Nitrogen and Phosphorous Flow in Atlantic Forest Covered Watersheds on the Oceanic and Continental Slopes at Serra dos Órgãos mountain, Southeast of Brazil

NASA Astrophysics Data System (ADS)

Vidal, M. M.; De Souza, P.; De Mello, W. Z.; Damaceno, I.; Bourseau, L.; Rodrigues, R. D. A.; Mattos, B. B.

2017-12-01

Concentration of nutrients above natural levels are found even at remote or protected environments due to atmospheric transportation from biomass burning emissions, urban and industrial areas. This study evaluate N and P atmospheric deposition at the oceanic and continental slopes of Serra dos Órgãos mountain, which are influenced by the pollutants emission from the Metropolitan Region of Rio de Janeiro. Flux of dissolved forms of N and P were measured in three watersheds in headwaters of Piabanha basin, southeastern Brazil, to understand the dynamics of the biogeochemical processes of these elements, related to anthropic influences of atmospheric inputs and export via stream flow. Samples of bulk precipitation (weekly; n=47) and stream water (monthly; n=13) were collected along one year (Sept 2014 - Sept 2015). During that period the annual rainfall in the oceanic slope (2163 mm) was the double of the continental one. It is important to stress that the rainfall in the oceanic slope was 13 % and 28% in 2014/15, respectively, lower than the long term average. Atmospheric deposition of total dissolved nitrogen (TDN) on the oceanic and continental slopes were, respectively, 15 and 8.6 kg N ha-1 year-1. The TDN outputs by stream water were 5-7 times lower in oceanic slope and 28 times lower on the continental one. The relative contribution of dissolved organic nitrogen (DON; 65%-70%) was higher than the one of dissolved inorganic nitrogen (DIN; 30-35%) to TDN deposition. Atmospheric deposition of total dissolved phosphorus (TDP) in oceanic and continental slopes were 1.4 and 0.95 kg P ha-1 year-1. Dissolved Organic Phosphorus (DOP; 89-96%) was higher than the inorganic one (PO43-; 5-11%). TDP outputs were 2-4 times lower, regarding to atmospheric contribution. The contribution of DOP (73-77 %) was higher than DIP (23-27 %). Results show variations in quantities and forms of N and P species due to natural and anthropogenic processes which contribute to the cycling of these elements in the Serra dos Órgãos. TDN atmospheric contribution on oceanic slope, as well as the DON/DIN ratio, was higher than found on previous studies on the same area.The differences between inputs and outputs of N and P balance can be attributed to factors, including biogeochemical and physical processes, and to an underestimation of stream flows in annual scale.

Energetic particle influences in Earth's atmosphere

NASA Astrophysics Data System (ADS)

Aplin, Karen; Harrison, R. Giles; Nicoll, Keri; Rycroft, Michael; Briggs, Aaron

2016-04-01

Energetic particles from outer space, known as galactic cosmic rays, constantly ionise the entire atmosphere. During strong solar storms, solar energetic particles can also reach the troposphere and enhance ionisation. Atmospheric ionisation generates cluster ions. These facilitate current flow in the global electric circuit, which arises from charge separation in thunderstorms driven by meteorological processes. Energetic particles, whether solar or galactic in origin, may influence the troposphere and stratosphere through a range of different mechanisms, each probably contributing a small amount. Some of the suggested processes potentially acting over a wide spatial area in the troposphere include enhanced scavenging of charged aerosol particles, modification of droplet or droplet-droplet behavior by charging, and the direct absorption of infra-red radiation by the bending and stretching of hydrogen bonds inside atmospheric cluster-ions. As well as reviewing the proposed mechanisms by which energetic particles modulate atmospheric properties, we will also discuss new instrumentation for measurement of energetic particles in the atmosphere.

New insight into atmospheric mercury emissions from zinc smelters using mass flow analysis.

PubMed

Wu, Qingru; Wang, Shuxiao; Hui, Mulin; Wang, Fengyang; Zhang, Lei; Duan, Lei; Luo, Yao

2015-03-17

The mercury (Hg) flow paths from three zinc (Zn) smelters indicated that a large quantity of Hg, approximately 38.0-57.0% of the total Hg input, was stored as acid slag in the landfill sites. Approximately 15.0-27.1% of the Hg input was emitted into water or stored as open-dumped slags, and 3.3-14.5% of the Hg input ended in sulfuric acid. Atmospheric Hg emissions, accounting for 1.4-9.6% of the total Hg input, were from both the Zn production and waste disposal processes. Atmospheric Hg emissions from the waste disposal processes accounted for 40.6, 89.6, and 94.6% of the total atmospheric Hg emissions of the three studied smelters, respectively. The Zn production process mainly contributed to oxidized Hg (Hg2+) emissions, whereas the waste disposal process generated mostly elemental Hg (Hg0) emissions. When the emissions from these two processes are considered together, the emission proportion of the Hg2+ mass was 51, 46, and 29% in smelters A, B, and C, respectively. These results indicated that approximately 10.8±5.8 t of atmospheric Hg emissions from the waste disposal process were ignored in recent inventories. Therefore, the total atmospheric Hg emissions from the Zn industry of China should be approximately 50 t.

Atmospheric science and power production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randerson, D.

1984-07-01

This is the third in a series of scientific publications sponsored by the US Atomic Energy Commission and the two later organizations, the US Energy Research and Development Adminstration, and the US Department of Energy. The first book, Meteorology and Atomic Energy, was published in 1955; the second, in 1968. The present volume is designed to update and to expand upon many of the important concepts presented previously. However, the present edition draws heavily on recent contributions made by atmospheric science to the analysis of air quality and on results originating from research conducted and completed in the 1970s. Specialmore » emphasis is placed on how atmospheric science can contribute to solving problems relating to the fate of combustion products released into the atmosphere. The framework of this book is built around the concept of air-quality modeling. Fundamentals are addressed first to equip the reader with basic background information and to focus on available meteorological instrumentation and to emphasize the importance of data management procedures. Atmospheric physics and field experiments are described in detail to provide an overview of atmospheric boundary layer processes, of how air flows around obstacles, and of the mechanism of plume rise. Atmospheric chemistry and removal processes are also detailed to provide fundamental knowledge on how gases and particulate matter can be transformed while in the atmosphere and how they can be removed from the atmosphere. The book closes with a review of how air-quality models are being applied to solve a wide variety of problems. Separate analytics have been prepared for each chapter.« less

Contribution of Primary and Secondary Sources to Organic Aerosol and PM2.5 at SEARCH Network Sites

EPA Science Inventory

Chemical tracer methods for determining contributions to primary organic aerosol (POA) are fairly well established, whereas similar techniques for secondary organic aerosol (SOA), inherently complicated by time-dependent atmospheric processes, are only beginning to be studied. La...

Land Breeze and Thermals: A Scale Threshold to Distinguish Their Effects

Treesearch

Yongqiang Liu

2005-01-01

Land breeze is a type of mesoscale circulation developed due to thermal forcing over a heterogeneous landscape. It can contribute to atmospheric dynamic and hydrologic processes through affecting heat and water fluxes on the land-atmosphere interface and generating shallow convective precipitation. If the scale of the landscape heterogeneity is smaller than a certain...

Honors

NASA Astrophysics Data System (ADS)

Anonymous

2012-10-01

Many AGU members are among the American Meteorological Society's (AMS) 2013 honorary members, awardees, lecturers, and fellows. Among the AMS honorary members is Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at the Massachusetts Institute of Technology (MIT). Dennis Hartmann, of the University of Washington, Seattle, is the recipient of AMS's Carl-Gustaf Rossby Research Medal "for significant contributions to the synthesis of knowledge of radiative and dynamical processes leading to a deeper understanding of the climate system." R. Alan Plumb, professor of meteorology at MIT, receives the Jule G. Charney Award "for fundamental contributions to the understanding of geophysical fluid dynamics, stratospheric dynamics, chemical transport, and the general circulation of the atmosphere and oceans." The Verner E. Suomi Award has been given to Richard Johnson, professor of atmospheric science at Colorado State University, Fort Collins, "for exquisite design of rawinsonde networks in field campaigns and insightful analysis of interactions between convective clouds and the largescale atmospheric circulation." W. Kendall Melville, professor of oceanography at the Scripps Institution of Oceanography, University of California, San Diego, has been awarded the Sverdrup Gold Medal Award "for pioneering contributions in advancing knowledge on the role of surface wave breaking and related processes in air-sea interaction." AMS announced that Laurence Armi, also a professor of oceanography at Scripps, is recipient of the Henry Stommel Research Award "for his deeply insightful studies of stratified flow, his pioneering work on boundary mixing and other turbulent mechanisms."

Atmospheric footprint of the recent warming slowdown

PubMed Central

Liu, Bo; Zhou, Tianjun

2017-01-01

Growing body of literature has developed to detect the role of ocean heat uptake and transport in the recent warming slowdown between 1998–2013; however, the atmospheric footprint of the slowdown in dynamical and physical processes remains unclear. Here, we divided recent decades into the recent hiatus period and the preceding warming period (1983–1998) to investigate the atmospheric footprint. We use a process-resolving analysis method to quantify the contributions of different processes to the total temperature changes. We show that the increasing rate of global mean tropospheric temperature was also reduced during the hiatus period. The decomposed trends due to physical processes, including surface albedo, water vapour, cloud, surface turbulent fluxes and atmospheric dynamics, reversed the patterns between the two periods. The changes in atmospheric heat transport are coupled with changes in the surface latent heat flux across the lower troposphere (below approximately 800 hPa) and with cloud-related processes in the upper troposphere (above approximately 600 hPa) and were underpinned by strengthening/weakening Hadley Circulation and Walker Circulation during the warming/hiatus period. This dynamical coupling experienced a phase transition between the two periods, reminding us of the importance of understanding the atmospheric footprint, which constitutes an essential part of internal climate variability. PMID:28084457

Preface: MHD wave phenomena in the solar interior and atmosphere

NASA Astrophysics Data System (ADS)

Fedun, Viktor; Srivastava, A. K.

2018-01-01

The Sun is our nearest star and this star produces various plasma wave processes and energetic events. These phenomena strongly influence interplanetary plasma dynamics and contribute to space-weather. The understanding of solar atmospheric dynamics requires hi-resolution modern observations which, in turn, further advances theoretical models of physical processes in the solar interior and atmosphere. In particular, it is essential to connect the magnetohydrodynamic (MHD) wave processes with the small and large-scale solar phenomena vis-a-vis transport of energy and mass. With the advent of currently available and upcoming high-resolution space (e.g., IRIS, SDO, Hinode, Aditya-L1, Solar-C, Solar Orbiter), and ground-based (e.g., SST, ROSA, NLST, Hi-C, DKIST, EST, COSMO) observations, solar physicists are able to explore exclusive wave processes in various solar magnetic structures at different spatio-temporal scales.

Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks.

PubMed

Canadell, Josep G; Le Quéré, Corinne; Raupach, Michael R; Field, Christopher B; Buitenhuis, Erik T; Ciais, Philippe; Conway, Thomas J; Gillett, Nathan P; Houghton, R A; Marland, Gregg

2007-11-20

The growth rate of atmospheric carbon dioxide (CO(2)), the largest human contributor to human-induced climate change, is increasing rapidly. Three processes contribute to this rapid increase. Two of these processes concern emissions. Recent growth of the world economy combined with an increase in its carbon intensity have led to rapid growth in fossil fuel CO(2) emissions since 2000: comparing the 1990s with 2000-2006, the emissions growth rate increased from 1.3% to 3.3% y(-1). The third process is indicated by increasing evidence (P = 0.89) for a long-term (50-year) increase in the airborne fraction (AF) of CO(2) emissions, implying a decline in the efficiency of CO(2) sinks on land and oceans in absorbing anthropogenic emissions. Since 2000, the contributions of these three factors to the increase in the atmospheric CO(2) growth rate have been approximately 65 +/- 16% from increasing global economic activity, 17 +/- 6% from the increasing carbon intensity of the global economy, and 18 +/- 15% from the increase in AF. An increasing AF is consistent with results of climate-carbon cycle models, but the magnitude of the observed signal appears larger than that estimated by models. All of these changes characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing.

Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks

PubMed Central

Canadell, Josep G.; Le Quéré, Corinne; Raupach, Michael R.; Field, Christopher B.; Buitenhuis, Erik T.; Ciais, Philippe; Conway, Thomas J.; Gillett, Nathan P.; Houghton, R. A.; Marland, Gregg

2007-01-01

The growth rate of atmospheric carbon dioxide (CO2), the largest human contributor to human-induced climate change, is increasing rapidly. Three processes contribute to this rapid increase. Two of these processes concern emissions. Recent growth of the world economy combined with an increase in its carbon intensity have led to rapid growth in fossil fuel CO2 emissions since 2000: comparing the 1990s with 2000–2006, the emissions growth rate increased from 1.3% to 3.3% y−1. The third process is indicated by increasing evidence (P = 0.89) for a long-term (50-year) increase in the airborne fraction (AF) of CO2 emissions, implying a decline in the efficiency of CO2 sinks on land and oceans in absorbing anthropogenic emissions. Since 2000, the contributions of these three factors to the increase in the atmospheric CO2 growth rate have been ≈65 ± 16% from increasing global economic activity, 17 ± 6% from the increasing carbon intensity of the global economy, and 18 ± 15% from the increase in AF. An increasing AF is consistent with results of climate–carbon cycle models, but the magnitude of the observed signal appears larger than that estimated by models. All of these changes characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing. PMID:17962418

Parmeterization of spectra

NASA Technical Reports Server (NTRS)

Cornish, C. R.

1983-01-01

Following reception and analog to digital conversion (A/D) conversion, atmospheric radar backscatter echoes need to be processed so as to obtain desired information about atmospheric processes and to eliminate or minimize contaminating contributions from other sources. Various signal processing techniques have been implemented at mesosphere-stratosphere-troposphere (MST) radar facilities to estimate parameters of interest from received spectra. Such estimation techniques need to be both accurate and sufficiently efficient to be within the capabilities of the particular data-processing system. The various techniques used to parameterize the spectra of received signals are reviewed herein. Noise estimation, electromagnetic interference, data smoothing, correlation, and the Doppler effect are among the specific points addressed.

Planetary Magnetic Fields and Climate Evolution

NASA Astrophysics Data System (ADS)

Brain, D. A.; Leblanc, F.; Luhmann, J. G.; Moore, T. E.; Tian, F.

We explore the possible connections between magnetic fields and climate at the terrestrial bodies Venus, Earth, Mars, and Titan. Magnetic fields are thought to have negligible effects on the processes that change a planet's climate, except for processes that alter the abundance of atmospheric gases. Particles can be added or removed at the top of an atmosphere, where collisions are infrequent and a more substantial fraction of particles are ionized (and therefore subject to magnetic forces) than at lower altitudes. The absence of a global magnetic field at Mars for much of its history may have contributed to the removal of a substantial fraction of its atmosphere to space. The persistence of a global magnetic field should have decreased both ionization and removal of atmospheric ions by several processes, and may have indirectly decreased the loss rate of neutral particles as well. While it is convenient to think of magnetic fields as shields for planetary atmospheres from impinging plasma (such as the solar wind), observations of ions escaping from Earth's polar cusp regions suggest that magnetic shielding effects may not be as effective as previously thought. One explanation that requires further testing is that magnetic fields transfer momentum and energy from incident plasma to localized regions of the atmosphere, resulting in similar (or possibly greater) escape rates than if the momentum and energy were imparted more globally to the atmosphere in the absence of a magnetic field. Trace gases can be important for climate despite their low relative abundance in planetary atmospheres. At Venus, removal of O+ over the history of the planet has likely contributed to the loss of water from the atmosphere, leading to a runaway greenhouse situation and having implications for the chemistry of atmosphere-surface interactions. Conversely, Titan's robust atmospheric chemistry may result from the addition of trace amounts of oxygen from Saturn's magnetosphere, which then participate in chemical reactions that produce carbon monoxide (CO) and carbon dioxide (CO2). Models of the entire atmosphere system (including planetary plasma interactions) should continue to shed light on the connections between magnetic fields and climate, as well as models that consider a single planetary body in both magnetized and unmagnetized states. Future measurements, such as those that will be made by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft to Mars, will provide better constraints on the importance of magnetic fields in the evolution of atmospheres.

Dynamical ocean-atmospheric drivers of floods and droughts

NASA Astrophysics Data System (ADS)

Perdigão, Rui A. P.; Hall, Julia

2014-05-01

The present study contributes to a better depiction and understanding of the "facial expression" of the Earth in terms of dynamical ocean-atmospheric processes associated to both floods and droughts. For this purpose, the study focuses on nonlinear dynamical and statistical analysis of ocean-atmospheric mechanisms contributing to hydrological extremes, broadening the analytical hydro-meteorological perspective of floods and hydrological droughts to driving mechanisms and feedbacks at the global scale. In doing so, the analysis of the climate-related causality of hydrological extremes is not limited to the synoptic situation in the region where the events take place. Rather, it goes further in the train of causality, peering into dynamical interactions between planetary-scale ocean and atmospheric processes that drive weather regimes and influence the antecedent and event conditions associated to hydrological extremes. In order to illustrate the approach, dynamical ocean-atmospheric drivers are investigated for a selection of floods and droughts. Despite occurring in different regions with different timings, common underlying mechanisms are identified for both kinds of hydrological extremes. For instance, several analysed events are seen to have resulted from a large-scale atmospheric situation consisting on standing planetary waves encircling the northern hemisphere. These correspond to wider vortices locked in phase, resulting in wider and more persistent synoptic weather patterns, i.e. with larger spatial and temporal coherence. A standing train of anticyclones and depressions thus encircled the mid and upper latitudes of the northern hemisphere. The stationary regime of planetary waves occurs when the mean eastward zonal flow decreases up to a point in which it no longer exceeds the westward phase propagation of the Rossby waves produced by the latitude-varying Coriolis effect. The ocean-atmospheric causes for this behaviour and consequences on hydrological extremes are investigated and the findings supported with spatiotemporal geostatistical analysis and nonlinear geophysical models. Overall, the study provides a three-fold contribution to the research on hydrological extremes: Firstly, it improves their physical attribution by better understanding the dynamical reasons behind the meteorological drivers. Secondly, it brings out fundamental early warning signs for potential hydrological extremes, by bringing out global ocean-atmospheric features that manifest themselves much earlier than the regional weather patterns. Thirdly, it provides tools for addressing and understanding hydrological regime changes at wider spatiotemporal scales, by providing links to planetary-scale dynamical processes that play a crucial role in multi-decadal global climate variability.

Global Biology Research Program: Biogeochemical Processes in Wetlands

NASA Technical Reports Server (NTRS)

Bartlett, D. S. (Editor)

1984-01-01

The results of a workshop examining potential NASA contributions to research on wetland processes as they relate to global biogeochemical cycles are summarized. A wetlands data base utilizing remotely sensed inventories, studies of wetland/atmosphere exchange processes, and the extrapolation of local measurements to global biogeochemical cycling processes were identified as possible areas for NASA support.

On Mars' atmospheric sputtering after MAVEN first two years

NASA Astrophysics Data System (ADS)

Leblanc, F.; Modolo, R.; Curry, S.; Luhmann, J. G.; Lillis, R.; Chaufray, J. Y.; Hara, T.; McFadden, J.; Halekas, J.; Eparvier, F.; Larson, D.; Connerney, J.; Jakosky, B.

2017-09-01

Mars may have lost a significant part of its atmosphere into space along its history, in particular since the end of its internal dynamo, 4.1 Gyr ago. The sputtering of the atmosphere by precipitating planetary picked up ions accelerated by the solar wind is one of the processes that could have significantly contributed to this atmospheric escape. We here present a two years base analysis of MAVEN observation of the precipitating flux, in particular the dependency of the precipitating intensity with solar zenith angle and used this measurement to model the expected escape rate and exosphere induced by this precipitation.

Atmospheric Quantum Channels with Weak and Strong Turbulence.

PubMed

Vasylyev, D; Semenov, A A; Vogel, W

2016-08-26

The free-space transfer of high-fidelity optical signals between remote locations has many applications, including both classical and quantum communication, precision navigation, clock synchronization, etc. The physical processes that contribute to signal fading and loss need to be carefully analyzed in the theory of light propagation through the atmospheric turbulence. Here we derive the probability distribution for the atmospheric transmittance including beam wandering, beam shape deformation, and beam-broadening effects. Our model, referred to as the elliptic beam approximation, applies to weak, weak-to-moderate, and strong turbulence and hence to the most important regimes in atmospheric communication scenarios.

Honors

NASA Astrophysics Data System (ADS)

2012-10-01

Many AGU members are among the American Meteorological Society's (AMS) 2013 honorary members, awardees, lecturers, and fellows. Among the AMS honorary members is Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at the Massachusetts Institute of Technology (MIT). Dennis Hartmann, of the University of Washington, Seattle, is the recipient of AMS's Carl-Gustaf Rossby Research Medal “for significant contributions to the synthesis of knowledge of radiative and dynamical processes leading to a deeper understanding of the climate system.” R. Alan Plumb, professor of meteorology at MIT, receives the Jule G. Charney Award “for fundamental contributions to the understanding of geophysical fluid dynamics, stratospheric dynamics, chemical transport, and the general circulation of the atmosphere and oceans.” The Verner E. Suomi Award has been given to Richard Johnson, professor of atmospheric science at Colorado State University, Fort Collins, “for exquisite design of rawinsonde networks in field campaigns and insightful analysis of interactions between convective clouds and the largescale atmospheric circulation.” W. Kendall Melville, professor of oceanography at the Scripps Institution of Oceanography, University of California, San Diego, has been awarded the Sverdrup Gold Medal Award “for pioneering contributions in advancing knowledge on the role of surface wave breaking and related processes in air-sea interaction.” AMS announced that Laurence Armi, also a professor of oceanography at Scripps, is recipient of the Henry Stommel Research Award “for his deeply insightful studies of stratified flow, his pioneering work on boundary mixing and other turbulent mechanisms.”

Chemical evolution on Titan: comparisons to the prebiotic earth.

PubMed

Clarke, D W; Ferris, J P

1997-06-01

Models for the origin of Titan's atmosphere, the processing of the atmosphere and surface and its exobiological role are reviewed. Titan has gained widespread acceptance in the origin of life field as a model for the types of evolutionary processes that could have occurred on prebiotic Earth. Both Titan and Earth possess significant atmospheres (> or = 1 atm) composed mainly of molecular nitrogen with smaller amounts of more reactive species. Both of these atmospheres are processed primarily by solar ultraviolet light with high energy particles interactions contributing to a lesser extent. The products of these reactions condense or are dissolved in other atmospheric species (aerosols/clouds) and fall to the surface. There these products may have been further processed on Titan and the primitive Earth by impacting comets and meteorites. While the low temperatures on Titan (approximately 72-180 K) preclude the presence of permanent liquid water on the surface, it has been suggested that tectonic activity or impacts by meteors and comets could produce liquid water pools on the surface for thousands of years. Hydrolysis and oligomerization reactions in these pools might form chemicals of prebiological significance. Other direct comparisons between the conditions on present day Titan and those proposed for prebiotic Earth are also presented.

Use of high-volume outdoor smog chamber photo-reactors for studying physical and chemical atmospheric aerosol formation and composition

NASA Astrophysics Data System (ADS)

Borrás, E.; Ródenas, M.; Vera, T.; Muñoz, A.

2015-12-01

The atmospheric particulate matter has a large impact on climate, biosphere behaviour and human health. Its study is complex because of large number of species are present at low concentrations and the continuous time evolution, being not easily separable from meteorology, and transport processes. Closed systems have been proposed by isolating specific reactions, pollutants or products and controlling the oxidizing environment. High volume simulation chambers, such as EUropean PHOtoREactor (EUPHORE), are an essential tool used to simulate atmospheric photochemical reactions. This communication describes the last results about the reactivity of prominent atmospheric pollutants and the subsequent particulate matter formation. Specific experiments focused on organic aerosols have been developed at the EUPHORE photo-reactor. The use of on-line instrumentation, supported by off-line techniques, has provided well-defined reaction profiles, physical properties, and up to 300 different species are determined in particulate matter. The application fields include the degradation of anthropogenic and biogenic pollutants, and pesticides under several atmospheric conditions, studying their contribution on the formation of secondary organic aerosols (SOA). The studies performed at the EUPHORE have improved the mechanistic studies of atmospheric degradation processes and the knowledge about the chemical and physical properties of atmospheric particulate matter formed during these processes.

Maximum entropy production in environmental and ecological systems.

PubMed

Kleidon, Axel; Malhi, Yadvinder; Cox, Peter M

2010-05-12

The coupled biosphere-atmosphere system entails a vast range of processes at different scales, from ecosystem exchange fluxes of energy, water and carbon to the processes that drive global biogeochemical cycles, atmospheric composition and, ultimately, the planetary energy balance. These processes are generally complex with numerous interactions and feedbacks, and they are irreversible in their nature, thereby producing entropy. The proposed principle of maximum entropy production (MEP), based on statistical mechanics and information theory, states that thermodynamic processes far from thermodynamic equilibrium will adapt to steady states at which they dissipate energy and produce entropy at the maximum possible rate. This issue focuses on the latest development of applications of MEP to the biosphere-atmosphere system including aspects of the atmospheric circulation, the role of clouds, hydrology, vegetation effects, ecosystem exchange of energy and mass, biogeochemical interactions and the Gaia hypothesis. The examples shown in this special issue demonstrate the potential of MEP to contribute to improved understanding and modelling of the biosphere and the wider Earth system, and also explore limitations and constraints to the application of the MEP principle.

Estimating global natural wetland methane emissions using process modelling: spatio-temporal patterns and contributions to atmospheric methane fluctuations

USGS Publications Warehouse

Zhu, Qiuan; Peng, Changhui; Chen, Huai; Fang, Xiuqin; Liu, Jinxun; Jiang, Hong; Yang, Yanzheng; Yang, Gang

2015-01-01

Aim The fluctuations of atmospheric methane (CH4) that have occurred in recent decades are not fully understood, particularly with regard to the contribution from wetlands. The application of spatially explicit parameters has been suggested as an effective method for reducing uncertainties in bottom-up approaches to wetland CH4 emissions, but has not been included in recent studies. Our goal was to estimate spatio-temporal patterns of global wetland CH4 emissions using a process model and then to identify the contribution of wetland emissions to atmospheric CH4fluctuations. Location Global. Methods A process-based model integrated with full descriptions of methanogenesis (TRIPLEX-GHG) was used to simulate global wetland CH4emissions. Results Global annual wetland CH4 emissions ranged from 209 to 245 Tg CH4 year−1 between 1901 and 2012, with peaks occurring in 1991 and 2012. There is a decreasing trend between 1990 and 2010 with a rate of approximately 0.48 Tg CH4 year−1, which was largely caused by emissions from tropical wetlands showing a decreasing trend of 0.44 Tg CH4 year−1 since the 1970s. Emissions from tropical, temperate and high-latitude wetlands comprised 59, 26 and 15% of global emissions, respectively. Main conclusion Global wetland CH4 emissions, the interannual variability of which was primary controlled by tropical wetlands, partially drive the atmosphericCH4 burden. The stable to decreasing trend in wetland CH4 emissions, a result of a balance of emissions from tropical and extratropical wetlands, was a particular factor in slowing the atmospheric CH4 growth rate during the 1990s. The rapid decrease in tropical wetland CH4emissions that began in 2000 was supposed to offset the increase in anthropogenic emissions and resulted in a relatively stable level of atmospheric CH4 from 2000 to 2006. Increasing wetland CH4 emissions, particularly after 2010, should be an important contributor to the growth in atmospheric CH4 seen since 2007.

On Mars' Atmospheric Sputtering after Maven First two Years

NASA Astrophysics Data System (ADS)

Leblanc, F.; Modolo, R.; Curry, S.; Luhmann, J. G.; Lillis, R. J.; Chaufray, J. Y.; Hara, T.; McFadden, J. P.; Halekas, J. S.; Epavier, F.; Connerney, J. E. P.; Jakosky, B. M.

2017-12-01

Mars likely lost a significant part of its atmosphere to space during its history. The sputtering of the atmosphere by precipitating planetary picked up ions accelerated by the solar wind is one of the processes that could have significantly contributed to this atmospheric escape, in particular since the cessation of its global magnetic field, 4.0-4.1 Gyr ago. We here present a two year baseline analysis of MAVEN observations of the precipitating flux, in particular the dependence of the precipitating flux on solar zenith angle. We use this measurement to model the expected escape rate and exospheric structure induced by this precipitation.

Assessing Precipitation Isotope Variations during Atmospheric River Events to Reveal Dominant Atmospheric/Hydrologic Processes

NASA Astrophysics Data System (ADS)

McCabe-Glynn, S. E.; Johnson, K. R.; Yoshimura, K.; Buenning, N. H.; Welker, J. M.

2015-12-01

Extreme precipitation events across the Western US commonly associated with atmospheric rivers (ARs), whereby extensive fluxes of moisture are transported from the subtropics, can result in major damage and are projected by most climate models to increase in frequency and severity. However, they are difficult to project beyond ~ten days and the location of landfall and topographically induced precipitation is even more uncertain. Water isotopes, often used to reconstruct past rainfall variability, are useful natural tracers of atmospheric hydrologic processes. Because of the typical tropical and sub-tropical origins, ARs can carry unique water isotope (δ18O and δ2H, d-excess) signatures that can be utilized to provide source and process information that can lead to improving AR predictions. Recent analysis of the top 10 weekly precipitation total samples from Sequoia National Park, CA, of which 9 contained AR events, shows a high variability in the isotopic values. NOAA Hysplit back trajectory analyses reveals a variety of trajectories and varying latitudinal source regions contributed to moisture delivered to this site, which may explain part of the high variability (δ2H = -150.03 to -49.52 ‰, δ18O = -19.27 to -7.20 ‰, d-excess = 4.1 to 25.8). Here we examine the top precipitation totals occurring during AR events and the associated isotopic composition of precipitation samples from several sites across the Western US. We utilize IsoGSM, an isotope-enabled atmospheric general circulation model, to characterize the hydrologic processes and physical dynamics contributing to the observed isotopic variations. We investigate isotopic influences from moisture source location, AR speed, condensation height, and associated temperature. We explore the dominant controls on spatial and temporal variations of the isotopic composition of AR precipitation which highlights different physical processes for different AR events.

Disequilibrium in planetary atmospheres and the search for habitability

NASA Astrophysics Data System (ADS)

Simoncini, E.

It has long been observed that Earth's atmosphere is uniquely far from its thermochemical equilibrium state in terms of its chemical composition. Studying this state of disequilibrium is important for its potential role in the detection of life on other suitable planets \\citep{Lovelock_1965,Kleidon_2010,Simoncini_2015}. We developed a methodology to calculate the extent of atmospheric chemical disequilibrium\\citep{Simoncini_2015,Kondepudi_1996}. This tool allows us to understand, on a thermodynamic basis, how life affected - and still affects - geochemical processes on Earth, and if other planetary atmospheres are habitable or have a disequilibrium similar to the Earth's one. A new computational framework called KROME has been applied to atmospheric models in order to give a correct computation of reactions´ kinetics \\citep{Grassi_2015}. In this work we present a first computation of the extent of disequilibrium for the present Earth atmosphere, considering the specific contribution of the different atmospheric processes, such as thermochemical reactions, eddy diffusion, photochemistry, deposition, and the effect of the biosphere. We then assess the effect of life on atmospheric disequilibrium of the Earth and provide a useful discussion about how the study of atmospheric disequilibrium can help in finding habitable (exo)planets. We finally compare the chemical disequilibrium of Earth and Mars atmospheres, for present and early conditions.

A Synergistic Approach to Interpreting Planetary Atmospheres

NASA Astrophysics Data System (ADS)

Batalha, Natasha E.

We will soon have the technological capability to measure the atmospheric composition of temperate Earth-sized planets orbiting nearby stars. Interpreting these atmospheric signals poses a new challenge to planetary science. In contrast to jovian-like atmospheres, whose bulk compositions consist of hydrogen and helium, terrestrial planet atmospheres are likely comprised of high mean molecular weight secondary atmospheres, which have gone through a high degree of evolution. For example, present-day Mars has a frozen surface with a thin tenuous atmosphere, but 4 billion years ago it may have been warmed by a thick greenhouse atmosphere. Several processes contribute to a planet's atmospheric evolution: stellar evolution, geological processes, atmospheric escape, biology, etc. Each of these individual processes affects the planetary system as a whole and therefore they all must be considered in the modeling of terrestrial planets. In order to demonstrate the intricacies in modeling terrestrial planets, I use early Mars as a case study. I leverage a combination of one-dimensional climate, photochemical and energy balance models in order to create one self-consistent model that closely matches currently available climate data. One-dimensional models can address several processes: the influence of greenhouse gases on heating, the effect of the planet's geological processes (i.e. volcanoes and the carbonatesilicate cycle) on the atmosphere, the effect of rainfall on atmospheric composition and the stellar irradiance. After demonstrating the number of assumptions required to build a model, I look towards what exactly we can learn from remote observations of temperate Earths and Super Earths. However, unlike in-situ observations from our own solar system, remote sensing techniques need to be developed and understood in order to accurately characterize exo-atmospheres. I describe the models used to create synthetic transit transmission observations, which includes models of transit spectroscopy and instrumental noise. Using these, I lay the framework for an information content-based approach to optimize our observations and maximize the retrievable information from exoatmospheres. First I test the method on observing strategies of the well-studied, low-mean-molecular weight atmospheres of warm-Neptunes and hot Jupiters. Upon verifying the methodology, I finally address optimal observing strategies for temperate, high-mean-molecular weight atmospheres (Earths/super-Earths). iv.

Contribution of Arctic seabird-colony ammonia to atmospheric particles and cloud-albedo radiative effect

NASA Astrophysics Data System (ADS)

Croft, B.; Wentworth, G. R.; Martin, R. V.; Leaitch, W. R.; Murphy, J. G.; Murphy, B. N.; Kodros, J. K.; Abbatt, J. P. D.; Pierce, J. R.

2016-11-01

The Arctic region is vulnerable to climate change and able to affect global climate. The summertime Arctic atmosphere is pristine and strongly influenced by natural regional emissions, which have poorly understood climate impacts related to atmospheric particles and clouds. Here we show that ammonia from seabird-colony guano is a key factor contributing to bursts of newly formed particles, which are observed every summer in the near-surface atmosphere at Alert, Nunavut, Canada. Our chemical-transport model simulations indicate that the pan-Arctic seabird-influenced particles can grow by sulfuric acid and organic vapour condensation to diameters sufficiently large to promote pan-Arctic cloud-droplet formation in the clean Arctic summertime. We calculate that the resultant cooling tendencies could be large (about -0.5 W m-2 pan-Arctic-mean cooling), exceeding -1 W m-2 near the largest seabird colonies due to the effects of seabird-influenced particles on cloud albedo. These coupled ecological-chemical processes may be susceptible to Arctic warming and industrialization.

Can Arctic sea-ice melt be explained by atmospheric meridional transports? (Invited)

NASA Astrophysics Data System (ADS)

Tjernstrom, M. K.; Graversen, R. G.

2010-12-01

The Arctic summer sea ice is melting away at an alarming rate, and it is now expected that an principally sea-ice free Arctic summer will occur much earlier than projected by the IPCC AR4 models. At the same time Arctic near-surface temperatures are rising at a rate much faster than the global average. The processes responsible for these changes are debated and many claim that local feedbacks, such as the surface albedo feedback, are the main culprits while other argue that remote effects, such as atmospheric circulation changes on synoptic and hemispheric scales, are the most important. We will explore the effects of the meridional transport by synoptic and larger scale atmospheric circulation on recent changes, using reanalysis data. It will be illustarated how this transport can contribute significant amounts of sensible heat, but also of atmospheric moisture such that local cloud feedbacks as well as the direct greenhouse effect of the water vapor contributes significantly to the surface energy balance over the Arctic polar cap.

Contribution of Arctic seabird-colony ammonia to atmospheric particles and cloud-albedo radiative effect.

PubMed

Croft, B; Wentworth, G R; Martin, R V; Leaitch, W R; Murphy, J G; Murphy, B N; Kodros, J K; Abbatt, J P D; Pierce, J R

2016-11-15

The Arctic region is vulnerable to climate change and able to affect global climate. The summertime Arctic atmosphere is pristine and strongly influenced by natural regional emissions, which have poorly understood climate impacts related to atmospheric particles and clouds. Here we show that ammonia from seabird-colony guano is a key factor contributing to bursts of newly formed particles, which are observed every summer in the near-surface atmosphere at Alert, Nunavut, Canada. Our chemical-transport model simulations indicate that the pan-Arctic seabird-influenced particles can grow by sulfuric acid and organic vapour condensation to diameters sufficiently large to promote pan-Arctic cloud-droplet formation in the clean Arctic summertime. We calculate that the resultant cooling tendencies could be large (about -0.5 W m -2 pan-Arctic-mean cooling), exceeding -1 W m -2 near the largest seabird colonies due to the effects of seabird-influenced particles on cloud albedo. These coupled ecological-chemical processes may be susceptible to Arctic warming and industrialization.

Remote sensing of atmosphere and oceans; Proceedings of Symposium 1 and of the Topical Meeting of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

NASA Technical Reports Server (NTRS)

Raschke, E. (Editor); Ghazi, A. (Editor); Gower, J. F. R. (Editor); Mccormick, P. (Editor); Gruber, A. (Editor); Hasler, A. F. (Editor)

1989-01-01

Papers are presented on the contribution of space remote sensing observations to the World Climate Research Program and the Global Change Program, covering topics such as space observations for global environmental monitoring, experiments related to land surface fluxes, studies of atmospheric composition, structure, motions, and precipitation, and remote sensing for oceanography, observational studies of the atmosphere, clouds, and the earth radiation budget. Also, papers are given on results from space observations for meteorology, oceanography, and mesoscale atmospheric and ocean processes. The topics include vertical atmospheric soundings, surface water temperature determination, sea level variability, data on the prehurricane atmosphere, linear and circular mesoscale convective systems, Karman vortex clouds, and temporal patterns of phytoplankton abundance.

Atmospheric and Space Sciences: Ionospheres and Plasma Environments

NASA Astrophysics Data System (ADS)

Yiǧit, Erdal

2018-01-01

The SpringerBriefs on Atmospheric and Space Sciences in two volumes presents a concise and interdisciplinary introduction to the basic theory, observation & modeling of atmospheric and ionospheric coupling processes on Earth. The goal is to contribute toward bridging the gap between meteorology, aeronomy, and planetary science. In addition recent progress in several related research topics, such atmospheric wave coupling and variability, is discussed. Volume 1 will focus on the atmosphere, while Volume 2 will present the ionospheres and the plasma environments. Volume 2 is aimed primarily at (research) students and young researchers that would like to gain quick insight into the basics of space sciences and current research. In combination with the first volume, it also is a useful tool for professors who would like to develop a course in atmospheric and space physics.

Boron Dissolved and Particulate Atmospheric Inputs to a Forest Ecosystem (Northeastern France).

PubMed

Roux, Philippe; Turpault, Marie-Pierre; Kirchen, Gil; Redon, Paul-Olivier; Lemarchand, Damien

2017-12-19

Boron concentrations and isotopic compositions of atmospheric dust and dissolved depositions were monitored over a two-year period (2012-2013) in the forest ecosystem of Montiers (Northeastern France). This time series allows the determination of the boron atmospheric inputs to this forest ecosystem and contributes to refine our understanding of the sources and processes that control the boron atmospheric cycle. Mean annual dust and dissolved boron atmospheric depositions are comparable in size (13 g·ha -1 ·yr -1 and 16 g·ha -1 ·yr -1 , respectively), which however show significant intra- and interannual variations. Boron isotopes in dust differ from dissolved inputs, with an annual mean value of +1 ‰ and +18 ‰ for, respectively. The notable high boron contents (190-390 μg·g -1 ) of the dust samples are interpreted as resulting from localized spreading of boron-rich fertilizers, thus indicating a significant local impact of regional agricultural activities. Boron isotopes in dissolved depositions show a clear seasonal trend. The absence of correlation with marine cyclic solutes contradicts a control of atmospheric boron by dissolution of seasalts. Instead, the boron data from this study are consistent with a Rayleigh-like evolution of the atmospheric gaseous boron reservoir with possible but limited anthropogenic and/or biogenic contributions.

Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes.

PubMed

Gottschalk, Julia; Skinner, Luke C; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L; Waelbroeck, Claire

2016-05-17

Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and (14)C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.

Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

PubMed Central

Gottschalk, Julia; Skinner, Luke C.; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L.; Waelbroeck, Claire

2016-01-01

Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean–atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air–sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and 14C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes. PMID:27187527

Influence of atmospheric processes on the solubility and composition of iron in Saharan dust

DOE PAGES

Longo, Amelia F.; Feng, Yan; Lai, Barry; ...

2016-06-10

Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet-chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated the aerosol iron in Mediterranean samples. In Atlantic samples, iron(II and III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation statemore » became more reduced, and aerosol acidity increased. As a result, atmospheric processing including acidic reactions and photoreduction likely influence the form of iron minerals and oxidation state in Saharan dust aerosols and contribute to increases in aerosol-iron solubility.« less

Influence of Atmospheric Processes on the Solubility and Composition of Iron in Saharan Dust.

PubMed

Longo, Amelia F; Feng, Yan; Lai, Barry; Landing, William M; Shelley, Rachel U; Nenes, Athanasios; Mihalopoulos, Nikolaos; Violaki, Kalliopi; Ingall, Ellery D

2016-07-05

Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet-chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated the aerosol iron in Mediterranean samples. In Atlantic samples, iron(II and III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation state became more reduced, and aerosol acidity increased. Atmospheric processing including acidic reactions and photoreduction likely influence the form of iron minerals and oxidation state in Saharan dust aerosols and contribute to increases in aerosol-iron solubility.

Influence of Atmospheric Processes on the Solubility and Composition of Iron in Saharan Dust

NASA Astrophysics Data System (ADS)

Ingall, E. D.; Longo, A.; Feng, Y.; Lai, B.; Landing, W. M.; Shelley, R.; Nenes, A.; Mihalopoulos, N.; Violaki, K.

2016-12-01

Iron is a key micronutrient that is vital for all organisms. The supply of bioavailable, soluble iron controls primary productivity in approximately 30% of the world's oceans. The significant contribution of atmospheric aerosols to the bioavailable iron budget in vast ocean regions, underscores the need to understand the controls and transformations of aerosol iron solubility during atmospheric transport. The Sahara Desert contains the largest and most active sources of aerosol dust globally and can be a key source of nutrients to the Mediterranean Sea, much of the North Atlantic Ocean, and even as far as the Gulf of Mexico. Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated aerosol iron in Mediterranean samples. In Atlantic samples, iron(II & III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation state became more reduced, and aerosol acidity increased. Atmospheric processing, including acidic reactions and photo-reduction, likely influence the form of iron minerals and the oxidation state in Saharan dust aerosols and contribute to increases in aerosol iron solubility. Overall, these findings suggest that a combination of factors affects aerosol iron solubility during long-distance atmospheric transport and emphasize the need to consider reductive mechanisms as well as proton-induced solubilization of aerosol iron in modeling studies.

STUDYING ATMOSPHERE-DOMINATED HOT JUPITER KEPLER PHASE CURVES: EVIDENCE THAT INHOMOGENEOUS ATMOSPHERIC REFLECTION IS COMMON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shporer, Avi; Hu, Renyu

2015-10-15

We identify three Kepler transiting planets, Kepler-7b, Kepler-12b, and Kepler-41b, whose orbital phase-folded light curves are dominated by planetary atmospheric processes including thermal emission and reflected light, while the impact of non-atmospheric (i.e., gravitational) processes, including beaming (Doppler boosting) and tidal ellipsoidal distortion, is negligible. Therefore, those systems allow a direct view of their atmospheres without being hampered by the approximations used in the inclusion of both atmospheric and non-atmospheric processes when modeling the phase-curve shape. We present here the analysis of Kepler-12b and Kepler-41b atmosphere based on their Kepler phase curve, while the analysis of Kepler-7b was already presentedmore » elsewhere. The model we used efficiently computes reflection and thermal emission contributions to the phase curve, including inhomogeneous atmospheric reflection due to longitudinally varying cloud coverage. We confirm Kepler-12b and Kepler-41b show a westward phase shift between the brightest region on the planetary surface and the substellar point, similar to Kepler-7b. We find that reflective clouds located on the west side of the substellar point can explain the phase shift. The existence of inhomogeneous atmospheric reflection in all three of our targets, selected due to their atmosphere-dominated Kepler phase curve, suggests this phenomenon is common. Therefore, it is also likely to be present in planetary phase curves that do not allow a direct view of the planetary atmosphere as they contain additional orbital processes. We discuss the implications of a bright-spot shift on the analysis of phase curves where both atmospheric and gravitational processes appear, including the mass discrepancy seen in some cases between the companion’s mass derived from the beaming and ellipsoidal photometric amplitudes. Finally, we discuss the potential detection of non-transiting but otherwise similar planets, whose mass is too small to show a gravitational photometric signal, but their atmosphere is reflective enough to show detectable phase modulations.« less

Development status of the EarthCARE Mission and its atmospheric Lidar

NASA Astrophysics Data System (ADS)

Hélière, A.; Wallace, K.; Pereira Do Carmo, J.; Lefebvre, A.; Eisinger, M.; Wehr, T.

2016-09-01

The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop as part of ESA's Living Planet Programme, the third Earth Explorer Core Mission, EarthCARE, with the fundamental objective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earth's atmosphere. EarthCARE payload consists of two active and two passive instruments: an ATmospheric LIDar (ATLID), a Cloud Profiling Radar (CPR), a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer (BBR). The four instruments data are processed individually and in a synergetic manner to produce a large range of products, which include vertical profiles of aerosols, liquid water and ice, observations of cloud distribution and vertical motion within clouds, and will allow the retrieval of profiles of atmospheric radiative heating and cooling. Operating in the UV range at 355 nm, ATLID provides atmospheric echoes with a vertical resolution up to 100 m from ground to an altitude of 40 km. Thanks to a high spectral resolution filtering, the lidar is able to separate the relative contribution of aerosol (Mie) and molecular (Rayleigh) scattering, which gives access to aerosol optical depth. Co-polarised and cross-polarised components of the Mie scattering contribution are also separated and measured on dedicated channels. This paper gives an overview of the mission science objective, the satellite configuration with its four instruments and details more specifically the implementation and development status of the Atmospheric Lidar. Manufacturing status and first equipment qualification test results, in particular for what concerns the laser transmitter development are presented.

Methane emissions from oceans, coasts, and freshwater habitats: New perspectives and feedbacks on climate

USGS Publications Warehouse

Hamdan, Leila J.; Wickland, Kimberly P.

2016-01-01

Methane is a powerful greenhouse gas, and atmospheric concentrations have risen 2.5 times since the beginning of the Industrial age. While much of this increase is attributed to anthropogenic sources, natural sources, which contribute between 35% and 50% of global methane emissions, are thought to have a role in the atmospheric methane increase, in part due to human influences. Methane emissions from many natural sources are sensitive to climate, and positive feedbacks from climate change and cultural eutrophication may promote increased emissions to the atmosphere. These natural sources include aquatic environments such as wetlands, freshwater lakes, streams and rivers, and estuarine, coastal, and marine systems. Furthermore, there are significant marine sediment stores of methane in the form of clathrates that are vulnerable to mobilization and release to the atmosphere from climate feedbacks, and subsurface thermogenic gas which in exceptional cases may be released following accidents and disasters (North Sea blowout and Deepwater Horizon Spill respectively). Understanding of natural sources, key processes, and controls on emission is continually evolving as new measurement and modeling capabilities develop, and different sources and processes are revealed. This special issue of Limnology and Oceanography gathers together diverse studies on methane production, consumption, and emissions from freshwater, estuarine, and marine systems, and provides a broad view of the current science on methane dynamics of aquatic ecosystems. Here, we provide a general overview of aquatic methane sources, their contribution to the global methane budget, and key uncertainties. We then briefly summarize the contributions to and highlights of this special issue.

Team Learning: Collective Reflection Processes in Teacher Teams

ERIC Educational Resources Information Center

Ohlsson, Jon

2013-01-01

Purpose: The purpose of this paper is to contribute to further studies of theoretical and conceptual understanding of teachers' team learning processes, with a main focus on team work, team atmosphere, and collective reflections. Design/methodology/approach: The empirical study was designed as a multi-case study in a research and development…

Wave heating of the solar atmosphere

NASA Astrophysics Data System (ADS)

Arregui, Iñigo

2015-04-01

Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere.

Wave heating of the solar atmosphere

PubMed Central

Arregui, Iñigo

2015-01-01

Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere. PMID:25897091

An Overview of Modeling Middle Atmospheric Odd Nitrogen

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Kawa, S. Randolph; Einaudi, Franco (Technical Monitor)

2001-01-01

Odd nitrogen (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, and BrONO2) constituents are important components in the control of middle atmospheric ozone. Several processes lead to the production of odd nitrogen (NO(sub y)) in the middle atmosphere (stratosphere and mesosphere) including the oxidation of nitrous oxide (N2O), lightning, downflux from the thermosphere, and energetic charged particles (e.g., galactic cosmic rays, solar proton events, and energetic electron precipitation). The dominant production mechanism of NO(sub y) in the stratosphere is N2O oxidation, although other processes contribute. Mesospheric NO(sub y) is influenced by N2O oxidation, downflux from the thermosphere, and energetic charged particles. NO(sub y) is destroyed in the middle atmosphere primarily via two processes: 1) dissociation of NO to form N and O followed by N + NO yielding N2 + O to reform even nitrogen; and 2) transport to the troposphere where HNO3 can be rapidly scavenged in water droplets and rained out of the atmosphere. There are fairly significant differences among global models that predict NO(sub y). NO(sub y) has a fairly long lifetime in the stratosphere (months to years), thus disparate transport in the models probably contributes to many of these differences. Satellite and aircraft measurement provide modeling tests of the various components of NO(sub y). Although some recent reaction rate measurements have led to improvements in model/measurement agreement, significant differences do remain. This presentation will provide an overview of several proposed sources and sinks of NO(sub y) and their regions of importance. Multi-dimensional modeling results for NO(sub y) and its components with comparisons to observations will also be presented.

Variance and Predictability of Precipitation at Seasonal-to-Interannual Timescales

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Suarez, Max J.; Heiser, Mark

1999-01-01

A series of atmospheric general circulation model (AGCM) simulations, spanning a total of several thousand years, is used to assess the impact of land-surface and ocean boundary conditions on the seasonal-to-interannual variability and predictability of precipitation in a coupled modeling system. In the first half of the analysis, which focuses on precipitation variance, we show that the contributions of ocean, atmosphere, and land processes to this variance can be characterized, to first order, with a simple linear model. This allows a clean separation of the contributions, from which we find: (1) land and ocean processes have essentially different domains of influence, i.e., the amplification of precipitation variance by land-atmosphere feedback is most important outside of the regions (mainly in the tropics) that are most affected by sea surface temperatures; and (2) the strength of land-atmosphere feedback in a given region is largely controlled by the relative availability of energy and water there. In the second half of the analysis, the potential for seasonal-to-interannual predictability of precipitation is quantified under the assumption that all relevant surface boundary conditions (in the ocean and on land) are known perfectly into the future. We find that the chaotic nature of the atmospheric circulation imposes fundamental limits on predictability in many extratropical regions. Associated with this result is an indication that soil moisture initialization or assimilation in a seasonal-to-interannual forecasting system would be beneficial mainly in transition zones between dry and humid regions.

Snohomish RARE project update for Tulalip Tribes | Science ...

EPA Pesticide Factsheets

Rising atmospheric CO2 due to anthropogenic emissions alters local atmospheric gas exchange rates in estuaries, causing alterations of the seawater carbonate system and reductions in pH broadly described as coastal acidification. These changes in marine chemistry have been demonstrated to negatively affect a variety of coastal and estuarine organisms. The naturally dynamic carbonate chemistry of estuaries driven by biological activity, hydrodynamic processes, and intensive biogeochemical cycling has led to uncertainty regarding the role of rising atmospheric CO2 as a driver in these systems, and the suggestion that altered atmospheric exchange may be relatively unimportant to estuarine biogeochemistry. In this presentation, we illustrate how rising atmospheric CO2 from 1765 through 2100 interacts with the observed local carbonate chemistry dynamics of a seagrass bed, and calculated how pHT, pCO2, and Ωaragonite respond. This presentation is part of an informal meeting with the Tulalip Tribes of Tulalip, WA to update them on the progress of the ORD/Region 10 RARE project in the Snohomish estuary to study drivers of coastal acidification. Multiple processes, including primary production and respiration, river runoff, cultural eutrophication, oceanic upwelling, and atmospheric exchange contribute to the characteristically dynamic carbonate conditions in these habitats, with potential interactions amongst these processes leading to coastal acidification. As a

Terrestrial and Martian weathering signatures of xenon components in shergottite mineral separates

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Ocker, K. D.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.

2010-08-01

Xenon-isotopic ratios, step-heating release patterns, and gas concentrations of mineral separates from Martian shergottites Roberts Massif (RBT) 04262, Dar al Gani (DaG) 489, Shergotty, and Elephant Moraine (EET) 79001 lithology B are reported. Concentrations of Martian atmospheric xenon are similar in mineral separates from all meteorites, but more weathered samples contain more terrestrial atmospheric xenon. The distributions of xenon from the Martian and terrestrial atmospheres among minerals in any one sample are similar, suggesting similarities in the processes by which they were acquired. However, in opaque and maskelynite fractions, Martian atmospheric xenon is released at higher temperatures than terrestrial atmospheric xenon. It is suggested that both Martian and terrestrial atmospheric xenon were initially introduced by weathering (low temperature alteration processes). However, the Martian component was redistributed by shock, accounting for its current residence in more retentive sites. The presence or absence of detectable 129Xe from the Martian atmosphere in mafic minerals may correspond to the extent of crustal contamination of the rock's parent melt. Variable contents of excess 129Xe contrast with previously reported consistent concentrations of excess 40Ar, suggesting distinct sources contributed these gases to the parent magma.

Seasonal-to-Interannual Precipitation Variability and Predictability in a Coupled Land-Atmosphere System

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Suarez, M. J.; Heiser, M.

1998-01-01

In an earlier GCM study, we showed that interactive land surface processes generally contribute more to continental precipitation variance than do variable sea surface temperatures (SSTs). A new study extends this result through an analysis of 16-member ensembles of multi-decade GCM simulations. We can now show that in many regions, although land processes determine the amplitude of the interannual precipitation anomalies, variable SSTs nevertheless control their timing. The GCM data can be processed into indices that describe geographical variations in (1) the potential for seasonal-to-interannual prediction, and (2) the extent to which the predictability relies on the proper representation of land-atmosphere feedback.

The influence of leaf-atmosphere NH3(g ) exchange on the isotopic composition of nitrogen in plants and the atmosphere.

PubMed

Johnson, Jennifer E; Berry, Joseph A

2013-10-01

The distribution of nitrogen isotopes in the biosphere has the potential to offer insights into the past, present and future of the nitrogen cycle, but it is challenging to unravel the processes controlling patterns of mixing and fractionation. We present a mathematical model describing a previously overlooked process: nitrogen isotope fractionation during leaf-atmosphere NH3(g ) exchange. The model predicts that when leaf-atmosphere exchange of NH3(g ) occurs in a closed system, the atmospheric reservoir of NH3(g ) equilibrates at a concentration equal to the ammonia compensation point and an isotopic composition 8.1‰ lighter than nitrogen in protein. In an open system, when atmospheric concentrations of NH3(g ) fall below or rise above the compensation point, protein can be isotopically enriched by net efflux of NH3(g ) or depleted by net uptake. Comparison of model output with existing measurements in the literature suggests that this process contributes to variation in the isotopic composition of nitrogen in plants as well as NH3(g ) in the atmosphere, and should be considered in future analyses of nitrogen isotope circulation. The matrix-based modelling approach that is introduced may be useful for quantifying isotope dynamics in other complex systems that can be described by first-order kinetics. © 2013 John Wiley & Sons Ltd.

Space Vehicle Terrestrial Environment Design Requirements Guidelines

NASA Technical Reports Server (NTRS)

Johnson, Dale L.; Keller, Vernon W.; Vaughan, William W.

2006-01-01

The terrestrial environment is an important driver of space vehicle structural, control, and thermal system design. NASA is currently in the process of producing an update to an earlier Terrestrial Environment Guidelines for Aerospace Vehicle Design and Development Handbook. This paper addresses the contents of this updated handbook, with special emphasis on new material being included in the areas of atmospheric thermodynamic models, wind dynamics, atmospheric composition, atmospheric electricity, cloud phenomena, atmospheric extremes, and sea state. In addition, the respective engineering design elements are discussed relative to terrestrial environment inputs that require consideration. Specific lessons learned that have contributed to the advancements made in the application and awareness of terrestrial environment inputs for aerospace engineering applications are presented.

DSA process window expansion with novel DSA track hardware

NASA Astrophysics Data System (ADS)

Harumoto, Masahiko; Stokes, Harold; Tanaka, Yuji; Kaneyama, Koji; Pieczulewski, Chalres; Asai, Masaya; Argoud, Maxime; Servin, Isabelle; Chamiot-Maitral, Gaëlle; Claveau, Guillaume; Tiron, Raluca; Cayrefourcq, Ian

2017-03-01

PS-b-PMMA block copolymer is a well-known DSA material, and there are many DSA patterning methods that make effective the use of such 1st generation materials. Consequently, this variety of patterning methods opens a wide array of possibilities for DSA application[1-4]. Last year, during the inaugural International DSA Symposium, researchers and lithographers concurred on common key issues for DSA patterning methods such as: defect density, LWR, placement error, etc. Defect density was specifically expressed as the biggest obstacle for new processes. Coat-Develop track systems contribute to the DSA pattern fabrication and also influence the DSA pattern performances[4]. In this study, defectivity was investigated using an atmosphere-controlled chamber on the SOKUDO DUO track. As an initial step for expanding the DSA process window, fingerprint patterns were used for various atmospheric conditions during DSA self-assembly annealing. In this study, we will demonstrate an improved DSA process window, and then we will discuss the mechanism for this atmospheric effect.

Nonlinear dynamics of global atmospheric and earth system processes

NASA Technical Reports Server (NTRS)

Zhang, Taiping; Verbitsky, Mikhail; Saltzman, Barry; Mann, Michael E.; Park, Jeffrey; Lall, Upmanu

1995-01-01

During the grant period, the authors continued ongoing studies aimed at enhancing their understanding of the operation of the atmosphere as a complex nonlinear system interacting with the hydrosphere, biosphere, and cryosphere in response to external radiative forcing. Five papers were completed with support from the grant, representing contributions in three main areas of study: (1) theoretical studies of the interactive atmospheric response to changed biospheric boundary conditions measurable from satellites; (2) statistical-observational studies of global-scale temperature variability on interannual to century time scales; and (3) dynamics of long-term earth system changes associated with ice sheet surges.

Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2

PubMed Central

Keppel-Aleks, Gretchen; Wolf, Aaron S; Mu, Mingquan; Doney, Scott C; Morton, Douglas C; Kasibhatla, Prasad S; Miller, John B; Dlugokencky, Edward J; Randerson, James T

2014-01-01

The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO2) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO2 anomalies. Here we examined how the temporal evolution of CO2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO2 variability. We developed atmospheric CO2 patterns from each of these mechanisms during 1997–2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9 ± 0.4 Pg C yr−1 K−1. These results underscore the need for accurate attribution of the drivers of CO2 variability prior to using contemporary observations to constrain long-term ESM responses. PMID:26074665

Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2.

PubMed

Keppel-Aleks, Gretchen; Wolf, Aaron S; Mu, Mingquan; Doney, Scott C; Morton, Douglas C; Kasibhatla, Prasad S; Miller, John B; Dlugokencky, Edward J; Randerson, James T

2014-11-01

The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO 2 ) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO 2 anomalies. Here we examined how the temporal evolution of CO 2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO 2 variability. We developed atmospheric CO 2 patterns from each of these mechanisms during 1997-2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO 2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO 2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO 2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9 ± 0.4 Pg C yr -1  K -1 . These results underscore the need for accurate attribution of the drivers of CO 2 variability prior to using contemporary observations to constrain long-term ESM responses.

Detecting anthropogenic footprints in sea level rise

NASA Astrophysics Data System (ADS)

Dangendorf, Sönke; Marcos, Marta; Müller, Alfred; Zorita, Eduardo; Riva, Riccardo; Berk, Kevin; Jensen, Jürgen

2015-07-01

While there is scientific consensus that global and local mean sea level (GMSL and LMSL) has risen since the late nineteenth century, the relative contribution of natural and anthropogenic forcing remains unclear. Here we provide a probabilistic upper range of long-term persistent natural GMSL/LMSL variability (P=0.99), which in turn, determines the minimum/maximum anthropogenic contribution since 1900. To account for different spectral characteristics of various contributing processes, we separate LMSL into two components: a slowly varying volumetric component and a more rapidly changing atmospheric component. We find that the persistence of slow natural volumetric changes is underestimated in records where transient atmospheric processes dominate the spectrum. This leads to a local underestimation of possible natural trends of up to ~1 mm per year erroneously enhancing the significance of anthropogenic footprints. The GMSL, however, remains unaffected by such biases. On the basis of a model assessment of the separate components, we conclude that it is virtually certain (P=0.99) that at least 45% of the observed increase in GMSL is of anthropogenic origin.

Evaluating experimental molecular physics studies of radiation damage in DNA*

NASA Astrophysics Data System (ADS)

Śmiałek, Małgorzata A.

2016-11-01

The field of Atomic and Molecular Physics (AMP) is a mature field exploring the spectroscopy, excitation, ionisation of atoms and molecules in all three phases. Understanding of the spectroscopy and collisional dynamics of AMP has been fundamental to the development and application of quantum mechanics and is applied across a broad range of disparate disciplines including atmospheric sciences, astrochemistry, combustion and environmental science, and in central to core technologies such as semiconductor fabrications, nanotechnology and plasma processing. In recent years the molecular physics also started significantly contributing to the area of the radiation damage at molecular level and thus cancer therapy improvement through both experimental and theoretical advances, developing new damage measurement and analysis techniques. It is therefore worth to summarise and highlight the most prominent findings from the AMP community that contribute towards better understanding of the fundamental processes in biologically-relevant systems as well as to comment on the experimental challenges that were met for more complex investigation targets. Contribution to the Topical Issue "Low-Energy Interactions related to Atmospheric and Extreme Conditions", edited by S. Ptasinska, M. Smialek-Telega, A. Milosavljevic, B. Sivaraman.

Non-LTE calculation of HCL earthlimb emission and implication for detection of HCl in the atmosphere

NASA Technical Reports Server (NTRS)

Kumer, J. B.; James, T. C.

1982-01-01

Calculation results are presented for the contribution of the non-Local Thermodynamic Equilibrium process of resonant scattering of sunlight in the 1-0 band of HCl to the earthlimb radiance, for the case of tangent altitudes from 20 to 90 km. It is established that the mechanism in question is a significant contributor to radiance at altitudes as low as 20 km, and that it becomes greater than the Local Thermodynamic Equilibrium contribution above 40 km. Attention is given to the prospects for detection of HCl at altitudes approaching 80 km, by means of the Cryogenic Limb Array Etalon Spectrometer scheduled for deployment by the NASA Upper Atmospheric Research Satellite.

Cloud processing of organic compounds: Secondary organic aerosol and nitrosamine formation

NASA Astrophysics Data System (ADS)

Hutchings, James W., III

Cloud processing of atmospheric organic compounds has been investigated through field studies, laboratory experiments, and numerical modeling. Observational cloud chemistry studies were performed in northern Arizona and fog studies in central Pennsylvania. At both locations, the cloud and fogs showed low acidity due to neutralization by soil dust components (Arizona) and ammonia (Pennsylvania). The field observations showed substantial concentrations (20-5500 ng•L -1) of volatile organic compounds (VOC) in the cloud droplets. The potential generation of secondary organic aerosol mass through the processing of these anthropogenic VOCs was investigated through laboratory and modeling studies. Under simulated atmospheric conditions, in idealized solutions, benzene, toluene, ethylbenzene, and xylene (BTEX) degraded quickly in the aqueous phase with half lives of approximately three hours. The degradation process yielded less volatile products which would contribute to new aerosol mass upon cloud evaporation. However, when realistic cloud solutions containing natural organic matter were used in the experiments, the reaction kinetics decreased with increasing organic carbon content, resulting in half lives of approximately 7 hours. The secondary organic aerosol (SUA) mass formation potential of cloud processing of BTEX was evaluated. SOA mass formation by cloud processing of BTEX, while strongly dependent on the atmospheric conditions, could contribute up to 9% of the ambient atmospheric aerosol mass, although typically ˜1% appears realistic. Field observations also showed the occurrence of N-nitrosodimethylamine (NDMA), a potent carcinogen, in fogs and clouds (100-340 ng•L -1). Laboratory studies were conducted to investigate the formation of NDMA from nitrous acid and dimethylamine in the homogeneous aqueous phase within cloud droplets. While NDMA was produced in the cloud droplets, the low yields (<1%) observed could not explain observational concentrations. Therefore heterogeneous or gaseous formation of NDMA with partitioning to droplet must be the source of aqueous NDMA. Box-model calculations tended to demonstrate a predominance of a gas phase formation mechanism followed by partitioning into the cloud droplets. The calculations were consistent with field measurements of gaseous and aqueous NDMA concentrations. Measurements and model calculations showed that while NDMA is eventually photolyzed, it might persist in the atmosphere for hours.

NIST Standards for Measurement, Instrument Calibration, and Quantification of Gaseous Atmospheric Compounds.

PubMed

Rhoderick, George C; Kelley, Michael E; Miller, Walter R; Norris, James E; Carney, Jennifer; Gameson, Lyn; Cecelski, Christina E; Harris, Kimberly J; Goodman, Cassie A; Srivastava, Abneesh; Hodges, Joseph T

2018-04-03

There are many gas phase compounds present in the atmosphere that affect and influence the earth's climate. These compounds absorb and emit radiation, a process which is the fundamental cause of the greenhouse effect. The major greenhouse gases in the earth's atmosphere are carbon dioxide, methane, nitrous oxide, and ozone. Some halocarbons are also strong greenhouse gases and are linked to stratospheric ozone depletion. Hydrocarbons and monoterpenes are precursors and contributors to atmospheric photochemical processes, which lead to the formation of particulates and secondary photo-oxidants such as ozone, leading to photochemical smog. Reactive gases such as nitric oxide and sulfur dioxide are also compounds found in the atmosphere and generally lead to the formation of other oxides. These compounds can be oxidized in the air to acidic and corrosive gases and contribute to photochemical smog. Measurements of these compounds in the atmosphere have been ongoing for decades to track growth rates and assist in curbing emissions of these compounds into the atmosphere. To accurately establish mole fraction trends and assess the role of these gas phase compounds in atmospheric chemistry, it is essential to have good calibration standards. The National Institute of Standards and Technology has been developing standards of many of these compounds for over 40 years. This paper discusses the development of these standards.

Atmospheric processes over complex terrain

NASA Astrophysics Data System (ADS)

Banta, Robert M.; Berri, G.; Blumen, William; Carruthers, David J.; Dalu, G. A.; Durran, Dale R.; Egger, Joseph; Garratt, J. R.; Hanna, Steven R.; Hunt, J. C. R.

1990-06-01

A workshop on atmospheric processes over complex terrain, sponsored by the American Meteorological Society, was convened in Park City, Utah from 24 vto 28 October 1988. The overall objective of the workshop was one of interaction and synthesis--interaction among atmospheric scientists carrying out research on a variety of orographic flow problems, and a synthesis of their results and points of view into an assessment of the current status of topical research problems. The final day of the workshop was devoted to an open discussion on the research directions that could be anticipated in the next decade because of new and planned instrumentation and observational networks, the recent emphasis on development of mesoscale numerical models, and continual theoretical investigations of thermally forced flows, orographic waves, and stratified turbulence. This monograph represents an outgrowth of the Park City Workshop. The authors have contributed chapters based on their lecture material. Workshop discussions indicated interest in both the remote sensing and predictability of orographic flows. These chapters were solicited following the workshop in order to provide a more balanced view of current progress and future directions in research on atmospheric processes over complex terrain.

Urban aerosol particles of Santiago, Chile:. organic content and molecular characterization

NASA Astrophysics Data System (ADS)

Didyk, Borys M.; Simoneit, Bernd R. T.; Alvaro Pezoa, L.; Luis Riveros, M.; Anselmo Flores, A.

Santiago, Chile has developed a significant problem of atmospheric contamination with high levels of total suspended aerosol particles consisting of a high PM-10 fraction. This is associated with a growing economy, rapid urban expansion, increasing rate of motorization and expanding industrial activity. The organic contribution to atmospheric suspended particles (PM-10) in Santiago has been quantitated, characterized and related to its input sources in this report. The average organic content of 38% is significantly lower from pre-regulatory levels of 71% and in the range reported for other urban centers. Molecular markers indicate that a predominant proportion of the organic compounds associated with the particluate matter are derived from uncombusted diesel, uncombusted lubricating oil and other petrochemical fuel use. A significant organic contribution from natural plant wax hydrocarbons is also detected, suggesting biomass fuel use, open burning of vegetation in incidental fires or agricultural practices and resuspension of weathered vegetation debris. Aromatic hydrocarbon fractions indicate the presence of pyrogenic PAH formed by high-temperature combustion processes of petrochemical fuels with a significant contribution of retene indicative of conifer wood combustion. Maturity indicators, based on methylphenanthrene indexes, also indicate the simultaneous concurrence of high- and low-temperature combustion processes and confirm a significant contribution of non-petrochemical-sourced organic compounds to the atmospheric aerosols. Benzopyrene ratios indicate that Santiago aerosols are freshly generated and do not have an extensive solar exposure. The present study provides a reference baseline for the organic components relating to air quality in Santiago, and will permit the assessment of the environmental effectiveness of corrective measures related to energy usage and transport administration.

Atmospheric Correction for Satellite Ocean Color Radiometry

NASA Technical Reports Server (NTRS)

Mobley, Curtis D.; Werdell, Jeremy; Franz, Bryan; Ahmad, Ziauddin; Bailey, Sean

2016-01-01

This tutorial is an introduction to atmospheric correction in general and also documentation of the atmospheric correction algorithms currently implemented by the NASA Ocean Biology Processing Group (OBPG) for processing ocean color data from satellite-borne sensors such as MODIS and VIIRS. The intended audience is graduate students or others who are encountering this topic for the first time. The tutorial is in two parts. Part I discusses the generic atmospheric correction problem. The magnitude and nature of the problem are first illustrated with numerical results generated by a coupled ocean-atmosphere radiative transfer model. That code allow the various contributions (Rayleigh and aerosol path radiance, surface reflectance, water-leaving radiance, etc.) to the topof- the-atmosphere (TOA) radiance to be separated out. Particular attention is then paid to the definition, calculation, and interpretation of the so-called "exact normalized water-leaving radiance" and its equivalent reflectance. Part I ends with chapters on the calculation of direct and diffuse atmospheric transmittances, and on how vicarious calibration is performed. Part II then describes one by one the particular algorithms currently used by the OBPG to effect the various steps of the atmospheric correction process, viz. the corrections for absorption and scattering by gases and aerosols, Sun and sky reflectance by the sea surface and whitecaps, and finally corrections for sensor out-of-band response and polarization effects. One goal of the tutorial-guided by teaching needs- is to distill the results of dozens of papers published over several decades of research in atmospheric correction for ocean color remote sensing.

Seasonality of Forcing by Carbonaceous Aerosols

NASA Astrophysics Data System (ADS)

Habib, G.; Bond, T.; Rasch, P. J.; Coleman, D.

2006-12-01

Aerosols can influence the energy balance of Earth-Atmosphere system with profound effect on regional climate. Atmospheric processes, such as convection, scavenging, wet and dry deposition, govern the lifetime and location of aerosol; emissions affect its quantity and location. Both affect climate forcing. Here we investigate the effect of seasonality in emissions and atmospheric processes on radiative forcing by carbonaceous aerosols, focusing on aerosol from fossil fuel and biofuel. Because aerosol lifetime is seasonal, ignoring the seasonality of sources such as residential biofuel may introduce a bias in aerosol burden and therefore in predicted climate forcing. We present a global emission inventory of carbonaceous aerosols with seasonality, and simulate atmospheric concentrations using the Community Atmosphere Model (CAM). We discuss where and when the seasonality of emissions and atmospheric processes has strong effects on atmospheric burden, lifetime, climate forcing and aerosol optical depth (AOD). Previous work has shown that aerosol forcing is higher in summer than in winter, and has identified the importance of aerosol above cloud in determining black carbon forcing. We show that predicted cloud height is a very important factor in determining normalized radiative forcing (forcing per mass), especially in summer. This can affect the average summer radiative forcing by nearly 50%. Removal by cloud droplets is the dominant atmospheric cleansing mechanism for carbonaceous aerosols. We demonstrate the modeled seasonality of removal processes and compare the importance of scavenging by warm and cold clouds. Both types of clouds contribute significantly to aerosol removal. We estimate uncertainty in direct radiative forcing due to scavenging by tagging the aerosol which has experienced cloud interactions. Finally, seasonal variations offer an opportunity to assess modeled processes when a single process dominates variability. We identify regions where aerosol burden is most sensitive to convection and scavenging in warm and cold clouds, and compare seasonally modeled AOD with that retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS).

The U.S. Climate Change Science Program. Vision for the Program and Highlights of the Scientific Strategic Plan

DTIC Science & Technology

2003-07-01

CH4, N2O, O3, etc. Aerosols Clouds ATMOSPHERIC COMPOSITION WATER CYCLE LAND-USE/ LAND-COVER CHANGE HUMAN CONTRIBUTIONS AND RESPONSES CARBON...Oceanographic Institution. Climate Variability and Change ATMOSPHERIC COMPOSITION CLIMATE VARIABILITY AND CHANGE GLOBAL WATER CYCLE LAND-USE/LAND-COVER CHANGE...their access to and use of water. CCSP-supported research on the global water cycle focuses on how natural processes and human activities influence the

Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

USGS Publications Warehouse

Molins, S.; Mayer, K.U.

2007-01-01

The two‐way coupling that exists between biogeochemical reactions and vadose zone transport processes, in particular gas phase transport, determines the composition of soil gas. To explore these feedback processes quantitatively, multicomponent gas diffusion and advection are implemented into an existing reactive transport model that includes a full suite of geochemical reactions. Multicomponent gas diffusion is described on the basis of the dusty gas model, which accounts for all relevant gas diffusion mechanisms. The simulation of gas attenuation in partially saturated landfill soil covers, methane production, and oxidation in aquifers contaminated by organic compounds (e.g., an oil spill site) and pyrite oxidation in mine tailings demonstrate that both diffusive and advective gas transport can be affected by geochemical reactions. Methane oxidation in landfill covers reduces the existing upward pressure gradient, thereby decreasing the contribution of advective methane emissions to the atmosphere and enhancing the net flux of atmospheric oxygen into the soil column. At an oil spill site, methane oxidation causes a reversal in the direction of gas advection, which results in advective transport toward the zone of oxidation both from the ground surface and the deeper zone of methane production. Both diffusion and advection contribute to supply atmospheric oxygen into the subsurface, and methane emissions to the atmosphere are averted. During pyrite oxidation in mine tailings, pressure reduction in the reaction zone drives advective gas flow into the sediment column, enhancing the oxidation process. In carbonate‐rich mine tailings, calcite dissolution releases carbon dioxide, which partly offsets the pressure reduction caused by O2 consumption.

The MAGO experiment for dust environment monitoring on the Martian surface

NASA Astrophysics Data System (ADS)

Palumbo, P.; Battaglia, R.; Brucato, J. R.; Colangeli, L.; della Corte, V.; Esposito, F.; Ferrini, G.; Mazzotta Epifani, E.; Mennella, V.; Palomba, E.; Panizza, A.; Rotundi, A.

2004-01-01

Among the main directions identified for future Martian exploration, the study of the properties of dust dispersed in the atmosphere, its cycle and the impact on climate are considered of primary relevance. Dust storms, dust devils and the dust ``cycle'' have been identified and studied by past remote and in situ experiments, but little quantitative information is available on these processes, so far. The airborne dust contributes to the determination of the dynamic and thermodynamic evolution of the atmosphere, including the large-scale circulation processes and its impact on the climate of Mars. Moreover, aeolian erosion, redistribution of dust on the surface and weathering processes are mostly known only qualitatively. In order to improve our knowledge of the airborne dust evolution and other atmospheric processes, it is mandatory to measure the amount, mass-size distribution and dynamical properties of solid particles in the Martian atmosphere as a function of time. In this context, there is clearly a need for the implementation of experiments dedicated to study directly atmospheric dust. The Martian atmospheric grain observer (MAGO) experiment is aimed at providing direct quantitative measurements of mass and size distributions of dust particles, a goal that has never been fully achieved so far. The instrument design combines three types of sensors to monitor in situ the dust mass flux (micro balance system, MBS) and single grain properties (grain detection system, GDS+impact sensor, IS). Technical solutions and science capabilities are discussed in this paper.

A DATA SYSTEM FOR INTEGRATING DATA FROM LANDSCAPES, STREAMS AND ESTUARIES

EPA Science Inventory

Estuaries are natural integrators of substances and processes that occur internally and externally (watersheds, ocean, atmosphere). Watershed activities that contribute fresh water, nutrients, contaminants, and suspended solids have a strong effect on the health of estuaries. Res...

SEMINAR PUBLICATION: ORGANIC AIR EMISSIONS FROM WASTE MANAGEMENT FACILITIES

EPA Science Inventory

The organic chemicals contained in wastes processed during waste management operations can volatilize into the atmosphere and cause toxic or carcinogenic effects or contribute to ozone formation. Because air emissions from waste management operations pose a threat to human health...

Contribution of Arctic seabird-colony ammonia to atmospheric particles and cloud-albedo radiative effect

PubMed Central

Croft, B.; Wentworth, G. R.; Martin, R. V.; Leaitch, W. R.; Murphy, J. G.; Murphy, B. N.; Kodros, J. K.; Abbatt, J. P. D.; Pierce, J. R.

2016-01-01

The Arctic region is vulnerable to climate change and able to affect global climate. The summertime Arctic atmosphere is pristine and strongly influenced by natural regional emissions, which have poorly understood climate impacts related to atmospheric particles and clouds. Here we show that ammonia from seabird-colony guano is a key factor contributing to bursts of newly formed particles, which are observed every summer in the near-surface atmosphere at Alert, Nunavut, Canada. Our chemical-transport model simulations indicate that the pan-Arctic seabird-influenced particles can grow by sulfuric acid and organic vapour condensation to diameters sufficiently large to promote pan-Arctic cloud-droplet formation in the clean Arctic summertime. We calculate that the resultant cooling tendencies could be large (about −0.5 W m−2 pan-Arctic-mean cooling), exceeding −1 W m−2 near the largest seabird colonies due to the effects of seabird-influenced particles on cloud albedo. These coupled ecological–chemical processes may be susceptible to Arctic warming and industrialization. PMID:27845764

Contributions of Organic Sources to Atmospheric Aerosol Particle Concentrations and Growth

NASA Astrophysics Data System (ADS)

Russell, L. M.

