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1

Regional atmospheric influence on the Chandler wobble  

NASA Astrophysics Data System (ADS)

From the maps of regional contribution to atmospheric angular momentum (AAM) over the period 1948-2011 (NCEP/NCAR reanalysis data) time domain excitation in Chandler frequency band was extracted by Panteleev's filtering method. This permits us to investigate the evolution of the regional atmospheric influence on Chandler wobble. It appears that the temperate latitudes bring the strongest inputs. For pressure term they are limited to continents, and highlight the role of Europe. For the wind term they mostly result from ocean area, encompassing in particular North Atlantic. A quasi-20 year cycle is found in the regional patterns of the atmospheric excitation. The integrated AAM is finally compared with the geodetic excitation reconstructed from the observed polar motion.

Zotov, L. V.; Bizouard, C.

2015-03-01

2

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

3

Influence of atmospheric nutrients on primary productivity in a coastal upwelling region  

E-print Network

of nitrogen (N) annually, but if the estimate is expanded to encompass the effects of iron (Fe), aerosols may carbon dioxide concentrations and climate. Accordingly, under- standing the role of atmospheric sources, including fluvial and groundwater inputs, such that the rel- ative contribution of atmospheric

Paytan, Adina

4

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

5

The Mid Summer Drought in Middle and Central Americas as simulated by a regional atmosphere-ocean model. Regional extent and the ocean remote and local influences  

NASA Astrophysics Data System (ADS)

A 30 year model climatology (1979-2010) is analyzed to study the tendencies and variability of the Mid Summer Drought comparing against the CRU observed climatology over the same period. The model used is a state-of-the-art regional atmosphere-ocean coupled model (REMO) developed at the Max Planck Institute for Meteorology. A simulation with 0.5 degree horizontal resolution is used to perform the analysis of precipitation over the region. Inspection of model annual and seasonal precipitation reveals that these compare well with CRU observed climatology both in amplitude and pattern. The exception is Southern Mexico and portions of Central America which the model underestimates during the rainy seasons. However, the spatial patterns of the Mid Summer Drought (MSD) are well represented over Mexico and Central America. It is found that both the onset and end of the MSD over Southern Mexico are profoundly influenced by the state of the Eastern Pacific Ocean particularly in the Isthmus of Tehuantepec and Central America. On this model climatology the remote influence of Atlantic and Pacific oceans plays a crucial role in the second pluvial peak at the end of the MSD around September.

Martinez-Lopez, B.; Cabos, W.; Quintanar Isaias, A.

2013-05-01

6

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

7

Study on the atmospheric boundary layer and its influence on regional air quality over the Pearl River delta  

NASA Astrophysics Data System (ADS)

To study the structure of atmospheric boundary layer (ABL) and its influence on regional air quality over the Pearl River delta (PRD), two ABL intensive observations were conducted at Panyu (urban station) and Xinken (non-urban station, near estuary) of PRD during October 2004 and July 2006, respectively. Based on the ABL intensive observation data analysis, the typical weather condition type associated with poor air quality over PRD could be summarized into two kinds: the warmed period before cold front (WPBCF) and the subsidence period controlled by tropical cyclone (SPCTC). Two typical polluted cases (affected by WPBCF and SPCTC, respectively) and one clean (not-polluted) case were chosen for detail analysis. It was found that the continuously low or calm ground wind would lead to pollutant accumulation. The local circulation, such as sea-land breezes and heat-island circulation, played an important role in these polluted cases. The recirculation was significant in polluted cases; steady transport occurred in the clean case. Ventilation index (VI) was quite different between polluted cases and the clean case: in WPBCF cases, the peak VI was from 184 to 3555 m2 s-1; on SPCTC days, the peak VI was from 1066 to 4363 m2 s-1; on the clean day, the peak VI was 10 885 m2 s-1 and much larger than all polluted cases. The 24-h average VI on polluted days was from 169 to 2858 m2 s-1 and also much smaller than that of the clean day. VI is a good reference index for pollution judgment. The peak mixing heights were smaller than 700 m in WPBCF cases, and were smaller than 800 m in SPCTC cases. During WPBCF polluted case, only surface inversion layer appeared. In the period of land breeze, surface inversion layer height was about 50 m, but in the period of sea breeze, surface inversion layer height would increase, and reach the maximum height, which was about 600 m. During SPCTC polluted case, there were several inversion layers that appeared at different heights. The lowest was about 50 m, the highest about 800 m, with the vertical temperature profile quite complex.

Wu, M.; Wu, D.; Fan, Q.; Wang, B. M.; Li, H. W.; Fan, S. J.

2013-03-01

8

The use of an atmospheric dispersion model to determine influence regions in the Prince George, B.C. airshed from the burning of open wood waste piles.  

PubMed

A means of determining air emission source regions adversely influencing the city of Prince George, British Columbia, Canada from potential burning of isolated piles of mountain pine beetle-killed lodge pole pine is presented. The analysis uses the CALPUFF atmospheric dispersion model to identify safe burning regions based on atmospheric stability and wind direction. Model results show that the location and extent of influence regions is sensitive to wind speed, wind direction, atmospheric stability and a threshold used to quantify excessive concentrations. A concentration threshold based on the Canada Wide PM(2.5) Standard is used to delineate the influence regions while Environment Canada's (EC) daily ventilation index (VI) is used to quantify local atmospheric stability. Results from the analysis, to be used by air quality meteorologists in assessing daily requests for burning permits, are presented as a series of maps delineating acceptable burning locations for sources placed at various distances from the city center and under different ventilation conditions. The results show that no burning should be allowed within 10 km of the city center; under poor ventilation conditions, no burning should be allowed within 20 km of the city center; under good ventilation conditions, burning can be allowed within 10-15 km of the city center; under good to fair ventilation conditions, burning can be allowed beyond 15 km of the city center; and if the wind direction can be reliably forecast, burning can be allowed between 5 and 10 km downwind of the city center under good ventilation conditions. PMID:19303193

Ainslie, B; Jackson, P L

2009-06-01

9

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.

10

Atmospheric composition - Influence of biology  

NASA Technical Reports Server (NTRS)

The variability of atmospheric constituents influenced by biological organisms over various time scales is examined, together with the human contribution to atmospheric sulfur. The biogeochemistry of nitrogen is discussed, with an emphasis on N2O, NO, and microbially mediated reactions in soil and water. Carbon species are bound up mainly in sediments and the deep ocean, but human activities involving combustion may cause a doubling of the atmospheric levels of CO2 in the near future, which could produce a general low-level atmospheric warming. Longer term measurements are required to assess the effects of CH4 augmentation in the atmosphere through fuel combustion. Coal burning effectively doubles the amount of SO2 produced by natural sources, and reduces the pH of rainwater, thus posing hazards to fish, plankton, and mollusc life.

Mcelroy, M. B.

1983-01-01

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

Experimental evaluation of atmospheric aerosol turbidity in different Atlantic regions  

SciTech Connect

The statistical estimation of the experimental values of atmospheric turbidity are considered over the different Atlantic regions: from clean atmospheric conditions to very turbid conditions influenced by air masses from Africa containing continental Sahara aerosol. The factors influencing the variability of atmospheric turbidity are also analyzed. The contribution of aerosol to atmospheric attenuation of the direct solar radiation is estimated. It is shown that aerosol is the main factor determining the values of the optical thickness and its variability. The single scattering albedo is evaluated. The influence of the Sahara dust on the total solar radiation over the ocean surface is estimated. Based on the found relationship between aerosol optical thickness, total atmosphere, and aerosol turbidity in the surface layer, the height of the homogeneous atmosphere has been estimated. In addition, the aerosol generation by ocean surface in storm conditions has been considered.

Plakhina, I.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics; Pyrogov, S.M. [Russian Academy of Sciences, Moscow (Russian Federation). Lab. of Atmosphere Ocean Interaction

1994-12-31

13

Metal contamination and health risk from consumption of organically grown vegetables influenced by atmospheric deposition in a seasonally dry tropical region of India.  

PubMed

Pot-culture experiments showed that organically grown Vicia faba, influenced by atmospheric deposition, accumulated (?g g(-1)) 0.088-3.246 Cadmium, 0.19-42.48 Chromium, 0.0124-30.43 Copper, 0.075-4.28 Lead and 0.63-67.68 Zinc. Similar trends appeared for Abelmoschus esculentus. At high deposition sites, Cadmium, Lead and Zinc exceeded the safe limits of Prevention of Food Adulteration standards. Health risk index for Cadmium, Copper and Lead exceeded the safe limits of United States Environmental Protection Agency. The study suggests that atmospheric deposition could substantially elevate metal levels in organically grown vegetables in 2011. PMID:22653308

Singh, Ashima; Pandey, Jitendra

2012-08-01

14

The Regional Atmospheric Modeling System  

E-print Network

and interaction of clouds and precipitating liquid and ice hydrometeors, sensible and latent heat exchange between software utilities. The atmospheric model is constructed around the full set of primitive dynamical

Gohm, Alexander

15

Atmospheric Influence of Earth's Earliest Sulfur Cycle  

Microsoft Academic Search

Mass-independent isotopic signatures for delta33S, delta34S, and delta36S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric

James Farquhar; Huiming Bao; Mark Thiemens

2000-01-01

16

Influence of temperature, moisture, and organic carbon on the flux of H2 and CO between soil and atmosphere: Field studies in subtropical regions  

NASA Astrophysics Data System (ADS)

Production and deposition rates of atmospheric hydrogen and carbon monoxide were studied during field measurements in subtropical regions, i.e., Transvaal (South Africa), Andalusia (Spain), and the Karoo (South Africa). Measurements were carried out by applying static and equilibrium box techniques. The equilibrium technique has been introduced as a novel method to measure production and destruction rates simultaneously even when soil conditions (e.g., temperature) change during the course of the measurements. Deposition velocities of H2 and CO were virtually independent of the soil temperature measured in 3- to 10-mm depths and agreed with those measured in the temperate regions. The deposition velocities were inhibited or stimulated by irrigation water depending on the conditions of the individual field sites. H2 production by soil was not observed. By contrast, CO was produced by soil in a dark chemical reaction. Production rates increased exponentially with soil temperatures, giving activation energies of 57-110 kJ mol-1 and increased linearly with soil organic carbon content. CO production rates followed a diel rhythm parallel to soil surface temperatures. Production generally exceeded CO deposition during the hot hours of the day, so that arid subtropical soils act as a net source of atmospheric CO during this time. On a global basis, CO production by soil may reach source strengths of 30 Tg yr-1, which is considerably less than the global deposition of CO estimated to be 190-580 Tg yr-1. Global H2 deposition rates were estimated to 70-110 Tg yr-1.

Conrad, Ralf; Seiler, Wolfgang

1985-06-01

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

Lunar influence on equatorial atmospheric angular momentum  

NASA Astrophysics Data System (ADS)

This study investigates the relationship between the equatorial atmospheric angular momentum oscillation in the nonrotating frame and the quasi-diurnal lunar tidal potential. Between 2 and 30 days, the corresponding equatorial component, called Celestial Atmospheric Angular Momentum (CEAM), is mostly constituted of prograde circular motions, especially of a harmonic at 13.66 days, a sidelobe at 13.63 days, and of a weekly broadband variation. A simple equilibrium tide model explains the 13.66 day pressure term as a result of the O1 lunar tide. The powerful episodic fluctuations between 5 and 8 days possibly reflect an atmospheric normal mode excited by the tidal waves Q1 (6.86 days) and ?1 (7.095 days). The lunar tidal influence on the spectral band from 2 to 30 days is confirmed by two specific features, not occurring for seasonal band dominated by the solar thermal effect. First, Northern and Southern Hemispheres contribute equally and synchronously to the CEAM wind term. Second, the pressure and wind terms are proportional, which follows from angular momentum budget considerations where the topographic and friction torques on the solid Earth are much smaller than the one resulting from the equatorial bulge. Such a configuration is expected for the case of tidally induced circulation, where the surface pressure variation is tesseral and cannot contribute to the topographic torque, and tidal winds blow only at high altitudes. The likely effects of the lunar-driven atmospheric circulation on Earth's nutation are estimated and discussed in light of the present-day capabilities of space geodetic techniques.

Bizouard, Christian; Zotov, Leonid; Sidorenkov, Nikolay

2014-11-01

19

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

20

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

21

A new mechanism for regional atmospheric chemistry modeling  

Microsoft Academic Search

A new gas-phase chemical mechanism for the modeling of regional atmospheric chemistry, the ``Regional Atmospheric Chemistry Mechanism'' (RACM) is presented. The mechanism is intended to be valid for remote to polluted conditions and from the Earth's surface through the upper troposphere. The RACM mechanism is based upon the earlier Regional Acid Deposition Model, version 2 (RADM2) mechanism [Stockwell et al.,

William R. Stockwell; Frank Kirchner; Michael Kuhn; Stephan Seefeld

1997-01-01

22

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

23

Topographic Influence and Atmospheric Dynamics in the Indian Wells Valley  

NASA Astrophysics Data System (ADS)

Indian Wells Valley (IWV) is home to the China Lake Naval Air Weapons Station (NAWS) whose operations necessitate regional forecasting and weather analysis relevant to aviation and plume release scenarios. In order to better understand the terrain influenced mesoscale circulations in the varied complex terrain of Indian Wells Valley surrounding Ridgecrest, four seasonal WRF simulations were analyzed using linear shallow water theory and nonlinear theory for flows over two-dimensional mountains. The goal is to better understand the relationships between atmospheric dynamical processes and the wind/thermal structure of the mesoscale at Indian Wells Valley. This will involve exploring relationships linking theoretical meteorology in complex terrain and advanced high resolution atmospheric modeling in this region. The WRF simulation results show several distinct circulations which rely on the interaction between complex terrain and the background weather conditions: 1) In calm synoptic conditions, diurnal processes guide the evolution of boundary layer stability and slope flows. 2) In periods of greatest seasonal surface heating (i.e. summer), the pressure gradient across the Sierra Nevada drives near surface westerlies across IWV. 3) In conditions with strong synoptic scale increase in stability and meridional winds across the Sierra Nevada, a downslope windstorm can develop in IWV. The downslope winds and compensatory gravity wave activity over IWV will conclude once there is a significant change in conditions aloft, or an increase in convective instability at the surface of IWV which prevents air aloft from sinking towards the surface. These results provide a better understanding of the mesoscale meteorology in this region and improve forecast and analysis for plume transport and aviation needs while also laying the groundwork for future projects managing environmental concerns in this region.

Uher, Erich J.

24

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  

Microsoft Academic Search

Mineral particles could have influenced on the climate of Oviedo, a non-industrial city situated in the centre of an industrial\\u000a zone of the North of Spain, increasing the temperature and the precipitations, in spite of the fact that “greenhouse gases”\\u000a concentrations have diminished in this city in recent years. The directive (1999\\/30\\/EC) of the European Commission began to\\u000a be applied

Irene Rodríguez; Salvador Galí; Celia Marcos

2009-01-01

25

Atmospheric Turbulence and its Influence on Adaptive Optics  

E-print Network

Atmospheric Turbulence and its Influence on Adaptive Optics Mike Campbell 23rd Summary 10 ii #12;1 Introduction Adaptive Optics (AO) is still a relatively young branch of astronomical of adaptive optics is to remove the distortions created by the atmosphere. To apply a change which flattens

Tittley, Eric

26

Influence of bonding atmosphere on low-temperature wafer bonding  

Microsoft Academic Search

The influence of bonding atmosphere was investigated for the wafer bonding at 25~200°C using a surface activated bonding method. The results of the analysis of activated Si surfaces under different vacuum background and the residual gases in vacuum before and after Ar fast atom beam irradiation is reported. Based on the analysis, bonding of Si wafers in nitrogen atmosphere is

Ying-Hui Wang; Tadatomo Suga

2010-01-01

27

ORIGINAL PAPER The influence of plants on atmospheric methane  

E-print Network

on atmospheric methane (CH4) in an agriculture-dominated landscape in the Upper Mid- west of the United StatesORIGINAL PAPER The influence of plants on atmospheric methane in an agriculture-dominated landscape plants were measured with a laser-based plant chamber system. At the landscape scale, the land surface

Minnesota, University of

28

INFLUENCE OF AGRICULTURAL PRACTICES ON MICROMETEOROLOGICAL SPATIAL VARIATIONS AT THE LOCAL AND REGIONAL SCALES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil - vegetation - atmosphere transfers significantly influence interactions and feedbacks between vegetation and boundary layer, in relation with plant phenology and water status. The current study focused on linking micrometeorological conditions to cultural practices at the local and regional sc...

29

Influence of Agricultural Practices on Micrometerological Spatial Variations at Local and Regional Scales  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil-vegetation-atmosphere transfers significantly influence interactions and feedbacks between vegetation and boundary layer in relation with plant phenology and water status. The current study focused on linking micrometeorological conditions to cultural practices at the local and regional scales ...

30

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

31

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

32

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

33

Regional Forest-Atmosphere Carbon Exchange via Atmospheric Inversions and Flux-Tower Upscaling  

Microsoft Academic Search

The overarching goal of a long-term regional study of ecosystem-atmosphere carbon cycling in a mixed forest ecosystem in the upper Midwest is to observe ecosystem-atmosphere exchange of carbon dioxide at scales of relevance to the global carbon balance, while simultaneously understanding the mechanisms governing this exchange. The Chequamegon Ecosystem-Atmosphere Study (ChEAS) brings together chamber flux, sap flux and biometric measurements

K. Davis; A. Andrews; J. Berry; P. Bolstad; J. Chen; B. Cook; A. S. Denning; A. Desai; F. Heinsch; B. Helliker; N. Miles; A. Noormets; D. Ricciuto; S. Richardson; M. Uliasz; W. Wang

2005-01-01

34

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

35

Influences of Atmospheric Stability State on Wind Turbine Aerodynamic Loadings  

NASA Astrophysics Data System (ADS)

Wind turbine power and loadings are influenced by the structure of atmospheric turbulence and thus on the stability state of the atmosphere. Statistical differences in loadings with atmospheric stability could impact controls, blade design, etc. Large-eddy simulation (LES) of the neutral and moderately convective atmospheric boundary layer (NBL, MCBL) are used as inflow to the NREL FAST advanced blade-element momentum theory code to predict wind turbine rotor power, sectional lift and drag, blade bending moments and shaft torque. Using horizontal homogeneity, we combine time and ensemble averages to obtain converged statistics equivalent to ``infinite'' time averages over a single turbine. The MCBL required longer effective time periods to obtain converged statistics than the NBL. Variances and correlation coefficients among wind velocities, turbine power and blade loadings were higher in the MCBL than the NBL. We conclude that the stability state of the ABL strongly influences wind turbine performance. Supported by NSF and DOE.

Vijayakumar, Ganesh; Lavely, Adam; Brasseur, James; Paterson, Eric; Kinzel, Michael

2011-11-01

36

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

37

Identifying human influences on atmospheric temperature.  

PubMed

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

38

Regional atmospheric composition modeling with CHIMERE  

NASA Astrophysics Data System (ADS)

Tropospheric trace gas and aerosol pollutants have adverse effects on health, environment and climate. In order to quantify and mitigate such effects, a wide range of processes leading to the formation and transport of pollutants must be considered, understood and represented in numerical models. Regional scale pollution episodes result from the combination of several factors: high emissions (from anthropogenic or natural sources), stagnant meteorological conditions, velocity and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative importance to the pollutants budgets can be quantified within a chemistry-transport models (CTM). The offline CTM CHIMERE model uses meteorological model fields and emissions fluxes and calculates deterministically their behavior in the troposphere. The calculated three-dimensional fields of chemical concentrations can be compared to measurements to analyze past periods or used to make air quality forecasts and CHIMERE has enabled a fine understanding of pollutants transport during numerous measurements campaigns. It is a part of the PREVAIR french national forecast platform, delivering pollutant concentrations up to three days in advance. The model also allows scenario studies and long term simulations for pollution trends. The modelling of photochemical air pollution has reached a good level of maturity, and the latest projects involving CHIMERE now aim at increasing our understanding of pollution impact on health at the urban scale or at the other end of the spectrum for long term air quality and climate change interlinkage studies, quantifying the emissions and transport of pollen, but also, at a larger scale, analyzing the transport of pollutants plumes emitted by volcanic eruptions and forest fires.

Menut, L.; Bessagnet, B.; Khvorostyanov, D.; Beekmann, M.; Colette, A.; Coll, I.; Curci, G.; Foret, G.; Hodzic, A.; Mailler, S.; Meleux, F.; Monge, J.-L.; Pison, I.; Turquety, S.; Valari, M.; Vautard, R.; Vivanco, M. G.

2013-01-01

39

Mass conservation and atmospheric dynamics in the Regional Atmospheric Modeling System (RAMS)  

Microsoft Academic Search

This paper examines the spatio-temporal patterns of atmospheric carbon dioxide transport predicted by the Regional Atmospheric Modeling System (RAMS). Forty-eight hour simulations over northern New England incorporating a simple representation of the diurnal summertime surface carbon dioxide forcing arising from biological activity indicate that, in its native formulation, RAMS exhibits a significant degree of mass non-conservation. Domain-wide rates of non-physical

David Medvigy; Paul R. Moorcroft; Roni Avissar; Robert L. Walko

2005-01-01

40

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...

41

Atmospheric measurements of water vapor in the 442-nm region  

Microsoft Academic Search

In recent years much interest has been generated in the atmospheric community concerning low resolution water vapor cross sections in the blue spectral region. Proper removal of water absorption from long path tropospheric and zenith sky stratospheric measurements has posed a significant problem for recovery of absorption spectra of low concentration molecular species which overlap the water vapor spectrum. The

J. W. Harder; J. W. Brault

1997-01-01

42

Influence of dust loading on atmospheric ionizing radiation on Mars  

NASA Astrophysics Data System (ADS)

Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

2014-01-01

43

Influence of Dust Loading on Atmospheric Ionizing Radiation on Mars  

NASA Technical Reports Server (NTRS)

Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

2014-01-01

44

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

45

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

46

Multi-scale atmospheric composition modelling for the Balkan region  

NASA Astrophysics Data System (ADS)

Overview The present work describes the progress in developing of an integrated, multi-scale Balkan region oriented modeling system. The main activities and achievements at this stage of the work are: Creating, enriching and updating the necessary physiographic, emission and meteorological data bases; Installation of the models for GRID application, model tuning and validation; Extensive numerical simulations on regional (Balkan Peninsula) and local (Bulgaria) scales. Objevtives: The present work describes the progress of an application developed by the Environmental VO of the 7FP project SEE-GRID eInfrastructure for regional eScience. The application aims at developing of an integrated, multi-scale Balkan region oriented modelling system, which would be able to: -Study the atmospheric pollution transport and transformation processes (accounting also for heterogeneous chemistry and the importance of aerosols for air quality and climate) from urban to local to regional (Balkan) scales; -Track and characterize the main pathways and processes that lead to atmospheric composition formation in different scales; -Account for the biosphere-atmosphere exchange as a source and receptor of atmospheric chemical species; -Provide high quality scientifically robust assessments of the air quality and its origin, thus facilitating formulation of pollution mitigation strategies at national and Balkan level. The application is based on US EPA Models-3 system. Description of work: The main activities and achievements at this still preparatory stage of the work are: 1.) Creating, enriching and updating the necessary physiographic, emission and meteorological data bases 2.) Installation of the models for GRID application, model tuning and validation, numerical experiments and interpretation of the results: The US EPA Models 3 system is installed; software for emission speciation and for introducing emission temporal profiles is created, a procedure for calculating biogenic VOC emissions by using the SMOKE abilities is developed; Model validation tests for episodes of very high PM10 concentrations over Germany in February and March of 2003. 3.) Extensive numerical simulations on regional (Balkan Peninsula) and local (Bulgaria) scales are performed aiming at: - better understanding and quantifying of the role of different processes and scales - evaluation of different sources (countries and/or SNAP categories) contribution to air pollution formation on local to regional scales Conclusions and Future Work: The present work is an attempt to development of an integrated view of the atmospheric composition formation at different spatial and temporal scales. It is also envisaged some studies to be carried out aiming at assessment of climate change impact on air pollution levels in Bulgaria. A natural sequel of the present work will be the creation of Bulgarian national chemical weather forecasting and information system.

Ganev, Kostadin; Syrakov, Dimiter; Todorova, Angelina; Prodanova, Maria; Atanasov, Emanouil; Gurov, Todor; Karaivanova, Aneta; Miloshev, Nikolai; Gadzhev, Georgi; Jordanov, Georgi

2010-05-01

47

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

48

Role of solar influences on geomagnetosphere and upper atmosphere  

NASA Astrophysics Data System (ADS)

The Earth's magnetosphere and upper atmosphere can be greatly perturbed by variations in the solar luminosity caused by disturbances on the solar surface. The state of near-Earth space environment is governed by the Sun and is very dynamic on all spatial and temporal scale. The geomagnetic field which protects the Earth from solar wind and cosmic rays is also essential to the evolution of life; its variations can have either direct or indirect effect on human physiology and health state even if the magnitude of the disturbance is small. Geomagnetic disturbances are seen at the surface of the Earth as perturbations in the components of the geomagnetic field, caused by electric currents flowing in the magnetosphere and upper atmosphere. Ionospheric and thermospheric storms also result from the redistribution of particles and fields. Global thermospheric storm winds and composition changes are driven by energy injection at high latitudes. These storm effects may penetrate downwards to the lower thermosphere and may even perturb the mesosphere. Many of the ionospheric changes at mid-latitude can be understood as a response to thermospheric perturbations. The transient bursts of solar energetic particles, often associated with large solar transients, have been observed to have effects on the Earth's middle and lower atmosphere, including the large-scale destruction of polar stratospheric and tropospheric ozone. In the present, we have discussed effect of solar influences on earth's magnetosphere and upper atmosphere that are useful to space weather and global warming, on the basis of various latest studies.

Kumar Tripathi, Arvind

49

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

50

A subtropical North Atlantic regional atmospheric moisture budget  

NASA Astrophysics Data System (ADS)

The 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

51

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

52

Atmospheric Pollution and Emission Sources in South Asian Urban Region  

NASA Astrophysics Data System (ADS)

Rapid urbanization, and lack of efficient monitoring and control of pollution, along with phenomena like Asian Brown Haze or prolonged episodes of winter fog, makes the South Asian atmospheric chemistry a very complex one. The anthropogenic aerosols released from this region are projected to become the dominant component of anthropogenic aerosols worldwide in the next 25 years (Nakicenovic and Swart, 2000). The region is one of the most densely populated in the world, with present population densities of 100-500 persons km-2. There are six big cities, namely, Delhi, Dhaka, Karachi, Kolkata, Lahore, and Mumbai, each housing a population around or above 10 million. There is now a real concern about the sustainability of the region's ability to support the population due to air pollution, loss of biodiversity and soil degradation. Therefore, we conducted several extensive campaigns over last 10 years in Lahore, Karachi, and Islamabad in Pakistan to (1) chemically characterize the aerosols (PM2.5 mass, concentrations of trace elements, ions, black and organic carbon), and gaseous pollutants (concentrations of NH3, SO2, HONO, HNO3, HCl and (COOH)2, and (2) identify the major emission sources in this region. Exceedingly high concentrations of all species, relative to major urban areas of US and Europe, were observed. Concentrations of PM2.5, BC, Pb, SO42-, NH4+, HONO, NH3 respectively, up to 476, 110, 12, 66, 60, 19.6 and 50 ?gm-3 were observed in these cities, which were far in excess of WHO and US EPA air quality standard (Biswas et al., 2008). We use air parcel back trajectories, intercomponent relationships and meteorological observations to explain chemistry and emission sources of aerosol constituents. Carbonaceous aerosols contributed up to 69% of the PM2.5 mass (Husain et al., 2007). Source apportionment was conducted using positive matrix factorization. The analysis has classified six emission sources of aerosol components, namely, industrial activities, wood burning, secondary aerosols, metal processing, vehicular emissions, and crustal and road dust. Findings of our study will play a vital role in adopting a strategy to regulate emissions, and to mitigate the long-term climate change in the region. References: Nakicenovic, N. and Swart, R., 2000. In: N. Nakicenovic and R. Swart, Eds, Emissions Scenarios 2000. Special Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge. Biswas, K.F., Ghauri, B.M., Husain, L., 2008. Gaseous and aerosol pollutants during fog and clear episodes in South Asian urban atmosphere. Atmospheric Environment, 42, 7775-7785. Husain, L., Dutkiewicz, V.A., Khan, A.J., Ghauri, B.M., 2007. Characterization of carbonaceous aerosols in urban air. Atmospheric Environment, 41, 6872-6883.

Biswas, K. F.; Husain, Liaquat

2009-04-01

53

A new mechanism for regional atmospheric chemistry modeling  

NASA Astrophysics Data System (ADS)

A new gas-phase chemical mechanism for the modeling of regional atmospheric chemistry, the "Regional Atmospheric Chemistry Mechanism" (RACM) is presented. The mechanism is intended to be valid for remote to polluted conditions and from the Earth's surface through the upper troposphere. The RACM mechanism is based upon the earlier Regional Acid Deposition Model, version 2 (RADM2) mechanism [Stockwell et al., 1990] and the more detailed Euro-RADM mechanism [Stockwell and Kley, 1994]. The RACM mechanism includes rate constants and product yields from the most recent laboratory measurements, and it has been tested against environmental chamber data. A new condensed reaction mechanism is included for biogenic compounds: isoprene, ?-pinene, and d-limonene. The branching ratios for alkane decay were reevaluated, and in the revised mechanism the aldehyde to ketone ratios were significantly reduced. The relatively large amounts of nitrates resulting from the reactions of unbranched alkenes with NO3 are now included, and the production of HO from the ozonolysis of alkenes has a much greater yield. The aromatic chemistry has been revised through the use of new laboratory data. The yield of cresol production from aromatics was reduced, while the reactions of HO, NO3, and O3 with unsaturated dicarbonyl species and unsaturated peroxynitrate are now included in the RACM mechanism. The peroxyacetyl nitrate chemistry and the organic peroxy radical-peroxy radical reactions were revised, and organic peroxy radical +NO3 reactions were added.

Stockwell, William R.; Kirchner, Frank; Kuhn, Michael; Seefeld, Stephan

1997-11-01

54

Simulation of fog influence on laser beam distribution in atmosphere  

NASA Astrophysics Data System (ADS)

Optical fibreless data networks P2P offer fast data transmissions with big transmittance from 1- 10 Gbps on a distance of 1- 6 km. Perfections of such networks are especially flexibility, rapid creation of communications. Sensitivity to atmospheric influences, necessity of light on sight belongs to disadvantages. Transmission through atmosphere be characterized by non-stationarity, inhomogeneity, the influences have random character. It means immediately that it is possible only with difficulty to project conclusions concerning to the measurement on one line upon fiberless line in another position. Contribution tackles a question of forming of the artificial hazy atmospheres, finding the statistical parameters of artificially created foggy atmospheres that could be reproduced to real environment. This work describes created laboratory apparatus powered with fog generator, heat source and ventilating fans, which allow in a controlled way to change the optical transmission inside the bounded space. Laser diode radiation at wavelength of 850 nm is transmitted into created space like this which is scanned with optical power meter after passing of artificially created turbulent vaporous environment. Changes in intensity of the passed lights are captured; the mean value and maximum deviation from the mean value are computed. In this way it is possible to change the reached specific attenuation in dB/km. Owing to turbulences it happens to deviations from the mean value, these abnormalities are characterized by the distribution function that describes the size of turbulences in time. By the help of ergodic theorem then it is possible to deduce that the distribution function of the foggy turbulences gained at continuous time evaluation has same history like the distribution function gained behind the same conditions in the setup in other times. It holds as well that these distribution functions are the same for variety of points in experimental space, provided there are well - kept the same conditions of turbulence creations. Contribution shows the experimental values, shapes of distribution functions, their influence on attenuation of fiberless communication lines and on achieved the transmission BER. At the present time the verification of conclusions is performed from the experimental model on outdoor connecting link working upon the distance of 1,3 km at the transmission rate of 1,25 Gbps.

Vasinek, Vladimir; Latal, Jan; Koudelka, Petr; Vitasek, Jan; Witas, Karel; Hejduk, Stanislav

2012-10-01

55

Dynamo region and the equatorial electrojet in the Jovian atmosphere  

NASA Astrophysics Data System (ADS)

The existence of the dynamo region is identified in the atmosphere of Jupiter. It is found that the dynamo region extends from an altitude of 130 km (0.153 mbar) to 330 km (0.027 microbar) reckoned from zero altitude corresponding to 43.8 mbar pressure level. Physical features of the equatorial electrojet in the ionosphere of Jupiter are modelled in detail. The Jovian equatorial electrojet has a maximum eastward current density of about 1.5 A/sq km at an altitude of 270 km (0.33 microbar) with a latitudinal half width of about + or - 11 degrees. The thickness of the equatorial half width is 100 km in altitude range. The type I instability in the electrojet can exist only if the electron streaming velocity exceeds the value of about 250 m/s.

Raghavarao, R.; Dagar, R.

