Atmospheric Science

Simple measures of polar ozone depletion

by Carsten Lemmen

ClNO2 over Europe_in press GRL

by Gavin Phillips

Turbulent Structure functions in Geophysical Flows

by Jose M. Redondo

TURBULENT STRUCTURE FUNCTIONS IN GEOPHYSICAL FLOWS
O. Ben Mahjoub*, J. M. Redondo and R. Alami
Dept. Fisica Aplicada, (*Estadistica) Universitat Politècnica de Catalunya. Campus Nord B5, 08034 Barcelona, Spain

In geophysical flows, there are many instances, where turbulence is originated locally. such as in surface wave... more In geophysical flows, there are many instances, where turbulence is originated locally. such as in surface wave breaking at the surfzone or
by internai wave breaking in the lee of a mountain. The use of velocity structure functions and their moments may give an indication of
the spatial and time delay from the source of turbulence. The variation of the structure functions and the scaling exponents in decaying
non-homogeneous turbulence flows produced by a grid is investigated by means of sonic velocimeter SONTEK3-D. In the analysis we
invoke the concept of the Extended Self Similarity (ESS) and find that there are changes in the structure functions related to the
intermittency.
Keywords:JTurbulence

Turbulence structure of the atmospheric boundary layer in stable conditions

by Jose M. Redondo

TURBULENCE STRUCTURE OF THE ATMOSPHERIC
BOUNDARY LAYER IN STABLE CONDITIONS
J. M. Redondo (1), I. R. Cantalapiedra (1), O.B. Mahjoub (1),
Vindel (2) and C. Yagüe (2).
(1) Univ. Politecnica de Cataluña, Barcelona, Spain.
(2) Univ. Complutense de Madrid, Spain.


Conference proceedings

A partir de las mediciones de velocidad del aire, temperatura y humedad realizadas en la atmósfera en horario nocturno, se ha analizado la influencia de la estabilidad atmosférica en los flujos de momento y temperatura.
978-84-9747-185-5
http://hdl.handle.net/2117/1418

Data from SABLES98 experimental campaign have been used in order to study the
influence of stability (from weak... more Data from SABLES98 experimental campaign have been used in order to study the
influence of stability (from weak to strong stratification) on the flux-profile
relationships for momentum and heat: fm and fh. Standard instrumentation, 14
thermocouples and 3 sonic anemometers at three levels (5.8, 13.5 and 32 m) were
available from 10 to 28 September 1998 and calculations are done in order to extract
structure functions and intermittency. The results show increasing values of fm and fh
with increasing stability parameter and then values remain constant. As a consequence
of these constant, but different values of fm and fh for strong stability, when linear
similarity functions (Businger et al., 1971) are used to calculate surface fluxes of
momentum and heat an important underestimation of the turbulent mixing is produced.
The differences in structure and higher order moments between stable and neutral
turbulence is studied in terms of turbulent intermittent mixing and velocity PDF’s

Critique of the tracer-tracer correlation technique and its potential to analyze polar ozone loss in chemistry-climate models

by Carsten Lemmen

Co-authored with Rolf Müller, Paul Konopka, and Martin Dameris

The tracer-tracer correlation technique (TRAC) has been widely employed to infer chemical ozone loss from... more The tracer-tracer correlation technique (TRAC) has been widely employed to infer chemical ozone loss from observations. Yet, its applicability to chemistry-climate model(CCM) data is disputed. Here, we report the successful application of TRAC on theresults of a CCM simulation. By comparing TRAC-calculated ozone loss to ozone lossderived with the passive ozone method in a chemistry transport model we differentiateeffects of internal mixing and cross vortex boundary mixing on a TRAC referencecorrelation. As a test case, we consider results of a cold Arctic winter/spring episode froman E39/C experiment, where typical features, for example, sufficient polar stratosphericcloud formation potential, denitrification and dehydration, and intermittent and finalstratospheric warming events, are simulated. We find that internal mixing does not impact the TRAC-derived reference correlation at all. Mixing across the vortex boundary wouldlead to an underestimation of ozone loss by 10% when calculated with TRAC. We provide arguments that TRAC is a consistent and conservative method to derive chemicalozone loss and can be used to extract its chemical signature also from CCM simulations. As a consequence, we will be able to provide a lower bound for chemical ozone loss for model simulations where a passive ozone tracer is not available

