1,721,076 research outputs found
Measurements of pCO2 and turbulence from an autonomous drifting buoy in 2019 during FALKOR cruise FK191120
No full textData from autonomous, drifting buoy with a floating chamber to measure insitu air-sea carbon dioxide (CO2) fluxes during RV Falkor cruise FK191120 in the southern Pacific during November-December 2019. The technique is described in detail in Ribas-Ribas et al. (2018) (https://doi.org/10.1525/elementa.275). The buoy is equipped with a sensor to measure aqueous and atmospheric partial pressure of CO2 (pCO2), and to monitor the increase or loss of CO2 inside the chamber. One complete cycle including two chamber measurements last 70 minutes. The buoy can be deployed for more than 15 hours, and at wind speeds of up to 10 m/s. Floating chambers are known to overestimate fluxes due to the creation of additional turbulence at the water surface. We check that by measuring turbulence with two Acoustic Doppler Velocimeter (ADV), one directly underneath the center of the floating chamber (equipped with an inertial motion unit) and the other one positioned sideways to measure turbulence outside the perimeter of the buoy
Seasonal distribution of the inorganic carbon system and net ecosystem production in the north eastern shelf of the Gulf of Cádiz (Southwest Iberian Peninsula)
No full textThere is scatter information of the inorganic carbon system in the coastal zones and it is important to increment our knowledge and understand the global carbon cycle. We investigated the distribution of inorganic carbon system parameters and its controls in the coastal waters of the north eastern shelf of the Gulf of Cádiz (GoC) during four cruises that took place in June 2006, November 2006, February 2007 and May 2007. The objectives of this study are: (1) to describe the spatio-temporal distribution of inorganic carbon system parameters in waters of the north eastern shelf of the GoC using four cruises, each undertaken in one of the four seasons, (2) to calculate net ecosystem production (NEP) and (3) to examine factors controlling these distributions. The distribution of inorganic carbon system parameters in the north eastern shelf of the Gulf of Cádiz showed temporal and spatial variability. River input, mixing, primary production, respiration, CO2 air–sea exchange, and remineralization were factors that controlled such distributions. The coastal zone of the GoC is autotrophic on an annual scale at a rate of 1.0 mmol m?2 d?1. Further measurements are needed it to improve the NEP calculation and to evaluated to intra-annual variability
Spatio-temporal variability of the dissolved organic carbon and nitrogen in a coastal area affected by river input: The north eastern shelf of the Gulf of Cádiz (SW Iberian Peninsula)
No full textFour surveys (June and November 2006; February and May 2007) were carried out in the north eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to investigate the dynamics of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in a coastal area affected mainly by river input, but also by primary production/respiration, resuspension from the sediments, and mixing. In the period of the present study, DOC values ranged from 42 to 198 ?M, while DON ranged from 0 to 20 ?M. The seasonal variations showed high mean surface concentrations of DOC (106.2 ± 25.6 ?M-C) and DON (8.6 ± 3.1 ?M-N) in May, shifting to low DOC (89.1 ± 26.4 ?M-C) and DON (4.2 ± 2.8 ?M-N) in February. In spring, DOC and DON released by phytoplankton are likely to be the most significant source of organic matter. Low DOC and DON concentrations during winter are probably due to the uptake of DOC and DON by bacteria and to the strong mixing of the water column. The spatial variations showed the highest mean concentrations of dissolved organic matter (DOM) in the lower part of the Guadalquivir Estuary and the lowest mean concentrations of DOM in the bottom water of the oceanic zone. The very high mean DOC and DON concentrations measured off the Guadalquivir Estuary may be due to river input and/or re-suspension of the organic matter from the bottom sediments. The very low mean DOC and DON concentrations measured in the bottom water of the continental shelf may be due to mineralization and a surplus of more refractory organic carbon
Measurements of pCO2 and turbulence from an autonomous drifting buoy in 2016 during FALKOR cruise FK161010
No full textTurbulence and pCO2 data from autonomous, drifting buoy with a floating chamber that will allow us to calculate air-sea CO2 fluxes and gas transfer velocities (k) with high temporal and spatial resolution. The buoy is equipped with a sensor to measure aqueous and atmospheric pCO2, and to monitor the increase or loss of CO2 inside the chamber. A complete cycle lasts 40 minutes, and after flushing the chamber a new cycle is initiated. The buoy has been described in [1] and can be deployed for more than 12 hours, and at wind speeds of up to 8 m s-1. Floating chambers are known to overestimate fluxes due to the creation of additional turbulence at the water surface. We correct fluxes by measuring turbulence with two Acoustic Doppler Velocimeter: one directly underneath the center of the floating chamber, that was an Inertial motion unit (IMU) to correct for the own movement of the buoy and the other one positioned sideways to measure turbulence outside the perimeter of the buoy
Air–sea CO2 fluxes in the north-eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula)
No full textAn intra-annual investigation of the fugacity of CO2 (fCO2) has been conducted in surface waters of the north-eastern shelf of the Gulf of Cádiz (SW Iberian Peninsula) in four cruises made in 2006 and 2007. Intra-annual variability of fCO2 was assessed and is discussed in terms of mixing, temperature and biology. In the study area of the shelf, thermodynamic control over fCO2 predominates from early May to late November, and this is opposite and similar in magnitude to the net biological effect. However, biological control over fCO2 predominates during winter. The results suggest that surface waters in the coastal area are under-saturated with respect to atmospheric CO2 during most of the year; therefore they represent a sink for atmospheric CO2 between November and May (? 1.0 mmol m? 2 day? 1), but a weak source in June (1.3 mmol m? 2 day? 1). In contrast, the coastal ecosystems studied (the lower estuary of Guadalquivir Estuary and Bay of Cádiz) acted as a weak sink for atmospheric CO2 during February (? 1.3 mmol m? 2 day? 1) and as a source between May and November (2.6 mmol m? 2 day? 1). The resulting mean annual CO2 flux in the north-eastern shelf of the Gulf of Cádiz was ? 0.07 mol m? 2 year? 1 (? 0.2 mmol m? 2 day? 1), indicating that the area acts as a net sink on an annual basis
