Effects Of Vertical Transport Research Articles

A new scenario applying traffic flow analogy to poleward expansion of auroras

Abstract. Transient westward electric fields from the magnetosphere generate equatorward plasma drifts of the order of kilometers per second in the auroral ionosphere. This flow channel extends in north–south directions and is produced in the initial pulse of Pi2 pulsations associated with the field line dipolarization. Drifts in the ionosphere of the order of kilometers per second that accumulated plasmas at the low-latitude end of the flow channel are of such large degree that possible vertical transport effects (including precipitation) along the field lines may be ignored. In this condition, we suggest that plasma compression in the ionosphere initiated the dynamic ionosphere. The dynamic ionosphere includes a nonlinear evolution of the compressed ionospheric plasmas, generation of field-aligned currents to satisfy the quasi-neutrality of the ionosphere, and parallel potentials associated with the excitation of an ion acoustic wave. We will study how the dynamic ionosphere created auroral expansion.

Smart house: model of resource management and safety of vertical transport

It has been proven that the vertical transport occupies a niche not so much technical objects, how many socially significant technological advances that provide comfort and accessibility for the population of different levels of mobility. Analysis of legal, regulatory documentation showed that the security and reliability of vertical transport is represented in the theory of risk as a scenario of possible events with a broad range of assumptions within the zone of progressing temporary uncertainty and coherence mechanism models of actual conditions, in most cases, it is not. Evaluated scientific elaboration area studies in part integrity, functionality and consistency of the regulatory framework legal enforceability. The model of the complete life cycle of vertical transport. Algorithm of modal analysis of vertical transport parameters of criteria. Estimation of interference and strengthening process factors. Conducted simulation risk factor system the effects of vertical transport the negative socio-economic consequences. Proposed personalized predictive model of full life-cycle operation of vertical transport. Practical recommendations aimed at harmonizing the basic works on scientific and technical support and monitoring, simplification of the development programs of work, obtaining accurate and timely information on the state of vertical transport.

Evaluation of Subgrid-Scale Hydrometeor Transport Schemes Using a High-Resolution Cloud-Resolving Model

Abstract Potential ways of parameterizing vertical turbulent fluxes of hydrometeors are examined using a high-resolution simulation of continental deep convection. The cloud-resolving model uses a double-moment microphysics scheme that contains prognostic variables for four hydrometeor types: rain, graupel, cloud ice, and snow. The benchmark simulation with a horizontal grid spacing of 250 m is analyzed to evaluate three different ways of parameterizing the turbulent vertical fluxes of hydrometeors: an eddy-diffusion approximation, a quadrant-based decomposition, and a scaling method that accounts for within-quadrant (subplume) correlations. Results show that the downgradient nature of the eddy-diffusion approximation enforces transport of mass away from concentrated regions, whereas the benchmark simulation indicates that the vertical transport often moves mass from below the level of maximum concentration to aloft. Unlike the eddy-diffusion approach, the quadrimodal decomposition is able to capture the signs of the flux gradient but underestimates the magnitudes. The scaling approach, which accounts empirically for within-quadrant correlations, improves the representation of the vertical fluxes for all hydrometeors except snow. A sensitivity study is performed to illustrate how vertical transport effects on the vertical distribution of hydrometeors are compounded by accompanying changes in microphysical process rates. Results from the sensitivity tests show that suppressing rain or graupel transport drastically alters vertical profiles of cloud ice and snow through changes in the distribution of cloud water, which in turn governs the production of cloud ice and snow aloft. Last, a viable subgrid-scale hydrometeor transport scheme in an assumed probability density function parameterization is discussed.

