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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)

    Baltacı, H.; Kındap, 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. Influence of sea-land breezes on the tempospatial distribution of atmospheric aerosols over coastal region.

    PubMed

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

    2011-04-01

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

  3. Local and Regional Influences on Atmospheric Nutrient Deposition in Southeast Brazil

    NASA Astrophysics Data System (ADS)

    Allen, A. G.; Machado, C. M.; Cardoso, A. A.

    2009-05-01

    The objective of this work was to quantify sources of atmospheric nutrients, which are subsequently deposited to agricultural soils and natural ecosystems of São Paulo State (Brazil). The atmospheric concentrations of soluble ions (NO3-, NH4+, PO43-, SO42-, Cl-, K+, Na+, Mg2+ and Ca2+) in aerosol were evaluated, together with the gases NO2, NH3, HNO3 and SO2. Identification of nutrient sources was achieved using principal component analysis (PCA) followed by multiple linear regression analysis (MLRA). Dry deposition fluxes were estimated using the measured atmospheric concentrations together with dry deposition velocities of gases and aerosols to different surface types. Results showed that the main sources of nutrients to the regions atmosphere were fossil and biofuel combustion (N and S species), agricultural biomass burning (N, S, K and P), re-suspension of soils and dusts (Ca and Mg), and to a lesser extent long-range transport (S). NO2 concentrations were more influenced by local emissions and subsequent chemical transformations occurring on a scale of up to 200-300 km. HNO3 was much less spatially variable, with consistently higher concentrations during warmer, drier periods, indicating an agreement with gas phase/aerosol phase thermodynamic equilibrium theory. Scavenging of gaseous HNO3 was a source of nitrate, for which deposition fluxes were higher during the dry season, when significant relationships were obtained between nitrate concentrations and biomass burning intensity. Additional sources were indicated for particulate nitrate and sulphate, such as road transport and secondary reactions. During winter, the main source of gaseous ammonia was biomass burning, while emissions from soils and wastes predominated during summer. Modeled deposition fluxes were highest to tropical forest and lowest to water and pasture surfaces. In agricultural areas, the deposition fluxes of aerosol components N, P and K (0.37, 0.029 and 0.59 kg ha-1 yr-1, respectively) were equivalent to < 0.5 % of the amounts in fertilizer applied annually to plantations. Inclusion of gaseous dry deposition of nitrogen-containing compounds increased the total nitrogen flux by around 5 to 10-fold, depending on surface type.

  4. 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.

  5. Investigation of aerosol components influencing atmospheric transfer of UV radiation in Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Reinart, A.; Kikas, Ü.; Tamm, E.

    2006-01-01

    Linking of atmospheric aerosol size distributions and optical properties via predefined aerosol components was investigated. The measured aerosol volume distributions were decomposed to Optical Properties of Aerosols and Clouds (OPAC) components, and aerosol optical properties were calculated for a mixture of those components. The obtained aerosol optical properties were then used for modeling the surface UV irradiances with the libRadtran radiative transfer code. The results were verified with the columnar aerosol characteristics obtained from Aerosol Robotic Network (AERONET) station Tõravere (58.26°N, 26.46°E) and clear-sky surface UV measurements in Pärnu, Estonia (58.38°N, 24.51°E). The best decomposition results were obtained with four OPAC components, when their lookup characteristics varied within ±10%. Variation of aerosol optical properties in 17 days was influenced by the following aerosol components: soot, 1.2 ± 1.4%; insoluble, 23.1 ± 8.3%; water-soluble, 44.0 ± 10.8%; accumulation mode sea salt, 31.6 ± 6.2% of total aerosol volume. The average refractive index (for λ = 440 nm) of the component mixture was of 1.42 - 0.013i. Interpretation of the soot component was disputable, since similarly high soot concentrations corresponded to the secondary particles in polluted atmosphere and the nucleation bursts in clean atmosphere. The sea-salt component showed a correlation with the aerosol residence time over sea. The water-soluble component and the additional "biomass haze" component represented partly the same aerosol volume in the diameter range of 0.18-1.8 μm. The surface UV irradiances modeled with the AERONET data and the fitted aerosol components were highly correlated with each other, but both model results underestimated the UV extinction by aerosol.

  6. Influence of Atmospheric Solar Radiation Absorption on Photodestruction of Ions at D-Region Altitudes of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.

    2016-04-01

    The influence of atmospheric solar radiation absorption on the photodetachment, dissociative photodetachment, and photodissociation rate coefficients (photodestruction rate coefficients) of O-, Cl-, O2 -, O3 -, OH-, NO2 -, NO3 -, O4 -, OH-(H2O), CO3 -, CO4 -, ONOO-, HCO3 -, CO3 -(H2O), NO3 -(H2O), O2 +(H2O), O4 +, N4 +, NO+(H2O), NO+(H2O)2, H+(H2O) n for n = 2-4, NO+(N2), and NO+(CO2) at D-region altitudes of the ionosphere is studied. A numerical one-dimensional time-dependent neutral atmospheric composition model has been developed to estimate this influence. The model simulations are carried out for the geomagnetically quiet time period of 15 October 1998 at moderate solar activity over the Boulder ozonesonde. If the solar zenith angle is not more than 90° then the strongest influence of atmospheric solar radiation absorption on photodestruction of ions is found for photodissociation of CO4 - ions when CO3 - ions are formed. It follows from the calculations that decreases in the photodestruction rate coefficients of ions under consideration caused by this influence are less than 2 % at 70 km altitude and above this altitude if the solar zenith angle does not exceed 90°.

  7. Influence of Large-scale Climate Modes on Atmospheric Rivers That Drive Regional Precipitation Extremes

    NASA Astrophysics Data System (ADS)

    Guan, B.; Molotch, N. P.; Waliser, D. E.; Fetzer, E. J.; Neiman, P. J.

    2014-12-01

    Atmospheric rivers (ARs) are narrow channels of enhanced meridional water vapor transport between the tropics and extratropics that drive precipitation extremes in the west coast areas of North America and other continents. The influence of large-scale climate modes on ARs is analyzed in terms of modulation on AR frequency and AR-related snow water equivalent (SWE) anomalies, with a focus on understanding the causes of the anomalously snowy winter season of 2010/2011 in California's Sierra Nevada. Mean SWE on 1 April 2011 was ~70% above normal averaged over 100 snow sensors. AR occurrence was anomalously high during the season, with 20 AR dates from November to March and 14 dates in the month of December 2010, compared to the mean occurrence of 9 dates per season. Most of the season's ARs occurred during negative phases of the Arctic Oscillation (AO) and the Pacific-North American (PNA) teleconnection pattern. Analysis of all winter ARs in California during water years 1998-2011 indicates more ARs occur during the negative phase of AO and PNA, with the increase between positive and negative phases being ~90% for AO, and ~50% for PNA. The circulation pattern associated with concurrent negative phases of AO and PNA, characterized by cyclonic anomalies centered northwest of California, provides a favorable dynamical condition for ARs. The analysis suggests that the massive Sierra Nevada snowpack during the 2010/2011 winter season is primarily related to anomalously high frequency of ARs favored by the joint phasing of -AO and -PNA, and that a secondary contribution is from increased snow accumulation during these ARs favored by colder air temperatures associated with -AO, -PNA and La Niña. The results have implications for subseasonal-to-seasonal predictability of AR activities and related weather and water extremes.

  8. Influence of halophyte plantings in arid regions on local atmospheric structure

    NASA Astrophysics Data System (ADS)

    Pielke, R. A.; Lee, T. J.; Glenn, E. P.; Avissar, R.

    1993-06-01

    The practicality of modifying climate in arid regions through irrigation has up to now been constrained by the availability of fresh water with which to grow crops. The present results suggest a new paradigm: the use of salt water to grow halophyte crops and modify local climate along coastal deserts and other arid regions where saline water supplies are available.

  9. 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.

  10. Solar Terrestrial Influences on the D Region as Shown by the Level of Atmospheric Radio Noise

    NASA Technical Reports Server (NTRS)

    Satori, G.; Schaning, B.

    1984-01-01

    Measurements of the integrated atmospheric radio noise field strength at 27 kHz, used here, were made from 1965 to 1975 at Uppsala, Kuhlungsborn, and Prague-Panska Ves. The large scale meteorological situation was considered by comparing solar disturbed and undisturbed periods under similar weather situations. In order to show the effects of the precipitating high energy particle (HEP) flux and of the Forbush decrease on the noise level between pairs of stations were computed as deviations from the monthly median. Delta E (dB), day by day for all six periods was studied. The correlation coefficients for noon as well as for night values were computed. The correlation coefficients were compared with those for solar undisturbed periods.

  11. 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.

  12. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change: The MINK project

    SciTech Connect

    Rosenberg, N.J.; Crosson, P.R.

