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Sample records for influence regional atmospheric

  1. The influence of atmospheric circulation types on regional patterns of precipitation in Marmara (NW Turkey)

    NASA Astrophysics Data System (ADS)

    Baltac?, H.; K?ndap, T.; Ünal, A.; Karaca, M.

    2015-10-01

    In this study, regional patterns of precipitation in Marmara are described for the first time by means of Ward's hierarchical cluster analysis. Daily values of winter precipitation data based on 19 meteorological stations were used for the period from 1960 to 2012. Five clusters of coherent zones were determined, namely Black Sea-Marmara, Black Sea, Marmara, Thrace, and Aegean sub-regions. To investigate the prevailing atmospheric circulation types (CTs) that cause precipitation occurrence and intensity in these five different rainfall sub-basins, objective Lamb weather type (LWT) methodology was applied to National Centers of Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis of daily mean sea level pressure (MSLP) data. Precipitation occurrence suggested that wet CTs (i.e. N, NE, NW, and C) offer a high chance of precipitation in all sub-regions. For the eastern (western) part of the region, the high probability of rainfall occurrence is shown under the influence of E (SE, S, SW) atmospheric CTs. In terms of precipitation intensity, N and C CTs had the highest positive gradients in all the sub-basins of the Marmara. In addition, although Marmara and Black Sea sub-regions have the highest daily rainfall potential during NE types, high daily rainfall totals are recorded in all sub-regions except the Black Sea during NW types.

  2. Do regions outside the tropical Pacific influence ENSO through atmospheric teleconnections?

    NASA Astrophysics Data System (ADS)

    Dayan, H.; Izumo, T.; Vialard, J.; Lengaigne, M.; Masson, S.

    2015-08-01

    This paper aims at identifying oceanic regions outside the tropical Pacific, which may influence the El Niño Southern Oscillation (ENSO) through interannual modulation of equatorial Pacific winds. An Atmospheric General Circulation Model (AGCM) 7-members ensemble experiment forced by climatological sea surface temperature (hereafter, SST) in the tropical Pacific Ocean and observed interannually varying SST elsewhere produces ensemble-mean equatorial zonal wind stress interannual anomalies (ZWSA) over the equatorial Pacific. These ZWSA are largest during boreal winter in the western Pacific, and induce a ~0.5 °C response in the central Pacific during the following spring in a simple ocean model, that weakly but significantly correlates with the following ENSO peak amplitude. When correlated with global SST, the residual western equatorial Pacific ZWSA yield SST patterns that are reminiscent of ENSO teleconnections in the Indian, North and South Pacific, and Atlantic Oceans. We further design 20-members ensemble sensitivity experiments forced by typical SST patterns of the main climate modes for each of these regions, in order to identify regions that influence equatorial Pacific ZWSA most. In our experiments, only the Indian Ocean Basin-wide SST warming in late boreal winter produces a statistically significant ZWSA in the western equatorial Pacific, resulting in a weak but significant ~0.35 °C SST response in the central Pacific (i.e. ~35 % of the observed standard deviation) during the following spring, the season when the Bjerkness coupled feedback is particularly efficient. This paper hence agrees with previous studies, which suggest that ENSO-induced basin-wide SST signals in the Indian Ocean may contribute to the phase transition of ENSO. Our results suggest that studies exploring external influences on ENSO should adopt a global approach rather than focus on a specific region. Designing coupled model simulations would also allow investigating air-sea interactions-mediated teleconnection mechanisms, which we can't reproduce in our forced AGCM framework.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Atmospheric mercury data for the Coquimbo region, Chile: influence of mineral deposits and metal recovery practices

    NASA Astrophysics Data System (ADS)

    Higueras, Pablo; Oyarzun, Roberto; Lillo, Javier; Oyarzún, Jorge; Maturana, Hugo

    This work reports data of atmospheric mercury for northern Chile. The study was centered in the Coquimbo region, a realm rich in mineral deposits. Some of the mining districts have historic importance and have been exploited almost continuously since the Spanish colonial time (16-18th century). Two of these districts are particularly relevant: (1) Andacollo, initially exploited for gold, and then for copper and gold; and (2) Punitaqui, initially exploited for mercury, and then for copper and gold. The continuous mercury measurement procedures carried out during this survey, have proved to be an excellent tool to detect Hg signatures associated with the mining industrial activities. The combination of cumulative log-probability graphs and atmospheric mercury concentration profiles, allows clear differentiation between areas subjected to agriculture (2-3 ngHg m -3), from those in which mining and metal concentration activities take place (>10 ngHg m -3, most data well beyond this figure). Gold recovery involving milling and amalgamation appear as the most contaminant source of mercury, and yield concentrations in the order of 10 4-10 5 ngHg m -3 (Andacollo). Second in importance are the vein mercury deposits of Punitaqui, with concentrations above 100 ngHg m -3, whereas the flotation tailings of the district yield concentrations near to 100 ngHg m -3. The large and modern open pit operations of Andacollo (Carmen: Cu; Dayton: Au) do not show high concentrations of atmospheric mercury.

  5. Possible influence of atmospheric circulations on winter hazy pollution in Beijing-Tianjin-Hebei region, northern China

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Zhang, X.; Gong, D.; Kim, S.-J.; Mao, R.; Zhao, X.

    2015-08-01

    Using the daily records derived from the synoptic weather stations and the NCEP/NCAR and ERA-Interim reanalysis data, the variability of the winter hazy pollutions (indicated by the mean visibility and number of hazy days) in Beijing-Tianjin-Hebei (BTH) region during the period 1981 to 2015 and its relationship to the atmospheric circulations in middle-high latitude were analyzed in this study. The winter hazy pollution in BTH had distinct inter-annual and inter-decadal variabilities without a significant long-term trend. According to the spatial distribution of correlation coefficients, six atmospheric circulation indices (I1 to I6) were defined from the key areas in sea level pressure (SLP), zonal and meridional winds at 850 hPa (U850, V850), geopotential height field at 500 hPa (H500), zonal wind at 200 hPa (U200), and air temperature at 200 hPa (T200), respectively. All of the six indices have significant and stable correlations with the winter visibility and number of hazy days in BTH. Both the visibility and number of hazy days can be estimated well by using the six indices and fitting and the cross-validation with leave-N-out method, respectively. The high level of the prediction statistics and the reasonable mechanism suggested that the winter hazy pollutions in BTH can be forecasted or estimated credibly based on the optimized atmospheric circulation indices. However, we also noted that the statistic estimation models would be largely influenced by the artificial control of a pollutant discharge. Thus it is helpful for government decision-making departments to take actions in advance in dealing with probably severe hazy pollutions in BTH indicated by the atmospheric circulation conditions.

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

    SciTech Connect

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

    1991-08-01

    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.

  7. Relative Influence of Trans-Pacific and Regional Atmospheric Transport of PAHs in the Pacific Northwest, U.S.

    PubMed

    Lafontaine, Scott; Schrlau, Jill; Butler, Jack; Jia, Yuling; Harper, Barbara; Harris, Stuart; Bramer, Lisa M; Waters, Katrina M; Harding, Anna; Simonich, Staci L Massey

    2015-12-01

    The relative influences of trans-Pacific and regional atmospheric transport on measured concentrations of polycyclic aromatic hydrocarbons (PAHs), PAH derivatives (nitro- (NPAH) and oxy-(OPAH)), organic carbon (OC), and particulate matter (PM) less than 2.5 ?m in diameter (PM2.5) were investigated in the Pacific Northwest, U.S. in 2010-2011. Ambient high volume PM2.5 air samples were collected at two sites in the Pacific Northwest: (1.) Mount Bachelor Observatory (MBO) in the Oregon Cascade Range (2763 m above sea level (asl)) and 2.) Confederated Tribes of the Umatilla Indian Reservation (CTUIR) in the Columbia River Gorge (CRG) (954 m asl). At MBO, the 1,8-dinitropyrene concentration was significantly positively correlated with the time a sampled air mass spent over Asia, suggesting that this NPAH may be a good marker for trans-Pacific atmospheric transport. At CTUIR, NOx, CO2, and SO2 emissions from a 585 MW coal fired power plant, in Boardman OR, were found to be significantly positively correlated with PAH, OPAH, NPAH, OC, and PM2.5 concentrations. By comparing the Boardman Plant operational time frames when the plant was operating to when it was shut down, the plant was found to contribute a large percentage of the measured PAH (67%), NPAH (91%), OPAH (54%), PM2.5 (39%), and OC (38%) concentrations at CTUIR and the CRG prior to Spring 2011 and likely masked trans-Pacific atmospheric transport events to the CRG. Upgrades installed to the Boardman Plant in the spring of 2011 dramatically reduced the plant's contribution to PAH and OPAH concentrations (by ?72% and ?40%, respectively) at CTUIR and the CRG, but not NPAH, PM2.5 or OC concentrations. PMID:26151337

  8. The influence of regional-scale atmospheric circulations on chemical mixing over the western North Atlantic

    SciTech Connect

    Berkowitz, C.M.; Fast, J.D.

    1996-12-31

    The US East Coast urban corridor is a major source of pollutants, including ozone. Prevailing winds transport ozone eastward, eventually affecting air quality and increasing the background concentration of ozone over the western North Atlantic (WNA). Ozone also plays an important part in the initiation of many photochemical processes and as a greenhouse gas may have a role in possible climate change. Extensive measurements of ozone and other chemicals have been made recently over the WNA to determine the fate of ozone in the lower troposphere. Recent work has focused on the chemistry of ozone plumes over the WNA and the associated synoptic-scale meteorology. Large-scale circulation patterns also appear to play a role in producing elevated layers of high ozone mixing ratios. In general, ozone measurements off the coast of the WNA show that its distribution for both clean and polluted episodes is quite complex due to a combination of chemical process and transport features. In this work, the authors employ an atmospheric mesoscale model and a Lagrangian particle dispersion model to investigate the relationship between boundary-layer processes and mesoscale circulations and the airborne measurements of ozone taken over Yarmouth, Nova Scotia. The authors will present evidence of plume lofting and complex circulations and relate them to the chemical analysis presented by Kleinman et al.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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.

  10. Atmospheric composition - Influence of biology

    NASA Technical Reports Server (NTRS)

    Mcelroy, M. B.

    1983-01-01

    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.

  11. Modeling the influence of methane emissions from arctic gas hydrates on regional variations in composition of the lower atmosphere

    NASA Astrophysics Data System (ADS)

    Smyshlyaev, S. P.; Mareev, E. A.; Galin, V. Ya.; Blakitnaya, P. A.

    2015-07-01

    Numerical simulation with the use of the global chemistry-climate model of the lower and middle atmosphere has shown that the contribution of methane emissions from Arctic gas hydrates to the global production is most likely underestimated. An increase in methane emission as a result of Arctic warming may lead to a decrease in hydroxyl content and the formation of positive reverse correlation with CH4 content in emission area. The zones of variation in ozone content are distinct from those of the increase in CH4 content; the increase in ozone content with an increase in CH4 content is nonlinear and is retarded at high values of CH4 fluxes. This may be related to the decrease in hydroxyl content at an increase in CH4 emissions and reverse correlations, which compensate the additional ozone production.

  12. Influence of the Antarctic ozone hole on the polar mesopause region as simulated by the Canadian Middle Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Lossow, Stefan; McLandress, Charles; Jonsson, Andreas I.; Shepherd, Theodore G.

    2012-01-01

    It is well established that variations in polar stratospheric winds can affect mesospheric temperatures through changes in the filtering of gravity wave fluxes, which drive a residual circulation in the mesosphere. The Canadian Middle Atmosphere Model (CMAM) is used to examine this vertical coupling mechanism in the context of the mesospheric response to the Antarctic ozone hole. It is found that the response differs significantly between late spring and early summer, because of a changing balance between the competing effects of parametrised gravity wave drag (GWD) and changes in resolved wave drag local to the mesosphere. In late spring, the strengthened stratospheric westerlies arising from the ozone hole lead to reduced eastward GWD in the mesosphere and a warming of the polar mesosphere, just as in the well known mesospheric response to sudden stratospheric warmings, but with an opposite sign. In early summer, with easterly flow prevailing over most of the polar stratosphere, the strengthened easterly wind shear within the mesosphere arising from the westward GWD anomaly induces a positive resolved wave drag anomaly through baroclinic instability. The polar cooling induced by this process completely dominates the upper mesospheric response to the ozone hole in early summer. Consequences for the past and future evolution of noctilucent clouds are discussed.

  13. Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets

    SciTech Connect

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

    2007-03-07

    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.

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

    E-print Network

    Duck, Thomas J.

    Synoptic scale study of the Arctic polar vortex's influence on the middle atmosphere, 1-latitude middle atmosphere taken at three Arctic sites over similar time periods in midwinter. The four reported of the vortex is observed, it is noted that regional middle atmospheric Arctic temperatures can change by tens

  15. Influence of CO on Titan atmospheric reactivity

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The atmosphere of Titan is mainly composed of N2 and CH4, and photochemical volatiles products CxHyNz. Most of the laboratory studies simulating Titan's atmospheric reactivity focus on the highly complex carbon and nitrogen organic chemistry leading to a production of laboratory analogues of Titan's aerosols, called Tholins [Alcouffe et al., 2010]. However, the atmosphere of Titan also contains traces of oxygen compounds. The most abudant one detected is carbon monoxyde CO with a 47 ppmv concentration measured in high stratosphere [de Kok et al., 2007]. In this work we investigate the influence of CO on the N2-CH4 reactivity. We simulate the whole reaction chains with a laboratory Radio Frequency Capacitively Coupled plasma discharge (RF CCP) gas mixture of nitrogen, methane and carbon monoxyde. In order to detect unambiguously the possible effects, CO is introduced with amounts of 0 - 1 - 2.25 - 4.5 %, larger than in Titan's atmosphere. The kinetics of the methane is monitored by mass spectrometry and the compositions of the gas phase and tholins are monitored by GC-MS and elemental analysis respectively. We find that CO modifies the composition of the gas phase with the detection of oxygenated compounds. CO decreases drastically the production efficiency of tholins, involving also a perturbation on the methane kinetics. The oxygen incorporation in tholins is found to be efficient . As a conclusion, we show that carbon monoxyde is effectively coupled with N2-CH4 chemistry and that it impacts even the solid organic aerosols. References: Alcouffe, G., et al (2010), Capacitively coupled plasma used to simulate Titan's atmospheric chemistry, Plasma Sources Science and Technology, 19(1), 015008. de Kok, R., et al. (2007), Oxygen compounds in Titan's stratosphere as observed by Cassini CIRS, Icarus, 186(2), 354-363.

  16. Lunar influence on equatorial atmospheric angular momentum

    NASA Astrophysics Data System (ADS)

    Bizouard, Christian; Zotov, Leonid; Sidorenkov, Nikolay

    2014-11-01

    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.

  17. Tampa Bay Regional Atmospheric Chemistry Experiment: Overview

    NASA Astrophysics Data System (ADS)

    Atkeson, T. D.

    2003-12-01

    The Tampa Bay Estuary Program (TBEP) was formed in 1991 to assist in developing a comprehensive plan to restore and protect Tampa Bay in Florida, USA. An ecological indicator of the health of the Bay is the coverage of seagrasses, historically in decline, which are important to the aquatic habitat and food web of the bay. Seagrass decline is linked to excess of plant-stimulating forms of nitrogen to the bay, promoting algae growth, which shades out light needed to sustain seagrasses. One element of the TBEP is a private-local-state, multi-agency Nitrogen Management Consortium that seeks to limit nitrogen loading to the Bay to the 1992-1994 average. Present estimates suggest atmospheric deposition comprises ~ 30% of the nitrogen budget of the Bay. This estimate was based, however, on limited ambient monitoring data and simple models, typical of such national estuary program efforts nationwide. In the Bay Regional Atmospheric Chemistry Experiment Florida DEP joined with TBEP to increase the intensity, sophistication and spatial scope of monitoring and modeling and provide better information on air quality in the Tampa Bay area. The result will be improved estimates of the effects of local and regional emissions of oxides of nitrogen (NOx) on the Bay and the benefits to be gained from implementation of emissions reduction strategies.

  18. 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)

    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

    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.

  19. Energetic Particle Influence on the Earth's Atmosphere

    NASA Astrophysics Data System (ADS)

    Mironova, Irina A.; Aplin, Karen L.; Arnold, Frank; Bazilevskaya, Galina A.; Harrison, R. Giles; Krivolutsky, Alexei A.; Nicoll, Keri A.; Rozanov, Eugene V.; Turunen, Esa; Usoskin, Ilya G.

    2015-11-01

    This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth's atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere.

  20. Energetic Particle Influence on the Earth's Atmosphere

    NASA Astrophysics Data System (ADS)

    Mironova, Irina A.; Aplin, Karen L.; Arnold, Frank; Bazilevskaya, Galina A.; Harrison, R. Giles; Krivolutsky, Alexei A.; Nicoll, Keri A.; Rozanov, Eugene V.; Turunen, Esa; Usoskin, Ilya G.

    2015-09-01

    This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth's atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere.

  1. INTRODUCTION Atmospheric aerosol particles influence the Earth's

    E-print Network

    Wunderle, Stefan

    - ability means a complex and challenging task in today's atmosphere and climate related science. During to enhance the frequency of aerosol mapping due to their high repetition rate. The objective of this study

  2. 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...

  3. 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 ...

  4. REGIONAL-SCALE ATMOSPHERIC MERCURY MODELING

    EPA Science Inventory

    This PowerPoint presentation gives a short synopsis of the state of the science of atmospheric mercury modeling, including a description of recent publications of model codes by EPA, a description of a recent mercury model intercomparison study, and a description of a synthesis p...

  5. Influence of the African Great Lakes on the regional climate

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Davin, Edouard; Panitz, Hans-Jürgen; Demuzere, Matthias; Lhermitte, Stef; van Lipzig, Nicole

    2015-04-01

    Although the African Great Lakes are important regulators for the East-African climate, their influence on atmospheric dynamics and the regional hydrological cycle remains poorly understood. We aim to assess this impact by conducting a regional climate model simulation which resolves individual lakes and explicitly computes lake temperatures. The regional climate model COSMO-CLM, coupled to a state-of-the-art lake parameterization scheme and land surface model, is used to dynamically downscale the COSMO-CLM CORDEX-Africa evaluation simulation to 7 km grid spacing for the period 1999-2008. Evaluation of the model reveals good performance compared to both in-situ and satellite observations, especially for spatio-temporal variability of lake surface temperatures and precipitation. Model integrations indicate that the four major African Great Lakes almost double precipitation amounts over their surface relative to a simulation without lakes, but hardly exert any influence on precipitation beyond their shores. The largest lakes also cool their near-surface air, this time with pronounced downwind influence. The lake-induced cooling happens during daytime, when the lakes absorb incoming solar radiation and inhibit upward turbulent heat transport. At night, when this heat is released, the lakes warm the near-surface air. Furthermore, Lake Victoria has profound influence on atmospheric dynamics and stability as it induces cellular motion with over-lake convective inhibition during daytime, and the reversed pattern at night. Overall, this study shows the added value of resolving individual lakes and realistically representing lake surface temperatures for climate studies in this region. Thiery, W., Davin, E., Panitz, H.-J., Demuzere, M., Lhermitte, S., van Lipzig, N.P.M., The impact of the African Great Lakes on the regional climate, J. Climate (in review).

  6. Sensitivity of Air-sea Exchange In A Regional Scale Coupled Ice/ocean/atmosphere Model

    NASA Astrophysics Data System (ADS)

    Schrum, C.; Hübner, U.; Jacob, D.; Podzun, R.

    The sub-systems ice, ocean and atmosphere are coupled on the global as well as the regional scale. However, regional coupled modeling is only in the beginning, full cou- pled models which are able to describe the interaction on the regional scale and the feedback mechanism are rare at the moment. For the North Sea and the Baltic Sea such a coupled model has been developed and exemplary integrated over a full seasonal cy- cle. By comparison of different regionalization studies the impact of the regional at- mospheric modeling and coupling on the air sea fluxes have been investigated. It was shown that the regionalization as well as the coupling show strong influence on the air/sea fluxes and thus on the oceanic conditions. Further problems in regional mod- eling like the description of storm track variability and its influence on the regional ocean model were identified.

  7. Pesticides in the Atmosphere: Current Understanding of Distribution and Major Influences

    USGS Publications Warehouse

    U.S. Geological Survey

    1995-01-01

    This report summarizes a comprehensive analysis of existing information on national and regional patterns of pesticides in the atmosphere and major influences on their sources and transport. It is one of a four-part series that synthesizes current knowledge and understanding of pesticides in water resources of the nation as part of the National Water-Quality Assessment.

  8. Lunar influence on equatorial atmospheric angular momentum

    NASA Astrophysics Data System (ADS)

    Bizouard, C.; Zotov, L.; Sidorenkov, N.

    2015-08-01

    This study investigates the relationship between the equatorial atmospheric angular momentum oscillation in the non-rotating frame and lunar tidal potential. Between 2 and 30 days, the corresponding equatorial component is mostly constituted of prograde circular motions, especially of a harmonic at 13.6 days, and of a weekly broad band variation. A simple equilibrium tide model explains the 13.6-day pressure term as result of the O1 lunar tide; the tidal lunar origin of the whole band from 2 to 30 days is attested by specific features, not occurring for seasonal band dominated by the solar thermal effect.

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

    E-print Network

    Boyd, Robert W.

    Influence of atmospheric turbulence on states of light carrying orbital angular momentum Brandon carrying orbital angular momentum (OAM) propagating through simulated atmospheric turbulence channel is the effect that atmospheric turbulence has on the crosstalk between channels. Atmospheric

  10. Spatial extent of the North American Monsoon: Increased cross-regional linkages via atmospheric pathways

    E-print Network

    Spatial extent of the North American Monsoon: Increased cross- regional linkages via atmospheric extent of the North American Monsoon: Increased cross-regional linkages via atmospheric pathways, Geophys

  11. Regional climatic effects of atmospheric SO2 on Mars

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  12. Identifying human influences on atmospheric temperature

    PubMed Central

    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

    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

  13. Identifying human influences on atmospheric temperature.

    PubMed

    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

    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

  14. Fire Influences on Atmospheric Composition, Air Quality, and Climate

    NASA Technical Reports Server (NTRS)

    Voulgarakis, Apostolos; Field, Robert D.

    2015-01-01

    Fires impact atmospheric composition through their emissions, which range from long-lived gases to short-lived gases and aerosols. Effects are typically larger in the tropics and boreal regions but can also be substantial in highly populated areas in the northern mid-latitudes. In all regions, fire can impact air quality and health. Similarly, its effect on large-scale atmospheric processes, including regional and global atmospheric chemistry and climate forcing, can be substantial, but this remains largely unexplored. The impacts are primarily realised in the boundary layer and lower free troposphere but can also be noticeable in upper troposphere/lower stratosphere (UT/LS) region, for the most intense fires. In this review, we summarise the recent literature on findings related to fire impact on atmospheric composition, air quality and climate. We explore both observational and modelling approaches and present information on key regions and on the globe as a whole. We also discuss the current and future directions in this area of research, focusing on the major advances in emission estimates, the emerging efforts to include fire as a component in Earth system modelling and the use of modelling to assess health impacts of fire emissions.

  15. 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...

  16. The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation

    SciTech Connect

    Yang, R.

    1992-01-01

    The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation is studied through the use of the Simple Biosphere Model (SiB) and the Center for Ocean-Land-Atmosphere interactions (COLA) GCM. Tests for the SiB sensitivity to the conversion of the forest to other short vegetation or bare soil were performed at Amazonian and Great Plains sites, and a North Wales spruce forest site respectively. The results show that deforestation has a significant influence on the local surface energy budget and surface weather. The influence is especially prominent at the Amazon and Great Plains sites, and larger in summer than in other seasons. The influence on the partitioning of surface incoming radiative energy is generally constrained by the local atmospheric boundary condition. The sensitivity of the COLA GCM to changes in initial soil wetness (ISW) is determined by repeating three 10-day model integrations with the same initial and boundary conditions as the control runs except the values of ISW, which are revised at 69 model grid points covering much of the continental U.S. It is found that the relations between the changes in the 5-day mean forecast surface air temperature/surface specific humidity and the changes in ISW depend upon vegetation type and the values of ISW, and can be approximated by regression equations. These relations are also confirmed with independent data. With the ISW revised based on these regression equations the surface forecasts of the revised runs are consistently improved. The spatial scale of the ISW anomaly determines the degree and range of the influence. The influence of a small regional ISW change is mainly confined to the local region and to low atmospheric levels. The influence on surface fluxes is strong and persists for more than one month, but the effects on precipitation are relatively weak, changeable, and complex, particularly when an interactive cloud scheme is used.

  17. Influence of Dust Loading on Atmospheric Ionizing Radiation on Mars

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  18. Influence of dust loading on atmospheric ionizing radiation on Mars

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  19. Surface roughness variations control the regional atmospheric response to contemporary scale deforestation in Rondônia, Brazil

    NASA Astrophysics Data System (ADS)

    Khanna, Jaya; Medvigy, David

    2015-04-01

    The atmospheric response to deforestation is closely tied to the scale of the land cover change. In the Amazon, deforestation at small scale (˜1 km) has been observed to give rise to an increase in cloudiness and rain, triggered by horizontal thermal variations between forest and bare land. Large scale (hundreds of kms) Amazonian deforestation, on the other hand, has been predicted to cause warming and drying. Noticeably, our knowledge of the net atmospheric response to intermediate scale (tens of kms) deforestation in the Amazon is incomplete and so the scale dependence of the regional atmospheric response is not well understood. This mesoresolution case study of contemporary deforestation in Rondônia, Brazil aims at investigating the coupled dynamical and thermodynamical regional atmospheric response to intermediate scale deforestation. Our numerical simulations, conducted using the variable resolution Ocean-Land-Atmosphere-Model, show that the regional atmospheric response to intermediate scales of deforestation is dominated by surface roughness variations between forests and clearings. These variations trigger a mesoscale circulation which makes the atmosphere conducive to convection in the downwind side and suppresses convection in the upwind side of the deforested domain. Unlike the thermally generated mesoscale circulations, which occur only during the dry season, this dynamically generated circulation is present year round. Moreover, the atmospheric response is found to be strongest during the wet season marked by an ˜8% increase (compared to the control case) in the relative humidity in and around the upwelling branch of the circulation. Overall the study shows that the atmospheric response to contemporary intermediate scale deforestation in Rondônia is likely to be more influenced by differences in surface roughness between forest and forest clearings than by the differences in the surface energy partitioning.

  20. Atmospheric Environment 40 (2006) 17431758 Impact of urban heat island on regional atmospheric pollution

    E-print Network

    2006-01-01

    , it becomes a priority to understand the strong interactions between urban micrometeorology and air pollution pollution C. Sarrata,Ã, A. Lemonsub , V. Massona , D. Guedaliac a CNRM-GAME Me´te´o-France 42, avenue and spatial distribution of atmospheric pollutants over the Paris region. One anticyclonic episode from

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    What fraction of the black carbon arriving on Yala Glacier in Langtang, Nepal, is from cooking fires in the houses in the valley below? What fraction is from elsewhere in rural Nepal? What fraction is from industrial and transport sources in Kathmandu? What fraction is from northern India and beyond? What fraction is from the high altitude forest fires that take place during March or April? Effectively mitigating the impacts of black carbon and other short-lived climate forcers requires detailed understanding not just of emissions and impacts, but also of the atmospheric transport pathways that connect the two. In mountainous areas of the Hindu-Kush Himalaya detailed quantitative knowledge about emissions, atmospheric processes, and impacts is still largely missing. The International Centre for Integrated Mountain Development (ICIMOD) is an intergovernmental organization covering Afghanistan, Pakistan, India, Nepal, China, Bhutan, Bangladesh, and Myanmar. ICIMOD's recently established Atmosphere Initiative not only assesses mitigation options and contributes to policy and capacity building in the region, but also works actively to promote collaboration among researchers in the region, while building up an in-house team whose research will address key questions about SLCF. In Spring 2013 ICIMOD's Atmosphere Initiative, in collaboration with the Institute for Advanced Sustainability Studies (IASS) in Potsdam, Germany, carried out the largest field campaign to date in Nepal, hosting instruments belonging to dozens of institutions around the world, at nine field site within and upwind of the Kathmandu Valley, Nepal. The dataset that has been collected gives unprecedented insights into the emissions and atmospheric processes taking place downwind of and within the largest urban agglomeration in the Himalaya region. Meanwhile, in collaboration with national partner institutions, ICIMOD is in the process of setting up one atmospheric observatory each in Bhutan and in Nepal. Each will be on a mountain peak overlooking the Indo-Gangetic Plains. A building will house laboratories and visitor space, and will have a small tower. Each site will be equipped with a Picarro G2401 analyzer for CO, CO¬2, methane and water vapor, aerosol filter samplers, as well as instruments to measure black carbon, ozone, aerosol size distribution, aerosol scattering, cloud condensation nuclei, solar radiation, aerosol optical depth, and meteorology. Together with output from ICIMOD's new atmospheric modeling centre, the data from the sites will allow quantifying the flux of pollutants from the Indo-Gangetic Plains towards the high Himalaya, and to estimate emissions of SLCFs within the Himalayan foothills region. The infrastructure at both observatory sites is designed to accommodate training and future expansion as well as to host visiting instruments.

  2. Relative Influence of Initial Surface and Atmospheric Conditions on Seasonal Water and Energy Balances

    NASA Technical Reports Server (NTRS)

    Oglesby, Robert J.; Marshall, Susan; Roads, John O.; Robertson, Franklin R.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    We constructed and analyzed wet and dry soil moisture composites for the mid-latitude GCIP region of the central US using long climate model simulations made with the NCAR CCM3 and reanalysis products from NCEP. Using the diagnostic composites as a guide, we have completed a series of predictability experiments in which we imposed soil water initial conditions in CCM3 for the GCIP region for June 1 from anomalously wet and dry years, with atmospheric initial conditions taken from June 1 of a year with 'near-normal' soil water, and initial soil water from the near-normal year and atmospheric initial conditions from the wet and dry years. Preliminary results indicate that the initial state of the atmosphere is more important than the initial state of soil water determining the subsequent late spring and summer evolution of sod water over the GCIP region. Surprisingly, neither the composites or the predictability experiments yielded a strong influence of soil moisture on the atmosphere. To explore this further, we have made runs with extreme dry soil moisture initial anomalies imposed over the GCIP region (the soil close to being completely dry). These runs did yield a very strong effect on the atmosphere that persisted for at least three months. We conclude that the magnitude of the initial soil moisture anomaly is crucial, at least in CCM3, and are currently investigating whether a threshold exists, below which little impact is seen. In a complementary study, we compared the impact of the initial condition of snow cover versus the initial atmospheric state over the western US (corresponding to the westward extension of the GAPP program follow-on to GCIP). In this case, the initial prescription of snow cover is far more important than the initial atmospheric state in determining the subsequent evolution of snow cover. We are currently working to understand the very different soil water and snow cover results.

  3. Atmospheric responses to oceanic eddies in the Kuroshio Extension region

    NASA Astrophysics Data System (ADS)

    Ma, Jing; Xu, Haiming; Dong, Changming; Lin, Pengfei; Liu, Yu

    2015-07-01

    We examined atmospheric responses to 35,000+ oceanic eddies in the Kuroshio Extension region during the period of 2006-2009. Using satellite data, we showed that cold (warm) eddies cause surface winds to decelerate (accelerate) and reduce (increase) latent and sensible heat fluxes, cloud liquid water, water vapor content, and rain rate; all of these changes are quantified. Both the linear correlation between wind divergence and downwind sea surface temperature (SST) gradient and the correspondence between vorticity and crosswind SST gradient support the vertical momentum mixing mechanism, which indicates that SST perturbations modify surface winds by changing the vertical turbulent mixing in the marine atmospheric boundary layer (MABL). High-resolution National Centers for Environmental Prediction Climate Forecast System Reanalysis (CFSR) data can reproduce the atmospheric responses to the oceanic eddies in the MABL albeit with some differences in intensity. In addition, the CFSR data reveal that the atmospheric responses to these oceanic eddies are not confined in the MABL. MABL deepens (shoals) over the warm (cold) eddies; enhanced (reduced) vertical transport of transient zonal momentum occurs over the warm (cold) eddies from the sea surface to about 850 hPa level; vertical velocity anomalies over oceanic eddies penetrate beyond the MABL into free atmosphere; there exists a positive correlated relationship between SST and convective rain rate anomalies, indicative of ocean eddies' impact on the free troposphere. However, the composites of cloud liquid water and rain rate are different from the results based on the satellite data.

  4. Collective Processes in the Transition Region of the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Bespalov, P. A.; Savina, O. N.

    Special features of the ion-acoustic oscillation instability in the transition region of a quiet solar atmosphere are examined. A model of electron distribution function, which corresponds to the heat flux, under condition of absence of a particular beam, is analyzed. It is shown that the heat flux-related anisotropy of the distribution function is sufficient for the achievement of the threshold of ion-acoustic instability in the transition region. A characteristic value of the electric field in ion-acoustic turbulence is estimated.

  5. Automated Detection of Oscillating Regions in the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Ireland, J.; Marsh, M. S.; Kucera, T. A.; Young, C. A.

    2010-01-01

    Recently observed oscillations in the solar atmosphere have been interpreted and modeled as magnetohydrodynamic wave modes. This has allowed for the estimation of parameters that are otherwise hard to derive, such as the coronal magnetic-field strength. This work crucially relies on the initial detection of the oscillations, which is commonly done manually. The volume of Solar Dynamics Observatory (SDO) data will make manual detection inefficient for detecting all of the oscillating regions. An algorithm is presented that automates the detection of areas of the solar atmosphere that support spatially extended oscillations. The algorithm identifies areas in the solar atmosphere whose oscillation content is described by a single, dominant oscillation within a user-defined frequency range. The method is based on Bayesian spectral analysis of time series and image filtering. A Bayesian approach sidesteps the need for an a-priori noise estimate to calculate rejection criteria for the observed signal, and it also provides estimates of oscillation frequency, amplitude, and noise, and the error in all of these quantities, in a self-consistent way. The algorithm also introduces the notion of quality measures to those regions for which a positive detection is claimed, allowing for simple post-detection discrimination by the user. The algorithm is demonstrated on two Transition Region and Coronal Explorer (TRACE) datasets, and comments regarding its suitability for oscillation detection in SDO are made.

  6. Polychlorinated biphenyls and organochlorine pesticides in atmospheric air of the Northern Hovsgol region in 2008-2013

    NASA Astrophysics Data System (ADS)

    Mamontova, E. A.; Tarasova, E. N.; Goreglyad, A. V.; Tkachenko, L. L.; Mamontov, A. A.; Kuzmin, M. I.

    2015-10-01

    Results of the study of organochlorine pesticides (OCP) and polychlorinated biphenyls (PCB) from the listing of the Stockholm Convention in atmospheric air of the Northern Hovsgol region at the base of the "Khankh" stationary, Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences, in 2008-2013 in the absence of clear sources of these compounds are considered. Quantitative and qualitative changes in the concentration of PCB and OCP in atmospheric air of the Northern Hovsgol region in 2008-2013 characterizing the influence of natural (annual temperature variations) and anthropogenic (atmospheric transportation from the territories of neighboring countries) are shown.

  7. The Influence of COSMIC Satellite Data on Regional Analysis

    NASA Astrophysics Data System (ADS)

    Kuo, Y.

    2006-12-01

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

  8. Atmosphere Dynamics of the Active Region NOAA 11024

    NASA Astrophysics Data System (ADS)

    Kondrashova, N. N.; Pasechnik, M. N.; Chornogor, S. N.; Khomenko, E. V.

    2013-06-01

    We present results of the study of chromospheric and photospheric line-of-sight velocity fields in the young active region NOAA 11024. Multi-layer, multi-wavelength observational data were used for the analysis of the emerging flux in this active region. Spectropolarimetric observations were carried out with the telescope THEMIS on Tenerife (Canary Islands) on 4 July 2009. In addition, space-borne data from SOHO/MDI, STEREO and GOES were also considered. The combination of data from ground- and space-based telescopes allowed us to study the dynamics of the lower atmosphere of the active region with high spatial, spectral, and temporal resolutions. THEMIS spectra show strong temporal variations of the velocity in the chromosphere and photosphere for various activity features: two pores, active and quiet plage regions, and two surges. The range of variations of the chromospheric line-of-sight velocity at the heights of the formation of the H? core was extremely large. Both upward and downward motions were observed in these layers. In particular, a surge with upward velocities up to -73 km s-1 was detected. In the photosphere, predominantly upward motions were found, varying from -3.1 km s-1 upflows to 1.4 km s-1 downflows in different structures. The velocity variations at different levels in the lower atmosphere are compatible with the emergence of magnetic flux.

  9. NAO influence on net sea ice production and exchanges in the Arctic region

    E-print Network

    Hu, Aixue

    the Arctic and its adjacent seas will change the surface buoyancy forcing in the latter, thus impactingNAO influence on net sea ice production and exchanges in the Arctic region Aixue Hu National Center Submitted to Journal of Climate Corresponding author: Aixue Hu, National Center for Atmospheric Research, PO

  10. Critical review of studies on atmospheric dispersion in coastal regions

    SciTech Connect

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

    1982-09-01

    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.

  11. Influence of the Laurentian Great Lakes on Regional Climate

    NASA Astrophysics Data System (ADS)

    Notaro, M.; Holman, K.; Zarrin, A.; Fluck, E.; Vavrus, S. J.; Bennington, V.

    2012-12-01

    The influence of the Laurentian Great Lakes on climate is assessed by comparing two decade-long simulations, with the lakes either included or excluded, using the Abdus Salam International Centre for Theoretical Physics Regional Climate Model Version 4. The Great Lakes dampen the variability in near-surface air temperature across the surrounding region, while reducing the amplitude of the diurnal cycle and annual cycle of air temperature. The impacts of the Great Lakes on the regional surface energy budget include an increase (decrease) in turbulent fluxes during the cold (warm) season and an increase in surface downward shortwave radiation flux during summer due to diminished atmospheric moisture and convective cloud amount. Changes in the hydrologic budget due to the presence of the Great Lakes include increases in evaporation and precipitation during October-March and decreases during May-August, along with springtime reductions in snowmelt-related runoff. Circulation responses consist of a regionwide decrease in sea-level pressure in autumn-winter and an increase in summer, with enhanced ascent and descent in the two seasons, respectively. The most pronounced simulated impact of the Great Lakes on synoptic systems traversing the basin is a weakening of cold-season anticyclones.

  12. Magma ocean influence on early atmosphere mass and composition

    NASA Astrophysics Data System (ADS)

    Hirschmann, Marc M.

    2012-08-01

    Redox conditions in magma oceans (MOs) have a key influence on the mass and composition of Earth's early atmosphere. If the shallow part of the MO is oxidized, it may be overlain by an H2O-CO2 atmosphere, but if the near-surface magma is close to equilibrium with Fe-rich alloy, then the atmosphere will consist chiefly of H2, H2O, and CO, and on cooling will be rich in CH4. Although MOs are intimately associated with core-forming metal, the redox conditions in their shallow parts are not necessarily reducing. The magmatic Fe3+/FeT ratio is set by equilibrium with metal at depth and homogenized through the magma column by convection. Indirect evidence suggests that the Fe3+/FeT ratio of magmas in equilibrium with alloy at high pressure is greater than at low pressure, such that the shallow part of the MO may be comparatively oxidized and coexist with an atmosphere consisting chiefly of H2O and CO2. The mass of the atmosphere is dictated by the concentrations of volatile-species dissolved in the magma, which in turn are determined by partitioning between magma and alloy. Very strong partitioning of C into alloy may capture most of the carbon delivered to the growing planet, leaving behind a C-poor bulk silicate Earth (BSE) and a C-poor atmosphere. However, modest solubility of CH4 in the magma may allow the BSE to retain significant C. Alternatively, if partitioning of C into alloy is extreme but the fraction of metal equilibrated with the MO is small, the alloy may become saturated with diamond. Floatation of diamond in the MO may retain a substantial inventory of C in the early mantle. BSE C may also have been replenished in a late veneer. Following segregation of metal to the core, crystallization of the MO may have prompted precipitation of C-rich phases (graphite, diamond, carbide), limiting the C in the early atmosphere and creating a substantial interior C inventory that may account for the large fraction of BSE carbon in the mantle today. Such precipitation could have occurred owing to a combination of the redox evolution of the crystallizing MO and cooling.

  13. The Regional Environmental Impacts of Atmospheric Aerosols over Egypt

    NASA Astrophysics Data System (ADS)

    Zakey, Ashraf; Ibrahim, Alaa

    2015-04-01

    Identifying the origin (natural versus anthropogenic) and the dynamics of aerosols over Egypt at varying temporal and spatial scales provide valuable knowledge on the regional climate impacts of aerosols and their ultimate connections to the Earth's regional climate system at the MENA region. At regional scale, Egypt is exposed to air pollution with levels exceeding typical air-quality standards. This is particularly true for the Nile Delta region, being at the crossroads of different aerosol species originating from local urban-industrial and biomass-burning activities, regional dust sources, and European pollution from the north. The Environmental Climate Model (EnvClimA) is used to investigate both of the biogenic and anthropogenic aerosols over Egypt. The dominant natural aerosols over Egypt are due to the sand and dust storms, which frequently occur during the transitional seasons (spring and autumn). In winter, the maximum frequency reaches 2 to 3 per day in the north, which decreases gradually southward with a frequency of 0.5-1 per day. Monitoring one of the most basic aerosol parameters, the aerosol optical depth (AOD), is a main experimental and modeling task in aerosol studies. We used the aerosol optical depth to quantify the amount and variability of aerosol loading in the atmospheric column over a certain areas. The aerosols optical depth from the model is higher in spring season due to the impacts of dust activity over Egypt as results of the westerly wind, which carries more dust particles from the Libyan Desert. The model result shows that the mass load of fine aerosols has a longer life-time than the coarse aerosols. In autumn season, the modelled aerosol optical depth tends to increase due to the biomass burning in the delta of Egypt. Natural aerosol from the model tends to scatter the solar radiation while most of the anthropogenic aerosols tend to absorb the longwave solar radiation. The overall results indicate that the AOD is lowest in winter due to airborne particles washed out by rain events. Conversely, the AOD increases in summer because particle accumulation is favored by the absence of precipitation during this season. Moreover, in summer, photochemical processes in the atmosphere lead to slight increases in the values of aerosol optical characteristics, despite lower wind speeds [hence less wind-blown dust] relative to other seasons. This study has been conducted under the PEER 2-239 research project titled "the Impact of Biogenic and Anthropogenic Atmospheric Aerosols to Climate in Egypt". Project website: CleanAirEgypt.org

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

    E-print Network

    Jackman, Charles H.

    Neutral atmospheric influences of the solar proton events in October--November 2003 Charles H the substantial impact of solar protons on the polar neutral middle atmosphere. Citation: Jackman, C. H., M. T. De), Neutral atmospheric influences of the solar proton events in October­November 2003, J. Geophys. Res., 110

  15. Influence of atmospheric turbulence on the propagation of quantum states of light carrying

    E-print Network

    Boyd, Robert W.

    Influence of atmospheric turbulence on the propagation of quantum states of light carrying orbital We analyze the influence of atmospheric turbulence on the propagation of an optical vortex beam the atmosphere has the same value of the orbital angular momentum as the launched photon is found to be given

  16. Modulation mechanisms of marine atmospheric boundary layer at the Brazil-Malvinas Confluence region

    NASA Astrophysics Data System (ADS)

    Camargo, Ricardo; Todesco, Enzo; Pezzi, Luciano Ponzi; Souza, Ronald Buss

    2013-06-01

    The influence of the Brazil-Malvinas Confluence (BMC) region on the marine atmospheric boundary layer (MABL) is investigated through in situ data analysis of five different cruises (2004 to 2008) and numerical experiments with a regional atmospheric model. Two different groups of numerical experiments were performed in order to evaluate the relevance of static stability and hydrostatic balance physical mechanisms for the MABL instability. The first group used monthly climatological sea surface temperature (SST) as bottom boundary condition while the second used daily updated Advanced Microwave Scanning Radiometer-EOS SST data together with radiosondes and surface data assimilation. A reasonable agreement between numerical results and QuikSCAT wind data was observed through correlation coefficients and mean square error values. In terms of the horizontal structure of the MABL, stronger winds were found over the warm side of the BMC region as well as over the thermal front itself, which supports the coexistence of both modulation mechanisms. The analyzed patterns of surface atmospheric thermal advection showed a clear interaction between the synoptic and regional scales. The signature of the oceanic thermal front (almost meridionally oriented) on the air temperature at 2 m makes the temperature advection strongly determined by the zonal component of the wind. The analysis of momentum budget terms did not show a clear and reasonable explanation of the existence or predominance of the modulation mechanisms, and it also suggested the relevance of other effects, such as the idea based on unbalanced Coriolis force and turbulence/friction effects.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  18. Influence of Atmospheric Pressure and Composition on LIBS

    SciTech Connect

    Jeremy J. Hatch; Jill R. Scott; Effenberger, A. J. Jr.

    2014-03-01

    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.

  19. The Influence of Large Solar Proton Events on the Atmosphere

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.

    2012-01-01

    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.

  20. Influence of Industrialization in the Campinas Rural Region.

    ERIC Educational Resources Information Center

    Ferrari, Alfonso Trujillo

    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…

  1. Interactive coupling of regional atmosphere with biosphere in the new generation regional climate system model REMO-iMOVE

    NASA Astrophysics Data System (ADS)

    Wilhelm, C.; Rechid, D.; Jacob, D.

