mars, but scaled to have a surface pressure of 1 bar. We choose to focus on Mars-like atmospheres rather than Earth-like ones, as Earth's atmosphere has been altered through biological sources and sinks and the presence of a large liquid water ocean, which are not necessarily present on terrestrial exoplanets. Our preliminary results show that the hydrogen content of the atmosphere is crucial in determining the ratio of CO2 to CO and O2. In particular, for a H2 mixing ratio identical to that of Mars 20-30 ppm), a steady state atmosphere is reached after 10 Gyr consisting of ~85% CO2, ~10% CO, and ~5% O2, with an ozone mixing ratio of ~0.01 ppm. In the extreme case where all hydrogen is lost to space, an atmosphere consisting of ~64% CO2, ~24% CO, and 12% O2 results, while ozone levels reach ~10 ppm. Finally, for H2 mixing ratios similar to that of Earth 0.5 ppm) and no atmospheric escape, a 49% CO2, 34% CO, 17% O2, and 0.1 ppm O3 atmosphere is possible. This not only points to the potential prevalence of abiotic O2 and O3 in M Dwarf exoplanet atmospheres, but also that hydrogen species, including H2O, are essential in determining the global atmospheric makeup of these planets despite their relatively low concentrations.

  20. Satellite observations of terrestrial water storage provide early warning information about drought and fire season severity in the Amazon

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Velicogna, Isabella; Famiglietti, James S.; Randerson, James T.

    2013-06-01

    risk in the Amazon can be predicted several months before the onset of the dry season using sea surface temperatures in the tropical north Atlantic and tropical Pacific. The lead times between ocean state and the period of maximum burning (4-11 months) may enable the development of forecasts with benefits for forest conservation, yet the underlying physical and biological mechanisms responsible for these temporal offsets are not well known. Here, we examined the hypothesis that year-to-year variations in soil water recharge during the wet season modify atmospheric water vapor and fire behavior during the following dry season. We tested this hypothesis by analyzing terrestrial water storage observations from the Gravity Recovery and Climate Experiment (GRACE), active fires from the Moderate Resolution Imaging Spectroradiometer (MODIS), and several other satellite and atmospheric reanalysis datasets during 2002-2011. We found that terrestrial water storage deficits preceded severe fire seasons across the southern Amazon. The most significant relationships between monthly terrestrial water storage and the sum of active fires during the dry season occurred during April-August (p < 0.02), corresponding to 1-5 month lead times before the peak month of burning (September). Analysis of other datasets provided evidence for a cascade of processes during drought events, with lower cumulative precipitation (and higher cumulative evapotranspiration) in the wet season substantially reducing terrestrial water storage, and subsequently, surface and column atmospheric water vapor. Our results suggest that terrestrial water storage observations from GRACE have the potential to improve fire season forecasts for the southern Amazon.

  1. A Process-based Analysis of Methane Exchanges Between Alaskan Terrestrial Ecosystems and the Atmosphere

    E-print Network

    Zhuang, Qianlai.

    We developed and used a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in Alaskan soils have changed over the past century in response to observed changes ...

  2. The "terminal Triassic catastrophic extinction event" in perspective: a review of carboniferous through Early Jurassic terrestrial vertebrate extinction patterns

    USGS Publications Warehouse

    Weems, R.E.

    1992-01-01

    A catastrophic terminal Triassic extinction event among terrestrial vertebrates is not supported by available evidence. The current model for such an extinction is based on at least eight weak or untenable assumptions: (1) a terminal Triassic extinction-inducing asteroid impact occurred, (2) a terminal Triassic synchronous mass extinction of terrestrial vertebrates occurred, (3) a concurrent terminal Triassic marine extinction occurred, (4) all terrestrial vertebrate families have similar diversities and ecologies, (5) changes in familial diversity can be gauged accurately from the known fossil record, (6) extinction of families can be compared through time without normalizing for changes in familial diversity through time, (7) extinction rates can be compared without normalizing for differing lengths of geologic stages, and (8) catastrophic mass extinctions do not select for small size. These assumptions have resulted in unsupportable and (or) erroneous conclusions. Carboniferous through Early Jurassic terrestrial vertebrate families mostly have evolution and extinction patterns unlike the vertebrate evolution and extinction patterns during the terminal Cretaceous event. Only the Serpukhovian (mid Carboniferous) extinction event shows strong analogy to the terminal Cretaceous event. Available data suggest no terminal Triassic extinction anomaly, but rather a prolonged and nearly steady decline in the global terrestrial vertebrate extinction rate throughout the Triassic and earliest Jurassic. ?? 1992.

  3. PHOTOCHEMISTRY IN TERRESTRIAL EXOPLANET ATMOSPHERES. III. PHOTOCHEMISTRY AND THERMOCHEMISTRY IN THICK ATMOSPHERES ON SUPER EARTHS AND MINI NEPTUNES

    E-print Network

    Hu, Renyu

    Some super Earths and mini Neptunes will likely have thick atmospheres that are not H2-dominated. We have developed a photochemistry-thermochemistry kinetic-transport model for exploring the compositions of thick atmospheres ...

  4. Formation of the early atmosphere from late-accreting planetesimals Sujoy Mukhopadhyay*

    E-print Network

    Mukhopadhyay, Sujoy

    1 Formation of the early atmosphere from late-accreting planetesimals Sujoy Mukhopadhyay* , Rita, Cambridge MA 02138, USA. * Corresponding author Abstract The composition of Earth's early atmosphere strongly influenced chemical reactions on our planet's surface. For example, an early reducing atmosphere

  5. The armoured dissorophid Cacops from the Early Permian of Oklahoma and the exploitation of the terrestrial realm by amphibians

    NASA Astrophysics Data System (ADS)

    Reisz, Robert R.; Schoch, Rainer R.; Anderson, Jason S.

    2009-07-01

    Cacops, one of the most distinctive Paleozoic amphibians, is part of a clade of dissorophoid temnospondyls that diversified in the equatorial region of Pangea during the Late Carboniferous and Early Permian, persisting into the Late Permian in Central Russia and China. Dissorophids were a successful group of fully terrestrial, often spectacularly armoured predators, the only amphibians apparently able to coexist with amniotes when the latter started to dominate terrestrial ecosystems. In this paper, we describe excellent new skulls from the Early Permian of Oklahoma attributed to Cacops, Cacops morrisi sp. nov. and provide for the first time detailed information about this iconic dissorophid. These specimens show anatomical and ontogenetic features that will impact on future studies on the evolution of terrestriality in tetrapods. For example, the large, posteriorly closed tympanic embayment has fine striations on an otherwise smooth surface, documenting the oldest known clear evidence for the presence of a tympanic membrane in the fossil record, a structure that is used for hearing airborne sound in extant tetrapods. The skull of C. morrisi also has several features associated with predatory behaviour, indicating that this dissorophid may have been one of the top terrestrial predators of its time.

  6. Speciation of C-O-H volatiles in reduced magmas applicable to early terrestrial and planetary deep volatile cycles

    NASA Astrophysics Data System (ADS)

    Armstrong, Lora; Hirschmann, Marc

    2014-05-01

    The speciation and solubility of C-O-H volatiles in reduced magmas are of great importance for volatile behavior in the early Earth and other planets determining partitioning between Earth's earliest atmospheres, mantle, and cores, as well as influencing volcanogenic degassing on reduced planetary bodies such as Mars and the Moon. In mafic and ultramafic magmas, C is soluble chiefly as carbonate under oxidizing conditions, but when fO2 is below that required for graphite (or diamond) saturation, carbonate solubility diminishes severely. This has left the question as to what, if any, species may host dissolved C in magmas under reducing conditions. Initial results suggested that the principle species may be CH4 (Mysen et al. 2009), but experiments at well-defined thermodynamic conditions have shown that CH4 solubility is very small except under conditions of very high H2 fugacity (Ardia et al. 2012). More recent experiments (Wetzel et al. 2013; Stanley et al. 2014) have identified Fe-carbonyl-like species as possibly the most stable. To clarify the relative stability of these species, we have conducted additional high pressure experiments at 1.2 GPa and 1400°C with graphite-saturated martian and terrestrial (MORB) basalt compositions, over a range of oxygen fugacities, paying careful attention to the availability of H2O. FTIR and Raman analyses reveal a range of distinct species that predominate as a function of fO2 and availability of H2O. At comparatively oxidizing conditions, carbonate is the most abundant species but within 1 log unit of iron wustite (IW), carbonyl-like species predominate, provided that conditions are comparatively dry. At yet more reducing conditions, carbonyl is absent and instead N-H associated species (perhaps amides?) are more important. Methane is observed only when quenched glasses have appreciable H2O (approaching ~ 1 wt.%). In all cases, solubilities are small when conditions are reduced, with <100 ppm C at IW or below.

  7. Heat flow vs. atmospheric greenhouse on early Mars

    NASA Technical Reports Server (NTRS)

    Fanale, F. P.; Postawko, S. E.

    1991-01-01

    Researchers derived a quantitative relationship between the effectiveness of an atmospheric greenhouse and internal heat flow in producing the morphological differences between earlier and later Martian terrains. The derivation is based on relationships previously derived by other researchers. The reasoning may be stated as follows: the CO2 mean residence time in the Martian atmosphere is almost certainly much shorter than the total time span over which early climate differences are thought to have been sustained. Therefore, recycling of previously degassed CO2 quickly becomes more important than the ongoing supply of juvenile CO2. If so, then the atmospheric CO2 pressure, and thereby the surface temperature, may be approximated mathematically as a function of the total degassed CO2 in the atmosphere plus buried material and the ratio of the atmospheric and regolith mean residence times. The latter ratio can also be expressed as a function of heat flow. Hence, it follows that the surface temperature may be expressed as a function of heat flow and the total amount of available CO2. However, the depth to the water table can simultaneously be expressed as a function of heat flow and the surface temperature (the boundary condition). Therefore, for any given values of total available CO2 and regolith conductivity, there exist coupled independent equations which relate heat flow, surface temperature, and the depth to the water table. This means we can now derive simultaneous values of surface temperature and the depth of the water table for any value of the heat flow. The derived relationship is used to evaluate the relative importance of the atmospheric greenhouse effect and the internal regolith thermal gradient in producing morphological changes for any value of the heat flow, and to assess the absolute importance of each of the values of the heat flow which are thought to be reasonable on independent geophysical grounds.

  8. Responses of global terrestrial evapotranspiration to climate change and increasing atmospheric CO2 in the 21st century

    NASA Astrophysics Data System (ADS)

    Pan, Shufen; Tian, Hanqin; Dangal, Shree R. S.; Yang, Qichun; Yang, Jia; Lu, Chaoqun; Tao, Bo; Ren, Wei; Ouyang, Zhiyun

    2015-01-01

    Quantifying the spatial and temporal patterns of the water lost to the atmosphere through land surface evapotranspiration (ET) is essential for understanding the global hydrological cycle, but remains much uncertain. In this study, we use the Dynamic Land Ecosystem Model to estimate the global terrestrial ET during 2000-2009 and project its changes in response to climate change and increasing atmospheric CO2 under two IPCC SRES scenarios (A2 and B1) during 2010-2099. Modeled results show a mean annual global terrestrial ET of about 549 (545-552) mm yr-1 during 2000-2009. Relative to the 2000s, global terrestrial ET for the 2090s would increase by 30.7 mm yr-1 (5.6%) and 13.2 mm yr-1 (2.4%) under the A2 and B1 scenarios, respectively. About 60% of global land area would experience increasing ET at rates of over 9.5 mm decade-1 over the study period under the A2 scenario. The Arctic region would have the largest ET increase (16% compared with the 2000s level) due to larger increase in temperature than other regions. Decreased ET would mainly take place in regions like central and western Asia, northern Africa, Australia, eastern South America, and Greenland due to declines in soil moisture and changing rainfall patterns. Our results indicate that warming temperature and increasing precipitation would result in large increase in ET by the end of the 21st century, while increasing atmospheric CO2 would be responsible for decrease in ET, given the reduction of stomatal conductance under elevated CO2.

  9. New estimates of variations in atmospheric-terrestrial flux of water over Europe, based on regional reanalysis and multi-sensor observations

    NASA Astrophysics Data System (ADS)

    Kusche, J.; Springer, A.; Hartung, K.; Ohlwein, C.; Longuevergne, L.

    2013-12-01

    Precipitation minus evapotranspiration, the flux of water between the atmosphere and the Earth's surface, provides important information regarding the interaction of the atmosphere with the land surface. It links atmospheric and terrestrial water budgets and, thus, realizes an important boundary condition for both climate modeling and hydrological studies. Yet, due to a general lack of unbiased measurements, the atmospheric-terrestrial flux of water is poorly constrained by direct observations and rather, usually, reconstructed from data-assimilating atmospheric reanalyses. Via the terrestrial water budget equation, water storage derived from products of the Gravity Recovery and Climate Experiment (GRACE) mission combined with runoff data, can be used to assess the realism of atmospheric-terrestrial flux of water in atmospheric models. A number of studies have applied this method to global reanalysis products, with good results only for large river basins. In this study, we first assess the closure of the terrestrial water budget over a number of European river basins from the new release 5 GRACE products, after careful postprocessing and in combination with GRDC and BfG discharge data, and from precipitation minus evapotranspiration obtained from the operational analysis of the regional high-resolution NWP models COSMO-DE and -EU, a new COSMO-based reanalysis for the European CORDEX domain, the global reanalyses ERA-INTERIM and MERRA, as well as few observation-based data sets (E-OBS, GPCC, upscaled FLUXNET observations from Jung et al., 2010). This allows us to identify biases of up to 20 mm/month in the different data products, at different spatial scales down to the Oder catchment (110.000 km2). Among the atmospheric (re-) analyses, we find COSMO-EU atmosphere-terrestrial flux of water almost unbiased over Central Europe. Finally, we assess bias-corrected flux and reconstructed multi-sensor water storage variations.

  10. Climatological features of atmospheric and terrestrial water cycles in the three great Siberian rivers based on six atmospheric reanalyses and observed river discharges

    NASA Astrophysics Data System (ADS)

    Oshima, K.; Tachibana, Y.; Hiyama, T.

    2013-12-01

    The three great Siberian rivers: Lena, Yenisei and Ob Rivers, are top three discharges (R) among all rivers flowing into the Arctic Ocean and play a role as a large source of freshwater inflow. This study revealed the regional differences in some climatological features of the atmospheric and terrestrial water cycles in the Siberian rivers on the basis of the Rs observed at the mouth of the rivers and net precipitations (precipitation minus evapotranspiration, P-E) estimated from six atmospheric reanalyses. As pointed out in previous studies, it is obvious that the precipitation is a key player in the water cycles, but also the east-west contrast of evapotranspicarion over Siberia affects the climatological mean and seasonal cycle of P-E and R in each of the Siberian river basins. The moisture transports associated with the P-E are also different among the rivers. The transient (stationary) flux associated with cyclone activity (mean atmospheric flow) dominates over the Lena (Ob) River basin in the east (west). In addition to the climatological distributions of SAT, humidity and atmospheric circulation over Siberia, the geographical and terrestrial conditions of this region such as topography, distance from the ocean, mainstream of the river, permafrost and vegetation type make the unique features of the water cycles in the individual Siberian rivers. Comparison of the six atmospheric reanalyses indicated that the estimations of P-E by using the reanalyses are reasonable compared to the observed R, and that is an effective way to evaluate and quantify the water cycles in the Lena, Yenisei and Ob Rivers.

  11. Impact of atmospheric aerosol light scattering and absorption on terrestrial net primary productivity

    Microsoft Academic Search

    Daniel S. Cohan; Jin Xu; Roby Greenwald; Michael H. Bergin; William L. Chameides

    2002-01-01

    Scattering and absorption of sunlight by anthropogenic aerosols reduce the photosynthetically active radiation (PAR) incident upon the Earth's surface, but increase the fraction of the PAR that is diffuse. These alterations to irradiance may elicit conflicting responses in terrestrial plants: photosynthesis and net primary productivity (NPP) are slowed by reductions in total PAR, but enhanced by increases in diffuse PAR.

  12. Complex Propagation of Large Sound Sources in Terrestrial-like Atmospheres and its Application to Bolide Detection

    NASA Astrophysics Data System (ADS)

    Williams, Jean-pierre; McEwan, I.

    2006-09-01

    We have developed an advanced generalized, acoustic ray-tracing model to capture the behavior of sound (i.e. its radiation pattern and range of detectability) in the complex dynamical systems of the Venus, Earth, Mars, and Titan atmospheres. Sound propagation is affected by the composition, structure, and dynamics of a planet's atmosphere; therefore we have adopted a modular approach so that any hypothetical atmosphere with varying climatic conditions and gas composition can be account for. Our model determines the viscous, thermal, and molecular attenuation in a given multi-gas atmosphere as well as attenuation resulting from suspended aerosols. Given output from a global or meso-scale atmospheric model, we then ray trace the sound path accounting for these properties. As a specific application, we suggest an in-atmosphere acoustic technique for measuring bolides influx rates (which are currently highly uncertain and significantly affect results of modeled absolute crater retention ages). Bolides [explosions] provide well-characterized, large magnitude, low-frequency sound sources that are common to all planetary atmospheres and should be remotely detectable by acoustic sensors. We present an end-to-end comparison between Venus, Earth, Mars, and Titan by modeling a typical large terrestrial event and the resulting sound propagation in each environment. For each event we determine airburst altitudes, acoustic energy release, sound propagation pattern and the footprint size on the ground. From this we place constraints on the practicality of an in-situ acoustic sensor as a method for direct measurement of bolide influx rates in planetary atmospheres. This work has been supported by the Caltech O. K. Earl Postdoctoral Fellowship.

  13. Integration of ice core, marine and terrestrial records: new insights into Holocene atmospheric circulation dynamics over NW Europe

    NASA Astrophysics Data System (ADS)

    Muschitiello, F.; Hammarlund, D.; Wohlfarth, B.

    2012-12-01

    We analyzed the oxygen (?18O) and carbon (?13C) isotope composition of lacustrine carbonates (Chara sp. and Bithynia tentaculata) from a lake sediment sequence (Lake Bjärsträsk) on the island of Gotland, southern Sweden. Our new isotopic records show a significant consistency with existing regional climatic reconstructions, as well as with paleorecords reflecting large-scale circulation dynamics. By comparing our data to ice core records from Greenland and to regional- and global-scale terrestrial and marine climate records, we explore potential couplings of Mid- and Late Holocene extreme summer climate conditions in northwestern Europe to orbital forcing and low-latitude atmospheric circulation dynamics. Specifically, we discuss the relationship between long-term changes in the position of the North Atlantic subtropical front and the frequency of summer blocking anticyclones over southern Sweden. Furthermore, we tentatively outline the spatial structure of predominant modes of atmospheric variability over the North Atlantic sector throughout the Holocene.

  14. Changes in the terrestrial atmosphere-ionosphere-magnetosphere system due to ion propulsion for solar power satellite placement

    NASA Technical Reports Server (NTRS)

    Curtis, S. A.; Grebowsky, J. M.

    1979-01-01

    Preliminary estimates of the effects massive Ar(+) injections on the ionosphere-plasmasphere system with specific emphasis on potential communications disruptions are given. The effects stem from direct Ar(+) precipitation into the atmosphere and from Ar(+) beam induced precipitation of MeV radiation belt protons. These injections result from the construction of Solar Power Satellites using earth-based materials in which sections of a satellite must be lifted from low earth to geosynchronous orbit by means of ion propulsion based on the relatively abundant terrestrial atmospheric component, Ar. The total amount of Ar(+) injected in transporting the components for each Solar Power Satellite is comparable to the total ion content of the ionosphere-plasmasphere system while the total energy injected is larger than that of this system. It is suggested that such effects may be largely eliminated by using lunar-based rather than earth-based satellite construction materials.

  15. Hydraulics of Asteroxylon mackei, an early Devonian vascular plant, and the early evolution of water transport tissue in terrestrial plants.

    PubMed

    Wilson, J P; Fischer, W W

    2011-03-01

    The core of plant physiology is a set of functional solutions to a tradeoff between CO(2) acquisition and water loss. To provide an important evolutionary perspective on how the earliest land plants met this tradeoff, we constructed a mathematical model (constrained geometrically with measurements of fossils) of the hydraulic resistance of Asteroxylon, an Early Devonian plant. The model results illuminate the water transport physiology of one of the earliest vascular plants. Results show that Asteroxylon's vascular system contains cells with low hydraulic resistances; these resistances are low because cells were covered by scalariform pits, elliptical structures that permit individual cells to have large areas for water to pass from one cell to another. Asteroxylon could move a large amount of water quickly given its large pit areas; however, this would have left these plants particularly vulnerable to damage from excessive evapotranspiration. These results highlight a repeated pattern in plant evolution, wherein the evolution of highly conductive vascular tissue precedes the appearance of adaptations to increase water transport safety. Quantitative insight into the vascular transport of Asteroxylon also allows us to reflect on the quality of CO(2) proxy estimates based on early land plant fossils. Because Asteroxylon's vascular tissue lacked any safety features to prevent permanent damage, it probably used stomatal abundance and behavior to prevent desiccation. If correct, low stomatal frequencies in Asteroxylon reflect the need to limit evapotranspiration, rather than adaptation to high CO(2) concentrations in the atmosphere. More broadly, methods to reveal and understand water transport in extinct plants have a clear use in testing and bolstering fossil plant-based paleoclimate proxies. PMID:21244621

  16. XUV-exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets. Part I: atmospheric expansion and thermal escape.

    PubMed

    Erkaev, Nikolai V; Lammer, Helmut; Odert, Petra; Kulikov, Yuri N; Kislyakova, Kristina G; Khodachenko, Maxim L; Güdel, Manuel; Hanslmeier, Arnold; Biernat, Helfried

    2013-11-01

    The recently discovered low-density "super-Earths" Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent the most likely known planets that are surrounded by dense H/He envelopes or contain deep H?O oceans also surrounded by dense hydrogen envelopes. Although these super-Earths are orbiting relatively close to their host stars, they have not lost their captured nebula-based hydrogen-rich or degassed volatile-rich steam protoatmospheres. Thus, it is interesting to estimate the maximum possible amount of atmospheric hydrogen loss from a terrestrial planet orbiting within the habitable zone of late main sequence host stars. For studying the thermosphere structure and escape, we apply a 1-D hydrodynamic upper atmosphere model that solves the equations of mass, momentum, and energy conservation for a planet with the mass and size of Earth and for a super-Earth with a size of 2 R(Earth) and a mass of 10 M(Earth). We calculate volume heating rates by the stellar soft X-ray and extreme ultraviolet radiation (XUV) and expansion of the upper atmosphere, its temperature, density, and velocity structure and related thermal escape rates during the planet's lifetime. Moreover, we investigate under which conditions both planets enter the blow-off escape regime and may therefore experience loss rates that are close to the energy-limited escape. Finally, we discuss the results in the context of atmospheric evolution and implications for habitability of terrestrial planets in general. PMID:24251443

  17. Dynamic oxygenation of the early atmosphere and oceans

    NASA Astrophysics Data System (ADS)

    Lyons, Timothy W.; Planavsky, Noah J.; Reinhard, Christopher T.

    2014-05-01

    The traditional view of the oxygenation of the early atmosphere and oceans depicts irreversibly rising abundances in two large steps: one at the Great Oxidation Event (GOE) ca. 2.3-2.4 billion years ago (Ga) and another near the end of the Neoproterozoic. This talk will explore how the latest data challenge this paradigm. Recent results reveal a far more dynamic history of early oxygenation, one with both rising and falling levels, long periods of sustained low concentrations even after the GOE, complex feedback relationships that likely coupled nutrients and ocean redox, and dramatic changes tied through still-emerging cause-and-effect relationships to first-order tectonic, climatic, and evolutionary events. In the face of increasing doubt about the robustness of organic biomarker records from the Archean, researchers are increasingly reliant on inorganic geochemical proxies for the earliest records of oxygenic photosynthesis. Proxy data now suggest oxygenesis at ca. 3.0 Ga with a likelihood of local oxygen build up in the surface ocean long before the GOE, as well as low (and perhaps transient) accumulation in the atmosphere against a backdrop of mostly less than ca. 0.001% of the present atmospheric concentration. By the GOE, the balance between oxygen sources and sinks shifted in favor of persistent accumulation, although sedimentary recycling of non-mass-dependent sulfur isotope signatures allows for the possibility of rising and falling atmospheric oxygen before the GOE as traditionally defined by the sulfur isotope record. Recycling may also hinder our ability to precisely date the transition to permanent oxygen accumulation beyond trace levels. Diverse data point to a dramatic increase in biospheric oxygen following the GOE, coincident with the largest positive carbon isotope excursion in Earth history, followed by an equally dramatic drop. This decline in Earth surface redox potential ushered in more than a billion years of dominantly low oxygen levels in the atmosphere—at perhaps much less than 1% of modern levels, as suggested by new chromium isotope data—and persistent anoxia in the deep ocean with euxinia limited to productive ocean margins. Under conditions of ca. 1-10% euxinic seafloor, bioessential trace metals would have been drawn down to levels that may have deleteriously impacted the availability of fixed nitrogen in the oceans and, through associated redox-dependent feedbacks, sustained comparatively low global levels of primary production and corresponding deficiencies in biospheric oxygen. This episode of intermediate redox gave way to increases in ocean-atmosphere oxygen that appear to predate the Sturtian glaciation. Although the causes behind this transition are not well understood, they are certain to reflect relationships among large-scale tectonic, climatic, and biotic drivers of nutrient availability and organic carbon production and burial. Oxygen during the Ediacaran, following the Marinoan glaciation, likely rose and fell episodically in ways that must have impacted the diversity and ecological relationships among early animals. Also, the low oxygen concentrations purported for the mid-Proterozoic are consistent with the long-held, but recently challenged, suggestion that the rise of animals was ultimately coincident with, and likely causally related to, a Neoproterozoic rise in oxygen.

  18. Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2

    E-print Network

    Kite, Edwin

    1 Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2-dominated atmosphere, but direct constraints on paleoatmospheric11 pressure P are lacking. Of particular doubtful that increasing CO2 pressure (total atmospheric pressure, P) is enough to raise early39 Mars

  19. The Net Exchange Between Terrestrial Ecosystems and the Atmosphere as a Result of Changes in Land Use

    NASA Technical Reports Server (NTRS)

    Houghton, R. A.

    1998-01-01

    The general purpose of this research was to improve and update (to 1990) estimates of the net flux of carbon between the world's terrestrial ecosystems and the atmosphere from changes in land use (e.g., deforestation and reforestation). The estimates are important for understanding the global carbon cycle, and for predicting future concentrations of atmospheric CO2 that will result from emissions. The emphasis of the first year's research was on the northern temperate zone and boreal forests, where the greatest discrepancy exists between estimates of flux. Forest inventories suggest net sinks of 0.6 PgC/yr; inversion analyses based on atmospheric data and models suggest much larger sinks 2-3.6 PgC/yr (e.g., Tans et al. 1990, Ciais et al. 1995). The work carried out with this grant calculated the flux attributable to changes in land use. The estimated flux was somewhat smaller than the flux calculated from inventory data suggesting that environmental changes have led to a small accumulation of carbon in forests that exceeds the accumulation expected from past rates of harvest. Two publications have described these results (Houghton 1996, 1998). The large difference between these estimates and those obtained with atmospheric data and models remains unexplained. The recent estimate of a 1.7 PgC/yr sink in North America, alone (Fan et al. 1998), is particularly difficult to explain. That part of the sink attributable to land-use change, however, is defined as a result of this grant.

  20. OUTSTANDING ISSUES REGARDING THE ROLE OF ATMOSPHERIC AEROSOLS ON TERRESTRIAL BIOSPHERE AND REGIONAL CLIMATE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Atmospheric aerosols have a complex feedback on the earth’s climate. Past studies related to studying the impact of aerosols on the earth’s climate had focused on upper atmospheric processes including cloud-aerosol- radiative interactions. Recent evidence from field and model studies indicates that ...

  1. Fractionation of terrestrial neon by hydrodynamic hydrogen escape from ancient steam atmospheres

    NASA Technical Reports Server (NTRS)

    Zahnle, K.

    1991-01-01

    Atmospheric neon is isotopically heavier than mantle neon. By contrast, nonradiogenic mantle Ar, Kr, and Xe are not known to differ from the atmosphere. These observations are most easily explained by selective neon loss to space; however, neon is much too massive to escape from the modern atmosphere. Steam atmospheres are a likely, if intermittent, feature of the accreting Earth. They occur because, on average, the energy liberated during accretion places Earth above the runaway greenhouse threshold, so that liquid water is not stable at the surface. It is found that steam atmospheres should have lasted some ten to fifty million years. Hydrogen escape would have been vigorous, but abundant heavy constituents would have been retained. There is no lack of plausible candidates; CO2, N2, or CO could all suffice. Neon can escape because it is less massive than any of the likely pollutants. Neon fractionation would have been a natural byproduct. Assuming that the initial Ne-20/Ne-22 ratio was solar, it was found that it would have taken some ten million years to effect the observed neon fractionation in a 30 bar steam atmosphere fouled with 10 bars of CO. Thicker atmospheres would have taken longer; less CO, shorter. This mechanism for fractionating neon has about the right level of efficiency. Because the lighter isotope escapes much more readily, total neon loss is pretty minimal; less than half of the initial neon endowment escapes.

  2. Estimating Terrestrial Water Storage Changes in the Colorado River Basin: Atmospheric Data Analysis, Satellite Remote Sensing and Hydrologic Modeling

    NASA Astrophysics Data System (ADS)

    Troch, P. A.; Seneviratne, S.; Hirschi, M.; Hurkmans, R.; Hasan, S.; Durcik, M.

    2006-12-01

    The Colorado River basin covers about 637 000 km2 and spreads over the southwestern United States and a small portion of Mexico. Much of the basin is arid, and runoff derives from the high elevation snow pack over the Rocky Mountains, which contributes about 70% of the annual runoff. A secondary source of water for the basin is the summer monsoon precipitation. The Colorado River system is one of the most heavily regulated for providing water supply, irrigation, flood control, and hydropower to a large area of the U.S. Southwest. Estimating intra- and inter-annual variability of water storage in the basin is important for sustainable water management. In this paper, an overview is given on how terrestrial water storage changes can be estimated. Fifty (50) years (1955-2005) of re-analysis data from ECMWF (European Center for Medium Range Weather Forecasts) is used together with observed and natural stream flow to derive monthly atmospheric and terrestrial water balances (Seneviratne et al., 2004; Hirschi et al., 2006). The resulting water storage changes in the Colorado basin exhibit a strong annual and a weaker decadal cycle. Correlation with different climate variability indices (ENSO, PDO, AMO) is examined. We compare these water storage change estimates with those derived from the NARR (North-American Regional Re-analysis) time series (1979 to 2005). Three years (2002-2005) of GRACE (Gravity Recovery and Climate Experiment) satellite data are then used to estimate monthly terrestrial water storage changes from estimates of geoid anomalies over the area. We find a close relationship between both independent estimation procedures. Both the annual cycle and the amplitude agree very well, although a slight phase shift of about a month is observed. To further examine the water storage changes we apply a land surface hydrologic model (VIC: Variable Infiltration Capacity) forced with observations spanning the period between 1950 and 2000 and compiled by Maurer et al. (2002).

  3. The early development of Gastrotheca riobambae and Colostethus machalilla, frogs with terrestrial reproductive modes

    NSDL National Science Digital Library

    Eugenia del Pino (Pontificia Universidad Catolica del Ecuador Biology)

    2005-04-27

    A Lecture (in English) on using two local (Equador) terrestrial frogs to learn about development; from the Model Organisms and Innovative Approaches in Developmental Biology Short Course in Sao Paolo, Brazil, April 2005. These are the PPT slides only, no associated audio or text is available.

  4. A Lookup Table to Compute High Energy Cosmic Ray Effects on Terrestrial Atmospheric Chemistry

    E-print Network

    Atri, Dimitra

    2009-04-27

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software ...

  5. Transient simulations of Holocene atmospheric carbon dioxide and terrestrial carbon since the Last Glacial Maximum

    Microsoft Academic Search

    Fortunat Joos; Stefan Gerber; I. C. Prentice; Bette L. Otto-Bliesner; Paul J. Valdes

    2004-01-01

    Conflicting hypotheses are investigated for the observed atmospheric CO2 increase of 20 ppm between 8 ka BP and pre-industrial time. The carbon component of the Bern Carbon Cycle Climate (Bern CC) model, which couples the Lund-Potsdam-Jena Dynamic Global Vegetation Model to an atmosphere-ocean-sediment component, is driven by climate fields from time-slice simulations of the past 21 ka with the Hadley

  6. Carbon in the atmosphere and terrestrial biosphere in the 21st century

    Microsoft Academic Search

    Yadvinder Malhi

    2002-01-01

    The release of carbon dioxide from fossil-fuel combustion and land-use change has caused a significant perturbation in the natural cycling of carbon between land, atmosphere and oceans. Understanding and managing the effects of this disruption on atmospheric composition and global climate are likely to be amongst the most pressing issues of the 21st century. However, the present-day carbon cycle is

  7. Using atmospheric observations to evaluate the spatiotemporal variability of CO2 fluxes simulated by terrestrial biospheric models

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Michalak, A. M.; Shiga, Y. P.; Yadav, V.

    2014-06-01

    Terrestrial biospheric models (TBMs) are used to extrapolate local observations and process-level understanding of land-atmosphere carbon exchange to larger regions, and serve as a predictive tool for examining carbon-climate interactions. Understanding the performance of TBMs is thus crucial to the carbon cycle and climate science. In this study, we propose a statistical model selection approach for evaluating the spatiotemporal patterns of net ecosystem exchange (NEE) simulated by TBMs using atmospheric CO2 measurements. We find that current atmospheric observations are sensitive to the underlying spatiotemporal flux variability at sub-biome scales for a large portion of the North American continent, and that atmospheric observations can therefore be used to evaluate simulated spatiotemporal flux patterns, rather than focusing solely on flux magnitudes at aggregated scales. Results show that the proposed approach can be used to assess whether a TBM represents a substantial portion of the underlying flux variability as well as to differentiate among multiple competing TBMs. When applying the proposed approach to four prototypical TBMs, we find that the performance of TBMs varies substantially across seasons, with best performance during the growing season and limited skill during transition seasons. This seasonal difference in the ability of TBMs to represent the spatiotemporal flux variability may reflect the models' capability to represent the seasonally-varying influence of environmental drivers on fluxes. While none of the TBMs consistently outperforms the others, differences among the examined models are at least partially attributable to their internal structures. Overall, the proposed approach provides a new avenue for evaluating TBM performance based on sub-biome scale flux patterns, presenting an opportunity for assessing and informing model development using atmospheric observations.

  8. The development of GPS TroWav tool for atmospheric - terrestrial studies

    NASA Astrophysics Data System (ADS)

    Suparta, W.

    2014-04-01

    We have developed an efficient tool to process dual-frequency Global Positioning System (GPS) signals and the surface meteorological data, called the Tropospheric Water Vapor (TroWav) program. TroWav is a stand-alone program to compute atmospheric precipitable water vapor (PWV). The source of the program is developed using MatlabTM and the graphical user interface for the system was developed using a Visual Basic. The algorithms of the program capable to compute satellite elevation angle, Zenith Tropospheric Delay (ZTD), Zenith Hydrostatic Delay (ZHD), Zenith Wet Delay (ZWD) and mapping function. The tool is very practical and useful for sustainable atmospheric management.

  9. The Late Permian herbivore Suminia and the early evolution of arboreality in terrestrial vertebrate ecosystems

    PubMed Central

    Fröbisch, Jörg; Reisz, Robert R.

    2009-01-01

    Vertebrates have repeatedly filled and partitioned the terrestrial ecosystem, and have been able to occupy new, previously unexplored habitats throughout their history on land. The arboreal ecospace is particularly important in vertebrate evolution because it provides new food resources and protection from large ground-dwelling predators. We investigated the skeletal anatomy of the Late Permian (approx. 260 Ma) herbivorous synapsid Suminia getmanovi and performed a morphometric analysis of the phalangeal proportions of a great variety of extant and extinct terrestrial and arboreal tetrapods to discern locomotor function and habitat preference in fossil taxa, with special reference to Suminia. The postcranial anatomy of Suminia provides the earliest skeletal evidence for prehensile abilities and arboreality in vertebrates, as indicated by its elongate limbs, intrinsic phalangeal proportions, a divergent first digit and potentially prehensile tail. The morphometric analysis further suggests a differentiation between grasping and clinging morphotypes among arboreal vertebrates, the former displaying elongated proximal phalanges and the latter showing an elongation of the penultimate phalanges. The fossil assemblage that includes Suminia demonstrates that arboreality and resource partitioning occurred shortly after the initial establishment of the modern type of terrestrial vertebrate ecosystems, with a large number of primary consumers and few top predators. PMID:19640883

  10. The seasonal exchange of carbon dioxide between the atmosphere and the terrestrial biosphere: Extrapolation from site-specific models to regional models

    SciTech Connect

    King, A.W.; DeAngelis, D.L.; Post, W.M.

    1987-12-01

    Ecological models of the seasonal exchange of carbon dioxide (CO/sub 2/) between the atmosphere and the terrestrial biosphere are needed in the study of changes in atmospheric CO/sub 2/ concentration. In response to this need, a set of site-specific models of seasonal terrestrial carbon dynamics was assembled from open-literature sources. The collection was chosen as a base for the development of biome-level models for each of the earth's principal terrestrial biomes or vegetation complexes. The primary disadvantage of this approach is the problem of extrapolating the site-specific models across large regions having considerable biotic, climatic, and edaphic heterogeneity. Two methods of extrapolation were tested. 142 refs., 59 figs., 47 tabs

  11. Transient simulations of Holocene atmospheric carbon dioxide and terrestrial carbon since the Last Glacial Maximum

    Microsoft Academic Search

    Fortunat Joos; Stefan Gerber; I. C. Prentice; Bette L. Otto-Bliesner; Paul J. Valdes

    2004-01-01

    Conflicting hypotheses are investigated for the observed atmospheric CO2 increase of 20 ppm between 8 ka BP and preindustrial time. The carbon component of the Bern Carbon Cycle Climate (Bern CC) model, which couples the LundPotsdamJena Dynamic Global Vegetation Model to an atmosphereoceansediment component, is driven by climate fields from timeslice simulations of the past 21 ka with the Hadley

  12. Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid.

    PubMed

    Donaldson, Melissa A; Bish, David L; Raff, Jonathan D

    2014-12-30

    Nitrous acid (HONO) is an important hydroxyl (OH) radical source that is formed on both ground and aerosol surfaces in the well-mixed boundary layer. Recent studies report the release of HONO from nonacidic soils, although it is unclear how soil that is more basic than the pKa of HONO (? 3) is capable of protonating soil nitrite to serve as an atmospheric HONO source. Here, we used a coated-wall flow tube and chemical ionization mass spectrometry (CIMS) to study the pH dependence of HONO uptake onto agricultural soil and model substrates under atmospherically relevant conditions (1 atm and 30% relative humidity). Experiments measuring the evolution of HONO from pH-adjusted surfaces treated with nitrite and potentiometric titrations of the substrates show, to our knowledge for the first time, that surface acidity rather than bulk aqueous pH determines HONO uptake and desorption efficiency on soil, in a process controlled by amphoteric aluminum and iron (hydr)oxides present. The results have important implications for predicting when soil nitrite, whether microbially derived or atmospherically deposited, will act as a net source or sink of atmospheric HONO. This process represents an unrecognized mechanism of HONO release from soil that will contribute to HONO emissions throughout the day. PMID:25512517

  13. Atmospheric pressure as a natural climate regulator for a terrestrial planet with a biosphere

    PubMed Central

    Li, King-Fai; Pahlevan, Kaveh; Kirschvink, Joseph L.; Yung, Yuk L.

    2009-01-01

    Lovelock and Whitfield suggested in 1982 that, as the luminosity of the Sun increases over its life cycle, biologically enhanced silicate weathering is able to reduce the concentration of atmospheric carbon dioxide (CO2) so that the Earth's surface temperature is maintained within an inhabitable range. As this process continues, however, between 100 and 900 million years (Ma) from now the CO2 concentration will reach levels too low for C3 and C4 photosynthesis, signaling the end of the solar-powered biosphere. Here, we show that atmospheric pressure is another factor that adjusts the global temperature by broadening infrared absorption lines of greenhouse gases. A simple model including the reduction of atmospheric pressure suggests that the life span of the biosphere can be extended at least 2.3 Ga into the future, more than doubling previous estimates. This has important implications for seeking extraterrestrial life in the Universe. Space observations in the infrared region could test the hypothesis that atmospheric pressure regulates the surface temperature on extrasolar planets. PMID:19487662

  14. Atmospheric pressure as a natural climate regulator for a terrestrial planet with a biosphere.

    PubMed

    Li, King-Fai; Pahlevan, Kaveh; Kirschvink, Joseph L; Yung, Yuk L

    2009-06-16

    Lovelock and Whitfield suggested in 1982 that, as the luminosity of the Sun increases over its life cycle, biologically enhanced silicate weathering is able to reduce the concentration of atmospheric carbon dioxide (CO(2)) so that the Earth's surface temperature is maintained within an inhabitable range. As this process continues, however, between 100 and 900 million years (Ma) from now the CO(2) concentration will reach levels too low for C(3) and C(4) photosynthesis, signaling the end of the solar-powered biosphere. Here, we show that atmospheric pressure is another factor that adjusts the global temperature by broadening infrared absorption lines of greenhouse gases. A simple model including the reduction of atmospheric pressure suggests that the life span of the biosphere can be extended at least 2.3 Ga into the future, more than doubling previous estimates. This has important implications for seeking extraterrestrial life in the Universe. Space observations in the infrared region could test the hypothesis that atmospheric pressure regulates the surface temperature on extrasolar planets. PMID:19487662

  15. Using dimers to measure biosignatures and atmospheric pressure for terrestrial exoplanets.

    PubMed

    Misra, Amit; Meadows, Victoria; Claire, Mark; Crisp, Dave

    2014-02-01

    We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 ?m dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bar and for O2 volume mixing ratios above 50% of Earth's present-day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 ?m and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We also performed detectability studies for JWST transit transmission spectroscopy and found that the 1.06 and 1.27??m dimer features could be detectable (SNR>3) for an Earth analogue orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis. We calculated the required signal-to-noise ratios to detect and characterize O2 monomer and dimer features in direct imaging-reflected spectra and found that signal-to-noise ratios greater than 10 at a spectral resolving power of R=100 would be required. PMID:24432758

  16. Using Dimers to Measure Biosignatures and Atmospheric Pressure for Terrestrial Exoplanets

    NASA Astrophysics Data System (ADS)

    Misra, Amit; Meadows, Victoria; Claire, Mark; Crisp, Dave

    2014-02-01

    We present a new method to probe atmospheric pressure on Earthlike planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earthlike atmospheres, and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers, and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 $\\mu$m dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bars, and for O2 volume mixing ratios above 50% of Earth's present day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 $\\mu$m, and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We have also performed detectability studies for JWST transit transmission spectroscopy and find that the 1.06 $\\mu$m and 1.27 $\\mu$m dimer features could be detectable (SNR$>$3) for an Earth-analog orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet, and serve as biosignatures for oxygenic photosynthesis. We have calculated the required signal-to-noise ratios (SNRs) to detect and characterize O2 monomer and dimer features in reflected spectra and find that SNRs greater than 10 at a spectral resolving power of R=100 would be required.

  17. Journal of Atmospheric and Solar-Terrestrial Physics 69 (2007) 256264 Solar wind--magnetosphere coupling: A review of recent results

    E-print Network

    Bergen, Universitetet i

    Journal of Atmospheric and Solar-Terrestrial Physics 69 (2007) 256­264 Solar wind--magnetosphere May 2006 Available online 25 January 2007 Abstract This paper reviews some aspects of solar wind­magnetosphere. It is demonstrated how the state of the magnetosphere and the prior driving affect the amount of energy input

  18. Net primary production of terrestrial ecosystems in China and its equilibrium responses to changes in climate and atmospheric CO2 concentration

    Microsoft Academic Search

    X. Xiao; J. M. Melillo; D. W. Kicklighter; Y. Pan; A. D. McGuire; J. Helfrich

    We used the Terrestrial Ecosystem Model (TEM, version 4.0) to estimate net primary production (NPP) in China for contemporary climate and NPP responses to elevated CO 2 and climate changes projected by three atmospheric general circulation models (GCMs): Goddard Institute for Space Studies (GISS), Geophysical Fluid Dynamic Laboratory (GFDL) and Oregon State University (OSU). For contemporary climate at 312.5 ppmv

  19. Evidence for propagation of aerobic bacteria in particles suspended in gaseous atmospheres. [Terrestrial microorganism contamination of Jupiter atmosphere

    NASA Technical Reports Server (NTRS)

    Dimmick, R. L.; Chatigny, M. A.; Wolochow, H.; Straat, P.

    1977-01-01

    One factor involved in the possibility that airborne microbes might contaminate the Jovian atmosphere is whether microbes have the capacity to propagate in air. Prior to these studies, the evidence was that the airborne state was lethal to microbes. An aerosol of aerobic bacteria was mixed with another containing C-14-glucose, and the presence of C-14-CO2 was subsequently detected, which indicates that the airborne cells were metabolically active. In the same type of experiment, it was shown that thymidine was incorporated into the acid-insoluble fraction of samples, indicating the formation of DNA. It was also shown, both by an increase in the numbers of viable cells and a parallel increase in particle numbers, that at least two new generations of cells could occur. Evidence for propagation of anaerobic bacteria has so far been negative.

  20. Modeling Terrestrial Hydrological Systems at the Continental Scale: Testing the Accuracy of an Atmospheric GCM.

    NASA Astrophysics Data System (ADS)

    Coe, Michael T.

    2000-02-01

    A global hydrological routing algorithm (HYDRA) that simulates seasonal river discharge and changes in surface water level on a spatial resolution of 5 long × 5 lat is presented. The model is based on previous work by M. T. Coe and incorporates major improvements from that work including 1) the ability to simulate monthly and seasonal variations in discharge and lake and wetland level, and 2) direct representation of man-made dams and reservoirs. HYDRA requires as input daily or monthly mean averages of runoff, precipitation, and evaporation either from GCM output or observations.As an example of the utility of HYDRA in evaluating GCM simulations, the model is forced with monthly mean estimates of runoff from the National Centers for Environmental Prediction (NCEP) reanalysis dataset. The simulated river discharge clearly shows that although the NCEP runoff captures the large-scale features of the observed terrestrial hydrology, there are numerous differences in detail from observations. The simulated mean annual discharge is within ±20% at only 13 of 90 fluvial gauging stations compared. In general, the discharge is overestimated for most of the northern high latitudes, midcontinental North America, eastern Europe, central and eastern Asia, India, and northern Africa. Only in western Europe and eastern North America is the discharge consistently underestimated. Although there appears to be a need for improved simulation of land surface physics in the NCEP product and parameterization of flow velocities within HYDRA, the timing of the monthly mean discharge is in fair agreement with the observations.Including lakes within HYDRA reduces the amplitude of the seasonal cycle of discharge and the magnitude of the annual mean discharge of the St. Lawrence River system, in qualitative agreement with the observations. In addition, including the wetlands of the Sudd reduces the magnitude of the simulated annual discharge of the Nile River to values in better agreement with observations.Finally, the impact of man-made dams and their reservoirs on the magnitude of monthly mean discharge can be explicitly included within HYDRA. As an example, including dams and reservoirs on the Parana River improves the agreement of the simulated mean monthly discharge with observations by reducing the amplitude of the seasonal cycle to values in good agreement with the observations.The results of this study show that, although improvements can be obtained through better representations of flow velocities and more accurate digital elevation models, HYDRA can be a powerful tool for diagnosing simulated terrestrial hydrology and investigations of global climate change.

  1. The oxidation state of Hadean magmas and implications for early Earth's atmosphere.

    PubMed

    Trail, Dustin; Watson, E Bruce; Tailby, Nicholas D

    2011-12-01

    Magmatic outgassing of volatiles from Earth's interior probably played a critical part in determining the composition of the earliest atmosphere, more than 4,000 million years (Myr) ago. Given an elemental inventory of hydrogen, carbon, nitrogen, oxygen and sulphur, the identity of molecular species in gaseous volcanic emanations depends critically on the pressure (fugacity) of oxygen. Reduced melts having oxygen fugacities close to that defined by the iron-wüstite buffer would yield volatile species such as CH(4), H(2), H(2)S, NH(3) and CO, whereas melts close to the fayalite-magnetite-quartz buffer would be similar to present-day conditions and would be dominated by H(2)O, CO(2), SO(2) and N(2) (refs 1-4). Direct constraints on the oxidation state of terrestrial magmas before 3,850?Myr before present (that is, the Hadean eon) are tenuous because the rock record is sparse or absent. Samples from this earliest period of Earth's history are limited to igneous detrital zircons that pre-date the known rock record, with ages approaching ?4,400?Myr (refs 5-8). Here we report a redox-sensitive calibration to determine the oxidation state of Hadean magmatic melts that is based on the incorporation of cerium into zircon crystals. We find that the melts have average oxygen fugacities that are consistent with an oxidation state defined by the fayalite-magnetite-quartz buffer, similar to present-day conditions. Moreover, selected Hadean zircons (having chemical characteristics consistent with crystallization specifically from mantle-derived melts) suggest oxygen fugacities similar to those of Archaean and present-day mantle-derived lavas as early as ?4,350?Myr before present. These results suggest that outgassing of Earth's interior later than ?200?Myr into the history of Solar System formation would not have resulted in a reducing atmosphere. PMID:22129728

  2. Impact of Aquatic and Terrestrial Emissions on Atmospheric N2O Variability

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Riddick, S. N.; Saikawa, E.; Hess, P. G.

