The carbon isotopic ratio of atmospheric carbon dioxide at Tsukuba,Japan

To find out the secular and seasonal trends of the ¹³C value and CO₂ concentration in the surface air and the determination of the ¹³C in the atmospheric CO₂ collected at Tsukuba Science City was carried out during the period from July 1981 to October 1983. The monthly average of the ¹³C value of CO₂ in the surface air collected at 1400 LMT ranged from -7.52 to \s-8.45 with an average of -7.96±0.25 and the CO₂ concentration in the air varied from 334.5 l 1^-1 to 359 l 1^-1 with an average of 347.2±6.3 l 1^-1. The ¹³C value is high in summer and low in winter and is negatively correlated with the CO₂ concentration. In general, the relationship between the ¹³C and the CO₂ concentration is explainable by a simple mixing model of two different constant carbon isotopic species but the relationship does not always follow the model. The correlation between the ¹³C value and the CO₂ concentration is low during the plant growth season and high at other times. The observed negative deviation of the ¹³C value from the simple mixing model in the plant growth season is partly due to the isotopic fractionation process which takes place in the land biota.     

Climate effects on atmospheric carbon dioxide over the last century

The buildup of atmospheric CO₂ since 1958 is surprisingly well explained by the simple premise that 57% of the industrial emissions (fossil fuel burning and cement manufacture) has remained airborne. This premise accounts well for the rise both before and after 1980 despite a decrease in the growth rate of fossil fuel CO₂ emissions, which occurred at that time, and by itself should have caused the airborne fraction to decrease. In contrast, the buildup prior to 1958 was not simply proportional to cumulative fossil fuel emissions, and notably included a period during the 1940s when CO₂ growth stalled despite continued fossil fuel emissions. Here we show that the constancy of the airborne fraction since 1958 can be in part explained by decadal variations in global land air temperature, which caused a warming-induced release of CO₂ from the land biosphere to the atmosphere. We also show that the 1940s plateau may be related to these decadal temperature variations. Furthermore, we show that there is a close connection between the phenomenology producing CO₂ variability on multidecadal and El Niño timescales.     

Seasonal variations of atmospheric sulfur dioxide and dimethylsulfide concentrations at Amsterdam Island in the southern Indian Ocean

Daily measurements of atmospheric sulfur dioxide (SO₂) concentrations were performed from March 1989 to January 1991 at Amsterdam Island (37°50 S–77°30 E), a remote site located in the southern Indian Ocean. Long-range transport of continental air masses was studied using Radon (²²²Rn) as continental tracer. Average monthly SO₂ concentrations range from less than 0.2 to 3.9 nmol m^-3 (annual average = 0.7 nmol m^-3) and present a seasonal cycle with a minimum in winter and a maximum in summer, similar to that described for atmospheric DMS concentrations measured during the same period. Clear diel correlation between atmospheric DMS and SO₂ concentrations is also observed during summer. A photochemical box model using measured atmospheric DMS concentrations as input data reproduces the seasonal variations in the measured atmospheric SO₂ concentrations within ±30%. Comparing between computed and measured SO₂ concentrations allowed us to estimate a yield of SO₂ from DMS oxidation of about 70%.     

Trace elements in the atmospheric aerosols at Delhi,North India

The total suspended particulate (TSP) levels at Delhi (north India) were measured on 116 days between February and October 1980. The observations were stratified according to season and the values of cross-correlation of the TSP and its components were evaluated. High TSP (209 g m^-3) levels were found during the summer period associated with hot and dry weather in the region and low TSP (109 g m^-3) were found during the monsoon period. Most of the TSP mass was associated with natural soil elements, such as Fe, Al, Mn, Ca, and K. Only a fraction of the mass of the TSP was comprised of elements from anthropogenic sources, e.g., Pb, Ni, Cd, Sb, Cu, and Zn. The aerosols at Delhi were potentially basic in nature, unlike those in European countries which are acidic in nature and cause acid rainfall.     