    2014-06-01

    The main objective of this study is the coupling of the regional climate model REMO with a new land surface scheme including dynamic vegetation phenology, and the evaluation of the new model version called REMO with interactive MOsaic-based VEgetation: REMO-iMOVE. First, we focus on the documentation of the technical aspects of the new model constituents and the coupling mechanism. The representation of vegetation in iMOVE is based on plant functional types (PFTs). Their geographical distribution is prescribed to the model which can be derived from different land surface data sets. Here, the PFT distribution is derived from the GLOBCOVER 2000 data set which is available on 1 km × 1 km horizontal resolution. Plant physiological processes like photosynthesis, respiration and transpiration are incorporated into the model. The vegetation modules are fully coupled to atmosphere and soil. In this way, plant physiological activity is directly driven by atmospheric and soil conditions at the model time step (two minutes to some seconds). In turn, the vegetation processes and properties influence the exchange of substances, energy and momentum between land and atmosphere. With the new coupled regional model system, dynamic feedbacks between vegetation, soil and atmosphere are represented at regional to local scale. In the evaluation part, we compare simulation results of REMO-iMOVE and of the reference version REMO2009 to multiple observation data sets of temperature, precipitation, latent heat flux, leaf area index and net primary production, in order to investigate the sensitivity of the regional model to the new land surface scheme and to evaluate the performance of both model versions. Simulations for the regional model domain Europe on a horizontal resolution of 0.44° had been carried out for the time period 1995-2005, forced with ECMWF ERA-Interim reanalyses data as lateral boundary conditions. REMO-iMOVE is able to simulate the European climate with the same quality as the parent model REMO2009. Differences in near-surface climate parameters can be restricted to some regions and are mainly related to the new representation of vegetation phenology. The seasonal and interannual variations in growth and senescence of vegetation are captured by the model. The net primary productivity lies in the range of observed values for most European regions. This study reveals the need for implementing vertical soil water dynamics in order to differentiate the access of plants to water due to different rooting depths. This gets especially important if the model will be used in dynamic vegetation studies.

  2. Assessing the contribution of natural sources to regional atmospheric mercury budgets

    SciTech Connect

    Gustin, M.S.; Lindberg, S.E.

    1997-12-31

    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.

  3. Atmosphere dynamics of the active region NOAA 11024

    E-print Network

    Kondrashova, N N; Chornogor, S N; Khomenko, E V; 10.1007/s11207-012-0212-5

    2012-01-01

    We present results of the study of chromospheric and photospheric line-of-sight velocity fields in the young active region NOAA 11024. Multi-layer, multi-wavelength observational data were used for the analysis of the emerging flux in this active region. Spectropolarimetric observations were carried out with the telescope THEMIS on Tenerife (Canary Islands) on 4 July 2009. In addition, space-borne data from SOHO/MDI, STEREO and GOES were also considered. The combination of data from ground- and space-based telescopes allowed us to study the dynamics of the lower atmosphere of the active region with high spatial, spectral, and temporal resolutions. THEMIS spectra show strong temporal variations of the velocity in the chromosphere and photosphere for different activity features: two pores, active and quiet plage regions, and two surges. The range of variations of the chromospheric line-of-sight velocity at the heights of formation of the H-alpha core was extremely large. Both upward and downward motions were ob...

  4. Seasonal emanation of radon at Ghuttu, northwest Himalaya: Differentiation of atmospheric temperature and pressure influences.

    PubMed

    Kamra, Leena

    2015-11-01

    Continuous monitoring of radon along with meteorological parameters has been carried out in a seismically active area of Garhwal region, northwest Himalaya, within the frame work of earthquake precursory research. Radon measurements are carried out by using a gamma ray detector installed in the air column at a depth of 10m in a 68m deep borehole. The analysis of long time series for 2006-2012 shows strong seasonal variability masked by diurnal and multi-day variations. Isolation of a seasonal cycle by minimising short-time by 31 day running average shows a strong seasonal variation with unambiguous dependence on atmospheric temperature and pressure. The seasonal characteristics of radon concentrations are positively correlated to atmospheric temperature (R=0.95) and negatively correlated to atmospheric pressure (R=-0.82). The temperature and pressure variation in their annual progressions are negatively correlated. The calculations of partial correlation coefficient permit us to conclude that atmospheric temperature plays a dominant role in controlling the variability of radon in borehole, 71% of the variability in radon arises from the variation in atmospheric temperature and about 6% of the variability is contributed by atmospheric pressure. The influence of pressure variations in an annual cycle appears to be a pseudo-effect, resulting from the negative correlation between temperature and pressure variations. Incorporation of these results explains the varying and even contradictory claims regarding the influence of the pressure variability on radon changes in the published literature. Temperature dependence, facilitated by the temperature gradient in the borehole, controls the transportation of radon from the deep interior to the surface. PMID:26319089

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

    NASA Astrophysics Data System (ADS)

    Bolshunova, Tatiana; Ivan, Podkozlin

    2013-04-01

    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.

  6. 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)

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

    1985-01-01

    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.

  7. The influence of ionization events on atmospheric ozone

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.

    1979-01-01

    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.

  8. Factors influencing atmospheric concentrations of polybrominated diphenyl ethers in Japan.

    PubMed

    Dien, Nguyen Thanh; Hirai, Yasuhiro; Miyazaki, Toru; Sakai, Shin-Ichi

    2016-02-01

    We used polybrominated diphenyl ether (PBDE) data in air at 38 sites across Japan (2009-2012), which were measured by the Japan Ministry of Environment (JMOE), to elucidate the time trend and seasonality of atmospheric PBDEs. In order to address few (7% for BDE-47) to many (63% for BDE-153 and 183) non-detect data, Tobit model, also called a censored regression model was used. The model revealed that the concentrations of PBDE congeners were influenced by a combination of year, temperature, rainfall rate, and population density. Greater declines were observed for BDE-47, -99, -153 and -183 (-21, -25, -17, -23%/year, p < 0.05) than for BDE-209 (-6%/year, p = 0.065). These trends were consistent with the estimated trends of penta-, octa- and deca-BDE contained in in-use products based on domestic demand for PBDEs in Japan and product lifespan. Seasonal patterns were opposite for light congeners (BDE-47 and -99), which increased with temperature, and heavy congeners (BDE-183, and -209), which decreased with temperature. Temperature-dependent emission (evaporation) for light congeners and temperature-independent emission (abrasion) for heavy congeners, coupled with seasonality of atmospheric boundary layer height, might explain these seasonal patterns. Human population density showed a positive correlation with all PBDE congener concentrations, whereas PBDEs showed negative correlation with rainfall rate. PMID:26583289

  9. Atmospheric energetics in regions of intense convective activity

    NASA Technical Reports Server (NTRS)

    Fuelberg, H. E.

    1977-01-01

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

  10. Natural sources of atmospheric aerosols influencing air quality across Europe.

    PubMed

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

    2014-02-15

    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

  11. Regional forecasting with global atmospheric models; Final report

    SciTech Connect

    Crowley, T.J.; Smith, N.R.

    1994-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

  13. The influence of atmospheric circulation on plant phenological phases in central and eastern Europe

    NASA Astrophysics Data System (ADS)

    Aasa, Anto; Jaagus, Jaak; Ahas, Rein; Sepp, Mait

    2004-10-01

    The objective of this study is to analyse relationships between the start dates of spring phenological phases and large-scale atmospheric circulation patterns. The timing of phenological phases in temperate zones is driven by temperature, and temperature regime is generally determined by atmospheric circulation. The database analysed consists of the first dates of flowering of coltsfoot (Tussilago farfara L.), of birch (Betula pendula Roth.) leaf unfolding and of flowering of lilac (Syringa vulgaris L.); the North Atlantic oscillation (NAO) and the Arctic oscillation (AO) indices, frequencies of the circulation forms classified by Vangengeim and Girs, and of the groups of Grosswetterlagen presented by Hess and Brezowsky. The study area covers central and eastern Europe, and the period considered is 1951-98.The results show that the influence of the westerly airflow is more pronounced in the winter half-year, and weakens and even disappears as spring advances. Phases have the highest correlation with NAO and AO indices during winter (December-March) and the first three months of the year (January-March), which have correlations stronger than -0.5 in the Baltic Sea region. Among the phenological phases, flowering of coltsfoot is the most strongly correlated with the NAO and AO indices, followed by leafing of birch and flowering of lilac. Airflow from the north and from the east has a greater influence in springtime, particularly in the northernmost and southernmost regions of the study area.

  14. Regional High-resolution Coupled Atmosphere Ocean Modelling in the North Sea Region

    NASA Astrophysics Data System (ADS)

    Dumenil-Gates, Lydia; Bülow, Katharina; Ganske, Anette; Heinrich, Hartmut; Klein, Birgit; Klein, Holger; Möller, Jens; Rosenhagen, Gudrun; Schade, Nils; Hüttl-Kabus, Sabine; Tinz, Birger

    2015-04-01

    The analysis of climate projections in the North Sea area is one of the research tasks of the research programme KLIWAS of the German Federal Ministry of Transport and Digital Infrastructure. A multi-model ensemble of three coupled regional atmosphere-ocean models was set up comprising very high resolution simulations for the German coastal regions of the North Sea and the Baltic to represent the complex land-sea-atmosphere conditions in the region. The ensemble consists of simulations made in cooperation with the Swedish Meteorological and Hydrological Institute, the Climate Service Centre and the Max-Planck-Institute for the period of 1950 to 2100. The KLIWAS project thereby adds coupled models to the band-width of possible future climate conditions in the atmosphere as given by the ENSEMBLES project, which were also analyzed. The coupled results are evaluated for present-day climate using a North Sea climatology of maritime conditions at a matching high resolution. In the future climate, while air and water temperatures will rise to the year 2100, the mean wind speed does not show a significant trend, but large decadal variability. The frequency of occurrence of westerly wind directions increases in the majority of simulations and results in an increase of significant wave height in the eastern parts of the North Sea. In an interdisciplinary approach, these results are used to provide regional to local information for the development of adaptation strategies for the estuary, and climate-proofing of infrastructure in the wider context of the project.

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

    NASA Technical Reports Server (NTRS)

    Mohanakumar, K.

    1989-01-01

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

  16. Atmospheric NO sub 3 2. Observations in polar regions

    SciTech Connect

    Solomon, S.; Sanders, R.W.; Mount, G.H.; Carroll, M.A.; Jakoubek, R.O.; Schmeltekopf, A.L. )

    1989-11-20

    Stratospheric NO{sub 3} is expected to depend strongly upon two major factors: solar illumination and temperature. This paper presents observations in the polar regions that confirm the influence of both of these on the NO{sub 3} column abundance. Measurements of the absorption of incoming lunar radiation near 662 nm as the sun rises exhibit large changes that apparently reflect the rapid photolysis of NO{sub 3}. The increase in upper stratosphere temperature that occurs in early spring in polar regions should also affect the seasonal changes in stratospheric NO{sub 3} abundances. Observations of stratospheric NO{sub 3} at 76.5{degree}N in early February are contrasted with those obtained at 77.8{degree}S in late August and September. Large seasonal differences in stratospheric temperatures between these two locations and times are shown to be in excellent agreement with the observed NO{sub 3} column amounts, providing further support for current understanding of the factors controlling the stratospheric NO{sub 3} abundance and its variability. These findings provide further evidence against a stratospheric scavenger'' for NO{sub 3}, even in polar latitudes, where the scavenger effect was believed to be most pronounced. {copyright} American Geophysical Union 1989

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

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

    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°.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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).

  19. Isotopic Studies of Ice Core Nitrate and Atmospheric Nitrogen Oxides in Polar Regions

    E-print Network

    Winglee, Robert M.

    Isotopic Studies of Ice Core Nitrate and Atmospheric Nitrogen Oxides in Polar Regions Julia C ____________________________ #12;University of Washington Abstract Isotopic Studies of Ice Core Nitrate and Atmospheric Nitrogen and present changes in atmospheric NOx (NO + NO2) is possible through measurements of nitrate (NO3 - or nitric

  20. Atmospheric effects on NOAA AVHRR data over Sahelian regions

    NASA Technical Reports Server (NTRS)

    Soufflet, V.; Tanre, D.; Begue, A.; Podaire, A.; Deschamps, P. Y.

    1991-01-01

    Variable atmospheric conditions have a significant impact on satellite monitoring of vegetation in the Sahelian zone of Africa. The effects of atmospheric O3, H2O, and aerosols on spectral, directional reflectances and derived measures, such as the normalized difference vegetation index are discussed using a sensitivity study. An atmospheric correction scheme is presented based on measurements of optical thicknesses from the ground and is applied to NOAA AVHRR data. The use of the reflectance of the ocean surface close to the terrestrial target to estimate atmospheric effects on terrestrial reflectance is also discussed.

  1. Regional scale evaporation and the atmospheric boundary layer

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

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

    E-print Network

    Castro, Christopher L.

    Dynamical downscaling: Assessment of value retained and added using the Regional Atmospheric Modeling System (RAMS) Christopher L. Castro, Roger A. Pielke Sr., and Giovanni Leoncini Department by dynamical downscaling is quantitatively evaluated by considering the spectral behavior of the Regional

  3. The Role of Regional Atmospheric Circulation in Shaping Abrupt Climate Reorganization in Africa

    NASA Astrophysics Data System (ADS)

    Skinner, C. B.; Poulsen, C. J.

    2014-12-01

    During the late Pleistocene and early to mid-Holocene, northern Africa experienced sufficient rainfall to support annual vegetation and widespread lakes. This humid climate state is known as the African Humid Period (AHP). Geologic evidence suggests that the transitions into and out of the AHP occurred rapidly, potentially within a span of decades to centuries. Despite considerable effort to understand the response of precipitation during the AHP, the mechanisms by which the abrupt climate transitions over Africa occurred remain unclear. Here, we use an ensemble of coupled earth system model experiments to explore the role of regional and synoptic-scale atmospheric circulation in Africa during the AHP. Specifically, we analyze characteristics of transient, synoptic-scale weather systems and quantify the relationship between these systems and rainfall in Africa. Preliminary results show that orbital forcing-driven changes in insolation during the AHP weaken surface meridional temperature gradients over Africa and modify the characteristics and energetics of synoptic-scale phenomena, including African easterly waves (AEWs). These results indicate a potential shift in the atmospheric processes that influence precipitation between humid and arid states in northern Africa. We explore whether the insolation-driven changes in local atmospheric processes, in particular the changes in AEWs, contribute to rapid climate reorganization in Africa.

  4. a New, Regional-Scale Coupled Atmosphere-Ecosystem Model: Formulation and Results

    NASA Astrophysics Data System (ADS)

    Moorcroft, P. R.; Medvigy, D. M.; Avissar, R.; Walko, R. L.

    2004-05-01

    The formulation of self-consistent and computationally efficient atmosphere-ecosystem models requires the bridging of a wide range of spatial and temporal scales. Disturbance events such wind-throw, fire and land-use change give rise to significant sub-grid scale heterogeneity in ecosystem structure and function at a variety scales ranging down to the the size of an individual canopy tree, far below the resolution of both climate and numerical weather prediction models. Moreover, over decadal timescales, the spatial distribution of this heterogeneity is dynamic due to the successional dynamics that follow disturbance events within ecosystems. To address this problem, we have developed the Ecosystem Demography Land Surface Model (ED-LSM), an integrated biosphere model that incorporates plant community dynamics, soil carbon and nitrogen biogeochemistry and land surface biophysics. The fast timescale fluxes of carbon, water and energy between the ecosystem and the atmosphere are captured using the leaf photosynthesis and soil decomposition modules of the Ecosystem Demography (ED) model coupled to a multi-leaf layer, multi-soil layer implementation of the LEAF-2 biophysical scheme. Long term changes in the biophysical, ecological and biogeochemical structure of the ecosystem are captured using the ED model's system of size- and age-structured partial differential equations that track the changes in the vertical and horizontal heterogeneity of above and below ground ecosystem structure that result from ecosystem responses to the atmosphere that play out over years, decades and centuries. The model can be run both off-line and coupled to the Regional Atmospheric Modeling System (RAMS), which simulates both atmospheric dynamics and tracer transport of carbon dioxide. We have carried out coupled simulations of the model in temperate, tropical and boreal regions. Comparison of our results with observations from eddy-flux towers and meteorological stations highlights the model's ability to capture the influence of the heterogeneous land surface on the dynamics of the land-surface interaction in these different regions on time scales ranging from the synoptic to the decadal.

  5. A Regional Scale Coupled Atmosphere-Ecosystem Model: Formulation and Results

    NASA Astrophysics Data System (ADS)

    Medvigy, D.; Moorcroft, P. R.; Albani, M.; Avissar, R.; Walko, R. L.

    2004-12-01

    The formulation of self-consistent and computationally efficient atmosphere-ecosystem models requires the bridging of a wide range of spatial and temporal scales. Disturbance events such wind-throw, fire and land-use change give rise to significant sub-grid scale heterogeneity in ecosystem structure and function at a variety scales ranging down to the the size of an individual canopy tree, far below the resolution of both climate and numerical weather prediction models. Moreover, over decadal timescales, the spatial distribution of this heterogeneity is dynamic due to the successional dynamics that follow disturbance events within ecosystems. To address this problem, we have developed the Ecosystem Demography Land Surface Model (ED-LSM), an integrated biosphere model that incorporates plant community dynamics, soil carbon and nitrogen biogeochemistry and land surface biophysics. The fast timescale fluxes of carbon, water and energy between the ecosystem and the atmosphere are captured using the leaf photosynthesis and soil decomposition modules of Ecosystem Demography (ED) model coupled to a multi-leaf layer, multi-soil layer implementation of the LEAF-2 biophysical scheme. Long term changes in the biophsyical, ecological and biogeochemical structure of the ecosystem are captured using the ED model's system of size- and age-structured partial differential equations that track the changes in the vertical and horizontal heterogeneity of above and below ground ecosystem structure that result from ecosystem responses to the atmosphere that play out over years, decades and centuries. The model can be run both off-line and coupled to the Regional Atmospheric Modeling System (RAMS), which simulates both atmospheric dynamics and tracer transport of carbon dioxide. We have carried out coupled simulations of the model in temperate, tropical and boreal regions. Comparison of our results with observations from eddy-flux towers and meteorological stations highlights the models ability to capture the influence of the heterogeneous land surface on the dynamics of the land-surface interaction in these different regions on time scales ranging from the synoptic to the decadal.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  7. Influence of Atmospheric CO2 Variation on Strom Track Behavior

    NASA Astrophysics Data System (ADS)

    Martynova, Yuliya; Krupchatnikov, Vladimir

    2015-04-01

    The storm tracks are the regions of strong baroclinicity where surface cyclones occur. The effect of increase with following decrease of anthropogenic load on storm tracks activity in the Northern Hemisphere was studied. The global climate system model of intermediate complexity ('Planet Simulator', Fraedrich K. et al., 2005) was used in this study. Anthropogenic forcing was set according to climatic scenario RCP8.5 continued till 4000 AD with fixed CO2 concentration till 3000 AD and linear decrease of anthropogenic load to preindustrial value at two different rates: for 100 and 1000 years. Modeling data analysis showed meridional shift of storm tracks due to atmospheric CO2 concentration variation. When CO2 concentration increases storm tracks demonstrate poleward shifting. When CO2 concentration decreases to preindustrial value storm tracks demonstrate a tendency to equator-ward shifting. Storm tracks, however, don't recover their original activity and location to the full. This manifests itself particularly for 'fast' CO2 concentration decrease. Heat and moisture fluxes demonstrate the same behavior. In addition, analysis of eddy length scale (Kidston J. Et al., 2011) showed their increase at mid-latitudes and decrease at tropic latitudes due to intensive CO2 concentration increase. This might cause poleward shift of mid-latitude jets. Acknowledgements. This work is partially supported by SB RAS project VIII.80.2.1, RFBR grant 13-05-12034, 13-05-00480, 14-05-00502 and grant of the President of the Russian Federation. Fraedrich K., Jansen H., Kirk E., Luksch U., and Lunkeit F. The Planet Simulator: Towards a user friendly model // Meteorol. Zeitschrift. 2005, 14, 299-304. Kidston J., Vallis G.K., Dean S.M., Renwick J.A. Can the increase in the eddy length scale ander global warming cause the poleward shift of the jet streams? // J. Climate. 2011, V.24. P. 3764-3780.

  8. Short-term production and synoptic influences on atmospheric 7

    E-print Network

    energetic nucleons (mostly protons and a particles) of extraterrestrial origin, continuously bombard the Earth's atmosphere, resulting in various physical and chemical effects [see, e.g., Dorman, 2004 Be (half-life T1/2 %53.22 days), which is a product of spallation of atmospheric O and N nuclei caused

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

    E-print Network

    Mende, Stephen B.

    Longitudinal variation of the E-region electric fields caused by atmospheric tides S. L. England,1 with the longitudinal variation in the strength of diurnal tides that drive the E-region dynamo. This indicates a strong by atmospheric tides, Geophys. Res. Lett., 33, L21105, doi:10.1029/2006GL027465. 1. Introduction [2] While

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

    NASA Astrophysics Data System (ADS)

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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    SciTech Connect

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

    2014-05-01

    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 (PM{sub 10}) 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{sup 3}, and those for PM{sub 10} were 42.8 and 68.9 ng/m{sup 3}, in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM{sub 10} 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 PM{sub 10} 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{sub N}/Yb{sub N}, La{sub N}/Sm{sub N}, Gd{sub N}/Yb{sub N}). - Highlights: • TSP and PM{sub 10} samples were collected to analyze the levels and distributions of REE. • Enrichment factors indicated that REE enrichment was caused by anthropogenic sources. • The distribution of REEs showed a strong gradient in the prevailing wind direction. • Obvious fractionation between LREEs and HREEs is observed in atmospheric particulates.

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

    PubMed

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

    2015-04-01

    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

  14. Emissions from vegetation fires and their influence on atmospheric composition over the Amazon Basin (Invited)

    NASA Astrophysics Data System (ADS)

    Andreae, M. O.; Artaxo, P.; Bela, M. M.; de Freitas, S. R.; Gerbig, C.; Longo, K. M.; Wiedemann, K. T.; Wofsy, S. C.

    2010-12-01

    Over the past decades, several campaigns have been conducted in the Amazon Basin, during which the emissions from biomass burning were characterized. Other campaigns, as well as remote sensing studies, have produced clear evidence that the budget of traces gases (including CO2) and aerosols over the Basin are strongly perturbed by vegetation fires. We will briefly review these studies and present some recent measurements made during the the Balanço Atmosférico Regional de Carbono na Amazônia (BARCA) aircraft measurement program, which consisted of two aircraft campaigns during November-December 2008 (BARCA-A) and May-June 2009 (BARCA-B). The measurements covered the altitude range from the surface up to about 4500 m, and spanned across the Amazon Basin. While our results confirm the importance of biomass burning for the atmospheric composition over the Amazon Basin in general, they also highlight some complexities. One is the influence of transatlantic transport: Amazonia is downwind of massive fire regions in Africa, and depending on season and locality, these can make an important contribution to the trace gas and aerosol burden over the Amazon Basin. Another difficulty arises from the fact that representative emission ratios for CO relative to CO2 are difficult to obtain in the field, owing to the influence of biospheric exchange on the distribution of CO2 concentrations. The consequences of these and other uncertainties for a quantitative assessment of the sources of trace gases over Amazonia and for the estimation of carbon exchange with the biosphere will be discussed.

  15. Effect of East Asia summer blocking on the atmospheric circulation over the region

    NASA Astrophysics Data System (ADS)

    Ahn, Joong-Bae; Park, Yong-Jun

    2015-04-01

    The influence of the boreal summer blocking on atmospheric circulation in East Asia was examined. The summer blocking occurred mostly in North Europe, Ural region, Sea of Okhotsk (OK), and northeastern Pacific. The summer blocking was the major mode in these four regions according to principal component analysis using 500 hPa geopotential heights. Among the four blocking regions, OK blocking frequencies (OK BFs) showed negative and positive correlations with summer temperature and precipitation of Northeast Asia centered around the East Sea/Sea of Japan, respectively. In particular, the OK BF had a statistically significant correlation coefficient of -0.54 with summer temperatures in the Korean Peninsula. This indicates that the summer temperature and precipitation in this region were closely related to the OK blocking. According to the composite analysis for the years of higher-than-average BF (positive BF years), the OK High became stronger and expanded, while the North Pacific High was weakened over the Korean Peninsula and Japan and an anomalously deep trough was developed in the upper layer (200 hPa). As the cool OK High expanded, the temperature decreased over Northeast Asia centered around the East Sea/Sea of Japan and the lower level (850 hPa) air converged cyclonically, resulting in the increased precipitation, which induced the divergence in the upper layer and thereby strengthened the jet stream. Thus, the boreal summer OK blocking systematically influencing the area as the most dominant mode. Acknowledgements This work was carried out with the support of Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under grant project PJ009353 and Korea Meteorological Administration Research and Development Program under grant CATER 2012-3100, Republic of Korea.

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

    E-print Network

    Jackman, Charles H.

    Long-term middle atmospheric influence of very large solar proton events Charles H. Jackman,1 June 2009. [1] The Whole Atmosphere Community Climate Model (WACCM3) has been used to study the long-term (more than a few months) effects of solar proton events (SPEs). Extremely large solar proton events

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

    SciTech Connect

    Leung, Lai R.; Qian, Yun

    2009-02-12

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    SciTech Connect

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

    2000-05-01

    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.

  20. Atmospheric profiles of CO? as integrators of regional scale exchange 

    E-print Network

    Smallman, Thomas Luke

    2014-06-30

    -SPA (R² = 0.67, RMSE = 3.5 ppm, bias = 0.58 ppm). Analysis of CO? tracers at tall tower Angus show an increase in the seasonal error between WRF-SPA simulated atmospheric CO? and observations, which coincides with simulated cropland harvest. WRF-SPA does...

  1. 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...

  2. Medicanes in an ocean-atmosphere coupled regional climate model

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Reiter, Reinhold

    1989-01-01

    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.

  4. 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...

  5. Quantifying the influences of atmospheric stability on air pollution in Lanzhou, China, using a radon-based stability monitor

    NASA Astrophysics Data System (ADS)

    Chambers, Scott D.; Wang, Fenjuan; Williams, Alastair G.; Xiaodong, Deng; Zhang, Hua; Lonati, Giovanni; Crawford, Jagoda; Griffiths, Alan D.; Ianniello, Antonietta; Allegrini, Ivo

    2015-04-01

    Commercially-available "stability monitors" based on in situ atmospheric radon progeny measurements remain underutilised as a tool for urban pollution studies, due in part to difficulties experienced in relating their standard output directly to the atmospheric mixing state in a consistent manner. The main confounding factor has been a lack of attention to the fact that the observed near-surface atmospheric radon concentration includes large synoptic and fetch-related components in addition to the local stability influence. Here, a technique recently developed for stability classification using a research-quality dual-flow-loop two-filter radon detector is adapted for use with a commercially-available radon-based stability monitor. Performance of the classification scheme is then tested in Lanzhou, China, a topographically-complex region renowned for low mean annual wind speeds (0.8 m s-1) and winter stagnation episodes. Based on an 11-month composite, a factor of seven difference is estimated between peak NOx concentrations in the city's industrial region and a rural background location under stable conditions. The radon-based scheme is evaluated against the Pasquil-Gifford "radiation" (PGR) scheme, and assigns pollutant concentrations more consistently between defined atmospheric stability states than the PGR scheme. Furthermore, the PGR scheme consistently underestimates all peak pollutant concentrations under stable conditions compared with the radon-based scheme, in some cases (e.g. CO in the industrial region) by 25%.

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

    SciTech Connect

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

    2005-03-18

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

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  8. 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

  9. Regional Assimilation of NASA Atmospheric Infrared Sounder (AIRS) Data

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  10. Carbonaceous aerosols influencing atmospheric radiation: Black and organic carbon

    SciTech Connect

    Penner, J.E.

    1994-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  12. Processes influencing rainfall features in the Amazonian region

    NASA Astrophysics Data System (ADS)

    Gerken, T.; Chamecki, M.; Fuentes, J. D.; Katul, G. G.; Fitzjarrald, D. R.; Manzi, A. O.; Nascimento dos Santos, R. M.; von Randow, C.; Stoy, P. C.; Tota, J.; Trowbridge, A.; Schumacher, C.; Machado, L.

    2014-12-01

    The Amazon is globally unique as it experiences the deepest atmospheric convection with important teleconnections to other parts of the Earth's climate system. In the Amazon Basin a large fraction of the local evapotranspiration is recycled through the formation of deep convective precipitating storms. Deep convection occurs due to moist thermodynamic conditions associated with elevated amounts of convective available potential energy. Aerosols invigorate the formation of convective storms in the Amazon via their unique concentrations, physical size, and chemical composition to activate into cloud condensation nuclei (CCN), but important aspects of aerosol/precipitation feedbacks remain unresolved. During the wet season, low atmospheric aerosol concentrations prevail in the pristine tropical air masses. These conditions have led to the Green Ocean hypothesis, which compares the clean tropical air to maritime air-masses and emphasizes biosphere-atmosphere feedbacks, to explain the features of the convective-type rainfall events in the Amazon. Field studies have been designed to investigate these relationships and the development of mesoscale convective systems through the Green Ocean Amazon project and the GOAmazon Boundary Layer Experiment. From March to October 2014 a field experiment was conducted at the Cuieiras Biological Reserve (2°51' S, 54°58' W), 80 km north of the city of Manaus, Brazil. This investigation spans the biological, chemical, and physical conditions influencing emissions and reactions of precursors (biogenic and anthropogenic volatile organic compounds, VOCs), formation of aerosols and CCNs and transport out of the ABL, and their role in cloud formation and precipitation triggers. In this presentation we will show results on the magnitude turbulent fluxes of latent and sensible heat, CCN concentrations, and rain droplet size distribution for both the wet and dry season. Such influencing factors on precipitation, will be contrasted with the vertical contoured frequency-by-altitude diagrams (CFADs) for representative mesoscale convective systems for dry and wet seasons. Rainfall yields from mesoscale convective storms will be linked to the antecedent thermodynamic conditions derived from analyses of upper air soundings.

  13. Real time GPS data processing for regional atmospheric delay derivation

    NASA Astrophysics Data System (ADS)

    Jarlemark, Per O. J.; Johansson, Jan M.; Stoew, Borys; Elgered, Gunnar

    2002-08-01

    We have developed a GPS data processing software and demonstrate that by using receivers in an area of approximately 800 × 400 km we can produce estimates of the atmospheric zenith total delay (ZTD) with a latency of a few seconds. It is based on a Kalman filter which simultaneously estimates clock offsets and satellite coordinates. The ZTD quality is typically 15 mm in terms of rms difference to post-processed ZTD time series. This level of uncertainty is useful in many navigation applications and if an additional reduction in the uncertainty can be obtained the usefulness for short term weather forecasting could be significant.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    Himalayan Plateau is surrounded by regions with high natural and anthropogenic aerosol emissions that have a strong impact on regional climate. This is particularly critical for the Himalayan glaciers whose equilibrium is also largely influenced by radiative direct and indirect effects induced by aerosol burden. This work focuses on the spatial and vertical distribution of different aerosol types, their seasonal variability and sources. The analysis of the 2007-2010 yr of CALIPSO vertically resolved satellite 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 they are distributed mainly north (with a main contribution from the Gobi and Taklamakan deserts) and west of the Tibetan Plateau (originating from the deserts of South-West Asia and advected by the westerlies). Above the Himalayas the dust amount is minor but still not negligible (detectable in around 20% of the measurements), and transport from more distant deserts (Sahara and Arabian Peninsula) is important. Smoke aerosol, produced mainly in North India and East 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 maxima of occurrence in spring. The study also highlights relevant interannual differences, showing a larger presence of aerosol in the region during 2007 and 2008 yr.

  15. Predictability of convective precipitation for West Africa: Does the land surface influence ensemble variability as much as the atmosphere?

    NASA Astrophysics Data System (ADS)

    Maurer, Vera; Kalthoff, Norbert; Gantner, Leonhard

    2015-04-01

    In recent studies, the importance of the influence of the land surface and especially of soil-moisture heterogeneities on convective systems and convection initiation in the Sahel was established. This investigation aims at comparing the land-surface part of the influence on convection with that of the atmosphere. For this reason, realistic land-surface perturbations were generated to set up an ensemble of convection-permitting simulations that contains atmospheric as well as land-surface perturbations. The simulation of precipitation by the ensemble proved to be sufficiently realistic. By comparing precipitation forecasts of individual members, it was found that the effectiveness of soil perturbations in generating ensemble variability is as large as the effectiveness of the atmosphere. This means that the representation of the land surface, reflected by parameters such as the soil-type distribution and absolute soil moisture as well as its heterogeneities, is as important for the predictability of convective precipitation in the Sahel region as atmospheric conditions. However, soil perturbations do not determine the day on which larger convective systems occur. This rather depends on larger-scale factors such as African easterly waves, the strength of the monsoon flow as well as the location and intensity of the heat low. In each case, it is a combination of different processes determining the occurrence of convection and convective precipitation.

  16. Impacts of land-atmosphere coupling on regional rainfall and convection

    NASA Astrophysics Data System (ADS)

    Zheng, Yue; Kumar, Anil; Niyogi, Dev

    2015-05-01

    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.

  17. Influence of modified atmosphere packaging on 'Star Ruby' grapefruit phytochemicals.

    PubMed

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

    2015-01-28

    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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  19. Regional forecasting with global atmospheric models; Third year report

    SciTech Connect

    Crowley, T.J.; North, G.R.; Smith, N.R.

    1994-05-01

    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.

  20. MODELING REGIONAL-SCALE ATMOSPHERIC MERCURY USING RELMAP

    EPA Science Inventory

    The Regional Lagrangian Model of Air Pollution (RELMAP) is used to simulate the emission, transport and diffusion, chemical transformation, and wet and dry deposition of elemental mercury gas, divalent mercury gas and particulate mercury. ased on recent modeling advances in Europ...

  1. Deuterium excess in the atmospheric water vapour of a Mediterranean coastal wetland: regional vs. local signatures

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Stable isotopes of water vapour represent a powerful tool for tracing atmospheric vapour 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 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 vapour of a Mediterranean coastal wetland exposed to high evaporation (Camargue, Rhône River delta, France). The mean composition of atmospheric vapour (?v) is ?18O = -14.66 ‰ and ?D = - 95.4 ‰, with data plotting clearly above the local meteoric water line on a ?18O-?D plot, and an average deuterium excess (d) of 21.9 ‰. Important diurnal d variations are observed, and an hourly time scale analysis is necessary to interpret the main processes involved in its variability. After having classified the data according to air mass back trajectories, we analyse the average daily cycles relating to the two main meteorological situations, i.e. air masses originating from North Atlantic Ocean and Mediterranean Sea. In both situations, we show that diurnal fluctuations are driven by (1) the influence of local evaporation, culminating during daytime, and leading to an increase in absolute water vapour concentration associated to a ?v enrichment and d increase; (2) vertical air mass redistribution when the Planetary Boundary Layer collapses in the evening, leading to a d decrease, and (3) dew formation during the night, producing a ?v depletion with d remaining stable. Using a two-component mixing model, we calculate the average composition of the locally evaporated vapour (?E). We find higher d(E) under North Atlantic air mass conditions, which is consistent with lower humidity conditions. We also suggest that ?v measured when the PBL collapses is the most representative of a regional signal. Strong, cold and dry winds coming from the north bring an isotopically depleted vapour, while light, warm and wet winds coming from the south bring an isotopically enriched vapour. Under northern conditions, a strong advection rate dilutes the contribution of the locally evaporated vapour (?E) to the ambient moisture (?v). The higher d values measured under northern conditions, compared to the Mediterranean situation, thus results from the combination of a higher d in both local and regional vapour. This depiction of typical daily cycles of water vapour isotopic composition can be used as a framework for further quantitative analyses of vapour sources during specific days.

  2. On the formation of sulphuric acid - amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation

    NASA Astrophysics Data System (ADS)

    Paasonen, P.; Olenius, T.; Kupiainen, O.; Kurtén, T.; Petäjä, T.; Birmili, W.; Hamed, A.; Hu, M.; Huey, L. G.; Plass-Duelmer, C.; Smith, J. N.; Wiedensohler, A.; Loukonen, V.; McGrath, M. J.; Ortega, I. K.; Laaksonen, A.; Vehkamäki, H.; Kerminen, V.-M.; Kulmala, M.

    2012-10-01

    Sulphuric acid is a key component in atmospheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate particle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (JA2B2) at varying atmospherically relevant conditions with respect to concentrations of sulphuric acid ([H2SO4]), dimethylamine ([DMA]) and trimethylamine ([TMA]), temperature and relative humidity (RH). We also tested how the model results change if we assume that the clusters with two sulphuric acid and two amine molecules would act as seeds for heterogeneous nucleation of organic vapours (other than amines) with higher atmospheric concentrations than sulphuric acid. The modelled formation rates JA2B2 were functions of sulphuric acid concentration with close to quadratic dependence, which is in good agreement with atmospheric observations of the connection between the particle formation rate and sulphuric acid concentration. The coefficients KA2B2 connecting the cluster formation rate and sulphuric acid concentrations as JA2B2=KA2B2[H2SO4]2 turned out to depend also on amine concentrations, temperature and relative humidity. We compared the modelled coefficients KA2B2 with the corresponding coefficients calculated from the atmospheric observations (Kobs) from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of JA2B2 as a function of [H2SO4], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the traditional semi-empirical formulae based on sulphuric acid concentration only. The formation rates of clusters with two sulphuric acid and two amine molecules with different amine compositions (DMA or TMA or one of both) had different responses to varying meteorological conditions and concentrations of vapours participating in particle formation. The observed inverse proportionality of the coefficient Kobs with RH and temperature agreed best with the modelled coefficient KA2B2 related to formation of a cluster with two H2SO4 and one or two TMA molecules, assuming that these clusters can grow in collisions with abundant organic vapour molecules. In case this assumption is valid, our results suggest that the formation rate of clusters with at least two of both sulphuric acid and amine molecules might be the rate-limiting step for atmospheric particle formation. More generally, our analysis elucidates the sensitivity of the atmospheric particle formation rate to meteorological variables and concentrations of vapours participating in particle formation (also other than H2SO4).

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

    USGS Publications Warehouse

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

    2007-01-01

    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.

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

    E-print Network

    Knox, Ryan Gary

    2013-01-01

    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 ...

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Abkar, Mahdi; Porté-Agel, Fernando

    2015-03-01

    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.

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

    SciTech Connect

    Fu, Rong ); Del Genio, A.D.; Rossow, W.B. )

    1994-07-01

    The influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure is analysed along with the resulting effects on the occurrence of deep convection using National Meterological 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 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. In warm SST regions, CAPE > 0 regardless of assumptions about condensate loading. When SST <27[degrees]C, CAPE 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 [>=] 28[degrees]C in the absence of strong surface wind divergence or when strong surface wind convergence occurs even if SST < 27[degrees]. The anomalous suppression wind divergence or when strong surface wind convergence occurs even if SST < 27[degrees]C. The anomalous suppression of deep convection in the warm area of the equatorial west Pacific lying between the ITCZ and 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. 37 refs., 11 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  9. Spatial extent of the North American Monsoon: Increased cross-regional linkages via atmospheric pathways

    NASA Astrophysics Data System (ADS)

    Dominguez, Francina; Villegas, Juan Camilo; Breshears, David D.

    2009-04-01

    The North American monsoon is a key feature affecting summer climate over Southwestern North America. During the monsoon, evapotranspiration from the Southwest promotes transference of water to the atmosphere which is subsequently distributed across the continent - linking the SW to other regions via atmospheric hydrologic connectivity. However, the degree to which atmospheric connectivity redistributes monsoonal terrestrial moisture throughout the continent and its sensitivity to climate disturbances such as drought is uncertain. We tracked the trajectory of moisture evapotranspired within the semiarid Southwest during the monsoon season using a Lagrangian analytical model. Southwest moisture was advected north-east accounting for ˜15% of precipitation in adjacent Great Plains regions. During recent drought (2000-2003), this amount decreased by 45%. Our results illustrate that the spatial extent of the North American monsoon is larger than normally considered when accounting for hydrologic connectivity via soil moisture redistribution through atmospheric pathways.

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

    SciTech Connect

    Ramsdell, James V.; Rishel, Jeremy P.

    2006-07-01

    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.

  11. Permafrost Thaw and Redistribution of Carbon from Lands and Oceans to the Atmosphere: the East Siberian Region

    NASA Astrophysics Data System (ADS)

    Semiletov, I. P.; Shakhova, N. E.; Pipko, I.; Dudarev, O.; Charkin, A.

    2014-12-01

    Unlike other oceans, the Arctic Ocean is completely surrounded by permafrost, which is being degraded at an increasing rate under warming conditions most pronounced in East Siberian region and Alaska. The thaw and release of organic carbon (OC) from Arctic permafrost is postulated to be one of the most powerful mechanisms causing the net redistribution of carbon from lands and oceans to the atmosphere. The East Siberian Arctic shelf (ESAS) is the world's largest continental shelf, containing more than 80 % of the world oceans' subsea permafrost and the largest hydrocarbon reservoir on the planet, while the stability of this sequestered carbon, which exists primarily as CH4, is highly uncertain. This area is heavily influenced by subsea permafrost thaw, and CH4 seeps from subsea permafrost reservoirs under warming conditions. Various other phenomena influence the area, including coastal erosion, mostly caused by onshore permafrost/coastal ice complex thaw; the input of dissolved and particulate OC through the Lena, Indigirka, and Kolyma rivers. The ESAS is also of particular interest for its carbon-climate couplings because thawing of onshore and offshore permafrost leads to the CH4 and CO2 emission to the atmosphere. The overall goal of the current research is to provide a quantitative, observation-based assessment of the dynamics of different ESAS carbon cycle components with emphasize on the emission of CO2 and CH4 to the atmosphere under changing climatic and environmental conditions.

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

    PubMed Central

    Sugawara, Masayuki; Sadowsky, Michael J.

    2013-01-01

    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

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

    E-print Network

    Dabdub, Donald

    2008-01-01

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

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

    E-print Network

    Jimenez, Jose-Luis

    Author's personal copy Pollution influences on atmospheric composition and chemistry at high counts over Siberia and a more normal Canadian boreal forest fire season. Near surface arctic air of transport and chemistry were found to be broadly consistent with observations with a tendency towards under

  15. Atmospheric Environment 40 (2006) 52745297 Influence of the PBL scheme on high-resolution

    E-print Network

    2006-01-01

    Atmospheric Environment 40 (2006) 5274­5297 Influence of the PBL scheme on high in revised form 11 April 2006; accepted 11 April 2006 Abstract Planetary boundary layer (PBL) and land of three different surface/PBL schemes from the MM5 mesoscale meteorological model on the predicted

  16. On the Influence of OceanAtmosphere Interaction on the Arctic Oscillation

    E-print Network

    Robertson, Andrew W.

    On the Influence of Ocean­Atmosphere Interaction on the Arctic Oscillation in two General and Planetary Physics, University of California, Los Angeles January 17, 2001 J. Climate, sub judice \\Lambda experiments. Greenhouse­gas induced changes in sea­level pressure are found to project onto the AO in one

  17. Atmospheric sensitivity to roughness length in a regional atmospheric model over the Ohio-Tennessee River Valley

    NASA Astrophysics Data System (ADS)

    Quintanar, Arturo I.; Mahmood, Rezaul; Suarez, Astrid; Leeper, Ronnie

    2015-11-01

    The response of a regional atmospheric model to small changes in roughness length of two vegetation categories (crops and deciduous broadleaf forest) was analyzed for three synoptic events in June 2006. These were characterized by two convective events (June 11 and 22) and one prefrontal event (June 17). The responses of the model, for precipitation, equivalent potential temperature and wind field were notable in general. However, the response became muted as roughness lengths were increased or decreased. Atmospheric response to these changes varied for different convective events. A small dependence on roughness length was found for the sensible and latent heat fluxes and planetary boundary layer heights during the convective event of June 11. For the June 22 event, the model response was weaker for the crop-only and forest-only roughness length experiments compared to the response when both the crop and forest-only roughness length were changed in combination.

  18. The Vertical Extent of the Influence of the Land Surface Boundary on the Atmosphere Above

    NASA Technical Reports Server (NTRS)

    Molod, Andrea; Salmun, Haydee

    1998-01-01

    Heterogeneities in the land surface type on scales smaller than the typical General Circulation Model (GMC) grid size have long presented a challenge to properly modelling the impact of the subgrid scale variability on the grid scale. In particular, at some height above the heterogeneous vegetated surface the atmospheric properties (temperature, humidity, for example) become homogenized. This is an issue with implications for climate modelling as well as for the optimal use of field data for climate studies. There is evidence that the influence of the soil and/or vegetation properties extends well beyond the atmospheric surface layer. The present study is aimed at understanding the implications of this influence for a GCM's description of the coupling at the earth-atmosphere interface.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

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

    PubMed

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

    2015-10-01

    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. PMID:25601781

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  2. Climate change and climate systems influence and control the atmospheric dispersion of desert dust: implications for human health

    USGS Publications Warehouse

    Griffin, Dale W.

    2010-01-01

    The global dispersion of desert dust through Earth’s atmosphere is greatly influenced by temperature. Temporal analyses of ice core data have demonstrated that enhanced dust dispersion occurs during glacial events. This is due to an increase in ice cover, which results in an increase in drier terrestrial cover. A shorter temporal analysis of dust dispersion data over the last 40 years has demonstrated an increase in dust transport. Climate systems or events such as the North Atlantic Oscillation, the Indian Ocean subtropical High, Pacific Decadal Oscillation, and El Nino-Sothern Oscillation are known to influence global short-term dust dispersion occurrence and transport routes. Anthropogenic influences on dust transport include deforestation, harmful use of topsoil for agriculture as observed during the American Dust Bowl period, and the creation of dry seas (Aral Sea) and lakes (Lake Owens in California and Lake Chad in North Africa) through the diversion of source waters (for irrigation and drinking water supplies). Constituents of desert dust both from source regions (pathogenic microorganisms, organic and inorganic toxins) and those scavenged through atmospheric transport (i.e., industrial and agricultural emissions) are known to directly impact human and ecosystem health. This presentation will present a review of global scale dust storms and how these events can be both a detriment and benefit to various organisms in downwind environments.

  3. Yak dung combustion aerosols in the Tibetan Plateau: Chemical characteristics and influence on the local atmospheric environment

    NASA Astrophysics Data System (ADS)

    Chen, Pengfei; Kang, Shichang; Bai, Jiankun; Sillanpää, Mika; Li, Chaoliu

    2015-04-01

    The study of the source areas of atmospheric pollutants in the Tibetan Plateau (TP) - one of the most remote regions in the world - has raised a great deal of concern. It is generally considered that the majority of pollutants in this region are transported from outside the TP. This research investigated the water soluble elements and carbonaceous matter from aerosols emitted from yak dung combustion by local residents and re-analyzed previous OC and BC data at Nam Co - a remote area of the TP. The compositions of the water soluble elements of the studied aerosols were similar to those in precipitation and snow samples of the region under investigation. Some heavy metal elements (e.g. Cd and As) even had higher enrichment factor (EF) values (1793 and 2355, respectively) compared to those in precipitation and snow samples, implying that previously reported high EF values for precipitation and snow did not completely reflect the long-range transported pollutants from outside the TP. Accordingly, the contributions of local sources needed to be considered. Organic carbon (OC) and black carbon (BC) accounted for 55.2% and 3.63% of the studied aerosol, respectively. The OC/BC ratio of the studied aerosols was close to the corresponding value for the outdoor aerosols, further indicating the influence of local sources on the atmosphere of Nam Co. It was proposed that air masses from South Asia cause high BC concentrations in the Nam Co region. It was, however, discovered that air masses from the TP itself also induce high BC concentrations, suggesting that not all the BC of Nam Co was transported from South Asia. Therefore, it is proposed that pollutants of atmospheric aerosols of the Nam Co region were derived from a variety of sources from both the TP and outside. In other words, the influence of yak dung burning by local residents on the atmosphere of the TP cannot be overlooked. Correspondingly, long-range transported pollutants can penetrate into the inland TP only when intensified pollution events occur in South Asia.

