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Register a new userEigen Microstates and Their Evolution of Global Ozone at Different Geopotential Heights
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Studies on stratospheric ozone have attracted much attention due to its serious impacts on climate changes and its important role as a tracer of Earths global circulation. Tropospheric ozone as a main atmospheric pollutant damages human health as well as the growth of vegetation. Yet there is still a lack of a theoretical framework to fully describe the variation of ozone. To understand ozones spatiotemporal variance, we introduce the eigen microstate method to analyze the global ozone mass mixing ratio (OMMR) between 1979-01-01 and 2020-06-30 at 37 pressure layers. We find that eigen microstates at different geopotential heights can capture different climate phenomena and modes. Without deseasonalization, the first eigen microstates capture the seasonal effect and reveal that the phase of the intra-annual cycle moves with the geopotential heights. After deseasonalization, by contrast, the collective patterns from the overall trend, ENSO, QBO, and tropopause pressure are identified by the first few significant eigen microstates. The theoretical framework proposed here can also be applied to other complex Earth systems.
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The viscosity of water induces a vorticity near the free surface boundary. The resulting rotational component of the fluid velocity vector greatly complicates the water wave system. Several approaches to close this system have been proposed. Our analysis compares three common sets of model equations. The first set has a rotational kinematic boundary condition at the surface. In the second set, a gauge choice for the velocity vector is made that cancels the rotational contribution in the kinematic boundary condition, at the cost of rotational velocity in the bulk and a rotational pressure. The third set circumvents the problem by introducing two domains: the irrotational bulk and the vortical boundary layer. This comparison puts forward the link between rotational pressure on the surface and vorticity in the boundary layer, addresses the existence of nonlinear vorticity terms, and shows where approximations have been used in the models. Furthermore, we examine the conservation of mass for the three systems, and how this can be compared to the irrotational case.
Absorbing UV radiation, ozone protects life on Earth and plays a fundamental role in Earths temperature balance. The formation of ozone occurs through the ternary recombination reaction: O$_2$+O+M $rightarrow$ O$_3$+M, where M can be N$_2$, O$_2$ or Ar. Here, we developed a theoretical approach capable of modeling the formation of ozone molecules in ternary collisions, and applied it to the reaction with M=Ar because of extensive experimental data available. The rate coefficients for the direct formation of O$_3$ in ternary collisions O+O$_2$+Ar were computed for the first time as a function of collision energy, and thermally-averaged coefficients were derived for temperatures 5-900~K leading to a good agreement with available experimental data for temperatures 100-900~K. The present study shows that the formation of ozone in ternary collisions O+O$_2$+Ar at temperatures below 200~K proceeds through a formation of a temporary complex ArO$_2$, while at temperatures above 1000~K, the reaction proceeds mainly through a formation of long-lived vibrational resonances of O$_3^*$. At intermediate temperatures 200~K-1000~K, the process cannot be viewed as a two-step mechanism. In addition, it is found that the majority of O$_3$ molecules formed initially are weakly bound.
Some AdS$_3 times M_7$ type IIB vacua have been recently proposed to arise from D3-branes wrapped on a spindle, a sphere with conical singularities at the poles. We explicitly construct a generalization of these solutions corresponding to a class of electrically charged and rotating supersymmetric black strings in AdS$_5 times S^5$ with general magnetic fluxes on the spindle. We then perform a counting of their microstates using the charged Cardy formula. To this purpose, we derive the general form of the anomaly polynomial of the dual $mathcal{N} = (0 , 2)$ CFT in two dimensions and we show that it can be obtained via a simple gluing procedure.
Ozone in Earths atmosphere is known to have a radiative forcing effect on climate. Motivated by geochemical evidence for one or more nearby supernovae about 2.6 million years ago, we have investigated the question of whether a supernova at about 50 pc could cause a change in Earths climate through its impact on atmospheric ozone concentrations. We used the Planet Simulator (PlaSim) intermediate-complexity climate model with prescribed ozone profiles taken from existing atmospheric chemistry modeling. We found that the effect on globally averaged surface temperature is small, but localized changes are larger and differences in atmospheric circulation and precipitation patterns could have regional impacts.
Based on cosmological rates, it is probable that at least once in the last Gy the Earth has been irradiated by a gamma-ray burst in our Galaxy from within 2 kpc. Using a two-dimensional atmospheric model we have performed the first computation of the effects upon the Earths atmosphere of one such impulsive event. A ten second burst delivering 100 kJ/m^2 to the Earth penetrates to the stratosphere and results in globally averaged ozone depletion of 35%, with depletion reaching 55% at some latitudes. Significant global depletion persists for over 5 years after the burst. This depletion would have dramatic implications for life since a 50% decrease in ozone column density results in approximately three times the normal UVB flux. Widespread extinctions are likely, based on extrapolation from UVB sensitivity of modern organisms. Additional effects include a shot of nitrate fertilizer and NO2 opacity in the visible providing a cooling perturbation to the climate over a similar timescale. These results lend support to the hypothesis that a GRB may have initiated the late Ordovician mass extinction (Melott et al. 2004).
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