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895 results on '"Pfister, G."'

5. End-wall effects on the transition between Taylor vortices and spiral vortices

Author

Altmeyer, S., Hoffmann, Ch., Heise, M., Pinter, A., Lücke, M., and Pfister, G.

Subjects
Nonlinear Sciences - Pattern Formation and Solitons
Abstract

We present numerical simulations as well as experimental results concerning transitions between Taylor vortices and spiral vortices in the Taylor-Couette system with rigid, non-rotating end-walls in axial direction. As in the axial periodic case, these transitions are performed by wavy structures appearing via a secondary bifurcation out of Taylor vortices and spirals, respectively. But in the presence of rigid lids, pure spiral solutions do not occur but are substituted by primary bifurcating, stable wavy spiral structures (wSPI). Similarly to the periodic system, we found a transition from Taylor vortices to wSPI mediated by so called wavy Taylor vortices (wTVF) and, on the other hand, a transition from wSPI to TVF triggered by a propagating defect. We furthermore observed and investigated the primary bifurcation of wSPI out of basic Ekman flow., Comment: 6 figures

Published
2009
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6. A regional scale modeling analysis of aerosol and trace gas distributions over the eastern Pacific during the INTEX-B field campaign

Author

Adhikary, B., Carmichael, G. R, Kulkarni, S., Wei, C., Tang, Y., D'Allura, A., Mena-Carrasco, M., Streets, D. G, Zhang, Q., Pierce, R. B, Al-Saadi, J. A, Emmons, L. K, Pfister, G. G, Avery, M. A, Barrick, J. D, Blake, D. R, Brune, W. H, Cohen, R. C, Dibb, J. E, Fried, A., Heikes, B. G, Huey, L. G, O'Sullivan, D. W, Sachse, G. W, Shetter, R. E, Singh, H. B, Campos, T. L, Cantrell, C. A, Flocke, F. M, Dunlea, E. J, Jimenez, J. L, Weinheimer, A. J, Crounse, J. D, Wennberg, P. O, Schauer, J. J, Stone, E. A, Jaffe, D. A, and Reidmiller, D. R

Subjects
long-range transport, north-america, transpacific transport, pollution transport, asian aerosols, air-pollution, mineral dust, organic mass, emissions, aircraft
Abstract

The Sulfur Transport and dEposition Model (STEM) is applied to the analysis of observations obtained during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), conducted over the eastern Pacific Ocean during spring 2006. Predicted trace gas and aerosol distributions over the Pacific are presented and discussed in terms of transport and source region contributions. Trace species distributions show a strong west (high) to east (low) gradient, with the bulk of the pollutant transport over the central Pacific occurring between similar to 20 degrees N and 50 degrees N in the 2-6 km altitude range. These distributions are evaluated in the eastern Pacific by comparison with the NASA DC-8 and NSF/NCAR C-130 airborne measurements along with observations from the Mt. Bachelor (MBO) surface site. Thirty different meteorological, trace gas and aerosol parameters are compared. In general the meteorological fields are better predicted than gas phase species, which in turn are better predicted than aerosol quantities. PAN is found to be significantly overpredicted over the eastern Pacific, which is attributed to uncertainties in the chemical reaction mechanisms used in current atmospheric chemistry models in general and to the specifically high PAN production in the SAPRC-99 mechanism used in the regional model. A systematic underprediction of the elevated sulfate layer in the eastern Pacific observed by the C-130 is another issue that is identified and discussed. Results from source region tagged CO simulations are used to estimate how the different source regions around the Pacific contribute to the trace gas species distributions. During this period the largest contributions were from China and from fires in South/Southeast and North Asia. For the C-130 flights, which operated off the coast of the Northwest US, the regional CO contributions range as follows: China (35%), South/Southeast Asia fires (35%), North America anthropogenic (20%), and North Asia fires (10%). The transport of pollution into the western US is studied at MBO and a variety of events with elevated Asian dust, and periods with contributions from China and fires from both Asia and North America are discussed. The role of heterogeneous chemistry on the composition over the eastern Pacific is also studied. The impacts of heterogeneous reactions at specific times can be significant, increasing sulfate and nitrate aerosol production and reducing gas phase nitric acid levels appreciably (similar to 50%).

