Influence of parameterized small-scale gravity waves on the migrating diurnal tide in Earth's thermosphere

Effects of subgrid-scale gravity waves (GWs) on the diurnal migrating tides are investigated from the mesosphere to the upper thermosphere for September equinox conditions, using a general circulation model coupled with the extended spectral nonlinear GW parameterization of Yi\u{g}it et al (2008). Simulations with GW effects cut-off above the turbopause and included in the entire thermosphere have been conducted. GWs appreciably impact the mean circulation and cool the thermosphere down by up to 12-18%. GWs significantly affect the winds modulated by the diurnal migrating tide, in particular in the low-latitude mesosphere and lower thermosphere and in the high-latitude thermosphere. These effects depend on the mutual correlation of the diurnal phases of the GW forcing and tides: GWs can either enhance or reduce the tidal amplitude. In the low-latitude MLT, the correlation between the direction of the deposited GW momentum and the tidal phase is positive due to propagation of a broad spectrum of GW harmonics through the alternating winds. In the Northern Hemisphere high-latitude thermosphere, GWs act against the tide due to an anti-correlation of tidal wind and GW momentum, while in the Southern high-latitudes they weakly enhance the tidal amplitude via a combination of a partial correlation of phases and GW-induced changes of the circulation. The variable nature of GW effects on the thermal tide can be captured in GCMs provided that a GW parameterization (1) considers a broad spectrum of harmonics, (2) properly describes their propagation, and (3) correctly accounts for the physics of wave breaking/saturation.Comment: Accepted for publication in Journal of Geophysical Research - Space Physic

Role of gravity waves in vertical coupling during sudden stratospheric warmings

Gravity waves are primarily generated in the lower atmosphere, and can reach thermospheric heights in the course of their propagation. This paper reviews the recent progress in understanding the role of gravity waves in vertical coupling during sudden stratospheric warmings. Modeling of gravity wave effects is briefly reviewed, and the recent developments in the field are presented. Then, the impact of these waves on the general circulation of the upper atmosphere is outlined. Finally, the role of gravity waves in vertical coupling between the lower and the upper atmosphere is discussed in the context of sudden stratospheric warmings.Comment: Accepted for publication in Geoscience Letter

Gravity waves and high-altitude CO2_2 ice cloud formation in the Martian atmosphere

We present the first general circulation model simulations that quantify and reproduce patches of extremely cold air required for CO$_2$ condensation and cloud formation in the Martian mesosphere. They are created by subgrid-scale gravity waves (GWs) accounted for in the model with the interactively implemented spectral parameterization. Distributions of GW-induced temperature fluctuations and occurrences of supersaturation conditions are in a good agreement with observations of high-altitude CO$_2$ ice clouds. Our study confirms the key role of GWs in facilitating CO$_2$ cloud formation, discusses their tidal modulation, and predicts clouds at altitudes higher than have been observed to date.Comment: Accepted for publication in Geophysical Research Letters (GRL

Environmental urbanization assessment using gis and multicriteria decision analysis: a case study for Denizli (Turkey) municipal area

In recent years, life quality of the urban areas is a growing interest of civil engineering. Environmental quality is essential to display the position of sustainable development and asserts the corresponding countermeasures to the protection of environment. Urban environmental quality involves multidisciplinary parameters and difficulties to be analyzed. The problem is not only complex but also involves many uncertainties, and decision-making on these issues is a challenging problem which contains many parameters and alternatives inherently. Multicriteria decision analysis (MCDA) is a very prepotent technique to solve that sort of problems, and it guides the users confidence by synthesizing that information. Environmental concerns frequently contain spatial information. Spatial multicriteria decision analysis (SMCDA) that includes Geographic Information System (GIS) is efficient to tackle that type of problems. This study has employed some geographic and urbanization parameters to assess the environmental urbanization quality used by those methods. The study area has been described in five categories: very favorable, favorable, moderate, unfavorable, and very unfavorable. The results are momentous to see the current situation, and they could help to mitigate the related concerns. The study proves that the SMCDA descriptions match the environmental quality perception in the city. © 2018 Erdal Akyol et al

The Demand for Medical Care in Urban China

This is the first paper to investigate the determinants of the demand for medical care in the People's Republic of China. It uses a data set that consists of detailed characteristics of 6407 urban households, a continuous measure of health care spending, and price. A two-part model and a discrete factor model are used in the estimation. Household characteristics and work conditions impact the demand for medical care. Income elasticity is around 0.3, indicating medical care is a necessity. Medical care demand is price inelastic, and price elasticity is larger in absolute value for poorer households.

Hyperuniformity of Quasicrystals

Hyperuniform systems, which include crystals, quasicrystals and special disordered systems, have attracted considerable recent attention, but rigorous analyses of the hyperuniformity of quasicrystals have been lacking because the support of the spectral intensity is dense and discontinuous. We employ the integrated spectral intensity, $Z(k)$, to quantitatively characterize the hyperuniformity of quasicrystalline point sets generated by projection methods. The scaling of $Z(k)$ as $k$ tends to zero is computed for one-dimensional quasicrystals and shown to be consistent with independent calculations of the variance, $\sigma^2(R)$, in the number of points contained in an interval of length $2R$. We find that one-dimensional quasicrystals produced by projection from a two-dimensional lattice onto a line of slope $1/\tau$ fall into distinct classes determined by the width of the projection window. For a countable dense set of widths, $Z(k) \sim k^4$; for all others, $Z(k)\sim k^2$. This distinction suggests that measures of hyperuniformity define new classes of quasicrystals in higher dimensions as well.Comment: 12 pages, 14 figure

Internal gravity waves in the thermosphere during low and high solar activity: Simulation study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95256/1/jgra20438.pd