ALBERT

Beschreibung: During early November 2013, the magnetosphere experienced concurrent driving by a coronal mass ejection (CME) during an ongoing high-speed stream (HSS) event. The relativistic electron response to these two kinds of drivers, i.e., HSS and CME, is typically different, with the former often leading to a slower buildup of electrons at larger radial distances, while the latter energizing electrons rapidly with flux enhancements occurring closer to the Earth.We present a detailed analysis of the relativistic electron response including radial profiles of phase space density as observed by both MagEIS and REPT instruments on the Van Allen Probes mission. Data from the MagEIS instrument establishes the behavior of lower energy (〈1MeV) electrons which span both intermediary and seed populations during electron energization. Measurements characterizing the plasma waves and magnetospheric electric and magnetic fields during this period are obtained by the EMFISIS instrument on board Van Allen Probes, SCM and FGM instruments onboard THEMIS, and the low altitude polar orbiting POES satellite. These observations suggest that, during this time period, both radial transport and local in-situ processes are involved in the energization of electrons. The energization attributable to radial diffusion is most clearly evident for the lower energy (〈1MeV) electrons, while the effects of in-situ energization by interaction of chorus waves are prominent in the higher energy electrons.

Beschreibung: We estimate gravity changes due to co-seismic horizontal deformation and inclined bathymetry (referred to as topographic effects in this study) associated with the 2011 Tohoku-Oki earthquake, using a layered half-space dislocation model. As an approximation, we represent inclined topography with ramp-body models in the near field of the earthquake, and calculate topographic effects from both an inclined seafloor and Moho. The Moho effect partly compensates that from the seafloor. An additional contribution comes from seawater column variations as the sloped seafloor moves trench-ward. Topographic effects are first-order contributions to co-seismic gravity changes for the 2011 Tohoku-Oki earthquake. After 300 km Gaussian smoothing, comparable to the spatial resolution of the Gravity Recovery and Climate Experiment (GRACE), topographic effects create a dominantly negative gravity pattern with amplitudes up to 1.1 μGal for oceanic areas surrounding the epicenter. There are discrepancies between model predictions (-10.4 to +6.9 μGal) and GRACE observations (-10.1 to +1.7 μGal). Errors in the adopted fault-slip model and difficulties in separating co- and post-seismic deformation may contribute to these, but topographic effects, currently neglected in dislocation models, are also responsible. Topographic effects ought to be included in co-seismic fault slip and related gravity modeling for the 2011 Tohoku-Oki earthquake and similar events in regions of steep topography.

Beschreibung: An efficient and positivity-preserving layer method is introduced to solve the radiation belt diffusion equation and is applied to study the bounce resonance interaction between relativistic electrons and magnetosonic waves. The layer method with linear interpolation, denoted by LM-L (layer method-linear), requires the use of a large number of grid points to ensure accurate solutions. We introduce a monotonicity- and positivity-preserving cubic interpolation method to be used with the Milstein-Tretyakov layer method. The resulting method, called LM-MC (layer method-monotone cubic), can be used to solve the radiation belt diffusion equation with a much smaller number of grid points than LM-L, while still being able to preserve the positivity of the solution. We suggest that LM-MC can be used to study long-term dynamics of radiation belts. We then develop a 2D LM-MC code and use it to investigate the bounce resonance diffusion of radiation belt electrons by magnetosonic waves. Using a previously published magnetosonic wave model, we demonstrate that bounce resonance with magnetosonic waves is as important as gyro-resonance; both can cause several orders of magnitude increase of MeV electron fluxes within one day. We conclude that bounce resonance with magnetosonic waves should be taken into consideration together with gyro-resonance.

Beschreibung: The complicated interplay between mass and photon transfer within a photocatalytic reactor calls for an integrated design approach. This work presents a model-based optimization approach for LED-based photocatalytic reactors. First, a model that describes the distribution of reactants and photons within a photocatalytic reactor is developed. Second, several design variables related to the reactor dimensions and light sources are optimized simultaneously using the photocatalytic degradation of toluene as a model system. The results demonstrate how different formulations of the problem can be used to either minimize the reactor cost or to obtain a specified concentration profile within the reactor.

