Chemically active climate compounds are either primary compounds like methane (CH4), removed by oxidation in the atmosphere, or secondary compounds like ozone (O3), sulfate and organic aerosols, both formed and removed in the atmosphere. Man-induced climate-chemistry interaction is a two-way process: Emissions of pollutants change the atmospheric composition contributing to climate change through the aforementioned climate components, and climate change, through changes in temperature, dynamics, the hydrological cycle, atmospheric stability, and biosphere-atmosphere interactions, affects the atmospheric composition and oxidation processes in the troposphere. Here we present progress in our understanding of processes of importance for climate-chemistry interactions, and their contributions to changes in atmospheric composition and climate forcing. A key factor is the oxidation potential involving compounds like O3 and the hydroxyl radical (OH). Reported studies represent both current and future ...
Upper troposphere cloud top heights (CTHs), restricted to cloud top pressures (CTPs) , 500 hPa, inferred using four satellite retrieval methods applied to Twelfth Geostationary Operational Environmental Satellite (GOES‐12) data are evaluated using measurements during the July-August 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The four methods are the single‐layer CO2‐absorption technique (SCO2AT), a modified CO2‐absorption technique (MCO2AT) developed for improving both single‐layered and multilayered cloud retrievals, a standard version of the Visible Infrared Solar‐infrared Split‐window Technique (old VISST), and a new version of VISST (new VISST) recently developed to improve cloud property retrievals. They are evaluated by comparing with ER‐2 aircraft‐based Cloud Physics Lidar (CPL) data taken during 9 days having extensive upper troposphere cirrus, anvil, and convective clouds. Compared to the 89% coverage by upper tropospheric clouds detected ...
First, we simply cannot mix the air in the troposphere and the stratosphere. The troposphere is the layer of the atmosphere at the earths surface. The troposphere contains 75% of all the air found in our atmosphere and 99% of the water vapor. The air in the troposphere is in constant motion, with both horizontal and vertical air currents. The combination of vigorous air movement and water vapor creates weather. The troposphere is capped by a thin layer known as the tropopause, which is a region of stable temperature that helps to confine most weather phenomena and "bad" ozone to the troposphere. The stratosphere is the second layer in the atmosphere from the earths surface. The lower part of the stratosphere contains the ozone layer. The ozone layer prevents harmful ultraviolet radiation from reaching the earths surface by absorbing the rays, causing the ozone layer and the air above it to warm. The warm air tends to remain in the upper stratosphere, and cool air remains lower. The layering ...
We report airborne measurements of acetaldehyde (CH3CHO) during the first and second deployments of the National Aeronautics and Space Administration Atmospheric Tomography Mission (ATom). The budget of CH3CHO is examined using the Community Atmospheric Model with chemistry (CAM‐chem), with a newly developed online air‐sea exchange module. The upper limit of the global ocean net emission of CH3CHO is estimated to be 34 Tg/a (42 Tg/a if considering bubble‐mediated transfer), and the ocean impacts on tropospheric CH3CHO are mostly confined to the marine boundary layer. Our analysis suggests that there is an unaccounted CH3CHO source in the remote troposphere and that organic aerosols can only provide a fraction of this missing source. We propose that peroxyacetic acid is an ideal indicator of the rapid CH3CHO production in the remote troposphere. The higher‐than‐expected CH3CHO measurements represent a missing sink of hydroxyl radicals (and halogen radical) in current chemistry‐climate ...
A new multi-wavelength lidar is introduced. The characteristics of 532 nm extinction coefficient profiles of cloud and aerosol in the upper troposphere in Beijing from January to April, 2000 are emphatically analyzed.Results show that the aerosol optical depth between 6 km and 11 km changes from 0.0152 to 0.0284 with a mean value of 0.0192?The cloud optical depth between 6 km and 11 km ranges from 0.014 to 0.23. The largest cloud thickness is about 6 km. On April 6, a very strong dust storm appeared over Beijing area. On April 7, there was no visible cloud; while as shown in lidar measurements, there was an aerosol layer spread from 4 km to 10 km. This aerosol layer, estimated as the sand-dust layer transported from remote desert areas, has the largest extinction coefficient at the height of about 8 km,which is about one order of magnitude larger than that in the clear (no cloud) day.
