Publications of Guy Munhoven
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See detailCarbon cycling and burial in the glacially influenced polar North Atlantic
Taylor, Justin; Tranter, Martyn; Munhoven, Guy ULiege

in Paleoceanography (2002), 17(1), 1001

We have collated published records of carbon storage (wt% calcium carbonate and organic carbon) in polar North Atlantic sediments in order to assess the role that the glacial history of Greenland and ... [more ▼]

We have collated published records of carbon storage (wt% calcium carbonate and organic carbon) in polar North Atlantic sediments in order to assess the role that the glacial history of Greenland and Fennoscandia may have had on carbon cycling in this oceanographically important region. The proportion of carbonate in sediment varies between 0 and similar to 50%, while that of organic carbon varies between 0 and similar to 2.0%. The spatial variation of the concentration and accumulation of both constituents is markedly different. Bulk accumulation shows a strong relationship with depth, distance offshore, and the location of major glacial outlets on neighboring landmasses. Therefore, ice sheet dynamics and erosion influence carbon (especially organic carbon) storage strongly during the late Weichselian (27-12 C-14 ka) via their impact on sedimentation rates and constituents. In contrast, water mass characteristics are important in determining the pattern of carbon storage during the Holocene. Carbonate fluxes to the polar North Atlantic sediment Column fall by similar to50% during glacials to similar to 1.1 x 10(13) kg kyr(-1), but organic carbon storage is maintained at or greater than interglacial levels (similar to 4.6 x 10(11) kg kyr(-1)). This represents a 100% change in the ratio of preserved inorganic to organic carbon. When combined with reduced deep water ventilation, respiration of this relatively greater organic carbon flux in both the water and sediment columns provides a good explanation for the observed periodic enhanced dissolution of carbonate in polar North Atlantic late Weichselian sections. perhaps enhancing CO2 storage in deep waters. [less ▲]

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See detailModelled glacial and non-glacial HCO3-, Si and Ge fluxes since the LGM: little potential for impact on atmospheric CO2 concentrations and a potential proxy of continental chemical erosion, the marine Ge/Si ratio
Jones, Ian W; Munhoven, Guy ULiege; Tranter, Martyn et al

in Global and Planetary Change (2002), 33(1-2), 139-153

The runoff and riverine fluxes of HCO3-, Si and Ge that arise from chemical erosion in non-glaciated terrain, are modelled at six time steps from the Last Glacial Maximum (LGM) to the present day. The ... [more ▼]

The runoff and riverine fluxes of HCO3-, Si and Ge that arise from chemical erosion in non-glaciated terrain, are modelled at six time steps from the Last Glacial Maximum (LGM) to the present day. The fluxes that arise from the Great Ice Sheets are also modelled. Terrestrial HCO3- fluxes decrease during deglaciation, largely because of the reduction in the area of the continental shelves as sea level rises. The HCO3- fluxes. and the inferred consumption of atmospheric CO2 are used as inputs to a carbon cycle model that estimates their impact on atmospheric CO2 concentrations ((CO2)-C-atms). A maximum perturbation of (CO2)-C-atms by similar to 5.5 ppm is calculated, The impact of solutes from glaciated terrain is small in comparison to those from non-glaciated terrain. Little variation in terrestrial Si and Ge fluxes is calculated (< 10%). However, the global average riverine Ge/Si ratio may be significantly perturbed if the glacial Ge/Si ratio is high. At present. variations in terrestrial chemical erosion appear to have only a reduced impact on (CO2)-C-atms and only little influence on the global Si and Ge cycle and marine Ge/Si ratios during deglaciation. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailDirect effect of ice sheets on terrestrial bicarbonate, sulphate and base cation fluxes during the last glacial cycle: minimal impact on atmospheric CO2 concentrations
Tranter, Martyn; Huybrechts, Philippe; Munhoven, Guy ULiege et al

in Chemical Geology (2002), 190(1-4), 33-44

Chemical erosion in glacial environments is normally a consequence of chemical weathering reactions dominated by sulphide oxidation linked to carbonate dissolution and the carbonation of carbonates and ... [more ▼]

