1,076 research outputs found

    Exploring Aerosols near Clouds with High-Spatial-Resolution Aircraft Remote Sensing During SEAC4RS

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    Since aerosols are important to our climate system, we seek to observe the variability of aerosol properties within cloud systems. When applied to the satelliteborne Moderateresolution Imaging Spectroradiometer (MODIS), the Dark Target retrieval algorithm provides global aerosol optical depth (AOD; at 0.55 m) in cloudfree scenes. Since MODIS' resolution (500m pixels, 3 or 10km product) is too coarse for studying nearcloud aerosol, we ported the Dark Target algorithm to the highresolution (~50m pixels) enhancedMODIS Airborne Simulator (eMAS), which flew on the highaltitude ER2 during the Studies of Emissions, Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys Airborne Science Campaign over the United States in 2013. We find that even with aggressive cloud screening, the ~0.5km eMAS retrievals show enhanced AOD, especially within 6 km of a detected cloud. To determine the cause of the enhanced AOD, we analyze additional eMAS products (cloud retrievals and degradedresolution AOD), coregistered Cloud Physics Lidar profiles, MODIS aerosol retrievals, and groundbased Aerosol Robotic Network observations. We also define spatial metrics to indicate local cloud distributions near each retrieval and then separate into nearcloud and farfromcloud environments. The comparisons show that low cloud masking is robust, and unscreened thin cirrus would have only a small impact on retrieved AOD. Some of the enhancement is consistent with clearcloud transition zone microphysics such as aerosol swelling. However, 3D radiation interaction between clouds and the surrounding clear air appears to be the primary cause of the high AOD near clouds

    Effects of physics beyond the standard model on the neutrino charge radius: an effective Lagrangian approach

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    In this work, we look for possible new physics effects on the electromagnetic charge and anapole form factors, fQ(q2)f_Q(q^2) and fA(q2)f_A(q^2), for a massless Dirac neutrino, when these quantities are calculated in the context of an effective electroweak Yang-Mills theory, which induces the most general SUL(2)SU_L(2)--invariant Lorentz tensor structure of nonrenormalizable type for the WWγWW\gamma vertex. It is found that in this context, besides the standard model contribution, the additional contribution to fQ(q2)f_{Q}(q^2) and fA(q2)f_{A}(q^2) (fQOW(q2)f_{Q}^{O_W}(q^2) and fAOW(q2)f_{A}^{O_W}(q^2), respectively) are gauge independent and finite functions of q2q^2 after adopting a renormalization scheme. These form factors, fQOW(q2)f_{Q}^{O_W}(q^2) and fAOW(q2)f_{A}^{O_W}(q^2), get contribution at the one loop level only from the proper neutrino electromagnetic vertex. Besides, the relation fQeff(q2)=q2fAeff(q2)f_{Q}^{eff}(q^2)=q^2f_{A}^{eff}(q^2) (fQeff(q2)=fQSM(q2)+fQOW(q2)f_{Q}^{eff}(q^2)=f_{Q}^{SM}(q^2)+f_{Q}^{O_W}(q^2), fAeff(q2)=fASM(q2)+fAOW(q2)f_{A}^{eff}(q^2)=f_{A}^{SM}(q^2)+f_{A}^{O_W}(q^2)) is still fulfilled and hence the relation aνeff=eff/6a_{\nu}^{eff} = ^{eff} /6 (aνeff=aνSM+aνOWa_{\nu}^{eff} = a_{\nu}^{SM}+ a_{\nu}^{O_W}, eff=SM+<rν2>OW ^{eff} = ^{SM}+< r^2_{\nu} > ^{O_W})is gotten, just as in the SM. Using the experimental constraint on the anomalous WWγWW\gamma vertex, a value for the additional contribution to the charge radius of |^{O_W}| \lsim 10^{-34} cm^2 is obtained, which is one order of magnitude lower than the SM value.Comment: 9 pages, 3 figure

    Bound - states for truncated Coulomb potentials

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    The pseudoperturbative shifted - ll expansion technique PSLET is generalized for states with arbitrary number of nodal zeros. Bound- states energy eigenvalues for two truncated coulombic potentials are calculated using PSLET. In contrast with shifted large-N expansion technique, PSLET results compare excellently with those from direct numerical integration.Comment: TEX file, 22 pages. To appear in J. Phys. A: Math. & Ge

    T-violation in Kμ3K_{\mu3} decay in a general two-Higgs doublet model

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    We calculate the transverse muon polarization in the Kμ3+K^+_{\mu3} process arising from the Yukawa couplings of charged Higgs boson in a general two-Higgs doublet model where spontaneous violation of CP is presentComment: 6 pages, latex, accepted for publication in Phys. Rev.

    Optical-Model Description of Time-Reversal Violation

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    A time-reversal-violating spin-correlation coefficient in the total cross section for polarized neutrons incident on a tensor rank-2 polarized target is calculated by assuming a time-reversal-noninvariant, parity-conserving ``five-fold" interaction in the neutron-nucleus optical potential. Results are presented for the system n+165Hon + {^{165}{\rm Ho}} for neutron incident energies covering the range 1--20 MeV. From existing experimental bounds, a strength of 2±102 \pm 10 keV is deduced for the real and imaginary parts of the five-fold term, which implies an upper bound of order 10410^{-4} on the relative TT-odd strength when compared to the central real optical potential.Comment: 11 pages (Revtex

    On the Dalitz Plot Approach in Non-leptonic Charm Meson Decays

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    We claim that the non-resonant contribution to non-leptonic charm meson decays may not be constant in the phase space of the reaction. We argue that this can be relevant for any weak reaction. We discuss in detail the decay D+Kπ+π+D^+ \to K^- \pi^+ \pi^+.Comment: Version accepted for publication in Physical Review Letters. 9 pages, Latex, including 2 figure