Size distribution of alkyl amines in continental particulate matter and their online detection in the gas and particle phase

by Trevor Vandenboer

Atmospheric Chemistry and Physics, 11, 4319 - 4332, 2011

An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA),... more An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA) and triethylamine (TEA), in the ambient atmosphere. Limits of detection (3) are in the tens of pmol range for all of these amines, and good resolution is achieved for all compounds except for TMA and DEA. The technique was applied to the analysis of time-integrated samples collected using a micro-orifice uniform deposition impactor (MOUDI) with ten stages for size resolution of particles with aerodynamic diameters between 56 nm and 18 m. In eight samples from urban and rural continental airmasses, the mass loading of amines consistently maximized on the stage corresponding to particles with aerodynamic diameters between 320 and 560 nm. The molar ratio of amines to ammonium (R3NH+/NH4+) in fine aerosol ranged between 0.005 and 0.2, and maximized for the smallest particle sizes. The size-dependence of the R3NH+/NH4+ ratio indicates differences in the relative importance of the processes leading to the incorporation of amines and ammonia into secondary particles. The technique was also used to make simultaneous hourly online measurements of amines in the gas phase and in fine particulate matter using an Ambient Ion Monitor Ion Chromatograph (AIM-IC). During a ten day campaign in downtown Toronto, DMA, TMA + DEA, and TEA were observed to range from below detection limit to 2.7 ppt in the gas phase. In the particle phase, MAH+ and TMAH+ + DEAH+ were observed to range from below detection limit up to 15 ng m-3. The presence of detectable levels of amines in the particle phase corresponded to periods with higher relative humidity and higher mass loadings of nitrate. While the hourly measurements made using the AIM-IC provide data that can be used the evaluate the application of gas-particle partitioning models to amines, the strong size-dependence of the R3NH+/NH4+ ratio indicates that using bulk measurements may not be appropriate.

Characterization and optimization of an online system for the simultaneous measurement of atmospheric water-soluble constituents in the gas and particle phases

by Trevor Vandenboer

Milos Z. Markovic, Trevor C. VandenBoer and Jennifer G. Murphy

DOI: 10.1039/c2em00004k

In this work we present the results of extensive characterization and optimization of the Ambient Ion Monitor-Ion... more In this work we present the results of extensive characterization and optimization of the Ambient Ion Monitor-Ion Chromatograph (AIM-IC) system, an instrument developed by URG Corp. and Dionex Inc. for simultaneous hourly measurements of the water-soluble chemical composition of atmospheric fine particulate matter (PM2.5) and associated precursor gases. The sampling assembly of the AIM-IC consists of an inertial particle size-selection assembly, a parallel-plate wet denuder (PPWD) for the
collection of soluble gases, and a particle supersaturation chamber (PSSC) for collection of particles, in series. The analytical assembly of the AIM-IC consists of anion and cation IC units. The system detection limits were determined to be 41 ppt, 5 ppt, and 65 ppt for gas phase NH3(g), SO2(g), andHNO3(g) and 29 ng m^
3, 3 ng m^3, and 45 ng m
^3 for particle phase NH4+, SO42-, and NO3- respectively. From external trace gas calibrations with permeation sources, we determined that the
AIM-IC is biased low for NH3(g) (11%), SO2(g) (19%), and HNO3(g) (12%). The collection efficiency of SO2(g) was found to strongly depend on the composition of the denuder solution and was found to be the most quantitative with 5 mM H2O2 solution for mixing ratios as high as 107 ppb. Using a cellulose
membrane in the PPWD, the system responded to changes in SO2(g) and HNO3(g) within an hour, however for NH3(g), the timescale can be closer to 20 h. With a nylon membrane, the instrument response time for NH3(g) was significantly improved, becoming comparable to the responses for SO2(g) and HNO3(g). Performance of the AIM-IC for collection and analysis of PM2.5 was evaluated by generating known number concentrations of ammonium sulfate and ammonium nitrate particles (with an aerodynamic diameter of 300 nm) under laboratory conditions and by comparing AIM-IC measurements to measurements from a collocated Aerosol Mass Spectrometer (AMS) during a fieldsampling campaign. On average, the AIM-IC and AMS measurements agreed well and captured rapid ambient concentration changes at the same time. In this work we also present a novel inlet configuration and plumbing for the AIM-IC which minimizes sampling inlet losses, reduces peak
smearing due to sample carryover, and allows for tower-height sampling from the base of a research tower.