1983-06-01

56

Regional modeling of surface-atmosphere interactions and their impact on Great Lakes hydroclimate  

NASA Astrophysics Data System (ADS)

Land and water surfaces play a critical role in hydroclimate by supplying moisture to the atmosphere, yet the ability of climate models to capture their feedbacks with the atmosphere relative to large-scale transport is uncertain. To assess these land-lake-atmosphere feedbacks, we compare the controls on atmospheric moisture simulated by a regional climate model (RegCM) with observations and reanalysis products for the Great Lakes region. Three 23 year simulations, driven by one reanalysis product and two general circulation models, are performed. RegCM simulates wetter winters and drier summers than observed by up to 31 and 21%, respectively. Moisture advection exhibits similar biases, suggesting the contribution of external sources. Land surface fluxes account for nearly one third of summer precipitation according to two reanalysis products. RegCM underestimates reanalysis evapotranspiration by nearly 50%; however, the reanalyses overestimate measurements at three FLUXNET sites by up to a factor of 2, which may explain the model-reanalysis differences. Neither RegCM nor the reanalyses capture the spatial variability in land evapotranspiration observed across the three FLUXNET sites, indicating a source of model uncertainty. In addition, RegCM underestimates the observed evapotranspiration response to its atmospheric drivers such as vapor pressure deficit and temperature. Over the lakes, one model member overestimates convective precipitation caused by enhanced evaporation under warm lake surface temperatures, highlighting the need for accurate representation of lake temperature in the surface boundary condition. We conclude that climate models, including those driving reanalyses, underestimate the observed surface-atmosphere feedbacks and their influence on regional hydroclimate.

Bryan, A. M.; Steiner, A. L.; Posselt, D. J.

2015-02-01

57

Emission inventory evaluation using observations of regional atmospheric background stations of China.  

PubMed

Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region. The INTEX-B2006 (I06), one of the newest emission inventories recently popularly used in China and East Asia, has been assessed using the Community Multiscale Air Quality model and observations from regional atmospheric background stations of China. Comparisons of the model results with the observations for the species SO2, NO2, O3 and CO from the three regional atmospheric background stations of Shangdianzi, Longfengshan and Linan show that the model can basically capture the temporal characteristics of observations such as the monthly, seasonal and diurnal variance trends. Compared to the other three species, the simulated CO values were grossly underestimated by about two-third or one-half of the observed values, related to the uncertainty in CO emissions. Compared to the other two stations, Shangdianzi had poorer simulations, especially for SO2 and CO, which partly resulted from the site location close to local emission sources from the Beijing area; and the regional inventory used was not capable of capturing the influencing factors of strong regional sources on stations. Generally, the fact that summer gave poor simulation, especially for SO2 and O3, might partly relate to poor simulations of meteorological fields such as temperature and wind. PMID:23923427

An, Xingqin; Sun, Zhaobin; Lin, Weili; Jin, Min; Li, Nan

2013-03-01

58

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

59

PUBLISHED ONLINE: 13 JANUARY 2013 | DOI: 10.1038/NGEO1687 Atmospheric iodine levels influenced by sea  

E-print Network

LETTERS PUBLISHED ONLINE: 13 JANUARY 2013 | DOI: 10.1038/NGEO1687 Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine Lucy J. Carpenter1 *, Samantha M. MacDonald2 , Marvin. Plane2 * Naturally occurring bromine- and iodine-containing compounds substantially reduce regional

Jacob, Daniel J.

60

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

61

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

62

ORIGINAL PAPER Local and regional factors influencing assemblages of dragonflies  

E-print Network

ORIGINAL PAPER Local and regional factors influencing assemblages of dragonflies and damselflies the effects of local and regional variables on richness and occurrence rates of Odonata (dragonfly in this study, degree-days and precipi- tation, influenced the richness of dragonflies, but not the less

M'Gonigle, Leithen

63

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

64

Lichens as indicators of the atmosphere state in the oil exploration district of Tomsk Region  

NASA Astrophysics Data System (ADS)

Lichens are widespread in the vegetative cover of West Siberia, particularly in the north. They play an important role in the migration and transformation of chemical pollutants. Lichens lack waxy cuticles and are largely dependent on the atmosphere for their water and nutrient uptake. Lichens are not only studied and used as indicators, but also as accumulators, e.g. for trace and heavy metals. In fact, lichens are known for their ability to accumulate airborne substances to concentrations far greater those in the atmosphere, and the element contents of lichen thalli proved to be directly correlated with environmental levels. Monitoring of the atmosphere pollution using lichens is more efficient than that using snow cover. Because of the long lichen life it is possible to obtain persistent mean characteristics of the ecosystems state. Epiphytic lichens, growing on tree stems are more appropriate to use than that which grow on soil. Epiphytic lichens are more sensitive to changes of the chemical composition of the atmosphere. Pollutants penetrate in the lichen thalli from the atmosphere together with precipitations and dust. Moreover the precipitations are saturated with pollutants when going through crowns of trees and trickling down the steams and branches. Lichen studies are especially important in territories subjected to excessive human activity. Because a great part of Tomsk region (West Siberia, Russia) is the territory of the oil-field exploration, there the atmosphere monitoring is a necessary part of the whole environmental monitoring. The aim of this investigation is the estimation of the influence of oil exploration industry in Tomsk region on the atmosphere by means of the study of epiphytic lichens. Lichen samples were collected in August and September 2010-2011. Sampling net included seven areas distributed inside the oil-exploration districts of Tomsk region. In total 27 samples were collected. In these samples 53 chemical elements were detected by ICP-MS. Comparing the obtained results with the data of other Siberian regions (Yamal and Irkutsk regions) and also, Austria (Zemmering), Finland, Netherlands the authors have revealed excesses for Cr, Co, Zn, As, Rb, ? etc. three and more times.

Bolshunova, Tatiana; Ivan, Podkozlin

2013-04-01

65

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

66

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

67

Influence of wind direction on pollen concentration in the atmosphere  

NASA Astrophysics Data System (ADS)

The daily pollen concentration in the atmosphere of Badajoz (SW Spain) was analysed over a 6-year period (1993-1998) using a volumetric aerobiological trap. The results for the main pollination period are compared with the number of hours of wind each day in the four quadrants: 1 (NE), 2 (SE), 3 (SW) and 4 (NW). The pollen source distribution allowed 16 pollen types to be analysed as a function of their distribution in the four quadrants with respect to the location of the trap. Four of them correspond to species growing in an irrigated farmland environment (Amaranthaceae-Chenopodiaceae, Plantago, Scirpus, and Typha), five to riparian and woodland species (Salix, Fraxinus, Alnus, Populus, and Eucalyptus), four to urban ornamentals (Ulmus, Arecaceae, Cupressaceae, and Casuarina), and three which include the most frequent pollen grains of widely distributed species (Poaceae, Quercus, and Olea). The results show that the distribution of the sources and the wind direction play a very major role in determining the pollen concentration in the atmosphere when these sources are located in certain quadrants, and that the widely distributed pollen sources show no relationship with wind direction. In some years the values of the correlations were not maintained, which leads one to presume that, in order to draw significant conclusions and establish clear patterns of the influence of wind direction, a continuous and more prolonged study will be required.

Silva Palacios, I.; Tormo Molina, R.; Muñoz Rodríguez, A. F.

68

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

69

Influence of atmospheric stability on wind-turbine wakes: A large-eddy simulation study  

NASA Astrophysics Data System (ADS)

In this study, large-eddy simulation is combined with a turbine model to investigate the influence of atmospheric stability on wind-turbine wakes. In the simulations, subgrid-scale turbulent fluxes are parameterized using tuning-free Lagrangian scale-dependent dynamic models. These models optimize the local value of the model coefficients based on the dynamics of the resolved scales. The turbine-induced forces are parameterized with an actuator-disk model with rotation. In this technique, blade-element theory is used to calculate the lift and drag forces acting on the blades. Emphasis is placed on the structure and characteristics of wind-turbine wakes in the cases where the incident flows to the turbine have the same mean velocity at the hub height but different stability conditions. The simulation results show that atmospheric stability has a significant effect on the spatial distribution of the mean velocity deficit and turbulent fluxes in the wake region. In particular, the magnitude of the velocity deficit increases with increasing stability in the atmosphere. In addition, the locations of the maximum turbulence intensity and turbulent stresses are closer to the turbine in convective boundary layer compared with neutral and stable ones. Detailed analysis of the resolved turbulent kinetic energy (TKE) budget inside the wake reveals also that the thermal stratification of the incoming wind considerably affects the magnitude and spatial distribution of the turbulent production, transport term and dissipation rate (transfer of energy to the subgrid scales). It is also shown that the near-wake region can be extended to a farther distance downstream in stable condition compared with neutral and unstable counterparts. In order to isolate the effect of atmospheric stability, additional simulations of neutrally-stratified atmospheric boundary layers are performed with the same turbulence intensity at hub height as convective and stable ones. The results show that the turbulence intensity alone is not sufficient to describe the impact of atmospheric stability on the wind-turbine wakes.

Abkar, Mahdi; Porté-Agel, Fernando

2014-05-01

70

Relationship between atmospheric pressure and mortality in the Madrid Autonomous Region: a time-series study  

NASA Astrophysics Data System (ADS)

This study set out to determine the possible influence of variations in atmospheric pressure on mortality in the Madrid Autonomous Region (MAR), taking into account the possible confounding effect of other atmospheric variables. The study was based on daily mortality data from the MAR Revenue and Excise Authority, meteorological data from Getafe Observatory and air pollution data from the Madrid Municipal Automatic Air Pollution Monitoring Grid. A time-series analysis was performed, using Box-Jenkins modelling and controlling for the respective confounding variables. Furthermore, the different variables studied (pressure, temperature, pollutants, etc.) were used to produce a multivariate model of the different causes of mortality. A significant association was found between anticyclonic trend and mortality with circulatory causes in the medium-long term and anticyclonic trend and mortality with respiratory causes in the long term.

González, S.; Díaz, J.; Pajares, M. S.; Alberdi, J. C.; Otero, A.; López, C.

71

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

72

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

73

The Long-term Middle Atmospheric Influence of Very Large Solar Proton Events  

NASA Technical Reports Server (NTRS)

Long-term variations in ozone have been caused by both natural and humankind related processes. The humankind or anthropogenic influence on ozone originates from the chlorofluorocarbons and halons (chlorine and bromine) and has led to international regulations greatly limiting the release of these substances. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the long-term (> few months) influences of solar proton events from 1963 through 2004 on stratospheric ozone and temperature. There were extremely large solar proton events in 1972, 1989,2000,2001, and 2003. These events caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen-containing compounds, which led to the polar ozone destruction. The nitrogen-containing compounds, called odd nitrogen, lasted much longer than the hydrogen-containing compounds and led to long-lived stratospheric impacts. An extremely active period for these events occurred in the five-year period, 2000- 2004, and caused increases in odd nitrogen which lasted for several months after individual events. Associated stratospheric ozone decreases of >lo% were calculated to last for up to five months past the largest events. However, the computed total column ozone and stratospheric temperature changes connected with the solar events were not found to be statistically significant. Thus, solar proton events do not likely contribute significantly to measured total column ozone fluctuations and stratospheric temperature changes.

Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Randall, Cora E.; Fleming, Eric L.; Frith, Stacey M.

2008-01-01

74

Midlatitude D region variations measured from broadband radio atmospherics  

NASA Astrophysics Data System (ADS)

The high power, broadband very low frequency (VLF, 3--30 kHz) and extremely low frequency (ELF, 3--3000 Hz) electromagnetic waves generated by lightning discharges and propagating in the Earth-ionosphere waveguide can be used to measure the average electron density profile of the lower ionosphere (D region) across the wave propagation path due to several reflections by the upper boundary (lower ionosphere) of the waveguide. This capability makes it possible to frequently and even continuously monitor the D region electron density profile variations over geographically large regions, which are measurements that are essentially impossible by other means. These guided waves, usually called atmospherics (or sferics for short), are recorded by our sensors located near Duke University. The purpose of this work is to develop and implement algorithms to derive the variations of D region electron density profile which is modeled by two parameters (one is height and another is sharpness), by comparing the recorded sferic spectra to a series of model simulated sferic spectra from using a finite difference time domain (FDTD) code. In order to understand the time scales, magnitudes and sources for the midlatitude nighttime D region variations, we analyzed the sferic data of July and August 2005, and extracted both the height and sharpness of the D region electron density profile. The heights show large temporal variations of several kilometers on some nights and the relatively stable behavior on others. Statistical calculations indicate that the hourly average heights during the two months range between 82.0 km and 87.2 km with a mean value of 84.9 km and a standard deviation of 1.1 km. We also observed spatial variations of height as large as 2.0 km over 5 degrees latitudes on some nights, and no spatial variation on others. In addition, the measured height variations exhibited close correlations with local lightning occurrence rate on some nights but no correlation with local lightning or displaced lightning on others. The nighttime profile sharpness during 2.5 hours in two different nights was calculated, and the results were compared to the equivalent sharpness derived from International Reference Ionosphere (IRI) models. Both the absolute values and variation trends in IRI models are different from those in broadband measurements. Based on sferic data similar to those for nighttime, we also measured the day-time D region electron density profile variations in July and August 2005 near Duke University. As expected, the solar radiation is the dominant but not the only determinant source for the daytime D region profile height temporal variations. The observed quiet time heights showed close correlations with solar zenith angle changes but unexpected spatial variations not linked to the solar zenith angle were also observed on some days, with 15% of days exhibiting regional differences larger than 0.5 km. During the solar flare, the induced height change was approximately proportional to the logarithm of the X-ray fluxes. During the rising and decaying phases of the solar flare, the height changes correlated more consistently with the short (wavelength 0.5--4 A), rather than the long (wavelength 1--8 A) X-ray flux changes. The daytime profile sharpness during morning, noontime and afternoon periods in three different days and for the solar zenith angle range 20 to 75 degrees was calculated. These broadband measured results were compared to narrowband VLF measurements, IRI models and Faraday rotation base IRI models (called FIRI). The estimated sharpness from all these sources was more consistent when the solar zenith angle was small than when it was large. By applying the nighttime and daytime measurement techniques, we also derived the D region variations during sunrise and sunset periods. The measurements showed that both the electron density profile height and sharpness decrease during the sunrise period while increase during the sunset period.

Han, Feng

75

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

76

Global and Regional Constraints on Exchanges of CO2 Between the Atmosphere and Terrestrial Biosphere  

NASA Astrophysics Data System (ADS)

The vigorous atmospheric circulation rapidly mixes CO2 that is exchanged with the terrestrial biosphere and oceans. Therefore, at time scales greater than 1 year, the approximate interhemispheric exchange time of the atmosphere, an average of CO2 measurements from a network of surface stations can be used to accurately determine the global net change in atmospheric CO2. By subtracting CO2 produced by fossil fuel combustion, which is well characterized by national statistics, the global the sum of terrestrial biospheric and oceanic net fluxes, here termed the "nonfossil" CO2 flux, can also be accurately determined. The nonfossil CO2 flux averaged -2.1+/-0.3 PgC/yr and -3.2+/-0.4 PgC/yr in the 1980s and 1990s respectively (negative denotes out of the atmosphere), and varied in annual average from about 0 to -4 PgC/yr over these two decades. Two primary methods have been used to further partition the nonfossil CO2 flux between land and oceans: the O2 and 13C/12C methods, which rely, respectively, on measurements of atmospheric O2 (actually O2/N2 for technical reasons) and of the 13C/12C ratio of CO2. Burning of fossil fuel consumes atmospheric O2 and releases CO2 with a 13C/12C ratio lower than that of atmospheric CO2 whereas uptake of CO2 by terrestrial plants releases O2, and increases the atmospheric 13C/12C ratio owing to the preferential assimilation of 12CO2 relative to 13CO2. In contrast, the uptake of CO2 by the oceans has little effect on either the atmospheric O2 or 13C/12C ratio. Therefore, the net CO2 uptake or release from the terrestrial biosphere can be calculated in either method by subtracting the change owing to fossil fuel emissions from the measured change in the atmosphere, utilizing known stoichiometric ratios of O2 and CO2 in the O2 method, and isotopic fractionation factors in the 13C/12C method. Currently, the O2 method gives a net global terrestrial biospheric CO2 flux of -0.2+/-0.7 PgC/yr and -1.4+/-0.7 PgC/yr for the 1980s and the 1990s, respectively. Both the O2 and 13C/12C methods have complications and limitations that will be discussed. To partition the global biospheric flux further to zonal or regional detail or to shorter time steps, atmospheric models are required to simulate the transport of tracer from source regions to individual stations where air is sampled. An ongoing collaborative project to compare atmospheric models has highlighted significant differences in transport characteristics, mainly owing to differences in how the boundary layer is modeled. Accordingly, a recent compilation of model calculations showed a wide range of estimates for the tropical biosphere, from a significant release of CO2 to an uptake over recent decades; however, the calculations showed reasonable agreement on a significant northern biospheric sink. Fluxes of biospheric CO2 can be determined accurately at the global scale as well as at individual sites. An ingenious blend of observations and models will be required to bridge the gap between these two extreme spatial scales, and thereby gain an understanding sufficient to predict the influence of the terrestrial biosphere on variations in atmospheric CO2.

Piper, S. C.

2001-12-01

77

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

78

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

79

Atmospheric NO2 dynamics and impact on ocean color retrievals in urban nearshore regions  

NASA Astrophysics Data System (ADS)

Urban nearshore regions are characterized by strong variability in atmospheric composition, associated with anthropogenic emissions and meteorological processes that influence the circulation and accumulation of atmospheric pollutants at the land-water interface. If not adequately corrected in satellite retrievals of ocean color, this atmospheric variability can impose a false impression of diurnal and seasonal changes in nearshore water quality and biogeochemical processes. Consideration of these errors is important for measurements from polar orbiting ocean color sensors but becomes critical for geostationary satellite missions having the capability for higher frequency and higher spatial resolution observations of coastal ocean dynamics. We examined variability in atmospheric NO2 over urban nearshore environments in the Eastern US, Europe, and Korea, using a new network of ground-based Pandora spectrometers and Aura-OMI satellite observations. Our measurements in the US and in Europe revealed clear diurnal and day-of-the-week patterns in total column NO2 (TCNO2), temporal changes as large as 0.8 DU within 4 h, and spatial variability as large as 0.7 DU within an area often covered by just a single OMI pixel. TCNO2 gradients were considerably stronger over the coastal cities of Korea. With a coarse resolution and an overpass at around 13:30 local time, OMI cannot detect this strong variability in NO2, missing pollution peaks from industrial and rush hour activities. Observations were combined with air quality model simulations and radiative transfer calculations to estimate the impact of atmospheric NO2 variability on satellite retrievals of coastal ocean remote sensing reflectance and biogeochemical variables (i.e., chlorophyll and CDOM).

Tzortziou, Maria; Herman, Jay R.; Ahmad, Ziauddin; Loughner, Christopher P.; Abuhassan, Nader; Cede, Alexander

2014-06-01

80

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

81

Simulated Global Atmospheric Dust Distribution: Sensitivity to Regional Topography, Geomorphology, and Hydrology  

E-print Network

Simulated Global Atmospheric Dust Distribution: Sensitivity to Regional Topography, Geomorphology for predicting future trends in dust production. We identify three related geomorphologic and hydrologic to regional surface geomorphology and runoff on large spatial scales. Satellite observations show

Zender, Charles

82

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

83

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

84

Regional Carbon Fluxes and Atmospheric Carbon Dynamics in the Southern Great Plains during the 2007 CLASIC intensive  

NASA Astrophysics Data System (ADS)

In June 2007, a regional campaign took place in the Southern Great Plains (SGP) to estimate land-atmosphere exchanges of CO2, water, and energy at 1 to 100 km scales. The primary goals of this campaign were to evaluate top-down and bottom-up estimates of regional fluxes and to understand the influence of moisture gradients, surface heterogeneity, and atmospheric transport patterns on these fluxes (and their estimation). The work was integrated with the Cloud and Land Surface Interaction Campaign (CLASIC), centered on the US DOE Atmospheric Radiation Measurement (ARM) Program SGP region. CO2 concentration data were collected from tower and airborne platforms. Eddy flux towers were deployed in the four major land cover types, distributed over the region's SE to NW precipitation gradient. In addition, CO2, water, and energy fluxes were observed with the Duke Helicopter Observation Platform (HOP) at various heights in the boundary layer, including in the surface layer (the few meters near the surface). One aircraft carried precise CO2, CO, and CH4 continuous measurement systems, and 14C, radon, and NOAA 12-flask (carbon cycle gases and isotopes) packages. Continuous CO2, CO, and radon concentrations, NOAA 2-flask package, and isotope diel flasks (14C, 13C, and 18O) were also collected from a centrally located 60 m tower. Flights were planned to constrain simple boundary layer budget models and to conduct Lagrangian air mass following experiments. We present these data in the context of characterizing surface carbon exchanges via bottom-up and top-down approaches. We also describe results from forward (using MM5-LSM) and inverse (using STILT) modeling to estimate regional surface carbon and energy fluxes. In addition to characterizing the influence of the land surface on the atmosphere, the aircraft data (in combination with observations of atmospheric dynamics) provides a very well characterized southern boundary condition to the NACP Mid-Continent Intensive.

Biraud, S. C.; Torn, M. S.; Riley, W. J.; Fischer, M. L.; Billesbach, D. P.; Avissar, R.; Berry, J. A.; Hirsch, A.; Loewenstein, M.; Lopez, J.

2007-12-01

85

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

86

External interannual ENSO forcing : which regions outside equatorial Pacific may influence the evolution of ENSO ?  

NASA Astrophysics Data System (ADS)

Low-frequency coupled ocean-atmosphere dynamics intrinsic to the Pacific Ocean are essential to El Niño development. Some recent studies (e.g Annamalai 2005, Izumo and al. 2010, Rodriguez-Fonseca 2009, Terray 2010, Vimont and al. 2003) however suggest that external interannual forcing may influence the evolution of El Niño. In the present study, we aim at identifying regions outside the Pacific Ocean, which can affect the evolution of ENSO. Our assumption is that zonal wind anomalies within the Pacific equatorial waveguide are a necessary condition to influence ENSO evolution. We thus aim at identifying teleconnections between SST anomalies outside of the equatorial Pacific, and Pacific equatorial zonal wind anomalies that are independent of ENSO. To that end, we first remove the ENSO signal from interannual wind and SST anomalies in several re-analyses by regression to all the principal components of an EOF analysis of Tropical Pacific Sea Surface Temperature which display significant correlations with Niño3.4 within 12 months of the ENSO peak. Results show that non-negligible (25% of interannual variance) ENSO-independent zonal winds anomalies remain in the western/central equatorial Pacific. We further show that SST anomalies in six regions (equatorial, northern and southern central Pacific; Tropical and southern Atlantic and southern Indian Ocean) display significant 0-3 months lead correlations to those ENSO-independent wind variations. These regions may hence influence ENSO evolution through remote influence on equatorial Pacific winds, as previously suggested by, e.g, Rodriguez-Fonseca (2009), Terray (2010), Vimont and al. (2003). While our statistical methodology did allow to isolate those regions, we still have to confirm from forced atmospheric and coupled simulations that: - SST anomalies in those regions can indeed influence zonal winds over the tropical Pacific, - the response of the Tropical Pacific coupled system to this external forcing can lead to an El Niño.

Dayan, H.; Vialard, J.; Izumo, T.; Lengaigne, M.; Terray, P.

2012-04-01

87

High frequency and wavenumber ocean-ice-atmosphere coupling in the Regional Arctic Climate Model  

NASA Astrophysics Data System (ADS)

We present results from the fully coupled version of the Regional Arctic Climate Model (RACM) on the spectral and noise characteristics of high-frequency (20-minute) dynamic coupling between the 9km Parallel Ocean Program/Community Ice Code (POP/CICE) and 50km Weather Research and Forecast model (WRF) using the CPL7 framework. We have employed an array of signal processing techniques to investigate: 1) Synchronization of the inertial response of POP and CICE to the passage of storms in WRF, and wavelet coherence of these results with in-situ observations of drift and deformation in the Arctic Ocean; 2) High-wavenumber signals in the sea ice deformation pattern resulting super-inertial coupling and aliasing of the wind field in CPL7, and the influence of these factors on the transmission of wind stress curl into the deep ocean; 3) The impact of high frequency ocean-ice-atmosphere coupling on the modeled sea ice thickness distribution. For this last set of experiments, we have run a set of winter band-limited integrations, filtering out high-frequency WRF inputs to the sea ice and ocean components. These experiments suggest the most pronounced regional influence of super-inertial coupling on sea ice mass extends from the Greenland Sea through Fram Strait to the North Pole, although there is also a significant basin-wide deformation pattern emanating from high spatiotemporal coupling in RACM.

Roberts, A.; Maslowski, W.; Jakacki, J.; Higgins, M.; Craig, T.; Cassano, J. J.; Gutowski, W. J.; Lettenmaier, D. P.

2011-12-01

88

Internal wave activity in the polar atmospheric regions during 2006 - 2009 revealed by COSMIC radio occultation data  

NASA Astrophysics Data System (ADS)

The satellite mission Formosat-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) consists of six micro-satellites, and each of them has four GPS-antennas. It was launched in April 2006, orbiting around the Earth at approximately 800 km. The primary scientific goal of the mission is to demonstrate the value of near-real-time radio occultation (RO) observations in improving operational numerical weather predictions (NWP). The goal is readily shown by assimilating the measurements of atmospheric parameters into used NWP-models. These parameters include density, temperature, pressure and relative humidity fields in the atmosphere. An analysis of their geographic and seasonal distributions is necessary to the understanding of the energy and momentum transfer and the reaction of the polar atmosphere in response to global warming. This task is especially important as the Polar Regions are very sensitive to the change in global temperature and it may be a major cause of global sea level rising. In this work, a statistical analysis of the internal gravity wave (IGW) activity in polar atmospheric regions (latitudes more than 60º) using Formosat-3/COSMIC RO temperature data collected from July 2006 to March 2009 has been performed. Geographic and seasonal distributions of the IGW potential energy (wave activity indicator) in the altitude interval from 15 to 35 km have been determined and analyzed. The obtained results show that the wave activity in the polar atmosphere is strong in winter and spring. The potential energy of IGWs in spring is largest in Antarctic atmospheric region, while it is largest in winter in Arctic region. The wave potential energy increases with altitude up to 35 km in the atmosphere of both Earth’s hemispheres. In Antarctic region, internal waves with high potential energy occur in the atmosphere over the Antarctic Peninsula. In Arctic region, a high wave activity is mainly observed over North Atlantic Ocean (Iceland) and Scandinavian Peninsula. In this work, the results of an analysis of the wave activity and factors influencing upon it in the polar stratosphere of Arctic and Antarctic have been presented and discussed. A statistical analysis of the IGW activity in Polar Regions (latitudes more than 60º) of the Earth’s atmosphere using Formosat-3/COSMIC RO temperature data collected from July 2006 to March 2009 is performed. Geographic and seasonal distributions of the IGW potential energy per unit mass (wave activity indicator) in the altitude interval from 15 to 35 km are determined and analyzed. This work was partially supported by the RFBR grant 13-02-00526-? and Program 22 of the RAS Presidium.

Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander; Liou, Yuei-An

89

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

90

Upwind convective influences on the isotopic composition of atmospheric water vapor over the tropical Andes  

NASA Astrophysics Data System (ADS)

We take advantage of the spatial coverage provided by the Tropospheric Emission Spectrometer on-board the Aura satellite to evaluate processes that control seasonal variations in atmospheric water vapor HDO/H2O values (?Dvapor) over the tropical Andes. ?Dvapor is lower in austral summer (December, January, and February, DJF) than austral winter (June, July, and August, JJA), which is broadly consistent with precipitation studies and with ?18Osnow preserved in tropical Andean glaciers. In DJF, 64% of ?Dvapor measurements over the tropical Andes are lower than predicted by Rayleigh distillation while 40% of JJA ?Dvapor measurements are lower than predicted by Rayleigh distillation. Air that has lower ?Dvapor than predicted by Rayleigh distillation at a given water vapor concentration (q) encounters low minimum outgoing longwave radiation (<240 W m-2) en route to the tropical Andes, suggesting convective intensity controls the isotopic ratios of these measurements. The broad regional coverage of the satellite data allows us to map the spatial extent of the region where isotopic ratios reflect convective processes in different seasons. In DJF, convection strongly influences ?Dvapor in the central tropical Andes. In JJA, convection influences ?Dvapor north of the tropical Andes. This pattern suggests that monsoon convection controls ?Dvapor in austral summer while large-scale advective mixing controls Andean ?Dvapor in austral winter.

Samuels-Crow, Kimberly E.; Galewsky, Joseph; Hardy, Douglas R.; Sharp, Zachary D.; Worden, John; Braun, Carsten

2014-06-01

91

Australian region tropical cyclones: Influence of environment at different scales  

NASA Astrophysics Data System (ADS)

This dissertation explores the influence of environmental factors on a variety of spatial and temporal scales on tropical cyclones (TCs) in the Australian region. Chapter 1 provides the motivation for the work presented, and leads into a discussion on the current state of knowledge of large-scale factors affecting the interannual variability of TCs in each of the seven global TC basins (Chapter 2). Chapter 3 is an investigation of the role of large-scale environmental factors, notably sea surface temperature (SST), low-level relative vorticity, and deep tropospheric vertical wind shear, for the interannual variability of November-April tropical TC activity in the Australian region. Extensive correlation analyses were carried out between TC frequency and intensity and the above-mentioned large-scale parameters, using TC data for 1970-2006 from the official Australian TC data set. Large correlations were found between the seasonal number of TCs and SST in the Nino 3.4 and Nino 4 regions. These correlations were greatest (-0.73) during the August-October period, immediately preceding the Australian TC season. The correlations remain almost unchanged for the July-September period and therefore can be viewed as potential seasonal predictors of the forthcoming TC season. In contrast, only weak correlations (<+0.37) were found with the local SST in the region north of Australia where many TCs originate; these were reduced almost to zero when the ENSO component of the SST was removed by partial correlation analysis. The annual frequency of TCs was strongly correlated with 850-hPa relative vorticity and vertical shear of the zonal wind over the main TC genesis areas of the Australian region. A Principal Component Analysis of the SST data set revealed two main modes of Pacific Ocean SST variability that match very closely with the basin-wide patterns of correlations between SST and TC frequencies. It was also found that the above-mentioned large correlations could be increased markedly (e.g. from -0.73 to -0.80 for the August-October period) by a weighted combination of SST time series from weakly correlated regions. When only the eastern region subset of the Australian TC data set was considered (Chapter 4), including the annual number of landfalling TCs in the northeastern state of Queensland, the correlations between TC number and ENSO decreased substantially. These correlations were reduced to less than +0.1 during the warm phase of Interdecadal Pacific Oscillation from 1979-1998, suggesting that the relationship between TC activity and ENSO fluctuates on interdecadal time scales. The number of landfalling TCs was highly correlated (+0.68) with total number of TCs forming in the eastern region each year. The interaction between complex terrain and a landfalling TC over northeastern Australia is investigated in Chapter 5 using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5). Severe TC Larry (March 2006) made landfall over an area of steep coastal orography and caused extensive damage. The damage pattern suggested that the mountainous terrain had a large influence on the TC wind field, with highly variable damage across relatively small distances. The major aims in this study were to reproduce the observed features of TC Larry, including track, intensity, speed of movement, size, decay rate, and the three-dimensional wind field, using realistic high-resolution terrain data and a nested grid with a horizontal spacing of 1 km for the finest domain (referred to as CTRL), and to assess how the above parameters change when the terrain height is set to zero (NOTOPOG). The TC track for CTRL, including the timing and location of landfall, was in close agreement with observation, with the model eye overlapping the location of the observed eye at landfall. Setting the terrain height to zero resulted in a more southerly track and a more intense storm at landfall. The orography in CTRL had a large impact on the TC's 3-D wind field, particularly in the boundary

Ramsay, Hamish Andrew

92

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 5.93 kg N ha(-1) yr(-1), respectively. The deposition of TN and total particulate N (TPN) was 18.02 and 4.33 kg N ha(-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

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 MODELING OF THE ATMOSPHERIC TRANSPORT AND DEPOSITION OF ATRAZINE  

EPA Science Inventory

A version of the Community Multiscale Air Quality (CMAQ) model has been developed by the U.S. EPA that is capable of addressing the atmospheric fate, transport and deposition of some common trace toxics. An initial, 36-km rectangular grid-cell application for atrazine has been...

95

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

96

Regional Atmospheric Modeling System Version 4.3/4.4  

E-print Network

, kinematic effects of terrain, cumulus convection, and sensible and latent heat exchange between the atmospheric model output with a variety of visualization software and other utilities. RAMS is most often used exchange boundary data between them. There is no lower limit to the domain size or to the mesh cell size

Gohm, Alexander

97

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

98

Influence of atmospheric turbulence on states of light carrying orbital angular momentum  

E-print Network

Influence of atmospheric turbulence on states of light carrying orbital angular momentum Brandon carrying orbital angular momentum (OAM) propagating through simulated atmospheric turbulence carrying orbital angular momentum (OAM). Allen et al. showed that beams with the profile of Ar expi carry

Boyd, Robert W.

99

The Influence of Soil Wetness on Near-Surface Atmospheric Variability  

Microsoft Academic Search

The influence of land surface processes on near-surface atmospheric variability on seasonal and interannual time scales is studied using output from two integrations of a general circulation model. In the first experiment of 50 years duration, soil moisture is predicted, thereby taking into consideration interactions between the surface moisture budget and the atmosphere. In the second experiment, of 25 years

Thomas Delworth; Syukuro Manabe

1989-01-01

100

Atmospheric influence on the interannual variability of the seasonal Diurnal Temperature Range over Europe  

Microsoft Academic Search

In this paper the relationship between the variability of the seasonal Diurnal Temperature Range (DTR) over Europe and the atmospheric circulation has been investigated. The spatiotemporal variability of the seasonal DTR over Europe and the influence of largescale atmospheric circulation on DTR have been examined by means of Empirical Orthogonal Function (EOF) analysis and composite map analysis. Based on the

M. Ionita; G. Lohmann; N. Rimbu

2011-01-01

101

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...