Published
2010

9. The Impact of Boreal Forest Fire on Climate Warming

Author

Randerson, J. T, Liu, H., Flanner, M. G, Chambers, S. D, Jin, Y., Hess, P. G, Pfister, G., Mack, M. C, Treseder, K. K, Welp, L. R, Chapin, F. S, Harden, J. W, Goulden, M. L, Lyons, E., Neff, J. C, Schuur, E. A. G, and Zender, C. S

Abstract

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 ± 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (–2.3 ± 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.

Published
2006

10. Moduli spaces of semiquasihomogeneous singularities with fixed principal part

Author

Greuel, G. -M., Hertling, C., and Pfister, G.

Subjects
Mathematics - Algebraic Geometry
Abstract

We construct coarse moduli spaces of semiquasihomogeneous hypersurface singularities with respect to right equivalence and contact equivalence. We have to fix the principal part of the semiquasihomogeneous singularities. For the moduli spaces with respect to contact equivalence we also fix the Hilbert function of the Tjurina algebra induced by the weights., Comment: 31 pages. AMSLaTeX

Published
1995

17. The Effect of Entrainment Through Atmospheric Boundary Layer Growth on Observed and Modeled Surface Ozone in the Colorado Front Range

Author

Kaser, L, Patton, E. G, Pfister, G. G, Weinheimer, A. J, Montzka, D. D, Flocke, F, Thompson, A. M, Stauffer, R. M, and Halliday, H. S

Subjects
Geophysics
Abstract

Ozone concentrations at the Earth's surface are controlled by meteorological and chemical processes and are a function of advection, entrainment, deposition, and net chemical production/loss. The relative contributions of these processes vary in time and space. Understanding the relative importance of these processes controlling surface ozone concentrations is an essential component for designing effective regulatory strategies. Here we focus on the diurnal cycle of entrainment through atmospheric boundary layer (ABL) growth in the Colorado Front Range. Aircraft soundings and surface observations collected in July/August 2014 during the DISCOVER-AQ/FRAPPÉ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality/Front Range Air Pollution and Photochemistry Éxperiment) campaigns and equivalent data simulated by a regional chemical transport model are analyzed. Entrainment through ABL growth is most important in the early morning, fumigating the surface at a rate of ~5 ppbv/h. The fumigation effect weakens near noon and changes sign to become a small dilution effect in the afternoon on the order of -1 ppbv/h. The chemical transport model WRF-Chem (Weather Research and Forecasting Model with chemistry) underestimates ozone at all altitudes during this study on the order of 10-15 ppbv. The entrainment through ABL growth is overestimated by the model in the order of 0.6-0.8 ppbv/h. This results from differences in boundary layer growth in the morning and ozone concentration jump across the ABL top in the afternoon. This implicates stronger modeled fumigation in the morning and weaker modeled dilution after 11:00 LT.

Published
2017
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18. Formation of Dynamical Structures in Axisymmetric Fluid Systems

Author

Busse, F. H., Pfister, G., Schwabe, D., Beig, R., editor, Ehlers, J., editor, Frisch, U., editor, Hepp, K., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Ojima, I., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Beiglböck, W., editor, Busse, Friedrich H., and Müller, Stefan C.

Published
1998
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22. Spatial Variability of Trace Gases During DISCOVER-AQ: Planning for Geostationary Observations of Atmospheric Composition

Author

Follette-Cook, Melanie B, Pickering, K, Crawford, J, Appel, W, Diskin, G, Fried, A, Loughner, C, Pfister, G, and Weinheimer, A

Subjects
Environment Pollution, Earth Resources And Remote Sensing
Abstract

Results from an in-depth analysis of trace gas variability in MD indicated that the variability in this region was large enough to be observable by a TEMPO-like instrument. The variability observed in MD is relatively similar to the other three campaigns with a few exceptions: CO variability in CA was much higher than in the other regions; HCHO variability in CA and CO was much lower; MD showed the lowest variability in NO2All model simulations do a reasonable job simulating O3 variability. For CO, the CACO simulations largely under over estimate the variability in the observations. The variability in HCHO is underestimated for every campaign. NO2 variability is slightly overestimated in MD, more so in CO. The TX simulation underestimates the variability in each trace gas. This is most likely due to missing emissions sources (C. Loughner, manuscript in preparation).Future Work: Where reasonable, we will use these model outputs to further explore the resolvability from space of these key trace gases using analyses of tropospheric column amounts relative to satellite precision requirements, similar to Follette-Cook et al. (2015).