Isocyanic acid in a global chemistry transport model: Tropospheric distribution, budget, and identification of regions with potential health impacts

by Trevor Vandenboer

Paul. J. Young, Louisa. K. Emmons, James M. Roberts, Jean–François Lamarque, Christine Wiedinmyer, Patrick Veres, and Trevor C. VandenBoer

Journal of Geophysical Research - Atmospheres
doi:10.1029/2011JD017393, in press.

http://www.dailycamera.com/ci_20534406

http://news.discovery.com/earth/billions-inhale-acid-from-fires-120501.html

This study uses a global chemical transport model to estimate the distribution of isocyanic acid (HNCO). HNCO is... more This study uses a global chemical transport model to estimate the distribution of isocyanic acid (HNCO). HNCO is toxic, and concentrations exceeding 1 ppbv have been suggested to have negative health effects. Based on fire studies, HNCO emissions were scaled to those of hydrogen cyanide (30%), resulting in yearly total emissions of 1.5 Tg for 2008, from both anthropogenic and biomass burning sources. Loss processes included heterogeneous uptake (pH dependent), dry deposition (like formic acid), and reaction with the OH radical (k = 1 x 10^-15 molecule^-1 cm^3 s^-1). Annual mean surface HNCO concentrations were highest over parts of China (maximum of 470 pptv), but episodic fire emissions gave much higher levels, exceeding 4 ppbv in tropical Africa and the Amazon, and exceeding 10 ppbv in Southeast Asia and Siberia. This suggests that large biomass burning events could result in deleterious health effects for populations in these regions. For the tropospheric budget, using the model-calculated pH the HNCO lifetime was 37 days, with the split between dry deposition and heterogeneous loss being 95%:5%. Fixing the heterogeneous loss rate at pH = 7 meant that this process dominated, accounting for ~70% of the total loss, giving a lifetime of 6 days, and resulting in upper tropospheric concentrations that were essentially zero. However, changing the pH does not notably
impact the high concentrations found in biomass burning regions. More observational data is needed to evaluate the model, as well as a better representation of the likely underestimated biofuel emissions, which could mean more populations exposed to
elevated HNCO concentrations.

Quantifying atmospheric transport, chemistry, and mixing using a new trajectory-box model and a global atmospheric-chemistry GCM

by Hella Riede

Interview with Bjorn Stevens

by Hans von Storch

No 13. in a series of interviews with eminent atmospheric scientists, published in the AGU Atmospheric Science Section Newsletter. To see all interviews, plus others in otehr series, refer to http://coast.hzg.de/staff/storch/interview.htm#agu

Measurement of Atmospheric Fluxes of Radionuclides at a UK site using both Direct (Rain) and Indirect (Soils) Methods

by Dan Short

Direct measurements of radionuclide tracers are useful tools for
correcting proxy fluxes that are subject to post... more Direct measurements of radionuclide tracers are useful tools for
correcting proxy fluxes that are subject to post depositional changes. An analytical methodology was designed for the measurement of 210Pb and 7Be in rainwater. Atmospheric inputs of the radionuclides to Cumbria (UK) were recorded. Rainwater fluxes were then compared with measurements from soil cores. The annual deposition from April 1997 to March 1998 of 210Pb and 7Be was 165 ± 8 Bq m–2 and 3912 ± 120 Bq m–2, respectively, compared to an indirect 210Pb flux of 148 ± 7 Bq m–2 yr–1 calculated from soil core records.

Heavy metals and trace elements in atmospheric fall-out: Their relationship with topsoil and wheat element composition

by Gonzalo Bermudez

Journal of Hazardous Materials, In press (Available online 16 February 2012)

The objectives of this study were to determine the average concentrations and deposition rates of 28 elements in... more The objectives of this study were to determine the average concentrations and deposition rates of 28 elements in atmospheric bulk deposition and to elucidate associations among topsoil, bulk deposition and wheat element composition. The fluxes of arsenic (As), copper (Cu), lead (Pb) and zinc (Zn) deposition in Córdoba were higher than in other agro-ecosystems, which reflects both natural (geochemistry and topsoil removal) and anthropogenic sources. High lanthanide, uranium (U) and thorium (Th) concentrations revealed the impact of an open cast uranium mine. The highest enrichment factors (EF) were those of Cu, Pb, Zn and nickel (Ni), with calcium (Ca) being the most prominent in the surroundings of a cement plant. Industries and the transport of airborne urban pollutants were the main anthropogenic sources for Ca, Cu, Ni, Pb, Zn, cadmium (Cd), iron (Fe), manganese (Mn) and antimony (Sb). The concentrations of metals in wheat grain were predicted using the topsoil and atmospheric fall-out composition with R2 = 0.90, with the latter being the best explanatory variable. The present study highlights the potential health hazards of wheat consumption (Environmental Protection Agency) by the assessment of heavy metals in bulk atmospheric deposition.

