Sample records for early terrestrial atmosphere

  1. A comparative study of the early terrestrial atmospheres

    NASA Astrophysics Data System (ADS)

    Durham, R.; Chamberlain, J. W.

    1989-01-01

    The CO2 abundance required for maintenance of the climatic conditions speculated to have existed 4 billion years ago on the earth, Mars, and Venus is presently sought by means of a one-dimensional radiative-convective atmospheric model. It is ascertained on this basis that the terrestrial and Martian atmospheres were highly stable, and unlikely to proceed to a moist or runaway greenhouse state even if CO2 partial pressure were equivalent to 100 bars on earth. The proximity of Venus to the sun rendered its atmosphere highly susceptible to rapid water vapor photodissociation and hydrogen escape.

  2. Evolution of Terrestrial Atmospheres

    NSDL National Science Digital Library

    O'Connell, Robert W.

    This lecture compares terrestrial atmospheres as well as discusses atmospheric processes, atmospheric equilibrium, and the atmospheric development of Mars, Venus, and Earth. It ends with a discussion of natural and unnatural climatic changes.

  3. Atmospheric oxygen levels affect mudskipper terrestrial performance: implications for early tetrapods.

    PubMed

    Jew, Corey J; Wegner, Nicholas C; Yanagitsuru, Yuzo; Tresguerres, Martin; Graham, Jeffrey B

    2013-08-01

    The Japanese mudskipper (Periophthalmus modestus), an amphibious fish that possesses many respiratory and locomotive specializations for sojourns onto land, was used as a model to study how changing atmospheric oxygen concentrations during the middle and late Paleozoic Era (400-250 million years ago) may have influenced the emergence and subsequent radiation of the first tetrapods. The effects of different atmospheric oxygen concentrations (hyperoxia = 35%, normoxia = 21%, and hypoxia = 7% O2) on terrestrial performance were tested during exercise on a terrestrial treadmill and during recovery from exhaustive exercise. Endurance and elevated post-exercise oxygen consumption (EPOC; the immediate O2 debt repaid post-exercise) correlated with atmospheric oxygen concentration indicating that when additional oxygen is available P. modestus can increase oxygen utilization both during and following exercise. The time required post-exercise for mudskippers to return to a resting metabolic rate did not differ between treatments. However, in normoxia, oxygen consumption increased above hyperoxic values 13-20 h post-exercise suggesting a delayed repayment of the incurred oxygen debt. Finally, following exercise, ventilatory movements associated with buccopharyngeal aerial respiration returned to their rest-like pattern more quickly at higher concentrations of oxygen. Taken together, the results of this study show that P. modestus can exercise longer and recover quicker under higher oxygen concentrations. Similarities between P. modestus and early tetrapods suggest that increasing atmospheric oxygen levels during the middle and late Paleozoic allowed for elevated aerobic capacity and improved terrestrial performance, and likely led to an accelerated diversification and expansion of vertebrate life into the terrestrial biosphere. PMID:23620255

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

    E-print Network

    Walter, Frederick M.

    ? ­ Smaller planet mass? ­ Lightweight gases? #12;Venus and the Runaway GreenhouseTerrestrial Planet Atmospheres. II. #12;The Moon's Sodium Atmosphere #12;Mercury for a Planet · Equator heated more than poles · Hadley cell transport heat poleward

  5. Atmospheric Circulation of Terrestrial Exoplanets

    E-print Network

    Showman, Adam P; Merlis, Timothy M; Kaspi, Yohai

    2013-01-01

    The investigation of planets around other stars began with the study of gas giants, but is now extending to the discovery and characterization of super-Earths and terrestrial planets. Motivated by this observational tide, we survey the basic dynamical principles governing the atmospheric circulation of terrestrial exoplanets, and discuss the interaction of their circulation with the hydrological cycle and global-scale climate feedbacks. Terrestrial exoplanets occupy a wide range of physical and dynamical conditions, only a small fraction of which have yet been explored in detail. Our approach is to lay out the fundamental dynamical principles governing the atmospheric circulation on terrestrial planets--broadly defined--and show how they can provide a foundation for understanding the atmospheric behavior of these worlds. We first survey basic atmospheric dynamics, including the role of geostrophy, baroclinic instabilities, and jets in the strongly rotating regime (the "extratropics") and the role of the Hadle...

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

    NASA Technical Reports Server (NTRS)

    Schindler, T. L.; Kasting, J. F.

    2000-01-01

    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.

  7. 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

  8. Evidence in pre 2.2 Ga paleosols for the early evolution of atmospheric oxygen and terrestrial biota

    Microsoft Academic Search

    Hiroshi Ohmoto

    1996-01-01

    The loss of Fe from some pre 2.2 Ga paleosols has been considered by previous investigators as the best evidence for a reduced atmosphere prior to 2.2 Ga. I have examined the behavior of Fe in both pre and post 2.2 Ga paleosols from depth profiles of Fe3+Ti, Fe2+Ti, and SigmaFe\\/Ti ratios, and Fe3+Ti vs. Fe2+Ti plots. This new approach

  9. Early Formation of Terrestrial Crust

    NASA Astrophysics Data System (ADS)

    Harrison, T. M.; Schmitt, A. K.; McCulloch, M. T.; Lovera, O. M.

    2007-12-01

    Early (?4.5 Ga) Formation of Terrestrial Crust T.M. Harrison1, A.K. Schmitt1, M.T. McCulloch2, and O.M. Lovera1 1Department of Earth and Space Sciences and IGPP, UCLA, Los Angeles, CA 90095, USA; 2Research School of Earth Sciences, Australian National University, Canberra, A.C.T. 2601 AUSTRALIA Large deviations in ?repsilonHf(T) from bulk silicate Earth seen in >4 Ga detrital zircons from Jack Hills, Western Australia, have been interpreted as reflecting a major differentiation of the silicate Earth at ca. 4.4 to 4.5 Ga. We have expanded the characterization of 176Hf/177Hf (Hf) in Hadean zircons by acquiring a further 116 laser ablation Lu-Hf measurements on 87 grains with ion microprobe 207Pb/206Pb ages up to 4.36 Ga. Most measurements employed concurrent Lu-Hf and 207Pb/206Pb analyses, permitting assessment of the use of ion microprobe data to characterize the age of the volumetrically larger domain sampled by laser drilling. Our new results confirm and extend the earlier observation of significant negative deviations in ?repsilonHf(T) throughout the Hadean, although no positive ?repsilonHf(T) values were documented in this study. These data yields an essentially uniform spectrum of single-stage model ages between 4.54 and 4.20 Ga for extraction of the zircons' protoliths from a chondritic reservoir. We derived the full error propagation expression for a parameter, ?repsilono, which measures the difference of a sample from solar system initial (Hf) (Hfo), and from this conclude that data plotting close to (Hfo), are statistically meaningful and consistent with silicate differentiation at 4.540±0.006 Ga. ?18O and Ti thermometry for these Hadean zircons show little obvious correlation with initial (Hf), consistent with their derivation through fusion of a broad suite of crustal rock types under near water-saturated conditions. Together with the inclusion assemblage and other isotopic and trace element data obtained from these ancient zircons, our results indicate essentially continuous derivation of crust from the mantle from 4.5 to 4.2 Ga, concurrent with recycling into the mantle and internal crustal re-working. These results represent further evidence that by 4.35 Ga, portions of the crust had taken on continental characteristics.

  10. Were early pterosaurs inept terrestrial locomotors?

    PubMed Central

    2015-01-01

    Pterodactyloid pterosaurs are widely interpreted as terrestrially competent, erect-limbed quadrupeds, but the terrestrial capabilities of non-pterodactyloids are largely thought to have been poor. This is commonly justified by the absence of a non-pterodactyloid footprint record, suggestions that the expansive uropatagia common to early pterosaurs would restrict hindlimb motion in walking or running, and the presence of sprawling forelimbs in some species. Here, these arguments are re-visited and mostly found problematic. Restriction of limb mobility is not a problem faced by extant animals with extensive fight membranes, including species which routinely utilise terrestrial locomotion. The absence of non-pterodactyloid footprints is not necessarily tied to functional or biomechanical constraints. As with other fully terrestrial clades with poor ichnological records, biases in behaviour, preservation, sampling and interpretation likely contribute to the deficit of early pterosaur ichnites. Suggestions that non-pterodactyloids have slender, mechanically weak limbs are demonstrably countered by the proportionally long and robust limbs of many Triassic and Jurassic species. Novel assessments of pterosaur forelimb anatomies conflict with notions that all non-pterodactyloids were obligated to sprawling forelimb postures. Sprawling forelimbs seem appropriate for species with ventrally-restricted glenoid articulations (seemingly occurring in rhamphorhynchines and campylognathoidids). However, some early pterosaurs, such as Dimorphodon macronyx and wukongopterids, have glenoid arthrologies which are not ventrally restricted, and their distal humeri resemble those of pterodactyloids. It seems fully erect forelimb stances were possible in these pterosaurs, and may be probable given proposed correlation between pterodactyloid-like distal humeral morphology and forces incurred through erect forelimb postures. Further indications of terrestrial habits include antungual sesamoids, which occur in the manus and pes anatomy of many early pterosaur species, and only occur elsewhere in terrestrial reptiles, possibly developing through frequent interactions of large claws with firm substrates. It is argued that characteristics possibly associated with terrestriality are deeply nested within Pterosauria and not restricted to Pterodactyloidea as previously thought, and that pterodactyloid-like levels of terrestrial competency may have been possible in at least some early pterosaurs. PMID:26157605

  11. Earth's early atmosphere.

    PubMed

    Kasting, J F

    1993-02-12

    Ideas about atmospheric composition and climate on the early Earth have evolved considerably over the last 30 years, but many uncertainties still remain. It is generally agreed that the atmosphere contained little or no free oxygen initially and that oxygen concentrations increased markedly near 2.0 billion years ago, but the precise timing of and reasons for its rise remain unexplained. Likewise, it is usually conceded that the atmospheric greenhouse effect must have been higher in the past to offset reduced solar luminosity, but the levels of atmospheric carbon dioxide and other greenhouse gases required remain speculative. A better understanding of past atmospheric evolution is important to understanding the evolution of life and to predicting whether Earth-like planets might exist elsewhere in the galaxy. PMID:11536547

  12. Atmospheric evolution of the terrestrial planets

    SciTech Connect

    Hunten, D.M. (Univ. of Arizona, Tucson (United States))

    1993-02-12

    The major atmospheric gases on Earth, Venus, and Mars were probably CO[sub 2], H[sub 2]O, and N[sub 2]. Most of the Earth's CO[sub 2] is tied up in minerals such as limestone, and Venus has lost most of its H[sub 2]O, leaving the CO[sub 2] in the atmosphere. Much of Mars' atmosphere may have been eroded in impacts by large meteoroids early in solar-system history. Noble gases are very underabundant everywhere, and must have been lost during an early period; they were probably dragged along during rapid loss of massive amounts of hydrogen. The tenuous atmospheres of Mercury and the moon have lifetimes of a few days or less and must be continuously replenished from internal or external sources.

  13. 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

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

    NASA Technical Reports Server (NTRS)

    Kharchenko, Vasili

    2003-01-01

    We have investigated the energy distributions of the metastable oxygen atoms in the terrestrial thermosphere. Nascent O(lD) atoms play a fundamental role in the energy balance and chemistry of the terrestrial atmosphere, because they are produced by photo-chemical reactions in the excited electronic states and carry significant translational energies.

  15. A New Photochemistry Code for Terrestrial Exoplanet Atmospheres

    E-print Network

    Johnson, Robert E.

    A New Photochemistry Code for Terrestrial Exoplanet Atmospheres Renyu Hu, Sara Seager Massachusetts Institute of Technology Renyu Hu, 2012, UVa Workshop Page 1 #12;Photochemistry Model · 1-D chemistry

  16. 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 ...

  17. Rare earth element systematics of the chemically precipitated component in Early Precambrian iron formations and the evolution of the terrestrial atmosphere-hydrosphere-lithosphere system

    SciTech Connect

    Bau, M.; Moeller, P. (Hahn-Meitner-Institut, Berlin (Germany))

    1993-05-01

    The chemically precipitated component in Early Precambrian (> 2.3 Ga) iron formations (IFs) displays (Sm/Yb)[sub CN] < 1 and (Eu/Sm)[sub SN] > 1 which reflects the corresponding ratios of contemporaneous seawater. In conjunction with [epsilon][sub Nd-IF] > [epsilon][sub Nd-shale] this rare earth element (REE) signature reveals that the REE distribution in Early Precambrian IFs must be explained by mixing between a marine bottom and a surface water component, and that the REEs (and by analogy the Fe) cannot be derived from weathering of a continental source. Mixing calculations reveal that (Sm/Yb)[sub CN] in Early Precambrian marine surface waters was significantly lower than it is today. To explain this difference, two mechanisms are discussed on the basis of higher P[sub CO[sub 2

  18. 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.

  19. 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.

  20. 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

  1. Habitability of Terrestrial Planets in the Early Solar System

    NASA Astrophysics Data System (ADS)

    SLEEP, N. H.

    2001-12-01

    The Protoearth, Mars, Venus, and the Moon-forming impactor were potentially habitable in the early solar system. The interiors of larger asteroids had habitable circulating water. To see when the inner solar system became continuously habitable, one needs to consider the most dangerous events and the safest refugia from them. Early geochemical and accretionary processes set the subsequent silicate planet reservoirs and hence hydrospheric and atmospheric masses. The moon-forming impact made the Moon and the Earth sterile bodies. Following the impact, the Earth passed through a rock-vapor atmosphere on the scale of 1000s of years and an internally heated steam greenhouse on the scale of 2 m.y. Minerals bearing the principle volatiles (water, Cl, and CO2) were stable at the Earth's surface by the time it cooled to 800K. The mass of reactable shallow material was insufficient to contain the available water and CO2. Habitable conditions were established after CO2 could be deeply subducted into the mantle. Vast quantities of H2 were vented during accretion and after the moon-forming impact and eventually lost to space. It is unknown whether significant amounts of this gas were present when the Earth's surface cooled into the habitable range. The moon remained sterile because its interior is essentially devoid of water. The mantle of the Earth, in contrast, cannot hold the available water, leaving the excess to form oceans. Nitrogen may behave similarly with the excess going into the air. Impacts of large asteroids (and comets) were an ever-present danger on otherwise habitable planets. The safest niche on planets was kilometer or deeper crustal rocks habitable by thermophiles. It is inevitable that several objects, which would have left only thermophile survivors, struck the Earth. Such events were so infrequent that the conditions of such a bottleneck should not be confused with conditions for the origin of life. An alternative refugium involves ejection of life within rock fragments and return of such fragments to the surface of the home planet or transfer to another habitable planet. Mars and the larger asteroids were habitable first and provide likely sources of seed and also testable places to look for preserved evidence. Extant terrestrial life appears to have passed through thermophile bottlenecks. There are subtle hints of space transfer. The need of extant life for Ni may be a vestige of life on a young planet covered with ultramafic rocks.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Bubble stability in vigorous convection: Ramifications for magma-ocean degassing and formation of an early atmosphere

    Microsoft Academic Search

    J. Sethian; J. Suckale; L. T. Elkins-Tanton

    2009-01-01

    The heat provided by energetic impacts, radioactive decay and core formation during the early stages in terrestrial planet evolution is sufficient to melt a silicate mantle partially or entirely. Thus, magma-ocean models provide an interesting hypothetical starting point for understanding mantle evolution of terrestrial planets. A key constraint in these models is the formation of an early atmosphere, because it

  7. Photochemistry in Terrestrial Exoplanet Atmospheres II: H2S and SO2 Photochemistry in Anoxic Atmospheres

    E-print Network

    Hu, Renyu; Bains, William

    2013-01-01

    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., H2S and SO2) 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 H2S and SO2 are chemically short-lived in virtually all types of atmospheres on terrestrial exoplanets, based on models of H2, N2, and CO2 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 element...

  8. Water loss from terrestrial planets with CO{sub 2}-rich atmospheres

    SciTech Connect

    Wordsworth, R. D.; Pierrehumbert, R. T., E-mail: rwordsworth@uchicago.edu [Department of the Geophysical Sciences, University of Chicago, 60637 IL (United States)

    2013-12-01

    Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on a range of atmospheric and external parameters. We show that CO{sub 2} can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO{sub 2} atmospheric partial pressures (0.1-1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but X-ray and ultraviolet/ultravoilet luminosity decreases, this places strong limits on water loss for planets like Earth. In contrast, for a CO{sub 2}-rich early Venus, diffusion limits on water loss are only important if clouds caused strong cooling, implying that scenarios where the planet never had surface liquid water are indeed plausible. Around M-stars, water loss is primarily a function of orbital distance, with planets that absorb less flux than ?270 W m{sup –2} (global mean) unlikely to lose more than one Earth ocean of H{sub 2}O over their lifetimes unless they lose all their atmospheric N{sub 2}/CO{sub 2} early on. Because of the variability of H{sub 2}O delivery during accretion, our results suggest that many 'Earth-like' exoplanets in the habitable zone may have ocean-covered surfaces, stable CO{sub 2}/H{sub 2}O-rich atmospheres, and high mean surface temperatures.

  9. Exchange of condensed matter among the outer and terrestrial protoplanets and the effect on surface impact and atmospheric accretion

    SciTech Connect

    Ip, W.H.; Fernandez, J.A.

    1988-04-01

    The potential contribution of volatile material to planetary atmospheres from comet impact is presently estimated on the basis of a scenario of extensive gravitational scattering of icy planetesimals from the other planets and cometary nuclei in the early and late phase of the bombardment process. In the earth's case, the cometary water is sufficient to compete with the water contained in the nonvolatile planetesimals condensed in the region of the terrestrial planets; the same consideration could be applied to Mars and Venus, although it is not yet clear how the cometary chemical compositions may have affected the evolution of early planetary atmospheres. 52 references.

  10. North America's net terrestrial carbon exchange with the atmosphere 1990-2009

    SciTech Connect

    King, Anthony W.; Andres, Robert; Davis, Kenneth J.; Hafer, M.; Hayes, Daniel J.; Huntzinger, Deborah N.; de Jong, Bernardus; Kurz, Werner; McGuire, A. David; Vargas, Rodrigo; Wei, Yaxing; West, Tristram O.; Woodall, Chris 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 over the period (1990-2009). 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 America 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 atmospheric inversion estimate forms the lower bound of that range (a larger land-sink) and the inventory-based estimate the upper (a smaller land sink). Integrating across estimates, a “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. The continent’s CO2 source to sink ratio for this time period was likely in the range of 4:1 to 3:1.

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

    SciTech Connect

    King, Anthony Wayne [ORNL; Andres, Robert Joseph [ORNL; Davis, Ken J. [Pennsylvania State University; Hafer, Mark [Canadian Forest Service; Hayes, Daniel J [ORNL; Huntzinger, Deborah N [Northern Arizona University; De Jong, Ben [Unidad Villahermosa, Mexico; Kurz, Werner [Canadian Forest Service; McGuire, Anthony [University of Alaska, Fairbanks; Vargas, Roberto [University of Delaware; Wei, Yaxing [ORNL; West, Tristam O. [Joint Global Change Research Institute, PNNL; Woodall, Christopher [United States Department of Agriculture (USDA), United States Forest Service (USFS), Northern Resear

    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 over the period (1990-2009). 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 America 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 atmospheric inversion estimate forms the lower bound of that range (a larger land-sink) and the inventory-based estimate the upper (a smaller land sink). Integrating across estimates, a 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. The continent s CO2 source to sink ratio for this time period was likely in the range of 4:1 to 3:1.

  12. Atmospheres on the terrestrial planets: Clues to origin and evolution

    NASA Astrophysics Data System (ADS)

    Pepin, Robert O.

    2006-11-01

    Earth, Venus and Mars reached their final sizes in the first 100 Myr or so of solar system history. For part of that time the growing planets and the materials forming them were immersed in the Sun-like gases of the solar nebula, and so one would expect that their early volatile inventories were acquired from the nebula. But the compositions of atmospheres presently on these planets are not solar, and therein lies a complex and fascinating story of physical and chemical evolution over the past 4.5 Ga. Records of physical processing survive most clearly in the chemically inert noble gases, and data on the elemental and isotopic abundances of these trace constituents, now from Mars and Venus as well as Earth, point to atmospheric histories punctuated by enormous inputs of energy from early astrophysical sources long since vanished. Observational and theoretical advances during the past 30 years underpin current evolutionary models in which primordial solar-like atmospheric gases are fractionated by gravitational escape, driven on Earth by a giant Moon-forming impact, on Mars by sputtering at high altitudes, and on all three planets by adsorption of intense ultraviolet radiation from the young Sun. Residual atmospheres left behind after these outflows to space are augmented by planetary degassing, including species generated in their interiors by radioactive decay. Interplay over time of these mechanisms for loss and gain of atmospheric gases can account for many of the details of contemporary noble gas distributions. These of course are just models. However they have predictive power for compositions as yet unmeasured, particularly on Venus, and the modeling assumptions are in principle testable by experiment or theory. The fundamental question of whether nature actually shaped the atmospheres in this way is still unanswered, but at least we have an outline of how it might have happened.

  13. Photochemistry in Terrestrial Exoplanet Atmospheres I: Photochemistry Model and Benchmark Cases

    E-print Network

    Hu, Renyu; Bains, William

    2012-01-01

    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 red...

  14. Processes Impacting Atmosphere-Surface Exchanges at Arctic Terrestrial Sites

    NASA Astrophysics Data System (ADS)

    Persson, Ola; Grachev, Andrey; Konopleva, Elena; Cox, Chris; Stone, Robert; Crepinsek, Sara; Shupe, Matthew; Uttal, Taneil

    2015-04-01

    Surface energy fluxes are key to the annual cycle of near-surface and soil temperature and biologic activity in the Arctic. While these energy fluxes are undoubtedly changing to produce the changes observed in the Arctic ecosystem over the last few decades, measurements have generally not been available to quantify what processes are regulating these fluxes and what is determining the characteristics of these annual cycles. The U.S. National Oceanic and Atmospheric Administration has established, or contributed to the establishment of, several terrestrial "supersites" around the perimeter of the Arctic Ocean at which detailed measurements of atmospheric structure, surface fluxes, and soil thermal properties are being made. These sites include Barrow, Alaska; Eureka and Alert, Canada; and Tiksi, Russia. Atmospheric structure measurements vary, but include radiosoundings at all sites and remote sensing of clouds at two sites. Additionally, fluxes of sensible heat and momentum are made at all of the sites, while fluxes of moisture and CO2 are made at two of the sites. Soil temperatures are also measured in the upper 120 cm at all sites, which is deep enough to define the soil active layer. The sites have been operating between 3 years (Tiksi) and 24 years (Barrow). While all sites are located north of 71° N, the summer vegetation range from lush tundra grasses to rocky soils with little vegetation. This presentation will illustrate some of the atmospheric processes that are key for determining the annual energy and temperature cycles at these sites, and some of the key characteristics that lead to differences in, for instance, the length of the summer soil active layer between the sites. Atmospheric features and processes such as cloud characteristics, snowfall, downslope wind events, and sea-breezes have impacts on the annual energy cycle. The presence of a "zero curtain" period, when autumn surface temperature remains approximately constant at the freezing point for up to a month, seems to be a characteristic of the autumn freeze-up in the annual energy cycle at some of the sites.

  15. 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.

  16. Atmospheric Dynamics of Terrestrial Exoplanets over a Wide Range of Orbital and Atmospheric Parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Showman, Adam P.

    2015-05-01

    The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest 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, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius 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 streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate.

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

    E-print Network

    Hu, Renyu

    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 ...

  18. 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 ...

  19. Photochemistry in Terrestrial Exoplanet Atmospheres. I. Photochemistry Model and Benchmark Cases

    NASA Astrophysics Data System (ADS)

    Hu, Renyu; Seager, Sara; Bains, William

    2012-12-01

    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., CH4 and CO2) 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 CO2-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.

  20. 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.

  1. The Atmospheric Supply of Terrestrial Authigenic Phosphate Minerals to Open Marine Sediments

    NASA Astrophysics Data System (ADS)

    Flaum, J. A.; Jacobson, A. D.; Sageman, B. B.

    2007-12-01

    Authigenic P-bearing minerals (Pauth), such as carbonate fluorapatite, form within shallow marine sediments as biological processes degrade organic matter and release associated phosphate to the dissolved pool during early diagenesis. Thus, Pauth is commonly used as a proxy for productivity in modern and ancient marine depositional environments. To help refine this proxy and further improve understanding of the marine P cycle, we investigated if dust deposition could supply terrestrially derived Pauth and other P-bearing phases to modern marine sediments. We used the SEDEX sequential extraction procedure to quantify the occurrence of P in ten samples of loess from the Chinese Loess Plateau, a major source of dust to the North Pacific Ocean (NPO). On average, 40% of the total P within Chinese Loess occurs as Pauth, 33% as detrital apatite (Pdet), 17% in organic matter (Porg), and 10% bound to Fe-Al oxides (Pox). Using eolian dust and total P accumulation rates reported for core LL44-GC3 taken from the central NPO, we find that ~86% of the total P accumulation within the central NPO could originate from the atmospheric deposition of Pauth and Pdet. Hence, productivity estimates based upon total P accumulation for this site are likely lower than previously estimated. Our findings suggest that marine productivity studies predicated on the measurement of Pauth need to quantify the fraction of Pauth supplied from terrestrial sources. This may be even more significant along continental margins where rivers can supply sediments with high concentrations of Pauth minerals.

  2. Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 539557 Ionogram heighttimeintensity observations of descending

    E-print Network

    Christakis, Nikolaos

    2006-01-01

    layers; Atmospheric tides ARTICLE IN PRESS www.elsevier.com/locate/jastp 1364-6826/$ - see front matter r;1. Introduction The mid-latitude sporadic E layers (Es), which are thin layers of metallic ion plasma that formJournal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 539­557 Ionogram height

  3. Enhanced transfer of terrestrially derived carbon to the atmosphere in a flooding event

    E-print Network

    Grossman, Ethan L.

    we demonstrate that the summer 2011 flood in the Mississippi River basin, caused by extreme to the atmosphere in June and August 2011. This work shows that enhanced flooding, which may or may not be causedEnhanced transfer of terrestrially derived carbon to the atmosphere in a flooding event Thomas S

  4. 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.

  5. Application of MODTRAN ™ to ExtraTerrestrial Planetary Atmospheres

    Microsoft Academic Search

    Lawrence S. Bernstein; Alexander Berk; Robert L. Sundberg

    MODTRAN ™ (1) is a widely used radiative-transfer (RT) code for computing the transmission and emission of the Earth's atmosphere. However, the RT algorithms used in MODTRAN ™ are generally applicable to any layered atmosphere, and, in principle, can be applied to any planetary atmosphere. The primary modification required for this application is the development of the appropriate spectral properties

  6. Planetary Atmospheres Earth and the Other Terrestrial Worlds

    E-print Network

    Crenshaw, Michael

    of molecular nitrogen (N2 - 78%) and oxygen (O2 - 21%) Atmospheric Pressure Gas pressure depends on both increases the pressure. #12;2 Atmospheric Pressure · Pressure and density decrease with altitude because of Atmospheres · Create pressure that determines whether liquid water can exist on surface · Absorb and scatter

  7. Exploring the Sensitivity of Terrestrial Ecosystems and Atmospheric Exchange

    E-print Network

    Jain, Atul K.

    with ISAM. #12;Global Terrestrial C-N ISAM · 18 Biome types · 0.5 x 0.5 degree resolution · Carbon cycle · Nitrogen cycle · Feedbacks: Climate-C-N-LUC... Biome Types Yang et al. (2009, GBC) Temperate Deciduous Temperate Evergreen Tropical Evergreen Tropical Deciduous Boreal Forest Savanna Grassland Shrubland Tundra

  8. Ecological impacts of atmospheric CO2 enrichment on terrestrial ecosystems

    Microsoft Academic Search

    Christian Körner

    2003-01-01

    Global change has many facets, of which land use and the change of atmospheric chemistry are unquestioned primary agents, which induce a suite of secondary effects, including climatic changes. The largest single contribution to the compositional change of the atmosphere, CO2 enrichment, has (besides its influence on climate) immediate and direct effects on plants. Quantitatively, CO2 is the plant 'food'

  9. Mineral Reaction Buffering of Venus' Atmosphere: Constraints for Terrestrial Exoplanets

    NASA Astrophysics Data System (ADS)

    Treiman, A. H.; Bullock, M. A.

    2011-12-01

    For many years, it has been suggested that the composition of Venus' atmosphere, notably its abundance of CO2, is controlled by gas-solid reactions at its surface. However, the suggested reaction for Venus atmosphere, CaCO3 + SiO2 = CaSiO3 + CO2, cannot act as a buffer - the pressure-temperature trajectory of the reaction and that of the atmosphere (a dry adiabat) do not provide buffering capacity. Instead, perturbations to T or P(CO2) would produce catastrophic expansion or collapse of the atmosphere. This instability can be generalized to all devolatilization reactions that produce a radiatively active gas in a planetary atmosphere dominated by such gases, and gives a simple thermochemical criterion for whether a reaction could buffer such an atmosphere. Simple decarbonation reactions fail this criterion, implying that the abundance of CO2 in a CO2-dominated atmosphere cannot be buffered by chemical reactions with the surface. The same inference holds for the abundance of H2O in an H2O-dominated (steam) atmosphere (e.g., exoplanet GJ 1214b), and for the abundance of methane above a methane-hydrate ice surface (e.g., a Titan-like exoplanet). Buffering of minor gases is more likely; the proposed mineral buffer reaction for SO2 in the Venus atmosphere (FeS2 + CO2 = Fe3O4 + SO2 + CO) passes the thermochemical criterion, as does a reaction involving Ca sulfate (CaSO4 + CO = CaCO3 + SO2). These inferences can be generalized to extrasolar Venus-like planets - those with surfaces hot enough to permit rapid chemical reactions between solids and gas, yet cool enough that their atmospheres contain (are dominated by) gases active in thermal radiative equilibria. On the other hand, it seems likely that abundances of minor atmospheric gas species can be buffered by crust-atmosphere chemical reactions. So, minor species in exoplanet atmospheres may be particularly important for constraining the chemical characteristics of their surfaces.

  10. 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 ...

  11. 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

  12. 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

  13. 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

  14. Production of OH Molecules by Hot Oxygen Atoms in the Upper Atmospheres of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Gacesa, M.; Kharchenko, V.

    2012-12-01

    Photodissociation of CO2 and O2 molecules and dissociative recombination of oxygen molecular ions are among the most important sources of suprathermal oxygen atoms in the upper atmospheres of terrestrial planets. The produced hot oxygen atoms can transfer energy in collisions with thermal atmospheric gases and perturb local equilibrium conditions or induce non-thermal chemical reactions. One such process is the reaction of hot O atoms with hydrogen molecules, leading to production of highly rotationally-vibrationally excited OH molecules. We report the results of extensive reactive quantum scattering calculations of O + H2(v, j) ? H + OH(v', j') and corresponding non-thermal rate coefficients at the atmospheric conditions found on Earth and Mars for different solar conditions. Possible implications of this comparative study on the physics of upper atmospheres of terrestrial planets are discussed.

  15. Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002) 19731978 www.elsevier.com/locate/jastp

    E-print Network

    Steinhoff, Heinz-Jürgen

    2002-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002) 1973­1978 www / Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002) 1973­1978 Fig. 1. Left: Undisturbed of Physics, University of Osnabruck, Barbarastr. 7, Osnabruck 49080, Germany Received 2 March 2001; received

  16. Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002) 481488 www.elsevier.com/locate/jastp

    E-print Network

    Anastasiadis, Anastasios

    2002-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002) 481­488 www of Atmospheric and Solar-Terrestrial Physics 64 (2002) 481­488 Fig. 1. The distributions of the source longitude.elsevier.com/locate/jastp Acceleration of solar energetic particles: the case of solar ares Anastasios Anastasiadis Institute for Space

  17. 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

  18. In situ observations of the atmospheres of terrestrial planetary bodies

    NASA Astrophysics Data System (ADS)

    Harri, Ari-Matti

    2005-11-01

    Direct observations of planetary atmospheres are scarce and significantly more data are needed for the understanding of their behavior. The principal theme of this dissertation is the exploration of planetary atmospheres by means of in situ observations, focusing on investigations performed by payloads operating on the planetary surface. The contextual frame includes the whole palette of planetary exploration including definition of scientific objectives, observational strategies, scientific payload and data analysis, as well as development of technological solutions and simulation models for planetary missions. Thus approach also led to the initiation of the planetary missions MetNet and NetLander to Mars. This work contributes to both in situ atmospheric observations and atmospheric modeling, which are strongly intertwined. Modeling efforts require observations to give solid background and foundation for the simulations, and on the other hand, definition of observational strategies and instrumentation gets guidance from modeling efforts to optimize the use of mission resources, as is successfully demonstrated in this dissertation. The dissertation consists of Summary and nine original scientific publications. Publications 1 to 7 and Summary address the development of new atmospheric science payloads for exploration missions to Mars and Titan, a Saturnian moon. Actual and planned missions included are the Mars-96 Program and its Small Surface Stations and Penetrators during the years 1988-1996, PPI/HASI onboard the Cassini/Huygens spacecraft to Saturn and its moon Titan in 1989-2005, the MET-P payload onboard the Mars Polar Lander in 1997-1999, the BAROBIT instrument for the Beagle 2 lander in 2001-2003, the NetLander Mars Mission in 1997-2001 and the ongoing Mars MetNet Mission, started in 2000. Specifically, Publication 4 reviews the sensor qualification process that facilitated the use of new type of atmospheric sensors at Mars, while Publications 2 and 7, as well as Summary, address the highly successful determination of the Titan atmospheric pressure profile. Publication 8 combines in situ observations and simulations by analyzing Mars Pathfinder measurements with the help of a Martian mesoscale atmospheric model. Finally, in Publication 9 the effect of airborne dust and CO 2 on the radiative transfer in the Martian atmosphere is assessed and a new radiative transfer paramerization scheme for the mesoscale model is introduced.

  19. 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.

  20. 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.

  1. Late Impacts and the Origins of the Atmospheres on the Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Stewart, S. T.; Lock, S. J.; Parai, R.; Tucker, J. M.

    2014-12-01

    Models for the origin of terrestrial atmospheres typically require an intricate sequence of events, including hydrodynamic escape, outgassing of mantle volatiles and late delivery. Here we discuss the origin of the atmospheres on the terrestrial planets in light of new ideas about the formation of the Moon, giant impact induced atmospheric loss and recent noble gas measurements. Our new measurements indicate that noble gases in the Earth's atmosphere cannot be derived from any combination of fractionation of a nebular-derived atmosphere followed by outgassing of deep or shallow mantle volatiles. While Ne in the mantle retains a nebular component, the present-day atmosphere has no memory of nebular gases. Rather, atmospheric noble gases have a close affinity to chondrites. On the other hand, Venus's atmosphere has 20 and 70 times higher abundance of 20Ne and 36Ar, respectively, and a 20Ne/22Ne ratio closer to the solar value than Earth's atmosphere. While the present atmosphere of Mars is significantly fractionated in the lighter noble gases due to long term atmospheric escape, the Kr isotopic ratios in Martian atmosphere are identical to solar. Thus, while Earth's atmosphere has no memory of accretion of nebular gases, atmospheres on both Venus and Mars preserve at least a component of nebular gases. To explain the above observations, we propose that a common set of processes operated on the terrestrial planets, and that their subsequent evolutionary divergence is simply explained by planetary size and the stochastic nature of giant impacts. We present geochemical observations and simulations of giant impacts to show that most of Earth's mantle was degassed and the outgassed volatiles were largely lost during the final sequence of giant impacts onto Earth. Earth's noble gases were therefore dominantly derived from late-accreting planetesimals. In contrast, Venus did not suffer substantial atmospheric loss by a late giant impact and retains a higher abundance of both nebular and chondritic noble gases compared to Earth. Fast-accreting Mars has a noble gas signature inherited from the solar nebula, and its low mass allowed for gravitational escape of the volatile components in late accreting planetesimals due to vaporization upon impact.

  2. 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

  3. 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.

  4. Habitability of Terrestrial Planets in the Early Solar System

    Microsoft Academic Search

    N. H. SLEEP

    2001-01-01

    The Protoearth, Mars, Venus, and the Moon-forming impactor were potentially habitable in the early solar system. The interiors of larger asteroids had habitable circulating water. To see when the inner solar system became continuously habitable, one needs to consider the most dangerous events and the safest refugia from them. Early geochemical and accretionary processes set the subsequent silicate planet reservoirs

  5. 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.

  6. Exploring the control of land-atmospheric oscillations over terrestrial vegetation productivity

    NASA Astrophysics Data System (ADS)

    Depoorter, Mathieu; Green, Julia; Gentine, Pierre; Liu, Yi; van Eck, Christel; Regnier, Pierre; Dorigo, Wouter; Verhoest, Niko; Miralles, Diego

    2015-04-01

    Vegetation dynamics play an important role in the climate system due to their control on the carbon, energy and water cycles. The spatiotemporal variability of vegetation is regulated by internal climate variability as well as natural and anthropogenic forcing mechanisms, including fires, land use, volcano eruptions or greenhouse gas emissions. Ocean-atmospheric oscillations, affect the fluxes of heat and water over continents, leading to anomalies in radiation, precipitation or temperature at widely separated locations (i.e. teleconnections); an effect of ocean-atmospheric oscillations on terrestrial primary productivity can therefore be expected. While different studies have shown the general importance of internal climate variability for global vegetation dynamics, the control by particular teleconnections over the regional growth and decay of vegetation is still poorly understood. At continental to global scales, satellite remote sensing offers a feasible approach to enhance our understanding of the main drivers of vegetation variability. Traditional studies of the multi-decadal variability of global vegetation have been usually based on the normalized difference vegetation index (NDVI) derived from the Advanced Very High Resolution Radiometer (AVHRR), which extends back to the early '80s. There are, however, some limitations to NDVI observations; arguably the most important of these limitations is that from the plant physiology perspective the index does not have a well-defined meaning, appearing poorly correlated to vegetation productivity. On the other hand, recently developed records from other remotely-sensed properties of vegetation, like fluorescence or microwave vegetation optical depth, have proven a significantly better correspondence to above-ground biomass. To enhance our understanding of the controls of ocean-atmosphere oscillations over vegetation, we propose to explore the link between climate oscillation extremes and net primary productivity over the last two decades. The co-variability of a range of climate oscillation indices and newly-derived records of fluorescence and vegetation optical depth is analyzed using a statistical framework based on correlations, bootstrapping and Empirical Orthogonal Functions (EOFs). Results will enable us to characterize regional hotspots where particular climatic oscillations control vegetation productivity, as well as allowing us to underpin the climatic variables behind this control.

  7. Synchronized terrestrial-atmospheric deglacial records around the North Atlantic

    SciTech Connect

    Bjoerck, S.; Rasmussen, T.L. [Univ. of Copenhagen (Denmark); Kromer, B. [Heidelberg Academy of Sciences (Germany)] [and others

    1996-11-15

    On the basis of synchronization of three carbon-14 ({sup 14}C)-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 {plus_minus} 80 years before the present. A 150-year-long cooling in the early Preboreal, associated with rising {Delta} {sup 14}C values, is evident in all records and indicates an ocean ventilation change. This cooling is similar to earlier deglacial coolings, and box-model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the North Atlantic heat conveyor, although the Younger Dryas may have been begun as an anomalous meltwater event. 53 refs., 8 figs., 1 tab.

  8. Preliminary experiment requirements document for Solar and Terrestrial Atmospheres Spectrometer (STAS)

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The principal scientific objective of the Solar and Terrestrial Atmospheres Spectrometer (STAS) project is the measurement of the absolute ultraviolet solar spectral irradiance with: (1) resolution of better than 15 mA, and (2) absolute irradiance uncertainty at the state of the art (less than or equal to 3%). High measurement accuracy coupled with high spectral resolution are necessary to identify the nature of the radiation, its variability, and to identify solar processes which may cause the changes. Solar radiation between 1200 and 3600 A dominates the photochemistry of the mesosphere and stratosphere. Some important minor species, such as NO, show very complex and fundamentally narrow structure in their photodestruction cross sections, especially in the region of the Schumann-Runge bands of O2. Understanding the photochemical processes in the terrestrial atmosphere requires knowledge of both the cross sections and of the solar spectrum with the highest possible resolution and accuracy.

  9. Atmospheric circulation modeling of super Earths and terrestrial extrasolar planets using the SPARC/MITgcm

    NASA Astrophysics Data System (ADS)

    Kataria, T.; Showman, A. P.; Haberle, R. M.; Marley, M. S.; Fortney, J. J.; Freedman, R. S.

    2013-12-01

    The field of exoplanets continues to be a booming field of research in astronomy and planetary science, with numerous ground-based (e.g., SuperWASP, HARPS-N and S) and space-based surveys (e.g., Kepler) that detect and characterize planets ranging from hot Jupiters, Jovian-sized planets orbiting less than 0.1 AU from their star, to super Earths and terrestrial exoplanets, planets that have masses equal to or less than 10 times that of Earth with a range of orbital distances. Atmospheric circulation modeling plays an important role in the characterization of these planets, helping to constrain observations that probe their atmospheres. These models have proven successful in understanding observations of transiting exoplanets (when the planet passes in front of the star along our line of sight) particularly when the planet is passing through secondary eclipse (when the planet's dayside is visible). In modeling super Earths and terrestrial exoplanets, we must consider not only planets with thick fluid envelopes, but also traditional terrestrial planets with solid surfaces and thinner atmospheres. To that end, we present results from studies investigating the atmospheric circulation of these classes of planets using the SPARC/MITgcm, a state-of-the-art model which couples the MIT General Circulation Model with a plane-parallel, two-stream, non-gray radiative transfer model. We will present results from two studies, the first focusing on the circulation of GJ 1214b, a super-Earth detected by the MEarth ground-based survey, and a second study which explores the circulation of terrestrial exoplanets orbiting M-dwarfs.

  10. Greening the terrestrial biosphere: simulated feedbacks on atmospheric heat and energy circulation

    Microsoft Academic Search

    S. A. Cowling; C. D. Jones; P. M. Cox

    2009-01-01

    Much research focuses on how the terrestrial biosphere influences climate through changes in surface albedo (reflectivity),\\u000a stomatal conductance and leaf area index (LAI). By using a fully-coupled GCM (HadCM3LC), our research objective was to induce\\u000a an increase in the growth of global vegetation to isolate the effect of increased LAI on atmospheric exchange of heat and\\u000a moisture. Our Control simulation

  11. Terrestrial biomarkers : a proxy for reconstructing the past history of atmospheric circulation and vegetation changes

    NASA Astrophysics Data System (ADS)

    Sicre, M.; Ezat, U.

    2006-12-01

    The Sea Air Exchange Program (SEAREX) has significantly contributed to the understanding of the long-range transport of aerosols, over distances of several thousand kilometers. Naturally occurring organic compounds (n-alkanes, fatty alcohols, long-chain n-aldehydes,...) of epicuticular waxes produced by terrestrial plant provide important background information on the source emission and atmospheric transport pathways of terrestrial carbon. Source identifications based on airborne biomarker distribution patterns during SEAREX experiment have shown to be consistent with the origin of the aerosols infered by isentropic air mass trajectories. More recent progress have been made from aerosol monitoring over several years, showing that leaf waxes are introduced into the atmosphere mainly by wind ablation off the living vegetation rather than from soil remobilization of detrital waxes during soil deflation. The ablated wax constituents would thus integrate the vegetation signature over large continental areas and might be applied to investigate vegetation changes at a regional scale. Few studies have shown that stratigraphic records of terrestrial biomarkers in hemi-pelagic and pelagic sediments remote from the continents, where pollen are lacking, can be useful tools to reconstruct the atmospheric circulation history and/or changes of the vegetation production.