Published
2015

24. The Yangtze-Hydro Project: a Chinese–German environmental program

Author

Bergmann, A., Bi, Y., Chen, L., Floehr, T., Henkelmann, B., Holbach, A., Hollert, H., Hu, W., Kranzioch, I., Klumpp, E., Küppers, S., Norra, S., Ottermanns, R., Pfister, G., Roß-Nickoll, M., Schäffer, A., Schleicher, N., Schmidt, B., Scholz-Starke, B., Schramm, K.-W., Subklew, G., Tiehm, A., Temoka, C., Wang, J., Westrich, B., Wilken, R.-D., Wolf, A., Xiang, X., and Yuan, Y.

Published
2012
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25. An evaluation of sorter induced cell stress (SICS) on peripheral blood mononuclear cells (PBMCs) after different sort conditions - are your sorted cells getting SICS?

Author

Pfister, G, Toor, SM, Sasidharan Nair, V, and Elkord, E

Abstract

Flow cytometry and fluorescence-activated cell sorting have become invaluable tools to analyze and isolate specific cell populations in a wide range of biomedical research and clinical applications. In countless approaches worldwide, scientists are using single cell analyses to better understand the significance and variation within different cellular populations, and fluorescence-activated cell sorting has become a major technique for cell isolation in both basic and clinical research. However, majority of available cell sorters are pressurized, droplet-based systems, which apply significant environmental pressure and shear stress to cells during sorting. Recently, the flow cytometry community has become increasingly aware about the potential negative effects this could have on sorted cells and the term "sorter induced cell stress" (SICS) has been proposed. However, up to date only a limited number of studies have investigated the effects of cell sorting on cell viability and function. Therefore, solid data on the effects of sheath pressure and nozzle size on survival and function of sorted cells are surprisingly rare. With this in mind, we sorted "CD4 " T-cells and "live" cells from human peripheral blood mononuclear cells (PBMCs) at different sort conditions and analyzed their quality before and after sorting in a series of assays. Here we present our findings in reference to cell viability and cell proliferation following sorting on different instruments (BD FACSAria III SORP and BD FACSJazz), utilizing different nozzle sizes (70 to 100 μm) and sheath pressure settings (20 to 70 psi). The results show no significant differences in cell viability and proliferation after the different tested sort conditions, but rather differences between individual experiments. These findings are evaluated and their potential significance in cell sorting experiments is discussed. [Abstract copyright: Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.]

Published
2020

28. Training Materials and Best Practices for Chemical Weather/Air Quality Forecasting

Author

Appel, K., Ching, J., Freitas, E., ́Garcia-Pando, C., Henze, D., Jorba, O., Keller, C., Knievel, J., Lee, P., Makar, P., Masson, V., Delle Monache, L., Saide, P., ́Del Rio, J., Sartelet, K., Sofiev, M., Stockwell, W., Tong, D., Yu, S., Zhang, Y., Zhou, C., Zilitinkevich, S., Aliaga, D., Andrade, M., Basart, S., Benedetti, A., Bocquet, M., Calmarini, S., Carmichael, G., Cope, M., da Silva, A., Duc, H., Flemming, J., Grell, G., Inness, A., Johansson, L., Kaiser, J., Karppinen, A., Kipling, Z., Martilli, A., Mills, G., Pagowski, M., Pfister, G., Ren, C., Rolph, G., Sanchez, B., Sandu, A., Sokhi, R., Zhang , Y., and Baklanov , A.

