Acoustic energy transfer to the upper atmosphere from sinusoidal sources and a role of nonlinear processes

In the framework of solving the problem of acoustic energy transfer from near-surface sources through the upper atmosphere, the propagation of sinusoidal signals of different origin is studied. All calculations are made by means of a model that takes into account the inhomogeneity of the atmosphere, nonlinear effects, absorption, divergence of wave front due to long-range acoustic wave propagation, etc., but does not include the effect of gravity. Infrasonic waves of various periods and their absorption at various heights of the atmosphere are investigated. The calculations show that a sinusoidal signal is destroyed by nonlinear processes during its upward propagation; it transforms into two, initial and final, impulses. The location of the “transformation zone” depends on frequency; its height increases with decreasing frequency. The acoustic waves can heat the upper atmosphere, for example, waves with a period of 3 min generated by thunderstorms can heat the atmosphere by up to ΔT_a=13.08 K/day in the region of 323–431 km. The efficiency of a point artificial emitter is too weak to heat the atmosphere significantly.     

Use of coupled ozone fields in a 3-D circulation model of the middle atmosphere

With a detailed chemistry scheme for the middle atmosphere up to 70 km which has been added to the 3-D Karlsruhe simulation model of the middle atmosphere (KASIMA), the effects of coupling chemistry and dynamics through ozone are studied for the middle atmosphere. An uncoupled version using an ozone climatology for determining heating rates and a coupled version using on-line ozone are compared in a 10-month integration with meteorological analyses for the winter 1992/93 as the lower boundary condition. Both versions simulate the meteorological situation satisfactorily, but exhibit a too cold lower stratosphere. The on-line ozone differs from the climatological data between 20 and 40 km by exhibiting too high ozone values, whereas in the lower mesosphere the ozone values are too low. The coupled model version is stable and differs only above 40 km significantly from the uncoupled version. Direct heating effects are identified to cause most of the differences. The well-known negative correlation between temperature and ozone is reproduced in the model. As a result, the coupled version slightly approaches the climatological ozone field. Further feedback effects are studied by using the on-line ozone field as a basis for an artificial climatology. For non-disturbed ozone conditions realistic monthly and zonally averaged ozone data are sufficient to determine the heating rates for modelling the middle atmosphere.     

Surface ozone in the aretic atmosphere

Near-surface atmospheric ozone measurements were carried out at Barrow, Alaska (71°, 19N, 156°W), from January 1965 to September 1967. Ozone was continuously monitored by microcoulombmetric analysis at a level 2 m above the ground. Daily ozone concentrations near the ground varied from 7 to less than 1 pphm by volume. Highest concentrations occurred in the spring and showed sharp increases lasting from several hours to a few days. These sudden rises in ozone concentration correlated with storm front passages. The concentration of surface ozone from late spring through the sumer and fall showed less variability from day to day than in the spring. The lowest ozone concentrations occurred from late May to early June.     

The importance of energetic particle precipitation on the chemical composition of the middle atmosphere

An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O₃ is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O₃ is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O₃. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O₃ depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.     

The radiative energy budget of the middle atmosphere and its parameterization in general circulation models

The thermal regime of the middle atmosphere is determined to a great extent by the balance between the incoming solar and outgoing infrared radiation. To account for these processes in numerical models of the middle atmosphere, parameterizations that are capable of quickly and accurately calculating infrared cooling and solar heating rates are required. These parameterizations should include the breakdown of local thermodynamic equilibrium (LTE) conditions and allow for feedbacks by ensuring that dependencies on all input parameters are accounted for. This paper discusses the major mechanisms responsible for maintaining the radiative energy budget of the middle atmosphere and presents a brief review of approaches and numerical schemes currently available for use in general circulation models. The main focus of the paper is on the approaches and schemes designed for non-LTE treatment.     

