Some Applied Aspects of the Study of Trends in the Upper and Middle Atmosphere

Geomagnetism and Aeronomy - It is shown that that there are currently trends in the parameters of the middle and upper atmosphere and ionosphere that are already leading or may lead in the near...     

Propagation of Stationary Planetary Waves in the Upper Atmosphere under Different Solar Activity

Numerical modeling of changes in the zonal circulation and amplitudes of stationary planetary waves are performed with an accounting for the impact of solar activity variations on the thermosphere. A thermospheric version of the Middle/Upper Atmosphere Model (MUAM) is used to calculate the circulation in the middle and upper atmosphere at altitudes up to 300 km from the Earth’s surface. Different values of the solar radio emission flux in the thermosphere are specified at a wavelength of 10.7 cm to take into account the solar activity variations. The ionospheric conductivities and their variations in latitude, longitude, and time are taken into account. The calculations are done for the January–February period and the conditions of low, medium, and high solar activity. It was shown that, during high-activity periods, the zonal wind velocities increases at altitudes exceeding 150 km and decreases in the lower layers. The amplitudes of planetary waves at high solar activity with respect to the altitude above 120 km or below 100 km, respectively, are smaller or larger than those at low activity. These differences correspond to the calculated changes in the refractive index of the atmosphere for stationary planetary waves and the Eliassen–Palm flux. Changes in the conditions for the propagation and reflection of stationary planetary waves in the thermosphere may influence the variations in their amplitudes and the atmospheric circulation, including the lower altitudes of the middle atmosphere.     

Density Perturbations in the Upper Atmosphere Caused by the Dissipation of Solar Wind Energy

The upper atmosphere constitutes the outer region of the terrestrial gas envelope above about 100 km altitude. The energy budget of this outer gas layer is partly controlled by the dissipation of solar wind energy. Since this energy input is largely irregular, the resulting density changes are considered as perturbations. The properties and physics of such density perturbations are reviewed here. Besides being an important link in the complex chain of solar-terrestrial relations, such disturbances are also of practical interest because they affect the orbits of satellites and space stations and are responsible for ionospheric disturbance effects.     

Long-Term Variations in the Parameters of the Middle and Upper Atmosphere and Ionosphere (Review)

Geomagnetism and Aeronomy - The article reviews the main publications from the last eight years on long-term trends in the parameters of the middle atmosphere, thermosphere, and ionosphere. It is...     

Effects Of Geomagnetic Storms – Different Morphology and Origin in the Upper Middle Atmosphere and the Troposphere

Compiling various experimental as well as theoretical results, we find that the effects of geomagnetic storms in the upper middle atmosphere (heights about 60 – 100 km) and the troposphere are of different morphology, origin and nature.     

Assessment of the Ionization Effect During the Distribution of a Toroidal Plasma Bunch in a Diluted Atmosphere

Geomagnetism and Aeronomy - Earlier, we carried out detailed numerical studies of the initial stage of the formation and movement of a toroidal plasma bunch after its flight from a plasma gun, and...     

美国罗德河流域地下水中铝形成动力学

In the Rhode River estuarine/watershed area, increased acidity of precipitation from atmospheric acidic deposition has deleterious effects on the freshwater ecosystems. One of the characteristics of an acidic watershed is the mobilization of aluminum from soils to aquatic environment. Increased concentrations of aluminum in surface waters are toxic to living organisms. Detection of long-term changes of acidity and elevated Al concentrations in surface and soil waters is a central issue. In this present paper, the dynamics ofAl speciation in the shallow ground waters from Rhode River watershed 110 (la) were investigated. This research provides a unique, regional analysis of important controls on the transport of Al speciation through the rural watershed of the Chesapeake Bay.     

Sensitivity of Mesoscale Model Forecast During a Satellite Launch to Different Cumulus Parameterization Schemes in MM5