2017-12-01

Organic molecules are important contributors to aerosol particle mass and number concentrations through primary emissions as well as secondary growth in the atmosphere. New techniques for measuring organic aerosol components in atmospheric particles have improved measurements of this contribution in the last 20 years, including Scanning Transmission X-ray Microscopy Near Edge X-ray Absorption Fine Structure (STXM-NEXAFS), Fourier Transform Infrared spectroscopy (FTIR), and High-Resolution Aerosol Mass Spectrometry (AMS). STXM-NEXAFS individual aerosol particle composition illustrated the variety of morphology of organic components in marine aerosols, the inherent relationships between organic composition and shape, and the links between atmospheric aerosol composition and particles produced in smog chambers. This type of single particle microscopy has also added to size distribution measurements by providing evidence of how surface-controlled and bulk-controlled processes contribute to the growth of particles in the atmosphere. FTIR analysis of organic functional groups are sufficient to distinguish combustion, marine, and terrestrial organic particle sources and to show that each of those types of sources has a surprisingly similar organic functional group composition over four different oceans and four different continents. Augmenting the limited sampling of these off-line techniques with side-by-side inter-comparisons to online AMS provides complementary composition information and consistent quantitative attribution to sources (despite some clear method differences). Single-particle AMS techniques using light scattering and event trigger modes have now also characterized the types of particles found in urban, marine, and ship emission aerosols. Most recently, by combining with off-line techniques, single particle composition measurements have separated and quantified the contributions of organic, sulfate and salt components from ocean biogenic and sea spray emissions to particles, addressing the persistent question of the sources of cloud condensation nuclei in clean marine conditions.

Mercury mass flow in iron and steel production process and its implications for mercury emission control.

PubMed

Wang, Fengyang; Wang, Shuxiao; Zhang, Lei; Yang, Hai; Gao, Wei; Wu, Qingru; Hao, Jiming

2016-05-01

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%-49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%-36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039-0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%-73% of total mercury emissions to air. Copyright © 2016. Published by Elsevier B.V.

Observations of seasonal variations in atmospheric greenhouse trapping and its enhancement at high sea surface temperature

NASA Technical Reports Server (NTRS)

Hallberg, Robert; Inamdar, Anand K.

1993-01-01

Greenhouse trapping is examined theoretically using a version of the radiative transfer equations that demonstrates how atmospheric greenhouse trapping can vary. Satellite observations of atmospheric greenhouse trapping are examined for four months representing the various seasons. The cause of the super greenhouse effect at the highest SSTs is examined, and four processes are found to contribute. The middle and upper troposphere must be particularly moist and the temperature lapse rate must be increasingly unstable over the warmest regions to explain the observed distribution of atmospheric greenhouse trapping. Since the highest SSTs are generally associated with deep convection, this suggests that deep convection acts to moisten the middle and upper troposphere in regions of the highest SSTs relative to other regions. The tropical atmospheric circulation acts to both increase the temperature lapse rate and greatly increase the atmospheric water vapor concentration with spatially increasing SST.

Conditions leading to the unprecedented low Antarctic sea ice extent during the 2016 austral spring season

NASA Astrophysics Data System (ADS)

Stuecker, Malte F.; Bitz, Cecilia M.; Armour, Kyle C.

2017-09-01

The 2016 austral spring was characterized by the lowest Southern Hemisphere (SH) sea ice extent seen in the satellite record (1979 to present) and coincided with anomalously warm surface waters surrounding most of Antarctica. We show that two distinct processes contributed to this event: First, the extreme El Niño event peaking in December-February 2015/2016 contributed to pronounced extratropical SH sea surface temperature and sea ice extent anomalies in the eastern Ross, Amundsen, and Bellingshausen Seas that persisted in part until the following 2016 austral spring. Second, internal unforced atmospheric variability of the Southern Annular Mode promoted the exceptional low sea ice extent in November-December 2016. These results suggest that a combination of tropically forced and internal SH atmospheric variability contributed to the unprecedented sea ice decline during the 2016 austral spring, on top of a background of slow changes expected from greenhouse gas and ozone forcing.

Nonlinear dynamics of global atmospheric and Earth system processes

NASA Technical Reports Server (NTRS)

Saltzman, Barry

1993-01-01

During the past eight years, we have been engaged in a NASA-supported program of research aimed at establishing the connection between satellite signatures of the earth's environmental state and the nonlinear dynamics of the global weather and climate system. Thirty-five publications and four theses have resulted from this work, which included contributions in five main areas of study: (1) cloud and latent heat processes in finite-amplitude baroclinic waves; (2) application of satellite radiation data in global weather analysis; (3) studies of planetary waves and low-frequency weather variability; (4) GCM studies of the atmospheric response to variable boundary conditions measurable from satellites; and (5) dynamics of long-term earth system changes. Significant accomplishments from the three main lines of investigation pursued during the past year are presented and include the following: (1) planetary atmospheric waves and low frequency variability; (2) GCM studies of the atmospheric response to changed boundary conditions; and (3) dynamics of long-term changes in the global earth system.

Aura Satellite Mission: Oxford/RAL Spring School in Quantitative Earth Observation

NASA Technical Reports Server (NTRS)

Douglass, Anne

2005-01-01

The four instruments on Aura are providing new and exciting measurements of stratospheric and tropospheric ozone, species that contribute to ozone production and loss, and long-lived gases such as nitrous oxide and methane that provide information about atmospheric transport. These discussions of atmospheric chemistry will start with the basic principles of ozone production and loss. Aura data will be used where possible to illustrate the pertinent atmospheric processes. Three-dimensional model simulations will be used both to illustrate present capabilities in constituent modeling and to demonstrate how observations are used to evaluate and improve models and our ability to predict future ozone evolution.

New insights into the nation's carbon storage potential

USGS Publications Warehouse

Warwick, Peter D.; Zhu, Zhi-Liang

2012-01-01

Carbon sequestration is a method of securing carbon dioxide (CO2) to prevent its release into the atmosphere, where it contributes to global warming as a greenhouse gas. Geologic storage of CO2 in porous and permeable rocks involves injecting high-pressure CO2 into a subsurface rock unit that has available pore space. Biologic carbon sequestration refers to both natural and anthropogenic processes by which CO2 is removed from the atmosphere and stored as carbon in vegetation, soils, and sediments.

An investigation of the role of current and future remote sensing data systems in numerical meteorology

NASA Technical Reports Server (NTRS)

Diak, George R.; Smith, William L.

1992-01-01

A flexible system for performing observing system simulation experiments which made contributions to meteorology across all elements of the observing system simulation experiment (OSSE) components was developed. Future work will seek better understanding of the links between satellite-measured radiation and radiative transfer in the clear, cloudy and precipitating atmosphere and investigate how that understanding might be applied to improve the depiction of the initial state and the treatment of physical processes in forecast models of the atmosphere.

Martian Surface and Atmosphere Workshop

NASA Astrophysics Data System (ADS)

Schuraytz, Benjamin C.

The NASA-sponsored Martian Surface and Atmosphere Through Time Study Project convened its first major meeting at the University of Colorado in Boulder, September 23-25, 1991. The workshop, co-sponsored by the Lunar and Planetary Institute (LPI) and the Laboratory for Atmospheric and Space Physics at the University of Colorado, brought together an international group of 125 scientists to discuss a variety of issues relevant to the goals of the MSATT Program. The workshop program committee included co-convenors Robert Haberle, MSATT Steering Committee Chairman NASA Ames Research Center) and Bruce Jakosky (University of Colorado), and committee members Amos Banin (NASA Ames Research Center and Hebrew University), Benjamin Schuraytz (LPI), and Kenneth Tanaka (U.S. Geological Survey, Flagstaff, Ariz.).The purpose of the workshop was to begin exploring and defining the relationships between different aspects of Mars science—the evolution of the surface, the atmosphere, upper atmosphere, volatiles, and climate. Specific topics addressed in the 88 contributed abstracts included the current nature of the surface with respect to physical properties and photometric observations and interpretations; the history of geological processes, comprising water and ice-related geomorphology, impact cratering, and volcanism; and the geochemistry and mineralogy of the surface with emphasis on compositional and spectroscopic studies and weathering processes. Also addressed were the present atmosphere, focusing on structure and dynamics, volatile and dust distribution, and the upper atmosphere; long-term volatile evolution based on volatiles in SNC meteorites (certain meteorites thought to have come from Mars) and atmospheric evolution processes; climate history and volatile cycles in relation to early climate and the polar caps, ground ice, and regolith; and future mission concepts.

Exploring the Contribution of Primary Marine Organic Matter to the Arctic Boundary Layer

NASA Astrophysics Data System (ADS)

Collins, D. B.; Chang, R. Y. W.; Boyer, M.; Abbatt, J.

2016-12-01

The ocean is a significant source of aerosol to the atmosphere, and contributes significantly to the aerosol population especially in remote locations. Both primary and secondary processes connect the ocean to ambient aerosol loadings, but the extent to which the ocean is a source of organic material to the atmosphere is a current topic of scientific debate. The contribution of primary marine aerosol to atmospheric organic matter may have an influence on the water uptake properties and chemical reactivity of primary marine aerosol particles, influencing their climate-relevant properties. In this study, we characterize the contribution of primary marine aerosol to the arctic marine boundary layer using coincident quantitative measurements of freshly-produced sea spray aerosol and ambient marine aerosol to the arctic boundary layer during an expedition aboard the CCGS Amundsen. Sea spray production experiments were conducted during the cruise using a tank fitted with a plunging waterfall apparatus, a technique which has been recently shown to closely mimic the aerosol production behavior of controlled breaking waves. Comparison of the chemical composition of sea spray particles generated from water samples in various locations throughout the Canadian Archipelago will be presented. A tracer analysis of specific compounds known to be important contributors to primary marine organic material are tracked using GC/MS, along with those known to be tracers of biological aerosol and other organic matter sources. Size-segregated trends in tracer concentrations and ratios with inorganic components will be discussed in the context of understanding the contribution of primary organics to the Arctic atmosphere and in comparison with other sources of organic material observed during the ship-board campaign.

Examinations on Laser Remote Welding of Ultra-thin Metal Foils Under Vacuum Conditions

NASA Astrophysics Data System (ADS)

Petrich, Martin; Stambke, Martin; Bergmann, Jean Pierre

Metal foils are commonly used for catalytic converters, vacuum insulations, in medical and electrical industry as well as for sensor applications and packaging. The investigations in this paper determine the influence of reduced atmospheric pressure during the welding process with a highly brilliant 400 W single-mode fiber laser combined with a 2D-scanning system. The laser beam is transmitted through a highly transparent glass into a vacuum chamber, where AISI 304 stainless steel foils with a thickness of 25 μm, 50 μm and 100 μm are positioned. The effects of reduced atmospheric pressure on the plasma formation are investigated by means of high-speed videography. Furthermore, the geometry of the weld seam is compared to atmospheric conditions as well as means of the process stability and the process efficiency. The welds were also evaluated by means of metallography. The research is a contribution for extending the range of micro welding applications and shows new aspects for future developments.

Atmosphere Processing Module Automation and Catalyst Durability Analysis for Mars ISRU Pathfinder

NASA Technical Reports Server (NTRS)

Petersen, Elspeth M.

2016-01-01

The Mars In-Situ Resource Utilization Pathfinder was designed to create fuel using components found in the planet’s atmosphere and regolith for an ascension vehicle to return a potential sample return or crew return vehicle from Mars. The Atmosphere Processing Module (APM), a subunit of the pathfinder, uses cryocoolers to isolate and collect carbon dioxide from Mars simulant gas. The carbon dioxide is fed with hydrogen into a Sabatier reactor where methane is produced. The APM is currently undergoing the final stages of testing at Kennedy Space Center prior to process integration testing with the other subunits of the pathfinder. The automation software for the APM cryocoolers was tested and found to perform nominally. The catalyst used for the Sabatier reactor was investigated to determine the factors contributing to catalyst failure. The results from the catalyst testing require further analysis, but it appears that the rapid change in temperature during reactor start up or the elevated operating temperature is responsible for the changes observed in the catalyst.

Photochemical aerosol formation in planetary atmospheres: A comparison between Pluto and Titan

NASA Astrophysics Data System (ADS)

Lavvas, Panayotis; Strobel, Darrell F.; Lellouch, Emmanuel; Gurwell, Mark A.; Cheng, Andrew F.; Summers, Michael; Gladstone, Randy

2016-10-01

The New Horizons mission observations have revealed us that Pluto's atmosphere is rich in photochemical hazes that extend to high altitudes above its surface [1], apparently similar to those observed in Titan's atmosphere [2].We use detailed models combining photochemistry and microphysics in order to simulate the aerosol formation and growth in Pluto's atmosphere, as performed for Titan's atmosphere [3]. Here we discuss the possible mechanisms leading to the formation of haze particles in Pluto's atmosphere, and we evaluate the contribution of different growth processes (e.g. coagulation vs. condensation) to the resulting particle properties.Moreover we investigate the role of these particles in the radiative balance of Pluto's atmosphere and we compare the resulting particle properties, with those retrieved for Titan's upper atmosphere based on Cassini observations [4]. We discuss the similarities and difference between Pluto's and Titan's aerosols.[1] Gladstone et al., 2016, Science, 351, 6271[2] West et al., 2015, Titan's Haze, in Titan, Interior, Surface, Atmosphere and Space environment, Cambridge University Press[3] Lavvas et al., 2013, PNAS, pnas.1217059110[4] Lavvas et al., 2015, DPS47, id.205.08

Assessment of atmospheric trace element concentrations by lichen-bag near an oil/gas pre-treatment plant in the Agri Valley (southern Italy)

NASA Astrophysics Data System (ADS)

Caggiano, R.; Trippetta, S.; Sabia, S.

2015-02-01

The atmospheric concentrations of 17 trace elements (Al, Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Ti and Zn) were measured by means of the "lichen-bag" technique in the Agri Valley (southern Italy). The lichen samples were collected from an unpolluted site located in Rifreddo forest (southern Italy), about 30 km away from the study area along the north direction. The bags were exposed to ambient air for 6 and 12 months. The exposed-to-control (EC) ratio values highlighted that the used lichen species were suitable for biomonitoring investigations. The results showed that the concentrations of almost all the examined trace elements increased with respect to the control after 6-12-month exposures. Furthermore, Ca, Al, Fe, K, Mg and S were the most abundant trace elements both in the 6-month and 12-month-exposed samples. Moreover, principal component analysis (PCA) results highlighted that the major sources of the measured atmospheric trace elements were related both to anthropogenic contributions due to traffic, combustion processes agricultural practices, construction and quarrying activities, and to natural contributions mainly represented by the re-suspension of local soil and road dusts. In addition, the contribution both of secondary atmospheric reactions involving Centro Olio Val d'Agri (COVA) plant emissions and the African dust long-range transport were also identified.

Assessment of atmospheric trace element concentrations by lichen-bag near an oil/gas pre-treatment plant in the Agri Valley (southern Italy)

NASA Astrophysics Data System (ADS)

Caggiano, R.; Trippetta, S.; Sabia, S.

2014-10-01

The atmospheric concentrations of 17 trace elements (Al, Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Ti and Zn) were measured by means of the "lichen-bag" technique in the Agri Valley (southern Italy). The lichen samples were collected from an unpolluted site located in Rifreddo forest (southern Italy). The bags were exposed to ambient air for 6 and 12 months. The exposed-to-control (EC) ratio values highlighted that the used lichen species were suitable for biomonitoring investigations. The results showed that the concentrations of almost all the examined trace elements increased with respect to the control after 6-12 month exposures. Furthermore, Ca, Al, Fe, K, Mg and S were the most abundant trace elements both in the 6 and 12 month-exposed samples. Moreover, principal component analysis (PCA) results highlighted that the major sources of the measured atmospheric trace elements were related both to anthropogenic contributions due to traffic, combustion processes, agricultural practices, construction and quarrying activities, and to natural contributions mainly represented by the re-suspension of local soil and road dusts. In addition, the contribution both of secondary atmospheric reactions involving Centro Olio Val d'Agri (COVA) plant emissions and the African dust long-range transport were also identified.

Influence of long-range transboundary transport on atmospheric water vapor mercury collected at the largest city of Tibet.

PubMed

Huang, Jie; Kang, Shichang; Tian, Lide; Guo, Junming; Zhang, Qianggong; Cong, Zhiyuan; Sillanpää, Mika; Sun, Shiwei; Tripathee, Lekhendra

2016-10-01

Monsoon circulation is an important process that affects long-range transboundary transport of anthropogenic contaminants such as mercury (Hg). During the Indian monsoon season of 2013, a total of 92 and 26 atmospheric water vapor samples were collected at Lhasa, the largest city of the Tibet, for Hg and major ions analysis, respectively. The relatively low pH/high electronic conductivity values, together with the fact that NH4(+) in atmospheric water vapor was even higher than that determined in precipitation of Lhasa, indicated the effects of anthropogenic perturbations through long-range transboundary atmospheric transport. Concentrations of Hg in atmospheric water vapor ranged from 2.5 to 73.7ngL(-1), with an average of 12.5ngL(-1). The elevated Hg and major ions concentrations, and electronic conductivity values were generally associated with weak acidic samples, and Hg mainly loaded with anthropogenic ions such as NH4(+). The results of principal component analysis and trajectory analysis suggested that anthropogenic emissions from the Indian subcontinent may have largely contributed to the determined Hg in atmospheric water vapor. Furthermore, our study reconfirmed that below-cloud scavenging contribution was significant for precipitation Hg in Lhasa, and evaluated that on average 74.1% of the Hg in precipitation could be accounted for by below-cloud scavenging. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical remote sensing of atmospheric compounds

NASA Astrophysics Data System (ADS)

Vazquez, Gabriel J.

1996-02-01

Human activities are altering the earth system at the local, regional, and global scales. It is therefore of the utmost importance to track the workings of mother earth in order to detect any changes at their early stages so that appropriate actions are taken to understand, assess, control or prevent the adverse effects. A number of deleterious effects to the environment can, at least in part, be ascribed to air pollution, namely, the thinning of the ozone layer, the related increase in the occurrence of skin cancer, the warming of the earth system, photochemical smog, acid rain/fog, acidification of soils and waters, forest decline, etc. It is therefore necessary to monitor the most relevant processes of the earth's atmosphere, namely, the energy input, the dynamics and the chemistry. In this contribution I mainly focus on the latter, specifically, on the measurement/monitoring of atmospheric compounds. To understand atmospheric chemistry and air pollution it is necessary to have reliable and accurate values of the mixing ratios of the numerous atmospheric gases and of their diurnal/seasonal variations and long-term trends. In this contribution I present an overview of the most relevant optical remote sensing techniques that are rapidly becoming the methods of choice to probe the chemical composition and physical state of the atmosphere, especially when high selectivity, sensitivity and fast-time response are required.

CAPSULE REPORT: SOURCES AND AIR EMISSION CONTROL TECHNOLOGIES AT WASTE MANAGEMENT FACILITIES

EPA Science Inventory

The chemicals processed during waste management operations can volatilize into the atmosphere and cause carcinogenic or other toxic effects or contribute to ozone formation. Regulations have been developed to control air emissions from these operations. The EPA has promulgated st...

LABORATORY AND COMPUTATIONAL INVESTIGATIONS OF THE ATMOSPHERIC CHEMISTRY OF KEY OXIDATION PRODUCTS CONTROLLING TROPOSPHERIC OZONE FORMATION

EPA Science Inventory

Major uncertainties remain in our ability to identify the key reactions and primary oxidation products of volatile hydrocarbons that contribute to ozone formation in the troposphere. To reduce these uncertainties, computational chemistry, mechanistic and process analysis techniqu...

Comparing Alternatives For Replacing Harmful Chemicals

NASA Technical Reports Server (NTRS)

Cruit, W.; Schutzenhofer, S.; Goldberg, B.; Everhart, K.

1995-01-01

Methodology developed to provide guidance for replacement of industrial chemicals that must be phased out by law because they are toxic and/or affect environment adversely. Chemicals and processes ranked numerically. Applies mostly to chemicals contributing to depletion of ozone in upper atmosphere; some other harmful chemicals included. Quality function deployment matrix format provides convenient way to compare alternative processes and chemicals. Overall rating at bottom of each process-and-chemical column indicates relative advantage.

The Role of Aerosols in Cloud Growth, Suppression, and Precipitation: Yoram Kaufman and his Contributions

NASA Technical Reports Server (NTRS)

King, Michael D.

2006-01-01

Aerosol particles are produced in the earth's atmosphere through both natural as well as manmade processes, and contribute profoundly to the (i) formation and characteristics of clouds, (ii) lifetime of clouds, (iii) optical and microphysical properties of clouds, (iv) human health through effects on air quality and the size of particulates as well as vectors for transport of pathogens, (v) climate response and feedbacks, (vi) precipitation, and (vii) harmful algal blooms. Without aerosol particles in the Earth's atmosphere, there would be no fogs, no clouds, ,no mists, and probably no rain, as noted as far back as 1880 by Scottish physicist John Aitken. With the modern development of instrumentation, both groundbased, airborne, and satellite-based, much progress has been made in linkng phenomena and processes together, and putting regional air quality characteristics and hypothesized cloud response into closer scrutiny and linkages. In h s presentation I will summarize the wide ranging contributions that Yoram Kaufman has made in ground-based (AERONET), aircraft field campaigns (such as SCAR-B and TARFOX), and, especially, satellite remote sensing (Landsat, MODIS, POLDER) to shed new light on this broad ranging and interdisciplinary field of cloud-aerosol-precipitation interactions.

Atmospheric mercury emissions from mine wastes and surrounding geologically enriched terrains

USGS Publications Warehouse

Gustin, M.S.; Coolbaugh, M.F.; Engle, M.A.; Fitzgerald, B.C.; Keislar, R.E.; Lindberg, S.E.; Nacht, D.M.; Quashnick, J.; Rytuba, J.J.; Sladek, C.; Zhang, H.; Zehner, R.E.

2003-01-01

Waste rock and ore associated with Hg, precious and base metal mining, and their surrounding host rocks are typically enriched in mercury relative to natural background concentrations (<0.1 ??g Hg g-1). Mercury fluxes to the atmosphere from mineralized areas can range from background rates (0-15 ng m-2 h-1) to tens of thousands of ng m-2 h-1. Mercury enriched substrate constitutes a long-term source of mercury to the global atmospheric mercury pool. Mercury emissions from substrate are influenced by light, temperature, precipitation, and substrate mercury concentration, and occur during the day and night. Light-enhanced emissions are driven by two processes: desorption of elemental mercury accumulated at the soil:air interface, and photo reduction of mercury containing phases. To determine the need for and effectiveness of regulatory controls on short-lived anthropogenic point sources the contribution of mercury from geologic non-point sources to the atmospheric mercury pool needs to be quantified. The atmospheric mercury contribution from small areas of mining disturbance with relatively high mercury concentrations are, in general, less than that from surrounding large areas of low levels of mercury enrichment. In the arid to semi-arid west-ern United States volatilization is the primary means by which mercury is released from enriched sites.

A Study on Various Meteoroid Disintegration Mechanisms as Observed from the Resolute Bay Incoherent Scatter Radar (RISR)

NASA Technical Reports Server (NTRS)

Malhotra, A.; Mathews, J. D.

2011-01-01

There has been much interest in the meteor physics community recently regarding the form that meteoroid mass flux arrives in the upper atmosphere. Of particular interest are the relative roles of simple ablation, differential ablation, and fragmentation in the meteoroid mass flux observed by the Incoherent Scatter Radars (ISR). We present here the first-ever statistical study showing the relative contribution of the above-mentioned three mechanisms. These are also one of the first meteor results from the newly-operational Resolute Bay ISR. These initial results emphasize that meteoroid disintegration into the upper atmosphere is a complex process in which all the three above-mentioned mechanisms play an important role though fragmentation seems to be the dominant mechanism. These results prove vital in studying how meteoroid mass is deposited in the upper atmosphere which has important implications to the aeronomy of the region and will also contribute in improving current meteoroid disintegration/ablation models.

Poleward upgliding Siberian atmospheric rivers over sea ice heat up Arctic upper air.

PubMed

Komatsu, Kensuke K; Alexeev, Vladimir A; Repina, Irina A; Tachibana, Yoshihiro

2018-02-13

We carried out upper air measurements with radiosondes during the summer over the Arctic Ocean from an icebreaker moving poleward from an ice-free region, through the ice edge, and into a region of thick ice. Rapid warming of the Arctic is a significant environmental issue that occurs not only at the surface but also throughout the troposphere. In addition to the widely accepted mechanisms responsible for the increase of tropospheric warming during the summer over the Arctic, we showed a new potential contributing process to the increase, based on our direct observations and supporting numerical simulations and statistical analyses using a long-term reanalysis dataset. We refer to this new process as "Siberian Atmospheric Rivers (SARs)". Poleward upglides of SARs over cold air domes overlying sea ice provide the upper atmosphere with extra heat via condensation of water vapour. This heating drives increased buoyancy and further strengthens the ascent and heating of the mid-troposphere. This process requires the combination of SARs and sea ice as a land-ocean-atmosphere system, the implication being that large-scale heat and moisture transport from the lower latitudes can remotely amplify the warming of the Arctic troposphere in the summer.

Atmospheric electricity at Durham: the scientific contributions and legacy of J. A. ("Skip") Chalmers (1904-1967)

NASA Astrophysics Data System (ADS)

Aplin, Karen L.

2018-03-01

John Alan Chalmers made major contributions to atmospheric electricity over almost 40 years spent at Durham University, UK. He is particularly remembered in the atmospheric science community for his accessible and insightful textbook, Atmospheric Electricity, and his work on corona currents, which are still regularly cited. He also supervised over 35 research students. This article discusses his background, scientific contributions, and significant legacy to modern atmospheric science within the context of a long and productive career spent at one of England's principal northern universities.

Estimation of mercury emission from different sources to atmosphere in Chongqing, China.

PubMed

Wang, Dingyong; He, Lei; Wei, Shiqiang; Feng, Xinbin

2006-08-01

This investigation presents a first assessment of the contribution to the regional mercury budget from anthropogenic and natural sources in Chongqing, an important industrial region in southwest China. The emissions of mercury to atmosphere from anthropogenic sources in the region were estimated through indirect approaches, i.e. using commonly acceptable emission factors method, which based on annual process throughputs or consumption for these sources. The natural mercury emissions were estimated from selected natural sources by the dynamic flux chamber technique. The results indicated that the anthropogenic mercury emissions totaled approximately 8.85 tons (t), more than 50% of this total originated in coal combustion and 23.7% of this total emission in the industrial process (include cement production, metal smelting and chemical industry). The natural emissions represented approximately 17% of total emissions (1.78 t yr(-1)). The total mercury emission to atmosphere in Chongqing in 2001 was 10.63 t.

Impact of a Regional Drought on Terrestrial Carbon Fluxes and Atmospheric Carbon: Results from a Coupled Carbon Cycle Model

NASA Technical Reports Server (NTRS)

Lee, Eunjee; Koster, Randal D.; Ott, Lesley E.; Weir, Brad; Mahanama, Sarith; Chang, Yehui; Zeng, Fan-Wei

2017-01-01

Understanding the underlying processes that control the carbon cycle is key to predicting future global change. Much of the uncertainty in the magnitude and variability of the atmospheric carbon dioxide (CO2) stems from uncertainty in terrestrial carbon fluxes, and the relative impacts of temperature and moisture variations on regional and global scales are poorly understood. Here we investigate the impact of a regional drought on terrestrial carbon fluxes and CO2 mixing ratios over North America using the NASA Goddard Earth Observing System (GEOS) Model. Results show a sequence of changes in carbon fluxes and atmospheric CO2, induced by the drought. The relative contributions of meteorological changes to the neighboring carbon dynamics are also presented. The coupled modeling approach allows a direct quantification of the impact of the regional drought on local and proximate carbon exchange at the land surface via the carbon-water feedback processes.

Absorption of Sunlight by Water Vapor in Cloudy Conditions: A Partial Explanation for the Cloud Absorption Anomaly

NASA Technical Reports Server (NTRS)

Crisp, D.

1997-01-01

The atmospheric radiative transfer algorithms used in most global general circulation models underestimate the globally-averaged solar energy absorbed by cloudy atmospheres by up to 25 W/sq m. The origin of this anomalous absorption is not yet known, but it has been attributed to a variety of sources including oversimplified or missing physical processes in these models, uncertainties in the input data, and even measurement errors. Here, a sophisticated atmospheric radiative transfer model was used to provide a more comprehensive description of the physical processes that contribute to the absorption of solar radiation by the Earth's atmosphere. We found that the amount of sunlight absorbed by a cloudy atmosphere is inversely proportional to the solar zenith angle and the cloud top height, and directly proportional to the cloud optical depth and the water vapor concentration within the clouds. Atmospheres with saturated, optically-thick, low clouds absorbed about 12 W/sq m more than clear atmospheres. This accounts for about 1/2 to 1/3 of the anomalous ab- sorption. Atmospheres with optically thick middle and high clouds usually absorb less than clear atmospheres. Because water vapor is concentrated within and below the cloud tops, this absorber is most effective at small solar zenith angles. An additional absorber that is distributed at or above the cloud tops is needed to produce the amplitude and zenith angle dependence of the observed anomalous absorption.

Glyoxal contribution to aerosols over Los Angeles

NASA Astrophysics Data System (ADS)

Balcerak, Ernie

2012-01-01

Laboratory and field studies have indicated that glyoxal (chemical formula OCHCHO), an atmospheric oxidation product of isoprene and aromatic compounds, may contribute to secondary organic aerosols in the atmosphere, which can block sunlight and affect atmospheric chemistry. Some aerosols are primary aerosols, emitted directly into the atmosphere, while others are secondary, formed through chemical reactions in the atmosphere. Washenfelder et al. describe in situ glyoxal measurements from Pasadena, Calif., near Los Angeles, made during summer 2010. They used three different methods to calculate the contribution of glyoxal to secondary atmospheric aerosol and found that it is responsible for 0-0.2 microgram per cubic meter, or 0-4%, of the secondary organic aerosol mass. The researchers also compared their results to those of a previous study that calculated the glyoxal contribution to aerosol for Mexico City. Mexico City had higher levels of organic aerosol mass from glyoxal. They suggest that the lower contribution of glyoxal to aerosol concentrations for Los Angeles may be due to differences in the composition or water content of the aerosols above the two cities. (Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD016314, 2011)

Quanitfying atmospheric nitrogen loading to watersheds using nitrate isotopes (15N, 17O, 18O)

NASA Astrophysics Data System (ADS)

Wankel, S. D.; Kendall, C.

2002-12-01

Over the past century, human activity has greatly increased the amount of reactive nitrogen (N) in the atmosphere and the N inputs to terrestrial and aquatic ecosystems. Recent studies in the northeastern US have indicated that atmospheric N deposition is a significant source to land and water in the region, with contributions ranging from 15 to 60%. Estimates of the importance of atmospheric N have been plagued with uncertainty, however, due to incomplete data from atmospheric monitoring networks, to the varied spatial and temporal scales of databases dealing with agricultural, population, and land use, and to simplifications that are necessary to describe the complex rates of N accumulation and transformation. The principal objective of this study is the evaluation of new stable isotope techniques for quantifying the relative contributions atmospheric sources of anthropogenic nitrogen to the landscape and to the total N exported from watersheds in the northeastern US. In the last decade, several studies have used d18O and d15N of nitrate to evaluate the relative contributions of riverine nitrate derived from atmospheric sources. Very recent advances in analytical techniques (by Michalski, Thiemens, and colleagues) that allow the analysis of nitrate for d17O have shown that atmospheric nitrate is labeled with an anomalous, non-terrestrial, d17O signature. Hence, we now have three isotopes of nitrate that can be used to quantify sources of riverine nitrate. To test whether the analysis of nitrate for d17O enhances our ability to quantify atmospheric contributions to the total nitrate exported by major river basins, we have initiated a pilot study of many of the major rivers in the Ohio Basin and the northeastern USA. Published studies in these basins suggest that nitrate from basins dominated by urban, forested, and undeveloped landuses frequently has d18O values consistent with significant input from atmospheric sources. Preliminary d18O and d15N of nitrate data from these basins, generated using the new microbial denitrifier method developed by Sigman et al (2001) and Casciotti et al (in press), are in general agreement with published values. We are in the process of testing a modification of the Sigman-Casciotti method that will permit the additional analysis of nitrate from very small samples for d17O. The results of this new method along with a preliminary assessment of the data generated with our pilot study will be presented.

Atmospheric correction for hyperspectral ocean color sensors

NASA Astrophysics Data System (ADS)

Ibrahim, A.; Ahmad, Z.; Franz, B. A.; Knobelspiesse, K. D.

2017-12-01

NASA's heritage Atmospheric Correction (AC) algorithm for multi-spectral ocean color sensors is inadequate for the new generation of spaceborne hyperspectral sensors, such as NASA's first hyperspectral Ocean Color Instrument (OCI) onboard the anticipated Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite mission. The AC process must estimate and remove the atmospheric path radiance contribution due to the Rayleigh scattering by air molecules and by aerosols from the measured top-of-atmosphere (TOA) radiance. Further, it must also compensate for the absorption by atmospheric gases and correct for reflection and refraction of the air-sea interface. We present and evaluate an improved AC for hyperspectral sensors beyond the heritage approach by utilizing the additional spectral information of the hyperspectral sensor. The study encompasses a theoretical radiative transfer sensitivity analysis as well as a practical application of the Hyperspectral Imager for the Coastal Ocean (HICO) and the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) sensors.

Long term observation and validation of windsat soil moisture data

USDA-ARS?s Scientific Manuscript database

The surface soil moisture controls surface energy budget. It is a key environmental variable in the coupled atmospheric and hydrological processes that are related to drought, heat waves and monsoon formation. Satellite remote sensing of soil moisture provides information that can contribute to unde...

Emissions of Bromine and Iodine from the Marine Environment in New Zealand

NASA Astrophysics Data System (ADS)

Martinez-Aviles, M.; Kreher, K.; Johnston, P. V.; Hay, T.; Thomas, A.; Schofield, R.

2009-12-01

As noted in the WMO/UNEP Scientific Assessment of Ozone Depletion: 2006, halogenated very short-lived substances (VSLS) contribute to the atmospheric budget of halogens and thereby lead to substantial decreases in ozone and increases in surface UV radiation in the tropics and mid-latitudes. Halogenated VSLS are primarily of natural origin; oceanic emissions constitute the largest source providing 90-95% of the total global flux to the atmosphere. Macro algae in the ocean appear to be an important source of polyhalogenated VSLS. Oxidation of halogenated VSLS in the atmosphere (i.e. photolysis and reactions with OH) produces halogen oxide radicals (e.g. ClO, BrO, IO) which have been suggested as the main component of gas-phase halogens. Countries with long coastlines and little land suitable for forestation are investigating the possibility of industrial scale marine kelp farming as a means of carbon sequestration. This marine analogy of the Kyoto Protocol forest has been thought as a means to contribute to climate change mitigation. Knowledge of how natural emissions of VSLS will respond to both the drivers of climate change (e.g. changes in CO2 and land use) and to the consequences of climate change (e.g. changes in sea surface temperature and wind stress) is very limited. As a result, it is imperative that observational studies are performed to quantify the contributions of these natural VSLS to halogen loading in the troposphere and, subsequently, in the stratosphere. For this, transport and degradation processes of the source gases and product gases need to be studied and quantified. A key question surfacing from the WMO Assessment is to what extent halogenated VSLS contribute to atmospheric Bry and Iy. During a field campaign conducted during the spring of 2009, measurements of BrO and IO were made along the coastline of the South Island of New Zealand using a portable Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) spectrometer with the aim of determining coastal sites where high active halogen release could be observed. The selected sites had high biomass concentration of marine algae that would be exposed by low tides. Local macro algae type, tidal height, sunlight, temperature, and wind speed were recorded and correlated to the resulting data in order to better understand the environmental factors that modulate the emissions of halogen oxides from the marine environment to the troposphere. Results of this multi-disciplinary approach to studying brominated VSLS and their atmospheric implications are presented. As well, the chemical processes taking place and producing these halogen oxides are discussed in a thorough manner. This study contributes to a better understanding of the origin of bromine and iodine in the lowermost atmosphere (i.e. marine boundary layer). Particularly, the role that natural emissions of halogenated VSLS from the ocean may play in the halogen budget of the lower atmosphere is addressed by quantitatively understanding key links in this chain so that its potential future impacts on atmospheric chemistry, surface UV radiation, and the biosphere can be thoroughly assessed.

Atmospheric mercury deposition and its contribution of the regional atmospheric transport to mercury pollution at a national forest nature reserve, southwest China.

PubMed

Ma, Ming; Wang, Dingyong; Du, Hongxia; Sun, Tao; Zhao, Zheng; Wei, Shiqing

2015-12-01

Atmospheric mercury deposition by wet and dry processes contributes to the transformation of mercury from atmosphere to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to subtropical forests were identified in this study. Throughfall and open field precipitation samples were collected in 2012 and 2013 using precipitation collectors from forest sites located across Mt. Jinyun in southwest China. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy was the primary factor on THg and MeHg deposition. Simultaneously, continuous measurements of atmospheric gaseous elemental mercury (GEM) were carried out from March 2012 to February 2013 at the summit of Mt. Jinyun. Atmospheric GEM concentrations averaged 3.8 ± 1.5 ng m(-3), which was elevated compared with global background values. Sources identification indicated that both regional industrial emissions and long-range transport of Hg from central, northeast, and southwest China were corresponded to the elevated GEM levels. Precipitation deposition fluxes of THg and MeHg in Mt. Jinyun were slightly higher than those reported in Europe and North America, whereas total fluxes of MeHg and THg under forest canopy on Mt. Jiuyun were 3 and 2.9 times of the fluxes of THg in wet deposition in the open. Highly elevated litterfall deposition fluxes suggest that even in remote forest areas of China, deposition of atmospheric Hg(0) via uptake by vegetation leaf may be a major pathway for the deposition of atmospheric Hg. The result illustrates that areas with greater atmospheric pollution can be expected to have greater fluxes of Hg to soils via throughfall and litterfall.

MAVEN Observations of Escaping Planetary Ions from the Martian Atmosphere: Mass, Velocity, and Spatial Distributions

NASA Astrophysics Data System (ADS)

Dong, Yaxue; Fang, Xiaohua; Brain, D. A.; McFadden, James P.; Halekas, Jasper; Connerney, Jack

2015-04-01

The Mars-solar wind interaction accelerates and transports planetary ions away from the Martian atmosphere through a number of processes, including ‘pick-up’ by electromagnetic fields. The MAVEN spacecraft has made routine observations of escaping planetary ions since its arrival at Mars in September 2014. The SupraThermal And Thermal Ion Composition (STATIC) instrument measures the ion energy, mass, and angular spectra. It has detected energetic planetary ions during most of the spacecraft orbits, which are attributed to the pick-up process. We found significant variations in the escaping ion mass and velocity distributions from the STATIC data, which can be explained by factors such as varying solar wind conditions, contributions of particles from different source locations and different phases during the pick-up process. We also study the spatial distributions of different planetary ion species, which can provide insight into the physics of ion escaping process and enhance our understanding of atmospheric erosion by the solar wind. Our results will be further interpreted within the context of the upstream solar wind conditions measured by the MAVEN Solar Wind Ion Analyzer (SWIA) instrument and the magnetic field environment measured by the Magnetometer (MAG) instrument. Our study shows that the ion spatial distribution in the Mars-Sun-Electric-Field (MSE) coordinate system and the velocity space distribution with respect to the local magnetic field line can be used to distinguish the ions escaping through the polar plume and those through the tail region. The contribution of the polar plume ion escape to the total escape rate will also be discussed.

Simple aerosol correction technique based on the spectral relationships of the aerosol multiple-scattering reflectances for atmospheric correction over the oceans.

PubMed

Ahn, Jae-Hyun; Park, Young-Je; Kim, Wonkook; Lee, Boram

2016-12-26

An estimation of the aerosol multiple-scattering reflectance is an important part of the atmospheric correction procedure in satellite ocean color data processing. Most commonly, the utilization of two near-infrared (NIR) bands to estimate the aerosol optical properties has been adopted for the estimation of the effects of aerosols. Previously, the operational Geostationary Color Ocean Imager (GOCI) atmospheric correction scheme relies on a single-scattering reflectance ratio (SSE), which was developed for the processing of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data to determine the appropriate aerosol models and their aerosol optical thicknesses. The scheme computes reflectance contributions (weighting factor) of candidate aerosol models in a single scattering domain then spectrally extrapolates the single-scattering aerosol reflectance from NIR to visible (VIS) bands using the SSE. However, it directly applies the weight value to all wavelengths in a multiple-scattering domain although the multiple-scattering aerosol reflectance has a non-linear relationship with the single-scattering reflectance and inter-band relationship of multiple scattering aerosol reflectances is non-linear. To avoid these issues, we propose an alternative scheme for estimating the aerosol reflectance that uses the spectral relationships in the aerosol multiple-scattering reflectance between different wavelengths (called SRAMS). The process directly calculates the multiple-scattering reflectance contributions in NIR with no residual errors for selected aerosol models. Then it spectrally extrapolates the reflectance contribution from NIR to visible bands for each selected model using the SRAMS. To assess the performance of the algorithm regarding the errors in the water reflectance at the surface or remote-sensing reflectance retrieval, we compared the SRAMS atmospheric correction results with the SSE atmospheric correction using both simulations and in situ match-ups with the GOCI data. From simulations, the mean errors for bands from 412 to 555 nm were 5.2% for the SRAMS scheme and 11.5% for SSE scheme in case-I waters. From in situ match-ups, 16.5% for the SRAMS scheme and 17.6% scheme for the SSE scheme in both case-I and case-II waters. Although we applied the SRAMS algorithm to the GOCI, it can be applied to other ocean color sensors which have two NIR wavelengths.

Unravelling connections between river flow and large-scale climate: experiences from Europe

NASA Astrophysics Data System (ADS)

Hannah, D. M.; Kingston, D. G.; Lavers, D.; Stagge, J. H.; Tallaksen, L. M.

2016-12-01

The United Nations has identified better knowledge of large-scale water cycle processes as essential for socio-economic development and global water-food-energy security. In this context, and given the ever-growing concerns about climate change/ variability and human impacts on hydrology, there is an urgent research need: (a) to quantify space-time variability in regional river flow, and (b) to improve hydroclimatological understanding of climate-flow connections as a basis for identifying current and future water-related issues. In this paper, we draw together studies undertaken at the pan-European scale: (1) to evaluate current methods for assessing space-time dynamics for different streamflow metrics (annual regimes, low flows and high flows) and for linking flow variability to atmospheric drivers (circulation indices, air-masses, gridded climate fields and vapour flux); and (2) to propose a plan for future research connecting streamflow and the atmospheric conditions in Europe and elsewhere. We believe this research makes a useful, unique contribution to the literature through a systematic inter-comparison of different streamflow metrics and atmospheric descriptors. In our findings, we highlight the need to consider appropriate atmospheric descriptors (dependent on the target flow metric and region of interest) and to develop analytical techniques that best characterise connections in the ocean-atmosphere-land surface process chain. We call for the need to consider not only atmospheric interactions, but also the role of the river basin-scale terrestrial hydrological processes in modifying the climate signal response of river flows.

Surface-initiated graft polymerization on multiwalled carbon nanotubes pretreated by corona discharge at atmospheric pressure.

PubMed

Xu, Lihua; Fang, Zhengping; Song, Ping'an; Peng, Mao

2010-03-01

Surface-initiated graft polymerization on multi-walled carbon nanotubes pretreated with a corona discharge at atmospheric pressure was explored. The mechanism of the corona-discharge-induced graft polymerization is discussed. The results indicate that MWCNTs were encapsulated by poly(glycidyl methacrylate) (PGMA), demonstrating the formation of PGMA-grafted MWCNTs (PGMA-g-MWCNTs), with a grafting ratio of about 22 wt%. The solubility of PGMA-g-MWCNTs in ethanol was dramatically improved compared to pristine MWCNTs, which could contribute to fabricating high-performance polymer/MWCNTs nanocomposites in the future. Compared with most plasma processes, which operate at low pressures, corona discharge has the merit of working at atmospheric pressure.

Zero-Gravity Atmospheric Cloud Physics Experiment Laboratory engineering concepts/design tradeoffs. Volume 1: Study results

NASA Technical Reports Server (NTRS)

Greco, R. V.; Eaton, L. R.; Wilkinson, H. C.

1974-01-01

The work is summarized which was accomplished from January 1974 to October 1974 for the Zero-Gravity Atmospheric Cloud Physics Laboratory. The definition and development of an atmospheric cloud physics laboratory and the selection and delineation of candidate experiments that require the unique environment of zero gravity or near zero gravity are reported. The experiment program and the laboratory concept for a Spacelab payload to perform cloud microphysics research are defined. This multimission laboratory is planned to be available to the entire scientific community to utilize in furthering the basic understanding of cloud microphysical processes and phenomenon, thereby contributing to improved weather prediction and ultimately to provide beneficial weather control and modification.

Role of Multiple Atmospheric Reflections in Formation of Electron Distribution Function in the Diffuse Aurora Region. Chapter 9

NASA Technical Reports Server (NTRS)

Khazanov, George V.; Himwich, Elizabeth W.; Glocer, Alex; Sibeck, David G.

2015-01-01

The precipitation of high-energy magnetospheric electrons (E greater than 500-600 electronvolts) in the diffuse aurora contributes significant energy flux into Earth's ionosphere. In the diffuse aurora, precipitating electrons initially injected from the plasmasheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These initially precipitating electrons of magnetospheric origin can be additionally reflected back into the magnetosphere by the two magnetically conjugated atmospheres, leading to a series of multiple reflections that can greatly influence the initially precipitating flux at the upper ionospheric boundary (700-800 kilometers) and the resultant population of secondary electrons and electrons cascading toward lower energies. We present the solution of the Boltzmann.Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E is less than or equal to 600 electronvolts) and their energy interplay in the magnetosphere and two conjugated ionospheres. This solution takes into account the role of multiple atmospheric reflections of the precipitated electrons that were initially moved into the loss cone via wave.particle interaction processes in Earth's plasmasheet.

Lord Kelvin's atmospheric electricity measurements

NASA Astrophysics Data System (ADS)

Aplin, Karen; Harrison, R. Giles; Trainer, Matthew; Hough, James

2013-04-01

Lord Kelvin (William Thomson), one of the greatest Victorian scientists, made a substantial but little-recognised contribution to geophysics through his work on atmospheric electricity. He developed sensitive instrumentation for measuring the atmospheric electric field, including invention of a portable electrometer, which made mobile measurements possible for the first time. Kelvin's measurements of the atmospheric electric field in 1859, made during development of the portable electrometer, can be used to deduce the substantial levels of particulate pollution blown over the Scottish island of Arran from the industrial mainland. Kelvin was also testing the electrometer during the largest solar flare ever recorded, the "Carrington event" in the late summer of 1859. Subsequently, Lord Kelvin also developed a water dropper sensor, and employed photographic techniques for "incessant recording" of the atmospheric electric field, which led to the long series of measurements recorded at UK observatories for the remainder of the 19th and much of the 20th century. These data sets have been valuable in both studies of historical pollution and cosmic ray effects on atmospheric processes.

Theoretical investigation on iodine oxides formation and their role in the production of atmospheric aerosols

NASA Astrophysics Data System (ADS)

Galvez, Óscar; Gomez, Pedro C.; Gomez-Martin, Juan C.; Saiz-Lopez, Alfonso; Pacios, Luis F.

2013-04-01

Atmospheric iodine has received considerable attention in the past two decades due to both its potential role in the catalytic destruction of ozone (1) and its contribution to the formation of ultrafine particles (2). Seaweeds, marine phytoplankton, and abiotic processes release iodocarbons and I2 to the atmosphere, which are photo-oxidized giving iodine oxides that polymerize to finally form iodine oxide particles (IOPs). In the last years, some laboratory studies have been carried out to investigate this process (see e.g. (3)), however the complete mechanism of formation of such particles and the role of water, and other condensable vapors, in this process have not yet been elucidated. In this context, quantum calculations could help to unravel essential steps of these processes and to evaluate relevant physicochemical properties that can be incorporated into atmospheric models. In this contribution, we show results of a theoretical study on different reactions that iodine oxides, in the presence of water, can undergo to form IOPs. Thermodynamic and kinetic properties of these reactions have been obtained at high level ab initio correlated calculations that included relativistic corrections. In these calculations, we have used a relativistic effective potential (REP) and REP-optimized basis sets for iodine atom developed in our group, which have previously been employed in a theoretical study about several iodinated species (4). (1) Saiz-Lopez, A.; Mahajan, A.S.; Salmon, R.A.; Bauguitte, J.B.; Jones, A.E.; Roscoe, H.K.; Plane, J.M.C. Science 2007, 317, 348-351 (2) O'Dowd, C.D.; Jimenez, J.L.; Bahreini, R.; Flagan, R.C.; Seinfeld, J.H.; Hämeri, K.; Pirjola, L.; Kulmala, M.; Jennings, S.G.; Hoffmann, T. Nature, 2002, 417, 632-636. (3) Saunders, R.W.; Kumar, R.; Gómez Martin, J.C.; Mahajan, A.S.; Murray, B.J.; Plane, J.M.C. Z. Phys. Chem. 2010, 224, 1095-1117. (4) Pacios, L.F.; Gálvez, O. J. Chem. Theory Comput., 2010, 6, 1738-1752.

Are Changing Emission Patterns Across the Northern Hemisphere Influencing Long-range Transport Contributions to Background Air Pollution?

EPA Science Inventory

Air pollution reduction strategies for a region are complicated not only by the interplay of local emissions sources and several complex physical, chemical, dynamical processes in the atmosphere, but also hemispheric background levels of pollutants. Contrasting changes in emissio...

COMPOSITION OF PM 2.5 DURING THE SUMMER OF 2003 IN RESEARCH TRIANGLE PARK, NORTH CAROLINA

EPA Science Inventory

Ambient PM_2.5 contains a complex mixture of organic and inorganic compounds which may be derived from primary emission to the atmosphere or from secondary reaction processes. Determining the relative contributions of primary emissions versus secondary production and u...

Photon-stimulated desorption as a substantial source of sodium in the lunar atmosphere.

PubMed

Yakshinskiy, B V; Madey, T E

1999-08-12

Mercury and the Moon both have tenuous atmospheres that contain atomic sodium and potassium. These chemicals must be continuously resupplied, as neither body can retain the atoms for more than a few hours. The mechanisms proposed to explain the resupply include sputtering of the surface by the solar wind, micrometeorite impacts, thermal desorption and photon-stimulated desorption. But there are few data and no general agreement about which processes dominate. Here we report laboratory studies of photon-stimulated desorption of sodium from surfaces that simulate lunar silicates. We find that bombardment of such surfaces at temperatures of approximately 250 K by ultraviolet photons (wavelength lambda < 300 nm) causes very efficient desorption of sodium atoms, induced by electronic excitations rather than by thermal processes or momentum transfer. The flux at the lunar surface of ultraviolet photons from the Sun is sufficient to ensure that photon-stimulated desorption of sodium contributes substantially to the Moon's atmosphere. On Mercury, solar heating of the surface implies that thermal desorption will also be an important source of atmospheric sodium.

Attribution of regional flood changes based on scaling fingerprints

NASA Astrophysics Data System (ADS)

Viglione, A.; Merz, B.; Dung, N.; Parajka, J.; Nester, T.; Bloeschl, G.

2017-12-01

Changes in the river flood regime may be due to atmospheric processes (e.g., increasing precipitation), catchment processes (e.g., soil compaction associated with land use change), and river system processes (e.g., loss of retention volume in the floodplains). We propose a framework for attributing flood changes to these drivers based on a regional analysis. We exploit the scaling characteristics (i.e., fingerprints) with catchment area of the effects of the drivers on flood changes. The estimation of their relative contributions is framed in Bayesian terms. Analysis of a synthetic, controlled case suggests that the accuracy of the regional attribution increases with increasing number of sites and record lengths, decreases with increasing regional heterogeneity, increases with increasing difference of the scaling fingerprints, and decreases with an increase of their prior uncertainty. The applicability of the framework is illustrated for a case study set in Austria, where positive flood trends have been observed at many sites in the past decades. The individual scaling fingerprints related to the atmospheric, catchment, and river system processes are estimated from rainfall data and simple hydrological modeling. Although the distributions of the contributions are rather wide, the attribution identifies precipitation change as the main driver of flood change in the study region.

Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere.

PubMed

Gorski, Galen; Strong, Courtenay; Good, Stephen P; Bares, Ryan; Ehleringer, James R; Bowen, Gabriel J

2015-03-17

Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. We show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration of water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. Our findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.

Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

PubMed Central

Gorski, Galen; Strong, Courtenay; Good, Stephen P.; Bares, Ryan; Ehleringer, James R.; Bowen, Gabriel J.

2015-01-01

Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. We show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration of water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. Our findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry. PMID:25733906

Proceedings: Workshop on the Need for Lightning Observations from Space

NASA Technical Reports Server (NTRS)

Christensen, L. S. (Editor); Frost, W. (Editor); Vaughan, W. W. (Editor)

1979-01-01

The results of the Workshop on the Need for Lightning Observations from Space held February 13-15, 1979, at the University of Tennessee Space Institute, Tullahoma, Tennessee are presented. The interest and active involvement by the engineering, operational, and scientific participants in the workshop demonstrated that lightning observations from space is a goal well worth pursuing. The unique contributions, measurement requirements, and supportive research investigations were defined for a number of important applications. Lightning has a significant role in atmospheric processes and needs to be systematically investigated. Satellite instrumentation specifically designed for indicating the characteristics of lightning are of value in severe storms research, in engineering and operational problem areas, and in providing information on atmospheric electricity and its role in meteorological processes.

Carbon Disulfide (CS2) Mechanisms in Formation of Atmospheric Carbon Dioxide (CO2) Formation from Unconventional Shale Gas Extraction and Processing Operations and Global Climate Change.

PubMed

Rich, Alisa L; Patel, Jay T

2015-01-01

Carbon disulfide (CS2) has been historically associated with the production of rayon, cellophane, and carbon tetrachloride. This study identifies multiple mechanisms by which CS2 contributes to the formation of CO2 in the atmosphere. CS2 and other associated sulfide compounds were found by this study to be present in emissions from unconventional shale gas extraction and processing (E&P) operations. The breakdown products of CS2; carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) are indirect greenhouse gases (GHGs) that contribute to CO2 levels in the atmosphere. The heat-trapping nature of CO2 has been found to increase the surface temperature, resulting in regional and global climate change. The purpose of this study is to identify five mechanisms by which CS2 and the breakdown products of CS2 contribute to atmospheric concentrations of CO2. The five mechanisms of CO2 formation are as follows: Chemical Interaction of CS2 and hydrogen sulfide (H2S) present in natural gas at high temperatures, resulting in CO2 formation;Combustion of CS2 in the presence of oxygen producing SO2 and CO2;Photolysis of CS2 leading to the formation of COS, CO, and SO2, which are indirect contributors to CO2 formation;One-step hydrolysis of CS2, producing reactive intermediates and ultimately forming H2S and CO2;Two-step hydrolysis of CS2 forming the reactive COS intermediate that reacts with an additional water molecule, ultimately forming H2S and CO2. CS2 and COS additionally are implicated in the formation of SO2 in the stratosphere and/or troposphere. SO2 is an indirect contributor to CO2 formation and is implicated in global climate change.

Identification of atmospheric mercury sources and transport pathways on local and regional sales

NASA Astrophysics Data System (ADS)

Gratz, Lynne E.

Mercury (Hg) is a hazardous air pollutant and bioaccumulative neurotoxin whose intricate atmospheric chemistry complicates our ability to define Hg source-receptor relationships on all scales. Our detailed measurements of Hg in its different forms together with atmospheric tracers have improved our understanding of Hg chemistry and transport. Daily-event precipitation samples collected from 1995 to 2006 in Underhill, VT were examined to identify Hg wet deposition trends and source influences. Analysis revealed that annual Hg deposition at this fairly remote location did not vary significantly over the 12-year period. While a decreasing trend in volume-weighted mean Hg concentration was observed, Hg wet deposition did not decline as transport of emissions from the Midwest and along the Atlantic Coast consistently contributed to the largest observed Hg wet deposition events. Receptor modeling of Hg and trace elements in precipitation indicated that ---60% of Hg wet deposition at Underhill could be attributed to emissions from coal-fired utility boilers (CFUBs), and their contribution to Hg wet deposition did not change significantly over time. Hybrid-receptor modeling further defined these CFUBs to be located predominantly in the Midwestern U.S. Atmospheric Hg chemistry and transport from the Chicago urban/industrial area was the focus of speciated Hg measurements performed in the southern Lake Michigan basin during summer 2007. Transport from Chicago, IL to Holland, MI occurred during 27% of the study period, resulting in a five-fold increase in divalent reactive gaseous Hg (RGM) at the downwind Holland site. Dispersion modeling of case study periods demonstrated that under southwesterly flow approximately half of the RGM in Holland could be attributed to primary RGM emissions from Chicago after transport and dispersion, with the remainder due to Hg0 oxidation in the atmosphere en route. Precipitation and ambient vapor phase samples were also collected in Chicago, Holland, and Dexter, MI and analyzed for Hg isotopes. The Hg isotopic fractionation observed in atmospheric samples was in contrast to a recently published report which predicted that aqueous photoreduction may be a dominant source of atmospheric Hg. Our results suggest that other redox reactions and source related processes likely contribute to isotopic fractionation of atmospheric Hg.

Earth cloud, aerosol, and radiation explorer optical payload development status

NASA Astrophysics Data System (ADS)

Hélière, A.; Wallace, K.; Pereira do Carmo, J.; Lefebvre, A.

2017-09-01

The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop as part of ESA's Living Planet Programme, the third Earth Explorer Core Mission, EarthCARE, with the ojective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earth's atmosphere. EarthCARE payload consists of two active and two passive instruments: an ATmospheric LIDar (ATLID), a Cloud Profiling Radar (CPR), a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer (BBR). The four instruments data are processed individually and in a synergetic manner to produce a large range of products, which include vertical profiles of aerosols, liquid water and ice, observations of cloud distribution and vertical motion within clouds, and will allow the retrieval of profiles of atmospheric radiative heating and cooling. MSI is a compact instrument with a 150 km swath providing 500 m pixel data in seven channels, whose retrieved data will give context to the active instrument measurements, as well as providing cloud and aerosol information. BBR measures reflected solar and emitted thermal radiation from the scene. Operating in the UV range at 355 nm, ATLID provides atmospheric echoes from ground to an altitude of 40 km. Thanks to a high spectral resolution filtering, the lidar is able to separate the relative contribution of aerosol and molecular scattering, which gives access to aerosol optical depth. Co-polarised and cross-polarised components of the Mie scattering contribution are measured on dedicated channels. This paper will provide a description of the optical payload implementation, the design and characterisation of the instruments.

Observed Hydrologic Impacts of Landfalling Atmospheric Rivers in the Salt and Verde River Basins of Arizona, United States

NASA Astrophysics Data System (ADS)

Demaria, Eleonora M. C.; Dominguez, Francina; Hu, Huancui; von Glinski, Gerd; Robles, Marcos; Skindlov, Jonathan; Walter, James

2017-12-01

Atmospheric rivers (ARs), narrow atmospheric water vapor corridors, can contribute substantially to winter precipitation in the semiarid Southwest U.S., where natural ecosystems and humans compete for over-allocated water resources. We investigate the hydrologic impacts of 122 ARs that occurred in the Salt and Verde river basins in northeastern Arizona during the cold seasons from 1979 to 2009. We focus on the relationship between precipitation, snow water equivalent (SWE), soil moisture, and extreme flooding. During the cold season (October through March) ARs contribute an average of 25%/29% of total seasonal precipitation for the Salt/Verde river basins, respectively. However, they contribute disproportionately to total heavy precipitation and account for 64%/72% of extreme total daily precipitation (exceeding the 98th percentile). Excess precipitation during AR occurrences contributes to snow accumulation; on the other hand, warmer than normal temperatures during AR landfallings are linked to rain-on-snow processes, an increase in the basins' area contributing to runoff generation, and higher melting lines. Although not all AR events are linked to extreme flooding in the basins, they do account for larger runoff coefficients. On average, ARs generate 43% of the annual maximum flows for the period studied, with 25% of the events exceeding the 10 year return period. Our analysis shows that the devastating 1993 flooding event in the region was caused by AR events. These results illustrate the importance of AR activity on the hydrology of inland semiarid regions: ARs are critical for water resources, but they can also lead to extreme flooding that affects infrastructure and human activities.

Contributions of Nimbus 7 TOMS Data to Volcanic Study and Hazard Mitigation

NASA Technical Reports Server (NTRS)

Krueger, Arlin J.; Bluth, G. J. S.; Schaefer, S. A.

1998-01-01

Nimbus TOMS data have led to advancements among many volcano-related scientific disciplines, from the initial ability to quantify SO2 clouds leading to derivations of eruptive S budgets and fluxes, to tracking of individual clouds, assessing global volcanism and atmospheric impacts. Some of the major aspects of TOMS-related research, listed below, will be reviewed and updated: (1) Measurement of volcanic SO2 clouds: Nimbus TOMS observed over 100 individual SO2 clouds during its mission lifetime; large explosive eruptions are now routinely and reliably measured by satellite. (2) Eruption processes: quantification of SO2 emissions have allowed assessments of eruption sulfur budgets, the evaluation of "excess" sulfur, and inferences of H2S emissions. (3) Detection of ash: TOMS data are now used to detect volcanic particulates in the atmosphere, providing complementary analyses to infrared methods of detection. Paired TOMS and AVHRR studies have provided invaluable information on volcanic cloud compositions and processes. (4) Cloud tracking and hazard mitigation: volcanic clouds can be considered gigantic tracers in the atmosphere, and studies of the fates of these clouds have led to new knowledge of their physical and chemical dispersion in the atmosphere for predictive models. (5) Global trends: the long term data set has provided researchers an unparalleled record of explosive volcanism, and forms a key component in assessing annual to decadal trends in global S emissions. (6) Atmospheric impacts: TOMS data have been linked to independent records of atmospheric change, in order to compare cause and effect processes following a massive injection of SO2 into the atmosphere. (7) Future TOMS instruments and applications: Nimbus TOMS has given way to new satellite platforms, with several wavelength and resolution modifications. New efforts to launch a geostationary TOMS could provide unprecedented observations of volcanic activity.

Assessing uncertainty and sensitivity of model parameterizations and parameters in WRF affecting simulated surface fluxes and land-atmosphere coupling over the Amazon region

NASA Astrophysics Data System (ADS)

Qian, Y.; Wang, C.; Huang, M.; Berg, L. K.; Duan, Q.; Feng, Z.; Shrivastava, M. B.; Shin, H. H.; Hong, S. Y.

2016-12-01

This study aims to quantify the relative importance and uncertainties of different physical processes and parameters in affecting simulated surface fluxes and land-atmosphere coupling strength over the Amazon region. We used two-legged coupling metrics, which include both terrestrial (soil moisture to surface fluxes) and atmospheric (surface fluxes to atmospheric state or precipitation) legs, to diagnose the land-atmosphere interaction and coupling strength. Observations made using the Department of Energy's Atmospheric Radiation Measurement (ARM) Mobile Facility during the GoAmazon field campaign together with satellite and reanalysis data are used to evaluate model performance. To quantify the uncertainty in physical parameterizations, we performed a 120 member ensemble of simulations with the WRF model using a stratified experimental design including 6 cloud microphysics, 3 convection, 6 PBL and surface layer, and 3 land surface schemes. A multiple-way analysis of variance approach is used to quantitatively analyze the inter- and intra-group (scheme) means and variances. To quantify parameter sensitivity, we conducted an additional 256 WRF simulations in which an efficient sampling algorithm is used to explore the multiple-dimensional parameter space. Three uncertainty quantification approaches are applied for sensitivity analysis (SA) of multiple variables of interest to 20 selected parameters in YSU PBL and MM5 surface layer schemes. Results show consistent parameter sensitivity across different SA methods. We found that 5 out of 20 parameters contribute more than 90% total variance, and first-order effects dominate comparing to the interaction effects. Results of this uncertainty quantification study serve as guidance for better understanding the roles of different physical processes in land-atmosphere interactions, quantifying model uncertainties from various sources such as physical processes, parameters and structural errors, and providing insights for improving the model physics parameterizations.

In Memoriam - Marvin L. Wesely.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaffney, J. S.; Environmental Research

2003-06-01

Marvin L. Wesely, senior meteorologist at Argonne National Laboratory, died January 20, 2003, from a rare form of heart cancer. He was an internationally know and highly respected leader in the scientific measurement and modeling of atmospheric boundary layer turbulence and dry deposition of air pollutants. His fundamental contributions in the development of methodologies for fomulating dry deposition processes are used in atmospheric and biospheric models applied on all scales, worldwide. His extensive research aimed at finding solutions to such environmental problems as air pollution and global warming resulted in more than 150 published articles. Dr. Wesley was also anmore » editor for the Journal of Applied Meteorology and chief scientist of the atmospheric chemistry program in Washington, DC.« less

The Impacts of California's San Francisco Bay Area Gap on Precipitation Observed in the Sierra Nevada during Hmt and Calwater

NASA Astrophysics Data System (ADS)

White, A. B.; Neiman, P. J.; Creamean, J.; Coleman, T.; Ralph, F. M.; Prather, K. A.

2014-12-01

The National Oceanic and Atmospheric Administration (NOAA)'s Hydrometeorology Testbed (HMT; hmt.noaa.gov) conducts research on the meteorological and microphysical processes contributing to orographically enhanced precipitation. Some of HMT's precipitation research has been focused on a shallow rainfall process driven by collision-coalescence that often is undetected by the National Weather Service's operational scanning radar network, especially in the Western U.S., but that can produce rain rates that are capable of creating floods. Originally it was believed that this shallow rainfall process would occur more prevalently over the coastal mountain ranges than over the Sierra Nevada, since the higher mountains of the Sierra would force deeper atmospheric ascent and produce deeper precipitating cloud systems that extend well above the melting level. This notion was disproved when it was recently discovered that a site in the northern Sierra had nearly as large of a contribution to seasonal rainfall from this shallow rainfall process, on average, as did a habitually wet site in the coast range of Sonoma County north of San Francisco. This work examines this apparent paradox using observations collected during HMT and CalWater field campaigns. In particular, a case study from CalWater is used to highlight the interaction between a landfalling atmospheric river (AR) and the Sierra Barrier Jet (SBJ). The gap in coastal terrain associated with the San Francisco Bay area is shown to allow unprocessed, moisture-enhanced flow in the AR to reach the northern Sierra site, where the SBJ provides a lifting mechanism to create enhanced orographic precipitation as compared to a site in the southern Sierra, where AR-associated dynamics are weaker and AR flow is modified by upstream coastal terrain.

North America's net terrestrial CO2 exchange with the atmosphere 1990-2009

Treesearch

A.W. King; R.J. Andres; K J. Davis; M. Hafer; D.J. Hayes; D.N. Huntzinger; B. de Jong; W.A. Kurz; A.D. McGuire; R. Vargas; Y. Wei; T.O. West; C.W. Woodall

2015-01-01

Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) project, this paper provides a synthesis of net...

Molecular characterization of primary humic-like substances in fine smoke particles by thermochemolysis-gas chromatography-mass spectrometry

NASA Astrophysics Data System (ADS)

Fan, Xingjun; Wei, Siye; Zhu, Mengbo; Song, Jianzhong; Peng, Ping'an

2018-05-01

In this study, the molecular structures of primary humic-like substances (HULIS) in fine smoke particles emitted from the combustion of biomass materials (including rice straw, corn straw, and pine branches) and coal, and atmospheric HULIS were determined by off-line tetramethylammonium hydroxide thermochemolysis coupled with gas chromatography and mass spectrometry (TMAH-GC/MS). A total of 89 pyrolysates were identified by the thermochemolysis of primary and atmospheric HULIS. The main groups were polysaccharide derivatives, N-containing compounds, lignin derivatives, aromatic acid methyl ester, aliphatic acid methyl ester, and diterpenoid derivatives. Both the type and distribution of pyrolysates among primary HULIS were comparable to those in atmospheric HULIS. This indicates that primary HULIS from combustion processes are important contributors to atmospheric HULIS. Some distinct differences were also observed. The aromatic compounds, including lignin derivatives and aromatic acid methyl ester, were the major pyrolysates (53.0%-84.9%) in all HULIS fractions, suggesting that primary HULIS significantly contributed aromatic structures to atmospheric HULIS. In addition, primary HULIS from biomass burning (BB) contained a relatively high abundance of lignin and polysaccharide derivatives, which is consistent with the large amounts of lignin and cellulose structures contained in biomass materials. Aliphatic acid methyl ester and benzyl methyl ether were prominent pyrolysates in atmospheric HULIS. Moreover, some molecular markers of specific sources were obtained from the thermochemolysis of primary and atmospheric HULIS. For example, polysaccharide derivatives, pyridine and pyrrole derivatives, and lignin derivatives can be used as tracers of fresh HULIS emitted from BB. Diterpenoid derivatives are important markers of HULIS from pine wood combustion sources. Finally, the differences in pyrolysate types and the distributions between primary and atmospheric HULIS suggested that the primary HULIS would undergo many atmospheric processes to reconstruct the macromolecular organic matter in atmospheric aerosols.

Orbital Observations of Dust Lofted by Daytime Convective Turbulence

NASA Astrophysics Data System (ADS)

Fenton, Lori; Reiss, Dennis; Lemmon, Mark; Marticorena, Béatrice; Lewis, Stephen; Cantor, Bruce

2016-11-01

Over the past several decades, orbital observations of lofted dust have revealed the importance of mineral aerosols as a climate forcing mechanism on both Earth and Mars. Increasingly detailed and diverse data sets have provided an ever-improving understanding of dust sources, transport pathways, and sinks on both planets, but the role of dust in modulating atmospheric processes is complex and not always well understood. We present a review of orbital observations of entrained dust on Earth and Mars, particularly that produced by the dust-laden structures produced by daytime convective turbulence called "dust devils". On Earth, dust devils are thought to contribute only a small fraction of the atmospheric dust budget; accordingly, there are not yet any published accounts of their occurrence from orbit. In contrast, dust devils on Mars are thought to account for several tens of percent of the planet's atmospheric dust budget; the literature regarding martian dust devils is quite rich. Because terrestrial dust devils may temporarily contribute significantly to local dust loading and lowered air quality, we suggest that martian dust devil studies may inform future studies of convectively-lofted dust on Earth.

Isotopic apportionment of atmospheric and sewage nitrogen sources in two Connecticut rivers.

PubMed

Anisfeld, Shimon C; Barnes, Rebecca T; Altabet, Mark A; Wu, Taixing

2007-09-15

We used the dual isotope approach to identify sources of nitrate (NO3-) to two mixed land-use watersheds draining to Long Island Sound. In contrastto previous work, we found that sewage effluent NO3- was not consistently enriched in 15N. However, these effluents followed a characteristic denitrification line in delta15N-delta18O space, which could be used as a source signature. We used this signature, together with those of atmospheric deposition and microbial nitrification, to calculate ranges of possible contributions from each of these sources. These estimates are unaffected by any denitrification that may have taken place in soils or streams. Our estimates for atmospheric nitrogen only include unprocessed atmospheric deposition, i.e., NO3-that is not taken up in watershed soils before being delivered to rivers. Using this method, the contribution of atmospheric NO3- could be assessed with good precision and was found to be very low at all our sampling sites during baseflow. During a moderate storm event, atmospheric deposition contributed up to approximately 50% of stream NO3-, depending on the site, with the sites that experienced more stormflow showing a greater contribution of atmospheric NO3-. Our estimates of sewage contribution generally had too large a range to be useful.

Overview of the LADEE Ultraviolet-visible Spectrometer: Design, Performance and Planned Operations

NASA Technical Reports Server (NTRS)

Colaprete, A.; Elphic, R. C.; Landis, D.; Karcz, J.; Osetinsky, L.; Shirley, M.; Vargo, K.; Wooden, D.

2013-01-01

The Lunar Atmosphere and Dust Environment Explorer (LADEE) is an orbital lunar science mission currently under development to address the goals of the 2003 National Research Council decadal survey, the Lunar Exploration Analysis Group Roadmap, and the "Scientific Context for Exploration of the Moon" (SCEM) report, and has been recommended for execution by the 2011 Planetary Missions Decadal Survey. The mission s focus is to study the pristine state of the lunar atmosphere and dust environment prior to possible lunar exploration activities by countries, including the United States, China, India, and Japan, among others. Activity on the lunar surface has the potential of altering the tenuous lunar atmosphere, but changing the type and concentration of gases in the atmosphere. Before these activities occur it is important to make measurements of the current lunar atmosphere in its unmodified state. LADEE will determine the composition of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions. It will monitor variations in known gases, such as sodium, potassium, argon and helium, and will search for other, as-yet-undetected gases of both lunar and extra-lunar origin. LADEE will also determine whether dust is present in the lunar exosphere, and reveal the processes that contribute to its sources and variability. Launch is planned for August, 2013.

The Measurement and modeling of the contribution of ...

EPA Pesticide Factsheets

In North America, ammonia (NH3) is increasingly being recognized not only for its role in atmospheric aerosol formation but also as an important component of atmospheric nitrogen deposition. This has been driven by the evolution of policies to protect ecosystems from nitrogen over-enrichment, an expansion of research underpinning these policy efforts, and technological advances in measurement and modeling tools applied to these research needs. Ammonia measurements from satellites, nitrogen focused field campaigns, and the National Atmospheric Deposition Program’s Ammonia Monitoring Network (AMoN) have advanced understanding of the processes controlling NH3 air-surface exchange and the spatio-temporal behavior of NH3 in the atmosphere. These datasets have subsequently lead to improvements in NH3 air-surface exchange models and therefore more accurate estimates of NH3 deposition. From a process standpoint, NH3 differs from other nitrogen compounds such as nitric acid in that NH3 is exchanged bi-directionally between the surface and atmosphere as regulated by a “compensation point”. Because natural surfaces may be sources or sinks of atmospheric NH3, and may alternate between emission and deposition on a timescale as short as hours, the deposition velocity concept does not accurately describe NH3 air surface exchange. Instead, a more mechanistic treatment of the nitrogen status and acidity of the surface must be employed, typically as a bi-directional fr

Plutonium in the atmosphere: A global perspective.

PubMed

Thakur, P; Khaing, H; Salminen-Paatero, S

2017-09-01

A number of potential source terms have contributed plutonium isotopes to the atmosphere. The atmospheric nuclear weapon tests conducted between 1945 and 1980 and the re-entry of the burned SNAP-9A satellite in 1964, respectively. It is generally believed that current levels of plutonium in the stratosphere are negligible and compared with the levels generally found at surface-level air. In this study, the time trend analysis and long-term behavior of plutonium isotopes ( 239+240 Pu and 238 Pu) in the atmosphere were assessed using historical data collected by various national and international monitoring networks since 1960s. An analysis of historical data indicates that 239+240 Pu concentration post-1984 is still frequently detectable, whereas 238 Pu is detected infrequently. Furthermore, the seasonal and time-trend variation of plutonium concentration in surface air followed the stratospheric trends until the early 1980s. After the last Chinese test of 1980, the plutonium concentrations in surface air dropped to the current levels, suggesting that the observed concentrations post-1984 have not been under stratospheric control, but rather reflect the environmental processes such as resuspension. Recent plutonium atmospheric air concentrations data show that besides resuspension, other environmental processes such as global dust storms and biomass burning/wildfire also play an important role in redistributing plutonium in the atmosphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

Remote sensing of the ocean contributions from ultraviolet to near-infrared using the shortwave infrared bands: simulations.

PubMed

Wang, Menghua

2007-03-20

In the remote sensing of the ocean near-surface properties, it is essential to derive accurate water-leaving radiance spectra through the process of the atmospheric correction. The atmospheric correction algorithm for Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS) uses two near-infrared (NIR) bands at 765 and 865 nm (748 and 869 nm for MODIS) for retrieval of aerosol properties with assumption of the black ocean at the NIR wavelengths. Modifications are implemented to account for some of the NIR ocean contributions for the productive but not very turbid waters. For turbid waters in the coastal regions, however, the ocean could have significant contributions in the NIR, leading to significant errors in the satellite-derived ocean water-leaving radiances. For the shortwave infrared (SWIR) wavelengths (approximately > 1000 nm), water has significantly larger absorption than those for the NIR bands. Thus the black ocean assumption at the SWIR bands is generally valid for turbid waters. In addition, for future sensors, it is also useful to include the UV bands to better quantify the ocean organic and inorganic materials, as well as for help in atmospheric correction. Simulations are carried out to evaluate the performance of atmospheric correction for nonabsorbing and weakly absorbing aerosols using the NIR bands and various combinations of the SWIR bands for deriving the water-leaving radiances at the UV (340 nm) and visible wavelengths. Simulations show that atmospheric correction using the SWIR bands can generally produce results comparable to atmospheric correction using the NIR bands. In particular, the water-leaving radiance at the UV band (340 nm) can also be derived accurately. The results from a sensitivity study for the required sensor noise equivalent reflectance, (NE Delta rho), [or the signal-to-noise ratio (SNR)] for the NIR and SWIR bands are provided and discussed.

Reducing Uncertainty in Chemistry Climate Model Predictions of Stratospheric Ozone

NASA Technical Reports Server (NTRS)

Douglass, A. R.; Strahan, S. E.; Oman, L. D.; Stolarski, R. S.

2014-01-01

Chemistry climate models (CCMs) are used to predict the future evolution of stratospheric ozone as ozone-depleting substances decrease and greenhouse gases increase, cooling the stratosphere. CCM predictions exhibit many common features, but also a broad range of values for quantities such as year of ozone-return-to-1980 and global ozone level at the end of the 21st century. Multiple linear regression is applied to each of 14 CCMs to separate ozone response to chlorine change from that due to climate change. We show that the sensitivity of lower atmosphere ozone to chlorine change deltaO3/deltaCly is a near linear function of partitioning of total inorganic chlorine (Cly) into its reservoirs; both Cly and its partitioning are controlled by lower atmospheric transport. CCMs with realistic transport agree with observations for chlorine reservoirs and produce similar ozone responses to chlorine change. After 2035 differences in response to chlorine contribute little to the spread in CCM results as the anthropogenic contribution to Cly becomes unimportant. Differences among upper stratospheric ozone increases due to temperature decreases are explained by differences in ozone sensitivity to temperature change deltaO3/deltaT due to different contributions from various ozone loss processes, each with their own temperature dependence. In the lower atmosphere, tropical ozone decreases caused by a predicted speed-up in the Brewer-Dobson circulation may or may not be balanced by middle and high latitude increases, contributing most to the spread in late 21st century predictions.

Maximum Drawdown of Atmospheric CO2 due to Biological Uptake in the Ocean and the Ocean Temperature Effect

NASA Astrophysics Data System (ADS)

Odalen, M.; Nycander, J.; Oliver, K. I. C.; Nilsson, J.; Brodeau, L.; Ridgwell, A.

2016-02-01

During glacials, atmospheric CO2 is significantly lowered; the decrease is about 1/3 or 90 ppm during the last four glacial cycles. Since the ocean reservoir of carbon, and hence the ocean capacity for storing carbon, is substantially larger than the atmospheric and terrestrial counterparts, it is likely that this lowering was caused by ocean processes, drawing the CO2 into the deep ocean. The Southern Ocean circulation and biological efficiency are widely accepted as having played an important part in this CO2 drawdown. However, the relative effects of different processes contributing to this oceanic uptake have not yet been well constrained. In this work, we focus on better constraining two of these processes; 1) the effect of increased efficiency of the biological carbon uptake, and 2) the effect of changes in global mean ocean temperature on the abiotic ocean-atmosphere CO2 equilibrium. By performing ensemble runs using an Earth System Model of Intermediate Complexity (EMIC) we examine the changes in atmospheric pCO2 achieved by 100% nutrient utilization efficiency of biology. The simulations display different ocean circulation patterns and hence different global ocean mean temperatures. By restoring the atmospheric pCO2 to a target value during the spin-up phase, the total carbon content differs between each of the ensemble members. The difference is due to circulation having direct effects on biology, but also on global ocean mean temperature, changing the solubility of CO2. This study reveals the relative importance of of the processes 1 and 2 (mentioned above) for atmospheric pCO2 in a changed climate. The results of this study also show that a difference in carbon content after spin-up can have a significant effect on the drawdown potential of a maximised biological efficiency. Thus, the choice of spin-up characteristics in a model study of climate change CO2 dynamics may significantly affect the outcome of the study.

Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid

PubMed Central

Donaldson, Melissa A.; Bish, David L.; Raff, Jonathan D.

2014-01-01

Nitrous acid (HONO) is an important hydroxyl (OH) radical source that is formed on both ground and aerosol surfaces in the well-mixed boundary layer. Recent studies report the release of HONO from nonacidic soils, although it is unclear how soil that is more basic than the pKa of HONO (∼3) is capable of protonating soil nitrite to serve as an atmospheric HONO source. Here, we used a coated-wall flow tube and chemical ionization mass spectrometry (CIMS) to study the pH dependence of HONO uptake onto agricultural soil and model substrates under atmospherically relevant conditions (1 atm and 30% relative humidity). Experiments measuring the evolution of HONO from pH-adjusted surfaces treated with nitrite and potentiometric titrations of the substrates show, to our knowledge for the first time, that surface acidity rather than bulk aqueous pH determines HONO uptake and desorption efficiency on soil, in a process controlled by amphoteric aluminum and iron (hydr)oxides present. The results have important implications for predicting when soil nitrite, whether microbially derived or atmospherically deposited, will act as a net source or sink of atmospheric HONO. This process represents an unrecognized mechanism of HONO release from soil that will contribute to HONO emissions throughout the day. PMID:25512517

Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid.

PubMed

Donaldson, Melissa A; Bish, David L; Raff, Jonathan D

2014-12-30

Nitrous acid (HONO) is an important hydroxyl (OH) radical source that is formed on both ground and aerosol surfaces in the well-mixed boundary layer. Recent studies report the release of HONO from nonacidic soils, although it is unclear how soil that is more basic than the pKa of HONO (∼ 3) is capable of protonating soil nitrite to serve as an atmospheric HONO source. Here, we used a coated-wall flow tube and chemical ionization mass spectrometry (CIMS) to study the pH dependence of HONO uptake onto agricultural soil and model substrates under atmospherically relevant conditions (1 atm and 30% relative humidity). Experiments measuring the evolution of HONO from pH-adjusted surfaces treated with nitrite and potentiometric titrations of the substrates show, to our knowledge for the first time, that surface acidity rather than bulk aqueous pH determines HONO uptake and desorption efficiency on soil, in a process controlled by amphoteric aluminum and iron (hydr)oxides present. The results have important implications for predicting when soil nitrite, whether microbially derived or atmospherically deposited, will act as a net source or sink of atmospheric HONO. This process represents an unrecognized mechanism of HONO release from soil that will contribute to HONO emissions throughout the day.

Development of a Remote Sensing Small Satellite for Temperature Sounding in the Mesosphere/Lower Thermosphere by Measurement of the Oxygen Atmospheric Band Emission

NASA Astrophysics Data System (ADS)

Deiml, Michael; Kaufmann, Martin

2017-04-01

Coupling processes initiated by gravity waves in the middle atmosphere have increasing importance for the modeling of the climate system and represent one of the larger uncertainties in this field. To support new modeling efforts spatially resolved measurements of wave fields are very beneficial. This contribution proposes a new small satellite mission based on a three unit CubeSat form factor to observe the Oxygen Atmospheric Band emission around 762 nm for temperature derivation in a limb sounding configuration to characterize gravity waves. The satellite instrument resolves individual rotational lines whose intensities follow a Boltzmann law allowing for the derivation of temperature from the relative structure of these lines. The employed Spatial Heterodyne Spectrometer is characterized by its high throughput at a small form factor, allowing to perform scientific remote sensing measurements within a small satellite during day and night. The spectrometer consists of a thermally stabilized solid block and has no moving parts, which increases its reliability in orbit while allowing high precision measurements within a small volume. The instrument is verified in its precursor mission, the Atmospheric Heterodyne Interferometer Test (AtmoHIT), within the REXUS/BEXUS ballistic rocket flight campaign. The description of the flight campaign and the results thereof conclude this contribution.

Model depiction of the atmospheric flows of radioactive cesium emitted from the Fukushima Daiichi Nuclear Power Station accident

NASA Astrophysics Data System (ADS)

Nakajima, Teruyuki; Misawa, Shota; Morino, Yu; Tsuruta, Haruo; Goto, Daisuke; Uchida, Junya; Takemura, Toshihiko; Ohara, Toshimasa; Oura, Yasuji; Ebihara, Mitsuru; Satoh, Masaki

2017-12-01

In this study, a new method is proposed for the depiction of the atmospheric transportation of the 137Cs emitted from the Fukushima Daiichi Nuclear Power Station accident. This method employs a combination of the results of two aerosol model ensembles and the hourly observed atmospheric 137Cs concentration at surface level during 14-23 March 2011 at 90 sites in the suspended particulate matter monitoring network. The new method elucidates accurate transport routes and the distribution of the surface-level atmospheric 137Cs relevant to eight plume events that were previously identified. The model ensemble simulates the main features of the observed distribution of surface-level atmospheric 137Cs. However, significant differences were found in some cases, and this suggests the need to improve the modeling of the emission scenario, plume height, wet deposition process, and plume propagation in the Abukuma Mountain region. The contributions of these error sources differ in the early and dissipating phases of each event, depending on the meteorological conditions.

Atmospheric CO2 capture by algae: Negative carbon dioxide emission path.

PubMed

Moreira, Diana; Pires, José C M

2016-09-01

Carbon dioxide is one of the most important greenhouse gas, which concentration increase in the atmosphere is associated to climate change and global warming. Besides CO2 capture in large emission point sources, the capture of this pollutant from atmosphere may be required due to significant contribution of diffuse sources. The technologies that remove CO2 from atmosphere (creating a negative balance of CO2) are called negative emission technologies. Bioenergy with Carbon Capture and Storage may play an important role for CO2 mitigation. It represents the combination of bioenergy production and carbon capture and storage, keeping carbon dioxide in geological reservoirs. Algae have a high potential as the source of biomass, as they present high photosynthetic efficiencies and high biomass yields. Their biomass has a wide range of applications, which can improve the economic viability of the process. Thus, this paper aims to assess the atmospheric CO2 capture by algal cultures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combustion Processes in the Aerospace Environment

NASA Technical Reports Server (NTRS)

Huggett, Clayton

1969-01-01

The aerospace environment introduces new and enhanced fire hazards because the special atmosphere employed may increase the frequency and intensity of fires, because the confinement associated with aerospace systems adversely affects the dynamics of fire development and control, and because the hostile external environments limit fire control and rescue operations. Oxygen enriched atmospheres contribute to the fire hazard in aerospace systems by extending the list of combustible fuels, increasing the probability of ignition, and increasing the rates of fire spread and energy release. A system for classifying atmospheres according to the degree of fire hazard, based on the heat capacity of the atmosphere per mole of oxygen, is suggested. A brief exploration of the dynamics of chamber fires shows that such fires will exhibit an exponential growth rate and may grow to dangerous size in a very short time. Relatively small quantities of fuel and oxygen can produce a catastrophic fire in a closed chamber.

Refraction effects on the Galileo probe telemetry carrier frequency

NASA Technical Reports Server (NTRS)

Atkinson, D. H.; Spilker, T. R.

1991-01-01

As the Galileo probe relay radio link (RRL) signal propagates outward through the Jovian atmosphere, the atmosphere will manifest itself in two ways. First, the geometric path length of the signal is increased, resulting in a small change of the RRL signal departure angle from the proble (transmitter). Secondly, the velocity of the signal is decreased. For a spherical, static atmosphere with a known profile of refractivity versus altitude the effects of refraction on the RRL frequency can be found using a variation of standard ray-tracing techniques, whereby the ray departure angle is found by an iterative process. From the dispersive characteristics of a mixture of hydrogen and helium with trace amounts of methane and ammonia a simple model of the Jovian atmosphere is constructed assuming spherical symmetry and uniform mixing. The contribution to the RRL Doppler frequency arising from refraction is calculated, and its effect on the Doppler wind measurements is discussed.

THE DEFINITION AND INTERPRETATION OF TERRESTRIAL ENVIRONMENT DESIGN INPUTS FOR VEHICLE DESIGN CONSIDERATIONS

NASA Technical Reports Server (NTRS)

Johnson, Dale L.; Keller, Vernon W.; Vaughan, William W.

2005-01-01

The description and interpretation of the terrestrial environment (0-90 km altitude) is an important driver of aerospace vehicle structural, control, and thermal system design. NASA is currently in the process of reviewing the meteorological information acquired over the past decade and producing an update to the 1993 Terrestrial Environment Guidelines for Aerospace Vehicle Design and Development handbook. This paper addresses the contents of this updated handbook, with special emphasis on new material being included in the areas of atmospheric thermodynamic models, wind dynamics, atmospheric composition, atmospheric electricity, cloud phenomena, atmospheric extremes, sea state, etc. In addition, the respective engineering design elements will be discussed relative to the importance and influence of terrestrial environment inputs that require consideration and interpretation for design applications. Specific lessons learned that have contributed to the advancements made in the acquisition, interpretation, application and awareness of terrestrial environment inputs for aerospace engineering applications are discussed.

Experimental and theoretical studies of near-ground acoustic radiation propagation in the atmosphere

NASA Astrophysics Data System (ADS)

Belov, Vladimir V.; Burkatovskaya, Yuliya B.; Krasnenko, Nikolai P.; Rakov, Aleksandr S.; Rakov, Denis S.; Shamanaeva, Liudmila G.

2017-11-01

Results of experimental and theoretical studies of the process of near-ground propagation of monochromatic acoustic radiation on atmospheric paths from a source to a receiver taking into account the contribution of multiple scattering on fluctuations of atmospheric temperature and wind velocity, refraction of sound on the wind velocity and temperature gradients, and its reflection by the underlying surface for different models of the atmosphere depending the sound frequency, coefficient of reflection from the underlying surface, propagation distance, and source and receiver altitudes are presented. Calculations were performed by the Monte Carlo method using the local estimation algorithm by the computer program developed by the authors. Results of experimental investigations under controllable conditions are compared with theoretical estimates and results of analytical calculations for the Delany-Bazley impedance model. Satisfactory agreement of the data obtained confirms the correctness of the suggested computer program.

Ionization in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, R. L.; Helling, Ch.; Hodosán, G.

2014-03-20

Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g., by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionization state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to DRIFT-PHOENIX model atmosphere results to model the discharge's propagation downward (as lightning)more » and upward (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g., by increase of temperature or electron number) is larger in a brown dwarf atmosphere (10{sup 8}-10{sup 10} m{sup 3}) than in a giant gas planet (10{sup 4}-10{sup 6} m{sup 3}). Our results suggest that the total dissipated energy in one event is <10{sup 12} J for all models of initial solar metallicity. First attempts to show the influence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH{sub 2} at the expense of CO and CH{sub 4}. Dust-forming molecules are destroyed and the cloud particle properties are frozen in unless enough time is available for complete evaporation. We summarize instruments potentially suitable to observe lightning on extrasolar objects.« less

On magnetohydrodynamic thermal instabilities in magnetic flux tubes. [in plane parallel stellar atmosphere in LTE and hydrostatic equilibrium

NASA Technical Reports Server (NTRS)

Massaglia, S.; Ferrari, A.; Bodo, G.; Kalkofen, W.; Rosner, R.

1985-01-01

The stability of current-driven filamentary modes in magnetic flux tubes embedded in a plane-parallel atmosphere in LTE and in hydrostatic equilibrium is discussed. Within the tube, energy transport by radiation only is considered. The dominant contribution to the opacity is due to H- ions and H atoms (in the Paschen continuum). A region in the parameter space of the equilibrium configuration in which the instability is effective is delimited, and the relevance of this process for the formation of structured coronae in late-type stars and accretion disks is discussed.

The Howard University Program in Atmospheric Sciences: A Program Exemplifying Diversity and Excellence

NASA Astrophysics Data System (ADS)

Morria, V. R.; Demoz, B.; Joseph, E.

2017-12-01

The Howard University Graduate Program in Atmospheric Sciences (HUPAS) is the first advanced degree program in the atmospheric sciences instituted at a Historically Black College/University (HBCU) or at a Minority-Serving Institution (MSI). MSI in this context refers to academic institutions whose histories are grounded in serving minority students from their inception, rather than institutions whose student body demographics have evolved along with the "browning of America" and now meet recent Federal criteria for "minority-serving". HUPAS began in 1996 when initiatives within the Howard University Graduate School overlapped with the motivations of investigators within a NASA-funded University research center for starting a sustainable interdisciplinary program. After twenty years, the results have been the production of greater institutional depth and breadth of research in the geosciences and significant production of minority scientists contributing to the atmospheric sciences enterprise in various sectors. This presentation will highlight the development of the Howard University graduate program in atmospheric sciences, its impact on the national statistics for the production of underrepresented minority (URM) advanced degree holders in the atmospheric sciences, and some of the program's contributions to the diversity in geosciences and the National pipeline of talent from underrepresented groups. Over the past decade, Howard University is leading producer of African American and Hispanic female doctorates in atmospheric sciences - producing nearly half of all degree holders in the Nation. Specific examples of successful partnerships between this program and federal funding agencies such as NASA and NOAA which have been critical in the development process will also be highlighted. Finally, some of the student recruitment and retention strategies that have enabled the success of this program and statistics of student graduation will also be shared and challenges to continued progress in diversifying the atmospehric sciences will be discussed.

Transmission of atmospherically derived trace elements through an undeveloped, forested Maryland watershed

USGS Publications Warehouse

Scudlark, J.R.; Rice, Karen C.; Conko, Kathryn M.; Bricker, Owen P.; Church, T.M.

2005-01-01

The transmission of atmospherically derived trace elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) was evaluated in a small, undeveloped, forested watershed located in north-central Maryland. Atmospheric input was determined for wet-only and vegetative throughfall components. Annual throughfall fluxes were significantly enriched over incident precipitation for most elements, although some elements exhibited evidence of canopy release (Mn) or preferential uptake (As, Cr, and Se). Stream export was gauged based on systematic sampling under varied flow regimes. Particle loading appears to contribute significantly to watershed export (> 10%) for only As, Pb, and Fe, and then only during large precipitation/runoff events. The degree of watershed transmission for each trace element was evaluated based on a comparison of total, net atmospheric input (throughfall) to stream export over an annual hydrologic cycle. This comparison indicates that the atmospheric input of some elements (Al, Cd, Ni, Zn) is effectively transmitted through the watershed, but other elements (Pb, As, Se, Fe, Cr, Cu) appear to be strongly sequestered, in the respective orders noted. Results suggest that precipitation and subsequent soil pH are the primary factors that determine the mobility of sequestered trace element phases.To further resolve primary atmospheric and secondary weathering components, the geochemical model NETPATH was applied. Results indicate that minerals dissolved include chlorite, plagioclase feldspar, epidote, and potassium feldspar; phases formed were kaolinite, pyrite, and silica. The model also indicates that weathering processes contribute negligible amounts of trace elements to stream export, indicative of the unreactive orthoquartzite bedrock lithology underlying the watershed. Thus, the stream export of trace elements primarily reflects atmospheric deposition to the local watershed.

Effects of sintering atmosphere on the physical and mechanical properties of modified BOF slag glass

NASA Astrophysics Data System (ADS)

Dai, Wen-bin; Li, Yu; Cang, Da-qiang; Zhou, Yuan-yuan; Fan, Yong

2014-05-01

This study proposes an efficient way to utilize all the chemical components of the basic oxygen furnace (BOF) slag to prepare high value-added glass-ceramics. A molten modified BOF slag was converted from the melting BOF slag by reducing it and separating out iron component in it, and the modified BOF slag was then quenched in water to form glasses with different basicities. The glasses were subsequently sintered in the temperature range of 600-1000°C in air or nitrogen atmosphere for 1 h. The effects of different atmospheres on the physical and mechanical properties of sintered samples were studied by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and by conducting experiment on evaluating the sintering shrinkage, water absorption and bulk density. It is found that the kinetics of the sintering process is significantly affected by sintering atmosphere. In particular, compared with sintering in air atmosphere, sintering in N2 atmosphere promotes the synergistic growth of pyroxene and melilite crystalline phases, which can contribute to better mechanical properties and denser microstructure.

Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorski, Galen; Strong, Courtenay; Good, Stephen P.

Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Some effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. Furthermore, we show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration ofmore » water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. These findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.« less

Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

DOE PAGES

Gorski, Galen; Strong, Courtenay; Good, Stephen P.; ...

2015-03-02

Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Some effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. Furthermore, we show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration ofmore » water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. These findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.« less

Neutral polyfluoroalkyl substances in the atmosphere over the northern South China Sea.

PubMed

Lai, Senchao; Song, Junwei; Song, Tianli; Huang, Zhijiong; Zhang, Yingyi; Zhao, Yan; Liu, Guicheng; Zheng, Junyu; Mi, Wenying; Tang, Jianhui; Zou, Shichun; Ebinghaus, Ralf; Xie, Zhiyong

2016-07-01

Neutral Polyfluoroalkyl substances (PFASs) in the atmosphere were measured during a cruise campaign over the northern South China Sea (SCS) from September to October 2013. Four groups of PFASs, i.e., fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAs), fluorooctane sulfonamides (FOSAs) and fluorooctane sulfonamidoethanols (FASEs), were detected in gas samples. FTOHs was the predominant PFAS group, accounting for 95.2-99.3% of total PFASs (ΣPFASs), while the other PFASs accounted for a small fraction of ΣPFASs. The concentrations of ΣPFASs ranged from 18.0 to 109.9 pg m(-3) with an average of 54.5 pg m(-3). The concentrations are comparable to those reported in other marine atmosphere. Higher concentrations of ΣPFASs were observed in the continental-influenced samples than those in other samples, pointing to the substantial contribution of anthropogenic sources. Long-range transport is suggested to be a major pathway for introducing gaseous PFASs into the atmosphere over the northern SCS. In order to further understand the fate of gaseous PFASs during transport, the atmospheric decay of neutral PFASs under the influence of reaction with OH radicals and atmospheric physical processes were estimated. Concentrations of 8:2 FTOH, 6:2 FTOH and MeFBSE from selected source region to the atmosphere over the SCS after long-range transport were predicted and compared with the observed concentrations. It suggests that the reaction with OH radicals may play an important role in the atmospheric decay of PFAS during long-range transport, especially for shorted-lived species. Moreover, the influence of atmospheric physical processes on the decay of PFAS should be further considered. Copyright © 2016 Elsevier Ltd. All rights reserved.

Organic matter in meteorites and comets - Possible origins

NASA Technical Reports Server (NTRS)

Anders, Edward

1991-01-01

At least six extraterrestrial environments may have contributed organic compounds to meteorites and comets: solar nebula, giant-planet subnebulae, asteroid interiors containing liquid water, carbon star atmospheres, and diffuse or dark interstellar clouds. The record in meteorites is partly obscured by pervasive reheating that transformed much of the organic matter to kerogen; nonetheless, it seems that all six formation sites contributed. For comets, the large abundance of HCHO, HCN, and unsaturated hydrocarbons suggests an interstellar component of 50 percent or more, but the contributions of various interstellar processes, and of a solar-nebula component, are hard to quantify. A research program is outlined that may help reduce these uncertainties.

A Method to Access Absolute fIPAR fo Vegetation in Spatially Complex Ecosystems

NASA Technical Reports Server (NTRS)

Wessman, Carol A.; Nel, Elizabeth M.; Bateson, C. Ann; Asner, Gregory P.

1998-01-01

Arid and semi-arid lands compose a large fraction of the earth's terrestrial vegetation, and thereby contribute significantly to global atmospheric-biospheric interactions. The thorny shrubs and small trees in these semi-arid shrub lands have counterparts throughout much of the world's tropical and subtropical zones and have captured substantial areas of the world's former grasslands. The objective of our field and remotely sensed measurements in the semi-arid shrublands of Texas is to monitor interannual variability and directional change in landscape structure, ecosystem processes and atmosphere-biosphere exchanges. To understand the role ecosystems play in controlling the composition of the atmosphere, it is necessary to quantify processes such as photosynthesis and primary production, decomposition and soil carbon storage, and trace gas exchanges. Photosynthesis is the link whereby surface-atmosphere exchanges such as the radiation balance and exchange of heat, moisture, and gas can be inferred. It also describes the efficiency of carbon dioxide exchange and is directly related to the primary production of vegetation. Our efforts in this paper focus on the indirect, quantification of photosynthesis, and thereby carbon flux and net primary production, via remote sensing and direct measurements of intercepted photosynthetically active radiation (IPAR).

The Antarctic ozone hole

NASA Technical Reports Server (NTRS)

Stolarski, Richard S.

1988-01-01

Processes that may be responsible for the thinning in the ozone layer above the South Pole are described. The chlorine catalytic cycle which destroys ozone is described, as are the major types of reactions that are believed to interfere with this cycle by forming chlorine reservoirs. The suspected contributions of polar stratospheric clouds to these processes are examined. Finally, the possibility that the ozone hole may be due more to a shift in atmospheric dynamics than to chemical destruction is addressed.

[CO2 turbulent exchange in a broadleaved Korean pine forest in Changbai Mountains].

PubMed

Wu, Jia-bing; Guan, De-xin; Sun, Xiao-min; Shi, Ting-ting; Han, Shi-jie; Jin, Chang-jie

2007-05-01

The measurement of CO2 turbulent exchange in a broadleaved Korean pine forest in Changbai Mountains by an open-path eddy covariance system showed that with near neutral atmospheric stratification, the CO2 and vertical wind components over canopy in inertial subrange followed the expected -2/3 power law, and the dominant vertical eddy scale was about 40 m. The frequency ranges of eddy contributions to CO2 fluxes were mostly within 0.01-2.0 Hz, and the eddy translated by low frequency over canopy contributed more of CO2 fluxes. The open-path eddy covariance system could satisfy the estimation of turbulent fluxes over canopy, but the CO2 fluxes between forest and atmosphere were generally underestimated at night because the increment of non turbulent processes, suggesting that the CO2 fluxes estimated under weak turbulence needed to revise correspondingly.

Microbial contributions to the Precambrian Earth

NASA Technical Reports Server (NTRS)

Margulis, L.; Bermudes, D.; Obar, R.

1986-01-01

Life has existed on Earth for approximately 3.5 billion years. For most of this time, prokaryotic communities provided the major biological forces changing the Earth. Many changes in atmospheric gas composition occurred during the Archean and Proterozoic eons as a result of microbial activity. Extant microbial communities were used to help understand the dynamics which contributed to these atmospheric changes. The microbial mat communities were characterized according to the organismic constituents. Symbiosis in microbial communities is recognized as a major force in cell evolution. Among the evolutinary enigmas investigated is the problem of the origin of the undulipodia. Undulipodial microtubules are still deployed for major cellular processes such as mitosis and meiosis. Several prokaryotes were tested for the presence of the S1-type protein, so far only spirochetes were found to possess it. The S1-type protein is being sought in cyanobacteria reported to contain microtubules.

NASA's Upper Atmosphere Research Program (UARP) and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1997-1999

NASA Technical Reports Server (NTRS)

Kurylo, M. J.; DeCola, P. L.; Kaye, J. A.

2000-01-01

Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology development, and monitoring of the Earth's upper atmosphere, with emphasis on the upper troposphere and stratosphere. This program aims at expanding our chemical and physical understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Research Division in the Office of Earth Science at NASA. Significant contributions to this effort have also been provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aero-Space Technology. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper troposphere and the stratosphere and their control on the distribution of atmospheric chemical species such as ozone; assess possible perturbations to the composition of the atmosphere caused by human activities and natural phenomena (with a specific emphasis on trace gas geographical distributions, sources, and sinks and the role of trace gases in defining the chemical composition of the upper atmosphere); understand the processes affecting the distributions of radiatively active species in the atmosphere, and the importance of chemical-radiative-dynamical feedbacks on the meteorology and climatology of the stratosphere and troposphere; and understand ozone production, loss, and recovery in an atmosphere with increasing abundances of greenhouse gases. The current report is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported under NASA UARP and ACMAP in a document entitled, Research Summaries 1997- 1999. Part 2 is entitled Present State of Knowledge of the Upper Atmosphere 1999 An Assessment Report.

Influence of the forest canopy on total and methyl mercury deposition in the boreal forest

Treesearch

E.L. Witt; R.K. Kolka; E.A. Nater; T.R. Wickman

2009-01-01

Atmospheric mercury deposition by wet and dry processes contributes mercury to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to boreal forests were identified in this study. Throughfall and open canopy precipitation samples were collected in 2005 and 2006 using passive precipitation collectors from pristine sites located across...

Hydrological and Climate Controls on Hyporheic Contributions to River Net Ecosystem Productivity

NASA Astrophysics Data System (ADS)

Newcomer, M. E.; Hubbard, S. S.; Fleckenstein, J. H.; Maier, U.; Schmidt, C.; Laube, G.; Chen, N.; Ulrich, C.; Dwivedi, D.; Steefel, C. I.; Rubin, Y.

2016-12-01

Hyporheic zone contributions to river net ecosystem productivity (NEP) can represent a substantial source or sink for organic and inorganic carbon (C). Hyporheic zone processes are estimated to vary with network location as a function of river-aquifer interactions as well as with climatic factors supporting riverbed gross primary productivity (GPP) and ecosystem respiration. Even though hyporheic zone NEP is hypothesized to be a significant budgetary component to river-aquifer biogeochemical cycling, models of river NEP often parameterize hyporheic zone contributions as a space-time constant input of CO2 to rivers, leading to overestimation of hyporheic zone NEP and underestimation of C storage. This assumption is problematic during the summer growing season, when GPP is largest and C is stored in surface and subsurface biomass. We investigated the dynamic role of hyporheic zone NEP using the MIN3P flow and reactive transport model with surface water GPP and ecosystem respiration simulated as a function of light, depth, temperature, pH, and atmospheric CO2. We simulated hyporheic zone NEP for low-order and high-order streams, which collectively represent a range of characteristic flow paths and subsurface residence times. Downscaled climate predictions of temperature and atmospheric CO2 representing carbon emission futures were used to force the models and to compare future and current hyporheic zone NEP. Our results show that river-aquifer flow conditions determine the relative role of the river as either a store or sink of C through direct contributions of O2 and dissolved organic content from river GPP. Modeled results show that high discharge, high order rivers are net stores of CO2 from the atmosphere; however this is dependent on perturbation events that allow stored C from summer GPP to be released (i.e. rising water tables during winter storms). Lacking a perturbation event, C remains in pore-water storage as dissolved CO2 and biomass. Conversely, low-discharge mountainous streams with continuous hyporheic zone flow represent a net source of CO2, with future temperature rises stimulating additional heterotrophic activity. Our work contributes to a better understanding of how river and hyporheic zone processes significantly influence biogeochemical cycling under changing climate conditions.

Mercury deposition and re-emission pathways in boreal forest soils investigated with Hg isotope signatures.

PubMed

Jiskra, Martin; Wiederhold, Jan G; Skyllberg, Ulf; Kronberg, Rose-Marie; Hajdas, Irka; Kretzschmar, Ruben

2015-06-16

Soils comprise the largest terrestrial mercury (Hg) pool in exchange with the atmosphere. To predict how anthropogenic emissions affect global Hg cycling and eventually human Hg exposure, it is crucial to understand Hg deposition and re-emission of legacy Hg from soils. However, assessing Hg deposition and re-emission pathways remains difficult because of an insufficient understanding of the governing processes. We measured Hg stable isotope signatures of radiocarbon-dated boreal forest soils and modeled atmospheric Hg deposition and re-emission pathways and fluxes using a combined source and process tracing approach. Our results suggest that Hg in the soils was dominantly derived from deposition of litter (∼90% on average). The remaining fraction was attributed to precipitation-derived Hg, which showed increasing contributions in older, deeper soil horizons (up to 27%) indicative of an accumulation over decades. We provide evidence for significant Hg re-emission from organic soil horizons most likely caused by nonphotochemical abiotic reduction by natural organic matter, a process previously not observed unambiguously in nature. Our data suggest that Histosols (peat soils), which exhibit at least seasonally water-saturated conditions, have re-emitted up to one-third of previously deposited Hg back to the atmosphere. Re-emission of legacy Hg following reduction by natural organic matter may therefore be an important pathway to be considered in global models, further supporting the need for a process-based assessment of land/atmosphere Hg exchange.

Contribution of natural terrestrial sources to the atmospheric chloroform budget

NASA Astrophysics Data System (ADS)

Rhew, R. C.; Abel, T.; Pan, D.; Whelan, M.

2008-12-01

Chloroform (trichloromethane, CHCl3) is the second largest carrier of natural chlorine in the troposphere after methyl chloride, contributing to the reactive chlorine burden in the troposphere and to ozone destruction in the stratosphere. Our understanding of the biogeochemical cycling of atmospheric CHCl3 has undergone major adjustments recently, including the quantification of the total atmospheric burden of this compound, the estimated global source and sink strengths, and the relative contributions of anthropogenic versus natural contributions. Numerous natural terrestrial sources have been identified, including temperate peatlands, Arctic tundra, termite mounds, salt marshes, grasslands, forests and woodlands. However, the wide variability of fluxes within each ecosystem has complicated efforts to quantify the overall terrestrial source. In addition, the environmental and biogeochemical controls remain largely unknown. We shall present a comparison of recent CHCl3 flux measurements that cover a range of biome types and climatic conditions. To address within-biome variability, flux measurements from the Arctic tundra and temperate grasslands will be compared to common environmental parameters (e.g., temperature, soil moisture, solar insolation) and other trace gas fluxes (CH3Cl, CH4, CCl4). The generally poor correlations demonstrate that the variability of CHCl3 emissions may be affected by site-specific parameters that are not currently measured or by drastic changes in hydrologic conditions. Similar patterns are observed in laboratory incubations of tundra peat and grassland soils. We explore the possibility that the humification of plant material, which has been shown to produce organochlorine compounds through the chlorination of organic matter, may contribute to CHCl3 emissions. If this link exists, then CHCl3 production could potentially act as a proxy for organic matter degradation and carbon sequestration, essential biogeochemical and ecosystem processes.

An End-to-End simulator for the development of atmospheric corrections and temperature - emissivity separation algorithms in the TIR spectral domain

NASA Astrophysics Data System (ADS)

Rock, Gilles; Fischer, Kim; Schlerf, Martin; Gerhards, Max; Udelhoven, Thomas

2017-04-01

The development and optimization of image processing algorithms requires the availability of datasets depicting every step from earth surface to the sensor's detector. The lack of ground truth data obliges to develop algorithms on simulated data. The simulation of hyperspectral remote sensing data is a useful tool for a variety of tasks such as the design of systems, the understanding of the image formation process, and the development and validation of data processing algorithms. An end-to-end simulator has been set up consisting of a forward simulator, a backward simulator and a validation module. The forward simulator derives radiance datasets based on laboratory sample spectra, applies atmospheric contributions using radiative transfer equations, and simulates the instrument response using configurable sensor models. This is followed by the backward simulation branch, consisting of an atmospheric correction (AC), a temperature and emissivity separation (TES) or a hybrid AC and TES algorithm. An independent validation module allows the comparison between input and output dataset and the benchmarking of different processing algorithms. In this study, hyperspectral thermal infrared scenes of a variety of surfaces have been simulated to analyze existing AC and TES algorithms. The ARTEMISS algorithm was optimized and benchmarked against the original implementations. The errors in TES were found to be related to incorrect water vapor retrieval. The atmospheric characterization could be optimized resulting in increasing accuracies in temperature and emissivity retrieval. Airborne datasets of different spectral resolutions were simulated from terrestrial HyperCam-LW measurements. The simulated airborne radiance spectra were subjected to atmospheric correction and TES and further used for a plant species classification study analyzing effects related to noise and mixed pixels.

Assessment of atmospheric trace metal deposition in urban environments using direct and indirect measurement methodology and contributions from wet and dry depositions

NASA Astrophysics Data System (ADS)

Omrani, Mehrazin; Ruban, Véronique; Ruban, Gwenaël; Lamprea, Katerine

2017-11-01

Bulk Atmospheric Deposition (BAD), Wet Atmospheric Deposition (WAD) and Dry Atmospheric Deposition (DAD) were all measured within an urban residential area in Nantes (France) over a 9-month period (27 February - 10 December 2014). The objectives of this study were to compare 2 methods for measuring dry and wet atmospheric depositions in the urban environment (DAD and WAD: direct method; BAD and WAD: indirect one), and to characterize as well the variations and relative contributions of these depositions. Trace metals (As, Cd, Cr, Cu, Ni, Pt and V) were used to carry out these comparison and quantification. BAD was collected with two open polyethylene containers (72 × 54 × 21 cm), while WAD was collected by means of an automated rainwater collector and DAD was determined from both air measurements (recorded by an air sampler) and 7Be deposition velocities. The comparison based on a detailed evaluation of uncertainties showed a significant difference between the direct and indirect methods. Dry and wet depositions varied widely from one month to the next. Zn and Cu were the most abundant elements in both dry and wet depositions. The mean contribution of DAD to the bulk atmospheric deposition during this 9-month study was significant for Zn, Cu and V (about 25%) as well as for Pb (approx. 60%). For this relatively unpolluted urban residential catchment, the contribution of atmospheric deposition to global load at the catchment outlet was low, between 10% and 20% for Zn, Cu, V and Pb, 25% for Cr and about 30% for Ni. For other urban sites exhibiting high atmospheric pollution however, the atmospheric contribution to the global pollution load could be much greater. An accurate and representative estimation of DAD thus proves critical.

Atmospheric Pressure Glow Discharge for Point-of-Use Water Treatment

NASA Astrophysics Data System (ADS)

Lindsay, Alexander; Byrns, Brandon; Shannon, Steven; Knappe, Detlef

2012-10-01

Treatment of biological and chemical contaminants is an area of growing global interest where atmospheric pressure plasmas can make a significant contribution. Addressing key challenges of volume processing and operational cost, a large volume 162 MHz coaxial air-plasma source has been developed.footnotetextByrns (2012) J. Phys. D: Appl. Phys. 45 (2012) 195204 Because of VHF ballasting effects, the electric discharge is maintained at a steady glow, allowing formation of critical non-equilibrium chemistry. High densities, ne = 10^11-10^12, have been recorded. The atmospheric nature of the device permits straightforward and efficient treatment of water samples. [H^+] concentrations in 150 milliliter tap water samples have been shown to increase by 10^5 after five minutes of discharge exposure. Recent literature has demonstrated that increasing acidity is strongly correlated with a solution's ability to deactivate microbial contaminants.footnotetextTraylor (2011) J. Phys. D: Appl. Phys. 44 (2011) 472001 The work presented here will explore the impact of treatment gas, system configuration, and power density on water disinfection and PFC abatement. An array of plasma diagnostics, including OES and electrical measurements, are combined with post-process water analysis, including GC-MS and QT analysis of coliform and E.coli bacteria. Development of volume processing atmospheric plasma disinfection methods offers promise for point-of-use treatments in developing areas of the world, potentially supplementing or replacing supply and weather-dependent disinfection methods.

[Study on the modeling of earth-atmosphere coupling over rugged scenes for hyperspectral remote sensing].

PubMed

Zhao, Hui-Jie; Jiang, Cheng; Jia, Guo-Rui

2014-01-01

Adjacency effects may introduce errors in the quantitative applications of hyperspectral remote sensing, of which the significant item is the earth-atmosphere coupling radiance. However, the surrounding relief and shadow induce strong changes in hyperspectral images acquired from rugged terrain, which is not accurate to describe the spectral characteristics. Furthermore, the radiative coupling process between the earth and the atmosphere is more complex over the rugged scenes. In order to meet the requirements of real-time processing in data simulation, an equivalent reflectance of background was developed by taking into account the topography and the geometry between surroundings and targets based on the radiative transfer process. The contributions of the coupling to the signal at sensor level were then evaluated. This approach was integrated to the sensor-level radiance simulation model and then validated through simulating a set of actual radiance data. The results show that the visual effect of simulated images is consistent with that of observed images. It was also shown that the spectral similarity is improved over rugged scenes. In addition, the model precision is maintained at the same level over flat scenes.

Gaia's breath - Global methane exhalations

USGS Publications Warehouse

Kvenvolden, K.A.; Rogers, B.W.

2005-01-01

Methane (CH4) is the most abundant organic compound in the Earth's atmosphere, where it acts as a greenhouse gas and thus has implications for global climate change. The current atmospheric CH4 budget, however, does not take into account geologically-sourced CH4 seepage. Geological sources of CH4 include natural macro- and micro-seeps, mud volcanoes, and other miscellaneous sources such as gas hydrates, magmatic volcanoes, geothermal regions, and mid-ocean ridges. Macro-seeps contribute ???25 Tg (teragrams) CH4/yr to the atmosphere, whereas, micro-seepage contributes perhaps 7 Tg CH4/yr. Mud volcanoes emit ???5 Tg CH4/yr, and miscellaneous sources emit ???8 Tg CH4/yr to the atmosphere. Thus, the total contribution to the atmosphere from geological sources is estimated to be 45 Tg CH4/yr, which is significant to the atmospheric organic carbon cycle and should be included in any global inventory of atmospheric CH4. We argue that the atmospheric CH4 global inventory of the Interplanetary Panel on Climate Change must be adjusted in order to incorporate geologically-sourced CH4 from naturally occurring seepage.

Nitrogen isotopes as indicators of streamflow generation processes in a headwater forested catchment: Focusing on atmospheric NO3- contribution using δ 18O signature

NASA Astrophysics Data System (ADS)

Ohte, N.; Sebestyen, S. D.; Doctor, D. H.; Wankel, S. D.; Shanley, J. B.; Kendall, C.; Boyer, E. W.

2003-12-01

To quantify the contributions of atmospheric nitrogen deposition and mechanisms of nitrate discharge to stream, nitrogen chemistry and isotopes (δ 15N and δ 18O of NO3-) of streamwater were studied as part of an ongoing study of nutrient dynamics at the Sleepers River Research Watershed in Vermont, USA. We employed novel analytical procedures for high throughput of NO3- isotopic measurements. The denitrifier method for measurement of δ 15N and δ 18O of NO3- requires a smaller volume of water samples than previously applied methods, thus it enables fine resolution analysis of isotopes for stream, well, and soil water samples. Samples were collected throughout the spring 2003 snowmelt. Snowmelt runoff was initiated in the middle of March and peaked at the end of the month. Then, the runoff rate decreased gradually through April and May, and responded to several storm events. The highest concentration of NO3- in the stream was observed at the beginning of snowmelt (the end of March), and thereafter it declined continuously. The temporal course of NO3- discharge process during snowmelt period was divided into four phases based on changes in the relationship between runoff rate and NO3- concentration. During the earliest phase (very low runoff rate and highest NO3- concentration) isotope signatures, especially δ 18O of NO3-, indicated higher contribution of the atmospherically derived NO3-, meaning that the direct discharge from snow pack was the dominant source of NO3- to the stream. This also suggested that streamwater consisted only of a small volume of groundwater discharge and melt water of the in-stream snow pack and/or stream-covering snow pack. The δ 15N and δ 18O isotope compositions of NO3- during the middle phase of snowmelt indicated that the contribution of the NO3- generated by nitrifiers in soil increased gradually accompanied with increase of groundwater level. These detailed descriptions in the changes of NO3- discharge during snowmelt events were enabled by the dual-isotope analysis of NO3-. The fine resolution isotope analysis of NO3- in our experiment can provide advantages for elucidating the discharge mechanisms of nitrogen in forested watersheds with high atmospheric nitrogen depositions.

Contributions of high-altitude winds and atmospheric moment of inertia to the atmospheric angular momentum-earth rotation relationship

NASA Technical Reports Server (NTRS)

Taylor, H. A., Jr.; Mayr, H. G.; Kramer, L.

1985-01-01

For many years it has been recognized that recurrent modulations occur in the time series of the earth's rotation rate or, alternatively, the change in the length of the day (Delta-LOD). Studies relating Delta-LOD to global patterns of zonal winds have confirmed that the variability of atmospheric angular momentum (M) is of sufficient magnitude to account for a large portion of the gross periodicities observed in the earth rotation. The present investigation is concerned with the importance of the contributions of the moment of inertia and high-altitude winds to the angular momentum budget. On the basis of an analysis of the various factors, it is found that within the available data, contributions of high-altitude winds and atmospheric moment of inertia reach levels detectable in the atmospheric angular momentum budget. Nevertheless, for the period December 1978 to December 1979 these contributions are not sufficient to resolve the apparent short-term discrepancies which are evident between Delta-LOD and M.

Contribution of Anthropogenic and Natural Emissions to Global CH4 Balances by Utilizing δ13C-CH4 Observations in CarbonTracker Data Assimilation System (CTDAS)

NASA Astrophysics Data System (ADS)

Kangasaho, V. E.; Tsuruta, A.; Aalto, T.; Backman, L. B.; Houweling, S.; Krol, M. C.; Peters, W.; van der Laan-Luijkx, I. T.; Lienert, S.; Joos, F.; Dlugokencky, E. J.; Michael, S.; White, J. W. C.

2017-12-01

The atmospheric burden of CH4 has more than doubled since preindustrial time. Evaluating the contribution from anthropogenic and natural emissions to the global methane budget is of great importance to better understand the significance of different sources at the global scale, and their contribution to changes in growth rate of atmospheric CH4 before and after 2006. In addition, observations of δ13C-CH4 suggest an increase in natural sources after 2006, which matches the observed increase and variation of CH4 abudance. Methane emission sources can be identified using δ13C-CH4, because different sources produce methane with process-specific isotopic signatures. This study focuses on inversion model based estimates of global anthropogenic and natural methane emission rates to evaluate the existing methane emission estimates with a new δ13C-CH4 inversion system. In situ measurements of atmospheric methane and δ13C-CH4 isotopic signature, provided by the NOAA Global Monitoring Division and the Institute of Arctic and Alpine Research, will be assimilated into the CTDAS-13C-CH4. The system uses the TM5 atmospheric transport model as an observation operator, constrained by ECMWF ERA Interim meteorological fields, and off-line TM5 chemistry fields to account for the atmospheric methane sink. LPX-Bern DYPTOP ecosystem model is used for prior natural methane emissions from wetlands, peatlands and mineral soils, GFED v4 for prior fire emissions and EDGAR v4.2 FT2010 inventory for prior anthropogenic emissions. The EDGAR antropogenic emissions are re-divided into enteric fermentation and manure management, landfills and waste water, rice, coal, oil and gas, and residential emissions, and the trend of total emissions is scaled to match optimized anthropogenic emissions from CTE-CH4. In addition to these categories, emissions from termites and oceans are included. Process specific δ13C-CH4 isotopic signatures are assigned to each emission source to estimate 13CH4 fraction in CH4 emissions. Among the priors, anthropogenic and natural emissions are optimized and others are directly imposed from the prior. A detailed emission estimates of antropogenic and natural CH4 emissions will be constructed in order to provide a more comprehensive understanding of methane emission source divisions.

Centuries of thermal sea-level rise due to anthropogenic emissions of short-lived greenhouse gases

PubMed Central

Zickfeld, Kirsten

2017-01-01

Mitigation of anthropogenic greenhouse gases with short lifetimes (order of a year to decades) can contribute to limiting warming, but less attention has been paid to their impacts on longer-term sea-level rise. We show that short-lived greenhouse gases contribute to sea-level rise through thermal expansion (TSLR) over much longer time scales than their atmospheric lifetimes. For example, at least half of the TSLR due to increases in methane is expected to remain present for more than 200 y, even if anthropogenic emissions cease altogether, despite the 10-y atmospheric lifetime of this gas. Chlorofluorocarbons and hydrochlorofluorocarbons have already been phased out under the Montreal Protocol due to concerns about ozone depletion and provide an illustration of how emission reductions avoid multiple centuries of future TSLR. We examine the “world avoided” by the Montreal Protocol by showing that if these gases had instead been eliminated in 2050, additional TSLR of up to about 14 cm would be expected in the 21st century, with continuing contributions lasting more than 500 y. Emissions of the hydrofluorocarbon substitutes in the next half-century would also contribute to centuries of future TSLR. Consideration of the time scales of reversibility of TSLR due to short-lived substances provides insights into physical processes: sea-level rise is often assumed to follow air temperature, but this assumption holds only for TSLR when temperatures are increasing. We present a more complete formulation that is accurate even when atmospheric temperatures are stable or decreasing due to reductions in short-lived gases or net radiative forcing. PMID:28069937

Centuries of thermal sea-level rise due to anthropogenic emissions of short-lived greenhouse gases.

PubMed

Zickfeld, Kirsten; Solomon, Susan; Gilford, Daniel M

2017-01-24

Mitigation of anthropogenic greenhouse gases with short lifetimes (order of a year to decades) can contribute to limiting warming, but less attention has been paid to their impacts on longer-term sea-level rise. We show that short-lived greenhouse gases contribute to sea-level rise through thermal expansion (TSLR) over much longer time scales than their atmospheric lifetimes. For example, at least half of the TSLR due to increases in methane is expected to remain present for more than 200 y, even if anthropogenic emissions cease altogether, despite the 10-y atmospheric lifetime of this gas. Chlorofluorocarbons and hydrochlorofluorocarbons have already been phased out under the Montreal Protocol due to concerns about ozone depletion and provide an illustration of how emission reductions avoid multiple centuries of future TSLR. We examine the "world avoided" by the Montreal Protocol by showing that if these gases had instead been eliminated in 2050, additional TSLR of up to about 14 cm would be expected in the 21st century, with continuing contributions lasting more than 500 y. Emissions of the hydrofluorocarbon substitutes in the next half-century would also contribute to centuries of future TSLR. Consideration of the time scales of reversibility of TSLR due to short-lived substances provides insights into physical processes: sea-level rise is often assumed to follow air temperature, but this assumption holds only for TSLR when temperatures are increasing. We present a more complete formulation that is accurate even when atmospheric temperatures are stable or decreasing due to reductions in short-lived gases or net radiative forcing.

The early atmosphere: a new picture.

PubMed

Levine, J S

1986-01-01

Over the last several years, many of the fundamental ideas concerning the composition and chemical evolution of the Earth's early atmosphere have changed. While many aspects of this subject are clouded--either uncertain or unknown, a new picture is emerging. We are just beginning to understand how astronomical, geochemical, and atmospheric processes each contributed to the development of the gaseous envelope around the third planet from the sun some 4.6 billion years ago and how that envelope chemically evolved over the history of our planet. Simple compounds in that gaseous envelope, energized by atmospheric lightning and/or solar ultraviolet radiation, formed molecules of increasing complexity that eventually evolved into the first living systems on our planet. This process is called "chemical evolution" and immediately preceded biological evolution; once life developed and evolved, it began to alter the chemical composition of the atmosphere that provided the very essence of its creation. Photosynthetic organisms which have the ability to biochemically transform carbon dioxide and water to carbohydrates, which they use for food, produce large amounts of molecular oxygen (O2) as a by-product of the reaction. Atmospheric oxygen photochemically formed ozone, which absorbs ultraviolet radiation from the sun and shields the Earth's surface from this biologically lethal radiation. Once atmospheric ozone levels increased sufficiently, life could leave the safety of the oceans and go ashore for the first time. Throughout the history of our planet, there has been strong interaction between life and the atmosphere. Understanding our cosmic roots is particularly relevant as we embark on a search for life outside the Earth. At this very moment, several radio telescopes around the world are searching for extraterrestrial intelligence (SETI).

Detecting anthropogenic footprints in regional and global sea level rise since 1900

NASA Astrophysics Data System (ADS)

Dangendorf, S.; Marcos, M.; Piecuch, C. G.; Jensen, J.

2015-12-01

While there is scientific consensus that global and local mean sea level (GMSL and LMSL) is rising since the late 19th century, it remains unclear how much of this rise is due to natural variability or anthropogenic forcing. Distinguishing both contributions requires an extensive knowledge about the persistence of natural high and low stands in GMSL and LMSL. This is challenging, since observational time series represent the superposition of various processes with different spectral properties. Here we provide a probabilistic upper range of long-term persistent natural GMSL/LMSL variability (P=0.99), which in turn determines the minimum/maximum anthropogenic contribution since 1900. To account for different spectral characteristics of various contributing processes, we separate LMSL (corrected for vertical land motion) into a slowly varying volumetric (mass and density changes) and a more rapidly changing atmospheric component. Based on a combination of spectral analyses of tide gauge records, barotropic and baroclinic ocean models and numerical Monte-Carlo experiments, we find that in records where transient atmospheric processes dominate the spectra, the persistence of natural volumetric changes tends to be underestimated. If each component is assessed separately, natural centennial trends are locally up to ~1.0 mm/yr larger than in case of an integrated assessment, therefore erroneously enhancing the significance of anthropogenic footprints. The GMSL, however, remains unaffected by such biases. On the basis of a model assessment of the separate components, we conclude that it is virtually certain (P=0.99) that at least 45% of the observed increase in GMSL is of anthropogenic origin.

Thin Ice Clouds in Far IR Experiment: TICFIRE

NASA Astrophysics Data System (ADS)

Blanchet, Jean-Pierre

The TICFIRE mission concept developed with the support of the Canadian Space Agency aims: 1) to improve measurements of water-vapor concentration in the low limit, where cold regions are most sensitive and 2) to determine the contribution of Thin Ice Clouds (TIC) to the energy balance and the role of their microphysical properties on atmospheric cooling. TICFIRE is a process-oriented mission on a micro-satellite platform dedicated to observe key parameters of TIC forming in the cold regions of the Poles and globally, in the upper troposphere. It locates cloud top profiles at the limb and measures at nadir the corresponding upwelling radiance of the atmosphere directly in the thermal window and in the Far Infrared (FIR) spectrum over cold geographical regions, precisely where most of the atmospheric thermal cooling takes place. Due to technological limitations, the FIR spectrum (17 to 50 m) is not regularly monitored by conventional sensors despite its major importance. This deficiency in key data also impacts operational weather forecasting. TICFIRE will provide on a global scale a needed contribution in calibrated radiance assimilation near the IR maximum emission to improve weather forecast. Therefore, TICFIRE is a science-driven mission with a strong operational component.

Evolution of the chemical fingerprint of biomass burning organic aerosol during aging

NASA Astrophysics Data System (ADS)

Bertrand, Amelie; Stefenelli, Giulia; Jen, Coty N.; Pieber, Simone M.; Bruns, Emily A.; Ni, Haiyan; Temime-Roussel, Brice; Slowik, Jay G.; Goldstein, Allen H.; El Haddad, Imad; Baltensperger, Urs; Prévôt, André S. H.; Wortham, Henri; Marchand, Nicolas

2018-06-01

A thermal desorption aerosol gas chromatograph coupled to a high resolution - time of flight - aerosol mass spectrometer (TAG-AMS) was connected to an atmospheric chamber for the molecular characterization of the evolution of organic aerosol (OA) emitted by woodstove appliances for residential heating. Two log woodstoves (old and modern) and one pellet stove were operated under typical conditions. Emissions were aged during a time equivalent to 5 h of atmospheric aging. The five to seven samples were collected and analyzed with the TAG-AMS during each experiment. We detected and quantified over 70 compounds, including levoglucosan and nitrocatechols. We calculate the emission factor (EF) of these tracers in the primary emissions and highlight the influence of the combustion efficiency on these emissions. Smoldering combustion contributes to a higher EF and a more complex composition. We also demonstrate the effect of atmospheric aging on the chemical fingerprint. The tracers are sorted into three categories according to the evolution of their concentration: primary compounds, non-conventional primary compounds, and secondary compounds. For each, we provide a quantitative overview of their contribution to the OA mass at different times of the photo-oxidative process.

Updated operational protocols for the U.S. Geological Survey Precipitation Chemistry Quality Assurance Project in support of the National Atmospheric Deposition Program

USGS Publications Warehouse

Wetherbee, Gregory A.; Martin, RoseAnn

2017-02-06

The U.S. Geological Survey Branch of Quality Systems operates the Precipitation Chemistry Quality Assurance Project (PCQA) for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and National Atmospheric Deposition Program/Mercury Deposition Network (NADP/MDN). Since 1978, various programs have been implemented by the PCQA to estimate data variability and bias contributed by changing protocols, equipment, and sample submission schemes within NADP networks. These programs independently measure the field and laboratory components which contribute to the overall variability of NADP wet-deposition chemistry and precipitation depth measurements. The PCQA evaluates the quality of analyte-specific chemical analyses from the two, currently (2016) contracted NADP laboratories, Central Analytical Laboratory and Mercury Analytical Laboratory, by comparing laboratory performance among participating national and international laboratories. Sample contamination and stability are evaluated for NTN and MDN by using externally field-processed blank samples provided by the Branch of Quality Systems. A colocated sampler program evaluates the overall variability of NTN measurements and bias between dissimilar precipitation gages and sample collectors.This report documents historical PCQA operations and general procedures for each of the external quality-assurance programs from 2007 to 2016.

Solving for the Surface: An Automated Approach to THEMIS Atmospheric Correction

NASA Astrophysics Data System (ADS)

Ryan, A. J.; Salvatore, M. R.; Smith, R.; Edwards, C. S.; Christensen, P. R.

2013-12-01

Here we present the initial results of an automated atmospheric correction algorithm for the Thermal Emission Imaging System (THEMIS) instrument, whereby high spectral resolution Thermal Emission Spectrometer (TES) data are queried to generate numerous atmospheric opacity values for each THEMIS infrared image. While the pioneering methods of Bandfield et al. [2004] also used TES spectra to atmospherically correct THEMIS data, the algorithm presented here is a significant improvement because of the reduced dependency on user-defined inputs for individual images. Additionally, this technique is particularly useful for correcting THEMIS images that have captured a range of atmospheric conditions and/or surface elevations, issues that have been difficult to correct for using previous techniques. Thermal infrared observations of the Martian surface can be used to determine the spatial distribution and relative abundance of many common rock-forming minerals. This information is essential to understanding the planet's geologic and climatic history. However, the Martian atmosphere also has absorptions in the thermal infrared which complicate the interpretation of infrared measurements obtained from orbit. TES has sufficient spectral resolution (143 bands at 10 cm-1 sampling) to linearly unmix and remove atmospheric spectral end-members from the acquired spectra. THEMIS has the benefit of higher spatial resolution (~100 m/pixel vs. 3x5 km/TES-pixel) but has lower spectral resolution (8 surface sensitive spectral bands). As such, it is not possible to isolate the surface component by unmixing the atmospheric contribution from the THEMIS spectra, as is done with TES. Bandfield et al. [2004] developed a technique using atmospherically corrected TES spectra as tie-points for constant radiance offset correction and surface emissivity retrieval. This technique is the primary method used to correct THEMIS but is highly susceptible to inconsistent results if great care in the selection of TES spectra is not exercised. Our algorithm implements a newly populated TES database that was created using PostgreSQL/PostGIS geospatial database. TES pixels that meet user-defined quality criteria and that intersect a THEMIS observation of interest may be quickly retrieved using this new database. The THEMIS correction process [Bandfield et al. 2004] is then run using all TES pixels that pass an additional set of TES-THEMIS relational quality checks. The result is a spatially correlated set of atmospheric opacity values, determined from the difference between each atmospherically corrected TES pixel and the overlapping portion of the THEMIS image. The dust and ice contributions to the atmospheric opacity are estimated using known dust and ice spectral dependencies [Smith et al. 2003]. These opacity values may be used to determine atmospheric variation across the scene, from which topography- and temperature-scaled atmospheric contribution may be calculated and removed. References: Bandfield, JL et al. [2004], JGR 109, E10008. Smith, MD et al. [2003], JGR 108, E11, 5115.

Biodiversity and ecosystem processes: lessons from nature to improve management of planted forests for REDD-plus

Treesearch

Ian D. Thompson; Kimiko Okabe; John A. Parrotta; David I. Forrester; Eckehard Brockerhoff; Hervé Jactel; Hisatomo Taki

2014-01-01

Planted forests are increasingly contributing wood products and other ecosystem services at a global scale. These forests will be even more important as carbon markets develop and REDD-plus forest programs (forests used specifically to reduce atmospheric emissions of CO2 through deforestation and forest degradation) become common. Restoring degraded and deforested...

A STUDY OF PROCESS CONTRIBUTIONS TO OZONE FORMATION DURING THE 2004 ICARTT PERIOD USING THE ETA-CMAQ FORECAST MODEL OVER THE NORTHEASTERN U.S.

EPA Science Inventory

First, this study evaluates the Eta-CMAQ forecast model performances for O₃, and related chemical species with the observational data from the aircraft (NOAA P-3 and NASA DC-8) flights, Lidar and ozonesonde during the 2004 International Consortium for Atmospheric Resea...

A STUDY OF PROCESS CONTRIBUTIONS TO OZONE FORMATION DURING THE 2004 ICARTT PERIOD USING THE ETA- CMAQ FORECAST MODEL OVER THE NORTHEASTERN U.S.

EPA Science Inventory

First, this study evaluates the Eta-CMAQ forecast model performances for O₃, and related chemical species with the observational data from the aircraft (NOAA P-3 and NASA DC-8) flights, Lidar and ozonesonde during the 2004 International Consortium for Atmospheric Resea...

Land-use change effects on fluxes and isotopic composition of CO2 and CH4 in Panama, and possible insights into the atmospheric H2 cycle

NASA Astrophysics Data System (ADS)

Pendall, E.; Schwendenmann, L.; Potvin, C.

2003-12-01

Land-use changes in tropical regions are believed to release a quantity of C to the atmosphere which is similar in magnitude to the entire "missing" sink for anthropogenic CO2. Our research attempts to evaluate carbon cycling in three land-cover systems in central Panama: cow pasture, native tree plantation, and undisturbed moist forest. In this ongoing project, we are collecting samples of air from profiles in the stable, nocturnal boundary layer, which is dominated by ecosystem respiration. Samples are analyzed for CO2 and its isotopes, CH4 and its C isotopic composition, N2O, H2, CO, and SF6. We use a flux-gradient method to estimate ecosystem-scale fluxes of trace gases from soil to the atmosphere. Keeling plot intercepts reflect the respiratory contribution of C3 and C4 biomass under contrasting land cover systems, and how this varies with pronounced wet-dry seasonal cycles. C isotopes of methane and gradients of molecular hydrogen provide insight into the source of methane production from pasture and plantation soils. Rainforest soils, in contrast, are sinks for both atmospheric methane and hydrogen. The process oriented nature of this field experiment will contribute to parameterization of carbon cycle models at a variety of spatial scales.

Using Ground Measurements to Examine the Surface Layer Parameterization Scheme in NCEP GFS

NASA Astrophysics Data System (ADS)

Zheng, W.; Ek, M. B.; Mitchell, K.

2017-12-01

Understanding the behavior and the limitation of the surface layer parameneterization scheme is important for parameterization of surface-atmosphere exchange processes in atmospheric models, accurate prediction of near-surface temperature and identifying the role of different physical processes in contributing to errors. In this study, we examine the surface layer paramerization scheme in the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) using the ground flux measurements including the FLUXNET data. The model simulated surface fluxes, surface temperature and vertical profiles of temperature and wind speed are compared against the observations. The limits of applicability of the Monin-Obukhov similarity theory (MOST), which describes the vertical behavior of nondimensionalized mean flow and turbulence properties within the surface layer, are quantified in daytime and nighttime using the data. Results from unstable regimes and stable regimes are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levine, Paul A.; Randerson, James T.; Swenson, Sean C.

The relationship between terrestrial water storage (TWS) and atmospheric processes has important implications for predictability of climatic extremes and projection of future climate change. In places where moisture availability limits evapotranspiration (ET), variability in TWS has the potential to influence surface energy fluxes and atmospheric conditions. Where atmospheric conditions, in turn, influence moisture availability, a full feedback loop exists. Here we developed a novel approach for measuring the strength of both components of this feedback loop, i.e., the forcing of the atmosphere by variability in TWS and the response of TWS to atmospheric variability, using satellite observations of TWS, precipitation,more » solar radiation, and vapor pressure deficit during 2002–2014. Our approach defines metrics to quantify the relationship between TWS anomalies and climate globally on a seasonal to interannual timescale. Metrics derived from the satellite data were used to evaluate the strength of the feedback loop in 38 members of the Community Earth System Model (CESM) Large Ensemble (LENS) and in six models that contributed simulations to phase 5 of the Coupled Model Intercomparison Project (CMIP5). We found that both forcing and response limbs of the feedback loop in LENS were stronger than in the satellite observations in tropical and temperate regions. Feedbacks in the selected CMIP5 models were not as strong as those found in LENS, but were still generally stronger than those estimated from the satellite measurements. Consistent with previous studies conducted across different spatial and temporal scales, our analysis suggests that models may overestimate the strength of the feedbacks between the land surface and the atmosphere. Lastly, we describe several possible mechanisms that may contribute to this bias, and discuss pathways through which models may overestimate ET or overestimate the sensitivity of ET to TWS.« less

Modeling study of natural emissions, source apportionment, and emission control of atmospheric mercury

NASA Astrophysics Data System (ADS)

Shetty, Suraj K.

Mercury (Hg) is a toxic pollutant and is important to understand its cycling in the environment. In this dissertation, a number of modeling investigations were conducted to better understand the emission from natural surfaces, the source-receptor relationship of the emissions, and emission reduction of atmospheric mercury. The first part of this work estimates mercury emissions from vegetation, soil and water surfaces using a number of natural emission processors and detailed (LAI) Leaf Area Index data from GIS (Geographic Information System) satellite products. East Asian domain was chosen as it contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. The estimated annual natural mercury emissions (gaseous elemental mercury) in the domain are 834 Mg yr-1 with 462 Mg yr-1 contributing from China. Compared to anthropogenic sources, natural sources show greater seasonal variability (highest in simmer). The emissions are significant, sometimes dominant, contributors to total mercury emission in the regions. The estimates provide possible explanation for the gaps between the anthropogenic emission estimates based on activity data and the emission inferred from field observations in the regions. To understand the contribution of domestic emissions to mercury deposition in the United States, the second part of the work applies the mercury model of Community Multi-scale Air Quality Modeling system (CMAQ-Hg v4.6) to apportion the various emission sources attributing to the mercury wet and dry deposition in the 6 United States receptor regions. Contributions to mercury deposition from electric generating units (EGU), iron and steel industry (IRST), industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC) in domain was estimated. The model results for 2005 compared reasonably well to field observations made by MDN (Mercury Deposition Network) and CAMNet (Canadian Atmospheric Mercury Measurement Network). The model estimated a total deposition of 474 Mg yr-1 to the CONUS (Contiguous United States) domain, with two-thirds being dry deposited. Reactive gaseous mercury contributed the most to 60% of deposition. Emission speciation distribution is a key factor for local deposition as contribution from large point sources can be as high as 75% near (< 100 km) the emission sources, indicating that emission reduction may result in direct deposition decrease near the source locations. Among the sources, BC contributes to about 68% to 91% of total deposition. Excluding the BC's contribution, EGU contributes to nearly 50% of deposition caused by CONUS emissions in the Northeast, Southeast and East Central regions, while emissions from natural processes are more important in the Pacific and West Central regions (contributing up to 40% of deposition). The modeling results implies that implementation of the new emission standards proposed by USEPA (United States Environmental Protection Agency) would significantly benefit regions that have larger contributions from EGU sources. Control of mercury emissions from coal combustion processes has attracted great attention due to its toxicity and the emission-control regulations and has lead to advancement in state-of-the-art control technologies that alleviate the impact of mercury on ecosystem and human health. This part of the work applies a sorption model to simulate adsorption of mercury in flue gases, onto a confined-bed of activated carbon. The model's performances were studied at various flue gas flow rates, inlet mercury concentrations and adsorption bed temperatures. The process simulated a flue gas, with inlet mercury concentration of 300 ppb, entering at a velocity of 0.3 m s-1 from the bottom into a fixed bed (inside bed diameter of 1 m and 3 m bed height; bed temperature of 25 °C) of activated carbon (particle size of 0.004 m with density of 0.5 g cm-3 and surface area of 90.25 cm2 g -1). The model result demonstrated that a batch of activated carbon bed was capable of controlling mercury emission for approximately 275 days after which further mercury uptake starts to decrease till it reaches about 500 days when additional control ceases. An increase in bed temperature significantly reduces mercury sorption capacity of the activated carbon. Increase in flue gas flow rate may result in faster consumption of sorption capacity initially but at a later stage, the sorption rate decreases due to reduced sorption capacity. Thus, overall sorption rate remains unaffected. The activated carbon's effective life (time to reach saturation) is not affected by inlet mercury concentration, implying that the designing and operation of a mercury sorption process can be done independently. The results provide quantitative indication for designing efficient confined-bed process to remove mercury from flue gases.

Dications and thermal ions in planetary atmospheric escape

NASA Astrophysics Data System (ADS)

Lilensten, J.; Simon Wedlund, C.; Barthélémy, M.; Thissen, R.; Ehrenreich, D.; Gronoff, G.; Witasse, O.

2013-01-01

In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly energetic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. The goal of this study is to assess the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions. We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO2++ for a simplified single constituent atmosphere of a case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering, etc.), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished and even contribute only marginally to this loss. We show that with these two mechanisms, the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible. When simulating the hot Jupiter HD 209458 b, the two processes cannot explain the measured escape flux of C+. This study shows that the dications may constitute a source of the escape of planetary atmospheres which had not been taken into account until now. This source, although marginal, is not negligible. The influence of the photoionization is of course large, but cannot explain alone the loss of Mars' atmosphere nor the atmospheric escape of HD 209458 b.

Tracing Nitrate Deposition Using Δ 17O

NASA Astrophysics Data System (ADS)

Michalski, G m; Hernandez, L.; Meixner, T.; Fenn, M.; Thiemens, M.

2001-12-01

Assessing the impact of atmospheric deposition of fixed nitrogen on local, regional, and global biogeochemical cycles has received much attention in recent years. Local and regional ecosystems can suffer from eutrophication and shrinking biodiversity from the increased nitrogen flux, in addition to degradation associated with acid rain ( an increasing proportion of which is as HNO3 ). On a global scale, the effect of nitrogen fertilization on CO2 uptake rates is one of the biggest unknowns in global warming research. This renewed interest has led to new attempts to utilize current, and in the development of new, analytical techniques in order to better understand the source, sink and transport mechanisms of atmospheric nitrogen deposition. Its role as the primary sink of the NOx cycle makes atmospheric nitrate (as particulate nitrate or nitric acid ) the primary source of nitrogen deposition. Stable isotopes of nitrogen and oxygen have been used by several researchers to trace atmospheric nitrate through the biogeochemical system. 15N ratios have been problematic due to the lack of large fractionations and an overlap of 15N ratios between sources. Initial studies of 18O ratios showed promise due to the large enrichment (60 ‰ ) in atmospheric nitrate. However, subsequent studies showed an δ 18O spread of 25 - 80 ‰ and have made quantitative analysis of mixing reservoirs difficult. No studies of δ 17O nitrates have been published. For δ 17O, thermodynamic, kinetic, and equilibrium isotope effects dictate that δ 17O = .52 x δ 18O . Certain photochemical processes violate this rule due to quantum effects and are quantified by Δ 17O = δ 17O -.52 x δ 18O which are called mass independent fractionations (MIF). Atmospheric nitrates have now been measured and have been found to have a large MIF; Δ 17O ~ 25 ‰ and a small range +/- 4‰ . The large variations in δ 18O of atmospheric nitrate are due to mass dependent fractions from transport and source ratios, and do not effect the Δ 17O. In addition, post depositional fractionations associated with soil migration and microbial utilization are mass dependent processes. The Δ 17O can then be used as a conservative trace of atmospheric nitrate deposition. A variety of soil measurements demonstrate the practicality of using MIF of atmospheric nitrate as a conservative tracer. Antarctic soils have a Δ 17O ~ 30 ‰ acknowledging they are purely atmospheric in origin. Chilean desert soils with Δ 17O ~ 20 ‰ be 2/3 atmospheric and 1/3 biologically derived. Mojave desert soils Δ 17O range from ~ 0 -16 ‰ indicating that some soils are dominated by biologic nitrification and others have in excess of 50 % atmospheric contribution. Stream waters collected in southern California show a Δ 17O of 0-5 ‰ indicating atmospheric contributions of 0 to 20 %.

On the causes of mid-Pliocene warmth and polar amplification

USGS Publications Warehouse

Lunt, Daniel J.; Haywood, Alan M.; Schmidt, Gavin A.; Salzmann, Ulrich; Valdes, Paul J.; Dowsett, Harry J.; Loptson, Claire A.

2012-01-01

The mid-Pliocene (~ 3 to 3.3 Ma ago), is a period of sustained global warmth in comparison to the late Quaternary (0 to ~ 1 Ma ago), and has potential to inform predictions of long-term future climate change. However, given that several processes potentially contributed, relatively little is understood about the reasons for the observed warmth, or the associated polar amplification. Here, using a modelling approach and a novel factorisation method, we assess the relative contributions to mid-Pliocene warmth from: elevated CO2, lowered orography, and vegetation and ice sheet changes. The results show that on a global scale, the largest contributor to mid-Pliocene warmth is elevated CO2. However, in terms of polar amplification, changes to ice sheets contribute significantly in the Southern Hemisphere, and orographic changes contribute significantly in the Northern Hemisphere. We also carry out an energy balance analysis which indicates that that on a global scale, surface albedo and atmospheric emmissivity changes dominate over cloud changes. We investigate the sensitivity of our results to uncertainties in the prescribed CO2 and orographic changes, to derive uncertainty ranges for the various contributing processes.

Satellite Remote Sensing of the Reactive Lower Atmosphere Using Medium Resolution Infrared Measurements: Highlights from Iasi Mission

NASA Astrophysics Data System (ADS)

Coheur, P. F.

2013-06-01

Human activities have significantly altered the equilibrium of the Earth atmosphere. If the steady increase in the concentration of greenhouse gases has attracted most of the attention, it is important as well to monitor the evolution of our "reactive atmosphere", as shorter-lived atmospheric species impact human health and ecosystems directly (e.g. local air quality) or indirectly (e.g. chemistry-climate interactions), through poorly known and quantified processes. Optical instruments on board satellites, and especially those operating in the infrared with sufficient spectral resolution, provide unique opportunity for measuring reactive trace gases in the troposphere and the stratosphere on various scales. The presentation focuses on the measurements of the Infrared Atmospheric Sounding Interferometer IASI onboard Metop satellites. IASI makes global measurements of the Earth atmosphere in a nadir view, i.e. looking downward at the terrestrial radiation, with a horizontal resolution of a few hundreds km^2. It provides more than 10^6 radiance spectra daily, which cover the infrared range between 645 and 2760 cm^{-1} at medium spectral resolution (0.5 cm^{-1} apodized) and low noise. This, coupled to the exceptional sampling performances of IASI, made breakthroughs in the fields of atmospheric spectroscopy and chemistry. In this talk, we will shortly describe IASI instrument and its spectral measurements, as well as the radiative transfer model and retrieval scheme set up for near-real-time processing. We will review the principal accomplishments of IASI in probing the reactive atmosphere by measuring simultaneously the concentrations of about 25 trace species with short (e.g. NH_3, SO_2) to medium (e.g. O_3, CO) residence time, and from the local emission hotspot to the planetary scale. We will put emphasis on the challenging measurements of the polluted planetary boundary layer and will also show a series of focused results on pollution outflow, transport and in-plume chemistry; possibly global budgets. We will briefly expose how five-years of global measurements can contribute to improve the modeling of processes in the low atmosphere.

The generic MESSy submodel TENDENCY (v1.0) for process-based analyses in Earth system models

NASA Astrophysics Data System (ADS)

Eichinger, R.; Jöckel, P.

2014-07-01

The tendencies of prognostic variables in Earth system models are usually only accessible, e.g. for output, as a sum over all physical, dynamical and chemical processes at the end of one time integration step. Information about the contribution of individual processes to the total tendency is lost, if no special precautions are implemented. The knowledge on individual contributions, however, can be of importance to track down specific mechanisms in the model system. We present the new MESSy (Modular Earth Submodel System) infrastructure submodel TENDENCY and use it exemplarily within the EMAC (ECHAM/MESSy Atmospheric Chemistry) model to trace process-based tendencies of prognostic variables. The main idea is the outsourcing of the tendency accounting for the state variables from the process operators (submodels) to the TENDENCY submodel itself. In this way, a record of the tendencies of all process-prognostic variable pairs can be stored. The selection of these pairs can be specified by the user, tailor-made for the desired application, in order to minimise memory requirements. Moreover, a standard interface allows the access to the individual process tendencies by other submodels, e.g. for on-line diagnostics or for additional parameterisations, which depend on individual process tendencies. An optional closure test assures the correct treatment of tendency accounting in all submodels and thus serves to reduce the model's susceptibility. TENDENCY is independent of the time integration scheme and therefore the concept is applicable to other model systems as well. Test simulations with TENDENCY show an increase of computing time for the EMAC model (in a setup without atmospheric chemistry) of 1.8 ± 1% due to the additional subroutine calls when using TENDENCY. Exemplary results reveal the dissolving mechanisms of the stratospheric tape recorder signal in height over time. The separation of the tendency of the specific humidity into the respective processes (large-scale clouds, convective clouds, large-scale advection, vertical diffusion and methane oxidation) show that the upward propagating water vapour signal dissolves mainly because of the chemical and the advective contribution. The TENDENCY submodel is part of version 2.42 or later of MESSy.

The generic MESSy submodel TENDENCY (v1.0) for process-based analyses in Earth System Models

NASA Astrophysics Data System (ADS)

Eichinger, R.; Jöckel, P.

2014-04-01

The tendencies of prognostic variables in Earth System Models are usually only accessible, e.g., for output, as sum over all physical, dynamical and chemical processes at the end of one time integration step. Information about the contribution of individual processes to the total tendency is lost, if no special precautions are implemented. The knowledge on individual contributions, however, can be of importance to track down specific mechanisms in the model system. We present the new MESSy (Modular Earth Submodel System) infrastructure submodel TENDENCY and use it exemplarily within the EMAC (ECHAM/MESSy Atmospheric Chemistry) model to trace process-based tendencies of prognostic variables. The main idea is the outsourcing of the tendency accounting for the state variables from the process operators (submodels) to the TENDENCY submodel itself. In this way, a record of the tendencies of all process-prognostic variable pairs can be stored. The selection of these pairs can be specified by the user, tailor-made for the desired application, in order to minimise memory requirements. Moreover a standard interface allows the access to the individual process tendencies by other submodels, e.g., for on-line diagnostics or for additional parameterisations, which depend on individual process tendencies. An optional closure test assures the correct treatment of tendency accounting in all submodels and thus serves to reduce the models susceptibility. TENDENCY is independent of the time integration scheme and therefore applicable to other model systems as well. Test simulations with TENDENCY show an increase of computing time for the EMAC model (in a setup without atmospheric chemistry) of 1.8 ± 1% due to the additional subroutine calls when using TENDENCY. Exemplary results reveal the dissolving mechanisms of the stratospheric tape recorder signal in height over time. The separation of the tendency of the specific humidity into the respective processes (large-scale clouds, convective clouds, large-scale advection, vertical diffusion and methane-oxidation) show that the upward propagating water vapour signal dissolves mainly because of the chemical and the advective contribution. The TENDENCY submodel is part of version 2.42 or later of MESSy.

iSPEX: everybody can measure atmospheric aerosols with a smartphone spectropolarimeter

NASA Astrophysics Data System (ADS)

Snik, F.; Heikamp, S.; de Boer, J.; Keller, C. U.; van Harten, G.; Smit, J. M.; Rietjens, J. H. H.; Hasekamp, O.; Stam, D. M.; Volten, H.; iSPEX Team

2012-04-01

An increasing amount people carry a mobile phone with internet connection, camera and large computing power. iSPEX, a spectropolarimetric add-on with complementary app, instantly turns a smartphone into a scientific instrument to measure dust and other aerosols in our atmosphere. A measurement involves scanning the blue sky, which yields the angular behavior of the degree of linear polarization as a function of wavelength, which can unambiguously be interpreted in terms of size, shape and chemical composition of the aerosols in the sky directly above. The measurements are tagged with location and pointing information, and submitted to a central database where they will be interpreted and compiled into an aerosol map. Through crowdsourcing, many people will thus be able to contribute to a better assessment of health risks of particulate matter and of whether or not volcanic ash clouds are dangerous for air traffic. It can also contribute to the understanding of the relationship between atmospheric aerosols and climate change. We will give a live presentation of the first iSPEX prototype. Furthermore, we will present the design and the plans for producing the iSPEX add-on, app and website. We aim to distribute thousands of iSPEX units, such that a unique network of aerosol measurement equipment is created. Many people will thus contribute to the solution of several urgent social and scientific problems, and learn about the nature of light, remote sensing and the issues regarding atmospheric aerosols in the process. In particular we focus on school classes where smartphones are usually considered a nuisance, whereas now they can be a crucial part of various educational programs in science class.

Scale Dependence of Land Atmosphere Interactions in Wet and Dry Regions as Simulated with NU-WRF over the Southwestern and Southeast US

NASA Technical Reports Server (NTRS)

Zhou, Yaping; Wu, Di; Lau, K.- M.; Tao, Wei-Kuo

2016-01-01

Large-scale forcing and land-atmosphere interactions on precipitation are investigated with NASA-Unified WRF (NU-WRF) simulations during fast transitions of ENSO phases from spring to early summer of 2010 and 2011. The model is found to capture major precipitation episodes in the 3-month simulations without resorting to nudging. However, the mean intensity of the simulated precipitation is underestimated by 46% and 57% compared with the observations in dry and wet regions in the southwestern and south-central United States, respectively. Sensitivity studies show that large-scale atmospheric forcing plays a major role in producing regional precipitation. A methodology to account for moisture contributions to individual precipitation events, as well as total precipitation, is presented under the same moisture budget framework. The analysis shows that the relative contributions of local evaporation and large-scale moisture convergence depend on the dry/wet regions and are a function of temporal and spatial scales. While the ratio of local and large-scale moisture contributions vary with domain size and weather system, evaporation provides a major moisture source in the dry region and during light rain events, which leads to greater sensitivity to soil moisture in the dry region and during light rain events. The feedback of land surface processes to large-scale forcing is well simulated, as indicated by changes in atmospheric circulation and moisture convergence. Overall, the results reveal an asymmetrical response of precipitation events to soil moisture, with higher sensitivity under dry than wet conditions. Drier soil moisture tends to suppress further existing below-normal precipitation conditions via a positive soil moisture-land surface flux feedback that could worsen drought conditions in the southwestern United States.