Published
2020

34. Deep brain stimulation of the subthalamic nucleus in Parkinson's disease: evaluation of active electrode contacts

Author

Hamel, W, Fietzek, U, Morsnowski, A, Schrader, B, Herzog, J, Weinert, D, Pfister, G, Muller, D, Volkmann, J, Deuschl, G, and Mehdorn, HM

Subjects
Thalamus -- Health aspects -- Research -- Methods, Dopa -- Complications and side effects -- Research, Patients -- Care and treatment -- Health aspects -- Research -- Methods, Electrodes -- Health aspects -- Research -- Methods, Magnetic resonance imaging -- Methods -- Health aspects -- Research, Parkinson's disease -- Health aspects -- Care and treatment -- Research -- Complications and side effects, Clinical neuropsychology -- Research -- Health aspects -- Methods, Brain stimulation -- Health aspects -- Research -- Methods, Postoperative care -- Methods -- Health aspects -- Research, Health, Psychology and mental health, Care and treatment, Complications and side effects, Research, Methods, Health aspects
Abstract

Background: The subthalamic nucleus is the preferred target for deep brain stimulation in patients with advanced Parkinson's disease. The site of permanent stimulation is the subject of ongoing debate, as [...]

Published
2003

41. Abstracts of the 6th FECS Conference 1998 Lectures

Author

Rowland, F. Sherwood, Blake, Donald R., Larsen, B. R., Lindskog, Anne, Peterson, Peter J., Williams, W. Peter, Wallington, T. J., Pilling, M. J., Carslaw, N., Creasey, D. J., Heard, D. E., Jacobs, P., Lee, J., Lewis, A. C., McQuaid, J. B., Stockwell, William R., Frank, Hartmut, Sacco, P., Cocheo, V., Lynge, E., Andersen, A., Nilsson, R., Barlow, L., Pukkala, E., Nordlinder, R., Boffetta, P., Grandjean, P., Heikkil, P., Hürte, L. G., Jakobsson, R., Lundberg, I., Moen, B., Partanen, T., Riise, T., Borowiak, A., De Saeger, E., Schnitzler, K. G., Gravenhorst, G., Jacobi, H. W., Moelders, S., Lammel, G., Busch, G., Beese, F. O., Dentener, F. J., Feichter, J., Fraedrich, K., Roelofs, G. J., Friedrich, R., Reis, S., Voehringer, F., Simpson, D., Moussiopoulos, N., Sahm, P., Tourlou, P. M., Salmons, R., Papameletiou, D., Maqueda, J. M., Suhr, Per B., Bell, W., Paton-Walsh, C., Woods, P. T., Partridge, R. H., Slemr, J., Slemr, F., Schmidbauer, N., Ravishankara, A. R., Jenkin, Michael E., de Leeuw, G., van Eijk, A. M. J., Flossmann, A. I., Wobrock, W., Mestayer, P. G., Tranchant, B., Ljungström, E., Karlsson, R., Larsen, S. E., Roemer, M., Builtjes, P. J. H., Koffi, Brigitte, Koffi, Ernest N’Dri, De Saeger, Emile, Ro-Poulsen, H., Mikkelsen, T. N., Hummelshøj, P., Hovmand, M. F., Simoneit, Bernd R. T., van der Meulen, A., Meyer, Michael B., Berndt, T., Böge, O., Stratmann, F., Cass, Glen R., Harrison, Roy M., Shi, Ji Ping, Hoffmann, T., Warscheid, B., Bandur, R., Marggraf, U., Nigge, W., Kamens, Richard, Jang, Myoseon, Strommen, Mike, Chien, Chao-Jung, Leach, Keri, Ammann, M., Kalberer, M., Arens, F., Lavanchy, V., Gâggeler, H. W., Baltensperger, U., Davies, J. A., Cox, R. A., Alonso, S. García, Pastor, R. Pérez, Argüello, Gustavo A., Willner, Helge, Berndt, T., Böge, O., Bogillo, V. I., Pokrovskiy, V. A., Kuraev, O. V., Gozhyk, P. F., Bolzacchini, E., Bruschi, M., Fantucci, P., Meinardi, S., Orlandi, M., Rindone, B., Bolzacchini, Ezio, Bohn, Birger, Rindone, Bruno, Bruschi, Maurizo, Zetzsch, Cornelius, Brussol, C., Duane, M., Larsen, B., Carlier, P., Kotzias, D., Caracena, A. Baeza, Aznar, A. Miñana, Ferradás, E. González, Christensen, C. S., Skov, H., Hummelshøj, P., Jensen, N. O., Lohse, C., Cocheo, V., Sacco, P., Chatzis, C., Cocheo, V., Sacco, P., Boaretto, C., Quaglio, F., Zaratin, L., Pagani, D., Cocheo, L., Cocheo, Vincenzo, Asnar, Agustin Minana, Baldan, Annerita, Ballesta, Pascual