The identification of the model discrepancy and skill is crucial when a forecast is issued. The characterization of the model errors for different cumulus parameterization schemes (CPSs) provides more confidence on the model outputs and qualifies which CPSs are to be used for better forecasts. Cases of good/bad skill scores can be isolated and clustered into weather systems to identify the atmospheric structures that cause difficulties to the forecasts. The objective of this work is to study the sensitivity of weather forecast, produced using the PSU-NCAR Mesoscale Model version 5 (MM5) during the launch of an Indian satellite on 5th May, 2005, to the way in which convective processes are parameterized in the model. The real-time MM5 simulations were made for providing the weather conditions near the launch station Sriharikota (SHAR). A total of 10 simulations (each of 48 h) for the period 25th April to 04th May, 2005 over the Indian region and surrounding oceans were made using different CPSs. The 24 h and 48 h model predicted wind, temperature and moisture fields for different CPSs, namely the Kuo, Grell, Kain-Fritsch and Betts-Miller, are statistically evaluated by calculating parameters such as mean bias, root-mean-squares error (RMSE), and correlation coefficients by comparison with radiosonde observation. The performance of the different CPSs, in simulating the area of rainfall is evaluated by calculating bias scores (BSs) and equitable threat scores (ETSs). In order to compute BSs and ETSs the model predicted rainfall is compared with Tropical Rainfall Measuring Mission (TRMM) observed rainfall. It was observed that model simulated wind and temperature fields by all the CPSs are in reasonable agreement with that of radiosonde observation. The RMSE of wind speed, temperature and relative humidity do not show significant differences among the four CPSs. Temperature and relative humidity were overestimated by all the CPSs, while wind speed is underestimated, except in the upper levels. The model predicted moisture fields by all CPSs show substantial disagreement when compared with observation. Grell scheme outperforms the other CPSs in simulating wind speed, temperature and relative humidity, particularly in the upper levels, which implies that representing entrainment/detrainment in the cloud column may not necessarily be a beneficial assumption in tropical atmospheres. It is observed that MM5 overestimates the area of light precipitation, while the area of heavy precipitation is underestimated. The least predictive skill shown by Kuo for light and moderate precipitation asserts that this scheme is more suitable for larger grid scale (>30 km). In the predictive skill for the area of light precipitation the Betts-Miller scheme has a clear edge over the other CPSs. The evaluation of the MM5 model for different CPSs conducted during this study is only for a particular synoptic situation. More detailed studies however, are required to assess the forecast skill of the CPSs for different synoptic situations.     

Surface and Upper Air Fields During Extreme Winter Precipitation Over the Western Himalayas

Surface and upper air circulation features associated with extreme precipitation years are demonstrated during winter season viz., December, January, February and March (DJFM) to examine winter weather affecting the western Himalayas. These circulations are studied over the domain 15°S–45°N and 30°E–120°E. This domain is considered particularly to illustrate the distribution of precipitation due to a wintertime eastward moving synoptic weather system called western disturbances. Surplus and deficient years of seasonal (DJFM) precipitation are identified using ± 20% departure from mean from uninitialized daily reanalysis data of forty (1958–1997) years of the National Center For Environmental Prediction (NCEP), US. The years 1965–1969, 1973 and 1991 are found to be surplus years and the years 1962, 1963, 1971, 1977, and 1985 are found to be deficient years. Comparative study between composites of these two categories is made using students t-test of significance. Significant differences in sea-level pressure, zonal and meridional component of wind at surface and upper levels, total precipitable water content, geopotential height and temperature are observed in the two contrasting seasons.     

Viscosity Coefficient of the Multicomponent Neutral Atmosphere

The viscosity coefficient of the multicomponent neutral atmosphere calculated from the general hydrodynamic expression of a multicomponent gas mixture is compared with the approximations published and proposed in this paper for this coefficient. Two new approximate expressions for the viscosity coefficient of the multicomponent atmosphere have been found. Their relative calculation errors do not exceed 3.4 and 4.8% in the altitude range of 100 to 500 km for low, moderate, and high solar activity during daytime and nigthtime geomagnetically quiet and geomagnetically disturbed conditions at low, middle, and high latitudes. These errors are significantly smaller than the maximum relative errors (11.8–15.1%) of the viscosity coefficient calculations based on the approximations used in atmospheric studies for this coefficient. The new approximate expressions for the viscosity coefficient of the multicomponent atmosphere are recommended to be used in atmospheric studies to reduce errors in calculating atmospheric parameters.     

Variations in the Polar Mesospheric Summer Echoes during the Appearance of Irregularities of Noctilucent Clouds

Variations in the amplitude of the ordinary wave from a received signal on a partial reflection radar at a short-wave range on the Kola Peninsula during the appearance of noctilucent clouds on August 12, 2016, are examined. Noctilucent clouds are registered by the all-sky camera located 100 km southward of the partial reflection radar. They extended over the entire celestial hemisphere observed by the all-sky camera; all of them moved in the southern direction, and the clouds had a tenuous structure and showed gravity waves with spatial periods of 15–100 km. During the presence of noctilucent clouds over the partial reflection radar, polar mesospheric summer echoes (PMSEs) were recorded at heights of 83–86 km. It was found that the presence of only noctilucent clouds in diagram of the antenna pattern of partial frequency radar is not sufficient for the appearance of PMSEs; noctilucent clouds must also have irregularities of several kilometers. The PMSE heights decreased with a velocity of 0.5 and 1.3 m/s. The issue of aerosols that cause the appearance of PMSEs and noctilucent clouds is discussed.     