    1991-08-01

    This overview report explains the rationale for and the methodology used in conduct of the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project'' commissioned by the US Department of Energy. The MINK project includes four states -- Missouri, Iowa, Nebraska and Kansas. The major findings of the study are also presented in this overview, which accompanies a series of reports in which the requisite technical details on methodology, sectoral analyses and integrated analysis of climate change impacts and responses are provided in detail. The report topics in this analysis series of potential greenhouse effects are: (1) background and baseline; (2) agricultural production and resource use in the MINK region without and with climate change; (3) a farm-level simulation of the effects of climate change on crop productivity in the MINK region; (4) forest resources; (5) water resources; (6) energy; (7) consequences of climate change for the MINK economy: impacts and responses.

  13. Influence of airmass transport events on the variability of surface ozone at Xianggelila Regional Atmosphere Background Station, Southwest China

    NASA Astrophysics Data System (ADS)

    Ma, J.; Lin, W. L.; Zheng, X. D.; Xu, X. B.; Li, Z.; Yang, L. L.

    2014-01-01

    In situ measurements of ozone (O3), carbon monoxide (CO) and meteorological parameters were made from December 2007 to November 2009 at the Xianggelila Regional Atmosphere Background Station (28.006° N, 99.726° E, 3580 m a.s.l.), Southwest China. It is found that both O3 and CO peaked in spring while the valleys of O3 and CO occurred in summer and winter, respectively. A normalized indicator (marked as "Y") of transport events on the basis of the monthly normalized O3, CO, and water vapor, is proposed to evaluate the occurrence of O3 transport events from the upper, O3-rich atmosphere. This composite indicator has the advantage of being less influenced by and seasonal or occasional variations of individual factors. It is shown that the most frequent transport events occurred in winter and they can make a significant contribution to surface O3 at Xianggelila. A case of strong O3 transport event under the synoptic condition of a~deep westerly trough is studied by the combination of the Y indicator, potential vorticity, total column ozone, and trajectory analysis. A 9.6 ppb increase (21.0%) of surface ozone is estimated based on the impacts of deep transport events in winter. Asian Monsoon plays an important role in suppressing O3 accumulation in summer and fall.

  14. 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.

  15. 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 μm 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

  16. Influence of air mass downward transport on the variability of surface ozone at Xianggelila Regional Atmosphere Background Station, southwest China

    NASA Astrophysics Data System (ADS)

    Ma, J.; Lin, W. L.; Zheng, X. D.; Xu, X. B.; Li, Z.; Yang, L. L.

    2014-06-01

    In situ measurements of ozone (O3), carbon monoxide (CO) and meteorological parameters were made from December 2007 to November 2009 at the Xianggelila Regional Atmosphere Background Station (28.006° N, 99.726° E; 3580 m a.s.l.), southwest China. It was found that both O3 and CO peaked in spring while the minima of O3 and CO occurred in summer and winter, respectively. A normalized indicator (marked as "Y") on the basis of the monthly normalized O3, CO and water vapor, is proposed to evaluate the occurrence of O3 downward transport from the upper, O3-rich atmosphere. This composite indicator has the advantage of being less influenced by the seasonal or occasional variations of individual factors. It is shown that the most frequent and effective transport occurred in winter (accounting for 39% of the cases on the basis of a threshold of the Y value larger than 4) and they can make a significant contribution to surface O3 at Xianggelila. A 9.6 ppb increase (21.0%) of surface ozone is estimated based on the impact of deep downward transport events in winter. A case of strong O3 downward transport event under the synoptic condition of a deep westerly trough is studied by the combination of the Y indicator, potential vorticity, total column ozone and trajectory analysis. Asian monsoon plays an important role in suppressing O3 accumulation in summer and fall. The seasonal variation of O3 downward transport, as suggested by the Y indicator at Xianggelila, is consistent with the seasonality of stratosphere-to-troposphere transport and the subtropical jet stream over the Tibetan Plateau.

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

    SciTech Connect

    Fast, J.D.

    1994-09-30

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

  18. Influence of the orographic roughness of glacier valleys across the Transantarctic Mountains in an atmospheric regional model

    NASA Astrophysics Data System (ADS)

    Jourdain, Nicolas C.; Gallée, Hubert

    2011-03-01

    Glacier valleys across the Transantarctic Mountains are not properly taken into account in climate models, because of their coarse resolution. Nonetheless, glacier valleys control katabatic winds in this region, and the latter are thought to affect the climate of the Ross Sea sector, frsater formation to snow mass balance. The purpose of this paper is to investigate the role of the production of turbulent kinetic energy by the subgrid-scale orography in the Transantarctic Mountains using a 20-km atmospheric regional model. A classical orographic roughness length parametrization is modified to produce either smooth or rough valleys. A one-year simulation shows that katabatic winds in the Transantarctic Mountains are strongly improved using smooth valleys rather than rough valleys. Pressure and temperature fields are affected by the representation of the orographic roughness, specifically in the Transantarctic Mountains and over the Ross Ice Shelf. A smooth representation of escarpment regions shows better agreement with automatic weather station observations than a rough representation. This work stresses the need to improve the representation of subgrid-scale orography to simulate realistic katabatic flows. This paper also provides a way of improving surface winds in an atmospheric model without increasing its resolution.

  19. Possible influence of atmospheric circulations on winter haze pollution in the Beijing-Tianjin-Hebei region, northern China

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    Using the daily records derived from the synoptic weather stations and the NCEP/NCAR and ERA-Interim reanalysis data, the variability of the winter haze pollution (indicated by the mean visibility and number of hazy days) in the Beijing-Tianjin-Hebei (BTH) region during the period 1981 to 2015 and its relationship with the atmospheric circulations at middle-high latitude were analyzed in this study. The winter haze 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. In the raw (unfiltered) correlations, the correlation coefficients between the six indices and the winter visibility (number of hazy days) varied from 0.57 (0.47) to 0.76 (0.6) with an average of 0.65 (0.54); in the high-frequency ( < 10 years) correlations, the coefficients varied from 0.62 (0.58) to 0.8 (0.69) with an average of 0.69 (0.64). The six circulation indices together can explain 77.7 % (78.7 %) and 61.7 % (69.1 %) variances of the winter visibility and the number of hazy days in the year-to-year (inter-annual) variability, respectively. The increase in Ic (a comprehensive index derived from the six individual circulation indices) can cause a shallowing of the East Asian trough at the middle troposphere and a weakening of the Siberian high-pressure field at sea level, and is then accompanied by a reduction (increase) of horizontal advection and vertical convection (relative humidity) in the lowest troposphere and a reduced boundary layer height in BTH and its neighboring areas, which are favorable for the formation of haze pollution in BTH winter, and vice versa. The high level of the prediction statistics and the reasonable mechanism suggested that the winter haze pollution in BTH can be forecasted or estimated credibly based on the optimized atmospheric circulation indices. Thus it is helpful for government decision-making departments to take action in advance in dealing with probably severe haze pollution in BTH indicated by the atmospheric circulation conditions.

  20. 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.

  1. 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.

  2. Influence of atmospheric circulation patterns on the oxygen isotope ratio of tree rings in the Alpine region

    NASA Astrophysics Data System (ADS)

    Saurer, Matthias; Kress, Anne; Leuenberger, Markus; Rinne, Katja T.; Treydte, Kerstin S.; Siegwolf, Rolf T. W.

    2012-03-01

    The oxygen isotope ratio of precipitation and tree rings is a complex function of climate variables and atmospheric dynamics, which often makes the interpretation of δ18O for palaeoclimate research challenging. Here we analyzed monthly precipitation δ18O series for 1973-2004 and annually resolved tree ring δ18O chronologies for 1945-2004 for three sites in Switzerland: one north of the Alps, one at high-elevation within the Alps, and one south of the Alps. The goal of the study was to improve the understanding of the tree ring archive by a systematic analysis of nonlocal parameters related to atmospheric circulation, in particular, geopotential height field anomalies and the frequency of synoptic weather situations, in addition to the usual local climate parameters like temperature, sunshine duration, and relative humidity. We observed that on average high-pressure situations during summer were associated with relatively high δ18O and low-pressure situations were associated with relatively low δ18O, for both the isotope ratio in precipitation and tree rings. However, correlations to the frequency of weather types were not higher than simple correlations to local temperature. Accordingly, we constructed a combined index from temperature and air pressure that proved to be a good predictor of δ18O in precipitation and used this as the source water term in a tree ring isotope fractionation model. This enabled us to use the model beyond the period where isotope values for precipitation are available, opening new perspectives in the interpretation of long tree ring δ18O chronologies.

  3. Regional Limits to Sequestration of Atmospheric C in Soils: Influence of Soil C Fractions and Agricultural Practices

    NASA Astrophysics Data System (ADS)

    Conant, R. T.; Six, J.; Paustian, K.; Paul, E. A.

