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1

Utility of soil linear alkylbenzenes to assess regional anthropogenic influences with special reference to atmospheric transport.  

PubMed

Tracing regional anthropogenic influences is important for assessing the magnitude of human interferences with the environment. In the present study, the utility of soil linear alkylbenzenes (LABs) as indicators of anthropogenic influences was examined, with the emphasis on the role of atmospheric transport in dissipating LABs from input sources to remote areas. The Pearl River Delta, South China, which has experienced rapid economic growth and urbanization, was selected as the study region. The concentrations of LABs (mean: 8.6 ng/g and median: 5.7 ng/g, with an outlier of 2,020 ng/g excluded) suggested that sewage contamination throughout the entire study region was generally light. The spatial variation of sewage pollution was significantly positively correlated with population density and per capita gross domestic product, with hot spots concentrated in the central PRD. Atmospheric deposition was hypothesized as an important input route for soil LABs in forestry and drinking water source areas with little impact of irrigation or direct wastewater discharge. This proposition could explain the opposite spatial patterns of LAB concentrations and values of a biodegradation index (5-C12+5-C13)/(5-C11+5-C10), where i-Cn defines a specific LAB congener with i and n indicating the position of the phenyl group and the number of carbon atoms on the alkyl chain, respectively. These findings somewhat validated LABs as tracers of regional anthropogenically derived contamination, with atmospheric transport of LABs as a viable dissipating mechanism. PMID:24813768

Wei, Gao-Ling; Bao, Lian-Jun; Guo, Ling-Chuan; He, Zai-Cheng; Wu, Feng-Chang; Zeng, Eddy Y

2014-07-15

2

Influence of Uncertainty in Atmospheric Transport Modeling on Regional and Continental Scale Inversions  

NASA Astrophysics Data System (ADS)

Atmospheric transport modeling and its uncertainty play a crucial role in inversion studies with a goal to estimate fluxes of trace gases like carbon dioxide from available concentration measurements. Lagrangian particle models (e.g., CSU LPDM, STILT, FLEXPART) driven by regional meteorological models (e.g., WRF, RAMS) are state of the art tools in regional CO2 research including not only inversion studies, but also designing of tower network, or testing and supporting flight scenarios. They are typically used backward in time as an adjoint transport model providing, for each data point, influence functions (footprints) for surface fluxes and inflow fluxes across a domain perimeter. Modeling system used at CSU is based on SiB-RAMS (Regional Atmospheric Modeling System with Simple Biosphere model) providing meteorological fields for the LPDM (Lagrangian Particle Dispersion Model). Our LPDM can be run both in a forward and backward in time mode. Therefore, we recommend to use the comparison of forward and backward in time simulations as a method to evaluate internal model uncertainty. In addition the LPDM concentration fields can be compared to tracer concentrations simulated directly by RAMS, i.e. Eulerian grid model. We will discuss how simulated concentration fields, and in turn, the results of atmospheric inversions are affected by (1) model simplifications and optimizations, (2) time and space resolution of meteorological fields, and (3) selection of a domain for inversion study. The simulations are performed for the North America and smaller regional domains for a passive tracer and a tracers resulting from different CO2 fluxes (assimilation and respiration). Finally, we would like to propose a framework for inter comparison of different LPDMs coupled to regional meteorological models. This framework includes a sparse matrix format for influence functions to facilitate exchange and further applications of this product by different research groups.

Uliasz, M.; Schuh, A. E.

2011-12-01

3

Influence of sea-land breezes on the tempospatial distribution of atmospheric aerosols over coastal region.  

PubMed

The influence of sea-land breezes (SLBs) on the spatial distribution and temporal variation of particulate matter (PM) in the atmosphere was investigated over coastal Taiwan. PM was simultaneously sampled at inland and offshore locations during three intensive sampling periods. The intensive PM sampling protocol was continuously conducted over a 48-hr period. During this time, PM2.5 and PM(2.5-10) (PM with aerodynamic diameters < 2.5 microm and between 2.5 and 10 microm, respectively) were simultaneously measured with dichotomous samplers at four sites (two inland and two offshore sites) and PM10 (PM with aerodynamic diameters < or =10 microm) was measured with beta-ray monitors at these same 4 sites and at 10 sites of the Taiwan Air Quality Monitoring Network. PM sampling on a mobile air quality monitoring boat was further conducted along the coastline to collect offshore PM using a beta-ray monitor and a dichotomous sampler. Data obtained from the inland sites (n=12) and offshore sites (n=2) were applied to plot the PM10 concentration contour using Surfer software. This study also used a three-dimensional meteorological model (Pennsylvania State University/National Center for Atmospheric Research Meteorological Model 5) and the Comprehensive Air Quality Model with Extensions to simulate surface wind fields and spatial distribution of PM10 over the coastal region during the intensive sampling periods. Spatial distribution of PM10 concentration was further used in investigating the influence of SLBs on the transport of PM10 over the coastal region. Field measurement and model simulation results showed that PM10 was transported back and forth across the coastline. In particular, a high PM10 concentration was observed at the inland sites during the day because of sea breezes, whereas a high PM10 concentration was detected offshore at night because of land breezes. This study revealed that the accumulation of PM in the near-ocean region because of SLBs influenced the tempospatial distribution of PM10 over the coastal region. PMID:21516932

Tsai, Hsieh-Hung; Yuan, Chung-Shin; Hung, Chung-Hsuang; Lin, Chitsan; Lin, Yuan-Chung

2011-04-01

4

Vegetation Influence on Regional Climate Change: A 3D Integrated Atmospheric-Surface-Subsurface Analysis  

NASA Astrophysics Data System (ADS)

Human induced land-use change has been shown to be one of the major contributing factors to anthropogenic regional climate change. The transition from densely vegetated forests with deep root zones to shallow rooted agricultural ecosystems drastically limits the natural buffering capacity of deep groundwater during severe drought conditions. In order to quantify the magnitude of climate change from altered ecosystems, we employed the 3D model HydroGeoSphere, an integrated variably-saturated subsurface/surface flow and heat transport model, coupled with a simplified zero-dimensional atmospheric boundary layer model to simulate an extended seasonal drought period. It is found that during drought conditions, trees with deep root zones are capable of maintaining higher evapotranspiration rates, higher latent heat fluxes, and a damped atmospheric temperature response. In contrast, grasses with shallow root zones have minimal evapotranspiration rates, lower latent heat fluxes, and a rapid and sharp atmospheric temperature response. On the whole, converting a naturally wooded ecosystem to a farmland or pasture effectively decreases the available water in the subsurface for transpiration subsequently amplifying the atmospheric response to severe weather.

Davison, J. H.; Hwang, H.; Sudicky, E. A.; Lin, J. C.

2013-12-01

5

Atmospheric circulation in regional climate models over Central Europe: links to surface air temperature and the influence of driving data  

NASA Astrophysics Data System (ADS)

We examine simulation of atmospheric circulation and links between circulation and daily surface air temperatures in current climate models over Central Europe. Large-scale atmospheric circulation is represented by circulation indices (flow direction, strength and vorticity) derived from mean sea level pressure. We explore control simulations of five 25-km resolution RCMs from the ENSEMBLES project, driven by the ERA-40 re-analysis and the ECHAM5 GCM, and runs of one RCM (RCA) driven by different GCMs. The driving GCMs are investigated as well. The models' performance is compared against the dataset gridded from a high-density stations network (temperature) and the ERA-40 re-analysis (pressure). The aims of the study are (i) to identify errors in simulated distributions of circulation indices in individual seasons, (ii) to identify errors in simulated temperatures under particular circulation indices in winter and summer, and (iii) to compare performance of individual RCMs with respect to the driving data. We find that most of the RCMs qualitatively reflect observed distributions of the airflow indices; however, each produces distributions significantly different from the observations. General biases include overestimation of the frequency of strong cyclonic vorticity and of strong flow days. HIRHAM driven by ECHAM5 and RCA driven by BCM are the RCMs with the most distorted atmospheric circulation. Our results show that some circulation biases obviously propagate from the driving data. For example, ECHAM5 and all simulations driven by ECHAM5 underestimate frequency of easterly flow. However, except for HIRHAM, all RCMs driven by ECHAM5 improve on the driving GCM in simulating atmospheric circulation. A set of RCA simulations with different driving data demonstrates that the influence on circulation characteristics in the nested RCM differs between GCMs. We find relatively strong relationships between circulation indices and surface air temperatures in the observed data for Central Europe. The RCMs qualitatively reproduce these relationships, which differ by season and are usually stronger for daily maxima than minima. Our results suggest that the RCM formulation appears to be more important than the driving data in representing the links to surface temperature. Differences of the circulation-to-temperature links among the RCA simulations are smaller and the links tend to be more realistic compared to the driving GCMs. Plavcová E., Kyselý J., 2012: Atmospheric circulation in regional climate models over Central Europe: links to surface air temperature and the influence of driving data. Climate Dynamics [10.1007/s00382-011-1278-8.

Plavcová, E.; Kyselý, J.

2012-04-01

6

Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO sub 2 and Climate Change --- The MINK Project  

SciTech Connect

The second report of a series Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project is composed of two parts. This Report (IIB) deals with agriculture at the level of farms and Major Land Resource Areas (MLRAs). The Erosion Productivity Impact Calculator (EPIC), a crop growth simulation model developed by scientists at the US Department of Agriculture, is used to study the impacts of the analog climate on yields of main crops in both the 1984/87 and the 2030 baselines. The results of this work with EPIC are the basis for the analysis of the climate change impacts on agriculture at the region-wide level undertaken in this report. Report IIA treats agriculture in MINK in terms of state and region-wide production and resource use for the main crops and animals in the baseline periods of 1984/87 and 2030. The effects of the analog climate on the industry at this level of aggregation are considered in both baseline periods. 41 refs., 40 figs., 46 tabs.

Easterling, W.E. III; McKenney, M.S.; Rosenberg, N.J.; Lemon, K.M.

1991-08-01

7

The effect of regional-scale soil-moisture deficits on mesoscale atmospheric dynamics that influence fire severity  

SciTech Connect

This study employs a three-dimensional, nonhydrostatic mesoscale model to evaluate the effects of horizontally heterogeneous soil moisture and vegetation type on the atmosphere during two periods in which wildland fires occurred. Numerical sensitivity simulations demonstrate that evapotranspiration significantly affects the boundary-layer structure embedded in the synoptic-scale circulations. In regions with sufficiently moist soils, evapotranspiration increases the humidity and modifies the diurnally varying temperature near the surface. Occasionally, changes in the humidity and temperature fields can also be seen a significant distance downwind of the moist soil regions. The perturbations in the temperature fields ultimately affect the wind speed and direction over or at the boundaries of the moist-soil regions, but only at certain times during the simulation period. The higher humidity also increases the cloudiness and changes the precipitation amounts, indicating that soil moisture and vegetation may play an important role in modifying the spatial distribution and intensity of precipitation. A lower atmospheric stability index, that is an indicator of the potential for wildland fire, is also calculated from the model results. This index is also sensitive to the horizontal distribution of soil moisture and vegetation, especially in regions with relatively moist soils. While only two periods are examined in this study, the impact of surface inhomogeneities in soil moisture and vegetation type on the atmosphere is expected to be highly dependent on the particular synoptic conditions and upon the distribution of soil moisture.

Fast, J.D.

1994-09-30

8

How the Atmosphere Influences Aridity  

NSDL National Science Digital Library

This site, produced by the U.S. Geological Survey, describes the circulation pattern of Earth's atmosphere, which is influenced by differential heating and the Coriolis Effect. This circulation causes the formation of warm, dry areas on the Earth's surface which are where deserts are likely to exist. The site features text, a photograph, and a scientific illustration showing the atmospheric circulation pattern.

9

On the influence of atmospheric chemical reactions on the ion composition of aerosol particles in the Baikal region  

NASA Astrophysics Data System (ADS)

Monitoring data on the ion composition of aerosols and gas admixtures in the background and polluted atmosphere of the Lake Baikal region are presented. The ion composition and morphology of aerosols are affected by heterogeneous chemical reactions and variations in relative humidity. Two types of aerosol particles are revealed over this region. The fraction of solid particles recorded in most episodes includes primarily carbonates of alkaline and alkaline-earth metals. With increased atmospheric humidity, these particles are engaged in heterogeneous chemical reactions with gas-phase NH3 and H2SO4, proceeding through the phase of watering. As a result, the composition of these aerosols is changed, and a fraction of aqueous H2O/H2SO4/(NH4)2SO4 aerosol particles of a different composition is formed. On the basis of a physical and chemical analysis of monitoring data on the aerosol composition and concentrations of gas admixtures, the average aerosol-size distribution of different types is estimated. For the first time, the mean acidity of aqueous aerosol particles is estimated.

Yermakov, A. N.; Aloyan, A. E.; Khodzer, T. V.; Golobokova, L. P.; Arutyunyan, V. O.

2007-04-01

10

Indonesian peat and vegetation fire emissions: Study on factors influencing large-scale smoke haze pollution using a regional atmospheric chemistry model  

Microsoft Academic Search

Numerical modelling of fire-related smoke haze episodes in Southeast Asia is important for both prediction and assessment\\u000a of atmospheric impacts, especially when observational data are fragmentary, as is the case in Indonesia. This work describes\\u000a the atmospheric fate of smoke particles emitted during the 1997 Indonesian fires modelled with a regional atmospheric chemistry\\u000a model. We established a new fire emission

A. Heil; B. Langmann; E. Aldrian

2007-01-01

11

Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets  

SciTech Connect

Inversions of atmospheric CO2 mixing ratio measurements to determine CO2 sources and sinks are typically limited to coarse spatial and temporal resolution. This limits our ability to evaluate efforts to upscale chamber- and stand-level CO2 flux measurements to regional scales, where coherent climate and ecosystem mechanisms govern the carbon cycle. As a step towards the goal of implementing atmospheric budget or inversion methodology on a regional scale, a network of five relatively inexpensive CO2 mixing ratio measurement systems was deployed on towers in northern Wisconsin. Four systems were distributed on a circle of roughly 150-km radius, surrounding one centrally located system at the WLEF tower near Park Falls, WI. All measurements were taken at a height of 76 m AGL. The systems used single-cell infrared CO2 analyzers (Licor, model LI-820) rather than the siginificantly more costly two-cell models, and were calibrated every two hours using four samples known to within ± 0.2 ppm CO2. Tests prior to deployment in which the systems sampled the same air indicate the precision of the systems to be better than ± 0.3 ppm and the accuracy, based on the difference between the daily mean of one system and a co-located NOAA-ESRL system, is consistently better than ± 0.3 ppm. We demonstrate the utility of the network in two ways. We interpret regional CO2 differences using a Lagrangian parcel approach. The difference in the CO2 mixing ratios across the network is at least 2?3 ppm, which is large compared to the accuracy and precision of the systems. Fluxes estimated assuming Lagrangian parcel transport are of the same sign and magnitude as eddy-covariance flux measurements at the centrally-located WLEF tower. These results indicate that the network will be useful in a full inversion model. Second, we present a case study involving a frontal passage through the region. The progression of a front across the network is evident; changes as large as four ppm in one minute are captured. Influence functions, derived using a Lagrangian Particle Dispersion model driven by the CSU Regional Atmospheric Modeling System and nudged to NCEP reanalysis meteorological fields, are used to determine source regions for the towers. The influence functions are combined with satellite vegetation observations to interpret the observed trends in CO2 concentration. Full inversions will combine these elements in a more formal analytic framework.

Davis, K.J.; Richardson, S.J.; Miles, N.L.

2007-03-07

12

Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets  

Microsoft Academic Search

Inversions of atmospheric CO2 mixing ratio measurements to determine CO2 sources and sinks are typically limited to coarse spatial and temporal resolution. This limits our ability to evaluate efforts to upscale chamber- and stand-level CO2 flux measurements to regional scales, where coherent climate and ecosystem mechanisms govern the carbon cycle. As a step towards the goal of implementing atmospheric budget

K. J. Davis; S. J. Richardson; N. L. Miles

2007-01-01

13

A Regional Modeling Study of the Influence of Urban Land Cover Change on the Lower Atmosphere in Baltimore-Washington DC  

NASA Astrophysics Data System (ADS)

The land-use and land cover (LULC) history of the Baltimore-Washington region has been intensively studied through a variety of environmental research collaborations and regional partnerships. One such partnership, the Baltimore-Washington Regional Collaboratory, involved multiple Federal and local agencies cooperating on a 200-year urban growth study in the Chesapeake region. Information from this study on pre-1900 and current LULC conditions for the Baltimore-Washington DC area was integrated with data from other sources to construct different lower boundary conditions for a series of simulations using the Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS). We use the RAMS simulations to diagnose the extent and nature of the effect of urban anomalies in surface heat, moisture, and momentum on mid-summer local and regional climate. The experimental design adopted for this study takes advantage of the grid-nesting capability of RAMS. A fine grid with 1km horizontal resolution was nested into a coarser 5 km grid, which extends from southern Pennsylvania, Maryland, to parts of Virginia, and West Virginia. Two sets of month-long simulations for July 2000 were conducted with RAMS running in parallel on a 26-processor cluster of computers at the Cooperative Institute for Research in the Atmosphere (CIRA), CSU. In the first set of simulations, we initially used satellite-derived current land cover data as the lower boundary condition in a 31-day RAMS run. We then replaced this data with the pre-1900 land cover data for the same region and ran a similar RAMS simulation. Identical observed meteorology was retained for the lateral boundary conditions in both cases. The model results for the initial run were validated with July 2000 surface climate data and flux measurements of sensible and latent heat from sites located within the fine grid model domain. Additional simulations were conducted to compare RAMS model performance using prescribed land surface conditions with results from a physically based scheme for urban energy budget coupled to RAMS. The urban surface scheme used here is the Town Energy Budget (TEB) model recently developed at the Center for Meteorological Research (CNRM), France. The TEB model allows for a refinement of model computed radiative budgets, heat and momentum based on a generalization of the classic canyon approach. Results from both sets of simulations, and the implications, for surface climate, of the driving human-induced land cover transformations are discussed.

Adegoke, J.; Gallo, K.; Pielke, R.; Rozoff, C.; Steyaert, L.

2001-12-01

14

Processes for identifying regional influences of and responses to increasing atmospheric CO{sub 2} and climate change - the MINK project: An overview  

SciTech Connect

Scientists believe that a serious change in the climate of the earth could occur in the course of the next two to five decades as a result of warming caused by the rapid accumulation of radiatively active trace gases in the atmosphere. There is concern that not only the amount of warming but the rate at which it occurs could be unprecedented, at least since the current interglacial period began. Scientific uncertainties remain in our understanding of the climatic changes that may follow from greenhouse warming. Nevertheless, large and rapid changes in regional climate are conceivable. General circulation models (GCMs) predict changes for the central U.S. as large as an 8{degrees}C increase in mean summertime temperature accompanied by a 1 mm/day decrease in mean precipitation. Most predictions are less extreme but, so long as the direction of change is credible, efforts are warranted to identify just what kinds of impacts to expect if society chooses to allow climate to change or cannot stop it from changing, and just what might be done to adjust to those impacts.

Rosenberg, N.J.; Crosson, P.R. [Resources for the Future, Washington, DC (United States)

1991-08-01

15

Moon influence on equatorial atmospheric angular momentum  

NASA Astrophysics Data System (ADS)

The variation of the equatorial atmospheric angular momentum function, coordinated with respect to a star-fixed system, is investigated in relation with the lunar tide. We isolate the rapid fluctuations, below 30 days, where Moon motion has a possible influence. First we notice that pressure term and wind term are almost proportional, by contrast to celestial seasonal band (S1). This would mean that, in this frequency band, the torque of the atmosphere on the solid Earth mostly results from the equatorial bulge. Spectrum reveals sharp lunar tidal peaks at 13.66 days (O1 diurnal tide in the terrestrial frame) and 13.63 days, reflecting the Moon influence on meridional circulation. We also observe powerful episodic fluctuations between 5 and 8 days (up to 10 mas), possibly resulting from non linear effect of the O1 tide, or tidal waves 2Q1 (6.86 days) and ?1 (7.095 days).

Bizouard, Christian; Zotov, Leonid; Sidorenkov, Nikolay

2014-05-01

16

Possible Solar Influence On Atmospheric Electric Field  

E-print Network

A cell dynamical system model for the troposphere - ionosphere coupling is proposed . Vertical mass exchange in the troposphere-ionosphere-magnetosphere takes place through a chain of eddy systems. Any perturbation in the troposphere would be transmitted to ionosphere and vice versa. A global perturbation in ionosphere, as the one caused by solar variability, is transmitted to troposphere influencing weather systems/geomagnetic/atmospheric electrification processes.

Poonam Sikka; A. Mary Selvam; A. S. Ramachandra Murty; Bh. V. Ramana Murty

1998-06-12

17

Atmospheric chemistry - Response to human influence  

NASA Technical Reports Server (NTRS)

Global atmospheric chemistry is surveyed, and the agreement of models with observed distribution of gases is considered. The influence of human perturbations due to combustion, agriculture, and chloro-carbon releases is examined with emphasis on ozone. Effects of combustion-related releases of CO on the abundances of other gases as well as possible effects of CO on tropospheric ozone are discussed. Other topics include the contribution of the chlorocarbon industry to stratospheric chloride and the recombination of nitrogen fixed by agriculture and combustion.

Logan, J. A.; Prather, M. J.; Wofsy, S. G.; Mcelroy, M. B.

1978-01-01

18

Influence of CO on Titan atmospheric reactivity  

NASA Astrophysics Data System (ADS)

The atmosphere of Titan is mainly composed of N2 and CH4 which are the source of various CxHyNz photochemical volatiles products. Laboratory simulations of the Titan’s atmospheric reactivity were mainly interested in the study of the complex organic chemistry which leads to the formation of analogues of Titan’s aerosols, called tholins. These studies were mainly interested in the reactivity of the N2/CH4 gaseous mixture and with the primary products of reactions without oxygen. However, the atmosphere of Titan also contains oxygenated volatile species. The most abundant one to have been detected is CO with a concentration about 50 ppmv. The work presented here is an experimental simulation devoted to estimate the influence of CO on the Titan’s atmospheric reactivity. With this aim, CO is introduced in a standard N2/CH4 mixture at different mixing ratio up to 4.5%. The kinetics of the methane consumption is monitored with in situ mass spectrometry and the compositions of the gaseous phase and tholins produced in the reactor are characterized ex situ with GC-MS and elemental analysis. This work shows that CO modifies the composition of the gas phase with the detection of oxygenated compounds: CO2 and N2O. The presence of CO also drastically decreases the production rate of tholins, involving also a perturbation on the methane kinetics. Tholins are produced in lower global amounts, but their sizes are found to be significantly larger than without CO. The oxygen incorporation in tholins is found to be efficient, with an oxygen content of the same order of magnitude as the amount of CO in the initial gas mixture.

Fleury, B.; Carrasco, N.; Gautier, T.; Mahjoub, A.; He, J.; Szopa, C.; Hadamcik, E.; Buch, A.; Cernogora, G.

2014-08-01

19

New atmospheric composition observations in the Karakorum region: Influence of local emissions and large-scale circulation during a summer field campaign  

NASA Astrophysics Data System (ADS)

In this work we provide an overview of short lived climate forcers (SLCFs) and carbon dioxide variability in the Karakorum, by presenting results deriving from a field campaign carried out at Askole (3015 m a.s.l., Pakistan Northern Areas), by Baltoro glacier. By using an innovative embedded and transportable system, continuous measurements of aerosol particle number concentration (Np, 1571 ± 2670 cm-3), surface ozone (O3, 31.7 ± 10.4 nmol/mol), carbon dioxide (CO2, 394.3 ± 6.9 ?mol/mol) and meteorological parameters have been performed from August 20th to November 10th 2012. The domestic combustion from the Askole village emerged as a possible systematic source of contamination in the valley, with short-lasting pollution events probably related to domestic cooking activities characterized by high values of Np (6066 ± 5903 cm-3). By excluding these local contamination events, mountain thermal wind regime dominated the diurnal variability of Np, O3 and CO2. In comparison to night-time, we observed higher Np (+354 cm-3) and O3 (+7 nmol/mol) but lower CO2 (-8 ?mol/mol) in air-masses coming from the lower valley during the central part of the day. Part of the day-to-day atmospheric composition variability can be also ascribed to synoptic circulation variability, as observed by using HYSPLIT 5-day back-trajectories.

Putero, D.; Cristofanelli, P.; Laj, P.; Marinoni, A.; Villani, P.; Broquet, A.; Alborghetti, M.; Bonafè, U.; Calzolari, F.; Duchi, R.; Landi, T. C.; Verza, G. P.; Vuillermoz, E.; Bonasoni, P.

2014-11-01

20

Wet and Dry Regions in Jupiter's Atmosphere  

NASA Technical Reports Server (NTRS)

Models of Jupiter's formation and interior predict that its atmosphere is enriched in oxygen relative to the Sun and that consequently, a water cloud is present globally near the 5-bar pressure level.

Carlson, R.; Roos-Serote, M.; Vasarada, A.; Kamp, L.; Drossart, P.; Irwin, P.; Nixon, C.

2000-01-01

21

Atmospheric tracer experiments for regional dispersion studies  

SciTech Connect

Tracer experiments are being conducted to verify atmospheric transport and dispersion calculations at distances from tens to hundreds of km from pollutant sources. In one study, a 2 1/2 year sampling program has been carried out at 13 sites located 30 to 140 km from a source of /sup 85/Kr at the Savannah River Plant in South Carolina. Average weekly concentrations as well as twice-daily concentrations were obtained. Sampling data and meteorological data, including surface, tower, and rawinsonde observations are available on magnetic tape for model verification studies. Some verification results for the Air Resources Laboratories Atmospheric Transort and Dispersion Model (ARL-ATAD) are shown for averaging periods from one week to two years.

Heffter, J.L.; Ferber, G.J.

1980-01-01

22

ATMOSPHERI[C CHEMISTRY: RESPONSE T O HUMAN INFLUENCE  

E-print Network

ATMOSPHERI[C CHEMISTRY: RESPONSE T O HUMAN INFLUENCE BYJ E N N I F E R A. LOGAN, M. J. PRATHER trace gases. The abundances of many shorter lived species are also satisfactorily reproduced, including and their significance assessed. The influence of human perturbations due to combustion, agriculture and chloro- carbon

Jacob, Daniel J.

23

Biogenic influence on cloud microphysics in the 'clean' oceanic atmosphere  

NASA Astrophysics Data System (ADS)

A 20 years old hypothesis postulates a feedback relationship between marine biota and climate through the emission of dimethylsulfide (DMS) as the principal natural source of Sulfate Secondary Aerosols (S-DMS) that are very efficient as cloud condensation nuclei (CCN). In recent years, the biological influence on cloud microphysics have been expanded to other potential biogenic cloud precursors: (i) volatile organic compounds produced by plankton and emitted to the atmosphere to form Secondary Organic Aerosols (SOA); (ii) biological particles and biogenic polymers, lifted with the seaspray by wind friction and bubble-bursting processes, that act as Primary Organic Aerosols (POA). Besides these biogenic aerosols, also seaspray-associated Sea Salt (SS) emissions, which are the dominant contribution to aerosol mass in the remote mixed boundary layer, also contribute to cloud condensation. All these aerosols affect cloud microphysics by providing new CCN, reducing the size of cloud droplets, and increasing cloud albedo. We have compared the seasonalities of the parameterized source functions of these natural cloud precursors with that of the satellite-derived cloud droplet effective radius (CLEFRA) over large regions of the ocean. Regions where big loads of continental aerosols (including anthropogenic -industrial, urban, and biomass burning) dominate during a significant part of the year were identified by use of remote sensing aerosol optical properties and excluded from our analysis. Our results show that the seasonality of cloud droplet effective radius matches those of S-DMS and SOA in the clean marine atmosphere, whereas SS and chlorophyll-associated POA on their own do not seem to play a major role in driving cloud droplet size.

Lana, A.; Simó, R.; Vallina, S. M.; Jurado, E.; Dachs, J.

2009-12-01

24

TES Regional and Global Atmospheric Chemistry Data Available From the NASA Langley Atmospheric Science Data Center  

Microsoft Academic Search

TES Regional and Global Atmospheric Chemistry Data Available from the NASA Langley Atmospheric Science Data Center The Tropospheric Emission Spectrometer (TES) was launched into a sun-synchronous orbit aboard Aura, the third of NASA's Earth Observing System spacecraft, on July 15, 2004. The primary objective of TES is to make global, three-dimensional measurements of ozone and other chemical species involved in

L. A. Hunt

2007-01-01

25

Atmospheric inorganic aerosol of a non-industrial city in the centre of an industrial region of the North of Spain, and its possible influence on the climate on a regional scale  

NASA Astrophysics Data System (ADS)

Mineral particles could have influenced on the climate of Oviedo, a non-industrial city situated in the centre of an industrial zone of the North of Spain, increasing the temperature and the precipitations, in spite of the fact that “greenhouse gases” concentrations have diminished in this city in recent years. The directive (1999/30/EC) of the European Commission began to be applied in Oviedo in the year 2003. In agreement with this norm, our first aim was the identification of the inorganic particulate matter of the PM10 and PM2.5 fractions sampled in this city. X-ray diffraction and scanning electron microscopy coupled with X-ray dispersive energy spectrometry were used. The percentages of the different mineral phases of the PM were obtained by a Rietveld refinement of powder X-ray diffraction data. The compositions of the PM10 and PM2.5 fractions of this city are similar. Sulphates are the most abundant particles in the both fractions. Most sulphates, nitrates and sal-ammoniac would have formed by reaction between solid, liquid and/or gas particles and they could be associated with the power stations near to the city and traffic. Wüstite and haematites come from the iron and steel industries of Gijón and Avilés. The main natural sources of halite and carbonates and silicates are sea spray and soil resuspension by the wind, respectively.

Rodríguez, Irene; Galí, Salvador; Marcos, Celia

2009-02-01

26

Regional scale evaporation and the atmospheric boundary layer  

Microsoft Academic Search

Evaporation into the atmosphere is fundamental to the fields of hydrology, meteorology, and climatology. With evolving interest in regional and global hydrologic processes there is an increasing recognition of the importance of the study of evaporation and land surface water balances for length scales of the order of 10 km. To obtain regional scale fluxes of water vapor, heat, and

Marc B. Parlange; William E. Eichinger; Eichinger; Albertson

1995-01-01

27

Regional climatic effects of atmospheric SO2 on Mars  

NASA Technical Reports Server (NTRS)

The conditions under which the valley networks on Mars may have formed remains controversial. The magnitude of an atmospheric greenhouse effect by an early massive CO2 atmosphere has recently been questioned by Kasting. Recent calculations indicate that if solar luminosity were less than about 86 percent of its current value, formation of CO2 clouds in the Martian atmosphere would depress the atmospheric lapse rate and reduce the magnitude of surface warming. In light of recent revisions of magma generation on Mars during each Martian epoch, and the suggestions by Wanke et al. that the role of liquid SO2 should be more carefully explored, we have recalculated the potential greenhouse warming by atmospheric SO2 on Mars, with an emphasis on more localized effects. In the vicinity of an active eruption, the concentration of atmospheric SO2 will be higher than if it is assumed that the erupted SO2 is instantaneously globally distributed. The local steady-state concentration of SO2 is a function of the rate at which it is released, its atmospheric lifetime, and the rate at which local winds act to disperse the SO2. We have made estimates of eruption rates, length of eruption, and dispersion rates of volcanically released SO2, for a variety of atmospheric conditions and atmospheric lifetimes of SO2 to explore the maximum regional climatic effect of SO2.

Postawko, S. E.; Fanale, F. P.

1992-01-01

28

NAO influence on sea ice extent in the Eurasian coastal region Claes Rooth,2  

E-print Network

NAO influence on sea ice extent in the Eurasian coastal region Aixue Hu,1 Claes Rooth,2 Rainer; published 20 November 2002. [1] Influence of winter pre-conditioning of Arctic sea ice due to atmospheric forcing associated with the North Atlantic Oscillation (NAO) on the reduction in summer sea ice extent

Hu, Aixue

29

The Influence of Atmospheric Stability on Potential Evaporation  

Microsoft Academic Search

The Penman relationship for potential evaporation is modified to simply include the influence of atmospheric stability on turbulent transport of water vapor. Explicit expressions for the stability-dependent, surface exchange coefficient developed by Louis are used. The diurnal variation of potential evaporation is computed for the stability-dependent and original Penman relationships using Wangara data.The influence of afternoon instability increases the aerodynamic

L. Mahrt; Michael Ek

1984-01-01

30

Identifying human influences on atmospheric temperature  

PubMed Central

We perform a multimodel detection and attribution study with climate model simulation output and satellite-based measurements of tropospheric and stratospheric temperature change. We use simulation output from 20 climate models participating in phase 5 of the Coupled Model Intercomparison Project. This multimodel archive provides estimates of the signal pattern in response to combined anthropogenic and natural external forcing (the fingerprint) and the noise of internally generated variability. Using these estimates, we calculate signal-to-noise (S/N) ratios to quantify the strength of the fingerprint in the observations relative to fingerprint strength in natural climate noise. For changes in lower stratospheric temperature between 1979 and 2011, S/N ratios vary from 26 to 36, depending on the choice of observational dataset. In the lower troposphere, the fingerprint strength in observations is smaller, but S/N ratios are still significant at the 1% level or better, and range from three to eight. We find no evidence that these ratios are spuriously inflated by model variability errors. After removing all global mean signals, model fingerprints remain identifiable in 70% of the tests involving tropospheric temperature changes. Despite such agreement in the large-scale features of model and observed geographical patterns of atmospheric temperature change, most models do not replicate the size of the observed changes. On average, the models analyzed underestimate the observed cooling of the lower stratosphere and overestimate the warming of the troposphere. Although the precise causes of such differences are unclear, model biases in lower stratospheric temperature trends are likely to be reduced by more realistic treatment of stratospheric ozone depletion and volcanic aerosol forcing. PMID:23197824

Santer, Benjamin D.; Painter, Jeffrey F.; Mears, Carl A.; Doutriaux, Charles; Caldwell, Peter; Arblaster, Julie M.; Cameron-Smith, Philip J.; Gillett, Nathan P.; Gleckler, Peter J.; Lanzante, John; Perlwitz, Judith; Solomon, Susan; Stott, Peter A.; Taylor, Karl E.; Terray, Laurent; Thorne, Peter W.; Wehner, Michael F.; Wentz, Frank J.; Wigley, Tom M. L.; Wilcox, Laura J.; Zou, Cheng-Zhi

2013-01-01

31

Preface: Subsurface, surface and atmospheric processes in cold regions hydrology  

Technology Transfer Automated Retrieval System (TEKTRAN)

This special section presents papers from three sessions at the 24th General Assembly of the International Union of Geodesy and Geophysics (IUGG), held in Perugia, Italy, in July 2007: ‘Interactions between snow, vegetation and the atmosphere’, ‘Hydrology in mountain regions’ and ‘Climate-permafrost...

32

Regional-Scale Carbon Flux Partitioning Using Atmospheric Carbonyl Sulfide  

NASA Astrophysics Data System (ADS)

Simultaneous analysis of atmospheric concentrations of carbonyl sulfide (COS) and carbon dioxide (CO2) has been proposed as an approach to partitioning gross primary production and respiration fluxes at regional and global scales. The basis for this approach was that the observation and regional gradients in atmospheric CO2 are dominated by net ecosystem fluxes while regional gradients in atmospheric COS are dominated by GPP-related plant uptake. Here we investigate the spatial and temporal gradients in airborne COS and CO2 measurements in comparison to flux estimates from ecosystem models and eddy covariance methods over North America. The spatial gradients in the ecosystem relative uptake (ERU), the normalized ratio of COS and CO2 vertical gradients, were consistent with the theoretical relationship to flux estimates from ecosystem models and eddy covariance methods. The seasonality of the gross primary productivity flux estimates was consistent with airborne observations in the midwestern region but had mixed results in the southeastern region. Inter-annual changes in the ERU and regional drought index data suggested a potential relationship between drought stress and low ratios of gross primary production to net ecosystem exchange.

Abu-Naser, M.; Campbell, J. E.; Berry, J. A.

2011-12-01

33

Scaling from Flux Towers to Ecosystem Models: Regional Constraints on GPP from Atmospheric Carbonyl Sulfide  

NASA Astrophysics Data System (ADS)

Process-level information on terrestrial carbon fluxes are typically observed at small spatial scales (e.g. eddy flux towers) but critical applications exist at much larger spatial scales (e.g. global ecosystem models). New methodologies are needed to fill this spatial gap. Recent work suggests that analysis of atmospheric carbonyl sulfide (COS) could fill this gap by providing constraints on GPP fluxes at large scales. This proposal is based on evidence that COS plant uptake is quantitatively related to photosynthesis and that COS plant uptake is the dominant COS budget flux influencing atmospheric concentrations over northern extratropical continents. Previous atmospheric analysis of COS has focused on continental or larger scales and only one ecosystem model. Here we explore the spatial and temporal COS variation within North America and their relationship to a range of ecosystem models using regional and global atmospheric transport models. Airborne COS observations are examined from the NOAA-ESRL network including 13 North American airborne sites and a total of 1,447 vertical profiles from years 2004 to 2012. In addition to COS plant uptake, we examined the influence of atmospheric transport treatments, boundary conditions, soil fluxes (mechanistic and empirical), and anthropogenic emissions. The atmospheric COS simulations were consistent with the primary observed spatial and temporal variations in the US mid-continent. This consistency is supportive of ecosystem models because the dominant input for these atmospheric COS simulations is ecosystem model GPP data. However, only the COS simulations driven by a subset of the ecosystem models were able to reproduce the observed COS seasonality in a semiarid cultivated region (ARM/SGP). This subset of ecosystem models produced GPP seasonality that was similar to eddy flux estimates, suggesting a role for COS observations in extending flux tower data to regional spatial scales.

Abu-Naser, M.; Campbell, J.; Berry, J. A.; Seibt, U.; Maseyk, K. S.; Torn, M. S.; Biraud, S. C.; Fischer, M. L.; Billesbach, D. P.; Baker, I. T.; Collatz, G. J.; Chen, H.; Montzka, S. A.; Sweeney, C.

2012-12-01

34

Active region influences upon the solar constant  

NASA Technical Reports Server (NTRS)

The influence that active regions have upon the solar constant is discussed. Sunspots appear to lower the solar constant for the few days in which they are located near central meridian. This raises the possibility that an 11-year, solar-cycle-related depression in the solar constant may occur. Recent findings concerning the physics of active regions suggest that sunspots and faculae are largely surface features. Within that surface faculae reradiate, within a few weeks, the 'missing energy' associated with sunspots. This is consistent with the observations showing that the solar constant does not have an 11-year cycle-related depression that some authors predicted. However, there is a secular variation in the solar constant, whose explanation is not completely understood.

Schatten, Kenneth H.; Mayr, Hans G.; Omidvar, Kazem

1987-01-01

35

Canopy influence on trace metal atmospheric inputs on forest ecosystems: Speciation in throughfall  

E-print Network

Canopy influence on trace metal atmospheric inputs on forest ecosystems: Speciation in throughfall canopy interaction with atmospheric inputs, TM were measured in both Open Field Bulk Deposition (BD emissions trends. Canopy greatly influences precipitation composition, through different processes

Mailhes, Corinne

36

Improving SLCF Science in the Himalayan Region: ICIMOD's Atmosphere Initiative  

NASA Astrophysics Data System (ADS)

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.

Panday, A. K.; Pradhan, B. B.; Surapipith, V.

2013-12-01

37

Regional differences in worldwide emissions of mercury to the atmosphere  

Microsoft Academic Search

Annual emissions of anthropogenic Hg to the atmosphere in different regions of the world during the last decade show an interesting dichotomy: the emissions in the developed countries increased at the rate of about 4.5–5.5% yr?1 up to 1989 and have since remained nearly constant, while in developing countries the emissions continue to rise steadily at the rate of 2.7–4.5%

Nicola Pirrone; Gerald J. Keeler; Jerome O. Nriagu

1996-01-01

38

Influence of transport and ocean ice extent on biogenic aerosol sulfur in the Arctic atmosphere  

NASA Astrophysics Data System (ADS)

The recent decline in sea ice cover in the Arctic Ocean could affect the regional radiative forcing via changes in sea ice-atmosphere exchange of dimethyl sulfide (DMS) and biogenic aerosols formed from its atmospheric oxidation, such as methanesulfonic acid (MSA). This study examines relationships between changes in total sea ice extent north of 70°N and atmospheric MSA measurement at Alert, Nunavut, during 1980-2009; at Barrow, Alaska, during 1997-2008; and at Ny-Ålesund, Svalbard, for 1991-2004. During the 1980-1989 and 1990-1997 periods, summer (July-August) and June MSA concentrations at Alert decreased. In general, MSA concentrations increased at all locations since 2000 with respect to 1990 values, specifically during June and summer at Alert and in summer at Barrow and Ny-Ålesund. Our results show variability in MSA at all sites is related to changes in the source strengths of DMS, possibly linked to changes in sea ice extent as well as to changes in atmospheric transport patterns. Since 2000, a late spring increase in atmospheric MSA at the three sites coincides with the northward migration of the marginal ice edge zone where high DMS emissions from ocean to atmosphere have previously been reported. Significant negative correlations are found between sea ice extent and MSA concentrations at the three sites during the spring and June. These results suggest that a decrease in seasonal ice cover influencing other mechanisms of DMS production could lead to higher atmospheric MSA concentrations.

Sharma, S.; Chan, E.; Ishizawa, M.; Toom-Sauntry, D.; Gong, S. L.; Li, S. M.; Tarasick, D. W.; Leaitch, W. R.; Norman, A.; Quinn, P. K.; Bates, T. S.; Levasseur, M.; Barrie, L. A.; Maenhaut, W.

2012-06-01

39

The Regional Atmospheric Modeling System (RAMS): Development for Parallel Processing Computer  

E-print Network

) of the planetary boundary layer. Its most frequent applications are to simulate atmospheric phenomenaThe Regional Atmospheric Modeling System (RAMS): Development for Parallel Processing Computer. Walko Department of Atmospheric Science, Colorado State University and Mission Research Corporation

Cirne, Walfredo

40

The Influence of COSMIC Satellite Data on Regional Analysis  

NASA Astrophysics Data System (ADS)

The atmospheric limb sounding technique making use of radio signals transmitted by the Global Position System (GPS) has emerged as a promising approach for global atmospheric measurements. As demonstrated by the proof-of-concept GPS Meteorology (GPS/MET) experiment and more recently by the CHAMP and SAC-C missions, the GPS radio occultation (RO) sounding data are of high accuracy and high vertical resolution. On 15 April 2006, the joint U.S.-Taiwan COSMIC/FORMOSAT-3 mission, a constellation of six microsatellites, was launched from the Vandenberg Air Force Base. These satellites are being deployed to their final orbits, which would take about a year. During the early phase of the deployment, the satellites are closely located. This offers a unique opportunity to examine the precision of the GPS RO measurements. The COSMIC data are available in near real-time for global weather analysis and prediction and for climate monitoring. Currently, COSMIC is producing approximately 1300 GPS RO soundings per day at the end of August 2006. This number will be increased as the satellites are further separated through the deployment process. Radio occultation measures phase and amplitude of the microwave signals emitted from GPS. These signals are inverted to obtain profiles of signal bending, atmospheric refractivity, pressure temperature and water vapor. The main objective of the COSMIC/FORMOSAT-3 mission is to demonstrate the value of these radio occultation products for weather forecasting, climate monitoring, ionospheric research and space weather prediction. This presentation will provide an overview of the COSMIC/FORMOSAT-3 program. We will present results on the influence of COSMIC data on the regional analysis over the data void regions, particularly over the tropics and high latitudes. For further information on the COSMIC/FORMOSAT-3, please refer to http://www.cosmic.ucar.edu/.

Kuo, Y.

2006-12-01

41

Critical review of studies on atmospheric dispersion in coastal regions  

SciTech Connect

This study effort was required as a preliminary step prior to initiation of field measurements of atmospheric dispersion in coastal regions. The Nuclear Regulatory Commission (NRC) is in the process of planning an extensive field measurement program to generate data which will serve as improved data bases for licensing decisions, confirmation of regulations, standards, and guides, and for site characterizations. The study being reported here is an effort directed to obtaining as much information as is possible from existing studies that is relevant toward NRC's objectives. For this study, reports covering research and meteorological measurements conducted for industrial purposes, utility needs, military objectives, and academic studies were obtained and critically reviewed in light of NRC's current data needs. This report provides an interpretation of the extent of existing usable information, an indication of the potential for tailoring existing research toward current NRC information needs, and recommendations for several follow-on studies which could provide valuable additional information through reanalysis of the data. Recommendations are also offered regarding new measurement programs. Emphasis is placed on the identification and acquisition of data from atmospheric tracer studies conducted in coastal regions. A total of 225 references were identified which deal with the coastal atmosphere, including meteorological and tracer measurement programs, theoretical descriptions of the relevant processes, and dispersion models.

Shearer, D.L.; Kaleel, R.J.

1982-09-01

42

A subtropical North Atlantic regional atmospheric moisture budget  

NASA Astrophysics Data System (ADS)

synergistic effects of evaporation (E), precipitation (P), and Ekman transport make the Salinity Processes in the Upper Ocean Regional Study (SPURS-1) region in the subtropical North Atlantic (15-30°N, 30-45°W) the natural location for the world's highest open ocean SSS maximum. Using the MERRA and ERA-Interim atmospheric reanalyses, we reproduce the mean hydrologic state of the atmosphere over the SPURS-1 region since 1979 and roughly deduce the change in salinity across the meridional domain due solely to interactions between E-P and Ekman transport. Our findings suggest a region that is highly evaporative at a mean rate of 4.87 mm/d with a standard deviation of 1.2 mm/d and little seasonality. Precipitation is much more variable with an annual fall maximum around 3 mm/d but only a mean rate of 1.37 mm/d with a standard deviation of 1.46 mm/d. The resulting E-P variable has a mean rate of 3.50 mm/d with a standard deviation of 1.92 mm/d and matches well with the moisture flux divergence term although the former is typically larger by a small margin. Strong prevailing easterly trade winds generate northward Ekman transports that advect water toward the salinity maximum around 25°N. A short calculation shows that atmospheric moisture dynamics could potentially account for about one third of the change in salinity between 15°N and 25°N giving an estimate of the role that surface freshwater flux plays in the maintenance of the salinity maximum.

D'Addezio, Joseph M.; Bingham, Frederick M.

2014-12-01

43

Influence of atmospheric turbulence on planetary transceiver laser ranging  

NASA Astrophysics Data System (ADS)

In this paper we investigate the influence of atmospheric turbulence on the performance of the uplink of a planetary transceiver laser ranging system using a single photon detector. We numerically combine the influence of turbulence in the mean intensity profile variations, scintillation, beam-wander induced pointing errors and stochastic time-of-flight variations, using the Hufnagel-Valley turbulence profile to model the ground turbulence behavior. We map the intensity variations due to turbulence to variations in the probability distribution of the arrival time of the 1st photon in a laser pulse, which influences the range measurement error probability distribution. The turbulence models are applied to assess the influence on single-pass range accuracy and precision statistics, as well as the parameter estimation quality of a Phobos Laser Ranging (PLR) mission. The difference in range measurement error between weak and strong turbulence is 3-4 mm in a PLR concept. This indicates that turbulence is a potentially important contributor to the error budget of interplanetary laser ranging missions, which aim at mm-level accuracy and precision. The single-shot precision is weakly influenced by turbulence, but strong turbulence is found to cause a strong decrease in detected pulse fraction, reducing normal point precision. We show that a trade-off between range accuracy and precision must be made when selecting laser system parameters, considerations for which are influenced by atmospheric turbulence effects. By consistently operating at the single-photon signal strength level, accuracy variations can be largely removed, at the expense of normal point precision, due to the reduced detection probability. We perform parameter estimation of Phobos initial state and observation biases using simulated measurements with and without turbulence, using a daily periodic turbulence strength model. We show that the parameter estimation quality is degraded significantly below that of the turbulence-free case only in the presence of strong turbulence. This shows the existence of a limit of ground turbulence strength below which its influence on parameter estimation becomes negligible.

Dirkx, D.; Noomen, R.; Prochazka, I.; Bauer, S.; Vermeersen, L. L. A.

2014-12-01

44

Extensive regional atmospheric hydrocarbon pollution in the southwestern United States  

PubMed Central

Light alkane hydrocarbons are present in major quantities in the near-surface atmosphere of Texas, Oklahoma, and Kansas during both autumn and spring seasons. In spring 2002, maximum mixing ratios of ethane [34 parts per 109 by volume (ppbv)], propane (20 ppbv), and n-butane (13 ppbv) were observed in north-central Texas. The elevated alkane mixing ratios are attributed to emissions from the oil and natural gas industry. Measured alkyl nitrate mixing ratios were comparable to urban smog values, indicating active photochemistry in the presence of nitrogen oxides, and therefore with abundant formation of tropospheric ozone. We estimate that 4–6 teragrams of methane are released annually within the region and represents a significant fraction of the estimated total U.S. emissions. This result suggests that total U.S. natural gas emissions may have been underestimated. Annual ethane emissions from the study region are estimated to be 0.3–0.5 teragrams. PMID:14530403

Katzenstein, Aaron S.; Doezema, Lambert A.; Simpson, Isobel J.; Blake, Donald R.; Rowland, F. Sherwood

2003-01-01

45

Assessing the contribution of natural sources to regional atmospheric mercury budgets  

SciTech Connect

Contributions to the global atmospheric mercury budget originate from natural and anthropogenic sources. Constraining inputs from anthropogenic point sources has been the emphasis of past research leaving the contribution from diffuse natural and anthropogenic mercury enriched landscapes poorly constrained and underestimated. From September 1--4, 1997 mercury researchers convened in Reno, NV, US to intercompare methods used to determine in situ mercury flux from a naturally enriched landscape. Data collected indicate that naturally mercury-enriched areas constitute a significant atmospheric Hg source term. Mercury fluxes of 30 to 2,000 ng/m{sup 2} h were measured at the Steamboat springs Geothermal Area. These values are one to three orders of magnitude greater than that applied for natural sources in global mercury budgets. Air concentrations measured in the area indicate that natural sources can increase ambient levels above background concentrations. Assessment of these and other data indicate that natural sources constitute a significant source of atmospheric mercury that is available to the global mercury budget, and that the strength of the source is influenced significantly by environmental factors. Determining the contribution of mercury to the atmosphere from diffuse terrestrial sources is necessary to develop local and regional baselines for environmental regulations and risk assessments, and valid emission inventories. A scaling up mercury fluxes measured for diffuse terrestrial surfaces suggests that the natural atmospheric mercury source term in the US is comparable to the anthropogenic source term.

Gustin, M.S. [Univ. of Nevada, Reno, NV (United States). Dept. of Environmental and Resource Sciences; Lindberg, S.E. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

1997-12-31

46

Source identification of aerosols influencing atmospheric extinction: Integrating PMF and PSCF with emission inventories and satellite observations  

Microsoft Academic Search

The relative influence of source categories of aerosols that affect atmospheric extinction is analyzed by evaluating the potential source contribution function (PSCF) based source regions of the positive matrix factorization (PMF) estimated factors against satellite retrievals of aerosol index and active fires and combining with emission inventory information. This approach has been applied to aerosol chemical data obtained from the

R. Cherian; C. Venkataraman; A. Kumar; M. M. Sarin; A. K. Sudheer; S. Ramachandran

2010-01-01

47

Middle Atmosphere Program. Handbook for MAP. Volume 16: Atmospheric Structure and Its Variation in the Region 20 to 120 Km. Draft of a New Reference Middle Atmosphere  

NASA Technical Reports Server (NTRS)

A draft of a new reference atmosphere for the region between 20 and 80 km which depends largely on recent satellite experiments covering the globe from 80 deg S to 80 deg N is given. A separate international tropical reference atmosphere is given, as well as reference ozone models for the middle atmosphere.

Labitzke, K. (editor); Barnett, J. J. (editor); Edwards, B. (editor)

1985-01-01

48

Influence of local and regional sources on the observed spatial and temporal variability of size resolved atmospheric aerosol mass concentrations and water-soluble species in the Athens metropolitan area  

NASA Astrophysics Data System (ADS)

The variability of common aerosol species in large Metropolitan urban areas is a major air quality issue with strong health impacts of large populations. PM10 and PM2.5 particulate matter samples were obtained at three sites characteristic of industrial, urban traffic and sub-urban residential areas in the Athens basin. Samples were analysed for anions (Cl-, NO3-, SO42-) and cations (K+, Na+, Ca2+, Mg2+, NH4+) using ion chromatography. The spatial and temporal variability for the particulate matter (PM) concentration mass and water-soluble ionic species concentrations for the investigated sites were studied. Mean PM fine concentration levels were 20% higher at the industrial and the central urban areas compared to those in the suburban area (24.2 ?g/m3). The mean values for the coarse fraction at those two sites were two to three times higher compared to those at the suburban site (12.4 ?g/m3). Comparable concentration levels of most species were observed in all areas, while SO42- and NO3- differ at a significant level. Furthermore, the average size distributions of the mass and individual ions at the suburban site (NCSR Demokritos) showed a bimodal size distribution. SO42- and NH4+ have their main peak in the fine fraction while NO3- showed equal distribution on the fine and coarse mode.. Good correlation was found for SO42- and NO3- with Ca2+ and Na+ with Cl- for the coarse fraction in the industrial area. NH4+ was closely correlated with SO42- in the fine particles and in all areas. For the urban site the best correlations in coarse particulates were reported between Na+/Mg2+-Cl-, Ca2+/Mg2+-SO42-, explained by neutralization of acidic aerosol by soil dust and sea salt in the coarse fraction. Moreover, time weighted concentrations roses at the industrial and urban sites, showed no significant directional dependence, indicating either uniform generation of mainly the coarse species within the metropolitan area or major influence of the regional background for the fine aerosol species.

Eleftheriadis, Konstantinos; Ochsenkuhn, Klaus M.; Lymperopoulou, Theopisti; Karanasiou, Angeliki; Razos, Panayiotis; Ochsenkuhn-Petropoulou, Maria

2014-11-01

49

Influence of seasonal cycles in Martian atmosphere on entry, descent and landing sequence  

NASA Astrophysics Data System (ADS)

The phenomena like high eccentricity of Martian orbit, obliquity of the orbital plane and close alignment of the winter solstice and the orbital perihelion, separately or together can significantly alter not only the level of some Martian atmospheric parameters but also the characteristics of its diurnal and seasonal cycle. Considering that entry, descent and landing (EDL) sequence is mainly driven by the density profile of the atmosphere and aerodynamic characteristic of the entry vehicle. We have performed the analysis of the influence of the seasonal cycles of the atmospheric parameters on EDL profiles by using Mars Global Reference Atmospheric Model (Mars-GRAM). Since the height of the deployment of the parachute and the time passed from the deployment to propulsion firing (descent time) are of crucial importance for safe landing and the achievable landing site elevation we paid special attention to the influence of the areocentric longitude of the Sun (Ls) on these variables. We have found that these variables have periodic variability with respect to Ls and can be very well approximated with a sine wave function whose mean value depends only on the landing site elevation while the amplitudes and phases depend only on the landing site latitude. The amplitudes exhibit behavior which is symmetric with respect to the latitude but the symmetry is shifted from the equator to the northern mid-tropics. We have also noticed that the strong temperature inversions which are usual for middle and higher northern latitudes while Mars is around its orbital perihelion significantly alter the descent time without influencing the height of the parachute deployment. At last, we applied our model to determine the dependence of the accessible landing region on Ls and found that this region reaches maximum when Mars is around the orbital perihelion and can vary 50° in latitude throughout the Martian year.

Mar?eta, Dušan; Šegan, Stevo; Rašuo, Boško

2014-05-01

50

Influence of Atmospheric Pressure and Composition on LIBS  

SciTech Connect

Most LIBS experiments are conducted at standard atmospheric pressure in air. However, there are LIBS studies that vary the pressure and composition of the gas. These studies have provided insights into fundamentals of the mechanisms that lead to the emission and methods for improving the quality of LIBS spectra. These atmospheric studies are difficult because the effects of pressure and gas composition and interconnected, making interpretation of the results difficult. The influence of pressures below and above 760 Torr have been explored. Performing LIBS on a surface at reduced pressures (<760 Torr) can result in enhanced spectra due to higher resolution, increased intensity, improved signal-to-noise (S/N), and increased ablation. Lower pressures produce increased resolution because the line width in LIBS spectra is predominantly due to Stark and Doppler broadening. Stark broadening is primarily caused from collisions between electrons and atoms, while Doppler broadening is proportional to the plasma temperature. Close examination using a high resolution spectrometer reveals that spectra show significant peak broadening and self-absorption as pressures increase, especially for pressures >760 Torr. During LIBS plasma expansion, energy is lost to the surrounding atmosphere, which reduces the lifetime of the laser plasma. Therefore, reducing the pressure increases the lifetime of the plasma, allowing more light from the laser plasma to be collected; thus, increasing the observed signal intensity. However, if pressures are too low (<10 Torr), then there is a steep drop in LIBS spectral intensity. This loss in intensity is mostly due to a disordered plasma that results from the lack of sufficient atmosphere to provide adequate confinement. At reduced pressures, the plasma expands into a less dense atmosphere, which results in a less dense shock wave. The reduced density in the shock wave results in reduced plasma shielding, allowing more photons to reach the sample. Increasing the number of photons interacting with the sample surface results in increased ablation, which can lead to increased intensity. The composition of the background gas has been shown to greatly influence the observed LIBS spectra by altering the plasma temperature, electron density, mass removal, and plasma shielding that impact the emission intensity and peak resolution. It has been reported that atmospheric Ar results in the highest plasma temperature and electron density, while a He atmosphere results in the lowest plasma temperatures and electron density. Studying temporal data, it was also found that Ar had the slowest decay of both electron density and plasma temperature, while He had the fastest decay in both parameters. The higher plasma temperature and electron density results in an increase in line broadenin, or poor resolution, for Ar compared to He. A rapidly developing LIBS plasma with a sufficient amount of electrons can absorb a significant portion of the laser pulse through inverse Bremsstahlung. Ar (15.8 eV ) is more easily ionized than He (24.4 eV). The breakdown threshold for He at 760 Torr is approximately 3 times greater than Ar and approximately 5 times greater at 100 Torr. The lower breakdown threshold in Ar, compared to He, creates an environment favorable for plasma shielding, which reduces sample vaporization and leads to a weaker LIBS signal.

Jeremy J. Hatch [Pacific Univ., Forest Grove, OR (United States). Dept. of Chemistry; Jill R. Scott [Idaho National Laboratory (INL), Idaho Falls, ID (United States). Chemical and Radiation Measurement; Effenberger, A. J. Jr. [Univ. of California, San Diego, CA (United States). Center for Energy Research

2014-03-01

51

Magnetic Field Influence on Atmospheric Escape and Planetary Evolution  

NASA Astrophysics Data System (ADS)

Planetary magnetic fields are maintained by a convective dynamo within the deep interior but their influence extends all the way up to the magnetopause, where the solar wind is deflect around the planet. The presence of a magnetic field is thought to influence the atmosphere-solar wind interaction in a variety of ways, but there is no clear consensus as to whether it impedes or facilitates volatile loss to space. Escape of planetary atmospheres to space is of central importance to studying the evolution of planetary climates, volatile exchange with the interior, and interaction with the space environment. Out of the terrestrial planets Earth has by far the largest surface hydrogen inventory (mainly in the form of liquid water) and furthest magnetopause at ~10 Earth radii. Evidence from volatile concentrations and isotopic ratios imply that Mars and Venus have both lost a significant amount of H over their history, and have maintained little to no magnetic barrier, respectively, to hold off the erosive solar wind. Venus is a particularly interesting case because it is most similar to Earth in mass and density, yet has no detectable magnetic field and an isotopic D/H ratio that implies the loss of a significant amount of water in the past. Is the decline of Venus' dynamo related to the loss of hydrogen from its atmosphere? Is the stability of Earth's unusually large volatile reservoir over billions of years related to the presence of a strong magnetic field over that period of time? We explore conditions under which the presence of a magnetic barrier at the top of the atmosphere may operate as an additional limit to escape. We derive a model for magnetic field limited escape that depends on the terrestrial number density, area, scale height, and loss time scale at the magnetopause. This model predicts rapid escape when magnetic field is weak and magnetopause altitude is low, and a decrease in escape as magnetic field strength increases. This coupling between field strength and escape may be part of a larger negative feedback mechanism that stabilizes climate, tectonic regime, and dynamo action. Such a feedback is possible by a coupling between surface temperature and tectonic regime. Numerical simulations of mantle convection with damage demonstrate that low surface temperature stagnates grain growth and promotes surface convection, which increases the core cooling rate and magnetic field intensity. Therefore, magnetic limited escape may be part of a whole planet coupling that has stabilized Earth's volatile reservoir, surface tectonics, and magnetic field.

