Near-water Atmospheric Layer Research Articles

Ship borne studies of the distribution of PAHs and PM10 in the near-water atmospheric layer of Lake Baikal in the summer of 2016-2017

This work discusses the results of shipborne studies concerning the spatial distribution of PAHs and aerosol particles in the near-water atmospheric layer of Lake Baikal in July 2016-2017. We observed high concentrations of polluting components near the local sourceson the coast of the lake as well as in smoke plumes from wildfires. The low PAH concentrations recorded in 2017in the absence of wildfires were comparable with those of 2002 and 2008. Using the backward trajectory models, we traced air mass movements from the pollution sources to the lake.

Non-monotonous dependence of the ocean surface drag coefficient on the hurricane wind speed due to the fragmentation of the ocean-atmosphere interface

Influence of the spray generation due to the fragmentation of the “bag-breakup” type on momentum exchange in the atmospheric boundary layer above the sea surface at hurricane winds was investigated on the basis of the analysis of the results of laboratory experiments. It was shown that aerodynamic drag is determined by the contribution of three factors: first, the drag of the “bag-breakup” canopies as obstacles; second, acceleration of the spray formed during fragmentation by the air flow; and the third factor is related to the stratification of the near-water atmospheric layer due to the presence of levitated water droplets. Combination of all three factors leads to a non-monotonous dependence of the aerodynamic drag coefficient on wind speed, which confirms the results of the field and laboratory measurements.

Comparative studies of optical and microphysical characteristics and chemical composition of aerosol over water basin of Caspian Sea in the 29th and 41st cruises of RV Rift

We perform a comparative analysis of the atmospheric aerosol characteristics obtained in the Caspian Sea onboard the RV Rift in November 2008 and in October 2012 in the near-water atmospheric layer and in the entire atmospheric depth. We studied the aerosol optical depth in the wavelength range of 0.3–2.14 μm and the columnar water vapor of the atmosphere; the particle number density and the particle size distribution in the diameter range of 0.3–20 μm; the mass concentration of fine aerosol and the mass concentration of absorbing aerosol, i.e., black carbon; and the chemical ion composition of the soluble part of aerosol and gas admixtures, namely, Cl−, SO 4 2− , NO 3 − , PO 4 3− , F−, HCO 3 − , Na+, NH 4 + , K+, Mg2+, Ca2+, H+, HCl, HNO3, SO2, and NH3.

Thermal interaction between near-water atmospheric layer and surface water layer on the northeastern shelf of the Black Sea

Thermal interaction between near-water atmospheric layer and surface water layer is considered within long-term, seasonal, synoptic, and mesoscale variability ranges from long-term air and water temperature measurement data. It is established that long-term mean monthly values of water temperature within annual cycle are greater than corresponding values of air temperature. Equations of relationships are obtained for long-term mean annual, mean seasonal, and mean monthly air and water temperature values.

Measurements of soot aerosol content in the near-water atmospheric layer in the southern and northern hemispheres

We present the results of mass soot concentration measurements in the near-water layer of the atmosphere during two cruises of the “Academic Fedorov” research vessel (from September 25 to October 23, 1998, on a route from St. Petersburg to Franz Joseph Land and from November 8, 1999, to April 30, 2000, on a route from St. Petersburg to Antarctica and the Southern Ocean [I’m not sure this exists.]), the 27th cruise of the “Academician Ioffe” research vessel (from April 6 to May 19, 2009, from Ushuaia (Tierra del Fuego) to Gdansk (Poland)), and at the Russian Antarctic Bellingshausen station (from December 20, 2001, to March 11, 2002). It is shown that the soot content in the atmosphere above the Arctic Ocean in October 1998 is comparable to that obtained at stationary stations in 1989–1992. The latitudinal dependence (less soot content with increases in latitude) is observed in the Southern Hemisphere. The average concentration of soot at Bellingshausen station and in the Southern Ocean is 19–28 ng/m3 and is comparable with the level of pollution at the foreign McMurdo and Ferraz stations.

The role of the ocean in pleistocene climate changes

659 It is traditionally thought that due to the great dif� ference in thermal capacities of the atmosphere (C at ) and ocean (C ос ), the surface layer of the ocean becomes adopted to rapidly changeable conditions in the nearwater atmospheric layer during short time periods and, in contrast, it takes substantially more time for the atmosphere to become adapted to the ocean. Indeed, let us describe the thermal interrela� tionships between the atmosphere and the ocean in general form: (1) where "rapid" time t is selected so that the thermal capacity of the atmosphere is a unit, while that of the ocean is Cос times higher. It is seen then that, on the "rapid" time scale, the oceanic temperature remains practically unchanged

Methane anomalies in the near-water atmospheric layer above the shelf of East Siberian Arctic shelf