Chemical erosion in glacial environments is normally a consequence of chemical weathering reactions dominated by sulphide oxidation linked to carbonate dissolution and the carbonation of carbonates and silicates. Solute fluxes from small valley glaciers are usually a linear function of discharge. Representative glacial solute concentrations can be derived from the linear association of solute flux with discharge. These representative glacial concentrations of the major ions are similar to 25% of those in global river water. A 3-D thermomechanically coupled model of the growth and decay of the Northern Hemisphere ice sheets was used to simulate glacial runoff at 100-year time steps during the last glacial cycle (130 ka to the present). The glacially derived fluxes of major cations, anions and Si over the glaciation were estimated from the product of the glacial runoff and the representative glacial concentration. A second estimate was obtained from the product of the glacial runoff and a realistic upper limit for glacial solute concentrations derived from theoretical considerations. The fluxes over the last glacial cycle are usually less than a few percent of current riverine solute fluxes to the oceans. The glacial fluxes were used to provide input to an oceanic carbon cycling model that also calculates changes in atmospheric CO2. The potential change in atmospheric CO2 concentrations over the last glacial cycle that arise from perturbations in glacial solute fluxes are insignificant, being < 1 ppm. [less ▲]

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See detailGlacial-interglacial atmospheric CO2 variations
Munhoven, Guy ULiege

in Explaining Glacial/Interglacial CO2 changes (2000)

A review of the observed glacial-interglacial variations of CO2 in the atmosphere is made. The different hypotheses proposed to date are presented. An extensive list with key references and reading ... [more ▼]

A review of the observed glacial-interglacial variations of CO2 in the atmosphere is made. The different hypotheses proposed to date are presented. An extensive list with key references and reading material is provided. [less ▲]

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See detailThe role of continental weathering in controlling atmospheric CO2 levels at glacial-interglacial time scales
Munhoven, Guy ULiege

in Explaining Glacial/Interglacial CO2 changes (2000)

The potential role of silicate weathering changes for explaining glacial-interglacial variations of CO2 in the atmosphere is discussed. Various methods for reconstructing the evolution of silicate ... [more ▼]

The potential role of silicate weathering changes for explaining glacial-interglacial variations of CO2 in the atmosphere is discussed. Various methods for reconstructing the evolution of silicate weathering rates on glacial-interglacial time scales are presented. An extensive list of key references and reading materials is provided. [less ▲]

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See detailCarbon dioxide consumption and bicarbonate production rates by continental weathering at the LGM and at present-day an update
Munhoven, Guy ULiege

in Tranter, M.; Armstrong, R.; Brun, E. (Eds.) et al Interactions Between the Cryosphere, Climate and Greenhouse Gases (1999)

We construct a range of estimates for the glacial-interglacial variations of CO2 consumption and bicarbonate production rates by continental weathering processes, using two models of continental ... [more ▼]

We construct a range of estimates for the glacial-interglacial variations of CO2 consumption and bicarbonate production rates by continental weathering processes, using two models of continental weathering in conjunction with two data sets for present-day runoff and climate results from four GCMs. Both models consistently produce 25–35% higher global CO2 consumption and 30–40% higher bicarbonate production rates at the LGM than at present-day. In terms of CO2 consumed by silicate weathering, variations calculated here are more than 2.5 times smaller than those derived from the marine Ge/Si record. Areas exposed both now and at the LGM exhibit only little change. The increased bicarbonate production (CO2 consumption) on the continental shelf exposed at the LGM overbalances the decrease due to ice cover by a factor of 3­–4 (resp. 2.3–3.7). However, large uncertainties affect the fluxes in the shelf environment, as shown by sensitivity tests regarding its lithology. [less ▲]

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See detailComparative fluxes of HCO3- and Si from glaciated and non-glaciated terrain during the last deglaciation.
Jones, I. W.; Munhoven, Guy ULiege; Tranter, M.

in Tranter, M.; Armstrong, R.; Brun, E. (Eds.) et al Interactions Between the Cryosphere, Climate and Greenhouse Gases (1999)

There is current interest in the riverine fluxes of bicarbonate and Si at the last glacial maximum (LGM), since modelling suggests that these were higher than today (Gibbs and Kump, 1994; Froelich et al ... [more ▼]

There is current interest in the riverine fluxes of bicarbonate and Si at the last glacial maximum (LGM), since modelling suggests that these were higher than today (Gibbs and Kump, 1994; Froelich et al., 1992). If this is the case, removal of atmospheric CO2 by silicate weathering is also likely to have been greater at the LGM (Munhoven and Francois, 1996), so contributing to the lower atmospheric CO2 recorded by ice cores (Barnola et al., 1987). To date, the magnitude of glacial chemical erosion on bicarbonate and Si fluxes at the LGM is poorly quantified, and the locus of the inferred doubled terrestrial Si flux is unknown. This paper aims to provide first estimates of the relative fluxes of bicarbonate and Si fluxes from ice-free and glaciated terrain for five time steps between the LGM (21ka), by extending the modelling approach of Gibbs and Kump (1994) and incorporating new data on glacial solute fluxes (Tranter et al., submitted). [less ▲]