Driscoll, P. E.; Bercovici, D.

2012-12-01

52

The Influence of Large Solar Proton Events on the Atmosphere  

NASA Technical Reports Server (NTRS)

Solar proton events (SPEs) can cause changes in constituents in the Earth s polar middle atmosphere. A number of large SPEs have occurred over the past 50 years and tend to happen most frequently near solar maximum. The highly energetic protons cause ionizations, excitations, dissociations, and dissociative ionizations of the background constituents. Complicated ion chemistry leads to HOx (H, OH, HO2) production and dissociation of N2 leads to NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2) production. Both the HOx and NOy increases can result in changes to ozone in the stratosphere and mesosphere. The HOx increases lead to short-lived (days) ozone decreases in the mesosphere and upper stratosphere. The NOy increases lead to long-lived (several months) stratospheric ozone changes because of the long lifetime of NOy constituents in this region. UARS HALogen Occultation Experiment (HALOE) instrument observations showed SPE-caused polar stratospheric NOx (NO+NO2) increases over 10 ppbv in September 2000 due to the very large SPE of July 2000, which are reasonably well simulated with the Whole Atmosphere Community Climate Model (WACCM). WACCM-computed SPE-caused polar stratospheric ozone decreases >10% continued for up to 5 months past the largest events in the past 50 years, however, SPE-caused total ozone changes were not found to be statistically significant. Small polar middle atmospheric temperature changes of <4 K have also been predicted to occur as a result of the larger SPEs. The polar atmospheric effects of large SPEs during solar cycle 23 and 24 will be emphasized in this presentation.

Jackman, Charles H.

2012-01-01

53

Reactive nitrogen oxides in remote regions: Atmospheric concentrations and atmosphere/biosphere exchange  

SciTech Connect

Atmospheric concentrations and elements of the atmospheres/biosphere exchange of reactive nitrogen oxides (NO{sub y}) were measured in two disparate, remote ecosystems: the Amazon rain forest in central Brazil (wet season, 1987) and the moist tundra of southwestern Alaska (summer, 1988). Concentrations of total NO{sub y} and the NO{sub y} species NO and NO{sub 2} in both locations were found to be generally low compared to the few other remote continental regions where measurements have been made. In Alaska the concentrations of NO + NO{sub 2} (=NO{sub x}) were in the range (10-20 pptv) thought to be more typical of marine air masses. Occasional observations of higher concentrations, especially in Brazil, indicated that polluted air reached even these remote sites. The soils in both locations were modest sources of NO{sub x} to the atmosphere. In Brazil this source was approximately balanced, during unpolluted periods, by dry deposition of other NO{sub y} species to the forest canopy, while in Alaska the net flux of NO{sub y} was strongly downward. Diurnal variations in the NO{sub y} concentrations and fluxes at both sites suggest that dry deposition rates are controlled by the supply of reactive components such as HNO{sub 3} and that a significant portion of the observed NO{sub y} may consist of compounds with relatively long tropospheric lifetimes which are resistant to dry deposition.

Bakwin, P.S.

1989-01-01

54

Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models  

Microsoft Academic Search

Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates

Kevin Robert Gurney; Rachel M. Law; A. Scott Denning; Peter J. Rayner; David Baker; Philippe Bousquet; Lori Bruhwiler; Yu-Han Chen; Philippe Ciais; Songmiao Fan; Inez Y. Fung; Manuel Gloor; Martin Heimann; Kaz Higuchi; Jasmin John; Takashi Maki; Shamil Maksyutov; Ken Masarie; Philippe Peylin; Michael Prather; Bernard C. Pak; James Randerson; Jorge Sarmiento; Shoichi Taguchi; Taro Takahashi; Chiu-Wai Yuen

2002-01-01

55

Atmospheric Impact of Large Methane Emission in the Arctic Region  

NASA Astrophysics Data System (ADS)

A highly potent greenhouse gas, methane, is locked in the solid phase as ice-like deposits containing a mixture of water and gas (mostly methane) called clathrates, in ocean sediments and underneath permafrost regions. Clathrates are stable under high pressure and low temperatures. Recent estimates suggest that about 1600 - 2000GtC of clathrates are present in oceans and 400GtC in Arctic permafrost (Archer et al.2009) which is about 4000 times that of current annual emissions. In a warming climate, increase in ocean temperatures could alter the geothermal gradient, which in turn could lead to dissociation of the clathrates and release of methane into the ocean and subsequently into the atmosphere as well. This could be of particular importance in the shallow part of the Arctic Ocean where the clathrates are found in depths of only 300m. In this presentation, we shall show results from our ongoing simulation of a scenario of large scale methane outgassing from clathrate dissociation due to warming ocean temperatures in the Arctic based on ocean sediment modeling. To that end we use the CESM (Community Earth System Model) version 1 with fully active coupled atmosphere-ocean-land model together with fast atmospheric chemistry module to simulate the response to increasing methane emissions in the Barents Sea, Canadian Archipelago and the Sea of Okhotsk. The simulation shows the effect these methane emissions could have on global surface methane, surface ozone, surface air temperature and other related indices. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-491764

Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D.; Reagan, M. T.; Collins, W.; Elliott, S. M.; Maltrud, M. E.

2011-12-01

56

The influence of ionization events on atmospheric ozone  

NASA Technical Reports Server (NTRS)

Atmospheric ionization events can modify the concentration of neutral species in the stratosphere and mesosphere. In particular, ozone is destroyed because of the production of significant quantities of odd nitrogen and hydrogen compounds which react photochemically to destroy ozone. Direct evidence of ozone depletion comes from data taken during and following two solar flares generating large fluxes of 10-100 Mev protons, which bombarded the polar stratosphere and mesosphere. Observations of ozone taken during X-ray emission by solar flares and energetic electron precipitation during aurorae indicates ozone destruction above 50 km by ionization produced odd hydrogen. Lightning is apparently a large contributor to the tropospheric odd nitrogen budget. Ion propulsion induced dumping of the inner proton radiation belt represents a human activity which may influence stratospheric NOx.

Aikin, A. C.

1979-01-01

57

Influence of Industrialization in the Campinas Rural Region.  

ERIC Educational Resources Information Center

The Campinas region of Brazil was studied to determine if the introduction of industrial plants in rural areas influenced the life of the rural population. The purpose of this study was to obtain an insight into the manner by which the industrialization influence is functioning in the Campinas rural area. The region and its rural population were…

Ferrari, Alfonso Trujillo

58

Atmospheric energetics in regions of intense convective activity  

NASA Technical Reports Server (NTRS)

Synoptic-scale budgets of kinetic and total potential energy are computed using 3- and 6-h data at nine times from NASA's fourth Atmospheric Variability Experiment (AVE IV). Two intense squall lines occurred during the period. Energy budgets for areas that enclose regions of intense convection are shown to have systematic changes that relate to the life cycles of the convection. Some of the synoptic-scale energy processes associated with the convection are found to be larger than those observed in the vicinity of mature cyclones. Volumes enclosing intense convection are found to have large values of cross-contour conversion of potential to kinetic energy and large horizontal export of kinetic energy. Although small net vertical transport of kinetic energy is observed, values at individual layers indicate large upward transport. Transfer of kinetic energy from grid to subgrid scales of motion occurs in the volumes. Latent heat release is large in the middle and upper troposphere and is thought to be the cause of the observed cyclic changes in the budget terms. Total potential energy is found to be imported horizontally in the lower half of the atmosphere, transported aloft, and then exported horizontally. Although local changes of kinetic energy and total potential energy are small, interaction between volumes enclosing convection with surrounding larger volumes is quite large.

Fuelberg, H. E.

1977-01-01

59

Modeling evaporation from porous media influenced by atmospheric processes  

NASA Astrophysics Data System (ADS)

Evaporation from porous media into the ambient air involves varios interacting processes and depends on a multitude of properties of the fluids, of the porous medium and of the flow regime. It may be strongly influenced by atmospheric processes, such as an adjacent wind field with the prevailing conditions (wind velocity, temperature, humidity, ...). The evaporation rate can be limited from the porous-medium side, e.g. due to limited water supply by capillary forces or by diffusion through the tortuous porous medium, or from the free-flow side involving the transfer through a boundary layer. Modeling such complex system on the scale of representative elementary volumes (REVs) is a challenging task. In Mosthaf et al. (WRR 2011), we have developed a model for the coupled simulation of a two-phase porous medium flow (Darcy) and a laminar free flow (Stokes) under non-isothermal conditions. This is based on flux continuity across the interface and on a local thermodynamic equilibrium and has the evaporation rate as an output. The computed rates have been significantly lower as the ones which were obsereved in wind tunnel experiments performed in the group of Dani Or (ETH Zürich). One probable reason for that is that the ambient air flow is usually turbulent involving the formation of thin boundary layers with steep gradients and a dispersive mixing of vapor in the free flow, which has to be accounted for. Therefore, several simplified turbulence and boundary layer models with different complexity are being examined with respect to their ability to improve the representation of the flow and transport behavior especially in the vicinity of the interface between soil and atmosphere. Numerical examples illustrate the influence of certain processes and parameters on the computed evaporative fluxes. Possible extensions and simplifications to the developed laminar coupled model are discussed.

Helmig, R.; Mosthaf, K.; Baber, K.; Flemisch, B.

2012-12-01

60

Regional forecasting with global atmospheric models; Final report  

SciTech Connect

The purpose of the project was to conduct model simulations for past and future climate change with respect to the proposed Yucca Mtn. repository. The authors report on three main topics, one of which is boundary conditions for paleo-hindcast studies. These conditions are necessary for the conduction of three to four model simulations. The boundary conditions have been prepared for future runs. The second topic is (a) comparing the atmospheric general circulation model (GCM) with observations and other GCMs; and (b) development of a better precipitation data base for the Yucca Mtn. region for comparisons with models. These tasks have been completed. The third topic is preliminary assessments of future climate change. Energy balance model (EBM) simulations suggest that the greenhouse effect will likely dominate climate change at Yucca Mtn. for the next 10,000 years. The EBM study should improve rational choice of GCM CO{sub 2} scenarios for future climate change.

Crowley, T.J.; Smith, N.R. [Applied Research Corp., College Station, TX (United States)

1994-05-01

61

Sensitivity of Ebro Delta region dynamics to atmospheric forcing. An Ensemble modelling approach.  

NASA Astrophysics Data System (ADS)

The dynamics in the Ebro Delta region of the Catalan shelf (NW Mediterranean) is mostly driven by the joint effect of the large scale circulation (the so-called Northern Current), the Ebro river runoff and the atmospheric forcing. Bottom topography, characterized by a shelf widening and a steep slope, also plays an important role. What is proposed in this sensitivity study is to use an Ensemble method to evaluate the impact of the atmospheric forcing on the dynamics of the region, leading to a better understanding of the coastal ocean response. This study is also meant as a preliminary step in the preparation of a data assimilation scheme in the area. In this purpose, pseudo-random a priori Ensembles are generated by perturbing properties believed to belong to the error subspace. In order to get the best possible representation of the dynamics the numerical model chosen is the SYMPHONIE model, which solves the primitive equations in finite differences using generalized sigma coordinates in the vertical. Then we perturb the atmospheric forcings to generate Ensembles of ocean solutions which we use consequently to determine the ocean error statistics and error growth associated with forcing uncertainties. We also show the main features of the influence functions of potential observations in the coastal domain.

Jorda, G.; de Mey, P.; Marsaleix, P.; Espino, M.

2003-04-01

62

Soil occupation and atmospheric variations over Sobradinho Lake area. Part two: a regional modeling study  

NASA Astrophysics Data System (ADS)

The impact of the changes on soil cover and land use brought about by the construction of the Sobradinho Dam in the semi-arid region of the São Francisco River Hydrographic Basin is analyzed by means of a numerical model RAMS. Disregarding the influence of a large scale flow, a set of factors were responsible for the creation of a rather complex circulation system that includes mountain-valley winds, lake breeze (LB) and non-conventional circulation all induced by the surface non-homogeneous aspect. Results have demonstrated that the implementation of works of such magnitude brings about environmental changes in an area that stretches far beyond the surroundings of the reservoir. The soil cover alterations due to the ever increasing development of the area with the presence of irrigated crops in a sparsely vegetated region ( caatinga) does affect land surface characteristics, occasioning for that matter the splitting of the available energy into latent and sensible heat fluxes. LB behavior varies in accordance with atmospheric conditions and also in view of the type of vegetation found in the lake surrounding areas. Hydro availability in root zones, even under adverse atmospheric conditions (high temperature and low air humidity) brings up the high rates of evaporation and plant transpiration that contribute towards the increase of humidity and the fall of temperature in lower atmospheric layers.

Correia, M. F.; da Silva Dias, M. A. F.; da Silva Aragão, M. R.

2006-11-01

63

Natural sources of atmospheric aerosols influencing air quality across Europe.  

PubMed

Atmospheric aerosols are emitted by natural and anthropogenic sources. Contributions from natural sources to ambient aerosols vary widely with time (inter-annual and seasonal variability) and as a function of the distance to source regions. This work aims to identify the main natural sources of atmospheric aerosols affecting air quality across Europe. The origin, frequency, magnitude, and spatial and temporal variability of natural events were assessed for the years 2008 and 2009. The main natural sources of atmospheric aerosols identified were African dust, sea spray and wildfires. Primary biological particles were not included in the present work. Volcanic eruptions did not affect air quality significantly in Europe during the study period. The impact of natural episodes on air quality was significant in Southern and Western Europe (Cyprus, Spain, France, UK, Greece, Malta, Italy and Portugal), where they contributed to surpass the PM10 daily and annual limit values. In Central and Northern Europe (Germany, Austria and Latvia) the impact of these events was lower, as it resulted in the exceedance of PM daily but not annual limit values. Contributions from natural sources to mean annual PM10 levels in 2008 and 2009 ranged between 1 and 2 ?g/m(3) in Italy, France and Portugal, between 1 and 4 ?g/m(3) in Spain (10 ?g/m(3) when including the Canary Islands), 5 ?g/m(3) in UK, between 3 and 8 ?g/m(3) in Greece, and reached up to 13 ?g/m(3) in Cyprus. The evaluation of the number of monitoring stations per country reporting natural exceedances of the daily limit value (DLV) is suggested as a potential tool for air quality monitoring networks to detect outliers in the assessment of natural contributions. It is strongly suggested that a reference methodology for the identification and quantification of African dust contributions should be adopted across Europe. PMID:24342088

Viana, M; Pey, J; Querol, X; Alastuey, A; de Leeuw, F; Lükewille, Anke

2014-02-15

64

Neutral Middle Atmospheric Influences by the Extremely Large October 2003 Solar Proton  

NASA Technical Reports Server (NTRS)

The huge coronal mass ejection (CME) on October 28, 2003 caused an extremely large solar proton event (SPE) 3t the Earth, which impacted the middle atmospheric polar cap regions. The highly energetic protons produce ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HO(x) (H, OH, HO2) and NO(y) (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The total production of middle atmospheric NO(y) molecules by individual SPEs can be used to compare their sizes. Using this scale, the extremely large October 2003 SPE was the fourth largest in the past 40 years and the second largest of solar cycle 23. Only the October 1989, August 1972, and July 2000 SPEs were larger. The Goddard Space Flight Center (CSFC) Two-dimensional (2D)) Model was used in computing the influence of this gigantic SPE The NO(y) amount was increased by over two orders of Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) measurements as a result of this noteworthy SPE. The model also calculated polar middle mesosphere ozone decreases of over 70% during the SPE. Other atmospheric impacts from both model predictions and measurements as a result of this major SPE will be discussed in this paper.

Jackman, C. H.; Fleming, E. L.

2004-01-01

65

Neutral Middle Atmospheric Influences by the Extremely Large October 2003 Solar Proton Event  

NASA Technical Reports Server (NTRS)

The huge coronal mass ejection (CME) on October 28,2003 caused an extremely large solar proton event (SPE) at the Earth, which impacted the middle atmospheric polar cap regions. The highly energetic protons produce ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The total production of middle atmospheric NOy molecules by individual SPEs can be used to compare their sizes. Using this scale, the extremely large October 2003 SPE was the fourth largest in the past 40 years and the second largest of solar cycle 23. Only the October 1989, August 1972, and July 2000 SPEs were larger. The Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model was used in computing the influence of this gigantic SPE. The NOy amount was increased by over two orders of magnitude in the mesosphere in both the GSFC 2D Model computations and Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) measurements as a result of this noteworthy SPE. The model also calculated polar middle mesospheric ozone decreases of over 70% during the SPE. Other atmospheric impacts from both model predictions and measurements as a result of this major SPE will be discussed in this paper.

Jackman, C. H.; Fleming, E. L.

2004-01-01

66

The influence of surface atmospheric conditions on the range and area reached by animal vocalizations.  

PubMed

Low-level vertical changes in temperature and wind exert powerful and predictable influences on the area ensonified by animal vocalizations. Computer modelling of low-frequency sound propagation in measured atmospheric conditions predicts that the calls of the savanna elephant at these frequencies can have ranges exceeding 10 km and that the calls will be highly directional in the presence of wind shear. Calling area is maximized under temperature inversions with low wind speeds. Calling area changes substantially over 24 h periods; on any given day, the calling area undergoes an expansion and contraction which may be as large as one order of magnitude. This cycle is modulated by topography, regional weather patterns, seasonality and possibly by climate variation. Similar influences affect the somewhat higher-frequency calls of lions and may be a selective pressure towards their crepuscular and nocturnal calling behaviour. Coyotes and wolves, which also live in areas with strong and prevalent nocturnal temperature inversions, show similar calling patterns, maximizing their chances of being heard over the longest possible distances. The pronounced dawn and evening vocalization peaks in other animals including birds, frogs and insects may reflect the same influences in combination with other factors which selectively limit high-frequency sound propagation. Atmospheric conditions therefore need to be taken into account in many field studies of animal behaviour. A simplified method for estimating sound propagation during field studies is presented. PMID:9057305

Larom, D; Garstang, M; Payne, K; Raspet, R; Lindeque, M

1997-02-01

67

A trajectory climatology for Svalbard; investigating how atmospheric flow patterns influence observed tracer concentrations  

NASA Astrophysics Data System (ADS)

A 10-year climatology of long-range atmospheric transport to Ny-Ålesund, Svalbard (78.9°N, 11.9°E) is developed using three-dimensional 5-day back-trajectories. We calculate trajectories arriving twice daily at 950, 850 and 750 hPa during 1992-2001, using European Centre for Medium-Range Weather Forecasts (ECMWF) analyzed wind fields. Cluster analysis is used to classify the trajectories into distinct transport patterns. The clustering procedure is performed on the whole 10-year set of trajectories, to study both year-to-year and month-to-month variability in the synoptic-scale atmospheric circulation. We identify eight major transport patterns to Ny-Ålesund, which we find to be consistent with mean-pressure charts of the Arctic region. The distribution of trajectories between these flows is similar for all years during the 10-year period. However, there are seasonal differences in when different clusters are most prevalent. The calculated clusters provide an indication of source regions and transport pathways influencing Svalbard at different times of the year. Such information is valuable for interpreting measured time-series of trace gases and aerosols and could serve as guidance for formulating sampling strategies. We compare the trajectory clusters to CO 2 measurements to study to what degree different atmospheric flow patterns influence the variability of the atmospheric CO 2. Overall we see a linkage between CO 2 concentration and the large-scale circulation. For instance, in connection with transport over Europe and Siberia during winter, high CO 2 mixing ratios are observed, whereas trajectories originating from the Atlantic are associated with low CO 2 concentrations. However, during some periods and for some individual trajectories we see no conclusive linkage between variability in atmospheric CO 2 and transport. This can be due to a combination of the complex structure of CO 2 sources and sinks and its relatively long atmospheric turn-over time. CO 2 and 222Rn mixing ratios are calculated using the three-dimensional transport model MATCH to further illustrate these characteristics of CO 2.

Eneroth, Kristina; Kjellström, Erik; Holmén, Kim

68

Modern and historic atmospheric mercury fluxes in both hemispheres: Global and regional mercury cycling implications  

NASA Astrophysics Data System (ADS)

Using two different natural archiving media from remote locations, we have reconstructed the atmospheric deposition of mercury (Hg) over the last 800-1000 years in both hemispheres. This effort was designed (1) to quantify the historical variation and distributional patterns of atmospheric Hg fluxes in the midlatitudes of North America at Nova Scotia (N.S.) and at a comparable midlatitude region in the Southern Hemisphere at New Zealand (N.S.), (2) to identify and quantify the influence of anthropogenic and natural Hg contributions to atmospheric Hg fluxes, (3) to further investigate the suitability and comparability of our two selected media (lake sediments and ombrotrophic peat) for Hg depositional reconstructions, and (4) to assess the relative importance of wet and dry deposition to the study areas. Significant findings from the study include the following: (1) The lake sediments examined appear to faithfully record the contemporary flux of Hg from the atmosphere (e.g., 1997: N.S. Lakes: approximately 8 ± 3 ?g m-2 yr-1; N.S. Rain: 8 ?g m-2 yr-1). The upper 10 cm (approximately 10 yr) of ombrotrophic peat cores from Nova Scotia were dated using a biological chronometer (Polytrichum) and were also consistent with the flux data provided by current direct sampling of precipitation. These observations place limits on the contribution of dry deposition (40 ± 50% of wet flux). Unfortunately, the peat samples could not be dated below 10 cm. This was due to the apparent diagenetic mobility of the geochronological tracer (210Pb). (2) There is no evidence of a significant enhancement in the atmospheric Hg flux as a result of preindustrial (<1900 c.e. (Common Era)) activities such as the extensive Au and Ag mining in the Americas. (3) A factor of 3 and 5x increase in the deposition of Hg to the lake sediment archives was observed since the advent of the industrial revolution in New Zealand and Nova Scotia respectively, suggesting a worldwide increase in the atmospheric deposition of Hg. Furthermore, this increase is synchronous with increases in the release of CO2 from combustion of fossil fuels on a global scale. The magnitude of increase since industrialization appears larger in Nova Scotia than in New Zealand. This may be due to enhanced deposition of Hg as a result of either regional emission of Hg or enhanced regional oxidation of Hg°.

Lamborg, C. H.; Fitzgerald, W. F.; Damman, A. W. H.; Benoit, J. M.; Balcom, P. H.; Engstrom, D. R.

2002-12-01

69

Regional influence of a small lake on lake-breeze formation, atmospheric circulation and cloud formation, using ARMOR and MAX radar observations and dual Doppler analysis of three dimensional wind fields  

NASA Astrophysics Data System (ADS)

The presented study reports the analysis of radar observations of the lake breeze front from a small lake. The ARMOR (Advanced Radar for Meteorological and Operational Research) facility at Huntsville International Airport is located about 30 km distance from the lake. ARMOR observations showed that during synoptic conditions of low wind and high pressure, a lake-breeze circulation forced by Wheeler Reservoir generates significant flow perturbations in the convective boundary layer which sometimes are significant enough to produce convective initiation, cloud formation and precipitation. Close investigation of archived ARMOR observations of May 2005, 2006 and 2007 showed that lake-breeze fronts may be develop either on the north or the south side of Wheeler Lake, and occasionally on both sides. Sometimes the lake breeze develops mesoscale circulations along the lake that trace the detailed shape of the lake, and other times circulations develop in scattered patches. Sometimes the lake breeze persists for extended periods of time, sometimes it appears to be stationary, other times it advects away, and sometimes convective initiation is followed by cumulus cloud formation and precipitation. The goal was to understand the reasons for these various scenarios. ARMOR radar radial velocity measurements provided the means to understand the various aspects of the lake-breeze front development and dissipation. Specifically, the lake-breeze formation, size, orientation, strength and stability have a direct association with the direction and strength of the background wind versus the orientation of the lake as well as temperature gradient. In order to better understand the behavior of the boundary layer during such atmospheric activities, we performed two days of field measurements in the summer of 2008 using MAX (Mobile Alabama X-Band) radar, MIPS (Mobile Integrated Profiling System) and the M3V (Mobile Meteorological Measurements Vehicle) provided by the University of Alabama in Huntsville. On June 10th we captured the lake breeze boundaries on both shores, cumulus cloud formation as well as convective initiation. MIPS measurements were used for better understanding of the BL evolution during the passage of the lake breeze. Observations of MAX radar were coupled with ARMOR for dual Doppler analysis and a 3-dimensional wind field of the lake breeze circulations was developed that provided information on kinematic and dynamic evolution of the lake breeze.

Asefi-Najafabady, Salvi

70

Atmospheric Mercury in the Great Lakes Region An Evaluation of the Community Multiscale Air Quality  

E-print Network

Atmospheric Mercury in the Great Lakes Region An Evaluation of the Community Multiscale Air Quality Tracey Holloway #12;i Abstract Atmospheric mercury is a significant source for methylmercury (Me. In order to control MeHg exposures, policy-makers need a clear understanding of the atmospheric mercury

Wisconsin at Madison, University of

71

Influence of solar activity on middle atmosphere associated with phases of equatorial quasi-biennial oscillation  

NASA Technical Reports Server (NTRS)

Earlier studies on the influence of solar activity variations within a 11-year solar cycle on temperature changes in the middle atmosphere revealed that while the temperature in the mesosphere showed strong responses to changes in solar activity, the stratosphere remained almost unaffected. Recent studies showed that when the temperature data were grouped into east or west phase of the equatorial quasi-biennial oscillation (QBO) in stratospheric zonal wind, significant relationships of temperature in the lower stratosphere and troposphere could be obtained with 10.7 cm solar radio flux. Positive correlations in high latitude regions and negative correlations in mid-latitude and tropical regions were obtained during winter when the QBO was in its west phase. During the east phase, converse relationships were indicated. These results inspired this study on the response of solar activity in 11-year cycle on the temperature structure of the middle atmosphere in the two phases of equatorial QBO of zonal wind at 50 mb, in tropics, mid-latitude and antarctic regions.

Mohanakumar, K.

1989-01-01

72

Rare earth element components in atmospheric particulates in the Bayan Obo mine region.  

PubMed

The Bayan Obo mine, located in Inner Mongolia, China, is the largest light rare earth body ever found in the world. The research for rare earth elements (REEs) enrichment in atmospheric particulates caused by mining and ore processing is fairly limited so far. In this paper, atmospheric particulates including total suspended particulate (TSP) matter and particles with an equivalent aerodynamic diameter less than 10 ?m (PM10) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m(3), and those for PM10 were 42.8 and 68.9 ng/m(3), in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM10 and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM10 were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N), Gd(N)/Yb(N)). PMID:24657942

Wang, Lingqing; Liang, Tao; Zhang, Qian; Li, Kexin

2014-05-01

73

Regional scale evaporation and the atmospheric boundary layer  

NASA Technical Reports Server (NTRS)

In this review we briefly summarize some current models of evaporation and the atmospheric boundary layer (ABL) and discuss new experimental and computational oppurtunities that may aid our understanding of evaporation at these larger scales. In particular, consideration is given to remote sensing of the atmosphere, computational fluid dynamics and the role numerical models can play in understanding land-atmosphere interactions. These powerful modeling and measurement tools are allowing us to visualize and study spatial and temporal scales previously untouched, thereby increasing the oppurtunities to improve our understanding of land-atmosphere interaction.

Parlange, Marc B.; Eichinger, William E.; Albertson, John D.

1995-01-01

74

Summer temperature extremes in northeastern Spain: spatial regionalization and links to atmospheric circulation (1960-2006)  

NASA Astrophysics Data System (ADS)

A procedure for classifying daily summer temperature extremes in northeastern Spain into homogenous regions has been presented and evaluated. This procedure employed daily temperature series from a dense network of 128 weather stations spanning the period from 1960 to 2006. Characteristics of temperature extremes included temperature frequency (e.g., warm days), intensity (e.g., warmest day), and duration (e.g., maximum length of hot spell). Following the results of the principal components analysis and Ward's method of clustering, the study area was divided into four homogenous sub-regions in terms of both the geographic and climatic meanings: the Mediterranean region, the mainland and the Cantabrian region, the moderately elevated areas westward and southward, and the mountainous region. Based on an internal cluster validation measure (Silhouette width), the quality of clustering was evaluated and ensured. The temporal evolution of the long-term (1960-2006) temperature extremes clearly showed a different behavior amongst these sub-regions. The Mediterranean and the highly elevated regions revealed the strongest signals in both daytime and nighttime extremes. For mainland areas, considerable differences in the behavior of the daytime and nighttime temperature extremes were evident. The influence of atmospheric circulation on spatial and temporal variability of temperature extremes was also explored. The variability of summer temperature extremes in NE Spain appears to be mainly driven by the Scandinavian (SCA), the Western Mediterranean Oscillation (WeMO), and the East Atlantic (EA) patterns, with a tendency toward increasing during the positive (negative) phases of the EA (WeMO and SCA) circulation modes. In such a region with complex geography and climate, regionalization of summer temperature extremes can be advantageous for extracting finer-scale information, which may prove useful for the vulnerability assessments and the development of local adaptation strategies in areas such as health, ecosystems and agriculture.

El Kenawy, Ahmed; López-Moreno, Juan I.; Vicente-Serrano, Sergio M.

2013-08-01

75

Roles of atmospheric and land surface data in dynamic regional downscaling  

E-print Network

Roles of atmospheric and land surface data in dynamic regional downscaling Deepak K. Ray,1,2 Roger in dynamic regional downscaling, J. Geophys. Res., 115, D05102, doi:10.1029/2009JD012218. 1. Introduction [2

Niyogi, Dev

76

Influence of a Carrington-like event on the atmospheric chemistry, temperature and dynamics: revised  

NASA Astrophysics Data System (ADS)

This study investigates the influence of a major solar proton event (SPE) similar to the Carrington event of 1-2 September 1859 by means of the 3D chemistry climate model (CCM) SOCOL v2.0. Ionization rates were parameterized according to CRAC:CRII (Cosmic Ray-induced Atmospheric Cascade: Application for Cosmic Ray Induced Ionization), a detailed state-of-the-art model describing the effects of SPEs in the entire altitude range of the CCM from 0 to 80 km. This is the first study of the atmospheric effect of such an extreme event that considers all the effects of energetic particles, including the variability of galactic cosmic rays, in the entire atmosphere. We assumed two scenarios for the event, namely with a hard (as for the SPE of February 1956) and soft (as for the SPE of August 1972) spectrum of solar particles. We have placed such an event in the year 2020 in order to analyze the impact on a near future atmosphere. We find statistically significant effects on NOx, HOx, ozone, temperature and zonal wind. The results show an increase of NOx of up to 80 ppb in the northern polar region and an increase of up to 70 ppb in the southern polar region. HOx shows an increase of up to 4000%. Due to the NOx and HOx enhancements, ozone reduces by up to 60% in the mesosphere and by up to 20% in the stratosphere for several weeks after the event started. Total ozone shows a decrease of more than 20 DU in the northern hemisphere and up to 20 DU in the southern hemisphere. The model also identifies SPE induced statistically significant changes in the surface air temperature, with warming in the eastern part of Europe and Russia of up to 7 K for January.

Calisto, M.; Usoskin, I.; Rozanov, E.

2013-12-01

77

Atmospheric teleconnection mechanisms of extratropical North Atlantic SST influence on Sahel rainfall  

NASA Astrophysics Data System (ADS)

Extratropical North Atlantic cooling has been tied to droughts over the Sahel in both paleoclimate observations and modeling studies. This study, which uses an atmospheric general circulation model (GCM) coupled to a slab ocean model that simulates this connection, explores the hypothesis that the extratropical North Atlantic cooling causes the Sahel droughts via an atmospheric teleconnection mediated by tropospheric cooling. The drying is also produced in a regional climate model simulation of the Sahel when reductions in air temperature (and associated geopotential height and humidity changes) from the GCM simulation are imposed as the lateral boundary conditions. This latter simulation explicitly demonstrates the central role of tropospheric cooling in mediating the atmospheric teleconnection from extratropical North Atlantic cooling. Diagnostic analyses are applied to the GCM simulation to infer teleconnection mechanisms. An analysis of top of atmosphere radiative flux changes diagnosed with a radiative kernel technique shows that extratropical North Atlantic cooling is augmented by a positive low cloud feedback and advected downstream, cooling Europe and North Africa. The cooling over North Africa is further amplified by a reduced greenhouse effect from decreased atmospheric specific humidity. A moisture budget analysis shows that the direct moisture effect and monsoon weakening, both tied to the ambient cooling and resulting circulation changes, and feedbacks by vertical circulation and evaporation augment the rainfall reduction. Cooling over the Tropical North Atlantic in response to the prescribed extratropical cooling also augments the Sahel drying. Taken together, they suggest a thermodynamic pathway for the teleconnection. The teleconnection may also be applicable to understanding the North Atlantic influence on Sahel rainfall over the twentieth century.

Liu, Yuwei; Chiang, John C. H.; Chou, Chia; Patricola, Christina M.

2014-11-01

78

Simulation of atmospheric dynamics and air quality in the Baikal region  

NASA Astrophysics Data System (ADS)

The results of scenario estimation of summer conditions for the formation of atmospheric circulations and transport of pollutants of natural and anthropogenic origin in the Baikal region atmosphere and over the Baikal water area are presented. Possible changes in air quality are studied with a mesoscale nonhydrostatic model of atmospheric dynamics and pollutant transport. The investigation has revealed some meteorological situations that are unfavorable for air quality in the Baikal region and over its water area.

Pyanova, Elza A.; Penenko, Vladimir V.; Faleychik, Larisa M.

2014-11-01

79

Precipitation extremes in the wettest Mediterranean region (Krivošije) and associated atmospheric circulation types  

NASA Astrophysics Data System (ADS)

The aim of this paper is to analyse indices of extreme precipitation in Krivošije, Montenegro, the wettest Mediterranean region, from the period 1951-2007 and their relationships with atmospheric circulation using "SynopVis Grosswetterlagen" (SVG) series. Data from two stations were analysed, namely Crkvice (42°34'N and 18°39'E) and Herceg Novi (42°27'N and 18°31'E). Four indices of precipitation extremes (SDII, R75p, R95p, R95pTOT) were assessed including number of dry days. The results suggest that the number of days with precipitation decreased. To analyse the relationship between extreme precipitation events and circulation types we have used an efficiency coefficient (Ec). Regarding relation to atmospheric circulation, westerly, southwesterly and northwesterly circulation types with anticyclonic features over Central Europe are more frequent for dry days (days with R<1.0 mm) and northerly, easterly and southerly types for wet and very wet days (R75p and R95p indices). The types with cyclonic condition over Central Europe show a large proportion of wet and very wet days. Also, activity of Genoa cyclogenesis and orographic influence over a small area are the main reasons for the high precipitation amounts recorded in the Krivošije region (Crkvice).

Duci?, V.; Lukovi?, J.; Buri?, D.; Stanojevi?, G.; Mustafi?, S.

2012-03-01

80

East African food security as influenced by future climate change and land use change at local to regional scales  

Microsoft Academic Search

Climate change impacts food production systems, particularly in locations with large, vulnerable populations. Elevated greenhouse\\u000a gases (GHG), as well as land cover\\/land use change (LCLUC), can influence regional climate dynamics. Biophysical factors such\\u000a as topography, soil type, and seasonal rainfall can strongly affect crop yields. We used a regional climate model derived\\u000a from the Regional Atmospheric Modeling System (RAMS) to

Nathan Moore; Gopal Alagarswamy; Bryan Pijanowski; Philip Thornton; Brent Lofgren; Jennifer Olson; Jeffrey Andresen; Pius Yanda; Jiaguo Qi

2012-01-01

81

Influence of different propagation paths on the propagation of laser in atmospheric turbulence  

NASA Astrophysics Data System (ADS)

The analytical expressions for the average intensity, root mean square (RMS) beam width and angular spread of Gaussian Schell-model (GSM) beams propagating under slant atmospheric turbulence are derived, and they are used to study the influence of different propagation paths on the propagation of laser beams in atmospheric turbulence. It is shown that under the same condition, the influence of atmospheric turbulence along a downlink path on the GSM beam propagation is the smallest among the three paths. Therefore, the downlink propagation is more beneficial to the beam propagation through atmospheric turbulence compared with the uplink propagation and horizontal propagation.

Duan, Mei-ling; Li, Jin-hong; Wei, Ji-lin

2013-11-01

82

A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms  

NASA Astrophysics Data System (ADS)

We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 predictions generally agree better with the observed data than the CB05TU predictions. RACM2 enhances ozone for all ambient levels leading to higher bias at low (< 60 ppbv) concentrations but improved performance at high (>70 ppbv) concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. While RACM2 enhances ozone and secondary aerosols by relatively large margins, control strategies developed for ozone or fine particles using the two mechanisms do not differ appreciably.

Sarwar, G.; Godowitch, J.; Henderson, B.; Fahey, K.; Pouliot, G.; Hutzell, W. T.; Mathur, R.; Kang, D.; Goliff, W. S.; Stockwell, W. R.

2013-03-01

83

A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms  

NASA Astrophysics Data System (ADS)

We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 enhances ozone compared to CB05TU at all ambient levels. Although it exhibited greater overestimates at lower observed concentrations, it displayed an improved performance at higher observed concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. Any air pollution control strategies developed using the two mechanisms do not differ appreciably.

Sarwar, G.; Godowitch, J.; Henderson, B. H.; Fahey, K.; Pouliot, G.; Hutzell, W. T.; Mathur, R.; Kang, D.; Goliff, W. S.; Stockwell, W. R.

2013-10-01

84

Atmospheric profiles of CO? as integrators of regional scale exchange   

E-print Network

The global climate is changing due to the accumulation of greenhouse gases (GHGs) in the atmosphere, primarily due to anthropogenic activity. The dominant GHG is CO? which originates from combustion of fossil fuels, land use change and management...

Smallman, Thomas Luke

2014-06-30

85

The influence of scales of atmospheric motion on air pollution over Portugal  

NASA Astrophysics Data System (ADS)

Air pollution is determined by the combination of different factors, namely, emissions, physical constrains, meteorology and chemical processes [1,2,3]. The relative importance of such factors is influenced by their interaction on diverse scales of atmospheric motion. Each scale depicts different meteorological conditions, which, when combined with the different air pollution sources and photochemistry, result in varying ambient concentrations [2]. Identifying the dominant scales of atmospheric motion over a given airshed can be of great importance for many applications such as air pollution and pollen dispersion or wind energy management [2]. Portugal has been affected by numerous air pollution episodes during the last decade. These episodes are often related to peak emissions from local industry or transport, but can also be associated to regional transport from other urban areas or to exceptional emission events, such as forest fires. This research aims to identify the scales of atmospheric motion which contribute to an increase of air pollution. A method is proposed for differentiating between the scales of atmospheric motion that can be applied on a daily basis from data collected at several wind-measuring sites in a given airshed and to reanalysis datasets. The method is based on the daily mean wind recirculation and the mean and standard deviation between sites. The determination of the thresholds between scales is performed empirically following the approach of Levy et al. [2] and also through a automatic statistical approach computed taking into account the tails of the distributions (e.g. 95% and 99% percentile) of the different wind samples. A comparison is made with two objective approaches: 1) daily synoptic classification for the same period over the region [4] and 2) a 3-D backward trajectory approach [5,6] for specific episodes. Furthermore, the outcomes are expected to support the Portuguese authorities on the implementation of strategies for a sustainable management of environmental risks. [1] Demuzere, M., Trigo, R.M., Vila-Guerau de Arellano, van Lipzig, N.P.M., 2009. The impact of weather and atmospheric circulation on O3 and PM10 levels at a rural mid-latitude site. Atmos. Chem. Phys., 9, 2695-2714. [2] Levy, I., Dayan, U., Mahrer, Y., 2009. Differing atmospheric scales of motion and their impact on air pollutants. Int. J. Climatol. [3] Pearce, J., Beringer, J., Nicholls, N., Hyndman, R.J., Uotila, P., Tapper, N.J., 2011. Investigating the influence of synoptic-scale meteorology on air quality using self-organizing maps and generalized additive modeling. Atmospheric Environment, 45, 1, 128 - 136, doi 10.1016/j.atmosenv.2010.09.032. [4 Trigo, R.M., DaCamara, C.C., 2000. Circulation Weather Types and their impact on the precipitation regime in Portugal. Int. J. Climat., 20, 1559-1581. [5] Carvalho, A., Monteiro, A., Ribeiro, I., Tchepel, O., Miranda, A.I., Borrego, C., Saavedra, S., Souto, J.A., Casares, J.J., 2010. High ozone levels in the Northeast of Portugal: analysis and characterization. Atmospheric Environment, 44, 1020 - 1031. [6] Saavedra, S., Rodríguez, A., Taboada, J.J., Souto, J.A., Casares, J.J., 2012. Synoptic patterns and air mass transport during ozone episodes in northwestern Iberia. Sci Total Environ., 441, 97-110. doi: 10.1016/j.scitotenv.2012.09.014.

Russo, Ana; Trigo, Ricardo; Mendes, Manuel; Jerez, Sonia; Gouveia, Célia Marina

2014-05-01

86

Atmospheric Rivers Induced Heavy Precipitation and Flooding in the Western U.S. Simulated by the WRF Regional Climate Model  

SciTech Connect

Twenty years of regional climate simulated by the Weather Research and Forecasting model for North America has been analyzed to study the influence of the atmospheric rivers and the role of the land surface on heavy precipitation and flooding in the western U.S. Compared to observations, the simulation realistically captured the 95th percentile extreme precipitation, mean precipitation intensity, as well as the mean precipitation and temperature anomalies of all the atmospheric river events between 1980-1999. Contrasting the 1986 President Day and 1997 New Year Day atmospheric river events, differences in atmospheric stability are found to have an influence on the spatial distribution of precipitation in the Coastal Range of northern California. Although both cases yield similar amounts of heavy precipitation, the 1997 case was found to produce more runoff compared to the 1986 case. Antecedent soil moisture, the ratio of snowfall to total precipitation (which depends on temperature), and existing snowpack all seem to play a role, leading to a higher runoff to precipitation ratio simulated for the 1997 case. This study underscores the importance of characterizing or simulating atmospheric rivers and the land surface conditions for predicting floods, and for assessing the potential impacts of climate change on heavy precipitation and flooding in the western U.S.

Leung, Lai R.; Qian, Yun

2009-02-12

87

The influence of atmospheric scattering on imaging of Titan's surface  

NASA Astrophysics Data System (ADS)

In the visible and near-infrared wavelength range (500--1000 nm), the optical thickness of Titan's atmosphere generally varies between about 0.5 and 4, although it can be much higher in methane absorption bands. This has two effects on the radiance as measured from outside the atmosphere. First, the illumination of the surface is strongly wavelength dependent because of methane absorption bands. Second, the direct radiance coming upward from the surface is attenuated due to atmospheric extinction, and a diffuse component due to scattering by the atmosphere is added. We assess both effects by radiative transfer computations based on a microphysical model for aerosol formation. Taking into account scattering by aerosol particles, Rayleigh scattering by nitrogen, and methane absorption, we simulate spectra as observed from outside the atmosphere. The modeled radiances can be used to subtract the atmospheric component from observed images or spectra and to correct for the wavelength dependent illumination. The Descent Imager/Spectral Radiometer (DISR) aboard the Huygens probe will provide in situ measurements of the optical properties during its descent through Titan's atmosphere. Radiative transfer computations based on DISR measurements will make the correction procedure independent of a priori assumptions.

Grieger, B.; Schröder, S.; Rodin, A. V.

88

The Influence of Solar Proton Events in Solar Cycle 23 on the Neutral Middle Atmosphere  

NASA Technical Reports Server (NTRS)

Solar proton events (SPEs) can cause changes in constituents in the Earth's middle atmosphere. The highly energetic protons cause ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HO(x) (H, OH, HO2) and NO(y) (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HO(x) increases lead to short-lived ozone decreases in the mesosphere and upper stratosphere due to the short lifetimes of the HO, constituents. The NO(x) increases lead to long-lived stratospheric ozone changes because of the long lifetime of NO(y) constituents in this region. Solar cycle 23 was quite active with SPEs and very large fluxes of high energy protons occurred in July and November 2000, November 200 1, and April 2002. Smaller, but still substantial, proton fluxes impacted the Earth during other months in the 1997-2003 time period. The impact of the very large SPEs on the neutral middle atmosphere during solar cycle 23 will be discussed, including the HO(x), NO(y), ozone variations and induced atmospheric transport changes. Two multi-dimensional models, the Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model and the Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM), were used in computing the influence of the SPEs. The results of the GSFC 2D Model and the TIME-GCM will be shown along with comparisons to the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments.

Jackman, Charles H.; vonKonig, Miriam; Anderson, John; Roble, Raymond G.; McPeters, Richard D.; Fleming, Eric L.; Russell, James M.

2004-01-01

89

The composition, spatial patterns, and influencing factors of atmospheric wet nitrogen deposition in Chinese terrestrial ecosystems.  

PubMed

Atmospheric nitrogen (N) deposition is an important component of the global N cycle, and is a key source of biologically available N. Understanding the spatio-temporal patterns and influencing factors of N deposition is essential to evaluate its ecological effects on terrestrial ecosystems, and to provide a scientific basis for global change research. In this study, we monitored the monthly atmospheric N deposition in rainfall at 41 stations from the Chinese Ecosystem Research Network through measuring total N (TN), total dissolved N (TDN), ammonium (NH4(+)-N), and nitrate (NO3(-)-N). The results showed that the atmospheric wet deposition of TDN, NH4(+)-N, and NO3(-)-N were 13.69, 7.25, and 5.93kgNha(-1)yr(-1), respectively. The deposition of TN and total particulate N (TPN) was 18.02 and 4.33kgNha(-1)yr(-1) respectively, in 2013. TPN accounted for 24% of TN, while NH4(+)-N and NO3(-)-N made up 40% and 33%, respectively, confirming the assumption that atmospheric wet N deposition would be underestimated without particulate N in rainfall. The N deposition was higher in Central and Southern China, and lower in North-west, North-east, Inner Mongolia, and Qinghai-Tibet regions. Precipitation, N fertilizer use, and energy consumption were significantly correlated with wet N deposition (all p<0.01). Models that included precipitation and N fertilizer can explain 80-91% of the variability in wet N deposition. Our findings reveal, for the first time, the composition of the wet N deposition in China at different scales and highlight the importance of TPN. PMID:25617702

Zhu, Jianxing; He, Nianpeng; Wang, Qiufeng; Yuan, Guofu; Wen, Ding; Yu, Guirui; Jia, Yanlong

2015-04-01

90

Spatial and temporal characteristics of urban atmospheric methane in Nagoya City, Japan:. an assessment of the contribution from regional landfills  

NASA Astrophysics Data System (ADS)

The spatial and temporal behavior of atmospheric methane (CH 4) in the Nagoya metropolitan area was investigated in relation to the regional meteorological and topographical characteristics. It was found that the daily maximum CH 4 concentrations in the central city area were observed when the northeast wind blew from the foothill of the northeastern mountainous area down into the central city areas, under stable atmospheric conditions. The large and active landfills are the major anthropogenic CH 4 sources and are located at the hill sites in the northeast. Therefore, it was considered that the air mass with the high concentration of CH 4 flowed from the landfill sites into the urban area, and exerted substantial influences on the spatial and temporal variations of atmospheric CH 4 concentrations in the central city area.

Ito, A.; Takahashi, I.; Nagata, Y.; Chiba, K.; Haraguchi, H.

91

Atmospheric influence on the deuterium excess signal in polar firn: implications for ice-core interpretation  

E-print Network

during most phase changes of water during its atmospheric cycle due to the different saturation vapourAtmospheric influence on the deuterium excess signal in polar firn: implications for ice, Princetonplein 5, NL-3584 CC Utrecht, The Netherlands ABSTRACT. The seasonal deuterium excess signal of fresh

Schlosser, Elisabeth

92

Coastal Zone Color Scanner atmospheric correction - Influence of El Chichon  

NASA Technical Reports Server (NTRS)

The addition of an El Chichon-like aerosol layer in the stratosphere is shown to have very little effect on the basic CZCS atmospheric correction algorithm. The additional stratospheric aerosol is found to increase the total radiance exiting the atmosphere, thereby increasing the probability that the sensor will saturate. It is suggested that in the absence of saturation the correction algorithm should perform as well as in the absence of the stratospheric layer.

Gordon, Howard R.; Castano, Diego J.

1988-01-01

93

On validation of regional atmosphere and wave models for the Black Sea region  

NASA Astrophysics Data System (ADS)

Mesoscale atmospheric models MM5 and WRF adapted to the Black Sea region in Marine Hydrophysical Institute (MHI, National Academy of Sciences of Ukraine) together with wave model WAM are widely using in the last decade. Black Sea meteorological and wave climate assessing, 3-5 days operational forecast, researches of various physical phenomena typical for the Black Sea coastal zone are examples of application of such regional model calculations. Therefore we made some inspection of their quality. Results of operational regional forecast of catastrophic weather events in the Black Sea region are considered. Flooding of 6-7 July 2012 in the Krasnodar Region, Russia caused a loss of more than 170 lives and huge economic damage. Hazardous storm of 11 November 2007 near the Crimean coast caused accidents and sinks of many vessels including ones carrying fuel oil and sulfur, more than 20 members of the crews were missing and severe ecological damage was suffered. However, the forecast of rainfall intensity had appeared five days before the flood at free access on the Internet website http://vao.hydrophys.org and the forecast of the wave height appeared on the same website three days before the storm. Quality of the regional forecast and its advantages over the global forecast are discussed. In situ wave data including 2D wave spectra obtained at the MHI Black Sea Research Platform in 2012-2013 over all seasons were compared with model calculations. The distance of the Platform to the shore is 0.5 km where the sea depth is 28 m. Only part of wave spectrum belonging to wave frequencies lower than 0.4 Hz was considered to filter out waves developing from the coastal line. It is concluded that scatter indexes for modeled significant wave height and mean frequency are about of 50% and 15%. Some systematic defects of model calculations are revealed but the use of the model-based forecasts could lead to significant reduction in human losses and economic damage from catastrophic weather events. The core support of this work was provided by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant Agreement 287844 for the project 'Towards COast to COast NETworks of marine protected areas (from the shore to the high and deep sea), coupled with sea-based wind energy potential (CoCoNet)'. The research leading to these results has also received funding from Ukrainian State Agency of Science, Innovations and Information under contracts F53/117-2013 and M/281-2013. Authors gratefully acknowledge continuing support of these foundations.

Dulov, Vladimir; Shokurov, Mikhail; Chechina, Katerina; Soukissian, Takvor; Malinovsky, Vladimir

2014-05-01

94

Regional spatial and temporal interpolation of atmospheric PCBs: Interpretation of Lake Michigan mass balance data  

SciTech Connect

During the Lake Michigan Mass Balance (LMMB) Project, over 600 atmospheric samples were collected at eight shoreline sites and during seven cruises. These samples were analyzed for persistent organic pollutants, including PCB congeners, atrazine, and trans-nonachlor. The authors have developed a method for interpreting the gas-phase data that includes fractionating the observed PCB concentration into land- and water-based sources. This approach accounts for differences in gas-phase atmospheric PCB concentration over water and over land. Using this fractionation approach, they have interpolated the measured data over time and space to predict PCB air concentrations over the lake during the LMMB field period. The results predict gas-phase {Sigma}PCB (sum of {approximately}98 congener groups) concentrations for each of 2,319 grid cells over the lake, on a monthly basis. The authors estimate that lake-wide monthly average {sigma}PCB gas-phase concentrations range from 0.136 to 1.158 ng/m{sup 3}, with an annual average PCB concentration of 0.457 ng/m{sup 3}. As expected, the highest concentrations of PCBs over the lake when the winds are from the southwest (out of the Chicago-Gary region) and when land surface temperatures are elevated. The predicted influence of Chicago is described on a monthly basis as a zone of elevated PCB concentrations for approximately 40 km into Lake Michigan.

Green, M.L.; Depinto, J.V.; Sweet, C.; Hornbuckle, K.C.

2000-05-01

95

A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry MechanismsChemistry Mechanisms  

EPA Science Inventory

We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RAC...

96

Medicanes in an ocean-atmosphere coupled regional climate model  

NASA Astrophysics Data System (ADS)

So-called medicanes (Mediterranean hurricanes) are meso-scale, marine and warm core Mediterranean cyclones which exhibit some similarities with tropical cyclones. The strong cyclonic winds associated with them are a potential thread for highly populated coastal areas around the Mediterranean basin. In this study we employ an atmospheric limited-area model (COSMO-CLM) coupled with a one-dimensional ocean model (NEMO-1d) to simulate medicanes. The goal of this study is to assess the robustness of the coupled model to simulate these extreme events. For this purpose 11 historical medicane events are simulated by the atmosphere-only and the coupled models using different set-ups (horizontal grid-spacings: 0.44o, 0.22o, 0.088o; with/with-out spectral nudging). The results show that at high resolution the coupled model is not only able to simulate all medicane events but also improves the simulated track length, warm core, and wind speed of simulated medicanes compared to atmosphere-only simulations. In most of the cases the medicanes trajectories and structures are better represented in coupled simulations compared to atmosphere-only simulations. We conclude that the coupled model is a suitable tool for systemic and detailed study of historical medicane events and also for future projections.

Akhtar, Naveed; Brauch, Jennifer; Ahrens, Bodo

2014-05-01

97

Medicanes in an ocean-atmosphere coupled regional climate model  

NASA Astrophysics Data System (ADS)

So-called medicanes (Mediterranean hurricanes) are meso-scale, marine, and warm-core Mediterranean cyclones that exhibit some similarities to tropical cyclones. The strong cyclonic winds associated with medicanes threaten the highly populated coastal areas around the Mediterranean basin. To reduce the risk of casualties and overall negative impacts, it is important to improve the understanding of medicanes with the use of numerical models. In this study, we employ an atmospheric limited-area model (COSMO-CLM) coupled with a one-dimensional ocean model (1-D NEMO-MED12) to simulate medicanes. The aim of this study is to assess the robustness of the coupled model in simulating these extreme events. For this purpose, 11 historical medicane events are simulated using the atmosphere-only model, COSMO-CLM, and coupled model, with different setups (horizontal atmospheric grid-spacings of 0.44°, 0.22°, and 0.08°; with/without spectral nudging, and an ocean grid-spacing of 1/12°). The results show that at high-resolution, the coupled model is able to not only simulate most of medicane events but also improve the track length, core temperature, and wind speed of simulated medicanes compared to the atmosphere-only simulations. The results suggest that the coupled model is more proficient for systemic and detailed studies of historical medicane events, and that this model can be an effective tool for future projections.

Akhtar, N.; Brauch, J.; Dobler, A.; Béranger, K.; Ahrens, B.

2014-03-01

98

Medicanes in an ocean-atmosphere coupled regional climate model  

NASA Astrophysics Data System (ADS)

So-called medicanes (Mediterranean hurricanes) are meso-scale, marine, and warm-core Mediterranean cyclones that exhibit some similarities to tropical cyclones. The strong cyclonic winds associated with medicanes threaten the highly populated coastal areas around the Mediterranean basin. To reduce the risk of casualties and overall negative impacts, it is important to improve the understanding of medicanes with the use of numerical models. In this study, we employ an atmospheric limited-area model (COSMO-CLM) coupled with a one-dimensional ocean model (1-D NEMO-MED12) to simulate medicanes. The aim of this study is to assess the robustness of the coupled model in simulating these extreme events. For this purpose, 11 historical medicane events are simulated using the atmosphere-only model, COSMO-CLM, and coupled model, with different setups (horizontal atmospheric grid spacings of 0.44, 0.22, and 0.08°; with/without spectral nudging, and an ocean grid spacing of 1/12°). The results show that at high resolution, the coupled model is able to not only simulate most of medicane events but also improve the track length, core temperature, and wind speed of simulated medicanes compared to the atmosphere-only simulations. The results suggest that the coupled model is more proficient for systemic and detailed studies of historical medicane events, and that this model can be an effective tool for future projections.

Akhtar, N.; Brauch, J.; Dobler, A.; Béranger, K.; Ahrens, B.

2014-08-01

99

Atmospheric correction analysis on LANDSAT data over the Amazon region. [Manaus, Brazil  

NASA Technical Reports Server (NTRS)

The Amazon Region natural resources were studied in two ways and compared. A LANDSAT scene and its attributes were selected, and a maximum likelihood classification was made. The scene was atmospherically corrected, taking into account Amazonic peculiarities revealed by (ground truth) of the same area, and the subsequent classification. Comparison shows that the classification improves with the atmospherically corrected images.

Parada, N. D. J. (principal investigator); Dias, L. A. V.; Dossantos, J. R.; Formaggio, A. R.

1983-01-01

100

Modern and historic atmospheric mercury fluxes in both hemispheres: Global and regional mercury cycling implications  

Microsoft Academic Search

Using two different natural archiving media from remote locations, we have reconstructed the atmospheric deposition of mercury (Hg) over the last 800–1000 years in both hemispheres. This effort was designed (1) to quantify the historical variation and distributional patterns of atmospheric Hg fluxes in the midlatitudes of North America at Nova Scotia (N.S.) and at a comparable midlatitude region in

C. H. Lamborg; W. F. Fitzgerald; A. W. H. Damman; J. M. Benoit; P. H. Balcom; D. R. Engstrom

2002-01-01

101

Modern and historic atmospheric mercury fluxes in both hemispheres: Global and regional mercury cycling implications  

Microsoft Academic Search

Using two different natural archiving media from remote locations, we have reconstructed the atmospheric deposition of mercury (Hg) over the last 8001000 years in both hemispheres. This effort was designed (1) to quantify the historical variation and distributional patterns of atmospheric Hg fluxes in the midlatitudes of North America at Nova Scotia (N.S.) and at a comparable midlatitude region in

C. H. Lamborg; W. F. Fitzgerald; A. W. H. Damman; J. M. Benoit; P. H. Balcom; D. R. Engstrom

2002-01-01

102

Modern and historic atmospheric mercury fluxes in both hemispheres: Global and regional mercury cycling implications  

Microsoft Academic Search

Using two different natural archiving media from remote locations, we have reconstructed the atmospheric deposition of mercury (Hg) over the last 800-1000 years in both hemispheres. This effort was designed (1) to quantify the historical variation and distributional patterns of atmospheric Hg fluxes in the midlatitudes of North America at Nova Scotia (N.S.) and at a comparable midlatitude region in

C. H. Lamborg; W. F. Fitzgerald; A. W. H. Damman; J. M. Benoit; P. H. Balcom; D. R. Engstrom

2002-01-01

103

Regional hydrologic consequences of increases in atmospheric CO2 and other trace gases  

Microsoft Academic Search

Concern over changes in global climate caused by growing atmospheric concentrations of carbon dioxide and other trace gases has increased in recent years as our understanding of atmospheric dynamics and global climate systems has improved. Yet despite a growing understanding of climatic processes, many of the effects of human-induced climatic changes are still poorly understood. Major alterations in regional hydrologic

Peter H. Gleick

1987-01-01

104

Large-Scale Atmospheric Forcing by Southeast Pacific Boundary-Layer Clouds: A Regional Model Study  

E-print Network

Large-Scale Atmospheric Forcing by Southeast Pacific Boundary-Layer Clouds: A Regional Model Study the radiative effect of boundary layer clouds over the Southeast Pacific on large-scale atmosphere circulation of the equator, and marine boundary layer stratocumulus clouds to the south. In a sensitivity experiment

Xie, Shang-Ping

105

Momentum Budget of the East Antarctic Atmospheric Boundary Layer: Results of a Regional Climate Model  

Microsoft Academic Search

Output of a regional atmospheric climate model is used to quantify the average January and July momentum budget of the atmospheric boundary layer (ABL) over the East Antarctic ice sheet and the surrounding oceans. Results are binned in nine elevation intervals over the ice sheet and six distance intervals over the ocean. In January, when surface cooling is weak, the

M. R. van den Broeke; N. P. M. van Lipzig; E. van Meijgaard

2002-01-01

106

Large-Scale Atmospheric Forcing by Southeast Pacific Boundary Layer Clouds: A Regional Model Study*  

E-print Network

Large-Scale Atmospheric Forcing by Southeast Pacific Boundary Layer Clouds: A Regional Model Study the radiative effect of boundary layer clouds over the southeast Pacific on large-scale atmosphere circulation of the equator, and marine boundary layer stratocumulus clouds to the south. In a sensitivity experiment

Wang, Yuqing

107

The cosmic ray primary composition at the knee region from lateral distributions of atmospheric C  

E-print Network

The cosmic ray primary composition at the knee region from lateral distributions of atmospheric C.40.De 96.40.Pq Keywords: Cosmic rays Extensive air showers Atmospheric C erenkov Chemical composition associated with extensive air showers to study the chemical composition of the primary cosmic rays

108

Solar activity influences on atmospheric electricity and on some structures in the middle atmosphere  

NASA Technical Reports Server (NTRS)

Only processes in the troposphere and the lower stratosphere are reviewed. General aspects of global atmospheric electricity are summarized in Chapter 3 of NCR (1986); Volland (1984) has outlined the overall problems of atmospheric electrodynamics; and Roble and Hays (1982) published a summary of solar effects on the global circuit. The solar variability and its atmospheric effects (overview by Donelly et al, 1987) and the solar-planetary relationships (survey by James et al. 1983) are so extremely complex that only particular results and selected papers of direct relevance or historical importance are compiled herein.