Microparticles in the Atmosphere from Lithospheric Sources of Technogenic Origin

Izvestiya, Physics of the Solid Earth - Abstract—There is a brief overview of technogenic sources of microparticles associated with the extraction of mineral raw materials and fuel from the...     

The Electric Field in the Surface Atmosphere of the Megapolis of Moscow

Geomagnetism and Aeronomy - The results of instrumental observations of the electric-field strength in the conditions of Moscow in 2014–2018 are presented and analyzed. The spectral...     

Metals in Sediments of the Upper Laguna Madre

The Laguna Madre system is the largest hypersaline coastal basin in the United States. Surface sediments from 22 Upper Laguna Madre (ULM) sites were analyzed for grain size and metals (Cd, Cu, Ba, Cr, Mn, Ni, Pb, V, Zn, Fe, and Al) to assess the extent of contamination in the area. Sediments were found to consist mainly of sand texture. Clay and silts were minor constituents (<10%) of the sediments. Anomalies in metal concentrations were found at some sites and were related to probable sources, i.e., recreational and industrial activities. Concentrations of metals were normalized to grain size, Al, and Fe to distinguish natural and anthropogenic sources. Most metals showed positive correlations (p < 0.001) with Fe and Al, suggesting a natural variability of metal concentrations in sediments. Concentrations of metals, except Cd and Pb, at most sites were found to be below threshold concentrations thought to produce toxic effects in marine and estuarine organisms.     

Anomalous Heating of the Solar Atmosphere in the Epoch of the Solar Activity Minimum

Geomagnetism and Aeronomy - The article studies the physical mechanism of the generation of a steady stream of weak shock waves at the photospheric level during the epoch of the solar-activity...     

Experimental Study of Small-Scale Mineral Particles in the Atmosphere of Central Asia

An experimental study of small-scale mineral particles in the atmosphere over Kyrgyzstan is carried out. It is shown that the substance of the studied particles corresponds to quartz-enriched minerals, feldspars, layered silicates, minerals containing lime carbonate, etc. Overall, there is a definite correspondence between the mineral particle compositions in the atmosphere of Kyrgyzstan and in the other regions of Central Asia. The constructed size-distribution functions of the particles agree with the results of studying the dust aerosol properties in the deserts of Central Asia obtained in the southwestern part of Tajikistan in 1989.     

Nonlinearities and Linearities in Internal Gravity Waves of the Atmosphere and Oceans

The spectrum of internal gravity waves in the atmosphere and oceans is sufficiently intense that nonlinear interactions must occur, if these waves are analyzed in Eulerian coordinates as is usually done. As it happens, however, if these waves are analyzed in Lagrangian coordinates the most important nonlinearity can be entirely avoided: it is an Eulerian mathematical construct only, not a physical process. The mathematical basis for this assertion is developed here, and some of its consequences are discussed. Among the latter is a questioning of the validity of standard Eulerian eikonal methods of calculating ray paths and related functions in a multiwave environment, discussed in an appendix.     

Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

Space-borne observations reveal that 20–40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column radiative–convective model of hydrostatic, nonlinear flow on a non-rotating sphere, with parameterized convection and radiation, and review ongoing efforts in high-resolution modeling and observations of warm rain. The model experiments investigate the response of convection and circulation to sea surface temperature (SST) gradients between the columns and to changes in a parameter that controls the conversion of cloud condensate to rain. Convection over the cold ocean collapses to a shallow mode with tops near 850 hPa, but a congestus mode with tops near 600 hPa can develop at small SST differences when warm rain formation is more efficient. Here, interactive radiation and the response of the circulation are crucial: along with congestus a deeper moist layer develops, which leads to less low-level radiative cooling, a smaller buoyancy gradient between the columns, and therefore a weaker circulation and less subsidence over the cold ocean. The congestus mode is accompanied with more surface precipitation in the subsiding column and less surface precipitation in the deep convecting column. For the shallow mode over colder oceans, circulations also weaken with more efficient warm rain formation, but only marginally. Here, more warm rain reduces convective tops and the boundary layer depth—similar to Large-Eddy Simulation (LES) studies—which reduces the integrated buoyancy gradient. Elucidating the impact of warm rain can benefit from large-domain high-resolution simulations and observations. Parameterizations of warm rain may be constrained through collocated cloud and rain profiling from ground, and concurrent changes in convection and rain in subsiding and convecting branches of circulations may be revealed from a collocation of space-borne sensors, including the Global Precipitation Measurement (GPM) and upcoming Aeolus missions.