scholarly journals Deriving a sea surface climatology of CO<sub>2</sub> fugacity in support of air–sea gas flux studies

2014 ◽  
Vol 11 (4) ◽  
pp. 1895-1948 ◽  
Author(s):  
L. M. Goddijn-Murphy ◽  
D. K. Woolf ◽  
P. E. Land ◽  
J. D. Shutler ◽  
C. Donlon
Keyword(s):  
Co2 Flux ◽  
Co2 Concentration ◽  
Sea Surface ◽  
Climate Variables ◽  
Gas Flux ◽  
Concentration Difference ◽  
Surface Measurements ◽  
Thermodynamic Driving Force ◽  
Ocean Carbon ◽  
Carbon Dioxide Co2

Abstract. Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean Carbon Dioxide (CO2) Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. fCO2 is highly sensitive to temperature and the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrent with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air–sea CO2 fluxes it is therefore desirable to calculate fCO2 valid for climate quality SST. This paper presents a method for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using climate quality SST data from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air–sea CO2 flux, and hence the presented fCO2 distributions can be used in air–sea gas flux calculations together with climatologies of other climate variables.

scholarly journals The OceanFlux Greenhouse Gases methodology for deriving a sea surface climatology of CO<sub>2</sub> fugacity in support of air–sea gas flux studies

Ocean Science ◽  
2015 ◽  
Vol 11 (4) ◽  
pp. 519-541 ◽  
Author(s):  
L. M. Goddijn-Murphy ◽  
D. K. Woolf ◽  
P. E. Land ◽  
J. D. Shutler ◽  
C. Donlon
Keyword(s):  
Greenhouse Gases ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Sea Surface ◽  
Prediction Errors ◽  
Climate Variables ◽  
Gas Flux ◽  
Concentration Difference ◽  
Surface Measurements ◽  
Thermodynamic Driving Force

Abstract. Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean CO2 Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. As fCO2 is highly sensitive to temperature, the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrently with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air–sea CO2 fluxes, it is therefore desirable to calculate fCO2 valid for a more consistent and averaged SST. This paper presents the OceanFlux Greenhouse Gases methodology for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using monthly composite SST data on a 1° × 1° grid from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010, including the prediction errors of fCO2 produced by the spatial interpolation technique. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air–sea CO2 flux, and hence the presented fCO2 distributions can be used in air–sea gas flux calculations together with climatologies of other climate variables.

Soil CO2 flux affected by Aporrectodea caliginosa earthworms

2010 ◽  
Vol 5 (3) ◽  
pp. 364-370 ◽  
Author(s):  
Miloslav Šimek ◽  
Václav Pižl
Keyword(s):  
Co2 Emissions ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Experimental Period ◽  
Aporrectodea Caliginosa ◽  
Soil Co2 Flux ◽  
Soil Air ◽  
Soil Microbial ◽  
Carbon Dioxide Co2 ◽  
Soil Accumulation

AbstractThe effects of Aporrectodea caliginosa earthworms on both carbon dioxide (CO2) accumulation in and emissions from soil, as well as the simultaneous impact of earthworms on soil microbiological properties were investigated in a microcosm experiment carried out over 5.5 months. Concentration of CO2 in soil air was greater at a depth of 15 cm when compared with a depth of 5 cm, but varied during the season both in control and earthworm-inhabited chambers. Peaks of CO2 concentrations at both depths occurred in both treatments during August, approximately 80 days after the experiment started. Generally, the presence of earthworms increased the CO2 concentration at 15-cm depth. Larger CO2 emissions were consistently recorded in conjunction with higher amounts of CO2 in soil air when chambers were inhabited by earthworms. The total CO2 emissions during the experimental period covering 161 days were estimated at 118 g CO2-C m−2 and 99 g CO2-C m−2 from chambers with and without earthworms respectively. Moreover, the presence of earthworms increased microbial biomass in the centre and at the bottom of chambers, and enhanced both dehydrogenase activity and nitrifying enzyme activity in the soils. We suggest that the effect of earthworms on both the enhanced soil accumulation of CO2 as well as emissions of CO2 was mostly indirect, due to the impacts of earthworms on soil microbial community.

scholarly journals Interannual sea–air CO<sub>2</sub> flux variability from an observation-driven ocean mixed-layer scheme