    2001-05-01

    Agricultural management has substantial effects on C output from soil, primarily through tillage, and on quantity and amount of C input to soil through residue management. The dynamics of agricultural management impacts are reasonably well understood and soil C responses are adequately predicted by a number of soil organic matter models in most systems. However, some data suggests that responses to increases in residue return do not always lead to increased soil C, as most models would predict; some soils appear to be saturated with respect to C. Therefore, models may over-predict the capacity of soils to stabilize soil C in some regions. Similarly, soil C levels may be near saturation in some systems and estimates of C sequestration potential in these systems may be too large. Conversely, soils in other regions are substantially below saturation level and could stabilize significant amounts of C in soils. The purpose of this presentation is to explore the implications of the concept of soil C saturation to identify areas (1) likely to be saturated with respect to soil C, (2) likely to become saturated with changes in agricultural management, and (3) areas far from saturation capable of stabilizing large amounts of C in soil. We compare output from a new model that explicitly accounts for limits to physical protection of soil organic matter with a more traditional soil organic matter model for a range of long-term agricultural research plots with different cultivation, rotation, and fertilization treatments. The result is a map of soils saturated with respect to C and of areas with soil C saturation deficits of varying magnitude.

  4. 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.

  5. Studying the influence of strong meteorological disturbances in the Earth's lower atmosphere on variations of ionospheric parameters in the Asian region of Russia

    NASA Astrophysics Data System (ADS)

    Chernigovskaya, Marina; Kurkin, Vladimir; Orlov, Igor; Oinats, Alexey; Sharkov, Eugenii

    2010-05-01

    Short-period temporal variations of ionospheric parameters were analyzed to study probabilities of manifestation of strong meteorological disturbances in the Earth's lower atmosphere in variations of upper atmosphere parameters in a zone far removed from a disturbance source. In the analysis, we used data on maximum observed frequencies (MOF) of oblique sounding (OS) signals along Norilsk-Irkutsk, Magadan-Irkutsk, and Khabarovsk-Irkutsk paths in East Siberia and the Far East. These data were obtained during solar minimum at equinoxes (March, September) in 2008-2009. Analyzing effects of wave disturbances in ionospheric parameters, we take into account helio-geomagnetic and meteorological conditions in regions under study to do an effective separation between disturbances associated with magnetospheric-ionospheric coupling and those induced by the influence of the lower atmosphere on the upper one. The frequency analysis we conducted revealed time intervals with higher intensity of short-period oscillations which may have been interpreted as manifestation of large-scale traveling ionospheric disturbances (TIDs) whose sources were internal gravity waves (IGWs) with periods of 1-5 hours. The complex analysis of helio-geomagnetic, ionospheric, and atmospheric data as well as data on tropical cyclones established that the detected TIDs were unrelated to helio-geomagnetic disturbances (2008-2009 exhibited solar minimum and quiet geomagnetic conditions). The analysis of other potential sources of the observed short-period wave disturbances shows that observed TIDs do not always coincide in time with passage of local meteorological fronts through the region of subionospheric points of OS paths and are not associated with passage of solar terminator. An attempt was made to connect a number of detected TIDs with ionospheric responses to tropical cyclones (TC) which were in active phase in the north-west of the Pacific Ocean during the periods considered. A considerable increase in energy of short-period wave disturbances was observed along Khabarovsk-Irkutsk, Magadan-Irkutsk, and Norilsk-Irkutsk paths during the active tropical cyclogenesis in September 2008-2009. Intensity of the observed TIDs decreased as midpoints of OS paths moved westward away from potential IGW sources. Ionospheric responses to wave disturbance propagation from the same IGW sources differ in the OS paths under analysis. This must be associated with different geometry of the OS paths as well as with the fact that the IGW source under consideration changes in intensity and its coordinates (stages and motion paths of tropical cyclones) during TC development. Thus there is an angular dependence between the wave disturbance propagation direction and the line connecting midpoints of the OS paths. Velocities of wave disturbance propagation (~90-170 m/s) were measured from the delay period of TIDs passage in regions of midpoints of spaced-apart OS paths. Short-period TIDs can also be observed at spring equinox in March 2008-2009 under quiet helio-geomagnetic conditions and in the absence of active tropical cyclones in the north-west of the Pacific Ocean, but TIDs energy is much lower than that in autumn. Authors note it was not possible to identify potential IGW sources for some TIDs within the scope of this work. These TIDs may be related to ionospheric responses to seasonal transitions in the upper atmosphere dynamic regime during the equinoxes under study. Further systematic investigations in this area of study are required to store statistics of observations of ionospheric responses to strong meteorological disturbances. The study was supported by the RFBR grant № 09-05-00760.

  6. Experimental evaluation of atmospheric aerosol turbidity in different Atlantic regions

    SciTech Connect

    Plakhina, I.N.; Pyrogov, S.M.

    1994-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

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

  8. Coarse-Resolution Daily Inundation Dynamics over the Alaska-Yukon Region: Comparison with High-Resolution Inundation Products and Influences from Atmospheric Drivers

    NASA Astrophysics Data System (ADS)

    Schroeder, R.; McDonald, K. C.; Rawlins, M. A.; Podest, E.; Whitcomb, J.; Mogahddam, M.; Zimmermann, R.

    2009-12-01

    Natural wetland complexes are a major source of atmospheric methane which is an important greenhouse gas. Wetland surface water variations and associated methane production are tightly linked and highly dependent on both climate and available plant material. Hence, characterizing the extent and distribution of wetlands is crucial in understanding the effect of climate change on wetlands dynamics, carbon and hydrological cycles, weather and biodiversity. This study presents a remote sensing technique for determining daily surface water fractions based on multiple satellite remote sensing data sets. The focus is on the Alaska-Yukon region and daily inundation dynamics for the period from 2002 until 2008. Our inundation detection approach employs passive microwave data from AMSR-E on NASA’s Earth Observing System (EOS) Aqua satellite and Leaf Area Index (LAI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the EOS Terra satellite. Radar backscatter from SeaWinds-on-QuikSCAT (QSCAT) is used to maximize the sensitivity to the presence of vegetation biomass in inundated areas. A comparison with high-resolution maps of open water and wetlands vegetation, derived from JERS SAR, and open water area, derived from LANDSAT, suggests that this mapping approach shows great potential for accurate mapping of inundation dynamics across this region. Variations in open water area as seen by LANDSAT and SAR imagery are detected, as well as the sensitivity to variations in inundated vegetation. We note reasonable agreement between surface inundation fraction, river discharge, and simulated river runoff simulated by a hydrological model, with pronounced interannual variations that could be explained by year-to-year changes in large-scale atmospheric circulation over Alaska. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA).

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

    SciTech Connect

    Rosenberg, N.J.; Crosson, P.R.

    1991-08-01

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

  10. Moon influence on equatorial atmospheric angular momentum

    NASA Astrophysics Data System (ADS)

    Bizouard, Christian; Zotov, Leonid; Sidorenkov, Nikolay

    2014-05-01

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

  11. 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.

  12. 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.

  13. Solar wind influence on atmospheric processes in winter Antarctica

    NASA Astrophysics Data System (ADS)

    Troshichev, Oleg; Egorova, Larisa; Vovk, Valery; Janzhura, Alexander

    The experimental results demonstrate influence of the great southward interplanetary magnetic field (IMF) and the corresponding geoeffective interplanetary electric field on atmospheric pro-cesses in the central Antarctica, where the large-scale system of vertical circulation takes place during the winter seasons. The interplanetary electric field influence is realized through ac-celeration of the air masses, descending into the lower atmosphere from the troposphere, and formation of cloudiness above the Antarctic Ridge, where the descending air masses enter the surface layer. The cloudiness results in the sudden warmings in the surface atmosphere, because the cloud layer efficiently backscatters the long wavelength radiation going from ice sheet, but does not affect the process of adiabatic warming of the descending air masses. Influence of the interplanetary electric field on cloudiness has been revealed for epochs of the solar activity minimum, when Forbush decreases effect is absent. The altitudinal profiles of temperature, varying in the opposite manner under influence of the southward and northward IMF, indicate that the cloud layer formation occurs at h = 8 -10 km. The acceleration of the descending air masses is followed by a sharp increase of the atmospheric pressure in the near-pole region, which gives rise to the katabatic wind strengthening above the entire Antarctica. As a result, the circumpolar vortex around the periphery of the Antarctic continent decays and the surface easterlies, typical of the coast stations during the winter season, are replaced by southerlies. It is suggested that the resulting invasion of the cold air masses into the Southern ocean leads to destruction the regular relationships between the sea level pressure fluctuations in the South-east Pacific high and the North Australian-Indonesian low, since development the El-Niño event n strongly follows anomalous atmospheric processes in the winter Antarctica.

  14. 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 μmol/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 μmol/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.

  15. [Regional atmospheric environment risk source identification and assessment].

    PubMed

    Zhang, Xiao-Chun; Chen, Wei-Ping; Ma, Chun; Zhan, Shui-Fen; Jiao, Wen-Tao

    2012-12-01

    Identification and assessment for atmospheric environment risk source plays an important role in regional atmospheric risk assessment and regional atmospheric pollution prevention and control. The likelihood exposure and consequence assessment method (LEC method) and the Delphi method were employed to build a fast and effective method for identification and assessment of regional atmospheric environment risk sources. This method was applied to the case study of a large coal transportation port in North China. The assessment results showed that the risk characteristics and the harm degree of regional atmospheric environment risk source were in line with the actual situation. Fast and effective identification and assessment of risk source has laid an important foundation for the regional atmospheric environmental risk assessment and regional atmospheric pollution prevention and control. PMID:23379138

  16. Wet and Dry Regions in Jupiter's Atmosphere

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  17. Region effects influence local tree species diversity.