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See detailModelling the glacial-interglacial changes in the continental biosphere
François, Louis ULiege; Delire, Christine; Warnant, Pierre ULiege et al

in Global and Planetary Change (1998), 17

A new estimate of the glacial-interglacial variations of the terrestrial carbon storage was obtained with the CARAIB biosphere model. The climatic data for the Last Glacial Maximum (LGM) necessary to ... [more ▼]

A new estimate of the glacial-interglacial variations of the terrestrial carbon storage was obtained with the CARAIB biosphere model. The climatic data for the Last Glacial Maximum (LGM) necessary to drive the biosphere model are derived from results of the ECHAM2 General Circulation Model (GCM). Six model simulations (four under typical interglacial and two under typical glacial climatic conditions) were performed to analyse the roles of different environmental changes influencing the biospheric net primary productivity (NPP) and carbon stocks. The main differences between these simulations come from the adopted CO, levels in the atmosphere, the presence or absence of crops and from changing continental boundaries. The variation of the terrestrial carbon stocks since the LGM are estimated by comparing the pre-agricultural (280 ppm of CO2, no crops, modern climate) and the full glacial simulations (200 ppm of CO2, LGM climate reconstruction). Our model predicts a global NPP increase from 38 Gt C year(-1) to 53 Gt C year(-1) during the deglaciation, a substantial part of that change being due to CO, fertilization. At the same time, the terrestrial biosphere would have fixed between 134 (neglecting CO2 fertilization effects) and 606 Gt C. The treatment of both the C-3 and C-4 photosynthetic pathways in the CARAIB model enabled us further to reconstruct the partitioning between C, and C, plants. Following our experiments, 29.7% of the total biospheric carbon stock at the LGM was C-4 material, compared to an interglacial fraction of only 19.8%. The average biospheric fractionation factor was similar to 1.5 parts per thousand less negative at LGM than it is today. Considering an atmospheric delta(13)C 0.5 +/- 0.2 parts per thousand lower at LGM than at pre-industrial times, the 606 Gt C transfer would lead to a global ocean delta(13)C shift of roughly -0.41 parts per thousand, fully consistent with currently available data. For the smaller change of 134 Gt C obtained without the CO2 fertilization effect, this shift would only be on the order of -0.10 parts per thousand. (C) 1998 Elsevier Science B,V. All rights reserved. [less ▲]

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See detailAtmospheric CO2 consumption by continental erosion: present-day controls and implications for the last glacial maximum
Ludwig, Wolfgang; Amiotte-Suchet, Philippe; Munhoven, Guy ULiege et al

in Global and Planetary Change (1998), 16-17

The export of carbon from land to sea by rivers represents a major link in the global carbon cycle, For all principal carbon forms, the main factors that control the present-day fluxes at the global scale ... [more ▼]

The export of carbon from land to sea by rivers represents a major link in the global carbon cycle, For all principal carbon forms, the main factors that control the present-day fluxes at the global scale have been determined in order to establish global budgets and to predict regional fluxes. Dissolved organic carbon fluxes are mainly related to drainage intensity, basin slope, and the amount of carbon stored in soils. Particulate organic carbon fluxes are calculated as a function of sediment yields and of drainage intensity. The consumption of atmospheric/soil CO2 by chemical rock weathering depends mainly on the rock type and on the drainage intensity. Our empirical models yield a total of 0.721 Gt of carbon (Gt C) that is exported from the continents to the oceans each year. From this figure, 0.096 Gt C come from carbonate mineral dissolution and the remaining 0.625 Gt C stem from the atmosphere (F-CO2). Of this atmospheric carbon, 33% is discharged as dissolved organic carbon, 30% as particulate organic carbon, and 37% as bicarbonate ions. Predicted inorganic carbon fluxes were further compared with observed fluxes for a set of 35 major world rivers, and possible additional climatic effects on the consumption of atmospheric CO2 by rock weathering were investigated in these river basins. Finally, we discuss the implications of our results for the river carbon fluxes and the role of continental erosion in the global carbon cycle during the last glacial maximum. [less ▲]