Short-lived halocarbons efficient at influencing climate through ozone loss in the upper troposphere-lower stratosphere

NASA Astrophysics Data System (ADS)

Hossaini, Ryan; Chipperfield, Martyn; Montzka, Steven; Rap, Alex; Dhomse, Sandip; Feng, Wuhu

2015-04-01

Halogenated very short-lived substances (VSLS) of both natural and anthropogenic origin are a significant source of atmospheric bromine, chlorine and iodine. Due to relatively short atmospheric lifetimes (typically <6 months), VSLS breakdown in the upper troposphere-lower stratosphere (UTLS), where ozone perturbations drive a disproportionately large climate impact compared to other altitudes. Here we present chemical transport model simulations that quantify VSLS-driven ozone loss in the UTLS and infer the climate relevance of these ozone perturbations using a radiative transfer model. Our results indicate that through their impact on UTLS ozone, VSLS are efficient at influencing climate. We calculate a whole atmosphere global mean radiative effect (RE) of -0.20 (-0.16 to -0.23) Wm-2 from natural and anthropogenic VSLS-driven ozone loss, including a tropospheric contribution of -0.12 Wm-2. In the stratosphere, the RE due to ozone loss from natural bromine-containing VSLS (e.g. CHBr3, CH2Br2) is almost half of that from long-lived anthropogenic compounds (e.g. CFCs) and normalized by equivalent chlorine is ~4 times larger. We show that the anthropogenic chlorine-containing VSLS, not regulated by the Montreal Protocol, also contribute to ozone loss in the UTLS and that the atmospheric concentration of dichloromethane (CH2Cl2), the most abundant of these, is increasing rapidly. Finally, we present evidence that VSLS have made a small yet previously unrecognized contribution to the ozone-driven radiative forcing of climate since pre-industrial times of -0.02 (-0.01 to -0.03) Wm-2. Given the climate leverage that VSLS possess, future increases to their emissions, either through continued industrial or altered natural processes, may be important for future climate forcing.

Net atmospheric mercury deposition to Svalbard: Estimates from lacustrine sediments

NASA Astrophysics Data System (ADS)

Drevnick, Paul E.; Yang, Handong; Lamborg, Carl H.; Rose, Neil L.

2012-11-01

In this study we used lake sediments, which faithfully record Hg inputs, to derive estimates of net atmospheric Hg deposition to Svalbard, Norwegian Arctic. With the exception of one site affected by local pollution, the study lakes show twofold to fivefold increases in sedimentary Hg accumulation since 1850, likely due to long-range atmospheric transport and deposition of anthropogenic Hg. Sedimentary Hg accumulation in these lakes is a linear function of the ratio of catchment area to lake area, and we used this relationship to model net atmospheric Hg flux: preindustrial and modern estimates are 2.5 ± 3.3 μg m-2 y-1 and 7.0 ± 3.0 μg m-2 y-1, respectively. The modern estimate, by comparison with data for Hg wet deposition, indicates that atmospheric mercury depletion events (AMDEs) or other dry deposition processes contribute approximately half (range 0-70%) of the net flux. Hg from AMDEs may be moving in significant quantities into aquatic ecosystems, where it is a concern because of contamination of aquatic food webs.

Effects of global atmospheric perturbations on forest ecosystems: Predictions of seasonal and cumulative effects

NASA Technical Reports Server (NTRS)

Tinus, R. W.; Roddy, D. J.

1988-01-01

The physical effects of certain large events, such as giant impacts, explosive volcanism, or combined nuclear explosions, have the potential of inducing global catastrophes in our terrestrial environment. Such highly energetic events can inject substantial quantities of material into the atmosphere. In turn, this changes the amount of sunlight reaching the Earth's surface and modifies atmospheric temperatures to produce a wide range of global effects. One consequence is the introduction of serious stresses in both plants and animals throughout the Earth's biosphere. For example, recent studies predict that forest lands, crop lands, and range lands would suffer specific physical and biological degradations if major physical and chemical disruptions occurred in our atmosphere. Forests, which cover over 4 times 10 to the 9th power hectares (4 times 10 to the 7th power sq km) of our planet, or about 3 times the area now cultivated for crops, are critical to many processes in the biosphere. Forests contribute heavily to the production of atmospheric oxygen, supply the major volume of biomass, and provide a significant percentage of plant and animal habitats.

Ambipolar Electric Field, Photoelectrons, and Their Role in Atmospheric Escape From Hot Jupiters

NASA Technical Reports Server (NTRS)

Cohen, O.; Glocer, A.

2012-01-01

Atmospheric mass loss from Hot Jupiters can be large due to the close proximity of these planets to their host star and the strong radiation the planetary atmosphere receives. On Earth, a major contribution to the acceleration of atmospheric ions comes from the vertical separation of ions and electrons, and the generation of the ambipolar electric field. This process, known as the "polar wind," is responsible for the transport of ionospheric constituents to Earth's magnetosphere, where they are well observed. The polar wind can also be enhanced by a relatively small fraction of super-thermal electrons (photoelectrons) generated by photoionization.We formulate a simplified calculation of the effect of the ambipolar electric field and the photoelectrons on the ion scale height in a generalized manner. We find that the ion scale height can be increased by a factor of 2-15 due to the polar wind effects. We also estimate a lower limit of an order of magnitude increase of the ion density and the atmospheric mass-loss rate when polar wind effects are included.

Product Quality of ESA's Atmospheric-Chemistry Missions

NASA Astrophysics Data System (ADS)

Dehn, Angelika; Bojkov, Bojan; Fehr, Thorsten

2012-11-01

ESA's Atmospheric Chemistry Mission is providing fundamental information for the understanding of atmospheric chemistry processes. The global datasets are supporting climate research, air quality assessments, stratospheric ozone monitoring and many other science areas and operational services.ENVISAT with GOMOS, MIPAS and SCIAMACHY has contributed to a unique data set over a period of 10 years, before its major anomaly in April 2012, leading to the end of the operational part of the mission. GOME, on board ERS-2 has been acquiring data for 16 years, before it's de-commissioning in July 2011.The quality of the corresponding data sets is continuously being improved, also beyond the termination of the satellite's operational phases. This is realised with the support of numerous teams of science experts, evolving the algorithm and calibration baseline and validation teams assessing the resulting upgraded data sets.

Episodic inputs of atmospheric nitrogen to the Sargasso Sea: Contributions to new production and phytoplankton blooms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michaels, A.F.; Johnson, R.J.; Siegel, D.A.

1993-06-01

This paper compares a recent atmospheric wet deposition record (including all measurable daily rainfall events between October 1988 and June 1991) with concurrent measurements of nitrogen cycling and biomass at the U.S. Joint Global Ocean Flux Study Bermuda Atlantic Time Series Study station. The two data sets, among the most complete synoptic records of atmospheric nitrogen deposition and ocean nitrogen cycling, provide an opportunity to directly assess the importance of nitrogen deposition in the ocean. The results indicate that individual nitrogen wet deposition events are usually small compared to the ambient nitrogen cycle and that only under sustained calm conditionsmore » following large deposition events will nitrogen deposition processes be an important signal for the understanding of ocean biochemistry. 46 refs., 7 figs.« less

Cloud Chemistry in the United States: Problems and Prospects

NASA Astrophysics Data System (ADS)

Carlton, A. G.; Barth, M. C.; Lance, S.; Fahey, K.; McNeill, V. F.; Weber, R. J.

2017-12-01

Clouds cover 60% of the Earth's surface at a given time and are the primary means by which atmospheric trace species are lofted from the polluted boundary layer to the free troposphere. Clouds also play an important role as atmospheric aqueous phase reactors, scavenging soluble gas phase precursors and providing a medium for oxidation reactions that yield lower volatility products that contribute to increased aerosol mass when cloud drops evaporate. On a global average, most sulfate particles are formed during cloud processing, and organic particles known to form through aqueous phase pathways are found above clouds. However, atmospheric chemistry observations are generally biased for clear sky conditions. For example, aircraft field deployments typically avoid clouds. Satellite retrievals impacted by clouds are often screened from the final data products. This hinders knowledge of cloud chemistry and the impacts on tropospheric composition. In this work, we explore temporal and geospatial trends in trace species related to cloud processing in the U.S. with a focus on organic chemistry. We apply 3-dimensional and 0-dimensional models to recent campaigns and mountaintop cloud sampling sites, and compare to measurements.

Atmospheric River Characteristics under Decadal Climate Variability

NASA Astrophysics Data System (ADS)

Done, J.; Ge, M.

2017-12-01

How does decadal climate variability change the nature and predictability of atmospheric river events? Decadal swings in atmospheric river frequency, or shifts in the proportion of precipitation falling as rain, could challenge current water resource and flood risk management practice. Physical multi-scale processes operating between Pacific sea surface temperatures (SSTs) and atmospheric rivers over the Western U.S. are explored using the global Model for Prediction Across Scales (MPAS). A 45km global mesh is refined over the Western U.S. to 12km to capture the major terrain effects on precipitation. The performance of the MPAS is first evaluated for a case study atmospheric river event over California. Atmospheric river characteristics are then compared in a pair of idealized simulations, each driven by Pacific SST patterns characteristic of opposite phases of the Interdecadal Pacific Oscillation (IPO). Given recent evidence that we have entered a positive phase of the IPO, implications for current reservoir management practice over the next decade will be discussed. This work contributes to the NSF-funded project UDECIDE (Understanding Decision-Climate Interactions on Decadal Scales). UDECIDE brings together practitioners, engineers, statisticians, and climate scientists to understand the role of decadal climate information for water management and decisions.

Evaluation of atmospheric correction algorithms for processing SeaWiFS data

NASA Astrophysics Data System (ADS)

Ransibrahmanakul, Varis; Stumpf, Richard; Ramachandran, Sathyadev; Hughes, Kent

2005-08-01

To enable the production of the best chlorophyll products from SeaWiFS data NOAA (Coastwatch and NOS) evaluated the various atmospheric correction algorithms by comparing the satellite derived water reflectance derived for each algorithm with in situ data. Gordon and Wang (1994) introduced a method to correct for Rayleigh and aerosol scattering in the atmosphere so that water reflectance may be derived from the radiance measured at the top of the atmosphere. However, since the correction assumed near infrared scattering to be negligible in coastal waters an invalid assumption, the method over estimates the atmospheric contribution and consequently under estimates water reflectance for the lower wavelength bands on extrapolation. Several improved methods to estimate near infrared correction exist: Siegel et al. (2000); Ruddick et al. (2000); Stumpf et al. (2002) and Stumpf et al. (2003), where an absorbing aerosol correction is also applied along with an additional 1.01% calibration adjustment for the 412 nm band. The evaluation show that the near infrared correction developed by Stumpf et al. (2003) result in an overall minimum error for U.S. waters. As of July 2004, NASA (SEADAS) has selected this as the default method for the atmospheric correction used to produce chlorophyll products.

Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

NASA Astrophysics Data System (ADS)

Travnikov, Oleg; Angot, Hélène; Artaxo, Paulo; Bencardino, Mariantonia; Bieser, Johannes; D'Amore, Francesco; Dastoor, Ashu; De Simone, Francesco; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Magand, Olivier; Martin, Lynwill; Matthias, Volker; Mashyanov, Nikolay; Pirrone, Nicola; Ramachandran, Ramesh; Read, Katie Alana; Ryjkov, Andrei; Selin, Noelle E.; Sena, Fabrizio; Song, Shaojie; Sprovieri, Francesca; Wip, Dennis; Wängberg, Ingvar; Yang, Xin

2017-04-01

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM / GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM / GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation. Hence, the performance of the Hg oxidation mechanisms under study differs in the extent to which they can reproduce the various observed parameters. This variation implies possibility of more complex chemistry and multiple Hg oxidation pathways occurring concurrently in various parts of the atmosphere.

Volatile inventory and early evolution of the planetary atmospheres

NASA Astrophysics Data System (ADS)

Marov, Mikhail Ya.; Ipatov, Sergei I.

Formation of atmospheres of the inner planets involved the concurrent processes of mantle degassing and collisions that culminated during the heavy bombardment. Volatile-rich icy planetesimals impacting on the planets as a late veneer strongly contributed to the volatile inventory. Icy remnants of the outer planet accretion significantly complemented the accumulation of the lithophile and atmophile elements forced out onto the surface of the inner planets from silicate basaltic magma enriched in volatiles. Orbital dynamics of small bodies, including near-Earth asteroids, comets, and bodies from the Edgeworth-Kuiper belt evolving to become inner planet crossers, is addressed to examine different plausible amounts of volatile accretion. The relative importance of comets and chondrites in the delivery of volatiles is constrained by the observed fractionation pattern of noble gas abundances in the atmospheres of inner planets. The following development of the early atmospheres depended on the amount of volatiles expelled from the interiors and deposited by impactors, while the position of the planet relative to the Sun and its mass affected its climatic evolution.

Interannual variability of terrestrial NEP and its attributions to carbon uptake amplitude and period

NASA Astrophysics Data System (ADS)

Niu, S.

2015-12-01

Earth system exhibits strong interannual variability (IAV) in the global carbon cycle as reflected in the year-to-year anomalies of the atmospheric CO2 concentration. Although various analyses suggested that land ecosystems contribute mostly to the IAV of atmospheric CO2 concentration, processes leading to the IAV in the terrestrial carbon (C) cycle are far from clear and hinder our effort in predicting the IAV of global C cycle. Previous studies on IAV of global C cycle have focused on the regulation of climatic variables in tropical or semiarid areas, but generated inconsistent conclusions. Using long-term eddy-flux measurements of net ecosystem production (NEP), atmospheric CO2 inversion NEP, and the MODIS-derived gross primary production (GPP), we demonstrate that seasonal carbon uptake amplitude (CUA) and period (CUP) are two key processes that control the IAV in the terrestrial C cycle. The two processes together explain 78% of the variations in the IAV in eddy covariance NEP, 70% in global atmospheric inversed NEP, and 53% in the IAV of GPP. Moreover, the three lines of evidence consistently show that variability in CUA is much more important than that of CUP in determining the variation of NEP at most eddy-flux sites, and most grids of global NEP and GPP. Our results suggest that the maximum carbon uptake potential in the peak-growing season is a determinant process of global C cycle internnual variability and carbon uptake period may play less important role than previous expectations. This study uncovers the most parsimonious, proximate processes underlying the IAV in global C cycle of the Earth system. Future research is needed to identify how climate factors affect the IAV in terrestrial C cycle through their influence on CUA and CUP.

Informed Source Separation of Atmospheric and Surface Signal Contributions in Shortwave Hyperspectral Imagery using Non-negative Matrix Factorization

NASA Astrophysics Data System (ADS)

Wright, L.; Coddington, O.; Pilewskie, P.

2015-12-01

Current challenges in Earth remote sensing require improved instrument spectral resolution, spectral coverage, and radiometric accuracy. Hyperspectral instruments, deployed on both aircraft and spacecraft, are a growing class of Earth observing sensors designed to meet these challenges. They collect large amounts of spectral data, allowing thorough characterization of both atmospheric and surface properties. The higher accuracy and increased spectral and spatial resolutions of new imagers require new numerical approaches for processing imagery and separating surface and atmospheric signals. One potential approach is source separation, which allows us to determine the underlying physical causes of observed changes. Improved signal separation will allow hyperspectral instruments to better address key science questions relevant to climate change, including land-use changes, trends in clouds and atmospheric water vapor, and aerosol characteristics. In this work, we investigate a Non-negative Matrix Factorization (NMF) method for the separation of atmospheric and land surface signal sources. NMF offers marked benefits over other commonly employed techniques, including non-negativity, which avoids physically impossible results, and adaptability, which allows the method to be tailored to hyperspectral source separation. We adapt our NMF algorithm to distinguish between contributions from different physically distinct sources by introducing constraints on spectral and spatial variability and by using library spectra to inform separation. We evaluate our NMF algorithm with simulated hyperspectral images as well as hyperspectral imagery from several instruments including, the NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), NASA Hyperspectral Imager for the Coastal Ocean (HICO) and National Ecological Observatory Network (NEON) Imaging Spectrometer.

Towards a physical understanding of stratospheric cooling under global warming through a process-based decomposition method

NASA Astrophysics Data System (ADS)

Yang, Yang; Ren, R.-C.; Cai, Ming

2016-12-01

The stratosphere has been cooling under global warming, the causes of which are not yet well understood. This study applied a process-based decomposition method (CFRAM; Coupled Surface-Atmosphere Climate Feedback Response Analysis Method) to the simulation results of a Coupled Model Intercomparison Project, phase 5 (CMIP5) model (CCSM4; Community Climate System Model, version 4), to demonstrate the responsible radiative and non-radiative processes involved in the stratospheric cooling. By focusing on the long-term stratospheric temperature changes between the "historical run" and the 8.5 W m-2 Representative Concentration Pathway (RCP8.5) scenario, this study demonstrates that the changes of radiative radiation due to CO2, ozone and water vapor are the main divers of stratospheric cooling in both winter and summer. They contribute to the cooling changes by reducing the net radiative energy (mainly downward radiation) received by the stratospheric layer. In terms of the global average, their contributions are around -5, -1.5, and -1 K, respectively. However, the observed stratospheric cooling is much weaker than the cooling by radiative processes. It is because changes in atmospheric dynamic processes act to strongly mitigate the radiative cooling by yielding a roughly 4 K warming on the global average base. In particular, the much stronger/weaker dynamic warming in the northern/southern winter extratropics is associated with an increase of the planetary-wave activity in the northern winter, but a slight decrease in the southern winter hemisphere, under global warming. More importantly, although radiative processes dominate the stratospheric cooling, the spatial patterns are largely determined by the non-radiative effects of dynamic processes.

Attribution of regional flood changes based on scaling fingerprints

PubMed Central

Merz, Bruno; Viet Dung, Nguyen; Parajka, Juraj; Nester, Thomas; Blöschl, Günter

2016-01-01

Abstract Changes in the river flood regime may be due to atmospheric processes (e.g., increasing precipitation), catchment processes (e.g., soil compaction associated with land use change), and river system processes (e.g., loss of retention volume in the floodplains). This paper proposes a new framework for attributing flood changes to these drivers based on a regional analysis. We exploit the scaling characteristics (i.e., fingerprints) with catchment area of the effects of the drivers on flood changes. The estimation of their relative contributions is framed in Bayesian terms. Analysis of a synthetic, controlled case suggests that the accuracy of the regional attribution increases with increasing number of sites and record lengths, decreases with increasing regional heterogeneity, increases with increasing difference of the scaling fingerprints, and decreases with an increase of their prior uncertainty. The applicability of the framework is illustrated for a case study set in Austria, where positive flood trends have been observed at many sites in the past decades. The individual scaling fingerprints related to the atmospheric, catchment, and river system processes are estimated from rainfall data and simple hydrological modeling. Although the distributions of the contributions are rather wide, the attribution identifies precipitation change as the main driver of flood change in the study region. Overall, it is suggested that the extension from local attribution to a regional framework, including multiple drivers and explicit estimation of uncertainty, could constitute a similar shift in flood change attribution as the extension from local to regional flood frequency analysis. PMID:27609996

Advancement of Techniques for Modeling the Effects of Atmospheric Gravity-Wave-Induced Inhomogeneities on Infrasound Propagation

DTIC Science & Technology

2010-09-01

ADVANCEMENT OF TECHNIQUES FOR MODELING THE EFFECTS OF ATMOSPHERIC GRAVITY-WAVE-INDUCED INHOMOGENEITIES ON INFRASOUND PROPAGATION Robert G...number of infrasound observations indicate that fine-scale atmospheric inhomogeneities contribute to infrasonic arrivals that are not predicted by...standard modeling techniques. In particular, gravity waves, or buoyancy waves, are believed to contribute to the multipath nature of infrasound

Source Contributions to Wintertime Elemental and Organic Carbon in the Western Arctic Based on Radiocarbon and Tracer Apportionment.

PubMed

Barrett, T E; Robinson, E M; Usenko, S; Sheesley, R J

2015-10-06

To quantify the contributions of fossil and biomass sources to the wintertime Arctic aerosol burden source apportionment is reported for elemental (EC) and organic carbon (OC) fractions of six PM10 samples collected during a wintertime (2012-2013) campaign in Barrow, AK. Radiocarbon apportionment of EC indicates that fossil sources contribute an average of 68 ± 9% (0.01-0.07 μg m(-3)) in midwinter decreasing to 49 ± 6% (0.02 μg m(-3)) in late winter. The mean contribution of fossil sources to OC for the campaign was stable at 38 ± 8% (0.04-0.32 μg m(-3)). Samples were also analyzed for organic tracers, including levoglucosan, for use in a chemical mass balance (CMB) source apportionment model. The CMB model was able to apportion 24-53% and 99% of the OC and EC burdens, respectively, during the campaign, with fossil OC contributions ranging from 25 to 74% (0.02-0.09 μg m(-3)) and fossil EC contributions ranging from 73 to 94% (0.03-0.07 μg m(-3)). Back trajectories identified two major wintertime source regions to Barrow: the Russian and North American Arctic. Atmospheric lifetimes of levoglucosan, ranging from 50 to 320 h, revealed variability in wintertime atmospheric processing of this biomass burning tracer. This study allows for unambiguous apportionment of EC to fossil fuel and biomass combustion sources and intercomparison with CMB modeling.

Land-atmosphere coupling and soil moisture memory contribute to long-term agricultural drought

NASA Astrophysics Data System (ADS)

Kumar, S.; Newman, M.; Lawrence, D. M.; Livneh, B.; Lombardozzi, D. L.

2017-12-01

We assessed the contribution of land-atmosphere coupling and soil moisture memory on long-term agricultural droughts in the US. We performed an ensemble of climate model simulations to study soil moisture dynamics under two atmospheric forcing scenarios: active and muted land-atmosphere coupling. Land-atmosphere coupling contributes to a 12% increase and 36% decrease in the decorrelation time scale of soil moisture anomalies in the US Great Plains and the Southwest, respectively. These differences in soil moisture memory affect the length and severity of modeled drought. Consequently, long-term droughts are 10% longer and 3% more severe in the Great Plains, and 15% shorter and 21% less severe in the Southwest. An analysis of Coupled Model Intercomparsion Project phase 5 data shows four fold uncertainty in soil moisture memory across models that strongly affects simulated long-term droughts and is potentially attributable to the differences in soil water storage capacity across models.

Fabrication of PDMS through-holes using the MIMIC method and the surface treatment by atmospheric-pressure CH4/He RF plasma

NASA Astrophysics Data System (ADS)

Choi, Jongchan; Lee, Kyeong-Hwan; Yang, Sung

2011-09-01

This note presents a simple fabrication process for patterning micro through-holes in a PDMS layer by a combination of the micromolding in capillaries (MIMIC) method and the surface treatment by atmospheric-pressure CH4/He RF plasma. The fabrication process is confirmed by forming micro through-holes with various shapes including circle, C-shape, open microfluidic channel and hemisphere. All micro through-holes of various shapes in a wide range of diameters and heights are well fabricated by the proposed method. Also, a 3D micromixer containing a PDMS micro through-hole layer formed by the proposed method is built and its performance is tested as another practical demonstration of the proposed fabrication method. Therefore, we believe that the proposed fabrication process will build a PDMS micro through-hole layer in a simple and easy way and will contribute to developing highly efficient multi-layered microfluidic systems, which may require PDMS micro through-hole layers.

Contrasting carbon cycle responses of the tropical continents to the 2015-2016 El Niño.

PubMed

Liu, Junjie; Bowman, Kevin W; Schimel, David S; Parazoo, Nicolas C; Jiang, Zhe; Lee, Meemong; Bloom, A Anthony; Wunch, Debra; Frankenberg, Christian; Sun, Ying; O'Dell, Christopher W; Gurney, Kevin R; Menemenlis, Dimitris; Gierach, Michelle; Crisp, David; Eldering, Annmarie

2017-10-13

The 2015-2016 El Niño led to historically high temperatures and low precipitation over the tropics, while the growth rate of atmospheric carbon dioxide (CO 2 ) was the largest on record. Here we quantify the response of tropical net biosphere exchange, gross primary production, biomass burning, and respiration to these climate anomalies by assimilating column CO 2 , solar-induced chlorophyll fluorescence, and carbon monoxide observations from multiple satellites. Relative to the 2011 La Niña, the pantropical biosphere released 2.5 ± 0.34 gigatons more carbon into the atmosphere in 2015, consisting of approximately even contributions from three tropical continents but dominated by diverse carbon exchange processes. The heterogeneity of the carbon-exchange processes indicated here challenges previous studies that suggested that a single dominant process determines carbon cycle interannual variability. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

NASA Astrophysics Data System (ADS)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and interannual variability in these processes. Spatial and temporal patterns of evapotranspiration, groundwater recharge and streamflow generation processes reveal potential hot spots and hot moments for surface and groundwater contamination in this basin.

Mars Science Laboratory Interplanetary Navigation Performance

NASA Technical Reports Server (NTRS)

Martin-Mur, Tomas J.; Kruizinga, Gerhard; Wong, Mau

2013-01-01

The Mars Science Laboratory spacecraft, carrying the Curiosity rover to Mars, hit the top of the Martian atmosphere just 200 meters from where it had been predicted more than six days earlier, and 2.6 million kilometers away. This un-expected level of accuracy was achieved by a combination of factors including: spacecraft performance, tracking data processing, dynamical modeling choices, and navigation filter setup. This paper will describe our best understanding of what were the factors that contributed to this excellent interplanetary trajectory prediction performance. The accurate interplanetary navigation contributed to the very precise landing performance, and to the overall success of the mission.

The atmospheric escape at Mars: complementing the scenario

NASA Astrophysics Data System (ADS)

Lilensten, Jean; Simon, Cyril; Barthélémy, Mathieu; Thissen, Roland; Ehrenreich, David; Gronoff, Guillaume; Witasse, Olivier

2013-04-01

In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly ener- getic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. This study assesses the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions.We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO++ for a simplified single constituent atmosphere of a 2 case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering ...), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished but complement the other processes and allow writing the scenario of the Mars escape. We show that the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible.When simulating the hot Jupiter HD209458b, the two processes cannot explain the measured escape flux of C+.

Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest

DOE PAGES

Zhou, L.; Gierens, R.; Sogachev, A.; ...

2015-08-06

New particle formation (NPF) is an important atmospheric phenomenon. During an NPF event, particles first form by nucleation and then grow further in size. The growth step is crucial because it controls the number of particles that can become cloud condensation nuclei. Among various physical and chemical processes contributing to particle growth, condensation by organic vapors has been suggested as important. In order to better understand the influence of biogenic emissions on particle growth, we carried out modeling studies of NPF events during the BEACHON-ROCS (Bio–hydro–atmosphere interactions of Energy, Aerosol, Carbon, H2O, Organics & Nitrogen – Rocky Mountain Organic Carbonmore » Study) campaign at Manitou Experimental Forest Observatory in Colorado, USA. The site is representative of the semi-arid western USA. With the latest Criegee intermediate reaction rates implemented in the chemistry scheme, the model underestimates sulfuric acid concentration by 50 %, suggesting either missing sources of atmospheric sulfuric acid or an overestimated sink term. The results emphasize the contribution from biogenic volatile organic compound emissions to particle growth by demonstrating the effects of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears to be closely related to the OH oxidation products of MBO.« less

Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, L.; Gierens, R.; Sogachev, A.

2015-01-01

New particle formation (NPF) is an important atmospheric phenomenon. During an NPF event, particles first form by nucleation and then grow further in size. The growth step is crucial because it controls the number of particles that can become cloud condensation nuclei. Among various physical and chemical processes contributing to particle growth, condensation by organic vapors has been suggested as important. In order to better understand the influence of biogenic emissions on particle growth, we carried out modeling studies of NPF events during the BEACHON-ROCS (Bio–hydro–atmosphere interactions of Energy, Aerosol, Carbon, H2O, Organics & Nitrogen – Rocky Mountain Organic Carbonmore » Study) campaign at Manitou Experimental Forest Observatory in Colorado, USA. The site is representative of the semi-arid western USA. With the latest Criegee intermediate reaction rates implemented in the chemistry scheme, the model underestimates sulfuric acid concentration by 50 %, suggesting either missing sources of atmospheric sulfuric acid or an overestimated sink term. The results emphasize the contribution from biogenic volatile organic compound emissions to particle growth by demonstrating the effects of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears to be closely related to the OH oxidation products of MBO.« less

Quantitative and Comprehensive Decomposition of the Ion Atmosphere around Nucleic Acids

PubMed Central

Bai, Yu; Greenfeld, Max; Travers, Kevin; Chu, Vincent B.; Lipfert, Jan; Doniach, Sebastian; Herschlag, Daniel

2011-01-01

The ion atmosphere around nucleic acids critically affects biological and physical processes such as chromosome packing, RNA folding, and molecular recognition. However, the dynamic nature of the ion atmosphere renders it difficult to characterize. The basic thermodynamic description of this atmosphere, a full accounting of the type and number of associated ions, has remained elusive. Here we provide the first complete accounting of the ion atmosphere, using buffer equilibration and atomic emission spectroscopy (BE-AES) to accurately quantitate the cation association and anion depletion. We have examined the influence of ion size and charge on ion occupancy around simple, well-defined DNA molecules. The relative affinity of monovalent and divalent cations correlates inversely with their size. Divalent cations associate preferentially over monovalent cations; e.g., with Na+ in four-fold excess of Mg2+ (20 vs. 5 mM), the ion atmosphere nevertheless has three-fold more Mg2+ than Na+. Further, the dicationic polyamine putrescine2+ does not compete effectively for association relative to divalent metal ions, presumably because of its lower charge density. These and other BE-AES results can be used to evaluate and guide the improvement of electrostatic treatments. As a first step, we compare the BE-AES results to predictions from the widely-used nonlinear Poisson Boltzmann (NLPB) theory and assess the applicability and precision of this theory. In the future, BE-AES in conjunction with improved theoretical models, can be applied to complex binding and folding equilibria of nucleic acids and their complexes, to parse the electrostatic contribution from the overall thermodynamics of important biological processes. PMID:17990882

Decoding mass-independent fractionation of sulfur isotopes in modern atmosphere using cosmogenic 35S: A five-isotope approach and possible implications for Archean sulfur isotope records

NASA Astrophysics Data System (ADS)

Lin, M.; Thiemens, M. H.; Shen, Y.; Zhang, X.; Huang, X.; Chen, K.; Zhang, Z.; Tao, J.

2017-12-01

The signature of sulfur isotopic mass-independent fractionation (S-MIF) observed in Archean sediments have been interpreted as a proxy of the origins and evolution of atmospheric oxygen and early life on Earth [1]. Photochemistry of SOx in the short (< 290 nm) wavelength region accounts for much of the Archean record, but the S-MIF widely observed in modern tropospheric sulfate aerosols remains unexplained, indicating embedded uncertainties in interpreting Archean S-MIF records [2]. Here we present combined measurements of cosmogenic 35S (a stratospheric tracer) [3] and all four stable sulfur isotopes in the same modern atmospheric sulfate samples to define the mechanisms. The five-sulfur-isotope approach reveals that an altitude-dependent process (probably SOx photochemistry) mainly contributes to a positive Δ33S and a combustion-related process mainly leads to a negative Δ36S. After eliminating combustion impacts, the obtained Δ36S/Δ33S slope of -4.0 in the modern atmosphere is close to the Δ36S/Δ33S slope (-3.6) in some records from Paleoarchean [4], an era probably with active volcanism [5]. The significant role of volcanic OCS in the Archean atmosphere has been called for in terms of its ability to provide a continual SO2 high altitude source for photolysis [2]. The strong but previously underappreciated stratospheric signature of S-MIF in tropospheric sulfates suggests that a more careful investigation of wavelength-dependent sulfur isotopic fractionation at different altitudes are required. The combustion-induced negative Δ36S may be linked to recombination reactions of elemental sulfur [6], and relevant experiments are being conducted to test the isotope effect. Although combustion is unlikely in Archean, recombination reactions may occur in other previously unappreciated processes such as volcanism and may contribute in part to the heavily depleted 36S in some Paleoarchean records [5,7]. The roles of both photochemical and non-photochemical reactions in the variability of Archean S-MIF records require further analysis in the future. Refs: [1] Farquhar et al., Science 2000; [2] Shaheen et al., PNAS 2014; [3] Lin et al., PNAS 2016; [4] Wacey et al., Precambrian Res 2015; [5] Muller et al., PNAS 2016; [6] Babikov, PNAS 2017; [7] Shen et al., EPSL, 2009.

Evaluating the strength of the land$-$atmosphere moisture feedback in Earth system models using satellite observations

DOE PAGES

Levine, Paul A.; Randerson, James T.; Swenson, Sean C.; ...

2016-12-09

The relationship between terrestrial water storage (TWS) and atmospheric processes has important implications for predictability of climatic extremes and projection of future climate change. In places where moisture availability limits evapotranspiration (ET), variability in TWS has the potential to influence surface energy fluxes and atmospheric conditions. Where atmospheric conditions, in turn, influence moisture availability, a full feedback loop exists. Here we developed a novel approach for measuring the strength of both components of this feedback loop, i.e., the forcing of the atmosphere by variability in TWS and the response of TWS to atmospheric variability, using satellite observations of TWS, precipitation,more » solar radiation, and vapor pressure deficit during 2002–2014. Our approach defines metrics to quantify the relationship between TWS anomalies and climate globally on a seasonal to interannual timescale. Metrics derived from the satellite data were used to evaluate the strength of the feedback loop in 38 members of the Community Earth System Model (CESM) Large Ensemble (LENS) and in six models that contributed simulations to phase 5 of the Coupled Model Intercomparison Project (CMIP5). We found that both forcing and response limbs of the feedback loop in LENS were stronger than in the satellite observations in tropical and temperate regions. Feedbacks in the selected CMIP5 models were not as strong as those found in LENS, but were still generally stronger than those estimated from the satellite measurements. Consistent with previous studies conducted across different spatial and temporal scales, our analysis suggests that models may overestimate the strength of the feedbacks between the land surface and the atmosphere. Lastly, we describe several possible mechanisms that may contribute to this bias, and discuss pathways through which models may overestimate ET or overestimate the sensitivity of ET to TWS.« less

Estimation of absolute water surface temperature based on atmospherically corrected thermal infrared multispectral scanner digital data

NASA Technical Reports Server (NTRS)

Anderson, James E.

1986-01-01

Airborne remote sensing systems, as well as those on board Earth orbiting satellites, sample electromagnetic energy in discrete wavelength regions and convert the total energy sampled into data suitable for processing by digital computers. In general, however, the total amount of energy reaching a sensor system located at some distance from the target is composed not only of target related energy, but, in addition, contains a contribution originating from the atmosphere itself. Thus, some method must be devised for removing or at least minimizing the effects of the atmosphere. The LOWTRAN-6 Program was designed to estimate atmospheric transmittance and radiance for a given atmospheric path at moderate spectral resolution over an operational wavelength region from 0.25 to 28.5 microns. In order to compute the Thermal Infrared Multispectral Scanner (TIMS) digital values which were recorded in the absence of the atmosphere, the parameters derived from LOWTRAN-6 are used in a correction equation. The TIMS data were collected at 1:00 a.m. local time on November 21, 1983, over a recirculating cooling pond for a power plant in southeastern Mississippi. The TIMS data were analyzed before and after atmospheric corrections were applied using a band ratioing model to compute the absolute surface temperature of various points on the power plant cooling pond. The summarized results clearly demonstrate the desirability of applying atmospheric corrections.

Unstable behaviour of an upper ocean-atmosphere coupled model: role of atmospheric radiative processes and oceanic heat transport

NASA Astrophysics Data System (ADS)

Cohen-Solal, E.; Le Treut, H.

We describe the initial bias of the climate simulated by a coupled ocean-atmosphere model. The atmospheric component is a state-of-the-art atmospheric general circulation model, whereas the ocean component is limited to the upper ocean and includes a mixed layer whose depth is computed by the model. As the full ocean general circulation is not computed by the model, the heat transport within the ocean is prescribed. When modifying the prescribed heat transport we also affect the initial drift of the model. We analyze here one of the experiments where this drift is very strong, in order to study the key processes relating the changes in the ocean transport and the evolution of the model's climate. In this simulation, the ocean surface temperature cools by 1.5°C in 20 y. We can distinguish two different phases. During the first period of 5 y, the sea surface temperatures become cooler, particularly in the intertropical area, but the outgoing longwave radiation at the top-of-the-atmosphere increases very quickly, in particular at the end of the period. An off-line version of the model radiative code enables us to decompose this behaviour into different contributions (cloudiness, specific humidity, air and surface temperatures, surface albedo). This partitioning shows that the longwave radiation evolution is due to a decrease of high level cirrus clouds in the intertropical troposphere. The decrease of the cloud cover also leads to a decrease of the planetary albedo and therefore an increase of the net short wave radiation absorbed by the system. But the dominant factor is the strong destabilization by the longwave cooling, which is able to throw the system out of equilibrium. During the remaining of the simulation (second phase), the cooling induced by the destabilization at the top-of-the-atmosphere is transmitted to the surface by various processes of the climate system. Hence, we show that small variations of ocean heat transport can force the model from a stable to an unstable state via atmospheric processes which arise wen the tropics are cooling. Even if possibly overestimated by our GCM, this mechanism may be pertinent to the maintenance of present climatic conditions in the tropics. The simplifications inherent in our model's design allow us to investigate the mechanism in some detail.

Atmospheric inputs to watersheds of the Luquillo Mountains in eastern Puerto Rico: Chapter D in Water quality and landscape processes of four watersheds in eastern Puerto Rico

USGS Publications Warehouse

Stallard, Robert F.; Murphy, Sheila F.; Stallard, Robert F.

2012-01-01

Twenty years of precipitation-chemistry data from the National Atmospheric Deposition Program site at El Verde, Puerto Rico, demonstrate that three major sources control the composition of solutes in rain in eastern Puerto Rico. In order of importance, these sources are marine salts, temperate contamination from the Northern Hemisphere, and Sahara Desert dust. Marine salts are a source of roughly 82 percent of the ionic charge in precipitation; marine salt inputs are greatest in January. Evaluation of 15 years of U.S. Geological Survey data for four watersheds in eastern Puerto Rico suggests that large storms, including hurricanes, are associated with exceptionally high chloride concentrations in stream waters. Some of these storms were missed in sampling by the National Atmospheric Deposition Program, and therefore its data on the marine contribution likely underestimate chloride. The marine contribution is a weak source of acidity. Temperate contamination contributes about 10 percent of the ionic charge in precipitation; contaminants are primarily nitrate, ammonia, and sulfate derived from various manmade and natural sources. Peak deposition of temperate contaminants is during January, April, and May, months in which strong weather fronts arrive from the north. Temperate contamination, a strong source of acidity, is the only component that is increasing through time. Sahara Desert dust provides 5 percent of the ionic charge in precipitation; it is strongly seasonal, peaking in June and July during times of maximum dust transport from the Sahara and sub-Saharan regions. This dust contributes, on average, enough alkalinity to neutralize the acidity in June and July rains.

Estimation of the contribution of ultrafine particles to lung deposition of particle-bound mutagens in the atmosphere.

PubMed

Kawanaka, Youhei; Matsumoto, Emiko; Sakamoto, Kazuhiko; Yun, Sun-Ja

2011-02-15

The present study was performed to estimate the contributions of fine and ultrafine particles to the lung deposition of particle-bound mutagens in the atmosphere. This is the first estimation of the respiratory deposition of atmospheric particle-bound mutagens. Direct and S9-mediated mutagenicity of size-fractionated particulate matter (PM) collected at roadside and suburban sites was determined by the Ames test using Salmonella typhimurium strain TA98. Regional deposition efficiencies in the human respiratory tract of direct and S9-mediated mutagens in each size fraction were calculated using the LUDEP computer-based model. The model calculations showed that about 95% of the lung deposition of inhaled mutagens is caused by fine particles for both roadside and suburban atmospheres. Importantly, ultrafine particles were shown to contribute to the deposition of mutagens in the alveolar region of the lung by as much as 29% (+S9) and 26% (-S9) for the roadside atmosphere and 11% (+S9) and 13% (-S9) for the suburban atmosphere, although ultrafine particles contribute very little to the PM mass concentration. These results indicated that ultrafine particles play an important role as carriers of mutagens into the lung. Copyright © 2010 Elsevier B.V. All rights reserved.

Isoprene Emissions and Ozone Formation in Urban Conditions: A Case Study in the City of Rio de Janeiro.

PubMed

da Silva, Cleyton Martins; Corrêa, Sergio Machado; Arbilla, Graciela

2018-01-01

The potential role of isoprene oxidative processes, as well as the possible impact of air pollution on isoprene emissions, are more important in tropical cities, surrounded by rainforests. In this study, the contribution of isoprene to ozone formation was determined considering different scenarios, mainly volatile organic compounds/NO x (VOC/NO x ) ratios, and typical atmospheric conditions for the city of Rio de Janeiro, where more than 36% of the urbanized area is covered by vegetation. Ozone isopleths and incremental reactivity coefficients (IR) were evaluated to understand the direct contribution of isoprene to ground-level ozone formation and the negative impact of anthropogenic NO x emissions on the natural atmospheric balance. Although isoprene accounted for only 2.7% of the total VOC mass, excluding the isoprene concentration from the model reduced the maximum ozone value by 14.1%. The calculated IR coefficient (grams of O 3 formed per gram of added isoprene) was 2.2 for a VOC/NO x ratio of 8.86.

Electron impact vibrational excitation of carbon monoxide in the upper atmospheres of Mars and Venus

NASA Astrophysics Data System (ADS)

Campbell, L.; Allan, M.; Brunger, M. J.

2011-09-01

Infrared emission from CO in the upper atmospheres of Mars, Venus and several other planets is a subject of current theoretical and experimental interest. Electron impact excitation makes a contribution that has not been included in previous studies. Given this, and recent new measurements of absolute cross sections for low-energy electron impact excitation of the vibrational levels of the ground state of CO, results from calculations are presented showing the contribution of electron impact relative to emissions by other mechanisms. It is demonstrated that emissions due to the impact of thermal, photo- and auroral electrons are generally small compared to sunlight-driven (fluorescence and photolysis) emissions, but with some exceptions. It is also shown that thermal-electron emissions may dominate over other processes at nighttime at Mars and that auroral emissions certainly do so. While measurements and other calculations do not appear to be available for Venus, the volume emission rates presented should be valuable in planning such measurements.

Uptake of Alkylamines on Dicarboxylic Acids Relevant to Secondary Organic Aerosol Formation

NASA Astrophysics Data System (ADS)

Marrero-Ortiz, W.; Secrest, J.; Zhang, R.

2017-12-01

Aerosols play a critical role in climate directly by scattering and absorbing solar radiation, and indirectly by functioning as cloud condensation nuclei (CCN); both represent the largest uncertainties in climate predictions. New particle formation contributes significantly to CCN production; however, the mechanisms related to particle nucleation and growth processes are not well understood. Organic acids are atmospherically abundant, and their neutralization by low molecular weight amines may result in the formation of stable low volatility aminium salt products contributing to the growth of secondary organic aerosols and even the alteration of the aerosol properties. The acid-base neutralization of particle phase succinic acid and tartaric acid by low molecular weight aliphatic amines, i.e. methylamine, dimethylamine, and trimethylamine, has been investigated by employing a low-pressure fast flow reactor at 298K with an ion drift - chemical ionization mass spectrometer (ID-CIMS). The heterogeneous uptake is time dependent and influenced by organic acids functionality, alkylamines basicity, and steric effect. The implications of our results to atmospheric nanoparticle growth will be discussed.

Role of excited N2 in the production of nitric oxide

NASA Astrophysics Data System (ADS)

Campbell, L.; Cartwright, D. C.; Brunger, M. J.

2007-08-01

Excited N2 plays a role in a number of atmospheric processes, including auroral and dayglow emissions, chemical reactions, recombination of free electrons, and the production of nitric oxide. Electron impact excitation of N2 is followed by radiative decay through a series of excited states, contributing to auroral and dayglow emissions. These processes are intertwined with various chemical reactions and collisional quenching involving the excited and ground state vibrational levels. Statistical equilibrium and time step atmospheric models are used to predict N2 excited state densities and emissions (as a test against previous models and measurements) and to investigate the role of excited nitrogen in the production of nitric oxide. These calculations predict that inclusion of the reaction N2[A3Σu +] + O, to generate NO, produces an increase by a factor of up to three in the calculated NO density at some altitudes.

Preface: Current perspectives in modelling, monitoring, and predicting geophysical fluid dynamics

NASA Astrophysics Data System (ADS)

Mancho, Ana M.; Hernández-García, Emilio; López, Cristóbal; Turiel, Antonio; Wiggins, Stephen; Pérez-Muñuzuri, Vicente

2018-02-01

The third edition of the international workshop Nonlinear Processes in Oceanic and Atmospheric Flows was held at the Institute of Mathematical Sciences (ICMAT) in Madrid from 6 to 8 July 2016. The event gathered oceanographers, atmospheric scientists, physicists, and applied mathematicians sharing a common interest in the nonlinear dynamics of geophysical fluid flows. The philosophy of this meeting was to bring together researchers from a variety of backgrounds into an environment that favoured a vigorous discussion of concepts across different disciplines. The present Special Issue on Current perspectives in modelling, monitoring, and predicting geophysical fluid dynamics contains selected contributions, mainly from attendants of the workshop, providing an updated perspective on modelling aspects of geophysical flows as well as issues on prediction and assimilation of observational data and novel tools for describing transport and mixing processes in these contexts. More details on these aspects are discussed in this preface.

Observations of Titanium, Aluminum and Magnesium in the Lunar Exosphere by LADEE UVS

NASA Technical Reports Server (NTRS)

Colaprete, A.; Wooden, D.; Cook, A.; Shirley, M.; Sarantos, M.

2016-01-01

The Lunar Atmosphere and Dust Environment Explorer (LADEE) was an orbital lunar science mission designed to address the goals of the 2003 National Research Council decadal survey, the Lunar Exploration Analysis Group Roadmap, and the "Scientific Context for Exploration of the Moon" (SCEM) report, and has been recommended for execution by the 2011 Planetary Missions Decadal Survey. The LADEE mission goal was to determine the composition of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions. It will monitor variations in known gasses, such as sodium, potassium, argon and helium, and will search for other, as-yet-undetected gasses of both lunar and extra-lunar origin. Another goal of LADEE was to determine whether dust is present in the lunar exosphere, and reveal the processes that contribute to its sources and variability.

Oxygen-assisted multipass cutting of carbon fiber reinforced plastics with ultra-short laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kononenko, T. V.; Komlenok, M. S.; Konov, V. I.

Deep multipass cutting of bidirectional and unidirectional carbon fiber reinforced plastics (CFRP) with picosecond laser pulses was investigated in different static atmospheres as well as with the assistance of an oxygen or nitrogen gas flow. The ablation rate was determined as a function of the kerf depth and the resulting heat affected zone was measured. An assisting oxygen gas flow is found to significantly increase the cutting productivity, but only in deep kerfs where the diminished evaporative ablation due to the reduced laser fluence reaching the bottom of the kerf does not dominate the contribution of reactive etching anymore. Oxygen-supportedmore » cutting was shown to also solve the problem that occurs when cutting the CFRP parallel to the fiber orientation where a strong deformation and widening of the kerf, which temporarily slows down the process speed, is revealed to be typical for processing in standard air atmospheres.« less

Insights into Aqueous-phase processing through Comparison of the Organic Chemical Composition of Atmospheric Particles and Cloud Water in the Southeast United States

NASA Astrophysics Data System (ADS)

Boone, E.; Laskin, J.; Laskin, A.; Wirth, C.; Shepson, P. B.; Stirm, B. H.; Pratt, K.

2014-12-01

Organic compounds comprise a significant mass fraction of submicron atmospheric particles with considerable contribution from secondary organic aerosol (SOA), a large fraction of which is formed from the oxidation of biogenic volatile organic compounds. Aqueous-phase reactions in particles and cloud droplets are suggested to increase SOA mass and change the chemical composition the particles following cloud evaporation. Aqueous-phase processing may also explain discrepancies between measurements and models. To gain a better understanding of these processes, cloud water and below-cloud atmospheric particles were collected onboard a research aircraft during the Southeast Oxidants and Aerosol Study (SOAS) over Alabama in June 2013. Nanospray desorption electrospray ionization (nano-DESI) and direct electrospray ionization (ESI) coupled with high resolution mass spectrometry were utilized to compare the organic molecular composition of the particle and cloud water samples, respectively. Several hundred unique compounds have been identified in the particle and cloud water samples, allowing possible aqueous-phase reactions to be examined. Hydrolysis of organosulfate compounds, aqueous-phase formation of nitrogen-containing compounds, and possible fragmentation of oligomeric compounds will be discussed, with comparisons to previous laboratory studies. This study provides insights into aqueous-phase reactions in ambient cloud droplets.

Water from air: An overlooked source of moisture in arid and semiarid regions

USGS Publications Warehouse

McHugh, Theresa; Morrissey, Ember M.; Reed, Sasha C.; Hungate, Bruce A.; Schwartz, Egbert

2015-01-01

Water drives the functioning of Earth’s arid and semiarid lands. Drylands can obtain water from sources other than precipitation, yet little is known about how non-rainfall water inputs influence dryland communities and their activity. In particular, water vapor adsorption – movement of atmospheric water vapor into soil when soil air is drier than the overlying air – likely occurs often in drylands, yet its effects on ecosystem processes are not known. By adding 18O-enriched water vapor to the atmosphere of a closed system, we documented the conversion of water vapor to soil liquid water across a temperature range typical of arid ecosystems. This phenomenon rapidly increased soil moisture and stimulated microbial carbon (C) cycling, and the flux of water vapor to soil had a stronger impact than temperature on microbial activity. In a semiarid grassland, we also observed that non-rainfall water inputs stimulated microbial activity and C cycling. Together these data suggest that, during rain-free periods, atmospheric moisture in drylands may significantly contribute to variation in soil water content, thereby influencing ecosystem processes. The simple physical process of adsorption of water vapor to soil particles, forming liquid water, represents an overlooked but potentially important contributor to C cycling in drylands.

The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engel, Anja; Bange, Hermann W.; Cunliffe, Michael

Despite the huge extent of the ocean’s surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean’s surface, in particular involvingmore » the SML as an important and determinant interface, could therefore provide an essential contribution to the reduction of uncertainties regarding ocean-climate feedbacks. This review identifies gaps in our current knowledge of the SML and highlights a need to develop a holistic and mechanistic understanding of the diverse biological, chemical, and physical processes occurring at the ocean-atmosphere interface. We advocate the development of strong interdisciplinary expertise and collaboration in order to bridge between ocean and atmospheric sciences. Although this will pose significant methodological challenges, such an initiative would represent a new role model for interdisciplinary research in Earth System sciences.« less

The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer

DOE PAGES

Engel, Anja; Bange, Hermann W.; Cunliffe, Michael; ...

2017-05-30

Despite the huge extent of the ocean’s surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean’s surface, in particular involvingmore » the SML as an important and determinant interface, could therefore provide an essential contribution to the reduction of uncertainties regarding ocean-climate feedbacks. This review identifies gaps in our current knowledge of the SML and highlights a need to develop a holistic and mechanistic understanding of the diverse biological, chemical, and physical processes occurring at the ocean-atmosphere interface. We advocate the development of strong interdisciplinary expertise and collaboration in order to bridge between ocean and atmospheric sciences. Although this will pose significant methodological challenges, such an initiative would represent a new role model for interdisciplinary research in Earth System sciences.« less

Source attribution using FLEXPART and carbon monoxide emission inventories for the IAGOS In-situ Observation database

NASA Astrophysics Data System (ADS)

Fontaine, Alain; Sauvage, Bastien; Pétetin, Hervé; Auby, Antoine; Boulanger, Damien; Thouret, Valerie

2016-04-01

Since 1994, the IAGOS program (In-Service Aircraft for a Global Observing System http://www.iagos.org) and its predecessor MOZAIC has produced in-situ measurements of the atmospheric composition during more than 46000 commercial aircraft flights. In order to help analyzing these observations and further understanding the processes driving their evolution, we developed a modelling tool SOFT-IO quantifying their source/receptor link. We improved the methodology used by Stohl et al. (2003), based on the FLEXPART plume dispersion model, to simulate the contributions of anthropogenic and biomass burning emissions from the ECCAD database (http://eccad.aeris-data.fr) to the measured carbon monoxide mixing ratio along each IAGOS flight. Thanks to automated processes, contributions are simulated for the last 20 days before observation, separating individual contributions from the different source regions. The main goal is to supply add-value products to the IAGOS database showing pollutants geographical origin and emission type. Using this information, it may be possible to link trends in the atmospheric composition to changes in the transport pathways and to the evolution of emissions. This tool could be used for statistical validation as well as for inter-comparisons of emission inventories using large amounts of data, as Lagrangian models are able to bring the global scale emissions down to a smaller scale, where they can be directly compared to the in-situ observations from the IAGOS database.

The Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission

NASA Technical Reports Server (NTRS)

Spremo, Stevan; Turner, Mark; Caffrey, Robert T.; Hine, Butler Preston

2010-01-01

The Lunar Atmosphere and Dust Environment Explorer (LADEE) is a Lunar science orbiter mission currently under development to address the goals of the National Research Council decadal surveys and the recent "Scientific Context for Exploration of the Moon" (SCEM) [1] report to study the pristine state of the lunar atmosphere and dust environment prior to significant human activities. LADEE will determine the composition of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions. LADEE will also determine whether dust is present in the lunar exosphere, and reveal the processes that contribute to its sources and variability. These investigations are relevant to our understanding of surface boundary exospheres and dust processes throughout the solar system, address questions regarding the origin and evolution of lunar volatiles, and have potential implications for future exploration activities. LADEE employs a high heritage science instrument payload including a neutral mass spectrometer, ultraviolet spectrometer, and dust sensor. In addition to the science payloads, LADEE will fly a laser communications system technology demonstration that could provide a building block for future space communications architectures. LADEE is an important component in NASA's portfolio of near-term lunar missions, addressing objectives that are currently not covered by other U.S. or international efforts, and whose observations must be conducted before large-scale human or robotic activities irrevocably perturb the tenuous and fragile lunar atmosphere. LADEE will also demonstrate the effectiveness of a low-cost, rapid-development program utilizing a modular bus design launched on the new Minotaur V launch vehicle. Once proven, this capability could enable future lunar missions in a highly cost constrained environment. This paper describes the LADEE objectives, mission design, and technical approach.

Variability and Quasi-Decadal Changes in the Methane Budget over the Period 2000-2012

NASA Technical Reports Server (NTRS)

Saunois, Marielle; Bousquet, Philippe; Poulter, Ben; Peregon, Anna; Ciais, Philippe; Canadell, Josep G.; Dlugokencky, Edward J.; Etiope, Giuseppe; Bastviken, David; Houweling, Sander;

Variability and quasi-decadal changes in the methane budget over the period 2000-2012

NASA Astrophysics Data System (ADS)

Saunois, Marielle; Bousquet, Philippe; Poulter, Ben; Peregon, Anna; Ciais, Philippe; Canadell, Josep G.; Dlugokencky, Edward J.; Etiope, Giuseppe; Bastviken, David; Houweling, Sander; Janssens-Maenhout, Greet; Tubiello, Francesco N.; Castaldi, Simona; Jackson, Robert B.; Alexe, Mihai; Arora, Vivek K.; Beerling, David J.; Bergamaschi, Peter; Blake, Donald R.; Brailsford, Gordon; Bruhwiler, Lori; Crevoisier, Cyril; Crill, Patrick; Covey, Kristofer; Frankenberg, Christian; Gedney, Nicola; Höglund-Isaksson, Lena; Ishizawa, Misa; Ito, Akihiko; Joos, Fortunat; Kim, Heon-Sook; Kleinen, Thomas; Krummel, Paul; Lamarque, Jean-François; Langenfelds, Ray; Locatelli, Robin; Machida, Toshinobu; Maksyutov, Shamil; Melton, Joe R.; Morino, Isamu; Naik, Vaishali; O'Doherty, Simon; Parmentier, Frans-Jan W.; Patra, Prabir K.; Peng, Changhui; Peng, Shushi; Peters, Glen P.; Pison, Isabelle; Prinn, Ronald; Ramonet, Michel; Riley, William J.; Saito, Makoto; Santini, Monia; Schroeder, Ronny; Simpson, Isobel J.; Spahni, Renato; Takizawa, Atsushi; Thornton, Brett F.; Tian, Hanqin; Tohjima, Yasunori; Viovy, Nicolas; Voulgarakis, Apostolos; Weiss, Ray; Wilton, David J.; Wiltshire, Andy; Worthy, Doug; Wunch, Debra; Xu, Xiyan; Yoshida, Yukio; Zhang, Bowen; Zhang, Zhen; Zhu, Qiuan

2017-09-01

Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH4) budget over 2000-2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH4 emissions. The GCP dataset integrates results from top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models (including process-based models for estimating land surface emissions and atmospheric chemistry), inventories of anthropogenic emissions, and data-driven approaches. The annual global methane emissions from top-down studies, which by construction match the observed methane growth rate within their uncertainties, all show an increase in total methane emissions over the period 2000-2012, but this increase is not linear over the 13 years. Despite differences between individual studies, the mean emission anomaly of the top-down ensemble shows no significant trend in total methane emissions over the period 2000-2006, during the plateau of atmospheric methane mole fractions, and also over the period 2008-2012, during the renewed atmospheric methane increase. However, the top-down ensemble mean produces an emission shift between 2006 and 2008, leading to 22 [16-32] Tg CH4 yr-1 higher methane emissions over the period 2008-2012 compared to 2002-2006. This emission increase mostly originated from the tropics, with a smaller contribution from mid-latitudes and no significant change from boreal regions. The regional contributions remain uncertain in top-down studies. Tropical South America and South and East Asia seem to contribute the most to the emission increase in the tropics. However, these two regions have only limited atmospheric measurements and remain therefore poorly constrained. The sectorial partitioning of this emission increase between the periods 2002-2006 and 2008-2012 differs from one atmospheric inversion study to another. However, all top-down studies suggest smaller changes in fossil fuel emissions (from oil, gas, and coal industries) compared to the mean of the bottom-up inventories included in this study. This difference is partly driven by a smaller emission change in China from the top-down studies compared to the estimate in the Emission Database for Global Atmospheric Research (EDGARv4.2) inventory, which should be revised to smaller values in a near future. We apply isotopic signatures to the emission changes estimated for individual studies based on five emission sectors and find that for six individual top-down studies (out of eight) the average isotopic signature of the emission changes is not consistent with the observed change in atmospheric 13CH4. However, the partitioning in emission change derived from the ensemble mean is consistent with this isotopic constraint. At the global scale, the top-down ensemble mean suggests that the dominant contribution to the resumed atmospheric CH4 growth after 2006 comes from microbial sources (more from agriculture and waste sectors than from natural wetlands), with an uncertain but smaller contribution from fossil CH4 emissions. In addition, a decrease in biomass burning emissions (in agreement with the biomass burning emission databases) makes the balance of sources consistent with atmospheric 13CH4 observations. In most of the top-down studies included here, OH concentrations are considered constant over the years (seasonal variations but without any inter-annual variability). As a result, the methane loss (in particular through OH oxidation) varies mainly through the change in methane concentrations and not its oxidants. For these reasons, changes in the methane loss could not be properly investigated in this study, although it may play a significant role in the recent atmospheric methane changes as briefly discussed at the end of the paper.

Indian Ocean warming during 1958-2004 simulated by a climate system model and its mechanism

NASA Astrophysics Data System (ADS)

Dong, Lu; Zhou, Tianjun; Wu, Bo

2014-01-01

The mechanism responsible for Indian Ocean Sea surface temperature (SST) basin-wide warming trend during 1958-2004 is studied based on both observational data analysis and numerical experiments with a climate system model FGOALS-gl. To quantitatively estimate the relative contributions of external forcing (anthropogenic and natural forcing) and internal variability, three sets of numerical experiments are conducted, viz. an all forcing run forced by both anthropogenic forcing (greenhouse gases and sulfate aerosols) and natural forcing (solar constant and volcanic aerosols), a natural forcing run driven by only natural forcing, and a pre-industrial control run. The model results are compared to the observations. The results show that the observed warming trend during 1958-2004 (0.5 K (47-year)-1) is largely attributed to the external forcing (more than 90 % of the total trend), while the residual is attributed to the internal variability. Model results indicate that the anthropogenic forcing accounts for approximately 98.8 % contribution of the external forcing trend. Heat budget analysis shows that the surface latent heat flux due to atmosphere and surface longwave radiation, which are mainly associated with anthropogenic forcing, are in favor of the basin-wide warming trend. The basin-wide warming is not spatially uniform, but with an equatorial IOD-like pattern in climate model. The atmospheric processes, oceanic processes and climatological latent heat flux together form an equatorial IOD-like warming pattern, and the oceanic process is the most important in forming the zonal dipole pattern. Both the anthropogenic forcing and natural forcing result in easterly wind anomalies over the equator, which reduce the wind speed, thereby lead to less evaporation and warmer SST in the equatorial western basin. Based on Bjerknes feedback, the easterly wind anomalies uplift the thermocline, which is unfavorable to SST warming in the eastern basin, and contribute to SST warming via deeper thermocline in the western basin. The easterly anomalies also drive westward anomalous equatorial currents, against the eastward climatology currents, which is in favor of the SST warming in the western basin via anomalous warm advection. Therefore, both the atmospheric and oceanic processes are in favor of the IOD-like warming pattern formation over the equator.

Investigation of Processes Controlling Mercury Cycling at Midlatitudinal Marine and Inland Sites: Improvements and Applications of A Mercury Box Model

NASA Astrophysics Data System (ADS)

ye, Z.

2013-12-01

Mercury (Hg) is a hazardous pollutant due to the bioaccumulation in food chain. It is emitted to the atmosphere primarily as elemental form, and the long lifetime of which allows global transport. Oxidation of gaseous elemental mercury (GEM) generates reactive gaseous mercury (RGM) which plays an important role in the atmospheric mercury cycle by enhancing the rate of mercury deposition to ecosystem. The present study aimed to investigate the midlatitudinal atmospheric Hg cycling. To achieve that, a mercury chemistry box model was improved by employing the most up-to-date kinetic data for gaseous and aqueous reactions, and was applied to summertime clear sky conditions at three specific sites: Appledore Island (marine site), Thompson Farm (coastal site), and Pack Monadnock (inland site). The model was evaluated using observational data of RGM and pHg (particulate mercury) concentrations from these sites. The simulation results for all three sites showed that HgO, which is produced from oxidation of GEM by O3 and OH, contributed the most (>82%) to the total RGM production. Even in the marine boundary layer, halogen species (mainly Br) only contributed less than 12% to total RGM. The importance of reactions in most updated halogen chemistry has been evaluated. Gas and particle partitioning played an important role in coastal and inland environments. Some abnormally high RGM peaks were found at Appledore Island which may be explained by transport and air-sea exchange. Specific reactions and other processes controlling the diurnal cycles of RGM and pHg at the three sites are still being investigated.

Research Activities for the DORIS Contribution to the Next International Terrestrial Reference Frame

NASA Technical Reports Server (NTRS)

Soudarin, L.; Moreaux, G.; Lemoine, F.; Willis, P.; Stepanek, P.; Otten, M.; Govind, R.; Kuzin, S.; Ferrage, P.

2012-01-01

For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include (i) assessing the contribution of the new DORIS satellites, Jason-2 and Cryosat2 (2008-2011), (ii) individually analyzing the DORIS satellite contributions to geocenter and scale, and (iii) improving orbit dynamics (atmospheric loading effects, satellite surface force modeling. . . ). We report on the preliminary results from these research activities, review the status of the IDS combination which is now routinely generated from the contributions of the IDS analysis centers, and discuss the prospects for continued improvement in the DORIS contribution to the next international reference frame.

Development and Performance of the Modularized, High-performance Computing and Hybrid-architecture Capable GEOS-Chem Chemical Transport Model

NASA Astrophysics Data System (ADS)

Long, M. S.; Yantosca, R.; Nielsen, J.; Linford, J. C.; Keller, C. A.; Payer Sulprizio, M.; Jacob, D. J.

2014-12-01

The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been reengineered to serve as a platform for a range of computational atmospheric chemistry science foci and applications. Development included modularization for coupling to general circulation and Earth system models (ESMs) and the adoption of co-processor capable atmospheric chemistry solvers. This was done using an Earth System Modeling Framework (ESMF) interface that operates independently of GEOS-Chem scientific code to permit seamless transition from the GEOS-Chem stand-alone serial CTM to deployment as a coupled ESM module. In this manner, the continual stream of updates contributed by the CTM user community is automatically available for broader applications, which remain state-of-science and directly referenceable to the latest version of the standard GEOS-Chem CTM. These developments are now available as part of the standard version of the GEOS-Chem CTM. The system has been implemented as an atmospheric chemistry module within the NASA GEOS-5 ESM. The coupled GEOS-5/GEOS-Chem system was tested for weak and strong scalability and performance with a tropospheric oxidant-aerosol simulation. Results confirm that the GEOS-Chem chemical operator scales efficiently for any number of processes. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemical operator means that the relative cost goes down with increasing number of processes, making fine-scale resolution simulations possible.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longo, Amelia F.; Feng, Yan; Lai, Barry

Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet-chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated the aerosol iron in Mediterranean samples. In Atlantic samples, iron(II and III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation statemore » became more reduced, and aerosol acidity increased. As a result, atmospheric processing including acidic reactions and photoreduction likely influence the form of iron minerals and oxidation state in Saharan dust aerosols and contribute to increases in aerosol-iron solubility.« less

Process Upsets Involving Trace Contaminant Control Systems

NASA Technical Reports Server (NTRS)

Graf, John C.; Perry, Jay; Wright, John; Bahr, Jim

2000-01-01

Paradoxically, trace contaminant control systems that suffer unexpected upsets and malfunctions can release hazardous gaseous contaminants into a spacecraft cabin atmosphere causing potentially serious toxicological problems. Trace contaminant control systems designed for spaceflight typically employ a combination of adsorption beds and catalytic oxidation reactors to remove organic and inorganic trace contaminants from the cabin atmosphere. Interestingly, the same design features and attributes which make these systems so effective for purifying a spacecraft's atmosphere can also make them susceptible to system upsets. Cabin conditions can be contributing causes of phenomena such as adsorbent "rollover" and catalyst poisoning can alter a systems performance and in some in stances release contamination into the cabin. Evidence of these phenomena has been observed both in flight and during ground-based tests. The following discussion describes specific instances of system upsets found in trace contaminant control systems, groups these specific upsets into general hazard classifications, and recommends ways to minimize these hazards.

Precipitation Recycling

NASA Technical Reports Server (NTRS)

Eltahir, Elfatih A. B.; Bras, Rafael L.

1996-01-01

The water cycle regulates and reflects natural variability in climate at the regional and global scales. Large-scale human activities that involve changes in land cover, such as tropical deforestation, are likely to modify climate through changes in the water cycle. In order to understand, and hopefully be able to predict, the extent of these potential global and regional changes, we need first to understand how the water cycle works. In the past, most of the research in hydrology focused on the land branch of the water cycle, with little attention given to the atmospheric branch. The study of precipitation recycling which is defined as the contribution of local evaporation to local precipitation, aims at understanding hydrologic processes in the atmospheric branch of the water cycle. Simply stated, any study on precipitation recycling is about how the atmospheric branch of the water cycle works, namely, what happens to water vapor molecules after they evaporate from the surface, and where will they precipitate?

Atmospheric Prebiotic Chemistry and Organic Hazes

PubMed Central

Trainer, Melissa G.

2013-01-01

Earth’s atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of prebiotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer – if formed – would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere. PMID:24143126

Atmospheric Prebiotic Chemistry and Organic Hazes.

PubMed

Trainer, Melissa G

2013-08-01

Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of prebiotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

Atmospheric Prebiotic Chemistry and Organic Hazes

NASA Technical Reports Server (NTRS)

Trainer, Melissa G.

2012-01-01

Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of pre biotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

Water-leaving contribution to polarized radiation field over ocean.

PubMed

Zhai, Peng-Wang; Knobelspiesse, Kirk; Ibrahim, Amir; Franz, Bryan A; Hu, Yongxiang; Gao, Meng; Frouin, Robert

2017-08-07

The top-of-atmosphere (TOA) radiation field from a coupled atmosphere-ocean system (CAOS) includes contributions from the atmosphere, surface, and water body. Atmospheric correction of ocean color imagery is to retrieve water-leaving radiance from the TOA measurement, from which ocean bio-optical properties can be obtained. Knowledge of the absolute and relative magnitudes of water-leaving signal in the TOA radiation field is important for designing new atmospheric correction algorithms and developing retrieval algorithms for new ocean biogeochemical parameters. In this paper we present a systematic sensitivity study of water-leaving contribution to the TOA radiation field, from 340 nm to 865 nm, with polarization included. Ocean water inherent optical properties are derived from bio-optical models for two kinds of waters, one dominated by phytoplankton (PDW) and the other by non-algae particles (NDW). In addition to elastic scattering, Raman scattering and fluorescence from dissolved organic matter in ocean waters are included. Our sensitivity study shows that the polarized reflectance is minimized for both CAOS and ocean signals in the backscattering half plane, which leads to numerical instability when calculating water leaving relative contribution, the ratio between polarized water leaving and CAOS signals. If the backscattering plane is excluded, the water-leaving polarized signal contributes less than 9% to the TOA polarized reflectance for PDW in the whole spectra. For NDW, the polarized water leaving contribution can be as much as 20% in the wavelength range from 470 to 670 nm. For wavelengths shorter than 452 nm or longer than 865 nm, the water leaving contribution to the TOA polarized reflectance is in general smaller than 5% for NDW. For the TOA total reflectance, the water-leaving contribution has maximum values ranging from 7% to 16% at variable wavelengths from 400 nm to 550 nm from PDW. The water leaving contribution to the TOA total reflectance can be as large as 35% for NDW, which is in general peaked at 550 nm. Both the total and polarized reflectances from water-leaving contributions approach zero in the ultraviolet and near infrared bands. These facts can be used as constraints or guidelines when estimating the water leaving contribution to the TOA reflectance for new atmospheric correction algorithms for ocean color imagery.

Water-Leaving Contribution to Polarized Radiation Field Over Ocean

NASA Technical Reports Server (NTRS)

Zhai, Peng-Wang; Knobelspiesse, Kirk D.; Ibrahim, Amir; Franz, Bryan A.; Hu, Yongxiang; Gao, Meng; Frouin, Robert

2017-01-01

The top-of-atmosphere (TOA) radiation field from a coupled atmosphere-ocean system (CAOS) includes contributions from the atmosphere, surface, and water body. Atmo-spheric correction of ocean color imagery is to retrieve water-leaving radiance from the TOA measurement, from which ocean bio-optical properties can be obtained. Knowledge of the ab-solute and relative magnitudes of water-leaving signal in the TOA radiation field is important for designing new atmospheric correction algorithms and developing retrieval algorithms for new ocean biogeochemical parameters. In this paper we present a systematic sensitivity study of water-leaving contribution to the TOA radiation field, from 340 nm to 865 nm, with polarization included. Ocean water inherent optical properties are derived from bio-optical models for two kinds of waters, one dominated by phytoplankton (PDW) and the other by non-algae particles (NDW). In addition to elastic scattering, Raman scattering and fluorescence from dissolved organic matter in ocean waters are included. Our sensitivity study shows that the polarized reflectance is minimized for both CAOS and ocean signals in the backscattering half plane, which leads to numerical instability when calculating water leaving relative contribution, the ratio between polarized water leaving and CAOS signals. If the backscattering plane is excluded, the water-leaving polarized signal contributes less than 9% to the TOA polarized reflectance for PDW in the whole spectra. For NDW, the polarized water leaving contribution can be as much as 20% in the wavelength range from 470 to 670 nm. For wavelengths shorter than 452 nm or longer than 865 nm, the water leaving contribution to the TOA polarized reflectance is in general smaller than 5% for NDW. For the TOA total reflectance, the water-leaving contribution has maximum values ranging from 7% to 16% at variable wavelengths from 400 nm to 550 nm from PDW. The water leaving contribution to the TOA total reflectance can be as large as 35%for NDW, which is in general peaked at 550 nm. Both the total and polarized reflectances from water-leaving contributions approach zero in the ultraviolet and near infrared bands. These facts can be used as constraints or guidelines when estimating the water leaving contribution to the TOA reflectance for new atmospheric correction algorithms for ocean color imagery.

Miniature X-Ray Solar Spectrometer: A Science-Oriented, University 3U CubeSat

NASA Technical Reports Server (NTRS)

Mason, James P.; Woods, Thomas N.; Caspi, Amir; Chamberlin, Phillip C.; Moore, Christopher; Jones, Andrew; Kohnert, Rick; Li, Xinlin; Palo, Scott; Solomon, Stanley C.

2016-01-01

The miniature x-ray solar spectrometer is a three-unit CubeSat developed at the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. Over 40 students contributed to the project with professional mentorship and technical contributions from professors in the Aerospace Engineering Sciences Department at University of Colorado, Boulder and from Laboratory for Atmospheric and Space Physics scientists and engineers. The scientific objective of the miniature x-ray solar spectrometer is to study processes in the dynamic sun, from quiet sun to solar flares, and to further understand how these changes in the sun influence the Earth's atmosphere by providing unique spectral measurements of solar soft x-rays. The enabling technology providing the advanced solar soft x-ray spectral measurements is the Amptek X123, a commercial off-the-shelf silicon drift detector. The Amptek X123 has a low mass (approx. 324 g after modification), modest power consumption (approx. 2.50 W), and small volume (6.86 x 9.91 x 2.54 cm), making it ideal for a CubeSat. This paper provides an overview of the miniature x-ray solar spectrometer mission: the science objectives, project history, subsystems, and lessons learned, which can be useful for the small-satellite community.

Contribution of Organic Material to the Stable Isotope Composition of Some Terrestrial Carbonates as Analogs for Martian Processes

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Gibson, Everett K., Jr.; Bissada, K. K.

2005-01-01

Understanding the isotopic geochemistry of terrestrial carbonate formation is essential to understanding the evolution of the Martian atmosphere, hydrosphere, and potential biosphere. Carbonate minerals, in particular, are important secondary minerals for interpreting past aqueous environments, as illustrated by the carbonates present in ALH84001 [1]. Models for the history of Mars suggest that the planet was warmer, wetter, and possessed a greater atmospheric pressure within the first billion years as compared to present conditions [2],[3],[4], and likely had an active hydrologic cycle. Morse and Marion [5] point out that associated with this hydrologic cycle would be the active chemical weathering of silicate minerals and thus consumption of atmospheric CO2 and deposition of carbonate and silica. It is during this warmer and wetter period of Martian history that surface and/or near-surface conditions would be most favorable for harboring possible microbiological life. Carbonates within ALH84001 offer evidence that fluids were present at 3.9 Gy on Mars [6]. A more through understanding of the effects of aqueous weathering and the potential contribution of organic compounds on the isotopic composition of Martian carbonate minerals can be gained by studying some terrestrial occurrences of carbonate rocks.

Quantification of an atmospheric nucleation and growth process as a single source of aerosol particles in a city

NASA Astrophysics Data System (ADS)

Salma, Imre; Varga, Veronika; Németh, Zoltán

2017-12-01

Effects of a new aerosol particle formation (NPF) and particle diameter growth process as a single source of atmospheric particle number concentrations were evaluated and quantified on the basis of experimental data sets obtained from particle number size distribution measurements in the city centre and near-city background of Budapest for 5 years. Nucleation strength factors for a nucleation day (NSFNUC) and for a general day (NSFGEN) were derived separately for seasons and full years. The former characteristic represents the concentration increment of ultrafine (UF) particles specifically on nucleation days with respect to accumulation-mode (regional background) concentrations (particles with equivalent diameters of 100-1000 nm; N100-1000) due solely to the nucleation process. The latter factor expresses the contribution of nucleation to particle numbers on general days; thus, it represents a longer time interval such as season or year. The nucleation source had the largest effect on the concentrations around noon and early afternoon, as expected. During this time interval, it became the major source of particles in the near-city background. Nucleation increased the daily mean concentrations on nucleation days by mean factors of 2.3 and 1.58 in the near-city background and city centre, respectively. Its effect was largest in winter, which was explained by the substantially lower N100-1000 levels on nucleation days than those on non-nucleation days. On an annual timescale, 37 % of the UF particles were generated by nucleation in the near-city background, while NPF produced 13 % of UF particles in the city centre. The differences among the annual mean values, and among the corresponding seasonal mean values, were likely caused by the variability in controlling factors from year to year. The values obtained represent the lower limits of the contributions. The shares determined imply that NPF is a non-negligible or substantial source of particles in near-city background environments and even in city centres, where the vehicular road emissions usually prevail. Atmospheric residence time of nucleation-mode particles was assessed by a decay curve analysis, and a mean of 02:30 was obtained. The present study suggests that the health-related consequences of the atmospheric NPF and growth process in cities should also be considered in addition to its urban climate implications.

Contribution to the beam plasma material interactions during material processing with TEA CO2 laser radiation

NASA Astrophysics Data System (ADS)

Jaschek, Rainer; Konrad, Peter E.; Mayerhofer, Roland; Bergmann, Hans W.; Bickel, Peter G.; Kowalewicz, Roland; Kuttenberger, Alfred; Christiansen, Jens

1995-03-01

The TEA-CO2-laser (transversely excited atmospheric pressure) is a tool for the pulsed processing of materials with peak power densities up to 1010 W/cm2 and a FWHM of 70 ns. The interaction between the laser beam, the surface of the work piece and the surrounding atmosphere as well as gas pressure and the formation of an induced plasma influences the response of the target. It was found that depending on the power density and the atmosphere the response can take two forms. (1) No target modification due to optical break through of the atmosphere and therefore shielding of the target (air pressure above 10 mbar, depending on the material). (2) Processing of materials (air pressure below 10 mbar, depending on the material) with melting of metallic surfaces (power density above 0.5 109 W/cm2), hole formation (power density of 5 109 W/cm2) and shock hardening (power density of 3.5 1010 W/cm2). All those phenomena are usually linked with the occurrence of laser supported combustion waves and laser supported detonation waves, respectively for which the mechanism is still not completely understood. The present paper shows how short time photography and spatial and temporal resolved spectroscopy can be used to better understand the various processes that occur during laser beam interaction. The spectra of titanium and aluminum are observed and correlated with the modification of the target. If the power density is high enough and the gas pressure above a material and gas composition specific threshold, the plasma radiation shows only spectral lines of the background atmosphere. If the gas pressure is below this threshold, a modification of the target surface (melting, evaporation and solid state transformation) with TEA-CO2- laser pulses is possible and the material specific spectra is observed. In some cases spatial and temporal resolved spectroscopy of a plasma allows the calculation of electron temperatures by comparison of two spectral lines.

State of the Carbon Cycle - Consequences of Rising Atmospheric CO2

NASA Astrophysics Data System (ADS)

Moore, D. J.; Cooley, S. R.; Alin, S. R.; Brown, M. E.; Butman, D. E.; French, N. H. F.; Johnson, Z. I.; Keppel-Aleks, G.; Lohrenz, S. E.; Ocko, I.; Shadwick, E. H.; Sutton, A. J.; Potter, C. S.; Yu, R. M. S.

2016-12-01

The rise of atmospheric CO2, largely attributable to human activity through fossil fuel emissions and land-use change, has been dampened by carbon uptake by the ocean and terrestrial biosphere. We outline the consequences of this carbon uptake as direct and indirect effects on terrestrial and oceanic systems and processes for different regions of North America and the globe. We assess the capacity of these systems to continue to act as carbon sinks. Rising CO2 has decreased seawater pH; this process of ocean acidification has impacted some marine species and altered fundamental ecosystem processes with further effects likely. In terrestrial ecosystems, increased atmospheric CO2 causes enhanced photosynthesis, net primary production, and increased water-use efficiency. Rising CO2 may change vegetation composition and carbon storage, and widespread increases in water use efficiency likely influence terrestrial hydrology and biogeochemical cycling. Consequences for human populations include changes to ecosystem services including cultural activities surrounding land use, agricultural or harvesting practices. Commercial fish stocks have been impacted and crop production yields have been changed as a result of rising CO2. Ocean and terrestrial effects are contingent on, and feedback to, global climate change. Warming and modified precipitation regimes impact a variety of ecosystem processes, and the combination of climate change and rising CO2 contributes considerable uncertainty to forecasting carbon sink capacity in the ocean and on land. Disturbance regime (fire and insects) are modified with increased temperatures. Fire frequency and intensity increase, and insect lifecycles are disrupted as temperatures move out of historical norms. Changes in disturbance patterns modulate the effects of rising CO2 depending on ecosystem type, disturbance frequency, and magnitude of events. We discuss management strategies designed to limit the rise of atmospheric CO2 and reduce uncertainty in forecasts of decadal and centennial feedbacks of rising atmospheric CO2 on carbon storage.