    PubMed

    Ricklefs, Robert E; He, Fangliang

    2016-01-19

    Global patterns of biodiversity reflect both regional and local processes, but the relative importance of local ecological limits to species coexistence, as influenced by the physical environment, in contrast to regional processes including species production, dispersal, and extinction, is poorly understood. Failure to distinguish regional influences from local effects has been due, in part, to sampling limitations at small scales, environmental heterogeneity within local or regional samples, and incomplete geographic sampling of species. Here, we use a global dataset comprising 47 forest plots to demonstrate significant region effects on diversity, beyond the influence of local climate, which together explain more than 92% of the global variation in local forest tree species richness. Significant region effects imply that large-scale processes shaping the regional diversity of forest trees exert influence down to the local scale, where they interact with local processes to determine the number of coexisting species. PMID:26733680

  18. Studies of influence of energy distribution on the upper atmosphere

    NASA Astrophysics Data System (ADS)

    Sheng, Cheng

    The energy inputs into the upper atmosphere including both solar irradiation and geomagnetic energy can significantly change the upper atmosphere such as the neutral and plasma densities, velocities and temperatures. Therefore, the precise specification of the energy inputs is critical to estimate the ionosphere/thermosphere variation during both quiet and storm times. In order to improve the understanding of the energy distribution and its influence at high latitudes, specifically, we have conducted the following studies. (1) Estimation of the altitudinal distribution of Joule heating from COSMIC observations. Joule heating is the most significant way to dissipate geomagnetic energy at high latitudes. But the altitudinal distribution of Joule heating has not been studied in detail. Based on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations from 2008 to 2011, the height-integrated Pedersen conductivities in both E (100-150 km) and F (150-600 km) regions and their ratio lambdaP (sumPE/sumPF) have been calculated. The result from data analysis (˜5.5) shows a smaller value than that from model (˜9), which indicates that the energy inputs into the F region may be underestimated in the model. Dependences of the ratio and the conductance in both E and F regions on the solar and geomagnetic activities have been studied as well. (2) The influence of cusp energy on the thermospheric winds has also been studied, through simulating a real event. The Global Ionosphere Thermosphere Model (GITM) has been run in different cases and under different resolutions to investigate the neutral dynamics around the cusp region. The results indicate that the heating added in the cusp causes the change of pressure gradient around the cusp and changes the neutral wind dynamics there. (3) Correlation of Poynting flux and soft particle precipitation in the dayside polar cap boundary regions has been investigated using DMSP satellite measurements. The signatures of enhanced electromagnetic (Poynting flux) and kinetic (soft electron precipitation) energy deposition in the polar cap boundary regions have been observed previously. But it is not clear how those two different kinds of energy inputs are correlated with each other, which can cause significant difference on the ionosphere/thermosphere response. Our analysis shows that the two energy sources are coincident in some cases, but a clear displacement can also be identified in others, depending on the location and condition. The consequence of the energy displacement has been simulated in the GITM model. These studies will help us get a more comprehensive understanding of how the energy is deposited in the high-latitude upper atmosphere, and how the ionosphere-thermosphere system responds to different energy distributions.

  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. Atmospheric modes influence on Iberian Poleward Current variability

    NASA Astrophysics Data System (ADS)

    deCastro, M.; Gómez-Gesteira, M.; Álvarez, I.; Crespo, A. J. C.

    2011-04-01

    The inter-annual variability of the Iberian Poleward Current (IPC) along the northwestern coast of the Iberian Peninsula (IP) (40-43°N) and its intrusion in the Cantabrian Sea (Navidad, 6-8°W) were analyzed in terms of the atmospheric forcing. The January Sea Surface Temperature (J SST) was obtained from the advanced very high resolution radiometer (AVHRR) NOAA satellite from 1985 to 2006. It is a well documented fact that the existence of a tongue of water warmer than the surrounding ones (IPC) which circulates along the western Iberian shelf edge, turn eastward around Cape Finisterre, and enters in the Cantabrian Sea generating Navidad at the beginning of every winter. However, in the present study it has been highlighted that there are several years (1986, 1987, 1992, 1997, 1999, 2004 and 2005) during which water from coast to the adjacent shelf is much colder than the oceanic one remarking a weak or inexistent IPC during these Januaries. In addition, the dependence of SST on the most representative regional patterns with some influence upon the eastern North Atlantic region was analyzed by means of correlations between November-December atmospheric modes and J SST. The considered modes were: North Atlantic Oscillation pattern (NAO), Eastern Atlantic pattern (EA), Eastern Atlantic Western Russia pattern (EA/WR), Polar/Eurasia pattern (POL) and Scandinavia pattern (SCA). This analysis reveals that two atmospheric patterns (N-D NAO and N-D EA/WR) are responsible of the main variability of the J SST of the western and northern IP. J SST is negatively correlated with N-D NAO and positively correlated with N-D EA/WR. Multivariate analysis involving both modes provides correlation coefficients on the order of 0.7 on both coasts (western and northern). The influence of both modes on J SST was observed to be on the same order of magnitude but with different sign. These correlations were physically interpreted by means of an analysis of extreme events and Sea Level Pressure (SLP) composite analysis.

  1. Regional atmospheric composition modeling with CHIMERE

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  2. 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.

  3. 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.

  4. 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...

  5. 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 ...

  6. Io's surface - Its phase composition and influence on Io's atmosphere and Jupiter's magnetosphere

    NASA Technical Reports Server (NTRS)

    Fanale, F. P.; Banerdt, W. B.; Elson, L. S.; Johnson, T. V.; Zurek, R. W.

    1982-01-01

    The evidence and interpretations pertaining to the surface phase composition of Io and the mechanisms by which Io's surface influences its atmosphere are discussed. The mechanism by which Io's surface and/or atmosphere supplies neutral and ionic species to the region around the satellite and ultimately to the Jovian magnetosphere is also discussed. A model is suggested in which the global SO2 gas abundance is primarily controlled by buffering in the brightest, coldest regions. The net SO2 flux across the disk is limited by regional cold trapping on high albedo regions and possibly by the resistance of a tenuous non-SO2 residual atmosphere. The continuing migration of SO2 toward cooler regions and those lacking SO2 sources is opposed by SO2 destruction and planetary ejection processes, including sputtering, thus preventing buildup of thick, ubiquitous SO2 coverage.

  7. Influences of Atmospheric Stability State on Wind Turbine Aerodynamic Loadings

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  8. 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).

  9. Investigating causes of regional variations in atmospheric carbon dioxide concentrations

    NASA Astrophysics Data System (ADS)

    Corbin, Katherine D.

    Atmospheric CO2 concentrations are rapidly increasing due to anthropogenic activities; however, only about half of the emissions have accumulated in the atmosphere, and the fate of the remaining half remains uncertain. Since atmospheric CO2 concentrations contain information regarding carbon sources and sinks, it is important to understand CO 2 variability. This study investigated causes of atmospheric CO 2 variability, focusing on the relationship between CO2 concentrations and clouds, the impact of heterogeneous land cover and agricultural production, and the effect of redistributing fossil fuel emissions. Due to global coverage and sheer data volume, satellite CO2 concentrations will be used in inverse models to improve carbon source and sink estimates. Satellite concentrations will only retrieve CO2 measurements in clear conditions, and it is important to understand how CO 2 concentrations vary with cloud cover in order to optimally utilize these data. This study evaluated differences between clear-sky and mean concentrations on local, regional, and global scales. Analyses of in situ data, regional model simulations, and global model output all revealed clear-sky differences that were regionally coherent on sub-continental scales and that varied both with time and location. In the mid-latitudes, clear-sky CO2 concentrations were systematically lower than on average, and these differences were not due to biology, but rather to frontal convergence of large-scale gradients that were covered by clouds. Instead of using satellite data to represent temporal averages, inverse models and data assimilation systems that use satellite data to calculate carbon sources and sinks must be sampled consistently with the observations, including precise modeling of winds, clouds, fronts, and frontal timing. Just as CO2 concentrations vary with cloud cover, variability in atmospheric CO2 concentrations is also caused by heterogeneity in land cover and surface fluxes. This study focused on the impacts of land-cover heterogeneity and the effects of agricultural production on regional variations of atmospheric CO2 concentrations. Including sub-grid scale land cover heterogeneity improved simulated atmospheric CO2 concentrations by ˜ 1 ppm. Implementing a crop-phenology model that explicitly simulated corn and soybeans into a coupled ecosystem-atmosphere model dramatically improved CO2 fluxes and concentrations over the mid-continent, with reductions in CO2 concentration root mean square errors of nearly 50% (over 10 ppm at some locations). Both the model and observations showed concentrations as low as 340 ppm over central Iowa, and a regional gradient of over 30 ppm in ˜ 200 km occurred due to a combination of fluxes and meteorology. Since corn and soybeans have such a significant impact on both carbon fluxes and atmospheric concentrations, it is essential to model these crops accurately. In addition to biological surface fluxes, surface emissions due to fossil fuel combustion also cause variability in regional atmospheric CO2 concentrations. Using high-resolution fossil fuel emissions caused differences of over 10 ppm near the surface; and including temporal variability in the emissions impacted regional CO2 concentrations on monthly timescales, causing seasonal differences of more than 20 ppm in some locations. Using coarse spatial distributions and unaccounting for temporal variability in fossil fuel emissions created biases in the atmospheric CO2 concentrations and thus may cause significant errors in source and sink estimates from atmospheric inversions.

