Physical Sciences and Mathematics Commons^™

Comparing The Model-Simulated Global Warming Signal To Observations Using Empirical Estimates Of Unforced Noise, Patrick T. Brown, Wenhong Li, Eugene C. Cordero, Steven A. Mauget

Eugene C. Cordero

The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface …

Quantifying The Basal Conditions Of A Mountain Glacier Using A Targeted Full-Waveform Inversion: Bench Glacier, Alaska, Usa, E. Babcock, J. Bradford

John H. Bradford

Glacier dynamics are inextricably linked to the basal conditions of glaciers. Seismic reflection methods can image the glacier bed under certain conditions. However, where a seismically thin layer of material is present at the bed, traditional analyses may fail to fully characterize bed properties. We use a targeted full-waveform inversion algorithm to quantify the basal-layer parameters of a mountain glacier: thickness (d), P-wave velocity (α) and density (ρ). We simultaneously invert for the seismic quality factor (Q) of the bulk glacier ice. The inversion seeks to minimize the difference between the data and a one-dimensional reflectivity algorithm using a gradient-based …

Optimal Ranking Regime Analysis Of Intra- To Multidecadal U.S. Climate Variability. Part I: Temperature, Eugene C. Cordero, Steven A. Mauget

Eugene C. Cordero

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 …

Optimal Ranking Regime Analysis Of Intra- To Multidecadal U.S. Climate Variability. Part Ii: Precipitation And Streamflow, Steven A. Mauget, Eugene C. Cordero

Eugene C. Cordero

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 …

Calculating Ellipse Overlap Areas, Gary Hughes, Mohcine Chraibi

Gary B. Hughes

We present an approach for finding the overlap area between two ellipses that does not rely on proxy curves. The Gauss-Green formula is used to determine a segment area between two points on an ellipse. Overlap between two ellipses is calculated by combining the areas of appropriate segments and polygons in each ellipse. For four of the ten possible orientations of two ellipses, the method requires numerical determination of transverse intersection points. Approximate intersection points can be determined by solving the two implicit ellipse equations simultaneously. Alternative approaches for finding transverse intersection points are available using tools from algebraic geometry, …

Precise Radial Velocities Of Giant Stars V. A Brown Dwarf And A Planet Orbiting The K Giant Stars Tau Geminorum And 91 Aquarii, David Mitchell

David Mitchell

Aims. We aim to detect and characterize substellar companions to K giant stars to further our knowledge of planet formation and

stellar evolution of intermediate-mass stars.

Methods. For more than a decade we have used Doppler spectroscopy to acquire high-precision radial velocity measurements of

K giant stars. All data for this survey were taken at Lick Observatory. Our survey includes 373 G and K giants. Radial velocity data

showing periodic variations were fitted with Keplerian orbits using a χ2 minimization technique.

Results. We report the presence of two substellar companions to the K giant stars τ Gem and 91 Aqr. …

Results From An Extremely Sensitive Rayleigh-Scatter Lidar, Leda Sox, Vincent B. Wickwar

Leda Sox

Rayleigh-Scatter lidar systems effectively use remote sensing techniques to continuously measure atmospheric regions, such as the mesosphere (45-100km) where in situ measurements are rarely possible. The Rayleigh lidar located at the Atmospheric Lidar Observatory (ALO) on the Utah State campus is currently undergoing upgrades to make it the most sensitive of its kind. Here, the important components of these upgrades and how they will effect the study of a particular atmospheric phenomena, atmospheric gravity waves, will be discussed. We will also summarize what has been done to the system during this year to bring us to the threshold of initial …

Evaluating Modeled Intra- To Multidecadal Climate Variability Using Running Mann–Whitney Z Statistics, Steven A. Mauget, Eugene C. Cordero, Patrick T. Brown

Eugene C. Cordero

An analysis method previously used to detect observed intra- to multidecadal (IMD) climate regimes was adapted to compare observed and modeled IMD climate variations. Pending the availability of the more appropriate phase 5 Coupled Model Intercomparison Project (CMIP-5) simulations, the method is demonstrated using CMIP-3 model simulations. Although the CMIP-3 experimental design will almost certainly prevent these model runs from reproducing features of historical IMD climate variability, these simulations allow for the demonstration of the method and illustrate how the models and observations disagree. This method samples a time series’s data rankings over moving time windows, converts those ranking sets …