  12. 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.

  13. 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 ...

  14. Historical space psychology: Early terrestrial explorations as Mars analogues

    NASA Astrophysics Data System (ADS)

    Suedfeld, Peter

    2010-03-01

    The simulation and analogue environments used by psychologists to circumvent the difficulties of conducting research in space lack many of the unique characteristics of future explorations, especially the mission to Mars. This paper suggests that appropriate additional analogues would be the multi-year maritime and terrestrial explorations that mapped the surface of the Earth in previous centuries. These, like Mars, often involved a hazardous trek through unknown territory, flanked by extended, dangerous voyages to and from the exploration sites. Characteristic issues included interpersonal relationships under prolonged stress, stretches of boredom interspersed with intense work demands, the impossibility of rescue, resupply, or other help from home, chronic danger, physical discomfort and lack of privacy, and the crucial role of the leader. Illustrative examples of one important factor, leadership style, are discussed. The examination of such expeditions can help to identify the psychological stressors that are likely to be experienced by Mars explorers, and can also indicate countermeasures to reduce the damaging impact of those stressors.

  15. 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.

  16. Nested atmospheric inversion for the terrestrial carbon sources and sinks in China

    NASA Astrophysics Data System (ADS)

    Jiang, F.; Wang, H. W.; Chen, J. M.; Zhou, L. X.; Ju, W. M.; Ding, A. J.; Liu, L. X.; Peters, W.

    2013-08-01

    In this study, we establish a nested atmospheric inversion system with a focus on China using the Bayesian method. The global surface is separated into 43 regions based on the 22 TransCom large regions, with 13 small regions in China. Monthly CO2 concentrations from 130 GlobalView sites and 3 additional China sites are used in this system. The core component of this system is an atmospheric transport matrix, which is created using the TM5 model with a horizontal resolution of 3° × 2°. The net carbon fluxes over the 43 global land and ocean regions are inverted for the period from 2002 to 2008. The inverted global terrestrial carbon sinks mainly occur in boreal Asia, South and Southeast Asia, eastern America and southern South America. Most China areas appear to be carbon sinks, with strongest carbon sinks located in Northeast China. From 2002 to 2008, the global terrestrial carbon sink has an increasing trend, with the lowest carbon sink in 2002. The inter-annual variation (IAV) of the land sinks shows remarkable correlation with the El Niño Southern Oscillation (ENSO). The terrestrial carbon sinks in China also show an increasing trend. However, the IAV in China is not the same as that of the globe. There is relatively stronger land sink in 2002, lowest sink in 2006, and strongest sink in 2007 in China. This IAV could be reasonably explained with the IAVs of temperature and precipitation in China. The mean global and China terrestrial carbon sinks over the period 2002-2008 are -3.20 ± 0.63 and -0.28 ± 0.18 PgC yr-1, respectively. Considering the carbon emissions in the form of reactive biogenic volatile organic compounds (BVOCs) and from the import of wood and food, we further estimate that China's land sink is about -0.31 PgC yr-1.

  17. Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 901916 www.elsevier.com/locate/jastp

    E-print Network

    Chan, Kwing Lam

    2003-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 901­916 www.elsevier.com/locate/jastp Modeling studies with QBO: II. Solar cycle e ect H.G. Mayra;, J.G. Mengelb, D.P. Drobc, K.L. Chand, H May 2003 Abstract Solar cycle activity e ects (SCAE) in the lower and middle atmosphere, reported

  18. 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.

  19. 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.

  20. Stability of CO2 Atmospheres on Terrestrial Exoplanets in the Proximity of M Dwarfs

    NASA Astrophysics Data System (ADS)

    Gao, P.; Hu, R.; Yung, Y. L.

    2013-12-01

    M dwarfs are promising targets for the search and characterization of terrestrial exoplanets that might be habitable, as the habitable planets around M dwarfs are in much more close-in orbits compared to their counterparts around Sun-like stars. CO2, one of the most important greenhouse gases on our planet, is conventionally adopted as a major greenhouse gas in studying the habitability of terrestrial exoplanets around M dwarfs. However, the stability of CO2 in terrestrial atmospheres has been called into question due to the high FUV/NUV flux ratio of some M dwarfs in comparison to that of Sun-like stars. While CO2 is photolyzed into CO and O by photons in the FUV, with O2 forming from the O atoms through third body catalytic reactions, NUV photons are able to photolyze water, producing HOx radicals which go on to catalytically recombine the relatively stable CO and O2 molecules back into CO2. The comparatively low NUV flux of some M dwarfs leads to a significantly reduced efficiency of catalytic recombination of CO and O2 and the possible net destruction of CO2 and the build up of CO and O2. In this work we test the above hypothesis using a 1D photochemical kinetics model for a Mars-sized planet with an initial atmospheric composition similar to that of Mars and the incoming stellar flux of a weakly active M dwarf, assuming the exoplanet is 0.1 AU away from its parent star, in proximity of its habitable zone. We show that a CO2-dominated atmosphere can be converted into a CO2/CO/O2-dominated atmosphere in 10^3-10^4 years by CO2 photolysis. This process is kept from running away by a combination of O2 photolysis, three body reactions of O, O2, and another species to form O3, and reactions of CO with OH to form CO2 and H. However, such a large amount of O2 and CO, combined with some amount of H and H2, may be susceptible to spontaneous combustion or detonation, and thus could prove to be an especially unstable state in itself. Thus there could arise a situation whereby a CO2 atmosphere dissociating into CO and O2 would be periodically and violently converted back into mostly CO2 due to some "spark". Our simulation results suggest that it is unlikely that CO2 atmospheres can remain stable on terrestrial planets around M dwarfs with high FUV/NUV flux ratios unless it is extremely quiescent. Furthermore, any detection of O2 and O3 in such atmospheres is far more likely to be due to photochemical processes rather than as a result of biology.

  1. The photochemistry of the early atmosphere

    NASA Technical Reports Server (NTRS)

    Levine, J. S.

    1985-01-01

    The composition of the earth's present atmosphere is described. The formation of the earth from the coalescence and accretion of the refractory elements of the solar nebula is examined. Two possible compositions of the prebiological paleoatmosphere, which are a reducing atmosphere of CH4, NH3, and H2 or a mildly reducing atmosphere of H2O, CO2, and N2, and their photochemistry are analyzed. General photochemical and chemical processes are reviewed. The use of the coupled continuity-transport equation to calculate the vertical distribution of each species is discussed. A study of the photochemical process of CH4 and NH3 reveals that the reducing atmosphere could not possibly exist. An analysis of the photochemistry and chemistry of the H2O, CO2, and N2 atmosphere reveals that the photodissociation of H2O and CO2 results in a prebiotic source of O2, H2CO, and HCN, which are the components for the evolution of photosynthetic organisms and a strongly oxidizing atmosphere. The reactions which produce O2 and H2CO from H2O and CO2, and the relation between H2O and CO2 concentrations and O2 levels are investigated. The formation of O3 photochemically from O2 is explained.

  2. Evidence for and implications of an Early Archean terrestrial impact record

    NASA Technical Reports Server (NTRS)

    Lowe, Donald R.; Byerly, Gary R.

    1988-01-01

    Early Archean, 3.5 to 3.2 Ga, greenstone sequences in South Africa and Western Australia contain a well-preserved record of early terrestrial meteorite impacts. The main impact-produced deposits are layers, 10 cm to over 1 m thick, composed largely of sand-sized spherules, 0.1 to 4 mm in diameter. The beds studied to date show an assemblage of features indicating formation by the fall of debris from impact-generated ejecta clouds. Some presented data effectively rule out normal magmatic or sedimentary processes in the origin of these units and provide substantial support for an origin by large impacts on the early earth. The presence of at least four, remarkably thick, nearly pure spherule layers suggests that smaller-scale impact deposits may be even more abundant in these sequences. The existence of a well-preserved Archean terrestrial impact record suggests that a direct source of evidence is available regarding a number of important aspects of early earth history.

  3. Water Formation in the Upper Atmosphere of the Early Earth

    NASA Astrophysics Data System (ADS)

    Fleury, Benjamin; Carrasco, Nathalie; Marcq, Emmanuel; Vettier, Ludovic; Määttänen, Anni

    2015-07-01

    The water concentration and distribution in the early Earth's atmosphere are important parameters that contribute to the chemistry and the radiative budget of the atmosphere. If the atmosphere above the troposphere is generally considered as dry, photochemistry is known to be responsible for the production of numerous minor species. Here we used an experimental setup to study the production of water in conditions simulating the chemistry above the troposphere of the early Earth with an atmospheric composition based on three major molecules: N2, CO2, and H2. The formation of gaseous products was monitored using infrared spectroscopy. Water was found as the major product, with approximately 10% of the gas products detected. This important water formation is discussed in the context of the early Earth.

  4. Enhanced transfer of terrestrially derived carbon to the atmosphere in a flooding event

    NASA Astrophysics Data System (ADS)

    Bianchi, Thomas S.; Garcia-Tigreros, Fenix; Yvon-Lewis, Shari A.; Shields, Michael; Mills, Heath J.; Butman, David; Osburn, Christopher; Raymond, Peter; Shank, G. Christopher; Dimarco, Steven F.; Walker, Nan; Reese, Brandi Kiel; Mullins-Perry, Ruth; Quigg, Antonietta; Aiken, George R.; Grossman, Ethan L.

    2013-01-01

    Rising CO2 concentration in the atmosphere, global climate change, and the sustainability of the Earth's biosphere are great societal concerns for the 21st century. Global climate change has, in part, resulted in a higher frequency of flooding events, which allow for greater exchange between soil/plant litter and aquatic carbon pools. Here we demonstrate that the summer 2011 flood in the Mississippi River basin, caused by extreme precipitation events, resulted in a "flushing" of terrestrially derived dissolved organic carbon (TDOC) to the northern Gulf of Mexico. Data from the lower Atchafalaya and Mississippi rivers showed that the DOC flux to the northern Gulf of Mexico during this flood was significantly higher than in previous years. We also show that consumption of radiocarbon-modern TDOC by bacteria in floodwaters in the lower Atchafalaya River and along the adjacent shelf contributed to northern Gulf shelf waters changing from a net sink to a net source of CO2 to the atmosphere in June and August 2011. This work shows that enhanced flooding, which may or may not be caused by climate change, can result in rapid losses of stored carbon in soils to the atmosphere via processes in aquatic ecosystems.

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

    E-print Network

    Erkaev, N V; Odert, P; Kulikov, Yu N; Kislyakova, K G; Khodachenko, M L; Güdel, M; Hanslmeier, A; Biernat, H

    2012-01-01

    The recently discovered low-density "super-Earths" Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent most likely planets which 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 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 a Sun-like G-type host star. For studying the thermosphere structure and escape we apply a 1-D hydrodynamic upper atmosphere model which solves the equations of mass, momentum and energy conservation for a planet with the mass and size of the Earth and for a "super-Earth" with a size of 2 R_Earth and a mass of 10 M_Earth. We calculate heating rates by the stellar soft X-rays and EUV radiation and expansion of th...

  6. 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.

  7. 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.

  8. 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. J.; Fyfe, J. C.; Werner, A. T.

    2014-02-01

    The impacts of climate change and increasing atmospheric CO2 concentration on the terrestrial uptake of carbon dioxide since 1860 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 an enhanced carbon uptake of around 44 gC m-2 yr-1 (or equivalently 63 gC m-2 yr-1 over the province's forested area), during the 1980s and 1990s, and continuing into the 2000s. About three-quarters of the simulated sink enhancement in our study compared to pre-industrial conditions 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 effects of harvesting, insect disturbances and land-use change are not considered.

  9. Soil-zone adsorption of atmospheric CO2 as a terrestrial carbon sink

    NASA Astrophysics Data System (ADS)

    Davidson, Gregg R.; Phillips-Housley, Ashley; Stevens, Maria T.

    2013-04-01

    Identifying and quantifying sources and sinks of CO2 is integral to developing global carbon budgets and effectively modeling climate change. Adsorption of CO2 onto mineral and soil surfaces has generally been regarded as an insignificant sink, though few studies have investigated adsorption on natural materials at temperatures and CO2 concentrations relevant to atmospheric or soil zone conditions. In this study, annual adsorption at the scale of North America was modeled for the upper 3 m of the Earth's surface (the root zone) based on our own and published adsorption data, and results compared with reported estimates for the North American terrestrial carbon sink during 2000-2005. Our results suggest that adsorption can account for 1-3% of the average annual sink during these years. At smaller regional scales where more adsorptive deposits are present, such as volcanic ash or high-organic soils, the sink may be significantly larger.

  10. 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.

  11. Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 102113 Statistics of sporadic iron layers and relation to

    E-print Network

    Chu, Xinzhao

    2006-01-01

    , sporadic iron layers (FeS) were observed with an annual average occurrence probability of 14%. The peak iron layers (FeS), first reported by Granier et al., (1989), are less understood than NaS dueJournal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 102­113 Statistics of sporadic iron

  12. Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 20532060 On possible drivers of Sun-induced climate changes

    E-print Network

    Usoskin, Ilya G.

    2006-01-01

    Author's personal copy Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 2053 of two current hypotheses on the dependence of climate change on solar activity. One of them states that variations in the tropospheric temperature are caused directly by changes of the solar radiance (total

  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. 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

  15. History of GPS Sounding : Special issue of Terrestrial, Atmospheric and Oceanic Science, 11(1), 1-20, March 2000

    E-print Network

    History of GPS Sounding : Special issue of Terrestrial, Atmospheric and Oceanic Science, 11(1), 1-20, March 2000 Yunck et al. 1 1/24/00 A History of GPS Sounding Thomas P. Yunck1 , Chao-Han Liu2 and Randolph Ware3 Abstract The roots of GPS sounding go back to the first days of interplanetary flight

  16. Comparative analysis of the atmospheres of early earth and early Mars

    NASA Astrophysics Data System (ADS)

    Durham, R.; Schmunk, R. B.; Chamberlain, J. W.

    Assuming that the primitive atmospheres of Mars and earth were similar and that present differences in atmospheres of earth and Mars are a result of their different distances from the sun and their different masses, the atmospheres of the early earth and early Mars were analyzed. A one-dimensional radiative-convective model derived from that of Kasting et al. (1984) and Kasting and Ackerman (1986) was then used to determine if a 1.3-bar CO2 partial pressure on Mars (which is equivalent to about 9 bars on earth) is consistent with the climatic conditions thought to have existed on earth four billion years ago. Results indicate that a dense CO2 atmosphere on early Mars at perihelion is consistent with conditions expected to have existed four billion years ago on earth. Earth would then have had a stable atmosphere with temperatures warm enough to support liquid water on the surface.

  17. 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

  18. Journal of the Atmospheric Sciences EARLY ONLINE RELEASE

    E-print Network

    Journal of the Atmospheric Sciences EARLY ONLINE RELEASE This is a preliminary PDF of the author that there will be visual differences and possibly some content differences between this version and the final published. Sensitivity experiments with the balanced vortex55 model show that, for a fixed amount of heating, SEF

  19. Meteorites and the Timing, Mechanisms, and Conditions of Terrestrial Planet Accretion and Early Differentiation

    NASA Astrophysics Data System (ADS)

    Halliday, A. N.; Kleine, T.

    Isotopic studies of meteorites provide the fundamental data for determining how the terrestrial planets, including Earth, accreted. Over the past few years there have been major advances in our understanding of both the timescales and processes of terrestrial planet accretion, largely as a result of better definition of initial solar system abundances of short-lived nuclides and their daughters, as determined from meteorites. Cosmogenic effects, cross calibrations with other isotopic systems, and decay constant uncertainties are also critical in many instances. Recent improvements to 182Hf-182W chronology in all these areas have been particularly noteworthy. Uncertainty has surrounded the initial Hf- and W-isotopic composition of the solar system and the meaning of the unradiogenic W-isotopic compositions of iron meteorite data, rendered complicated by cosmogenic effects. However, the timescales for the formation of certain iron meteorite parent bodies would appear to be very fast (<1 m.y.). Similarly, the accretion of Mars would appear to have been very fast, consistent with rapid accretion via runaway growth. Precise quantification is difficult, however, because martian meteorites display variable W-isotopic compositions that relate in part to the levels of depletion in siderophile elements. This is as expected from a planet that never achieved a well-mixed silicate reservoir characterized by uniform siderophile-element depletion, as is found on Earth. Therefore, attempts to apply W-isotopic models to martian meteorites need to be treated with caution because of this demonstrable variability in early source Hf/W presumably resulting from partial metal or core segregation. The current best estimates for martian reservoirs as represented by Zagami would imply formation within the first 1 m.y. of the solar system. The modeled timescales for metal segregation from the source of other meteorites, Nakhla, for example, would appear to be more like 10 m.y. These estimates are based on trace-element and isotopic data obtained from different and probably unrepresentative aliquots. Further high-quality combined trace-element and isotopic studies are needed to confirm this. Nevertheless, the chondritic 142Nd abundance for Zagami provides powerful supporting evidence that the W-isotopic effects record extremely rapid (<1 m.y.) accretion and core formation on Mars. The timescales for Earth accretion are significantly more protracted. The last major stage of accretion is thought to be the Moon-forming giant impact,the most recent Hf-W age estimates for which are in the range 40-50 m.y. after the start of the solar system. Applying this to accretion models for Earth provides evidence that some of the accreted metal did not fully equilibrate with silicate reservoirs. This cannot explain the very late apparent accretion ages deduced from other chronometers, in particular U-Pb. Either all the estimates for the Pb-isotopic composition of the bulk silicate Earth are in error or there was some additional late-stage U/Pb fractionation that removed Pb from the silicate Earth. If the latter was the case there was either late segregation of Pb to the core after W removal, or removal of Pb via atmospheric escape following the "giant impact." Changes in the mechanisms and partitioning associated with core formation are indeed predicted from the stability in the mantle of S-rich metal before, and sulfide after, the giant impact. However, losses from Earth also need to be evaluated. Strontium-isotopic data provide evidence of major late (>10 m.y.) losses of moderately volatile elements from the material that formed the Moon and probably Earth. The Earth's nonchondritic Mg/Fe may similarly reflect silicate losses during growth of Earth itself or the protoplanets that accreted to Earth. The budgets for plutonogenic Xe provide evidence that some erosion was extremely late (>100 m.y.), clearly postdating the giant impact and presumably related to irradiation and bombardment during the Hadean.

  20. 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.

  1. Testing a Simple Recipe for Estimating Thermal Hydrodynamic Escape Rates in Primitive Terrestrial Atmospheres

    NASA Astrophysics Data System (ADS)

    Friedson, A. J.; Yung, Y. L.; Chen, P.

    2014-12-01

    During the first billion years of the Sun's history, the emission of ultraviolet and X-ray radiation varied from ~100 to ~6 times greater than its present level. The absorption of this intense radiation in the upper atmospheres of the terrestrial planets is believed to have driven rapid hydrodynamic escape, either in the form of energy-limited escape or transonic blow-off. The calculation of escape rates under these circumstances, and in particular the nature of the correct condition to apply at the upper boundary, depends on whether or not the flow remains subsonic below the exobase. If the flow remains subsonic, the kinetic Jeans equations may be applied at the exobase; otherwise, the radius of the sonic point must be located and then appropriate boundary conditions applied at this radius. This seems to suggest that the full hydrodynamic escape problem needs to be solved iteratively to determine where the sonic radius falls and the type of boundary conditions that should be applied. Such an arduous undertaking is generally impractical for standard application in chemical evolution models or related studies. Fortunately, a much easier but still accurate approach to determining whether the flow remains subsonic below the exobase for a given amount of energy deposition has been provided by Johnson et al. (2013, Ap. J. Lett. 768:L4), who base their results on rigorous Discrete Simulation Monte Carlo models. Their model provides the ratio of the escape rate to the energy-limited value as a function of the total XUV heating. The XUV heating, however, is itself coupled to the escape rate through the radial structure of the upper atmosphere, which can become greatly distended for large heating rates. Here we present a simple recipe for estimating the hydrodynamic escape rate that includes the coupling between the escape rate, the radial structure, and the XUV heating while avoiding the use of demanding numerical calculations. The approach involves an iterative semi-analytical method for determining the effective radius of energy deposition, from which the escape rate, radial structure, and other parameters can be derived. We test its performance against some more elaborate, rigorous calculations of primitive-atmosphere hydrodynamic escape that are available in the literature.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. Contrasting roles of interception and transpiration in the hydrological cycle - Part 1: Simple Terrestrial Evaporation to Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Wang-Erlandsson, L.; van der Ent, R. J.; Gordon, L. J.; Savenije, H. H. G.

    2014-03-01

    Terrestrial evaporation consists of biophysical (i.e., transpiration) and physical fluxes (i.e., interception, soil moisture, and open water). The partitioning between them depends on both climate and the land surface, and determines the time scale of evaporation. However, few land-surface models have analysed and evaluated evaporative partitioning based on land use, and no studies have examined their subsequent paths in the atmosphere. This paper constitutes the first of two companion papers that investigate the contrasting effects of interception and transpiration in the hydrological cycle. Here, we present STEAM (Simple Terrestrial Evaporation to Atmosphere Model) used to produce partitioned evaporation and analyse the characteristics of different evaporation fluxes on land. STEAM represents 19 land-use types (including irrigated land) at sub-grid level with a limited set of parameters, and includes phenology and stress functions to respond to changes in climate conditions. Using ERA-Interim reanalysis forcing for the years 1999-2008, STEAM estimates a mean global terrestrial evaporation of 73 800 km3 year-1, with a transpiration ratio of 59%. We show that the terrestrial residence time scale of transpiration (days to months) has larger inter-seasonal variation and is substantially longer than that of interception (hours). Furthermore, results from an offline land-use change experiment illustrate that land-use change may lead to significant changes in evaporative partitioning even when total evaporation remains similar. In agreement with previous research, our simulations suggest that the vegetation's ability to transpire by retaining and accessing soil moisture at greater depth is critical for sustained evaporation during the dry season. Despite a relatively simple model structure, validation shows that STEAM produces realistic evaporative partitioning and hydrological fluxes that compare well with other global estimates over different locations, seasons and land-use types. We conclude that the simulated evaporation partitioning by STEAM is useful for understanding the links between land use and water resources, and can with benefit be employed for atmospheric moisture tracking.

  7. 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.

  8. Devonian rise in atmospheric oxygen correlated to the radiations of terrestrial plants and large predatory fish.

    PubMed

    Dahl, Tais W; Hammarlund, Emma U; Anbar, Ariel D; Bond, David P G; Gill, Benjamin C; Gordon, Gwyneth W; Knoll, Andrew H; Nielsen, Arne T; Schovsbo, Niels H; Canfield, Donald E

    2010-10-19

    The evolution of Earth's biota is intimately linked to the oxygenation of the oceans and atmosphere. We use the isotopic composition and concentration of molybdenum (Mo) in sedimentary rocks to explore this relationship. Our results indicate two episodes of global ocean oxygenation. The first coincides with the emergence of the Ediacaran fauna, including large, motile bilaterian animals, ca. 550-560 million year ago (Ma), reinforcing previous geochemical indications that Earth surface oxygenation facilitated this radiation. The second, perhaps larger, oxygenation took place around 400 Ma, well after the initial rise of animals and, therefore, suggesting that early metazoans evolved in a relatively low oxygen environment. This later oxygenation correlates with the diversification of vascular plants, which likely contributed to increased oxygenation through the enhanced burial of organic carbon in sediments. It also correlates with a pronounced radiation of large predatory fish, animals with high oxygen demand. We thereby couple the redox history of the atmosphere and oceans to major events in animal evolution. PMID:20884852

  9. Mentors, networks, and resources for early career female atmospheric scientists

    NASA Astrophysics Data System (ADS)

    Hallar, A. G.; Avallone, L. M.; Edwards, L. M.; Thiry, H.; Ascent

    2011-12-01

    Atmospheric Science Collaborations and Enriching NeTworks (ASCENT) is a workshop series designed to bring together early career female scientists in the field of atmospheric science and related disciplines. ASCENT is a multi-faceted approach to retaining these junior scientists through the challenges in their research and teaching career paths. During the workshop, senior women scientists discuss their career and life paths. They also lead seminars on tools, resources and methods that can help early career scientists to be successful. Networking is a significant aspect of ASCENT, and many opportunities for both formal and informal interactions among the participants (of both personal and professional nature) are blended in the schedule. The workshops are held in Steamboat Springs, Colorado, home of a high-altitude atmospheric science laboratory - Storm Peak Laboratory, which also allows for nearby casual outings and a pleasant environment for participants. Near the conclusion of each workshop, junior and senior scientists are matched in mentee-mentor ratios of two junior scientists per senior scientist. An external evaluation of the three workshop cohorts concludes that the workshops have been successful in establishing and expanding personal and research-related networks, and that seminars have been useful in creating confidence and sharing resources for such things as preparing promotion and tenure packages, interviewing and negotiating job offers, and writing successful grant proposals.

  10. 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.

  11. 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 ...

  12. Photochemistry in Terrestrial Exoplanet Atmospheres III: Photochemistry and Thermochemistry in Thick Atmospheres on Super Earths and Mini Neptunes

    E-print Network

    Hu, Renyu

    2014-01-01

    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 on super Earths and mini Neptunes, applicable for both H2-dominated atmospheres and non-H2-dominated atmospheres. Using this model to study thick atmospheres for wide ranges of temperatures and elemental abundances, we classify them into hydrogen-rich atmospheres, water-rich atmospheres, oxygen-rich atmospheres, and hydrocarbon-rich atmospheres. We find that carbon has to be in the form of CO2 rather than CH4 or CO in a H2-depleted water-dominated thick atmosphere, and that the preferred loss of light elements from an oxygen-poor carbon-rich atmosphere leads to formation of unsaturated hydrocarbons (C2H2 and C2H4). We apply our self-consistent atmosphere models to compute spectra and diagnostic features for known transiting low-mass exoplanets GJ 1214 b, HD 97658 b, and 55 Cnc e. For GJ 1...

  13. Terrestrial carbon sink observed from space: Sensitivity of atmospheric CO2 growth rates and seasonal cycle amplitudes to surface temperature

    NASA Astrophysics Data System (ADS)

    Schneising, Oliver; Reuter, Maximilian; Buchwitz, Michael; Heymann, Jens; Bovensmann, Heinrich; Burrows, John P.

    2014-05-01

    The terrestrial biosphere is currently acting as a net carbon sink on the global scale, exhibiting significant interannual variability in strength. To reliably predict the future strength of the land sink and its role in atmospheric CO2 growth, the underlying biogeochemical processes and their response to a changing climate need to be well understood. In particular, better knowledge of the impact of key climate variables such as temperature on the biospheric carbon reservoir is essential. Global satellite measurements of column-averaged mole fractions of atmospheric CO2, which offer complementary information to the accurate and precise but inevitably sparse ground-based measurements, can contribute to determine characteristics of the terrestrial carbon sink. It is demonstrated using nearly a decade of SCIAMACHY nadir measurements that years with higher temperatures during the growing season can be robustly associated with larger growth rates in atmospheric CO2 and smaller seasonal cycle amplitudes for northern mid-latitudes. We find linear relationships between warming and CO2 growth as well as seasonal cycle amplitude at the 98 % significance level. The quantitative estimates of the corresponding covariations are consistent with those from the CarbonTracker data assimilated CO2 product, indicating that the temperature dependence of the model surface fluxes is realistic. The derived results suggest that the terrestrial carbon sink is less efficient at higher temperatures during the analysed time period. Unless the biosphere has the ability to adapt its carbon storage under warming conditions in the longer term, such a temperature response entails the risk of potential future sink saturation via a positive carbon-climate feedback.

  14. MC-PEPTITA: A Monte Carlo model for Photon, Electron and Positron Tracking In Terrestrial Atmosphere—Application for a terrestrial gamma ray flash

    NASA Astrophysics Data System (ADS)

    Sarria, D.; Blelly, P.-L.; Forme, F.

    2015-05-01

    Terrestrial gamma ray flashes are natural bursts of X and gamma rays, correlated to thunderstorms, that are likely to be produced at an altitude of about 10 to 20 km. After the emission, the flux of gamma rays is filtered and altered by the atmosphere and a small part of it may be detected by a satellite on low Earth orbit (RHESSI or Fermi, for example). Thus, only a residual part of the initial burst can be measured and most of the flux is made of scattered primary photons and of secondary emitted electrons, positrons, and photons. Trying to get information on the initial flux from the measurement is a very complex inverse problem, which can only be tackled by the use of a numerical model solving the transport of these high-energy particles. For this purpose, we developed a numerical Monte Carlo model which solves the transport in the atmosphere of both relativistic electrons/positrons and X/gamma rays. It makes it possible to track the photons, electrons, and positrons in the whole Earth environment (considering the atmosphere and the magnetic field) to get information on what affects the transport of the particles from the source region to the altitude of the satellite. We first present the MC-PEPTITA model, and then we validate it by comparison with a benchmark GEANT4 simulation with similar settings. Then, we show the results of a simulation close to Fermi event number 091214 in order to discuss some important properties of the photons and electrons/positrons that are reaching satellite altitude.

  15. The non-homogeneous accumulation model for terrestrial planet formation and the consequences for the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Turekian, K. K.; Clark, S. P., Jr.

    1975-01-01

    The nonhomogeneous-accumulation model for the formation of the terrestrial planets is described, and its consequences for the formation of the Venusian atmosphere are assayed in the context of our knowledge of the composition of the earth and carbonaceous chondrites. The relative abundances of the low-temperature condensibles in the reservoirs at the earth's surface are applied to Venus. Although carbonaceous chondrites show similar properties for the chemically bound elements, they show large deficiencies for the rare gases. The major gases on Venus, by volume, are predicted to be 98.12% CO2, 1.86% N2 and 0.02% Ar-40.

  16. 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.

  17. Photochemistry in terrestrial exoplanet atmospheres. III. Photochemistry and thermochemistry in thick atmospheres on super Earths and mini Neptunes

    SciTech Connect

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

    2014-03-20

    Some super Earths and mini Neptunes will likely have thick atmospheres that are not H{sub 2}-dominated. We have developed a photochemistry-thermochemistry kinetic-transport model for exploring the compositions of thick atmospheres on super Earths and mini Neptunes, applicable for both H{sub 2}-dominated atmospheres and non-H{sub 2}-dominated atmospheres. Using this model to study thick atmospheres for wide ranges of temperatures and elemental abundances, we classify them into hydrogen-rich atmospheres, water-rich atmospheres, oxygen-rich atmospheres, and hydrocarbon-rich atmospheres. We find that carbon has to be in the form of CO{sub 2} rather than CH{sub 4} or CO in a H{sub 2}-depleted water-dominated thick atmosphere and that the preferred loss of light elements from an oxygen-poor carbon-rich atmosphere leads to the formation of unsaturated hydrocarbons (C{sub 2}H{sub 2} and C{sub 2}H{sub 4}). We apply our self-consistent atmosphere models to compute spectra and diagnostic features for known transiting low-mass exoplanets GJ 1214 b, HD 97658 b, and 55 Cnc e. For GJ 1214 b, we find that (1) C{sub 2}H{sub 2} features at 1.0 and 1.5 ?m in transmission and C{sub 2}H{sub 2} and C{sub 2}H{sub 4} features at 9-14 ?m in thermal emission are diagnostic for hydrocarbon-rich atmospheres; (2) a detection of water-vapor features and a confirmation of the nonexistence of methane features would provide sufficient evidence for a water-dominated atmosphere. In general, our simulations show that chemical stability has to be taken into account when interpreting the spectrum of a super Earth/mini Neptune. Water-dominated atmospheres only exist for carbon to oxygen ratios much lower than the solar ratio, suggesting that this kind of atmospheres could be rare.

  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. 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 lacking1 that increasing CO240 pressure (total atmospheric pressure, P) is enough to raise early Mars mean

  20. Implications of isotopic signatures of noble gases for the origin and evolution of terrestrial atmospheres

    NASA Technical Reports Server (NTRS)

    Rao, A. S. P.

    1987-01-01

    It is contented that the initial quantities of noble gases present in planetesimals were controlled by the sizes and masses of the planets, and fit with a model of successive accretion. The successive accretion model proposed for the origin of terrestrial planets is based upon: (1) the sequence of zones of condensation of solar nebula, (2) the condensation sequence of minerals, iron and nickel in different P-T regimes of the solar nebula, and (3) the sequence in the nucleation of iron cores of the terrestrial planets.

  1. Increasing retention of early career female atmospheric scientists

    NASA Astrophysics Data System (ADS)

    Edwards, L. M.; Hallar, A. G.; Avallone, L. M.; Thiry, H.

    2010-12-01

    Atmospheric Science Collaborations and Enriching NeTworks (ASCENT) is a workshop series designed to bring together early career female scientists in the field of atmospheric science and related disciplines. ASCENT uses a multi-faceted approach to provide junior scientists with tools that will help them meet the challenges in their research and teaching career paths and will promote their retention in the field. During the workshop, senior women scientists discuss their career and life paths. They also lead seminars on tools, resources and methods that can help early career scientists to be successful and prepared to fill vacancies created by the “baby boomer” retirees. Networking is a significant aspect of ASCENT, and many opportunities for both formal and informal interactions among the participants (of both personal and professional nature) are blended in the schedule. The workshops are held in Steamboat Springs, Colorado, home of a high-altitude atmospheric science laboratory, Storm Peak Laboratory, which also allows for nearby casual outings and a pleasant environment for participants. Near the conclusion of each workshop, junior and senior scientists are matched in mentee-mentor ratios of two junior scientists per senior scientist. Post-workshop reunion events are held at national scientific meetings to maintain connectivity among each year’s participants, and for collaborating among participants of all workshops held to date. Evaluations of the two workshop cohorts thus far conclude that the workshops have been successful in achieving the goals of establishing and expanding personal and research-related networks, and that seminars have been useful in creating confidence and sharing resources for such things as preparing promotion and tenure packages, interviewing and negotiating job offers, and writing successful grant proposals.

  2. 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.

  3. 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.

  4. Reducing Uncertainty in Terrestrial Biosphere Models with Satellite Observations of Atmospheric CO2: Comparing MsTMIP with GOSAT

    NASA Astrophysics Data System (ADS)

    Swetish, J. B.; Huntzinger, D. N.; Schwalm, C. R.; Fisher, J. B.; Liu, J.; Michalak, A. M.; Bowman, K. W.

    2014-12-01

    Global-scale terrestrial biosphere models (TBMs) vary in their underlying driving assumptions, inputs, and parameterizations. As a result, TBM estimates of carbon fluxes and pools vary greatly and the lack of direct observations of land-atmosphere carbon exchange at the same spatio-temporal resolution (e.g., 0.5° x 0.5° degree and sub-daily to monthly) of model estimates makes it difficult to assess TBM performance in terms of their ability to represent the terrestrial carbon cycle. Atmospheric CO2 measurements, however, may be a potentially powerful observational constraint for TBMs because they provide an integrated view of surface sources and sinks of carbon. The Greenhouse Gases Observing Satellite (GOSAT) measures atmospheric CO2 from space at spatio-temporal scales relatively consistent with model estimates. Using TBM estimates from the North American Carbon Program Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP), together with estimates of fossil fuel emissions and air-sea fluxes, we translate surfaces fluxes into atmospheric CO2 concentrations using the GEOS-Chem atmospheric transport model. The performance of MsTMIP TBMs is evaluated by comparing the dry air column-averaged mole fractions of CO2 (?CO2) from transported surface fluxes to observations of ?CO2 from GOSAT. While MsTMIP ?CO2 signals are generally consistent with GOSAT ?CO2 in the southern hemisphere, MsTMIP and GOSAT XCO2 show profound differences in the northern hemisphere (NH). In general, MsTMIP XCO2 tends to be higher than GOSAT XCO2 at northern latitudes, especially in the NH summer and fall. Looking specifically at regions in the NH, we compare each MsTMIP ?CO2 to GOSAT ?CO2 in terms of its ability to reproduce the spatial distribution, magnitude and timing of the GOSAT ?CO2 seasonal cycle. We use the information derived from the comparison to link model performance with how certain processes are represented within the models themselves, thus aiding in model development and improvement.

  5. 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.

  6. Early evolution of the planets and their atmospheres; Proceedings of the Advanced Study Institute, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, England, March 23-April 3, 1981

    NASA Astrophysics Data System (ADS)

    Parry, J. H.; Runcorn, S. K.

    1982-09-01

    Various topics on the early evolution of planets are discussed. The subjects considered include: planetoid core crystallization and fractionation; implications of terrestrial Ar-40/Ar-36 for atmospheric and mantle evolutionary models; possible pathways for synthesis of prebiotic organic matter; the effects of the lithosphere on mantle convection and evolution; Soret convection and rheology.

  7. 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

  8. 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.

  9. Early warning of atmospheric regime transitions using transfer operators

    NASA Astrophysics Data System (ADS)

    Tantet, Alexis; Dijkstra, Henk

    2015-04-01

    The existence of persistent midlatitude atmospheric regimes, such as blocking events, with time scales larger than 5-10 days and indications of preferred transition paths between them motivates the development of early-warning indicators of regime transitions. Here, we use a barotropic model of the northern midlatitudes winter flow to study such meta-stable regimes. We look at estimates of transfer operators acting on densities evolving on a reduced phase space spanned by the first Empirical Orthogonal Functions of the streamfunction and develop an early-warning indicator of zonal to blocked flow transition. The study of the spectra of transfer operators estimated for different lags reveals a multi-level structure in the flow as well as the effect of memory on the reduced dynamics due to past interactions between the resolved and unresolved variables. The slowest motions in the reduced phase space are thereby found to have time scales larger than 8 days and to behave as Markovian for larger lags. These motions are associated with meta-stable regimes and their transitions and can be detected as almost-invariant sets of the transfer operator. The early-warning indicator is based on the action on an initial density of products of the transfer operators estimated for sufficiently long lags, making use of the semi-group property of these operators and shows relatively good Peirce skill score. 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 as the manifestation of barotropic instability. Finally, 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.

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

    NASA Astrophysics Data System (ADS)

    Jakosky, Bruce; Grebowsky, Joseph; 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 sensors can be thought of as being grouped into instruments measuring different aspects pertaining to the goals of MAVEN. 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 EGU 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. These early results will be presented.

  11. 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.

  12. Meteorite ablation products and their contribution to the atmospheres of terrestrial planets: An experimental study using pyrolysis-FTIR

    NASA Astrophysics Data System (ADS)

    Court, Richard W.; Sephton, Mark A.

    2009-06-01

    We have used a recently developed quantitative pyrolysis-Fourier transform infrared spectroscopy method to measure the production of water and carbon dioxide during 250 °C desorption and 1000 °C gasification steps for a range of carbonaceous chondrites. Greater yields of water and carbon dioxide during gasification are associated with meteorites believed to have experienced more aqueous alteration on their asteroid parent body (i.e. gas yields for petrographic type 1 > type 2 > type 3). Volatile yields most likely reflect quantities of hydrated mineral phases and partially oxidised organic matter. Methane was not detected in the gasification products of the meteorites, allowing an upper limit on its production of around 100 ppm to be calculated based on the sensitivity of the pyrolysis-Fourier transform infrared spectroscopy technique employed. When considered alongside rates of infall of cosmic dust throughout Earth history, the data can be used to evaluate the production of volatiles during the thermal ablation of dust upon atmospheric entry, and to estimate their contribution to a terrestrial planet's atmosphere and hydrosphere. Over the long term, it appears that contributions of this nature to the Earth's volatile inventory are small, although production rates are calculated to have been substantially higher before and during the Late Heavy Bombardment of 3.8-4.0 Ga. Moreover, ablation of carbonaceous chondritic material does not appear to be a plausible source of the atmospheric methane budget of Mars.

  13. Sub-millimeter observations of the terrestrial atmosphere during an Earth flyby of the MIRO sounder on the Rosetta spacecraft

    NASA Astrophysics Data System (ADS)

    Jiménez, C.; Gulkis, S.; Beaudin, G.; Encrenaz, T.; Eriksson, P.; Kamp, L.; Lee, S.; Buehler, S. A.

    2013-07-01

    Sub-millimeter spectra recorded by the MIRO sounder aboard the Rosetta spacecraft have been used at the time of an Earth flyby (November 2007) to check the consistency and validity of the instrumental data. High-resolution spectroscopic data were recorded in 8 channels in the vicinity of the strong water line at 557 GHz, and in a broad band continuum channel at 570 GHz. An atmospheric radiative transfer code (ARTS) and standard terrestrial atmospheres have been used to simulate the expected observational results. Differences with the MIRO spectra suggest an anomaly in the behavior of four spectroscopic channels. Further technical investigations have shown that a large part of the anomalies are associated with an instability of one of the amplifiers. The quality of the MIRO data has been further tested by inverting the spectra with an atmospheric inversion tool (Qpack) in order to derive a mesospheric temperature profile. The retrieved profile is in good agreement with the one inferred from the Earth Observing System Microwave Limb Sounder (EOS-MLS). This work illustrates the interest of validating instruments aboard planetary or cometary spacecraft by using data acquired during Earth flybys.

  14. A Molecular Approach to the Study of Green Algal Evolution and Early Terrestrial Ecosystems

    Microsoft Academic Search

    R. B. Kodner; R. E. Summons; A. H. Knoll

    2004-01-01

    The biological nature of pre-land plant terrestrial ecosystems remains an enigmatic chapter of the history of life on earth due to lack of fossil evidence. Molecular phylogenies have shown that Charophycean green algae are the closest relatives of the bryophytes, which have been hypothesized to be the earliest divergent land plants. However, there is no fossil evidence to support this

  15. 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

  16. Bubble stability in vigorous convection: Ramifications for magma-ocean degassing and formation of an early atmosphere

    NASA Astrophysics Data System (ADS)

    Sethian, J.; Suckale, J.; Elkins-Tanton, L. T.

    2009-12-01

    The heat provided by energetic impacts, radioactive decay and core formation during the early stages in terrestrial planet evolution is sufficient to melt a silicate mantle partially or entirely. Thus, magma-ocean models provide an interesting hypothetical starting point for understanding mantle evolution of terrestrial planets. A key constraint in these models is the formation of an early atmosphere, because it exerts a strong control over the heat flux from the planetary surface. One open question in the task of developing a model of early atmosphere formation is related to when volatiles begin to exsolve from the magma ocean and in what quantities. Even magma oceans with initial minute water or carbon contents will eventually, as they solidify, become saturated and begin to exsolve volatiles as gases. The bubble size distribution in the magma is likely to exert a strong control over this process: small gas bubbles will tend to remain entrained in vigorous convection while large bubbles decouple from the surrounding flow field and rise to the surface under their own buoyancy. In this paper, we use numerical simulations of two-phase flow to investigate how the size distribution of gas bubbles in a magma ocean depends on its physical characteristics, such as composition, magma viscosity and volatile content. The numerical technique couples a level-set-based representation of the interface to a Navier-Stokes solver through the construction of extension velocities. Preliminary results indicate that gas bubbles in superliquidus magma oceans with low viscosity remain small. In fact, current estimates of the radius at which gas bubbles cease to be entrained in flow and begin to rise to the free surface under their buoyancy might exceed the radius of stable gas bubbles. This observation implies that the earliest atmospheres might form only during the final stages of magma-ocean solidification and possibly through very rapid degassing of oversaturated magma. Late, rapid degassing from a putative terrestrial magma ocean, for example following a Moon-forming impact, implies that solidification of magma oceans would have been exceptionally fast. Rapid interior cooling in turn makes the time to clement surface conditions rapid, preparing the planetary surface for liquid water.