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See detailHST spectra of the Jovian ultraviolet aurora: Search for heavy ion precipitation
Trafton, L. M.; Dols, V.; Gérard, Jean-Claude ULiege et al

in Astrophysical Journal (1998), 507(2), 955-967

Ultraviolet spectra using Hubble Space Telescope sampled between 1250 and 1680 Angstrom, at spectral resolution less than or equal to 0.57 Angstrom are reported for characteristically bright regions of ... [more ▼]

Ultraviolet spectra using Hubble Space Telescope sampled between 1250 and 1680 Angstrom, at spectral resolution less than or equal to 0.57 Angstrom are reported for characteristically bright regions of Jupiter's morning and afternoon northern aurora. Several observed spectra exhibit sharply enhanced resolution. We interpret this as bright auroral emission foreshortened on the morning limb with a maximum intensity at least as high as 2000 kR. We have searched for evidence that the primary precipitating particles exciting the aurora include the heavy ions known to exist in Jupiter's plasma torus and magnetosphere. We have also searched for such ambient heavy ions and neutrals at rest in the auroral ionosphere, the end products of previous precipitation, excited by the auroral cascade. We argue that primary emission would be characterized by a dramatically Doppler-broadened (similar to 10-15 Angstrom) and redshifted line profile resulting from the cascade process and the angle between the line of sight and the magnetic field lines in the atmosphere. In contrast, ambient emission would be distinguished by narrow emission lines. We have modeled the theoretical sulfur and oxygen line shapes for ion precipitation and conclude that electron precipitation is responsible for most of the H-2 emissions. O ions contributed <13% of the precipitating energy flux, and S ions contributed < 50%. This dominance suggests that field-aligned magnetospheric currents are more important than energetization of energetic ions and subsequent scattering by plasma waves as a mechanism for generating the Jovian aurora. We set an upper limit over our spectra of 35-43 R to the emission from ambient oxygen and sulfur ions and their neutrals, except that for the S II 1256 triplet, the upper limit for the nominally brightest line, at 1260 Angstrom, is 74 R. Hence, we find no evidence for the accumulation of sulfur in the auroral ionosphere. A single narrow emission line from an unidentified ambient specie near 1254 Angstrom may be detected at the 4 sigma level, introducing the possibility of complex auroral aeronomy. Differences were observed in the auroral spectral hydrocarbon absorption at different locations, which cannot be interpreted without ambiguity between auroral and atmospheric structural causes. We have found that the brighter emission in an auroral sector consistently shows more spectral hydrocarbon absorption than the dimmer emission. We suggest two alternative physical explanations for this phenomenon. [less ▲]

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See detailModelling Glacial-Interglacial Atmospheric CO2 Variations: The Role of Continental Weathering.
Munhoven, Guy ULiege

Doctoral thesis (1997)

An eleven-box model of the ocean-atmosphere subsystem of the global carbon cycle is developed to study the potential contribution of continental rock weathering and of oceanic sedimentation to variations ... [more ▼]