Finite-State Markov Chains Obey Benford’S Law, Arno Berger, Theodore P. Hill, Bahar Kaynar, Ad Ridder

Theodore P. Hill

A sequence of real numbers (xn) is Benford if the significands, i.e., the fraction parts in the floating-point representation of (xn), are distributed logarithmically. Similarly, a discrete-time irreducible and aperiodic finite-state Markov chain with transition probability matrix P and limiting matrix P* is Benford if every component of both sequences of matrices (Pn−P*) and (Pn+1−Pn) is Benford or eventually zero. Using recent tools that established Benford behavior for finite-dimensional linear maps, via the classical theories of uniform distribution modulo 1 and Perron–Frobenius, this paper derives a simple sufficient condition (“nonresonance”) guaranteeing that P, or the Markov chain associated with it, …

Benford’S Law Strikes Back: No Simple Explanation In Sight For Mathematical Gem, Arno Berger, Theodore P. Hill

Theodore P. Hill

No abstract provided.

Projection Of Diffraction Patterns For Use In Cold-Neutral-Atom Trapping, Katharina Gillen-Christandl, Glen D. Gillen

Glen Gillen

Scalar diffraction theory is combined with beam-propagation techniques to investigate the projection of near-field diffraction patterns to spatial locations away from the aperture for use in optically trapping cold neutral alkali-metal atoms. Calculations show that intensity distributions with localized bright and dark spots usually found within a millimeter of the diffracting aperture can be projected to a region free from optical components such as a cloud of cold atoms within a vacuum chamber. Calculations also predict that the critical properties of the optical dipole atom traps are not only maintained for the projected intensity patterns but also can be manipulated …

Projection Of Diffraction Patterns For Use In Cold-Neutral-Atom Trapping, Katharina Gillen-Christandl, Glen D. Gillen

Katharina Gillen

Scalar diffraction theory is combined with beam-propagation techniques to investigate the projection of near-field diffraction patterns to spatial locations away from the aperture for use in optically trapping cold neutral alkali-metal atoms. Calculations show that intensity distributions with localized bright and dark spots usually found within a millimeter of the diffracting aperture can be projected to a region free from optical components such as a cloud of cold atoms within a vacuum chamber. Calculations also predict that the critical properties of the optical dipole atom traps are not only maintained for the projected intensity patterns but also can be manipulated …

Chemistry–Climate Model Simulations Of Twenty-First Century Stratospheric Climate And Circulation Changes, Neal Butchart, I. Cionni, V. Eyring, T. G. Shepherd, D. W. Waugh, H. Akiyoshi, J. Austin, C. Brühl, M. P. Chipperfield, Eugene C. Cordero, M. Dameris, R. Deckert, S. Dhomse, S. M. Frith, R. R. Garcia, A. Gettelman, M. A. Giorgetta, D. E. Kinnison, F. Li, E. Mancini, S. Pawson, G. Pitari, D. A. Plummer, E. Rozanov, F. Sassi, J. F. Scinocca, K. Shibata, B. Steil, W. Tian

Eugene C. Cordero

The response of stratospheric climate and circulation to increasing amounts of greenhouse gases (GHGs) and ozone recovery in the twenty-first century is analyzed in simulations of 11 chemistry–climate models using near-identical forcings and experimental setup. In addition to an overall global cooling of the stratosphere in the simulations (0.59 ± 0.07 K decade⁻¹ at 10 hPa), ozone recovery causes a warming of the Southern Hemisphere polar lower stratosphere in summer with enhanced cooling above. The rate of warming correlates with the rate of ozone recovery projected by the models and, on average, changes from 0.8 to 0.48 K decade …

Climate Change Education And The Ecological Footprint, Eugene C. Cordero, Anne Marie Todd, Diana Abellera