    2013-12-01

    Atmospheric concentrations of the greenhouse gas nitrous oxide (N2O) have increased by about 20% since the preindustrial era, an increase that has been driven largely by use of anthropogenic nitrogen fertilizers. The N2O source associated with agriculture was historically underestimated by assessments that considered only direct emissions from fertilized fields, but more recently it has been recognized that 'indirect' emissions associated with N leaching and runoff to rivers and may account for as much as half of total agricultural N2O emissions. Meanwhile, recent regional atmospheric N2O inversions have inferred large North American agricultural N2O sources that are difficult to reconcile with global budget constraints. At the same time, it is not clear whether the inversions can detect indirect N2O emissions associated with nitrogen leaching and runoff. Here, we will present forward model simulations aimed at quantifying the relative magnitude, spatial distribution and timing of direct and indirect agricultural N2O emissions. The model simulations will be based on the Community Land Model (CLM), with new agricultural and trace N gas parameterizations, coupled to the River Transport Model (RTM), with a module for estimating river N transport and N2O production associated with in-stream sediment denitrification. The coupled CLM-RTM N2O fluxes will be used to force atmospheric chemistry tracer transport model (ACTM) simulations, with direct and indirect emissions carried as separate tracers. The ACTM results will be used to evaluate the impact of both types of emissions on site-specific variability in atmospheric N2O at United States monitoring sites and to assess the likelihood that current atmospheric monitoring networks can detect these signals. Locations of selected NOAA monitoring sites for atmospheric N2O over the continental United States, showing both aircraft (triangles) and surface flask or tower sites (filled circles). Site locations are superimposed on a map of present-day N fertilizer use, one of the primary drivers of N2O fluxes in our CLM-RTM simulations.

  3. Observed and Modeled Tritium Concentrations in the Terrestrial Food Chain near a Continuous Atmospheric Source

    SciTech Connect

    Davis, P.A.; Kim, S.B.; Chouhan, S.L.; Workman, W.J.G. [Atomic Energy of Canada Limited (Canada)

    2005-07-15

    Tritium concentrations were measured in a large number of environmental and biological samples collected during 2002 at two dairy farms and a hobby farm near Pickering Nuclear Generating Station in Ontario, Canada. The data cover most compartments of the terrestrial food chain in an agricultural setting and include detailed information on the diets of the local farm animals. Ratios of plant OBT concentration to air moisture HTO varied between 0.12 and 0.56, and were generally higher for the forage crops collected at the dairy farms than for the garden vegetables sampled at the hobby farm. Animal OBT to air HTO ratios were more uniform, ranging from 0.18 to 0.45, and were generally higher for the milk and beef samples from the dairy farms than for the chicken products from the hobby farm. The observed OBT concentrations in plants and animals were compared with predictions of IMPACT, the model used by the Canadian nuclear industry to calculate annual average doses due to routine releases. The model performed well on average for the animal endpoints but overestimated concentrations in plants by a factor of 2.

  4. Implications of present-day abiogenic methane fluxes for the early Archean atmosphere

    E-print Network

    Simon, Emmanuel

    to the estab- lishment of biological methanogenic pathways. In present- day Earth, there are three main sourcesImplications of present-day abiogenic methane fluxes for the early Archean atmosphere Simon August 2007. [1] During Earth's early history, greenhouse warming by atmospheric methane helped

  5. Global N2O cycles - Terrestrial emissions, atmospheric accumulation and biospheric effects

    NASA Technical Reports Server (NTRS)

    Banin, A.; Lawless, J. G.; Whitten, R. C.

    1984-01-01

    Recent findings concerning the budget and cycles of nitrous oxide on earth are summarized, and the sources and sinks for N2O on land, in the ocean, and in the atmosphere are examined in view of the N2O concentration increase of 0.2-0.4 percent per year, observed over the period of 1975-1982. Possible atmospheric and biospheric consequences of the N2O concentration increase are evaluated. N2O emission values are given for several major ecosystem types, such as forest, desert, cultivated land; values from different sources are compared and discussed. Analysis shows an excess of documented sources over sinks by 0-51 Tg N2O-N/yr.

  6. Terrestrial potassium and argon abundances as limits to models of atmospheric evolution

    Microsoft Academic Search

    D. E. Fisher

    1978-01-01

    A study has been made of internal-earth abundances of potassium and argon, noting calculations which set limits to models of atmospheric evolution. Approximations for world-wide mantle abundances are given as Ar-40\\/Ar-36 of about 1.5 x 10 to the 4th and K of between 85 and 850 ppm. Consideration is given to models of continuous degassing and of K transport from

  7. Verification of Atmospheric Signals Associated with Major Seismicity by Space and Terrestrial Observations

    NASA Astrophysics Data System (ADS)

    Ouzounov, D.; Pulinets, S.; Taylor, P.; Bryant, N.; Cervone, G.; Kafatos, M.; Habib, S.

    2008-12-01

    Observations from the last twenty years suggest the existence of electromagnetic (EM) phenomena during or preceding some earthquakes [Hayakawa et al, 2004; Pulinets at al, 1999,2004, 2006, Ouzounov et al, 2007 and Liu et al, 2004]. Both our previous studies [Pulinets at al, 2005, 2006, Ouzounov et al, 2006, 2007] and the latest review by the Earthquake Remote Precursor Sensing panel [ERPS; 2003-2005]; have shown that there were precursory atmospheric TIR signals observed on the ground and in space associated with several recent earthquakes. [Tramutoli et al, 2005, 2006, Cervone et al, 2006, Ouzounov et al, 2004,2006]. To study these signals, we applied both multi parameter statistical analysis and data mining methods that require systematic measurements from an Integrated Sensor Web of observations of several physical and environmental parameters. These include long wave earth infra-red radiation, ionospheric electrical and magnetic parameters, temperature and humidity of the boundary layer, seismicity and may be associated with major earthquakes. Our goal is to verify the earthquake atmospheric correlation in two cases: (i) backward analysis - 2000-2008 hindcast monitoring of multi atmospheric parameters over the Kamchatka region, Russia ; and (ii) forward real-time alert analysis over different seismo-tectonic regions for California, Turkey, Taiwan and Japan. Our latest results, from several post-earthquake independent analyses of more then 100 major earthquakes, show that joint satellite and some ground measurements, using an integrated web, could provide a capability for observing pre-earthquake atmospheric signals by combining the information from multiple sensors into a common framework. Using our methodology, we evaluated and compared the observed signals preceding the latest M7.9 Sichuan earthquake (05/12/2008), M8.0 earthquake in Peru (08/15/2007), M7.6 Kashmir earthquake (10/08/2005) and M9.0 Sumatra earthquake (12/26/2004). We found evidence of the systematic appearance of both atmospheric and ionospheric anomalies preceding most of the major events during the period of our analysis 2001-2008.

  8. Variations in Solar Activity and Irradiance and Their Implications for Energy Input Into the Terrestrial Atmosphere

    NASA Astrophysics Data System (ADS)

    Parker, Daryl Gray

    This dissertation presents research into the question of how variations in the physical properties of resolved solar magnetic surface features combine to produce variations in the physical properties of the integrated Sun and the possible impacts of those variations on the terrestrial climate system. The core approach to the research was development of techniques to apply automated Bayesian statistical pattern recognition methods as implemented in the AutoClass software to magnetic and intensity-like solar images from the Mount Wilson Solar Observatory (MWO) 150 Foot Solar Telescope. The goals were to: (1) identify in an objective and quantifiable manner the solar surface features responsible for changes in solar irradiance, (2) enhance understanding of the evolution of these features and the resultant solar irradiance variations over the most recent solar cycles, (3) develop methods to identify the specific features responsible for variations in specific wavelengths, (4) use global observations of global solar irradiance indices to identify the spatially resolved features which contribute to them, (5) attempt to apply these results to specific topics of current interest in solar-stellar astronomy. Using these techniques, a method was developed to identify classes of features from thousands of MWO solar images based on the per pixel values of absolute magnetic field strength and an intensity measure known as a "ratio-gram" in MWO images. Using these classes along with observations from independent, usually satellite based, sources in different wavelengths, models were constructed of total solar irradiance (TSI) and solar UV indices. These models were able to reproduce with high correlations solar observations in a number of different solar wavelengths. These classes were also used to construct images mapping different wavelength emissions to the areas to the solar surface features from which they originated. These techniques proved able to reproduce with high accuracy many of the different wavelengths comprising solar irradiance and to identify the features producing them on the solar surface. The results of this research imply constraints on the fraction of variations in solar TSI and other wavelength emissions which can be accounted for by magnetic field variations without resort to other explanatory mechanisms. These findings in turn imply constraints on the extent to which variations in solar irradiance may be a factor contributing to observed global warming. These findings include: (1) constraining possible non-magnetic sources of TSI variations to a range of 5--6% versus 10--20% in earlier research, suggesting a limitation on solar TSI forcing of terrestrial climate to the 0.1% solar cycle variations in magnetic activity and (2) a failure to find an upward minimum to minimum trend in TSI from Cycle 21/22 to 22/23 such as reported by others and the detection of a downward trend from the Cycle 22/23 to 23/24 minimum. The results are also useful diagnostics for the inference of the surface properties study of solar-type stars for which resolved spatial images are not available.

  9. The National Ecological Observatory Network's Atmospheric and Terrestrial Instrumentation: Quality Control Approaches

    NASA Astrophysics Data System (ADS)

    Taylor, J. R.; Luo, H.; Ayres, E.; Metzger, S. R.; Loescher, H. W.

    2012-12-01

    The National Ecological Observatory Network's Fundamental Instrument Unit (NEON-FIU) is responsible for making automated terrestrial observations at 60 different sites across the continent. FIU will provide data on key local physical, chemical, and climate forcing, as well as associated biotic responses (CO2, H2O, and energy exchanges). The sheer volume of data that will be generated far exceeds that of any other observatory network or agency, (i.e., > 45 Tb/year from 10's of thousands of remotely deployed sensors). We address the question of how to develop and implement a large ecological observatory that can accommodate such a large volume of data while maintaining high quality. Here, we describe our quality assurance and quality control (QA/QC) program to produce quality data while leveraging cyber infrastructure tools and optimizing technician time. Results focus on novel approaches that advance the quality control techniques that have been historically employed in other networks (DOE-ARM, AmeriFlux, USDA ARS, OK Mesonet) to new state-of-the-art functionality. These automated and semi-automated approaches are also used to inform automated problem tracking to efficiently deploy field staff. Ultimately, NEON will define its own standards for QA/QC and maintenance by building upon these existing frameworks. The overarching philosophy relies on attaining the highest levels of accuracy, precision, and operational time, while efficiently optimizing the effort needed to produce quality data products. Our preliminary results address the challenges associated with automated implementation of sensor command/control, plausibility testing, despiking, and data verification of FIU observations.

  10. Linelist of HD16O for study of atmosphere of terrestrial planets (Earth, Venus and Mars)

    NASA Astrophysics Data System (ADS)

    Lavrentieva, N. N.; Voronin, B. A.; Naumenko, O. V.; Bykov, A. D.; Fedorova, A. A.

    2014-07-01

    Studies of water vapor in the atmospheres of Venus, Mars and Earth by spectroscopic techniques are being made routinely with different instruments on board of interplanetary missions like Mars-Express, Venus-Express and many others as well as with a lot of spacecrafts on the Earth’ orbit. Accessibility of detailed spectroscopic information in a wide range is then of crucial importance to retrieve reliable results with these instruments. Unlike Earth, Mars and Venus have the CO2-rich planetary atmospheres that require line shape parameters for HDO-CO2 broadening. In this paper a new linelist for HD16O is presented. This linelist covers the range of 0.00065-25,660 cm-1 and is significantly more complete than other databases presently available. All lines with intensities (for 100% abundance) greater than 10-30 cm/molecule at 296 K are included. Wavenumbers for 43% (about 300,000) of all lines were evaluated at a level of the best experimental accuracy. For each transition the line shape parameters such as halfwidth and temperature exponent are provided for the case of HDO-air, HDO-HDO, and HDO-CO2 broadening. The final linelist contains more than 700,000 HD16O lines and is presented in HITRAN-compatible format.

  11. The production of trace gases by photochemistry and lightning in the early atmosphere

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Tennille, G. M.; Towe, K. M.; Khanna, R. K.

    1986-01-01

    Recent atmospheric calculation suggest that the prebiological atmosphere was most probably composed of nitrogen, carbon dioxide, and water vapor, resulting from volatile outgassing, as opposed to the older view of a strongly reducing early atmosphere composed of methane, ammonia, and hydrogen. Photochemical calculations indicate that methane would have been readily destroyed via reaction with the hydroxyl radical produced from water vapor and that ammonia would have been readily lost via photolysis and rainout. The rapid loss of methane and ammonia, coupled with the absence of a significant source of these gases, suggest that atmospheric methane and ammonia were very short lived, if they were present at all. An early atmosphere of N2, CO2, and H2O is stable and leads to the chemical production of a number of atmospheric species of biological significance, including oxygen, ozone, carbon monoxide, formaldehyde, and hydrogen cyanide. Using a photochemical model of the early atmosphere, the chemical productionof these species over a wide range of atmospheric parameters were investigated. These calculations indicate that early atmospheric levels of O3 were significantly below the levels needed to provide UV shielding. The fate of volcanically emitted sulfur species, e.g., sulfur dioxide and hydrogen sulfide, was investigated in the early atmosphere to assess their UV shielding properties. The photochemical calculations show that these species were of insufficient levels, due in part to their short photochemical lifetimes, to provide UV shielding.

  12. Transit Observations of Venus's Atmosphere in 2012 from Terrestrial and Space Telescopes as Exoplanet Analogs

    NASA Astrophysics Data System (ADS)

    Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.; Penn, M. J.; Jaeggli, S. A.; Galayda, E.; Reardon, K. P.; Widemann, T.; Tanga, P.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson, P. D.; Dantowitz, R.

    2013-06-01

    We extensively observed the 8 June 2012 transit of Venus from several sites on Earth; we provide this interim status report about this and about two subsequent ToVs observed from space. From Haleakala Obs., we observed the entire June transit over almost 7 h with a coronagraph of the Venus Twilight Experiment B filter) and with a RED Epic camera to compare with simultaneous data from ESA's Venus Express, to study the Cytherean mesosphere; from Kitt Peak, we have near-IR spectropolarimetry at 1.6 µm from the aureole and during the disk crossing that compare well with carbon dioxide spectral models; from Sac Peak/IBIS we have high-resolution imaging of the Cytherean aureole for 22 min, starting even before 1st contact; from Big Bear, we have high-resolution imaging of Venus's atmosphere and the black-drop effect through 2nd contact; and we had 8 other coronagraphs around the world. For the Sept 21 ToV as seen from Jupiter, we had 14 orbits of HST to use Jupiter's clouds as a reflecting surface to search for an 0.01% diminution in light and a differential drop that would result from Venus's atmosphere by observing in both IR/UV, for which we have 170 HST exposures. As of this writing, preliminary data reduction indicates that variations in Jovian clouds and the two periods of Jupiter's rotation will be too great to allow extraction of the transit signal. For the December 20 ToV as seen from Saturn, we had 22 hours of observing time with VIMS on Cassini, for which we are looking for a signal of the 10-hr transit in total solar irradiance and of Venus's atmosphere in IR as an exoplanet-transit analog. Our Maui & Sac Peak expedition was sponsored by National Geographic Society's Committee for Research and Exploration; HST data reduction by NASA: HST-GO-13067. Some of the funds for the carbon dioxide filter for Sac Peak provided by NASA through AAS's Small Research Grant Program. We thank Rob Ratkowski of Haleakala Amateur Astronomers; Rob Lucas, Aram Friedman, Eric Pilger, Stan Truitt, and Steve Bisque/Software Bisque for Haleakala support/operations; Vasyl Yurchyshyn and Joseph Gangestad '06 of The Aerospace Corp. at Big Bear Solar Obs; LMSAL and Hinode science/operations team.

  13. Transfer of visible and infra-red radiation through the terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Mitra, S. K.

    1980-03-01

    The transfer is considered with a view towards answering the following two questions: can radiation field measurement be used to infer bulk aerosol properties and are conventional aerosol models adequate for radiation studies. The data from a polarimeter experiment were analyzed to show that the answers to both the questions are in the affirmative. The origin of a non-uniqueness inherent and generic to such remote radiation field measurements was identified and the implications are explained. An inadequacy that exists in the area of IR radiation transfer through a cloudless atmosphere was identified. This pertains to the failure of the Curtis-Godson (C-G) approximation in dealing with the 9.6 micro meters ozone absorption. A new approximation is described which improves the C-G method while preserving its simplicity. Calculations confirming the validity of the new approximation are also provided. Physical interpretation of why the new approximation is successful is also provided.

  14. Impacts and the early environment and evolution of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    Melosh, H. J.; Vickery, A. M.; Tonks, W. B.

    The effects of 'giant' impacts (i.e., impacts by bodies roughly half the diameter of the primary) on the thermal state of a growing planetary embryo are discussed. If the cumulative spectrum of planetesimal sizes is close to a power law of slope -2, then most of the mass and energy added to a growing planet will be deposited by such 'giant' impacts. In this case a simple pattern of temperature vs radius may never develop, as the thermal state at any given era will depend on the time, velocity, and obliquity of the last large collision. Impacts during heavy bombardment probably resulted in some net atmospheric loss from the earth and Venus, but the effect would have been much more pronounced on Mars, consistent with its very thin atmosphere. Such impacts may fractionate a planet's volatile inventory by sweeping away atmospheric gases but leaving condensible phases (such as water) only slightly changed.

  15. Journal of the Atmospheric Sciences EARLY ONLINE RELEASE

    E-print Network

    Johnson, Richard H.

    and Richard H. Johnson Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 1 Corresponding author address: Dr. Michael D. Toy, Department of Atmospheric Science, Colorado State University-LaTeX): Toy_Johnson_AMS_04_2013.article.ver_sub_4.docx #12;2 Abstract1 2 A long-lived heavy precipitation area

  16. From trihydrogen interstellar ion to hydrogen-oxygen reaction networks in terrestrial middle atmosphere

    NASA Astrophysics Data System (ADS)

    Varandas, A. J. C.

    After a brief overview on the generalized Born-Oppenheimer approximation and global modelling of electronic manifolds, we focus on two case histories. In the first, we report an accurate double-sheet potential energy surface1 and ro-vibrational calculations1,2 for the H3+(3A') ion which is of relevance in interstellar and plasma chemistries. In the second, we examine odd-hydrogen systems with up to five oxygen atoms which play a crucial role in the chemistry of the middle atmosphere. The premise will then be that all processes occur adiabatically on the relevant ground state potential energy surface, with the emphasis being on our recent observation that highly vibrationally excited spaecies such as O2(v) and OH (v) can hardly thermalize at such altitudes3, thus offering4 within this situation of local thermodynamic disequilibrium a possible clue for know mesospheric mysteries such as the ``ozone deficit problem'' and ``HOx dilemma''. We conclude with some remarks on continuing challenges and planned work.

  17. The terrestrial plant and herbivore arms race -- A major control of Phanerozoic atmospheric CO[sub 2

    SciTech Connect

    Olsen, P.E. (Columbia Univ., Palisades, NY (United States))

    1993-03-01

    Much recent work points to chemical weathering of continental silicates as the principal control of atmospheric CO[sub 2]. Presently, chemical weathering is mediated by plants. Vascular plants increase chemical weathering by drastically increasing acid leaching through respiration, decay, and microbial symbionts. Through the Phanerozoic the continuing evolution of terrestrial plant communities must have had a major effect on weathering rates. However, the efficacy of plant-induced-weathering is decreased by herbivory, which in turn decreases the invasion of soil by roots and leads to increased physical weathering. The author proposes that the major ice house--hot house cycles of the Devonian-Quaternary were caused by the lag between plant innovations and complete compensation by herbivore-detritivore response. In this way, it seems possible that: (1) the Carboniferous coals are a consequence of limited herbivory and soil litter decomposition and the Permo-Carboniferous glaciations were caused by dramatically increased chemical weathering caused by the previous global spread of vascular plants; (2) the Mesozoic hot house was brought on by massive increases in megaherbivores and litter decomposers; and (3) Cenozoic cooling and Quaternary glaciations resulted from the spread of herbaceous angiosperms and most recently grasslands. Earth's own superherbivory, if continued for tens of millions of years, will brings one back to mid-Mesozoic hot house conditions, not by the burning of fossil fuels, but rather by a global increase in physical over chemical weathering.

  18. Effect of the shrinking dipole on solar-terrestrial energy input to the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    McPherron, R. L.

    2011-12-01

    The global average temperature of the Earth is rising rapidly. This rise is primarily attributed to the release of greenhouse gases as a result of human activity. However, it has been argued that changes in radiation from the Sun might play a role. Most energy input to the Earth is light in the visible spectrum. Our best measurements suggest this power input has been constant for the last 40 years (the space age) apart from a small 11-year variation due to the solar cycle of sunspot activity. Another possible energy input from the Sun is the solar wind. The supersonic solar wind carries the magnetic field of the Sun into the solar system. As it passes the Earth it can connect to the Earth's magnetic field whenever it is antiparallel t the Earth's field. This connection allows mass, momentum, and energy from the solar wind to enter the magnetosphere producing geomagnetic activity. Ultimately much of this energy is deposited at high latitudes in the form of particle precipitation (aurora) and heating by electrical currents. Although the energy input by this process is miniscule compared to that from visible radiation it might alter the absorption of visible radiation. Two other processes affected by the solar cycle are atmospheric entry of galactic cosmic rays (GCR) and solar energetic protons (SEP). A weak solar magnetic field at sunspot minimum facilitates GCR entry which has been implicated in creation of clouds. Large coronal mass ejections and solar flares create SEP at solar maximum. All of these alternative energy inputs and their effects depend on the strength of the Earth's magnetic field. Currently the Earth's field is decreasing rapidly and conceivably might reverse polarity in 1000 years. In this paper we describe the changes in the Earth's magnetic field and how this might affect GCR, SEP, electrical heating, aurora, and radio propagation. Whether these effects are important in global climate change can only be determined by detailed physical models.

  19. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2

    PubMed Central

    Friend, Andrew D.; Lucht, Wolfgang; Rademacher, Tim T.; Keribin, Rozenn; Betts, Richard; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B.; Dankers, Rutger; Falloon, Pete D.; Ito, Akihiko; Kahana, Ron; Kleidon, Axel; Lomas, Mark R.; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Peylin, Philippe; Schaphoff, Sibyll; Vuichard, Nicolas; Warszawski, Lila; Wiltshire, Andy; Woodward, F. Ian

    2014-01-01

    Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models. For example, at 4 °C of global land surface warming (510–758 ppm of CO2), vegetation carbon increases by 52–477 Pg C (224 Pg C mean), mainly due to CO2 fertilization of photosynthesis. Simulations agree on large regional increases across much of the boreal forest, western Amazonia, central Africa, western China, and southeast Asia, with reductions across southwestern North America, central South America, southern Mediterranean areas, southwestern Africa, and southwestern Australia. Four vegetation models display discontinuities across 4 °C of warming, indicating global thresholds in the balance of positive and negative influences on productivity and biomass. In contrast to previous global vegetation model studies, we emphasize the importance of uncertainties in projected changes in carbon residence times. We find, when all seven models are considered for one representative concentration pathway × general circulation model combination, such uncertainties explain 30% more variation in modeled vegetation carbon change than responses of net primary productivity alone, increasing to 151% for non-HYBRID4 models. A change in research priorities away from production and toward structural dynamics and demographic processes is recommended. PMID:24344265

  20. Fossil wood and Mid-Eastern Europe terrestrial palaeobiogeography during the Jurassic–Early Cretaceous interval

    Microsoft Academic Search

    Marc Philippe; Maria Barbacka; Eugen Gradinaru; Eugenia Iamandei; Stãnilã Iamandei; Miklós Kázmér; Mihai Popa; György Szakmány; Platon Tchoumatchenco; Michal Zato?

    2006-01-01

    Palaeobiogeography plays an important role in the evolution of continental plants. This has been demonstrated mainly for modern biota and for past biota on a very large scale only. During the Jurassic–Early Cretaceous Mid-Eastern Europe was an archipelago, thus a particularly suitable area for a more detailed study. We investigated the area's plant palaeobiogeography, using fossil wood, with information from

  1. FUV Irradiances, Flares and Winds of the Early Sun: Effects on Early Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Guinan, E.

    We propose to use the FUSE satellite to determine the flare characteristics, winds, and accurate FUV irradiances for two solar-type stars that serve as proxies for the young Sun covering the first 300 Myr of its history. This program is the remaining part of a comprehensive study of the Sun in Time across the electromagnetic spectrum. We have defined a sample of single G0-5 V stars with well-known rotation periods and ages that are proxies for the Sun at different times. One of the major goals of the program was the determination of the spectral irradiance of the early Sun which is now nearing completion. Our analysis and modeling indicate that the strong XUV emissions of the young Sun could have played a crucial role in the developing planetary system, in particular through the photoionization, photochemical evolution and possible erosion of the planetary atmospheres. An important, yet still missing, ingredient to understand the early Sun is the characterization of the solar wind, flares and coronal mass ejections (CMEs). FUSE is uniquely suited to address these important question, both thanks to its high spectral resolution and wavelength coverage. The FUSE wavelength region contains key spectral features such as the H Lyman series, C III, O VI and an important coronal Fe XVIII line. Thus, FUSE observations permit the simultaneous study of plasmas covering temperatures from ~104 K to ~107 K. Enhancements of the hotter lines, line profile asymmetries or superimposed absorptions are the manifestations of winds, CMEs and flares. This program is also crucial for understanding the operation of the solar dynamo and the transfer of magnetic energy within the chromosphere, the transition region and the corona of the Sun and solar type stars.

  2. A Study of the Abundance and 13C/12C Ratio of Atmospheric Carbon Dioxide to Advance the Scientific Understanding of Terrestrial Processes Regulating the Global Carbon Cycle

    SciTech Connect

    Stephen C. Piper

    2005-10-15

    The primary goal of our research program, consistent with the goals of the U.S. Climate Change Science Program and funded by the terrestrial carbon processes (TCP) program of DOE, has been to improve understanding of changes in the distribution and cycling of carbon among the active land, ocean and atmosphere reservoirs, with particular emphasis on terrestrial ecosystems. Our approach is to systematically measure atmospheric CO2 to produce time series data essential to reveal temporal and spatial patterns. Additional measurements of the 13C/12C isotopic ratio of CO2 provide a basis for distinguishing organic and inorganic processes. To pursue the significance of these patterns further, our research also involved interpretations of the observations by models, measurements of inorganic carbon in sea water, and of CO2 in air near growing land plants.

  3. Climatic consequences of very high carbon dioxide levels in the earth's early atmosphere

    NASA Technical Reports Server (NTRS)

    Kasting, James F.; Ackerman, Thomas P.

    1986-01-01

    The possible consequences of very high carbon dioxide concentrations in the earth's early atmosphere have been investigated with a radiative-convective climate model. The early atmosphere would apparently have been stable against the onset of a runaway greenhouse (that is, the complete evaporation of the oceans) for carbon dioxide pressures up to at least 100 bars. A 10- to 20-bar carbon dioxide atmosphere, such as may have existed during the first several hundred million years of the earth's history, would have had a surface temperature of approximately 85 to 110 C. The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.

  4. Differentiating pedogenesis from diagenesis in early terrestrial paleoweathering surfaces formed on granitic composition parent materials

    USGS Publications Warehouse

    Driese, S.G.; Medaris, L.G., Jr.; Ren, M.; Runkel, A.C.; Langford, R.P.

    2007-01-01

    Unconformable surfaces separating Precambrian crystalline basement and overlying Proterozoic to Cambrian sedimentary rocks provide an exceptional opportunity to examine the role of primitive soil ecosystems in weathering and resultant formation of saprolite (weathered rock retaining rock structure) and regolith (weathered rock without rock structure), but many appear to have been affected by burial diagenesis and hydrothermal fluid flow, leading some researchers to discount their suitability for such studies. We examine one modern weathering profile (Cecil series), four Cambrian paleoweathering profiles from the North American craton (Squaw Creek, Franklin Mountains, Core SQ-8, and Core 4), one Neoproterozoic profile (Sheigra), and one late Paleoproterozoic profile (Baraboo), to test the hypothesis that these paleoweathering profiles do provide evidence of primitive terrestrial weathering despite their diagenetic and hydrothermal overprinting, especially additions of potassium. We employ an integrated approach using (1) detailed thin-section investigations to identify characteristic pedogenic features associated with saprolitization and formation of well-drained regoliths, (2) electron microprobe analysis to identify specific weathered and new mineral phases, and (3) geochemical mass balance techniques to characterize volume changes during weathering and elemental gains and losses of major and minor elements relative to the inferred parent materials. There is strong pedogenic evidence of paleoweathering, such as clay illuviation, sepic-plasmic fabrics, redoximorphic features, and dissolution and alteration of feldspars and mafic minerals to kaolinite, gibbsite, and Fe oxides, as well as geochemical evidence, such as whole-rock losses of Na, Ca, Mg, Si, Sr, Fe, and Mn greater than in modern profiles. Evidence of diagenesis includes net additions of K, Ba, and Rb determined through geochemical mass balance, K-feldspar overgrowths in overlying sandstone sections, and K-feldspars with reaction rims in weathered basement. The sub-Cambrian paleoweathering profiles formed on granite are remarkably similar to modern weathering profiles formed on granite, in spite of overprinting by potassium diagenesis. ?? 2007 by The University of Chicago. All rights reserved.

  5. Seasonal exchange of carbon dioxide between the atmosphere and the terrestrial biosphere: extrapolation from site-specific models to regional models

    SciTech Connect

    King, A.W.

    1986-01-01

    Ecological models of the seasonal exchange of carbon dioxide (CO/sub 2/) between the atmosphere and the terrestrial biosphere are needed in the study of changes in atmospheric CO/sub 2/ concentration. In response to this need, a set of site-specific models of seasonal terrestrial carbon dynamics was assembled from open-literature sources. The collection was chosen as a base for the development of biome-level models for each of the earth's principal terrestrial biomes or vegetation complexes. The primary disadvantage of this approach is the problem of extrapolating the site-specific models across large regions having considerable biotic, climatic, and edaphic heterogeneity. Two methods of extrapolation were tested. The first approach was a simple extrapolation that assumed relative within-biome homogeneity, and generated CO/sub 2/ source functions that differed dramatically from published estimates of CO/sub 2/ exchange. The second extrapolation explicitly incorporated within-biome variability in the abiotic variables that drive seasonal biosphere-atmosphere CO/sub 2/ exchange.

  6. Research Paper Haze Aerosols in the Atmosphere of Early Earth: Manna from Heaven

    Microsoft Academic Search

    ALEXANDER A. PAVLOV; DANIEL B. CURTIS; CHRISTOPHER P. MCKAY; DOUGLAS R. WORSNOP; ALICE E. DELIA; DARIN W. TOOHEY; OWEN B. TOON; MARGARET A. TOLBERT

    An organic haze layer in the upper atmosphere of Titan plays a crucial role in the atmospheric composition and climate of that moon. Such a haze layer may also have existed on the early Earth, providing an ultraviolet shield for greenhouse gases needed to warm the planet enough for life to arise and evolve. Despite the implications of such a

  7. Early public impressions of terrestrial carbon capture and storage in a coal-intensive state.

    PubMed

    Carley, Sanya R; Krause, Rachel M; Warren, David C; Rupp, John A; Graham, John D

    2012-07-01

    While carbon capture and storage (CCS) is considered to be critical to achieving long-term climate-protection goals, public concerns about the CCS practice could pose significant obstacles to its deployment. This study reports findings from the first state-wide survey of public perceptions of CCS in a coal-intensive state, with an analysis of which factors predict early attitudes toward CCS. Nearly three-quarters of an Indiana sample (N = 1001) agree that storing carbon underground is a good approach to protecting the environment, despite 80% of the sample being unaware of CCS prior to participation in the two-wave survey. The majority of respondents do not hold strong opinions about CCS technology. Multivariate analyses indicate that support for CCS is predicted by a belief that humankind contributes to climate change, a preference for increased use of renewable energy, and egalitarian and individualistic worldviews, while opposition to CCS is predicted by self-identified political conservatism and by selective attitudes regarding energy and climate change. Knowledge about early impressions of CCS can help inform near-term technology decisions at state regulatory agencies, utilities, and pipeline companies, but follow-up surveys are necessary to assess how public sentiments evolve in response to image-building efforts with different positions on coal and CCS. PMID:22681614

  8. Beyond the atmosphere: Early years of space science

    NASA Technical Reports Server (NTRS)

    Newell, H. E.

    1980-01-01

    From the rocket measurements of the upper atmosphere and Sun that began in 1946, space science gradually emerged as a new field of scientific activity. The course of the United State space program is viewed in an historical context. Major emphasis is on NASA and its programs. The funding, staffing, organization, and priorities of the space program were reviewed.

  9. Net terrestrial CO2 exchange over China during 2001-2010 estimated with an ensemble data assimilation system for atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Zhang, H. F.; Chen, B. Z.; Laan-Luijkx, I. T.; Chen, J.; Xu, G.; Yan, J. W.; Zhou, L. X.; Fukuyama, Y.; Tans, P. P.; Peters, W.

    2014-03-01

    In this paper we present an estimate of net ecosystem CO2 exchange over China for the years 2001-2010 using the CarbonTracker Data Assimilation System for CO2 (CTDAS). Additional Chinese and Asian CO2 observations are used in CTDAS to improve our estimate. We found that the combined terrestrial ecosystems in China absorbed about -0.33 Pg C yr-1 during 2001-2010. The uncertainty on Chinese terrestrial carbon exchange estimates as derived from a set of sensitivity experiments suggests a range of -0.29 to -0.64 Pg C yr-1. This total Chinese terrestrial CO2 sink is attributed to the three major biomes (forests, croplands, and grass/shrublands) with estimated CO2 fluxes of -0.12 Pg C yr-1 (range from -0.09 to -0.19 Pg C yr-1), -0.12 Pg C yr-1 (range from -0.09 to -0.26 Pg C yr-1), and -0.09 Pg C yr-1 (range from -0.09 to -0.17 Pg C yr-1), respectively. The peak-to-peak amplitude of interannual variability of the Chinese terrestrial ecosystem carbon flux is 0.21 Pg C yr-1 (~64% of mean annual average), with the smallest CO2 sink (-0.19 Pg C yr-1) in 2003 and the largest CO2 sink (-0.40 Pg C yr-1) in 2007. We stress that our estimate of terrestrial ecosystem CO2 uptake based on inverse modeling strongly depends on a limited number of atmospheric CO2 observations used. More observations in China specifically and in Asia in general are needed to improve the accuracy of terrestrial carbon budgeting for this region.

  10. Water loss from Venus: Implications for the Earth's early atmosphere

    NASA Technical Reports Server (NTRS)

    Richardson, S. M.; Pollack, J. B.; Reynolds, R. T.

    1985-01-01

    The atmosphere of Venus outgassed rapidly as a result of planetary heating during accretion, resulting in massive water loss. The processes affecting atmospheric chemistry following accretion have consisted largely of hydrogen escape and internal re-equilibrium. The initial bulk composition of Venus and Earth are assumed to have been roughly similar. Chemical speciation on Venus was controlled by the temperature and oxygen buffering capacity of the surface magma. It is also assumed that the surfaces of planetary bodies of the inner solar system were partly or wholly molten during accretion with a temperature estimated at 1273 to 1573 K. To investigate the range of reasonable initial atmospheric compositions on Venus, limits have to be set for the proportion of total hydrogen and the buffered fugacity of oxygen. Using the C/H ratio of 0.033 set for Earth, virtually all of the water generated during outgassing must later have been lost in order to bring the current CO2/H2O ratio for Venus up to its observed value of 10 sup 4 to 10 sup 5. The proportion of H2O decreases in model atmospheres with successfully higher C/H values, ultimately approaching the depleted values currently observed on Venus. Increasing C/H also results in a rapid increase in CO/H2O and provides an efficient mechanism for water loss by the reaction CO+H2O = CO2 + H2. This reaction, plus water loss mechanisms involving crustal iron, could have removed a very large volume of water from the Venusian atmosphere, even at a low C/H value.

  11. Early Cretaceous terrestrial ecosystems in East Asia based on food-web and energy-flow models

    USGS Publications Warehouse

    Matsukawa, M.; Saiki, K.; Ito, M.; Obata, I.; Nichols, D.J.; Lockley, M.G.; Kukihara, R.; Shibata, K.

    2006-01-01

    In recent years, there has been global interest in the environments and ecosystems around the world. It is helpful to reconstruct past environments and ecosystems to help understand them in the present and the future. The present environments and ecosystems are an evolving continuum with those of the past and the future. This paper demonstrates the contribution of geology and paleontology to such continua. Using fossils, we can make an estimation of past population density as an ecosystem index based on food-web and energy-flow models. Late Mesozoic nonmarine deposits are distributed widely on the eastern Asian continent and contain various kinds of fossils such as fishes, amphibians, reptiles, dinosaurs, mammals, bivalves, gastropods, insects, ostracodes, conchostracans, terrestrial plants, and others. These fossil organisms are useful for late Mesozoic terrestrial ecosystem reconstruction using food-web and energy-flow models. We chose Early Cretaceous fluvio-lacustrine basins in the Choyr area, southeastern Mongolia, and the Tetori area, Japan, for these analyses and as a potential model for reconstruction of other similar basins in East Asia. The food-web models are restored based on taxa that occurred in these basins. They form four or five trophic levels in an energy pyramid consisting of rich primary producers at its base and smaller biotas higher in the food web. This is the general energy pyramid of a typical ecosystem. Concerning the population densities of vertebrate taxa in 1 km2 in these basins, some differences are recognized between Early Cretaceous and the present. For example, Cretaceous estimates suggest 2.3 to 4.8 times as many herbivores and 26.0 to 105.5 times the carnivore population. These differences are useful for the evaluation of past population densities of vertebrate taxa. Such differences may also be caused by the different metabolism of different taxa. Preservation may also be a factor, and we recognize that various problems occur in past ecosystem reconstructions. Counts of small numbers of confirmed species and estimates of maximum numbers of species present in the basin are used for the analysis and estimation of energy flow. This approach applies the methods of modern ecosystem analysis. ?? 2005 Elsevier Ltd. All rights reserved.

  12. Constraints on early atmosphere from planetary accretion processes

    NASA Technical Reports Server (NTRS)

    Arrhenius, G.

    1985-01-01

    Evidence for composition and dynamics of release of the earliest volatiles was in lack of anything better being sought from the most ancient sediments known at the time, although they were recognized to be younger than three billion years. Origin of life on Earth was considered to require a lasting atmosphere with hydrogen and methane as major components. The new observations together with theoretical studies generated by the space program and by systematic exploration of the Earth's oceanic crust changed the climate of opinion in which the questions of the primordial atmosphere are discussed. Even though existing evidence does not permit conclusive choice of any specific scenario, the acceptance of specific model elements now forces the consideration of a series of consequences, some of which may be tested by observation.

  13. Contributions of icy planetesimals to the Earth's early atmosphere.

    PubMed

    Owen, T C; Bar-Nun, A

    2001-01-01

    Laboratory experiments on the trapping of gases by ice forming at low temperatures implicate comets as major carriers of the heavy noble gases to the inner planets. These icy planetesimals may also have brought the nitrogen compounds that ultimately produced atmospheric N2. However, if the sample of three comets analyzed so far is typical, the Earth's oceans cannot have been produced by comets alone, they require an additional source of water with low D/H. The highly fractionated neon in the Earth's atmosphere may also indicate the importance of non-icy carriers of volatiles. The most important additional carrier is probably the rocky material comprising the bulk of the mass of these planets. Venus may require a contribution from icy planetesimals formed at the low temperatures characteristic of the Kuiper Belt. PMID:11599179

  14. Evidence for weathering on early Mars from a comparison with terrestrial weathering profiles

    NASA Astrophysics Data System (ADS)

    Gaudin, A.; Dehouck, E.; Mangold, N.

    2011-11-01

    Phyllosilicates on Mars are widespread in the ancient crust suggesting the presence of liquid water at the martian surface and therefore warmer conditions during its early history. However, the role of the ancient climate in the alteration process, which produced these phyllosilicates, remains under debate, because similar mineral assemblages can be produced by hydrothermal alteration at depth. This paper focuses on the origin of coincident outcrops of Fe/Mg bearing phyllosilicates and Al-bearing phyllosilicates, which are observed in several regions of Mars. We performed a detailed mineralogical comparison between a section in Nili Fossae, Mars, and a weathering profile located at Murrin Murrin, Western Australia. The Murrin Murrin profile is developed in Archaean serpentinized peridotite massifs over a ˜40 m thick sequence. It has three alteration zones: the serpentine mineral saprolite is found at the bottom, immediately overlain by Fe/Mg-bearing smectites and then Al-bearing phyllosilicates (kaolinite) mixed with iron hydroxides. This example illustrates how Al-dominated minerals can derive from the alteration of initially Al-poor ultramafic rocks by the intense leaching of Mg 2+. This mineralogical sequence is very similar to that detected locally in Nili Fossae by orbital spectroscopy. By analogy, we propose that the mineral assemblage detected on Mars is the result of long-term weathering, and thus could be the best evidence of past weathering as a direct result of a climate significantly warmer than at present.

  15. Early hominin diet included diverse terrestrial and aquatic animals 1.95 Ma in East Turkana, Kenya

    PubMed Central

    Braun, David R.; Harris, John W. K.; Levin, Naomi E.; McCoy, Jack T.; Herries, Andy I. R.; Bamford, Marion K.; Bishop, Laura C.; Richmond, Brian G.; Kibunjia, Mzalendo

    2010-01-01

    The manufacture of stone tools and their use to access animal tissues by Pliocene hominins marks the origin of a key adaptation in human evolutionary history. Here we report an in situ archaeological assemblage from the Koobi Fora Formation in northern Kenya that provides a unique combination of faunal remains, some with direct evidence of butchery, and Oldowan artifacts, which are well dated to 1.95 Ma. This site provides the oldest in situ evidence that hominins, predating Homo erectus, enjoyed access to carcasses of terrestrial and aquatic animals that they butchered in a well-watered habitat. It also provides the earliest definitive evidence of the incorporation into the hominin diet of various aquatic animals including turtles, crocodiles, and fish, which are rich sources of specific nutrients needed in human brain growth. The evidence here shows that these critical brain-growth compounds were part of the diets of hominins before the appearance of Homo ergaster/erectus and could have played an important role in the evolution of larger brains in the early history of our lineage. PMID:20534571

  16. The role of terrestrial vegetation in atmospheric Hg deposition: Pools and fluxes of spike and ambient Hg from the METAALICUS experiment

    NASA Astrophysics Data System (ADS)

    Graydon, Jennifer A.; St. Louis, Vincent L.; Lindberg, Steve E.; Sandilands, Ken A.; Rudd, John W. M.; Kelly, Carol A.; Harris, Reed; Tate, Michael T.; Krabbenhoft, Dave P.; Emmerton, Craig A.; Asmath, Hamish; Richardson, Murray

    2012-03-01

    As part of the Mercury Experiment to Assess Atmospheric Loading in Canada and the U.S. (METAALICUS), different stable Hg(II) isotope spikes were applied to the upland and wetland areas of a boreal catchment between 2001 and 2006 to examine retention of newly deposited Hg(II). In the present study, a Geographical Information Systems (GIS)-based approach was used to quantify canopy and ground vegetation pools of experimentally applied upland and wetland spike Hg within the METAALICUS watershed over the terrestrial loading phase of the experiment. A chemical kinetic model was also used to describe the changes in spike Hg concentrations of canopy and ground vegetation over time. An examination of the fate of spike Hg initially present on canopy vegetation using a mass balance approach indicated that the largest percentage flux from the canopy over one year post-spray was emission to the atmosphere (upland: 45%; wetland: 71%), followed by litterfall (upland: 14%; wetland: 10%) and throughfall fluxes (upland: 12%; wetland: 9%) and longer term retention of spike in the forest canopy (11% for both upland and wetland). Average half-lives (t1/2) of spike on deciduous (110 ± 30 days) and coniferous (180 ± 40 days) canopy and ground vegetation (890 ± 620 days) indicated that retention of new atmospheric Hg(II) on terrestrial (especially ground) vegetation delays downward transport of new atmospheric Hg(II) into the soil profile and runoff into lakes.

  17. Stable hydrogen isotopic composition of n-alkanes in atmospheric aerosols as a tracer for the source region of terrestrial plant waxes

    NASA Astrophysics Data System (ADS)

    Yamamoto, S.; Kawamura, K.

    2009-12-01

    Studies on molecular composition and compound-specific carbon isotopic ratio (?13C) of leaf wax n-alkanes in atmospheric aerosols have revealed a long-range atmospheric transport of terrestrial higher plant materials over the south Atlantic and western Pacific oceans. However, molecular and ?13C compositions of terrestrial plant waxes in the eastern part of the Asian continent are relatively constant reflecting C3-dominated vegetation, which makes it difficult to specify the source regions of plant materials in the atmospheric aerosols over the East Asia and northwest Pacific regions. Recent observation displays a large (>100‰) spatial variation in hydrogen isotopic composition (?D) of rainwater in East Asia. Because ?D values of terrestrial higher plants sensitively reflect those of precipitation waters, ?D of leaf waxes are expected to provide information on their source region. In this study, we measured the ?D of n-alkanes in atmospheric aerosols from Tokyo to better understand the origin of leaf wax n-alkanes in atmospheric aerosols. The ?D values of fossil fuel n-alkanes (C21 to C24) in Tokyo aerosols range from -65 to -94‰, which are in a range of those reported in marine crude oils. In contrast, the ?D of higher molecular weight (C29 and C31) n-alkanes (?DHMW) show much larger values by ~70‰ than those of fossil fuel n-alkanes. Their values were found to exhibit concomitant variations with carbon preference index (CPI), suggesting that the ?DHMW reflect the ?D of leaf wax n-alkanes with a variable contribution from fossil fuel n-alkanes. Nevertheless, good positive correlation (r = 0.89, p < 0.01) between the ?DHMW and CPI values enable us to remove the contribution of fossil fuels using a mass balance approach by assuming that CPI of fossil fuel is 1 and CPI of plant waxes is 5-15. Calculated n-alkane ?D values averaged from -170 to -185‰ for C29 and from -155 to -168‰ for C31. These values are consistent with those reported from growing leaves in Tokyo, which confirms the usefulness of the ?D of long chain n-alkanes as a tracer for the source region of terrestrial plant waxes in atmospheric aerosols.

  18. Integrated Estimates of Global Terrestrial Carbon Sequestration

    SciTech Connect

    Thomson, Allison M.; Izaurralde, R Cesar; Smith, Steven J.; Clarke, Leon E.

    2008-02-01

    Assessing the contribution of terrestrial carbon sequestration to international climate change mitigation requires integration across scientific and disciplinary boundaries. As part of a scenario analysis for the US Climate Change Technology Program, measurements and geographic data were used to develop terrestrial carbon sequestration estimates for agricultural soil carbon, reforestation and pasture management. These estimates were then applied in the MiniCAM integrated assessment model to evaluate mitigation strategies within policy and technology scenarios aimed at achieving atmospheric CO2 stabilization by 2100. Adoption of terrestrial sequestration practices is based on competition for land and economic markets for carbon. Terrestrial sequestration reach a peak combined rate of 0.5 to 0.7 Gt carbon yr-1 in mid-century with contributions from agricultural soil (0.21 Gt carbon yr-1), reforestation (0.31 Gt carbon yr-1) and pasture (0.15 Gt carbon yr-1). Sequestration rates vary over time period and with different technology and policy scenarios. The combined contribution of terrestrial sequestration over the next century ranges from 31 to 41 GtC. The contribution of terrestrial sequestration to mitigation is highest early in the century, reaching up to 20% of total carbon mitigation. This analysis provides insight into the behavior of terrestrial carbon mitigation options in the presence and absence of climate change mitigation policies.

  19. Terrestrial Planets: Comparative Planetology

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Papers were presented at the 47th Annual Meteoritical Society Meeting on the Comparative planetology of Terrestrial Planets. Subject matter explored concerning terrestrial planets includes: interrelationships among planets; plaentary evolution; planetary structure; planetary composition; planetary Atmospheres; noble gases in meteorites; and planetary magnetic fields.

  20. Comparative Climatology of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Mackwell, Stephen J.; Simon-Miller, Amy A.; Harder, Jerald W.; Bullock, Mark A.

    Public awareness of climate change on Earth is currently very high, promoting significant interest in atmospheric processes. We are fortunate to live in an era where it is possible to study the climates of many planets, including our own, using spacecraft and groundbased observations as well as advanced computational power that allows detailed modeling. Planetary atmospheric dynamics and structure are all governed by the same basic physics. Thus differences in the input variables (such as composition, internal structure, and solar radiation) among the known planets provide a broad suite of natural laboratory settings for gaining new understanding of these physical processes and their outcomes. Diverse planetary settings provide insightful comparisons to atmospheric processes and feedbacks on Earth, allowing a greater understanding of the driving forces and external influences on our own planetary climate. They also inform us in our search for habitable environments on planets orbiting distant stars, a topic that was a focus of Exoplanets, the preceding book in the University of Arizona Press Space Sciences Series. Quite naturally, and perhaps inevitably, our fascination with climate is largely driven toward investigating the interplay between the early development of life and the presence of a suitable planetary climate. Our understanding of how habitable planets come to be begins with the worlds closest to home. Venus, Earth, and Mars differ only modestly in their mass and distance from the Sun, yet their current climates could scarcely be more divergent. Our purpose for this book is to set forth the foundations for this emerging science and to bring to the forefront our current understanding of atmospheric formation and climate evolution. Although there is significant comparison to be made to atmospheric processes on nonterrestrial planets in our solar system — the gas and ice giants — here we focus on the terrestrial planets, leaving even broader comparisons to a future volume. Our authors have taken on the task to look at climate on the terrestrial planets in the broadest sense possible — by comparing the atmospheric processes at work on the four terrestrial bodies, Earth, Venus, Mars, and Titan (Titan is included because it hosts many of the common processes), and on terrestrial planets around other stars. These processes include the interactions of shortwave and thermal radiation with the atmosphere, condensation and vaporization of volatiles, atmospheric dynamics, chemistry and aerosol formation, and the role of the surface and interior in the long-term evolution of climate. Chapters herein compare the scientific questions, analysis methods, numerical models, and spacecraft remote sensing experiments of Earth and the other terrestrial planets, emphasizing the underlying commonality of physical processes. We look to the future by identifying objectives for ongoing research and new missions. Through these pages we challenge practicing planetary scientists, and most importantly new students of any age, to find pathways and synergies for advancing the field. In Part I, Foundations, we introduce the fundamental physics of climate on terrestrial planets. Starting with the best studied planet by far, Earth, the first chapters discuss what is known and what is not known about the atmospheres and climates of the terrestrial planets of the solar system and beyond. In Part II, Greenhouse Effect and Atmospheric Dynamics, we focus on the processes that govern atmospheric motion and the role that general circulation models play in our current understanding. In Part III, Clouds and Hazes, we provide an in-depth look at the many effects of clouds and aerosols on planetary climate. Although this is a vigorous area of research in the Earth sciences, and very strongly influences climate modeling, the important role that aerosols and clouds play in the climate of all planets is not yet well constrained. This section is intended to stimulate further research on this critical subject. The study of climate involves much more than

  1. Early MAVEN Results on the Mars Upper Atmosphere and Atmospheric Loss to Space

    NASA Astrophysics Data System (ADS)

    Jakosky, Bruce; Grebowsky, Joe; Luhmann, Janet

    2015-04-01

    The Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft went into orbit around Mars on 21 September 2014. After a commissioning phase that included science observations of Mars and of Comet Siding Spring during its close approach, its primary science phase began on 16 November 2014 and will run for a full Earth year, until November 2015.The science objectives of the MAVEN mission are to characterize the upper atmosphere and ionospheric structure and composition, the interactions of the sun and the solar wind with the planet, and the processes driving loss of gas from the atmosphere to space. Our goal is to understand the chain of processes leading to escape today, learn how to extrapolate back in time, and determine the integrated escape of atmosphere over Martian history.MAVEN has nine instrument sensors collected into eight separate instruments. The first group of instruments measures the properties of the solar wind and of the sun that drive the processes in the upper atmosphere. The second group measures the structure and composition of the upper atmosphere and of the ions in the ionosphere, and also measures isotope ratios that can tell us about the integrated escape to space. In this group, NGIMS measures properties in situ at the location of the spacecraft, and IUVS measures them remotely, providing a powerful combination of local and global measurements. The third group measures the properties of the ionosphere that both drive escape and determine the composition and properties of the escaping ions.The spacecraft and all science instruments are functioning nominally, and science data is being collected utilizing our planned observing scenarios. The first deep-dip campaign is scheduled for the second week of February 2015.By the time of the TESS meeting, we expect to have a preliminary understanding of the instrument behavior, operations, and calibrations. We also expect to have sufficient data collected to allow us to reach preliminary conclusions about the state of the upper atmosphere, interactions with the solar wind, escape of atmospheric gas to space at the present epoch, and integrated escape to space over time.