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

    E-print Network

    Manning, Craig

    for the evolution of the early Precambrian atmosphere Codi Lazar a, , Thomas M. McCollom b , Craig E. Manning 2012 Editor: J. Fein Keywords: Abiotic methanogenesis Serpentinization Precambrian atmosphere Faint productive in the early Precambrian when komatiitic volcanism delivered a much larger propor- tion

  18. 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

  19. Journal of Atmospheric and Solar-Terrestrial Physics 66 (2004) 17671778 A decadal solar effect in the tropics in JulyAugust

    E-print Network

    Meehl, Gerald A.

    2004-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 66 (2004) 1767­1778 A decadal solar effect 1978 makes possible an investigation of the influence of the decadal solar oscillation in the tropics during three solar maxima and two solar minima. The NCEP/NCAR reanalyses starting in the 1950s allows

  20. Journal of Atmospheric and Solar-Terrestrial Physics 70 (2008) 10461055 The response in the Pacific to the sun's decadal peaks and

    E-print Network

    Meehl, Gerald A.

    2008-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 70 (2008) 1046­1055 The response. Coupled air­sea response to solar forcing in the Pacific region during northern winter. Journal is sensitive to the influence of the sun in its decadal peaks. We extend this study by three solar peaks

  1. Ann. Geophysicae 14, 1103--1110 (1996) EGS --Springer-Verlag 1996 Detection of nitric acid and nitric oxides in the terrestrial atmosphere

    E-print Network

    Paris-Sud XI, Université de

    1996-01-01

    Ann. Geophysicae 14, 1103--1110 (1996) EGS -- Springer-Verlag 1996 Detection of nitric acid observations of the vertical distributions and the column densities of nitric acid and nitric oxide concentra and nitric oxides in the terrestrial atmosphere in the middle-infrared spectral region M. I. Ble11 cka, M. De

  2. Development of a model of atmospheric oxygen variations to estimate terrestrial carbon storage and release

    NASA Technical Reports Server (NTRS)

    Najjar, Raymond G.; Keeling, Ralph F.; Erickson, David J., III

    1995-01-01

    Two years of work has been completed towards the development of a model of atmospheric oxygen variations on seasonal to decadal timescales. During the first year we (1) constructed a preliminary monthly-mean climatology of surface ocean oxygen anomalies, (2) began modeling studies to assess the importance of short term variability on the monthly-mean oxygen flux, and (3) conducted preliminary simulations of the annual mean cycle of oxygen in the atmosphere. Most of the second year was devoted to improving the monthly mean climatology of oxygen in the surface ocean.

  3. Hard X-rays Irradiated from the Nocturnal Terrestrial Atmosphere: Experiment on CORONAS-F

    NASA Astrophysics Data System (ADS)

    Gusev, Anatoly; Arkhangelsky, Andrey; Kotov, Yury; Gusev, Anatoly; Pankov, Vladislav; Prokhin, Vladimir

    A gamma-ray spectrometer, ABC, onboard the low Earth orbit CORONAS-F satellite monitored solar gamma-rays in the energy range 100keV - to 250 MeV during July 2001 through June 2005 using a CsI detector shielded with plastic scintillator. The device was directed to the Sun. It registered the hard X-rays from the upper atmosphere at shadowed parts of the spacecraft orbit. The global maps of the nocturnal atmosphere emission in hundreds keV energy range are presented. The maps reflect the dynamics of the emission practically from maximum to minimum solar activity.

  4. ~) Pergamon Journal of Atmospheric and Terrestrial Physics, Vol. 57, No. 4, pp. 333 365, 1995

    E-print Network

    Jackman, Charles H.

    and long term solar UV variations: analysis of observations and 2D model results ERIC L. FLEMING atmospheric response to the 27-day and 11-yr solar UV flux variations at low to middle latitudes using a two.51% per 1% change in 205 nm flux. The model also reproduced the observed transition to a negative phase

  5. 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

  6. 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

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

    PubMed Central

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

    2014-01-01

    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

  8. 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

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

    E-print Network

    Misra, Amit; Claire, Mark; Crisp, Dave

    2013-01-01

    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 lev...

  10. Features of the ocean-atmosphere exchange and its effect on terrestrial climate conditions

    NASA Astrophysics Data System (ADS)

    Kartushinsky, A.; Sashko, L.

    The climatic changes on Earth are to a large extent influenced by the intensity of ocean-atmosphere-land interactions Energy exchange in the atmosphere-ocean system depends on the transfer of warm and cold water masses by stream flows Interaction of water masses leads to formation of frontal zones with high temperature gradients Such zones are easily detected by temperature gradients which are calculated according to AVHRR MCSST satellite data for the 1982 -- 1986 average monthly and 1990 -- 2001 average weekly periods The spatial extension and the size of the frontal zone formed by Gulf Stream in North Atlantic affects the evaporation mode Such interaction with atmosphere leads to changes in the cyclonic and anticyclonic activity in the North Atlantic Oscillation NAO zone In this work the seasonal North Atlantic Oscillations are compared with the temperature gradients in North Atlantic for the period of satellite measurements Besides the investigation is made of the connection between the changes of NAO and climatic parameters overland We used the weather stations data concerning the average monthly air temperature and precipitation for the territory of Eurasia for the period of 1900-2004 This work analyses the features of ocean-atmosphere interaction and the effect of such interaction on the climatic conditions We developed software for the analysis of climagrams in graphic form in which the air temperature and amount of precipitation are averaged over the whole observation period and also for separate periods The average seasonal

  11. Sensors to record atmospheric and terrestrial information - Principles of collection and analysis

    Microsoft Academic Search

    M. J. Duggin

    1987-01-01

    The general principles and current status of staring and scanning sensors for satellite remote sensing of land and sea surfaces and atmospheric parameters are reviewed. The types of information obtainable in the different spectral bands are indicated; the common characteristics and specific features of sensors are listed in extensive tables and discussed; and a chronological diagram of U.S. meteorological and

  12. The Calculation of Infrared Limb Emission by Ozone in the Terrestrial Middle Atmosphere

    Microsoft Academic Search

    Martin Gerard Mlynczak

    1989-01-01

    The calculation of infrared limb emission from the middle atmosphere to space by ozone in the 9 mum to 11mum spectral region is discussed. The departure from local thermodynamic equilibrium (LTE) in the vibration-rotation bands of ozone is investigated, considering the processes of collisional excitation, collisional quenching, chemical pumping, photochemical reaction loss, radiative emission and radiative absorption. As the database

  13. 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.

  14. Space-borne imaging observation of the terrestrial upper atmosphere by ISS-IMAP

    NASA Astrophysics Data System (ADS)

    Saito, Akinori; Otsuka, Yuichi; Yamamoto, Mamoru; Yamazaki, Atsushi; Yoshikawa, Ichiro; Sakanoi, Takeshi

    ISS-IMAP (Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping) mission is a space-borne mission on the international space station (ISS) to elucidate the mesoscale structures in the ionosphere, the mesosphere, and the plasmasphere by imaging observations. ISS-IMAP measures the following three parameters: (1) distribution of the atmospheric gravity wave in the mesopause (87km), the ionospheric E-region (95km), and the ionospheric F-region (250km) (2) distribution of the ionized atmosphere in the ionospheric F-region (3) distribution of O+ and He+ ions in the ionosphere and plasmasphere. After the initial check outs, its observation was started in October 2012. ISS-IMAP consists of two imaging instruments on the Exposed Facility of Japanese Experiment Module of the International Space Station, EF of ISS-JEM. Visible-light and infrared spectrum imager (VISI) observes the Mesosphere and the Ionosphere. Extra ultraviolet imager (EUVI) observes the Ionosphere and the Plasmasphere. VISI observes the airglow of 730nm (OH, Alt. 85km), 762nm (O2, Alt. 95km), and 630nm (O, Alt. 250km) in the Nadir direction. The global distributions of the airglow structures whose scale size is 50-500km in the nightside of the Mesosphere and the Ionosphere have been obtained by the VISI observation. EUVI measures the resonant scattering of 30.4nm [He+] and 83.4nm [O+]. Its field- of-view is 15 degrees, and points the limb of the Earth to observe the vertical distribution of the ions. The continuous observation of ISS-IMAP started in October 2012. The coordinated observation between ISS-IMAP and the several ground-based instruments have been carried out to elucidate the coupling process between the lower atmosphere and the upper atmosphere by the wave structures in this scale.

  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. Connecting the dots: A versatile terrestrial planet benchmark for the atmospheres of tidally locked Super-Earths

    E-print Network

    Carone, Ludmila; Decin, Leen

    2014-01-01

    We develop a benchmark for quantifying sustained global dynamics in the atmospheres of tidally locked terrestrial planets using the MITgcm core as the basis of a dry 3D-GCM with simplified thermal forcing. Our forcing employs a Newtonian relaxation scheme based on a simple greenhouse model. Our model is of the same conceptional simplicity than the model of Held& Suarez1994 and is thus versatile and computationally fast. As a case study relevant for Super-Earths, we investigate a Gl581g-like planet with Earth-like atmosphere and irradiation, and present all details on the obtained thermodynamics for representative rotation periods of $P_{rot}=10$ days and $P_{rot}=36.5$ days. This provides proof of concept and identifies interesting dynamical features for the rotating regime $3

  17. Climate and year-to-year variability of atmospheric and terrestrial water cycles in the three great Siberian rivers

    NASA Astrophysics Data System (ADS)

    Oshima, Kazuhiro; Tachibana, Yoshihiro; Hiyama, Tetsuya

    2015-04-01

    Among all the rivers that flow into the Arctic Ocean, the Lena, Yenisei, and Ob are the three largest in terms of water discharge (R), and they are a large source of freshwater. We analyzed the R observed at the river mouths and precipitation minus evapotranspiration (P - E) estimated from atmospheric reanalyses. P is a key player in the water cycles of the Siberian rivers, but regional differences of E also affect the long-term means of R and P - E. Climate fields and terrestrial conditions play some roles for the regional differences of P and E. A decomposition analysis of the moisture flux revealed that moisture transport associated with cyclone activity dominates the climatological features of P - E over the Lena, whereas moisture transport associated with seasonal mean winds dominates the features of P - E over the Ob. Both transport processes affect over the Yenisei. Whereas the moisture transports related to the climatological P - E differs among the rivers, P - E variations are mainly affected by the stationary component of moisture transport for all three Siberian rivers. Although previous studies have shown considerable deviations between P - E and R variations, the year to year variations agree very well with each other when appropriate seasonal time lags are taken into account. Comparison with the results of six atmospheric reanalyses indicated that estimations of P - E with the reanalyses produce values comparable to observed Rs and are therefore an effective way to examine the water cycles of the Siberian rivers.

  18. 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.

  19. 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.

  20. Modeling coupled interactions of carbon, water, and ozone exchange between terrestrial ecosystems and the atmosphere. I: model description.

    PubMed

    Nikolov, Ned; Zeller, Karl F

    2003-01-01

    A new biophysical model (FORFLUX) is presented to study the simultaneous exchange of ozone, carbon dioxide, and water vapor between terrestrial ecosystems and the atmosphere. The model mechanistically couples all major processes controlling ecosystem flows trace gases and water implementing recent concepts in plant eco-physiology, micrometeorology, and soil hydrology. FORFLUX consists of four interconnected modules-a leaf photosynthesis model, a canopy flux model, a soil heat-, water- and CO2- transport model, and a snow pack model. Photosynthesis, water-vapor flux and ozone uptake at the leaf level are computed by the LEAFC3 sub-model. The canopy module scales leaf responses to a stand level by numerical integration of the LEAFC3model over canopy leaf area index (LAI). The integration takes into account (1) radiative transfer inside the canopy, (2) variation of foliage photosynthetic capacity with canopy depth, (3) wind speed attenuation throughout the canopy, and (4) rainfall interception by foliage elements. The soil module uses principles of the diffusion theory to predict temperature and moisture dynamics within the soil column, evaporation, and CO2 efflux from soil. The effect of soil heterogeneity on field-scale fluxes is simulated employing the Bresler-Dagan stochastic concept. The accumulation and melt of snow on the ground is predicted using an explicit energy balance approach. Ozone deposition is modeled as a sum of three fluxes- ozone uptake via plant stomata, deposition to non-transpiring plant surfaces, and ozone flux into the ground. All biophysical interactions are computed hourly while model projections are made at either hourly or daily time step. FORFLUX represents a comprehensive approach to studying ozone deposition and its link to carbon and water cycles in terrestrial ecosystems. PMID:12713923

  1. A Molecular Approach to the Study of Green Algal Evolution and Early Terrestrial Ecosystems

    NASA Astrophysics Data System (ADS)

    Kodner, R. B.; Summons, R. E.; Knoll, A. H.

    2004-12-01

    The biological nature of pre-land plant terrestrial ecosystems remains an enigmatic chapter of the history of life on earth due to lack of fossil evidence. Molecular phylogenies have shown that Charophycean green algae are the closest relatives of the bryophytes, which have been hypothesized to be the earliest divergent land plants. However, there is no fossil evidence to support this relationship nor is there a reliable fossil record of the earliest land plants. Microfossils representing the earliest land plants appear to have a bryophytes affinity based on limited morphological comparisons but this remains controversial. We are applying a biomolecular approach to study both green algal evolution and its relation to bryophytes using the resistant biopolymer algaenan and phytosterols as biological markers. Algaenan has been shown to have high preservation potential and may be the primary component of enigmatic microfossils assumed to be of algal origin. Algaenan and the green algal sterols, stigmasterol and sitosterol, may also be the precursors of n-alkanes and the hydrocarbon stigmastane that are major components of many Neoproterozoic bitumens. The biological nature and phylogenetic distribution of algaenan is still not well understood. Here we explore the presence and structure of algaenans in terrestrial green algae and bryophytes in relation to their phylogenetic distributions.

  2. Early terrestrial impact events: Archean spherule layers in the Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Ozdemir, Seda; Koeberl, Christian; Schulz, Toni; Reimold, W. Uwe; Hofmann, Axel

    2015-04-01

    In addition to the oldest known impact structure on Earth, the 2.02-billion-year-old Vredefort Structure in South Africa, the evidence of Early Earth impact events are Archean spherule beds in South Africa and Australia. These spherules have been interpreted as condensation products from impact plumes and molten impact ejecta or/and impact ejecta that were melted during atmospheric re-entry [e.g., 1,2]. The 3.2-3.5 Ga spherule layers in the Barberton Greenstone Belt in South Africa currently represent the oldest known remnants of impact deposits on Earth. Aiming at identification of extraterrestrial components and to determine the diagenetic and metamorphic history of spherule layer intersections recently recovered in the CT3 drill core from the northeastern part of the Barberton Greenstone Belt, we have studied samples from these layers in terms of petrography and geochemistry. All samples, including spherule layer intersections and intercalating country rocks, were studied for mineral identification by optical and electron microscopy, as well as electron microprobe analysis (EPMA) at Natural History Museum Vienna and Museum für Naturkunde Berlin (MfN). Major and trace element compositions were determined via X-ray fluorescence spectrometry at MfN and instrumental neutron activation analysis (INAA) at University of Vienna. Os isotopes were measured by thermal ionization mass spectrometry (N-TIMS) at University of Vienna. Eighteen spherule beds are distributed over 150 meter drill core in CT3. Spherules are variably, deformed or undeformed. The high number of these layers may have been caused by tectonic duplication. Spherule beds are intercalated with shale, chert, carbonate, and/or sulfide deposits (country rocks). The size range of spherules is 0.5 to 2 mm, and some layers exhibit gradation. Shapes of spherules differ from spherical to ovoid, as well as teardrops, and spherules commonly show off-center vesicles, which have been interpreted as a primary characteristic pointing toward an impact origin [3]. Mineralogical and petrographic studies indicate that most of the mineralogy of the spherule layers is secondary due to secondary overprint by alteration and metamorphism. The mineral assemblages comprise quartz, K-feldspar, various muscovite types, phyllosilicates, Mg-siderite, Ti/Fe-Ti oxides, sulfides such as pyrite, pyrrhotite, chalkopyrite, sphalerite, and galena. INAA data show that some spherule layer intersections have extremely high siderophile element contents, with up to 1.60 wt% Ni, 0.69 wt% Cr, 0.05 wt% Co, 2.06 ppm Ir and 0.02 ppm Au, which is considered extraterrestrial component. This is further supported by their chondritic to slightly supercondritic 187Os/188Os ratios (ranging from 0.11 to 0.19), contrasting more radiogenic values of the spherule layer intercalations in comparison to country rocks, and Os concentrations up to ~4312 ppb. References: [1] Artemieva, N.A., and Simonson, B.M., 2012, LPSC 43, abstract #1372. [2] Johnson, B.C., and Melosh, H.J., 2014, Icarus, 228, 347-363. [3] Glass, B.P. and Simonson, B.M., 2012, Elements 8, 15-60.

  3. Time evolution of ionization effect due to cosmic rays in terrestrial atmosphere during GLE 70

    NASA Astrophysics Data System (ADS)

    Mishev, A. L.; Velinov, P. I. Y.

    2015-07-01

    In the last years the possible effect of solar variability on atmospheric physics and chemistry is highly debated. In most of the proposed models the role of ion production in the atmosphere due to cosmic rays is significant. At present, effects on minor constituents and aerosols are observed over polar regions during major solar events. According to recent findings for such a study it is necessary an essential increase of ion production, specifically during the winter season. Therefore, the ground level enhancement on 13th of December 2006 is appropriate for such a study. Here, we compute the ion production on 13th of December 2006 on the basis of a full target model based on Monte Carlo simulations. The ion production is computed on a step ranging from 10 to 30 min throughout the event. The spectral and angular characteristics of the solar protons are explicitly considered as well as their time evolution. The ionization effect is computed at several altitudes above the sea level, namely 25 km, 18 km, 15 km, 12 km and 8 km in a sub-polar a and polar region, where the effect is maximal. Several applications of the obtained results are discussed.

  4. On the emission of amines from terrestrial vegetation in the context of atmospheric new particle formation

    NASA Astrophysics Data System (ADS)

    Neftel, Albrecht; Sintermann, Jörg

    2015-04-01

    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. 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.

  5. 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.

  6. Can we reconcile atmospheric estimates of the Northern terrestrial carbon sink with land-based accounting?

    SciTech Connect

    Ciais, Philippe [Laboratoire des Sciences du Climat et de l'Environement, France; Luyssaert, Sebastiaan [National Center for Scientific Research, Gif-sur-Yvette, France; Chevallier, Fredric [National Center for Scientific Research, Gif-sur-Yvette, France; Poussi, Zegbeu [National Center for Scientific Research, Gif-sur-Yvette, France; Peylin, Philippe [National Center for Scientific Research, Gif-sur-Yvette, France; Breon, Francois-Marie [National Center for Scientific Research, Gif-sur-Yvette, France; Canadell, J.G. [CSIRO Marine and Atmospheric Research; Shvidenko, Anatoly [IIASA, Laxenburg, Austria; Jonas, Matthias [IIASA, Laxenburg, Austria; King, Anthony Wayne [ORNL; Schulze, E.-D. [Max Planck Institute for Biogeochemistry; Roedenbeck, Christian [Max Planck Institute for Biogeochemistry; Piao, Shilong [Peking University; Peters, Wouter [Wageningen University and Research Centre, The Netherlands

    2010-10-01

    We estimatethenorthernhemisphere(NH)terrestrialcarbon sink bycomparingfourrecentatmosphericinversionswith land-based Caccountingdataforsixlargenorthernregions. The meanNHterrestrialCO2 sink fromtheinversionmodelsis 1.7 PgCyear1 over theperiod2000 2004. Theuncertaintyof this estimateisbasedonthetypicalindividual(1-sigma) precision ofoneinversion(0.9PgCyear1) andisconsistent with themin max rangeofthefourinversionmeanestimates (0.8 PgCyear1). Inversionsagreewithintheiruncertaintyfor the distributionoftheNHsinkofCO2 in longitude,withRussia being thelargestsink.Theland-basedaccountingestimateof NH carbonsinkis1.7PgCyear1 for thesumofthesixregions studied. The1-sigmauncertaintyoftheland-basedestimate (0.3 PgCyear1) issmallerthanthatofatmosphericinversions, but noindependentland-basedfluxestimateisavailableto derive a betweenaccountingmodel uncertainty. Encouragingly, thetop-downatmosphericandthebottom-up land-based methodsconvergetoconsistentmeanestimates within theirrespectiveerrors,increasingtheconfidenceinthe overall budget.Theseresultsalsoconfirmthecontinuedcritical role ofNHterrestrialecosystemsinslowingdownthe atmospheric accumulationofanthropogenicCO2

  7. Photochemistry of methane and the formation of hydrocyanic acid (HCN) in the earth's early atmosphere

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.

    1986-01-01

    A one-dimensional photochemical model is used to analyze the photochemistries of CH4 and HCN in the primitive terrestrial atmosphere. CH4, N2, and HCN photolysis are examined. The background atmosphere and boundary conditions applied in the analysis are described. The formation of HCN as a by-product of N2 and CH4 photolysis is investigated; the effects of photodissociation and rainfall on HCN is discussed. The low and high CH4 mixing ratios and radical densities are studied.

  8. Impacts and atmospheric erosion on the early Earth

    NASA Technical Reports Server (NTRS)

    Vickery, A. M.

    1991-01-01

    It was suggested that heating and/or vaporization of accreting carbonaceous-chondrite-type planetestimals could result in the release of their volatile components. Modeling of this process strongly suggests that substantial atmospheres/hydrospheres could develop this way. During most of the accretionary process, impact velocities generally differed from the escape velocity of the growing proto-planet because most of the collisions were between bodies in nearly matching orbits. Toward the end of accretion, however, collisions were rarer but more energetic, involving large planetestimals and higher impact velocities. Such impacts result in a net loss of atmosphere from a planet, and the cumulative effect impacts during the period of heavy bombardment might have dramatically depleted the original atmospheres. Models developed to study atmospheric erosion by impacts on Mars and the interaction of the vapor plume produced by KT impactor on Earth are applied to the case of the evolution of Earth's atmosphere.

  9. 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.

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

    Microsoft Academic Search

    D. R. Greenwood; J. Eldrett

    2006-01-01

    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

  11. 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

  12. Effect of O3 on the atmospheric temperature structure of early Mars

    E-print Network

    von Paris, P; Godolt, M; Grenfell, J L; Stracke, B; Rauer, H

    2015-01-01

    Ozone is an important radiative trace gas in the Earth's atmosphere. The presence of ozone can significantly influence the thermal structure of an atmosphere, and by this e.g. cloud formation. Photochemical studies suggest that ozone can form in carbon dioxide-rich atmospheres. We investigate the effect of ozone on the temperature structure of simulated early Martian atmospheres. With a 1D radiative-convective model, we calculate temperature-pressure profiles for a 1 bar carbon dioxide atmosphere. Ozone profiles are fixed, parameterized profiles. We vary the location of the ozone layer maximum and the concentration at this maximum. The maximum is placed at different pressure levels in the upper and middle atmosphere (1-10 mbar). Results suggest that the impact of ozone on surface temperatures is relatively small. However, the planetary albedo significantly decreases at large ozone concentrations. Throughout the middle and upper atmospheres, temperatures increase upon introducing ozone due to strong UV absorpt...

  13. Faunal reorganisation in terrestrial mammalian communities: evidence from France during the Lateglacial-Early Holocene transition

    NASA Astrophysics Data System (ADS)

    Bridault, Anne

    2010-05-01

    The Lateglacial-Early Holocene transition is characterized by rapid oscillations between warm and cold episodes. Their impact on ecosystem dynamics was particularly pronounced in north-western Europe where hunter-gatherer societies experienced a succession of environmental transformations, including the expansion and dispersal of biotic communities and changing herbivore habitats. Recent archaeozoological studies and AMS direct dating on mammalian bones/or bone collagen allow to map and precise this process at a supra-regional scale (France). At regional scales (i.e. Paris Basin & Jura-Northern French Alps), results indicate a rapid faunal reorganisation at the end of Lateglacial that will be presented in detail. Composition of faunal assemblages remains then unchanged during the Early Holocene. By contrast, significant herbivore habitat changes are recorded during the Early Holocene by other proxies (pollen data and isotopic data) and a decrease in Red Deer size through time is evidenced by osteometrical analyses. Hypotheses regarding the kind of adaptation process experienced by the faunal communities through time will be presented. Factors that may have controlled the observed changes will be discussed.

  14. Carbon dioxide clouds in an early dense Martian atmosphere

    Microsoft Academic Search

    Anthony Colaprete; Owen B. Toon

    2003-01-01

    We use a time-dependent, microphysical cloud model to study the formation of carbon dioxide clouds in the Martian atmosphere. Laboratory studies by Glandorf et al. [2002] show that high critical supersaturations are required for CO2 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

  15. Volatile inventory and early evolution of the planetary atmospheres

    Microsoft Academic Search

    Mikhail Ya. Marov; Sergei I. Ipatov

    2001-01-01

    Formation of atmospheres of the inner planets involved the concurrent processes of mantle degassing and collisions that culminated during the heavy bombardment. Volatile-rich icy planetesimals impacting on the planets as a late veneer strongly contributed to the volatile inventory. Icy remnants of the outer planet accretion significantly complemented the accumulation of the lithophile and atmophile elements forced out onto the

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. MODIS-Derived Terrestrial Primary Production

    NASA Astrophysics Data System (ADS)

    Zhao, Maosheng; Running, Steven; Heinsch, Faith Ann; Nemani, Ramakrishna

    Temporal and spatial changes in terrestrial biological productivity have a large impact on humankind because terrestrial ecosystems not only create environments suitable for human habitation, but also provide materials essential for survival, such as food, fiber and fuel. A recent study estimated that consumption of terrestrial net primary production (NPP; a list of all the acronyms is available in the appendix at the end of the chapter) by the human population accounts for about 14-26% of global NPP (Imhoff et al. 2004). Rapid global climate change is induced by increased atmospheric greenhouse gas concentration, especially CO2, which results from human activities such as fossil fuel combustion and deforestation. This directly impacts terrestrial NPP, which continues to change in both space and time (Melillo et al. 1993; Prentice et al. 2001; Nemani et al. 2003), and ultimately impacts the well-being of human society (Milesi et al. 2005). Additionally, substantial evidence show that the oceans and the biosphere, especially terrestrial ecosystems, currently play a major role in reducing the rate of the atmospheric CO2 increase (Prentice et al. 2001; Schimel et al. 2001). NPP is the first step needed to quantify the amount of atmospheric carbon fixed by plants and accumulated as biomass. Continuous and accurate measurements of terrestrial NPP at the global scale are possible using satellite data. Since early 2000, for the first time, the MODIS sensors onboard the Terra and Aqua satellites, have operationally provided scientists with near real-time global terrestrial gross primary production (GPP) and net photosynthesis (PsnNet) data. These data are provided at 1 km spatial resolution and an 8-day interval, and annual NPP covers 109,782,756 km2 of vegetated land. These GPP, PsnNet and NPP products are collectively known as MOD17 and are part of a larger suite of MODIS land products (Justice et al. 2002), one of the core Earth System or Climate Data Records (ESDR or CDR).

  4. Net exchanges of CO2, CH4, and N2O between China's terrestrial ecosystems and the atmosphere and their contributions to global climate warming

    NASA Astrophysics Data System (ADS)

    Tian, Hanqin; Xu, Xiaofeng; Lu, Chaoqun; Liu, Mingliang; Ren, Wei; Chen, Guangsheng; Melillo, Jerry; Liu, Jiyuan

    2011-06-01

    China's terrestrial ecosystems have been recognized as an atmospheric CO2 sink; however, it is uncertain whether this sink can alleviate global warming given the fluxes of CH4 and N2O. In this study, we used a process-based ecosystem model driven by multiple environmental factors to examine the net warming potential resulting from net exchanges of CO2, CH4, and N2O between China's terrestrial ecosystems and the atmosphere during 1961-2005. In the past 45 years, China's terrestrial ecosystems were found to sequestrate CO2 at a rate of 179.3 Tg C yr-1 with a 95% confidence range of (62.0 Tg C yr-1, 264.9 Tg C yr-1) while emitting CH4 and N2O at rates of 8.3 Tg C yr-1 with a 95% confidence range of (3.3 Tg C yr-1, 12.4 Tg C yr-1) and 0.6 Tg N yr-1 with a 95% confidence range of (0.2 Tg N yr-1, 1.1 Tg N yr-1), respectively. When translated into global warming potential, it is highly possible that China's terrestrial ecosystems mitigated global climate warming at a rate of 96.9 Tg CO2eq yr-1 (1 Tg = 1012 g), substantially varying from a source of 766.8 Tg CO2eq yr-1 in 1997 to a sink of 705.2 Tg CO2eq yr-1 in 2002. The southeast and northeast of China slightly contributed to global climate warming; while the northwest, north, and southwest of China imposed cooling effects on the climate system. Paddy land, followed by natural wetland and dry cropland, was the largest contributor to national warming potential; forest, followed by woodland and grassland, played the most significant role in alleviating climate warming. Our simulated results indicate that CH4 and N2O emissions offset approximately 84.8% of terrestrial CO2 sink in China during 1961-2005. This study suggests that the relieving effects of China's terrestrial ecosystems on climate warming through sequestering CO2 might be gradually offset by increasing N2O emission, in combination with CH4 emission.

  5. The inception of the oceans and CO 2-atmosphere in the early history of the Earth

    Microsoft Academic Search

    Lin-Gun Liu

    2004-01-01

    After accretion and solidification of a “magma ocean”, the proto-atmosphere of the Earth is modeled to compose of 560 bar of H2O and 100 bar of CO2. The existence of a CO2-rich atmosphere in the early history of the Earth has been envisaged and supported by earlier studies. The results of the present study suggest that the oceans started to

  6. The early Archaean Itsaq Gneiss Complex of southern West Greenland: the importance of field observations in interpreting age and isotopic constraints for early terrestrial evolution

    NASA Astrophysics Data System (ADS)

    Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; Mcgregor, Victor R.

    2000-09-01

    Geochemical and isotopic studies of small volumes of variably preserved? 3600 Ma rocks in gneiss complexes are crucial for documenting early Earth history. In the Itsaq Gneiss Complex of the Nuuk region, West Greenland, there is dispute whether the granitic ( sensu lato) orthogneisses dominating it are mainly products of a single ca. 3650 Ma crust formation "super event," or whether they formed in several unrelated events between ca. 3850 and 3560 Ma. Which of these interpretations of the dates is correct has major implications regarding what the whole rock radiogenic isotopic record (Pb/Pb, Sm/Nd, Rb/Sr) reveals about continental crust formation and early terrestrial differentiation. There is also debate whether some West Greenland metasedimentary rocks with 12C/ 13C data interpreted as evidence for life are? 3850 Ma or only? 3650 Ma old. Establishing the correct age for these rocks is important for debates concerning early surficial environments and origin of life. Controversies have arisen because of different approaches taken by different workers, specifically with respect to how much emphasis is placed on field geology in interpreting dates and isotopic data. In this paper, field observations and sampling from low strain zones, where the origin and geological context of the rocks are best preserved and understood, are closely integrated with U-Pb zircon dates and cathodoluminescence (CL) imagery of the zircons. This approach shows that most single-phase, well-preserved, meta-granitoid samples have simple zircon populations dominated by oscillatory-zoned prismatic grains formed when their host magmas crystallized. On the other hand, migmatites and some strongly deformed-banded gneisses have much more complex zircon populations. The combined field evidence and zircon geochronology on the Itsaq Gneiss Complex demonstrate that 1) some areas contain exposed orthogneisses formed during multiple magmatic/thermal events between ca. 3850 and 3560 Ma and are not (as suggested by Kamber and Moorbath, 1998) dominated by ca. 3650 Ma granitoids containing abundant> 3650 Ma zircons inherited from cryptic, unexposed, older rocks; 2) abundant,? 3750 Ma granitoids are present, which are locally well-preserved; 3) some water-lain sediments reported as showing C isotope evidence for life were deposited as early as 3850 Ma; 4) the whole-rock Sm/Nd isochron approach fails to distinguish with any confidence 3650 Ma from 3800 Ma rocks, 5) however, it reinforces previous indications for markedly depleted (? + 2.5 ? Nd) domains in the pre-3750 Ma mantle.

  7. The Formation of Haze During the Rise of Oxygen in the Atmosphere of the Early Earth

    NASA Astrophysics Data System (ADS)

    Horst, S. M.; Jellinek, M.; Pierrehumbert, R.; Tolbert, M. A.

    2013-12-01

    Atmospheric aerosols play an important role in determining the radiation budget of an atmosphere and can also provide a wealth of organic material to the surface. Photochemical hazes are abundant in reducing atmospheres, such as the N2/CH4 atmosphere of Titan, but are unlikely to form in oxidizing atmospheres, such as the N2/O2 atmosphere of present day Earth. However, information about haze formation in mildly oxidizing atmospheres is lacking. Understanding haze formation in mildly oxidizing atmospheres is necessary for models that wish to investigate the atmosphere of the Early Earth as O2 first appeared and then increased in abundance. Previous studies of the atmosphere of the Early Earth have focused on haze formation in N2/CO2/CH4 atmospheres. In this work, we experimentally investigate the effect of the addition of O2 on the formation and composition of aerosols. Using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (see e.g. [1]) we have obtained in situ composition measurements of aerosol particles produced in N2/CO2/CH4/O2 gas mixtures subjected to FUV radiation (deuterium lamp, 115-400 nm) for a range of initial CO2/CH4/O2 mixing ratios. In particular, we studied the effect of O2 ranging from 2 ppm to 2%. The particles were also investigated using a Scanning Mobility Particle Sizer (SMPS), which measures particle size, number density and mass loading. A comparison of the composition of the aerosols will be presented. The effect of variation of O2 mixing ratio on aerosol production, size, and composition will also be discussed. [1] Trainer, M.G., et al. (2012) Astrobiology, 12, 315-326.

  8. Brain-specific lipids from marine, lacustrine, or terrestrial food resources: potential impact on early African Homo sapiens.

    PubMed

    Broadhurst, C Leigh; Wang, Yiqun; Crawford, Michael A; Cunnane, Stephen C; Parkington, John E; Schmidt, Walter F

    2002-04-01

    The polyunsaturated fatty acid (PUFA) composition of the mammalian central nervous system is almost wholly composed of two long-chain polyunsaturated fatty acids (LC-PUFA), docosahexaenoic acid (DHA) and arachidonic acid (AA). PUFA are dietarily essential, thus normal infant/neonatal brain, intellectual growth and development cannot be accomplished if they are deficient during pregnancy and lactation. Uniquely in the human species, the fetal brain consumes 70% of the energy delivered to it by mother. DHA and AA are needed to construct placental and fetal tissues for cell membrane growth, structure and function. Contemporary evidence shows that the maternal circulation is depleted of AA and DHA during fetal growth. Sustaining normal adult human brain function also requires LC-PUFA.Homo sapiens is unlikely to have evolved a large, complex, metabolically expensive brain in an environment which did not provide abundant dietary LC-PUFA. Conversion of 18-carbon PUFA from vegetation to AA and DHA is considered quantitatively insufficient due to a combination of high rates of PUFA oxidation for energy, inefficient and rate limited enzymatic conversion and substrate recycling. The littoral marine and lacustrine food chains provide consistently greater amounts of pre-formed LC-PUFA than the terrestrial food chain. Dietary levels of DHA are 2.5-100 fold higher for equivalent weights of marine fish or shellfish vs. lean or fat terrestrial meats. Mammalian brain tissue and bird egg yolks, especially from marine birds, are the richest terrestrial sources of LC-PUFA. However, land animal adipose fats have been linked to vascular disease and mental ill-health, whereas marine lipids have been demonstrated to be protective. At South African Capesites, large shell middens and fish remains are associated with evidence for some of the earliest modern humans. Cape sites dating from 100 to 18 kya cluster within 200 km of the present coast. Evidence of early H. sapiens is also found around the Rift Valley lakes and up the Nile Corridor into the Middle East; in some cases there is an association with the use of littoral resources. Exploitation of river, estuarine, stranded and spawning fish, shellfish and sea bird nestlings and eggs by Homo could have provided essential dietary LC-PUFA for men, women, and children without requiring organized hunting/fishing, or sophisticated social behavior. It is however, predictable from the present evidence that exploitation of this food resource would have provided the advantage in multi-generational brain development which would have made possible the advent of H. sapiens. Restriction to land based foods as postulated by the savannah and other hypotheses would have led to degeneration of the brain and vascular system as happened without exception in all other land based apes and mammals as they evolved larger bodies. PMID:11923081

  9. Paleoceanographic Implications of the Terrestrial Carbon-Isotope Record of the Early Toarcian (Jurassic) Oceanic Anoxic Event

    NASA Astrophysics Data System (ADS)

    Hesselbo, S.; Jenkyns, H. C.; Duarte, L. V.

    2005-12-01

    Macrofossil wood in two European sections representing the Toarcian (Early Jurassic) Oceanic Anoxic Event (OAE) have previously been shown to exhibit a large (~ -6 to -7 %) shift in d13C values which has been interpreted as a massive and geologically short-lived perturbation to the global carbon cycle. This interpretation has recently been challenged on the basis of a compilation of carbon-isotope data from belemnites collected from sections in northern Europe that exhibit carbon isotope values that are heavier than expected at the peak of the OAE. Here we present new carbon isotope measurements from wood collected from a marine record of the early Toarcian at Peniche, Portugal, a section currently under consideration as a GSSP for the base of the Toarcian. A large negative excursion (~ -7%) is confirmed for the OAE in these samples. These cannot have been severely impregnated by hydrocarbons of marine origin and the ages are well defined by ammonite biostratigraphy and by Sr-isotope stratigraphy. Carbon-isotope data is also presented for an early diagenetic silica nodule that formed within jet from the Toarcian of the Yorkshire coast, northeast England; values are indistinguishable from those of stratigraphically equivalent jet samples from which solvent extractable hydrocarbons had been removed. Thus, the early Toarcian negative carbon-isotope excursion is confirmed as a phenomenon of the global shallow-ocean, biosphere and atmosphere. It is likely that the anomalously heavy values obtained from belemnites from the OAE interval derive their isotopic signature from localized and possibly seasonal water masses characterized by dissolved inorganic carbon strongly enriched in heavy carbon by very high organic productivity.

  10. Atmospheric carbon dioxide as a driver for deglaciation during the Mi-1 event: new evidence from terrestrial Southern Hemisphere proxies

    NASA Astrophysics Data System (ADS)

    Fox, B.; Wilson, G. S.; Lee, D.; Haworth, M.; Wartho, J.; Kaulfuss, U.; Bannister, J.; Gorman, A. R.; Jones, D. A.; Lindqvist, J.

    2011-12-01

    Foulden Maar is an annually-resolved maar lake deposit dating from the Oligocene/Miocene boundary. The deposit, from the South Island of New Zealand, is the first high-resolution terrestrial record of the O/M boundary and the rapid deglaciation of Antarctica that occurred during the second half of the Mi-1 event. A ~180 m core from the centre of the lake bed comprises ~60 m of basal graded breccias, sands and muds overlain by ~120 m of diatomite punctuated by volcanogenic horizons. The basal siliciclastic sediments contain clasts of basalt and country rock and are interpreted as diatreme breccias coeval with the formation of the maar. The diatomite succession consists of mm-scale light-dark couplets and diatomaceous turbidites. Radiometric dates were obtained from basaltic clasts found at ~110 m depth (close to the base of the diatomite sucession) in a slump deposit of crater wall material. These give ages of 23.45 ± 0.25 Ma and 23.68 ± 0.36 Ma. A nearby basaltic dyke formed during the same episode of volcanism as the maar crater gives a date of 23.17 ± 0.17 Ma. A magnetic reversal occurs at ~106 m depth in the core, constraining the age of this point to 23.34 Ma (the base of chron C6Cn.3n) or 23.03 Ma (the base of chron C6Cn.2n). Spectral analysis of physical properties measurements of the diatomite section of the core reveals obliquity and precessional frequencies. An age model based on these frequencies shows that individual light-dark couplets of diatomite represent annual varves and that the normally magnetised section from ~106 m depth to the top of the core covers ~100,000 years. This rules out C6Cn.3n, which is only 50,000 years long, placing the base of the diatomite succession at the Oligocene-Miocene boundary and the peak of the Mi-1 event. We have collected stomatal index values from Litsea and Podocarpus leaves found in the succession. The Podocarpus values are calibrated using Podocarpus plants grown at various concentrations of carbon dioxide from 380 ppmv to 1500 ppmv. The Litsea values are calibrated using published SI values for various Litsea species of similar morphology and inferred ecology (the NLE approach). Our results show an atmospheric carbon dioxide level of ~400 ppmv at ~23.01 Ma (77 m depth below the top of the core), with concentration increasing to ~800-1200 ppmv at ~22.98 Ma (55 m) and dropping back to ~400-600 ppmv at ~22.9 Ma (0 m, the present-day surface outcrop). This short-lived, rapid increase in atmospheric carbon dioxide concentration coincides with the initiation of the deglaciation phase of the Mi-1 event and implies that CO2 was the driver of this deglaciation.

  11. 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.

  12. 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.

  13. Model atmospheres for novae during the early stages

    SciTech Connect

    Wehrse, R.; Hauschildt, P.H. (Heidelberg Univ. (Germany, F.R.). Inst. fuer Theoretische Astrophysik); Shaviv, G. (Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Physics); Starrfield, S. (Los Alamos National Lab., NM (USA) Arizona State Univ., Tempe, AZ (USA). Dept. of Physics)

    1989-01-01

    Continuum and line blanketing models for the photospheres of novae in the early stages of their outbursts are presented. The expanding envelopes are characterized by a very slow increase of density with decreasing radius which leads to very large geometrical extensions and large temperature differences between the inner and outer parts. The spectra show a large IR excess and a small Balmer jump which may be either in absorption or in emission. For the parameters considered (T{sub eff} = 10{sup 4}, 1.5 {times} 10{sup 4}, 2 {times} 10{sup 4}K, R = 10{sup 11} cm, solar composition), most lines are in absorption. The effects of both modifications in the temperature structure (e.g. by heating from shock fronts) and changes in the abundances of the heavy elements on the emergent spectra are briefly discussed. 13 refs., 11 figs.

  14. The UV-B stimulon of the terrestrial cyanobacterium Nostoc commune comprises early shock proteins and late acclimation proteins.

    PubMed

    Ehling-Schulz, Monika; Schulz, Stefan; Wait, Robin; Görg, Angelika; Scherer, Siegfried

    2002-11-01

    The UV-B and desiccation-tolerant terrestrial cyanobacterium Nostoc commune was grown under defined UV irradiation. Proteome changes were monitored in the membrane and the cytosolic and the extracellular fractions. Tools were developed to separate stress-triggered from growth stage-dependent changes. UV-B changed the relative cellular concentration of 493 out of 1,350 protein spots at least by a factor of three, rendering the UV-B stimulon of N. commune the most complex one described so far. It comprises two different parts: an early shock response influencing 214 proteins and a late acclimation response involving 279 proteins. The shock response comprised many membrane or membrane-associated proteins, whereas the acclimation response mainly changed cytosolic proteins. Most of the shock-induced changes were transient and did not overlap with the acclimation response. In the extracellular fraction, UV irradiation induced superoxide dismutase and the water stress protein. In total, 27 intracellular, UV-B-induced proteins were partially sequenced by electrospray ionization tandem mass spectrometry. Three functional classes were identified: proteins involved in lipid metabolism, in carbohydrate metabolism and in regulatory pathways. About 50% of the sequenced proteins were homologous to cyanobacterial database entries with un-known function. Interestingly, all of these proteins belong to the UV-B acclimation response. We conclude that the UV-B shock response and the UV-B acclimation response represent two completely different and remarkably complex strategies of N. commune to protect itself against UV-B radiation in its natural environment. PMID:12410839

  15. 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.