102

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

103

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

104

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

105

Influence of two atmospheric transport models on inferring sources and sinks of atmospheric CO2  

Microsoft Academic Search

Atmospheric transport models are a source of uncertainty in the diagnostics of the CO2 sources and sinks. We propose here a protocol to compare two transport models: a 2-dimensional (2D) and a 3-dimensional (3D) model, based on 3 different experiments that reveal the ability of each model to account for the different components of the atmospheric carbon cycle. The 2D

P. Bousquet; P. Ciais; P. Monfray; Y. Balkansk; M. Ramonet; P. Tans

1996-01-01

106

A regional coupled atmospheric-ocean model suitable for hydrological studies  

NASA Astrophysics Data System (ADS)

Comprehensive hydrological studies even on the regional scales (continent or sub-content size) should be addressed using coupled atmospheric-ocean model. This equally applies for the shorter time scale month-decadal and for regional climate studies. It would be desirable to have river routing sub model present also but we start with just ocean and atmosphere components (OC and AC in the further text). Recently Dr. Janjic has developed comprehensive multi-scale (in the space domain) atmospheric model. It is a sigma coordinate model on B-grid with comprehensive physics. Regarding the hydrological studies it should be mentioned its surface scheme that has multilayer structure (the specific setup depends on the processes examined). It models the snow and has variable number of layer in the snow cover itself. Model covers spatial scales of several hundreds of meters to global with very limited changes of its parameters. Actually the only change is in the treatment of moist processes (moist convection). It is a very efficient yet fully non-hydrostatic model and therefore very suitable for longer integrations. Another important characteristic that is trivial to transform it to full global model. Our ocean component for the time being is POM, The Princeton Ocean Model. Both components are written for use on parallel computers. In constriction of a coupled model spatial care should be taken in construction of coupler, part of the model through which information's are exchanged between AC and OC. In order to guaranty exact conservation of the exchange of energy we have divided each atmosphere grid cell into four ocean grid cells. Since AC is on the B-grid and OC is on the C-grid that was easy to achieve. Finally we present several integrations for different time scales for the Mediterranean domain, which was of special interest when we were designing the system. ACKNOWLEDGMENT This paper was realized as a part of the project "Studying climate change and its influence on the environment: impacts, adaptation and mitigation" (43007) financed by the Ministry of Education and Science of the Republic of Serbia within the framework of integrated and interdisciplinary research for the period 2011-2014.

Rajkovic, Bora; Djordjevic, Marija; Aresenovic, Pavle; Djurdjevic, Vladimir

2013-04-01

107

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.

108

Interannual variability in the atmospheric CO2 rectification over a boreal forest region  

NASA Astrophysics Data System (ADS)

Ecosystem CO2 exchange with the atmosphere 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 a coupled vertical diffusion scheme (VDS) and ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS), are used to investigate the interannual variability of the rectifier effect over a boreal forest region. The coupled model performed well (r2 = 0.70 and 0.87, at 40 m at hourly and daily time steps, respectively) in simulating CO2 vertical diffusion processes. The simulated annual atmospheric rectifier effect varies from 3.99 to 5.52 ppm, while the diurnal rectifying effect accounted for about a quarter of the annual total (22.8˜28.9%).The atmospheric rectification of CO2 is not simply influenced by terrestrial source and sink strengths, but by seasonal and diurnal variations in the land CO2 flux and their interaction with PBL dynamics. Air temperature and moisture are found to be the dominant climatic factors controlling the rectifier effect. The annual rectifier effect is highly correlated with annual mean temperature (r2 = 0.84), while annual mean air relative humidity can explain 51% of the interannual variation in rectification. Seasonal rectifier effect is also found to be more sensitive to climate variability than diurnal rectifier effect.

Chen, Baozhang; Chen, Jing M.; Worthy, Douglas E. J.

2005-08-01

109

Disentangling natural and anthropogenic sources of atmospheric sulfur in an industrial region using biomonitors.  

PubMed

Despite reductions in atmospheric sulfur (S) concentrations due to abatement policies in some countries, modeling the dispersion of this pollutant and disentangling anthropogenic sources from natural ones is still of great concern. Lichens have been used as biomonitors of the impacts of S for over 40 years, but their potential as source-tracers of specific sources, including natural ones, remains unexplored. In fact, few attempts have been made to try to distinguish and spatially model different sources of S using lichens. We have measured S concentrations and isotopic values in lichens within an industrial coastal region where different sources of S, natural and anthropogenic, interplay. We detected a prevailing influence of natural sea-originated S that mixed with anthropogenic sources of S. We were then able to disentangle the sources of S, by removing the ocean influence on S isotopic values, enabling us to model the impact of different anthropogenic sources on S deposition and highlighting the potential use of lichens to evaluate the weight of different types of anthropogenic sources. PMID:25607592

Barros, Ceres; Pinho, Pedro; Durão, Rita; Augusto, Sofia; Máguas, Cristina; Pereira, Maria João; Branquinho, Cristina

2015-02-17

110

Atmospheric profiles of CO? as integrators of regional scale exchange   

E-print Network

. The terrestrial biosphere is a key driver of climate and biogeochemical cycles at regional and global scales. Furthermore, the response of the Earth system to future drivers of climate change will depend on feedbacks between biogeochemistry and climate. Therefore...

Smallman, Thomas Luke

2014-06-30

111

Contrasting Regional Responses to Increasing Leaf-Level Atmospheric Carbon Dioxide over Australia  

E-print Network

Contrasting Regional Responses to Increasing Leaf-Level Atmospheric Carbon Dioxide over Australia, New South Wales, Australia JOHN L. MCGREGOR Centre for Australian Weather and Climate Research, and CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia JASON P. EVANS Climate Change

Evans, Jason

112

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

113

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

114

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

115

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

116

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

117

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

118

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

119

Ionospheric E-region electron density and neutral atmosphere variations  

NASA Technical Reports Server (NTRS)

Electron density deviations from a basic variation with the solar zenith angle were investigated. A model study was conducted in which the effects of changes in neutral and relative densities of atomic and molecular oxygen on calculated electron densities were compared with incoherent scatter measurements in the height range 100-117 km at Arecibo, Puerto Rico. The feasibility of determining tides in the neutral atmosphere from electron density profiles was studied. It was determined that variations in phase between the density and temperature variation and the comparable magnitudes of their components make it appear improbable that the useful information on tidal modes can be obtained in this way.

Stick, T. L.

1976-01-01

120

Influence of combustion atmospheres on the phase transformation of zirconia  

Microsoft Academic Search

This letter is concerned with the phase changes and changes in chemical composition in different combustion atmospheres at 700 to 900°C of a commercial partially stabilized ZrO2 material (designated ZN40, manufactured by Feldmfihle AG, Germany), with approximately 12 mol % MgO (Mg ZrO2). Observed low-temperature degradation of a commercial tetragonal stabilized ZrO2 material (manufactured by NTK, Japan) (Y ZrO2), with

A. K. Tjernlund; L. Hermansson; R. Carlsson; K. O. Axelsson

1986-01-01

121

Carbonaceous aerosols influencing atmospheric radiation: Black and organic carbon  

SciTech Connect

Carbonaceous particles in the atmosphere may both scatter and absorb solar radiation. The fraction associated with the absorbing component is generally referred to as black carbon (BC) and is mainly produced from incomplete combustion processes. The fraction associated with condensed organic compounds is generally referred to as organic carbon (OC) or organic matter and is mainly scattering. Absorption of solar radiation by carbonaceous aerosols may heat the atmosphere, thereby altering the vertical temperature profile, while scattering of solar radiation may lead to a net cooling of the atmosphere/ocean system. Carbonaceous aerosols may also enhance the concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the fine particle (D < 2.5 {mu}m) source rates of both OC and BC. The source rates for anthropogenic organic aerosols may be as large as the source rates for anthropogenic sulfate aerosols, suggesting a similar magnitude of direct forcing of climate. The role of BC in decreasing the amount of reflected solar radiation by OC and sulfates is discussed. The total estimated forcing depends on the source estimates for organic and black carbon aerosols which are highly uncertain. The role of organic aerosols acting as cloud condensation nuclei (CCN) is also described.

Penner, J.E. [Lawrence Livermore National Lab., CA (United States). Global Climate Research Div.

1994-09-01

122

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

123

Atmospheric winter conditions 2007/08 over the Arctic Ocean based on NP-35 data and regional model simulations  

NASA Astrophysics Data System (ADS)

Atmospheric measurements on the drifting Arctic sea ice station "North Pole-35" crossing the Eastern part of the Arctic Ocean during winter 2007/2008 have been compared with regional atmospheric HIRHAM model simulations. The observed near-surface temperature, mean sea level pressure and the vertical temperature, wind and humidity profiles are satisfactorily reproduced by the model. The strongest temperature differences between observations and the simulations occur near the surface due to an overestimated vertical mixing of heat in the stable Arctic boundary layer (ABL). The observations show very strong temperature inversions near the surface, whereas the simulated inversions occur frequently between the surface and 415 m at too high levels. The simulations are not able to reproduce the observed inversion strength. The regional model underestimates the wind speeds and the sharp vertical wind gradients. The strength of internal atmospheric dynamics on the temporal development of atmospheric surface variables and vertical profiles of temperature, wind and relative humidity has been examined. Although the HIRHAM model systematically overestimates relative humidity and produces too high long-wave downward radiation during winter, two different atmospheric circulation states, which are connected to higher or lower pressure systems over the Eastern part of the Arctic Ocean, are simulated in agreement with the NP-35 observations. Sensitivity studies with reduced vertical mixing of heat in the stable ABL have been carried out. A slower increase in the stability functions with decreasing Richardson number under stable stratification has an impact on the horizontal and vertical atmospheric structure. Changes in synoptical cyclones on time scales from 1-3 days over the North Atlantic cyclone path are generated, which influences the atmospheric baroclinic and planetary waves on time scales up to 20 days over the Arctic Ocean basin. The use of increased vertical stability in the model simulation leads to diminished planetary-scale variability over the Arctic Ocean.

Mielke, M.; Zinoviev, N. S.; Dethloff, K.; Rinke, A.; Kustov, V. J.; Makshtas, A. P.; Sokolov, V. T.; Neuber, R.; Maturilli, M.; Klaus, D.; Handorf, D.; Graeser, J.

2014-05-01

124

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

125

Tools for determining critical levels of atmospheric ammonia under the influence of multiple disturbances.  

PubMed

Critical levels (CLEs) of atmospheric ammonia based on biodiversity changes have been mostly calculated using small-scale single-source approaches, to avoid interference by other factors, which also influence biodiversity. Thus, it is questionable whether these CLEs are valid at larger spatial scales, in a multi- disturbances context. To test so, we sampled lichen diversity and ammonia at 80 sites across a region with a complex land-cover including industrial and urban areas. At a regional scale, confounding factors such as industrial pollutants prevailed, masking the CLEs. We propose and use a new tool to calculate CLEs by stratifying ammonia concentrations into classes, and focusing on the highest diversity values. Based on the significant correlations between ammonia and biodiversity, we found the CLE of ammonia for Mediterranean evergreen woodlands to be 0.69 ?g m(-3), below the previously accepted value of 1.9 ?g m(-3), and below the currently accepted pan-European CLE of 1.0 ?g m(-3). PMID:24568792

Pinho, P; Llop, E; Ribeiro, M C; Cruz, C; Soares, A; Pereira, M J; Branquinho, C

2014-05-01

126

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

127

Influence of interplanetary trajectory selection on Mars atmospheric entry velocity  

NASA Astrophysics Data System (ADS)

Many current manned Mars mission studies are using low lift-to-drag ratio (L/D) vehicles to aerobrake at both Mars and Earth. The use of these low L/D vehicles could limit the allowable velocity at the atmospheric interface. This paper will demonstrate that if entry velocity constraints are incorporated into the interplanetary analysis of aerobraking Mars missions, many opportunities can be achieved for a small increase in initial mass in low-Earth orbit (IMLEO). These opportunities result from varying the initial launch date and the encounter dates and possibly using a powered Venus swingby on either the inbound or outbound transfer. This paper demonstrates this technique by using three atmospheric entry velocity ranges at Mars arrival (6.0-8.5, 6.4-8.1, and 7.2-7.3 km/s), unconstrained Mars entry velocities, and an Earth return entry velocity below 14 km/s. The results indicate that, by carefully selecting the interplanetary trajectory, an optimum IMLEO mission can be found for even highly restrictive entry velocity missions in practically all of the 15 yr studied.

Striepe, Scott A.; Braun, Robert D.; Powell, Richard W.; Fowler, Wallace T.

1993-08-01

128

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

129

Atmospheric and oceanic influences on the winter and spring Miño river flow  

NASA Astrophysics Data System (ADS)

We examine the climatic mechanisms associated to Miño streamflow anomalies during winter and spring, exploring the relationships between the streamflow and several atmospheric teleconnections patterns and seasonal sea level pressure and sea surface temperature (SST) for the previous and simultaneous seasons. The Miño river basin is located in the Northwestern Iberian Peninsula. It covers a limited territory, bordered by the Atlantic Ocean and Cantabric Sea. The data base of streamflows comprises montlhy data form 19 stations, covering the period from October 1956 to September 2007. We have performed a Principal Component Analysis of these monthly data, finding only one significant PC with a associated variance of 86%. Following the approach adopted by other authors, in a first step we try to identify teleconnections patterns and sectors of oceanic SST and SLP anomalies that can be related with Miño's river flow. In order to do that we have evaluated the point linear correlation between the winter and spring streamflow PC series and the teleconnections indices, the Northern Hemisphere SLP and the global SST anomalies from simultaneous previous seasons. Teleconnections and regions showing significant correlations are identified as potential explanatory mechanisms, or even predictors. The second step is to identify, among these selected teleconnections and regions, those that can be considered as stable. This is achieved through the analysis of the variability of the correlation between winter and spring Miño flow anomalies and potential explanatory variables using a moving window of 20 years. The correlation is considered to be stable for those regions where spring streamflow and explanatory variables are significantly correlated at 90% level (r = 0.36) for more than 80% of the 20-year windows covering the period 1956-2007 and, furthermore, that the sign of the correlation does not change with time. Teleconnections and regions verifying this criterion are considered as robust explanatory variables and predictors, which could be used in a multiple linear regression model for the Miño streamflow. The preliminary results show that winter Miño streamflow are more dominated by contemporary NAO, EA, and SCA teleconnections and also by the SLP anomalies over Iberian and Scandinavian Peninsula and Northeastern Canada. On the other hand, for the spring stream flow, there is also a remarkable influence of the contemporary SCA, but also an influence on previous winter SLP anomalies on the Northeastern Canada and with previous winter SST anomalies of the region El Niño3. These variables will be used as explanatory variables for the spring Miño river flow in a model based on linear regression. Acknowledgments: The Spanish Ministry of Science and Innovation, with additional support from the European Community Funds (FEDER), project CGL2007-61151/CLI, has financed this study.

Esteban-Parra, M. J.; Gámiz-Fortis, S. R.; Argüeso, D.; Hidalgo-Muñoz, J. M.; Calandria, D.; Castro-Díez, Y.

2010-09-01

130

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

NASA Astrophysics Data System (ADS)

In 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

131

Atmospheric Extreme Events in the North Atlantic Region  

NASA Astrophysics Data System (ADS)

An important part of European weather and climate are storms. European winter storms cause economic damage and insurance losses on the order of billions of Euro per year. European winter storms rank as the second highest cause of global natural catastrophe insurance loss. Many of these hazard events are not independent; for instance, severe storms can occur in trains of storms. Recent examples of such subsequently occurring storms include January 2008 (Paula and Resi) and March 2008 (Emma, Johanna and Kirsten). Each of these trains of storms caused damages on the order of ~€1bn. Extreme value statistics are based on the premise that extreme events are iid but this is rarely the case in natural systems where extreme events tend to cluster. Thus, no account is taken of memory and correlation that characterise many natural time series; this fundamentally limits our ability to forecast and to estimate return periods of extreme events. In my presentation I will discuss two possible causes of this clustering: (i) The propensity of extreme events to depend on large-scale circulation regimes and (ii) the long-range correlation properties of surface windspeeds enhances the likelihood of extreme events to cluster. These two characteristics affect the return periods of atmospheric extreme events and thus insurance pricing.

Franzke, C.

2012-04-01

132

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 2014 23:18:06 #12;Influence of Penning effect on the plasma features in a non-equilibrium atmospheric various innovative applications. The influence of Penning effect on the formation, propagation, and other

Zexian, Cao

133

Influence of climatic factors on the past atmospheric content of the C-14 isotope  

NASA Astrophysics Data System (ADS)

Reconstructions of solar activity in the past epochs based on information on the past atmospheric content of the cosmogenic 14C isotope are nowadays actively discussed. The 14C isotope is generated in the atmosphere of the Earth under the influence of cosmic rays, and its concentration in annual tree rings carries information on the past solar activity. However, the concentration of this isotope in annual tree rings may also be influenced by climatic factors. In the present work, the possible correlation between variations in the 14C atmospheric content and in the Earth's global temperature from the late 14th century to the middle of the 19th century is studied. It is shown that variations in global temperature may produce changes in the 14C atmospheric content and consequently have to be taken into account in reconstructions of the past solar activity.

Kudryavtsev, I. V.; Dergachev, V. A.; Nagovitsyn, Yu. A.; Ogurtsov, M. G.; Jungner, H.

2013-12-01

134

Influence of solar magnetic sector structure on terrestrial atmosphere vorticity  

NASA Technical Reports Server (NTRS)

The solar magnetic sector structure has a sizable and reproducible influence on tropospheric and lower stratospheric vorticity. The average vorticity during winter in the Northhern Hemisphere north of 20 deg N latitude reaches a minimum approximately one day after the passing of a sector boundary, and then increases during the following two or three days. The effect is found at all heights within the troposphere, but is not prominent in the stratosphere, except at the lower levels. No single longitudinal interval appears to dominate the effect.

Wilcox, J. M.; Scherrer, P. H.; Svalgaard, L.; Roberts, W. O.; Olson, R. H.; Jenne, R. L.

1973-01-01

135

Regional Carbon Fluxes and Atmospheric Carbon Dynamics in the Southern Great Plains during the 2007 Mid Continent Intensive of NACP  

NASA Astrophysics Data System (ADS)

In June 2007, an intensive regional campaign will take place in the Southern Great Plains (SGP) to estimate land-atmosphere exchanges of CO2, water, and energy at 1 to 100 km scales. The primary goals of this North American Carbon Program (NACP) campaign are to evaluate top-down and bottom-up estimates of regional fluxes and to understand the influence of moisture gradients, surface heterogeneity, and atmospheric transport patterns on these fluxes (and their estimation). The work will be integrated with the Cloud and Land Surface Interaction Campaign (CLASIC), centered on the US DOE Atmospheric Radiation Measurement Program SGP region. CLASIC will focus on interactions among the land surface, convective boundary layer, and cumulus clouds, and will utilize an array of atmospheric measurements. Carbon and meteorological data streams and logistical resources will be available to other NACP researchers. Carbon flux and concentration data will be collected from tower and airborne platforms. Eddy flux towers will be deployed in the four major land cover types, distributed over the region's SE to NW precipitation gradient. In addition, CO2, water, and energy fluxes will be observed with the Duke Helicopter Observation Platform (HOP) at various heights in the boundary layer, including in the surface layer (the few meters near the surface). Two aircraft will carry precise CO2 measurement systems and NOAA12-flask packages for carbon cycle gases and isotopes. Continuous CO2 and CO concentrations, NOAA flasks, and isotope diel flasks (14C, 13C, and 18O) will also be collected from a centrally located 60 m tower. Flights are planned to constrain simple boundary layer budget models and to conduct Lagrangian air mass following experiments. A distributed model of land surface fluxes will be run off line and coupled to MM5 with tracer capability. In addition to characterizing the influence of the land surface on the atmosphere, the aircraft data (in combination with observations of atmospheric dynamics) will provide a very well characterized southern boundary condition to the Mid-Continent Intensive.

Torn, M. S.; Fischer, M. L.; Riley, W. J.; Jackson, T. J.; Avissar, R.; Biraud, S. C.; Billesbach, D. P.; Sweeney, C.; Tans, P. P.; Berry, J. A.

2006-12-01

136

Influence of parameters of modifying oxygen-containing atmosphere on oxynitriding of titanium alloys  

Microsoft Academic Search

We study the influence of the parameters of modifying oxygen-containing atmosphere (the degree of rarefaction, temperature\\u000a and time of modification) on the oxynitriding of titanium alloys. It is shown that, as the degree of rarefaction of the atmosphere\\u000a increases and the temperature of modification decreases, the process of phase formation on the surface of titanium alloys\\u000a evolves in the direction

I. M. Pohrelyuk; V. M. Fedirko; O. I. Yas’kiv; Dong-Bok Lee; O. V. Tkachuk

2009-01-01

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 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

139

Transformations of long-living and short-living gaseous pollutants in the atmosphere of urban regions  

NASA Astrophysics Data System (ADS)

The research was devoted to the problem of estimation of chemical transformations of source species and atmospheric species in high-polluted areas. Box Air Quality Model (BAQM offline) was developed to estimate degree of influence of different species on atmospheric processes by analysis of chemical transformation and consequently lifetimes of these species, i.e. how long a representative molecule of the substance will stay in the atmosphere before it is chemically removed. Preliminary study of chemical mechanisms of Global and Regional weather forecast models with chemical branch (Enviro-HIRLAM, WRF, ALADIN, ECMWF GEMS) helped to develop a universal chemical mechanism for BAQM. The new mechanism describes chemical reaction pathways for the troposphere and lower stratosphere and can be implemented at regional and global scales. The mechanism was developed using lumping technique on the basis of RACM mechanism. Aggregation of primary species into lumped species is based on their reactivities and emission rates. The different chemical solvents were used to simulate change of production and destruction. As initial conditions BAQM considers both biogenic and anthropogenic emissions. Lifetime calculations show that "long-living" gases demand special attention since make the greatest impact on global atmospheric processes. Such species well mix in the atmosphere and can transport for long distances from the source of emissions. "Short-living" species can affect regional processes especially in the urban polluted areas where concentration of polluted species is high. So, in such regions (large cities, industrial areas, megacities) there are high concentrations of O3, NOx, but air quality depends on distribution of these concentrations in observing region. According to the simulations we define "long-living" species: SO2, N2, CH4, CO, H2, H2O (above 70hPa), H2O2, HCl and "short-living" species: O3, O(3P), O(1D), H2, HNO3, OH, HO2, CH3, CH3O2, CH3OOH, N, NO, NO2, NO3, Cl, Br2, BrO Some gases such as NOx can be short-living and long-living simultaneously. Its behavior depends on different atmospheric conditions, concentrations of other gases such as OH and O3, time of the day or model domain. It should be taken into account at chemical modeling to define which species will dominate in horizontal or vertical transport. The BAQM model confirms strong dependence of O3 on HOx. It is happened because each O3 molecule crossing the tropopause can yield at most two OH molecules in the troposphere. However, the concentrations and lifetimes depend on period of the day also. There isn't any production or loss due to photolysis reactions at night, but at daytime the photolysis plays an important role. The larger hydrocarbons have smaller global sources than CH4 and are therefore less important than CH4 for global tropospheric chemistry. They are however critical for rapid production of O3 in polluted regions, and play also an important role in the long-range transport of NOx. Hence, chemical feedbacks are very important mechanisms in the atmosphere of urban areas. Since the amount of chemically active species in the atmosphere increase due to emissions from the surface layer the conditions for chemical transformations in the upper troposphere change. Consequently, the emissions of chemically active species from polluted surface areas to the atmosphere increase (positive feedback) or the emission of chemically active species to the atmosphere decrease (negative feedback). Box Air Quality Model can be coupled with regional or global atmospheric models as a chemical module.

Filippenko, Anna; Smyshlyaev, Sergey

2010-05-01

140

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

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

Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions. Part 2; The Americas  

NASA Technical Reports Server (NTRS)

Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4) general circulation model (GCM) to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively). Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982 1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern America, an increase in precipitation over Central America and the Caribbean, and an enhancement of convergence in the North American monsoon region.

Wilcox, E. M.; Sud, Y. C.; Walker, G.

2009-01-01

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

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

145

Influence of atmospheric stability on wind-turbine wakes: A large-eddy simulation study  

NASA Astrophysics Data System (ADS)

In this study, large-eddy simulation is combined with a turbine model to investigate the influence of atmospheric thermal stability on wind-turbine wakes. The simulation results show that atmospheric stability has a significant effect on the spatial distribution of the mean velocity deficit and turbulence statistics in the wake region as well as the wake meandering characteristics downwind of the turbine. In particular, the enhanced turbulence level associated with positive buoyancy under the convective condition leads to a relatively larger flow entrainment and, thus, a faster wake recovery. For the particular cases considered in this study, the growth rate of the wake is about 2.4 times larger for the convective case than for the stable one. Consistent with this result, for a given distance downwind of the turbine, wake meandering is also stronger under the convective condition compared with the neutral and stable cases. It is also shown that, for all the stability cases, the growth rate of the wake and wake meandering in the vertical direction is smaller compared with the ones in the lateral direction. This is mainly related to the different turbulence levels of the incoming wind in the different directions, together with the anisotropy imposed by the presence of the ground. It is also found that the wake velocity deficit is well characterized by a modified version of a recently proposed analytical model that is based on mass and momentum conservation and the assumption of a self-similar Gaussian distribution of the velocity deficit. Specifically, using a two-dimensional elliptical (instead of axisymmetric) Gaussian distribution allows to account for the different lateral and vertical growth rates, particularly in the convective case, where the non-axisymmetry of the wake is stronger. Detailed analysis of the resolved turbulent kinetic energy budget in the wake reveals also that thermal stratification considerably affects the magnitude and spatial distribution of the turbulence production, dissipation, and transport terms.

Abkar, Mahdi; Porté-Agel, Fernando

2015-03-01

146

Large gradients in aerosol induced atmospheric heating rate over oceanic regions around India: Results from the ICARB Experiment of ISRO-GBP  

NASA Astrophysics Data System (ADS)

The importance of aerosol absorption and the resulting heating of the lower atmosphere over south Asia are being increasingly investigated in the context of regional and global climate implications. Even though significant abundance of absorbing aerosols has been measured over the oceanic regions around India, studies addressing its spatial and vertical distributions and radiative impacts are sparse. Most of the regional-climate impacts assessments are mainly based on the Indian Ocean Experiment (INDOEX) data or using the chemical transport model simulations. In the backdrop of the regional climate implications of absorbing aerosols, exten-sive, spatially resolved measurements of aerosol microphysical properties were made onboard research ship and aircraft during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) as a part of ISRO -Geosphere Biosphere Program. Aerosol parameters within the marine atmospheric boundary layer (MABL), free troposphere and in the entire column clearly depict large gradient along the latitudes and longitudes. Using these concurrent measurements of the aerosol properties, atmospheric radiative forcing and heating rates were estimated for a spatial resolution of 1 by 1. The spatial distribution of aerosol heating rate showed very high ( 0.5 K day per day) values over the northern Bay of Bengal and very low (¡ 0.1 K per day) values over the southeastern Arabian Sea. Similarly, aircraft measurements also showed an increase in the amplitude and strength of the elevated aerosol layers from south to north direction. Very high values of heating rate above the MABL modifies the thermody-namics structure of the atmosphere, which influence the stability of the lower troposphere and thus the hydrological cycle over the region. These gradients in atmospheric heating induced by aerosols will significantly influence the synoptic circulations over the regions when the winds are in transition from northeasterly to southwesterly over the oceanic regions around India. There-fore authors hypothesis that, this heating gradient would strengthen the circulation pattern and dynamically influence the monsoon precipitation. Details will be presented.

Babu, S. Suresh; Krishna Moorthy, K.; Nair, Vijayakumar S.; K, Satheesh S.

147

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

148

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.

2015-03-01

149

Influence of atmospheric boundary layer on turbulence in wind turbine wake  

NASA Astrophysics Data System (ADS)

Full-scale wind turbines (WT) operate in the atmospheric boundary layer. The atmospheric boundary layer structure significantly influences the turbulence generated in the wake of the WT. As Atmospheric boundary layer structure is dictated by the stratification of the atmosphere, hence stratifications effects are critical in accurate representation of the turbine wake physics. Due to the dependency of several factors, such as turbulence scales, buoyancy flux, momentum flux, the atmospheric boundary layer turbulence capturing is really challenging. Large Eddy Simulation (LES) has been used as a tool to understand the effects of atmospheric stability on turbine wake turbulence. The differences between the stable and unstable atmosphere on wake of 5-MW turbine has been explored. Differences in tip and root vortex interactions, wake expansion and recovery have been analyzed. The study has revealed for stable ABL low level jets play an important role in wake dynamics and increasing stability delays the wake recovery. Tip vortex is unconditionally unstable in all stability conditions due to mutual inductance mode of stability leading to vortex merging. The study is one of the first studies that accounts for realistic atmospheric boundary turbulence on wake development.

Debnath, Mithu Chandra

150

Author's personal copy Pollution influences on atmospheric composition and chemistry at high  

E-print Network

Author's personal copy Pollution influences on atmospheric composition and chemistry at high, Hampton, VA, USA c Pennsylvania State University, University Park, PA, USA d California Environmental Received in revised form 5 August 2010 Accepted 11 August 2010 Keywords: Arctic pollution Ozone Aerosols

Jimenez, Jose-Luis

151

Influence of Elevated Atmospheric Carbon Dioxide on Transcriptional Responses of Bradyrhizobium japonicum in the Soybean Rhizoplane  

PubMed Central

Elevated atmospheric CO2 can influence the structure and function of rhizoplane and rhizosphere microorganisms by altering root growth and the quality and quantity of compounds released into the rhizoplane and rhizosphere via root exudation. In these studies we investigated the transcriptional responses of Bradyrhizobium japonicum cells growing in the rhizoplane of soybean plants exposed to elevated atmospheric CO2. The results of microarray analyses indicated that elevated atmospheric CO2 concentration indirectly influenced the expression of a large number of genes in Bradyrhizobium attached to soybean roots. In addition, relative to plants and bacteria grown under ambient CO2 growth conditions, genes involved in C1 metabolism, denitrification and FixK2-associated genes, including those involved in nitrogen fixation, microaerobic respiration, respiratory nitrite reductase, and heme biosynthesis, were significantly up-regulated under conditions of elevated CO2 in the rhizosphere. The expression profile of genes involved in lipochitooligosaccharide Nod factor biosynthesis and negative transcriptional regulators of nodulation genes, nolA and nodD2, were also influenced by plant growth under conditions of elevated CO2. Taken together, the results of these studies indicate that the growth of soybeans under conditions of elevated atmospheric CO2 influences gene expressions in B. japonicum in the soybean rhizoplane, resulting in changes to carbon/nitrogen metabolism, respiration, and nodulation efficiency. PMID:23666536

Sugawara, Masayuki; Sadowsky, Michael J.

2013-01-01

152

The Young Sun and Its Influence on Planetary Atmospheres M. Gdel1,2  

E-print Network

-studied "Sun in Time" sample covering ages of 100-7000 Myr in the optical, ultraviolet (UV), far Stellar evolution calculations indicate that the young, zero-age main sequence Sun was bolometricallyThe Young Sun and Its Influence on Planetary Atmospheres M. Güdel1,2 , J.F. Kasting3 1 ETH Zurich

Guedel, Manuel

153

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

154

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

155

Synoptic scale study of the Arctic polar vortex's influence on the middle atmosphere, 1, Observations  

E-print Network

Synoptic scale study of the Arctic polar vortex's influence on the middle atmosphere, 1 a period of days to weeks that can be attributed to movement and interaction of the polar vortex of the polar vortex and Aleutian High. All of these synoptic scale measurements indicate a change in the local

Duck, Thomas J.

156

Local and regional factors influence the structure of treehole metacommunities  

PubMed Central

Background Abiotic and biotic factors in a local habitat may strongly impact the community residing within, but spatially structured metacommunities are also influenced by regional factors such as immigration and colonization. We used three years of monthly treehole census data to evaluate the relative influence of local and regional factors on our study system. Results Every species responded to at least one of three local environmental factors measured: water volume, leaf litter mass, and presence of a top predator. Several species were affected by water volume, and a non-exclusive group of species were influenced by leaf litter mass. Relative abundance of Aedes triseriatus was higher in treeholes with higher volumes of water, and relative abundances of three out of six other species were lower in treeholes with higher volumes of water. Leaf litter mass positively affected densities of Aedes triseriatus and relative abundance of several dipteran species. The density of the top predator, Toxorhynchites rutilus, affected the relative abundance of the two most common species, A. triseriatus and Culicoides guttipennis. Treeholes with T. rutilus had an average of two more species than treeholes without T. rutilus. We found little evidence of synchrony between pairs of treeholes, either spatially or temporally. There were high levels of spatial and temporal turnover, and spatial turnover increased with distance between patches. Conclusion The strong effects of water volume, leaf litter mass, and presence of a top predator, along with the high temporal turnover strongly suggest that species presence and density are determined by local factors and changes in those factors over time. Both low water volume and high predator densities can eliminate populations in local patches, and those populations can recolonize patches when rain refills or predators exit treeholes. Population densities of the same species were not matched between pairs of treeholes, suggesting variation in local factors and limited dispersal. Distance effects on spatial turnover also support limitations to dispersal in the metacommunity, and we conclude that the weight of evidence favors a strong influence of local factors relative to regional factors. PMID:19099587

Paradise, Christopher J; Blue, Jarrod D; Burkhart, John Q; Goldberg, Justin; Harshaw, Lauren; Hawkins, Katherine D; Kegan, Benjamin; Krentz, Tyler; Smith, Leslie; Villalpando, Shawn

2008-01-01

157

Influence of atmospheric properties on detection of wood-warbler nocturnal flight calls  

NASA Astrophysics Data System (ADS)

Avian migration monitoring can take on many forms; however, monitoring active nocturnal migration of land birds is limited to a few techniques. Avian nocturnal flight calls are currently the only method for describing migrant composition at the species level. However, as this method develops, more information is needed to understand the sources of variation in call detection. Additionally, few studies examine how detection probabilities differ under varying atmospheric conditions. We use nocturnal flight call recordings from captive individuals to explore the dependence of flight call detection on atmospheric temperature and humidity. Height or distance from origin had the largest influence on call detection, while temperature and humidity also influenced detectability at higher altitudes. Because flight call detection varies with both atmospheric conditions and flight height, improved monitoring across time and space will require correction for these factors to generate standardized metrics of songbird migration.

