Physical Sciences and Mathematics | Open Access Articles

Investigations Into Free Tropospheric New Particle Formation In The Central Canadian Arctic During The Winter/Spring Transition As Part Of Topse, R J. Weber, D A. Orsini, B Wang, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, R L. Mauldin, E Kosciuch, C A. Cantrell, Fred Eisele

Earth Sciences

In this paper, we investigate the role of in situ new particle production in the central Canadian sub-Arctic and Arctic as part of the TOPSE experiment. Airborne measurements conducted primarily in the free troposphere were made from 50° to 90°W longitude and 60° to 85°N latitude during the period from February to May 2000. Data pertinent to this paper include 3–4 nm diameter (Dp) particles, ultrafine condensation nuclei (Dp > 3 nm), fine particles (0.2 < Dp < 3 μm), and the possible nucleation precursor, sulfuric acid, and its precursor, sulfur dioxide. For data averaged over this period, most species showed little evidence for a latitudinal trend. Fine aerosol number concentrations, however, showed a slight increase with latitude. The evolution of various species concentrations over the period of the study show that fine particles also had a consistent temporal trend, increasing at all altitudes from February to May, whereas sulfur dioxide at the surface tended to peak in late March. Ultrafine condensation nuclei and 3–4 nm particles showed no temporal trends. Little evidence for in situ new particle production was observed during the study, except for one atypical event where SO₂concentrations were 3.5 ppbv, 2 orders of magnitude higher than typical levels. This paper cannot address the question of whether the observed condensation nuclei were …

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Ozone Depletion Events Observed In The High Latitude Surface Layer During The Topse Aircraft Program, Brian Ridley, Elliot Atlas, D Montzka, Edward V. Browell, C A. Cantrell, D R. Blake, N J. Blake, L Cinquini, Michael T. Coffey, L K. Emmons, Ronald C. Cohen, Russell J. Deyoung, Jack E. Dibb, Fred Eisele, F Flocke, A Fried, F E. Grahek, William B. Grant, Jonathan Hair, James W. Hannigan, B J. Heikes, Barry Lefer, R L. Mauldin, Jennie Moody, R E. Shetter, J Snow, R. Talbot, J A. Thornton, J Walega, Andrew Weinheimer, B Wert, Anthony Wimmers

Earth Sciences

During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) aircraft program, ozone depletion events (ODEs) in the high latitude surface layer were investigated using lidar and in situ instruments. Flight legs of 100 km or longer distance were flown 32 times at 30 m altitude over a variety of regions north of 58° between early February and late May 2000. ODEs were found on each flight over the Arctic Ocean but their occurrence was rare at more southern latitudes. However, large area events with depletion to over 2 km altitude in one case were found as far south as …

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Seasonal Distributions Of Fine Aerosol Sulfate In The North American Arctic Basin During Topse, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, Barry Lefer

Earth Sciences

We used the mist chamber/ion chromatography technique to quantify fine aerosol SO₄⁼(<2.7 μm) in the Arctic during the Tropospheric Ozone Production about the Spring Equinox Experiment (TOPSE) with about 2.5 min time resolution. Our effective sample area ranged from 50° to 86°N and 53° to 100°W. The seasonal evolution of fine aerosol sulfate in the Arctic troposphere during TOPSE was consistent with the phenomenon of Arctic haze. Arctic haze has been attributed to pollution from sources in the Arctic and pollution transported meridionally along stable isentropes into the Arctic in geographically broad but vertically narrow bands. These layers became more prevalent at higher altitudes as the season progressed toward summer, and the relevant isentropes are not held so close to the surface. Mean fine particle SO₄⁼ mixing ratios during TOPSE in February below 1000 m were elevated (112 pptv) and highly variable (between 28 and 290 pptv) but were significantly lower at higher altitudes (about 40 pptv). As the season progressed, elevated mixing ratios and higher variability were observed at higher altitudes, up to 7 km. In May, mixing ratios at the lowest altitudes declined but still remained higher than in February at all altitudes. The high variability in our measurements likely reflects the vertical heterogeneity of the wintertime …