2006 More examples of early 20th-century descriptions of teleconnection

by Marek Nowosad

Meteorologische Zeitschrift, Volume 15, Number 3, June 2006 , pp. 327-330(4)

English:
Some papers on the history of the study of teleconnections over the Atlantic Ocean and Europe have... more English:
Some papers on the history of the study of teleconnections over the Atlantic Ocean and Europe have already been published (e.g. Loewe 1937, 1966; van Loon and Rogers, 1978; Wanner et al., 2001; Stephenson et al., 2003). The article presents more examples of the knowledge of the correlations between atmospheric pressure distributions over the North Atlantic and the character of winters in Europe, described in two studies published in 1914/1915 in Polish. Klein's (1915) book contains a passage about winter temperatures being made milder by "western sea winds" brought over Europe and connected with the combined influence of the "Icelandic minimum" and the "Azores maximum". On the other hand, Merecki (1914) in his "Climatology of the Polish Lands" points out that the atmospheric pressure in Ponta Delgada and Stykkisholm is connected with the thermal conditions of the winter months in Warsaw. These are two more studies which demonstrate a relatively early recognition of the relationship between the distribution of air pressure over the Atlantic and the character of winters in Europe.

German:
Eine Reihe der die Forschungsgeschichte von Telekonnektionen über dem Nordatlantik und Europa betreffenden Aufsätze wurden veröffentlicht (Loewe 1937, 1966; van Loon and Rogers, 1978; Wanner et al., 2001; Stephenson et al., 2003). Im Artikel werden weitere Beispiele des Wissens über den Zusammenhang zwischen der Luftdruckverteilung über dem Nordatlantik mit dem Wintercharakter in Europa dargestellt, die in zwei in den Jahren 1914/1915 auf Polnisch veröffentlichten Aufsätzen beschrieben wurden. Das Buch von Klein (1915) beinhaltet einen Abschnitt über die ,,Milderung der Wintertemperatur durch,, westliche Seewinde, die über Europa geführt und mit dem Einfluss des isländischen Minimums und des Azoren-Maximums verbunden sind. Merecki (1914) stellt dagegen im Buch ,,Klimatologie von Polen dar, wie der Luftdruck in Ponta Delgada und Stykkisholm mit der Lufttemperatur von Wintermonaten in Warschau zusammenhängen. Das sind weitere Aufsätze, die relativ früh von den Abhängigkeiten zwischen der Luftdruckverteilung über dem Atlantik mit dem Wintercharakter in Europa berichten.

Verification of snowpack radiation transfer models using actinometry

by Gavin Phillips

Large estragole fluxes from oil palms in Borneo

by Gavin Phillips

Potential for photochemical ozone formation in the troposphere over the North Atlantic as derived from aircraft observations during ACSOE

by Gavin Phillips

Measurement of organic aerosol precursors over an oak forest

by Gavin Phillips

Micrometeorological measurements of anthropogenic VOC emissions from urban areas

by Gavin Phillips

ACCENT workshop abstract

2010 A comparison of the annual courses of the index of variability of circulation types: the example of the Hess-Brezowsky classification

by Marek Nowosad

Annales UMCS sec. B, Volume 65, Number 2 / 2010, Volume 65, 109-115, DOI 10.2478/v10066-010-0025-1

The values for April, May and November were positive for both 50-years periods.
The mean season index values are... more The values for April, May and November were positive for both 50-years periods.
The mean season index values are positive for Spring (0,35 and 0,37 σ for 1st and 2nd part of the 20th century) and negative for Winter (–0,13 and –0,25 σ). The mean values for Autumn were 0,32 σ (1901-1950) and –0,18 σ (1951-2000), as well as for Summer –0,51 σ and 0,02 σ. The index of variability of circulation types achieves larger values for Spring and Autumn than for Summer and Winter. This suggests, that the changeability of structure of the types of circulation is greater in Spring and Autumn than in Summer and Winter. This changeability decreased in Autumn, while it grew up in Summer during the 2nd half of the 20th century in comparison to the first half.

The convective storm initiation project

by Andrew Russell

Browning, K. A. and co-authors, including Russell, A. (2007)
Bulletin of the American Meteorological Society, 88, 1939-1955.

The convective storm initiation project: To study why, where, and when deep convection breaks out, an international... more The convective storm initiation project: To study why, where, and when deep convection breaks out, an international project obtained detailed observations of nascent convective clouds in maritime southern England and compared them with very high resolution forecast model results.