  10. Influence of atmospheric aerosols and desert reflectance properties on satellite radiance measurements

    NASA Technical Reports Server (NTRS)

    Bowker, D. E.; Davis, R. E.

    1992-01-01

    The influence of surface bidirectional reflectance factors, including shadowing, and of atmospheric aerosol variability are modeled for their effects on the remote sensing of desert targets from space in the 0.7-micron region at high spatial resolution. The white sand reflectance data of Salomonson (1968) are used as the basis for the simulation. The effects of the surface bi-directional reflectance and atmospheric aerosol on the nadir-normalized reflectance measured at the satellite are discussed individually and jointly. The net influence of these two factors is shown to depend on the magnitude of other parameters, such as the surface reflectance and solar zenith angle.

  11. Geomagnetic Activity Influence on Thermobaric Characteristics of the Atmosphere.

    NASA Astrophysics Data System (ADS)

    Rubtsova, O. A.; Zherebtsov, G. A.; Kovalenko, V. A.; Molodykh, S. I.

    2009-10-01

    The main points of the model of the solar activity effect on the Earth climatic system are presented. The model is based on the physical mechanism of heliogeophysical factors influence on climatic characteristics and atmospheric circulation in the high-latitude troposphere through the atmospheric electricity. In accordance with this mechanism, the atmospheric electricity parameters in the high latitudes depend on the solar activity; at the same time, they influence the altitude distribution of charged condensation nuclei in the troposphere, as well as the cloudiness formation and radiation balance. The mechanism is proved to operate more efficiently in the high latitudes resulting in additional cloudiness formation in areas with adequate vapour concentration. We present complex analysis results of response of temperature and tropospheric pressure fields to different heliogeophysical disturbances. It is detected that regular changes of the temperature and pressure field dynamic accompany these disturbances.

  12. 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.

  13. 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.

  14. Land-Atmosphere Coupling at Local, Regional, and Global Scales

    NASA Astrophysics Data System (ADS)

    Peters-Lidard, C. D.; Tao, W.; Santanello, J. A.; Kumar, S. V.; Shen, B.; Alonge, C.; Chern, J.

    2008-05-01

    Recent studies have examined aspects of land-atmosphere coupling, including the impacts of soil moisture and vegetation on the structure of the atmospheric boundary layer and initiation and evolution of clouds. However, due to limits in computational resources and/or theoretical knowledge, many of these studies have utilized highly parameterized representations of these components so that the true nature of land-atmosphere coupling is still unknown. In this NASA-NEWS-funded project, the NASA/GSFC Land Information System (LIS; http://lis.gsfc.nasa.gov) is used as the foundation for studying land-atmosphere coupling at local, regional and global scales through coupled simulations with the Weather Research and Forecasting (WRF; http://www.wrfmodel.org) model, and the GSFC Multi-Scale Modeling Framework (MMF). In this talk, we will present results from various coupled case studies indicating a strong sensitivity of the water and energy cycles to several controls, including soil moisture, vegetation, and the atmospheric boundary layer. We will also present results demonstrating the impact of the boundary layer and microphysical parameterizations on the diurnal cycles of water and energy fluxes, clouds, and precipitation.

  15. Arctic Storms in a Regionally Refined Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Roesler, E. L.; Taylor, M.; Boslough, M.; Sullivan, S.

    2014-12-01

    Regional refinement in an atmospheric general circulation model is a new tool in atmospheric modeling. A regional high-resolution solution can be obtained without the computational cost of running a global high-resolution simulation as global climate models have increasing ability to resolve smaller spatial scales. Previous work has shown high-resolution simulations, i.e. 1/8 degree, and variable resolution utilities have resolved more fine-scale structure and mesoscale storms in the atmosphere than their low-resolution counterparts. We will describe an experiment designed to identify and study Arctic storms at two model resolutions. We used the Community Atmosphere Model, version 5, with the Spectral Element dynamical core at 1/8-degree and 1 degree horizontal resolutions to simulate the climatological year of 1850. Storms were detected using a low-pressure minima and vorticity maxima - finding algorithm. It was found the high-resolution 1/8-degree simulation had more storms in the Northern Hemisphere than the low-resolution 1-degree simulation. A variable resolution simulation with a global low resolution of 1-degree and a high-resolution refined region of 1/8 degree over a region in the Arctic is planned. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND NO. 2014-16460A

  16. 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.

  17. The Middle Atmospheric variability over Indian region during Tropical cyclone

    NASA Astrophysics Data System (ADS)

    Bhagavathiammal, G. J.

    In order to study the various characteristics of atmosphere during the passage of tropical cyclones, some atmospheric parameters over Indian region has been studied. The tropospheric variability has been studied with the help of surface pressure variation obtained from microbarograph at Tirunelveli (8.7oN, 77.8oE). The stratospheric ozone variability has been obtained from the TOMS (Total Ozone Mapping Spectrometer) satellite over the Bay of Bengal as well as Arabian Ocean. The ionospheric current over Indian region has been obtained from the network of Indian Institute of Geomagnetism. We have studied the ionospheric current variations over Tirunelveli (inside the electrojet region) and Alibag (outside the electrojet region). The tropospheric cyclone track has been obtained from the Indian Meteorological Department. The pressure variation obtained over Tirunelveli has been converted into FFT spectrum and it shows the enhancement in power of surface gravity waves of period about 150 min. The magnitude of enhancement depends upon the distance of the cyclone track. The stratospheric ozone obtained by TOMS shows an increase in ozone during tropical depression by about 10 DU followed by decrease in total ozone up to 25 DU along the cyclone track. The ionospheric current shows the changes in power of Inertial Gravity Waves (IGW) over Tirunelveli as well as Alibag. The power of IGW over Tirunelveli shows decrease by about 25

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Characteristics of atmospheric CO2 and CH4 at the Shangdianzi regional background station in China

    NASA Astrophysics Data System (ADS)

    Fang, Shuang-xi; Tans, Pieter P.; Dong, Fan; Zhou, Huaigang; Luan, Tian

    2016-04-01

    Atmospheric CO2 and CH4 have been continuously measured at the Shangdianzi regional background station (SDZ) in China from 2009 to 2013. Based on the influences of local surface wind and long-distance transport, the observed records were flagged into locally influenced, Beijing-Tianjin-Hebei (BTH) influenced, and Russia, Mongolia, and Inner Mongolia autonomous region influenced (RMI). ∼ 81.4% of CO2 and ∼75.6% of CH4 mole fractions were flagged as locally representative, indicating that the atmospheric CO2 and CH4 at SDZ were strongly influenced by local sources and sinks. Cluster analysis of back trajectories proved that the atmospheric CO2 and CH4 were influenced by air masses from northwest (RMI) or from south and southeast (BTH). The CO2 and CH4 mole fractions in BTH are always higher than in RMI, with the largest difference of 11.5 ± 0.3 ppm for CO2 and 102 ± 1 ppb for CH4 in July. The annual growth rates of CO2 and CH4 in BTH are 3.8 ± 0.01 ppm yr-1 and 10 ± 0.1 ppb yr-1, respectively, which are apparently higher than those of the RMI and the global means. The long-term trends of CO2 and CH4 in BTH are deviating from those in RMI, with ratios of ∼1.0 ppm yr-1 for CO2 and ∼2 ppb yr-1 for CH4, indicating the strengths of CO2 and CH4 emission in Beijing-Tianjin-Hebei plain increased more than 20% every year.

  3. 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.

  4. Extensive regional atmospheric hydrocarbon pollution in the southwestern United States.

    PubMed

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

    2003-10-14

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

  5. Synergies Between Grace and Regional Atmospheric Modeling Efforts

    NASA Astrophysics Data System (ADS)

    Kusche, J.; Springer, A.; Ohlwein, C.; Hartung, K.; Longuevergne, L.; Kollet, S. J.; Keune, J.; Dobslaw, H.; Forootan, E.; Eicker, A.