A review of gravity wave saturation processes,effects, and variability in the middle atmosphere

This paper provides a review of our current understanding of the processes responsible for gravity wave saturation as well as the principal effects and variability of saturation in the lower and middle atmosphere. We discuss the theoretical and observational evidence for linear and nonlinear saturation processes and examine the consequences of saturation for wave amplitude limits, momentum and energy fluxes, the diffusion of heat and constituents, and the establishment of a near-universal vertical wavenumber spectrum. Recent studies of gravity wave variability are reviewed and are seen to provide insights into the significant causes of wave variability throughout the atmosphere.     

Variations of the total amount of ozone and the behaviour of some ionospheric parameters in the winter time upper atmosphere

Pure and Applied Geophysics -     

Synoptic-scale fluctuations of total ozone in the atmosphere

A model, based on ozone-concentration tendency equation, is developed to study synoptic ozone-column variations. The application is referred to a middle-latitude site and to an atmospheric layer extending from the surface up to about 35-km altitude. Photochemical effects at the considered location for synoptic time scales are considered negligible. The data input consists of umkehr ozone profile, total ozone (obtained by Brewer No. 067, located at Rome) and horizontal wind at various levels. Analysis of several cases indicates that meridional advection is the main factor responsible for the observed synoptic-scale ozone fluctuations.     

Numerical simulation of the influence of stationary mesoscale orographic waves on the meridional circulation and ozone fluxes in the middle atmosphere

The authors’ parameterization of the dynamic and thermal action of stationary orographic waves generated by the Earth’s surface relief is included into the model of general circulation of the middle and upper atmosphere. Numerical simulation of the general circulation in the troposphere and stratosphere was performed and the influence of stationary orographic waves propagating upward from the Earth’s surface on the meridional and vertical velocity was studied. It is shown that the allowance for the dynamic and thermal action of these waves in the numerical model leads to changes by up to 20–30% in the meridional circulation and ozone fluxes associated with it at heights of the ozone layer maximum.     

Optical measurement in the middle atmosphere

The various measurement techniques and general problems in remote orin situ optical measurement of atmospheric minor gases are described.     

The early history of oxygen and ozone in the atmosphere

There may have been three stages in the growth of oxygen in the terrestrial atmosphere. Prior to the origin of photosynthesis the only source of oxygen was photolysis of water vapor followed by escape of hydrogen to space. The rate of this process was probably less than the rate of release of reduced gases (principally hydrogen) from volcanoes, so the oxygen partial pressure was held to negligibly low values by photochemical reactions with an excess of hydrogen. The photosynthetic source of oxygen was probably in operation as long ago as 3.8 billion years. It released oxygen to the ocean. Presumably most of this oxygen was destroyed in the ocean as long as its rate of supply was less than the rate of supply of readily oxidizable material (principally Fe²⁺) provided by the weathering of rocks. This phase appears to have lasted until about 2 billion years ago, during which period most banded iron formations were deposited. During this period the production of oxygen by algae was limited by competition with photosynthetic bacteria, which preempted the supply of nutrient phosphorus as long as reduced chemicals were available in the environment. Once the photosynthetic oxygen source exceeded the rate of supply of reduced minerals exposed by erosion and weathering, the accumulation of oxygen in the ocean and atmosphere could be controlled only by reaction of oxygen with reduced organic material. This is the stabilization mechanism that operates today. It seems unlikely that oxygen could be consumed at a significant rate by this process until oxygen levels sufficiently high to support respiration had been achieved. I therefore suggest that atmospheric oxygen rose rapidly from essentially zero to approximately its present value (within a factor of 10) when the photosynthetic source of oxygen rose above the weathering source of reduced minerals, probably about 2 billion years ago. The ozone layer and the ultraviolet screen were absent prior to this time and essentially fully developed after this time.Presented at IAGA/IAMAP Symposium on Minor Neutral Constituents in Middle Atmosphere-Chemistry and Transport, Seattle, August, 1977.     

