Marine Aerosol Concentrations Research Articles

Real-time single particle monitoring of a relative increase in marine aerosol concentration during winter rainstorms

Real-time single particle monitoring of a relative increase in marine aerosol concentration during winter rainstorms

Real‐time single particle monitoring of a relative increase in marine aerosol concentration during winter rainstorms

During the months of December 1996 and January 1997, aerosol characterization was performed in real‐time at Riverside, CA, an inland location approximately 100 km east of the Los Angeles coast. Analysis was performed on a single particle basis with measurements of both particle size and composition. Data were collected throughout the course of five rainstorms. Single particle mass spectra demonstrate that obvious composition changes occur in the aerosol systems as the marine air mass is transported inland. While precipitation scavenging of aerosols was observed, there was a significant relative increase of sea salt particles in the non‐scavenged aerosol. Compositionally‐resolved particle size distributions also demonstrate real‐time changes that occur in the atmospheric aerosol sample.

Dry deposition and concentration of marine aerosols in a coastal area, SW Sweden

The present paper introduces a model for the dry deposition of marine aerosols in a coastal area of SW Sweden. The model, incorporating wind speed and distance from shore, is based on repeated measurements of salt impingement on specially designed salt traps in dense profiles from the shore and inland. The measurements show that the deposited salts include two significantly different components, one dynamic containing large droplets, with short residence time in the air, deposited close to the shore, the other one being microscopic droplets, with long residence time in the air and with a low deposition velocity (principally, the system is similar to that of mineral particles, i.e. saltating dune sand vs loess). The deposition of marine aerosols has various effects on the terrestrial environments. Aside from those associated to human activities, i.e. technical effects on outdoor electrical installations, increased corrosion of cars, etc. there are others associated to natural ecosystems. Hence, salts are important contributors to major and trace elements for plant growth. On the other hand, the deposition of windborne salt spray is believed to form an important stress factor on forests and especially to exposed stands of Norway spruce ( Picea abies L.). In this latter sense it is the authors' opinion that the rising number of westerly gales reported on the Swedish west coast during the last two decades might give an important contribution to the increasing amounts of damage observed from coniferous forests in SW Sweden.

Marine aerosol concentrations and estimated fluxes over the sea

Marine aerosol concentrations and estimated fluxes over the sea

Marine aerosol concentrations and estimated fluxes over the sea

Marine aerosol concentrations and estimated fluxes over the sea

Marine aerosol concentrations and estimated fluxes over the sea

AbstractAerosol particulate fluxes, generated at the sea surface by the action of the wind, have been derived from a comprehensive series of measurements taken in the Outer Hebrides, off the west coast of Scotland. These observations cover wind speeds from essentially zero to values in excess of 30 m s−1, and show that the particle production, over the radius range from 1 to 25 μm, is very strongly dependent upon the prevailing wind speed, especially for the larger particles. These fluxes, estimated for a height of about 10 m above the ocean surface, may be approximated by an expression comprising the sum of two log‐normal distributions (in particle radius R) of the form: where the values of fI and R0i remain essentially unchanged with wind speed, but with the values of Ai being strongly dependent upon this parameter.Alternative formulations of the aerosol flux, based upon combining field observations of the dependence of whitecap coverage upon prevailing wind speed with estimates of aerosol production from laboratory‐simulated whitecaps, provide poorer approximations to the aerosol observations, especially at the higher wind speeds when a substantial spume‐drop contribution may be expected.

The effects of dimethylsulfide upon marine aerosol concentrations

A simplified dimethylsulfide (DMS) oxidation mechanism is used in a box model to predict the vapor source rates of the major sulfur-containing products, methanesulfonic acid and sulfuric acid, in the marine boundary layer. These vapor source rates drive an integral aerosol model that predicts gas-to-particle conversion of the acid species in the presence of water vapor. The effects of latitudinal variations in background hydroxyl radical concentrations, temperatures, and relative humidities upon the predicted aerosol number concentrations are presented, and the sensitivity of the predictions to uncertainties in aerosol model input parameters is discussed. The predictions support a dependence of marine aerosol concentrations on latitude, as noted in some observations. Realistic choices of aerosol model parameters yield number concentrations that are consistent with observed concentrations in remote marine areas.

Palaeoclimatic information from ice cores: the Vostok records

ABSTRACTIce deposits from Greenland and Antarctic ice sheets have stored over long periods of time information about the climate and environment of our planet. Attention will be focused on the 2083 m Vostok Antarctic ice core which represents a unusually long record (160 000 ka) due to the low accumulation rate (∼2 g cm−2a−1) and the rather uniform conditions of ice flow. This ice core provides a unique opportunity to obtain several palaeo-data such as temperature, accumulation (precipitation), aerosol loading, CO2 and trace gases over a full glacial-interglacial climatic cycle.The Vostok temperature, deduced from the interpretation of the deuterium content, and the CO2 records show a large 100 ka signal with a change of the order of 10°C and 70 ppmv respectively. The two records are closely correlated and both display shorter periodicities characteristic of the earth orbital parameters. CH4 concentrations also show variations from about 0·35 to about 0·65 ppmv linked with the glacial-interglacial warming. These features suggest a fundamental link between the climatic system and the carbon cycle and stress the role of radiatively active gases in climatic changes.The accumulation (precipitation) record appears to be governed by temperature with values during the coldest stages reduced by a factor of 2 with respect to the present rate. Ice deposited during these coldest stage is also characterised by high concentration of marine and terrestrial aerosols; these peaks probably reflect strengthened sources and meridional transport during full glacial conditions, linked to higher wind speed, more extensive arid areas on surrounding continent and a greater exposure of continental shelves.