2014 ◽  
Vol 11 (17) ◽  
pp. 4599-4613 ◽  
Author(s):  
C. Rödenbeck ◽  
D. C. E. Bakker ◽  
N. Metzl ◽  
A. Olsen ◽  
C. Sabine ◽  
...  
Keyword(s):  
Southern Oscillation ◽  
Atmospheric Oxygen ◽  
Large Fraction ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Co2 Partial Pressure ◽  
Surface Ocean ◽  
The North ◽  
Ocean Carbon ◽  
Carbon Dioxide Co2

Abstract. Interannual anomalies in the sea–air carbon dioxide (CO2) exchange have been estimated from surface-ocean CO2 partial pressure measurements. Available data are sufficient to constrain these anomalies in large parts of the tropical and North Pacific and in the North Atlantic, in some areas covering the period from the mid 1980s to 2011. Global interannual variability is estimated as about 0.31 Pg C yr−1 (temporal standard deviation 1993–2008). The tropical Pacific accounts for a large fraction of this global variability, closely tied to El Niño–Southern Oscillation (ENSO). Anomalies occur more than 6 months later in the east than in the west. The estimated amplitude and ENSO response are roughly consistent with independent information from atmospheric oxygen data. This both supports the variability estimated from surface-ocean carbon data and demonstrates the potential of the atmospheric oxygen signal to constrain ocean biogeochemical processes. The ocean variability estimated from surface-ocean carbon data can be used to improve land CO2 flux estimates from atmospheric inversions.

scholarly journals Interannual sea–air CO<sub>2</sub> flux variability from an observation-driven ocean mixed-layer scheme

2014 ◽  
Vol 11 (2) ◽  
pp. 3167-3207 ◽  
Author(s):  
C. Rödenbeck ◽  
D. C. E. Bakker ◽  
N. Metzl ◽  
A. Olsen ◽  
C. Sabine ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Large Fraction ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Co2 Partial Pressure ◽  
Surface Ocean ◽  
Independent Information ◽  
Northern Pacific ◽  
Ocean Carbon ◽  
Carbon Dioxide Co2

Abstract. Interannual anomalies in the sea–air carbon dioxide (CO2) exchange have been estimated from surface-ocean CO2 partial pressure measurements. Available data are sufficient to constrain these anomalies in large parts of the tropical and Northern Pacific and in the Northern Atlantic, in some areas since the mid 1980s to 2011. Global interannual variability is estimated as about 0.31 Pg C yr−1 (temporal standard deviation 1993–2008). The tropical Pacific accounts for a large fraction of this global variability, closely tied to ENSO. Anomalies occur more than 6 months later in the East than in the West. The estimated amplitude and ENSO response are consistent with independent information from atmospheric oxygen data. Despite discrepancies in detail, this both supports the variability estimated from surface-ocean carbon data, and demonstrates the potential of the atmospheric oxygen signal to constrain ocean biogeochemical processes. The ocean variability estimated from surface-ocean carbon data can be used to improve land CO2 flux estimates from atmospheric inversions.

scholarly journals Measurements of CO<sub>2</sub> exchange with an automated chamber system throughout the year: challenges in measuring nighttime respiration on porous peat soil

2013 ◽  
Vol 10 (8) ◽  
pp. 14195-14238 ◽  
Author(s):  
M. Koskinen ◽  
K. Minkkinen ◽  
P. Ojanen ◽  
M. Kämäräinen ◽  
T. Laurila ◽  
...  
Keyword(s):  
Friction Velocity ◽  
Peat Soil ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Chamber System ◽  
Fitting Method ◽  
Starting Point ◽  
Best Fitting ◽  
Flux Estimation ◽  
Carbon Dioxide Co2