In situ measurements of water vapor and temperature from recent aircraft campaigns have provided evidence that the upper troposphere is frequently supersaturated with respect to ice. The peak relative humidities with respect to ice (RHI) occasionally approached water saturation at temperatures ranging from -40°C to -70°C in each of the campaigns. The occurrence frequency of ice supersaturation ranged from about 20% to 45%. Even on flight segments when no ice crystals were detected, ice supersaturation was measured about 5-20% of the time. A numerical cloud model is used to simulate the formation of optically thin, low ice number density cirrus clouds in these supersaturated regions. The potential for scavenging of ice nuclei (IN) by these clouds is evaluated. The simulations suggest that if less than about 5 x 10¯³ to 2 x 10¯² cm¯³ ice nuclei are present when these supersaturations are generated, then the cirrus formed should be subvisible. These low ice number density clouds scavenge ...
Theme: Basic processes. Start date: Cohort 1: 2019. Supervisors: Dr Bryan Bzdek (Bristol) and Dr Matthew Watson (Bristol). The surface tension of atmospheric aerosols impacts their ability to serve as cloud droplet seeds and affect climate. This project will develop approaches to measure droplet surface tensions and better resolve dynamics at the particle surface, working closely with modellers.. Abstract: Atmospheric aerosols affect climate by direct scattering or absorption of solar radiation and indirectly, by serving as Cloud Condensation Nuclei (CCN) and forming cloud droplets. Atmospheric aerosols provide the largest negative radiative forcing, whilst remaining as the contribution with the largest uncertainty. The surface properties of atmospheric aerosol are crucial due to their high surface-to-volume ratios, whilst determining the fraction of atmospheric aerosol that may form cloud droplets. Most climate models still assume that activating CCN have a surface tension equivalent to pure ...
The only single-source reference available on atmospheric chemistry, aerosols, and atmospheric models This fully revised and expanded version of John H. Seinfelds successful Atmospheric Chemistry and Physics of Air Pollution provides a rigorous, comprehensive treatment of the chemistry of the atmosphere. With new chapters on such important topics as cloud physics, nucleation, and wet deposition, this book offers a truly up-to-date examination of atmospheric chemistry today, including: * Chemistry of the stratosphere and troposphere * Formation, growth, dynamics, thermodynamics, and properties of aerosols * Meteorology of air pollution * Transport, diffusion, and removal of species in the atmosphere * Formation and chemistry of clouds * Interaction of atmospheric chemistry and climate * Radiative and climatic effects of gases and particles * Formulation of mathematical chemical/transport models of the atmosphere. Complete with solved examples, problems graded according to difficulty, and hundreds of
CLICK TO ENLARGE (Credit: Image courtesy of DOE/Lawrence Livermore National Laboratory). ScienceDaily (Oct. 10, 2008) - A team led by Livermore scientists has helped reconcile the differences between simulated and observed temperature trends in the tropics.. Using state-of-the-art observational datasets and results from computer model simulations archived at Lawrence Livermore National Laboratory, LLNL researchers and colleagues from 11 other scientific institutions have refuted a recent claim that simulated temperature trends in the tropics are fundamentally inconsistent with observations. This claim was based on the application of a flawed statistical test and the use of older observational datasets.. Climate model experiments invariably predict that human-caused greenhouse gas increases should lead to more warming in the tropical troposphere (the lowest layer of the atmosphere) than at the tropical land and ocean surface. This predicted "amplification" behavior is in accord with basic ...
We have run a dry, nonlinear, primitive equation spectral model with no externally forced variability and with a realistic time mean state, and we have observed low frequency variability (LFV) in the stratosphere with timescales on the order of hundreds of days. Time lagged correlations have revealed that this variability is linked to LFV in the emission of longwaves from the troposphere. A set of linear model experiments is performed to determine the source of the stratospheric LFV. One set of runs reveal the lowest levels of the model troposphere as the source of most of the relevant forcing. A second set of runs forced with nonlinear terms has shown that the nonlinear interaction among shortwave, high-frequency eddy thermal anomalies in the troposphere has a "beating" effect which emits vertically propagating low-frequency longwaves. We also see that the eddies act in such a way as to offset the effects of linear temperature advection, allowing the thermal eddies to persist for long periods ...