  2. Seasonal exchange of carbon dioxide between the atmosphere and the terrestrial biosphere: extrapolation from site-specific models to regional models

    SciTech Connect

    King, A.W.

    1986-01-01

    Ecological models of the seasonal exchange of carbon dioxide between the atmosphere and the terrestrial biosphere are needed in the study of changes in atmospheric CO/sub 2/ concentration. In response to this need, a set of site-specific models of seasonal terrestrial carbon dynamics was assembled from open-literature sources. The collection was chosen as a base for the development of biome-level models for each of the earth's principal terrestrial biomes or vegetation complexes. Two methods of extrapolation were tested. The first approach was a simple extrapolation that assumed relative within-biome homogeneity, and generated CO/sub 2/ source functions that differed dramatically from published estimates of CO/sub 2/ exchange. The differences were so great that the simple extrapolation was rejected as a means of incorporating site-specific models in a global CO/sub 2/ source function. The second extrapolation explicitly incorporated within-biome variability in the abiotic variables that drive seasonal biosphere-atmosphere CO/sub 2/ exchange. Simulated site-specific CO/sub 2/ dynamics were treated as a function of multiple random variables. The predicated regional CO/sub 2/ exchange is the computed expected value of simulated site-specific exchanges for that region times the area of the region. The test involved the regional extrapolation of tundra and a coniferous forest carbon exchange model. Comparisons between the CO/sub 2/ exchange estimated by extrapolation and published estimates of regional exchange for the latitude belt support the appropriateness of extrapolation by expected value.

  3. Climatic effects of enhanced CO2 levels in Mars early atmosphere

    NASA Technical Reports Server (NTRS)

    Kasting, James F.

    1987-01-01

    Results are presented of one-dimensional radiation convection modeling of the early Mars atmosphere. Up to 5 bars of CO2 would have been required to raise the surface temperature (orbitally and globally averaged) above the freezing point, although at the equator at perihelion, 1 bar would have sufficed. Such an atmospheric CO2 invertory, the author argued, is not inconsistent with any known constraint on Mars' degassed volatile inventory.

  4. TERENO ("Terrestrial Environmental Observatories"): Establishment and Upgrading of a Terrestrial Observatory "Alpine upland" for Long Term Observations of the Impact of Global Change Factors on Biosphere-Hydrosphere-Atmosphere Interactions

    NASA Astrophysics Data System (ADS)

    Kunstmann, H.; Papen, H.; Butterbach-Bahl, K.; Kiese, R.; Marx, A.; Schmid, H.

    2007-12-01

    Long term observations are an indispensable pre-requisite to improve our knowledge of the complex biosphere- hydrosphere-atmosphere (BHA)-interactions and to detect and analyze the impact of Global Change parameters on these interactions as well as to develop, improve and validate BHA model systems. As an integral part of the Helmholtz initiative TERENO to establish/upgrade and equip terrestrial observatories for long term observations (> 10 years) on the effects of Global Change on complex terrestrial ecosystems, an observatory "Alpine Upland", operated jointly by the research centers FZK (Forschungszentrum Karlsruhe) and GSF (National Research Center for Environment and Health) is established. The central objectives of the scientific work performed by Forschungszentrum Karlsruhe within this observatory are: Characterization and quantification of changes of the (a) coupled C-/N-cycles and C-/N-storage (b)biosphere-atmosphere exchange (trace gases/energy flux/albedo) (c)vegetation and microbial biodiversity and of the temporal dynamics of matter- turnover and -exchange coupled to this change in biodiversity (d)terrestrial hydrology (alpine water budget, precipitation variability, extreme hydrometeorological events, seapage water quality/quantity, water retention capacity) in important climate- and use-sensitive ecosystem types within the pre-alpine region (e.g. alpine meadows, forests) under changing conditions of climate, management and nutrient deposition (atmospheric N-input). Besides upgrading of the already existing long term observation stations in the pre-alpine region ("The Höglwald Forest" (FZK) and the agricultural long term observation station "Scheyern" (for details see separate contribution of GSF) FZK will establish a "Climate-Feedback Observatory" at which the effects of predicted future changes in temperature and precipitation amount/distribution within the pre-alpine region on the complex BHA interactions will be studied applying a long term in-situ simulation experiment. For this a lysimeter network will be realized in which soil monoliths are transplanted along the existing natural gradient in temperature and precipitation within the alpine region. Details of this experimental approach will be presented.

  5. How are terrestrial gamma ray flashes produced in thunderstorms?

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-10-01

    Terrestrial gamma ray flashes (TGFs) are intense bursts of gamma rays that originate in thunderstorms and last from a few tens of microseconds to a few milliseconds. First observed in the early 1990s, TGFs are the highest-energy natural phenomenon originating within Earth's atmosphere.

  6. EFFECTS OF ELEVATED ATMOSPHERIC CO2 ON INVASIVE WEED SPECIES IN MANAGED TERRESTRIAL ECOSYSTEMS OF THE SOUTHEASTERN U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive weeds are estimated to cost U.S. agricultural and forest producers 34 billion dollars each year from decreased productivity and weed control efforts. Invasive plant pests, via their competitive aggression and absence of natural controls, have the ability to disrupt terrestrial ecosystems a...

  7. An upper limit on Early Mars atmospheric pressure from small ancient craters

    NASA Astrophysics Data System (ADS)

    Kite, E. S.; Williams, J.; Lucas, A.; Aharonson, O.

    2012-12-01

    Planetary atmospheres brake, ablate, and disrupt small asteroids and comets, filtering out small hypervelocity surface impacts and causing fireballs, airblasts, meteors, and meteorites. Hypervelocity craters <1 km diameter on Earth are typically caused by irons (because stones are more likely to break up), and the smallest hypervelocity craters near sea-level on Earth are ~20 m in diameter. 'Zap pits' as small as 30 microns are known from the airless moon, but the other airy worlds show the effects of progressively thicker atmospheres:- the modern Mars atmosphere is marginally capable of removing >90% of the kinetic energy of >240 kg iron impactors; Titan's paucity of small craters is consistent with a model predicting atmospheric filtering of craters smaller than 6-8km; and on Venus, craters below ~20 km diameter are substantially depleted. Changes in atmospheric CO2 concentration are believed to be the single most important control on Mars climate evolution and habitability. Existing data requires an early epoch of massive atmospheric loss to space; suggests that the present-day rate of escape to space is small; and offers only limited evidence for carbonate formation. Existing evidence has not led to convergence of atmosphere-evolution models, which must balance poorly understood fluxes from volcanic degassing, surface weathering, and escape to space. More direct measurements are required in order to determine the history of CO2 concentrations. Wind erosion and tectonics exposes ancient surfaces on Mars, and the size-frequency distribution of impacts on these surfaces has been previously suggested as a proxy time series of Mars atmospheric thickness. We will present a new upper limit on Early Mars atmospheric pressure using the size-frequency distribution of 20-100m diameter ancient craters in Aeolis Dorsa, validated using HiRISE DTMs, in combination with Monte Carlo simulations of the effect of paleo-atmospheres of varying thickness on the crater flux. These craters are interbedded with river deposits, and so the atmospheric state they record corresponds to an era when Mars was substantially wetter than the present, probably >3.7 Ga. An important caveat is that our technique cannot exclude atmospheric collapse-reinflation cycles on timescales much shorter than the sedimentary basin-filling time, so it sets an upper limit on the density of a thick stable paleoatmosphere. We will discuss our results in relation to previous estimates of ancient atmospheric pressure, and place new constraints on models of Early Mars climate.

  8. Ecological research in the large-scale biosphere-atmosphere experiment in Amazonia: early results

    Microsoft Academic Search

    Michael Keller; Ane Alencar; Gregory P. Asner; Bobby Braswell; Mercedes Bustamante; Eric Davidson; Ted Feldpausch; Erick Fernandes; Michael Goulden; Pavel Kabat; Bart Kruijt; F. Luizão; Scott Miller; Daniel Markewitz; Antonio D. Nobre; Carlos A. Nobre; Nicolau Priante Filho; Humberto da Rocha; Pedro Silva Dias; Celso von Randow; George L. Vourlitis

    2004-01-01

    The Large-scale Biosphere-Atmosphere Experiment in Amazonia (LBA) is a multinational, interdisciplinary research program led by Brazil. Ecological studies in LBA focus on how tropical forest conversion, regrowth, and selective logging influence carbon storage, nutrient dynamics, trace gas fluxes, and the prospect for sustainable land use in the Amazon region. Early results from ecological studies within LBA emphasize the var- iability

  9. Study of the Role of Terrestrial Processes in the Carbon Cycle Based on Measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    SciTech Connect

    Piper, Stephen C; Keeling, Ralph F

    2012-01-03

    The main objective of this project was to continue research to develop carbon cycle relationships related to the land biosphere based on remote measurements of atmospheric CO2 concentration and its isotopic ratios 13C/12C, 18O/16O, and 14C/12C. The project continued time-series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites. Using models of varying complexity, the concentration and isotopic measurements were used to study long-term change in the interhemispheric gradients in CO2 and 13C/12C to assess the magnitude and evolution of the northern terrestrial carbon sink, to study the increase in amplitude of the seasonal cycle of CO2, to use isotopic data to refine constraints on large scale changes in isotopic fractionation which may be related to changes in stomatal conductance, and to motivate improvements in terrestrial carbon cycle models. The original proposal called for a continuation of the new time series of 14C measurements but subsequent descoping to meet budgetary constraints required termination of measurements in 2007.

  10. Sensitivity of Holocene atmospheric CO2 and the modern carbon budget to early human land use: analyses with a process-based model

    NASA Astrophysics Data System (ADS)

    Stocker, B. D.; Strassmann, K.; Joos, F.

    2011-01-01

    A Dynamic Global Vegetation model coupled to a simplified Earth system model is used to simulate the impact of anthropogenic land cover changes (ALCC) on Holocene atmospheric CO2 and the contemporary carbon cycle. The model results suggest that early agricultural activities cannot explain the mid to late Holocene CO2 rise of 20 ppm measured on ice cores and that proposed upward revisions of Holocene ALCC imply a smaller contemporary terrestrial carbon sink. A set of illustrative scenarios is applied to test the robustness of these conclusions and to address the large discrepancies between published ALCC reconstructions. Simulated changes in atmospheric CO2 due to ALCC are less than 1 ppm before 1000 AD and 30 ppm at 2004 AD when the HYDE 3.1 ALCC reconstruction is prescribed for the past 12 000 years. Cumulative emissions of 69 GtC at 1850 and 233 GtC at 2004 AD are comparable to earlier estimates. CO2 changes due to ALCC exceed the simulated natural interannual variability only after 1000 AD. To consider evidence that land area used per person was higher before than during early industrialisation, agricultural areas from HYDE 3.1 were increased by a factor of two prior to 1700 AD (scenario H2). For the H2 scenario, the contemporary terrestrial carbon sink required to close the atmospheric CO2 budget is reduced by 0.5 GtC yr-1. Simulated CO2 remains small even in scenarios where average land use per person is increased beyond the range of published estimates. Even extreme assumptions for preindustrial land conversion and high per-capita land use do not result in simulated CO2 emissions that are sufficient to explain the magnitude and the timing of the late Holocene CO2 increase.

  11. Constraints on early Mars atmospheric pressure inferred from small ancient craters

    E-print Network

    Kite, Edwin S; Lucas, Antoine; Aharonson, Oded

    2013-01-01

    The single most important control on long-term climate change on Mars is thought to be decay of the CO2-dominated atmosphere, but direct constraints on paleoatmospheric pressure P are lacking. Of particular interest is the climate that allowed rivers to flow early in Mars history, which was affected by P via direct and indirect greenhouse effects. The size of craters embedded within ancient layered sediments is a proxy for P: the smaller the minimum-sized craters that form, the thinner the past atmosphere. Here we use high-resolution orthophotos and Digital Terrain Models (DTMs) to identify ancient craters among the river deposits of Aeolis, and compare their sizes to models of atmospheric filtering of impactors by thicker atmospheres. The best fit is P craters, so these fits are upper limits. Our work assumes target properties appropriate for desert alluvium: if sediment developed ...

  12. Complex Propagation of Large Sound Sources in Terrestrial-like Atmospheres and its Application to Bolide Detection

    Microsoft Academic Search

    Jean-pierre Williams; I. McEwan

    2006-01-01

    We have developed an advanced generalized, acoustic ray-tracing model to capture the behavior of sound (i.e. its radiation pattern and range of detectability) in the complex dynamical systems of the Venus, Earth, Mars, and Titan atmospheres. Sound propagation is affected by the composition, structure, and dynamics of a planet's atmosphere; therefore we have adopted a modular approach so that any

  13. Shock-induced CO2 loss from CaCO3: Implications for early planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1984-01-01

    Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes, which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesicular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

  14. Fair weather atmospheric electricity

    NASA Astrophysics Data System (ADS)

    Harrison, R. G.

    2011-06-01

    Not long after Franklin's iconic studies, an atmospheric electric field was discovered in "fair weather" regions, well away from thunderstorms. The origin of the fair weather field was sought by Lord Kelvin, through development of electrostatic instrumentation and early data logging techniques, but was ultimately explained through the global circuit model of C.T.R. Wilson. In Wilson's model, charge exchanged by disturbed weather electrifies the ionosphere, and returns via a small vertical current density in fair weather regions. New insights into the relevance of fair weather atmospheric electricity to terrestrial and planetary atmospheres are now emerging. For example, there is a possible role of the global circuit current density in atmospheric processes, such as cloud formation. Beyond natural atmospheric processes, a novel practical application is the use of early atmospheric electrostatic investigations to provide quantitative information on past urban air pollution.

  15. Evolution of High Temperature Early Atmosphere Under the Interaction of H2O-CO2 Supercritical Fluid With Minerals

    Microsoft Academic Search

    H. Isobe; T. Tomita; K. Ikeda

    2004-01-01

    The evolution of atmosphere-lithosphere system of the early Earth is controlled by mutual interaction of high temperature atmosphere with rocks and minerals. It is assumed that the total pressure of the early atmosphere and the surface temperature above initial magma ocean are 26MPa (H2O 20MPa, CO2 6MPa) and 130-330° C, respectively. This composition, temperature and pressure are very close to

  16. Complex Spatiotemporal Responses of Global Terrestrial Primary Production to Climate Change and Increasing Atmospheric CO2 in the 21st Century

    PubMed Central

    Pan, Shufen; Tian, Hanqin; Dangal, Shree R. S.; Zhang, Chi; Yang, Jia; Tao, Bo; Ouyang, Zhiyun; Wang, Xiaoke; Lu, Chaoqun; Ren, Wei; Banger, Kamaljit; Yang, Qichun; Zhang, Bowen; Li, Xia

    2014-01-01

    Quantitative information on the response of global terrestrial net primary production (NPP) to climate change and increasing atmospheric CO2 is essential for climate change adaptation and mitigation in the 21st century. Using a process-based ecosystem model (the Dynamic Land Ecosystem Model, DLEM), we quantified the magnitude and spatiotemporal variations of contemporary (2000s) global NPP, and projected its potential responses to climate and CO2 changes in the 21st century under the Special Report on Emission Scenarios (SRES) A2 and B1 of Intergovernmental Panel on Climate Change (IPCC). We estimated a global terrestrial NPP of 54.6 (52.8–56.4) PgC yr?1 as a result of multiple factors during 2000–2009. Climate change would either reduce global NPP (4.6%) under the A2 scenario or slightly enhance NPP (2.2%) under the B1 scenario during 2010–2099. In response to climate change, global NPP would first increase until surface air temperature increases by 1.5°C (until the 2030s) and then level-off or decline after it increases by more than 1.5°C (after the 2030s). This result supports the Copenhagen Accord Acknowledgement, which states that staying below 2°C may not be sufficient and the need to potentially aim for staying below 1.5°C. The CO2 fertilization effect would result in a 12%–13.9% increase in global NPP during the 21st century. The relative CO2 fertilization effect, i.e. change in NPP on per CO2 (ppm) bases, is projected to first increase quickly then level off in the 2070s and even decline by the end of the 2080s, possibly due to CO2 saturation and nutrient limitation. Terrestrial NPP responses to climate change and elevated atmospheric CO2 largely varied among biomes, with the largest increases in the tundra and boreal needleleaf deciduous forest. Compared to the low emission scenario (B1), the high emission scenario (A2) would lead to larger spatiotemporal variations in NPP, and more dramatic and counteracting impacts from climate and increasing atmospheric CO2. PMID:25401492

  17. Synthesis of nitrous oxide by lightning in the early anoxic Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Navarro, K. F.; Navarro-Gonzalez, R.; McKay, C. P.

    2013-12-01

    Carbon dioxide (CO2) was the main atmospheric component of the early Earth's atmosphere and exerted a key role in climate by maintaining a hydrosphere during a primitive faint Sun [1]; however, CO2 was eventually removed from the atmosphere by rock weathering and sequestered in the Earth's crust and mantle [1]. Nitric oxide (NO) was fixed by lightning discharges at a rate of 1×1016 molecules J-1 in CO2 (50-80%) rich atmospheres [2]. As the levels of atmospheric CO2 dropped to 20%, the production rate of NO by lightning rapidly decreased to 2×1014 molecules J-1 and then slowly diminished to 1×1014 molecules J-1 at CO2 levels of about 2.5% [2]. In order to maintain the existence of liquid water in the early Earth, it is required to warm up the planet with other greenhouse gases such as methane (CH4) [3]. Here we report an experimental study of the effects of lightning discharges on the nitrogen fixation rate during the evolution of the Earth's early atmosphere from 10 to 0.8 percent of carbon dioxide with methane concentrations from 0 to 1,000 ppm in molecular nitrogen. Lightning was simulated in the laboratory by a plasma generated with a pulsed Nd-YAG laser [2]. Our results show that the production of NO by lightning is independent of the presence of methane but drops from 3×1014 molecules J-1 in 10% CO2 to 5×1013 molecules J-1 in 1% CO2. Surprisingly, nitrous oxide (N2O) is also produced at a rate of 4×1013 molecules J-1 independent of the levels of CH4 and CO2. N2O is produced by lightning in the contemporaneous oxygenated Earth's atmosphere at a comparable rate of (0.4-1.5)×1013 molecules J-1 [4, 5], but was not detected in nitrogen-carbon dioxide mixtures in the absence of oxygen [6]. The only previously reported abiotic synthesis of N2O was by corona discharges in rich CO2 atmospheres (20-80%) with a production rate of 8×1012 molecules J-1 [6]; however at lower CO2 (<20%) levels, N2O is no longer produced. Therefore, lightning in the early Earth's atmosphere was the main source of N2O in nitrogen dominated atmospheres. N2O is not known to have played a role in abiotic synthesis. It is not incorporated by microorganisms, and hence may not have had a role in the supply of reactive nitrogen to the biosphere. However, it is a powerful greenhouse gas and may have had a role in warming up the early Earth's atmosphere [7]. Lightning activity is enhanced in a warmer climate [8] and so the production of N2O by lightning may have had a positive feedback in increasing lightning activity resulting in more N2O production. N2O is also produced by microbial activity and has been suggested as a potential biosignature in the atmospheres of extrasolar planets [9]. Here we show that lightning can interfere with the remote detection of life using N2O as a biosignature. [1] Kasting, J.F.: 1993, Science 259, 920; [2] Navarro-González, R., et al.: 2001, Nature 412, 61; [3] Tian, F., et al.: 2011, Earth Planet. Sci. Lett. 308, 417; [4] Levine, J.S. et al.: 1979, Geophys. Res. Lett. 6, 557; [5] [5] Hill, R.D. et al.: 1984, J. Geophys. Res. 89, 1411; [6] Nna Mvondo, D. et al.,: 2005, Origins Life Evol. Biosph. 35, 401; [7] Roberson, A.L. et al., Geobiology 9, 313; [8] Williams, E.R.: 2004, Atmos. Res. 76, 272; and [9] Rauer, H.S. et al., Astron. Astrophys. 529, A8.

  18. Two high resolution terrestrial records of atmospheric Pb deposition from New Brunswick, Canada, and Loch Laxford, Scotland

    Microsoft Academic Search

    Malin E. Kylander; Domink J. Weiss; Bernd Kober

    2009-01-01

    Environmental archives like peat deposits allow for the reconstruction of both naturally and anthropogenically forced changes in the biogeochemical cycle of Pb as well as the quantification of past and present atmospheric Pb pollution. However, records of atmospheric Pb deposition from pre-industrial times are lacking.In a publication by Weiss et al. [Weiss, D., Shotyk, W., Boyle, E.A., Kramers, J.D., Appleby,

  19. Evidence for ancient atmospheric xenon in Archean rocks and implications for the early evolution of the atmosphere

    NASA Astrophysics Data System (ADS)

    Pujol, M.; Marty, B.; Burnard, P.; Hofmann, A.

    2012-12-01

    The initial atmospheric xenon isotopic composition has been much debated over the last 4 decades. A Non radiogenic Earth Atmospheric xenon (NEA-Xe) composition has been proposed to be the best estimate of the initial signature ([1]). NEA-Xe consists of modern atmospheric Xe without fission (131-136Xe) or radioactive decay (129Xe) products. However, the isotope composition of such non-radiogenic xenon is very different to that of potential cosmochemical precursors such as solar or meteoritic Xe, as it is mass-fractionated by up to 3-4 % per amu relative to the potential precursors, and it is also elementally depleted relative to other noble gases. Because the Xe isotopic composition of the Archean appears to be intermediate between that of these cosmochemical end-members and that of the modern atmosphere, we argued that isotopic fractionation of atmospheric xenon did not occur early in Earth's history by hydrodynamic escape, as postulated by all other models ([1], [2], [3]), but instead was a continuous, long term process that lasted during at least the Hadean and Archean eons. Taken at face value, the decrease of the Xe isotopic fractionation from 1.6-2.1 % amu-1 3.5 Ga ago ([4]) to 1 % amu-1 3.0 Ga ago (Ar-Ar age in fluid inclusions trapped in quartz from the same Dresser Formation, [5]) could reflect a secular variation of the atmospheric Xe signature. Nevertheless, up until now, all data showing an isotopic mass fractionation have been measured in rocks and fluids from the same formation (Dresser Formation, Western Australia, aged 3.5 Ga), and have yet to be confirmed in rocks from different locations. In order to better constrain xenon isotopic fractionation of the atmosphere through time, we decided to analyze barites from different ages, geological environments and metamorphism grade. We started this study with barite from the Fig Tree Formation (South Africa, aged 3.26 Ga). This barite was sampled in old mines so have negligible modern exposure time. It is well preserved (no apparent metamorphism) and was deposited in a shallow submarine environment ("Finger type" barites) associated with hydrothermal circulation (white smokers). Compared to barite from the Dresser formation, Fig Tree barite had a long ancient exposure time in the subsurface (under shallow water for example) resulting in huge excesses of 131Xe (131Xe/130Xe ratio ~38 compared to 5.213 for the modern atmosphere one) due to 130Ba(n,?) reactions. Fissiogenic products (132 to 136Xe) are also more present than in barites from the Dresser Formation and are compatible with the age of the Fig Tree formation. Despite corrections for secondary productions that are hard to constrain, the Fig Tree barite still shows an isotopic mass fractionation of about 1% amu-1, consistent with our expected atmospheric fractionation evolution. [1] Pepin R. O. (1991) Icarus 92(1), 2-79. [2] Dauphas N. (2003) Icarus 165, 326-339. [3] Tolstikhin I. and O'Nions R.K. (1994) Chem. Geol. 115, 1-6. [4] Pujol M., Marty B., Burnard P. and Philippot P. (2009) Geochim. Cosmochim. Acta 73, 6834-46. [5] Pujol M., Marty B. and Burgess R. (2011) Earth Planet. Sci. Lett. 308, 298-306

  20. Atmospheric 14C variations derived from tree rings during the early Younger Dryas

    NASA Astrophysics Data System (ADS)

    Hua, Quan; Barbetti, Mike; Fink, David; Kaiser, Klaus Felix; Friedrich, Michael; Kromer, Bernd; Levchenko, Vladimir A.; Zoppi, Ugo; Smith, Andrew M.; Bertuch, Fiona

    2009-12-01

    Atmospheric radiocarbon variations over the Younger Dryas interval, from ˜13,000 to 11,600 cal yr BP, are of immense scientific interest because they reveal crucial information about the linkages between climate, ocean circulation and the carbon cycle. However, no direct and reliable atmospheric 14C records based on tree rings for the entire Younger Dryas have been available. In this paper, we present (1) high-precision 14C measurements on the extension of absolute tree-ring chronology from 12,400 to 12,560 cal yr BP and (2) high-precision, high-resolution atmospheric 14C record derived from a 617-yr-long tree-ring chronology of Huon pine from Tasmania, Australia, spanning the early Younger Dryas. The new tree-ring 14C records bridge the current gap in European tree-ring radiocarbon chronologies during the early Younger Dryas, linking the floating Lateglacial Pine record to the absolute tree-ring timescale. A continuous and reliable atmospheric 14C record for the past 14,000 cal yr BP including the Younger Dryas is now available. The new records indicate that the abrupt rise in atmospheric ? 14C associated with the Younger Dryas onset occurs at ˜12,760 cal yr BP, ˜240 yrs later than that recorded in Cariaco varves, with a smaller magnitude of ˜40‰ followed by several centennial ? 14C variations of 20-25‰. Comparing the tree-ring ? 14C to marine-derived ? 14C and modelled ? 14C based on ice-core 10Be fluxes, we conclude that changes in ocean circulation were mainly responsible for the Younger Dryas onset, while a combination of changes in ocean circulation and 14C production rate were responsible for atmospheric ? 14C variations for the remainder of the Younger Dryas.

  1. Isotopic and anatomical evidence of an herbivorous diet in the Early Tertiary giant bird Gastornis. Implications for the structure of Paleocene terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Angst, D.; Lécuyer, C.; Amiot, R.; Buffetaut, E.; Fourel, F.; Martineau, F.; Legendre, S.; Abourachid, A.; Herrel, A.

    2014-04-01

    The mode of life of the early Tertiary giant bird Gastornis has long been a matter of controversy. Although it has often been reconstructed as an apex predator feeding on small mammals, according to other interpretations, it was in fact a large herbivore. To determine the diet of this bird, we analyze here the carbon isotope composition of the bone apatite from Gastornis and contemporaneous herbivorous mammals. Based on 13C-enrichment measured between carbonate and diet of carnivorous and herbivorous modern birds, the carbonate ?13C values of Gastornis bone remains, recovered from four Paleocene and Eocene French localities, indicate that this bird fed on plants. This is confirmed by a morphofunctional study showing that the reconstructed jaw musculature of Gastornis was similar to that of living herbivorous birds and unlike that of carnivorous forms. The herbivorous Gastornis was the largest terrestrial tetrapod in the Paleocene biota of Europe, unlike the situation in North America and Asia, where Gastornis is first recorded in the early Eocene, and the largest Paleocene animals were herbivorous mammals. The structure of the Paleocene terrestrial ecosystems of Europe may have been similar to that of some large islands, notably Madagascar, prior to the arrival of humans.

  2. Mitigation of atmospheric effects on terrestrial FSO communication systems by using high-speed beam tracking antenna

    NASA Astrophysics Data System (ADS)

    Kazaura, Kamugisha; Omae, Kazunori; Suzuki, Toshiji; Matsumoto, Mitsuji; Sato, Takuro; Asatani, Koichi; Hatori, Mitsutoshi; Murakami, Tadaaki; Takahashi, Koichi; Matsumoto, Hideki; Wakamori, Kazuhiko; Arimoto, Yoshinori

    2006-02-01

    When a free-space optical beam propagates through the atmosphere it experiences deterioration and deformation of its wave-front caused from small scale, randomly localized changes in the atmospheric index of refraction. This results in beam wander and scintillation effects which can reduce the link availability and may introduce burst errors. This paper outlines experimental work on a free-space optical (FSO) communication system which connects an optical beam directly to a single-mode fiber (SMF) without any optical-to-electrical (O-E) conversion. In order to effectively couple the 1550 nm transmitted optical beam to a SMF it is necessary to be able to track and control the beam angle-of-arrival (AOA) changes. To achieve this, we have developed an optical antenna which uses a fine positioning mirror (FPM) capable of performing high-speed beam tracking and steering thus reducing to a great extent the optical power fluctuations of the received beam coupled to the SMF. This optical power fluctuation is partly a result of beam angle-of-arrival fluctuations caused by atmospheric turbulence. In our experiments we have tried to measure and quantify the magnitude of atmospheric turbulence experienced by an optical beam propagating through the atmosphere. First we demonstrate the relation between the AOA fluctuations and the frequency characteristics of the scintillation effects for a free-space optical beam propagating through a turbulent atmosphere. We use this information to determine the optimum antenna FPM tracking speed for improved performance and error free transmission. The results in the improved fiber received power as well as continuous error free transmission are presented.

  3. Studies of the airglow, the aurora, the ion and neutral composition, and the chemistry of the terrestrial atmosphere

    NASA Technical Reports Server (NTRS)

    Zipf, E. C., Jr.

    1974-01-01

    Results obtained by rocket-borne optical spectrometry are presented. Composition measurements and auroral studies are reported. The production of N (D-2) atoms by photo-absorption processes, and by electron impact excitation of N2 are discussed along with vibrationally excited CO2(+) ions in planetary atmospheres.

  4. ROLE OF LEAF SURFACE WATER IN THE BI-DIRECTIONAL AMMONIA EXCHANGE BETWEEN THE ATMOSPHERE AND TERRESTRIAL BIOSPHERE

    EPA Science Inventory

    A field experiment was conducted to study the ammonia exchange between plants and the atmosphere in a soybean field in Duplin County, North Carolina during the summer of 2002. Measurements indicate that the net canopy-scale ammonia exchange is bi-directional and has a significant...

  5. Effects of elevated atmospheric carbon dioxide on soil carbon in terrestrial ecosystems of the Southeastern U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants depend on carbon dioxide (CO2) as the substrate for photosynthesis; they remove CO2 from the atmosphere and use it for tissue production, respiring a portion back to the air. A portion of the carbon (C) fixed by plants enters the soil via root exudation and as plant litter (both aboveground ...

  6. Simulations of the Atmospheres of Synchronously Rotating Terrestrial Planets Orbiting M Dwarfs: Conditions for Atmospheric Collapse and the Implications for Habitability

    Microsoft Academic Search

    M. M. Joshi; R. M. Haberle; R. T. Reynolds

    1997-01-01

    Planets within the habitable zones of M dwarfs are likely to be synchronous rotators; in other words, one side is permanently illuminated while the other side is in perpetual darkness. We present results of three-dimensional simulations of the atmospheres of such planets, and comment on their possible habitability. Near the ground, a thermally direct longitudinal cell exists, transporting heat from

  7. Arctic Climate and Terrestrial Vegetation Responses During the Middle to Late Eocene and Early Oligocene: Colder Winters Preceded Cool-Down.

    NASA Astrophysics Data System (ADS)

    Greenwood, D. R.; Eldrett, J.

    2006-12-01

    The late Eocene to early Oligocene is recognized as an interval of substantial change in the global climate, with isotopic proxies of climate indicating a significant drop in sea surface temperatures. Other studies have shown, however that at middle latitudes that terrestrial mean annual temperature did not change significantly over this interval, and that the major change was likely a shift towards a greater range of seasonal temperatures; colder winters and warmer summers. Previous analyses of high latitude (Arctic) middle Eocene climate using both leaf physiognomic analysis and qualitative analysis of identified nearest living relatives of terrestrial floras indicated upper microthermal environments (mean annual temp. or MAT ca 10°C but perhaps as high as 15°C, coldest month mean temp. or CMMT ca 0°C) for Axel Heiberg Island in the Arctic Archipelago, but did not address precipitation nor provide data on the Eocene-Oligocene transition in the Arctic. Presented here are new estimates of temperature and precipitation (annual and season amounts) for the Arctic based on NLR analysis of terrestrial plant palynomorphs (spores and pollen) from the ODP 913B and 985 cores from near Greenland. The record of climate for the Greenland cores show a similar climate in the middle Eocene to that previously estimated for Axel Heiberg Island further to the west, with MAT 10- 15°C but with CMMT >5°C. Precipitation was high (mean annual precip. or MAP >180 cm/yr), although with large uncertainties attached to the estimate. The climate proxy record for the late Eocene to early Oligocene shows a lack of change in MAT and MAP over the time interval. Consistent with other published records at middle latitudes, however, winter temperatures (as CMMT) show greater variability leading up to the E-O boundary, and consistently cooler values in the early Oligocene (CMMT <5°C) than recorded for most of the middle to late Eocene record (CMMT >5°C). Plant groups sensitive to freezing such as palms and the floating water fern Azolla were present in the warm parts of the record, but are absent from the latest Eocene and early Oligocene record. These data provide further evidence that the primary change in the global climate system in the E-O transition was a shift towards more extreme seasonal temperature ranges, rather than a drop in the mean temperature.

  8. Investigating CO2 Reservoirs at Gale Crater and Evidence for a Dense Early Atmosphere

    NASA Technical Reports Server (NTRS)

    Niles, P. B.; Archer, P. D.; Heil, E.; Eigenbrode, J.; McAdam, A.; Sutter, B.; Franz, H.; Navarro-Gonzalez, R.; Ming, D.; Mahaffy, P. R.; Martin-Torres, F. J.; Zorzano, M.

    2015-01-01

    One of the most compelling features of the Gale landing site is its age. Based on crater counts, the formation of Gale crater is dated to be near the beginning of the Hesperian near the pivotal Hesperian/Noachian transition. This is a time period on Mars that is linked to increased fluvial activity through valley network formation and also marks a transition from higher erosion rates/clay mineral formation to lower erosion rates with mineralogies dominated by sulfate minerals. Results from the Curiosity mission have shown extensive evidence for fluvial activity within the crater suggesting that sediments on the floor of the crater and even sediments making up Mt. Sharp itself were the result of longstanding activity of liquid water. Warm/wet conditions on early Mars are likely due to a thicker atmosphere and increased abundance of greenhouse gases including the main component of the atmosphere, CO2. Carbon dioxide is minor component of the Earth's atmosphere yet plays a major role in surface water chemistry, weathering, and formation of secondary minerals. An ancient martian atmosphere was likely dominated by CO2 and any waters in equilibrium with this atmosphere would have different chemical characteristics. Studies have noted that high partial pressures of CO2 would result in increased carbonic acid formation and lowering of the pH so that carbonate minerals are not stable. However, if there were a dense CO2 atmosphere present at the Hesperian/Noachian transition, it would have to be stored in a carbon reservoir on the surface or lost to space. The Mt. Sharp sediments are potentially one of the best places on Mars to investigate these CO2 reservoirs as they are proposed to have formed in the early Hesperian, from an alkaline lake, and record the transition to an aeolian dominated regime near the top of the sequence. The total amount of CO2 in the Gale crater soils and sediments is significant but lower than expected if a thick atmosphere was present at the Hesperian/Noachian boundary. Likewise, the absence of carbonates suggests that CO2- weathering processes similar to those present on Earth were not dominant. Instead it is possible that more exotic CO2 deposition has occurred driven by atmospheric photochemistry and/or degradation of organic carbon.

  9. Methane fluxes between terrestrial ecosystems and the atmosphere at northern high latitudes during the past century: A retrospective analysis with a process-based biogeochemistry model

    USGS Publications Warehouse

    Zhuang, Q.; Melillo, J.M.; Kicklighter, D.W.; Prinn, R.G.; McGuire, A.D.; Steudler, P.A.; Felzer, B.S.; Hu, S.

    2004-01-01

    We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century in response to observed changes in the region's climate. We estimate that the net emissions of CH4 (emissions minus consumption) from these soils have increased by an average 0.08 Tg CH4 yr-1 during the twentieth century. Our estimate of the annual net emission rate at the end of the century for the region is 51 Tg CH4 yr-1. Russia, Canada, and Alaska are the major CH4 regional sources to the atmosphere, responsible for 64%, 11%, and 7% of these net emissions, respectively. Our simulations indicate that large interannual variability in net CH4 emissions occurred over the last century. Our analyses of the responses of net CH4 emissions to the past climate change suggest that future global warming will increase net CH4 emissions from the Pan-Arctic region. The higher net CH4 emissions may increase atmospheric CH 4 concentrations to provide a major positive feedback to the climate system. Copyright 2004 by the American Geophysical Union.

  10. The young sun, the early earth and the photochemistry of oxygen, ozone and formaldehyde in the early atmosphere

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Levine, J. S.; Augustsson, T. R.; Imhoff, C. L.; Goldman, I.; Hubickyj, O.

    1986-01-01

    Recent work on the evolution of the solar nebula and the subsequent formation of planets is reviewed, and the stages of star formation thought to lead to a protosun and an accompanying solar nebula are considered. Photochemical results suggest that concentrations of O2, O3, and H2CO, and the ratio of CO/CO2 in the prebiological paleoatmosphere are very sensitive to atmospheric levels of H2O and CO2 and to the flux of incident solar ultraviolet. For enhanced levels of CO2 and solar UV, surface levels of O2 may have approached the parts per billion level in the prebiological paleoatmosphere. It is suggested that 10 percent or more of the enhanced H2CO production could have been rained out of the atmosphere into the early oceans where synthesis into more complex organic molecules could have taken place. CO/CO2 values of greater than unity could have been possible for enhanced levels of solar UV flux.

  11. Diagnosing atmosphere-ocean general circulation model errors relevant to the terrestrial biosphere using the Köppen climate classification

    Microsoft Academic Search

    Anand Gnanadesikan; Ronald J. Stouffer

    2006-01-01

    Coupled atmosphere-ocean-land-sea ice climate models (AOGCMs) are often tuned using physical variables like temperature and precipitation with the goal of minimizing properties such as the root-mean-square error. As the community moves towards modeling the earth system, it is important to note that not all biases have equivalent impacts on biology. Bioclimatic classification systems provide means of filtering model errors so

  12. A process-level evaluation of the spatiotemporal variability of CO2 fluxes predicted by terrestrial biosphere models using atmospheric data

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Michalak, A. M.; Shiga, Y. P.; Yadav, V.

    2013-12-01

    Terrestrial biosphere models (TBMs) are used to extrapolate local observations and process-level understanding of land-atmosphere carbon exchange to larger regions, and can serve as a predictive tool for examining carbon-climate interactions and global change. Understanding and improving the performance of TBMs is thus crucial to the carbon cycle research community. In this work, we evaluate the spatiotemporal patterns of net ecosystem exchange (NEE) simulated by TBMs using atmospheric CO2 observations and a Geostatistical Inverse Modeling (GIM) framework. The evaluation methodology is based on the ability (or inability) of the spatiotemporal patterns in NEE estimates to explain the variability observed in atmospheric CO2 distribution. More simply, we examine whether the spatiotemporal patterns of NEE simulated by TBMs (including CASA-GFED, ORCHIDEE, VEGAS2 and SiB3) are consistent with the variations observed in the atmosphere. A similar GIM methodology is also applied using environmental variables (such as water availability, temperature, radiation, etc.) rather than TBMs, to explore the environmental processes associated with the variability of NEE, and determine which processes are associated with good/poor performance in TBMs. We find that NEE simulated by TBMs is consistent with that seen by atmospheric measurements more often during growing season months (Apr-Sept) than during the non-growing season. Over Temperate Broadleaf and Mixed Forests, Temperate Coniferous Forests and Temperate Grasslands, Savannas and Shrublands, atmospheric measurements are sufficiently sensitive to NEE fluxes to constrain the evaluation of model performance during the majority of the year (about 7-8 months in a year, mostly in growing season). For these regions and months, at least one of the TBMs is found to be able to reproduce the observed variability, but the most representative TBM varies by region and month. For the remaining months, none of the TBMs are able to reproduce the observed variability, whereas a linear combination of environmental variables is able to do so. By further comparing environmental processes associated with the spatiotemporal variability of NEE from the observations and from each TBM, we find that TBMs perform well when radiation-related processes are dominant; however, TBMs perform less well when water-availability (and temperature) are more important. It thus appears that the representation of water availability and its impact on fluxes within TBMs are areas of opportunity for improving TBM predictions, for example, in the seasonal transition. Further exploration of the processes associated with water availability in state-of-the-art TBMs, such as soil respiration, could therefore lead to improvements in their ability to represent the spatiotemporal variability of fluxes during the dormant season and their ability to represent phenology and carbon exchange during transition months.

  13. Recharge of the early atmosphere of Mars by impact-induced release of CO2

    NASA Technical Reports Server (NTRS)

    Carr, Michael H.

    1989-01-01

    The question as to whether high impact rates early in the history of Mars could have aided in maintaining a relatively thick CO2 atmosphere is discussed. Such impacts could have released CO2 into the atmosphere by burial, by shock-induced release during impact events, and by the addition of carbon to Mars from the impacting bolides. On the assumption that cratering rates on Mars were comparable to those of the moon's Nectarial period, burial rates are a result of 'impact gardening' at the end of heavy bombardment are estimated to have ranged from 20 to 45 m/million years; at these rates, 0.1-0.2 bar of CO2 would have been released every 10 million years as a result of burial to depths at which carbonate dissociation temperatures are encountered.

  14. Simulation of the capabilities of an orbiter for monitoring the entry of interplanetary matter into the terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Bouquet, Alexis; Baratoux, David; Vaubaillon, Jérémie; Gritsevich, Maria I.; Mimoun, David; Mousis, Olivier; Bouley, Sylvain

    2014-11-01

    In comparison with existing ground-based camera networks for meteors monitoring, a space-based optical system would escape dependency on weather and atmospheric conditions and would offer a wide spatial coverage and an unrestricted and extinction-free spectral domain. The potential rates of meteor detections by such systems are evaluated in this paper as a function of observations parameters (optical system capabilities, orbital parameters) and considering a reasonable range of meteoroids properties (e.g., mass, velocity, composition) determining their luminosity. A numerical tool called SWARMS (Simulator for Wide Area Recording of Meteors from Space) has been developed. SWARMS is also intended to be used in an operational phase to facilitate the comparison of observations with up-do-date constraints on the flux and characteristics of the interplanetary matter entering our planet's atmosphere. The laws governing the conversion of a fraction of the meteor kinetic energy into radiation during atmospheric entry have been revisited and evaluated based on an analysis of previously published meteor trajectories. Rates of detection were simulated for two different systems: the SPOSH (Smart Panoramic Optical Sensor Head) camera optimized for the observation of transient luminous events, and the JEM-EUSO (Japanese Experiment Module-Extreme Universe Space Observatory) experiment on the ISS (International Space Station). We conclude that up to 6 events per hour in the case of SPOSH, and up to 0.67 events in the case of JEM-EUSO may be detected. The optimal orbit for achieving such rates of detections depends on the mass index of the meteoroid populations. The determination of this parameter appears therefore critical before an optimal orbiting system might be designed for meteors monitoring.

  15. Wet surface and dense atmosphere on early Mars suggested by the bomb sag at Home Plate, Mars

    E-print Network

    Kite, Edwin

    Wet surface and dense atmosphere on early Mars suggested by the bomb sag at Home Plate, Mars Spirit observation of a bomb sag produced by an explosive volcanic eruption to infer the atmospheric) of bomb sags, 2) the morphology of the impact crater, and 3) the penetration depth of the clast

  16. Ideas and Perspectives: On the emission of amines from terrestrial vegetation in the context of atmospheric new particle formation

    NASA Astrophysics Data System (ADS)

    Sintermann, J.; Neftel, A.

    2015-02-01

    In this article we summarise recent science, which shows how airborne amines, specifically methylamines (MAs), play a key role in atmospheric new particle formation (NPF) by stabilising small molecule clusters. Agricultural emissions are assumed to constitute the most important MA source, but given the short atmospheric residence time of MAs, they can hardly have a direct impact on NFP events observed in remote regions. This leads us to the presentation of existing knowledge focussing on natural vegetation-related MA sources. High MA contents as well as emissions by plants have already been described in the 19th century. Strong MA emissions predominantly occur during flowering as part of a pollination strategy. The behaviour is species specific, but examples of such species are common and widespread. In addition, vegetative plant tissue exhibiting high amounts of MAs might potentially lead to significant emissions, and the decomposition of organic material could constitute another source for airborne MAs. These mechanisms would provide sources, which could be crucial for the amine's role in NPF, especially in remote regions. Knowledge about vegetation-related amine emissions is, however, very limited and thus it is also an open question how Global Change and the intensified cycling of reactive nitrogen over the last 200 years have altered amine emissions from vegetation with a corresponding effect on NPF.

  17. Turbulent atmospheric plumes above line sources with an application to volcanic fissure eruptions on the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

    The theory of turbulent plumes maintained above steady line sources of buoyancy is worked out in detail within the limitations of Taylor's entrainment assumption. It is applied to the structure of a pure plume injected into a stably stratified atmosphere. Volcanic basalt eruptions that develop from long, narrow vents create line source plumes, which rise well above the magmatic fire fountains playing near the ground level. The eruption of Laki in 1783 may provide an example of this style of eruption. Flood basalts are more ancient examples. Evidence of enormous fissure eruptions that occurred in the past on Mars and Venus also exists. Owing to the different properties of the atmospheres on these two planets from those on the earth, heights of line source plumes are expected to vary in the ratios 1:6:0.6 (earth:Mars:Venus). It is very unlikely that the observed increase of sulfur dioxide above the Venusian cloud deck in 1978 could have been due to a line source volcanic eruption, even if it had been a flood basalt eruption.

  18. Solar terrestrial observatory

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Eight basic solar-terrestrial scientific objectives that benefit from the Shuttle/Platform approach and a program of measurements for each are discussed. The objectives are to understand: (1) solar variability, (2) wave-particle processes, (3) magnetosphere-ionosphere mass transport, (4) the global electric circuit, (5) upper atmospheric dynamics, (6) middle atmospheric chemistry and energetics, (7) lower atmospheric turbidity, and (8) planetary atmospheric waves. A two stage approach to a multidisciplinary payload is developed: an initial STO, that uses a single platform in a low-Earth orbit, and an advanced STO that uses two platforms in differing orbits.

  19. GLOBAL TERRESTRIAL CARBON CYCLE

    EPA Science Inventory

    There is great uncertainty with regard to the future role of the terrestrial biosphere in the global carbon cycle, arising from both an inadequate understanding of current pools and fluxes as well as the potential effects of rising atmospheric concentrations of CO, on natural eco...

  20. The Terrestrial Planet Finder

    Microsoft Academic Search

    Peter R. Lawson

    2001-01-01

    The Terrestrial Planet Finder (TPF) is a space-based astronomical telescope that will combine high sensitivity and spatial resolution to detect and characterize ~150 planetary systems within 15 pc of our Sun. In a five-year mission, currently expected to commence in 2012, TPF will look for the atmospheric signatures of life using the methods of planetary spectroscopy. This is only possible

  1. A New Source Model of Non-Tidal Mass Variability in Atmosphere, Oceans, Terrestrial Hydrosphere, and the Solid Earth for Simulation Studies of Future Satellite Gravity Missions

    NASA Astrophysics Data System (ADS)

    Dobslaw, Henryk; Bergmann-Wolf, Inga; Dill, Robert; Klemann, Volker; Kusche, Jürgen; Sasgen, Ingo; Thomas, Maik

    2014-05-01

    The ability of any satellite gravity mission concept to monitor mass transport processes in the Earth system is typically tested well ahead of its implementation by means of various simulation studies. Those studies often extend from the simulation of realistic orbits and instrumental data all the way down to the retrieval of global gravity field solution time-series. Basic requirement for all these simulations are realistic representations of the spatio-temporal mass variability in the different sub-systems of the Earth, as a source model for the orbit computations and assess the performance of the gravity field retrieval. For such simulations, a suitable source model is required to represent (i) high-frequency (~ daily) redistribution, for example, in the atmosphere and oceans, in order to realistically include the effects of temporal aliasing due to non-tidal high-frequency mass variability into the retrieved gravity fields. In parallel, (ii) low-frequency (weekly to monthly) variability needs to be modelled with realistic amplitudes, particularly at small spatial scales, in order to assess to what extent a new mission concept might provide further insight into physical processes currently not observable. The new source model presented in this study attempts to fulfil both requirements: Based on ECMWF's recent atmospheric reanalysis ERA Interim and corresponding simulations from numerical models of the other Earth system components, it offers spherical harmonic (SH) coefficients of the mass variability in atmosphere, oceans, the terrestrial hydrosphere including the ice-sheets and glaciers,as well as the solid Earth. Simulated features range from high temporal (6 hours) to long-term (inter-annual) with a spatial resolution of SH degree and order 180, encompassing a a period of 12 years. Associated with the source model, a de-aliasing model for atmospheric and oceanic high-frequency variability is available with augmented errors for a more realistic description of the process of the gravity field retrieval. Several features of this new dataset will be highlighted in this presentation in order to provide guidance for its application in upcoming future mission simulation studies.