P., Boaretto, Caterina, Caracena, Antonia B., Ferradas, Enrique Gonzalez, Gonzalez-Flesca, Nobert, Goelen, Eddie, Hansen, Asger B., Sacco, Paolo, De Saeger, Emile, Skov, Henrik, Consonni, V., Gramatica, P., Santagostino, A., Galvani, P., Bolzacchini, E., Consonni, Viviana, Gramatica, Paola, Todeschini, Roberto, Dippel, G., Reinhardt, H., Zellner, R., Dämmer, K., Bednarek, G., Breil, M., Zellner, R., Febo, A., Allegrini, I., Giliberti, C., Perrino, C., Fogg, P. G. T., Geiger, H., Barnes, I., Becker, K. H., Maurer, T., Geyskens, F., Bormans, R., Lambrechts, M., Goelen, E., Giese, Martina, Frank, Hartmut, Glasius, M., Hornung, P., Jacobsen, J. K., Klausen, H. S., Klitgaard, K. C., Møller, C. K., Petersen, A. P. F., Petersen, L. S., Wessel, S., Hansen, T. S., Lohse, C., Boaretto, E., Heinemeier, J., Glasius, M., Di Bella, D., Lahaniati, M., Calogirou, A., Jensen, N. R., Hjorth, J., Kotzias, D., Larsen, B. R., Gonzalez-Flesca, N., Cicolella, A., Bates, M., Bastin, E., Gurbanov, M. A., Akhmedly, K. M., Balayev, V. S., Haselmann, K. F., Ketola, R., Laturnus, F., Lauritsen, F. R., Grøn, C., Herrmann, H., Ervens, B., Reese, A., Umschlag, Th., Wicktor, F., Zellner, R., Herrmann, H., Umschlag, Th., Müller, K., Bolzacchini, E., Meinardi, S., Rindone, B., Jenkin, Michael E., Hayman, Garry D., Jensen, N. O., Courtney, M., Hummelshøj, P., Christensen, C. S., Larsen, B. R., Johnson, Matthew S., Hegelund, Flemming, Nelander, Bengt, Kirchner, Frank, Klotz, B., Barnes, Ian, Sørensen, S., Becker, K. H., Etzkorn, T., Platt, U., Wirtz, K., Martín-Reviejo, M., Laturnus, Frank, Martinez, E., Cabañas, B., Aranda, A., Martín, P., Salgado, S., Rodriguez, D., Masclet, P., Jaffrezo, J. L., Hillamo, R., Mellouki, A., Le Calvé, S., Le Bras, G., Moriarty, J., O’Donnell, S., Wenger, J., Sidebottom, H., Mingarrol, M. T. Bomboi, Cosin, S., Pastor, R. Pérez, Alonso, S. García, Sanz, M. J., Bravo, I., Gonzalez, D., Pérez, M. A., Mustafaev, Islam, Mammadova, Saida, Noda, J., Hallquist, M., Langer, S., Ljungström, E., Nohara, K., Kutsuna, S., Ibusuki, T., Oehme, Michael, Kölliker, Stephan, Brombacher, Stephan, Merz, Leo, Pastor, R. Pérez, Alonso, S. García, Cabezas, A. Quejido, Peeters, J., Vereecken, L., El Yazal, J., Pfeffer, Hans-Ulrich, Breuer, Ludger, Platz, J., Nielsen, O. J., Sehested, J., Wallington, T. J., Ball, J. C., Hurley, M. D., Straccia, A. M., Schneider, W. F., Pérez-Casany, M. P., Nebot-Gil, I., Sánchez-Marín, J., Putz, E., Folberth, G., Pfister, G., Weissflog, L., Elansky, N. P., Sørensen, Søren, Barnes, Ian, Becker, K. H., Shao, M., Heiden, A. C., Kley, D., Rockel, P., Wildt, J., Silva, G. V. A., Vasconcelos, M. T., Fernandes, E. O., Santos, A. M. S., Skov, Henrik, Hansen, Asger, Løfstrøm, Per, Lorenzen, Gitte, Stabel, J. R., Wolkoff, P., Pedersen, T., Strom, A. B., Skov, Henrik, Hertel, Ole, Jensen, Finn Palmgren, Hjorth, Jens, Galle, Bosse, Wallin, Svante, Theloke, J., Libuda, H. G., Zabel, F., Touaty, Muriel, Bonsang, Bernard, Ullerstam, M., Langer, S., Ljungström, E., Wenger, John, Bonard, Amélie, Manning, Marcus, Nolan, Sinéad, O’Sullivan, Niamh, Sidebottom, Howard, Wenger, John, Collins, Eoin, Moriarty, Jennie, O’Donnell, Sinéad, Sidebottom, Howard, Wenger, John, Collins, Eoin, Moriarty, Jennie, O’Donnell, Sinéad, Sidebottom, Howard, Wenger, John, Sidebottom, Howard, Chadwick, Paul, O’Leary, Barbara, Treacy, Jack, Wolkoff, Peder, Clausen, Per A., Wilkins, Cornelius K., Hougaard, Karin S., Nielsen, Gunnar D., Zilinskis, Viktors, Jansons, Guntis, Peksens, Aigars, Lazdins, Agris, Arinci, Y. V., Erdöl, N., Ekinci, E., Okutan, H., Manlafalioglu, I., Bakeas, Evangelos B., Siskos, Panayotis A., Viras, Loizos G., Smirnioudi, Vasiliki N., Bottenheim, Jan