Eugene C. Cordero

Global warming has become one of the most important scientific, political, and social issues of our era. In designing an effective mitigation strategy, it is clear that public education must play an important role. This study looks at various components of climate change literacy within a cohort of university students and investigates the impact of action-oriented learning on student understanding. Results from questionnaires given to primarily nonscience students enrolled in weather and climate courses are used to examine student knowledge of climate change. In agreement with prior research, this study finds that signif icant student misconceptions exist regarding the causes …

Bioluminescence In A Complex Coastal Environment: 1. Temporal Dynamics Of Nighttime Water-Leaving Radiance, Mark A. Moline, Matthew J. Oliver, Curtis D. Mobley, Lydia Sundman, Thomas J. Bensky, Trisha Bergmann, W. Paul Bissett, James Case, Erika H. Raymond, Oscar M.E. Schofield

Mark A. Moline

Nighttime water-leaving radiance is a function of the depth-dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one-dimensional radiative transfer model to solve for spectral bioluminescence water-leaving radiance from prescribed depths of the water column. Variation in the water-leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a >90 nm shift in the peak water-leaving radiance from blue (~474 nm) …

Bioluminescence In A Complex Coastal Environment: 1. Temporal Dynamics Of Nighttime Water-Leaving Radiance, Mark A. Moline, Matthew J. Oliver, Curtis D. Mobley, Lydia Sundman, Thomas J. Bensky, Trisha Bergmann, W. Paul Bissett, James Case, Erika H. Raymond, Oscar M.E. Schofield

Thomas Bensky

Nighttime water-leaving radiance is a function of the depth-dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one-dimensional radiative transfer model to solve for spectral bioluminescence water-leaving radiance from prescribed depths of the water column. Variation in the water-leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a >90 nm shift in the peak water-leaving radiance from blue (~474 nm) …

Multimodel Projections Of Stratospheric Ozone In The 21st Century, V. Eyring, D. W. Waugh, G. E. Bodeker, Eugene C. Cordero, H. Akiyoshi, J. Austin, S. R. Beagley, B. A. Boville, P. Braesicke, C. Brühl, N. Butchart, M. P. Chipperfield, M. Dameris, R. Deckert, M. Deushi, S. M. Frith, R. R. Garcia, A. Gettelman, M. A. Giorgetta, D. E. Kinnison, E. Mancini, E. Manzini, D. R. Marsh, S. Matthes, T. Nagashima, P. A. Newman, J. E. Nielsen, S. Pawson, G. Pitari, D. A. Plummer, E. Rozanov, M. Schraner, J. F. Scinocca, K. Semeniuk, T. G. Shepherd, K. Shibata, B. Steil, R. S. Stolarski, W. Tian, M. Yoshiki

Eugene C. Cordero

[1] Simulations from eleven coupled chemistry-climate models (CCMs) employing nearly identical forcings have been used to project the evolution of stratospheric ozone throughout the 21st century. The model-to-model agreement in projected temperature trends is good, and all CCMs predict continued, global mean cooling of the stratosphere over the next 5 decades, increasing from around 0.25 K/decade at 50 hPa to around 1 K/decade at 1 hPa under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario. In general, the simulated ozone evolution is mainly determined by decreases in halogen concentrations and continued cooling of …

Stratospheric Variability And Trends In Models Used For The Ipcc Ar4, P. M. De F. Forster, Eugene Cordero

Eugene C. Cordero

Atmosphere and ocean general circulation model (AOGCM) experiments for the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) are analyzed to better understand model variability and assess the importance of various forcing mechanisms on stratospheric trends during the 20th century. While models represent the climatology of the stratosphere reasonably well in comparison with NCEP reanalysis, there are biases and large variability among models. In general, AOGCMs are cooler than NCEP throughout the stratosphere, with the largest differences in the tropics. Around half the AOGCMs have a top level beneath ~2 hPa and show a significant cold bias in their …