Atmospheric Chemistry Changes Over The Last Climatic Cycle (180 000 Years) Inferred From The Vostok (Antarctica) Ice-Core Study

A 2 200 m-deep ice core from Vostok Station (East Antarctica) has been used for a comprehensive study of a series of ions (Na+ NH4 +, K+, H+, Ca2+, Mg2+, C1−, F−, NO3 − and SO4 2−) originating from impurities deposited over the whole last climatic cycle (180 000 years) as depicted from the isotopic composition of the ice. Concentration profiles confirm that both marine and terrestrial aerosol inputs were higher (up to five and 30 times the Holocene values respectively) during cold climatic conditions. Such large variations of marine and terrestrial aerosol concentrations measured in ice mainly reflect global (source strength and atmospheric transport efficiency) changes, and to a lesser extent local (deposition) changes. As opposed to these primary aerosols, secondary aerosols or gases (HNO3, HC1) exhibit more moderate variations. Finally, variations of other minor ions such as NH4 + provide information on the capacity of ammonia to neutralize the natural acidity of the past background atmosphere. Spectral analyses performed on our chemical profiles (200 samples) exhibit several specific periodicities (around 20 and 40 k year) close to the Earth's orbit tilt and precession frequencies which are discussed in terms of atmospheric response to climatic fluctuations.

Atmospheric Chemistry Changes Over The Last Climatic Cycle (180 000 Years) Inferred From The Vostok (Antarctica) Ice-Core Study

A 2 200 m-deep ice core from Vostok Station (East Antarctica) has been used for a comprehensive study of a series of ions (Na+ NH4+, K+, H+, Ca2+, Mg2+, C1−, F−, NO3− and SO42−) originating from impurities deposited over the whole last climatic cycle (180 000 years) as depicted from the isotopic composition of the ice.Concentration profiles confirm that both marine and terrestrial aerosol inputs were higher (up to five and 30 times the Holocene values respectively) during cold climatic conditions. Such large variations of marine and terrestrial aerosol concentrations measured in ice mainly reflect global (source strength and atmospheric transport efficiency) changes, and to a lesser extent local (deposition) changes.As opposed to these primary aerosols, secondary aerosols or gases (HNO3, HC1) exhibit more moderate variations. Finally, variations of other minor ions such as NH4+ provide information on the capacity of ammonia to neutralize the natural acidity of the past background atmosphere.Spectral analyses performed on our chemical profiles (200 samples) exhibit several specific periodicities (around 20 and 40 k year) close to the Earth's orbit tilt and precession frequencies which are discussed in terms of atmospheric response to climatic fluctuations.

Chlorine, Bromine AND Iodine in arctic aerosols

Weekly suspended particulate samples were collected at three stations in the Canadian Arctic between 1979 and 1984. The halogens, Cl, Br and I were determined, along with a comprehensive suite of elements and ions. As was previously observed in Alaska, Br was found to peak every year just after the Arctic dawn, reaching concentrations of two orders of magnitude greater than could be explained by marine, automotive and crustal sources. Chlorine concentration correlated closely with that of Na, indicating a marine origin. It was found to be strongly depleted relative to Na during periods of high sulphate concentration. Iodine was found to be enormously enriched relative to seawater by a factor of 1000 –10,000. The enrichment was least during the early winter when marine aerosol concentrations were at their highest. At locations remote from open oceans I concentrations exhibited two annual peaks, one in the spring, and one during the early autumn. No clear correlations with other parameters could be found for these peaks. At locations close to open ocean, concentrations were higher than at the inland sites and did not vary seasonally.

Application of a mixed-layer model to aerosols in the marine boundary layer

A mixed-layer model for the concentration and evolution of marine aerosols is presented. Theambient aerosol spectrum is divided into continental and sea-salt components and transformedto a reference saturation ratio. The temporal evolution of the aerosol spectrum is predicted fromrate equations that require specification of the mixed-layer depth. particle production at thesurface, and particle entrainment into the mixed layer from aloft. The model was tested against amarine data set obtained off Southern California during the CEWCOM-78 experiment. The testwas carried out with two different methods of obtaining the relevant meteorological and aerosolparameters: (i) actual measurements and (ii) dynamic boundary layer model prediction andparameterization. In the first case. the model reproduced the aerosol data within a factor of 1.5.while in the second case, the uncertainty factor was 2.0. In either case. the model only modestlyout-performs a much simpler model, which uses only local specification of the wi...

Application of a mixed-layer model to aerosols in the marine boundary layer

A mixed-layer model for the concentration and evolution of marine aerosols is presented. Theambient aerosol spectrum is divided into continental and sea-salt components and transformedto a reference saturation ratio. The temporal evolution of the aerosol spectrum is predicted fromrate equations that require specification of the mixed-layer depth. particle production at thesurface, and particle entrainment into the mixed layer from aloft. The model was tested against amarine data set obtained off Southern California during the CEWCOM-78 experiment. The testwas carried out with two different methods of obtaining the relevant meteorological and aerosolparameters: (i) actual measurements and (ii) dynamic boundary layer model prediction andparameterization. In the first case. the model reproduced the aerosol data within a factor of 1.5.while in the second case, the uncertainty factor was 2.0. In either case. the model only modestlyout-performs a much simpler model, which uses only local specification of the wi...

Observational results on the influence of stability on surface layer marine aerosol concentrations

Observational results on the influence of stability on surface layer marine aerosol concentrations