W., Biesenthal, Thomas, Gong, Wanmin, Makar, Paul, Delmas, Véronique, Menard, Tamara, Tatry, Véronique, Moussafir, Jacques, Thomas, Dominique, Coppalle, Alexis, Ellermann, Thomas, Hertel, Ole, Skov, Henrik, Frohn, Lise, Manscher, Ole H., Friis, Jørgen, Girgzdiene, Rasa, Girgzdys, Aloyzas, Gurevich, N. A., Gårdfeldt, Katarina, Langer, Sarka, Hermans, C., Vandaele, A. C., Carleer, M., Fally, S., Colin, R., Bernath, P. F., Jenouvrier, A., Coquart, B., Mérienne, M. -F., Hertel, Ole, Frohn, Lise, Skov, Henrik, Ellermann, Thomas, Huntrieser, H., Schlager, H., Feigl, C., Kemp, Kåre, Palmgren, Finn, Kiilsholm, Sissi, Rasmussen, Alix, Sørensen, Jens Havskov, Klemm, Otto, Lange, Holger, Larsen, René Wugt, Larsen, Niels Wessel, Nicolaisen, Flemming, Sørensen, Georg Ole, Beukes, Jon Are, Larsen, Poul Bo, Jensen, Steen Solvang, Fenger, Jes, de Leeuw, Gerrit, Kunz, Gerard, Cohen, Leo, Schlünzen, Heinke, Muller, Frank, Schulz, Michael, Tamm, Susanne, Geernaert, Gary, Hertel, Ole, Pedersen, Britta, Geernaert, Lise Lotte Sørensen, Lund, Søren, Vignati, Elisabetta, Jickells, Tim, Spokes, Lucinda, Matei, C., Jinga, O. A., Jinga, D. C., Moliner, R., Braekman-Danheux, C., Fontana, A., Suelves, I., Thieman, T., Vassilev, S., Skov, Henrik, Hertel, Ole, Zlatev, Zahari, Brandt, Jørgen, Bastrup-Birk, Annemarie, Ellermann, Thomas, Frohn, Lise, Vandaele, A. C., Hermans, C., Carleer, M., Tsouli, A., Colin, R., Windsperger, Andreas M., Turi, Kristina, Dworak, Oliver, Zellweger, C., Weingartner, E., Rüttimann, R., Hofer, P., Baltensperger, U., Ziv, A., Iakovleva, E., Palmgren, F., Berkovicz, R., Skov, H., Alastuey, A., Querol, X., Chaves, A., Lopez-Soler, A., Ruiz, C., Andrees, J. M., Allegrini, I., Febo, A., Giusto, M., Angeloni, M., Di Filippo, P., D’Innocenzio, F., Lepore, L., Marconi, A., Arshinov, M. Yu., Belan, B. D., Davydov, D. K., Kovaleskii, V. K., Plotinov, A. P., Pokrovskii, E. V., Sklyadneva, T. K., Tolmachev, G. N., Arshinov, M. Yu., Belan, B. D., Sklyadneva, T. K., Behnke, Wolfgang, Elend, Manfred, Krüger, Ulrich, Zetzsch, Cornelius, Belan, B. D., Arshinov, M. Yu., Davydov, D. K., Kovalevskii, V. K., Plotnikov, A. P., Pokrovskii, E. V., Rasskazchikova, T. M., Sklyadneva, T. K., Tolmachev, G. N., Belan, B. D., Arshinov, M. Yu., Simonenkov, D. V., Tolmachev, G. N., Bilde, Merete, Aker, Pamela M., Börensen, C., Kirchner, U., Scheer, V., Vogt, R., Ellermann, T., Geernaert, L. L. S., Pryor, S. C., Barthelmie, R. J., Feilberg, Anders, Nielsen, Torben, Kamens, Richard M., Freitas, M. C., Marques, A. P., Reis, M. A., Alves, L. C., Ilyinskikh, N. N., Ilyinskikh, I. N., Ilyinskikh, E. N., Johansen, Keld, Stavnsbjerg, Peter, Gabrielsson, Pär, Bak, Flemming, Andersen, Erik, Autrup, Herman, Kamens, Richard, Jang, Myoseon, Strommen, Michael, Leach, Keri, Kirchner, U., Scheer, V., Börensen, C., Vogt, R., Igor, Komov, Svjatoslav, Galiy, Anatoliy, Burlak, Komov, I. L., Istchenko, A. A., Lourenço, M. G., MacTavish, D., Sirois, A., Masclet, Pierre, Jaffrezo, Jean Luc, van der Meulen, A., Milukaite, A., Morkunas, V., Jurgutis, P., Mikelinskiene, A., Nielsen, Torben, Feilberg, Anders, Binderup, Mona Lise, Pineda, M., Palacios, J. M., Garcia, E., Cilleruelo, C., Moliner, R., Popovitcheva, O. B., Trukhin, M. E., Persiantseva, N. M., Buriko, Yu, Starik, A. M., Demirdjian, B., Suzanne, J., Probst, T. U., Rietz, B., Alfassi, Z. B., Pokrovskiy, V. A., Zenobi, R., Bogatyr’ov, V. M., Gun’ko, V. M., Querol, X., Alastuey, A., Lopez-Soler, A., Mantilla, E., Plana, F., Artiño, B., Rauterberg-Wulff, A., Israël, G. W., Rocha, Teresa A. P., Duarte, Armando C., Röhrl, Andreas, Lammel, Gerhard, Spindler, G., Müller, K., Herrmann, H., Strommen, Michael R., Vignati, Elisabetta, de Leeuw, Gerrit, and Berkowicz, Ruwim