Horton, Kyle G.; Stepanian, Phillip M.; Wainwright, Charlotte E.; Tegeler, Amy K.

2015-01-01

158

Some peculiarities of the upper atmosphere planetary scale motions in the Caucasus region  

NASA Astrophysics Data System (ADS)

The presence of variations characteristic for planetary scale motion in the Earth's upper atmosphere is shown in the intensities of the nightglow mesopause hydroxyl OH(8-3) band, the lower thermosphere oxygen green OI 557.7nm line and the ionosphere F2 region red OI 630.0 nm line, observed from Abastumani(41.75N, 42.82E). It is demonstrated that the simultaneous observations of the mentioned intensities are characterized by vertical propagation of 4-8 hour tidal motions, which is considered as the manifestation of the lower and upper atmosphere-ionosphere dynamical coupling in the Caucasus region.

Gudadze, Nikoloz; Javakhishvili, Giorgi; Didebulidze, Goderdzi

2014-12-01

159

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

160

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

161

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

162

Organochlorine pesticides in the atmosphere of Guangzhou and Hong Kong: Regional sources and long-range atmospheric transport  

NASA Astrophysics Data System (ADS)

Organochlorine pesticides (OCPs) were measured in the atmosphere over the period of December 2003-December 2004 at four sampling sites in Guangzhou and Hong Kong. Gas phase and particle phase concentrations of 8 OCP species, including trans-chlordane ( t-CHL), cis-chlordane ( c-CHL), p, p'-DDT, p, p'-DDE, o, p'-DDT, ?-endosulfan, ?- and ?-hexachlorocyclohexane (HCH), were studied. OCPs were found predominantly in the gas phase in all seasons. t-CHL, c-CHL, o, p'-DDT, p, p'-DDT and ?-endosulfan had significantly ( p<0.001) higher concentrations than other OCPs, with mean values (gas+particle) typically ranging from 103 to 1440 pg m -3. In general, the concentrations of OCPs in summer were higher than that in winter, except for ?-HCH which showed no clear seasonal pattern. Higher levels of ?-HCH and o, p'-DDT found in Guangzhou could be attributed to the present usage of lindane and dicofol in the Pearl River Delta (PRD) region. The very high concentrations of p, p'-DDT and ?-endosulfan were observed at all sampling sites. The results of 7 days air back trajectory analysis indicated that the unusual high p, p'-DDT levels in summer in both cities could be related to the seasonal usage of DDT containing antifouling paints for fishing ships in the upwind seaports of the region. The high concentrations of ?-endosulfan in winter in the study area suggested an atmospheric transport by the winter monsoon from the East China, where endosulfan is being used as insecticide in cotton fields. The consistency of the seasonal variation of concentrations and isomeric ratios of DDTs and ?-endosulfan with the alternation of winter monsoon and summer monsoon suggested that the Asian monsoon plays an important role in the long-range atmospheric transport of OCPs.

Li, Jun; Zhang, Gan; Guo, Lingli; Xu, Weihai; Li, Xiangdong; Lee, Celine S. L.; Ding, Aijun; Wang, Tao

163

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

164

REPRESENTATION OF ATMOSPHERIC MOTION IN MODELS OF REGIONAL-SCALE AIR POLLUTION  

EPA Science Inventory

A method is developed for generating ensembles of wind fields for use in regional scale (1000 km) models of transport and diffusion. The underlying objective is a methodology for representing atmospheric motion in applied air pollution models that permits explicit treatment of th...

165

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

166

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

167

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

168

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

169

Influence of solar-probe inherent atmosphere on in-situ observations  

SciTech Connect

The solar corona is the source of the solar wind, which is responsible for the heliosphere and plays a crucial role in solar/terrestrial phenomena. A comprehensive understanding of these phenomena can be established only by directly measuring ion and electron velocity distributions, plasma waves, and fluxes of energetic particles near the sun. The problem resulting from the inherent atmosphere of a spacecraft moving in the vicinity of the sun and the influence of this atmosphere on in-situ measurements of the solar corona plasma is key to the realization and success of any solar probe mission. To evaluate the influence of the probe-inherent atmosphere on in-situ observations, the authors have developed comprehensive radiation hydrodynamic models. The physics of plasma/probe/vapor interaction are also being developed in a self-consistent model to predict the effect of probe inherent atmosphere on in-situ measurements of corona parameters during solar flares. Interaction of the ionized atmosphere with the ambient natural plasma will create a turbulent shock wave that can affect in-situ measurements and must be taken into account in designing the spacecraft and its scientific components.

Hassanein, A. [Argonne National Lab., IL (United States); Konkashbaev, A.I.; Konkashbaev, I.K.; Nikandrov, L.B. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation)

1998-08-01

170

Recent sediment dynamics in the region of Mekong water influence  

NASA Astrophysics Data System (ADS)

The recent fine sediment dynamics in the region of fresh water influence (ROFI) off the Mekong River are subject of this study. Each year about 160 t of sediment discharges from the river and disperses over the shelf. The typical tropical monsoon regime induces the pronounced seasonal cycle of the discharge of water and sediment. This cycle is reflected in rates of erosion and deposition on the shelf. The modern hypothesis says that this cycle of sediment results in deposition of sediment on the shelf during the high flow season and the transport back into the river mouth during the low flow season. A coupled hydrodynamic-wind-wave and sediment model, which simulates the seasonal cycle of the system, is used to prove this hypothesis.

Hein, Hartmut; Hein, Birte; Pohlmann, Thomas

2013-11-01

171

Long-range atmospheric transport of heavy metals from industrial regions of Ural and Norilsk to siberian environment  

NASA Astrophysics Data System (ADS)

The main idea of the work is to analyze atmospheric transport of heavy metals (Ni, Cu, Pb) from the industries of the region of Norilsk, and the Ural over the territory of Siberia. The basic data were 5-days air mass trajectories from the sources calculated for every day of January, April, July, and October during 28 years from 1981 to 2008. NCEP/NCAR Reanalysis Data Files and HYSPLIT 4 model were used. Spatial, seasonal and long-term variations in heavy metal (HM) concentrations in surface air and precipitations, as well as in fluxes of these elements onto the surface were studied. The obtained results (presented as maps) may be used as assessment of anthropogenic influence of the sources under investigation on the environment of remote and hard-to-reach areas. The HM air concentrations and fluxes onto the surface depend on surface properties and precipitation regime, and experience great seasonal and spatial variations. The maximal air concentrations are in cold seasons, whereas the maximal fluxes onto the surface occur in warm period. In comparison anthropogenic loadings at different places the cleanest air does not guarantees the minimal vertical fluxes. The pollution trends (modulo) caused only by the transformation of air circulation processes are quite comparable with the contributions of source-emissions' changes. The main result is the decreasing of Siberian environment pollution through the atmosphere from regarded sources during the last years. At a distance about 2000 km from a large source under investigation its atmospheric emissions form only the background levels of HM in the surface environment, and the real pollution levels are determined by local anthropogenic sources (with less emissions) if they exist. So, for the Lake Baikal the HM inputs from our distant sources through atmosphere to the water surface are insignificant in comparison with the flowing rivers' ones, and lake water pollution occurs mainly due to rivers' pollution. However, annual HM fluxes from Ural and Norilsk regions through atmosphere on the territories of basins of large Siberian Rivers - Ob, Yenisei or Lena - are quite comparable with HM's fluxes carrying away in river's water to the Arctic Ocean. Thus, the long-range atmospheric transport of heavy metals from Ural and Norilsk regions must be taken into account as one of the processes forming compositions of surface water objects and soils, as well as of food chains in different ecosystems of Siberia.

Vinogradova, Anna; Maksimenkov, Leonid; Pogarskii, Fedor

2010-05-01

172

An Aerosol Scheme Which Includes Sesquiterpenes for the Regional Atmospheric Chemistry Mechanism, Version 2  

NASA Astrophysics Data System (ADS)

Sesquiterpenes, a class of biogenic hydrocarbons made up of three isoprene units (C15H24), participate in aerosol formation and growth processes. Field measurements of sesquiterpenes, as well as laboratory studies of reactions of sesquiterpenes and their products (gas phase and particulate phase), are just now becoming available. Several recent studies have employed a mixture of models and measurements to suggest that current estimates of biogenic hydrocarbon production by forests are low (Di Carlo et al., 2004; Goldstien et al., 2004) and the subsequent chemical processes due to this class of compounds are underestimated. Timely development of models to include reactions involving sesquiterpenes is crucial for evaluating their impact on aerosol formation and growth since field measurements have proven technically challenging. In this work we are introducing a chemical scheme into the new Regional Atmospheric Chemistry Mechanism, Version 2 (RACM2) (Goliff, Stockwell et al., 2006, in preparation) which treats the chemical processing of sesquiterpenes, as well as other organics that have been shown to produce aerosols (e.g., xylenes and monoterpenes), to form both gas phase and particulate phase products. This work is in conjunction with Mark Potosnak and Maria Papiez who are currently conducting measurements of sesquiterpenes from natural and landscaped vegetation in the Las Vegas, Nevada area. These measurements are obtained through the use of a novel collection system involving a field-portable gas chromatograph with a flame-ionization detector and an attached hydrocarbon collection trap, and a custom-designed glass small-branch chamber. This investigation involves studying the influence of sesquiterpenes on particulate formation and growth in a variety of environments (e.g., rural, urban, suburban) as well as their gas phase products in ambient air through process analysis of the RACM2 output.

Goliff, W. S.; Stockwell, W. R.; Papiez, M.; Potosnak, M.

2006-12-01

173

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

174

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

PubMed

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?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??0.09). Variations in easterly wind direction WD influence N(SU) and N(PS) values (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. PMID:20668888

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

2011-05-01

175

Assessing the regional surface influence through Backward Lagrangian Dispersion Models for aircraft CO2 vertical profiles observations in NE Spain  

NASA Astrophysics Data System (ADS)

In this study the differences in the measured atmospheric CO2 mixing ratio at three aircraft profiling sites in NE Spain separated by 60 km are analyzed in regard to the variability of the surface fluxes in the regional surface influence area. First, the Regional Potential Surface Influence (RPSI) for fifty-one days in 2006 is calculated to assess the vertical, horizontal and temporal extent of the surface influence for the three sites at the regional scale (104 km2) at different altitudes of the profile (600, 1200, 2500 and 4000 meters above the sea level, m a.s.l.). Second, three flights carried out in 2006 (7 February, 24 August and 29 November) following the Crown Atmospheric Sampling (CAS) design are presented to study the relation between the measured CO2 variability and the Potential Surface Influence (PSI) and RPSI concepts. At 600 and 1200 m a.s.l. the regional signal is confined up to 50 h before the measurements whereas at higher altitudes (2500 and 4000 m a.s.l.) the regional surface influence is only recovered during spring and summer months. The RPSI from sites separated by 60 km overlap by up to 70% of the regional surface influence at 600 and 1200 m a.s.l., while the overlap decreases to 10-40% at higher altitudes (2500 and 4000 m a.s.l.). The scale of the RPSI area is suitable to understand the differences in the measured CO2 concentration in the three vertices of the CAS, as CO2 differences are attributed to local surrounding fluxes (February) or to the variability of regional surface influence as for the August and November flights. For these two flights, the variability in the regional scale influences the variability measured in the local scale. The CAS sampling design for aircraft measurements appears to be a suitable method to cope with the variability of a typical grid for inversion models as measurements are intensified within the PBL and the background concentration is measured every ~102 km.

Font, A.; Morguí, J.-A.; Rodó, X.

2011-02-01

176

Geographical patterns in cyanobacteria distribution: climate influence at regional scale.  

PubMed

Cyanobacteria are a component of public health hazards in freshwater environments because of their potential as toxin producers. Eutrophication has long been considered the main cause of cyanobacteria outbreak and proliferation, whereas many studies emphasized the effect of abiotic parameters (mainly temperature and light) on cell growth rate or toxin production. In view of the growing concerns of global change consequences on public health parameters, this study attempts to enlighten climate influence on cyanobacteria at regional scale in Brittany (NW France). The results show that homogeneous cyanobacteria groups are associated with climatic domains related to temperature, global radiation and pluviometry, whereas microcystins (MCs) occurrences are only correlated to local cyanobacteria species composition. As the regional climatic gradient amplitude is similar to the projected climate evolution on a 30-year timespan, a comparison between the present NW and SE situations was used to extrapolate the evolution of geographical cyanobacteria distribution in Brittany. Cyanobacteria composition should shift toward species associated with more frequent Microcystins occurrences along a NW/SE axis whereas lakes situated along a SW/NE axis should transition to species (mainly Nostocales) associated with lower MCs detection frequencies. PMID:24476711

Pitois, Frédéric; Thoraval, Isabelle; Baurès, Estelle; Thomas, Olivier

2014-02-01

177

Geographical Patterns in Cyanobacteria Distribution: Climate Influence at Regional Scale  

PubMed Central

Cyanobacteria are a component of public health hazards in freshwater environments because of their potential as toxin producers. Eutrophication has long been considered the main cause of cyanobacteria outbreak and proliferation, whereas many studies emphasized the effect of abiotic parameters (mainly temperature and light) on cell growth rate or toxin production. In view of the growing concerns of global change consequences on public health parameters, this study attempts to enlighten climate influence on cyanobacteria at regional scale in Brittany (NW France). The results show that homogeneous cyanobacteria groups are associated with climatic domains related to temperature, global radiation and pluviometry, whereas microcystins (MCs) occurrences are only correlated to local cyanobacteria species composition. As the regional climatic gradient amplitude is similar to the projected climate evolution on a 30-year timespan, a comparison between the present NW and SE situations was used to extrapolate the evolution of geographical cyanobacteria distribution in Brittany. Cyanobacteria composition should shift toward species associated with more frequent Microcystins occurrences along a NW/SE axis whereas lakes situated along a SW/NE axis should transition to species (mainly Nostocales) associated with lower MCs detection frequencies. PMID:24476711

Pitois, Frédéric; Thoraval, Isabelle; Baurès, Estelle; Thomas, Olivier

2014-01-01

178

Nutrient shock and incubation atmosphere influence recovery of culturable Helicobacter pylori from water.  

PubMed

Three different media-Columbia agar, Wilkins-Chalgren agar, and Helicobacter pylori special peptone agar-were prepared in a diluted version and compared to the standard medium formulation in order to study a possible nutrient shock effect observed when recovering H. pylori from water by counting the number of CFU. This same parameter was subsequently used to evaluate the influence of the incubation atmosphere by using a modular atmosphere-controlled system to provide different atmospheres and by employing an established gas generation kit as a control. Both a low nutrient content of the media and a rapidly achieved microaerophilic incubation atmosphere proved to increase the numbers of environment-stressed H. pylori organisms recovered. An atmosphere of 5% CO(2), 5% O(2), and 3% H(2) is recommended, although other atmospheres with a low oxygen concentration are also acceptable. Besides highlighting and assessing the importance of several factors in the culturability of H. pylori, this paper demonstrates the potential ability to develop an optimized technique for recovery of this pathogen from water. PMID:14711679

Azevedo, N F; Pacheco, A P; Keevil, C W; Vieira, M J

2004-01-01

179

Nutrient Shock and Incubation Atmosphere Influence Recovery of Culturable Helicobacter pylori from Water  

PubMed Central

Three different media—Columbia agar, Wilkins-Chalgren agar, and Helicobacter pylori special peptone agar—were prepared in a diluted version and compared to the standard medium formulation in order to study a possible nutrient shock effect observed when recovering H. pylori from water by counting the number of CFU. This same parameter was subsequently used to evaluate the influence of the incubation atmosphere by using a modular atmosphere-controlled system to provide different atmospheres and by employing an established gas generation kit as a control. Both a low nutrient content of the media and a rapidly achieved microaerophilic incubation atmosphere proved to increase the numbers of environment-stressed H. pylori organisms recovered. An atmosphere of 5% CO2, 5% O2, and 3% H2 is recommended, although other atmospheres with a low oxygen concentration are also acceptable. Besides highlighting and assessing the importance of several factors in the culturability of H. pylori, this paper demonstrates the potential ability to develop an optimized technique for recovery of this pathogen from water. PMID:14711679

Azevedo, N. F.; Pacheco, A. P.; Keevil, C. W.; Vieira, M. J.

2004-01-01

180

Distinct atmospheric patterns and associations with acute heat-induced mortality in five regions of England  

NASA Astrophysics Data System (ADS)

The main objective of this paper was to identify possible acute heat-induced summer mortality in five regions of England namely the Yorkshire and the Humber, West Midlands, North East, North West and South East regions and reveal associations with specific air flows. For this purpose, backward air mass trajectories corresponding to daily episodes of increased temperatures were produced and divided to clusters, in order to define atmospheric pathways associated with warm air mass intrusions. A statistically significant at 95 % confidence interval increase in daily total mortality (DTMORT) was observed during the selected episodes at all five regions and thus, heat-induced mortality was indicated. The calculated raise was more intense in the West Midlands, North West and South East regions, whereas the results in the North East and Yorkshire and the Humber regions were less evident. Large fractions of thermal episodes, elevated average temperature values and higher average DTMORT levels were primarily associated with the short-medium range South West (SW) and/or East-South East (E-SE) trajectory clusters, suggesting relations among heat-induced mortality and specific atmospheric circulations. Short-medium length of SW and E-SE airflows, calculated by an application of Haversine formula along the centroid trajectory of each cluster, implies the arrival of slow moving air masses. Atmospheric stagnation could enhance human thermal stress due to low wind speed.

Petrou, Ilias; Dimitriou, Konstantinos; Kassomenos, Pavlos

2015-01-01

181

A comparison of Lagrangian precipitation statistics computed with two regional-scale atmospheric transport models  

SciTech Connect

In an earlier paper the authors pointed out that air mass trajectories computed from winds on an isobaric surface or winds averaged throughout a fixed layer were inappropriate for regional-scale acid deposition studies. This is because isobaric and fixed layer models do not adequately treat vertical motions and wind shears that occur during long range transport associated with precipitation. To improve the vertical resolution of regional-scale transport simulations and to more accurately account for large-scale vertical motions and wind shears during thermodynamically stable atmospheric conditions, they developed the enviroplan dual-mode regional air back-trajector model (EDRAB). In this paper they compute Lagrangian precipitation statistics for an entire year of precipitation events at Whiteface Mountain, New York using EDRAB and the widely used NOAA air resources laboratories atmospheric transport and dispersion model (ARL-ATAD).

Dittenhoefer, A.C.; Ferullo, A.F.

1984-01-01

182

Dynamical model of supperrotation of the upper atmosphere in the polar region  

NASA Astrophysics Data System (ADS)

The new mechanism, explaining generation of supperrotation (SR) of upper atmosphere, is proposed. It is established, that this phenomenon can be caused by high-latitude heat source (HHS), which determines the character of motion in the polar region of the atmosphere. It is revealed, that the joint action of the baric field, caused by HHS, ion friction and Coriolis force leads to generation of internal concurrent processes in the wind field, which can provide stability of stationary structure of motion. The experimental discovery of SR in the upper atmosphere gives an illustration of stationary dynamical structure of motion in F-region of the ionosphere. On the basis of analytical solution of non-linear system of equations of free convection it is shown, that SR in high latitude of the upper atmosphere represents non-linear vortex structure in the form of stationary cyclone, the existence of which is caused by HHS. Cyclone rotation of the atmosphere around the pole naturally forms the exceeding the prevalling western-eastern winds. The direction and velocity of the exceeding winds, determined by theoretical modelling of the processes are in good agreement with the experimental data.

Aburjania, G. D.; Chargazia, Kh. Z.; Khantadze, A. G.; Kharshiladze, O. A.

2003-04-01

183

Development of a Regional Arctic Climate System model: Performance of Polar WRF for regional pan-Arctic atmospheric simulations  

NASA Astrophysics Data System (ADS)

Efforts are currently underway to develop a regional Arctic climate system model (RACM), which will include atmosphere, ocean, sea ice, and land components. The atmospheric component of RACM is a version of Weather Research and Forecasting (WRF) model optimized for use in polar regions, known as Polar WRF. Extensive work has been completed to evaluate the performance of Polar WRF in the Arctic, with an emphasis on evaluating a variety of WRF's physical parameterizations and representation of ice covered surfaces. Using a pan-Arctic model domain, the sensitivity of atmospheric circulation, temperature, moisture, and precipitation is examined as a response to model physics options in boundary layer schemes, microphysics schemes, and longwave and shortwave radiation schemes. In addition, lower boundary land use properties (albedo, emissivity) for ice covered surfaces and fractional sea ice forcing options are examined. For each experiment, a three-member ensemble of January, April, July, and October one month simulations is used and compared with the NCEP/DOE Reanalysis II, with an emphasis on comparison with the broad features of the Arctic climate. Simulations with and without data assimilation will be presented. Significant biases in the circulation over the North Pacific are found for all model configurations that do not use data assimilation.

Higgins, Matthew; Cassano, John

2010-05-01

184

Influence of ocean surface conditions on atmospheric vertical thermodynamic structure and deep convection  

NASA Technical Reports Server (NTRS)

The authors analyze the influence of Sea Surface Temperature (SST) and surface wind divergence on atmospheric thermodynamic structure and the resulting effects on the occurrence of deep convection using National Meteorological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential energy (CAPE), but also an unstable planetary boundary layer (PBL). A stable PBL is observed to suppress deep convection even when CAPE is positive. Variations of SST have a major effect on CAPE, but surface wind divergence can also affect deep convection by changing the lapse rate in the lower troposphere and humidity in the PBL. Specifically, when SST is greater than or equal to 28 C, CAPE is always positive, and surface wind divergence does not qualitatively change the buoyancy profile above the PBL. Strong surface wind divergence, however, stabilizes the PBL so as to suppress the initiation of deep convection. In warm SST regions, CAPE is greater than 0 regardless of assumptions about condensate loading, although the pseudoadiabatic limit is more consistent with the observed deep convection than the reversible moist-adiabatic limit under these circumstances. When SST is less than 27 C, CAPE is usually negative and inhibits convection, but strong surface wind convergence can destabilize the inversion layer and moisten the PBL enough to make the atmosphere neutrally stable in the mean. As a result, deep convection is generally enhanced either when SST is greater than or equal to 28 C in the absence of strong surface wind divergence or when strong surface wind convergence occurs even if SST is less than 27 C. The anomalous suppression of deep convection in the warm area of the equatorial west Pacific lying between the intertropical convergence zone (ITCZ) and south Pacific convergence zone (SPCZ) is probably caused by dryness in the PBL and an inversion in that area. The seasonal cycles of deep convection and surface wind divergence are in phase with the maximum solar radiation and lead SST for one to three months in the central Pacific. The change of PBL relative humidity plays a critical role in the changeover to convective instability in this case. The seasonal change of deep convection and associated clouds seems not to have important effects on the seasonal change of local SST in the central Pacific.

Fu, Rong; Del Genio, Anthony D.; Rossow, William B.

1994-01-01

185

Atmospheric results from a regional Arctic climate model: Comparison of coupled and uncoupled simulations  

NASA Astrophysics Data System (ADS)

A new regional Arctic climate model (RACM) has been developed which includes atmosphere, ocean, sea ice, and land components. The atmospheric model used in RACM is the Weather Research and Forecasting (WRF) model. The ocean and sea ice models are the same as those used in the NCAR Community Climate System Model (CCSM3), although used on a regional domain, and are the Los Alamos National Laboratory POP ocean model and CICE sea model. Land surface processes and hydrology are represented by the Variable Infiltration Capacity (VIC) model. These four climate system component models are coupled using the NCAR CCSM coupler CPL7. The goal of the RACM project is to develop a regional climate model that is capable of performing multi-decadal simulations of the Arctic physical climate system. Initial simulations with the fully coupled RACM will be presented and compared with uncoupled WRF-only simulations for the period 1989 to 2007. Analysis of the coupled and uncoupled simulations will provide insight into the advantages and disadvantages of coupled versus uncoupled regional model downscaling efforts. These simulations will be submitted to the Coordinated Regional Downscaling Experiment (CORDEX) archive as a contribution to the IPCC Fifth Assessment Report. RACM model domain. Shaded region shows extent of WRF and VIC model domains. Inner region with bathymetry shading shows extent of POP and CICE model domain.

Cassano, J. J.; Higgins, M.

2010-12-01

186

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

187

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

188

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

Microsoft Academic Search

This work presents a few preliminary results from a collisional-radiative (CR) model intended to describe an argon microwave (2.45 GHz) plasma at atmospheric pressure. This model aims to investigate the influence of dissociative recombination products on the Saha-Boltzmann plasma equilibrium. The model is tested through comparison with experimental results obtained in an argon plasma column generated by a traveling electromagnetic

Abel Sainz; Joelle Margot; Maria Carmen Garcia; Maria Dolores Calzada

2004-01-01

189

[Concentration distribution of metal elements in atmospheric aerosol under different weather conditions in Qingdao Coastal Region].  

PubMed

To know the influence of different weather conditions on the concentration of metal elements in aerosols in the coastal region, total suspended particles (TSP) samples were collected from April to May 2012, and August 2012 to March 2013 in the Qingdao coastal region, and common trace metals were analyzed by using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The results showed that Al, Ca, Fe, Na, K and Mg were the dominant metal elements in TSP, and the sum of the six elements accounted for 94.2% of the sum of all metals. TSP and metal elements had significant monthly variations, Fe, Al, K, Ca, Mg, Zn, Ba, Mn, Ti, Sr and Li had the highest concentration in November and January, while Be, Sc, Co, Ni and Cr showed the highest value in January. Na had the highest concentration in August, November and February, and the lowest in December. Pb had the highest concentration in January and February, and the lowest in August and December. Enrichment factors indicated that Be, Co, Al, Ca, Fe, K, Mg, Mn, Sr and Ti were mainly affected by natural sources; Li, Cr, Ni, Zn, Ba and Na were affected by natural sources and part of anthropogenic sources; Pb was mainly from anthropogenic sources. Different weather conditions had great impact on TSP and metal elements concentrations, all the measured metals had the highest concentrations in smog except Ti. Compared with the sunny day, the concentration of atmospheric particulate Ti decreased, while the other elements increased by 1 to 4 times in smog. Li, Be, Cr, Ni, Al, Fe, Mg and Mn had little variation in concentration in foggy day, and the concentration of Pb and Na increased considerably. The concentration of Co, Ca and Ti reduced obviously in fog. Except for Cr, Co and Ti, the other elements increased by 1 to 3 times in haze. Most of the elements had the minimal enrichment factors in sunny day, while the other had the maximal enrichment factor in foggy day. Enrichment factors of Ni, Zn, Ba, K, Na, Pb and Sr varied in the order of sunny day < haze day < smog day

Chen, Xiao-Jing; Qi, Jian-Hua; Liu, Ning; Zhang, Xiang-Yu; Shen, Heng-Qing; Liu, Ming-Xu

2014-10-01

190

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

191

Influence of 21st century atmospheric and sea surface temperature forcing on West African climate  

SciTech Connect

he persistence of extended drought events throughout West Africa during the 20th century has motivated a substantial effort to understand the mechanisms driving African climate variability, as well as the possible response to elevated greenhouse gas (GHG) forcing. We use an ensemble of global climate model experiments to examine the relative roles of future direct atmospheric radiative forcing and SST forcing in shaping potential future changes in boreal summer precipitation over West Africa. We find that projected increases in precipitation throughout the Western Sahel result primarily from direct atmospheric radiative forcing. The changes in atmospheric forcing generate a slight northward displacement and weakening of the African easterly jet (AEJ), a strengthening of westward monsoon flow onto West Africa and an intensification of the tropical easterly jet (TEJ). Alternatively, we find that the projected decreases in precipitation over much of the Guinea Coast region are caused by SST changes that are induced by the atmospheric radiative forcing. The changes in SSTs generate a weakening of the monsoon westerlies and the TEJ, as well as a decrease in low-level convergence and resultant rising air throughout the mid levels of the troposphere. Our experiments suggest a potential shift in the regional moisture balance of West Africa should global radiative forcing continue to increase, highlighting the importance of climate system feedbacks in shaping the response of regional-scale climate to global-scale changes in radiative forcing.

Skinner, Chris B [Stanford University; Ashfaq, Moetasim [ORNL; Diffenbaugh, Noah [Stanford University

2011-01-01

192

Cheap Artificial AB-Mountains, Extraction of Water and Energy from Atmosphere and Change of Regional Climate  

E-print Network

Author suggests and researches a new revolutionary method for changing the climates of entire countries or portions thereof, obtaining huge amounts of cheap water and energy from the atmosphere. In this paper is presented the idea of cheap artificial inflatable mountains, which may cardinally change the climate of a large region or country. Additional benefits: The potential of tapping large amounts of fresh water and energy. The mountains are inflatable semi-cylindrical constructions from thin film (gas bags) having heights of up to 3 - 5 km. They are located perpendicular to the main wind direction. Encountering these artificial mountains, humid air (wind) rises to crest altitude, is cooled and produces rain (or rain clouds). Many natural mountains are sources of rivers, and other forms of water and power production - and artificial mountains may provide these services for entire nations in the future. The film of these gasbags is supported at altitude by small additional atmospheric overpressure and may be connected to the ground by thin cables. The author has shown (in previous works about the AB-Dome) that this closed AB-Dome allows full control of the weather inside the Dome (the day is always fine, the rain is only at night, no strong winds) and influence to given region. This is a realistic and cheap method of economical irrigation, getting energy and virtual weather control on Earth at the current time.

Alexander Bolonkin

2008-05-11

193

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

194

Influence of Uncertainty On Regional Landslide Hazard Forecasts  

NASA Astrophysics Data System (ADS)

A hillslope model, coupling a dynamic, physically based and distributed hydrological model with the infinite slope model, has been applied to a catchment of 1.6 square kilometres in SE Spain in order to forecast rainfall triggered shallow landsliding on a regional scale. After incorporation of the variability in the shear strength parameters in the simulation, the area of simulated failure matches 69% of the observed landslide occurrence over the period 1973 - 1998. Despite this reasonable agreement, the model performance is not entirely adequate. The landslide density, the area of the occurred landslides over the total catchment area, is not proportional to the simulated proba- bility of failure, although they are in theory exchangeable. The probability of failure underestimates the landslide density for the gentler slopes (< 14), whereas it overes- timates the landslide density for the steeper, more susceptible slopes. Thus, the model returns a conservative assessment for the more susceptible slopes but fails to return a reliable assessment of the landslide hazard for a part of the region. The recognition of additional sources of uncertainty may reduce the discrepancy between the probabil- ity of failure and the observed landslide density. This would result in a better hazard assessment on which mitigation measures can be based. Several factors have been identified that may be responsible for the discrepancy found, namely pore pressure, soil depth, strain softening and local variations in slope angle. of these factors, the effects on the forecast of landslides have been evaluated. The results demonstrate that local deviations in the slope angle have a relatively large influence on both measures of landslide hazard. This variation in slope angle is presumed to he represented by the Digital Elevation Model, or DEM, on a sub-pixel scale. If this information can be linked or extracted from the DEM, more accurate forecasts of the landslide density may be obtained.

van Beek, L. P. H.; van Asch, Th. W. J.

195

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

PubMed

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

2013-10-22

196

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

197

Human and Natural Influences on the Changing Thermal Structure of the Atmosphere (Invited)  

NASA Astrophysics Data System (ADS)

Since the late 1970s, satellite-based instruments have monitored global changes in atmospheric temperature. These measurements reveal multi-decadal 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 multi-model archive and multiple observational data sets. 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 the first 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.

Santer, B. D.; Painter, J.; Bonfils, C.; Mears, C. A.; Solomon, S.; Wigley, T. M.; Gleckler, P. J.; Schmidt, G. A.; Doutriaux, C.; Gillett, N. P.; Taylor, K. E.; Thorne, P.; Wentz, F. J.