  2. Early stages in the evolution of the atmosphere and climate on the Earth-group planets

    NASA Technical Reports Server (NTRS)

    Moroz, V. I.; Mukhin, L. M.

    1977-01-01

    The early evolution of the atmospheres and climate of the Earth, Mars and Venus is discussed, based on a concept of common initial conditions and main processes (besides known differences in chemical composition and outgassing rate). It is concluded that: (1) liquid water appeared on the surface of the earth in the first few hundred million years; the average surface temperature was near the melting point for about the first two eons; CO2 was the main component of the atmosphere in the first 100-500 million years; (2) much more temperate outgassing and low solar heating led to the much later appearance of liquid water on the Martian surface, only one to two billion years ago; the Martian era of rivers, relatively dense atmosphere and warm climate ended as a result of irreversible chemical bonding of CO2 by Urey equilibrium processes; (3) a great lack of water in the primordial material of Venus is proposed; liquid water never was present on the surface of the planet, and there was practically no chemical bonding of CO2; the surface temperature was over 600 K four billion years ago.

  3. Sensitivity of terrestrial ecosystems to elevated atmospheric CO{sub 2}: Comparisons of model simulation studies to CO{sub 2} effect

    SciTech Connect

    Pan, Y. [Marine Biological Lab., Woods Hole, MA (United States)

    1995-06-01

    In the context of a project to compare terrestrial ecosystem models, the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP), we have analyzed how three biogeochemistry models link plant growth to doubled atmospheric CO{sub 2}. A common set of input data was used to drive three biogeochemistry models, BIOME-BGC, CENTURY and TEM. For the continental United States the simulation results show that with doubled CO{sub 2}, NPP increased by 8.7%, 5.0% and 10.8% for TEM, CENTURY and BIOME-BGC, respectively. At the biome level the range of NPP estimates varied considerably among models. TEM-simulated enhancement of NPP ranged from 2% to 28%; CENTURY, from 2% to 9%; and BIOME-BGC, from 4% to 27%. A transect analysis across several biomes along a latitude at 41.5 N shows that the TEM-simulated CO{sub 2} enhancement of NPP ranged from 0% to 22%; CENTURY, from 1% to 10% and BIOME-BGC, from 1% to 63%. In this study, we have investigated the underlying mechanisms of the three models to reveal how increased CO{sub 2} affects photosynthesis rate, water using efficiency and nutrient cycles. The relative importance of these mechanisms in each of the three biogeochemistry models will be discussed.

  4. Impact of improved atmospheric forcing data and soil-vegetation parameters in terrestrial hydrologic modeling over West Africa

    NASA Astrophysics Data System (ADS)

    HE, X.; Kim, H.; Yeh, P. J.; Oki, T.

    2012-12-01

    Several recent studies have shown the importance of land surface-atmosphere coupling in the monsoon system of the West Africa. The African Monsoon Multidisciplinary Analysis (AMMA) has provided an opportunity to investigate model deficiencies in land surface processes by providing high-resolution datasets. In participation with the AMMA Land Surface Model Intercomparison Project (ALMIP2), a global land surface model, the Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO), is regionalized for conducting a high space-time resolution experiment (0.05°, 30 minutes). Multi-year offline simulations using improved rainfall datasets derived from local rain gauges and radar-based products are compared with relative coarse resolution satellite precipitation products, such as Tropical Rainfall Measuring Mission (TRMM; 0.25°, 3 hourly) and Global Satellite Mapping of Precipitation (GSMaP; 0.1°, hourly) to better understand the effect of precipitation on simulated hydrological responses. Sensitivity experiments are also conducted by incorporating more refined distributions of soil-vegetation parameters accounting for natural grid variability to identify how soil properties and interannual vegetation variability are significantly related to water and energy balances in West Africa. Further examination of individual soil parameter and vegetation type is also performed to identify their proper specification in land surface parameterization schemes. Simulations of surface fluxes, soil temperature and soil moisture in dry months and wet months are verified separately by using observations from the AMMA-CATCH observing system as well as several satellite-based products. In general, this study demonstrates that improved forcing and representation of soil-vegetation parameters can improve land surface model simulations from seasonal to interannual time scale.

  5. An early warning indicator for atmospheric blocking events using transfer operators

    E-print Network

    Alexis Tantet; Fiona R. van der Burgt; Henk A. Dijkstra

    2015-03-14

    The existence of persistent midlatitude atmospheric flow regimes with time-scales larger than 5-10 days and indications of preferred transitions between them motivates to develop early warning indicators for such regime transitions. In this paper, we use a hemispheric barotropic model together with estimates of transfer operators on a reduced phase space to develop an early warning indicator of the zonal to blocked flow transition in this model. It is shown that, the spectrum of the transfer operators can be used to study the slow dynamics of the flow as well as the non-Markovian character of the reduction. The slowest motions are thereby found to have time scales of three to six weeks and to be associated with meta-stable regimes (and their transitions) which can be detected as almost-invariant sets of the transfer operator. From the energy budget of the model, we are able to explain the meta-stability of the regimes and the existence of preferred transition paths. Even though the model is highly simplified, the skill of the early warning indicator is promising, suggesting that the transfer operator approach can be used in parallel to an operational deterministic model for stochastic prediction or to assess forecast uncertainty.

  6. An early warning indicator for atmospheric blocking events using transfer operators

    NASA Astrophysics Data System (ADS)

    Tantet, Alexis; van der Burgt, Fiona R.; Dijkstra, Henk A.

    2015-03-01

    The existence of persistent midlatitude atmospheric flow regimes with time-scales larger than 5-10 days and indications of preferred transitions between them motivates to develop early warning indicators for such regime transitions. In this paper, we use a hemispheric barotropic model together with estimates of transfer operators on a reduced phase space to develop an early warning indicator of the zonal to blocked flow transition in this model. It is shown that the spectrum of the transfer operators can be used to study the slow dynamics of the flow as well as the non-Markovian character of the reduction. The slowest motions are thereby found to have time scales of three to six weeks and to be associated with meta-stable regimes (and their transitions) which can be detected as almost-invariant sets of the transfer operator. From the energy budget of the model, we are able to explain the meta-stability of the regimes and the existence of preferred transition paths. Even though the model is highly simplified, the skill of the early warning indicator is promising, suggesting that the transfer operator approach can be used in parallel to an operational deterministic model for stochastic prediction or to assess forecast uncertainty.

  7. Deficit irrigation strategies combined with controlled atmosphere preserve quality in early peaches.

    PubMed

    Falagán, Natalia; Artés, Francisco; Gómez, Perla A; Artés-Hernández, Francisco; Conejero, Wenceslao; Aguayo, Encarna

    2014-10-01

    Due to the water scarcity in the Mediterranean countries, irrigation must be optimized while keeping fruit quality. The effect of deficit irrigation strategies on changes in quality parameters of the early "Flordastar" peaches was studied. The deficit irrigation was programmed according to signal intensity of the maximum daily trunk shrinkage; deficit irrigation plants were irrigated to maintain maximum daily trunk shrinkage signal intensity values close to 1.4 or 1.3 in the case of DI1 or DI2 plants, respectively. Results were compared to a control watered at 150% crop evapotranspiration. Fruits were stored up to 14 days at 0?? and 95% Relative Humidity (RH) in air or in controlled atmosphere (controlled atmosphere; 3-4?kPa O2 and 12-14?kPa CO2), followed by a retail sale period of 4 days at 15?? and 90-95% Relative Humidity in air. Weight losses were lower in controlled atmosphere stored peaches from deficit irrigation. Air-stored fruits developed a more intense red color due to a faster ripening, which was not affected by the type of watering. At harvest, deficit irrigation peaches showed higher soluble solids content, which provided a better sensory evaluation. The soluble phenolic content was initially higher (55.26?±?0.18?mg gallic acid equivalents/100?g fresh weight) and more stable throughout postharvest life in DI1 fruits than in those from the other irrigation treatments. Concerning vitamin C, control fruits at harvest showed higher ascorbic acid than dehydroascorbic acid content (5.43 versus 2.43?mg/100?g fresh weight, respectively), while water stressed peaches showed the opposite results. The combination of DI2 and controlled atmosphere storage allowed saving a significant amount of water and provided peaches with good overall quality, maintaining the bioactive compounds analyzed. PMID:25280939

  8. Terrestrial sequestration

    ScienceCinema

    Charlie Byrer

    2010-01-08

    Terrestrial sequestration is the enhancement of CO2 uptake by plants that grow on land and in freshwater and, importantly, the enhancement of carbon storage in soils where it may remain more permanently stored. Terrestrial sequestration provides an opportunity for low-cost CO2 emissions offsets.

  9. Terrestrial sequestration

    SciTech Connect

    Charlie Byrer

    2008-03-10

    Terrestrial sequestration is the enhancement of CO2 uptake by plants that grow on land and in freshwater and, importantly, the enhancement of carbon storage in soils where it may remain more permanently stored. Terrestrial sequestration provides an opportunity for low-cost CO2 emissions offsets.

  10. The (146,147)Sm-(142,143)Nd systematics of early terrestrial differentiation and the lost continents of the early Earth

    NASA Technical Reports Server (NTRS)

    Harper, Charles L., Jr.; Jacobsen, Stein B.

    1992-01-01

    The very early history of the Earth has been one of the great enduring puzzles in the history of geology. We report evidence which clearly can be described as a vestige of a beginning, because the evidence that we report cannot be interpreted in any other way except as a geochemical signal of processes active in the very early history of the Earth. The evidence itself is a very small anomaly in the abundance of SM-146. The primary aims of this study were to: (1) verify the existence of the 'lost continents' of the Hadean era; and (2) determine their mean age.

  11. Evidence for 182Hf in the early Solar System and constraints on the timescale of terrestrial accretion and core formation

    Microsoft Academic Search

    Charles L. Harper; Stein B. Jacobsen

    1996-01-01

    We present evidence from tungsten (W) isotopic measurements consistent with the presence of live 182Hf (T1\\/2 = 9 Ma) in the early solar system. This is based on the observation of a well-resolved deficit of about four parts in ten thousand in the ratio 182W\\/183W in W separated from the Toluca iron meteorite. This deficit is interpreted as an excess

  12. Influences of Forest Tree Species and Early Spring Temperature on Surface-Atmosphere Transfers of Water and Carbon in the Northeastern U.S.

    NASA Astrophysics Data System (ADS)

    Hadley, J. L.; Kuzeja, P.; Mulcahy, T.; Singh, S.

    2008-12-01

    Influences of Forest Tree Species and Early Spring Temperature on Surface-Atmosphere Transfers of Water and Carbon in the Northeastern U.S. Julian Hadley, Paul Kuzeja, Safina Singh and Thomas Mulcahy Transfers of water vapor from terrestrial ecosystems to the atmosphere affect regional hydrology, weather and climate over short time scales, and forest-atmosphere CO2 exchange affects global climate over long timescales. To better understand these effects for forests dominated by two very different tree species, we measured forest-atmosphere water vapor and CO2 transfers by the eddy flux technique to at two sites in central Massachusetts USA for three years. Average annual evapotranspiration (ET) for a young deciduous forest dominated by red oak (Quercus rubra L., the most abundant tree species in the area), was about 430 mm or 25 percent greater than for a coniferous forest dominated by 100 to 230 year old eastern hemlock (Tsuga canadensis L.). The difference in ET was most pronounced in July and August when the deciduous forest lost about 50 percent more water by ET in the average year (192 mm for oak forest versus 130 mm for hemlock). These data indicate that if deciduous trees with similar physiology to red oak replace hemlocks, summertime ET will increase while summer streamflow, soil water content and the extent of year- round wetlands will decrease. Increased summertime ET should also lead to slightly higher regional atmospheric humidity and precipitation. Hemlock-to-deciduous forest conversion has occurred from North Carolina to southern New England and is continuing northward as a lethal insect pest, the hemlock woolly adelgid (Adelges tsugae Annand) continues to kill hemlocks. Average annual carbon storage for the old hemlock forest in our study was about 3.3 Mg C/ha, nearly equal to the average for the deciduous forest, 3.5 Mg C/ha. This calls into question ecological theory that predicts large declines in the rate of carbon uptake for old forests, and indicates that annual carbon storage will not necessarily increase over the long term after hemlock trees are killed by the hemlock woolly adelgid and replaced by deciduous species. Maximum monthly carbon storage in the hemlock forest occurred in spring (April and May) and was enhanced by early soil thawing and cessation of nighttime frost. This pattern is probably common to many evergreen conifers in the northeastern U.S., so climate warming that includes an earlier end to freezing temperatures in spring should increase C storage by conifer forests in the northeastern U.S. - unless this effect is canceled out by reduced C uptake or enhanced C loss due to changes in summer and fall climate.

  13. Toward understanding early Earth evolution: Prescription for approach from terrestrial noble gas and light element records in lunar soils

    PubMed Central

    Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.

    2008-01-01

    Because of the almost total lack of geological record on the Earth's surface before 4 billion years ago, the history of the Earth during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light elements such as He, N, O, Ne, and Ar would shed a new light on this dark age in the Earth's history and resolve three of the most fundamental questions in earth science: the onset time of the geomagnetic field, the appearance of an oxygen atmosphere, and the secular variation of an Earth–Moon dynamical system. PMID:19001263

  14. Sulfur in the Early Martian Atmosphere Revisited: Experiments with a 3-D Global Climate Model

    NASA Astrophysics Data System (ADS)

    Kerber, L.; Forget, F.; Wordsworth, R.

    2013-09-01

    Data returned from the surface of Mars during the 1970s revealed intriguing geological evidence for a warmer and wetter early martian climate. Dendritic valley networks were discovered by Mariner 9 on ancient Noachian terrain [1], indicating that liquid water had flowed across the surface in the distant past. Since this time, geological investigations into early Martian history have attempted to ascertain the nature and level of activity of the early Martian hydrological cycle [e.g. 2-5] while atmospheric modeling efforts have focused on how the atmosphere could be warmed to temperatures great enough to sustain such activity [see 6-7 for reviews]. Geological and spectroscopic investigations have refined the history and chronology of Noachian Mars over time, and circulation of liquid water has been invoked to explain several spatially and temporally distinct morphological and chemical signatures found in the geological record. Detections of iron and magnesium-rich clays are widespread in the oldest Martian terrains, suggesting a period of pH-neutral aqueous alteration [e.g., 8]. Valley network incision also took place during the Noachian period [9]. Some chains of river valleys and craters lakes extend for thousands of kilometers, suggesting temperatures at least clement enough for sustained ice-covered flow [3,10]. The commencement of valley network incision is not well constrained, but the period of Mg/Fe clay formation appears to have ended before the termination of valley network formation, as the visible fluvial systems appear to have remobilized existing clays rather than forming them [5,8]. There is also evidence that the cessation of valley network formation was abrupt [11]. Towards the end of the Noachian, erosion rates appear to have been significantly higher than during subsequent periods, a process that has also been attributed to aqueous processes [12]. A period of sulfate formation followed, likely characterized by acidic, evaporitic playa environments [8]. A successful working model for the early Martian atmosphere and hydrosphere must be able not only to produce conditions suitable for liquid water at the surface, but also to explain how the nature of this aqueous activity changed over time and eventually diminished. There are two major end-member hypotheses: first, that early Mars was wet and warm, with a sustained greenhouse that made it possible for liquid water to be stable on the surface for extended periods [e.g., 2, 12-14], and second, that early Mars was generally cold, and that most of the aqueous alteration took place underground [3,5] or during transient warm periods tied to impact cratering [15], or volcanism [16]. In both of these scenarios it is generally agreed that in order to make valley networks and sulfate deposits, a hydrological cycle is needed which is able to recycle water from the lowlands back to the highlands (i.e., the one-time emptying of a regional aquifer would not be sufficient to create the observed features) [4,17]. This would require some precipitation to fall on the southern highlands, either flowing overland or filtering into groundwater aquifers. In both cases, volcanic gases (especially SO2) have been suggested as a possible way of creating either a sustained or transient greenhouse. Several researchers have tested the addition of SO2 to climate models in order to assess whether it would provide an adequate amount of greenhouse warming to allow liquid water to flow across the surface [18-21], with differing results. Postawko and Kuhn [18] found a warming effect of 14 K in a 0.1 bar atmosphere with an SO2 abundance of 1000 ppm. Johnson et al. [20] used a 3-D global circulation model and found a warming of 15-25 K for 245 ppm of SO2 in a dry 0.5 bar atmosphere. Tian et al. [21] used a 1-D model to explore a wide range of SO2 mixing values and CO2 partial pressures, finding a warming of around ~25 K for 100 ppm in a 0.5 bar atmosphere with a fully saturated troposphere (~40 K for a 1 bar atmosphere). These authors also included the effect of sulfate aerosol particles, whi

  15. Workshop on Oxygen in the Terrestrial Planets

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in Lunar Metal Grains: Solar, Lunar or Terrestrial Origin? 22) Isotopic Zoning in the Inner Solar System; 23) Redox Conditions on Small Bodies; 24) Determining the Oxygen Fugacity of Lunar Pyroclastic Glasses Using Vanadium Valence - An Update; 25) Mantle Redox Evolution and the Rise of Atmospheric O2; 26) Variation of Kd for Fe-Mg Exchange Between Olivine and Melt for Compositions Ranging from Alkaline Basalt to Rhyolite; 27) Determining the Partial Pressure of Oxygen (PO,) in Solutions on Mars; 28) The Influence of Oxygen Environment on Kinetic Properties of Silicate Rocks and Minerals; 29) Redox Evolution of Magmatic Systems; 30) The Constancy of Upper Mantlefo, Through Time Inferred from V/Sc Ratios in Basalts: Implications for the Rise in Atmospheric 0 2; 31) Nitrogen Solubility in Basaltic Melt. Effects of Oxygen Fugacity, Melt Composition and Gas Speciation; 32) Oxygen Isotope Anomalies in the Atmospheres of Earth and Mars; 33) The Effect of Oxygen Fugacity on Interdiffusion of Iron and Magnesium in Magnesiowiistite 34) The Calibration of the Pyroxene Eu-Oxybarometer for the Martian Meteorites; 35) The Europium Oxybarometer: Power and Pitfalls; 36) Oxygen Fugacity of the Martian Mantle from PigeoniteMelt Partitioning of Samarium, Europium and Gadolinium; 37) Oxidation-Reduction Processes on the Moon: Experimental Verification of Graphite Oxidation in the Apollo 17 Orange Glasses; 38) Oxygen and Core Formation in the Earth; 39) Geologic Record of the Atmospheric Sulfur Chemistry Before the Oxygenation of the Early Earth s Atmosphere; 40) Comparative Planetary Mineralogy: V/(CrCAl) Systematics in Chromite as an Indicator of Relative Oxygen Fugacity; 41) How Well do Sulfur Isotopes Constrain Oxygen Abundance in the Ancient Atmospheres? 42) Experimental Constraints on the Oxygen Isotope (O-18/ O-16) Fractionation in the Ice vapor and Adsorbant vapor Systems of CO2 at Conditions Relevant to the Surface of Mars; 43) Micro-XANES Measurements on Experimental Spinels andhe Oxidation State of Vanadium in Spinel-Melt Pairs; 44) Testing the Magma Ocean Hypothesis Using

  16. Evaluation of terrestrial carbon cycle models through simulations of the seasonal cycle of atmospheric CO2: First results of a model intercomparison study

    Microsoft Academic Search

    M. Heimann; R. D. Otto; I. C. Prentice; W. Sauf; A. Schloss; S. Sitch; U. Wittenberg; G. Würth; J. Melillo; B. Moore

    1998-01-01

    Results of an intercomparison among terrestrial biogeochemical models (TBMs) are reported, in which one diagnostic and five prognostic models have been run with the same long-term climate forcing. Monthly fields of net ecosystem production (NEP), which is the difference between net primary production (NPP) and heterotrophic respiration RH, at 0.5° resolution have been generated for the terrestrial biosphere. The monthly

  17. A Grid of NLTE Line-blanketed Model Atmospheres of Early B-Type Stars

    NASA Astrophysics Data System (ADS)

    Lanz, Thierry; Hubeny, Ivan

    2007-03-01

    We have constructed a comprehensive grid of 1540 metal line-blanketed, NLTE, plane-parallel, hydrostatic model atmospheres for the basic parameters appropriate to early B-type stars. The BSTAR2006 grid considers 16 values of effective temperatures, 15,000 K<=Teff<=30,000 K with 1000 K steps, 13 surface gravities, 1.75<=logg<=4.75 with 0.25 dex steps, six chemical compositions, and a microturbulent velocity of 2 km s-1. The lower limit of logg for a given effective temperature is set by an approximate location of the Eddington limit. The selected chemical compositions range from twice to one-tenth of the solar metallicity and metal-free. Additional model atmospheres for B supergiants (logg<=3.0) have been calculated with a higher microturbulent velocity (10 km s-1) and a surface composition that is enriched in helium and nitrogen and depleted in carbon. This new grid complements our earlier OSTAR2002 grid of O-type stars (our Paper I). The paper contains a description of the BSTAR2006 grid and some illustrative examples and comparisons. NLTE ionization fractions, bolometric corrections, radiative accelerations, and effective gravities are obtained over the parameter range covered by the grid. By extrapolating radiative accelerations, we have determined an improved estimate of the Eddington limit in absence of rotation between 55,000 and 15,000 K. The complete BSTAR2006 grid is available at the TLUSTY Web site.

  18. Earth's early atmosphere as seen from carbon and nitrogen isotopic analysis of Archean sediments

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.; Carr, L. P.; Gilmour, I.; Pillinger, C. T.

    1986-01-01

    The origin and evolution of the Earth's early atmosphere has long been a topic of great interest but determination of actual compositions over geologic time is a difficult problem. However, recent systematic studies of stromatolite deposits (Precambrian Paleobiology Research Group) has extended our knowledge of Archean ecosystems. It has been shown that many stromatolite deposits have undergone negligible alteration since their time of formation. The discovery of primary fluid inclusions within unaltered 3.5 b.y. old Archiean sediments and the observation that the 3.3 b.y. old Barberton cherts have remained closed to argon loss and have not been subjected to thermal metamorphism suggests that an opportunity exists for the direct measurement of the volatile constituents present at their time of formation. Of primary interest to this study was the possibility that the stromatolites and other Archean sediments might retain a vestige of the atmosphere and thus afford an indication of the variations in carbon dioxide and nitrogen isotopic compositions with time. A suite of essentially unaltered Archean stromatolites and the cherts of different ages and geologic sites have been analyzed for their trapped carbon dioxide and nitrogen compositions by the stepped combustion extraction tech nique utilizing static mass spectrometers for the isotope measurements.

  19. Fractal and Multifractal Analysis of the Rise of Oxygen in Earth's Early Atmosphere

    E-print Network

    Satish Kumar; Manfred Cuntz; Zdzislaw E. Musielak

    2014-12-16

    The rise of oxygen in Earth's atmosphere that occurred 2.4 to 2.2 billion years ago is known as the Earth's Great Oxidation, and its impact on the development of life on Earth has been profound. Thereafter, the increase in Earth's oxygen level persisted, though at a more gradual pace. The proposed underlying mathematical models for these processes are based on physical parameters whose values are currently not well-established owing to uncertainties in geological and biological data. In this paper, a previously developed model of Earth's atmosphere is modified by adding different strengths of noise to account for the parameters' uncertainties. The effects of the noise on the time variations of oxygen, carbon and methane for the early Earth are investigated by using fractal and multifractal analysis. We show that the time variations following the Great Oxidation cannot properly be described by a single fractal dimension because they exhibit multifractal characteristics. The obtained results demonstrate that the time series as obtained exhibit multifractality caused by long-range time correlations.

  20. An early warning indicator for atmospheric blocking events using transfer operators

    E-print Network

    Tantet, Alexis; Dijkstra, Henk A

    2015-01-01

    The existence of persistent midlatitude atmospheric flow regimes with time-scales larger than 5-10 days and indications of preferred transitions between them motivates to develop early warning indicators for such regime transitions. In this paper, we use a hemispheric barotropic model together with estimates of transfer operators on a reduced phase space to develop an early warning indicator of the zonal to blocked flow transition in this model. It is shown that, the spectrum of the transfer operators can be used to study the slow dynamics of the flow as well as the non-Markovian character of the reduction. The slowest motions are thereby found to have time scales of three to six weeks and to be associated with meta-stable regimes (and their transitions) which can be detected as almost-invariant sets of the transfer operator. From the energy budget of the model, we are able to explain the meta-stability of the regimes and the existence of preferred transition paths. Even though the model is highly simplified,...

  1. A simplified model for calculating atmospheric radionuclide transport and early health effects from nuclear reactor accidents

    SciTech Connect

    Madni, I.K. [Brookhaven National Lab., Upton, NY (United States); Cazzoli, E.G.; Khatib-Rahbar, M. [Energy Research, Inc., Rockville, MD (United States)

    1995-11-01

    During certain hypothetical severe accidents in a nuclear power plant, radionuclides could be released to the environment as a plume. Prediction of the atmospheric dispersion and transport of these radionuclides is important for assessment of the risk to the public from such accidents. A simplified PC-based model was developed that predicts time-integrated air concentration of each radionuclide at any location from release as a function of time integrated source strength using the Gaussian plume model. The solution procedure involves direct analytic integration of air concentration equations over time and position, using simplified meteorology. The formulation allows for dry and wet deposition, radioactive decay and daughter buildup, reactor building wake effects, the inversion lid effect, plume rise due to buoyancy or momentum, release duration, and grass height. Based on air and ground concentrations of the radionuclides, the early dose to an individual is calculated via cloudshine, groundshine, and inhalation. The model also calculates early health effects based on the doses. This paper presents aspects of the model that would be of interest to the prediction of environmental flows and their public consequences.

  2. Application of 34S analysis for elucidating terrestrial, marine and freshwater ecosystems: Evidence of animal movement/husbandry practices in an early Viking community around Lake Mývatn, Iceland

    NASA Astrophysics Data System (ADS)

    Sayle, Kerry L.; Cook, Gordon T.; Ascough, Philippa L.; Hastie, Helen R.; Einarsson, Árni; McGovern, Thomas H.; Hicks, Megan T.; Edwald, Ágústa; Friðriksson, Adolf

    2013-11-01

    Carbon and nitrogen stable isotope ratios (?13C and ?15N) have been used widely in archaeology to investigate palaeodiet. Sulphur stable isotope ratios (?34S) have shown great promise in this regard but the potential of this technique within archaeological science has yet to be fully explored. Here we report ?34S, ?13C and ?15N values for 129 samples of animal bone collagen from Skútustaðir, an early Viking age (landnám) settlement in north-east Iceland. This dataset represents the most comprehensive study to date of its kind on archaeological material and the results show a clear offset in ?34S values between animals deriving their dietary resources from terrestrial (mean = +5.6 ± 2.8‰), freshwater (mean = -2.7 ± 1.4‰) or marine (mean = +15.9 ± 1.5‰) reservoirs (with the three food groups being significantly different at 2?). This offset allows reconstruction of the dietary history of domesticated herbivores and demonstrates differences in husbandry practices and animal movement/trade, which would be otherwise impossible using only ?13C and ?15N values. For example, several terrestrial herbivores displayed enriched bone collagen ?34S values compared to the geology of the Lake Mývatn region, indicating they may have been affected by sea-spray whilst being pastured closer to the coast, before being traded inland. Additionally, the combination of heavy ?15N values coupled with light ?34S values within pig bone collagen suggests that these omnivores were consuming freshwater fish as a significant portion of their diet. Arctic foxes were also found to be consuming large quantities of freshwater resources and radiocarbon dating of both the pigs and foxes confirmed previous studies showing that a large freshwater radiocarbon (14C) reservoir effect exists within the lake. Overall, these stable isotope and 14C data have important implications for obtaining a fuller reconstruction of the diets of the early Viking settlers in Iceland, and may allow a clearer identification of the marine and/or freshwater 14C reservoir effects that are known to exist in human bone collagen.

  3. Filling-In of Broad Far-Red Solar Lines by Terrestrial Fluorescence and Atmospheric Raman Scattering as Detected by SCIAMACHY Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Joiner, J.; Yoshida, Y.; Vasilkov, A. P.; Middleton, E. M.; Campbell, P. K. E.; Yoshida, Y.; Kuze, A.; Corp, L. A.

    2011-01-01

    Global mapping of terrestrial vegetation fluorescence from space has recently been accomplished with high spectral resolution measurements from the Japanese Greenhouse gases Observing SATellite (GOSAT). These data are of interest because they can potentially provide global information on the functional status of vegetation including light use efficiency and global primary productivity that can be used for global carbon cycle modeling. Quantifying the impact of fluorescence on the O2-A band is important as this band is used for cloud- and aerosol-characterization for other trace-gas retrievals including CO2. Here, we demonstrate that fluorescence information can be derived from space using potentially lower-cost hyperspectral instrumentation, i.e., more than an order of magnitude less spectral resolution than GOSAT, with a relatively simple algorithm. As a demonstration, we use the filling-in of one of the few wide and deep solar Fraunhofer lines in the red and far-red chlorophylla fluorescence bands, the calcium II line near 866 nm, to retrieve fluorescence with the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) satellite instrument. Although the signal from vegetation fluorescence is extremely weak at 866 nm, our results suggest that useful information may be obtained after adjustments are made to the observed spectra to correct for instrumental artifacts. We compare fluorescence from SCIAMACHY with that retrieved at 758 and 770 nm from similarly-corrected GOSAT data as well with the Enhanced Vegetation Index (EVI) from the MODerate-resolution Imaging Spectroradiometer (MODIS). We also show that filling-in occurs at 866 nm over barren areas, possibly originating from luminescent minerals in rock and soil.

  4. Combined147,146Sm-143,142Nd constraints on the longevity and residence time of early terrestrial crust

    NASA Astrophysics Data System (ADS)

    Roth, Antoine S. G.; Bourdon, Bernard; Mojzsis, Stephen J.; Rudge, John F.; Guitreau, Martin; Blichert-Toft, Janne

    2014-06-01

    silicate differentiation controlled the composition of Earth's oldest crust. Inherited 142Nd anomalies in Archean rocks are vestiges of the mantle-crust differentiation before ca. 4300 Ma. Here we report new whole-rock 147,146Sm-143,142Nd data for the Acasta Gneiss Complex (AGC; Northwest Territories, Canada). Our 147Sm-143Nd data combined with literature data define an age of 3371 ± 141 Ma (2 SD) and yield an initial ?143Nd of -5.6 ± 2.1. These results are at odds with the Acasta zircon U-Pb record, which comprises emplacement ages of 3920-3960 Ma. Ten of our thirteen samples show 142Nd deficits of -9.6 ± 4.8 ppm (2 SD) relative to the modern Earth. The discrepancy between 142Nd anomalies and a mid-Archean 147Sm-143Nd age can be reconciled with Nd isotope reequilibration of the AGC during metamorphic perturbations at ca. 3400 Ma. A model age of ca. 4310 Ma is derived for the early enrichment of the Acasta source. Two compositional end-members can be identified: a felsic component with 142Nd/144Nd identical to the modern Earth and a mafic component with 142Nd/144Nd as low as -14.1 ppm. The ca. 4310 Ma AGC source is ˜200 Myr younger than those estimated for Nuvvuagittuq (northern Québec) and Isua (Itsaq Gneiss Complex, West Greenland). The AGC does not have the same decoupled Nd-Hf isotope systematics as these other two terranes, which have been attributed to the crystallization of an early magma ocean. The Acasta signature rather is ascribed to the formation of Hadean crust that was preserved for several hundred Myr. Its longevity can be linked to 142Nd evolution in the mantle and does not require slow mantle stirring times nor modification of its convective mode.

  5. Atmosphere

    NSDL National Science Digital Library

    University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

    2003-01-01

    What is this atmosphere that surrounds the Earth? This instructional tutorial, part of an interactive laboratory series for grades 8-12, introduces students to the structure, effects, and components of the atmosphere. Here students investigate the composition of the atmosphere; effects of temperature, pressure, and ozone; the greenhouse effect; and how Earth compares with other planets. Interactive activities present students with opportunities to explore ideas and answer questions about the atmosphere, including its structure, the making of ozone, rocket launching, and measuring the atmosphere. Pop-up boxes provide additional information on topics such as dust, rain, and atmospheric composition. Students complete a final written review of six questions about the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

  6. XUV-Exposed, Non-Hydrostatic Hydrogen-Rich Upper Atmospheres of Terrestrial Planets. Part II: Hydrogen Coronae and Ion Escape

    PubMed Central

    Lammer, Helmut; Holmström, Mats; Panchenko, Mykhaylo; Odert, Petra; Erkaev, Nikolai V.; Leitzinger, Martin; Khodachenko, Maxim L.; Kulikov, Yuri N.; Güdel, Manuel; Hanslmeier, Arnold

    2013-01-01

    Abstract We studied the interactions between the stellar wind plasma flow of a typical M star, such as GJ 436, and the hydrogen-rich upper atmosphere of an Earth-like planet and a “super-Earth” with a radius of 2 REarth and a mass of 10 MEarth, located within the habitable zone at ?0.24?AU. We investigated the formation of extended atomic hydrogen coronae under the influences of the stellar XUV flux (soft X-rays and EUV), stellar wind density and velocity, shape of a planetary obstacle (e.g., magnetosphere, ionopause), and the loss of planetary pickup ions on the evolution of hydrogen-dominated upper atmospheres. Stellar XUV fluxes that are 1, 10, 50, and 100 times higher compared to that of the present-day Sun were considered, and the formation of high-energy neutral hydrogen clouds around the planets due to the charge-exchange reaction under various stellar conditions was modeled. Charge-exchange between stellar wind protons with planetary hydrogen atoms, and photoionization, lead to the production of initially cold ions of planetary origin. We found that the ion production rates for the studied planets can vary over a wide range, from ?1.0×1025 s?1 to ?5.3×1030 s?1, depending on the stellar wind conditions and the assumed XUV exposure of the upper atmosphere. Our findings indicate that most likely the majority of these planetary ions are picked up by the stellar wind and lost from the planet. Finally, we estimated the long-time nonthermal ion pickup escape for the studied planets and compared them with the thermal escape. According to our estimates, nonthermal escape of picked-up ionized hydrogen atoms over a planet's lifetime within the habitable zone of an M dwarf varies between ?0.4 Earth ocean equivalent amounts of hydrogen (EOH) to <3 EOH and usually is several times smaller in comparison to the thermal atmospheric escape rates. Key Words: Stellar activity—Low-mass stars—Early atmospheres—Earth-like exoplanets—Energetic neutral atoms—Ion escape—Habitability. Astrobiology 13, 1030–1048. PMID:24283926

  7. Differential Expression of Metallothionein Isoforms in Terrestrial Snail Embryos Reflects Early Life Stage Adaptation to Metal Stress

    PubMed Central

    Baurand, Pierre-Emmanuel; Pedrini-Martha, Veronika; de Vaufleury, Annette; Niederwanger, Michael; Capelli, Nicolas; Scheifler, Renaud; Dallinger, Reinhard

    2015-01-01

    The aim of this study was to analyze the expression of three metallothionein (MT) isoform genes (CdMT, CuMT and Cd/CuMT), already known from adults, in the Early Life Stage (ELS) of Cantareus aspersus. This was accomplished by detection of the MT isoform-specific transcription adopting Polymerase Chain Reaction (PCR) amplification and quantitative Real Time (qRT)-PCR of the three MT genes. Freshly laid eggs were kept for 24 hours under control conditions or exposed to three cadmium (Cd) solutions of increasing concentration (5, 10, and 15 mg Cd/L). The transcription of the three MT isoform genes was detected via PCR in 1, 6 and 12-day-old control or Cd-exposed embryos. Moreover, the transcription of this isoform genes during development was followed by qRT-PCR in 6 and 12-day-old embryos. Our results showed that the CdMT and Cd/CuMT genes, but not the CuMT gene, are expressed in embryos at the first day of development. The transcription of the 3 MT genes in control embryos increased with development time, suggesting that the capacities of metal regulation and detoxification may have gradually increased throughout embryogenesis. However in control embryos, the most highly expressed MT gene was that of the Cd/CuMT isoform, whose transcription levels greatly exceeded those of the other two MT genes. This contrasts with the minor significance of this gene in adult snails and suggests that in embryos, this isoform may play a comparatively more important role in metal physiology compared to adult individuals. This function in adult snails appears not to be related to Cd detoxification. Instead, snail embryos responded to Cd exposure by over-expression of the CdMT gene in a concentration-dependent manner, whereas the expression of the Cd/CuMT gene remained unaffected. Moreover, our study demonstrates the ability of snail embryos to respond very early to Cd exposure by up-regulation of the CdMT gene. PMID:25706953

  8. Terrestrial Planet Atmospheres. The Moon's Sodium Atmosphere

    E-print Network

    Walter, Frederick M.

    for a Planet · Equator heated more than poles · Hadley cell transport heat poleward of greenhouse gases--warms planet · Water vapor carried to high alFtude condenses ­ Large? ­ Smaller planet mass? ­ Lightweight gases? #12;Venus and the Runaway Greenhouse

  9. Phosphorus Redox on the Early Earth: First Identification of Low-Oxidation State Phosphorus Compounds in Terrestrial Samples

    NASA Astrophysics Data System (ADS)

    Block, K. M.; Pasek, M. A.

    2008-12-01

    Phosphorus is one of the key elements in biochemical systems, playing an important role in metabolism as ATP and other coenzymes, in replication as DNA and RNA, and in cellular structure as phospholipids. The geochemical cycling of phosphorus on the Earth is usually confined to the rock cycle- redox reactions of phosphorus are never considered. However, it has been proposed that redox reactions of phosphorus were important on the early Earth (Pasek, PNAS 2008). Indeed, such a suggestion is buttressed by the discovery of condensed phosphate formation linked to the oxidation of reduced P compounds. However, prior to the present work, there has been no report of these P compounds in geologic samples. Here we report the first occurrence of reduced P in samples of fulgurites, the glassy material resulting from the fusion of sand, soil, or rock during a lightning strike. On average, lightning strikes the Earth's surface at a rate of approximately 65 times per second (Krider et al., J. Geophys. Res.,1968) exposing target areas to extreme energy dissipation and temperatures. Through electron microprobe analyses and NMR we have identified naturally formed metal droplets containing Fe and P within several fulgurite samples and Ca-phosphite compounds. These droplets are highly reduced compared to the original material and are not naturally present in the target area, rather they were formed through the rapid, intense heating and quenching experienced during fulgurite formation. This process provides a natural means to create localized environments with greater than normal abundances of reduced Fe and P, less commonly found on Earth's surface than their oxidized counterparts. In particular, small areas that receive repeated lightning strikes due to topography or local weather patterns (e.g. hilltops) could potentially house unique microhabitats with reduced elements available for biological use.

  10. Methane Fluxes Between Terrestrial Ecosystems and the Atmosphere at Northern High Latitudes During the Past Century: A retrospective analysis with a process-based biogeochemistry model

    E-print Network

    Zhuang, Qianlai.

    We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century ...

  11. Terrestrial Biomarkers for Early Life on Earth as Analogs for Possible Martian Life Forms: Examples of Minerally Replaced Bacteria and Biofilms From the 3.5 - 3.3-Ga Barberton Greenstone Belt, South Africa

    NASA Technical Reports Server (NTRS)

    Westall, F.; McKay, D. S.; Gibson, E. K.; deWit, M. J.; Dann, J.; Gerneke, D.; deRonde, C. E. J.

    1998-01-01

    The search for extraterrestrial life and especially martian life hinges on a variety of methods used to identify vestiges of what we could recognize as life, including chemical signatures, morphological fossils, and biogenic precipitates. Although the possibility of extant life on Mars (subsurface) is being considered, most exploration efforts may be directed toward the search for fossil life. Geomorphological evidence points to a warmer and wetter Mars early on in its history, a scenario that encourages comparison with the early Earth. For this reason, study of the early terrestrial life forms and environment in which they lived may provide clues as to how to search for extinct martian life. As a contribution to the early Archean database of terrestrial microfossils, we present new data on morphological fossils from the 3.5-3.3-Ga Barberton greenstone belt (BGB), South Africa. This study underlines the variety of fossil types already present in some of the oldest, best-preserved terrestrial sediments, ranging from minerally replaced bacteria and bacteria molds of vaRious morphologies (coccoid, coccobacillus, bacillus) to minerally replaced biofilm. Biofilm or extracellular polymeric substance (EPS) is produced by bacteria and appears to be more readily fossilisable than bacteria themselves. The BGB fossils occur in shallow water to subaerial sediments interbedded with volcanic lavas, the whole being deposited on oceanic crust. Penecontemporaneous silicification of sediments and volcanics resulted in the chertification of the rocks, which were later subjected to low-grade metamorphism (lower greenschist).

  12. Evidence for a (15)N positive excursion in terrestrial foodwebs at the Middle to Upper Palaeolithic transition in south-western France: Implications for early modern human palaeodiet and palaeoenvironment.

    PubMed

    Bocherens, Hervé; Drucker, Dorothée G; Madelaine, Stéphane

    2014-04-01

    The Middle to Upper Palaeolithic transition around 35,000 years ago coincides with the replacement of Neanderthals by anatomically modern humans in Europe. Several hypotheses have been suggested to explain this replacement, one of them being the ability of anatomically modern humans to broaden their dietary spectrum beyond the large ungulate prey that Neanderthals consumed exclusively. This scenario is notably based on higher nitrogen-15 amounts in early Upper Palaeolithic anatomically modern human bone collagen compared with late Neanderthals. In this paper, we document a clear increase of nitrogen-15 in bone collagen of terrestrial herbivores during the early Aurignacian associated with anatomically modern humans compared with the stratigraphically older Châtelperronian and late Mousterian fauna associated with Neanderthals. Carnivores such as wolves also exhibit a significant increase in nitrogen-15, which is similar to that documented for early anatomically modern humans compared with Neanderthals in Europe. A shift in nitrogen-15 at the base of the terrestrial foodweb is responsible for such a pattern, with a preserved foodweb structure before and after the Middle to Upper Palaeolithic transition in south-western France. Such an isotopic shift in the terrestrial ecosystem may be due to an increase in aridity during the time of deposition of the early Aurignacian layers. If it occurred across Europe, such a shift in nitrogen-15 in terrestrial foodwebs would be enough to explain the observed isotopic trend between late Neanderthals and early anatomically modern humans, without any significant change in the diet composition at the Middle to Upper Palaeolithic transition. PMID:24630359

  13. Carbon dioxide on the early earth

    Microsoft Academic Search

    James C. G. Walker

    1985-01-01

    This paper uses arguments of geochemical mass balance to arrive at an estimate of the partial pressure of carbon dioxide in the terrestrial atmosphere very early in earth history. It appears that this partial pressure could have been as large as 10 bars. This large estimate depends on two key considerations. First, volatiles were driven out of the interior of

  14. A comparison of lyman alpha and He lambda 10830 line structures and variations in early-type star atmospheres

    NASA Technical Reports Server (NTRS)

    Meisel, D. D.

    1974-01-01

    Line profiles were first obtained at maximum velocity separation of the spectroscopic binary Spica (alpha Vir), and then high resolution spectrophotometric images of selected features in the 1.1 micron spectrum of Comet Kohoutek were obtained in order to gain insight into the structures and variations in early-type star atmospheres.

  15. Early plume expansion in atmospheric pressure midinfrared laser ablation of water-rich targets Zhaoyang Chen and Akos Vertes*

    E-print Network

    Vertes, Akos

    Early plume expansion in atmospheric pressure midinfrared laser ablation of water-rich targets. The absorption of laser light by water below the surface plays an important role during water ablation and phase a one-dimensional fluid dynamics model for the ablation of water-rich targets by nanosecond infrared

  16. Paleoclimatic and paleoecological reconstruction of early Miocene terrestrial equatorial deposits, Rusinga and Mfangano Islands, Lake Victoria, Kenya

    NASA Astrophysics Data System (ADS)

    Michel, L. A.; Peppe, D. J.; McNulty, K. P.; Driese, S. G.; Lutz, J.; Nightingale, S.; Maxbauer, D. P.; Horner, W. H.; DiPietro, L. M.; Lehmann, T.; Dunsworth, H. M.; Harcourt-Smith, W. E.; Ogondo, J.

    2012-12-01

    Biological responses to climatic shifts are often studied to inform us on future anthropogenic-driven climate change. However, few of these climatic shifts occur over time scales appropriate to modern change and few occur with biota similar to modern. The Miocene Climatic Optimum is an ideal interval to study because of its rapid duration and because it occurred during the rise and proliferation of apes. The sediments on Rusinga and Mfangano Islands, Lake Victoria, Kenya were deposited between 18 and 20 Ma and record a changing equatorial climate just prior to the Miocene Climate Optimum. This location also offers an opportunity to use multiple proxies to constrain climate and landscape, including paleosol geochemistry, paleobotany and paleontology. Additionally, due to the rich fossil preservation on the islands, climatic shifts are framed within the context of early caterrhine evolution. Here, we report a climate shift recorded through three time slices spanning two formations over ~2 myr. The oldest unit, the Wayando Formation, records an arid, probably open ecosystem with pedogenic calcite rhizoliths, a high groundwater table, poorly-formed paleosols and permineralized sedges. The middle time slice, the Grit Member-Fossil Bed Member contact of the Hiwegi Formation, shows evidence of a local saline lake, with desiccation features, satin-spar after gypsum deposits and salt hoppers. Paleobotanical and sedimentological data from roughly contemporaneous strata indicate a warm, highly seasonal environment that supported a mixture of woodland and forested elements across the landscape. The youngest unit, which is within the Kibanga Member of the Hiwegi Formation, displays demonstrable evidence for a closed-canopy multistoried forest with the presence of tree-stump casts and permineralized root systems within a red-brown paleosol. Within the same paleosol horizon, the dental remains of the catarrhines Proconsul and Dendropithecus have been discovered in situ. This stratum is overlain by a sandstone with preserved leaves. Bulk soil geochemistry and paleobotanical proxies suggest the climate was warm (MAT estimates range = 22.6 - 34.5 °C) and relatively wet (MAP estimates range = 700 - 2,620 mm). This study suggests that tropical Africa may have had a much more dynamic climate leading up to the Miocene Climatic Optimum than previously suggested, and underwent considerable ecosystem reorganization both before and after the Miocene Climatic Optimum.

  17. Terrestrial multi-proxy late Miocene to early Pliocene climate reconstruction of Cook Inlet forearc basin, southern Alaska

    NASA Astrophysics Data System (ADS)

    Mongrain, J. R.; Wooller, M.; Fowell, S. J.; Mccarthy, P. J.; LePain, D.

    2011-12-01

    Understanding the climate and depositional systems in south-central Alaska during initial uplift of the central and western Alaska Range has been hampered by conflicting climatic interpretations and poor age control regarding the timing of exhumation and uplift. This study focuses on the late Miocene to early Pliocene climate record preserved in fluvial depositional systems that crop out near the margin of Cook Inlet forearc basin, south-central Alaska. These data, along with newly published exhumation and uplift ages for the central and western Alaska Range, provide new insights into the relationship between climate and uplift. Climate reconstructions are based on a multi-proxy approach that includes stable carbon isotopic analyses of residual pollen concentrates from palynological preparations, allowing direct comparisons with palynological data from the same samples. The pollen-derived stable carbon isotope data are supplemented with isotopic analyses of bulk sediment and coal. The palynological assemblages indicate prolonged warm conditions, as thermophilic taxa are consistently present. The exception is the youngest sample, which reveals a marked decrease in thermophilic taxa such as Podocarpus, Pterocarya/Cyclocarya, and Fagus and may record the initial cooling of south-central Alaska during the Pliocene. Pollen frequencies indicate relatively humid conditions over the interval from ~10 Ma to ~6.5 Ma, with the wettest conditions occurring ~8 Ma. The ?13C data are used to estimate mean annual precipitation (MAP), which provides supporting evidence of wet conditions between ~7.5 Ma and ~8.5 Ma. Considerable variability in MAP, ranging from 3600 to 300 mm, suggests that generally wet conditions were interrupted by periods of below average precipitation. Increases in precipitation due to uplift of the central and western Alaska Range and related orographic effects are probably not responsible for increases in MAP, as these events postdate the humid interval by ~ 2 Ma, as does the opening of the Bering Strait. However, evidence for thermal climatic optima from 11.5 to 10.5 and 7.5 to 6.5 Ma in North Pacific marine paleoclimate records are taken to indicate warm sea surface temperatures, which may be responsible for high MAP and persistence of thermophilic genera in Cook Inlet.

  18. Filling-in of Far-Red and Near-Infrared Solar Lines by Terrestrial and Atmospheric Effects: Simulations and Space-Based Observations from SCIAMACHY and GOSAT

    NASA Technical Reports Server (NTRS)

    Joiner, J.; Yoshida, Y.; Vasilkov, A. P.; Middleton, E. M.; Campbell, P. K. E.; Yoshida, Y.; Kuse, A.; Corp, L. A.

    2012-01-01

    Mapping of terrestrial vegetation fluorescence from space is of interest because it can potentially provide global information on the functional status of vegetation including light use efficiency and global primary productivity that can be used for global carbon cycle modeling. Space-based measurement of solar-induced chlorophyll fluorescence is challenging, because its signal is small as compared with the much larger reflectance signal. Ground- and aircraft-based approaches have made use of the dark and spectrally-wide O2-A ( approx 760 nm) and O2-B (approx 690 nm) atmospheric features to detect the weak fluorescence signal. More recently, Joiner et al. and Frankenberg et al. focused on longer-wavelength solar Fraunhofer lines that can be observed with space-based instruments such as the currently operational GOSAT. They showed that fluorescence can be detected using Fraunhofer lines away from the far-red chlorophyll-a fluorescence peak even when the surface is relatively bright. Here, we build on that work by developing methodology to correct for instrumental artifacts that produce false filling-in signals that can bias fluorescence retrievals. We also examine other potential sources of filling-in at far-red and NIR wavelengths. Another objective is to explore the possibility of making fluorescence measurements from space with lower spectral resolution instrumentation than the GOSAT interferometer. We focus on the 866nm Ca II solar Fraunhofer line. Very few laboratory and ground-based measurements of vegetation fluorescence have been reported at wavelengths longer than 800 nm. Some results of fluorescence measurements of corn leaves acquired in the laboratory using polychromatic excitation at wavelengths shorter than 665nm show that at 866 nm, the measured signal is of the order of 0.1-0.2 mW/sq m/nm/sr. In this work, we use the following satellite observations: We use SCIAMACHY channel 5 in nadir mode that covers wavelengths between 773 and 1063nm at a spectral resolution of 0.54 nm. GOSAT has two instrument packages: the Thermal And Near-infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) and the Cloud and Aerosol Imager (CAI). We use TANSO-FTS band 1, which extends from approximately 758 to 775nm and we use cloud fraction derived from the CAI. We compare satellite-derived fluorescence with the Enhanced Vegetation Index (EVI), an Aqua/MODIS-derived vegetation reflectance-based index that indicates relative greenness and is used to infer photosynthetic function.