Beschreibung: Using the Van Allen Probe in-situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (〉2nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs ( B z -IMF  〈 -2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region ( MLT  ~ 06:00 - 18:00, and L  〉 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90 o (corresponding anisotropic index A  〉 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A ), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However in the nighttime decreased magnetic field region ( MLT  ~ 18:00 - 06:00, and L  ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45 o and 135 o ( A  〈 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. These variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.

Beschreibung: Modulation of whistler mode chorus waves, which plays an important role in driving the pulsating aurora and other processes related to energetic electron dynamics, is an interesting but a long-standing unresolved problem. Here we utilize in situ observations from the THEMIS spacecraft to investigate the role of density variations in the modulation of the chorus wave amplitude, which forms a complementary study to the modulation of chorus by compressional Pc4–5 pulsations presented in a companion paper. We show that these density variations are correlated remarkably well with modulated chorus intensity and typically occur on a timescale of a few seconds to tens of seconds. Both density depletions (DD) and density enhancements (DE) are frequently correlated with increases in chorus wave amplitudes. Furthermore, density enhancements cause a lowering of the central frequencies of the generated chorus waves and vice versa. DD events are more likely to be related to quasi-periodic chorus emissions and thus may be related to the generation of the pulsating aurora. A systematic survey of both DD and DE events shows that DD events preferentially occur between premidnight and dawn, whereas DE events dominantly occur from dawn to noon. We also evaluate the growth rates of chorus waves using linear theory for both DD and DE events and show that both density depletions and enhancements can lead to an intensification of chorus wave growth. However, other potential mechanisms for chorus intensification caused by density variations such as wave trapping by density crests and troughs cannot be excluded.

Beschreibung: An online coupled regional climate-chemistry model called RegCCMS is used to investigate the interactions between anthropogenic aerosols and the East Asian summer monsoon (EASM) over East Asia. The simulation results show that the mean aerosol loading and optical depth over the region are 17.87 mg/m 2 and 0.25, respectively. Sulfate and black carbon (BC) account for approximately 61.2 % and 7.8 % of the total aerosols, respectively. The regional mean radiative forcing (RF) is approximately −3.64, −0.55 and +0.88 W/m 2 at the TOA for the total aerosol effect, the total aerosol direct effect, and the BC direct effect, respectively. The surface direct RF of BC accounts for approximately 31 % of the total RF of all aerosols. Because of the total aerosol effect, both the energy budgets and air temperature are considerably reduced in the region with high aerosol loadings, leading to decreases in the land-ocean air temperature gradient in summer. The total column absorbed solar radiation (TCASR) and surface air temperature (SAT) decrease by 8.4 W/m 2 and 0.31 K, respectively. This cooling effect weakens horizontal and vertical atmospheric circulations over East Asia. The wind speed at 850 hPa decreases by 0.18 m/s, and the precipitation decreases by 0.29 mm/d. The small responses of solar radiation, air temperature and atmospheric circulations to the BC warming effect are opposite to those of the total aerosol effect. The BC-induced enhancement of atmospheric circulation can increase local floods in South China, while droughts in North China may worsen in response to the BC semi-direct effect. The total aerosol effect is much more significant than the BC direct effect. The East Asian summer monsoon becomes weaker due to the total aerosol effect. However, this weakness could be partially offset by the BC warming effect. Sensitivity analyses further indicate that the influence of aerosols on the EASM might be more substantial in years when the southerlies or southwesterlies at 850 hPa are weak compared with years when the winds are strong. Changes in the EASM can induce variations in the distribution and magnitude of aerosols. Aerosols in the lower troposphere over the region can increase by 3.07 and 1.04 µg/m 3 due to the total aerosol effect and the BC warming effect, respectively.