2013-12-01

198

Atmospheric and Laser Spectral Influences on the Column CO2 Measurements at 1.57 ?m  

NASA Astrophysics Data System (ADS)

The 2007 National Research Council Decadal Survey recommended implementation of the Active Sensing of CO2 Emission over Nights, Days, and Seasons (ASCENDS) mission to address uncertainties in the knowledge of the sources and sinks of atmospheric carbon dioxide. Consequently, ASCENDS has become a part of NASA plans to monitor atmospheric carbon dioxide form space using active remote sensing. One such technique under evaluation by NASA Langley Research Center is the integrated path differential absorption (IPDA) lidar operating near 1571 nm. High precision and accuracy, of about 0.1% each, are required for the carbon dioxide mixing ratio measurements in order to improve our understanding of the gas sources and sinks. Therefore, applying the IPDA technique requires an evaluation of the influence of systematic errors and biases resulting from uncertainties in various atmospheric conditions. These conditions include atmospheric temperature, pressure and relative humidity. Furthermore, the impacts of these conditions on the spectral characteristics of the carbon dioxide absorption, transmitted laser source and other interfering atmospheric species, such as absorbing molecules and scattering aerosols have to be investigated. In this paper systematic error sources are evaluated for measurements of atmospheric carbon dioxide using the IPDA technique. The study is focused on the carbon dioxide R24 line at 1571.111903 nm wavelength. This line has been selected for operation by the airborne Multi-functional Fiber Laser Lidar (MFLL) system that is a precursor to a space-based IPDA system. For modeling the systematic effects, 2008 HITRAN database was used, as well as most recent updates, to obtain the spectral lines parameters. The Voigt profile was applied to model the absorption spectra of carbon dioxide, as well as those of the interfering species consisting of water vapor, carbon monoxide, nitrous oxide, oxygen, ozone, acetylene and methane. For all species, absorption lines within the spectral range of 1570.95 nm to 1571.30 nm were included in the calculation. The 1986 AFGL mid-latitude summer atmospheric model parameters were applied covering 0 to 80 km altitude. The calculations were performed at the carbon dioxide line-center (on-line), +3 pm and +10 pm side-lines, and +50 pm and -50 pm off-lines. Influences of pressure (and pressure shift) and temperature sensitivities of the absorption cross-section on column carbon dioxide measurements are presented. Influences of laser line-width, spectral purity and spectral stability for operation at the on-line and side-line positions are also discussed.

Refaat, T. F.; Ismail, S.; Kooi, S. A.; Lin, B.; Harrison, F. W.; Browell, E. V.

2012-12-01

199

Multi-decadal variations of atmospheric aerosols from 1980 to 2009: sources and regional trends  

NASA Astrophysics Data System (ADS)

Aerosol variations and trends over different land and ocean regions during 1980-2009 are analyzed with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and observations from multiple satellite sensors and ground-based networks. Excluding time periods with large volcanic influences, the tendency of aerosol optical depth (AOD) and surface concentration over polluted land regions is consistent with the anthropogenic emission changes. The largest reduction occurs over Europe, and regions in North America and Russia also exhibit reductions. On the other hand, East Asia and South Asia show AOD increases, although relatively large amount of natural aerosols in Asia makes the total changes less directly connected to the pollutant emission trends. Over major dust source regions, model analysis indicates that the dust emissions over the Sahara and Sahel respond mainly to the near-surface wind speed, but over Central Asia they are largely influenced by ground wetness. The decreasing dust trend in the tropical North Atlantic is most closely associated with the decrease of Sahel dust emission and increase of precipitation over the tropical North Atlantic, likely driven by the sea surface temperature increase. Despite significant regional trends, the model-calculated global annual average AOD shows little changes over land and ocean in the past three decades, because opposite trends in different regions cancel each other in the global average. This highlights the need for regional-scale aerosol assessment, as the global average value conceals regional changes, and thus is not sufficient for assessing changes in aerosol loading.

Chin, Mian; Diehl, T.; Tan, Q.; Prospero, J. M.; Kahn, R. A.; Remer, L. A.; Yu, H.; Sayer, A. M.; Bian, H.; Geogdzhayev, I. V.; Holben, B. N.; Howell, S. G.; Huebert, B. J.; Hsu, N. C.; Kim, D.; Kucsera, T. L.; Levy, R. C.; Mishchenko, M. I.; Pan, X.; Quinn, P. K.; Schuster, G. L.; Streets, D. G.; Strode, S. A.; Torres, O.; Zhao, X.-P.

2013-07-01

200

The influence of thermal stratification in the free atmosphere on the power extracted by a very large wind farm  

NASA Astrophysics Data System (ADS)

In the present study, the influence of thermally-stratified free atmosphere on the power extracted by a very large wind farm is investigated. A suit of large-eddy simulations of atmospheric boundary layer (ABL) flow inside and above an infinite wind farm is performed including the effect of earth's rotation and free-atmosphere stability. In the simulations, tuning-free Lagrangian scale-dependent dynamic models are used to model the subgrid-scale turbulent fluxes, while the turbine-induced forces are parameterized taking advantage of an actuator disk model. It is shown that for a given surface cover (with and without turbines) the thermal stratification in the free atmosphere limits the turbulent transport away from the surface compared with the unstratified case, leading to lower entrainment and boundary-layer depth. Due to the fact that in an infinite wind farm, vertical energy transport associated with turbulence is the only source of kinetic energy, lower entrainment leads to lower power production by the wind turbines. In particular, for the wind-turbine arrangement considered in this study, the power output from the wind farm is reduced by 40 percent when the potential temperature lapse rate in the free atmosphere increases from 1 to 10 K/km. Moreover, it is shown that the presence of the turbines has significant effect on the growth of the boundary-layer height. The output of LES is also employed to analyze the turbulent kinetic energy (TKE) budgets in a very large wind farm. It is shown that the shear production, which is the main source of TKE, has a peak at the top of the wind-turbine region where the strong wind shear occurs. This is consistent with the fact that the peak shear stress also occurs at the edge of the wind-turbine wake and has higher value compared with the surface shear stress in the absence of turbines. It is also shown that in a very large wind farm the energy transfer from the resolved-scale TKE to the SGS also has a peak at the top of the wind-turbine region. The LES data is further used to study the other terms in the TKE budget equation such as turbulent transport and diffusion by pressure effects and subgrid modes for different values of potential temperature lapse rate in the free atmosphere.

Abkar, Mahdi; Porté-Agel, Fernando

2013-04-01

201

Modeling the Arctic Atmosphere with the Regional Arctic Climate Model (RACM)  

NASA Astrophysics Data System (ADS)

A coupled atmosphere - ocean - sea ice - land regional Arctic climate model (RACM) has recently been developed. The atmospheric model used in RACM is the Weather Research and Forecasting (WRF) model. The ocean and sea ice models are the same as those used in the NCAR Community Climate System Model (CCSM3), although used on a regional domain, and are the Los Alamos National Laboratory POP ocean model and CICE sea model. Land surface processes and hydrology are represented by the Variable Infiltration Capacity (VIC) model. These four climate system component models are coupled using the NCAR CCSM coupler CPL7. Initial results from this model will be presented that emphasize the model's ability to simulate the full annual cycle of atmosphere and land state. Results from a ten-year (1989-1999) RACM simulation will be presented and compared with uncoupled WRF-only simulations. The comparison will highlight differences between the atmosphere-land and fully coupled simulations. Future plans for RACM will also be presented, including the addition of ice sheet and dynamic vegetation models.

Cassano, J. J.; Higgins, M.; Hughes, M. R.; Gutowski, W. J.; Lettenmaier, D. P.; Maslowski, W.

2011-12-01

202

Regional US carbon sinks from three-dimensional atmospheric CO2 sampling  

PubMed Central

Studies diverge substantially on the actual magnitude of the North American carbon budget. This is due to the lack of appropriate data and also stems from the difficulty to properly model all the details of the flux distribution and transport inside the region of interest. To sidestep these difficulties, we use here a simple budgeting approach to estimate land-atmosphere fluxes across North America by balancing the inflow and outflow of CO2 from the troposphere. We base our study on the unique sampling strategy of atmospheric CO2 vertical profiles over North America from the National Oceanic and Atmospheric Administration/Earth System Research Laboratory aircraft network, from which we infer the three-dimensional CO2 distribution over the continent. We find a moderate sink of 0.5 ± 0.4 PgC y-1 for the period 2004–2006 for the coterminous United States, in good agreement with the forest-inventory-based estimate of the first North American State of the Carbon Cycle Report, and averaged climate conditions. We find that the highest uptake occurs in the Midwest and in the Southeast. This partitioning agrees with independent estimates of crop uptake in the Midwest, which proves to be a significant part of the US atmospheric sink, and of secondary forest regrowth in the Southeast. Provided that vertical profile measurements are continued, our study offers an independent means to link regional carbon uptake to climate drivers. PMID:20937899

Crevoisier, Cyril; Sweeney, Colm; Gloor, Manuel; Sarmiento, Jorge L.; Tans, Pieter P.

2010-01-01

203

Regional-scale evaluation of a land surface scheme from atmospheric boundary layer observations  

NASA Astrophysics Data System (ADS)

The study describes an evaluation of three configurations of the Interactions Soil-Biosphere-Atmosphere (ISBA) land surface scheme fully coupled with the Meso-NH mesoscale atmospheric model. The ability of the modeling system to correctly reproduce the screen-level variables as well as the boundary layer characteristics is examined for more than 30 clear convective days monitored during the CERES 2005 and 2007 field campaigns. For the horizontal resolution considered (8 km), this study shows that the boundary layer characteristics and the low-level variables are better simulated when the subgrid-scale surface process variability is simulated explicitly using the so-called "tiling method." An additional improvement is brought when the CO2 diurnal cycle is used interactively because of the physical link between the stomatal conductance used both for CO2 assimilation and plant transpiration. The parameterization of this link between CO2 and evaporation fluxes improves the simulation of the Bowen ratio and therefore of the atmospheric boundary layer. The last part of the paper discusses the realism of the simulated regional field of CO2 when the carbon configuration is activated in the mesoscale model. Large regional variability of CO2 within the atmospheric boundary layer is found in response to the spatial and seasonal variability of CO2 surface fluxes with respect to the three main land covers in the area: pine forest, extensive winter (wheat), and summer (maize) crops.

Noilhan, J.; Donier, S.; LacarrèRe, P.; Sarrat, C.; Le Moigne, P.

2011-01-01

204

Regional Variation and Trends in IASI-Observed Atmospheric Ammonia Concentrations over the United States  

NASA Astrophysics Data System (ADS)

Quantifying atmospheric ammonia is a critical first step in investigating its role in the formation of fine particulate matter and ecosystem change. This study uses five years (2008-2012) of a new measurement of ammonia column concentrations derived from the Infrared Atmospheric Sounding Interferometer (IASI) instrument to explore ammonia levels in several regions (e.g. the Midwest, California, the Southeast) of the United States. These satellite measurements offer extensive daily coverage, providing a constraint on the evolution and spatial variation of ammonia across the United States. We identify observed ammonia variation between the regions in terms of both intra-annual (seasonal) change and trends throughout the entire time period. These variations are related to factors controlling ammonia emissions, chemistry and deposition, such as human and animal populations, farming practices, land use change and meteorological variables. These variations can also be used to drive Earth system model simulations of ammonia's effects on air quality, radiation balance and environmental degradation.

Schiferl, L. D.; Heald, C. L.; Van Damme, M.; Clerbaux, C.; Coheur, P.

2013-12-01

205

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

206

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

207

Simultaneous mesosphere-lower thermosphere and thermospheric F region observations using middle and upper atmosphere radar  

Microsoft Academic Search

Simultaneous MLT (mesosphere-lower thermosphere) and thermospheric F region (upper thermosphere and ionosphere together) observations conducted using the middle and upper atmosphere (MU) radar (35°N, 136°E) in alternate meteor and incoherent scatter modes in October 2000 and March 2001 are presented. The continuous observations, each lasting more than a week, provide simultaneous zonal and meridional wind velocities at MLT altitudes (80–95

N. Balan; S. Kawamura; T. Nakamura; M. Yamamoto; S. Fukao; W. L. Oliver; M. E. Hagan; A. D. Aylward; H. Alleyne

2006-01-01

208

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

209

On the simulation of allergenic pollen exposition and its atmospheric transport on regional scale  

NASA Astrophysics Data System (ADS)

In Germany approximately 30% of the population is vulnerable to pollinosis (hay fever). Exposure to allergenic pollen affects vulnerable persons recurring seasonally, but depending on the individual susceptibility to individual pollen species. To prevent the suffering the patients usually use preventive drugs and rely on the current pollen forecast. However, recently used pollen forecast models mainly consider temperature sums to predict pollen exposition by different plant species. The models often fail to describe the impact of regionally variable environmental conditions on plant growth which depends on the soil characteristics that affect the water and nutrient availability. Furthermore, water and nutrient availability may significantly affect the pollen yield and its allergenic potential. Thus, the improvement of the simulations of the exposition of allergenic pollen by plants and atmospheric pollen loads on the regional scale could improve the preventive medication of vulnerable persons. We propose a new soil-plant-atmosphere model system that allows a dynamic ressource aquisition for the plant biomass growth to account for the allergenic potential of exposed pollen and the subsequent pollen transport in the atmosphere. Therefore, to simulate pollen exposure the land surface model Expert-N (soil-plant-system model) was coupled to the Weather Research and Forecast model (WRF). Expert-N uses site specific physical soil properties to simulate the nutrient and water transport, and the carbon and nitrogen turnover, as well as the interactions between plant and soil. The allergenic potential of pollen yield is simulated using a new C- and N-allocation model which accounts for the production of carbon-based secondary compounds (CBSCs). These CBSCs are involved in the determination of the allergenic potential of pollen. The WRF model is used to predict the weather conditions for plant growth. Depending on the weather conditions pollen exposed by the plants is then released into the atmosphere and transported using the WRF-Chem model, an upgrade of the WRF model, to simulate matter transport in the atmosphere.

Biernath, Christian; Klein, Christian; Hoffmann, Peter; Gayler, Sebastian; Priesack, Eckart

2013-04-01

210

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

211

Improving Regional Forecast by Assimilating Atmospheric InfraRed Sounder (AIRS) Profiles into WRF Model  

NASA Technical Reports Server (NTRS)

In data sparse regions, remotely-sensed observations can be used to improve analyses and produce improved forecasts. One such source comes from the Atmospheric InfraRed Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), represents one of the most advanced space-based atmospheric sounding systems. The purpose of this paper is to describe a procedure to optimally assimilate high resolution AIRS profile data into a regional configuration of the Advanced Research WRF (ARW) version 2.2 using WRF-Var. The paper focuses on development of background error covariances for the regional domain and background type, and an optimal methodology for ingesting AIRS temperature and moisture profiles as separate overland and overwater retrievals with different error characteristics. The AIRS thermodynamic profiles are derived from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm and contain information about the quality of each temperature layer. The quality indicators were used to select the highest quality temperature and moisture data for each profile location and pressure level. The analyses were then used to conduct a month-long series of regional forecasts over the continental U.S. The long-term impacts of AIRS profiles on forecast were assessed against verifying NAM analyses and stage IV precipitation data.

Chou, Shih-Hung; Zavodsky, Brad; Jedlovec, Gary J.

2009-01-01

212

Earth’s Interaction Region: Plasma-Neutral Interactions in the Weakly Ionized gas of Earth’s High Latitude Upper Atmosphere  

NASA Astrophysics Data System (ADS)

The high-latitude regions of Earth’s upper atmosphere are strongly influenced by plasma-neutral interactions. These interactions couple electrodynamic processes of the ionosphere with hydrodynamic processes of the more abundant thermosphere neutral gas, consequently connecting the high-latitude upper atmosphere to distant regions of the geoplasma environment. This produces a complex spatial and temporal interplay of competing processes that results in a myriad of physical and chemical responses and a rich array of neutral and plasma morphologies that constitute the high-latitude thermosphere and ionosphere. The altitude extent from the lower thermosphere to the upper ionosphere (90km – 1000km) can be considered Earth’s space-atmosphere interaction region - likened to the solar chromosphere’s interaction region where radiative processes and hydrodynamic waves from the dense lower atmosphere produce a cold lower boundary that quickly transitions over a few 100 kilometers to neutral and plasma temperatures that are five times hotter. A thousand or more kilometers further in altitude, Earth's upper atmosphere becomes a hot, collisionless, geomagnetically controlled protonosphere whose neutral and plasma population originates from the thermosphere and ionosphere. A grand challenge in the study of Earth’s interaction region is how the collision-dominated thermosphere/ionosphere system exchanges energy, mass and momentum with the collisionless magnetosphere. This talk will focus primarily on collision-dominated processes of the high-latitude ionosphere and the electromagnetic energy transfer processes that lead to frictional heating of ions and neutrals, and plasma instability phenomenon that leads to extreme electron heating. Observations of the ionosphere response to these processes will be illustrated using incoherent scatter radar measurements. Relevance to the solar chromosphere will be identified where appropriate and outstanding issues in Earth’s interaction region will be discussed.

Thayer, Jeffrey; Hsu, Vicki

2015-04-01

213

Influence of Sea-ice on Inter-Annual Climate Variability in Coupled Ocean-Sea-ice-Atmosphere Simulations  

Microsoft Academic Search

There is currently considerable interest in the role of sea-ice on changes in climate and climate variability. Variations in sea-ice modify the atmosphere and oceans through its influence on albedo, ocean-atmosphere heat exchange and ocean buoyancy. Studies show clearly that interactions between sea-ice, oceans and atmosphere are likely to be important at seasonal to decadal timescales of variability. The interaction

J. S. Singarayer; P. J. Valdes; J. L. Bamber

2004-01-01

214

Influence of large-scale atmospheric circulation on European sea level: results based on the wavelet transform method  

Microsoft Academic Search

We examine relationships between the variability in the long-term time series of European sea level and the large-scale atmospheric circulation represented by the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) indices using the wavelet transform (WT). Results demonstrate that between 10% and 35% of the variance in winter mean sea level may be explained by the atmospheric circulation influence.

S. J EVREJEV; J. C. MOORE; P. L. W O O DW; O RT; A. G RINSTED

2005-01-01

215

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

216

On the influence of the sea surface temperature on the carbon dioxide exchange with the atmosphere  

NASA Astrophysics Data System (ADS)

The influence of the sea surface temperature (SST) on the carbon dioxide (CO2) exchange with the atmosphere at different spatial and temporal scales, which has a multidirectional character, was studied. The initial data included the monthly averages of the CO2 flux during the period of 1982-2011 at grid nodes of 4° by latitude and 5° by longitude, as well as the SST satellite data from January 1, 1982 to December 31, 2012 at the geographical grid nodes of 0.25° × 0.25°. Statistical models of estimation of the resulting global CO2 flux were suggested on the basis of data on SST anomalies. It is demonstrated that the SST variations in the equatorial zone mostly control the interannual fluctuations of the resulting CO2 flux in the ocean-atmosphere system.

Karlin, L. N.; Malinin, V. N.; Gordeeva, S. M.

2015-02-01

217

Influence of non-Kolmogorov atmospheric turbulence on the spectral changes of rectangular array beams  

NASA Astrophysics Data System (ADS)

Based on the non-Kolmogorov spectrum, using the extended Huygens-Fresnel principle, the analytical expressions for the spectrum of the coherent and incoherent superpositions of rectangular array Gaussian Schell-model (RAGSM) beams propagating through non-Kolmogorov atmospheric turbulence are derived, and are used to study the influence of non-Kolmogorov atmospheric turbulence on spectral changes of coherent and incoherent superpositions RAGSM beams. It is shown that, with the increment of the general exponent ? and the inner scale of turbulence l0, as well as the decrement of the general structure constant C˜n2, the magnitude of the spectral shift will increase, the magnitude of spectral transition will decrease and the critical position of spectral transition will decrease. The outer scale of turbulence L0 has little effect on the spectral shift and spectral transition.

Li, Jinhong; Peng, Yanyan; Duan, Meiling; Wei, Jilin

2015-03-01

218

Impact of the Lower Atmosphere on Variability in the Lower Thermosphere and Turbopause Region (Invited)  

NASA Astrophysics Data System (ADS)

Recent development of whole atmosphere models has enabled a window into the degree to which the lower atmosphere induces variability in the thermosphere and ionosphere system. Processes associated with tropospheric weather systems, wind flow over topography, and convective adjustment in the lower atmosphere generates a spectrum of waves that propagate upward. The amplification of these model-resolved waves drives strong winds and shear near the turbopause and lower thermosphere region. The modeled vertical structure and shear is similar to wind observations in the lower thermosphere enabling their impact to be assessed. The rich spectrum of short-period (1 to 3 hours) waves manifest in the thermosphere also has a clear ionospheric signature, which is apparent in incoherent scatter observations and lidar measurements. The lower thermosphere is also the region where a whole spectrum of migrating and non-migrating tides reaches a peak as they propagate from their sources in the lower atmosphere. The spectrum of tides drives circulation patterns on a range of scales from global to regional, which act as a mixing agent. The model can be used to quantify the role of mixing by tides, and the impact on the ratio of light atomic (oxygen) to heavier molecular (nitrogen) species, which has a direct impact on ionospheric recombination rates. The seasonal/latitudinal variation of tides can induce variations in mixing and O/N2 ratio. Conventional wisdom suggests that most the thermospheric mixing is from small-scale eddies near the turbopause from breaking of smaller-scale (10 to 100 km) gravity waves, which would be unresolved in typical general circulation models so have to be parameterized. The new whole atmosphere models can be used to determine the contribution to mixing by the spectrum of atmospheric tides and larger-scale model-resolved waves. At high latitudes, Joule heating rates and auroral precipitation from magnetospheric sources are also at their peak in the lower thermosphere, and strong divergent neutral winds from ion drag can develop considerable structure at these altitudes.

Fuller-Rowell, T. J.; Akmaev, R. A.; Wu, F.; Fedrizzi, M.; Codrescu, M.; Olsen, J.

2013-12-01

219

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

220

Steep declines in atmospheric base cations in regions of Europe and North America  

NASA Astrophysics Data System (ADS)

HUMAN activities have caused marked changes in atmospheric chemistry over large regions of Europe and North America. Although considerable attention has been paid to the effects of changes in the deposition of acid anions (such as sulphate and nitrate) on terrestrial and aquatic ecosystems1-7, little is known about whether the concentrations of basic components of the atmosphere have changed over time8,9 and what the biogeochemical consequences of such potential changes might be. In particular, there has been some controversy8-12 as to whether declines in base-cation deposition have countered effects of recent reductions in SO2emission. Here we report evidence for steep declines in the atmospheric concentrations of base cations (sum of non-sea-salt Ca2+, Mg2+, K+ and Na+) over the past 10 to 26 years from high-quality precipitation chemistry records in Europe and North America. To varying but generally significant degrees, these base-cation trends have offset recent reductions in sulphate deposition in the regions examined. The observed trends seem to be ecologically important on decadal timescales, and support earlier contentions8-10 that declines in the deposition of base cations may have contributed to increased sensitivity of poorly buffered ecosystems.

Hedin, Lars O.; Granat, Lennart; Likens, Gene E.; Adri Buishand, T.; Galloway, James N.; Butler, Thomas J.; Rodhe, Henning

1994-01-01

221

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

222

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

223

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

NASA Astrophysics Data System (ADS)

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

Gratz, Lynne E.

224

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

225

Atmospheric CO2 Inversions of the Mid-Continental Intensive (MCI) Region (Invited)  

NASA Astrophysics Data System (ADS)

We combine the SiB3 biosphere model with the RAMS mesoscale meteorology model and associated Lagrangian particle dispersion model (LPDM) and use CO2 observations from an extensive tower network in 2007 to correct a priori ecosystem respiration (ER) and gross primary productivity (GPP) fluxes for a domain consisting of most of North America. In particular, eight of these towers are located in a concentrated ring around the Mid-Continent Intensive (MCI) region of the United States providing one of the densest tower networks (CO2) in the world, in the midst of one of the strongest areas of seasonal carbon flux in the world. The unique area combined with dense observations and relatively simple atmospheric transport provides an incredible test-bed to investigate atmospheric CO2 inversions. Multiple inversion approaches are compared and contrasted. The results are then investigated for sensitivity to a priori inversion designs, boundary inflow contributions, and network density.

Schuh, A. E.; Denning, A.; Ogle, S. M.; Corbin, K.; Uliasz, M.; Davis, K. J.; Lauvaux, T.; Miles, N.; Andrews, A. E.; Petron, G.; Huntzinger, D. N.

2009-12-01

226

Regional synthesis of Mediterranean atmospheric circulation during the Last Glacial Maximum.  

PubMed

Atmospheric circulation leaves few direct traces in the geological record, making reconstructions of this crucial element of the climate system inherently difficult. We produced a regional Mediterranean synthesis of paleo-proxy data from the sea surface to alpine altitudes. This provides a detailed observational context for change in the three-dimensional structure of atmospheric circulation between the Last Glacial Maximum (LGM, approximately 23,000 to 19,000 years ago) and the present. The synthesis reveals evidence for frequent cold polar air incursions, topographically channeled into the northwestern Mediterranean. Anomalously steep vertical temperature gradients in the central Mediterranean imply local convective precipitation. We find the LGM patterns to be analogous, though amplified, to previously reconstructed phases of enhanced meridional winter circulation during the Maunder Minimum (the Little Ice Age). PMID:18669823

Kuhlemann, J; Rohling, E J; Krumrei, I; Kubik, P; Ivy-Ochs, S; Kucera, M

2008-09-01

227

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

228

The Puzzling Chemical Composition of GJ 436b's Atmosphere: Influence of Tidal Heating on the Chemistry  

NASA Astrophysics Data System (ADS)

The dissipation of the tidal energy deposited on eccentric planets may induce a heating of the planet that affects its atmospheric thermal structure. Here we study the influence of tidal heating on the atmospheric composition of the eccentric (e = 0.16) "hot Neptune" GJ 436b, for which inconclusive chemical abundances are retrieved from multiwavelength photometric observations carried out during primary transit and secondary eclipse. We build up a one-dimensional model of GJ 436b's atmosphere in the vertical direction and compute the pressure-temperature and molecular abundances profiles for various plausible internal temperatures of the planet (up to 560 K) and metallicities (from solar to 100 times solar), using a radiative-convective model and a chemical model which includes thermochemical kinetics, vertical mixing, and photochemistry. We find that the CO/CH4 abundance ratio increases with metallicity and tidal heating, and ranges from 1/20 to 1000 within the ranges of metallicity and internal temperature explored. Water vapor locks most of the oxygen and reaches a very high abundance, whatever the metallicity and internal temperature of the planet. The CO2/H2O abundance ratio increases dramatically with metallicity, and takes values between 10-5-10-4 with solar elemental abundances and ~0.1 for a metallicity 100 times solar. None of the atmospheric models based on solid physical and chemical grounds provide a fully satisfactory agreement with available observational data, although the comparison of calculated spectra and observations seems to point to models with a high metallicity and efficient tidal heating, in which high CO/CH4 abundance ratios and warm temperatures in the dayside atmosphere are favored.

Agúndez, Marcelino; Venot, Olivia; Selsis, Franck; Iro, Nicolas

2014-02-01

229

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

230

Water balance estimation for large scale basins from regional atmospheric moisture budgets and comparison to GRACE  

NASA Astrophysics Data System (ADS)

Besides energy fluxes and temperature properties, atmospheric downscaling models also describe the vertical water fluxes and exchange processes between soil and atmosphere. The analysis of long term impacts of land use and climate variations with hydrometeorological models requires a proper description of the energy and water interplay. In our study, we investigate how well the mesoscale Weather Research and Forecasting modeling system WRF (WRF-ARW) is able to reproduce the 2003-2006 water balance of continental scale river catchments and basins without discharge, based on the analysis of atmospheric moisture budgets. The divergence of the vertically integrated moisture flux is used as a proxy for precipitation minus evapotranspiration (P-E). Therefore, at basins where discharge measurements are available or outflow equals zero, the water budget can be determined also for the basin storage change. Global boundary conditions from ECMWF ERA-INTERIM and the NCAR/NCEP Reanalysis are used for the driving of WRF. Water budgets are analyzed for the river basins of Amazon, Yenisei, and Lena, and also for the Sahara and the central arid region of Australia. The results show that for cold and winterly conditions, WRF reproduces the basin water budget quite well. For warm and moist conditions, net water input (P-E) is mostly overestimated. Different model driving with ECMWF and NCEP boundary conditions has small effects for the Siberian tundra. The Amazonian, Saharan and Australian domains show stronger deviances. The evaluation of the derived storage changes with their global counterparts and with the Gravity Recovery And Climate Experiment GRACE suggests that for moist and warm environments, the regional atmospheric model has substantial problems in describing the vertical water fluxes, whereas for cold conditions downscaling is likely to decrease overall uncertainty.

Fersch, Benjamin; Kunstmann, Harald

2010-05-01

231

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

232

Biogenic sulfur compounds in seawater and the atmosphere of the Antarctic region  

NASA Astrophysics Data System (ADS)

Shipboard measurements of dimethyl sulfide (DMS), carbonyl sulfide (COS) and carbon disulfide (CS2) in seawater and the marine boundary layer were performed during a cruise between Punta Arenas (Chile) and Cape Town (South Africa) through the Weddell Sea in November/December 1990. The DMS concentrations in seawater averaged to 71 ngS/l, atmospheric DMS mixing ratios showed a range between 2 and 1048 pptv. In the Weddell Sea where DMS mixing ratios as low as 24 pptv on the average were observed, the extensive ice cover seemed to minimize the gas exchange between seawater and the overlying atmosphere. The COS levels in seawater showed a mean of 3.5 ngS/l with minor variability. Atmospheric COS mixing ratios measured over the Weddell Sea averaged to 453±43 pptv. In contrast, COS concentrations during advection processes of continental air masses over the Drake Passage were evidently higher with a mean of 628±42 pptv. The concentrations of CS2 in the remote marine boundary layer were below the detection limit of 7 pptv, with enhanced concentrations of about 35 pptv observed in air masses influenced by continental inputs. CS2 values in surface seawater were mostly below the detection limit of 0.43 ngS/l with few exceptions revealing CS2 values between 0.48 and 1.43 ngS/l. In 91% of all seawater samples taken during this cruise CS2 were not found in detectable concentrations.

Staubes, R.; Georgii, H.-W.

1993-04-01

233

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

NASA Astrophysics Data System (ADS)

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.; Leister, C.

2014-05-01

234

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

235

Simultaneous mesosphere-lower thermosphere and thermospheric F region observations using middle and upper atmosphere radar  

NASA Astrophysics Data System (ADS)

Simultaneous MLT (mesosphere-lower thermosphere) and thermospheric F region (upper thermosphere and ionosphere together) observations conducted using the middle and upper atmosphere (MU) radar (35°N, 136°E) in alternate meteor and incoherent scatter modes in October 2000 and March 2001 are presented. The continuous observations, each lasting more than a week, provide simultaneous zonal and meridional wind velocities at MLT altitudes (80-95 km), meridional wind velocity in the upper thermosphere (220-450 km), and electron density and peak height in the ionosphere with a time resolution of 1.5 hours. The data seem to suggest that the upper atmospheric regions could be dynamically coupled through mean winds, tides, and waves. Diurnal (24-hour) and semidiurnal (12-hour) tides and waves of periods 16-20 hours and 35-55 hours coexist at MLT and upper thermosphere altitudes, and the waves become stronger than tides at mesopause (?88 km) in both October and March. The data in these equinoctial months also show large differences in mean winds, tides, and waves in the MLT region. The amplitudes and phases of the 24-hour and 12-hour tides at MLT altitudes are compared with those predicted by the global scale wave model (GSWM). The model qualitatively predicts the observed growth of the tides with altitude but does not predict the 12-hour tide becoming stronger than the 24-hour tide at altitudes above mesopause in October.

Balan, N.; Kawamura, S.; Nakamura, T.; Yamamoto, M.; Fukao, S.; Oliver, W. L.; Hagan, M. E.; Aylward, A. D.; Alleyne, H.

2006-10-01

236

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

237

Simulation of iron/dust in the atmosphere by a regional model  

NASA Astrophysics Data System (ADS)

During sporadic desert dust storms mineral aerosol is raised from the ground, diffused to higher elevations and transported away from sources. Through sedimentation, dry deposition and wet scavenging, dust deposited to the ocean brings at the same time iron and phosphorus embedded in dust particles. Iron exposed to the atmospheric (photo-) chemical processing converts from almost non-soluble to relative high soluble state. Only as soluble, iron can be consumed as a nutrient by microorganisms in a primary marine bio-production phase. In ocean regions distant from coastlines where upwelling and river inputs are missing, iron (and phosphorus) is the major potential marine nutrient. Current knowledge on the atmospheric iron cycle is rather unsatisfactory. First, distribution of iron minerals in desert soils is not yet well known. Second, there are uncertainties on how the iron minerals are chemically processed in the atmosphere since there is no agreement on the roles of solar radiation, clouds and pollution and their relative importance. Finally, current iron models are of global domain and cannot sufficiently resolve the dust (and associated iron) life cycle which is highly variable in time and space. Therefore, more accurate information on deposition of iron to the ocean and its soluble state are generally missing today. This paper presents developments of an atmospheric iron model performed by adding the iron component to the regional dust model DREAM. To specify the iron sources in deserts, relatively high resolution data on soil types (4 km) and land cover (1 km) are used in combination with recent field mineralogy studies. Iron minerals are assumed to be embedded in dust and therefore driven by dust; a corresponding governing set of equations specific for the dynamics of embedded iron, as well as pseudo-first order chemical reaction converting from non-soluble to soluble is then developed. Finally, experiments were performed using the model horizontal resolution of about 40 km to simulate an extensive marine bacterial bloom associated with a major dust deposition in the Canary Islands region. Results show that the model is able to reproduce the observed increase of iron solubility along the downwind distance. The model shows that the iron solubility behaves in the same way with respect to the vertical distribution as well - i.e. increases with height. Such findings are consistent with recent studies that showing that the link between atmospheric iron processing and solubility is primarily physical rather than chemical in nature.

Nickovic, S.; Perez, C.