  16. Coupled noble gas-hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

    E-print Network

    Paris-Sud XI, Université de

    Coupled noble gas-hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation E, the relationship between noble gas photoionization and organic photochemistry has been investigated from efficient that other ionized noble gases trapping and (2) results in a significant enrichment of heavy xenon

  17. LONG-RANGE ATMOSPHERIC TRANSPORT AND DEPOSITION OF ANTHROPOGENIC CONTAMINANTS AND THEIR POTENTIAL EFFECTS ON TERRESTRIAL ECOSYSTEMS

    EPA Science Inventory

    Through the processes of atmospheric transport and deposition, many anthropogenic contaminants such as industrial organics, pesticides, and trace metals have become widely distributed around the globe. ue to the phenomenon of long-range atmospheric transport, even the most remote...

  18. Influence of aerosol source regions and transport pathway on ?D of terrestrial biomarkers in atmospheric aerosols from the East China Sea

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shinya; Kawamura, Kimitaka; Seki, Osamu; Kariya, Tadashi; Lee, Meehye

    2013-04-01

    We measured stable hydrogen isotope ratios (?D) of terrestrial biomarkers (n-alkanes and n-fatty acids) in atmospheric total suspended particles collected at Jeju Island in the East China Sea, from April 2001 to March 2002, to better understand the influence of long-range atmospheric transport on their seasonal variations. The ?D values of the C27, C29 and C31n-alkanes (?DALK) show a significant negative correlation with the CPI values of n-alkanes (r2 = 0.26, p < 0.01), suggesting that the ?DALK variations are partly attributed to a superimposed contribution from fossil fuel hydrocarbons. Seasonal variations in the concentrations of the C22-C28 even-carbon numbered n-fatty acids revealed relatively high concentrations in spring, autumn and winter seasons, in which the air masses are transported from northeast Asia. In contrast, the concentrations are low in summer when the air masses are transported from Southeast Asia and the Pacific. Relatively high C26/FA and low C24/FA ratios in spring, autumn and winter samples suggest that the C26n-fatty acids are more abundantly transported from the Asian continent during these seasons. Seasonal variations in the ?D of the C22-C26 even-carbon numbered n-fatty acids exhibit significant enrichment with D (by ˜40‰) in May and June to August samples, whereas the ?D of the C28n-fatty acids gradually decrease during summer. The magnitude of the ?D offsets (˜45‰) between the C28n-fatty acid and the other homologues are much larger than those observed in East Asia spanning 18°N-50°N latitude (ca. 30‰), suggesting that the decoupling is likely attributed to the mixing of distinct source vegetation with different ?D ratios. Comparison of the weighted-mean ?D values of n-fatty acids (?DFA) between air mass source categories revealed relatively low values (˜-170‰) in samples with trajectories from the northeastern part of the Asian continent, supporting that the ?D analyses may be a powerful tool in deciphering the source regions of terrestrial biomarkers in atmospheric aerosols from the Asian continent. The results of this study provides important implications for paleoclimate studies that the ?D variations of long-range transported terrestrial biomarkers in remote ocean sediments may have recorded past changes in source strengths of the biomarkers and therefore have a potential to reconstruct paleo-wind patterns and transport of terrestrial carbon over the Pacific.

  19. Special issue of Terrestrial, Atmospheric and Oceanic Science, 11(1), 21-52, March 2000. COSMIC System Description

    E-print Network

    System Description C. Rocken, Y.-H. Kuo, W. Schreiner, D. Hunt, S. Sokolovskiy University Corporation that are of considerable importance to the scientific community and to society as a whole. COSMIC is an interdisciplinary regions, and it will enable scientists to monitor the response of #12;Special issue of Terrestrial

  20. Investigating the Early Atmospheres of Earth and Mars through Rivers, Raindrops, and Lava Flows

    NASA Astrophysics Data System (ADS)

    Som, Sanjoy M.

    2010-11-01

    The discovery of a habitable Earth-like planet beyond our solar-system will be remembered as one of the major breakthroughs of 21st century science, and of the same magnitude as Copernicus' heliocentric model dating from the mid 16th century. The real astrobiological breakthrough will be the added results from atmospheric remote sensing of such planets to determine habitability. Atmospheres, in both concentration and composition are suggestive of processes occurring at the planetary surface and upper crust. Unfortunately, only the modern Earth's atmosphere is known to be habitable. I investigate the density and pressure of our planet's early atmosphere before the rise of oxygen 2.5 billion years ago, because our planet was very much alive microbially. Such knowledge gives us another example of a habitable atmosphere. I also investigates the atmosphere of early Mars, as geomorphic signatures on its surface are suggestive of a past where liquid water may have present in a warmer climate, conditions suitable for the emergence of life, compared with today's 6 mbar CO2-dominated atmosphere. Using tools of fluvial geomorphology, I find that the largest river-valleys on Mars do not record a signature of a sustained hydrological cycle, in which precipitation onto a drainage basin induces many cycles of water flow, substrate incision, water ponding, and return to the atmosphere via evaporation. Rather, I conclude that while episodes of flow did occur in perhaps warmer environments, those periods were short-lived and overprinted onto a dominantly cold and dry planet. For Earth, I develop a new method of investigating atmospheric density and pressure using the size of raindrop imprints, and find that raindrop imprints preserved in the 2.7 billion year old Ventersdorp Supergroup of South Africa are consistent with precipitation falling in an atmosphere of near-surface density < 2 kg/m3 and probably > 0.1 kg/m3, compared to a modern value of 1.2 kg/m3, further suggesting a nitrogen level of at most twice present levels and perhaps well below present levels. To constrain this further, I re-evaluate a published paleobarometry technique using the vesicle size-distribution in simply emplaced lava flows and apply it to sea-level erupted lava flows from the 2.7 billion year old Fortescue group of Western Australia. Results from three flows suggest a range for atmospheric pressure 0.07 < Patm < 0.64 atm, which has profound consequences for our interpretation of the history of the nitrogen cycle by implying that the development of the nitrogenase enzyme necessary for nitrogen fixation happened very early on in the development of life.

  1. 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 laser pulses at atmospheric pressure. To describe the laser-target interaction and the plume expansion applications 19,23 . For example, atmospheric pressure matrix-assisted laser desorption ionization AP

  2. Arctic Carbon Storage and Gas Exchange Within and Between a Complex of Terrestrial, Freshwater and Marine Ecosystems and Their Interactions with the Atmosphere

    NASA Astrophysics Data System (ADS)

    Christensen, T. R.

    2012-12-01

    The primary goal of this presentation is to provide a measurement-based analysis of the complex relationships relating to the exchange of radiative active trace gases, carbon dioxide and methane, between different arctic landscape components and between the integrated result of these and the atmosphere. Focus will be on typical Arctic landscapes in Greenland starting at glacier forefields and downslope terrestrial permafrost environments to the limnic ecosystems and ultimately the near coastal environment. The terrestrial ecosystems become gradually more productive towards the coast and the transport of organic material towards the riverine and lake ecosystems gets to be more intensive and also increasingly sensitive to permafrost dynamics. A part of this organic material will be stored in sediments but a part of it will continue out to the coastal systems (Figure 1). A fundamental question is how much of this organic carbon is produced and where along this sequence of linked ecosystem processes the most important interactions with the atmosphere takes place. The answer will vary in time and the temporal aspects of the atmospheric exchanges are an important feature needed for a coherent understanding of arctic ecosystem interactions with climate. Hence, it puts pressure on the time-resolution and continuity of measurements in this complex set of different ecosystems and the degree of challenge this represents also vary between systems. With their upstream catchments Greenlandic terrestrial catchment-fjord ecosystems may form good micro- or mesocosm systems to study as model areas that are relevant for large scale understanding also. Some systems in Greenland such as the Nuuk and Zackenberg areas are at the same time some of the areas in the circumpolar North where the most elaborate relevant data are already being gathered on a continues basis as part of the Greenland Ecosystem Monitoring (GEM) activities. Here we provide a mass-balance approach to the storage, transport and atmospheric exchanges of carbon in sub- and high-arctic Greenlandic fjord ecosystem areas respectively. We review the availability of data to provide such mass balances and also the sensitivity of the individual components to changing climatic conditions.igure 1. Budgeting of the integrated storage and transport of organic carbon and the associated greenhouse gas exchange is essentially about quantifying the pools and arrows in this schematic figure. The objective of this presentation is to assess the spatial dynamics in two Greenlandic fjord systems mainly with the use of monitoring data obtained by GEM (see text).

  3. Terrestrial biogeochemical feedbacks in the climate system

    Microsoft Academic Search

    A. Arneth; S. P. Harrison; S. Zaehle; K. Tsigaridis; S. Menon; P. J. Bartlein; J. Feichter; A. Korhola; M. Kulmala; D. O'Donnell; G. Schurgers; S. Sorvari; T. Vesala

    2010-01-01

    The terrestrial biosphere is a key regulator of atmospheric chemistry and climate. During past periods of climate change, vegetation cover and interactions between the terrestrial biosphere and atmosphere changed within decades. Modern observations show a similar responsiveness of terrestrial biogeochemistry to anthropogenically forced climate change and air pollution. Although interactions between the carbon cycle and climate have been a central

  4. Early Eocene carbon isotope excursions: Evidence from the terrestrial coal seam in the Fushun Basin, Northeast China

    NASA Astrophysics Data System (ADS)

    Chen, Zuoling; Ding, Zhongli; Tang, Zihua; Wang, Xu; Yang, Shiling

    2014-05-01

    A series of transient global warming events between 56 and 50 Ma are characterized by a pronounced negative carbon isotope excursion (CIE). However, the documents of these hyperthermals, such as Eocene Thermal Maximum 2 and H2 events, have come chiefly from marine sediments, and their expression in terrestrial organic carbon is still poorly constrained. Here we yield a high-resolution carbon isotope record of terrestrial organic material from the Fushun Basin, which displays four prominent CIEs with magnitudes larger than 2.5‰. Based on age constraint and comparisons with deep-sea records, our data provide the first evidence of the four hyperthermals in coal seams and suggest a global significance of these events. Moreover, the difference of CIE magnitudes between marine and terrestrial records shows a significant linear correlation with the marine carbonate CIE, implying that these events are likely attributable to recurring injections of 13C-depleted carbon from submarine methane hydrates and/or permafrost.

  5. 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.

  6. 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

  7. 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

  8. Complex spatiotemporal responses of global terrestrial primary production to climate change and increasing atmospheric CO2 in the 21st century.

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    Try, P.

    2002-06-01

    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 climate change. The objectives of the GEWEX Program are to: -- determine the hydrological cycle and energy fluxes by means of global measurements of atmospheric and surface properties; -- model the global hydrological cycle and its impact on the atmosphere, oceans and land surfaces; -- develop the ability to predict the variations of global and regional hydrological processes and water resources, and their response to environmental change; and, -- advance the development of observing techniques, data management, and assimiliation systems for operational application to long-range weather forecasts, hydrology, and climate predictions. The primary activities of GEWEX are a) global data set development, b) process studies, c) model development support. To accomplish this, GEWEX has many components to address the critical elements with roles in the energy and water cycles. The data projects focus on global distribution and variability of clouds, water vapour, aerosols, surface radiation, precipitation and the features of the land surface and near surface meteorology that couple the land to the atmosphere. The modelling projects focus on the cloud, land-atmosphere and boundary layer parameterizations necessary to drive our regional and global predictive models. Coupling the land-atmosphere at the mesoscale has been the initial strategy for GEWEX and five major continental-scale field campaigns have been underway to provide new process and modelling understanding in the Amazon, Baltic Sea, Mississippi River Basin, MacKenzie River Basin, and four basins in Asia (Thailand, Tibet, Siberia and China). A West African campaign is also in the planning stages. All of these GEWEX components have elements that consider and address the carbon aspects of the land-atmosphere interactions and GEWEX has two integrating projects to facilitate these activities: the International Satellite Land Surface Climatology Project (ISLSCP) and the Global Land Atmosphere System Study (GLASS). ISLSCP focuses on the field campaigns, data sets and role of carbon exchange in the land-atmosphere coupling while GLASS focuses on the integration and parameterization of key land-atmosphere features in the full range of modelling activities. The major focus of ISLSCP is to improve our understanding of how carbon, energy and water are exchanged between the atmosphere and the terrestrial biosphere as an important component in understanding and predicting climate change. This is done by ISLSCP with the following objectives: -- Demonstrate the types of surface and near-surface satellite measurements that are relevant to climate and global change studies. -- Develop and improve algorithms for the interpretation of satellite measurements of land-surface features. -- Develop methods to validate area-averaged quantities derived from satellite measurements for climate simulation models. -- Prepare the groundwork for future operational production of landsurface data sets, which can be directly applied to climate problems. GEWEX also plays a vital role in the new WCRP-IGBP-IHDP joint Carbon Initiative and there are a series of new developments that impact the new carbon studies related to the interdisciplinary aspects of coupled land-atmosphere-ocean modelling and global observations. The new satellite spectrometer-interferometer instrumentation, improved land-atmosphere coupling in models and new carbon treatment and transport within global atmospheric models, all relate to the overall need for an improved integrated view of the global carbon-ocean-land-atmosphere interactions based on new observations and modelling techniques. This presentation will update the activities and plans of GEWEX as they

  10. Martian supergene enrichment in Shalbatana Valley: Implications for Mars Early atmosphere

    NASA Astrophysics Data System (ADS)

    Popa, Ciprian; Carrozzo, Giacomo; DiAchille, Gaetano; Silvestro, Simone; Espostio, Francesca; Mennella, Vito

    2015-04-01

    The present work focuses on the detailed description of the first ever-identified supergene enrichment zone on Mars. The mineral paragenesis present at the site sets constrains on the characteristics of early Martian atmosphere. A chrysocolla/malachite bearing unit in the largest of Shalbatana Valley paleolacustrine sediment accumulation constitutes the proof for this process. The water permanence at the formation time is the main implication of this finding. Furthermore, the potential biogenic involvement at the mineralization stage adds scientific importance to the site. The latter implication could set the site as a high priority choice for future Martian in-situ robotic roving/sample-return missions. The relative age of the area (˜3.7 Ba) adds weight to this finding for purposes of planetary atmosphere evolution comparison. No Earth supergene deposit has survived that long, making this site extremely important to address the problem of the oxidative conditions of the primordial Earth and Mars atmospheres.

  11. 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

  12. 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.

  13. Drip Magmatism: Intra-Plate Volcanism and Its Importance to the Early Earth and Other Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Elkins-Tanton, L. T.

    2014-12-01

    In the present neither Mars nor Venus has Earth-like plate tectonics, though both are likely still volcanically active. Volcanism on Mars and Venus most resembles intra-plate volcanism on Earth, where magmatism occurs through intact lithospheric plates, away from plate boundaries. On Earth intra-plate magmatism has long been proposed to be the result of lithospheric thinning through delamination or ductile dripping. Exactly how these processes create volcanism, however, has remained obscure; particularly in the case of ductile dripping, which does not produce significant topography in the lithosphere-asthenosphere boundary. Though its fall may not trigger significant asthenospheric upwelling, the sinking drip itself will heat conductively as it enters the asthenosphere, and may itself melt, depending upon its solidus temperature and the temperature of the asthenosphere. We refer to this as "drip magmatism," following the hypothesis of Elkins-Tanton (2007). This model produces testable predictions for the resulting magmatic compositions. Drip magmatism was tested by Ducea (2013) for the Altiplano Plateau in the central Andes, by Holbig and Grove (2008) for magmas from Tibet, by Elkins-Tanton (2014) for the Sierra Nevada, and by Furman et al. (2014) for the central African rift; geochemistry in all these localities confirm drip magmatism. Drip magmatism provides a quantifiable mechanism for slow but regular recycling of volatiles into a planetary atmosphere. Further, it could be driven primarily by carbon, or halogens, or other incompatible and volatile elements, in addition to water. Thus, volcanism on one-plate planets, or during a putative "hot" or "slow" tectonics phase on the early Earth, may provide sufficient volatile recycling for habitability.

  14. Spectral Characteristic of Tholin Produced from Possible Early Earth Atmospheres and its Role in Antigreenhouse Effect on Early Earth

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Imanaka, H.; Wilhite, P.; McKay, C.; Bakes, E.; Cruikshank, D. P.; Arakawa, E. T.

    2003-01-01

    We have produced organic material simulating a methane photochemical haze in a CO2- rich atmosphere of the early Earth by irradiating gas mixtures in an inductively coupled cold plasma chamber with pressure approx. 0.25 mbar at 100 W total power. The flow rate was 24 cm3 min. We added progressively higher levels of CH, by combining gas mixtures of N2/CH4 (9/1) and N2/CO2 (9/1) to change the ratio of CH4/CO2. Tholin was accumulated for 5 hours in each experiment; the onset of tholin formation is in the range CH4/CO2 = 0.5 to 1. As the mixing ratio of CH, is increased, the production rate of the brownish tholin film increases. IR spectra showed the C-H and N-H bands similar to that of Titan tholin and closely resemble Titan tholin made at 0.13 mbar pressure. A decrease in the CH bonds on decreasing CH4/CO2 is noted. Ether bands (-(2-O-C) were tentatively detected, but no detectable carbonyl (C=O) band was found. The absorption in the UV region for the early Earth tholin is found to be substantially greater than the Titan tholin. Quantitative values of the optical constants of early Earth tholin are currently being measured.

  15. Atmosphere and water loss from early Mars under extreme solar wind and extreme ultraviolet conditions.

    PubMed

    Terada, Naoki; Kulikov, Yuri N; Lammer, Helmut; Lichtenegger, Herbert I M; Tanaka, Takashi; Shinagawa, Hiroyuki; Zhang, Tielong

    2009-01-01

    The upper limits of the ion pickup and cold ion outflow loss rates from the early martian atmosphere shortly after the Sun arrived at the Zero-Age-Main-Sequence (ZAMS) were investigated. We applied a comprehensive 3-D multi-species magnetohydrodynamic (MHD) model to an early martian CO(2)-rich atmosphere, which was assumed to have been exposed to a solar XUV [X-ray and extreme ultraviolet (EUV)] flux that was 100 times higher than today and a solar wind that was about 300 times denser. We also assumed the late onset of a planetary magnetic dynamo, so that Mars had no strong intrinsic magnetic field at that early period. We found that, due to such extreme solar wind-atmosphere interaction, a strong magnetic field of about approximately 4000 nT was induced in the entire dayside ionosphere, which could efficiently protect the upper atmosphere from sputtering loss. A planetary obstacle ( approximately ionopause) was formed at an altitude of about 1000 km above the surface due to the drag force and the mass loading by newly created ions in the highly extended upper atmosphere. We obtained an O(+) loss rate by the ion pickup process, which takes place above the ionopause, of about 1.5 x 10(28) ions/s during the first < or =150 million years, which is about 10(4) times greater than today and corresponds to a water loss equivalent to a global martian ocean with a depth of approximately 8 m. Consequently, even if the magnetic protection due to the expected early martian magnetic dynamo is neglected, ion pickup and sputtering were most likely not the dominant loss processes for the planet's initial atmosphere and water inventory. However, it appears that the cold ion outflow into the martian tail, due to the transfer of momentum from the solar wind to the ionospheric plasma, could have removed a global ocean with a depth of 10-70 m during the first < or =150 million years after the Sun arrived at the ZAMS. PMID:19216683

  16. A sensitivity study on the effects of particle chemistry, asphericity and size on the mass extinction efficiency of mineral dust in the terrestrial atmosphere: from the near to thermal IR

    Microsoft Academic Search

    R. A. Hansell; J. S. Reid; S. C. Tsay; T. L. Roush; O. V. Kalashnikova

    2010-01-01

    To determine a plausible range of mass extinction efficiencies (MEE) of terrestrial atmospheric dust from the near to thermal IR, sensitivity analyses are performed over an extended range of dust microphysical and chemistry perturbations. The IR values are subsequently compared to those in the near-IR, to evaluate spectral relationships in their optical properties. Synthesized size distributions consistent with measurements, model

  17. 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.

  18. Centennial to millennial variations of atmospheric methane during the early Holocene

    NASA Astrophysics Data System (ADS)

    Yang, Ji-Woong; Ahn, Jinho; Brook, Edward

    2015-04-01

    Atmospheric CH4 is one of the most important greenhouse gases. Ice core studies revealed strong correlations between millennial CH4 variations and Greenland climate during the last glacial period. However, millennial to sub-millennial CH4 variations during interglacial periods are not well studied. Recently, several high-resolution data sets have been produced for the late Holocene, but it is difficult to distinguish natural- from anthropogenic changes. In contrast, the methane budget of the early Holocene is not affected by anthropogenic disturbances, thus may help us better understand natural CH4 control mechanisms under interglacial climate boundary conditions. Here we present our new high-precision and high-resolution atmospheric CH4 record from Siple Dome ice core, Antarctica that covers the early Holocene. We used our new wet extraction system at Seoul National University that shows a good precision of ~1 ppb. Our data show several tens of ppb of centennial- to millennial CH4 variations and an anti-correlative evolution with Greenland climate on the millennial time scale. The CH4 record could have been affected by many different types of forcing, including temperature, precipitation (monsoon intensity), biomass burning, sea surface temperature, and solar activity. According to our data, early Holocene CH4 is well correlated with records of hematite stained grains (HSG) in North Atlantic sediment records, within age uncertainties. A red-noise spectral analysis yields peaks at frequencies of ~1270 and ~80 years, which are similar to solar frequencies, but further investigations are needed to determine major controlling factor of atmospheric CH4during the early Holocene.

  19. 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.

  20. Stability of the vegetation-atmosphere system in the early Eocene climate

    NASA Astrophysics Data System (ADS)

    Port, U.; Claussen, M.

    2015-05-01

    We explore the stability of the atmosphere-vegetation system in the warm, almost ice-free early Eocene climate and in the interglacial, pre-industrial climate by analysing the dependence of the system on the initial vegetation cover. The Earth system model of the Max Planck Institute for Meteorology is initialised with either dense forests or bare deserts on all continents. Starting with desert continents, an extended desert remains in Central Asia in early Eocene climate. Starting with dense forest coverage, this desert is much smaller because the initially dense vegetation cover enhances water recycling in Central Asia relative to the simulation with initial deserts. With a smaller Asian desert, the Asian monsoon is stronger than in the case with a larger desert. The stronger Asian monsoon shifts the global tropical circulation leading to coastal subtropical deserts in North and South America which are significantly larger than with a large Asian desert. This result indicates a global teleconnection of the vegetation cover in several regions. In present-day climate, a bi-stability of the atmosphere-vegetation system is found for Northern Africa only. A global teleconnection of bi-stabilities in several regions is absent highlighting that the stability of the vegetation-atmosphere system depends on climatic and tectonic boundary conditions.

  1. Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002) 19111931 www.elsevier.com/locate/jastp

    E-print Network

    Mendillo, Michael

    2002-01-01

    This paper presents results from the TIME-GCM-CCM3 thermosphere­ionosphere­lower atmosphere ux-coupled model for overemphasizing the daytime summer=winter anomaly in both hemispheres and seriously underestimating night NmF2 that both annual and semiannual variations of F2-layer electron density are largely caused by changes

  2. 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.

  3. 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.

  4. 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

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Carr, M. H.

    1989-06-01

    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.

  7. Early Validation Analyses of Atmospheric Profiles from EOS MLS on the Aura Satellite

    NASA Technical Reports Server (NTRS)

    Froidevaux, Lucien; Livesey, Nathaniel J.; Read, William G.; Jiang, Yibo B.; Jimenez, Carlos; Filipiak, Mark J.; Schwartz, Michael J.; Santee, Michelle L.; Pumphrey, Hugh C.; Jiang, Jonathan H.; Wu, Dong L.; Manney, Gloria L.; Drouin, Brian J.; Waters, Joe W.; Fetzer, Eric J.; Bernath, Peter F.; Boone, Chris D.; Walker, Kaley A.; Jucks, Kenneth W.; Geoffrey, C. Toon; Margitan, James J.; Sen, Bhaswar; Webster, Christopher R.; Christensen, Lance E.; Elkins, James W.

    2006-01-01

    We present results of early validation studies using retrieved atmospheric profiles from the Earth Observing System Microwave Limb Sounder (MLS) instrument on the Aura satellite. 'Global' results are presented for MLS measurements of atmospheric temperature, ozone, water vapor, hydrogen chloride, nitrous oxide, nitric acid, and carbon monoxide, with a focus on the January-March 2005 time period. These global comparisons are made using long-standing global satellites and meteorological datasets, as well as some measurements from more recently launched satellites. Comparisons of MLS data with measurements from the Ft. Sumner, NM, September 2004 balloon flights are also presented. Overall, good agreeement is obtained, often within 5% to 10%, but we point out certain issues to resolve and some larger systematic differences; some artifacts in the first publicly released MLS (version 1.5) dataset are noted.We comment briefly on future plans for validation and software improvements.

  8. The National Ecological Observatory Network's Atmospheric and Terrestrial Instrumentation: Data Quality Assurance/Control of First Release Data

    NASA Astrophysics Data System (ADS)

    Streett, S.; Roberti, J. A.; Smith, D.; Taylor, J. R.

    2013-12-01

    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 illustrate preliminary results of our quality assurance and quality control (QA/QC) program applied to NEON's first deployed site in Sterling, CO. These initial results demonstrate NEON's dynamic approach to building upon existing QA/QC frameworks in an effort to attain the highest levels of accuracy, precision, and operational time, while efficiently optimizing the effort needed to produce quality data products. Results will focus on quality control checks of Temperature, Barometric Pressure, and Photosynthetically Active Radiation.

  9. Global terrestrial carbon cycle

    SciTech Connect

    Smith, T.M.; Cramer, W.P.; Dixon, R.K.; Leemans, R.; Neilson, R.P.

    1993-01-01

    There is great uncertainty with regard to the future role of the terrestrial biosphere in the global carbon cycle. The uncertainty arises from both an inadequate understanding of current pools and fluxes as well as the potential effects of rising atmospheric concentrations of CO2 on natural ecosystems. Despite these limitations, a number of studies have estimated current and future patterns of terrestrial carbon storage. Future estimates focus on the effects of a climate change associated with a doubled atmospheric concentration of CO2. Available models for examining the dynamics of terrestrial carbon storage and the potential role of forest management and landuse practices on carbon conservation and sequestration are discussed. (Copyright (c) 1993 Kluwer Academic Publishers.)

  10. 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...

  11. Features of the ocean-atmosphere exchange in the North Atlantic and its effect on terrestrial climate conditions

    NASA Astrophysics Data System (ADS)

    Alexei, Kartushinsky

    The climatic changes on Earth are to a large extent influenced by the intensity of oceanatmosphere-land interactions. Energy exchange in the atmosphere-ocean system depends on the transfer of warm and cold water masses by stream flows. Interaction of water masses leads to formation of frontal zones with high temperature gradients. Such zones are easily detected by temperature gradients which are calculated according to AVHRR MCSST satellite data for the 1982 - 1986 (average monthly) and 1990 - 2001 (average weekly) periods. The spatial extension and the size of the frontal zone formed by Gulf Stream and Labrador Current in North Atlantic affects the evaporation mode. Such interaction with atmosphere leads to changes in the cyclonic and anticyclonic activity in the North Atlantic Oscillation (NAO) zone. In this work the seasonal North Atlantic Oscillations are compared with the SST gradients in North Atlantic for the period of satellite measurements. Besides, the investigation is made of the connection between the changes of NAO and climatic parameters overland. We used the weather stations data concerning the average monthly air temperature and precipitation for the territory of Eurasia for the period of 1900-2004. This work analyses the features of ocean-atmosphere interaction and the effect of such interaction on the climatic conditions. We developed software for the analysis of climagrams in graphic form, in which the air temperature and amount of precipitation are averaged over the whole observation period, and also for separate periods. The average seasonal and annual climagrams of several parts of land in latitudinal direction are compared with the seasonal and annual indices of NAO. Besides, comparison is made between the variability amplitudes of precipitation and air temperature over a prolonged observation period.

  12. Ideas and perspectives: on the emission of amines from terrestrial vegetation in the context of new atmospheric particle formation

    NASA Astrophysics Data System (ADS)

    Sintermann, J.; Neftel, A.

    2015-06-01

    In this article we summarise recent science which shows how airborne amines, specifically methylamines (MAs), play a key role in new atmospheric 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 NPF 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 was already 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. The decomposition of organic material constitutes another, potentially ubiquitous, source of 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.

  13. XUV exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets II: Hydrogen coronae and ion escape

    E-print Network

    Kislyakova, K G; Holmström, M; Panchenko, M; Odert, P; Erkaev, N V; Leitzinger, M; Khodachenko, M L; Kulikov, Yu N; Güdel, M; Hanslmeier, A

    2012-01-01

    The interactions between the stellar wind plasma flow of a typical M star such as GJ 436 and hydrogen-rich upper atmospheres of an Earth-like planet and a "super-Earth" with the radius of 2 R_Earth and a mass of 10 M_Earth, located within the habitable zone at ~0.24 AU are studied. The formation of extended atomic hydrogen coronae under the influence of such factors as 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 heating efficiency on the evolution of the hydrogen-rich upper atmospheres is investigated. XUV fluxes which are 1, 10, 50 and 100 times higher compared to that of the present Sun are considered and the formation of the high-energy neutral hydrogen clouds around the planets due to charge-exchange reaction under various stellar conditions have been modeled. Charge-exchange between stellar wind protons with the planetary hydrogen atoms and photoionization leads to the production of initially cold io...

  14. Effects of atmospheric heating on infalling meteorites and micrometeorites: Relevance to conditions on the early earth

    NASA Astrophysics Data System (ADS)

    Wright, I. P.; Yates, P. D.; Pillinger, C. T.

    Since micrometeorites may have played an important role in the development of conditions on the early Earth, bringing vital supplies of the biogenically important elements, it is apposite to appraise the effects that atmospheric heating exerts on such particles as they head towards the planet's surface. An expedient way to approach this problem is to undertake an investigation of the effects of pulse-heating on the carbon inventories of micrometeorites arriving at the present time. Unfortunately analytical techniques for carbon have not yet advanced to the point where levels of sensitivity are compatible with a study of this type. However, it is still possible to contemplate the effects of atmospheric heating by utilizing samples of relatively well documented meteorites as analogs of micrometeorites. To this end small samples of three meteorites (Allende, Weston and Goalpara) have been subjected to pulse-heating in order to investigate the effects of atmospheric infall on carbon chemistry. In this preliminary study the samples were heated in air thereby simulating present day atmospheric conditions. The results show, not surprisingly, that heating removes carbon. However, the extent of this effect is dependent upon combustion kinetics, which in turn is presumably related to the nature of individual components and their location within the samples. For instance, the results show that refractory carbon-bearing components are not only able to survive pulse-heating to 1500°C, but may actually become enriched in samples as a result of a heating episode (i.e., as a consequence of preferential removal of other more labile materials). Although carbon is removed by heating, this does not appear to affect the carbon isotopic composition of the material that remains. This means that analyses of micrometeorites falling to Earth at the present time, although recording artificially low carbon contents, will be to some extent valid in terms of carbon isotopic measurements (especially where stepped combustion is used to acquire the relevant data above a certain threshold temperature, which is itself related to the extent of atmospheric heating). Furthermore, a detailed calibration of the extent of carbon removal may assist the development of atmospheric heating models, thereby constraining entry velocities, and ultimately sources. To simulate effectively the nature of infall heating in former times, more sophisticated experiments would need to be carried out involving the use of synthetic atmospheres prepared from various gas mixtures.

  15. 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.

  16. 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.

  17. Reconciling estimates of the contemporary North American carbon balance among an inventory-based approach, terrestrial biosphere models, and atmospheric inversions

    NASA Astrophysics Data System (ADS)

    Hayes, D. J.; Turner, D. P.; Stinson, G.; McGuire, A. D.; Wei, Y.; West, T. O.; Heath, L. S.; De Jong, B. H.; McConkey, B. G.; Birdsey, R.; Kurz, W. A.; Jacobson, A. R.; Huntzinger, D. N.; Pan, Y.; Post, W. M.; Cook, R. B.

    2011-12-01

    Although the exact contribution is uncertain, North American (NA) ecosystems are thought to have a significant influence on the global carbon budget by acting as a large sink of atmospheric CO2 in recent decades. Assessments of the continental carbon balance have been based on various scaling approaches, including top-down atmospheric inverse models (AIMs) and bottom-up terrestrial biosphere models (TBMs), which vary widely in their estimates of the magnitude, timing and spatial pattern of sources and sinks of atmospheric CO2. A suite of results on NA ecosystem carbon flux from extant model simulations (based on both AIMs and TBMs) have been organized by the North American Carbon Program (NACP). Here, we assemble and analyze available inventory-based data on NA ecosystem carbon cycle components as an additional perspective alongside the NACP models. We develop an inventory-based approach for estimating net ecosystem exchange (NEE) over NA that notably retains information on the spatial distribution of the vertical fluxes as well as accounting for lateral transfers. The total inventory-based NEE estimate of a -327 ± 252 TgC yr-1 sink for NA was driven primarily by CO2 uptake in the Forest Lands (-248 TgC yr-1) and in the Crop Lands (-297 TgC yr-1) sectors. These sinks are counteracted by the CO2 source estimated for the Other Lands sector (+218 TgC yr-1), where much of the forest and crop products are returned to the atmosphere through consumption and decay. The ecosystems of Mexico are estimated to be a small net source (+18 TgC yr-1) due to land use change. We compare these inventory-based estimates with results from the TBMs and AIMs, where the mean continental-scale NEE estimate for each ensemble is -511 TgC yr-1 and -931 TgC yr-1, respectively. Additional fluxes not measured by the inventories, though 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. Depending on the approach, the estimates of the NA sink presented here represent between 18% and 52% of continental fossil fuel emissions over this same time period.

  18. 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

  19. Stratospheric balloon flight experiment campaign for the simulation of the Huygens probe mission: verification of HASI (Huygens Atmospheric Structure Instrument) performance in terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Lion Stoppato, P. F.; Ferri, F.; Bettanini, C.; Colombatti, G.; Antonello, M.; Bastianello, S.; Aboudan, A.; Flamini, E.; Gaborit, V.; Zarnecki, J. C.; Hathi, B.; Harri, A. M.; Lehto, A.; Bianchini, G.; Angrilli, F.; Fulchignomi, M.

    2004-02-01

    A stratospheric balloon flight experiment campaign is in progress, in collaboration with the Italian Space Agency (ASI), simulate the Huygens probe descent on Titan. The main purposes of this campaign of experiments are: - to verify sensors for planetary atmosphere entry probes effective performance in conditions similar to those of the actual mission descent - to obtain a set of data useful for the analysis of the probe trajectory as well as for the attitude reconstruction - to determine the atmospheric vertical profiles. A mock up of the Huygens probe carrying onboard HASI instrument and other Huygens instrumentation is launched with a stratospheric balloon from the ASI launch base of Trapani for a local flight on Sicily. The probe is lifted up to an altitude higher than 32 kilometres by means of a stratospheric balloon. Once the balloon is cut away, the probe starts to descent dragged by the parachute till the impact on ground. During the descent phase the probe spins at a rate inside the range of velocities expected for the mission thanks to straight line cascade and the de-coupling of the probe rotation from that one of the parachute. The measurements carried out during all the ascending and descending phases are transmitted in real time to ground by telemetry to check the system functionality and send telecommand, if needed. At the same time data are recorded and stored on board for post-flight processing. After landing the gondola and payload are recovered. Both the 2002 and 2003 flights have been extremely successful in terms of quantity and quality of acquired data, furthermore the equipment has been recovered working properly so that it will possible to re-use it in future flight.

  20. 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.

  1. Calculation of infrared limb emission by ozone in the terrestrial middle atmosphere. I - Source functions. II - Emission calculations

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Drayson, S. Roland

    1990-01-01

    The departure from LTE in the vibration-rotation bands of ozone in the middle atmosphere is analyzed using two statistical equilibrium models: the energy gap model and the simplified single model. The diurnal variations in the fundamental band source functions nu(1) and nu(3) is determined by the diurnal change in the rate of ozone photolysis by the solar radiation. Source functions are presented for the vibration-rotation bands of ozone that emit in the 9-11-micron spectral interval, over an altitude range of 1-110 km. Results are also reported of the evaluation of the radiative transfer equation incorporating these source functions and energy level populations. Using the results of the two statistical equilibrium models, calculations are carried out of the spectrally integrated limb radiance for the limb viewing geometry for daytime conditions. Results indicate that the interpretation of the measurements of spectrally integrated limb radiance from ozone will be greatly complicated by the breakdown of LTE in the vibration-rotational bands of ozone.

  2. Leaf fossil record suggests limited influence of atmospheric CO2 on terrestrial productivity prior to angiosperm evolution

    PubMed Central

    Boyce, C. Kevin; Zwieniecki, Maciej A.

    2012-01-01

    Declining CO2 over the Cretaceous has been suggested as an evolutionary driver of the high leaf vein densities (7–28 mm mm?2) that are unique to the angiosperms throughout all of Earth history. Photosynthetic modeling indicated the link between high vein density and productivity documented in the modern low-CO2 regime would be lost as CO2 concentrations increased but also implied that plants with very low vein densities (less than 3 mm mm?2) should experience substantial disadvantages with high CO2. Thus, the hypothesized relationship between CO2 and plant evolution can be tested through analysis of the concurrent histories of alternative lineages, because an extrinsic driver like atmospheric CO2 should affect all plants and not just the flowering plants. No such relationship is seen. Regardless of CO2 concentrations, low vein densities are equally common among nonangiosperms throughout history and common enough to include forest canopies and not just obligate shade species that will always be of limited productivity. Modeling results can be reconciled with the fossil record if maximum assimilation rates of nonflowering plants are capped well below those of flowering plants, capturing biochemical and physiological differences that would be consistent with extant plants but previously unrecognized in the fossil record. Although previous photosynthetic modeling suggested that productivity would double or triple with each Phanerozoic transition from low to high CO2, productivity changes are likely to have been limited before a substantial increase accompanying the evolution of flowering plants. PMID:22689947

  3. Regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl in a 188,000 km 2 area in the European arctic as displayed by terrestrial moss samples-long-range atmospheric transport vs local impact

    NASA Astrophysics Data System (ADS)

    Reimann, Clemens; De Caritat, Patrice; Halleraker, Jo H.; Finne, Tor Erik; Boyd, Rognvald; Jæger, Øystein; Volden, Tore; Kashulina, Galina; Bogatyrev, Igor; Chekushin, Viktor; Pavlov, Vladimir; Äyräs, Matti; Räisänen, Marja Liisa; Niskavaara, Heikki

    The regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl have been mapped in a 188,000 km2 area of the European Arctic (N Finland, N Norway, NW Russia) using the moss technique. The Russian nickel mining and smelting industry (Nikel and Zapoljarnij (Pechenganikel) and Monchegorsk (Severonikel)) in the eastern part of the survey area represents two of the largest point sources for S0 2 and metal emissions on a world wide basis. In contrast, parts of northern Finland and northern Norway represent still some of the most pristine areas in Europe. The terrestrial mosses Hylocomium splendens and Pleurozium schreberi were used as monitors of airborne deposition. Samples in all three countries were collected during the summer of 1995 and analysed in one laboratory using ICP-MS. Maps for most elements clearly show elevated element concentrations near the industrial sites and delineate the extent of contamination. Pollution follows the main wind and topographical directions in the area (N-S). The gradients of deposition are rather steep. Background levels for all the elements are reached within 150-200 km from the industrial plants. The relative importance of long-range atmospheric transport of air pollutants from industrial point sources on the world wide increase of heavy metals observed in the atmosphere is thus debatable for many elements. Increasing population and traffic density, accompanied by increasing local dust levels, may play a much more important role than industrial emissions. The regional distribution patterns as displayed in the maps show some striking differences between the elements. The regional distribution of Hg and TI in the survey area is completely dominated by sources other than industry.

  4. Quantifying the Net Exchanges of Carbon Dioxide and Methane between the Atmosphere and Terrestrial Biosphere in Northern High Latitudes

    NASA Astrophysics Data System (ADS)

    Zhuang, Qianlai

    2015-04-01

    Wetlands occupy vast areas in boreal regions (above 45oN) and play an important role in the regional exchanges of carbon dioxide (CO2) and methane (CH4) between land ecosystems and the atmosphere. We have developed a biogeochemistry model that considers the effects of thawing permafrost and complex hydrological dynamics on plant photosynthesis, plan nutrient uptake, and both aerobic and anaerobic decompositions of organic carbon of wetland ecosystems in this region. The process-based biogeochemistry model was applied to evaluate how spatial and temporal variations in both CO2 and CH4 have changed in the last century and will change during this century. Our current estimate of net CH4 emissions from this region is 67.8±6.2 Tg CH4 yr-1 during the period of 1993-2004. In contrast, we estimate that the region acts as a net carbon sink of -1.28±0.03 Pg C yr-1 with a persistent wetland carbon sink from -0.38 to -0.41 Pg C yr-1 and an upland sink from -0.6 to -1.1 Pg C yr-1. Our analysis indicates that wetlands play a disproportionally important role in affecting regional greenhouse gas budgets given that they only occupy a small fraction of the total land area in the region. In addition, this talk will present our model projections of both CO2 and CH4 dynamics in the region during the 21st century. More importantly, this talk will make recommendations on data collection and model improvement based on our decade-long modeling efforts in this region.

  5. 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

  6. 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.

  7. Use of stable isotopes in the study of CO2 fluxes between terrestrial vegetation and the atmosphere in shortgrass steppe

    NASA Astrophysics Data System (ADS)

    Shim, J. H.; Pendall, E.; Ojima, D. S.

    2001-12-01

    The shortgrass steppe ecosystem is ecologically sensitive to climate change due the mixture of C3 and C4 plant species and the semi-arid environment. In order to make reliable predictions about effects of climate change on plant communities, it is prerequisite to understand how individual C3 and C4 plant functional groups contribute gross photosynthetic activity and respiration in the semi-arid grassland. We observed diurnal and seasonal changes of CO2, CH4 and N2O fluxes, and associated isotopic signatures of 13C and 18O from air flasks above canopy at 1 and 2m heights, to estimate changes in activity of C3 andC4 plants and gross photosynthesis and respiration fluxes during the growing seasons of 2000 and 2001 in the shortgrass steppe region of north-eastern Colorado. Flasks were collected from a tower instrumented with Bowen ratio equipment, allowing us to evaluate latent heat fluxes simultaneously with flask measurements. We partitioned gross fluxes using the 13C and 18O isotopic mass balance method outlined by Yakir and Wang (1996). The results indicated that the grass canopy was a sink for CO2 during the daytime, as we expected, but peak times for CO2 uptake varied seasonally. Peak patterns of daily photosynthesis were attributed microclimatic variables such as leaf to air vapor pressure deficit related to stomatal conductance. The diurnal patterns of gradients for d13 C were similar to those for d18O. Discrimination against 13 C associated with CO2 fixation and isotopic exchange with 18O-enriched leaf water during daytime may be correlated process in this ecosystem. Seasonally, gross photosynthesis was positively correlated to magnitude of depleted d13C of CO2 from all sources, latent heat flux at night, and total greenness of plants. Seasonal changes in atmospheric d13C and d18O values, CO2 fluxes and gross photosynthesis reflected changes in plant biomass and its composition by functional groups (C3, C4 and CAM) and environmental variables especially related to hydrological cycling such as evapotranspiration. We compared local-scale (10 to 100 m) flask results with observations from chambers to assess fine-scale (0.1 to 1 m) differences in respiration and ä13C and ä18O values from selected species and bare ground.

