Simulating indirect effects that thunderstorm activity has on atmospheric temperature

A coupled chemistry-climate model of both lower and middle atmospheres is used to study variations in the temperature of the atmosphere when its chemical composition is disturbed due to thunderstorm activity, which results in variations in its local heating and cooling and in atmospheric heat and mass transfer. The results of model calculations showed that, due to variations in the lightning production of nitrogen oxides and resulting variations in the concentrations of atmospheric gases, the temperature varies mostly in the lower and middle stratospheres over both tropical and polar regions. On average, over a period of several decades, this effect quantitatively amounts to a few tenths of a degree; however, it can reach a few degrees at heights of the lower stratosphere over Polar regions. The level of the statistical significance of estimates exceeds 0.95 almost within all height ranges for the global lightning production (exceeding 6 TgN/year).     

Simulation of the indirect impact that the 11-year solar cycle has on the gas composition of the atmosphere

An interactive three-dimensional chemistry-climate model combining models of the gas composition and general circulation of the lower and middle atmosphere is used to study the impact of changes in extra-atmospheric solar radiative fluxes induced by solar activity on the stratospheric heating and subsequent temperature and ozone variations in the stratosphere and troposphere. The results have shown that a change in the atmospheric radiative heating resulting from variations in solar activity has a direct effect on the temperature and circulation of the atmosphere. Atmospheric temperature variations affect the rates of temperature-dependent chemical reactions, and this is considered the first type of indirect impact of solar activity on the atmospheric gas composition. On the other hand, as a result of the variation in atmospheric heating, its circulation changes, thus affecting the transport of minor gases into the atmosphere. This effect is considered the second type of indirect impact of solar activity on atmospheric gases. The results of our calculations have shown that both types of indirect impact of the variation in solar activity on the atmospheric gas composition are comparable in order of magnitude to the direct impact of solar activity on atmospheric gases.     

Prognostic estimations of the atmospheric ozone content in the first half of the 21st century

New prognostic estimates are obtained for the potential variability of the atmospheric ozone content in the first half of the 21st century. The calculations are based on models of gas composition and general circulation in the lower and middle atmosphere and on the scenarios of the World Meteorological Organization (WMO). It is shown that the rate of ozone content increase will be controlled to a considerable extent by variations in stratospheric temperature. Even though the contents of atmospheric chlorine and bromine are not reduced, contrary to the WMO prediction, and remain at the present-day levels, the continuation of stratospheric cooling will lead to a rapid recovery of the ozone content to its level characteristic of the 1980s. Model experiments on variations in the stratospheric aerosol content have shown that an increase in the aerosol concentration will not affect the rate of ozone recovery in the atmosphere during reduced emissions of chlorine and bromine gases if the stratospheric temperature remains lowered. Numerical experiments have also shown that the simultaneous anthropogenic action on the contents of halogen gases and on the lower-stratosphere temperature can reduce the adverse effects of Freons and halons on the ozone layer.     

Analysis of the sensitivity of the composition and temperature of the stratosphere to the variability of spectral solar radiation fluxes induced by the 11-year cycle of solar activity

The sensitivity of the gas composition of the atmosphere and its temperature to the changes in spectral radiation fluxes during the 11-year cycle of solar activity has been analyzed with a chemistry-climate model of the lower and middle atmosphere. For this, the data of satellite measurements acquired in the first decade of the 21st century were used. The results of the model calculations showed that, in addition to the increase in the spectral flux in the absorption bands of molecular oxygen that leads to the growth of the ozone content, the changes in the flux at longer wavelengths are significant for the composition and temperature of the atmosphere. The changes of the ozone destruction rate in different catalytic cycles partly compensate each other; in these processes, the destruction rate increases in the reaction with atomic oxygen, while it decreases in the hydrogen and chlorine cycles.     

