Trends in MODIS and AERONET derived aerosol optical thickness over Northern Europe.

2019 | Tellus B Chem Phys Meteorol | 71 (1) (1-21)

Long-term Aqua and Terra MODIS (MODerate resolution Imaging Spectroradiometer) Collections 5.1 and 6.1 (c051 and c061, respectively) aerosol data have been combined with AERONET (AERosol RObotic NETwork) ground-based sun photometer observations to examine trends in aerosol optical thickness (AOT, at 550 nm) over Northern Europe for the months April to September. For the 1927 and 1559 daily coincident measurements that were obtained for c051 and c061, respectively, MODIS AOT varied by 86 and 90%, respectively, within the predicted uncertainty of one standard deviation of the retrieval over land (ΔAOT = ±0.05 ± 0.15·AOT). For the coastal AERONET site Gustav Dalen Tower (GDT), Sweden, larger deviations were found for MODIS c051 and c061 (79% and 75%, respectively, within predicted uncertainty). The Baltic Sea provides substantially better statistical representation of AOT than the surrounding land areas and therefore favours the investigations of trends in AOT over the region. Negative trends of 1.5% and 1.2% per year in AOT, based on daily averaging, were found for the southwestern Baltic Sea from MODIS c051 and c061, respectively. This is in line with a decrease of 1.2% per year in AOT at the AERONET station Hamburg. For the western Gotland Basin area, Sweden, negative trends of 1.5%, 1.1% and 1.6% per year in AOT have been found for MODIS c051, MODIS c061 and AERONET GDT, respectively. The strongest trend of –1.8% per year in AOT was found for AERONET Belsk, Poland, which can be compared to –1.5% per day obtained from MODIS c051 over central Poland. The trends in MODIS and AERONET AOT are nearly all statistically significant at the 95% confidence level. The strongest aerosol sources are suggested to be located southwest, south and southeast of the investigation area, although the highest prevalence of pollution events is associated with air mass transport from southwest.

Beware the impact factor

2016 | Ambio | 45 (513-515)

Aviation effects on already-existing cirrus clouds

M. Tesche; P. Achtert; P. Glantz; K. J. Noone
2016 | Nat. Commun. | 7 (12016)

Determining the effects of the formation of contrails within natural cirrus clouds has proven to be challenging. Quantifying any such effects is necessary if we are to properly account for the influence of aviation on climate. Here we quantify the effect of aircraft on the optical thickness of already-existing cirrus clouds by matching actual aircraft flight tracks to satellite lidar measurements. We show that there is a systematic, statistically significant increase in normalized cirrus cloud optical thickness inside mid-latitude flight tracks compared with adjacent areas immediately outside the tracks.

Meteorological and aerosol effects on marine cloud microphysical properties

Sanchez, KJ; Russell, LM; Modini, RL; Frossard, AA; Ahlm, L; Corrigan, CE; Roberts, GC; Hawkins, LN; Schroder, JC; Bertram, AK; Zhao, R; Lee, AKY; Lin, JJ; Nenes, A; Wang, Z; Wonaschutz, A; Sorooshian, A; Noone, KJ; Jonsson, H; Toom, D; Macdonald, AM; Leaitch, WR; Seinfeld, JH
2016 | J. Geophys. Res.-Atmos. | 121 (8) (4142-4161)
2011 e-peace , chemical composition , condensation nucleus activity , counterflow virtual impactor , droplet formation , global climate models , hygroscopic growth , mixed-phase clouds , organic aerosol , stratocumulus clouds
Meteorology and microphysics affect cloud formation, cloud droplet distributions, and shortwave reflectance. The Eastern Pacific Emitted Aerosol Cloud Experiment and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets studies provided measurements in six case studies of cloud thermodynamic properties, initial particle number distribution and composition, and cloud drop distribution. In this study, we use simulations from a chemical and microphysical aerosol-cloud parcel (ACP) model with explicit kinetic drop activation to reproduce observed cloud droplet distributions of the case studies. Four cases had subadiabatic lapse rates, resulting in fewer activated droplets, lower liquid water content, and higher cloud base height than an adiabatic lapse rate. A weighted ensemble of simulations that reflect measured variation in updraft velocity and cloud base height was used to reproduce observed droplet distributions. Simulations show that organic hygroscopicity in internally mixed cases causes small effects on cloud reflectivity (CR) (<0.01), except for cargo ship and smoke plumes, which increased CR by 0.02 and 0.07, respectively, owing to their high organic mass fraction. Organic hygroscopicity had larger effects on droplet concentrations for cases with higher aerosol concentrations near the critical diameter (namely, polluted cases with a modal peak near 0.1 mu m). Differences in simulated droplet spectral widths (k) caused larger differences in CR than organic hygroscopicity in cases with organic mass fractions of 60% or less for the cases shown. Finally, simulations from a numerical parameterization of cloud droplet activation suitable for general circulation models compared well with the ACP model, except under high organic mass fraction.