  8. 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

  9. A methodology for estimating seasonal cycles of atmospheric CO2 resulting from terrestrial net ecosystem exchange (NEE) fluxes using the Transcom T3L2 pulse-response functions

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Baker, D. F.; Gurney, K. R.

    2012-09-01

    We present a method for translating modeled terrestrial net ecosystem exchange (NEE) fluxes of carbon into the corresponding seasonal cycles in atmospheric CO2. The method is based on the pulse-response functions from the Transcom 3 Level 2 (T3L2) atmospheric tracer transport model (ATM) intercomparison. The new pulse-response method is considerably faster than a full forward ATM simulation, allowing CO2 seasonal cycles to be computed in seconds, rather than the days or weeks required for a forward simulation. Further, the results provide an estimate of the range of transport uncertainty across 13 different ATMs associated with the translation of surface NEE fluxes into an atmospheric signal. We evaluate the method against the results of archived forward ATM simulations from T3L2. The latter are also used to estimate the uncertainties associated with oceanic and fossil fuel influences. We present a regional breakdown at selected monitoring sites of the contribution to the atmospheric CO2 cycle from the 11 different T3L2 land regions. A test case of the pulse-response code, forced by NEE fluxes from the Community Land Model, suggests that for many terrestrial models, discrepancies between model results and observed atmospheric CO2 cycles will be large enough to clearly transcend ATM uncertainties.

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

    E-print Network

    Satish Kumar; Manfred Cuntz; Zdzislaw E. Musielak

    2015-06-09

    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.

  11. 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.

  12. 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.

  13. 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). Dept. of Advanced Technology; Cazzoli, E.G.; Khatib-Rahbar, M. [Energy Research, Inc., Rockville, MD (United States)

    1995-12-31

    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.

  14. 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.

  15. Neoarchean paleoweathering of tonalite and metabasalt: Implications for reconstructions of 2.69Ga early terrestrial ecosystems and paleoatmospheric chemistry

    USGS Publications Warehouse

    Driese, S.G.; Jirsa, M.A.; Ren, M.; Brantley, S.L.; Sheldon, N.D.; Parker, D.; Schmitz, M.

    2011-01-01

    Field and laboratory investigations of a 2690.83Ma (207Pb/206Pb age of Saganaga Tonalite) unconformity exposed in outcrop in northeastern Minnesota, USA, reveal evidence for development of a deep paleoweathering profile with geochemical biosignatures consistent with the presence of microbial communities and weakly oxygenated conditions. Weathering profiles are characterized by a 5-50m thick regolith that consists of saprolitized Saganaga Tonalite and Paulson Lake succession basaltic metavolcanic rocks retaining rock structure, which is cross-cut by a major unconformity surface marking development of a successor basin infilled with alluvial deposits. The regolith and unconformity are overlain by thick conglomerate deposits that contain both intrabasinal (saprock) as well as extrabasinal detritus. Thin-section microscopy and electron microprobe analyses reveal extensive hydrolysis and sericitization of feldspars, exfoliation and chloritization of biotite, and weathering of Fe-Mg silicates and Cu-Fe sulfides; weathering of Fe-Ti oxides was relatively less intense than for other minerals and evidence was found for precipitation of Fe oxides. Geochemical analyses of the tonalite, assuming immobile TiO2 during weathering (??Ti,j), show depletion of SiO2, Al2O3, Na2O, CaO, MgO, and MnO, and to a lesser degree of K2O, relative to least-weathered parent materials. Significant Fe was lost from the tonalite. A paleoatmospheric pCO2 of 10-50 times PAL is estimated based on geochemical mass-balance of the tonalite profile and assuming a formation time of 50-500Kyr. Interpretations of metabasalt paleoweathering are complicated by additions of sediment to the profile and extensive diagenetic carbonate (dolomite) overprinting. Patterns of release of P and Fe and retention of Y and Cu in tonalite are consistent with recent laboratory experiments of granite weathering, and with the presence of acidic conditions in the presence of organic ligands (produced, for example, by a primitive microbial community) during weathering. Cu metal in the profile may document lower pO2 than present day at the surface. Comparison with previous studies of weathered tonalite and basalt (Denison, 2.45-2.22Ga) in Ontario, Canada, reveal general similarities in paleoweathering with our study, as well as important differences related to lower paleoatmospheric pO2 and terrestrial biosignature for the older Minnesota profile. A falling water table in the Alpine Lake locality is presumed to have promoted formation of this gossan-like deep-weathering system that extends to 50-m depth. ?? 2011 Elsevier B.V.

  16. 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.

  17. 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

  18. 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

  19. Terrestrial Exoplanet Light Curves

    E-print Network

    Eric Gaidos; Nicholas Moskovitz; Darren M. Williams

    2005-11-23

    The phase or orbital light curves of extrasolar terrestrial planets in reflected or emitted light will contain information about their atmospheres and surfaces complementary to data obtained by other techniques such as spectrosopy. We show calculated light curves at optical and thermal infrared wavelengths for a variety of Earth-like and Earth-unlike planets. We also show that large satellites of Earth-sized planets are detectable, but may cause aliasing effects if the lightcurve is insufficiently sampled.

  20. Terrestrial Gravity Fluctuations

    E-print Network

    Harms, Jan

    2015-01-01

    The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

  1. Terrestrial Gravity Fluctuations

    E-print Network

    Jan Harms

    2015-07-21

    The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

  2. Insights into the early Eocene hydrological cycle from an ensemble of atmosphere-ocean GCM simulations

    NASA Astrophysics Data System (ADS)

    Carmichael, Matthew; Lunt, Daniel; Pancost, Richard

    2015-04-01

    Recent studies utilising a range of geochemical proxies have indicated that a significant perturbation to global hydrology occurred at the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma). An enhanced hydrological cycle for the warm early Eocene is also suggested to have played a key role in maintaining high-latitude warmth during this interval. Comparisons of proxy data to General Circulation Model (GCM) simulated hydrology have not widely been made however, and inter-model variability remains poorly characterised despite significant differences in simulated surface temperatures. In this work, we address this by undertaking an intercomparison of GCM-derived precipitation distributions within the EoMIP ensemble (Lunt et al., 2012), which includes previously-published early Eocene simulations performed using five GCMs differing in boundary conditions, model structure and precipitation-relevant parameterisation schemes. We show that an intensified hydrological cycle is simulated for all Eocene simulations relative to preindustrial. This is primarily due to elevated atmospheric paleo-CO2, although the effects of differences in paleogeography/ice sheets are also of importance in some models. For a given CO2 level, globally-averaged precipitation rates vary widely between models, largely as a result of different climate sensitivities (dT/dCO2) and differing parameterisation schemes. Despite this, models with similar global precipitation sensitivities (dP/dT) display different regional responses for a given temperature change. Regions which are particularly model sensitive include the South Pacific, tropical Africa and the Tethys and may represent targets for future proxy acquisition. A comparison of leaf-fossil-derived precipitation estimates with GCM data illustrates that models tend to unanimously underestimate early Eocene precipitation rates at high latitudes. Models which warm these regions via elevated CO2 or by utilising alternative parameterisations are most successful in simulating a match with geologic data. Further data from low-latitude regions and better constraints on early Eocene CO2 are required to discriminate between these model simulations, given the large error bars on paleoprecipitation estimates. Given the clear differences apparent between simulated precipitation distributions within the ensemble, further interrogation of paleohydrological data may offer an independent means by which to evaluate model skill for warm climates.

  3. 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).

  4. 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 ...

  5. 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.

  6. Depositional styles of Early Ediacaran terrestrial volcanosedimentary succession in Gebel El Urf area, North Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Eliwa, Hassan; Breitkreuz, Christoph; Khalaf, Ibrahim; Gameel, Khaled El

    2010-06-01

    Located 100 km northwest of Hurghada, the volcanosedimentary successions of Gebel El Urf is exposed between latitude 27° 45' 30? and 27° 51' 00? N and longitude 32° 49' 00? and 32° 59' 00? E. The volcanosedimentary successions of Gebel El Urf crop out in an area dominated by different Late Proterozoic plutonic complexes. Both, erosional and intrusive contacts with different granitoid units have been identified. Two SHRIMP ages have been obtained from crystal-rich and lithic-poor ignimbrites yielding 615 ± 4 and 616.0 ± 5.4 Ma placing the evolution of the inter-montane basins, described here, into the Early Ediacaran. In the Gebel El Urf area, a southeastward dipping succession (Gebel El Urf Succession, GUS) of ca. 2000 m thickness rests on coarse-grained granite with an erosional unconformity. Another succession present in the area (Wadi Kefri Succession, WKS) represents volcanogenic sediments which exhibit degrees of metamorphic overprint. In places, it is presumed to be older than GUS. For the GUS, 14 lithofacies types have been differentiated and grouped to seven lithofacies associations. Subdivided into four depositional phases, GUS starts with a thick, massive and clast-supported conglomerate of alluvial fan facies (well-rounded clasts up to 100 cm). GUS continues with pelitic to sandy-turbiditic lacustrine and sandy braided river deposits with occasional volcanic glassy fragments (now illite) (Phase 2). The upper half of the GUS is dominated by volcanic deposits, starting with a 50 m thick package of alternating ignimbrites and synvolcanic sedimentary mass flow deposits, the latter related to phreatomagmatic vents (Phase 3). A thick succession of welded to non-welded ignimbrites follows, with one 20 m intercalation of coarse well-rounded conglomerates (Phase 4). Numerous SiO 2-rich and - poor dykes and sills emplaced into GUS. The GUS development displays a cycle from high to low energy sedimentation and back, under humid climatic conditions. Phase 2 was characterized by extension and down faulting of basin shoulders. Tectonic activity presumably also led to damming of the river creating a sweat water lake. Volcanism commenced with small vents during Phase 2 and terminated with voluminous eruptions in Phase 4.

  7. 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.

  8. Linked magma ocean solidification, cumulate mantle compositions, and atmospheric growth

    Microsoft Academic Search

    L. Elkins-Tanton; E. Parmentier

    2007-01-01

    Early in terrestrial planet evolution energetic impact, radiodecay, and core formation may have created one or more whole or partial silicate mantle magma oceans. The time to mantle solidification and then to clement surface conditions allowing liquid water is highly dependent upon heat flux from the planetary surface through a growing primitive atmosphere. Here we model the time to clement

  9. 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.

  10. 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.

  11. Terrestrial Laser Scanning

    Microsoft Academic Search

    Mathias Lemmens

    \\u000a Since the early 2000s terrestrial laser scanning has evolved from a research and development (R&D) topic to a geo-data technology,\\u000a which is commercially offered by a multitude of land surveying companies and other service providers all over the world. The\\u000a technology is primarily used for the rapid acquisition of three-dimensional (3D) information of a variety of topographic and\\u000a industrial objects.

  12. TERRESTRIAL ECOTOXICOLOGY

    EPA Science Inventory

    Terrestrial ecotoxicology is the study of how environmental pollutants affect land-dependent organisms and their environment. It requires three elements: (1) a source, (2) a receptor, and (3) an exposure pathway. This article reviews the basic principles of each of each element...

  13. 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.

  14. Terrestrial planet formation.

    PubMed

    Righter, K; O'Brien, D P

    2011-11-29

    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 (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) 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

  15. 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

  16. 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, D. J.; Turner, D. P.; Stinson, Graham; McGuire, A. David; Wei, Yaxing; West, Tristram O.; Heath, L.; deJong, B.; McConkey, Brian; Birdsey, Richard A.; Kurz, Werner; Jacobson, Andy; Huntzinger, Deborah N.; Pan, Y.; Post, W. M.; Cook, R. B.

    2012-04-02

    While fossil fuel emissions are calculated with relatively high precision, understanding the fate of those emissions with respect to sequestration in terrestrial ecosystems requires data and methods that can reduce uncertainties in the diagnosis of land-based CO2 sinks. The wide range in the land surface flux estimates is related to a number of factors, but most generally because of the different methodologies used to develop estimates of carbon stocks and flux, and the uncertainties inherent in each approach. The alternative approaches to estimating continental scale carbon fluxes that we explored here can be broadly classified as applying a top-down or bottom-up perspective. Top-down approaches calculate land-atmosphere carbon fluxes based on atmospheric budgets and inverse modeling. Bottom-up approaches rely primarily on measurements of carbon stock changes (the inventory approach) or on spatially distributed simulations of carbon stocks and/or fluxes using process-based modeling (the forward modelapproach).

  17. Formation of early water oceans on rocky planets

    Microsoft Academic Search

    Linda T. Elkins-Tanton

    2011-01-01

    Terrestrial planets, with silicate mantles and metallic cores, are likely to obtain water and carbon compounds during accretion. Here I examine the conditions that allow early formation of a surface water ocean (simultaneous with cooling to clement surface conditions), and the timeline of degassing the planetary interior into the atmosphere. The greatest fraction of a planet's initial volatile budget is

  18. Venus: A search for clues to early biological possibilities

    NASA Technical Reports Server (NTRS)

    Colin, Larry; Kasting, James F.

    1992-01-01

    The extensive evidence that there is no extant life on Venus is summarized. The current atmospheric environment, which is far too hostile by terrestrial standards to support life, is described. However, exobiologists are interested in the possibility of extinct life on Venus. The early history of Venus is discussed in terms of its ability to sustain life that may now be extinct.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Early Calibration Results from the Atmospheric Infrared Sounder (AIRS) on Aqua

    Microsoft Academic Search

    Thomas S. Pagano; Hartmut H. Aumann; Steven L. Gaiser; David T. Gregorich

    The Atmospheric Infrared Sounder (AIRS) is a space-based hyperspectral infrared instrument designed to measure Earth's atmospheric water vapor and temperature profiles on a global scale. AIRS has 2378 infrared channels in the spectral range of 3.7 - 15.4 microns with a spatial resolution of 13.5 km and 4 Vis\\/\\

  4. Early Validation of Vertical Profiles from the Envisat Atmospheric Instruments GOMOS and MIPAS with the University of Bonn Lidar at the Esrange in July and August 2002 (AOID222)

    Microsoft Academic Search

    K. H. Fricke; U. Blum

    2003-01-01

    The vertical structure of the terrestrial atmosphere is governed by hydrostatic equilibrium, which relates altitude, temper- ature, and pressure (or density). The mixing ratios derived for the chemically important trace gases depend on a precise knowledge of this basic atmospheric structure. The Bonn University backscatter lidar on the Esrange (68N, 21E) near Kiruna, Sweden, was operated from mid-July to the

  5. Initiative to quantify terrestrial carbon sources and sinks

    Microsoft Academic Search

    Josef Cihlar; Scott Denning; Frank Ahem; Olivier Arino; Alan Belward; Francis Bretherton; Wolfgang Cramer; Gerard Dedieu; Christopher Field; Roger Francey; Rene Gommes; James Gosz; Kathy Hibbard; Tamotsu Igarashi; Pavel Kabat; Dick Olson; Stephen Plummer; Ichtiaque Rasool; Michael Raupach; Robert Scholes; John Townshend; Riccardo Valentini; Diane Wickland

    2002-01-01

    Questions related to the distribution and spatio-temporal dynamics of the terrestrial carbon fluxes are at the core of current scientific and policy debates. In recent years, the primary concern has been the increasing CO2 content in the atmosphere, its effect on climate, and the associated role of terrestrial ecosystems in mitigating the increase and impact of climate change. However, terrestrial

  6. The Fate of Water in the Martian Magma Ocean and the Formation of an Early Atmosphere

    Microsoft Academic Search

    L. T. Elkins-Tanton; E. M. Parmentier

    2005-01-01

    A chondritic martian magma ocean degasses during solidification to create an initial water atmosphere consistent with the planet's current water content, while the mantle retains sufficient water to reduce viscosity and encourage convection.

  7. 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.

  8. Using observational data to evaluate global terrestrial

    E-print Network

    Atmosphere Coupled Land Models Coupled carbon-climate models disagree on the continued strength of the net to model land-atmosphere carbon exchange #12;Terrestrial Biospheric Models Well-informed Carbon cycle effective carbon management strategies Model evaluation and assessment North American Carbon Program Interim

  9. Possible climates on terrestrial exoplanets

    E-print Network

    Forget, Francois

    2013-01-01

    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 first order, climate primarily depends on 1) The atmospheric composition and the volatile inventory; 2) The incident stellar flux; 3) 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 volatile, atmospheric escape, geochemistry, photochemistry. 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 sim...

  10. Solar Wind Interaction with the Martian Upper Atmosphere at Early Mars/Extreme Solar Conditions

    NASA Astrophysics Data System (ADS)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.

    2014-12-01

    The investigation of ion escape fluxes from Mars, resulting from the solar wind interaction with its upper atmosphere/ionosphere, is important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~ 300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model output fields into the 3-D BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid MHD model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres. This feature allows us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model output fields are used as the input for the multi-fluid MHD model and the M-GITM is used as input into the AMPS exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD calculations (1-way coupled) for 2.5 GYA conditions and/or extreme solar conditions for present day Mars (high solar wind velocities, high solar wind dynamic pressure, and high solar irradiance conditions, etc.). Present day extreme conditions may result in MF-MHD outputs that are similar to 2.5 GYA cases. The crustal field orientations are also considered in this study. By comparing estimates of past ion escape rates with the current ion loss rates to be returned by the MAVEN spacecraft (2013-2016), we can better constrain the total ion loss to space over Mars history, and thus enhance the science returned from the MAVEN mission.

  11. Ontong Java volcanism initiated long-term climate warming that caused substantial changes in terrestrial vegetation several tens of thousand years before the onset of OAE1a (Early Aptian, Cretaceous)

    NASA Astrophysics Data System (ADS)

    Keller, Christina E.; Hochuli, Peter A.; Giorgioni, Martino; Garcia, Therese I.; Bernasconi, Stefano M.; Weissert, Helmut

    2010-05-01

    During Cretaceous times, several intense volcanic episodes are proposed as trigger for episodic climate warming, for changes in marine circulation patterns and for elevated marine productivity, which resulted in the widespread black shale deposits of the Oceanic Anoxic Events (OAE). In the sediments underlying the early Aptian OAE1a black shales, a prominent negative carbon isotope excursion is recorded. Its origin had long been controversial (e.g. Arthur, 2000; Jahren et al., 2001) before recent studies attributed it to the Ontong Java volcanism (Méhay et al., 2009; Tejada et al., 2009). Volcanic outgassing results in an increased pCO2 and should lead to a rise in global temperatures. We therefore investigated if the volcanically-induced increase in pCO2 at the onset of OAE1a in the early Aptian led to a temperature rise that was sufficient to affect terrestrial vegetation assemblages. In order to analyse changes in terrestrial palynomorph assemblages, we examined 15 samples from 12 black shale horizons throughout the early Aptian negative C-isotope spike interval of the Pusiano section (Maiolica Formation; N-Italy). These sediments were deposited at the southern continental margin of the alpine Tethys Ocean and have been bio- and magnetostratigraphically dated by Channell et al. (1995). In order to obtain a continuous palynological record of the negative C-isotope spike interval and the base of OAE1a, we combined this pre-OAE1a interval of Pusiano with the OAE1a interval of the nearby Cismon section (Hochuli et al., 1999). The sporomorph assemblages at the base of this composite succession feature abundant bisaccate pollen, which reflects a warm-temperate climate. Rather arid conditions are inferred from low trilete spore percentages. Several tens of thousand years before the onset of OAE1a, C-isotope values started to decrease. Some thousand years later, bisaccate pollen began to decrease, whereas an increase of Classopollis spp. and Araucariacites spp. percentages indicate a rise in temperatures. Maximum temperatures (suggested by a dominance of Classopollis spp.) were only reached after the most negative inorganic C-isotope values and after the onset of OAE1a. Our study shows that the volcanically-induced increase in pCO2, which ultimately led to OAE1a caused a substantial climate warming that seriously affected terrestrial vegetation. References: Arthur, M.A., 2000, Volcanic contributions to the carbon and sulfur geochemical cycles and global change, in Sigurdsson, H., Houghton, B., McNutt, S.R., Rymer, H., and Stix, J., eds., Encyclopedia of Volcanoes, Academic Press, p. 1045-1056. Channell, J.E.T., Cecca, F., and Erba, E., 1995, Correlations of Hauterivian and Barremian (Early Cretaceous) stage boundaries to polarity chrons: Earth and Planetary Science Letters, v. 134, p. 125-140. Hochuli, P.A., Menegatti, A.P., Weissert, H., Riva, A., Erba, E., and Silva, I.P., 1999, Episodes of high productivity and cooling in the early Aptian Alpine Tethys: Geology, v. 27, p. 657-660. Jahren, A.H., Arens, N.C., Sarmiento, G., Guerrero, J., and Amundson, R., 2001, Terrestrial record of methane hydrate dissociation in the Early Cretaceous: Geology, v. 29, p. 159-162. Méhay, S., Keller, C.E., Bernasconi, S.M., Weissert, H., Erba, E., Bottini, C., and Hochuli, P.A., 2009, A volcanic CO2 pulse triggered the Cretaceous Oceanic Anoxic Event 1a and a biocalcification crisis: Geology, v. 37, p. 819-822. Tejada, M.L.G., Suzuki, K., Junichiro, K., Rodolfo, C., J., M.J., Naohiko, O., Tatsuhiko, S., and Yoshiyuki, T., 2009, Ontong Java Plateau eruption as a trigger for the early Aptian oceanic anoxic event: Geology, v. 37, p. 855-858.

  12. 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.

  13. Statistical equilibrium calculations for silicon in early-type model stellar atmospheres

    Microsoft Academic Search

    L. W. Kamp

    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

  14. Sources of atmospheric CH{sub 4} in early postglacial time

    SciTech Connect

    Nisbet, E.G. [Univ. of Saskatchewan, Saskatoon (Canada)

    1992-08-20

    This paper looks the the dramatic changes in methane levels in the atmosphere following the end of the last glacial period, and during the Oldest and Younger Dryas. Levels are inferred from measurements made on ice core samples. The rate of changes required to account for the dramatic increase seems unlikely to be explainable based on biologic sources. The author argues that releases from fossil sources may have been a major contributor to the dramatic shifts recorded in the ice core records.

  15. 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.

  16. Carbon Sequestration in Terrestrial Ecosystems

    NASA Astrophysics Data System (ADS)

    Jacobs, G. K.; Post, W. M.; Jastrow, J. D.; Izaurralde, R. C.

    2002-05-01

    CSiTE, the Department of Energy's research consortium performs fundamental research in support of new methods to enhance carbon sequestration in terrestrial ecosystems in an environmentally acceptable manner. The goal of CSiTE is to discover and characterize links between critical pathways and mechanisms across scales from the molecular to the landscape for creating larger, longer-lasting carbon pools in terrestrial ecosystems. This paper will present results relevant to increasing the biophysical potential of terrestrial C sequestration, but in addition will illustrate the importance of an integrative analysis in assessing this technological option (as well as all sequestration options). Our integrative approach involves six steps: (1) Identify promising technologies, (2) Understand controls on basic mechanisms at the site scale, (3) Perform sensitivity analyses over the range of applicable conditions (model, lab or field experiments), (4) Full C and greenhouse gas accounting, (5) Environmental impacts, and (6) Economic analysis including rate of adoption and cost tradeoffs. Many estimates of the potential contributions of sequestration by terrestrial ecosystems to the control of rising atmospheric carbon dioxide concentration have been rather modest. Indeed, there are many uncertainties and ancillary issues (permanence, land availability, water supply, etc) that must be considered. However, terrestrial ecosystems have not been viewed to-date as a "technology" to be implemented. Rather, the emphasis has been on the promotion of practices that are likely to be implemented for other benefits. It may be possible to use the attributes of terrestrial ecosystems to a greater extent in sequestering carbon. In this paper, we will discuss how a technology view of terrestrial ecosystems may alter the estimated contributions. Examples to be addressed include changing land use, shifting agricultural methods, manipulating soil properties, and altering soil microbial systems.

  17. Carbon dioxide on the early earth.

    PubMed

    Walker, J C

    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 the earth during the course of earth accretion or very shortly thereafter. This early degassing was a consequence of rapid accretion,which gave the young earth a hot and rapidly convecting interior. Second, the early earth lacked extensive, stable continental platforms on which carbon could be stored in the form of carbonate minerals for geologically significant periods of time. In the absence of continental platforms on the early earth, the earth's carbon must have been either in the atmosphere or ocean or in the form of shortlived sedimentary deposits on ephemeral sea floor. PMID:11542014

  18. 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.

  19. 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

  20. 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.

  1. 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.

  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. 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.

  4. Measurements of the CO_2 15 ?m Band System Broadened by Air, N_2 and CO_2 at Terrestrial Atmospheric Temperatures

    NASA Astrophysics Data System (ADS)

    Smith, M. A. H.; Devi, V. Malathy; Benner, D. Chris; Blake, T. A.; Sams, R. L.

    2009-06-01

    In earth remote sensing, retrievals of atmospheric temperature profiles are often based on observed radiances in infrared spectral regions where emission from atmospheric CO_2 predominates. To achieve improved retrieval accuracy, systematic errors in the forward model must be reduced, especially those associated with errors in the spectroscopic line calculation. We have recorded more than 110 new high-resolution infrared spectra of the 15-?m band system of CO_2 to accurately determine line intensities, self-, air- and N_2-broadened widths and pressure-induced line shifts, along with their temperature dependences. The spectra were recorded with the Bruker IFS 120 HR Fourier transform spectrometer at Pacific Northwest National Laboratory (PNNL) and temperature-controlled sample cells. Sample temperatures were between 206K and 298K. Maximum total pressures were 15 Torr for self-broadening and 613 Torr for air- and N_2-broadening. Analysis is done using a multispectrum fitting technique to retrieve the spectroscopic parameters. Line mixing and other non-Lorentz, non-Voigt line shapes are also assessed. The resulting line parameters are compared with the HITRAN database and with other measurements. D. Chris Benner, C.P. Rinsland, V. Malathy Devi, M.A.H. Smith, and D. Atkins, J. Quant. Spectrosc. Radiat. Transfer 53, 705-721 (1995) L.S. Rothman et al., J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005) L.S. Rothman et al., J. Quant. Spectrosc. Radiat. Transfer, in press (2009)

  5. Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse.

    PubMed

    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

    2010-08-24

    Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO(2) (8 to 22x 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 degrees -70 degrees S to approximately 40 degrees 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 pCO(2) from a modeled Sandbian level of approximately 8x PAL to approximately 5x 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

  6. The Valanginian terrestrial carbon-isotope record

    NASA Astrophysics Data System (ADS)

    Grocke, D. R.; Price, G. D.; Baraboshkin, E.; Mutterlose, J.; Ruffell, A. H.

    2003-04-01

    A stratigraphic, biostratigraphic and isotopic investigation has been performed on a Crimean section located on the Kacha River, Verkhorechie Village, SW Crimea. This clastic-dominated succession consists of a series of bioturbated inter-bedded shallow-marine silty sands, claystones and some oolitic sands. A published detailed study of the ammonite fauna has been undertaken and has revealed that the succession can be compared to standard Tethyan schemes. The lower part of the succession is dated on the basis of the ammonite fauna as Early Valanginian (otopeta-campylotoxus ammonite Zones), although this latter zone is highly condensed. A more expanded Late Valanginian is present (verrucosum, callidiscus and tauricum ammonite Zones), and is overlain by sand-dominated sediments of Early Hauterivian age. Throughout this section woody plant matter ranging in preservation from charcoal to coal has been collected and analyzed for stable carbon-isotope ratios. There is no correlation between state of preservation and carbon-isotope ratios. Carbon-isotope ratios range in the Early Valanginian from -24 ppm to -22 ppm, and in the mid-verrucosum Zone values shift abruptly towards more positive values and peak at -18 ppm in the lower callidiscus Zone. Wood carbon-isotope ratios decrease gradually through the remainder of the callidiscus Zone and return to pre-excursion values in the tauricum Zone. The remaining Hauterivian values fluctuate between -24 ppm to -21 ppm. The structure, magnitude and timing of the terrestrial carbon-isotope curve is very similar to the marine carbonate curve (from +1 ppm to +3 ppm) for the Valanginian. This would indicate, based on a delta-delta relationship between organic matter and carbonate, that there was very little change in atmospheric CO_2 concentrations during the Valanginian, and that the isotopic composition of the global carbon reservoir shifted. Future research on an Early Cretaceous (Valanginian-Hauterivian) interval from the Yatria River, sub-polar Urals, Western Siberia, which contains both belemnites and terrestrial wood fragments will provide another section from which to determine whether the delta-delta relationship for the Valanginian from Crimea is a global phenomenon or that it can be explained via latitudinal variation.

  7. Evaporative Control on Soil Water Isotope Ratios: Implications for Atmosphere-Land Surface Water Fluxes and Interpretation of Terrestrial Proxy Records

    NASA Astrophysics Data System (ADS)

    Kaushik, A.; Noone, D. C.; Berkelhammer, M. B.; O'Neill, M.

    2014-12-01

    The moisture balance of the continental boundary layer plays an important role in regulating the exchange of water and energy between the land surface and atmosphere. Near-surface moisture balance is controlled by a number of factors including precipitation, infiltration and evapotranspiration. Measurements of stable isotope ratios in water can be exploited to better understand the mechanisms controlling atmosphere-land surface water fluxes. Understanding the processes that set sub-surface water isotope ratios can prove useful for refining paleoclimate interpretations of stable oxygen and hydrogen isotope-based proxies. We present in situ tower-based measurements of stable isotope ratios of water (?D and ?18O) in vapor, precipitation and soil from the Boulder Atmospheric Observatory, a semi-arid tall-tower site in Erie, Colorado, from July 2012 to September 2014. Near surface profiles from 0 to 10 m were measured approximately every ninety minutes. Soil profiles from 0 to 30 cm, the region of maximum variability, were sampled on a weekly basis and cryogenically extracted for stable water isotope measurement. Evaporation-proof bulk rain collectors provided precipitation samples at this site. Results show disequilibrium exists between surface vapor and soil water isotopes, with the top 10 cm of soil water approaching equilibrium with the surface vapor right after a rain event because of high infiltration and saturation at the surface. At this semi-arid site with little vegetation, evaporative exchange is the main driver for soil water fluxes as the soil dries, corroborated by soil Dexcess profiles showing progressive enrichment through evaporation. In addition, when nighttime surface temperatures are cooler than deep soil, as is the case in many arid and semi-arid environments, upward vapor diffusion from the soil leads to dew formation at the surface which then contributes to surface vapor values. We use these observations to constrain a Craig-Gordon evaporation model at the land surface to weight the contributions of rainfall, surface water vapor exchange and sub-surface vapor diffusion to soil water isotope values. This has implications both for modeling short-term gas exchange at the land surface as well as for estimating past evaporative conditions from proxies like cave deposits and tree cellulose.

  8. Regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl in a 188,000 km 2 area in the European arctic as displayed by terrestrial moss samples-long-range atmospheric transport vs local impact

    Microsoft Academic Search

    Clemens Reimann; Patrice De Caritat; Jo H. Halleraker; Tor Erik Finne; Rognvald Boyd; Øystein Jæger; Tore Volden; Galina Kashulina; Igor Bogatyrev; Viktor Chekushin; Vladimir Pavlov; Matti Äyräs; Marja Liisa Räisänen; Heikki Niskavaara

    1997-01-01

    The regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl have been mapped in a 188,000 km2 area of the European Arctic (N Finland, N Norway, NW Russia) using the moss technique. The Russian nickel mining and smelting industry (Nikel and Zapoljarnij (Pechenganikel) and Monchegorsk (Severonikel)) in the eastern part of the survey area represents

  9. A Spherical Non-LTE Line-Blanketed Stellar Atmosphere Model of the Early B Giant epsilon CMa

    E-print Network

    J. P. Aufdenberg; P. H. Hauschildt; S. N. Shore; E. Baron

    1998-02-03

    We use a spherical non-LTE fully line blanketed model atmosphere to fit the full multi-wavelength spectrum, including the extreme ultraviolet (EUV) continuum observed by the {\\it Extreme Ultraviolet Explorer}, of the B2 II star \\epscma. The available spectrophotometry of \\epscma\\ from 350 \\AA\\ to 25 \\micron\\ is best fit with model parameters \\Teff = 21750\\,K, \\Logg = 3.5, and an angular diameter of 0.77 mas. The close agreement between the model and the measured EUV flux from \\epscma\\ is a result of the higher temperatures at the formation depths of the \\ion{H}{1} and \\ion{He}{1} Lyman continua compared to other models. The realistic model treatment of early B giants with spherical geometry and NLTE metal line blanketing results in the prediction of significantly larger EUV fluxes compared with plane-parallel models. We find that our metal line blanketed spherical models show significantly warmer temperature structures, 1-3 kK at the formation depth of the Lyman continua, and predict stronger EUV fluxes, up to a factor of 5 in the \\ion{H}{1} Lyman continuum, compared with plane-parallel atmospheres that have identical model parameters. In contrast, we find spherical and plane-parallel models that do not include metal line blanketing are nearly identical. Our \\Teff = 21000 K, \\Logg = 3.2, spherical NLTE model predicts more than twice as many hydrogen ionizing photons and over 200 times more neutral helium ionizing photons than a standard hydrostatic plane-parallel LTE model with the same stellar parameters.

  10. Terrestrial Ecosystem Adaptation

    E-print Network

    Mills, L. Scott

    Terrestrial Ecosystem Adaptation Steven W. Running and L. Scott Mills RFF REPORT ............................... 16 Expected Future Ecosystem Trends ................................................................................................................................................................ 27 #12; RUNNING AND MILLS 1 Terrestrial Ecosystem Adaptation Steven W. Running and L. Scott

  11. A Spherical Non-LTE Line-blanketed Stellar Atmosphere Model of the Early B Giant {epsilon} Canis Majoris

    SciTech Connect

    Aufdenberg, J.P. [Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85271-1504 (United States)] [Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85271-1504 (United States); Hauschildt, P.H. [Department of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, Georgia 30602-2451 (United States)] [Department of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, Georgia 30602-2451 (United States); Shore, S.N. [Department of Physics and Astronomy, Indiana University South Bend, South Bend, Indiana 46634-7111 (United States)] [Department of Physics and Astronomy, Indiana University South Bend, South Bend, Indiana 46634-7111 (United States); Baron, E. [Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019-0225 (United States)] [Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019-0225 (United States)

    1998-05-01

    We use a spherical non-LTE fully line-blanketed model atmosphere to fit the full multiwavelength spectrum, including the extreme-ultraviolet (EUV) continuum observed by the {ital Extreme} {ital Ultraviolet} {ital Explorer}, of the B2 II star {epsilon} Canis Majoris (CMa). The available spectrophotometry of {epsilon} CMa from 350 {Angstrom} to 25 {mu}m is best fitted with model parameters {ital T}{sub eff} = 21,750 K, log {ital g} = 3.5, and an angular diameter of 0.77 mas. Our best-fit model predicts a hydrogen ionizing flux, {ital q}{sub 0}, of 1.59 {times} 10{sup 21} photons cm{sup {minus}2} s{sup {minus}1} at the star`s surface and 2290 photons cm{sup {minus}2} s{sup {minus}1} at the surface of the Local Cloud. The close agreement between the model and the measured EUV flux from {epsilon} CMa is a result of the higher temperatures at the formation depths of the H i and He i Lyman continua compared with other models. The realistic model treatment of early B giants with spherical geometry and non-LTE metal line{endash}blanketing results in the prediction of significantly larger EUV fluxes compared with plane-parallel models. We find that our metal line{endash}blanketed spherical models show significantly warmer temperature structures, 1{endash}3 kK at the formation depth of the Lyman continua, and predict stronger EUV fluxes, up to a factor of 5 in the H i Lyman continuum, compared with plane-parallel atmospheres that have identical model parameters. In contrast, we find that spherical and plane-parallel models that do not include metal line blanketing are nearly identical. Our {ital T}{sub eff} = 21,000 K, log {ital g} = 3.2, spherical non-LTE model predicts more than twice as many hydrogen ionizing photons and over 200 times more neutral helium ionizing photons than a standard hydrostatic plane-parallel LTE model with the same stellar parameters. Our synthetic spectra are in reasonably good agreement with observed continuum and line fluxes from echelle spectra obtained with the Goddard High Resolution Spectrograph. While we find agreement between the absolute UV flux of {epsilon} CMa as measured by GHRS and our model atmosphere, these fluxes are {approximately}30{percent} higher in the UV than those measured by {ital IUE}, {ital OAO} {ital 2}, and {ital TD}-{ital 1}, in excess of the published errors in the absolute calibration of these data. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}

  12. Spaceborne microwave remote sensing of seasonal freeze-thaw processes in the terrestrial high latitudes: relationships with land-atmosphere CO2 exchange

    NASA Astrophysics Data System (ADS)

    McDonald, Kyle C.; Kimball, John S.; Zhao, Maosheng; Njoku, Eni; Zimmermann, Reiner; Running, Steven W.

    2004-12-01

    Landscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These realtively 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, spearately 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 Americ 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, through both appear to be effective surrogates for monitoring annual growing seasons at high latitudes.

  13. 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.

  14. 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.

  15. Numerical modeling of impact erosion of atmospheres: Preliminary results

    NASA Technical Reports Server (NTRS)

    Vickery, A. M.

    1993-01-01

    It is clear from the great diversity of atmospheres among the terrestrial planets that their formation and evolution must have depended on a balance among a number of different processes. One of these processes is atmospheric erosion by impacts, which may have been particularly effective on Mars. The reason is that geomorphic evidence on Mars suggests that this planet had, early in its history, dense enough atmosphere to sustain active precipitation over geologically significant periods of time. Analytic calculations indicate that neither the projectile entering the atmosphere nor the main crater ejecta can cause the lose of significant amounts of atmosphere. The vapor plume that is formed, however, expands rapidly as its internal energy is converted into kinetic energy, and may blow off the overlying atmosphere. A model of this part of the impact/atmosphere interaction predicts Mars could have lost a substantial early atmosphere by impact erosion alone. Although our more detailed calculations, which took into account the anisotropy of the atmosphere with respect to zenith angle, show that the process isn't quite as effective, they still indicate the probability of substantial atmospheric loss from Mars. The first results from 2-D hydrocode runs are discussed. These include two runs which make most of the same simplifying approximations as the analytic models, in order to compare the analytic and numerical results directly, and one run (as yet incomplete) that models the full impact.

  16. Formation of early water oceans on rocky planets

    Microsoft Academic Search

    Linda T. Elkins-Tanton

    2011-01-01

    Terrestrial planets, with silicate mantles and metallic cores, are likely to obtain water and carbon compounds during accretion.\\u000a Here I examine the conditions that allow early formation of a surface water ocean (simultaneous with cooling to clement surface\\u000a conditions), and the timeline of degassing the planetary interior into the atmosphere. The greatest fraction of a planet’s\\u000a initial volatile budget is

  17. Carbon dioxide exchange and early old-field succession

    Microsoft Academic Search

    Ryan E. Emanuel; John D. Albertson; Howard E. Epstein; Christopher A. Williams

    2006-01-01

    Old-field succession is a widespread process active in shaping landscapes in the eastern United States, contributing significantly to the terrestrial sink of atmospheric carbon dioxide, particularly at midlatitudes. However, few studies document ecosystem-scale carbon dioxide exchange during the early years of old-field succession, particularly during the temporal transition from cultivation to abandonment. Rates of carbon dioxide exchange were measured for

  18. 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

  19. Future changes in global terrestrial carbon cycle under RCP scenarios

    NASA Astrophysics Data System (ADS)

    Lee, C.; Boo, K. O.; Hong, J.; Seong, H.; Heo, T. K.; Seol, K. H.; La, N.; Shim, S.; Lee, J. H.

    2014-12-01

    Terrestrial ecosystem plays the important role as carbon sink in the global carbon cycle. Understanding of interactions of terrestrial carbon cycle with climate is important for better prediction of future climate change. In this study, terrestrial carbon cycle is investigated by Hadley Centre Global Environmental Model, version 2, Carbon Cycle (HadGEM2-CC) that considers vegetation dynamics and an interactive carbon cycle with climate. The simulation for future projection is based on the three (8.5 / 4.5 / 2.6) representative concentration pathways (RCPs) from 2006 to 2100 and compared with historical land carbon uptake from 1979 to 2005. Projected changes in ecological features such as production, respiration, net ecosystem exchange and climate condition show similar pattern in three RCPs, while the response amplitude in each RCPs are different. For all RCP scenarios, temperature and precipitation increase with rising of the atmospheric CO2. Such climate conditions are favorable for vegetation growth and extension, causing future increase of terrestrial carbon uptakes in all RCPs. At the end of 21st century, the global average of gross and net primary productions and respiration increase in all RCPs and terrestrial ecosystem remains as carbon sink. This enhancement of land CO2uptake is attributed by the vegetated area expansion, increasing LAI (Leaf Area Index), and early onset of growing season. After mid-21st century, temperature rising leads to excessive increase of soil respiration than net primary production and thus the terrestrial carbon uptake begins to fall since that time. Regionally the NEE (Net Ecosystem Exchange) average value of East-Asia (90°E-140°E, 20°N-60°N) area is bigger than that of the same latitude band. In the end-21st the NEE mean values in East-Asia area are -2.09 PgC yr-1, -1.12 PgC yr-1, -0.47 PgC yr-1 and zonal mean NEEs of the same latitude region are -1.12 PgC yr-1, -0.55 PgC yr-1, -0.17 PgC yr-1 for RCP 8.5, 4.5, 2.6 . Acknowledgements. This study is supported by the National Institute of Meteorological Research, Korea Meteorological Administration (NIMR-2012-B-2).

  20. High resolution long range terrestrial imaging

    Microsoft Academic Search

    Dan Slater

    2005-01-01

    Achieving high resolution imagery of distant terrestrial objects from ground based sensors presents a unique technical challenge. The entire optical path is fully immersed in a dense and turbulent atmosphere, resulting in a significant loss of scene contrast and resolution. Although there are strong similarities to the problems of high resolution astronomical and space object imaging, there are also some

  1. 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.

  2. Nitrogen isotopic components in the early solar system

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1994-01-01

    It is quite common to take the terrestrial atmospheric value of (15)N/(14)N (0.00366) as typical of nitrogen in the early solar system, but in fact there is little reason to suppose that this value had a nebula-wide significance. Indeed, it is not clear that there was a unique solar-system-wide (15)N/(14)N ratio, of whatever value. Here we review what is known about the distribution of the nitrogen isotopes among those solar-system objects that have been sampled so far and conclude that those isotopes reveal widespread inhomogeneity in the early solar system. Whether the isotopically distinct primordial components implied by this analysis were solid or gaseous or a mixture of both is not known. The isotopic composition of N in the Earth's mantle is controversial: estimates range from a 1.1 percent depletion in (15)N to a 1.4 percent enrichment. (Isotopic compositions will be expressed throughout as percent deviations from the terrestrial atmospheric value.) The present-day Martian atmosphere is characterized by a value of plus 62 percent but this enrichment in (15)N is attributed to selective loss of (14)N from the Martian exosphere. Modelling of this fractionation leads to an estimated primordial composition similar to the terrestrial atmospheric value, through the precision of this model-dependent result is unclear.