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Steady State Free Radical Budgets And Ozone Photochemistry During Topse, C A. Cantrell, Lee Mauldin, M Zondlo, Fred Eisele, E Kosciuch, R E. Shetter, Barry Lefer, S R. Hall, T L. Campos, Brian Ridley, J Walega, A Fried, B Wert, F Flocke, Andrew Weinheimer, James W. Hannigan, Michael T. Coffey, Elliot Atlas, S Stephens, B J. Heikes, J Snow, D R. Blake, N J. Blake, A Katzenstein, J Lopez, Edward V. Browell, Jack E. Dibb, Eric Scheuer, Garry Seid, R. Talbot

Earth Sciences

A steady state model, constrained by a number of measured quantities, was used to derive peroxy radical levels for the conditions of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign. The analysis is made using data collected aboard the NCAR/NSF C-130 aircraft from February through May 2000 at latitudes from 40° to 85°N, and at altitudes from the surface to 7.6 km. HO₂ + RO₂ radical concentrations were measured during the experiment, which are compared with model results over the domain of the study showing good agreement on the average. Average measurement/model ratios are 1.04 (σ …

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Springtime Photochemistry At Northern Mid And High Latitudes, Yuhang Wang, Brian Ridley, A Fried, C A. Cantrell, D D. Davis, Gao Chen, J Snow, B J. Heikes, R. Talbot, Jack E. Dibb, F Flocke, Andrew Weinheimer, N J. Blake, D R. Blake, R E. Shetter, Barry Lefer, Elliot Atlas, Michael T. Coffey, J Walega, B Wert

Earth Sciences

Physical and chemical properties of the atmosphere at 0–8 km were measured during the Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiments from February to May 2000 at mid (40°–60°N) and high latitudes (60°–80°N). The observations were analyzed using a diel steady state box model to examine HO_x and O₃ photochemistry during the spring transition period. The radical chemistry is driven primarily by photolysis of O₃ and the subsequent reaction of O(¹D) and H₂O, the rate of which increases rapidly during spring. Unlike in other tropospheric experiments, observed H₂O_{2 …}

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Effect Of Sulfate Aerosol On Tropospheric Nox And Ozone Budgets: Model Simulations And Topse Evidence, Xuexi Tie, L K. Emmons, Larry Horowitz, Guy Brasseur, Brian Ridley, Elliot Atlas, Craig Stround, Peter Hess, Andrzej Klonecki, Sasha Madronich, R. Talbot, Jack E. Dibb

Earth Sciences

The distributions of NO_x and O₃ are analyzed during TOPSE (Tropospheric Ozone Production about the Spring Equinox). In this study these data are compared with the calculations of a global chemical/transport model (Model for OZone And Related chemical Tracers (MOZART)). Specifically, the effect that hydrolysis of N₂O₅ on sulfate aerosols has on tropospheric NO_x and O₃ budgets is studied. The results show that without this heterogeneous reaction, the model significantly overestimates NO_x concentrations at high latitudes of the Northern Hemisphere (NH) in winter and spring in comparison to the observations during TOPSE; …

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Tunable Diode Laser Measurements Of Formaldehyde During The Topse 2000 Study: Distributions, Trends, And Model Comparisons, A Fried, Yuhang Wang, C A. Cantrell, B Wert, J Walega, Brian Ridley, Elliot Atlas, R E. Shetter, Barry Lefer, Michael T. Coffey, James W. Hannigan, D R. Blake, N J. Blake, Simone Meinardi, R. Talbot, Jack E. Dibb, Eric Scheuer, Oliver Wingenter, J Snow, B J. Heikes, Dieter Ehhalt