Impact of different energies of precipitating particles on NOx generation in the middle and upper atmosphere during geomagnetic storms

Energetic particle precipitation couples the solar wind to the Earth's atmosphere and indirectly to Earth's climate. Ionisation and dissociation increases, due to particle precipitation, create odd nitrogen (NO_x) and odd hydrogen (HO_X) in the upper atmosphere, which can affect ozone chemistry. The long-lived NO_x can be transported downwards into the stratosphere, particularly during the polar winter. Thus, the impact of NO_x is determined by both the initial ionisation production, which is a function of the particle flux and energy spectrum, as well as transport rates. In this paper, we use the Sodankylä Ion and Neurtal Chemistry (SIC) model to simulate the production of NO_x from examples of the most representative particle flux and energy spectra available today of solar proton events (SPE), auroral energy electrons, and relativistic electron precipitation (REP). Large SPEs are found to produce higher initial NO_x concentrations than long-lived REP events, which themselves produce higher initial NO_x levels than auroral electron precipitation. Only REP microburst events were found to be insignificant in terms of generating NO_x. We show that the Global Ozone Monitoring by Occultation of Stars (GOMOS) observations from the Arctic winter 2003–2004 are consistent with NO_x generation by a combination of SPE, auroral altitude precipitation, and long-lived REP events.     

Model studies of the influence of O2 photodissociation parameterizations in the Schumann-Runge bands on ozone related photolysis in the upper atmosphere

A new parameterization for atmospheric transmission and O₂ photodissociation in the Schumann-Runge band region has been developed and tested with a 1D radiative-photochemical model. The parameterization is based on the O₂-column along the line of sight to the Sun and the local temperature. Line-by-line calculations have served as a benchmark for testing this method and several other, commonly used, parameterizations. The comparisons suggest that differences between the line-by-line calculations and currently accepted parameterizations can be reduced significantly by using the new method, particularly at large solar zenith angles. The production rate of O-atoms computed with this method shows less than 6% deviation compared to the line-by-line calculations at any altitude, all solar zenith angles and in all seasons. The largest errors are found toward the shorter wavelengths in the Schumann-Runge region at low altitudes. Transmittance is approximated to better than 4% at any altitude and/or solar zenith angle. The total O-production rate above 20 km is approximated to better than 2%. The new parameterization is easily implemented in existing photochemical models and in many cases it may simply replace the existing algorithm. The computational effort exceeds that of other parameterizations but in view of the total computation time needed for the actual calculation of the parameterized Schumann-Runge bands this should not lead to significant performance degeneration. The first 14 coefficients of the parameterization are included in this study. Both the complete sets of coefficients and a simple algorithm can be obtained by contacting the authors. A photochemical model study shows the largest effect of the parameterization method is on odd hydrogen concentrations. Subsequent interaction with an odd oxygen family causes differences in the ozone concentrations between the different parameterizations of more than 10% at selected altitudes. Although it is already established that deficiencies in the treatment of Schumann-Runge band absorption are unlikely to explain the current underestimation of ozone concentration at the stratopause in a variety of photochemical models, this study does show that the choice of parameterization has a large impact on the accuracy of the results at large solar zenith angles and in different seasons.     

Modeling of nonmigrating tides in the middle atmosphere

On the basis of calculations using the general circulation model of the middle and upper atmosphere, the relative role of sources of nonmigrating tides distributed in atmosphere has been investigated. It is shown that in winter, when planetary waves in stratosphere are well developed, the main contribution to the generation of nonmigrating tides is caused by nonlinear interaction between migrating tides and a quasi-stationary planetary wave with zonal wave number 1 (SPW1). Taking into account the longitudinal ozone inhomogeneities in the model leads to the occurrence of additional sources of nonmigrating tides caused by longitudinally inhomogeneous heating of the atmosphere, the contribution of which can be comparable to that from nonlinear interaction under an attenuating amplitude of SPW1 in the stratosphere.     