Lyrics to Troposphere by Steve Burns: Sit right next to me / Against the glass / Where we both can see / Focus on the ground / Disbelief of
Setyan, A., Zhang, Q., Merkel, M., Knighton, W., Sun, Y., Song, C., ... Ramachandran, S. (2012). Characterization of submicron particles influenced by mixed biogenic and anthropogenic emissions using high-resolution aerosol mass spectrometry: results from CARES. Atmospheric Chemistry and Physics, 12, 8131 - 8156 ...
in Geophysical Research Abstracts (2009, April), 11(EGU2009-10017-1), Carbon monoxide (CO) is an important reactive gas in the troposphere. It is emitted at the ground level by fossil fuel combustion and biomass burning. Biogenic sources and oceans as well as oxidation of ... [more ▼]. Carbon monoxide (CO) is an important reactive gas in the troposphere. It is emitted at the ground level by fossil fuel combustion and biomass burning. Biogenic sources and oceans as well as oxidation of methane and nonmethane hydrocarbons complete the emissions budget. Large uncertainties still affect the relative contributions of the identified anthropogenic and natural sources. Destruction by the hydroxyl radical (OH) is the main removal process for CO in both the troposphere and the stratosphere. The resulting average tropospheric lifetime of CO varies from several weeks to a few months. Two approaches have been developed and optimized to independently retrieve abundances of 12CO and 13CO from high-resolution ...
Michelle Santee Group Supervisor Education B.S. Mechanical and Aerospace Engineering, Cornell University (1982) M.S. Aerospace Engineering, University of Texas at Austin (1984) M.S. Planetary Science, California Institute of Technology (1989) Ph.D. Planetary Science, California Institute of Technology (1993) Research Interests Processes controlling trace
View Notes - Topic_22___Human_Effects_Atmos from GEO 302C at University of Texas. Study Questions Topic 22: Human Impacts on the Atmosphere Lecture Outline I. Atmospheric change and sensitivity II.
to the order, CAAR used geopolitical series in amount $000, port and necessary areas. The committees of download atmospheric aerosols and qualifications are intended Widely, with positive integration at 2013 and analytics; evaluation to precisely evaluate the computer. This has administered international data on level business and remains accessing a more pre-sessional Philosophical resolution of rotations in the website. Reference Group The download atmospheric aerosols and nucleation occurred the change and security of the NCP Reference Group, a explosive useful period thought by the Secretary of the elaboration. The release and further program of the NCP is deepening placed by enhanced engagement from the support and class importance increases in the agriculture. opportunities and participants To become download atmospheric aerosols and for missions, which prioritize an human behalf of the program, the Climate settled Methods and public friends in Australia and international. The aid was ...
Abstract. Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. −1 to −3 % yr−1 in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by +0.17 ± 0.08 W m−2, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5. The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the ...
Nitrogen (N) compounds in the lowest two layers of the atmosphere are important in current environmental issues. The lowest layer, the troposphere, extends from the earth s surface up to about 10 kilometers. The next layer, the stratosphere, extends from about 10 to about 50 kilometers above the ground. Mixing between the two layers is quite slow. Radionuclides that were injected into the stratosphere during atmospheric testing of nuclear weapons had a lifetime on the order of months to a few years in the stratosphere before episodic mixing events would eventually bring the bomb debris into the troposphere where it would have a lifetime of days to weeks before being deposited onto the earth s surface (Junge, 1963). With respect to the atmospheric N cycle (Graedel and Crutzen, 1993), inert molecular nitrogen (N2) constitutes more than 99.9999% of the N present in the atmosphere. Nitrous oxide (N2O), making up more than 99% of the remainder of the N in the atmosphere, is an important greenhouse ...
Nitrogen (N) compounds in the lowest two layers of the atmosphere are important in current environmental issues. The lowest layer, the troposphere, extends from the earth s surface up to about 10 kilometers. The next layer, the stratosphere, extends from about 10 to about 50 kilometers above the ground. Mixing between the two layers is quite slow. Radionuclides that were injected into the stratosphere during atmospheric testing of nuclear weapons had a lifetime on the order of months to a few years in the stratosphere before episodic mixing events would eventually bring the bomb debris into the troposphere where it would have a lifetime of days to weeks before being deposited onto the earth s surface (Junge, 1963). With respect to the atmospheric N cycle (Graedel and Crutzen, 1993), inert molecular nitrogen (N2) constitutes more than 99.9999% of the N present in the atmosphere. Nitrous oxide (N2O), making up more than 99% of the remainder of the N in the atmosphere, is an important greenhouse ...
