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21.
By HEATHER D. GRAVEN † BRITTON B. STEPHENS THOMAS P. GUILDERSON TERESA L. CAMPOS DAVID S. SCHIMEL J. ELLIOTT CAMPBELL RALPH F. KEELING 《Tellus. Series B, Chemical and physical meteorology》2009,61(3):536-546
Measurements of Δ14 C in atmospheric CO2 are an effective method of separating CO2 additions from fossil fuel and biospheric sources or sinks of CO2 . We illustrate this technique with vertical profiles of CO2 and Δ14 C analysed in whole air flask samples collected above Colorado, USA in May and July 2004. Comparison of lower tropospheric composition to cleaner air at higher altitudes (>5 km) revealed considerable additions from respiration in the morning in both urban and rural locations. Afternoon concentrations were mainly governed by fossil fuel emissions and boundary layer depth, also showing net biospheric CO2 uptake in some cases. We estimate local industrial CO2 :CO emission ratios using in situ measurements of CO concentration. Ratios are found to vary by 100% and average 57 mole CO2 :1 mole CO, higher than expected from emissions inventories. Uncertainty in CO2 from different sources was ±1.1 to ±4.1 ppm for addition or uptake of −4.6 to 55.8 ppm, limited by Δ14 C measurement precision and uncertainty in background Δ14 C and CO2 levels. 相似文献
22.
In Spain, the birth of interest in the nation's industrial heritage dates from the 1980s and occurred alongside the process of deindustrialization. Policies concerning derelict industrial sites have shifted gradually from destruction to preservation, rehabilitation, and enhancement, and industrial heritage enhancement projects are now widespread in the country. However, a clear mismatching has arisen between institutional and academic initiatives and local communities, which exhibit widespread disinterest in or even rejection of industrial remains. This problematic situation can be related to the utilization of industrial heritage as an economic resource without paying much attention to its connections with memory and identity. Also, the mismatching is due to a positivist approach to industrial heritage whereby the monument and the museum are prioritized. We argue that projects which consider industrial remains as part of cultural landscapes might shorten the gap between the institutional and economic side of industrial heritage and its identity‐building and popular facets. 相似文献
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By C. HUNTINGFORD J. A. LOWE B. B. B. BOOTH C. D. JONES G. R. HARRIS L. K. GOHAR P. MEIR 《Tellus. Series B, Chemical and physical meteorology》2009,61(2):355-360
We have characterized the relative contributions to uncertainty in predictions of global warming amount by year 2100 in the C4MIP model ensemble ( Friedlingstein et al., 2006 ) due to both carbon cycle process uncertainty and uncertainty in the physical climate properties of the Earth system. We find carbon cycle uncertainty to be important. On average the spread in transient climate response is around 40% of that due to the more frequently debated uncertainties in equilibrium climate sensitivity and global heat capacity.
This result is derived by characterizing the influence of different parameters in a global climate-carbon cycle 'box' model that has been calibrated against the 11 General Circulation models (GCMs) and Earth system Models of Intermediate Complexity (EMICs) in the C4MIP ensemble; a collection of current state-of-the-art climate models that include an explicit representation of the global carbon cycle. 相似文献
This result is derived by characterizing the influence of different parameters in a global climate-carbon cycle 'box' model that has been calibrated against the 11 General Circulation models (GCMs) and Earth system Models of Intermediate Complexity (EMICs) in the C4MIP ensemble; a collection of current state-of-the-art climate models that include an explicit representation of the global carbon cycle. 相似文献
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PATRICK O'FLANAGAN TEODORO LASANTA MARTÍNEZ MARÍA PAZ ERREA ABAD 《Geographical review》2011,101(4):556-575
For centuries, sheep transhumance has connected the Spanish highlands with the lowlands, creating a livestock system with important social, economic, cultural, and landscape effects. About 5 million sheep were involved in transhumant movements in the mid‐1700s, but transhumance started to decay in the nineteenth century and almost disappeared in the 1970s and 1980s. In the 1980s, transhumant sheep did not number more than 25,000 in the study area; at present the number exceeds 134,000, with herders practicing both descending and ascending transhumance. In this article we provide information not only on current numbers of transhumant sheep but also on the origins and destinations of the flocks. We also confirm that the reputation of transhumance, once regarded as quaint and antiquated, has been enhanced by the ecosystem services it provides and by the cultural and heritage continuities it renders. 相似文献
26.
