Natural Versus Anthropogenic Factors Affecting Low-Level Cloud Albedo over the North Atlantic

Falkowski, Paul G.; Kim, Yong-Seung; Kolber, Zbigniew; Wilson, Cara; Wirick, Creighton D.; Cess, R. D.

doi:10.1126/science.256.5061.1311

Cited by 91 publications

(32 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increased light scattering and cloud cover would exert a cooling effect on the climate, thereby counteracting the warming trend. The existence of this 'global thermostat ' has not yet been confirmed, but there is evidence to support a relationship between DMS-derived sulfate aerosols and climatic events (Falkowski et al 1992, Legrand 1997, Clarke et al 1998.…”

Section: Introductionmentioning

confidence: 99%

Production and consumption of dimethylsulfide (DMS) in North Atlantic waters

Scarratt¹,

Levasseur²,

Schultes³

et al. 2000

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Production and consumption of dimethylsulfide (DMS) were studied in surface waters of the northwest Atlantic between latitude 32°and 45°N during May 1998. The kinetics of DMS production by the whole planktonic community were studied in short-term (3 h) experiments using additions of dissolved dimethylsulfoniopropionate (DMSP d ) (0 to 3000 nM). Measurements of DMS production and DMSP d consumption showed that the DMS production rate increased in direct proportion to the concentration of added DMSP d . This rate relationship did not saturate, suggesting acclimation of the microbial community to DMSP d concentrations much higher than the average for bulk seawater. Longer-term experiments were performed in which DMSP d consumption and DMS production were measured over 48 to 60 h. The DMSP d consumption rate decreased as the concentration of DMSP d decreased during the incubations. However, the DMS production rate was initially constant for the first 36 h. When DMSP d concentrations fell below 50 nM, DMS production stopped, even though DMSP d consumption continued. A possible explanation is that DMSP cleavage might dominate the total DMSP consumption at high DMSP d concentrations while DMSP demethylation and other processes dominate at low DMSP d concentrations. DMS consumption was measured both directly and by using the DMS consumption inhibitors dimethyl disulfide (DMDS) and methyl butyl ether (MBE). DMS consumption was generally undetectable except at 1 station dominated by a dense population of the DMSP-producing phytoplankton Chrysochromulina sp. and where ambient DMS concentrations were high. This suggests that the potential for DMS consumption is highest where ambient DMS levels are elevated. Pooling results from these experiments with earlier results from more northerly waters revealed an inverse exponential relationship (r 2 = 0.75, p < 0.0001) between the potential rate constant and chlorophyll a standing stock across a wide area of the Northwest Atlantic. This finding is potentially useful for the development of DMS production models.

show abstract

Section: Introductionmentioning

confidence: 99%

Production and consumption of dimethylsulfide (DMS) in North Atlantic waters

Scarratt¹,

Levasseur²,

Schultes³

et al. 2000

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…These aerosols can have direct effects by absorbing and reflecting incoming solar radiation (Mitchell et al 1995). They can also have indirect effects by acting as cloud condensation nuclei, thereby changing the microphysical properties of clouds, in particular increasing their albedo (Falkowski et al 1992;Clarke et al 1998). Consequently, DMS emissions may have a cooling effect on climate that partly counteracts the warming effect of greenhouse gases.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of the ocean DMS(P) pools in the Sargasso Sea viewed in a coupled physical-biogeochemical ocean model

Clainche¹,

Levasseur²,

Vézina³

et al. 2004

Can. J. Fish. Aquat. Sci.