Abstract. We built an automatic chamber system to measure greehouse gas (GHG) exchange in forested peatland ecosystems. We aimed to build a system robust enough which would work throughout the year and could measure through a changing snowpackin addition to producing annual GHG fluxes by integrating the measurements without the need of using models. The system worked rather well throughout the year, but it was not service free. Gap filling of data was still necessary. We observed problems in carbon dioxide (CO2) flux estimation during calm summer nights, when a CO2 concentration gradient from soil/moss system to atmosphere builds up. Chambers greatly overestimated the nighttime respiration. This was due to the disturbance caused by the chamber to the soil-moss CO2 gradient and consequent initial pulse of CO2 to the chamber headspace. We tested different flux calculation and measurement methods to solve this problem. The estimated flux was strongly dependent on (1) the type of the fit (linear and polynomial), (2) the starting point of the fit after closing the chamber, (3) the length of the fit, (4) the speed of the fan mixing the air inside the chamber, and (5) atmospheric turbulence (friction velocity, u&amp;ast;). The best fitting method (the most robust, least random variation) was linear fitting with the period of 120–240 s after chamber closure. Furthermore, the fan should be adjusted to spin at minimum speed to avoid the pulse-effect, but it should be kept on to ensure mixing. If nighttime problems cannot be solved, emissions can be estimated using daytime data from opaque chambers.

scholarly journals Uncertainties in wind speed dependent CO<sub>2</sub> transfer velocities due to airflow distortion at anemometer sites on ships

2010 ◽  
Vol 10 (11) ◽  
pp. 5123-5133 ◽  
Author(s):  
F. Griessbaum ◽  
B. I. Moat ◽  
Y. Narita ◽  
M. J. Yelland ◽  
O. Klemm ◽  
...  
Keyword(s):  
Wind Speed ◽  
Three Dimensional ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Gas Transfer ◽  
Co2 Uptake ◽  
Flow Distortion ◽  
Simulation Code ◽  
Transfer Velocity ◽  
Concentration Difference

Abstract. Data from platforms, research vessels and merchant ships are used to estimate ocean CO2 uptake via parameterisations of the gas transfer velocity (k) and measurements of the difference between the partial pressures of CO2 in the ocean (pCO2 sw) and atmosphere (pCO2 atm) and of wind speed. Gas transfer velocities estimated using wind speed dependent parameterisations may be in error due to air flow distortion by the ship's hull and superstructure introducing biases into the measured wind speed. The effect of airflow distortion on estimates of the transfer velocity was examined by modelling the airflow around the three-dimensional geometries of the research vessels Hakuho Maru and Mirai, using the Large Eddy Simulation code GERRIS. For airflows within ±45° of the bow the maximum bias was +16%. For wind speed of 10 m s−1 to 15 m s−1, a +16% bias in wind speed would cause an overestimate in the calculated value of k of 30% to 50%, depending on which k parameterisation is used. This is due to the propagation of errors when using quadratic or cubic parameterisations. Recommendations for suitable anemometer locations on research vessels are given. The errors in transfer velocity may be much larger for typical merchant ships, as the anemometers are generally not as well-exposed as those on research vessels. Flow distortion may also introduce biases in the wind speed dependent k parameterisations themselves, since these are obtained by relating measurements of the CO2 flux to measurements of the wind speed and the CO2 concentration difference. To investigate this, flow distortion effects were estimated for three different platforms from which wind speed dependent parameterisations are published. The estimates ranged from −4% to +14% and showed that flow distortion may have a significant impact on wind speed dependent parameterisations. However, the wind biases are not large enough to explain the differences at high wind speeds in parameterisations which are based on eddy covariance and deliberate tracer methods.

scholarly journals The BrIdge voLcanic LIdar—BILLI: A Review of Data Collection and Processing Techniques in the Italian Most Hazardous Volcanic Areas

2020 ◽  
Vol 10 (18) ◽  
pp. 6402
Author(s):  
Stefano Parracino ◽  
Simone Santoro ◽  
Luca Fiorani ◽  
Marcello Nuvoli ◽  
Giovanni Maio ◽  
...  
Keyword(s):  
Data Collection ◽  
Co2 Flux ◽  
Volcanic Eruptions ◽  
Co2 Concentration ◽  
Volcanic Hazards ◽  
Volcanic Gases ◽  
Volcanic Gas ◽  
Mt Etna ◽  
Carbon Dioxide Co2 ◽  
Processing Techniques