State of the Carbon Cycle - Consequences of Rising Atmospheric CO2

NASA Technical Reports Server (NTRS)

Moore, David J.; Cooley, Sarah R.; Alin, Simone R.; Brown, Molly; Butman, David E.; French, Nancy H. F.; Johnson, Zackary I.; Keppel-Aleks; Lohrenz, Steven E.; Ocko, Ilissa;

A Digital Map From External Forcing to the Final Surface Warming Pattern and its Seasonal Cycle

NASA Astrophysics Data System (ADS)

Cai, M.

2015-12-01

Historically, only the thermodynamic processes (e.g., water vapor, cloud, surface albedo, and atmospheric lapse rate) that directly influence the top of the atmosphere (TOA) radiative energy flux balance are considered in climate feedback analysis. One of my recent research areas is to develop a new framework for climate feedback analysis that explicitly takes into consideration not only the thermodynamic processes that the directly influence the TOA radiative energy flux balance but also the local dynamical (e.g., evaporation, surface sensible heat flux, vertical convections etc) and non-local dynamical (large-scale horizontal energy transport) processes in aiming to explain the warming asymmetry between high and low latitudes, between ocean and land, and between the surface and atmosphere. In the last 5-6 years, we have developed a coupled atmosphere-surface climate feedback-response analysis method (CFRAM) as a new framework for estimating climate feedback and sensitivity in coupled general circulation models with a full physical parameterization package. In the CFRAM, the isolation of partial temperature changes due to an external forcing alone or an individual feedback is achieved by solving the linearized infrared radiation transfer model subject to individual energy flux perturbations (external or due to feedbacks). The partial temperature changes are addable and their sum is equal to the (total) temperature change (in the linear sense). The CFRAM is used to isolate the partial temperature changes due to the external forcing, due to water vapor feedback, clouds, surface albedo, local vertical convection, and non-local atmospheric dynamical feedbacks, as well as oceanic heat storage. It has been shown that seasonal variations in the cloud feedback, surface albedo feedback, and ocean heat storage/dynamics feedback, directly caused by the strong annual cycle of insolation, contribute primarily to the large seasonal variation of polar warming. Furthermore, the CO2 forcing, and water vapor and atmospheric dynamics feedbacks add to the maximum polar warming in fall/winter.

Exploring microphysical, radiative, dynamic and thermodynamic processes driving fog and low stratus clouds using ground-based Lidar and Radar measurements

NASA Astrophysics Data System (ADS)

Haeffelin, Martial

2016-04-01

Radiation fog formation is largely influenced by the chemical composition, size and number concentration of cloud condensation nuclei and by heating/cooling and drying/moistening processes in a shallow mixing layer near the surface. Once a fog water layer is formed, its development and dissipation become predominantly controlled by radiative cooling/heating, turbulent mixing, sedimentation and deposition. Key processes occur in the atmospheric surface layer, directly in contact with the soil and vegetation, and throughout the atmospheric column. Recent publications provide detailed descriptions of these processes for idealized cases using very high-resolution models and proper representation of microphysical processes. Studying these processes in real fog situations require atmospheric profiling capabilities to monitor the temporal evolution of key parameters at several heights (surface, inside the fog, fog top, free troposphere). This could be done with in-situ sensors flown on tethered balloons or drones, during dedicated intensive field campaigns. In addition Backscatter Lidars, Doppler Lidars, Microwave Radiometers and Cloud Doppler Radars can provide more continuous, yet precise monitoring of key parameters throughout the fog life cycle. The presentation will describe how Backscatter Lidars can be used to study the height and kinetics of aerosol activation into fog droplets. Next we will show the potential of Cloud Doppler Radar measurements to characterize the temporal evolution of droplet size, liquid water content, sedimentation and deposition. Contributions from Doppler Lidars and Microwave Radiometers will be discussed. This presentation will conclude on the potential to use Lidar and Radar remote sensing measurements to support operational fog nowcasting.

Triboelectrification of KCl and ZnS particles with applications to GJ1214b

NASA Astrophysics Data System (ADS)

Mendez, Joshua; Dufek, Josef

2017-10-01

When mobilized, granular materials become charged as individual grains undergo collisions and frictional interactions. On Earth, this process, known as triboelectrification, has been recognized in volcanic plumes and sandstorms (Kok & Lacks 2009 )(Cimarelli et al. 2014 ) (Méndez Harper & Dufek 2016 ). Yet, frictional charging almost certainly exists on other worlds in our own Solar System (such as Mars, the Moon, and Venus) as well as extra solar planets. Indeed, recent observations and numerical modeling have suggested that many exoplanets may have processes that lift large quantities of particles into their atmospheres (volcanic activity, for instance) (Hodosán et al. 2016 ) or maintain extensive condensed granular reservoirs in the form of clouds or hazes (Helling et al. 2013 )(Kreidberg et al. 2014 ) (Gao & Benneke 2016 ). On these worlds, triboelectric charging almost certainly contributes to their global electric circuits, providing a mechanism to generate lightning, to drive chemical processes in the atmospheres, and, perhaps, influence habitability. Yet, despite the high likelihood of granular electrification processes occurring on worlds beyond our Solar System, no experiments, to our knowledge, have been conducted to characterize the triboelectrification of materials expected to exist in the exoplanet atmospheres under appropriate conditions. To help close this knowledge-gap, we explore the electrification of potassium chloride and zinc sulfide, two substances possibly composing the clouds on super-Earth GJ1214b (Kreidberg et al. 2014 ) (Charnay et al. 2015 ) (Gao & Benneke 2016 ). We find that both materials become readily electrified when mobilized, attaining charge densities similar to those found on volcanic ash particles. Thus, if GJ1214b does indeed host salt clouds in its atmosphere, they are likely electrified and may be capable of producing lightning or corona discharge.

A multilinear regression methodology to analyze the effect of atmospheric and surface forcing on Arctic clouds

NASA Astrophysics Data System (ADS)

Boeke, R.; Taylor, P. C.; Li, Y.

2017-12-01

Arctic cloud amount as simulated in CMIP5 models displays large intermodel spread- models disagree on the processes important for cloud formation as well as the radiative impact of clouds. The radiative response to cloud forcing can be better assessed when the drivers of Arctic cloud formation are known. Arctic cloud amount (CA) is a function of both atmospheric and surface conditions, and it is crucial to separate the influences of unique processes to understand why the models are different. This study uses a multilinear regression methodology to determine cloud changes using 3 variables as predictors: lower tropospheric stability (LTS), 500-hPa vertical velocity (ω500), and sea ice concentration (SIC). These three explanatory variables were chosen because their effects on clouds can be attributed to unique climate processes: LTS is a thermodynamic indicator of the relationship between clouds and atmospheric stability, SIC determines the interaction between clouds and the surface, and ω500 is a metric for dynamical change. Vertical, seasonal profiles of necessary variables are obtained from the Coupled Model Intercomparison Project 5 (CMIP5) historical simulation, an ocean-atmosphere couple model forced with the best-estimate natural and anthropogenic radiative forcing from 1850-2005, and statistical significance tests are used to confirm the regression equation. A unique heuristic model will be constructed for each climate model and for observations, and models will be tested by their ability to capture the observed cloud amount and behavior. Lastly, the intermodel spread in Arctic cloud amount will be attributed to individual processes, ranking the relative contributions of each factor to shed light on emergent constraints in the Arctic cloud radiative effect.

Research in Neutrino Physics and Particle Astrophysics: Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kearns, Edward

The Boston University Neutrino Physics and Particle Astrophysics Group investigates the fundamental laws of particle physics using natural and man-made neutrinos and rare processes such as proton decay. The primary instrument for this research is the massive Super-Kamiokande (SK) water Cherenkov detector, operating since 1996 at the Kamioka Neutrino Observatory, one kilometer underground in a mine in Japan. We study atmospheric neutrinos from cosmic rays, which were first used to discover that neutrinos have mass, as recognized by the 2015 Nobel Prize in Physics. Our latest measurements with atmospheric neutrinos are giving valuable information, complementary to longbaseline experiments, on themore » ordering of massive neutrino states and as to whether neutrinos violate CP symmetry. We have studied a variety of proton decay modes, including the most frequently predicted modes such as p → e +π 0 and p → ν K +, as well as more exotic baryon number violating processes such as dinucleon decay and neutronantineutron oscillation. We search for neutrinos from dark matter annihilation or decay in the universe. Our group has made significant contributions to detector operation, particularly in the area of electronics. Most recently, we have contributed to planning for an upgrade to the SK detector by the addition of gadolinium to the water, which will enable efficient neutron capture detection.« less

Missing ozone-induced potential aerosol formation in a suburban deciduous forest

NASA Astrophysics Data System (ADS)

Nakayama, T.; Kuruma, Y.; Matsumi, Y.; Morino, Y.; Sato, K.; Tsurumaru, H.; Ramasamy, S.; Sakamoto, Y.; Kato, S.; Miyazaki, Y.; Mochizuki, T.; Kawamura, K.; Sadanaga, Y.; Nakashima, Y.; Matsuda, K.; Kajii, Y.

2017-12-01

As a new approach to investigating formation processes of secondary organic aerosol (SOA) in the atmosphere, ozone-induced potential aerosol formation was measured in summer at a suburban forest site surrounded by deciduous trees, near Tokyo, Japan. After passage through a reactor containing high concentrations of ozone, increases in total particle volume (average of 1.4 × 109 nm3/cm3, which corresponds to 17% that of pre-existing particles) were observed, especially during daytime. The observed aerosol formations were compared with the results of box model simulations using simultaneously measured concentrations of gaseous and particulate species. According to the model, the relative contributions of isoprene, monoterpene, and aromatic hydrocarbon oxidation to SOA formation in the reactor were 24, 21, and 55%, respectively. However, the model could explain, on average, only ∼40% of the observed particle formation, and large discrepancies between the observations and model were found, especially around noon and in the afternoon when the concentrations of isoprene and oxygenated volatile organic compounds were high. The results suggest a significant contribution of missing (unaccounted-for) SOA formation processes from identified and/or unidentified volatile organic compounds, especially those emitted during daytime. Further efforts should be made to explore and parameterize this missing SOA formation to assist in the improvement of atmospheric chemistry and climate models.

Investigation of diverse bacteria in cloud water at Mt. Tai, China.

PubMed

Xu, Caihong; Wei, Min; Chen, Jianmin; Sui, Xiao; Zhu, Chao; Li, Jiarong; Zheng, Lulu; Sui, Guodong; Li, Weijun; Wang, Wenxing; Zhang, Qingzhu; Mellouki, Abdelwahid

2017-02-15

Bacteria are abundant in atmospheric water phase with the potential to influence atmospheric processes and human health, yet relatively little information is known about the bacterial characteristics at high altitudes. Here we investigated the bacterial community by high throughput sequencing in 24 cloud water samples collected from September 26 to October 31, at the summit of Mt. Tai (36°15' N, 117°06' E, 1534m a.s.l) in China. Diverse bacterial population were identified and the gram-negative bacteria contributed the majority of total bacteria including Proteobacteria (81.6%) and Bacteroidetes (3.9%), followed by gram-positive bacteria Firmicutes (7.1%) and Actinobacteria (2.3%). These gram-negative taxa mainly inhabited in leaf-surface and cold environments. Meanwhile bacteria involved in the cloud condensation nuclei and ice nuclei formation were observed such as Sphingomonas (6.7%), Pseudomonas (4.1%), and Bacillus (1.1%). In addition, Sphingmonas was more active than that in daytime and participated in the cloud chemistry process. Meanwhile O 3 and SO 2 critically contributed to the variation of bacterial community. It is the first report on the bacterial community structure of cloud water over Asian area. Our results can serve as an important reference for environmental scientists, and biologists. Copyright © 2016. Published by Elsevier B.V.

On the Causes of Mid-Pliocene Warmth and Polar Amplification

NASA Technical Reports Server (NTRS)

Lunt, Daniel J.; Haywood, Alan M.; Schmidt, Gavin A.; Salzmann, Ulrich; Valdes, Paul J.; Dowsett, Harry J.; Loptson, Claire A.

2012-01-01

The mid-Pliocene (approximately 3 to 3.3 Ma ago), is a period of sustained global warmth in comparison to the late Quaternary (0 to approximately 1 Ma ago), and has potential to inform predictions of long-term future climate change. However, given that several processes potentially contributed, relatively little is understood about the reasons for the observed warmth, or the associated polar amplification. Here, using a modelling approach and a novel factorisation method, we assess the relative contributions to mid-Pliocene warmth from: elevated CO2, lowered orography, and vegetation and ice sheet changes. The results show that on a global scale, the largest contributor to mid-Pliocene warmth is elevated CO2. However, in terms of polar amplification, changes to ice sheets contribute significantly in the Southern Hemisphere, and orographic changes contribute significantly in the Northern Hemisphere. We also carry out an energy balance analysis which indicates that that on a global scale, surface albedo and atmospheric emmissivity changes dominate over cloud changes. We investigate the sensitivity of our results to uncertainties in the prescribed CO2 and orographic changes, to derive uncertainty ranges for the various contributing processes.

Mineral Dust Instantaneous Radiative Forcing in the Arctic

NASA Astrophysics Data System (ADS)

Kylling, A.; Groot Zwaaftink, C. D.; Stohl, A.

2018-05-01

Mineral dust sources at high and low latitudes contribute to atmospheric dust loads and dust deposition in the Arctic. With dust load estimates from Groot Zwaaftink et al. (https://doi.org/10.1002/2016JD025482), we quantify the mineral dust instantaneous radiative forcing (IRF) in the Arctic for the year 2012. The annual-mean top of the atmosphere IRF is 0.225 W/m2, with the largest contributions from dust transported from Asia south of 60°N and Africa. High-latitude (>60°N) dust sources contribute about 39% to top of the atmosphere IRF and have a larger impact (1 to 2 orders of magnitude) on IRF per emitted kilogram of dust than low-latitude sources. Mineral dust deposited on snow accounts for nearly all of the bottom of the atmosphere IRF of 0.135 W/m2. More than half of the bottom of the atmosphere IRF is caused by dust from high-latitude sources, indicating substantial regional climate impacts rarely accounted for in current climate models.

Biosphere model simulations of interannual variability in terrestrial 13C/12C exchange

NASA Astrophysics Data System (ADS)

van der Velde, I. R.; Miller, J. B.; Schaefer, K.; Masarie, K. A.; Denning, S.; White, J. W. C.; Tans, P. P.; Krol, M. C.; Peters, W.

2013-09-01

Previous studies suggest that a large part of the variability in the atmospheric ratio of 13CO2/12CO2originates from carbon exchange with the terrestrial biosphere rather than with the oceans. Since this variability is used to quantitatively partition the total carbon sink, we here investigate the contribution of interannual variability (IAV) in biospheric exchange to the observed atmospheric 13C variations. We use the Simple Biosphere - Carnegie-Ames-Stanford Approach biogeochemical model, including a detailed isotopic fractionation scheme, separate 12C and 13C biogeochemical pools, and satellite-observed fire disturbances. This model of 12CO2 and 13CO2 thus also produces return fluxes of 13CO2from its differently aged pools, contributing to the so-called disequilibrium flux. Our simulated terrestrial 13C budget closely resembles previously published model results for plant discrimination and disequilibrium fluxes and similarly suggests that variations in C3 discrimination and year-to-year variations in C3and C4 productivity are the main drivers of their IAV. But the year-to-year variability in the isotopic disequilibrium flux is much lower (1σ=±1.5 PgC ‰ yr-1) than required (±12.5 PgC ‰ yr-1) to match atmospheric observations, under the common assumption of low variability in net ocean CO2 fluxes. This contrasts with earlier published results. It is currently unclear how to increase IAV in these drivers suggesting that SiBCASA still misses processes that enhance variability in plant discrimination and relative C3/C4productivity. Alternatively, 13C budget terms other than terrestrial disequilibrium fluxes, including possibly the atmospheric growth rate, must have significantly different IAV in order to close the atmospheric 13C budget on a year-to-year basis.

Japan contribution to studies of low-latitude and equatorial ionosphere over Southeast Asia

NASA Astrophysics Data System (ADS)

Yamamoto, M.; Ishii, M.; Otsuka, Y.; Shiokawa, K.; Saito, A.; Tsuda, T.; Fukao, S.

2008-12-01

A dense observation network to study ionosphere is deployed over Southeast Asian countries of Indonesia, Thailand, and Vietnam. The Equatorial Atmosphere Radar (EAR) at Kototabang, Indonesia is the center facility, and supporting instruments, i.e., an ionosonde, a VHF ionosphere radar, an optical imager, a GPS scintillation receiver, a magnetometer, a meteor radar, etc. are collocated. NICT operates the ionosonde network SEALION (South East Asian Low-latitude IOnosonde Network) that meridionally extends from the EAR site to Chumphong and Chiang Mai in Thailand, and two more sites (Baq Liu and Phy Thuy) in Vietnam. Additional facilities are an MF radar at Pameungpeuk, Indonesia, and an optical imager at Darwin, Australia. We have been observing plasma bubbles since 2001, that, for example, contributed clarification of time- spatial structures of the phenomena, their relationship to the pre-reversal enhancement, control of bubble occurrence by the meridional winds, etc. We are starting studies of their seeding by means of atmospheric waves that propages from the lower atmosphere, too. In 2008, Nagoya University will soon install three Fabry-Perot interferometers at the EAR site, Chiang Mai, and Darwin. We also have a plan to install digital beacon receivers in some of these sites. Next research program that follows CPEA (Coupling Processes in the Equatorial Atmosphere, 2001-2007) is under planning now. Our main facilities cover ± 10° of geomagnetic latitude, where the magnetic declination is relatively small, and the geomagnetic equator is in the geographic northern hemisphere. We will review our achievements, and show on-going efforts and future plans. Collaboration with the C/NOFS satellite, and comparisons to results from the American sector should be beneficial for global-scale understanding of the equatorial ionosphere/atmosphere.

Atmospheric transformation of solar radiation reflected from the ocean

NASA Technical Reports Server (NTRS)

Malkevich, M. S.; Istomina, L. G.; Hovis, W. A., Jr.

1977-01-01

Airborne measurements of the brightness spectrum of the Atlantic Ocean in the wavelength region from 0.4 to 0.7 micron are analyzed. These measurements were made over a tropical region of the Atlantic from an aircraft at heights of 0.3 and 10.5 km during the TROPEX-72 experiment. The results are used to estimate the contribution of the atmosphere to the overall brightness of the ocean-atmosphere system. It is concluded that: (1) the atmosphere decreases the absolute brightness of the ocean by a factor of 5 to 10 and also strongly affects the spectral behavior of solar radiation reflected from the ocean surface; (2) the atmospheric contribution to overall brightness may vary considerably under real conditions; (3) finely dispersed particles and Rayleigh scattering affect the spectral distribution of solar radiation; and (4) the spectral composition of ocean-atmosphere brightness may be completely governed by the atmosphere.

Worldwide dispersion and deposition of radionuclides produced in atmospheric tests.

PubMed

Bennett, Burton G

2002-05-01

Radionuclides produced in atmospheric nuclear tests were widely dispersed in the global environment. From the many measurements of the concentrations in air and the deposition amounts, much was learned of atmospheric circulation and environmental processes. Based on these results and the reported fission and total yields of individual tests, it has been possible to devise an empirical model of the movement and residence times of particles in the various atmospheric regions. This model, applied to all atmospheric weapons tests, allows extensive calculations of air concentrations and deposition amounts for the entire range of radionuclides produced throughout the testing period. Especially for the shorter-lived fission radionuclides, for which measurement results at the time of the tests are less extensive, a more complete picture of levels and isotope ratios can be obtained, forming a basis for improved dose estimations. The contributions to worldwide fallout can be inferred from individual tests, from tests at specific sites, or by specific countries. Progress was also made in understanding the global hydrological and carbon cycles from the tritium and 14C measurements. A review of the global measurements and modeling results is presented in this paper. In the future, if injections of materials into the atmosphere occur, their anticipated motions and fates can be predicted from the knowledge gained from the fallout experience.

Marine bacterial degradation of brominated methanes

USGS Publications Warehouse

Goodwin, K.D.; Lidstrom, M.E.; Oremland, R.S.

1997-01-01

Brominated methanes are ozone-depleting compounds whose natural sources include marine algae such as kelp. Brominated methane degradation by bacteria was investigated to address whether bacterial processes might effect net emission of these compounds to the atmosphere. Bacteria in seawater collected from California kelp beds degraded CH2Br2 but not CHBr3. Specific inhibitors showed that methanotrophs and nitrifiers did not significantly contribute to CH2Br2 removal. A seawater enrichment culture oxidized 14CH2Br2 to 14CO2 as well as 14CH3Br to 14CO2. The rates of CH2Br2 degradation in laboratory experiments suggest that bacterial degradation of CH2Br2 in a kelp bed accounts for <1% of the CH2Br2 produced by the kelp. However, the half-life of CH2Br2 due to bacterial removal appears faster than hydrolysis and within an order of magnitude of volatilization to the atmosphere.Brominated methanes are ozone-depleting compounds whose natural sources include marine algae such as kelp. Brominated methane degradation by bacteria was investigated to address whether bacterial processes might effect net emission of these compounds to the atmosphere. Bacteria in seawater collected from California kelp beds degraded CH2Br2 but not CHBr3. Specific inhibitors showed that methanotrophs and nitrifiers did not significantly contribute to CH2Br2 removal. A seawater enrichment culture oxidized 14CH2Br2 to 14CO2 as well as 14CH3Br to 14CO2. The rates of CH2Br2 degradation in laboratory experiments suggest that bacterial degradation of CH2Br2 in a kelp bed accounts for <1% of the CH2Br2 produced by the kelp. However, the half-life of CH2Br2 due to bacterial removal appears faster than hydrolysis and within an order of magnitude of volatilization to the atmosphere.

Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS)

NASA Technical Reports Server (NTRS)

Rhothermel, Jeffry; Jones, W. D.; Dunkin, J. A.; Mccaul, E. W., Jr.

1993-01-01

This effort involves development of a calibrated, pulsed coherent CO2 Doppler lidar, followed by a carefully-planned and -executed program of multi-dimensional wind velocity and aerosol backscatter measurements from the NASA DC-8 research aircraft. The lidar, designated as the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS), will be applicable to two research areas. First, MACAWS will enable specialized measurements of atmospheric dynamical processes in the planetary boundary layer and free troposphere in geographic locations and over scales of motion not routinely or easily accessible to conventional sensors. The proposed observations will contribute fundamentally to a greater understanding of the role of the mesoscale, helping to improve predictive capabilities for mesoscale phenomena and to provide insights into improving model parameterizations of sub-grid scale processes within large-scale circulation models. As such, it has the potential to contribute uniquely to major, multi-institutional field programs planned for the mid 1990's. Second, MACAWS measurements can be used to reduce the degree of uncertainty in performance assessments and algorithm development for NASA's prospective Laser Atmospheric Wind Sounder (LAWS), which has no space-based instrument heritage. Ground-based lidar measurements alone are insufficient to address all of the key issues. To minimize costs, MACAWS is being developed cooperatively by the lidar remote sensing groups of the Jet Propulsion Laboratory, NOAA Wave Propagation Laboratory, and MSFC using existing lidar hardware and manpower resources. Several lidar components have already been exercised in previous airborne lidar programs (for example, MSFC Airborne Doppler Lidar System (ADLS) used in 1981,4 Severe Storms Wind Measurement Program; JPL Airborne Backscatter Lidar Experiment (ABLE) used in 1989,90 Global Backscatter Experiment Survey Missions). MSFC has been given responsibility for directing the overall program of instrument development and scientific measurement. The focus of current research and plans for next year are presented.

Investigation of the 3D temperature distribution patterns above the Antarctic Peninsula using remote sensing data - A contribution for polar climate monitoring

NASA Astrophysics Data System (ADS)

Wachter, Paul; Höppner, Kathrin; Jacobeit, Jucundus; Diedrich, Erhard

2015-04-01

West Antarctica and the Antarctic Peninsula are in the focus of current studies on a changing environment and climate of the polar regions. A recently founded Junior Researchers Group at the German Aerospace Center (DLR) is studying changing processes in cryosphere and atmosphere above the Antarctic Peninsula. It is the aim of the group to make use of long-term remote sensing data sets of the land and ice surfaces and the atmosphere in order to characterize environmental changes in this highly sensitive region. One of the PhD projects focuses on the investigation of the 3D temperature distribution patterns above the Antarctic Peninsula. Temperature data sets ranging from MODIS land surface temperatures up to middle atmosphere data of AURA/MLS will be evaluated over the last approx. 12 years. This 3-dimensional view allows comprehensive investigations of the thermal structure and spatio-temporal characteristics of the southern polar atmosphere. Tropospheric data sets will be analyzed by multivariate statistical methods and will allow the identification of dominant atmospheric circulation patterns as well as their temporal variability. An overview of the data sets and first results will be presented.

Flux of the biogenic volatiles isoprene and dimethyl sulfide from an oligotrophic lake.

PubMed

Steinke, Michael; Hodapp, Bettina; Subhan, Rameez; Bell, Thomas G; Martin-Creuzburg, Dominik

2018-01-12

Biogenic volatile organic compounds (BVOCs) affect atmospheric chemistry, climate and regional air quality in terrestrial and marine atmospheres. Although isoprene is a major BVOC produced in vascular plants, and marine phototrophs release dimethyl sulfide (DMS), lakes have been widely ignored for their production. Here we demonstrate that oligotrophic Lake Constance, a model for north temperate deep lakes, emits both volatiles to the atmosphere. Depth profiles indicated that highest concentrations of isoprene and DMS were associated with the chlorophyll maximum, suggesting that their production is closely linked to phototrophic processes. Significant correlations of the concentration patterns with taxon-specific fluorescence data, and measurements from algal cultures confirmed the phototrophic production of isoprene and DMS. Diurnal fluctuations in lake isoprene suggested an unrecognised physiological role in environmental acclimation similar to the antioxidant function of isoprene that has been suggested for marine biota. Flux estimations demonstrated that lakes are a currently undocumented source of DMS and isoprene to the atmosphere. Lakes may be of increasing importance for their contribution of isoprene and DMS to the atmosphere in the arctic zone where lake area coverage is high but terrestrial sources of BVOCs are small.

Some current themes in physical hydrology of the land-atmosphere interface

USGS Publications Warehouse

Milly, P.C.D.

1991-01-01

Certain themes arise repeatedly in current literature dealing with the physical hydrology of the interface between the atmosphere and the continents. Papers contributed to the 1991 International Association of Hydrological Sciences Symposium on Hydrological Interactions between Atmosphere, Soil and Vegetation echo these themes, which are discussed in this paper. The land-atmosphere interface is the region where atmosphere, soil, and vegetation have mutual physical contact, and a description of exchanges of matter or energy among these domains must often consider the physical properties and states of the entire system. A difficult family of problems is associated with the reconciliation of the wide range of spatial scales that arise in the course of observational, theoretical, and modeling activities. These scales are determined by some of the physical elements of the interface, by patterns of natural variability of the physical composition of the interface, by the dynamics of the processes at the interface, and by methods of measurement and computation. Global environmental problems are seen by many hydrologists as a major driving force for development of the science. The challenge for hydrologists will be to respond to this force as scientists rather than problem-solvers.

Simulation chamber studies of the atmospheric degradation of xylene oxidation products

NASA Astrophysics Data System (ADS)

Clifford, G.; Rea, G.; Thuener, L.; Wenger, J.

2003-04-01

Aromatic compounds are emitted to the atmosphere from their use in automobile fuels and solvents. In addition to being important primary pollutants, many aromatics, including the xylenes, possess high photochemical reactivity and make a major contribution to the formation of oxidants, such as ozone and nitrates, in the troposphere. The atmospheric oxidation of aromatics produces a wide variety of products and the atmospheric reactivity of many of these species is unknown. The aim of this work was to study the atmospheric degradation processes for dimethylphenols, tolualdehydes and dicarbonyl compounds which are produced from the hydroxyl radical initiated oxidation of the xylenes. Experiments on the hydroxyl (OH) and nitrate radical initiated oxidation of dimethylphenols and tolualdehydes have been performed in a large atmospheric simulation chamber in our laboratory. The chamber is made of FEP foil and has a volume of about 4750 litres. It is equipped with gas chromatography, GC-MS, and in situ FTIR spectroscopy for chemical analysis and a scanning mobility particle sizer for aerosol measurements. Rate coefficients have been determined for the reactions of hydroxyl and nitrate radicals with dimethylphenols and tolualdehydes. Gas-phase products and the yield of secondary organic aerosol have also been determined for the OH-initiated oxidation of these compounds. Mechanisms for the formation of the products are proposed. The photolysis of the unsaturated dicarbonyls, butenedial and 4-oxo-pent-2-enal, has been studied using real sunlight at the European Photoreactor (EUPHORE) in Valencia, Spain. Photolysis rates were measured and indicate that photolysis by sunlight is the major atmospheric degradation process for these compounds. Product studies show the formation of a ketene intermediate that decays to form five membered ring compounds such as furanones and maleic anhydride. Mechanisms for the formation of the products are proposed. Finally, the data obtained in this work is used to access the atmospheric impact of xylene oxidation products and to provide valuable information on their pollution forming potential.

Atmospherical simulations of the OMEGA/MEX observations

NASA Astrophysics Data System (ADS)

Melchiorri, R.; Drossart, P.; Combes, M.; Encrenaz, T.; Fouchet, T.; Forget, F.; Bibring, J. P.; Ignatiev, N.; Moroz, V.; OMEGA Team

The modelization of the atmospheric contribution in the martian spectrum is an important step for the OMEGA data analysis.A full line by line radiative transfer calculation is made for the gas absorption; the dust opacity component, in a first approximation, is calculated as an optically thin additive component.Due to the large number of parameters needed in the calculations, the building of a huge data base to be interpolated is not envisageable, for each observed OMEGA spectrum with calculation for all the involved parameters (atmospheric pressure, water abundance, CO abundance, dust opacity and geometric angles of observation). The simulation of the observations allows us to fix all the orbital parameters and leave the unknown parameters as the only variables.Starting from the predictions of the current meteorological models of Mars we build a smaller data base corresponding on each observation. We present here a first order simulation, which consists in retrieving atmospheric contribution from the solar reflected component as a multiplicative (for gas absorption) and an additive component (for suspended dust contribution); although a fully consistent approach will require to include surface and atmosphere contributions together in synthetic calculations, this approach is sufficient for retrieving mineralogic information cleaned from atmospheric absorption at first order.First comparison to OMEGA spectra will be presented, with first order retrieval of CO2 pressure, CO and H2O abundance, and dust opacity.

Collaborative Research: Process-Resolving Decomposition of the Global Temperature Response to Modes of Low Frequency Variability in a Changing Climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Yi

2014-11-24

DOE-GTRC-05596 11/24/2104 Collaborative Research: Process-Resolving Decomposition of the Global Temperature Response to Modes of Low Frequency Variability in a Changing Climate PI: Dr. Yi Deng (PI) School of Earth and Atmospheric Sciences Georgia Institute of Technology 404-385-1821, yi.deng@eas.gatech.edu El Niño-Southern Oscillation (ENSO) and Annular Modes (AMs) represent respectively the most important modes of low frequency variability in the tropical and extratropical circulations. The projection of future changes in the ENSO and AM variability, however, remains highly uncertain with the state-of-the-science climate models. This project conducted a process-resolving, quantitative evaluations of the ENSO and AM variability in the modern reanalysis observationsmore » and in climate model simulations. The goal is to identify and understand the sources of uncertainty and biases in models’ representation of ENSO and AM variability. Using a feedback analysis method originally formulated by one of the collaborative PIs, we partitioned the 3D atmospheric temperature anomalies and surface temperature anomalies associated with ENSO and AM variability into components linked to 1) radiation-related thermodynamic processes such as cloud and water vapor feedbacks, 2) local dynamical processes including convection and turbulent/diffusive energy transfer and 3) non-local dynamical processes such as the horizontal energy transport in the oceans and atmosphere. In the past 4 years, the research conducted at Georgia Tech under the support of this project has led to 15 peer-reviewed publications and 9 conference/workshop presentations. Two graduate students and one postdoctoral fellow also received research training through participating the project activities. This final technical report summarizes key scientific discoveries we made and provides also a list of all publications and conference presentations resulted from research activities at Georgia Tech. The main findings include: 1) the distinctly different roles played by atmospheric dynamical processes in establishing surface temperature response to ENSO at tropics and extratropics (i.e., atmospheric dynamics disperses energy out of tropics during ENSO warm events and modulate surface temperature at mid-, high-latitudes through controlling downward longwave radiation); 2) the representations of ENSO-related temperature response in climate models fail to converge at the process-level particularly over extratropics (i.e., models produce the right temperature responses to ENSO but with wrong reasons); 3) water vapor feedback contributes substantially to the temperature anomalies found over U.S. during different phases of the Northern Annular Mode (NAM), which adds new insight to the traditional picture that cold/warm advective processes are the main drivers of local temperature responses to the NAM; 4) the overall land surface temperature biases in the latest NCAR model (CESM1) are caused by biases in surface albedo while the surface temperature biases over ocean are related to multiple factors including biases in model albedo, cloud and oceanic dynamics, and the temperature biases over different ocean basins are also induced by different process biases. These results provide a detailed guidance for process-level model turning and improvement, and thus contribute directly to the overall goal of reducing model uncertainty in projecting future changes in the Earth’s climate system, especially in the ENSO and AM variability.« less

Triton: The Connection between Rosetta, New Horizons and a future Ice Giants Mission

NASA Astrophysics Data System (ADS)

Mandt, K.; Luspay-Kuti, A.; Mousis, O.

2017-12-01

Several planetary missions have made observations intended to evaluate the origin and evolution of volatiles in solar system atmospheres. This is an important topic that connects how planets, moons and small bodies formed to the question of past or present habitability. Comet isotope observations have been ongoing and have played a crucial role in this research. Measurements of the D/H in cometary water and 14N/15N in NH3, in particular, have been critical for evaluating the origin of water and nitrogen in the terrestrial planet atmospheres and for that of Saturn's moon Titan. We have conducted comparative studies modeling the escape, photochemistry and evolution of the atmospheres of Titan and Pluto to try to understand whether the nitrogen in these atmospheres originated as N2 or NH3 in the protosolar nebula. The origin of Titan's nitrogen has been well constrained, but uncertainties about isotope processes in Pluto's atmosphere leave the origin of Pluto's nitrogen difficult to resolve. Because of their similarities, Triton is subject to the same uncertainties and is of particular interest for understanding the origin of Triton's and Pluto's volatiles as well as of Kuiper Belt Objects in general. We will discuss how Rosetta, New Horizons and a future Ice Giants mission will each contribute to understanding the origin of nitrogen in these atmospheres and to the origin of volatiles in atmospheres throughout outer solar system.

Global structure and composition of the martian atmosphere with SPICAM on Mars express

NASA Astrophysics Data System (ADS)

Bertaux, Jean-Loup; Korablev, O.; Fonteyn, D.; Guibert, S.; Chassefière, E.; Lefèvre, F.; Dimarellis, E.; Dubois, J. P.; Hauchecorne, A.; Cabane, M.; Rannou, P.; Levasseur-Regourd, A. C.; Cernogora, G.; Quémerais, E.; Hermans, C.; Kockarts, G.; Lippens, C.; de Maziere, M.; Moreau, D.; Muller, C.; Neefs, E.; Simon, P. C.; Forget, F.; Hourdin, F.; Talagrand, O.; Moroz, V. I.; Rodin, A.; Sandel, B.; Stern, A.

SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) Light, a light-weight (4.7 kg) UV-IR instrument to be flown on Mars Express orbiter, is dedicated to the study of the atmosphere and ionosphere of Mars. A UV spectrometer (118-320 nm, resolution 0.8 nm) is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation (3.8 kg). It addresses key issues about ozone, its coupling with H2O, aerosols, atmospheric vertical temperature structure and ionospheric studies. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. An IR spectrometer (1.0-1.7 μm, resolution 0.5-1.2 nm) is dedicated primarily to nadir measurements of H2O abundances simultaneously with ozone measured in the UV, and to vertical profiling during solar occultation of H2O, CO2, and aerosols. The SPICAM Light near-IR sensor employs a pioneering technology acousto-optical tunable filter (AOTF), leading to a compact and light design. Overall, SPICAM Light is an ideal candidate for future orbiter studies of Mars, after Mars Express, in order to study the interannual variability of martian atmospheric processes. The potential contribution to a Mars International Reference Atmosphere is clear.

Atmospheric ions, boreal forests and impacts on climate

NASA Astrophysics Data System (ADS)

Manninen, H. E.; Nieminen, T.; Franchin, A.; Järvinen, E.; Kontkanen, J.; Hirsikko, A.; Hõrrak, U.; Mirme, A.; Tammet, H.; Kerminen, V.-M.; Petäjä, T.; Kulmala, M.

2012-04-01

Aerosol particles play an important role in the Earth's atmosphere and in the climate system: They scatter and absorb solar radiation, facilitate chemical processes, and serve as seeds for cloud formation. The aerosol particles have direct cooling and warming effects on climate (IPCC, 2007). Secondary new particle formation (NPF) is a globally important source of aerosol particles (Kulmala and Kerminen, 2008). Currently, the mechanisms of particle formation and the vapors participating in this process are, however, not truly understood. Several formation and growth mechanisms have been proposed for the very first steps of the process: homogeneous, heterogeneous, ion-induced and kinetic nucleation and activation type cluster growth. Small ions are part of the atmospheric aerosol spectrum, and in atmospheric sciences study of ion-aerosol interactions is essential. Small ions are small molecular clusters carrying a net electric charge. They are produced by ionisation of molecules in the air. Typically the small ion concentrations vary in the range of 100-2000 cm-3 in both polarities (Hirsikko et al., 2011). Ion-induced NPF is limited by the ion production rate, which typically is around 10 ion pairs cm-3s-1 in the boundary layer over the ground. The ion production rate has strong spatial and temporal dependence. The ionisation mechanisms change with altitude: radon and gamma radiation from the ground and galactic cosmic rays dominate close to the Earth's surface, while higher in the free troposphere cosmic rays become the main driving factor. In order to fully explain atmospheric NPF and subsequent growth, we need to measure directly the very initial steps of the formation processes. Air ion spectrometers measure the mobility distributions of charged aerosol particles in the mobility diameter range of 0.8-42 nm (Mirme et al., 2007; Tammet et al., 2011). Neutral cluster and air ion spectrometers measure additionally the mobility distribution of neutral particles larger than 2 nm in diameter by charging the aerosol sample with unipolar corona chargers (Manninen et al., 2009). According to earlier studies, the atmospheric nucleation and cluster activation take place at the mobility diameter range of 1.5-2 nm. Therefore, the ion spectrometers allow direct measurements at exactly the size where atmospheric nucleation takes place. The results indicate that the ion-induced nucleation contributes ~1-30% to the NPF events in most atmospheric conditions (Manninen et al., 2010). In other words, neutral particle formation seems to dominate over ion-mediated mechanisms, at least in the boreal forest conditions. Acknowledgements. This research was supported by the Academy of Finland Center of Excellence program (project number 1118615). Hirsikko, A. et al.: Atmospheric ions and nucleation: a review of observations, Atmos. Chem. Phys., 11, 767-798, 2011. IPCC, Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK and New York, NY, USA, 996 pp, 2007. Kulmala, M., and Kerminen, V.-M.: On the growth of atmospheric nanoparticles, Atmos. Res., 90, 132-150, 2008. Manninen, H.E. et al.: Long-term field measurements of charged and neutral clusters using Neutral cluster and Air Ion Spectrometer (NAIS). Boreal Env. Res. 14, 591-605, 2009. Manninen, H.E. et al., EUCAARI ion spectrometer measurements at 12 European sites - analysis of new particle formation events, Atmos. Chem. Phys., 10, 7907-7927, 2010. Mirme, A. et al.: A Wide-range multi-channel Air Ion Spectrometer, Boreal Environ. Res., 12, 247-264, 2007. Tammet, H.: Symmetric inclined grid mobility analyzer for the measurement of charged clusters and fine nanoparticles in atmospheric air. Aerosol Science and Technology, 45, 468 - 479, 2011.

The Outsized Influence of a Primordial Lunar Atmosphere

NASA Astrophysics Data System (ADS)

Saxena, Prabal; Elkins-Tanton, Linda T.; Petro, Noah; Mandell, Avi

2016-10-01

Immediately following formation of the moon, its surface was subject to radiative influences from the Lunar Magma Ocean, an early Earth that radiated like a mid type M Dwarf Star, and the early Sun. These contributions have been hypothesized to have produced a vapor pressure atmosphere on the Moon. We model the early atmosphere of the Moon using an atmospheric model originally developed for Io. We also use a magma ocean crystallization model that finds that heating from the early Earth delays crystallization of the Lunar Magma Ocean and contributes to a moderate pressure and collapsing metal-dominated atmosphere on the earthside of the Moon until lid formation. The atmosphere is characterized by maximum pressures ~1 bar and strong horizontal supersonic winds that decreased as the Moon's orbital separation increased. Crustal and other compositional asymmetries may have been influenced by this atmosphere. The atmosphere transported significant amounts of mass horizontally and may have been a source for present day depletions and heterogeneities of moderately volatile elements on the lunar surface.

Fate of Ammonia Emissions at the Local to Regional Scale as Simulated by the Community Multiscale Air Quality Model

EPA Science Inventory

Atmospheric deposition of nitrogen contributes to eutrophication of estuarine waters and acidification of lakes and streams. Ammonia also contributes to fine particle formation in the atmosphere and associated health effects. Model projections suggest that NH₃ depositi...

A Global Perspective of Atmospheric CO2 Concentrations

NASA Technical Reports Server (NTRS)

Putman, William M.; Ott, Lesley; Darmenov, Anton; daSilva, Arlindo

2016-01-01

Carbon dioxide (CO2) is the most important greenhouse gas affected by human activity. About half of the CO2 emitted from fossil fuel combustion remains in the atmosphere, contributing to rising temperatures, while the other half is absorbed by natural land and ocean carbon reservoirs. Despite the importance of CO2, many questions remain regarding the processes that control these fluxes and how they may change in response to a changing climate. The Orbiting Carbon Observatory-2 (OCO-2), launched on July 2, 2014, is NASA's first satellite mission designed to provide the global view of atmospheric CO2 needed to better understand both human emissions and natural fluxes. This visualization shows how column CO2 mixing ratio, the quantity observed by OCO-2, varies throughout the year. By observing spatial and temporal gradients in CO2 like those shown, OCO-2 data will improve our understanding of carbon flux estimates. But, CO2 observations can't do that alone. This visualization also shows that column CO2 mixing ratios are strongly affected by large-scale weather systems. In order to fully understand carbon flux processes, OCO-2 observations and atmospheric models will work closely together to determine when and where observed CO2 came from. Together, the combination of high-resolution data and models will guide climate models towards more reliable predictions of future conditions.

Multi-factor evaluation indicator method for the risk assessment of atmospheric and oceanic hazard group due to the attack of tropical cyclones

NASA Astrophysics Data System (ADS)

Qi, Peng; Du, Mei

2018-06-01

China's southeast coastal areas frequently suffer from storm surge due to the attack of tropical cyclones (TCs) every year. Hazards induced by TCs are complex, such as strong wind, huge waves, storm surge, heavy rain, floods, and so on. The atmospheric and oceanic hazards cause serious disasters and substantial economic losses. This paper, from the perspective of hazard group, sets up a multi-factor evaluation method for the risk assessment of TC hazards using historical extreme data of concerned atmospheric and oceanic elements. Based on the natural hazard dynamic process, the multi-factor indicator system is composed of nine natural hazard factors representing intensity and frequency, respectively. Contributing to the indicator system, in order of importance, are maximum wind speed by TCs, attack frequency of TCs, maximum surge height, maximum wave height, frequency of gusts ≥ Scale 8, rainstorm intensity, maximum tidal range, rainstorm frequency, then sea-level rising rate. The first four factors are the most important, whose weights exceed 10% in the indicator system. With normalization processing, all the single-hazard factors are superposed by multiplying their weights to generate a superposed TC hazard. The multi-factor evaluation indicator method was applied to the risk assessment of typhoon-induced atmospheric and oceanic hazard group in typhoon-prone southeast coastal cities of China.

Constraining land carbon cycle process understanding with observations of atmospheric CO2 variability

NASA Astrophysics Data System (ADS)

Collatz, G. J.; Kawa, S. R.; Liu, Y.; Zeng, F.; Ivanoff, A.

2013-12-01

We evaluate our understanding of the land biospheric carbon cycle by benchmarking a model and its variants to atmospheric CO2 observations and to an atmospheric CO2 inversion. Though the seasonal cycle in CO2 observations is well simulated by the model (RMSE/standard deviation of observations <0.5 at most sites north of 15N and <1 for Southern Hemisphere sites) different model setups suggest that the CO2 seasonal cycle provides some constraint on gross photosynthesis, respiration, and fire fluxes revealed in the amplitude and phase at northern latitude sites. CarbonTracker inversions (CT) and model show similar phasing of the seasonal fluxes but agreement in the amplitude varies by region. We also evaluate interannual variability (IAV) in the measured atmospheric CO2 which, in contrast to the seasonal cycle, is not well represented by the model. We estimate the contributions of biospheric and fire fluxes, and atmospheric transport variability to explaining observed variability in measured CO2. Comparisons with CT show that modeled IAV has some correspondence to the inversion results >40N though fluxes match poorly at regional to continental scales. Regional and global fire emissions are strongly correlated with variability observed at northern flask sample sites and in the global atmospheric CO2 growth rate though in the latter case fire emissions anomalies are not large enough to account fully for the observed variability. We discuss remaining unexplained variability in CO2 observations in terms of the representation of fluxes by the model. This work also demonstrates the limitations of the current network of CO2 observations and the potential of new denser surface measurements and space based column measurements for constraining carbon cycle processes in models.

Scientific rationale for Uranus and Neptune in situ explorations

NASA Astrophysics Data System (ADS)

Mousis, O.; Atkinson, D. H.; Cavalié, T.; Fletcher, L. N.; Amato, M. J.; Aslam, S.; Ferri, F.; Renard, J.-B.; Spilker, T.; Venkatapathy, E.; Wurz, P.; Aplin, K.; Coustenis, A.; Deleuil, M.; Dobrijevic, M.; Fouchet, T.; Guillot, T.; Hartogh, P.; Hewagama, T.; Hofstadter, M. D.; Hue, V.; Hueso, R.; Lebreton, J.-P.; Lellouch, E.; Moses, J.; Orton, G. S.; Pearl, J. C.; Sánchez-Lavega, A.; Simon, A.; Venot, O.; Waite, J. H.; Achterberg, R. K.; Atreya, S.; Billebaud, F.; Blanc, M.; Borget, F.; Brugger, B.; Charnoz, S.; Chiavassa, T.; Cottini, V.; d'Hendecourt, L.; Danger, G.; Encrenaz, T.; Gorius, N. J. P.; Jorda, L.; Marty, B.; Moreno, R.; Morse, A.; Nixon, C.; Reh, K.; Ronnet, T.; Schmider, F.-X.; Sheridan, S.; Sotin, C.; Vernazza, P.; Villanueva, G. L.

2018-06-01

The ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Presumed to have a small rocky core, a deep interior comprising ∼70% heavy elements surrounded by a more dilute outer envelope of H2 and He, Uranus and Neptune are fundamentally different from the better-explored gas giants Jupiter and Saturn. Because of the lack of dedicated exploration missions, our knowledge of the composition and atmospheric processes of these distant worlds is primarily derived from remote sensing from Earth-based observatories and space telescopes. As a result, Uranus's and Neptune's physical and atmospheric properties remain poorly constrained and their roles in the evolution of the Solar System not well understood. Exploration of an ice giant system is therefore a high-priority science objective as these systems (including the magnetosphere, satellites, rings, atmosphere, and interior) challenge our understanding of planetary formation and evolution. Here we describe the main scientific goals to be addressed by a future in situ exploration of an ice giant. An atmospheric entry probe targeting the 10-bar level, about 5 scale heights beneath the tropopause, would yield insight into two broad themes: i) the formation history of the ice giants and, in a broader extent, that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. In addition, possible mission concepts and partnerships are presented, and a strawman ice-giant probe payload is described. An ice-giant atmospheric probe could represent a significant ESA contribution to a future NASA ice-giant flagship mission.

Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

NASA Astrophysics Data System (ADS)

Schmitt-Kopplin, P.; Liger-Belair, G.; Koch, B. P.; Flerus, R.; Kattner, G.; Harir, M.; Kanawati, B.; Lucio, M.; Tziotis, D.; Hertkorn, N.; Gebefügi, I.

2012-04-01

Atmospheric aerosols impose direct and indirect effects on the climate system, for example, by absorption of radiation in relation to cloud droplets size, on chemical and organic composition and cloud dynamics. The first step in the formation of Organic primary aerosols, i.e. the transfer of dissolved organic matter from the marine surface into the atmosphere, was studied. We present a molecular level description of this phenomenon using the high resolution analytical tools of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy (NMR). Our experiments confirm the chemoselective transfer of natural organic molecules, especially of aliphatic compounds from the surface water into the atmosphere via bubble bursting processes. Transfer from marine surface water to the atmosphere involves a chemical gradient governed by the physicochemical properties of the involved molecules when comparing elemental compositions and differentiating CHO, CHNO, CHOS and CHNOS bearing compounds. Typical chemical fingerprints of compounds enriched in the aerosol phase were CHO and CHOS molecular series, smaller molecules of higher aliphaticity and lower oxygen content, and typical surfactants. A non-targeted metabolomics analysis demonstrated that many of these molecules corresponded to homologous series of oxo-, hydroxy-, methoxy-, branched fatty acids and mono-, di- and tricarboxylic acids as well as monoterpenes and sugars. These surface active biomolecules were preferentially transferred from surface water into the atmosphere via bubble bursting processes to form a significant fraction of primary organic aerosols. This way of sea spray production leaves a selective biological signature of the surface water in the corresponding aerosol that may be transported into higher altitudes up to the lower atmosphere, thus contributing to the formation of secondary organic aerosol on a global scale or transported laterally with possible deposition in the context of global biogeocycling.

Toward Process-resolving Synthesis and Prediction of Arctic Climate Change Using the Regional Arctic System Model

NASA Astrophysics Data System (ADS)

Maslowski, W.

2017-12-01

The Regional Arctic System Model (RASM) has been developed to better understand the operation of Arctic System at process scale and to improve prediction of its change at a spectrum of time scales. RASM is a pan-Arctic, fully coupled ice-ocean-atmosphere-land model with marine biogeochemistry extension to the ocean and sea ice models. The main goal of our research is to advance a system-level understanding of critical processes and feedbacks in the Arctic and their links with the Earth System. The secondary, an equally important objective, is to identify model needs for new or additional observations to better understand such processes and to help constrain models. Finally, RASM has been used to produce sea ice forecasts for September 2016 and 2017, in contribution to the Sea Ice Outlook of the Sea Ice Prediction Network. Future RASM forecasts, are likely to include increased resolution for model components and ecosystem predictions. Such research is in direct support of the US environmental assessment and prediction needs, including those of the U.S. Navy, Department of Defense, and the recent IARPC Arctic Research Plan 2017-2021. In addition to an overview of RASM technical details, selected model results are presented from a hierarchy of climate models together with available observations in the region to better understand potential oceanic contributions to polar amplification. RASM simulations are analyzed to evaluate model skill in representing seasonal climatology as well as interannual and multi-decadal climate variability and predictions. Selected physical processes and resulting feedbacks are discussed to emphasize the need for fully coupled climate model simulations, high model resolution and sensitivity of simulated sea ice states to scale dependent model parameterizations controlling ice dynamics, thermodynamics and coupling with the atmosphere and ocean.

Non-invasive monitoring and modelling of the root active zones: progresses, caveats and outlook.

NASA Astrophysics Data System (ADS)

Cassiani, G.; Putti, M.; Boaga, J.; Busato, L.; Vanella, D.; Consoli, S.

2016-12-01

Roots play a fundamental role in soil-plant-atmosphere interactions as they not only control water and nutrient exchanges necessary for plant sustenance, but also largely contribute, through the plant system, to the mass and energy exchanges between soil and atmosphere. Therefore understanding root zone processes is of major importance not only for crop management but also for wider scale catchment and global issues. Geophysical methods can greatly contribute to imaging the root zone geometry and processes, provided that high-resolution, time-lapse measurements are set up, and provided that the survey design takes into due considerations the expected processes to be imaged. In this respect, modelling and monitoring go hand in hand not only a-posteriori to try and interpret the data, but also a-priori in the attempt to optimise monitoring strategies. In this work we present a few case studies concerning root monitoring using ERT with the support of ancillary data of hydrological and physiological nature. Different degrees of integration with modelling will be presented, with the aim of showing how a full Data Assimilation scheme can be built. In addition, the results will help address fundamental questions such as: (a) is root growth controlled by optimality principles under the constraints posed by soil hydraulic and mechanical properties, by water and nutrient availability and by plant competition? (b) is the optimality above also controlling the dynamic processing of root adaptation to changing constraints? (c) to what extent can these processes of soil-plant interaction be monitored in controlled conditions as well as in true-life environments? These questions, and the availability of ever advancing modelling and monitoring capabilities, are likely to develop into a growing and exciting field of research.

Methodology and significance of studies of atmospheric deposition in highway runoff

USGS Publications Warehouse

Colman, John A.; Rice, Karen C.; Willoughby, Timothy C.

2001-01-01

Atmospheric deposition and the processes that are involved in causing and altering atmospheric deposition in relation to highway surfaces and runoff were evaluated nationwide. Wet deposition is more easily monitored than dry deposition, and data on wet deposition are available for major elements and water properties (constituents affecting acid deposition) from the inter-agency National Atmospheric Deposition Program/ National Trends Network (NADP/NTN). Many trace constituents (metals and organic compounds) of interest in highway runoff loads, however, are not included in the NADP/NTN. Dry deposition, which constitutes a large part of total atmospheric deposition for many constituents in highway runoff loads, is difficult to monitor accurately. Dry-deposition rates are not widely available.Many of the highway-runoff investigations that have addressed atmospheric-deposition sources have had flawed investigative designs or problems with methodology. Some results may be incorrect because of reliance on time-aggregated data collected during a period of changing atmospheric emissions. None of the investigations used methods that could accurately quantify the part of highway runoff load that can be attributed to ambient atmospheric deposition. Lack of information about accurate ambient deposition rates and runoff loads was part of the problem. Samples collected to compute the rates and loads were collected without clean-sampling methods or sampler protocols, and without quality-assurance procedures that could validate the data. Massbudget calculations comparing deposition and runoff did not consider loss of deposited material during on-highway processing. Loss of deposited particles from highway travel lanes could be large, as has been determined in labeled particle studies, because of resuspension caused by turbulence from passing traffic. Although a cause of resuspension of large particles, traffic turbulence may increase the rate of deposition for small particles and gases by impaction, especially during precipitation periods.Ultimately, traffic and road maintenance may be determined to be the source of many constituents measured in highway runoff previously attributed to ambient atmospheric deposition. An investigative design using tracers of ambient deposition that are not present in highway traffic sources could determine conclusively what fraction of highway runoff load is contributed by ambient atmospheric deposition.

Land-atmosphere interaction and disaster-causing process of drought in northern China: observation and experiment (DroughtPEX_China)

NASA Astrophysics Data System (ADS)

Li, Yaohui

2017-04-01

Drought is one of the most common and frequent nature disasters in the world, particularly in China under the continental monsoonal climate with great variation. About thirty percent of economic loss caused by natural disasters is contributed by droughts in China, which is by far the most damaging weather disasters because of its long duration and extensive hazard areas. Droughts not only have a serious impact on the agriculture, water resources, ecology, natural environment, but also seriously affect the socio-economic such as human health, energy and transportation. Worsely, under the background of climate change, droughts in show increases in frequency, duration and scope in many places around the world, particularly northern China. Nowadays, droughts have aroused extensive concern of the scientists, governments and international community, and became one of the important scientific issues in geoscience research. However, most of researches on droughts in China so far were focused on the causes or regulars of one type of droughts (the atmosphere, agriculture or hydrological) from the perspective of the atmospheric circulation anomalies. Few of them considered a whole cycle of the drought-forming process from atmosphere-land interaction to agricultural/ecological one in terms of the land-atmosphere interaction; meanwhile, the feedback mechanism with the drought and land-atmosphere interaction is still unclear as well. All of them is because of lack of the relevant comprehensive observation experiment. "Land-atmosphere interaction and disaster-causing process of drought in northern China: observation and experiment" (DroughtPEX_China)is just launched in this requirement and background. DroughtPEX_China is supported by Special Scientific Research Fund of Public Welfare Industry (Meteorological) of China (Grant No.GYHY201506001)—"Drought Meteorology Scientific Research Project—the disaster-causing process and mechanism of drought in northern China". This project aims to establish a complete observation &experiment system for droughts particularly over the arid and semi-arid regions in northern China. Relying on the existing meteorological observation network and experimental bases, the DroughtPEX_China implemented interdisciplinary, comprehensive and systemic drought-scientific experiment including the routine observation, intensive and special observation, and the artificially field control test for the drought forming and reducing. Such large observation &experiment will promote a large step or theoretical breakthrough on the knowledge of the complex dynamic process for the formation and development of drought disasters, the mechanism of the water-energy cycle in the atmosphere-soil-vegetation on multi-scales, and the interrelationship in the atmosphere, agriculture and hydrological droughts. The ultimate purpose of DroughtPEX_China is to make great progress on the technology of accurate drought monitoring, risk assessment and early warning. This paper will introduce the Drought PEX_China with the scientific goal, experiment design and layout, preliminary results, information sharing, and its promoting role on international cooperation of drought scientific research. Key words: Disaster-causing process of drought; Observation & experiment; Northern China

Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and a Source of Titan's Aerosols?

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.; Ali, A.; Cooper, J. F.; Hartle, R. E.; Johnson, R. E.; Coates, A. J.; Young, D. T.

2009-01-01

Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with approx.2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from the surface to 1200 km altitudes. The energy sources are solar UV, solar X-rays, Saturn's magnetospheric ions and electrons, solar wind and shocked magnetosheath ions and electrons, galactic cosmic rays (CCR) and the ablation of incident meteoritic dust from Enceladus' E-ring and interplanetary medium. Here it is proposed that the heavy atmospheric ions detected in situ by Cassini for heights >950 km, are the likely seed particles for aerosols detected by the Huygens probe for altitudes <100km. These seed particles may be in the form of polycyclic aromatic hydrocarbons (PAH) containing both carbon and hydrogen atoms CnHx. There could also be hollow shells of carbon atoms, such as C60, called fullerenes which contain no hydrogen. The fullerenes may compose a significant fraction of the seed particles with PAHs contributing the rest. As shown by Cassini, the upper atmosphere is bombarded by magnetospheric plasma composed of protons, H(2+) and water group ions. The latter provide keV oxygen, hydroxyl and water ions to Titan's upper atmosphere and can become trapped within the fullerene molecules and ions. Pickup keV N(2+), N(+) and CH(4+) can also be implanted inside of fullerenes. Attachment of oxygen ions to PAH molecules is uncertain, but following thermalization O(+) can interact with abundant CH4 contributing to the CO and CO2 observed in Titan's atmosphere. If an exogenic keV O(+) ion is implanted into the haze particles, it could become free oxygen within those aerosols that eventually fall onto Titan's surface. The process of freeing oxygen within aerosols could be driven by cosmic ray interactions with aerosols at all heights. This process could drive pre-biotic chemistry within the descending aerosols. Cosmic ray interactions with grains at the surface, including water frost depositing on grains from cryovolcanism, would further add to abundance of trapped free oxygen. Pre-biotic chemistry could arise within surface microcosms of the composite organic-ice grains, in part driven by free oxygen in the presence of organics and any heat sources, thereby raising the astrobiological potential for microscopic equivalents of Darwin's "warm ponds" on Titan.

Nonlinear dynamics of mushy layers induced by external stochastic fluctuations.

PubMed

Alexandrov, Dmitri V; Bashkirtseva, Irina A; Ryashko, Lev B

2018-02-28

The time-dependent process of directional crystallization in the presence of a mushy layer is considered with allowance for arbitrary fluctuations in the atmospheric temperature and friction velocity. A nonlinear set of mushy layer equations and boundary conditions is solved analytically when the heat and mass fluxes at the boundary between the mushy layer and liquid phase are induced by turbulent motion in the liquid and, as a result, have the corresponding convective form. Namely, the 'solid phase-mushy layer' and 'mushy layer-liquid phase' phase transition boundaries as well as the solid fraction, temperature and concentration (salinity) distributions are found. If the atmospheric temperature and friction velocity are constant, the analytical solution takes a parametric form. In the more common case when they represent arbitrary functions of time, the analytical solution is given by means of the standard Cauchy problem. The deterministic and stochastic behaviour of the phase transition process is analysed on the basis of the obtained analytical solutions. In the case of stochastic fluctuations in the atmospheric temperature and friction velocity, the phase transition interfaces (mushy layer boundaries) move faster than in the deterministic case. A cumulative effect of these noise contributions is revealed as well. In other words, when the atmospheric temperature and friction velocity fluctuate simultaneously due to the influence of different external processes and phenomena, the phase transition boundaries move even faster. This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'. © 2018 The Author(s).

The Geostationary Fourier Transform Spectrometer

NASA Technical Reports Server (NTRS)

Key, Richard; Sander, Stanley; Eldering, Annmarie; Blavier, Jean-Francois; Bekker, Dmitriy; Manatt, Ken; Rider, David; Wu, Yen-Hung

2012-01-01

The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for a geostationary orbit (GEO) earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. GEO allows GeoFTS to continuously stare at a region of the earth for frequent sampling to capture the variability of biogenic fluxes and anthropogenic emissions from city to continental spatial scales and temporal scales from diurnal, synoptic, seasonal to interannual. The measurement strategy provides a process based understanding of the carbon cycle from contiguous maps of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) collected many times per day at high spatial resolution (2.7kmx2.7km at nadir). The CO2/CH4/CO/CF measurement suite in the near infrared spectral region provides the information needed to disentangle natural and anthropogenic contributions to atmospheric carbon concentrations and to minimize uncertainties in the flow of carbon between the atmosphere and surface. The half meter cube size GeoFTS instrument is based on a Michelson interferometer design that uses all high TRL components in a modular configuration to reduce complexity and cost. It is self-contained and as independent of the spacecraft as possible with simple spacecraft interfaces, making it ideal to be a "hosted" payload on a commercial communications satellite mission. The hosted payload approach for measuring the major carbon-containing gases in the atmosphere from the geostationary vantage point will affordably advance the scientific understating of carbon cycle processes and climate change.

Numerical calculation of cosmic ray ionization rate profiles in the middle atmosphere and lower ionosphere with relation to characteristic energy intervals

NASA Astrophysics Data System (ADS)

Velinov, Peter; Asenovski, Simeon; Mateev, Lachezar

2013-04-01

Numerical calculations of galactic cosmic ray (GCR) ionization rate profiles are presented for the middle atmosphere and lower ionosphere altitudes (35-90 km) for the full GCR composition (protons, alpha particles, and groups of heavier nuclei: light L, medium M, heavy H, very heavy VH). This investigation is based on a model developed by Velinov et al. (1974) and Velinov and Mateev (2008), which is further improved in the present paper. Analytical expressions for energy interval contributions are provided. An approximation of the ionization function on three energy intervals is used and for the first time the charge decrease interval for electron capturing (Dorman 2004) is investigated quantitatively. Development in this field of research is important for better understanding the impact of space weather on the atmosphere. GCRs influence the ionization and electric parameters in the atmosphere and also the chemical processes (ozone creation and depletion in the stratosphere) in it. The model results show good agreement with experimental data (Brasseur and Solomon 1986, Rosenberg and Lanzerotti 1979, Van Allen 1952).

Aerosol Size and Chemical Composition in the Canadian High Arctic

NASA Astrophysics Data System (ADS)

Chang, R. Y. W.; Hayes, P. L.; Leaitch, W. R.; Croft, B.; O'Neill, N. T.; Fogal, P.; Drummond, J. R.; Sloan, J. J.

2015-12-01

Arctic aerosol have a strong annual cycle, with winter months dominated by long range transport from lower latitudes resulting in high mass loadings. Conversely, local emissions are more prominent in the summer months because of the decreased influence of transported aerosol, allowing us to regularly observe both transported and local aerosol. This study will present observations of aerosol chemical composition and particle number size distribution collected at the Polar Environment Artic Research Laboratory and the Alert Global Atmospheric Watch Observatory at Eureka (80N, 86W) and Alert (82N, 62W), Nunavut, respectively. Summer time observations of the number size distribution reveal a persistent mode of particles centered between 30-50 nm, with occasional bursts of smaller particles. The non-refractory aerosol chemical composition, measured by the Canadian Network for the Detection of Atmospheric Change quadrupole aerosol mass spectrometer, is primarily organic, with contributions from both aged and fresher organic aerosol. Factor analysis will be conducted to better understand these sources. The site at Eureka is more susceptible to long range transport since it is at the top of a mountain ridge (610 m above sea level) and will be compared to the site at Alert on an elevated plain (200 m above sea level). This will allow us to determine the relative contributions from processes and sources at the sites at different elevations. Comparisons with aerosol optical depth and GEOS-Chem model output will also be presented to put these surface measurements into context with the overlying and regional atmosphere. Results from this study contribute to our knowledge of aerosol in the high Arctic.

Implications for carbon processing beneath the Greenland Ice Sheet from dissolved CO2 and CH4 concentrations of subglacial discharge

NASA Astrophysics Data System (ADS)

Pain, A.; Martin, J.; Martin, E. E.

2017-12-01

Subglacial carbon processes are of increasing interest as warming induces ice melting and increases fluxes of glacial meltwater into proglacial rivers and the coastal ocean. Meltwater may serve as an atmospheric source or sink of carbon dioxide (CO2) or methane (CH4), depending on the magnitudes of subglacial organic carbon (OC) remineralization, which produces CO2 and CH4, and mineral weathering reactions, which consume CO2 but not CH4. We report wide variability in dissolved CO2 and CH4 concentrations at the beginning of the melt season (May-June 2017) between three sites draining land-terminating glaciers of the Greenland Ice Sheet. Two sites, located along the Watson River in western Greenland, drain the Isunnguata and Russell Glaciers and contained 1060 and 400 ppm CO2, respectively. In-situ CO2 flux measurements indicated that the Isunnguata was a source of atmospheric CO2, while the Russell was a sink. Both sites had elevated CH4 concentrations, at 325 and 25 ppm CH4, respectively, suggesting active anaerobic OC remineralization beneath the ice sheet. Dissolved CO2 and CH4 reached atmospheric equilibrium within 2.6 and 8.6 km downstream of Isunnguata and Russell discharge sites, respectively. These changes reflect rapid gas exchange with the atmosphere and/or CO2 consumption via instream mineral weathering. The third site, draining the Kiagtut Sermiat in southern Greenland, had about half atmospheric CO2 concentrations (250 ppm), but approximately atmospheric CH4 concentrations (2.1 ppm). Downstream CO2 flux measurements indicated ingassing of CO2 over the entire 10-km length of the proglacial river. CO2 undersaturation may be due to more readily weathered lithologies underlying the Kiagtut Sermiat compared to Watson River sites, but low CH4 concentrations also suggest limited contributions of CO2 and CH4 from OC remineralization. These results suggest that carbon processing beneath the Greenland Ice Sheet may be more variable than previously recognized. Variations control whether discharge is a source or sink of atmospheric CO2 or CH4, but gas concentrations could be further modified by instream reactions. Increased meltwater fluxes should enhance the importance of greenhouse gas fluxes from subglacial discharge, and heighten the need to constrain variability in subglacial carbon processing.

Interconnection of reactive oxygen species chemistry across the interfaces of atmospheric, environmental, and biological processes.

PubMed

Anglada, Josep M; Martins-Costa, Marilia; Francisco, Joseph S; Ruiz-López, Manuel F

2015-03-17

Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in the environment, but they can also originate endogenously, initiated by electron reduction of molecular oxygen. These molecules have important biological signaling activities, but they cause oxidative stress when dysfunction within the antioxidant system occurs. Excess ROS in living organisms can lead to problems, such as protein oxidation-through either cleavage of the polypeptide chain or modification of amino acid side chains-and lipid oxidation.

The anthropogenic influence on Iron deposition over the oceans: a 3-D global modeling

NASA Astrophysics Data System (ADS)

Myriokefalitakis, Stelios; Mihalopoulos, Nikos; Baker, Alex; Kanakidou, Maria

2014-05-01

Iron (Fe) deposition over oceans is directly linked to the marine biological productivity and consequently to atmospheric CO2 concentrations. Experimental and modeling results support that both inorganic (sulphate, ammonium and nitrate) and organic (e.g. oxalate) ligands can increase the Fe mobilization. Mineral dust deposition is considered as the most important supply of bioavailable Fe in the oceans. Although, due to the low soil soluble iron fractions, atmospheric processes which are also related to anthropogenic emissions, can convert iron to more soluble forms in the atmosphere. Recent studies also support that anthropogenic emissions of Fe from combustion sources also significantly contribute to the dissolved Fe atmospheric pool. The evaluation of the impact of humans on atmospheric soluble or bioavailable Fe deposition remains challenging, since Fe mobilization due to changes in anthropogenic emissions is largely uncertain. In the present study, the global atmospheric Fe cycle is parameterized in the 3-D chemical transport global model TM4-ECPL and the model is used to calculate the Fe deposition over the oceans. The model considers explicitly organic, sulfur and nitrogen gas-phase chemistry, aqueous-phase organic chemistry, including oxalate and all major aerosol constituents. TM4-ECPL simulates the organic and inorganic ligand-promoted mineral Fe dissolution and also aqueous-phase photochemical reactions between different forms of Fe (III/II). Primary emissions of Fe associated with dust and soluble Fe from combustion processes as well as atmospheric processing of the emitted Fe is taken into account in the model Sensitivity simulations are performed to study the impact of anthropogenic emissions on Fe deposition. For this preindustrial, present and future emission scenarios are used in the model in order to examine the response of chemical composition of iron-containing aerosols to environmental changes. The release of soluble iron associated with mineral dust and with the emissions of combustion aerosols is investigated. Model results are compared with available observations to evaluate their robustness. This work is supported by the ESF-NSRF ARISTEIA grant PANOPLY (Pollution Alters Natural Aerosol Composition: implications for Ocean Productivity, cLimate and air qualitY).

On the Magnetic Protection of the Atmosphere of Proxima Centauri b

NASA Astrophysics Data System (ADS)

Garcia-Sage, K.; Glocer, A.; Drake, J. J.; Gronoff, G.; Cohen, O.

2017-07-01

The discovery of exoplanets orbiting red dwarfs, such as Proxima Centauri b, has led to questions of their habitability and capacity to retain liquid surface water. While Proxima b is in a “temperate orbit,” I.e., an Earth at that location would not freeze or boil its oceans, its proximity to a parent star with quite high magnetic activity is likely to influence its atmospheric evolution and habitability. Planetary magnetic fields can prevent direct stripping away of the planetary atmosphere by the stellar wind, but ion escape can still occur at the magnetic poles. This process, the polar wind, is well known to occur at Earth and may have contributed to the habitability of Earth’s early atmosphere. The polar wind is highly variable and sensitive to both ionizing radiation and geomagnetic activity. The higher ionizing radiation levels of M dwarfs at habitable zone distances are expected to increase the polar wind by orders of magnitude and, instead of helping create a habitable atmosphere, may strip away enough volatiles to render the planet inhospitable. Here, we compute the ionospheric outflow of an Earth-twin subject to the enhanced stellar EUV flux of Proxima b, and the effect on atmospheric escape timescales. We show that an Earth-like planet would not survive the escape of its atmosphere at that location, and therefore the pathway to habitability for Proxima b requires a very different atmospheric history than that of Earth.

On the Magnetic Protection of the Atmosphere of Proxima Centauri b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Sage, K.; Glocer, A.; Drake, J. J.

The discovery of exoplanets orbiting red dwarfs, such as Proxima Centauri b, has led to questions of their habitability and capacity to retain liquid surface water. While Proxima b is in a “temperate orbit,” i.e., an Earth at that location would not freeze or boil its oceans, its proximity to a parent star with quite high magnetic activity is likely to influence its atmospheric evolution and habitability. Planetary magnetic fields can prevent direct stripping away of the planetary atmosphere by the stellar wind, but ion escape can still occur at the magnetic poles. This process, the polar wind, is wellmore » known to occur at Earth and may have contributed to the habitability of Earth’s early atmosphere. The polar wind is highly variable and sensitive to both ionizing radiation and geomagnetic activity. The higher ionizing radiation levels of M dwarfs at habitable zone distances are expected to increase the polar wind by orders of magnitude and, instead of helping create a habitable atmosphere, may strip away enough volatiles to render the planet inhospitable. Here, we compute the ionospheric outflow of an Earth-twin subject to the enhanced stellar EUV flux of Proxima b, and the effect on atmospheric escape timescales. We show that an Earth-like planet would not survive the escape of its atmosphere at that location, and therefore the pathway to habitability for Proxima b requires a very different atmospheric history than that of Earth.« less

Local Cloudiness Development Forecast Based on Simulation of Solid Phase Formation Processes in the Atmosphere

NASA Astrophysics Data System (ADS)

Barodka, Siarhei; Kliutko, Yauhenia; Krasouski, Alexander; Papko, Iryna; Svetashev, Alexander; Turishev, Leonid

2013-04-01

Nowadays numerical simulation of thundercloud formation processes is of great interest as an actual problem from the practical point of view. Thunderclouds significantly affect airplane flights, and mesoscale weather forecast has much to contribute to facilitate the aviation forecast procedures. An accurate forecast can certainly help to avoid aviation accidents due to weather conditions. The present study focuses on modelling of the convective clouds development and thunder clouds detection on the basis of mesoscale atmospheric processes simulation, aiming at significantly improving the aeronautical forecast. In the analysis, the primary weather radar information has been used to be further adapted for mesoscale forecast systems. Two types of domains have been selected for modelling: an internal one (with radius of 8 km), and an external one (with radius of 300 km). The internal domain has been directly applied to study the local clouds development, and the external domain data has been treated as initial and final conditions for cloud cover formation. The domain height has been chosen according to the civil aviation forecast data (i.e. not exceeding 14 km). Simulations of weather conditions and local clouds development have been made within selected domains with the WRF modelling system. In several cases, thunderclouds are detected within the convective clouds. To specify the given category of clouds, we employ a simulation technique of solid phase formation processes in the atmosphere. Based on modelling results, we construct vertical profiles indicating the amount of solid phase in the atmosphere. Furthermore, we obtain profiles demonstrating the amount of ice particles and large particles (hailstones). While simulating the processes of solid phase formation, we investigate vertical and horizontal air flows. Consequently, we attempt to separate the total amount of solid phase into categories of small ice particles, large ice particles and hailstones. Also, we strive to reveal and differentiate the basic atmospheric parameters of sublimation and coagulation processes, aiming to predict ice particles precipitation. To analyze modelling results we apply the VAPOR three-dimensional visualization package. For the chosen domains, a diurnal synoptic situation has been simulated, including rain, sleet, ice pellets, and hail. As a result, we have obtained a large scope of data describing various atmospheric parameters: cloud cover, major wind components, basic levels of isobaric surfaces, and precipitation rate. Based on this data, we show both distinction in precipitation formation due to various heights and its differentiation of the ice particles. The relation between particle rise in the atmosphere and its size is analyzed: at 8-10 km altitude large ice particles, resulted from coagulation, dominate, while at 6-7 km altitude one can find snow and small ice particles formed by condensation growth. Also, mechanical trajectories of solid precipitation particles for various ice formation processes have been calculated.

Temporal and spatial characteristics of dust devils and their contribution to the aerosol budget in East Asia-An analysis using a new parameterization scheme for dust devils

NASA Astrophysics Data System (ADS)

Tang, Yaoguo; Han, Yongxiang; Liu, Zhaohuan

2018-06-01

Dust aerosols are the main aerosol components of the atmosphere that affect climate change, but the contribution of dust devils to the atmospheric dust aerosol budget is uncertain. In this study, a new parameterization scheme for dust devils was established and coupled with WRF-Chem, and the diurnal and monthly variations and the contribution of dust devils to the atmospheric dust aerosol budget in East Asia was simulated. The results show that 1) both the diurnal and monthly variations in dust devil emissions in East Asia had unimodal distributions, with peaks in the afternoon and the summer that were similar to the observations; 2) the simulated dust devils occurred frequently in deserts, including the Gobi. The distributed area and the intensity center of the dust devil moved from east to west during the day; 3) the ratio between the availability of convective buoyancy relative to the frictional dissipation was the main factor that limited the presence of dust devils. The position of the dust devil formation, the surface temperature, and the boundary layer height determined the dust devil intensity; 4) the contribution of dust devils to atmospheric dust aerosols determined in East Asia was 30.4 ± 13%, thereby suggesting that dust devils contribute significantly to the total amount of atmospheric dust aerosols. Although the new parameterization scheme for dust devils was rough, it was helpful for understanding the distribution of dust devils and their contribution to the dust aerosol budget.

Atlantic Induced Pan-tropical Climate Variability in the Upper-ocean and Atmosphere

NASA Astrophysics Data System (ADS)

Li, X.; Xie, S. P.; Gille, S. T.; Yoo, C.

2016-02-01

During the last three decades, tropical sea surface temperature (SST) exhibited dipole-like trends, with warming over the tropical Atlantic and Indo-Western Pacific but cooling over the Eastern Pacific. The Eastern Pacific cooling has recently been identified as a driver of the global warming hiatus. Previous studies revealed atmospheric bridges between the tropical Pacific, Atlantic, and Indian Ocean, which could potentially contribute to this zonally asymmetric SST pattern. However, the mechanisms and the interactions between these teleconnections remain unclear. To investigate these questions, we performed a `pacemaker' simulation by restoring the tropical Atlantic SST changes in a state-of-the-art climate model - the CESM1. Results show that the Atlantic plays a key role in initiating the tropical-wide teleconnections, and the Atlantic-induced anomalies contribute 55%-75% of the total tropical SST and circulation changes during the satellite era. A hierarchy of oceanic and atmospheric models are then used to investigate the physical mechanisms of these teleconnections: the Atlantic warming enhances atmospheric deep convection, drives easterly wind anomalies over the Indo-Western Pacific through the Kelvin wave, and westerly anomalies over the eastern Pacific as Rossby waves, in line with Gill's solution (Fig1a). These wind changes induce an Indo-Western Pacific warming via the wind-evaporation-SST effect, and this warming intensifies the La Niña-type response in the upper Pacific Ocean by enhancing the easterly trade winds and through the Bjerknes ocean-dynamical processes (Fig1b). The teleconnection finally develops into a tropical-wide SST dipole pattern with an enhanced trade wind and Walker circulation, similar as the observed changes during the satellite era. This mechanism reveals that the tropical ocean basins are more tightly connected than previously thought, and the Atlantic plays a key role in the tropical climate pattern formation and further the global warming hiatus. The tropical Atlantic warming is likely due to radiative forcing and Atlantic meridional overturning circulation (AMOC). Our study suggests that the AMOC may force the decadal variability of the tropical ocean and atmosphere, and thus contributes to the decadal predictability of the global climate.

Radon measurements aboard the Kuiper Airborne Observatory

NASA Technical Reports Server (NTRS)

Kritz, Mark A.; Rosner, Stefan W.