    2014-12-01

    In the meteorological community, efforts converge towards implementation of high-resolution (< 12km) data-assimilating regional climate modelling/monitoring systems based on numerical weather prediction (NWP) cores. This is driven by requirements of improving process understanding, better representation of land surface interactions, atmospheric convection, orographic effects, and better forecasting on shorter timescales. This is relevant for the GRACE community since (1) these models may provide improved atmospheric mass separation / de-aliasing and smaller topography-induced errors, compared to global (ECMWF-Op, ERA-Interim) data, (2) they inherit high temporal resolution from NWP models, (3) parallel efforts towards improving the land surface component and coupling groundwater models; this may provide realistic hydrological mass estimates with sub-diurnal resolution, (4) parallel efforts towards re-analyses, with the aim of providing consistent time series. (5) On the other hand, GRACE can help validating models and aids in the identification of processes needing improvement. A coupled atmosphere - land surface - groundwater modelling system is currently being implemented for the European CORDEX region at 12.5 km resolution, based on the TerrSysMP platform (COSMO-EU NWP, CLM land surface and ParFlow groundwater models). We report results from Springer et al. (J. Hydromet., accept.) on validating the water cycle in COSMO-EU using GRACE and precipitation, evapotranspiration and runoff data; confirming that the model does favorably at representing observations. We show that after GRACE-derived bias correction, basin-average hydrological conditions prior to 2002 can be reconstructed better than before. Next, comparing GRACE with CLM forced by EURO-CORDEX simulations allows identifying processes needing improvement in the model. Finally, we compare COSMO-EU atmospheric pressure, a proxy for mass corrections in satellite gravimetry, with ERA-Interim over Europe at timescales shorter/longer than 1 month, and spatial scales below/above ERA resolution. We find differences between regional and global model more pronounced at high frequencies, with magnitude at sub-grid scale and larger scale corresponding to 1-3 hPa (1-3 cm EWH); relevant for the assessment of post-GRACE concepts.

  6. Deriving emissions on regional to global scales from atmospheric observations

    NASA Astrophysics Data System (ADS)

    Montzka, S. A.; Miller, B. R.; Siso, C.; Sweeney, C.; Andrews, A. E.; Miller, J. B.; Fischer, M. L.; Wang, H.

    2011-12-01

    Trace-gas observations can provide information about emissions on both global and regional spatial scales. Reliable 'top-down' global estimates are possible for a trace gas when its global mean atmospheric concentration and rate of change can be derived from atmospheric observations, provided loss rates are known. Global emission rates for long-lived ozone-depleting gases and substitute chemicals (e.g., HCFCs and HFCs) have been derived in this way with a range in different modeling approaches. The first part of this talk will discuss this method, its limitations, and the consistency of these emissions with estimates derived from inventories. The second half of the presentation will focus on deriving U.S. emissions of ozone-depleting and greenhouse gases from air samples regularly collected across the continental U.S. Mixing ratio enhancements provide information about recent emissions. A number of techniques have been used to assess both absolute and relative emission magnitudes of ozone-depleting and greenhouse gases from the continental U.S. over multi-annual periods. The extensive nature of the ongoing sampling program has allowed us to identify that emissions of some chemicals vary with season and by region. These results reaffirm that a fairly comprehensive sampling network is required to derive unbiased, top-down emission estimates for such trace gases.

  7. Influence of Galactic Cosmic Rays on atmospheric composition and dynamics

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    This study investigates the influence of the Galactic Cosmic Rays (GCRs) on the atmospheric composition, temperature and dynamics by means of the 3-D Chemistry Climate Model (CCM) SOCOL v2.0. Ionization rates were parameterized according to CRAC:CRII (Cosmic Ray induced Cascade: Application for Cosmic Ray Induced Ionization), a detailed state-of-the-art model describing the effects of GCRs in the entire altitude range of the CCM from 0-80 km. We find statistically significant effects of GCRs on tropospheric and stratospheric NOx, HOx, ozone, temperature and zonal wind, whereas NOx, HOx and ozone are annually averaged and the temperature and the zonal wind are monthly averaged. In the Southern Hemisphere, the model suggests the GCR-induced NOx increase to exceed 10 % in the tropopause region (peaking with 20 % at the pole), whereas HOx is showing a decrease of about 3 % caused by enhanced conversion into HNO3. As a consequence, ozone is increasing by up to 3 % in the relatively unpolluted southern troposphere, where its production is sensitive to additional NOx from GCRs. Conversely, in the northern polar lower stratosphere, GCRs are found to decrease O3 by up to 3 %, caused by the additional heterogeneous chlorine activation via ClONO2 + HCl following GCR-induced production of ClONO2. There is an apparent GCR-induced acceleration of the zonal wind of up to 5 m s-1 in the Northern Hemisphere below 40 km in February, and a deceleration at higher altitudes with peak values of 3 m s-1 around 70 km altitude. The model also indentifies GCR-induced changes in the surface air, with warming in the eastern part of Europe and in Russia (up to 2.25 K for March values) and cooling in Siberia and Greenland (by almost 2 K). We show that these surface temperature changes develop even when the GCR-induced ionization is taken into account only above 18 km, suggesting that the stratospherically driven strengthening of the polar night jet extends all the way down to the Earth's surface.

  8. Influence of galactic cosmic rays on atmospheric composition and temperature

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

    This study investigates the influence of the galactic cosmic rays (GCRs) on the atmospheric composition, temperature and dynamics by means of the 3-D Chemistry Climate Model (CCM) SOCOL v2.0. Ionization rates were parameterized according to CRAC:CRII (Cosmic Ray induced Cascade: Application for Cosmic Ray Induced Ionization), a detailed state-of-the-art model describing the effects of GCRs in the entire altitude range of the CCM from 0-80 km. We find statistically significant effects of GCRs on tropospheric and stratospheric NOx, HOx, ozone, temperature and zonal wind, whereas NOx, HOx and ozone are annually averaged and the temperature and the zonal wind are monthly averaged. In the Southern Hemisphere, the model suggests the GCR-induced NOx increase to exceed 10% in the tropopause region (peaking with 20% at the pole), whereas HOx is showing a decrease of about 3% caused by enhanced conversion into HNO3. As a consequence, ozone is increasing by up to 3% in the relatively unpolluted southern troposphere, where its production is sensitive to additional NOx from GCRs. Conversely, in the northern polar lower stratosphere, GCRs are found to decrease O3 by up to 3%, caused by the additional heterogeneous chlorine activation via ClONO2+HCl following GCR-induced production of ClONO2. There is an apparent GCR-induced acceleration of the zonal wind of up to 5 m/s in the Northern Hemisphere below 40 km in February, and a deceleration at higher altitudes with peak values of 3 m/s around 70 km altitude. The model also indentifies GCR-induced changes in the surface air, with warming in the eastern part of Europe and in Russia (up to 2.25 K for March values) and cooling in Siberia and Greenland (by almost 2 K). We show that these surface temperature changes develop even when the GCR-induced ionization is taken into account only above 18 km, suggesting that the stratospherically driven strengthening of the polar night jet extends all the way down to the Earth's surface.

  9. Factors influencing atmospheric composition over subarctic North America during summer

    NASA Technical Reports Server (NTRS)

    Wofsy, Steven C.; Fan, S. -M.; Blake, D. R.; Bradshaw, J. D.; Sandholm, S. T.; Singh, H. B.; Sachse, G. W.; Harriss, R. C.

    1994-01-01

    Elevated concentrations of hydrocarbons, CO, and nitrogen oxides were observed in extensive haze layers over northeastern Canada in the summer of 1990, during ABLE 3B. Halocarbon concentrations remained near background in most layers, indicating a source from biomass wildfires. Elevated concentrations of C2Cl4 provided a sensitive indicator for pollution from urban/industrial sources. Detailed analysis of regional budgets for CO and hydrocarbons indicates that biomass fires accounted for approximately equal to 70% of the input to the subarctic for most hydrocarbons and for acetone and more than 50% for CO. Regional sources for many species (including CO) exceeded chemical sinks during summer, and the boreal region provided a net source to midlatitudes. Interannual variations and long-term trends in atmospheric composition are sensitive to climatic change; a shift to warmer, drier conditions could increase the areas burned and thus the sources of many trace gases.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  11. 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.

  12. Influence of atmospheric turbulence on planetary transceiver laser ranging

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  13. 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 μg/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 μg/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.

  14. Surface Roughness Variations control the Regional Atmospheric Response to Contemporary Deforestation in Rondnia, Brazil

    NASA Astrophysics Data System (ADS)

    Khanna, J.; Medvigy, D.

    2014-12-01

    The net atmospheric response to deforestation is known to be a combination of individual atmospheric processes and their interactions triggered by changes in various land surface characteristics. These individual responses also vary with the scale of deforestation. Previous studies of atmospheric impacts of Amazonian deforestation have focused on very small (~1 km) and very large (hundreds of km) scales of deforestation and have showed that different land surface properties can dominate the atmospheric response at different scales. However, analysis of the net atmospheric impact of intermediate-scale deforestation (tens of km) has received less attention, despite it being a better representative of the contemporary landscape in some parts of the Amazon. This study looks at the effects of contemporary intermediate-scale deforestation in Rondnia, Brazil, with an emphasis on the role of changes in surface roughness, using a variable-resolution GCM, the Ocean-Land-Atmosphere Model. It is found that reductions in surface roughness give rise to a mesoscale circulation that is capable of convective triggering but that weakens the turbulent energy fluxes between land and atmosphere. Overall, this mesoscale circulation causes distinct impacts on the hydroclimates of the western and eastern halves of Rondnia, increasing convection in the former while suppressing it in the latter. These results show that the regional atmospheric response to contemporary intermediate-scale deforestation in Rondnia 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 which is the dominant factor at small scales of deforestation.