Published
1998
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44. Variability of Springtime Transpacific Pollution Transport During 2000-2006: The INTEX-5 Mission in the Context of Previous Years

Author

Pfister, G. G, Emmons, L. K, Edwards, D. P, Arellano, A, Sachse, G, and Campos, T

Subjects
Meteorology And Climatology
Abstract

We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part 8) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and .dynamics from changes in source strength. interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 113 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 213 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.

Published
2010

48. Measurements of Pollution in the Troposphere (MOPITT) Validation Exercises During Summer 2004 Field Campaigns over North America

Author

Emmons, L. K, Pfister, G. G, Edwards, D. P, Gille, J. C, Sachse, G, Blake, D, Wofsy, S, Gerbig, C, Matross, D, and Nedelec, P

Subjects
Geophysics
Abstract

Measurements of carbon monoxide (CO) made as part of three aircraft experiments during the summer of 2004 over North America have been used for the continued validation of the CO retrievals from the Measurements of Pollution in the Troposphere (MOPITT) instrument on board the Terra satellite. Vertical profiles measured during the NASA INTEX-A campaign, designed to be coincident with MOPITT overpasses, as well as measurements made during the COBRA-2004 and MOZAIC experiments, provided valuable validation comparisons. On average, the MOPITT CO retrievals are biased slightly high for these North America locations. While the mean bias differs between the different aircraft experiments (e.g., 7.0 ppbv for MOZAIC to 18.4 ppbv for COBRA at 700 hPa), the standard deviations are quite large, so the results for the three data sets can be considered consistent. On average, it is estimated that MOPITT is 7- 14% high at 700 hPa and 03% high at 350 hPa. These results are consistent with the validation results for the Carr, Colorado, Harvard Forest, Massachusetts, and Poker Flats, Alaska, aircraft profiles for "phase 2" presented by Emmons et al. (2004) and are generally within the design criteria of 10% accuracy.