Reiter, Reinhold

1989-01-01

109

Regional forecasting with global atmospheric models; Fourth year report  

SciTech Connect

The scope of the report is to present the results of the fourth year`s work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals.

Crowley, T.J.; North, G.R.; Smith, N.R. [Applied Research Corp., College Station, TX (United States)

1994-05-01

110

TELEMEDICINE TO ASSIST PATIENT UNDERSTANDING OF ATMOSPHERIC INFLUENCE ON LUNG FUNCTION AND IMPROVE  

E-print Network

TELEMEDICINE TO ASSIST PATIENT UNDERSTANDING OF ATMOSPHERIC INFLUENCE ON LUNG FUNCTION AND IMPROVE-time generic telemedicine system is presented. It is discussed in the context of self- management for people as influencing lung function, we have used data collected during a feasibility study of the telemedicine system

McSharry, Patrick E.

111

Regional Assimilation of NASA Atmospheric Infrared Sounder (AIRS) Data  

NASA Technical Reports Server (NTRS)

The NASA Short-term Prediction Research and Transition (SPORT) Center seeks to accelerate the infusion of NASA Earth Science Enterprise (ESE) observations, data assimilation and modeling research into NW S forecast operations and decision-making. The Atmospheric Infrared Sounder (AIRS), is expected to advance climate research and weather prediction into the 21 st century. It is one of six instruments onboard Aqua, a satellite that is part of NASA s Earth Observing System. AIRS, along with two partner microwave sounding instruments, represents the most advanced atmospheric sounding system ever deployed in space. The system is capable of measuring the atmospheric temperature in the troposphere with radiosonde accuracies of 1 K over 1 km-thick layers under both clear and cloudy conditions, while the accuracy of the derived moisture profiles will exceed that obtained by radiosondes. It is imperative that the scientific community is prepared to take full advantage of next-generation satellite data that will become available within the next decade. The purpose of this paper is to describe a procedure designed to optimally assimilate AIRS data at high spatial resolution over both land and ocean. The assimilation system used in this study is the Local Analysis and Prediction System (LAPS) developed at the Forecast System Laboratory used extensively around the globe. Results will focus on quality control issues associated with AIRS, optimal assimilation strategies, and the impact of the AIRS data on subsequent numerical forecasts at 12 km produced by the next generation Weather Research and Forecast (WRF) model.

Chou, Shih-Hung; Lapenta, William; Jediovec, Gary J.; McCarty, William; Mecikalski, John R.

2004-01-01

112

Influence of hadron and atmospheric models on computation of cosmic ray ionization in the atmosphere-Extension to heavy nuclei  

NASA Astrophysics Data System (ADS)

In the last few years an essential progress in development of physical models for cosmic ray induced ionization in the atmosphere is achieved. The majority of these models are full target, i.e. based on Monte Carlo simulation of an electromagnetic-muon-nucleon cascade in the atmosphere. Basically, the contribution of proton nuclei is highlighted, i.e. the contribution of primary cosmic ray ?-particles and heavy nuclei to the atmospheric ionization is neglected or scaled to protons. The development of cosmic ray induced atmospheric cascade is sensitive to the energy and mass of the primary cosmic ray particle. The largest uncertainties in Monte Carlo simulations of a cascade in the Earth atmosphere are due to assumed hadron interaction models, the so-called hadron generators. In the work presented here we compare the ionization yield functions Y for primary cosmic ray nuclei, such as ?-particles, Oxygen and Iron nuclei, assuming different hadron interaction models. The computations are fulfilled with the CORSIKA 6.9 code using GHEISHA 2002, FLUKA 2011, UrQMD hadron generators for energy below 80 GeV/nucleon and QGSJET II for energy above 80 GeV/nucleon. The observed difference between hadron generators is widely discussed. The influence of different atmospheric parametrizations, namely US standard atmosphere, US standard atmosphere winter and summer profiles on ion production rate is studied. Assuming realistic primary cosmic ray mass composition, the ion production rate is obtained at several rigidity cut-offs - from 1 GV (high latitudes) to 15 GV (equatorial latitudes) using various hadron generators. The computations are compared with experimental data. A conclusion concerning the consistency of the hadron generators is stated.

Mishev, A. L.; Velinov, P. I. Y.

2014-12-01

113

Regional scale atmospheric dispersion simulation of accidental releases of radionuclides from Fukushima Dai-ichi reactor  

NASA Astrophysics Data System (ADS)

This paper presents the results of regional scale atmospheric dispersion simulation of accidental emission of radionuclides from the Fukushima Daiichi Reactor, Japan following the Tohoku earthquake and tsunami event on 11 March 2011. The objective was to study the temporal behaviour of plume trajectory, concentration, deposition and radiation dose pattern over an 80 km range around the reactor. The time-varying meteorological parameters during the release period were simulated with a multi-scale nested atmospheric model WRF ARW and the trajectory, plume dispersion were computed with Lagrangian Particle Dispersion models HYSPLIT, FLEXPART using the available information on accidental source term. The simulations indicated that the wind flow over Japan during the release period was driven by the large scale extra-tropical westerly waves and associated low pressure systems. In the lower levels, the flow was influenced by the local topography/sea breeze causing occasional landward wind shift on the east coast of Japan. Simulated airflow trajectories revealed that the plume stayed over the ocean by westerly winds on most days and the radioactivity dispersed over sea surface. Landward trajectories were found on a few days due to southeasterly, easterly and northeasterly flow (15-17, 19-21 March 2011) during which much of the radionuclides deposited over the land region. The hotspot of depositions occurred over east Pacific Ocean near to Japan. Over the land relatively high depositions were simulated in a narrow zone of 20 km width and 80 km length in the northwest sector in agreement with monitor data. Simulations showed wet depositions over the land to be higher than the dry depositions during 12-30 March due to occurrence of rainfall on some days. Comparison of activity deposition and air dose values with available observations confirmed that the plume pattern in a finer length scale around the site could be simulated realistically and agree with the measurements within the limitations of the uncertainty in source term.

Srinivas, C. V.; Venkatesan, R.; Baskaran, R.; Rajagopal, V.; Venkatraman, B.

2012-12-01

114

Influence of the El Niño-Southern Oscillation on the middle atmosphere temperature and ozone  

NASA Astrophysics Data System (ADS)

Using the middle atmosphere temperature dataset observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite experiment between 2002 and 2012, and temperatures simulated by the Whole Atmospheric Community Climate Model version 3.5 (WACCM3.5) between 1953 and 2005, we studied the influence of the El Niño-Southern Oscillation (ENSO) on middle atmosphere temperature and ozone during the Northern Hemisphere (NH) wintertime. Both temperature and ozone responses to ENSO observed by SABER show similar patterns to those simulated by the WACCM3.5 model. For the first time, a significant winter temperature response to ENSO in the middle mesosphere has been observed, with an anomalous warming of ~1.0 K/MEI (Multivariate ENSO Index) in the tropics and an anomalous cooling of ~-2.0 K/MEI in the NH middle latitudes. The observed temperature responses to ENSO in the mesosphere are opposite to those in the stratosphere, in agreement with previous modeling studies. In the lower stratosphere (below 30 km), the ozone response to ENSO is positively correlated with the temperature response, suggesting that the ENSO modulation of the residual mean meridional circulation primarily contributes to the lower stratosphere ozone response. While in the upper stratosphere (40-50 km), the ozone response to ENSO is anti-correlated with temperature in the tropics and middle latitudes, suggesting that the photochemical effects of adiabatic temperature changes play important roles in this region. But in the polar upper stratosphere, the ozone response simulated by the WACCM is again positively correlated with temperature, suggesting that the dynamical effect is dominant. Figure 1. Meridional cross section of the zonal mean temperature response to ENSO in winter derived from the WACCM3.5 simulation (left) and the SABER observational dataset (right). The contour interval is 0.2 K/MEI, the blue dash contour lines denote the negative values and the red solid contour lines denote positive values. The white regions indicate that the results are significant above 95% (1.96?) confidence level. Figure 2. As in Figure 1, but for the zonal mean ozone response to ENSO in winter between 20 and 60 km derived from the WACCM3 simulation (left) and the SABER observations (right). The ozone results are percentage variations with contour interval of 0.5%/MEI.

Li, T.; Calvo, N.; Yue, J.; Russell, J. M.; Smith, A. K.; Mlynczak, M. G.; She, C. Y.

2013-12-01

115

The Influence of High Aerosol Concentration on Atmospheric Boundary Layer Temperature Stratification  

SciTech Connect

Investigations of the changing in the atmospheric boundary layer (ABL) radiation balance as cased by natural and anthropogenic reasons is an important topic of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program. The influence of aerosol on temperature stratification of ABL while its concentration was extremely high within a long period of time was studied experimentally. The case was observed in Moscow region (Russia) with the transport of combustion products from peat-bog and forest fires in July-September, 2002. At this time the visibility was some times at about 100-300 m. Aerosol concentration measured by Moscow University Observatory and A.M. Obukhov Institute of Atmospheric Physics field station in Zvenigorod (55.7 N; 36.6 E) for several days was in 50-100 times more than background one (Gorchakov at al 2003). The high aerosol concentration can change the radiation balance at ABL, and so to change thermal stratification in ABL above the mega lopolis. For the analysis the data were used of synchronous measurements by MTP-5 (Microwave Temperature Profiler operating at wavelength 5 mm) in two locations, namely: downtown Moscow and country-side which is 50 km apart to the West (Zvenigorod station). (Kadygrov and Pick 1998; Westwater at al 1999; Kadygrov at al 2002). Zvenigorod station is located in strongly continental climate zone which is in between of the climates of ARM sites (NSANorth Slope of Alaska and SGP-Southern Great Plains). The town of Zvenigorod has little industry, small traffic volume and topography conductive to a good air ventilation of the town. For these reasons Zvenigorod can be considered as an undisturbed rural site. For the analysis some days were chosen with close meteorological parameters (average temperature, humidity, wind, pressure and cloud form) but strongly differing in aerosol concentration level.

Khaykin, M.N.; Kadygrove, E.N.; Golitsyn, G.S.

2005-03-18

116

Atmospheric fluxes of 210Pb to the western Mediterranean Sea and the Saharan dust influence  

Microsoft Academic Search

Pb 210 is a well known tracer of particle dynamics in the marine environment. Geochemical models partially rely on the knowledge of its atmospheric input. Unfortunately, this is poorly known in the western Mediterranean Sea, especially regarding long-term records. In this work we have evaluated the 210Pb annual atmospheric flux to this region from the analysis of 12 soil cores

J. Garcia-Orellana; J. A. Sanchez-Cabeza; P. Masqué; A. Àvila; E. Costa; M. D. Loÿe-Pilot; J. M. Bruach-Menchén

2006-01-01

117

Spectral transparency of the earth's atmosphere in the near-UV region  

NASA Astrophysics Data System (ADS)

The study reports high-resolution measurements of atmospheric spectral transparency in the near-UV region carried out in 1988-1989 at Terskol Peak in the central Caucasus using solar radiation observations. A method is suggested for separating the transparency values for atmospheric ozone and aerosol from the obtained data, and its applicability is discussed. It is shown that solar radiation measurements at zenith angles below 86 deg make it possible to separate the ozone, Rayleigh, and aerosol components from the general atmospheric transparency over the near-UV region.

Burlov-Vasil'Ev, K. A.; Vasil'Eva, I. E.

1992-12-01

118

Impacts of land-atmosphere coupling on regional rainfall and convection  

NASA Astrophysics Data System (ADS)

By analyzing rainfall events over four land-atmosphere coupling hotspot regions, the study assesses the need for adopting a dynamic coupling strength within the land surface model. The study aims to investigate the impacts of land-atmosphere coupling on mesoscale convection and rainfall over different hotspot regions. Impacts of land-atmosphere coupling are analyzed using Noah land model and Weather Research and Forecasting (WRF) model simulations over U.S. Southern Great Plains (SGP), Europe, northern India, and West Africa. The SGP stands out as a region of strong land-atmosphere coupling. While, over India and West Africa the default WRF model leads to too strong coupling effects. The results show improvements by adopting the dynamic coupling coefficient in simulating surface fluxes and resulting atmospheric state. For the four regions, the results indicate that the surface coupling coefficient does not affect the general location but could improve the intensity of the simulated precipitation. There is high uncertainty in land-atmosphere coupling and the results from this and prior studies need to be considered with caution. In particular, zones identified as coupling hotspots in climate studies and their coupling strength would likely change depending on the model formulations and coupling coefficient assigned. Results support the use of the dynamic coupling formulation for use in future studies but with a caution for use over complex terrains. Overall, these results highlight that evaluating and improving land-atmosphere coupling could potentially improve model performance across the globe.

Zheng, Yue; Kumar, Anil; Niyogi, Dev

2014-12-01

119

Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth  

NASA Astrophysics Data System (ADS)

Growth stimulation characteristics of plants seeds are investigated by an atmospheric discharge irradiation into plasma seeds. Atmospheric pressure plasma torch is consisted of alumina ceramics tube and the steel mesh electrodes wind inside and outside of the tube. When AC high voltage (8 kHz) is applied to the electrode gap, the barrier discharge plasma is produced inside the alumina ceramics tube. The barrier discharge plasma is blown outside with the gas flow in ceramics tube. Radish sprouts seeds locate at 1 cm from the torch edge. The growth stimulation was observed in the length of a stem and a root after the plasma irradiation. The stem length increases approximately 2.8 times at the cultivation time of 24 h. And the growth stimulation effect is found to be maintained for 40 h, after sowing seeds. The mechanism of the growth stimulation would be the redox reaction inside plant cells induced by oxygen radicals.

Akiyoshi, Yusuke; Hayashi, Nobuya; Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu

2011-11-01

120

The significance of the episodic nature of atmospheric deposition to Low Nutrient Low Chlorophyll regions  

NASA Astrophysics Data System (ADS)

the vast Low Nutrient Low-Chlorophyll (LNLC) Ocean, the vertical nutrient supply from the subsurface to the sunlit surface waters is low, and atmospheric contribution of nutrients may be one order of magnitude greater over short timescales. The short turnover time of atmospheric Fe and N supply (<1 month for nitrate) further supports deposition being an important source of nutrients in LNLC regions. Yet, the extent to which atmospheric inputs are impacting biological activity and modifying the carbon balance in oligotrophic environments has not been constrained. Here, we quantify and compare the biogeochemical impacts of atmospheric deposition in LNLC regions using both a compilation of experimental data and model outputs. A metadata-analysis of recently conducted field and laboratory bioassay experiments reveals complex responses, and the overall impact is not a simple "fertilization effect of increasing phytoplankton biomass" as observed in HNLC regions. Although phytoplankton growth may be enhanced, increases in bacterial activity and respiration result in weakening of biological carbon sequestration. The application of models using climatological or time-averaged non-synoptic deposition rates produced responses that were generally much lower than observed in the bioassay experiments. We demonstrate that experimental data and model outputs show better agreement on short timescale (days to weeks) when strong synoptic pulse of aerosols deposition, similar in magnitude to those observed in the field and introduced in bioassay experiments, is superimposed over the mean atmospheric deposition fields. These results suggest that atmospheric impacts in LNLC regions have been underestimated by models, at least at daily to weekly timescales, as they typically overlook large synoptic variations in atmospheric deposition and associated nutrient and particle inputs. Inclusion of the large synoptic variability of atmospheric input, and improved representation and parameterization of key processes that respond to atmospheric deposition, is required to better constrain impacts in ocean biogeochemical models. This is critical for understanding and prediction of current and future functioning of LNLC regions and their contribution to the global carbon cycle.

Guieu, C.; Aumont, O.; Paytan, A.; Bopp, L.; Law, C. S.; Mahowald, N.; Achterberg, E. P.; Marañón, E.; Salihoglu, B.; Crise, A.; Wagener, T.; Herut, B.; Desboeufs, K.; Kanakidou, M.; Olgun, N.; Peters, F.; Pulido-Villena, E.; Tovar-Sanchez, A.; Völker, C.

2014-11-01

121

Influence of local waste burning on atmospheric aerosol properties in urban environment  

NASA Astrophysics Data System (ADS)

Aerosols affect the radiative energy budget on both the regional and global scales. The wavelength-dependent aerosol optical depth (AOD) is a fundamental determinant of the amount by which extra-terrestrial incoming sunlight and outgoing terrestrial radiation are being attenuated in the atmosphere. The present study addresses the influence of local waste burning on aerosol characteristics, black carbon (BC) aerosol mass concentration and spectral solar irradiance using ground-based measurements over the tropical urban environment of Hyderabad, India. AOD has been observed to be maximum during burning days compared to normal days. Aerosol size spectra suggest bimodal distributions during pre-and post-burning periods and trimodal distributions during burning periods. Angstrom wavelength exponent estimated from spectral variation of AOD suggested dominance of accumulation mode particle loading during burning days compared to normal days. Diurnal variation of BC on normal days showed a broad nocturnal peak during ˜20:00 to ˜24:00 h with a maximum value of BC aerosol concentration of ˜14,000 ng m-3 whereas on local waste burning days enormous increases in BC concentrations have been observed with a peak at ˜60,000 ng m-3. Relative attenuation of global solar irradiance during burning days has been found to be of the order of 30% in the visible and 28% in the near-infrared regions. The results are discussed in detail in this paper.

Madhavi Latha, K.; Badarinath, K. V. S.

2006-03-01

122

Regional forecasting with global atmospheric models; Third year report  

SciTech Connect

This report was prepared by the Applied Research Corporation (ARC), College Station, Texas, under subcontract to Pacific Northwest Laboratory (PNL) as part of a global climate studies task. The task supports site characterization work required for the selection of a potential high-level nuclear waste repository and is part of the Performance Assessment Scientific Support (PASS) Program at PNL. The work is under the overall direction of the Office of Civilian Radioactive Waste Management (OCRWM), US Department of Energy Headquarters, Washington, DC. The scope of the report is to present the results of the third year`s work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain several studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals.

Crowley, T.J.; North, G.R.; Smith, N.R. [Applied Research Corp., College Station, TX (United States)

1994-05-01

123

Global atmospheric temperature distributions in the mesopause region  

NASA Astrophysics Data System (ADS)

The OSIRIS instrument on the Odin satellite has collected observations of the oxygen A-band airglow for some seven years, since the beginning of the Odin mission. The observations are made in the orbit plane and the spacecraft nods so that each limb scan provides a complete limb profile between 10 and 110 km, at the tangent point, of the A-band spectrum. This spectral feature switches from absorption at the lowest tangent altitudes to emission above 60 km tangent altitude. The quality of these A-band limb spectra is such that a single scan can be inverted to yield a temperature profile. As the satellite, which is a sun-synchronous orbit, covers the entire globe in a single day it is possible to derive global temperature profiles in the vicinity of the mesopause in a single day. In this paper the derived temperature profiles are presented and a global mesopause atmospheric temperature model is proposed.

Llewellyn, Edward J.; Degenstein, Doug; Gattinger, Richard; Bathgate, Anthony; Wilcox, Bradley

124

Atmospheric electricity coupling between earthquake regions and the ionosphere  

NASA Astrophysics Data System (ADS)

We propose a mechanism to explain suggested links between seismic activity and ionospheric changes detected overhead. Specifically, we explain changes in the natural extremely low-frequency (ELF) radio noise recently observed in the topside ionosphere aboard the DEMETER satellite at night, before major earthquakes. Our mechanism utilises increased electrical conductivity of surface layer air before a major earthquake, which reduces the surface-ionosphere electrical resistance. This increases the vertical fair weather current, and (to maintain continuity of electron flow) lowers the ionosphere. Magnitudes of crucial parameters are estimated and found to be consistent with observations. Natural variability in ionospheric and atmospheric electrical properties is evaluated, and may be overcome using a hybrid detection approach. Suggested experiments to investigate the mechanism involve measuring the cut-off frequency of ELF "tweeks", the amplitude and phase of very low frequency radio waves in the Earth-ionosphere waveguide, or medium frequency radar, incoherent scatter or rocket studies of the lower ionospheric electron density.

Harrison, R. G.; Aplin, K. L.; Rycroft, M. J.

2010-04-01

125

Numerical simulation of the marine atmospheric boundary layer flow over Cape Canaveral region and Gulf Stream using AVHRR SST: an atmospheric sea breeze model  

Microsoft Academic Search

An atmospheric mesoscale numerical model has been developed and applied to the marine atmospheric boundary layer in the vicinity of sharp sea-surface temperature (SST) gradients. The Gulf Stream offshore of Each Central Florida near Cape Canaveral is the region of interest. The model equations which govern atmospheric behavior are based on the basic conservation laws of mass, momentum, and energy.

Charles R. Bostater; Manuel Gimond; Erik Uhlhorn; Ted McNally

2000-01-01

126

Dynamical downscaling: Assessment of value retained and added using the Regional Atmospheric Modeling System (RAMS)  

E-print Network

Dynamical downscaling: Assessment of value retained and added using the Regional Atmospheric by dynamical downscaling is quantitatively evaluated by considering the spectral behavior of the Regional. For the particular case considered, dynamical downscaling with RAMS in RCM mode does not retain value of the large

Pielke, Roger A.

127

Dynamical downscaling: Assessment of value retained and added using the Regional Atmospheric Modeling System (RAMS)  

Microsoft Academic Search

The value restored and added by dynamical downscaling is quantitatively evaluated by considering the spectral behavior of the Regional Atmospheric Modeling System (RAMS) in relation to its domain size and grid spacing. A regional climate model (RCM) simulation is compared with NCEP Reanalysis data regridded to the RAMS grid at each model analysis time for a set of six basic

Christopher L. Castro; Roger A. Pielke; Giovanni Leoncini

2005-01-01

128

Influence of modified atmosphere packaging on 'star ruby' grapefruit phytochemicals.  

PubMed

Modified atmosphere packaging (MAP) can extend the shelf life of salads, vegetables, and fruits by generating a storage environment with low O2, high CO2, and high humidity. The current study investigates the effect of modified atmosphere and humidity generated by two plastic films, microperforated bags (MIPBs) and macroperforated bags (MAPBs), on the levels of phytochemicals present in 'Star Ruby' grapefruits (Citrus paradisi, Macf.) stored for 16 weeks at 10 °C. Control fruits were stored without any packaging film. Juice samples were analyzed every 4 weeks for ascorbic acid, carotenoids, limonoids, flavonoids, and furocoumarins and assessed for quality parameters. MAP significantly reduced weight loss compared to control grapefruits. Control fruits had more ?-carotene, lycopene, and furocoumarin compared with the fruits in MAP. Flavonoid content was highest in fruits stored in MAPB (P < 0.05), while fruits stored in MIPB showed no significant difference in flavonoid content compared to control (P > 0.05). The MAP treatments did not significantly affect ascorbic acid, limonoids, or fruit quality parameters, including total soluble solids, acidity, ripening ratio, decay and disorders, fruit taste, and off-flavors after 16 weeks of storage. These results suggest that MAP can be used to maintain the quality of 'Star Ruby' grapefruit with no detrimental effect on health-promoting phytochemicals. PMID:25547121

Chaudhary, Priyanka R; Jayaprakasha, G K; Porat, Ron; Patil, Bhimanagouda S

2015-01-28

129

The Influence of Tropospheric Processes in Modeling the Middle Atmosphere with Gravity Waves  

NASA Technical Reports Server (NTRS)

Our Numerical Spectral Model (NSM) extends from the ground up into the thermosphere and has a vertical grid point resolution of about 0.5 km to resolve the interactions of gravity waves (GWs) described with Hines' Doppler Spread Parameterization (DSP). This model produces in the stratosphere and mesosphere the major features of QBO, SAO, tides, and planetary waves. The purpose of this paper is to discuss results from an initial study with our 3D model that shows how certain tropospheric processes can affect the dynamics of the middle atmosphere. Under the influence of tropospheric heating, and augmented by GW interactions, two distinct but related processes can be identified. (1) A meridional circulation develops in the stratosphere, with rising motions at low latitudes that are in magnitude comparable to the downward propagation of the QBO. As Dunkerton pointed out, a larger GW source is then required to reproduce the observed QBO, which tends to move us closer to the values recommended for the DSP. This has significant consequences for our model results that describe the upper mesosphere, considering the general importance of GWs for this region and in influencing planetary waves (e.g., 2-day wave) and tides in particular. (2) Tropospheric heating produces zonal jets near the tropopause that are related to latitudinal variations in pressure and reversing temperature variations (resembling the dynamical conditions near the mesopause), which in turn is conducive to generate baroclinic instability. Modeling results show that our ability to generate the QBO critically depends on the magnitude of the temperature reversal that is a measure of this instability. Planetary waves are generated in this process, which can apparently interfere with or augment the GW interactions. As originally demonstrated by Lindzen and Holton, the eastward propagating Kelvin waves and westward propagating Rossby gravity waves (generated by tropospheric convection) can in principle provide the acceleration to influence the QBO, and we were able to confirm this with our 3D model.

Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Porter, H. S.

2002-01-01

130

Land conversion in Amazonia and Northern South America : influences on regional hydrology and ecosystem response  

E-print Network

A numerical model of the terrestrial biosphere (Ecosystem Demography Model) is compbined with an atmospheric model (Brazilian Regional Atmospheric Modeling System) to investigate how land conversion in the Amazon and ...

Knox, Ryan Gary

2013-01-01

131

The Influence of Atmospheric Transport Regimes on Polychlorinated Biphenyl (PCB) Concentrations Measured at Zeppelin  

NASA Astrophysics Data System (ADS)

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) of exclusively anthropogenic origin. PCBs are toxic, bioaccumulative and have a great potential of long-range transport. PCBs have been banned globally under the Stockholm convention on POPs since 2004. We analysed times series of 21 PCB congeners ranging from PCB 18 to PCB 187 that have been measured at Zeppelin (Spitsbergen) since 1993. Although primary PCB emissions have been steadily reduced, a strong decreasing trend is not observed in the PCB concentrations in the Arctic. In order to investigate the influence of atmospheric transport on the PCB concentrations and to identify the potential source regions of the PCBs, we calculated footprints for the Zeppelin measurement site using the Lagrangian Particle Dispersion Model FLEXPART. Footprints can be interpreted as potential source regions where PCBs may have been picked up. Based on various statistical analyses of the footprints (cluster analysis, k-medoid, silhouette), we identified the prevailing transport regimes for Zeppelin which were represented by 5 different clusters. Cluster 1 and 3 belong to transport regimes with highest residence times over Europe (cluster 1) and North-America (cluster 3); both transport regimes dominantly occur from late fall to early spring. Clusters 2 and 4 represent air masses with surface contact predominantly over the Atlantic Ocean (cluster 2), only occurring during the summer months, and the Arctic Ocean (cluster 4) mainly observed in spring and autumn, but also in summer. Cluster 5 is representative of air originating from the Pacific ocean and eastern Asia; this transport regime occurs mainly in spring and fall. We grouped the PCB concentrations measured at Zeppelin according to the 5 different clusters and calculated the median for each cluster and PCB congener. The median for medium to heavier PCBs is highest for cluster 1 and 3, which represent transport regimes over the continent, suggesting that emissions of the respective PCBs dominantly occur over land. However, for the lighter congeners (PCB-18-PCB-47) the highest median concentration corresponds to cluster 2 and the lowest to cluster 3 and 5. The high concentration of the lighter congeners resulting from the transport over the ocean, represented by clusters 2 and to some extent 4, cannot be explained by primary PCB emissions. Also the use of a temperature-dependent primary PCB emission inventory did not resolve this apparent contradiction between high PCB concentrations and a transport regime under which Zeppelin does not receive air from the continents. Our data therefore suggest that in addition to atmospheric transport regimes and primary PCB emissions, also other factors such as secondary emissions from the ocean and/or from soils strongly influence the concentrations of lighter PCBs measured at Zeppelin.

Ubl, S.; Scheringer, M.; Hungerbuehler, K.

2013-12-01

132

Mapping Distant Continental Influences in the Remote Pacific Atmosphere; Simulations of CO Relevant to the Photochemistry of Oxidants  

NASA Technical Reports Server (NTRS)

An animated sequence of maps of simulated carbon monoxide concentrations graphically portrays the extent of residual continental influence upon the tropical Pacific Ocean as studied by NASA aircraft during the PEM-Tropics B intensive sampling campaign. We used the MM5 at a 90 km resolution in a globally wrapped grid to simulate the meteorology of transport, and our GRACES model to follow the basic chemistry. The CO we simulate derives from different sources, and so we distinguish anthropogenic, natural terpenoid oxidation, biomass burning, and pervasive CH4-oxidation influences. "Influence" is always judged with an implicit timescale, and these maps describe influence on the 15-45 day timescale appropriate for CO oxidation. In consequence, the maps are useful in assessing the origins of slowly reacting compounds like acetone, methanol, and the lightest hydrocarbons. At 8 km altitude, The Eastern South Pacific to ca. 130 W (eastern Polynesia) was frequently affected by continental influences but NASA's DC-8's flight path did not happen to take it into these regions very often. Near the surface, continentally influenced air crossed into t he Western South Pacific, in the region northwest of the Southern Pacific Convergence Zone but south of the Intertropical Convergence Zone. This air originated from the NE Pacific, and partly from North America. Comparisons are made to CO and other compounds measured aboard the DC-8 and the P-3 aircraft. We will also use tracers to describe the influence of marine convection in the upper troposphere. As time allows, we will discuss the "age" of ozone within the very cleanest region sampled in portions of the near-equatorial Western South Pacific, using a simple chemical mechanism for ozone levels. These simulations describe the chemistry of an atmosphere with very low ozone.

Chatfield Robert B.; Guo, Z.; Sachse, G.; Singh, H.; Hipskind, R. Stephen (Technical Monitor)

2000-01-01

133

Regional Atmospheric Transport Code for Hanford Emission Tracking, Version 2(RATCHET2)  

SciTech Connect

This manual describes the atmospheric model and computer code for the Atmospheric Transport Module within SAC. The Atmospheric Transport Module, called RATCHET2, calculates the time-integrated air concentration and surface deposition of airborne contaminants to the soil. The RATCHET2 code is an adaptation of the Regional Atmospheric Transport Code for Hanford Emissions Tracking (RATCHET). The original RATCHET code was developed to perform the atmospheric transport for the Hanford Environmental Dose Reconstruction Project. Fundamentally, the two sets of codes are identical; no capabilities have been deleted from the original version of RATCHET. Most modifications are generally limited to revision of the run-specification file to streamline the simulation process for SAC.

Ramsdell, James V.; Rishel, Jeremy P.

2006-07-01

134

The influence of regional feedbacks on circulation sensitivity  

NASA Astrophysics Data System (ADS)

Weakening of the tropical overturning circulation in a warmer world is a robust feature in climate models. Here an idealized representation of ocean heat flux drives a Walker cell in an aquaplanet simulation. A goal of the study is to assess the influence of the Walker circulation on the magnitude and structure of climate feedbacks, as well as to global sensitivity. We compare two CO2 perturbation experiments, one with and one without a Walker circulation, to isolate the differences attributable to tropical circulation and associated zonal asymmetries. For an imposed Walker circulation, the subtropical shortwave cloud feedback is reduced, which manifests as a weaker tropical-subtropical anomalous energy gradient and consequently a weaker slow down of the Hadley circulation, relative to the case without a Walker circulation. By focusing on the coupled feedback circulation system, these results offer insights into understanding changes in atmospheric circulation and hence the hydrological cycle under global warming.

Feldl, N.; Frierson, D. M. W.; Roe, G. H.

2014-03-01

135

Longitudinal variations in the Saturnian atmosphere. I - Equatorial region  

NASA Technical Reports Server (NTRS)

Longitudinal variations in the equatorial regions of Saturn are sought in both Voyager orange and methane-filter and ground-based 6000-6600 A observations. The spectral variations found are inconsistent with reflecting layer height variation; they are alternatively modeled by changes in the single-scattering albedo of the haze, as well as in the specific abundance of haze gas. The 500-km spatial resolution data furnished by Voyager are found to be consistent with a specific abundance of haze gas between 10 and 24 km-am. Ammonia and methane mixing ratios are derived.

Killen, R. M.

1988-01-01

136

Dry and wet atmospheric deposition of nitrogen, phosphorus and silicon in an agricultural region  

Microsoft Academic Search

We measured atmospheric nutrient deposition as wet deposition and dry deposition to dry and wet surfaces. Our analyses offer estimates of atmospheric transport of nitrogen (N), phosphorus (P) and silicon (Si) in an agricultural region. Annual dry and wet deposition (ha?1 year?1) was 0.3 kg of P, 7.7 kg of N, and 6.1 kg of Si; lower than or similar

Kelsy A. Anderson; John A. Downing

2006-01-01

137

Flood regionalization: A hybrid geographic and predictor-variable region-of-influence regression method  

USGS Publications Warehouse

To facilitate estimation of streamflow characteristics at an ungauged site, hydrologists often define a region of influence containing gauged sites hydrologically similar to the estimation site. This region can be defined either in geographic space or in the space of the variables that are used to predict streamflow (predictor variables). These approaches are complementary, and a combination of the two may be superior to either. Here we propose a hybrid region-of-influence (HRoI) regression method that combines the two approaches. The new method was applied with streamflow records from 1,091 gauges in the southeastern United States to estimate the 50-year peak flow (Q50). The HRoI approach yielded lower root-mean-square estimation errors and produced fewer extreme errors than either the predictor-variable or geographic region-of-influence approaches. It is concluded, for Q50 in the study region, that similarity with respect to the basin characteristics considered (area, slope, and annual precipitation) is important, but incomplete, and that the consideration of geographic proximity of stations provides a useful surrogate for characteristics that are not included in the analysis. ?? 2007 ASCE.

Eng, K.; Milly, P.C.D.; Tasker, Gary D.

2007-01-01

138

The impacts of radiation effects of atmospheric aerosol on rice production in the Yangtze Delta Region  

NASA Astrophysics Data System (ADS)

With the rapid pace of industrialization and urbanization, there is a significant increase of the atmospheric aerosol concentrations. The high aerosol concentration has already had negative impacts on ecological environment, especially on crop production, becoming a focus of attention by scientific communities. So far, no dedicated experiments on the impacts of aerosols radiation effects to crop's growth has been conducted yet. This paper intends to assess the impacts through the numerical simulations. In the research, a crop model (Crop-DNDC) is coupled with aerosol radiation effects model. The study is targeted to the rice, a primary crop grown in the Yangtze River Delta region, and the simulations focuses on the impacts of the changing atmospheric aerosol concentrations on rice growth and yield in the region with the coupled model. As the first step, analysis on radiation changes over the Yangtze Delta Region is made. Then the atmospheric aerosol radiation effects model is coupled with Crop-DNDC, which is used to simulate the impacts of radiation effects on rice growth in the region due to changes of aerosol concentration which is expressed by atmospheric optical depth (AOD). It is found that under the current average atmospheric aerosol concentration status over the Yangtze Delta Region (AOD = 0.78), PAR for rice growth period may be reduced by 17.6%, compared with that without the atmospheric aerosol (AOD = 0). Similarly the grain yield of rice may decrease by 9.3%. Our finding shows that if the atmospheric aerosol optical depth is doubled, PAR for rice could be reduced by additional 15.7%. Consequently, the rice grain weight could be decreased by additional 8.1%.

Zhai, Wei; Zhao, Yanxia; Wang, Chunyi; Xia, Xiangao; Xu, Xuan

2008-08-01

139

Influence of high-resolution surface databases on the modeling of local atmospheric circulation systems  

NASA Astrophysics Data System (ADS)

Large-eddy simulations are performed using the Advanced Regional Prediction System (ARPS) code at horizontal grid resolutions as fine as 300 m to assess the influence of detailed and updated surface databases on the modeling of local atmospheric circulation systems of urban areas with complex terrain. Applications to air pollution and wind energy are sought. These databases are comprised of 3 arc-sec topographic data from the Shuttle Radar Topography Mission, 10 arc-sec vegetation-type data from the European Space Agency (ESA) GlobCover project, and 30 arc-sec leaf area index and fraction of absorbed photosynthetically active radiation data from the ESA GlobCarbon project. Simulations are carried out for the metropolitan area of Rio de Janeiro using six one-way nested-grid domains that allow the choice of distinct parametric models and vertical resolutions associated to each grid. ARPS is initialized using the Global Forecasting System with 0.5°-resolution data from the National Center of Environmental Prediction, which is also used every 3 h as lateral boundary condition. Topographic shading is turned on and two soil layers are used to compute the soil temperature and moisture budgets in all runs. Results for two simulated runs covering three periods of time are compared to surface and upper-air observational data to explore the dependence of the simulations on initial and boundary conditions, grid resolution, topographic and land-use databases. Our comparisons show overall good agreement between simulated and observational data, mainly for the potential temperature and the wind speed fields, and clearly indicate that the use of high-resolution databases improves significantly our ability to predict the local atmospheric circulation.

Paiva, L. M. S.; Bodstein, G. C. R.; Pimentel, L. C. G.

2014-08-01

140

The influence of air on streamer propagation in atmospheric pressure cold plasma jets  

Microsoft Academic Search

The formation and propagation mechanisms of atmospheric-pressure cold plasma jets and the influence of air molecules including the nitrogen and the oxygen molecules on them are investigated by a one-dimensional fluid model in a needle-to-plane discharge in helium. It is shown that the air molecules have significant influence on the bullet velocity and the plasma jet length. As the air

Fucheng Liu; Dingzong Zhang; Dezhen Wang

141

The local and regional atmospheric oxidants at Athens (Greece).  

PubMed

In the present study, the investigation of the levels of the local and regional oxidants concentration at Athens, Greece, is attempted by analyzing the observations obtained at an urban and a rural station, during 2001-2011 and 2007-2011, respectively. A progressive increase of the daytime and nighttime average of [NO2]/[Ox] versus [NOx] is observed showing a larger proportion of Ox in the form of NO2 when the level of NOx increases. Similar results are observed when studying the variation of mean values of [NO2]/[NOx] versus [NOx]. The results obtained when compared with those that have earlier detected elsewhere, revealed similarities and discrepancies that are discussed in detail. The parameterized curves that are presented for the first time in this paper may be used by the air quality planners to track the trends in other cities also, and to understand what is or was driving them. PMID:24327116

Varotsos, C A; Ondov, J M; Efstathiou, M N; Cracknell, A P

2014-03-01

142

Atmospheric Response of an Active Region to New Small Flux Emergence  

NASA Astrophysics Data System (ADS)

We investigate the atmospheric response to a small emerging flux region (EFR) that occurred in the positive polarity of Active Region 11236 on 23 - 24 June 2011. Data from the Solar Dynamics Observatory's Atmospheric Imaging Assembly (AIA), the Helioseismic and Magnetic Imager (HMI), and Hinode's EUV imaging spectrometer (EIS) are used to determine the atmospheric response to new flux emerging into a pre-existing active region. Brightenings are seen forming in the upper photosphere, chromosphere, and corona over the EFR location whilst flux cancellation is observed in the photosphere. The impact of the flux emergence is far reaching, with new large-scale coronal loops forming up to 43 Mm from the EFR and coronal upflow enhancements of approximately 10 km s-1 on the north side of the EFR. Jets are seen forming in the chromosphere and the corona over the emerging serpentine field. This is the first time that coronal jets have been seen over the serpentine field.

Shelton, D.; Harra, L.; Green, L.

2015-01-01

143

Influence of atmospheric deposition on Okefenokee National Wildlife Refuge  

USGS Publications Warehouse

Designation of Okefenokee National Wildlife Refuge (Georgia) as a Class I Air Quality Area affords mandatory protection of the airshed through permit-review processes for planned developments. Rainfall is the major source of water to the swamp, and potential impacts from developments in the airshed are high. To meet management needs for baseline information, chemical contributions from atmospheric deposition and partitioning of anions and cations in various matrices of the swamp, with emphasis on mercury and lead, were determined during this study. Chemistry of rainfall was measured on an event basis from one site and quarterly on surface water, pore water, floc, and sediment from four locations. A sediment core collected from the Refuge interior was sectioned, aged, and analyzed for mercury. Rainfall was acidic (pH 4.7-4.9), with average total and methyl mercury concentrations of 9 ng/L and 0.1 ng/L, respectively. Surface waters were acidic (pH 3.8-4.1), dilute (specific conductance 35-60 pS), and highly organic (dissolved organic carbon 35-50 mg/L). Total mercury was 1-3.5 ng/L in surface and pore water, and methyl mercury was 0.02-0.20 ng/L. Total mercury in sediments and floc was 100-200 ng/g dry weight, and methyl mercury was 4-16 ng/g. Lead was 0-1.7 pg/L in rainfall, not detectable in surface water, 3.4-5.4 pg/L in pore water, and 3.9-4.9 mg/kg in floc and sediment. Historical patterns of mercury deposition showed an increase in total mercury from pre-1800 concentrations of 250 ng/g to 500 ng/g in 1950, with concentrations declining thereafter to present.

Winger, P.V.; Lasier, P.J.; Jackson, B.P.

1995-01-01

144

Neutral atmospheric influences of the solar proton events in October--November 2003  

E-print Network

in the Northern Hemisphere polar winter with GOMOS/Envisat data. We provide further evidence of a large middle, most likely a result of the NOy enhancements. Longer-term Northern Hemisphere polar total ozoneNeutral atmospheric influences of the solar proton events in October--November 2003 Charles H

Jackman, Charles H.

145

Subsurface and Atmospheric Influences on Solar Activity ASP Conference Series, Vol. 383, c 2008  

E-print Network

Subsurface and Atmospheric Influences on Solar Activity ASP Conference Series, Vol. 383, c 2008 R-Sheeley- Arge (WSA) model. The WSA model is described in detail in a paper by Arge & 1 Space Sciences Laboratory Corporation (SAIC), 10260 Campus Point Drive, San Diego, CA 92121 USA 3 Air Force Research Laboratory, AFRL

California at Berkeley, University of

146

The influence of processing atmosphere on twin-roll melt-spinning of aluminum alloys  

SciTech Connect

Melt-spun samples of Al-2%Fe have been produced in two different processing atmospheres, ambient pressure argon and a high vacuum. High speed video photography and microstructural analysis of the ribbons indicate that the processing pressure influences the interaction of the melt with the copper rolls and thus the thermal history. This results in significant differences in ribbon microstructure.

Sellers, C.H.; Aldrich, K.S.; Cortez, M.M.; Wright, R.N.

1992-01-01

147

The influence of processing atmosphere on twin-roll melt-spinning of aluminum alloys  

SciTech Connect

Melt-spun samples of Al-2%Fe have been produced in two different processing atmospheres, ambient pressure argon and a high vacuum. High speed video photography and microstructural analysis of the ribbons indicate that the processing pressure influences the interaction of the melt with the copper rolls and thus the thermal history. This results in significant differences in ribbon microstructure.

Sellers, C.H.; Aldrich, K.S.; Cortez, M.M.; Wright, R.N.

1992-09-01

148

Fruit Maturity and Storage Temperature Influence Response of Strawberries to Controlled Atmospheres  

Microsoft Academic Search

Chandler' strawberries (Fragaria ×ananassa Duch.) harvested three-quarter colored or fully red were stored in air or a controlled atmosphere (CA) of 5% O2 + 15% CO2 at 4 or 10 °C to evaluate the influence of fruit maturity and storage temperature on the response to CA. Quality evaluations were made after 1 and 2 weeks in air or CA, and

M. C. N. Nunes; A. M. M. B. Morais; J. K. Brecht; S. A. Sargent

2002-01-01

149

Influences of gas flow on atmospheric pressure glow discharge in helium  

Microsoft Academic Search

Atmospheric pressure glow discharge (APGD) was produced in a 5-mm helium gap between two plane-parallel electrodes of 50 mm in diameter, each covered by a 1-mm thick quartz plate. The influence of the helium gas flowing in parallel through the helium gap on APGD was studied. The helium flow rate varies up to 12 liter per minute, corresponding to helium

H. Luo; Z. Liang; B. Lv; X. Wang; Z. Guan; L. Wang

2008-01-01

150

Natural hazards for the Earth's civilization from space, 1. Cosmic ray influence on atmospheric processes  

Microsoft Academic Search

In this paper we give a short description of global natural disasters for the Earth's civilization from space: 1) Galactic and solar cosmic ray (CR) influence on the atmospheric processes; 2) Impacts of great space magnetic storms during big Forbush-effects in CR, 3) Impacts of great radiation hazards from solar CR during flare energetic particle events, 4) Great impacts on

L. I. Dorman

2008-01-01

151

Long-term middle atmospheric influence of very large solar proton events  

E-print Network

Long-term middle atmospheric influence of very large solar proton events Charles H. Jackman,1 ozone change in these years were not statistically significant. Citation: Jackman, C. H., D. R. Marsh, F, NOy, and ozone [e.g., Heath et al., 1977; Thomas et al., 1983; McPeters and Jackman, 1985; Mc

Jackman, Charles H.

152

Atmospheric Environment 42 (2008) 31153129 Influence of sea-salt activated chlorine and surface-mediated  

E-print Network

Atmospheric Environment 42 (2008) 3115­3129 Influence of sea-salt activated chlorine and surface heterogeneous reactions involving nitrogen oxides and chlorine. Eight modeling scenarios that include the nitrogen oxide renoxification and heterogeneous/multiphase chlorine reactions are presented to quantify how

Dabdub, Donald

153

Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma jet  

E-print Network

Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma March 2014) Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises possibilities of plasma sources under investigation, the non-equilibrium atmospheric pressure plasma jet (APPJ

Zexian, Cao

154

Correlations of atmospheric water ice and dust in the Martian Polar regions  

E-print Network

We report on the interannual variability of the atmospheric ice/dust cycle in the Martian polar regions for Mars Years 28-30. We used CRISM emission phase function measurements to derive atmospheric dust optical depths and data from the MARCI instrument to derive atmospheric water ice optical depths. We have used autocorrelation and cross correlation functions in order to quantify the degree to which dust and ice are correlated throughout both polar regions during Mars Years 28-29. We find that in the south polar region, dust has the tendency to "self clear", demonstrated by negative autocorrelation around the central peak. This does not occur in the north polar region. In the south polar region, dust and ice are temporally and spatially anti correlated. In the north polar region, this relationship is reversed, however temporal correlation of northern dust and ice clouds is weak - 6 times weaker than the anticorrelation in the south polar region. Our latitudinal autocorrelation functions allow us to put avera...

Brown, Adrian J; Scargle, Jeffrey D

2015-01-01

155

21st century climate change scenario for the Mediterranean using a coupled atmosphere–ocean regional climate model  

Microsoft Academic Search

The SAMM (Sea Atmosphere Mediterranean Model) has been developed to study the climate evolution of the Mediterranean and European regions for the 21st Century. SAMM is a new concept of AORCM (Atmosphere–Ocean Regional Climate Model), where a global atmosphere model is locally coupled with a regional ocean circulation model. It consists of the global spectral AGCM ARPEGE-Climate model, whose variable

S. Somot; F. Sevault; M. Déqué; M. Crépon

2008-01-01

156

Use of a regional atmospheric model to simulate lake-atmosphere feedbacks associated with Pleistocene Lakes Lahontan and Bonneville  

USGS Publications Warehouse

A regional model of the atmosphere (version 4 of the NCAR mesoscale model, MM4) was used to assess whether lake-effect precipitation was a significant component of the late-Pleistocene hydrologic budgets of Lakes Lahontan and Bonneville. Control simulations for January and July of 1979 were made using MM4, and the Pleistocene highstand surface areas of the lakes were added to the model and the simulations repeated. In the January simulations, 18% of the moisture added to the modeled atmosphere by Lake Lahontan returned to the Lahontan basin as precipitation, while 32% of the water evaporated from Lake Bonneville fell as precipitation over the Bonneville basin. In the July simulations, 7% of the moisture added to the modeled atmosphere by Lake Lahontan returned to the Lahontan basin as precipitation, and 4% of the water evaporated from Lake Bonneville fell as precipitation over the Bonneville basin. An additonal January simulation was made with the lake surface areas set at onehalf their highstand extents (the average surface area 20 to 15 ka BP). Results from this simulation were similar to the simulation with the highstand lakes, indicating lake-effect precipitation could have been a significant component of the hyrologic budgets of the lakes before and during the highstand period. ?? 1992 Springer-Verlag.

Hostetler, S.W.; Giorgi, F.

1992-01-01

157

Influence of positive slopes on ultrafast heating in an atmospheric nanosecond-pulsed plasma synthetic jet  

NASA Astrophysics Data System (ADS)

The influence of positive slopes on the energy coupling and hydrodynamic responses in an atmospheric nanosecond-pulsed plasma synthetic jet (PSJ) was investigated using a validated dry air plasma kinetics model. Based on a 1D simulation of the energy transfer mechanism in ultrafast gas heating, and with reasonable simplification, a 2D model of a PSJ was developed to investigate the discharge characteristics and hydrodynamic responses under different rise times. In the 1D simulation, a shorter voltage rise time results in a higher electric field in less time, reduces the time of ionization front propagation and produces stronger ionization. The energy transfer efficiency of ultrafast heating is approximately 60% but a steeper positive slope could raise local heating power density and make input energy 77% higher at the cost of 2.4% lower energy transfer efficiency under the same voltage amplitude and pulse width. The quench heating power density is always 27–30 times higher than that of ion collision in most discharge regions, while ion collision heating power density is 10–103 times higher in the sheath region. In 2D PSJ simulation, spatial-temporal distribution of electron density, reduced electric field and deposited energy were calculated for the first time. Heating energy increases sharply with voltage rise time decrease in the time scale of 20–50 ns. Jet velocity increases by 100 m s?1 when the rise time is reduced by 20 ns. A shorter voltage rise time also leads to higher orifice pressure and temperature, but their peak values are limited by the structure of the orifice and the discharge cavity.

Zhu, Yifei; Wu, Yun; Jia, Min; Liang, Hua; Li, Jun; Li, Yinghong

2015-02-01

158

Interacting components of the top-of-atmosphere energy balance affect changes in regional surface temperature  

NASA Astrophysics Data System (ADS)

The role of interactions between components of the top-of-atmosphere (TOA) energy balance in determining regional surface temperature changes, such as polar amplification, is examined in diffusive energy balance model (EBM) simulations. These interactions have implications for the interpretation of local feedback analyses when they are applied to regional surface temperature changes. Local feedback analysis succeeds at accounting for the EBM-simulated temperature change given the changes in the radiative forcing, atmospheric energy transport, and radiative feedbacks. However, the inferences about the effect of individual components of the TOA energy balance on regional temperature changes do not account for EBM simulations in which individual components are prescribed or "locked." As changes in one component of the TOA energy balance affect others, unambiguous attribution statements relating changes in regional temperature or its intermodel spread to individual terms in the TOA energy balance cannot be made.

Merlis, Timothy M.

2014-10-01

159

Developing a broad spectrum atmospheric aerosol characterization for remote sensing platforms over desert regions  

NASA Astrophysics Data System (ADS)

Remotely sensed imagery of targets embedded in Earth's atmosphere requires characterization of aerosols between the space-borne sensor and ground to accurately analyze observed target signatures. The impact of aerosol microphysical properties on retrieved atmospheric radiances has been shown to negatively affect the accuracy of remotely sensed data collects. Temporally and regionally specific meteorological conditions require exact site atmospheric characterization, involving extensive and timely observations. We present a novel methodology which fuses White Sands New Mexico regional aerosol micro pulse lidar (MPL) observations with sun photometer direct and diffuse products for broad-wavelength (visible - longwave infrared) input into the radiative transfer model MODTRAN5. Resulting radiances are compared with those retreived from the NASA Aqua MODIS instrument.

Strong, Shadrian B.; Brown, Andrea M.

2014-05-01

160

Toward constraining regional-scale fluxes of CO2 with atmospheric observations over a continent  

E-print Network

Toward constraining regional-scale fluxes of CO2 with atmospheric observations over a continent: 1 over the continent. To provide a global context for these data, we analyzed the GLOBALVIEW marine observations over a continent: 1. Observed spatial variability from airborne platforms, J. Geophys. Res., 108(D

161

Effects of the Andes on Eastern Pacific Climate: A Regional Atmospheric Model Study  

Microsoft Academic Search

A regional atmospheric model is used to study the effects of the narrow and steep Andes on the eastern Pacific climate. In the Southern Hemisphere cold season (i.e., August October 1999), the model reproduces key climatic features, including the intertropical convergence zone (ITCZ) north of the equator and an extensive low-level cloud deck capped by a temperature inversion to the

Haiming Xu; Yuqing Wang; Shang-Ping Xie

2004-01-01

162

Longitudinal variation of the E-region electric fields caused by atmospheric tides  

Microsoft Academic Search

demonstrated that this could be explained by a longitudinal variation in the diurnal amplitude of atmospheric tides in the E-region ionosphere. An increase in the observed separation of the airglow arcs and a coincident strong increase in the peak ion density in the arcs is indicative of an effect that takes place while ion production is still occurring, such as

S. L. England; S. Maus; T. J. Immel; S. B. Mende

2006-01-01

163

A preliminary analysis of the optical properties of atmosphere in the Millard County region (Utah -USA)  

E-print Network

1 A preliminary analysis of the optical properties of atmosphere in the Millard County region (Utah - USA) Brian Fick - University of Utah (fick@casa.physics.utah.edu) John Matthews - University of New Mexico (johnm@lambda.phys.unm.edu) Paul Sommers - University of Utah (sommers@mail.physics.utah

164

A Regional Ocean Atmosphere Model for Eastern Pacific Climate: Toward Reducing Tropical Biases  

Microsoft Academic Search

The tropical Pacific Ocean is a climatically important region, home to El Niño and the Southern Oscil- lation. The simulation of its climate remains a challenge for global coupled ocean-atmosphere models, which suffer large biases especially in reproducing the observed meridional asymmetry across the equator in sea surface temperature (SST) and rainfall. A basin ocean general circulation model is coupled

Shang-Ping Xie; Toru Miyama; Yuqing Wang; Haiming Xu; Simon P. de Szoeke; R. Justin O. Small; Kelvin J. Richards; Takashi Mochizuki; Toshiyuki Awaji

2007-01-01

165

The influence of inter-annually varying albedo on regional climate and drought  

NASA Astrophysics Data System (ADS)

Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a strengthening of the second mechanism. That is, the second mechanism is stronger in a drought year compared to a normal year and this difference is larger than for the first mechanism. When both mechanisms are active, the second mechanism tends to dominate across the model domain, particularly during the 2002 drought period. The introduction of observed inter-annual variations in albedo produces an enhancement of the first mechanism and a weakening of the second mechanism during the onset of the drought.

Meng, X. H.; Evans, J. P.; McCabe, M. F.

2013-05-01

166

The influence of inter-annually varying albedo on regional climate and drought  

NASA Astrophysics Data System (ADS)

Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a strengthening of the second mechanism. That is, the second mechanism is stronger in a drought year compared to a normal year and this difference is larger than for the first mechanism. When both mechanisms are active, the second mechanism tends to dominate across the model domain, particularly during the 2002 drought period. The introduction of observed inter-annual variations in albedo produces an enhancement of the first mechanism and a weakening of the second mechanism during the onset of the drought.

Meng, X. H.; Evans, J. P.; McCabe, M. F.

2014-02-01

167

Transboundary Atmospheric Pollution of Oil-Gas Industry Emissions from North Caspian region of Kazakhstan  

NASA Astrophysics Data System (ADS)

The Atyraus region (Republic of Kazahstan) is occupied with more than 60 oil-gas fields which are actively developing. Moreover, a new world largest field so-called Kashagan has been discovered on the Caspian Sea shelf and its exploitation is planned by the end of 2012. In our study, this region has been selected as a source region of sulphates emissions accounting about 15 tons (2009 estimates). Three locations have been chosen in the region covering adjacent Caspian Sea aquatoria, and emissions were equally distributed among these locations (with an emission rate of 4.72*10-4 kg/sec). From original sulphates emissions between 46-82% are subjected to atmospheric transport away from the sources. Releases were considered to be continuous. The long-term modelling of atmospheric transport, dispersion and deposition of sulphates was done employing the Lagrangian type model called DERMA, run at the NEC SX6 supercomputing facilities. After each day of release the atmospheric transport has been tracked for the next 2 week period. Input meteorological 3D fields were obtained from the ECMWF data archives. The generated output included air concentration (at model levels), time integrated air concentration, dry and wet deposition (at the surface). The results of dispersion modelling had been post-processed and integrated into GIS environment (using ArcGIS). These have been further used to calculate annual averaged and summary concentration and deposition fields for administrative regions, counties and cities of Kazakhstan, as well as territories of the neighboring countries. It has been found that on an annual scale, the dominating atmospheric transport of pollution from the Atyraus region is toward east and north-east, mostly due to prevailing westerlies. Although on a hemispheric scale, the wet deposition dominates over dry (63 vs. 37%), for Kazakhstan the wet deposition contribution is slightly larger (65%). For Turkmenistan, dry deposition is almost twice higher compared with wet (65 vs. 35%) which is due to significantly smaller precipitation in this country. Considering total deposition during transboundary atmospheric transport, it should be noted that 80.3% of transported sulphates will be deposited over territories of Kazakhstan, 13.8% - Russia, about 2% each - Turkmenistan and Uzbekistan, and less than 1% over other countries. Among considered 14 Regions of Kazakhstan and 8 Federal District of Russia, the highest concentrations and depositions were identified in the Atyraus and Magistaus regions of Kazakhstan as well as in the South Federal District of Russia. For Kazakhstan, the lowest values were identified in the Almaty, East-Kazakhstan, Dzhambul and Pavlodar regions. Among most populated cities the city of Atyrau (Kazakhstan), Astrakhan (Russia) and Baku (Azerbaijan) showed the largest concentrations during transboundary atmospheric transport.

Zakarin, E.; Balakay, L.; Mirkarimova, B.; Mahura, A.; Baklanov, A.; Sorensen, J. H.

2012-04-01

168

The influence of atmospheric turbulence on 3D flash lidar range imagery  

NASA Astrophysics Data System (ADS)

Three dimensional flash imaging lidar technology is widely used in the field of military and national economic construction. The preliminary simulation research is an indispensable aspect in the design of the new lidar. In order to establish a simulation model most close to the real scene, the spatial effect of the simulation system during the laser roundtrip transmission process must be considered. This paper describes the physical mechanism of the formation of atmospheric turbulence, the power spectral density function of the distribution of atmospheric refractive index and the phase distortion due to atmospheric disturbances during light propagation in space. Then the phase-screen distribution of atmospheric turbulence is derived using power spectrum retrieval and time-dependent wavefront tilt parameter. In addition, numerical simulation is conducted using statistical methods. A three dimensional target range imaging simulation model containing laser characteristics, target characteristics, receiver characteristics and laser speckle is established. And the phase screen is introduced into the calculation model to simulate the results in turbulent atmosphere. The major contribution of this paper is transforming the influence of beam spreading and drifting caused by laser propagation in turbulent flow to the influence of target range imaging, which better reveals the diffusion and position drift of imaging on detection surface caused by turbulence. Results show that larger values of refractive index structure parameters and lidar target distance produce blurry and drifting imagery.