An eleven-box model of the ocean-atmosphere subsystem of the global carbon cycle is developed to study the potential contribution of continental rock weathering and of oceanic sedimentation to variations of atmospheric CO2 pressure over glacial-interglacial time scales. The model is capable of reproducing the present-day distributions of total dissolved inorganic carbon, total alkalinity, phosphate, δ13C, and Δ14C between the various ocean basins, as well as the partial pressure of atmospheric CO2. A simple sedimentation scheme drives carbonate deposition and dissolution at the sea-floor as a function of the depths of carbonate and aragonite lysoclines in each ocean basin considered (Atlantic, Antarctic and Indo-Pacific). Carbonate accumulation on the shelf is also taken into account. Three different methods are used to calculate histories for the evolution of CO2 consumption by continental rock weathering processes, with special emphasis on silicate weathering. The first method relies on the marine 87Sr/86Sr isotopic record. We find that this record does not represent a very strong constraint, due to the large spread of the 87Sr/86Sr ratios of waters draining silicate terrains. It is possible to construct a silicate weathering history that reproduces both the strontium isotopic record and the glacial-interglacial CO2 signal. This weathering history implies that CO2 consumption by silicate rock weathering was about 120% higher during glacial than during interglacial time. The second approach is based upon the marine Ge/Si record. Taking the major uncertainties in the knowledge of the Ge and Si cycles into account, several histories for the evolution of the riverine dissolved silica fluxes are calculated from this record. The investigation of the systematics between riverine dissolved silica and bicarbonate fluxes under different weathering regimes leads us to the tentative conclusion that, although there is no correlation between dissolved silica and total bicarbonate concentrations in the major rivers, there may exist a negative correlation between weathering intensity and the ratio of bicarbonate derived from silicate weathering alone to dissolved silica. With this correlation as a working hypothesis, it is possible to interpret the dissolved silica fluxes in terms of equivalent CO2 consumption rates. The calculated histories indicate that glacial rates of CO2 consumption by chemical silicate rock weathering could have been twice, and possibly up to three times and a half, as high as they are today. When used to force the carbon cycle model, they are responsible for glacial-interglacial pCO2 variations in the atmosphere of typically 50-60 ppm and up to 95-110 ppm. These variations are superimposed to a basic oscillation of 60 ppm generated by the model, mainly in response to coral reef buildup and erosion processes. The total pCO2 signal has an amplitude of about 80-90 ppm and up to 125-135 ppm. Although these large amplitudes indicate that silicate weathering processes should be taken into account when studying glacial-interglacial changes of CO2 in the atmosphere, it also raises new problems, such as too high CO2 levels during the period from 110-70 kyr B.P. In the third approach, the glacial-interglacial histories for the consumption of CO2 and the resulting transfer of bicarbonate to the ocean are calculated from the erosion model GEM-CO2}. The required variations of the continental runoff are derived from four different GCM climatologies. We find that the CO2 consumption and river bicarbonate fluxes were about 20% higher at the last glacial maximum than at present. The exposed shelf accounts for a large fraction of the calculated LGM flux, overcompensating the 20% decrease of the two fluxes over the continent. The constructed weathering scenarios still produce pCO2 variations of about 60 ppm between glacial and interglacial times, but the contribution from variable silicate weathering to this signal is now reduced to only 12+/-5 ppm. [less ▲]

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See detailA global model of the biosphere : validation and applications to present and past climatic conditions
François, Louis ULiege; Gérard, Jean-Claude ULiege; Nemry, Bernard et al

in Sciences Géologiques. Bulletin (1997), 50(1-4), 89-107

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See detailHydrostatic flattening, core structure, and translational mode of the inner core
Denis, Carlo; Rogister, Yves; Amalvict, Martine et al

in Physics of the Earth and Planetary Interiors (1997), 99(3-4), 195-206

Modern Earth models are constrained by an inertia coefficient y*=J(2)/H approximate to 0.3308 which leads to a so-called 'hydrostatic' flattening f(hyd) approximate to 1/299.9. The latter is in rather ... [more ▼]

Modern Earth models are constrained by an inertia coefficient y*=J(2)/H approximate to 0.3308 which leads to a so-called 'hydrostatic' flattening f(hyd) approximate to 1/299.9. The latter is in rather large disagreement with the observed flattening f approximate to 1/298.3. We show that a more satisfactory value of the inertia coefficient for constraining a standard Earth model is y approximate to 0.332, consistent with a hydrostatic flattening of about 1/298.6. The change of the value of the inertia coefficient from about 0.331 to about 0.332 significantly alters the density structure of the core, notably the density jump at the inner core boundary. It brings, as a by-produce, the hydrostatic values of J(2) and H to better agreement with the observed values than is presently thought, and most probably leads for the Slichter mode to a period of much longer than 5.42 h, which is the value computed for PREM. [less ▲]

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See detailGlacial-interglacial variability of atmospheric CO2 due to changing continental silicate rock weathering: A model study
Munhoven, Guy ULiege; Francois, Louis ULiege

in Journal of Geophysical Research (1996), 101(D16), 21423-21437

An 11-box model of the oceanic carbon cycle including sedimentary processes is used to explore the role chemical weathering of continental silicate rocks might play in driving atmospheric CO2 levels on ... [more ▼]