By C. AULAGNIER P. RAYNER P. CIAIS R. VAUTARD L. RIVIER M. RAMONET 《Tellus. Series B, Chemical and physical meteorology》2010,62(1):14-25
In this issue, Ramonet et al. revealed a positive trend in European, atmospheric CO2 concentrations relative to a marine, North Atlantic reference baseline, for the years 2001–2006. The observed build up mainly occurred during the cold season where it reaches a 0.8 ppm yr−1 at low-altitude stations to a 0.3 ppm yr−1 at mid-altitude stations. We explore the cause of this build-up using the mesoscale model CHIMERE. We first model the observed trends, using interannually varying fluxes and transport, then suppress the interannual variability in fluxes or aspects of transport to elucidate the cause. The run with no interannual variability in fluxes still matches observed trends suggesting that transport is the major cause. Separate runs varying either boundary layer height or winds show that changes in boundary layer height explain the trends at low-altitude stations within the continents while changes in wind regimes drive changes elsewhere. 相似文献
27.
By NATCHAYA PINGINTHA MONIQUE Y. LECLERC JOHN P. BEASLEY Jr. GENGSHENG ZHANG CHUCKREE SENTHONG 《Tellus. Series B, Chemical and physical meteorology》2010,62(1):47-58
This paper uses a refined soil gradient method to estimate soil CO2 efflux. Six different models are used to determine the relative gas diffusion coefficient (ξ). A weighted harmonic averaging is used to estimate the soil CO2 diffusion coefficient, yielding a better estimate of soil CO2 efflux. The resulting soil CO2 efflux results are then compared to the soil CO2 efflux measured with a soil chamber. Depending on the choice of ξ model used, the estimated soil CO2 efflux using the gradient method reasonably approximates the efflux obtained using the soil chamber method. In addition, the estimated soil CO2 efflux obtained by this improved method is well described by an exponential function of soil temperature at a depth of 0.05 m with the temperature sensitivity ( Q 10 ) of 1.81 and a linear function of soil moisture at a depth of 0.12 m, in general agreement with previous findings. These results suggest that the gradient method is a practical cost-effective means to measure soil CO2 emissions. Results from the present study suggest that the gradient method can be used successfully to measure soil CO2 efflux provided that proper attention is paid to the judicious use of the proper diffusion coefficient. 相似文献
28.
By W. VON HOYNINGEN-HUENE T. DINTER A. A. KOKHANOVSKY J. P. BURROWS M. WENDISCH E. BIERWIRTH D. MÜLLER M. DIOURI 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):206-215
Main optical characteristics of desert dust, such as phase function and single scattering albedo, have been derived from combinations of sun-/sky-radiometer and satellite measurements during the SAMUM experiment (10 May–10 June 2006) at the site Porte au Sahara (30.237°N, 5.607°W) in South Morocco. Scattering phase functions have been retrieved using combined data of spectral aerosol optical thickness (AOT) and spectral sky brightness in the almucantar, considering non-spherical light scattering. Intercomparisons of modelled top-of-atmosphere (TOA) reflectance with satellite observations of the Medium Resolution Imaging Spectrometer (MERIS) and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography () instrument have been used for the estimation of spectral single scattering albedo. For the radiative transfer calculations scattering phase functions and AOT from ground-based observations have been used. The spectral single scattering albedo ranges from 0.93 in the blue to 0.98 at 753 nm. 相似文献
29.
SHIRLEY MARIA LIMA SABINO RAQUEL FRANCO CASSINO MAKÊNIA OLIVEIRA SOARES GOMES ENEIDA MARIA ESKINAZI SANT'ANNA CRISTINA HELENA RIBEIRO ROCHA AUGUSTIN DIEGO ALVES DE OLIVEIRA 《第四纪科学杂志》2021,36(6):1028-1039
The Pandeiros wetland is a high biodiversity ecosystem located within a semiarid region of the Cerrado biome, a neotropical savanna. This large wetland is of key importance for ecological and hydrological balance in central Brazil and for the conservation of the Cerrado fauna and flora. In this study, we present the first palaeoecological investigation of the Pandeiros wetland based on pollen analysis of a palm swamp sediment core encompassing the Late Holocene. Our results show that the wetland was subject to multicentennial-scale oscillations in water availability during the Late Holocene; in particular, higher local humidity was documented between 4100 and 3100 cal a bp and from 2600 to 1000 cal a bp , and two events of drier local conditions occurred at approximately 2900 and 900 cal a bp. Our results also indicate a general decreasing trend in arboreal density in the Pandeiros River Basin from the beginning of the Late Holocene to the present, with the greatest expansion of dry forest occurring between 3600 and 3100 cal a bp. 相似文献
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By RALPH KAHN REAS PETZOLD MANFRED WENDISCH EIKE BIERWIRTH TILMAN DINTER MICHAEL ESSELBORN MARCUS FIEBIG BIRGIT HEESE PETER KNIPPERTZ DETLEF MÜLLER ALEXANDER SCHLADITZ WOLFGANG VON HOYNINGEN-HUENE 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):239-251
Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05–0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape and single-scattering albedo. For the three study days, the satellite observations (1) highlight regional gradients in the mix of dust and background spherical particles, (2) identify a dust plume most likely part of a density flow and (3) show an aerosol air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometres away. 相似文献