Nonlinear internal waves in the upper atmosphere

To investigate the mechanism of mixing in oscillatory doubly diffusive (ODD) convection, we truncate the horizontal modal expansion of the Boussinesq equations to obtain a simplified model of the process. In the astrophysically interesting case with low Prandtl number (traditionally called semiconvection), large-scale shears are generated as in ordinary thermal convection. The interplay between the shear and the oscillatory convection produces intermittent overturning of the fluid with significant mixing. By contrast, in the parameter regime appropriate to sea water, large-scale flows are not generated by the convection. However, if such flows are imposed externally, intermittent overturning with enhanced mixing is observed.     

Instrumentation for measuring and recording mass and energy transfer from volcanoes to atmosphere

A new approach to the understanding of volcanic activity is attempted. It consists in establishing tentative correlations between all measurable physical, chemical and geophysical eruptive parameters. The first stage of this program is to devise and design gauges and recorders of different types to be used on different types of existing eruptive vents, whatever their shape, size, violence and accessibility. The methods adopted and the first results obtained on the physical parameters of eruptive gases are described here.     

Trends in planetary wave activity in the upper middle atmosphere inferred from the nighttime LF radio wave absorption measurements

Summary The nighttime LF radio wave absorption in the lower ionosphere measured at two frequencies in central Europe over 1963–1985 is used to infer planetary wave activity and its long-term trend in the upper middle atmosphere (∼90–100 km). The observed positive trend is roughly consistent with results based on daytime absorption. Nighttime results are less pronounced and less statistically significant probably due to perturbing effects of geomagnetic activity. The observed trends, which are probably of anthropogenic origin, are together with the daytime results [3,4] the first evidence of long-term trends in planetary wave activity in the upper middle atmosphere.     

An investigation of the dependence of structural parameters of the middle atmosphere on the intensity of photochemical and dynamical processes

Using a numerical model for temperature and neutral and ion composition behaviour at middle atmospheric heights, an analysis has been made of the dependence of atmospheric structural parameters on temperature, solar activity, and on turbulent transfer intensity. For mesospheric heights, an inverse dependence of the nitric oxide density on the temperature has been found. It is thus possible to explain experimentally obtained temperature variations over a cyclc of solar activity at mesospheric and lower thermospheric heights. Numerical simulation results indicate that the temperature in the height range 75–120 km depends considerably on both the absolute values of turbulent transfer coefficients and their vertical gradients.     

An investigation on the relationship between high energy charged particle flux in the upper atmosphere and the earthquake activities

This paper presents the analytic result on the correlation between the high energy charged particle flux in the radiation belt around the earth and the earthquake activities. It points out that the increment of count-speed of high energy charged particle flux in the upper atmosphere has definite relationship with the intensity of seismic activities on the earth. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 100–103, 1992.     

Planetary waves in coupling the lower and upper atmosphere

The purpose of the paper is to answer the question if planetary waves (PW) are capable of propagating into the thermosphere. First the simplest vertical structure equation of the classic tidal theory accounting for a realistic vertical temperature profile is considered. Analysis and simulation show that the well-known normal atmospheric modes (NM), which are trapped in the lower and middle atmosphere, exhibit a wave-like vertical structure with a large vertical wavelength in the thermosphere. Moreover, the reflection of these modes from the vertical temperature gradient in the lower thermosphere causes appearance of the wave-energy upward flux in the middle atmosphere, and in a linearized formulation this flux is constant above the source region. To investigate a possibility of the NM forcing by stratospheric vacillations and to consider the propagation of different PW up to the heights of the upper thermosphere, a set of runs with a mechanistic Middle and Upper Atmosphere Model has been performed. The results of the simulation show that quasi-stationary and longer-period PW are not able to penetrate into the thermosphere. The shorter-period NM and ultra-fast Kelvin wave propagate up to the heights of the lower thermosphere. However, above about 150 km they are strongly suppressed by dissipative processes. The role of the secondary waves (nonmigrating tides) arising from nonlinear interaction between the primary migrating tides and quasi-stationary PW is discussed. We conclude that PW are not capable of propagating directly up to the heights of the ionospheric F2 region. It is suggested that other physical processes (for instance, the electrostatic field perturbations) have to be taken into account to explain the observed PW-like structures in ionospheric parameters.