pCO2 and turbulence data from an autonomous drifting buoy in 2016 during FALKOR cruise FK161010
No full textMeasurements of turbulence from an autonomous drifting buoy in 2019 during FALKOR cruise FK191120
No full textData from autonomous, drifting buoy with a floating chamber to measure insitu air-sea carbon dioxide (CO2) fluxes during RV Falkor cruise FK191120 in the southern Pacific during November-December 2019. The technique is described in detail in Ribas-Ribas et al. (2018) (https://doi.org/10.1525/elementa.275). The buoy is equipped with a sensor to measure aqueous and atmospheric partial pressure of CO2 (pCO2), and to monitor the increase or loss of CO2 inside the chamber. One complete cycle including two chamber measurements last 70 minutes. The buoy can be deployed for more than 15 hours, and at wind speeds of up to 10 m/s. Floating chambers are known to overestimate fluxes due to the creation of additional turbulence at the water surface. We check that by measuring turbulence with two Acoustic Doppler Velocimeter (ADV), one directly underneath the center of the floating chamber (equipped with an inertial motion unit) and the other one positioned sideways to measure turbulence outside the perimeter of the buoy
Measurements of pCO2 from an autonomous drifting buoy in 2019 during FALKOR cruise FK191120, station 2
No full textData from autonomous, drifting buoy with a floating chamber to measure insitu air-sea carbon dioxide (CO2) fluxes during RV Falkor cruise FK191120 in the southern Pacific during November-December 2019. The technique is described in detail in Ribas-Ribas et al. (2018) (https://doi.org/10.1525/elementa.275). The buoy is equipped with a sensor to measure aqueous and atmospheric partial pressure of CO2 (pCO2), and to monitor the increase or loss of CO2 inside the chamber. One complete cycle including two chamber measurements last 70 minutes. The buoy can be deployed for more than 15 hours, and at wind speeds of up to 10 m/s. Floating chambers are known to overestimate fluxes due to the creation of additional turbulence at the water surface. We check that by measuring turbulence with two Acoustic Doppler Velocimeter (ADV), one directly underneath the center of the floating chamber (equipped with an inertial motion unit) and the other one positioned sideways to measure turbulence outside the perimeter of the buoy
Measurements of sea surface temperature and salinity in a large seawater basin under varying precipitation intensities and droplet characteristics
No full textWe provide data from experiments with artificial rain over a 5100-liter basin with a retractable roof, where temperature and conductivity (to calculate salinity) were measured at different depths in the upper sea surface, as well as rain properties (intensity, rain temperature, droplet size and velocity). Three different nozzle types were used to investigate the impacts of droplet properties on temperature and salinity anomalies at the sea surface. To measure droplet sizes and velocities, we made calibration measurements with an optical laser disdrometer before the actual experiments. In the first experiments, we excluded external influences such as wind-driven mixing to show on a very small vertical and horizontal scale how very different rainfall intensities and properties such as droplet sizes and velocities affect sea surface temperature and salinity. In a second series of experiments, we used different stages of a flow pump to add turbulence to the basin and find out how quickly the rain water mixes with the seawater at the near-surface layer. The duration of the artificial rain was 15 minutes for all experiments. We used an acoustic doppler velocimeter (ADV) to calculate turbulent kinetic energy at two different depths (14 and 44 cm) within the basin. Additional samples from the sea surface microlayer (SML) were collected before and after the artificial rain in both experiments
Picophytoplankton and carbon cycle on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula)
Full text linkFour surveys (Jun’06 and Nov’06; Feb’07 and May’07) were carried out on the northeastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to relate the spatio-temporal distribution of the carbon cycle parameters (dissolved inorganic carbon and dissolved organic carbon) to picophytoplankton biomass and community composition. In addition, the net ecosystem production and the picophytoplankton contribution to the air-sea CO2 exchange process were investigated. The results showed that chlorophyll-a, carbon cycle parameters and picophytoplankton composition showed large seasonality, and the Guadalquivir Estuary plays an important role in the contribution of nutrient and suspended particular material over the year. Regarding picophytoplankton composition, the flow cytometry analysis demonstrated that Prochlorococcus and Synechococcus were the main populations in the studied area and their temporal and spatial distributions were complementary: the Prochlorococcus population showed its maximum concentration in May’07 and Jun’06 and in the surface oceanic water, whereas the Synechococcus population was at its maximum during Feb’07 and Nov’06, and off the Guadalquivir Estuary and Bay of Cádiz. In addition, a relationship between the studied parameters and the fugacity of CO2 was also observed, suggesting that primary production is an important factor in the regulation of this parameter in the studied area. The calculated carbon budget showed that the area acts as a carbon sink on an annual basis
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