Volcanologists have demonstrated that carbon dioxide (CO2) fluxes are precursors of volcanic eruptions. Controlling volcanic gases and, in particular, the CO2 flux, is technically challenging, but we can retrieve useful information from magmatic/geological process studies for the mitigation of volcanic hazards including air traffic security. Existing techniques used to probe volcanic gas fluxes have severe limitations such as the requirement of near-vent in situ measurements, which is unsafe for operators and deleterious for equipment. In order to overcome these limitations, a novel range-resolved DIAL-Lidar (Differential Absorption Light Detection and Ranging) has been developed as part of the ERC (European Research Council) Project “BRIDGE”, for sensitive, remote, and safe real-time CO2 observations. Here, we report on data collection, processing techniques, and the most significant findings of the experimental campaigns carried out at the most hazardous volcanic areas in Italy: Pozzuoli Solfatara (Phlegraen Fields), Stromboli, and Mt. Etna. The BrIdge voLcanic LIdar—BILLI has successfully obtained accurate measurements of in-plume CO2 concentration and flux. In addition, wind velocity has also been retrieved. It has been shown that the measurements of CO2 concentration performed by BILLI are comparable to those carried out by volcanologists with other standard techniques, heralding a new era in the observation of long-term volcanic gases.

scholarly journals A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink

2013 ◽  
Vol 10 (11) ◽  
pp. 7793-7815 ◽  
Author(s):  
P. Landschützer ◽  
N. Gruber ◽  
D. C. E. Bakker ◽  
U. Schuster ◽  
S. Nakaoka ◽  
...  
Keyword(s):  
Neural Network ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Carbon Sink ◽  
Co2 Flux ◽  
South Atlantic ◽  
Sea Surface ◽  
Series Data ◽  
Surface Ocean ◽  
Ocean Carbon

Abstract. The Atlantic Ocean is one of the most important sinks for atmospheric carbon dioxide (CO2), but this sink has been shown to vary substantially in time. Here we use surface ocean CO2 observations to estimate this sink and the temporal variability from 1998 through 2007 in the Atlantic Ocean. We benefit from (i) a continuous improvement of the observations, i.e. the Surface Ocean CO2 Atlas (SOCAT) v1.5 database and (ii) a newly developed technique to interpolate the observations in space and time. In particular, we use a two-step neural network approach to reconstruct basin-wide monthly maps of the sea surface partial pressure of CO2 (pCO2) at a resolution of 1° × 1°. From those, we compute the air–sea CO2 flux maps using a standard gas exchange parameterization and high-resolution wind speeds. The neural networks fit the observed pCO2 data with a root mean square error (RMSE) of about 10 μatm and with almost no bias. A check against independent time-series data and new data from SOCAT v2 reveals a larger RMSE of 22.8 μatm for the entire Atlantic Ocean, which decreases to 16.3 μatm for data south of 40° N. We estimate a decadal mean uptake flux of −0.45 ± 0.15 Pg C yr−1 for the Atlantic between 44° S and 79° N, representing the sum of a strong uptake north of 18° N (−0.39 ± 0.10 Pg C yr−1), outgassing in the tropics (18° S–18° N, 0.11 ± 0.07 Pg C yr−1), and uptake in the subtropical/temperate South Atlantic south of 18° S (−0.16 ± 0.06 Pg C yr−1), consistent with recent studies. The strongest seasonal variability of the CO2 flux occurs in the temperature-driven subtropical North Atlantic, with uptake in winter and outgassing in summer. The seasonal cycle is antiphased in the subpolar latitudes relative to the subtropics largely as a result of the biologically driven winter-to-summer drawdown of CO2. Over the 10 yr analysis period (1998 through 2007), sea surface pCO2 increased faster than that of the atmosphere in large areas poleward of 40° N, while in other regions of the North Atlantic the sea surface pCO2 increased at a slower rate, resulting in a barely changing Atlantic carbon sink north of the Equator (−0.01 ± 0.02 Pg C yr−1 decade−1). Surface ocean pCO2 increased at a slower rate relative to atmospheric CO2 over most of the Atlantic south of the Equator, leading to a substantial trend toward a stronger CO2 sink for the entire South Atlantic (−0.14 ± 0.02 Pg C yr−1 decade−1). In contrast to the 10 yr trends, the Atlantic Ocean carbon sink varies relatively little on inter-annual timescales (±0.04 Pg C yr−1; 1 σ).

scholarly journals Spatio-temporal variations of cave-air CO2 concentrations in two Croatian show caves: Natural vs. anthropogenic controls