Transient Atmospheric Events Measured by Detectors on the Vernov Satellite

In this paper, data obtained by the Vernov satellite are discussed in comparison with the data obtained by Universitetsky–Tatiana-1, 2 satellites. The advanced instrumentation onboard the Vernov satellite improved the capabilities of the data-transmission system, providing an opportunity to acquire more detailed information on transient atmospheric events (TAEs), including a wider range of TAE photon numbers (event brightness) down to lower photon numbers, the opportunity to observe the events in ultraviolet range without the considerable inclusion of red–infrared photons (which indicates the substantial contribution of electric discharges, lightning precursors, at the altitudes of thunderstorm clouds), and the observation of TAE series at a rate of about 10–100 occurrences per second with a period from tens of seconds to several minutes.     

Combined chemistry-climate model of the atmosphere

A combined three-dimensional global model of the chemistry and dynamics of the lower and middle atmosphere (up to 90 km from the Earth’s surface) is described. With the use of this model within the AMIP2 (1979–1995) program, numerical calculations were performed with consideration for the interactive coupling between the ozone content, radiation heating, and atmospheric circulation. Comparisons were made between calculated and observed data on the ozone content and temperature. Heterogeneous processes on the surface of polar stratospheric clouds were shown to be important for a correct simulation of the spatial and temporal distribution of atmospheric ozone.     

Simulation of changes in global ozone and atmospheric dynamics in the 21st century with the chemistry-climate model SOCOL

The solar climate ozone links (SOCOL) three-dimensional chemistry-climate model is used to estimate changes in the ozone and atmospheric dynamics over the 21st century. With this model, four numerical time-slice experiments were conducted for 1980, 2000, 2050, and 2100 conditions. Boundary conditions for sea-surface temperatures, sea-ice parameters, and concentrations of greenhouse and ozone-depleting gases were set following the IPCC A1B scenario and the WMO A1 scenario. From the model results, a statistically significant cooling of the model stratosphere was obtained to be 4–5 K for 2000–2050 and 3–5 K for 2050–2100. The temperature of the lower atmosphere increases by 2–3 K over the 21st century. Tropospheric heating significantly enhances the activity of planetary-scale waves at the tropopause. As a result, the Eliassen-Palm flux divergence considerable increases in the middle and upper stratosphere. The intensity of zonal circulation decreases and the meridional residual circulation increases, especially in the winter-spring period of each hemisphere. These dynamic changes, along with a decrease in the concentrations of ozone-depleting gases, result in a faster growth of O₃ outside the tropics. For example, by 2050, the total ozone in the middle and high latitudes approaches its model level of 1980 and the ozone hole in Antarctica fills up. The superrecovery of the model ozone layer in the middle and high latitudes of both hemispheres occurs in 2100. The tropical ozone layer recovers far less slowly, reaching a 1980 level only by 2100.     

Variations in the chemical composition of the atmosphere from satellite measurements and their relation to fluxes of energetic particles of cosmic origin (Review)

New information about the chemical composition of the stratosphere and mesosphere is reviewed. This information was obtained in different seasons in both hemispheres with the use of the MIPAS (IR limb sounder), Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY; UV-visible and near-IR nadir and limb viewer), and Global Ozone Mapping Spectrometer (GOMOS) instruments installed on the European Envisat satellite launched in 2002. Measurements with the MIPAS instrument make it possible to retrieve information about the composition of the nighttime atmosphere. It should be noted that several powerful solar proton events (SPEs) occurred on the Sun in the period of satellite measurements. As is well known, the ionization of the polar atmosphere by SPEs is responsible for the intense interaction between ionic and neutral constituents below 100 km, which leads to the additional formation of nitrogen oxides and OH radicals destroying the ozone. Therefore, observations of the composition of the middle atmosphere in these periods are of great interest, because such situations serve as a unique test which makes it possible to check our knowledge not only about photochemical processes in the atmosphere but also about its interaction with cosmic plasma. The results of a comparison of model calculations with newly obtained data on the chemical composition, including those for SPE periods, are presented.     