  4. Contributions of long-range and regional atmospheric transport on pesticide concentrations along a transect crossing a mountain divide.

    PubMed

    Lavin, Karen S; Hageman, Kimberly J

    2013-02-01

    Twenty-one halogenated legacy and current-use pesticides and pesticide degradation products were measured in pine needles along a coast-to-coast transect that crossed the Southern Alps of New Zealand. Concentration profiles of nine pesticides were used to determine the influence of geographic sources on the atmospheric pesticide burden at the mountain sites. Pesticide concentration profiles were calculated for each source and mountain site by normalizing concentrations (adjusted for temperature at the site and air-needle partitioning) to the sum of all pesticide concentrations at the site. Each mountain site profile was compared to varying mixtures of the potential source profiles to determine the percent contribution of each source. The highest elevation mountain sites were primarily influenced by long-range, synoptic-scale northwesterly winds. Westerly upslope winds had little influence on any of the mountain sites. Easterly upslope winds from the Canterbury Plains, an agricultural region, strongly influenced the mountain sites within close proximity and had progressively less influence with distance. PMID:23252430

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

    E-print Network

    Zexian, Cao

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

  6. Regionally coupled atmosphere-ocean-sea ice-marine biogeochemistry model ROM: 1. Description and validation

    NASA Astrophysics Data System (ADS)

    Sein, Dmitry V.; Mikolajewicz, Uwe; Gröger, Matthias; Fast, Irina; Cabos, William; Pinto, Joaquim G.; Hagemann, Stefan; Semmler, Tido; Izquierdo, Alfredo; Jacob, Daniela

    2015-03-01

    The general circulation models used to simulate global climate typically feature resolution too coarse to reproduce many smaller-scale processes, which are crucial to determining the regional responses to climate change. A novel approach to downscale climate change scenarios is presented which includes the interactions between the North Atlantic Ocean and the European shelves as well as their impact on the North Atlantic and European climate. The goal of this paper is to introduce the global ocean-regional atmosphere coupling concept and to show the potential benefits of this model system to simulate present-day climate. A global ocean-sea ice-marine biogeochemistry model (MPIOM/HAMOCC) with regionally high horizontal resolution is coupled to an atmospheric regional model (REMO) and global terrestrial hydrology model (HD) via the OASIS coupler. Moreover, results obtained with ROM using NCEP/NCAR reanalysis and ECHAM5/MPIOM CMIP3 historical simulations as boundary conditions are presented and discussed for the North Atlantic and North European region. The validation of all the model components, i.e., ocean, atmosphere, terrestrial hydrology, and ocean biogeochemistry is performed and discussed. The careful and detailed validation of ROM provides evidence that the proposed model system improves the simulation of many aspects of the regional climate, remarkably the ocean, even though some biases persist in other model components, thus leaving potential for future improvement. We conclude that ROM is a powerful tool to estimate possible impacts of climate change on the regional scale.

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

    E-print Network

    Brown, Adrian J; Scargle, Jeffrey D

    2015-01-01

    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...

  8. Evaluating Observation Influence on Regional Water Budgets in Reanalyses

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  9. Influence of 2010 Canadian Forest Fires on Cloud Formation on the Regional Scale

    NASA Astrophysics Data System (ADS)

    Walter, C.; Freitas, S. R.; Kraut, I.; Rieger, D.; Vogel, H.; Vogel, B.

    2014-12-01

    In July 2010 a strong biomass burning event occurred in the North of Saskatchewan, Canada. The fires were well observed by satellites. The changing synoptic situation and the variations in plume height created a complex distribution of the emitted gaseous and particulate matter. The comprehensive regional model system COSMO-ART allows us to study the influence of aerosols on the atmosphere. The formation of new aerosol particles from gaseous precursors is as well accounted as changes in the mixing state of existing aerosol particles. The impact of aerosol particles on cloud microphysics and precipitation is simulated by a two-moment scheme in combination with parameterizations for aerosol activation and ice nucleation. To address emissions from biomass burning, the model system was extended by a plume rise model. It delivers the effective emission height which depends on the current state of the atmosphere and the fire intensity. Datasets based on satellites provide the composition and source strength of numerous chemical tracers. With this framework we are able to gain insight into various effects of aerosols from biomass burning. We found that simulated aerosol optical depth is in very good agreement with AERONET measurements. Temperature at the surface is significantly influenced by adsorbing and scattering particles inside elevated smoke layers. This has further impact on thermal stratification. The high aerosol load inside clouds leads to displaced precipitation patterns. Number and size distributions of cloud droplets are examined for different smoke regimes. It turns out that it depends on the hygroscopicity of available aerosols.

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

    USGS Publications Warehouse

    Hostetler, S.W.; Giorgi, F.

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  12. Atmospheric trace elements over source regions for Chinese dust: concentrations, sources and atmospheric deposition on the Loess plateau

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoye; Arimoto, Richard; An, Zhisheng; Chen, Tuo; Zhang, Guangyu; Zhu, Guanghua; Wang, Xinfu

    The mass-particle size distributions of up to 17 trace elements in aerosol particle samples from dust storm and non-dust storm periods were determined for three sites in or near the source regions of Chinese dust. The mass of particulate material in the atmosphere at the sites is dominated by mineral aerosol particles. An absolute principal component analysis of the non-dust storm elemental data for the loess region allows the estimation of the mass contributions from two coarse-particle classes (soil dust and dust associated with pollutants), and two fine-particle classes (soil dust and anomalously enriched). For most elements (Al, Si, Ca, Fe, Ti, K, S and As), the mass-particle size distributions (MSDs) were approximately log-normal. The mass-median diameters (MMDs) of the soil-derived elements tended to decrease with distance from the desert region and when the dust storms subsided. Total dry deposition velocities were calculated by fitting a log-normal distribution to the aerosol data and calculating deposition rates for 100 particle-size intervals using a two-layer deposition model. The mean dry-deposition rates and fluxes were highest during dust storms over desert regions. In thloess region, the calculated dry deposition velocities of soil derived elements (Al, Si, Ca, Fe and Ti) during non-dust storm periods were from 3.1 to 3.7 cm s -1. From the estimated mass-particles size distributions, the coarser and finer mineral particles were found to benriched with Ca, Fe, Ti and K relative to Al or Si. On a yearly basis, the dry atmospheric input to the Loess Plateau was mainly attributable to normal transport processes, i.e. non-dust storm conditions. Wet deposition fluxes estimated from scavenging ratios indicate that dry deposition dominated the total atmospheric deposition of mineral aerosol. The deposition of aerosol particles associated with coal burning or other anthropogenic sources also was considerable on the Loess Plateau.

  13. Regional source-receptor relationships for atmospheric acidity and acid deposition in California. Final report

    SciTech Connect

    Karamchandani, P.; Pilinis, C.; Shah, J.

    1993-12-01

    The report describes the results of a database management and semi-empirical modeling study that was performed to evaluate regional soure-receptor relationships (SRRs) for atmospheric acidity and acidic deposition in California. The objectives of the study were to quantify the contributions of the various source regions in California to acidic deposition at selected receptors in the state and to estimate the uncertainties in the derived values.

  14. The solar wind and its influence on the atmospheres of moon, Mercury and Venus

    NASA Technical Reports Server (NTRS)

    Hartle, R. E.

    1976-01-01

    The solar wind is expected to have an important influence on the atmospheres of the moon, Mercury and Venus and therefore a brief outline of solar wind theory is presented along with the predicted properties of the wind at the orbits of these planets. Since the atmospheres of the moon and possibly Mercury are formed primarily by solar wind accretion, we present the latest accretion models for these bodies. The expected role the solar wind plays on both the ionization and termination of the ionosphere of Venus is discussed.

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

    E-print Network

    Gohm, Alexander

    and Pielke (1977). The sea breeze model and the cloud/mesoscale model had development histories dating backThe Regional Atmospheric Modeling System (RAMS): Development for Parallel Processing Computer and simulating convective clouds, mesoscale convective systems, cirrus clouds, and precipitating weather systems

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

    E-print Network

    Evans, Jason

    such as Australia. 1. Introduction Carbon dioxide (CO2) directly affects the physiology of plants (Field et al. 1995Contrasting Regional Responses to Increasing Leaf-Level Atmospheric Carbon Dioxide over Australia of stomates to increases in leaf-level carbon dioxide (CO2) under differing conditions of moisture

  17. 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

  18. 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...

  19. Influence of flowing helium gas on plasma plume formation in atmospheric pressure plasma

    SciTech Connect

    Yambe, Kiyoyuki; Konda, Kohmei; Ogura, Kazuo

    2015-05-15

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and a foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. The helium gas flowing out of quartz tube mixes with air, and the flow channel is composed of the regions of flowing helium gas and air. The plasma plume length is equivalent to the reachable distance of flowing helium gas. Although the amount of helium gas on the flow channel increases by increasing the inner diameter of quartz tube at the same gas flow velocity, the plasma plume length peaks at around 8?m/s of gas flow velocity, which is the result that a flow of helium gas is balanced with the amount of gas. The plasma plume is formed at the boundary region where the flow of helium gas is kept to the wall of the air.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  3. Biases of the Arctic Climate in a Regional Ocean-Sea Ice-Atmosphere Coupled Model: An Annual Validation

    NASA Astrophysics Data System (ADS)

    Liu, X.

    2014-12-01

    The Coupling of three model components, WRF/PCE (polar climate extension version of weather research and forecasting model (WRF)), ROMS (regional ocean modeling system), and CICE (community ice code), has been implemented, and the regional atmosphere-ocean-sea ice coupled model named WRF/PCE-ROMS-CICE has been validated against ERA-interim reanalysis data sets for 1989. To better understand the reasons that generate model biases, the WRF/PCE-ROMS-CICE results were compared with those of its components, the WRF/PCE and the ROMS-CICE. There are cold biases in surface air temperature (SAT) over the Arctic Ocean, which contribute to the sea ice concentration (SIC) and sea surface temperature (SST) biases in the results of the WRF/PCE-ROMS-CICE. The cold SAT biases also appear in results of the atmospheric component with a mild temperature in winter and similar temperature in summer. Compared to results from the WRF/PCE, due to influences of different distributions of the SIC and the SST and inclusion of interactions of air-sea-sea ice in the WRF/PCE-ROMS-CICE, the simulated SAT has new features. These influences also lead to apparent differences at higher levels of the atmosphere, which can be thought as responses to biases in the SST and sea ice extent. There are similar atmospheric responses to sea ice biases at 700 and 500 hPa, and the strength of response weakens, with a height in January. The atmospheric responses in July reach up to 200 hPa. There are surplus sea ice extents in the Greenland Sea, the Barents Sea, the Davis Strait and the Chukchi Sea, resulting from the ROMS-CICE in winter and in the Beaufort Sea, the Chukchi Sea, the East Siberian Sea and the Laptev Sea in summer. These differences in the SIC distribution can all be explained by those in the SST distributions. These features in the simulated SST and SIC from ROMS-CICE also appear in the WRF/PCE-ROMS-CICE. It is shown that the performance of the WRF/PCE-ROMS-CICE is determined to a large extent by its components, the WRF/PCE and the ROMS-CICE.

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

    PubMed

    Petrou, Ilias; Dimitriou, Konstantinos; Kassomenos, Pavlos

    2015-10-01

    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. PMID:25605407

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

    NASA Astrophysics Data System (ADS)

    Petrou, Ilias; Dimitriou, Konstantinos; Kassomenos, Pavlos

    2015-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  7. The Angular Momentum Constraint on Climate Sensitivity and Downward Influence in the Middle Atmosphere.

    NASA Astrophysics Data System (ADS)

    Shepherd, Theodore G.; Shaw, Tiffany A.

    2004-12-01

    It is shown that under reasonable assumptions, conservation of angular momentum provides a strong constraint on gravity wave drag feedbacks to radiative perturbations in the middle atmosphere. In the time mean, radiatively induced temperature perturbations above a given altitude z cannot induce changes in zonal mean wind and temperature below z through feedbacks in gravity wave drag alone (assuming an unchanged gravity wave source spectrum). Thus, despite the many uncertainties in the parameterization of gravity wave drag, the role of gravity wave drag in middle-atmosphere climate perturbations may be much more limited than its role in climate itself. This constraint limits the possibilities for downward influence from the mesosphere. In order for a gravity wave drag parameterization to respect the momentum constraint and avoid spurious downward influence, any nonzero parameterized momentum flux at a model lid must be deposited within the model domain, and there must be no zonal mean sponge layer. Examples are provided of how violation of these conditions leads to spurious downward influence. For planetary waves, the momentum constraint does not prohibit downward influence, but it limits the mechanisms by which it can occur: in the time mean, downward influence from a radiative perturbation can only arise through changes in reflection and meridional propagation properties of planetary waves.


  8. Atmospheric influence on space-based observation of high-energy cosmic rays

    NASA Astrophysics Data System (ADS)

    Falk, Stefanie; JEM-EUSO Collaboration

    2015-08-01

    High-energy extensive air showers developing in the Earth's atmosphere emit faint UV light that can be detected from space. The impact of varying atmospheric conditions on light emission and transmission has been studied in detail for the space-borne ultra high-energy cosmic ray observatory JEM-EUSO. By these studies, the importance of atmospheric scattering and reflection from ground on the fraction of Cherenkov light as well as fluorescence light received by JEM-EUSO is pointed out. For any telescope measuring UV light from an altitude higher than 40 km, the attenuating influence of the ozone layer cannot be disregarded. Based upon air shower simulation, quantitative numbers of ozone attenuation will be presented.

  9. Characteristics in the jet region of helium radio-frequency atmospheric-pressure glow discharge with array generators

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Bin; Nie, Qiu-Yue

    2015-09-01

    The two-dimensional spatially extended atmospheric plasma arrays by many parallel radio-frequency glow discharge plasma jets packed densely, represent a feature option of large-scale low-temperature atmospheric plasma technologies with distinct capability of directed delivery of reactive species and good insusceptibility to sample variations. However, it is still a challenge to form plasma jet with large area of uniform active species on a downstream substrate due to the complex interactions between individual jets. This paper proposes to numerically study the strategy and mechanism of control/modulation for the array discharge to produce two-dimensional plasma uniformity in the downstream working area. In this work, a two dimensional fluid model is employed to investigate the characteristics in the jet region of helium radio-frequency atmospheric-pressure glow discharge (RF APGD) with array generators. The influences of upstream discharge characteristics, gas flow and their cooperative effects on the distribution of species densities, gas temperatures and the uniformity of active species in the material treating area is studied, and the essential strategy for the modulation method is acquired. The results will be significant for deep understanding of coupling behaviors of multiple plasma plumes in the RF APGD array and applications of the technology.

  10. Simulating carbon exchange using a regional atmospheric model coupled to an advanced land-surface model

    NASA Astrophysics Data System (ADS)

    Ter Maat, H. W.; Hutjes, R. W. A.

    2008-10-01

    A large scale mismatch exists between our understanding and quantification of ecosystem atmosphere exchange of carbon dioxide at local scale and continental scales. This paper will focus on the carbon exchange on the regional scale to address the following question: What are the main controlling factors determining atmospheric carbon dioxide content at a regional scale? We use the Regional Atmospheric Modelling System (RAMS), coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C), and including also sub models for urban and marine fluxes, which in principle include the main controlling mechanisms and capture the relevant dynamics of the system. To validate the model, observations are used which were taken during an intensive observational campaign in the central Netherlands in summer 2002. These included flux-site observations, vertical profiles at tall towers and spatial fluxes of various variables taken by aircraft. The coupled regional model (RAMS-SWAPS-C) generally does a good job in simulating results close to reality. The validation of the model demonstrates that surface fluxes of heat, water and CO2 are reasonably well simulated. The comparison against aircraft data shows that the regional meteorology is captured by the model. Comparing spatially explicit simulated and observed fluxes we conclude that in general simulated latent heat fluxes are underestimated by the model to the observations which exhibit large standard deviation for all flights. Sensitivity experiments demonstrated the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same test also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.

  11. Improved PPP Ambiguity Resolution Considering the Stochastic Characteristics of Atmospheric Corrections from Regional Networks.

    PubMed

    Li, Yihe; Li, Bofeng; Gao, Yang

    2015-01-01

    With the increased availability of regional reference networks, Precise Point Positioning (PPP) can achieve fast ambiguity resolution (AR) and precise positioning by assimilating the satellite fractional cycle biases (FCBs) and atmospheric corrections derived from these networks. In such processing, the atmospheric corrections are usually treated as deterministic quantities. This is however unrealistic since the estimated atmospheric corrections obtained from the network data are random and furthermore the interpolated corrections diverge from the realistic corrections. This paper is dedicated to the stochastic modelling of atmospheric corrections and analyzing their effects on the PPP AR efficiency. The random errors of the interpolated corrections are processed as two components: one is from the random errors of estimated corrections at reference stations, while the other arises from the atmospheric delay discrepancies between reference stations and users. The interpolated atmospheric corrections are then applied by users as pseudo-observations with the estimated stochastic model. Two data sets are processed to assess the performance of interpolated corrections with the estimated stochastic models. The results show that when the stochastic characteristics of interpolated corrections are properly taken into account, the successful fix rate reaches 93.3% within 5 min for a medium inter-station distance network and 80.6% within 10 min for a long inter-station distance network. PMID:26633400

  12. The Influence of Atmosphere Parameters on the Signal for Remote Sensing Polarimetric Electro-Optical Systems

    NASA Astrophysics Data System (ADS)

    Budak, Vladimir P.; Korkin, Sergey V.

    2009-03-01

    The singularity subtraction on the vectorial modification of spherical harmonics method (VMSH) of the solution of the vectorial radiative transfer equation boundary problem is applied to the problem of influence of atmosphere parameters on the polarimetric system signal. We assume in this model different phase matrices (Mie, Rayleigh, and Henyey-Greenstein), reflecting bottom and particle size distribution. The authors describe the main features of the model and some results of its implementation.

  13. Molecular Radiation of the Upper Atmosphere in the 3-8-micro Spectral Region.

    PubMed

    Markov, M N

    1969-05-01

    The upper atmosphere ir radiation has been investigated by rockets and satellites. The upper atmosphere radiation has a layer structure, its maximum intensity being observed at altitudes of 150 km, 280 km, 430 km, and 500 km. The radiation energy density in the layers reaches 10(-4) erg/cm(3) sec, increasing to 10(-3) erg/cm(3) sec during a magnetic storm. The character of spectral distribution (with maximum in the region of 4.5-8.5 micro) corresponds to apparently NO, OH, and CO. PMID:20072341

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

    E-print Network

    Kachakhidze, M K; Kachakhidze, N K

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    SciTech Connect

    Skinner, Chris B; Ashfaq, Moetasim; Diffenbaugh, Noah

    2011-01-01

    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.

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

    E-print Network

    Alexander Bolonkin

    2008-05-11

    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.

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

    PubMed Central

    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

    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

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

    PubMed

    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

    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

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

    PubMed

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

    2014-10-01

    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

  1. A review of atmospheric transmission information in the optical and microwave spectral regions

    NASA Astrophysics Data System (ADS)

    Downs, A. R.

    1976-12-01

    Much information has been generated over a long period of time on the transmission through the atmosphere of radiation of various wavelengths. This report represents an attempt to consolidate some of the available information into a single report. This report addresses five wavelengths each in the optical and microwave regions. Attenuation mechanisms considered are Rayleigh and Mie scattering and absorption by both water vapor and water drops. Atmospheres characterized by visibilities between 0.1 km (fog) and 325 km (clear air) and by rainfalls at rates up to 64 mm/hr are considered. Pertinent formulations and tables are provided to assist in calculating attenuation coefficients characteristic of a wide variety of atmospheres, and the adequacy of the data bases upon which such calculations rest is assessed. A limited amount of information is also provided on the attenuation characteristics of smoke and dust.

  2. The influence of atmospheric circulation on the type of precipitation (Kraków, southern Poland)

    NASA Astrophysics Data System (ADS)

    Twardosz, Robert; Nied?wied?, Tadeusz; ?upikasza, Ewa

    2011-05-01

    The paper discusses the impact of atmospheric circulation on the occurrence of various types of precipitation. A 146-year-long precipitation record from Kraków spanning the period 1863-2008 was used alongside a calendar prepared by Nied?wied? (1981, 2009) describing circulation types covering the period 1873-2008 and air masses and atmospheric fronts covering the period 1951-2008 in southern Poland. The influence of atmospheric circulation on precipitation was measured using the frequency, conditional probability and average daily totals of precipitation. Circulation types, air masses and atmospheric fronts exerted influences on precipitation as a result of the seasonal variations of the thermal and moisture properties of air masses. The impact is best expressed by circulation types as these combine the aspect of cyclonicity/anticyclonicity with that of the direction of air advection, the two elements which determine the physical properties of the air. On average, liquid precipitation prevailed in all circulation types, except the Ea type in which snowfall dominated over liquid precipitation. Depending on the season, one of the three types of circulation, Wa, Wc and Bc, were shown to coincide with the greatest amount of liquid and thunderstorm precipitation. There was no single dominant circulation type for mixed precipitation or snowfall. In summer, the circulation types Nc, NEc, Cc and Bc were the most favourable to liquid and thunderstorm precipitation in terms of both probability and totals. In winter, snowfall was the most favoured by the Ec type. Frontal precipitation was twice as likely to occur as air mass precipitation, with the exception of snowfall which was predominantly an air mass type of precipitation in terms of probability, but its greatest totals were recorded on atmospheric fronts.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  4. Atmospheric water balance over oceanic regions as estimated from satellite, merged, and reanalysis data

    NASA Astrophysics Data System (ADS)

    Park, Hyo-Jin; Shin, Dong-Bin; Yoo, Jung-Moon

    2013-05-01

    The column integrated atmospheric water balance over the ocean was examined using satellite-based and merged data sets for the period from 2000 to 2005. The data sets for the components of the atmospheric water balance include evaporation from the HOAPS, GSSTF, and OAFlux and precipitation from the HOAPS, CMAP, and GPCP. The water vapor tendency was derived from water vapor data of HOAPS. The product for water vapor flux convergence estimated using satellite observation data was used. The atmospheric balance components from the MERRA reanalysis data were also examined. Residuals of the atmospheric water balance equation were estimated using nine possible combinations of the data sets over the ocean between 60°N and 60°S. The results showed that there was considerable disagreement in the residual intensities and distributions from the different combinations of the data sets. In particular, the residuals in the estimations of the satellite-based atmospheric budget appear to be large over the oceanic areas with heavy precipitation such as the intertropical convergence zone, South Pacific convergence zone, and monsoon regions. The lack of closure of the atmospheric water cycle may be attributed to the uncertainties in the data sets and approximations in the atmospheric water balance equation. Meanwhile, the anomalies of the residuals from the nine combinations of the data sets are in good agreement with their variability patterns. These results suggest that significant consideration is needed when applying the data sets of water budget components to quantitative water budget studies, while climate variability analysis based on the residuals may produce similar results.

  5. On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model

    NASA Astrophysics Data System (ADS)

    Berg, Peter; Döscher, Ralf; Koenigk, Torben

    2015-08-01

    Impacts of spectral nudging on simulations of Arctic climate in coupled simulations have been investigated in a set of simulations with a regional climate model (RCM). The dominantly circumpolar circulation in the Arctic lead to weak constraints on the lateral boundary conditions (LBCs) for the RCM, which causes large internal variability with strong deviations from the driving model. When coupled to an ocean and sea ice model, this results in sea ice concentrations that deviate from the observed spatial distribution. Here, a method of spectral nudging is applied to the atmospheric model RCA4 in order to assess the potentials for improving results for the sea ice concentrations when coupled to the RCO ocean-sea ice model. The spectral nudging applied to reanalysis driven simulations significantly improves the generated sea ice regarding its temporal evolution, extent and inter-annual trends, compared to simulations with standard LBC nesting. The method is furthermore evaluated with driving data from two CMIP5 GCM simulations for current and future conditions. The GCM biases are similar to the RCA4 biases with ERA-Interim, however, the spectral nudging still improves the surface winds enough to show improvements in the simulated sea ice. For both GCM downscalings, the spectrally nudged version retains a larger sea ice extent in September further into the future. Depending on the sea ice formulation in the GCM, the temporal evolution of the regional sea ice model can deviate strongly.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

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

    SciTech Connect

    Heng, Kevin

    2012-03-20

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

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

    NASA Astrophysics Data System (ADS)

    Thayer, Jeffrey; Hsu, Vicki

    2015-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  12. Regional and Local Carbon Flux Information from a Continuous Atmospheric CO2 Network in the Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Heck, S. L.; Stephens, B.; Watt, A.

    2007-12-01

    We will present preliminary carbon flux estimates from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON). In order to improve our understanding of regional carbon fluxes in the Rocky Mountain West, we have developed and deployed autonomous, inexpensive, and robust CO2 analyzers (AIRCOA) at five sites throughout Colorado and Utah, and plan additional deployments on the Navajo Reservation, Arizona in September 2007 and atop Mount Kenya, Africa in November 2007. We have used a one- dimensional CO2 budget equation, following Bakwin et al. (2004), to estimate regional monthly-mean fluxes from our continuous CO2 concentrations. These comparisons between our measurements and estimates of free- tropospheric background concentrations reveal regional-scale CO2 flux signals that are generally consistent with one another across the Rocky RACCOON sites. We will compare the timing and magnitude of these estimates with expectations from local-scale eddy-correlation flux measurements and bottom-up ecosystem models. We will also interpret the differences in monthly-mean flux signals between our sites in terms of their varying upwind areas of influence and inferred regional variations in CO2 fluxes. Our measurements will be included in future CarbonTracker assimilation runs and other planned model-data fusion efforts. However, questions still exist concerning the ability of these models to accurately represent the various influences on CO2 concentrations in continental boundary layers, and at mountaintop sites in particular. We will present an analysis of the diurnal cycles in CO2 concentration and CO2 variability at our sites, and compare these to various model estimates. Several of our sites near major population centers reflect the influence of industrial CO2 sources in afternoon upslope flows, with CO2 concentration increasing and variable in the mid to late afternoon. Other more remote sites show more consistent and decreasing CO2 concentrations throughout the afternoon. These measurements provide insight as to when and under what conditions mountaintop CO2 signals are regionally representative, as well as first-order constraints on boundary-layer heights and flux rates for use in evaluating model fidelity. Because of coarse representation of topography and boundary-layer mixing biases, forward model CO2 diurnal cycles can be 180 degrees out of phase with respect to assimilated mountaintop CO2 observations if care is not taken in the choice of model level used.

  13. Regional and global impacts of Criegee intermediates on atmospheric sulphuric acid concentrations and first steps of aerosol formation.

    PubMed

    Percival, Carl J; Welz, Oliver; Eskola, Arkke J; Savee, John D; Osborn, David L; Topping, David O; Lowe, Douglas; Utembe, Steven R; Bacak, Asan; McFiggans, Gordon; Cooke, Michael C; Xiao, Ping; Archibald, Alexander T; Jenkin, Michael E; Derwent, Richard G; Riipinen, Ilona; Mok, Daniel W K; Lee, Edmond P F; Dyke, John M; Taatjes, Craig A; Shallcross, Dudley E

    2013-01-01

    Carbonyl oxides ("Criegee intermediates"), formed in the ozonolysis of alkenes, are key species in tropospheric oxidation of organic molecules and their decomposition provides a non-photolytic source of OH in the atmosphere (Johnson and Marston, Chem. Soc. Rev., 2008, 37, 699, Harrison et al, Sci, Total Environ., 2006, 360, 5, Gäb et al., Nature, 1985, 316, 535, ref. 1-3). Recently it was shown that small Criegee intermediates, C.I.'s, react far more rapidly with SO2 than typically represented in tropospheric models, (Welz, Science, 2012, 335, 204, ref. 4) which suggested that carbonyl oxides could have a substantial influence on the atmospheric oxidation of SO2. Oxidation of 502 is the main atmospheric source of sulphuric acid (H2SO4), which is a critical contributor to aerosol formation, although questions remain about the fundamental nucleation mechanism (Sipilä et al., Science, 2010, 327, 1243, Metzger et al., Proc. Natl. Acad. Sci. U. S. A., 2010 107, 6646, Kirkby et al., Nature, 2011, 476, 429, ref. 5-7). Non-absorbing atmospheric aerosols, by scattering incoming solar radiation and acting as cloud condensation nuclei, have a cooling effect on climate (Intergovernmental Panel on Climate Change (IPCC), Climate Change 2007: The Physical Science Basis, Cambridge University Press, 2007, ref. 8). Here we explore the effect of the Criegees on atmospheric chemistry, and demonstrate that ozonolysis of alkenes via the reaction of Criegee intermediates potentially has a large impact on atmospheric sulphuric acid concentrations and consequently the first steps in aerosol production. Reactions of Criegee intermediates with SO2 will compete with and in places dominate over the reaction of OH with SO2 (the only other known gas-phase source of H2SO4) in many areas of the Earth's surface. In the case that the products of Criegee intermediate reactions predominantly result in H2SO4 formation, modelled particle nucleation rates can be substantially increased by the improved experimentally obtained estimates of the rate coefficients of Criegee intermediate reactions. Using both regional and global scale modelling, we show that this enhancement is likely to be highly variable spatially with local hot-spots in e.g. urban outflows. This conclusion is however contingent on a number of remaining uncertainties in Criegee intermediate chemistry. PMID:24600996

  14. Multiyear measurements of the oceanic and atmospheric boundary layers at the Brazil-Malvinas confluence region

    NASA Astrophysics Data System (ADS)

    Pezzi, Luciano Ponzi; de Souza, Ronald Buss; Acevedo, OtáVio; Wainer, Ilana; Mata, Mauricio M.; Garcia, Carlos A. E.; de Camargo, Ricardo

    2009-10-01

    This study analyzes and discusses data taken from oceanic and atmospheric measurements performed simultaneously at the Brazil-Malvinas Confluence (BMC) region in the southwestern Atlantic Ocean. This area is one of the most dynamical frontal regions of the world ocean. Data were collected during four research cruises in the region once a year in consecutive years between 2004 and 2007. Very few studies have addressed the importance of studying the air-sea coupling at the BMC region. Lateral temperature gradients at the study region were as high as 0.3°C km-1 at the surface and subsurface. In the oceanic boundary layer, the vertical temperature gradient reached 0.08°C m-1 at 500 m depth. Our results show that the marine atmospheric boundary layer (MABL) at the BMC region is modulated by the strong sea surface temperature (SST) gradients present at the sea surface. The mean MABL structure is thicker over the warmside of the BMC where Brazil Current (BC) waters predominate. The opposite occurs over the coldside of the confluence where waters from the Malvinas (Falkland) Current (MC) are found. The warmside of the confluence presented systematically higher MABL top height compared to the coldside. This type of modulation at the synoptic scale is consistent to what happens in other frontal regions of the world ocean, where the MABL adjusts itself to modifications along the SST gradients. Over warm waters at the BMC region, the MABL static instability and turbulence were increased while winds at the lower portion of the MABL were strong. Over the coldside of the BC/MC front an opposite behavior is found: the MABL is thinner and more stable. Our results suggest that the sea-level pressure (SLP) was also modulated locally, together with static stability vertical mixing mechanism, by the surface condition during all cruises. SST gradients at the BMC region modulate the synoptic atmospheric pressure gradient. Postfrontal and prefrontal conditions produce opposite thermal advections in the MABL that lead to different pressure intensification patterns across the confluence.

  15. Regional Sea Level Variations from GRACE, InSAR and a Regional Atmospheric Climate Model Output Products

    NASA Astrophysics Data System (ADS)

    Hsu, C. W.; Velicogna, I.; Rignot, E. J.; Wahr, J. M.

    2014-12-01

    We generate static regional sea level variations (sea level fingerprints, SLF) from ice sheets, glaciers and land hydrology using 10 years of monthly NASA/DLR GRACE satellite data and 40 years of ice sheet mass balance from the mass budget method (surface mass balance from a regional atmospheric climate model minus ice discharge along the periphery). We evaluate the impact of the spatial distribution in ice sheet mass balance on the inferred regional sea level pattern. Based on the results, we derive requirements on the spatial scale of mass loss needed to resolve the regional pattern of sea level change. In the calculation of the water and ice mass changes over land, we also need to restore the amplitude of the GRACE signal before calculating the regional sea level pattern. Here, we describe an improved scaling factor method that comprises both a seasonal and a long-term component. We discuss the impact of these components on the retrieved regional sea level pattern. Using the SLF, we identify the sources of observed sea level variations. We show that the cumulative SLF describe a large portion of the trend and annual amplitude of the observed sea level variations at both the global and basin scales. When comparing the cumulative SLF with observations of sea level change from steric corrected altimetry, we find an excellent agreement at the global and basin scales. We discuss differences in sea level pattern between the last decade and the prior 40 years. This work was conducted at the University of California Irvine and at Caltech's Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

  16. Precipitation recycling in West Africa - regional modeling, evaporation tagging and atmospheric water budget analysis

    NASA Astrophysics Data System (ADS)

    Arnault, Joel; Kunstmann, Harald; Knoche, Hans-Richard

    2015-04-01

    Many numerical studies have shown that the West African monsoon is highly sensitive to the state of the land surface. It is however questionable to which extend a local change of land surface properties would affect the local climate, especially with respect to precipitation. This issue is traditionally addressed with the concept of precipitation recycling, defined as the contribution of local surface evaporation to local precipitation. For this study the West African monsoon has been simulated with the Weather Research and Forecasting (WRF) model using explicit convection, for the domain (1°S-21°N, 18°W-14°E) at a spatial resolution of 10 km, for the period January-October 2013, and using ERA-Interim reanalyses as driving data. This WRF configuration has been selected for its ability to simulate monthly precipitation amounts and daily histograms close to TRMM (Tropical Rainfall Measuring Mission) data. In order to investigate precipitation recycling in this WRF simulation, surface evaporation tagging has been implemented in the WRF source code as well as the budget of total and tagged atmospheric water. Surface evaporation tagging consists in duplicating all water species and the respective prognostic equations in the source code. Then, tagged water species are set to zero at the lateral boundaries of the simulated domain (no inflow of tagged water vapor), and tagged surface evaporation is considered only in a specified region. All the source terms of the prognostic equations of total and tagged water species are finally saved in the outputs for the budget analysis. This allows quantifying the respective contribution of total and tagged atmospheric water to atmospheric precipitation processes. The WRF simulation with surface evaporation tagging and budgets has been conducted two times, first with a 100 km2 tagged region (11-12°N, 1-2°W), and second with a 1000 km2 tagged region (7-16°N, 6°W -3°E). In this presentation we will investigate hydro-atmospheric processes involved in the atmospheric branch of the water cycle in West Africa, based on our WRF simulation. We will particularly focus on the respective contribution of local and remote water vapor to atmospheric processes involved in local precipitation, and compare the results at the 100 and 1000 km2 scales. The potential impact of local land use change on local precipitation will finally be discussed based on this quantitative analysis.

  17. The influence of land-atmosphere interactions on variability of the North American Monsoon

    NASA Technical Reports Server (NTRS)

    Small, Eric; Lakshmi, Venkat

    2005-01-01

    Our project focused on the influence of land-atmosphere interactions on variability of North American Monsoon System (NAMS) precipitation is summarized in seven published manuscripts (listed below). Three of these manuscripts (Matsui et al. 2003; Matsui et al. 2005; Small and Kurc 2003) were completed solely with support from this NASA project. The remaining four were completed with additional support from NOAA. Our primary results are summarized: 1) Test of Rocky Mountains snowcover-NAMS rainfall hypothesis. Testing radiation and convective precipitation parameterization in MM5. Analysis of soil moisture-radiation feedbacks in semiarid environments from field observations and modeling.

  18. Influence of atmospheric turbulence on OAM-based FSO system with use of realistic link model

    NASA Astrophysics Data System (ADS)

    Li, Ming; Yu, Zhongyuan; Cvijetic, Milorad

    2016-04-01

    We study the influence of atmospheric turbulence on OAM-based free-space optical (FSO) communication by using the Pump turbulence spectrum model which accurately characterizes the realistic FSO link. A comprehensive comparison is made between the Pump and Kolmogorov spectrum models with respect to the turbulence impact. The calculated results show that obtained turbulence-induced crosstalk is lower, which means that a higher channel capacity is projected when the realistic Pump spectrum is used instead of the Kolmogorov spectrum. We believe that our results prove that performance of practical OAM-based FSO is better than one predicted by using the original Kolmogorov turbulence model.

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

    PubMed

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

    2014-08-15

    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

  20. Atmospheric Profiling using GPS Radio Occultation over the Australian and Antarctic regions

    NASA Astrophysics Data System (ADS)

    Norman, R.; Le Marshall, J.; Carter, B. A.; Kirchengast, G.; Alexander, S.; Wang, C. S.; Zhang, K.

    2014-12-01

    The space-based Global Positioning System (GPS) Radio Occultation (RO) technique is ideal for sounding the Earth's atmosphere. The GPS RO technique uses GPS receiver's on-board Low Earth Orbit (LEO) satellites to measure the received radio signals from GPS satellites. Atmospheric parameter profiles of electron density, temperature, pressure and water vapor can then be obtained using well defined and robust retrieval processes. In this study atmospheric parameter profiles were retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) GPS RO measurements for the years 2007 to 2013 over Australia, Antarctica and their surrounding oceans. The yearly and bi-monthly tropopause height and temperature and climatic trends are investigated and co-located GPS RO and radiosonde atmospheric profiles are compared. Forecast skill scores with and without GPS RO data over the Australian and Antarctic regions are also assessed. Finally, a 3-D ray tracing technique was developed to investigate and improve the GPS RO technique. Simulated results from a tropospheric storm event on GPS RO signal propagation are investigated.

  1. An Empirical Study of Atmospheric Correction Procedures for Regional Infrasound Amplitudes with Ground Truth.

    NASA Astrophysics Data System (ADS)

    Howard, J. E.

    2014-12-01

    This study focusses on improving methods of accounting for atmospheric effects on infrasound amplitudes observed on arrays at regional distances in the southwestern United States. Recordings at ranges of 150 to nearly 300 km from a repeating ground truth source of small HE explosions are used. The explosions range in actual weight from approximately 2000-4000 lbs. and are detonated year-round which provides signals for a wide range of atmospheric conditions. Three methods of correcting the observed amplitudes for atmospheric effects are investigated with the data set. The first corrects amplitudes for upper stratospheric wind as developed by Mutschlecner and Whitaker (1999) and uses the average wind speed between 45-55 km altitudes in the direction of propagation to derive an empirical correction formula. This approach was developed using large chemical and nuclear explosions and is tested with the smaller explosions for which shorter wavelengths cause the energy to be scattered by the smaller scale structure of the atmosphere. The second approach isa semi-empirical method using ray tracing to determine wind speed at ray turning heights where the wind estimates replace the wind values in the existing formula. Finally, parabolic equation (PE) modeling is used to predict the amplitudes at the arrays at 1 Hz. The PE amplitudes are compared to the observed amplitudes with a narrow band filter centered at 1 Hz. An analysis is performed of the conditions under which the empirical and semi-empirical methods fail and full wave methods must be used.

  2. Model estimates of global and regional atmospheric methane emissions of wetland ecosystems

    NASA Astrophysics Data System (ADS)

    Denisov, S. N.; Eliseev, A. V.; Mokhov, I. I.; Arzhanov, M. M.

    2015-09-01

    Estimates of the changes of atmospheric methane emissions from wetland ecosystems for different regions and the Earth as a whole are performed. The new version of the model of methane emissions from soil in a global climate model of intermediate complexity developed at the A.M. Obukhov Institute of atmospheric physics is used. Numerical experiments in accordance with the conditions of WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project) have been performed. The model is capable of realistically reproducing global and regional characteristics of methane emissions. The general trend of increases in methane flows from wetland ecosystems into the atmosphere due to global warming is noted. According to the results of calculations, the global natural methane emissions from wetlands have increased in the 20th century by 9 MtCH4/year. The sensitivity of global methane emissions to changes in global near-surface temperature over the land was estimated to be equal to 16 MtCH4/year/K (approximately 10%/K). With continuing warming, we can expect a significant increase in methane emissions, primarily from the high latitudes of the northern hemisphere.

  3. The puzzling chemical composition of GJ 436B'S atmosphere: Influence of tidal heating on the chemistry

    SciTech Connect

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

    2014-02-01

    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/CH{sub 4} 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 CO{sub 2}/H{sub 2}O abundance ratio increases dramatically with metallicity, and takes values between 10{sup –5}-10{sup –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/CH{sub 4} abundance ratios and warm temperatures in the dayside atmosphere are favored.

  4. Advanced Modeling Techniques to Study Anthropogenic Influences on Atmospheric Chemical Budgets

    NASA Technical Reports Server (NTRS)

    Mathur, Rohit

    1997-01-01

    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.

  5. Correlating CCM upper atmosphere parameters to surface observations for regional climate change predictions

    SciTech Connect

    Li, Xiangshang; Sailor, D.J.

    1997-11-01

    This paper explores the use of statistical downscaling of General Circulation Model (GCM) results for the purpose of regional climate change analysis. The strong correlation between surface observations and GCM upper air predictions is used in an approach very similar to the Model Output Statistics approach used in numerical weather prediction. The primary assumption in this analysis is that the statistical relationships remain unchanged under conditions of climatic change. These relations are applied to GCM upper atmosphere predictions for future (2*CO{sub 2}) climate predictions. The result is a set of regional climate change predictions conceptually valid at the scale of cities. The downscaling for specific cities within a GCM grid cell reveals some of the anticipated variability within the grid cell. In addition, multiple linear regression analysis may indicate warming that is significantly higher or lower for a particular region than the raw data from the GCM runs. 3 refs., 3 figs., 2 tabs.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  7. Stellar Winds and High-Energy Radiation: Evolution and influences on planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Johnstone, C.; Tu, L.; Güdel, M.; Lüftinger, T.; Lammer, H.; Kislyakova, K.; Fichtinger, B.

    2015-10-01

    As part of the Austrian research network "Pathways to Habitability: From Disks to Active Stars, Planets and Life" (path.univie.ac.at), we study the evolution of stellar output (e.g. winds, high-energy radiation) over the lifetimes of solar-like stars and the influence of stellar output on the development of habitable planetary environments. We have developed a coupled stellar rotation-wind-radiation model that describes the long term evolution of stellar output over the course of a star's life. We show that the initial rotation rate of a star can significantly influence the evolution of winds and high-energy radiation and therefore the development of planetary atmospheres.

  8. Influence of the Spray Angle on the Characteristics of Atmospheric Plasma Sprayed Hard Material Based Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Vogli, Evelina; Krebs, Benjamin

    2008-12-01

    This paper presents an investigation of the influence of the spray angle on thermally sprayed coatings. Spray beads were manufactured with different spray angles between 90 and 20° by means of atmospheric plasma spraying (APS) on heat-treated mild steel (1.0503). WC-12Co and Cr3C2-10(Ni20Cr) powders were employed as feedstock materials. Every spray bead was characterized by a Gaussian fit. This opens the opportunity to analyze the influence of the spray angle on coating properties. Furthermore, metallographic studies of the surface roughness, porosity, hardness, and morphology were carried out and the deposition efficiency as well as the tensile strength was measured. The thermally sprayed coatings show a clear dependence on the spray angle. A decrease in spray angle changes the thickness, width, and form of the spray beads. The coatings become rougher and their quality decreases.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  10. The influence of the Extreme Ultraviolet spectral energy distribution on the structure and composition of the upper atmosphere of exoplanets

    E-print Network

    Guo, J H

    2015-01-01

    By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distribution (SED), we tested the influences of stellar EUV SEDs on the physical and chemical properties of the escaping atmosphere. We apply our model to study four exoplanets, HD\\,189733b, HD\\,209458b, GJ \\,436b, and Kepler-11b. We found that the total mass loss rates of an exoplanet, which are determined mainly by the integrated fluxes, are moderately affected by the profiles of the EUV SED, but the composition and species distributions in the atmosphere can be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape parameter ($\\lambda$), the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. The effect of photoionization of H is prominent when the EUV SED is dominated by the low-energy spectral region (400-900${\\AA}$), which pushes the transition of H/H$^{+}$ to low al...

  11. How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006

    E-print Network

    How natural and anthropogenic influences alter global and regional surface temperatures: 1889 and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006, Geophys. Res. Lett., 35 as greenhouse gas concentrations increased, fueling debate about the reality of anthropogenic global warming. [3

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

    SciTech Connect

    Moritzer, E. Leister, C.

    2014-05-15

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Atmospheric deposition of trace elements recorded in snow from the Mt. Nyainqêntanglha region, southern Tibetan Plateau.

    PubMed

    Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Chen, Pengfei; Zhang, Guoshuai; Tripathee, Lekhendra

    2013-08-01

    In May 2009, snowpit samples were collected from a high-elevation glacier in the Mt. Nyainqêntanglha region on the southern Tibetan Plateau. A set of elements (Al, V, Cr, Mn, Co, Ni, Cu, Zn, Cd, Hg and Pb) was analyzed to investigate the concentrations, deposition fluxes of trace elements, and the relative contributions from anthropogenic and natural sources deposited on the southern Tibetan Plateau. Concentrations of most of the trace elements in snowpit samples from the Zhadang glacier are significantly lower than those examined from central Asia (e.g., eastern Tien Shan), with higher concentrations during the non-monsoon season than during the monsoon season. The elements of Al, V, Cr, Mn, Co, and Ni display low crustal enrichment factors (EFs), while Cu, Zn, Cd, Hg, and Pb show high EF values in the snow samples, suggesting anthropogenic inputs are potentially important for these elements in the remote, high-elevation atmosphere on the southern Tibetan Plateau. Together with the fact that the concentration levels of such elements in the Mt. Nyainqêntanglha region are significantly higher than those observed on the south edge of the Tibetan Plateau, our results suggest that the high-elevation atmosphere on the southern Tibetan Plateau may be more sensitive to variations in the anthropogenic emissions of atmospheric trace elements than that in the central Himalayas. Moreover, the major difference between deposition fluxes estimated in our snow samples and those recently measured at Nam Co Station for elements such as Cr and Cu may suggest that atmospheric deposition of some of trace elements reconstructed from snowpits and ice cores could be grossly underestimated on the Tibetan Plateau. PMID:23535470

  15. Regional-scale atmospheric simulations of chemical layering over the western North Atlantic

    SciTech Connect

    Fast, J.D.; Berkowitz, C.M.