Zhao, Yan; Han, Shaokun; Zhao, Wen; Wang, Ping; Xia, Wenze

2013-12-01

169

Evaluating Observation Influence on Regional Water Budgets in Reanalyses  

NASA Technical Reports Server (NTRS)

The assimilation of observations in reanalyses incurs the potential for the physical terms of budgets to be balanced by a term relating the fit of the observations relative to a forecast first guess analysis. This may indicate a limitation in the physical processes of the background model, or perhaps inconsistencies in the observing system and its assimilation. In the MERRA reanalysis, an area of long term moisture flux divergence over land has been identified over the Central United States. Here, we evaluate the water vapor budget in this region, taking advantage of two unique features of the MERRA diagnostic output; 1) a closed water budget that includes the analysis increment and 2) a gridded diagnostic output data set of the assimilated observations and their innovations (e.g. forecast departures). In the Central United States, an anomaly occurs where the analysis adds water to the region, while precipitation decreases and moisture flux divergence increases. This is related more to a change in the observing system than to a deficiency in the model physical processes. MERRAs Gridded Innovations and Observations (GIO) data narrow the observations that influence this feature to the ATOVS and Aqua satellites during the 06Z and 18Z analysis cycles. Observing system experiments further narrow the instruments that affect the anomalous feature to AMSUA (mainly window channels) and AIRS. This effort also shows the complexities of the observing system, and the reactions of the regional water budgets in reanalyses to the assimilated observations.

Bosilovich, Michael G.; Chern, Jiun-Dar; Mocko, David; Robertson, Franklin R.; daSilva, Arlindo M.

2014-01-01

170

The influence of several changes in atmospheric states over semi-arid areas on the incidence of mental health disorders  

NASA Astrophysics Data System (ADS)

The incidence of suicide attempts [Deliberate Self Harm (DSH); ICD-10: X60-X84] and psychotic attacks (PsA; ICD-10, F20-F29) in association with atmospheric states, typical for areas close to big deserts, was analyzed. A retrospective study is based on the 4,325 cases of DSH and PsA registered in the Mental Health Center (MHC) of Ben-Gurion University (Be'er-Sheva, Israel) during 2001-2003. Pearson and Spearman test correlations were used; the statistical significance was tested at p < 0.1. The influence of temperature and humidity on suicide attempts ( N SU ) and psychotic attacks ( N PS ) was weakly pronounced ( p > 0.1). Correlation coefficients between N SU and N PS and speed WS of westerly wind reaches 0.3 ( p < 0.05), while their dependence on easterly WS was weaker ( p > 0.09). Variations in easterly wind direction WD influence N SU and N PS values ( p < 0.04), but no corresponding correlation with westerly winds was found ( p > 0.3). Obviously ,in transition areas located between different regions ,the main role of air streams in meteorological-biological impact can scarcely be exaggerated. An unstable balance in the internal state of a weather-sensitive person is disturbed when the atmospheric state is changed by specific desert winds, which can provoke significant perturbations in meteorological parameters. Results indicate the importance of wind direction, defining mainly the atmospheric situation in semi-arid areas: changes in direction of the easterly wind influence N SU and N PS , while changes in WS are important for mental health under westerly air streams. Obviously, N SU and N PS are more affected by the disturbance of weather from its normal state, for a given season, to which the local population is accustomed, than by absolute values of meteorological parameters.

Yackerson, Naomy S.; Zilberman, Arkadi; Todder, Doron; Kaplan, Zeev

2011-05-01

171

Extracted atmospheric impairments on earth-sky signal quality in tropical regions at Ku-band  

NASA Astrophysics Data System (ADS)

Atmospheric condition variations were shown to have a major effect on the earth sky signal quality at Ku band. Moreover, such variations increased in the tropical regions as compared to temperate areas due to their different weather parameters. With the increase of recent satellite communication technology applications throughout the tropical countries and lack of information regarding the atmospheric impairments analysis, simulation and mitigation techniques, there is an ever increasing need for extracting a unique and accurate performance of the signal quality effects during highly natural tropical weather impairments. This paper presents a new method developed for proper analysis with distinctive and highly realistic performance evaluation for signal quality during the atmospheric conditions variations in 14 tropical areas from the four continents analyzed based on actual measured parameters. The method implementation includes signal attenuation, carrier to noise ratio, symbol energy to noise ratio, and symbol error rate at different areas and different modulation schemes. Furthermore, for improvement in analysis in terms of covering more remarkable regions in tropics, the paper provides new measurements data with analysis for certain region in tropics used as a test bed and to add measurement data of such area to the world's data base for future researchers. The results show a significant investigation and performance observation in terms of weather impairments in tropical regions in general and each region in that area in particular regarding the signal attenuation and error rates accompanied for several transmission schemes.

Al-Saegh, Ali Mohammed; Sali, Aduwati; Mandeep, J. S.; Ismail, Alyani

2013-11-01

172

Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005  

Microsoft Academic Search

Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16-21 January period. Proton fluxes were greatly increased during these several days and led to the production of HOx (H, OH, HO2) and NOx (N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region,

C. H. Jackman; D. R. Marsh; F. M. Vitt; R. G. Roble; C. E. Randall; P. F. Bernath; B. Funke; M. López-Puertas; S. Versick; G. P. Stiller; A. J. Tylka; E. L. Fleming

2011-01-01

173

Evaluation of Atmospheric Electric Field as Increasing Seismic Activity Indicator on the example of Caucasus Region  

NASA Astrophysics Data System (ADS)

The present paper deals with reliability of a gradient of atmospheric electric field potential as an indicator of seismic activity increase. With this in view, records of atmospheric electric field potential gradients of Caucasus region for 1953-1992 with respect to periods before average and large earthquakes, which took place in the same time interval, were considered. It is worth to pay attention to the fact that the avalanche-like unstable model of fault formation based on theoretical model of self-generated seismo-electromagnetic oscillations of LAI system explains convincingly spectral succession of electromagnetic emission frequency of the periods preceding earthquakes.

Kachakhidze, M. K.; Kereselidze, Z. A.; Kachakhidze, N. K.

2013-01-01

174

Evaluation of Atmospheric Electric Field as Increasing Seismic Activity Indicator on the example of Caucasus Region  

E-print Network

The present paper deals with reliability of a gradient of atmospheric electric field potential as an indicator of seismic activity increase. With this in view, records of atmospheric electric field potential gradients of Caucasus region for 1953-1992 with respect to periods before average and large earthquakes, which took place in the same time interval, were considered. It is worth to pay attention to the fact that the avalanche-like unstable model of fault formation based on theoretical model of self-generated seismo-electromagnetic oscillations of LAI system explains convincingly spectral succession of electromagnetic emission frequency of the periods preceding earthquakes.

Kachakhidze, M K; Kachakhidze, N K

2012-01-01

175

Regional constraints on GPP using atmospheric carbonyl sulfide simulations and airborne observations  

NASA Astrophysics Data System (ADS)

A central barrier preventing the scientific community from developing predictive capabilities for carbon-climate feedbacks is methodological; it is challenging to bridge the gap in spatial scales from the detailed process-level understanding obtained from local field measurements and the large-scale earth system models where the understanding of these processes is implemented. This methodological challenge has resulted in large uncertainties in understanding the two primary processes that underlie net ecosystem carbon fluxes: gross primary production (GPP) and respiration. Here we examine constraints on these GPP estimates using new regional atmospheric transport simulations for atmospheric carbonyl sulfide and observations from the NOAA-ESRL network.

Campbell, J.; Zumkehr, A.; Berry, J. A.; Torn, M. S.; Biraud, S.; Montzka, S. A.; Sweeney, C.; Seibt, U. H.; Maseyk, K. S.; Baker, I. T.

2013-12-01

176

The atmospheric influence, size and possible asteroidal nature of the July 2009 Jupiter impactor  

NASA Astrophysics Data System (ADS)

Near-infrared and mid-infrared observations of the site of the 2009 July 19 impact of an unknown object with Jupiter were obtained within days of the event. The observations were used to assess the properties of a particulate debris field, elevated temperatures, and the extent of ammonia gas redistributed from the troposphere into Jupiter's stratosphere. The impact strongly influenced the atmosphere in a central region, as well as having weaker effects in a separate field to its west, similar to the Comet Shoemaker-Levy 9 (SL9) impact sites in 1994. Temperatures were elevated by as much as 6 K at pressures of about 50-70 mbar in Jupiter's lower stratosphere near the center of the impact site, but no changes above the noise level (1 K) were observed in the upper stratosphere at atmospheric pressures less than ˜1 mbar. The impact transported at least ˜2 × 10 15 g of gas from the troposphere to the stratosphere, an amount less than derived for the SL9 C fragment impact. From thermal heating and mass-transport considerations, the diameter of the impactor was roughly in the range of 200-500 m, assuming a mean density of 2.5 g/cm 3. Models with temperature perturbations and ammonia redistribution alone are unable to fit the observed thermal emission; non-gray emission from particulate emission is needed. Mid-infrared spectroscopy of material delivered by the impacting body implies that, in addition to a silicate component, it contains a strong signature that is consistent with silica, distinguishing it from SL9, which contained no evidence for silica. Because no comet has a significant abundance of silica, this result is more consistent with a "rocky" or "asteroidal" origin for the impactor than an "icy" or "cometary" one. This is surprising because the only objects generally considered likely to collide with Jupiter and its satellites are Jupiter-Family Comets, whose populations appear to be orders of magnitude larger than the Jupiter-encountering asteroids. Nonetheless, our conclusion that there is good evidence for at least a major asteroidal component of the impactor composition is also consistent both with constraints on the geometry of the impactor and with results of contemporaneous Hubble Space Telescope observations. If the impact was not simply a statistical fluke, then our conclusion that the impactor contained more rocky material than was the case for the desiccated Comet SL9 implies a larger population of Jupiter-crossing asteroidal bodies than previously estimated, an asteroidal component within the Jupiter-Family Comet population, or compositional differentiation within these bodies.

Orton, G. S.; Fletcher, L. N.; Lisse, C. M.; Chodas, P. W.; Cheng, A.; Yanamandra-Fisher, P. A.; Baines, K. H.; Fisher, B. M.; Wesley, A.; Perez-Hoyos, S.; de Pater, I.; Hammel, H. B.; Edwards, M. L.; Ingersoll, A. P.; Mousis, O.; Marchis, F.; Golisch, W.; Sanchez-Lavega, A.; Simon-Miller, A. A.; Hueso, R.; Momary, T. W.; Greene, Z.; Reshetnikov, N.; Otto, E.; Villar, G.; Lai, S.; Wong, M. H.

2011-01-01

177

Effects of land-conversion in a biosphere-atmosphere model of Northern South America - Part 1: Regional differences in hydrometeorology  

NASA Astrophysics Data System (ADS)

This work investigates how landuse changes over northern South America, driven by human interventions, have affected the regional patterns of hydrology. Comparisons are made to scenarios where no human disturbance of the regional vegetation is assumed. A numerical model of the terrestrial biosphere (Ecosystem Demography Model 2 - ED2) is combined with an atmospheric model (Brazilian Regional Atmospheric Modeling System - BRAMS) to investigate how land conversion in the Amazon and Northern South America have changed the hydrology of the region. Two numerical realizations of the structure and composition of terrestrial vegetation are used as boundary conditions in a simulation of the regional land surface and atmosphere. One realization seeks to capture the present day vegetation condition that includes deforestation and land-conversion, the other is an estimate of the potential structure and composition of the region without human influence. Model output is assessed for consistent and significant pattern differences in hydrometeorology. Results show that South American land conversion has a consistent impact on the regional patterning of precipitation. Land-conversion was not associated with a significant bias in continental mean precipitation, but was associated with a negative bias in mean continental evaporation and a positive bias in continental runoff. A companion paper continues this analysis, with case studies that focus on specific areas that show significant differential hydrologic response.

Knox, R. G.; Longo, M.; Swann, A. L. S.; Zhang, K.; Levine, N. M.; Moorcroft, P. R.; Bras, R. L.

2013-12-01

178

The calculated influence of atmospheric conditions on solar cell ISC under direct and global solar irradiances  

NASA Technical Reports Server (NTRS)

Calculations of the influence of atmospheric conditions on solar cell short-circuit current (Isc) are made using a recently developed computer model for solar spectral irradiance distribution. The results isolate the dependence of Isc on changes in the spectral irradiance distribution without the direct influence of the total irradiance level. The calculated direct normal irradiance and percent diffuse irradiance are given as a reference to indicate the expected irradiance levels. This method can be applied to the calibration of photovoltaic reference cells. Graphic examples are provided for amorphous silicon and monocrystalline silicon solar cells under direct normal and global normal solar irradiances.

Mueller, Robert L.

1987-01-01

179

Influence of high-resolution surface databases on the modeling of local atmospheric circulation systems  

NASA Astrophysics Data System (ADS)

Large-eddy simulations are performed using the Advanced Regional Prediction System (ARPS) code at horizontal grid resolutions as fine as 300 m to assess the influence of detailed and updated surface databases on the modeling of local atmospheric circulation systems of urban areas with complex terrain. Applications to air pollution and wind energy are sought. These databases are comprised of 3 arc-sec topographic data from the Shuttle Radar Topography Mission, 10 arc-sec vegetation type data from the European Space Agency (ESA) GlobCover Project, and 30 arc-sec Leaf Area Index and Fraction of Absorbed Photosynthetically Active Radiation data from the ESA GlobCarbon Project. Simulations are carried out for the Metropolitan Area of Rio de Janeiro using six one-way nested-grid domains that allow the choice of distinct parametric models and vertical resolutions associated to each grid. ARPS is initialized using the Global Forecasting System with 0.5°-resolution data from the National Center of Environmental Prediction, which is also used every 3 h as lateral boundary condition. Topographic shading is turned on and two soil layers with depths of 0.01 and 1.0 m are used to compute the soil temperature and moisture budgets in all runs. Results for two simulated runs covering the period from 6 to 7 September 2007 are compared to surface and upper-air observational data to explore the dependence of the simulations on initial and boundary conditions, topographic and land-use databases and grid resolution. Our comparisons show overall good agreement between simulated and observed data and also indicate that the low resolution of the 30 arc-sec soil database from United States Geological Survey, the soil moisture and skin temperature initial conditions assimilated from the GFS analyses and the synoptic forcing on the lateral boundaries of the finer grids may affect an adequate spatial description of the meteorological variables.

Paiva, L. M. S.; Bodstein, G. C. R.; Pimentel, L. C. G.

2013-12-01

180

Atlantic multidecadal oceanic variability and its influence on the atmosphere in a climate model  

Microsoft Academic Search

The mechanisms controlling the decadal to multidecadal variability of the Atlantic Meridional Overturning Circulation (MOC)\\u000a and its influence on the atmosphere are investigated using a control simulation with the IPSL-CM4 climate model. The multidecadal\\u000a fluctuations of the MOC are mostly driven by deep convection in the subpolar gyre, which occurs south of Iceland in the model.\\u000a The latter is primarily

Rym Msadek; Claude Frankignoul

2009-01-01

181

Photoacoustic measurement of ammonia in the atmosphere: influence of water vapor and carbon dioxide  

Microsoft Academic Search

The photoacoustic determination of the ammonia concentration in atmospheric air by absorption of COâ laser radiation at 9.22 μm is influenced by the presence of HâO and COâ. Kinetic cooling due to the coupling of excited COâ and Nâ levels causes important changes in phase and amplitude of the photoacoustic signal. Theoretical background is presented to deduce the correct NHâ

R. A. Rooth; A. J. L. Verhage; L. W. Wouters

1990-01-01

182

Atmosphere  

NSDL National Science Digital Library

What is this atmosphere that surrounds the Earth? This instructional tutorial, part of an interactive laboratory series for grades 8-12, introduces students to the structure, effects, and components of the atmosphere. Here students investigate the composition of the atmosphere; effects of temperature, pressure, and ozone; the greenhouse effect; and how Earth compares with other planets. Interactive activities present students with opportunities to explore ideas and answer questions about the atmosphere, including its structure, the making of ozone, rocket launching, and measuring the atmosphere. Pop-up boxes provide additional information on topics such as dust, rain, and atmospheric composition. Students complete a final written review of six questions about the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

183

Regional scale variations of atmospheric CO2 and CH4 from satellite observation  

NASA Astrophysics Data System (ADS)

To identify the sources, sinks and changes of atmospheric CO2 and CH4, this study investigates the spatio-temporal changes of atmospheric CO2 and CH4 concentration on the regional scale by the satellite observations. In this paper, choosing the land region of China as the study area, we investigate the spatio-temporal changes of atmospheric CO2 and CH4 concentrations using the data of the CO2 dry air mixing ratio (XCO2), and the CH4 dry air mixing ratio (XCH4), retrieved by the Greenhouse Gases Observing Satellite (GOSAT) from Jan. 2010 to Dec. 2012. The results show that (1) both XCO2 and XCH4 show higher concentrations in southeastern regions than that in the northwestern, and tend to yearly increasing from 2010 to 2013; (2) XCO2 shows obvious seasonal change with higher values in the spring than that in summer. The seasonal peak-to-peak amplitude is 8 ppm and the annual growth is about 2 ppm. XCH4, however, does not show a seasonal change; (3) With regard to different land-use backgrounds, XCO2 shows larger concentrations over the areas of urban agglomeration than that over the grasslands and deserts, and XCH4 shows lower concentrations over deserts than that over the Yangtze River Delta region and Sichuan Basin.

Ru, F.; Lei, L.; Bu, R.; Guan, X.; Qi, J.

2014-03-01

184

LRO Lyman-Alpha Mapping Project (LAMP): Exploration of Permanently Shadowed Regions and the Lunar Atmosphere  

NASA Astrophysics Data System (ADS)

LRO/LAMP is a UV spectrograph designed to address how water is formed on the moon, transported through the lunar atmosphere, and deposited in permanently shadowed regions (PSRs). Its main objectives are to 1) identify exposed water frost in PSRs, 2) characterize landforms and albedos in PSRs, 3) demonstrate the feasibility of using natural starlight and sky-glow illumination for future lunar surface mission applications, and 4) to assay the lunar atmosphere and its variability. The LAMP spectrograph will accomplish the first three objectives by measuring interplanetary HI Ly? sky-glow and FUV starlight reflected from the PSRs. Both of these light sources provide fairly uniform, but faint, illumination (e.g., the reflected Ly? signal is expected to be ~10~R). Thanks to LAMP's sensitivity, however, by the end of the nominal 1-year mission the SNR for a Ly? albedo map will be >100/km2 in the polar regions, allowing the characterization of subtle compositional and structural features. Dayside and nightside lunar surface reflectance measurements of other regions are also planned to measure variations in the illumination sources for improved accuracy. The production and transport of Lunar atmosphere constituents H and Ar will be investigated by observation of their resonantly scattered FUV emissions. The detection and discovery of other constituent emissions is also expected. LAMP albedo maps of PSR landforms and potential surface water ice will be used to identify landing sites for future scientific exploration of these regions and investigation of the intriguing processes that occur within them.

Retherford, K. D.; Stern, S. A.; Black, R. K.; Slater, D. C.; Gladstone, G. R.; Feldman, P. D.; Crider, D. H.; Parker, J. W.; Dirks, G. J.; Versteeg, M. H.; Persson, K. B.; Sykes, H. A.; Davis, M. W.; Stack, J. A.; Case, T. R.; McCullough, L. D.; de Los Santos, A.; Kaufmann, D. E.; Andrews, P. M.

2006-12-01

185

Charge structure of a summer thunderstorm in North China: Simulation using a Regional Atmospheric Model System  

NASA Astrophysics Data System (ADS)

Electrification and simple discharge schemes are coupled into a 3D Regional Atmospheric Model System (RAMS) as microphysical parameterizations, in accordance with electrical experiment results. The dynamics, microphysics, and electrification components are fully integrated into the RAMS model, and the inductive and non-inductive electrification mechanisms are considered in the charging process. The results indicate that the thunderstorm mainly had a normal tripole charge structure. The simulated charge structure and lightning frequency are basically consistent with observations of the lightning radiation source distribution. The non-inductive charging mechanism contributed to the electrification during the whole lifetime of the thunderstorm, while the inductive electrification mechanism played a significant role in the development period and the mature stage when the electric field reached a large value. The charge structure in the convective region and the rearward region are analyzed, showing that the charge density in the convective region was double that in the rearward region.

Liu, Dongxia; Qie, Xiushu; Peng, Liang; Li, Wanli

2014-09-01

186

Human and natural influences on the changing thermal structure of the atmosphere  

PubMed Central

Since the late 1970s, satellite-based instruments have monitored global changes in atmospheric temperature. These measurements reveal multidecadal tropospheric warming and stratospheric cooling, punctuated by short-term volcanic signals of reverse sign. Similar long- and short-term temperature signals occur in model simulations driven by human-caused changes in atmospheric composition and natural variations in volcanic aerosols. Most previous comparisons of modeled and observed atmospheric temperature changes have used results from individual models and individual observational records. In contrast, we rely on a large multimodel archive and multiple observational datasets. We show that a human-caused latitude/altitude pattern of atmospheric temperature change can be identified with high statistical confidence in satellite data. Results are robust to current uncertainties in models and observations. Virtually all previous research in this area has attempted to discriminate an anthropogenic signal from internal variability. Here, we present evidence that a human-caused signal can also be identified relative to the larger “total” natural variability arising from sources internal to the climate system, solar irradiance changes, and volcanic forcing. Consistent signal identification occurs because both internal and total natural variability (as simulated by state-of-the-art models) cannot produce sustained global-scale tropospheric warming and stratospheric cooling. Our results provide clear evidence for a discernible human influence on the thermal structure of the atmosphere. PMID:24043789

Santer, Benjamin D.; Painter, Jeffrey F.; Bonfils, Céline; Mears, Carl A.; Solomon, Susan; Wigley, Tom M. L.; Gleckler, Peter J.; Schmidt, Gavin A.; Doutriaux, Charles; Gillett, Nathan P.; Taylor, Karl E.; Thorne, Peter W.; Wentz, Frank J.

2013-01-01

187

Source regions of some Persistent Organic Pollutants measured in the atmosphere at Birkenes, Norway  

NASA Astrophysics Data System (ADS)

A key feature of POPs (Persistent Organic Pollutants) is their potential for long-range atmospheric transport. In order to better understand and predict atmospheric source-receptor relationships of POPs, we have modified an existing Lagrangian transport model (FLEXPART) to include some of the key processes that control the atmospheric fate of POPs. We also present four years (2004-2007) of new atmospheric measurement data for polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs) obtained at Birkenes, an EMEP (European Monitoring and Evaluation Programme) site in Southern Norway. The model overestimates measured PCB-28 and ?-HCH concentrations by factors of 2 and 8, respectively, which is most likely because the emissions used as input to the model are overestimated. FLEXPART captures the temporal variability in the measurements very well and, depending on season, explains 31-67% (14-62%) of the variance of measured PCB-28 (?-HCH) concentrations. FLEXPART, run in a time-reversed (adjoint) mode, was used to identify the source regions responsible for the POP loading at the Birkenes station. Emissions in Central Europe and Eastern Europe contributed 32% and 24%, respectively, to PCB-28 at Birkenes, while Western Europe was found to be the dominant source (50%) for ?-HCH. Intercontinental transport from North America contributed 13% ?-HCH. While FLEXPART has no treatment of the partitioning of POPs between different surface media, it was found a very useful tool for studying atmospheric source-receptor relationships for POPs and POP-like chemicals that do not sorb strongly to atmospheric particles and whose atmospheric levels are believed to be mainly controlled by primary sources.

Eckhardt, S.; Breivik, K.; Li, Y. F.; Manø, S.; Stohl, A.

2009-05-01

188

Source regions of some persistent organic pollutants measured in the atmosphere at Birkenes, Norway  

NASA Astrophysics Data System (ADS)

A key feature of POPs (Persistent Organic Pollutants) is their potential for long-range atmospheric transport. In order to better understand and predict atmospheric source-receptor relationships of POPs, we have modified an existing Lagrangian transport model (FLEXPART) to include some of the key processes that control the atmospheric fate of POPs. We also present four years (2004-2007) of new atmospheric measurement data for polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs) obtained at Birkenes, an EMEP (European Monitoring and Evaluation Programme) site in southern Norway. The model overestimates measured PCB-28 and ?-HCH concentrations by factors of 2 and 8, respectively, which is most likely because the emissions used as input to the model are overestimated. FLEXPART captures the temporal variability in the measurements very well and, depending on season, explains 31-67% (14-62%) of the variance of measured PCB-28 (?-HCH) concentrations. FLEXPART, run in a time-reversed (adjoint) mode, was used to identify the source regions responsible for the POP loading at the Birkenes station. Emissions in Central Europe and Eastern Europe contributed 32% and 24%, respectively, to PCB-28 at Birkenes, while Western Europe was found to be the dominant source (50%) for ?-HCH. Intercontinental transport from North America contributed 13% ?-HCH. While FLEXPART has no treatment of the partitioning of POPs between different surface media, it was found a very useful tool for studying atmospheric source-receptor relationships for POPs and POP-like chemicals that do not sorb strongly to atmospheric particles and whose atmospheric levels are believed to be mainly controlled by primary sources.

Eckhardt, S.; Breivik, K.; Li, Y. F.; Manø, S.; Stohl, A.

2009-09-01

189

Characteristics of atmospheric density spectra in the mesopause region at Wuhan, China during March 1996  

NASA Astrophysics Data System (ADS)

Sodium layers (75-105 km) were measured by Na lidar on three nights from 1 to 3 of March 1996. The lidar data were used to calculate the Na density profiles and the atmospheric density spectra. The vertical wave number spectra exhibit power-law shapes with average slopes of -2.38 and magnitude at m=2p(3 km) of 8.40 × 105 (m2s-2)/(cyc/m) in the mesopause region.

Ai, Y.; Zhang, X.; Lu, S.; Gong, S.

1998-04-01

190

The Implementation of Regional Atmospheric Model Numerical Algorithms for CBEA-Based Clusters  

Microsoft Academic Search

\\u000a Regional atmospheric models are important tools for short-range weather predictions and future climate change assessment.\\u000a The further enhancement of spatial resolution and development of physical parameterizations in these models need the effective\\u000a implementation of the program code on multiprocessor systems. However, nowadays typical cluster systems tend to grow into\\u000a very huge machines with over petaflop performance, while individual computing node

Dmitry Mikushin; Victor Stepanenko

2009-01-01

191

Mitigating the atmospheric CO2 increase and ocean acidification by adding limestone powder to upwelling regions  

Microsoft Academic Search

The feasibility of enhancing the absorption of CO2 from the atmosphere by adding calcium carbonate (CaCO3) powder to the ocean and of partially reversing the acidification of the ocean and the decrease in calcite supersaturation resulting from the absorption of anthropogenic CO2 is investigated. CaCO3 could be added to the surface layer in regions where the depth of the boundary

L. D. D. Harvey

2008-01-01

192

Evaluation of South American LDAS atmospheric forcing datasets for use in regional land surface modeling over the LBA region  

NASA Astrophysics Data System (ADS)

Significant advances have been made in the past few years by the LBA project on towards understanding how the water, energy and carbon cycles function in the Amazon. However, most of these studies have been limited to results from point measurements from strategically located sites in the tropical forest and other LBA-related areas. As the LBA project progresses into its synthesis phase, there is increased interest in using the acquired knowledge to better understand how Amazonia works as a regional entity. The South American Land Data Assimilation System (SALDAS) initiative, which involves NASA/GSFC, CPTEC/INPE and University of Arizona, provides the capability to integrate results within the robust land surface modeling and data assimilation infrastructure that has already been developed at NASA/GSFC and used for regional studies over the LBA region. This study investigates the feasibility of using the SALDAS atmospheric forcing datasets (a 5 years combination of CPTEC reanalysis and surface observations) for land surface modeling over the Amazonia by comparing these forcing data with seven LBA flux towers observations. The discussion of the results focuses on whether the ranges shown in the evaluation (e.g. standard deviation, bias) are within acceptable ranges for land surface modeling over the region. The results of applying this forcing datasets to force the Noah and SiB3 land surface models over the LBA region are also discussed, with emphasis on the integrated water, energy and carbon budgets.

de Goncalves, L. G.; Shuttleworth, W. J.; Rosolem, R.; Toll, D. L.; Herdies, D.; Baker, I.

2007-12-01

193

Using regional-scale atmospheric ?13C of CO2 as an indicator of ecosystem health and function  

NASA Astrophysics Data System (ADS)

Year to year terrestrial CO2 uptake and release is highly variable and is a result of, among other factors, weather and climate variability. One of the key ecosystem parameters that links surface-atmosphere fluxes of energy, water and carbon is stomatal conductance. By measuring and analyzing atmospheric patterns of CO2 and its 13C content over North America, we can begin to identify regional scale changes in stomatal conductance, because conductance is closely related to plant isotopic discrimination. Furthermore, 13C is a useful tracer of the differential responses of C3 and C4 plants to climate and weather anomalies, because C3 and C4 plants have very different isotopic discrimination. Both aspects of the terrestrial carbon cycle are of great interest to those seeking to understand the potential effects of global climate change on cropland and forest productivity, natural CO2 sinks, continental runoff, and continental water and energy exchange with the atmosphere. Our findings may be particularly important for parameterization of process-based models, in light of recent results suggesting that stomatal conductance models driven by vapor pressure deficit (Leuning Model) better predict atmospheric ?13C than do models driven by relative humidity (Ball-Berry Model). For the first time, spatial and temporal density of ?13C of CO2 atmospheric observations may be high enough to allow for regional inversions of ?13CO2 to optimize prior estimates of plant discrimination (and disequilibrium flux -- an isoflux resulting from the combination of a finite residence time of carbon in terrestrial biosphere pools and a changing atmospheric signature due to human burning of fossil fuels with a plant-derived ?13C signature). We perform a Bayesian synthesis inversion for 1) CO2 fluxes and 2) ?13CO2 isofluxes, over the North American region: 145-25°W longitude and 10-80°N latitude. Inversion resolution, in order to avoid aggregation errors, is 1°x1° and 3-hourly, but optimized fluxes are interpreted at monthly and regional (~106 km2) scales. Influence functions (footprints) are generated with FLEXPART, driven by National Centers for Environmental Prediction Global Forecast System meteorology. Prior information is from CarbonTracker 2011 and SiB, and background CO2 and ?13C values are from NOAA/ESRL marine boundary layer and aircraft data. Quasi-daily atmospheric observations are from NOAA/ESRL Global Monitoring Division tall towers in Park Falls, Wisconsin; Argyle, Maine; Moody, Texas; West Branch, Iowa; and Beech Island, South Carolina. Weekly observations are from Environment Canada tall towers in Estevan Point, British Columbia; Sable Island, Nova Scotia; Fraserdale, Ontario; Churchill, Manitoba; and East Trout Lake, Saskatchewan. We will present optimized, monthly spatial fields of 13C plant discrimination for North America. By comparing these posterior results to the SiB prior, we will begin to evaluate potential shortcomings in SiB with regard to both C3/C4 distribution and conductance.

Alden, C. B.; Miller, J. B.; White, J. W.; Yadav, V.; Michalak, A. M.

2012-12-01

194

Probabilistic indicators of atmospheric transport for regional monitoring and emergency preparedness systems.  

PubMed

In this paper, following a methodology developed within the "Arctic Risk" Project of the Nordic Arctic Research Programme, several probabilistic indicators to evaluate the risk site possible impact on the geographical regions, territories, countries, counties, cities, etc., due to atmospheric transport from the risk site region were suggested. These indicators-maximum possible impact zone, maximum reaching distance, and typical transport time-were constructed by applying statistical methods and using a dataset of isentropic trajectories originated over the selected nuclear risk site (Ignalina nuclear power plant, Lithuania) during 1991-1996. For this site, the areas enclosed by isolines of the maximum possible impact zone and maximum reaching distance indicators are equal to 42 x 10(4) and 703 x 10(4) km(2), respectively. The maximum possible impact zone's boundaries are more extended in the southeast sector from the site and include, in particular, Latvia, Lithuania, Belarus, and several western regions of Russia. The maximum reaching distance's boundaries are twice more extended in the eastern direction from the site (reaching the Caspian Sea) compared with the western direction. The typical transport time to reach the southern territories of Sweden and Finland, northern regions of Ukraine, and northeast of Poland is 1 day. During this time, the atmospheric transport could typically occur over the Baltic States, Belarus, and western border regions of Russia, and central aquatoria of the Baltic Sea. Detailed analysis of temporal patterns for these indicators showed importance of the seasonal variability. PMID:14680889

Mahura, Alexander; Baklanov, Alexander

2004-02-01

195

Medium term modelling of coupled hydrodynamics, turbulence and sediment pathways in a region of freshwater influence.  

NASA Astrophysics Data System (ADS)

Liverpool Bay, in the northwest of the UK, is a shallow, hypertidal region of freshwater influence. In this region, baroclinic processes significantly affect the residual circulation, which in turn influences the long term transport of sediment. A nested modelling system is implemented to simulate the coupled hydro and sediment dynamics in the bay. We use the Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS), which is based on a three-dimensional baroclinic numerical model formulated in spherical polar terrain-following coordinates. The hydrodynamic model solves the three-dimensional, hydrostatic, Boussinesq equations of motion separated into depth-varying and depth-independent parts to allow time splitting between barotropic and baroclinic components. This model is coupled to the General Ocean Turbulence Model (GOTM), to the WAve Model (WAM), and includes state-of-the-art Eulerian and Lagrangian sediment transport models. We implement POLCOMS to Liverpool Bay at a horizontal resolution of approximately 180 m. The bathymetry consists of digitized hydrographic charts combined with LIDAR and multibeam data. Three-dimensional baroclinic effects, river inputs, surface heating and offshore density structure are all considered. Liverpool Bay is subjected to a spring tidal range in excess of 10 m and thus intertidal areas are significant. Wetting and drying algorithms are therefore also implemented. A nesting approach is employed to prescribe offshore boundary conditions for elevations, currents, temperature and salinity. Boundary values are obtained from numerical simulations for the entire Irish and are then used to force the three-dimensional hydrodynamics in the Liverpool Bay domain. Atmospheric forcing consists of hourly wind velocity and atmospheric pressure, and three-hourly cloud cover, humidity and air temperature. We focus here on numerical simulations for a full year, 2008, which is considered to be a typical year for atmospheric, riverine and coastal conditions. We will assess the model's capabilities for currents, water column vertical structure and sediment dynamics via comparisons of numerical results with coastal observations. The observational data were collected at several locations in Liverpool Bay from two moorings, which were part of the National Oceanographic Centre's Coastal Observatory, and from month-long deployments of two bottom-instrumented tripods near the mouth of the Dee Estuary. In turn, the validated numerical results will be interrogated for spatial information on sediment dynamics and pathways in Liverpool Bay, which are difficult to obtain solely from few point measurements.

Amoudry, Laurent; Brown, Jenny; Souza, Alex; Norman, Danielle; Olsen, Karine

2014-05-01

196

Influence of Gas Atmosphere Dew Point on the Galvannealing of CMnSi TRIP Steel  

NASA Astrophysics Data System (ADS)

The Fe-Zn reaction occurring during the galvannealing of a Si-bearing transformation-induced plasticity (TRIP) steel was investigated by field-emission electron probe microanalysis and field-emission transmission electron microscopy. The galvannealing was simulated after hot dipping in a Zn bath containing 0.13 mass pct Al at 733 K (460 °C). The galvannealing temperature was in the range of 813 K to 843 K (540 °C to 570 °C). The kinetics and mechanism of the galvannealing reaction were strongly influenced by the gas atmosphere dew point (DP). After the galvannealing of a panel annealed in a N2+10 pct H2 gas atmosphere with low DPs [213 K and 243 K (-60 °C and -30 °C)], the coating layer consisted of ? (FeZn10) and ? (Zn) phase crystals. The Mn-Si compound oxides formed during intercritical annealing were present mostly at the steel/coating interface after the galvannealing. Galvannealing of a panel annealed in higher DP [263 K and 273 K, and 278 K (-10 °C, 0 °C, and +5 °C)] gas atmospheres resulted in a coating layer consisting of ? and ? (Fe3Zn10) phase crystals, and a thin layer of ? 1 (Fe11Zn40) phase crystals at the steel/coating interface. The Mn-Si oxides were distributed homogeneously throughout the galvannealed (GA) coating layer. When the surface oxide layer thickness on panels annealed in a high DP gas atmosphere was reduced, the Fe content at the GA coating surface increased. Annealing in a higher DP gas atmosphere improved the coating quality of the GA panels because a thinner layer of oxides was formed. A high DP atmosphere can therefore significantly contribute to the suppression of Zn-alloy coating defects on CMnSi TRIP steel processed in hot dip galvanizing lines.

Cho, Lawrence; Kim, Myung Soo; Kim, Young Ha; De Cooman, Bruno C.

2013-11-01

197

Titan's atmospheric and surface properties of the Ontario Lacus region from Cassini/VIMS remote sensing  

NASA Astrophysics Data System (ADS)

The existence of oceans or lakes of liquid hydrocarbons on Titan's surface was predicted more than 20 years ago. These would serve as a source of atmospheric methane and would also contain the end products of the photochemical reactions occurring high in the atmosphere. Although no oceans were ever found, lake-like features poleward of 70°N were first detected by the radar instrument onboard Cassini on July 2006. Before that, Cassini Imaging Science Subsystem (ISS) images of the south pole from June 2005 revealed an intriguing lake-like dark feature named Ontario Lacus. Recently an interesting and important result has been published about the identification of liquid ethane contained within Ontario Lacus (Brown et al. 2008). The authors analysed a near-infrared Visual and Infrared Mapping Spectrometer (VIMS) observation of the Ontario Lacus performed the 2007 December 4, during the T38 flyby. Their result needs nevertheless to be confirmed and improved using a more detailed methodology. Here we report on the analysis of this observation using a radiative transfer model (the libRadtran package) to simulate the atmospheric contribution. LibRadtran is a library of tools developed for radiative transfer calculations in the Earth's atmosphere, but adapted here to Titan's atmospheric conditions. Extinction sources were calculated for atmospheric methane and aerosols as a function of altitude and wavelength. Using the DISORT solver we were able to invert the surface spectrum of the lake interior and of an adjacent, non-lake region, in the near-infrared methane windows. The surface spectra were then compared with spectra of different ices and liquid hydrocarbons, yielding constraints on the possible constituents of Titan's lakes and their adjacent areas. Reference: Brown, R. et al. 2008. The identification of liquid ethane in Titan's Ontario Lacus, Nature 454, 607-610.

Negrão, A.; Adriani, A.; Moriconi, M.; Coradini, A.; D'Aversa, E.; Filacchione, G.; Lunine, J.

2009-04-01

198

The Atmospheric Bridge: The Influence of ENSO Teleconnections on Air-Sea Interaction over the Global Oceans  

Microsoft Academic Search

During El Niño-Southern Oscillation (ENSO) events, the atmospheric response to sea surface temperature (SST) anomalies in the equatorial Pacific influences ocean conditions over the remainder of the globe. This connection between ocean basins via the `atmospheric bridge' is reviewed through an examination of previous work augmented by analyses of 50 years of data from the National Centers for Environmental Prediction-National

Michael A. Alexander; Ileana Bladé; Matthew Newman; John R. Lanzante; Ngar-Cheung Lau; James D. Scott

2002-01-01

199

Atmospheric pollutants and their influence on acidification of rain water at an industrial location on the West Coast OF India  

NASA Astrophysics Data System (ADS)

The chemical analysis of rain water samples at 11 locations along with measurements of atmospheric aerosols and their size distributions were made to study the influence of pollutants on acidification of rain water during the monsoon season of 1990 at Chembur-Trombay area, a highly industrialized belt in Bombay region located on the west coast of India. The concentrations of acid precursor gases, namely, SO 2 and NO, emanating from industries were low and their influence on acidification was limited to a few kilometer radius of their sources. Whereas, the deposition of ionic components (Na +, K +, Ca 2+, Mg 2+ and CI -) whose sources are natural (sea and soil) were uniformly distributed throughout the region as compared to those released from man-made sources. The high concentration of alkaline components, especially Ca 2+ from natural sources and NH 3 released from a fertilizer plant, were responsible for neutralising H + ion concentration generated from the acidic components (SO 42- and N0 3-). The variation from acidic (1970s) to alkaline (1990s) nature of rainwater in the area maybe due to the change in the use of fuel from coal to natural gas, which contains less sulphur and also, the pollution control measures taken by the industries.

Khemani, L. T.; Momin, G. A.; Rao, P. S. P.; Pillai, A. G.; Safai, P. D.; Mohan, K.; Rao, M. G.

200

Influence of Haze on Molecular Lines Formed in the Atmosphere of Titan  

NASA Astrophysics Data System (ADS)

Radiative transfer calculations for the ro-vibrational lines of CH4, C2H2, C2H6, and HCN in atmosphere of Titan have been carried out without consideration of haze opacities (e.g., Yelle and Griffith, 2003), or only for very high (z > 500 km) atmospheric layers where haze influence is assumed to be negligible (e.g., Adriani et al. 2011; and García-Comas et al. 2011). Haze particles are found to exist in the high-altitude atmosphere of Titan, where the absorption lines of these molecules are modified by the haze opacities (Bellucci et al. 2009; Kim et al. 2011). We will present a discussion on the influence of the haze opacities on these molecular lines based on a preliminary result from updated radiative transfer calculations. References Adriani, A. et al. 2011. Icarus 214, 584-595. Bellucci, A. et al. 2009. Icarus 201, 198-216. García-Comas, M. et al. 2011. Icarus 214, 571-583. Kim, et al. 2011. 2011. Planetary and Space Science 59, 699-704. Yelle, R.V., Griffith, C.A., 2003. Icarus 166, 107-115.

Kim, Sang J.

2012-10-01

201

The influence of volcanic eruptions on the climate of the Asian monsoon region during the Common Era  

NASA Astrophysics Data System (ADS)

Most state-of-the-art general circulation models (GCMs) predict that large volcanic eruptions should result in anomalous dry conditions throughout much of monsoon Asia. Here, we use long and well-validated proxy reconstructions of Asian droughts and pluvials to detect the influence of volcanic radiative forcing on the hydroclimate of the region since the late Medieval period. Superposed epoch analysis reveals significantly wetter conditions over mainland southeast Asia in the year of an eruption, with drier conditions in Pakistan, China, and Tibet. The forced GCM simulations examined here predict the opposite response. Our proxy and model comparison suggests that GCMs may not yet capture all of the important ocean-atmosphere dynamics responsible for the influence of explosive volcanism on the Asia monsoon region.

Anchukaitis, K. J.; Buckley, B.; Cook, E.; Cook, B. I.; D'Arrigo, R.; Ammann, C. M.

2010-12-01

202

Influence of equilibrium flows and the atmospheric magnetic field on solar oscillation modes  

NASA Astrophysics Data System (ADS)

The competing effects of an atmospheric magnetic field and an equilibrium flow in the internal regions of the Sun are studied on the helioseismic f- and p-modes. The Sun is modeled as a multi-layered plasma, where the upper parts, representing the chromosphere and corona, are embedded in a unidirectional though inhomogeneous magnetic field, meanwhile the lower part, representing the sub-photospheric polytropic region, is in a steady equilibrium state. The steady state sub-surface region can be considered as a first approximation of dynamic motions (e.g., convective motion, differential rotation, sub-surface flows, meridional flows, etc.). The obtained frequency shifts of the different eigenmodes are associated with flow and magnetic effects. We also found damping of the eigenfrequencies which apparently can be associated with the universal mechanism of resonant absorption. Resonant absorption (already known as a viable heating mechanism in the solar corona) is present due to inhomogeneities in the atmosphere which give rise to Alfvén and slow continua. Damping of helioseismic modes occurs when the modes are coupled into these continua. When both atmospheric magnetic field and sub-surface flows are present, a complex picture of competition of these two effects is found. The theoretically predicted frequency shifts in a steady state are in excellent agreement with the observed values. For related works see also the papers by Erdélyi & Taroyan and Varga & Erdélyi in the present Volume.

Pintér, B.; Erdélyi, R.; New, R.; Goossens, M.

2001-01-01

203

Influence of a high aerosol concentration on the thermal structure of the atmospheric boundary layer  

NASA Astrophysics Data System (ADS)

The influence of increased concentrations of submicron aerosol produced by forest fires on thermal characteristics of the atmospheric boundary layer (ABL) in Moscow and its remote vicinity (the town of Zvenigorod) are analyzed on the basis of regular remote measurements of the ABL temperature profile with the use of MTP-5 profilers. In the air basin of a large city, additional aerosol and accompanying pollutants in early morning hours (at small heights of the Sun) most frequently did not cause substantial changes in the ABL thermal structure. In the locality remote from the megalopolis (Zvenigorod), the atmospheric pollution by aerosol led to noticeable changes in the ABL thermal characteristics. Especially strong changes were observed in the daytime, during the maximum supply of solar radiation. In morning hours, the heating rate of the lower 100-m layer of the polluted air exceeded the heating rate of a relatively pure air by more than one degree. In higher layers, the differences between the rates of temperature changes in a relatively clean atmosphere and in an atmosphere polluted by aerosol (in the suburb) were insignificant.

Khaikin, M. N.; Kuznetsova, I. N.; Kadygrov, E. N.

2006-12-01

204

THE INFLUENCE OF ATMOSPHERIC SCATTERING AND ABSORPTION ON OHMIC DISSIPATION IN HOT JUPITERS  

SciTech Connect

Using semi-analytical, one-dimensional models, we elucidate the influence of scattering and absorption on the degree of Ohmic dissipation in hot Jovian atmospheres. With the assumption of Saha equilibrium, the variation in temperature is the main driver of the variations in the electrical conductivity, induced current, and Ohmic power dissipated. Atmospheres possessing temperature inversions tend to dissipate most of the Ohmic power superficially, at high altitudes, whereas those without temperature inversions are capable of greater dissipation deeper down. Scattering in the optical range of wavelengths tends to cool the lower atmosphere, thus reducing the degree of dissipation at depth. Purely absorbing cloud decks (in the infrared), of a finite extent in height, allow for localized reductions in dissipation and may reverse a temperature inversion if they are dense and thick enough, thus greatly enhancing the dissipation at depth. If Ohmic dissipation is the mechanism for inflating hot Jupiters, then variations in the atmospheric opacity (which may be interpreted as arising from variations in metallicity and cloud/haze properties) and magnetic field strength naturally produce a scatter in the measured radii at a given strength of irradiation. Future work will determine if these effects are dominant over evolutionary effects, which also contribute a scatter to the measured radii.

Heng, Kevin [ETH Zuerich, Institute for Astronomy, Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland)

2012-03-20

205

Atmospheric influence on a laser beam observed on the OICETS - ARTEMIS communication demonstration link  

NASA Astrophysics Data System (ADS)

In 2006 bi-directional optical inter-satellite communication experiments were conducted between the Japan Aerospace Exploration Agency (JAXA) Optical Inter-orbit Communications Engineering Test Satellite (OICETS) and the European Space Agency (ESA) multi-purpose telecommunications and technology demonstration satellite (Advanced Relay and Technology MISsion) ARTEMIS. On 5 April 2006, an experiment was successfully carried out by maintaining the inter-satellite link during OICETS's setting behind the Earth limb until the signal was lost. This setup resembles an occultation observation where the influence of Earth's atmosphere is evident in the power fluctuations recorded at ARTEMIS's (and OICETS's) receiver. These fluctuations do not exist or are at a low level at a link path above the atmosphere and steadily increase as OICETS sets behind the horizon until the tracking of the signal is lost. This specific experiment was performed only once since atmospheric science was not the goal of this demonstration. Nevertheless, this kind of data, if available more frequently in future, can help to study atmospheric turbulence and validate models. The data present here were recorded at ARTEMIS.

Löscher, A.

2010-09-01

206

Atmospheric influence on a laser beam observed on the OICETS - ARTEMIS communication demonstration link  

NASA Astrophysics Data System (ADS)

In 2006 bi-directional optical inter-satellite communication experiments have been conducted between the Japan Aerospace Exploration Agency (JAXA) Optical Inter-orbit Communications Engineering Test Satellite (OICETS) and the European Space Agency (ESA) multi purpose telecommunications and technology demonstration satellite (Advanced Relay and Technology MISsion) ARTEMIS. On 5 April 2006 an experiment was successfully carried out maintaining the inter-satellite link during OICETS's setting behind the Earth limb until the signal was lost. This setup resembles an occultation observation where the influence of Earth's atmosphere is evident in the power fluctuations recorded at ARTEMIS's (and OICETS's) receiver. These fluctuations are not existing or at a low level at a link path above the atmosphere and steadily increase as OICETS sets behind the horizon until the tracking of the signal is lost. This specific experiment was performed only once since atmospheric science was not the goal of this demonstration. Nevertheless this kind of data, if available more frequently in future, can help to study atmospheric turbulence and validate respective models. The data presented here had been recorded at ARTEMIS.

Löscher, A.

2010-05-01

207

NO Detection by Pulsed Polarization of Lambda Probes–Influence of the Reference Atmosphere  

PubMed Central

The pulsed polarization measurement technique using conventional thimble type lambda probes is suitable for low ppm NOx detection in exhaust gas applications. To evaluate the underlying sensor mechanism, the unknown influence of the reference atmosphere on the NO sensing behavior is investigated in this study. Besides answering questions with respect to the underlying principle, this investigation can resolve the main question of whether a simplified sensor element without reference may be also suitable for NO sensing using the pulsed polarization measurement technique. With an adequate sensor setup, the reference atmosphere of the thimble type lambda probe is changed completely after a certain diffusion time. Thus, the sensor response regarding NO is compared with and without different gas atmospheres on both electrodes. It is shown that there is still a very good NO sensitivity even without reference air, although the NO response is reduced due to non-existing overlying mixed potential type voltage, which is otherwise caused by different atmospheres on both electrodes. Considering these results, we see an opportunity to simplify the standard NOx sensor design by omitting the reference electrode.

Fischer, Sabine; Schönauer-Kamin, Daniela; Pohle, Roland; Fleischer, Maximilian; Moos, Ralf

2013-01-01

208

Influence of atmospheric turbulence on the energy focusability of Gaussian beams with spherical aberration  

NASA Astrophysics Data System (ADS)

By using the four-dimensional (4D) computer code of the time-dependent propagation of laser beams through atmospheric turbulence, the influence of atmospheric turbulence on the energy focusability of Gaussian beams with spherical aberration is studied in detail, where the mean-squared beam width, the power in the bucket (PIB), the ? parameter and the energy Strehl ratio are taken as the characteristic parameters. It is shown that turbulence results in beam spreading, and the effect of spherical aberration on the beam spreading decreases due to turbulence. Gaussian beams with negative spherical aberration are more affected by turbulence than those with positive spherical aberration. For the negative spherical aberration case, the focus position moves to the source plane due to turbulence. It is mentioned that the influence of turbulence on the energy focusability defined by a certain energy (i.e. PIB = 63%) is very heavy when the negative spherical aberration is very heavy. On the other hand, the influence of turbulence on the energy focusability defined by the energy within a given bucket radius (i.e. mean-squared beam width) is heaviest when a certain negative spherical aberration coefficient is adopted.

Deng, Jinping; Ji, Xiaoling

2014-05-01

209

Oblique radiation lateral open boundary conditions for a regional climate atmospheric model  

NASA Astrophysics Data System (ADS)

The prescription of lateral boundary conditions in regional atmospheric models represent a very important issue for limited area models. The ill-posed nature of the open boundary conditions makes it necessary to devise schemes in order to filter spurious wave reflections at boundaries, being desirable to have one boundary condition per variable. On the other side, due to the essentially hyperbolic nature of the equations solved in state of the art atmospheric models, external data is required only for inward boundary fluxes. These circumstances make radiation lateral boundary conditions a good choice for the filtering of spurious wave reflections. Here we apply the adaptive oblique radiation modification proposed by Mikoyada and Roseti to each of the prognostic variables of the REMO regional atmospheric model and compare it to the more common normal radiation condition used in REMO. In the proposed scheme, special attention is paid to the estimation of the radiation phase speed, essential to detecting the direction of boundary fluxes. One of the differences with the classical scheme is that in case of outward propagation, the adaptive nudging imposed in the boundaries allows to minimize under and over specifications problems, adequately incorporating the external information.

Cabos Narvaez, William; De Frutos Redondo, Jose Antonio; Perez Sanz, Juan Ignacio; Sein, Dmitry

2013-04-01

210

Complex topography influences atmospheric nitrate deposition in a neotropical mountain rainforest  

NASA Astrophysics Data System (ADS)

Future increase of atmospheric nitrogen deposition in tropical regions is expected to have negative impacts on forests ecosystems and related biogeochemical processes. In tropical mountain forests topography causes complex streamflow and rainfall patterns, governing the atmospheric transport of pollutants and the intensity and spatial variability of deposition. The main goal of the current study is to link spatio-temporal patterns of upwind nitrogen emissions and nitrate deposition in the San Francisco Valley (eastern Andes of southern Ecuador) at different altitudinal levels. The work is based on Scanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) retrieved-NO2 concentrations, NOx biomass burning emissions from the Global Fire Emissions Database (GFEDv3), and regional vehicle emissions inventory (SA-INV) for urban emissions in South America. The emission data is used as input for lagrangian atmospheric backward trajectory modeling (FLEXTRA) to model the transport to the study area. The results show that NO concentrations in occult precipitation samples are significantly correlated to long-range atmospheric secondary nitrogen transport at the highest meteorological stations (MSs) only, whereas for NO concentrations in rain samples this correlation is more pronounced at the lower MSs. We conclude that ion concentrations in occult precipitation at the uppermost MSs are mainly linked to distant emission sources via the synoptic circulation impinging the more exposed higher sites. Lower correlations close to the valley bottom are due to a lower occult precipitation frequency and point to a contamination of the samples by local pollution sources not captured by the used emission data sources.

Makowski Giannoni, Sandro; Rollenbeck, Rütger; Fabian, Peter; Bendix, Jörg

2013-11-01

211

The importance of atmospheric ammonia in the Rocky Mountain region of the western U.S  

NASA Astrophysics Data System (ADS)

Although it is not a regulated pollutant, ammonia is an important contributor to several air quality problems. Included among these are the formation of fine particles that contribute to visibility degradation and adverse health effects as well as contributions to excess nitrogen deposition to sensitive ecosystems. Because it is not regulated, gaseous ammonia and fine particle ammonium have traditionally not been routinely measured in many air quality monitoring networks. Measurements of ammonium wet deposition by the National Atmospheric Deposition Program, however, clearly indicate an increasing contribution to reactive nitrogen deposition. Here we report observations of several recent research efforts to characterize atmospheric ammonia and ammonium in the Rocky Mountain region of the western United States. These include measurements made as part of the Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) deposition study (2006-10), the Grand Teton Reactive Nitrogen Deposition Study (GrandTReNDS) (2011), and through pilot-scale operation of an NHx (NHx = gaseous NH3 plus fine particle NH4+) monitoring effort at 9 sites within the Interagency Monitoring of PROtected Visual Environments (IMPROVE) program (2011-12). Measurements during RoMANS clearly reveal the importance of agricultural source emission contributions to both dry and wet reactive nitrogen deposition in Rocky Mountain National Park. The importance of ammonia and ammonium deposition is even greater at Grand Teton National Park, which often sits downwind of extensive agricultural operations in central Idaho and northern Utah. Over a year of measurements in the IMPROVE NHx pilot network reveals strong spatial gradients in reduced nitrogen concentrations across the Rocky Mountain region, with higher concentrations in regions closer to agricultural sources and at locations and times strongly impacted by wildfires. These observations, along with additional observations from other related studies in the region, will be discussed.

Collett, J. L.; Benedict, K. B.; Chen, D.; Day, D.; Prenni, A. J.; Li, Y.; Kreidenweis, S. M.; Schichtel, B. A.; McDade, C.; Malm, W. C.

2013-12-01

212

Influence of Regional Climate Model spatial resolution on wind climates  

NASA Astrophysics Data System (ADS)

Global and regional climate models are being run at increasingly fine horizontal and vertical resolution with the goal of increased skill. However, relatively few studies have quantified the change in modeled wind climates that derives from applying a Regional Climate Model (RCM) at varying resolutions, and the response to varying resolution may be highly non-linear since most models run in climate mode are hydrostatic. Thus, herein we examine the influence of grid-resolution on modelled wind speeds and gusts and derived extremes thereof over southern Scandinavia using output from the Rossby Centre (RCA3) RCM run at four different resolutions from 50 x 50 km to 6 x 6 km, and with two different vertical grid-spacings. Domain averaged fifty-year return period wind speeds and wind gusts derived using the method of moments approach to compute the Gumbel parameters, increase with resolution (Table 1), though the change is strongly mediated by the model grid-cell surface characteristics. Power spectra of the 3-hourly model time-step ‘instantaneous’ wind speeds and daily wind gusts at all four resolutions show clear peaks in the variance associated with bi-annual, annual, seasonal and synoptic frequencies. The variance associated with these peaks is enhanced with increased resolution, though not in a monotonic fashion, and is more marked in wind gusts than wind speeds. Relative to in situ observations, the model generally underestimates the variance, particularly associated with the synoptic time scale, even for the highest resolution simulations. There is some evidence to suggest that the change in the power spectra with horizontal resolution is less marked in the transition from 12.5 km to 6.25 km, than from 50 to 25 km, or 25 km to 12.5 km.Table 1. Domain averaged mean annual wind speed (U), 50-year return period extreme wind speed (U50yr) and wind gust (Gust50yr) (m/s) from the four RCA3 simulations at different resolution based on output from 1987-2008. The domain extends from approximately 51-60°N, 4-16°E, and thus covers northern Germany, Denmark and southern portions of Norway and Sweden.

Pryor, S. C.; Barthelmie, R. J.; Nikulin, G.; Jones, C.

2010-12-01

213

Influence of cloud edges on atmospheric radiative transfer and its consequences for satellite retrievals  

NASA Astrophysics Data System (ADS)

Clouds have a strong influence on satellite measurements in general and the analysis of absorbing trace gases and aerosol optical depth in particular. Effects of 3D features like spatial heterogeneities and structured cloud boundaries increase when the spatial resolution of the instruments approaches the dimensions of cloud features and if the vertical and horizontal dimensions of clouds are similar: at coarser resolution opposing effects average out, at finer resolution 3D effects may be fully resolved. Hence, measurements by future satellite-borne spectrometers, like the Tropospheric Monitoring Experiment (TROPOMI) designed to resolve horizontal features of 7x7 km2, will be strongly influenced by 3D cloud effects. This type of spectrometer is primarily used to measure trace gases, but aerosol properties may be retrieved as well. In this study, the influence of important 3D effects on atmospheric radiative transfer are investigated using Monte Carlo simulations: effects of cloud shadows, illuminated cloud sides and structured cloud boundaries. We discuss the influence on trace gas retrievals, cloud fractions, and aerosol optical thickness. Additionally, the influence of cloud parameters (e.g. cloud top height, cloud optical density) and observation geometry will be studied. Special emphasis is put on visualising the different effects using the box air-mass factor concept.

Sihler, Holger; Beirle, Steffen; Deutschmann, Tim; Hörmann, Christoph; Penning de Vries, Marloes; Wagner, Thomas

2014-05-01

214

An overview of the regional experiments for land-atmosphere exchanges 2012 (REFLEX 2012) campaign  

NASA Astrophysics Data System (ADS)

The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made.

Timmermans, Wim; Van der Tol, Christiaan; Timmermans, Joris; Ucer, Murat; Chen, Xuelong; Alonso, Luis; Moreno, Jose; Carrara, Arnaud; Lopez, Ramon; de la Cruz Tercero, Fernando; Corcoles, Horacio L.; de Miguel, Eduardo; Sanchez, Jose A. G.; Pérez, Irene; Franch, Belen; Munoz, Juan-Carlos J.; Skokovic, Drazen; Sobrino, Jose; Soria, Guillem; MacArthur, Alasdair; Vescovo, Loris; Reusen, Ils; Andreu, Ana; Burkart, Andreas; Cilia, Chiara; Contreras, Sergio; Corbari, Chiara; Calleja, Javier F.; Guzinski, Radoslaw; Hellmann, Christine; Herrmann, Ittai; Kerr, Gregoire; Lazar, Adina-Laura; Leutner, Benjamin; Mendiguren, Gorka; Nasilowska, Sylwia; Nieto, Hector; Pachego-Labrador, Javier; Pulanekar, Survana; Raj, Rahul; Schikling, Anke; Siegmann, Bastian; von Bueren, Stefanie; Su, Zhongbo (Bob)

2014-12-01

215

A simple method for estimating the influence of eroding soil profiles on atmospheric CO2  

E-print Network

), A simple method for estimating the influence of eroding soil profiles on atmospheric CO2, Global Biogeochem. Cycles, 24, GB2001, doi:10.1029/2009GB003560. 1. Introduction [2] Until recently, soil erosion has often been considered to be a net source... [1998] and has been explored in several modeling and measurement studies [Harden et al., 1999; Smith et al., 2001; Liu et al., 2003; Fang et al., 2006; Rosenbloom et al., 2006; Berhe et al., 2007; Jenerette and Lal, 2007; Quine and Van Oost, 2007; Van...