2008-12-01

238

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

239

The Influence of Anthropogenic Aerosol on Multi-Decadal Variations of Historical Global and Regional Climate  

NASA Astrophysics Data System (ADS)

Aerosol presents a large source of uncertainty in climate simulations. The representation of aerosol, and their interaction with clouds, in climate models is changing rapidly. It is important to gauge model performance in simulating these processes, and which aspects of aerosol-climate interaction contribute to uncertainty, to enable effort to be prioritized. Future changes in aerosol entwine air-quality and climate change mitigation options. With rapid reductions in aerosol emissions anticipated in the near-term, it is important to constrain uncertainty to facilitate sound decisions on future policy. We show that climate models that include a representation of the indirect effect of aerosol better reproduce inter-decadal variability in historical global-mean near-surface temperatures, particularly the cooling in the 1950s and 1960s, compared to models with representation of the aerosol direct effect only. Using an adaptive decomposition technique to identify nonlinear trends, analysis of single forcing runs from CMIP5 simulations shows that the mid-twentieth century temperature hiatus is likely to have been influenced strongly by anthropogenic aerosol forcing. In addition to global impacts, aerosol can have a pronounced influence on local climate. Using case studies from regions with large responses to aerosol forcing, we investigate inter-model differences in aerosol burden, and in the sensitivity of atmospheric metrics to aerosol changes. We find a large range of sensitivities to aerosol perturbations, as well as considerable differences in the mass loading of some species on regional scales. This inter-model diversity in aerosol burden and representation of aerosol-cloud interaction can produce substantial variation in simulations of climate variability on multi-decadal timescales.

Wilcox, L.; Highwood, E.

2013-12-01

240

Assessing the regional surface influence through Backward Lagrangian Dispersion Models for aircraft CO2 vertical profiles observations in NE Spain  

NASA Astrophysics Data System (ADS)

A weekly climatology for 2006 composed of 96-h-backward Lagrangian Particle Dispersion simulations is presented for nine aircraft sites measuring vertical profiles of atmospheric CO2 mixing ratios along the 42° N parallel in NE Spain to assess the surface influence at a regional scale (102-103 km) at different altitudes in the vertical profile (600, 1200, 2500 and 4000 meters above the sea level, m a.s.l.). The Potential Surface Influence (PSI) area for the 96-h-backward simulations, defined as the air layer above ground with a thickness of 300 m, are reduced from the continental scale (~107 km2) to the watershed one (~104 km2), when a Residence Time Threshold Criteria (Rttc) greater than 500 s is imposed for each grid cell. In addition, this regional restricted information is confined during 50 h before the arrival for simulations centered at 600 and 1200 m a.s.l. At higher altitudes (2500 and 4000 m a.s.l.), the regional surface influence is only recovered during spring and summer months. For simulations centered at 600 and 1200 m a.s.l. sites separated by ~60 km may overlap 20-50% of the regional surface influences whereas sites separated by ~350 km as such do not overlap. The overlap for sites separated by ~60 km decreases to 8-40% at higher altitudes (2500 and 4000 m a.s.l.). A dense network of sampling sites below 2200 m a.s.l. (whether aircraft sites or tall tower ones) guarantees an appropriate regional coverage to properly assess the dynamics of the regional carbon cycle at a watershed scale (102-103 km length scale).

Font, A.; Morguí, J.-A.; Rodó, X.

2010-03-01

241

RSL: A parallel Runtime System Library for regional atmospheric models with nesting  

SciTech Connect

RSL is a parallel runtime system library developed at Argonne National Laboratory that is tailored to regular-grid atmospheric models with mesh refinement in the form of two-way interacting nested grids. RSL provides high-level stencil and interdomain communication, irregular domain decomposition, automatic local/global index translation, distributed I/O, and dynamic load balancing. RSL was used with Fortran90 to parallelize a well-known and widely used regional weather model, the Penn State/NCAR Mesoscale model.

Michalakes, J.G.

1997-08-01

242

Influence of ethylene glycol pretreatment on effectiveness of atmospheric pressure plasma treatment of polyethylene fibers  

NASA Astrophysics Data System (ADS)

For atmospheric pressure plasma treatments, the results of plasma treatments may be influenced by liquids adsorbed into the substrate. This paper studies the influence of ethylene glycol (EG) pretreatment on the effectiveness of atmospheric plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers with 0.31% and 0.42% weight gain after soaked in EG/water solution with concentration of 0.15 and 0.3 mol/l for 24 h, respectively. Scanning electron microscopy (SEM) shows that the surface of fibers pretreated with EG/water solution does not have observable difference from that of the control group. The X-ray photoelectron spectroscopy (XPS) results show that the oxygen concentration on the surface of EG-pretreated fibers is increased less than the plasma directly treated fibers. The interfacial shear strength (IFSS) of plasma directly treated fibers to epoxy is increased almost 3 times compared with the control group while that of EG-pretreated fibers to epoxy does not change except for the fibers pretreated with lower EG concentration and longer plasma treatment time. EG pretreatment reduces the water contact angle of UHMWPE fibers. In conclusion, EG pretreatment can hamper the effect of plasma treatment of UHMWPE fibers and therefore longer plasma treatment duration is required for fibers pretreated with EG.

Wen, Ying; Li, Ranxing; Cai, Fang; Fu, Kun; Peng, Shujing; Jiang, Qiuran; Yao, Lan; Qiu, Yiping

2010-03-01

243

Numerical study of local\\/regional atmospheric changes caused by a large solar central receiver power plant  

Microsoft Academic Search

A two-dimensional numerical atmospheric mesoscale model with a vertical cross section is applied to study the potential local\\/regional atmospheric effects of the installation of a 100 MWe solar thermal central receiver power plant in California. The plant comprises heliostats (mirrors) covering a portion of ground surface and reflecting sunlight onto a central receiving tower. The model is able to simulate

C. M. Bhumralkar; A. J. Slemmons; K. C. Nitz

1981-01-01

244

Assessing the influence of secondary organic aerosols on long-range atmospheric PAH transport  

NASA Astrophysics Data System (ADS)

We incorporate recent experimental findings on the synergy between secondary organic aerosols (SOA) and polycyclic aromatic hydrocarbons (PAHs) in a global atmospheric chemical transport model to test the influence of different gas-particle partitioning parameterizations on long-range atmospheric transport of PAHs. PAHs, byproducts of organic combustion, are toxic compounds that have been measured in areas distant from sources, such as the Arctic. Historically, the transport of PAHs in the atmosphere has been modeled by assuming that PAHs instantaneously and reversibly equilibrate between the gas phase and a particulate phase, with observed particulate fractions often times exceeding model results for unknown reasons. Recently obtained laboratory-based findings suggest PAHs become trapped in SOA particles during SOA formation and are thus prevented from evaporation and/or oxidation, possibly explaining discrepancies between observed and modeled particulate fractions. Here, we use the global atmospheric chemical transport model GEOS-Chem to investigate whether incorporation of pyrene, a four-ring PAH, into SOA upon formation better represents atmospheric long-range transport and gas-particle speciation of PAHs compared to our default partitioning scheme, in which PAHs instantaneously equilibrate between the gas phase, primary organic carbon aerosols (OC), and black carbon aerosols (BC). In general, we find that BC plays an important role in pyrene transport and gas-particle partitioning, with a model that includes BC producing the best match to observed seasonal variation and magnitude of pyrene particulate fraction. Incorporation of 100% of pyrene into SOA upon emission with fractional evaporation thereafter results in a reasonable match to observed total pyrene concentrations in the northern hemisphere mid-latitudes, but severely overestimates particulate fraction. Assuming that pyrene partitions to SOA following an octanol-air equilibrium partition coefficient upon emission with fractional evaporation thereafter similarly results in reasonable concentration results, but, in contrast, severely underestimates particulate fractions. Instantaneous equilibrium between the gas phase, OC, and BC is the only partitioning parameterization tested that simultaneously provides a good match to observed concentrations and particulate fractions. Other potential influences on pyrene long-range transport tested include spatiotemporal variability in gas-phase oxidant (hydroxyl radical) concentrations, spatiotemporal variability in SOA versus OC and BC, deposition efficiency of SOA versus OC and BC, and incorporation of particle-phase oxidation, with none of these parameterizations impacting PAH gas-particle partitioning as strongly as including BC in the model.

Friedman, C. L.; Selin, N. E.

2013-12-01

245

Structure of the disturbed region of the atmosphere after the nuclear explosion in Hiroshima  

NASA Astrophysics Data System (ADS)

An attempt is undertaken to describe the development of the disturbed region of the atmosphere caused by the nuclear explosion over Hiroshima on August 6, 1945. Numerical simulation of the phenomenon is performed using the dynamic equations for a nonconducting inviscid gas taking into account the combustion of urban buildings, phase changes of water, electrification of ice particles, and removal of soot particles. The results of the numerical calculation of the development of the disturbed region indicate heavy rainfall, the formation of a storm cloud with lightning discharges, removal of soot particles, and the formation of vertical vortices. The temporal sequence of these meteorological phenomena is consistent with the data of observations. Because of the assumptions and approximations used in solving the problem, the results are of qualitative nature. Refinement of the results can be obtained by a more detailed study of the approximate initial and boundary conditions of the problem.

Shcherbin, M. D.; Pavlyukov, K. V.; Salo, A. A.; Pertsev, S. F.; Rikunov, A. V.

2013-09-01

246

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

247

Elevated atmospheric carbon dioxide and leaf litter chemistry: Influences on microbial respiration and net nitrogen mineralization  

SciTech Connect

Elevated atmospheric CO{sub 2} has the potential to influence rates of C and N cycling in terrestrial ecosystems by altering plant litter chemistry and slowing rates of organic matter decomposition. We tested the hypothesis that the chemistry of leaf litter produced at elevated CO{sub 2} would slow C and N transformations in soil. Soils were amended with Populus leaf produced under two levels of atmospheric CO{sub 2} (ambient and twice-ambient) and soil N availability (low and high). Kinetic parameters for microbial respiration and net N mineralization were determined on soil with and without litter during a 32-wk lab incubation. Product accumulation curves for CO{sub 2}-C and inorganic N were fit to a first order rate equation [y=A(1-e{sup -kt})] using nonlinear regression analyses. Although CO{sub 2} treatment affected soluble sugar concentration in leaf litter (ambient =120 g kg{sup -1}, elevated =130 g kg{sup -1}), it did not affect starch concentration or C/N ratio. Microbial respiration, microbial biomass, and leaf litter C/N ratio were affected by soil N availability but not by atmospheric CO{sub 2}. Net N mineralization was a linear function of time and was not significantly different for leaves grown at ambient (50 mg N kg{sup -1}) and elevated CO{sub 2} (35 mg N kg{sup -1}). Consequently, we found no evidence for the hypothesis that leaf litter produced at elevated atmospheric CO{sub 2} will dampen the rates of C and N cycling in soil. 35 refs., 1 fig., 4 tabs.

Randlett, D.L.; Zak, D.R. [Univ. of Michigan, Ann Arbor, MI (United States); Pregitzer, K.S. [Michigan Technical Univ., Houghton, MI (United States); Curtis, P.S. [Ohio State Univ., Columbus, OH (United States)

1996-09-01

248

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

249

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

NASA Astrophysics Data System (ADS)

Many 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

250

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

251

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

252

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

253

REGIONAL APPLICATION OF A BIOGEOCHEMICAL MODEL (PNET-BGC) TO THE ADIRONDACK REGION OF NEW YORK: RESPONES TO CURRENT AND FUTURE CHANGES IN ATMOSPHERIC DEPOSITION  

EPA Science Inventory

Understanding the response of soil and surface waters to changes in atmospheric deposition is critical for guiding future legislation on air pollutants. In this study, the regional response of soil and surface waters in 37 lake watersheds in the Adirondack region of New York to c...

254

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

NASA Astrophysics Data System (ADS)

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.; Xu, K.; Sun, B.; Ding, Z. F.

2012-08-01

255

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

256

Flux measurements of atmospheric CO2 by Lidar: from the micro to the regional scale  

NASA Astrophysics Data System (ADS)

A mechanistic understanding of the global carbon cycle requires quantification of terrestrial ecosystem CO2 fluxes at regional scales. In this paper, we analyze the potential of a Doppler DIAL system to make flux measurements of atmospheric CO2 using the eddy-covariance and boundary layer budget methods and present results from a ground based experiment. In June 2007, a field experiment combining a 2-µm Doppler Heterodyne Differential Absorption Lidar (HDIAL) and in-situ sensors of a 447-m tall tower (WLEF) took place in Wisconsin. The HDIAL measures simultaneously: 1) CO2 mixing ratio, 2) atmosphere structure via aerosol backscatter and 3) radial velocity. We demonstrate how to synthesize these data into regional flux estimates. Lidar-inferred fluxes are compared with eddy-covariance fluxes obtained in-situ at 396m AGL from the tower. In cases where the lidar was not yet able to measure the fluxes with acceptable precision, we discuss possible modifications to improve system performance.

Koch, G.; Gibert, F.; Davis, K.; Ismail, S.; Singh, U.

2007-12-01

257

Coherence between atmospheric teleconnections, Great Lakes water levels, and regional climate  

NASA Astrophysics Data System (ADS)

We investigated the frequency domain relationships between four atmospheric teleconnections (Trans-Niño Index TNI, Pacific Decadal Oscillation PDO, Northern Annular Mode/Arctic Oscillation Index NAM/AO, and Pacific/North American PNA pattern) and water levels in the Great Lakes from 1948 to 2002 by quantifying the coherence between these time series. The levels in all Great Lakes are significantly correlated with the TNI in the frequency range (3-7) -1 cycles year -1, and with the PDO in interdecadal frequencies. The levels in Lakes Superior, Michigan, and Erie are significantly correlated with the PNA pattern in interdecadal frequencies, and the levels in all Great Lakes are significantly correlated with the NAM/AO in interannual frequencies. We investigated also the coherence, or "climate link", between atmospheric teleconnections and the Great Lakes regional climate, namely precipitation, evaporation, air temperature, and connecting channel flows, and the coherence, or "hydrologic link" between regional climate and lake levels. The effect of the teleconnections on lake levels is mostly transmitted through the "climate links" and the "hydrologic links", particularly through the channel inflows to Lakes Michigan, Erie, and Ontario. Connecting channel flows depend on the cumulative effect of upstream lakes and their watersheds and transmit interannual and interdecadal signals better than precipitation, evaporation, and air temperature.

Ghanbari, Reza Namdar; Bravo, Hector R.

2008-10-01

258

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

259

Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET). Hanford Environmental Dose Reconstruction Project  

SciTech Connect

The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses that individuals may have received from operations at the Hanford Site since 1944. This report deals specifically with the atmospheric transport model, Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET). RATCHET is a major rework of the MESOILT2 model used in the first phase of the HEDR Project; only the bookkeeping framework escaped major changes. Changes to the code include (1) significant changes in the representation of atmospheric processes and (2) incorporation of Monte Carlo methods for representing uncertainty in input data, model parameters, and coefficients. To a large extent, the revisions to the model are based on recommendations of a peer working group that met in March 1991. Technical bases for other portions of the atmospheric transport model are addressed in two other documents. This report has three major sections: a description of the model, a user`s guide, and a programmer`s guide. These sections discuss RATCHET from three different perspectives. The first provides a technical description of the code with emphasis on details such as the representation of the model domain, the data required by the model, and the equations used to make the model calculations. The technical description is followed by a user`s guide to the model with emphasis on running the code. The user`s guide contains information about the model input and output. The third section is a programmer`s guide to the code. It discusses the hardware and software required to run the code. The programmer`s guide also discusses program structure and each of the program elements.

Ramsdell, J.V. Jr.; Simonen, C.A.; Burk, K.W.

1994-02-01

260

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

261

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

262

A New Mass Spectrometer for Upper Atmospheric Measurements in the Auroral Region  

NASA Astrophysics Data System (ADS)

We have previously presented a new rocket-borne time-of-flight mass spectrometer (TOF-MS) for measurements in the mesosphere / lower thermosphere (MLT). Traditionally, mass spectrometry in the MLT has been difficult, mainly due to the elevated ambient pressures of the MLT and high speeds of a sounding rocket flight, which affect the direct sampling of the ambient atmosphere and spatial resolution. The TOF-MS is a versatile, inherently adaptable, axial-sampling instrument, capable of operating in a traditional TOF mode or in a multiplexing Hadamard-transform mode where high spatial resolution is desired. To minimize bow shock effects at low altitudes (~70-110km), the ram surface of the TOF-MS can be cryogenically cooled using liquid He to adsorb impinging gas particles. The vacuum pumping system for the TOF-MS is tailored to the specific mission and instrument configuration. Depending on the instrument gas load and operating altitude, cryo, miniature turbo pump or getter-based pumping systems may be employed. Terrestrial TOF-MS instruments often employ a reflectron, essentially an ion-mirror, to improve mass resolving power and compensate for the thermal velocity distribution of particles being measured. The TOF-MS can be arranged in either a simple linear or reflectron configuration. Simulations and modeling are used to compare instrument mass resolution for linear and reflectron configurations for several variable conditions including vehicle velocity and ambient temperature, ultimately demonstrating the potential to make rocket-borne mass spectrometry measurements with unit-mass resolution up to at least 48 amu. Preliminary analyses suggest that many species of interest (including He, CO2, O2, O2+ , N2, N2+, and NO+) can be measured with an uncertainty below 10% relative standard deviation on a sounding rocket flight. We also present experimental data for a laboratory prototype linear TOF-MS. Experimental data is compared to simulation and modeling efforts to validate and confirm instrument performance and capability. Two proposed rocket campaigns for investigations of the auroral region include the TOF-MS. By making accurate composition measurements of the neutral atmosphere from 70 to 120km, Mass Spectrometry of the Turbopause Region (MSTR) aims to improve the accuracy of temperature measurements in the turbopause region, improve the MSIS model atmosphere and examine the transition from the turbulently mixed lower atmosphere to the diffusive equilibrium of the upper atmosphere. The ROCKet-borne STorm Energetics of Auroral Dosing in the E-region (ROCK-STEADE) mission will study energy transfer in the E-region during an aurora by examining auroral emissions and measuring concentrations of neutrals and ions. The instrument suite for ROCK-STEADE includes two mass spectrometers, one each to measure neutrals and ions in the altitude range of 70 - 170km. The ability of the TOF-MS instrument to make accurate measurements will greatly aid in better understanding the MLT.

Everett, E. A.; Dyer, J. S.; Watson, M.; Sanderson, W.; Schicker, S.; Work, D.; Mertens, C. J.; Bailey, S. M.; Syrstad, E. A.

2011-12-01

263

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

264

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

265

Data Assimilation and Regional Forecasts Using Atmospheric InfraRed Sounder (AIRS) Profiles  

NASA Technical Reports Server (NTRS)

In data sparse regions, remotely-sensed observations can be used to improve analyses, which in turn should 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 an accuracy comparable to that of radiosondes. The purpose of this paper is to describe a procedure to optimally assimilate AIRS thermodynamic profiles--obtained from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm-into a regional configuration of the Weather Research and Forecasting (WRF) model using WRF-Var. The paper focuses on development of background error covariances for the regional domain and background field type, a methodology for ingesting AIRS profiles as separate over-land and over-water retrievals with different error characteristics, and utilization of level-by-level quality indicators to select only the highest quality data. The assessment of the impact of the AIRS profiles on WRF-Var analyses will focus on intelligent use of the quality indicators, optimized tuning of the WRF-Var, and comparison of analysis soundings to radiosondes. The analyses will be used to conduct a month-long series of regional forecasts over the continental U.S. The long-tern1 impact of AIRS profiles on forecast will be assessed against verifying radiosonde and stage IV precipitation data.

Chou, Shih-Hung; Zavodsky, Bradley; Jedlovec, Gary

2009-01-01

266

Data Assimilation and Regional Forecasts using Atmospheric InfraRed Sounder (AIRS) Profiles  

NASA Technical Reports Server (NTRS)

In data sparse regions, remotely-sensed observations can be used to improve analyses, which in turn should 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 an accuracy comparable to that of radionsondes. The purpose of this poster is to describe a procedure to optimally assimilate AIRS thermodynamic profiles, obtained from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm, into a regional configuration of the Weather Research and Forecasting (WRF) model using WRF-Var. The poster focuses on development of background error covariances for the regional domain and background field type, a methodology for ingesting AIRS profiles as separate over-land and over-water retrievals with different error characteristics, and utilization of level-by-level quality indicators to select only the highest quality data. The assessment of the impact of the AIRS profiles on WRF-Var analyses will focus on intelligent use of the quality indicators, optimized tuning of the WRF-Var, and comparison of analysis soundings to radiosondes. The analyses are used to conduct a month-long series of regional forecasts over the continental U.S. The long-term impact of AIRS profiles on forecast will be assessed against NAM analyses and stage IV precipitation data.

Zabodsky, Brad; Chou, Shih-Hung; Jedlovec, Gary J.

2009-01-01

267

Atmospheric Transport of Arid Aerosol from Desert Regions of Central Asia  

NASA Astrophysics Data System (ADS)

Investigation of atmospheric transport of arid aerosol from Central Asia was held within the ISTC project 3715. Particular attention was paid to the removal of aerosol from the Aral Sea region and its further transport, because aerosol and pollutants emission from Central Asia affect the airspace of the entire Asian continent. At the same time measurements of aerosols in the atmosphere of Central Asia are holding in a small number of stations, and currently available data are insufficient to define the initial conditions and/or verification of models of long-range transport. To identify sources of pollution transported from Central Asia, in Kyrgyzstan measurement and sampling of air were organized: at the station on the northern slope of the Kirgiz Range, 30 km south of Bishkek, at an altitude of 1700 m above sea level (Bishkek Site, 42,683N; 74,694E ), and on permanent alpine Teploklyuchenka lidar station in the Central Tien Shan at an altitude of 2000 m above sea level (Lidar Site, 42,467N; 78,533E). The chemical analysis of collected aerosol and soils samples was carried out. Measurements of aerosol at these stations have been merged with the simulation of the trajectories of air masses in the study region and with the satellite (the Terra and Aqua satellites) observations of aerosol optical thickness in this region. Satellite data for the region 43-47 N, and 58-62 E (Aral Sea) from April 2008 to September 2009 were analyzed. The moments were selected, when the value of aerosol optical thickness (AOT) was greatest (more than 0.5), and the transport from the Aral Sea region to the observation sites took place. For each of these days, the forward trajectories, which started at 6 points within the region, were calculated using the HYSPLIT model. The days, on which the trajectories reached the BISHKEK and LIDAR sites, were determined from the data obtained. Calculations on the basis of the RAMS model were performed for these days. These calculations were performed using a grid of 160*120*30 points. The obtained meteorological fields were used in the HYPACT model; the source of Lagrangian particles was located over the Aral Sea region. As the result for 2008 11 days were detected when aerosol from the Aral Sea was actively transported to the observation sites. Comparative chemical analysis of aerosol samples at the stations of observation and soil samples from the Aral Sea region would confirm the presence of emissions and regional transport. It should be noted that the main source of aerosol in Central Asia is Taklamakan desert. Average value and AOT variability over it several times higher than corresponding AOT values over the rest of the region. The greatest variability aerosol over Taklamakan observed from late March to mid-May. For example, on April 22, 2008 average of the AOT in cell 5° x 5° over the western part of Taklamakan - value reached 3,171. AOT virtually throughout the region positively correlated with AOT over Taklamakan desert. The most noticeable effect makes an aerosol of Taklamakan found in the south-east Kyrgyzstan, Tajikistan in the east and north of the Tibetan highlands. The impact of the Aral Sea area is restricted significantly less. In doing so, AOT in the central part of the region reveals a weak negative correlation with the AOT over the Aral Sea.

Chen, Boris; Solomon, Paul; Sitnov, Sergei; Grechko, Evgeny; Maximenkov, Leonid; Artamonova, Maria; Pogarski, Fedor

2010-05-01

268

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

269

Evidence that local land use practices influence regional climate, vegetation, and stream flow patterns in adjacent natural areas  

USGS Publications Warehouse

We present evidence that land use practices in the plains of Colorado influence regional climate and vegetation in adjacent natural areas in the Rocky Mountains in predictable ways. Mesoscale climate model simulations using the Colorado State University Regional Atmospheric Modelling System (RAMS) projected that modifications to natural vegetation in the plains, primarily due to agriculture and urbanization, could produce lower summer temperatures in the mountains. We corroborate the RAMS simulations with three independent sets of data: (i) climate records from 16 weather stations, which showed significant trends of decreasing July temperatures in recent decades; (ii) the distribution of seedlings of five dominant conifer species in Rocky Mountain National Park, Colorado, which suggested that cooler, wetter conditions occurred over roughly the same time period; and (iii) increased stream flow, normalized for changes in precipitation, during the summer months in four river basins, which also indicates cooler summer temperatures and lower transpiration at landscape scales. Combined, the mesoscale atmospheric/land-surface model, short-term in regional temperatures, forest distribution changes, and hydrology data indicate that the effects of land use practices on regional climate may overshadow larger-scale temperature changes commonly associated with observed increases in CO2 and other greenhouse gases.

Stohlgren, T.J.; Chase, T.N.; Pielke, R.A., Sr.; Kittel, T.G.F.; Baron, J.S.

1998-01-01

270

Atmospheric correction using near-infrared bands for satellite ocean color data processing in the turbid western Pacific region.  

PubMed

A regional near-infrared (NIR) ocean normalized water-leaving radiance (nL(w)(?)) model is proposed for atmospheric correction for ocean color data processing in the western Pacific region, including the Bohai Sea, Yellow Sea, and East China Sea. Our motivation for this work is to derive ocean color products in the highly turbid western Pacific region using the Geostationary Ocean Color Imager (GOCI) onboard South Korean Communication, Ocean, and Meteorological Satellite (COMS). GOCI has eight spectral bands from 412 to 865 nm but does not have shortwave infrared (SWIR) bands that are needed for satellite ocean color remote sensing in the turbid ocean region. Based on a regional empirical relationship between the NIR nL(w)(?) and diffuse attenuation coefficient at 490 nm (K(d)(490)), which is derived from the long-term measurements with the Moderate-resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, an iterative scheme with the NIR-based atmospheric correction algorithm has been developed. Results from MODIS-Aqua measurements show that ocean color products in the region derived from the new proposed NIR-corrected atmospheric correction algorithm match well with those from the SWIR atmospheric correction algorithm. Thus, the proposed new atmospheric correction method provides an alternative for ocean color data processing for GOCI (and other ocean color satellite sensors without SWIR bands) in the turbid ocean regions of the Bohai Sea, Yellow Sea, and East China Sea, although the SWIR-based atmospheric correction approach is still much preferred. The proposed atmospheric correction methodology can also be applied to other turbid coastal regions. PMID:22274419

Wang, Menghua; Shi, Wei; Jiang, Lide

2012-01-16

271

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

272

Influence of processing gases on the properties of cold atmospheric plasma SiOxCy coatings  

NASA Astrophysics Data System (ADS)

Thin layers of SiOxCy (y = 4-x and 3 ? x ? 4) were applied using a cold atmospheric plasma torch on glass substrates. The aim was to investigate using Atomic Force Microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (Tof-Sims) the influence of the gases used on the morphology and composition of the deposits. A hexamethyldisilane (HMDS) precursor was injected in post-discharge in an air or nitrogen plasma using a carrier gas (air or nitrogen) and was applied on the substrate previously pre-treated by an air or nitrogen plasma. The carrier gas and plasma gas flows and the distance between the substrate and the plasma torch, the scanning speed, and the precursor flows were kept constant during the study. The gas used during activation pre-treatment showed no particular influence on the characteristics of the deposit. When air is used both as plasma and carrier gas, the coating layer is thicker (96 nm) than when nitrogen is used (64 nm). It was also evidenced that the gas carrying the precursor has little influence on the hydrophobicity of the coating, contrary to the plasma gas. The latter significantly influences the surface characteristics of the coatings. When air is used as plasma gas, a compact coating layer is obtained and the surface has a water contact angle (WCA) of 82°. When nitrogen is used, the deposit is more hydrophobic (WCA of 100°) and the deposit morphology is different. This increase in hydrophobicity could be correlated to the increase of Sisbnd Osbnd C bonds in the upper surface layers evidenced by XPS analyzes. This observation was then confirmed by Tof-Sims analyzes carried out on these thin layers. A uniform distribution of Carbons in the siloxane coating could also be observed using Tof-Sims 2D reconstruction images of cross sections of the deposited layers.

Hamze, H.; Jimenez, M.; Deresmes, D.; Beaurain, A.; Nuns, N.; Traisnel, M.

2014-10-01

273

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

274

Complex Patterns in Climate and Atmospheric Nitrogen Deposition Influence Rocky Mountain Ecosystems  

NASA Astrophysics Data System (ADS)

Long-term monitoring of physical and biogeochemical characteristics in Loch Vale watershed, Rocky Mountain National Park, has revealed complicated patterns in temperature, precipitation, and atmospheric nitrogen deposition. July mean and maximum temperatures have increased since 1985 by 0.1-0.2 ° C, while March mean and maximum temperatures became 0.1-0.3 ° C colder. There is no long-term trend in annual or monthly precipitation; annual totals range 75-140 cm yr-1. Atmospheric N deposition has increased approximately 2% yr-1 since 1985, and there are strong upward trends in July and September deposition. A combination of observations, ecosystem modeling (DayCent-Chem model), and structural equation modeling (SEM) suggests this alpine/subalpine catchment is responding physically, biologically, and chemically. Observed stream discharge was greater than measured precipitation in several recent years, indicating melt from glacier ice contributes to flow. Model results suggest a strong increase in alpine microbial activity and plant N uptake, and a moderate increase in forest microbial activity driven by increased temperatures and increased N deposition. Alpine lichen activity appears to also have been significantly stimulated. There has been a significant increase in observed stream nitrogen concentrations and flux. Annual mean stream N concentrations in alpine/subalpine Loch Vale watershed of Rocky Mountain National Park have increased from approximately 1.0 to 1.5 mg NO3 L-1 between 1991 and 2005; the annual amplitude has also increased. Mean annual N efflux from the catchment doubled between 1991 and 2005. SEM suggests N loss from Loch Vale appears to result most strongly from the combined influence of temperature and precipitation on stream flow, and secondarily from the influence of terrestrial nitrogen cycling.

Baron, J. S.; Schmidt, T.; Hartman, M. D.; Enders, S. K.; Pagani, M.; Wolfe, A. P.; Krcmarik, A.

2007-12-01

275

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

276

Influence of secondary formation on atmospheric occurrences of oxygenated polycyclic aromatic hydrocarbons in airborne particles  

NASA Astrophysics Data System (ADS)

Temporal and spatial variations in concentrations of particle-associated polycyclic aromatic hydrocarbons (PAHs) and their nitrated and oxygenated derivatives (nitro-PAHs and oxy-PAHs) were investigated to assess the influence of secondary formation on atmospheric occurrences of oxy-PAHs associated with particulate matter in downtown Tokyo, Japan. The daily variation in concentration of 1,8-naphthalic anhydride (1,8-NA) in summer 2007 was similar to that for 2-nitrofluoranthene (2-NF), a representative secondary formed nitro-PAH, while the variation for benzanthrone (BA) was similar to PAHs. In addition, the concentrations of polycyclic aromatic compounds (PACs) associated with airborne particulate matter decreased in the order of PAHs > BA > 9-fluorenone (9-FO) or 9,10-anthraquinone (9,10-AQ) > 1,8-NA with an increase in distance from the roadside, whereas 2-NF was constant. These results suggest that a considerable fraction of some oxy-PAHs such as 1,8-NA associated with airborne particulate matter in downtown Tokyo originates from atmospheric secondary formation.

Kojima, Yuki; Inazu, Koji; Hisamatsu, Yoshiharu; Okochi, Hiroshi; Baba, Toshihide; Nagoya, Toshio

2010-08-01

277

Climate-induced variability of sea level in Stockholm: Influence of air temperature and atmospheric circulation  

NASA Astrophysics Data System (ADS)

This study is focused on climate-induced variation of sea level in Stockholm during 1873 1995. After the effect of the land uplift is removed, the residual is characterized and related to large-scale temperature and atmospheric circulation. The residual shows an overall upward trend, although this result depends on the uplift rate used. However, the seasonal distribution of the trend is uneven. There are even two months (June and August) that show a negative trend. The significant trend in August may be linked to fresh water input that is controlled by precipitation. The influence of the atmospheric conditions on the sea level is mainly manifested through zonal winds, vorticity and temperature. While the wind is important in the period January May, the vorticity plays a main role during June and December. A successful linear multiple-regression model linking the climatic variables (zonal winds, vorticity and mean air temperature during the previous two months) and the sea level is established for each month. An independent verification of the model shows that it has considerable skill in simulating the variability.

Chen, Deliang; Omstedt, Anders

2005-09-01

278

Changes in atmospheric CO2 influence the allergenicity of Aspergillus fumigatus.  

PubMed

Increased susceptibility to allergies has been documented in the Western world in recent decades. However, a comprehensive understanding of its causes is not yet available. It is therefore essential to understand trends and mechanisms of allergy-inducing agents, such as fungal conidia. In this study, we investigated the hypothesis that environmental conditions linked to global atmospheric changes can affect the allergenicity of Aspergillus fumigatus, a common allergenic fungal species in indoor and outdoor environments and in airborne particulate matter. We show that fungi grown under present-day CO2 levels (392 ppm) exhibit 8.5 and 3.5 fold higher allergenicity compared to fungi grown at preindustrial (280 ppm) and double (560 ppm) CO2 levels, respectively. A corresponding trend is observed in the expression of genes encoding for known allergenic proteins and in the major allergen Asp f1 concentrations, possibly due to physiological changes such as respiration rates and the nitrogen content of the fungus, influenced by the CO2 concentrations. Increased carbon and nitrogen levels in the growth medium also lead to a significant increase in the allergenicity. We propose that climatic changes such as increasing atmospheric CO2 levels and changes in the fungal growth medium may impact the ability of allergenic fungi such as A. fumigatus to induce allergies. PMID:23568517

Lang-Yona, Naama; Levin, Yishai; Dannemiller, Karen C; Yarden, Oded; Peccia, Jordan; Rudich, Yinon

2013-08-01

279

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

280

Effects of atmospheric pollution on lichen biodiversity (LB) in a Mediterranean region (Liguria, northwest Italy).  