Earth Sciences

Airborne measurements of formaldehyde (CH₂O) were acquired employing tunable diode laser absorption spectroscopy (TDLAS) during the 2000 Tropospheric Ozone Production About the Spring Equinox (TOPSE) study. This study consisted of seven deployments spanning the time period from 4 February to 23 May 2000 and covered a wide latitudinal band from 40°N to 85°N. The median measured CH₂O concentrations, with a few exceptions, did not show any clear temporal trends from February to May in each of five altitude and three latitude bins examined. Detailed measurement–model comparisons were carried out using a variety of approaches employing two …

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Optically Stimulated Luminescence Dating Supports Central Arctic Ocean Cm-Scale Sedimentation Rates, Martin Jakobsson, Jan Backman, Andrew Murray, Reidar Lovlie

Center for Coastal and Ocean Mapping

This paper presents new results from Optically Stimulated Luminescence (OSL) dating on a sediment core raised from the crest of the Lomonosov Ridge in the central Arctic Ocean. There has been much debate about dating sediment cores from the central Arctic Ocean and by using an independent absolute dating technique we aim to test whether or not relatively fast, cm-scale/ka, sedimentation rates were typical of Arctic’s Pleistocene depositional mode. On the basis of mainly paleomagnetic reversal stratigraphy, many previous studies suggest mm-scale/ka sedimentation rates. A common feature in these studies is that the first down core paleomagnetic negative inclination is …

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Automatic Statistical Processing Of Multibeam Echosounder Data, Brian R. Calder

Center for Coastal and Ocean Mapping

This paper presents the CUBE (Combined Uncertainty and Bathymetry Estimator) algorithm. Our aim is to take advantage of statistical redundancy in dense Multibeam Echosounder data to identify outliers while tracking the uncertainty associated with the estimates that we make of the true depth in the survey area. We recognise that a completely automatic system is improbable, but propose that significant benefits can still be had if we can automatically process good quality data, and highlight areas that probably need further attention. We outline CUBE and its associated support structures, and apply it to a dataset from Woods Hole, MA, USA. …

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Ozone, Aerosol, Potential Vorticity, And Trace Gas Trends Observed At High-Latitudes Over North America From February To May 2000, Edward V. Browell, Jonathan Hair, Carolyn Butler, William B. Grant, Russell J. Deyoung, Marta Fenn, Vincent G. Brackett, Marian B. Clayton, Lorraine A. Brasseur, David B. Harper, Brian Ridley, Andrzej Klonecki, Peter Hess, L K. Emmons, Xuexi Tie, Elliot Atlas, C A. Cantrell, Anthony Wimmers, D R. Blake, Michael T. Coffey, James W. Hannigan, Jack E. Dibb, R. Talbot, F Flocke, Andrew Weinheimer, A Fried, B Wert, J Snow, Barry Lefer

Earth Sciences

Ozone (O₃) and aerosol scattering ratio profiles were obtained from airborne lidar measurements on thirty-eight flights over seven deployments covering the latitudes of 40°–85°N between 4 February and 23 May 2000 as part of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) field experiment. Each deployment started from Broomfield, Colorado, with bases in Churchill, Canada, and on most deployments, Thule Air Base, Greenland. Nadir and zenith lidar O₃ measurements were combined with in situ O₃measurements to produce vertically continuous O₃ profiles from near the surface to above the tropopause. Potential vorticity (PV) distributions …

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A World Class Ecdis Laboratory, Darrell H. Smith, Lee Alexander

Center for Coastal and Ocean Mapping

No abstract provided.

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Seafloor Segmentation Based On Bathymetric Measurements From Multibeam Echosounders Data, Yuri Rzhanov, Randy G. Cutter Jr., Larry A. Mayer

Center for Coastal and Ocean Mapping

Bathymetric data depicts the geomorphology of the seabottom and allows characterization of spatial distributions of apparent benthic habitats. The variability of seafloor topography can be defined as a texture. This prompts for the application of well developed image processing techniques for automatic delineation of regions with clucially different physiographic characteristics. In the present paper histograms of biologically motivated invariant image attributes are used for characterization of local geomorphological feahires. This technique can be naturally applied in a range of spatial scales. Local feature vectors are then submitted to a procedure which divides the set into a number of clusters each …