Billings, Sharon A.; Buddemeier, Robert W.; Richter, D.deB.

2010-04-01

216

Lessons Learned from the Bay Region Atmospheric Chemistry Experiment (BRACE) and Implications for Nitrogen Management of Tampa Bay  

EPA Science Inventory

Results from air quality modeling and field measurements made as part of the Bay Region Atmospheric Chemistry Experiment (BRACE) along with related scientific literature were reviewed to provide an improved estimate of atmospheric reactive nitrogen (N) deposition to Tampa Bay, to...

217

Estimating the Influence of Biological Ice Nuclei on Clouds with Regional Scale Simulations  

NASA Astrophysics Data System (ADS)

Cloud properties are largely influenced by the atmospheric formation of ice particles. Some primary biological aerosol particles (PBAP), e.g. certain bacteria, fungal spores or pollen, have been identified as effective ice nuclei (IN). The work presented here quantifies the IN concentrations originating from PBAP in order to estimate their influences on clouds with the regional scale atmospheric model COSMO-ART in a six day case study for Western Europe. The atmospheric particle distribution is calculated for three different PBAP (bacteria, fungal spores and birch pollen). The parameterizations for heterogeneous ice nucleation of PBAP are derived from AIDA cloud chamber experiments with Pseudomonas syringae bacteria and birch pollen (Schaupp, 2013) and from published data on Cladosporium spores (Iannone et al., 2011). A constant fraction of ice-active bacteria and fungal spores relative to the total bacteria and spore concentration had to be assumed. At cloud altitude, average simulated PBAP number concentrations are ~17 L-1 for bacteria and fungal spores and ~0.03 L-1 for birch pollen, including large temporal and spatial variations of more than one order of magnitude. Thus, the average, 'diagnostic' in-cloud PBAP IN concentrations, which only depend on the PBAP concentrations and temperature, without applying dynamics and cloud microphysics, lie at the lower end of the range of typically observed atmospheric IN concentrations . Average PBAP IN concentrations are between 10-6 L-1 and 10-4 L-1. Locally but not very frequently, PBAP IN concentrations can be as high as 0.2 L-1 at -10° C. Two simulations are compared to estimate the cloud impact of PBAP IN, both including mineral dust as an additional background IN with a constant concentration of 100 L-1. One of the simulations includes additional PBAP IN which can alter the cloud properties compared to the reference simulation without PBAP IN. The difference in ice particle and cloud droplet concentration between both simulations is a result of the heterogeneous ice nucleation of PBAP. In the chosen case setup, two effects can be identified which are occurring at different altitudes. Additional PBAP IN directly enhance the ice crystal concentration at lower parts of a mixed-phase cloud. This increase comes with a decrease in liquid droplet concentration in this part of a cloud. Therefore, a second effect takes place, where less ice crystals are formed by dust-driven heterogeneous as well as homogeneous ice nucleation in upper parts of a cloud, probably due to a lack of liquid water reaching these altitudes. Overall, diagnostic PBAP IN concentrations are very low compared to typical IN concentration, but reach maxima at temperatures where typical IN are not very ice-active. PBAP IN can therefore influence clouds to some extent. Iannone, R., Chernoff, D. I., Pringle, A., Martin, S. T., and Bertram, A. K.: The ice nucleation ability of one of the most abundant types of fungal spores found in the atmosphere, Atmos. Chem. Phys., 11, 1191-1201, 10.5194/acp-11-1191-2011, 2011. Schaupp, C.: Untersuchungen zur Rolle von Bakterien und Pollen als Wolkenkondensations- und Eiskeime in troposphärischen Wolken, Ph.D. thesis, Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany, 2013.

Hummel, Matthias; Hoose, Corinna; Schaupp, Caroline; Möhler, Ottmar

2014-05-01

218

Advanced Modeling Techniques to Study Anthropogenic Influences on Atmospheric Chemical Budgets  

NASA Technical Reports Server (NTRS)

This research work is a collaborative effort between research groups at MCNC and the University of North Carolina at Chapel Hill. The overall objective of this research is to improve the level of understanding of the processes that determine the budgets of chemically and radiatively active compounds in the atmosphere through development and application of advanced methods for calculating the chemical change in atmospheric models. The research performed during the second year of this project focused on four major aspects: (1) The continued development and refinement of multiscale modeling techniques to address the issue of the disparate scales of the physico-chemical processes that govern the fate of atmospheric pollutants; (2) Development and application of analysis methods utilizing process and mass balance techniques to increase the interpretive powers of atmospheric models and to aid in complementary analysis of model predictions and observations; (3) Development of meteorological and emission inputs for initial application of the chemistry/transport model over the north Atlantic region; and, (4) The continued development and implementation of a totally new adaptive chemistry representation that changes the details of what is represented as the underlying conditions change.

Mathur, Rohit

1997-01-01

219

Influence of monsoons on atmospheric CO2 spatial variability and ground-based monitoring over India.  

PubMed

This study examines the role of Asian monsoons on transport and spatial variability of atmospheric CO2 over the Indian subcontinent, using transport modeling tools and available surface observations from two atmospheric CO2 monitoring sites Sinhagad (SNG) and Cape Rama (CRI) in the western part of peninsular India. The regional source contributions to these sites arise from the horizontal flow in conduits within the planetary boundary layer. Greater CO2 variability, greater than 15 ppm, is observed during winter, while it is reduced nearly by half during summer. The SNG air sampling site is more susceptible to narrow regional terrestrial fluxes transported from the Indo-Gangetic Plains in January, and to wider upwind marine source regions from the Arabian Sea in July. The Western Ghats mountains appear to play a role in the seasonal variability at SNG by trapping polluted air masses associated with weak monsoonal winds. A Lagrangian back-trajectory analysis further suggests that the horizontal extent of regional sensitivity increases from north to south over the Indian subcontinent in January (Boreal winter). PMID:24880546

Tiwari, Yogesh K; Vellore, Ramesh K; Ravi Kumar, K; van der Schoot, Marcel; Cho, Chun-Ho

2014-08-15

220

The Influence of the Several Very Large Solar Proton Events in Years 2000-2003 on the Neutral Middle Atmosphere  

NASA Technical Reports Server (NTRS)

Solar proton events (SPEs) are known to have caused changes in constituents in the Earth's neutral middle atmosphere. The highly energetic protons produce ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HOx increases lead to short-lived ozone decreases in the mesosphere and upper stratosphere due to the short lifetimes of the HOx constituents. The NOy increases lead to long-lived stratospheric ozone changes because of the long lifetime of the NOy family in this region. The past four years, 2000-2003, have been replete with SPEs and huge fluxes of high energy protons occurred in July and November 2000, September and November 2001, April 2002, and October 2003. Smaller, but still substantial, proton fluxes impacted the Earth during other months from year 2000 to 2003. The Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model was used in computing the influence of the SPEs. The impact of these extremely large SPEs was calculated to be especially large in the upper stratosphere and mesosphere. The results of the GSFC 2D Model will be shown along with comparisons to the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments.

Jackman, Charles H.; Sinnhuber, Miriam; Anderson, John; McPeters, Richard D.; FLeming, Eric L.; Russell, James M.

2004-01-01

221

Large-scale atmospheric influence on the physical and biogeochemical properties of the Benguela upwelling system  

NASA Astrophysics Data System (ADS)

The Namibian upwelling region is one of the four Eastern Boundary Upwelling Ecosystems and among the most productive areas in the World Ocean. Here, upwelling indices have been defined in three ways. First, by performing EOF analyses of Sea Surface Temperature (SST) observations HadlSST1 and high resolution ocean model simulations (MPI-OM (STORM) and MOM4), driven by meteorological reanalysis. Second, water vertical velocity of STORM and MOM4. Third, the area between the 13°C isotherm and the coastline was used to indicate the intensity of the upwelling. Correlations with observed atmospheric variables (NCEP reanalysis) over the whole southern Atlantic show which conditions favour upwelling: higher than normal South Atlantic anticyclone, strong and southerly wind/wind stress and pressure and air temperature contrast between ocean and land. Separating the coastal area off southern Africa at Lüderitz (28°S) depicts the differences between the northern and southern Benguela upwelling region. Northern Benguela is characterised by a negative trend in upwelling over the last 60 year, Southern Benguela by a positive one. Furthermore, Northern Benguela upwelling seems to be influenced strongly by the conditions described above while the wind field correlated with the upwelling south of 28°S do not show stronger southerly winds. Additionally, the southern upwelling index of MOM4 is not reflected properly in the corresponding SST field. A reason for this could be an overlaying signal, possibly the advection of warm air from the Indian or the central Atlantic Ocean. The sea level pressure (SLP) gradient between land and ocean of NCEP reanalysis provide a opposite trend to the one postulated by Bakun (¹). We did not find an indication for a stronger pressure contrast between land and ocean. Correlations with indices of El Niño Southern Oscillation (ENSO), the Antarctic Oscillation (AAO) and an index of the tropical Atlantic SST variability. None of these correlations is strong enough to claim a detection of a main driver of upwelling. However, a significant relationship between the summer upwelling and ENSO can be found. The SST-based index is also significantly correlated with the tropical Atlantic. In contrast, the upwelling indices of the vertical velocities show significant correlations with the AAO. Spectral analysis of the vertical velocity index (STORM) shows especially in summer a clear peak at timescales of 5 years. The longer series of HadlSST1 additionally displays decadal variability. The oxygen minimum zone in the Benguela region has an important impact on the ecosystem and local fisheries. The content of South Atlantic Central Water (SACW) on the shelf drives the intensity and extension of the oxygen minimum zone. Therefore, the water masses with the STORM and MOM4 simulations have been analysed. The STORM simulation does not contain biogeochemistry and the MOM4 simulation is too short. Thus, the analysis of the water masses, their origin and pathways through the South Atlantic will be analysed with a longer MOM simulation and the MPI run of the Climate Model Intercomparison project 5. (¹) Bakun, A. (1990). Global climate change and intensification of coastal ocean upwelling. Science, 247:198-201.

Tim, Nele; Zorita, Eduardo; Hünicke, Birgit

2014-05-01

222

The influence of Indian Ocean atmospheric circulation on Warm Pool hydroclimate during the Holocene epoch  

NASA Astrophysics Data System (ADS)

Existing paleoclimate data suggest a complex evolution of hydroclimate within the Indo-Pacific Warm Pool (IPWP) during the Holocene epoch. Here we introduce a new leaf wax isotope record from Sulawesi, Indonesia and compare proxy water isotope data with ocean-atmosphere general circulation model (OAGCM) simulations to identify mechanisms influencing Holocene IPWP hydroclimate. Modeling simulations suggest that orbital forcing causes heterogenous changes in precipitation across the IPWP on a seasonal basis that may account for the differences in time-evolution of the proxy data at respective sites. Both the proxies and simulations suggest that precipitation variability during the September-November (SON) season is important for hydroclimate in Borneo. The preëminence of the SON season suggests that a seasonally lagged relationship between the Indian monsoon and Indian Ocean Walker circulation influences IPWP hydroclimatic variability during the Holocene.

Tierney, J. E.; Oppo, D. W.; Legrande, A. N.; Huang, Y.; Rosenthal, Y.; Linsley, B. K.

2012-10-01

223

The Influence of Indian Ocean Atmospheric Circulation on Warm Pool Hydroclimate During the Holocene Epoch  

NASA Technical Reports Server (NTRS)

Existing paleoclimate data suggest a complex evolution of hydroclimate within the Indo-Pacific Warm Pool (IPWP) during the Holocene epoch. Here we introduce a new leaf wax isotope record from Sulawesi, Indonesia and compare proxy water isotope data with ocean-atmosphere general circulation model (OAGCM) simulations to identify mechanisms influencing Holocene IPWP hydroclimate. Modeling simulations suggest that orbital forcing causes heterogenous changes in precipitation across the IPWP on a seasonal basis that may account for the differences in time-evolution of the proxy data at respective sites. Both the proxies and simulations suggest that precipitation variability during the September-November (SON) season is important for hydroclimate in Borneo. The preeminence of the SON season suggests that a seasonally lagged relationship between the Indian monsoon and Indian Ocean Walker circulation influences IPWP hydroclimatic variability during the Holocene.

Tierney, J.E.; Oppo, D. W.; LeGrande, A. N.; Huang, Y.; Rosenthal, Y.; Linsley, B. K.

2012-01-01

224

Regional Influences on U.S. Monetary Policy: Some Implications for Europe  

Microsoft Academic Search

This paper looks at the monetary policy decisions of the U.S. Federal Reserve and asks whether those decisions have been influenced solely by national concerns, or whether regional factors have played a role. All of the Federal Reserve's policymakers have some regional identity, i.e., either their positions explicitly carry some regional affiliation or their region of origin is a factor

Ellen E. Meade; D. Nathan Sheets

2002-01-01

225

Coupling of a regional atmospheric model (RegCM3) and a regional oceanic model (FVCOM) over the maritime continent  

NASA Astrophysics Data System (ADS)

Climatological high resolution coupled climate model simulations for the maritime continent have been carried out using the regional climate model (RegCM) version 3 and the finite volume coastal ocean model (FVCOM) specifically designed to resolve regions characterized by complex geometry and bathymetry. The RegCM3 boundary forcing is provided by the EMCWF-ERA40 re-analysis. FVCOM is embedded in the Global MITgcm which provides boundary forcing. The domain of the coupled regional model covers the entire South China Sea with its through-flow, the entire Indonesian archipelago with the Indonesian through-flow (ITF) and includes a large region in the western Pacific and eastern Indian oceans. The coupled model is able to provide stable and realistic climatological simulations for a specific decade of atmospheric-oceanic variables without flux correction. The major focus of this work is on oceanic properties. First, the coupled simulation is assessed against ocean-only simulations carried out under two different sets of air-sea heat fluxes. The first set, provided by the MITgcm, is proved to be grossly deficient as the heat fluxes are evaluated by a two-dimensional, zonally averaged atmosphere and the simulated SST have anomalous cold biases. Hence the MITgcm fluxes are discarded. The second set, the NCEP re-analysis heat fluxes, produces a climatological evolution of the SST with an average cold bias of ~-0.8 °C. The coupling eliminates the cold bias and the coupled SST evolution is in excellent agreement with the analogous evolution in the SODA re-analysis data. The detailed comparison of oceanic circulation properties with the International Nusantara Stratification and Transport observations shows that the coupled simulation produces the best estimate of the total ITF transport through the Makassar strait while the transports of three ocean-only simulations are all underestimated. The annual cycle of the transport is also very well reproduced. The coupling also considerably improves the vertical thermal structure of the Makassar cross section in the upper layer affected by the heat fluxes. On the other hand, the coupling is relatively ineffective in improving the precipitation fields even though the coupled simulation captures reasonably well the precipitation annual cycle at three land stations in different latitudes.

Wei, Jun; Malanotte-Rizzoli, Paola; Eltahir, Elfatih A. B.; Xue, Pengfei; Xu, Danya

2014-09-01

226

Surface pretreatment of plastics with an atmospheric pressure plasma jet - Influence of generator power and kinematics  

SciTech Connect

The industrial use of atmospheric pressure plasmas in the plastics processing industry has increased significantly in recent years. Users of this treatment process have the possibility to influence the target values (e.g. bond strength or surface energy) with the help of kinematic and electrical parameters. Until now, systematic procedures have been used with which the parameters can be adapted to the process or product requirements but only by very time-consuming methods. For this reason, the relationship between influencing values and target values will be examined based on the example of a pretreatment in the bonding process with the help of statistical experimental design. Because of the large number of parameters involved, the analysis is restricted to the kinematic and electrical parameters. In the experimental tests, the following factors are taken as parameters: gap between nozzle and substrate, treatment velocity (kinematic data), voltage and duty cycle (electrical data). The statistical evaluation shows significant relationships between the parameters and surface energy in the case of polypropylene. An increase in the voltage and duty cycle increases the polar proportion of the surface energy, while a larger gap and higher velocity leads to lower energy levels. The bond strength of the overlapping bond is also significantly influenced by the voltage, velocity and gap. The direction of their effects is identical with those of the surface energy. In addition to the kinematic influences of the motion of an atmospheric pressure plasma jet, it is therefore especially important that the parameters for the plasma production are taken into account when designing the pretreatment processes.

Moritzer, E., E-mail: elmar.moritzer@ktp.upb.de; Leister, C., E-mail: elmar.moritzer@ktp.upb.de [Kunststofftechnik Paderborn (KTP), University of Paderborn, Warburger Strasse 100, D-33098 Paderborn (Germany)

2014-05-15

227

Influence of the Laurentian Great Lakes on Regional Climate1 Michael Notaro, Kathleen Holman8  

E-print Network

1 Influence of the Laurentian Great Lakes on Regional Climate1 2 3 4 5 6 7 Michael Notaro, Kathleen #12;2 Abstract47 48 The influence of the Laurentian Great Lakes on climate is assessed by comparing of the diurnal cycle and annual cycle of air temperature. The53 impacts of the Great Lakes on the regional

Wisconsin at Madison, University of

228

Influence of atmospheric pressure plasma treatment on surface properties of PBO fiber  

NASA Astrophysics Data System (ADS)

In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and Cdbnd O, Osbnd Cdbnd O groups were introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials.

Zhang, Ruiyun; Pan, Xianlin; Jiang, Muwen; Peng, Shujing; Qiu, Yiping

2012-11-01

229

A Study on the Influence of the Land Surface Processes on the Southwest Monsoon Simulations using a Regional Climate Model  

NASA Astrophysics Data System (ADS)

Influence of the land surface processes as an important mechanism in the development of the Indian Summer Monsoon is studied by performing simulations with a regional atmospheric model. Seasonal scale simulations are conducted for two contrasting summer monsoons (MJJAS months) in 2008 & 2009 with the Weather Research and Forecasting-Advanced Research regional model at a high resolution of 15 km using the boundary conditions derived from the National Centers for Environmental Prediction (NCEP) reanalysis data and using the NOAH land surface parameterization scheme. Simulations are evaluated by comparison of precipitation with 0.5° India Meteorological Department gridded rainfall data over land, atmospheric circulation fields with 1° resolution NCEP global final analysis, and surface fluxes with 0.75° resolution Era-Interim reanalysis. Results indicated significant variation in the evolution of the surface fluxes, air temperatures and flux convergence in the 2 contrasting years. A lower albedo, higher heating (sensible, latent heat fluxes), higher air temperatures, stronger flow and higher moisture flux convergence are noted over the subcontinent during the monsoon 2008 relative to the monsoon 2009. The simulated surface fluxes are in good comparison with observations. The stronger flow in 2008 is found to be associated with stronger heat flux gradients as well as stronger north-south geopotential/pressure gradients. The simulations revealed notable differences in many features such as zonal and meridional surface sensible heat gradients which, in turn, influenced the low-level pressure gradients, wind flow, and moisture transport. The present study reveals that, even at a regional scale, the physical processes of land-surface energy partitioning do influence the regional behavior of the monsoon system to a certain extent.

Srinivas, C. V.; Bhaskar Rao, D. V.; Hari Prasad, D.; Hari Prasad, K. B. R. R.; Baskaran, R.; Venkatraman, B.

2014-08-01

230

Deuterium excess in atmospheric water vapor of a Mediterranean coastal wetland: regional versus local signatures  

NASA Astrophysics Data System (ADS)

Stable isotopes of the water vapor represent a powerful tool for tracing atmospheric vapor origin and mixing processes. Laser spectrometry recently allowed high time resolution measurements, but despite an increasing number of experimental studies, there is still a need for a better understanding of the main drivers of isotopic signal variability at different time scales. We present results of in situ measurements of ?18O and ?D during 36 consecutive days in summer 2011 in atmospheric vapor of a Mediterranean coastal wetland exposed to high evapotranspiration (Camargue, Rhône River delta, France). A calibration protocol was tested and instrument stability was analysed over the period. The mean composition of atmospheric vapor during the campaign is ?18O = -14.66‰ and ?D = -95.4‰, with ?v data plotting clearly above the local meteoric water line, and an average deuterium excess (dv) of 21.9‰. At daily time step, we show a clear separation of isotopic characteristics with respect to the air mass back trajectories, with the Northern air masses providing depleted compositions (?18O = -15.83‰, ?D = -103.5‰) compared to Mediterranean air masses (?18O = -13.13‰, ?D = -86.5‰). There is also a clear separation between dv corresponding to these different air mass origins, but not in the same direction as was previously evidenced from regional rainfall data, with higher dv found for Northern air masses (23.2‰) than for Mediterranean air masses (18.6‰). Based on twenty-four average hourly data, we propose a depiction of typical daily evolution of water vapor isotopic composition. High diurnal variations in dv is attributed to a dominant control of evapotranspiration, over entrainment of free atmosphere. Daily cycles in dv are more pronounced for Mediterranean than for North Atlantic air mass origin and are discussed in terms of local evapotranspiration versus regional signatures. We calculate the composition of the vapor source that produces the day-time increase in dv for the different air mass origins, and propose an atmospheric water and isotopic mass balance.

Delattre, H.; Vallet-Coulomb, C.; Sonzogni, C.

2015-01-01

231

Tracing industrial ammonium in atmospheric deposition in the Athabasca Oil Sands Region, Alberta, Canada  

NASA Astrophysics Data System (ADS)

The expanding industrial development in the Athabasca oil sands region (AOSR) in northeastern Alberta, Canada, has raised concerns about increasing nitrogen (N) emissions from oil sands operations and their potential effects on the surrounding terrestrial and aquatic ecosystems. Stable isotope techniques may help to trace industrial emissions provided that they are isotopically distinct from background isotope ratios of atmospheric N compounds. Ammonium deposition rates (NH4-N) typically exceed nitrate deposition rates (NO3-N) in the AOSR (Proemse et al., 2013), suggesting that emissions of reduced nitrogen compounds play a significant role for the atmospheric nitrogen budget in the AOSR. We collected atmospheric ammonium in open field bulk deposition and throughfall using ion exchange resins over ~6 months time periods from summer 2007 to summer 2011 located at distances between 3 to 113 km to one of the major oil sands developments in the AOSR. Ammonium deposition rates and ?15N-NH4 values were determined using ion chromatography and the ammonium diffusion method (Sebilo et al., 2004) on resin extracts. Atmospheric ammonium deposition rates in open field bulk collectors and throughfall collectors ranged from 1.0 to 4.7 kg ha-1 yr-1 NH4-N, and from 1.0 to 18.3 kg ha-1 yr-1 NH4-N, respectively. ?15N-NH4 values varied from -6.3 to +14.8‰ with the highest ?15N values typically associated with elevated NH4-N deposition rates. ?15N-NH4 values of up to +20.1‰ were observed for industrially emitted NH4 in particulate matter (PM2.5) emissions (Proemse et al., 2012) suggesting that industrial NH3 and NH4 emissions are associated with elevated ?15N values providing a potential tracer. Applying a two-end-member mixing analysis using a background ?15N-NH4 value of -3.6‰ for summer and -3.2‰ for winter periods revealed that particularly sites within ~30 km radius from the main oil sands developments are significantly affected by industrial contributions to atmospheric NH4 deposition. References: Sebilo et al., 2004: Environmental Chemistry, Vol. 1, 99-103. Proemse et al., 2012: Atmospheric Environment, Vol. 60, 555-563. Proemse et al., 2013: Environmental Pollution, Vol. 182, 80-91.

Mayer, B.; Proemse, B. C.; Fenn, M. E.

2013-12-01

232

Influence of solar forcing, climate variability and atmospheric circulation patterns on summer floods in Switzerland  

NASA Astrophysics Data System (ADS)

The higher frequency of severe flood events in Switzerland in recent decades has given fresh impetus to the study of flood patterns and their possible forcing mechanisms, particularly in mountain environments. This paper presents an index of summer flood damage that considers severe and catastrophic summer floods in Switzerland between 1800 and 2009, and explores the influence of solar and climate forcings on flood frequencies. In addition, links between floods and low-frequency atmospheric circulation patterns are examined. The flood damage index provides evidence that the 1817-1851, 1881-1927, 1977-1990 and 2005-present flood clusters occur mostly in phase with palaeoclimate proxies. The cross-spectral analysis documents that the periodicities detected in the coherency and phase spectra of 11 (Schwabe cycle) and 104 years (Gleissberg cycle) are related to a high frequency of flooding and solar activity minima, whereas the 22 year cyclicity detected (Hale cycle) is associated with solar activity maxima and a decrease in flood frequency. The analysis of atmospheric circulation patterns shows that Switzerland lies close to the border of the summer principal mode: the Summer North Atlantic Oscillation. The Swiss river catchments situated on the centre and southern flank of the Alps are affected by atmospherically unstable areas defined by the positive phase of the Summer North Atlantic Oscillation pattern, while those basins located in the northern slope of the Alps are predominantly associated with the negative phase of the pattern. Furthermore, a change in the low-frequency atmospheric circulation pattern related to the major floods occurred over the period from 1800 to 2009: the Summer North Atlantic Oscillation persists in negative phase during the last cool pulses of the Little Ice Age (1817-1851 and 1881-1927 flood clusters), whereas the positive phases of SNAO prevail during warmer climate of the last four decades (flood clusters from 1977 to present).

Peña, J. C.; Schulte, L.; Badoux, A.; Barriendos, M.; Barrera-Escoda, A.

2014-12-01

233

Predicting wetland contamination from atmospheric deposition measurements of pesticides in the Canadian Prairie Pothole region  

NASA Astrophysics Data System (ADS)

Although it has been suggested that atmospheric deposition alone can result in detectable levels of pesticides in wetlands of the Pairie Pothole Region of Canada, this is the first field study to compare the masses of pesticides entering wetlands by atmospheric deposition with those concentrations of pesticides detected in the water-column of prairie wetlands. Weekly air and bulk deposition samples were collected from May 26th to Sept. 15th, 2008 at the Manitoba Zero Tillage Research Association (MZTRA) Farm, Brandon, Manitoba, with four on-site wetlands (approximate sizes 0.15-0.45 ha) monitored every second week. Twelve pesticides were detected in the air, with MCPA (one of the three pesticides applied on the farm in 2008 in addition to clopyralid and glyphosate), triallate, and ?-HCH being detected every week. Calculations were performed to predict wetland pesticide concentrations based on bulk deposits alone for those pesticides that had detectable concentrations in the bulk deposition samples (in order of the highest total seasonal deposition mass to the lowest): MCPA, glyphosate, 2,4-D, clopyralid, bromoxynil, atrazine, dicamba, metolachlor, and mecoprop. The estimated concentrations were closest to actual concentrations for MCPA (Pearson correlation coefficient's = 0.91 to 0.98; p-values < 0.001) and predictions were also reasonable for a range of other herbicides, but a source other than atmospheric deposition was clearly relevant to detections of clopyralid in the wetland water-column. Although the types and levels of pesticides detected in the wetlands of the current study suggest that regional pesticide applications can contribute to pesticide surface water contamination following atmospheric transport and deposition, the greater frequency and concentrations of clopyralid, MCPA, and glyphosate detections in wetlands confirm that on-farm pesticide applications have a greater impact on on-site water quality. Beneficial management practices that reduce application drift, as well as rainfall or snowmelt runoff, will be important measures in reducing pesticide loading into wetlands situated in agricultural fields of the Prairie Pothole Region of North America.

Messing, Paul G.; Farenhorst, Annemieke; Waite, Don T.; McQueen, D. A. Ross; Sproull, James F.; Humphries, David A.; Thompson, Laura L.

2011-12-01

234

Spatial Variation of Soil Type and Soil Moisture in the Regional Atmospheric Modeling System  

SciTech Connect

Soil characteristics (texture and moisture) are typically assumed to be initially constant when performing simulations with the Regional Atmospheric Modeling System (RAMS). Soil texture is spatially homogeneous and time-independent, while soil moisture is often spatially homogeneous initially, but time-dependent. This report discusses the conversion of a global data set of Food and Agriculture Organization (FAO) soil types to RAMS soil texture and the subsequent modifications required in RAMS to ingest this information. Spatial variations in initial soil moisture obtained from the National Center for Environmental Predictions (NCEP) large-scale models are also introduced. Comparisons involving simulations over the southeastern United States for two different time periods, one during warmer, more humid summer conditions, and one during cooler, dryer winter conditions, reveals differences in surface conditions related to increases or decreases in near-surface atmospheric moisture con tent as a result of different soil properties. Three separate simulation types were considered. The base case assumed spatially homogeneous soil texture and initial soil moisture. The second case assumed variable soil texture and constant initial soil moisture, while the third case allowed for both variable soil texture and initial soil moisture. The simulation domain was further divided into four geographically distinct regions. It is concluded there is a more dramatic impact on thermodynamic variables (surface temperature and dewpoint) than on surface winds, and a more pronounced variability in results during the summer period. While no obvious trends in surface winds or dewpoint temperature were found relative to observations covering all regions and times, improvement in surface temperatures in most regions and time periods was generally seen with the incorporation of variable soil texture and initial soil moisture.

Buckley, R.

2001-06-27

235

Regional frequency analysis conditioned on large-scale atmospheric or oceanic fields  

NASA Astrophysics Data System (ADS)

studies report that hydrologic regimes are modulated by large-scale modes of climate variability such as the El Niño Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO). Climate-informed frequency analysis models have therefore been proposed to condition the distribution of hydrologic variables on climate indices. However, standard climate indices may be poor predictors in some regions. This paper therefore describes a regional frequency analysis framework that conditions the distribution of hydrologic variables directly on atmospheric or oceanic fields, as opposed to predefined climate indices. This framework is based on a two-level probabilistic model describing both climate and hydrologic data. The climate data set (predictor) is typically a time series of atmospheric of oceanic fields defined on a grid over some area, while the hydrologic data set (predictand) is typically a regional data set of station data (e.g., annual average flow at several gauging stations). A Bayesian estimation framework is used, so that a natural quantification of uncertainties affecting hydrologic predictions is available. A case study aimed at predicting the number of autumn flood events in 16 catchments located in Mediterranean France using geopotential heights at 500 hPa over the North-Atlantic region is presented. The temporal variability of hydrologic data is shown to be associated with a particular spatial pattern in the geopotential heights. A cross-validation experiment indicates that the resulting probabilistic climate-informed predictions are skillful: their reliability is acceptable and they are much sharper than predictions based on standard climate indices and baseline predictions that ignore climate information.

Renard, Benjamin; Lall, Upmanu

2014-12-01

236

Atmospheric mercury observations from Antarctica: seasonal variation and source and sink region calculations  

NASA Astrophysics Data System (ADS)

Long term atmospheric mercury measurements in the Southern Hemisphere are scarce and in Antarctica completely absent. Recent studies have shown that the Antarctic continent plays an important role in the global mercury cycle. Therefore, long term measurements of gaseous elemental mercury (GEM) were initiated at the Norwegian Antarctic Research Station, Troll (TRS) in order to improve our understanding of atmospheric transport, transformation and removal processes of GEM. GEM measurements started in February 2007 and are still ongoing, and this paper presents results from the first four years. The mean annual GEM concentration of 0.93 ± 0.19 ng m-3 is in good agreement with other recent southern-hemispheric measurements. Measurements of GEM were combined with the output of the Lagrangian particle dispersion model FLEXPART, for a statistical analysis of GEM source and sink regions. It was found that the ocean is a source of GEM to TRS year round, especially in summer and fall. On time scales of up to 20 days, there is little direct transport of GEM to TRS from Southern Hemisphere continents, but sources there are important for determining the overall GEM load in the Southern Hemisphere and for the mean GEM concentration at TRS. Further, the sea ice and marginal ice zones are GEM sinks in spring as also seen in the Arctic, but the Antarctic oceanic sink seems weaker. Contrary to the Arctic, a strong summer time GEM sink was found, when air originates from the Antarctic plateau, which shows that the summertime removal mechanism of GEM is completely different and is caused by other chemical processes than the springtime atmospheric mercury depletion events. The results were corroborated by an analysis of ozone source and sink regions.

Pfaffhuber, K. A.; Berg, T.; Hirdman, D.; Stohl, A.

2012-04-01

237

Atmospheric mercury observations from Antarctica: seasonal variation and source and sink region calculations  

NASA Astrophysics Data System (ADS)

Long term atmospheric mercury measurements in the Southern Hemisphere are scarce and in Antarctica completely absent. Recent studies have shown that the Antarctic continent plays an important role in the global mercury cycle. Therefore, long term measurements of gaseous elemental mercury (GEM) were initiated at the Norwegian Antarctic Research Station, Troll (TRS) in order to improve our understanding of atmospheric transport, transformations and removal processes of GEM. GEM measurements started in February 2007 and are still ongoing, and this paper presents results from the first four years. The mean annual GEM concentration was 0.93±0.19 ng m-3 and is in good agreement with other recent southern hemispheric measurements. Measurements of GEM were combined with the output of the Lagrangian particle dispersion model FLEXPART, for a statistical analysis of GEM source and sink regions. It was found that the ocean is a source of GEM to TRS year round, especially in summer and fall. None of the Southern Hemisphere continents contribute significantly to the direct transport of GEM to TRS, but they are important for determining the overall GEM load in the Southern Hemisphere and for the mean GEM concentration at TRS. Further, the sea ice and marginal ice zones are GEM sinks in spring as also seen in the Arctic, but the Antarctic oceanic sink seems weaker. Contrary to the Arctic, a strong summer time GEM sink was found, when air originates from the Antarctic Plateau, which shows that the summertime removal mechanism of GEM is completely different and is caused by other chemical processes than the springtime atmospheric mercury depletion events. The results were corroborated by an analysis of ozone source and sink regions.

Aspmo Pfaffhuber, K.; Berg, T.; Hirdman, D.; Stohl, A.

2011-10-01

238

Towards a regional CO2 budget for New Zealand from atmospheric measurements and backward Lagrangian modeling  

NASA Astrophysics Data System (ADS)

Between 1990 and 2011, the reported average annual growth in total greenhouse gas emissions had been 1.0% for New Zealand, with emissions reaching 73 Mt CO2-e in 2011. At the same time the net emissions (total plus LULUCF) grew by 4.2% each year on average and reached 59 Mt CO2-e in 2011, according to the Ministry for the Environment. This implies a shrinking sink for greenhouse gases in areas of land use/ land use change and forests (LULUCF). The uptake of CO2 by forests is the largest contributor to this sink and, therefore, plays a crucial role in New Zealand's carbon budget. Yet, it is among the least well-known components. In this study, we aim to develop a regional atmosphere inversion system to estimate net CO2 uptake by land areas in 2011 and 2012. This will serve as an alternative to the bottom-up estimates outlined above. We use the UK Met Office's Lagrangian dispersion model NAME III to link CO2 measurements at stations directly to atmospheric transport and potential source regions at the surface. By running the model in backward mode, we identify the degree to which potential regional sources of CO2 contribute to observed mid-afternoon mixing ratios, i.e., the footprint of a station. Footprints are computed over 2011-2012 for three stations across New Zealand: Baring Head, Lauder and Rainbow Mountain. NAME III uses hourly meteorological input from the regional forecast model NZLAM-12 over a domain covering New Zealand and the Tasman Sea at a horizontal resolution of 12 km. The footprints are then used in a regional inversion to find the optimal distribution of CO2 sources and sinks, i.e., the one leading to the best match with the measurements at all stations. We present results from the footprint analysis and show that the three stations are sensitive to distinct source regions that do not overlap and, together, cover large parts of New Zealand. Hence, the data from the stations carry complementary information on CO2 sinks in sources throughout the country, which can be exploited by the inversion. We also present preliminary estimates for the regional CO2 budget from the inversion.

Steinkamp, K.; Mikaloff-Fletcher, S.; Brailsford, G. W.; Moore, S.

2013-12-01

239

Bog Plant Tissue Chemistry as Indicators of Regionally Elevated Atmospheric N and S Deposition in the Alberta Oil Sands Region  

NASA Astrophysics Data System (ADS)

Nitrogen oxide and sulfur oxide emission from ongoing development of oil sands in northern Alberta results in regionally elevated atmospheric deposition of N and S in an area where background deposition of both N and S is exceptionally low (less than 1 kg/ha/yr). Because bogs, which represent major landforms in the Alberta oil sands region, are believed to be N-limited and potentially sensitive to S inputs, we have been investigating the effects of elevated N deposition on C, N, and S cycling in bogs, as well as the potential of bogs to serve as monitors of N and S deposition. Toward this latter end, we have measured seasonal variation (5 sampling dates between June and October 2009) concentrations of N and S, as well as ?15N value, in leaf tissues (Picea mariana (ectomycorrhizal); Ledum groenlandicum, Oxycoccos microcarpon, Vaccinium vitis-idaea (ericoid mycorrhizal); Rubus chamaemorus, and Smilacina trifolia (nonmycorrhizal), Sphagnum (S. fuscum, S. capillifolium, S. magellanicum, S. angustifolium) moss capitula (top 1-cm of plant) and lichens (Cladina mitis and Evernia mesomorpha) at 5 bogs at distances ranging from 14 to 300 km from the heart of the oil sands mining area. Averaged across all sites and sampling dates, N concentrations in ectomycorrhizal, ericoid mycorrhizal, nonmycorrhizal, Sphagnum, and lichens was 8.6 + 0.2, 11.9 + 0.2, 26.3 + 0.6, 10.2 + 0.1, 7.2 + 0.2 mg/g, respectively; ?15N values were -10.3 + 0.1, -6.0 + 0.1, 1.7 + 0.2, -5.3 + 0.1, -4.7 + 0.1 mg/g, respectively, and S concentrations were 1.07 + 0.2, 1.31 + 0.2, 1.94 + 0.6, 1.46 + 0.2, 1.11 + 0.3 mg/g, respectively. Plant functional groups and individual species behaved differently with respect to both seasonal variation and site differences, often with significant interactions when analyzed using two-way analyses of variance. Some species exhibited seasonal variation in some aspects of plant tissue chemistry, while others did not; when a species did exhibit seasonal variation, the variation was rather consistent between sites. More importantly, however, canonical discriminant analysis (with potential variables of C, N, or S concentrations, C:N, C:S, or N:S ratios, and ?15N values) indicated that the five sites can be differentiated based on plant tissue chemistry, most clearly separating the site closest and the site farthest from the oil sands mining area. The first canonical axis explained between 66 and 91 percent of the overall variation, but the variables that were significantly correlated with the first canonical axis differed between species. We conclude that plant tissue chemistry exhibited a significant variation between plant functional groups, between species, between sites, and seasonally. Some of this variation appears to be related to distance from the heart of oil sands mining activity in northern Alberta, possibly reflecting regionally elevated atmospheric deposition of N and S. Bog plants, through analysis of tissue chemistry, have the potential to serve as biomonitors of the anticipated spread of elevated atmospheric N and S deposition as oil sands development continues to grow in northern Alberta.

Wieder, R.; Vile, M. A.; Scott, K. D.; Vitt, D. H.; Quinn, J.

2011-12-01

240

Influences of impedance matching network on pulse-modulated radio frequency atmospheric pressure glow discharges  

SciTech Connect

Pulse-modulated RF atmospheric pressure glow discharges (APDGs) were investigated in recent years to reduce the thermal accumulation and extend the operation region of the stable alpha glow mode. Different pulse-modulated voltage and current waveforms were acquired in previous experiments, but no attention was paid to the interpretation. We investigated this issue and associated phenomenon via positive and negative feedback effects derived from varying the series capacitor in the inversely L-shaped matching network used in our pulse-modulated RF APGD source. The evolutions of pulse-modulated RF waveforms were found to be associated with the feedback region and the pulsed plasma absorbed RF power. In the positive feedback region, pulse-modulated RF APGDs are relatively stable. In the negative feedback region, wide spikes as well as undershoots occur in RF voltage and current waveforms and the plasma absorbed RF power. In case of a high RF power discharge with a low modulation frequency, the pulse-modulated RF APGD is extinguished and re-ignited due to the enhanced undershoot during the initial pulse phase. The pulse-modulated RF APGD can transit from positive to negative feedback region in a range of series capacitance. Experimental results are discussed by the aid of equivalent circuit, negative and positive feedback effects.

Huo, W. G. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029 (China); Xu, K.; Sun, B.; Ding, Z. F. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2012-08-15

241

Atmosphere aerosol transfer and sources localisation in the East European region by AERONET data  

NASA Astrophysics Data System (ADS)

The typical transfer paths of atmospheric aerosol particles registered at five AERONET network stations equipped by sunphotometers in Belsk, Kyiv, Kishinev, Minsk, Sevastopol, were investigated by the cluster analysis and back trajectory methods. The transfer of fine- and coarse mode particles is considered in warm and cold times of year. The territories, where the air masses bringing to the monitoring stations the aerosol with the total volume column content exceeded mean values in 1.5 times, were revealed. For the same stations the cases of enhanced fine and coarse aerosol faction concentrations and correspondent source regions have been revealed by the method of trajectory statistics. The enhanced aerosol concentration areas were identified with potential sources. In the average for all stations the air masses with the large concentration values of coarse mode aerosol particles were brought from the Donetsk, Rostov, and Kharkiv regions. The fine mode aerosol fraction comes mostly from Tambov, Voronezh and Kharkov areas. The localized aerosol source regions are partially correspond to the European Monitoring and Evaluation Programme (EMEP) data for East Europe. The cause of difference between calculated regions of enhanced aerosol content releases and sources of particle emission by EMEP data are discussed. This publication is based on work supported by US CRDF Award No. UKG2-2969-KV-09, by the projects F41/106-2012 Derzhinformnauky of Ukraine and the project F11?-88 of Belarusian Republican Foundation for Fundamental Research.

Milinevsky, Gennadi; Kabashnikov, Vitaly; Aculinin, Aleksandr; Danylevsky, Vassyl; Kalinskaya, Dariya; Korchemkina, Elena; Miatselskaya, Nataliya; Bovchaliuk, Andrii; Pietruczuk, Alexander; Sobolewsky, Piotr; Chaikovsky, Anatoly

2013-04-01

242

Influence of the local ionization sources on ionospheric densities in Titan's upper atmosphere  

NASA Astrophysics Data System (ADS)

Titan holds the most complex ionosphere in the Solar System, as revealed through flybys of the moon by Cassini since Fall 2004. The current understanding is that on the sunlit side, the ionosphere is produced mainly by EUV solar radiation, while on the darkside the sources of ions include ionization by precipitating electrons as well as transport from the sunlit side. How differently do these processes influence the ionospheric densities? Is transport also influencing densities on the sunlit side? To address these questions, we have analyzed ion densities from the Ion and Neutral Mass Spectrometer (INMS) data from 16 close flybys of Titan's upper atmosphere. Looking at the local ionization frequencies associated with the two primary ions, N2+ and CH4+, calculated from an empirical model, we discuss their influence on ion number densities for both short-lived and long-lived ions at altitudes below 1200 km and interpret our findings in terms of ion source. For a given N2 local ionization frequency, we found that certain ions, such as CH5+, have higher densities on the dayside than on the darkside. We explain that this is due to the structure of the N2 photo-absorption cross-sections beyond the N2 ionization threshold, which allows CH4 ionization at lower altitudes. We present detailed modeling results to support our interpretation.

Sagnières, L. B. M.; Galand, M.; Cui, J.; Lavvas, P. P.; Vigren, E.; Vuitton, V.; Yelle, R. V.; Wellbrock, A.; Coates, A. J.

2014-04-01

243

R and D -- Seismic report on the influence of the source region on regional seismic waveforms as inferred from modeling  

SciTech Connect

The identification of an underground nuclear test from its seismic signal recorded by seismometers at regional distances is one of the fundamental scientific goals of the Comprehensive Test Ban Treaty R and D Program. The work being reported here addresses the issue of event discrimination through the use of computer models that use realistic simulations of nuclear explosions in various settings for the generation of near-regional and regional synthetic seismograms. The study exercises some unique, recently developed computer modeling capabilities that heretofore have not been available for discrimination studies. A variety of source conditions and regional paths are investigated. Under the assumptions of the study, conclusions are: (1) spall, non-linear deformation, and depth-of-burial do not substantially influence the near-regional signal and (2) effects due to basins along the regional path very much dominate over source region geology in influencing the signal at regional distances. These conclusions, however, are relevant only for the frequencies addressed, which span the range from 0.1 to 1 Hz for the regional calculations and 0.1 to 3 Hz for the near-regional calculations. They also are relevant only for the crudely ``China-like`` basin, crust, and mantle properties used in the study. If it is determined that further investigations are required, researchers may use this study as a template for such work.

App, F.N.; Jones, E.M.; Bos, R.J.

1997-11-01

244

Mercury emissions to the atmosphere from natural and anthropogenic sources in the Mediterranean region  

NASA Astrophysics Data System (ADS)

This report discusses past, current and projected mercury emissions to the atmosphere from major industrial sources, and presents a first assessment of the contribution to the regional mercury budget from selected natural sources. Emissions (1995 estimates) from fossil fuels combustion (29.8 t yr -1) , cement production (28.8 t yr -1) and incineration of solid wastes (27.6 t yr -1) , all together account for about 82% of the regional anthropogenic total (105.7 t yr -1) . Other industrial sources in the region are smelters (4.8 t yr -1) , iron-steel plants (4.8 t yr -1) and other minor sources (chlor-alkali plants, crematoria, chemicals production) that have been considered together in the miscellaneous category (9.6 t yr -1) . Regional emissions from anthropogenic sources increased at a rate of 3% yr-1 from 1983 to 1995 and are projected to increase at a rate of 1.9% yr-1 in the next 25 years, if no improvement in emission control policy occurs. On a country-by-country basis, France is the leading emitter country with 22.6 t yr -1 followed by Turkey (16.1 t yr -1) , Italy (11.4 t yr -1) , Spain (9.1 t yr -1) , the former Yugoslavia 7.9 ( t yr -1) , Morocco (6.9 t yr -1) , Bulgaria (6.8 t yr -1) , Egypt (6.1 t yr -1) , Syria (3.6 t yr -1) , Libya (2.9 t yr -1) , Tunisia (2.8 t yr -1) and Greece (2.7 t yr -1) , whereas the remaining countries account for less than 7% of the regional total. The annual emission from natural sources is 110 t yr -1, although this figure only includes the volatilisation of elemental mercury from surface waters and emissions from volcanoes, whereas the contribution due to the degassing of mercury from top soil and vegetation has not been included in this first assessment. Therefore, natural and anthropogenic sources in the Mediterranean region release annually about 215 t of mercury, which represents a significant contribution to the total mercury budget released in Europe and to the global atmosphere.

Pirrone, N.; Costa, P.; Pacyna, J. M.; Ferrara, R.

245

Morphology and Chemical composition of Atmospheric Particles over Semi-Arid region (Jaipur, Rajasthan) of India  

NASA Astrophysics Data System (ADS)

Uncertainties associated with the radiative forcing of atmospheric dust particles is highest, owing to lack of region-specific dust morphology (particle shape, size) and mineralogy (chemical composition) database, needed for modeling their optical properties (Mishra and Tripathi, 2008). To fill this gap for the Indian region, we collected atmospheric particles (with aerodynamic size <5um, PM5 and a few bulk particles; TSP) from seven sites of Jaipur and nearby locales (semi-arid region, in the vicinity of Thar Desert of Rajasthan) at varying altitude, during late winters of ca. 2012. PM5 particles were collected on Teflon filters (for bulk chemical analyses), while pure Tin substrates (~1×1 mm2) were used for investigating individual particle morphology. Using Scanning Electron Microscope equipped with Energy Dispersive X ray (SEM-EDX) facility at NPL, images of individual particles were recorded and the morphological parameters (e.g. Aspect ratio; AR, Circulatory parameter; CIR.) were retrieved following Okada et al. (2001), whereas chemical compositions of individual particles were determined by EDX and bulk samples by X ray fluorescence (XRF). The geometrical size distributions of atmospheric particles were generated for each site. Based on NIST (National Institute of Standard and Technology, USA) morphology database, the site-specific individual particle shapes reveal predominance of "Layered" (calcite and quartz rich), "Angular" structures (quartz rich) and "Flattened" particles over all the sites. Particles were found to be highly non-spherical with irregular shapes (CIR varying from 1 to 0.22 with median value ~0.76; AR varying from 1 to 5.4 with median value ~1.64). Noteworthy to mention, that unit values of AR and CIR represent spherical particles. Chemical analyses of PM5 particles revealed dominance of crustal elements e.g. Si, Al, Fe, Ca, Mg, in general. Particles over Kukas Hill (27.027° N, 75.919° E; ~800 MAGL) showed highest Fe mass fractions (~43%), i.e. a key element (in form of hematite; Fe2O3) for solar (visible) energy absorption and thus heating the atmosphere. The retrieved morphological parameters help to construct particle shape and number size distribution that are highly useful to reduce the uncertainty in radiative forcing of dust particles appreciably when combined with particle chemical composition as suggested by Kalashnikova and Sokolik (2004). References : Mishra, S. K., and S. N. Tripathi (2008), Modeling optical properties of mineral dust over the Indian Desert, J. Geophys. Res., 113, D23201, 19 PP., doi:10.1029/2008JD010048. Okada, K., J. Heintzenberg, K. Kai, and Y. Qin (2001), Shape of atmospheric mineral particles collected in three Chinese arid-regions, Geophys. Res. Lett., 28, 3123-3126 Kalashnikova OV, Sokolik IN. (2004) Modeling the radiative properties of nonspherical soil-derived mineral aerosols, J Quant Spectrosc Radiat Transfer, 87, 137-66.

Mishra, S. K.; Agnihotri, R.; Yadav, P.; Singh, S.; Tawale, J. S.; Rashmi, R.; Prasad, M.; Arya, B. C.; Mishra, N.

2012-12-01

246

A bulk similarity approach in the atmospheric boundary layer using radiometric skin temperature to determine regional surface fluxes  

Microsoft Academic Search

Profiles of wind velocity and temperature in the outer region of the atmospheric boundary layer (ABL) were used together with surface temperature measurements, to determine regional shear stress and sensible heat flux by means of transfer parameterizations on the basis of bulk similarity. The profiles were measured by means of radiosondes and the surface temperatures by infrared radiation thermometry over

Wilfried Brutsaert; Michiaki Sugita

1991-01-01

247

Himalayan Wintertime Climate Variability: Large-Scale Atmospheric Circulation and Regional Precipitation  

NASA Astrophysics Data System (ADS)

The future state of High Mountain Asia's (HMA) glaciers is of critical importance to water security throughout densely populated regions of Asia. Without understanding regional climatic influences, the prediction of terrestrial water fluxes is not possible. Glacier records in the eastern and central Himalaya (CH) yield some of the world's most rapid retreat rates. However, there are a number of steady state or positive mass-balance glaciers in the Karakoram and western Himalaya (KH) regions. The goal of this research is to investigate multi-annual variations in synoptic wintertime weather as a contributing factor to regional mass-balance trends. Winter Westerly Disturbances (WWD) are the primary climatic influence within HMA during the boreal winter. This research investigates variations and changes in WWD over the period 1979--2010 and relationships with extreme precipitation in the KH and CH using multiple datasets. It is demonstrated that extreme precipitation events occurring in the KH and CH are often spatiotemporally independent, suggesting differing behavior of WWD affecting each region. The wavelet power spectrum of 200hPa geopotential height anomalies is used to characterize the frequency and magnitude of individual disturbances and to distinguish synoptic scale variability through time. This analysis exhibits an enhancement in the strength and frequency of WWD in the KH and indicates an increase in local extreme precipitation events. In contrast, the CH is observed to experience weakening influence of these disturbances and consequently, a decrease in extreme precipitation. Additionally, peak melt season temperatures are observed to decrease (increase) in the KH (CH) during the study period. This study also investigates multi-annual variability of WWD and teleconnections with some known modes of climate variability affecting central Asia, including the Arctic Oscillation, the El Nino Southern Oscillation, and the Siberian High. Although there is clear evidence that these modes affect circulation and precipitation in HMA, their competing influences on WWD are complex and non-linear. These results suggest that a thorough understanding of WWD and their spatiotemporal variations are crucial to improve our knowledge of the hydrologic cycle within HMA as well as our ability to project the future status of Asia's water resources.

Cannon, Forest Glen

248

Influence of Sea Ice Dynamics on Atmospheric Mercury and Ozone Concentrations and Fluxes during the BROMEX Campaign  

NASA Astrophysics Data System (ADS)

We present results from the Bromine, Ozone, and Mercury (Hg) Experiment (BROMEX) study in Barrow, Alaska, near the Arctic Ocean where we assessed how changing sea ice dynamics may affect future Hg cycling. Atmospheric Mercury Depletion Events (AMDEs) whereby gaseous elemental Hg (GEM) is oxidized to gaseous oxidized Hg (GOM) and fine (< 2.5 ?m) particulate-bound Hg (PHg) are of concern for polar ecosystems as they lead to increased Hg deposition to underlying snow and ice surfaces. From March 15 - April 4 2012, we established two measurement sites. The first was Out-On-The-Ice (OOTI), located on the frozen Arctic Ocean and considered a possible hot-spot for AMDEs due to the high saline content of sea ice, approximately 2 km from the shore. Here, measurements included atmospheric Hg speciation (i.e, GEM, GOM, and PHg), surface exchange fluxes of GEM and ozone, along with meteorological parameters. At a second site, located 5 km inland, and co-located with several atmospheric halogen measurements, we measured atmospheric Hg speciation and ozone concentrations. Atmospheric Hg and ozone concentrations at the two sites tracked each other very closely, and showed pronounced temporal changes depending on sea ice conditions. During the initial period when the sea ice surrounding Barrow was completely closed for several weeks, GEM was generally depleted below 0.75 ng m-3 and on occasion dropped below detection limits (<0.05 ng m-3), PHg concentrations ranged from 50 pg m-3 to 240 pg m-3, and GOM ranged from 15 to 100 pg m-3. Ozone during that time also was depleted (generally below 10 ppb) showing typical patterns observed during polar AMDEs with coupled mercury and ozone depletion events. During a period when a lead opened in the sea ice upwind of the two sites, GEM increased to a maximum of 2.5 ng m-3, while PHg and GOM remained at similar levels to those during closed sea ice conditions. Upon refreezing of the open sea ice, atmospheric GEM concentrations again dropped to below detection limits within 24 hours while GOM rapidly increased to the highest concentrations of the campaign (226 pg m-3), before rapidly decreasing to below detection limits. The strong GEM depletion and highest GOM levels were possibly related to halogen-rich, newly-formed sea ice initiating strong regional AMDEs. The later decrease in GOM concentrations observed at both stations demonstrates that the air masses remained depleted in GEM and GOM for several days showing the large spatial scale of the Hg depletion in the boundary layer. Approximately 24-hour after AMDEs, we find a consistent GEM surface emission which we attribute to photochemical reduction of deposited Hg and re-emission to the atmosphere. Our data therefore indicates that rapid freezing and thawing of sea ice has the potential to substantially influence the arctic Hg cycle.

Moore, C. W.; Steffen, A.; Obrist, D.; Staebler, R. M.

2012-12-01

249

Lessons learned from the Bay Region Atmospheric Chemistry Experiment (BRACE) and implications for nitrogen management of Tampa Bay  

NASA Astrophysics Data System (ADS)

Results from air quality modeling and field measurements made as part of the Bay Region Atmospheric Chemistry Experiment (BRACE) along with related scientific literature were reviewed to provide an improved estimate of atmospheric reactive nitrogen (N) deposition to Tampa Bay, to apportion atmospheric N between local and remote sources, and to assess the impact of regulatory drivers on N deposition to Tampa Bay. Simulations using the Community Multiscale Air Quality model v4.4 modified with the University of California Davis aerosol module (CMAQ-UCD) provided a framework for this review. For 2002, CMAQ-UCD modeled atmospheric loading rates were 6910 metric tons N to the land surface of the watershed and 548 metric tons N to bay surface of the watershed, respectively. If an 18% transfer rate of atmospherically-deposited N from watershed to bay is assumed, then the corresponding atmospheric loading to Tampa Bay was 1790 metric tons N or 57% of the total N loading to the bay. From CMAQ-UCD modeling, oxidized N sources both within and outside Tampa Bay's watershed were important contributors to atmospheric N loading to the bay. Within the watershed, oxidized N emissions from mobile sources had a disproportionately larger impact than did power plant sources on atmospheric N loading. Predicted decreases in atmospheric N deposition to Tampa Bay by 2010 due to regulatory drivers were significant, and plausibly evident in recent declines in ambient air NOx concentrations in urban Tampa and St. Petersburg.

Poor, Noreen D.; Cross, Lindsay M.; Dennis, Robin L.

2013-05-01

250

Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge  

SciTech Connect

An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O{sub 2}/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion, Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China) and School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 137-701 (Korea, Republic of)

2011-10-15

251

Photoacoustic measurement of ammonia in the atmosphere: influence of water vapor and carbon dioxide  

SciTech Connect

The photoacoustic determination of the ammonia concentration in atmospheric air by absorption of CO{sub 2} laser radiation at 9.22 {mu}m is influenced by the presence of H{sub 2}O and CO{sub 2}. Kinetic cooling due to the coupling of excited CO{sub 2} and N{sub 2} levels causes important changes in phase and amplitude of the photoacoustic signal. Theoretical background is presented to deduce the correct NH{sub 3} concentration from the signal. The experimental setup used to perform field measurements is described. Adhesion of NH{sub 3} to the walls of the resonant photoacoustic cell was investigated. Temperature effects are treated. Field data of NH{sub 3} and H{sub 2}O concentrations are presented. Key words: Photoacoustics, ammonia, kinetic cooling, trace gas measurements, ammonia adhesion, acoustic resonance, CO{sub 2} laser radiation, water vapor absorption, carbon dioxide absorption.

Rooth, R.A.; Verhage, A.J.L.; Wouters, L.W. (N. V. Tot Keuring van Elektrotechnische Materialen, Postbus 9035, NL-6800 ET Arnhem (The Netherlands))

1990-09-01

252

Photoacoustic measurement of ammonia in the atmosphere: influence of water vapor and carbon dioxide.  

PubMed

The photoacoustic determination of the ammonia concentration in atmospheric air by absorption of CO(2) laser radiation at 9.22 microm is influenced by the presence of H(2)O and CO(2). Kinetic cooling due to the coupling of excited CO(2) and N(2) levels causes important changes in phase and amplitude of the photoacoustic signal. Theoretical background is presented to deduce the correct NH(3) concentration from the signal. The experimental setup used to perform field measurements is described. Adhesion of NH(3) to the walls of the resonant photoacoustic cell was investigated. Temperature effects are treated. Field data of NH(3) and H(2)O concentrations are presented. PMID:20567465

Rooth, R A; Verhage, A J; Wouters, L W

1990-09-01

253

Seasonal and regional air quality and atmospheric deposition in the eastern United States  

NASA Astrophysics Data System (ADS)

The atmospheric concentration, wet deposition, and inferred dry deposition of selected air pollutants reported over two 5-year periods in the 1990s at or near 34 rural Clean Air Status and Trends Network (CASTNET) sites located in the eastern United States (U.S.) are adjusted for known biases, composed into seasonal values, and examined. Several terms are defined for the current study, where OxN is the measured oxidized nitrogen (i.e., airborne OxN is the sum of airborne HNO3 and NO3-, expressed as nitrogen), NH4 is the measured reduced nitrogen (i.e., airborne NH4 is the aerosol NH4+, expressed as nitrogen), N is the sum of measured oxidized and reduced forms of nitrogen, expressed as nitrogen, and S is the measured oxidized sulfur (i.e., airborne S is the sum of airborne SO2 and SO42-, expressed as sulfur). The atmospheric NH3 concentration is not monitored in the current study. Similar patterns of seasonal and regional behavior are found consistently in both periods. In the east, atmospheric concentration, estimated deposition velocity, precipitation rate, inferred dry deposition, wet deposition, and total (dry plus wet) deposition estimates of each of the monitored chemical constituents display regular seasonal cycles of behavior. High and low seasonal values occur in summer and winter, respectively, for atmospheric concentration and dry deposition of SO42-, NH4+, O3, HNO3, and N; for dry OxN deposition; for wet S and H+ deposition; and for total OxN and N deposition. In contrast, high seasonal values of SO2 concentration and dry deposition, and atmospheric NO3- concentration occur in winter. In the east, SO2 composes a major portion (?70%) of the atmospheric S concentration and is the dominant (>85%) contributor to dry S deposition. Although aerosol NH4+ represents a major portion of the measured atmospheric N concentration (?67%), HNO3 dominates estimates of both dry OxN (>90%) and N (>75%) deposition. Dry deposition contributes ?15%, 38%, and 43% to total deposition of NH4, OxN, and S, and these appear to be conservative estimates. Wet deposition is a major contributor to total deposition, generally peaking in summer or spring. Total S, OxN, and N deposition peak in summer. Although mean O3 concentration is ?70% larger in summer than winter, dry O3 deposition estimates in the east are >5 times higher in summer. Within the uncertainty of current conservative estimates, dry deposition of SO42-, HNO3, OxN, N, and O3 appears to be highest at the high-elevation subset of sites. This underscores the potential importance of dry deposition as a stressor to high-elevation ecosystems in the eastern U.S.