1995-01-01

We have carried out three (piggyback) radon-related projects aboard the KAO. The first, which was limited to upper tropospheric measurements while in level flight, revealed the systematic occurrence of unexpectedly high radon concentrations in this region of the atmosphere. The second project was an instrument development project, which led to the installation of an automatic radon measurement system aboard the NASA ER-2 High Altitude Research Aircraft. In the third, we installed a new system capable of collecting samples during the normal climb and descent of the KAO. The results obtained in these projects have resulted in significant contributions to our knowledge of atmospheric transport processes, and are currently playing a key role in the validation of global circulation and transport models.

The PreViBOSS project: study the short term predictability of the visibility change during the Fog life cycle, from surface and satellite observation

NASA Astrophysics Data System (ADS)

Elias, T.; Haeffelin, M.; Ramon, D.; Gomes, L.; Brunet, F.; Vrac, M.; Yiou, P.; Hello, G.; Petithomme, H.

2010-07-01

Fog prejudices major activities as transport and Earth observation, by critically reducing atmospheric visibility with no continuity in time and space. Fog is also an essential factor of air quality and climate as it modifies particle properties of the surface atmospheric layer. Complexity, diversity and the fine scale of processes make uncertain by current numerical weather prediction models, not only visibility diagnosis but also fog event prediction. Extensive measurements of atmospheric parameters are made on the SIRTA since 1997 to document physical processes over the atmospheric column, in the Paris suburb area, typical of an environment intermittently under oceanic influence and affected by urban and industrial pollution. The ParisFog field campaign hosted in SIRTA during 6-month in winter 2006-2007 resulted in the deployment of instrumentation specifically dedicated to study physical processes in the fog life cycle: thermodynamical, radiative, dynamical, microphysical processes. Analysis of the measurements provided a preliminary climatology of the episodes of reduced visibility, chronology of processes was delivered by examining time series of measured parameters and a closure study was performed on optical and microphysical properties of particles (aerosols to droplets) during the life cycle of a radiative fog, providing the relative contribution of several particle groups to extinction in clear-sky conditions, in haze and in fog. PreViBOSS is a 3-year project scheduled to start this year. The aim is to improve the short term prediction of changes in atmospheric visibility, at a local scale. It proposes an innovative approach: applying the Generalised Additive Model statistical method to the detailed and extended dataset acquired at SIRTA. This method offers the opportunity to explore non linear relationships between parameters, which are not yet integrated in current numerical models. Emphasis will be put on aerosols and their impact on the fog life cycle. Furthermore, the data set of ground-based measurements will be completed by spaceborne observation of visible and infra red radiance performed by the METEOSAT mission.

Gravity Waves in the Atmosphere of Mars as seen by the Radio Science Experiment MaRS on Mars Express

NASA Astrophysics Data System (ADS)

Tellmann, S.; Paetzold, M.; Häusler, B.; Bird, M. K.; Tyler, G. L.; Hinson, D. P.

2016-12-01

Gravity waves are atmospheric waves whose restoring force is the buoyancy. They are known to play an essential role in the redistribution of energy, momentum and atmospheric constituents in all stably stratified planetary atmospheres. Possible excitation mechanisms comprise convection in an adjacent atmospheric layer, other atmospheric instabilities like wind shear instabilities, or air flow over orographic obstacles especially in combination with the strong winter jets on Mars. Gravity waves on Mars were observed in the lower atmosphere [1,2] but are also expected to play a major role in the cooling of the thermosphere [3] and the polar warming [4]. A fundamental understanding of the possible source mechanisms is required to reveal the influence of small scale gravity waves on the global atmospheric circulation. Radio occultation profiles from the MaRS experiment on Mars Express [5] with their exceptionally high vertical resolution can be used to study small-scale vertical gravity waves and their global distribution in the lower atmosphere from the planetary boundary layer up to 40 km altitude. Atmospheric instabilities, which are clearly identified in the data, are used to gain further insight into possible atmospheric processes contributing to the excitation of gravity waves. [1] Creasey, J. E., et al.,(2006), Geophys. Res. Lett., 33, L01803, doi:10.1029/2005GL024037. [2]Tellmann, S., et al.(2013), J. Geophys. Res. Planets, 118, 306-320, doi:10.1002/jgre.20058. [3]Medvedev, A. S., et al.(2015), J. Geophys. Res. Planets, 120, 913-927. doi:10.1002/2015JE004802.[4] Barnes, J. R. (1990), J. Geophys. Res., 95, B2, 1401-1421. [5] Pätzold, M., et al. (2016), Planet. Space Sci., 127, 44 - 90.

Ozone and secondary organic aerosol production by interaction between and organophosphorous pesticide and biogenic VOCs mixture

NASA Astrophysics Data System (ADS)

Borrás, Esther; Ródenas, Mila; Vera, Teresa; Muñoz, Amalia

2017-04-01

Pesticides are the chemical compounds most widely used worldwide, and their toxicological characteristics can have harmful effects on human health. The entry into the atmosphere of pesticides occurs during application or subsequent processes. Once they are emitted, they can be distributed in the gas phase or particulate phase. However, most of them are in both phases, since they are semi-volatile compounds. As with other organic compounds, pesticides' removal in the atmosphere can be mainly accomplished by wet or dry deposition, by photolysis or by reaction with hydroxyl radicals (OH), nitrate radicals (NO3) and ozone (O3) [1]. All these processes give rise to the formation of other products, which could become more harmful than the starting compounds. It is therefore necessary to know all these processes to estimate the impact of pesticides in the atmosphere. In addition, it is important to study how the pesticides interact with organic compounds naturally emitted by crops and their possible impact on the formation of secondary organic aerosols, ozone and other compounds. In this work, the gas phase atmospheric degradation of an organothiophosphate insecticide has been investigated at the large outdoor European Photoreactor (EUPHORE) in the presence of a biogenic compound mixture typical from orange trees emissions. Its photolysis has been studied under sunlight conditions, in the presence of different concentration ratios of chlorpyrifos and biogenic VOCs mixture and in the absence of initial inorganic seeds. Reaction with ozone has also been studied. Gaseous phase compounds were determined by a Fourier Transform Infrared Spectrometer (FTIR), Proton Transfer Reaction - Mass Spectrometry (PTRMS), Solid Phase Microextraction (SPME) coupled to gas chromatography-mass spectrometry (GCMS) and NOx, O3 and SO2 monitors. Aerosol mass concentration was measured using a scanning mobility particle sizer (SMPS) and a tapered element oscillating monitor (TEOM). Chemical characterization of degradation products were done by using different off-line analysis with SPME, C18 cartridges and filters plus derivatization and subsequent analysis by GCMS. The results show that the combination of pesticide and biogenic compounds increase the SOA and O3 formation, being, in combination, high contributors to photochemical smog. This study contributes providing useful data about atmospheric degradation processes of pesticides. Knowledge of the specific degradation products, including the formation of secondary particulate matter and ozone, could complete the assessment of their potential impact. The understanding of atmospheric reactions should help to estimate the expected formation of gas and/or particulate products in the troposphere for each pesticide. Hence, these results can contribute to the selection of environmentally sustainable strategies against plagues. Acknowledgements The authors wish to thank the EUPHORE staff. Ministerio de Economía y Competitividad for IMPLACAVELES (CGL2013-49093-C2-1-R) and Generalitat Valenciana for the DESESTRES- Prometeo II project are acknowledged. Fundación CEAM is partly supported by Generalitat Valenciana - Spain. References [1] R. Atkinson, et al. Water, Air and Soil Pollution 115, 219-243 (1999).

Mechanisms and Effects of Summertime Transport of African Dust Through the Tokar Mountain Gap to the Red Sea and Arabian Peninsula

NASA Astrophysics Data System (ADS)

Kalenderski, S.; Stenchikov, G. L.

2015-12-01

Very high dust loading over the Red Sea region in summer strongly affects the nutrition balance and thermal and dynamic regimes of the sea. The observations suggest that small-scale local dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand and quantify these processes we present here the first high resolution modeling study of the dust outbreak phenomena in June 2012 over East Africa, the Red Sea, and the Arabian Peninsula using the WRF-Chem model. We identified several dust generating dynamical processes that range from convective to synoptic scales, including: synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea most of the dust transport occurs beyond 2 km above ground level and is strengthened by a pressure gradient formed by low pressure over the eastern Mediterranean and high pressure over the Arabian Peninsula. Across the central and southern parts of the Red Sea dust is mostly transported below 2 km height. During the study period dust is a dominant contributor (87%) to aerosol optical depth (AOD), producing a domain average cooling effect of -12.1 W m-2 at surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. WRF-Chem simulations demonstrate that both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. During the dust outbreak 49.2 Tg of dust deposits within the calculation domain, which is approximately 90% of the total dust emission of 54.5 Tg. Model results compare well with available ground-based and satellite observations but generally underestimate the observed AOD maximum values.

Study on wet scavenging of atmospheric pollutants in south Brazil

NASA Astrophysics Data System (ADS)

Wiegand, Flavio; Pereira, Felipe Norte; Teixeira, Elba Calesso

2011-09-01

The present paper presents the study of in-cloud and below-cloud SO 2 and SO 42-scavenging processes by applying numerical models in the Candiota region, located in the state of Rio Grande do Sul, South Brazil. The BRAMS (Brazilian Regional Atmospheric Modeling System) model was applied to simulate the vertical structure of the clouds, and the B.V.2 (Below-Cloud Beheng Version 2) scavenging model was applied to simulate in-cloud and below-cloud scavenging processes of the pollutants SO 2 and SO 42-. Five events in 2004 were selected for this study and were sampled at the Candiota Airport station. The concentrations of SO 2 and SO 42- sampled in the air and the simulated meteorological parameters of rainfall episodes were used as input data in the B.V.2, which simulates raindrop interactions associated with the scavenging process. Results for the Candiota region showed that in-cloud scavenging processes were more significant than below-cloud scavenging processes for two of the five events studied, with a contribution of approximately 90-100% of SO 2 and SO 42- concentrations in rainwater. A few adjustments to the original version of B.V.2 were made to allow simulation of scavenging processes in several types of clouds, not only cumulus humilis and cumulus congestus.

The Influence of Atmosphere-Ocean Interaction on MJO Development and Propagation

DTIC Science & Technology

2014-09-30

evaluate modeling results and process studies. The field phase of this project is associated with DYNAMO , which is the US contribution to the...influence on ocean temperature 4. Extended run for DYNAMO with high vertical resolution NCOM RESULTS Summary of project results The work funded...model experiments of the November 2011 MJO – the strongest MJO episode observed during the DYNAMO . The previous conceptual model that was based on TOGA

CONFERENCES AND SYMPOSIA: Long-lived light phenomena in the atmosphere

NASA Astrophysics Data System (ADS)

Smirnov, Boris M.

1994-05-01

The state of knowledge of long-lived light phenomena in the atmosphere is reviewed in the light of contributions to the International Interdisciplinary Congress on Unsolved Problems of Atmospheric Electricity, September 1993, Salzburg, Austria; and the First International Workshop on Unidentified Atmospheric Light Phenomena, March 1994, Hessdalen, Norway.

Investigation of the Physical Processes Governing Large-Scale Tracer Transport in the Stratosphere and Troposphere

NASA Technical Reports Server (NTRS)

Selkirk, Henry B.

2001-01-01

This report summarizes work conducted from January 1996 through April 1999 on a program of research to investigate the physical mechanisms that underlie the transport of trace constituents in the stratosphere-troposphere system. The primary scientific goal of the research has been to identify the processes which transport air masses within the lower stratosphere, particularly between the tropics and middle latitudes. This research was conducted in collaboration with the Subsonic Assessment (SASS) of the NASA Atmospheric Effects of Radiation Program (AEAP) and the Upper Atmospheric Research Program (UARP). The SASS program sought to understand the impact of the present and future fleets of conventional jet traffic on the upper troposphere and lower stratosphere, while complementary airborne observations under UARP seek to understand the complex interactions of dynamical and chemical processes that affect the ozone layer. The present investigation contributed to the goals of each of these by diagnosing the history of air parcels intercepted by NASA research aircraft in UARP and AEAP campaigns. This was done by means of a blend of trajectory analyses and tracer correlation techniques.

Mass loading in the solar wind interaction with Venus and Mars

NASA Astrophysics Data System (ADS)

Breus, T. K.; Bauer, S. J.; Krymskii, A. M.; Mitnitskii, V. Ya.

1989-03-01

An analysis of available experimental data and theoretical concepts indicates that the interaction of the solar wind (SW) on the subsolar side with Venus, which has no intrinsic magnetic field, and with Mars, which has a small intrinsic magnetic field, is determined by the solar wind dynamic pressure with a contribution from the neutral planetary atmosphere to this interaction. The pattern of the SW interaction with these planets is different in principle for high and low dynamic pressures of the SW and is related to the varying intensity of ion formation processes (the SW Mass loading effect) in the vicinity of the SW obstacle boundary, which moves for different SW dynamic pressures into regions of different neutral atmosphere density. For moderate or high SW dynamic pressures, the subsolar Martian magnetosphere is also affected by this process. Results of numerical simulations of the SW-Mars interaction for a magnetospheric obstacle boundary at an altitude of 300 km are presented. To estimate the relative role of photoionization and charge exchange processes and their effect on the shock front position, different versions of the mass loading effect were separately calculated.

Improved Time to Publication in Journal of Geophysical Research-Atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Gouw, Joost A.; Ghan, Steven J.; Pryor, Sara

Timely publication of manuscripts is important to authors and readers. AGU has significantly accelerated both the review and production processes for the Journal of Geophysical Research-Atmospheres (JGR-Atmospheres). Via a number of mechanisms (e.g., shortening the time allotted for reviewer selection, manuscript reviews, and revisions), the mean time to first decision has been decreased from 98 days in 2007 to 50 days in 2011, and the mean time to final decision has been decreased from 132 days in 2007 to 71 days in 2011. By implementing a new content management system, adjusting the workflow for improved efficiency, requesting authors to proofreadmore » their manuscripts quicker, and improving monitoring and follow-up to author and vendor queries, the mean production time from manuscript acceptance to publication has been decreased from 128 days in 2010 to only 56 days in 2012. Thus, in the past few years the mean time to publication of JGRAtmospheres has been cut in half. These milestones have been achieved with no loss of quality of presentation or content. In addition, online posting of "papers in press" on JGR-Atmosphere’s home page typically occurs within a few days after acceptance. JGR-Atmospheres editors thank manuscript reviewers, authors, and AGU staff who have greatly contributed to the more timely review and publication processes. This information will be updated periodically on the JGR-Atmospheres home page. A chart showing the average time from acceptance to publication for all of AGU’s journals is available at http://www.agu.org/pubs/pdf/31May2012_Timeliness_Chart.pdf.« less

Sources, solubility, and acid processing of aerosol iron and phosphorous over the South China Sea: East Asian dust and pollution outflows vs. Southeast Asian biomass burning

NASA Astrophysics Data System (ADS)

Hsu, S.-C.; Gong, G.-C.; Shiah, F.-K.; Hung, C.-C.; Kao, S.-J.; Zhang, R.; Chen, W.-N.; Chen, C.-C.; Chou, C. C.-K.; Lin, Y.-C.; Lin, F.-J.; Lin, S.-H.

2014-08-01

Iron and phosphorous are essential to marine microorganisms in vast regions in oceans worldwide. Atmospheric inputs are important allochthonous sources of Fe and P. The variability in airborne Fe deposition is hypothesized to serve an important function in previous glacial-interglacial cycles, contributing to the variability in atmospheric CO2 and ultimately the climate. Understanding the mechanisms underlying the mobilization of airborne Fe and P from insoluble to soluble forms is critical to evaluate the biogeochemical effects of these elements. In this study, we present a robust power-law correlation between fractional Fe solubility and non-sea-salt-sulfate / Total-Fe (nss-sulfate / FeT) molar ratio independent of distinct sources of airborne Fe of natural and/or anthropogenic origins over the South China Sea. This area receives Asian dust and pollution outflows and Southeast Asian biomass burning. This correlation is also valid for nitrate and total acids, demonstrating the significance of acid processing in enhancing Fe mobilization. Such correlations are also found for P, yet source dependent. These relationships serve as straightforward parameters that can be directly incorporated into available atmosphere-ocean coupling models that facilitate the assessment of Fe and P fertilization effects. Although biomass burning activity may supply Fe to the bioavailable Fe pool, pyrogenic soils are possibly the main contributors, not the burned plants. This finding warrants a multidisciplinary investigation that integrates atmospheric observations with the resulting biogeochemistry in the South China Sea, which is influenced by atmospheric forcings and nutrient dynamics with monsoons.

A local heat transfer analysis of lava cooling in the atmosphere: application to thermal diffusion-dominated lava flows

NASA Astrophysics Data System (ADS)

Neri, Augusto

1998-05-01

The local cooling process of thermal diffusion-dominated lava flows in the atmosphere was studied by a transient, one-dimensional heat transfer model taking into account the most relevant processes governing its behavior. Thermal diffusion-dominated lava flows include any type of flow in which the conductive-diffusive contribution in the energy equation largely overcomes the convective terms. This type of condition is supposed to be satisfied, during more or less extended periods of time, for a wide range of lava flows characterized by very low flow-rates, such as slabby and toothpaste pahoehoe, spongy pahoehoe, flow at the transition pahoehoe-aa, and flows from ephemeral vents. The analysis can be useful for the understanding of the effect of crust formation on the thermal insulation of the lava interior and, if integrated with adequate flow models, for the explanation of local features and morphologies of lava flows. The study is particularly aimed at a better knowledge of the complex non-linear heat transfer mechanisms that control lava cooling in the atmosphere and at the estimation of the most important parameters affecting the global heat transfer coefficient during the solidification process. The three fundamental heat transfer mechanisms with the atmosphere, that is radiation, natural convection, and forced convection by the wind, were modeled, whereas conduction and heat generation due to crystallization were considered within the lava. The magma was represented as a vesiculated binary melt with a given liquidus and solidus temperature and with the possible presence of a eutectic. The effects of different morphological features of the surface were investigated through a simplified description of their geometry. Model results allow both study of the formation in time of the crust and the thermal mushy layer underlying it, and a description of the behavior of the temperature distribution inside the lava as well as radiative and convective fluxes to the atmosphere. The analysis, performed by using parameters typical of Etnean lavas, particularly focuses on the non-intuitive relations between superficial cooling effects and inner temperature distribution as a function of the major variables involved in the cooling process. Results integrate recent modelings and measurements of the cooling process of Hawaiian pahoehoe flow lobes by Hon et al. (1994) and Keszthelyi and Denlinger (1996) and highlight the critical role played by surface morphology, lava thermal properties, and crystallization dynamics. Furthermore, the reported description of the various heat fluxes between lava and atmosphere can be extended to any other type of lava flows in which atmospheric cooling is involved.

[Medical bioclimatology: aspects of the historical evolution, with special reference to the contribution of Piedmontese scientists].

PubMed

Cremona, G F

1982-01-01

A short historical review on medical-meteorological and environmental research is presented. It is particularly stressed the contribution by piedmontese scientists of the XVIII century to investigations about the atmospheric electricity (Beccaria and Gardini) and the relations between diseases and atmospheric factors (Somis, Vassalli Eandi, Mullatera).

How salt lakes affect atmospheric new particle formation: A case study in Western Australia.

PubMed

Kamilli, K A; Ofner, J; Krause, T; Sattler, T; Schmitt-Kopplin, P; Eitenberger, E; Friedbacher, G; Lendl, B; Lohninger, H; Schöler, H F; Held, A

2016-12-15

New particle formation was studied above salt lakes in-situ using a mobile aerosol chamber set up above the salt crust and organic-enriched layers of seven different salt lakes in Western Australia. This unique setup made it possible to explore the influence of salt lake emissions on atmospheric new particle formation, and to identify interactions of aqueous-phase and gas-phase chemistry. New particle formation was typically observed at enhanced air temperatures and enhanced solar irradiance. Volatile organic compounds were released from the salt lake surfaces, probably from a soil layer enriched in organic compounds from decomposed leaf litter, and accumulated in the chamber air. After oxidation of these organic precursor gases, the reaction products contributed to new particle formation with observed growth rates from 2.7 to 25.4nmh -1 . The presence of ferrous and ferric iron and a drop of pH values in the salt lake water just before new particle formation events indicated that organic compounds were also oxidized in the aqueous phase, affecting the new particle formation process in the atmosphere. The contribution of aqueous-phase chemistry to new particle formation is assumed, as a mixture of hundreds of oxidized organic compounds was characterized with several analytical techniques. This chemically diverse composition of the organic aerosol fraction contained sulfur- and nitrogen-containing organic compounds, and halogenated organic compounds. Coarse mode particles were analyzed using electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. Ultra-high resolution mass spectrometry was applied to analyze filter samples. A targeted mass spectral analysis revealed the formation of organosulfates from monoterpene precursors and two known tracers for secondary organic aerosol formation from atmospheric oxidation of 1,8-cineole, which indicates that a complex interplay of aqueous-phase and gas-phase oxidation of monoterpenes contributes to new particle formation in the investigated salt lake environment. Copyright © 2016. Published by Elsevier B.V.

Snow-atmosphere coupling and its impact on temperature variability and extremes over North America

NASA Astrophysics Data System (ADS)

Diro, G. T.; Sushama, L.; Huziy, O.

2018-04-01

The impact of snow-atmosphere coupling on climate variability and extremes over North America is investigated using modeling experiments with the fifth generation Canadian Regional Climate Model (CRCM5). To this end, two CRCM5 simulations driven by ERA-Interim reanalysis for the 1981-2010 period are performed, where snow cover and depth are prescribed (uncoupled) in one simulation while they evolve interactively (coupled) during model integration in the second one. Results indicate systematic influence of snow cover and snow depth variability on the inter-annual variability of soil and air temperatures during winter and spring seasons. Inter-annual variability of air temperature is larger in the coupled simulation, with snow cover and depth variability accounting for 40-60% of winter temperature variability over the Mid-west, Northern Great Plains and over the Canadian Prairies. The contribution of snow variability reaches even more than 70% during spring and the regions of high snow-temperature coupling extend north of the boreal forests. The dominant process contributing to the snow-atmosphere coupling is the albedo effect in winter, while the hydrological effect controls the coupling in spring. Snow cover/depth variability at different locations is also found to affect extremes. For instance, variability of cold-spell characteristics is sensitive to snow cover/depth variation over the Mid-west and Northern Great Plains, whereas, warm-spell variability is sensitive to snow variation primarily in regions with climatologically extensive snow cover such as northeast Canada and the Rockies. Furthermore, snow-atmosphere interactions appear to have contributed to enhancing the number of cold spell days during the 2002 spring, which is the coldest recorded during the study period, by over 50%, over western North America. Additional results also provide useful information on the importance of the interactions of snow with large-scale mode of variability in modulating temperature extreme characteristics.

Hydrologic processes in China and their association with summer precipitation anomalies

NASA Astrophysics Data System (ADS)

Chen, M.; Pollard, D.; Barron, E. J.

2005-01-01

A climate version of MM5 is applied to study hydrologic processes in China and their association with precipitation anomalies in 1980 and 1985, which are two anomalous years with opposite signs of summer precipitation anomalies. The study reveals that anomalous atmospheric moisture transport due to synoptic scale circulation was primarily responsible for initiating the anomalous wet (dry) summer in south-central China and dry (wet) summer in northeastern China in 1980 (1985). The recycling ratio (defined as contribution of local evaporation to total precipitation) ranges from less than 4% in northwestern China to more than 30% in south-central China at 1000 km space scale. Higher (lower) values of recycling ratio correspond to drier (wetter) summers in south-central China and northeastern China. However, the opposite is true in northwestern China. The recycling ratio reflects feedback among hydrologic components over both land and atmosphere. In northwestern China, these feedbacks will further sustain drought events that are triggered by anomalous synoptic scale disturbances, and turn them into prolonged and possibly perpetual phenomenon. However, in south-central China and northeastern China, these feedbacks help reducing severity of drought. The large differences in recycling ratio between the dry and wet years of 1980 and 1985 are indicative of powerful feedback between hydrologic and climatic processes, and imply that surface-atmosphere interaction in China is highly sensitive to climatic perturbation.

Nanoparticle-based concretes for the restoration of historical and contemporary buildings: a new way for CO2 reduction in architecture

NASA Astrophysics Data System (ADS)

Greco, Enrico; Ciliberto, Enrico; Verdura, Pietro Damiano; Lo Giudice, Elio; Navarra, Giuseppe

2016-05-01

The production of the cement is a highly energy-intensive process and contributes to the release of pollutants into the atmosphere due to both the chemical reactions occurring in the kiln and, in most cases, the burning of fossil fuels for power production. So, the reduction of the cement content in a concrete would be indirectly useful to decrease the pollutant emissions in the atmosphere. The results of our investigation indicate that the replacement levels of cement by the 4 % of nanoparticles show a positive increasing of many physical and chemical properties allowing a relevant saving of cement content inside a concrete mixture. The compressive strengths, tensile splitting, propagations of ultrasonic pulses and water permeability tests were investigated on different models and realistic structures by the ISO EN rules. The influence of the nanoparticles on physical and mechanical properties was measured at different ripening times. Both silica and iron oxides make cement pastes harder and accelerated hydration processes of the cements. A remarkable decreasing in water permeability was also observed showing that nanoconcretes can be used as innovative restoration systems for cement-based historical and contemporary artefacts in order to avoid carbonation processes. Moreover, a smaller quantity of cement binder inside the mortar causes relevant positive effects on the reduction of carbon dioxide emission in the atmosphere.

Aerosol-Monsoon Interaction, maintenance and variability of the Asian Tropopause Aerosol Layer (ATAL)

NASA Astrophysics Data System (ADS)

Yuan, C.; Lau, W. K. M.; Li, Z.

2016-12-01

In recent years, the discovery of the Asian Tropopause Aerosol Layer (ATAL) from NASA satellite observations has sparked much interests in research on its composition, origin and relationships to the transport processes of atmospheric constituents in the upper troposphere and lower stratosphere (UTLS) and the variability of the Asian Monsoon Anticyclone (AMA). In this paper, based on analysis of MERRA2 reanalysis data, we present results showing that: 1) water vapor, aerosols and chemical gases (BC, OC, dust and CO) originated for the earth surface contribute significantly to the composition of the ATAL during the Asian summer monsoon, 2) one of the major pathways is via the strong large-scale vertical motion, and convective ascent over the Northern Himalayan Foothills during the peak phase of the Indian monsoon, 3) once transported into the UTLS , atmospheric constituents are capped by the Tropopuase inversion Layer (TIL) and advected around within and in the vicinity of the AMA forming the ATAL, 4) the ATAL is modulated by UTLS transport processes which undergo intrinsic monsoon intraseasonal oscillations with 20-30 day quasi-periodicity, coupled to lower tropospheric monsoon dynamics and diabatic heating processes, 5) the pre-monsoon accumulation of absorbing aerosols (BC, OC and dust) over the Indo-Gangetic Plain is more than likely to play an important role in enhancing the UTLS transport of atmospheric constituents from the earth surface to the ATAL.

Collision and radiative processes in emission of atmospheric carbon dioxide

NASA Astrophysics Data System (ADS)

Smirnov, B. M.

2018-05-01

The peculiarities of the spectroscopic properties of CO2 molecules in air due to vibration-rotation radiative transitions are analyzed. The absorption coefficient due to atmospheric carbon dioxide and other atmospheric components is constructed within the framework of the standard atmosphere model, on the basis of classical molecular spectroscopy and the regular model for the spectroscopy absorption band. The radiative flux from the atmosphere toward the Earth is represented as that of a blackbody, and the radiative temperature for emission at a given frequency is determined with accounting for the local thermodynamic equilibrium, a small gradient of the tropospheric temperature and a high optical thickness of the troposphere for infrared radiation. The absorption band model with an absorption coefficient averaged over the frequency and line-by-line model are used for evaluating the radiative flux from the atmosphere to the Earth which values are nearby for these models and are equal W m‑2 for the contemporary concentration of atmospheric CO2 molecules and W m‑2 at its doubled value. The absorption band model is not suitable to calculate the radiative flux change at doubling of carbon dioxide concentration because averaging over oscillations decreases the range where the atmospheric optical thickness is of the order of one, and just this range determines this change. The line-by-line method gives the change of the global temperature K as a result of doubling the carbon dioxide concentration. The contribution to the global temperature change due to anthropogenic injection of carbon dioxide in the atmosphere, i.e. resulted from combustion of fossil fuels, is approximately 0.02 K now.

Atmospheric and oceanic excitation of decadal-scale Earth orientation variations

NASA Astrophysics Data System (ADS)

Gross, Richard S.; Fukumori, Ichiro; Menemenlis, Dimitris

2005-09-01

The contribution of atmospheric wind and surface pressure and oceanic current and bottom pressure variations during 1949-2002 to exciting changes in the Earth's orientation on decadal timescales is investigated using an atmospheric angular momentum series computed from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis project and an oceanic angular momentum series computed from a near-global ocean model that was forced by surface fluxes from the NCEP/NCAR reanalysis project. Not surprisingly, since decadal-scale variations in the length of day are caused mainly by interactions between the mantle and core, the effect of the atmosphere and oceans is found to be only about 14% of that observed. More surprisingly, it is found that the effect of atmospheric and oceanic processes on decadal-scale changes in polar motion is also only about 20% (x component) and 38% (y component) of that observed. Therefore redistribution of mass within the atmosphere and oceans does not appear to be the main cause of the Markowitz wobble. It is also found that on timescales between 10 days and 4 years the atmospheric and oceanic angular momentum series used here have very little skill in explaining Earth orientation variations before the mid to late 1970s. This is attributed to errors in both the Earth orientation observations prior to 1976 when measurements from the accurate space-geodetic techniques became available and to errors in the modeled atmospheric fields prior to 1979 when the satellite era of global weather observing systems began.

Under-estimated wave contribution to coastal sea-level rise

NASA Astrophysics Data System (ADS)

Melet, Angélique; Meyssignac, Benoit; Almar, Rafael; Le Cozannet, Gonéri

2018-03-01

Coastal communities are threatened by sea-level changes operating at various spatial scales; global to regional variations are associated with glacier and ice sheet loss and ocean thermal expansion, while smaller coastal-scale variations are also related to atmospheric surges, tides and waves. Here, using 23 years (1993-2015) of global coastal sea-level observations, we examine the contribution of these latter processes to long-term sea-level rise, which, to date, have been relatively less explored. It is found that wave contributions can strongly dampen or enhance the effects of thermal expansion and land ice loss on coastal water-level changes at interannual-to-multidecadal timescales. Along the US West Coast, for example, negative wave-induced trends dominate, leading to negative net water-level trends. Accurate estimates of past, present and future coastal sea-level rise therefore need to consider low-frequency contributions of wave set-up and swash.

Growing the Next Generation of Data Professionals at the National Center for Atmospheric Research

NASA Astrophysics Data System (ADS)

Hou, C. Y.; Worley, S. J.; Mayernik, M. S.

2017-12-01

As a federally funded research and development center by the National Science Foundation, being able to provide education in order to advance scientific research is a top priority at the National Center for Atmospheric Research (NCAR). Among the various education programs available at the NCAR, the Data Stewardship Engineering Team (DSET) is working with students and early career professionals from the Library and Information Science (LIS) discipline. This LIS group is passionate about learning more about how to optimize the value of research information and often have innovative ideas regarding how to meet current as well as emerging information needs. As a new data initiative that focuses on developing the next generation data services, the NCAR DSET and its Digital Asset Services Hub is a rich, practical environment that provides opportunities for attaining experience and growing dedicated data stewards for the atmospheric and geosciences. In this presentation, the authors will describe the NCAR DSET's new outreach program. We will highlight the process that we are using to engage students and early career information scientists/librarians. This process allows them to acquire practical, hands-on data management and curation skills specific to the Earth sciences by enabling them to participate in an interdisciplinary environment as well as contribute to collaborative activities. We will also discuss the factors that influenced the structuring of the program, and share the current results and lessons learned. Ultimately, we aim to strengthen the NCAR's educational contribution to and collaboration with the LIS discipline by: 1) documenting the experience and soliciting feedback regarding the ways in which we could further expand the mutual interests of Earth sciences and LIS education curricula, and 2) sharing the findings and impacts of the outreach program at NCAR with the education community.

Modeling biophysical/biogeochemical/ecological/ocean/atmosphere two-way interactions using NCEP CFS/SSiB5/TRIFFID/DAYCENT: challenge and promising

NASA Astrophysics Data System (ADS)

Xue, Y.; Liu, Y.; Cox, P. M.; De Sales, F.; Lee, J.; Marx, L.; Hartman, M. D.; Yang, R.; Parton, W. J.; Qiu, B.; Ek, M. B.

2016-12-01

Evaluations of several dynamic vegetation models' (DVM) performances in the offline experiments and in the CMIP5 simulations suggest that most of the DVMs substantially overestimate leaf area index (LAI) and length of the growing season, which contribute to overestimation in their coupled models' precipitation. These results suggest important deficiencies in today's DVMs but also show the importance of proper ecological processes in the Earth System Modeling. We have developed a water-carbon-energy balance-based ecosystem model (SSiB4/TRIFFID) and verified it with field and satellite measurement at seasonal to decadal and longer scales. In the global offline tests, the model was integrated from 1950 to 2010 driven by observed meteorological forcing. The simulated trend and decadal variabilities in surface ecosystem conditions (e.g., Plant functional types, LAI, GPP), and surface water and energy balances are analyzed; further experiments and analyses are carried to isolate the contribution due to elevated atmospheric carbon concentration, global warming, soil moisture, and climate variability. How nitrogen processes simulated by the DayCent model Climate Forecast System (CFS) model, which has consistently shown improvements in simulated atmospheric & ocean conditions compared with those runs with specified vegetation conditions. In an experiment, two parametrizations that calculate the mean water potential in soil layers, which affect transpiration and plants' mortality, are tested. It shows that these two methods have substantial impact on global decadal variability of precipitation and surface temperature, with even opposite signs over some regions in the worlds. These results show the uncertainty in DVM modeling with significant implication for the future prediction. It is imperative to evaluate DVMs with comprehensive observational data.

Role of Southern Ocean stratification in glacial atmospheric CO2 reduction

NASA Astrophysics Data System (ADS)

Kobayashi, H.; Oka, A.

2014-12-01

Paleoclimate proxy data at the glacial period shows high salinity of more than 37.0 psu in the deep South Atlantic. At the same time, data also indicate that the residence time of the water mass was more than 3000 years. These data implies that the stratification by salinity was stronger in the deep Southern Ocean (SO) in the Last Glacial Maximum (LGM). Previous studies using Ocean General Circulation Model (OGCM) fail to explain the low glacial atmospheric carbon dioxide (CO2) concentration at LGM. The reproducibility of salinity and water mass age is considered insufficient in these OGCMs, which may in turn affect the reproducibility of the atmospheric CO2concentration. In coarse-resolution OGCMs, The deep water is formed by unrealistic open-ocean deep convection in the SO. Considering these facts, we guessed previous studies using OGCM underestimated the salinity and water mass age at LGM. This study investigate the role of the enhanced stratification in the glacial SO on the variation of atmospheric CO2 concentration by using OGCM. In order to reproduce the recorded salinity of the deep water, relaxation of salinity toward value of recorded data is introduced in our OGCM simulations. It was found that deep water formation in East Antarctica is required for explaining the high salinity in the South Atlantic. In contrast, it is difficult to explain the glacial water mass age, even if we assume the situation vertical mixing is very weak in the SO. Contrary to previous estimate, the high salinity of the deep SO resulted in increase of Antarctic Bottom water (AABW) flow and decrease the residence time of carbon in the deep ocean, which increased atmospheric CO2 concentration. On the other hand, the weakening of the vertical mixing in the SO contributed to increase the vertical gradient of dissolved inorganic carbon (DIC), which decreased atmospheric CO2 concentration. Adding the contribution of the enhanced stratification in the glacial SO, we obtained larger reduction in atmospheric CO2 concentration than previous studies. However, we still fail to explain the full amplitude of recorded glacial reduction of atmospheric CO2 concentration. The carbonate compensation process, which is not incorporated in our simulations, might be required for further reduction in atmospheric CO2 concentration.

Methane sources in gas hydrate-bearing cold seeps: Evidence from radiocarbon and stable isotopes

USGS Publications Warehouse

Pohlman, J.W.; Bauer, J.E.; Canuel, E.A.; Grabowski, K.S.; Knies, D.L.; Mitchell, C.S.; Whiticar, Michael J.; Coffin, R.B.

2009-01-01

Fossil methane from the large and dynamic marine gas hydrate reservoir has the potential to influence oceanic and atmospheric carbon pools. However, natural radiocarbon (14C) measurements of gas hydrate methane have been extremely limited, and their use as a source and process indicator has not yet been systematically established. In this study, gas hydrate-bound and dissolved methane recovered from six geologically and geographically distinct high-gas-flux cold seeps was found to be 98 to 100% fossil based on its 14C content. Given this prevalence of fossil methane and the small contribution of gas hydrate (??? 1%) to the present-day atmospheric methane flux, non-fossil contributions of gas hydrate methane to the atmosphere are not likely to be quantitatively significant. This conclusion is consistent with contemporary atmospheric methane budget calculations. In combination with ??13C- and ??D-methane measurements, we also determine the extent to which the low, but detectable, amounts of 14C (~ 1-2% modern carbon, pMC) in methane from two cold seeps might reflect in situ production from near-seafloor sediment organic carbon (SOC). A 14C mass balance approach using fossil methane and 14C-enriched SOC suggests that as much as 8 to 29% of hydrate-associated methane carbon may originate from SOC contained within the upper 6??m of sediment. These findings validate the assumption of a predominantly fossil carbon source for marine gas hydrate, but also indicate that structural gas hydrate from at least certain cold seeps contains a component of methane produced during decomposition of non-fossil organic matter in near-surface sediment.

Anthropogenic atmospheric nickel emissions and its distribution characteristics in China.

PubMed

Tian, H Z; Lu, L; Cheng, K; Hao, J M; Zhao, D; Wang, Y; Jia, W X; Qiu, P P

2012-02-15

Nickel and its compounds are considered as potential human carcinogens, and atmospheric nickel is one of the major routes for human exposure. By applying the best available fuel-based or product-based emission factors and annual activity levels, a multiple-year comprehensive inventory of anthropogenic atmospheric nickel emissions in China is presented with temporal trend and spatial resolutions for the period of 1980-2009 from both fuels combustion sources and industrial producing processes. We estimate that the total atmospheric nickel emissions from all the sources have increased from 1096.07 t in 1980 to 3933.71 t in 2009, at an average annual growth rate of 4.5%. Therein, coal combustion is the leading source, attributing 63.4% of the national total nickel emissions in 2009; liquid fuels consumption ranks the second, contributing 12.4% of the totals; biofuels burning accounts for 8.4% and the remaining sources together contribute 15.8% of the totals. Significant spatial variations are demonstrated among provincial emissions and the most concentrated regions are the highly industrialized and densely populated areas like the Yangtze River Delta, the Pearl River Delta and the Beijing-Tianjin-Hebei region. Moreover, the overall uncertainties are estimated at -32.6%-37.7% by using Monte Carlo simulation, most of which come from non-ferrous metals smelting category, implying the urgent need for further investigation and field tests. This article may help to combat the increasing stress on air heavy metals pollution in China and provide useful information to calculate global mass balance models for hazardous trace elements. Copyright © 2011 Elsevier B.V. All rights reserved.

Ambient in-situ immersion freezing measurements - findings from the ZAMBIS 2014 field campaign for three ice nucleation techniques

NASA Astrophysics Data System (ADS)

Kohn, Monika; Atkinson, James D.; Lohmann, Ulrike; Kanji, Zamin A.

2015-04-01

To estimate the influence of clouds on the Earth's radiation budget, it is crucial to understand cloud formation processes in the atmosphere. A key process, which significantly affects cloud microphysical properties and the initiation of precipitation thus contributing to the hydrological cycle, is the prevailing type of ice nucleation mechanism. In mixed-phase clouds immersion freezing is the dominant ice crystal forming mechanism, whereby ice nucleating particles (INP) first act as cloud condensation nuclei (CCN) and are activated to cloud droplets followed by freezing upon supercooling. There are a number of experimental methods and techniques to investigate the ice nucleating ability in the immersion mode, however most techniques are offline for field sampling or only suitable for laboratory measurements. In-situ atmospheric studies are needed to understand the ice formation processes of 'real world' particles. Laboratory experiments simulate conditions of atmospheric processes like ageing or coating but are still idealized. Our method is able to measure ambient in-situ immersion freezing on single immersed aerosol particles. The instrumental setup consists of the recently developed portable immersion mode cooling chamber (PIMCA) as a vertical extension to the portable ice nucleation chamber (PINC, [1]), where the frozen fraction of activated aerosol particles are detected by the ice optical depolarization detector (IODE, [2]). Two additional immersion freezing techniques based on a droplet freezing array [3,4] are used to sample ambient aerosol particles either in a suspension (fraction larger ~0.6 μm) or on PM10-filters to compare different ice nucleation techniques. Here, we present ambient in-situ measurements at an urban forest site in Zurich, Switzerland held during the Zurich ambient immersion freezing study (ZAMBIS) in spring 2014. We investigated the ice nucleating ability of natural atmospheric aerosol with the PIMCA/PINC immersion freezing setup as well as a droplet freezing method on aerosol particles either collected in a suspension or on PM10-filters to obtain atmospheric IN concentrations based on the measured ambient aerosol. Investigation of physical properties (number and size distribution) and chemical composition as well as the meteorological conditions provide supplementary information that help to understand the nature of particles and air masses that contribute to immersion freezing. Acknowledgements We thank Hannes Wydler and Hansjörg Frei from ETH Zurich for their technical support. Furthermore, the authors want thank Franz Conen from the University of Basel for sharing equipment and training in the drop freezing experiment. References [1] Chou et al. (2011), Atmos. Chem. Phys., 11, 4725-4738. [2] Nicolet et al. (2010), Atmos. Chem. Phys., 10, 313-325. [3] Conen et al. (2012), Atmos. Meas. Tech., 5, 321-327. [4] Stopelli et al. (2014), Atmos. Meas. Tech., 7, 129-134.

Do contemporary (1980-2015) emissions determine the elemental carbon deposition trend at Holtedahlfonna glacier, Svalbard?

NASA Astrophysics Data System (ADS)

Ruppel, Meri M.; Soares, Joana; Gallet, Jean-Charles; Isaksson, Elisabeth; Martma, Tõnu; Svensson, Jonas; Kohler, Jack; Pedersen, Christina A.; Manninen, Sirkku; Korhola, Atte; Ström, Johan

2017-10-01

The climate impact of black carbon (BC) is notably amplified in the Arctic by its deposition, which causes albedo decrease and subsequent earlier snow and ice spring melt. To comprehensively assess the climate impact of BC in the Arctic, information on both atmospheric BC concentrations and deposition is essential. Currently, Arctic BC deposition data are very scarce, while atmospheric BC concentrations have been shown to generally decrease since the 1990s. However, a 300-year Svalbard ice core showed a distinct increase in EC (elemental carbon, proxy for BC) deposition from 1970 to 2004 contradicting atmospheric measurements and modelling studies. Here, our objective was to decipher whether this increase has continued in the 21st century and to investigate the drivers of the observed EC deposition trends. For this, a shallow firn core was collected from the same Svalbard glacier, and a regional-to-meso-scale chemical transport model (SILAM) was run from 1980 to 2015. The ice and firn core data indicate peaking EC deposition values at the end of the 1990s and lower values thereafter. The modelled BC deposition results generally support the observed glacier EC variations. However, the ice and firn core results clearly deviate from both measured and modelled atmospheric BC concentration trends, and the modelled BC deposition trend shows variations seemingly independent from BC emission or atmospheric BC concentration trends. Furthermore, according to the model ca. 99 % BC mass is wet-deposited at this Svalbard glacier, indicating that meteorological processes such as precipitation and scavenging efficiency have most likely a stronger influence on the BC deposition trend than BC emission or atmospheric concentration trends. BC emission source sectors contribute differently to the modelled atmospheric BC concentrations and BC deposition, which further supports our conclusion that different processes affect atmospheric BC concentration and deposition trends. Consequently, Arctic BC deposition trends should not directly be inferred based on atmospheric BC measurements, and more observational BC deposition data are required to assess the climate impact of BC in Arctic snow.

New insights into saline water evaporation from porous media: Complex interaction between evaporation rates, precipitation, and surface temperature

NASA Astrophysics Data System (ADS)

Shokri-Kuehni, Salomé M. S.; Vetter, Thomas; Webb, Colin; Shokri, Nima

2017-06-01

Understanding salt transport and deposition patterns during evaporation from porous media is important in many engineering and hydrological processes such as soil salinization, ecosystem functioning, and land-atmosphere interaction. As evaporation proceeds, salt concentration increases until it exceeds solubility limits, locally, and crystals precipitate. The interplay between transport processes, crystallization, and evaporation influences where crystallization occurs. During early stages, the precipitated salt creates an evolving porous structure affecting the evaporation kinetics. We conducted a comprehensive series of experiments to investigate how the salt concentration and precipitation influence evaporation dynamics. Our results illustrate the contribution of the evolving salt crust to the evaporative mass losses. High-resolution thermal imaging enabled us to investigate the complex temperature dynamics at the surface of precipitated salt, providing further confirmation of salt crust contribution to the evaporation. We identify different phases of saline water evaporation from porous media with the corresponding dominant mechanisms in each phase and extend the physical understanding of such processes.

Differentiating atmospheric and mineral sources of sulfur during snowmelt using δ 34S, 35S activity, and δ 18O of sulfate and water as tracers

NASA Astrophysics Data System (ADS)

Shanley, J. B.; Mayer, B.; Mitchell, M. J.; Michel, R. L.; Bailey, S.; Kendall, C.

2003-12-01

The biogeochemical cycling of sulfur was studied during the 2000 snowmelt at Sleepers River Research Watershed in northeastern Vermont, USA using a combination of isotopic, chemical, and hydrometric measurements. The snowpack and 10 streams of varying size and land use were sampled for sulfate concentrations and isotopic analyses of 35S, δ 34S, and δ 18O of sulfate. Values of δ 18O of water were measured at one of the streams. Apportionment of atmospheric and mineral S sources based on δ 34S was possible at 7 of the 10 streams. Weathering of S-containing minerals was a major contributor to sulfate flux in streamwater, but atmospheric contributions exceeded 50% in several of the streams at peak snowmelt and averaged 41% overall. In contrast, δ 18Osulfate values of streamwater remained significantly lower than those of atmospheric sulfate throughout the melt period, indicating that atmospheric sulfate undergoes microbial redox reactions in the soil that replace the oxygen of atmospheric sulfate with isotopically lighter oxygen from soil water. Streamwater 35S activities were low relative to those of the snowpack; the youngest 35S-ages of the atmospheric S component in each of the 7 streams ranged from 184 to 320 days. Atmospheric S contributions to streamwater, as determined by δ 34S values, co-varied both with 35S activity and new water contributions as determined by δ 18Owater. However, the δ 18Osulfate and 35S ages clearly show that this new water carries very little of the atmospheric sulfate entering with the current snowmelt to the stream. Most incoming atmospheric sulfate first cycles through the organic soil S pool and ultimately reaches the stream as pedogenic sulfate.

Comparative evaluation of the impact of GRAPES and MM5 meteorology on CMAQ prediction over Pearl River Delta, China

NASA Astrophysics Data System (ADS)

Deng, T.; Chen, Y.; Wan, Q.

2017-12-01

The Community Multiscale Air Quality (CMAQ) model was utilized for forecasting air quality over the Pearl River Delta (PRD) region from December 2013 to January 2014. The pollution forecasting performance of CMAQ coupled with the two different meteorological models, the Global/Regional Assimilation and Prediction System (GRAPES) and the 5th-generation Mesoscale Model (MM5), was assessed by combining observational data. The effect of meteorological factors and physical-chemical processes on forecast results was discussed through process analysis. The results showed that both models have similar good performance with better performance by GRAPES-CMAQ. GRAPES was superior in predicting the overall meteorological element variation tendencies but showed large deviations in atmospheric pressure and wind speed. It contributed to higher correlation coefficients of the pollutants with GRAPES-CMAQ, but with greater deviation. The underestimations of nitrate and ammonium salt contributed to the underestimations of Particle Matter (PM) and extinction coefficients. Surface layer SO2, CO and NO source emissions made the sole positive contribution. O3 originated mainly from horizontal and vertical transport and chemical processes were the main consumption item. On the contrary, NO2 derived mainly from chemical production.

Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

PubMed Central

Sparrow, Katy J.; Kessler, John D.; Southon, John R.; Garcia-Tigreros, Fenix; Schreiner, Kathryn M.; Ruppel, Carolyn D.; Miller, John B.; Lehman, Scott J.; Xu, Xiaomei

2018-01-01

In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere. PMID:29349299

Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

USGS Publications Warehouse

Sparrow, Katy J.; Kessler, John D.; Southon, John R.; Garcia-Tigreros, Fenix; Schreiner, Kathryn M.; Ruppel, Carolyn D.; Miller, John B.; Lehman, Scott J.; Xu, Xiaomei

2018-01-01

In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.

Solution plasma applications for the synthesis/modification of inorganic nanostructured materials and the treatment of natural polymers

NASA Astrophysics Data System (ADS)

Watthanaphanit, Anyarat; Saito, Nagahiro

2018-01-01

Reducing the use of toxic chemicals, production steps, and time consumption are important concerns for researchers and process engineers to contribute in the quest for an efficient process in any production. If an equipment setup is simple, the process additionally becomes more profitable. Combination of the mentioned requirements has opened up various applications of the solution plasma process (SPP) — a physical means of generating plasma through an electrical discharge in a liquid medium at atmospheric pressure and room temperature. This review shows the progress of scientific research on the applications of the SPP for the synthesis/modification of inorganic nanostructured materials and the treatment of natural polymers. Development achieved in each application is demonstrated.

Composition and mixing states of brown haze particle over the Himalayas along two transboundary south-north transects

NASA Astrophysics Data System (ADS)

Dong, Zhiwen; Kang, Shichang; Guo, Junming; Zhang, Qianggong; Wang, Xuejia; Qin, Dahe

2017-05-01

Pollutants that are usually transported from southern Asia to the Tibetan Plateau deposit on the Plateau surface, change snow albedo and thereby surface radiative flux. This results numerous climatic implications like as erratic monsoon, perturbation in hydrological cycle, etc. However, the accurate estimation of these climatic implications is not well understood, because the atmospheric pollution is a heterogeneous mixture of various particle types. Therefore, this part of climate research requires a detailed investigation of physical and chemical properties of atmospheric pollutants. This study aimed to examine the physical and chemical properties of atmospheric pollutants across the Himalayan regions along two transboundary south-north transects. The information of individual-particles was obtained using microscopy-based techniques that comprises transmission electron microscope (TEM) and Energy-dispersive X-ray spectrometer (EDX). Study capture the signatures of various types of atmospheric species such as black carbon (BC), mineral dust, fly ash, organic matter, sulfate, nitrite, ammonium, and NaCl. Microscopy-based techniques confirm that these particles were generally in mixing state, for example salt-coated particles accounting for 25-56% of the total particles in sampled locations. Our analysis shows that urban and rural locations are characterized with atmospheric particles which sourced from anthropogenic activities, whereas remote locations with those released from natural crustal. However, the relative contributions of anthropogenic particles were higher than that of particles released from natural crustal. The presence of such particles over remote locations of Himalayan region provides an evidence of prevailing atmospheric transport processes, which further need to be well understood. It is expected that this work would be helpful in understanding the regional atmospheric conditions and the transboundary transport process of haze particles. As these informations are of great importance in modeling studies, which further lead to improve understanding of haze particles climate effects.

Organic condensation: A vital link connecting aerosol formation to climate forcing (Invited)

NASA Astrophysics Data System (ADS)

Riipinen, I.; Pierce, J. R.; Yli-Juuti, T.; Nieminen, T.; Häkkinen, S.; Ehn, M.; Junninen, H.; Lehtipalo, K.; Petdjd, T. T.; Slowik, J. G.; Chang, R. Y.; Shantz, N. C.; Abbatt, J.; Leaitch, W. R.; Kerminen, V.; Worsnop, D. R.; Pandis, S. N.; Donahue, N. M.; Kulmala, M. T.

2010-12-01

Aerosol-cloud interactions represent the largest uncertainty in calculations of Earth’s radiative forcing. Number concentrations of atmospheric aerosol particles are in the core of this uncertainty, as they govern the numbers of cloud condensation nuclei (CCN) and influence the albedo and lifetime of clouds. Aerosols also impair air quality through their adverse effects on atmospheric visibility and human health. The ultrafine fraction (<100 nm) of atmospheric aerosol particles often dominates the total aerosol numbers, and nucleation of atmospheric vapours is one of the most important sources of these particles. To have climatic relevance, however, the freshly-nucleated particles need to grow in size, and consequently their climatic importance remains to be quantified (see Fig. 1). We combine observations from two continental sites (Egbert, Canada and Hyytiälä, Finland) to show that condensation of organic vapours is a crucial factor governing the lifetimes and climatic importance of the smallest atmospheric particles. We demonstrate that state-of-the-science organic gas-particle partitioning models fail to reproduce the observations; we propose a new modelling approach that is consistent with the measurements. Finally, we demonstrate the large sensitivity of climatic forcing of atmospheric aerosols to these interactions between organic vapours and the smallest atmospheric nanoparticles - highlighting the need for representing this process in global climate models. Figure 1. Organic emissions and the dynamic processes governing the climatic importance of ultrafine aerosol. Condensable vapours are produced upon oxidation of volatile organic compounds (VOCs) and can 1) nucleate to form new small particles; 2) grow freshly formed particles to larger sizes and increase their probability to serve as CCN; 3) condense on the background aerosol (> 100 nm) and enhance the loss of ultrafine particles. Primary organic aerosol (POA) contributes to the large end of the aerosol size distribution, enhancing the scavenging of the ultrafine particles.

A steady-state continuous flow chamber for the study of daytime and nighttime chemistry under atmospherically relevant NO levels

NASA Astrophysics Data System (ADS)

Zhang, Xuan; Ortega, John; Huang, Yuanlong; Shertz, Stephen; Tyndall, Geoffrey S.; Orlando, John J.

2018-05-01

Experiments performed in laboratory chambers have contributed significantly to the understanding of the fundamental kinetics and mechanisms of the chemical reactions occurring in the atmosphere. Two chemical regimes, classified as high-NO vs. zero-NO conditions, have been extensively studied in previous chamber experiments. Results derived from these two chemical scenarios are widely parameterized in chemical transport models to represent key atmospheric processes in urban and pristine environments. As the anthropogenic NOx emissions in the United States have decreased remarkably in the past few decades, the classic high-NO and zero-NO conditions are no longer applicable to many regions that are constantly impacted by both polluted and background air masses. We present here the development and characterization of the NCAR Atmospheric Simulation Chamber, which is operated in steady-state continuous flow mode for the study of atmospheric chemistry under intermediate NO conditions. This particular chemical regime is characterized by constant sub-ppb levels of NO and can be created in the chamber by precise control of the inflow NO concentration and the ratio of chamber mixing to residence timescales. Over the range of conditions achievable in the chamber, the lifetime of peroxy radicals (RO2), a key intermediate from the atmospheric degradation of volatile organic compounds (VOCs), can be extended to several minutes, and a diverse array of reaction pathways, including unimolecular pathways and bimolecular reactions with NO and HO2, can thus be explored. Characterization experiments under photolytic and dark conditions were performed and, in conjunction with model predictions, provide a basis for interpretation of prevailing atmospheric processes in environments with intertwined biogenic and anthropogenic activities. We demonstrate the proof of concept of the steady-state continuous flow chamber operation through measurements of major first-generation products, methacrolein (MACR) and methyl vinyl ketone (MVK), from OH- and NO3-initiated oxidation of isoprene.

A Future Mars Environment for Science and Exploration

NASA Technical Reports Server (NTRS)

Green, J. L.; Hollingsworth, J. L.; Kahre, M. A.; Brain, D.; Airapetian, V.; Glocer, A.; Pulkkinen, A.; Dong, C.; Bamford, R.

2017-01-01

Today, Mars is arid and cold with a very thin atmosphere that has significant frozen and underground water resources. The thin atmosphere prevents liquid water from residing permanently on its surface and makes it difficult to land missions since it is not thick enough to completely facilitate a soft landing. In its past, under the influence of a significant greenhouse effect, Mars must have had a significant water ocean covering perhaps 30% of the northern hemisphere. Mars lost its protective magnetosphere and therefore much of its atmosphere around 3 Ga ago, due to the solar wind. The atmospheric loss into the solar wind is somewhat balanced by the outgassing of the Mars interior and crust that contributes to the existing atmosphere leading to a global-mean surface atmosphere of 6 mbar pressure currently. By using our extensive simulation tools and physics capabilities in Space Weather and Mars global climate modeling, we have started to explore the effects on Mars of placing an artificial magnetic dipole field at the Mars L1 Lagrange point putting Mars in a magnetotail. This situation then eliminates many of the solar-wind erosion processes that occur with the planet's ionosphere and upper atmosphere allowing the Martian atmosphere to grow in pressure and bulk temperature over time. Under thicker atmospheres, the global circulation patterns and seasonal changes are much different than at present. An enhanced atmosphere would: allow larger landed mass of equipment to the surface, shield against some cosmic and solar particle radiation, extend the ability for extraction, and provide "open air" greenhouses to exist for plant production, just to name a few. These new conditions on Mars would allow human explorers and researchers to study the planet in much greater detail and enable a truly profound new understanding of the habitability of this planet.

Probing the atmosphere with infrasound

NASA Technical Reports Server (NTRS)

Posmentier, E. S.; Donn, W. L.

1969-01-01

Recent studies are reported which have contributed to the knowledge of atmospheric structure and have established the practicality of infrasonic techniques for probing the atmosphere to heights of 120 km or more. Observations of a few types of infrasound are reviewed, and the theories used to account for the infrasound propagation and the deduced atmospheric structures are discussed.

Charm contribution to the atmospheric neutrino flux

NASA Astrophysics Data System (ADS)

Halzen, Francis; Wille, Logan

2016-07-01

We revisit the estimate of the charm particle contribution to the atmospheric neutrino flux that is expected to dominate at high energies because long-lived high-energy pions and kaons interact in the atmosphere before decaying into neutrinos. We focus on the production of forward charm particles which carry a large fraction of the momentum of the incident proton. In the case of strange particles, such a component is familiar from the abundant production of K+Λ pairs. These forward charm particles can dominate the high-energy atmospheric neutrino flux in underground experiments. Modern collider experiments have no coverage in the very large rapidity region where charm forward pair production dominates. Using archival accelerator data as well as IceCube measurements of atmospheric electron and muon neutrino fluxes, we obtain an upper limit on forward D¯0Λc pair production and on the associated flux of high-energy atmospheric neutrinos. We conclude that the prompt flux may dominate the much-studied central component and represent a significant contribution to the TeV atmospheric neutrino flux. Importantly, it cannot accommodate the PeV flux of high-energy cosmic neutrinos, or the excess of events observed by IceCube in the 30-200 TeV energy range indicating either structure in the flux of cosmic accelerators, or a presence of more than one component in the cosmic flux observed.

Error sources in the retrieval of aerosol information over bright surfaces from satellite measurements in the oxygen A band

NASA Astrophysics Data System (ADS)

Nanda, Swadhin; de Graaf, Martin; Sneep, Maarten; de Haan, Johan F.; Stammes, Piet; Sanders, Abram F. J.; Tuinder, Olaf; Pepijn Veefkind, J.; Levelt, Pieternel F.

2018-01-01

Retrieving aerosol optical thickness and aerosol layer height over a bright surface from measured top-of-atmosphere reflectance spectrum in the oxygen A band is known to be challenging, often resulting in large errors. In certain atmospheric conditions and viewing geometries, a loss of sensitivity to aerosol optical thickness has been reported in the literature. This loss of sensitivity has been attributed to a phenomenon known as critical surface albedo regime, which is a range of surface albedos for which the top-of-atmosphere reflectance has minimal sensitivity to aerosol optical thickness. This paper extends the concept of critical surface albedo for aerosol layer height retrievals in the oxygen A band, and discusses its implications. The underlying physics are introduced by analysing the top-of-atmosphere reflectance spectrum as a sum of atmospheric path contribution and surface contribution, obtained using a radiative transfer model. Furthermore, error analysis of an aerosol layer height retrieval algorithm is conducted over dark and bright surfaces to show the dependence on surface reflectance. The analysis shows that the derivative with respect to aerosol layer height of the atmospheric path contribution to the top-of-atmosphere reflectance is opposite in sign to that of the surface contribution - an increase in surface brightness results in a decrease in information content. In the case of aerosol optical thickness, these derivatives are anti-correlated, leading to large retrieval errors in high surface albedo regimes. The consequence of this anti-correlation is demonstrated with measured spectra in the oxygen A band from the GOME-2 instrument on board the Metop-A satellite over the 2010 Russian wildfires incident.

The Sample Analysis at Mars Investigation and Instrument Suite

NASA Technical Reports Server (NTRS)

Mahaffy, Paul; Webster, Chris R.; Cabane, M.; Conrad, Pamela G.; Coll, Patrice; Atreya, Sushil K.; Arvey, Robert; Barciniak, Michael; Benna, Mehdi; Bleacher, L.;

Plasma Clouds and Snowplows: Bulk Plasma Escape from Mars Observed by MAVEN

NASA Technical Reports Server (NTRS)

Halekas, J. S.; Brain, D. A.; Ruhunusiri, S.; McFadden, J. P.; Mitchell, D. L.; Mazelle, C.; Connerney, J. E. P.; Harada, Y.; Hara, T.; Espley, J. R.;

Atmospheric bulk deposition of dissolved nitrogen, phosphorus and silicate in the Gulf of Gabès (South Ionian Basin); implications for marine heterotrophic prokaryotes and ultraphytoplankton

NASA Astrophysics Data System (ADS)

Khammeri, Yosra; Hamza, Ismail Sabeur; Zouari, Amel Bellaaj; Hamza, Asma; Sahli, Emna; Akrout, Fourat; Ben Kacem, Mohamed Yassine; Messaoudi, Sabri; Hassen, Malika Bel

2018-05-01

Monthly variability of atmospheric deposition of dissolved nitrogen, phosphorus and silicate was assessed during the year period from June 2014 to May 2015 in the Gulf of Gabès, situated near the most active source of dust. Nutrient concentrations, ultraphytoplankton <10 μm and heterotrophic prokaryotes abundances were simultaneously investigated in the surface coastal water near the sampling site. Results showed that most of the bulk nutrient deposition (more than 66%) occurred during wet season, from October to February, characterized by air masses originating from the Tunisian desert. Dissolved Inorganic Nitrogen (DIN) deposition was very low, whereas Dissolved Inorganic Phosphorus (DIP) bulk deposition was within the range of that observed in the Eastern Mediterranean. High organic nitrogen (30.47%) and phosphorus (83,5%) content contributed to the bulk nitrogen and phosphorus deposition respectively. Months marked by high deposition were accompanied by an increase of carbon biomass from picophytoplankton, Synecococcus and heterotrophic prokaryotes while nanophytoplankton biomass decreased from 62.38% to 43.39% towards the wet season. During the wet season, heterotrophic prokaryotes become the first contributors to the carbon biomass in the surface water. This suggests a possible contribution of bacteria to the organic nutrient pool driven by atmospheric deposition or/and a reinforcement of the heterotrophic character of the system due to the organic content mineralization processes.

Atmospheric emission characterization of Marcellus shale natural gas development sites.

PubMed

Goetz, J Douglas; Floerchinger, Cody; Fortner, Edward C; Wormhoudt, Joda; Massoli, Paola; Knighton, W Berk; Herndon, Scott C; Kolb, Charles E; Knipping, Eladio; Shaw, Stephanie L; DeCarlo, Peter F

2015-06-02

Limited direct measurements of criteria pollutants emissions and precursors, as well as natural gas constituents, from Marcellus shale gas development activities contribute to uncertainty about their atmospheric impact. Real-time measurements were made with the Aerodyne Research Inc. Mobile Laboratory to characterize emission rates of atmospheric pollutants. Sites investigated include production well pads, a well pad with a drill rig, a well completion, and compressor stations. Tracer release ratio methods were used to estimate emission rates. A first-order correction factor was developed to account for errors introduced by fenceline tracer release. In contrast to observations from other shale plays, elevated volatile organic compounds, other than CH4 and C2H6, were generally not observed at the investigated sites. Elevated submicrometer particle mass concentrations were also generally not observed. Emission rates from compressor stations ranged from 0.006 to 0.162 tons per day (tpd) for NOx, 0.029 to 0.426 tpd for CO, and 67.9 to 371 tpd for CO2. CH4 and C2H6 emission rates from compressor stations ranged from 0.411 to 4.936 tpd and 0.023 to 0.062 tpd, respectively. Although limited in sample size, this study provides emission rate estimates for some processes in a newly developed natural gas resource and contributes valuable comparisons to other shale gas studies.

Investigating Elevated Concentrations of Hydrogen in the LAX region

NASA Astrophysics Data System (ADS)

Rund, P.; Hughes, S.; Blake, D. R.

2017-12-01

The growing interest in hydrogen (H2) fuel cell vehicles has created a need to study the atmospheric H2 budget. While there is resounding agreement that hydrogen would escape into the atmosphere due to fuel transport/storage processes, there is disagreement over the amount that would be leaked in a hydrogen fuel economy. Leakage rate estimates range from 2% to 10% for total hydrogen production and transport. A hydrogen based energy infrastructure seems a viable clean alternative to oil because, theoretically, the only waste products are H2O and heat. However, hydrogen leads to the formation of water vapor, polar stratospheric clouds, and a decrease in stratospheric temperatures, which contribute to the depletion of stratospheric ozone. Whole air samples (WAS) collected aboard the NASA Sherpa C-23 during the Student Airborne Research Program (SARP) showed elevated concentrations of hydrogen near LAX (950 ± 110 ppbv) compared to global average concentrations of 560 ± 20 ppbv. Trace gas analysis along with wind trajectories obtained with the NOAA HySPLIT models indicate that the source of elevated mixing ratios was leakage from H2 fuel stations in the surrounding areas. Correlation and ratio analyses eliminate the potential for common photochemical sources of H2 in the LAX area. This project could elucidate new and potential factors that contribute to the global atmospheric hydrogen budget.

Monitoring gas concentrations in environmental and atmospheric applications using tunable diode lasers

NASA Astrophysics Data System (ADS)

Awtry, Andrew R.

Two atmospheric chemistry processes that contribute to environmental concerns have been explored using mid-infrared, lead-salt diode lasers. Tunable diode laser absorption spectroscopy was used to determine concentrations of both NF3 and NH3. The focus of the NF3 research was to determine the magnitude of the nu1 absorption band in order to determine the effects of this molecule on global warming. Deposition velocity is a proportionality constant between concentration and vertical flux to a surface. The magnitude of this constant for NH 3 depositing onto water is experimentally determined using both a small cell (425 mL) and a large chamber (335 L). The results from the chamber are then incorporated into a model in an attempt to better understand the atmospheric contribution to aqueous concentrations. Near-infrared diode lasers were used in both integrated cavity output spectroscopy and cavity ringdown spectroscopy in an attempt to develop an air monitoring sensor. The following experiments were then performed determine the sensitivity, durability and dynamic range of these two techniques: flame characterization of HCN and C2H2 in a flame from a Wolfhard-Parker burner, obtaining isolated absorption features of CO, CO2, H 2O, HCN, NH3, CH4, and C2H4 in order to create calibration curves and determine detection limits, CO 2 classroom measurements, and CO2 isotope ratio measurements.

Characterising the influence of atmospheric mixing state on Urban Heat Island Intensity using Radon-222

NASA Astrophysics Data System (ADS)

Chambers, Scott D.; Podstawczyńska, Agnieszka; Williams, Alastair G.; Pawlak, Włodzimierz

2016-12-01

Characterisation of the effects of varying atmospheric mixing states (stability) in urban climate studies has historically been hampered by problems associated with the complexity of the urban environment, representativity of measurement techniques, and the logistical and financial burdens of maintaining multiple long-term comprehensive measurement sites. These shortcomings, together with a lack of a consistent measurement approach, have limited our ability to understand the physical processes contributing to the urban heat island effect. In this study, we analyse 4 years of continuous hourly near-surface meteorological and atmospheric radon data from an urban-rural site pair in central Poland. A recently-developed radon-based stability classification technique, previously developed for urban pollution characterisation, is employed to characterise the Urban Heat Island Intensity (UHII) and other climatic factors over the full diurnal cycle by season and atmospheric mixing state. By characterising the UHII over a range of atmospheric mixing states in a statistically robust way, this technique provides an effective tool for assessing the efficacy of mitigation measures for urban climate effects in a consistent way over timescales of years to decades. The consistency of approach, ease of application, and unprecedented clarity of findings, provide a strong argument for atmospheric radon observations to be included as part of the 'standard measurement suite' for urban climate monitoring networks for non-coastal cities.

TOWARDS OPERATIONAL FORECASTING OF LOWER ATMOSPHERE EFFECTS ON THE UPPER ATMOSPHERE AND IONOSPHERE: INTEGRATED DYNAMICS IN EARTH’S ATMOSPHERE (IDEA)

NASA Astrophysics Data System (ADS)

Akmaev, R. A.; Fuller-Rowell, T. J.; Wu, F.; Wang, H.; Juang, H.; Moorthi, S.; Iredell, M.

2009-12-01

The upper atmosphere and ionosphere exhibit variability and phenomena that have been associated with planetary and tidal waves originating in the lower atmosphere. To study and be able to predict the effects of these global-scale dynamical perturbations on the coupled thermosphere-ionosphere-electrodynamics system a new coupled model is being developed under the IDEA project. To efficiently cross the infamous R2O “death valley”, from the outset the IDEA project leverages the natural synergy between NOAA’s National Weather Service’s (NWS) Space Weather Prediction and Environmental Modeling Centers and a NOAA-University of Colorado cooperative institute (CIRES). IDEA interactively couples a Whole Atmosphere Model (WAM) with ionosphere-plasmasphere and electrodynamics models. WAM is a 150-layer general circulation model (GCM) based on NWS’s operational weather prediction Global Forecast System (GFS) extended from its nominal top altitude of 62 km to over 600 km. It incorporates relevant physical processes including those responsible for the generation of tidal and planetary waves in the troposphere and stratosphere. Long-term simulations reveal realistic seasonal variability of tidal waves with a substantial contribution from non-migrating tidal modes, recently implicated in the observed morphology of the ionosphere. Such phenomena as the thermospheric Midnight Temperature Maximum (MTM), previously associated with the tides, are also realistically simulated for the first time.

Contributions of atmospheric nitrogen deposition to U.S. estuaries: Summary and conclusions: Chapter 8

USGS Publications Warehouse

Stacey, Paul E.; Greening, Holly; Kremer, James N.; Peterson, David; Tomasko, David A.; Valigura, Richard A.; Alexander, Richard B.; Castro, Mark S.; Meyers, Tilden P.; Paerl, Hans W.; Stacey, Paul E.; Turner, R. Eugene

2001-01-01

A NOAA project was initiated in 1998, with support from the U.S. EPA, to develop state-of-the-art estimates of atmospheric N deposition to estuarine watersheds and water surfaces and its delivery to the estuaries. Work groups were formed to address N deposition rates, indirect (from the watershed) yields from atmospheric and other anthropogenic sources, and direct deposition on the estuarine waterbodies, and to evaluate the levels of uncertainty within the estimates. Watershed N yields were estimated using both a land-use based process approach and a national (SPARROW) model, compared to each other, and compared to estimates of N yield from the literature. The total N yields predicted by the national model were similar to values found in the literature and the land-use derived estimates were consistently higher. Atmospheric N yield estimates were within a similar range for the two approaches, but tended to be higher in the land-use based estimates and were not wellcorrelated. Median atmospheric N yields were around 15% of the total N yield for both groups, but ranged as high as 60% when both direct and indirect deposition were considered. Although not the dominant source of anthropogenic N, atmospheric N is, and will undoubtedly continue to be, an important factor in culturally eutrophied estuarine systems, warranting additional research and management attention.

Atmospheric deposition of selected chemicals and their effect on nonpoint-source pollution in the Twin Cities Metropolitan Area, Minnesota

USGS Publications Warehouse

Brown, R.G.

1984-01-01

The atmospheric contribution to nonpoint-source-runoff pollution of nitrogen, in the form of nitrite-plus-nitrate, and lead was extremely high contributing as much as 84 percent of the runoff load. In contrast, phosphorus and chloride inputs were low averaging of 6 percent of the total runoff load. Future investigations of nonpoint-source pollution in runoff might include collection of data on atmospheric deposition of nitrite-plus-nitrate nitrogen and lead because of the importance of that source of these constituents in runoff.

Atmospheric nitrate export in streams along a montane to urban gradient.

PubMed

Bourgeois, Ilann; Savarino, Joel; Némery, Julien; Caillon, Nicolas; Albertin, Sarah; Delbart, Franck; Voisin, Didier; Clément, Jean-Christophe

2018-08-15

Nitrogen (N) emissions associated with urbanization exacerbate the atmospheric N influx to remote ecosystems - like mountains -, leading to well-documented detrimental effects on ecosystems (e.g., soil acidification, pollution of freshwaters). Here, the importance and fate of N deposition in a watershed was evaluated along a montane to urban gradient, using a multi-isotopic tracers approach (Δ 17 O, δ 15 N, δ 18 O of nitrate, δ 2 H and δ 18 O of water). In this setting, the montane streams had higher proportions of atmospheric nitrate compared to urban streams, and exported more atmospheric nitrate on a yearly basis (0.35 vs 0.10 kg-Nha -1 yr -1 ). In urban areas, nitrate exports were driven by groundwater, whereas in the catchment head nitrate exports were dominated by surface runoff. The main sources of nitrate to the montane streams were microbial nitrification and atmospheric deposition, whereas microbial nitrification and sewage leakage contributed most to urban streams. Based on the measurement of δ 15 N and δ 18 O-NO 3 - , biological processes such as denitrification or N assimilation were not predominant in any streams in this study. The observed low δ 15 N and δ 18 O range of terrestrial nitrate (i.e., nitrate not coming from atmospheric deposition) in surface water compared to literature suggests that atmospheric deposition may be underestimated as a direct source of N. Copyright © 2018 Elsevier B.V. All rights reserved.

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, Warren

2014-07-03

As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 inmore » the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.« less

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S., Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beverly E. Law

2011-10-05

As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 inmore » the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.« less

Bioavailable mercury cycling in polar snowpacks.

PubMed

Larose, Catherine; Dommergue, Aurélien; Marusczak, Nicolas; Coves, Jacques; Ferrari, Christophe P; Schneider, Dominique

2011-03-15

Polar regions are subject to contamination by mercury (Hg) transported from lower latitudes, severely impacting human and animal health. Atmospheric Mercury Depletion Events (AMDEs) are an episodic process by which Hg is transferred from the atmospheric reservoir to arctic snowpacks. The fate of Hg deposited during these events is the subject of numerous studies, but its speciation remains unclear, especially in terms of environmentally relevant forms such as bioavailable mercury (BioHg). Here, using a bacterial mer-lux biosensor, we report the fraction of newly deposited Hg at the surface and at the bottom of the snowpack that is bioavailable. Snow samples were collected over a two-month arctic field campaign in 2008. In surface snow, BioHg is related to atmospheric Hg deposition and snow fall events were shown to contribute to higher proportions of BioHg than AMDEs. Based on our data, AMDEs represent a potential source of 20 t.y(-1) of BioHg, while wet and dry deposition pathways may provide 135-225 t.y(-1) of BioHg to Arctic surfaces.

Rainforest-initiated wet season onset over the southern Amazon.

PubMed

Wright, Jonathon S; Fu, Rong; Worden, John R; Chakraborty, Sudip; Clinton, Nicholas E; Risi, Camille; Sun, Ying; Yin, Lei

2017-08-08

Although it is well established that transpiration contributes much of the water for rainfall over Amazonia, it remains unclear whether transpiration helps to drive or merely responds to the seasonal cycle of rainfall. Here, we use multiple independent satellite datasets to show that rainforest transpiration enables an increase of shallow convection that moistens and destabilizes the atmosphere during the initial stages of the dry-to-wet season transition. This shallow convection moisture pump (SCMP) preconditions the atmosphere at the regional scale for a rapid increase in rain-bearing deep convection, which in turn drives moisture convergence and wet season onset 2-3 mo before the arrival of the Intertropical Convergence Zone (ITCZ). Aerosols produced by late dry season biomass burning may alter the efficiency of the SCMP. Our results highlight the mechanisms by which interactions among land surface processes, atmospheric convection, and biomass burning may alter the timing of wet season onset and provide a mechanistic framework for understanding how deforestation extends the dry season and enhances regional vulnerability to drought.

Rainforest-initiated wet season onset over the southern Amazon

PubMed Central

Wright, Jonathon S.; Fu, Rong; Worden, John R.; Chakraborty, Sudip; Clinton, Nicholas E.; Risi, Camille; Sun, Ying; Yin, Lei

2017-01-01

Although it is well established that transpiration contributes much of the water for rainfall over Amazonia, it remains unclear whether transpiration helps to drive or merely responds to the seasonal cycle of rainfall. Here, we use multiple independent satellite datasets to show that rainforest transpiration enables an increase of shallow convection that moistens and destabilizes the atmosphere during the initial stages of the dry-to-wet season transition. This shallow convection moisture pump (SCMP) preconditions the atmosphere at the regional scale for a rapid increase in rain-bearing deep convection, which in turn drives moisture convergence and wet season onset 2–3 mo before the arrival of the Intertropical Convergence Zone (ITCZ). Aerosols produced by late dry season biomass burning may alter the efficiency of the SCMP. Our results highlight the mechanisms by which interactions among land surface processes, atmospheric convection, and biomass burning may alter the timing of wet season onset and provide a mechanistic framework for understanding how deforestation extends the dry season and enhances regional vulnerability to drought. PMID:28729375

Atmospheric redistribution of reactive nitrogen and phosphorus by wildfires and implications for global carbon cycling

NASA Astrophysics Data System (ADS)

Randerson, J. T.; Xu, L.; Wiggins, E. B.; Chen, Y.; Riley, W. J.; Mekonnen, Z. A.; Pellegrini, A.; Mahowald, N. M.

2017-12-01

Fires are an important process regulating the redistribution of nutrients within terrestrial ecosystems. Frequently burning ecosystems such as savannas are a net source of N and P to the atmosphere each year, with atmospheric transport and dry and wet deposition increasing nutrient availability in downwind ecosystems and over the open ocean. Transport of N and P aerosols from savanna fires within the Hadley circulation contributes to nutrient deposition over tropical forests, yielding an important cross-biome nutrient transfer. Pyrodenitrification of reactive N increases with fire temperature and modified combustion efficiency, generating a global net biospheric loss of approximately 14 Tg N per year. Here we analyze atmospheric N and P redistribution using the Global Fire Emissions Database version 4s and the Accelerated Climate Modeling for Energy earth system model. We synthesize literature estimates of N and P concentrations in fire-emitted aerosols and ecosystem mass balance measurements to help constrain model estimates of these biosphere-atmosphere fluxes. In our analysis, we estimate the fraction of terrestrial net primary production (NPP) that is sustained by fire-emitted P and reactive N from upwind ecosystems. We then evaluate how recent global declines in burned area in savanna and grassland ecosystems may be changing nutrient availability in downwind ecosystems.

Glacial seismology.