A model of the impact of solar proton events on the ionic and gaseous composition of the mesosphere

A one-dimensional ionic-photochemical model of the gaseous composition of the atmosphere that describes the formation of the D layer of the ionosphere is presented. Based on this model, the vertical profiles of the concentration of electrons and ions in the D layer of the ionosphere were calculated, as were the vertical distributions of minor gaseous constituents in the atmosphere up to a height of 86 km for undisturbed conditions and after a powerful solar proton events (SPE) at the end of October 2003. The calculations showed that SPEs significantly increase NO_x in the mesosphere of polar latitudes. In the lower mesosphere of polar caps, the NO_x mixing ratio increases by 20–50 ppb; in the upper mesosphere it increases by 100 ppb and more. High NO_x levels in zones of their formation can be retained for several weeks, producing a long-term but comparatively small ozone decrease in the lower mesosphere. The main ozone decrease is caused by a short-term HO_x increase after SPEs and is also of a short-term character in the conditions of the illuminated mesosphere. After the SPE in October 2003, model calculations yield an ozone concentration decrease by 40% in the middle and upper mesosphere at 75 ° S and by 70% at the same heights at 70 ° N. The results of modeling NO_x and O₃ changes after the SPE in October 2003 agree well with the data of satellite measurements. The changes in minor gases of the mesosphere after the SPE obtained in the model with parameterized sources of HO_x and NO_x are compared with their changes obtained in the complete ionic-photochemical model. The changes in HO_x, NO_x, and O₃ coincide rather well, whereas the changes in ClO noticeably differ, especially in the lower mesosphere. Thus, at a height of about 60 km, the parameterized photochemical model underestimated twofold the ClO formation after the SPE.     

海洋中生源活性气体的来源与迁移转化

海洋生源活性气体主要包括二甲基硫（DMS）、甲烷（CH₄）、氧化亚氮（N₂O）、一氧化碳（CO）、挥发性卤代烃（VHCs）和非甲烷烃（NMHCs）等。它们通过海-气交换进入大气，不仅在全球碳、氮和硫循环中发挥关键作用，而且会直接或间接地对环境和气候变化产生重要影响。海洋释放的活性气体一类属于温室效应气体（CH₄、N₂O、VHCs和CO等），另一类会在大气中发生化学反应，控制着大气氧化平衡和臭氧浓度（VHCs和NMHCs）。而DMS属于负温室效应气体，其在大气中被快速氧化形成硫酸盐气溶胶，进而对云的形成和辐射强迫产生重要影响。本文综述了国内外海洋生源活性气体的研究现状，着重介绍了DMS、CH₄和N₂O的来源、迁移转化、海-气通量及其影响机制，并指明了该领域存在的科学问题及今后的研究方向。     

Comparing data obtained from ground-based measurements of the total contents of O<Subscript>3</Subscript>, HNO<Subscript>3</Subscript>,HCl,and NO<Subscript>2</Subscript> and from their numerical simulation

Chemistry climate models of the gas composition of the atmosphere make it possible to simulate both space and time variations in atmospheric trace-gas components (TGCs) and predict their changes. Both verification and improvement of such models on the basis of a comparison with experimental data are of great importance. Data obtained from the 2009–2012 ground-based spectrometric measurements of the total contents (TCs) of a number of TGCs (ozone, HNO₃, HCl, and NO₂) in the atmosphere over the St. Petersburg region (Petergof station, St. Petersburg State University) have been compared to analogous EMAC model data. Both daily and monthly means of their TCs for this period have been analyzed in detail. The seasonal dependences of the TCs of the gases under study are shown to be adequately reproduced by the EMAC model. At the same time, a number of disagreements (including systematic ones) have been revealed between model and measurement data. Thus, for example, the EMAC model underestimates the TCs of NO₂, HCl, and HNO₃, when compared to measurement data, on average, by 14, 22, and 35%, respectively. However, the TC of ozone is overestimated by the EMAC model (on average, by 12%) when compared to measurement data. In order to reveal the reasons for such disagreements between simulated and measured data on the TCs of TGCs, it is necessary to continue studies on comparisons of the contents of TGCs in different atmospheric layers.     