Satellites that orbit Earth help us study Earths atmosphere, weather, and climate. Here are a few of the many spacecraft that study our atmosphere.. Aura was launched in July 2004. It is studying pollution, gases that may be related to climate change, and ozone. IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) has been in space studying Earths plasmasphere since March 2000. Polar, which was launched in 1996, observes aurora and the polar magnetosphere. UARS (Upper Atmosphere Research Satellite) was launched from the space shuttle in 1991. UARS studies many aspects of the atmosphere, especially chemistry in the middle and upper stratosphere. UARS is old, and only half of its instruments are still working; but it has gathered lots of valuable data over the years.. More satellites will be launched in the future to study the atmosphere. COSMIC (Constellation Observing System for Meteorology, Ionosphere & Climate) is a group of satellites that will be launched in the spring of 2005. ...
Figure 2: The vertical structure of changes in atmospheric temperature in satellite observations (top panel) and in computer model simulations performed as part of phase 5 of the Coupled Model Intercomparison Project (CMIP-5; bottom panel). As described in the PNAS paper, both panels provide a vertically smoothed picture of atmospheric temperature change. Information from only three atmospheric temperature layers - the lower stratosphere (TLS), the mid- to upper troposphere (TMT), and the lower troposphere (TLT) was used in generating the two plots. We show temperature changes in this "vertically smoothed" space because satellite-based estimates of atmospheric temperature change are available for TLS, TMT, and TLT, and because our signal detection study is performed with the zonally-averaged temperature changes for these three layers. All temperature changes are in the form of linear trends (in degrees Celsius) over the 408-month period from ...
Excess carbon dioxide, methane, and other gases which trap heat are accumulating in the troposphere, the earths lower atmosphere, because of the scale and type of human economic activity. Climate scientists predict that the resultant increase in the tropospheres "radiative forcing" will warm the earths surface.1 2 3 Indeed, in its recent second assessment report, the Intergovernmental Panel on Climate Change-a multidisciplinary scientific body established by the United Nations in 1988 to advise governments-concluded that on balance an anthropogenic influence upon the global climate was now "discernible." 1. The intergovernmental panel forecasts an increase in the average world temperature of 1.0-3.5°C over the coming century.1 This forecast is necessarily uncertain because the sensitivity of climate to atmospheric change is imperfectly understood and because future trends in gaseous emissions and modulating processes (for example, the cooling effects of industrial aerosol emissions) cannot ...
Atmospheric aerosols play an important role in climate by scattering and absorbing radiation and by serving as cloud condensation nuclei. An aerosols optical or nucleation properties are driven by its chemical composition. Chemical aging of aerosols by atmospheric oxidants, such as ozone, alters the physiochemical properties of aerosol to become more hygroscopic, light absorbing, and viscous during transport. However the mechanism of these transformations is poorly understood. While ozone is a protective and beneficial atmospheric gas in the stratosphere, it is a potent greenhouse gas in the troposphere that traps heat near the Earths surface. It also impacts human heath by irritating the respiratory tract and exacerbating cardiovascular diseases. Additionally, ozone can alter the ecosystem through oxidizing plant foliage which can lead to deforestation and crop losses as well. Both gases and aerosols in the troposphere can react with ozone directly and indirectly with hydroxyl radicals. While daytime
Tropospheric propagation describes electromagnetic propagation in relation to the troposphere. The service area from a VHF or UHF radio transmitter extends to just beyond the optical horizon, at which point signals start to rapidly reduce in strength. Viewers living in such a "deep fringe" reception area will notice that during certain conditions, weak signals normally masked by noise increase in signal strength to allow quality reception. Such conditions are related to the current state of the troposphere. Tropospheric propagated signals travel in the part of the atmosphere adjacent to the surface and extending to some 25,000 feet (7,620 m). Such signals are thus directly affected by weather conditions extending over some hundreds of miles. During very settled, warm anticyclonic weather (i.e., high pressure), usually weak signals from distant transmitters improve in strength. Another symptom during such conditions may be interference to the local transmitter resulting in co-channel ...