Simultaneous measurements of methane in the nearwater atmospheric layer and in the surface water layer were carried out for the first time in a shallow-water region of the East Siberian shelf. It follows from the data obtained that the regions of anomalously high values of methane concentration in the air (up to 8 ppm) spatially coincide with the patches of anomalously high concentrations of methane dissolved in water (up to 5 · 10 2 nM). The analysis of possible sources allowed us to formulate a hypothesis that the genesis of the distinguished anomalies can may be related to the deep sources of methane anomalies. Deep sources of methane include modern methane and/or ancient methane accumulated in the deposits of natural gas and methane gas hydrates. During warm interglacial epochs, the high latitudes of the Northern Hemisphere deliver methane into the atmosphere maintaining methane concentrations in the Arctic atmosphere higher by 8‐10% than that in the Antarctica atmosphere. During cold glacier epochs, this gradient decreases to practically insignificant levels [1]. Land ecosystems are considered the main sources of methane in the arctic region. A special role belongs to wetlands and thermal karst sink lakes underlining yearround by non-freezing talics regions. The total contribution of such ecosystems in the global methane cycle is estimated at 27‐28% (140‐145 Tg, where 1 Tg = 10 12 g) [2]. It is known that the Barrow atmospheric monitoring station in Barrow (Alaska, United States) annually records increased concentrations of methane in the atmosphere. Their maximums are continue from the summer season to the autumnal‐winter interseasonal period, when the production of land Arctic ecosystems decreases gradually and terminates [3]. Hence, the source maintaining high methane emission in the autumn‐winter period should possess a potential related to the influence of the other factors that are endemic for the Arctic region. Thus far, the role of marine Arctic ecosystems as methane sources has been considered insignificant. At the same time, data in [4, 5] indicate that the role of the Arctic Ocean (AO) is significantly underestimated. For example, the total flux contribution of methane into the atmosphere from the shallow-water part of the shelf only in the Russian seas of to the arctic region can reach the values comparable with the contribution of all continental seas the World Ocean [4]. In our opinion, the East Siberian Arctic shelf should be considered with special attention.

Transformation of Short Waves in a Nonuniform Flow Field on the Ocean Surface. The Effect of Wind Growth Rate Modulation

We develop a model of transformation of the short surface wave spectrum in the presence of a nonuniform flow on a water surface, in which the modulation of wind-wave growth rate is taken into account. The model of a turbulent near-water atmospheric layer is used to calculate the modulated growth rate. In this model, turbulent stresses in the wind are described using a gradient approximation with model eddy viscosity specified with allowance for the known laboratory experiments. The examples of short-wave modulation in the presence of nonuniform flows on a water surface, originating from ripples and intense internal waves, are considered. It is shown that deformations of the wind-velocity profile and its long-wavelength perturbation due to the nonlinear interaction between the wind surface waves and the wind has a significant effects on the short-wave growth rate and its modulation. In the case of ripples, this deformation reduces to an increase in the roughness parameter of the wind-velocity profile and to a velocity-profile modulation with ripple period. The modulated growth rate is calculated within the framework of a quasi-linear model of surface-wave generation by a turbulent wind, in which the hypothesis of random phases of the wind-wave field is used. The amplitude and phase of the hydrodynamical modulation transfer function are calculated within the framework of the relaxation model. The calculation results are in reasonable agreement with the available experimental data. A model described by the combined Korteweg–de Vries equation is used to study a surface flow field generated by intense internal waves. The internal-wave parameters are takes from the results of the COPE experiment. We calculate the wind growth-rate dependences on the wave-train phase for the cases of downwind and upwind propagation of an internal wave. The calculation results agree qualitatively with experimental data.

Some regularities of the ozone distribution in the near-water atmospheric layer

The results of measurements of the ozone concentration obtained during the first cruise of the R/VVladimir Parshin close to the European Atlantic coast and in the adjacent seas are analysed. A sharp (four-fold) decrease in the ozone concentration off the coast along 50° N was found. This effect is associated with ozone absorption by the ocean, which is conditioned by the interaction of ozone with surface-active substances in the surface microlayer of seawater. This assumption is supported by the local decrease of the ozone concentration when approaching the coast, observed in the Black Sea several times. It is shown that the correlation between the ozone concentration and carbon monoxide above the ocean agrees with the regularity observed.

Radioactive isotopes of caesium in the waters and near-water atmospheric layer of the Black Sea

The concentrations of137Cs and134Cs were measured using the sorption method in the waters of the Black Sea during 1986–1987. An inhomogeneous character of the contamination of the surface waters in the Black Sea due to the Chernobyl disaster is shown. The subsequent migration and redistribution of caesium radionuclides in the various seasons of the year were studied. The amount of137Cs and134Cs in the upper 50 m layer was estimated. The results of measuring the concentration of caesium radionuclides in the near-water atmospheric layer over the Black Sea and Mediterranean Sea in 1986–1987 are also reported.