An approximate computation of infrared radiative fluxes in a cloudy atmosphere

A two-stream approximation is applied to the equation of infrared (IR) radiative transfer in order to compute the detailed structure of fluxes and cooling/heating rates in inhomogeneous, cloudy atmospheres. The spectrum between 4 and 400 m is split into 50 bands, and absorption of water vapour, uniformly mixed gases, ozone, water vapour polymers and water droplets are taken into account. Allowance is made for scattering by water droplets in the atmospheric window region (8–12.8 m) where the delta function approximation is used. The backward scattering coefficient is calculated from the asymmetry parameter by means of a new simple formula. The model is compared to other radiative transfer schemes and some applications are presented.     

On the regional climatic impact of contrails: microphysical and radiative properties of contrails and natural cirrus clouds

The impact of contrail-induced cirrus clouds on regional climate is estimated for mean atmospheric conditions of southern Germany in the months of July and October. This is done by use of a regionalized one-dimensional radiative convective model (RCM). The influence of an increased ice cloud cover is studied by comparing RCM results representing climatological values with a modified case. In order to study the sensitivity of this effect on the radiative characteristics of the ice cloud, two types of additional ice clouds were modelled: cirrus and contrails, the latter cloud type containing a higher number of smaller and less of the larger cloud particles. Ice cloud parameters are calculated on the basis of a particle size distribution which covers the range from 2 to 2000 m, taking into consideration recent measurements which show a remarkable amount of particles smaller than 20 m. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase in the order of 1K, ranging from 1.1 to 1.2K in July and from 0.8 to 0.9K in October depending on the radiative characteristics of the air-traffic-induced ice clouds. Modelling the current contrail cloud cover which is near 0.5% over Europe yields a surface temperature increase in the order of 0.05 K.     

A numerical test of two approximate solutions to the radiative transfer equation using the Elsasser scheme

In a recent paperCharlock, Herman andZdunkowski (1976) disagree on how best to apply the Radiative Transfer Equation (RTE) in the construction of Elsasser type radiation tables. The two proposed approximation solutions are analyzed and compared against a quasiexact solution. Infrared fluxes and cooling rates are calculated for part of the 6.3 m water vapor band for two model atmospheres. It is found that the Zdunkowski (Z) approximation yields more accurate downward fluxes, while the Charlock-Herman (CH) approximation, in general, results in more accurate upward fluxes. For the two model atmospheres studied the cooling rates for theZ approximation are usually of better quality than those due to the CH solution, unless the divergence of the net flux is extremely small.     

The solar and lunar effect of earthquake duration and distribution

Phase folding algorithms are conventionally used in periodicity analyses using X-ray astronomy pulsar. These allow for accurate identification of the cycle and phase characteristics of the physical parameters of the periodic variation. Although periodic variations in earthquake activity have long been studied, this paper is the first to apply the phase folding algorithm to the analysis of shallow (<70 km) seismic data for the period 1973–2010. The goal is to study the phase distribution characteristics of earthquake frequencies and we see a connection between earthquake occurrence and solar and lunar cycles. First, the rotation of the Sun may play a significant role in impacting on the occurrence time of earthquakes with magnitudes of less than 6.0. This may be especially pertinent for earthquakes with magnitudes between 5.0 and 6.0, when the modulation ratio reaches 12 %. The Moon’s gravity, which is generally thought to have the greatest influence on the global environment, may actually play less of a role on earthquake timing than the rotation of the Sun. Second, when we consider the world to be divided into 72 local regions based on latitude and longitude, we can see that there are more than a dozen regions with significant non-uniform distributions of earthquake occurrence time. In these regions, the ratio of χ ² to the number of degrees of freedom far exceeds five. As a result, we posit that some factors associated with the Sun–Earth–Moon relationship may trigger earthquake activity under certain temporal and spatial conditions.     