    1996-12-31

    Aircraft measurements of hydrocarbons, ozone, and meteorological parameters were taken over Yarmouth, Nova Scotia between August 8 and September 7, 1993 as part of the 1993 North Atlantic Regional Experiment (NARE). A coupled mesoscale-dispersion modeling system is used to define the source regions, quantify the plume age, and determine extent of mixing associated with the aircraft trace gas chemistry observations. The mesoscale model employed in this study is the Colorado State University Regional Atmospheric Modeling System (RAMS) in which the domain encompasses much of the western North Atlantic. The mesoscale model is run for a fifteen-day period with four-dimensional data assimilation to obtain the synoptic and mesoscale circulations during a portion of the NARE study. The wind, temperature, and turbulence fields from the mesoscale model are used to drive a Lagrangian particle dispersion model (LPDM) to simulate plume transport and diffusion. Forward and back trajectories are also computed by LPDM to help determine the atmospheric mechanisms responsible for the observed ozone profiles.

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

    EPA Science Inventory

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

  17. Mesoscale circulations and atmospheric CO2 variations in the Tapajós Region, Pará, Brazil

    NASA Astrophysics Data System (ADS)

    Lu, Lixin; Denning, A. Scott; da Silva-Dias, Maria Assuncao; da Silva-Dias, Pedro; Longo, Marcos; Freitas, Saulo R.; Saatchi, Sassan

    2005-11-01

    We have investigated mesoscale circulations and atmospheric CO2 variations over a heterogeneous landscape of forests, pastures, and large rivers during the Santarém Mesoscale Campaign (SMC) of August 2001. The atmospheric CO2 concentration variations were simulated using the Colorado State University Regional Atmospheric Modeling System with four nested grids that included a 1-km finest grid centered on the Tapajós National Forest. Surface CO2 fluxes were prescribed using idealized diurnal cycles over forest and pasture that derived from flux tower observations; while surface water CO2 efflux was prescribed using a value suggested by in situ measurements in the Amazon region. Our simulation ran from 1 August through 15 August 2001, which was concurrent with the SMC. Evaluation against flux tower observations and Belterra meteorological tower measurements showed that the model captured the observed 2-m temperatures and 10-m winds reasonably well. At 57 m the model reproduced the daytime CO2 concentration better than the nighttime concentration but missed the observed early morning CO2 maxima, in part because of the difficulties of simulating stable nocturnal boundary conditions and subgrid-scale intracanopy processes. The results also suggested that the topography, the differences in roughness length between water and land, the "T" shape juxtaposition of Amazon and Tapajós Rivers, and the resulting horizontal and vertical wind shears all facilitated the generation of local mesoscale circulations. Possible mechanisms producing a low-level convergence (LLC) line near the east bank of the Tapajós River were explored. Under strong trade wind conditions, mechanical forcing is more important than thermal forcing in LLC formation. Persistent clouds near the east side of the Tapajós River may have a significant impact on observed ecosystem carbon flux and should be taken into account if tower fluxes are to be generalized to a larger region.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  19. On the atmospheric dynamical responses to land-use change in East Asian monsoon region

    NASA Astrophysics Data System (ADS)

    Zhang, Huqiang; Gao, Xuejie

    2009-08-01

    This study aims at (1) exploring dominant atmospheric dynamical processes which are responsible for climate model-simulated land-use impacts on Asian monsoon; and (2) assessing uncertainty in such model simulations due to their skills in simulating detailed monsoon circulations in the region. Firstly, results from a series of the Australian Bureau of Meteorology Research Centre (BMRC) global model simulations of land-use vegetation changes (LUC) in China are analysed. The model showed consistent signals of changes in atmospheric low-level vertical profile and regional circulations responding to LUC. In northern winter, the model-simulated rainfall reduction and surface cooling are associated with an enhanced southward penetration of dry and cold air mass, which impedes warm and humid air reaching the region for generating cold-front rainfall. In its summer, an enhanced cyclonic circulation responding to LUC further blocks the northeast penetration of southwestly summer monsoon flow into the region and results in rainfall decreases and a surface warming. Secondly, we have explored uncertainties in the proposed mechanism operating in the global model. By comparing its results with a set of high-resolution regional model simulations using the same vegetation datasets, it reveals similar changes in winter rainfall but opposite features in summer rainfall responses. In the global model, there is a cyclonic low-level circulation pattern over the South China Sea and adjacent region, an unsatisfactory feature commonly seen in other global climate models. With the reduction in surface roughness following LUC, such a deficiency becomes more prominent which further results in a weakened south/southwestly summer monsoon flow and rainfall reduction. In contrast, in the regional model, its southwestly summer monsoon flow is further enhanced due to the same process as reduced surface roughness. The enhanced monsoon flow further pushes the East Asian monsoon rainfall belt more northward and increases summer rainfall in the Yangtze River region. This study highlights the need for better monsoon simulations in climate models to produce reliable climate change projections in the region.

  20. Influence of meteorological input and wet deposition schemes on atmospheric transport simulations of radionuclides from the Fukushima accident

    NASA Astrophysics Data System (ADS)

    Arnold, Delia; Wotawa, Gerhard; Maurer, Christian; Seibert, Petra

    2013-04-01

    Meteorological data used as input to atmospheric transport models are of decisive importance for the resulting transport and deposition patterns. Dispersion calculations for Cs-137 and Xe-133 released by the Fukushima reactor accidents have been carried out with different global and local meteorological information, and results compared. The different meteorological input data sets are global model output from ECMWF with different horizontal resolutions, down to approximately 0.1 degrees, and GFS with 0.5 deg resolution. They were used to drive the Lagrangian particle dispersion model FLEXPART. A new fix for the wet deposition scheme in FLEXPART was tested in these simulations as well. The dispersion calculations have been compared to gridded Cs-137 deposition data and the few available ambient nuclide concentrations measurements within Japan. For the global-scale transport results, CTBTO IMS radionuclide measurements provided the required evaluation data. The influence of nested higher resolution meteorological data from the near-source region on the long range transport and wet scavenging influence was also studied.

  1. Model atmospheres of irradiated exoplanets: The influence of stellar parameters, metallicity, and the C/O ratio

    E-print Network

    Mollière, Paul; Dullemond, Cornelis Petrus; Henning, Thomas; Mordasini, Christoph

    2015-01-01

    Many parameters constraining the spectral appearance of exoplanets are still poorly understood. We therefore study the properties of irradiated exoplanet atmospheres over a wide parameter range including metallicity, C/O ratio and host spectral type. We calculate a grid of 1-d radiative-convective atmospheres and emission spectra. We perform the calculations with our new Pressure-Temperature Iterator and Spectral Emission Calculator for Planetary Atmospheres (PETIT) code, assuming chemical equilibrium. The atmospheric structures and spectra are made available online. We find that atmospheres of planets with C/O ratios $\\sim$ 1 and $T_{\\rm eff}$ $\\gtrsim$ 1500 K can exhibit inversions due to heating by the alkalis because the main coolants CH$_4$, H$_2$O and HCN are depleted. Therefore, temperature inversions possibly occur without the presence of additional absorbers like TiO and VO. At low temperatures we find that the pressure level of the photosphere strongly influences whether the atmospheric opacity is d...

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

    SciTech Connect

    Randlett, D.L.; Zak, D.R.; Pregitzer, K.S.; Curtis, P.S.

    1996-09-01

    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.

  3. Visual Empirical Region of Influence (VERI) Pattern Recognition Algorithms

    Energy Science and Technology Software Center (ESTSC)

    2002-05-01

    We developed new pattern recognition (PR) algorithms based on a human visual perception model. We named these algorithms Visual Empirical Region of Influence (VERI) algorithms. To compare the new algorithm's effectiveness against othe PR algorithms, we benchmarked their clustering capabilities with a standard set of two-dimensional data that is well known in the PR community. The VERI algorithm succeeded in clustering all the data correctly. No existing algorithm had previously clustered all the pattens inmore »the data set successfully. The commands to execute VERI algorithms are quite difficult to master when executed from a DOS command line. The algorithm requires several parameters to operate correctly. From our own experiences we realized that if we wanted to provide a new data analysis tool to the PR community we would have to provide a new data analysis tool to the PR community we would have to make the tool powerful, yet easy and intuitive to use. That was our motivation for developing graphical user interfaces (GUI's) to the VERI algorithms. We developed GUI's to control the VERI algorithm in a single pass mode and in an optimization mode. We also developed a visualization technique that allows users to graphically animate and visually inspect multi-dimensional data after it has been classified by the VERI algorithms. The visualization technique that allows users to graphically animate and visually inspect multi-dimensional data after it has been classified by the VERI algorithms. The visualization package is integrated into the single pass interface. Both the single pass interface and optimization interface are part of the PR software package we have developed and make available to other users. The single pass mode only finds PR results for the sets of features in the data set that are manually requested by the user. The optimization model uses a brute force method of searching through the cominations of features in a data set for features that produce the best pattern recognition results. With a small number of features in a data set an exact solution can be determined. However, the number of possible combinations increases exponentially with the number of features and an alternate means of finding a solution must be found. We developed and implemented a technique for finding solutions in data sets with both small and large numbers of features. The VERI interface tools were written using the Tcl/Tk GUI programming language, version 8.1. Although the Tcl/Tk packages are designed to run on multiple computer platforms, we have concentrated our efforts to develop a user interface for the ubiquitous DOS environment. The VERI algorithms are compiled, executable programs. The interfaces run the VERI algorithms in Leave-One-Out mode using the Euclidean metric.« less

  4. Coupling atmospheric mercury isotope ratios and meteorology to identify sources of mercury impacting a coastal urban-industrial region near Pensacola, Florida, USA

    NASA Astrophysics Data System (ADS)

    Demers, Jason D.; Sherman, Laura S.; Blum, Joel D.; Marsik, Frank J.; Dvonch, J. Timothy

    2015-10-01

    Identifying the anthropogenic and natural sources of mercury (Hg) emissions contributing to atmospheric mercury on local, regional, and global scales continues to be a grand challenge. The relative importance of various direct anthropogenic emissions of mercury, in addition to natural geologic sources and reemission of previously released and deposited mercury, differs regionally and temporally. In this study, we used local-scale, mesoscale, and synoptic-scale meteorological analysis to couple the isotopic composition of ambient atmospheric mercury with potential sources of mercury contributing to a coastal urban-industrial setting near a coal-fired power plant in Pensacola, Florida, USA. We were able to broadly discern four influences on the isotopic composition of ambient atmospheric mercury impacting this coastal urban-industrial region: (1) local to regional urban-industrial anthropogenic emissions (mean ?202Hg = 0.44 ± 0.05‰, 1SD, n = 3), (2) marine-influenced sources derived from the Gulf of Mexico (mean ?202Hg = 0.77 ± 0.15‰, 1SD, n = 4), (3) continental sources associated with north-northwesterly flows from within the planetary boundary layer (mean ?202Hg = 0.65 ± 0.04‰, 1SD, n = 3), and (4) continental sources associated with north-northeasterly flows at higher altitudes (i.e., 2000 m above ground level; mean ?202Hg = 1.10 ± 0.21‰, 1SD, n = 8). Overall, these data, in conjunction with previous studies, suggest that the background global atmospheric mercury pool is characterized by moderately positive ?202Hg values; that urban-industrial emissions drive the isotopic composition of ambient atmospheric mercury toward lower ?202Hg values; and that air-surface exchange dynamics across vegetation and soils of terrestrial ecosystems drive the isotopic composition of ambient atmospheric mercury toward higher positive ?202Hg values. The data further suggest that mass-independent fractionation (MIF) of both even-mass- and odd-mass-number isotopes, likely generated by photochemical reactions in the atmosphere or during reemission from terrestrial and aquatic ecosystems, can be obscured by mixing with anthropogenic emissions having different MIF signatures.

  5. Investigating the Influence of Atmospheric Changes on the Variability of the North Pacific Using a Fully Coupled GCM

    NASA Astrophysics Data System (ADS)

    Gomez, P.; Poulsen, C. J.; Stott, L. D.

    2004-12-01

    In this study we attempt to investigate whether changes in atmospheric concentrations in ozone and greenhouse gases (GHGs), including CO2, N2O, and methane, have an influence on decadal-scaled oceanic and atmospheric dynamics in the Northeast Pacific. Using a coupled ocean-atmosphere GCM (FOAM1.5) we simulate climatic conditions for the pre-industry and the present day while focusing on the North Pacific. We explore how the ozone hole over the Southern Hemisphere and increased concentrations in GHGs observed in the present day influence the Pacific (Inter)Decadal Oscillation (PDO) and the North Pacific High (NPH), two dominant modes of variability in the North Pacific. In each model we examine the spatial and temporal patterns of the NPH, sea-surface temperatures and salinities (SSTs, SSSs) as well as wind and ocean currents on the order of interannual to interdecadal time scales. We find that within these simulations the influence of the prescribed atmospheric perturbations is small. We observe that the present-day SST and SSS fields of the Northeast Pacific are similar in both model runs as well as sea level pressure. In both simulations the PDO dominates the patterns of variability in the North Pacific and does not appear to change either in character or expression as a result of the atmospheric perturbations. The atmospheric change caused by the rise in GHG concentrations and the decline in ozone is not prominent as a primary influence on the decadal scale variability within the Northeast Pacific.

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

    USGS Publications Warehouse

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

    1998-01-01

    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.

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

    SciTech Connect

    Huo, W. G.; Xu, K.; Sun, B.; Ding, Z. F.

    2012-08-15

    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.

  8. A new approach to the convective parameterization of the regional atmospheric model BRAMS

    NASA Astrophysics Data System (ADS)

    Dos Santos, A. F.; Freitas, S. R.; de Campos Velho, H. F.; Luz, E. F.; Gan, M. A.; de Mattos, J. Z.; Grell, G. A.

    2013-05-01

    The summer characteristics of January 2010 was performed using the atmospheric model Brazilian developments on the Regional Atmospheric Modeling System (BRAMS). The convective parameterization scheme of Grell and Dévényi was used to represent clouds and their interaction with the large scale environment. As a result, the precipitation forecasts can be combined in several ways, generating a numerical representation of precipitation and atmospheric heating and moistening rates. The purpose of this study was to generate a set of weights to compute a best combination of the hypothesis of the convective scheme. It is an inverse problem of parameter estimation and the problem is solved as an optimization problem. To minimize the difference between observed data and forecasted precipitation, the objective function was computed with the quadratic difference between five simulated precipitation fields and observation. The precipitation field estimated by the Tropical Rainfall Measuring Mission satellite was used as observed data. Weights were obtained using the firefly algorithm and the mass fluxes of each closure of the convective scheme were weighted generating a new set of mass fluxes. The results indicated the better skill of the model with the new methodology compared with the old ensemble mean calculation.

  9. Solar influences on spatial patterns of Eurasian winter temperature and atmospheric general circulation anomalies

    NASA Astrophysics Data System (ADS)

    Chen, Haishan; Ma, Hedi; Li, Xing; Sun, Shanlei

    2015-09-01

    Solar influences on spatial patterns of Eurasian winter climate and possible mechanisms are investigated based on a multiple linear regression method and multisource observational and reanalysis data. Robust and significant solar signals are detected in Eurasian surface air temperature (SAT), and strong solar activity evidently warms most area of the continent. The spatial pattern of sea level pressure (SLP) responses to solar activity is similar but not identical to that of the North Atlantic Oscillation (NAO). Compared to the NAO, geographic distribution of solar-induced SLP anomalies shifts eastward, with significantly enhanced influences over northern Eurasia. Relatively weaker solar signals were also found in mid-to-upper troposphere. The spatial pattern of 500 hPa geopotential anomalies resembles a negative Scandinavia teleconnection pattern, and the 200 hPa subtropical jet is weakened, while zonal wind at high latitudes is enhanced due to strong solar activity. The anomalous zonal circulations can be attributed to the "top-down" mechanism. During high solar activity winters, an enhanced stratospheric zonal wind anomaly propagates downward, causing zonal wind anomalies in the troposphere. However, the "bottom-up" mechanisms may provide more reasonable explanations of the distinct solar influences on Eurasian climate. Solar-induced strong warm advection in lower atmosphere tends to increase SAT but decrease SLP, resulting in enhanced solar influences over northern Eurasia. Meanwhile, change in the land-ocean thermal contrast (LOTC) could also amplify the circulation anomaly. Inhomogeneous surface heating caused by anomalous solar activity modifies LOTC, which probably enhances the solar-induced circulation patterns. Such a positive feedback may potentially strengthen the solar influences.

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

    SciTech Connect

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

    1997-11-01

    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.

  11. Atmospheric wave-induced instability in the nighttime E-region.

    NASA Technical Reports Server (NTRS)

    Beer, T.; Moorcroft, D. R.

    1972-01-01

    Examination of the perturbed continuity equation when the perturbations are the result of an internal atmospheric gravity wave in the E region. The transient response of the ionization is interpreted as the gradient instability and the values of the vertical and horizontal wave numbers that will induce it are plotted for various heights. Only in the presence of westward directed electric fields, which are believed to occur only at night, will the gravity waves induce the gradient instability. Approximate analytic expressions are obtained for the permitted wave numbers as well as for the instability growth times. In the course of this analysis it is shown that in the D region all irregularities, even those that are field-aligned, will tend to move with the ion velocity.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

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

    SciTech Connect

    Buckley, R.

    2001-06-27

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    SciTech Connect

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

    1994-02-01

    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.

  18. Determination of Stellar Atmospheric Parameters from the Near-IR Region

    NASA Astrophysics Data System (ADS)

    Molina, R.; Stock, J.

    2004-10-01

    A sample of 211 giant stars with spectral types K and M has been analyzed, for which pseudo-equivalent widths were measured and stellar atmospheric parameters were previously identified. The spectra of these stars have been taken from a stellar library observed with the Coudé telescope at the Kitt Peak National Observatory, with a resolution of ˜ r Aand covering a spectral region of ?? 3460-9460 Å set of first and second order polynomials is applied, which involves one, two, or three independent variables and allows us to estimate the precision in the effective temperature T[eff], the surface gravity, logg and the metallicity [Fe/H] in terms of the pseudo-equivalent widths of seven absorption features in the near IR regions ?? 5400-9500 Å. The results obtained from linear fittings with three independent variables to the three fundamental atmospheric parameters attain residual averages of (149Â+/-15), (0.26Â+/-0,02), (0.12Â+/-0.02), while the quadratic fittings attain residual averages of (146Â+/-16), (0.25Â+/-0.02), (0.12Â+/-0.02), respectively. It is observed from both results that using higher order polynomials does not improve the residual averages with respect to those obtained from linear fittings. The procedure performed in this work follows the Stock & Stock method (1999).

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  20. Distribution of atmospheric sulphur species over various wetland regions in the southeastern U.S.A.

    NASA Astrophysics Data System (ADS)

    Berresheim, Harald

    Atmospheric dimethylsulphide (DMS), sulphur dioxide (SO 2), aerosol non-seasalt sulphate (nss-SO 4 and methanesulphonate (MSA) were measured periodically at Sapelo Island, Georgia, during March-April 1989 and April-May 1990. The spring 1990 measurements also included the sulphur gases hydrogen sulphide (H 2S), carbonyl sulphide (COS) and carbon disulphide (CS 2). In August 1989 single measurements of these compounds were also conducted in various natural environments of southern Louisiana (coastal waters, saltwater marsh, brackish/freshwater marsh, swamp). The median DMS concentration over Sapelo Island was significantly higher in April-May 1990 (92 ppt) than in March-April 1989 (18 ppt) due to enhanced biogenic DMS emission in spring. Atmospheric DMS levels increased sharply (up to 560 ppt) during advection of polluted air from paper mills located on the coastal mainland. Results obtained from measurements in Louisiana suggest that biogenic sulphur fluxes from soils and/or vegetation are significantly enhanced durign rainfall. H 2S concentrations were highly variable at each study site. Corresponding values ranged consistently higher over swamps and marshes (300-820 ppt) compared to tidal flats (3-510 ppt). Generally, DMS was the dominant biogenic sulphur gas emitted from coastal environments while further inland H 2S was the dominant species. Over all environments studied the relative contribution from natural sulphur sources to atmospheric nss-SO 4 levels ranged between approximately 15 and 50% during the individual measurement periods. Major contributions were made from regional anthropogenic sources and, on the southeastern Atlantic coast, from additional long-range transport of air masses from Africa and Europe. The effects of these sources on aerosol and rainwater acidity levels over each region are discussed.

  1. On the stability of the atmosphere-vegetation system in the Sahara/Sahel region

    NASA Astrophysics Data System (ADS)

    Brovkin, Victor; Claussen, Martin; Petoukhov, Vladimir; Ganopolski, Andrey

    1998-12-01

    A conceptual model has been developed for the analysis of atmosphere-vegetation interaction in subtropical deserts. The model can exhibit multiple stable states in the system: a "desert" equilibrium with low precipitation and absent vegetation and a "green" equilibrium with moderate precipitation and permanent vegetation cover. The conceptual model is applied to interpret the results of two climate-vegetation models: a comprehensive coupled atmosphere-biome model and a simple box model. In both applications, two stable states exist for the western Sahara/Sahel region for the present-day climate, and the only green equilibrium is found for the mid-Holocene climate. The latter agrees well with paleoreconstructions of Sahara/Sahel climate and vegetation. It is shown that for present-day climate the green equilibrium is less probable than the desert equilibrium, and this explains the existence of the Sahara desert as it is today. The difference in albedo between the desert and vegetation cover appears to be the main parameter that controls an existence of multiple stable states. The Charney's mechanism of self-stabilization of subtropical deserts is generalized by accounting for atmospheric hydrology, the heat and moisture exchange at the side boundaries, and taking into account the dynamic properties of the surface. The generalized mechanism explains the self-stabilization of both desert and vegetation in the western Sahara/Sahel region. The role of surface roughness in climate-vegetation interaction is shown to be of secondary importance in comparison with albedo. Furthermore, for the high albedo, precipitation increases with increasing roughness while, for the low albedo, the opposite is found.

  2. Increasing Mississippi river discharge throughout the twenty-first century influenced by changes in climate, land use and atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Tao, B.; Tian, H.; Ren, W.; Yang, J.; Yang, Q.; He, R.; Cai, W. J.; Lohrenz, S. E.

    2014-12-01

    Previous studies have demonstrated that changes in temperature and precipitation (hereafter climate change) would influence river discharge, but the relative importance of climate change, land use, and elevated atmospheric CO2 have not yet been fully investigated. Here we examined how river discharge in the Mississippi River basin in the 21st century might be influenced by these factors using the Dynamic Land Ecosystem Model driven by atmospheric CO2, downscaled GCMs climate and land use scenarios. Our results suggest that river discharge would be substantially enhanced (10.7-59.8%) by the 2090s compared to the recent decade (2000s), though large discrepancies exist among different climate, atmospheric CO2, and land use change scenarios. Our factorial analyses further indicate that the combined effects of land use change and human-induced atmospheric CO2 elevation on river discharge would outweigh climate change effect under the high emission scenario (A2) of Intergovernmental Panel for Climate Change. Our study offers the first attempt to project potential changes in river discharge in response to multiple future environmental changes. It demonstrates the importance of land use change and atmospheric CO2 concentrations in projecting future changes in hydrologic processes. The projected increase river discharge implies that riverine fluxes of carbon, nutrients and pesticide from the MRB to the coastal regions would increase in the future, and thus may influence the states of ocean acidification and hypoxia and deteriorate ocean water quality. Further efforts will also be needed to account for additional environmental factors (such as nitrogen deposition, tropospheric ozone pollution, dam construction, etc.) in projecting changes in the hydrological cycle.

  3. Influence of a stochastic convection parameterization on the statistics of rainfall in the Community Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Kashinath, K.; O'Brien, T. A.; Collins, W.

    2014-12-01

    Understanding the physical mechanisms responsible for extreme weather phenomena and their changing behaviour in a warming world is essential to predict such events. This task, however, is challenging because of the nonlinear behaviour of the climate system, the small scales and fast dynamics of extreme events and the inherent intermittency of our turbulent atmosphere and ocean. Recent work has shown that representing the inherent intermittency and chaotic nature of turbulent sub-grid scale processes, such as convection, via stochastic parameterizations can improve the performance of weather and climate models, including the interaction of sub-grid scale processes and large scale climate. However, the influence of stochastic parameterizations on the prediction of extreme events has not received much attention. In this study we explore the influence of a stochastic parameterization of convection on the statistics of extreme rainfall events in the USA. The deep convection parameterization of the Community Atmosphere Model (CAM5), which is based upon the bulk mass-flux scheme of Zheng and McFarlane, is modified to have a stochastic entrainment rate in the mixing model for the calculation of dilute CAPE. The entrainment events are described by a stochastic Poisson process, based on cloud resolving model simulations by Romps and Kuang [2010]. This modification represents turbulent mixing in the atmosphere in a manner more consistent with large eddy simulations of convection. We find that the stochastic scheme results in an increase in the amounts of both light and intense precipitation, which is in closer agreement with observed rainfall distributions compared to results from CAM5 with its usual deterministic parameterization of convection. The increase is due to changes in both the convective precipitation and the large scale precipitation, which suggests that stochastic entrainment alters not just the sub-grid scale processes but also their interaction with the large scale climate. We use a hindcast-based system developed by O'Brien et al. [abstract submitted to session #2018] to characterize the influence of stochasticity on the fidelity of simulated extremes.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

  6. Atmospheric Transport of Arid Aerosol from Desert Regions of Central Asia

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

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

    SciTech Connect

    Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen; Uhm, Han S.

    2011-10-15

    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.

  9. Improving adhesion of powder coating on PEEK composite: Influence of atmospheric plasma parameters

    NASA Astrophysics Data System (ADS)

    Dupuis, Aurélie; Ho, Thu Huong; Fahs, Ahmad; Lafabrier, Aurore; Louarn, Guy; Bacharouche, Jalal; Airoudj, Aissam; Aragon, Emmanuel; Chailan, Jean-François

    2015-12-01

    In aeronautic industries, powder coatings are increasingly used because of environmental considerations. During the deposition of such a coating on a substrate piece, the main objective is to obtain a good coating/substrate adhesion. In this study, the targeted substrate is a Poly-(Ether EtherKetone)-(PEEK) based composite material. Due to the poor surface energy of PEEK, a surface treatment is necessary in order to enhance its adhesion with the coating. In this purpose, atmospheric plasma treatment has been chosen and the influence of plasma parameters has been studied. Four scan speed nozzles and three gases (Air, N2 and Argon) plasma has been tested. The increase of adhesion with increasing wettability, polarity and nanoroughness has been evidenced. A particular study of the type of grafted polar functionalities according to gas nature allowed to better understand the plasma mechanism and the cross-impact of polarity and nanoroughness in adhesion enhancement.

  10. Magnetic resonance investigation of Zn1-xFexO properties influenced by annealing atmosphere

    NASA Astrophysics Data System (ADS)

    Raita, O.; Popa, A.; Toloman, D.; Stan, M.; Giurgiu, L. M.

    2013-11-01

    ZnO is an attractive system for a wide variety of practical applications, being a chemically stable oxide semiconductor. It has been shown that Fe doping produces ferromagnetic semiconductor at room temperature. This material, therefore, has the potential for use in spintronic devices such as spin transistors, spin light emitting diodes, very high density nonvolatile semiconductor memory and optical emitters. It is believed that oxygen vacancies and substitutional incorporation are important to produce ferromagnetism in semiconductor oxide doped with transition metal ions. The present paper reports detailed electron paramagnetic resonance investigations (EPR) of the samples in order to investigate how annealing atmosphere (Air and Argon) influenced the magnetic behavior of the samples. X-band electron paramagnetic resonance (EPR) studies of Fe3+ ions in Zn1-xFexO powders with x = 1%, 3% is reported. These samples are interesting to investigate as Fe doping produce ferromagnetism in ZnO, making a promising ferromagnetic semiconductor at room temperature.

  11. Robust influences of superparameterized rainfall variability and intensity on land-atmosphere energetics including soil moisture, surface fluxes, and temperature

    NASA Astrophysics Data System (ADS)

    Kooperman, Gabriel; Pritchard, Michael

    2015-04-01

    Land-atmosphere coupling energetics can play critical roles in mediating local weather and climate. Interactions at this hydrologic interface impact the availability of freshwater, droughts, floods, and temperature extremes. Predicting how the hydrological cycle will respond to climate change requires a realistic representation of these complex energy exchange mechanisms in global climate models (GCMs). Conventional GCMs suggest that regions of strong coupling (i.e. where local rainfall and soil moisture fluctuations are correlated) will be most sensitive to climate change. However, these models do not capture some forms of organized convection and are known to distort the diurnal character of rainfall over land. Second-order characteristics of rainfall (variability, frequency, timing, and intensity), in addition to time-integrated climatology, can have a significant impact on the hydrologic cycle. They determine whether rainwater infiltrates the soil or runs off the surface and how much water collected on the vegetation canopy is available for re-evaporation. Here we investigate land-atmosphere interactions in a GCM that explicitly resolves convection, captures organized storms, and improves the diurnal cycle and intensity distribution of rain. In this multi-scale modeling approach called super-parameterization (SP), simplified cloud resolving models are embedded in each grid column of the NCAR Community Atmosphere Model (CAM) to replace conventional parameterizations. SP-CAM captures the broad rainfall intensity distribution and extreme events that are missing in conventional CAM, especially during the mid-latitude summer and in the tropics, exerting a strong influence during the growing season. More intense rainfall reduces canopy interception (and the re-evaporation of rainwater that is often exaggerated in GCMs), increases the rate of rainfall reaching the ground and thus running off the surface, and generally increases the demand on transpiration. As a result, SP-CAM amplifies the Bowen ratio relative to conventional CAM, which is enhanced further with climate change. This amplified Bowen ratio appears to be a robust effect of SP. It is consistent across many regions and model versions with different resolution, cloud microphysics, and land-surface processes, broadening the temperature distribution to include more extreme heat events in SP-CAM.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  13. Journal of Atmospheric and Solar-Terrestrial Physics 66 (2004) 16551668 Ion thermal effects on E-region instabilities

    E-print Network

    Oppenheim, Meers

    2004-01-01

    in the atmosphere. These E-region ionospheric irregularities occur when electrojet polarization electric fields. Geophys. Res. 99 (1994b) 11461). r 2004 Elsevier Ltd. All rights reserved. Keywords: E-region electrojet in the electrojets found near the geomagnetic equator and auroral ovals. Over the last forty years researchers have

  14. Atmospheric CO2 Measurements in Mountainous Terrain to Monitor Regional Fluxes and Local Disturbance Panel 2. Diurnal Variations

    E-print Network

    Stephens, Britton B.

    Overview: The Rocky Mountain Regional Atmospheric Continuous CO2 Network (Rocky RACCOON) includes four high real time to support quality control, local science, and larger scale synthesis efforts (http://raccoon.ucar.edu). Panel 1. Existing Sites The mountain-top RACCOON sites were selected to capture regionally

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

    SciTech Connect

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

    1999-01-01

    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.

  16. Characterization of atmospheric aerosols in the Po valley during the supersito campaigns - Part 3: Contribution of wood combustion to wintertime atmospheric aerosols in Emilia Romagna region (Northern Italy)

    NASA Astrophysics Data System (ADS)

    Pietrogrande, Maria Chiara; Bacco, Dimitri; Ferrari, Silvia; Kaipainen, Jussi; Ricciardelli, Isabella; Riekkola, Marja-Liisa; Trentini, Arianna; Visentin, Marco

    2015-12-01

    This paper investigates the influence of wood combustion on PM in fall/winter that are the most favorable seasonal periods with presumed intense biomass burning for residential heating due to low temperatures. As a part of the Supersito project, nearly 650 PM2.5 samples were daily collected at urban and rural sites in Emilia Romagna (Northern Italy) in five intensive experimental campaigns throughout the years from 2011 to 2014. From specific compounds related to wood combustion a set of 58 organic compounds was determined, such as anhydrosugars, primary biological sugars, low-molecular-weight carboxylic acids, methoxylated phenols, PAHs and carbonaceous components (EC/OC). Levoglucosan was by far the most dominant anhydrosugar, both on a relative and an absolute basis (35-1043 ng m-3), followed by mannosan (7-121 ng m-3) and galactosan (4-52 ng m-3), indicating that wood burning for domestic heating is a diffuse regional source during the seasons studied. Different diagnostic ratios between anhydrosugars and methoxylated phenols were computed to discriminate the prevalent contribution of hardwood as combustion fuel. The investigated 19 high molecular weight PAHs were more abundant at the urban than at the rural site, with mean total value of 4.3 and 3.2 ng m-3 at MS and SP, respectively. The strong contribution of wood combustion to atmospheric PAHs was indicated by the positive correlation between levoglucosan and the most abundant PAHs (R2 = 0.71÷0.79) and individually with benzo(a)pyrene (R2 = 0.79). By using this correlation, it was estimated that wood burning contributed nearly 77% to BaP concentration in the winter months. Based on the ratio between levoglucosan and OC data, it could be concluded that the wood burning contributed about 35% to OC during the cold November-February periods and the contribution was similar at both sampling sites.

  17. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part II: verification of the source term and analysis of regional-scale atmospheric dispersion.

    PubMed

    Terada, Hiroaki; Katata, Genki; Chino, Masamichi; Nagai, Haruyasu

    2012-10-01

    Regional-scale atmospheric dispersion simulations were carried out to verify the source term of (131)I and (137)Cs estimated in our previous studies, and to analyze the atmospheric dispersion and surface deposition during the Fukushima Dai-ichi Nuclear Power Plant accident. The accuracy of the source term was evaluated by comparing the simulation results with measurements of daily and monthly surface depositions (fallout) over land in eastern Japan from March 12 to April 30, 2011. The source term was refined using observed air concentrations of radionuclides for periods when there were significant discrepancies between the calculated and measured daily surface deposition, and when environmental monitoring data, which had not been used in our previous studies, were now available. The daily surface deposition using the refined source term was predicted mostly to within a factor of 10, and without any apparent bias. Considering the errors in the model prediction, the estimated source term is reasonably accurate during the period when the plume flowed over land in Japan. The analysis of regional-scale atmospheric dispersion and deposition suggests that the present distribution of a large amount of (137)Cs deposition in eastern Japan was produced primarily by four events that occurred on March 12, 15-16, 20, and 21-23. The ratio of wet deposition to the total varied widely depending on the influence by the particular event. PMID:22721917

  18. Atmospheric conditions associated with extreme fire activity in the Western Mediterranean region.

    PubMed

    Amraoui, Malik; Pereira, Mário G; DaCamara, Carlos C; Calado, Teresa J

    2015-08-15

    Active fire information provided by TERRA and AQUA instruments on-board sun-synchronous polar MODIS platform is used to describe fire activity in the Western Mediterranean and to identify and characterize the synoptic patterns of several meteorological fields associated with the occurrence of extreme fire activity episodes (EEs). The spatial distribution of the fire pixels during the period of 2003-2012 leads to the identification of two most affected sub-regions, namely the Northern and Western parts of the Iberian Peninsula (NWIP) and Northern Africa (NAFR). The temporal distribution of the fire pixels in these two sub-regions is characterized by: (i) high and non-concurrent inter- and intra-annual variability with maximum values during the summer of 2003 and 2005 in NWIP and 2007 and 2012 in NAFR; and, (ii) high intra-annual variability dominated by a prominent annual cycle with a main peak centred in August in both sub-regions and a less pronounced secondary peak in March only evident in NWIP region. The 34 EEs identified were grouped according to the location, period of occurrence and spatial configuration of the associated synoptic patterns into 3 clusters (NWIP-summer, NWIP-winter and NAFR-summer). Results from the composite analysis reveal similar fire weather conditions (statistically significant positive anomalies of air temperature and negative anomalies of air relative humidity) but associated with different circulation patterns at lower and mid-levels of the atmosphere associated with the occurrence of EEs in each cluster of the Western Mediterranean region. PMID:25889542

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

    SciTech Connect

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  1. Water Vapor Tacers as Diagnostics of the Regional Atmospheric Hydrologic Cycle

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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.

  2. Variability of atmospheric greenhouse gases as a biogeochemical processing signal at regional scale in a karstic ecosystem

    NASA Astrophysics Data System (ADS)

    Borràs, Sílvia; Vazquez, Eusebi; Morguí, Josep-Anton; Àgueda, Alba; Batet, Oscar; Cañas, Lídia; Curcoll, Roger; Grossi, Claudia; Nofuentes, Manel; Occhipinti, Paola; Rodó, Xavier

    2015-04-01

    The South-eastern area of the Iberian Peninsula is an area where climatic conditions reach extreme climatic conditions during the year, and is also heavily affected by the ENSO and NAO. The Natural Park of Cazorla, Segura de la Sierra and Las Villas is located in this region, and it is the largest protected natural area in Spain (209920 Ha). This area is characterized by important climatic and hydrologic contrasts: although the mean annual precipitation is 770 nm, the karstic soils are the main cause for water scarcity during the summer months, while on the other hand it is in this area where the two main rivers of Southern Spain, the Segura and the Guadalquivir, are born. The protected area comprises many forested landscapes, karstic areas and reservoirs like Tranco de Beas. The temperatures during summer are high, with over 40°C heatwaves occurring each year. But during the winter months, the land surface can be covered by snow for periods of time up until 30 days. The ENSO and NAO influences cause also an important inter annual climatic variability in this area. Under the ENSO, autumnal periods are more humid while the following spring is drier. In this area vegetal Mediterranean communities are dominant. But there are also a high number of endemic species and derelict species typical of temperate climate. Therefore it is a protected area with high specific diversity. Additionally, there is an important agricultural activity in the fringe areas of the Natural Park, mainly for olive production, while inside the Park this activity is focused on mountain wheat production. Therefore the diverse vegetal communities and landscapes can easily be under extreme climatic pressures, affecting in turn the biogeochemical processes at the regional scale. The constant, high-frequency monitoring of greenhouse gases (GHG) (CO2 and CH4) integrates the biogeochemical signal of changes in this area related to the carbon cycle at the regional scale, capturing the high diversity of landscapes and climatic variability. The monitoring is carried out in one of the stations of the ClimaDat network, which consists of eight GHG monitoring stations in highly preserved ecosystems which are very sensitive to climate change in Spain. This constant monitoring will allow relating changes in terrestrial ecosystems, hydrological processes and atmospheric transport of GHG. The goal of the presentation is to show the results obtained since September 2013 through continuous monitoring, focusing on the seasonal changes in precipitation, temperature, and CO2 and CH4 changes in atmospheric concentrations.

  3. The National Science Foundation's Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) Student Community

    NASA Astrophysics Data System (ADS)

    Sox, L.; Duly, T.; Emery, B.

    2014-12-01

    The National Science Foundation sponsors Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) Workshops, which have been held every summer, for the past 29 years. CEDAR Workshops are on the order of a week long and at various locations with the goal of being close to university campuses where CEDAR type scientific research is done. Although there is no formal student group within the CEDAR community, the workshops are very student-focused. Roughly half the Workshop participants are students. There are two Student Representatives on the CEDAR Science Steering Committee (CSSC), the group of scientists who organize the CEDAR Workshops. Each Student Representative is nominated by his or her peers, chosen by the CSSC and then serves a two year term. Each year, one of the Student Representatives is responsible for organizing and moderating a day-long session targeted for students, made up of tutorial talks, which aim to prepare both undergraduate and graduate students for the topics that will be discussed in the main CEDAR Workshop. The theme of this session changes every year. Past themes have included: upper atmospheric instrumentation, numerical modeling, atmospheric waves and tides, magnetosphere-ionosphere coupling, equatorial aeronomy and many others. Frequently, the Student Workshop has ended with a panel of post-docs, researchers and professors who discuss pressing questions from the students about the next steps they will take in their careers. As the present and past CSSC Student Representatives, we will recount a brief history of the CEDAR Workshops, our experiences serving on the CSSC and organizing the Student Workshop, a summary of the feedback we collected about the Student Workshops and what it's like to be student in the CEDAR community.

  4. Evaluation of size segregation of elemental carbon emission in Europe: influence on atmospheric long-range transportation

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Cheng, Y. F.; Nordmann, S.; Birmili, W.; Denier van der Gon, H. A. C.; Ma, N.; Wolke, R.; Wehner, B.; Sun, J.; Spindler, G.; Mu, Q.; Pöschl, U.; Su, H.; Wiedensohler, A.

    2015-11-01

    Elemental Carbon (EC) has significant impact on human health and climate change. In order to evaluate the size segregation of EC emission and investigation of its influence on atmospheric transport processes in Europe, we used the fully coupled online Weather Research and Forecasting/Chemistry model (WRF-Chem) at a resolution of 2 km focusing on a region in Germany, in conjunction with a high-resolution EC emission inventory. The ground meteorology conditions, vertical structure and wind pattern were well reproduced by the model. The simulations of particle number/mass size distributions were evaluated by observations taken at the central European background site Melpitz. The fine mode aerosol was reasonably well simulated, but the coarse mode was substantially overestimated by the model. We found that it was mainly due to the nearby point source plume emitting a high amount of EC in the coarse mode. The comparisons between simulated EC and Multi-angle Absorption Photometers (MAAP) measurements at Melpitz, Leipzig-TROPOS and Bösel indicated that coarse mode EC (ECc) emission in the nearby point sources might be overestimated by a factor of 2-10. The emission fraction of EC in coarse mode was overestimated by about 10-30 % for Russian and 5-10 % for Eastern Europe (e.g.: Poland and Belarus), respectively. This overestimation in ECc emission fraction makes EC particles having less opportunity to accumulate in the atmosphere and participate to the long range transport, due to the shorter lifetime of coarse mode aerosol. The deposition concept model showed that the transported EC mass from Warsaw and Moskva to Melpitz may be reduced by 25-35 and 25-55 % respectively, due to the overestimation of ECc emission fraction. This may partly explain the underestimation of EC concentrations for Germany under eastern wind pattern in some other modelling research.

  5. Influence of different land surfaces on atmospheric conditions measured by a wireless sensor network

    NASA Astrophysics Data System (ADS)

    Lengfeld, Katharina; Ament, Felix

    2010-05-01

    Atmospheric conditions close to the surface, like temperature, wind speed and humidity, vary on small scales because of surface heterogeneities. Therefore, the traditional measuring approach of using a single, highly accurate station is of limited representativeness for a larger domain, because it is not able to determine these small scale variabilities. However, both the variability and the domain averages are important information for the development and validation of atmospheric models and soil-vegetation-atmosphere-transfer (SVAT) schemes. Due to progress in microelectronics it is possible to construct networks of comparably cheap meteorological stations with moderate accuracy. Such a network provides data in high spatial and temporal resolution. The EPFL Lausanne developed such a network called SensorScope, consisting of low cost autonomous stations. Each station observes air and surface temperature, humidity, wind direction and speed, incoming solar radiation, precipitations, soil moisture and soil temperature and sends the data via radio communication to a base station. This base station forwards the collected data via GSM/GPRS to a central server. Within the FLUXPAT project in August 2009 we deployed 15 stations as a twin transect near Jülich, Germany. One aim of this first experiment was to test the quality of the low cost sensors by comparing them to more accurate reference measurements. It turned out, that although the network is not highly accurate, the measurements are consistent. Consequently an analysis of the pattern of atmospheric conditions is feasible. For example, we detect a variability of ± 0.5K in the mean temperature at a distance of only 2.3 km. The transect covers different types of vegetation and a small river. Therefore, we analyzed the influence of different land surfaces and the distance to the river on meteorological conditions. On the one hand, some results meet our expectations, e.g. the relative humidity decreases with increasing distance to the river. But on the other hand we found unexpected anomalies in the air temperature, which will be discussed in detail by selected case studies.

  6. Atmospheric sulfur hexafluoride in-situ measurements at the Shangdianzi regional background station in China.

    PubMed

    Yao, Bo; Zhou, Lingxi; Xia, Lingjun; Zhang, Gen; Guo, Lifeng; Liu, Zhao; Fang, Shuangxi

    2014-12-01

    We present in-situ measurements of atmospheric sulfur hexafluoride (SF6) conducted by an automated gas chromatograph-electron capture detector system and a gas chromatography/mass spectrometry system at a regional background site, Shangdianzi, in China, from June 2009 to May 2011, using the System for Observation of Greenhouse gases in Europe and Asia and Advanced Global Atmospheric Gases Experiment (AGAGE) techniques. The mean background and polluted mixing ratios for SF6 during the study period were 7.22 × 10?¹² (mol/mol, hereinafter) and 8.66 × 10?¹², respectively. The averaged SF6 background mixing ratios at Shangdianzi were consistent with those obtained at other AGAGE stations located at similar latitudes (Trinidad Head and Mace Head), but larger than AGAGE stations in the Southern Hemisphere (Cape Grim and Cape Matatula). SF6 background mixing ratios increased rapidly during our study period, with a positive growth rate at 0.30 × 10?¹² year?¹. The peak to peak amplitude of the seasonal cycle for SF6 background conditions was 0.07 × 10?¹², while the seasonal fluctuation of polluted conditions was 2.16 × 10?¹². During the study period, peak values of SF6 mixing ratios occurred in autumn when local surface horizontal winds originated from W/WSW/SW/SWS/S sectors, while lower levels of SF6 mixing ratios appeared as winds originated from N/NNE/NE/ENE/E sectors. PMID:25499493

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

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

    SciTech Connect

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

    1993-10-01

    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.

  9. Influence of the radiation pressure on the planetary exospheres: density profiles, escape flux and atmospheric stability

    NASA Astrophysics Data System (ADS)

    Beth, A.; Garnier, P.; Toublanc, D.; Dandouras, I.; Mazelle, C.