Assessment Of Temperature, Trace Species, And Ozone In Chemistry-Climate Model Simulations Of The Recent Past, V. Eyring, N. Butchart, D. W. Waugh, H. Akiyoshi, J. Austin, S. Bekki, G. E. Bodeker, B. A. Boville, C. Brühl, M. P. Chipperfield, E. Cordero, M. Dameris, M. Deushi, V. E. Fioletov, S. M. Frith, R. R. Garcia, A. Gettelman, M. A. Giorgetta, V. Grewe, L. Jourdain, D. E. Kinnison, E. Mancini, E. Manzini, M. Marchand, D. R. Marsh, T. Nagashima, P. A. Newman, J. E. Nielsen, S. Pawson, G. Pitari, D. A. Plummer, E. Rozanov, M. Schraner, T. G. Shepherd, K. Shibata, R. S. Stolarski, H. Struthers, W. Tian, M. Yoshiki

Eugene C. Cordero

[1] Simulations of the stratosphere from thirteen coupled chemistry-climate models (CCMs) are evaluated to provide guidance for the interpretation of ozone predictions made by the same CCMs. The focus of the evaluation is on how well the fields and processes that are important for determining the ozone distribution are represented in the simulations of the recent past. The core period of the evaluation is from 1980 to 1999 but long-term trends are compared for an extended period (1960–2004). Comparisons of polar high-latitude temperatures show that most CCMs have only small biases in the Northern Hemisphere in winter and spring, but …

A New Pathway For Communicating The 11-Year Solar Cycle Signal To The Qbo, Eugene C. Cordero, Terrence R. Nathan

Eugene C. Cordero

[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 …

Microgravity Studies Of Aggregation In Particulate Clouds, Todd B. Sauke, J. R. Marshall, J. N. Cuzzi

Todd B. Sauke

Aggregation in clouds of submillimeter quartz and volcanic ash particles was studied in microgravity. Particle clouds generated by pulses of air immediately formed electrostatic filamentary aggregates upon cessation of air turbulence. Manual agitation of experiment chambers produced cm-size loose grain clusters which voraciously scavenged free-floating material in their vicinity. A dipole model accounts for these observations. Experimental results have ramifications for the behavior of natural cloud systems and primary accretion of solids in the early solar nebula.

Removing Excess Topology From Isosurfaces, Zoë J. Wood, Hugues Hoppe, Mathieu Desbrun, Peter Shröder

Zoë Wood

Many high-resolution surfaces are created through isosurface extraction from volumetric representations, obtained by 3D photography, CT, or MRI. Noise inherent in the acquisition process can lead to geometrical and topological errors. Reducing geometrical errors during reconstruction is well studied. However, isosurfaces often contain many topological errors in the form of tiny handles. These nearly invisible artifacts hinder subsequent operations like mesh simplification, remeshing, and parametrization. In this article we present a practical method for removing handles in an isosurface. Our algorithm makes an axis-aligned sweep through the volume to locate handles, compute their sizes, and selectively remove them. The algorithm …

An Examination Of Anomalously Low Column Ozone In The Southern Hemisphere Midlatitudes During 1997, Eugene C. Cordero, Terrence R. Nathan

Eugene C. Cordero

[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 …

Is The Ozone Hole Over Your Classroom?, Eugene Cordero

Eugene C. Cordero

First year university science students are surveyed about their understanding of the ozone layer, ozone depletion and the effect of ozone depletion on Australia. Although students seem to understand the basic function of the ozone layer, over 65% of students incorrectly believe that the ozone hole is over Australia, and over 90% of students incorrectly believe that the ozone hole is present during the summer. Together these ideas seem to explain why nearly 75% of students blame the ozone hole for Australia’s high rate of skin cancer. Survey results also indicate that students seem confused about global warming, and the …

Ozone And Tracer Transport Variations In The Summer Northern Hemisphere Stratosphere, E. C. Cordero, S. R. Kawa

Eugene C. Cordero

Constituent observations from the Upper Atmosphere Research Satellite (UARS) in combination with estimates of the residual circulation are used to examine the transport and chemical budgets of HF, CH₄ and O₃ in the summer Northern Hemisphere. Budget calculations of HF, CH₄ and O₃ show that the transport tendency due to the residual circulation increases in magnitude and is largely opposed by eddy motions through the summer months. Ozone budget analyses show that between 100 and 31 hPa, the magnitudes of the mean circulation and eddy transport terms increase through the summer months, producing tendencies that are …

