An Ozone-Modified Refractive Index for Vertically Propagating Planetary Waves

[1] An ozone-modified refractive index (OMRI) is derived for vertically propagating planetary waves using a mechanistic model that couples quasigeostrophic potential vorticity and ozone volume mixing ratio. The OMRI clarifies how wave-induced heating due to ozone photochemistry, ozone transport, and Newtonian cooling (NC) combine to affect wave propagation, attenuation, and drag on the zonal mean flow. In the photochemically controlled upper stratosphere, the wave-induced ozone heating (OH) always augments the NC, whereas in the dynamically controlled lower stratosphere, the wave-induced OH may augment or reduce the NC depending on the detailed nature of the wave vertical structure and zonal mean ozone gradients. For a basic state representative of Northern Hemisphere winter, the wave-induced OH can increase the planetary wave drag by more than a factor of two in the photochemically controlled upper stratosphere and decrease it by as much as 25% in the dynamically controlled lower stratosphere. Because the zonal mean ozone distribution appears explicitly in the OMRI, the OMRI can be used as a tool for understanding how changes in stratospheric ozone due to solar variability and chemical depletion affect stratosphere-troposphere communication

Optimal Ranking Regime Analysis of Intra- to Multidecadal U.S. Climate Variability. Part I: Temperature

The optimal ranking regime (ORR) method was used to identify intradecadal to multidecadal (IMD) time windows containing significant ranking sequences in U.S. climate division temperature data. The simplicity of the ORR procedure’s output—a time series’ most significant nonoverlapping periods of high or low rankings—makes it possible to graphically identify common temporal breakpoints and spatial patterns of IMD variability in the analyses of 102 climate division temperature series. This approach is also applied to annual Atlantic multidecadal oscillation (AMO) and Pacific decadal oscillation (PDO) climate indices, a Northern Hemisphere annual temperature (NHT) series, and divisional annual and seasonal temperature data during 1896–2012. In addition, Pearson correlations are calculated between PDO, AMO, and NHT series and the divisional temperature series. Although PDO phase seems to be an important influence on spring temperatures in the northwestern United States, eastern temperature regimes in annual, winter, summer, and fall temperatures are more coincident with cool and warm phase AMO regimes. Annual AMO values also correlate significantly with summer temperatures along the Eastern Seaboard and fall temperatures in the U.S. Southwest. Given evidence of the abrupt onset of cold winter temperatures in the eastern United States during 1957/58, possible climate mechanisms associated with the cause and duration of the eastern U.S. warming hole period—identified here as a cool temperature regime occurring between the late 1950s and late 1980s—are discussed

An Examination of Anomalously Low Column Ozone in the Southern Hemisphere Midlatitudes During 1997

[1] Observations from both ground-based and satellite instruments show record low column ozone abundance between 20°S and 40°S during 1997. The 1997 monthly averaged column ozone from the Total Ozone Mapping Spectrometer (TOMS) is up to 25 Dobson units (DU) lower than the TOMS climatological mean (1979–1996) and up to 20 DU below the previous record low values. Observations from the Halogen Occultation Experiment show that below average ozone concentrations during 1997 were confined primarily to the lower stratosphere. Residual circulation statistics calculated from the United Kingdom Meteorological Office temperature analyses indicate that circulation anomalies during 1997 can account for ∼5–10 DU/month decrease in column ozone between 20°S and 50°S. At these latitudes during 1997, structural characteristics of the ozone and residual circulation fields both suggest a connection with the equatorial quasi-biennial oscillation

Optimal Ranking Regime Analysis of Intra- to Multidecadal U.S. Climate Variability. Part II: Precipitation and Streamflow