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

    SciTech Connect

    Bakwin, P.S.

    1989-01-01

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

  16. Simulation of fog influence on laser beam distribution in atmosphere

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  17. 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.

  18. 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.

  19. Atmospheric aerosol layers over Bangkok Metropolitan Region from CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Bridhikitti, Arika

    2013-06-01

    Previous studies suggested that aerosol optical depth (AOD) from the Earth Observing System satellite retrievals could be used for inference of ground-level air quality in various locations. This application may be appropriate if pollution in elevated atmospheric layers is insignificant. This study investigated the significance of elevated air pollution layers over the Bangkok Metropolitan Region (BMR) from all available aerosol layer scenes taken from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) for years 2007 to 2011. The results show that biomass burning smoke layers alone were the most frequently observed. The smoke layers accounted for high AOD variations and increased AOD levels. In the dry seasons, the smoke layers alone with high AOD levels were likely brought to the BMR via northeasterly to easterly prevailing winds and found at altitudes above the typical BMR mixing heights of approximately 0.7 to 1.5 km. The smoke should be attributed to biomass burning emissions outside the BMR.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. What can Venus and Mars tell us about Sun's direct influence on Earth's Atmosphere?

    NASA Astrophysics Data System (ADS)

    Lundin, R.

    2010-09-01

    Venus and Mars, Earth's sister planets, are similar but also very different compared to the Earth. The mass-density and surface properties bear certain commonality, but the atmospheric composition, the temperature and the surface pressure on Venus and Mars are very different compared to the Earth. Venus and Mars are arid planets with atmospheres dominated by a greenhouse gas CO2 (>95%), while the Earth's atmosphere is dominated by molecular Nitrogen and Oxygen. The main greenhouse gas in the Earth's atmosphere is water, with a minor contribution of CO2. Bearing these differences in mind, what can we possibly learn from Mars and Venus about the solar influence on the Earth's atmosphere? The answer can be found in how solar forcing affects a planetary atmosphere, more specifically the impact of solar EUV and solar wind variability on a planetary atmosphere. The lack of a strong intrinsic magnetic field on Mars and Venus means that solar wind forcing has a global effect on the upper atmosphere of Mars and Venus. Conversely, the Earth's intrinsic dipole magnetic field alleviates the forcing to narrow zones near the magnetic poles. Results obtained from Venus and Mars orbiters imply that solar wind forcing leads to a long-term gradual removal of atmospheric constituents. New information from ESAs Mars Express and Venus Express orbiters suggests short-term solar wind forcing effects as well, especially in the polar region. While the impact of solar forcing on the "unprotected" planets Venus and Mars seems conceivable, one might argue that similar forcing effects are unlikely on a magnetically protected planet. Short-term "space weather" effects on the Earth's tropospheric circulatory system have been reported in the past, but the effects have usually been discarded using arguments that such a weak forcing is unlikely to have any implications whatsoever on the Earth's weather system. However, considering the forcing observed in e.g. the Venus polar region, solar forcing may have a significant effect on the Earth's polar region upper atmosphere as well.

  5. 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.

  6. Extensive regional atmospheric hydrocarbon pollution in the southwestern United States

    PubMed Central

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

    2003-01-01

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

  7. Midlatitude D region variations measured from broadband radio atmospherics

    NASA Astrophysics Data System (ADS)

    Han, Feng

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

  8. Influence of Transient Atmospheric Circulation on the Surface Heating of the Pacific Warm Pool

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Chou, Shu-Hsien; Chan, Pui-King

    2003-01-01

    Analyses of data on clouds, winds, and surface heat fluxes show that the transient behavior of basin-wide large-scale circulation has a significant influence on the warm pool sea surface temperature (SST). Trade winds converge to regions of the highest SST in the equatorial western Pacific. These regions have the largest cloud cover and smallest wind speed. Both surface solar heating and evaporative cooling are weak. The reduced evaporative cooling due to weakened winds exceeds the reduced solar heating due to enhanced cloudiness. The result is a maximum surface heating in the strong convective and high SST regions. Data also show that the maximum surface heating in strong convective regions is interrupted by transient atmospheric and oceanic circulation. Due to the seasonal variation of the insolation at the top of the atmosphere, trade winds and clouds also experience seasonal variations. Regions of high SST and low-level convergence follow the Sun, where the surface heating is a maximum. As the Sun moves away from a convective region, the strong trade winds set in, and the evaporative cooling enhances, resulting in a net cooling of the surface. During an El Nino, the maximum SST and convective region shifts eastward from the maritime continent to the equatorial central Pacific. Following the eastward shift of the maximum SST, the region of maximum cloudiness and surface heating also shift eastward. As the atmospheric and oceanic circulation returns to normal situations, the trade winds increase and the surface heating decreases. We conclude that the evaporative cooling associated with the seasonal and interannual variations of trade winds is one of the major factors that modulate the SST distribution of the Pacific warm pool.

  9. 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

  10. Influence of wind direction on pollen concentration in the atmosphere

    NASA Astrophysics Data System (ADS)

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

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

  11. Observational evidences on the influences of tropical lower atmospheric ˜20 day oscillation on the ionospheric equatorial electrojet

    NASA Astrophysics Data System (ADS)

    Ramkumar, T. K.; Bhavanikumar, Y.; Narayana Rao, D.; Gurubaran, S.; Narendra Babu, A.; Ghosh, A. K.; Rajaram, R.

    2006-02-01

    As an observational evidence, it is reported that long period oscillations near 21- and 30-days generated in the lower atmosphere (troposphere and lower stratosphere) in the Indian tropical regions have possible influences on the lower E region ionospheric currents (say equatorial electrojet [EEJ]) at these periodicities. Dynamical parameters like atmospheric wind velocities are measured in the lower atmosphere (4 20 km) and mesosphere (80 98 km) using the Indian MST radar located at Gadanki (a tropical station) and the MF radar located at Tirunelveli (Indian magnetic equatorial station), respectively, during the time interval of 18 January to 23 April 1999. Using Nd-Yag Rayleigh scatter lidar collocated at Gadanki, the atmospheric temperature profiles are measured in the intermediate height range of 25 80 km for the same period of observation. As a lower E region ionospheric parameter, the EEJ current strengths are measured by determining the geomagnetic field strengths at the Indian EEJ and off-EEJ stations of Trivandrum and Alibag, respectively. Analyses of the data by using fast Fourier transform (FFT), wavelet transform (Morlet wavelet), maximum entropy method (MEM) and Lomb Scargle periodogram analysis have indicated that it may be possible for the long period oscillations generated in the lower atmosphere to have influences on the E region ionosphere. Possible influences of the solar high energy radiations and magnetospheric origin on EEJ current systems in the periodicity range of ˜20 30 days are also discussed with illustrations.

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

    NASA Astrophysics Data System (ADS)

    Marčeta, Dušan; Šegan, Stevo; Rašuo, Boško

    2014-05-01

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

  13. Influence of longitudinal argon flow on DC glow discharge at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Zhu, Sha; Jiang, Weiman; Tang, Jie; Xu, Yonggang; Wang, Yishan; Zhao, Wei; Duan, Yixiang

    2016-05-01

    A one-dimensional self-consistent fluid model was employed to investigate the influence of longitudinal argon flow on the DC glow discharge at atmospheric pressure. It is found that the charges exhibit distinct dynamic behaviors at different argon flow velocities, accompanied by a considerable change in the discharge structure. The positive argon flow allows for the reduction of charge densities in the positive column and negative glow regions, and even leads to the disappearance of negative glow. The negative argon flow gives rise to the enhancement of charge densities in the positive column and negative glow regions. These observations are attributed to the fact that the gas flow convection influences the transport of charges through different manners by comparing the argon flow velocity with the ion drift velocity. The findings are important for improving the chemical activity and work efficiency of the plasma source by controlling the gas flow in practical applications.

  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. 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

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

    NASA Astrophysics Data System (ADS)

    Abkar, Mahdi; Porté-Agel, Fernando

    2014-05-01

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

  17. 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.