Published
2007
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49. Evaluating Model Performance of an Ensemble-based Chemical Data Assimilation System During INTEX-B Field Mission

Author

Arellano, A. F., Jr, Raeder, K, Anderson, J. L, Hess, P. G, Emmons, L. K, Edwards, D. P, Pfister, G. G, Campos, T. L, and Sachse, G. W

Subjects
Meteorology And Climatology
Abstract

We present a global chemical data assimilation system using a global atmosphere model, the Community Atmosphere Model (CAM3) with simplified chemistry and the Data Assimilation Research Testbed (DART) assimilation package. DART is a community software facility for assimilation studies using the ensemble Kalman filter approach. Here, we apply the assimilation system to constrain global tropospheric carbon monoxide (CO) by assimilating meteorological observations of temperature and horizontal wind velocity and satellite CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument. We verify the system performance using independent CO observations taken on board the NSFINCAR C-130 and NASA DC-8 aircrafts during the April 2006 part of the Intercontinental Chemical Transport Experiment (INTEX-B). Our evaluations show that MOPITT data assimilation provides significant improvements in terms of capturing the observed CO variability relative to no MOPITT assimilation (i.e. the correlation improves from 0.62 to 0.71, significant at 99% confidence). The assimilation provides evidence of median CO loading of about 150 ppbv at 700 hPa over the NE Pacific during April 2006. This is marginally higher than the modeled CO with no MOPITT assimilation (-140 ppbv). Our ensemble-based estimates of model uncertainty also show model overprediction over the source region (i.e. China) and underprediction over the NE Pacific, suggesting model errors that cannot be readily explained by emissions alone. These results have important implications for improving regional chemical forecasts and for inverse modeling of CO sources and further demonstrate the utility of the assimilation system in comparing non-coincident measurements, e.g. comparing satellite retrievals of CO with in-situ aircraft measurements. The work described above also brought to light several short-comings of the data assimilation approach for CO profiles. Because of the limited vertical resolution of the measurement, the retrievals at different altitudes are correlated which can lead to problems with numerical error and overall efficiency. This has resulted in a manuscript that is about to be submitted to JGR

Published
2007

50. Evaluation of the MOCAGE Chemistry Transport Model during the ICARTT/ITOP Experiment

Author

Bousserez, N, Attie, J. L, Peuch, V. H, Michou, M, Pfister, G, Edwards, D, Emmons, L, Arnold, S, Heckel, A, Richter, A, Shlager, H, Lewis A, Avery, M, Sachse, G, Browell, E, and Ferrare, R

Subjects
Environment Pollution
Abstract

We evaluate the Meteo-France global chemistry transport 3D model MOCAGE (MOdele de Chimie Atmospherique a Grande Echelle) using the important set of aircraft measurements collected during the ICARRT/ITOP experiment. This experiment took place between US and Europe during summer 2004 (July 15-August 15). Four aircraft were involved in this experiment providing a wealth of chemical data in a large area including the North East of US and western Europe. The model outputs are compared to the following species of which concentration is measured by the aircraft: OH, H2O2, CO, NO, NO2, PAN, HNO3, isoprene, ethane, HCHO and O3. Moreover, to complete this evaluation at larger scale, we used also satellite data such as SCIAMACHY NO2 and MOPITT CO. Interestingly, the comprehensive dataset allowed us to evaluate separately the model representation of emissions, transport and chemical processes. Using a daily emission source of biomass burning, we obtain a very good agreement for CO while the evaluation of NO2 points out incertainties resulting from inaccurate ratio of emission factors of NOx/CO. Moreover, the chemical behavior of O3 is satisfactory as discussed in the paper.

Published
2007

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