Dynamics of surface-air pollution during the passage of a cold front

The dynamics of meteorological parameters, of sodar data on the temperature stratification of the atmospheric boundary layer, and of surface contents of pollutants (nitrogen oxides, carbon monoxide, and ozone) during the passage over Moscow of a structurally complex prominent cold front are discussed. It is shown that the cold front passage is accompanied by stepwise increases in the NO, NO₂, and CO surface contents. A probable cause of this phenomenon is a quick entrainment of smoke plumes from high-altitude sources of pollution into the surface turbulent air near the frontal boundary. Intense advection of cold air at the rear of the cyclone can lead to the development of an unstable stratification in the atmospheric boundary layer even in the nighttime. Under these conditions, the minute-scale variability of contents of trace gases increases abruptly as compared to that occurring in the frontal zone of the cyclone prior to the passage of the front. This effect is statistically significant. The dynamics of surface ozone reflects an increase in its background concentrations in arctic air masses.     

Seasonal variation of average phytoplankton concentration in the Kattegat—a periodical point model

Seasonal variations in primary production, phytoplankton biomass, chlorophyll-a, dissolved inorganic phosphorus and nitrogen concentrations in the upper 10 m of the Kattegat were analysed by means of monitoring data from 1993–1997. Spatial optimal analysis, based on a stochastic model, was used to reconstruct weekly constituent fields onto a spatial grid. The reconstructed fields were spatially integrated, resulting in a relatively smooth seasonal variability of the average variables. A simple dynamical model, set up as a periodical boundary problem, is suggested for the average phytoplankton concentration, dissolved inorganic nitrogen and entrainment depth as state variables. The model is forced by the solar radiation, nitrogen load from the land sources and atmosphere as well as by nitrogen supply from the lower nutrient-rich layer. The latter process is modelled proportional to the water entrainment into the upper euphotic layer and is driven by atmospheric forcing, river runoff and the Baltic water inflow. Four model coefficient values were fitted by minimising the root mean square difference between the integrated monitoring data and the model output. The suggested diagnostic model reflects the main features in seasonal variability of phytoplankton and nitrogen concentrations by average values, including the magnitude and timing of such dynamic events as the spring and late summer phytoplankton blooms. The importance of different forcing factors is quantified and estimates of unobserved components such as new primary production can be computed.     

Variations in gaseous pollutants in the air basin of Moscow

Variations in the concentrations of gaseous pollutants in the air basin of Moscow are statistically analyzed. The basic statistical characteristics of variations in the concentrations of carbon monoxide, nitric oxide, nitrogen dioxide, ozone, formaldehyde, and a number of aromatic compounds are calculated. The main properties of intradiurnal, synoptic, seasonal, and interannual variations in the concentrations of gaseous pollutants are described. The power spectral densities of variations in the concentrations of carbon monoxide and nitrogen oxides are analyzed. The contributions made by variations in the concentration of carbon monoxide on different time scales to the total variance are calculated. The effect of the atmospheric air polluted with carbon monoxide and nitrogen oxides on the ecological situation in the city is estimated. The probabilities of an excess over the single maximum allowable concentrations are determined for carbon monoxide and nitrogen oxides. The absorption of shortwave solar radiation by nitrogen dioxide in the atmospheric boundary layer is estimated.     

Numerical simulation of the response of general circulation of the middle atmosphere to spatial inhomogeneities of orographic waves

We have developed a parameterization of the dynamical and thermal effects of stationary orographic waves (SOWs) generated by the earth’s surface topography and included it into the general circulation model of the middle and upper atmosphere. We have analyzed the sensitivity of atmospheric general circulation at tropospheric to thermospheric altitudes to the impact of SOWs propagating from the troposphere. Changes in atmospheric circulation due to variations in the SOW generation and propagation have been considered for different seasons. It has been shown that, during solstices, the main dynamical and thermal impacts the middle atmosphere of winter hemispheres, where the SOW-induced changes in the velocity of zonal circulation can reach 30%. During equinoxes, the SOW impact is distributed more homogeneously between the Northern and Southern hemispheres, and the relative changes in the velocity of zonal circulation of the middle atmosphere may constitute 10%.     