Projected impact of deep ocean carbon dioxide discharge on atmospheric CO2 concentrations

An evaluation of oceanic containment strategies for anthropogenic carbon dioxide is presented. Energy conservation is also addressed through an input hydrocarbon-fuel consumption function. The effectiveness of the proposed countermeasures is determined from atmospheric CO₂ concentration predictions. A previous box model with a diffusive deep ocean is adapted and applied to the concept of fractional CO₂ injection in 500 m deep waters. Next, the contributions of oceanic calcium carbonate sediment dissolution, and of deep seawater renewal, are included. Numerical results show that for CO₂ direct removal measures to be effective, large fractions of anthropogenic carbon dioxide have to be processed. This point favors fuel pre-processing concepts. The global model also indicates that energy conservation, i.e. a hydrocarbon-fuel consumption slowdown, remains the most effective way to mitigate the greenhouse effect, because it offers mankind a substantial time delay to implement new energy production alternatives.     

On the similarity in atmospheric fluctuations of carbon dioxide,water vapor and temperature over vegetated fields

This paper describes the similarity between atmospheric fluctuations of carbon dioxide, water vapor and temperature using data which cover a wide range of instability (0.02 < < 10). The is the Monin-Obukhov stability parameter including the humidity effect.The spectral analysis shows that the coherency between fluctuations of carbon dioxide and water vapor or temperature is very close to unity, and the phase difference is basically out of phase for whole frequency ranges analyzed. The stability dependence of the normalized standard deviation of carbon dioxide is very similar to those of water vapor and temperature. The normalized standard deviation is about 2.5 under near neutral conditions, and it decreases with increasing instability following the -1/3; power law as (-)^-1/3. The skewness factors of carbon dioxide, water vapor and temperature show a systematic departure with increasing instabilities for 0.02 < s- < 1, and level off at high instabilities for 1 < -\s < 10. The stability dependence of the flatness factors is not so clear as that noted in the standrard deviation and skewness factors. Dissipation rates of carbon dioxide, water vapor and temperature variance are well related to the spectral peak wavelength. This seems to be real since the local production and local dissipation rates are the main terms, almost balancing one another in the variance budget equations for scalar entities.     

Correlations among combustion effluent species at Barrow,Alaska: Aerosol black carbon,carbon dioxide,and methane

As part of the second Arctic Gas and Aerosol Sampling Program (AGASP II) continuous measurements of atmospheric aerosol black carbon (BC) were made at the NOAA/GMCC observatory at Barrow, Alaska (71°19N, 156°36W) during the period March 21–April 22, 1986. Black carbon is produced only by incomplete combustion of carbonaceous materials and so is a particularly useful atmospheric indicator of anthropogenic activities. The BC data have been analyzed together with the concurrent measurements of carbon dioxide (CO₂), methane (CH₄), and condensation nuclei (CN) that are routinely made at the observatory. All four species showed elevated and highly variable concentrations due to local human activities, principally in the township of Barrow, 7 km to the southwest, and at the DEW Line radar installation 1 km to the northwest. We distinguish between those periods of the record that are affected by local activities and those that are not, on the basis of the short-term (periods of up to 1 hour) variability of the continuous CO₂ and CN records, with large short-term variabilities indicating local sources. We identified seven periods of time (events) with durations ranging from 13 to 37 hours when the BC, CO₂, and CH₄ concentrations changed smoothly over time, were highly correlated with each other, and were not influenced by local activities. These events had BC/CO₂ ratios in the range (50–103)×10^–6. These ratios are dimensionless since we convert the CO₂ concentrations to units of ng m^–3 of carbon. Such values of BC/CO₂ are characteristic of the combustion effluent from large installations burning heavy fuel oil or coal, automobiles, and domestic-scale natural gas usage. We conclude that these events are indicative of air masses that have been polluted with combustion emissions in a distant location and then transported to the Arctic. In the absence of species-selective loss mechanisms, these air masses will maintain their combustion effluent signatures during the transport. The BC/CO₂ ratios found for the local combustion activities are consistent with those expected from known combustion processes.     