Primary marine aerosol-cloud interactions off the coast of California

Modini, R. L.; Frossard, A. A.; Ahlm, L.; Russell, L. M.; Corrigan, C. E.; Roberts, G. C.; Hawkins, L. N.; Schroder, J. C.; Bertram, A. K.; Zhao, R.; Lee, A. K. Y.; Abbatt, J. P. D.; Lin, J.; Nenes, A.; Wang, Z.; Wonaschutz, A.; Sorooshian, A.; Noone, K. J.; Jonsson, H.; Seinfeld, J. H.; Toom-Sauntry, D.; Macdonald, A. M.; Leaitch, W. R.
2015 | J. Geophys. Res.-Atmos. | 120

Primary and secondary organics in the tropical Amazonian rainforest aerosols: Chiral analysis of 2-methyltetraols

Gonzales N.J.D.; Borg-Karlsson, A.-K.; Artaxo, P.; Guenther, A.; Krejci, R.; Noziere, B.; Noone K.J.
2014 | Environ. Sci.: Processes Impacts | 16 (6) (1413-1421)

This work presents the application of a new method to facilitate the distinction between biologically produced (primary) and atmospherically produced (secondary) organic compounds in ambient aerosols based on their chirality. The compounds chosen for this analysis were the stereomers of 2-methyltetraols, (2R, 3S)- and (2S, 3R)-methylerythritol, (L- and D-form, respectively), and (2S, 3S)- and (2R, 3R)-methylthreitol (L- and D-form), shown previously to display some enantiomeric excesses in atmospheric aerosols, thus to have at least a partial biological origin. In this work PM10 aerosol fractions were collected in a remote tropical rainforest environment near Manaus, Brazil, between June 2008 and June 2009 and analysed. Both 2-methylerythritol and 2-methylthreitol displayed a net excess of one enantiomer (either the L- or the D-form) in 60 to 72% of these samples. These net enantiomeric excesses corresponded to compounds entirely biological but accounted for only about 5% of the total 2-methyltetrol mass in all the samples. Further analysis showed that, in addition, a large mass of the racemic fractions (equal mixtures of D- and L-forms) was also biological. Estimating the contribution of secondary reactions from the isomeric ratios measured in the samples (=ratios 2-methylthreitol over 2-methylerythritol), the mass fraction of secondary methyltetrols in these samples was estimated to a maximum of 31% and their primary fraction to a minimum of 69%. Such large primary fractions could have been expected in PM10 aerosols, largely influenced by biological emissions, and would now need to be investigated in finer aerosols. This work demonstrates the effectiveness of chiral and isomeric analyses as the first direct tool to assess the primary and secondary fractions of organic aerosols.