  19. Filling-in of Far-Red and Near-Infrared Solar Lines by Terrestrial and Atmospheric Effects: Simulations and Space-Based Observations from SCHIAMACHY and GOSAT

    NASA Technical Reports Server (NTRS)

    Joiner, J.; Yoshida, Y.; Vasilkov, A. P.; Middleton, E. M.; Campbell, P. K. E.; Kuze, A.; Corp, L. A.

    2012-01-01

    Mapping of terrestrial vegetation fluorescence from space is of interest because it can potentially provide global information on the functional status of vegetation including light use efficiency and global primary productivity that can be used for global carbon cycle modeling. Space-based measurement of solar-induced chlorophyll fluorescence is challenging, because its signal is small as compared with the much larger reflectance signal. Ground- and aircraft-based approaches have made use of the dark and spectrally-wide 02-A (approx 760 nm) and O2-B (approx 690 nm) atmospheric features to detect the weak fluorescence signal. More recently, Joiner et a1. and Frankenberg et a1. focused on longer-wavelength solar Fraunhofer lines that can be observed with space-based instruments such as the currently operational GOSAT. They showed that fluorescence can be detected using Fraunhofer lines away from the far-red chlorophyll-a fluorescence peak even when the surface is relatively bright. Here, we build on that work by developing methodology to correct for instrumental artifacts that produce false filling-in signals that can bias fluorescence retrievals. We also examine other potential sources of filling-in at far-red and NIR wavelengths. Another objective is to explore the possibility of making fluorescence measurements from space with lower spectral resolution instrumentation than the GOSAT interferometer. We focus on the 866 nm Ca II solar Fraunhofer line. Very few laboratory and ground-based measurements of vegetation fluorescence have been reported at wavelengths longer than 800 mn. Some results of fluorescence measurements of corn leaves acquired in the laboratory using polychromatic excitation at wavelengths shorter than 665 nm show that at 866 nm, the measured signal is of the order of 0.1-0.2 mw/sq m/nm/sr. In this work we use the following satellite observations: We use SCIAMACHY channel 5 in nadir mode that covers wavelengths between 773 and 1063 nm at a spectral resolution of 0.54 nm. GOSAT has two instrument packages: the Thermal And Near-infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) and the Cloud and Aerosol Imager (CAI). We use TANSO-FTS band 1, which extends from approximately 758 to 775 mn and we use cloud fraction derived from the CAL We compare satellite-derived fluorescence with the Enhanced Vegetation Index (EVI), an Aqua/MODIS-derived vegetation reflectance-based index that indicates relative greenness and is used to infer photosynthetic function.

  20. Evolution of ore deposits on terrestrial planets

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1991-01-01

    Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars, but not submarine ferromanganese nodules and crusts which have precipitated in oxygenated seawater on earth.

  1. Evolution of ore deposits on terrestrial planets

    NASA Astrophysics Data System (ADS)

    Burns, R. G.

    Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars, but not submarine ferromanganese nodules and crusts which have precipitated in oxygenated seawater on earth.

  2. Mercury in the Canadian Arctic terrestrial environment: an update.

    PubMed

    Gamberg, Mary; Chételat, John; Poulain, Alexandre J; Zdanowicz, Christian; Zheng, Jiancheng

    2015-03-15

    Contaminants in the Canadian Arctic have been studied over the last twenty years under the guidance of the Northern Contaminants Program. This paper provides the current state of knowledge on mercury (Hg) in the Canadian Arctic terrestrial environment. Snow, ice, and soils on land are key reservoirs for atmospheric deposition and can become sources of Hg through the melting of terrestrial ice and snow and via soil erosion. In the Canadian Arctic, new data have been collected for snow and ice that provide more information on the net accumulation and storage of Hg in the cryosphere. Concentrations of total Hg (THg) in terrestrial snow are highly variable but on average, relatively low (<5 ng L(-1)), and methylmercury (MeHg) levels in terrestrial snow are also generally low (<0.1 ng L(-1)). On average, THg concentrations in snow on Canadian Arctic glaciers are much lower than those reported on terrestrial lowlands or sea ice. Hg in snow may be affected by photochemical exchanges with the atmosphere mediated by marine aerosols and halogens, and by post-depositional redistribution within the snow pack. Regional accumulation rates of THg in Canadian Arctic glaciers varied little during the past century but show evidence of an increasing north-to-south gradient. Temporal trends of THg in glacier cores indicate an abrupt increase in the early 1990 s, possibly due to volcanic emissions, followed by more stable, but relatively elevated levels. Little information is available on Hg concentrations and processes in Arctic soils. Terrestrial Arctic wildlife typically have low levels of THg (<5 ?g g(-1) dry weight) in their tissues, although caribou (Rangifer tarandus) can have higher Hg because they consume large amounts of lichen. THg concentrations in the Yukon's Porcupine caribou herd vary among years but there has been no significant increase or decrease over the last two decades. PMID:24861531

  3. Solution of the comoving-frame equation of transfer in spherically symmetric flows. V - Multilevel atoms. [in early star atmospheres

    NASA Technical Reports Server (NTRS)

    Mihalas, D.; Kunasz, P. B.

    1978-01-01

    The coupled radiative transfer and statistical equilibrium equations for multilevel ionic structures in the atmospheres of early-type stars are solved. Both lines and continua are treated consistently; the treatment is applicable throughout a transonic wind, and allows for the presence of background continuum sources and sinks in the transfer. An equivalent-two-level-atoms approach provides the solution for the equations. Calculations for simplified He (+)-like model atoms in parameterized isothermal wind models indicate that subordinate line profiles are sensitive to the assumed mass-loss rate, and to the assumed structure of the velocity law in the atmospheres.

  4. Terrestrial Mammalian Herbivore Response to Declining Levels of Atmospheric CO 2 During the Cenozoic: Evidence from North American Fossil Horses (Family Equidae)

    Microsoft Academic Search

    Bruce J. MacFadden

    The fossil record preserves a wonderfully rich sequence spanning 65 million years of Cenozoic mammals that lived in ancient terrestrial ecosystems. During this time in Earth history, major global climate changes undoubtedly affected the course of mammalian evolution. Similarly, countless biotic interactions, such as competition, contributed to the struggle for existence of particular species. One of the interesting challenges for

  5. Atmospheric Erosion Caused by Stellar Coronal Plasma Flows on Terrestrial Exoplanets within Close-In Habitable Zones of Low Mass Stars

    Microsoft Academic Search

    H. Lammer; N. Terada; Yu. N. Kulikov; H. I. M. Lichtenegger; M. L. Khodachenko; T. Penz

    2008-01-01

    Since low mass M stars show a higher level of stellar activity compared to solar-like stars, and because of the closer orbital distance of their habitable zones compared to that of the Solar System, terrestrial exoplanets within M star habitable zones are expected to be much more strongly influenced by stellar winds and dense plasma ejected from the host star

  6. Terrestrial planet formation

    PubMed Central

    Righter, K.; O’Brien, D. P.

    2011-01-01

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (?106 y), followed by planetesimals to embryos (lunar to Mars-sized objects; few × 106 y), and finally embryos to planets (107–108 y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids. PMID:21709256

  7. Atmospheric control on ground and space based early warning system for hazard linked to ash injection into the atmosphere

    NASA Astrophysics Data System (ADS)

    Caudron, Corentin; Taisne, Benoit; Whelley, Patrick; Garces, Milton; Le Pichon, Alexis

    2014-05-01

    Violent volcanic eruptions are common in the Southeast Asia which is bordered by active subduction zones with hundreds of active volcanoes. The physical conditions at the eruptive vent are difficult to estimate, especially when there are only a few sensors distributed around the volcano. New methods are therefore required to tackle this problem. Among them, satellite imagery and infrasound may rapidly provide information on strong eruptions triggered at volcanoes which are not closely monitored by on-site instruments. The deployment of an infrasonic array located at Singapore will increase the detection capability of the existing IMS network. In addition, the location of Singapore with respect to those volcanoes makes it the perfect site to identify erupting blasts based on the wavefront characteristics of the recorded signal. There are ~750 active or potentially active volcanoes within 4000 kilometers of Singapore. They have been combined into 23 volcanic zones that have clear azimuth with respect to Singapore. Each of those zones has been assessed for probabilities of eruptive styles, from moderate (Volcanic Explosivity Index of 3) to cataclysmic (VEI 8) based on remote morphologic analysis. Ash dispersal models have been run using wind velocity profiles from 2010 to 2012 and hypothetical eruption scenarios for a range of eruption explosivities. Results can be used to estimate the likelihood of volcanic ash at any location in SE Asia. Seasonal changes in atmospheric conditions will strongly affect the potential to detect small volcanic eruptions with infrasound and clouds can hide eruption plumes from satellites. We use the average cloud cover for each zone to estimate the probability of eruption detection from space, and atmospheric models to estimate the probability of eruption detection with infrasound. Using remote sensing in conjunction with infrasound improves detection capabilities as each method is capable of detecting eruptions when the other is 'blind' or 'defened' by adverse atmospheric conditions. According to its location, each volcanic zone will be associated with a threshold value (minimum VEI detectable) depending on the seasonality of the wind velocity profile in the region and the cloud cover.

  8. Forsterite/melt partitioning of argon and iodine: Implications for atmosphere formation by outgassing of an early Martian magma ocean

    NASA Technical Reports Server (NTRS)

    Musselwhite, Donald S.; Drake, Michael J.; Swindle, Timothy D.

    1992-01-01

    Argon and Xe in the Martian atmosphere are radiogenic relative to the Martian mantle if the SNC meteorites are from Mars. Decay of the short lived isotope I-129 to Xe-129 (t sub 1/2 = 16 m.y.) is the most plausible source of the radiogenic Xe. This short half life constrains any process responsible for the elevated Xe-129/Xe-132 ratio of the Martian atmosphere to occur very early in solar system history. Musselwhite et al. proposed that the differential solubility of I and Xe in liquid water played a key role in producing the radiogenic signature in the Martian atmosphere. Here we explore an alternative hypothesis involving purely igneous processes, and motivated in part by new experimental results on the partitioning of I and Xe between minerals and melt.

  9. Pathways to Earth-like atmospheres. Extreme ultraviolet (EUV)-powered escape of hydrogen-rich protoatmospheres.

    PubMed

    Lammer, Helmut; Kislyakova, K G; Odert, P; Leitzinger, M; Schwarz, R; Pilat-Lohinger, E; Kulikov, Yu N; Khodachenko, M L; Güdel, M; Hanslmeier, M

    2011-12-01

    We discuss the evolution of the atmosphere of early Earth and of terrestrial exoplanets which may be capable of sustaining liquid water oceans and continents where life may originate. The formation age of a terrestrial planet, its mass and size, as well as the lifetime in the EUV-saturated early phase of its host star play a significant role in its atmosphere evolution. We show that planets even in orbits within the habitable zone of their host stars might not lose nebular- or catastrophically outgassed initial protoatmospheres completely and could end up as water worlds with CO2 and hydrogen- or oxygen-rich upper atmospheres. If an atmosphere of a terrestrial planet evolves to an N2-rich atmosphere too early in its lifetime, the atmosphere may be lost. We show that the initial conditions set up by the formation of a terrestrial planet and by the evolution of the host star's EUV and plasma environment are very important factors owing to which a planet may evolve to a habitable world. Finally we present a method for studying the discussed atmosphere evolution hypotheses by future UV transit observations of terrestrial exoplanets. PMID:22314970

  10. Terrestrial ecosystems and climatic change

    SciTech Connect

    Emanuel, W.R. (Oak Ridge National Lab., TN (USA)); Schimel, D.S. (Colorado State Univ., Fort Collins, CO (USA). Natural Resources Ecology Lab.)

    1990-01-01

    The structure and function of terrestrial ecosystems depend on climate, and in turn, ecosystems influence atmospheric composition and climate. A comprehensive, global model of terrestrial ecosystem dynamics is needed. A hierarchical approach appears advisable given currently available concepts, data, and formalisms. The organization of models can be based on the temporal scales involved. A rapidly responding model describes the processes associated with photosynthesis, including carbon, moisture, and heat exchange with the atmosphere. An intermediate model handles subannual variations that are closely associated with allocation and seasonal changes in productivity and decomposition. A slow response model describes plant growth and succession with associated element cycling over decades and centuries. These three levels of terrestrial models are linked through common specifications of environmental conditions and constrain each other. 58 refs.

  11. Global modelling of the early Martian climate under a denser CO2 atmosphere: Water cycle and ice evolution

    E-print Network

    Wordsworth, R; Millour, E; Head, J; Madeleine, J -B; Charnay, B

    2012-01-01

    We discuss 3D global simulations of the early Martian climate that we have performed assuming a faint young Sun and denser CO2 atmosphere. We include a self-consistent representation of the water cycle, with atmosphere-surface interactions, atmospheric transport, and the radiative effects of CO2 and H2O gas and clouds taken into account. We find that for atmospheric pressures greater than a fraction of a bar, the adiabatic cooling effect causes temperatures in the southern highland valley network regions to fall significantly below the global average. Long-term climate evolution simulations indicate that in these circumstances, water ice is transported to the highlands from low-lying regions for a wide range of orbital obliquities, regardless of the extent of the Tharsis bulge. In addition, an extended water ice cap forms on the southern pole, approximately corresponding to the location of the Noachian/Hesperian era Dorsa Argentea Formation. Even for a multiple-bar CO2 atmosphere, conditions are too cold to a...

  12. The Geology of the Terrestrial Planets

    NASA Technical Reports Server (NTRS)

    Carr, M. H. (editor); Saunders, R. S.; Strom, R. G.; Wilhelms, D. E.

    1984-01-01

    The geologic history of the terrestrial planets is outlined in light of recent exploration and the revolution in geologic thinking. Among the topics considered are planet formation; planetary craters, basins, and general surface characteristics; tectonics; planetary atmospheres; and volcanism.

  13. Space Vehicle Terrestrial Environment Design Requirements Guidelines

    NASA Technical Reports Server (NTRS)

    Johnson, Dale L.; Keller, Vernon W.; Vaughan, William W.

    2006-01-01

    The terrestrial environment is an important driver of space vehicle structural, control, and thermal system design. NASA is currently in the process of producing an update to an earlier Terrestrial Environment Guidelines for Aerospace Vehicle Design and Development Handbook. This paper addresses the contents of this updated handbook, with special emphasis on new material being included in the areas of atmospheric thermodynamic models, wind dynamics, atmospheric composition, atmospheric electricity, cloud phenomena, atmospheric extremes, and sea state. In addition, the respective engineering design elements are discussed relative to terrestrial environment inputs that require consideration. Specific lessons learned that have contributed to the advancements made in the application and awareness of terrestrial environment inputs for aerospace engineering applications are presented.

  14. Abiogenic methanogenesis during experimental komatiite serpentinization: Implications for the evolution of the early Precambrian atmosphere

    E-print Network

    Manning, Craig

    Abiogenic methanogenesis during experimental komatiite serpentinization: Implications 2012 Editor: J. Fein Keywords: Abiotic methanogenesis Serpentinization Precambrian atmosphere Faint experiments on olivine serpentinization at the same conditions. Faster rates of methanogenesis in the natural

  15. Bolide impacts and the oxidation state of carbon in the Earth's early atmosphere

    Microsoft Academic Search

    James F. Kasting

    1990-01-01

    A one-dimensional photochemical model was used to examine the effect of bolide impacts on the oxidation state of Earth's primitive atmosphere. The impact rate should have been high prior to 3.8 Ga before present, based on evidence derived from the Moon. Impacts of comets or carbonaceous asteroids should have enhanced the atmospheric CO\\/CO2 ratio by bringing in CO ice and\\/or

  16. Cooperative research in terrestrial planetary geology and geophysics

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This final report for the period of July 1991 to August 1994 covered a variety of topics concerning the study of Earth and Mars. The Earth studies stressed the interpretation of the MAGSAT crustal magnetic anomalies in order to determine the geological structure, mineralogical composition, magnetic nature, and the historical background of submarine features, and also featured work in the area of terrestrial remote sensing. Mars research included the early evolution of the Martian atmosphere and hydrosphere and the investigations of the large Martian impact basins. Detailed summaries of the research is included, along with lists of the publications resulting from this research.

  17. The effects of zonal atmospheric currents on the spectra of rotating early-type stars

    NASA Technical Reports Server (NTRS)

    Cranmer, Steven R.; Collins, George W., II

    1993-01-01

    We suggest the existence of zonal currents in the atmospheres of rapidly rotating stars analogous to those found in planetary atmospheres. The zonal flow is assumed to be characterized by 'thin' atmospheric, nearly geostrophic flow which does not change the gravity darkening and stellar shape determined by the underlying uniformly rotating model. The contribution that such flows make to the continuum spectra of such stars is investigated. The additional rotationally induced Doppler displacement resulting from such zonal wind belts can distort the rotationally broadened stellar lines leading to significant departures from the line profiles predicted by the classical model of rotating stars. Our estimates of the zonal flow velocity stem from the assumption of a relation between it and the latitudinal wavenumber of the zonal velocity field. It is thus possible to create barotropic atmosphere models which, in turn, enable the modeling of the stellar spectrum including important spectral lines. In addition, the radiative transfer equations for the Stokes parameters I and Q are solved for the locally plane-parallel atmospheres so that the polarization structure of the radiation field is determined. We find that the presence of zonal wind belts leads to significant changes in the photospheric polarization from those characteristic of a uniformly rotating model.

  18. Thermal evolution of an early magma ocean in interaction with the atmosphere

    NASA Astrophysics Data System (ADS)

    Lebrun, T.; Massol, H.; Chassefiere, E.; Davaille, A. B.; Marcq, E.; Sarda, P.; Leblanc, F.; Brandeis, G.

    2012-12-01

    Thermal evolution of magma oceans produced by collision with giant impactors late in accretion is expected to depend on the composition and structure of the atmosphere through the greenhouse effect of CO2 and H2O released from the magma during its crystallization. In order to constrain the various cooling timescales of the system, we developed a 1D parameterized convection model of the thermal evolution of a magma ocean coupled with a 1D radiative-convective model of a primitive atmosphere. We conducted a parametric study and depicted the influence of various parameters such as the initial volatile inventories, the initial depth of the magma ocean or the radiogenic heat production rate on the cooling sequence. Our results show that the presence of a convective-radiative steam atmosphere has a strong influence on the duration of the magma ocean phase varying from a few thousand years without atmosphere to typically 1 Myr when a steam atmosphere is present. The time required for the formation of a water ocean is respectively 0.1 Myr, 1.5 Myr and 10 Myr for Mars, Earth and Venus. This time would be virtually infinite for an Earth-sized planet located closer than 0.66 AU from the Sun. Because for Mars and Earth, these times are definitely shorter than the average time between major impacts, successive water oceans could have developed on Earth and Mars during accretion, making easier the loss of their atmospheres by impact erosion. On the contrary, Venus could have remained in the magma ocean stage for most of its accretion.

  19. Carbon Dioxide Clouds at High Altitude in the Tropics and in an Early Dense Martian Atmosphere

    NASA Technical Reports Server (NTRS)

    Colaprete, Anthony; Toon, Owen B.

    2001-01-01

    We use a time dependent, microphysical cloud model to study the formation of carbon dioxide clouds in the Martian atmosphere. Laboratory studies by Glandor et al. show that high critical supersaturations are required for cloud particle nucleation and that surface kinetic growth is not limited. These conditions, which are similar to those for cirrus clouds on Earth, lead to the formation of carbon dioxide ice particles with radii greater than 500 micrometers and concentrations of less than 0.1 cm(exp -3) for typical atmospheric conditions. Within the current Martian atmosphere, CO2 cloud formation is possible at the poles during winter and at high altitudes in the tropics during periods of increased atmospheric dust loading. In both cases, temperature perturbations of several degrees below the CO2 saturation temperature are required to nucleate new cloud particles suggesting that dynamical processes are the most common initiators of carbon dioxide clouds rather than diabatic cooling. The microphysical cloud model, coupled to a two-stream radiative transfer model, is used to reexamine the impact of CO2 clouds on the surface temperature within a dense CO2 atmosphere. The formation of carbon dioxide clouds leads to a warmer surface than what would be expected for clear sky conditions. The amount of warming is sensitive to the presence of dust and water vapor in the atmosphere, both of which act to dampen cloud effects. The radiative warming associated with cloud formation, as well as latent heating, work to dissipate the clouds when present. Thus, clouds never last for periods much longer than several days, limiting their overall effectiveness for warming the surface. The time average cloud optical depth is approximately unity leading to a 5-10 K warming, depending on the surface pressure. However, the surface temperature does not rise about the freezing point of liquid water even for pressures as high as 5 bars, at a solar luminosity of 75% the current value.

  20. Atmospheres

    NASA Astrophysics Data System (ADS)

    Bott, June; Yin, Hongbin; Sridhar, Seetharaman

    2014-12-01

    When high Al containing Fe alloys such as TRIP steels are exposed to atmospheres that contain N2 during re-heating, sub-surface nitrides form and these can be detrimental to mechanical properties. Nitride precipitation can be controlled by minimizing the access of the gaseous atmosphere to the metal surface, which can be achieved by a rapid growth of a continuous and adherent surface scale. This investigation utilizes a Au-image furnace attached to a confocal scanning microscope to simulate the annealing temperature vs time while Fe-Al alloys (with Al contents varying from 1 to 8 wt pct) are exposed to a O2-N2 atm with 10-6 atm O2. The heating times of 1, 10, and 100 minutes to the isothermal temperature of 1558 K (1285 °C) were used. It was found that fewer sub-surface nitride precipitates formed when the heating time was lowered and when Al content in the samples was increased. In the 8 wt pct samples, no internal nitride precipitates were present regardless of heating time. In the 3 and 5 wt pct samples, internal nitride precipitates were nearly more or less absent at heating times less than 10 minutes. The decrease in internal precipitates was governed by the evolving structure of the external oxide-scale. At low heating rates and/or low Al contents, significant Fe-oxide patches formed and these appeared to allow for ingress of gaseous N2. For the slow heating rates, ingress could have happened during the longer time spent in lower temperatures where non-protective alumina was present. As Al content in the alloy was increased, the external scale was Al2O3 and/or FeAl2O4 and more continuous and consequently hindered the N2 from accessing the metal surface. Increasing the Al content in the alloy had the effect of promoting the outward diffusion of Al in the alloy and thereby assisting the formation of the continuous external layer of Al2O3 and/or FeAl2O4.

  1. The composition of the primitive atmosphere and the synthesis of organic compounds on the early Earth

    NASA Technical Reports Server (NTRS)

    Bada, J. L.; Miller, S. L.

    1985-01-01

    The generally accepted theory for the origin of life on the Earth requires that a large variety of organic compounds be present to form the first living organisms and to provide the energy sources for primitive life either directly or through various fermentation reactions. This can provide a strong constraint on discussions of the formation of the Earth and on the composition of the primitive atmosphere. In order for substantial amounts of organic compounds to have been present on the prebiological Earth, certain conditions must have existed. There is a large body of literature on the prebiotic synthesis of organic compounds in various postulated atmospheres. In this mixture of abiotically synthesized organic compounds, the amino acids are of special interest since they are utilized by modern organisms to synthesize structural materials and a large array of catalytic peptides.

  2. Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2

    E-print Network

    Kite, Edwin

    temperatures were probably below freezing4-6 , implying24 that exoplanet habitable-zone calculations is a benchmark for habitable-39 zone calculations for exoplanets15 . Contrary to early work2 , it is doubtful Geological and Planetary Sciences, Caltech.6 2 Earth and Space Sciences, University of California - Los

  3. Thermal evolution of an early magma ocean in interaction with the atmosphere

    NASA Astrophysics Data System (ADS)

    Lebrun, T.; Massol, H.; ChassefièRe, E.; Davaille, A.; Marcq, E.; Sarda, P.; Leblanc, F.; Brandeis, G.

    2013-06-01

    The thermal evolution of magma oceans produced by collision with giant impactors late in accretion is expected to depend on the composition and structure of the atmosphere through the greenhouse effect of CO2 and H2O released from the magma during its crystallization. In order to constrain the various cooling timescales of the system, we developed a 1-D parameterized convection model of a magma ocean coupled with a 1-D radiative-convective model of the atmosphere. We conducted a parametric study and described the influences of the initial volatile inventories, the initial depth of the magma ocean, and the Sun-planet distance. Our results suggest that a steam atmosphere delays the end of the magma ocean phase by typically 1 Myr. Water vapor condenses to an ocean after 0.1, 1.5, and 10 Myr for, respectively, Mars, Earth, and Venus. This time would be virtually infinite for an Earth-sized planet located at less than 0.66 AU from the Sun. Using a more accurate calculation of opacities, we show that Venus is much closer to this threshold distance than in previous models. So there are conditions such as no water ocean is formed on Venus. Moreover, for Mars and Earth, water ocean formation timescales are shorter than typical time gaps between major impacts. This implies that successive water oceans may have developed during accretion, making easier the loss of their atmospheres by impact erosion. On the other hand, Venus could have remained in the magma ocean stage for most of its accretion.

  4. Early Results from the Lunar Atmosphere and Dust Environment Explorer (LADEE)

    NASA Astrophysics Data System (ADS)

    Elphic, Richard C.; Hine, Butler; Delory, Gregory T.; Mahaffy, Paul; Benna, Mehdi; Horanyi, Mihaly; Colaprete, Anthony; Noble, Sarah

    2014-05-01

    On 6 September, 2013, a near-perfect launch of the first Minotaur V rocket success-fully carried NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) into a high-eccentricity geocentric orbit. After 30 days of phasing, LADEE arrived at the Moon on 6 October, 2013. LADEE's science objectives are twofold: (1) Determine the composition of the lunar atmosphere, investigate processes controlling its distribution and variability, including sources, sinks, and surface interactions; (2) Characterize the lunar exospheric dust environment, measure its spatial and temporal variability, and effects on the lunar atmosphere, if any. After a successful commissioning phase, the three science instruments have made systematic observations of the lunar dust and exospheric environment. These include initial observations of argon, neon and helium exospheres, and their diurnal variations; the lunar micrometeoroid impact ejecta cloud and its variations; spatial and temporal variations of the sodium exosphere; and the search for sunlight extinction caused by dust. LADEE also made observations of the effects of the Chang'e 3 landing on 14 December 2013.

  5. Early Results from the Lunar Atmosphere and Dust Environment Explorer (LADEE)

    NASA Technical Reports Server (NTRS)

    Elphic, R. C.; Hine, B.; Delory, G. T.; Mahaffy, Paul; Benna, Mehdi; Horanyi, Mihaly; Colaprete, Anthony; Noble, Sarah

    2014-01-01

    On 6 September, 2013, a near-perfect launch of the first Minotaur V rocket successfully carried NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) into a high-eccentricity geocentric orbit. After 30 days of phasing, LADEE arrived at the Moon on 6 October, 2013. LADEE's science objectives are twofold: (1) Determine the composition of the lunar atmosphere, investigate processes controlling its distribution and variability, including sources, sinks, and surface interactions; (2) Characterize the lunar exospheric dust environment, measure its spatial and temporal variability, and effects on the lunar atmosphere, if any. After a successful commissioning phase, the three science instruments have made systematic observations of the lunar dust and exospheric environment. These include initial observations of argon, neon and helium exospheres, and their diurnal variations; the lunar micrometeoroid impact ejecta cloud and its variations; spatial and temporal variations of the sodium exosphere; and the search for sunlight extinction caused by dust. LADEE also made observations of the effects of the Chang'e 3 landing on 14 December 2013.

  6. Climate control of terrestrial carbon exchange across biomes and continents

    Microsoft Academic Search

    Chuixiang Yi; Daniel Ricciuto; Runze Li; John Wolbeck; Xiyan Xu; Mats Nilsson; Luis Aires; John D. Albertson; Christof Ammann; M. Altaf Arain; Alessandro C. de Araujo; Marc Aubinet; Mika Aurela; Zoltán Barcza; Alan Barr; Paul Berbigier; Jason Beringer; Christian Bernhofer; Andrew T. Black; Paul V. Bolstad; Fred C. Bosveld; Mark S. J. Broadmeadow; Nina Buchmann; Sean P. Burns; Pierre Cellier; Jingming Chen; Jiquan Chen; Philippe Ciais; Robert Clement; Bruce D. Cook; Peter S. Curtis; D. Bryan Dail; Ebba Dellwik; Nicolas Delpierre; Ankur R. Desai; Sabina Dore; Danilo Dragoni; Bert G. Drake; Eric Dufrêne; Allison Dunn; Jan Elbers; Werner Eugster; Matthias Falk; Christian Feigenwinter; Lawrence B. Flanagan; Thomas Foken; John Frank; Juerg Fuhrer; Damiano Gianelle; Allen Goldstein; Mike Goulden; Andre Granier; Thomas Grünwald; Lianhong Gu; Haiqiang Guo; Albin Hammerle; Shijie Han; Niall P. Hanan; László Haszpra; Bernard Heinesch; Carole Helfter; Dimmie Hendriks; Lindsay B. Hutley; Andreas Ibrom; Cor Jacobs; Torbjörn Johansson; Marjan Jongen; Gabriel Katul; Gerard Kiely; Katja Klumpp; Alexander Knohl; Thomas Kolb; Werner L. Kutsch; Peter Lafleur; Tuomas Laurila; Ray Leuning; Anders Lindroth; Heping Liu; Benjamin Loubet; Giovanni Manca; Michal Marek; Hank A. Margolis; Timothy A. Martin; William J. Massman; Roser Matamala; Giorgio Matteucci; Harry McCaughey; Lutz Merbold; Tilden Meyers; Mirco Migliavacca; Franco Miglietta; Laurent Misson; Meelis Mölder; John Moncrieff; Russell K Monson; Leonardo Montagnani; Mario Montes-Helu; Eddy Moors; Christine Moureaux; Mukufute M Mukelabai; J William Munger; May Myklebust; Zoltán Nagy; Asko Noormets; Walter Oechel; Ram Oren; Stephen G Pallardy; Kyaw Tha Paw U; João S Pereira; Kim Pilegaard; Krisztina Pintér; Casimiro Pio; Gabriel Pita; Thomas L Powell; Serge Rambal; James T Randerson; Corinna Rebmann; Janne Rinne; Federica Rossi; Nigel Roulet; Ronald J Ryel; Jorgen Sagerfors; Nobuko Saigusa; María José Sanz; Giuseppe-Scarascia Mugnozza; Hans Peter Schmid; Guenther Seufert; Mario Siqueira; Jean-François Soussana; Gregory Starr; Mark A Sutton; John Tenhunen; Juha-Pekka Tuovinen; Riccardo Valentini; Christoph S Vogel; Jingxin Wang; Shaoqiang Wang; Weiguo Wang; Lisa R Welp; Xuefa Wen; Sonia Wharton; Matthew Wilkinson; Christopher A Williams; Georg Wohlfahrt; Susumu Yamamoto; Guirui Yu; Roberto Zampedri; Bin Zhao; Xinquan Zhao

    2010-01-01

    Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net

  7. Role of land atmosphere interactions in WCRP - overview of the terrestrial component of GEWEX and the observing networks and field campaigns

    Microsoft Academic Search

    P. Try

    2002-01-01

    The Global Energy and Water Cycle Experiment (GEWEX) of the World Climate Research Programme (WCRP) has been designed to observe and model the hydrologic cycle and energy fluxes in the atmosphere, at the land surface, and in the upper oceans. GEWEX is an integrated program of research, observations, and science activities ultimately leading to the prediction of global and regional

  8. PERGAMON Journal of Atmospheric and Solar!Terrestrial Physics 59 "0887# 05840694 S02535715:88:, ! see front matter 0888 Published by Elsevier Science Ltd[ All rights reserved

    E-print Network

    Bergen, Universitetet i

    \\ their spreading in the upper atmosphere and the return ~ux of the charged and neutral component of the hydrogen~ecting their sensitivity to several charge exchange processes[ Ã? 0888 Elsevier Science Ltd[ All rights reserved[ 0 rockets and satellites\\ and it is found that the protons are a persistent feature of the auroral

  9. Using observational data to evaluate global terrestrial

    E-print Network

    to model land-atmosphere carbon exchange #12;Terrestrial Biospheric Models Well-informed Carbon cycle #12;Models Well-informed Carbon cycle projections Input data Initial conditions Parameter values Atmosphere Coupled Land Models Coupled carbon-climate models disagree on the continued strength of the net

  10. Spherically symmetric, expanding, non-LTE model atmospheres for novae during their early stages

    NASA Technical Reports Server (NTRS)

    Hauschildt, P. H.; Wehrse, R.; Starrfield, S.; Shaviv, G.

    1992-01-01

    In the continuum and line-blanketed models presented here, nova atmospheres are characterized by a very slow decrease of density with increasing radius. This feature leads to very large geometrical extensions so that there are large temperature differences between the inner and outer parts of the line-forming regions. The theoretical spectra show a large IR excess and a small Balmer jump which may be either in absorption or in emission. For the parameters considered (effective temperature of about 10 exp 4 K, L = 2 x 10 exp 4 solar luminosities, outer boundary density of about 3 x 10 exp -15 g cm exp -3, mass-loss rate of 10 exp -5 solar masses/yr), most lines are in absorption. The effects of changes in the abundances of the heavy elements on the emergent spectra are discussed. The strong unidentified features observed in ultraviolet spectra of novae are found in actuality to be regions of transparency within the Fe 'forest'. Ultraviolet spectra obtained from the IUE archives are displayed, and spectral synthesis of these spectra is done using the theoretical atmospheres.

  11. Terrestrial carbon cycle responses to drought and climate stress: New insights using atmospheric observations of CO2 and delta13C

    NASA Astrophysics Data System (ADS)

    Alden, Caroline B.

    Atmospheric concentrations of carbon dioxide (CO2) continue to rise well into the second decade of the new millennium, in spite of broad-scale human understanding of the impacts of fossil fuel emissions on the earth's climate. Natural sinks for CO2 that are relevant on human time scales---the world's oceans and land biosphere---appear to have kept pace with emissions. The continuously increasing strength of the land biosphere sink for CO2 is surpassing expectations given our understanding of the CO2 fertilization and warming effects on the balance between photosynthesis and respiration, especially in the face of ongoing forest degradation. The climate and carbon cycle links between the atmosphere and land biosphere are not well understood, especially at regional (100 km to 10,000 km) scales. The climate modulating effects of changing plant stomatal conductance in response to temperature and water availability is a key area of uncertainty. Further, the differential response to climate change of C3 and C4 plant functional types is not well known at regional scales. This work outlines the development of a novel application of atmospheric observations of delta13C of CO2 to investigate the links between climate and water and carbon cycling and the integrated responses of C3 and C4 ecosystems to climate variables. A two-step Bayesian batch inversion for 3-hourly, 1x1º CO2 fluxes (step one), and for 3-hourly 1x1º delta13C of recently assimilated carbon (step two) is created here for the first time, and is used to investigate links between regional climate indicators and changes in delta13C of the biosphere. Results show that predictable responses of regional-scale, integrated plant discrimination to temperature, precipitation and relative humidity anomalies can be recovered from atmospheric signals. Model development, synthetic data simulations to test sensitivity, and results for the year 2010 are presented here. This dissertation also includes two other applications of atmospheric observations of CO2 and delta13C: 1) a state of the art atmospheric CO2 budgeting exercise to show that global net sinks for CO2 have steadily increased over the last 50 years, and 2) a global investigation of the mechanistic drivers of interannual variability in biosphere discrimination against delta13C.

  12. Earth and the Terrestrial

    E-print Network

    Walter, Frederick M.

    Earth and the Geology of the Terrestrial Planets (Bennett et al. Ch. 9) #12; Terrestrial planets Major Ideas In This Chapter #12;Terrestrial Planets (NASA) Compared to Jovian planets: ­ Smaller size or no moons ­ No rings #12;Planetary Surfaces and Interiors Terrestrial planets + Moon were similar when

  13. Assessing the impact of elevated atmospheric CO{sub 2} and climate change scenarios of two and three dimensional general circulation models on primary production and toatl carbon storage of global terrestrial ecosystems

    SciTech Connect

    Xiao, X.; Kicklighter, D.W.; Melillo, J.M. [Marine Biological Laboratory, Woods Hole, MA (United States)] [and others

    1995-09-01

    The Terrestrial Ecosystem Model (TEM version 4) was applied to simulate primary production and total carbon storage for two atmospheric CO{sub 2} concentrations (315ppm and 630ppm) and three climate scenarios (contemporary, 2-dimensional MIT L-O climate model and 3-dimensional GISS). For contemporary climate (Cramer & Leemans dataset) at 315ppm CO{sub 2}, global annual NPP was 47.9 Pg C.yr{sup {minus}1} and total carbon storage was 1658.2 Pg C. Under atmospheric CO{sub 2} concentration of 630ppm and projected double CO{sub 2} climate by the MIT L-O climate model, global annual NPP increased by 12%, and total carbon storage increased by 11%. Global annual NPP and total carbon storage under the GISS were about 1% to 2% higher than those under the MIT L-O model. The difference in annual NPP and total carbon storage between the GISS and MIT L-O models varied among the 18 biomes, in the range of 0% to 20%. The differences were greatest in the high latitude ecosystems.

  14. Fossil Worm Burrows Reveal Very Early Terrestrial Animal Activity and Shed Light on Trophic Resources after the End-Cretaceous Mass Extinction

    PubMed Central

    Chin, Karen; Pearson, Dean; Ekdale, A. A.

    2013-01-01

    The widespread mass extinctions at the end of the Cretaceous caused world-wide disruption of ecosystems, and faunal responses to the one-two punch of severe environmental perturbation and ecosystem collapse are still unclear. Here we report the discovery of in situ terrestrial fossil burrows from just above the impact-defined Cretaceous-Paleogene (K/Pg) boundary in southwestern North Dakota. The crisscrossing networks of horizontal burrows occur at the interface of a lignitic coal and silty sandstone, and reveal intense faunal activity within centimeters of the boundary clay. Estimated rates of sedimentation and coal formation suggest that the burrows were made less than ten thousand years after the end-Cretaceous impact. The burrow characteristics are most consistent with burrows of extant earthworms. Moreover, the burrowing and detritivorous habits of these annelids fit models that predict the trophic and sheltering lifestyles of terrestrial animals that survived the K/Pg extinction event. In turn, such detritus-eaters would have played a critical role in supporting secondary consumers. Thus, some of the carnivorous vertebrates that radiated after the K/Pg extinction may owe their evolutionary success to thriving populations of earthworms. PMID:23951041

  15. FINAL REPORT: A Study of the Abundance and 13C/12C Ratio of Atmospheric Carbon Dioxide to Advance the Scientific Understanding of Terrestrial Processes Regulating the GCC

    SciTech Connect

    Keeling, R. F.; Piper, S. C.

    2008-12-23

    The main objective of this project was to continue research to develop carbon cycle relationships related to the land biosphere based on remote measurements of atmospheric CO2 concentration and its isotopic composition. The project continued time-series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites. The program also included the development of methods for measuring radiocarbon content in the collected CO2 samples and carrying out radiocarbon measurements in collaboration with Tom Guilderson of Lawrence Berkeley National Laboratory (LLNL). The radiocarbon measurements can provide complementary information on carbon exchange rates with the land and oceans and emissions from fossil-fuel burning. Using models of varying complexity, the concentration and isotopic measurements were used to establish estimates of the spatial and temporal variations in the net CO2 exchange with the atmosphere, the storage of carbon in the land and oceans, and variable isotopic discrimination of land plants.

  16. Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse

    PubMed Central

    Vandenbroucke, Thijs R. A.; Armstrong, Howard A.; Williams, Mark; Paris, Florentin; Zalasiewicz, Jan A.; Sabbe, Koen; Nõlvak, Jaak; Challands, Thomas J.; Verniers, Jacques; Servais, Thomas

    2010-01-01

    Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22× PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan (“mixed layer”) marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55°–70° S to ?40° S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of ?8× PAL to ?5× PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction. PMID:20696937

  17. Statistical equilibrium calculations for silicon in early-type model stellar atmospheres

    NASA Technical Reports Server (NTRS)

    Kamp, L. W.

    1976-01-01

    Line profiles of 36 multiplets of silicon (Si) II, III, and IV were computed for a grid of model atmospheres covering the range from 15,000 to 35,000 K in effective temperature and 2.5 to 4.5 in log (gravity). The computations involved simultaneous solution of the steady-state statistical equilibrium equations for the populations and of the equation of radiative transfer in the lines. The variables were linearized, and successive corrections were computed until a minimal accuracy of 1/1000 in the line intensities was reached. The common assumption of local thermodynamic equilibrium (LTE) was dropped. The model atmospheres used also were computed by non-LTE methods. Some effects that were incorporated into the calculations were the depression of the continuum by free electrons, hydrogen and ionized helium line blocking, and auto-ionization and dielectronic recombination, which later were found to be insignificant. Use of radiation damping and detailed electron (quadratic Stark) damping constants had small but significant effects on the strong resonance lines of Si III and IV. For weak and intermediate-strength lines, large differences with respect to LTE computations, the results of which are also presented, were found in line shapes and strengths. For the strong lines the differences are generally small, except for the models at the hot, low-gravity extreme of our range. These computations should be useful in the interpretation of the spectra of stars in the spectral range B0-B5, luminosity classes III, IV, and V.

  18. Atmospheric aerosols as prebiotic chemical reactors Christopher M. Dobson*, G. Barney Ellison

    E-print Network

    Ellison, Barney

    by an inverted micelle model. The aerosol sizes with significant atmospheric lifetimes are the same as those transformations in the prebiotic world. We also suggest that aerosols could have been precursors to life, since it is generally agreed that the common ancestor of terrestrial life was a single-celled organism. The early steps

  19. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data

    USGS Publications Warehouse

    Hayes, Daniel J.; Turner, David P.; Stinson, Graham; McGuire, A. David; Wei, Yaxing; West, Tristram O.; Heath, Linda S.; de Jong, Bernardus; McConkey, Brian G.; Birdsey, Richard A.; Kurz, Werner A.; Jacobson, Andrew R.; Huntzinger, Deborah N.; Pan, Yude; Post, W. Mac; Cook, Robert B.

    2012-01-01

    We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000–2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a -327 ± 252 TgC yr-1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (-248 TgC yr-1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (-297 TgC yr-1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr-1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated to be a small net source (+18 TgC yr-1) due to land use change between 1993 and 2002. We compare these inventory-based estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is -511 TgC yr-1 and -931 TgC yr-1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional -239 TgC yr-1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.

  20. Terrestrial soil pH and MAAT records based on the MBT/CBT in the southern South China Sea: implications for the atmospheric CO2 evolution in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Dong, L.; Li, L.; Li, Q.; Zhang, C.

    2013-12-01

    Liang Dong1, Li Li1, Qianyu Li1,2, Chuanlun L. Zhang1,3 1State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China 2School of Earth and Environment Sciences, University of Adelaide, SA 5005, Australia 3Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA The methylation index of branched tetraethers (MBT) and/or the cyclization ratio of branched tetraethers (CBT) are derived from the branched glycerol dialkyl Glycerol tetraethers (GDGTs) of bacterial origin and are widely used to reconstruct the terrestrial soil pH and mean annual air temperature (MAAT); however, these proxies are less frequently used in the oceanic settings. Here we provide the first high resolution records of soil pH and MAAT since the last glacial maximum based on the sedimentary core of MD05-2896 in the southern South China Sea. The MAAT record exhibited typical glacial and interglacial cycles and was consistent with the winter insolation variation. The pH values were lower (6.4-7) in the glacial time and higher (7-8.4) in the interglacial time. Changes in soil pH allowed the evaluation of changes in soil CO2 based on the atmosphere-soil CO2 balance. The results imply that the lower winter MAAT variation with a lower winter atmospheric CO2 concentration might have resulted in a higher pH in the interglacial period. Our records provide a new insight into the evolution of atmospheric CO2 between glacial and interglacial cycles in East Asia. Key words: South China Sea, MBT/CBT, b-GDGTs, MAAT, pH

  1. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions and a new approach for estimating net ecosystem exchange from inventory-based data

    SciTech Connect

    Hayes, Daniel J [ORNL; Turner, David P [Oregon State University, Corvallis; Stinson, Graham [Pacific Forestry Centre, Canadian Forest Service; Mcguire, David [University of Alaska; Wei, Yaxing [ORNL; West, Tristram O. [Joint Global Change Research Institute, PNNL; Heath, Linda S. [USDA Forest Service; De Jong, Bernardus [ECOSUR; McConkey, Brian G. [Agriculture and Agri-Food Canada; Birdsey, Richard A. [U.S. Department of Agriculture Forest Service; Kurz, Werner [Canadian Forest Service; Jacobson, Andrew [NOAA ESRL and CIRES; Huntzinger, Deborah [University of Michigan; Pan, Yude [U.S. Department of Agriculture Forest Service; Post, Wilfred M [ORNL; Cook, Robert B [ORNL

    2012-01-01

    We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000 2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a 327 252 TgC yr1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (248 TgC yr1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (297 TgC yr1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated tobe a small net source (+18 TgC yr1) due to land use change between 1993 and 2002. We compare these inventorybased estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is 511 TgC yr1 and 931 TgC yr1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional 239 TgC yr1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.

  2. Anomalous Xenon in the Precambrian Nuclear Reactor in Okelobondo (Gabon): A Possible Connection to the Fission Component in the Terrestrial Atmosphere

    NASA Technical Reports Server (NTRS)

    Meshik, A. P.; Kehm, K.; Hohenberg, C. M.

    1999-01-01

    Some CFF-Xe (Chemically Fractionated Fission Xenon), whose isotopic composition is established by simultaneous decay and migration of radioactive fission products, is probably present in the Earth's lithosphere, a conclusion based on available Xe data from various crustal and mantle rocks . Our recent isotopic analysis of Xe in alumophosphate from zone 13 of Okelobondo (southern extension of Oklo), along with the independent estimation of the isotopic composition of atmospheric fission Xe , supports the hypothesis that CFF-Xe was produced on a planetary scale. Additional information is contained in the original extended abstract.

  3. XUV-exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets. Part II: hydrogen coronae and ion escape.

    PubMed

    Kislyakova, Kristina G; Lammer, Helmut; Holmström, Mats; Panchenko, Mykhaylo; Odert, Petra; Erkaev, Nikolai V; Leitzinger, Martin; Khodachenko, Maxim L; Kulikov, Yuri N; Güdel, Manuel; Hanslmeier, Arnold

    2013-11-01

    We studied the interactions between the stellar wind plasma flow of a typical M star, such as GJ 436, and the hydrogen-rich upper atmosphere of an Earth-like planet and a "super-Earth" with a radius of 2 R(Earth) and a mass of 10 M(Earth), located within the habitable zone at ?0.24?AU. We investigated the formation of extended atomic hydrogen coronae under the influences of the stellar XUV flux (soft X-rays and EUV), stellar wind density and velocity, shape of a planetary obstacle (e.g., magnetosphere, ionopause), and the loss of planetary pickup ions on the evolution of hydrogen-dominated upper atmospheres. Stellar XUV fluxes that are 1, 10, 50, and 100 times higher compared to that of the present-day Sun were considered, and the formation of high-energy neutral hydrogen clouds around the planets due to the charge-exchange reaction under various stellar conditions was modeled. Charge-exchange between stellar wind protons with planetary hydrogen atoms, and photoionization, lead to the production of initially cold ions of planetary origin. We found that the ion production rates for the studied planets can vary over a wide range, from ?1.0×10²? s?¹ to ?5.3×10³? s?¹, depending on the stellar wind conditions and the assumed XUV exposure of the upper atmosphere. Our findings indicate that most likely the majority of these planetary ions are picked up by the stellar wind and lost from the planet. Finally, we estimated the long-time nonthermal ion pickup escape for the studied planets and compared them with the thermal escape. According to our estimates, nonthermal escape of picked-up ionized hydrogen atoms over a planet's lifetime within the habitable zone of an M dwarf varies between ?0.4 Earth ocean equivalent amounts of hydrogen (EO(H)) to <3 EO(H) and usually is several times smaller in comparison to the thermal atmospheric escape rates. PMID:24283926

  4. Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

    NASA Astrophysics Data System (ADS)

    Pérot, K.; Urban, J.; Murtagh, D. P.

    2014-08-01

    The middle atmosphere was affected by an exceptionally strong midwinter stratospheric sudden warming (SSW) during the Arctic winter 2012/2013. These unusual meteorological conditions led to a breakdown of the polar vortex, followed by the reformation of a strong upper stratospheric vortex associated with particularly efficient descent of air. Measurements by the submillimetre radiometer (SMR), on board the Odin satellite, show that very large amounts of nitric oxide (NO), produced by energetic particle precipitation (EPP) in the mesosphere/lower thermosphere (MLT), could thus enter the polar stratosphere in early 2013. The mechanism referring to the downward transport of EPP-generated NOx during winter is generally called the EPP indirect effect. SMR observed up to 20 times more NO in the upper stratosphere than the average NO measured at the same latitude, pressure and time during three previous winters where no mixing between mesospheric and stratospheric air was noticeable. This event turned out to be the strongest in the aeronomy-only period of SMR (2007-present). Our study is based on a comparison with the Arctic winter 2008/2009, when a similar situation was observed. This outstanding situation is the result of the combination of a relatively high geomagnetic activity and an unusually high dynamical activity, which makes this case a prime example to study the EPP impacts on the atmospheric composition.

  5. TERENO (Terrestrial Environmental Observatories): Establishment of a alpine observatory for long term observations of the impact of global change factors on biosphere-hydrosphere-atmosphere interactions

    NASA Astrophysics Data System (ADS)

    Kiese, R.; Papen, H.; Kunstmann, H.; Marx, A.; Butterbach-Bahl, K.; Schmid, H. P.