2021 ◽  
Vol 74 (3) ◽  
pp. 273-286
Author(s):  
Maša Surić ◽  
◽  
Robert Lončarić ◽  
Matea Kulišić ◽  
Lukrecija Sršen ◽  
...  
Keyword(s):  
Co2 Flux ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Natural Processes ◽  
Air Temperatures ◽  
Show Caves ◽  
Spatio Temporal ◽  
Bora Wind ◽  
Carbon Dioxide Co2 ◽  
The Right

Carbon dioxide (CO2) concentration (CDC) plays an important role in karst processes, governing both carbonate deposition and dissolution, affecting not only natural processes, but also human activities in caves adapted for tourism. Its variations due to various controlling parameters was observed from 2017 to 2021 in two Croatian show caves (Manita peć and Modrič) where we examined inter- and within-cave correlation of internal aerology regarding the sources, sinks and transport mechanism of CDC in a karst conduit setting. In both caves, the main sources of CO2 are: i) plant and microbial activity i.e. root respiration and organic matter decay within soil horizons and fractured epikarst, and ii) degassing from CO2-rich percolation water. The main sink of CO2 is dilution with outside air due to cave ventilation. Chimney-effect driven ventilation controlled by seasonal differences between surface and cave air temperatures shows winter (Tout<Tcave) and summer (Tout>Tcave ) ventilation regime, which are modulated by the geometry of cave passages, the transmissivity of the overlying epikarst, and occasionally by the external winds, especially the gusty north-eastern bora wind. In these terms, the Modrič Cave appears to be more confined and less ventilated, with a substantial CDC difference between the left (550-7200 ppm) and right (1475- >10,000 ppm) passages. The Manita peć Cave is, in contrast, ventilated almost year-round, having 7 months of CDC equilibrated with the outside atmosphere and the highest summer CDC values of ~1410 ppm. In both caves, at the current level of tourist use, anthropogenic CO2 flux is not a matter of concern for cave conservation. In turn, in the innermost part of the right Modrič Cave passage visitors’ health might be compromised, but the tourists are allowed only in the left passage. Speleothem growth rate, recognized as a useful palaeoenvironmental proxy for speleothem-based palaeoclimate studies, strongly depends on CDC variations, so the high CDCs recorded in the Modrič Cave indicate the potential periods with no speleothem deposition due to the hampered degassing of CO2 from the dripping groundwater. The opposite effect i.e. enhanced ventilation (that supports calcite precipitation) during the windy glacials/stadials, as well as substantial vegetational changes must also be taken into consideration when interpreting environmental records from spelean calcite.

scholarly journals Thermal and haline effects on the calculation of air-sea CO<sub>2</sub> fluxes revisited

2012 ◽  
Vol 9 (11) ◽  
pp. 16381-16417 ◽  
Author(s):  
D. K. Woolf ◽  
P. E. Land ◽  
J. D. Shutler ◽  
L. M. Goddijn-Murphy
Keyword(s):  
Co2 Flux ◽  
Sea Surface ◽  
Recent Analysis ◽  
Upper Ocean ◽  
Saturated Vapour Pressure ◽  
Salinity Gradients ◽  
Interfacial Concentration ◽  
Carbon Dioxide Co2 ◽  
The Relationship ◽  
Opposing Effect

Abstract. The presence of vertical temperature and salinity gradients in the upper ocean and the occurrence of variations in temperature and salinity on time scales from hours to many years complicate the calculation of the flux of carbon dioxide (CO2) across the sea surface. Temperature and salinity affect the interfacial concentration of aqueous CO2 primarily through their effect on solubility with lesser effects related to saturated vapour pressure and the relationship between fugacity and partial pressure. The effects of temperature and salinity profiles and changes in the aqueous concentration act primarily through the partitioning of the carbonate system. Contrary to some recent analysis, it is shown that the effect on CO2 fluxes of a cool skin on the sea surface is large and ubiquitous. An opposing effect on calculated fluxes is related to the occurrence of warm layers near the surface; this effect can be locally large but will usually coincide with periods of low exchange. A salty skin and salinity anomalies in the upper ocean also affect CO2 flux calculations, though the haline effects are generally weaker than the thermal effects.

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