Instability of a thin magnetic tube in the solar atmosphere

Abstract

The static equilibrium of a thin vertical magnetic tube embedded in the solar atmosphere is shown to be dynamically unstable against the fundamental mode of perturbation having no nodes in the vertical displacement. The instability has its origin in the convection zone, and the eigenfunction is extended further up in the stable upper layers by the magnetic field which guides the displacement mainly in the longitudinal direction. It is suggested that the downdraft observed in the solar network structure is a finite amplitude consequence of this instability. The overtone modes are found to be stable.     

The Hallstatt solar cycle from radiocarbon data

The data on the ¹⁴C concentration in the Earth’s atmosphere are studied on a time span of 50000 years. It is shown that the Hallstatt cycle (a temporal variation with a period of 1500–2000 years) has been present in this series for at least 30000 years. However, this cycle is not purely of solar origin; nonsolar (supposedly climatic) factors contribute into it in certain epochs.     

The distribution of infrared radiative flux densities and their divergence along the symmetry line of an idealized valley

Summary This investigation concerns itself with the determination of infrared radiative flux divergence along the symmetry line of a cone. Such a cone, imbedded in the plane earth, is thought to idealize a large valley. The radiative transfer equations were set up in such a manner as to deal with the special geometry involved. It was found that radiative temperature changes within the valley are a strong function of the steepness of the valley walls.     

Seasonal features in the response of the mesopause temperature and emission intensities to solar activity variations

The seasonal dependences of the response of the hydroxyl ((6–2) band) and molecular oxygen O₂(b ¹Σ _g ⁺ ) ((0–1) band) emission intensities, temperature, and density indicator in the region of the hydroxyl emission maximum (87 km) to solar activity have been obtained based on the spectral observations of the mesopause emissions at Zvenigorod observatory during 2000–2007. The ratio of the OH (7–3) and (9–4) band intensities, characterizing the behavior of the vibrational temperature, has been used as an indicator of density. It has been established that the response of the studied mesopause characteristics to solar activity is positive in all seasons. In winter the response is maximal in the intensities and temperature and is minimal in the density indicator. The main mechanisms by which solar activity affects the mesopause characteristics have been considered. The behavior of the internal gravity waves with periods of 0.33–7 h depending on solar activity has been studied. It has been noted that these waves become more active at a minimum of the 11-year solar cycle.     

Longitudinal factor in the spatial distribution of energetic solar flares

Discrete location of large flares near zero Carrington longitude results in artificial breaks within physically related flare clusters. This effect is eliminated by using the data presentation algorithm, which results in the conclusion that drifting zones of intensified sunspot formation (concentrated cores of activity complexes) and energetic flare generation exist in either hemisphere. The indicated L zone is hypothetically related to a non-asymmetric relic solar magnetic field or to the regions where large-scale convective cells, extending to the convective zone bottom, originate.     

The equatorial ionospheric anomaly in electron content from solar minimum to solar maximum for South East Asia

Median hourly, electron content-latitude profiles obtained in South East Asia under solar minimum and maximum conditions have been used to establish seasonal and solar differences in the diurnal variations of the ionospheric equatorial anomaly (EIA). The seasonal changes have been mainly accounted for from a consideration of the daytime meridional wind, affecting the EIA diffusion of ionization from the magnetic equator down the magnetic field lines towards the crests. Depending upon the seasonal location of the subsolar point in relation to the magnetic equator diffusion rates were increased or decreased. This led to crest asymmetries at the solstices with (1) the winter crest enhanced in the morning (increased diffusion rate) and (2) the same crest decaying most rapidly in the late afternoon (faster recombination rate at lower ionospheric levels). Such asymmetries were also observed, to a lesser extent, at the equinoxes since the magnetic equator (located at about 9○N lat) does not coincide with the geographic equator. Another factor affecting the magnitude of a particular electron content crest was the proximity of the subsolar point, since this increased the local ionization production rate. Enhancements of the EIA took place around sunset, mainly during the equinoxes and more frequently at solar maximum, and also there was evidence of apparent EIA crest resurgences around 0300 LST for all seasons at solar maximum. The latter are thought to be associated with the commonly observed, post-midnight, ionization enhancements at midlatitudes, ionization being transported to low latitudes by an equatorward wind. The ratio increases in crest peak electron contents from solar minimum to maximum of 2.7 at the equinoxes, 2.0 at the northern summer solstice and 1.7 at northern winter solstice can be explained, only partly, by increases in the magnitude of the eastward electric field E overhead the magnetic equator affecting the [E×B] vertical drifts. The most important factor is the corresponding increase in ionization production rate due to the increase in solar radiation flux. The EIA crest asymmetries observed at solar maximum were less significant, and this is probably due to the corresponding increase in ionization densities leading to an increase of the retarding effect of ion-drag on the daytime meridional winds.     