Sickles, Joseph E.; Shadwick, Douglas S.

2007-09-01

254

Impact of Atmospheric Infrared Sounder (AIRS) Thermodynamic Profiles on Regional Precipitation Forecasting  

NASA Technical Reports Server (NTRS)

In data sparse regions, remotely-sensed observations can be used to improve analyses and lead to better forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), provides temperature and moisture profiles in clear and cloudy regions with accuracy which approaches that of radiosondes. The purpose of this paper is to describe an approach to assimilate AIRS thermodynamic profile data into a regional configuration of the Advanced Research WRF (ARW) model using WRF-Var. Quality indicators are used to select only the highest quality temperature and moisture profiles for assimilation in clear and partly cloudy regions, and uncontaminated portions of retrievals above clouds in overcast regions. Separate error characteristics for land and water profiles are also used in the assimilation process. Assimilation results indicate that AIRS profiles produce an analysis closer to in situ observations than the background field. Forecasts from a 37-day case study period in the winter of 2007 show that AIRS profile data can lead to improvements in 6-h cumulative precipitation forecasts resulting from improved thermodynamic fields. Additionally, in a convective heavy rainfall event from February 2007, assimilation of AIRS profiles produces a more unstable boundary layer resulting in enhanced updrafts in the model. These updrafts produce a squall line and precipitation totals that more closely reflect ground-based observations than a no AIRS control forecast. The location of available high-quality AIRS profiles ahead of approaching storm systems is found to be of paramount importance to the amount of impact the observations will have on the resulting forecasts.

Chou, S.-H.; Zavodsky, B. T.; Jedloved, G. J.

2010-01-01

255

Climatological simulations of ozone and atmospheric aerosols in the Greater Cairo region  

SciTech Connect

An integrated chemistry-climate model (RegCM4-CHEM) simulates present-day climate, ozone and tropospheric aerosols over Egypt with a focus on Greater Cairo (GC) region. The densley populated GC region is known for its severe air quality issues driven by high levels of anthropogenic pollution in conjuction with natural sources such as dust and agricultural burning events. We find that current global emission inventories underestimate key pollutants such as nitrogen oxides and anthropogenic aerosol species. In the GC region, average-ground-based NO2 observations of 40-60 ppb are substantially higher than modeled estimates (5-10 ppb), likely due to model grid resolution, improper boundary layer representation, and poor emissions inventories. Observed ozone concentrations range from 35 ppb (winter) to 80 ppb (summer). The model reproduces the seasonal cycle fairly well, but modeled summer ozone is understimated by approximately 15 ppb and exhibits little interannual variability. For aerosols, springtime dust events dominate the seasonal aerosol cycle. The chemistry-climate model captures the springtime peak aerosol optical depth (AOD) of 0.7-1 but is slightly greater than satellite-derived AOD. Observed AOD decreases in the summer and increases again in the fall due to agricultural burning events in the Nile Delta, yet the model underestimates this fall observed AOD peak, as standard emissions inventories underestimate this burning and the resulting aerosol emissions. Our comparison of modeled gas and particulate phase atmospheric chemistry in the GC region indicates that improved emissions inventories of mobile sources and other anthropogenic activities are needed to improve air quality simulations in this region.

Steiner, A. L.; Tawfik, A. B.; Shalaby, A.; Zakey, A. S.; Abdel Wahab, M. M.; Salah, Z.; Solmon, F.; Sillman, S.; Zaveri, Rahul A.

2014-04-16

256

Grassland/atmosphere response to changing climate: Coupling regional and local scales. Final report  

SciTech Connect

The objectives of the study were: to evaluate the response of grassland ecosystems to atmospheric change at regional and site scales, and to develop multiscaled modeling systems to relate ecological and atmospheric models with different spatial and temporal resolutions. A menu-driven shell was developed to facilitate use of models at different temporal scales and to facilitate exchange information between models at different temporal scales. A detailed ecosystem model predicted that C{sub 3} temperate grasslands wig respond more strongly to elevated CO{sub 2} than temperate C{sub 4} grasslands in the short-term while a large positive N-PP response was predicted for a C{sub 4} Kenyan grassland. Long-term climate change scenarios produced either decreases or increases in Colorado plant productivity (NPP) depending on rainfall, but uniform increases in N-PP were predicted in Kenya. Elevated CO{sub 2} is likely to have little effect on ecosystem carbon storage in Colorado while it will increase carbon storage in Kenya. A synoptic climate classification processor (SCP) was developed to evaluate results of GCM climate sensitivity experiments. Roughly 80% agreement was achieved with manual classifications. Comparison of lx and 2xCO{sub 2} GCM Simulations revealed relatively small differences.

Coughenour, M.B.; Kittel, T.G.F.; Pielke, R.A.; Eastman, J.

1993-10-01

257

Health risk assessment for residents exposed to atmospheric diesel exhaust particles in southern region of Taiwan  

NASA Astrophysics Data System (ADS)

Evidence shows a strong association among air pollution, oxidative stress (OS), deoxyribonucleic acid (DNA) damage, and diseases. Recent studies indicated that the aging, human neurodegenerative diseases and cancers resulted from mitochondrial dysfunction and OS. The purpose of this study is to provide a probabilistic risk assessment model to quantify the atmospheric diesel exhaust particles (DEP)-induced pre-cancer biomarker response and cancer incidence risk for residents in south Taiwan. We conducted entirely monthly particulate matter sampling data at five sites in Kaohsiung of south Taiwan in the period 2002-2003. Three findings were found: (i) the DEP dose estimates and cancer risk quantification had heterogeneously spatiotemporal difference in south Taiwan, (ii) the pre-cancer DNA damage biomarker and cancer incidence estimates had a positive yet insignificant association, and (iii) all the estimates of cancer incidence in south Taiwan populations fell within and slight lower than the values from previous cancer epidemiological investigations. In this study, we successfully assessed the tumor incidence for residents posed by DEP exposure in south Taiwan compared with the epidemiological approach. Our approach provides a unique way for assessing human health risk for residences exposed to atmospheric DEP depending on specific combinations of local and regional conditions. Our work implicates the importance of incorporating both environmental and health risk impacts into models of air pollution exposure to guide adaptive mitigation strategies.

Chio, Chia-Pin; Liao, Chung-Min; Tsai, Ying-I.; Cheng, Man-Ting; Chou, Wei-Chun

2014-03-01

258

Influence of aerosol loading, water vapor and surface topography trends on the regional hydrology of the Indo-Ganges basin  

NASA Astrophysics Data System (ADS)

Satellite based measurements show high concentrations of aerosols (aerosol optical depth) over the Indo-Ganges basin. However, little is known about the vertical structure and distribution of the aerosols in this region. In addition the direct (microphysical) and indirect (radiative) influence of aerosols on the regional water vapor characteristics and cloud formation over different land cover and surface elevations remains uncertain. Previous studies have shown that carbonaceous aerosol can absorb incoming solar radiation, warming the aerosol layer and hence reduce the solar radiation reaching the surface. This in turn reduces the surface temperature, heat and moisture fluxes and increases the stability of the boundary layer resulting in slower regional hydrological cycle. However, on a microphysical scale the aerosols, as cloud condensation nuclei, tend to enhance the cloud formation, although the resulting cloud droplets are slower to coalesce and to form into precipitation. This study utilizes a combination of ground based measurements collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Program Ganges Valley Aerosol Experiment's (GVAX) and satellite based measurements collected by remote sensors (MODIS, CALIPSO) to carefully evaluate the potential effects of aerosol on the regional hydrology of the Ganges Valley. The study investigates how aerosol and water vapor properties (spatial and vertical distribution, aerosol speciation, etc.) differ between the Ganges valley, lowlands, and neighboring mountainous region and whether this difference enhances or suppresses the regional convective initiation and precipitation.

Manoharan, V.; Cadeddu, M. P.

2012-12-01

259

Analyzing the Influence of Tropical Deforestation on the Northern Hemisphere Climate Through Atmospheric Teleconnections  

NASA Astrophysics Data System (ADS)

Previous studies have identified the regional-scale climate response to tropical deforestation through changes to the biophysical exchanges of water, energy, and momentum between the land surface and the atmosphere; however, little is known about the effects of tropical deforestation on the global climate. Current research has focused on climate responses in the extratropics with little analyses of the mechanisms responsible for propagating the signal out of the tropics. Here, we present a detailed study of the physical processes important in propagating a signal resulting from deforestation out of the tropics to the Northern Hemisphere in winter. Through complete deforestation of the tropics we analyze changes to the deep moist convection and reductions in high-level outflow as well as the anomalous forcing of Rossby waves out of the tropics. Our study indicates that an anomalous Rossby wave forcing resulting from tropical deforestation modifies the East Asian Jet strength and structure as well as other features of the Northern Hemisphere mean circulation patterns. Furthermore, our results indicate that tropical deforestation can amplify different modes of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) through a redistribution of atmospheric mass caused by fundamental changes to the strength and positioning of the storm tracks and synoptic eddy activity. Different modes of variability cause different climate responses across Siberia and result in anomalous changes to the low-level winds that can significantly enhance the advection of warm air into Eurasia from the south and west. While theoretical, our approach illustrates the potentially important processes connecting regional-scale changes in the tropical climate to regional-scale changes in the extratropics.

Snyder, P. K.; Hitchman, M. H.; Foley, J. A.

2004-12-01

260

Tillage and N-source influence soil-emitted nitrous oxide in the Alberta Parkland region  

SciTech Connect

Zero tillage systems are receiving attention as possible strategies for sequestering atmospheric carbon. This benefit may be offset by increased N2O emissions, which have been reported for soils under zero tillage (ZT) compared to those under more intensive tillage (IT). Comparisons of N2O emissions from the two systems have been restricted to the growing season, but substantial losses of N2O have been reported during spring thaw events in many regions. Inorganic and organic additions of nitrogen and fallowing have also been shown to increase levels of soil-emitted N2O. The objectives for this study were: (i) to confirm that losses of N2O are higher under ZT than under IT in Alberta Parkland agroecosystems; (ii) to compare the relative influence of urea fertilizer (56 or 100 kg N h--1), field pea residue (dry matter at 5 Mg h--1), sheep manure (dry matter at 40 Mg h--1) additions, and fallow on total N2O losses; and (iii) to investigate possible interactions between fertility and tillage treatments. Gas samples were collected using vented soil covers at three sites near Edmonton, Alberta during 1993, 1994, and 1995. Gas samples were analyzed using a gas chromatograph equipped with a 63Ni electron capture detector. Estimated annual N2O loss ranged from 0.1 to 4.0 kg N ha-1. Emissions during summer were slightly higher, similar, or lower on ZT compared to those under IT, but were consistently lower on ZT plots during spring thaw. Combined estimates (spring plus summer) of N2O loss under ZT were equal to or lower than those under IT. Highest overall losses were observed on fallow plots, followed by fertilizer, pea residue, and then either manure or control plots. We conclude that ZT management systems have potential for reducing agricultural greenhouse gas emissions in the Alberta Parkland region.

Lemke , R L.; Izaurralde, R Cesar C.; Nyborg, M.; Solberg, E D.

1999-01-01

261

Comparative influence of spatial scale on beta diversity within regional  

E-print Network

assemblages of birds and butterflies Ralph Mac Nally1 , Erica Fleishman2 *, Lesley P. Bulluck3 butterflies in the Great Basin of North America depended on sampling grain (the smallest resolvable unit methods for birds and butterflies in temperate regions. Data were compiled at three sampling grains, sites

262

Influence of changed vegetations fields on regional climate simulations in the Barents Sea Region  

Microsoft Academic Search

In the context of the EU-Project BALANCE (http:\\/\\/balance-eu.info) the regional climate model REMO was used for extensive calculations of the Barents Sea climate to investigate the vulnerability\\u000a of this region to climate change. The regional climate model REMO simulated the climate change of the Barents Sea Region between\\u000a 1961 and 2100 (Control and Climate Change run, CCC-Run). REMO on ~50 km

Holger Göttel; Jörn Alexander; Elke Keup-Thiel; Diana Rechid; Stefan Hagemann; Tanja Blome; Annett Wolf; Daniela Jacob

2008-01-01

263

Titan's hydrodynamically escaping atmosphere: Escape rates and the structure of the exobase region  

NASA Astrophysics Data System (ADS)

In Strobel [Strobel, D.F., 2008. Icarus, 193, 588-594] a mass loss rate from Titan's upper atmosphere, ˜4.5×10 amus, was calculated for a single constituent, N 2 atmosphere by hydrodynamic escape as a high density, slow outward expansion driven principally by solar UV heating due to CH 4 absorption. It was estimated, but not proven, that the hydrodynamic mass loss is essentially CH 4 and H 2 escape. Here the individual conservation of momentum equations for the three major components of the upper atmosphere (N 2, CH 4, H 2) are solved in the low Mach number limit and compared with Cassini Ion Neutral Mass Spectrometer (INMS) measurements to demonstrate that light gases (CH 4, H 2) preferentially escape over the heavy gas (N 2). The lightest gas (H 2) escapes with a flux 99% of its limiting flux, whereas CH 4 is restricted to ?75% of its limiting flux because there is insufficient solar power to support escape at the limiting rate. The respective calculated H 2 and CH 4 escape rates are 9.2×10 and 1.7×10 s, for a total of ˜4.6×10 amus. From the calculated densities, mean free paths of N 2, CH 4, H 2, and macroscopic length scales, an extended region above the classic exobase is inferred where frequent collisions are still occurring and thermal heat conduction can deliver power to lift the escaping gas out of the gravitational potential well. In this region rapid acceleration of CH 4 outflow occurs. With the thermal structure of Titan's thermosphere inferred from INMS data by Müller-Wodarg et al. [Müller-Wodarg, I.C.F., Yelle, R.V., Cui, J., Waite Jr., J.H., 2008. J. Geophys. Res. 113, doi:10.1029/2007JE003033. E10005], in combination with calculated temperature profiles that include sputter induced plasma heating at the exobase, it is concluded that on average that the integrated, globally average, orbit-averaged, plasma heating rate during the Cassini epoch does not exceed ˜5×10 eVcms ( ˜0.0008 ergcms).

Strobel, Darrell F.

2009-08-01

264

Vertical structure of cloud layers in the atmospheres of giant planets. I. On the influence of variations of some atmospheric parameters on the vertical structure characteristics  

NASA Astrophysics Data System (ADS)

The influence of variations in the parameters, determining the physical properties of a medium, on the characteristics of the vertical structure of clouds in the Jovian atmosphere has been studied. The data from spectrophotometric measurements of Jupiter carried out in the spectral range from 500 to 900 nm during 1993 were processed. The analysis was performed with the method suggested by A.V. Morozhenko. We used a special software that was developed to define the behavior of the aerosol scattering component of the effective optical thickness versus the depth in a semi-infinite atmosphere. Spectral absorption bands of the atmospheric gas were considered. The characteristics of the vertical structure of the aerosol component of the Jovian atmosphere averaged over the planetary disk were determined: in the atmospheric layer with a pressure ranging from 0.12 to 1.3 bar, the volume density of the aerosol cloud first rapidly increases and then gently reaches its maximum; from 1.3 to 4.0 bar, the aerosol cloud becomes extremely rarefied; from 4.0 to 15.0 bar, there are no indications of significant aerosol inclusions.

Ovsak, A. S.

2015-01-01

265

Atmosphere  

NASA Astrophysics Data System (ADS)

This paper investigates the high-temperature corrosion behavior of microstructurally different regions of the weldment of 9 Cr-1 Mo steel used in thermal power plant boiler in SO2 + O2 environment. The weldment is produced by tungsten inert gas welding method, and the different regions of the weldment (weld metal, heat-affected zone, and base metal) are exposed in SO2 + O2 (ratio 2:1) environment at 973 K for 120 h. The reaction kinetics and corrosion growth rate of different regions of weldment in isothermal condition are evaluated. The post corroded scales of the different specimens are studied in SEM, EDS, and XRD. The results indicate that the weld metal shows higher corrosion rate followed by HAZ and base metal. The higher rate of corrosion of weldmetal is mainly attributed to the least protective inner scale of Cr2O3 with minimum Cr Content. This is due to the formation of delta ferrite, which leads to the precipitation of the Cr-based secondary phases and depletes the free Cr from the matrix. The thermal cycles during welding at high temperature are favorable for the formation of delta ferrite. On the other hand, in absence of delta ferrite, the base metal and HAZ regions of the weldment show lower corrosion rate than weld metal. The difference in corrosion rate in the three regions of the weldment is supplemented by post-corroded scale characterizations.

Ghosh, D.; Mitra, S. K.

2014-05-01

266

Atmospheric deposition of mercury and methylmercury to landscapes and waterbodies of the Athabasca oil sands region.  

PubMed

Atmospheric deposition of metals originating from a variety of sources, including bitumen upgrading facilities and blowing dusts from landscape disturbances, is of concern in the Athabasca oil sands region of northern Alberta, Canada. Mercury (Hg) is of particular interest as methylmercury (MeHg), a neurotoxin which bioaccumulates through foodwebs, can reach levels in fish and wildlife that may pose health risks to human consumers. We used spring-time sampling of the accumulated snowpack at sites located varying distances from the major developments to estimate winter 2012 Hg loadings to a ?20 000 km(2) area of the Athabasca oil sands region. Total Hg (THg; all forms of Hg in a sample) loads were predominantly particulate-bound (79 ± 12%) and increased with proximity to major developments, reaching up to 1000 ng m(-2). MeHg loads increased in a similar fashion, reaching up to 19 ng m(-2) and suggesting that oil sands developments are a direct source of MeHg to local landscapes and water bodies. Deposition maps, created by interpolation of measured Hg loads using geostatistical software, demonstrated that deposition resembled a bullseye pattern on the landscape, with areas of maximum THg and MeHg loadings located primarily between the Muskeg and Steepbank rivers. Snowpack concentrations of THg and MeHg were significantly correlated (r = 0.45-0.88, p < 0.01) with numerous parameters, including total suspended solids (TSS), metals known to be emitted in high quantities from the upgraders (vanadium, nickel, and zinc), and crustal elements (aluminum, iron, and lanthanum), which were also elevated in this region. Our results suggest that at snowmelt, a complex mixture of chemicals enters aquatic ecosystems that could impact biological communities of the oil sands region. PMID:24873895

Kirk, Jane L; Muir, Derek C G; Gleason, Amber; Wang, Xiaowa; Lawson, Greg; Frank, Richard A; Lehnherr, Igor; Wrona, Fred

2014-07-01

267

Regional Climate Simulations with COSMO-CLM for West Africa using different soil-vegetation-atmosphere-transfer module's (SVAT's)  

NASA Astrophysics Data System (ADS)

Climate predictions on decadal timescales constitute a new field of research, closing the gap between short-term and seasonal weather predictions and long-term climate projections. Therefore, the Federal Ministry of Education and Research in Germany (BMBF) has recently funded the research program MiKlip (Mittelfristige Klimaprognosen), which aims to create a model system that can provide reliable decadal climate forecasts. Recent studies have suggested that one region with high potential decadal predictability is West Africa. Therefore, the DEPARTURE project (DEcadal Prediction of African Rainfall and ATlantic HURricanE Activity) was established within the MiKlip program to assess the feasibility and the potential added value of regional decadal climate predictions for West Africa. To quantify the potential decadal climate predictability, a multi-model approach with the three different regional climate models REMO, WRF and COSMO-CLM (CCLM) will be realized. The presented research will contribute to DEPARTURE by performing hindcast ensemble simulations with CCLM, based on SST-driven global MPI-ESM-LR simulations. Thereby, one focus is on the dynamic soil-vegetation-climate interaction on decadal timescales. Recent studies indicate that there are significant feedbacks between the land-surface and the atmosphere, which might influence the decadal climate variability substantially. To investigate this connection, three different SVAT's (TERRA_ML, Community Land Model (CLM), and VEG3D) will be coupled with the CCLM. Thus, sensitive model parameters shall be identified, whereby the understanding of important processes might be improved. As a first step, the influence of the model domain on the CCLM results was examined. For this purpose, recent CCLM results from simulations for the official CORDEX domain were compared with CCLM results achieved by using an extended DEPARTURE model domain to about 60°W. This sensitivity analysis was performed with a horizontal resolution of 0.44°. Thereby, the analysis showed that the domain size doesn't affect the quality of the simulation results significantly. The impact of different SVAT's on the model performance is supposed to be higher. To investigate this assumption, TERRA_ML, the standard SVAT implemented in CCLM, is replaced by VEG3D using the OASIS3-MCT coupling software. Compared to TERRA_ML, VEG3D includes an explicit vegetation layer, inducing higher correlations with observations as it has been shown in previous studies. The results of both model configurations are analysed and presented for the DEPARTURE model domain.

Breil, Marcus; Panitz, Hans-Jürgen

2013-04-01

268

About the Influence of the initial Atmosphere on the Earth's Temperature Distribution during it's Accumulation  

NASA Astrophysics Data System (ADS)

We suggested a new model for accumulation of planets of the Earth's group [1], which is based on the contemporary results of geochemical analyses, which allow to obtain the concentrations of short living radioactive isotopes of 26Al in the matter of the pre planet cloud [2]. With use of that data new estimations of temperature distribution into the growing planetary pre planetary bodies into the Earth's nebular zone had been obtained. For the further Earth's temperature evolution, as it had been showed by the results of numerical modeling, the main role belongs to the temperature distribution in the forming Earth's core and the existence of a dense and transparent atmosphere. The shadow influence of the initial atmosphere had been researched in the paper [3]. We shall give the main consideration to these problems in that paper. It had been shown in [1], that on the earliest accumulation stage the heat release by the decay of 26Al it is sufficient for forming a central melted area and solid relatively thin mainly silicate upper envelope in the pre planetary body, with dimensions, larger than (50-100) km. The impact velocities on that stage are yet not large, therefore by the bodies impact with these or near dimensions liquid and mainly iron their parts merge, but the masses of the pre planetary bodies are not sufficient to gravitational keeping of silicate parts of the cold solid envelope. On that stage they remain into the nebular zone of the proto planet and the mechanism of matter differentiation for the future core and mantle reservoirs realizes. The process takes place yet in small bodies and is in time to finish during less than 10 million years. The next forming of the core and mantle structure continues according to all known estimations about 100 million years. Because of the merging of inner liquid parts of impacting bodies occur due to inelastic impact, the main part of potential energy transforms into heat. That continues up to that time when the iron core mass increases to the main part of the contemporary mass. The silicate particles of different dimensions remain in the proto planet cloud and in the initial atmosphere, reducing it's transparency and release of the heat radiation. On the finishing stage of the core growing the mass of the pre planetary body is sufficient for keeping of the rising part of the silicate envelope of falling bodies. The matter of the growing planet enriches more and more with a touch of silicates. The impact process of accumulated bodies gradually converts to the mechanism of elastic impact, by which only a small part of kinetic energy transforms into the merging by the pre planet body heat. The atmosphere losses the silicate particles and it's transparency exceeds. It is forming either a non melted mantle, or a mantle with a rising melted layer. That results show that the existence of a dense, nontransparent atmosphere leads to temperature growing in the inner areas of the planet during it's accumulation process. 1.Anfilogov V.N., Khachay Yu.V. A possible variant of matter differentiation on the initial stage of Earth's forming. // DAN. 2005, V. 403, N. 6, 803-806. 2.Merk R.,Breuer D., Spohn T., 2002. Numerical modeling of 26Al - Induced radioactive melting of asteroids concerning accretion, Icarus, 159, 183-191. 3.Hayashi C., Nakazawa K., Mizuno H. Earth's melting due to the blanketing effect of primordial dense atmosphere. // Earth and Plenetary Science Letters. (1979). v. 43, 22-28

Khachay, Y.; Anfilogov, V.; Antipin, A.

2012-04-01

269

Trans-Pacific and regional atmospheric transport of polycyclic aromatic hydrocarbons and pesticides in biomass burning emissions to western North America.  

PubMed

The trans-Pacific and regional North American atmospheric transport of polycyclic aromatic hydrocarbons (PAHs) and pesticides in biomass burning emissions was measured in air masses from April to September 2003 at two remote sites in western North America. Mary's Peak Observatory (MPO) is located in Oregon's Coast Range and Cheeka Peak Observatory (CPO) is located on the tip of the Olympic Peninsula in Washington State. During this time period, both remote sites were influenced by PAH and pesticide emissions from forest fires in Siberia and regional fires in Oregon and Washington State. Concurrent samples were taken at both sites on June 2 and August 4, 2003. On these dates, CPO had elevated gas phase PAH, alpha-hexachlorocyclohexane, and retene concentrations (p < 0.05) and MPO had elevated retene, particulate phase PAH, and levoglucosan concentrations due to trans-Pacific transport of emissions from fires in Siberia. In addition, during the April to September 2003 sampling period, CPO and MPO were influenced by emissions from regional fires that resulted in elevated levoglucosan, dacthal, endosulfan, and gas phase PAH concentrations. Burned and unburned forest soil samples collected from the regional forest fire area showed that 34-100% of the pesticide mass was lost from soil due to burning. These data suggest that the trans-Pacific and regional atmospheric transport of biomass burning emissions results in elevated PAH and pesticide concentrations in western North America. The elevated pesticide concentrations are likely due to re-emission of historically deposited pesticides from the soil and vegetation during the fire event. PMID:19320158

Genualdi, Susan A; Killin, Robert K; Woods, Jim; Wilson, Glenn; Schmedding, David; Simonich, Staci L Massey

2009-02-15

270

Development and validation of a regional coupled atmosphere lake model for the Caspian Sea Basin  

NASA Astrophysics Data System (ADS)

We present a validation analysis of a regional climate model coupled to a distributed one dimensional (1D) lake model for the Caspian Sea Basin. Two model grid spacings are tested, 50 and 20 km, the simulation period is 1989-2008 and the lateral boundary conditions are from the ERA-Interim reanalysis of observations. The model is validated against atmospheric as well as lake variables. The model performance in reproducing precipitation and temperature mean seasonal climatology, seasonal cycles and interannual variability is generally good, with the model results being mostly within the observational uncertainty range. The model appears to overestimate cloudiness and underestimate surface radiation, although a large observational uncertainty is found in these variables. The 1D distributed lake model (run at each grid point of the lake area) reproduces the observed lake-average sea surface temperature (SST), although differences compared to observations are found in the spatial structure of the SST, most likely as a result of the absence of 3 dimensional lake water circulations. The evolution of lake ice cover and near surface wind over the lake area is also reproduced by the model reasonably well. Improvements resulting from the increase of resolution from 50 to 20 km are most significant in the lake model. Overall the performance of the coupled regional climate—1D lake model system appears to be of sufficient quality for application to climate change scenario simulations over the Caspian Sea Basin.

Turuncoglu, Ufuk Utku; Elguindi, Nellie; Giorgi, Filippo; Fournier, Nicolas; Giuliani, Graziano

2013-10-01

271

Seasonal and spatial variations of atmospheric trace elemental deposition in the Aliaga industrial region, Turkey  

NASA Astrophysics Data System (ADS)

Atmospheric bulk deposition (wet + dry deposition) samples (n = 40) were collected concurrently at ten sites in four seasons between June 2009 and April 2010 in the Aliaga heavily industrialized region, Turkey, containing a number of significant air pollutant sources. Analyses of trace elements were carried out using inductively coupled plasma-mass spectrometry (ICP-MS). While there were significant differences in the particulate matter (PM) deposition fluxes among the sampling sites, seasonal variations were not statistically significant (Kruskal-Wallis test, p < 0.05). Both PM deposition and elemental fluxes were increased at the sampling sites in the vicinity of industrial activities. The crustal elements (i.e., Ca, Mg) and some anthropogenic elements (such as Fe, Zn, Mn, Pb, Cu, and Cr) were high, and the highest fluxes were mostly measured in summer and winter seasons. The enrichment factor (EF) and principal component analysis (PCA) was applied to the data to determine the possible sources in the study area. High EF values were obtained for the anthropogenic elements such as Ag, Cd, Zn, Pb, Cu and Sb. The possible sources were identified as anthropogenic sources (i.e., iron-steel production) (45.4%), crustal and re-suspended dust (27.1%), marine aerosol (7.9%), and coal and wood combustion (8.2%). Thus, the iron-steel production and its related activities were found to be the main pollutant sources for this region.

Kara, Melik; Dumanoglu, Yetkin; Altiok, Hasan; Elbir, Tolga; Odabasi, Mustafa; Bayram, Abdurrahman

2014-11-01

272

Influence of the vertical structure of the atmosphere on the seasonal variation of precipitable water and greenhouse effect  

Microsoft Academic Search

By using satellite observations and European Centre for Medium Range Weather Forecasts analyses, we study the seasonal variations of the precipitable water and the greenhouse effect, defined as the normalized difference between the longwave flux emitted at the surface and that emergent at the top of the atmosphere. Results show a strong systematic influence of the vertical structure of the

Sandrine Bony; Jean-Philippe Duvel

1994-01-01

273

Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism  

NASA Astrophysics Data System (ADS)

We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight countries are known to have nuclear weapons, 2 are constructing them, and an additional 32 nations already have the fissile material needed to build substantial arsenals of low-yield (Hiroshima-sized) explosives. Population and economic activity worldwide are congregated to an increasing extent in megacities, which might be targeted in a nuclear conflict. We find that low yield weapons, which new nuclear powers are likely to construct, can produce 100 times as many fatalities and 100 times as much smoke from fires per kt yield as previously estimated in analyses for full scale nuclear wars using high-yield weapons, if the small weapons are targeted at city centers. A single "small" nuclear detonation in an urban center could lead to more fatalities, in some cases by orders of magnitude, than have occurred in the major historical conflicts of many countries. We analyze the likely outcome of a regional nuclear exchange involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal). We find that such an exchange could produce direct fatalities comparable to all of those worldwide in World War II, or to those once estimated for a "counterforce" nuclear war between the superpowers. Megacities exposed to atmospheric fallout of long-lived radionuclides would likely be abandoned indefinitely, with severe national and international implications. Our analysis shows that smoke from urban firestorms in a regional war would rise into the upper troposphere due to pyro-convection. Robock et al. (2007) show that the smoke would subsequently rise deep into the stratosphere due to atmospheric heating, and then might induce significant climatic anomalies on global scales. We also anticipate substantial perturbations of global ozone. While there are many uncertainties in the predictions we make here, the principal unknowns are the type and scale of conflict that might occur. The scope and severity of the hazards identified pose a significant threat to the global community. They deserve careful analysis by governments worldwide advised by a broad section of the world scientific community, as well as widespread public debate.

Toon, O. B.; Turco, R. P.; Robock, A.; Bardeen, C.; Oman, L.; Stenchikov, G. L.

2007-04-01

274

Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism  

NASA Astrophysics Data System (ADS)

We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight countries are known to have nuclear weapons, 2 are constructing them, and an additional 32 nations already have the fissile material needed to build substantial arsenals of low-yield (Hiroshima-sized) explosives. Population and economic activity worldwide are congregated to an increasing extent in megacities, which might be targeted in a nuclear conflict. Our analysis shows that, per kiloton of yield, low yield weapons can produce 100 times as many fatalities and 100 times as much smoke from fires as high-yield weapons, if they are targeted at city centers. A single "small'' nuclear detonation in an urban center could lead to more fatalities, in some cases by orders of magnitude, than have occurred in the major historical conflicts of many countries. We analyze the likely outcome of a regional nuclear exchange involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal). We find that such an exchange could produce direct fatalities comparable to all of those worldwide in World War II, or to those once estimated for a "counterforce'' nuclear war between the superpowers. Megacities exposed to atmospheric fallout of long-lived radionuclides would likely be abandoned indefinitely, with severe national and international implications. Our analysis shows that smoke from urban firestorms in a regional war would rise into the upper troposphere due to pyro-convection. Robock et al. (2006) show that the smoke would subsequently rise deep into the stratosphere due to atmospheric heating, and then might induce significant climatic anomalies on global scales.We also anticipate substantial perturbations of global ozone. While there are many uncertainties in the predictions we make here, the principal unknowns are the type and scale of conflict that might occur. The scope and severity of the hazards identified pose a significant threat to the global community. They deserve careful analysis by governments worldwide advised by a broad section of the world scientific community, as well as widespread public debate.

Toon, O. B.; Turco, R. P.; Robock, A.; Bardeen, C.; Oman, L.; Stenchikov, G. L.

2006-11-01

275

Influence of the Flow Rate of Oxidising Atmosphere on the Flame Spread Rate on the Surface of Organic Setlled Dust  

NASA Astrophysics Data System (ADS)

The presented paper deals with determining the influence of the flow rate of oxidising atmosphere on the flame spread along the surface of the organic settled dust layer. We determined the rate of the flame spread on the surface of the organic settled dust layer (whole grain rye and spelt flour) with absolute moisture of 10 % wt., for the flow rates of oxidising atmosphere 1, 3, 5 and 10 cm/s. Pure oxygen was used as an oxidising atmosphere. The obtained results suggest that there exists a power relationship of the flame spread rate along the surface of organic settled dust layer to the flow rate of the oxidising mixture. The method described is suitable for the relative comparison of the organic settled dust layer from the point of its ability to spread the flame and the influence of the air flow rate on this process.

Martinka, Jozef; Balog, Karol; Hrušovský, Ivan; Valentová, Veronika

2013-01-01

276

Increasing Mississippi river discharge throughout the 21st century influenced by changes in climate, land use, and atmospheric CO2  

NASA Astrophysics Data System (ADS)

studies have demonstrated that changes in temperature and precipitation (hereafter climate change) would influence river discharge, but the relative importance of climate change, land use, and elevated atmospheric CO2 have not yet been fully investigated. A process-based projection for the Mississippi River basin suggests that river discharge would be substantially enhanced (10.7-59.8%) by the 2090s compared to the recent decade (2000s), although large discrepancies exist among different climate, atmospheric CO2, and land use change scenarios. Our factorial analyses further indicate that the combined effects of land use change and human-induced atmospheric CO2 elevation on river discharge would outweigh climate change effect under the high-emission scenario (A2) of the Intergovernmental Panel for Climate Change, while climate change would still play the dominant role under the low-emission scenario (B1). This study highlights the important role of anthropogenic factors in influencing future hydrological processes and water resources.

Tao, Bo; Tian, Hanqin; Ren, Wei; Yang, Jia; Yang, Qichun; He, Ruoying; Cai, Weijun; Lohrenz, Steven

2014-07-01

277

Atmospheric transport and outflow of polycyclic aromatic hydrocarbons from China  

Microsoft Academic Search

A potential receptor influence function (PRIF) model, based on air mass forward trajectory calculations, was applied to simulate the atmospheric transport and outflow of polycyclic aromatic hydrocarbons (PAHs) emitted from China. With a 10 day atmospheric transport time, most neighboring countries and regions, as well as remote regions, were influenced by PAH emissions from China. Of the total annual PAH

Chang Lang; Shu Tao; Wenxin Liu; Yanxu Zhang; Staci Simonich

2008-01-01

278

Influences of cosmic radiation, artificial radioactivity and aerosol concentration upon the fair-weather atmospheric electric field in Lisbon (1955–1991)  

Microsoft Academic Search

The atmospheric electric field is influenced by cosmic radiation, radioactivity and aerosols. In this work we investigate the existence of: (i) correlations between relative anomalies of annual values of atmospheric electric field and cosmic radiation intensity, artificial radioactivity and aerosol concentration; (ii) seasonal correlations between relative anomalies of the atmospheric electric field and cosmic radiation intensity. We used data of

Cláudia Serrano; A. Heitor Reis; Rui Rosa; Paulo S. Lucio

2006-01-01

279

Influences of cosmic radiation, artificial radioactivity and aerosol concentration upon the fair-weather atmospheric electric field in Lisbon (1955 1991)  

Microsoft Academic Search

The atmospheric electric field is influenced by cosmic radiation, radioactivity and aerosols. In this work we investigate the existence of: (i) correlations between relative anomalies of annual values of atmospheric electric field and cosmic radiation intensity, artificial radioactivity and aerosol concentration; (ii) seasonal correlations between relative anomalies of the atmospheric electric field and cosmic radiation intensity. We used data of

Cláudia Serrano; A. Heitor Reis; Rui Rosa; Paulo S. Lucio

2006-01-01

280

Impact of Atmospheric Infrared Sounder (AIRS) Thermodynamic Profiles on Regional Weather Forecasting  

NASA Technical Reports Server (NTRS)

In data sparse regions, remotely-sensed observations can be used to improve analyses and lead to better forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), provides temperature and moisture profiles with accuracy comparable to that of radiosondes. The purpose of this paper is to describe a procedure to assimilate AIRS thermodynamic profile data into a regional configuration of the Advanced Research Weather Research and Forecasting (WRF-ARW) model using its three-dimension variational (3DVAR) analysis component (WRF-Var). Quality indicators are used to select only the highest quality temperature and moisture profiles for assimilation in both clear and partly cloudy regions. Separate error characteristics for land and water profiles are also used in the assimilation process. Assimilation results indicate that AIRS profiles produce an analysis closer to in situ observations than the background field. Forecasts from a 37-day case study period in the winter of 2007 show that AIRS profile data can lead to improvements in 6-h cumulative precipitation forecasts due to instability added in the forecast soundings by the AIRS profiles. Additionally, in a convective heavy rainfall event from February 2007, assimilation of AIRS profiles produces a more unstable boundary layer resulting in enhanced updrafts in the model. These updrafts produce a squall line and precipitation totals that more closely reflect ground-based observations than a no AIRS control forecast. The location of available high-quality AIRS profiles ahead of approaching storm systems is found to be of paramount importance to the amount of impact the observations will have on the resulting forecasts.

Chou, Shih-Hung; Zavodsky, Bradley T.; Jedlovee, Gary J.

2010-01-01

281

Influence of ketamine on regional brain glucose use  

SciTech Connect

The purpose of this study was to determine the effect of different doses of ketamine on cerebral function at the level of individual brain structures as reflected by glucose use. Rats received either 5 or 30 mg/kg ketamine intravenously as a loading dose, followed by an infusion to maintain a steady-state level of the drug. An additional group received 30 mg/kg as a single injection only, and was studied 20 min later, by which time they were recovering consciousness (withdrawal group). Regional brain energy metabolism was evaluated with (6-/sup 14/C)glucose and quantitative autoradiography during a 5-min experimental period. A subhypnotic, steady-state dose (5 mg/kg) of ketamine caused a stimulation of glucose use in most brain areas, with an average increase of 20%. At the larger steady-state dose (30 mg/kg, which is sufficient to cause anesthesia), there was no significant effect on most brain regions; some sensory nuclei were depressed (inferior colliculus, -29%; cerebellar dentate nucleus, -18%; vestibular nucleus, -16%), but glucose use in the ventral posterior hippocampus was increased by 33%. In contrast, during withdrawal from a 30-mg/kg bolus, there was a stimulation of glucose use throughout the brain (21-78%), at a time when plasma ketamine levels were similar to the levels in the 5 mg/kg group. At each steady-state dose, as well as during withdrawal, ketamine caused a notable stimulation of glucose use by the hippocampus.

Davis, D.W.; Mans, A.M.; Biebuyck, J.F.; Hawkins, R.A.

1988-08-01

282

Autofluorescence of atmospheric bioaerosols - Biological standard particles and the influence of environmental conditions  

NASA Astrophysics Data System (ADS)

Primary biological aerosol particles (PBAP) such as pollen, fungal spores, bacteria, biogenic polymers and debris from larger organisms are known to influence atmospheric chemistry and physics, the biosphere and public health. PBAP can account for up to ~30% of fine and up to ~70% of coarse particulate matter in urban, rural and pristine environment and are released with estimated emission rates of up to ~1000 Tg/a [1]. Continuous measurements of the abundance, variability and diversity of PBAP have been difficult until recently, however. The application of on-line instruments able to detect autofluorescence from biological particles in real-time has been a promising development for the measurement of PBAP concentrations and fluxes in different environments [2,3]. The detected fluorescent biological aerosol particles (FBAP) can be regarded as a subset of PBAP, although the exact relationship between PBAP and FBAP is still being investigated. Autofluorescence of FBAP is usually a superposition of fluorescence from a mixture of individual fluorescent molecules (fluorophores). Numerous biogenic fluorophores such as amino acids (e.g., tryptophan, tyrosine), coenzymes (e.g., NAD(P)H, riboflavin) and biopolymers (e.g., cellulose) emit fluorescent light due to heterocyclic aromatic rings or conjugated double bonds within their molecular structures. The tryptophan emission peak is a common feature of most bioparticles because the amino acid is a constituent of many proteins and peptides. The influence of the coenzymes NAD(P)H and riboflavin on the autofluorescence of bacteria can be regarded as an indicator for bacterial metabolism and has been utilized to discriminate between viable and non-viable organisms [4]. However, very little information is available about other essential biofluorophores in fungal spores and pollen. In order to better understand the autofluorescence behavior of FBAP, we have used fluorescence spectroscopy and fluorescence microscopy to analyze standard bioparticles (pollen, fungal spores, and bacteria) as well as atmospherically relevant chemical substances. We addressed the sensitivity and selectivity of autofluorescence based online techniques. Moreover, we investigated the influence of environmental conditions, such as relative humidity and oxidizing agents in the atmosphere, on the autofluorescence signature of standard bioparticles. Our results will support the molecular understanding and quantitative interpretation of data obtained by real-time FBAP instrumentation [5,6]. [1] Elbert, W., Taylor, P. E., Andreae, M. O., & Pöschl, U. (2007). Atmos. Chem. Phys., 7, 4569-4588. [2] Huffman, J. A., Treutlein, B., & Pöschl, U. (2010). Atmos. Chem. Phys., 10, 3215-3233. [3] Pöschl, U., et al. (2010). Science, 329, 1513-1516. [4] Lakowicz, J., Principles of fluorescence spectroscopy, Plenum publishers, New York, 1999. [5] Pöhlker, C., Huffman, J. A., & Pöschl, U., (2012). Atmos. Meas. Tech., 5, 37-71. [6] Pöhlker, C., Huffman, J. A., Förster J.-D., & Pöschl, U., (2012) in preparation.

Pöhlker, Christopher; Huffman, J. Alex; Förster, Jan-David; Pöschl, Ulrich

2013-04-01

283

The influence of inter-annually varying albedo on regional climate and drought  

E-print Network

The influence of inter-annually varying albedo on regional climate and drought X. H. Meng · J. P, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate the drought that occurred from 2002 through 2006. Using the observed albedo pro- duced a drier simulation

Evans, Jason

284

An evaluation of a coupled atmosphere-ocean modelling system for regional climate studies: extreme events in the North Atlantic  

NASA Astrophysics Data System (ADS)

We investigate the ability of a coupled regional atmosphere-ocean modelling system to simulate two extreme events in the North Atlantic. In this study we use the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST; Warner et al.) modelling system with only the atmosphere and ocean models activated. COAWST couples the atmosphere model (Weather Research and Forecasting model; WRF) to the ocean model (Regional Ocean Modelling System; ROMS) with the Model Coupling Toolkit. Results from the coupled system are compared with atmosphere only simulations of North Atlantic storms to evaluate the performance of the coupled modelling system. Two extreme events (Hurricane Katia and Hurricane Irene) were chosen to assess the level of improvement (or otherwise) arising from coupling WRF with ROMS. These two hurricanes involve different dynamics and present different challenges to the modeling system. This provides a robust assessment of the advantages or disadvantages of coupling WRF with ROMS for regional climate modelling studies of extreme events in the North Atlantic. We examine the ability of the coupled modelling system to simulate these two extreme events by comparing modelled storm tracks, storm intensities, wind speeds and sea surface temperatures with observations in all cases. The effect of domain size, and two different planetary boundary layers used in WRF are also reported.

Mooney, Priscilla A.; Mulligan, Frank J.

2013-04-01

285

The Atmospheric Radiation Measurement Program May 2003 Intensive Operations Period Examining Aerosol Properties and Radiative Influences: Preface to Special Section  

NASA Technical Reports Server (NTRS)

Atmospheric aerosols influence climate by scattering and absorbing radiation in clear air (direct effects) and by serving as cloud condensation nuclei, modifying the microphysical properties of clouds, influencing radiation and precipitation development (indirect effects). Much of present uncertainty in forcing of climate change is due to uncertainty in the relations between aerosol microphysical and optical properties and their radiative influences (direct effects) and between microphysical properties and their ability to serve as cloud condensation nuclei at given supersaturations (indirect effects). This paper introduces a special section that reports on a field campaign conducted at the Department of Energy Atmospheric Radiation Measurement site in North Central Oklahoma in May, 2003, examining these relations using in situ airborne measurements and surface-, airborne-, and space-based remote sensing.

Ferrare, Richard; Feingold, Graham; Ghan, Steven; Ogren, John; Schmid, Beat; Schwartz, Stephen E.; Sheridan, Pat

2006-01-01

286

Surfactants in the sea-surface microlayer and atmospheric aerosol around the southern region of Peninsular Malaysia.  

PubMed

This study was conducted to determine the composition of surfactants in the sea-surface microlayer (SML) and atmospheric aerosol around the southern region of the Peninsular Malaysia. Surfactants in samples taken from the SML and atmospheric aerosol were determined using a colorimetric method, as either methylene blue active substances (MBAS) or disulphine blue active substances (DBAS). Principal component analysis with multiple linear regressions (PCA-MLR), using the anion and major element composition of the aerosol samples, was used to determine possible sources of surfactants in atmospheric aerosol. The results showed that the concentrations of surfactants in the SML and atmospheric aerosol were dominated by anionic surfactants and that surfactants in aerosol were not directly correlated (p>0.05) with surfactants in the SML. Further PCA-MLR from anion and major element concentrations showed that combustion of fossil fuel and sea spray were the major contributors to surfactants in aerosol in the study area. PMID:24930738

Jaafar, Shoffian Amin; Latif, Mohd Talib; Chian, Chong Woan; Han, Wong Sook; Wahid, Nurul Bahiyah Abd; Razak, Intan Suraya; Khan, Md Firoz; Tahir, Norhayati Mohd

2014-07-15

287

Influences of the 2010 Eyjafjallajökull volcanic plume on air quality in the northern Alpine region  

NASA Astrophysics Data System (ADS)

A series of major eruptions of the Eyjafjallajökull volcano in Iceland started on 14 April 2010 and continued until the end of May 2010. The volcanic emissions moved over nearly the whole of Europe and were observed first on 16 April 2010 in Southern Germany with different remote sensing systems from the ground and space. Enhanced PM10 and SO2 concentrations were detected on 17 April at mountain stations (Zugspitze/Schneefernerhaus and Schauinsland) as well as in Innsbruck by in situ measurement devices. On 19 April intensive vertical mixing and advection along with clear-sky conditions facilitated the entrainment of volcanic material down to the ground. The subsequent formation of a stably stratified lower atmosphere with limited mixing near the ground during the evening of 19 April led to an additional enhancement of near-surface particle concentrations. Consequently, on 19 April and 20 April exceedances of the daily threshold value for particulate matter (PM10) were reported at nearly all monitoring stations of the North Alpine foothills as well as at mountain and valley stations in the northern Alps. The chemical analyses of ambient PM10 at monitoring stations of the North Alpine foothills yielded elevated Titanium concentrations on 19/20 April which prove the presence of volcanic plume material. Following this result the PM10 threshold exceedances are also associated with the volcanic plume. The entrainment of the volcanic plume material mainly affected the concentrations of coarse particles (>1 ?m) - interpreted as volcanic ash - and ultrafine particles (<100 nm), while the concentrations of accumulation mode aerosol (0.1-1 ?m) were not changed significantly. With regard to the occurrence of ultrafine particles, it is concluded that their formation was triggered by high sulphuric acid concentrations which are necessarily generated by the photochemical processes in a plume rich in sulphur dioxide under high solar irradiance. It became evident that during the course of several days, the Eyjafjallajökull volcanic emissions influenced the near-surface atmosphere and thus the ambient air quality. Although the volcanic plume contributed to the overall exposure of the population of the northern Alpine region on two days, only minor effects on the exacerbation of respiratory and cardiovascular symptoms can be expected.

Schäfer, K.; Thomas, W.; Peters, A.; Ries, L.; Obleitner, F.; Schnelle-Kreis, J.; Birmili, W.; Diemer, J.; Fricke, W.; Junkermann, W.; Pitz, M.; Emeis, S.; Forkel, R.; Suppan, P.; Flentje, H.; Gilge, S.; Wichmann, H. E.; Meinhardt, F.; Zimmermann, R.; Weinhold, K.; Soentgen, J.; Münkel, C.; Freuer, C.; Cyrys, J.

2011-08-01

288

New evidence of the influence of the interplanetary magnetic field on middle-latitude surface atmospheric pressure  

NASA Astrophysics Data System (ADS)

For the polar regions, results have been published over several decades that indicate a meteorological response to the east-west component of the interplanetary magnetic field (IMF), By. Here we present evidence of a previously unrecognised influence of IMF on mid-latitude surface pressure. We examine the difference, ?p(By), between the mean surface pressure for high and low values of IMF By (e.g., By > 3nT and By < -3nT) using NCEP/NCAR reanalysis data in a 50 year interval (1963-2012) for the whole surface of the Earth at a resolution of 2.5 deg. in latitude and longitude. Similarly we find the difference, ?p(Bz), between the mean surface pressures for high and low values of the north-south component of the IMF, Bz. The Student t-test is used to assess the statistical significance of the results. Both ?p(By) and ?p(Bz) possess a significant mid-latitude wave structure. This structure circles the Earth with a wave number of about 4-5, and is similar in location and structure to the cyclones and anti-cyclones produced by the action of atmospheric Rossby waves on the jet stream. Our results indicate that the mechanism that produces atmospheric responses to IMF in the polar regions is also able to modulate pre-existing weather patterns at mid-latitudes. Our results also confirm those published by Burns et al. in 2008 (J. Geophys. Res. 113 - hereafter B08) who found a statistically-significant dependence of surface pressure variations on IMF By at Antarctic stations for 1995-2005, and at Arctic stations for 1999-2002 (around solar maximum). We extend this work to test whether ?p(By) is consistently positive in the Antarctic and negative in the Arctic over the interval 1963-2012. Lastly, we find a significant correlation of surface pressure with IMF Bz at middle to high latitudes, in contrast to a previous study in J. Geophys. Res. 112, in 2007, by Burns et al. (B07). This may be reconciled by recognising that the amplitude of ?p(Bz) is spatially dependent and that the largest values may not be expected to occur at Vostok, where the results of B07 were obtained. It has been proposed that the observed effect of IMF on the atmosphere occurs as a result of modulation of the current density of the atmospheric circuit via the interplanetary electric field, with subsequent changes in cloud dynamics. An investigation of the effect of (i) a time lag between the IMF and the surface pressure and of (ii) the spatial variation of ?p(By) and ?p(Bz) will be used to consider possible mechanisms that can account for our results.

Lam, M.; Chisham, G.; Freeman, M. P.

2012-12-01

289

The importance of source configuration in quantifying footprints of regional atmospheric sulphur deposition.  

PubMed

An atmospheric transport-chemistry model is applied to investigate the effects of source configuration in simulating regional sulphur deposition footprints from elevated point sources. Dry and wet depositions of sulphur are calculated for each of the 69 largest point sources in the UK. Deposition contributions for each point source are calculated for 2003, as well as for a 2010 emissions scenario. The 2010 emissions scenario has been chosen to simulate the Gothenburg protocol emission scenario. Point source location is found to be a major driver of the dry/wet deposition ratio for each deposition footprint, with increased precipitation scavenging of SO(x) in hill areas resulting in a larger fraction of the emitted sulphur being deposited within the UK for sources located near these areas. This reduces exported transboundary pollution, but, associated with the occurrence of sensitive soils in hill areas, increases the domestic threat of soil acidification. The simulation of plume rise using individual stack parameters for each point source demonstrates a high sensitivity of SO(2) surface concentration to effective source height. This emphasises the importance of using site-specific information for each major stack, which is rarely included in regional atmospheric pollution models, due to the difficulty in obtaining the required input data. The simulations quantify how the fraction of emitted SO(x) exported from the UK increases with source magnitude, effective source height and easterly location. The modelled reduction in SO(x) emissions, between 2003 and 2010 resulted in a smaller fraction being exported, with the result that the reductions in SO(x) deposition to the UK are less than proportionate to the emission reduction. This non-linearity is associated with a relatively larger fraction of the SO(2) being converted to sulphate aerosol for the 2010 scenario, in the presence of ammonia. The effect results in less-than-proportional UK benefits of reducing in SO(2) emissions, together with greater-than-proportional benefits in reducing export of UK SO(2) emissions. PMID:19903570

Vieno, M; Dore, A J; Bealey, W J; Stevenson, D S; Sutton, M A

2010-01-15

290

Influence of aerosol chemical composition on N2O5 uptake: airborne regional measurements in northwestern Europe  

NASA Astrophysics Data System (ADS)

Aerosol chemical composition was found to influence nighttime atmospheric chemistry during a series of airborne measurements in northwestern Europe in summer conditions, which has implications for regional air quality and climate. The uptake of dinitrogen pentoxide, ? (N2O5), to particle surfaces was found to be modulated by the amount of water content and ammonium nitrate present in the aerosol. The conditions prevalent in this study suggest that the net uptake rate of N2O5 to atmospheric aerosols was relatively efficient compared to previous studies, with ? (N2O5) values in the range 0.01-0.03. This is likely a consequence of the elevated relative humidity in the region, which promotes greater aerosol water content. Increased nitrate concentrations relative to particulate water were found to suppress N2O5 uptake. The results presented here contrast with previous ambient studies of N2O5 uptake, which have generally taken place in low-nitrate environments in the USA. Comparison of the N2O5 uptake derived from the measurements with a parameterised scheme that is based on the ratio of particulate water to nitrate yielded reasonably good agreement in terms of the magnitude and variation in uptake, provided the effect of chloride was neglected. An additional suppression of the parameterised uptake is likely required to fully capture the variation in N2O5 uptake, which could be achieved via the known suppression by organic aerosol. However, existing parameterisations representing the suppression by organic aerosol were unable to fully represent the variation in N2O5 uptake. These results provide important ambient measurement constraint on our ability to predict N2O5 uptake in regional and global aerosol models. N2O5 uptake is a potentially important source of nitrate aerosol and a sink of the nitrate radical, which is the main nocturnal oxidant in the atmosphere. The results further highlight the importance of ammonium nitrate in northwestern Europe as a key component of atmospheric composition in the region.

Morgan, W. T.; Ouyang, B.; Allan, J. D.; Aruffo, E.; Di Carlo, P.; Kennedy, O. J.; Lowe, D.; Flynn, M. J.; Rosenberg, P. D.; Williams, P. I.; Jones, R.; McFiggans, G. B.; Coe, H.

2015-01-01

291

Influence of aerosol chemical composition on N2O5 uptake: airborne regional measurements in North-Western Europe  

NASA Astrophysics Data System (ADS)

Aerosol chemical composition was found to influence nighttime atmospheric chemistry during a series of airborne measurements in North-Western Europe in summer conditions, which has implications for regional air quality and climate. The uptake of dinitrogen pentoxide, ? (N2O5), to particle surfaces was found to be modulated by the amount of water content and ammonium nitrate present in the aerosol. The conditions prevalent in this study suggest that the net uptake rate of N2O5 to atmospheric aerosols was relatively efficient compared to previous studies, with ? (N2O5) values in the range 0.01-0.03. This is likely a consequence of the elevated relative humidity in the region, which promotes greater aerosol water content. Increased nitrate concentrations relative to particulate water were found to suppress N2O5 uptake. The results presented here contrast with previous ambient studies of N2O5 uptake, which have generally taken place in low-nitrate environments in the USA. Comparison of the N2O5 uptake derived from the measurements with a parameterised scheme that is based on the ratio of particulate water to nitrate yielded reasonably good agreement in terms of the magnitude and variation in uptake, provided the effect of chloride was neglected. An additional suppression of the parameterised uptake is likely required to fully capture the variation in N2O5 uptake, which could be achieved via the known suppression by organic aerosol. However, existing parameterisations representing the suppression by organic aerosol were unable to fully represent the variation in N2O5 uptake. These results provide important ambient measurement constraint on our ability to predict N2O5 uptake in regional and global aerosol models. N2O5 uptake is a potentially important source of nitrate aerosol and a sink of the nitrate radical, which is the main nocturnal oxidant in the atmosphere. The results further highlight the importance of ammonium nitrate in North-Western Europe as a key component of atmospheric composition in the region.

Morgan, W. T.; Ouyang, B.; Allan, J. D.; Aruffo, E.; Di Carlo, P.; Kennedy, O. J.; Lowe, D.; Flynn, M. J.; Rosenberg, P. D.; Williams, P. I.; Jones, R.; McFiggans, G. B.; Coe, H.

2014-07-01

292

The Influence of the Interplanetary Magnetic Field (IMF) on Atmospheric Escape at Mars  

NASA Astrophysics Data System (ADS)

We present a study on the response of Mars’ atmosphere to changes in the interplanetary magnetic field (IMF) configuration, specifically with respect to the atmospheric escape rate via pick up ions and upcoming MAVEN observations.

Curry, S. M.; Luhmann, J. G.; Ma, Y.; Dong, C. F.; Brain, D. A.

2014-07-01

293

Absorption coefficient of HCl in the region 1400 to 2200 A. [for photodissociation rate in Venus atmosphere  

NASA Technical Reports Server (NTRS)

The results of absorption coefficient measurements of HCl in the region 1400 to 2200 A are reported and compared with those previously published. It is concluded that the present results represent the best compromise of all measurements and should be used for any calculations on the photodissociation rate of HCl in planetary atmospheres.

Inn, E. C. Y.

1975-01-01

294

Atmospheric inverse modeling to constrain regional-scale CO2 budgets at high spatial and temporal resolution  

Microsoft Academic Search

We present an inverse modeling framework designed to constrain CO2 budgets at regional scales. The approach captures atmospheric transport processes in high spatiotemporal resolution by coupling a mesoscale model with Lagrangian Stochastic backward trajectories. Terrestrial biosphere CO2 emissions are generated through a simple diagnostic flux model that splits the net ecosystem exchange into its major components of gross primary productivity

Mathias Göckede; Anna M. Michalak; Dean Vickers; David P. Turner; Beverly E. Law

2010-01-01

295

New Developments in the Regional Atmospheric Modeling System Suitable for Simulations of Snowpack Augmentation over Complex Terrain  

Microsoft Academic Search

The Colorado State University Regional Atmospheric Modeling System (RAMS) has been used to emulate cloud seeding operations in the Colorado Rocky Mountains for the winter of 2003-2004 in a previous study (Cotton et al. 2006). This paper documents new developments in RAMS since that study using a winter storm simulation that occurred in Colorado from 3-4 November 2003 as an

Stephen M. Saleeby; William Y. Y. Cheng; William R. Cotton

2007-01-01

296

Neutral Atmospheric Influences of the Solar Proton Events in October-November 2003  

NASA Technical Reports Server (NTRS)

The large solar storms in October-November 2003 caused solar proton events (SPEs) at the Earth and impacted the middle atmospheric polar cap regions. Although occurring near the end of the maximum of solar cycle 23, the fourth largest period of SPES measured in the past 40 years happened 28-31 October 2003. The highly energetic protons associated with the SPEs produced ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which led to the production of odd hydrogen (HO(sub x)) and odd nitrogen (NO(sub y)). NO(sub x) (NO + NO2) was observed by the UARS HALOE instrument to increase over 20 ppbv throughout the Southern Hemisphere polar lower mesosphere. The NOAA 16 SBUV/2 instrument measured a short-term ozone depletion of 40% in the Southern Hemisphere polar lower mesosphere, probably a result of the HO(sub x) increases. SBUV/2 observations showed ozone depletions of 5-8% in the southern polar upper stratosphere lasting days beyond the events, most likely a result of the NO(sub y) enhancements. Longer-term Northern Hemisphere polar total ozone decreases of >0.5% were predicted to last for over 8 months past the events with the Goddard Space Flight Center two-dimensional model. Although the production of NO(sub y) constituents is the same in both hemispheres, the NO(sub y) constituents have a much larger impact in the northern than the southern polar latitudes because of the seasonal differences between the two hemispheres. These observations and model computations illustrate the substantial impact of solar protons on the polar neutral middle atmosphere.