Climate-induced changes in sea salt aerosol number emissions: 1870 to 2100

Struthers, H., A.; Ekman, M. L.; Glantz, P.; Iversen, T.; Kirkevåg, A.; Seland, Ø.; Mårtensson, E. M.; Noone, K.; Nilsson, E. D.
2013 | J. Geophys. Res.-Atmos. | 118 (1-13)

Planetary Boundaries: Exploring the Safe Operating Space for Humanity

Rockstrom, J; Steffen, W; Noone, K; Persson, A; Chapin, FS; Lambin, E; Lenton, TM; Scheffer, M; Folke, C; Schellnhuber, HJ; Nykvist, B; de Wit, CA; Hughes, T; van der Leeuw, S; Rodhe, H; Sorlin, S; Snyder, PK; Costanza, R; Svedin, U; Falkenmark, M; Karlberg, L; Corell, RW; Fabry, VJ; Hansen, J; Walker, B; Liverman, D; Richardson, K; Crutzen, P; Foley, J
2009 | Ecol. Soc. | 14 (2)
anthropogenic co2 , atmospheric aerosol loading , atmospheric co2 , biogeochemical nitrogen cycle , biological diversity , chemical pollution , climate change , coral-reefs , earth , environmental-change , food-production , global freshwater use , land system change , ocean acidification , phosphorus cycle , planetary boundaries , regime shifts , social-ecological systems , stratospheric ozone , sustainability , water-resources

Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems. We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere <350 ppm and/or a maximum change of +1 W m(-2) in radiative forcing); ocean acidification (mean surface seawater saturation state with respect to aragonite >= 80% of pre-industrial levels); stratospheric ozone (<5% reduction in O-3 concentration from pre-industrial level of 290 Dobson Units); biogeochemical nitrogen (N) cycle (limit industrial and agricultural fixation of N-2 to 35 Tg N yr(-1)) and phosphorus (P) cycle (annual P inflow to oceans not to exceed 10 times the natural background weathering of P); global freshwater use (<4000 km(3) yr(-1) of consumptive use of runoff resources); land system change (<15% of the ice-free land surface under cropland); and the rate at which biological diversity is lost (annual rate of <10 extinctions per million species). The two additional planetary boundaries for which we have not yet been able to determine a boundary level are chemical pollution and atmospheric aerosol loading. We estimate that humanity has already transgressed three planetary boundaries: for climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. Planetary boundaries are interdependent, because transgressing one may both shift the position of other boundaries or cause them to be transgressed. The social impacts of transgressing boundaries will be a function of the social-ecological resilience of the affected societies. Our proposed boundaries are rough, first estimates only, surrounded by large uncertainties and knowledge gaps. Filling these gaps will require major advancements in Earth System and resilience science. The proposed concept of "planetary boundaries" lays the groundwork for shifting our approach to governance and management, away from the essentially sectoral analyses of limits to growth aimed at minimizing negative externalities, toward the estimation of the safe space for human development. Planetary boundaries define, as it were, the boundaries of the "planetary playing field" for humanity if we want to be sure of avoiding major human-induced environmental change on a global scale.

A safe operating space for humanity

Rockstrom, J; Steffen, W; Noone, K; Persson, A; Chapin, FS; Lambin, EF; Lenton, TM; Scheffer, M; Folke, C; Schellnhuber, HJ; Nykvist, B; de Wit, CA; Hughes, T; van der Leeuw, S; Rodhe, H; Sorlin, S; Snyder, PK; Costanza, R; Svedin, U; Falkenmark, M; Karlberg, L; Corell, RW; Fabry, VJ; Hansen, J; Walker, B; Liverman, D; Richardson, K; Crutzen, P; Foley, JA
2009 | Nature | 461 (7263) (472-475)
biodiversity , climate , consequences , ecosystems , human impact , perspective , phosphorus , resilience , shifts , social-ecological systems

Microphysical and chemical characteristics of cloud droplet residuals and interstitial particles in continental stratocumulus clouds

Targino, A.C.; Noone, K.J.; Drewnick, F.; Schneider, J.; Krejci, R.; Olivares, G.; Hings, S.; Borrmann, S.
2007 | Atmos. Res. | 86 (225-240)

Single particle analysis of ice crystal residuals observed in orographic wave clouds over Scandinavia during INTACC experiment

2006 | Atmos. Chem. Phys. | 6 (1977-1990)

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Geovetenskapens Hus,
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Arrheniuslaboratoriet, Svante Arrhenius väg 16, Stockholm (Unit for Analytical and Toxicological Chemistry)

Mailing address:
Department of Environmental Science and Analytical Chemistry (ACES)
Stockholm University
106 91 Stockholm

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