An 11-box model of the oceanic carbon cycle including sedimentary processes is used to explore the role chemical weathering of continental silicate rocks might play in driving atmospheric CO2 levels on glacial-interglacial timescales. Histories for the consumption of CO2 by silicate rock weathering processes are derived from the marine Ge/Si record. Taking the major uncertainties in the knowledge of the Ge and Si cycles into account, several histories for the evolution of the riverine dissolved silica fluxes are calculated from this record. The investigation of the systematics between riverine dissolved silica and bicarbonate fluxes under different weathering regimes leads us to the tentative conclusion that although there is no correlation between dissolved silica and total bicarbonate concentrations in the major rivers, there may exist a negative correlation between weathering intensity and the ratio of dissolved silica to bicarbonate derived from silicate weathering alone. With this correlation as a working hypothesis, it is possible to interpret the dissolved silica fluxes in terms of equivalent CO2 consumption rates. The calculated histories indicate that glacial rates of CO2 consumption by chemical silicate rock weathering could have been twice, and possibly up to 3.5 times, as high as they are today. When used to force the carbon cycle model, they are responsible for glacial-interglacial pCO2 variations in the atmosphere of typically 50–60 ppm and up to 95–110 ppm. These variations are superimposed to a basic oscillation of 60 ppm generated by the model, mainly in response to coral reef buildup and erosion processes. The total pCO2 signal has an amplitude of about 80–90 ppm and up to 125–135 ppm. Although these large amplitudes indicate that silicate weathering processes should be taken into account when studying glacial-interglacial changes of CO2 in the atmosphere, it also raises new problems, such as too high CO2 levels during the period from 110–70 kyr B.P., requiring further study. [less ▲]

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See detailGlacial-interglacial changes in continental weathering: possible implications for atmospheric CO2
Munhoven, Guy ULiege; François, Louis ULiege

in Zahn, Rainer; Pedersen, Thomas F.; Kaminski, Michael A. (Eds.) et al Carbon Cycling in the Glacial Ocean: Constraints on the Ocean's Role in Global Change (1994)

An eleven-box model of the ocean-atmosphere subsystem of the global carbon cycle is developed to study the potential contribution of continental rock weathering and oceanic sedimentation to the variations ... [more ▼]

An eleven-box model of the ocean-atmosphere subsystem of the global carbon cycle is developed to study the potential contribution of continental rock weathering and oceanic sedimentation to the variations of the atmospheric CO2 pressure over glacial-interglacial timescales. The model is capable of reproducing the distribution of total dissolved inorganic carbon, total alkalinity, phosphate, delta C-13, and Delta C-14 between the various ocean basins today, as well as the partial pressure of atmospheric CO2. A simple sedimentation scheme at 20 different depth levels drives carbonate deposition and dissolution as a function of the depths of carbonate and aragonite lysoclines in each ocean basins considered (Atlantic, Antarctic and Indo-Pacific). The coral-reef erosion-deposition cycle is also taken into account. Furthermore, a simple cycle of oceanic strontium isotopes has been added to this model to take advantage of the Sr-87/Sr-86 data recently published by Dia et al. [1992] for the last 300,000 years. These data emphasize the importance of weathering of continental silicate rocks at glacial-interglacial timescales. They are used to construct several scenarios of changes of continental weathering over the last glacial cycles. They suggest that the flux of alkalinity delivered to the ocean from continental silicate weathering may have been substantially larger during glacial times than today. We show that such variations of continental weathering may explain at least in part the observed changes of the partial pressure of atmospheric CO2 between glacial and interglacial periods. [less ▲]

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See detailHIGH-RESOLUTION SPECTRA OF JUPITER NORTHERN AURORAL ULTRAVIOLET EMISSION WITH THE HUBBLE-SPACE-TELESCOPE
TRAFTON, L. M.; Gérard, Jean-Claude ULiege; Munhoven, Guy ULiege et al

in Astrophysical Journal (1994), 421(2), 816-827

The first spectroscopic observations of planetary aurora with the HST are reported. These include spectral regions centered on the H-2 Lyman and Werner bands of a region of Jupiter's northern aurora. The ... [more ▼]

The first spectroscopic observations of planetary aurora with the HST are reported. These include spectral regions centered on the H-2 Lyman and Werner bands of a region of Jupiter's northern aurora. The observations were made with the Goddard High Resolution Spectrograph (GHRS) using the Large Science Aperture as part of a campaign to study Jupiter at the time of the Ulysses flyby. The individual rotational-vibrational bands are resolved and the observed emissions are essentially all from H-2. A rotational-vibrational temperature for H-2 of 530 +/- 100 K is derived, a value significantly less than the 850-1100 K reported for Jovian H-3(+) in the near-infrared but consistent with the temperature reported for fundamental-band quadrupole H-2 emission. Comparison with the Faint Object Camera (FOC) images shows that the observed region was not one of the hot spots of the aurora. The results are interpreted in terms of electron impact excitation of H-2 from secondary particles generated by primaries precipitating into Jupiter's atmosphere from the magnetosphere. In the region of the aurora observed, the homopause level is found to be significantly hotter but not necessarily higher than observed at nonauroral latitudes. The equatorial H-2 dayglow spectrum was also detected; its intensity was 3.2 kR or 13% of the strength of the observed auroral emission. [less ▲]

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