    2015-10-01

    The uppermost layer of the atmosphere, the exosphere,is not well-known in its global structure since the densities are very low compared to instrument detection capabilities. Because of rare collisions and high Knudsen numbers, the motion of light species (H,H2, ...)in the corona is essentially determined by the external forces : the gravitation from the planet, the radiation pressure, as well the stellar gravity. In this work, we calculate rigorously and analytically,based on the Hamiltonian mechanics and Liouville theorem, the impact of the radiation pressure and gravitation from the planet on the structure of the exosphere. This approach was partially used by Bishop and Chamberlain (1989) but only in the 2D case : we extend it to the 3D case. Assuming a collisionless exosphere and a constant radiation pressure near the planet, we determine the density profiles for ballistic particles (the main contribution for densities in the lower exosphere) for light species as a function of the angle with respect to the Sun direction. We also obtain an analytical formula for the escape flux at the subsolar point, which can be compared with the Jeans' escape flux. Finally, we study the effect of the radiation pressure on the zero velocity curves, position of the Roche lobe and Hill's region for the well-known Three-Body problem especially for Hot Jupiters and discuss about the validity of our model. The goal is to bring some constraints on modelling of exoplanet atmospheres.

  10. Regional assessment of atmospheric organic and black carbon in South Africa

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  11. Atmosphere

    NASA Astrophysics Data System (ADS)

    Ghosh, D.; Mitra, S. K.

    2014-05-01

    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.

  12. Influence of preonset land atmospheric conditions on the Indian summer monsoon rainfall variability

    NASA Astrophysics Data System (ADS)

    Rai, Archana; Saha, Subodh K.; Pokhrel, Samir; Sujith, K.; Halder, Subhadeep

    2015-05-01

    A possible link between preonset land atmospheric conditions and the Indian summer monsoon rainfall (ISMR) is explored. It is shown that, the preonset positive (negative) rainfall anomaly over northwest India, Pakistan, Afghanistan, and Iran is associated with decrease (increase) in ISMR, primarily in the months of June and July, which in turn affects the seasonal mean. ISMR in the months of June and July is also strongly linked with the preonset 2 m air temperature over the same regions. The preonset rainfall/2 m air temperature variability is linked with stationary Rossby wave response, which is clearly evident in the wave activity flux diagnostics. As the predictability of Indian summer monsoon relies mainly on the El Niño-Southern Oscillation (ENSO), the found link may further enhance our ability to predict the monsoon, particularly during a non-ENSO year.

  13. Influence of ketamine on regional brain glucose use

    SciTech Connect

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

    1988-08-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  15. NAO influence on net sea ice production and exchanges in the Arctic region

    E-print Network

    Hu, Aixue

    in the Arctic region is an essential requirement for prediction of the high latitude climate evolution. Variations in sea ice exchanges between the Arctic and its adjacent seas will change the surface buoyancyNAO influence on net sea ice production and exchanges in the Arctic region Aixue Hu, Claes Rooth

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

    E-print Network

    Evans, Jason

    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

  17. Role of atmospheric heating over the South China Sea and western Pacific regions in modulating Asian summer climate under the global warming background

    NASA Astrophysics Data System (ADS)

    He, Bian; Yang, Song; Li, Zhenning

    2015-07-01

    The response of monsoon precipitation to global warming, which is one of the most significant climate change signals at the earth's surface, exhibits very distinct regional features, especially over the South China Sea (SCS) and adjacent regions in boreal summer. To understand the possible atmospheric dynamics in these specific regions under the global warming background, changes in atmospheric heating and their possible influences on Asian summer climate are investigated by both observational diagnosis and numerical simulations. Results indicate that heating in the middle troposphere has intensified in the SCS and western Pacific regions in boreal summer, accompanied by increased precipitation, cloud cover, and lower-tropospheric convergence and decreased sea level pressure. Sensitivity experiments show that middle and upper tropospheric heating causes an east-west feedback pattern between SCS and western Pacific and continental South Asia, which strengthens the South Asian High in the upper troposphere and moist convergence in the lower troposphere, consequently forcing a descending motion and adiabatic warming over continental South Asia. When air-sea interaction is considered, the simulation results are overall more similar to observations, and in particular the bias of precipitation over the Indian Ocean simulated by AGCMs has been reduced. The result highlights the important role of air-sea interaction in understanding the changes in Asian climate.

  18. 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)

    Cavalcanti, I. F.

    2013-05-01

    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.

  19. Regional and large-scale influences on seasonal to interdecadal variability in Caribbean surface air temperature in CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Ryu, Jung-Hee; Hayhoe, Katharine

    2015-07-01

    We evaluate the ability of global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) to reproduce observed seasonality and interannual variability of temperature over the Caribbean, and compare these with simulations from atmosphere-only (AMIP5) and previous-generation CMIP3 models. Compared to station and gridded observations, nearly every CMIP5, CMIP3 and AMIP5 simulation tends to reproduce the primary inter-regional features of the Caribbean annual temperature cycle. In most coupled model simulations, however, boreal summer temperature lags observations by about 1 month, with a similar lag in the simulated annual cycle of sea surface temperature (SST), and a systematic cold bias in both climatological annual mean air temperature and SST. There is some improvement from CMIP3 to CMIP5 but the bias is still marked compared to AMIP5 and observations, implying that biases in the annual temperature cycle may originate in the ocean component of the coupled models. This also suggests a tendency for models to over-emphasize the influence of SSTs on near-surface temperature, a bias that may be exacerbated by model tendency to over-estimate ocean mixed layer depth as well. In contrast, we find that both coupled and atmosphere-only models tend to reasonably simulate the response of observed temperature to global temperature, to regional and large-scale variability across the Caribbean region and the Gulf of Mexico, and even to more remote Atlantic and Pacific influences. These findings contribute to building confidence in the ability of coupled models to simulate the effect of global-scale change on the Caribbean.

  20. 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...

  1. Magnetohydrodynamic Model of Europa's Interaction with Jupiter's Magnetosphere: Influence of Plumes in Europa's Atmosphere on the Plasma Environment

    NASA Astrophysics Data System (ADS)

    Bloecker, A.; Saur, J.; Roth, L.; Hartkorn, O. A.

    2014-12-01

    We develop a three-dimensional magnetohydrodynamic (MHD) model to study the influence of plumes in Europa's atmosphere on the interaction with Jupiter's magnetosphere and plasma environment. We consider the cases when Europa is located in, above and below the magnetospheric current sheet. Recently, Roth et al. (2014) discovered transient water vapor plumes near Europa's south pole. Here we provide a structured study of the influence of plumes in Europa's atmosphere on the local plasma interaction and the Alfvén wings. In our model we have included an asymmetric atmosphere of Europa, the electromagnetic induction in a subsurface water ocean, the plasma production and loss due to electron impact ionization and dissociative recombination. Additionally, our model takes into account different types of model plumes at the south pole. Our analysis suggests that the plume modifies the global plasma interaction of Europa. The strength of the modification depends on the physical properties of the plume.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  4. Influences of fireworks on chemical characteristics of atmospheric fine and coarse particles during Taiwan's Lantern Festival

    NASA Astrophysics Data System (ADS)

    Tsai, Hsieh-Hung; Chien, Li-Hsing; Yuan, Chung-Shin; Lin, Yuan-Chung; Jen, Yi-Hsiu; Ie, Iau-Ren

    2012-12-01

    In recent years, the celebration activities of various folk-custom festivals have been getting more and more attention from the citizens in Taiwan. Festivities throughout the whole island are traditionally accompanied by loud and brightly colored firework displays. Among these activities, the firework displays during Taiwan's Lantern Festival in Kaohsiung harbor is one of the largest festivals in Taiwan each year. Therefore, it is of importance to investigate the influence of fireworks displays on the ambient air quality during the Taiwan's Lantern Festival. Field measurements of atmospheric particulate matter (PM) were conducted on February 9th-11th, 2009 during Taiwan's Lantern Festival in Kaohsiung City. Moreover, three kinds of fireworks powders obtained from the same manufacturing factory producing Kaohsiung Lantern Festival fireworks were burned in a self-designed combustion chamber to determine the physicochemical properties of the fireworks' particles and to establish the source profile of firework burning. Several metallic elements of PM during the firework display periods were notably higher than those during the non-firework periods. The concentrations of Mg, K, Pb, and Sr in PM2.5 during the firework periods were 10 times higher than those during the non-firework periods. Additionally, the Cl-/Na+ ratio was approximately 3 during the firework display periods as Cl- came from the chlorine content of the firework powder. Moreover, the OC/EC ratio increased up to 2.8. Results obtained from PCA and CMB receptor modeling showed that major sources of atmospheric particles during the firework display periods in Kaohsiung harbor were fireworks, vehicular exhausts, soil dusts and marine sprays. Particularly, on February 10th, the firework displays contributed approximately 25.2% and 16.6% of PM10 at two downwind sampling sites, respectively.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  6. Response of the regional water cycle to an increase of atmosphere moisture related to global warming

    SciTech Connect

    Frei, C.; Widmann, M.; Luethi, D.

    1997-11-01

    This study examines the sensitivity of the mid-latitude regional hydrological cycle to an imposed warming. Mesoscale limited-area climate simulations over Europe are performed. The modelling study is complemented with a detailed analysis of the observed precipitation and circulation trends in the same region. It is demonstrated that an increase of the moisture content leads to an enhancement of the model`s water cycle during the synoptically active seasons. The simulations suggest that this mechanism may contribute towards an increase in mean precipitation and more frequency occurrence of heavy precipitation events. Observational analysis results illustrate that the relationship between precipitation and atmospheric moisture seen in the climate simulations constitutes a possible physical mechanism relevant for the interpretation of the observed trends. A key feature of the model results is the pronounced increase in the frequency of strong precipitation events associated with the intensification of the water cycle. This large sensitivity highlights the vulnerability of the precipitation climate with respect to global climate change. 19 refs., 2 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

    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.

  9. Influence of atmospheric CO2 enrichment on nitrous oxide flux in a temperate forest ecosystem

    NASA Astrophysics Data System (ADS)

    Phillips, Rebecca L.; Whalen, Stephen C.; Schlesinger, William H.

    2001-09-01

    Long-term exposure of native vegetation to elevated atmospheric carbon dioxide (CO2) is expected to increase the water content and the input of labile carbon (C) to soil, which could stimulate nitrification and denitrification and enhance nitrous oxide (N2O) emissions. We measured N2O fluxes for 2 years in a Pinus taeda forest that was continuously enriched 200 ?L L-1 CO2 above the ambient atmospheric CO2 concentration (˜560 ?L L-1) beginning 16 months prior to our study. Soil treated with elevated CO2 showed higher N2O emissions at low winter temperatures than the ambient CO2 control. Conversely, soil treated with elevated CO2 showed lower N2O emissions at high summer temperatures than the control soil. Annual N2O fluxes, however, were similar between treatments (˜6600 ?g m-2). Factors that influence denitrification and N2O production were investigated in the laboratory using intact soil core incubations. Nitrate additions (0.17 mg KNO3-N g-1 ) to intact soil cores during laboratory incubations stimulated total N2O production as well as denitrification in both treatments, whereas glucose additions lowered N2O production in both treatments. These experiments demonstrated that N2O production is strongly limited by available nitrogen (N) and that the addition of labile C is likely to reduce the amount of N2O produced by nitrification. Our results collectively suggest that CO2 enrichment of this N-limited ecosystem may reduce N2O flux during the growing season, when soil C inputs and plant-microbial competition for NH4+ are high. Alternatively, elevated CO2 may enhance N2O flux in the winter, when conditions are moist and cold and plants are less active. The potential indirect effects of CO2 enrichment (greater soil moisture and labile C inputs) could reduce N2O flux from nitrification in summer and enhance N2O flux from denitrification in winter, resulting in no net change in total ecosystem N2O flux at the soil-atmosphere interface.

  10. Multivariate weather prediction with atmospheric analogs: predictors and probabilistic prediction skill for different European regions

    NASA Astrophysics Data System (ADS)

    Raynaud, Damien; Hingray, Benoit; Chardon, Jeremy; Anquetin, Sandrine; Favre, Anne-Catherine; François, Baptiste; Vautard, Robert; Tobin, Isabelle

    2015-04-01

    Among the usual methodologies of dynamical or statistical downscaling of climate model, the Analog method appears to be one of the simplest regarding its conceptual nature and its computational costs (Lorentz, 1969). It assumes strong relationships between large scale meteorological variables (predictors) and local weather variables (predictants) so that for two similar large scale situations, the regional consequences on local weather are supposed to be identical. Despite its simplicity, its skill for local scale and/or regional scale prediction is often reported to be very satisfactory. The Analog method has been widely used in Europe to produce precipitation and temperature predictions. For an increasing number of impact studies (e.g. hydrological ones), weather scenarios have to be multivariate and must include additional variables such as wind or radiation. The development of relevant multivariate weather series is however challenging. Weather scenarios have especially to be physically consistent between all weather variables. This issue, which may be critical when relevant hydrological scenarios have to be produced, was to our knowledge fairly not explored. The Analog method has the ability to easily tackle this problem selecting the same analog date for all the weather predictants and thus insuring automatically the physical consistency. However, the best analogs of a given simulation day are likely to depend on the predictant considered. Achieving physical consistency between variables, which implies optimizing the method in a multivariate approach, therefore a priori requires finding a compromise between the different predictors which would be the best for the different predictant taken separately. For the present study, we use a stepwise Analog method for the probabilistic prediction of regional precipitation, temperature, wind and solar radiation. We explore for 12 regions across Europe the variability and diversity of the most skillful parameterisation of the method in terms of predictors (variable, atmospheric level, shape and size of the geographical domain used for the analogs identification). Predictors are extracted from ERA-Interim reanalyses. Predictants are obtained from the European Climate Assessment and Dataset for precipitation and temperature and derived from high resolution Weather Research and Forecasting model simulations (Tobin et al., 2014) for wind and solar radiation pseudo-observations. We evaluate the method's ability to correctly reproduce the recent past climate of the regions and we discuss how the results vary depending on the target region. We also discuss for each predictant the loss of prediction performances due to the multivariate approach compared to the usual univariate one. Lorenz, E. N., (1969) Atmospheric predictability as revealed by naturally occurring analogues. J. Atmos. Sci., 26, 636-646. Tobin, I., Vautard, R., Balog, I., Bréon, F. M., Jerez, S., Ruti, P. M., ... & Yiou, P. (2014). Assessing climate change impacts on European wind energy from ENSEMBLES high-resolution climate projections. Climatic Change, 1-14.

  11. The influence of atmospheric dynamics and climate modes on mean and extreme values of column ozone over the United States

    NASA Astrophysics Data System (ADS)

    Petropavlovskikh, I. V.; Johnson, B.; Evans, R. D.; Manney, G. L.; Rieder, H.

    2013-12-01

    Column ozone measurements are available from five US stations since the 1960s. These time series contain valuable information about the inter-annual variability and trends in the atmospheric ozone field related to natural and anthropogenic processes. In addition to total column measurements Umkehr ozone profiles are derived on every clear, sunny day in Boulder, CO, since 1978. These vertical measurements allow for the attributing total column ozone variability to processes of both tropospheric or stratospheric origin. It is well known that ozone in the free troposphere and lower stratosphere is greatly influenced by atmospheric dynamics. Equivalent Latitude and the position of the individual stations with respect to the subtropical and polar jets can be used to relate the variability of total ozone to transport processes. In this study we use data of all five long-term Dobson stations across the US to investigate the influence of atmospheric dynamics and climate modes, i.e., the Northern Atlantic Oscillation (NAO) and the El Nino Southern Oscillation (ENSO) on total ozone variability and trends since the 1960s. In addition to standard evaluation techniques we utilize a so called STL-decomposition method (Seasonal-Trend decomposition procedure based on Loess) and methods of statistical extreme value theory (EVT) to address the temporal variability and trends in the Dobson data, as well as synoptic-scale meteorological (i.e., subtropical jets) and climate variability. While ozone depleting substances dominate the overall negative trend in column ozone over the observational record, our analysis shows that dynamical features such as the Quasi-Biennial Oscillation (QBO) and climate modes such as ENSO and NAO contribute significantly to ozone variability (and trends) at all 5 US Dobson stations. Some individual stations capture extremes that reflect regional events more strongly than others; the signature of such events becomes clearer when comparing ozone variability between stations. Our results show that ';';fingerprints' of the dynamical features are better captured in the tails (i.e., the extremes) than in the bulk (i.e., the mean) of the observational records. Further, we apply a statistical modeling approach to the ozone data set to attribute ozone variability and trends to individual driving forces associated with natural and anthropogenic causes. Here we find significant changes in trends derived with and without extreme events, which is consistent with previous analysis of European sites and satellite data at mid-latitudes. For the Umkehr data we test if and how the sampling limitation affects the detection and magnitude of dynamical 'fingerprints' and trends. Here we find that sampling affects the magnitude of the variability though not the pattern of variation (i.e., the timing of low and high periods). Our study shows that dynamical features and climate modes have contributed significantly to both variability and trends in US ozone records and show particular influence on the frequency of ozone extremes .

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  13. 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)

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

    2006-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Strawbridge, K. B.

    2012-12-01

    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.

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  17. Analyses of spectroscopic and atmospheric parameter influences on radiative heating and cooling rates in the middle and lower atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Haus, R.; Kappel, D.; Arnold, G.

    2015-10-01

    Radiative fluxes and temperature change rates in the middle and lower atmosphere of Venus (0-100 km) are calculated over the broad spectral range 0.125-1000 ?m applying a radiative transfer model. Responses of these quantities to both spectroscopic model parameter changes and atmospheric parameter variations are examined in great detail. A new model for the unknown UV absorber is proposed. The calculated radiative cooling/heating rates are very reliable at altitudes below 95/85 km at fixed atmospheric conditions with maximum uncertainties of about 0.25 K/day. Heating uncertainties may reach 3-5 K/day at 100 km. Cooling rates strongly respond to variations of atmospheric thermal structure, while heating rates are less sensitive. Except for episodic SO2 boosts, the influence of mesospheric minor gas abundance variations is rather small, but variations of cloud mode parameters may significantly alter radiative temperature change rates up to 50% in Venus' lower mesosphere and upper troposphere.

  18. Dust aerosol radiative effect and influence on urban atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Chen, M.; Li, L.

    2007-11-01

    An 1.5-level-closure and 3-D non-stationary atmospheric boundary layer (ABL) model and a radiation transfer model with the output of Weather Research and Forecast (WRF) Model and lidar AML-1 are employed to simulate the dust aerosol radiative effect and its influence on ABL in Beijing for the period of 23-26 January 2002 when a dust storm occurred. The simulation shows that daytime dust aerosol radiative effect heats up the ABL at the mean rate of about 0.68 K/h. The horizontal wind speed from ground to 900 m layer is also overall increased, and the value changes about 0.01 m/s at 14:00 LT near the ground. At night, the dust aerosol radiative effect cools the ABL at the mean rate of -0.21 K/h and the wind speed lowers down at about -0.19 m/s at 02:00 LT near the ground.

  19. 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)

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

    2015-11-01

    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.

  20. Does wet precipitation represent local and regional atmospheric transportation by perfluorinated alkyl substances?

    PubMed

    Taniyasu, Sachi; Yamashita, Nobuyoshi; Moon, Hyo-Bang; Kwok, Karen Y; Lam, Paul K S; Horii, Yuichi; Petrick, Gert; Kannan, Kurunthachalam

    2013-05-01

    Perfluorinated alkyl substances (PFASs) have been found widely in the environment including remote marine locations. The mode of transport of PFASs to remote marine locations is a subject of considerable scientific interest. Assessment of distribution of PFASs in wet precipitation samples (i.e., rainfall and snow) collected over an area covering continental, coastal, and open ocean will enable an understanding of not only the global transport but also the regional transport of PFASs. Nevertheless, it is imperative to examine the representativeness and suitability of wet precipitation matrixes to allow for drawing conclusions on the transport PFASs. In this study, we collected wet precipitation samples including rainfall, surface snow, and snow core from several locations in Japan to elucidate the suitability of these matrixes for describing local and regional transport of PFASs. Rain water collected at various time intervals within a single rainfall event showed high fluxes of PFASs in the first 1-mm deposition. The scavenging rate of PFASs by wet deposition varied depending on the fluorocarbon chain length of PFAS. The depositional fluxes of PFASs measured for continental (Tsukuba, Japan) and open ocean (Pacific Ocean, 1000km off Japanese coast) locations were similar, on the order of a few nanograms per square meter. The PFAS profiles in "freshly" deposited and "aged" (deposited on the ground for a few days) snow samples taken from the same location varied considerably. The freshly deposited snow represents current atmospheric profiles of PFASs, whereas the aged snow sample reflects sequestration of local sources of PFASs from the atmosphere. Post-depositional modifications in PFAS profiles were evident, suggesting reactions of PFASs on snow/ice surface. Transformation of precursor chemicals such as fluorotelomer alcohols into perfluoroalkylcarboxylates is evident on snow surface. Snow cores have been used to evaluate time trends of PFAS contamination in remote environments. Snow collected at various depths from a core of up to 7.7m deep, at Mt. Tateyama (2450m), Japan, showed the highest concentrations of PFASs in the surface layer and the concentrations decreased with increasing depth for most PFASs, except for perfluorobutanesulfonate (PFBS). Downward movement of highly water soluble PFASs such as PFBS, following melting and freezing cycles of snow, was evident from the analysis of snow core. PMID:23506970

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

    NASA Astrophysics Data System (ADS)

    Patterson, R. Timothy; Swindles, Graeme T.

    2015-11-01

    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.

  2. Improving estimations of greenhouse gas transfer velocities by atmosphere-ocean couplers in Earth-System and regional models

    NASA Astrophysics Data System (ADS)

    Vieira, V. M. N. C. S.; Sahlée, E.; Jurus, P.; Clementi, E.; Pettersson, H.; Mateus, M.

    2015-09-01

    Earth-System and regional models, forecasting climate change and its impacts, simulate atmosphere-ocean gas exchanges using classical yet too simple generalizations relying on wind speed as the sole mediator while neglecting factors as sea-surface agitation, atmospheric stability, current drag with the bottom, rain and surfactants. These were proved fundamental for accurate estimates, particularly in the coastal ocean, where a significant part of the atmosphere-ocean greenhouse gas exchanges occurs. We include several of these factors in a customizable algorithm proposed for the basis of novel couplers of the atmospheric and oceanographic model components. We tested performances with measured and simulated data from the European coastal ocean, having found our algorithm to forecast greenhouse gas exchanges largely different from the forecasted by the generalization currently in use. Our algorithm allows calculus vectorization and parallel processing, improving computational speed roughly 12× in a single cpu core, an essential feature for Earth-System models applications.

  3. Hygroscopic properties of atmospheric aerosol particles over the Eastern Mediterranean: implications for regional direct radiative forcing under clean and polluted conditions

    NASA Astrophysics Data System (ADS)

    Stock, M.; Cheng, Y. F.; Birmili, W.; Massling, A.; Wehner, B.; Müller, T.; Leinert, S.; Kalivitis, N.; Mihalopoulos, N.; Wiedensohler, A.

    2011-05-01

    This work examines the effect of direct radiative forcing of aerosols in the eastern Mediterranean troposphere as a function of air mass composition, particle size distribution and hygroscopicity, and relative humidity (RH). During intensive field measurements on the island of Crete, Greece, the hygroscopic properties of atmospheric particles were determined using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) and a Hygroscopicity Differential Mobility Analyzer-Aerodynamic Particle Sizer (H-DMA-APS). Similar to former studies, the H-TDMA identified three hygroscopic sub-fractions of particles in the sub-?m range: a more hygroscopic group, a less hygroscopic group and a nearly hydrophobic particle group. The average hygroscopic particle growth factors at 90 % RH were a significant function of particle mobility diameter (Dp): 1.42 (± 0.05) at 30 nm compared to 1.63 (± 0.07) at 250 nm. The H-DMA-APS identified up to three hygroscopic sub-fractions at mobility diameters of 1.0 and 1.2 ?m. The data recorded between 12 August and 20 October 2005 were classified into four distinct synoptic-scale air mass types distinguishing between different regions of origin (western Mediterranean vs. the Aegean Sea) as well as the degree of continental pollution (marine vs. continentally influenced). The hygroscopic properties of particles with diameter Dp?150 nm showed the most pronounced dependency on air mass origin, with growth factors in marine air masses exceeding those in continentally influenced air masses. Particle size distributions and hygroscopic growth factors were used to calculate aerosol light scattering coefficients at ambient RH using a Mie model. A main result was the pronounced enhancement of particle scattering over the eastern Mediterranean due to hygroscopic growth, both in the marine and continentally influenced air masses. When RH reached its summer daytime values around 70-80 %, up to 50-70 % of the calculated visibility reduction was due to the hygroscopic growth of the particles by water compared to the effect of the dry particles alone. The estimated aerosol direct radiative forcings for both, marine and continentally influenced air masses were negative indicating a net cooling of the atmosphere due to the aerosol. The radiative forcing ?Fr was nevertheless governed by the total aerosol concentration most of the time: ?Fr was typically more negative for continentally influenced aerosols (ca. -4 W m-2) compared to rather clean marine aerosols (ca. -1.5 W m-2). When RH occasionally reached 90 % in marine air masses, ?Fr even reached values down to -7 W m-2. Our results emphasize, on the basis of explicit particle hygroscopicity measurements, the relevance of ambient RH for the radiative forcing of regional atmospheres.

  4. Hygroscopic properties of atmospheric aerosol particles over the Eastern Mediterranean: implications for regional direct radiative forcing under clean and polluted conditions

    NASA Astrophysics Data System (ADS)

    Stock, M.; Cheng, Y. F.; Birmili, W.; Massling, A.; Wehner, B.; Müller, T.; Leinert, S.; Kalivitis, N.; Mihalopoulos, N.; Wiedensohler, A.

    2010-11-01

    This work examines the effect of direct radiative forcing of aerosols in the eastern Mediterranean troposphere as a function of air mass composition, particle size distribution and hygroscopicity, and relative humidity (RH). During intensive field measurements on the island of Crete, Greece, the hygroscopic properties of atmospheric particles were determined using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) and a Hygroscopicity Differential Mobility Analyzer - Aerodynamic Particle Sizer (H-DMA-APS). Like in several studies before, the H-TDMA identified three hygroscopic sub-fractions of particles in the sub-?m range: a more hygroscopic group, a less hygroscopic group and a nearly hydrophobic particle group. The hygroscopic particle growth factors at 90% RH were a significant function of particle mobility diameter (Dp): 1.42 (± 0.05) at 30 nm compared to 1.63 (± 0.07) at 250 nm. The H-DMA-APS identified up to three hygroscopic sub-fractions at mobility diameters of 1.0 and 1.2 ?m. All data recorded between 12 August and 20 October, 2005 were classified into four distinct synoptic-scale air mass types distinguishing between different regions of origin (western Mediterranean vs. the Aegean Sea) as well as the degree of continental pollution (marine vs. continentally influenced). The hygroscopic properties of particles with diameter Dp ? 150 nm showed the most pronounced dependency on air mass origin, with growth factors in marine air masses exceeding those in more continentally influenced air masses. Particle size distributions and hygroscopic growth factors were employed to calculate aerosol light scattering coefficients at ambient RH using a Mie model. A main result was the pronounced enhancement of particle scattering over the eastern Mediterranean due to hygroscopic growth, both in the marine and continentally influenced air masses. When RH reached its daytime values around 70-80% in summer, up to 50-70% of the calculated visibility reduction was due to the hygroscopic growth of the particles by water compared to the effect of the dry particles alone. The estimated aerosol direct radiative forcings for both, marine and continentally influenced air masses were negative indicating a net cooling of the atmosphere due to the aerosol. The radiative forcing ?Fr was, nevertheless, dominated by the total aerosol concentration most of the time: ?Fr was typically more negative for continentally influenced aerosols (ca. -4 W m-2) compared to rather clean marine aerosols (ca. -1.5 W m-2). When RH occasionally reached 90% in marine air, ?Fr even reached values down to -7 W m-2. Our results emphasize, on the basis of explicit particle hygroscopicity measurements, the relevance of ambient relative humidity for the radiative forcing of regional atmospheres.

  5. Solar fine scale structures in the corona, transition region, and lower atmosphere

    NASA Astrophysics Data System (ADS)

    Moses, Dan; Cook, J. W.; Bartoe, J.-D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, J. M.; Harvey, J. W.; Recely, F.; Martin, S. F.; Zirin, H.

    1994-08-01

    The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV 105, HRTS 1600 A spectroheliograms of the Tmin region, and ground-based magnetogram and He I 10830 A images. We examined the relationship of He I 10830 A dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He I dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km/s, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km/s velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events than expected from the results of a previous Spacelab 2 HRTS disk survey. We attribute this at least partly to better spatial resolution with the newer HRTS data. The full-disk X-ray image shows a pattern of dark lanes in quiet Sun areas. The number density of C IV events is twice as large inside as outside a dark lane (4.6 x 10-3 vs. 2.3 x 10-3 explosive events per arcsec 2). The dark lane corresponds to an old decaying magnetic neutral line. We suggest that this provides an increased opportunity for small-scale convergence and reconnection of opposite polarity magnetic field features, in analogy with the results of Webb et al. for XBPs but at a reduced scale of reconnection.

  6. Solar fine scale structures in the corona, transition region, and lower atmosphere

    NASA Technical Reports Server (NTRS)

    Moses, Dan; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, J. M.; Harvey, J. W.; Realy, F.; Martin, S. F.

    1994-01-01

    The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV 10(exp 5), HRTS 1600 A spectroheliograms of the T(sub min) region, and ground-based magnetogram and He I 10830 A images. We examined the relationship of He I 10830 A dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He I dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km/s, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km/s velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events than expected from the results of a previous Spacelab 2 HRTS disk survey. We attribute this at least partly to better spatial resolution with the newer HRTS data. The full-disk X-ray image shows a pattern of dark lanes in quiet Sun areas. The number density of C IV events is twice as large inside as outside a dark lane (4.6 x 10(exp -3) vs. 2.3 x 10(exp -3) explosive events per arcsec (exp 2)). The dark lane corresponds to an old decaying magnetic neutral line. We suggest that this provides an increased opportunity for small-scale convergence and reconnection of opposite polarity magnetic field features, in analogy with the results of Webb et al. for XBPs but at a reduced scale of reconnection.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  8. Atmospheric BTEX concentrations in the vicinity of the crude oil refinery of the Baltic region.

    PubMed

    Baltr?nas, Pranas; Baltr?nait?, Edita; Serevi?ien?, Vaida; Pereira, Paulo

    2011-11-01

    Among chemical industries, petroleum refineries have been identified as large emitters of a wide variety of pollutants. Benzene, toluene, ethylbenzene, and xylene (BTEX) form an important group of aromatic volatile organic compounds (VOCs) because of their role in the troposphere chemistry and the risk posed to human health. A very large crude oil refinery of the Baltic States (200,000 bbl/day) is situated in the northern, rural part of Lithuania, 10 km from the town of Mažeikiai (Lithuania). The objectives of this study were: (1) to determine of atmospheric levels of BTEX in the region rural and urban parts at the vicinity of the crude oil refinery; and (2) to investigate the effect of meteorological parameters (wind speed, wind direction, temperature, pressure, humidity) on the concentrations measured. The averaged concentration of benzene varied from 2.12 ppbv in the rural areas to 2.75 ppbv in the urban areas where the traffic was determined to be a dominant source of BTEX emissions. Our study showed that concentration of benzene, as strictly regulated air pollutant by EU Directive 2008/50/EC, did not exceed the limit of 5 ppbv in the region in the vicinity of the crude oil refinery during the investigated period. No significant change in air quality in the vicinity of the oil refinery was discovered, however, an impact of the industry on the background air quality was detected. The T/B ratio (0.50-0.81) that was much lower than 2.0, identified other sources of pollution than traffic. PMID:21243423

  9. Future atmospheric abundances and climate forcings from scenarios of global and regional hydrofluorocarbon (HFC) emissions

    NASA Astrophysics Data System (ADS)

    Velders, Guus J. M.; Fahey, David W.; Daniel, John S.; Andersen, Stephen O.; McFarland, Mack

    2015-12-01

    Hydrofluorocarbons (HFCs) are manufactured for use as substitutes for ozone-depleting substances that are being phased out globally under Montreal Protocol regulations. While HFCs do not deplete ozone, many are potent greenhouse gases that contribute to climate change. Here, new global scenarios show that baseline emissions of HFCs could reach 4.0-5.3 GtCO2-eq yr-1 in 2050. The new baseline (or business-as-usual) scenarios are formulated for 10 HFC compounds, 11 geographic regions, and 13 use categories. The scenarios rely on detailed data reported by countries to the United Nations; projections of gross domestic product and population; and recent observations of HFC atmospheric abundances. In the baseline scenarios, by 2050 China (31%), India and the rest of Asia (23%), the Middle East and northern Africa (11%), and the USA (10%) are the principal source regions for global HFC emissions; and refrigeration (40-58%) and stationary air conditioning (21-40%) are the major use sectors. The corresponding radiative forcing could reach 0.22-0.25 W m-2 in 2050, which would be 12-24% of the increase from business-as-usual CO2 emissions from 2015 to 2050. National regulations to limit HFC use have already been adopted in the European Union, Japan and USA, and proposals have been submitted to amend the Montreal Protocol to substantially reduce growth in HFC use. Calculated baseline emissions are reduced by 90% in 2050 by implementing the North America Montreal Protocol amendment proposal. Global adoption of technologies required to meet national regulations would be sufficient to reduce 2050 baseline HFC consumption by more than 50% of that achieved with the North America proposal for most developed and developing countries.

  10. Air-Sea Fluxes Over the Gulf Stream Region: Atmospheric Controls and Trends Jeffrey Shaman, R. M. Samelson, Eric Skyllingstad

    E-print Network

    Kurapov, Alexander

    over the North American eastern seaboard and Labrador Sea and warmer temperatures over the Sargasso Sea the upper water column in the northwestern Sargasso Sea, is defined by its relatively homogeneous1 Air-Sea Fluxes Over the Gulf Stream Region: Atmospheric Controls and Trends Jeffrey Shaman, R. M

  11. Up-gully flow in the great plains region: A mechanism for perturbing the nighttime lower atmosphere?

    E-print Network

    Vadas, Sharon

    Up-gully flow in the great plains region: A mechanism for perturbing the nighttime lower atmosphere during CASES-99 show that when the near-surface nighttime wind direction shifts through the ``up-gully'' direction of a significant gully near the tower, the flow produces a pronounced but localized upward surge

  12. The Impact of LandAtmosphere Interactions on the Temporal Variability of Soil Moisture at the Regional Scale

    E-print Network

    Ramírez, Jorge A.

    The Impact of Land­Atmosphere Interactions on the Temporal Variability of Soil Moisture This study examines the impact of the nonlinear dynamics of soil-moisture feedbacks to precipitation on the temporal variability of soil moisture at the regional scale. It is a modeling study in which the large

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

    NASA Technical Reports Server (NTRS)

    Case, Jonathan

    2001-01-01

    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.

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

    USGS Publications Warehouse

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

    2007-01-01

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

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

    PubMed

    Lee, Pius; Liu, Yang

    2014-12-01

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

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

    PubMed

    Lee, Pius; Liu, Yang

    2014-01-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Case, Jonathan

    2000-01-01

    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.

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

    PubMed Central

    Lee, Pius; Liu, Yang

    2014-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  2. Influence of Past Changes in Atmospheric CO2 on Boron/Calcium of Planktic Fossil Foraminifera

    NASA Astrophysics Data System (ADS)

    Domeyko, R. A.; Allen, K. A.; deMenocal, P. B.

    2014-12-01

    Culture experiments have revealed that B/Ca of shells grown by the foraminiferal species Globigerinoides ruber increase with increasing seawater pH. Specifically, B/Ca responds to changes in the relative abundance of pH-sensitive dissolved carbon and boron species (Allen et al. 2011, 2012). Here, we present a high-resolution study on fossilized G. ruber from two sites in North Atlantic subtropical gyres (VM25-21 and ODP 1055B) through 20 ka BP to evaluate how B/Ca responds to past changes in atmospheric CO2. Forams were picked and crushed gently, then cleaned and dissolved using a variation of the Boyle and Keigwin (1985) and Barker et al. (2003) cleaning protocols prior to analysis. ODP 1055B (from Carolina Slope, West Atlantic) produced a high-resolution record with lower B/Ca values during the glacial period followed by a rapid shift to higher B/Ca values in the early deglaciation, with values remaining high through the Holocene. These results were not predicted by culture calibrations, but they are consistent with B/Ca records from the Caribbean (ODP 999, Foster et al. 2008), suggesting this pattern is characteristic of surface waters in the greater North Atlantic region.

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

    NASA Astrophysics Data System (ADS)

    Breil, Marcus; Panitz, Hans-Jürgen

    2014-05-01

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

  4. Attribution of cyclogenesis region sea surface temperature change to anthropogenic influence

    NASA Astrophysics Data System (ADS)

    Gillett, N. P.; Stott, P. A.; Santer, B. D.

    2008-05-01

    Previous research has identified links between tropical cyclone activity and sea surface temperatures in the tropical cyclogenesis regions of the North Atlantic and Western North Pacific. Other work has demonstrated that warming in these regions is inconsistent with simulated internal variability. After evaluating the variability of a suite of climate models on a range of timescales, we use detection and attribution methods and a suite of 20th century simulations including anthropogenic and natural forcing to identify a significant response to external forcing in both regions during the June-November hurricane season over the 20th century. We then use separate simulations of the response to natural and anthropogenic forcing to identify anthropogenic influence independently of natural influence in both the Atlantic and Pacific Cyclogenesis Regions.

  5. A Regional Atmospheric Continuous CO2 Network In The Rocky Mountains (Rocky RACCOON)

    NASA Astrophysics Data System (ADS)

    Stephens, B.; de Wekker, S.; Watt, A.; Schimel, D.

    2005-12-01

    We have established a continuous CO2 observing network in the Rocky Mountains, building on technological and modeling advances made during the Carbon in the Mountains Experiment (CME), to improve our understanding of regional carbon fluxes and to fill key gaps in the North American Carbon Program (NACP). We will present a description of the Rocky RACCOON network and early results from the first three sites. There are strong scientific and societal motivations for determining CO2 exchanges on regional scales. NACP aims to address these concerns through a dramatic expansion in observations and modeling capabilities over North America. Mountain forests in particular represent a significant potential net CO2 sink in the U.S. and are highly sensitive to land-use practices and climate change. However, plans for new continuous CO2 observing sites have omitted the mountain west. This resulted from expensive instrumentation in the face of limited resources, and a perception that current atmospheric transport models are not sophisticated enough to interpret CO2 measurements made in complex terrain. Through our efforts in CME, we have a new autonomous, inexpensive, and robust CO2 analysis system and are developing mountain CO2 modeling tools that will help us to overcome these obstacles. Preliminary observational and modeling results give us confidence that continuous CO2 observations from mountain top observatories will provide useful constraints on regional carbon cycling and will be valuable in the continental inverse modeling efforts planned for NACP. We began at three Colorado sites in August 2005 and hope to add three to six sites in other western states in subsequent years, utilizing existing observatories to the maximum extent possible. The first three sites are at Niwot Ridge, allowing us to have an ongoing intercomparison with flask measurements made by NOAA CMDL; at Storm Peak Laboratory near Steamboat Springs, allowing us to investigate comparisons between these two relatively nearby sites; and at Fraser Experimental Forest, allowing us to investigate nocturnal respiration rates across a large intermountain valley. Our data are available to the public on the internet in near real time to support quality control, local science, and larger scale synthesis efforts.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  7. Influence of vegetation and seasonal forcing on carbon dioxide fluxes across the Upper Midwest, USA: Implications for regional scaling

    SciTech Connect

    Desai, Desai Ankur R.; Noormets, Asko; Bolstad, Paul V; Chen, Jiquan; Cook, Bruce D; Davis, Kenneth; Euskirchen, Eugenie S; Gough, Christopher M; Martin, Jonathan G; Ricciuto, Daniel M; Schmid, Hans Peter; Tang, Jianwu; Wang, Weiguo

    2008-01-01

    Carbon dioxide fluxes were examined over the growing seasons of 2002 and 2003 from 14 different sites in Upper Midwest (USA) to assess spatial variability of ecosystem atmosphere CO2 exchange. These sites were exposed to similar temperature/precipitation regimes and spanned a range of vegetation types typical of the region (northern hardwood, mixed forest, red pine, jack pine, pine barrens and shrub wetland). The hardwood and red pine sites also spanned a range of stand ages (young, intermediate, mature). While seasonal changes in net ecosystem exchange (NEE) and photosynthetic parameters were coherent across the 2 years at most sites, changes in ecosystem respiration (ER) and gross ecosystem production (GEP) were not. Canopy height and vegetation type were important variables for explaining spatial variability of CO2 fluxes across the region. Light-use efficiency (LUE) was not as strongly correlated to GEP as maximum assimilation capacity (Amax). A bottom-up multi-tower land cover aggregated scaling of CO2 flux to a 2000 km2 regional flux estimate found June to August 2003 NEE, ER and GEP to be 290 89, 408, 48, and 698, 73 gC m-2, respectively. Aggregated NEE, ER and GEP were 280% larger, 32% smaller and 3% larger, respectively, than that observed from a regionally integrating 447m tall flux tower. However, when the tall tower fluxes were decomposed using a footprint-weighted influence function and then reaggregated to a regional estimate, the resulting NEE, ER and GEP were within 11% of the multi-tower aggregation. Excluding wetland and young stand age sites from the aggregation worsened the comparison to observed fluxes. These results provide insight on the range of spatial sampling, replication, measurement error and land cover accuracy needed for multi-tiered bottom-up scaling of CO2 fluxes in heterogeneous regions such as the Upper Midwest, USA.

  8. Micro pulse Lidar Observations of aerosol profiles over urban region of Hyderabad - Influence of Agricultural Crop Residue Burning

    NASA Astrophysics Data System (ADS)

    Kharol, Shailesh Kumar; Badarinath, Kvs; Sharma, Anu Rani; Mahalakshmi, D. V.; K., Sujatha; Yellapragada, Bhavani Kumar

    Aerosols from biomass burning modify cloud microphysical properties and cloud lifetime through the so-called "indirect effect." In the absence of wet scavenging processes, aerosols stay suspended for days to weeks and can be transported to considerable distances. Biomass burning from forest regions and agriculture crop residues can emit substantial amounts of particulate matter and other pollutants into the atmosphere. Results from the Southern African Regional Science Initiative (SAFARI) 2000 dry season field campaign often revealed the presence of an elevated biomass-burning aerosol layer above a semi-permanent stratiform cloud deck off the southern African coasts. An inventory of forest, grassland and agricultural burning is important for studies related to global change. This study provides an account of the agriculture crop residue burning over Indian region and its influence on the columnar aerosol loading over urban region of Hyderabad. Boundary Layer Lidar System fabricated by NARL was used to study the variations in vertical profiles of aerosols during October, 2007 at Hyderabad. The variations in aerosol vertical profiles from Lidar data correlated with sunphotometer observations on aerosol optical depth, black carbon mass concentrations and single scattering albedo estimated from PREDE skyradiomter. The analysis of satellite data sets suggested agricultural crop residue burning towards north of the observations site. The LIDAR profiles revealed the existence of important quantities of aerosols at altitudes between 1200 and 1800m over the city. Three dimensional 120-hours air mass back-trajectory analysis showed that the aerosols detected at the higher altitudes might have originated from agriculture crop residue burning activities taking place at the northern regions. Conjunctive analysis of satellite data together with ground observations provides a means for understanding source regions of aerosols. The results are discussed in the paper.

  9. Model Atmospheres of Irradiated Exoplanets: The Influence of Stellar Parameters, Metallicity, and the C/O Ratio

    NASA Astrophysics Data System (ADS)

    Mollière, P.; van Boekel, R.; Dullemond, C.; Henning, Th.; Mordasini, C.

    2015-11-01

    Many parameters constraining the spectral appearance of exoplanets are still poorly understood. We therefore study the properties of irradiated exoplanet atmospheres over a wide parameter range including metallicity, C/O ratio, and host spectral type. We calculate a grid of 1D radiative-convective atmospheres and emission spectra. We perform the calculations with our new Pressure–Temperature Iterator and Spectral Emission Calculator for Planetary Atmospheres (PETIT) code, assuming chemical equilibrium. The atmospheric structures and spectra are made available online. We find that atmospheres of planets with C/O ratios ?1 and {T}{{eff}} ? 1500 K can exhibit inversions due to heating by the alkalis because the main coolants CH4, H2O, and HCN are depleted. Therefore, temperature inversions possibly occur without the presence of additional absorbers like TiO and VO. At low temperatures we find that the pressure level of the photosphere strongly influences whether the atmospheric opacity is dominated by either water (for low C/O) or methane (for high C/O), or both (regardless of the C/O). For hot, carbon-rich objects this pressure level governs whether the atmosphere is dominated by methane or HCN. Further we find that host stars of late spectral type lead to planetary atmospheres which have shallower, more isothermal temperature profiles. In agreement with prior work we find that for planets with {T}{{eff}}\\lt 1750 K the transition between water or methane dominated spectra occurs at C/O ? 0.7, instead of ?1, because condensation preferentially removes oxygen.

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

    E-print Network

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

    2005-10-14

    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.

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

    NASA Astrophysics Data System (ADS)

    Nordmann, S.; Cheng, Y. F.; Carmichael, G. R.; Yu, M.; Denier van der Gon, H. A. C.; Zhang, Q.; Saide, P. E.; Pöschl, U.; Su, H.; Birmili, W.; Wiedensohler, A.

    2014-06-01

    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 BC particles over Central Europe, the model WRF-Chem was used at a resolution of 12 km in conjunction with a high resolution BC emission inventory (EUCAARI 42-Pan-European Carbonaceous Aerosol Inventory; 1/8° × 1/16°). The model simulation was evaluated using measurements of equivalent soot carbon, absorption coefficients and particle number concentrations at 7 sites within the German Ultrafine Aerosol Network, PM10 mass concentrations from the dense measurement network of the German Federal Environmental Agency at 392 monitoring stations, and aerosol optical depth from MODIS and AERONET. A distinct time period (25 March to 10 April 2009) was chosen, during which the clean marine air mass prevailed in the first week and afterwards the polluted continental air mass mainly from south-east dominated with elevated daily average BC concentration up to 4 ?g m-3. The simulated PM10 mass concentration, aerosol number concentration and optical depth were in a good agreement with the observations, while the modelled BC mass concentrations were found to be a factor of 2 lower than the observations. Together with backtrajectories, detailed model bias analyses suggested that the current BC emission in countries to the east and south of Germany might be underestimated by a factor of 5, at least for the simulation period. Running the model with upscaled BC emissions in these regions led to a smaller model bias and a better correlation between model and measurement. On the contrary, the particle absorption coefficient was positively biased by about 20% even when the BC mass concentration was underestimated by around 50%. This indicates that the internal mixture treatment of BC in the WRF-Chem optical calculation is unrealistic in our case, which over amplifies the light absorption by BC containing particles. By adjusting the modeled mass absorption cross-section towards the measured values, the simulation of particle light absorption of BC was improved as well. Finally, the positive direct radiative forcing of BC particles at top of the atmosphere was estimated to be in the range of 0 to +4 W m-2 over Germany for the model run with improved BC mass concentration and adjusted BC light absorption cross-section. This treatment lowered the positive forcing of BC by up to 70%, compared with the internal mixing treatment of BC in the model simulation.