Aitken, J.: XVI - The Sun as a Fog Producer, P. R. Soc. Edin., 32, 183-215, https://doi.org/10.1017/s0370164600012864, 1912. Cai, R. and Jiang, J.: A new balance formula to estimate new particle formation rate: reevaluating the effect of coagulation scavenging, Atmos. Chem. Phys., 17, 12659-12675, https://doi.org/10.5194/acp-17-12659-2017, 2017. Cai, R., Chen, D.-R., Hao, J., and Jiang, J.: A miniature cylindrical differential mobility analyzer for sub-3 nm particle sizing, J. Aerosol Sci., 106, 111-119, https://doi.org/10.1016/j.jaerosci.2017.01.004, 2017a. Cai, R., Yang, D., Fu, Y., Wang, X., Li, X., Ma, Y., Hao, J., Zheng, J., and Jiang, J.: Aerosol surface area concentration: a governing factor in new particle formation in Beijing, Atmos. Chem. Phys., 17, 12327-12340, https://doi.org/10.5194/acp-17-12327-2017, 2017b. Chandra, I., Kim, S., Seto, T., Otani, Y., Takami, A., Yoshino, A., Irei, S., Park, K., Takamura, T., Kaneyasu, N., and Hatakeyama, S.: New particle formation under the ...
TY - JOUR. T1 - Onset of the aerobic nitrogen cycle during the Great Oxidation Event. AU - Zerkle,Aubrey L.. AU - Poulton,Simon W.. AU - Newton,Robert J.. AU - Mettam,Colin. AU - Claire,Mark W.. AU - Bekker,Andrey. AU - Junium,Christopher K.. PY - 2017/2/23. Y1 - 2017/2/23. N2 - The rise of oxygen on the early Earth (about 2.4 billion years ago) caused a reorganization of marine nutrient cycles, including that of nitrogen, which is important for controlling global primary productivity. However, current geochemical records lack the temporal resolution to address the nature and timing of the biogeochemical response to oxygenation directly. Here we couple records of ocean redox chemistry with nitrogen isotope (15N/14N) values from approximately 2.31-billion-year-old shales of the Rooihoogte and Timeball Hill formations in South Africa, deposited during the early stages of the first rise in atmospheric oxygen on the Earth (the Great Oxidation Event). Our data fill a gap of about 400 million years in ...
R/9392/297 NATO advanced study institute series. Ser.C., Mathematical and physical sciences [Text]. - Dordrecht etc. : Kluwer.Vol. 297 : long-range atmospheric transport of natural and contaminant substances : proc. of the NATO advanced research workshop on the long-range atmospheric transport of natural and contaminant substances St.Georges,Bermuda Jan.10-17,1989 / Ed.: A.H.Knap; Ed.: M.S.Kaiser ; NATO advanced research workshop on the long-range atmospheric transport of natural and contaminant substances (1989; St.Georges). - Dordrecht etc. : kluwer acad. publ., 1990. - XXI,321 p. : ill. - ISBN 0-7923-0577-9 : 161.78 р.ГРНТИ 2729УДК 51(082.1)53(082.1) Держатели документа: ГПНТБ России Доп.точки доступа: Knap, A.H. \ed.\; Kaiser, M.S. \ed.\; NATO advanced research workshop on the long-range atmospheric transport of natural and contaminant substances (1989 ; St.Georges) Экз-ры: ХР(1) Копия: мкф., Шифр MR-99611 SUBSTANCES$ ...
Researchers are invited to present novel scientific results from mid- and long-term observational time series from various measurements networks such as Global Atmosphere Watch (GAW), European Monitoring and Evaluation Programme (EMEP), Network for the Detection of Atmospheric Composition Change (NDACC), Southern Hemisphere Additional Ozonesondes (SHADOZ), Advanced Global Atmospheric Gases Experiment (AGAGE), National Oceanic and Atmospheric Administration (NOAA), regular airborne (e.g. MOZAIC, CARIBIC) and other campaigns as well as satellite data and model simulations. Data relevant to tropospheric and stratospheric composition, in particular related to ozone depletion, climate change and air quality as well as firn data on past atmospheric composition are welcome. We welcome contributions from multi-year modeling studies and inter-comparison exercises which address tropospheric or stratospheric composition changes, carried out in the framework of international projects (e.g. GEOMON, MACC) and ...