    2009-04-01

    Long term observations are an indispensable pre-requisite to improve our knowledge of the complex biosphere-hydrosphere-atmosphere (BHA)-interactions and to detect and analyze the impact of Global Change parameters on these interactions as well as to develop, improve and validate BHA model systems. FZK IMK-IFU will establish a Climate-Feedback Observatory at which the effects of predicted future changes in temperature and precipitation amount/distribution within the pre-alpine region on the complex BHA interactions will be studied applying a long term in-situ simulation experiment. For this a lysimeter network will be realized in which soil monoliths are transplanted along the existing natural gradient in temperature and precipitation within the alpine region. Details of this experimental approach will be presented. The central objectives of the scientific work performed are: Characterization and quantification of changes of the (i) coupled C-/N-cycles and C-/N-storage, (ii) biosphere-atmosphere exchange (trace gases/energy flux/albedo), (iii) vegetation and microbial biodiversity and of the temporal dynamics of matter turnover and exchange coupled to this change in biodiversity, (iv) seapage water quality/quantity

  6. Solar-terrestrial models and application software

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter

    1990-01-01

    The empirical models related to solar-terrestrial sciences are listed and described which are available in the form of computer programs. Also included are programs that use one or more of these models for application specific purposes. The entries are grouped according to the region of the solar-terrestrial environment to which they belong and according to the parameter which they describe. Regions considered include the ionosphere, atmosphere, magnetosphere, planets, interplanetary space, and heliosphere. Also provided is the information on the accessibility for solar-terrestrial models to specify the magnetic and solar activity conditions.

  7. Early deglacial Atlantic overturning decline and its role in atmospheric CO2 rise inferred from carbon isotopes (?13C)

    NASA Astrophysics Data System (ADS)

    Schmittner, A.; Lund, D. C.

    2015-02-01

    The reason for the initial rise in atmospheric CO2 during the last deglaciation remains unknown. Most recent hypotheses invoke Southern Hemisphere processes such as shifts in midlatitude westerly winds. Coeval changes in the Atlantic meridional overturning circulation (AMOC) are poorly quantified, and their relation to the CO2 increase is not understood. Here we compare simulations from a global, coupled climate-biogeochemistry model that includes a detailed representation of stable carbon isotopes (?13C) with a synthesis of high-resolution ?13C reconstructions from deep-sea sediments and ice core data. In response to a prolonged AMOC shutdown initialized from a preindustrial state, modeled ?13C of dissolved inorganic carbon (?13CDIC) decreases in most of the surface ocean and the subsurface Atlantic, with largest amplitudes (more than 1.5‰) in the intermediate-depth North Atlantic. It increases in the intermediate and abyssal South Atlantic, as well as in the subsurface Southern, Indian, and Pacific oceans. The modeled pattern is similar and highly correlated with the available foraminiferal ?13C reconstructions spanning from the late Last Glacial Maximum (LGM, ~19.5-18.5 ka BP) to the late Heinrich stadial event 1 (HS1, ~16.5-15.5 ka BP), but the model overestimates ?13CDIC reductions in the North Atlantic. Possible reasons for the model-sediment-data differences are discussed. Changes in remineralized ?13CDIC dominate the total ?13CDIC variations in the model but preformed contributions are not negligible. Simulated changes in atmospheric CO2 and its isotopic composition (?13CCO2) agree well with ice core data. Modeled effects of AMOC-induced wind changes on the carbon and isotope cycles are small, suggesting that Southern Hemisphere westerly wind effects may have been less important for the global carbon cycle response during HS1 than previously thought. Our results indicate that during the early deglaciation the AMOC decreased for several thousand years. We propose that the observed early deglacial rise in atmospheric CO2 and the decrease in ?13CCO2 may have been dominated by an AMOC-induced decline of the ocean's biologically sequestered carbon storage.

  8. Transient climate change and net ecosystem production of the terrestrial biosphere

    E-print Network

    Xiao, Xiangming.; Melillo, Jerry M.; Kicklighter, David W.; McGuire, A. David.; Prinn, Ronald G.; Wang, Chien.; Stone, Peter H.; Sokolov, Andrei P.

    The Terrestrial Ecosystem Model (TEM version 4.1) is applied to assess the sensitivity of net ecosystem production (NEP) of the terrestrial biosphere to transient changes in atmospheric CO2 concentration and climate in the ...

  9. Spaceborne Microwave Remote Sensing of Seasonal Freeze-Thaw Processes in the Terrestrial High Latitudes: Relationships with Land-Atmosphere CO2 exchange

    NASA Technical Reports Server (NTRS)

    McDonald, Kyle C.; Kimball, John S.; Zhao, Maosheng; Njoku, Eni; Zimmermann, Reiner; Running, Steven W.

    2004-01-01

    Landscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These relatively abrupt transitions represent the closest analog to a biospheric and hydrologic on/off switch existing in nature, affecting surface meteorological conditions, ecological trace gas dynamics, energy exchange and hydrologic activity profoundly. We utilize time series satellite-borne microwave remote sensing measurements from the Special Sensor Microwave Imager (SSM/I) to examine spatial and temporal variability in seasonal freeze/thaw cycles for the pan-Arctic basin and Alaska. Regional measurements of spring thaw timing are derived using daily brightness temperature measurements from the 19 GHz, horizontally polarized channel, separately for overpasses with 6 AM and 6 PM equatorial crossing times. Spatial and temporal patterns in regional freeze/thaw dynamics show distinct differences between North America and Eurasia, and boreal forest and Arctic tundra biomes. Annual anomalies in the timing of thawing in spring also correspond closely to seasonal atmospheric CO2 concentration anomalies derived from NOAA CMDL arctic and subarctic monitoring stations. Classification differences between AM and PM overpass data average approximately 5 days for the region, though both appear to be effective surrogates for monitoring annual growing seasons at high latitudes.

  10. Accretion and differentiation of the terrestrial planets with implications for the compositions of early-formed Solar System bodies and accretion

    E-print Network

    Nimmo, Francis

    of early-formed Solar System bodies and accretion of water D.C. Rubie a, , S.A. Jacobson a,b , A Science Institute, 1700 E. Ft. Lowell, Suite 106, Tucson, AZ 85719, USA d Dept. of Earth, Planetary that non-volatile ele- ments are present in Solar System (CI) relative abundances in all bodies

  11. Terrestrial Environment (Climatic) Criteria Handbook For Use in Aerospace Vehicle Development

    NASA Technical Reports Server (NTRS)

    Johnson, Dale; Vaughan, William W.

    2004-01-01

    An update of the NASA 'Terrestrial Environment (Climatic) Criteria Handbook for Use in Aerospace Vehicle Development' (NASA-HDBK-1001) is currently in the final process of completion for release in late-2004 or early 2005. The current version of the Handbook was approved by the NASA Chief Engineer in 2000 as a NASA Preferred Technical Standard. However, it was based on natural environment criteria developed mostly in the early 1990's. Therefore, a task was approved to completely update the Handbook in order to reflect the current state-of-the-art in the various terrestrial environmental climatic criteria areas. The technical areas include: Winds, atmospheric constituents, thermodynamic parameters/models/extremes, humidity, electricity, precipitation/fog/icing, cloud phenomena/cover, diffusion/toxic release, severe weather/tornado/hurricane, solar/thermal radiation, geologic hazards, and sea state. A summary of this extensive update will be presented along with some key examples of the new contents. Earlier versions of this publication have been extensively used by the aerospace community, especially program managers and design engineers for required natural terrestrial environment inputs to use in mission planning, development studies and trades, plus by those concerned with terrestrial environment descriptions for the major test ranges within the United States.

  12. Photochemistry in planetary atmospheres

    Microsoft Academic Search

    J. S. Levine; T. E. Graedel

    1981-01-01

    Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes

  13. Origin of the Ocean on the Earth: Early Evolution of Water D/H in a Hydrogen-rich Atmosphere

    E-print Network

    Hidenori Genda; Masahiro Ikoma

    2007-09-13

    The origin of the Earth's ocean has been discussed on the basis of deuterium/hydrogen ratios (D/H) of several sources of water in the solar system. The average D/H of carbonaceous chondrites (CC's) is known to be close to the current D/H of the Earth's ocean, while those of comets and the solar nebula are larger by about a factor of two and smaller by about a factor of seven, respectively, than that of the Earth's ocean. Thus, the main source of the Earth's ocean has been thought to be CC's or adequate mixing of comets and the solar nebula. However, those conclusions are correct only if D/H of water on the Earth has remained unchanged for the past 4.5 Gyr. In this paper, we investigate evolution of D/H in the ocean in the case that the early Earth had a hydrogen-rich atmosphere, the existence of which is predicted by recent theories of planet formation no matter whether the nebula remains or not. Then we show that D/H in the ocean increases by a factor of 2-9, which is caused by the mass fractionation during atmospheric hydrogen loss, followed by deuterium exchange between hydrogen gas and water vapor during ocean formation. This result suggests that the apparent similarity in D/H of water between CC's and the current Earth's ocean does not necessarily support the CC's origin of water and that the apparent discrepancy in D/H is not a good reason for excluding the nebular origin of water.

  14. Sensitivity of Holocene atmospheric CO2 and the modern carbon budget to early human land use: analyses with a process-based model

    Microsoft Academic Search

    B. D. Stocker; K. Strassmann; F. Joos

    2011-01-01

    A Dynamic Global Vegetation model coupled to a simplified Earth system model is used to simulate the impact of anthropogenic land cover changes (ALCC) on Holocene atmospheric CO2 and the contemporary carbon cycle. The model results suggest that early agricultural activities cannot explain the mid to late Holocene CO2 rise of 20 ppm measured on ice cores and that proposed

  15. Early Paleogene Arctic terrestrial ecosystems affected by the change of polar hydrology under global warming: Implications for modern climate change at high latitudes

    Microsoft Academic Search

    Qin Leng; Gaytha A. Langlois; Hong Yang

    2010-01-01

    Our understanding of both the role and impact of Arctic environmental changes under the current global warming climate is\\u000a rather limited despite efforts of improved monitoring and wider assessment through remote sensing technology. Changes of Arctic\\u000a ecosystems under early Paleogene warming climate provide an analogue to evaluate long-term responses of Arctic environmental\\u000a alteration to global warming. This study reviews Arctic

  16. Nanophase Iron Oxides as an Ultraviolet Sunscreen for Ancient Photosynthetic Microbes: A Possible Link Between Early Organisms, Banded-Iron Formations, and the Oxygenation of the Atmosphere

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Rothschild, Lynn J.; Rothschild, Lynn J.; Rogoff, Dana A.

    2006-01-01

    We propose that nanophase iron oxide-bearing materials provided important niches for ancient photosynthetic microbes on the early Earth that ultimately led to the oxygenation of the Earth s atmosphere and the formation of iron oxide deposits. Atmospheric oxygen and ozone attenuate UV radiation on the Earth today providing substantial protection for photosynthetic organisms. With ultraviolet radiation fluxes likely to have been even higher on the early Earth than today, accessing solar radiation was particularly risky for early organisms. Yet, we know that photosynthesis arose then and played a critical role in subsequent evolution. Of primary importance was protection at approx.250-290 nm, where peak nucleic acid (approx.260 nm) and protein (approx.280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal UV radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Further, they were available in early environments, and are synthesized by many organisms. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the photosynthetic organisms, Euglena sp. and Chlumydomonus reinhardtii, we propose a scenario where photosynthesis, and ultimately the oxygenation of the atmosphere, depended on the protection of early microbes by nanophase ferric oxides/oxyhydroxides. The results of this study are also applicable to other potentially habitable iron-bearing planetary bodies because of the evolutionary pressure to utilize solar radiation when available as an energy source.

  17. Climate change effects on environment (marine, atmospheric and terrestrial) and human perception in an Italian Region (Marche) and the nearby northern Adriatic Sea.

    NASA Astrophysics Data System (ADS)

    Appiotti, F.; Krzelj, M.; Marincioni, F.; Russo, A.

    2012-04-01

    An integrated analysis of recent climate change, including atmosphere, sea and land, as well as some of the impacts on society, has been conducted on the Marche Region in central Italy and the northern portion of the Adriatic Sea. The Marche Region is one of the 20 administrative divisions of Italy, located at a latitude approximately 43° North, with a total surface area of 9,366 km2 and 1,565,000 residents. The northern Adriatic Sea is the northernmost area of the Mediterranean Sea, and it has peculiar relevance for several aspects (environment, tourism, fisheries, economy). The collected environmental data included meteorological stations (daily maximum and minimum air temperature, daily precipitation), oceanographic stations (sea temperature, salinity, dissolved oxygen, nutrient salts concentration, chlorophyll) and river flows, over the last 50 years. The collected social data include 800 questionnaires and interviews carried out on selected samples of residents, decision-makers and emergency managers. These questionnaires and interviews aimed at highlighting the perception of climate change risks. The trend analysis of air temperature and precipitation data detailed an overall temperature increase in all seasons and rainfall decreases in Winter, Spring and Summer with Autumn increases, influencing river flow changes. Marine data showed a relevant warming of the water column in the period after 1990 in comparison with the previous period, particularly in the cold season. Surface salinity increased in Spring and Summer and strongly decreased in Autumn and Winter (according with the precipitation and river flow changes). These last mentioned changes, combined with anthropogenic effects, also influenced the marine ecosystems, with changes of nutrient salts, chlorophyll and dissolved oxygen. Changes in nutrient discharge from rivers influenced the average marine chlorophyll concentration reduction and the consequent average reduction of warm season hypoxic conditions. Indeed, all these changes influence several other aspects of the North Adriatic marine environment, such as coastal erosion, ecosystems, biological productivity, mucilage phenomena, harmful algal blooms, etc.. These impacts in the coastal areas are also evident inland. For example, the analysis of agro-meteorological extreme indices (aridity index, potential water deficit) suggests negative impacts in terms of soil deterioration and agricultural productivity, particularly evident in the area close to the coast. Finally, the analysis of social data revealed awareness among local residents of these impacts and associated risks connected to climate change. Yet, this awareness does not appear translated into long term adaptation plans. Apparently, the inability to define shared collective strategies is the result of a feeble sense of individual and institutional responsibility about climate matters, and ineffective information exchange among citizens, public administrators and the scientific community.

  18. Breccia pipes in the Karoo Basin, South Africa, as conduits for metamorphic gases to the Early Jurassic atmosphere

    NASA Astrophysics Data System (ADS)

    Silkoset, Petter; Svensen, Henrik; Planke, Sverre

    2014-05-01

    The Toarcian (Early Jurassic) event was manifested by globally elevated temperatures and anoxic ocean conditions that particularly affected shallow marine taxa. The event coincided with the emplacement of the vast Karoo-Ferrar Large Igneous Province. Among the suggestions for trigger mechanisms for the climatic perturbation is metamorphic methane generation from black shale around the sills in the Karoo Basin, South Africa. The sill emplacement provides a mechanism for voluminous in-situ production and emission of greenhouse gases, and establishes a distinct link between basin-trapped and atmospheric carbon. In the lower stratigraphic levels of the Karoo Basin, black shales are metamorphosed around sills and the sediments are cut by a large number of pipe structures with metamorphic haloes. The pipes are vertical, cylindrical structures that contain brecciated and baked sediments with variable input of magmatic material. Here, we present borehole, petrographic, geochemical and field data from breccia pipes and contact aureoles based on field campaigns over a number of years (2004-2014). The metamorphism around the pipes show equivalent metamorphic grade as the sediments around nearby sills, suggesting a more prominent phreatomagmatic component than previously thought. The stratigraphic position of pipes and the breccia characteristics strengthens the hypothesis of a key role in the Toarcian carbon isotope excursion.

  19. Terrestrial Planet Geophysics

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.

    2008-12-01

    Terrestrial planet geophysics beyond our home sphere had its start arguably in the early 1960s, with Keith Runcorn contending that the second-degree shape of the Moon is due to convection and Mariner 2 flying past Venus and detecting no planetary magnetic field. Within a decade, in situ surface geophysical measurements were carried out on the Moon with the Apollo program, portions of the lunar magnetic and gravity fields were mapped, and Jack Lorell and his colleagues at JPL were producing spherical harmonic gravity field models for Mars using tracking data from Mariner 9, the first spacecraft to orbit another planet. Moreover, Mariner 10 discovered a planetary magnetic field at Mercury, and a young Sean Solomon was using geological evidence of surface contraction to constrain the thermal evolution of the innermost planet. In situ geophysical experiments (such as seismic networks) were essentially never carried out after Apollo, although they were sometimes planned just beyond the believability horizon in planetary mission queues. Over the last three decades, the discipline of terrestrial planet geophysics has matured, making the most out of orbital magnetic and gravity field data, altimetric measurements of surface topography, and the integration of geochemical information. Powerful constraints are provided by tectonic and volcanic information gleaned from surface images, and the engagement of geologists in geophysical exercises is actually quite useful. Accompanying these endeavors, modeling techniques, largely adopted from the Earth Science community, have become increasingly sophisticated and have been greatly enhanced by the dramatic increase in computing power over the last two decades. The future looks bright with exciting new data sets emerging from the MESSENGER mission to Mercury, the promise of the GRAIL gravity mission to the Moon, and the re-emergence of Venus as a worthy target for exploration. Who knows? With the unflagging optimism and persistence of a few diehards, we may eventually have a seismic and heat flow network on Mars.

  20. Estimating precipitation on early Mars using a radiative-convective model of the atmosphere and comparison with inferred runoff from geomorphology

    NASA Astrophysics Data System (ADS)

    von Paris, P.; Petau, A.; Grenfell, J. L.; Hauber, E.; Breuer, D.; Jaumann, R.; Rauer, H.; Tirsch, D.

    2015-01-01

    We compare estimates of atmospheric precipitation during the Martian Noachian-Hesperian boundary 3.8 Gyr ago as calculated in a radiative-convective column model of the atmosphere with runoff values estimated from a geomorphological analysis of dendritic valley network discharge rates. In the atmospheric model, we assume CO2-H2O-N2 atmospheres with surface pressures varying from 20 mb to 3 bar with input solar luminosity reduced to 75% the modern value. Results from the valley network analysis are of the order of a few mm d-1 liquid water precipitation (1.5-10.6 mm d-1, with a median of 3.1 mm d-1). Atmospheric model results are much lower, from about 0.001-1 mm d-1 of snowfall (depending on CO2 partial pressure). Hence, the atmospheric model predicts a significantly lower amount of precipitated water than estimated from the geomorphological analysis. Furthermore, global mean surface temperatures are below freezing, i.e. runoff is most likely not directly linked to precipitation. Therefore, our results strongly favor a cold early Mars with episodic snowmelt as a source for runoff. Our approach is challenged by mostly unconstrained parameters, e.g. greenhouse gas abundance, global meteorology (for example, clouds) and planetary parameters such as obliquity - which affect the atmospheric result - as well as by inherent problems in estimating discharge and runoff on ancient Mars, such as a lack of knowledge on infiltration and evaporation rates and on flooding timescales, which affect the geomorphological data. Nevertheless, our work represents a first step in combining and interpreting quantitative tools applied in early Mars atmospheric and geomorphological studies.

  1. Identification of Terrestrial Reflectance From Remote Sensing

    NASA Technical Reports Server (NTRS)

    Alter-Gartenberg, Rachel; Nolf, Scott R.; Stacy, Kathryn (Technical Monitor)

    2000-01-01

    Correcting for atmospheric effects is an essential part of surface-reflectance recovery from radiance measurements. Model-based atmospheric correction techniques enable an accurate identification and classification of terrestrial reflectances from multi-spectral imagery. Successful and efficient removal of atmospheric effects from remote-sensing data is a key factor in the success of Earth observation missions. This report assesses the performance, robustness and sensitivity of two atmospheric-correction and reflectance-recovery techniques as part of an end-to-end simulation of hyper-spectral acquisition, identification and classification.

  2. Impact of geoengineering schemes on the terrestrial biosphere

    Microsoft Academic Search

    B. Govindasamy; S. Thompson; P. B. Duffy; K. Caldeira; C. Delire

    2002-01-01

    Climate stabilization via ``Geoengineering'' schemes seek to mitigate climate change due to increased greenhouse gases by compensating reduction in solar radiation incident on earth's surface. In this paper, we address the impact of these climate stabilization schemes on terrestrial biosphere using equilibrium simulations from a coupled atmosphere-terrestrial biosphere model. Climate stabilization would tend to limit changes in vegetation distribution brought

  3. Impact of geoengineering schemes on the terrestrial biosphere

    Microsoft Academic Search

    B. Govindasamy; S. Thompson; P. B. Duffy; K. Caldeira; C. Delire

    2002-01-01

    Climate stabilization via “Geoengineering” schemes seek to mitigate climate change due to increased greenhouse gases by compensating reduction in solar radiation incident on earth's surface. In this paper, we address the impact of these climate stabilization schemes on terrestrial biosphere using equilibrium simulations from a coupled atmosphere-terrestrial biosphere model. Climate stabilization would tend to limit changes in vegetation distribution brought

  4. Experimental investigation of anaerobic nitrogen fixation rates with varying pressure, temperature and metal concentration with application to the atmospheric evolution of early Earth and Mars.

    NASA Astrophysics Data System (ADS)

    Gupta, Prateek

    2012-07-01

    The atmosphere of the early Earth is thought to have been significantly different than the modern composition of 21% O2 and 78% N2, yet the planet has been clearly established as hosting microbial life as far back as 3.8 billion years ago. As such, constraining the atmospheric composition of the early Earth is fundamental to establishing a database of habitable atmospheric compositions. A similar argument can be made for the planet Mars, where nitrates have been hypothesized to exist in the subsurface. During the early period on Mars when liquid water was likely more abundant, life may have developed to take advantage of available nitrates and a biologically-driven Martian nitrogen cycle could have evolved. Early Earth atmospheric composition has been investigated numerically, but only recently has the common assumption of a pN2 different than modern been investigated. Nonetheless, these latest attempts fail to take into account a key atmospheric parameter: life. On modern Earth, nitrogen is cycled vigorously by biology. The nitrogen cycle likely operated on the early Earth, but probably differed in the metabolic processes responsible, dominantly due to the lack of abundant oxygen which stabilizes oxidized forms of N that drive de-nitrification today. Recent advances in evolutionary genomics suggest that microbial pathways that are relatively uncommon today (i.e. vanadium and iron-based nitrogen fixation) probably played important roles in the early N cycle. We quantitatively investigate in the laboratory the effects of variable pressure, temperature and metal concentration on the rates of anoxic nitrogen fixation, as possible inputs for future models investigating atmospheric evolution, and better understand the evolution of the nitrogen cycle on Earth. A common anaerobic methanogenic archaeal species with i) a fully sequenced genome, ii) all three nitrogenases (molybdenum, vanadium and iron-based) and iii) the ability to be genetically manipulated will be used as a model species. This species will be genetically modified to create knock-out mutants lacking one or more nitrogenase genes. These mutants will be used in variable pressure, temperature and metal-concentration experiments. Nitrogen fixation rate and nitrogenase gene expression will be measured using isotope dilution and quantitative polymerase chain reaction, respectively.

  5. An atmosphere-ocean GCM modelling study of the climate response to changing Arctic seaways in the early Cenozoic.

    NASA Astrophysics Data System (ADS)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2008-12-01

    The report of fossil Azolla (a freshwater aquatic fern) in sediments from the Lomonosov Ridge suggests low salinity conditions occurred in the Arctic Ocean in the early Eocene. Restricted passages between the Arctic Ocean and the surrounding oceans are hypothesized to have caused this Arctic freshening. We investigate this scenario using a water-isotope enabled atmosphere-ocean general circulation model with Eocene boundary conditions including 4xCO2, 7xCH4, altered bathymetry and topography, and an estimated distribution of Eocene vegetational types. In one experiment, oceanic exchange between the Arctic Ocean and other ocean basins was restricted to two shallow (~250 m) seaways, one in the North Atlantic, the Greenland-Norwegian seaway, and the second connecting the Arctic Ocean with the Tethys Ocean, the Turgai Straits. In the restricted configuration, the Greenland-Norwegian seaway was closed and exchange through the Turgai Straits was limited to a depth of ~60 m. The simulations suggest that the severe restriction of Arctic seaways in the early Eocene may have been sufficient to freshen Arctic Ocean surface waters, conducive to Azolla blooms. When exchange with the Arctic Ocean is limited, salinities in the upper several hundred meters of the water column decrease by ~10 psu. In some regions, surface salinity is within 2-3 psu of the reported maximum modern conditions tolerated by Azolla (~5 psu). In the restricted scenario, salt is stored preferentially in the North Atlantic and Tethys oceans, resulting in enhanced meridional overturning, increased poleward heat transport in the North Atlantic western boundary current, and warming of surface and intermediate waters in the North Atlantic by several degrees. Increased sensible and latent heat fluxes from the North Atlantic Ocean, combined with a reduction in cloud albedo, also lead to an increase in surface air temperature of over much of North America, Greenland and Eurasia. Our work is consistent with previous findings on the potential influence of Arctic gateways on ocean overturning and also suggests that Northern Hemisphere climate, particularly in the North Atlantic, was very sensitive to changes in Arctic seaways. This result is of particular significance when considered in the context of the Paleocene Eocene Thermal Maximum (PETM). Volcanic activity prior to the PETM may have been responsible for the formation of a sub-aerial barrier in the North Atlantic, and consequently may have driven warming of intermediate waters sufficient to destabilize methane clathrates. Evidence for freshening of Arctic ocean waters prior to the PETM would support this hypothesis.

  6. Terrestrial gamma ray flashes and lightning discharges

    Microsoft Academic Search

    M. B. Cohen; R. K. Said; D. M. Smith; L. I. Lopez

    2006-01-01

    Analysis of ELF\\/VLF broadband data from Palmer Station, Antarctica indicates that 76% Terrestrial Gamma-ray Flashes (TGFs) detected on the RHESSI spacecraft occur in association with lightning-generated radio atmospherics arriving from near the footprint of RHESSI and within a few ms of the TGF. The remaining TGFs are not associated with any radio atmospheric, thus by implication CG lightning. The peak

  7. Detecting the Dusty Debris of Terrestrial Planet Formation

    E-print Network

    Scott J Kenyon; Benjamin C Bromley

    2004-01-16

    We use a multiannulus accretion code to investigate debris disks in the terrestrial zone, at 0.7-1.3 AU around a 1 solar mass star. Terrestrial planet formation produces a bright dusty ring of debris with a lifetime of at least 1 Myr. The early phases of terrestrial planet formation are observable with current facilities; the late stages require more advanced instruments with adaptive optics.

  8. Terrestrial Environment (Climatic) Criteria Handbook for Use in Aerospace Vehicle Development

    NASA Technical Reports Server (NTRS)

    Johnson, Dale L.; Vaughan, William W.

    2004-01-01

    Aerospace Meteorology provides the identification of that aspect of meteorology that is concerned with the definition and modeling of atmospheric parameters for use in aerospace vehicle development, mission planning and operational capability assessments. One of the principal sources of this information is the NASA-HDBK-1001 "Terrestrial Environment (Climatic) Criteria Handbook for Use in Aerospace Vehicle Development'. This handbook was approved by the NASA Chief Engineer in 2000 as a NASA Preferred Technical Standard . Its technical contents were based on natural environment statistics/models and criteria developed mostly in the early 1990's. A task was approved to completely update the handbook to reflect the current state-of-the-art in the various terrestrial environment climatic areas.

  9. Responses of early, mid and late season apple cultivars to postharvest application of 1-methylcyclopropene (1-MCP) under air and controlled atmosphere storage conditions

    Microsoft Academic Search

    Christopher B Watkins; Jacqueline F Nock; Bruce D Whitaker

    2000-01-01

    The potential for commercial application of 1-methylcyclopropene (1-MCP) to maintain quality of ‘McIntosh’, ‘Empire’, ‘Delicious’ and ‘Law Rome’ apples under air and controlled atmosphere (CA) storage conditions was investigated. These cultivars represent early, mid and late season apples with ripening rates ranging from fast to slow. 1-MCP gas concentrations used were 0.5, 1 and 2 ?l l?1, generated from measured

  10. Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002-2003

    Microsoft Academic Search

    W. Knorr; N. Gobron; M. Scholze; T. Kaminski; R. Schnur; B. Pinty

    2007-01-01

    Understanding the carbon dynamics of the terrestrial biosphere during climate fluctuations is a prerequisite for any reliable modeling of the climate-carbon cycle feedback. We drive a terrestrial vegetation model with observed climate data to show that most of the fluctuations in atmospheric CO2 are consistent with the modeled shift in the balance between carbon uptake by terrestrial plants and carbon

  11. Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002–2003

    Microsoft Academic Search

    W. Knorr; N. Gobron; M. Scholze; T. Kaminski; R. Schnur; B. Pinty

    2007-01-01

    Understanding the carbon dynamics of the terrestrial biosphere during climate fluctuations is a prerequisite for any reliable modeling of the climate-carbon cycle feedback. We drive a terrestrial vegetation model with observed climate data to show that most of the fluctuations in atmospheric CO2 are consistent with the modeled shift in the balance between carbon uptake by terrestrial plants and carbon

  12. A climate induced transition in the tectonic style of a terrestrial planet A. Lenardic a,

    E-print Network

    Jellinek, Mark

    A climate induced transition in the tectonic style of a terrestrial planet A. Lenardic a, , A that an increase in the surface temperature of a terrestrial planet due to an enhanced concentration of atmospheric links the interior dynamics of a terrestrial planet to its climatic evolution. A complementary link

  13. Terrestrial dominance of organic matter in north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, G.; Pace, M. L.; Cole, J. J.

    2012-12-01

    Aquatic ecosystems are hotspots of decomposition and a source of carbon dioxide to the atmosphere that is globally significant. Carbon exported from land (allochthonous) also supplements the carbon fixed by photosynthesis in aquatic ecosystems (autochthonous), contributing to the organic matter (OM) that supports aquatic consumers. Although the presence of terrestrial compounds in aquatic OM is well known, the contribution of terrestrial versus aquatic sources to the composition of OM has been quantified for only a handful of systems. Here we use stable isotopes of hydrogen and carbon to demonstrate that the terrestrial contribution to particulate organic matter (POM) is as large or larger (mean=54.6% terrestrial) than the algal contribution in 39 lakes of the northern highlands region of Wisconsin and Michigan. Further, the largest carbon pool, dissolved organic matter (DOM), is strongly dominated by allochthonous material (mean for the same set of lakes approximately 100% terrestrial). Among lakes, increases in terrestrial contribution to POM are significantly correlated with more acidic pH. Extrapolating this relationship using a survey of pH in 1692 lakes in the region reveals that, with the exception of eutrophic lakes, most of the OM in lakes is of terrestrial origin. These results are consistent with the growing evidence that terrestrial OM may support many lake food webs, and that lakes are significant conduits for returning degraded terrestrial carbon to the atmosphere.

  14. Atmospheric escape, redox evolution, and planetary habitability

    NASA Astrophysics Data System (ADS)

    Catling, D. C.; Zahnle, K. J.

    2011-12-01

    Through the greenhouse effect, the presence and composition of an atmosphere is critical for defining a (conventional) circumstellar habitable zone in terms of planetary surface temperatures suitable for liquid water. Lack of knowledge of planetary atmospheres is likely to frustrate attempts to say with any certainty whether detected terrestrial-sized exoplanets may or may not be habitable. Perhaps an underappreciated role in such considerations is the evolutionary effect of atmospheric escape for determining atmospheric composition or whether an atmosphere exists in the first place. Whether atmospheres exist at all on planets is demonstrably connected to the effect of integrated atmospheric escape. When we observe our own Solar System and transiting exoplanets, the existence of an atmosphere is clearly delineated by a relative vulnerability to thermal escape and impact erosion. The prevalence of thermal escape as a key evolutionary determinant for the presence of planetary atmosphere is shown by a relationship between the relative solar (or stellar) heating and the escape velocity. Those bodies with too much stellar heating and too smaller escape velocity end up devoid of atmospheres. Impact erosion is evident in the relationship between impact velocity and escape velocity. Escape due to impacts is particularly important for understanding the large differences in the atmospheres of giant planet moons, such as Ganymede versus Titan. It is also significant for Mars-sized planets. The oxidation state of atmospheres is important for some theories of the origin of life (where an early reducing atmosphere is helpful for organic synthesis) and the evolution of advanced life (where free molecular oxygen is the best source of high energy metabolism). Surfaces on some relatively small planets and moons are observed to have evolved to an oxidized state, which theory and observation can explain through atmospheric escape. There are several examples in the Solar System where a net escape of hydrogen relative to heavier oxygen is the generally accepted explanation for the present oxidation state: Venus and Mars amongst the planets, and Ganymede, Europa, and Rhea amongst bodies with extremely tenuous atmospheres. We also argue that hydrogen escape was the key factor for oxidizing the Earth and facilitating the increase of photosynthetically-produced oxygen in the Proterozoic atmosphere. Our view about the primacy of hydrogen escape with regard to the Earth's atmospheric oxygenation is perhaps less widely accepted. However, it was inevitable that hydrogen escaped from Earth's early anoxic atmosphere at a significant rate. The result was a very big integrated oxidation consistent with what is observed in the Earth's crust in addition to some export to the mantle. In conclusion, a better understanding of atmospheric escape processes appears critical for understanding the suitability of planets for harboring life from simple to advanced forms.

  15. Abiotic Nitrogen Fixation on Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Summers, David P.; Khare, B.; Basa, R. C. B.; Rodoni, D.

    2009-09-01

    The abiotic fixation of nitrogen is critical to planetary evolution and the potential for life on terrestrial planets. A non-biological source of nitrogen, in a biochemically accessible form, is necessary for the origin and early evolution of life. Loss of nitrogen can result in atmospheric pressures too low for liquid water and will impact planetary habitability and hydrological processes. Shock heating of a non-reducing atmosphere produces NO and this has been well studied. Our understanding of the subsequent reactions was, in the past, theoretical. It was postulated that NO was photochemically converted to HNO which then, in surface waters, reacts to form nitrate and nitrite. This chemistry, including reactions in both the gas phase and the liquid phase, has now been studied experimentally. Our work has observed that there are multiple pathways for the fixation. One pathway observed is consistent with the theoretically predicted route via the formation of HNO. Interestingly, this pathway is coupled to photochemical formation of formaldehyde from CO through the formation of HCO. In the presence of liquid water, this pathway leads to the formation of nitrate and nitrite. In the presence of water vapor, but no liquid water, HNO appears to mostly dimerize to form N2O. A second pathway involves the formation of NO2 from CO2 and NO. This pathway becomes more dominant without water, but the reaction of NO2 with even adsorbed water can lead to the formation of nitric acid. Finally, with FeS suspended in liquid water, the direct reduction of NO to ammonia is observed. This last pathway represents the most efficient way to reduced nitrogen, with product yields well above 20% (nitrite/nitrate, from the first two pathways can also be reduced to ammonia thought the overall efficiency suffers). We wish to thank the NASA Astrobiology Institute for support.

  16. Terrestrial Analogs to Mars

    Microsoft Academic Search

    T. G. Farr; S. Arcone; R. W. Arvidson; V. Baker; N. G. Barlow; D. Beaty; M. S. Bell; D. D. Blankenship; N. Bridges; G. Briggs; M. Bulmer; F. Carsey; S. M. Clifford; R. A. Craddock; P. W. Dickerson; N. Duxbury; G. L. Galford; J. Garvin; J. Grant; J. R. Green; T. K. P. Gregg; E. Guinness; V. L. Hansen; M. H. Hecht; J. Holt; A. Howard; L. P. Keszthelyi; P. Lee; P. D. Lanagan; R. C. F. Lentz; D. W. Leverington; L. Marinangeli; J. E. Moersch; P. A. Morris-Smith; P. Mouginis-Mark; G. R. Olhoeft; G. G. Ori; P. Paillou; J. F. Reilly II; J. W. Rice Jr.; C. A. Robinson; M. Sheridan; K. Snook; B. J. Thomson; K. Watson; K. Williams; K. Yoshikawa

    2002-01-01

    It is well recognized that interpretations of Mars must begin with the Earth as a reference. The most successful comparisons have focused on understanding geologic processes on the Earth well enough to extrapolate to Mars' environment. Several facets of terrestrial analog studies have been pursued and are continuing. These studies include field workshops, characterization of terrestrial analog sites, instrument tests,

  17. TERRESTRIAL ECOSYSTEM SIMULATOR

    EPA Science Inventory

    The Terrestrial Habitats Project at the Western Ecology Division (Corvallis, OR) is developing tools and databases to meet the needs of Program Office clients for assessing risks to wildlife and terrestrial ecosystems. Because habitat is a dynamic condition in real-world environm...

  18. The Boreal Ecosystem-Atmosphere Study (BOREAS): An Overview and Early Results from the 1994 Field Year

    Microsoft Academic Search

    Piers Sellers; Forrest Hall; K. Jon Ranson; Hank Margolis; Bob Kelly; Dennis Baldocchi; Gerry den Hartog; Josef Cihlar; Michael G. Ryan; Barry Goodison; Patrick Crill; Dennis Lettenmaier; Diane E. Wickland

    1995-01-01

    The Boreal Ecosystem Atmosphere Study (BOREAS) is large-scale international field experiment that has the goal of improving our understanding of the exchanges of radiative energy, heat water, CO2, and trace gases between the boreal forest and the lower atmosphere. An important objective of BORES is collect the data needed to improve computer simulation models of the processes controlling these exchanges

  19. A consistent picture of early hydrodynamic escape of Venus atmosphere explaining present Ne and Ar isotopic ratios and low oxygen atmospheric content

    Microsoft Academic Search

    Cédric Gillmann; Eric Chassefière; Philippe Lognonné

    2009-01-01

    A time dependent model of hydrogen hydrodynamic escape powered by solar EUV flux and solar wind, and accounting for oxygen frictional escape, has been implemented in primitive Venus conditions. The model is constrained by the present 20Ne\\/22Ne and 36Ar\\/38Ar ratios in Venus atmosphere. It suggests that the net total amount of water delivered to the planet during accretion (?10–100 Myr) is

  20. Modern Microbial Ecosystems are a Key to Understanding Our Biosphere's Early Evolution and its Contributions To The Atmosphere and Rock Record

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The survival of our early biosphere depended upon efficient coordination anion- diverse microbial populations. Microbial mats exhibit a 3.46-billion-year fossil record, thus they are the oldest known ecosystems. Photosynthetic microbial mats were key because, today, sunlight powers more than 99 percent of global primary productivity. Thus photosynthetic ecosystems have affected the atmosphere profoundly and have created the most pervasive, easily-detected fossils. Photosynthetic biospheres elsewhere will be most detectible via telescopes or spacecraft. As a part of the Astrobiology Institute, our Ames Microbial Ecosystems group examines the roles played by ecological processes in the early evolution of our biosphere, as recorded in geologic fossils and in the macromolecules of living cells: (1) We are defining the microbial mat microenvironment, which was an important milieu for early evolution. (2) We are comparing mats in contrasting environments to discern strategies of adaptation and diversification, traits that were key for long-term survival. (3) We have selected sites that mimic key environmental attributes of early Earth and thereby focus upon evolutionary adaptations to long-term changes in the global environment. (4) Our studies of gas exchange contribute to better estimates of biogenic gases in Earth's early atmosphere. This group therefore directly addresses the question: How have the Earth and its biosphere influenced each other over time Our studies strengthen the systematics for interpreting the microbial fossil record and thereby enhance astrobiological studies of martian samples. Our models of biogenic gas emissions will enhance models of atmospheres that might be detected on inhabited extrasolar planets. This work therefore also addresses the question: How can other biospheres be recogniZed" Our choice of field sites helps us explore Earth's evolving early environment. For example, modern mats that occupy thermal springs and certain freshwater environments experience conditions such as low O2 and sulfate and high inorganic carbon and sulfide levels that resemble those of ancient marine environments. Later in history, both biologically-induced carbonate precipitation and the trapping and binding of suspended grains of carbonate became a dominant mechanism for carbonate deposition. Modern marine carbonate platforms and alkaline offer good examples of microbiologically-induced calcification. Both marine platforms and solar salterns illustrate microbially-driven trapping and binding. We are also exploring the effects of water composition upon the exchange of biogenic gases with the atmosphere.

  1. Monte Carlo simulation of the terrestrial hydrogen exosphere

    SciTech Connect

    Hodges, R.R. Jr. [Univ. of Texas, Dallas, TX (United States)

    1994-12-01

    Methods for Monte Carlo simulation of planetary exospheres have evolved from early work on the lunar atmosphere, where the regolith surface provides a well defined exobase. A major limitation of the successor simulations of the exospheres of Earth and Venus is the use of an exobase surface as an artifice to separate the collisional processes of the thermosphere from a collisionles exosphere. In this paper a new generalized approach to exosphere simulation is described, wherein the exobase is replaced by a barometric depletion of the major constitents of the thermosphere. Exospheric atoms in the thermosphere-exosphere transition region, and in the outer exosphere as well, travel in ballistic trajectories that are interrupted by collisons with the background gas, and by charge exchange interactions with ionospheric particles. The modified simulator has been applied to the terrestrial hydrogen exosphere problem, using velocity dependent differential cross sections to provide statistically correct collisional scattering in H-O and H-H(+) interactions. Global models are presented for both solstice and equinox over the effective solar cycle range of the F{sub 10.7} index (80 to 230). Simulation results show significant differences with previous terrestrial exosphere models, as well as with the H distributions of the MSIS-86 thermosphere model.

  2. Mammalian faunal response to the Early Eocene Climatic Optimum (~53.5-48.5 mya) and a new terrestrial record of the associated carbon isotope excursion from Raven Ridge in the Uinta Basin, Colorado-Utah

    NASA Astrophysics Data System (ADS)

    Dutchak, A. R.

    2010-12-01

    Raven Ridge straddles the Colorado-Utah border on the northeastern edge of the Uinta Basin and consists of intertonguing units of the fluvial Colton and lacustrine Green River Formations. Fossil vertebrate localities along the ridge have produced a diverse mammalian fauna comprising 64 genera in 34 families. Included are the index taxa Smilodectes, Omomys, Heptodon, and Lambdotherium which suggest an age range of mid-Wasatchian (Wa5, ~53.5mya) through mid Bridgerian (Br2, ~48.5mya) for the Raven Ridge fauna. Others have shown that this time interval coincides with the onset, peak, and decline of the Early Eocene Climatic Optimum (EECO), an extended interval of globally warm temperatures following the Paleocene-Eocene Thermal Maximum (PETM) that is coincident with a large negative carbon excursion. The Raven Ridge fauna provides an excellent opportunity to investigate the effects of a lengthy interval of global warmth on mammalian diversity and ecosystem structure. To study changes in the mammalian fauna that occurred during the EECO, it was necessary to constrain the onset, peak, and decline of the EECO at Raven Ridge through chemostratigraphic correlation with established marine isotope curves. This was accomplished by analysis of approximately 300 sediment samples for Total Organic Carbon (TOC) content. TOC has been used successfully in the Bighorn Basin to identify the stratigraphic occurrence of the Carbon Isotope Excursion (CIE) associated with the PETM, which has roughly the same amplitude as the negative excursion associated with the EECO. The Raven Ridge TOC data show a large negative carbon excursion that starts during the Wa6 biochron, peaks during the Wa7 biochron, and is followed by a positive excursion near the Wa-Br boundary. This terrestrial ?13C pattern is consistent with results seen in established marine isotope curves across the EECO interval. The minimum ?13C value of the negative excursion is -29.67‰, which is comparable to the Bighorn CIE values, and the maximum ?13C value of the positive excursion is -20.51‰. The Raven Ridge mammalian fauna shows a gradual increase in generic diversity from Wa5, when the fauna was dominated by terrestrially-adapted ischyromyid rodents and the condylarth Hyopsodus, through the Wa6 and Wa7 biochrons when arboreal primates including microsyopids, omomyids, and adapids, increased in diversity and relative abundance. These results are consistent with diversity trends seen in meta-analyses of North American mammalian diversity during the EECO. The diversity increase at Raven Ridge is mirrored by a change in ranked familial abundance from a skewed distribution during Wa5 to more even distributions during Wa6-Br1 time, an interval which is shown by previous studies in Wyoming to coincide with a significant increase in floral diversity. One interpretation of these patterns is that there was a floral shift associated with the EECO in central North America, with the relatively open habitats of the mid-Wasatchian being replaced by more densely forested canopy systems, with increased niche space allowing for diversification and increased abundance of arboreal taxa, during the late Wasatchian and early Bridgerian.

  3. Where did Terrestrial Life Begin?

    Microsoft Academic Search

    J. W. Gregory

    1922-01-01

    IN reference to Mr. Dines's letter in NATURE of February 16, if the diurnal variations in temperature and humidity on a mountain summit in the early earth would have been smaller than at sea-level, my objection to Dr. Macfie's theory would certainly not hold. But Mr. Dines remarks that, assuming some stratification of the atmosphere, the stirring up of the

  4. Where did Terrestrial Life Begin?

    Microsoft Academic Search

    J. W. Gregory

    1922-01-01

    DR. MACFIE'S suggestion that life originated on the mountain summits is new, and entitled to careful consideration. If the early earth, when its atmosphere was laden with carbon dioxide and steam, had been windless, then the mountain summits would have stood like islands above a sea of hot mist, and they would have been the only situations possible for the

  5. The Role of Giant Planets in Terrestrial Planet Formation

    NASA Astrophysics Data System (ADS)

    Levison, H. F.; Duncan, M. J.; Agnor, C. B.

    2000-05-01

    The dynamical structure of the outer planetary system has played a critical role in determining the sizes, numbers, and habitability of the terrestrial planets. In 1996, Wetherill showed that the presence of Jupiter affects the masses of planets in the Habitable Zone of the Sun. In addition, in our solar system the giant planets control the dynamics of most of Earth's impactors, which consist of objects from the asteroid belt, the Kuiper belt, the scattered comet disk, and the Oort cloud. At early times, these impactors may have been responsible for supplying the Earth with a significant fraction of its water, organics, and atmospheric volatiles. At later times, they are responsible for causing at least some mass extinctions. Recent observations have demonstrated that giant planet configurations can show startling variations from system to system. (Although the searches for extra-solar planets have yet to reveal anything about what `typical systems' are like due to strong observational biases.) The question therefore naturally arises: What kind of outer planetary systems can support habitable terrestrial planets? The Exobiology Program is funding us to undertake the first comprehensive study of the coupling between outer solar system architectures and inner solar system habitability. The first stage of this program was to construct a wide range of outer planetary systems. The results of this work can be found at www.boulder.swri.edu/ hal/diversity.html. Here we present a preliminary report on simulations of the formation of terrestrial planets in two of these synthetic outer planetary systems. The first contains 5 planets; three of which lie between 3.7 and 11AU and have a combined mass of 2600 Earth-masses ( 8 Jupiter-masses). The second system contains 7 planets between 4 and 35AU; the largest of which is only 26 Earth-masses ( 1.5 Neptune masses).

  6. Extreme Terrestrial Gamma ray Events

    NASA Astrophysics Data System (ADS)

    Manchanda, R. K.; Kamble, Nilima

    2012-07-01

    Terrestrial gamma ray flashes were first discovered by the Compton GRO observatory and such event have been observed later on-board Rhessi satellite and more recently by the Fermi and Agile missions. These events are believed to be associated with the thunderstorm activity in the lower atmosphere. When observed from the satellite instruments, the observed time structure. Shows short milliseconds bursts probably due to lightning discharges , however an other type of long bursts with a duration of a few seconds to a few minutes have been observed only in the lower atmosphere. Such behaviour is natural as the upward moving photons go through a large atmospheric depth several 100 gms which will affect both the time structure and the spectral nature as the thunderstorms normally originate only in the lower troposphere just above the convective boundary layer. We report the observations of extreme terrestrial gamma ray events with time duration ~150-250 min observed during the thunderstorm activity in Hyderabad South, India. At 17.3o lat. and 78.6o long., Hyderabad is located in the convergence zone with high level of thunderstorm activity during the monsoon period. Spectral data suggest a continuum flux of the gamma ray from 100 keV to 10 MeV for hours. Temporal characteristics studied with time resolution of 100 microsec do not show any excess power density at any frequency. The data suggest that unlike gamma ray flashes which are generated just during the lightening flash, large electric field disturbances during long thunderstorm activity may lead to large flux of accelerated particles, which emit continuum gamma rays flux.

  7. Sources of Terrestrial Volatiles

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Dones, L.

    1998-01-01

    Atmospheres are found enveloping those planets and satellites best able to hold them. The obvious conclusion is that volatile escape must have played nearly as great a role as volatile supply. A consequence of this view is that volatile supplies were probably much greater than the atmospheres that remain. The likeliest candidates are sources associated with the main events of planetary accretion itself such as volatile-rich planetesimals, or direct gravitational capture of nebular gases. Late asteroidal or cometary volatile-rich veneers are attractive, but they present quantitative difficulties. Comets in particular are inadequate, because the associated mass of stray comets that would have been scattered to the Oort Cloud or beyond is excessive. This difficulty applies to Uranus-Neptune planetesimals as well as to a putative massive early Kuiper Belt. Another potential problem with comets is that the D/H ratio in the three comets for which this has been measured is about twice that of Earth's oceans. Objects falling from a much augmented ancient asteroid belt remain a viable option, but timing is an issue: Can the depopulation of the asteroid belt be delayed long enough that it makes sense to talk of asteroids as a late veneer? Early accretion of asteroids as objects scattered into the maw of infant Earth makes more sense. Another appealing candidate population of volatile-rich objects for the inner solar system would be scattered planetesimals associated with the accretion of Jupiter, for two reasons: (1) Before there was Jupiter, there was no object in the solar system capable of expelling comets efficiently, and (2) the cross section of the inner solar system to stray objects was Greater when there were m many planetesimals.