    Equivalence Theorems for Pseudoscalar Coupling

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    By a unitary transformation a rigorous equivalence theorem is established for the pseudoscalar coupling of pseudoscalar mesons (neutral and charged) to a second-quantized nucleon field. By the transformation the linear pseudoscalar coupling is eliminated in favor of a nonlinear pseudovector coupling term together with other terms. Among these is a term corresponding to a variation of the effective rest mass of the nucleons with position through its dependence on the meson potentials. The question of the connection of the nonlinear pseudovector coupling with heuristic proposals that such a coupling may account for the saturation of nuclear forces and the independence of single nucleon motions in nuclei is briefly discussed. The new representation of the Hamiltonian may have particular value in constructing a strong coupling theory of pseudoscalar coupled meson fields. Some theorems on a class of unitary transformations of which the present transformation is an example are stated and proved in an appendix.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86126/1/PhysRev.87.1061-RKO.pd

    Evaluation of the Impacts of Biomass Burning Aerosols on the NASA GEOS Sub-Seasonal Climate Forecasts

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    Emission sources of trace gases and aerosol particles in the South American (SA)and African (Af) continents have a strong seasonal and space variability associated with the extensive vegetation fires activities. In both continents, during the austral winter, the fires affect mainly tropical forest and savannah-type biomes and are mostly associated with deforestation and agricultural/pasture land management. Smoke aerosol particles, on average, contribute to at least 90% of the total aerosol optical depth (AOD) in the visible spectrum in the case of the South America regional smoke. Smoke aerosols also act as cloud condensation nuclei affecting cloud microphysics properties and therefore, changing the radiation budget, hydrological cycle and global circulation patterns over disturbed areas (Kaufman, 1995; Rosenfeld, 1999; Andreae,et al., 2004; Koren et al., 2004, Zhang, 2008; Ott et al., 2010; Randles et al., 2013). This study aims to evaluate and quantify the impact of including a comprehensive emission field of biomass burning aerosol on the performance of a seasonal climate forecast system, not only regarding the AOD itself but mainly on the meteorological state variable (e.g., precipitation and temperature). To address the questions put above, we designed two numerical experiments: 1- named"AERO_CTL" which applies the Quick Fire Emissions Dataset (QFED) emissions estimated with intra-diurnal variation (hereafter, BBE), and 2- named "AERO_CLM" where the sourcee mission is based on a climatology of the QFED emissions, with only monthly variation(hereafter, BBCLIM). Hindcast simulations were produced using the Goddard Earth ObservingSystem global circulation model, version 5, sub-seasonal to seasonal (GEOS5-S2S) system with a nominal spatial resolution of 56km (Rienecker et al., 2008). In both experiments, the aerosol feedbacks from cloud developments and radiation interactions were accounted. The two experiments consisted of 4 members each and ran from June to November spanning over the years 2000 to 2015. Model performance was evaluated by calculating statistical metrics on the mean area of SA and Af. Our results demonstrated that the skill model in predicting AOD is significantly improve when BBE source emission is applied over SA, but not over the Afcontinent. Over SA, the correlation between the AERO_CTL model configuration and MERRA-2 is 0.93 (R2= 0.86, RMS=0.02, BIAS=0.01), while the AERO_CLM model presents a value of0.81 (R2= 0.65, RMS=0.04, BIAS=0.06). However, the AERO_CTL experiment better represents the inter-annual variability of the AOS in both regions. The gain of the skill in predicting the AOD by the AERO_CTL experiment is also seen in some meteorological variables. We observed an increase in the model skill in predicting the 2-meter temperature and precipitation of up to 0.3 for the AERO_CTL experiment in comparison to the AERO_CLM. AERO_CLM. According to the analyzed hindcast, we inferred that representing the BBE more realistically implies in a significant gain of skills in the seasonal climate forecasting over SA and Af continents

    Baryon and Lepton Number Assignment in E6E_6 Models

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    In E6E_6 models there are new particles whose baryon number is not uniquely assigned. We point out that the baryon and lepton number assignment to these particles can change the baryogenesis scenario significantly. We consider left-right symmetric extension of the standard model in which (BL)(B-L) quantum number is gauged. The identification of (BL)(B-L) with a generator of E6E_6 is used to define the baryon and lepton numbers for the exotic particles in a way that the electroweak baryon and lepton number anomaly corresponding to the SU(2)LSU(2)_L group vanishes, {\it i.e.}, there is no non-perturbative baryon or lepton number violation during the electroweak phase transition. We study some consequences of the new assignment.Comment: 14 pages, LaTeX file, 1 submitted Figure file(.eps

    Possibility between earthquake and explosion seismogram differentiation by discrete stochastic non-Markov processes and local Hurst exponent analysis

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    The basic purpose of the paper is to draw the attention of researchers to new possibilities of differentiation of similar signals having different nature. One of examples of such kind of signals is presented by seismograms containing recordings of earthquakes (EQ's) and technogenic explosions (TE's). We propose here a discrete stochastic model for possible solution of a problem of strong EQ's forecasting and differentiation of TE's from the weak EQ's. Theoretical analysis is performed by two independent methods: with the use of statistical theory of discrete non-Markov stochastic processes (Phys. Rev. E62,6178 (2000)) and the local Hurst exponent. Time recordings of seismic signals of the first four dynamic orthogonal collective variables, six various plane of phase portrait of four dimensional phase space of orthogonal variables and the local Hurst exponent have been calculated for the dynamic analysis of the earth states. The approaches, permitting to obtain an algorithm of strong EQ's forecasting and to differentiate TE's from weak EQ's, have been developed.Comment: REVTEX +12 ps and jpg figures. Accepted for publication in Phys. Rev. E, December 200
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