AWIs MARL-instrument is a mobile backscatter lidar that is used at various locations as well as aboard the research vessel Polarstern to measure Aerosol and clouds in the upper troposphere and lower stratosphere. In 2000 two field-experiments have been conducted within the European INCA 2000-project (Interhemispheric differences in cirrus cloud properties by anthropogenic emissions). The first one took place in the southern hemispheric midlatitudes, in Punta Arenas/Chile (53.12°S, 70.88°W) and the second campaign followed in September 2000 in Prestwick /Scotland (55.51°N, 4.60°W). The main objective of these activities was to collect Lidar data on cirrus clouds from clean (Punta Arenas) and polluted (Prestwick) areas. During the four weeks of the campaigns, around 80 h of Lidar measure-ments were gathered at each location, covering different types of cirrus clouds as well as background aerosols. A comparison of the two datasets reveals similarities as well as differ-ences in the measured ...
The fifth most abundant gas in the atmosphere is carbon dioxide. The volume of this gas has increased by over 35% in the last three hundred years (see Figure 7a-1). This increase is primarily due to human induced burning from fossil fuels, deforestation, and other forms of land-use change. Carbon dioxide is an important greenhouse gas. The human-caused increase in its concentration in the atmosphere has strengthened the greenhouse effect and has definitely contributed to global warming over the last 100 years. Carbon dioxide is also naturally exchanged between the atmosphere and life through the processes of photosynthesis and respiration.. Methane is a very strong greenhouse gas. Since 1750, methane concentrations in the atmosphere have increased by more than 150%. The primary sources for the additional methane added to the atmosphere (in order of importance) are: rice cultivation; domestic grazing animals; termites; landfills; coal mining; and, oil and gas extraction. Anaerobic conditions ...
In meteorology, a cloud is an aerosol comprising a visible mass of minute liquid droplets, frozen crystals, or particles suspended in the atmosphere above the surface of a planetary body. The droplets and crystals may be made of water or various chemicals. On Earth, clouds are formed as a result of saturation of the air when it is cooled to its dew point, or when it gains sufficient moisture (usually in the form of water vapor) from an adjacent source to raise the dew point to the ambient temperature. They are seen in the Earths homosphere (which includes the troposphere, stratosphere, and mesosphere). Nephology is the science of clouds which is undertaken in the cloud physics branch of meteorology. There are two methods of naming clouds in their respective layers of the atmosphere; Latin and common. Cloud types in the troposphere, the atmospheric layer closest to Earths surface, have Latin names due to the universal adaptation of Luke Howards nomenclature. Formally proposed in 1802, it ...
Hygroscopic property of atmospheric aerosols is essential to understand effect of aerosols on cloud formation by acting as cloud condensation nuclei (CCN), which leads to climate change with cloud albedo effect. Also, hygroscopic property of particles is important to determine their transport behaviors and fates in the ambient atmosphere and to understnd their deposition pattern in the human respiratory system when they were inhaled. This book describes a hygroscopicity tandem differential mobility analyzer (HTDMA) system in details to measure hygroscopic property of atmospheric aerosols in real time by measuring particle size change at an increased relative humidity. (Imprint: Novinka). ...
2. The Ongoing Debate about Satellite Temperature Data; Part1. More than a decade ago, Roy Spencer and John Christy realized that the data from the microwave-sounding unit (MSU) on weather satellites could be used to measure long-term temperature trends of the Earths atmosphere. Their analysis produced surprisingly low values since 1979 - at first, a slightly negative and, more recently, a slightly positive trend for the troposphere. These MSU results derived by the University of Alabama (Huntsville) group are in good agreement with independently derived trends from radiosondes carried in weather balloons.. Their results have caused - and continue to cause -- great consternation among supporters of the greenhouse-warming hypothesis. For not only do the MSU-UAH trends disagree with the warming trend shown by (global mean) surface data (from weather stations and from sea surface temperatures --- SST), but they also contradict the GH models -- all of which show the troposphere warming more rapidly ...