  8. Possible climates on terrestrial exoplanets.

    PubMed

    Forget, F; Leconte, J

    2014-04-28

    What kind of environment may exist on terrestrial planets around other stars? In spite of the lack of direct observations, it may not be premature to speculate on exoplanetary climates, for instance, to optimize future telescopic observations or to assess the probability of habitable worlds. To begin with, climate primarily depends on (i) the atmospheric composition and the volatile inventory; (ii) the incident stellar flux; and (iii) the tidal evolution of the planetary spin, which can notably lock a planet with a permanent night side. The atmospheric composition and mass depends on complex processes, which are difficult to model: origins of volatiles, atmospheric escape, geochemistry, photochemistry, etc. We discuss physical constraints, which can help us to speculate on the possible type of atmosphere, depending on the planet size, its final distance for its star and the star type. Assuming that the atmosphere is known, the possible climates can be explored using global climate models analogous to the ones developed to simulate the Earth as well as the other telluric atmospheres in the solar system. Our experience with Mars, Titan and Venus suggests that realistic climate simulators can be developed by combining components, such as a 'dynamical core', a radiative transfer solver, a parametrization of subgrid-scale turbulence and convection, a thermal ground model and a volatile phase change code. On this basis, we can aspire to build reliable climate predictors for exoplanets. However, whatever the accuracy of the models, predicting the actual climate regime on a specific planet will remain challenging because climate systems are affected by strong positive feedbacks. They can drive planets with very similar forcing and volatile inventory to completely different states. For instance, the coupling among temperature, volatile phase changes and radiative properties results in instabilities, such as runaway glaciations and runaway greenhouse effect. PMID:24664919

  9. The Early Origins of Terrestrial C4

    E-print Network

    indicate that the timing of C4 geographical expan- sion was not globally synchronous, and thus point toward under specific climatic condi- tions. Hence, the origin and subsequent geographical expansion of the C4 plants likely reflects a record of climate change. Multiple pa- leoatmospheric pCO2 proxies indicate

  10. Terrestrial dominance of organic matter in north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, Grace M.; Pace, Michael L.; Cole, Jonathan J.

    2013-01-01

    Aquatic ecosystems are hotspots of decomposition and sources of carbon dioxide to the atmosphere that are globally significant. Carbon exported from land (allochthonous) also supplements the carbon fixed by photosynthesis in aquatic ecosystems (autochthonous), contributing to the organic matter (OM) that supports aquatic consumers. Although the presence of terrestrial compounds in aquatic OM is well known, the contribution of terrestrial versus aquatic sources to the composition of OM has been quantified for only a handful of systems. Here we use stable isotopes of hydrogen and carbon to demonstrate that the terrestrial contribution (?Terr) to particulate organic matter (POM) is as large or larger (mean = 54.6% terrestrial) than the algal contribution in 39 lakes of the northern highlands region of Wisconsin and Michigan. Further, the largest carbon pool, dissolved organic matter (DOM), is strongly dominated by allochthonous material (mean for the same set of lakes approximately 100% terrestrial). Among lakes, increases in terrestrial contribution to POM are significantly correlated with more acidic pH. Extrapolating this relationship using a survey of pH in 1692 lakes in the region reveals that, with the exception of eutrophic lakes, most of the OM in lakes is of terrestrial origin. These results are consistent with the growing evidence that lakes are significant conduits for returning degraded terrestrial carbon to the atmosphere.

  11. Responses of terrestrial aridity to global warming

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Feng, Song

    2014-07-01

    The dryness of terrestrial climate can be measured by the ratio of annual precipitation (P) to potential evapotranspiration (PET), where the latter represents the evaporative demand of the atmosphere, which depends on the surface air temperature, relative humidity, wind speed, and available energy. This study examines how the terrestrial mean aridity responds to global warming in terms of P/PET using the Coupled Model Intercomparison Project phase 5 transient CO2 increase to 2 × CO2 simulations. We show that the (percentage) increase (rate) in P averaged over land is ~1.7%/°C ocean mean surface air temperature increase, while the increase in PET is 5.3%/°C, leading to a decrease in P/PET (i.e., a drier terrestrial climate) by ~3.4%/°C. Noting a similar rate of percentage increase in P over land to that in evaporation (E) over ocean, we propose a framework for examining the change in P/PET, in which we compare the change in PET over land and E over ocean, both expressed using the Penman-Monteith formula. We show that a drier terrestrial climate is caused by (i) enhanced land warming relative to the ocean, (ii) a decrease in relative humidity over land but an increase over ocean, (iii) part of increase in net downward surface radiation going into the deep ocean, and (iv) different responses of PET over land and E over ocean for given changes in atmospheric conditions (largely associated with changes in temperatures). The relative contributions to the change in terrestrial mean aridity from these four factors are about 35%, 35%, 15%, and 15%, respectively. The slight slowdown of the surface wind over both land and ocean has little impact on the terrestrial mean aridity.

  12. Terrestrial Impact Structures

    NASA Astrophysics Data System (ADS)

    Grieve, R. A. F.

    Emphasis is placed on the nature of terrestrial impact structures, the criteria for their identification, and their contribution to constraining formational processes and cratering rate estimates. The relationship of large-scale impact to Earth history is also considered.

  13. Terrestrial photovoltaic measurements, 2

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The following major topics are discussed; (1) Terrestrial solar irradiance; (2) Solar simulation and reference cell calibration; and (3) Cell and array measurement procedures. Numerous related subtopics are also discussed within each major topic area.

  14. Primordial Terrestrial Xenon Revisited

    NASA Astrophysics Data System (ADS)

    Meshik, A. P.; Pravdivtseva, O. V.; Hohenberg, C. M.

    2014-09-01

    Xenon solar wind composition revealed by Genesis matches mathematically derived primordial terrestrial xenon with high precision, except for 136Xe and 134Xe. This can be explained by modification of fission yields in open systems.

  15. Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Smith, Andrew

    2004-01-01

    Integrating and testing the proposed Terrestrial Planet Finder imposes constraints on the design. Some of these will be discussed including the dimensions of existing test facilities, the effects of gravity, ambient vibrations and the size of GSE optics.

  16. Effects of an Early-Time Impact Generated Vapor Blast in the Martian Atmosphere: Formation of High-Latitude Pedestal Craters

    NASA Technical Reports Server (NTRS)

    Wrobel, K. E.; Schultz, P. H.; Crawford, D. A.

    2005-01-01

    Following impact, vapor expansion creates an intense airblast that interacts with the ambient atmosphere. The resulting hemi-spherical shock wave leaves a signature on the surface that is dependent on initial atmospheric and surface conditions. Here we propose that the formation of pedestal craters (craters surrounded by an erosion-resistant pedestal) may be a direct consequence of extreme winds and elevated temperatures generated by such an impact-induced atmospheric blast. Pedestal craters, first recognized in Mariner 9 data, are a unique feature on Mars and likely a signature of near-surface volatiles. They are found at high latitudes (small pedestals, Amazonian to Late Hesperian in age) and in thick equatorial mantling deposits (larger pedestals, early Hesperian to Noachian in age). Previously suggested mechanisms for pedestal crater formation (e.g., wind: ejecta curtain vortices or vapor blast; and ejecta dust: armoring) do not provide a complete picture. The clear evidence for near-surface volatiles at high latitudes requires a re-evaluation of these alternative models. The results presented here suggest that a combined atmospheric blast/thermal model provides a plausible formation hypothesis.

  17. Terrestrial and Extraterrestrial Fullerenes

    Microsoft Academic Search

    D. Heymann; L. W. Jenneskens; J. Jehli?ka; Carola Koper; E. J. Vlietstra

    2003-01-01

    This paper reviews reports of occurrences of fullerenes in circumstellar media, interstellar media, meteorites, interplanetary dust particles (IDPs), lunar rocks, hard terrestrial rocks from Shunga (Russia), Sudbury (Canada) and Mitov (Czech Republic), coal, terrestrial sediments from the Cretaceous?Tertiary?Boundary and Permian?Triassic?Boundary, fulgurite, ink sticks, dinosaur eggs, and a tree char. The occurrences are discussed in the context of known and postulated

  18. Predictability of the terrestrial carbon cycle.

    PubMed

    Luo, Yiqi; Keenan, Trevor F; Smith, Matthew

    2015-05-01

    Terrestrial ecosystems sequester roughly 30% of anthropogenic carbon emission. However this estimate has not been directly deduced from studies of terrestrial ecosystems themselves, but inferred from atmospheric and oceanic data. This raises a question: to what extent is the terrestrial carbon cycle intrinsically predictable? In this paper, we investigated fundamental properties of the terrestrial carbon cycle, examined its intrinsic predictability, and proposed a suite of future research directions to improve empirical understanding and model predictive ability. Specifically, we isolated endogenous internal processes of the terrestrial carbon cycle from exogenous forcing variables. The internal processes share five fundamental properties (i.e., compartmentalization, carbon input through photosynthesis, partitioning among pools, donor pool-dominant transfers, and the first-order decay) among all types of ecosystems on the Earth. The five properties together result in an emergent constraint on predictability of various carbon cycle components in response to five classes of exogenous forcing. Future observational and experimental research should be focused on those less predictive components while modeling research needs to improve model predictive ability for those highly predictive components. We argue that an understanding of predictability should provide guidance on future observational, experimental and modeling research. PMID:25327167

  19. Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems

    Microsoft Academic Search

    J. I. House; K. A. Hibbard; P. Bousquet; P. Ciais; P. Peylin; B. H. Braswell; M. J. Apps; D. Baker; A. Bondeau; J. Canadell; G. Churkina; W. Cramer; A. S. Denning; C. B. Field; P. Friedlingstein; C. Goodale; M. Heimann; R. A. Houghton; J. M. Melillo; B. Moore; D. Murdiyarso; I. Noble; S. W. Pacala; I. C. Prentice; M. R. Raupach; P. J. Rayner; R. J. Scholes; W. L. Steffen; C. Wirth; D. S. Schimel

    2001-01-01

    Knowledge of carbon exchange between the atmosphere, land and the oceans is important, given that the terrestrial and marine environments are currently absorbing about half of the carbon dioxide that is emitted by fossil-fuel combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic change, but its long-term nature remains uncertain. Here we provide an overview of

  20. Thermal evolution of an early magma ocean in interaction with the atmosphere: conditions for the condensation of a water ocean

    NASA Astrophysics Data System (ADS)

    Lebrun, Thomas; Massol, Helene; Chassefiere, Eric; Davaille, Anne; Marcq, Emmanuel; Sarda, Philippe; Leblanc, François; Brandeis, Geneviève

    2013-04-01

    The thermal evolution of magma oceans produced by collision with giant impactors late in planetary accretion is expected to depend on the composition and structure of the atmosphere through the greenhouse effect of CO2 and H2O released from the magma during its crystallization. In order to constrain the various cooling timescales of the system, we developed a 1D parameterized convection model of the thermal evolution of a magma ocean coupled with a 1D radiative-convective model of a primitive atmosphere. We conducted a parametric study to investigate the influence of the initial volatile inventories, the initial depth of the magma ocean and the radiogenic heat production rate on the cooling sequence. Our results show that the presence of a convective-radiative steam atmosphere has a strong influence on the duration of the magma ocean phase, which varies from a few thousand years without atmosphere to typically 1 Myr when a steam atmosphere is present. Moreover, the time required for the formation of a water ocean on the planet surface is respectively 0.1 Myr, 1.5 Myr and 10 Myr for Mars, Earth and Venus. This time would be virtually infinite for an Earth-sized planet located closer than 0.66 AU from the Sun. For Mars and the Earth, these times are definitely shorter than the average time between major impacts, so that successive water oceans could have developed during accretion, facilitating the loss of their atmospheres by impact erosion. On the contrary, Venus could have remained in the magma ocean stage for most of its accretion.

  1. The Laboratory for Terrestrial Physics

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Laboratory for Terrestrial Physics is dedicated to the advancement of knowledge in Earth and planetary science, by conducting innovative research using space technology. The Laboratory's mission and activities support the work and new initiatives at NASA's Goddard Space Flight Center (GSFC). The Laboratory's success contributes to the Earth Science Directorate as a national resource for studies of Earth from Space. The Laboratory is part of the Earth Science Directorate based at the GSFC in Greenbelt, MD. The Directorate itself is comprised of the Global Change Data Center (GCDC), the Space Data and Computing Division (SDCD), and four science Laboratories, including Laboratory for Terrestrial Physics, Laboratory for Atmospheres, and Laboratory for Hydrospheric Processes all in Greenbelt, MD. The fourth research organization, Goddard Institute for Space Studies (GISS), is in New York, NY. Relevant to NASA's Strategic Plan, the Laboratory ensures that all work undertaken and completed is within the vision of GSFC. The philosophy of the Laboratory is to balance the completion of near term goals, while building on the Laboratory's achievements as a foundation for the scientific challenges in the future.

  2. Thermal evolution of an early magma ocean in interaction with the atmosphere: conditions for the condensation of a

    E-print Network

    Brandeis, Geneviève

    -planet distance. Our results suggest that a steam atmosphere delays the end of the magma ocean phase by typically, Earth and Venus. This time would be virtually infinite for an Earth-sized planet located at less than 0.66 AU from the Sun. So there are conditions such as no water ocean is formed on Venus. Moreover

  3. Methane production in terrestrial arthropods.

    PubMed Central

    Hackstein, J H; Stumm, C K

    1994-01-01

    We have screened more than 110 representatives of the different taxa of terrestrial arthropods for methane production in order to obtain additional information about the origins of biogenic methane. Methanogenic bacteria occur in the hindguts of nearly all tropical representatives of millipedes (Diplopoda), cockroaches (Blattaria), termites (Isoptera), and scarab beetles (Scarabaeidae), while such methanogens are absent from 66 other arthropod species investigated. Three types of symbiosis were found: in the first type, the arthropod's hindgut is colonized by free methanogenic bacteria; in the second type, methanogens are closely associated with chitinous structures formed by the host's hindgut; the third type is mediated by intestinal anaerobic protists with intracellular methanogens. Such symbiotic associations are likely to be a characteristic property of the particular taxon. Since these taxa represent many families with thousands of species, the world populations of methane-producing arthropods constitute an enormous biomass. We show that arthropod symbionts can contribute substantially to atmospheric methane. Images PMID:8202505

  4. Effect of increasing CO2 on the terrestrial carbon cycle.

    PubMed

    Schimel, David; Stephens, Britton B; Fisher, Joshua B

    2015-01-13

    Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation. PMID:25548156

  5. Precursor Science for the Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Lawson, P. R. (Editor); Unwin, S. C. (Editor); Beichman, C. A. (Editor)

    2004-01-01

    This document outlines a path for the development of the field of extrasolar planet research, with a particular emphasis on the goals of the Terrestrial Planet Finder (TPF). Over the past decade, a new field of research has developed, the study of extrasolar planetary systems, driven by the discovery of massive planets around nearby stars. The planet count now stands at over 130. Are there Earth-like planets around nearby stars? Might any of those planets be conducive to the formation and maintenance of life? These arc the questions that TPF seeks to answer. TPF will be implemented as a suite of two space observatories, a 6-m class optical coronagraph, to be launched around 20 14, and a formation flying mid-infrared interferometer, to be launched sometime prior to 2020. These facilities will survey up to 165 or more nearby stars and detect planets like Earth should they be present in the 'habitable zone' around each star. With observations over a broad wavelength range, TPF will provide a robust determination of the atmospheric composition of planets to assess habitability and the presence of life. At this early stage of TPF's development, precursor observational and theoretical programs are essential to help define the mission, to aid our understanding of the planets that TPF could discover, and to characterize the stars that TPF will eventually study. This document is necessarily broad in scope because the significance of individual discoveries is greatly enhanced when viewed in thc context of the field as a whole. This document has the ambitious goal of taking us from our limited knowledge today, in 2004, to the era of TPF observations in the middle of the next decade. We must use the intervening years wisely. This document will be reviewed annually and updated as needed. The most recent edition is available online at http://tpf.jpl.nasa.gov/ or by email request to lawson@hucy.jpl.nasa.gov

  6. Atmospheric circulation in the early Holocene: Sensitivity of the North Atlantic winter climate to moderate changes in the ice-sheet configuration

    NASA Astrophysics Data System (ADS)

    Merz, N.; Raible, C. C.; Stocker, T. F.

    2012-04-01

    A prominent feature of interglacials, such as the Holocene, is the reduced size of the continental ice sheets. At present-day, only two ice-sheets (namely Greenland and Antarctica) exist which themselves are likely to retreat in the future due to global warming. Changes in the global ice-sheet distribution have distinct consequences for the surface climate and the atmospheric circulation since ice-masses shape the topography and define the local surface characteristics. Past interglacial periods offer the potential to study the climate dynamics and stability of warm periods, also concerning the impact of changes in the ice-sheet distribution. For this purpose, we use a comprehensive climate model to perform a set of time-slice simulations for the present, the early-Holocene and the Eemian warm period. In particular, we perform sensitivity experiments to assess the atmosphere's reaction to modest changes in the global ice-sheet distribution. In a first attempt, we focus on a set of four early-Holocene simulations which include the paleo-topographies from 9000BP, 8000BP, 7000BP and the present orography as lower boundary conditions, respectively. The early Holocene orography differs from the present-day state by the presence of remnants of the Laurentide ice-sheet and newly ice-free regions in Scandinavia and North America with a higher altitude due to the post-glacial rebound effect. For all simulations, the orbital forcing is set to the state of 8000BP, whereas the solar constant and greenhouse gas concentrations are fixed on pre-industrial levels. The Northern Hemisphere (NH) winter surface climate shows moderate and mostly non-significant changes due to the different lower boundaries. Significant differences in surface temperature are limited to areas which experience a local change in orography. However, there is a clear impact on the mid-level troposphere downstream of the Laurentide ice sheet remnants leading to a cooling over the North Atlantic and a warming over Southern Europe. These changes are likely associated with a change in the North Atlantic winter jet. The analysis shows that the sub-tropical branch of the jet is intensified whereas the eddy-driven jet is slightly weakened. Nevertheless, the induced changes in the jet do not lead to a change in the main NH modes of atmospheric variability (e.g., the North Atlantic Oscillation or the East Atlantic Pattern). This analysis illustrates that although the impact of the lower boundaries is significant, the magnitude is too small to lead to a significant reorganization of the mean atmospheric flow in the NH.

  7. Atmospheric Spread of Foot-and-mouth Disease During The Early Phase of The Uk Epidemic 2001

    NASA Astrophysics Data System (ADS)

    Sørensen, J. H.; Mikkelsen, T.; Astrup, P.; Alexandersen, S.; Donaldson, A. I.

    Foot-and-mouth disease (FMD) is a highly contagious viral disease in cloven-hoofed domesticated and wild animals. The highly contagious nature of FMD is a reflection of the wide range of species which are susceptible, the enormous quantities of virus liberated by infected animals, the range of excretions and secretions which can be infectious, the stability of the virus in the environment, the multiplicity of routes of infection and the very small doses of virus that can initiate infection in susceptible hosts. One of the routes for the spread of the disease is the atmospheric dispersion of virus exhaled by infected animals. Such spread can be rapid and extensive, and it is known in certain circumstances to have occurred over a distance of several hundred kilometres. For the FMD epidemic in UK in 2001, atmospheric dispersion models were applied in real time in order to describe the atmospheric dispersion of virus for the larger outbreaks of the disease. The operational value of such modelling is first of all to identify risk zones, which is helpful to the emergency management. The paper addresses the modelling techniques and presents results related with the epidemic in UK in 2001.

  8. Early Observations of the Upper Atmosphere and Ionosphere of Mars by MAVEN’s Neutral Gas and Ion Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Benna, Mehdi; Mahaffy, Paul R.; Elrod, Meredith

    2015-04-01

    The Neutral Gas and Ion Mass Spectrometer (NGIMS) of the Mars Atmosphere and Volatile Evolution (MAVEN) Mission is designed to characterize the source region of escaping atoms in the upper atmosphere and ionosphere of Mars. The NGIMS instrument is a quadrupole analyzer with a mass rang of 2-150 Da. It utilizes a dual ion source in order to measure both surface reactive neutrals (using the Open Source Neutral mode - OSN), inert neutrals (using the Closed Source Neutral mode – CSN), and thermal ions (using the Open Source Ion mode – OSI) at altitudes below 500 km.In the first few months of the MAVEN mission, NGIMS alternated on sequential orbits between measurement sequences that focus on fully characterizing neutral species (using the CSN/OSN modes) and ions (using the CSN/OSI modes). The collected data revealed the substantial structure present in both neutral and ion densities with spatial scales of hundreds of kilometers along the spacecraft track. The data also brought to light the sharp contrast between the day side and night side atmospheric profiles of neutrals and ions in both total density and relative abundance.

  9. Interaction of acid rain and global changes: Effects on terrestrial and aquatic ecosystems

    Microsoft Academic Search

    R. F. Wright; D. W. Schindler

    1995-01-01

    Both acid deposition and changes in the global atmosphere and climate affect terrestrial and aquatic ecosystems. In the atmosphere sulphate aerosols tend to increase haze, altering the global radiation balance. Increased nitrogen deposition to N-limited systems such as boreal forests results in increased growth and increased sequestration of atmospheric CO2, slowing the increase in CO2 levels in the atmosphere. Future

  10. Atmospheric aerosols as prebiotic chemical reactors.

    PubMed

    Dobson, C M; Ellison, G B; Tuck, A F; Vaida, V

    2000-10-24

    Aerosol particles in the atmosphere have recently been found to contain a large number of chemical elements and a high content of organic material. The latter property is explicable by an inverted micelle model. The aerosol sizes with significant atmospheric lifetimes are the same as those of single-celled organisms, and they are predicted by the interplay of aerodynamic drag, surface tension, and gravity. We propose that large populations of such aerosols could have afforded an environment, by means of their ability to concentrate molecules in a wide variety of physical conditions, for key chemical transformations in the prebiotic world. We also suggest that aerosols could have been precursors to life, since it is generally agreed that the common ancestor of terrestrial life was a single-celled organism. The early steps in some of these initial transformations should be accessible to experimental investigation. PMID:11035775

  11. Terrestrial teleconnections link global rivers

    NASA Astrophysics Data System (ADS)

    O'Loughlin, F.; Howden, N. J.; Woods, R. A.; Bates, P. D.

    2013-12-01

    We present analyses of river discharge data from across the world, which we used to identify links between annual river flow regimes across different continents. Our hypothesis was that, as atmospheric processes are subject to large-scale teleconnection patterns, and because these atmospheric processes are inherently linked to precipitation regimes across the world, there should be identifiable links between river flow regimes driven by these atmospheric processes. We used discharge data from the Global Runoff Data Centre (GRDC) to identify cross-correlations (and accounted for serial dependence) between 23 of the world's largest river basins where overlapping data were available over a period of 12 years or more: two in South America; five in Africa; one in Australasia; five in North America and ten in Eurasia. The selected river basins drain approximately a third of the Earth's landmass at their furthest downstream gauging station. Where significant cross-correlations were found, we compared these to known patterns associated with the ENSO and NAO teleconnections. In total, 85 of the 253 possible correlations were deemed significant at p<0.05, this reduced to 36 at p<0.01 and 21 at p<0.001. Of the significant correlations (p<0.05), 22 were classified as strong (r ?× 0.5), 45 as moderate (×0.5< r ?×0.25) and 18 as weak (×0.25< r >0). We compared these significant cross-correlations with known atmospheric teleconnection patterns, and while these were consistent for the majority of cases, we found a number of significant correlations that are inconsistent with the anticipated effects of known atmospheric teleconnections. Our results provide new insight into the inter-continental links between global river systems and the way in which these are controlled by large-scale atmospheric processes. We suggest this may be useful for global industries, such as insurers or aid agencies, who seek to understand correlations between the magnitudes of extreme events across different regions of the world. For the former, this may enable more efficient management of global liabilities, for the latter it may enable better logistical planning of disaster relief requirements. Aside from these practical applications, the results also suggest teleconnections exist between terrestrial, as well as ocean and atmospheric water systems.

  12. Extraterrestrial Life: Problem Set #1 Solutions 1) Explain briefly how the terrestrial planets (such as the Earth) differ from

    E-print Network

    Armitage, Phil

    Extraterrestrial Life: Problem Set #1 Solutions 1) Explain briefly how the terrestrial planets. The atmospheres of the terrestrial planets make up a very small fraction of the mass. The giant planets have planets all lie in the outer Solar System, exterior to the orbits of the terrestrial planets

  13. Dust direct radiative effects on the earth-atmosphere system over east Asia: Early spring cooling and late spring warming

    Microsoft Academic Search

    Hong Wang; TianLiang Zhao; XiaoYe Zhang; SunLing Gong

    2011-01-01

    Focusing on three dust storms occurring in spring 2001, we developed a detailed aerosol parameterization scheme and integrated\\u000a it in a radiative transfer model to characterize possible impacts of solar altitude angle on dust direct radiative effects\\u000a over China desert regions and the North Pacific, using actual daily solar altitude angles. Increasing solar altitude angle\\u000a from early spring (or winter)

  14. The effect of increased oxygen atmospheres on the early growth and development of chick embryos grown in plastic shells

    E-print Network

    Bryant, James Nathan

    1967-01-01

    that the plastic shell will provide an additional method to determine the causes of early embryonic mortality of the avian embryo. LITERATURE REVIEW Many attempts have been made to study the devel- oping embryo outside the normal shell; however, there have... days. Boone (1$6$) cultivated the chick embryo up to eight days using glass beakers. He suggested that one cause of death might be drying out of the embryo and the vitelline circulation resulting in increased fragility of the capillaries. Upon...

  15. Variability of terrestrial carbon cycle and its interaction with climate under global warming

    Microsoft Academic Search

    Haifeng Qian

    2008-01-01

    Land-atmosphere carbon exchange makes a significant contribution to the variability of atmospheric CO2 concentration on time scales of seasons to centuries. In this thesis, a terrestrial vegetation and carbon model, VEgetation-Global-Atmosphere-Soil (VEGAS), is used to study the interactions between the terrestrial carbon cycle and climate over a wide-range of temporal and spatial scales. The VEGAS model was first evaluated by

  16. Cometary origin of carbon and water on the terrestrial planets.

    PubMed

    Delsemme, A H

    1992-01-01

    An early high-temperature phase of the protosolar accretion disk is implied by at least three different telltales in chondrites and confirmed by peculiarities in the dust grains of comet Halley. The existence this high-temperature phase implies a large accretion rate hence a massive early disk. This clarifies the origin of the Kuiper Belt and of the Oort cloud, those two cometary populations of different symmetry that subsist today. Later, when the dust sedimented and was removed from the thermal equilibrium with the gas phase, a somewhat lower temperature of the disk explains the future planets' densities as well as the location beyond 2.6 AU of the carbonaceous chondrite chemistry. This lower temperature remains however large enough to require an exogenous origin for all carbon and all water now present in the Earth. The later orbital diffusion of planetesimals, which is required by protoplanelary growth, is needed to explain the origin of the terrestrial biosphere (atmosphere, oceans, carbonates and organic compounds) by a veneer mostly made of comets. PMID:11538154

  17. Abstracts for the International Workshop on Meteorite Impact on the Early Earth

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This volume contains abstracts that were accepted for presentation at the International Workshop on Meteorite Impact on the Early Earth, September 21-22, 1990, in Perth, Western Australia. The effects these impacts had on the young Earth are emphasized and a few of the topics covered are as follows: impact induced hot atmosphere, crater size and distribution, late heavy bombardment, terrestrial mantle and crust, impact damage, continental growth, volcanism, climate catastrophes, shocked quartz, and others.

  18. Terrestrial Planet Finder: science overview

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.; Beichman, C. A.

    2004-01-01

    The Terrestrial Planet Finder (TPF) seeks to revolutionize our understanding of humanity's place in the universe - by searching for Earth-like planets using reflected light, or thermal emission in the mid-infrared. Direct detection implies that TPF must separate planet light from glare of the nearby star, a technical challenge which has only in recent years been recognized as surmountable. TPF will obtain a low-resolution spectra of each planets it detects, providing some of its basic physical characteristics and its main atmospheric constituents, thereby allowing us to assess the likelihood that habitable conditions exist there. NASA has decided the scientific importance of this research is so high that TPF will be pursued as two complementary space observatories: a visible-light coronagraph and a mid-infrared formation flying interferometer. The combination of spectra from both wavebands is much more valuable than either taken separately, and it will allow a much fuller understanding of the wide diversity of planetary atmospheres that may be expected to exist. Measurements across a broad wavelength range will yield not only physical properties such as size and albedo, but will also serve as the foundations of a reliable and robust assessment of habitability and the presence of life.

  19. [Bites by terrestrial vertebrates].

    PubMed

    Henry, F; Martalo, O; Claessens, N; Piérard, G E

    2000-06-01

    Bites by terrestrial vertebrates, reptiles or mammals, represent a special risk in tropical regions. Envenomation is possible by a few lizards and many snakes. For mammals, tissular destructions due to the bite can be severe. Whatever is the offending animal, bites can further become infected by transmitted viruses or bacteria. PMID:10992781

  20. Terrestrials Dwarf Planets

    E-print Network

    Gaudi, B. Scott

    Terrestrials Gas Giants Ice Giants Dwarf Planets The Solar System #12;Neptune Uranus Saturn Jupiter Density: 3900 ­ 5500 kg m-3 #12;Jupiter 318 ME 5.2 AU Uranus 15 ME 19.6 AUSaturn 95 ME 9.5 AU Neptune 17 3.88 RE Uranus Neptune Uranus and Neptune are Ice Giants made mostly of ices with thin Hydrogen

  1. Terrestrial cosmic rays

    Microsoft Academic Search

    James F. Ziegler

    1996-01-01

    This paper reviews the basic physics of those cosmic rays which can affect terrestrial electronics. Cosmic rays at sea level consist mostly of neutrons, protons, pions, muons, electrons, and photons. The particles which cause significant soft fails in electronics are those particles with the strong interaction: neutrons, protons, and pions. At sea level, about 95% of these particles are neutrons.

  2. Terrestrial photovoltaic measurement procedures

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Procedures for obtaining cell and array current-voltage measurements both outdoors in natural sunlight and indoors in simulated sunlight are presented. A description of the necessary apparatus and equipment is given for the calibration and use of reference solar cells. Some comments relating to concentration cell measurements, and a revised terrestrial solar spectrum for use in theoretical calculations, are included.

  3. ExtraTerrestrial Intelligence

    E-print Network

    Walter, Frederick M.

    SETI Search for ExtraTerrestrial Intelligence I know perfectly well that at this moment the whole, The Madwoman of Chaillot #12;Options Passive SETI: Listen Active SETI: Transmit #12;Search Strategies Suppose you find a civilization. You want to communicate. How? #12;Search Strategies There are two issues: A

  4. A non-LTE study of silicon line formation in early-type main-sequence atmospheres.

    NASA Technical Reports Server (NTRS)

    Kamp, L. W.

    1973-01-01

    We have computed populations of 16 levels of Si III-V and radiation fields in all connecting transitions; in particular the first six Si III triplet levels, including the 4553 line, and the first six Si IV levels including 4089. The computations were done for four non-LTE H-He model atmospheres, provided by Auer and Mihalas. Estimates of corresponding MK types are B1.5 V, B0.5 V, O9 V, and O6. Solutions were obtained by iterating the linearized equations of radiative transfer and statistical equilibrium, except that for less important lines an approximate equivalent two-level atom treatment was used. Continuous opacities of C, N, O, and Ne were included. All abundances were solar values.

  5. Terrestrial water fluxes dominated by transpiration.

    PubMed

    Jasechko, Scott; Sharp, Zachary D; Gibson, John J; Birks, S Jean; Yi, Yi; Fawcett, Peter J

    2013-04-18

    Renewable fresh water over continents has input from precipitation and losses to the atmosphere through evaporation and transpiration. Global-scale estimates of transpiration from climate models are poorly constrained owing to large uncertainties in stomatal conductance and the lack of catchment-scale measurements required for model calibration, resulting in a range of predictions spanning 20 to 65 per cent of total terrestrial evapotranspiration (14,000 to 41,000 km(3) per year) (refs 1, 2, 3, 4, 5). Here we use the distinct isotope effects of transpiration and evaporation to show that transpiration is by far the largest water flux from Earth's continents, representing 80 to 90 per cent of terrestrial evapotranspiration. On the basis of our analysis of a global data set of large lakes and rivers, we conclude that transpiration recycles 62,000 ± 8,000 km(3) of water per year to the atmosphere, using half of all solar energy absorbed by land surfaces in the process. We also calculate CO2 uptake by terrestrial vegetation by connecting transpiration losses to carbon assimilation using water-use efficiency ratios of plants, and show the global gross primary productivity to be 129 ± 32 gigatonnes of carbon per year, which agrees, within the uncertainty, with previous estimates. The dominance of transpiration water fluxes in continental evapotranspiration suggests that, from the point of view of water resource forecasting, climate model development should prioritize improvements in simulations of biological fluxes rather than physical (evaporation) fluxes. PMID:23552893

  6. Volcanic ash - Terrestrial versus extraterrestrial

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.

    1976-01-01

    A principal difference between terrestrial and extraterrestrial lavas may consist in the greater ability of terrestrial lavas to form thin films (like those of soap bubbles) and hence foams. It would follow that, in place of the pumice and spiny shards found in terrestrial volcanic ash, an extraterrestrial ash should contain minute spherules. This hypothesis may help to explain lunar microspherules.

  7. Arsenic Speciation of Terrestrial Invertebrates

    Microsoft Academic Search

    Maeve M. Moriarty; Iris Koch; Robert A. Gordon; Kenneth J. Reimer

    2009-01-01

    The distribution and chemical form (speciation) of arsenic in terrestrial food chains determines both the amount of arsenic available to higher organisms, and the toxicity of this metalloid in affected ecosystems. Invertebrates are part of complex terrestrial food webs. This paper provides arsenic concentrations and arsenic speciation profiles for eight orders of terrestrial invertebrates collected at three historical gold mine

  8. Origin and evolution of the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Pollack, J. B.

    1983-01-01

    Implications for the origin and evolution of the terrestrial planets are drawn from a comparison of the Venus, earth and Mars atmosphere volatile inventories. Attention is given to the possible loss of an appreciable amount of water from Venus, in light of recent evidence for a 100-fold deuterium enrichment. Ar-40 and He-4 abundances suggest that outgassing has been inefficient for much of Venus's lifetime, in keeping with evidence for a lower level of tectonic activity on Venus than on the earth. Attention is also given to Venus's CO2 geochemistry. The picture now emerging is that of a Venus that began to evolve along a path similar to that of the earth, but suffered a catastrophic, runaway greenhouse effect early in its lifetime. How early the castastrophe occurred may be suggested by the presently low inventories of radiogenic argon and helium in its atmosphere.

  9. Early plume and shock wave dynamics in atmospheric-pressure ultraviolet-laser ablation of different matrix-assisted laser ablation matrices

    SciTech Connect

    Schmitz, Thomas A.; Koch, Joachim; Guenther, Detlef; Zenobi, Renato [Department of Chemistry and Applied Biosciences, ETH Zuerich, 8093 Zuerich (Switzerland)

    2011-06-15

    Pulsed laser ablation of molecular solids is important for identification and quantification in (bio-)organic mass spectrometry, for example using matrix-assisted laser desorption/ionization (MALDI). Recently, there has been a major shift to using MALDI and related laser ablation/post-ionization methods at atmospheric pressure. However, the underlying laser ablation processes, in particular early plume formation and expansion, are still poorly understood. Here, we present a study of the early ablation processes on the ns-time scale in atmospheric pressure UV-laser ablation of anthracene as well as of different common MALDI matrices such as 2,5-dihydroxybenzoic acid (2,5-DHB), {alpha}-cyano-4-hydroxycinnamic acid and sinapinic acid. Material release as well as the formation and expansion of hemi-spherical shock waves were studied by shadowgraphy with high temporal resolution ({approx}5 ns). The applicability of the classical Taylor-Sedov model for expansion of strong shock waves ('point-blast model'), as well as the drag force model, were evaluated to mathematically describe the observed shock wave propagation. The time- and energy-dependent expansion of the shock waves could be described using a Taylor-Sedov scaling law of the form R {proportional_to} t{sup q}, when a q-exponent of {approx}0.5 instead of the theoretical value of q 0.4 was found, indicating a faster expansion than expected. The deviations from the ideal value of q were attributed to the non-negligible influence of ambient pressure, a weak versus strong shock regime, and additional acceleration processes present in laser ablation that surpass the limit of the point-blast model. The onset of shock wave formation at a fluence of {approx}15-30 mJ/cm{sup 2} for the compounds investigated coincides with the onset of bulk material release, whereas, pure desorption below this fluence threshold did not lead to features visible in shadowgraphy.

  10. Early plume and shock wave dynamics in atmospheric-pressure ultraviolet-laser ablation of different matrix-assisted laser ablation matrices

    NASA Astrophysics Data System (ADS)

    Schmitz, Thomas A.; Koch, Joachim; Günther, Detlef; Zenobi, Renato

    2011-06-01

    Pulsed laser ablation of molecular solids is important for identification and quantification in (bio-)organic mass spectrometry, for example using matrix-assisted laser desorption/ionization (MALDI). Recently, there has been a major shift to using MALDI and related laser ablation/post-ionization methods at atmospheric pressure. However, the underlying laser ablation processes, in particular early plume formation and expansion, are still poorly understood. Here, we present a study of the early ablation processes on the ns-time scale in atmospheric pressure UV-laser ablation of anthracene as well as of different common MALDI matrices such as 2,5-dihydroxybenzoic acid (2,5-DHB), ?-cyano-4-hydroxycinnamic acid and sinapinic acid. Material release as well as the formation and expansion of hemi-spherical shock waves were studied by shadowgraphy with high temporal resolution (˜5 ns). The applicability of the classical Taylor-Sedov model for expansion of strong shock waves ("point-blast model"), as well as the drag force model, were evaluated to mathematically describe the observed shock wave propagation. The time- and energy-dependent expansion of the shock waves could be described using a Taylor-Sedov scaling law of the form R ? tq, when a q-exponent of ˜0.5 instead of the theoretical value of q = 0.4 was found, indicating a faster expansion than expected. The deviations from the ideal value of q were attributed to the non-negligible influence of ambient pressure, a weak versus strong shock regime, and additional acceleration processes present in laser ablation that surpass the limit of the point-blast model. The onset of shock wave formation at a fluence of ˜15-30 mJ/cm2 for the compounds investigated coincides with the onset of bulk material release, whereas, pure desorption below this fluence threshold did not lead to features visible in shadowgraphy.

  11. Terrestrial cooling in Northern Europe during the eocene-oligocene transition.

    PubMed

    Hren, Michael T; Sheldon, Nathan D; Grimes, Stephen T; Collinson, Margaret E; Hooker, Jerry J; Bugler, Melanie; Lohmann, Kyger C

    2013-05-01

    Geochemical and modeling studies suggest that the transition from the "greenhouse" state of the Late Eocene to the "icehouse" conditions of the Oligocene 34-33.5 Ma was triggered by a reduction of atmospheric pCO2 that enabled the rapid buildup of a permanent ice sheet on the Antarctic continent. Marine records show that the drop in pCO2 during this interval was accompanied by a significant decline in high-latitude sea surface and deep ocean temperature and enhanced seasonality in middle and high latitudes. However, terrestrial records of this climate transition show heterogeneous responses to changing pCO2 and ocean temperatures, with some records showing a significant time lag in the temperature response to declining pCO2. We measured the ?47 of aragonite shells of the freshwater gastropod Viviparus lentus from the Solent Group, Hampshire Basin, United Kingdom, to reconstruct terrestrial temperature and hydrologic change in the North Atlantic region during the Eocene-Oligocene transition. Our data show a decrease in growing-season surface water temperatures (~10 °C) during the Eocene-Oligocene transition, corresponding to an average decrease in mean annual air temperature of ~4-6 °C from the Late Eocene to Early Oligocene. The magnitude of cooling is similar to observed decreases in North Atlantic sea surface temperature over this interval and occurs during major glacial expansion. This suggests a close linkage between atmospheric carbon dioxide concentrations, Northern Hemisphere temperature, and expansion of the Antarctic ice sheets. PMID:23610424

  12. Abiotic nitrogen fixation on terrestrial planets: reduction of NO to ammonia by FeS.

    PubMed

    Summers, David P; Basa, Ranor C B; Khare, Bishun; Rodoni, David

    2012-02-01

    Understanding the abiotic fixation of nitrogen and how such fixation can be a supply of prebiotic nitrogen is critical for understanding both the planetary evolution of, and the potential origin of life on, terrestrial planets. As nitrogen is a biochemically essential element, sources of biochemically accessible nitrogen, especially reduced nitrogen, are critical to prebiotic chemistry and the origin of life. Loss of atmospheric nitrogen can result in loss of the ability to sustain liquid water on a planetary surface, which would impact planetary habitability and hydrological processes that shape the surface. It is known that NO can be photochemically converted through a chain of reactions to form nitrate and nitrite, which can be subsequently reduced to ammonia. Here, we show that NO can also be directly reduced, by FeS, to ammonia. In addition to removing nitrogen from the atmosphere, this reaction is particularly important as a source of reduced nitrogen on an early terrestrial planet. By converting NO directly to ammonia in a single step, ammonia is formed with a higher product yield (~50%) than would be possible through the formation of nitrate/nitrite and subsequent conversion to ammonia. In conjunction with the reduction of NO, there is also a catalytic disproportionation at the mineral surface that converts NO to NO? and N?O. The NO? is then converted to ammonia, while the N?O is released back in the gas phase, which provides an abiotic source of nitrous oxide. PMID:22283408

  13. Terrestrial cooling in Northern Europe during the Eocene–Oligocene transition

    PubMed Central

    Hren, Michael T.; Sheldon, Nathan D.; Grimes, Stephen T.; Collinson, Margaret E.; Hooker, Jerry J.; Bugler, Melanie; Lohmann, Kyger C.

    2013-01-01

    Geochemical and modeling studies suggest that the transition from the “greenhouse” state of the Late Eocene to the “icehouse” conditions of the Oligocene 34–33.5 Ma was triggered by a reduction of atmospheric pCO2 that enabled the rapid buildup of a permanent ice sheet on the Antarctic continent. Marine records show that the drop in pCO2 during this interval was accompanied by a significant decline in high-latitude sea surface and deep ocean temperature and enhanced seasonality in middle and high latitudes. However, terrestrial records of this climate transition show heterogeneous responses to changing pCO2 and ocean temperatures, with some records showing a significant time lag in the temperature response to declining pCO2. We measured the ?47 of aragonite shells of the freshwater gastropod Viviparus lentus from the Solent Group, Hampshire Basin, United Kingdom, to reconstruct terrestrial temperature and hydrologic change in the North Atlantic region during the Eocene–Oligocene transition. Our data show a decrease in growing-season surface water temperatures (?10 °C) during the Eocene–Oligocene transition, corresponding to an average decrease in mean annual air temperature of ?4–6 °C from the Late Eocene to Early Oligocene. The magnitude of cooling is similar to observed decreases in North Atlantic sea surface temperature over this interval and occurs during major glacial expansion. This suggests a close linkage between atmospheric carbon dioxide concentrations, Northern Hemisphere temperature, and expansion of the Antarctic ice sheets. PMID:23610424

  14. Non-LTE, line-blanketed model atmospheres for late O- and early B-type stars

    NASA Technical Reports Server (NTRS)

    Grigsby, James A.; Morrison, Nancy D.; Anderson, Lawrence S.

    1992-01-01

    The use of non-LTE line-blanketed model atmospheres to analyze the spectra of hot stars is reported. The stars analyzed are members of clusters and associations, have spectral types in the range O9-B2 and luminosity classes in the range III-IV, have slow to moderate rotation, and are photometrically constant. Sampled line opacities of iron-group elements were incorporated in the radiative transfer solution; solar abundances were assumed. Good to excellent agreement is obtained between the computed profiles and essentially all the line profiles used to fix the model, and reliable stellar parameters are derived. The synthetic M II 5581 equivalent widths agree well with the observed ones at the low end of the temperature range studied, but, above 25,000 K, the synthetic line is generally stronger than the observed line. The behavior of the observed equivalent widths of N II, N III, C II and C III lines as a function of Teff is studied. Most of the lines show much scatter, with no consistent trend that could indicate abundance differences from star to star.

  15. Deciphering Thermal Phase Curves of Dry, Tidally Locked Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Koll, Daniel D. B.; Abbot, Dorian S.

    2015-03-01

    Next-generation space telescopes will allow us to characterize terrestrial exoplanets. To do so effectively it will be crucial to make use of all available data. We investigate which atmospheric properties can, and cannot, be inferred from the broadband thermal phase curve of a dry and tidally locked terrestrial planet. First, we use dimensional analysis to show that phase curves are controlled by six nondimensional parameters. Second, we use an idealized general circulation model to explore the relative sensitivity of phase curves to these parameters. We find that the feature of phase curves most sensitive to atmospheric parameters is the peak-to-trough amplitude. Moreover, except for hot and rapidly rotating planets, the phase amplitude is primarily sensitive to only two nondimensional parameters: (1) the ratio of dynamical to radiative timescales and (2) the longwave optical depth at the surface. As an application of this technique, we show how phase curve measurements can be combined with transit or emission spectroscopy to yield a new constraint for the surface pressure and atmospheric mass of terrestrial planets. We estimate that a single broadband phase curve, measured over half an orbit with the James Webb Space Telescope, could meaningfully constrain the atmospheric mass of a nearby super-Earth. Such constraints will be important for studying the atmospheric evolution of terrestrial exoplanets as well as characterizing the surface conditions on potentially habitable planets.

  16. Assessment of Present-Day vs. Lateglacial/Early Holocene climate variability and atmospheric CO2 changes from tree-ring stable isotope time series

    NASA Astrophysics Data System (ADS)

    Pieper, H.; Helle, G.; Brauer, A.; Kaiser, K. F.; Miramont, C.

    2012-12-01

    The Younger Dryas interval during the Last Glacial Termination was an abrupt return to glacial-like conditions punctuating the transition to a warmer, interglacial climate. Despite recent advances in the layer counting of ice-core records of the termination, the timing and length of the Younger Dryas remain controversial. Late Glacial and early Holocene tree-ring chronologies are rare, however, they contain valuable information about past environmental conditions at annual time resolution. Changes in tree-ring growth rates can be related to past climate anomalies and changes in the carbon and oxygen isotope composition of tree-ring cellulose reflect atmospheric and hydrospheric changes. We are investigating a 600-year (13100 - 12500 cal BP) absolutely dated dendrochronological record of Late Glacial and Early Holocene chronologies of scots pine (Pinus sylvestris L.) from subfossil tree remnants from Barbiers River (Moyenne Durance, Southern French Alps), as well as from Swiss (Dättnau, Landikon and Gänziloh) and German (Cottbus) sites. Dendro-ecological parameters, such as ring width and stable isotope variations (? 13C und ? 18O) are used to infer past environmental conditions. We will present our first oxygen isotope records from tree rings reflecting the environmental changes of a ca. 300 year period between 12790 - 12478 cal BP.

  17. Polar terrestrial ecosystems, permafrost, and extreme warm paleoclimate dynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Deconto, R.; Pagani, M.; Pollard, D.; Beerling, D. J.

    2009-12-01

    Coupled Global Climate Model (GCM)-vegetation simulations of Mesozoic and early Cenozoic “greenhouse” paleoclimates show the importance of terrestrial ecosystems in maintaining warm continental interiors and ice-free polar land areas. Such simulations also offer excellent potential for model-data comparison, because simulated distributions of vegetation reflect a more complete seasonal picture of regional climates than the mean annual conditions reflected in most geochemical proxies. Terrestrial ecosystems may have also played a critical role in extreme climate events, such as the Palaeocene-Eocene Thermal Maximum (PETM) hyperthermal event (~55 Ma). Hitherto, most explanations of this event point to a release of isotopically light (-60 ‰) marine gas hydrate (methane) as the most likely cause of the ~3 ‰ carbon isotope shift and sudden 5-9 deg C global warming that characterize the event. However, mass balance arguments suggest the mass of carbon from this reservoir is insufficient to cause the presumed warming, leaving the source of the carbon and/or the strength of amplifying warming feedbacks an open question. Here we use results from a GCM to show that Antarctica was a suitable location for massive carbon sequestration in peat and permafrost-dominated environments during the Palaeocene leading up the PETM event. Levels of assumed atmospheric CO2 and CH4 concentrations around the time of the event are shown to cross the threshold for melting vast areas of frozen soil on an unglaciated Antarctic continent, which had a subaerial surface area ~25% larger than today. This previously underappreciated potential source of carbon would have been large enough to account for a significant fraction of the total warming at the PETM once a warming threshold was reached, whereby permafrost began to melt and methane and relict soil carbon were suddenly released. If this mechanism did play a role in abrupt and extreme global warming events such as the PETM, it implies serious consequences for the thawing of similar environments in the modern boreal high latitudes.

  18. Biological fixation of atmospheric nitrogen in the Mediterranean Sea

    Microsoft Academic Search

    J. PIERRE BÉTHOUX; G. Copin-Montegut

    1986-01-01

    Nutrient concentration in the Mediterranean Sea is controlled by water exchanges through the Strait of Gibraltar and by atmospheric and terrestrial inputs. Various peculiarities in the nitrogen and phosphorus geochemical cycles are pointed out, namely a low N:P atomic ratio (6.4) in terrestrial discharges, and a budget well balanced for phosphorus (where terrestrial discharges amount to about 80% of the

  19. Making More Terrestrial Planets

    Microsoft Academic Search

    J. E. Chambers

    2001-01-01

    The results of 16 new 3D N-body simulations of the final stage of the formation of the terrestrial planets are presented. These N-body integrations begin with 150–160 lunar-to-Mars size planetary embryos, with semi-major axes 0.3

  20. A catalog of atmospheric densities from the drag on five balloon satellites

    NASA Technical Reports Server (NTRS)

    Jacchia, L. G.; Slowey, J. W.

    1975-01-01

    A catalog of atmospheric densities derived for the drag on five balloon satellites is presented. Much of the catalog was based on precisely reduced Baker-Nunn observations and, for that reason, provides much improved time resolution. The effect of direct solar radiation pressure was precisely evaluated, and that of terrestrial radiation pressure was included in every case. The interval covered for each satellite varies between 3.1 and 7.6 years, with the data extending from early 1961 to early 1973.

  1. Recent climate-induced variations in terrestrial carbon cycle over tropics: A model simulation

    Microsoft Academic Search

    K. Ichii; R. R. Nemani; H. Hashimoto

    2003-01-01

    Tropical forests accounts for about 20 percent of the world terrestrial carbon and one-third of global terrestrial NPP. Atmospheric inversion studies show that additional factors such as CO2 fertilization and climate changes, should work as a carbon sink despite of CO2 emission due to deforestation in tropical regions. However, responses of tropical ecosystems to environmental changes and current carbon sink

  2. Classification and generation of terrestrial rare gases

    NASA Technical Reports Server (NTRS)

    Saito, K.