PubMed

The effects of air pollution on lichen biodiversity (LB) were monitored in Liguria (northwest Italy). A systematic sampling strategy was adopted in order to avoid the influence of spatial autocorrelation on the results. An eight LB class scale permitted to point out the levels of naturality/alteration in the region. The comparison of these results with the ones obtained by mean of physico-chemical methodologies shows a good accordance. The results of this study suggest the possibility of designing an integrated monitoring network, in which biological monitoring will allow to estimate the level of alteration in remote areas, which account for most of this region and which are currently not covered by measurements with automatic systems. PMID:11996383

Giordani, Paolo; Brunialti, Giorgio; Alleteo, Dario

2002-01-01

281

Water Vapor Tacers as Diagnostics of the Regional Atmospheric Hydrologic Cycle  

NASA Technical Reports Server (NTRS)

Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle, especially in North America where moisture transport and local evaporation are important sources of water for precipitation. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. All evaporative sources of water are accounted for by tracers, and the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The Geostationary Operational Environmental Satellites General Circulation Model (GEOS GCM) is used to simulate several summer periods to determine the source regions of precipitation for the United States and India. Using this methodology, a detailed analysis of the recycling of water, interannual variability of the sources of water and links to the Great Plains low-level jet and North American monsoon will be presented. Potential uses in GCM sensitivity studies, predictability studies and data assimilation especially regarding the North American monsoon and GEWEX America Prediction Project (GAPP) will be discussed.

Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

2000-01-01

282

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

283

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

284

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

285

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

286

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

287

Influence of helium mole fraction distribution on the properties of cold atmospheric pressure helium plasma jets  

NASA Astrophysics Data System (ADS)

The influence of helium mole fraction distribution in air on the cold atmospheric plasma jets excited by 1.5 kHz rectangular high voltage pulse is studied in this work. Computational fluid dynamics (CFD) with incorporation of large eddy simulation (LES) model is used to simulate the helium mole fraction distribution in air under the helium flow from laminar to turbulent regime with increasing helium outlet velocity. Numerical simulation results are combined with experimental results in order to determine the influence of helium distribution on the cold plasma jets. It reveals that the structure of the helium distribution caused by diffusion or by turbulent mixing in turbulent regime determines the characteristics of the cold plasma jets. On the other hand, the curves of plasma jet length (L) versus helium outlet velocity (V) at different jet diameters (D) are unified in a map of jet Reynolds number (Re = ?He.V.D/?He, where ?He is the helium viscosity constant) versus dimensionless plasma jet length (l = L/D). The map is allowed to predict the flow pattern of helium jet in order to estimate and control the plasma jet length at different jet diameters.

Xiong, Ranhua; Xiong, Qing; Nikiforov, Anton Yu.; Vanraes, Patrick; Leys, Christophe

2012-08-01

288

A fully coupled regional atmospheric numerical model for integrated air quality and weather forecasting.  

NASA Astrophysics Data System (ADS)

A new numerical modelling tool devoted to local and regional studies of atmospheric chemistry from surface to the lower stratosphere designed for both operational and research purposes will be presented. This model is based on the limited-area model CATT-BRAMS (Coupled Aerosol-Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System, Freitas et al. 2009, Longo et al. 2010) which is a meteorological model (BRAMS) including transport processes of gaseous and aerosols (CATT model). BRAMS is a version of the RAMS model (Walko et al. 2000) adapted to better represent tropical and subtropical processes and several new features. CATT-BRAMS has been used operationally at CPTEC (Brazilian Center for Weather Prediction and Climate Studies) since 2003 providing coupled weather and air quality forecast. In the Chemistry-CATT-BRAMS (called hereafter CCATT-BRAMS) a chemical module is fully coupled to the meteorological/tracer transport model CATT-BRAMS. This module includes gaseous chemistry, photochemistry, scavenging and dry deposition. The CCATT-BRAMS model takes advantages of the BRAMS specific development for the tropics/subtropics and of the recent availability of preprocessing tools for chemical mechanisms and of fast codes for photolysis rates. Similarly to BRAMS this model is conceived to run for horizontal resolutions ranging from a few meters to more than a hundred kilometres depending on the chosen scientific objective. In the last decade CCATT-BRAMS has being broadly (or extensively) used for applications mainly over South America, with strong emphasis over the Amazonia area and the main South American megacities. An overview of the model development and main applications will be presented.

Freitas, S. R.; Longo, K. M.; Marecal, V.; Pirre, M.; Gmai, T.

2012-04-01

289

Ambient concentrations of atmospheric ammonia, nitrogen dioxide and nitric acid in an intensive agricultural region  

NASA Astrophysics Data System (ADS)

The spatial and temporal distribution of ambient atmospheric gaseous reactive nitrogen (Nr) species concentrations (ammonia [NH3], nitrogen dioxide [NO2] and nitric acid [HNO3]) were measured at the field scale in an intensive agricultural region in southern Ontario, Canada. Atmospheric concentrations were measured with the Willems badge diffusive passive sampler (18 sites for NH3, 9 sites for NO2 and HNO3) for one year (April 2010-March 2011; under a two week measurement frequency) within a 15 km × 15 km area. Dry deposition was calculated using the inferential method and estimated across the entire study area. The spatial distribution of emission sources associated with agricultural activity resulted in high spatial variability in annual average ambient NH3 concentrations (<3->8 ?g m-3 within a 2 km distance, coefficient of variation ˜50%) and estimated dry deposition (4-13 kg N ha-1 yr-1) between sample sites. In contrast, ambient concentrations and deposition of both NO2 (˜5.2->6.5 ?g m-3; 1.0-1.5 kg N ha-1 yr-1) and HNO3 (0.6-0.7 ?g m-3; 0.5-1 kg N ha-1 yr-1) had low variability (coefficient of variation <10%). The observed NH3 concentrations accounted for ˜70% of gaseous Nr dry deposition. High NH3 concentrations suggest that reduced nitrogen species (NHx) will continue to make up an increasing fraction of Nr deposition within intensive agricultural regions in southern Ontario under legislated nitrogen oxide emission reductions. Further, estimated total inorganic Nr deposition (15-28 kg N ha-1 yr-1) may lead to potential changes in soil processes, nutrient imbalance and altered composition of mycorrhiza and ground vegetation within adjacent semi-natural ecosystems (estimated at ˜10% of the study area).

Zbieranowski, Antoni L.; Aherne, Julian

2013-05-01

290

Regional assessment of atmospheric organic and black carbon in South Africa  

NASA Astrophysics Data System (ADS)

At present limited data exists for atmospheric black carbon (BC) and organic carbon (OC) in South Africa. In this paper BC and OC concentrations were explored in terms of spatial and temporal patterns, mass fractions of BC and OC of the overall aerosol mass, as well as linked to possible sources. PM10 and PM2.5 samples were collected at five sampling sites in South Africa operated within the DEBITS IDAF network, i.e. Louis Trichardt, Skukuza, Vaal Triangle, Amersfoort and Botsalano, with MiniVol samplers. Samples were analysed with a Thermal/Optical Carbon analyser. OC were higher than BC concentrations at all sites in both size fractions. Most OC and BC were present in the PM2.5 fraction. OC/BC ratios reflected the location of the different DEBITS sites, with sites in or close to anthropogenic source regions having the lowest OC/BC ratios, while background sites had the highest OC/BC ratios. The OC mass fraction percentage varied between 1% and 24%, while the BC mass fraction ranged between 1 and 12 %. The highest OC mass fraction was found at Skukuza in the Kruger National Park, which was attributed to both natural sources and anthropogenic impacts from a dominant path of air mass movement from the anthropogenic industrial hub of South Africa. The highest mass fraction of BC was found at the Vaal Triangle situated within an region highly impacted by industry and household combustion for space heating and cooking. A relatively distinct seasonal pattern was observed, with higher OC and BC concentrations determined between May and October, which coincide with the dry season in the interior of South Africa. Positive correlations between OC and BC concentrations with the distance from back trajectories passing over veld fires were observed, indicating that veld fires contribute significantly to atmospheric OC and BC during the burning months.

Gideon van Zyl, Pieter; Maritz, Petra; Beukes, Johan Paul; Liousse, Cathy; Galy-Lacaux, Corinne; Castéra, Pierre; Venter, Andrew; Pienaar, Kobus

2014-05-01

291

Mapping the regional influence of genetics on brain structure variability --A Tensor-Based Morphometry study  

E-print Network

is genetically determined. As part of an MRI study that will scan 1150 twins, we applied Tensor-Based Morphometry the understanding of the influence of genetics on anatomical variability. Twins have been studied with quantitativeMapping the regional influence of genetics on brain structure variability -- A Tensor

Thompson, Paul

292

UNCORRECTEDPROOF 1 Mapping the regional influence of genetics on brain structure  

E-print Network

of the influence of genetics on anatomical variability. 46 Twins have been studied with quantitative genetic modelsUNCORRECTEDPROOF 1 Mapping the regional influence of genetics on brain structure 2 variability of Queensland, Brisbane, Queensland, 4072, Australia 9 d Genetic Epidemiology Lab, Queensland Institute

Thompson, Paul

293

Influence of geomagnetic disturbances on atmospheric electric field (Ez) variations at high and middle latitudes  

NASA Astrophysics Data System (ADS)

The variations of the vertical atmospheric electric field (Ez) represent the state of the global atmospheric electric circuit, which is controlled by the world thunderstorm activity and by magnetosphere-ionosphere disturbances as well. Here we present a synthesis of our main results of the effects of the geomagnetic disturbances on the Ez variations, measured at the Earth?s surface at high and middle latitudes, which were previously published by Kleimenova et al. (2008, 2010). We studied the high latitude geomagnetic substorm effects on the Ez variations on the base of the continue Ez registrations at the polar station Hornsund (Spitsbergen). This station can map into the polar cap, auroral oval or near the border between these structures in dependence on the local time and the level of the geomagnetic activity. The high-latitude Ez variations associated with the substorm activity have been established. It was found that the Ez deviations were positive (Ez values increase) in the local morning and negative ones (Ez values decrease) in the local evening. We speculate that the direction of the Ez excursion depends on the station location relative to the positive or negative vortex of the polar ionospheric plasma convection. The Ez variations at the mid-latitude station ?wider (near Warsaw) have been studied during 14 magnetic storms. To avoid the meteorological influences on the Ez measurements we used only the Ez data, obtained under the “fair weather” conditions. For the first time the main phase effect of all mentioned above magnetic storms was established in the mid-latitude atmospheric electricity variations. The strong daytime Ez negative excursions (Ez value decreases) were found in association with the simultaneous night-side magnetospheric substorm developing during the studied magnetic storms. The considered Ez deviations could be results an interplanetary electric field penetration into the magnetosphere. Another plausible reason could be related to the common ionosphere conductivity increasing due to substorm energetic electron precipitation, modifying the high-latitude ionospheric part of the global atmospheric electric circuit.

Kleimenova, N.; Kozyreva, O.; Michnowski, S.; Kubicki, M.

2013-07-01

294

Ice-ocean-atmosphere coupling in the Regional Arctic System Model  

NASA Astrophysics Data System (ADS)

This work demonstrates the sea ice model performance in the latest version of the Regional Arctic System Model (RASM), which is a fully coupled regional climate model developed by a group of U.S. institutions as a regional counterpart to the Community Earth System Model (CESM). RASM is comprised of the Parallel Ocean Program (POP), Los Alamos Sea Ice Model (CICE), Variable Infiltration Capacity (VIC) hydrology model and the Weather Research and Forecasting (WRF) Model. It uses the same coupling infrastructure as CESM, with important physics differences that we have found to be important in our high-resolution model. Model evaluations using SSM/I sea ice extent and concentration, ICESat sea ice thickness measurements, ice-ocean buoys, and satellite retrievals of sea ice drift and deformation, lead us to adjust the standard CESM Monin-Obukhov ice-ocean-atmospheric coupling and ice-ocean stress term used for coupling with POP-CICE at eddy-permitting resolution of 1/12 degree with the 50km resolution WRF and VIC models. Evaluation metrics based on scaling laws and wavelet techniques illustrate that 20-minute coupling produces deformation and drift statistics commensurate with high temporal and spatial resolution measurements. However, dynamical interactions are compromised when typical radiative settings are used as in stand-alone POP-CICE and WRF. This highlights the limitations of surface polar boundary conditions in stand-alone models relative to fully coupled interactions. Our results suggest that use of uncoupled models as testbeds for improved polar components of next-generation global Earth System Models may introduce biases into fully coupled systems, and these can be reduced using a regional coupled climate system model, such as RASM, as a testbed instead.

Roberts, A.; Brunke, M.; Cassano, J. J.; Craig, A.; Duvivier, A.; Hughes, M.; Maslowski, W.; Nijssen, B.; Osinski, R.

2013-12-01

295

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

296

Study of the near-wall-turbulent region of the high-Reynolds-number boundary layer using an atmospheric flow  

NASA Astrophysics Data System (ADS)

Data from the near-wall-turbulent region of the high-Reynolds-number atmospheric surface layer are used to analyse the attached-eddy model of wall turbulence. All data were acquired during near-neutral conditions at the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility located in the western Utah Great Salt Lake Desert. Instantaneous streamwise and wall-normal components of velocity were collected with a wall-normal array of two-component hot wires within the first 2 m above the surface of the salt flats. Streamwise and wall-normal turbulence intensities and spectra are directly compared to corresponding laboratory data and similarity formulations hypothesized from the attached-eddy model of wall turbulence. This affords the opportunity to compare results with Reynolds numbers varying over three orders of magnitude. The wall-normal turbulence-intensity similarity formulation is extended. The results show good support for the similarity arguments forwarded by the attached-eddy model as well as Townsend's (1956) Reynolds-number similarity hypothesis and lack of the ‘inactive’ motion influence on the wall-normal velocity component. The effects of wall roughness and the spread in the convection velocity due to this roughness are also discussed.

Kunkel, Gary J.; Marusic, Ivan

2006-02-01

297

On transient events in the upper atmosphere generated away of thunderstorm regions  

NASA Astrophysics Data System (ADS)

Experimental data on transient events in UV and Red-IR ranges obtained in the MSU missions "Unversitetsky-Tatiana" (wavelengths 300-400 nm) and "Unversitetsky-Tatiana-2" (wavelengths 300-400 nm and 600-800 nm), published by Garipov et al, in 2010 at COSPAR session http://www.cospar2010.org, at TEPA conference http://www.aragats.am/Conferences/tepa2010 and in 2011 by Sadovnichy et al, Solar System Research, 45, #1, 3-29 (2011); Vedenkin et al, JETP, v. 140, issue 3(9), 1-11 (2011) demonstrated existence of transients at large distances (up to thousands km) away of cloud thunderstorm regions. Those "remote" transients are short (1-5 msec) and are less luminous than the transients above thunderstorm regions. The ratio of Red-IR to UV photon numbers in those transients indicates high altitude of their origin (~70 km). Important observation facts are also: 1. a change of the exponent in transient distribution on luminosity Q ("-1" for photon numbers Q=1020 -1023 to "-2" for Q>1023), 2. a change of global distribution of transient with their luminosity (transients with Q>1023 are concentrated in equatorial range above continents, while transients with low luminosity are distributed more uniformly), 3. a phenomenon of transient sequences in one satellite orbit which is close to geomagnetic meridian. In the present paper phenomenological features of transients are explained in assumption that the observed transients have to be divided in two classes: 1. transients related to local, lower in the atmosphere, lightning at distance not more than hundreds km from satellite detector field of view in the atmosphere and 2. transients generated by far away lightning. Local transients are luminous and presumably are events called "transient luminous events" (TLE). In distribution on luminosity those events have some threshold Q~1023 and their differential luminosity distribution is approximated by power law exponent "-2". Remote transients have to be considered separately. Their origin may be related to electromagnetic pulses (EMP) or waves (whistler, EMW) generated by lightning. The EMP-EMW is transmitted in the ionosphere- ground channel to large distances R with low absorption. The part of EMP-EMW "visible" in the detector aperture diminishes with distance as R-1 due to observation geometry. The EMP-EMW triggers the electric discharge in the upper atmosphere (lower ionosphere, ~70 km). Estimates of resulting transients luminosity and their correlation with geomagnetic field are in progress.

Morozenko, V.; Garipov, G.; Khrenov, B.; Klimov, P.; Panasyuk, M.; Sharakin, S.; Zotov, M.

2011-12-01

298

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

299

Impact of the regional climate and substance properties on the fate and atmospheric long-range transport of persistent organic pollutants examples of DDT and ?-HCH  

NASA Astrophysics Data System (ADS)

A global multicompartment model which is based on a 3-D atmospheric general circulation model (ECHAM5) coupled to 2-D soil, vegetation and sea surface mixed layer reservoirs, is used to simulate the atmospheric transports and total environmental fate of dichlorodiphenyltrichloroethane (DDT) and ?-hexachlorocyclohexane (?-HCH, lindane). Emissions into the model world reflect the substance's agricultural usage in 1980 and 1990 and same amounts in sequential years are applied. Four scenarios of DDT usage and atmospheric decay and one scenario of ?-HCH are studied over a decade. The global environment is predicted to be contaminated by the substances within ca. 2 a (years). DDT reaches quasi-steady state within 3-4 a in the atmosphere and vegetation compartments, ca. 6 a in the sea surface mixed layer and near to or slightly more than 10 a in soil. Lindane reaches quasi-steady state in the atmosphere and vegetation within 2 a, in soils within 8 years and near to or slightly more than 10 a and in the sea surface mixed layer. The substances' differences in environmental behaviour translate into differences in the compartmental distribution and total environmental residence time, ?overall. ?overall?0.8 a for ?-HCH's and ?1.0-1.3 a for the various DDT scenarios. Both substances' distributions are predicted to migrate in northerly direction, 5-12° for DDT and 6.7° for lindane between the first and the tenth year in the environment. Cycling in various receptor regions is a complex superposition of influences of regional climate, advection, and the substance's physico-chemical properties. As a result of these processes the model simulations show that remote boreal regions are not necessarily less contaminated than tropical receptor regions. Although the atmosphere accounts for only 1% of the total contaminant burden, transport and transformation in the atmosphere is key for the distribution in other compartments. Hence, besides the physico-chemical properties of pollutants the location of application (entry) affects persistence and accumulation emphasizing the need for georeferenced exposure models.

Semeena, V. S.; Feichter, J.; Lammel, G.

2005-12-01

300

Impact of the regional climate and substance properties on the fate and atmospheric long-range transport of persistent organic pollutants - examples of DDT and ?-HCH  

NASA Astrophysics Data System (ADS)

A global multicompartment model which is based on a 3-D atmospheric general circulation model (ECHAM5) coupled to 2-D soil, vegetation and sea surface mixed layer reservoirs, is used to simulate the atmospheric transports and total environmental fate of dichlorodiphenyltrichloroethane (DDT) and ?-hexachlorocyclohexane (?-HCH, lindane). Emissions into the model world reflect the substance's agricultural usage in 1980 and 1990 and same amounts in sequential years are applied. Four scenarios of DDT usage and atmospheric decay and one scenario of ?-HCH are studied over a decade.

The global environment is predicted to be contaminated by the substances within ca. 2a (years). DDT reaches quasi-steady state within 3-4a in the atmosphere and vegetation compartments, ca. 6a in the sea surface mixed layer and near to or slightly more than 10a in soil. Lindane reaches quasi-steady state in the atmosphere and vegetation within 2a, in soils within 8 years and near to or slightly more than 10a and in the sea surface mixed layer. The substances' differences in environmental behaviour translate into differences in the compartmental distribution and total environmental residence time, ?overall. ?overall?0.8a for ?-HCH's and ?1.0-1.3 a for the various DDT scenarios. Both substances' distributions are predicted to migrate in northerly direction, 5-12° for DDT and 6.7° for lindane between the first and the tenth year in the environment. Cycling in various receptor regions is a complex superposition of influences of regional climate, advection, and the substance's physico-chemical properties. As a result of these processes the model simulations show that remote boreal regions are not necessarily less contaminated than tropical receptor regions. Although the atmosphere accounts for only 1% of the total contaminant burden, transport and transformation in the atmosphere is key for the distribution in other compartments. Hence, besides the physico-chemical properties of pollutants the location of application (entry) affects persistence and accumulation emphasizing the need for georeferenced exposure models.

Semeena, V. S.; Feichter, J.; Lammel, G.

2006-04-01

301

Atmospheres  

NASA Astrophysics Data System (ADS)

When high Al containing Fe alloys such as TRIP steels are exposed to atmospheres that contain N2 during re-heating, sub-surface nitrides form and these can be detrimental to mechanical properties. Nitride precipitation can be controlled by minimizing the access of the gaseous atmosphere to the metal surface, which can be achieved by a rapid growth of a continuous and adherent surface scale. This investigation utilizes a Au-image furnace attached to a confocal scanning microscope to simulate the annealing temperature vs time while Fe-Al alloys (with Al contents varying from 1 to 8 wt pct) are exposed to a O2-N2 atm with 10-6 atm O2. The heating times of 1, 10, and 100 minutes to the isothermal temperature of 1558 K (1285 °C) were used. It was found that fewer sub-surface nitride precipitates formed when the heating time was lowered and when Al content in the samples was increased. In the 8 wt pct samples, no internal nitride precipitates were present regardless of heating time. In the 3 and 5 wt pct samples, internal nitride precipitates were nearly more or less absent at heating times less than 10 minutes. The decrease in internal precipitates was governed by the evolving structure of the external oxide-scale. At low heating rates and/or low Al contents, significant Fe-oxide patches formed and these appeared to allow for ingress of gaseous N2. For the slow heating rates, ingress could have happened during the longer time spent in lower temperatures where non-protective alumina was present. As Al content in the alloy was increased, the external scale was Al2O3 and/or FeAl2O4 and more continuous and consequently hindered the N2 from accessing the metal surface. Increasing the Al content in the alloy had the effect of promoting the outward diffusion of Al in the alloy and thereby assisting the formation of the continuous external layer of Al2O3 and/or FeAl2O4.

Bott, June; Yin, Hongbin; Sridhar, Seetharaman

2014-12-01

302

Atmospheric solar absorption measurements in the 9 to 11 mu m region using a diode laser heterodyne spectrometer  

NASA Technical Reports Server (NTRS)

A tunable diode laser heterodyne radiometer was developed for ground-based measurements of atmospheric solar absorption spectra in the 8 to 12 microns spectral range. The performance and operating characteristics of this Tunable Infrared Heterodyne Radiometer (TIHR) are discussed along with atmospheric solar absorption spectra of HNO3, O3, CO2, and H2O in the 9 to 11 microns spectral region.

Harward, C. N.; Hoell, J. M., Jr.

1980-01-01

303

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

304

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

305

Titan's Hydrodynamically Escaping Atmosphere and the Structure of the Exobase Region  

NASA Astrophysics Data System (ADS)

In a previous paper (Strobel, Icarus, 193, 588-594, 2008), I have argued that the upper atmosphere of Titan is undergoing hydrodynamic escape as a high density, slow outward expansion, driven principally by solar UV heating by CH4 absorption. The hydrodynamic mass loss, currently at a rate ~ (4-5)× 1028amu s-1, is essentially CH4 and H2 escape (Cui et al. J. Geophys. Res. in press, 2008; Yelle et al. J. Geophys. Res., in press, 2008) and limited by available solar UV power. The slow hydrodynamic expansion solutions below the exobase must be matched to an escape model in the exosphere, and there is still considerably controversy on the acceleration mechanism to achieve escape speeds. From Cassini INMS data, the structure of the "exobase region" on Titan will be explored and demonstrated to not be a thin transition level to an instanteously collisionless exosphere, as is normally assumed, but rather an extended region of ~ 1000 km, which is quasi-collisional. Processes that may considerably increase the current mass loss rate will be discussed.

Strobel, D. F.

2008-12-01

306

Titan's Hydrodynamically Escaping Atmosphere and the Structure of the Exobase Region  

NASA Astrophysics Data System (ADS)

In a previous paper (Strobel, Icarus, 193, 588-594, 2008), I have argued that the upper atmosphere of Titan is undergoing hydrodynamic escape as a high density, slow outward expansion, driven principally by solar UV heating by CH4 absorption. The hydrodynamic mass loss, currently at a rate ~ 4-5) x 1028 amu/s, is essentially CH4 and H2 escape (Cui et al. J. Geophys. Res. in press, 2008; Yelle et al. J. Geophys. Res., in press, 2008) and limited by available solar UV power. The slow hydrodynamic expansion solutions below the exobase must be matched to an escape model in the exosphere, and there is still considerably controversy on the acceleration mechanism to achieve escape speeds. From Cassini INMS data, the structure of the "exobase region" on Titan will be explored and demonstrated to not be a thin transition level to an instanteously collisionless exosphere, as is normally assumed, but rather an extended region of ~ 1000 km, which is quasi-collisional. Processes that may considerably increase the current mass loss rate will be discussed.

Strobel, D. F.

2009-04-01

307

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

308

Atmospheric transmission in the UV and IR regions of the spectrum during the solar eclipse of July 31, 1981  

NASA Astrophysics Data System (ADS)

Ultraviolet measurements were made in the path of total eclipse at 51 deg 34 min N and 71 deg 28 min E (north of Tselinograd), using a filter photometer to obtain the relative intensities of disperse solar radiation from the zenith. Infrared measurements were made in the path of partial eclipse at a location east of Dushanbe, 38 deg 31 min N and 68 deg 50 min E. It is shown that the variations in atmospheric transmission in the two wavelength regions may be related to changes of state of the atmospheric aerosol, resulting from the variability of temperature and relative humidity in a vertical column of atmosphere.

Shukurov, A. Kh.; Emilenko, A. S.

1984-01-01

309

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

310

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

311

The influence of diel vertical migration on zooplankton transport and recruitment in an upwelling region: estimates  

E-print Network

-shore transport of organisms relative to passive or fixed-depth transport at the surface (Brockmann, 1979The influence of diel vertical migration on zooplankton transport and recruitment in an upwelling regions, DVM reduces the transport of organisms away from the region. It is unclear, however, what role

Pennington, J. Timothy

312

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

313

Precipitation extremes over Amazonia - atmospheric and oceanic associated features observed and simulated by HADGEM2-ES, CPTEC/INPE AGCM and Eta/CPTEC regional model  

NASA Astrophysics Data System (ADS)

Extreme monthly cases of precipitation (positive and negative anomalies) over Amazonia are analyzed to show the atmospheric and oceanic related features and the ability of CPTEC AGCM and HADGEM2-ES in simulating them. Humidity flux variability over the Tropical Atlantic region is analyzed related to the precipitation variability over Amazonia. Besides the Pacific Ocean influence, the Amazonia precipitation is affected by the Tropical Atlantic Ocean, both by the SST and atmospheric flux humidity. Correlations between Atlantic SST and Amazonia precipitation show that there are specific months and areas that are affected by SST anomalies. The extreme cases are obtained from the Standardized Precipitation Index (SPI) applied to monthly data in four areas of Amazonia: northwest, northeast, west and east areas. The period of analysis is 1981 to 2010 to GPCP observed precipitation and CPTEC/INPE AGCM. As this AGCM is the base of the Brazilian Model of Earth System, its behavior on the mechanisms leading to extremes over Amazonia, compared to observations is discussed. Projections of extremes over the region are analyzed with results from CMIP5 HADGEM2-ES during 2073-2099 compared to 1979-2005. The regional Eta CPTEC model is also analyzed in two periods: 1960 to 1990 and 2040 to 2070, with boundary conditions of CMIP3 HADCM3 A1B scenario. The relevance of this analysis is to identify changes in frequency and intensity of extremes in the Amazon region in a higher resolution than the global models.

Cavalcanti, I. F.

2013-05-01

314

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

315

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

316

Influence of modified atmosphere and varying time in storage on the irradiation sensitivity of Salmonella on sliced roma tomatoes  

Technology Transfer Automated Retrieval System (TEKTRAN)

Salmonella contamination of tomatoes is a recurrent food safety concern. Irradiation inactivates pathogens on fresh and fresh cut produce. However, the interaction of time in refrigerated storage and modified atmosphere packaging (MAP) may influence the response of pathogens to irradiation. Roma tom...

317

Influence of reduced carbon emissions and oxidation on the distribution of atmospheric CO2: Implications for inversion analyses  

E-print Network

Influence of reduced carbon emissions and oxidation on the distribution of atmospheric CO2 carbon emissions. We used TransCom3 annual mean simulations from three transport models to evaluate carbon emission and oxidation processes in deriving inversion estimates of CO2 surface fluxes. Citation

Krakauer, Nir Y.

318

Changes in Atmospheric CO2 Influence the Allergenicity of Aspergillus fumigatus fungal spore  

NASA Astrophysics Data System (ADS)

Increased allergic susceptibility has been documented without a comprehensive understanding for its causes. Therefore understanding trends and mechanisms of allergy inducing agents is essential. In this study we investigated whether elevated atmospheric CO2 levels can affect the allergenicity of Aspergillus fumigatus, a common allergenic fungal species. Both direct exposure to changing CO2 levels during fungal growth, and indirect exposure through changes in the C:N ratios in the growth media were inspected. We determined the allergenicity of the spores through two types of immunoassays, accompanied with genes expression analysis, and proteins relative quantification. We show that fungi grown under present day CO2 levels (392 ppm) exhibit 8.5 and 3.5 fold higher allergenicity compared to fungi grown at preindustrial (280 ppm) and double (560 ppm) CO2 levels, respectively. A corresponding trend is observed in the expression of genes encoding for known allergenic proteins and in the major allergen Asp f1 concentrations, possibly due to physiological changes such as respiration rates and the nitrogen content of the fungus, influenced by the CO2 concentrations. Increased carbon and nitrogen levels in the growth medium also lead to a significant increase in the allergenicity, for which we propose two different biological mechanisms. We suggest that climatic changes such as increasing atmospheric CO2 levels and changes in the fungal growth medium may impact the ability of allergenic fungi such as Aspergillus fumigatus to induce allergies. The effect of changing CO2 concentrations on the total allergenicity per 10^7 spores of A. fumigatus (A), the major allergen Asp f1 concentration in ng per 10^7 spores (B), and the gene expression by RT-PCR (C). The error bars represent the standard error of the mean.

Lang-Yona, N.; Levin, Y.; Dannemoller, K. C.; Yarden, O.; Peccia, J.; Rudich, Y.

2013-12-01

319

Modelling soil-plant-atmosphere interactions by coupling the regional weather model WRF to mechanistic plant models  

NASA Astrophysics Data System (ADS)

Climate change causes altering distributions of meteorological factors influencing plant growth and its interactions between the land surface and the atmosphere. Recent studies show, that uncertainties in regional and global climate simulations are also caused by lacking descriptions of the soil-plant-atmosphere system. Therefore, we couple a mechanistic soil-plant model to a regional climate and forecast model. The detailed simulation of the water and energy exchanges, especially the transpiration of grassland and forests stands, are the key features of the modelling framework. The Weather Research and Forecasting model (WRF) (Skamarock 2008) is an open source mesoscale numerical weather prediction model. The WRF model was modified in a way, to either choose its native, static land surface model NOAH or the mechanistic eco-system model Expert-N 5.0 individually for every single grid point within the simulation domain. The Expert-N 5.0 modelling framework provides a highly modular structure, enabling the development and use of a large variety of different plant and soil models, including heat transfer, nitrogen uptake/turnover/transport as well as water uptake/transport and crop management. To represent the key landuse types grassland and forest, we selected two mechanistic plant models: The Hurley Pasture model (Thornley 1998) and a modified TREEDYN3 forest simulation model (Bossel 1996). The models simulate plant growth, water, nitrogen and carbon flows for grassland and forest stands. A mosaic approach enables Expert-N to use high resolution land use data e.g. CORINE Land Cover data (CLC, 2006) for the simulation, making it possible to simulate different land use distributions within a single grid cell. The coupling results are analyzed for plausibility and compared with the results of the default land surface model NOAH (Fei Chen and Jimy Dudhia 2010). We show differences between the mechanistic and the static model coupling, with focus on the feedback effects of evapotranspiration, heat flow and radiation of thermodynamic values. Bossel, H. 1996. "TREEDYN3 forest simulation model." Ecological modelling 90 (3): 187-227. CLC, 2006. CORINE Land Cover 2006. http://www.eea.europa.eu/themes/landuse/interactive/clc-download. Accessed 16.12.2012. Fei Chen, and Jimy Dudhia. 2010. Coupling an Advanced Land Surface-Hydrology Model with the Penn State-NCAR MM5 Modeling System. Part II: Preliminary Model Validation. Research-article. February 25. Skamarock, W. C. 2008. "Coauthors 2008: A description of the Advanced Research WRF version 3." NCAR Tech. Note NCAR/TN-475+ STR. http://www.wrf-model.org/. Thornley, John. 1998. Grassland dynamics: an ecosystem simulation model. Wallingford,New York: CAB international.

Klein, C.; Hoffmann, P.; Priesack, E.