Probabilistic simulations of the impact of increasing leaf-level atmospheric carbon dioxide on the global land surface

Using a climate model with a sophisticated land surface scheme, simulations were conducted to explore the impact of increases in leaf-level carbon dioxide (CO₂) on evaporation, temperature and other land surface quantities. Fifty-one realizations were run, for each of four Januarys and four Julys for CO₂ concentrations at leaf-level of 280, 375, 500, 650, 840 and 1,000 ppmv. Atmospheric CO₂ concentration was held constant at 375 ppmv in all experiments. Statistically significant decreases in evaporation and increases in temperature occur in specific regions as leaf-level CO₂ is increased from 280 to 375 ppmv. These same areas expand geographically, and the magnitude of the changes increase as leaf-level CO₂ is increased further suggesting that changes are caused by the increase in leaf-level CO₂ and are not internal model variability. As leaf-level CO₂ is increased further, larger areas of the continental surface are affected by increasing amounts and a statistically significant change in precipitation is seen. The increase in leaf-level CO₂ from 280 ppmv to 375 ppmv causes statistically significant changes in the evaporation over 12% of continental surfaces in July. This increases to 25% at 500 ppmv, 35% at 650 ppmv, 41% at 840 ppmv and 47% at 1,000 ppmv. This affects temperature and rainfall by similar amounts, generally in coincident regions. An analysis of these results over key regions shows that the probability density functions of the latent heat flux and temperature are affected non-uniformly. There is a shift in the latent heat flux probability density function to lower values, mainly through the reduction in the upper tail of the distribution. The temperature probability density function shifts to higher values, mainly through an increase in the upper tail of the distribution indicating that the impact is focussed on extremes. Given that there are a suite of well evaluated land surface models that include the biogeochemical effects of increasing CO₂ we suggest that the inclusion of such a model should be a recommended component of climate models used in future assessment reports by the Intergovernmental Panel on Climate Change.     

The influence of atmospheric circulation on the occurrence of hail in the North German Lowlands

The atmospheric circulation and thermal conditions in the troposphere were analysed to identify the situations which are conductive to hail development in the North German Lowlands. They were established on the basis of the data obtained from the US National Center for Environmental Prediction/US National Center for Atmospheric Research Reanalysis database, and they included sea level pressure, 500 hPa geopotential height, the temperature at 850 and 500 hPa and HYSPLIT backward trajectories model. Daily information about hail occurrence in 16 selected stations was received from Deutscher Wetterdienst database and it covered the years 1951–2010. It was found that hail in the studied area was connected with large negative anomalies of the sea level pressure over Scandinavia and, consequently, the northwestern direction of air mass influx. In some cases, hail was associated with the northern influx, with strong negative anomalies of the temperature, and with positive anomalies of the temperature during the southern influx of air masses.     

Combined influence of atmospheric physics and soil hydrology on the simulated meteorology at the SIRTA atmospheric observatory

The identification of the land-atmosphere interactions as one of the key source of uncertainty in climate models calls for process-level assessment of the coupled atmosphere/land continental surface system in numerical climate models. To this end, we propose a novel approach and apply it to evaluate the standard and new parametrizations of boundary layer/convection/clouds in the Earth System Model (ESM) of Institut Pierre Simon Laplace (IPSL), which differentiate the IPSL-CM5A and IPSL-CM5B climate change simulations produced for the Coupled Model Inter-comparison Project phase 5 exercise. Two different land surface hydrology parametrizations are also considered to analyze different land-atmosphere interactions. Ten-year simulations of the coupled land surface/atmospheric ESM modules are confronted to observations collected at the SIRTA (Site Instrumental de Recherche par Télédection Atmosphérique), located near Paris (France). For sounder evaluation of the physical parametrizations, the grid of the model is stretched and refined in the vicinity of the SIRTA, and the large scale component of the modeled circulation is adjusted toward ERA-Interim reanalysis outside of the zoomed area. This allows us to detect situations where the parametrizations do not perform satisfactorily and can affect climate simulations at the regional/continental scale, including in full 3D coupled runs. In particular, we show how the biases in near surface state variables simulated by the ESM are explained by (1) the sensible/latent heat partitionning at the surface, (2) the low level cloudiness and its radiative impact at the surface, (3) the parametrization of turbulent transport in the surface layer, (4) the complex interplay between these processes. We also show how the new set of parametrizations can improve these biases.     