    1978-01-01

    A Kr-84/Xe-130 versus Ne-20/Ar-36 diagram is a very useful format with which to study the elemental ratios of rare gases from terrestrial materials. It can separate not only the three types of rare gases which Ozima and Alexander (1976) classified but also the 'planetary' type rare gases from the other three types of rare gases. When all the available terrestrial rare gas data are plotted in a Kr-84/Xe-130 versus Ne-20/Ar-36 diagram, several observations can be made. First, most of the analyses of rare gases from shales yield Kr-84/Xe-130 ratios between the 'planetary' and atmospheric values. If, however, the atmosphere's high Kr-84/Xe-130 ratio was produced by the selective adsorption of xenon onto shales from an initially 'planetary' atmosphere, as is widely accepted, then the Kr-84/Xe-130 ratio in shales should be even lower than the 'planetary' value. Second, the rare gas pattern in the quenched rims of submarine basalts may be explained as fractionated samples of the rare gases in sea water.

  3. Space and Terrestrial Photovoltaics: Synergy and Diversity

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila; Raffaelle, Ryne; Emery, Keith

    2002-01-01

    A historical view of the research and development in photovoltaics from the perspective of both the terrestrial and the space communities is presented from the early days through the '70s and '80s and the '90s and beyond. The synergy of both communities in the beginning and once again in the present and hopefully future are highlighted, with examples of the important features in each program. The space community which was impressed by the light-weight and reliability of photovoltaics drove much of the early development. Even up to today, nearly every satellites and other scientific space probe that has been launched has included some solar power. However, since the cost of these power systems were only a small fraction of the satellite and launch cost, the use of much of this technology for the terrestrial marketplace was not feasible. It was clear that the focus of the terrestrial community would be best served by reducing costs. This would include addressing a variety of manufacturing issues and raising the rate of production. Success in these programs and a resulting globalization of effort resulted in major strides in the reduction of PV module costs and increased production. Although, the space community derived benefit from some of these advancements, its focus was on pushing the envelope with regard to cell efficiency. The gap between theoretical efficiencies and experimental efficiencies for silicon, gallium arsenide and indium phosphide became almost non-existent. Recent work by both communities have focused on the development thin film cells of amorphous silicon, CuInSe2 and CdTe. These cells hold the promise of lower costs for the terrestrial community as well as possible flexible substrates, better radiation resistance, and higher specific power for the space community. It is predicted that future trends in both communities will be directed toward advances through the application of nanotechnology. A picture is emerging in which the space and terrestrial solar cell communities shall once again share many common goals and, in fact, companies may manufacture both space and terrestrial solar cells in III-V materials and thin film materials. Basic photovoltaics research including these current trends in nanotechnology provides a valuable service for both worlds in that fundamental understanding of cell processes is still vitally important, particularly with new materials or new cell structures. It is entirely possible that one day we might have one solar array design that will meet the criteria for success in both space and on the Earth or perhaps the Moon or Mars.

  4. Space and Terrestrial Photovoltaics: Synergy and Diversity

    NASA Astrophysics Data System (ADS)

    Bailey, Sheila; Raffaelle, Ryne; Emery, Keith

    2002-10-01

    A historical view of the research and development in photovoltaics from the perspective of both the terrestrial and the space communities is presented from the early days through the '70s and '80s and the '90s and beyond. The synergy of both communities in the beginning and once again in the present and hopefully future are highlighted, with examples of the important features in each program. The space community which was impressed by the light-weight and reliability of photovoltaics drove much of the early development. Even up to today, nearly every satellites and other scientific space probe that has been launched has included some solar power. However, since the cost of these power systems were only a small fraction of the satellite and launch cost, the use of much of this technology for the terrestrial marketplace was not feasible. It was clear that the focus of the terrestrial community would be best served by reducing costs. This would include addressing a variety of manufacturing issues and raising the rate of production. Success in these programs and a resulting globalization of effort resulted in major strides in the reduction of PV module costs and increased production. Although, the space community derived benefit from some of these advancements, its focus was on pushing the envelope with regard to cell efficiency. The gap between theoretical efficiencies and experimental efficiencies for silicon, gallium arsenide and indium phosphide became almost non-existent. Recent work by both communities have focused on the development thin film cells of amorphous silicon, CuInSe2 and CdTe. These cells hold the promise of lower costs for the terrestrial community as well as possible flexible substrates, better radiation resistance, and higher specific power for the space community. It is predicted that future trends in both communities will be directed toward advances through the application of nanotechnology. A picture is emerging in which the space and terrestrial solar cell communities shall once again share many common goals and, in fact, companies may manufacture both space and terrestrial solar cells in III-V materials and thin film materials. Basic photovoltaics research including these current trends in nanotechnology provides a valuable service for both worlds in that fundamental understanding of cell processes is still vitally important, particularly with new materials or new cell structures. It is entirely possible that one day we might have one solar array design that will meet the criteria for success in both space and on the Earth or perhaps the Moon or Mars.

  5. Terrestrial Effects of High Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Atri, Dimitra

    2011-01-01

    On geological timescales, the Earth is likely to be exposed to an increased flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles. Increased ionization could lead to changes in atmospheric chemistry, resulting in ozone depletion. This could increase the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit can could possibly enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of nuclear interactions are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates radiation dose from cosmic rays causing DNA damage and increase in the mutation rates, which can have serious biological implications for terrestrial and sub-terrestrial life. This radiation dose is an important constraint on the habitability of a planet. Using CORSIKA, we perform massive computer simulations and construct lookup tables from 10 GeV - 1 PeV primaries (1 PeV - 0.1 ZeV in progress), which can be used to quantify these effects. These tables are freely available to the community and can be used for other studies, not necessarily relevant to Astrobiology. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. This could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

  6. Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

    PubMed Central

    Algeo, T. J.

    1998-01-01

    The Devonian Period was characterized by major changes in both the terrestrial biosphere, e.g. the evolution of trees and seed plants and the appearance of multi-storied forests, and in the marine biosphere, e.g. an extended biotic crisis that decimated tropical marine benthos, especially the stromatoporoid-tabulate coral reef community. Teleconnections between these terrestrial and marine events are poorly understood, but a key may lie in the role of soils as a geochemical interface between the lithosphere and atmosphere/hydrosphere, and the role of land plants in mediating weathering processes at this interface. The effectiveness of terrestrial floras in weathering was significantly enhanced as a consequence of increases in the size and geographic extent of vascular land plants during the Devonian. In this regard, the most important palaeobotanical innovations were (1) arborescence (tree stature), which increased maximum depths of root penetration and rhizoturbation, and (2) the seed habit, which freed land plants from reproductive dependence on moist lowland habitats and allowed colonization of drier upland and primary successional areas. These developments resulted in a transient intensification of pedogenesis (soil formation) and to large increases in the thickness and areal extent of soils. Enhanced chemical weathering may have led to increased riverine nutrient fluxes that promoted development of eutrophic conditions in epicontinental seaways, resulting in algal blooms, widespread bottomwater anoxia, and high sedimentary organic carbon fluxes. Long-term effects included drawdown of atmospheric pCO2 and global cooling, leading to a brief Late Devonian glaciation, which set the stage for icehouse conditions during the Permo-Carboniferous. This model provides a framework for understanding links between early land plant evolution and coeval marine anoxic and biotic events, but further testing of Devonian terrestrial-marine teleconnections is needed.

  7. Atmospheric Radiative Transfer

    Microsoft Academic Search

    Bruno Sportisse

    The interaction between atmospheric matter and solar and terrestrial radiation plays a leading role for life conditions at\\u000a the Earth’s surface: \\u000a \\u000a \\u000a \\u000a • \\u000a \\u000a stratospheric ozone filters the solar ultraviolet radiation;\\u000a \\u000a \\u000a • \\u000a \\u000a the absorption by a few gas-phase species (e.g. water, methane or carbon dioxide) of the terrestrial radiation defines the\\u000a so-called greenhouse effect, which results in a surface temperature greater than

  8. Terrestrial nitrogen–carbon cycle interactions at the global scale

    PubMed Central

    Zaehle, S.

    2013-01-01

    Interactions between the terrestrial nitrogen (N) and carbon (C) cycles shape the response of ecosystems to global change. However, the global distribution of nitrogen availability and its importance in global biogeochemistry and biogeochemical interactions with the climate system remain uncertain. Based on projections of a terrestrial biosphere model scaling ecological understanding of nitrogen–carbon cycle interactions to global scales, anthropogenic nitrogen additions since 1860 are estimated to have enriched the terrestrial biosphere by 1.3 Pg N, supporting the sequestration of 11.2 Pg C. Over the same time period, CO2 fertilization has increased terrestrial carbon storage by 134.0 Pg C, increasing the terrestrial nitrogen stock by 1.2 Pg N. In 2001–2010, terrestrial ecosystems sequestered an estimated total of 27 Tg N yr?1 (1.9 Pg C yr?1), of which 10 Tg N yr?1 (0.2 Pg C yr?1) are due to anthropogenic nitrogen deposition. Nitrogen availability already limits terrestrial carbon sequestration in the boreal and temperate zone, and will constrain future carbon sequestration in response to CO2 fertilization (regionally by up to 70% compared with an estimate without considering nitrogen–carbon interactions). This reduced terrestrial carbon uptake will probably dominate the role of the terrestrial nitrogen cycle in the climate system, as it accelerates the accumulation of anthropogenic CO2 in the atmosphere. However, increases of N2O emissions owing to anthropogenic nitrogen and climate change (at a rate of approx. 0.5 Tg N yr?1 per 1°C degree climate warming) will add an important long-term climate forcing. PMID:23713123

  9. Influence of Geoengineered Climate on the Terrestrial Biosphere

    Microsoft Academic Search

    Vaishali Naik; Donald J. Wuebbles; Evan H. DeLucia; Jonathan A. Foley

    2003-01-01

    Various geoengineering schemes have been proposed to counteract anthropogenically induced climate change. In a previous study, it was suggested that a 1.8% reduction in solar radiation incident on the Earth’s surface could noticeably reduce regional and seasonal climate change from increased atmospheric carbon dioxide (CO 2). However, the response of the terrestrial biosphere to reduced solar radiation in a CO

  10. Terrestrial Planet Finder Coronagraph overview of technology development & system design

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjuthapatham; Ford, Virginia; Mouroulis, Pantazis; Hoppe, Daniel; Shaklan, Stuart

    2004-01-01

    Astronomers have discovered over 150 planets orbiting other stars. NASA mission; Find and characterize terrestrial (or rocky) exo-planets that might harbor life (like Earth)liquid water on the planet (habitable zone). An atmosphere that indicates the presence of life water, oxygen, ozone, carbon dioxide, chlorophyll, and methane. Two missions under development: A coronagraph and an interferometer.

  11. THE DEFINITION AND INTERPRETATION OF TERRESTRIAL ENVIRONMENT DESIGN INPUTS FOR VEHICLE DESIGN CONSIDERATIONS

    NASA Technical Reports Server (NTRS)

    Johnson, Dale L.; Keller, Vernon W.; Vaughan, William W.

    2005-01-01

    The description and interpretation of the terrestrial environment (0-90 km altitude) is an important driver of aerospace vehicle structural, control, and thermal system design. NASA is currently in the process of reviewing the meteorological information acquired over the past decade and producing an update to the 1993 Terrestrial Environment Guidelines for Aerospace Vehicle Design and Development handbook. This paper addresses the contents of this updated handbook, with special emphasis on new material being included in the areas of atmospheric thermodynamic models, wind dynamics, atmospheric composition, atmospheric electricity, cloud phenomena, atmospheric extremes, sea state, etc. In addition, the respective engineering design elements will be discussed relative to the importance and influence of terrestrial environment inputs that require consideration and interpretation for design applications. Specific lessons learned that have contributed to the advancements made in the acquisition, interpretation, application and awareness of terrestrial environment inputs for aerospace engineering applications are discussed.

  12. Strong carbon release from the deep ocean induced a major atmospheric 14C drop over Heinrich Stadial 1

    NASA Astrophysics Data System (ADS)

    Sarnthein, M.; Grootes, P. M.; Schneider, B.

    2012-12-01

    Using the modern global distributions of apparent 14C ventilation ages and DIC we established a transfer function to trace past changes in the carbon storage of ocean waters >2000 m water depth. On this basis we concluded that the LGM carbon inventory was approximately 730-980 Gt larger than during pre-industrial times. This amount compares well with an estimated glacial transfer of 530-700 Gt from both the atmosphere and terrestrial biosphere in addition to a major DIC relocation from ocean intermediate waters. We consider that the LGM atmosphere contained 190 ppm CO2 (~375 Gt C) with a 14C concentration 1.4 times higher than that of the standard modern atmosphere (fMC) (Reimer et al. 2009). The LGM deep ocean had an average reservoir age of 2100 yr, which means that its 14C concentration was 0.77 times that of the LGM atmosphere, 1.08 times that of the modern atmosphere (fMC). During the subsequent early deglac¬ial Heinrich Stadial 1, a large portion of this 14C depleted carbon was released to the atmosphere and terrestrial biosphere (Monnin et al. 2001; Ciais et al. 2012). Our estimates suggest that the ocean-atmosphere exchange, producing this deglacial transfer of deep-ocean carbon, was sufficient to account for a 190-permil drop in atmospheric 14C. Thus an alleged major 'mystery' of last deglacial times, the source of 14C-depleted additional atmospheric carbon, appears solved. -- Ciais, P., Tagliabue, A., Cuntz, M., Bopp, L., et al. (2012), Large inert carbon pool in the terrestrial biosphere during the Last Glacial Maximum. Nature Geoscience 5, 74-79. Monnin, E., et al. (2001), Atmospheric CO2 concentrations over the last glacial termination. Science 291, 112-114. Reimer, P., et al. (2009), INTCAL09 and MARINE09 radiocarbon age calibration curves, 0-50,000 years cal. BP. Radiocarbon 51, 1111-1150.

  13. Microbial life in terrestrial permafrost: methanogenesis and nitrification in Gelisols as potentials for exobiological processes

    NASA Astrophysics Data System (ADS)

    Wagner, Dirk; Spieck, Eva; Bock, Eberhard; Pfeiffer, Eva-Maria

    The comparability of environmental and climatic conditions of the early Mars and Earth is of special interest for the actual research in astrobiology. Martian surface and terrestrial permafrost areas show similar morphological structures, which suggests that their development is based on comparable processes. Soil microbial investigations of adaptation strategies of microorganisms from terrestrial permafrost in combination with environmental, geochemical and physical analyses give insights into early stages of life on Earth. The extreme conditions in terrestrial permafrost soils can help to understand the evolution of life on early Mars and help searching for possible niches of life on present Mars or in other extraterrestrial permafrost habitats.

  14. LIFETIME OF EXCESS ATMOSPHERIC CARBON DIOXIDE

    EPA Science Inventory

    We explore the effects of a changing terrestrial biosphere on the atmospheric residende time of carbon dioxide using three simple ocean carbon cycling models and a model of global terrestrial carbon cycling. e find differences in model behavior associated with the assumption of a...

  15. Antarctic terrestrial ecosystems

    SciTech Connect

    Walton, D.W.H.

    1987-01-01

    The Maritime and Continental Antarctic terrestrial ecosystems are considered in the context of environmental impacts - habitat destruction, alien introductions, and pollution. Four types of pollution are considered: nutrients, radionuclides, inert materials, and noxious chemicals. Their ability to recover from perturbation is discussed in the light of present scientific knowledge, and the methods used to control impacts are reviewed. It is concluded that techniques of waste disposal are still inadequate, adequate training in environmental and conservation principles for Antarctic personnel in many countries is lacking, and scientific investigations may be a much more serious threat than tourism to the integrity of these ecosystems. Some priorities crucial to future management are suggested.

  16. Transient climate change and net ecosystem production of the terrestrial biosphere

    Microsoft Academic Search

    Xiangming Xiao; J. M. Melillo; D. W. Kicklighter; A. D. McGuire; R. G. Prinn; Chien Wang; P. H. Stone; Andrei P. Sokolov

    1998-01-01

    In this sensitivity study, we have applied the Terrestrial Ecosystem Model ((TEM) version 4.1) to examine the responses of terrestrial ecosystems to transient changes in atmospheric CO2 concentration and climate in the 21st century at the scales of the globe, biomes, latitudinal gradient, and economic regions. Three predictions of transient change in climate and atmospheric CO2 concentration in the 21st

  17. Sensitivity of the terrestrial planet finder

    NASA Technical Reports Server (NTRS)

    Beichman, Charles

    1998-01-01

    A key long-term goal of NASA's Origins program is the detection and characterization of habitable planets orbiting stars within the solar neighborhood. A cold, space-borne interferometer operating in the mid-infrared with a approx. 75 m baseline can null the light of a parent star and detect the million-times fainter radiation from an Earth-like planet located in the "habitable zone" around stars as far as 15 pc away. Such an interferometer, designated the Terrestrial Planet Finder (TPF) by NASA, could even detect atmospheric signatures of species such as CO2, O3, and H2O indicative of either the possibility or presence of primitive life. This talk highlights some of the sensitivity issues affecting the detectability of terrestrial planets. Sensitivity calculations show that a system consisting of 2 m apertures operating at 5 AU or 4 m apertures operating at 1 AU can detect terrestrial planets in reasonable integration times for levels of exo-zodiacal emission up to 10 times that seen in our solar system (hereafter denoted as 10xSS). Additionally, simulations show that confusion noise from structures in the exo-zodiacal cloud should not impede planet detection until the exo-zodiacal emission reaches the 10xSS level.

  18. Tropical African vegetation change during the early Pliocene

    NASA Astrophysics Data System (ADS)

    Liddy, H.; Sieracki, A.; Feakins, S. J.

    2013-12-01

    The early Pliocene is the most recent period to experience sustained global warmth with similar to modern atmospheric CO2 concentrations (~400ppmV), but the response of terrestrial ecosystems in the tropics to these conditions is poorly understood. Here we explore vegetation change in northeast Africa during the early Pliocene using terrestrial biomarkers in marine sediments from the Gulf of Aden. Plant leaf wax C30 n-alkanoic acid carbon isotopic composition (?13Cwax) spanning 5.3 to 3.8 Ma indicate a trend towards dominance of plants using the C3 (Calvin cycle), reversing the earlier expansion of C4 (Hatch-Slack) biomass in the Miocene. The return to C3 dominance by the mid Pliocene reflects a combination of the possible drivers including more humid conditions controlled by rising western Indian Ocean SSTs and globally elevated atmospheric CO2 levels as well as the direct effects of higher atmospheric CO2 on quantum yields favoring the competitiveness of C3 plants. Intriguingly, high variability is also observed during this period with shifts in ?13Cwax of up to 7‰ on 105 year timescales, presumably linked to local orbital forcing. Taken together, these trends indicate dynamic changes in vegetation that oscillate between more forested and more open grasslands with increasingly more woody cover by the mid Pliocene.

  19. Ozone generation by rock fracture: Earthquake early warning?

    SciTech Connect

    Baragiola, Raul A.; Dukes, Catherine A.; Hedges, Dawn [Engineering Physics, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2011-11-14

    We report the production of up to 10 ppm ozone during crushing and grinding of typical terrestrial crust rocks in air, O{sub 2} and CO{sub 2} at atmospheric pressure, but not in helium or nitrogen. Ozone is formed by exoelectrons emitted by high electric fields, resulting from charge separation during fracture. The results suggest that ground level ozone produced by rock fracture, besides its potential health hazard, can be used for early warning in earthquakes and other catastrophes, such as landslides or land shifts in excavation tunnels and underground mines.

  20. Solar structure and terrestrial weather

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.

    1976-01-01

    The possibility that solar activity has discernible effects on terrestrial weather is considered. Research involving correlation of weather conditions with solar and geomagnetic activity is discussed.

  1. Earth and Terrestrial Planet Formation

    E-print Network

    Jacobson, Seth A

    2015-01-01

    The growth and composition of Earth is a direct consequence of planet formation throughout the Solar System. We discuss the known history of the Solar System, the proposed stages of growth and how the early stages of planet formation may be dominated by pebble growth processes. Pebbles are small bodies whose strong interactions with the nebula gas lead to remarkable new accretion mechanisms for the formation of planetesimals and the growth of planetary embryos. Many of the popular models for the later stages of planet formation are presented. The classical models with the giant planets on fixed orbits are not consistent with the known history of the Solar System, fail to create a high Earth/Mars mass ratio, and, in many cases, are also internally inconsistent. The successful Grand Tack model creates a small Mars, a wet Earth, a realistic asteroid belt and the mass-orbit structure of the terrestrial planets. In the Grand Tack scenario, growth curves for Earth most closely match a Weibull model. The feeding zon...

  2. Siberian Peatlands a Net Carbon Sink and Global Methane Source Since the Early Holocene

    NASA Astrophysics Data System (ADS)

    Smith, L. C.; MacDonald, G. M.; Velichko, A. A.; Beilman, D. W.; Borisova, O. K.; Frey, K. E.; Kremenetski, K. V.; Sheng, Y.

    2004-01-01

    Interpolar methane gradient (IPG) data from ice cores suggest the ``switching on'' of a major Northern Hemisphere methane source in the early Holocene. Extensive data from Russia's West Siberian Lowland show (i) explosive, widespread peatland establishment between 11.5 and 9 thousand years ago, predating comparable development in North America and synchronous with increased atmospheric methane concentrations and IPGs, (ii) larger carbon stocks than previously thought (70.2 Petagrams, up to ~26% of all terrestrial carbon accumulated since the Last Glacial Maximum), and (iii) little evidence for catastrophic oxidation, suggesting the region represents a long-term carbon dioxide sink and global methane source since the early Holocene.

  3. SOLAR PHYSICS AND TERRESTRIAL EFFECTS Solar-Terrestrial Interactions

    E-print Network

    Mojzsis, Stephen J.

    SOLAR PHYSICS AND TERRESTRIAL EFFECTS Chapter 4 Chapter 4 Solar-Terrestrial Interactions from the charged particles that reach the planet steadily as part of the solar wind and the much it will be deflected into a circular or spiral path by the Lorentz Force. Most charged particles in the solar wind

  4. Microbial life in terrestrial permafrost: methanogenesis and nitrification in Gelisols as potentials for exobiological processes

    Microsoft Academic Search

    Dirk Wagner; Eva Spieck; Eberhard Bock; Eva-Maria Pfeiffer

    2002-01-01

    The comparability of environmental and climatic conditions of the early Mars and Earth is of special interest for the actual research in astrobiology. Martian surface and terrestrial permafrost areas show similar morphological structures, which suggests that their development is based on comparable processes. Soil microbial investigations of adaptation strategies of microorganisms from terrestrial permafrost in combination with environmental, geochemical and

  5. A Characterization of the Terrestrial Environment of Kodiak Island, Alaska for the Design, Development and Operation of Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Rawlins, Michael A.; Johnson, Dale L.; Batts, Glen W.

    2000-01-01

    A quantitative characterization of the terrestrial environment is an important component in the success of a launch vehicle program. Environmental factors such as winds, atmospheric thermodynamics, precipitation, fog, and cloud characteristics are among many parameters that must be accurately defined for flight success. The National Aeronautics and Space Administration (NASA) is currently coordinating weather support and performing analysis for the launch of a NASA payload from a new facility located at Kodiak Island, Alaska in late 2001 (NASA, 1999). Following the first launch from the Kodiak Launch Complex, an Air Force intercontinental ballistic missile on November 5, 1999, the site's developer, the Alaska Aerospace Development Corporation (AADC), is hoping to acquire a sizable share of the many launches that will occur over the next decade. One such customer is NASA, which is planning to launch the Vegetation Canopy Lidar satellite aboard an Athena I rocket, the first planned mission to low earth orbit from the new facility. To support this launch, a statistical model of the atmospheric and surface environment for Kodiak Island, AK has been produced from rawinsonde and surface-based meteorological observations for use as an input to future launch vehicle design and/or operations. In this study, the creation of a "reference atmosphere" from rawinsonde observations is described along with comparisons between the reference atmosphere and existing model representations for Kodiak. Meteorological conditions that might result in a delay on launch day (cloud cover, visibility, precipitation, etc.) are also explored and described through probabilities of launch by month and hour of day. This atmospheric "mission analysis" is also useful during the early stages of a vehicle program, when consideration of the climatic characteristics of a location can be factored into vehicle designs. To be most beneficial, terrestrial environment definitions should a) be available at the inception of the program and based on the desired operational performance of the launch vehicle, b) be issued under the signature of the program manager and be part of the controlled program definition and requirements documentation, and c) specify the terrestrial environment for all phases of activity including prelaunch, launch, ascent, on-orbit, decent, and landing. Since the beginning of the space era, NASA has utilized some of the most detailed assessments of the terrestrial climatic environment in design, development, and operations of both expendable and reusable launch vehicles.

  6. The Australian terrestrial carbon budget: preliminary results

    NASA Astrophysics Data System (ADS)

    Canadell, J.; Haverd, V.; Raupach, M. R.; Law, R.; Meyer, M.; Pickett-Heaps, C.

    2010-12-01

    In the context of the REgional Carbon Cycle Assessment and Processes (RECCAP), we will present preliminary results on the mean and variability of the terrestrial carbon budget of Australia for the period 1990-2009. We will attempt to reconcile a number of bottom-up and top-down flux estimates including: (1) net ecosystem production (with attribution to gross primary production and respiration) using 5 land surface models applied globally and 1 model applied regionally at high resolution (CABLE); (2) Land use change fluxes from the Australian National Carbon Accounting System (NCAS); (3) Fire emissions from the Global Fire Emission Database (GFED); and (4) net carbon fluxes between land and atmosphere as seen by a range of CO2 atmospheric inversions. Model outputs will be ranked by their performance against continental and regional observations and weighted accordingly for model averages.

  7. Carbon dioxide efficiency of terrestrial enhanced weathering.

    PubMed

    Moosdorf, Nils; Renforth, Phil; Hartmann, Jens

    2014-05-01

    Terrestrial enhanced weathering, the spreading of ultramafic silicate rock flour to enhance natural weathering rates, has been suggested as part of a strategy to reduce global atmospheric CO2 levels. We budget potential CO2 sequestration against associated CO2 emissions to assess the net CO2 removal of terrestrial enhanced weathering. We combine global spatial data sets of potential source rocks, transport networks, and application areas with associated CO2 emissions in optimistic and pessimistic scenarios. The results show that the choice of source rocks and material comminution technique dominate the CO2 efficiency of enhanced weathering. CO2 emissions from transport amount to on average 0.5-3% of potentially sequestered CO2. The emissions of material mining and application are negligible. After accounting for all emissions, 0.5-1.0 t CO2 can be sequestered on average per tonne of rock, translating into a unit cost from 1.6 to 9.9 GJ per tonne CO2 sequestered by enhanced weathering. However, to control or reduce atmospheric CO2 concentrations substantially with enhanced weathering would require very large amounts of rock. Before enhanced weathering could be applied on large scales, more research is needed to assess weathering rates, potential side effects, social acceptability, and mechanisms of governance. PMID:24597739

  8. 1, 167193, 2004 Terrestrial carbon

    E-print Network

    Paris-Sud XI, Université de

    BGD 1, 167­193, 2004 Terrestrial carbon budget at country-scale I. A. Janssens et al. Title Page Biogeosciences Discussions is the access reviewed discussion forum of Biogeosciences The carbon budget.janssens@ua.ac.be) 167 #12;BGD 1, 167­193, 2004 Terrestrial carbon budget at country-scale I. A. Janssens et al. Title

  9. Accelerated Sequestration of Terrestrial Plant Biomass in the Deep Ocean

    NASA Astrophysics Data System (ADS)

    Strand, S. E.

    2010-12-01

    One of the most efficient uses of aboveground agricultural residues to reduce atmospheric CO2 is burial in sites removed from contact with the atmosphere and in which degradation of lignocellulose is inhibited (Strand and Benford 2009). Similarly by burying forest residues greater benefits for atmospheric carbon accrue compared to incineration or bioethanol production. Accessible planetary sites that are most removed from contact with the atmosphere are primarily the deep ocean sediments. Many deep ocean sediment ecologies are acclimated to massive inputs of terrestrial plant biomass. Nonetheless, marine degradation rates of lignocellulose are slower than terrestrial rates (Keil et al. 2010). Additionally, anaerobic conditions are easily achieved in many deep ocean sediments, inhibiting lignocellulose degradation further, while the dominance of sulfate in the water column as electron acceptor prevents the release of methane from methanogenesis to the atmosphere. The potential benefit of massive removal of excess terrestrial biomass to the deep ocean will be estimated and compared to other uses including biochar and BECS. The impact of the biomass on the marine environment will be discussed and potential sequestration sites in the Gulf of Mexico and the Atlantic compared. Keil, R. G., J. M. Nuwer, et al. (2010). "Burial of agricultural byproducts in the deep sea as a form of carbon sequestration: A preliminary experiment." Marine Chemistry (In Press, online 6 August 2010). Strand, S. E. and G. Benford (2009). "Ocean sequestration of crop residue carbon: recycling fossil fuel carbon back to deep sediments." Environ. Sci. Technol. 43(4): 1000-1007.

  10. Atmospheric Circulation of Exoplanets

    NASA Astrophysics Data System (ADS)

    Showman, A. P.; Cho, J. Y.-K.; Menou, K.

    2010-12-01

    We survey the basic principles of atmospheric dynamics relevant to explaining existing and future observations of exoplanets, both gas giant and terrestrial. Given the paucity of data on exoplanet atmospheres, our approach is to emphasize fundamental principles and insights gained from solar system studies that are likely to be generalizable to exoplanets. We begin by presenting the hierarchy of basic equations used in atmospheric dynamics, including the Navier-Stokes, primitive, shallow-water, and two-dimensional nondivergent models. We then survey key concepts in atmospheric dynamics, including the importance of planetary rotation, the concept of balance, and simple scaling arguments to show how turbulent interactions generally produce large-scale east-west banding on rotating planets. We next turn to issues specific to giant planets, including their expected interior and atmospheric thermal structures, the implications for their wind patterns, and mechanisms to pump their east-west jets. Hot Jupiter atmospheric dynamics are given particular attention, as these close-in planets have been the subject of most of the concrete developments in the study of exoplanetary atmospheres. We then turn to the basic elements of circulation on terrestrial planets as inferred from solar system studies, including Hadley cells, jet streams, processes that govern the large-scale horizontal temperature contrasts, and climate, and we discuss how these insights may apply to terrestrial exoplanets. Although exoplanets surely possess a greater diversity of circulation regimes than seen on the planets in our solar system, our guiding philosophy is that the multidecade study of solar system planets reviewed here provides a foundation upon which our understanding of more exotic exoplanetary meteorology must build.

  11. The Oldest Caseid Synapsid from the Late Pennsylvanian of Kansas, and the Evolution of Herbivory in Terrestrial Vertebrates

    PubMed Central

    Reisz, Robert R.; Fröbisch, Jörg

    2014-01-01

    The origin and early evolution of amniotes (fully terrestrial vertebrates) led to major changes in the structure and hierarchy of terrestrial ecosystems. The first appearance of herbivores played a pivotal role in this transformation. After an early bifurcation into Reptilia and Synapsida (including mammals) 315 Ma, synapsids dominated Paleozoic terrestrial vertebrate communities, with the herbivorous caseids representing the largest vertebrates on land. Eocasea martini gen. et sp. nov., a small carnivorous caseid from the Late Carboniferous, extends significantly the fossil record of Caseidae, and permits the first clade-based study of the origin and initial evolution of herbivory in terrestrial tetrapods. Our results demonstrate for the first time that large caseid herbivores evolved from small, non-herbivorous caseids. This pattern is mirrored by three other clades, documenting multiple, independent, but temporally staggered origins of herbivory and increase in body size among early terrestrial tetrapods, leading to patterns consistent with modern terrestrial ecosystem. PMID:24739998

  12. Evolution of the Atmosphere and Climate of Venus

    NASA Astrophysics Data System (ADS)

    Grinspoon, D.; Bullock, M.

    2014-04-01

    We will review the evolution of the atmosphere and climate of Venus, with a focus on the apparent divergence from early more Earth-like conditions. We will examine what constraints can be put on the nature and timing of this divergence, and in particular on the history and role of water in affecting the evolution of Venus. Venus, in comparison with Earth, is strikingly dry. As our understanding of terrestrial planet evolution has increased, the importance of water abundance as a substance controlling many evolutionary factors has become increasingly clear. This is true of biological evolution, as the presence of liquid water is widely regarded as the key to the possibility of finding "life as we know it" on other worlds. It is also true of geological and climatic evolution. Water is among the most important climatically active atmospheric gasses on the terrestrial planets. It is also a controlling variable for tectonic style and geologic processes, as well as a mediator of surfaceatmosphere chemical reactions. First, we will discuss what is known about the accretion process, the initial conditions of a primordial Venusian atmosphere, and how the differing history of late large impacts (lack of a moon-forming impact, or combination of large impacts that largely cancelled angular momentum) may have affected these initial conditions. Then we will review what is known about atmospheric loss processes and in particular the constraints on loss of water over time. The current state of modeling of the runaway or moist greenhouse will be reviewed, in the context of recent work trying to establish theoretical limits for the inner radius of the circumstellar habitable zone and its movement with stellar evolution. The coupling between of geological and tectonic evolution and the atmosphere and climate will be reviewed, including climate feedbacks, which are operating today, depending on the level of current geological activity. Finally we will discuss the prospects for improving constraints on the atmospheric and climatic evolution of Venus with measurements made by future missions.

  13. ORIGINS OF NON-MASS-DEPENDENT FRACTIONATION OF EXTRA-TERRESTRIAL OXYGEN

    SciTech Connect

    Barcena, Homar; Connolly, Harold C. [Department of Physical Sciences, Kingsborough Community College of the City University of New York, 2001 Oriental Boulevard, Brooklyn, NY 11235 (United States)

    2012-08-01

    The distribution of oxygen isotopes in meteorites and within the earliest solids that formed in the solar system hints that the precursors of these materials must have undergone a mass-independent process. The mass-independent process is specifically one that fractionates {sup 16}O from {sup 17}O and {sup 18}O. This chemical signature is indicative of non-equilibrium processing, which bear resemblance to some unusual terrestrial phenomenon such as fractionation of ozone in the upper Earth atmosphere. That the mass-independent fractionation of oxygen isotopes is preserved within petrological records presents planetary scientists interesting clues to the events that may have occurred during the formation of the solar system. Currently, there are several hypotheses on the origins of the oxygen isotope distribution within primitive planetary materials, which include both thermal and photochemical models. We present a new model based on a physico-chemical hypothesis for the origin of non-mass-dependent O-isotope distribution in oxygen-bearing extra-terrestrial materials, which originated from the disproportionation of CO in dark molecular clouds to create CO{sub 2} reservoirs. The disproportionation created a reservoir of heavy oxygen isotopes and could have occurred throughout the evolution of the disk. The CO{sub 2} was a carrier of the isotope anomaly in the solar nebula and we propose that non-steady-state mixing of these reservoirs with the early rock-forming materials during their formation corresponds with the birth and evolution of the solar system.

  14. Planetary habitability: lessons learned from terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Preston, Louisa J.; Dartnell, Lewis R.

    2014-01-01

    Terrestrial analogue studies underpin almost all planetary missions and their use is essential in the exploration of our Solar system and in assessing the habitability of other worlds. Their value relies on the similarity of the analogue to its target, either in terms of their mineralogical or geochemical context, or current physical or chemical environmental conditions. Such analogue sites offer critical ground-truthing for astrobiological studies on the habitability of different environmental parameter sets, the biological mechanisms for survival in extreme environments and the preservation potential and detectability of biosignatures. The 33 analogue sites discussed in this review have been selected on the basis of their congruence to particular extraterrestrial locations. Terrestrial field sites that have been used most often in the literature, as well as some lesser known ones which require greater study, are incorporated to inform on the astrobiological potential of Venus, Mars, Europa, Enceladus and Titan. For example, the possibility of an aerial habitable zone on Venus has been hypothesized based on studies of life at high-altitudes in the terrestrial atmosphere. We also demonstrate why many different terrestrial analogue sites are required to satisfactorily assess the habitability of the changing environmental conditions throughout Martian history, and recommend particular sites for different epochs or potential niches. Finally, habitable zones within the aqueous environments of the icy moons of Europa and Enceladus and potentially in the hydrocarbon lakes of Titan are discussed and suitable analogue sites proposed. It is clear from this review that a number of terrestrial analogue sites can be applied to multiple planetary bodies, thereby increasing their value for astrobiological exploration. For each analogue site considered here, we summarize the pertinent physiochemical environmental features they offer and critically assess the fidelity with which they emulate their intended target locale. We also outline key issues associated with the existing documentation of analogue research and the constraints this has on the efficiency of discoveries in this field. This review thus highlights the need for a global open access database for planetary analogues.

  15. Plant Nitrogen Uptake in Terrestrial Biogeochemical Models

    NASA Astrophysics Data System (ADS)

    Marti Donati, A.; Cox, P.; Smith, M. J.; Purves, D.; Sitch, S.; Jones, C. D.

    2013-12-01

    Most terrestrial biogeochemical models featured in the last Intergovernmental Panel on Climate Change (IPPC) Assessment Report highlight the importance of the terrestrial Carbon sequestration and feedbacks between the terrestrial Carbon cycle and the climate system. However, these models have been criticized for overestimating predicted Carbon sequestration and its potential climate feedback when calculating the rate of future climate change because they do not account for the Carbon sequestration constraints caused by nutrient limitation, particularly Nitrogen (N). This is particularly relevant considering the existence of a substantial deficit of Nitrogen for plants in most areas of the world. To date, most climate models assume that plants have access to as much Nitrogen as needed, but ignore the nutrient requirements for new vegetation growth. Determining the natural demand and acquisition for Nitrogen and its associated resource optimization is key when accounting for the Carbon sequestration constrains caused by nutrient limitation. The few climate models that include C-N dynamics have illustrated that the stimulation of plant growth over the coming century may be significantly smaller than previously predicted. However, models exhibit wide differences in their predictive accuracy and lead to widely diverging and inconsistent projections accounting for an uncertain Carbon sequestration decrease due to Nitrogen limitation ranging from 7 to 64%. This reduction in growth is partially offset by an increase in the availability of nutrients resulting from an accelerated rate of decomposition of dead plants and other organic matter that occurring with a rise in temperature. However, this offset does not counterbalance the reduced level of plant growth calculated by natural nutrient limitations. Additionally, Nitrogen limitation is also expected to become more pronounced in some ecosystems as atmospheric CO2 concentration increases; resulting in less new growth and higher atmospheric CO2 concentrations than originally expected. This study compares the differences in the predictions of alternative models of plant N uptake found in different terrestrial biogeochemical models with the predictions from a new N-uptake model developed under the Joint UK Land Environment Simulator (JULES) framework. We implement a methodology for the construction, parameterization and evaluation of N uptake models to fully decompose all the N uptake component processes in terms of their parameter uncertainty and the accuracy of their predictions with respect to different empirical data sets. Acknowledgements This work has been funded by the European Commission FP7-PEOPLE-ITN-2008 Marie Curie Action: "Greencycles II: FP7-PEOPLE-ITN-2008 Marie Curie Action: "Networks for Initial Training"

  16. Plant Nitrogen Uptake in Terrestrial Biogeochemical Models

    NASA Astrophysics Data System (ADS)

    Marti, Alejandro; Cox, Peter; Sitch, Stephen; Jones, Chris; Liddicoat, spencer

    2013-04-01

    Most terrestrial biogeochemical models featured in the last Intergovernmental Panel on Climate Change (IPPC) Assessment Report highlight the importance of the terrestrial Carbon sequestration and feedbacks between the terrestrial Carbon cycle and the climate system. However, these models have been criticized for overestimating predicted Carbon sequestration and its potential climate feedback when calculating the rate of future climate change because they do not account for the Carbon sequestration constraints caused by nutrient limitation, particularly Nitrogen (N). This is particularly relevant considering the existence of a substantial deficit of Nitrogen for plants in most areas of the world. To date, most climate models assume that plants have access to as much Nitrogen as needed, but ignore the nutrient requirements for new vegetation growth. Determining the natural demand and acquisition for Nitrogen and its associated resource optimization is key when accounting for the Carbon sequestration constrains caused by nutrient limitation. The few climate models that include C-N dynamics have illustrated that the stimulation of plant growth over the coming century may be two to three times smaller than previously predicted. This reduction in growth is partially offset by an increase in the availability of nutrients resulting from an accelerated rate of decomposition of dead plants and other organic matter that occurring with a rise in temperature. However, this offset does not counterbalance the reduced level of plant growth calculated by natural nutrient limitations. Additionally, Nitrogen limitation is also expected to become more pronounced in some ecosystems as atmospheric CO2 concentration increases; resulting in less new growth and higher atmospheric CO2 concentrations than originally expected. This study compares alternative models of plant N uptake as found in different terrestrial biogeochemical models against field measurements, and introduces a new N-uptake model to the Joint UK Land Environment Simulator (JULES).. Acknowledgements This work has been funded by the European Commission FP7-PEOPLE-ITN-2008 Marie Curie Action: "Greencycles II: FP7-PEOPLE-ITN-2008 Marie Curie Action: "Networks for Initial Training"

  17. Early Eocene's climate and ocean circulation from coupled model simulations

    NASA Astrophysics Data System (ADS)

    Weber, Tobias; Thomas, Maik

    2014-05-01

    While proxy data provide a snapshot of climate conditions at a specific location, coupled atmosphere-ocean models are able to expand this knowledge over the globe. Therefore, they are indispensable tools for understanding past climate conditions. We model the dynamical state of atmosphere and ocean during the Early Eocene and pre-industrial times, using the coupled atmosphere-ocean model ECHAM5/MPIOM with realistic reconstructions of vegetation and CO2. The resulting simulated climate variables are compared to terrestrial and oceanic proxies. The Early Eocene climate is in the global mean warmer (~13°C) and wetter (~1 mm/d) than in pre-industrial times. Especially temperatures in the Southern Ocean, the Greenland Sea and Arctic Ocean raise by up to 25K, being in accordance with surface temperature estimates from terrestrial and marine proxy data. The oceans are hereby rendered ice-free, leading to a decrease of polar albedo and thereby facilitating polar warming. This leads to a by 5K diminished equator-to-pole temperature gradient. Warmer temperatures as well as changed bathymetry have an effect on ocean dynamics in the Early Eocene. Although deep-water formation can be found in the Greenland Sea, Weddell Sea, and Tethys Sea, it is weaker than in the pre-industrial run and the resulting circulation is shallower. This is not only visible in water transport through sea gates but also in the Atlantic Meridional Overturning Circulation (AMOC), adopting its maximum at 700m depths in the Early Eocene, while maximum transport is reached in the pre-industrial control run at 1200m. Albeit a shallow and weak thermohaline circulation, a global ocean conveyor belt is being triggered, causing a transport from the areas of subduction through the Atlantic and Southern Oceans into the Indian and Pacific Oceans.

  18. Possible cometary origin of heavy noble gases in the atmospheres of Venus, Earth and Mars

    PubMed

    Owen, T; Bar-Nun, A; Kleinfeld, I

    1992-07-01

    Models that trace the origin of noble gases in the atmospheres of the terrestrial planets (Venus, Earth and Mars) to the 'planetary component' in chondritic meteorites confront several problems. The 'missing' xenon in the atmospheres of Mars and Earth is one of the most obvious; this gas is not hidden or trapped in surface materials. On Venus, the absolute abundances of neon and argon per gram of rock are higher even than those in carbonaceous chondrites, whereas the relative abundances of argon and krypton are closer to solar than to chondritic values (there is only an upper limit on xenon). Pepin has developed a model that emphasizes hydrodynamic escape of early, massive hydrogen atmospheres to explain the abundances and isotope ratios of noble gases on all three planets. We have previously suggested that the unusual abundances of heavy noble gases on Venus might be explained by the impact of a low-temperature comet. Further consideration of the probable history of the martian atmosphere, the noble-gas data from the (Mars-derived) SNC meteorites and laboratory experiments on the trapping of noble gases in ice lead us to propose here that the noble gases in the atmospheres of all of the terrestrial planets are dominated by a mixture of an internal component and contribution from impacting icy planetesimals (comets). If true, this hypothesis illustrates the importance of impacts in determining the volatile inventories of these planets. PMID:11536499

  19. Deciphering thermal phase curves of tidally locked terrestrial planets

    NASA Astrophysics Data System (ADS)

    Koll, Daniel D. B.; Abbot, Dorian S.

    2015-01-01

    Next-generation space telescopes will allow us to characterize terrestrial exoplanets. To do so effectively it will be crucial to make use of all available data. We therefore investigate which atmospheric properties can, and cannot, be inferred from a tidally locked planet's broadband thermal phase curve. First, we use dimensional analysis to show that phase curves are controlled by six nondimensional parameters. Second, we use an idealized general circulation model (GCM) to explore the relative sensitivity of phase curves to these parameters. We find that the feature of phase curves most sensitive to its atmospheric parameters is the peak-to-trough amplitude. Moreover, except for hot and rapidly rotating planets, the phase amplitude is primarily sensitive to only two nondimensional parameters: 1) the ratio of dynamical to radiative timescales, and 2) the longwave optical thickness at the surface. As an application of this technique, we show how phase curve measurements could be combined with transit or emission spectroscopy to constrain the surface pressure and atmospheric mass of terrestrial planets. Such constraints will be important for studying the atmospheric evolution of terrestrial exoplanets, and for characterizing the surface conditions on habitable planets.

  20. Utility terrestrial biodiversity issues

    SciTech Connect

    Breece, G.A. [Southern Company, Atlanta, GA (United States); Ward, B.J. [Carolina Power and Light Company, Raleigh, NC (United States)

    1996-11-01

    Results from a survey of power utility biologists indicate that terrestrial biodiversity is considered a major issued by only a few utilities; however, a majority believe it may be a future issue. Over half of the respondents indicated that their company is involved in some management for biodiversity, and nearly all feel that it should be a goal for resource management. Only a few utilities are funding biodiversity research, but a majority felt more research was needed. Generally, larger utilities with extensive land holdings had greater opportunities and resources for biodiversity management. Biodiversity will most likely be a concern with transmission rights-of-way construction and maintenance, endangered species issues and general land resource management, including mining reclamation and hydro relicensing commitments. Over half of the companies surveyed have established voluntary partnerships with management groups, and biodiversity is a goal in nearly all the joint projects. Endangered species management and protection, prevention of forest fragmentation, wetland protection, and habitat creation and protection are the most common partnerships involving utility companies. Common management practices and unique approaches are presented, along with details of the survey. 4 refs.

  1. Combined terrestrial and marine biomarker records from an Icelandic fjord: insights into Holocene climate drivers and marine/ terrestrial responses

    NASA Astrophysics Data System (ADS)

    Moossen, H. M.; Seki, O.; Quillmann, U.; Andrews, J. T.; Bendle, J. A.

    2012-12-01

    Holocene climate change has affected human cultures throughout at least the last 4000 years (D'Andrea et al., 2011). Today, studying Holocene climate variability is important, both to constrain the influence of climate change on ancient cultures and to place contemporary climate change in a historic context. Organic geochemical biomarkers are an ideal tool to study how climatic changes have affected terrestrial and marine ecosystems, as a host of different biomarker based climate proxies have emerged over recent years. Applying the available biomarker proxies on sediment cores from fjordic environments facilitates the study of how climate has affected terrestrial and marine ecosystems, and how these ecosystems have interacted. Ìsafjardardjúp fjord in Northwest Iceland is an ideal location to study North Atlantic Holocene climate change because the area is very sensitive to changes in the oceanic and atmospheric current systems (Hurrell, 1995; Quillmann et al., 2010). In this study we present high resolution (1 sample/30 calibrated years) terrestrial and marine biomarker records from a 38 m sediment core from Ìsafjardardjúp fjord covering the Holocene. We reconstruct sea surface temperature variations using the alkenone derived UK'37 proxy. Air temperature changes are reconstructed using the GDGT derived MBT/CBT palaeothermometer. We use the average chain length (ACL) variability of n-alkanes derived from terrestrial higher plant leaf waxes to reconstruct changing precipitation regimes. The relationship between ACL and precipitation is confirmed by comparing it with the ?D signature of the C29 n-alkane and soil pH changes inferred by the CBT proxy. The combined sea surface and air temperature and precipitation records indicate that different climate changing drivers were dominant at different stages of the Holocene. Sea surface temperatures were strongly influenced by the melting of the remaining glaciers from the last glacial maximum throughout the early Holocene, while air temperatures were influenced by high solar insolation. The central Holocene climate is mainly driven by decreasing northern hemisphere insolation, while the lateral transport of energy from the equator into the North Atlantic region drives climate change in the late Holocene. D'Andrea, W.J., Huang, Y., Fritz, S.C., Anderson, N.J., (2011) Abrupt Holocene climate change as an important factor for human migration in West Greenland. Proceedings of the National Academy of Sciences of the United States of America, 108(24), 9765-9769. Hurrell, J.W., (1995) Decadal trends in the North Atlantic Oscillation - Regional temperatures and precipitation. Science, 269(5224), 676-679. Quillmann, U., Jennings, A., Andrews, J., (2010) Reconstructing Holocene palaeoclimate and palaeoceanography in Isafjaroardjup, northwest Iceland, from two fjord records overprinted by relative sea-level and local hydrographic changes. Journal of Quaternary Science, 25(7), 1144-1159.

  2. Contaminant Exposure in Terrestrial Vertebrates

    EPA Science Inventory

    Manuscript is a critical review of the state of the science for quantifying exposures of terrestrial wildlife species to chemical contamination. It describes the unique aspects of birds, mammals, reptiles, amphibians and threatened and endangered species. Fate and transport of ...

  3. USING TERRESTRIAL PLANTS IN BIOMONITORING

    EPA Science Inventory

    Terrestrial plants have been used as monitors of environmental pollutants since at least the beginning of this century & have recently received attention in response to the need for ecological assessments at hazardous waste sites & monitoring pesticide damage to nontarget plants....

  4. Radiocarbon dating of terrestrial carbonates

    USGS Publications Warehouse

    Pigati, Jeffrey S.

    2014-01-01

    Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

  5. GEOLogic: Terrestrial and Jovian Planets

    NSDL National Science Digital Library

    Laura Guertin

    In this two-part example, students are given clues about properties about the terrestrial and Jovian planets respectively and asked to match up the planet with the correct equatorial radius, mean orbital velocity, and period of rotation.

  6. Isoprene emission from terrestrial ecosystems in response to