  12. Atmospheric black carbon and warming effects influenced by the source and absorption enhancement in central Europe

    NASA Astrophysics Data System (ADS)

    Nordmann, S.; Cheng, Y. F.; Carmichael, G. R.; Yu, M.; Denier van der Gon, H. A. C.; Zhang, Q.; Saide, P. E.; Pöschl, U.; Su, H.; Birmili, W.; Wiedensohler, A.

    2014-12-01

    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 BC particles over central Europe, the model WRF-Chem was used at a resolution of 12 km in conjunction with a high-resolution BC emission inventory (EUCAARI 42-Pan-European Carbonaceous Aerosol Inventory; 1/8° × 1/16°). The model simulation was evaluated using measurements of equivalent soot carbon, absorption coefficients and particle number concentrations at seven sites within the German Ultrafine Aerosol Network, PMregions led to a smaller model bias and a better correlation between model and measurement. In contrast, the particle absorption coefficient was positively biased by about 20% even when the BC mass concentration was underestimated by around 50%. This indicates that the internal mixture treatment of BC in the WRF-Chem optical calculation is unrealistic in our case, which overamplifies the light absorption by BC-containing particles. By adjusting the modelled mass absorption cross-section towards the measured values, the simulation of particle light absorption of BC was improved as well. Finally, the positive direct radiative forcing of BC particles at the top of the atmosphere was estimated to be in the range of 0 to +4 W m-2 over Germany for the model run with improved BC mass concentration and adjusted BC light absorption cross-section. This adjustment lowered the positive forcing of BC by up to 70%, compared with the internal mixing treatment of BC in the model simulation.

  13. Influence of regional climate change on meteorological characteristics and their subsequent effect on ozone dispersion in Taiwan

    NASA Astrophysics Data System (ADS)

    Cheng, Fang-Yi; Jian, Shan-Ping; Yang, Zhih-Min; Yen, Ming-Cheng; Tsuang, Ben-Jei

    2015-02-01

    The objective of this study is to understand the influence of regional climate change on local meteorological conditions and their subsequent effect on local ozone (O3) dispersion in Taiwan. The 33-year NCEP-DOE Reanalysis 2 (NNR2) data set (1979-2011) was analyzed to understand the variations in regional-scale atmospheric conditions in East Asia and the western North Pacific. To save computational processing time, two scenarios representative of past (1979-86) and current (2004-11) atmospheric conditions were selected but only targeting the autumn season (September, October and November) when the O3 concentrations were at high levels. Numerical simulations were performed using weather research and forecasting (WRF) model and Community Multiscale Air Quality (CMAQ) model for the past and current scenarios individually but only for the month of October because of limited computational resources. Analysis of NNR2 data exhibited increased air temperature, weakened Asian continental anticyclone, enhanced northeasterly monsoonal flow, and a deepened low-pressure system forming near Taiwan. With enhanced evaporation from oceans along with a deepened low-pressure system, precipitation amounts increased in Taiwan in the current scenario. As demonstrated in the WRF simulation, the land surface physical process responded to the enhanced precipitation resulting in damper soil conditions, and reduced ground temperatures that in turn restricted the development of boundary layer height. The weakened land-sea breeze flow was simulated in the current scenario. With reduced dispersion capability, air pollutants would tend to accumulate near the emission source leading to a degradation of air quality in this region. The conditions would be even worse in southwestern Taiwan due to the fact that stagnant wind fields would occur more frequently in the current scenario. On the other hand, in northern Taiwan, the simulated O3 concentrations are lower during the day in the current scenario due to the enhanced cloud conditions and reduced solar radiation.

  14. Response of atmosphere circulation on global and regional scales to the two El Niño flavors

    NASA Astrophysics Data System (ADS)

    Zheleznova, Irina; Gushchina, Daria

    2015-04-01

    El Niño - Southern Oscillation (ENSO) is one of the most striking anomalies in the climate system of our planet. Recently it has been established [Ashok et al., 2007; Kug et al., 2009] that El Niño appears in two different flavors: the canonical El Niño, which is characterized by the maximum SST anomalies in the eastern Pacific, and El Niño Modoki with maximum anomalies localized in the center of the Pacific Ocean, near the date line. Recent studies demonstrated [Ashok et al., 2007; Weng et al., 2009; Mo, 2010 et al.] that the remote response to the two types of El Niño is drastically different, being opposite in some areas. Based on the regression analysis the air temperature and precipitation anomalies observed during canonical and Modoki El Niño were defined. However, the structure and mechanisms of this response are fairly understood. A comprehensive analysis of the atmospheric circulation anomalies resulted from two types of El Niño may emerge the causes of different remote response associated to the two types of El Niño. The large-scale zonal atmospheric circulation response to El Niño is characterized by the poleward propagation of the signal from the equatorial and tropical latitudes. El Niño is associated with the intensification of western currents in mid latitudes and equatorial belt in the low troposphere and decreasing of the easterlies in tropics. The global circulation response is more intensive during El Niño Modoki as compare to the canonical El Niño. However, the spatial structure of the response is similar for the both types of El Niño. El Niño induces drastic anomalies in vertical circulation. It is shown that Hadley and Walker circulation anomalies associated to the Canonical and Modoki El Niño have different space localization and timing. Canonical El Niño is characterized by anomalous ascending motion in central and eastern Pacific localized near the equator and in the equatorial regions of the Southern Hemisphere. Over Indonesia, south to the equator prevails air descent. During El Niño Modoki anomalous air rising occurs over the central equatorial Pacific, while descending motion develop to the east (mainly in the equatorial regions of the Southern Hemisphere) and to the west (in the Northern Hemisphere). The structure of the anomalies of vertical cells outside the Pacific region differ over the Western Indian Ocean and East Africa, South America and the Caribbean. The analysis of regional circulation response to the El Niño revealed that in the Northern Hemisphere the intensity of the response is comparable for two types of El Niño, while in the Southern Hemisphere the circulation anomalies are more pronounced during the El Niño Modoki. All atmosphere centers of actions under investigation were divided into four groups according to the character of circulation response to the two types of El Niño: 1 - centers of action with similar response to both types of El Niño; 2 - centers of action with different response to canonical and Modoki El Niño; 3 - centers of action, having significant correlations with only one type of El Niño; 4 - centers of action with no significant relationships with two types of El Niño. It is suggested that the difference in weather anomalies observed during the two types of El Niño are mostly associated to the circulation anomalies in the centers of action and in the vertical cells which differs between canonical and Modoki El Niño. References: 1. Ashok K., Behera S. K., Rao S. A., Weng H., Yamagata, T. El Nino Modoki and its possible teleconnection. J. Geophys. Res. 2007, 112, C11007, doi:10.1029/2006JC003798. 2. Kug, J.S., Jin F.F. and An S.I. Two types of El Niño events:Cold tongue El Niño and warm pool El Niño. // J. Clim., 2009, vol. 22, pp. 1499-1515. 3. Mo, K. C., Interdecadal modulation of the impact of ENSO on precipitation and temperature over the United States, J. Clim., 2010, 23, 3639-3656, doi:10.1175/2010JCLI3553.1. 4. Weng H., Behera S. K. and Yamagata T. Anomalous winter climate conditions in the Pacific Rim during recent El N

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  16. Influence of Asteroid and Comet Impacts on Atmospheric Abundances at Venus, Earth, and Mars

    NASA Astrophysics Data System (ADS)

    Heath, Caitlin; Brain, D. A.

    2013-10-01

    Asteroid and comet impacts have undoubtedly altered the atmospheres of the terrestrial planets over billions of years. Impacts are capable of either delivering or removing atmospheric particles from a planet depending upon the characteristics of the impact. With many thousands of impacts large enough to alter the atmospheres of each terrestrial planet, all with varying compositions, velocities, impact angles, and sizes, it is not entirely clear how impacts have contributed to changes in atmospheric abundance over time. Some theoretical and numerical work has been undertaken in the past for generic individual impacts, and several studies have considered the net effect of impacts on the atmospheres of Mars and Earth over time. However, the full parameter space of atmospheric impact calculations remains unexplored, particularly in regards to Venus and the effect of oblique impacts on atmospheres. This work uses Monte Carlo simulations to model atmospheric erosion and delivery from impacts at Venus, Earth, and Mars. Flexibility in the code allows us to examine the effects of changing impactor populations (i.e. size and composition), velocity distributions, and angles of impact on the resultant atmospheric pressure, as well as the different sensitivities to these factors between the planets. The work we present relies on published analytic expressions for the effects of individual impacts. However, the results of detailed simulations of individual impacts (e.g. using the RAGE hydrocode) can be incorporated into our future modeling efforts to help validate these expressions.

  17. Influence of the voltage polarity on the properties of a nanosecond surface barrier discharge in atmospheric-pressure air

    SciTech Connect

    Nudnova, M. M.; Aleksandrov, N. L.; Starikovskii, A. Yu.

    2010-01-15

    The properties of a surface barrier discharge in atmospheric-pressure air at different polarities of applied voltage were studied experimentally. The influence of the voltage polarity on the spatial structure of the discharge and the electric field in the discharge plasma was determined by means of spectroscopic measurements. It is found that the energy deposited in the discharge does not depend on the voltage polarity and that discharges of positive polarity are more homogenous and the electric fields in them are higher.

  18. An analysis of region-of-influence methods for flood regionalization in the Gulf-Atlantic Rolling Plains

    USGS Publications Warehouse

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

    2005-01-01

    Region-of-influence (RoI) approaches for estimating streamflow characteristics at ungaged sites were applied and evaluated in a case study of the 50-year peak discharge in the Gulf-Atlantic Rolling Plains of the southeastern United States. Linear regression against basin characteristics was performed for each ungaged site considered based on data from a region of influence containing the n closest gages in predictor variable (PRoI) or geographic (GRoI) space. Augmentation of this count based cutoff by a distance based cutoff also was considered. Prediction errors were evaluated for an independent (split-sampled) dataset. For the dataset and metrics considered here: (1) for either PRoI or GRoI, optimal results were found when the simpler count based cutoff, rather than the distance augmented cutoff, was used; (2) GRoI produced lower error than PRoI when applied indiscriminately over the entire study region; (3) PRoI performance improved considerably when RoI was restricted to predefined geographic subregions.

  19. Simulating summertime rainfall variability in the North American monsoon region: The influence of convection and radiation

    E-print Network

    Small, Eric

    Simulating summertime rainfall variability in the North American monsoon region: The influence of the North American Monsoon System (NAMS) is essential for understanding and assessing the predictability with monsoon onset (June to July) and changes between a wet (1999) and a dry (2000) year. We test six

  20. Influence of regional development policies and clean technology adoption on future air pollution exposure

    E-print Network

    Handy, Susan L.

    Influence of regional development policies and clean technology adoption on future air pollution pollution emissions in the year 2030 were estimated for the San Joaquin Valley (SJV) in central California using a combined system of land use, mobile, off-road, stationary, area, and biogenic emissions models

  1. INFLUENCE OF BED-REGION STOICHIOMETRY ON NITRIC OXIDE FORMATION IN FIXED-BED COAL COMBUSTION

    EPA Science Inventory

    The article describes the use of a 15.3 x 25.4 cm thick bed reactor with refractory walls to investigate the influence of bed-region (first-stage) stoichiometry on fuel nitrogen evolution and reaction in coal-fired mass-burning stokers. The combustor operated in a batch mode prov...

  2. Global, Regional and Local Influences on Adult Literacy Policy in England

    ERIC Educational Resources Information Center

    Hamilton, Mary

    2014-01-01

    This paper explores the relationship between global, regional and local influences on adult literacy policy and practice in the UK through a discourse analysis of policy-related texts. The analysis is framed by theoretical perspectives from literacy studies and socio-material theory. The paper identifies a number of specific features in the UK…

  3. PRELIMINARY ASSESSMENTS OF SPATIAL INFLUENCES IN THE AMBOS NOGALES REGION OF THE US-MEXICAN BORDER

    EPA Science Inventory

    Ambient air measurements collected from 1994 to 1995 were used in a preliminary assessment of potential source and spatial influences in the Ambos Nogales border region (Nogales, Arizona, USA and Nogales, Sonora, Mexico). In this assessment, volatile organic compounds (VOC) and...

  4. EVIDENCE FOR WIDESPREAD COOLING IN AN ACTIVE REGION OBSERVED WITH THE SDO ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Viall, Nicholeen M.; Klimchuk, James A.

    2012-07-01

    A well-known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions (ARs). Is this cooling pattern a common property of AR coronal plasma, or does it only occur in unique circumstances, locations, and times? The new Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data provide a wonderful opportunity to answer this question systematically for an entire AR. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hr of images of AR 11082 observed on 2010 June 19. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the AR including the diffuse emission between loops for the entire 24 hr duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hr time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than {approx}0.8 MK. This suggests that the bulk of the emitting coronal plasma in this AR is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

  5. Regional Climate Downscaling Using a High-resolution Global Atmospheric Model

    NASA Astrophysics Data System (ADS)

    Kunhu Bangalath, Hamza; Stenchikov, Georgiy; Osipov, Sergey

    2013-04-01

    In this study, we used HIRAM, a high-resolution atmospheric model [Zhao et al., 2009] for climate downscaling with the horizontal grid spacing of 25 km. Our simulations followed the CORDEX protocol [Giorgi et al., 2009] and were conducted for historic (1975-2006) and future (2005-2050) periods using both RCP 4.5 and RCP 8.5 scenarios. Compared with the Geophysical Fluid Dynamics Laboratory (GFDL) AM2.0 and AM2.1 [Delworth et al., 2006], HIRAM uses enhanced vertical discretization on 32 vertical layers instead of 24 and replaces the relaxed Arakawa-Schubert convective closure with the one developed at the University of Washington. The model retains the surface flux, boundary layer, large-scale cloud microphysics, and radiative transfer modules from the AM2 family [Delworth et al., 2006]. HIRAM also employs a cubed-sphere implementation (here at 25-km resolution) of a finite-volume dynamical core and is coupled to LM3, a new land model with ecosystem dynamics and hydrology. In our simulations, the Sea Surface Temperatures (SSTs) from the GFDL Earth System Model runs, ESM2M and ESM2G, performed for the International Panel for Climate Change AR5 project with a latitude-longitude grid of 2°x2.5° were adopted as the bottom boundary conditions over the sea. We used prescribed time-varying greenhouse gas and stratospheric/tropospheric aerosol distribution datasets to reproduce the observed radiative forcing in the model as described by Delworth et al. [2006]. Here, we present results for the CORDEX Middle East and North Africa domain and compared them with the coarse-resolution ESM2M/ESM2G simulations as well as with the nested regional model projections. Delworth, T. et al. (2006), GFDL's CM2 Global Coupled Models. Part I: Formulation and Simulation Characteristics, J. Climate, 19, 643-674. Giorgi, F., C. Jones, and G. Asrar (2009), Addressing climate information needs at the regional level: The CORDEX framework. WMO Bull., 58, 175-183 Zhao, M., I. M. Held, S-J. Lin, and G.A. Vecchi (2009), Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50km Resolution GCM, J. Climate, 33, 6653-6678.

  6. Influence of modified atmosphere packaging on the shelf life of prebaked pizza dough with and without preservative added.

    PubMed

    Rodríguez, Valle; Medina, Luis; Jordano, Rafael

    2003-04-01

    The possible effect of different modified atmospheres on the shelf life of prebaked pizza dough, with and without added calcium propionate, was investigated. Three packaging atmospheres were tested: 20% CO2: 80% N2, 50% CO2: 50% N2, 100% CO2, and air (control). Samples were examined daily for visible mold growth and analysed after 2, 8, 17 and 31 days throughout storage (15-20 degrees C and 54-65% relative humidity, RH) for changes in gaseous composition, pH and microbial populations (mesophilic aerobic and anaerobic bacteria, lactic acid bacteria (LAB), and yeasts and molds). Microbiological results showed that molds had a greater sensitivity to CO2 than bacteria and yeasts. Products containing calcium propionate did not show mold growth throughout storage (31 days) when packaged in air or in CO2-enriched atmospheres (20, 50 and 100%). However, in pizza dough without preservative (calcium propionate), mold growth was evident after 7 days, except under 100% CO2 atmosphere (13 days) regardless of the packaging atmosphere. From these results we conclude that the addition of calcium propionate had more and decisive influence on the shelf life extension of prebaked pizza dough. PMID:12744291

  7. Atmospheric Response in Aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    NASA Astrophysics Data System (ADS)

    Larsen, M. F.; Marshall, T. R.; Mikkelsen, I. S.; Emery, B. A.; Christensen, A.; Kayser, D.; Hecht, J.; Lyons, L.; Walterscheid, R.

    1995-09-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the postmidnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of ~100 ms-1 developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of ~150 ms-1 developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of ~0.08.

  8. Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    SciTech Connect

    Larsen, M.F.; Marshall, T.R.; Mikkelsen, I.S.; Emery, B.A.; Christensen, A.; Kayser, D.; Hecht, J.; Lyons, L.; Walterscheid, R.

    1995-11-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the post midnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. The authors focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of approximately 100 m/s developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of approximately 150 m/s developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of approximately 0.08.

  9. Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    SciTech Connect

    Larsen, M.F.; Marshall, T.R.; Mikkelsen, I.S.

    1995-09-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the postmidnight sector. A combination of chemical release rocket wind measurements, intrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of {approximately}100 m s{sup -1} developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of {approximately}150 m s{sup -1} developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nomially unstable with a Richardson number of {approximately}0.08. 17 refs., 12 figs.

  10. Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    NASA Technical Reports Server (NTRS)

    Larsen, M. F.; Marshall, T. R.; Mikkelsen, I. S.; Emery, B. A.; Christensen, A.; Kayser, D.; Hecht, J.; Lyons, L.; Walterscheid, R.

    1995-01-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the post midnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of approximately 100 m/s developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of approximately 150 m/s developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of approximately 0.08.

  11. The Influence of Hepatitis C Virus Genetic Region on Phylogenetic Clustering Analysis

    PubMed Central

    Lamoury, François M. J.; Jacka, Brendan; Bartlett, Sofia; Bull, Rowena A.; Wong, Arthur; Amin, Janaki; Schinkel, Janke; Poon, Art F.; Matthews, Gail V.; Grebely, Jason; Dore, Gregory J.; Applegate, Tanya L.

    2015-01-01

    Sequencing is important for understanding the molecular epidemiology and viral evolution of hepatitis C virus (HCV) infection. To date, there is little standardisation among sequencing protocols, in-part due to the high genetic diversity that is observed within HCV. This study aimed to develop a novel, practical sequencing protocol that covered both conserved and variable regions of the viral genome and assess the influence of each subregion, sequence concatenation and unrelated reference sequences on phylogenetic clustering analysis. The Core to the hypervariable region 1 (HVR1) of envelope-2 (E2) and non-structural-5B (NS5B) regions of the HCV genome were amplified and sequenced from participants from the Australian Trial in Acute Hepatitis C (ATAHC), a prospective study of the natural history and treatment of recent HCV infection. Phylogenetic trees were constructed using a general time-reversible substitution model and sensitivity analyses were completed for every subregion. Pairwise distance, genetic distance and bootstrap support were computed to assess the impact of HCV region on clustering results as measured by the identification and percentage of participants falling within all clusters, cluster size, average patristic distance, and bootstrap value. The Robinson-Foulds metrics was also used to compare phylogenetic trees among the different HCV regions. Our results demonstrated that the genomic region of HCV analysed influenced phylogenetic tree topology and clustering results. The HCV Core region alone was not suitable for clustering analysis; NS5B concatenation, the inclusion of reference sequences and removal of HVR1 all influenced clustering outcome. The Core-E2 region, which represented the highest genetic diversity and longest sequence length in this study, provides an ideal method for clustering analysis to address a range of molecular epidemiological questions. PMID:26192190

  12. Anthropogenic Influence on Secondary Aerosol Formation and Total Water-Soluble Carbon on Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Gioda, Adriana; Mateus, Vinicius; Monteiro, Isabela; Taira, Fabio; Esteves, Veronica; Saint'Pierre, Tatiana

    2013-04-01

    On a global scale, the atmosphere is an important source of nutrients, as well as pollutants, because of its interfaces with soil and water. Important compounds in the gaseous phase are in both organic and inorganic forms, such as organic acids, nitrogen, sulfur and chloride. In spite of the species in gas form, a huge number of process, anthropogenic and natural, are able to form aerosols, which may be transported over long distances. Sulfates e nitrates are responsible for rain acidity; they may also increase the solubility of organic compounds and metals making them more bioavailable, and also can act as cloud condensation nuclei (CCN). Aerosol samples (PM2.5) were collected in a rural and industrial area in Rio de Janeiro, Brazil, in order to quantify chemical species and evaluate anthropogenic influences in secondary aerosol formation and organic compounds. Samples were collected during 24 h every six days using a high-volume sampler from August 2010 to July 2011. The aerosol mass was determined by Gravimetry. The water-soluble ionic composition (WSIC) was obtained by Ion Chromatography in order to determine the major anions (NO3-, SO4= and Cl-); total water-soluble carbon (TWSC) was determined by a TOC analyzer. The average aerosol (PM2.5) concentrations ranged from 1 to 43 ug/m3 in the industrial site and from 4 to 35 ug/m3 in the rural area. Regarding anions, the highest concentrations were measured for SO42- (10.6 ?g/m3-12.6 ?g/m3); where the lowest value was found in the rural site and the highest in the industrial. The concentrations for NO3- and Cl- ranged from 4.2 ?g/m3 to 9.3 ?g/m3 and 3.1 ?g/m3 to 6.4 ?g /m3, respectively. Sulfate was the major species and, like nitrate, it is related to photooxidation in the atmosphere. Interestingly sulfate concentrations were higher during the dry period and could be related to photochemistry activity. The correlations between nitrate and non-sea-salt sulfate were weak, suggesting different sources for these species. The secondary aerosol represented an important fraction of total compounds in PM2.5 ranged from 16 to 18% for (NH4)2SO4 and 6 to 8% for NH4NO3. The values for TWSC ranged from 0.28 to 6.35 ?g/m3 in the industrial area and 0.12 to 7.49 ?g/m3 for rural area. The similarity between the areas regarding secondary aerosols formation and water-soluble carbon compounds is probably due to the particle size.

  13. A spatially explicit multi-isotope approach to map influence regions of plant-plant interactions after exotic plant invasion

    NASA Astrophysics Data System (ADS)

    Hellmann, Christine; Oldeland, Jens; Werner, Christiane

    2015-04-01

    Exotic plant invasions impose profound alterations to native ecosystems, including changes of water, carbon and nutrient cycles. However, explicitly quantifying these impacts remains a challenge. Stable isotopes, by providing natural tracers of biogeochemical processes, can help to identify and measure such alterations in space and time. Recently, ?15N isoscapes, i.e. spatially continuous representations of isotopic values, derived from native plant foliage, enabled to accurately trace nitrogen introduced by the N2-fixing invasive Acacia longifolia into a native Portuguese dune system. It could be shown that the area of the system which was altered by the invasive species exceeded the area which was covered by the invader by far. But still, definition of clear regions of influence is to some extent ambiguous. Here, we present an approach using multiple isoscapes derived from measured foliar ?13C and ?15N values of a native, non-fixing species, Corema album. By clustering isotopic information, we obtained an objective classification of the study area. Properties and spatial position of clusters could be interpreted to distinguish areas that were or were not influenced by A. longifolia. Spatial clusters at locations where A. longifolia was present had ?15N values that were enriched, i.e. close to the atmospheric signal of 0 o compared to the depleted values of the uninvaded system (ca. -11 o). Furthermore, C. album individuals in these clusters were characterized by higher foliar N content and enriched ?13C. These results indicate that the N2-fixing A. longifolia added nitrogen to the system which originated from the atmosphere and was used by the native C. album, inducing functional changes, i.e. an increase in WUE. Additionally, clusters were identified that were presumably determined by inherent properties of the native system. Thus, combining isotope ecology with geostatistical methods is a promising approach for mapping regions of influence in multi-isotope isoscapes which may be relevant not only to detect ecological boundaries within the context of exotic plant invasion but for plant-plant-interactions and small-scale variability of biotic and abiotic conditions in general.

  14. Influence of Atmospheric Electric Fields on the Radio Emission from Extensive Air Showers

    E-print Network

    Trinh, T N G; Buitink, S; Berg, A M van den; Corstanje, A; Ebert, U; Enriquez, J E; Falcke, H; Hörandel, J R; Köhn, C; Nelles, A; Rachen, J P; Rossetto, L; Rutjes, C; Schellart, P; Thoudam, S; ter Veen, S; de Vries, K D

    2015-01-01

    The atmospheric electric fields in thunderclouds have been shown to significantly modify the intensity and polarization patterns of the radio footprint of cosmic-ray-induced extensive air showers. Simulations indicated a very non-linear dependence of the signal strength in the frequency window of 30-80 MHz on the magnitude of the atmospheric electric field. In this work we present an explanation of this dependence based on Monte-Carlo simulations, supported by arguments based on electron dynamics in air showers and expressed in terms of a simplified model. We show that by extending the frequency window to lower frequencies additional sensitivity to the atmospheric electric field is obtained.

  15. [Influence factors of deposition induced by melt water erosion in Naqu region, China].

    PubMed

    Feng, Jun-yuan; Cai, Qiang-guo; Li, Zhao-xia; Sun, Li-ying

    2015-02-01

    Melt water erosion is one of the important soil erosion forms caused by the melt water from glacier and snow in high altitude cold areas of China. This paper investigated the influencing factors of deposition caused by melt water erosion in Naqu region. Alluvial fan ratio was presented as an index to characterize the degree of the deposition induced by melt water erosion. Minimum polygon was determined based on spatial overlay technology of Geographic Information System (GIS). The regression equation between the deposition index and the influencing factors was established through the stepwise regression analysis based on minimum polygon. Key influencing factors were identified according to the stepwise regression equation. The results showed that large amounts of alluvial fan were observed in Naqu region; extensive alluvial fans were centered at gentle slope areas in the central part of Naqu region with great spatial differences; alluvial fans were mainly distributed at valley exits, most of which were at large scale with vast differences in area and thickness. Wind speed, normalized difference vegetation index (NDVI), K value of soil erodibility, annual temperature range and the steep slope area ratio were identified as the key influencing factors on the deposition induced by melt water erosion in the studied area. Index of deposition was positively correlated with the wind speed and NDVI, and showed negative relationships with the K value of soil erodibility, the annual temperature range and steep slope area ratio. PMID:26094471

  16. Localized Internal Gravity Waves Breaking Region and its Implications for Middle Atmospheric Circulation and Stratosphere-Troposphere Exchange

    NASA Astrophysics Data System (ADS)

    Šácha, Petr; Pišoft, Petr; Kucha?, Aleš; Lilienthal, Friederike; Jacobi, Christoph

    2015-04-01

    Internal gravity waves are widely recognized to contribute significantly to the energy and angular momentum transport. They play significant role in affecting many of the middle atmospheric phenomena (like QBO or Brewer-Dobson circulation). Using the GPS RO density profiles, we have discovered a localized area of enhanced IGW activity and breaking in the lower stratosphere of Eastern Asia/North-western Pacific region. Using a mechanistic model for the middle atmosphere, 3D EP flux and residual circulation diagnostics, we investigate longitudinal variability of the Brewer-Dobson circulation and a hypothesis of its enhanced branch in this region. Further, we study possible formation and propagation directions of planetary waves caused by such a localized forcing and discuss the consequences for the stratosphere-troposphere exchange and polar vortex stability.

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

    E-print Network

    Wei, Jun

    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) ...

  18. Regional terrestrial water storage change and evapotranspiration from terrestrial and atmospheric water balance computations

    E-print Network

    Yeh, Pat J.-F.; Famiglietti, J. S

    2008-01-01

    Long-Term Drift in the Estimated Terrestrial Water Storage [STORAGE AND EVAPOTRANSPIRATION to check the accuracy of atmospheric water balance com- putations is through the comparison between the long-term

  19. Specific protein regions influence substrate specificity and product length in polyunsaturated fatty acid condensing enzymes.

    PubMed

    Vrinten, Patricia L; Hoffman, Travis; Bauer, Jörg; Qiu, Xiao

    2010-05-11

    We describe a condensing enzyme from Pythium irregulare (PirELO) that shows highest activity on the 18-carbon, Delta-6 desaturated fatty acids, stearidonic acid and gamma-linolenic acid. However, this enzyme is also capable of elongating a number of other fatty acids including the 20-carbon, Delta-5 desaturated fatty acid eicosapentaenoic acid. Surprisingly, a Phytophthora infestans condensing enzyme (PinELO) with very high homology to PirELO did not show activity with 20-carbon fatty acids. A series of chimeric proteins for these two enzymes were constructed to investigate the influence of different regions on substrate and product length. The substitution of a region from near the center of PirELO into PinELO resulted in an enzyme having EPA-elongating activity similar to that of PirELO. Only eight amino acids differed between the two proteins in this region; however, substitution of the same region from PinELO into PirELO produced a protein which was almost inactive. The addition of a small region from near the N-terminus of PinELO was sufficient to restore activity with GLA, indicating that amino acids from these two regions interact to determine protein structure or function. Predicted topology models for PirELO and PinELO placed the two regions described here near the luminal-proximal ends of the first and fourth/fifth transmembrane helixes, at the opposite end of the condensing enzyme from four conserved regions thought to form a catalytic ring. Thus, protein characteristics determined by specific luminal-proximal regions of fatty acid condensing enzymes have a major influence on substrate specificity and final product length. PMID:20397628

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

    E-print Network

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

    2010-04-01

    Although soil erosion has often been considered a net source of atmospheric carbon (C), several recent studies suggest that erosion serves as a net C sink. We have developed a spreadsheet?based model of soil organic C ...

  1. Investigations on vertical coupling of atmospheric regions using combined multiwavelength optical dayglow, magnetic, and radio measurements

    NASA Astrophysics Data System (ADS)

    Laskar, Fazlul I.; Pallamraju, Duggirala; Lakshmi, T. Vijaya; Reddy, M. Anji; Pathan, B. M.; Chakrabarti, Supriya

    2013-07-01

    Systematic investigations of optical dayglow emissions at OI 557.7, OI 630.0, and OI 777.4 nm have been carried out simultaneously over a large field of view (~140°). These emission intensities are obtained during January-March in the years 2011 and 2012 from Hyderabad (17.5°N, 78.5°E), India, using a high spectral resolution multiwavelength imaging echelle spectrograph. Spectral analyses of planetary wave type periodicities in all the dayglow emission intensities are performed, and their association with lower atmospheric and direct solar forcings is presented. This analysis revealed that periods near the atmospheric free normal modes of 5, 10, 16, and 25 days (which are produced mainly in the troposphere) are found to register their presence in the upper atmospheric emission intensities. In an earlier study during high solar activity period (2001), sunspot numbers (SSNs) and the daily averaged OI 630.0 nm dayglow intensities were seen to be covarying. In contrast, the variability in the dayglow emission intensities during relatively low solar activity epoch (2011) shows no or weaker correlation with that of the SSN but a greater similarity with that of the equatorial electrojet strength. Periodicities of both lower atmospheric normal modes and those related to sunspots are found during moderate solar activity (2012). Based on this analysis, it appears that the upper atmospheric dayglow emissions respond mainly to lower atmospheric forcing during low solar activity, solar forcing in high solar activity, and both during moderate solar activity level.

  2. Regionalized autosomal STR profiles among Armenian groups suggest disparate genetic influences.

    PubMed

    Lowery, Robert K; Herrera, Kristian J; Barrett, Dianne A; Rodriguez, Rosa; Hadden, Laura R M; Harutyunyan, Ashot; Margaryan, Ashot; Yepiskoposyan, Levon; Herrera, Rene J

    2011-10-01

    The archeology and ethnology of Armenia suggest that this region has acted as a crossroads for human migrations from Europe and the Middle East since at least the Neolithic. Near continual foreign influx has, in turn, led to the supposition that the gene pools of geographically separated Armenian populations may have diverged as differing historical influences potentially left distinct genetic traces in the various regions of the Armenian plateau. In this study, we seek to address whether any evidence for such genetic regional partitioning in Armenians exists by analyzing, for the first time, 15 autosomal short tandem repeat (STR) loci in 404 Armenians from four geographically well-characterized collections (Ararat Valley, Gardman, Sasun, and Lake Van) that represent distinct communities from across Historical Armenia. In addition, to determine whether genetic differences among these four Armenian populations are the result of differential affinities to populations of known historical influence in Armenia, we utilize 27 biogeographically targeted reference populations for phylogenetic and admixture analyses. From these examinations, we find that while close genetic affiliations exist between the two easternmost Armenian groups analyzed, Ararat Valley and Gardman, the remaining two populations display substantial distinctions. In particular, Sasun is distinguished by evidence for genetic contributions from Turkey, while a stronger Balkan component is detected in Lake Van, potentially suggestive of remnant genetic influences from ancient Greek and Phrygian populations in this region. PMID:21826633

  3. The Influence of Shale Rock Fracturing Equipment Operation on Atmospheric Air Quality

    NASA Astrophysics Data System (ADS)

    Bogacki, Marek; Macuda, Jan

    2014-12-01

    The hydraulic fracturing jobs performed on shale rocks are connected with atmospheric emissions of dusts and exhaust gases from high-power motors supplying pump aggregates used for fracturing operations and from other technological devices. The total power of motors driving technological systems depends on the specific character of deposit and well and may range between a dozen to tens of thousands kW. An exemplary set of technological systems used for frac jobs is presented in figure 1. The following substances are emitted to the atmosphere during engine operation, e.g. nitrogen oxides (NOx), sulfur dioxide (SO2), carbon oxide (CO), dust PM10, ammonia, benzo(a)pyrene (B(a)P), benzene, toluene, xylene, formaldehyde, acetaldehyde, acrolein. As a consequence admissible concentrations of these substances in air can be exceeded. The influence of dust and gaseous emissions accompanying shale rock fracturing jobs is addressed in this paper. Model analyses were performed. An exemplary model of a process used for simulating propagation of atmospheric emissions in a specified calculation area (1,150 m × 1,150 m) were based on the analysis of hydraulic fracturing jobs performed in wells in Poland and abroad. For making calculations more actual, the model was located in the Gda?sk area and was ascribed its typical meteorological and orographic parameters. In the center of this area a rig site 150 m x 150 m was distinguished. The emission field was generated by 12 high-power engines supplying pump aggregates, 1680 kW each. The time of work of particular engines was established for 52 hrs (13 frac jobs, each lasting 4 hrs). It was assumed that all engines will operate simultaneously and using 100% of their power. Attention was paid to the correct modelling of the real emission field. Technical parameters of motors and the applied fuels were characterized. Emission indices were worked out by, e.g. U.S. Environmental Protection Agency or European Environment Agency. The calculations of air pollutions from analyzed motors were performed with a mathematical modelling method using Gaussian plum. The results of calculations could be used for evaluating spatial distribution of maximum 1 hour concentrations (S1), incidence of exceeding admissible 1 hour concentration values (P(D1)), percentile 99.8 or 99.726 from 1 hour concentrations and average concentrations (Sa) for selected most important for the air quality contaminants, i.e. NOx (as NO2), SO2, CO, PM10, benzo(a)pyrene, benzene, toluene, xylene, formaldehyde, acetaldehyde and acrolein. The results of calculated air concentrations of selected substances on the rig border are listed in table 9, whereas spatial distributions of NOx and PM10 concentrations in figures 3 to 8. The analysis of the obtained results did not reveal cases of exceeding Polish emission standards. However, nitrogen oxide (NOx) or dust PM10 can be expected to exceed these values, e.g. in a situation when the total power installed in motors driving technological systems in the course of hydraulic fracking will be higher than assumed in the analyses. The results of calculations show to a significant impact of nitrogen oxides (NOx) and dust PM10 emissions on air quality. The risk that emission standards are exceeded beyond the rig area is conditioned both by technological factors (total power of operating motors, parameters of combusted fuel, reduced emission technologies applied to engines, duration of frac jobs, etc.) and a number of external factors, e.g. meteorological and orographic factors or high level of emitted substances in air within the rig area. Proces hydraulicznego szczelinowania ska? ?upkowych wi??e si? z emisj? do powietrza zanieczyszcze? py?owo-gazowych z silników wysokopr??nych du?ej mocy nap?dzaj?cych agregaty pompowe do szczelinowania ska? oraz inne urz?dzenia technologiczne. ??czna moc silników nap?dzaj?cych urz?dzenia technologiczne uzale?niona jest od specyfiki z?o?a oraz specyfiki odwiertu i waha si? od kilkunastu do kilkudziesi?ciu tysi?cy kW. Przyk?adowy zestaw u

  4. Remote sensing of atmospheric water vapor using GPS data in the Hong Kong region

    NASA Astrophysics Data System (ADS)

    Liu, Yanxiong

    2000-12-01

    GPS Meteorology has been the most active research topic recently. Remote sensing of water vapor content in the atmosphere is an important objective for the ground based GPS Meteorology. This thesis focuses on the methodology for accurately remote sensing of the Precipitable Water Vapor using Hong Kong GPS data. The precipitable water vapor is converted from the wet zenith delay in GPS signal. The estimated wet zenith delay is often affected by the azimuthal asymmetry of water vapor distribution. A horizontal gradient model is therefore developed to simulate this effect. This model is proven to be beneficial to the GPS height determination and the estimation of wet zenith delay. Determination of dry zenith delay is very important for separating wet zenith delay from total tropospheric zenith delay. Three common hydrostatic zenith delay models, namely Saastamoinen, Hopfield and Black, are calibrated for the accurate determination of dry zenith delay using Hong Kong Radiosonde data. The test results indicated that the revised models could remove a 15 millimeter systematic error in local conditions. The mapping scale factor is a bridge between wet zenith delay and precipitable water vapor. The mapping scale factor varies in season and geography, and is dominated by a weighted mean tropospheric temperature. A real-time method for the calculation of the weighted mean tropospheric temperature, which is suitable for the Hong Kong region is developed by using the Sequential Regression Analysis method. Radiosonde data are treated as a standard to calculate the precipitable water vapor, dry zenith delay and weighted mean tropospheric temperature. Their accuracy caused by observed errors is analysed. The results show that the observed error cause 1.2 millimeter uncertainty for precipitable water vapor, 2 millimeter dry zenith delay error and 1 K uncertainty for weighted mean tropospheric temperature. One-month GPS data have been used to derive the precipitable water vapor in Hong Kong. The GPS-derived result is in good agreement with that from Radiosonde data. The actual difference of the precipitable water vapor is smaller than 2 millimeter in the two techniques. This result also indicates that the ground-based GPS remote sensing technique used in this thesis is applicable to GPS Meteorology in Hong Kong.

  5. Influence of small-scale North Atlantic sea surface temperature patterns on the marine boundary layer and free troposphere: a study using the atmospheric ARPEGE model

    NASA Astrophysics Data System (ADS)

    Piazza, Marie; Terray, Laurent; Boé, Julien; Maisonnave, Eric; Sanchez-Gomez, Emilia

    2015-06-01

    A high-resolution global atmospheric model is used to investigate the influence of the representation of small-scale North Atlantic sea surface temperature (SST) patterns on the atmosphere during boreal winter. Two ensembles of forced simulations are performed and compared. In the first ensemble (HRES), the full spatial resolution of the SST is maintained while small-scale features are smoothed out in the Gulf Stream region for the second ensemble (SMTH). The model shows a reasonable climatology in term of large-scale circulation and air-sea interaction coefficient when compared to reanalyses and satellite observations, respectively. The impact of small-scale SST patterns as depicted by differences between HRES and SMTH shows a strong meso-scale local mean response in terms of surface heat fluxes, convective precipitation, and to a lesser extent cloudiness. The main mechanism behind these statistical differences is that of a simple hydrostatic pressure adjustment related to increased SST and marine atmospheric boundary layer temperature gradient along the North Atlantic SST front. The model response to small-scale SST patterns also includes remote large-scale effects: upper tropospheric winds show a decrease downstream of the eddy-driven jet maxima over the central North Atlantic, while the subtropical jet exhibits a significant northward shift in particular over the eastern Mediterranean region. Significant changes are simulated in regard to the North Atlantic storm track, such as a southward shift of the storm density off the coast of North America towards the maximum SST gradient. A storm density decrease is also depicted over Greenland and the Nordic seas while a significant increase is seen over the northern part of the Mediterranean basin. Changes in Rossby wave breaking frequencies and weather regimes spatial patterns are shown to be associated to the jets and storm track changes.

  6. Non-linear Ice Sheet influence during deglaciation and its impact on the evolution of atmospheric teleconnection patterns

    NASA Astrophysics Data System (ADS)

    Dietrich, Stephan; Wassenburg, Jasper; Wei, Wei; Lohmann, Gerrit; Jens, Fohlmeister; Adrian, Immenhauser

    2013-04-01

    During present conditions atmospheric teleconnections such as the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) have a major impact on Northern Hemispheric climate. However, the Early Holocene is characterized by the presence and melting of the Laurentide Ice Sheet (LIS) leading to a different background climate in comparison to today. Here we investigate the climate evolution during the early (9 ka BP, including LIS and melt water), mid (6 ka BP) and late Holocene (pre-industrial conditions) focussing on the mechanisms and feedbacks during deglaciation by applying the state-of-the-art earth system model COSMOS. A special interest is set on the evolution of atmospheric teleconnection patterns such as the AO/NAO and the Atlantic Multidecadal Oscillation (AMO) that have a major influence on North Atlantic/European climate. The evolution and relative importance of these oscillations throughout the Holocene, however, is still largely unknown. We demonstrate that North Atlantic/European climate is affected by a shift from a more ocean-ice-dominated climate during approx. 9 ka towards a more atmosphere-dominated one during the mid to late Holocene. To isolate the contributions of the presence of the LIS and the melt water we run four different model simulations for the early Holocene sensitivity study (a standard configuration only forced with green house gases and orbital parameters, one with the additional LIS topography, one with a melt water flux of 0.09 Sv, and a fourth that combines all the external forcings). The model results show that the influence of the LIS and its melt water contribution lead to a strong non-linear cooling of surface air temperatures during deglaciation. This synergetic influence of the Laurentide Ice Sheet strengthens the effect of melting on ocean circulation during the early Holocene. The severe colder background climate during deglaciation leads to a more vulnerable ocean circulation in terms of the Atlantic Meridional Overturning Circulation. Changes of this circulation are known to affect the atmosphere as well via mechanisms like the AMO. The corresponding sea level pressure pattern is an atmospheric response to oceanic thermal forcing, which results from variations of the thermohaline circulation. The AMO has a potential to influence the shape of the subtropical high and to shift AO/NAO pressure centres towards easterly and north-easterly directions during the early Holocene. This non-stationary behaviour of the AO/NAO due to deglaciation processes is also demonstrated by a novel set of North Atlantic/European speleothem records that show an active AO/NAO all over the Holocene.

  7. Large-scale atmospheric processes in the Arctic region reproduced by Sl-AV model and reanalysis data

    NASA Astrophysics Data System (ADS)

    Kulikova, Irina; Kruglova, Ekaterina; Khan, Valentina; Kiktev, Dmitry; Tischenko, Vladimir

    2015-04-01

    The variability of large-scale atmospheric processes in the Arctic region was analyzed on the base of the NCEP/DOE reanalysis data and seasonal hindcasts from global semi-Lagrangian model (SL-AV), developed in collaboration of Hydrometeorological Centre of Russia with Institute of Numerical Mathematics. Using the factor analysis it was shown that the model reproduces well the first major variability modes to explain 85-90% of the accumulated dispersion. Teleconnection indices as the quantitative characteristics of low-frequency variability are used to identify zonal and meridional flow regimes. Composite maps indicating the spatial distribution of anomalies of the main meteorological variables (500 hPa geopotential height, the sea level atmospheric pressure, the temperature at 850 hPa, 2m air temperature, precipitation, zonal and meridional wind component) for positive and negative phases of each index of atmospheric circulation are created. Average values of composite maps are accompanied with their statistical significance assessed using the "bootstrap" technique. Main characteristics of field configuration in Arctic region of cited above meteorological parameters corresponding to positive and negative phases of circulation indices are analyzed and discussed. Ability of SL-AV model to reproduce these characteristics at monthly and seasonal time scale is discussed as well. Results of this study are aimed to improve the quality of long-range forecasts and increase the "limit of predictability" and can be useful in the practice to develop monthly and seasonal weather forecasts for the Arctic region.

  8. Influences of Northern Hemisphere Sea-Ice Change on Atmospheric Circulation

    NASA Astrophysics Data System (ADS)

    Hoshi, K.; Ukita, J.; Honda, M.; Iwamoto, K.; Nakamura, T.; Yamazaki, K.; Miyoshi, Y.; Ogawa, Y.

    2014-12-01

    Evidence from both observations and model results suggests a link between changes in the Arctic sea ice conditions and atmospheric circulation in the NH mid latitudes with its possible impacts on severe winters and extreme weather events. This study investigates underlying mechanisms for this Arctic-midlatitudes climate connection based on numerical experiments using a high-top AGCM. We compare and evaluate results from two sets of perpetual simulations (60yrs run each), one with an annual cycle of sea ice conditions from the period of 1979-1983 and the other from the 2005-2009 period while other variables and parameters including SST and GHGs are fixed.Results from the numerical experiments show that the Arctic sea ice reduction leads to cold winters in the mid-latitude land areas centered in Siberia, Europe and the North America. The winter (DJF) mean temperature at 850 hPa averaged over the mid-latitude continents decreases by about 0.4 K associated due solely to sea ice reduction.The analysis based on a wave-activity flux indicates that this cooling is due to low-level cold advection. In early winter negative geopotential height anomalies over Siberia and the North America develop as a stationary Rossby wave response to anomalous turbulent surface heat fluxes associated with the sea-ice reduction in the Barents and Kala Seas. As winter progresses further wave propagation acts to intensify positive geopotential height anomalies over the high Arctic, which eventually leads to cold advections in the lower troposphere. In addition, we identify a pathway via the stratosphere which appears to aid this intensification of positive geopotential height anomalies.Observations in general support a similar relationship. For example, on interannual timescale there is a significant positive relationship between the September NH SIE time series and surface temperatures in continental regions.Our results have significant implications that sea ice can be used as a basis for mid-range prediction and that underlying mechanisms can be in part understood within the framework of the Rossby wave propagation and wave-mean interaction theory.

