ALBERT

Description: Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pierre Auger Collaboration -- Abraham, J -- Abreu, P -- Aglietta, M -- Aguirre, C -- Allard, D -- Allekotte, I -- Allen, J -- Allison, P -- Alvarez, C -- Alvarez-Muniz, J -- Ambrosio, M -- Anchordoqui, L -- Andringa, S -- Anzalone, A -- Aramo, C -- Argiro, S -- Arisaka, K -- Armengaud, E -- Arneodo, F -- Arqueros, F -- Asch, T -- Asorey, H -- Assis, P -- Atulugama, B S -- Aublin, J -- Ave, M -- Avila, G -- Backer, T -- Badagnani, D -- Barbosa, A F -- Barnhill, D -- Barroso, S L C -- Bauleo, P -- Beatty, J -- Beau, T -- Becker, B R -- Becker, K H -- Bellido, J A -- Benzvi, S -- Berat, C -- Bergmann, T -- Bernardini, P -- Bertou, X -- Biermann, P L -- Billoir, P -- Blanch-Bigas, O -- Blanco, F -- Blasi, P -- Bleve, C -- Blumer, H -- Bohacova, M -- Bonifazi, C -- Bonino, R -- Boratav, M -- Brack, J -- Brogueira, P -- Brown, W C -- Buchholz, P -- Bueno, A -- Busca, N G -- Caballero-Mora, K S -- Cai, B -- Camin, D V -- Caruso, R -- Carvalho, W -- Castellina, A -- Catalano, O -- Cataldi, G -- Cazon-Boado, L -- Cester, R -- Chauvin, J -- Chiavassa, A -- Chinellato, J A -- Chou, A -- Chye, J -- Clark, P D J -- Clay, R W -- Colombo, E -- Conceicao, R -- Connolly, B -- Contreras, F -- Coppens, J -- Cordier, A -- Cotti, U -- Coutu, S -- Covault, C E -- Creusot, A -- Cronin, J -- Dagoret-Campagne, S -- Daumiller, K -- Dawson, B R -- de Almeida, R M -- De Donato, C -- de Jong, S J -- De La Vega, G -- de Mello Junior, W J M -- de Mello Neto, J R T -- De Mitri, I -- de Souza, V -- Del Peral, L -- Deligny, O -- Selva, A Della -- Fratte, C Delle -- Dembinski, H -- Di Giulio, C -- Diaz, J C -- Dobrigkeit, C -- D'Olivo, J C -- Dornic, D -- Dorofeev, A -- Dos Anjos, J C -- Dova, M T -- D'Urso, D -- Duvernois, M A -- Engel, R -- Epele, L -- Erdmann, M -- Escobar, C O -- Etchegoyen, A -- Facal San Luis, P -- Falcke, H -- Farrar, G -- Fauth, A C -- Fazzini, N -- Fernandez, A -- Ferrer, F -- Ferry, S -- Fick, B -- Filevich, A -- Filipcic, A -- Fleck, I -- Fonte, R -- Fracchiolla, C E -- Fulgione, W -- Garcia, B -- Garcia Gamez, D -- Garcia-Pinto, D -- Garrido, X -- Geenen, H -- Gelmini, G -- Gemmeke, H -- Ghia, P L -- Giller, M -- Glass, H -- Gold, M S -- Golup, G -- Albarracin, F Gomez -- Berisso, M Gomez -- Herrero, R Gomez -- Goncalves, P -- Goncalves do Amaral, M -- Gonzalez, D -- Gonzalez, J G -- Gonzalez, M -- Gora, D -- Gorgi, A -- Gouffon, P -- Grassi, V -- Grillo, A -- Grunfeld, C -- Guardincerri, Y -- Guarino, F -- Guedes, G P -- Gutierrez, J -- Hague, J D -- Hamilton, J C -- Hansen, P -- Harari, D -- Harmsma, S -- Harton, J L -- Haungs, A -- Hauschildt, T -- Healy, M D -- Hebbeker, T -- Heck, D -- Hojvat, C -- Holmes, V C -- Homola, P -- Horandel, J -- Horneffer, A -- Horvat, M -- Hrabovsky, M -- Huege, T -- Iarlori, M -- Insolia, A -- Ionita, F -- Italiano, A -- Kaducak, M -- Kampert, K H -- Keilhauer, B -- Kemp, E -- Kieckhafer, R M -- Klages, H O -- Kleifges, M -- Kleinfeller, J -- Knapik, R -- Knapp, J -- Koang, D-H -- Kopmann, A -- Krieger, A -- Kromer, O -- Kumpel, D -- Kunka, N -- Kusenko, A -- La Rosa, G -- Lachaud, C -- Lago, B L -- Lebrun, D -- Lebrun, P -- Lee, J -- Leigui de Oliveira, M A -- Letessier-Selvon, A -- Leuthold, M -- Lhenry-Yvon, I -- Lopez, R -- Lopez Aguera, A -- Lozano Bahilo, J -- Maccarone, M C -- Macolino, C -- Maldera, S -- Malek, M -- Mancarella, G -- Mancenido, M E -- Mandat, D -- Mantsch, P -- Mariazzi, A G -- Maris, I C -- Martello, D -- Martinez, J -- Martinez Bravo, O -- Mathes, H J -- Matthews, J -- Matthews, J A J -- Matthiae, G -- Maurizio, D -- Mazur, P O -- McCauley, T -- McEwen, M -- McNeil, R R -- Medina, M C -- Medina-Tanco, G -- Meli, A -- Melo, D -- Menichetti, E -- Menschikov, A -- Meurer, Chr -- Meyhandan, R -- Micheletti, M I -- Miele, G -- Miller, W -- Mollerach, S -- Monasor, M -- Monnier Ragaigne, D -- Montanet, F -- Morales, B -- Morello, C -- Moreno, E -- Moreno, J C -- Morris, C -- Mostafa, M -- Muller, M A -- Mussa, R -- Navarra, G -- Navarro, J L -- Navas, S -- Nellen, L -- Newman-Holmes, C -- Newton, D -- Thi, T Nguyen -- Nierstenhofer, N -- Nitz, D -- Nosek, D -- Nozka, L -- Oehlschlager, J -- Ohnuki, T -- Olinto, A -- Olmos-Gilbaja, V M -- Ortiz, M -- Ostapchenko, S -- Otero, L -- Pakk Selmi-Dei, D -- Palatka, M -- Pallotta, J -- Parente, G -- Parizot, E -- Parlati, S -- Pastor, S -- Patel, M -- Paul, T -- Pavlidou, V -- Payet, K -- Pech, M -- Pekala, J -- Pelayo, R -- Pepe, I M -- Perrone, L -- Petrera, S -- Petrinca, P -- Petrov, Y -- Ngoc, Dieppham -- Ngoc, Dongpham -- Pham Thi, T N -- Pichel, A -- Piegaia, R -- Pierog, T -- Pimenta, M -- Pinto, T -- Pirronello, V -- Pisanti, O -- Platino, M -- Pochon, J -- Porter, T A -- Privitera, P -- Prouza, M -- Quel, E J -- Rautenberg, J -- Reucroft, S -- Revenu, B -- Rezende, F A S -- Ridky, J -- Riggi, S -- Risse, M -- Riviere, C -- Rizi, V -- Roberts, M -- Robledo, C -- Rodriguez, G -- Rodriguez Frias, D -- Rodriguez Martino, J -- Rodriguez Rojo, J -- Rodriguez-Cabo, I -- Ros, G -- Rosado, J -- Roth, M -- Rouille-d'Orfeuil, B -- Roulet, E -- Rovero, A C -- Salamida, F -- Salazar, H -- Salina, G -- Sanchez, F -- Santander, M -- Santo, C E -- Santos, E M -- Sarazin, F -- Sarkar, S -- Sato, R -- Scherini, V -- Schieler, H -- Schmidt, F -- Schmidt, T -- Scholten, O -- Schovanek, P -- Schussler, F -- Sciutto, S J -- Scuderi, M -- Segreto, A -- Semikoz, D -- Settimo, M -- Shellard, R C -- Sidelnik, I -- Siffert, B B -- Sigl, G -- De Grande, N Smetniansky -- Smialkowski, A -- Smida, R -- Smith, A G K -- Smith, B E -- Snow, G R -- Sokolsky, P -- Sommers, P -- Sorokin, J -- Spinka, H -- Squartini, R -- Strazzeri, E -- Stutz, A -- Suarez, F -- Suomijarvi, T -- Supanitsky, A D -- Sutherland, M S -- Swain, J -- Szadkowski, Z -- Takahashi, J -- Tamashiro, A -- Tamburro, A -- Tascau, O -- Tcaciuc, R -- Thomas, D -- Ticona, R -- Tiffenberg, J -- Timmermans, C -- Tkaczyk, W -- Todero Peixoto, C J -- Tome, B -- Tonachini, A -- Torresi, D -- Travnicek, P -- Tripathi, A -- Tristram, G -- Tscherniakhovski, D -- Tueros, M -- Tunnicliffe, V -- Ulrich, R -- Unger, M -- Urban, M -- Valdes Galicia, J F -- Valino, I -- Valore, L -- van den Berg, A M -- van Elewyck, V -- Vazquez, R A -- Veberic, D -- Veiga, A -- Velarde, A -- Venters, T -- Verzi, V -- Videla, M -- Villasenor, L -- Vorobiov, S -- Voyvodic, L -- Wahlberg, H -- Wainberg, O -- Waldenmaier, T -- Walker, P -- Warner, D -- Watson, A A -- Westerhoff, S -- Wieczorek, G -- Wiencke, L -- Wilczynska, B -- Wilczynski, H -- Wileman, C -- Winnick, M G -- Wu, H -- Wundheiler, B -- Xu, J -- Yamamoto, T -- Younk, P -- Zas, E -- Zavrtanik, D -- Zavrtanik, M -- Zech, A -- Zepeda, A -- Ziolkowski, M -- Kegl, B -- New York, N.Y. -- Science. 2007 Nov 9;318(5852):938-43.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17991855" target="_blank"〉PubMed〈/a〉

Description: Nocturnal chemistry in the atmospheric boundary layer plays a key role in determining the initial chemical conditions for photochemistry during the following morning as well as influencing the budgets of O3 and NO2. Despite its importance, chemistry in the nocturnal boundary layer (NBL), especially in heavily polluted urban areas, has received little attention so far, which greatly limits the current understanding of the processes involved. In particular, the influence of vertical mixing on chemical processes gives rise to complex vertical profiles of various reactive trace gases and makes nocturnal chemistry altitude-dependent. The processing of pollutants is thus driven by a complicated, and not well quantified, interplay between chemistry and vertical mixing. In order to gain a better understanding of the altitude-dependent nocturnal chemistry in the polluted urban environment, a field study was carried out in the downtown area of Phoenix, AZ, in summer 2001. Vertical profiles of reactive species, such as O3, NO2, and NO3, were observed in the lowest 140 m of the troposphere throughout the night. The disappearance of these trace gas vertical gradients during the morning coincided with the morning transition from a stable NBL to a well-mixed convective layer. The vertical gradients of trace gas levels were found to be dependent on both surface NOx emission strength and the vertical stability of the NBL. The vertical gradients of Ox, the sum of O3 and NO2, were found to be much smaller than those of O3 and NO2, revealing the dominant role of NO emissions followed by the O3+NO reaction for the altitude-dependence of nocturnal chemistry in urban areas. Dry deposition, direct emissions, and other chemical production pathways of NO2 also play a role for the Ox distribution. Strong positive vertical gradients of NO3, that are predominantly determined by NO3 loss near the ground, were observed. The vertical profiles of NO3 and the calculated vertical profiles of its reservoir species (N2O5) confirm earlier model results suggesting complex vertical distributions of atmospheric denoxification processes during the night.