View full text Add to dashboard Cite

Abstract:The dimethylsulfide (DMS) production model NODEM (Northern Oceans DMS Emission Model) was coupled with the water column ocean model GOTM (General Ocean Turbulence Model) that includes a two-equation k-ε turbulence scheme. This coupled physical-biogeochemical ocean model represents a significant improvement over the previous uncoupled version of NODEM that was driven by a diagnostic vertical mixing scheme. Using the same set of biogeochemical parameters, the coupled model is used to simulate the annual cycles of 1992 and 1993 at Hydrostation S in the Sargasso Sea. The better reproduction of the turbulent mixing environment corrects some deficiencies in nitrogen cycling, especially in the seasonal evolution of the nutrient concentrations. Hence, the coupled model captures the late-winter chlorophyll-and DMS(P)-rich blooms. It is also more adept at reproducing the vertical distribution of chlorophyll and DMS(P) in summer. Moreover, the DMS pool becomes less dependent on parameters controlling the nitrogen cycle and relatively more sensitive to parameters related to the sulfur cycle. Finally, the coupled model reproduces some of the observed differences in DMS(P) pools between 1992 and 1993, the latter being an independent data set not used in calibrating the initial version of NODEM.Résumé : Le modèle NODEM (« Northern Oceans DMS Emission Model ») de production de dimethylsulfide (DMS) a été couplé avec le modèle 1-D d'océan GOTM (« General Ocean Turbulence Model »), qui inclue un schéma de la turbulence océanique du second ordre de type k-ε. Ce modèle couplé physique et biogéochimique constitue une amé-lioration significative de la précédente version non couplée de NODEM, qui s'appuyait sur un schéma diagnostique pour le mélange vertical. Reprenant les mêmes paramètres biogéochimiques, le modèle couplé a été utilizé pour simuler le cycle saisonnier des années 1992 et 1993 à la station S en mer des Sargasses. La meilleure prise en compte de l'aspect turbulent du mélange océanique corrige certains défauts dans la représentation du cycle de l'azote, en particulier l'évolution saisonnière des concentrations en nutriments. Le modèle couplé capture maintenant les floraisons phytoplanctoniques de fin d'hiver et les pics en chlorophylle et en DMS(P) qui les caractérisent. Il améliore également la représentation des distributions verticales de chlorophylle et de DMS(P) en été. De plus, le réservoir de DMS est moins dépendant des paramètres contrôlant le cycle de l'azote, et relativement plus sensible aux paramètres reliés au cycle du souffre. Finalement, le modèle couplé reproduit certaines des différences observées entre 1992 et 1993 dans les réservoirs de DMS(P), la dernière année constituant un jeu de données indépendant qui n'a pas été utilizé pour la calibration de la version initiale de NODEM.Le Clainche et al. 803

show abstract

“…Because of the role of sulfate aerosols in both direct and indirect climate forcing, the biogeochemical cycling of DMS has been studied extensively for several decades (e.g., Charlson et al, 1987;Fogelqvist, 1991;Falkowski et al, 1992;Bates et al, 1992;Andreae and Crutzen, 1997;Gabric et al, 2004). Gas transfer at the sea-air interface links the DMS biogeochemical cycle in the surface ocean to atmospheric aerosol production and cloud physics.…”

Section: Introductionmentioning

confidence: 99%

Determining the sea-air flux of dimethylsulfide by eddy correlation using mass spectrometry

et al. 2010

View full text Add to dashboard Cite

Abstract. Mass spectrometric measurement of DMS by atmospheric pressure ionization with an isotopically labeled standard (APIMS-ILS) is a sensitive method with sufficient bandpass for direct flux measurements by eddy correlation. Use of an isotopically labeled internal standard greatly reduces instrumental drift, improving accuracy and precision. APIMS-ILS has been used in several recent campaigns to study ocean-atmosphere gas transfer and the chemical budget of DMS in the marine boundary layer. This paper provides a comprehensive description of the method and errors associated with DMS flux measurement from ship platforms. The APIMS-ILS instrument used by most groups today has a sensitivity of 100-200 counts s −1 pptv −1 , which is shown to be more than sufficient for flux measurement by eddy covariance. Mass spectral backgrounds (blanks) are determined by stripping DMS from ambient air with gold. The instrument is found to exhibit some high frequency signal loss, with a half-power frequency of ≈1 Hz, but a correction based on an empirically determined instrument response function is presented. Standard micrometeorological assumptions of steady state and horizontal uniformity are found to be appropriate for DMS flux measurement, but rapid changes in mean DMS mixing ratio may serve as a warning that measured flux does not represent the true surface flux. In addition, bias in surface flux estimates arising from the flux divergence is not generally significant in the surface layer, but under conditions of lowered inversion and high flux may become so. The effects of error in motion corrections and of vertical motion within the surface layer concentration gradient are discussed and the estimated maximum error from these effects is ≤18%.

show abstract

Natural Versus Anthropogenic Factors Affecting Low-Level Cloud Albedo over the North Atlantic

Cited by 91 publications

References 14 publications

Production and consumption of dimethylsulfide (DMS) in North Atlantic waters

Production and consumption of dimethylsulfide (DMS) in North Atlantic waters

Behaviour of the ocean DMS(P) pools in the Sargasso Sea viewed in a coupled physical-biogeochemical ocean model

Determining the sea-air flux of dimethylsulfide by eddy correlation using mass spectrometry

Contact Info

Product

Resources

About