  9. Possible ENSO influence on soil N2O emissions and atmospheric N2O mole fractions

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Schlosser, C. A.; Prinn, R. G.

    2012-12-01

    N2O is currently one of the most important ozone-depleting substances, and the third largest anthropogenic-biogenic greenhouse gas. Despite its impact on stratospheric ozone destruction, it is not regulated by the Montreal Protocol, and global observations show that the N2O mole fractions is increasing continuously at a rate of 0.2 to 0.3% per year. Sinks and sources of N2O still have large uncertainties but previous studies have estimated that soil emissions account for approximately 60% of the total emissions. Because the variability in soil emissions could potentially have important implications for regional and global climate change, and vice versa, it is essential to better understand the processes and feedbacks associated with soil N2O emissions. To achieve this goal and better quantify global soil N2O emissions, we have included the denitrification-decomposition module (DNDC) into the Community Land Model with coupled Carbon and Nitrogen cycles (CLM-CN) version 3.5. Using four different bias-corrected, reanalysis-based meteorological datasets, we have constructed four global gridded soil N2O emission estimates for the years 1975 through the mid-2000s. We find evidence for a significant El Niño-Southern Oscillation influence on soil N2O emissions with reduced emissions in El Niño years and increased emissions in La Niña years in our model. In addition, we use these soil emission (and other source) estimates in a 3-dimensional chemical transport model - the Model for OZone And Related chemical Tracers (MOZART) version 4 - to analyze the impact of this inter-annual variability in soil emissions on simulations of N2O measurements at AGAGE and NOAA-ESRL observational sites.

  10. Influence of non-stationary field of magnetospheric convection on the D-region

    NASA Technical Reports Server (NTRS)

    Eliseyev, A. YU.; Kashpar, Yu. V.; Nikitin, A. A.

    1989-01-01

    Perturbations of F region electron density caused by the extension of magnetospheric convection electric field to middle latitudes are already well known. For the D region of the first observations are believed to be reported by Eliseyev, Kashpar and Nikitin (1988). On several occasions, following the southward turning of the Bz-component of interplanetary magnetic field (IMF) small disturbances of the D region electron density were detected at night by steep-incidence VLF sounding, which may be attributed to the influence of the penetrated convection electric field (CEF). Some evidence is given of a local time dependence of the CEF effect in the D region and a rather good correlation is demonstrated at the initial stage of disturbance between high latitude magnetic field variations and simultaneous perturbation of the midlatitude ionospheric reflection height.

  11. The influence of atmospheric conditions on the leakage current of ceramic insulators on the Colombian Caribbean coast.

    PubMed

    Castillo Sierra, Rafael; Oviedo-Trespalacios, Oscar; Candelo, John E; Soto, Jose D

    2015-02-01

    The contamination of electrical insulators is one of the major contributors to the risk of operation outages in electrical substations, especially in coastal zones with high salinity levels and atmospheric pollution. By using the measurement of leakage-currents, which is one of the main indicators of contamination in insulators, this work seeks to the determine the correlation with climatic variables, such as ambient temperature, relative humidity, solar irradiance, atmospheric pressure and wind speed and direction. The results obtained provide an input to the behaviour of the leakage current under atmospheric conditions that are particular to the Caribbean coast of Colombia. Spearman's rank correlation coefficients and principal component analysis are utilised to determine the significant relationships among the different variables under consideration. The necessary information for the study was obtained via historical databases of both atmospheric variables and the leakage current measured in over a period of 1 year in a 220-kV potential transformer insulator. We identified the influencing factors of temperature, humidity, radiation, wind speed and direction on the magnitude of the leakage current as the most relevant. PMID:25339532

  12. Influences of Forest Tree Species and Early Spring Temperature on Surface-Atmosphere Transfers of Water and Carbon in the Northeastern U.S.

    NASA Astrophysics Data System (ADS)

    Hadley, J. L.; Kuzeja, P.; Mulcahy, T.; Singh, S.

    2008-12-01

    Influences of Forest Tree Species and Early Spring Temperature on Surface-Atmosphere Transfers of Water and Carbon in the Northeastern U.S. Julian Hadley, Paul Kuzeja, Safina Singh and Thomas Mulcahy Transfers of water vapor from terrestrial ecosystems to the atmosphere affect regional hydrology, weather and climate over short time scales, and forest-atmosphere CO2 exchange affects global climate over long timescales. To better understand these effects for forests dominated by two very different tree species, we measured forest-atmosphere water vapor and CO2 transfers by the eddy flux technique to at two sites in central Massachusetts USA for three years. Average annual evapotranspiration (ET) for a young deciduous forest dominated by red oak (Quercus rubra L., the most abundant tree species in the area), was about 430 mm or 25 percent greater than for a coniferous forest dominated by 100 to 230 year old eastern hemlock (Tsuga canadensis L.). The difference in ET was most pronounced in July and August when the deciduous forest lost about 50 percent more water by ET in the average year (192 mm for oak forest versus 130 mm for hemlock). These data indicate that if deciduous trees with similar physiology to red oak replace hemlocks, summertime ET will increase while summer streamflow, soil water content and the extent of year- round wetlands will decrease. Increased summertime ET should also lead to slightly higher regional atmospheric humidity and precipitation. Hemlock-to-deciduous forest conversion has occurred from North Carolina to southern New England and is continuing northward as a lethal insect pest, the hemlock woolly adelgid (Adelges tsugae Annand) continues to kill hemlocks. Average annual carbon storage for the old hemlock forest in our study was about 3.3 Mg C/ha, nearly equal to the average for the deciduous forest, 3.5 Mg C/ha. This calls into question ecological theory that predicts large declines in the rate of carbon uptake for old forests, and indicates that annual carbon storage will not necessarily increase over the long term after hemlock trees are killed by the hemlock woolly adelgid and replaced by deciduous species. Maximum monthly carbon storage in the hemlock forest occurred in spring (April and May) and was enhanced by early soil thawing and cessation of nighttime frost. This pattern is probably common to many evergreen conifers in the northeastern U.S., so climate warming that includes an earlier end to freezing temperatures in spring should increase C storage by conifer forests in the northeastern U.S. - unless this effect is canceled out by reduced C uptake or enhanced C loss due to changes in summer and fall climate.

  13. Studies of regional-scale climate variability and change: Hidden Markov models and coupled ocean-atmosphere modes

    SciTech Connect

    M. Ghil , PI; S. Kravtsov; A. W. Robertson; P. Smyth

    2008-10-14

    In this project we developed further a twin approach to the study of regional-scale climate variability and change. The two approaches involved probabilistic network (PN) models (sometimes called dynamic Bayesian networks) and intermediate-complexity coupled ocean-atmosphere models (ICMs). We thus made progress in identifying the predictable modes of climate variability and investigating their impacts on the regional scale. In previous work sponsored by DOE�s Climate Change Prediction Program (CCPP), we had developed a family of PNs (similar to Hidden Markov Models) to simulate historical records of daily rainfall, and used them to downscale seasonal predictions of general circulation models (GCMs). Using an idealized atmospheric model, we had established a novel mechanism through which ocean-induced sea-surface temperature (SST) anomalies might in�uence large-scale atmospheric circulation patterns on interannual and longer time scales; similar patterns were found in a hybrid coupled ocean�atmosphere�sea-ice model. In this continuation project, we built on these ICM results and PN model development to address prediction of rainfall and temperature statistics at the local scale, associated with global climate variability and change, and to investigate the impact of the latter on coupled ocean�atmosphere modes. Our main project results consist of extensive further development of the hidden Markov models for rainfall simulation and downscaling together with the development of associated software; new intermediate coupled models; a new methodology of inverse modeling for linking ICMs with observations and GCM simulations, called empirical mode reduction (EMR); and observational studies of decadal and multi-decadal natural climate variability, informed by ICM simulations. A particularly timely by-product of this work is an extensive study of clustering of cyclone tracks in the extratropical Atlantic and the western Tropical Pacific, with potential applications to predicting landfall.

  14. Development and application of a regional-scale atmospheric mercury model based on WRF/Chem: a Mediterranean area investigation.

    PubMed

    Gencarelli, Christian Natale; De Simone, Francesco; Hedgecock, Ian Michael; Sprovieri, Francesca; Pirrone, Nicola

    2014-03-01

    The emission, transport, deposition and eventual fate of mercury (Hg) in the Mediterranean area has been studied using a modified version of the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem). This model version has been developed specifically with the aim to simulate the atmospheric processes determining atmospheric Hg emissions, concentrations and deposition online at high spatial resolution. For this purpose, the gas phase chemistry of Hg and a parametrised representation of atmospheric Hg aqueous chemistry have been added to the regional acid deposition model version 2 chemical mechanism in WRF/Chem. Anthropogenic mercury emissions from the Arctic Monitoring and Assessment Programme included in the emissions preprocessor, mercury evasion from the sea surface and Hg released from biomass burning have also been included. Dry and wet deposition processes for Hg have been implemented. The model has been tested for the whole of 2009 using measurements of total gaseous mercury from the European Monitoring and Evaluation Programme monitoring network. Speciated measurement data of atmospheric elemental Hg, gaseous oxidised Hg and Hg associated with particulate matter, from a Mediterranean oceanographic campaign (June 2009), has permitted the model's ability to simulate the atmospheric redox chemistry of Hg to be assessed. The model results highlight the importance of both the boundary conditions employed and the accuracy of the mercury speciation in the emission database. The model has permitted the reevaluation of the deposition to, and the emission from, the Mediterranean Sea. In light of the well-known high concentrations of methylmercury in a number of Mediterranean fish species, this information is important in establishing the mass balance of Hg for the Mediterranean Sea. The model results support the idea that the Mediterranean Sea is a net source of Hg to the atmosphere and suggest that the net flux is ?30 Mg year(-1) of elemental Hg. PMID:24170496

  15. Influence of the Southeast Asian biomass burnings on the atmospheric persistent organic pollutants observed at near sources and receptor site

    NASA Astrophysics Data System (ADS)

    Chang, Shun-Shiang; Lee, Wen-Jhy; Wang, Lin-Chi; Lin, Neng-Huei; Chang-Chien, Guo-Ping

    2013-10-01

    Persistent organic pollutants (POPs) such as PCDD/Fs, PCBs, PBDD/Fs, PBBs and PBDEs are bio-accumulative, toxic, and susceptible to long-range transport (LRT). This study is the first that comprehensively discusses the long-range atmospheric transport behavior of these five groups of POPs. The main goal is to investigate the atmospheric characteristics of these POPs at the biomass burning sites of Chiang Mai in Thailand, and Da Nang in Vietnam, as well as the influence of the Southeast Asian biomass burnings on the Lulin Atmospheric Background Station (LABS) in Taiwan. Biomass burning in Southeast Asia is usually carried to remove the residues of agricultural activities. The ambient air in Da Nang seems to be more seriously affected by the local biomass burnings than that in Chiang Mai. The elevated atmospheric brominated POP (PBDD/Fs, PBBs and PBDEs) concentrations in Da Nang were attributed to the biomass burning and viewed as mostly unrelated to the local use of brominated flame retardants. In the spring of 2010, the mean atmospheric concentrations in LABS during the first and second Intensive Observation Periods (IOPs) were 0.00428 and 0.00232 pg I-TEQ Nm-3 for PCDD/Fs, 0.000311 and 0.000282 pg WHO-TEQ m-3 for PCBs, 0.000379 and 0.000449 pg TEQ Nm-3 for total PBDD/Fs, 0.0208 and 0.0163 pg Nm-3 for total PBBs, and 109 and 18.2 pg Nm-3 for total PBDEs, respectively. These values represent the above concentrations due to the Southeast Asian biomass burnings. The affected atmospheric POP concentrations at the LABS were still at least one order lower than those in other atmospheric environments, except for the PBDE concentrations during the first IOP (109 pg Nm-3), which was surprisingly higher than those in Taiwanese metal complex areas (93.9 pg Nm-3) and urban areas (34.7 pg Nm-3). Atmospheric POP concentrations do not seem to dramatically decrease during long-range transport, and the reasons for this need to be further investigated.

  16. Environmental effect and genetic influence: a regional cancer predisposition survey in the Zonguldak region of Northwest Turkey

    NASA Astrophysics Data System (ADS)

    Kadir, Selahattin; Önen-Hall, A. Piril; Aydin, S. Nihal; Yakicier, Cengiz; Akarsu, Nurten; Tuncer, Murat

    2008-03-01

    The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak region of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe-Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the region strongly suggested an environmental effect and a genetic influence on the increased cancer incidence in the region. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the region.

  17. Aerosol influence on energy balance of the middle atmosphere of Jupiter.

    PubMed

    Zhang, Xi; West, Robert A; Irwin, Patrick G J; Nixon, Conor A; Yung, Yuk L

    2015-01-01

    Aerosols are ubiquitous in planetary atmospheres in the Solar System. However, radiative forcing on Jupiter has traditionally been attributed to solar heating and infrared cooling of gaseous constituents only, while the significance of aerosol radiative effects has been a long-standing controversy. Here we show, based on observations from the NASA spacecraft Voyager and Cassini, that gases alone cannot maintain the global energy balance in the middle atmosphere of Jupiter. Instead, a thick aerosol layer consisting of fluffy, fractal aggregate particles produced by photochemistry and auroral chemistry dominates the stratospheric radiative heating at middle and high latitudes, exceeding the local gas heating rate by a factor of 5-10. On a global average, aerosol heating is comparable to the gas contribution and aerosol cooling is more important than previously thought. We argue that fractal aggregate particles may also have a significant role in controlling the atmospheric radiative energy balance on other planets, as on Jupiter. PMID:26694318

  18. Influences of atmospheric conditions and air mass on the ratio of ultraviolet to total solar radiation

    SciTech Connect

    Riordan, C.J.; Hulstrom, R.L.; Myers, D.R.

    1990-08-01

    The technology to detoxify hazardous wastes using ultraviolet (UV) solar radiation is being investigated by the DOE/SERI Solar Thermal Technology Program. One of the elements of the technology evaluation is the assessment and characterization of UV solar radiation resources available for detoxification processes. This report describes the major atmospheric variables that determine the amount of UV solar radiation at the earth's surface, and how the ratio of UV-to-total solar radiation varies with atmospheric conditions. These ratios are calculated from broadband and spectral solar radiation measurements acquired at SERI, and obtained from the literature on modeled and measured UV solar radiation. The following sections discuss the atmospheric effects on UV solar radiation and provide UV-to-total solar radiation ratios from published studies, as well as measured values from SERI's data. A summary and conclusions are also given.

  19. Influence of geomagnetic disturbances on seasonal dynamics of daily variations in atmospherics

    NASA Astrophysics Data System (ADS)

    Kirillov, V. I.; Beloglazov, M. I.; Pchelkin, V. V.; Galakhov, A. A.

    2015-03-01

    Daily variations were studied in atmospherics at frequencies of 600 Hz and 6 kHz, which were recorded on the Kola Peninsula from 2012 to 2013 in different geomagnetic conditions. It is shown that increased geomagnetic storminess does not significantly change daily variations in the hourly mean flow and amplitudes of atmospherics at either frequency for the west-east component. For the north-south component, this is true only for hourly mean amplitudes. The distribution of amplitudes of atmospherics recorded is satisfactorily described by the well-known formula P( X) = [1 + ( X/ X 50) k ]-1, where 1.9 < k < 2.9 for a frequency of 600 Hz and 1 < k < 2 for 6000 Hz.

  20. Incorporating water table dynamics in climate modeling: 3. Simulated groundwater influence on coupled land-atmosphere

    E-print Network

    Robock, Alan

    Incorporating water table dynamics in climate modeling: 3. Simulated groundwater influence), Incorporating water table dynamics in climate modeling: 3. Simulated groundwater influence on coupled land, causing the water table to rise near the land surface despite the dry climate. We suggested

  1. Influence of sub-grid scale parameterizations on atmospheric variability over a heterogeneous agricultural area

    NASA Astrophysics Data System (ADS)

    Timmermans, Wim; Andreu, Ana; Porté-Agel, Fernando; Albertson, John

    2015-04-01

    Virtually all remote sensing based Soil-Vegetation-Atmosphere Transfer (SVAT) Schemes assume homogeneous, or decoupled atmospheric variables over their modeling domain. This assumption can lead to erroneous flux estimation since landscapes are inherently heterogeneous with variability in land surface state variables inducing spatial variability in the near surface air properties, which in turn affect the fluxes. A Large Eddy Simulation (LES) model is coupled to a remote sensing based SVAT that accounts for soil and vegetation (dual source) contributions to mass and energy exchanges in order to study the feedback effects between spatially variable land cover and spatial variability in fluxes, through the induction of spatial variability in the lower atmosphere. Previous studies demonstrated that an increase in the correlation between surface and lower boundary layer states with increasing surface state contrast modulated relative increases in the spatial variance in the sensible heat flux. A multi-scale analysis of the land - atmosphere feedback, using a simple wavelet decomposition technique, showed the most significant correlation at scales from 500 to 1000 m. These feedback effects act to limit the spatial variability in the flux, implying that ignoring atmospheric feedback from land surface turbulent exchange rates will cause the largest errors at the extremes. To improve the modelling of spatially distributed fluxes a better understanding of how the surface heterogeneities are transported into the lower atmospheric boundary layer is needed. Near the surface the momentum and scalar (temperature and moisture) transport is dominated by the smallest size eddies. Therefore, typically the performance of Large Eddy Simulation models near the surface depends largely on the performance of the so-called Sub-Grid-Scale (SGS) parameterizations of momentum and scalar fluxes. The effect of recently developed scale-invariant and scale-dependent dynamic SGS models for viscosity and diffusivity is discussed using airborne and ground-based observations from a campaign (REFLEX-2012) over a heterogeneous agricultural area in the southern part of Spain.

  2. Quantifying atmospheric methane emissions from the Haynesville, Fayetteville, and northeastern Marcellus shale gas production regions

    NASA Astrophysics Data System (ADS)

    Peischl, J.; Ryerson, T. B.; Aikin, K. C.; Gouw, J. A.; Gilman, J. B.; Holloway, J. S.; Lerner, B. M.; Nadkarni, R.; Neuman, J. A.; Nowak, J. B.; Trainer, M.; Warneke, C.; Parrish, D. D.

    2015-03-01

    We present measurements of methane (CH4) taken aboard a NOAA WP-3D research aircraft in 2013 over the Haynesville shale region in eastern Texas/northwestern Louisiana, the Fayetteville shale region in Arkansas, and the northeastern Pennsylvania portion of the Marcellus shale region, which accounted for the majority of Marcellus shale gas production that year. We calculate emission rates from the horizontal CH4 flux in the planetary boundary layer downwind of each region after subtracting the CH4 flux entering the region upwind. We find 1 day CH4 emissions of (8.0 ± 2.7) × 107 g/h from the Haynesville region, (3.9 ± 1.8) × 107 g/h from the Fayetteville region, and (1.5 ± 0.6) × 107 g/h from the Marcellus region in northeastern Pennsylvania. Finally, we compare the CH4 emissions to the total volume of natural gas extracted from each region to derive a loss rate from production operations of 1.0-2.1% from the Haynesville region, 1.0-2.8% from the Fayetteville region, and 0.18-0.41% from the Marcellus region in northeastern Pennsylvania. The climate impact of CH4 loss from shale gas production depends upon the total leakage from all production regions. The regions investigated in this work represented over half of the U.S. shale gas production in 2013, and we find generally lower loss rates than those reported in earlier studies of regions that made smaller contributions to total production. Hence, the national average CH4 loss rate from shale gas production may be lower than values extrapolated from the earlier studies.

  3. The atmospheric influence on the results from the Swedish GPS network

    NASA Astrophysics Data System (ADS)

    Johasson, J. M.; Emardson, T. R.; Jarlemark, P. O. J.; Gradinarsky, L. P.; Elgered, G.

    The SWEPOS network currently consists of 21 continuously operating GPS stations. The GPS receiver at the Onsala site is collocated with a microwave radiometer measuring the integrated amount of water vapour along the line of sight. We have studied the correlation between GPS estimates of position and variations in the atmosphere using data from the autumns of 1995 and 1996, and found only small correlations between the estimated positions and the atmospheric quantities studied. We are, however, aware of other systematic errors, e.g. caused by radomes above the GPS antennas which may presently dominate the error budget

  4. Innovative optical spectrometers for ice core sciences and atmospheric monitoring at polar regions

    NASA Astrophysics Data System (ADS)

    Grilli, Roberto; Alemany, Olivier; Chappellaz, Jérôme; Desbois, Thibault; Faïn, Xavier; Kassi, Samir; Kerstel, Erik; Legrand, Michel; Marrocco, Nicola; Méjean, Guillaume; Preunkert, Suzanne; Romanini, Daniele; Triest, Jack; Ventrillard, Irene

    2015-04-01

    In this talk recent developments accomplished from a collaboration between the Laboratoire Interdisciplinaire de Physique (LIPhy) and the Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) both in Grenoble (France), are discussed, covering atmospheric chemistry of high reactive species in polar regions and employing optical spectrometers for both in situ and laboratory measurements of glacial archives. In the framework of an ANR project, a transportable spectrometer based on the injection of a broadband frequency comb laser into a high-finesse optical cavity for the detection of IO, BrO, NO2 and H2CO has been realized.[1] The robust spectrometer provides shot-noise limited measurements for as long as 10 minutes, reaching detection limits of 0.04, 2, 10 and 200 ppt (2?) for the four species, respectively. During the austral summer of 2011/12 the instrument has been used for monitoring, for the first time, NO2, IO and BrO at Dumont d'Urville Station at East of Antarctica. The measurements highlighted a different chemistry between East and West coast, with the halogen chemistry being promoted to the West and the OH and NOx chemistry on the East.[2] In the framework of a SUBGLACIOR project, an innovative drilling probe has been realized. The instrument is capable of retrieving in situ real-time vertical profiles of CH4 and ?D of H2O trapped inside the ice sheet down to more than 3 km of depth within a single Antarctic season. The drilling probe containing an embedded OFCEAS (optical-feedback cavity-enhanced absorption spectroscopy) spectrometer will be extremely useful for (i) identify potential sites for investigating the oldest ice (aiming 1.5 Myrs BP records for resolving a major climate reorganization called the Mid-Pleistocene transition occurred around 1 Myrs ago) and (ii) providing direct access to past temperatures and climate cycles thanks to the vertical distribution of two key climatic signatures.[3] The spectrometer provides detection limit of 0.2 ppbv for CH4 and a precision of 0.2o on the ?D of H2O within ~1 min of integration time. The spectrometer and the home-made gas sampling has been tested during an oceanographic campaign last summer in the Mediterranean Sea, measuring the vertical distribution of CH4 dissolved in seawater. The project is now moving forward its final goal which consists of employing the probe for a first test season at Concordia station during the Austral summer of 2016/17, and then for the 'oldest ice challenge' drilling season scheduled in the Austral summer of 2017/18. Finally, preliminary results on the isotope ratio measurements of CO18O,13CO2 and 13CO18O will be presented. A novel spectrometer, based on OFCAES technique employing a Quantum Cascade Laser around 4.4 ?m wavelength, offers a precision below 0.05 o for the three isotopic anomalies, for 200 ppmv of CO2 samples. The optical device will be employed for laboratory experiments coupling it with a continuous ice-crushing extraction system for analyzing trapped bubbles of gas in Antarctica ice cores. [1] R. Grilli, G. Méjean, S. Kassi, I. Ventrillard, C. Abd-Alrahman, and D. Romanini, 'Frequency Comb Based Spectrometer for in Situ and Real Time Measurements of IO, BrO, NO2, and H2CO at pptv and ppqv Levels.,' Environ. Sci. Technol., vol. 46, no. 19, pp. 10704-10, Oct. 2012. [2] R. Grilli, M. Legrand, A. Kukui, G. Méjean, S. Preunkert, and D. Romanini, 'First investigations of IO, BrO, and NO2 summer atmospheric levels at a coastal East Antarctic site using mode-locked cavity enhanced absorption spectroscopy,' Geophys. Res. Lett., vol. 40, pp. 1-6, Feb. 2013. [3] R. Grilli, N. Marrocco, T. Desbois, C. Guillerm, J. Triest, E. Kerstel, and D. Romanini, 'Invited Article: SUBGLACIOR: An optical analyzer embedded in an Antarctic ice probe for exploring the past climate,' Rev. Sci. Instrum., vol. 85, no. 111301, pp. 1-7, 2014.

  5. Polybrominated diphenyl ethers in various atmospheric environments of Taiwan: their levels, source identification and influence of combustion sources.

    PubMed

    Wang, Lin-Chi; Lee, Wen-Jhy; Lee, Wei-Shan; Chang-Chien, Guo-Ping

    2011-08-01

    In this study, ambient air samples from different atmospheric environments were examined for both PBDE and PCDD/F characteristics to verify that combustion is a significant PBDE emission source. The mean ± SD atmospheric PBDE concentrations were 165 ± 65.0 pg Nm(-3) in the heavy steel complex area and 93.9 ± 24.5 pg Nm(-3) in the metals complex areas, 4.7 and 2.7 times higher than that (35.3 ± 15.5 pg Nm(-3)) in the urban areas, respectively. The statistically high correlation (r=0.871, p<0.001) found between the atmospheric PBDE and PCDD/F concentrations reveals that the combustion sources are the most likely PBDE emission sources. Correspondence analysis shows the atmospheric PBDEs of the heavy steel and metals complex areas are associated with BDE-209, -203, -207, -208, indicative of combustion source contributions. Furthermore, the PBDEs in urban ambient air experience the influence of the evaporative releases of the commercial penta- and octa-BDE mixtures, as well as combustion source emissions. By comparing the PBDE homologues of indoor air, urban ambient air, and stack flue gases of combustion sources, we found that the lighter brominated PBDEs in urban ambient air were contributed by the indoor air, while their highly brominated ones were from the combustion sources, such as vehicles. The developed source identification measure can be used to clarify possible PBDE sources not only for Taiwanese atmosphere but also for other environmental media in other countries associated with various emission sources in the future. PMID:21723587

  6. Land-Atmosphere interaction over North America in the current and future climates using Canadian Regional Climate Model (CRCM5)

    NASA Astrophysics Data System (ADS)

    Diro, G. T.; Sushama, L.

    2014-12-01

    In this study, we investigate how land-atmosphere coupling and interaction may affect future extreme temperature events, particularly the role of soil moisture in modulating the frequency and duration of extreme hot events using the fifth generation of Canadian Regional Climate Model (CRCM5). With this objective, two sets of simulations were carried out: the soil moisture is coupled with the atmosphere for both current and future periods in the first set of simulations, while climatological values of soil moisture (obtained from the first set) are prescribed for current (1981-2010) and future (2071-2100) periods for the second set of simulations. Each set consists of 4 simulations, driven by two different GCMs (MPI and CanESM2) for two representative concentration pathways (RCP4.5 and RCP8.5). Associated with the decrease of soil moisture in the future climate, the projected soil moisture-temperature coupling regions extend beyond the Great Plains in to the Canadian Prairies. Results also indicate that the land surface plays a significant role in the projected change of extreme temperature events (e.g. number of hot days) over parts of North America. It is noted that the impact of land-atmosphere coupling is stronger on the changes in the variability than on the mean and these changes are co-located with areas where the reduction of soil moisture is intense.

  7. Observations and simulations of synoptic, regional, and local variations in atmospheric CO2

    E-print Network

    Collett Jr., Jeffrey L.

    of land surface physics and carbon exchange (SiB 2.5) and the atmosphere (RAMS 5.04), in which CO2 respiration in the southeast United States. The low-[CO2] air to the southwest of Wisconsin and the high-[CO2:10.1029/2006JD007410. 1. Introduction [2] Fossil fuel burning, deforestation, cement manufac- ture

  8. Satellite estimates of shortwave surface radiation and atmospheric meteorology for the BOREAS experiment region

    NASA Technical Reports Server (NTRS)

    Moats, C. D.; Whitlock, C. H.; Lecroy, S. R.; Dipasquale, R. C.

    1994-01-01

    This report provides background data for the Boreal Ecosystem Atmosphere Study (BOREAS) sites, including daily, seasonal, interannual, and spatial variability of shortwave (SW) radiation at the Earth's surface. This background data, from the Version 1.1 SW data set, was provided by the Surface Radiation Budget (SRB) Climatology Project established by the World Climate Research Program (WCRP).

  9. Interdisciplinary study of atmospheric processes and constituents of the mid-Atlantic coastal region

    NASA Technical Reports Server (NTRS)

    Kindle, E. C.

    1976-01-01

    Progress is reported in the following areas: analysis of the air quality of Plymouth Park, Chesapeake, Virginia; background analysis and impact assessment for the proposed expansion of Busch Gardens; application of remote sensing and atmospheric interaction; and biosphere interaction. Plans for further study are included.

  10. Modeling the Dynamics of the Middle Atmosphere and Lower Thermosphere Under the Influence of Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Our Numerical Spectral Model (NSM), which extends from the ground up into the thermosphere, is non-linear, time-dependent and has been employed for 2D and 3D applications. The standard version of the NSM incorporates Hines' Doppler Spread Parameterization for small scale gravity waves (GW), but planetary waves generated in the troposphere have also been incorporated. The NSM has been applied to describe: (1) the anomalous seasonal variations of the zonal circulation and temperature in the upper mesosphere, (2) the equatorial oscillations (quasi-biennial and semi-annual oscillations (QBO and SAO)) extending from the stratosphere into the upper mesosphere, (3) the diurnal and semi-diurnal tides, and (4) the planetary waves that are excited in the mesosphere. With the emphasis to provide understanding, we present here results from numerical experiments with the NSM that shed light on the GW processes that are of central importance in the mesosphere and lower thermosphere. These are our conclusions: (1) The large semiannual variations in the diurnal tide (DT), with peak amplitudes observed around equinox, are produced primarily by GW interactions that involve, in part, planetary waves. The DT, like planetary waves, tends to be amplified by GW momentum deposition, which reduces also the vertical wavelength, but variations in eddy viscosity associated with GW interactions are also important. (2) The semidiurnal tide (SDT) and its phase in particular, is strongly influenced by the mean zonal circulation. The SDT, individually, is also amplified by GW. But the DT filters out GW such that the GW interaction effectively reduces the amplitude of the SDT, producing a strong nonlinear interaction between the DT and SDT. (3) Without external time dependent energy or momentum sources, planetary waves (PW) are generated in the model for zonal wavenumbers 1 to 4, which have amplitudes in the mesosphere above 50 km as large as 40 m/s and periods between 50 and 2 days. The waves are generated primarily during solstice conditions, which indicates that the baroclinic instability (associated with the GW induced reversal in the latitudinal temperature gradient) is playing an important role. Numerical experiment show that GW, directly, also greatly amplify the PW. A common feature of the PW generated in summer and winter is that their vertical wavelengths throughout the mesosphere are large, which indicates that the waves are not propagating freely but are generated throughout the region. Another common feature is that the PW propagate preferentially westward in summer and eastward in winter, being launched from the westward and eastward zonal winds that prevail respectively in summer and winter at altitudes below 80 km. (4) Planetary waves generated internally by baroclinic instability and GW interaction produce large amplitude modulations of the DT and SDT. In summary we conclude that GW play major roles in generating and amplifying the dynamical components in the MLT region and, acting principally through wave filtering, produce important non-linear interactions between the components.

  11. Toward robust and consistent regional CO2 flux estimates from in situ and spaceborne measurements of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Chevallier, Frédéric; Palmer, Paul I.; Feng, Liang; Boesch, Hartmut; O'Dell, Christopher W.; Bousquet, Philippe

    2014-02-01

    We evaluate the robustness and consistency of global and regional posterior CO2 flux estimates for 2010 inferred from two versions of bias-corrected CO2 column retrievals from the Japanese Greenhouse Gases Observing Satellite (GOSAT). Six satellite-based inversions, generated from three atmospheric transport models and two independent Bayesian inference algorithms, facilitate a rigorous investigation of the uncertainty of the inverted fluxes. This ensemble shows hemispheric and regional differences in posterior flux estimates that are beyond 1 sigma uncertainties and in some regions are unrealistic. We recognize the importance of these satellite data in further understanding the contemporary carbon cycle but we argue that more resources should be invested in characterizing the errors of the prior fluxes, the systematic errors of the retrievals, and the systematic errors of the transport models, to improve confidence in the resulting posterior fluxes.

  12. The Structure of the Upper Atmosphere of Venus - New Measurements and Models of the Northern Polar Region

    NASA Astrophysics Data System (ADS)

    Svedhem, H.; Mueller-Wodarg, I. C.; Rosenblatt, P.

    2011-12-01

    Until recently the only information on the structure of the polar upper atmosphere of Venus available has been based on the reference atmosphere models such as the VTS3 or VIRA models. These models extrapolate the values from low latitudes to high latitudes by using equivalent solar zenith angles. New measurements by Venus Express show that such extrapolations not always give correct results and that there is a general overestimate of the density at high latitudes. These new results have been reached by using two different but related techniques, both using an atmospheric drag effect on the spacecraft. By reducing the pericentre altitude the total mass density in the altitude range 150-200km can be measured in situ by monitoring the orbital decay caused by the drag on the spacecraft by the atmosphere via direct tracking of the Doppler signal on the telecommunication link. Such measurements have been performed with Venus Express several times during the last years as part of the Venus Express Atmospheric Drag Experiment (VExADE). The results indicate a large variability within only a few days and have led to questions if these variations are real or within the uncertainty of the measurements. A completely different and independent measurement is given by monitoring the torque asserted by the atmosphere on the spacecraft. This is done by monitoring the momentum accumulated in the reaction wheels during the pericentre pass and at the same time considering all other perturbing forces. This requires the spacecraft to fly in an asymmetric attitude with respect to the centre of gravity, centre of drag and the velocity vector. This technique has proven very sensitive, in particular if the geometric asymmetry is large, and offers an additional method of measuring atmospheric densities in-situ that previously had not been explored with the Venus Express spacecraft. Similar measurements have been done in the past by Magellan at Venus and by Cassini at Titan. Between 2009 and 2011 several campaigns, with altitudes going as low as 165 km, were held. The highest density measured was 7.7 10-12kg/m3 which is significantly less than earlier models predict. The results largely confirm the density measurements by the VExADE drag measurements and add to the confidence in the results from these measurements. By using these drag and torque results and assuming a hydrostatic diffusive equilibrium atmosphere a new model has been constructed. The model is fitted to the Venus Express remote sensing measurements in the upper mesosphere (VeRa radio occultation data) and lower thermosphere (SpicaV/SOIR data) to give a continuous transition across the different regions.

  13. A direct human influence on atmospheric CO2 seasonality from increased cropland productivity

    NASA Astrophysics Data System (ADS)

    Gray, J. M.; Frolking, S. E.; Kort, E. A.; Ray, D. K.; Kucharik, C. J.; Ramankutty, N.; Friedl, M. A.

    2014-12-01

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50% over the last 50 years. This increase has been linked to changes in Temperate, Boreal and Arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind observed changes in atmospheric CO2 seasonality remain unclear. Here we show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as 25% of observed changes in atmospheric CO2 seasonality, and perhaps more. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240% between 1961-2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 Pg. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the Midwestern United States and Northern China. Since a substantial portion of seasonality enhancement results from a process that is roughly neutral in terms of its impact on the terrestrial carbon sink, our results show that care must be taken when making inferences regarding the linkages between CO2 seasonality and terrestrial carbon sink dynamics. More generally, these results demonstrate how intensive management of agricultural ecosystems over the last five decades have imparted a substantial and direct fingerprint of anthropogenic activities on seasonal patterns of Northern Hemisphere atmospheric CO2.

  14. ATMOSPHERIC MERCURY IN THE LAKE MICHIGAN BASIN: INFLUENCE OF THE CHICAGO/GARY URBAN AREA

    EPA Science Inventory

    The relative importance of the Chicago/Gay urban area was investigated to determine its impact on atmospheric mercury (Hg) concentrations and wet deposition in the Lake Michigan basin. Event wet-only precipitation, total particulate, and vapor phase samples were collected for ...

  15. The influence of forests on atmospheric heating during the snowmelt season

    SciTech Connect

    Yamazaki, T.

    1995-02-01

    Atmospheric heating during the snowmelt season has been studied by means of data analysis and numerical model experiments. As a result of the data analysis, it was shown that in some examples the daytime air temperature rose above 0 C, even if the ground surface was covered by snow. Moreover, it was found that the number of days when the daytime air temperature rose above 0 C was large when the duration of sunshine increased. However, the increase was not related to the wind speed. Therefore, the air temperature over snow cover increases during the daytime if the sunshine is strong even under calm conditions (weak advection). On the other hand, the following result was obtained with the use of a local circulation model combined with a canopy heat balance model. The atmosphere was heated over the plains if forested areas existed around the plains, even if the plains surfaces were covered by snow without forests. An upward sensible heat flux was supplied from the forest canopy, resulting in atmospheric heating. It was concluded that the existence of forests was one of the main causes of atmospheric heating during the snowmelt season.

  16. Influence of atmospheric and climatic change on plant-pathogen interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Atmospheric change studies conducted in Free Air Concentration Enrichment (FACE) systems and open topped chambers have increased our understanding of how factors, such as rising CO2 and O3 levels, impact the development of plant disease epidemics. Using these systems, plant scientists have been able...

  17. Downwash of atmospherically deposited trace metals in peat and the influence of rainfall intensity: an experimental test.

    PubMed

    Hansson, Sophia V; Tolu, Julie; Bindler, Richard

    2015-02-15

    Accumulation records of pollutant metals in peat have been frequently used to reconstruct past atmospheric deposition rates. While there is good support for peat as a record of relative changes in metal deposition over time, questions remain whether peat archives represent a quantitative or a qualitative record. Several processes can potentially influence the quantitative record of which downwashing is particularly pertinent as it would have a direct influence on how and where atmospherically deposited metals are accumulated in peat. The aim of our study was two-fold: first, to compare and contrast the retention of dissolved Pb, Cu, Zn and Ni in peat cores; and second, to test the influence of different precipitation intensities on the potential downwashing of metals. We applied four 'rainfall' treatments to 13 peat cores over a 3-week period, including both daily (2 or 5.3 mm day(-1)) and event-based additions (37 mm day(-1), added over 1h or over a 10h rain event). Two main trends were apparent: 1) there was a difference in retention of the added dissolved metals in the surface layer (0-2 cm): 21-85% for Pb, 18-63% for Cu, 10-25% for Zn and 10-20% for Ni. 2) For all metals and both peat types (sphagnum lawn and fen), the addition treatments resulted in different downwashing depths, i.e., as the precipitation-addition increased so did the depth at which added metals could be detected. Although the largest fraction of Pb and Cu was retained in the surface layer and the remainder effectively immobilized in the upper peat (? 10 cm), there was a smearing effect on the overall retention, where precipitation intensity exerts an influence on the vertical distribution of added trace metals. These results indicate that the relative position of a deposition signal in peat records would be preserved, but it would be quantitatively attenuated. PMID:25460943

  18. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    PubMed Central

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  19. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region.

    PubMed

    Oikawa, P Y; Ge, C; Wang, J; Eberwein, J R; Liang, L L; Allsman, L A; Grantz, D A; Jenerette, G D

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  20. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-11-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  1. The relative influence of local to regional drivers of variation in reef fishes.

    PubMed

    Tuya, F; Wernberg, T; Thomsen, M S

    2011-07-01

    In this study, fishes and habitat attributes were quantified, four times over 1 year, on three reefs within four regions encompassing a c. 6° latitudinal gradient across south-western Australia. The variability observed was partitioned at these spatio-temporal scales in relation to reef fish variables and the influence of environmental drivers quantified at local scales, i.e. at the scale of reefs (the number of small and large topographic elements, the cover of kelp, fucalean and red algae, depth and wave exposure) and at the scale of regions (mean and maximum nutrient concentrations and mean seawater temperature) with regard to the total abundance, species density, species diversity and the multivariate structure of reef fishes. Variation in reef fish species density and diversity was significant at the regional scale, whereas variation in the total abundance and assemblage structure of fishes was also significant at local scales. Spatial variation was greater than temporal variation in all cases. A systematic and gradual species turnover in assemblage structure was observed between adjacent regions across the latitudinal gradient. The cover of red algae within larger patches of brown macroalgae (a biological attribute of the reef) and the number of large topographic elements (a structural attribute of the reef) were correlated with variation observed at local scales, while seawater temperature correlated with variation at the scale of regions. In conclusion, conservation efforts on reef fishes need to incorporate processes operating at regional scales with processes that shape local reef fish communities at local scales. PMID:21722121

  2. Investigation of Health Risks and Their Prevention in the Rapid Climate Changes and the Rise of Pollution of the Atmosphere in the Mountain Region of the North Caucasus

    NASA Astrophysics Data System (ADS)

    Babyakin, Alexander; Polozkov, Igor; Golitsyn, Georgy; Efimenko, Natalia; Zherlitsina, Liubov; Povolotskaya, Nina; Senik, Irina; Chalaya, Elena; Artamonova, Maria; Pogarski, Fedor

    2010-05-01

    The current global climate change is determined by changes in the structure of weather conditions, whose impact on the health of various regions of the planet has not been studied sufficiently. To study this effect on the low-altitude mountains resort of Kislovodsk (southern Russia) multi-factor assessment of the impact of the environment on human health is carried out. There were taking in account atmosphere condition, atmospheric aerosol pollution relationship with atmospheric circulation, the level of pollution matching with different types of weather, and, on the base of analysis of meteopathic reactions (MPR), the extent of their biotropism was revealed. Two sides of weather-climatic influences - specific and nonspecific - are interconnected. They manifest themselves differently in humans with different levels of regulation of vital activity and the adaptive capacity of the organism to the complex environmental effects. This complicates the precise physiological basis of quantitative criteria for the prediction of "biotropic" (adverse) weathers. Nevertheless, clinical observations have shown the existence of the "limiting" physiological bound on the size of medical-meteorological modules (MMM). The reactions of the organism to unfavorable weather factors on the results of a questionnaire monitoring surveillance of patients treated in clinics of Federal State Institution "Pyatigorsk State Research Institute of Curortology, FMBA of Russia" (PSRIC), in comparison with clinical data, have identified various MPR of the organism, the clinical manifestation of which depends on age, sex of the patient, the availability of principal and attendant pathology, reactivity, etc. Analysis of the results of clinical observation, cases of medical aid appealability to the station an ambulance at the sudden ill health, as well as the uptake of advice of sick people among immigrants during their short stay at the resort, and the local population, allowed the first approximation to clarify the criteria for "pathogenicity" of various weather conditions and the factors of air pollution. These criteria were put in a new technology of the Medical Weather Forecast (MWF). In this technology it is proposed to use the integrated Weather Pathogenicity Index (WPI), which is calculated as a weighted average of biotropism indices of various MMM, which include: the dynamics and day to day variability of temperature, pressure and humidity, wind speed, weight content of oxygen and natural air ions in the surface atmosphere, cloudiness, atmospheric phenomena, geomagnetic activity, the ultraviolet index (by UVB solar radiation), the integrated illumination by the sun, the heat conditions of the human. For each of the MMM the five physiological grades of the effects of weather on human adaptation to weather of magnitude and dynamics of WPI are marked out: indifferent, weak, moderate, harsh and overly harsh, according to which the degree of "pathogenicity" of the weather is estimating. Pathogenicity is indicated by quantitative number of medical types of weather (I - a very good weather, II - good weather, III - adverse weather, and IV - a particularly adverse weather). According to the forms of the pressure relief on the sea level, 850 hPa, and 500 hPa, the nature of atmospheric stratification and the presence of atmospheric fronts in the medical types of weather the type of atmospheric circulation is evaluating (anticyclonic - "A", cyclonic - "B", frontal - "C"), which defines a subtype of weather and the possible nature of meteopathia (hypotensive, hypoxic, spastic, etc.). Innovations of the new technology are associated with the introduction of a methodology for the preparation of MWF the modified classifiers to determine the gradation of biotropism degree for various MMM, confirmed by the results of comprehensive empirical medical and climatic studies using dynamic and synoptic weather forecasting making by Hydrometeocenter of Russia and forecast of atmospheric pollution

  3. Differential influence of components resulting from atmospheric-pressure plasma on integrin expression of human HaCaT keratinocytes.

    PubMed

    Haertel, Beate; Straßenburg, Susanne; Oehmigen, Katrin; Wende, Kristian; von Woedtke, Thomas; Lindequist, Ulrike

    2013-01-01

    Adequate chronic wound healing is a major problem in medicine. A new solution might be non-thermal atmospheric-pressure plasma effectively inactivating microorganisms and influencing cells in wound healing. Plasma components as, for example, radicals can affect cells differently. HaCaT keratinocytes were treated with Dielectric Barrier Discharge plasma (DBD/air, DBD/argon), ozone or hydrogen peroxide to find the components responsible for changes in integrin expression, intracellular ROS formation or apoptosis induction. Dependent on plasma treatment time reduction of recovered cells was observed with no increase of apoptotic cells, but breakdown of mitochondrial membrane potential. DBD/air plasma increased integrins and intracellular ROS. DBD/argon caused minor changes. About 100 ppm ozone did not influence integrins. Hydrogen peroxide caused similar effects compared to DBD/air plasma. In conclusion, effects depended on working gas and exposure time to plasma. Short treatment cycles did neither change integrins nor induce apoptosis or ROS. Longer treatments changed integrins as important for influencing wound healing. Plasma effects on integrins are rather attributed to induction of other ROS than to generation of ozone. Changes of integrins by plasma may provide new solutions of improving wound healing, however, conditions are needed which allow initiating the relevant influence on integrins without being cytotoxic to cells. PMID:23936843

  4. Premixed Atmosphere and Convection Influences on Flame Inhibition and Combustion (Pacific)

    NASA Technical Reports Server (NTRS)

    Honda, Linton K.; Ronney, Paul D.

