The vertical distribution of aerosol in the atmosphere affects its ability to act as cloud condensation nuclei and changes the amount of sunlight it absorbs or reflects. Common global measurements of aerosol provide no information about this vertical distribution. Using a global collection of in situ aircraft measurements to compare with an aerosol—climate model ECHAM-HAM , we explore the key processes controlling this distribution and find that wet removal plays a key role.
Colarco, Douglas A. Day, Karl D. Froyd, Bernd Heinold, Duseong S. Jo, Joseph M. Katich, Jack K. Kodros, Benjamin A. Nault, Jeffrey R. Schill, Jason C. Schroder, Joshua P. Schwarz, Dianna T.
Organic aerosols OA are a key source of uncertainty in aerosol climate effects. We show that global models predict well the OA distribution, but not the relative contribution of OA emissions vs. We find a pronounced maximum in aerosol extinction in the upper troposphere and lower stratosphere over the Tibetan Plateau during the Asian summer monsoon, caused mainly by mineral dust emitted from the northern Tibetan Plateau and slope area, lofted to and accumulating within the anticyclonic circulation.
Mineral dust, water-soluble compounds, such as nitrate and sulfate, and associated liquid water dominate aerosol extinction around the tropopause within the Asian summer monsoon anticyclone. Giulia Saponaro, Moa K.
Karset, Ari Laaksonen, and Ulrike Lohmann. The understanding of cloud processes is based on the quality of the representation of cloud properties. We compared cloud parameters from three models with satellite observations. We report on the performance of each data source, highlighting strengths and deficiencies, which should be considered when deriving the effect of aerosols on cloud properties. Bruns, Simone M. Slowik, and Imad El Haddad.
Novel parameterization methods based on a genetic algorithm approach allowed estimation of precursor class contributions to SOA and evaluation of the effect of emission variability on SOA yield predictions. Eva Y. Crowley, Dirk Dienhart, Philipp G. The Arabian Peninsula is a global hot spot of ozone pollution.
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Our measurements, made on a ship in summer , indicate underlying reasons. Despite being at sea, we observed ozone-forming reactive trace gases measured as so-called total OH reactivity comparable to highly populated urban regions in amount and composition.
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This is due to strong emissions from oil extraction and ship traffic. These emissions were quickly converted to ozone due to intense solar irradiation and high temperatures. Felipe D.
Thornton, Urs Baltensperger, Andre S. Prevot, and Jay G. We present a novel, field-deployable extractive electrospray time-of-flight mass spectrometer EESI-TOF , which provides real-time, near-molecular measurements of organic aerosol at atmospherically relevant concentrations, addressing a critical gap in existing measurement capabilities. Richard Leaitch, John K. Kodros, Megan D. Bertram, Andreas Herber, Jonathan P. Abbatt, and Jeffrey R. Black carbon is a factor in the warming of the Arctic atmosphere due to its ability to absorb light, but the uncertainty is high and few observations have been made in the high Arctic above 80 north.
We combine airborne and ground-based observations in the springtime Arctic, at and above 80 north, with simulations from a global model to show that light absorption by black carbon may be much larger than modelled. However, the uncertainty remains high. Ryan, and Lindsay Lee. Global models of tropospheric chemistry and transport show a persistent diversity in results that has not been fully explained.
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We demonstrate the first use of global sensitivity analysis consistently across three independent models to explore these differences, and reveal both clear similarities and surprising differences which have important implications for our assessment of future atmospheric composition change. We present an over year-long time series of aerosol optical properties AOPs measured at a rural boreal forest site. Knowledge of AOPs is needed in determining the direct effect of aerosol particles on climate. We observed decreasing trends in scattering and absorption and increasing trends in backscattering fraction and single-scattering albedo.
Trends of single-scattering albedo and backscattering fraction increased the efficiency of aerosol particles to scatter radiation back into space. Tuan V. Here, we applied a novel machine-learning-based model to determine the real trend in air quality from to in Beijing to assess the efficacy of the plan. We showed that the action plan led to a major reduction in primary emissions and significant improvement in air quality. The marked decrease in PM 2. Julie M. Nicely, Bryan N. Duncan, Thomas F.
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Hanisco, Glenn M. Wolfe, Ross J. Salawitch, Makoto Deushi, Amund S. Kinnison, Andrew Klekociuk, Michael E. Murray, Gunnar Myhre, Luke D. Westervelt, and Guang Zeng. The short-lived, very reactive species hydroxyl radical OH is responsible for oxidizing and removing many pollutants and greenhouse gases like CH 4 , the second-most important anthropogenic greenhouse gas. However, its reactive nature, spatial heterogeneity, and dependence on so many other chemical, radiative, and physical factors make OH difficult to model and measure.
We use a machine learning approach to quantify the key drivers of OH differences between models and OH variations over time. In addition to isoprene, monoterpenes, sesquiterpenes, and the low-volatility diterpenes, various terpene reaction products are characterized. Through the analysis of terpene chemistry, this work demonstrates the capability of Vocus PTR-TOF in the detection of oxidized reaction products, highlighting its importance in investigating atmospheric oxidation processes.
Laura Kiely, Dominick V. In , a large fire episode occurred in Indonesia, reducing air quality. Fires occurred predominantly on peatland, where large uncertainties are associated with emissions. Current fire emissions datasets underestimate peat fire emissions.
We created new fire emissions data, with data specific to Indonesian peat fires. Using these emissions in simulations of particulate matter and aerosol optical depth shows an improvement over simulations using current data, when compared with observations. Douglas S.
Hamilton, Rachel A. Rathod, Jessica S. Wan, Mingxuan Wu, and Natalie M. MIMI v1. Understanding the iron cycle is important due to its role as an essential micronutrient for ocean phytoplankton; its supply limits primary productivity in many of the world's oceans. Human activity has perturbed the iron cycle, and MIMI is capable of diagnosing many of these impacts; hence, it is important for future climate studies.
Pyruvic acid, CH 3 C O C O OH, is an organic acid of biogenic origin that plays a crucial role in plant metabolism, is present in tropospheric air in both gas-phase and aerosol-phase and is implicated in the formation of secondary organic aerosols. From the first gas-phase measurements of pyruvic acid in the Finnish boreal forest in September we derive its source strength and discuss potential sources and sinks, with a focus on the relevance of gas-phase pyruvic acid for radical chemistry.
Severe pollution of the Beijing atmosphere is a frequent occurrence. The airborne particles which characterize the episodes of haze contain a wide range of chemical constituents but organic compounds make up a substantial proportion.