Jackman, Charles H.; DeLand, Matthew T.; Labow, Gordon J.; Fleming, Eric L.; Weisenstein, Debra K.; Ko, Malcolm K. W.; Sinnhuber, Miriam; Russell, James M.

2005-01-01

297

The influence of plants on atmospheric methane in an agriculture-dominated landscape  

NASA Astrophysics Data System (ADS)

The primary objective of this study was to clarify the influence of crop plants on atmospheric methane (CH4) in an agriculture-dominated landscape in the Upper Midwest of the United States. Measurements were carried out at two contrasting scales. At the plant scale, CH4 fluxes from soybean and corn plants were measured with a laser-based plant chamber system. At the landscape scale, the land surface flux was estimated with a modified Bowen ratio technique using measurements made on a tall tower. The chamber data revealed a diurnal pattern for the plant CH4 flux: it was positive (an emission rate of 0.4 ± 0.1 nmol m-2 s-1, average of soybean and corn, in reference to the unit ground area) during the day, and negative (an uptake rate of -0.8 ± 0.8 nmol m-2 s-1) during the night. At the landscape scale, the flux was estimated to be 14.8 nmol m-2 s-1 at night and highly uncertain during the day, but the available references and the flux estimates from the equilibrium methods suggested that the CH4 flux during the entire observation period was similar to the estimated nighttime flux. Thus, soybean and corn plants have a negligible role in the landscape-scale CH4 budget.

Zhang, Xin; Lee, Xuhui; Griffis, Timothy J.; Baker, John M.; Erickson, Matt D.; Hu, Ning; Xiao, Wei

2014-07-01

298

Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure  

E-print Network

at atmospheric pressure A. Sáinz1 , J. Margot2 , M. C. García1 , M. D. Calzada1 1 Grupo de Espectroscopía de+ ) are also expected to play an important role in the discharge kinetics. At atmospheric pressure obeys the Saha-Boltzmann distribution. However, at atmospheric pressure, molecular recombination

Boyer, Edmond

299

Local and regional factors affecting atmospheric mercury speciation at a remote location  

USGS Publications Warehouse

Atmospheric concentrations of elemental (Hg0), reactive gaseous (RGM), and particulate (PHg) mercury were measured at two remote sites in the midwestern United States. Concurrent measurements of Hg0, PHg, and RGM obtained at Devil's Lake and Mt. Horeb, located approximately 65 km apart, showed that Hg0 and PHg concentrations were affected by regional, as well as local sources, while RGM was mainly impacted by local sources. Plumes reaching the Devil's Lake site from a nearby coal-fired power plant significantly impacted SO2 and RGM concentrations at Devil's Lake, but had little impact on Hg0. Our findings suggest that traditional modeling approaches to assess sources of mercury deposited that utilize source emissions and large-scale grids may not be sufficient to predict mercury deposition at sensitive locations due to the importance of small-scale sources and processes. We suggest the use of a receptor-based monitoring to better understand mercury source-receptor relationships. ?? 2007 NRC Canada.

Manolopoulos, H.; Schauer, J.J.; Purcell, M.D.; Rudolph, T.M.; Olson, M.L.; Rodger, B.; Krabbenhoft, D.P.

2007-01-01

300

Preliminary evaluation of a regional atmospheric chemical data assimilation system for environmental surveillance.  

PubMed

We report the progress of an ongoing effort by the Air Resources Laboratory, NOAA to build a prototype regional Chemical Analysis System (ARLCAS). The ARLCAS focuses on providing long-term analysis of the three dimensional (3D) air-pollutant concentration fields over the continental U.S. It leverages expertise from the NASA Earth Science Division-sponsored Air Quality Applied Science Team (AQAST) for the state-of-science knowledge in atmospheric and data assimilation sciences. The ARLCAS complies with national operational center requirement protocols and aims to have the modeling system to be maintained by a national center. Meteorology and chemistry observations consist of land-, air- and space-based observed and quality-assured data. We develop modularized testing to investigate the efficacies of the various components of the ARLCAS. The sensitivity testing of data assimilation schemes showed that with the increment of additional observational data sets, the accuracy of the analysis chemical fields also increased incrementally in varying margins. The benefit is especially noted for additional data sets based on a different platform and/or a different retrieval algorithm. We also described a plan to apply the analysis chemical fields in environmental surveillance at the Centers for Disease Control and Prevention. PMID:25514141

Lee, Pius; Liu, Yang

2014-01-01

301

Preliminary evaluation of a regional atmospheric chemical data assimilation system for environmental surveillance.  

PubMed

We report the progress of an ongoing effort by the Air Resources Laboratory,NOAA to build a prototype regional Chemical Analysis System (ARLCAS). The ARLCAS focuses on providing long-term analysis of the three dimensional (3D) air-pollutant concentration fields over the continental U.S. It leverages expertise from the NASA Earth Science Division-sponsored Air Quality Applied Science Team (AQAST) for the state-of-science knowledge in atmospheric and data assimilation sciences. The ARLCAS complies with national operational center requirement protocols and aims to have the modeling system to be maintained by a national center. Meteorology and chemistry observations consist of land-, air- and space-based observed and quality-assured data.We develop modularized testing to investigate the efficacies of the various components of the ARLCAS. The sensitivity testing of data assimilation schemes showed that with the increment of additional observational data sets, the accuracy of the analysis chemical fields also increased incrementally in varying margins. The benefit is especially noted for additional data sets based on a different platform and/or a different retrieval algorithm.We also described a plan to apply the analysis chemical fields in environmental surveillance at the Centers for Disease Control and Prevention. PMID:25587606

Lee, Pius; Liu, Yang

2014-12-01

302

Springtime atmospheric mercury speciation in the McMurdo, Antarctica coastal region  

NASA Astrophysics Data System (ADS)

This paper describes springtime atmospheric mercury (Hg) speciation and snow pack mercury concentration measurements in the McMurdo/Ross Island sea ice region of Antarctica. Near-surface gaseous elemental mercury (GEM) depletions (to concentrations below our detection limit, <0.01 ng m -3), similar to those shown to occur in the springtime Arctic, were observed and reactive gaseous mercury (RGM) and fine particulate mercury (FPM) were produced in significant quantities (average 116 and 49 pg(Hg) m -3, respectively). GEM concentrations in the near-surface air were significantly enhanced during brief afternoon terrestrial snowmelt events. Snow pack total mercury was significantly elevated (40-430 ng l -1), with a maximum at the northern extent of the fast-ice (adjacent to the grease ice/freezing ocean surface), and lesser values towards the coast and on Ross Island, suggesting that, similarly again to recent Arctic results, marine halogens, released by the freezing sea surface, induce localized mercury depletion events. A possible secondary contributing source of local halogens and mercury are direct emissions from the active Ross Island volcano, Mt. Erebus.

Brooks, Steven; Lindberg, Steven; Southworth, George; Arimoto, Richard

303

Preliminary Evaluation of a Regional Atmospheric Chemical Data Assimilation System for Environmental Surveillance  

PubMed Central

We report the progress of an ongoing effort by the Air Resources Laboratory, NOAA to build a prototype regional Chemical Analysis System (ARLCAS). The ARLCAS focuses on providing long-term analysis of the three dimensional (3D) air-pollutant concentration fields over the continental U.S. It leverages expertise from the NASA Earth Science Division-sponsored Air Quality Applied Science Team (AQAST) for the state-of-science knowledge in atmospheric and data assimilation sciences. The ARLCAS complies with national operational center requirement protocols and aims to have the modeling system to be maintained by a national center. Meteorology and chemistry observations consist of land-, air- and space-based observed and quality-assured data. We develop modularized testing to investigate the efficacies of the various components of the ARLCAS. The sensitivity testing of data assimilation schemes showed that with the increment of additional observational data sets, the accuracy of the analysis chemical fields also increased incrementally in varying margins. The benefit is especially noted for additional data sets based on a different platform and/or a different retrieval algorithm. We also described a plan to apply the analysis chemical fields in environmental surveillance at the Centers for Disease Control and Prevention. PMID:25514141

Lee, Pius; Liu, Yang

2014-01-01

304

The Evaluation of the Regional Atmospheric Modeling System in the Eastern Range Dispersion Assessment System  

NASA Technical Reports Server (NTRS)

The Applied Meteorology Unit (AMU) evaluated the Regional Atmospheric Modeling System (RAMS) contained within the Eastern Range Dispersion Assessment System (ERDAS). ERDAS provides emergency response guidance for Cape Canaveral Air Force Station and Kennedy Space Center operations in the event of an accidental hazardous material release or aborted vehicle launch. The RAMS prognostic data are available to ERDAS for display and are used to initialize the 45th Space Wing/Range Safety dispersion model. Thus, the accuracy of the dispersion predictions is dependent upon the accuracy of RAMS forecasts. The RAMS evaluation consisted of an objective and subjective component for the 1999 and 2000 Florida warm seasons, and the 1999-2000 cool season. In the objective evaluation, the AMU generated model error statistics at surface and upper-level observational sites, compared RAMS errors to a coarser RAMS grid configuration, and benchmarked RAMS against the nationally-used Eta model. In the subjective evaluation, the AMU compared forecast cold fronts, low-level temperature inversions, and precipitation to observations during the 1999-2000 cool season, verified the development of the RAMS forecast east coast sea breeze during both warm seasons, and examined the RAMS daily thunderstorm initiation and precipitation patterns during the 2000 warm season. This report summarizes the objective and subjective verification for all three seasons.

Case, Jonathan

2001-01-01

305

Evaluation of the Regional Atmospheric Modeling System in the Eastern Range Dispersion Assessment System  

NASA Technical Reports Server (NTRS)

The Applied Meteorology Unit is conducting an evaluation of the Regional Atmospheric Modeling System (RAMS) contained within the Eastern Range Dispersion Assessment System (ERDAS). ERDAS provides emergency response guidance for operations at the Cape Canaveral Air Force Station and the Kennedy Space Center in the event of an accidental hazardous material release or aborted vehicle launch. The prognostic data from RAMS is available to ERDAS for display and is used to initialize the 45th Range Safety (45 SW/SE) dispersion model. Thus, the accuracy of the 45 SW/SE dispersion model is dependent upon the accuracy of RAMS forecasts. The RAMS evaluation task consists of an objective and subjective component for the Florida warm and cool seasons of 1999-2000. The objective evaluation includes gridded and point error statistics at surface and upper-level observational sites, a comparison of the model errors to a coarser grid configuration of RAMS, and a benchmark of RAMS against the widely accepted Eta model. The warm-season subjective evaluation involves a verification of the onset and movement of the Florida east coast sea breeze and RAMS forecast precipitation. This interim report provides a summary of the RAMS objective and subjective evaluation for the 1999 Florida warm season only.

Case, Jonathan

2000-01-01

306

Regional variations in the influence of mesoscale eddies on near-surface chlorophyll  

NASA Astrophysics Data System (ADS)

can influence biogeochemical cycles through a variety of mechanisms, including the excitation of vertical velocities and the horizontal advection of nutrients and ecosystems, both around the eddy periphery by rotational currents and by the trapping of fluid and subsequent transport by the eddy. In this study, we present an analysis of the influence of mesoscale ocean eddies on near-surface chlorophyll (CHL) estimated from satellite measurements of ocean color. The influences of horizontal advection, trapping, and upwelling/downwelling on CHL are analyzed in an eddy-centric frame of reference by collocating satellite observations to eddy interiors, as defined by their sea surface height signatures. The influence of mesoscale eddies on CHL varies regionally. In most boundary current regions, cyclonic eddies exhibit positive CHL anomalies and anticyclonic eddies contain negative CHL anomalies. In the interior of the South Indian Ocean, however, the opposite occurs. The various mechanisms by which eddies can influence phytoplankton communities are summarized and regions where the observed CHL response to eddies is consistent with one or more of the mechanisms are discussed. This study does not attempt to link the observed regional variability definitively to any particular mechanism but provides a global overview of how eddies influence CHL anomalies.

Gaube, Peter; McGillicuddy, Dennis J.; Chelton, Dudley B.; Behrenfeld, Michael J.; Strutton, Peter G.

2014-12-01

307

Individual and coupled influences of AMO and ENSO on regional precipitation characteristics and extremes  

NASA Astrophysics Data System (ADS)

the influences of Atlantic multidecadal oscillation (AMO) and El Niño southern oscillation (ENSO) on regional precipitation extremes and characteristics in the state of Florida is the focus of this study. Exhaustive evaluations of individual and combined influences of these oscillations using, descriptive indices-based assessment of statistically significant changes in rainfall characteristics, identification of spatially varying influences of oscillations on dry and wet spell transition states, antecedent precipitation prior to extreme events, intraevent temporal distribution of precipitation and changes in temporal occurrences of extremes including dry/wet cycles are carried out. Rain gage and gridded precipitation data analysis using parametric hypothesis tests confirm statistically significant changes in the precipitation characteristics from one phase to another of each oscillation and also in coupled phases. Spatially nonuniform and uniform influences of AMO and ENSO, respectively, on precipitation are evident. AMO influences vary in peninsular and continental parts of Florida and the warm (cool) phase of AMO contributes to increased precipitation extremes during wet (dry) season. The influence of ENSO is confined to dry season with El Niño (La Niña) contributing to increase (decrease) in extremes and total precipitation. Wetter antecedent conditions preceding daily extremes are dominant in AMO warm phase compared to the cool and are likely to impact design floods in the region. AMO influence on dry season precipitation extremes is noted for ENSO neutral years. The two oscillations in different phases modulate each other with seasonal and spatially varying impacts and implications on flood control and water supply in the region.

Goly, Aneesh; Teegavarapu, Ramesh S. V.

2014-06-01

308

Regional Climate Simulations with COSMO-CLM for West Africa using three different soil-vegetation-atmosphere-transfer (SVAT) module  

NASA Astrophysics Data System (ADS)

Climate predictions on decadal timescales constitute a new field of research, closing the gap between short-term and seasonal weather predictions and long-term climate projections. Therefore, the Federal Ministry of Education and Research in Germany (BMBF) has recently funded the research program MiKlip (Mittelfristige Klimaprognosen), which aims to create a model system that can provide reliable decadal climate forecasts. Recent studies have suggested that one region with high potential decadal predictability is West Africa. Therefore, the project DEPARTURE (DEcadal Prediction of African Rainfall and ATlantic HURricanE Activity) was established within the MiKlip program to assess the feasibility and the potential added value of regional decadal climate predictions for West Africa. To quantify the potential decadal climate predictability, a multi-model approach with the three different regional climate models REMO, WRF and COSMO-CLM (CCLM) will be realized. The presented research will contribute to DEPARTURE by performing hindcast ensemble simulations with CCLM, driven by global decadal MPI-ESM-LR simulations. Thereby, one focus is on the dynamic soil-vegetation-climate interaction on decadal timescales. Recent studies indicate that there are significant feedbacks between the land-surface and the atmosphere, which might influence the decadal climate variability substantially. To investigate this connection, two different SVATs (Community Land Model (CLM), and VEG3D) will be coupled with the CCLM, replacing TERRA_ML, the standard SVAT implemented in CCLM. Thus, sensitive model parameters shall be identified, whereby the understanding of important processes might be improved. As a first step, TERRA_ML is substituted by VEG3D, a SVAT developed at the IMK-TRO, Karlsruhe, Germany. Compared to TERRA_ML, VEG3D includes an explicit vegetation layer by using a big leaf approach, inducing higher correlations with observations as it has been shown in previous studies. The coupling of VEG3D with CCLM is performed by using the OASIS3-MCT coupling software, developed by CERFACS, Toulouse, France. Results of CCLM simulations using both SVATs are analysed and compared for the DEPARTURE model domain. Thereby ERA-Interim driven CCLM simulations with VEG3D showed better agreement with observational data than simulations with TERRA_ML, especially for dense vegetaded areas. This will be demonstrated exemplarily. Additionally, results for MPI-ESM-LR driven decadal hindcast simulations (1966 - 1975) are analysed and presented.

Breil, Marcus; Panitz, Hans-Jürgen

2014-05-01

309

Long-term global sea surface temperature fluctuations and their possible influence on atmospheric CO 2 concentrations  

Microsoft Academic Search

Changes of atmospheric CO2 concentration since 1958 are shown to be related to sea surface temperature changes. The largest contribution to changes arises from the Pacific equatorial upwelling region, with the Indian Ocean and Atlantic contributing only small fractions to the variance. It is hypothesized that the observed relationship is related to the nutrients that are brought up by upwelling

Reginald E. Newell; Alfredo R. Navato; Jane Hsiung

1978-01-01

310

The Effect of Atmosphere-Ocean-Wave Interactions and Model Resolution on Hurricane Katrina in a Coupled Regional Climate Model  

NASA Astrophysics Data System (ADS)

The sensitivity of simulated strength, track, and structure of Hurricane Katrina to atmospheric model resolution, cumulus parameterization, and initialization time, as well as mesoscale ocean-atmosphere interactions with and without small-scale ocean-wave effect, are investigated with a fully coupled regional climate model. The atmosphere, ocean, and wave components are represented by the Weather Research and Forecasting Model (WRF), Regional Ocean Modeling System (ROMS), and Simulating WAves Nearshore (SWAN) model. Uncoupled atmosphere-only simulations with horizontal resolutions of 1, 3, 9, and 27 km show that while the simulated cyclone track is highly sensitive to initialization time, its dependence on model resolution is relatively weak. Using NCEP/CFSR reanalysis as initial and boundary conditions, WRF, even at low resolution, is able to track Katrina accurately for 3 days before it made landfall on August 29, 2005. Katrina's strength, however, is much more difficult to reproduce and exhibits a strong dependence on model resolution. At its lowest resolution (27 km), WRF is only capable of simulating a maximum strength of Category 2 storm. Even at 1 km resolution, the simulated Katrina only reaches Category 4 storm intensity. Further WRF experiments with and without cumulus parameterization reveal minor changes in strength. None of the WRF-only simulations capture the observed rapid intensification of Katrina to Category 5 when it passed over a warm Loop-Current eddy (LCE) in the Gulf of Mexico, suggesting that mesoscale ocean-atmosphere interactions involving LCEs may play a crucial role in Katrina's rapid intensification. Coupled atmosphere-ocean simulations are designed and carried out to investigate hurricane Katrina-LCE interactions with and without considering small-scale ocean wave processes in order to fully understand the dynamical ocean-atmosphere processes in the observed rapid cyclone intensification.

Patricola, C. M.; Chang, P.; Saravanan, R.; Montuoro, R.

2012-04-01

311

Influence of ocean-atmospheric oscillations on lake ice phenology in eastern North America  

NASA Astrophysics Data System (ADS)

Our results reveal long-term trends in ice out dates (1836-2013) for twelve lakes in Maine, New Brunswick and New Hampshire, in eastern North America. The trends are remarkably coherent between lakes (rs = 0.462-0.933, p < 0.01) and correlate closely with the March-April (MA) instrumental temperature records from the region (rs = 0.488-0.816, p < 0.01). This correlation permits use of ice out dates as a proxy to extend the shorter MA instrumental record (1876-2013). Mean ice out dates trended progressively earlier during the recovery from the Little Ice Age through to the 1940s, and gradually became later again through to the late 1970s, when ice out dates had returned to values more typical of the late nineteenth century. Post-1970's ice out dates resumed trending toward earlier dates, with the twenty-first century being characterized by the earliest ice out dates on record. Spectral and wavelet time series analysis indicate that ice out is influenced by several teleconnections including the Quasi-biennial Oscillation, El Niño-Southern Oscillation, North Atlantic Oscillation, as well as a significant correlation between inland lake records and the Atlantic Multidecadal Oscillation. The relative influence of these teleconnections is variable with notable shifts occurring after ~1870, ~1925, and ~1980-2000. The intermittent expression of these cycles in the ice out and MA instrumental record is not only influenced by absolute changes in the intensity of the various teleconnections and other climate drivers, but through phase interference between teleconnections, which periodically damps the various signals.

Timothy, Patterson R.; Swindles, Graeme T.

2014-11-01

312

Resonant conversion of standing acoustic oscillations into Alfv{é}n waves in the $?~ 1$ region of the solar atmosphere  

E-print Network

We show that 5-minute acoustic oscillations may resonantly convert into Alfv{\\'e}n waves in the $\\beta{\\sim}1$ region of the solar atmosphere. Considering the 5-minute oscillations as pumping standing acoustic waves oscillating along unperturbed vertical magnetic field, we find on solving the ideal MHD equations that amplitudes of Alfv{\\'e}n waves with twice the period and wavelength of acoustic waves exponentially grow in time when the sound and Alfv{\\'e}n speeds are equal, i.e. $c_s \\approx v_A$. The region of the solar atmosphere where this equality takes place we call a {\\it swing layer}. The amplified Alfv{\\'e}n waves may easily pass through the chromosphere and transition region carrying the energy of p-modes into the corona.

D. Kuridze; T. V. Zaqarashvili; B. Roberts

2005-10-14

313

Northern Hemisphere Atmospheric Influence of the Solar Proton Events and Ground Level Enhancement in January 2005  

NASA Technical Reports Server (NTRS)

Solar eruptions in early 2005 led substantial barrage of charged particles on the Earth's atmosphere during the January 16-21 period. Proton fluxes were greatly increased during these several days and led to the production ofHO(x)(H, OH, BO2)and NO(x)(N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HO(x) and NO(x) constituents, and associated ozone reductions, due 10 these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH throughout the mesosphere in the 60-82.5degN latitude band due to the SPEs for most days in the Jan.16-2l,2005 period, in reasonable agreement with the Aura Microwave Limb Sounder (MLS) measurements. Mesospheric HO2 is also predicted to be increased by the SPEs, however, the modeled HO2 results are somewhat larger than the MLS measurements. These HO(x) enhancements led to huge predicted and MLS-measured ozone decreases of greater than 40% throughout most of the Northern polar mesosphere during the SPE period. Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measurements of hydrogen peroxide (H2O2) show increases throughout the stratosphere with highest enhancements of about 60 ppt y in the lowermost mesosphere over the Jan. 16-18, 2005 period due to the solar protons. WACCM3 predictions indicate H2O2 enhancements over the same time period of more than twice that amount. Measurements of nitric acid (HNO3) by both MLS and MIPAS show an increase of about 1 ppbv above background levels in the upper stratosphere during January 16-29, 2005. WACCM3 simulations show only minuscule HNO3 changes in the upper stratosphere during this time period. However due to the small loss rates during winter, polar mesospheric enhancements of NO(x) are computed to be greater than 50 ppbv during the SPE period. Computed NO(x)increases, which were statistically significant at the 95% level, lasted about a month past the SPEs. The SCISAT-I Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) NO(x) measurements and MIPAS NO, measurements for the polar Northern Hemisphere are in reasonable agreement with these predictions. An extremely large ground level enhancement (GLE) occurred during the SPE period on January 20, 2005. We find that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced lower stratospheric odd nitrogen concentrations of less than 0.1% as a result of this GLE.

Jackman, C. H.; Marsh, D. R.; Vitt, F. M.; Roble, R. G.; Randall, C. E.; Bernath, P. F.; Funke, B.; Lopez-Puertas, M.; Versick, S.; Stiller, G. P.; Tylka, A. J.; Fleming, E. L.

2011-01-01

314

Do aerosols influence the diurnal variation of H2O2 in the atmosphere?  

NASA Astrophysics Data System (ADS)

Hydrogen peroxide (H2O2) and organic peroxides are crucial reactive species that are involved in the cycling of HOx (OH and HO2) radicals and the formation of secondary inorganic and organic aerosols in the atmosphere. Despite the importance of peroxides, their formation and removal mechanisms with the coexistence of aerosols are as yet less well known. From June 10 to July 15 2013, summertime surface measurements for atmospheric peroxides were simultaneously obtained in urban Beijing (UB) and Gucheng (GC). The UB site is located in the northern downtown of Beijing city, while the GC site is a rural site located in the North China Plain and ~100 km southwest of Beijing. In both sites, the major peroxides were determined to be H2O2, methyl hydroperoxide (MHP), peroxyformic acid (PFA) and peroxyacetic acid (PAA). By comparing the concentrations of PFA and PAA in the gas phase and rainwater, for the first time, we estimated the Henry's law constant for PFA as ~210 M atm-1 at 298 K, a quarter of that for PAA. Interestingly, we observed different H2O2 profiles in the two sites as follows: (i) the average concentration of H2O2 in UB was 50% higher than that in GC; (ii) H2O2 in GC reached its peak concentration at around 15:30, whereas the peak concentration in UB appeared at as late as 21:00; and (iii) the daily variation of H2O2 in GC generally kept consistent with that of O3 and organic peroxides while it was not always the case in UB. These differences indicate a hitherto unrecognized storage-release mechanism for H2O2 in UB, that is, an extra sink in the noontime and an extra source in the early evening. The extra source of H2O2 would enhance the aerosol phase OH radical in the early evening by the Fenton reaction. A box model analysis shows that the impacts of aerosols were majorly responsible to this unrecognized mechanism, although NOx, regional transport and planet boundary layer height also contributed a minor part. Aerosols participated in the storage-release mechanism in two potential ways. The first is the catalytic reaction of aerosol-phase soluble transition metal ions (ATMIs). ATMIs could convert HO2 to either H2O or H2O2, depending on their abundance and composition. In UB, the high ATMIs are presumed to convert most HO2 to H2O in the noontime and to H2O2 in the early evening, resulting in a different diurnal profile of H2O2. The second is the formation and hydrolysis of H2O2-related complex. In the noontime, H2O2 could be taken up onto the aerosols and then combine with organic matters to form complexes such as hydroxyalkyl hydroperoxides and secondary organic aerosols. In the early evening, however, these complexes could hydrolyze to generate H2O2 and release into the gas phase. The impacts of aerosols on H2O2, and probably on HO2 radicals over the polluted regions should be taken into consideration in the atmospheric model.

Liang, H.; Chen, Z.; Wu, Q.; Huang, D.; Zhao, Y.

2013-12-01

315

Strong control of surface roughness variations on the simulated dry season regional atmospheric response to contemporary deforestation in Rondônia, Brazil  

NASA Astrophysics Data System (ADS)