Modeling the convective cloudiness and its impact on the atmospheric gaseous composition

A combined three-dimensional numerical model of convective cloudiness with detailed microphysics and a model of the transport of atmospheric trace gases with gas- and aqueous-phase chemistry were developed. We consider the main physical mechanisms responsible for the formation of midsized droplet clouds and the transport of gases with differing solubility therein. Test numerical calculations were performed to investigate the sensitivity of the cloud model to variations in input parameters, as well as the variability of the ion composition of cloud drops with regard to their size distribution. The results of numerical calculations are presented with a preliminary analysis.     

Potential rates and environmental controls of denitrification and nitrous oxide production in a temperate urbanized estuary

Denitrification may play a major role in inorganic nitrogen removal from estuarine ecosystems, particularly in those subjected to increased nitrate and organic matter loads. The Douro estuary (NW Portugal) suffers from both problems: freshwater input of nitrate and organic load from untreated wastewater discharges. To assess how these factors might control sediment denitrification, a 12-month survey was designed. Denitrification potential and nitrous oxide (N₂O) production were measured at different locations using the slurry acetylene blockage technique. Denitrification rate ranged from 0.4 to 38 nmol N g⁻¹ h⁻¹, increasing towards the river mouth following an urban pollution gradient. N₂O production, a powerful greenhouse gas implicated on the destruction of the ozone layer, was significantly related with sediment organic matter and accounted for 0.5–47% of the N gases produced. Additional enrichment experiments were consistent with the results found in the environment, showing that sediments from the upper less urban stretch of the estuary, mostly sandy, respond positively to carbon and, inversely, in organic rich sediments from the lower estuary, the denitrification potential was limited by nitrate availability. The obtained results confirmed denitrification as an important process for the removal of nitrate in estuaries. The presence of wastewater discharges appears to stimulate nitrogen removal but also the production of N₂O, a powerful greenhouse gas, exacerbating the N₂O:N₂ ratio and thus should be controlled.     

The concentration and distribution of dimethyl sulfide in the marine atmospheric boundary layer near the equator

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Atmospheric temperature sounding with the Fourier spectrometer

Preliminary results of a space experiment using the IKFS-2 infrared sounder (Meteor-M2 satellite) showed high-quality of measurements of spectra of the outgoing thermal radiation of the atmosphere–surface system and the adequacy of developed IR radiation atmospheric models in the 15-μm carbon gas absorption band used to recover the vertical profiles of the atmospheric temperature. Outgoing radiation spectra measured by IKFS-2 instruments make it possible to restore vertical temperature profiles with errors close to 1K in most of the 0–30 km high-altitude region, except for the lower troposphere and altitudes above 30 km, where these errors are close to 2–3K.     

Dynamics of trace gases and aerosols in the atmosphere with consideration for heterogeneous processes

A combined mathematical model has been developed to reproduce space and time variations in the concentrations of multicomponent gas constituents and aerosols in the atmosphere on both regional and urban scales. This model contains blocks of transport of gas constituents and aerosols in the atmosphere with consideration for homogeneous binary nucleation, the kinetic processes of condensation/evaporation and coagulation, chemical processes occurring in both gas and liquid phases, and the processes of mass exchange during the gas-droplet (particle) interaction. A nonhydrostatic model of atmospheric mesoscale processes is used to calculate the fields of meteorological elements and turbulent characteristics. The generation of new-phase particles from precursor gases by the mechanism of homogeneous binary nucleation and their interaction with background aerosol are considered. The results of numerical experiments are compared with the data obtained from field observations of both space and time variations in the concentrations of gas constituents and aerosols and in the ionic content of aerosol particles over the Baikal region under the influence of emissions from powerful industrial sources.