Radiative properties of cirrus clouds in NOAA 4 VTPR channels: Some explorations of cloud scenes from satellites

A one-dimensional spectral infrared radiative transfer model has been developed for atmospheres containing cirrus clouds and absorbing gases above, below and within the cloud. The transfer model takes into consideration the inhomogeneity of the cloudy atmosphere, the gaseous absorption in scattering cloud layers and the wavenumber dependence of radiative transfer. In addition, the cirrus cloud is further divided into a number of sub-layers to account for the non-isothermal and inhomogeneous cloud characteristics. Single-scattering properties for ice crystals are calculated assuming ice cylinders 200 and 60 m in lenght and width, respectively, randomly oriented in a horizontal plane. The spectral infrared transfer program is applied to VTPR channels of the NOAA 4 satellite to simulate upward radiances in cirrus cloud conditions.Comparisons between satellite observed and theoretically simulated upward radiances are carried out for selected cirrus cloud cases. Incorporating atmospheric profiles obtained from radiosonde and the observed cloud information into the spectral transfer program, we show a systematic agreement between observed and computed upward radiances. Systematic reduction patterns of the upward radiance caused by the increase of the cloud ice content are clearly demonstrated for VTPR channels employing tropical and midlatitude atmospheric profiles. Having the quantitative relationships between upward radiances and ice contents, procedures are described for the inference of the cloud ice content and cloud amount. The proposed method has been successfully applied to the three cirrus cloud cases.     

The effect of weathering on optically stimulated luminescence dating

Optically stimulated luminescence (OSL) dating was applied to quartz samples recovered from the gravel sediments of deformed marine terrace at the Suryum site, southeastern Korea, but has yielded stratigraphically inconsistent ages. Micromorphological, chemical, and mineralogical analyses of the gravels indicate the possible influence of chemical weathering on the apparent OSL ages. In the course of weathering after emerging from beach environments, originally permeable gravels underwent infilling by halloysite-rich clays in their voids, export and import of radioactive elements, and loss of mechanical strength with the creation of a porosity within pebbles. Calculation based on the evolution of the weathering profile showed a severe fluctuation of dose rate caused by the change of water content and radioactive element concentrations. Samples recovered from the weathering profile inevitably include quartz grains derived from mechanically weakened pebbles or illuviated from the upper layer, making it difficult to determine the equivalent dose (D_e) values of exclusively depositional quartz sands. Quantitative evaluation of the change of fabric and chemistry of the sediments on the basis of pedologic insight significantly aids in the derivation of OSL ages consistent with geomorphology and other independent age controls.     

Spatio-temporal characteristics of aerosol distribution over Tibetan Plateau and numerical simulation of radiative forcing and climate response