PubMed

Aster, R C; Winberry, J P

2017-12-01

Seismic source and wave propagation studies contribute to understanding structure, transport, fracture mechanics, mass balance, and other processes within glaciers and surrounding environments. Glaciogenic seismic waves readily couple with the bulk Earth, and can be recorded by seismographs deployed at local to global ranges. Although the fracturing, ablating, melting, and/or highly irregular environment of active glaciers can be highly unstable and hazardous, informative seismic measurements can commonly be made at stable proximal ice or rock sites. Seismology also contributes more broadly to emerging studies of elastic and gravity wave coupling between the atmosphere, oceans, solid Earth, and cryosphere, and recent scientific and technical advances have produced glaciological/seismological collaborations across a broad range of scales and processes. This importantly includes improved insight into the responses of cryospheric systems to changing climate and other environmental conditions. Here, we review relevant fundamental physics and glaciology, and provide a broad review of the current state of glacial seismology and its rapidly evolving future directions.

Cometary material and the origins of life on earth

NASA Technical Reports Server (NTRS)

Lazcano-Araujo, A.; Oro, J.

1981-01-01

The role of cometary material in determining the environmental conditions of the prebiotic earth is reviewed. The organic synthesis pathways that occur in dense interstellar clouds and in comets are examined, and complex organic molecules believed to exist (amino acids, carboxylic acids, purines, pyrimidines and hydrocarbons) based on spectral detections of degradation products are noted. Estimates of the amount of terrestrial volatiles of cometary origin that may have been acquired in collisions during the early history of the earth are considered, and shown to dominate any estimated contributions to terrestrial carbon from other extraterrestrial sources. Current evidence that the origin and early evolution of life began about four billion years ago is discussed in relation to the cometary bombardment processes occurring at the time and the resultant shock waves, reducing atmospheres and reactive chemical species. It is thus concluded that comets contributed significantly to the processes of chemical evolution necessary for the emergence of life on earth.

Glacial seismology

NASA Astrophysics Data System (ADS)

Aster, R. C.; Winberry, J. P.

2017-12-01

Seismic source and wave propagation studies contribute to understanding structure, transport, fracture mechanics, mass balance, and other processes within glaciers and surrounding environments. Glaciogenic seismic waves readily couple with the bulk Earth, and can be recorded by seismographs deployed at local to global ranges. Although the fracturing, ablating, melting, and/or highly irregular environment of active glaciers can be highly unstable and hazardous, informative seismic measurements can commonly be made at stable proximal ice or rock sites. Seismology also contributes more broadly to emerging studies of elastic and gravity wave coupling between the atmosphere, oceans, solid Earth, and cryosphere, and recent scientific and technical advances have produced glaciological/seismological collaborations across a broad range of scales and processes. This importantly includes improved insight into the responses of cryospheric systems to changing climate and other environmental conditions. Here, we review relevant fundamental physics and glaciology, and provide a broad review of the current state of glacial seismology and its rapidly evolving future directions.

The Role of Heterotrophic Microbial Communities in Estuarine C Budgets and the Biogeochemical C Cycle with Implications for Global Warming: Research Opportunities and Challenges.

PubMed

Anderson, O Roger

2016-05-01

Estuaries are among the most productive and economically important marine ecosystems at the land-ocean interface and contribute significantly to exchange of CO2 with the atmosphere. Estuarine microbial communities are major links in the biogeochemical C cycle and flow of C in food webs from primary producers to higher consumers. Considerable attention has been given to bacteria and autotrophic eukaryotes in estuarine ecosystems, but less research has been devoted to the role of heterotrophic eukaryotic microbes. Current research is reviewed here on the role of heterotrophic eukaryotic microbes in C biogeochemistry and ecology of estuaries, with particular attention to C budgets, trophodynamics, and the metabolic fate of C in microbial communities. Some attention is given to the importance of these processes in climate change and global warming, especially in relation to sources and sinks of atmospheric CO2 , while also documenting the current paucity of research on the role of eukaryotic microbes that contribute to this larger question of C biogeochemistry and the environment. Some recommendations are made for future directions of research and opportunities of applying newer technologies and analytical approaches to a more refined analysis of the role of C in estuarine microbial community processes and the biogeochemical C cycle. © 2015 The Author Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.

Temperature Dependency of the Correlation between Secondary Organic Aerosol and Monoterpenes Concentrations at a Boreal Forest Site in Finland

NASA Astrophysics Data System (ADS)

Zhou, Y.; Zhang, W.; Rinne, J.

2016-12-01

Climate feedbacks represent the large uncertainty in the climate projection partly due to the difficulties to quantify the feedback mechanisms in the biosphere-atmosphere interaction. Recently, a negative climate feedback mechanism whereby higher temperatures and CO2-levels boost continental biomass production, leading to increased biogenic secondary organic aerosol (SOA) and cloud condensation nuclei concentrations, tending to cause cooling, has been attached much attention. To quantify the relationship between biogenic organic compounds (BVOCs) and SOA, a five-year data set (2008, 2010-2011,2013-2014) for SOA and monoterpenes concentrations (the dominant fraction of BVOCs) measured at the SMEAR II station in Hyytiälä, Finland, is analyzed. Our results show that there is a moderate linear correlation between SOA and monoterpenes concentration with the correlation coefficient (R) as 0.66. To rule out the influence of anthropogenic aerosols, the dataset is further filtered by selecting the data at the wind direction of cleaner air mass, leading to an improved R as 0.68. As temperature is a critical factor for vegetation growth, BVOC emissions, and condensation rate, the correlation between SOA and monoterpenes concentration at different temperature windows are studied. The result shows a higher R and slope of linear regression as temperature increases. To identify the dominant oxidant responsible for the BVOC-SOA conversion, the correlations between SOA concentration and the monoterpenes oxidation rates by O3 and OH are compared, suggesting more SOA is contributed by O3 oxidation process. Finally, the possible processes and factors such as the atmospheric boundary layer depth, limiting factor in the monoterpenes oxidation process, as well as temperature sensitivity in the condensation process contributing to the temperature dependence of correlation between BVOA and SOA are investigated.

Cosmic ray interactions with lunar materials - Nature and composition of species formed

NASA Technical Reports Server (NTRS)

Mukherjee, N. R.

1976-01-01

The paper discusses the effect of cosmic-ray proton interactions with lunar material, the nature and composition of the species resulting from these interactions, and the contribution of these species to the lunar atmosphere. It is shown that hydrogen atoms resulting from cosmic-ray proton neutralization escape into the atmosphere mostly as H2, that only a small fraction of the very small amount of OH and H2O produced by cosmic-ray protons escapes into the atmosphere, and that cosmic-ray protons play a very minor role, as compared with solar-wind protons, in producing lunar atmospheric hydrogen and hydrogenated species. It is concluded that the atmospheric contributions of H2, H, OH, and H2O produced by cosmic-ray protons are about three orders of magnitude less than those due to solar-wind protons.

Reactive nitrogen deposition to South East Asian rainforest

NASA Astrophysics Data System (ADS)

di Marco, Chiara F.; Phillips, Gavin J.; Thomas, Rick; Tang, Sim; Nemitz, Eiko; Sutton, Mark A.; Fowler, David; Lim, Sei F.

2010-05-01

The supply of reactive nitrogen (N) to global terrestrial ecosystems has doubled since the 1960s as a consequence of human activities, such as fertilizer application and production of nitrogen oxides by fossil-fuel burning. The deposition of atmospheric N species constitutes a major nutrient input to the biosphere. Tropical forests have been undergoing a radical land use change by increasing cultivation of sugar cane and oil palms and the remaining forests are increasingly affected by anthropogenic activities. Yet, quantifications of atmospheric nitrogen deposition to tropical forests, and nitrogen cycling under near-pristine and polluted conditions are rare. The OP3 project ("Oxidant and Particle Photochemical Processes above a Southeast Asian Tropical Rainforest") was conceived to study how emissions of reactive trace gases from a tropical rain forest mediate the regional scale production and processing of oxidants and particles, and to better understand the impact of these processes on local, regional and global scale atmospheric composition, chemistry and climate. As part of this study we have measured reactive, nitrogen containing trace gas (ammonia, nitric acid) and the associated aerosol components (ammonium, nitrate) at monthly time resolution using a simple filter / denuder for 16 months. These measurements were made at the Bukit Atur Global Atmospheric Watch tower near Danum Valley in the Malaysian state of Sabah, Borneo. In addition, the same compounds were measured at hourly time-resolution during an intensive measurement period, with a combination of a wet-chemistry system based on denuders and steam jet aerosol collectors and an aerosol mass spectrometer (HR-ToF-AMS), providing additional information on the temporal controls. During this period, concentrations and fluxes of NO, NO2 and N2O were also measured. The measurements are used for inferential dry deposition modelling and combined with wet deposition data from the South East Asian Acid Deposition Network to estimate the total annual atmospheric reactive nitrogen deposition to this tropical forest ecosystem and to quantify the relative contribution of the different chemical compounds.

A dynamical perspective on the energetic particles precipitation-middle atmosphere interaction

NASA Astrophysics Data System (ADS)

Karami, Khalil; Sinnhuber, Miriam; Versick, Stefan; Braesicke, Peter

2015-04-01

Energetic particles including protons, electrons and heavier ions, enter the Earth's atmosphere over polar region of both hemispheres, where the geomagnetic lines are considered to be open and connected to the interplanetary medium. This condition allows direct access for energetic particles of solar or galactic origin to directly deposit their own energy into the middle and upper atmosphere. Such particle precipitations can greatly disturb the chemical composition of the upper and middle atmosphere. At polar latitudes, these particles have the potential to penetrate from thermosphere deep into the mesosphere and in rare occasions into the stratosphere. The most important are changes to the budget of atmospheric nitric oxides, NOy, and to atmospheric reactive hydrogen oxides, HOx, which both contribute to ozone loss in the stratosphere and mesosphere. The chemistry-climate general circulation model ECHAM5/MESSy is used to investigate the impact of changed ozone concentration due to energetic particles precipitation on temperatures and wind fields. The simulated anomalies of both zonal mean temperature and zonal wind suggest that these changes are very unlikely to be caused in situ by ozone depletion and indirect dynamical condition is important. The results of our simulations suggests that ozone perturbation is a starting point for a chain of processes resulting in temperature and circulation changes in many areas of the atmosphere. Different dynamical analysis (e.g., frequency of sudden stratospheric warming, dates of stratospheric final warming, divergence of Eliassen-Palm flux and refractive index of planetary waves) are performed to investigate the impact of ozone anomaly originated from high energetic particle precipitation on middle atmospheric temperature and circulation.

Boreal mire Green House Gas exchange in response to global change perturbations

NASA Astrophysics Data System (ADS)

Nilsson, Mats

2017-04-01

High latitude boreal peatlands contribute importantly to the land-atmosphere-hydrosphere exchange of carbon and GHG, i.e. carbon dioxide, methane and dissolved organic carbon. High latitude biomes are identified as most vulnerable to changing climate. High latitudes are also characterized by a strong seasonality in incoming solar radiation, weather conditions and thus also in biogeochemical processes. The strong seasonality in incoming solar radiation, not to change in response to a changing climate, constitute firm constraints on how changes in air temperature, evapotranspiration and precipitation will affect biogeochemical processes underlying the land atmosphere and land hydrosphere exchange of green house gases. In this presentation I combine data from long-term monitoring, long-term field manipulations and detailed chemical analysis to understand how changes in atmosphere and weather conditions influence the major carbon fluxes of a boreal mire Net Ecosystem Carbon Balance. The long-term monitoring data contains >12 years of continuous Eddy Covariance CO2 data, growing season chamber CH4 data and continuous measurements of discharge export of DOC, CO2 and CH4. Data from long-term field snow removal manipulations and growing season temperature increase manipulations are used to further understand the impact of climate on mire carbon and GHG fluxes. Finally we uses Nuclear Magnetic Spectroscopy (NMR) to reveal how century scale changes in atmospheric CO2 from 300 to 400 pm CO2 and temperature have influenced the net photosynthetic capacity of Sphagnum mosses, the single most important plant genus for boreal mire carbon sequestration.

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO2, H2O and dimethyl sulfide

NASA Astrophysics Data System (ADS)

Newland, M. J.; Rickard, A. R.; Vereecken, L.; Muñoz, A.; Ródenas, M.; Bloss, W. J.

2015-08-01

Isoprene is the dominant global biogenic volatile organic compound (VOC) emission. Reactions of isoprene with ozone are known to form stabilised Criegee intermediates (SCIs), which have recently been shown to be potentially important oxidants for SO2 and NO2 in the atmosphere; however the significance of this chemistry for SO2 processing (affecting sulfate aerosol) and NO2 processing (affecting NOx levels) depends critically upon the fate of the SCIs with respect to reaction with water and decomposition. Here, we have investigated the removal of SO2 in the presence of isoprene and ozone, as a function of humidity, under atmospheric boundary layer conditions. The SO2 removal displays a clear dependence on relative humidity, confirming a significant reaction for isoprene-derived SCIs with H2O. Under excess SO2 conditions, the total isoprene ozonolysis SCI yield was calculated to be 0.56 (±0.03). The observed SO2 removal kinetics are consistent with a relative rate constant, k(SCI + H2O) / k(SCI + SO2), of 3.1 (±0.5) × 10-5 for isoprene-derived SCIs. The relative rate constant for k(SCI decomposition) / k(SCI+SO2) is 3.0 (±3.2) × 1011 cm-3. Uncertainties are ±2σ and represent combined systematic and precision components. These kinetic parameters are based on the simplification that a single SCI species is formed in isoprene ozonolysis, an approximation which describes the results well across the full range of experimental conditions. Our data indicate that isoprene-derived SCIs are unlikely to make a substantial contribution to gas-phase SO2 oxidation in the troposphere. We also present results from an analogous set of experiments, which show a clear dependence of SO2 removal in the isoprene-ozone system as a function of dimethyl sulfide concentration. We propose that this behaviour arises from a rapid reaction between isoprene-derived SCIs and dimethyl sulfide (DMS); the observed SO2 removal kinetics are consistent with a relative rate constant, k(SCI + DMS) / k(SCI + SO2), of 3.5 (±1.8). This result suggests that SCIs may contribute to the oxidation of DMS in the atmosphere and that this process could therefore influence new particle formation in regions impacted by emissions of unsaturated hydrocarbons and DMS.

Interactions between bacterial carbon monoxide and hydrogen consumption and plant development on recent volcanic deposits.

PubMed

King, Gary M; Weber, Carolyn F

2008-02-01

Patterns of microbial colonization and interactions between microbial processes and vascular plants on volcanic deposits have received little attention. Previous reports have shown that atmospheric CO and hydrogen contribute significantly to microbial metabolism on Kilauea volcano (Hawaii) deposits with varied ages and successional development. Relationships between CO oxidation and plant communities were not clear, however, since deposit age and vegetation status covaried. To determine plant-microbe interactions in deposits of uniform ages, CO and hydrogen dynamics have been assayed for unvegetated tephra on a 1959 deposit at Pu'u Puai (PP-bare), at the edge of tree 'islands' within the PP deposit (PP-edge) and within PP tree islands (PP-canopy). Similar assays have been conducted for vegetated and unvegetated sites on a 1969 Mauna Ulu (MU) lava flow. Net in situ atmospheric CO uptake was highest at PP-edge and PP-bare sites (2.2+/-0.5 and 1.3+/-0.1 mg CO m(-2) day(-1), respectively), and least for PP-canopy (-3.2+/-0.9 mg CO m(-2) day(-1), net emission). Respiration rates, microbial biomass and maximum CO uptake potential showed an opposing pattern. Comparisons of atmospheric CO uptake and CO(2) production rates indicate that CO contributes significantly to microbial metabolism in PP-bare and MU-unvegetated sites, but negligibly where vegetation is well developed. Nonetheless, maximum potential CO uptake rates indicate that CO oxidizer populations increase with increasing plant biomass and consume CO actively. Some of these CO oxidizers may contribute to elevated nitrogen fixation rates (acetylene reduction) measured within tree islands, and thus, support plant successional development.

Assessment of terrestrial water contributions to polar motion from GRACE and hydrological models

NASA Astrophysics Data System (ADS)

Jin, S. G.; Hassan, A. A.; Feng, G. P.

2012-12-01

The hydrological contribution to polar motion is a major challenge in explaining the observed geodetic residual of non-atmospheric and non-oceanic excitations since hydrological models have limited input of comprehensive global direct observations. Although global terrestrial water storage (TWS) estimated from the Gravity Recovery and Climate Experiment (GRACE) provides a new opportunity to study the hydrological excitation of polar motion, the GRACE gridded data are subject to the post-processing de-striping algorithm, spatial gridded mapping and filter smoothing effects as well as aliasing errors. In this paper, the hydrological contributions to polar motion are investigated and evaluated at seasonal and intra-seasonal time scales using the recovered degree-2 harmonic coefficients from all GRACE spherical harmonic coefficients and hydrological models data with the same filter smoothing and recovering methods, including the Global Land Data Assimilation Systems (GLDAS) model, Climate Prediction Center (CPC) model, the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis products and European Center for Medium-Range Weather Forecasts (ECMWF) operational model (opECMWF). It is shown that GRACE is better in explaining the geodetic residual of non-atmospheric and non-oceanic polar motion excitations at the annual period, while the models give worse estimates with a larger phase shift or amplitude bias. At the semi-annual period, the GRACE estimates are also generally closer to the geodetic residual, but with some biases in phase or amplitude due mainly to some aliasing errors at near semi-annual period from geophysical models. For periods less than 1-year, the hydrological models and GRACE are generally worse in explaining the intraseasonal polar motion excitations.

Host Star Evolution for Planet Habitability.

PubMed

Gallet, Florian; Charbonnel, Corinne; Amard, Louis

2016-11-01

With about 2000 exoplanets discovered within a large range of different configurations of distance from the star, size, mass, and atmospheric conditions, the concept of habitability cannot rely only on the stellar effective temperature anymore. In addition to the natural evolution of habitability with the intrinsic stellar parameters, tidal, magnetic, and atmospheric interactions are believed to have strong impact on the relative position of the planets inside the so-called habitable zone. Moreover, the notion of habitability itself strongly depends on the definition we give to the term "habitable". The aim of this contribution is to provide a global and up-to-date overview of the work done during the last few years about the description and the modelling of the habitability, and to present the physical processes currently includes in this description.

Atmosphere Revitalization Technology Development for Crewed Space Exploration

NASA Technical Reports Server (NTRS)

Perry, Jay L.; Carrasquillo, Robyn L.; Harris, Danny W.

2006-01-01

As space exploration objectives extend human presence beyond low Earth orbit, the solutions to technological challenges presented by supporting human life in the hostile space environment must build upon experience gained during past and present crewed space exploration programs. These programs and the cabin atmosphere revitalization process technologies and systems developed for them represent the National Aeronautics and Space Administration s (NASA) past and present operational knowledge base for maintaining a safe, comfortable environment for the crew. The contributions of these programs to the NASA s technological and operational working knowledge base as well as key strengths and weaknesses to be overcome are discussed. Areas for technological development to address challenges inherent with the Vision for Space Exploration (VSE) are presented and a plan for their development employing unit operations principles is summarized

Terrestrial Carbon Sequestration with Biochar: A Preliminary Assessment of its Global Potential

NASA Astrophysics Data System (ADS)

Amonette, J.; Lehmann, J.; Joseph, S.

2007-12-01

Biochar technology involves the capture of CO2 from the atmosphere by photosynthesis and its ultimate conversion to biochar by pyrolysis. Energy is obtained during the pyrolysis process and the charcoal, or biochar, which is considerably more stable than biomass, may then be incorporated into agricultural lands where it serves to increase the nutrient- and water-holding capacity of soil. With an estimated half-life in soil on the order of centuries to millenia, biochar offers a way of safely storing C for long periods of time while enhancing the productivity of terrestrial ecosystems. Moreover, biochar technology, like other biomass conversion approaches that include C sequestration options, offers a way to decrease the levels of CO2 in the atmosphere. That is, biochar technology is one of the few inherently "carbon-negative" sources of energy. These positive attributes are of little consequence, however, if the total contribution to sequestration is small compared to the need. In this paper, we provide a preliminary assessment of the potential contribution of biochar technology to the mitigation of climate change, and identify some research needs. Currently, the atmospheric C levels are increasing by about 4.1 Gt/yr, with 7.2 Gt/yr being put into the atmosphere by fossil fuel combustion and cement production, and 3.1 Gt/yr being removed from the atmosphere by the ocean (2.2 Gt/yr) and terrestrial processes (0.9 Gt/yr). The uptake by terrestrial processes can be increased significantly by management of the 60.6 Gt/yr of biomass C that is fixed by photosynthesis (i.e., net primary productivity), of which 59 Gt/yr is decomposed and 1.6 Gt/yr combusted. Biomass pyrolysis converts about 50% of the biomass C to char. Of the other 50% that is converted to bio-oil and bio-gas, the net energy production is about 62% efficient. Thus, pyrolysis of 1 Gt of biomass C would provide energy equivalent to about 0.3 Gt of fossil C and could be used to offset that amount of fossil C, while sequestering 0.5 Gt as biochar. Of the 60.6 Gt/yr of biomass that is fixed in usable form, we estimate that perhaps 10% of it (6.1 Gt/yr) could become available in one form or another (crop and forestry residues, and animal waste) for pyrolysis. This level of pyrolysis would offset 1.8 Gt/yr of fossil C, and sequester 3.0 Gt/yr as biochar, enough to halt the increase and actually decrease the level of atmospheric C by 0.7 Gt/yr. Even at half this level (i.e., 5% of annually fixed biomass), pyrolysis would be sufficient to decrease the global C cycle imbalance by 2.4 Gt/yr and in combination with other sequestration options help to achieve the minimum goal of C neutrality. Clearly, the potential contribution of biochar technology is large, perhaps large enough to mitigate climate change alone. However, this preliminary assessment is tempered by several unknowns. Research is needed to further define the impacts of biochar amendments on soil biota, productivity, and greenhouse gas production. For example, there is some evidence that N2O and CH4 production is decreased by biochar amendments, but the mechanisms responsible are unknown. The impact of different types of biochar and pyrolysis conditions also needs to be determined. Lastly, total accounting for greenhouse gas emissions coupled with economic analyses to determine the economic potential of the technology under various scenarios is essential.

Atmospheric aerosol source identification and estimates of source contributions to air pollution in Dundee, UK

NASA Astrophysics Data System (ADS)

Qin, Y.; Oduyemi, K.

Anthropogenic aerosol (PM 10) emission sources sampled at an air quality monitoring station in Dundee have been analysed. However, the information on local natural aerosol emission sources was unavailable. A method that combines receptor model and atmospheric dispersion model was used to identify aerosol sources and estimate source contributions to air pollution. The receptor model identified five sources. These are aged marine aerosol source with some chlorine replaced by sulphate, secondary aerosol source of ammonium sulphate, secondary aerosol source of ammonium nitrate, soil and construction dust source, and incinerator and fuel oil burning emission source. For the vehicle emission source, which has been comprehensively described in the atmospheric emission inventory but cannot be identified by the receptor model, an atmospheric dispersion model was used to estimate its contributions. In Dundee, a significant percentage, 67.5%, of the aerosol mass sampled at the study station could be attributed to the six sources named above.

Tidal atmospheric and ocean loading in VLBI analysis

NASA Astrophysics Data System (ADS)

Girdiuk, Anastasiia; Schindelegger, Michael; Böhm, Johannes

2016-04-01

In VLBI (Very Long Baseline Interferometry) analysis, reductions for tidal atmospheric and ocean loading are commonly used according to the IERS Conventions. In this presentation we examine such loading corrections from contemporary geophysical models within routine VLBI processing and discuss the internal consistency of the applied corrections for various effects. In detail, two gravitational ocean tide models, FES2004 and the recent FES2012 atlas with a much finer horizontal resolution and an improved description of hydrodynamic processes, are employed. Moreover, the contribution of atmospheric tidal loading is also re-considered based on data taken from two providers of station displacements, Goddard Space Flight Center and the TU Wien group. Those two models differ in terms of the underlying meteorological data, which can be a reason for inconsistency of VLBI reductions and may lead to systematics in the VLBI products at tidal frequencies. We validate this assumption in terms of Earth rotation parameters, by a tidal analysis of diurnal and semi-diurnal universal time and semi-diurnal polar motion variations as determined with the Vienna VLBI Software. Applying the loading models in a consistent way still leads to unexplained residuals at about 4-5 μas in the diurnal polar motion band, thus limiting the possibility of assessing geophysical models at this particular frequency.

Turbulent transport of large particles in the atmospheric boundary layer

NASA Astrophysics Data System (ADS)

Richter, D. H.; Chamecki, M.

2017-12-01

To describe the transport of heavy dust particles in the atmosphere, assumptions must typically be made in order to connect the micro-scale emission processes with the larger-scale atmospheric motions. In the context of numerical models, this can be thought of as the transport process which occurs between the domain bottom and the first vertical grid point. For example, in the limit of small particles (both low inertia and low settling velocity), theory built upon Monin-Obukhov similarity has proven effective in relating mean dust concentration profiles to surface emission fluxes. For increasing particle mass, however, it becomes more difficult to represent dust transport as a simple extension of the transport of a passive scalar due to issues such as the crossing trajectories effect. This study focuses specifically on the problem of large particle transport and dispersion in the turbulent boundary layer by utilizing direct numerical simulations with Lagrangian point-particle tracking to determine under what, if any, conditions the large dust particles (larger than 10 micron in diameter) can be accurately described in a simplified Eulerian framework. In particular, results will be presented detailing the independent contributions of both particle inertia and particle settling velocity relative to the strength of the surrounding turbulent flow, and consequences of overestimating surface fluxes via traditional parameterizations will be demonstrated.

Degradation of pentachlorophenol in soil by pulsed corona discharge plasma.

PubMed

Wang, Tie Cheng; Lu, Na; Li, Jie; Wu, Yan

2010-08-15

The remediation of pentachlorophenol (PCP) contaminated soil using pulsed corona discharge plasma was reported in this study. The effect of practical run parameters such as peak pulse voltage, pulse frequency, gas atmospheres (air, O(2), Ar and N(2)), air flow rate and pollution time on PCP degradation was investigated, and the intermediate products were also studied. The results indicated that PCP degradation efficiency increased with an increase in peak pulse voltage or pulse frequency, due to the enhancement of energy input. There existed a maximal PCP degradation efficiency with the change of air flow rate. PCP degradation efficiencies under oxygen and air atmospheres were achieved 92% and 77% after 45 min of discharge treatment at 14.0 kV, respectively, which were only 19% and 8% under argon and nitrogen atmospheres, respectively. O(3) played an important role in PCP degradation. However, other processes also contributed to PCP degradation, such as N, N(2)(+), N(+) and OH. The pollution time evidenced slight influence on PCP degradation. The main intermediate products produced during the treatment process were identified as tetrachlorocatechol, tetrachlorohydroquinone, acetic acid, formic acid and oxalic acid by HPLC/MS and ion chromatography. This study is expected to provide reference for the application of pulsed corona discharge in soil remediation. Copyright 2010 Elsevier B.V. All rights reserved.

Air quality assessment and the use of specific markers to apportion pollutants to source

NASA Astrophysics Data System (ADS)

Douce, David Stewart

The contributions of specific polluting sources to both indoor and outdoor atmospheric pollution are difficult to determine, as solid and gaseous products from different combustion sources are often similar. Sometimes, however, a marker compound can be identified that is unique to a pollution source (or at least not present in most other local combustion sources) and which will allow assessment of the contribution of that source to total atmospheric pollution.The aim of this study was to identify suitable marker compounds and methods for the apportionment (assessment of percentage contribution) of specific sources to atmospheric pollution. The sources selected were diesel exhaust emissions in outdoor, and environmental tobacco smoke (ETS) in indoor environments. Studies with controlled (laboratory) atmospheres would be followed by field studies using these methods and markers to produce apportionments for these sources to air pollution in selected environments. Initial analysis of such polluting sources was therefore the qualitative analysis of volatile compounds and particulate associated material, both organic and inorganic. Volatile organic compounds were adsorbed onto various resins, while particulate material was sampled onto various filter paper types. Organics were determined by GC-AED and GC-MS, and elements by ICP-MS.1-Nitropyrene was identified as a suitable marker for diesel particulate emissions (<5um). A large volume air sample from Sheffield city centre using 1-nitropyrene as a marker suggested that 63% of atmospheric particulate material (<5um) might be of diesel origin. However the concentration of 1-nitropyrene is low in atmospheric samples, and in the volumes used in routine sampling the amount of 1-nitropyrene was below the limit of detection on the instrument used. In an alternative approach the aliphatic alkane tetracosane (C24) was used as a diesel marker for urban air, with a 1-nitropyrene:tetracosane ratio derived from the average results from laboratory experiments with a diesel engine running at various speeds and loads. This approach yielded apportionment values ranging from 5-85% for the diesel contribution to particulate material (<5mum) in the urban air of Sheffield. No volatile marker compound was found for diesel apportionment.The contribution of ETS to atmospheric pollution has previously been estimated from the measurement of respirable suspended particulates (RSP), which was superseded by total UV absorbance and total fluorescence of a methanol extract. More recent work has suggested the use of solanesol or scopoletin as marker compounds. This thesis shows that the non specific methods overestimated the particulate contribution of ETS in some atmospheres, and that solanesol is a better marker compound than scopoletin. Preliminary studies from a small number of smokers homes and offices, with solanesol as a marker compound for particulate ETS, indicated that ETS contributions to total particulate material (<5mum) ranged from 6 to 49% in homes and 11 to 28% in offices.Pyrrole was used as a marker for ETS contribution to volatile organic pollution, and studies with controlled atmospheres with a smoking machine allowed calculation of the ratios of pyrrole to other volatile organic compounds (VOC's) in ETS. Samples from the field study were used to produce apportionment percentage levels of benzene, toluene, o-xylene and p+m-xylene associated with ETS.In addition the use of tree bark as a atmospheric sink for airborne particulates was investigated. Six nitrated polycyclic aromatic hydrocarbons associated with diesel emissions were quantified in bark extracts and levels of these were found to be highest during winter months.

Non-Potential Magnetic Fields and Magnetic Reconnection In Low Collisional Plasmas-Discovery of Solar EUV Mini-Sigmoids and Development of Novel In-Space Propulsion Systems

NASA Astrophysics Data System (ADS)

Chesny, David

Magnetic reconnection is the source of many of the most powerful explosions of astrophysical plasmas in the universe. Blazars, magnetars, stellar atmospheres, and planetary magnetic fields have all been shown to be primary sites of strong reconnection events. For studying the fundamental physics behind this process, the solar atmosphere is our most accessible laboratory setting. Magnetic reconnection resulting from non-potential fields leads to plasma heating and particle acceleration, often in the form of explosive activity, contributing to coronal heating and the solar wind. Large-scale non-potential (sigmoid) fields in the solar atmosphere are poorly understood due to their crowded neighborhoods. For the first time, small-scale, non-potential loop structures have been observed in quiet Sun EUV observations. Fourteen unique mini-sigmoid events and three diffuse non-potential loops have been discovered, suggesting a multi-scaled self-similarity in the sigmoid formation process. These events are on the order of 10 arcseconds in length and do not appear in X-ray emissions, where large-scale sigmoids are well documented. We have discovered the first evidence of sigmoidal structuring in EUV bright point phenomena, which are prolific events in the solar atmosphere. Observations of these mini-sigmoids suggest that they are being formed via tether-cutting reconnection, a process observed to occur at active region scales. Thus, tether-cutting is suggested to be ubiquitous throughout the solar atmosphere. These dynamics are shown to be a function of the free magnetic energy in the quiet Sun network. Recently, the reconnection process has been reproduced in Earth-based laboratory tokamaks. Easily achievable magnetic field configurations can induce reconnection and result in ion acceleration. Here, magnetic reconnection is utilized as the plasma acceleration mechanism for a theoretical propulsion system. The theory of torsional spine reconnection is shown to result in ion velocities of > 3000 km s-1 and thrusts on the order of 3-15 N. As current in-use ion propulsion technology can only achieve ˜ 30 km s-1, the proposed design can substantially increase thrust on a spacecraft and provide for fast manned interplanetary travel.

Observations of ambient monoterpenes at a costal site in the East Mediterranean

NASA Astrophysics Data System (ADS)

Tzitzikalaki, Evaggelia; Kalivitis, Nikolaos; Kouvarakis, Giorgos; Kanakidou, Maria; Mihalopoulos, Nikolaos

2015-04-01

Observations of ambient monoterpenes at a costal site in the East Mediterranean Biogenic Volatile Organic Compounds (BVOCs) affect the oxidizing capacity of the atmosphere since they react with hydroxyl radicals, nitrate radicals and ozone, and participate in ozone formation in the presence of sufficient amounts of nitrogen oxides. Moreover, BVOC oxidation products contribute to new particle formation and growth processes. While isoprene is emitted in the largest amount among BVOCs into the atmosphere, monoterpenes are also important for atmospheric chemistry. Tree species are responsible of the most BVOC emissions to the atmosphere but little is known about the contribution of shrub and long-range transport to the ambient BVOC concentrations. In the Mediterranean region monoterpene measurements are scarce and are limited in temporal and ecosystem coverage (forested areas). The present study presents long- term measurements of monoterpenes at a remote coastal site without tree vegetation under typical phrygana vegetation of Crete island in Greece. Measurements took place (35° 20' N, 25° 40' E, 250m a.s.l) on the north east side of the island of Crete at the Finokalia monitoring station of the University of Crete (http://finokalia.chemistry.uoc.gr). Two intensive campaigns took place, one during spring (13/03-08/04/2014) and one during summer(19/06 - 04/08/2014). During each campaign diurnal cycles were measured collecting 9 samples per day(every two hours). In addition, one diurnal cycle per week has been measured since 13/10/2014. Off-line sampling took place in adsorption tubes, using stainless steel cartridges filled with Tenax TA for one hour at 200 ml/min flow rate. Samples were stored at 40C and analyzed within two days. The samples were after desorption by a Thermal Desorber were analyzed by a GC-FID system. The most abundant monoterpenes were found to be Δ3-carene and limonene.Highest concentrations were observed during autumn when a clear diurnal cycle has been seen with maximum for both Δ3-carene and limonene at late afternoon. During summer, no clear diurnal variance was observed while in spring the cycle was weaker. The results are analyzed together with new particle formation observations at the Finokalia station to estimate possible links of BVOCs to the formation and growth processes of atmospheric particles in the area.

SOA formation from gasoline vehicles: from the tailpipe to the atmosphere

NASA Astrophysics Data System (ADS)

Robinson, A. L.; Zhao, Y.; Lambe, A. T.; Saleh, R.; Saliba, G.; Tkacik, D. S.

2017-12-01

Secondary organic aerosol (SOA) formation from gasoline vehicles has been indicated as an important source of atmospheric SOA, but its contribution to atmospheric SOA is loosely constrained due to the lack of measurements to link SOA formation from the tailpipe to atmospheric SOA. In this study, we determine the contribution of SOA formation based on measurements made with a Potential Aerosol Mass (PAM) oxidation flow reactor by oxidizing vehicular exhaust and ambient air. We first investigate SOA formation from dilute gasoline-vehicle exhaust during chassis dynamometer testing. The test fleet consists of both vehicles equipped with gasoline direct injection engines (GDI vehicles) and those equipped with port fuel injection engines (PFI vehicles). These vehicles span a wide range of emissions standards from Tier0 to Super Ultra-Low Emission Vehicles (SULEV). Then, we combine our measurements of SOA formation from gasoline vehicles during dynamometer testing with measurements of SOA formation using a PAM reactor conducted in a highway tunnel and in the unban atmosphere. Comparisons of SOA formation between these datasets enable us to quantitatively connect SOA formation from individual vehicles, to a large on-road fleet, and to the atmosphere. To facilitate the comparisons, we account for the effects of both the photochemical age and dilution on SOA formation. Our results show that SOA formation from gasoline vehicles can contribute over 50% of fossil fuel-related atmospheric SOA in the Los Angeles area. Furthermore, our results demonstrate that the tightening of emissions standards effectively reduces SOA formation from gasoline vehicles, including both PFI and GDI vehicles, if the atmospheric chemistry regime remains the same.

Characterizing soil moisture and snow cover effects on boreal-arctic soil freeze/thaw dynamics and cold-season carbon emissions

NASA Astrophysics Data System (ADS)

Yi, Y.; Kimball, J. S.; Moghaddam, M.; Chen, R. H.; Reichle, R. H.; Oechel, W. C.; Zona, D.

2017-12-01

The contribution of cold season respiration to boreal-arctic carbon cycle and its potential feedbacks to climate change remain poorly quantified. Here, we developed an integrated modeling framework combining airborne low frequency (L+P-band) airborne radar retrievals and landscape level (≥1km) environmental observations from satellite optical and microwave sensors with a detailed permafrost carbon model to investigate underlying processes controlling soil freeze/thaw (FT) dynamics and cold season carbon emissions. The permafrost carbon model simulates the snow and soil thermal dynamics with soil water phase change included and accounts for soil carbon decomposition up to 3m below surface. Local-scale ( 50m) radar retrievals of active layer thickness (ALT), soil moisture and freeze/thaw (FT) status from NASA airborne UAVSAR and AirMOSS sensors are used to inform the model parameterizations of soil moisture effects on soil FT dynamics, and scaling properties of active layer processes. Both tower observed land-atmosphere fluxes and atmospheric CO2 measurements are used to evaluate the model processes controlling cold season carbon respiration, particularly the effects of snow cover and soil moisture on deep soil carbon emissions during the early cold season. Initial comparisons showed that the model can well capture the seasonality of cold season respiration in both tundra and boreal forest areas, with large emissions in late fall and early winter and gradually diminishing throughout the winter. Model sensitivity analyses are used to clarify how changes in soil thermodynamics at depth control the magnitude and seasonality of cold season respiration, and how a deeper unfrozen active layer with warming may contribute to changes in cold season respiration. Model outputs include ALT and regional carbon fluxes at 1-km resolution spanning recent satellite era (2001-present) across Alaska. These results will be used to quantify cold season respiration contributions to the annual carbon cycle and help close the boreal-arctic annual carbon budget.

Modeling Microbial Processes in EPIC to Estimate Greenhouse Gas Emissions from soils

NASA Astrophysics Data System (ADS)

Schwab, D. E.; Izaurralde, R. C.; McGill, W. B.; Williams, J. R.; Schmid, E.

2009-12-01

Emissions of trace gases (CO2, N2O and CH4) to the atmosphere from managed terrestrial ecosystems have been contributing significantly to the warming of Earth. Trace gas production is dominated by biospheric processes. An improved knowledge of the soil-plant-atmosphere interface is of key importance for understanding trace gas dynamics. In soils, microbial metabolism plays a key role in the release or uptake of trace gases. Here we present work on the biophysical and biogeochemical model EPIC (Environmental Policy/Integrated Climate) to extend its capabilities to simulate CO2 and N2O fluxes in managed and unmanaged ecosystems. Emphasis will be given to recently developed, microbially-based, denitrification and nitrification modules. The soil-atmosphere exchange of trace gases can be measured by using various equipments, but often these measurements exhibit extreme space-time variability. We use hourly time steps to account for the variability induced by small changes in environmental conditions. Soils are often studied as macroscopic systems, although their functions are predominantly controlled at a microscopic level; i.e. the level of the microorganisms. We include these processes to the extent that these are known and can be quantitatively described. We represent soil dynamics mathematically with routines for gas diffusion, Michael Menten processes, electron budgeting and other processes such as uptake and transformations. We hypothesize that maximization of energy capture form scarce substrates using energetic favorable reactions drives evolution and that competitive advantage can result by depriving a competitor from a substrate. This Microbe Model changes concepts of production of N-containing trace gases; it unifies understanding of N oxidation and reduction, predicts production and evolution of trace gases and is consistent with observations of anaerobic ammonium oxidation.

Towards uncertainty estimates in global operational forecasts of trace gases in the Copernicus Atmosphere Monitoring System

NASA Astrophysics Data System (ADS)

Huijnen, V.; Bouarar, I.; Chabrillat, S. H.; Christophe, Y.; Thierno, D.; Karydis, V.; Marecal, V.; Pozzer, A.; Flemming, J.

2017-12-01

Operational atmospheric composition analyses and forecasts such as developed in the Copernicus Atmosphere Monitoring Service (CAMS) rely on modules describing emissions, chemical conversion, transport and removal processing, as well as data assimilation methods. The CAMS forecasts can be used to drive regional air quality models across the world. Critical analyses of uncertainties in any of these processes are continuously needed to advance the quality of such systems on a global scale, ranging from the surface up to the stratosphere. With regard to the atmospheric chemistry to describe the fate of trace gases, the operational system currently relies on a modified version of the CB05 chemistry scheme for the troposphere combined with the Cariolle scheme to describe stratospheric ozone, as integrated in ECMWF's Integrated Forecasting System (IFS). It is further constrained by assimilation of satellite observations of CO, O3 and NO2. As part of CAMS we have recently developed three fully independent schemes to describe the chemical conversion throughout the atmosphere. These parameterizations originate from parent model codes in MOZART, MOCAGE and a combination of TM5/BASCOE. In this contribution we evaluate the correspondence and elemental differences in the performance of the three schemes in an otherwise identical model configuration (excluding data-assimilation) against a large range of in-situ and satellite-based observations of ozone, CO, VOC's and chlorine-containing trace gases for both troposphere and stratosphere. This analysis aims to provide a measure of model uncertainty in the operational system for tracers that are not, or poorly, constrained by data assimilation. It aims also to provide guidance on the directions for further model improvement with regard to the chemical conversion module.

Methane Production and Transport within the Marsh Biome of Biosphere 2

NASA Technical Reports Server (NTRS)

Molnar, Jennifer; Goodridge, Kelven

1997-01-01

In recent decades, the concentration of methane in the earth's atmosphere increased 1-2% annually. It's rate of increases, combined with methane's effectiveness as a greenhouse gas, has led to an intensive research effort to determine the sources and sinks of the gas in the environment. Biosphere 2 offers a unique opportunity to contribute to the effort because it lacks a major photochemical sink present in the Earth's atmosphere. Researchers can therefore concentrate on biological processes involved in methane cycles. Wetlands are a large source of atmospheric methane, due to anoxic conditions in the sediments and the abundance of organic materials. In order to determine if these conditions in Biosphere 2 also promote methane production, this study looked for the fluxes of methane and methods of transport of the gas from from the water and sediments to the atmosphere in the Marsh Biome. Fluxes of methane from the sediments and waters were measured using static chambers, peepers, and leaf bags. Fluxes and vertical profiles of methane in the sediments show that substantial amounts of methane are being produced in the marsh and are being transported into the Biosphere 2 environment.

Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

2006-01-01

The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

ARM Cloud-Aerosol-Precipitation Experiment (ACAPEX) Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leung, L Ruby

The U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility’s ARM Cloud-Aerosol-Precipitation Experiment (ACAPEX) field campaign contributes to CalWater 2015, a multi-agency field campaign that aims to improve understanding of atmospheric rivers and aerosol sources and transport that influence cloud and precipitation processes. The ultimate goal is to reduce uncertainties in weather predictions and climate projections of droughts and floods in California. With the DOE G-1 aircraft and ARM Mobile Facility 2 (AMF2) well equipped for making aerosol and cloud measurements, ACAPEX focuses specifically on understanding how aerosols from local pollution and long-range transport affect the amountmore » and phase of precipitation associated with atmospheric rivers. ACAPEX took place between January 12, 2015 and March 8, 2015 as part of CalWater 2015, which included four aircraft (DOE G-1, National Oceanic and Atmospheric Administration [NOAA] G-IV and P-3, and National Aeronautics and Space Administration [NASA] ER-2), the NOAA research ship Ron Brown, carrying onboard the AMF2, National Science Foundation (NSF)-sponsored aerosol and precipitation measurements at Bodega Bay, and the California Department of Water Resources extreme precipitation network.« less

Supporting smarter, healthier and greener societies: the dawn of operational environmental information services Some examples from the Copernicus Atmosphere Monitoring Service (CAMS) programme in Europe

NASA Astrophysics Data System (ADS)

Peuch, V. H.

2016-12-01

Operational environmental services are a reality today, as exemplified by the Copernicus Atmospheric Monitoring Service in Europe. Air quality forecasts, information on the long-range transport of dust or of fire plumes or on greenhouse gas fluxes have become reliable enough to be considered by decision makers and to be communicated broadly -making our societies more informed about the changing environment and about the direct link between human activities, atmospheric composition, weather and climate. Many aspects of the value-adding information chains that have been built over the years share commonalities with Numerical Weather Prediction: global and regional numerical models, reflecting both the level of understanding of physical and chemical processes in the atmosphere and the contemporary computing capabilities, are used to blend observations from different in situ and, increasingly, Earth Observation sources. Significantly, the World Meteorological Organisation has recently added a new component to the Global Atmospheric Watch programme in the form of a Science Advisory Group on "Applications". The main objectives of this group are to develop a portfolio of products and services related to atmospheric composition and to demonstrate particularly the usefulness of exchanging chemical observational data in Near-Real-Time. Exchanging best practices worldwide and facilitating the set-up of new applications are also among the activities. Having operational applications does not imply that research efforts to improve environmental monitoring and forecasting services have become obsolete. Quite the contrary: feedbacks and increasingly demanding requirements from users are stimulating steady progress. The last part of the talk will support the idea that atmospheric compositions services are not only an application or an extension of weather services but contribute now also to the core of them. Atmospheric composition information has become indeed of high interest for modelling physical processes and assimilation of meteorological information. There are also exciting developments regarding the medium- to extended range prediction skill, with potential sources of predictability yet to be fully understood and harnessed.

Investigating the contribution of shipping emissions to atmospheric PM2.5 using a combined source apportionment approach.

PubMed

Lang, Jianlei; Zhou, Ying; Chen, Dongsheng; Xing, Xiaofan; Wei, Lin; Wang, Xiaotong; Zhao, Na; Zhang, Yanyun; Guo, Xiurui; Han, Lihui; Cheng, Shuiyuan

2017-10-01

Many studies have been conducted focusing on the contribution of land emission sources to PM 2.5 in China; however, little attention had been paid to other contributions, especially the secondary contributions from shipping emissions to atmospheric PM 2.5 . In this study, a combined source apportionment approach, including principle component analysis (PCA) and WRF-CMAQ simulation, was applied to identify both primary and secondary contributions from ships to atmospheric PM 2.5 . An intensive PM 2.5 observation was conducted from April 2014 to January 2015 in Qinhuangdao, which was close to the largest energy output port of China. The chemical components analysis results showed that the primary component was the major contributor to PM 2.5 , with proportions of 48.3%, 48.9%, 55.1% and 55.4% in spring, summer, autumn and winter, respectively. The secondary component contributed higher fractions in summer (48.2%) and winter (36.8%), but had lower percentages in spring (30.1%) and autumn (32.7%). The hybrid source apportionment results indicated that the secondary contribution (SC) of shipping emissions to PM 2.5 could not be ignored. The annual average SC was 2.7%, which was comparable to the primary contribution (2.9%). The SC was higher in summer (5.3%), but lower in winter (1.1%). The primary contributions to atmospheric PM 2.5 were 3.0%, 2.5%, 3.4% and 2.7% in spring, summer, autumn and winter, respectively. As for the detailed chemical components, the contributions of shipping emissions were 2.3%, 0.5%, 0.1%, 1.0%, 1.7% and 0.1% to elements & sea salt, primary organic aerosol (POA), element carbon (EC), nitrate, sulfate and secondary organic carbon (SOA), respectively. The results of this study will further the understanding of the implications of shipping emissions in PM 2.5 pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

A qualitative assessment of a random process proposed as an atmospheric turbulence model

NASA Technical Reports Server (NTRS)

Sidwell, K.

1977-01-01

A random process is formed by the product of two Gaussian processes and the sum of that product with a third Gaussian process. The resulting total random process is interpreted as the sum of an amplitude modulated process and a slowly varying, random mean value. The properties of the process are examined, including an interpretation of the process in terms of the physical structure of atmospheric motions. The inclusion of the mean value variation gives an improved representation of the properties of atmospheric motions, since the resulting process can account for the differences in the statistical properties of atmospheric velocity components and their gradients. The application of the process to atmospheric turbulence problems, including the response of aircraft dynamic systems, is examined. The effects of the mean value variation upon aircraft loads are small in most cases, but can be important in the measurement and interpretation of atmospheric turbulence data.

Detecting anthropogenic footprints in sea level rise: the role of complex colored noise

NASA Astrophysics Data System (ADS)

Dangendorf, Sönke; Marcos, Marta; Müller, Alfred; Zorita, Eduardo; Jensen, Jürgen

2015-04-01

While there is scientific consensus that global mean sea level (MSL) is rising since the late 19th century, it remains unclear how much of this rise is due to natural variability or anthropogenic forcing. Uncovering the anthropogenic contribution requires profound knowledge about the persistence of natural MSL variations. This is challenging, since observational time series represent the superposition of various processes with different spectral properties. Here we statistically estimate the upper bounds of naturally forced centennial MSL trends on the basis of two separate components: a slowly varying volumetric (mass and density changes) and a more rapidly changing atmospheric component. Resting on a combination of spectral analyses of tide gauge records, ocean reanalysis data and numerical Monte-Carlo experiments, we find that in records where transient atmospheric processes dominate, the persistence of natural volumetric changes is underestimated. If each component is assessed separately, natural centennial trends are locally up to ~0.5 mm/yr larger than in case of an integrated assessment. This implies that external trends in MSL rise related to anthropogenic forcing might be generally overestimated. By applying our approach to the outputs of a centennial ocean reanalysis (SODA), we estimate maximum natural trends in the order of 1 mm/yr for the global average. This value is larger than previous estimates, but consistent with recent paleo evidence from periods in which the anthropogenic contribution was absent. Comparing our estimate to the observed 20th century MSL rise of 1.7 mm/yr suggests a minimum external contribution of at least 0.7 mm/yr. We conclude that an accurate detection of anthropogenic footprints in MSL rise requires a more careful assessment of the persistence of intrinsic natural variability.

Hotspots of Very Short Lived Halocarbons in the Tropical Ocean and Atmosphere

NASA Astrophysics Data System (ADS)

Jia, Y.; Tegtmeier, S.; Quack, B.; Atlas, E. L.

2017-12-01

Very short lived halocarbons (VSLH) with atmospheric lifetimes shorter than 6 months are known to have natural oceanic sources. VSLH have drawn lots of attentions due to their contribution to stratospheric ozone depletion and tropospheric chemistry. VSLH in the ocean show a large spatial variability often with enhanced concentrations in coastal and upwelling regions. It is unclear how this variability in oceanic concentration and emissions impacts the atmospheric VSLH distribution. Such knowledge however is relevant in order to understand their impact on atmospheric chemistry and in order to design meaningful aircraft campaigns and measurement stations. Measurements from three tropical ship campaigns (TransBrom 2009, SHIVA 2011, and OASIS, 2014) suggest localized oceanic "hotspot", regions with very high VSLH emissions from the ocean into the atmosphere. It is also an open question if there's significant impact of these hotspots on the concentrations of VSLH in the atmosphere or if atmospheric transport and mixing obliterates their signals in the atmosphere. In our study, the Lagrangian transport model FLEXPART is used to investigate the atmospheric transport of CHBr3, CH2Br2, and CH3I emitted from the ocean into atmosphere. First, we derive typical atmospheric background concentrations of VSLH from (uniform and non-uniform) oceanic emissions found in the open ocean. In these simulations, the clear structures of meteorological processes (i.e. typhoons and other convective systems) are captured in the VSLHs background concentrations. In a second step, we apply VSLH emissions derived during the ship campaigns to analyze the impacts of the strong oceanic hotspots on the atmospheric VSLH distributions. These hotspots do not show an atmospheric signature if their regional extent is limited, even if their emissions are orders of magnitudes larger than the background emissions. However, if the hotspots extend over a region larger than roughly 0.3° x 0.3° (latitude x longitude), they produce a clear signal of enhanced atmospheric VSLH abundance. Our results will help to understand how oceanic VSLH concentrations, atmospheric transport patterns and atmospheric VSLH distributions are coupled, and predict the maximum mixing ratios that can be expected in the vicinity of oceanic hotspots.

Samples from Martian craters: Origin of the Martian soil by hydrothermal alteration of impact melt deposits and atmospheric interactions with ejecta during crater formation

NASA Technical Reports Server (NTRS)

Newsom, Horton E.

1988-01-01

The origin of the Martian soil is an important question for understanding weathering processes on the Martian surface, and also for understanding the global geochemistry of Mars. Chemical analyses of the soil will provide an opportunity to examine what may be a crustal average, as studies of loess on the Earth have demonstrated. In this regard the origin of the Martian soil is also important for understanding the chemical fractionations that have affected the composition of the soil. Several processes that are likely to contribute to the Martian soil are examined.

Biomonitoring of atmospheric pollution: a novel approach for the evaluation of natural and anthropogenic contribution to atmospheric aerosol particles.

PubMed

Caggiano, Rosa; Calamita, Giuseppe; Sabia, Serena; Trippetta, Serena

2017-03-01

The investigation of the potential natural and anthropogenic contribution to atmospheric aerosol particles by using lichen-bag technique was performed in the Agri Valley (Basilicata region, southern Italy). This is an area of international concern since it houses one of the largest European on-shore reservoirs and the biggest oil/gas pre-treatment plant (i.e., Centro Olio Val d'Agri (COVA)) within an anthropized context. In particular, the concentrations of 17 trace elements (Al, Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Ti, and Zn) were measured in lichen bags exposed in 59 selected monitoring points over periods of 6 months (from October 2011 to April 2012) and 12 months (from October 2011 to October 2012). The general origin of the main air masses affecting the sampling site during the study period was assessed by the back trajectories clustering calculated using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results allowed the identification and characterization of the crustal material, smoke, sea salt, sulfate, and anthropogenic trace element contributions to the atmospheric aerosol particles in the study area. Finally, the application of the trend surface analysis (TSA) allowed the study of the spatial distribution of the considered contributions highlighting the existence of a continuous broad variation of these contributions in the area of interest.

CentNet—A deployable 100-station network for surface exchange research

NASA Astrophysics Data System (ADS)

Oncley, S.; Horst, T. W.; Semmer, S.; Militzer, J.; Maclean, G.; Knudson, K.

2014-12-01

Climate, air quality, atmospheric composition, surface hydrology, and ecological processes are directly affected by the Earth's surface. Complexity of this surface exists at multiple spatial scales, which complicates the understanding of these processes. NCAR/EOL currently provides a facility to the research community to make direct eddy-covariance flux observations to quantify surface-atmosphere interactions. However, just as model resolution has continued to increase, there is a need to increase the spatial density of flux measurements to capture the wide variety of scales that contribute to exchange processes close to the surface. NCAR/EOL now has developed the CentNet facility, that is envisioned to have on the order of 100 surface flux stations deployable for periods of months to years. Each station would measure standard meteorological variables, all components of the surface energy balance (including turbulence fluxes and radiation), atmospheric composition, and other quantities to characterize the surface. Thus, CentNet can support observational research in the biogeosciences, hydrology, urban meteorology, basic meteorology, and turbulence. CentNet has been designed to be adaptable to a wide variety of research problems while keeping operations manageable. Tower infrastructure has been designed to be lightweight, easily deployed, and with a minimal set-up footprint. CentNet uses sensor networks to increase spatial sampling at each station. The data system saves every sample on site to retain flexibility in data analysis. We welcome guidance on development and funding priorities as we build CentNet.

Stable isotopic indicators of nitrous oxide and methane sources in Los Angeles, California

NASA Astrophysics Data System (ADS)

Townsend-Small, A.; Pataki, D.; Tyler, S.; Trumbore, S.

2008-12-01

As urbanization increasingly encroaches upon agricultural landscapes, there are greater potential sources of greenhouse gases and other atmospheric contaminants. Measurements of the isotopic composition of trace gases have the potential to distinguish between pollutant sources and quantify the proportional contribution of agricultural activities to the total atmospheric pool. In this study, we are measuring the isotopic composition of greenhouse gases N2O and CH4 emitted from cropland, animal feeding operations, and urban activities in the South Coast Air Basin in southern California. The ultimate goal of our project is to utilize atmospheric measurements of the isotopic composition of N2O and CH4 combined with studies of source signatures to determine the proportional contributions of cropland, animal operations, and urban sources of greenhouse gases to the atmosphere. Measurements of the δ13C of methane show excellent separation between urban sources, such as vehicle emissions, power plants, oil refineries, landfills, and sewage treatment plants and agricultural sources like cows, biogas, and cattle feedlots. For nitrous oxide, soil N2O sources showed good separation from wastewater treatment facilities using δ15N and δ18O. Within soil N2O sources, the isotopic composition of N2O from cropland soils was similar to N2O emissions from urban turfgrass. These data indicate that nitrification may be as important a source of N2O as denitrification in urban soils. We are also measuring N2O fluxes from soils and from sewage treatment processes, and preliminary data indicate that urban N2O fluxes are higher than initially assumed by managers and regulatory agencies.

Atmospheric Sulfur Cycle Simulated in The Global Model GOCART: Model Description and Global Properties

NASA Technical Reports Server (NTRS)

Chin, Mian; Rood, Richard B.; Lin, Shian-Jiann; Mueller, Jean-Francois; Thompson, Anne M.

2000-01-01

The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate the atmospheric sulfur cycle. The model uses the simulated meteorological data from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). Global sulfur budgets from a 6-year simulation for SO2, sulfate, dimethylsulfide (DMS), and methanesulfonic acid (MSA) are presented in this paper. In a normal year without major volcanic perturbations, about 20% of the sulfate precursor emission is from natural sources (biogenic and volcanic) and 80% is anthropogenic: the same sources contribute 339% and 67% respectively to the total sulfate burden. A sulfate production efficiency of 0.41 - 0.42 is estimated in the model, an efficiency which is defined as a ratio of the amount oi sulfate produced to the total amount of SO2 emitted and produced in the atmosphere. This value indicates that less than half of the SO2 entering the atmosphere contributes to the sulfate production, the rest being removed by dry and wet depositions. In a simulation for 1990, we estimate a total sulfate production of 39 Tg S /yr with 36% and 64% respectively from in-air and in-cloud oxidation of SO2. We also demonstrate that major volcanic eruptions, such as the Mt. Pinatubo eruption in 1991, can significantly change the sulfate formation pathways, distributions, abundance, and lifetime. Comparison with other models shows that the parameterizations for wet removal or wet production of sulfate are the most critical factors in determining the burdens of SO2 and sulfate. Therefore, a priority for future research should be to reduce the large uncertainties associated with the wet physical and chemical processes.

Re-evaluating the 1940s CO2 plateau

NASA Astrophysics Data System (ADS)

Bastos, A.; Ciais, P.; Barichivitch, J.; Brovkin, V.; Gasser, T.; Pongratz, J.; Trudinger, C. M.

2016-12-01

The ice-core record reveals a stabilisation of atmospheric CO2 in the 1940s (the so called "plateau"), in spite of continued emissions from fossil fuel burning (FF) and land-use change (LUC). This stabilisation has been previously attributed to very strong oceanic CO2 uptake, perhaps in response to the El-Niño event in 1940. However, this explanation is questionable, since recent atmospheric CO2 data indicate that El Niño events generally lead to higher atmospheric CO2 growth-rates because of the terrestrial response, and oceanic CO2 measurements indicate the range of variability in the ocean sink has been rather modest in recent decades. We use up-to-date reconstructions of the CO2 sources (FF and LUC), ocean uptake from two different reconstructions and the terrestrial sink (from TRENDY models) over the 20th century to evaluate whether these allow capturing the CO2 plateau and provide further insight about its drivers. While these datasets provide a plausible explanation for most of the 20th century carbon budget, especially since 1970, they overestimate atmospheric CO2 growth rate during the plateau period by 0.9-2.0PgC.yr-1. We test the possible explanations for this mismatch, namely i) the role of natural variability in the ocean sink; ii) the representation of the terrestrial sink response to the climate anomalies during the 1940s by land-surface models; iii) the contribution of land-use processes possibly not represented in the current datasets. We conclude that a strong terrestrial sink concurrent with enhanced oceanic uptake is required to explain the CO2 stabilisation. Tests performed using the OSCAR carbon-cycle model suggest that changes in land-use coinciding with drastic socioeconomic changes during WW2 could plausibly contribute to the additional sink required.

Arctic warming, moisture increase and circulation changes observed in the Ny-Ålesund homogenized radiosonde record

NASA Astrophysics Data System (ADS)

Maturilli, Marion; Kayser, Markus

2017-10-01

Radiosonde measurements obtained at the Arctic site Ny-Ålesund (78.9°N, 11.9°E), Svalbard, from 1993 to 2014 have been homogenized accounting for instrumentation discontinuities by correcting known errors in the manufacturer provided profiles. The resulting homogenized radiosonde record is provided as supplementary material at http://doi.pangaea.de/10.1594/PANGAEA.845373. From the homogenized data record, the first Ny-Ålesund upper-air climatology of wind, temperature and humidity is presented, forming the background for the analysis of changes during the 22-year period. Particularly during the winter season, a strong increase in atmospheric temperature and humidity is observed, with a significant warming of the free troposphere in January and February up to 3 K per decade. This winter warming is even more pronounced in the boundary layer below 1 km, presumably amplified by mesoscale processes including e.g. orographic effects or the boundary layer capping inversion. Though the largest contribution to the increasing atmospheric water vapour column in winter originates from the lowermost 2 km, no increase in the contribution by specific humidity inversions is detected. Instead, we find an increase in the humidity content of the large-scale background humidity profiles. At the same time, the tropospheric flow in winter is found to occur less frequent from northerly directions and to the same amount more frequent from the South. We conclude that changes in the atmospheric circulation lead to an enhanced advection of warm and moist air from lower latitudes to the Svalbard region in the winter season, causing the warming and moistening of the atmospheric column above Ny-Ålesund, and link the observations to changes in the Arctic Oscillation.

First estimates of the contribution of CaCO3 precipitation to the release of CO2 to the atmosphere during young sea ice growth

NASA Astrophysics Data System (ADS)

Geilfus, N.-X.; Carnat, G.; Dieckmann, G. S.; Halden, N.; Nehrke, G.; Papakyriakou, T.; Tison, J.-L.; Delille, B.

2013-01-01

report measurements of pH, total alkalinity, air-ice CO2 fluxes (chamber method), and CaCO3 content of frost flowers (FF) and thin landfast sea ice. As the temperature decreases, concentration of solutes in the brine skim increases. Along this gradual concentration process, some salts reach their solubility threshold and start precipitating. The precipitation of ikaite (CaCO3.6H2O) was confirmed in the FF and throughout the ice by Raman spectroscopy and X-ray analysis. The amount of ikaite precipitated was estimated to be 25 µmol kg-1 melted FF, in the FF and is shown to decrease from 19 to 15 µmol kg-1 melted ice in the upper part and at the bottom of the ice, respectively. CO2 release due to precipitation of CaCO3 is estimated to be 50 µmol kg-1 melted samples. The dissolved inorganic carbon (DIC) normalized to a salinity of 10 exhibits significant depletion in the upper layer of the ice and in the FF. This DIC loss is estimated to be 2069 µmol kg-1 melted sample and corresponds to a CO2 release from the ice to the atmosphere ranging from 20 to 40 mmol m-2 d-1. This estimate is consistent with flux measurements of air-ice CO2 exchange. Our measurements confirm previous laboratory findings that growing young sea ice acts as a source of CO2 to the atmosphere. CaCO3 precipitation during early ice growth appears to promote the release of CO2 to the atmosphere; however, its contribution to the overall release by newly formed ice is most likely minor.

Uncertainty in Earth System Models: Benchmarks for Ocean Model Performance and Validation

NASA Astrophysics Data System (ADS)

Ogunro, O. O.; Elliott, S.; Collier, N.; Wingenter, O. W.; Deal, C.; Fu, W.; Hoffman, F. M.

2017-12-01

The mean ocean CO2 sink is a major component of the global carbon budget, with marine reservoirs holding about fifty times more carbon than the atmosphere. Phytoplankton play a significant role in the net carbon sink through photosynthesis and drawdown, such that about a quarter of anthropogenic CO2 emissions end up in the ocean. Biology greatly increases the efficiency of marine environments in CO2 uptake and ultimately reduces the impact of the persistent rise in atmospheric concentrations. However, a number of challenges remain in appropriate representation of marine biogeochemical processes in Earth System Models (ESM). These threaten to undermine the community effort to quantify seasonal to multidecadal variability in ocean uptake of atmospheric CO2. In a bid to improve analyses of marine contributions to climate-carbon cycle feedbacks, we have developed new analysis methods and biogeochemistry metrics as part of the International Ocean Model Benchmarking (IOMB) effort. Our intent is to meet the growing diagnostic and benchmarking needs of ocean biogeochemistry models. The resulting software package has been employed to validate DOE ocean biogeochemistry results by comparison with observational datasets. Several other international ocean models contributing results to the fifth phase of the Coupled Model Intercomparison Project (CMIP5) were analyzed simultaneously. Our comparisons suggest that the biogeochemical processes determining CO2 entry into the global ocean are not well represented in most ESMs. Polar regions continue to show notable biases in many critical biogeochemical and physical oceanographic variables. Some of these disparities could have first order impacts on the conversion of atmospheric CO2 to organic carbon. In addition, single forcing simulations show that the current ocean state can be partly explained by the uptake of anthropogenic emissions. Combined effects of two or more of these forcings on ocean biogeochemical cycles and ecosystems are challenging to predict since additive or antagonistic effects may occur. A benchmarking tool for accurate assessment and validation of marine biogeochemical outputs will be indispensable as the model community continues to improve ESM developments. It will provide a first order tool in understanding climate-carbon cycle feedbacks.

Central Tibetan Plateau atmospheric trace metals contamination: a 500-year record from the Puruogangri ice core

NASA Astrophysics Data System (ADS)

Beaudon, E.; Gabrielli, P.; Sierra Hernandez, R.; Wegner, A.; Thompson, L. G.

2017-12-01

Since the 1980s, Asia has experienced enormous industrial development from rapid population growth, industrialization and consequent large-scale environmental changes. The inherent generated atmospheric pollution currently contributes to half of all Earth's anthropogenic trace metals emissions. Asian trace metal aerosols, when deposited on glaciers of the surrounding mountains of the Tibetan Plateau (TP), leave a characteristic chemical fingerprint. Interpreting trace element (TE) records from glaciers implies a thorough comprehension of their provenance and temporal variability. It is then essential to discriminate the TEs' natural background components from their anthropogenic components. Here we present 500-year TE records from the Puruogangri ice core (Tibet, China) that provide a highly resolved account of the impact of past atmospheric influences, environmental processes and human activities on the central TP. A decreasing aeolian dust input to the ice cap allowed the detection of an atmospheric pollution signal. The anthropogenic pollution contribution emerges in the record since the early 1900s and increases substantially after 1935. The metallurgy (Zn, Pb and steel smelting) emission products from the former Soviet Union and especially from central Asia likely enhanced the anthropogenic deposition to the Puruogangri ice cap between 1935 and 1980, suggesting that the westerlies served as a conveyor of atmospheric pollution to central Tibet. The impact of this industrial pollution cumulated with that of the hemispheric coal and gasoline combustion which are respectively traced by Sb and Pb enrichment in the ice. The Chinese steel production accompanying the Great Leap Forward (1958-1961) and the Chinese Cultural Revolution (1966-1976) is proposed as a secondary but proximal source of Pb pollution affecting the ice cap between 1958 and 1976. The most recent decade (1980-1992) of the enrichment time series suggests that Puruogangri ice cap recorded the early Sb, Cd, Zn, Pb and Ag pollution originating from developing countries of South (i.e., India) and East (i.e., China) Asia and transported by the summer monsoonal circulation.

Contribution of Atmospheric Diffusion Conditions to the Recent Improvement in Air Quality in China

PubMed Central

Wang, Xiaoyan; Wang, Kaicun; Su, Liangyuan

2016-01-01

This study analyzed hourly mass concentration observations of PM2.5 (particulate matters with diameter less than 2.5 μm) at 512 stations in China from December 2013 to May 2015. We found that the mean concentrations of PM2.5 during the winter and spring of 2015 Dec. 2014 to Feb. 2015 and Mar. 2015 to May 2015) decreased by 20% and 14% compared to the previous year, respectively. Hazardous air-quality days decreased by 11% in 2015 winter, with more frequent good to unhealthy days; and the good and moderate air-quality days in 2015 spring increased by 9% corresponding to the less occurrence of unhealthy conditions. We compared the atmospheric diffusion conditions during these two years and quantified its contribution to the improvement of air quality during the first half of 2015 over China. Our results show that during the 2015 winter and spring, 70% and 57% of the 512 stations experienced more favorable atmospheric diffusion conditions compared to those of previous year. Over central and northern China, approximately 40% of the total decrease in PM2.5 during the 2015 winter can be attributed to the favorable atmospheric diffusion conditions. The atmospheric diffusion conditions during the spring of 2015 were not as favorable as in winter; and the average contributions of the atmospheric conditions were slight. PMID:27805030

Cloud and boundary layer interactions over the Arctic sea-ice in late summer

NASA Astrophysics Data System (ADS)

Shupe, M. D.; Persson, P. O. G.; Brooks, I. M.; Tjernström, M.; Sedlar, J.; Mauritsen, T.; Sjogren, S.; Leck, C.

2013-05-01

Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back trajectory analyses suggest that these warm airmasses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these airmasses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.

Cloud and boundary layer interactions over the Arctic sea ice in late summer

NASA Astrophysics Data System (ADS)

Shupe, M. D.; Persson, P. O. G.; Brooks, I. M.; Tjernström, M.; Sedlar, J.; Mauritsen, T.; Sjogren, S.; Leck, C.

2013-09-01

Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back-trajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.

Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China.

PubMed

Shen, Jianlin; Liu, Jieyun; Li, Yong; Li, Yuyuan; Wang, Yi; Liu, Xuejun; Wu, Jinshui

2014-09-01

Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China. Copyright © 2014. Published by Elsevier B.V.

Atmospheric deposition of mercury in Atlantic Forest and ecological risk to soil fauna

NASA Astrophysics Data System (ADS)

Cristhy Buch, Andressa; Cabral Teixeira, Daniel; Fernandes Correia, Maria Elizabeth; Vieira Silva-Filho, Emmanoel

2014-05-01

The increasing levels of mercury (Hg) found in the atmosphere nowadays has a great contribution from anthropogenic sources and has been a great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. Certainly, the petroleum refineries have significant contribution, seen that 100 million m3 of crude oil are annually processed. These refineries contribute with low generation of solid waste; however, a large fraction of Hg can be emitted to the atmosphere. There are sixteen refineries in Brazil, three of them located in the state of Rio de Janeiro. The Hg is a toxic and hazardous trace element, naturally found in the earth crust. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of great importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transfer to the soil through litterfall, which play an important role as Hg sink. The Atlantic Forest of Brazil is the greater contributor of fauna and flora biodiversity in the world and, according to recent studies, this biome has the highest concentrations of mercury in litter in the world, as well as in China, at Subtropical Forest. Ecotoxicological assessments can predict the potential ecological risk of Hg toxicity in the soil can lead to impact the soil fauna and indirectly other trophic levels of the food chain within one or more ecosystems. This study aims to determine mercury levels that represent risks to diversity and functioning of soil fauna in tropical forest soils. The study is conducted in two forest areas inserted into conservation units of Rio de Janeiro state. One area is located next to an important petroleum refinery in activity since fifty-two years ago, whereas the other one is located next to other refinery under construction (beginning activities in 2015), which will be the largest refinery of Brazil and, consequently, with less anthropogenic influences for the moment. Ecological risk assessments are conducted together with ecotoxicological tests in natural and artificial tropical soils, using exotic and native species of the soil fauna, naturally present in the area of study, in order to determine the risk of mercury in soil and litter in tropical forest. Previous results confirm higher concentrations of mercury in litter and soil of the forest area closest to the operating refinery. The presence of Hg seems to select the size of the organisms as well as the abundance and diversity of the soil fauna that remain in tropical forest.

Middle Atmosphere Program. Handbook for MAP, Volume 10

NASA Technical Reports Server (NTRS)

Taubenheim, J. (Editor)

1984-01-01

The contributions of ground based investigations to the study of middle atmospheric phenomena are addressed. General topics include diagnostics of the middle atmosphere from D region properties, winter anomaly, seasonal variations and disturbances, dynamics and theoretical models, ground based tracking of winds and waves, lower thermosphere phenomena, and solar-terrestrial influences.

Carbon content of common airborne fungal species and fungal contribution to aerosol organic carbon in a subtropical city

NASA Astrophysics Data System (ADS)

Cheng, Jessica Y. W.; Chan, Chak K.; Lee, C.-T.; Lau, Arthur P. S.

Interest in the role and contribution of fungi to atmospheric aerosols and processes grows in the past decade. Substantial data or information such as fungal mass or carbon loading to ambient aerosols is however still lacking. This study aimed to quantify the specific organic carbon content (OC per spore) of eleven fungal species commonly found airborne in the subtropics, and estimated their contribution to organic carbon in aerosols. The specific OC contents showed a size-dependent relationship ( r = 0.64, p < 0.05) and ranged from 3.6 to 201.0 pg carbon per spore or yeast cell, giving an average of 6.0 pg carbon per spore (RSD 51%) for spore or cell size less than 10 μm. In accounting for natural variations in the composition and abundance of fungal population, weighted-average carbon content for field samples was adopted using the laboratory determined specific OC values. An average of 5.97 pg carbon per spore (RSD 3.8%) was enumerated from 28 field samples collected at the university campus. The mean fungal OC concentration was 3.7, 6.0 and 9.7 ng m -3 in PM 2.5, PM 2.5-10 and PM 10, respectively. These corresponded to 0.1%, 1.2% and 0.2% of the total OC in PM 2.5, PM 2.5-10 and PM 10, respectively. In the study period, rain provided periods with low total OC but high fungal prevalence and fungi contributed 7-32% OC in PM 2.5-10 or 2.4-7.1% OC in PM 10. More extensive studies are deserved to better understand the spatial-, temporal- and episodic dependency on the fungal OC contribution to the atmospheric aerosols.

Changes in the Martian atmosphere induced by auroral electron precipitation

NASA Astrophysics Data System (ADS)

Shematovich, V. I.; Bisikalo, D. V.; Gérard, J.-C.; Hubert, B.

2017-09-01

Typical auroral events in the Martian atmosphere, such as discrete and diffuse auroral emissions detected by UV spectrometers onboard ESA Mars Express and NASA MAVEN, are investigated. Auroral electron kinetic energy distribution functions and energy spectra of the upward and downward electron fluxes are obtained by electron transport calculations using the kinetic Monte Carlo model. These characteristics of auroral electron fluxes make it possible to calculate both the precipitation-induced changes in the atmosphere and the observed manifestations of auroral events on Mars. In particular, intensities of discrete and diffuse auroral emissions in the UV and visible wavelength ranges (Soret et al., 2016; Bisikalo et al., 2017; Gérard et al., 2017). For these conditions of auroral events, the analysis is carried out, and the contribution of the fluxes of precipitating electrons to the heating and ionization of the Martian atmosphere is estimated. Numerical calculations show that in the case of discrete auroral events the effect of the residual crustal magnetic field leads to a significant increase in the upward fluxes of electrons, which causes a decrease in the rates of heating and ionization of the atmospheric gas in comparison with the calculations without taking into account the residual magnetic field. It is shown that all the above-mentioned impact factors of auroral electron precipitation processes should be taken into account both in the photochemical models of the Martian atmosphere and in the interpretation of observations of the chemical composition and its variations using the ACS instrument onboard ExoMars.

The Panchromatic Comparative Exoplanetary Treasury Program

NASA Astrophysics Data System (ADS)

Sing, David

2016-10-01

HST has played the definitive role in the characterization of exoplanets and from the first planets available, we have learned that their atmospheres are incredibly diverse. The large number of transiting planets now available has prompted a new era of atmospheric studies, where wide scale comparative planetology is now possible. The atmospheric chemistry of cloud/haze formation and atmospheric mass-loss are a major outstanding issues in the field of exoplanets, and we seek to make progress gaining insight into their underlying physical process through comparative studies. Here we propose to use Hubble's full spectroscopic capabilities to produce the first large-scale, simultaneous UVOIR comparative study of exoplanets. With full wavelength coverage, an entire planet's atmosphere can be probed simultaneously and with sufficient numbers of planets, we can statistically compare their features with physical parameters for the first time. This panchromatic program will build a lasting HST legacy, providing the UV and blue-optical spectra unavailable to JWST. From these observations, chemistry over a wide range of physical environments will be probed, from the hottest condensates to much cooler planets where photochemical hazes could be present. Constraints on aerosol size and composition will help unlock our understanding of clouds and how they are suspended at such high altitudes. Notably, there have been no large transiting UV HST programs, and this panchromatic program will provide a fundamental legacy contribution to atmospheric escape of small exoplanets, where the mass loss can be significant and have a major impact on the evolution of the planet itself.

A new method for assessing the contribution of Primary Biological Atmospheric Particles to the mass concentration of the atmospheric aerosol.

PubMed

Perrino, Cinzia; Marcovecchio, Francesca

2016-02-01

Primary Biologic Atmospheric Particles (PBAPs) constitute an interesting and poorly investigated component of the atmospheric aerosol. We have developed and validated a method for evaluating the contribution of overall PBAPs to the mass concentration of atmospheric particulate matter (PM). The method is based on PM sampling on polycarbonate filters, staining of the collected particles with propidium iodide, observation at epifluorescence microscope and calculation of the bioaerosol mass using a digital image analysis software. The method has been also adapted to the observation and quantification of size-segregated aerosol samples collected by multi-stage impactors. Each step of the procedure has been individually validated. The relative repeatability of the method, calculated on 10 pairs of atmospheric PM samples collected side-by-side, was 16%. The method has been applied to real atmospheric samples collected in the vicinity of Rome, Italy. Size distribution measurements revealed that PBAPs was mainly in the coarse fraction of PM, with maxima in the range 5.6-10 μm. 24-h samples collected during different period of the year have shown that the concentration of bioaerosol was in the range 0.18-5.3 μg m(-3) (N=20), with a contribution to the organic matter in PM10 in the range 0.5-31% and to the total mass concentration of PM10 in the range 0.3-18%. The possibility to determine the concentration of total PBAPs in PM opens up interesting perspectives in terms of studying the health effects of these components and of increasing our knowledge about the composition of the organic fraction of the atmospheric aerosol. Copyright © 2015 Elsevier Ltd. All rights reserved.

Long term atmospheric aerosol characterization in the Amazon Basin

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Gerab, Fábio; Yamasoe, Marcia A.

This chapter presents a characterization of atmospheric aerosols collected in different places in the Amazon Basin. Both the biogenic aerosol emission from the forest and the particulate material which is emitted to the atmosphere due to the large scale man-made burns during the dry season were studied. The samples were collected during a three year period at three different locations in the Amazon (Cuiabá, Alta Floresta and Serra do Navio), using stacked filter units. Aerosol samples were also collected directly over fires of cerrado vegetation and tropical primary forest burns The samples were analyzed using several techniques for a number of elements. Gravimetric analyses were used to determine the total atmospheric aerosol concentration. Multivariate statistical analysis was used in order to identify and characterize the sources of the atmospheric aerosol present in the sampled regions. Cerrado burning emissions were enriched compared to forest ones, specially for Cl, K and Zn. High atmospheric aerosol concentrations were observed in large amazonian areas due to emissions from man-made burns in the period from June to September. The emissions from burns dominate the fine fraction of the atmospheric aerosol with characteristic high contents of black carbon, S and K. Aerosols emitted in biomass burning process are correlated to the increase in the aerosol optical thickness of the atmosphere during the Amazonian dry season. The Serra do Navio aerosol is characterized by biogenic emissions with strong marine influence. The presence of trace elements characteristic of soil particulate associated with this marine contribution indicates the existence of aerosol transport from Africa to South America. Similar composition characteristics were observed in the biogenic emission aerosols from Serra do Navio and Alta Floresta.