The Influence Of Wave– And Zonal Mean–Ozone Feedbacks On The Quasi-Biennial Oscillation, Eugene Cordero, Terrence R. Nathan

Eugene C. Cordero

The effects of wave and zonal mean ozone heating on the evolution of the quasi-biennial oscillation (QBO) are examined using a two-dimensional mechanistic model of the equatorial stratosphere. The model atmosphere is governed by coupled equations for the zonal mean and (linear) wave fields of ozone, temperature, and wind, and is driven by specifying the amplitudes of a Kelvin wave and a Rossby–gravity wave at the lower boundary. Wave–mean flow interactions are accounted for in the model, but not wave–wave interactions.

A reference simulation (RS) of the QBO, in which ozone feedbacks are neglected, is carried out and the results …

Effects Of Planetary Wave-Breaking On The Seasonal Variation Of Total Column Ozone, Terrence R. Nathan, Eugene C. Cordero, Long Li, Donald J. Wuebbles

Eugene C. Cordero

The effects of planetary wave breaking on the seasonal variation of total column ozone are investigated using a zonally averaged chemical-radiative-transport model of the atmosphere. The planetary wave breaking effects of zonal wavenumbers k=1 and k=2 are significant in the middle latitude stratosphere during Northern Hemisphere (NH) winter, whereas only wave k=1 is important during Southern Hemisphere (SH) winter. The mixing and induced meridional circulation due to the planetary wave breaking increases the seasonal variation of total column ozone in NH (SH) middle latitudes by ∼20% (∼10%).

An Analytical Study Of Ozone Feedbacks On Kelvin And Rossby–Gravity Waves: Effects On The Qbo, Eugene Cordero, Terrence R. Nathan, Robert S. Echols

Eugene C. Cordero

An equatorial beta-plane model of the middle atmosphere is used to analytically examine the effects of radiative cooling and ozone heating on the spatial and temporal evolution of the quasi-biennial oscillation (QBO). Under the assumption that the diabatic heating is weak and the background fields of wind, temperature, and ozone are slowly varying, a perturbation analysis yields expressions describing the vertical spatial modulation of Kelvin and Rossby–gravity waves in the presence of ozone. These expressions show that wave-induced changes in the diabatic heating arising from the advection of basic-state ozone reduce the local radiative damping rate by up to 15% …

An Analysis Of Tropical Transport: Influence Of The Quasi-Biennial Oscillation, Eugene C. Cordero, S. Randolph Kawa, Mark R. Schoeberl

Eugene C. Cordero

An analysis of over 4 years of Upper Atmosphere Research Satellite (UARS) measurements of CH₄, HF, O₃, and zonal wind are used to study the influence of the quasi-biennial oscillation (QBO) on constituent transport in the tropics. At the equator, spectral analysis of the Halogen Occultation Experiment (HALOE) and Microwave Limb Sounder (MLS) observations reveals QBO signals in constituent and temperature fields at altitudes between 20 and 45 km. Between these altitudes, the location of the maximum QBO amplitude roughly corresponds with the location of the largest vertical gradient in the constituent field. Thus, at 40 …

Stable Isotope Analysis Using Tunable Diode Laser Spectroscopy, Todd Sauke, J. Becker, M. Loewenstein

Todd B. Sauke

Measurements of ratios of stable isotopes are used in such diverse fields as petroleum prospecting, medical diagnostics, and planetary exploration. The narrow emission linewidth available from tunable diode lasers permits high-resolution infrared absorption measurements of closely spaced isotopic rovibrational lines. Our dual beam spectrometer uses the sweep integration technique in a spectral region where adjacent spectral lines are of approximately equal absorbance at the expected isotopic abundances. The experimental results reported here indicate that isotopic ratios of carbon in carbon dioxide can be measured to an accuracy of better than 0.4%. This laser spectroscopic spectrometric technique offers an alternative to …