Meso-Scale Hydrologic Modeling for Climate Impact Assessments: A Conceptual and A Regresssion Approach

The paper presents two different approaches to hydrologic modeling for Climate Impact Assessments: A conceptual water balance model and a non-parametric regression model. They both are designed for modeling large-scale river basins (Meso-Scale) at a monthly time step and to accept GCM-based climate scenarios defined as changes in monthly precipitation and temperature. The data requirements for the models are historical, multi-annual series of mean monthly temperature, precipitation, and runoff. These data are used to calibrate the models. GCM data or user-defined sensitivity of climatic variable must be provided for the assessment analyses. The paper describes the theoretical bases of both approaches and presents the results of a comparison of the application of the models to the Vistula River Basin in Poland

A macroscopic quantum state analysed particle by particle

Explaining how microscopic entities collectively produce macroscopic phenomena is a fundamental goal of many-body physics. Theory predicts that large-scale entanglement is responsible for exotic macroscopic phenomena, but observation of entangled particles in naturally occurring systems is extremely challenging. Synthetic quantum systems made of atoms in optical lattices have been con- structed with the goal of observing macroscopic quantum phenomena with single-atom resolution. Serious challenges remain in producing and detecting long-range quantum correlations in these systems, however. Here we exploit the strengths of photonic technology, including high coherence and efficient single-particle detection, to study the predicted large-scale entanglement underlying the macroscopic quantum phenomenon of polarization squeezing. We generate a polarization-squeezed beam, extract photon pairs at random, and make a tomographic reconstruction of their joint quantum state. We present experimental evidence showing that all photons arriving within the squeezing coherence time are entangled, that entanglement monogamy dilutes entanglement with increasing photon density and that, counterintuitively, increased squeezing can reduce bipartite entanglement. The results provide direct evidence for entanglement of macroscopic numbers of particles and introduce micro-analysis to the study of macroscopic quantum phenomena

Atmospheric chemistry of gas-phase polycyclic aromatic hydrocarbons: formation of atmospheric mutagens.

The atmospheric chemistry of the 2- to 4-ring polycyclic aromatic hydrocarbons (PAH), which exist mainly in the gas phase in the atmosphere, is discussed. The dominant loss process for the gas-phase PAH is by reaction with the hydroxyl radical, resulting in calculated lifetimes in the atmosphere of generally less than one day. The hydroxyl (OH) radical-initiated reactions and nitrate (NO3) radical-initiated reactions often lead to the formation of mutagenic nitro-PAH and other nitropolycyclic aromatic compounds, including nitrodibenzopyranones. These atmospheric reactions have a significant effect on ambient mutagenic activity, indicating that health risk assessments of combustion emissions should include atmospheric transformation products

The scenario of two-dimensional instabilities of the cylinder wake under EHD forcing: A linear stability analysis

We propose to study the stability properties of an air flow wake forced by a dielectric barrier discharge (DBD) actuator, which is a type of electrohydrodynamic (EHD) actuator. These actuators add momentum to the flow around a cylinder in regions close to the wall and, in our case, are symmetrically disposed near the boundary layer separation point. Since the forcing frequencies, typical of DBD, are much higher than the natural shedding frequency of the flow, we will be considering the forcing actuation as stationary. In the first part, the flow around a circular cylinder modified by EHD actuators will be experimentally studied by means of particle image velocimetry (PIV). In the second part, the EHD actuators have been numerically implemented as a boundary condition on the cylinder surface. Using this boundary condition, the computationally obtained base flow is then compared with the experimental one in order to relate the control parameters from both methodologies. After validating the obtained agreement, we study the Hopf bifurcation that appears once the flow starts the vortex shedding through experimental and computational approaches. For the base flow derived from experimentally obtained snapshots, we monitor the evolution of the velocity amplitude oscillations. As to the computationally obtained base flow, its stability is analyzed by solving a global eigenvalue problem obtained from the linearized Navier–Stokes equations. Finally, the critical parameters obtained from both approaches are compared

Measurement of ambient aerosol hydration state at Great Smoky Mountains National Park in the southeastern United States

We present results from two field deployments of a unique tandem differential mobility analyzer (TDMA) configuration with two primary capabilities: identifying alternative stable or meta-stable ambient aerosol hydration states associated with hysteresis in aerosol hydration behavior and determining the actual Ambient hydration State (AS-TDMA). This data set is the first to fully classify the ambient hydration state of aerosols despite recognition that hydration state significantly impacts the roles of aerosols in climate, visibility and heterogeneous chemistry. The AS-TDMA was installed at a site in eastern Tennessee on the border of Great Smoky Mountains National Park for projects during the summer of 2006 and winter of 2007–2008. During the summer, 12% of the aerosols sampled in continuous AS-TDMA measurements were found to posses two possible hydration states under ambient conditions. In every case, the more hydrated of the possible states was occupied. The remaining 88% did not posses multiple possible states. In continuous measurements during the winter, 49% of the aerosols sampled possessed two possible ambient hydration states; the remainder possessed only one. Of those aerosols with multiple possible ambient hydration states, 65% occupied the more hydrated state; 35% occupied the less hydrated state. This seasonal contrast is supported by differences in the fine particulate (PM<sub>2.5</sub>) composition and ambient RH as measured during the two study periods. In addition to seasonal summaries, this work includes case studies depicting the variation of hydration state with changing atmospheric conditions

Faraday waves on a viscoelastic liquid

We investigate Faraday waves on a viscoelastic liquid. Onset measurements and a nonlinear phase diagram for the selected patterns are presented. By virtue of the elasticity of the material a surface resonance synchronous to the external drive competes with the usual subharmonic Faraday instability. Close to the bicriticality the nonlinear wave interaction gives rise to a variety of novel surface states: Localised patches of hexagons, hexagonal superlattices, coexistence of hexagons and lines. Theoretical stability calculations and qualitative resonance arguments support the experimental observations.Comment: 4 pages, 4figure

Evaluation of organic markers for chemical mass balance source apportionment at the Fresno Supersite

International audienceSources of PM2.5 at the Fresno Supersite during high PM2.5 episodes occurring from 15 December 2000?3 February 2001 were estimated with the Chemical Mass Balance (CMB) receptor model. The ability of source profiles with organic markers to distinguish motor vehicle, residential wood combustion (RWC), and cooking emissions was evaluated with simulated data. Organics improved the distinction between gasoline and diesel vehicle emissions and allowed a more precise estimate of the cooking source contribution. Sensitivity tests using average ambient concentrations showed that the gasoline vehicle contribution was not resolved without organics. Organics were not required to estimate hardwood contributions. The most important RWC marker was the water-soluble potassium ion. The estimated cooking contribution did not depend on cholesterol because its concentrations were below the detection limit in most samples. Winter time source contributions were estimated by applying the CMB model to individual and average sample concentrations. RWC was the largest source, contributing 29?31% of measured PM2.5. Hardwood and softwood combustion accounted for 16?17% and 12?15%, respectively. Secondary ammonium nitrate and motor vehicle emissions accounted for 31?33% and 9?15%, respectively. The gasoline vehicle contribution (3?10%) was comparable to the diesel vehicle contribution (5?6%). The cooking contribution was 5?19% of PM2.5. Fresno source apportionment results were consistent with those estimated in previous studies