Atmospheric carbon dioxide variations at coastal site, Shibukawa, in Seto Inland Sea, Japan

Summary Four years of measurements (1980–83) of carbon dioxide at the northern coast site, Shibukawa, are presented. The data reveal well defined diurnal and seasonal variations. The amplitude of the daily carbon dioxide variation is about 30 ppm during the colder season (January–March; November–December), and about 60 ppm during the warmer season (April–October). The seasonal variation of daily minimum concentration of carbon dioxide has a maximum in the middle of summer (July–September) and a minimum in the winter months. This variation does not correspond to that expected from vegetation activity. The summer peak in carbon dioxide concentration seems to be inherent features at the coast site, Shibukawa; it is probably due to less activity of the vertical mixing under stable stratification of the air layer prevailing throughout the day. The year-to-year comparison of minimums in the winter months reveals an average annual increase of the carbon dioxide content of 6 ppm/year, which is much greater than 1.5 ppm/year observed in the troposphere over Japan [1]. This indicates that the carbon dioxide concentration and its variations at Shibukawa station represent the local scale values rather than the large scale one. The horizontal distribution of carbon dioxide concentration, measured over sea surface near Shibukawa station, also suggests the existence of many patches of high concentration of carbon dioxide due to the local point sources related to the human activity such as ships and industries distributed at the coast site.

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Variationen des atmosphärischen CO₂ bei Shibukawa im Küstengebiet des Inlandsees Seto in Japan

Zusammenfassung Es werden Ergebnisse über Tages- und Jahresgänge von vierjährigen Messungen (1980–83) des CO₂ bei Shibukawa an der nördlichen Küste des Sees vorgelegt. Die Amplitude des Tagesganges beträgt in der kalten Jahreszeit ungefähr 30 ppm und in der warmen Jahreszeit ungefähr 60 ppm. Im Jahresgang des täglichen Minimums des CO₂ fällt das Maximum auf den Sommer und das Minimum auf Wintermonate. Dies entspricht nicht der aus der Aktvität der Vegetation zu erwartenden Variation. Das Sommermaximum scheint eine Besonderheit der Lage von Shibukawa an der Küste zu sein und ist wahrscheinlich auf die zu geringe vertikale Durchmischung bei der tagsüber dort vorherrschenden stabilen Schichtung zurückzuführen. Der Vergleich der Minima der Wintermonate von Jahr zu Jahr läßt eine Zunahme um 6 ppm pro Jahr erkennen, die bedeutend größer ist als die Zunahme um 1,5 ppm pro Jahr in der Troposphäre über Japan [ 1 ]. Dies weist darauf hin, daß die CO₂-Konzentration und ihre Variationen in Shibukawa eher lokale als großräumige Werte darstellen.Die über der Seeoberfläche in der Nähe von Shibukawa gemessene Verteilung der CO₂-Konzentrationen zeigt viele Stellen mit hoher CO₂-Konzentration, die auf lokale Punktquellen menschlicher Aktivität wie auf Schiffe und auf an der Küste verteilte Industrien hinweisen.

     

Concentrations of atmospheric constituents observed at Alert,Canada, in relation to air trajectories and synoptic systems

A meteorological analysis is presented for environmental data set obtained from the Canadian Arctic haze study, which is part of AGASP-II. Results of the study indicated that atmospheric carbon dioxide (CO₂), methane (CH₄), sulphate (SO₄ ⁼), ozone (O₃) and other air pollutants observed at Alert, N.W.T. underwent periodical fluctuations. It was found that high concentrations of these atmospheric constituents were associated with a deep (1430–2074 m) inversion and with a major anticyclone. In contrast, relatively low values of these constituents were associated with a cyclonic disturbance near Alert. High concentrations of these constituents occurred with air trajectories coming from the N-W direction, while low values occurred with S trajectories. In addition, examinations of satellite imagery with other meteorological data suggested that volcanic inputs of ash and gases from Augustine Island, Alaska were negligible for the observed high values of these constituents at the ground level at Alert.