    1997-01-01

    Flame spread over flat solid fuel beds is a useful paradigm for studying the behavior of more complex two-phase nonpremixed flames. For practical applications, two of the most important elements of flame spreading are the effects of (1) the ambient atmosphere (e.g. pressure and composition) and (2) the flow environment on the spread rate and extinction conditions. Concerning (1), studies of flame spread in vitiated air and non-standard atmospheres such as those found in undersea vessels and spacecraft are particularly important for the assessment of fire hazards in these environments as well as determination of the effectiveness of fire suppressants. Concerning (2), the flow environment may vary widely even when no forced flow is present because of buoyancy effects. Consequently, the goal of this work is to employ microgravity (micro g) experiments to extend previous studies of the effects of ambient atmosphere and the flow environment on flame spread through the use of microgravity (micro g) experiments. Because of the considerable differences between upward (concurrent-flow) and downward (opposed-flow) flame spread at 1g (Williams, 1976, Fernandez-Pello, 1984), in this work both upward and downward 1g spread are tested. Two types of changes to the oxidizing atmosphere are considered in this work. One is the addition of sub-flammability-limit concentrations of a gaseous fuel ('partially premixed' atmospheres). This is of interest because in fires in enclosures, combustion may occur under poorly ventilated conditions, so that oxygen is partially depleted from the air and is replaced by combustible gases such as fuel vapors, H2 or CO. Subsequent fire spread over the solid fuel could occur under conditions of varying oxygen and gaseous fuel content. The potential significance of flame spread under vitiated or partially premixed conditions has been noted previously (Beyler, 1984). The second change is the diluent type, which affects the radiative properties of the mixture as well as the Lewis number (Le) of the reactants in the atmosphere, which for oxygen is defined as the thermal diffusivity of the bulk mixture divided by the mass diffusivity of oxygen into the bulk mixture. Understanding the effect of diluent type is desirable because in some undersea and spaceborne habitations, it is desirable to use diluent gases other than nitrogen. Prior experiments have shown that both radiation (Bhattacharjee and Altenkirch, 1993) and Lewis number (Zhang et al, 1992) effects are important in flame spreading problems.

  5. Influence of climate change on atmospheric transport of persistent organic pollutants to the Arctic

    NASA Astrophysics Data System (ADS)

    Hansen, Kaj M.; Chrsitensen, Jesper H.; Brandt, Jørgen

    2014-05-01

    We have applied the Danish Eulerian Hemispheric Model (DEHM) to study the impact of climate change on atmospheric transport of Persistent Organic Pollutants (POPs) to the Arctic as well as investigating the major source areas for the transport to the Arctic. The study represents a sensitivity analysis in order to investigate the response of the model system due to climate change. DEHM is a 3-D atmospheric chemistry-transport model modelling the atmospheric transport of four chemical groups: a group with SOx-NOx-VOC-ozone chemistry, a group with primary particulates group, a mercury chemistry group, and finally a group with Persistent Organic Pollutants (two HCH isomers and 11 PCB congeners). The model domain covers the Northern Hemisphere and thus includes all important source areas for the Arctic. The spatial horizontal resolution of the model system in this work is 150km x 150km and the model includes 20 vertical levels up to approximately 15km above the surface. The model system was run with meteorology obtain from ECHAM5/MPI-OM (SRES A1B scenario) for two decades: 1990-1999 and 2090-2099. In this climate scenario the global mean temperature is predicted to increase by 3ºC by the end of 2100 relative to the period 1971-2000. The same emissions where applied for the two simulations. It is thus possible to investigate the response of DEHM to a changed climate on e.g. the atmospheric transport of POPs to the Arctic. Higher temperature leads to a shift of POPs from the surface media to air. Higher temperatures also lead to larger degradation in air as well as in the surface media. This results in lower modelled masses for the 2090s than for the 1990s within the entire model domain for all modelled species. The higher atmospheric concentrations also result in larger atmospheric transport to the Arctic. For the least chlorinated PCB congeners the increased transport is counteracted by the increased degradation and the result is thus approximately 10% less mass within the Arctic in the 2090s compared to the 1990s. The mass of the more chlorinated PCB congeners with a larger affinity to aerosols (and thus less degradation) is up to 20% higher in the 2090s than in the 1990s. The mass of the HCH isomers within the Arctic is up to 30% higher in the 2090s than in the 1990s due to a larger ice free ocean and increased wet deposition.

  6. Trans-Pacific and regional atmospheric transport of anthropogenic semivolatile organic compounds in the Western United States

    NASA Astrophysics Data System (ADS)

    Primbs, Toby

    The atmospheric transport of anthropogenic semivolatile organic compounds (SOCs) from Asian sources to the Western U.S. was investigated. In addition, the SOC extraction method was optimized. Hansen solubility parameter plots were used to aid in the pressurized liquid extraction (PLE) solvent selection of air sampling media in order to minimize polymeric matrix interferences. To estimate the emissions of anthropogenic semivolatile organic compounds (SOCs) from East Asia and to identify unique SOC molecular markers in Asian air masses, air samples were collected on the island of Okinawa, Japan in Spring 2004. Elevated concentrations of hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and particulate-phase polycyclic aromatic hydrocarbons (PAHs) were attributed to air masses from China. A large proportion of the variation in the current use pesticides, gas-phase PAHs, and polychlorinated biphenyl (PCB) concentrations was explained by meteorology. Using measured PAH, carbon monoxide (CO), and black carbon concentrations and estimated CO and black carbon emission inventories, the emission of 6 carcinogenic particulate-phase PAHs were estimated to be 1518-4179 metric tons/year for all of Asia and 778-1728 metric tons/year for only China. Atmospheric measurements of anthropogenic SOCs were made at Mt. Bachelor Observatory (MBO), located in Oregon's Cascade Range. PAH concentrations at MBO increased with the percentage of air mass time in Asia and, in conjunction with other data, provided strong evidence that particulate-phase PAHs are emitted from Asia and undergo trans-Pacific atmospheric transport to North America. Enhanced HCB, alpha-HCH, and gamma-HCH concentrations also occurred during trans-Pacific atmospheric transport, compared with regional (Western U.S.) air masses during similar time periods. Gas-phase PAH and fluorotelomer alcohol (FTOH) concentrations significantly increased with the percentage of air mass time in California's urban areas, while retene and PCB concentrations increased with the percentage of air mass time in Oregon and during regional fire events. Regional atmospheric transport in the Western U.S. also resulted in enhanced gamma-HCH, dacthal, endosulfan, metribuzin, triallate, trifluralin, and chlorpyrifos concentrations, with episodic concentration enhancements during spring application periods. Elevated SigmaPCB, Sigmachlordane, HCHs, HCB, and trifuralin concentrations were also associated with fires, which may be due to volatization of pesticides deposited to soils and vegetation.

  7. Westerly wind events in the tropical Pacific and their influence on the coupled ocean-atmosphere system: A review

    NASA Astrophysics Data System (ADS)

    Lengaigne, Matthieu; Boulanger, Jean-Philippe; Menkes, Christophe; Delecluse, Pascale; Slingo, Julia

    Observational and modeling aspects about Westerly Wind Events (WWEs) and their influence on the tropical Pacific ocean-atmosphere system are reviewed. WWEs are a large part of the intraseasonal zonal wind activity over the warm pool. They have typical amplitudes of 7 m s-1, zonal width of 20° longitude and duration of about 8 days. Their root causes are often a combination of various factors including the Madden-Julian Oscillation, cold surges from mid-latitudes, tropical cyclones and other mesoscale phenomena. The relationship between WWEs and the ENSO cycle is complex, involving among others the equatorial characteristics of the WWEs, the oceanic background state and the internal atmospheric variability. Both observational and modeling studies demonstrate that WWEs tend to cool the far western Pacific, shift the warm pool eastward and warm the central-eastern Pacific through the generation of Kelvin waves. They are therefore important processes for the central and eastern Pacific warming during the onset and development phase of El Niño. The strong atmospheric feedbacks that are likely to be generated by the ocean response to WWEs even suggest that a single WWE is capable of establishing the conditions under which El Niño can occur. The important role played by WWEs in the evolution and amplitude of recent El Niño events may therefore strongly limit the predictability of El Niño.

  8. Influence of atmospheric static stability and meridional temperature gradient on the growth in amplitude of synoptic-scale unstable waves

    NASA Astrophysics Data System (ADS)

    Soldatenko, S. A.

    2014-11-01

    Observations and results of numerical experiments with climate models under different green-house-gas emission scenarios point to a reconstruction of the thermal and circulation atmospheric regime induced by global climate changes. In particular, an increase in atmospheric static stability, a poleward shift of midlatitude storm tracks, a decrease in the frequency of extratropical cyclones, and a change in their intensity are found at tropical and middle latitudes. This paper, using a simplified idealized model of baroclinic instability, investigates the influence of small variations in the basic atmospheric parameters governing the development of baroclinic instability, namely, static stability and the vertical quasi-zonal flow velocity shear induced by a meridional temperature gradient, on variations in the growth rate of the amplitude of synopticscale unstable waves. Analytical expressions are derived for absolute and relative sensitivity functions to estimate the absolute and relative contribution of variations in the static stability and the vertical flow velocity shear to a change in the growth rate of the amplitude of unstable modes.

  9. Influence of Atmospheric Variations on Photovoltaic Performance and Modeling Their Effects for Days with Clear Skies: Preprint

    SciTech Connect

    Marion, B.

    2012-06-01

    Although variation in photovoltaic (PV) performance is predominantly influenced by clouds, performance variations also exist for days with clear skies with different amounts of atmospheric constituents that absorb and reflect different amounts of radiation as it passes through the earth's atmosphere. The extent of the attenuation is determined by the mass of air and the amounts of water vapor, aerosols, and ozone that constitute the atmosphere for a particular day and location. Because these constituents selectively absorb radiation of particular wavelengths, their impact on PV performance is sensitive to the spectral response of the PV device. The impact may be assessed by calculating the spectral mismatch correction. This approach was validated using PV module performance data at the National Renewable Energy Laboratory (NREL) for summer, fall, and winter days with clear skies. The standard deviation of daily efficiencies for single-crystal Si, a-Si/a-Si/a-Si:Ge, CdTe, and CIGS PV modules were reduced to 0.4% to 1.0% (relative) by correcting for spectral mismatch, temperature, and angle-of-incidence effects.

  10. The influence of vegetation-atmosphere-ocean interaction on climate during the mid-holocene

    PubMed

    Ganopolski; Kubatzki; Claussen; Brovkin; Petoukhov

    1998-06-19

    Simulations with a synchronously coupled atmosphere-ocean-vegetation model show that changes in vegetation cover during the mid-Holocene, some 6000 years ago, modify and amplify the climate system response to an enhanced seasonal cycle of solar insolation in the Northern Hemisphere both directly (primarily through the changes in surface albedo) and indirectly (through changes in oceanic temperature, sea-ice cover, and oceanic circulation). The model results indicate strong synergistic effects of changes in vegetation cover, ocean temperature, and sea ice at boreal latitudes, but in the subtropics, the atmosphere-vegetation feedback is most important. Moreover, a reduction of the thermohaline circulation in the Atlantic Ocean leads to a warming of the Southern Hemisphere. PMID:9632385

  11. Ocean-atmosphere coupling at the Brazil-Malvinas Confluence region based on in situ, satellite and numerical model data

    NASA Astrophysics Data System (ADS)

    Casagrande, F.; Souza, R.; Pezzi, L.

    2013-05-01

    In the Southwest Atlantic close to 40oS, the meeting of two ocean currents with distinct characteristics, the Brazil Current (BC), warm and saline, and the Malvinas Current (MC), cold and low salinity, resulting in strong activity marked by the formation of mesoscale eddies, this region is known as Brazil Malvinas Confluence (BMC). The INTERCONF project (Ocean Atmosphere Interaction over the region of CBM) perfoms since the 2002 data collection in situ radiosondes and XBTs onboard the Oceanographic Support Ship Ary Rongel during its trajectory of Brazil to the Antarctic continent. This paper analyzes the thermal contrast and ocean atmosphere coupling on the ocean front from the INTERCONF data, and compares the results to satellite data (QuikSCAT) and numerical models (Eta-CPTEC / INPE). The results indicate that the Sea Surface Temperature (SST) is driving the atmosphere, on the warm waters of the BC occurs an intensification of the winds and heat fluxes, and the reverse occurs on the cold waters of the MC. The data collected in 2009 include the presence of a warm core eddy (42 oS to 43.1 oS) which recorded higher values of heat fluxes and wind speed in relation to its surroundings. On the warm core eddy wind speed recorded was about 10 m.s-1, while on the BC and MC was approximately 7 m.s-1 and 2 m.s-1, respectively. Satellite data and numerical model tends to overestimate the wind speed data in the region in relation to data collected in situ. The heat flux data from the numerical model tend to increase over the warm waters and cold waters on the decline, though the amounts recorded by the model have low correlation.

  12. Influence of gaseous contaminants in the atmosphere of ISS on growth and development of higher plants

    NASA Astrophysics Data System (ADS)

    Levinskikh, Margarita; Sychev, Vladimir; Podolsky, Igor; Moukhamedieva, Lana; Gostimskiy, Sergey; Bingham, Gail

    Continues exploitation of pressurized manned objects revealed that artificial gaseous atmosphere is a multi-component mixture containing adverse micro-dirt consisted of 14 classes of chemical compounds (Moukhamedieva, 2003). Dynamics of descendant process depend on duration of pressurized object utilization, resources of life support (e.g. level of closeness), parameters of microclimate and experimental tasks conducted by a crew. Previously it was shown that composition of gas environment of the space station remarkably altered growth and development of higher plants (Levinskikh et al., 2000). Specifically, it was found that the main changes in productivity and morphometric characteristics of the spaceflight plants of superdwarf wheat were caused by phytotoxic effect of ethylene (1,1-2,0 mg/m3) in the atmosphere of MIR orbital station. From 2003 to April, 2007 we have conducted 7 experiments focused on cultivation of dwarf peas in space greenhouse LADA onboard International Space Station (ISS-6-10, 12, 14). Results of the first 5 experiments showed that characteristics of growth and development of the peas planted in the space greenhouse had no differences if compared with ground control variants. In the similar experiments with peas during ISS-12 and ISS-14 it was found that total and seed productions of the plants were lower than ones of the previous experiments and ones of the ground controls. Cytological analysis of roots of the space seeds for the first time revealed significant increase of chromosomal aberrations in comparison with laboratory controls Analysis of total contamination of the atmosphere of the ISS by gaseous dirt showed consistent (starting from ISS-11) increasing of the toxicity coefficient (Kt). W e suppose that the accumulation of pollutant in the atmosphere of ISS is the main reason causing general decreasing of productivity and increasing of the number of chromosomal aberrations in the peas cultivated in space greenhouse LADA at the stage of ISS-12 and ISS-14.

  13. Influence of atmospheric correction on image classification for irrigated agriculture in the Lower Colorado River Basin

    NASA Astrophysics Data System (ADS)

    Wei, X.

    2012-12-01

    Atmospheric correction is essential for accurate quantitative information retrieval from satellite imagery. In this paper, we applied the atmospheric correction algorithm, Second Simulation of a Satellite Signal in the Solar Spectrum (6S) radiative transfer code, to retrieve surface reflectance from Landsat 5 Thematic Mapper (TM) imagery for the Palo Verde Irrigation District (PVID) within the lower Colorado River basin. The 6S code was implemented with the input data of visibility, aerosol optical depth, pressure, temperature, water vapour, and ozone from local measurements. The 6S corrected image of PVID was classified into the irrigated agriculture of alfalfa, cotton, melons, corn, grass, and vegetables. We performed multiple classification methods of maximum likelihood, fuzzy means, and object-oriented classification methods. Using field crop type data, we conducted accuracy assessment for the results from 6S corrected image and uncorrected image and found a consistent improvement of classification accuracy for 6S corrected image. The study proves that 6S code is a robust atmospheric correction method in providing a better simulation of surface reflectance and improving image classification accuracy.;

  14. Direct human influence on atmospheric CO2 seasonality from increased cropland productivity

    NASA Astrophysics Data System (ADS)

    Gray, Josh M.; Frolking, Steve; Kort, Eric A.; Ray, Deepak K.; Kucharik, Christopher J.; Ramankutty, Navin; Friedl, Mark A.

    2014-11-01

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50 per cent over the past 50 years. This increase has been linked to changes in temperate, boreal and arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind the observed changes in atmospheric CO2 seasonality remain unclear. Here we use production statistics and a carbon accounting model to show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as a quarter of the observed changes in atmospheric CO2 seasonality. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240 per cent between 1961 and 2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 petagrams. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the midwestern United States and northern China. Maize, wheat, rice, and soybeans account for about 68 per cent of extratropical dry biomass production, so it is likely that the total impact of increased agricultural production exceeds the amount quantified here.

  15. Direct human influence on atmospheric CO2 seasonality from increased cropland productivity.

    PubMed

    Gray, Josh M; Frolking, Steve; Kort, Eric A; Ray, Deepak K; Kucharik, Christopher J; Ramankutty, Navin; Friedl, Mark A

    2014-11-20

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50 per cent over the past 50 years. This increase has been linked to changes in temperate, boreal and arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind the observed changes in atmospheric CO2 seasonality remain unclear. Here we use production statistics and a carbon accounting model to show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as a quarter of the observed changes in atmospheric CO2 seasonality. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240 per cent between 1961 and 2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 petagrams. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the midwestern United States and northern China. Maize, wheat, rice, and soybeans account for about 68 per cent of extratropical dry biomass production, so it is likely that the total impact of increased agricultural production exceeds the amount quantified here. PMID:25409830

  16. Hydration-Influenced Sorption of Organic Compounds by Model and Atmospheric Humic- Like Substances (HULIS)

    NASA Astrophysics Data System (ADS)

    Graber, E.; Taraniuk, I.; Rudich, Y.

    2008-12-01

    Atmospheric humic-like substances (HULIS) constitute a major fraction of the water soluble organic carbon portion of aerosol particles. We investigated sorption and desorption of water and two model organic contaminants (toluene and benzyl alcohol) on HULIS and a standard humic substance (Suwannee River fulvic acid; SRFA) under conditions of varying relative humidity using a quartz crystal microbalance. Simultaneous sorption of water and benzyl alcohol (capable of specific interactions) on HULIS and SRFA shows significant, humidity-dependent, cooperative sorption of benzyl alcohol at intermediate levels of water activity, as well as a dependence of sorption distribution coefficient on the wetting-drying pathway. In contrast, sorption of toluene (capable of only non-specific interactions) was humidity-independent. Atmospheric HULIS is thus found to have many sorption features in common with terrestrial and aquatic humic substances and soil organic matter. These features are consistent with the Link Solvation Model (LSM) concept, whereby water assists in cooperative sorption of specifically-interacting compounds with the organic matter sorbent, and subsequent changes in sorbent structure result in sorption hysteresis. Sorption of compounds capable of only non-specific interactions is unaffected by hydration status. Such sorption features can lead to considerable uncertainty in predicting and modeling transport of organic pollutants in the atmosphere.

  17. Influence of solar forcing, climate variability and modes of low-frequency atmospheric variability on summer floods in Switzerland

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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 a new index of summer flood damage that considers severe and catastrophic summer floods in Switzerland between 1800 and 2009, and explores the influence of external forcings on flood frequencies. In addition, links between floods and low-frequency atmospheric variability 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 low-frequency atmospheric variability modes shows that Switzerland lies close to the border of the principal summer mode. 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 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 variability pattern related to the major floods occurred over the period from 1800 to 2009; the summer principal mode persists in the negative phase during the last cool pulses of the Little Ice Age (1817-1851 and 1881-1927 flood clusters), whereas the positive phases of the mode prevail during the warmer climate of the last 4 decades (flood clusters from 1977 to present).

  18. Influence of seasonal soil moisture memory on land-atmosphere interactions: a coupled mesoscale modeling study of the 2006 Southern Great Plains drought

    NASA Astrophysics Data System (ADS)

    Zaitchik, B. F.; Santanello, J. A.; Kumar, S.; Peters-Lidard, C. D.

    2011-12-01

    The Southern Great Plains (SGP) of North America is a region of active land-atmosphere coupling. This coupling is understood to be particularly pronounced under dry conditions and, on a seasonal scale, is believed to include drought-enhancing feedbacks that pose a challenge to seasonal weather prediction. Here we employ the NASA Unified Weather Research and Forecast (NU-WRF) modeling system to investigate the role of two hypothesized mechanisms of land-atmosphere feedbacks under severe drought: reduced evaporative fraction due to low soil moisture and reduced surface energy due to enhanced albedo. The presence of the Land Information System (LIS) within NU-WRF offers a powerful tool for executing these numerical experiments. It was found that representation of the seasonal evolution of soil moisture within the model (i.e., "soil moisture memory") led to warmer simulated near-surface air temperatures, greater simulated sensible heat flux, higher simulated lifting condensation level deficit and reduced simulated cloud water content relative to simulations without soil moisture memory across drought-affected regions of the SGP. Soil moisture and temperature variability in the soil moisture memory simulation corresponded more closely to available observations. Simulations that included representation of soil moisture influence on surface albedo anomaly exhibited lower net available radiation, cooler near-surface air temperatures, and a shallow daytime planetary boundary layer relative to simulations with climatological surface albedo estimates. Simulations with active albedo resulted in less precipitation over most of the study region, suggesting that an albedo feedback was a plausible drought intensifying mechanism the SGP in 2006. In the relatively wet summer of 2007, soil moisture and albedo manipulations both had smaller impacts on model results. These results suggest that NU-WRF with LIS provides realistic seasonal-scale simulations in the SGP in both a wet year and a dry year, that model performance is improved when soil moisture and albedo anomalies were included, that land-atmosphere coupling is stronger under dry conditions, and that in 2006, combined feedbacks due to albedo and soil moisture had a small but significant impact on the evolution of SGP drought.

  19. Climate responses to a doubling of atmospheric carbon dioxide for a climatically vulnerable region

    E-print Network

    Snyder, Mark A.

    temperature increasing everywhere in the region annually (up to 3.8°C), and in every month, with the greatest monthly surface warming at high elevations. Snow accumulation decreased everywhere, and precipitation) [Cal. Dept. of Water Resources, 199

  20. The influence of the growth of the Dallas/Fort Worth (DFW) Metroplex on regional precipitation patterns 

    E-print Network

    Nordfelt, Anna Marie

    2009-05-15

    Due to the effects urbanization has on land-use and land cover change (LULC), urban areas have a major influence on the environment. The strong coupling between the land and atmosphere can alter the microclimatology of cities and their surrounding...

  1. Characteristics Of Atmospheric Dry Deposition Of Metals To The Region Of Lake Asan And Sapgyo, Korea

    NASA Astrophysics Data System (ADS)

    Han, J.; Shin, H.; Lee, M.; Lim, Y.; Seo, M.; Jung, I.

    2008-12-01

    Environment includes a multi-media such as air, surface water, soil, underground water and ecosystem. Some pollutants transfer among a multi-media, posing serious threat to humans, animals and plants. Pollutants released into the environment remain for long times and transport long distances while going through physical and chemical interactions such as transports between multi-media ; air, water and soil, deposition, and absorption and release from organisms. This study assessed the amount of heavy metals transferred from air to water and soil using dry deposition plate and water surface sampler during spring (June 13 ~ 21, 2007) and winter (October 23 ~ 30 in 2007) at 9 locations including Dangjin, Pyeongtaek and Asan. Micro-Orifice Uniform Deposit Impactor, MOUDI was used to confirm the size distribution. The measured heavy metal deposition flux was compared with the expectation obtained with deposition model. In addition, amount of heavy metal deposition at Asan and Sapgyo lakes were evaluated to verify the water pollution state driven by atmospheric deposition. Atmospheric dry deposition flux of metals are 133.92 microgram m-2 day-1, 44.01 microgram m-2 day-1, 0.915 microgram m-2 day-1, and 0.175 microgram m-2 day-1 during spring, and 72.86 microgram m-2 day- 1, 88.14 microgram m-2 day-1, 0.991 microgram m-2 day-1, and 0.189 microgram m-2 day-1 during fall, for lead, nickel, arsenic, and cadmium, respectively. It is required to re- calculation the dry deposition flux by land use type due to possibility of underestimating the flux in case of using grease surrogate surface having low surface roughness. The cadmium, lead, and arsenic size distribution was mono-modal with the peaks in the 0.65 ~ 1.1 micrometer size range in the fine mode showing sharp peak in the condensation submode especially for cadmium and lead because of effect of primary emission. The nickel size distribution was bimodal, a typical size distribution for an urban atmosphere, showing sharp peak in the condensation submode affected by primary emission and coarse mode. Total atmospheric dry deposition loads of metals to the Lake Asan and Sapgyo are 1272.6 ~ 1764.1 g day-1, 655.3 ~ 908.3 g day-1, and 137.2 ~ 190.1 g day-1 during spring, and 6914.1 ~ 9583.8 g day-1, 849.2 ~ 1177.1 g day-1, and 79.2 ~ 109.8 g day-1 during fall, for lead, nickel, and arsenic, respectively. Total flux of atmospheric pollution could be calculated later by adding the result of wet deposition which is the major atmospheric transport of pollution.

  2. Inferences on the thermodynamic characteristics of a star from the observed distinctive radial sequences of the distinctive atmospheric regions comprising that stellar atmosphere

    SciTech Connect

    Not Available

    1983-01-01

    The implications of observational findings on atmospheric and subatmospheric taxonomy, diagnostics, and modeling are explored. The correlations between distinctive radial sequences in stellar atmospheres and the thermodynamic properties of the stars in which they appear are discussed.

  3. Differences in satellite CO2 data coverage and their influence on regional flux constraints

    NASA Astrophysics Data System (ADS)

    Takagi, H.; Andres, R. J.; Belikov, D. A.; Boesch, H.; Bril, A.; Butz, A.; Inoue, M.; Morino, I.; Oda, T.; O'Dell, C.; Oshchepkov, S.; Parker, R.; Saito, M.; Uchino, O.; Valsala, V.; Yokota, T.; Yoshida, Y.; Maksyutov, S. S.

    2014-12-01

    Inverse modeling of atmospheric transport is a technique that systematically searches for space-time distributions of trace gas fluxes that yield modeled atmospheric concentrations close to observations. This technique has been employed for the estimation of surface CO2 flux distributions in better understanding the mechanisms of the global carbon cycle. As this inference relies on observations, several studies were conducted in the past to see the sensitivity of flux estimates to the expansion of surface monitoring networks over time and the choice of data-providing sites in the estimation. These studies showed that changes in the geographical distribution of the surface data have a large impact on regional-scale flux estimates. With the advent of the Greenhouse gases Observing SATellite (GOSAT) in early 2009, the spatial coverage by the surface monitoring networks can now be widely expanded with the spaceborne soundings, from which column-averaged CO2 concentrations (XCO2) are retrieved. These GOSAT-based XCO2 retrievals are made available by five research groups, and their precisions have been reported to be below 2 ppm level. Where they coincide, the five XCO2 retrievals (all biases corrected) agree within one standard deviation of less than 1 ppm. On one hand, the extent that each of the XCO2 retrieval data product covers the surface differs from one to another, owing to differences in the retrieval algorithms and data screening criteria, and the coverage differences were found to be dependent on geographical locations. We investigated the extent to which these data-coverage differences alter constraints on individual regional CO2 flux estimates. For this, we used a diagnostic known as the resolution kernel, which quantifies how well the regional flux estimates can be resolved by the observations. The inversion system used here is the same as what is used to generate the GOSAT Level 4 regional flux data product, and consists of NIES 08.1i transport model and the Kalman Smoother optimization scheme. Here, we will present the results for several representative regions including eastern Asia that are under-sampled by the surface networks but well-observed by the satellite. We will also touch briefly on the latest GOSAT Level 4 CO2 data product.

  4. Near-surface climate of the Antarctic Peninsula as simulated by a high-resolution regional atmospheric climate model

    NASA Astrophysics Data System (ADS)

    van Wessem, M.; Reijmer, C.; van den Broeke, M. R.

    2014-12-01

    The latest polar version of the regional atmospheric climate model RACMO2 (RACMO2.3) has been applied to the Antarctic Peninsula. Recently, the model physics have been updated, which resulted in a significant improvement in its performance, at 27 km resolution, over East and West Antarctica, in terms of surface energy fluxes and surface mass budget. Here we present results from a climatological run at 5.5 km over the AP for the period 1979-2013, in which RACMO2.3 is forced by ERA-Interim atmospheric and ocean surface fields and includes an AP surface topography based on state of the art digital elevation models. RACMO2.3 resolves the extremely large gradients over the Antarctic Peninsula mountain spine, in terms of surface and 2 meter temperature, which are caused by the persistent atmospheric westerly winds. We evaluate the model results by comparing them to temperature series from manned and automatic weather stations, vertical profiles from balloon soundings and surface energy balance measurements from three automatic weather stations. Results show that RACMO2.3 performs well in terms of surface and 2 m temperatures, 10 m wind speed/direction, but we also identify some significant biases in the downwelling fluxes of shortwave- and longwave radiation, related to clouds. These biases largely compensate each other, however, so that melt energy fluxes are resolved with reasonable accuracy.

  5. Structures and characteristics of the windy atmospheric boundary layer in the South China Sea region during cold surges

    NASA Astrophysics Data System (ADS)

    Cheng, Xue-Ling; Huang, Jian; Wu, Lin; Zeng, Qing-Cun

    2015-06-01

    An observational analysis of the structures and characteristics of a windy atmospheric boundary layer during a cold air outbreak in the South China Sea region is reported in this paper. It is found that the main structures and characteristics are the same as during strong wind episodes with cold air outbreaks on land. The high frequency turbulent fluctuations (period <1 min) are nearly random and isotropic with weak coherency, but the gusty wind disturbances (1 minatmospheric boundary layer at sea, compared with that over land, there are some pronounced differences: (1) the average horizontal speed is almost independent of height, and the vertical velocity is positive in the lower marine atmospheric boundary layer; (2) the vertical flux of horizontal momentum is nearly independent of height in the low layer indicating the existence of a constant flux layer, unlike during strong wind over the land surface; (3) the kinetic energy and friction velocity of turbulent fluctuations are larger than those of gusty disturbances; (4) due to the independence of horizontal speed to height, the horizontal speed itself (not its vertical gradient used over the land surface) can be used as the key parameter to parameterize the turbulent and gusty characteristics with high accuracy.

  6. Turbulence structure of the atmosphere in a region of complex terrain and near to a major industrial installation

    SciTech Connect

    Robinson, L.; Teasdale, I.

    1996-12-31

    The Sellafield nuclear reprocessing plant in Cumbria discharges a variety of pollutants to both the marine environment and the atmosphere. Understanding the dispersion of this effluence is of prime importance for the industry, which must demonstrate safety to national regulatory bodies. Accurate modelling of the air flow in the region is one of the key ingredients towards correct prediction of the ground level concentrations of emissions. Work is being carried out to assess the suitability of the computer code FLOWSTAR for the task of predicting the atmospheric flow. Its predictions include means of the turbulent statistics within the boundary layer of the atmosphere. This paper will concentrate on the comparison of the predictions of these turbulence statistics at key points with the values measured by sonic anemometry. It is the turbulence, quantified by the standard deviations {sigma}{sub u}, {sigma}{sub v} and {sigma}{sub w} of the wind vector`s components that is responsible for the local dispersion of pollution and for inducing many other boundary layer changes. The high frequency variation in the wind vector brings about the necessity for rapid response equipment such as the sonic anemometer.

  7. A simple algorithm to estimate the effective regional atmospheric parameters for thermal-inertia mapping

    USGS Publications Warehouse

    Watson, K.; Hummer-Miller, S.

    1981-01-01

    A method based solely on remote sensing data has been developed to estimate those meteorological effects which are required for thermal-inertia mapping. It assumes that the atmospheric fluxes are spatially invariant and that the solar, sky, and sensible heat fluxes can be approximated by a simple mathematical form. Coefficients are determined from least-squares method by fitting observational data to our thermal model. A comparison between field measurements and the model-derived flux shows the type of agreement which can be achieved. An analysis of the limitations of the method is also provided. ?? 1981.

  8. Infrared emissions of H3(+) in the atmosphere of Jupiter in the 2. 1 and 4. 0 micron region

    SciTech Connect

    Miller, S.; Tennyson, J.; Joseph, R.D. Hawaii Univ., Honolulu )

    1990-09-01

    Infrared spectra of the Jovian atmosphere around 2.1 and 4.0 microns, measured using the NASA Infrared Telescope Facility at Mauna Kea, Hawaii, are presented. The observations were made between February 6 and 8, 1990. In both spectral regions, features attributable to H3(+) were visible. The intensity ratio of lines in the 2 and 4 microns regions measured from the northern auroral hot spot during the same night leads to a rovibrational temperature of 1100 + or - 100 K for this molecular ion, close to a previous measurement of the rotational temperature of 1099 + or - 100 K. This indicates that the upper energy levels are being populated by purely thermal processes, rather than by resonant energy exchange. The para-H3(+) fractional abundance of 0.58 determined by previous workers is found to be consistent with this study. The time dependency of the H3(+) emission phenomena is confirmed. 9 refs.

  9. Mesoscale atmospheric flow-field simulations for air quality modeling over complex terrain region of Ranchi in eastern India using WRF

    NASA Astrophysics Data System (ADS)

    Madala, Srikanth; Satyanarayana, A. N. V.; Srinivas, C. V.; Kumar, Manoj

    2015-04-01

    In the present study mesoscale meteorological flow and planetary boundary layer (PBL) parameters over the complex topographic region of Jharkhand state of tropical India are simulated using high resolution Advanced Research WRF (ARW) mesoscale model to study their role in the air pollution dispersion characteristics using a Lagrangian Particle Dispersion Model (FLEXPART). Eight fair weather days in different seasons (winter, pre-monsoon, monsoon, and post-monsoon) are chosen. Sensitivity experiments are conducted with two non-local [Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2)] and three local turbulence kinetic energy (TKE) closure [Mellor- Yamada Nakanishi and Niino Level 2.5 PBL (MYNN2), Mellor-Yamada-Janjic (MYJ), and quasi-normal scale elimination (QNSE)] PBL parameterisations to study the evolution of PBL parameters and thermodynamic structure. Simulated parameters are validated with available in situ meteorological observations at three stations in the study region. Results indicate that the low-level flow field is highly influenced by the topography and widely varies in different seasons. Simulated vertical PBL structure varied across seasons with shallow boundary layers (1-1.7 km) during winter, monsoon and post-monsoon seasons, deep mixed layers (2-2.7 km) in pre-monsoon season. Simulations in various seasons revealed that ACM2 followed by MYNN2 and YSU reproduced various PBL features such as topographic flows, surface layer fluxes, meteorological variables and the thermo-dynamical structure reasonably well indicating the suitability of the above PBL schemes for air quality simulations over the region. This is corroborated with the error statistics as well. Simulations with FLEXPART using ARW derived meteorology revealed higher dilution potential of the atmosphere in monsoon and pre-monsoon compared to post monsoon and winter seasons over the region. Results also indicate the ACM2, MYNN2 and YSU produce relatively larger dispersion than the QNSE and MYJ.

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

    PubMed Central

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

    2014-01-01

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

  11. Changes in atmospheric CO2 - Influence of the marine biota at high latitude

    NASA Technical Reports Server (NTRS)

    Knox, F.; Mcelroy, M. B.

    1984-01-01

    Approximately half of the nitrogen and phosphorus entering deep waters of the contemporary ocean are transported from the surface in inorganic form as preformed nutrients. A simple model for ocean chemistry is presented and shown to account for the present level of atmospheric CO2. Fluctuations in preformed nutrients, modulated by changes in insolation and circulation at high latitudes, can result in significant variations in CO2. It is suggested that these changes may account for the apparent control on climate exercised by secular variations in the orbital parameters of the earth.

  12. Influence of reservoirs on solute transport: A regional-scale approach

    USGS Publications Warehouse

    Kelly, V.J.

    2001-01-01

    Regional transport of water and dissolved constituents through heavily regulated river systems is influenced by the presence of reservoirs. Analysis of seasonal patterns in solute fluxes for salinity and nutrients indicates that in-reservoir processes within large storage reservoirs in the Rio Grande and Colorado basins (southwestern USA) are superimposed over the underlying watershed processes that predominate in relatively unregulated stream reaches. Connectivity of the aquatic system with the landscape is apparently disrupted by processes within the reservoir systems; these processes result in large changes in characteristics for solute transport that persist downstream in the absence of significant inputs. Additionally, reservoir processes may be linked for upstream/downstream reservoirs that are located relatively close in a series. In contrast, the regional effect of in-reservoir processes is negligible for solute transport through run-of-river reservoirs in the lower Columbia River (northwestern USA).

  13. Atmospheric ammonia and its impacts on regional air quality over the megacity of Shanghai, China.

    PubMed

    Wang, Shanshan; Nan, Jialiang; Shi, Chanzhen; Fu, Qingyan; Gao, Song; Wang, Dongfang; Cui, Huxiong; Saiz-Lopez, Alfonso; Zhou, Bin

    2015-01-01

    Atmospheric ammonia (NH3) has great environmental implications due to its important role in ecosystem and global nitrogen cycle, as well as contribution to secondary particle formation. Here, we report long-term continuous measurements of NH3 at different locations (i.e. urban, industrial and rural) in Shanghai, China, which provide an unprecedented portrait of temporal and spatial characteristics of atmospheric NH3 in and around this megacity. In addition to point emission sources, air masses originated from or that have passed over ammonia rich areas, e.g. rural and industrial sites, increase the observed NH3 concentrations inside the urban area of Shanghai. Remarkable high-frequency NH3 variations were measured at the industrial site, indicating instantaneous nearby industrial emission peaks. Additionally, we observed strong positive exponential correlations between NH4(+)/(NH4(+)+NH3) and sulfate-nitrate-ammonium (SNA) aerosols, PM2.5 mass concentrations, implying a considerable contribution of gas-to-particle conversion of ammonia to SNA aerosol formation. Lower temperature and higher humidity conditions were found to favor the conversion of gaseous ammonia to particle ammonium, particularly in autumn. Although NH3 is currently not included in China's emission control policies of air pollution precursors, our results highlight the urgency and importance of monitoring gaseous ammonia and improving its emission inventory in and around Shanghai. PMID:26514559

  14. Atmospheric ammonia and its impacts on regional air quality over the megacity of Shanghai, China

    NASA Astrophysics Data System (ADS)

    Wang, Shanshan; Nan, Jialiang; Shi, Chanzhen; Fu, Qingyan; Gao, Song; Wang, Dongfang; Cui, Huxiong; Saiz-Lopez, Alfonso; Zhou, Bin

    2015-10-01

    Atmospheric ammonia (NH3) has great environmental implications due to its important role in ecosystem and global nitrogen cycle, as well as contribution to secondary particle formation. Here, we report long-term continuous measurements of NH3 at different locations (i.e. urban, industrial and rural) in Shanghai, China, which provide an unprecedented portrait of temporal and spatial characteristics of atmospheric NH3 in and around this megacity. In addition to point emission sources, air masses originated from or that have passed over ammonia rich areas, e.g. rural and industrial sites, increase the observed NH3 concentrations inside the urban area of Shanghai. Remarkable high-frequency NH3 variations were measured at the industrial site, indicating instantaneous nearby industrial emission peaks. Additionally, we observed strong positive exponential correlations between NH4+/(NH4++NH3) and sulfate-nitrate-ammonium (SNA) aerosols, PM2.5 mass concentrations, implying a considerable contribution of gas-to-particle conversion of ammonia to SNA aerosol formation. Lower temperature and higher humidity conditions were found to favor the conversion of gaseous ammonia to particle ammonium, particularly in autumn. Although NH3 is currently not included in China’s emission control policies of air pollution precursors, our results highlight the urgency and importance of monitoring gaseous ammonia and improving its emission inventory in and around Shanghai.

  15. Atmospheric surface layer responses to the extreme lightning day in plateau region in India

    NASA Astrophysics Data System (ADS)

    Dwivedi, Arun K.; Chandra, Sagarika; Kumar, Manoj; Kumar, Sanjay; Kiran Kumar, N. V. P.

    2014-12-01

    This paper discusses the observations of the atmospheric surface layer (ASL) parameters during the lightning event. During this event behaviour of surface layer parameters has been observed. Other derived parameters like Monin-Obukhov stability parameter (z/L), turbulent kinetic energy (TKE), momentum flux (MF) and sensible heat flux (SHF) have also been considered during this stochastic phenomenon. Characteristics of these surface layer parameters have been analysed during lightning period and compared with the clear weather day. During the peak period of the lightning, the incoming solar irradiance was reduced by one third of its normal value, resulting in an air-temperature decrement near the surface in the range of 4 °C to 6 °C. In addition to that a significant reduction in energy exchanges between surface and lower lying atmosphere (viz. TKE, MF and SHF), has also been observed. The rate of instantaneous decay in solar irradiance and SHF from the first strike to its peak strike time was larger than that seen during clear day hours. The normalized standard deviations of wind components during clear day were studied using Monin-Obukhov similarity theory (MOST) and the results have been compared with earlier studies reported in the literature.

  16. Atmospheric ammonia and its impacts on regional air quality over the megacity of Shanghai, China

    PubMed Central

    Wang, Shanshan; Nan, Jialiang; Shi, Chanzhen; Fu, Qingyan; Gao, Song; Wang, Dongfang; Cui, Huxiong; Saiz-Lopez, Alfonso; Zhou, Bin

    2015-01-01

    Atmospheric ammonia (NH3) has great environmental implications due to its important role in ecosystem and global nitrogen cycle, as well as contribution to secondary particle formation. Here, we report long-term continuous measurements of NH3 at different locations (i.e. urban, industrial and rural) in Shanghai, China, which provide an unprecedented portrait of temporal and spatial characteristics of atmospheric NH3 in and around this megacity. In addition to point emission sources, air masses originated from or that have passed over ammonia rich areas, e.g. rural and industrial sites, increase the observed NH3 concentrations inside the urban area of Shanghai. Remarkable high-frequency NH3 variations were measured at the industrial site, indicating instantaneous nearby industrial emission peaks. Additionally, we observed strong positive exponential correlations between NH4+/(NH4++NH3) and sulfate-nitrate-ammonium (SNA) aerosols, PM2.5 mass concentrations, implying a considerable contribution of gas-to-particle conversion of ammonia to SNA aerosol formation. Lower temperature and higher humidity conditions were found to favor the conversion of gaseous ammonia to particle ammonium, particularly in autumn. Although NH3 is currently not included in China’s emission control policies of air pollution precursors, our results highlight the urgency and importance of monitoring gaseous ammonia and improving its emission inventory in and around Shanghai. PMID:26514559

  17. Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions: Part I Africa and India

    SciTech Connect

    Sud, Yogesh C.; Wilcox, Eric; Lau, William K.; Walker, Greg K.; Liu, Xiaohong; Nenes, Athanasios; Lee , Dongmin; Kim, K. - M.; Zhou, Yaping; Bhattacharjee, P. S.

    2009-10-23

    Version-4 of the Goddard Earth Observing System (GEOS-4) General Circulation Model (GCM) was employed to assess the influence of potential changes in aerosols on the regional circulation, ambient temperatures, and precipitation in four selected regions: India and Africa (current paper), as well as North and South America (companion paper). Ensemble-simulations were carried out with the GCM to assess the aerosol direct and indirect effects, hereafter ADE and AIE. Each simulation was started from the NCEP-analyzed initial conditions for May 1 and was integrated through May-June-July-August of each year: 1982-1987 to provide an ensemble set of six simulations. In the first set, called the baseline experiment (#1), climatological aerosols were prescribed. The next two experiments (#2 and #3) had two sets of simulations each: one with 2X and another with 1/2X the climatological aerosols over each of the four selected regions. In experiment#2, the anomaly regions were advectively restricted (AR), i.e., the large-scale prognostic fields outside the aerosol anomaly regions were prescribed while in experiment#3, the anomaly regions were advectively Interactive (AI) as is the case in a normal GCM integrations, but with the same aerosols anomalies as in experiment #2. Intercomparisons of circulation, diabatic heating, and precipitation difference fields showed large disparities among the AR and AI simulations, which raised serious questions about the AR assumption, commonly invoked in regional climate simulation studies. Consequently AI simulation mode was chosen for the subsequent studies. Two more experiments (#4 and #5) were performed in the AI mode in which ADE and AIE were activated one at a time. The results showed that ADE and AIE work in concert to make the joint influences larger than sum of each acting alone. Moreover, the ADE and AIE influences were vastly different for the Indian and Africa regions, which suggest an imperative need to include them rationally in climate models. We also found that the aerosol induced increase of tropical cirrus clouds would potentially offset any cirrus thinning that may occur due to global warming in response to CO2 increase.

  18. Influences of regional pollution and long range transport over Hyderabad using ozone data from MOZAIC

    NASA Astrophysics Data System (ADS)

    Srivastava, S.; Naja, M.; Thouret, V.

    2015-09-01

    Long-term (2005-2011) MOZAIC (Measurements of OZone and water vapor by Airbus In-Service air Craft) ozone data have been investigated over Hyderabad (17.37° N, 78.47°E, 489 m amsl), India using back-air trajectories and contribution from regional pollution and long-range transport are assessed. Ozone data are grouped and analysed according to the air-mass residence time over the central India, marine region and Africa/Middle East regions. Ozone shows a linear dependence on air-mass residence time over the central India region for about six days. Rate of ozone increase is maximum during summer (boundary layer 6.8 ± 0.9 ppbv/day, lower free troposphere 2.4 ± 0.4 ppbv/day) and minimum during winter (boundary layer 1.5 ± 0.2 ppbv/day, lower free troposphere 0.8 ± 0.7 ppbv/day). The background ozone is estimated by extrapolating the linear regression line to zeroth residence day and is found to be significantly lower during summer/monsoon (15.8 ± 2.4 ppbv) within the boundary layer due to influence of marine air-mass. Monthly variation of the boundary layer ozone shows a distinct peak during March-April months. Simultaneous investigation of fire counts and potential source contribution function analysis confirms that Indo-Gangetic Plain (IGP) outflow has a significant contribution in ozone enhancement over even at this southern region throughout the year except in summer-monsoon season. The ozone in regionally polluted air masses influenced by the central Indian region is found to be higher than average ozone by 6-15% within the boundary layer and by 5-9% in the lower troposphere during different seasons. The marine air shows a lower ozone level by 4-28 ppbv throughout the year within the boundary layer. Role of long-range transport from Africa/Middle East is found to be significant in the lower troposphere and shows 4.4 ppbv and 9 ppbv higher ozone mixing ratio during summer and autumn, respectively.