Aerosol Size Distribution, Particle Concentration, and Optical Property Variability near Caribbean Trade Cumulus Clouds: Isolating Effects of Vertical Transport and Cloud Processing from Humidification Using Aircraft Measurements

Abstract This paper examines the effect of trade wind cumulus clouds on aerosol properties in the near-cloud environment using data from the Rain in Cumulus over the Ocean (RICO) campaign. Aerosol size distributions, particle concentrations, and optical properties are examined as a function of altitude and distance from cloud, at ambient relative humidity (RH) and adjusted to a constant RH to isolate effects of humidification from other processes. The cloud humidity halo extended about 1500–2000 m from the cloud edge, with no clear altitude dependence on horizontal extent over an altitude range of 600–1700 m. The combined effects of vertical transport of aerosol by clouds and cloud processing contributed to the modification of aerosol size distributions within the clouds' humidity halos, particularly close to the cloud boundaries. Backscatter at 532 nm, calculated from the aerosol properties, exhibited no distinguishable trend with altitude within 400 m of cloud edges, increased toward lower altitudes beyond 400 m, and decreased away from cloud boundaries at all altitudes. The mean aerosol diameter was found to rapidly decline from 0.8 to 0.4 μm from near the cloud boundary to the boundary of the humidity halo. Aerosol optical depth at 532 nm within the layer between 600 and 1700 m increased near exponentially from 0.02 to 0.2 toward the cloud boundaries within the humidity halo. These trends agreed qualitatively with past space-based lidar measurements of trade wind cloud margins, although quantitative differences were noted that likely arose from different sampling strategies and other factors.

What causes long‐term temporal changes in the south Atlantic?

Two zonal sections at 11°S in the South Atlantic, separated in time by 11 years, provide temperature differences in the deep ocean. The aim of this case study is to check whether intrinsic temperature changes are sufficiently large to identify long‐term water mass property variations which could be related to climate change. Potential temperature differences on isobaric surfaces in the deep ocean here reach several tenths of °C. They can be caused by vertical (cross‐isopycnal) or horizontal (isopycnal) advection and mixing, or by intrinsic water mass changes. The effect of vertical transport is removed by using neutral (density) surfaces. The effect of horizontal transport is determined by using a mixing parameterization for temperature and silica on neutral surfaces. The residual intrinsic temperature changes are, with a few local exceptions, within the range of the ±0.05°C uncertainty, and the temperature changes can thus be explained by advection and mixing alone.

Inverse modeling of annual atmospheric CO2 sources and sinks: 2. Sensitivity study

Atmospheric transport models can be used to infer surface fluxes of atmospheric CO2 from observed concentrations using inverse methods. One of the main problem of these methods is the question of their sensivity to all the parameters involved in the calculation. In this paper we study precisely the influence of the main parameters on the net CO2 fluxes inferred by an annual Bayesian three‐dimensional (3‐D) inversion of atmospheric CO2 monthly concentrations. This inversion is described as the control inversion (S0) of Bousquet et al. [this issue]. Successively, at regional to global spatial scales we analyze the numerical stability of the solution to initial fluxes and errors, the influence of a priori flux scenario, the sensitivity to the atmospheric transport model used, the influence of δ13C measurements, and the influence of the atmospheric network. We find that the atmospheric transport model introduces a large uncertainty to the inferred budget, which overcomes our control run uncertainties. The effects of vertical transport on CO2 concentrations appear to be a critical point that has to be investigated further. Spatial patterns of fluxes also have significant influence on a regional basis. We notice that accounting for the Baltic Sea station (BAL) deeply modifies the Europe versus Asia partition of the land uptake at mid and high latitudes of the Northern Hemisphere. We also analyze the weak influence of using δ13C measurements as additional constraints. In the tropics we find that the low level of constraints imposed by the atmospheric network limits the analysis of fluxes to zonal means. Finally, we calculate overall estimates of CO2 net sources and sinks at continental scale, accounting for all sensivity tests. Concerning the controversial partition of CO2 sink at mid and high latitudes of the Northern Hemisphere, we find (on average, for the 1985–1995 period) an overall partition of the sink of 0.7±0.7 Gt C yr1 for North America, 0.2±0.3 Gt C yr−1 for the North Pacific Ocean, 0.5±0.8 Gt C yr−1 for Europe, 0.7±0.3 Gt C yr−1 for the North Atlantic Ocean, and 1.2±0.8 Gt C yr−1 for north Asia. This overall partition tends to place an important land uptake over north Asia. However, uncertainties remain large when we account for all the sensitivity tests.