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Mapping And Characterizing Subtidal Oyster Reefs Using Acoustic Techniques, Underwater Videography And Quadrat Counts, Raymond E. Grizzle, J R. Adams, Semme J. Dijkstra, Brian Smith, R W. Ward

Center for Coastal and Ocean Mapping

Populations of the eastern oyster Crassostrea virginica have been in long-term decline in most areas. A major hindrance to effective oyster management has been lack of a methodology for accurately and economically obtaining data on their distribution and abundance patterns. Here, we describe early results from studies aimed at development of a mapping and monitoring protocol involving acoustic techniques, underwater videography, and destructive sampling (excavated quadrats). Two subtidal reefs in Great Bay, New Hampshire, were mapped with side-scan sonar and with videography by systematically imaging multiple sampling cells in a grid covering the same areas. A single deployment was made …

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The Grounding Of An Ice Shelf In The Central Arctic Ocean: A Modeling Experiment, Martin Jakobsson, M Siegert, Mark Paton

Center for Coastal and Ocean Mapping

A numerical ice sheet model was used in a first test towards evaluating the hypothesis that, during a period of large-scale glaciation, an ice shelf emanating from the Barents/Kara Seas grounded across parts of the Lomonosov Ridge to a depth of around 1000 m below present sea level (Jakobsson, 1999; Polyak et al., 2001). Despite that we not include complex ice shelf physics or grounding line mechanics in our model and treat the process of marine melting in a simple manner, our experiments are the necessary first steps toward providing a comprehensive reconstruction of the former ice-sheet/ice-shelf system in the …

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Full-Text Articles in Physical Sciences and Mathematics

Investigations Into Free Tropospheric New Particle Formation In The Central Canadian Arctic During The Winter/Spring Transition As Part Of Topse, R J. Weber, D A. Orsini, B Wang, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, R L. Mauldin, E Kosciuch, C A. Cantrell, Fred Eisele

Earth Sciences

Earth Sciences

Seasonal Distributions Of Fine Aerosol Sulfate In The North American Arctic Basin During Topse, Eric Scheuer, R. Talbot, Jack E. Dibb, Garry Seid, Linsey J. Debell, Barry Lefer

Earth Sciences

Earth Sciences

Earth Sciences

Effect Of Sulfate Aerosol On Tropospheric Nox And Ozone Budgets: Model Simulations And Topse Evidence, Xuexi Tie, L K. Emmons, Larry Horowitz, Guy Brasseur, Brian Ridley, Elliot Atlas, Craig Stround, Peter Hess, Andrzej Klonecki, Sasha Madronich, R. Talbot, Jack E. Dibb

Earth Sciences

Earth Sciences

Optically Stimulated Luminescence Dating Supports Central Arctic Ocean Cm-Scale Sedimentation Rates, Martin Jakobsson, Jan Backman, Andrew Murray, Reidar Lovlie

Center for Coastal and Ocean Mapping

Automatic Statistical Processing Of Multibeam Echosounder Data, Brian R. Calder

Center for Coastal and Ocean Mapping

Earth Sciences

A World Class Ecdis Laboratory, Darrell H. Smith, Lee Alexander

Center for Coastal and Ocean Mapping

Seafloor Segmentation Based On Bathymetric Measurements From Multibeam Echosounders Data, Yuri Rzhanov, Randy G. Cutter Jr., Larry A. Mayer

Center for Coastal and Ocean Mapping

Mapping And Characterizing Subtidal Oyster Reefs Using Acoustic Techniques, Underwater Videography And Quadrat Counts, Raymond E. Grizzle, J R. Adams, Semme J. Dijkstra, Brian Smith, R W. Ward

Center for Coastal and Ocean Mapping

The Grounding Of An Ice Shelf In The Central Arctic Ocean: A Modeling Experiment, Martin Jakobsson, M Siegert, Mark Paton

Center for Coastal and Ocean Mapping