  3. Groundwater and Terrestrial Water Storage

    NASA Technical Reports Server (NTRS)

    Rodell, Matthew; Chambers, Don P.; Famiglietti, James S.

    2014-01-01

    Terrestrial water storage (TWS) comprises groundwater, soil moisture, surface water, snow,and ice. Groundwater typically varies more slowly than the other TWS components because itis not in direct contact with the atmosphere, but often it has a larger range of variability onmultiannual timescales (Rodell and Famiglietti, 2001; Alley et al., 2002). In situ groundwaterdata are only archived and made available by a few countries. However, monthly TWSvariations observed by the Gravity Recovery and Climate Experiment (GRACE; Tapley et al.,2004) satellite mission, which launched in 2002, are a reasonable proxy for unconfinedgroundwater at climatic scales.

  4. Atmosphere Mitigation in Precise Point Positioning Ambiguity Resolution for Earthquake Early Warning in the Western U.S.

    NASA Astrophysics Data System (ADS)

    Geng, J.; Bock, Y.; Reuveni, Y.

    2014-12-01

    Earthquake early warning (EEW) is a time-critical system and typically relies on seismic instruments in the area around the source to detect P waves (or S waves) and rapidly issue alerts. Thanks to the rapid development of real-time Global Navigation Satellite Systems (GNSS), a good number of sensors have been deployed in seismic zones, such as the western U.S. where over 600 GPS stations are collecting 1-Hz high-rate data along the Cascadia subduction zone, San Francisco Bay area, San Andreas fault, etc. GNSS sensors complement the seismic sensors by recording the static offsets while seismic data provide highly-precise higher frequency motions. An optimal combination of GNSS and accelerometer data (seismogeodesy) has advantages compared to GNSS-only or seismic-only methods and provides seismic velocity and displacement waveforms that are precise enough to detect P wave arrivals, in particular in the near source region. Robust real-time GNSS and seismogeodetic analysis is challenging because it requires a period of initialization and continuous phase ambiguity resolution. One of the limiting factors is unmodeled atmospheric effects, both of tropospheric and ionospheric origin. One mitigation approach is to introduce atmospheric corrections into precise point positioning with ambiguity resolution (PPP-AR) of clients/stations within the monitored regions. NOAA generates hourly predictions of zenith troposphere delays at an accuracy of a few centimeters, and 15-minute slant ionospheric delays of a few TECU (Total Electron Content Unit) accuracy from both geodetic and meteorological data collected at hundreds of stations across the U.S. The Scripps Orbit and Permanent Array Center (SOPAC) is experimenting with a regional ionosphere grid using a few hundred stations in southern California, and the International GNSS Service (IGS) routinely estimates a Global Ionosphere Map using over 100 GNSS stations. With these troposphere and ionosphere data as additional observations, we can shorten the initialization period and improve the ambiguity resolution efficiency of PPP-AR. We demonstrate this with data collected by a cluster of Real-Time Earthquake Analysis for Disaster mItigation (READI) network stations in southern California operated by UNAVCO/PBO and SOPAC.

  5. Thermal evolution of an early magma ocean in interaction with the atmosphere: conditions for the condensation of a

    E-print Network

    Brandeis, Geneviève

    , Earth and Venus. This time would be virtually infinite for an Earth-sized planet located at less than 0 modeling approach applied to the three terrestrial planets Mars, Earth and Venus if a water ocean ever conducted a parametric study and described the influences of some important parameters such as the Sun-planet

  6. A sensitivity study on the effects of particle chemistry, asphericity and size on the mass extinction efficiency of mineral dust in the terrestrial atmosphere: from the near to thermal IR

    NASA Astrophysics Data System (ADS)

    Hansell, R. A.; Reid, J. S.; Tsay, S. C.; Roush, T. L.; Kalashnikova, O. V.

    2010-07-01

    To determine a plausible range of mass extinction efficiencies (MEE) of terrestrial atmospheric dust from the near to thermal IR, sensitivity analyses are performed over an extended range of dust microphysical and chemistry perturbations. The IR values are subsequently compared to those in the near-IR, to evaluate spectral relationships in their optical properties. Synthesized size distributions consistent with measurements, model particle size, while composition is defined by the refractive indices of minerals routinely observed in dust, including the widely used OPAC/Hess parameterization. Single-scattering properties of representative dust particle shapes are calculated using the T-matrix, discrete dipole approximation and Lorenz-Mie light-scattering codes. For the parameterizations examined, MEE ranges from 0-1.2 m2 g-1, with large contributions from non-spheres composed of quartz and gypsum. At near-IR wavelengths, MEE for non-spheres generally exceeds those for spheres, while in the IR, shape-induced changes in MEE strongly depend on volume median diameter (VMD) and wavelength, particularly for MEE evaluated at the mineral resonant frequencies. MEE distributions appear to follow particle geometry and are evidence for shape dependency in the optical properties. It is also shown that non-spheres best reproduce the positions of prominent absorption peaks found in silicates. Generally, angular particles exhibit wider and more symmetric MEE distribution patterns from 8-10 ?m than those with smooth surfaces, likely due to their edge-effects. Lastly, MEE ratios allow for inferring dust optical properties across the visible-IR spectrum. We conclude MEE are significant for the parameter space investigated, and are a key component for applications including sea surface temperature retrievals and the study of direct aerosol radiative effects.

  7. 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

  8. 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.

  9. Clouds in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    West, R.

    1999-01-01

    In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice cyrstals suspended in the air. The study of clouds touches on many facets of armospheric science. The chemistry of clouds is tied to the chemistry of the surrounding atmosphere.

  10. Space and Terrestrial Photovoltaics: Synergy and Diversity

    Microsoft Academic Search

    Sheila G. Bailey; Ryne Raffaelle; Keith Emery

    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

  11. Comparison of synoptic climatological features of the atmospheric fields in the "wintertime pressure pattern" around the Japan Islands in early winter with those in midwinter

    NASA Astrophysics Data System (ADS)

    Kato, Kuranoshin; Tomooka, Nozomi; Nishimura, Nanako; Haga, Yuichi

    2015-04-01

    In midwinter, the intense cold air outbreak frequently occurs under the so-called "wintertime pressure pattern", resulting in the huge supply of the sensible (SH) and latent (LH) heats from the Japan Sea and the heavy snowfall events in the Japan Sea side of the Japan Islands. On the other hand, the "wintertime pressure pattern" also appears frequently from November to early December (in "early winter"), although the air temperature around the Japan Islands is still rather higher than in midwinter. Kato et al. (EGU2014-3651) examined the atmospheric situations in association with the relatively large precipitation around the Japan Sea side of the Japan Islands in the "wintertime pressure pattern" even in early winter. They reported the extremely huge amount of LH and SH from the Japan Sea as in midwinter at those events, under the outbreak of the very cold Siberia air mass at least in the mature stage of that pattern. However, since the seasonal cycle of the climate system in East Asia shows the many stages with rapid transitions influenced by the Asian monsoon, the 3-dimensional structures and the atmospheric processes in the "wintertime pressure pattern" would be of rather different character between early winter and midwinter. Thus the present study performed synoptic climatological analyses on the above features in early winter by comparing with those in midwinter based on the daily weather maps by JMA, NCEP/NCAR re-analysis data, and so on, for the 1971/72 to 2009/10winter. Statistical analyses for 1971/72 to 2009/10winter revealed that, although the "wintertime pressure pattern" in early winter had rather shorter persistency than that in midwinter, the eastward surface pressure gradient around the Japan Sea area (around 40N) (corresponding to the geostrophic northerly wind component) in that pressure pattern in early winter sometimes attained the equivalent magnitude to that in midwinter. Furthermore, the increase in the appearance frequency of that pressure pattern in midwinter from that in early winter was reflected by the increase in that with the longer persistency. According to the case study for 1983/84 winter, even in the strong "wintertime pressure pattern" situations, the Siberian High began to extend to the southwestern part of the Japan Islands (around 33N) just like a part of the "moving anticyclone" as the baroclinic instability wave along that latitude in early winter. Besides, the zonal extension of the cold area intruding southward in the lower layer at those events was generally narrower than in midwinter. Further comparison of the features in the "wintertime pressure pattern" between early winter and midwinter will be also discussed in the presentation.

  12. Monte Carlo simulation of the terrestrial hydrogen exosphere

    NASA Technical Reports Server (NTRS)

    Hodges, R. Richard, Jr.

    1994-01-01

    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.

  13. How Mars lost its atmosphere

    NASA Astrophysics Data System (ADS)

    Zahnle, Kevin

    There is a widespread suspicion that Mars thin atmosphere is in some way attributable to the planet's size. Another possibility is that the atmosphere was never degassed or outgassed in the first place. I prefer escape. Hydrodynamic escape (vigorous thermal escape) and impact erosion (expulsion of atmosphere by impacts) are two processes that should have been operative early. Although in principle hydrodynamic escape could have shrunk Mars atmosphere a hundredfold while leaving the composition of the remnant atmosphere nearly unaltered, very high escape fluxes are required. The implicated escape mechanism must have been efficient, nearly non-fractionating, and vastly more potent for Mars than for Earth or Venus. Impact erosion is an appealing candidate. Noble gases are the obvious first test. Noble gases are the most volatile elements and so are the most likely to have been affected by impact erosion and the easiest to address quantitatively. Xenon in particular imposes three constraints on how Mars lost its atmosphere: (1) the very low abundance of nonradiogenic Xe abundance of nonradiogenic Xe compared to Earth, Venus, and likely meteoritic sources; (2) its nonradiogenic isotopes distinct from likely meteoritic sources; and (3) the relatively high absolute abundance of radiogenic daughter of the extinct radionuclide I-129 (half-life 17 Myr). In impact erosion, the first two become constraints on the composition, mass distribution, and orbital elements of the impactors. The third requires that Mars lost its nonradiogenic Xe early, probably before it was 100 Myr old. Impact erosion can explain Mars by any of three stories. (1) Mars in unlikely. In a sort of planetary brinkmanship, impact erosion almost removed the entire atmosphere but was arrested just in time. (2) Martian noble gases are cometary and cometary Xe is as isotopically mass fractionated as Martian and terrestrial Xe. This is most easily accomplished if a relatively thick geochemically controlled CO2 atmosphere protected trace atmophiles against escape. (3) Mars was indeed stripped of its early atmosphere but a small remnant was safely stored in the regolith, later released as a byproduct of water mobilization.

  14. Unraveling the chemical space of terrestrial and meteoritic organic matter

    NASA Astrophysics Data System (ADS)

    Schmitt-Kopplin, Philippe; Harir, Mourad; Hertkorn, Norbert; Kanawati, Basem; Ruf, Alexander; Quirico, Eric; Bonal, Lydie; Beck, Pierre; Gabelica, Zelimir

    2015-04-01

    In terrestrial environments natural organic matter (NOM) occurs in soils, freshwater and marine environments, in the atmosphere and represents an exceedingly complex mixture of organic compounds that collectively exhibits a nearly continuous range of properties (size-reactivity continuum). In these materials, the "classical" biogeosignatures of the (biogenic and geogenic) precursor molecules, like lipids, lignins, proteins and natural products have been attenuated, often beyond recognition, during a succession of biotic and abiotic (e.g. photo- and redox chemistry) reactions. Because of this loss of biochemical signature, these materials can be designated non-repetitive complex systems. The access to extra-terrestrial organic matter is given i.e. in the analysis of meteoritic materials. Numerous descriptions of organic molecules present in organic chondrites have improved our understanding of the early interstellar chemistry that operated at or just before the birth of our solar system. However, many molecular analyses are so far targeted toward selected classes of compounds with a particular emphasis on biologically active components in the context of prebiotic chemistry. Here we demonstrate that a non-targeted ultrahigh-resolution molecular analysis of the solvent-accessible organic fraction of meteorite extracted under mild conditions allows one to extend its indigenous chemical diversity to tens of thousands of different molecular compositions and likely millions of diverse structures. The description of the molecular complexity provides hints on heteroatoms chronological assembly, shock and thermal events and revealed recently new classes of thousands of novel organic, organometallic compounds uniquely found in extra-terrestrial materials and never described in terrestrial systems. This high polymolecularity suggests that the extraterrestrial chemodiversity is high compared to terrestrial relevant biological and biogeochemical-driven chemical space. (ultra)High resolution analytical approaches will be presented in their application to unravel the chemical nature and organic signatures in bio-geosystems and especially in selected chondritic (organic and ordinary) and achondritic meteorites. We will focus on thermal effects in CM types of materials and describe the effect of shock events on the changes in chemodiversity and the formation of unique novel organic compounds using high magnetic field ultrahigh resolution mass spectrometry (12 Tesla ion cyclotron resonance Fourier transform mass spectrometry - ICR-FT/MS) and nuclear magnetic resonance spectroscopy (Cryo 800MHz NMR).

  15. Dynamic responses of terrestrial ecosystem carbon cycling to global climate change

    Microsoft Academic Search

    Mingkui Cao; F. Ian Woodward

    1998-01-01

    Terrestrial ecosystems and the climate system are closely coupled, particularly by cycling of carbon between vegetation, soils and the atmosphere. It has been suggested, that changes in climate and in atmospheric carbon dioxide concentrations have modified the carbon cycle so as to render terrestrial ecosystems as substantial carbon sinks,; but direct evidence for this is very limited,. Changes in ecosystem

  16. How uncertainties in future climate change predictions translate into future terrestrial carbon fluxes

    Microsoft Academic Search

    MARIE B ERTHELOT; PIERRE F RIEDLINGSTEIN; JEAN-LOUIS D UFRESNEw; PAT R I C K M O N F R AY

    2005-01-01

    We forced a global terrestrial carbon cycle model by climate fields of 14 ocean and atmosphere general circulation models (OAGCMs) to simulate the response of terrestrial carbon pools and fluxes to climate change over the next century. These models participated in the second phase of the Coupled Model Intercomparison Project (CMIP2), where a 1% per year increase of atmospheric CO2

  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. 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 the Sun, rotation affects erosion Crater density can indicate surface age Earth has a unique geology: ­ P-waves: compressional waves ­ S-waves: shear waves S-waves cannot pass through liquid ­ Earth

  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. 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

  1. 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.

  2. 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.

  3. Predictability of the Barents Sea ice in early winter: Remote effects of oceanic and atmospheric thermal conditions from the North Atlantic

    NASA Astrophysics Data System (ADS)

    Nakanowatari, Takuya; Sato, Kazutoshi; Inoue, Jun

    2015-04-01

    Predictability of sea ice concentrations (SICs) in the Barents Sea in early winter (November-December) is studied using canonical correlation analysis with atmospheric and ocean anomalies from the NCEP Climate Forecast System Reanalysis (NCEP-CFSR) data. We find that the highest prediction skill for a single-predictor model is obtained from the 13-month lead subsurface temperature at 200-m depth (T200) and the in-phase meridional surface wind (Vsfc). T200 skillfully predicts SIC variability in 35% of the Barents Sea, mainly in the eastern side. The T200 for negative sea-ice anomalies exhibits warm anomalies in the subsurface ocean temperature downstream of the Norwegian Atlantic Slope Current (NwASC) on a decadal timescale. The diagnostic analysis of NCEP-CFSR data suggests that the subsurface temperature anomaly stored below the thermocline during summer re-emerges in late autumn by atmospheric cooling and affects the sea-ice. The subsurface temperature anomaly of the NwASC is advected from the North Atlantic subpolar gyre over about 3 years. Vsfc skillfully predicts SIC variability in 32% of the Barents Sea, mainly in the western side. The Vsfc for the negative sea-ice anomalies exhibits southerly wind anomalies. Vsfc is related to the large-scale atmospheric circulation patterns from the subtropical North Atlantic to the Eurasian continent. Our study suggests that both atmospheric and oceanic remote effects have a potential impact on the forecasting accuracy of SIC.

  4. Formation of Early Water Oceans on Rocky Planets

    E-print Network

    Elkins-Tanton, Linda T

    2010-01-01

    Terrestrial planets, with silicate mantles and metallic cores, are likely to obtain water and carbon compounds during accretion. Here I examine the conditions that allow early formation of a surface water ocean (simultaneous with cooling to clement surface conditions), and the timeline of degassing the planetary interior into the atmosphere. The greatest fraction of a planet's initial volatile budget is degassed into the atmosphere during the end of magma ocean solidification, leaving only a small fraction of the original volatiles to be released into the atmosphere through later volcanism. Rocky planets that accrete with water in their bulk mantle have two mechanisms for producing an early water ocean: First, if they accrete with at least 1 to 3 mass% of water in their bulk composition, liquid water may be extruded onto the planetary surface at the end of magma ocean solidification. Second, at initial water contents as low as 0.01 mass% or lower, during solidification a massive supercritical fluid and steam ...

  5. Atmosphere-Ice-Ocean Interactions During Early Autumn Freeze-up: Boundary-Layer and Surface Observations from the ACSE Field Program

    NASA Astrophysics Data System (ADS)

    Persson, Ola; Brooks, Barbara; Tjernström, Michael; Sedlar, Joseph; Brooks, Ian; Shupe, Matthew; Björck, Göran; Prytherch, John; Salisbury, Dominic; Achtert, Peggy; Sotiropoulou, Georgia; Johnston, Paul; Wolfe, Daniel

    2015-04-01

    Surface energy fluxes are key to the annual summer melt and autumn freeze-up of Arctic sea ice, but are strongly modulated by atmospheric, ocean, and sea-ice processes. This paper will examine direct observations of energy fluxes during the onset of autumn freeze-up from the Arctic Clouds in Summer Experiment (ACSE), and place them in context of those from other observational campaigns. The ACSE field program obtained measurements of surface energy fluxes, boundary-layer structure, cloud macro- and microphysical structure, and upper-ocean thermal and salinity structure from pack-ice and open-water regions in the eastern Arctic from early July to early October 2014. Late August and September measurements showed periods of energy flux deficits, leading to freeze-up of sea ice and the ocean surface. The surface albedo and processes impacting the energy content of the upper ocean appear key to producing a temporal difference between the freeze-up of the sea ice and adjacent open water. While synoptic conditions, atmospheric advection, and the annual solar cycle have primary influence determining when energy fluxes are conducive for melt or freeze, mesoscale atmospheric phenomena unique to the ice edge region appear to also play a role. For instance, low-level jets were often observed near the ice edge during the latter part of ACSE, and may have enhanced the turbulent energy loss. In conjunction with observations of summer melt, these observations of the onset of freeze-up suggest scenarios of key atmospheric processes, including thermal advection on various scales, that are important for the annual evolution of melt and freeze-up.

  6. Effect of increasing CO2 on the terrestrial carbon cycle

    PubMed Central

    Schimel, David; Fisher, Joshua B.

    2015-01-01

    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

  7. 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

  8. The Early Origins of Terrestrial C4

    E-print Network

    : glyceraldehydes-3- phosphate INTRODUCTION The photosynthetic process of converting carbon dioxide and water reserved 0084-6597/07/0530-0435$20.00 Key Words paleoclimate, carbon isotopes, bioapatite, paleosols a critical CO2 threshold was breached 30 Ma, that potentially selected for CO2-concentrating mechanisms

  9. Limiting future atmospheric carbon dioxide

    NASA Astrophysics Data System (ADS)

    Sarmiento, Jorge L.; Le QuéRé, Corinne; Pacala, Stephen W.

    1995-03-01

    We estimate anthropogenic carbon emissions required to stabilize future atmospheric CO2 at various levels ranging from 350 ppm to 750 ppm. Over the next three centuries, uptake by the ocean and terrestrial biosphere would permit emissions to be 3 to 6 times greater than the total atmospheric increase, with each of them contributing approximately equal amounts. Owing to the nonlinear dependence of oceanic and terrestrial biospheric uptake on CO2 concentration, the uptake by these two sinks decreases substantially at higher atmospheric CO2 levels. The uptake also decreases with increased atmospheric CO2 growth rate. All the stabilization scenarios require a substantial future reduction in emissions.

  10. Global change and terrestrial hydrology - A review

    NASA Technical Reports Server (NTRS)

    Dickinson, Robert E.

    1991-01-01

    This paper reviews the role of terrestrial hydrology in determining the coupling between the surface and atmosphere. Present experience with interactive numerical simulation is discussed and approaches to the inclusion of land hydrology in global climate models ae considered. At present, a wide range of answers as to expected changes in surface hydrology is given by nominally similar models. Studies of the effects of tropical deforestation and global warming illustrate this point.

  11. 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.

  12. 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.

  13. Extra Terrestrial Lava Flows

    NASA Technical Reports Server (NTRS)

    Lopes-Gautier, R.

    1993-01-01

    Volcanism has been one of the major processes shaping the surfaces of the terrestrial planets. Lava flows have been identified on the Moon, Mars, Venus, and on Juptier's moon Io. The study of extra-terrestrial lavas has largely relied on the interpretation of remotely acquired imaging, topographic and spectroscopic data. Models relating the final flow morpohology to eruption characteristics and magma chemistry have been important tools in the interpretation of these data.

  14. Stability of Earth-Like N2 Atmospheres: Implications for Habitability

    NASA Astrophysics Data System (ADS)

    Lammer, Helmut; Kislyakova, Kristina G.; Güdel, Manuel; Holmström, Mats; Erkaev, Nikolai V.; Odert, Petra; Khodachenko, Maxim L.

    According to recent studies related to the EUV heating by the young Sun of Earth's nitrogen atmosphere, upper atmosphere temperatures could rise up to several thousand Kelvin. For fluxes larger ? 7 times that of today's Sun the thermosphere changes from a hydrostatic to a dynamically expanding non-hydrostatic regime, adiabatically cools but expands beyond the magnetopause so that the magnetosphere is not able to protect the upper atmosphere from solar wind erosion. A N2-rich terrestrial atmosphere would have been lost within a few million years during the EUV active period of the young Sun ? 4 Ga ago. These results indicate that a hydrogen-rich gaseous envelope, which could have remained from Earths protoatmosphere and/or higher atmospheric CO2 amounts may have protected Earth's atmospheric nitrogen inventory against efficient escape to space. An alternative scenario would be that the nitrogen in Earth's early atmosphere was degassed or delivered during the late heavy bombardment period, where the solar EUV flux decreased to values < 7 times of the modern value. Finally, we discuss how EUV heated and extended upper atmospheres and their interaction with the host star's plasma environment could be observed around transiting Earth-like exoplanets at dwarf stars by space observatories such as the WSO-UV. Such future observations could be used to test the discussed atmospheric evolution scenarios and would enhance our understanding on the impact on the activity of the young Sun/star on the early atmospheres of Venus, Earth, Mars and exoplanets.

  15. 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.

  16. 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

  17. 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

  18. Terrestrial Carbon Cycle Dynamics under Recent and Future Climate Change

    Microsoft Academic Search

    H. Damon Matthews; Andrew J. Weaver; Katrin J. Meissner

    2005-01-01

    The behavior of the terrestrial carbon cycle under historical and future climate change is examined using the University of Victoria Earth System Climate Model, now coupled to a dynamic terrestrial vegetation and global carbon cycle model. When forced by historical emissions of CO2 from fossil fuels and land-use change, the coupled climate-carbon cycle model accurately reproduces historical atmospheric CO2 trends,

  19. Terrestrial FeO Continuum Emission Observed in Sky Spectra

    NASA Astrophysics Data System (ADS)

    Slanger, Tom G.; Melchiorri, R.; Saran, D. V.

    2011-01-01

    The terrestrial continuum emission in the visible spectral region has often been studied by both astronomers and aeronomers, in order to clarify backgrounds and the nature of the emissions. New observations from the ESI spectrograph on the Keck II telescope, as well as from the OSIRIS/Odin spectrograph and orbiter, have established that a major component of the emission originates with the FeO molecule [Evans et al., 2010]. This quasi-continuum peaks at 5950 A and extends from 5000 A well into the infrared. The identity has been demonstrated by comparison with meteor trains and laboratory measurements [Jenniskens et al., 2000]. Early studies of the continuum show consistency with the FeO emission as presently observed [Gadsden and Marovich, 1973]. Analysis of spectra from Kitt Peak [Neugent and Massey, 2010] demonstrates the great similarity between FeO emission in a clean atmosphere and high pressure sodium lamp emission in a polluted atmosphere. This research was supported by NSF Aeronomy under Grant ATM-0637433 . Evans, W.F.J., et al., Geophys. Res. Lett. [in press, 2010] Gadsden, M. and E. Marovich, J. Atm. Terr. Phys., 35, 1601-1614 [1973] Jenniskens, P., et al., Earth, Moon and Planets, 82-83, 429-434 [2000] Neugent, K.F. and P. Massey, PASP [in press, 2010

  20. Thermal evolutions of the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Toksoz, M. N.; Hsui, A. T.; Johnston, D. H.

    1978-01-01

    Theoretical models are formulated for the thermal evolution of the moon, Mercury, Mars, Venus, and hypothetical minor planets, with consideration of conduction, solid-state convection, and differentiation. A variety of geological, geochemical and geophysical data is used to constrain both the present-day temperatures and the thermal histories of the planetary interiors. The data imply that the planets were heated during or shortly after formation and that all the terrestrial planets started differentiating early in their history. The size of the planet is the primary factor in determining its present-day thermal state. A planetary body with radius less than 1000 km is unlikely to reach melting, given heat source concentrations similar to terrestrial values and in the absence of intensive early heating.

  1. 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.

  2. 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

  3. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part I: Source term estimation and local-scale atmospheric dispersion in early phase of the accident.

    PubMed

    Katata, Genki; Ota, Masakazu; Terada, Hiroaki; Chino, Masamichi; Nagai, Haruyasu

    2012-07-01

    The atmospheric release of (131)I and (137)Cs in the early phase of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident from March 12 to 14, 2011 was estimated by combining environmental data with atmospheric dispersion simulations under the assumption of a unit release rate (1 Bq h(-1)). For the simulation, WSPEEDI-II computer-based nuclear emergency response system was used. Major releases of (131)I (>10(15) Bq h(-1)) were estimated when air dose rates increased in FNPP1 during the afternoon on March 12 after the hydrogen explosion of Unit 1 and late at night on March 14. The high-concentration plumes discharged during these periods flowed to the northwest and south-southwest directions of FNPP1, respectively. These plumes caused a large amount of dry deposition on the ground surface along their routes. Overall, the spatial pattern of (137)Cs and the increases in the air dose rates observed at the monitoring posts around FNPP1 were reproduced by WSPEEDI-II using estimated release rates. The simulation indicated that air dose rates significantly increased in the south-southwest region of FNPP1 by dry deposition of the high-concentration plume discharged from the night of March 14 to the morning of March 15. PMID:22406754

  4. 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.

  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. Limiting future atmospheric carbon dioxide

    Microsoft Academic Search

    Jorge L. Sarmiento; C. L. Quere; Stephen W. Pacala

    1995-01-01

    We estimate anthropogenic carbon emissions required to stabilize future atmospheric COâ at various levels ranging from 350 ppm to 750 ppm. Over the next three centuries, uptake by the ocean and terrestrial biosphere would permit emissions to be 3 to 6 times greater than the total atmospheric increase, with each of them contributing approximately equal amounts. Owing to the nonlinear

  7. 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.

  8. 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

  9. 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

  10. NATIVE TERRESTRIAL INVERTEBRATES

    Microsoft Academic Search

    Wayne C. Gagn

    The fint collections of terrestrial invertebrates from the Hawaiian Islands were made during Captain James Cook's voyages in 1778 and 1779. Little of this material was examined scientifically other than by Fabricius (1792-1794), who described the large ichneumon wasp Eclltllromorphufuscator and the vespid hornet Odynem radulu from these collections. The ultimate disposition of specimens, and which ones subsequently survived, became

  11. 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.

  12. 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.

  13. 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

  14. Impacts of large-scale climatic disturbances on the terrestrial carbon cycle

    Microsoft Academic Search

    Tim Erbrecht; Wolfgang Lucht

    2006-01-01

    BACKGROUND: The amount of carbon dioxide in the atmosphere steadily increases as a consequence of anthropogenic emissions but with large interannual variability caused by the terrestrial biosphere. These variations in the CO2 growth rate are caused by large-scale climate anomalies but the relative contributions of vegetation growth and soil decomposition is uncertain. We use a biogeochemical model of the terrestrial

  15. The role of anthropogenic disturbance in the carbon balance of terrestrial ecosystems

    Microsoft Academic Search

    B. E. Law

    2008-01-01

    The terrestrial carbon cycle is directly affected by increasing atmospheric CO2, climate change, and disturbance, and indirectly affected by feedbacks from changes in nutrient cycling. Disturbance effects on carbon uptake by terrestrial ecosystems are often ignored in regional to continental assessments, yet this information is needed to inform policy decisions. Predictions of increased fire frequency have driven attempts to reduce

  16. The Effects of Impacts on the Climates of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Segura, T. L.; Zahnle, K.; Toon, O. B.; McKay, C. P.

    The impacts of large asteroids and comets have contributed to the climate histories of terrestrial planets. Large impact events deliver volatiles and kinetic energy to a planet, and launch debris and volatiles into its atmosphere through formation of craters. Impacts are responsible for global climate effects such as warm temperatures, release of subsurface ice, precipitation, mass extinctions, and possible runaway greenhouse atmospheres, which may last for at least centuries.

  17. 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.

  18. Effect of Solar Activity on Atmospheric Ozone

    Microsoft Academic Search

    S. Rangarajan

    1965-01-01

    THE ozone layer in the atmosphere constitutes a physical link of considerable importance between the upper atmosphere on one hand, and the lower atmosphere on the other. The former is known to respond directly to variations in the ultra-violet and corpuscular radiation from the Sun as evidenced by ionospheric and geomagnetic variations. On the other hand, the response of terrestrial

  19. 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.

  20. The extra-terrestrial vacuum-ultraviolet wavelength range

    Microsoft Academic Search

    J. Gethyn Timothy; Klaus Wilhelm; Lidong Xia

    2010-01-01

    Electromagnetic radiation in the vacuum-ultraviolet (VUV) and extra-terrestrial range at wavelengths from 10 nm to 300 nm is absorbed in the upper atmosphere by ozone, molecular and atomic oxygen, and molecular nitrogen. Observations at wavelengths down to ≈ 200 nm can be carried out from stratospheric balloons, and observations below 200 nm require space platforms operating at altitudes above 250

  1. Hypoxia, Global Warming, and Terrestrial Late Permian Extinctions

    Microsoft Academic Search

    Raymond B. Huey; Peter D. Ward

    2005-01-01

    A catastrophic extinction occurred at the end of the Permian Period. However, baseline extinction rates appear to have been elevated even before the final catastrophe, suggesting sustained environmental degradation. For terrestrial vertebrates during the Late Permian, the combination of a drop in atmospheric oxygen plus climate warming would have induced hypoxic stress and consequently compressed altitudinal ranges to near sea

  2. Terrestrial solar spectral modeling tools and applications for photovoltaic devices

    Microsoft Academic Search

    D. R. Myers; K. E. Emery; C. Gueymard

    2002-01-01

    Variations in terrestrial spectral irradiance on photovoltaic devices can be an important consideration in photovoltaic device design and performance. This paper describes three available atmospheric transmission models, MODTRAN, SMARTS2, and SPCTRAL2. We describe the basics of their operation and performance, and applications in the photovoltaic community. Examples of model input and output data and comparisons between the model results for

  3. Core formation and the evolution of terrestrial planets

    NASA Astrophysics Data System (ADS)

    Schmit, U.; Mohlmann, D.

    A model developed on the basis of the Safronov (1969) accretion theory in empty space is used to calculate the temperature distribution T(t,r) during the progress of core formation in terrestrial planets. The results favor a scenario based on the evolution of a gaseous disk of moderate mass and producing primordial H, He atmospheres at the end of the planet accretion.

  4. Terrestrial biogeochemical cycles: Global estimates with remote sensing

    SciTech Connect

    Schimel, D.S. [National Center for Atmospheric Research, Boulder, CO (United States)] [National Center for Atmospheric Research, Boulder, CO (United States)

    1995-01-01

    The carbon and nitrogen cycles are crucial for understanding the changing Earth system, influencing atmospheric concentrations of greenhouse gases, primary productivity of the biosphere, and biogenic emissions of reactive trace species. The carbon budget of the terrestrial biosphere has attracted special attention because of its role in atmospheric changes in carbon dioxide. The terrestrial biosphere influences atmospheric CO{sub 2} through three main modes: First, large, nearly balanced fluxes of CO{sub 2} in photosynthesis and respiration exhibit a degree of interannual variability which can influence atmospheric CO{sub 2}, at least on annual to decadal time scales. Second, land use changes release CO{sub 2} to the atmosphere. Third, poorly understood processes are likely resulting in enhanced uptake of CO{sub 2} in certain ecosystems, acting as a sink in the global carbon cycle. This sink may result from forest demographics, atmospheric N deposition, or direct CO{sub 2} fertilization, or some synergistic combination of those processes. Global estimates of terrestrial carbon cycle components requires the use of remote observations; however, the appropriate remote sensing strategies are quite different for the various components.

  5. On the chaotic nature of solar-terrestrial environment: Interplanetary Alfvén intermittency

    Microsoft Academic Search

    A. C.-L. Chian; Y. Kamide; E. L. Rempel; W. M. Santana

    2006-01-01

    We present an overview of observational and theoretical evidence of chaos and intermittency in the solar-terrestrial environment including solar dynamo, solar atmosphere, solar wind, and terrestrial magnetosphere-ionosphere-atmosphere. The chaotic nature of space plasmas is studied by a nonlinear model of Alfvén waves described by the low-dimensional limit of the derivative nonlinear Schrödinger equation given by its stationary solutions in the

  6. NSF's solar-terrestrial research program and RISE. [RISE (Radiative Inputs of the Sun to Earth)

    Microsoft Academic Search

    Schatten

    1992-01-01

    SunRISE has become a top priority proposed initiative for solar terrestrial science at NSF. NSF's priorities include People, Education, Infrastructure, and Competitiveness in Science. Within NSF's Atmospheric Division, the Solar Terrestrial (ST) Program considers the Sun as the principle driver of dynamic phenomena in the atmospheric and geospace environments. The ST [open quotes]Core[close quotes] program will place increased emphasis on

  7. Potential Biosignatures in Super-Earth Atmospheres

    Microsoft Academic Search

    H. Rauer; S. Gebauer; P. v. Paris; J. Cabrera; M. Godolt; J. L. Grenfell; A. Belu; F. Selsis; P. Hedelt; F. Schreier

    2011-01-01

    Atmospheric temperature and mixing ratio profiles of terrestrial planets vary with the spectral energy flux distribution for different types of M-dwarf stars and the planetary gravity. We investigate the resulting effects on the spectral appearance of molecular absorption bands, that are relevant as indicators for potential planetary habitability during primary and secondary eclipse for transiting terrestrial planets with Earth-like biomass

  8. 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...

  9. Application of Terrestrial Environments in Orion Assessments

    NASA Technical Reports Server (NTRS)

    Barbre, Robert E., Jr.

    2015-01-01

    This presentation summarizes the Marshall Space Flight Center Natural Environments Terrestrial and Planetary Environments (TPE) Team support to the NASA Orion space vehicle. The TPE utilizes meteorological data to assess the sensitivities of the vehicle due to the terrestrial environment. The Orion vehicle, part of the Multi-Purpose Crew Vehicle Program, is designed to carry astronauts beyond low-earth orbit and is currently undergoing a series of tests including Exploration Test Flight (EFT) - 1. The presentation describes examples of TPE support for vehicle design and several tests, as well as support for EFT-1 and planning for upcoming Exploration Missions while emphasizing the importance of accounting for the natural environment's impact to the vehicle early in the vehicle's program.

  10. 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.

  11. 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

  12. 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.

  13. A review of noble gas geochemistry in relation to early Earth history

    NASA Technical Reports Server (NTRS)

    Kurz, M. D.

    1985-01-01

    One of the most fundamental noble gas constraints on early Earth history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.

  14. 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.

  15. 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

  16. Major themes in the future of solar-terrestrial science

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Various aspects of solar-terrestrial science are briefly discussed. The evolution of the concept of the Solar-Terrestrial Observatory (STO) is discussed. Several remote sensing concepts were proposed. The capability to image global atmospheric, ionospheric, and magnetospheric phenomena was thought to hold considerable promise for understanding global processes. All groups of the workshop expressed a desire to develop a means for focusing research activities on data acquired from past space missions. International cooperation, new vantage points for viewing the Earth and the Sun, Explorer-class satellites, Space Shuttle missions, and other astronaut-associated space platform missions are discussed.

  17. Mantles of terrestrial planets immediately following magma ocean solidification

    Microsoft Academic Search

    A. L. Scheinberg; L. T. Elkins-Tanton; S. Zhong; E. Parmentier

    2010-01-01

    Energy of accretion in terrestrial planets is expected to create liquid silicate magma oceans. Their solidification processes create silicate differentiation and set the initial mantle structure for the planet. Solidification results in a compositionally unstable density profile, leading to cumulate Rayleigh-Taylor overturn in the early stages of planetary history. The pattern and timescale of overturn, in which cold, dense surface

  18. The oldest caseid synapsid from the Late Pennsylvanian of Kansas, and the evolution of herbivory in terrestrial vertebrates.

    PubMed

    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

  19. Utility Terrestrial Biodiversity Issues

    PubMed

    BREECE; WARD

    1996-11-01

    / Results from a survey of power utility biologists indicate that terrestrial biodiversity is considered a major issue 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.KEY WORDS: Biodiversity; Utilities; Rights-of-way; Terrestrial; Management PMID:8895401

  20. 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

  1. Sequestering Atmospheric Carbon Dioxide

    Microsoft Academic Search

    R. Lal

    2009-01-01

    The abrupt climate change, attributed to increase in atmospheric concentration of CO2 and other greenhouse gases, has necessitated identification of technological options to sequester CO2 into other long-lived pools. Other viable pools for C sequestration include geologic, oceanic, and the terrestrial. There is also a potential to convert CO2 into stable minerals. There are geoengineering techniques of CO2 capture and

  2. 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.

  3. Jupiter's outer atmosphere.

    NASA Technical Reports Server (NTRS)

    Brice, N. M.

    1973-01-01

    The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.

  4. A far ultraviolet imager for the International Solar-Terrestrial Physics Mission

    Microsoft Academic Search

    M. R. Torr; D. G. Torr; M. Zukic; R. B. Johnson; J. Ajello; P. Banks; K. Clark; K. Cole; C. Keffer; G. Parks; B. Tsurutani; J. Spann

    1995-01-01

    The aurorae are the result of collisions with the atmosphere of energetic particles that have their origin in the solar wind, and reach the atmosphere after having undergone varying degrees of acceleration and redistribution within the Earth's magnetosphere. The global scale phenomenon represented by the aurorae therefore contains considerable information concerning the solar-terrestrial connection. For example, by correctly measuring specific

  5. Limiting future atmospheric carbon dioxide

    SciTech Connect

    Sarmiento, J.L.; Quere, C.L.; Pacala, S.W. [Princeton Univ., NJ (United States)] [Princeton Univ., NJ (United States)

    1995-03-01

    We estimate anthropogenic carbon emissions required to stabilize future atmospheric CO{sub 2} at various levels ranging from 350 ppm to 750 ppm. Over the next three centuries, uptake by the ocean and terrestrial biosphere would permit emissions to be 3 to 6 times greater than the total atmospheric increase, with each of them contributing approximately equal amounts. Owing to the nonlinear dependence of oceanic and terrestrial biospheric uptake on CO{sub 2} concentration, the uptake by these two sinks decreases substantially at higher atmospheric CO{sub 2} levels. The uptake also decreases with increased atmospheric CO{sub 2} growth rate. All the stabilization scenarios require a substantial future reduction in emissions. 57 refs., 20 figs., 3 tabs.

  6. The Terrestrial Carbon Cycle and the Role of Historical Land Cover Change in the UVic Earth System Climate Model

    Microsoft Academic Search

    H. Matthews; A. J. Weaver; K. J. Meissner

    2004-01-01

    The behaviour of the terrestrial carbon cycle under historical and future climate change is examined using the UVic Earth System Climate Model, which includes a dynamic terrestrial vegetation and global carbon cycle model. When the model is forced by historical emissions of anthropogenic carbon dioxide the UVic ESCM reproduces well the observed increase in atmospheric CO2. When anthropogenic emissions are

  7. 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.

  8. Space Techniques Used to Measure Change in Terrestrial Waters

    NASA Astrophysics Data System (ADS)

    Cazenave, A.; Milly, P. C. D.; Douville, H.; Benveniste, J.; Kosuth, P.; Lettenmaier, D.

    2004-02-01

    Terrestrial waters-including snowpack, glaciers, water in aquifers and other geological formations, water in the plant root zone, rivers, lakes, man-made reservoirs, wetlands, and inundated areas-represent less than a mere 1% of the total amount of water on Earth. However, they have a crucial impact on terrestrial life and human needs and play a major role in climate variability. Land waters are continuously exchanged with the atmosphere and oceans in vertical and horizontal mass fluxes through evaporation, transpiration, and surface and subsurface runoff. Although it is now recognized that improved description of the terrestrial branch of the global water cycle is of major importance for climate research and for inventory and management of water resources, the global distribution and spatial-temporal variations of terrestrial waters are still poorly known because routine in situ observations are not available globally. So far, global estimates of spatial-temporal change of land water stored in soils and in the snowpack essentially rely on hydrological models, either coupled with atmosphere/ocean global circulation models and/or forced by observations.

  9. Space techniques used to measure change in terrestrial waters

    NASA Astrophysics Data System (ADS)

    2004-02-01

    Terrestrial waters—including snowpack, glaciers, water in aquifers and other geological formations, water in the plant root zone, rivers, lakes, man-made reservoirs, wetlands, and inundated areas—represent less than a mere 1% of the total amount of water on Earth. However, they have a crucial impact on terrestrial life and human needs and play a major role in climate variability.Land waters are continuously exchanged with the atmosphere and oceans in vertical and horizontal mass fluxes through evaporation, transpiration, and surface and subsurface runoff. Although it is now recognized that improved description of the terrestrial branch of the global water cycle is of major importance for climate research and for inventory and management of water resources, the global distribution and spatial-temporal variations of terrestrial waters are still poorly known because routine in situ observations are not available globally. So far, global estimates of spatial-temporal change of land water stored in soils and in the snowpack essentially rely on hydrological models, either coupled with atmosphere/ocean global circulation models and/or forced by observations.

  10. Interacting Atmospheric Plumes from Bolide Swarms

    Microsoft Academic Search

    M. B. Boslough; D. A. Crawford

    1996-01-01

    We have used the Sandia shock physics code, CTH, to simulate the interaction of atmospheric impact plumes generated by an array of simultaneous impact events on Earth. This work was stimulated by advances in the understanding of atmospheric impact processes since the impact of comet Shoemaker-Levy 9 (SL9), and by our desire to apply what we have learned to terrestrial

  11. Introduction to Circulating Atmospheres

    Microsoft Academic Search

    I. N. James

    1995-01-01

    This book gives an account of the modern view of the global circulation of the atmosphere. It accounts for the observed nature of the circulation and theories and simple models of the mechanisms that drive it. Early chapters concentrate on the classical view of the global circulation, on the processes that generate atmospheric motions, and on the dynamical constraints that

  12. Consequences of Considering Carbon/Nitrogen Interactions on the Feedbacks between Climate and the Terrestrial Carbon Cycle

    E-print Network

    Sokolov, Andrei P.