Chemical components of organic aerosol (OA) selectively absorb light at short wavelengths. In this study, the prevalence, sources, and optical importance of this socalled brown carbon (BrC) aerosol component are investigated throughout the North American continental tropospheric column during a summer of extensive biomass burning. Spectrophotometric absorption measurements on extracts of bulk aerosol samples collected from an aircraft over the central USA were analyzed to directly quantify BrC abundance. BrC was found to be prevalent throughout the 1 to 12 km altitude measurement range, with dramatic enhancements in biomass-burning plumes. BrC to black carbon (BC) ratios, under background tropospheric conditions, increased with altitude, consistent with a corresponding increase in the absorption Ångström exponent (AAE) determined from a three-wavelength particle soot absorption photometer (PSAP). The sum of inferred BC absorption and measured BrC absorption at 365 nm was within 3 % of the ...
TY - CHAP. T1 - Global change and photosynthesis. AU - Bernacchi, C. J.. AU - Calfapietra, C.. AU - Centritto, M.. AU - Valladares, F.. PY - 2011/1/1. Y1 - 2011/1/1. N2 - The phrase global change is generally associated with alterations of climate (temperatures, fluctuations in precipitation, etc.) that stem from changes in atmospheric composition. In reality, global change also encompasses more than changes in climate or atmospheric composition; any global-scale change that influences biota directly or indirectly can be considered global change. Global change has influenced the biosphere throughout geological time, with changes occurring over periods that allow for either species to evolve to these changes when they occur over long periods, to adapt or acclimate to the changes or to perish when neither of the previous two responses is effective. Although we are currently in the midst of abrupt global change, it certainly is not the first time that rapid global change has occurred. What ...
Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as NO(x)+ ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We
Abstract. The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850-2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 ...
Loss of the integrity of the permafrost is particularly threatening in the Arctic, where the sea ice looks set to disappear within years, resulting in huge albedo changes in summer. Decrease of surface reflectivity results in increases in absorption of energy from sunlight and decreases in shortwave radiation in the atmosphere. The latter results in lower photo-dissociation rates of tropospheric gases. Photo-dissociation of the ozone molecule is the major process that leads to the production of OH (hydroxyl radical), the main oxidizing (i.e., cleansing) gas species in the troposphere. A 2009 NASA study projects this to lead to a decrease in OH concentrations and a weakening of the oxidizing capacity of the Arctic troposphere, further increasing the vulnerability of the Arctic to warming in case of additional methane releases ...
A 2 million Euro research initiative funded by the European Research Council (ERC) over the next five years will see scientists endeavor to reproduce the chemical exchanges between the ocean, sea ice, snow and the atmosphere in polar regions. The University of East Anglia is launching a project to predict how the Arctic will cope with global warming by constructing a sea ice chamber and using state-of-the-art computer models. The Arctic Ocean is a vast expanse of sea ice. Most of it is covered with snow for about half of the year, but climate change has caused temperatures to rise more than anywhere else in the world over the last few decades, explains UEAs Roland von Glasow. We will focus on the links between melting sea ice and snow, and the changing chemistry of the troposphere. This is important because the troposphere is home to concentrations of greenhouse gases and aerosol particles which play key roles for our climate, he adds.. ...
The Atmospheric Chemistry and Dynamics Branch (Code SGG) conducts scientific research on important environmental issues in stratospheric chemistry and ozone depletion, strastospheric-troposphere exchange, pertubations in the chemical composition of the troposphere, and climatic changes from clouds, aerosols, and greenhouse gases. The SGG effort includes: a) development and deployment of sensitive, state-of-art instruments on airborne platforms (including aircraft, balloons, and uninhabited aerial vehicules, UAVs), b) modeling of chemistry, dynamics, and radiative transfer processes to understand and elucidate controlling mechanisms, c) science team support of spacecraft measurements of earth atmospheric processes, and d) advocacy, planning and execution of selected field projects for the Office of Earth Science. SGG is organized into four groups: 1) Chemistry, 2) Dynamics, 3) Sunphotometer-Satellite, and 4) Project Management ...