2012-04-01

320

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

321

The Relative Contributions of Low-Frequency Atmospheric Circulation, Chaotic Dynamics and Land-Atmosphere Feedbacks to the Variability of the Regional-Scale Water Balance  

NASA Astrophysics Data System (ADS)

In previous work, we developed a conceptually simple statistical-dynamical model of the regional-scale, coupled land-atmosphere water balance, which is formulated as a single stochastic differential equation (SDE) with soil moisture as its state variable. Under differing assumptions about the nature and strength of feedbacks to precipitation, we derived several approximate analytical solutions to the governing Fokker-Planck equation in the form of probability density functions of region-average soil moisture. Using NCEP/NCAR re-analysis data, estimates of potential evapotranspiration, and long-term observations of precipitation, streamflow, and soil moisture, parameter values were estimated for a 5-deg by 5-deg region encompassing the state of Illinois. It was then shown that precipitation-efficiency feedbacks can be significant contributors to the temporal variability of soil moisture, while precipitation recycling increases that variability by a negligible amount at the scale of the study region. In this paper, we first briefly review that earlier work. We next extend the analysis to several other domains within the central United States, thereby drawing conclusions about the strength of precipitation-efficiency feedbacks as a function of climate. We then use the modeling framework to examine the sources of persistence and interannual variability in both soil moisture and precipitation. It is shown that the autocorrelation function of daily precipitation contains a dominant short-memory component, as well as a low-grade, long-memory component. It is suggested that the former is due to chaotic atmospheric dynamics, while the latter is due to a combination of land-atmosphere feedbacks and low-frequency variability in advected atmospheric moisture flux. Finally, it is demonstrated the model is capable of distinguishing between all three sources of variability.

Kochendorfer, J. P.; Ramirez, J. A.

2006-05-01

322

An Investigation on the role of Planetary Boundary Layer Parameterization scheme on the performance of a hydrostatic atmospheric model over a Coastal Region  

NASA Astrophysics Data System (ADS)

As part of the ocean/land-atmosphere interaction, more than half of the total kinetic energy is lost within the lowest part of atmosphere, often referred to as the planetary boundary layer (PBL). A comprehensive understanding of the energetics of this layer and turbulent processes responsible for dissipation of kinetic energy within the PBL require accurate estimation of sensible and latent heat flux and momentum flux. In numerical weather prediction (NWP) models, these quantities are estimated through different surface-layer and PBL parameterization schemes. This research article investigates different factors influencing the accuracy of a surface-layer parameterization scheme used in a hydrostatic high-resolution regional model (HRM) in the estimation of surface-layer turbulent fluxes of heat, moisture and momentum over the coastal regions of the Indian sub-continent. Results obtained from this sensitivity study of a parameterization scheme in HRM revealed the role of surface roughness length (z_{0}) in conjunction with the temperature difference between the underlying ground surface and atmosphere above (?T = T_{G} - T_{A}) in the estimated values of fluxes. For grid points over the land surface where z_{0} is treated as a constant throughout the model integration time, ?T showed relative dominance in the estimation of sensible heat flux. In contrast to this, estimation of sensible and latent heat flux over ocean were found to be equally sensitive on the method adopted for assigning the values of z_{0} and also on the magnitudes of ?T.

Anurose, J. T.; Subrahamanyam, Bala D.

2012-07-01

323

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

NASA Astrophysics Data System (ADS)

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 south. Blocking the warm easterly winds from South America, the Andes help maintain the divergence and temperature inversion and, hence, the stratocumulus cloud deck over the southeast Pacific off South America. In an experiment where the Andean mountains are removed, the warm advection from the South American continent lowers the inversion height and reduces the low-level divergence offshore, leading to a significant reduction in cloud amount and an increase in solar radiation that reaches the sea surface.In March and early April 1999, the model simulates a double ITCZ in response to the seasonal warming on and south of the equator, in agreement with satellite observations. Under the same sea surface temperature forcing, the removal of the Andes prolongs the existence of the southern ITCZ for 3 weeks. Without the mountains, the intrusion of the easterlies from South America enhances the convergence in the lower atmosphere, and the transient disturbances travel freely westward from the continent. Both effects of the Andes removal favor deep convection south of the equator.The same sensitivity experiments are repeated with orography used in T42 global models, and the results confirm that an underrepresentation of the Andes reduces the stratus clouds in the cold season and prolongs the southern ITCZ in the warm season, with both acting to weaken the latitudinal asymmetry of eastern Pacific climate. The implications of these results for coupled modeling of climatic asymmetry are discussed.

Xu, Haiming; Wang, Yuqing; Xie, Shang-Ping

2004-02-01

324

LIDAR first results from the Oil Sands Region: A complex vertical atmosphere  

NASA Astrophysics Data System (ADS)

Environment Canada is using LIDAR technology to probe the complex vertical structure of the atmosphere over the oil sands region. This provided the critical vertical context for the interpretation of ground-based chemistry measurements and model verification and validation. In recent years, Environment Canada has designed an autonomous aerosol LIDAR system that can be deployed to remote areas such as the oil sands. The trailer that contains the LIDAR system includes a roof hatch assembly, basic meteorological tower, radar interlock system, climate control system and leveling stabilizers. A precipitation sensor is used to operate the roof hatch and three pan/tilt webcams capture sky conditions and monitor the Lidar system's health. A remote control interface is used to monitor all vital components of the system, including the ability to provide hard resets to the various electronic devices onboard. Every 10 seconds the system provides vertical aerosol profiles from near ground to 20 km. The LIDAR transmitter emits two wavelengths (1064nm and 532nm) and the detector assembly collects three channels (1064nm backscatter, 532nm backscatter and 532nm depolarization). The depolarization channel provided key information in identifying and discriminating the various aerosol layers aloft such as dust, forest fire plumes, industrial plume sources or ice crystals. It operates 24 hours a day, seven days a week except during precipitation events and when aircraft fly over the site. The system is operated remotely and the data are updated every hour to a website to allow near real-time capability. First results from an intensive field campaign will be presented. LIDAR false color plot showing the bottom 7 km of the atmosphere during a forest fire event. Note the forest fire plume is between 1.5 and 5 km.

Strawbridge, K. B.

2012-12-01

325

Bioactive and total endotoxins in atmospheric aerosols in the Pearl River Delta region, China  

NASA Astrophysics Data System (ADS)

Endotoxin, a toxic and pyrogenic substance in gram-negative bacteria in atmospheric aerosols was measured over a period of one year at Nansha, Guangzhou and Hong Kong in the Pearl River Delta region, China. Atmospheric aerosols were collected by high-volume samplers. The bioactive endotoxin levels in the samples were determined using the Limulus Amebocyte Lysate (LAL) assay after extraction with pyrogen-free water while the total endotoxin levels were measured by quantifying the biomarker, 3-hydroxy fatty acids (3-OHFAs) with GC-MS. Results showed that there was no significant difference (0.19 < p < 0.81) in the bioactive endotoxin level in PM 10 among sites (average concentrations ranged from 0.34 to 0.39 EU m -3). However, Hong Kong showed a significantly lower ( p < 0.05) total endotoxin level in PM 10 (average of 17.4 ng m -3) compared with Nansha's 29.4 ng m -3 and Guangzhou's 32.7 ng m -3. The bioactive endotoxins were found to be associated with the coarse mode (PM 2.5-10) of the particulates of natural origins while the total endotoxins were associated more with the fine mode (PM 2.5) of the particulates of anthropogenic origins. When normalized with particulate mass, the endotoxin loading is much higher in summer as a result of the increased growth of the bacteria when climatic conditions are favorable. The chemically determined total endotoxins were 3-4 orders of magnitude higher than the bioactive endotoxins quantified using the LAL assay. Correlation analyses between the bioactive endotoxins and 3-OHFAs with different carbon length were analyzed. Results showed that the correlations detected vary among sites and particulate sizes. Although no generalization between the total and bioactive endotoxins can be drawn from the study, the levels reported in this study suggests that the discrepancies between the two measurement approaches, and the bioactive potential of 3-OHFAs with individual carbon chains deserve further investigation.

Cheng, Jessica Y. W.; Hui, Esther L. C.; Lau, Arthur P. S.

2012-02-01

326

Local and regional effects of large scale atmospheric circulation patterns on winter wind power output in Western Europe  

NASA Astrophysics Data System (ADS)

Recent studies (Brayshaw, 2009, Garcia-Bustamante, 2010, Garcia-Bustamante, 2013) have drawn attention to the sensitivity of wind speed distributions and likely wind energy power output in Western Europe to changes in low-frequency, large scale atmospheric circulation patterns such as the North Atlantic Oscillation (NAO). Wind speed variations and directional shifts as a function of the NAO state can be larger or smaller depending on the North Atlantic region that is considered. Wind speeds in Ireland and the UK for example are approximately 20 % higher during NAO + phases, and up to 30 % lower during NAO - phases relative to the long-term (30 year) climatological means. By contrast, in southern Europe, wind speeds are 15 % lower than average during NAO + phases and 15 % higher than average during NAO - phases. Crucially however, some regions such as Brittany in N.W. France have been identified in which there is negligible variability in wind speeds as a function of the NAO phase, as observed in the ERA-Interim 0.5 degree gridded reanalysis database. However, the magnitude of these effects on wind conditions is temporally and spatially non-stationary. As described by Comas-Bru and McDermott (2013) for temperature and precipitation, such non-stationarity is caused by the influence of two other patterns, the East Atlantic pattern, (EA), and the Scandinavian pattern, (SCA), which modulate the position of the NAO dipole. This phenomenon has also implications for wind speeds and directions, which has been assessed using the ERA-Interim reanalysis dataset and the indices obtained from the PC analysis of sea level pressure over the Atlantic region. In order to study the implications for power production, the interaction of the NAO and the other teleconnection patterns with local topography was also analysed, as well as how these interactions ultimately translate into wind power output. The objective is to have a better defined relationship between wind speed and power output at a local level and a tool that wind farm developers could use to inform site selection. A particular priority was to assess how the potential wind power outputs over a 25-30 year windfarm lifetime in less windy, but resource-stable regions, compare with those from windier but more variable sites.

Zubiate, Laura; McDermott, Frank; Sweeney, Conor; O'Malley, Mark

2014-05-01

327

Atmospheric pollution in a semi-urban, coastal region in India following festival seasons  

NASA Astrophysics Data System (ADS)

The traditional Vishu festival in the state of Kerala in South India is celebrated in April with extensive coordinated fireworks display. The influence of these celebrations on the immediate and long-term air quality and impact on the health and well being of the public needs research. The combustion clouds contain harmful fumes (sulfur dioxide, oxides of nitrogen) and particulate matter released at the surface. This study is focused on the influence of fireworks on the air quality at Kannur, India, during Vishu in April 2010 and 2011. Elevated concentrations of various air pollutants such as O 3, NO 2, NO and PM 10 were measured during the intense usage of fireworks. Surprisingly, the organic analysis of the Particulate Matter (PM) samples collected on Vishu day revealed the emission of a variety of hazardous organic compounds during the fireworks display. One of the unique observations in this work is the nighttime production of O 3 by the photodissociation of NO 2 from the flash of firecrackers. The concentration of O 3 was observed to increase two fold over the control days of observation during the same month. Moreover, the concentrations of NO 2, and PM 10 increased by 100%. The concentration of NO was reduced by four fold during the event. A scheme based on the organic combustion from fireworks and peroxyl radical mediation is proposed for the nighttime production of ozone. The diurnal profile of all pollutants except NO showed higher concentrations starting from the Vishu eve on April 14 to Vishu day on April 15 and this pattern repeated for years 2010 and 2011. The fireworks activities have been increasing every year and generation of pollutants at their increased levels for short duration can potentially cause adverse health impacts on a regional scale in a highly populated region.

Nishanth, T.; Praseed, K. M.; Rathnakaran, K.; Satheesh Kumar, M. K.; Ravi Krishna, R.; Valsaraj, K. T.

2012-02-01

328

Recent surface mass balance from Syowa Station to Dome F, East Antarctica: comparison of field observations, atmospheric reanalyses, and a regional atmospheric climate model  

NASA Astrophysics Data System (ADS)

Stake measurements at 2 km intervals are used to determine the spatial and temporal surface mass balance (SMB) in recent decades along the Japanese Antarctic Research Expedition traverse route from Syowa Station to Dome F. To determine SMB variability at regional scales, this traverse route is divided into four regions, i.e., coastal, lower katabatic, upper katabatic and inland plateau. We also perform a regional evaluation of large scale SMB simulated by the regional atmospheric climate model versions 2.1 and 2.3 (RACMO2.1 and RACMO2.3), and the four more recent global reanalyses. Large-scale spatial variability in the multi-year averaged SMB reveals robust relationships with continentality and surface elevation. In the katabatic regions, SMB variability is also highly associated with surface slope, which in turn is affected by bedrock topography. Stake observation records show large inter-annual variability in SMB, but did not indicate any significant trends over both the last 40 years for the coastal and lower katabatic regions, and the last 20 years record for the upper katabatic and inland plateau regions. The four reanalyses and the regional climate model reproduce the macro-scale spatial pattern well for the multi-year averaged SMB, but fail to capture the mesoscale SMB increase at the distance interval ~300 to ~400 km from Syowa station. Thanks to the updated scheme in the cloud microphysics, RACMO2.3 shows the best spatial agreement with stake measurements over the inland plateau region. ERA-interim, JRA-55 and MERRA exhibit high agreement with the inter-annual variability of observed SMB in the coastal, upper katabatic and inland plateau regions, and moderate agreement in the lower katabatic region, while NCEP2 and RACMO2.1 inter-annual variability shows no significant correlation with the observations for the inland plateau region.

Wang, Yetang; Hou, Shugui; Sun, Weijun; Lenaerts, Jan T. M.; van den Broeke, Michiel R.; van Wessem, J. M.

2015-02-01

329

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

330

Atmospheric observations and emissions estimates of methane and nitrous oxide from regional to global scale  

NASA Astrophysics Data System (ADS)

Methane (CH4) and Nitrous Oxide (N2O) are the two most significant anthropogenic, long-lived, non-CO2 greenhouse gases, together perturbing the earth's energy balance by an amount comparable to that of CO2. This dissertation will focus on the use of atmospheric observations to quantify emissions of CH4 and N2O. First top-down emissions constraints on the regional scale, covering large areas of the U.S and southern Canada, are derived from airborne observations made in Spring of 2003. Using a receptor-oriented Lagrangian particle dispersion model provides robust validation of bottom-up emission estimates from EDGAR 32FT2000 and GEIA inventories. It is found that EDGAR CH4 emission rates are slightly low by a factor of 1.08 +/- 0.15 (2 sigma), while both EDGAR and GEIA N2O emissions are significantly too low, by factors of 2.62 +/- 0.50 and 3.05 +/- 0.61 respectively. This analysis is then extended over a full calendar year in 2004 with observations from NOAA's tall tower and aircraft profile network. EDGAR 32FT2000 CH 4 emissions are found to be consistent with observations, though the newer EDGAR v4.0 reduces CH4 emissions by 30%, and this reduction is not consistent with this study. Scaling factors found for N2O in May/June of 2003 (2.62 & 3.05) are found to hold for February-May of 2004, suggesting inventories are significantly too low in primary growing season coincident with significant fertilizer inputs. A new instrument for airborne observation of CO2, CH 4, N2O, and CO is introduced, and its operation and in-field performance are highlighted (demonstrated 1-sec precisions of 20 ppb, 0.5 ppb, 0.09 ppb, and 0.15 ppb respectively). Finally, global N2O observations collected with this sensor on the HIPPO (Hlaper Pole to Pole Observations) campaign are assessed. Comparison with a global model and subsequent inversion indicates strong, episodic inputs of nitrous oxide from tropical regions are necessary to bring observations and model in agreement. Findings highlight the strong temporal variability of nitrous oxide emissions, and the necessity of using full vertical profile observations in deriving emissions from atmospheric measurements.

Kort, Eric Adam

2011-12-01

331

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

NASA Astrophysics Data System (ADS)

Eddies 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

332

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

333

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

NASA Astrophysics Data System (ADS)

Understanding 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

334

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

335

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

336

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

337

Aerosol variability and atmospheric transport in the Himalayan region from CALIOP 2007-2010 observations  

NASA Astrophysics Data System (ADS)

This work quantifies the spatial distribution of different aerosol types, their seasonal variability and sources.The analysis of four years of CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) vertically resolved aerosol data allows the identification of spatial patterns of desert dust and carbonaceous particles in different atmospheric layers. Clusters of Lagrangian back trajectories highlight the transport pathways from source regions during the dusty spring season. The analysis shows a prevalence of dust; at low heights it occurs frequently (up to 70% of available observations) and is distributed north of the Tibetan Plateau with a main contribution from the Gobi and Taklamakan deserts, and west of the Tibetan Plateau, originating from the deserts of southwest Asia and advected by the Westerlies. Above the Himalayas the dust amount is minor but still not negligible (occurrence around 20%) and mainly affected by the transport from more distant deserts sources (Sahara and Arabian Peninsula). Carbonaceous aerosol, produced mainly in northern India and eastern China, is subject to shorter-range transport and is indeed observed closer to the sources, while there is a limited amount reaching the top of the plateau. Data analysis reveals a clear seasonal variability in the frequencies of occurrence for the main aerosol types; dust is regulated principally by the monsoon dynamics, with maximal occurrence in spring. We also highlight relevant interannual differences, showing a larger presence of aerosol in the region during 2007 and 2008. The characterization of the aerosol spatial and temporal distribution in terms of observational frequency is a key piece of information that can be directly used for the evaluation of global aerosol models.

Bucci, S.; Cagnazzo, C.; Cairo, F.; Di Liberto, L.; Fierli, F.

2014-05-01

338

Halocarbons in the atmosphere of the industrial-related Pearl River Delta region of China  

NASA Astrophysics Data System (ADS)

In a study conducted in 2000, 19 halocarbons from 78 canister air samples were measured in five industrial cities in the Pearl River Delta (PRD), one of the fastest growing industrial regions in China. Preliminary year 2000 halocarbon levels have been derived using available data and information. Comparisons have been made between the data obtained in this study and the corresponding estimated global/tropical surface mixing ratios obtained from the literature. With the exception of CFC-114 and halon-2402, the halocarbons had significant enhancements, presumably due to their recent increased production and extensive industrial uses. In contrast to the small enhancements (<7%) for two chlorofluorocarbons (CFC-11 and CFC-12), large enhancements (>30%) for three HCFC replacements (HCFC-22, -141b, -142b) were observed. In general, HCFCs have virtually replaced CFCs, except for some localized usage. The median of HFC-134a also had a 36% enhancement; however, 23% of the samples were near or at the global background level. These contradictory results could not give a clear situation of uses of this new chemical in the region. Our data also indicate that halocarbon-based cleaning solvents, including CFC-113, methyl chloroform, trichloroethene and tetrachloroethene, were still frequently used in PRD industries. High mixing ratios of these halogenated solvents were frequently measured in Dongguan, a city with light industry. Higher atmospheric levels of the three methyl halides (-Cl, -Br, and -I) were found in a coastal city, Jiangmen. These may be contributed to by industrial emissions and coastal terrestrial and coastal seawater sources.

Chan, L. Y.; Chu, K. W.

2007-02-01

339

Radiatively-Active Aerosols Within Mars' Atmosphere: Influences on the Weather and Climate as Simulated by the NASA ARC Mars GCM  

Microsoft Academic Search

Upgrades to the NASA Ames Research Center (ARC) Mars general circulation model (GCM) include a modernized radiative-transfer package which permits radiative effects and interactions of suspended atmospheric aerosols (e.g., water ice clouds, water vapor, dust, and their mutual interactions) to influence the net diabatic heating within the atmosphere. Atmospheric aerosols are critically important in determining the nature of the mean

J. Hollingsworth; M. A. Kahre; R. M. Haberle; F. Montmessin; R. Wilson; J. Schaeffer

2010-01-01

340

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

341

Strong influence of regional species pools on continent-wide structuring of local communities  

PubMed Central

There is a long tradition in ecology of evaluating the relative contribution of the regional species pool and local interactions on the structure of local communities. Similarly, a growing number of studies assess the phylogenetic structure of communities, relative to that in the regional species pool, to examine the interplay between broad-scale evolutionary and fine-scale ecological processes. Finally, a renewed interest in the influence of species source pools on communities has shown that the definition of the source pool influences interpretations of patterns of community structure. We use a continent-wide dataset of local ant communities and implement ecologically explicit source pool definitions to examine the relative importance of regional species pools and local interactions for shaping community structure. Then we assess which factors underlie systematic variation in the structure of communities along climatic gradients. We find that the average phylogenetic relatedness of species in ant communities decreases from tropical to temperate regions, but the strength of this relationship depends on the level of ecological realism in the definition of source pools. We conclude that the evolution of climatic niches influences the phylogenetic structure of regional source pools and that the influence of regional source pools on local community structure is strong. PMID:21676973

Lessard, Jean-Philippe; Borregaard, Michael K.; Fordyce, James A.; Rahbek, Carsten; Weiser, Michael D.; Dunn, Robert R.; Sanders, Nathan J.

2012-01-01

342

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

343

Characterization of atmospheric aerosol particles in a mountainous region in northern Japan  

NASA Astrophysics Data System (ADS)

In order to shed light on the long-range transport of atmospheric pollutants in the Northeast Asian Regions, we studied a multi-probe, chemical characterization and composition profile of airborne particulate matter (PM) on Mt. Moriyoshi (altitude 1454 m), located on the Sea of Japan side of northern Honshu, Japan. Sampling of size-resolved airborne PM was carried out on Juhyou-Daira (west side near the summit, altitude 1167 m) from February 1-16 (winter period) and July 7-19 (summer period) in 2004. Concentrations of several elemental and ionic species in each size-resolved PM sample were determined by particle-induced X-ray emission (PIXE) and ion chromatography analysis. From the winter period, results suggested that PM was formed from soil and sea salt particle sizes of PM 10-PM 2.5 and from ammonium sulfate particles, secondary particles < PM 1.0. However from the summer period, results suggested that PM was formed from soil and sea salt particles > PM 10-PM 2.5 and secondary particles < PM 1.0. With the aid of SEM-EDX analysis, many cubic particles were observed throughout the winter and summer periods. In particular, particles < PM 1.0 were almost all cubic particles. Small spherical particles were mainly detected in PM 10-PM 2.5 and PM 2.5-PM 1.0 categories of the winter period. These cubic and small spherical particles were the silicon-rich type.

Saitoh, K.; Sera, K.; Shirai, T.

2008-09-01

344

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

345

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

346

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

347

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

348

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

349

Regional Sea Level Changes Projected by the NASA/GISS Atmosphere-Ocean Model  

NASA Technical Reports Server (NTRS)

Sea level has been rising for the past century, and inhabitants of the Earth's coastal regions will want to understand and predict future sea level changes. In this study we present results from new simulations of the Goddard Institute for Space Studies (GISS) global atmosphere-ocean model from 1950 to 2099. Model results are compared with observed sea level changes during the past 40 years at 17 coastal stations around the world. Using observed levels of greenhouse gases between 1950 and 1990 and a compounded 0.5% annual increase in Co2 after 1990, model projections show that global sea level measured from 1950 will rise by 61 mm in the year 2000, by 212 mm in 2050, and by 408 mm in 2089. By 2089, two thirds of the global sea level rise will be due to thermal expansion and one third will be due to ocean mass changes. The spatial distribution of sea level rise is different than that projected by rigid lid ocean models.

Russell, Gary L.; Gornitz, Vivien; Miller, James R.

1999-01-01

350

Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 10611074 Seasonal variation of mesopause region wind shears,  

E-print Network

Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 1061­1074 Seasonal variation of mesopause region wind shears, convective and dynamic instabilities above Fort Collins, CO: A statistical) temperature and horizontal wind, observed by Colorado State University sodium lidar over Fort Collins, CO (411

2006-01-01

351

Spatial and seasonal variations of atmospheric organic carbon and elemental carbon in Pearl River Delta Region, China  

Microsoft Academic Search

The concentrations of organic carbon (OC) and elemental carbon (EC) in atmospheric particles were investigated at eight sites in four cities (Hong Kong, Guangzhou, Shenzhen and Zhuhai) of the Pearl River Delta Region (PRDR), China, during winter and summer 2002. The comparison of summer and winter results was made in order to investigate spatial and seasonal variations. PM2.5 and PM10

J. j. Cao; S. c. Lee; K. f. Ho; S. c. Zou; Kochy Fung; Y. Li; John G. Watson; Judith C. Chow

2004-01-01

352

Nighttime D region electron density measurements from ELF-VLF tweek radio atmospherics recorded at low latitudes  

E-print Network

. It plays an important role in the propagation of extremely low frequency (ELF: 30­3000Hz) and very lowNighttime D region electron density measurements from ELF- VLF tweek radio atmospherics recorded at low latitudes Ajeet K. Maurya,1 B. Veenadhari,2 Rajesh Singh,1 Sushil Kumar,3 M. B. Cohen,4 R

353

The effect of large anthropogenic particulate emissions on atmospheric aerosols, deposition and bioindicators in the eastern Gulf of Finland region  

Microsoft Academic Search

The effect of the emissions from large oil shale fuelled power plants and a cement factory in Estonia on the elemental concentration of atmospheric aerosols, deposition, elemental composition of mosses and ecological effects on mosses, lichens and pine trees in the eastern Gulf of Finland region has been studied. In addition to chemical analysis, fly ash, moss and aerosol samples

Liisa Jalkanen; Ahti Mäkinen; Erkki Häsänen; Jyrki Juhanoja

2000-01-01

354

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

355

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

356

Influence of climate change on the water resources in an alpine region.  

PubMed

It is widely accepted that the global warming will impact on water resources. This study investigates the possible influence of climate change on the water resources in an alpine region. A description of the actual situation with emphasis on the water resources from the one side and on the water consuming factors, here called stressors, is given. The probable effects of climate change in the region and their influence on its water resources are then described. The main outcome is that in the analysed region the climate change will rather have positive influence on the water balance by inducing higher precipitations during the rivers' natural low flow period (winter). This outcome contradicts many common predictions, however, this due to the specifics induced by the alpine nature of the catchment. PMID:18776619

De Toffol, S; Engelhard, C; Rauch, W

2008-01-01

357

Residual circulation and stratification in the Liverpool Bay region of freshwater influence  

Microsoft Academic Search

Wind and tidal straining are proposed as key mechanisms influencing the magnitude and timing of the horizontal flux of freshwater\\u000a across regions of freshwater influence (ROFIs). Evidence for this hypothesis is presented in estimates of the tidally averaged\\u000a residual current profile, obtained from 5 years of continuous acoustic doppler current profiler measurements in the Liverpool\\u000a Bay ROFI. The modified horizontal Richardson

Florence Verspecht; Tom P. Rippeth; John H. Simpson; Alejandro J. Souza; Hans Burchard; M. John Howarth

2009-01-01

358

Regional Precipitation Forecast with Atmospheric InfraRed Sounder (AIRS) Profile Assimilation  

NASA Technical Reports Server (NTRS)

Advanced technology in hyperspectral sensors such as the Atmospheric InfraRed Sounder (AIRS; Aumann et al. 2003) on NASA's polar orbiting Aqua satellite retrieve higher vertical resolution thermodynamic profiles than their predecessors due to increased spectral resolution. Although these capabilities do not replace the robust vertical resolution provided by radiosondes, they can serve as a complement to radiosondes in both space and time. These retrieved soundings can have a significant impact on weather forecasts if properly assimilated into prediction models. Several recent studies have evaluated the performance of specific operational weather forecast models when AIRS data are included in the assimilation process. LeMarshall et al. (2006) concluded that AIRS radiances significantly improved 500 hPa anomaly correlations in medium-range forecasts of the Global Forecast System (GFS) model. McCarty et al. (2009) demonstrated similar forecast improvement in 0-48 hour forecasts in an offline version of the operational North American Mesoscale (NAM) model when AIRS radiances were assimilated at the regional scale. Reale et al. (2008) showed improvements to Northern Hemisphere 500 hPa height anomaly correlations in NASA's Goddard Earth Observing System Model, Version 5 (GEOS-5) global system with the inclusion of partly cloudy AIRS temperature profiles. Singh et al. (2008) assimilated AIRS temperature and moisture profiles into a regional modeling system for a study of a heavy rainfall event during the summer monsoon season in Mumbai, India. This paper describes an approach to assimilate AIRS temperature and moisture profiles into a regional configuration of the Advanced Research Weather Research and Forecasting (WRF-ARW) model using its three-dimensional variational (3DVAR) assimilation system (WRF-Var; Barker et al. 2004). Section 2 describes the AIRS instrument and how the quality indicators are used to intelligently select the highest-quality data for assimilation. Section 3 presents an overall precipitation improvement with AIRS assimilation during a 37-day case study period, and Section 4 focuses on a single case study to further investigate the meteorological impact of AIRS profiles on synoptic scale models. Finally, Section 5 provides a summary of the paper.

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

2010-01-01

359

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

360

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

361

Three-year atmospheric monitoring of organochlorine pesticides and polychlorinated biphenyls in polar regions and the South Pacific.  

PubMed

XAD-2 resin based passive air samplers (PAS) were deployed for three one-year periods at the Korean polar and South Pacific research stations at Ny-Ålesund (2005-2009), King George Island (2005-2007), and Chuuk (2006-2009) to investigate long-range transport, local sources, and temporal trends of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The highest hexachlocyclohexane (HCH) concentration (35.2-78.9 pg·m(-3)) over the entire sampling period was detected at Ny-Ålesund, in the Arctic. ?-HCH was the dominant OCP (31.1-67.1 pg·m(-3)), contributing about 50% of the total OCP load. Additionally, a high and consistent ?/?-HCH ratio was observed at Ny-Ålesund. HCHs might reach Arctic sites more easily than other OCPs from surrounding countries through long-range atmospheric transport (LRAT). Interestingly, high levels of the current-use OCP endosulfan-particularly endosulfan-I--were detected at almost all sampling sites, including in Antarctica, ranging 12.2-88.5, 17.7-130, and ND-59.7 pg·m(-3) at King George Island, Ny-Ålesund, and Chuuk, respectively. Specific OCP and PCB patterns, such as low trans/cis-chlordane ratios and a prevalence of lighter PCB congeners, were observed in all three regions (excepting one site at Ny-Ålesund and one site in the South Pacific affected by local sources) during all sampling periods. This indicates that these Polar and remote South Pacific sites are mainly influenced by LRAT. Over the entire sampling period, a decreasing trend of HCHs (?- and ?-HCH) and an increasing trend of endosulfan-I were observed at the Ny-Ålesund sites. PMID:21488699

Baek, Song-Yee; Choi, Sung-Deuk; Chang, Yoon-Seok

2011-05-15

362

Influence of microphysical schemes on atmospheric water in the Weather Research and Forecasting model  

NASA Astrophysics Data System (ADS)

This study examines how different microphysical parameterization schemes influence orographically-induced precipitation and the distributions of hydrometeors and water vapour for mid-latitude summer conditions in the Weather Research and Forecasting (WRF) model. A high-resolution two-dimensional idealized simulation is used to assess the differences between the schemes in which a moist air flow is interacting with a bell-shaped 2 km high mountain. Periodic lateral boundary conditions are chosen to recirculate atmospheric water in the domain. It is found that the 13 selected microphysical schemes conserve the water in the model domain. The gain or loss of water is less than 0.81% over a simulation time interval of 61 days. The differences of the microphysical schemes in terms of the distributions of water vapour, hydrometeors and accumulated precipitation are presented and discussed. The Kessler scheme, the only scheme without ice-phase processes, shows final values of cloud liquid water 14 times greater than the other schemes. The differences among the other schemes are not as extreme, but still they differ up to 79% in water vapour, up to 10 times in hydrometeors and up to 64% in accumulated precipitation at the end of the simulation. The microphysical schemes also differ in the surface evaporation rate. The WRF single-moment 3-class scheme has the highest surface evaporation rate compensated by the highest precipitation rate. The different distributions of hydrometeors and water vapour of the microphysical schemes induce differences up to 49 W m-2 in the downwelling shortwave radiation and up to 33 W m-2 in the downwelling longwave radiation.

Cossu, F.; Hocke, K.

2013-09-01

363

Influence of microphysical schemes on atmospheric water in the Weather Research and Forecasting model  

NASA Astrophysics Data System (ADS)

This study examines how different microphysical parameterization schemes influence orographically induced precipitation and the distributions of hydrometeors and water vapour for midlatitude summer conditions in the Weather Research and Forecasting (WRF) model. A high-resolution two-dimensional idealized simulation is used to assess the differences between the schemes in which a moist air flow is interacting with a bell-shaped 2 km high mountain. Periodic lateral boundary conditions are chosen to recirculate atmospheric water in the domain. It is found that the 13 selected microphysical schemes conserve the water in the model domain. The gain or loss of water is less than 0.81% over a simulation time interval of 61 days. The differences of the microphysical schemes in terms of the distributions of water vapour, hydrometeors and accumulated precipitation are presented and discussed. The Kessler scheme, the only scheme without ice-phase processes, shows final values of cloud liquid water 14 times greater than the other schemes. The differences among the other schemes are not as extreme, but still they differ up to 79% in water vapour, up to 10 times in hydrometeors and up to 64% in accumulated precipitation at the end of the simulation. The microphysical schemes also differ in the surface evaporation rate. The WRF single-moment 3-class scheme has the highest surface evaporation rate compensated by the highest precipitation rate. The different distributions of hydrometeors and water vapour of the microphysical schemes induce differences up to 49 W m-2 in the downwelling shortwave radiation and up to 33 W m-2 in the downwelling longwave radiation.

Cossu, F.; Hocke, K.

2014-01-01

364

Sporadic E layer at mid-latitudes: average properties and influence of atmospheric tides  

NASA Astrophysics Data System (ADS)

This paper describes a study of the daily variability shown by the main 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 influenced by the atmospheric 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.

Pignalberi, A.; Pezzopane, M.; Zuccheretti, E.

2014-11-01

365

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

366

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

367

Atmospheric black carbon and warming effects influenced by the source and absorption enhancement in Central Europe  

NASA Astrophysics Data System (ADS)

Particles containing black carbon (BC), a strong absorbing substance, exert a rather uncertain direct and indirect radiative forcing in the atmosphere. To investigate the mass concentration and absorption properties of