Effect of vertical transport on superlattice luminescence in the presence of an in-plane magnetic field

The effect of the vertical transport of carriers on the luminescence from a ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}\mathrm{As}$ superlattice (SL) in the presence of a magnetic field is studied both experimentally and theoretically. Measurements are reported for magnetic fields directed both perpendicular and parallel to the SL axis and taking values up to 42 T. In the case of an in-plane magnetic field, two threshold fields ${B}_{1}$ and ${B}_{2}$ are defined. The lower field ${B}_{1},$ which is measured experimentally, corresponds to the field at which resonance between the minibands of neighboring SL quantum wells (QW's) is destroyed. The higher field ${B}_{2}$ corresponds to the field at which the carriers remain completely localized within the QW. A theoretical model is used to analyze these results by approximating the SL potential to \ensuremath{\delta}-function-type barriers. The measured and calculated values of ${B}_{1}$ are found to be in a good agreement with each other.

Variability of the neutral mesospheric and lower thermospheric composition in the diurnal cycle

A non-steady one-dimensional model atmosphere, including N 2, oxygen, hydrogen and carbon compounds, suitable for the interpretation of the processes occurring during twilight, has been developed for mid-latitude and equinox conditions at altitudes from 60 to 220 km. The temporal dependence of the photodissociation coefficients has been calculated in detail, paying special attention to twilight conditions. Photochemical processes for the different compounds are considered using the latest reaction rate coefficients. Vertical transport effects are also included, considering molecular diffusion and a semiempirical eddy diffusion coefficient profile. The Variability of the different compounds throughout a complete day is obtained and compared with other theoretical models and experimental measurements. Special emphasis is paid to the study of the rapid changes occurring during morning and evening twilight times in the concentration of various minor compounds. The results obtained have been applied to the study of the diurnal evolution of the O 2( 1Δ g) and OH emissions derived from appropriate photochemical schemes. A reasonable agreement is achieved between different measurements and our predictions and this may be taken to validate the model.

Minor stratospheric warmings and their relation to the ionosphere

Five minor stratospheric warmings occurring in the 1983-84 winter, and sensed by reversal of thermospheric winds, are examined. Evidence is presented of neutral atmosphere - ionospheric coupling occurring over large areas with minima in radio-wave absorption coinciding with the warmings. D-region electron concentrations are depleted by day and lower E-region electron concentrations depleted by night. Vertical transport effects, linked to the horizontal winds, are invoked as the probable cause of the movement of ionisable constituents (e.g., nitric oxide) or ionisation, required to explain the observations.

Ozone, ultraviolet flux and temperature of the paleoatmosphere.

Of all tropospheric species, ozone (O3) comes closest to being naturally present at toxic levels. In addition, O3 controls the ultraviolet flux reaching the Earth's surface and affects the temperature of the surface and atmosphere. For these reasons, O3 was an important species of the paleoatmosphere. Surface and atmospheric levels of paleoatmospheric O3 were calculated using a detailed photochemical model, including the chemistry of the oxygen, nitrogen, and hydrogen species and the effects of vertical transport. Surface and tropospheric O3, as well as the total O3 column, were found to maximize for an atmospheric oxygen level of 10(-1) present atmospheric level (PAL). Coupled photochemica/radiative-convective calculations indicate that the radiative effects of O3 corresponding to an oxygen level of 10(-1) PAL resulted in a globally-averaged surface temperature increase of 4.5 K.

Distribution of hydrogen and helium in the upper atmosphere

A general review of the principal parameters influencing the helium and hydrogen distributions is presented for several physical conditions which are responsible for the upper atmospheric structure. The main differences between the helium and the hydrogen problems are pointed out. In particular, the effect of vertical transport is not similar for the two components. Helium is mainly dominated by the eddy diffusion coefficient whereas, in the case of hydrogen, the vertical flow is the lead ng factor. It is also shown how eddy diffusion can play a role in the structure of the helium bulge which is now very well confirmed by satellite observations.