    A number of observational studies indicate that carbon sequestration by terrestrial ecosystems in a world with an atmosphere richer in carbon dioxide and a warmer climate depends on the interactions between the carbon and ...

  13. Evidence of extinct 244Pu in ancient terrestrial zircons

    NASA Astrophysics Data System (ADS)

    Harrison, T. M.; Turner, G.; Holland, G.; Gilmour, J. D.; Mojzsis, S. J.

    2003-04-01

    The Pu/U ratio of the early Earth is an important parameter in models of mantle evolution based on noble gas isotopes. Current estimates assume the Earth accreted with a chondritic Pu/U and are based on analyses of the chondrite St Severin and the achondrite Angra dos Reis. These estimates are poorly constrained, ranging from 0.004 to 0.008. On account of its short, 82 Ma, half-life, 244Pu was essentially extinct 3,900 Ma ago, and consequently there exists no reliable measurement of Pu/U for the Earth. The discovery of zircons dating from the period when 244Pu was "live" offers the first opportunity to measure the former terrestrial abundance of 244Pu directly. Xenon isotopes are produced by spontaneous fission and, in principle, are readily distinguishable from those produced by 238U-fission (e.g. 131Xe/136Xe = 0.24 and 0.08 respectively). However the expected levels of fission xenon in individual zircons, weighing 1 - 2 ?g and containing 100 - 200 ppm U, are below, or at best comparable to, the Xe blank levels (˜10-15 ccSTP) typical of conventional noble gas mass spectrometers. In order to analyse these minute amounts of xenon we have made use of a uniquely sensitive instrument, developed in Manchester, based on the principle of laser resonance ionisation. RELAX (Refrigerator Enhanced Laser Analyser for Xenon) is capable of analysing samples of only a few thousand atoms, some two orders of magnitude smaller than conventional mass spectrometers. We have carried out preliminary analyses of 4 individual 4,150 Ma zircons and one 3,600 Ma zircon from Jack Hills, Western Australia, and obtained five clear fission spectra. All but one were essentially free from significant atmospheric blank (the average 130Xe blank was 3× 10-18 ccSTP, i.e. 80 atoms). The spectra of the older zircons clearly demonstrated the presence of varying amounts of 244Pu fission xenon. The highest 131Xe/136Xe, 0.136 ± 0.003, corresponds to an initial Pu/U ratio of 0.0057. The lower ratios could result from loss of Xe after 4.0 Ga or represent U-Pu fractionation. We are currently repeating the exercise with older zircons and intend to search for correlations with REE patterns, oxygen isotopes, and the degree of U-Pb concordance, and to investigate the thermal release characteristics of the xenon. In addition to constraining the terrestrial Pu/U ratio these investigations may allow us to characterise the geochemical behaviour of Pu as a constraint on the earliest crust forming processes.

  14. Atmospheric evolution

    NASA Astrophysics Data System (ADS)

    Bolle, H.-J.

    One of the most important boundary conditions imposed on planetary formation theories by planetary atmosphere gas abundances is that the volatiles present are not likely to have undergone a hot phase during early accretion, and must therefore have been added at a later stage if such a hot phase did occur. As a consequence, and in contrast with the survival of primordial or solar abundances in such outer planets as Jupiter, the inner planets have undergone major transformations: (1) on Venus and Mars, water must have been dissociated, resulting in the escape of hydrogen; (2) carbon was probably bound chemically in the Martian crust, while (3) it could not react with Venus crustal materials because of the high temperatures generated by the greenhouse effect; and (4) on the earth, due to intermediate temperatures, the most significant change has been the generation of life, with its attendant transformation of an originally reducing atmosphere into an oxidizing one.

  15. Early Mars Climate Models

    Microsoft Academic Search

    Robert M. Haberle

    1998-01-01

    It is often stated that Mars and Earth had similar environmental conditions early in their history and that life might therefore have originated on Mars as well as on Earth. However, the atmospheric conditions required to produce and sustain a warm, wet climate on early Mars remain uncertain. State-of-the-art greenhouse models predict global mean surface temperatures early in Mars' history

  16. Bacteria Mediate Methylation of Iodine in Marine and Terrestrial Environments

    PubMed Central

    Amachi, Seigo; Kamagata, Yoichi; Kanagawa, Takahiro; Muramatsu, Yasuyuki

    2001-01-01

    Methyl iodide (CH3I) plays an important role in the natural iodine cycle and participates in atmospheric ozone destruction. However, the main source of this compound in nature is still unclear. Here we report that a wide variety of bacteria including terrestrial and marine bacteria are capable of methylating the environmental level of iodide (0.1 ?M). Of the strains tested, Rhizobium sp. strain MRCD 19 was chosen for further analysis, and it was found that the cell extract catalyzed the methylation of iodide with S-adenosyl-l-methionine as the methyl donor. These results strongly indicate that bacteria contribute to iodine transfer from the terrestrial and marine ecosystems into the atmosphere. PMID:11375186

  17. Deciphering thermal phase curves of dry, tidally locked terrestrial planets

    E-print Network

    Koll, Daniel D B

    2014-01-01

    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 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 (GCM) 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 ...

  18. Utility terrestrial biodiversity issues

    NASA Astrophysics Data System (ADS)

    Breece, Gary Allen; Ward, Bobby J.

    1996-11-01

    Results from a survey of power utility biologists indicate that terrestrial biodiversity is considered a major issue 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.

  19. 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.

  20. Proterozoic oxygen rise linked to shifting balance between seafloor and terrestrial weathering.

    PubMed

    Mills, Benjamin; Lenton, Timothy M; Watson, Andrew J

    2014-06-24

    A shift toward higher atmospheric oxygen concentration during the late Proterozoic has been inferred from multiple indirect proxies and is seen by many as a prerequisite for the emergence of complex animal life. However, the mechanisms controlling the level of oxygen throughout the Proterozoic and its eventual rise remain uncertain. Here we use a simple biogeochemical model to show that the balance between long-term carbon removal fluxes via terrestrial silicate weathering and ocean crust alteration plays a key role in determining atmospheric oxygen concentration. This balance may be shifted by changes in terrestrial weatherability or in the generation rate of oceanic crust. As a result, the terrestrial chemical weathering flux may be permanently altered--contrasting with the conventional view that the global silicate weathering flux must adjust to equal the volcanic CO2 degassing flux. Changes in chemical weathering flux in turn alter the long-term supply of phosphorus to the ocean, and therefore the flux of organic carbon burial, which is the long-term source of atmospheric oxygen. Hence we propose that increasing solar luminosity and a decrease in seafloor spreading rate over 1,500-500 Ma drove a gradual shift from seafloor weathering to terrestrial weathering, and a corresponding steady rise in atmospheric oxygen. Furthermore, increased terrestrial weatherability during the late Neoproterozoic may explain low temperature, increases in ocean phosphate, ocean sulfate, and atmospheric oxygen concentration at this time. PMID:24927553

  1. Proterozoic oxygen rise linked to shifting balance between seafloor and terrestrial weathering

    PubMed Central

    Mills, Benjamin; Lenton, Timothy M.; Watson, Andrew J.

    2014-01-01

    A shift toward higher atmospheric oxygen concentration during the late Proterozoic has been inferred from multiple indirect proxies and is seen by many as a prerequisite for the emergence of complex animal life. However, the mechanisms controlling the level of oxygen throughout the Proterozoic and its eventual rise remain uncertain. Here we use a simple biogeochemical model to show that the balance between long-term carbon removal fluxes via terrestrial silicate weathering and ocean crust alteration plays a key role in determining atmospheric oxygen concentration. This balance may be shifted by changes in terrestrial weatherability or in the generation rate of oceanic crust. As a result, the terrestrial chemical weathering flux may be permanently altered—contrasting with the conventional view that the global silicate weathering flux must adjust to equal the volcanic CO2 degassing flux. Changes in chemical weathering flux in turn alter the long-term supply of phosphorus to the ocean, and therefore the flux of organic carbon burial, which is the long-term source of atmospheric oxygen. Hence we propose that increasing solar luminosity and a decrease in seafloor spreading rate over 1,500–500 Ma drove a gradual shift from seafloor weathering to terrestrial weathering, and a corresponding steady rise in atmospheric oxygen. Furthermore, increased terrestrial weatherability during the late Neoproterozoic may explain low temperature, increases in ocean phosphate, ocean sulfate, and atmospheric oxygen concentration at this time. PMID:24927553

  2. Studies of the terrestrial O{sub 2} and carbon cycles in sand dune gases and in biosphere 2

    SciTech Connect

    Severinghaus, J.P.

    1995-12-31

    Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O{sub 2} composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain the fate of anthropogenic CO{sub 2}.

  3. Bio-char Sequestration in Terrestrial Ecosystems – A Review

    Microsoft Academic Search

    Johannes Lehmann; John Gaunt; Marco Rondon

    2006-01-01

    The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is proposed as a novel approach to establish\\u000a a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. Apart from positive effects in both\\u000a reducing emissions and increasing the sequestration of greenhouse gases, the production of bio-char and its application to\\u000a soil will deliver immediate benefits through

  4. 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.

  5. Mid Miocene Terrestrial Ecosystems: Information from Mammalian Herbivore Communities.

    NASA Astrophysics Data System (ADS)

    Janis, C. M.; Damuth, J.; Theodor, J. M.

    2001-05-01

    In present day ecosystems the numbers and proportions of different kinds of ecologically distinct ungulates (hoofed mammals) provide an indicator of the nature of the vegetation in the habitat. Different vegetation types (such as forest, savanna, or grassland) are characteristically associated with different arrays of ungulates, with species exhibiting differences in diet, body size, and type of digestive fermentation system. These biological attributes can also be inferred for fossil ungulate species, the first two from quantitative assessment of skull and dental anatomy, and the last from phylogenetic affinity. Thus fossil ungulate communities may be used as indicators of the vegetation types of the habitats in which they lived. Vegetation types, in turn, are determined largely by a number of physical environmental factors. Typical ungulate communities of the late early to early middle Miocene (17 - 15 Ma) from the Great Plains of North America contained a diversity of browsing (leaf-eating) and grazing (grass-eating) species, with proportions of dietary types and a diversity of body sizes indicative of a woodland savanna habitat. Paleobotanical evidence also indicates a woodland savanna type of vegetation. However, these communities included a much larger number of ungulate species than can be found in any present-day community. The "excess" ungulate species were primarily browsers. Throughout the rest of the middle Miocene both species numbers and the proportion of browsers in ungulate communities appear to have declined steadily. During this decline in browser species the numbers of grazer species remained relatively constant. Within-community species numbers comparable to the present day were attained by the late Miocene. We suggest that the early Miocene browser-rich communities, and their subsequent decline, carry an important paleoenvironmental signal. In particular, communities "over rich" in browsers may reflect higher levels of primary productivity in mid Miocene vegetation types in comparison with corresponding, structurally equivalent present-day vegetation types. The observed decline in species numbers may represent a gradual decline in terrestrial primary productivity, which would be consistent with one current hypothesis of a mid-Miocene decrease in atmospheric carbon dioxide concentrations from higher mid-Cenozoic values.

  6. Role of the ionosphere for the atmospheric evolution of planets.

    PubMed

    Yamauchi, Masatoshi; Wahlund, Jan-Erik

    2007-10-01

    We have synthesized current understanding, mainly observations, with regard to ion escape mechanisms to space from the ionosphere and exosphere of Titan and Earth-type planets, with the intent to provide an improved input for models of atmospheric evolution on early Earth and Earth-type planets and exoplanets. We focus on the role of the ionosphere and its non-linear response to solar parameters, all of which have been underestimated in current models of ancient atmospheric escape (4 billion years ago). Factors that have been overlooked include the following: (1) Much larger variation of O(+) outflow than H(+) outflow from the terrestrial ionosphere, depending on solar and geomagnetic activities (an important consideration when attempting to determine the oxidized state of the atmosphere of early Earth); (2) magnetization of the ionopause, which keeps ionospheric ions from escaping and controls many other escape processes; (3) extra ionization by, for example, the critical ionization velocity mechanism, which expands the ionosphere to greater altitudes than current models predict; and (4) the large escape of cold ions from the dense, expanded ionosphere of Titan. Here we offer, as a guideline for quantitative simulations, a qualitative diagnosis of increases or decreases of non-thermal escape related to the ionosphere for magnetized and unmagnetized planets in response to changes in solar parameters (i.e., solar EUV/FUV flux, solar wind dynamic pressure, and interplanetary magnetic field). PMID:17963477

  7. Convective storms in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2013-05-01

    The atmospheres of the planets in the Solar System have different physical properties that in some cases can be considered as extreme when compared with our own planet's more familiar atmosphere. From the tenuous and cold atmosphere of Mars to the dense and warm atmosphere of Venus in the case of the terrestrial planets, to the gigantic atmospheres of the outer planets, or the nitrogen and methane atmosphere of Saturn's moon Titan, we can find a large variety of physical environments. The comparative study of these atmospheres provides a better understanding of the physics of a geophysical fluid. In many of these worlds convective storms of different intensity appear. They are analogous to terrestrial atmospheres fed by the release of latent heat when one of the gases in the atmosphere condenses and they are therefore called moist convective storms. In many of these planets they can produce severe meteorological phenomena and by studying them in a comparative way we can aspire to get a further insight in the dynamics of these atmospheres even beyond the scope of moist convection. A classical example is the structure of the complex systems of winds in the giant planets Jupiter and Saturn. These winds are zonal and alternate in latitude but their deep structure is not accessible to direct observation. However the behaviour of large--scale convective storms vertically extending over the "weather layer" allows to study the buried roots of these winds. Another interesting atmosphere with a rather different structure of convection is Titan, a world where methane is close to its triple point in the atmosphere and can condense in bright clouds with large precipitation fluxes that may model part of the orography of the surface making Titan a world with a methane cycle similar to the hydrological cycle of Earth's atmosphere.

  8. Terrestrial nitrogen cycles: Some unanswered questions

    NASA Technical Reports Server (NTRS)

    Vitousek, P.

    1984-01-01

    Nitrogen is generally considered to be the element which most often limits the growth of plants in both natural and agricultural ecosystems. It regulates plant growth because photosynthetic rates are strongly dependent on the concentration of nitrogen in leaves, and because relatively large mounts of protein are required for cell division and growth. Yet nitrogen is abundant in the biosphere - the well-mixed pool in the atmosphere is considered inexhaustible compared to biotic demand, and the amount of already fixed organic nitrogen in soils far exceeds annual plant uptake in terrestrial ecosystems. In regions where natural vegetation is not nitrogen limited, continuous cultivation induces nitrogen deficiency. Nitrogen loss from cultivated lands is more rapid than that of other elements, and nitrogen fertilization is generally required to maintain crop yield under any continuous system. The pervasiveness of nitrogen deficiency in many natural and most managed sites is discussed.

  9. Carbon dioxide warming of the early Earth.

    PubMed

    Arrhenius, G

    1997-02-01

    Svante Arrhenius' research in atmospheric physics extended beyond the recent past and the near future states of the Earth, which today are at the center of sociopolitical attention. His plan encompassed all of the physical phenomena known at the time to relate to the formation and evolution of stars and planets. His two-volume textbook on cosmic physics is a comprehensive synopsis of the field. The inquiry into the possible cause of the ice ages and the theory of selective wavelength filter control led Arrhenius to consider the surface states of the other terrestrial planets, and of the ancient Earth before it had been modified by the emergence of life. The rapid escape of hydrogen and the equilibration with igneous rocks required that carbon in the early atmosphere prevailed mainly in oxidized form as carbon dioxide, together with other photoactive gases exerting a greenhouse effect orders of magnitude larger than in our present atmosphere. This effect, together with the ensuing chemical processes, would have set the conditions for life to evolve on our planet, seeded from spores spreading through an infinite Universe, and propelled, as Arrhenius thought, by stellar radiation pressure. PMID:11541253

  10. Carbon dioxide warming of the early Earth

    NASA Technical Reports Server (NTRS)

    Arrhenius, G.

    1997-01-01

    Svante Arrhenius' research in atmospheric physics extended beyond the recent past and the near future states of the Earth, which today are at the center of sociopolitical attention. His plan encompassed all of the physical phenomena known at the time to relate to the formation and evolution of stars and planets. His two-volume textbook on cosmic physics is a comprehensive synopsis of the field. The inquiry into the possible cause of the ice ages and the theory of selective wavelength filter control led Arrhenius to consider the surface states of the other terrestrial planets, and of the ancient Earth before it had been modified by the emergence of life. The rapid escape of hydrogen and the equilibration with igneous rocks required that carbon in the early atmosphere prevailed mainly in oxidized form as carbon dioxide, together with other photoactive gases exerting a greenhouse effect orders of magnitude larger than in our present atmosphere. This effect, together with the ensuing chemical processes, would have set the conditions for life to evolve on our planet, seeded from spores spreading through an infinite Universe, and propelled, as Arrhenius thought, by stellar radiation pressure.

  11. Intermittent Astrophysical Radiation Sources and Terrestrial Life

    NASA Astrophysics Data System (ADS)

    Melott, Adrian

    2013-04-01

    Terrestrial life is exposed to a variety of radiation sources. Astrophysical observations suggest that strong excursions in cosmic ray flux and spectral hardness are expected. Gamma-ray bursts and supernovae are expected to irradiate the atmosphere with keV to GeV photons at irregular intervals. Supernovae will produce large cosmic ray excursions, with time development varying with distance from the event. Large fluxes of keV to MeV protons from the Sun pose a strong threat to electromagnetic technology. The terrestrial record shows cosmogenic isotope excursions which are consistent with major solar proton events, and there are observations of G-stars suggesting that the rate of such events may be much higher than previously assumed. In addition there are unknown and unexplained astronomical transients which may indicate new classes of events. The Sun, supernovae, and gamma-ray bursts are all capable of producing lethal fluences, and some are expected on intervals of 10^8 years or so. The history of life on Earth is filled with mass extinctions at a variety of levels of intensity. Most are not understood. Astrophysical radiation may play a role, particularly from large increases in muon irradiation on the ground, and changes in atmospheric chemistry which deplete ozone, admitting increased solar UVB. UVB is strongly absorbed by DNA and proteins, and breaks the chemical bonds---it is a known carcinogen. High muon fluxes will also be damaging to such molecules, but experiments are needed to pin down the rate. Solar proton events which are not directly dangerous for the biota may nevertheless pose a major threat to modern electromagnetic technology through direct impact on satellites and magnetic induction of large currents in power grids, disabling transformers. We will look at the kind of events that are expected on timescales from human to geological, and their likely consequences.

  12. Evaluating carbon dioxide variability in the Community Earth System Model against atmospheric observations

    NASA Astrophysics Data System (ADS)

    Keppel-Aleks, G.; Randerson, J. T.; Lindsay, K. T.; Stephens, B. B.; Moore, J. K.; Doney, S. C.; Thornton, P. E.; Mahowald, N. M.; Hoffman, F. M.; Sweeney, C.; Tans, P. P.; Wennberg, P. O.; Wofsy, S. C.

    2012-12-01

    Changes in atmospheric CO_2 variability during the 21st century may provide insight on ecosystem responses to climate change and have implications for the design of carbon monitoring programs. We analyzed results from a fully coupled climate-carbon simulation using the Community Earth System Model (CESM1-BGC). We evaluated CO2 simulated for the historical period against surface, aircraft, and column observations. The mean annual cycle in total column atmospheric CO2 was underestimated throughout the northern hemisphere relative to TCCON observations, suggesting that the growing season net flux in the land component of CESM was too weak by 50%. Sampling CESM along HIPPO transects confirmed low growing season uptake, but also showed that spring drawdown in the Northern Hemisphere began too early. The vertical gradients in CESM generally agreed with HIPPO data and with NOAA aircraft profiles outside the growing season, but were too weak during the summer. The seasonal bias suggests that vertical transport in CAM4 (the atmospheric component of CESM) was too weak year round. Model evaluation and improvement based on atmospheric observations is crucial. The simulation of surface exchange and atmospheric transport of CO2 in coupled models such as CESM may help with the design of optimal detection strategies. For example, in the simulations of the 21st century, CESM predicted increases in the mean annual cycle of atmospheric CO2 and larger horizontal gradients. Both north-south and east-west contrasts in CO2 strengthened due to changing patterns in fossil fuel emissions and terrestrial carbon exchange, and northern hemisphere interannual variability increased as well. Our results suggest that using atmospheric observations to gain insight about changing terrestrial and ocean processes over the next several decades may become more challenging as anthropogenic contributions to variability on multiple temporal and spatial scales continue to grow.

  13. How Mars lost its atmosphere

    Microsoft Academic Search

    Kevin Zahnle

    1992-01-01

    There is a widespread suspicion that Mars thin atmosphere is in some way attributable to the planet's size. Another possibility is that the atmosphere was never degassed or outgassed in the first place. I prefer escape. Hydrodynamic escape (vigorous thermal escape) and impact erosion (expulsion of atmosphere by impacts) are two processes that should have been operative early. Although in

  14. Atmospheric Lifetime of Fossil Fuel Carbon Dioxide

    Microsoft Academic Search

    David Archer; Michael Eby; Victor Brovkin; Andy Ridgwell; Long Cao; Uwe Mikolajewicz; Ken Caldeira; Katsumi Matsumoto; Guy Munhoven; Alvaro Montenegro; Kathy Tokos

    2009-01-01

    CO2 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere, the ocean, and the terrestrial biosphere on timescales of a few centuries. However, a sizeable fraction of the CO2 remains in the atmosphere, awaiting a return to the solid earth by much slower weathering processes and deposition of CaCO3. Common measures of the atmospheric

  15. Crust-atmosphere coupling and carbon sequestration on palaeo-Mars

    NASA Astrophysics Data System (ADS)

    Macartney, Adrienne; Lee, Martin; Harkness, Patrick

    2014-05-01

    The modern surface of Mars displays evidence for past liquid water flows, with mounds and polygons in the Chryse-Acidalia region possibly indicating large bodies of ancient standing liquid [1]. For liquid water to be stable at the planet's surface, temperatures of >273.2K and a saturation water vapour pressure of >6.1 mbar are required [2]. To achieve such conditions, atmospheric pressures >1 bar CO2 have been hypothesised during the late Noachian/early Hesperian period (i.e. ~1.4-3.0 Ga [3]). Mars' currently thin (6 mbar) atmosphere poses the question of the fate of the hypothesised multi-bar CO2 atmosphere. Estimates for ~270 mbar lost to space [4], with ~5 mbar at the poles [5], leaves a minimum 750 mbar unaccounted for. The nakhlite martian meteorites display clear evidence of low water to rock (W/R) ratio isochemical silicate mineral carbonation [6]. Such carbonation processes can also be observed in basic terrestrial rock exposures, such as the Leka ophiolite, Norway [7]. Hydration and carbonation of silicate rocks is an important negative feedback process in the terrestrial carbon cycle. Significant atmospheric CO2 removal via silicate weathering partly balances the volcanic CO2 output. Peridotite contains >40% olivine, which can hydrate to form quartz, magnesite and serpentine and these reactions may be followed by carbon sequestration, forming highly alkaline travertine springs (pH>11), which have been observed in terrestrial ophiolites worldwide. Carbonation is exothermic, with the total fully carbonated solid products possessing 44% greater mass than the reactants [8]. This causes cracking [9], exposing fresh reactant surfaces, although this can be offset by expansion causing reduced porosity [10]. The raised temperatures increase reaction rates, and a positive feedback mechanism of sustained carbonation can develop. The crust of Mars is composed of similarly basic minerals, mostly basalt on the surface [11]. By investigating carbonated terrestrial analogues a deeper understanding of Martian crust-atmosphere dynamics can be achieved, possibly accounting for the loss of an early >1bar CO2 atmosphere. This research will conduct detailed petrographic observational analysis of terrestrial carbonation from collected samples of the Leka ophiolite, Norway, comparing the results with data available for Martian meteorites. It will the conduct chambered carbonation experiments on terrestrial ophiolite samples using a variety of mineralogical compositions under incrementally increased CO2 pressures, repeating with increasing ratios of CO2/SO2 mixtures. The results of objectives 1 and 2 will be synthesised to create a quantitative Martian CO2 model with variable parameters of atmospheric compositions, pressures and crustal compositions. By analysing carbon sequestration processes at differing scales and environments, carbonation rates and total silicate carbonation volumes under palaeo-martian atmospheric and mineralogical conditions can be estimated. Further mineralogical evidence to validate the model will be sought using the Curiosity Rover's Mars Science Laboratory, and collaborating with industrial partners, a new rock polishing tool will be designed, built and tested for planned use on future rovers. References: [1] Oehler, D. & Allen, C. (2012). Astrobiology 12, 601-615. [2] Martinez, G. & Renno, N. (2013). Space Science Reviews 175, 29-51. [3] Fernández-Remolar, D. et al. (2011). Meteoritics & Planetary Science 46, 1447-1469. [4] Niles, P.B. & Michalski, J.R. (2011). Lunar and Planetary Science 42, 2471. [5] Phillips, R.J. et al. (2011). Science 332, 838-841. [6] Tomkinson, T. et al. (2013). 44th Lunar and Planetary Science Conference. [7] Iyer, K. et al. (2008). Chemical Geology 249, 66-90. [8] Kelemen, P. et al. (2011). Annual Review of Earth and Planetary Sciences, Vol 39, 39, 545-576. [9] Kelemen, P. & Hirth, G. (2012). Earth and Planetary Science Letters 345, 81-89. [10] Alt, J. & Teagle, D. (1999). Geochimica et Cosmochimica Acta 63, 1527-1535. [11] Taylor, G.

  16. A Brief Review of the Application of 14C in Terrestrial Carbon Cycle Studies

    SciTech Connect

    Guilderson, T; Mcfarlane, K

    2009-10-22

    An over-arching goal of the DOE TCP program is to understand the mechanistic controls over the fate, transport, and residence time of carbon in the terrestrial biosphere. Many of the modern process and modeling studies focus on seasonal to interannual variability. However, much of the carbon on the landscape and in soils is in separate reservoirs with turnover times that are multi-decadal to millennial. It is the controls on these longer term pools or reservoirs that is a critical unknown in the face of rising GHGs and climate change and uncertainties of the terrestrial biosphere as a future global sink or source of atmospheric CO{sub 2} [eg., Friedlingstein et al., 2006; Govindasamy et al., 2005; Thompson et al., 2004]. Radiocarbon measurements, in combination with other data, can provide insight into, and constraints on, terrestrial carbon cycling. Radiocarbon (t{sub 1/2} 5730yrs) is produced naturally in the stratosphere when secondary neutrons generated by cosmic rays collide with {sup 14}N atoms [Libby 1946; Arnold and Libby, 1949]. Upon formation, {sup 14}C is rapidly oxidized to CO and then to CO{sub 2}, and is incorporated into the carbon cycle. Due to anthropogenic activities, the amount of {sup 14}C in the atmosphere doubled in the mid/late 1950s and early 1960s from its preindustrial value of {sup 14}C/{sup 12}C ratio of 1.18 x 10{sup -12} [eg., Nydal and Lovseth, 1983]. Following the atmospheric weapons test ban in 1963, the {sup 14}C/{sup 12}C ratio, has decreased due to the net isotopic exchange between the ocean and terrestrial biosphere [eg., Levin and Hessheimer, 2000] and a dilution effect due to the burning of {sup 14}C-free fossil fuel carbon, the 'Suess Effect' [Suess, 1955]. In the carbon cycle literature, radiocarbon measurements are generally reported as {Delta}{sup 14}C, which includes a correction for mass dependent fractionation [Stuiver and Polach, 1977]. In the context of carbon cycle studies radiocarbon measurements can be used to determine the 'age' and rate of change of carbon stocks or as a biogeochemical tracer to elucidate processes and pathways. It is this dual nature that can be exploited across scales in space (individual plant, plot or research site, ecosystem, regional, and global) and time (days to millennia). For example, across regional scales, {Delta}{sup 14}C measurements of atmosphere CO{sub 2} can be used to attribute carbon dioxide to sources (e.g., respiration vs. fossil fuel emissions) or sinks ( e.g,. photosynthesis), which cannot be readily inferred from concentration, net flux measurements, or {delta}{sup 13}CO{sub 2} [eg. Graven et al., 2009; Levin and Hessheimer, 2000; Turnbull et al., 2007]. At smaller scales, similar analyses can be used to elucidate the source, and 'age' of the below ground component undergoing heterotrophic respiration. Net (biome or ecosystem) uptake of carbon is the difference of two large fluxes: photosynthesis and respiration. Carbon fixation by photosynthesis is, to a large extent, a single process with theoretical underpinnings. On the other-hand, net ecosystem or biome respiration integrates microbial (heterotrophic) and plant (autotrophic) respiration. Eddy covariance methods can be used to estimate bulk CO{sub 2} fluxes but they cannot discriminate the process nor the source of the respired CO{sub 2}. It is these processes that are parameterized in predictive models and contribute to the uncertainty in the climate forcing effect of the carbon cycle in the future [Friedlingstein et al., 2006; Heimann and Reichstein, 2008].

  17. Global deforestation: contribution to atmospheric carbon dioxide

    SciTech Connect

    Woodwell, G.M.; Hobbie, J.E.; Houghton, R.A.; Melillo, J.M.; Moore, B.; Peterson, B.J.; Shaver, G.R.

    1983-12-09

    A study of effects of terrestrial biota on the amount of carbon dioxide in the atmosphere suggests that the global net release of carbon due to forest clearing between 1960 and 1980 was between 135 X 10/sup 15/ and 228 X 10/sup 15/ grams. Between 1.8 X 10/sup 15/ and 4.7 X 10/sup 15/ grams of carbon were released in 1980, of which nearly 80 percent was due to deforestation, principally in the tropics. The annual release of carbon from the biota and soils exceeded the release from fossil fuels until about 1960. Because the biotic release has been and remains much larger than is commonly assumed, the airborne fraction, usually considered to be about 50 percent of the releases from fossil fuels, was probably between 22 and 43 percent of the total carbon released in 1980. The increase in carbon dioxide in the atmosphere is thought by some to be increasing the storage of carbon in the earth's remaining forests sufficiently to offset the release from deforestation. The interpretation of the evidence presented here suggests no such effect; deforestation appears to be the dominant biotic effect on atmospheric carbon dioxide. If deforestation increases in proportion to population, the biotic release of carbon will reach 9 X 10/sup 15/ grams per year before forests are exhausted early in the next century. The possibilities for limiting the accumulation of carbon dioxide in the atmosphere through reduction in use of fossil fuels and through management of forests may be greater than is commonly assumed.

  18. Origin and evolution of planetary and satellite atmospheres

    SciTech Connect

    Atreya, S.K.; Pollack, J.B.; Matthews, M.S.

    1989-01-01

    The present volume on the origin and evolution of planet and satellite atmospheres discusses the chemistry of interstellar gas and grains, planetary accretion, cometary composition, the inventories of asteroid volatiles, key similarities and differences among the terrestrial planets' atmospheric compositions, and planets' atmospheric escape and water loss. Also discussed are planetary atmosphere-planetary interior evolutionary coupling, the atmospheric composition of the outer planets, the structure and composition of giant planet interiors, the tenuous atmosphere of Io, the sources of the atmospheres of the outer solar system's satellites, the present state and chemical evolution of the Titan, Triton, and Pluto atmospheres, and the thermal structure and heat balance of the outer planets.

  19. Physical conditions on the early Earth.

    PubMed

    Lunine, Jonathan I

    2006-10-29

    The formation of the Earth as a planet was a large stochastic process in which the rapid assembly of asteroidal-to-Mars-sized bodies was followed by a more extended period of growth through collisions of these objects, facilitated by the gravitational perturbations associated with Jupiter. The Earth's inventory of water and organic molecules may have come from diverse sources, not more than 10% roughly from comets, the rest from asteroidal precursors to chondritic bodies and possibly objects near Earth's orbit for which no representative class of meteorites exists today in laboratory collections. The final assembly of the Earth included a catastrophic impact with a Mars-sized body, ejecting mantle and crustal material to form the Moon, and also devolatilizing part of the Earth. A magma ocean and steam atmosphere (possibly with silica vapour) existed briefly in this period, but terrestrial surface waters were below the critical point within 100 million years after Earth's formation, and liquid water existed continuously on the surface within a few hundred million years. Organic material delivered by comets and asteroids would have survived, in part, this violent early period, but frequent impacts of remaining debris probably prevented the continuous habitability of the Earth for one to several hundred million years. Planetary analogues to or records of this early time when life began include Io (heat flow), Titan (organic chemistry) and Venus (remnant early granites). PMID:17008213

  20. Local Dynamics of Synoptic Waves in the Martian Atmosphere 

    E-print Network

    Kavulich, Michael J., Jr.

    2011-10-21

    The sources and sinks of energy for transient waves in the Martian atmosphere are investigated, applying diagnostic techniques developed for the analysis of terrestrial baroclinic waves to output from a Mars General Circulation Model...

  1. Redox Conditions Among the Terrestrial Planets

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    2004-01-01

    Early solar system conditions should have been extremely reducing. The redox state of the early solar nebula was determined by the H2O/H2 of the gas, which is calculated (based on solar composition) to have been about IW-5. At high temperature under such conditions, ferrous iron would exist only as a trace element in silicates and the most common type of chondritic material should have been enstatite chondrites. The observation that E-chondrites form only a subset of the chondrite suite and that the terrestrial planets (Earth, Moon, Mars, Venus, 4 Vesta) contain ferrous and ferric iron as major and minor elements, respectively, implies that either most chondritic materials formed under conditions that were not solar or that early-formed metals oxidized at low temperature, producing FeO. For example, equilibrated ordinary chondrites (by definition, common chondritic materials), by their phase assemblage of olivine, orthopyroxene and metal, must fall not far from the QFI (Quartz-Fayalite-Iron) oxygen buffer. The QFI buffer is about IW-0.5 and, as we shall see, this fo2 is close to that inferred for many materials in the inner solar system.

  2. Terrestrial accretion rates and the origin of the Moon

    Microsoft Academic Search

    A. N. Halliday

    2000-01-01

    The former decay of 182Hf to 182W (T1\\/2=9 Myr) has resulted in variations in W isotope composition that reflect early solar system time-integrated Hf\\/W ratios. The bulk silicate Earth (BSE) has non-chondritic Hf\\/W because of core formation, yet has a chondritic W isotopic composition. This is inconsistent with models that involve the completion of terrestrial accretion and core formation within

  3. Utilization of the terrestrial cyanobacteria

    NASA Astrophysics Data System (ADS)

    Katoh, Hiroshi; Tomita-Yokotani, Kaori; Furukawa, Jun; Kimura, Shunta; Yokoshima, Mika; Yamaguchi, Yuji; Takenaka, Hiroyuki

    The terrestrial, N _{2}-fixing cyanobacterium, Nostoc commune has expected to utilize for agriculture, food and terraforming cause of its extracellular polysaccharide, desiccation tolerance and nitrogen fixation. Previously, the first author indicated that desiccation related genes were analyzed and the suggested that the genes were related to nitrogen fixation and metabolisms. In this report, we suggest possibility of agriculture, using the cyanobacterium. Further, we also found radioactive compounds accumulated N. commune (cyanobacterium) in Fukushima, Japan after nuclear accident. Thus, it is investigated to decontaminate radioactive compounds from the surface soil by the cyanobacterium and showed to accumulate radioactive compounds using the cyanobacterium. We will discuss utilization of terrestrial cyanobacteria under closed environment. Keyword: Desiccation, terrestrial cyanobacteria, bioremediation, agriculture

  4. On the Origins of Atmospheres and Oceans on Rocky Planets (Invited)

    NASA Astrophysics Data System (ADS)

    Elkins-Tanton, L. T.

    2013-12-01

    The earliest atmospheres of terrestrial planets are likely a combination of degassing of their own material with captured nebular gases. Degassing occurs during giant accretionary impacts and solidification of impact-induced melt. Observations from our solar system indicate that accreting materials have sufficient volatiles to build dense atmospheres and oceans and also to populate the planetary interior with volatiles for later degassing through volcanism. Many questions remain about the efficiency of degassing magma oceans, the degree to which later impacts remove atmospheres and oceans, and the speed at which cooling steam atmospheres collapse into oceans and thus elude stripping by the energetic young star. Atmospheric stripping is an especially current topic: How much distance from the star, planetary mass, and the possibility of a magnetic dynamo protect the early atmosphere from stripping? Nonetheless, compositional data from meteorites and comets indicate that our planets obtained their water from rocky accreting materials, and observations from missions indicate that accretionary impacts do not entirely remove volatiles. The low initial water contents required to produce oceans (as little as a few hundred ppm water) indicate that rocky planets may be generally expected to produce water oceans through degassing, and that an Earth-sized planet would cool to clement conditions in just a few to tens of millions of years. Thus, rocky planets are likely to accrete with sufficient water to form early oceans. Though this first atmosphere is subsequently changed and depleted past recognition, it may also have played an important role in determining the planet's surface and habitability. Later atmospheres and oceans will inevitably comprise some combination of the volatiles degassed during accretion and cooling, volatiles delivered during the tail of accretion, and volatiles released from later volcanism.

  5. Terrestrial essential climate variables (ECVs) at a glance

    USGS Publications Warehouse

    Stitt, Susan; Dwyer, John; Dye, Dennis; Josberger, Edward

    2011-01-01

    The Global Terrestrial Observing System, Global Climate Observing System, World Meteorological Organization, and Committee on Earth Observation Satellites all support consistent global land observations and measurements. To accomplish this goal, the Global Terrestrial Observing System defined 'essential climate variables' as measurements of atmosphere, oceans, and land that are technically and economically feasible for systematic observation and that are needed to meet the United Nations Framework Convention on Climate Change and requirements of the Intergovernmental Panel on Climate Change. The following are the climate variables defined by the Global Terrestrial Observing System that relate to terrestrial measurements. Several of them are currently measured most appropriately by in-place observations, whereas others are suitable for measurement by remote sensing technologies. The U.S. Geological Survey is the steward of the Landsat archive, satellite imagery collected from 1972 to the present, that provides a potential basis for deriving long-term, global-scale, accurate, timely and consistent measurements of many of these essential climate variables.

  6. Terrestrial Paleoclimatic Impacts of an Aptian-Albian Carbon Cycle Perturbation

    Microsoft Academic Search

    G. A. Ludvigson; L. A. Gonzalez; R. M. Joeckel; A. H. Al-Suwaidi; J. I. Kirkland; S. K. Madsen

    2006-01-01

    Authigenic palustrine and pedogenic carbonates are abundantly preserved in Early Cretaceous terrestrial strata of the Cedar Mountain Formation (CMF) in the Rocky Mountain foreland of the western U.S. A coarsely- resolved terrestrial biostratigraphy and radiometric dates from interbedded volcanic ashes place the Ruby Ranch Member of the CMF in the Aptian-Albian stages (118-98 Ma). Chemostratigraphic profiling of d13C values from

  7. Solar-terrestrial research in the space station era

    NASA Technical Reports Server (NTRS)

    Chappell, Charles R.

    1987-01-01

    Because of the immense size of the solar-terrestrial system and its tightly-coupled physical nature, its study requires a carefully planned and coordinated approach using a variety of observational techniques. Of fundamental importance is the simultaneous measurement of the varying Sun, the solar wind, and the Earth's magnetosphere and atmosphere. These multiple measurements require a multi-spacecraft approach with both remote sensing of the Sun and atmosphere and in-situ measurements of the solar wind and magnetosphere. The decade of the 1990s will bring an opportunity to carry out the simultaneous set of measurements using a combination of instruments on missions such as the International Solar Terrestrial Physics Program, the GOES satellites, and the Space Station. For the first time it will be possible to determine solar variability and to sample the response of the solar wind and geospace portion of the environment in a thorough way. The potential opportunities for solar-terrestrial studies during the coming era of the Space Station are disclosed.

  8. Vital phase of space science. [solar terrestrial interactions

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1994-01-01

    Space science began with the indirect phase where the activity in space was inferred from such terrestrial phenomena as geomagnetic storms, ionospheric variations, and fluctuations in the cosmic ray intensity. The direct phase was initiated with spaceflight placing instruments directly in space and permitting the direct observation of UV and X rays, as well as precision observations of solar luminosity variations. The evidence from these many direct studies, together with the historical record of terrestrial conditions, shows that the variations of the luminosity of the Sun affect the terrestrial atmosphere at all levels, with devastating changes in climate tracking the major changes in the activity level and luminosity of the Sun. The quantification and understanding of this vital connection should be the first priority of space science and geophysics, from oceans and atmosphere through the ionosphere, magnetosphere, and all the way to the convective zone of the Sun. It becomes the vital phase of space science, focused on the basic science of the changing habitability of Earth.

  9. Benchmarking the seasonal cycle of CO2 fluxes simulated by terrestrial ecosystem models

    NASA Astrophysics Data System (ADS)

    Peng, Shushi; Ciais, Philippe; Chevallier, Frédéric; Peylin, Philippe; Cadule, Patricia; Sitch, Stephen; Piao, Shilong; Ahlström, Anders; Huntingford, Chris; Levy, Peter; Li, Xiran; Liu, Yongwen; Lomas, Mark; Poulter, Benjamin; Viovy, Nicolas; Wang, Tao; Wang, Xuhui; Zaehle, Sönke; Zeng, Ning; Zhao, Fang; Zhao, Hongfang

    2015-01-01

    We evaluated the seasonality of CO2 fluxes simulated by nine terrestrial ecosystem models of the TRENDY project against (1) the seasonal cycle of gross primary production (GPP) and net ecosystem exchange (NEE) measured at flux tower sites over different biomes, (2) gridded monthly Model Tree Ensembles-estimated GPP (MTE-GPP) and MTE-NEE obtained by interpolating many flux tower measurements with a machine-learning algorithm, (3) atmospheric CO2 mole fraction measurements at surface sites, and (4) CO2 total columns (XCO2) measurements from the Total Carbon Column Observing Network (TCCON). For comparison with atmospheric CO2 measurements, the LMDZ4 transport model was run with time-varying CO2 fluxes of each model as surface boundary conditions. Seven out of the nine models overestimate the seasonal amplitude of GPP and produce a too early start in spring at most flux sites. Despite their positive bias for GPP, the nine models underestimate NEE at most flux sites and in the Northern Hemisphere compared with MTE-NEE. Comparison with surface atmospheric CO2 measurements confirms that most models underestimate the seasonal amplitude of NEE in the Northern Hemisphere (except CLM4C and SDGVM). Comparison with TCCON data also shows that the seasonal amplitude of XCO2 is underestimated by more than 10% for seven out of the nine models (except for CLM4C and SDGVM) and that the MTE-NEE product is closer to the TCCON data using LMDZ4. From CO2 columns measured routinely at 10 TCCON sites, the constrained amplitude of NEE over the Northern Hemisphere is of 1.6 ± 0.4 gC m-2 d-1, which translates into a net CO2 uptake during the carbon uptake period in the Northern Hemisphere of 7.9 ± 2.0 PgC yr-1.