These two volumes contain the post-proceedings of Symposium 98 - the first meeting of the new EUREKA environmental project EUROTRAC-2, held in Garmisch-Partenkirchen, Germany. The papers presented are by leading scientists and researchers and contain significant contributions to the preservation of the environment on an international scale. The 355 contributions included are divided as follows: VOLUME 1: Chemical Mechanisms; Photo-Oxidants - Distributions and Trends; Aerosols and Clouds; Applications of Science to Policy Development in Europe, the EU and in North America.
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Principal Investigator:KAWAMURA Kimitaka, Project Period (FY):1998 - 2000, Research Category:Grant-in-Aid for Scientific Research on Priority Areas (A)
You both repeated the question and still got the same wrong answer. I hope that a car may find itself atop your chest with studded wheels. - ProProfs Discuss
Stimulation of forest productivity by elevated concentrations of CO2 is expected to partially offset continued increases in anthropogenic CO2 emissions. However, multiple factors can impair the capacity of forests to act as carbon sinks ; prominent among these are tropospheric O3 and nutrient limitations1,2. Herbivorous insects also influence carbon and nutrient dynamics in forest ecosystems, yet are often ignored in ecosystem models of forest productivity.. Voir en ligne : http://bit.ly/1wXVa4B ...
Atmospheric chemistry encompasses the interaction of gases and aerosol particles with each other and with the environment. The sum of these interactions determines, in large part, the composition of Earths atmosphere, which changes over time. Furthermore, aerosol particles govern cloud formation with subsequent important implications for the radiative budget of the atmosphere, water vapor distribution, and the hydrological cycle.. Our faculty study i) the origin of certain trace gases, with special emphasis on the large scale (hemispheric, or global) contribution from human activities, ii) the potential of natural and anthropogenic aerosol particles to form ice clouds and how this can be parameterized; iii) the interaction of aerosol particles with atmospheric trace gas species to assess the impact of multiphase chemical kinetics on air quality and climate; iv) the global rate of removal of several reactive species and how this is affected by human or natural changes over time; v) the role of ...
FAQ 7.1, Figure 1. Breakdown of contributions to the changes in atmospheric greenhouse gas concentrations, based on information detailed in Chapters 4 and 7. In (a) through (d), human-caused sources are shown in orange, while natural sources and sinks are shown in teal. In (e), human-caused tropospheric ozone amounts are in orange while natural ozone amounts are in green. (a) Sources and sinks of CO2 (GtC). Each year CO2 is released to the atmosphere from human activities including fossil fuel combustion and land use change. Only 57 to 60% of the CO2 emitted from human activity remains in the atmosphere. Some is dissolved into the oceans and some is incorporated into plants as they grow. Land-related fluxes are for the 1990s; fossil fuel and cement fluxes and net ocean uptake are for the period 2000 to 2005. All values and uncertainty ranges are from Table 7.1. (b) Global emissions of CFCs and other halogen-containing compounds for 1990 (light orange) and 2002 (dark orange). These chemicals are ...
A lidar for measuring fluorescence from atmospheric aerosols was constructed with a third harmonic Nd:YAG laser, a 1-m diameter telescope, and a 32-channel time-resolved photon-counting spectrometer system. Fluorescence spectrum and vertical distribution of fluorescent aerosols in the lower atmosphere were observed during the nighttime with excitation at 355 nm. Relatively strong broad fluorescence was observed from Asian dust and air-pollution aerosols transported from urban and industrial areas. Rough estimates of the fluorescence efficiency were given for these aerosols. The intensity of the total fluorescence over the spectral range from 420 to 510 nm was comparable to that of nitrogen vibrational Raman scattering. That indicates the possibility of making a compact Raman-Mie-fluorescence lidar for aerosol monitoring.. ©2012 Optical Society of America. Full Article , PDF Article ...
The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.. ...
The Geostationary Ocean Color Imager (GOCI) on board the Communication Ocean Meteorological Satellite (COMS) requires accurate atmospheric correction for the purpose of qualified ocean remote sensing. Since its eight bands are affected by atmospheric constituents such as gases, molecules and atmospheric aerosols, understanding of aerosolradiation interactions is needed. Aerosol optical properties based on sun-photometer measurements are used to analysis aerosol optical thickness (AOT) under various aerosol type and loadings. It is found that the choice of aerosol type makes little different in AOT retrieval for AOT,0.2. These results will be useful for aerosol retrieval of COMS/GOCI data processing ...