Description: We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs) were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS) in air and water. Due to the inhomogeneous distribution of macroalgae at the German North Sea Coast we found a clear connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, especially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. We found CH2I2 at levels of up to 20 pptv, and a clear anti-correlation with the appearance of IO. The IO mixing ratio reached up to 7.7±0.5 ppt(pmol/mol) during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. For the two recent campaigns the DOAS spectra were evaluated for BrO, OIO and I2, but none of these species could be clearly identified (average detection limits around 2 ppt, 3 ppt, 20 ppt, resp., significantly higher in individual cases). Only in the Mace Head spectra evidence was found for the presence of OIO. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, we re-analyzed spectra in the 500–600 nm range taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. We identified molecular iodine above the detection limit (~20 ppt), with peak mixing ratios of 61±12 ppt. Since I2 was undetectable during the Brittany campaign, we suggest that iodine may not be released into the atmosphere by macroalgae in general, but only by a special type of the laminaria species under oxidative stress. Only during periods of extraordinarily low water (spring-tide), the plant is exposed to ambient air and may release gaseous iodine in some way to the atmosphere. The results of our re-analysis of spectra from the PARFORCE campaign in 1998 support this theory. Hence, we feel that we can provide an explanation for the different I2 levels in Brittany and Mace Head.

Description: We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was re-evaluated. During these field campaigns volatile halogenated organic compounds (VHOCs) were determined by GC/ECD-ICPMS in air and water. Due to the spatial distribution of macroalgae at the German North Sea Coast we found a clear connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, especially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. We found CH2I2 at levels of up to 20 pptv, and a clear anti-correlation with the appearance of IO. The IO mixing ratio reached up to 7.7±0.5 ppt(pmol/mol) during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. For the two campaigns the DOAS spectra were evaluated for BrO, OIO and I2, but none of these species could be clearly identified (detection limits around 2 ppt, 3 ppt, 20 ppt, resp.). Only in the Mace Head spectra evidence was found for the presence of OIO. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, we re-analyzed spectra in the 500–600 nm range taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. We identified molecular iodine above the detection limit (~20 ppt), with peak concentrations of 61±12 ppt. Since I2 was undetectable during the Brittany campaign, we suggest that iodine may not be released into the atmosphere by macroalgae in general, but only by a special type of the laminaria species under oxidative stress. Only during periods of extraordinarily low water (spring-tide), is the plant exposed to ambient air and may release gaseous iodine in some way to the atmosphere. The result of our re-analysis of spectra from the PARFORCE campaign in 1998 support this theory. Hence, we feel that we can provide an explanation for the different I2 levels in Brittany and Mace Head.

Description: Nocturnal chemistry in the atmospheric boundary layer plays a key role in determining the initial chemical conditions for photochemistry during the following morning as well as influencing the budgets of O3 and NO2. Despite its importance, chemistry in the nocturnal boundary layer (NBL), especially in heavily polluted urban areas, has received little attention so far, which greatly limits the current understanding of the processes involved. In particular, the influence of vertical mixing on chemical processes gives rise to complex vertical profiles of various reactive trace gases and makes nocturnal chemistry altitude-dependent. The processing of pollutants is thus driven by a complicated, and not well quantified, interplay between chemistry and vertical mixing. In order to gain a better understanding of the altitude-dependent nocturnal chemistry in the polluted urban environment, a field study was carried out in the downtown area of Phoenix, AZ, in summer 2001. Vertical profiles of reactive species, such as O3, NO2, and NO3, were observed in the lowest 140 m of the troposphere throughout the night. The disappearance of these trace gas vertical profiles during the morning coincided with the morning transition from a stable NBL to a well-mixed convective layer. The vertical gradients of trace gas levels were found to be dependent on both surface NOx emission strength and the vertical stability of the NBL. The vertical gradients of Ox, the sum of O3 and NO2, were found to be much smaller than those of O3 and NO2, revealing the dominant role of NO emissions followed by the O3+NO reaction for the altitude-dependence of nocturnal chemistry in urban areas. Dry deposition, direct emissions, and other chemical production pathways of NO2 also play a role for the Ox distribution. Strong positive vertical gradients of NO3, that are predominantly determined by NO3 loss near the ground, were observed. The vertical profiles of NO3 and its reservoir species (N2O5) confirm earlier model results suggesting complex vertical distributions of atmospheric denoxification processes during the night.