In this paper we have analyzed aerosol distribution over the Tibetan Plateau by using the global monthly mean satellite data of Stratospheric Aerosol and Gas Experiment II (SAGE II). The results are as follows: (1) Stratospheric aerosol optical depth can oscillate in the four seasons. It means that the aerosol optical depth is the thickest in winter and a little thinner in spring and the thinnest in summer and then a little thicker in autumn. We have found that the oscillation is caused by the oscillation of tropopause in different seasons. (2) Stratospheric aerosol comes mainly from sprays of volcano. After eruption of Mount Pinatubo aerosol optical depth in stratosphere over the Tibetan Plateau increases 10 times compared with before. (3) The characteristic of aerosol vertical distribution over the Tibetan Plateau is that there is an extremely high value at the altitude of 70 hPa. The most interesting thing is that the extremely high value can oscillate between 50 hPa and 100 hPa. We have verified that the oscillation is a unique characteristic over the Tibetan Plateau by comparing it with South China and North China. Then the radiative forcing and regional climate response over the Tibetan Plateau of aerosol are investigated. We have discovered such things as followed by: (1) The radiative forcing is positive because the parameterized aerosol optical depth is less than 0.14 which is the optical depth of the uniform background boundary aerosol layer. It is 0–3 W/m² in January and 0–4 W/m² in April and less than 3 W/m² in July and 3–6 W/m² in October. (2) Ground temperature rises 0.1–0.2 K in October which is the biggest increasing magnitude, and 0.01–0.02 in July which is the smallest one. It rises about 0.05-0.01 K in January and April. (3) Air temperature near the earth’s surface and the one at the altitude of 500 hPa rise too, but the increasing magnitude is less than the former one.

     

The records of solar wind and solar flares in aubrites

A large number of individual enstatite crystals of the gas-rich aubrites Khor Temiki, Staroe Pesyanoe and Bustee was analyzed for implanted helium and for steep gradient ion tracks in order to investigate the relation between solar flare irradiation and solar wind implantation with extreme local resolution. Irradiated and non-irradiated crystals coexist within the gas-rich phases of the aubrites investigated. Statistically in a given meteorite the proportion of crystals with implanted solar wind is similar to the proportion of solar flare irradiated crystals. It varies from aubrite to aubrite in the sequence of their bulk contents of trapped rare gases.For nine enstatites, tracks and rare gases were subsequently measured within the same crystal. The results support the intimate association of solar flare tracks and implanted He. The⁴He-surface concentrations of irradiated crystals vary between <5 × 10^?7 and 10^?4 cm³ STP/cm².The absence of saturation effects together with the low degree of elemental gas fractionation indicates very short solar wind exposure times (< 100 yr) rather than strong diffusion losses. The evidence from tracks and rare gases can be understood in terms of an early simultaneous irradiation of aubritic crystals by solar wind and solar flare particles on top of a regolith-covered parent body.     

Relation between the structure of particles of the dispersion layer and its spectral optical thickness in an optically thin environment

Summary The paper focuses on the applicability of simple optimizing methods to determining the aerosol structure based on the measured values of the spectral optical thickness of aerosol δ(λ). The necessary conditions leading to a stable solution are assessed. By applying the particle distribution function in the form of summations of modified gamma functions we obtain the simple form of δ(λ). It is not suitable for proving Gaussian functions. The application of approximate methods to determine the aerosol structure from spectral optical thickness of atmospheric aerosol is based on measurements of the direct spectral solar radiation flux density which formed a part of the radiation experiment conducted in Zingst (Germany) on the coast of the Baltic Sea in 1987. on leave from the Astronomical Institute, Slovak Academy of Sciences     

The effect of radiative heat loss on steady cellular convection

Summary In the atmosphere there may be layers undergoing cellular convection with a much larger heat flux through the base of the layer than through the top. This may be either because there is a steady loss of heat by radiation from the body of the fluid or because the temperature is everywhere rising. In this latter case the temperature gradients could remain constant so that the mechanics would be the same as if the heat were being lost and the temperature kept steady. The fluid is considered incompressible as in the classical theory of cellular convection, and we determine the critical Rayleigh number for the onset of convection and the width to height ratio of the cells as functions of the heat loss. The problem, is in some respects analogous to that of the motion of a viscous fluid between rotating cylinders but in this case there are two non-dimensional-numbers-the Rayleigh number (g h ⁴/K v) and a number representing the ratio of the heat loss by radiation to the heat flux. It is found that the critical Rayleigh number is decreased and the cells widened as had already been found for the case of a fluid with transfer coefficients having a spatial variation, with free boundaries, but the cells are made more narrow if the boundaries are rigid.