Improving SLCF Science in the Himalayan Region: ICIMOD's Atmosphere Initiative

NASA Astrophysics Data System (ADS)

Panday, A. K.; Pradhan, B. B.; Surapipith, V.

2013-12-01

What fraction of the black carbon arriving on Yala Glacier in Langtang, Nepal, is from cooking fires in the houses in the valley below? What fraction is from elsewhere in rural Nepal? What fraction is from industrial and transport sources in Kathmandu? What fraction is from northern India and beyond? What fraction is from the high altitude forest fires that take place during March or April? Effectively mitigating the impacts of black carbon and other short-lived climate forcers requires detailed understanding not just of emissions and impacts, but also of the atmospheric transport pathways that connect the two. In mountainous areas of the Hindu-Kush Himalaya detailed quantitative knowledge about emissions, atmospheric processes, and impacts is still largely missing. The International Centre for Integrated Mountain Development (ICIMOD) is an intergovernmental organization covering Afghanistan, Pakistan, India, Nepal, China, Bhutan, Bangladesh, and Myanmar. ICIMOD's recently established Atmosphere Initiative not only assesses mitigation options and contributes to policy and capacity building in the region, but also works actively to promote collaboration among researchers in the region, while building up an in-house team whose research will address key questions about SLCF. In Spring 2013 ICIMOD's Atmosphere Initiative, in collaboration with the Institute for Advanced Sustainability Studies (IASS) in Potsdam, Germany, carried out the largest field campaign to date in Nepal, hosting instruments belonging to dozens of institutions around the world, at nine field site within and upwind of the Kathmandu Valley, Nepal. The dataset that has been collected gives unprecedented insights into the emissions and atmospheric processes taking place downwind of and within the largest urban agglomeration in the Himalaya region. Meanwhile, in collaboration with national partner institutions, ICIMOD is in the process of setting up one atmospheric observatory each in Bhutan and in Nepal. Each will be on a mountain peak overlooking the Indo-Gangetic Plains. A building will house laboratories and visitor space, and will have a small tower. Each site will be equipped with a Picarro G2401 analyzer for CO, CO¬2, methane and water vapor, aerosol filter samplers, as well as instruments to measure black carbon, ozone, aerosol size distribution, aerosol scattering, cloud condensation nuclei, solar radiation, aerosol optical depth, and meteorology. Together with output from ICIMOD's new atmospheric modeling centre, the data from the sites will allow quantifying the flux of pollutants from the Indo-Gangetic Plains towards the high Himalaya, and to estimate emissions of SLCFs within the Himalayan foothills region. The infrastructure at both observatory sites is designed to accommodate training and future expansion as well as to host visiting instruments.

The 30-60-day Intraseasonal Variability of Sea Surface Temperature in the South China Sea dur1ing May-September

NASA Astrophysics Data System (ADS)

Mao, Jiangyu; Wang, Ming

2018-05-01

This study investigates the structure and propagation of intraseasonal sea surface temperature (SST) variability in the South China Sea (SCS) on the 30-60-day timescale during boreal summer (May-September). TRMM-based SST, GODAS oceanic reanalysis and ERA-Interim atmospheric reanalysis datasets from 1998 to 2013 are used to examine quantitatively the atmospheric thermodynamic and oceanic dynamic mechanisms responsible for its formation. Power spectra show that the 30-60-day SST variability is predominant, accounting for 60% of the variance of the 10-90-day variability over most of the SCS. Composite analyses demonstrate that the 30-60-day SST variability is characterized by the alternate occurrence of basin-wide positive and negative SST anomalies in the SCS, with positive (negative) SST anomalies accompanied by anomalous northeasterlies (southwesterlies). The transition and expansion of SST anomalies are driven by the monsoonal trough-ridge seesaw pattern that migrates northward from the equator to the northern SCS. Quantitative diagnosis of the composite mixed-layer heat budgets shows that, within a strong 30-60-day cycle, the atmospheric thermal forcing is indeed a dominant factor, with the mixed-layer net heat flux (MNHF) contributing around 60% of the total SST tendency, while vertical entrainment contributes more than 30%. However, the entrainment-induced SST tendency is sometimes as large as the MNHF-induced component, implying that ocean processes are sometimes as important as surface fluxes in generating the 30-60-day SST variability in the SCS.

The contribution of the ARIEL space mission to the study of planetary formation

NASA Astrophysics Data System (ADS)

Turrini, D.; Miguel, Y.; Zingales, T.; Piccialli, A.; Helled, R.; Vazan, A.; Oliva, F.; Sindoni, G.; Panić, O.; Leconte, J.; Min, M.; Pirani, S.; Selsis, F.; Coudé du Foresto, V.; Mura, A.; Wolkenberg, P.

2018-01-01

The study of extrasolar planets and of the Solar System provides complementary pieces of the mosaic represented by the process of planetary formation. Exoplanets are essential to fully grasp the huge diversity of outcomes that planetary formation and the subsequent evolution of the planetary systems can produce. The orbital and basic physical data we currently possess for the bulk of the exoplanetary population, however, do not provide enough information to break the intrinsic degeneracy of their histories, as different evolutionary tracks can result in the same final configurations. The lessons learned from the Solar System indicate us that the solution to this problem lies in the information contained in the composition of planets. The goal of the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL), one of the three candidates as ESA M4 space mission, is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres, which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk composition across all main cosmochemical elements. In this work we will review the most outstanding open questions concerning the way planets form and the mechanisms that contribute to create habitable environments that the compositional information gathered by ARIEL will allow to tackle.

Quantifying and Comparing Effects of Climate Engineering Methods on the Earth System

NASA Astrophysics Data System (ADS)

Sonntag, Sebastian; Ferrer González, Miriam; Ilyina, Tatiana; Kracher, Daniela; Nabel, Julia E. M. S.; Niemeier, Ulrike; Pongratz, Julia; Reick, Christian H.; Schmidt, Hauke

2018-02-01

To contribute to a quantitative comparison of climate engineering (CE) methods, we assess atmosphere-, ocean-, and land-based CE measures with respect to Earth system effects consistently within one comprehensive model. We use the Max Planck Institute Earth System Model (MPI-ESM) with prognostic carbon cycle to compare solar radiation management (SRM) by stratospheric sulfur injection and two carbon dioxide removal methods: afforestation and ocean alkalinization. The CE model experiments are designed to offset the effect of fossil-fuel burning on global mean surface air temperature under the RCP8.5 scenario to follow or get closer to the RCP4.5 scenario. Our results show the importance of feedbacks in the CE effects. For example, as a response to SRM the land carbon uptake is enhanced by 92 Gt by the year 2100 compared to the reference RCP8.5 scenario due to reduced soil respiration thus reducing atmospheric CO2. Furthermore, we show that normalizations allow for a better comparability of different CE methods. For example, we find that due to compensating processes such as biogeophysical effects of afforestation more carbon needs to be removed from the atmosphere by afforestation than by alkalinization to reach the same global warming reduction. Overall, we illustrate how different CE methods affect the components of the Earth system; we identify challenges arising in a CE comparison, and thereby contribute to developing a framework for a comparative assessment of CE.

Modelling the contribution of biogenic volatile organic compounds to new particle formation in the Jülich plant atmosphere chamber

NASA Astrophysics Data System (ADS)

Roldin, P.; Liao, L.; Mogensen, D.; Dal Maso, M.; Rusanen, A.; Kerminen, V.-M.; Mentel, T. F.; Wildt, J.; Kleist, E.; Kiendler-Scharr, A.; Tillmann, R.; Ehn, M.; Kulmala, M.; Boy, M.

2015-09-01

We used the Aerosol Dynamics gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM) to simulate the contribution of BVOC plant emissions to the observed new particle formation during photooxidation experiments performed in the Jülich Plant-Atmosphere Chamber and to evaluate how well smog chamber experiments can mimic the atmospheric conditions during new particle formation events. ADCHAM couples the detailed gas-phase chemistry from Master Chemical Mechanism with a novel aerosol dynamics and particle phase chemistry module. Our model simulations reveal that the observed particle growth may have either been controlled by the formation rate of semi- and low-volatility organic compounds in the gas phase or by acid catalysed heterogeneous reactions between semi-volatility organic compounds in the particle surface layer (e.g. peroxyhemiacetal dimer formation). The contribution of extremely low-volatility organic gas-phase compounds to the particle formation and growth was suppressed because of their rapid and irreversible wall losses, which decreased their contribution to the nano-CN formation and growth compared to the atmospheric situation. The best agreement between the modelled and measured total particle number concentration (R2 > 0.95) was achieved if the nano-CN was formed by kinetic nucleation involving both sulphuric acid and organic compounds formed from OH oxidation of BVOCs.

The contributions of Lewis Fry Richardson to drainage theory, soil physics, and the soil-plant-atmosphere continuum

NASA Astrophysics Data System (ADS)

Knight, John; Raats, Peter

2016-04-01

The EGU Division on Nonlinear Processes in Geophysics awards the Lewis Fry Richardson Medal. Richardson's significance is highlighted in http://www.egu.eu/awards-medals/portrait-lewis-fry-richardson/, but his contributions to soil physics and to numerical solutions of heat and diffusion equations are not mentioned. We would like to draw attention to those little known contributions. Lewis Fry Richardson (1881-1953) made important contributions to many fields including numerical weather prediction, finite difference solutions of partial differential equations, turbulent flow and diffusion, fractals, quantitative psychology and studies of conflict. He invented numerical weather prediction during World War I, although his methods were not successfully applied until 1950, after the invention of fast digital computers. In 1922 he published the book `Numerical weather prediction', of which few copies were sold and even fewer were read until the 1950s. To model heat and mass transfer in the atmosphere, he did much original work on turbulent flow and defined what is now known as the Richardson number. His technique for improving the convergence of a finite difference calculation is known as Richardson extrapolation, and was used by John Philip in his 1957 semi-analytical solution of the Richards equation for water movement in unsaturated soil. Richardson's first papers in 1908 concerned the numerical solution of the free surface problem of unconfined flow of water in saturated soil, arising in the design of drain spacing in peat. Later, for the lower boundary of his atmospheric model he needed to understand the movement of heat, liquid water and water vapor in what is now called the vadose zone and the soil plant atmosphere system, and to model coupled transfer of heat and flow of water in unsaturated soil. Finding little previous work, he formulated partial differential equations for transient, vertical flow of liquid water and for transfer of heat and water vapor. He paid considerable attention to the balances of water and energy at the soil-atmosphere and plant-atmosphere interfaces, making use of the concept of transfer resistance introduced by Brown and Escombe (1900) for leaf-atmosphere interfaces. He incorporated finite difference versions of all equations into his numerical weather forecasting model. From 1916, Richardson drove an ambulance in France in World War I, did weather computations in his spare time, and wrote a draft of his book. Later researchers such as L.A. Richards, D.A. de Vries and J.R. Philip from the 1930s to the 1950s were unaware that Richardson had anticipated many of their ideas on soil liquid water, heat, water vapor, and the soil-plant-atmosphere system. The Richards (1931) equation could rightly be called the Richardson (1922) equation! Richardson (1910) developed what we now call the Crank Nicolson implicit method for the heat or diffusion equation. To save effort, he used an explicit three level method after the first time step. Crank and Nicolson (1947) pointed out the instability in the explicit method, and used his implicit method for all time steps. Hanks and Bowers (1962) adapted the Crank Nicolson method to solve the Richards equation. So we could say that Hanks and Bowers used the Richardson finite difference method to solve the Richardson equation for soil water flow!

Impact induced dehydration of serpentine and the evolution of planetary atmospheres

NASA Technical Reports Server (NTRS)

Lange, M. A.; Ahrens, T. J.

1982-01-01

Results of shock recovery experiments carried out on antigorite serpentine Mg3Si2O5(OH)4 are reported. The main objective of the present study is the determination of critical shock pressures for partial and complete dehydration of serpentine under shock loading. It is pointed out that serpentine and serpentine-like layer silicates are the major water-bearing phases in carbonaceous chondrites. It appears that these minerals, and a poorly defined cometary contribution, were the most likely water-bearing phases in accreting planetesimals which led to the formation of the terrestrial planets. The obtained results imply that the process of impact induced devolatilization of volatile bearing minerals during accretion is likely to have occurred on earth. The findings lend support to the model of a terrestrial atmosphere/hydrosphere forming during the later stages of accretion of the earth.

The reinvigoration of the Southern Ocean carbon sink.

PubMed

Landschützer, Peter; Gruber, Nicolas; Haumann, F Alexander; Rödenbeck, Christian; Bakker, Dorothee C E; van Heuven, Steven; Hoppema, Mario; Metzl, Nicolas; Sweeney, Colm; Takahashi, Taro; Tilbrook, Bronte; Wanninkhof, Rik

2015-09-11

Several studies have suggested that the carbon sink in the Southern Ocean-the ocean's strongest region for the uptake of anthropogenic CO2 -has weakened in recent decades. We demonstrated, on the basis of multidecadal analyses of surface ocean CO2 observations, that this weakening trend stopped around 2002, and by 2012, the Southern Ocean had regained its expected strength based on the growth of atmospheric CO2. All three Southern Ocean sectors have contributed to this reinvigoration of the carbon sink, yet differences in the processes between sectors exist, related to a tendency toward a zonally more asymmetric atmospheric circulation. The large decadal variations in the Southern Ocean carbon sink suggest a rather dynamic ocean carbon cycle that varies more in time than previously recognized. Copyright © 2015, American Association for the Advancement of Science.

Late Veneer collisions and their impact on the evolution of Venus (PS Division Outstanding ECS Award Lecture)

NASA Astrophysics Data System (ADS)

Gillmann, Cedric; Golabek, Gregor; Tackley, Paul; Raymond, Sean

2017-04-01

During the end of the accretion, the so-called Late Veneer phase, while the bulk of the mass of terrestrial planets is already in place, a substantial number of large collisions can still occur. Those impacts are thought to be responsible for the repartition of the Highly Siderophile Elements. They are also susceptible to have a strong effect on volatile repartition and mantle convection. We study how Late Veneer impacts modify the evolution of Venus and its atmosphere, using a coupled numerical simulation. We focus on volatile exchanges and their effects on surface conditions. Mantle dynamics, volcanism and degassing processes lead to an input of gases in the atmosphere and are modeled using the StagYY mantle convection code. Volatile losses are estimated through atmospheric escape modeling. It involves two different aspects: hydrodynamic escape (0-500 Myr) and non-thermal escape. Hydrodynamic escape is massive but occurs only when the solar energy input is strong. Post 4 Ga escape from non-thermal processes is comparatively low but long-lived. The resulting state of the atmosphere is used to the calculate greenhouse effect and surface temperature, through a one-dimensional gray radiative-convective model. Large impacts are capable of contributing to (i) atmospheric escape, (ii) volatile replenishment and (iii) energy transfer to the mantle. We test various impactor compositions, impact parameters (velocity, location, size, and timing) and eroding power. Scenarios we tested are adapted from numerical stochastic simulations (Raymond et al., 2013). Impactor sizes are dominated by large bodies (R>500 km). Erosion of the atmosphere by a few large impacts appears limited. Swarms of smaller more mass-effective impactors seem required for this effect to be significant. Large impactors have two main effects on the atmosphere. They can (i) create a large input of volatile from the melting they cause during the impact and through the volatiles they carry. This leads to an increase in atmosphere density and surface temperatures. However, early impacts can also (ii) deplete the mantle of Venus and (assuming strong early escape) ultimately remove volatiles from the system, leading to lower late degassing and lower surface temperatures. The competition between those effects depends on the time of the impact, which directly governs the strength of atmospheric losses.

Structure-activity relationships to estimate the effective Henry's law coefficients of organics of atmospheric interest

NASA Astrophysics Data System (ADS)

Raventos-Duran, Teresa; Valorso, Richard; Aumont, Bernard; Camredon, Marie

2010-05-01

The oxidation of volatile organic compounds emitted in the atmosphere involves complex reaction mechanisms which leads to the formation of oxygenated organic intermediates, usually denoted as secondary organics. The fate of these secondary organics remains poorly quantified due to a lack of information about their speciation, distribution and evolution in the gas and condensed phases. A significant fraction of secondary organics may dissolve into the tropospheric aqueous phase owing to the presence of polar moieties generated during the oxidation processes. The partitioning of organics between the gas and the aqueous atmospheric phases is usually described in the basis of Henry's law. Atmospheric models require a knowledge of the Henry's law coefficient (H) for every water soluble organic species described in the chemical mechanism. Methods that can predict reliable H values for the vast number of organic compounds are therefore required. We have compiled a data set of experimental Henry's law constants for compounds bearing functional groups of atmospheric relevance. This data set was then used to develop GROMHE, a structure activity relationship to predict H values based on a group contribution approach. We assessed its performance with two other available estimation methods. The results show that for all these methods the reliability of the estimates decreases with increasing solubility. We discuss differences between methods and found that GROMHE had greater prediction ability.

Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy

PubMed Central

Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

2016-01-01

Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident. PMID:27301319

Degradation of reactive blue 19 by needle-plate non-thermal plasma in different gas atmospheres: Kinetics and responsible active species study assisted by CFD calculations.

PubMed

Sun, Yu; Liu, Yanan; Li, Rui; Xue, Gang; Ognier, Stéphanie

2016-07-01

This study investigated the degradation of a model organic compound, reactive blue (RB-19), in aqueous solution using a needle-plate non-thermal plasma (NTP) reactor, which was operated using three gas atmospheres (Ar, air, O2) at room temperature and atmospheric pressure. The relative discharge and degradation parameters, including the peak to peak applied voltage, power, ozone generation, pH, decolorization rates, energy density and the total organic carbon (TOC) reduction were analyzed to determine the various dye removal efficiencies. The decolorization rate for Ar, air and O2 were 59.9%, 49.6% and 89.8% respectively at the energy density of 100 kJ/L. The best TOC reduction was displayed by Ar with about 8.8% decrease, and 0% with O2 and air atmospheres. This phenomenon could be explained by the formation of OH• and O3 in the Ar and O2 atmospheres, which are responsible for increased mineralization and efficient decolorization. A one-dimension model was developed using software COMSOL to simulate the RB-19-ozone reaction and verify the experiments by comparing the simulated and experimental results. It was determined that ozone plays the most important role in the dye removal process, and the ozone contribution rate ranged from 0.67 to 0.82. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy

NASA Astrophysics Data System (ADS)

Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

2016-06-01

Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident.

Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy.

PubMed

Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

2016-06-15

Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident.

Estimation of continental precipitation recycling

NASA Technical Reports Server (NTRS)

Brubaker, Kaye L.; Entekhabi, Dara; Eagleson, P. S.

1993-01-01

The total amount of water that precipitates on large continental regions is supplied by two mechanisms: 1) advection from the surrounding areas external to the region and 2) evaporation and transpiration from the land surface within the region. The latter supply mechanism is tantamount to the recycling of precipitation over the continental area. The degree to which regional precipitation is supplied by recycled moisture is a potentially significant climate feedback mechanism and land surface-atmosphere interaction, which may contribute to the persistence and intensification of droughts. Gridded data on observed wind and humidity in the global atmosphere are used to determine the convergence of atmospheric water vapor over continental regions. A simplified model of the atmospheric moisture over continents and simultaneous estimates of regional precipitation are employed to estimate, for several large continental regions, the fraction of precipitation that is locally derived. The results indicate that the contribution of regional evaporation to regional precipitation varies substantially with location and season. For the regions studied, the ratio of locally contributed to total monthly precipitation generally lies between 0. 10 and 0.30 but is as high as 0.40 in several cases.

Effect of nitrogen addition to ozone generation characteristics by diffuse and filamentary dielectric barrier discharges at atmospheric pressure

NASA Astrophysics Data System (ADS)

Osawa, Naoki; Tsuji, Takafumi; Ogiso, Ryota; Yoshioka, Yoshio

2017-05-01

Ozone is widely used for gas treatment, advanced oxidation processes, microorganisms inactivation, etc. In this research, we investigated the effect of nitrogen addition to ozone generation characteristics by atmospheric pressure Townsend discharge (APTD) type and filamentary dielectric barrier discharge (DBD) type ozone generators. The result showed that the ozone generated by the filamentary DBD increases rapidly with the increase of O2 content, and is higher than that by the APTD. On the other hand, it is interesting that the ozone generated by the APTD gradually decreases with the increase of O2 content. In order to clarify why the characteristics of ozone generation by the two kinds of discharge modes showed different dependency to the N2 content, we analyzed the exhaust gas composition using FTIR spectroscopy and calculated the rate coefficients using BOLSIG+ code. As a result, we found that although O2 content decreased with increasing N2 content, additional O atoms produced by excited N2 molecules contribute to ozone generation in case of APTD. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

Sources and Fate of Reactive Carbon over North America

NASA Astrophysics Data System (ADS)

Chen, X.; Millet, D. B.; Singh, H. B.; Wisthaler, A.

2016-12-01

We apply a high-resolution chemical transport model (GEOS-Chem CTM at 0.25°×0.3125°) to generate, a comprehensive gas-phase reactive carbon budget over North America. Based on state-of-science source inventories and known chemistry, we find in the model that biogenic sources dominate the overall reactive carbon budget, with 49, 15, 4, and 39 TgC, respectively, introduced to the North American atmosphere from the biosphere, anthropogenic sources, fires, and from methane oxidation in 2013. Biogenic and anthropogenic non-methane volatile organic compounds contribute 60% and 10%, respectively, to the total OH reactivity over the Southeast US, along with other contributions from methane and inorganics. Oxidation to CO and CO2 then represents the overwhelming fate of that reactive carbon, with 65, 15, 7 and 5 TgC, respectively, oxidized to produce CO/CO2, dry deposited, wet deposited and transported (net) out of North America. We confront this simulation with an ensemble of recent airborne measurements over North America (SEAC4RS, SENEX, DISCOVER-AQ, DC3) and interpret the model-measurement comparisons in terms of their implications for current understanding of atmospheric reactive carbon and the processes driving its distribution.

Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

NASA Astrophysics Data System (ADS)

Mostofa, Khan M. G.; Liu, Cong-Qiang; Zhai, WeiDong; Minella, Marco; Vione, Davide; Gao, Kunshan; Minakata, Daisuke; Arakaki, Takemitsu; Yoshioka, Takahito; Hayakawa, Kazuhide; Konohira, Eiichi; Tanoue, Eiichiro; Akhand, Anirban; Chanda, Abhra; Wang, Baoli; Sakugawa, Hiroshi

2016-03-01

Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3-, and CO32-) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.

Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

NASA Astrophysics Data System (ADS)

Mostofa, K. M. G.; Liu, C.-Q.; Zhai, W. D.; Minella, M.; Vione, D.; Gao, K.; Minakata, D.; Arakaki, T.; Yoshioka, T.; Hayakawa, K.; Konohira, E.; Tanoue, E.; Akhand, A.; Chanda, A.; Wang, B.; Sakugawa, H.

2015-07-01

Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3-, and CO32-) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different time scales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.

Precipitation recycling as a mechanism for ecoclimatological stability through local and non-local interactions

NASA Astrophysics Data System (ADS)

Dominguez, Francina

This study is the first to analyze the mechanisms that drive precipitation recycling variability at the daily to intraseasonal timescale. A new Dynamic Precipitation Recycling model is developed which, unlike previous models, includes the moisture storage term in the equation of conservation of atmospheric moisture. As shown using scaling analysis, the moisture storage term is non-negligible at small time scales, so the new model enables us to analyze precipitation recycling variability at shorter timescales than traditional models. The daily to intraseasonal analysis enables us to uncover key relationships between recycling and the moisture and energy fluxes. In the second phase of this work, a spatiotemporal analysis of daily precipitation recycling is performed over two regions of North America: the Midwestern United States, and the North American Monsoon System (NAMS) region. These regions were chosen because they present contrasting land-atmosphere interactions. Different physical mechanisms drive precipitation recycling in each region. In the Midwestern United States, evapotranspiration is not significantly affected by soil moisture anomalies, and there is a high recycling ratio during periods of reduced total precipitation. The reason is that, during periods of drier atmospheric conditions, transpiration will continue to provide moisture to the overlying atmosphere and contribute to total rainfall. Consequently, precipitation recycling variability in not driven by changes in evapotranspiration. Precipitable water, sensible heat and moisture fluxes are the main drivers of recycling variability in the Midwest. However, the drier soil moisture conditions over the NAMS region limit evapotranspiration, which will drive recycling variability. In this region, evapotranspiration becomes an important contribution to precipitation after Monsoon onset when total precipitation and evapotranspiration are highest. The precipitation recycling process in the NAMS region relocates moisture from regions of high evapotranspiration like the seasonally dry tropical forests of Mexico to drier regions downwind. During long monsoons, when soil moisture is abundant for a prolonged period of time, precipitation recycling significantly contributes to precipitation during periods of reduced total rainfall. In both the moisture abundant Midwestern region and the drier NAMS region, precipitation recycling plays an important role in maintaining a favorable hydroclimatological environment for vegetation.

Absorbing Aerosols Workshop, January 20-21, 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nasiri, Shaima; Williamson, Ashley; Cappa, Christopher D.

2016-07-01

A workshop was held at DOE Headquarters on January 20-21, 2016 during which experts within and outside DOE were brought together to identify knowledge gaps in modeling and measurement of the contribution of absorbing aerosols (AA) to radiative forcing. Absorbing aerosols refer to those aerosols that absorb light, whereby they both reduce the amount of sunlight reaching the surface (direct effect) and heat their surroundings. By doing so, they modify the vertical distribution of heat in the atmosphere and affect atmospheric thermodynamics and stability, possibly hastening cloud drop evaporation, and thereby affecting cloud amount, formation, dissipation and, ultimately, precipitation. Depositionmore » of AA on snow and ice reduces surface albedo leading to accelerated melt. The most abundant AA type is black carbon (BC), which results from combustion of fossil fuel and biofuel. The other key AA types are brown carbon (BrC), which also results from combustion of fossil fuel and biofuel, and dust (crustal material). Each of these sources may result from, and be strongly influenced by, anthropogenic activities. The properties and amounts of AA depend upon various factors, primarily fuel source and burn conditions (e.g., internal combustion engine, flaming or smoldering wildfire), vegetation type (in the case of BC and BrC), and in the case of dust, soil type and ground cover (i.e., vegetation, snow, etc.). After emission, AA undergo chemical processing in the atmosphere that affects their physical and chemical properties. Thus, attribution of sources of AA, and understanding processes AA undergo during their atmospheric lifetimes, are necessary to understand how they will behave in a changing climate.« less

Ocean and atmosphere teleconnections modulate east tropical Pacific productivity at late to middle Pleistocene terminations

NASA Astrophysics Data System (ADS)

Diz, Paula; Hernández-Almeida, Iván; Bernárdez, Patricia; Pérez-Arlucea, Marta; Hall, Ian R.

2018-07-01

The modern Eastern Equatorial Pacific (EEP) is a key oceanographic region for regulating the Earth's climate system, accounting for between 5-10% of global marine production whilst also representing a major source of carbon dioxide efflux to the atmosphere. Changes in ocean dynamics linked to the nutrient supply from the Southern Ocean have been suggested to have played a dominant role in regulating EEP productivity over glacial-interglacial timescales of the past 500 ka. Yet, the full extent of the climate and oceanic teleconnections and the mechanisms promoting the observed increase of productivity occurring at glacial terminations remain poorly understood. Here we present multi-proxy, micropaleontological, geochemical and sedimentological records from the easternmost EEP to infer changes in atmospheric patterns and oceanic processes potentially influencing regional primary productivity over glacial-interglacial cycles of the mid-late Pleistocene (∼0-650 ka). These proxy data support a leading role for the north-south migration of the Intertropical Convergence Zone (ITCZ) in shaping past productivity variability in the EEP. Productivity increases during glacial periods and notably peaks at major and "extra" glacial terminations (those occurring 1-2 precession cycles after some major terminations) coincident with the inferred southernmost position of the ITCZ. The comparison of our reconstructions with proxy records of climate variability suggests the intensification of related extratropical atmospheric and oceanic teleconnections during deglaciation events. These processes may have re-activated the supply of southern sourced nutrients to the EEP, potentially contributing to enhanced productivity in the EEP and thus counterbalancing the oceanic carbon dioxide outgassing at glacial terminations.

[Relationship between atmospheric particles and rain water chemistry character].

PubMed

Huo, Ming-Qun; Sun, Qian; Xie, Peng; Bai, Yu-Hua; Liu, Zhao-Rong; Li, Ji-Long; Lu, Si-Hua

2009-11-01

Rain and atmospheric particle samples were collected in the rural area of Taian and Shenzhen in 2007, respectively. Rain sampling was carried out during the precipitation process and several samples were got from the beginning of one precipitation to the end. The chemical character changes during precipitation and the changes of concentration of particles before and after rain were studied in this research to understand the contribution of particles on the rain chemical character and the rain-out effect for particles. The volume-weighted mean pH of rainwater in Taian was 5.97 and the total concentration of ions was 1 187.96 microeq x L(-1). The mass concentration of PM10 in Taian was 131.76 microg/m3 and that of PM2.5 was 103.84 microg/m3. The volume-weighted mean pH of rainwater in Shenzhen was 4.72 and the total concentration of ions was 175.89 microeq x L(-1). The mass concentration of PM10 in Shenzhen was 56.66 microg/m3 and that of PM2.5 was 41.52 microg/m3. During precipitation process pH and ion concentration of rain decrease and it is shown the neutralizing effect happens. The difference between rainwater of Taian and Shenzhen is due to cloud water acidity, atmospheric particles character and atmospheric acid-basic gases concentration. The clean-up effect of Na+ and Ca2+ by rain is high and which of NH4+ and NO3- is low. The clean-up effect for mass concentration, ions concentration and element concentration of particles by rain are significant.

Modelling of plasma processes in cometary and planetary atmospheres

NASA Astrophysics Data System (ADS)

Campbell, L.; Brunger, M. J.

2013-02-01

Electrons from the Sun, often accelerated by magnetospheric processes, produce low-density plasmas in the upper atmospheres of planets and their satellites. The secondary electrons can produce further ionization, dissociation and excitation, leading to enhancement of chemical reactions and light emission. Similar processes are driven by photoelectrons produced by sunlight in upper atmospheres during daytime. Sunlight and solar electrons drive the same processes in the atmospheres of comets. Thus for both understanding of planetary atmospheres and in predicting emissions for comparison with remote observations it is necessary to simulate the processes that produce upper atmosphere plasmas. In this review, we describe relevant models and their applications and address the importance of electron-impact excitation cross sections, towards gaining a quantitative understanding of the phenomena in question.

A combined hydrochemical - isotopic approach for assessing the regional pollution of an alluvial aquifer in a urbanized environment

NASA Astrophysics Data System (ADS)

Gesels, Julie; Orban, Philippe; Popescu, Cristina; Knöller, Kay; Brouyère, Serge

2014-05-01

The alluvial aquifer of the Meuse River is contaminated at regional scale in the urbanized and industrialized area of Liège in Belgium with different types of contaminants, in particular inorganics such as sulfate, nitrate and ammonium. The sources of those contaminants are numerous: brownfields, urban waste water, subsurface acid mine drainage from former coal mines, atmospheric deposits related to pollutants emissions in the atmosphere... Sulfate, nitrate and ammonium are both typical pollutants of the aquifer and tracers of the possible pollution sources. According to the European legislation on water, groundwater resources should reach a good quality status before 2015. However, an exemption can be obtained if it may be unfeasible or unreasonably expensive to achieve good status. In this case, groundwater quality objectives and management plans can be adapted to these specific conditions. To obtain such an exemption for the Meuse alluvial aquifer, it is required to demonstrate that the poor qualitative status is caused by acid mine drainage, or by widespread historical atmospheric deposition from industries, and not by recent anthropogenic contamination from the urban and industrial context. In this context, a detailed hydrogeochemical characterization of groundwater has been performed, with the aim of determining the origin of the inorganic contaminations and the main processes contributing to poor groundwater quality. A large hydrochemical sampling campaign was performed, based on 71 selected representative sampling locations, to better characterize the different vectors (end-members) of contamination of the alluvial aquifer and their respective contribution to groundwater contamination in the area. Groundwater samples were collected and analyzed for major and minor compounds and metallic trace elements. The analyses also include stable isotopes in water, sulfate, nitrate, ammonium, boron and strontium. Different hydrogeochemical approaches are combined to obtain a global understanding of the hydrogeochemical processes at regional scale. Hydrochemical interpretations are based on classical diagrams (e.g. Piper), spatial distribution maps, geochemical equations, multivariate statistics and isotopic analyses. With this combined approach, the location of the contaminant sources and most contaminated sectors of the alluvial aquifer together with a better understanding of geochemical processes involved are obtained.

Processes of 30-90 days sea surface temperature variability in the northern Indian Ocean during boreal summer

NASA Astrophysics Data System (ADS)

Vialard, J.; Jayakumar, A.; Gnanaseelan, C.; Lengaigne, M.; Sengupta, D.; Goswami, B. N.

2012-05-01

During summer, the northern Indian Ocean exhibits significant atmospheric intraseasonal variability associated with active and break phases of the monsoon in the 30-90 days band. In this paper, we investigate mechanisms of the Sea Surface Temperature (SST) signature of this atmospheric variability, using a combination of observational datasets and Ocean General Circulation Model sensitivity experiments. In addition to the previously-reported intraseasonal SST signature in the Bay of Bengal, observations show clear SST signals in the Arabian Sea related to the active/break cycle of the monsoon. As the atmospheric intraseasonal oscillation moves northward, SST variations appear first at the southern tip of India (day 0), then in the Somali upwelling region (day 10), northern Bay of Bengal (day 19) and finally in the Oman upwelling region (day 23). The Bay of Bengal and Oman signals are most clearly associated with the monsoon active/break index, whereas the relationship with signals near Somali upwelling and the southern tip of India is weaker. In agreement with previous studies, we find that heat flux variations drive most of the intraseasonal SST variability in the Bay of Bengal, both in our model (regression coefficient, 0.9, against ~0.25 for wind stress) and in observations (0.8 regression coefficient); ~60% of the heat flux variation is due do shortwave radiation and ~40% due to latent heat flux. On the other hand, both observations and model results indicate a prominent role of dynamical oceanic processes in the Arabian Sea. Wind-stress variations force about 70-100% of SST intraseasonal variations in the Arabian Sea, through modulation of oceanic processes (entrainment, mixing, Ekman pumping, lateral advection). Our ~100 km resolution model suggests that internal oceanic variability (i.e. eddies) contributes substantially to intraseasonal variability at small-scale in the Somali upwelling region, but does not contribute to large-scale intraseasonal SST variability due to its small spatial scale and random phase relation to the active-break monsoon cycle. The effect of oceanic eddies; however, remains to be explored at a higher spatial resolution.

Sources of fine organic aerosol. 2. Noncatalyst and catalyst-equipped automobiles and heavy-duty diesel trucks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogge, W.F.; Hildemann, L.M.; Mazurek, M.A.

Gasoline- and diesel-powered vehicles are known to contribute appreciable amounts of inhalable fine particulate matter to the atmosphere in urban areas. Internal combustion engines burning gasoline and diesel fuel contribute more than 21% of the primary fine particulate organic carbon emitted to the Los Angeles atmosphere. In the present study, particulate (d[sub p] [le] 2 [mu]m) exhaust emissions from six noncatalyst automobiles, seven catalyst-equipped automobiles, and two heavy-duty diesel trucks are examined by gas chromatography/mass spectrometry. The purposes of this study are as follows: (a) to search for conservative marker compounds suitable for tracing the presence of vehicular particulate exhaustmore » emissions in the urban atmosphere, (b) to compile quantitative source profiles, and (c) to study the contributions of fine organic particulate vehicular exhaust to the Los Angeles atmosphere. More than 100 organic compounds are quantified, including n-alkanes, n-alkanoic acids, benzoic acids, benzaldehydes, PAH, oxy-PAH, steranes, pentacyclic triterpanes, azanaphthalenes, and others. Although fossil fuel markers such as steranes and pentacyclic triterpanes can be emitted from other sources, it can be shown that their ambient concentrations measured in the Los Angeles atmosphere are attributable mainly to vehicular exhaust emissions. 102 refs., 9 figs., 6 tabs.« less

Contribution of Infrasound to IDC Reviewed Event Bulletin

NASA Astrophysics Data System (ADS)

Bittner, Paulina; Polich, Paul; Gore, Jane; Ali, Sherif Mohamed; Medinskaya, Tatiana; Mialle, Pierrick

2016-04-01

Until 2003 two waveform technologies, i.e. seismic and hydroacoustic were used to detect and locate events included in the International Data Centre (IDC) Reviewed Event Bulletin (REB). The first atmospheric event was published in the REB in 2003 but infrasound detections could not be used by the Global Association (GA) Software due to the unmanageable high number of spurious associations. Offline improvements of the automatic processing took place to reduce the number of false detections to a reasonable level. In February 2010 the infrasound technology was reintroduced to the IDC operations and has contributed to both automatic and reviewed IDC bulletins. The primary contribution of infrasound technology is to detect atmospheric events. These events may also be observed at seismic stations, which will significantly improve event location. Examples of REB events, which were detected by the International Monitoring System (IMS) infrasound network were fireballs (e.g. Bangkok fireball, 2015), volcanic eruptions (e.g. Calbuco, Chile 2015) and large surface explosions (e.g. Tjanjin, China 2015). Query blasts and large earthquakes belong to events primarily recorded at seismic stations of the IMS network but often detected at the infrasound stations. Presence of infrasound detection associated to an event from a mining area indicates a surface explosion. Satellite imaging and a database of active mines can be used to confirm the origin of such events. This presentation will summarize the contribution of 6 years of infrasound data to IDC bulletins and provide examples of events recorded at the IMS infrasound network. Results of this study may help to improve location of small events with observations on infrasound stations.

The role of impacting processes in the chemical evolution of the atmosphere of primordial Earth

NASA Technical Reports Server (NTRS)

Mukhin, Lev M.; Gerasimov, M. V.

1991-01-01

The role of impacting processes in the chemical evolution of the atmosphere of primordial Earth is discussed. The following subject areas are covered: (1) Earth's initial atmosphere; (2) continuous degassing; (3) impact processes and the Earth's protoatmosphere; and (4) the evolution of an impact-generated atmosphere.

Infragravity waves in the ocean as a source of acoustic-gravity waves in the atmosphere

NASA Astrophysics Data System (ADS)

Zabotin, Nikolay A.; Godin, Oleg A.

2013-04-01

Infragravity waves (IGWs) are surface gravity waves in the ocean with periods longer than the longest periods (~30s) of wind-generated waves. IGWs propagate transoceanic distances with very little attenuation in deep water and, because of their long wavelengths (from ~1 km to hundreds of km), provide a mechanism for coupling wave processes in the ocean, ice shelves, the atmosphere, and the solid Earth. Here, we build on recent advances in understanding spectral and spatial variability of background infragravity waves in deep ocean to evaluate the IGW manifestations in the atmosphere. Water compressibility has a minor effect on IGWs. On the contrary, much larger compressibility and vertical extent of the atmosphere makes it necessary to treat IGW extension into the atmosphere as acoustic-gravity waves. There exist two distinct regimes of IGW penetration into the atmosphere. At higher frequencies, one has surface waves in the atmosphere propagating horizontally along the ocean surface and prominent up to heights of the order of the wavelength. At lower frequencies, IGWs are leaky waves, which continuously radiate their energy into the upper atmosphere. The transition between the two regimes occurs at a frequency of the order of 3 mHz, with the exact value of the transition frequency being a function of the ocean depth, the direction of IGW propagation and the vertical profiles of temperature and wind velocity. The transition frequency decreases with increasing ocean depth. Using recently obtained semi-empirical model of power spectra the IGWs over varying bathymetry [Godin O. A., Zabotin N. A., Sheehan A. F., Yang Z., and Collins J. A. Power spectra of infragravity waves in a deep ocean, Geophys. Res. Lett., under review (2012)], we derive an estimate of the flux of the mechanical energy from the deep ocean into the atmosphere due to IGWs. Significance will be discussed of the IGW contributions into the field of acoustic-gravity waves in the atmosphere.

In-Situ Atmospheric Sounding Data Lifecycle from Data Collection, Analysis and Quality Control to Documentation, Archival and Tracking

NASA Astrophysics Data System (ADS)

Young, K.; Voemel, H.; Morris, D.

2015-12-01

In-situ measurement systems are used to monitor the atmosphere whereby instruments are located in the area of interest and are in direct contact with what is being measured. Dropsondes and radiosondes are instruments used to collect high-vertical-resolution profiles of the atmosphere. The dropsondes are deployed from aircraft and, as they descend, they collect pressure, temperature and humidity data at a half-second rate, and GPS wind data at a quarter-second rate. Radiosondes are used to collect high-resolution measurements of the atmosphere, from the ground to approximately 30 kilometers. Carried by a large helium-filled balloon, they ascend upward through the atmosphere measuring pressure, temperature, relative humidity, and GPS winds at a one-second rate. Advancements in atmospheric research, technology and data assimilation techniques have contributed to driving the need for higher quality, higher resolution radiosonde and dropsonde data at an increasingly rapid rate. These data most notably represent a valuable resource for initializing numerical prediction models, calibrating and validating satellite retrieval techniques for atmospheric profiles, and for climatological research. The In-Situ Sensing Facility, at NCAR, has developed an extensive, multi-step process of quality control (QC). Traditionally, QC has been a time intensive process that involves evaluating data products using a variety of visualization tools and statistical methods. With a greater need for real-time data in the field and a reduced turn-around time for final quality controlled data, new and improved procedures for streamlining statistical analysis and QC are being implemented. Improvements have also been made on two fronts regarding implementation of a comprehensive data management plan. The first was ensuring ease of data accessibility through an intuitive centralized data archive system, that both keeps a record of data users and assigns digital object identifiers to each unique data set. The second improvement was to define appropriate criteria needed for documentation and metadata so that data users have all of the relevant information needed to properly use and understand the complexities of these measurements.

Late Veneer consequences on Venus' long term evolution

NASA Astrophysics Data System (ADS)

Gillmann, C.; Golabek, G.; Tackley, P. J.; Raymond, S. N.

2017-12-01

Modelling of Venus' evolution is able to produce scenarios consistent with present-day observation. These results are however heavily dependent on atmosphere escape and initial volatile inventory. This primordial history (the first 500 Myr) is heavily influenced by collisions. We investigate how Late Veneer impacts change the initial state of Venus and their consequences on its coupled mantle/atmosphere evolution. We focus on volatile fluxes: atmospheric escape and mantle degassing. Mantle dynamics is simulated using the StagYY code. Atmosphere escape covers both thermal and non-thermal processes. Surface conditions are calculated with a radiative-convective model. Feedback of the atmosphere on the mantle through surface temperature is included. Large impacts are capable of contributing to atmospheric escape, volatile replenishment and energy transfer. We use the SOVA hydrocode to take into account volatile loss and deposition during a collision. Large impacts are not numerous enough to substantially erode Venus' atmosphere. Single impacts don't have enough eroding power. Swarms of small bodies (<50km radius) might be a better candidate for this process. The amount of volatiles brought by large ordinary chondrite impactors is superior to losses and comparable to the degassing caused by the impact. Carbonaceous chondrite impactors are unlikely: they release too many volatiles, causing surface temperature to stay above 900K up to present-day. Mantle dynamics can also be modified by the heating caused by impacts. Heated material propagates by spreading across the upper mantle due to its buoyancy. Old crust is destroyed or remixed in the mantle. A large part of the upper mantle melts, leading to its depletion and degassing. With enough evenly distributed high energy impacts, the mantle can be depleted by more than 90% of its volatiles during Late Veneer. This drastically cuts down degassing in the late history of the planet and leads to lower present-day surface temperatures. Total depletion of the mantle seems unlikely, meaning either few large impacts (1 to 4) or low energy (slow, grazing…) collisions. Combined with the lack of plate tectonics and volatile recycling in the interior of Venus, Late Veneer collisions could help explain why Venus seems dry today.

Atmospheric Emissions from Forest Biomass Residues to Energy Supply Chain: A Case Study in Portugal.

PubMed

Rafael, Sandra; Tarelho, Luis; Monteiro, Alexandra; Monteiro, Tânia; Gonçalves, Catarina; Freitas, Sylvio; Lopes, Myriam

2015-06-01

During the past decades, pressures on global environment and energy security have led to an increasing demand on renewable energy sources and diversification of the world's energy supply. The Portuguese energy strategy considers the use of Forest Biomass Residues (FBR) to energy as being essential to accomplish the goals established in the National Energy Strategy for 2020. However, despite the advantages pointing to FBR to the energy supply chain, few studies have evaluated the potential impacts on air quality. In this context, a case study was selected to estimate the atmospheric emissions of the FBR to the energy supply chain in Portugal. Results revealed that production, harvesting, and energy conversion processes are the main culprits for the biomass energy supply chain emissions (with a contribution higher than 90%), while the transport processes have a minor importance for all the pollutants. Compared with the coal-fired plants, the FBR combustion produces lower greenhouses emissions, on a mass basis of fuel consumed; the same is true for NO X and SO 2 emissions.

The Sample Analysis at Mars Investigation and Instrument Suite

NASA Technical Reports Server (NTRS)

Mahaffy, Paul; Webster, Christopher R.; Conrad, Pamela G.; Arvey, Robert; Bleacher, Lora; Brinckerhoff, William B.; Eigenbrode, Jennifer L.; Chalmers, Robert A.; Dworkin, Jason P.; Errigo, Therese;

Interactive Vegetation Phenology, Soil Moisture, and Monthly Temperature Forecasts

NASA Technical Reports Server (NTRS)

Koster, R. D.; Walker, G. K.

2015-01-01

The time scales that characterize the variations of vegetation phenology are generally much longer than those that characterize atmospheric processes. The explicit modeling of phenological processes in an atmospheric forecast system thus has the potential to provide skill to subseasonal or seasonal forecasts. We examine this possibility here using a forecast system fitted with a dynamic vegetation phenology model. We perform three experiments, each consisting of 128 independent warm-season monthly forecasts: 1) an experiment in which both soil moisture states and carbon states (e.g., those determining leaf area index) are initialized realistically, 2) an experiment in which the carbon states are prescribed to climatology throughout the forecasts, and 3) an experiment in which both the carbon and soil moisture states are prescribed to climatology throughout the forecasts. Evaluating the monthly forecasts of air temperature in each ensemble against observations, as well as quantifying the inherent predictability of temperature within each ensemble, shows that dynamic phenology can indeed contribute positively to subseasonal forecasts, though only to a small extent, with an impact dwarfed by that of soil moisture.

Atmospheric Emissions from Forest Biomass Residues to Energy Supply Chain: A Case Study in Portugal

PubMed Central

Rafael, Sandra; Tarelho, Luis; Monteiro, Alexandra; Monteiro, Tânia; Gonçalves, Catarina; Freitas, Sylvio; Lopes, Myriam

2015-01-01

Abstract During the past decades, pressures on global environment and energy security have led to an increasing demand on renewable energy sources and diversification of the world's energy supply. The Portuguese energy strategy considers the use of Forest Biomass Residues (FBR) to energy as being essential to accomplish the goals established in the National Energy Strategy for 2020. However, despite the advantages pointing to FBR to the energy supply chain, few studies have evaluated the potential impacts on air quality. In this context, a case study was selected to estimate the atmospheric emissions of the FBR to the energy supply chain in Portugal. Results revealed that production, harvesting, and energy conversion processes are the main culprits for the biomass energy supply chain emissions (with a contribution higher than 90%), while the transport processes have a minor importance for all the pollutants. Compared with the coal-fired plants, the FBR combustion produces lower greenhouses emissions, on a mass basis of fuel consumed; the same is true for NOX and SO2 emissions. PMID:26064039

Chemical and Physical Interactions of Martian Surface Material

NASA Astrophysics Data System (ADS)

Bishop, J. L.

1999-09-01

A model of alteration and maturation of the Martian surface material is described involving both chemical and physical interactions. Physical processes involve distribution and mixing of the fine-grained soil particles across the surface and into the atmosphere. Chemical processes include reaction of sulfate, salt and oxidizing components of the soil particles; these agents in the soils deposited on rocks will chew through the rock minerals forming coatings and will bind surface soils together to form duricrust deposits. Formation of crystalline iron oxide/oxyhydroxide minerals through hydrothermal processes and of poorly crystalline and amorphous phases through palagonitic processes both contribute to formation of the soil particles. Chemical and physical alteration of these soil minerals and phases contribute to producing the chemical, magnetic and spectroscopic character of the Martian soil as observed by Mars Pathfinder and Mars Global Surveyor. Minerals such as maghemite/magnetite and jarosite/alunite have been observed in terrestrial volcanic soils near steam vents and may be important components of the Martian surface material. The spectroscopic properties of several terrestrial volcanic soils containing these minerals have been analyzed and evaluated in terms of the spectroscopic character of the surface material on Mars.

Decomposing Shortwave Top-of-Atmosphere Radiative Flux Variability in Terms of Surface and Atmospheric Contributions Using CERES Observations

NASA Astrophysics Data System (ADS)

Loeb, N. G.; Wong, T.; Wang, H.

2017-12-01

Earth's climate is determined by the exchange of radiant energy between the Sun, Earth and space. The absorbed solar radiation (ASR) fuels the climate system, providing the energy required for atmospheric and oceanic motions, while the system cools by emitting outgoing longwave (LW) radiation to space. A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget along with the associated atmospheric and surface properties that influence it. CERES data products utilize a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, polar orbiting and geostationary spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. Here we use simple diagnostic model of Earth's albedo and CERES Energy Balanced and Filled (EBAF) Ed4.0 data for March 2000-February 2016 to quantify interannual variations in SW TOA flux associated with surface albedo and atmospheric reflectance and transmittance variations. Surface albedo variations account for <0.5% of the total SW TOA flux variance over the tropics and 4% globally. Variations in atmospheric reflectance and transmittance account for virtually all of the total SW TOA flux variance over the tropics and only 81% globally. The remaining 15% of the global SW TOA flux variance is explained by the co-variance of surface albedo and atmospheric reflectance/transmittance. Equatorward of 60-degree latitude, the atmospheric contribution exceeds that of the surface by at least an order-of-magnitude. In contrast, the surface and atmospheric variations contribute equally poleward of 60S and surface variations account for twice as much as the atmosphere poleward of 60N. However, as much as 40% of the total SW TOA flux variance poleward of 60N is explained by the covariance of surface albedo and atmospheric reflectance/transmittance, highlighting the tight coupling between sea-ice concentration and cloud properties over the Arctic Ocean.

A search for optical evidence for lightning on Venus with VIRTIS on Venus Express

NASA Astrophysics Data System (ADS)

Abildgaard, Sofie; Cardesin, Alejandro; Garcia Múnoz, Antonio; Piccioni, Giuseppe

2015-04-01

Lightning is known to occur on the atmospheres of Earth, Jupiter, Saturn, Uranus and Neptune, but although the occurrence of lightning in the Venusian atmosphere has been published several times in the past years, always on the basis of detected electromagnetic pulses, the subject is still controversial. It is generally agreed that an optical observation of the phenomenon would settle the issue. In this work we analyse the data collection of hyper-spectral images produced by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) on Venus Express, that has been observing the Venusian atmosphere continuously since 2006. A dedicated search algorithm for transient events was developed and a detailed analysis of the archive was performed in all wavelengths. The first preliminary analysis have been performed and we have proven that transient events can easily be identified in the data. Work is ongoing for optimizing search parameters and performing a statistical analysis. In this contribution, we will present a summary of the data analysis process and some of the preliminary conclusion in the lightning detection/nondetection.

Biomass burning a driver for global change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levine, J.S.; Cofer, W.R. III; Cahoon, D.R. Jr.

1995-03-01

Recent research has identified another biospheric process that has instantaneous and longer term effects on the production of atmospheric gases: biomass burning. Biomass burning includes the burning of the world`s vegetation-forests, savannas. and agricultural lands, to clear the land and change its use. Only in the past decade have researchers realized the important contributions of biomass burning to the global budgets of many radiatively and chemically active gases - carbon dioxide, methane, nitric oxide, tropospheric ozone, methyl chloride - and elemental carbon particulates. International field experiments and satellite data are yielding a clearer understanding of this important global source ofmore » atmospheric gases and particulates. It is seen that in addition to being a significant instantaneous global source of atmospheric gases and particulates, burning enhances the biogenic emissions of nitric oxide and nitrous oxide from the world`s soils. Biomass burning affects the reflectivity and emissivity of the Earth`s surface as well as the hydrological cycle by changing rates of land evaporation and water runoff. For these reasons, it appears that biomass burning is a significant driver of global change. 20 refs., 4 figs., 2 tabs.« less

Radiative Cooling: Principles, Progress, and Potentials

PubMed Central

Hossain, Md. Muntasir

2016-01-01

The recent progress on radiative cooling reveals its potential for applications in highly efficient passive cooling. This approach utilizes the maximized emission of infrared thermal radiation through the atmospheric window for releasing heat and minimized absorption of incoming atmospheric radiation. These simultaneous processes can lead to a device temperature substantially below the ambient temperature. Although the application of radiative cooling for nighttime cooling was demonstrated a few decades ago, significant cooling under direct sunlight has been achieved only recently, indicating its potential as a practical passive cooler during the day. In this article, the basic principles of radiative cooling and its performance characteristics for nonradiative contributions, solar radiation, and atmospheric conditions are discussed. The recent advancements over the traditional approaches and their material and structural characteristics are outlined. The key characteristics of the thermal radiators and solar reflectors of the current state‐of‐the‐art radiative coolers are evaluated and their benchmarks are remarked for the peak cooling ability. The scopes for further improvements on radiative cooling efficiency for optimized device characteristics are also theoretically estimated. PMID:27812478

Sources of Infrasound events listed in IDC Reviewed Event Bulletin

NASA Astrophysics Data System (ADS)

Bittner, Paulina; Polich, Paul; Gore, Jane; Ali, Sherif; Medinskaya, Tatiana; Mialle, Pierrick

2017-04-01

Until 2003 two waveform technologies, i.e. seismic and hydroacoustic were used to detect and locate events included in the International Data Centre (IDC) Reviewed Event Bulletin (REB). The first atmospheric event was published in the REB in 2003, however automatic processing required significant improvements to reduce the number of false events. In the beginning of 2010 the infrasound technology was reintroduced to the IDC operations and has contributed to both automatic and reviewed IDC bulletins. The primary contribution of infrasound technology is to detect atmospheric events. These events may also be observed at seismic stations, which will significantly improve event location. Examples sources of REB events, which were detected by the International Monitoring System (IMS) infrasound network were fireballs (e.g. Bangkok fireball, 2015), volcanic eruptions (e.g. Calbuco, Chile 2015) and large surface explosions (e.g. Tjanjin, China 2015). Query blasts (e.g. Zheleznogorsk) and large earthquakes (e.g. Italy 2016) belong to events primarily recorded at seismic stations of the IMS network but often detected at the infrasound stations. In case of earthquakes analysis of infrasound signals may help to estimate the area affected by ground vibration. Infrasound associations to query blast events may help to obtain better source location. The role of IDC analysts is to verify and improve location of events detected by the automatic system and to add events which were missed in the automatic process. Open source materials may help to identify nature of some events. Well recorded examples may be added to the Reference Infrasound Event Database to help in analysis process. This presentation will provide examples of events generated by different sources which were included in the IDC bulletins.

Volatiles on Mars

NASA Astrophysics Data System (ADS)

Jakosky, Bruce M.

1988-08-01

The long-term evolution of both the atmosphere and the surface of Mars can be understood by examining the history of volatiles in the Mars atmosphere, their non-atmospheric reservoirs, and the processes of exchange between the two. Clearly, the present state of both the surface and the atmosphere can only be seen, so that any inferences about the evolution of the climate system are just that, inferences. The processes which control the atmosphere and surface on a seasonal basis, however, are the same processes which can act on longer timescales; only the specific solar and atmospheric forcing will differ. Once the ability of each process to affect the seasonal behavior is understood, the long-timescale forcing may be applied to the various processes in order to clearly identify the ability of the processes to act over the entire history of Mars. The areas of surface-atmospheric interaction of Mars are addressed in the ongoing research. The climate system on Mars is controlled by processes involving the exchange between the surface and atmosphere, so it is important to understand the current behavior of those processes. This is especially so in light of the current interest in understanding Mars; the upcoming Mars Observer mission, and the potential for a future sample-return or human-exploration mission will focus emphasis on this area of Mars science.

Measuring the Contribution of Atmospheric Scatter to Laser Eye Dazzle

DTIC Science & Technology

2015-09-01

alignment of the detector was then fine tuned to ensure that the reflected beam traveled perfectly back through the aperture, thus indicating normal...spanning June and July 2014. A narrow acceptance angle detector was used to measure scattered laser radiation within the laser beam at different... scatter does not make a significant contribution to laser eye dazzle for short-range laser engagements in atmospheres of good to moderate air quality

Energy Industry Study, AY 2004-2005

DTIC Science & Technology

2005-06-01

produced by burning coal and other fossil fuels contributes to the greenhouse effect by trapping the sun’s heat in the atmosphere and eventually causing... greenhouse effect by trapping the sun’s heat in the atmosphere and eventually causing major changes in the world’s climate. Third, the coal industry faces...possibly human health. Second, many scientists believe that carbon dioxide produced by burning coal and other fossil fuels contributes to the

Contribution of Brown Carbon to Direct Radiative Forcing over the Indo-Gangetic Plain.

PubMed

Shamjad, P M; Tripathi, S N; Pathak, Ravi; Hallquist, M; Arola, Antti; Bergin, M H

2015-09-01

The Indo-Gangetic Plain is a region of known high aerosol loading with substantial amounts of carbonaceous aerosols from a variety of sources, often dominated by biomass burning. Although black carbon has been shown to play an important role in the absorption of solar energy and hence direct radiative forcing (DRF), little is known regarding the influence of light absorbing brown carbon (BrC) on the radiative balance in the region. With this in mind, a study was conducted for a one month period during the winter-spring season of 2013 in Kanpur, India that measured aerosol chemical and physical properties that were used to estimate the sources of carbonaceous aerosols, as well as parameters necessary to estimate direct forcing by aerosols and the contribution of BrC absorption to the atmospheric energy balance. Positive matrix factorization analyses, based on aerosol mass spectrometer measurements, resolved organic carbon into four factors including low-volatile oxygenated organic aerosols, semivolatile oxygenated organic aerosols, biomass burning, and hydrocarbon like organic aerosols. Three-wavelength absorption and scattering coefficient measurements from a Photo Acoustic Soot Spectrometer were used to estimate aerosol optical properties and estimate the relative contribution of BrC to atmospheric absorption. Mean ± standard deviation values of short-wave cloud free clear sky DRF exerted by total aerosols at the top of atmosphere, surface and within the atmospheric column are -6.1 ± 3.2, -31.6 ± 11, and 25.5 ± 10.2 W/m(2), respectively. During days dominated by biomass burning the absorption of solar energy by aerosols within the atmosphere increased by ∼35%, accompanied by a 25% increase in negative surface DRF. DRF at the top of atmosphere during biomass burning days decreased in negative magnitude by several W/m(2) due to enhanced atmospheric absorption by biomass aerosols, including BrC. The contribution of BrC to atmospheric absorption is estimated to range from on average 2.6 W/m(2) for typical ambient conditions to 3.6 W/m(2) during biomass burning days. This suggests that BrC accounts for 10-15% of the total aerosol absorption in the atmosphere, indicating that BrC likely plays an important role in surface and boundary temperature as well as climate.

Transport of Chemical Vapors from Subsurface Sources to Atmosphere as Affected by Shallow Subsurface and Atmospheric Conditions

NASA Astrophysics Data System (ADS)

Rice, A. K.; Smits, K. M.; Hosken, K.; Schulte, P.; Illangasekare, T. H.

2012-12-01

Understanding the movement and modeling of chemical vapor through unsaturated soil in the shallow subsurface when subjected to natural atmospheric thermal and mass flux boundary conditions at the land surface is of importance to applications such as landmine detection and vapor intrusion into subsurface structures. New, advanced technologies exist to sense chemical signatures at the land/atmosphere interface, but interpretation of these sensor signals to make assessment of source conditions remains a challenge. Chemical signatures are subject to numerous interactions while migrating through the unsaturated soil environment, attenuating signal strength and masking contaminant source conditions. The dominant process governing movement of gases through porous media is often assumed to be Fickian diffusion through the air phase with minimal or no quantification of other processes contributing to vapor migration, such as thermal diffusion, convective gas flow due to the displacement of air, expansion/contraction of air due to temperature changes, temporal and spatial variations of soil moisture and fluctuations in atmospheric pressure. Soil water evaporation and interfacial mass transfer add to the complexity of the system. The goal of this work is to perform controlled experiments under transient conditions of soil moisture, temperature and wind at the land/atmosphere interface and use the resulting dataset to test existing theories on subsurface gas flow and iterate between numerical modeling efforts and experimental data. Ultimately, we aim to update conceptual models of shallow subsurface vapor transport to include conditionally significant transport processes and inform placement of mobile sensors and/or networks. We have developed a two-dimensional tank apparatus equipped with a network of sensors and a flow-through head space for simulation of the atmospheric interface. A detailed matrix of realistic atmospheric boundary conditions was applied in a series of experiments. Water saturation, capillary pressure, air and soil temperature, and relative humidity were continuously monitored. Aqueous TCE was injected into the tank below the water table and allowed to volatilize. TCE concentration exiting the tank head space was measured through interval sampling by direct injection into a gas chromatograph. To quantify the transient concentration of TCE vapor in the soil pore space a novel use of Solid Phase Micro-Extraction (SPME) was developed. Results from our numerical simulations were compared with the experimental data, which demonstrated the importance of considering the interaction of the atmosphere with the subsurface in conceptualization and numerical model development. Results also emphasize that soil saturation and transient sorption have a significant effect on vapor transport through the vadose zone. Follow-up tests and detailed analyses are still underway. Additional applications of this work include carbon sequestration leakage, methane contamination in the shallow subsurface and environmental impact of hydraulic fracturing.

The Effect of CO2 Ice Cap Sublimation on Mars Atmosphere

NASA Technical Reports Server (NTRS)

Batterson, Courtney

2016-01-01

Sublimation of the polar CO2 ice caps on Mars is an ongoing phenomenon that may be contributing to secular climate change on Mars. The transfer of CO2 between the surface and atmosphere via sublimation and deposition may alter atmospheric mass such that net atmospheric mass is increasing despite seasonal variations in CO2 transfer. My study builds on previous studies by Kahre and Haberle that analyze and compare data from the Phoenix and Viking Landers 1 and 2 to determine whether secular climate change is happening on Mars. In this project, I use two years worth of temperature, pressure, and elevation data from the MSL Curiosity rover to create a program that allows for successful comparison of Curiosity pressure data to Viking Lander pressure data so a conclusion can be drawn regarding whether CO2 ice cap sublimation is causing a net increase in atmospheric mass and is thus contributing to secular climate change on Mars.

Multiple greenhouse-gas feedbacks from the land biosphere under future climate change scenarios

NASA Astrophysics Data System (ADS)

Stocker, Benjamin D.; Roth, Raphael; Joos, Fortunat; Spahni, Renato; Steinacher, Marco; Zaehle, Soenke; Bouwman, Lex; Xu-Ri; Prentice, Iain Colin

2013-07-01

Atmospheric concentrations of the three important greenhouse gases (GHGs) CO2, CH4 and N2O are mediated by processes in the terrestrial biosphere that are sensitive to climate and CO2. This leads to feedbacks between climate and land and has contributed to the sharp rise in atmospheric GHG concentrations since pre-industrial times. Here, we apply a process-based model to reproduce the historical atmospheric N2O and CH4 budgets within their uncertainties and apply future scenarios for climate, land-use change and reactive nitrogen (Nr) inputs to investigate future GHG emissions and their feedbacks with climate in a consistent and comprehensive framework. Results suggest that in a business-as-usual scenario, terrestrial N2O and CH4 emissions increase by 80 and 45%, respectively, and the land becomes a net source of C by AD 2100. N2O and CH4 feedbacks imply an additional warming of 0.4-0.5°C by AD 2300; on top of 0.8-1.0°C caused by terrestrial carbon cycle and Albedo feedbacks. The land biosphere represents an increasingly positive feedback to anthropogenic climate change and amplifies equilibrium climate sensitivity by 22-27%. Strong mitigation limits the increase of terrestrial GHG emissions and prevents the land biosphere from acting as an increasingly strong amplifier to anthropogenic climate change.

Partly cloudy with a chance of migration: Weather, radars, and aeroecology

USGS Publications Warehouse

Chilson, Phillip B.; Frick, Winifred F.; Kelly, Jeffrey F.; Howard, Kenneth W.; Larkin, Ronald P.; Diehl, Robert H.; Westbrook, John K.; Kelly, T. Adam; Kunz, Thomas H.

2012-01-01

Aeroecology is an emerging scientific discipline that integrates atmospheric science, Earth science, geography, ecology, computer science, computational biology, and engineering to further the understanding of biological patterns and processes. The unifying concept underlying this new transdisciplinary field of study is a focus on the planetary boundary layer and lower free atmosphere (i.e., the aerosphere), and the diversity of airborne organisms that inhabit and depend on the aerosphere for their existence. Here, we focus on the role of radars and radar networks in aeroecological studies. Radar systems scanning the atmosphere are primarily used to monitor weather conditions and track the location and movements of aircraft. However, radar echoes regularly contain signals from other sources, such as airborne birds, bats, and arthropods. We briefly discuss how radar observations can be and have been used to study a variety of airborne organisms and examine some of the many potential benefits likely to arise from radar aeroecology for meteorological and biological research over a wide range of spatial and temporal scales. Radar systems are becoming increasingly sophisticated with the advent of innovative signal processing and dual-polarimetric capabilities. These capabilities should be better harnessed to promote both meteorological and aeroecological research and to explore the interface between these two broad disciplines. We strongly encourage close collaboration among meteorologists, radar scientists, biologists, and others toward developing radar products that will contribute to a better understanding of airborne fauna.

Role of meteorological processes in two New England ozone episodes during summer 2001

NASA Astrophysics Data System (ADS)

Mao, Huiting; Talbot, Robert

2004-10-01

We examined the impact of dynamical processes on spatial variability in ozone (O3) mixing ratios at closely spaced air monitoring sites in southern New Hampshire (NH) during two O3 episodes, July 21-25 and August 2, 2001. The Meso-scale Meteorological Model (MM5) and the Community Multiscale Air Quality (CMAQ) photochemical model were applied together with ground-based atmospheric chemistry observations conducted by the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) program at the University of New Hampshire. Observations and model simulations suggested that during the July episode long-range transport via the nocturnal low-level jet (LLJ) played an important role in producing elevated daytime mixing ratios of O3. The marine site Isle of Shoals experienced the highest level of O3, possibly a result of having more diverse upwind sources and less ventilation compared to continental sites. Our model results suggest that during daytime the shallow sea breeze circulation contributes to high levels of O3 at coastal and marine sites while the channeling effect of the Appalachian Mountains influences inland locations. In contrast to the July event, the event on August 2 was characterized by weak and transient synoptic flows, indicating insufficient time for transport of O3 and its precursors from distant sources to inland sites in NH. Backward trajectories for both events showed that O3-rich air masses from the Boston metropolitan area can contribute to the high levels of O3 (>120 ppbv) at coastal and marine sites in southern NH. Our results suggest that the International Consortium of Atmospheric Research on Transport and Transformation (ICARTT), an international field campaign based in the northeastern United States in summer 2004, should coordinate mobile platforms to investigate the vertical structure and chemical composition of the LLJ, the sea breeze, and the terrain-forced flows, and estimate the influx of O3 and its precursors to central New England.

Contribution of tropical instability waves to ENSO irregularity

NASA Astrophysics Data System (ADS)

Holmes, Ryan M.; McGregor, Shayne; Santoso, Agus; England, Matthew H.

2018-05-01

Tropical instability waves (TIWs) are a major source of internally-generated oceanic variability in the equatorial Pacific Ocean. These non-linear phenomena play an important role in the sea surface temperature (SST) budget in a region critical for low-frequency modes of variability such as the El Niño-Southern Oscillation (ENSO). However, the direct contribution of TIW-driven stochastic variability to ENSO has received little attention. Here, we investigate the influence of TIWs on ENSO using a 1/4° ocean model coupled to a simple atmosphere. The use of a simple atmosphere removes complex intrinsic atmospheric variability while allowing the dominant mode of air-sea coupling to be represented as a statistical relationship between SST and wind stress anomalies. Using this hybrid coupled model, we perform a suite of coupled ensemble forecast experiments initiated with wind bursts in the western Pacific, where individual ensemble members differ only due to internal oceanic variability. We find that TIWs can induce a spread in the forecast amplitude of the Niño 3 SST anomaly 6-months after a given sequence of WWBs of approximately ± 45% the size of the ensemble mean anomaly. Further, when various estimates of stochastic atmospheric forcing are added, oceanic internal variability is found to contribute between about 20% and 70% of the ensemble forecast spread, with the remainder attributable to the atmospheric variability. While the oceanic contribution to ENSO stochastic forcing requires further quantification beyond the idealized approach used here, our results nevertheless suggest that TIWs may impact ENSO irregularity and predictability. This has implications for ENSO representation in low-resolution coupled models.

Updating the conceptual model for fine particle mass emissions from combustion systems.

PubMed

Robinson, Allen L; Grieshop, Andrew P; Donahue, Neil M; Hunt, Sherri W

2010-10-01

Atmospheric transformations determine the contribution of emissions from combustion systems to fine particulate matter (PM) mass. For example, combustion systems emit vapors that condense onto existing particles or form new particles as the emissions are cooled and diluted. Upon entering the atmosphere, emissions are exposed to atmospheric oxidants and sunlight, which causes them to evolve chemically and physically, generating secondary PM. This review discusses these transformations, focusing on organic PM. Organic PM emissions are semi-volatile at atmospheric conditions and thus their partitioning varies continuously with changing temperature and concentration. Because organics contribute a large portion of the PM mass emitted by most combustion sources, these emissions cannot be represented using a traditional, static emission factor. Instead, knowledge of the volatility distribution of emissions is required to explicitly account for changes in gas-particle partitioning. This requires updating how PM emissions from combustion systems are measured and simulated from combustion systems. Secondary PM production often greatly exceeds the direct or primary PM emissions; therefore, secondary PM must be included in any assessment of the contribution of combustion systems to ambient PM concentrations. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary PM precursors that are poorly accounted for in inventories and models. The review concludes by discussing the implications that the dynamic nature of these PM emissions have on source testing for emission inventory development and regulatory purposes. This discussion highlights important linkages between primary and secondary PM, which could lead to simplified certification test procedures while capturing the emission components that contribute most to atmospheric PM mass.

Updating the Conceptual Model for Fine Particle Mass Emissions from Combustion Systems Allen L. Robinson.

PubMed

Robinson, Allen L; Grieshop, Andrew P; Donahue, Neil M; Hunt, Sherri W

2010-10-01

Atmospheric transformations determine the contribution of emissions from combustion systems to fine particulate matter (PM) mass. For example, combustion systems emit vapors that condense onto existing particles or form new particles as the emissions are cooled and diluted. Upon entering the atmosphere, emissions are exposed to atmospheric oxidants and sunlight, which causes them to evolve chemically and physically, generating secondary PM. This review discusses these transformations, focusing on organic PM. Organic PM emissions are semi -volatile at atmospheric conditions and thus their partitioning varies continuously with changing temperature and concentration. Because organics contribute a large portion of the PM mass emitted by most combustion sources, these emissions cannot be represented using a traditional, static emission factor. Instead, knowledge of the volatility distribution of emissions is required to explicitly account for changes in gas-particle partitioning. This requires updating how PM emissions from combustion systems are measured and simulated from combustion systems. Secondary PM production often greatly exceeds the direct or primary PM emissions; therefore, secondary PM must be included in any assessment of the contribution of combustion systems to ambient PM concentrations. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary PM precursors that are poorly accounted for in inventories and models. The review concludes by discussing the implications that the dynamic nature of these PM emissions have on source testing for emission inventory development and regulatory purposes. This discussion highlights important linkages between primary and secondary PM, which could lead to simplified certification test procedures while capturing the emission components that contribute most to atmospheric PM mass.

Wildland fire emissions, carbon, and climate: Plume rise, atmospheric transport, and chemistry processes

Treesearch

Warren Heilman; Yongqiang Liu; Shawn Urbanski; Vladimir Kovalev; Robert Mickler

2014-01-01

This paper provides an overview and summary of the current state of knowledge regarding critical atmospheric processes that affect the distribution and concentrations of greenhouse gases and aerosols emitted from wildland fires or produced through subsequent chemical reactions in the atmosphere. These critical atmospheric processes include the dynamics of plume rise,...

Optimized method for atmospheric signal reduction in irregular sampled InSAR time series assisted by external atmospheric information

NASA Astrophysics Data System (ADS)

Gong, W.; Meyer, F. J.

2013-12-01

It is well known that spatio-temporal the tropospheric phase signatures complicate the interpretation and detection of smaller magnitude deformation signals or unstudied motion fields. Several advanced time-series InSAR techniques were developed in the last decade that make assumptions about the stochastic properties of the signal components in interferometric phases to reduce atmospheric delay effects on surface deformation estimates. However, their need for large datasets to successfully separate the different phase contributions limits their performance if data is scarce and irregularly sampled. Limited SAR data coverage is true for many areas affected by geophysical deformation. This is either due to their low priority in mission programming, unfavorable ground coverage condition, or turbulent seasonal weather effects. In this paper, we present new adaptive atmospheric phase filtering algorithms that are specifically designed to reconstruct surface deformation signals from atmosphere-affected and irregularly sampled InSAR time series. The filters take advantage of auxiliary atmospheric delay information that is extracted from various sources, e.g. atmospheric weather models. They are embedded into a model-free Persistent Scatterer Interferometry (PSI) approach that was selected to accommodate non-linear deformation patterns that are often observed near volcanoes and earthquake zones. Two types of adaptive phase filters were developed that operate in the time dimension and separate atmosphere from deformation based on their different temporal correlation properties. Both filter types use the fact that atmospheric models can reliably predict the spatial statistics and signal power of atmospheric phase delay fields in order to automatically optimize the filter's shape parameters. In essence, both filter types will attempt to maximize the linear correlation between a-priori and the extracted atmospheric phase information. Topography-related phase components, orbit errors and the master atmospheric delays are first removed in a pre-processing step before the atmospheric filters are applied. The first adaptive filter type is using a filter kernel of Gaussian shape and is adaptively adjusting the width (defined in days) of this filter until the correlation of extracted and modeled atmospheric signal power is maximized. If atmospheric properties vary along the time series, this approach will lead to filter setting that are adapted to best reproduce atmospheric conditions at a certain observation epoch. Despite the superior performance of this first filter design, its Gaussian shape imposes non-physical relative weights onto acquisitions that ignore the known atmospheric noise in the data. Hence, in our second approach we are using atmospheric a-priori information to adaptively define the full shape of the atmospheric filter. For this process, we use a so-called normalized convolution (NC) approach that is often used in image reconstruction. Several NC designs will be presented in this paper and studied for relative performance. A cross-validation of all developed algorithms was done using both synthetic and real data. This validation showed designed filters are outperforming conventional filter methods that particularly useful for regions with limited data coverage or lack of a deformation field prior.

Solar energy demand (SED) of commodity life cycles.

PubMed

Rugani, Benedetto; Huijbregts, Mark A J; Mutel, Christopher; Bastianoni, Simone; Hellweg, Stefanie

2011-06-15

The solar energy demand (SED) of the extraction of 232 atmospheric, biotic, fossil, land, metal, mineral, nuclear, and water resources was quantified and compared with other energy- and exergy-based indicators. SED represents the direct and indirect solar energy required by a product or service during its life cycle. SED scores were calculated for 3865 processes, as implemented in the Ecoinvent database, version 2.1. The results showed that nonrenewable resources, and in particular minerals, formed the dominant contribution to SED. This large share is due to the indirect solar energy required to produce these resource inputs. Compared with other energy- and exergy-based indicators, SED assigns higher impact factors to minerals and metals and smaller impact factors to fossil energetic resources, land use, and nuclear energy. The highest differences were observed for biobased and renewable energy generation processes, whose relative contribution of renewable resources such as water, biomass, and land occupation was much lower in SED than in energy- and exergy-based indicators.

Enhanced transfer of terrestrially derived carbon to the atmosphere in a flooding event

USGS Publications Warehouse

Bianchi, Thomas S.; Garcia-Tigreros, Fenix; Yvon-Lewis, Shari A.; Shields, Michael; Mills, Heath J.; Butman, David; Osburn, Christopher; Raymond, Peter A.; Shank, G. Christopher; DiMarco, Steven F.; Walker, Nan; Kiel Reese, Brandi; Mullins-Perry, Ruth; Quigg, Antonietta; Aiken, George R.; Grossman, Ethan L.

2013-01-01

Rising CO2 concentration in the atmosphere, global climate change, and the sustainability of the Earth's biosphere are great societal concerns for the 21st century. Global climate change has, in part, resulted in a higher frequency of flooding events, which allow for greater exchange between soil/plant litter and aquatic carbon pools. Here we demonstrate that the summer 2011 flood in the Mississippi River basin, caused by extreme precipitation events, resulted in a “flushing” of terrestrially derived dissolved organic carbon (TDOC) to the northern Gulf of Mexico. Data from the lower Atchafalaya and Mississippi rivers showed that the DOC flux to the northern Gulf of Mexico during this flood was significantly higher than in previous years. We also show that consumption of radiocarbon-modern TDOC by bacteria in floodwaters in the lower Atchafalaya River and along the adjacent shelf contributed to northern Gulf shelf waters changing from a net sink to a net source of CO2 to the atmosphere in June and August 2011. This work shows that enhanced flooding, which may or may not be caused by climate change, can result in rapid losses of stored carbon in soils to the atmosphere via processes in aquatic ecosystems.

Zhamanshin astrobleme provides evidence for carbonaceous chondrite and post-impact exchange between ejecta and Earth's atmosphere.

PubMed

Magna, Tomáš; Žák, Karel; Pack, Andreas; Moynier, Frédéric; Mougel, Bérengère; Peters, Stefan; Skála, Roman; Jonášová, Šárka; Mizera, Jiří; Řanda, Zdeněk

2017-08-09

Chemical fingerprints of impacts are usually compromised by extreme conditions in the impact plume, and the contribution of projectile matter to impactites does not often exceed a fraction of per cent. Here we use chromium and oxygen isotopes to identify the impactor and impact-plume processes for Zhamanshin astrobleme, Kazakhstan. ε 54 Cr values up to 1.54 in irghizites, part of the fallback ejecta, represent the 54 Cr-rich extremity of the Solar System range and suggest a CI-like chondrite impactor. Δ 17 O values as low as -0.22‰ in irghizites, however, are incompatible with a CI-like impactor. We suggest that the observed 17 O depletion in irghizites relative to the terrestrial range is caused by partial isotope exchange with atmospheric oxygen (Δ 17 O = -0.47‰) following material ejection. In contrast, combined Δ 17 O-ε 54 Cr data for central European tektites (distal ejecta) fall into the terrestrial range and neither impactor fingerprint nor oxygen isotope exchange with the atmosphere are indicated.Identifying the original impactor from craters remains challenging. Here, the authors use chromium and oxygen isotopes to indicate that the Zhamanshin astrobleme impactor was a carbonaceous chrondrite by demonstrating that depleted 17O values are due to exchange with atmospheric oxygen.