AbstractThe <span class="hlt">atmospheric</span> effects of Amazon deforestation have frequently been studied in the context of small scales (?1 km) and very large scales (hundreds of kilometers). However, analysis of intermediate-scale deforestation (tens of kilometers) has received less attention, despite the fact that it better represents the contemporary landscape in some parts of the Amazon. In this study, the dynamic and thermodynamic effects of contemporary intermediate-scale deforestation in Rondônia, Brazil are investigated through variable resolution Global Circulation Model (GCM) simulations carried out with the Ocean-Land-<span class="hlt">Atmosphere</span> Model. In particular, the <span class="hlt">atmospheric</span> response to surface roughness changes brought about by deforestation is emphasized. This study shows that reductions in surface roughness associated with intermediate-scale deforestation give rise to a mesoscale circulation. This circulation is capable of convective triggering, but it also weakens the turbulent exchange of energy between land and <span class="hlt">atmosphere</span>. Furthermore, this mesoscale circulation has distinct impacts on the hydroclimates of the western and eastern halves of Rondônia, increasing shallow cloudiness in the former while suppressing it in the latter. These results show that the <span class="hlt">atmospheric</span> response to contemporary intermediate-scale deforestation in Rondônia is likely to be more <span class="hlt">influenced</span> by differences in surface roughness between forest and forest clearings than by the differences in the surface energy partitioning.</p> <div class="credits"> <p class="dwt_author">Khanna, Jaya; Medvigy, David</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">316</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=187186"> <span id="translatedtitle">OUTSTANDING ISSUES REGARDING THE ROLE OF <span class="hlt">ATMOSPHERIC</span> AEROSOLS ON TERRESTRIAL BIOSPHERE AND <span class="hlt">REGIONAL</span> CLIMATE</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p class="result-summary"><span class="hlt">Atmospheric</span> aerosols have a complex feedback on the earth’s climate. Past studies related to studying the impact of aerosols on the earth’s climate had focused on upper <span class="hlt">atmospheric</span> processes including cloud-aerosol- radiative interactions. Recent evidence from field and model studies indicates that ...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">317</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/1081763"> <span id="translatedtitle"><span class="hlt">Influence</span> of vegetation and seasonal forcing on carbon dioxide fluxes across the Upper Midwest, USA: Implications for <span class="hlt">regional</span> scaling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Carbon dioxide fluxes were examined over the growing seasons of 2002 and 2003 from 14 different sites in Upper Midwest (USA) to assess spatial variability of ecosystem <span class="hlt">atmosphere</span> CO2 exchange. These sites were exposed to similar temperature/precipitation regimes and spanned a range of vegetation types typical of the <span class="hlt">region</span> (northern hardwood, mixed forest, red pine, jack pine, pine barrens and shrub wetland). The hardwood and red pine sites also spanned a range of stand ages (young, intermediate, mature). While seasonal changes in net ecosystem exchange (NEE) and photosynthetic parameters were coherent across the 2 years at most sites, changes in ecosystem respiration (ER) and gross ecosystem production (GEP) were not. Canopy height and vegetation type were important variables for explaining spatial variability of CO2 fluxes across the <span class="hlt">region</span>. Light-use efficiency (LUE) was not as strongly correlated to GEP as maximum assimilation capacity (Amax). A bottom-up multi-tower land cover aggregated scaling of CO2 flux to a 2000 km2 <span class="hlt">regional</span> flux estimate found June to August 2003 NEE, ER and GEP to be 290 89, 408, 48, and 698, 73 gC m-2, respectively. Aggregated NEE, ER and GEP were 280% larger, 32% smaller and 3% larger, respectively, than that observed from a <span class="hlt">regionally</span> integrating 447m tall flux tower. However, when the tall tower fluxes were decomposed using a footprint-weighted <span class="hlt">influence</span> function and then reaggregated to a <span class="hlt">regional</span> estimate, the resulting NEE, ER and GEP were within 11% of the multi-tower aggregation. Excluding wetland and young stand age sites from the aggregation worsened the comparison to observed fluxes. These results provide insight on the range of spatial sampling, replication, measurement error and land cover accuracy needed for multi-tiered bottom-up scaling of CO2 fluxes in heterogeneous <span class="hlt">regions</span> such as the Upper Midwest, USA.</p> <div class="credits"> <p class="dwt_author">Desai, Desai Ankur R. [University of Wisconsin, Madison; Noormets, Asko [North Carolina State University; Bolstad, Paul V [University of Minnesota; Chen, Jiquan [University of Toledo, Toledo, OH; Cook, Bruce D [University of Minnesota, St Paul; Davis, Kenneth [Pennsylvania State University; Euskirchen, Eugenie S [University of Alaska; Gough, Christopher M [Ohio State University; Martin, Jonathan G [Oregon State University, Corvallis; Ricciuto, Daniel M [ORNL; Schmid, Hans Peter [Indiana University; Tang, Jianwu [Chicago Botanical Garden, Glencoe, Illiinois; Wang, Weiguo [Pacific Northwest National Laboratory (PNNL)</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">318</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1611156J"> <span id="translatedtitle"><span class="hlt">Influence</span> of <span class="hlt">Atmospheric</span> Modes of Variability on Mediterranean Sea Surface Heat Exchange from a 12km Dynamically Downscaled Reanalysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Earlier research on the impacts of the first four modes of <span class="hlt">atmospheric</span> variability in the North Atlantic / Europe <span class="hlt">region</span> on air-sea heat exchange in the Mediterranean Sea will be extended to higher spatial resolution using the ALADIN 12 km dynamical downscaling of the ERA-Interim reanalysis. Observation based indices of the modes from the NOAA Climate Prediction Centre (CPC) are used together with the 12 km ALADIN surface flux fields for the period 1979-2012 to determine the sensitivity of the mean heat budget of the full Mediterranean basin and the eastern and western sub-basins to surface forcing at higher resolutions than previously considered. The four modes are the North Atlantic Oscillation (NAO), East Atlantic pattern (EA), Scandinavian pattern (SCAN) and East Atlantic / West Russian pattern (EA/WR). Results at coarser resolution using the NCEP/NCAR and 50 km resolution ARPERA reanalysis will also be reviewed. These indicate that winter anomalies dominate the annual mean heat budget and the leading mode, the NAO, has a surprisingly small impact on the full basin winter mean heat budget, < 5 Wm-2. In contrast, the EA mode has a major effect, of order 25 Wm-2, with similar impacts on both the eastern and western Mediterranean. The SCAN mode has the weakest <span class="hlt">influence</span> of those considered. The EA/WR mode plays a significant role but, in contrast to the EA mode, it generates a dipole in the heat exchange with an approximately equal and opposite signal of about 15 Wm-2 on the eastern and western sub-basins. New results will be presented which reveal the extent to which these earlier conclusions still hold at the higher 12km resolution now possible using ALADIN.</p> <div class="credits"> <p class="dwt_author">Josey, Simon; Somot, Samuel</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">319</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014psce.conf..151S"> <span id="translatedtitle"><span class="hlt">Influence</span> of departures from LTE on oxygen and calcium abundance determination in the <span class="hlt">atmospheres</span> of A-K stars.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Comprehensive model atoms for O I and Ca I -Ca II were applied to evaluate the <span class="hlt">influence</span> of the departures from LTE upon O and Ca abundance determinations for a wide range of spectral types. It was found that non-LTE line formation led to large negative abundance corrections for the infrared O I ? 7771-5 Å triplet lines, while the non-LTE correction does not exceed 0.05 dex in absolute value for O I lines in the visible <span class="hlt">region</span> for main-sequence stars. For Ca II, the sign and magnitude of the NLTE correction depends on the line in question and on the stellar parameters. As a test of the non-LTE method, O and Ca abundances were derived for a few A-type stars with well determined parameters. It was found that non-LTE largely removes the differences in abundances between the infrared O I ? 7771-5 Å and visible O I lines which are obtained when LTE is assumed. For example, for Vega, the difference of 1.23 dex in LTE is reduced to 0.14 dex in non-LTE. For each star investigated, the calcium abundances determined in non-LTE from lines of the two ionization stages (Ca I and Ca II) were consistent within the error bars, in contrast to the LTE case, where (Ca I - Ca II) can range from -0.13 to +0.14 for different stars. Non-LTE abundance corrections for oxygen and calcium lines have been calculated for a grid of model <span class="hlt">atmospheres</span> encompassing a wide range of stellar parameters.</p> <div class="credits"> <p class="dwt_author">Sitnova, T.; Mashonkina, L.; Ryabchikova, T.; Pakhomov, Yu.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">320</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21185903"> <span id="translatedtitle"><span class="hlt">Influence</span> of base pressure and <span class="hlt">atmospheric</span> contaminants on a-Si:H solar cell properties</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The <span class="hlt">influence</span> of <span class="hlt">atmospheric</span> contaminants oxygen and nitrogen on the performance of thin-film hydrogenated amorphous silicon (a-Si:H) solar cells grown by plasma-enhanced chemical vapor deposition at 13.56 MHz was systematically investigated. The question is addressed as to what degree of high base pressures (up to 10{sup -4} Torr) are compatible with the preparation of good quality amorphous silicon based solar cells. The data show that for the intrinsic a-Si:H absorber layer exists critical oxygen and nitrogen contamination levels (about 2x10{sup 19} atoms/cm{sup 3} and 4x10{sup 18} atoms/cm{sup 3}, respectively). These levels define the minimum impurity concentration that causes a deterioration in solar cell performance. This critical concentration is found to depend little on the applied deposition regime. By enhancing, for example, the flow of process gases, a higher base pressure (and leak rate) can be tolerated before reaching the critical contamination level. The electrical properties of the corresponding films show that increasing oxygen and nitrogen contamination results in an increase in dark conductivity and photoconductivity, while activation energy and photosensitivity are decreased. These effects are attributed to nitrogen and oxygen induced donor states, which cause a shift of the Fermi level toward the conduction band and presumably deteriorate the built-in electric field in the solar cells. Higher doping efficiencies are observed for nitrogen compared to oxygen. Alloying effects (formation of SiO{sub x}) are observed for oxygen contaminations above 10{sup 20} atoms/cm{sup 3}, leading to an increase in the band gap.</p> <div class="credits"> <p class="dwt_author">Woerdenweber, J.; Schmitz, R.; Mueck, A.; Zastrow, U.; Niessen, L.; Gordijn, A.; Carius, R.; Beyer, W.; Rau, U. [IEF 5 Photovoltaik, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Merdzhanova, T.; Stiebig, H. [IEF 5 Photovoltaik, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Malibu GmbH and Co. KG, Boettcherstr. 7, D-33609 Bielefeld (Germany)</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-11-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a 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href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a style="font-weight: bold;">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_18");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next 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characteristics of the sporadic E (Es) layer, that is the top frequency (ftEs) and the lowest virtual height (h'Es). The study is based on ionograms recorded by the Advanced Ionospheric Sounder by the Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed in the ionospheric stations at Rome (41.8° N, 12.5° E) and Gibilmanna (37.9° N, 14.0° E), Italy, during the summer (June, July, August and September) of 2013, a year falling in the ascending phase of solar cycle 24. The ftEs presents a diurnal variation characterized by two maxima, the first around noon is very well defined and the second in the evening/night is much less defined; the amplitude of both maxima decreases from June to September accompanied by a general decrease of the ftEs values which is more pronounced in the daytime than in the nighttime. h'Es also presents a diurnal variation characterized by two maxima but, unlike ftEs, these present the same amplitude which is independent from the considered month. Assuming that both ftEs and h'Es trends are <span class="hlt">influenced</span> by the <span class="hlt">atmospheric</span> tides, the height-time-intensity (HTI) technique was applied to deeply investigate how these waves control the Es dynamics. The HTI study, along with a fast Fourier transform analysis, show that a well-defined semidiurnal periodicity characterizes the Es layer dynamics most accurately in June and July, while in August and September the daytime semidiurnal periodicity becomes weaker and the role of the diurnal periodicity is consequently highlighted.</p> <div class="credits"> <p class="dwt_author">Pignalberi, A.; Pezzopane, M.; Zuccheretti, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">322</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21443630"> <span id="translatedtitle"><span class="hlt">Influence</span> of the voltage polarity on the properties of a nanosecond surface barrier discharge in <span class="hlt">atmospheric</span>-pressure air</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The properties of a surface barrier discharge in <span class="hlt">atmospheric</span>-pressure air at different polarities of applied voltage were studied experimentally. The <span class="hlt">influence</span> of the voltage polarity on the spatial structure of the discharge and the electric field in the discharge plasma was determined by means of spectroscopic measurements. It is found that the energy deposited in the discharge does not depend on the voltage polarity and that discharges of positive polarity are more homogenous and the electric fields in them are higher.</p> <div class="credits"> <p class="dwt_author">Nudnova, M. M.; Aleksandrov, N. L. [Moscow Institute of Physics and Technology (Russian Federation); Starikovskii, A. Yu. [Drexel University (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-15</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">323</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/c8k0528u53856575.pdf"> <span id="translatedtitle">Short-term variations of vapor isotope ratios reveal the <span class="hlt">influence</span> of <span class="hlt">atmospheric</span> processes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Stable isotopes of <span class="hlt">atmospheric</span> water vapor reveal rich information on water movement and phase changes in the <span class="hlt">atmosphere</span>.\\u000a Here we presented two nearly continuous time-series of ?D and ?\\u000a 18O of <span class="hlt">atmospheric</span> water vapor (?\\u000a v) measured at hourly intervals in surface air in Beijing and above a winter wheat canopy in Shijiazhuang using in-situ measurement\\u000a technique. During the precipitation</p> <div class="credits"> <p class="dwt_author">Shichun Zhang; Xiaomin Sun; Jianlin Wang; Guirui Yu; Xuefa Wen</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">324</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22036944"> <span id="translatedtitle">EVIDENCE FOR WIDESPREAD COOLING IN AN ACTIVE <span class="hlt">REGION</span> OBSERVED WITH THE SDO <span class="hlt">ATMOSPHERIC</span> IMAGING ASSEMBLY</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A well-known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active <span class="hlt">regions</span> (ARs). Is this cooling pattern a common property of AR coronal plasma, or does it only occur in unique circumstances, locations, and times? The new Solar Dynamics Observatory/<span class="hlt">Atmospheric</span> Imaging Assembly (SDO/AIA) data provide a wonderful opportunity to answer this question systematically for an entire AR. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hr of images of AR 11082 observed on 2010 June 19. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the AR including the diffuse emission between loops for the entire 24 hr duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hr time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than {approx}0.8 MK. This suggests that the bulk of the emitting coronal plasma in this AR is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.</p> <div class="credits"> <p class="dwt_author">Viall, Nicholeen M.; Klimchuk, James A. [NASA Goddard Space Flight Center, Solar Physics Laboratory, Greenbelt, MD 20706 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">325</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ACP....1412683N"> <span id="translatedtitle"><span class="hlt">Atmospheric</span> black carbon and warming effects <span class="hlt">influenced</span> by the source and absorption enhancement in central Europe</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Particles containing black carbon (BC), a strong absorbing substance, exert a rather uncertain direct and indirect radiative forcing in the <span class="hlt">atmosphere</span>. To investigate the mass concentration and absorption properties of BC particles over central Europe, the model WRF-Chem was used at a resolution of 12 km in conjunction with a high-resolution BC emission inventory (EUCAARI 42-Pan-European Carbonaceous Aerosol Inventory; 1/8° × 1/16°). The model simulation was evaluated using measurements of equivalent soot carbon, absorption coefficients and particle number concentrations at seven sites within the German Ultrafine Aerosol Network, PM<sub<10 mass concentrations from the dense measurement network of the German Federal Environmental Agency at 392 monitoring stations, and aerosol optical depth from MODIS and AERONET. A distinct time period (25 March to 10 April 2009) was chosen, during which the clean marine air mass prevailed in the first week and afterwards the polluted continental air mass mainly from the southeast dominated with elevated daily average BC concentration of up to 4 ? g m-3. The simulated PM<sub<10 mass concentration, aerosol number concentration and optical depth were in good agreement with the observations, while the modelled BC mass concentrations were found to be a factor of 2 lower than the observations. Together with back trajectories, detailed model bias analyses suggested that the current BC emission in countries to the east and south of Germany might be underestimated by a factor of 5, at least for the simulation period. Running the model with upscaled BC emissions in these <span class="hlt">regions</span> led to a smaller model bias and a better correlation between model and measurement. In contrast, the particle absorption coefficient was positively biased by about 20% even when the BC mass concentration was underestimated by around 50%. This indicates that the internal mixture treatment of BC in the WRF-Chem optical calculation is unrealistic in our case, which overamplifies the light absorption by BC-containing particles. By adjusting the modelled mass absorption cross-section towards the measured values, the simulation of particle light absorption of BC was improved as well. Finally, the positive direct radiative forcing of BC particles at the top of the <span class="hlt">atmosphere</span> was estimated to be in the range of 0 to +4 W m-2 over Germany for the model run with improved BC mass concentration and adjusted BC light absorption cross-section. This adjustment lowered the positive forcing of BC by up to 70%, compared with the internal mixing treatment of BC in the model simulation.</p> <div class="credits"> <p class="dwt_author">Nordmann, S.; Cheng, Y. F.; Carmichael, G. R.; Yu, M.; Denier van der Gon, H. A. C.; Zhang, Q.; Saide, P. E.; Pöschl, U.; Su, H.; Birmili, W.; Wiedensohler, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">326</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014CliPa..10.1925M"> <span id="translatedtitle">The <span class="hlt">influence</span> of <span class="hlt">atmospheric</span> circulation on the mid-Holocene climate of Europe: a data-model comparison</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">atmospheric</span> circulation is a key area of uncertainty in climate model simulations of future climate change, especially in mid-latitude <span class="hlt">regions</span> such as Europe where <span class="hlt">atmospheric</span> dynamics have a significant role in climate variability. It has been proposed that the mid-Holocene was characterized in Europe by a stronger westerly circulation in winter comparable with a more positive AO/NAO, and a weaker westerly circulation in summer caused by anti-cyclonic blocking near Scandinavia. Model simulations indicate at best only a weakly positive AO/NAO, whilst changes in summer <span class="hlt">atmospheric</span> circulation have not been widely investigated. Here we use a new pollen-based reconstruction of European mid-Holocene climate to investigate the role of <span class="hlt">atmospheric</span> circulation in explaining the spatial pattern of seasonal temperature and precipitation anomalies. We find that the footprint of the anomalies is entirely consistent with those from modern analogue <span class="hlt">atmospheric</span> circulation patterns associated with a strong westerly circulation in winter (positive AO/NAO) and a weak westerly circulation in summer associated with anti-cyclonic blocking (positive SCAND). We find little agreement between the reconstructed anomalies and those from 14 GCMs that performed mid-Holocene experiments as part of the PMIP3/CMIP5 project, which show a much greater sensitivity to top-of-the-<span class="hlt">atmosphere</span> changes in solar insolation. Our findings are consistent with data-model comparisons on contemporary timescales that indicate that models underestimate the role of <span class="hlt">atmospheric</span> circulation in recent climate change, whilst also highlighting the importance of <span class="hlt">atmospheric</span> dynamics in explaining interglacial warming.</p> <div class="credits"> <p class="dwt_author">Mauri, A.; Davis, B. A. S.; Collins, P. M.; Kaplan, J. O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">327</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70029425"> <span id="translatedtitle">An analysis of <span class="hlt">region-of-influence</span> methods for flood <span class="hlt">regionalization</span> in the Gulf-Atlantic Rolling Plains</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary"><span class="hlt">Region-of-influence</span> (RoI) approaches for estimating streamflow characteristics at ungaged sites were applied and evaluated in a case study of the 50-year peak discharge in the Gulf-Atlantic Rolling Plains of the southeastern United States. Linear regression against basin characteristics was performed for each ungaged site considered based on data from a <span class="hlt">region</span> of <span class="hlt">influence</span> containing the n closest gages in predictor variable (PRoI) or geographic (GRoI) space. Augmentation of this count based cutoff by a distance based cutoff also was considered. Prediction errors were evaluated for an independent (split-sampled) dataset. For the dataset and metrics considered here: (1) for either PRoI or GRoI, optimal results were found when the simpler count based cutoff, rather than the distance augmented cutoff, was used; (2) GRoI produced lower error than PRoI when applied indiscriminately over the entire study <span class="hlt">region</span>; (3) PRoI performance improved considerably when RoI was restricted to predefined geographic subregions.</p> <div class="credits"> <p class="dwt_author">Eng, K.; Tasker, G.D.; Milly, P.C.D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">328</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.esf.edu/hss/HF%20Ref%20PDF/EnvSci.39.787.794.pdf"> <span id="translatedtitle"><span class="hlt">Regional</span> Assessment of the Response of the AcidBase Status of Lake Watersheds in the Adirondack <span class="hlt">Region</span> of New York to Changes in <span class="hlt">Atmospheric</span> Deposition Using PnET-BGC</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Understanding the response of soil and surface waters to changes in <span class="hlt">atmospheric</span> deposition is critical for guiding future legislation on air pollution. The Adirondack <span class="hlt">region</span> of New York experiences among the most severe ecological impacts from acidic deposition. The <span class="hlt">region</span> is characterized by considerable variability in <span class="hlt">atmospheric</span> deposition, surficial and bedrock geology, hydrologic flow paths, and vegetation resulting in variability</p> <div class="credits"> <p class="dwt_author">LIMIN C HEN; CHARLES T. D RISCOLL</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">329</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ecd.bnl.gov/steve/pubs/ARM_Aerosol_IOP.pdf"> <span id="translatedtitle">The <span class="hlt">Atmospheric</span> Radiation Measurement Program May 2003 Intensive Operations Period Examining Aerosol Properties and Radiative <span class="hlt">Influences</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">and scattering 0394 Instruments and techniques 0300 <span class="hlt">Atmospheric</span> composition and structure 1 NASA Langley Research1 The <span class="hlt">Atmospheric</span> Radiation Measurement Program May 2003 Intensive Operations Period Examining/CMDL, 325 Broadway R/CMDL1, Boulder, CO, 80305, USA 5 BAER Institute/NASA Ames Research Center, MS 245</p> <div class="credits"> <p class="dwt_author">Schwartz, Stephen E.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">330</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=255909"> <span id="translatedtitle"><span class="hlt">Influence</span> of elevated <span class="hlt">atmospheric</span> CO2 and tillage practice on rainfall simulation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p class="result-summary">No work has investigated whether increasing <span class="hlt">atmospheric</span> CO2 concentration will impact sediment loss in agricultural systems. Rainfall simulation was conducted following a 10-year study investigating the effects of <span class="hlt">atmospheric</span> CO2 level (ambient and twice ambient) in two cropping systems (conventiona...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">331</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52562958"> <span id="translatedtitle"><span class="hlt">Influence</span> of the greenhouse effect in primordial <span class="hlt">atmospheres</span> on the formation of the earth and Venus</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The greenhouse effect in the primordial <span class="hlt">atmospheres</span> possibly formed by degassing of volatile materials in the interiors of the earth and Venus which mainly contained CO2 and H2O in the ratio of 1 to 4. It was shown that the earth <span class="hlt">atmosphere</span> greenhouse effect could not have resulted in the heating of its surface to temperatures above those of boiling</p> <div class="credits"> <p class="dwt_author">D. D. Kvasov; A. P. Galtsev; A. S. Safrai</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">332</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012IzAOP..48..355S"> <span id="translatedtitle"><span class="hlt">Influence</span> of the ocean surface temperature and sea ice concentration on <span class="hlt">regional</span> climate changes in Eurasia in recent decades</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Numerical experiments with the ECHAM5 <span class="hlt">atmospheric</span> general circulation model have been performed in order to simulate the <span class="hlt">influence</span> of changes in the ocean surface temperature (OST) and sea ice concentration (SIC) on climate characteristics in <span class="hlt">regions</span> of Eurasia. The sensitivity of winter and summer climates to OST and SIC variations in 1998-2006 has been investigated and compared to those in 1968-1976. These two intervals correspond to the maximum and minimum of the Atlantic Long-Period Oscillation (ALO) index. Apart from the experiments on changes in the OST and SIC global fields, the experiments on OST anomalies only in the North Atlantic and SIC anomalies in the Arctic for the specified periods have been analyzed. It is established that temperature variations in Western Europe are explained by OST and SIC variations fairly well, whereas the warmings in Eastern Europe and Western Siberia, according to model experiments, are substantially (by a factor of 2-3) smaller than according to observational data. Winter changes in the temperature regime in continental <span class="hlt">regions</span> are controlled mainly by <span class="hlt">atmospheric</span> circulation anomalies. The model, on the whole, reproduces the empirical structure of changes in the winter field of surface pressure, in particular, the pressure decrease in the Caspian <span class="hlt">region</span>; however, it substantially (approximately by three times) underestimates the range of changes. Summer temperature variations in the model are characterized by a higher statistical significance than winter ones. The analysis of the sensitivity of the climate in Western Europe to SIC variations alone in the Arctic is an important result of the experiments performed. It is established that the SIC decrease and a strong warming over the Barents Sea in the winter period leads to a cooling over vast <span class="hlt">regions</span> of the northern part of Eurasia and increases the probability of anomalously cold January months by two times and more (for <span class="hlt">regions</span> in Western Siberia). This effect is caused by the formation of the increased-pressure <span class="hlt">region</span> with a center over the southern boundary of the Barents Sea during the SIC decrease and an anomalous advection of cold air masses from the northeast. This result indicates that, to estimate the ALO actions (as well as other long-scale climatic variability modes) on the climate of Eurasia, it is basically important to take into account (or correctly reproduce) Arctic sea ice changes in experiments with climatic models.</p> <div class="credits"> <p class="dwt_author">Semenov, V. A.; Mokhov, I. I.; Latif, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">333</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://coweeta.uga.edu/publications/10327.pdf"> <span id="translatedtitle">Flood Disturbance Regimes <span class="hlt">Influence</span> Rainbow Trout Invasion Success among Five Holarctic <span class="hlt">Regions</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">There is growing awareness that predicting biological invasions will require the development of conceptual models for specific taxa at appropriate scales. Salmonids are ideal taxa for testing factors that <span class="hlt">influence</span> invasions, because large numbers have been introduced worldwide for long periods and their ecology is well known. We evaluated the hypothesis that, among <span class="hlt">regions</span> with suitable water temperatures, environmental resistance</p> <div class="credits"> <p class="dwt_author">Kurt D. Fausch; Yoshinori Taniguchi; Shigeru Nakano; Gary D. Grossman; Colin R. Townsend</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">334</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.cgd.ucar.edu/ccr/ahu/papers/paper2_res.pdf"> <span id="translatedtitle">NAO <span class="hlt">influence</span> on net sea ice production and exchanges in the Arctic <span class="hlt">region</span>: a numerical study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">NAO <span class="hlt">influence</span> on net sea ice production and exchanges in the Arctic <span class="hlt">region</span>: a numerical study Aixue The variability of net sea ice production and sea ice exchange between the Arctic and its adjacent seas are studied, using a coupled sea ice-ocean general circulation model. The wind driven divergence (or ice flux</p> <div class="credits"> <p class="dwt_author">Hu, Aixue</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">335</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=literacy&pg=7&id=EJ1028916"> <span id="translatedtitle">Global, <span class="hlt">Regional</span> and Local <span class="hlt">Influences</span> on Adult Literacy Policy in England</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">This paper explores the relationship between global, <span class="hlt">regional</span> and local <span class="hlt">influences</span> on adult literacy policy and practice in the UK through a discourse analysis of policy-related texts. The analysis is framed by theoretical perspectives from literacy studies and socio-material theory. The paper identifies a number of specific features in the UK…</p> <div class="credits"> <p class="dwt_author">Hamilton, Mary</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">336</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/57793053"> <span id="translatedtitle">Natural Disturbances and Fish: Local and <span class="hlt">Regional</span> <span class="hlt">Influences</span> on Winterkill of Fathead Minnows in Boreal Lakes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We investigated the population dynamics of fathead minnow Pimephales promelas and the environmental factors of four small lakes in the boreal forest of Alberta, Canada, for 5 years to determine the <span class="hlt">influence</span> of local and <span class="hlt">regional</span> factors on the development of hypoxia and the occurrence of fish winterkill. Fathead minnow densities varied considerably among lakes and years, with dramatic (47–94%)</p> <div class="credits"> <p class="dwt_author">Andy J. Danylchuk; William M. Tonn</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">337</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4183387"> <span id="translatedtitle"><span class="hlt">Regional</span> Variation of Climatic <span class="hlt">Influences</span> on West Nile Virus Outbreaks in the United States</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">The national resurgence of human West Nile virus (WNV) disease in 2012 raised questions about the factors responsible for WNV outbreaks. Interannual climatic variations may <span class="hlt">influence</span> WNV amplification and transmission to humans through multiple pathways, including mosquito breeding habitats, gonotrophic cycles, extrinsic incubation, avian communities, and human behavior. We examined the <span class="hlt">influences</span> of temperature and precipitation anomalies on interannual variation in human WNV cases in three <span class="hlt">regions</span> of the United States. There were consistent positive <span class="hlt">influences</span> of winter temperatures, weaker and more variable positive effects of spring and summer temperatures, and highly variable precipitation effects that ranged from positive to negative. The overwintering period may be a particularly important climatic constraint on the dynamics of WNV in cold-temperate <span class="hlt">regions</span> of North America. Geographic differences in the seasonal timing and relative importance of climatic drivers of WNV risk likely reflect underlying variability in key ecological and social characteristics. PMID:25092814</p> <div class="credits"> <p class="dwt_author">Wimberly, Michael C.; Lamsal, Aashis; Giacomo, Paolla; Chuang, Ting-Wu</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">338</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27000566"> <span id="translatedtitle">A modified split-anode detector for the study of the anode <span class="hlt">region</span> of <span class="hlt">atmospheric</span> pressure arc plasmas</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The split-anode technique developed in the 1960s for the study of the anode <span class="hlt">region</span> of <span class="hlt">atmospheric</span> pressure arcs has been modified in order to reduce (and subsequently eliminate) the need for double Abel inversion to reconstruct the local physical information. A first version of a detector based on a conductive sheet is presented and the performances of the new set-up</p> <div class="credits"> <p class="dwt_author">L. O. Vilarinho; C. Fanara</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">339</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.3243G"> <span id="translatedtitle">Anthropogenic <span class="hlt">Influence</span> on Secondary Aerosol Formation and Total Water-Soluble Carbon on <span class="hlt">Atmospheric</span> Particles</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">On a global scale, the <span class="hlt">atmosphere</span> is an important source of nutrients, as well as pollutants, because of its interfaces with soil and water. Important compounds in the gaseous phase are in both organic and inorganic forms, such as organic acids, nitrogen, sulfur and chloride. In spite of the species in gas form, a huge number of process, anthropogenic and natural, are able to form aerosols, which may be transported over long distances. Sulfates e nitrates are responsible for rain acidity; they may also increase the solubility of organic compounds and metals making them more bioavailable, and also can act as cloud condensation nuclei (CCN). Aerosol samples (PM2.5) were collected in a rural and industrial area in Rio de Janeiro, Brazil, in order to quantify chemical species and evaluate anthropogenic <span class="hlt">influences</span> in secondary aerosol formation and organic compounds. Samples were collected during 24 h every six days using a high-volume sampler from August 2010 to July 2011. The aerosol mass was determined by Gravimetry. The water-soluble ionic composition (WSIC) was obtained by Ion Chromatography in order to determine the major anions (NO3-, SO4= and Cl-); total water-soluble carbon (TWSC) was determined by a TOC analyzer. The average aerosol (PM2.5) concentrations ranged from 1 to 43 ug/m3 in the industrial site and from 4 to 35 ug/m3 in the rural area. Regarding anions, the highest concentrations were measured for SO42- (10.6 ?g/m3-12.6 ?g/m3); where the lowest value was found in the rural site and the highest in the industrial. The concentrations for NO3- and Cl- ranged from 4.2 ?g/m3 to 9.3 ?g/m3 and 3.1 ?g/m3 to 6.4 ?g /m3, respectively. Sulfate was the major species and, like nitrate, it is related to photooxidation in the <span class="hlt">atmosphere</span>. Interestingly sulfate concentrations were higher during the dry period and could be related to photochemistry activity. The correlations between nitrate and non-sea-salt sulfate were weak, suggesting different sources for these species. The secondary aerosol represented an important fraction of total compounds in PM2.5 ranged from 16 to 18% for (NH4)2SO4 and 6 to 8% for NH4NO3. The values for TWSC ranged from 0.28 to 6.35 ?g/m3 in the industrial area and 0.12 to 7.49 ?g/m3 for rural area. The similarity between the areas regarding secondary aerosols formation and water-soluble carbon compounds is probably due to the particle size.</p> <div class="credits"> <p class="dwt_author">Gioda, Adriana; Mateus, Vinicius; Monteiro, Isabela; Taira, Fabio; Esteves, Veronica; Saint'Pierre, Tatiana</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">340</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22611187"> <span id="translatedtitle">Assessment of ground-based <span class="hlt">atmospheric</span> observations for verification of greenhouse gas emissions from an urban <span class="hlt">region</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">International agreements to limit greenhouse gas emissions require verification to ensure that they are effective and fair. Verification based on direct observation of <span class="hlt">atmospheric</span> greenhouse gas concentrations will be necessary to demonstrate that estimated emission reductions have been actualized in the <span class="hlt">atmosphere</span>. Here we assess the capability of ground-based observations and a high-resolution (1.3 km) mesoscale <span class="hlt">atmospheric</span> transport model to determine a change in greenhouse gas emissions over time from a metropolitan <span class="hlt">region</span>. We test the method with observations from a network of CO(2) surface monitors in Salt Lake City. Many features of the CO(2) data were simulated with excellent fidelity, although data-model mismatches occurred on hourly timescales due to inadequate simulation of shallow circulations and the precise timing of boundary-layer stratification and destratification. Using two optimization procedures, monthly <span class="hlt">regional</span> fluxes were constrained to sufficient precision to detect an increase or decrease in emissions of approximately 15% at the 95% confidence level. We argue that integrated column measurements of the urban dome of CO(2) from the ground and/or space are less sensitive than surface point measurements to the redistribution of emitted CO(2) by small-scale processes and thus may allow for more precise trend detection of emissions from urban <span class="hlt">regions</span>. PMID:22611187</p> <div class="credits"> <p class="dwt_author">McKain, Kathryn; Wofsy, Steven C; Nehrkorn, Thomas; Eluszkiewicz, Janusz; Ehleringer, James R; Stephens, Britton B</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-05-29</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' 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id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a style="font-weight: bold;">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_19");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">341</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19910058292&hterms=atmospheric+boundary+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Datmospheric%2Bboundary%2Blayer"> <span id="translatedtitle">A bulk similarity approach in the <span class="hlt">atmospheric</span> boundary layer using radiometric skin temperature to determine <span class="hlt">regional</span> surface fluxes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Profiles of wind velocity and temperature in the outer <span class="hlt">region</span> of the <span class="hlt">atmospheric</span> boundary layer (ABL) were used together with surface temperature measurements, to determine <span class="hlt">regional</span> shear stress and sensible heat flux by means of transfer parameterizations on the basis of bulk similarity. The profiles were measured by means of radiosondes and the surface temperatures by infrared radiation thermometry over hilly prairie terrain in northeastern Kansas during the First ISLSCP Field Experiment (FIFE). In the analysis, the needed similarity functions were determined and tested.</p> <div class="credits"> <p class="dwt_author">Brutsaert, Wilfried; Sugita, Michiaki</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">342</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://dspace.mit.edu/handle/1721.1/87722"> <span id="translatedtitle">Coupling of a <span class="hlt">regional</span> <span class="hlt">atmospheric</span> model (RegCM3) and a <span class="hlt">regional</span> oceanic model (FVCOM) over the maritime continent</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Climatological high resolution coupled climate model simulations for the maritime continent have been carried out using the <span class="hlt">regional</span> climate model (RegCM) version 3 and the finite volume coastal ocean model (FVCOM) ...</p> <div class="credits"> <p class="dwt_author">Wei, Jun</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">343</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JGRC..118.4600Z"> <span id="translatedtitle"><span class="hlt">Atmospheric</span> forcing intensifies the effects of <span class="hlt">regional</span> ocean warming on reef-scale temperature anomalies during a coral bleaching event</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We investigate how local <span class="hlt">atmospheric</span> conditions and hydrodynamic forcing contributed to local variations in water temperature within a fringing coral reef-lagoon system during the peak of a marine heat wave in 2010-2011 that caused mass coral bleaching across Western Australia. A three-dimensional circulation model <span class="hlt">Regional</span> Ocean Modeling System (ROMS) with a built-in air-sea heat flux exchange module Coupled Ocean <span class="hlt">Atmosphere</span> Experiment (COARE) was coupled with a spectral wave model Simulating Waves Nearshore (SWAN) to resolve the surface heat exchange and wave-driven reef circulation in Coral Bay, Ningaloo Reef. Using realistic oceanic and <span class="hlt">atmospheric</span> forcing, the model predictions were in good agreement with measured time series of water temperature at various locations in the coral reef system during the bleaching event. Through a series of sensitivity analyses, we found that the difference in temperature between the reef and surrounding offshore waters (?T) was predominantly a function of both the daily mean net heat flux (Qnet>¯) and residence time, whereas diurnal variations in reef water temperature were dependent on the diurnal fluctuation in the net heat flux. We found that reef temperatures were substantially higher than offshore in the inner lagoon under normal weather conditions and over the entire reef domain under more extreme weather conditions (0.7°C-1.5°C). Although these temperature elevations were still less than that caused by the <span class="hlt">regional</span> ocean warming (2°C-3°C), the arrival of peak seasonal temperatures in the summer of 2010-2011 (when net <span class="hlt">atmospheric</span> heat fluxes were positive and abnormally high) caused substantially higher thermal stresses than would have otherwise occurred if offshore temperatures had reached their normal seasonal maxima in autumn (when net <span class="hlt">atmospheric</span> heat fluxes were negative or cooling). Therefore, the degree heating weeks calculated based on offshore temperature substantially underestimated the thermal stresses experienced by the reef in the period leading up to the observed bleaching event (3 versus 11°C-weeks).</p> <div class="credits"> <p class="dwt_author">Zhang, Zhenlin; Falter, James; Lowe, Ryan; Ivey, Greg; McCulloch, Malcolm</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">344</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/940218"> <span id="translatedtitle">Studies of <span class="hlt">regional</span>-scale climate variability and change: Hidden Markov models and coupled ocean-<span class="hlt">atmosphere</span> modes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">In this project we developed further a twin approach to the study of <span class="hlt">regional</span>-scale climate variability and change. The two approaches involved probabilistic network (PN) models (sometimes called dynamic Bayesian networks) and intermediate-complexity coupled ocean-<span class="hlt">atmosphere</span> models (ICMs). We thus made progress in identifying the predictable modes of climate variability and investigating their impacts on the <span class="hlt">regional</span> scale. In previous work sponsored by DOEâÂ?Â?s Climate Change Prediction Program (CCPP), we had developed a family of PNs (similar to Hidden Markov Models) to simulate historical records of daily rainfall, and used them to downscale seasonal predictions of general circulation models (GCMs). Using an idealized <span class="hlt">atmospheric</span> model, we had established a novel mechanism through which ocean-induced sea-surface temperature (SST) anomalies might inï¬Â?uence large-scale <span class="hlt">atmospheric</span> circulation patterns on interannual and longer time scales; similar patterns were found in a hybrid coupled oceanâÂ?Â?<span class="hlt">atmosphere</span>âÂ?Â?sea-ice model. In this continuation project, we built on these ICM results and PN model development to address prediction of rainfall and temperature statistics at the local scale, associated with global climate variability and change, and to investigate the impact of the latter on coupled oceanâÂ?Â?<span class="hlt">atmosphere</span> modes. Our main project results consist of extensive further development of the hidden Markov models for rainfall simulation and downscaling together with the development of associated software; new intermediate coupled models; a new methodology of inverse modeling for linking ICMs with observations and GCM simulations, called empirical mode reduction (EMR); and observational studies of decadal and multi-decadal natural climate variability, informed by ICM simulations. A particularly timely by-product of this work is an extensive study of clustering of cyclone tracks in the extratropical Atlantic and the western Tropical Pacific, with potential applications to predicting landfall.</p> <div class="credits"> <p class="dwt_author">M. Ghil (UCLA), PI; S. Kravtsov (UWM); A. W. Robertson (IRI); P. Smyth (UCI)</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-10-14</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">345</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007AGUSMGP41A..04V"> <span id="translatedtitle">The impact of the October-November 2003 intense solar storm events on the <span class="hlt">atmospheric</span> circulation in the Pacific Southern Hemisphere Magnetic Anomaly <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Evidences of the solar activity modulation of the Earth's climate have been observed on different time scales. The main solar activity mechanisms to control climate proposed to explain these observations are: (1) the variability of the total solar irradiance causing a change in the total energy input to the earth's <span class="hlt">atmosphere</span> and consequent warming/cooling; (2) the variability of the solar ultraviolet emission and its effects on the stratospheric ozone and thermal structure; (3) the cosmic rays effects on the cloud coverage; and (4) high energy particle precipitation effects on mesospheric and stratospheric ozone in the auroral and/or southern hemisphere magnetic anomaly <span class="hlt">regions</span> during solar storm events. It is conceivable that these mechanisms contribute to varying extends on different <span class="hlt">regions</span>. However, the precise roles of each process during extreme solar events have not yet been investigated. Here we show that the unusual <span class="hlt">atmospheric</span> circulation conditions over the southern Pacific and Atlantic oceans, and South America on late October and early November 2003 could be related to the large solar storm events, the Halloween events. We observed the development of anti-cyclones in the South Pacific after the onset of the main proton events. We observed also changes in the position and intensity of the Intertropical Convergence Zone and in the South Pacific Convergence zone. This result reveals that effects on the <span class="hlt">atmospheric</span> conditions, including cloud coverage and radiative flux in the <span class="hlt">atmosphere</span>, in the southern hemisphere magnetic anomaly <span class="hlt">region</span> could be observed during extreme solar conditions. Previous studies suggested that the <span class="hlt">influence</span> of solar activity on climate could be observed on decadal to millennia time scales. Our results demonstrate that the variability of the solar activity could have impact on southern hemisphere weather and climatic conditions. We anticipate our analysis to be a starting point for more sophisticated weather and climatic models. For example, the predictability of El Niño events could be tested, including its worldwide effects, based on space weather processes. Furthermore, the increase of the southern hemisphere temperature could be investigated based on changes of the Earth's magnetic field configuration.</p> <div class="credits"> <p class="dwt_author">Vieira, L. A.; da Silva, L. A.; Guarnieri, F.; Echer, E.; Prestes, A.; Dal Lago, A.; da Silva, M. R.; Schuch, N.; Wrasse, C. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">346</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.5227D"> <span id="translatedtitle">Non-linear Ice Sheet <span class="hlt">influence</span> during deglaciation and its impact on the evolution of <span class="hlt">atmospheric</span> teleconnection patterns</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">During present conditions <span class="hlt">atmospheric</span> teleconnections such as the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) have a major impact on Northern Hemispheric climate. However, the Early Holocene is characterized by the presence and melting of the Laurentide Ice Sheet (LIS) leading to a different background climate in comparison to today. Here we investigate the climate evolution during the early (9 ka BP, including LIS and melt water), mid (6 ka BP) and late Holocene (pre-industrial conditions) focussing on the mechanisms and feedbacks during deglaciation by applying the state-of-the-art earth system model COSMOS. A special interest is set on the evolution of <span class="hlt">atmospheric</span> teleconnection patterns such as the AO/NAO and the Atlantic Multidecadal Oscillation (AMO) that have a major <span class="hlt">influence</span> on North Atlantic/European climate. The evolution and relative importance of these oscillations throughout the Holocene, however, is still largely unknown. We demonstrate that North Atlantic/European climate is affected by a shift from a more ocean-ice-dominated climate during approx. 9 ka towards a more <span class="hlt">atmosphere</span>-dominated one during the mid to late Holocene. To isolate the contributions of the presence of the LIS and the melt water we run four different model simulations for the early Holocene sensitivity study (a standard configuration only forced with green house gases and orbital parameters, one with the additional LIS topography, one with a melt water flux of 0.09 Sv, and a fourth that combines all the external forcings). The model results show that the <span class="hlt">influence</span> of the LIS and its melt water contribution lead to a strong non-linear cooling of surface air temperatures during deglaciation. This synergetic <span class="hlt">influence</span> of the Laurentide Ice Sheet strengthens the effect of melting on ocean circulation during the early Holocene. The severe colder background climate during deglaciation leads to a more vulnerable ocean circulation in terms of the Atlantic Meridional Overturning Circulation. Changes of this circulation are known to affect the <span class="hlt">atmosphere</span> as well via mechanisms like the AMO. The corresponding sea level pressure pattern is an <span class="hlt">atmospheric</span> response to oceanic thermal forcing, which results from variations of the thermohaline circulation. The AMO has a potential to <span class="hlt">influence</span> the shape of the subtropical high and to shift AO/NAO pressure centres towards easterly and north-easterly directions during the early Holocene. This non-stationary behaviour of the AO/NAO due to deglaciation processes is also demonstrated by a novel set of North Atlantic/European speleothem records that show an active AO/NAO all over the Holocene.</p> <div class="credits"> <p class="dwt_author">Dietrich, Stephan; Wassenburg, Jasper; Wei, Wei; Lohmann, Gerrit; Jens, Fohlmeister; Adrian, Immenhauser</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">347</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.C13A0655C"> <span id="translatedtitle"><span class="hlt">Influence</span> of elevated NOx levels on the oxidation capacity of the <span class="hlt">atmospheric</span> boundary layer in Barrow, Alaska</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The main <span class="hlt">atmospheric</span> NOx source in the Arctic is irradiated snow surfaces. However, there are local anthropogenic sources that can significantly enhance the local <span class="hlt">atmospheric</span> NOx concentrations and also impact snow photochemistry through deposition of reaction products. This <span class="hlt">influence</span> is expected to increase with increasing NOx sources in the Arctic and has poorly understood impacts on boundary layer halogen chemistry. In this study we used a zero-dimensional box model generated using FACSIMILE to investigate the <span class="hlt">influence</span> of NOx on halogen and HOx chemistry in the Arctic. Trace gas measurements conducted during the 2009 OASIS (Ocean-<span class="hlt">Atmospheric</span>-Snowpack-Sea Ice) field campaign at Barrow, AK, were used to constrain various model inputs. In this presentation, we present the results, which generally show that NOx significantly impedes gas-phase radical chemistry, through production of a variety of reservoir species, including HNO3, HO2NO2, PAN, BrNO2 and ClNO2. However, the impact on heterogeneous chemistry is much less well known, and is in need of further study.</p> <div class="credits"> <p class="dwt_author">Custard, K. D.; Stephens, C. R.; Pratt, K.; Shepson, P. B.; Liao, J.; Nenes, A.; Orlando, J. J.; Weinheimer, A. J.; Apel, E. C.; Hall, S. R.; Flocke, F. M.; Mauldin, L.; Hornbrook, R. S.; Weibring, P.; Fried, A.; Sive, B. C.; Knapp, D. J.; Montzka, D.; Cantrell, C. A.; Ullmann, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">348</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1980STIN...8130342G"> <span id="translatedtitle">Study of the <span class="hlt">influence</span> of the <span class="hlt">atmosphere</span> on the performance of an imaging microwave radiometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Errors induced by the intervening <span class="hlt">atmosphere</span> on the determination of ground parameters from a set of radiometers operating in two polarization states and in the frequency range from 5 to 90 GHz were analyzed. The precision with which the <span class="hlt">atmospheric</span> parameters themselves are measurable was studied. Methods for estimating parameters from measurements performed in a noisy environment are discussed. The radiative transfer problem through a scattering medium is reviewed and an approximate scalar form of the radiative equation proposed, valid under the assumption that the depolarizing effect can be neglected. A complete model for the <span class="hlt">atmosphere</span> is discussed, and analytical expressions for the attenuations from <span class="hlt">atmospheric</span> gases, clouds and rain are given for the frequency range of interest. Models for the radiative behavior of sea and sea ice are discussed. Finally the performance of the multichannel radiometer is analyzed for several typical situations.</p> <div class="credits"> <p class="dwt_author">Guissard, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">349</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=186948"> <span id="translatedtitle"><span class="hlt">Influence</span> of Modified <span class="hlt">Atmosphere</span> Storage on Aflatoxin Production in High Moisture Corn</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Samples of freshly harvested corn and remoistened corn were inoculated with Aspergillus flavus and stored for 4 weeks at about 27 C in air and three modified <span class="hlt">atmospheres</span>. Aflatoxins and fat acidity were determined weekly. Corn stored in the modified <span class="hlt">atmospheres</span> did not accumulate over 15 ?g of aflatoxin B1 per kg and 20 ?g of total aflatoxins per kg. Corn from the high CO2 treatment (61.7% CO2, 8.7% O2, and 29.6% N2) was visibly molded at 4 weeks and had a higher fat acidity than the other treatments. In the N2 (99.7% N2 and 0.3% O2) and controlled <span class="hlt">atmosphere</span> (13.5% CO2, 0.5% O2, 84.8% N2) treatments, a fermentation-like odor was detected. When the corn was removed from the modified <span class="hlt">atmospheres</span> it deteriorated rapidly and was soon contaminated with aflatoxins. PMID:803817</p> <div class="credits"> <p class="dwt_author">Wilson, David M.; Jay, Edward</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">350</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009ACPD....924847X"> <span id="translatedtitle">Identification of potential <span class="hlt">regional</span> sources of <span class="hlt">atmospheric</span> total gaseous mercury in Windsor, Ontario, Canada using hybrid receptor modeling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Windsor (Ontario) - the automotive capital of Canada does not have any significant mercury (Hg) sources. However, Windsor experiences trans-boundary air pollution as it is located immediately downwind of industrialized <span class="hlt">regions</span> of the United States of America. A study was conducted in 2007 aimed to identify the potential <span class="hlt">regional</span> sources of total gaseous mercury (TGM) and investigate the effects of <span class="hlt">regional</span> sources and other factors on seasonal variability of TGM concentrations in Windsor. TGM concentration was measured at the University of Windsor campus using a Tekran® 2537A Hg vapour analyzer. An annual mean of 2.02±1.63 ng/m3 was observed in 2007. The average TGM concentration was high in the summer (2.48 ng/m3) and winter (2.17 ng/m3), compared to spring (1.88 ng/m3) and fall (1.76 ng/m3). Hybrid receptor modeling potential source contribution function (PSCF) was used by incorporating 72-h backward trajectories and measurements of TGM in Windsor. The results of PSCF were analyzed in conjunction with the Hg emissions inventory of North America (by state/province) to identify <span class="hlt">regions</span> affecting Windsor. In addition to annual modeling, seasonal PSCF modeling was also conducted. The potential source <span class="hlt">region</span> was identified between 24-61° N and 51-143° W. Annual PSCF modeling identified major sources southwest of Windsor, stretching from Ohio to Texas. The emissions inventory also supported the findings, as Hg emissions were high in those <span class="hlt">regions</span>. Results of seasonal PSCF modeling were analyzed to find the combined effects of <span class="hlt">regional</span> sources, meteorological conditions, and surface reemissions, on intra-annual variability of Hg concentrations. It was found that the summer and winter highs of <span class="hlt">atmospheric</span> Hg can be attributed to areas where large numbers of coal fired power plants are located in the USA. Weak <span class="hlt">atmospheric</span> dispersion due to low winds and high reemission from surfaces due to higher temperatures contributed to high concentrations in the summer. In the winter, the <span class="hlt">atmospheric</span> removal of Hg was slow, but strong winds led to more dispersion, resulting in lower concentrations than the summer. Future studies could use smaller grid sizes and refined emission inventories, for more accurate analysis of source-receptor relationship of <span class="hlt">atmospheric</span> Hg. Abbreviations of states/provinces: Alabama (AL), Arkansas (AR), British Columbia (BC), Georgia (GA), Iowa (IA), Illinois (IL), Indiana (IN), Kentucky (KY), Louisiana (LA), Manitoba (MB), Michigan (MI), Minnesota (MN), Mississippi (MS), Missouri (MO), Newfoundland and Labrador (NL), Ohio (OH), Ontario (ON), Oregon (OR), Pennsylvania (PA), Tennessee (TN), Texas (TX), West Virginia (WV), Wisconsin (WI).</p> <div class="credits"> <p class="dwt_author">Xu, X.; Akhtar, U. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">351</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ArMiS..59..897B"> <span id="translatedtitle">The <span class="hlt">Influence</span> of Shale Rock Fracturing Equipment Operation on <span class="hlt">Atmospheric</span> Air Quality</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The hydraulic fracturing jobs performed on shale rocks are connected with <span class="hlt">atmospheric</span> emissions of dusts and exhaust gases from high-power motors supplying pump aggregates used for fracturing operations and from other technological devices. The total power of motors driving technological systems depends on the specific character of deposit and well and may range between a dozen to tens of thousands kW. An exemplary set of technological systems used for frac jobs is presented in figure 1. The following substances are emitted to the <span class="hlt">atmosphere</span> during engine operation, e.g. nitrogen oxides (NOx), sulfur dioxide (SO2), carbon oxide (CO), dust PM10, ammonia, benzo(a)pyrene (B(a)P), benzene, toluene, xylene, formaldehyde, acetaldehyde, acrolein. As a consequence admissible concentrations of these substances in air can be exceeded. The <span class="hlt">influence</span> of dust and gaseous emissions accompanying shale rock fracturing jobs is addressed in this paper. Model analyses were performed. An exemplary model of a process used for simulating propagation of <span class="hlt">atmospheric</span> emissions in a specified calculation area (1,150 m × 1,150 m) were based on the analysis of hydraulic fracturing jobs performed in wells in Poland and abroad. For making calculations more actual, the model was located in the Gda?sk area and was ascribed its typical meteorological and orographic parameters. In the center of this area a rig site 150 m x 150 m was distinguished. The emission field was generated by 12 high-power engines supplying pump aggregates, 1680 kW each. The time of work of particular engines was established for 52 hrs (13 frac jobs, each lasting 4 hrs). It was assumed that all engines will operate simultaneously and using 100% of their power. Attention was paid to the correct modelling of the real emission field. Technical parameters of motors and the applied fuels were characterized. Emission indices were worked out by, e.g. U.S. Environmental Protection Agency or European Environment Agency. The calculations of air pollutions from analyzed motors were performed with a mathematical modelling method using Gaussian plum. The results of calculations could be used for evaluating spatial distribution of maximum 1 hour concentrations (S1), incidence of exceeding admissible 1 hour concentration values (P(D1)), percentile 99.8 or 99.726 from 1 hour concentrations and average concentrations (Sa) for selected most important for the air quality contaminants, i.e. NOx (as NO2), SO2, CO, PM10, benzo(a)pyrene, benzene, toluene, xylene, formaldehyde, acetaldehyde and acrolein. The results of calculated air concentrations of selected substances on the rig border are listed in table 9, whereas spatial distributions of NOx and PM10 concentrations in figures 3 to 8. The analysis of the obtained results did not reveal cases of exceeding Polish emission standards. However, nitrogen oxide (NOx) or dust PM10 can be expected to exceed these values, e.g. in a situation when the total power installed in motors driving technological systems in the course of hydraulic fracking will be higher than assumed in the analyses. The results of calculations show to a significant impact of nitrogen oxides (NOx) and dust PM10 emissions on air quality. The risk that emission standards are exceeded beyond the rig area is conditioned both by technological factors (total power of operating motors, parameters of combusted fuel, reduced emission technologies applied to engines, duration of frac jobs, etc.) and a number of external factors, e.g. meteorological and orographic factors or high level of emitted substances in air within the rig area. Proces hydraulicznego szczelinowania ska? ?upkowych wi??e si? z emisj? do powietrza zanieczyszcze? py?owo-gazowych z silników wysokopr??nych du?ej mocy nap?dzaj?cych agregaty pompowe do szczelinowania ska? oraz inne urz?dzenia technologiczne. ??czna moc silników nap?dzaj?cych urz?dzenia technologiczne uzale?niona jest od specyfiki z?o?a oraz specyfiki odwiertu i waha si? od kilkunastu do kilkudziesi?ciu tysi?cy kW. Przyk?adowy zestaw u</p> <div class="credits"> <p class="dwt_author">Bogacki, Marek; Macuda, Jan</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">352</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008AGUFM.B53E..03H"> <span id="translatedtitle"><span class="hlt">Influences</span> of Forest Tree Species and Early Spring Temperature on Surface-<span class="hlt">Atmosphere</span> Transfers of Water and Carbon in the Northeastern U.S.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Influences</span> of Forest Tree Species and Early Spring Temperature on Surface-<span class="hlt">Atmosphere</span> Transfers of Water and Carbon in the Northeastern U.S. Julian Hadley, Paul Kuzeja, Safina Singh and Thomas Mulcahy Transfers of water vapor from terrestrial ecosystems to the <span class="hlt">atmosphere</span> affect <span class="hlt">regional</span> hydrology, weather and climate over short time scales, and forest-<span class="hlt">atmosphere</span> CO2 exchange affects global climate over long timescales. To better understand these effects for forests dominated by two very different tree species, we measured forest-<span class="hlt">atmosphere</span> water vapor and CO2 transfers by the eddy flux technique to at two sites in central Massachusetts USA for three years. Average annual evapotranspiration (ET) for a young deciduous forest dominated by red oak (Quercus rubra L., the most abundant tree species in the area), was about 430 mm or 25 percent greater than for a coniferous forest dominated by 100 to 230 year old eastern hemlock (Tsuga canadensis L.). The difference in ET was most pronounced in July and August when the deciduous forest lost about 50 percent more water by ET in the average year (192 mm for oak forest versus 130 mm for hemlock). These data indicate that if deciduous trees with similar physiology to red oak replace hemlocks, summertime ET will increase while summer streamflow, soil water content and the extent of year- round wetlands will decrease. Increased summertime ET should also lead to slightly higher <span class="hlt">regional</span> <span class="hlt">atmospheric</span> humidity and precipitation. Hemlock-to-deciduous forest conversion has occurred from North Carolina to southern New England and is continuing northward as a lethal insect pest, the hemlock woolly adelgid (Adelges tsugae Annand) continues to kill hemlocks. Average annual carbon storage for the old hemlock forest in our study was about 3.3 Mg C/ha, nearly equal to the average for the deciduous forest, 3.5 Mg C/ha. This calls into question ecological theory that predicts large declines in the rate of carbon uptake for old forests, and indicates that annual carbon storage will not necessarily increase over the long term after hemlock trees are killed by the hemlock woolly adelgid and replaced by deciduous species. Maximum monthly carbon storage in the hemlock forest occurred in spring (April and May) and was enhanced by early soil thawing and cessation of nighttime frost. This pattern is probably common to many evergreen conifers in the northeastern U.S., so climate warming that includes an earlier end to freezing temperatures in spring should increase C storage by conifer forests in the northeastern U.S. - unless this effect is canceled out by reduced C uptake or enhanced C loss due to changes in summer and fall climate.</p> <div class="credits"> <p class="dwt_author">Hadley, J. L.; Kuzeja, P.; Mulcahy, T.; Singh, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">353</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008ACPD....813125R"> <span id="translatedtitle">In situ measurements of speciated <span class="hlt">atmospheric</span> mercury and the identification of source <span class="hlt">regions</span> in the Mexico City Metropolitan Area</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In order to expand the currently limited understanding of <span class="hlt">atmospheric</span> mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of <span class="hlt">atmospheric</span> mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March, 2006. Numerous short-lived increases in particulate mercury (PHg) and reactive gaseous mercury (RGM) concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM) concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows: i) Urban site: PHg=187±300 pg m-3, RGM=62±64 pg m-3, GEM=7.2±4.8 ng m-3. ii) Rural site: GEM=5.0±2.8 ng m-3. Several source <span class="hlt">regions</span> of <span class="hlt">atmospheric</span> mercury to the urban and rural sites were determined using Concentration Field Analysis, in which <span class="hlt">atmospheric</span> mercury measurements were combined with back trajectory data to determine source <span class="hlt">regions</span>. Only some source <span class="hlt">regions</span> correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM), and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg and RGM) were not found to correlate with biomass burning at either of the measurement sites.</p> <div class="credits"> <p class="dwt_author">Rutter, A. P.; Snyder, D. C.; Stone, E. A.; Schauer, J. J.; Gonzalez-Abraham, R.; Molina, L. T.; Márquez, C.; Cárdenas, B.; de Foy, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">354</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009ACP.....9..207R"> <span id="translatedtitle">In situ measurements of speciated <span class="hlt">atmospheric</span> mercury and the identification of source <span class="hlt">regions</span> in the Mexico City Metropolitan Area</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In order to expand the currently limited understanding of <span class="hlt">atmospheric</span> mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of <span class="hlt">atmospheric</span> mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March 2006. Numerous short-lived increases in particulate mercury (PHg) and reactive gaseous mercury (RGM) concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM) concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows: i) urban site; PHg=187±300 pg m-3, RGM=62±64 pg m-3, GEM=7.2±4.8 ng m-3, and; ii) rural site; GEM=5.0±2.8 ng m-3. Several source <span class="hlt">regions</span> of <span class="hlt">atmospheric</span> mercury to the urban and rural sites were determined using Concentration Field Analysis, in which <span class="hlt">atmospheric</span> mercury measurements were combined with back trajectory data to determine source <span class="hlt">regions</span>. Only some source <span class="hlt">regions</span> correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM), and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg+RGM) were not found to correlate with biomass burning at either of the measurement sites.</p> <div class="credits"> <p class="dwt_author">Rutter, A. P.; Snyder, D. C.; Stone, E. A.; Schauer, J. J.; Gonzalez-Abraham, R.; Molina, L. T.; Márquez, C.; Cárdenas, B.; de Foy, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">355</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/43171513"> <span id="translatedtitle">Ice in the environment: connections to <span class="hlt">atmospheric</span> chemistry</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ice in the environment, whether in the form of ice particles in clouds or sea ice and snow at the Earth's surface, has a profound <span class="hlt">influence</span> on <span class="hlt">atmospheric</span> composition and climate. The interaction of trace <span class="hlt">atmospheric</span> gases with snow and sea ice surfaces largely controls <span class="hlt">atmospheric</span> composition in polar <span class="hlt">regions</span>. The heterogeneous chemistry of ice particles in clouds also plays</p> <div class="credits"> <p class="dwt_author">V Faye McNeill; Meredith G Hastings</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">356</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009ThApC..96...57C"> <span id="translatedtitle">Changes of <span class="hlt">atmospheric</span> circulation in central Europe and their <span class="hlt">influence</span> on climatic trends in the Czech Republic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This work deals with the <span class="hlt">influence</span> of changes of <span class="hlt">atmospheric</span> circulation on observed trends of 11 climatic elements at 21 stations in the Czech Republic in the period 1961-1998. <span class="hlt">Atmospheric</span> circulation in central Europe is described by the German (Hess-Brezowsky) and Czech-Slovak (Brádka’s) subjective catalogues of synoptic types. In the study period there is a strong downward trend in the occurrence of anticyclonic types in Brádka’s catalogue in all seasons, this trend being most prominent in autumn. Westerly and northwesterly types become more frequent in autumn and winter, less frequent in spring and summer under both classifications. In the Hess-Brezowsky catalogue, the occurrence of anticyclonic types increases in winter, spring, and summer. To assess the effect of circulation changes on observed climate trends we have used the method of “hypothetical” seasonal trends that are calculated from a daily series, constructed by assigning the long-term monthly average of the given climatic element under a specific circulation type to each day classified with this type. The ratio of these circulation-conditioned trends and observed seasonal trends shows that changes in <span class="hlt">atmospheric</span> circulation are the primary cause of massive winter warming and autumn cooling, which is connected with increasing precipitation and humidity. Summer climate trends are unrelated to changes in <span class="hlt">atmospheric</span> circulation. Simultaneous use of more circulation classifications for the detection of climatic changes is highly recommended, as the long-term circulation trends depend on the catalogue applied.</p> <div class="credits"> <p class="dwt_author">Cahynová, Monika; Huth, Radan</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">357</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/25339532"> <span id="translatedtitle">The <span class="hlt">influence</span> of <span class="hlt">atmospheric</span> conditions on the leakage current of ceramic insulators on the Colombian Caribbean coast.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The contamination of electrical insulators is one of the major contributors to the risk of operation outages in electrical substations, especially in coastal zones with high salinity levels and <span class="hlt">atmospheric</span> pollution. By using the measurement of leakage-currents, which is one of the main indicators of contamination in insulators, this work seeks to the determine the correlation with climatic variables, such as ambient temperature, relative humidity, solar irradiance, <span class="hlt">atmospheric</span> pressure and wind speed and direction. The results obtained provide an input to the behaviour of the leakage current under <span class="hlt">atmospheric</span> conditions that are particular to the Caribbean coast of Colombia. Spearman's rank correlation coefficients and principal component analysis are utilised to determine the significant relationships among the different variables under consideration. The necessary information for the study was obtained via historical databases of both <span class="hlt">atmospheric</span> variables and the leakage current measured in over a period of 1 year in a 220-kV potential transformer insulator. We identified the <span class="hlt">influencing</span> factors of temperature, humidity, radiation, wind speed and direction on the magnitude of the leakage current as the most relevant. PMID:25339532</p> <div class="credits"> <p class="dwt_author">Castillo Sierra, Rafael; Oviedo-Trespalacios, Oscar; Candelo, John E; Soto, Jose D</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">358</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.A23B0200B"> <span id="translatedtitle"><span class="hlt">Influence</span> of outflow from the Gulf of Mexico <span class="hlt">region</span> on NMHC composition of the free and upper troposphere over Europe and the North Atlantic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The CARIBIC project (Civil Aircraft for the Regular Investigation of the <span class="hlt">atmosphere</span> Based on an Instrument Container; www.caribic-<span class="hlt">atmospheric</span>.com) involves the deployment of an instrument container equipped to make <span class="hlt">atmospheric</span> measurements from aboard a passenger jet, and has operated since 2005 from aboard a Lufthansa Airbus 340-600. Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. A suite of 20 non-methane hydrocarbons (NMHCs) are measured from the whole air samples, along with greenhouse gas and halocarbon measurements. As all flights originate in and return to Frankfurt, Germany, the free and upper troposphere (FT/UT) over Europe and the North Atlantic are probed on nearly every flight, and the composition was found to be strongly <span class="hlt">influenced</span> by air masses from the Gulf of Mexico <span class="hlt">region</span>. Over 75% of air samples collected during flight had backwards trajectories which passed over the <span class="hlt">region</span>, and nearly half of these had passed through the lower troposphere and boundary layer, affording CARIBIC a "bird's-eye view" of emissions from the Gulf <span class="hlt">region</span>. Measurements of NMHCs, and also methane, show distinct fossil fuel extraction signatures for Gulf <span class="hlt">region</span> outflow, namely relatively large enhancements in C2-C4 alkanes coupled with unique ratios between species. Here we discuss the impact of these emissions and their subsequent chemical transformations on FT/UT composition. We also investigate the possible <span class="hlt">influence</span> of these emissions on the increase in C2-C4 alkanes observed in the FT/UT by CARIBIC over the last 7 years.</p> <div class="credits"> <p class="dwt_author">Baker, A. K.; Schuck, T. J.; Rauthe-Schöch, A.; Brenninkmeijer, C. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">359</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cdsweb.cern.ch/record/1622327"> <span id="translatedtitle">Magnesium in the <span class="hlt">atmosphere</span> of the planet HD209458b: Observations of the thermosphere-exosphere transition <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">We report new near ultraviolet HST/STIS observations of <span class="hlt">atmospheric</span> absorptions during the planetary transit of HD209458b. We detect absorption in atomic magnesium (MgI), while no signal has been detected in the lines of singly ionized magnesium (MgII). We measure the MgI <span class="hlt">atmospheric</span> absorption to be 6.2+/-2.9% in the velocity range from -62 to -19 km/s. The detection of atomic magnesium in the planetary upper <span class="hlt">atmosphere</span> at a distance of several planetary radii gives a first view into the transition <span class="hlt">region</span> between the thermosphere and the exobase, where <span class="hlt">atmospheric</span> escape takes place. We estimate the electronic densities needed to compensate for the photo-ionization by dielectronic recombination of Mg+ to be in the range of 10^8-10^9 cm^{-3}. Our finding is in excellent agreement with model predictions at altitudes of several planetary radii. We observe MgI atoms escaping the planet, with a maximum radial velocity (in the stellar rest frame) of -60 km/s. Because magnesium is much heavier than hydrogen, the es...</p> <div class="credits"> <p class="dwt_author">Vidal-Madjar, A; Bourrier, V; Désert, J -M; Ballester, G; Etangs, A Lecavelier des; Sing, D K; Ehrenreich, D; Ferlet, R; Hébrard, G; McConnell, J C</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">360</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55900929"> <span id="translatedtitle">EDITORIAL: Ice in the environment: connections to <span class="hlt">atmospheric</span> chemistry Ice in the environment: connections to <span class="hlt">atmospheric</span> chemistry</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ice in the environment, whether in the form of ice particles in clouds or sea ice and snow at the Earth's surface, has a profound <span class="hlt">influence</span> on <span class="hlt">atmospheric</span> composition and climate. The interaction of trace <span class="hlt">atmospheric</span> gases with snow and sea ice surfaces largely controls <span class="hlt">atmospheric</span> composition in polar <span class="hlt">regions</span>. The heterogeneous chemistry of ice particles in clouds also plays</p> <div class="credits"> <p class="dwt_author">V. Faye McNeill; Meredith G. Hastings</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a style="font-weight: bold;">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_20");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">361</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.A23I..02S"> <span id="translatedtitle">Possible ENSO <span class="hlt">influence</span> on soil N2O emissions and <span class="hlt">atmospheric</span> N2O mole fractions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">N2O is currently one of the most important ozone-depleting substances, and the third largest anthropogenic-biogenic greenhouse gas. Despite its impact on stratospheric ozone destruction, it is not regulated by the Montreal Protocol, and global observations show that the N2O mole fractions is increasing continuously at a rate of 0.2 to 0.3% per year. Sinks and sources of N2O still have large uncertainties but previous studies have estimated that soil emissions account for approximately 60% of the total emissions. Because the variability in soil emissions could potentially have important implications for <span class="hlt">regional</span> and global climate change, and vice versa, it is essential to better understand the processes and feedbacks associated with soil N2O emissions. To achieve this goal and better quantify global soil N2O emissions, we have included the denitrification-decomposition module (DNDC) into the Community Land Model with coupled Carbon and Nitrogen cycles (CLM-CN) version 3.5. Using four different bias-corrected, reanalysis-based meteorological datasets, we have constructed four global gridded soil N2O emission estimates for the years 1975 through the mid-2000s. We find evidence for a significant El Niño-Southern Oscillation <span class="hlt">influence</span> on soil N2O emissions with reduced emissions in El Niño years and increased emissions in La Niña years in our model. In addition, we use these soil emission (and other source) estimates in a 3-dimensional chemical transport model - the Model for OZone And Related chemical Tracers (MOZART) version 4 - to analyze the impact of this inter-annual variability in soil emissions on simulations of N2O measurements at AGAGE and NOAA-ESRL observational sites.</p> <div class="credits"> <p class="dwt_author">Saikawa, E.; Schlosser, C. A.; Prinn, R. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">362</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AtmEn..78..184C"> <span id="translatedtitle"><span class="hlt">Influence</span> of the Southeast Asian biomass burnings on the <span class="hlt">atmospheric</span> persistent organic pollutants observed at near sources and receptor site</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Persistent organic pollutants (POPs) such as PCDD/Fs, PCBs, PBDD/Fs, PBBs and PBDEs are bio-accumulative, toxic, and susceptible to long-range transport (LRT). This study is the first that comprehensively discusses the long-range <span class="hlt">atmospheric</span> transport behavior of these five groups of POPs. The main goal is to investigate the <span class="hlt">atmospheric</span> characteristics of these POPs at the biomass burning sites of Chiang Mai in Thailand, and Da Nang in Vietnam, as well as the <span class="hlt">influence</span> of the Southeast Asian biomass burnings on the Lulin <span class="hlt">Atmospheric</span> Background Station (LABS) in Taiwan. Biomass burning in Southeast Asia is usually carried to remove the residues of agricultural activities. The ambient air in Da Nang seems to be more seriously affected by the local biomass burnings than that in Chiang Mai. The elevated <span class="hlt">atmospheric</span> brominated POP (PBDD/Fs, PBBs and PBDEs) concentrations in Da Nang were attributed to the biomass burning and viewed as mostly unrelated to the local use of brominated flame retardants. In the spring of 2010, the mean <span class="hlt">atmospheric</span> concentrations in LABS during the first and second Intensive Observation Periods (IOPs) were 0.00428 and 0.00232 pg I-TEQ Nm-3 for PCDD/Fs, 0.000311 and 0.000282 pg WHO-TEQ m-3 for PCBs, 0.000379 and 0.000449 pg TEQ Nm-3 for total PBDD/Fs, 0.0208 and 0.0163 pg Nm-3 for total PBBs, and 109 and 18.2 pg Nm-3 for total PBDEs, respectively. These values represent the above concentrations due to the Southeast Asian biomass burnings. The affected <span class="hlt">atmospheric</span> POP concentrations at the LABS were still at least one order lower than those in other <span class="hlt">atmospheric</span> environments, except for the PBDE concentrations during the first IOP (109 pg Nm-3), which was surprisingly higher than those in Taiwanese metal complex areas (93.9 pg Nm-3) and urban areas (34.7 pg Nm-3). <span class="hlt">Atmospheric</span> POP concentrations do not seem to dramatically decrease during long-range transport, and the reasons for this need to be further investigated.</p> <div class="credits"> <p class="dwt_author">Chang, Shun-Shiang; Lee, Wen-Jhy; Wang, Lin-Chi; Lin, Neng-Huei; Chang-Chien, Guo-Ping</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">363</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ACPD...1423681M"> <span id="translatedtitle">The potential for <span class="hlt">regional</span>-scale bias in top-down CO2 flux estimates due to <span class="hlt">atmospheric</span> transport errors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Estimates of CO2 fluxes that are based on <span class="hlt">atmospheric</span> data rely upon a meteorological model to simulate <span class="hlt">atmospheric</span> CO2 transport. These models provide a quantitative link between surface fluxes of CO2 and <span class="hlt">atmospheric</span> measurements taken downwind. Therefore, any errors in the meteorological model can propagate into <span class="hlt">atmospheric</span> CO2 transport and ultimately bias the estimated CO2 fluxes. These errors, however, have traditionally been difficult to characterize. To examine the effects of CO2 transport errors on estimated CO2 fluxes, we use a global meteorological model-data assimilation system known as "CAM-LETKF" to quantify two aspects of the transport errors: error variances (standard deviations) and temporal error correlations. Furthermore, we develop two case studies. In the first case study, we examine the extent to which CO2 transport uncertainties can bias CO2 flux estimates. In particular, we use a common flux estimate known as CarbonTracker to discover the minimum hypothetical bias that can be detected above the CO2 transport uncertainties. In the second case study, we then investigate which meteorological conditions may contribute to month-long biases in modeled <span class="hlt">atmospheric</span> transport. We estimate 6 hourly CO2 transport uncertainties in the model surface layer that range from 0.15 to 9.6 ppm (standard deviation), depending on location, and we estimate an average error decorrelation time of ∼2.3 days at existing CO2 observation sites. As a consequence of these uncertainties, we find that CarbonTracker CO2 fluxes would need to be biased by at least 29%, on average, before that bias were detectable at existing non-marine <span class="hlt">atmospheric</span> CO2 observation sites. Furthermore, we find that persistent, bias-type errors in <span class="hlt">atmospheric</span> transport are associated with consistent low net radiation, low energy boundary layer conditions. The meteorological model is not necessarily more uncertain in these conditions. Rather, the extent to which meteorological uncertainties manifest as persistent <span class="hlt">atmospheric</span> transport biases appears to depend, at least in part, on the energy and stability of the boundary layer. Existing CO2 flux studies may be more likely to estimate inaccurate <span class="hlt">regional</span> fluxes under those conditions.</p> <div class="credits"> <p class="dwt_author">Miller, S. M.; Fung, I.; Liu, J.; Hayek, M. N.; Andrews, A. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">364</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19760016682&hterms=interdisciplinary+nature+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dinterdisciplinary%2Bnature%2Bwater"> <span id="translatedtitle">Interdisciplinary study of <span class="hlt">atmospheric</span> processes and constituents of the mid-Atlantic coastal <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Progress is reported in the following areas: analysis of the air quality of Plymouth Park, Chesapeake, Virginia; background analysis and impact assessment for the proposed expansion of Busch Gardens; application of remote sensing and <span class="hlt">atmospheric</span> interaction; and biosphere interaction. Plans for further study are included.</p> <div class="credits"> <p class="dwt_author">Kindle, E. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1976-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">365</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950006426&hterms=meteorology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dmeteorology"> <span id="translatedtitle">Satellite estimates of shortwave surface radiation and <span class="hlt">atmospheric</span> meteorology for the BOREAS experiment <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This report provides background data for the Boreal Ecosystem <span class="hlt">Atmosphere</span> Study (BOREAS) sites, including daily, seasonal, interannual, and spatial variability of shortwave (SW) radiation at the Earth's surface. This background data, from the Version 1.1 SW data set, was provided by the Surface Radiation Budget (SRB) Climatology Project established by the World Climate Research Program (WCRP).</p> <div class="credits"> <p class="dwt_author">Moats, C. D.; Whitlock, C. H.; Lecroy, S. R.; Dipasquale, R. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">366</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50722181"> <span id="translatedtitle">Study the effect of ozone layer depletion on aircraft design at <span class="hlt">atmospheric</span> <span class="hlt">region</span> of Pakistan</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ozone is of considerable importance to mankind because of its role as a shield for the biosphere against the Ultraviolet (UV) radiation from the outer space, in particular from the sun. Due to a serious reduction of O3 content in the <span class="hlt">atmosphere</span>, life-forms on the earth are exposed to a new hazard in the form of an increase of harmful</p> <div class="credits"> <p class="dwt_author">M. A. K. Y. Zai; M. R. K. Ansari</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">367</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AtmEn..57...91A"> <span id="translatedtitle">Analysis on source features of halogenated gases at Shangdianzi <span class="hlt">regional</span> <span class="hlt">atmospheric</span> background station</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the study, the five-day back-trajectories collected by Shangdianzi Station were categorized by season, calculated four times a day during the period of 2008-2010, based on the Lagrangian particle integrated trajectory model HYSPLIT, and using the back-trajectory cluster analysis method. Efforts were made to understand the impacts of different trajectories on the concentration of halogenated gases over the site of Shangdianzi (SDZ) in different seasons, in line with the in-site concentration measurements of halogenated gases, including the 8 species of CFC-11, CFC-12, CCL4, CHCL3, CH3Br, SF6, H-1301, and HCFC-22. Meanwhile, the wind data collected by the same station and the concentration observed during the same period were employed to calculate the loadings of CFC-11, CFC-12, CCL4, CHCL3, CH3Br, SF6, H-1301, and HCFC-22, respectively. The result of back-trajectory cluster analysis suggests that air masses from southeast and southwest accounting for a large proportion of local air masses at SDZ always move slowly within the bottom boundary layer, which is beneficial for the accumulation of pollutants within the boundary layer and leads to the highest mean concentrations of halocarbons among all the clusters. Conversely, the mean concentration of halocarbons corresponding to the fast-moving northwest air masses at high altitude is found to have unanimously low values. The analysis of the concentration loadings proves that WSW and SW are the directions for the maximum concentration loading of all halogenated species, whereas NNW, NNE, NE and ENE are the directions for the minimum concentration loading. We also find that the sector in SW-S-SE is the high concentration loading part, while the sector in NW-N-NE is the low concentration part. The trajectory cluster analysis and concentration loading results indicate that the SE-S-SW towards SDZ is the high pollution source direction for the halogenated species mentioned above, which reflects the <span class="hlt">influence</span> of human activities on the air pollutant transportation at SDZ in a <span class="hlt">regional</span> scale, while NW-N-NE represents the clean direction of the station.</p> <div class="credits"> <p class="dwt_author">An, Xingqin; Zhou, Lingxi; Yao, Bo; Xu, Lin; Ma, Lin</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">368</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..12.4911B"> <span id="translatedtitle">Investigation of Health Risks and Their Prevention in the Rapid Climate Changes and the Rise of Pollution of the <span class="hlt">Atmosphere</span> in the Mountain <span class="hlt">Region</span> of the North Caucasus</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The current global climate change is determined by changes in the structure of weather conditions, whose impact on the health of various <span class="hlt">regions</span> of the planet has not been studied sufficiently. To study this effect on the low-altitude mountains resort of Kislovodsk (southern Russia) multi-factor assessment of the impact of the environment on human health is carried out. There were taking in account <span class="hlt">atmosphere</span> condition, <span class="hlt">atmospheric</span> aerosol pollution relationship with <span class="hlt">atmospheric</span> circulation, the level of pollution matching with different types of weather, and, on the base of analysis of meteopathic reactions (MPR), the extent of their biotropism was revealed. Two sides of weather-climatic <span class="hlt">influences</span> - specific and nonspecific - are interconnected. They manifest themselves differently in humans with different levels of regulation of vital activity and the adaptive capacity of the organism to the complex environmental effects. This complicates the precise physiological basis of quantitative criteria for the prediction of "biotropic" (adverse) weathers. Nevertheless, clinical observations have shown the existence of the "limiting" physiological bound on the size of medical-meteorological modules (MMM). The reactions of the organism to unfavorable weather factors on the results of a questionnaire monitoring surveillance of patients treated in clinics of Federal State Institution "Pyatigorsk State Research Institute of Curortology, FMBA of Russia" (PSRIC), in comparison with clinical data, have identified various MPR of the organism, the clinical manifestation of which depends on age, sex of the patient, the availability of principal and attendant pathology, reactivity, etc. Analysis of the results of clinical observation, cases of medical aid appealability to the station an ambulance at the sudden ill health, as well as the uptake of advice of sick people among immigrants during their short stay at the resort, and the local population, allowed the first approximation to clarify the criteria for "pathogenicity" of various weather conditions and the factors of air pollution. These criteria were put in a new technology of the Medical Weather Forecast (MWF). In this technology it is proposed to use the integrated Weather Pathogenicity Index (WPI), which is calculated as a weighted average of biotropism indices of various MMM, which include: the dynamics and day to day variability of temperature, pressure and humidity, wind speed, weight content of oxygen and natural air ions in the surface <span class="hlt">atmosphere</span>, cloudiness, <span class="hlt">atmospheric</span> phenomena, geomagnetic activity, the ultraviolet index (by UVB solar radiation), the integrated illumination by the sun, the heat conditions of the human. For each of the MMM the five physiological grades of the effects of weather on human adaptation to weather of magnitude and dynamics of WPI are marked out: indifferent, weak, moderate, harsh and overly harsh, according to which the degree of "pathogenicity" of the weather is estimating. Pathogenicity is indicated by quantitative number of medical types of weather (I - a very good weather, II - good weather, III - adverse weather, and IV - a particularly adverse weather). According to the forms of the pressure relief on the sea level, 850 hPa, and 500 hPa, the nature of <span class="hlt">atmospheric</span> stratification and the presence of <span class="hlt">atmospheric</span> fronts in the medical types of weather the type of <span class="hlt">atmospheric</span> circulation is evaluating (anticyclonic - "A", cyclonic - "B", frontal - "C"), which defines a subtype of weather and the possible nature of meteopathia (hypotensive, hypoxic, spastic, etc.). Innovations of the new technology are associated with the introduction of a methodology for the preparation of MWF the modified classifiers to determine the gradation of biotropism degree for various MMM, confirmed by the results of comprehensive empirical medical and climatic studies using dynamic and synoptic weather forecasting making by Hydrometeocenter of Russia and forecast of <span class="hlt">atmospheric</span> pollution </p> <div class="credits"> <p class="dwt_author">Babyakin, Alexander; Polozkov, Igor; Golitsyn, Georgy; Efimenko, Natalia; Zherlitsina, Liubov; Povolotskaya, Nina; Senik, Irina; Chalaya, Elena; Artamonova, Maria; Pogarski, Fedor</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">369</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/6344084"> <span id="translatedtitle"><span class="hlt">Influences</span> of <span class="hlt">atmospheric</span> conditions and air mass on the ratio of ultraviolet to total solar radiation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The technology to detoxify hazardous wastes using ultraviolet (UV) solar radiation is being investigated by the DOE/SERI Solar Thermal Technology Program. One of the elements of the technology evaluation is the assessment and characterization of UV solar radiation resources available for detoxification processes. This report describes the major <span class="hlt">atmospheric</span> variables that determine the amount of UV solar radiation at the earth's surface, and how the ratio of UV-to-total solar radiation varies with <span class="hlt">atmospheric</span> conditions. These ratios are calculated from broadband and spectral solar radiation measurements acquired at SERI, and obtained from the literature on modeled and measured UV solar radiation. The following sections discuss the <span class="hlt">atmospheric</span> effects on UV solar radiation and provide UV-to-total solar radiation ratios from published studies, as well as measured values from SERI's data. A summary and conclusions are also given.</p> <div class="credits"> <p class="dwt_author">Riordan, C.J.; Hulstrom, R.L.; Myers, D.R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">370</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006GeoRL..3313704A"> <span id="translatedtitle"><span class="hlt">Influence</span> of marine denitrification on <span class="hlt">atmospheric</span> N2O variability during the Holocene</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Oceanic denitrification centers are thought to be important marine sources for <span class="hlt">atmospheric</span> N2O. To consider Holocene variability in this source, we reconstruct the Holocene paleo-denitrification history of the Peru margin, a major marine denitrification center, using high-resolution sedimentary ?15N data. This record along with a contemporaneous one from the western Arabian Sea (Altabet et al., 2002) shows similarities with the recently available high-resolution <span class="hlt">atmospheric</span> N2O record (Flückiger et al., 2002). While the role of terrestrial processes in the observed N2O changes remains uncertain, these results suggest that variability in marine denitrification in major upwelling centers such as the Peru margin and the Arabian Sea contributed significantly to <span class="hlt">atmospheric</span> N2O evolution during the Holocene.</p> <div class="credits"> <p class="dwt_author">Agnihotri, Rajesh; Altabet, Mark A.; Herbert, T. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">371</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/41182455"> <span id="translatedtitle">Semidiurnal and longer period stability cycles in the Liverpool Bay <span class="hlt">region</span> of freshwater <span class="hlt">influence</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Detailed observations from a 12.5 h anchor station and a 45 day mooring deployment in the Liverpool Bay <span class="hlt">region</span> of freshwater <span class="hlt">influence</span> are presented. The anchor station data, showing vertical and temporal variations of current, density and gradient Richardson number, demonstrate a semi-diurnal stratification cycle driven by tidal straining of a freshwater-induced horizontal density gradient. The current meter mooring observations</p> <div class="credits"> <p class="dwt_author">Jonathan Sharples; John H. Simpson</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">372</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008EnGeo..54..391K"> <span id="translatedtitle">Environmental effect and genetic <span class="hlt">influence</span>: a <span class="hlt">regional</span> cancer predisposition survey in the Zonguldak <span class="hlt">region</span> of Northwest Turkey</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak <span class="hlt">region</span> of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe-Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the <span class="hlt">region</span> strongly suggested an environmental effect and a genetic <span class="hlt">influence</span> on the increased cancer incidence in the <span class="hlt">region</span>. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the <span class="hlt">region</span>.</p> <div class="credits"> <p class="dwt_author">Kadir, Selahattin; Önen-Hall, A. Piril; Aydin, S. Nihal; Yakicier, Cengiz; Akarsu, Nurten; Tuncer, Murat</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">373</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007PhDT.......126P"> <span id="translatedtitle">Trans-Pacific and <span class="hlt">regional</span> <span class="hlt">atmospheric</span> transport of anthropogenic semivolatile organic compounds in the Western United States</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">atmospheric</span> transport of anthropogenic semivolatile organic compounds (SOCs) from Asian sources to the Western U.S. was investigated. In addition, the SOC extraction method was optimized. Hansen solubility parameter plots were used to aid in the pressurized liquid extraction (PLE) solvent selection of air sampling media in order to minimize polymeric matrix interferences. To estimate the emissions of anthropogenic semivolatile organic compounds (SOCs) from East Asia and to identify unique SOC molecular markers in Asian air masses, air samples were collected on the island of Okinawa, Japan in Spring 2004. Elevated concentrations of hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and particulate-phase polycyclic aromatic hydrocarbons (PAHs) were attributed to air masses from China. A large proportion of the variation in the current use pesticides, gas-phase PAHs, and polychlorinated biphenyl (PCB) concentrations was explained by meteorology. Using measured PAH, carbon monoxide (CO), and black carbon concentrations and estimated CO and black carbon emission inventories, the emission of 6 carcinogenic particulate-phase PAHs were estimated to be 1518-4179 metric tons/year for all of Asia and 778-1728 metric tons/year for only China. <span class="hlt">Atmospheric</span> measurements of anthropogenic SOCs were made at Mt. Bachelor Observatory (MBO), located in Oregon's Cascade Range. PAH concentrations at MBO increased with the percentage of air mass time in Asia and, in conjunction with other data, provided strong evidence that particulate-phase PAHs are emitted from Asia and undergo trans-Pacific <span class="hlt">atmospheric</span> transport to North America. Enhanced HCB, alpha-HCH, and gamma-HCH concentrations also occurred during trans-Pacific <span class="hlt">atmospheric</span> transport, compared with <span class="hlt">regional</span> (Western U.S.) air masses during similar time periods. Gas-phase PAH and fluorotelomer alcohol (FTOH) concentrations significantly increased with the percentage of air mass time in California's urban areas, while retene and PCB concentrations increased with the percentage of air mass time in Oregon and during <span class="hlt">regional</span> fire events. <span class="hlt">Regional</span> <span class="hlt">atmospheric</span> transport in the Western U.S. also resulted in enhanced gamma-HCH, dacthal, endosulfan, metribuzin, triallate, trifluralin, and chlorpyrifos concentrations, with episodic concentration enhancements during spring application periods. Elevated SigmaPCB, Sigmachlordane, HCHs, HCB, and trifuralin concentrations were also associated with fires, which may be due to volatization of pesticides deposited to soils and vegetation.</p> <div class="credits"> <p class="dwt_author">Primbs, Toby</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">374</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/85974"> <span id="translatedtitle">Deposition and transport of <span class="hlt">atmospheric</span> mercury and other HAPS in the Great Lakes <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">To investigate the levels and <span class="hlt">atmospheric</span> transport of hazardous air pollutants (HAPS) a network of event precipitation and ambient monitoring sites was established in Michigan. Measurements of vapor and particulate mercury, trace elements, as well as a number of organochlorine compounds (OCs) including PAHs, PCBs, and selected pesticides were made at four locations in Michigan. Measurements performed in the network from 1992--1994 are discussed together with meteorological data gathered concurrently. Seasonal variations in the levels and deposition of mercury and other compounds are discussed in relation to their sources and dominant transport corridors. The transport of HAPs into and out of Michigan is investigated using calculated air mass trajectories and associated meteorological parameters. The relationship between <span class="hlt">atmospheric</span> mercury, other trace metals, and OCs will be discussed. The paper will discuss this unique data base in a comprehensive way for the first time.</p> <div class="credits"> <p class="dwt_author">Keeler, G.J.; Hoyer, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-12-31</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">375</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/40126514"> <span id="translatedtitle"><span class="hlt">Regional</span> sea level changes projected by the NASA\\/GISS <span class="hlt">Atmosphere</span>-Ocean Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Sea level has been rising for the past century, and coastal residents of the Earth will want to understand and predict future\\u000a sea level changes. In this study we present sea level changes from new simulations of the Goddard Institute for Space Studies\\u000a (GISS) global <span class="hlt">atmosphere</span>-ocean model from 1950 to 2099. The free surface, mass conserving ocean model leads to</p> <div class="credits"> <p class="dwt_author">G. L. Russell; V. Gornitz; J. R. Miller</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">376</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/ruj281w206h76u2g.pdf"> <span id="translatedtitle"><span class="hlt">Atmospheric</span> cycling and air-water exchange of mercury over mid-continental lacustrine <span class="hlt">regions</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Atmospheric</span> mobilization and exchange at the air-water interface are significant features of biogeochemical cycling of Hg\\u000a at the Earth's surface. Our marine studies of Hg have been extended to terrestrial aquatic systems, where we are investigating\\u000a the tropospheric cycling, deposition and air-water exchange of Hg in the mid-continental lacustrine environs of northcentral\\u000a Wisconsin. This program is part of a multidisciplinary</p> <div class="credits"> <p class="dwt_author">William F. Fitzgerald; R. P. Mason; G. M. Vandal</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">377</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54008210"> <span id="translatedtitle">Interannual variability in the <span class="hlt">atmospheric</span> CO2 rectification over a boreal forest <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ecosystem CO2 exchange with the <span class="hlt">atmosphere</span> and the planetary boundary layer (PBL) dynamics are correlated diurnally and seasonally. The strength of this kind of covariation is quantified as the rectifier effect, and it affects the vertical gradient of CO2 and thus the global CO2 distribution pattern. An 11-year (1990-1996, 1999-2002), continuous CO2 record from Fraserdale, Ontario (49°52'29.9''N, 81°34'12.3''W), along with</p> <div class="credits"> <p class="dwt_author">Baozhang Chen; Jing M. Chen; Douglas E. J. Worthy</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">378</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/jd/jd0516/2004JD005546/2004JD005546.pdf"> <span id="translatedtitle">Interannual variability in the <span class="hlt">atmospheric</span> CO2 rectification over a boreal forest <span class="hlt">region</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ecosystem CO2 exchange with the <span class="hlt">atmosphere</span> and the planetary boundary layer (PBL) dynamics are correlated diurnally and seasonally. The strength of this kind of covariation is quantified as the rectifier effect, and it affects the vertical gradient of CO2 and thus the global CO2 distribution pattern. An 11-year (1990–1996, 1999–2002), continuous CO2 record from Fraserdale, Ontario (49°52?29.9?N, 81°34?12.3?W), along with</p> <div class="credits"> <p class="dwt_author">Baozhang Chen; Jing M. Chen; Douglas E. J. Worthy</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">379</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/25460943"> <span id="translatedtitle">Downwash of <span class="hlt">atmospherically</span> deposited trace metals in peat and the <span class="hlt">influence</span> of rainfall intensity: An experimental test.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Accumulation records of pollutant metals in peat have been frequently used to reconstruct past <span class="hlt">atmospheric</span> deposition rates. While there is good support for peat as a record of relative changes in metal deposition over time, questions remain whether peat archives represent a qu