In Part I of this paper, the optimal ranking regime (ORR) method was used to identify intradecadal to multidecadal (IMD) regimes in U.S. climate division temperature data during 1896–2012. Here, the method is used to test for annual and seasonal precipitation regimes during that same period. Water-year mean streamflow rankings at 125 U.S. Hydro-Climatic Data Network gauge stations are also evaluated during 1939–2011. The precipitation and streamflow regimes identified are compared with ORR-derived regimes in the Pacific decadal oscillation (PDO), the Atlantic multidecadal oscillation (AMO), and indices derived from gridded SST anomaly (SSTA) analysis data. Using a graphic display approach that allows for the comparison of IMD climate regimes in multiple time series, an interdecadal cycle in western precipitation is apparent after 1980, as is a similar cycle in northwestern streamflow. Before 1980, IMD regimes in northwestern streamflow and annual precipitation are in approximate antiphase with the PDO. One of the clearest IMD climate signals found in this analysis are post-1970 wet regimes in eastern U.S streamflow and annual precipitation, as well as in fall [September–November (SON)] precipitation. Pearson correlations between time series of annual and seasonal precipitation averaged over the eastern United States and SSTA analysis data show relatively extensive positive correlations between warming tropical SSTA and increasing fall precipitation. The possible Pacific and northern Atlantic roots of the recent eastern U.S. wet regime, as well as the general characteristics of U.S. climate variability in recent decades that emerge from this analysis and that of Part I, are discussed

A New Pathway for Communicating the 11-year Solar Cycle Signal to the QBO

[1] The response of the equatorial quasi-biennial oscillation (QBO) to zonal-mean ozone perturbations consistent with the 11-year solar cycle is examined using a 2 1/2 dimensional model of the tropical stratosphere. Unique to this model are wave-ozone feedbacks, which provide a new, nonlinear pathway for communicating solar variability effects to the QBO. Model simulations show that for zonal-mean ozone perturbations representative of solar maximum (minimum), the diabatic heating due to the wave-ozone feedbacks is primarily responsible for driving a slightly stronger (weaker) QBO circulation and producing a slightly shorter (longer) QBO period. These results, which are explained via an analytical analysis of the divergence of Eliassen-palm flux, are in general agreement with observations of quasi-decadal variability of the QBO

Acoustic measurement of the low-energy excitations in Nd2-xCexCuO4

The complex dynamic Young's modulus of ceramic Nd2-xCexCuO4 with x = 0, 0.05 and 0.20 has been measured from 1.5 to 100 K at frequencies of 1-10 kHz. In the undoped sample the modulus starts decreasing below ~20 K, instead of approaching a constant value as in a normal solid. The modulus minimum has been interpreted in terms of paraelastic contribution from the relaxation of the Nd^3+ 4f electrons between the levels of the ground state doublet, which is split by the interaction with the antiferromagnetically ordered Cu sublattice. The value of the splitting is found to be 0.34 meV, in excellent agreement with inelastic neutron scattering, infrared and specific heat experiments. With doping, the anomaly shifts to lower temperature and decreases in amplitude, consistently with a reduction of the local field from the Cu sublattice.Comment: 5 pages, 2 figures, submitted to Eur. Phys. J.

Hopping and clustering of oxygen vacancies in SrTiO3 by anelastic relaxation

The complex elastic compliance s11(w,T) of SrTiO3-d has been measured as a function of the O deficiency d < 0.01. The two main relaxation peaks in the absorption are identified with hopping of isolated O vacancies over a barrier of 0.60 eV and reorientation of pairs of vacancies involving a barrier of 1 eV. The pair binding energy is ~0.2 eV and indications for additional clustering, possibly into chains, is found already at d ~0.004. The anistropic component of the elastic dipole of an O vacancy is Deltalambda = 0.026.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

Obfuscation-based malware update: A comparison of manual and automated methods

Indexación: Scopus; Web of Science.This research presents a proposal of malware classification and its update based on capacity and obfuscation. This article is an extension of [4]a, and describes the procedure for malware updating, that is, to take obsolete malware that is already detectable by antiviruses, update it through obfuscation techniques and thus making it undetectable again. As the updating of malware is generally performed manually, an automatic solution is presented together with a comparison from the standpoint of cost and processing time. The automated method proved to be more reliable, fast and less intensive in the use of resources, specially in terms of antivirus analysis and malware functionality checking times.http://univagora.ro/jour/index.php/ijccc/article/view/2961/112