  10. Carbon balance of the terrestrial biosphere in the twentieth century: Analyses of CO2, climate and land use effects with four process-based ecosystem models

    Microsoft Academic Search

    A. D. McGuire; I. C. Prentice; N. Ramankutty; T. Reichenau; A. Schloss; H. Tian; L. J. Williams; U. Wittenberg; J. Kaplan; D. W. Kicklighter; R. A. Meier; J. M. Melillo; B. Moore

    2001-01-01

    The concurrent effects of increasing atmospheric CO2 concentration, climate variability, and cropland establishment and abandonment on terrestrial carbon storage between 1920 and 1992 were assessed using a standard simulation protocol with four process-based terrestrial biosphere models. Over the long-term (1920-1992), the simulations yielded a time history of terrestrial uptake that is consistent (within the uncertainty) with a long-term analysis based

  11. CARBON DIOXIDE SEQUESTRATION IN TERRESTRIAL ECOSYSTEMS

    EPA Science Inventory

    The terrestrial biosphere plays a prominent role in the global carbon (C) cycle. errestrial ecosystems are currently accumulating C and it appears feasible to manage existing terrestrial (forest, agronomic, desert) ecosystems to maintain or increase C storage. orest ecosystems ca...

  12. Accumulation of atmospheric sulfur in some Costa Rican soils

    USGS Publications Warehouse

    Bern, Carleton R.; Townsend, Alan R.

    2013-01-01

    Sulfur is one of the macronutrient elements whose sources to terrestrial ecosystems should shift from dominance by rock-weathering to atmospheric deposition as soils and underlying substrate undergo progressive weathering and leaching. However, the nature and timing of this transition is not well known. We investigated sources of sulfur to tropical rain forests growing on basalt-derived soils in the Osa Peninsula region of Costa Rica. Sulfur sources were examined using stable isotope ratios (?34S) and compared to chemical indices of soil development. The most weathered soils, and the forests they supported, are dominated by atmospheric sulfur, while a less weathered soil type contains both rock-derived and atmospheric sulfur. Patterns of increasing ?34S with increasing soil sulfur concentration across the landscape suggest atmospheric sulfur is accumulating, and little rock-derived sulfur has been retained. Soil sulfur, minus adsorbed sulfate, is correlated with carbon and nitrogen, implying that sulfur accumulation occurs as plants and microbes incorporate sulfur into organic matter. Only the lower depth increments of the more weathered soils contained significant adsorbed sulfate. The evidence suggests a pattern of soil development in which sulfur-bearing minerals in rock, such as sulfides, weather early relative to other minerals, and the released sulfate is leached away. Sulfur added via atmospheric deposition is retained as organic matter accumulates in the soil profile. Adsorbed sulfate accumulates later, driven by changes in soil chemistry and mineralogy. These aspects of sulfur behavior during pedogenesis in this environment may hasten the transition to dominance by atmospheric sources.

  13. Terrestrial Behavior of Ateles spp

    Microsoft Academic Search

    Christina J. Campbell; Filippo Aureli; Colin A. Chapman; Gabriel Ramos-Fernández; Kim Matthews; Sabrina E. Russo; Scott Suarez; Laura Vick

    2005-01-01

    Spider monkeys (Ateles spp.) are well known for their highly arboreal lifestyle, spending much of their time in the highest levels of the canopy and rarely venturing to the ground. To investigate terrestriality by Ateles and to illuminate the conditions under which spider monkeys venture to the ground, we analyzed ad libitum data from 5 study sites, covering 2 species

  14. Carbon dioxide and terrestrial ecosystems

    Microsoft Academic Search

    G. W. Koch; H. A. Mooney

    1996-01-01

    This book is a summary of the current research which addresses the effects of elevated carbon dioxide on terrestrial ecosystems and an identification of significant unresolved issues. Chapters address the carbon dioxide effects on trees and forests, unmanaged herbaceous ecosystems, and crops. Included are experimental studies, conceptual models, general mathematical models, dynamic simulation models.

  15. Ionospheres of the terrestrial planets

    Microsoft Academic Search

    R. W. Schunk; A. F. Nagy

    1980-01-01

    The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionspheres, the

  16. Furostanol saponins from Tribulus terrestris

    Microsoft Academic Search

    E De Combarieu; N Fuzzati; M Lovati; E Mercalli

    2003-01-01

    An HPLC-ELSD-ESI-MS method has been developed for the analysis of the steroidal saponins in the aerial parts of Tribulus terrestris. Protodioscin, a new saponin (5,6-dihydroprotodioscin, neoprotodioscin) and their respective sulfates were detected. The structure of the new compound was elucidated on the basis of NMR and ESI-MS spectral analysis.

  17. Deconvolving Terrestrial Alteration Mineral Spectral Signatures from Meteorite Reflectance Measurements

    NASA Technical Reports Server (NTRS)

    Shah, Sweta; Clark, Beth Ellen; Hiroi, Takahiro; Zolensky, Michael

    2004-01-01

    When a meteorite enters into the earth's atmosphere, it is immediately subjected to various chemical reactions between its minerals and the elements in our thick atmosphere. These reactions alter the mineralogy of the meteorites. Some examples of the altered minerals in some meteorites are summarized. If meteorites can be linked to their corresponding parent body asteroid in space, we can improve our understanding of the solar system. Spectroscopy has been used in determining the links between asteroids and meteorites. However, meteorite weathering in the Earth s atmosphere also has an effect on meteorite spectra, and altered spectra can easily confuse asteroid connections. The goal of this project is to study the mineral and spectral changes due to Earth's environment and to design a computer simulation to correct meteorite spectra for the effects of terrestrial weathering.

  18. Effects of impacts on the atmospheric evolution: Comparison between Mars, Earth, and Venus

    Microsoft Academic Search

    L. B. S. Pham; Ö. Karatekin; V. Dehant

    2011-01-01

    Classified as a terrestrial planet, Venus, Mars, and Earth are similar in several aspects such as bulk composition and density. Their atmospheres on the other hand have significant differences. Venus has the densest atmosphere, composed of CO2 mainly, with atmospheric pressure at the planet's surface 92 times that of the Earth, while Mars has the thinnest atmosphere, composed also essentially

  19. Miocene Antarctic Terrestrial Realm

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A.; Marchant, D. R.

    2009-12-01

    The discovery of several locations in the Transantarctic Mountains that contain macrofossils and pollen is transforming our understanding of late Cenozoic Antarctica. The most southerly location is on the Beardmore Glacier (85.1°S) about 500 km from the South Pole. The environment was an active glacial margin in which plants, insects and freshwater mollusks inhabited the sand and gravel bars and small lakes on an outwash plain. In addition to leaves and wood of dwarf Nothofagus (Southern Beech) shrubs, achenes of Ranunculus (Buttercup), in situ cushion growth forms of mosses and a vascular plant, the assemblages contains various exoskeletal parts of carabid and curculionid beetles and a cyclorrhaphan fly, the shells of freshwater bivalve and gastropod species and a fish tooth. Initially the deposits were assigned a Pliocene age (3.5 Ma) but a mid- to early Miocene age is more probable (c. 14 - 25 Ma) based on correlation of fossil pollen from the deposits with 39Ar/40Ar dated pollen assemblages from the McMurdo Dry Valleys locations. The oldest location within the Dry Valleys also involved an active ice margin but was part of a valley system that was completely deglaciated for intervals long enough for thick paleosols to develop. The Friis Hills fossil deposits of the Taylor Valley region (77.8°S) are at least 19.76 Ma based on the 39Ar/40Ar age of a volcanic ash bed. The valley floor during the non-glacial phases had poorly-drained soils and the extensive development of mossy mires. Wood and leaves of Nothofagus are abundant in lacustrine deposits. The silts of shallow fluvial channels contain abundant megaspores and spiky leaves of the aquatic lycopod Isoetes (Quillwort). Fossils of beetles are also present in these deposits. During the glacial phases, proglacial lakes were surrounded by dwarfed, deciduous Nothofagus shrubs. The youngest fossils recovered from the Dry Valleys are from the Olympus Range (77.5°S) with an age of 14.07 Ma. The environment was an alpine lake that formed behind a recessional moraine. The fossils are mostly those of freshwater organisms including numerous species of diatoms and an ostracod species in which the soft anatomy is preserved. The base of the lake is marked by a moss bed with exceptionally well-preserved stems and leaves of the extant species Drepanocladus longifolius. Pollen evidence from the Cape Roberts borehole in the Ross Sea basin suggests that tundra existed from the Oligocene to the Early Miocene. Fossil evidence from the Dry Valleys locations indicates that organisms that could not inhabit Antarctica today persisted until c. 14 Ma. At 14 Ma there was a shift in glacial regimes from wet- to cold-based, marking a profound and abrupt climatic shift. We hypothesize that this climate change from warmer and wetter to colder and drier conditions caused the extinction of the tundra biota. It seems probable that at least some of the mid-Miocene fossils are of organisms whose descendants evolved in Antarctica during the Paleogene or earlier. An important consequence of this hypothesis is that the Cenozoic climate of Antarctica was warm enough until the mid-Miocene to support vascular plants and insects. This research was funded by NSF OPP 0739693.

  20. Biological fixation of atmospheric nitrogen in the Mediterranean Sea

    SciTech Connect

    Bethoux, J.P.; Copin-Montegut, G.

    1986-11-01

    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 outflow) but apparently very deficient in nitrogen, despite a high N:P atomic ratio (22), in Mediterranean deep waters. This suggests the possibility of a surprisingly high rate of direct atmospheric N uptake by the Mediterranean ecosystem (possibly seagrasses Posidonia oceanica and pelagic bacterioplankton species).

  1. What can we learn about an early human influence on the global methane cycle from bipolar atmospheric CH4, ?D(CH4) and ?13CH4 measurements during the Holocene

    NASA Astrophysics Data System (ADS)

    Beck, Jonas; Bock, Michael; Schmitt, Jochen; Seth, Barbara; Blunier, Thomas; Fischer, Hubertus

    2015-04-01

    The past variation of the concentration of atmospheric methane (CH4) is observed to be generally in phase with the northern summer insolation cycle driven by the precession of the rotation axis of the Earth. However, in the mid-Holocene this regularity breaks down, and atmospheric CH4 starts to rise while the northern summer insolation continues to decline. Despite different attempts to explain this feature (e.g. contrasting hypotheses on early human influences or enhanced natural emissions in the southern tropics), an unambiguous explanation of the evolution of the atmospheric methane concentration has not yet been found. In addition to the inter-polar difference (IPD) of methane, allowing us to draw conclusions about the hemispheric imbalance of the source and sink distribution, the isotopic composition (?D and ?13C) of atmospheric CH4 provides further information about the methane cycle. Each source emits methane of a typical isotope signature, and each sink process leads to a certain isotopic fractionation and, thus, influences the isotopic composition of atmospheric methane. To exploit the full parameter set, we measured the methane isotopes on ice cores from both polar regions (NGRIP from Greenland; EDML and Talos Dome from Antarctica) and are able to calculate the inter-polar difference of ?D (IPD?D) and ?13C (IPD?13C) of methane over the Holocene. To avoid systematic errors, the samples from both hemispheres have been measured on the same system and during the same measurement campaign for each parameter. The NGRIP ?D data show a clear covariation with the long-term changes in CH4 concentrations during the Holocene. The ?D variations of 8-10 o are significantly larger than our measurement error of 2.3 o. However, the resulting IPD?D is constant within the measurement error at approximately -16.5 o (north-south) during the entire Holocene. The ?13C records (with a measurement precision of 0.13 o) show a clear decrease in ?13C of about 1.9 o and an IPD?13C of about -0.3 to -0.5 o over the early part of the Holocene and stable ?13C values for the last 5'000 years with an IPD?13C of -0.7 o. To obtain a better understanding of the processes involved in the methane cycle we assume the sink strengths (or atmospheric lifetime) and the hemispheric mixing terms to be constant, allowing us to do a unique box model inversion, which provides integrated CH4 emissions with the weight-averaged isotope signatures for both hemispheres. The inversion shows the larger changes in the methane emission rate and the corresponding isotopic signature in mid-Holocene to occur in the southern hemisphere. This may be in disagreement with the hypothesis of early human influences, since rice agriculture with their CH4 emissions are assumed to be allocated mainly in the northern tropics at that time. Further, we use atmospheric box models to assess different CH4 emission scenarios to constrain the past changes in the global methane cycle.

  2. Evolutionary History of Atmospheric CO2 during the Late Cenozoic from Fossilized Metasequoia Needles

    PubMed Central

    Wang, Yuqing; Momohara, Arata; Wang, Li; Lebreton-Anberrée, Julie; Zhou, Zhekun

    2015-01-01

    The change in ancient atmospheric CO2 concentrations provides important clues for understanding the relationship between the atmospheric CO2 concentration and global temperature. However, the lack of CO2 evolution curves estimated from a single terrestrial proxy prevents the understanding of climatic and environmental impacts due to variations in data. Thus, based on the stomatal index of fossilized Metasequoia needles, we reconstructed a history of atmospheric CO2 concentrations from middle Miocene to late Early Pleistocene when the climate changed dramatically. According to this research, atmospheric CO2 concentration was stabile around 330–350 ppmv in the middle and late Miocene, then it decreased to 278–284 ppmv during the Late Pliocene and to 277–279 ppmv during the Early Pleistocene, which was almost the same range as in preindustrial time. According to former research, this is a time when global temperature decreased sharply. Our results also indicated that from middle Miocene to Pleistocene, global CO2 level decreased by more than 50 ppmv, which may suggest that CO2 decrease and temperature decrease are coupled. PMID:26154449

  3. Asynchronous marine-terrestrial signals of the last deglacial warming in East Asia associated with low- and high-latitude climate changes.

    PubMed

    Xu, Deke; Lu, Houyuan; Wu, Naiqin; Liu, Zhenxia; Li, Tiegang; Shen, Caiming; Wang, Luo

    2013-06-11

    A high-resolution multiproxy record, including pollen, foraminifera, and alkenone paleothermometry, obtained from a single core (DG9603) from the Okinawa Trough, East China Sea (ECS), provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka. On land, the deglacial stage was characterized by rapid warming, as reflected by paleovegetation, and it began ca. 15 kaBP, consistent with the timing of the last deglacial warming in Greenland. However, sea surface temperature estimates from foraminifera and alkenone paleothermometry increased around 20-19 kaBP, as in the Western Pacific Warm Pool (WPWP). Sea surface temperatures in the Okinawa Trough were influenced mainly by heat transport from the tropical western Pacific Ocean by the Kuroshio Current, but the epicontinental vegetation of the ECS was influenced by atmospheric circulation linked to the northern high-latitude climate. Asynchronous terrestrial and marine signals of the last deglacial warming in East Asia were thus clearly related to ocean currents and atmospheric circulation. We argue that (i) early warming seawater of the WPWP, driven by low-latitude insolation and trade winds, moved northward via the Kuroshio Current and triggered marine warming along the ECS around 20-19 kaBP similar to that in the WPWP, and (ii) an almost complete shutdown of the Atlantic Meridional Overturning Circulation ca. 18-15 kaBP was associated with cold Heinrich stadial-1 and delayed terrestrial warming during the last deglacial warming until ca. 15 kaBP at northern high latitudes, and hence in East Asia. Terrestrial deglacial warming therefore lagged behind marine changes by ca. 3-4 ka. PMID:23720306

  4. TERENO - A new Network of Terrestrial Observatories for Environmental Research

    NASA Astrophysics Data System (ADS)

    Zacharias, S.; Bogena, H. R.; Kunstmann, H.; Priesack, E.; Haschberger, P.; Bens, O.; Dietrich, P.; Vereecken, H.; Papen, H.; Schmid, H. P.; Munch, J. C.; Hajnsek, I.

    2009-04-01

    Climate change and land use changes are the most important factors of global environmental change which have to be managed by the society in the next years. Global changes in terrestrial systems take place on different spatial and temporal scales. In order to address the challenges of global change, interdisciplinary research in terrestrial environmental science is of great importance. Therefore, long-term operated „Global Change Observatories" for monitoring, analyzing and predicting changing state variables and fluxes within different environmental compartments are of special importance. Several environmental research networks have already been established in order to monitor, analyse and predict the impact of global change on different compartments and/or matter cycles of the environment. Typically these environmental research networks have focused on specific research questions, and compartments, such as CarboEurope, FLUXNET and ILTER The infrastructure activity TERENO (Terrestrial Environmental Observatories), a research initiative of the Helmholtz Association, aims to establish a network of observation platforms linking terrestrial observatories in different sensitive and representative regions. The observed system consists of the subsurface environment, the land surface including the biosphere, the lower atmosphere and the anthroposphere. Hydrological units will be used as the basic scaling units in a hierarchy of evolving scales and structures ranging from the local scale to the regional scale for multi-disciplinary process studies. Terrestrial systems are extremely complex. Despite of this complexity, the terrestrial component in most process-based climate and biosphere models is typically represented in a very conceptual and often rudimentary way. Remedying this deficiency is therefore one of the most important challenges in environmental and terrestrial research, and we suggest that terrestrial observatories could be an important step towards a new quality in environmental and terrestrial research. For the first phase three terrestrial observatories in Germany have been identified: the Lower Rhine Basin, the metropolitan area Leipzig-Halle, and the Northern pre-Alps including the long-term research stations Hoeglwald and Scheyern. A fourth Observatory is planned in the German Lowland region. The concept of TERENO is illustrated by the Leipzig-Halle area. A monitoring concept for the Bode catchment - a mesoscale, lower mountain range catchment - will be described. The Bode river catchment is the central site for hydrological observation at the Leipzig-Halle TERENO study site. A integrated monitoring and research concept joining hydrological, atmospherical, biodiversity related, and soil physical research will be implemented during the next two years. This will lead to scale dependent intensive research activities on different spatial scales, allowing the development and evaluation of hydrologic scaling strategies. Hydrological monitoring will range from large scale satellite data to small scale catchment investigations on flow path, matter transport and transformation using advanced monitoring networks ranging from aerial photography and spectral analysis to non invasive geophysical investigations and sensor networks at the point scale (e.g. soil moisture).

  5. Influence of solar magnetic sector structure on terrestrial atmosphere vorticity

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Scherrer, P. H.; Svalgaard, L.; Roberts, W. O.; Olson, R. H.; Jenne, R. L.

    1973-01-01

    The solar magnetic sector structure has a sizable and reproducible influence on tropospheric and lower stratospheric vorticity. The average vorticity during winter in the Northhern Hemisphere north of 20 deg N latitude reaches a minimum approximately one day after the passing of a sector boundary, and then increases during the following two or three days. The effect is found at all heights within the troposphere, but is not prominent in the stratosphere, except at the lower levels. No single longitudinal interval appears to dominate the effect.

  6. Influence of solar magnetic sector structure on terrestrial atmospheric vorticity

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Scherrer, P. H.; Svalgaard, L.; Roberts, W. O.; Olson, R. H.; Jenne, R. L.

    1974-01-01

    The solar magnetic sector structure has a sizable and reproducible influence on tropospheric and lower stratospheric vorticity. The average vorticity during winter in the Northern Hemisphere north of 20N latitude reaches a minimum approximately one day after the passing of a sector boundary, and then increases during the following two or three days. The effect is found at all heights within the troposphere, but is not prominent in the stratosphere, except at the lower levels. No single longitudinal interval appears to dominate the effect.

  7. Atmospheric circulations of terrestrial planets orbiting low-mass stars

    Microsoft Academic Search

    Adam Edson; Sukyoung Lee; Peter Bannon; James F. Kasting; David Pollard

    2011-01-01

    Circulations and habitable zones of planets orbiting low-mass stars are investigated. Many of these planets are expected to rotate synchronously relative to their parent stars, thereby raising questions about their surface temperature distributions and habitability. We use a global circulation model to study idealized, synchronously rotating (tidally locked) planets of various rotation periods, with surfaces of all land or all

  8. Impacts of Rising Atmospheric Carbon Dioxide on Model Terrestrial Ecosystems

    E-print Network

    composition of Collembola, fungal-feeding arthropods. These results have implications for long-term feedback pooled) of Collembola per kilo- gram of Ecotron soil were significantly higher at the end of run 1

  9. Observing Strategies for the Terrestrial Planet Finder

    NASA Astrophysics Data System (ADS)

    Heap, S. R.; Lindler, D. J.

    2004-12-01

    The primary objectives of the Terrestrial Planet Finder Coronagraph (TPF-C) are to survey at least 35 nearby main-sequence stars in search of earth-like planets, and if found, to characterize them. TPF-C is unusual in that the target is not a specific object but a circumstellar region, the ``habitable zone'' = 0.7-1.5 Lbol.5 AU, which may contain several planets whose positions and (phase-dependent) brightnesses are constantly changing. In order to explore observing strategies for TPF-C, one of us (DJL) has developed a visual software tool called {\\textit tpf_planner} that enables the user to try out different approaches. We have used {\\textit tpf_planner} to simulate observations of about 50 likely TPF-C target stars. Some preliminary results include: \\begin{itemize} Planets are easier to detect around late-type stars than around early-type stars; Surveys of late-type stars can be accomplished in one observing season (6 months), whereas surveys of early-F stars could take up to four years; Many stars require only 3 visits to survey at least 90% of the habitable zone; Exo-zodi background is often the limiting factor for planet detection, but CCD read noise is usually the limiting factor for spectroscopy. The development of {\\textit tpf_planner} was funded by the TPF project. The software, which runs under most operating systems, is freely available. Please contact lindler@rockit.gsfc.nasa.gov.

  10. An Integral-Field Spectrograph for a Terrestrial Planet Finding Mission

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.

    2011-01-01

    We describe a conceptual design for an integral field spectrograph for characterizing exoplanets that we developed for NASA's Terrestrial Planet Finder Coronagraph (TPF-C), although it is equally applicable to an external-occulter mission. The spectrograph fulfills all four scientific objectives of a terrestrial planet finding mission by: (1) Spectrally characterizing the atmospheres of detected planets in search of signatures of habitability or even biological activity; (2) Directly detecting terrestrial planets in the habitable zone around nearby stars; (3) Studying all constituents of a planetary system including terrestrial and giant planets, gas and dust around sun-like stars of different ages and metallicities; (4) Enabling simultaneous, high-spatial-resolution, spectroscopy of all astrophysical sources regardless of central source luminosity, such as AGN's, proplyds, etc.

  11. A Voyage through Scales - Water in terrestrial systems

    NASA Astrophysics Data System (ADS)

    Roth, Kurt

    2015-04-01

    Terrestrial systems - a conglomerate that includes sediments, soils, and vegetation - are the third large compartment of our environment, besides the fluid systems atmosphere and ocean. All of them exhibit structures with a range of spatial and temporal scales that cover at least 9 orders of magnitude. There is a fundamental difference, however. For the fluid systems, structures and flow are one, with structures generated by the nonlinear nature of the flow and manifest in it. In contrast, the structures of terrestrial systems are predominantly formed by processes whose time scales are many orders of magnitude larger than those of the flow and transport within them. During our voyage, we will first consider the role of terrestrial systems in Earth's environmental machinery, will then stroll through their intricate multiscale architecture that covers some 14 orders of magnitude in space, and indeed also in time, have a short glimpse at the nature of the processes, predominantly the flow of water with just a nod to transport and interactions, and will finally formulate a key question: "Is an effective representation of processes in terrestrial systems possible, at a chosen scale of interest, and if so, how can it be gained?" There is no straight answer to this and we will visit several of its aspects - dissipative processes, representative and maximal averaging volumes, and time-scales -, will look at successes and failures, and will finally glance over to the working crews that attempt to blaze a way forward by dense observation networks, data assimilation, and high-performance computing. This voyage will be through Earth's terrestrial systems, with a focus on soils and porous media. It should also be informative for all who are facing nonlinear processes in hierarchically heterogeneous architectures.

  12. Introduction to Circulating Atmospheres

    NASA Astrophysics Data System (ADS)

    James, I. N.

    1995-10-01

    This book gives an account of the modern view of the global circulation of the atmosphere. It accounts for the observed nature of the circulation and theories and simple models of the mechanisms that drive it. Early chapters concentrate on the classical view of the global circulation, on the processes that generate atmospheric motions, and on the dynamical constraints that modify them. Later chapters develop more recent themes including low frequency variability and the circulation of other planetary atmospheres. Each chapter includes a set of problems.

  13. Relative importance of multiple factors on terrestrial loading of DOC to Arctic river networks

    SciTech Connect

    Kicklighter, David W. [Ecosystem Center, The] [Ecosystem Center, The; Hayes, Daniel J [ORNL] [ORNL; Mcclelland, James W [University of Texas] [University of Texas; Peterson, Bruce [Marine Biological Laboratory] [Marine Biological Laboratory; Mcguire, David [University of Alaska] [University of Alaska; Melillo, Jerry [Marine Biological Laboratory] [Marine Biological Laboratory

    2014-01-01

    Terrestrial carbon dynamics influence the contribution of dissolved organic carbon (DOC) to river networks in addition to controlling carbon fluxes between the land surface and the atmosphere. In this study, we use a biogeochemical process model to simulate the lateral transfer of DOC from land to the Arctic Ocean via riverine transport. We estimate that the pan-arctic watershed has contributed, on average, 32 Tg C/yr of DOC to the Arctic Ocean over the 20th century with most coming from the extensive area of boreal deciduous needle-leaved forests and forested wetlands in Eurasian watersheds. We also estimate that the rate of terrestrial DOC loading has been increasing by 0.037 Tg C/yr2 over the 20th century primarily as a result of increases in air temperatures and precipitation. These increases have been partially compensated by decreases in terrestrial DOC loading caused by wildfires. Other environmental factors (CO2 fertilization, ozone pollution, atmospheric nitrogen deposition, timber harvest, agriculture) are estimated to have relatively small effects on terrestrial DOC loading to arctic rivers. The effects of the various environmental factors on terrestrial carbon dynamics have both compensated and enhanced concurrent effects on hydrology to influence terrestrial DOC loading. Future increases in riverine DOC concentrations and export may occur from warming-induced increases in terrestrial DOC production associated with enhanced microbial metabolism and the exposure of additional organic matter from permafrost degradation along with decreases in water yield associated with warming-induced increases in evapotranspiration. Improvements in simulating terrestrial DOC loading to pan-arctic rivers in the future will require better information on the spatial distribution of precipitation and its temporal trends, carbon dynamics of larch-dominated ecosystems in eastern Siberia, and the role of industrial organic effluents on carbon budgets of rivers in western Russia.

  14. Characterizing extrasolar terrestrial planets with reflected, emitted and transmitted spectra.

    PubMed

    Tinetti, Giovanna

    2006-12-01

    NASA and ESA are planning missions to directly detect and characterize terrestrial planets outside our solar system (nominally NASA-Terrestrial Planet Finder and ESA-DARWIN missions). These missions will provide our first opportunity to spectroscopically study the global characteristics of those planets, and search for signs of habitability and life. We have used spatially and spectrally-resolved models to explore the observational sensitivity to changes in atmospheric and surface properties, and the detectability of surface biosignatures, in the globally averaged spectra and light-curves of the Earth. Atmospheric signatures of Earth-size exoplanets might be detected, in a near future, by stellar occultation as well. Detectability depends on planet's size, atmospheric composition, cloud cover and stellar type. According to our simulations, Earth's land vegetation signature (red-edge) is potentially visible in the disk-averaged spectra, even with cloud cover, and when the signal is averaged over the daily time scale. Marine vegetation is far more difficult to detect. We explored also the detectability of an exo-vegetation responsible for producing a signature that is red-shifted with respect to the Earth vegetation's one. PMID:17120124

  15. Early forest soils and their role in Devonian global change

    SciTech Connect

    Retallack, G.J. [Univ. of Oregon, Eugene, OR (United States)] [Univ. of Oregon, Eugene, OR (United States)

    1997-04-25

    A paleosol in the Middle Devonian Aztec Siltstone of Victoria Land, Antarctica, is the most ancient known soil of well-drained forest ecosystems. Clay enrichment and chemical weathering of subsurface horizons in this and other Devonian forested paleosols culminate a long-term increase initiated during the Silurian. From Silurian into Devonian time, red clayey calcareous paleosols show a greater volume of roots and a concomitant decline in the density of animal burrows. These trends parallel the decline in atmospheric carbon dioxide determined from isotopic records of pedogenic carbonate in these same paleosols. The drawdown of carbon dioxide began well before the Devonian appearance of coals, large logs, and diverse terrestrial plants and animals, and it did not correlate with temporal variation in volcanic or metamorphic activity. The early Paleozoic greenhouse may have been curbed by the evolution of rhizospheres with an increased ratio of primary to secondary production and by more effective silicate weathering during Silurian time. 14 refs., 3 figs.

  16. Asteroid and comet impacts on Mars and their influence on atmospheric mass evolution and habitability.

    NASA Astrophysics Data System (ADS)

    Karatekin, Özgür

    2015-04-01

    Impacts by asteroids and comets could have significant affects on the habitability and atmospheric evolution of terrestrial planets by removing part of its atmosphere, by delivering into it material and volatiles. Large impacts could have repeatedly destroyed the existing biosphere, but in the mean time new subsurface habitats have likely formed from impact induced hydrothermal systems. Early in its history, Mars could have a much denser atmosphere and higher surface temperatures to sustain the presence of stable liquid water or saline solution at the surface, as suggested by several studies. The environmental effects of a period of impact bombardment on terrestrial planets remain poorly constrained. In this study we revisit the atmospheric loss and delivery of volatiles on Mars between the end of the Noachian and present using numerical models. Following an impact, the quantity of escaped atmosphere, as well as impactor and target materials can be estimated using numerical simulations. Studies on the atmospheric loss and delivery due to impacts differ sometimes by orders of magnitude, mainly due to different equation of state and dynamical models used. The hydrocode simulations designed to simulate a single impact are not suitable to study the cumulative effect of impact erosion and delivery in the long term due to their extremely high computation costs. Instead, empirical approximations based on hydrocode simulations have been used to estimate atmospheric evolution. Comparison between different hydrocode results and atmospheric mass evolution upon impacts based on empirical models will be presented using revised model parameters. In addition, different delivery and lost mechanisms including volcanic outgassing and non-thermal escape, can be taken into account to study various atmospheric evolution scenarios. Our results suggest that impacts alone can hardly remove a significant amount of atmospheric mass over this period. Contribution of additional factors such as outgassing and non- thermal escape processes can not explain neither the presence of surface pressure larger than few hundreds of mbars 3.9 Gyr ago. Based on extreme case scenarios, maximum surface pressures at the end of the Noachian, could be as much as 0.25 bar or 1.9 bar, with and without CO2 storage into carbonate reservoirs, respectively.

  17. INTEGRATION OF TERRESTRIAL LASER SCANNER FOR GROUND NAVIGATION IN GPS-CHALLENGED ENVIRONMENTS

    Microsoft Academic Search

    X. Wang; C. Toth; D. Grejner-Brzezinska; H. Sun

    GPS\\/INS integration can provide high accuracy (centimeter level) navigation under good satellite geometry and atmospheric conditions. However, due to GPS signal blockage and accumulative error attributes of INS, a GPS\\/INS system cannot continuously maintain such high accuracy navigation during GPS outages, which may frequently happen in terrestrial applications, such as when navigating in forested areas. Imaging sensors can provide adequate

  18. Review of terrestrial and space effects on reflective surfaces and dielectrics

    Microsoft Academic Search

    F. L. Bouquet; E. F. Cuddihy; C. R. Maag

    1987-01-01

    The important effects of the atmosphere and space environment on the degradation of reflective surfaces and dielectrics are reviewed in this paper. It is becoming clear that the successful design of these systems includes an understanding of the environmental interactions, especially surface contamination effects. For reflective surfaces, both data and theoretical concepts applicable to both terrestrial solar energy systems (i.e.,

  19. Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems

    Microsoft Academic Search

    V. H. Smith; G. D. Tilman; J. C. Nekola

    1999-01-01

    In the mid-1800s, the agricultural chemist Justus von Liebig demonstrated strong positive relationships between soil nutrient supplies and the growth yields of terrestrial plants, and it has since been found that freshwater and marine plants are equally responsive to nutrient inputs. Anthropogenic inputs of nutrients to the Earth's surface and atmosphere have increased greatly during the past two centuries. This

  20. Experimental evidence that terrestrial carbon subsidies increase CO 2 flux from lake ecosystems

    Microsoft Academic Search

    Jay T. Lennon

    2004-01-01

    Subsidies are donor-controlled inputs of nutrients and energy that can affect ecosystem-level processes in a recipient environment. Lake ecosystems receive large inputs of terrestrial carbon (C) in the form of dissolved organic matter (DOM). DOM inputs may energetically subsidize heterotrophic bacteria and determine whether lakes function as sources or sinks of atmospheric CO 2. I experimentally tested this hypothesis using

  1. Terrestrial ecosystem production: A process model based on global satellite and surface data

    SciTech Connect

    Potter, C.S.; Klooster, S.A.; Matson, P.A. (NASA/Ames Research Center, Moffett Field, CA (United States)); Randerson, J.T.; Field, C.B. (Carnegie Institution of Washington, Stanford, CA (United States)); Vitousek, P.M.; Mooney, H.A. (Stanford Univ., CA (United States))

    1993-12-01

    Many basic questions about the global carbon cycle can be addressing using a modeling approach which links remote sensing, spatial data bases of climate and soils, and mechanistic understanding of atmosphere-plant-soil biogeochemistry. This paper describes the Carnegie-Ames-Stanford approach Biosphere model for study of the terrestrial carbon cycle. 112 refs., 10 figs., 11 tabs.

  2. Disk-averaged synthetic spectra and Light-curves for Terrestrial Planets

    Microsoft Academic Search

    G. Tinetti; V. S. Meadows; D. Crisp; W. Fong; T. Velusamy; M. Allen

    2004-01-01

    NASA and ESA are currently studying mission concepts for space-based observatories to search for and characterize extrasolar terrestrial planets. Any planet directly detected by this first generation of space-missions will be resolved only as point sources. Basic information can be gleaned from the object's distance from the star and its apparent brightness, but the presence of a planetary atmosphere of

  3. Vortex circulation on Venus: Dynamical similarities with terrestrial Sanjay S. Limaye,1

    E-print Network

    Kossin, James P.

    Vortex circulation on Venus: Dynamical similarities with terrestrial hurricanes Sanjay S. Limaye,1 of the atmosphere in the northern and southern hemispheres of Venus and the tropical cyclones/hurricanes on Earth. An S-shape feature detected in the center of the vortices on Venus from Pioneer Venus Orbiter and Venus

  4. An Overview of the Implications of Global Change for Natural and Managed Terrestrial Ecosystems

    Microsoft Academic Search

    Brian Walker; Will Steffen

    1997-01-01

    Global change is the net effect of individual and interactive effects of changes in land use, atmospheric composition, biological diversity, and climate. A synthesis of the past six years' activities of the Global Change and Terrestrial Ecosystems project of the IGBP (International Geosphere-Biosphere Programme) deals with global change effects as ecosystem responses and living with global change. Ecosystem responses are

  5. The Anomalous Terrestrial Gamma-ray Flash of 17 January 2004

    Microsoft Academic Search

    D. M. Smith; B. W. Grefenstette; M. Splitt; S. M. Lazarus; H. K. Rassoul; L. M. Coleman; J. R. Dwyer; E. H. Lay; R. H. Holzworth; M. B. Cohen; R. Said; T. G. Chronis; Y. Takahashi

    2006-01-01

    As far as we know, nearly all Terrestrial Gamma-Ray Flashes (TGFs) are associated with thunderstorms or at least thunderstorm-rich regions, and many have been shown to be associated with individual lightning flashes via observations of radio atmospherics. More than half of all known TGFs have been observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite. Remarkably, the

  6. CLIMATE CHANGE AND TERRESTRIAL BIOMASS: WHAT IF TREES DO NOT MIGRATE?

    EPA Science Inventory

    Climate changes induced by doubling atmospheric greenhouse gas (2XGHG) concentrations are expected to affect the distribution of global vegetation and thereby, the amount of carbon it stores. The role of the terrestrial biosphere as a source or sink for carbon during climate chan...

  7. Climatic change and the broad-scale distribution of terrestrial ecosystem complexes

    Microsoft Academic Search

    William R. Emanuel; Herman H. Shugart; Mary P. Stevenson

    1985-01-01

    The broad-scale distribution of terrestrial ecosystem complexes is determined in large part by climate and can be altered by climatic change due to natural causes or due to human activities such as those leading to increasing atmospheric CO2 concentration. Classifications that recognize the dependence of natural vegetation on climate provide one means of constructing maps to display the impact of

  8. Two sapogenins from tribulus terrestris

    Microsoft Academic Search

    Yi-Xin Xu; Hai-Sheng Chen; Wen-Yong Liu; Zheng-Bing Gu; Hua-Qing Liang

    1998-01-01

    Studies on the constituents of Tribulus terrestris L. led to the isolation of two new steroidal sapogenins, (5?, 25R)-spirostan-3,6,12-trione and 25R-spirostan-4-ene-3,6,12-trione, together with five known steroidal sapogenins, tigogenin, hecogenin, gitogenin, hecogenone, and 25R-spirostan-4-ene-3,12-dione. The structures of the new sapogenins were established on the basis of chemical and spectroscopic evidence, especially 2D NMR spectroscopic techniques.

  9. Diurnal Forcing of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Houben, Howard C.

    1997-01-01

    Much progress has been made on calculations of the Martian seasonal water cycle using the Mars Climate Model developed for this purpose. Two papers, documenting the model and the water transport results obtained with it have been published in the Journal of Geophysical Research - Planets. An additional paper describing results related to the evolution of the seasonal water cycle as a result of orbital changes was published in Advances in Space Research. Since that time, further studies have concentrated on the consequences of the soil adsorption required to match the observed water cycle and its relation to the stability of ground ice and other potential water reservoirs. Earth-related studies have concentrated on incorporating an efficient and realistic microphysical model into the Ames Stratospheric General Circulation Model used to simulate the spread of the ML Pinatubo and other volcanic clouds in the stratosphere. In addition, visualizations of the simulations are being incorporated into a video describing the UARS mission. A paper describing the new stratospheric aerosol microphysics package (and its consequences for volcanic cloud evolution) will be submitted in the near future. The paper will discuss the relative importance of condensation and coagulation to early particle growth and the separation of the cloud by sedimentation of the larger particles. A more general paper which highlights the observation that particle number densities did not increase dramatically after the ML Pinatubo eruption is planned. Simulations of atmospheric transport will be extended to include studies of terrestrial tropospheric tracers using the Fifth-Generation Penn State/NCAR Mesoscale Model.

  10. Biodiversity and biogeography of the atmosphere

    PubMed Central

    Womack, Ann M.; Bohannan, Brendan J. M.; Green, Jessica L.

    2010-01-01

    The variation of life has predominantly been studied on land and in water, but this focus is changing. There is a resurging interest in the distribution of life in the atmosphere and the processes that underlie patterns in this distribution. Here, we review our current state of knowledge about the biodiversity and biogeography of the atmosphere, with an emphasis on micro-organisms, the numerically dominant forms of aerial life. We present evidence to suggest that the atmosphere is a habitat for micro-organisms, and not purely a conduit for terrestrial and aquatic life. Building on a rich history of research in terrestrial and aquatic systems, we explore biodiversity patterns that are likely to play an important role in the emerging field of air biogeography. We discuss the possibility of a more unified understanding of the biosphere, one that links knowledge about biodiversity and biogeography in the lithosphere, hydrosphere and atmosphere. PMID:20980313

  11. Klebsormidium flaccidum genome reveals primary factors for plant terrestrial adaptation.

    PubMed

    Hori, Koichi; Maruyama, Fumito; Fujisawa, Takatomo; Togashi, Tomoaki; Yamamoto, Nozomi; Seo, Mitsunori; Sato, Syusei; Yamada, Takuji; Mori, Hiroshi; Tajima, Naoyuki; Moriyama, Takashi; Ikeuchi, Masahiko; Watanabe, Mai; Wada, Hajime; Kobayashi, Koichi; Saito, Masakazu; Masuda, Tatsuru; Sasaki-Sekimoto, Yuko; Mashiguchi, Kiyoshi; Awai, Koichiro; Shimojima, Mie; Masuda, Shinji; Iwai, Masako; Nobusawa, Takashi; Narise, Takafumi; Kondo, Satoshi; Saito, Hikaru; Sato, Ryoichi; Murakawa, Masato; Ihara, Yuta; Oshima-Yamada, Yui; Ohtaka, Kinuka; Satoh, Masanori; Sonobe, Kohei; Ishii, Midori; Ohtani, Ryosuke; Kanamori-Sato, Miyu; Honoki, Rina; Miyazaki, Daichi; Mochizuki, Hitoshi; Umetsu, Jumpei; Higashi, Kouichi; Shibata, Daisuke; Kamiya, Yuji; Sato, Naoki; Nakamura, Yasukazu; Tabata, Satoshi; Ida, Shigeru; Kurokawa, Ken; Ohta, Hiroyuki

    2014-01-01

    The colonization of land by plants was a key event in the evolution of life. Here we report the draft genome sequence of the filamentous terrestrial alga Klebsormidium flaccidum (Division Charophyta, Order Klebsormidiales) to elucidate the early transition step from aquatic algae to land plants. Comparison of the genome sequence with that of other algae and land plants demonstrate that K. flaccidum acquired many genes specific to land plants. We demonstrate that K. flaccidum indeed produces several plant hormones and homologues of some of the signalling intermediates required for hormone actions in higher plants. The K. flaccidum genome also encodes a primitive system to protect against the harmful effects of high-intensity light. The presence of these plant-related systems in K. flaccidum suggests that, during evolution, this alga acquired the fundamental machinery required for adaptation to terrestrial environments. PMID:24865297

  12. Klebsormidium flaccidum genome reveals primary factors for plant terrestrial adaptation

    PubMed Central

    Hori, Koichi; Maruyama, Fumito; Fujisawa, Takatomo; Togashi, Tomoaki; Yamamoto, Nozomi; Seo, Mitsunori; Sato, Syusei; Yamada, Takuji; Mori, Hiroshi; Tajima, Naoyuki; Moriyama, Takashi; Ikeuchi, Masahiko; Watanabe, Mai; Wada, Hajime; Kobayashi, Koichi; Saito, Masakazu; Masuda, Tatsuru; Sasaki-Sekimoto, Yuko; Mashiguchi, Kiyoshi; Awai, Koichiro; Shimojima, Mie; Masuda, Shinji; Iwai, Masako; Nobusawa, Takashi; Narise, Takafumi; Kondo, Satoshi; Saito, Hikaru; Sato, Ryoichi; Murakawa, Masato; Ihara, Yuta; Oshima-Yamada, Yui; Ohtaka, Kinuka; Satoh, Masanori; Sonobe, Kohei; Ishii, Midori; Ohtani, Ryosuke; Kanamori-Sato, Miyu; Honoki, Rina; Miyazaki, Daichi; Mochizuki, Hitoshi; Umetsu, Jumpei; Higashi, Kouichi; Shibata, Daisuke; Kamiya, Yuji; Sato, Naoki; Nakamura, Yasukazu; Tabata, Satoshi; Ida, Shigeru; Kurokawa, Ken; Ohta, Hiroyuki

    2014-01-01

    The colonization of land by plants was a key event in the evolution of life. Here we report the draft genome sequence of the filamentous terrestrial alga Klebsormidium flaccidum (Division Charophyta, Order Klebsormidiales) to elucidate the early transition step from aquatic algae to land plants. Comparison of the genome sequence with that of other algae and land plants demonstrate that K. flaccidum acquired many genes specific to land plants. We demonstrate that K. flaccidum indeed produces several plant hormones and homologues of some of the signalling intermediates required for hormone actions in higher plants. The K. flaccidum genome also encodes a primitive system to protect against the harmful effects of high-intensity light. The presence of these plant-related systems in K. flaccidum suggests that, during evolution, this alga acquired the fundamental machinery required for adaptation to terrestrial environments. PMID:24865297

  13. Natural organobromine in terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Leri, Alessandra C.; Myneni, Satish C. B.

    2012-01-01