  18. Terrestrial influence on atmospheric carbon dioxide, a mechanistic study using oxygen-18

    NASA Astrophysics Data System (ADS)

    Fessenden, Julianna Eileen

    The present carbon budget is unbalanced due to anthropogenic influences. Atmospheric warming might have resulted from rising atmospheric carbon dioxide levels. Sequestration of this CO2 is observed in oceans and land vegetation, though questions arise regarding the magnitude of the terrestrial biosphere sink. These questions can be addressed by measuring the abundance of the light stable isotopes of oxygen (16O, and 18O in CO2) in the biological and chemical processes which produce and consume CO2. This work applies known methods of CO2 isolation and mass spectrometric analysis to address questions regarding the mechanisms of isotopic fractionation during land-atmosphere exchange where global, regional, local, and point-spot studies are researched. Atmospheric CO2 exchange with land masses influences about 80% of the delta18O signature yielding exchange fluxes on the order of 200 GtC yr-1. Land biosphere controls the seasonal cycle of CO2 and the offsets observed in the seasonal swing of the isotopic ratios, 13C/12C and 18O/16O (4--6 month shifts). When we looked closer at magnitudes of land-atmosphere exchanges, we saw that the respiratory flux was 100 times greater than the photosynthetic flux during the summer on the day of measurement in a coniferous forest system (3612 mumol m-2 s-1). Therefore, this regional isotopic signature was thought to be dominated by the delta 18O of soil respired CO2. Further inspection of the controlling mechanisms of soil respired CO 2 was then addressed where offsets (20‰) from soil water were observed in moisture limited ridge-top soils. Also, kinetic fractionation due to molecular diffusion through the soil column (thought to be 8.8‰) was not observed within the moisture limited, unsaturated, or saturated conditions within a grassland or forest ecosystem. On a localized scale, we conducted experiments on isotopically tracing water movement in a rooting zone. The results showed increased production of trace gases leading to increased emission rates (shown in CO2). In conclusion, plant ecosystems have a strong influence on isotopic compositions of atmospheric CO2, where fluxes can be monitored with delta 18O.

  19. 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.

  20. The Anthropogenic Influence on Atmospheric Carbonyl Sulfide: Implications for Inverse Analysis of Process-Level Carbon Cycle Fluxes

    NASA Astrophysics Data System (ADS)

    Zumkehr, A. L.; Hilton, T. W.; Whelan, M.; Smith, S. J.; Campbell, J. E.

    2014-12-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing gas in the troposphere and a significant precursor to stratospheric aerosol. Recent insights on the plant uptake of atmospheric COS suggest that plant uptake is the largest component of the global COS budget and that COS may provide a powerful new tool for partitioning sources and sinks of atmospheric CO2 at regional to global scales. However, alternative sources and sinks of COS must also be accounted for to minimize the uncertainty of this carbon cycle tracer approach. Here we focus on direct and indirect sources of atmospheric COS from anthropogenic activities. We construct bottom-up gridded inventories of anthropogenic COS sources and compare these to previous estimates that were based on relatively sparse emissions data. Furthermore, we simulate COS concentrations with an regional atmospheric chemistry model to show the influence of these alternative source estimates in relation to plant uptake at a range of surface and airborne monitoring sites.

  1. Regional Feedbacks Between the Ocean and the Atmosphere in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Thompson, L.; Garcia, M.; Kelly, K. A.; Booth, J. F.

    2012-12-01

    The ocean acts to buffer changes in the climate system with the upper 800m of the ocean taking up more than 90% of the excess heat in the climate system. On interannual time scales, surface heat fluxes damp the low-frequency heat content anomalies in some areas of the ocean where heat anomalies can be released back to the atmosphere. Analysis of satellite altimetry observations of SSH (sea surface height) as a proxy for upper ocean heat content and net suface heat flux from OAFlux (Objectively Analyzed air-sea fluxes) 993-2009 allows the identification of the times of the year and the locations in the North Atlantic where heat content anomalies are driving surface fluxes. Heat content has six month persistence while surface flux has at most one month persistence. Times series for each month of the year at each location are created to examine the lagged correlation between upper ocean heat content and the net surface heat fluxes. The heat content anomalies south of the Gulf Stream in June through November are negatively correlated with surface fluxes in November with a warmer ocean leading to surface fluxes out of the ocean. In this region, the mixed-layer by November reaches 100 m and the previous summer's stored heat is accessible to the atmosphere. The high correlations continue into December and January. By February, the correlation is no longer significant. In the region between 15N and 40N off the coast of Africa, January through May heat content are anti-correlated with surface fluxes in May. In May at this location, the climatological sensible heat flux is into the ocean, the planetary boundary layer is stable and stratocumulus clouds are common. Significant correlations in the summer are also found in the central subpolar North Atlantic. This analysis suggests that locally ocean heat content anomalies can feedback to the atmosphere, but only during certain times of the year. The impact on the atmosphere in late fall and early winter can influence of the atmosphere outside of the planetary boundary layer, although the magnitude of the signal is likely small compared to the intrinsic atmospheric variability. In the regions with summer feedbacks, the impact of the heat released is likely felt only in the planetary boundary layer, although there could be an impact on the radiation balance by ocean forced changes in stratocumulus clouds.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  5. 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).

  6. Influence of aerosols on atmospheric variables in the HARMONIE model

    NASA Astrophysics Data System (ADS)

    Palamarchuk, Iuliia; Ivanov, Sergiy; Ruban, Igor; Pavlova, Hanna

    2016-03-01

    The mesoscale HARMONIE model is used to investigate the potential influence of aerosols on weather forecasts, and in particular, on precipitation. The study considers three numerical experiments over the Atlantic-Europe-Northern Africa region during 11-16 August 2010 with the following configurations: (a) no aerosols, (b) only the sea aerosols, and (c) the four types of the aerosols: sea, land, organic, and dust aerosols. The spatio-temporal analysis of forecast differences highlights the impact of aerosols on the prediction of main meteorological variables such as air temperature, humidity, precipitation, and cloud cover as well as their vertical profiles. The variations occur through changes in radiation fluxes and microphysics properties. The sensitivity experiments with the inclusion of climatological aerosol concentrations demonstrate the importance of aerosol effects on weather prediction.

  7. Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years

    NASA Astrophysics Data System (ADS)

    Han, Y. M.; Wei, C.; Huang, R.-J.; Bandowe, B. A. M.; Ho, S. S. H.; Cao, J. J.; Jin, Z. D.; Xu, B. Q.; Gao, S. P.; Tie, X. X.; An, Z. S.; Wilcke, W.

    2016-01-01

    Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People’s Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980-2012 relative to the period 1850-1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas.

  8. Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years

    PubMed Central

    Han, Y. M.; Wei, C.; Huang, R.-J.; Bandowe, B. A. M.; Ho, S. S. H.; Cao, J. J.; Jin, Z. D.; Xu, B. Q.; Gao, S. P.; Tie, X. X.; An, Z. S.; Wilcke, W.

    2016-01-01

    Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People’s Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980–2012 relative to the period 1850–1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas. PMID:26750586

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

    PubMed

    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 μm (PM10) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m(3), and those for PM10 were 42.8 and 68.9 ng/m(3), in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM10 and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM10 were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N), Gd(N)/Yb(N)). PMID:24657942

  10. 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.

  11. Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years.

    PubMed

    Han, Y M; Wei, C; Huang, R-J; Bandowe, B A M; Ho, S S H; Cao, J J; Jin, Z D; Xu, B Q; Gao, S P; Tie, X X; An, Z S; Wilcke, W

    2016-01-01

    Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People's Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980-2012 relative to the period 1850-1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas. PMID:26750586

  12. 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.

  13. Atmospheric moisture budget during winter seasons in the western Himalayan region

    NASA Astrophysics Data System (ADS)

    Tiwari, Sarita; Kar, Sarat C.; Bhatla, R.

    2016-04-01

    Winter precipitation in the western Himalayas occurs under the influence of western disturbances (WDs) that move in synoptic timescale from west to east across the Himalayan region. The main objective of the study is to examine the water vapor budget during life cycles of WDs using the high-resolution global climate forecast system reanalysis data. It is found that over western Kashmir, even in climatological mean, a westerly trough is seen in moisture flux. Precipitation exceeds evaporation over most of Jammu and Kashmir, Hindukush region and the region to the west in winter seasons. Large interannual variability is noticed in all components of the moisture budget in the region. In order to understand the mechanism of moisture transport and atmospheric moisture budget over study area during the life cycle of WDs, an EOF analysis has been carried out using geopotential height at 500 hPa. The first two leading modes represent eastward moving WDs. Composite analysis of moisture budget (both atmospheric and surface) has been made using the dates from the EOF analysis. It is found that large variations in moisture transport occur during different phases of the WDs. When a cyclonic circulation is around 72°E, strong meridional moisture transport (from Arabian Sea) occurs and moisture convergence over western Himalayas enhances precipitation over the region. After the circulation moves further east, moisture convergence decreases and precipitation reduces. However, evaporation amount increases marginally due to clear sky conditions. During the life cycle of WDs, large variation in meridional transport of moisture flux is noticed as compared to zonal transport.

  14. Isolating mesoscale coupled ocean-atmosphere interactions in the Kuroshio Extension region

    NASA Astrophysics Data System (ADS)

    Putrasahan, Dian A.; Miller, Arthur J.; Seo, Hyodae

    2013-09-01

    The Kuroshio Extension region is characterized by energetic oceanic mesoscale and frontal variability that alters the air-sea fluxes that can influence large-scale climate variability in the North Pacific. We investigate this mesoscale air-sea coupling using a regional eddy-resolving coupled ocean-atmosphere (OA) model that downscales the observed large-scale climate variability from 2001 to 2007. The model simulates many aspects of the observed seasonal cycle of OA coupling strength for both momentum and turbulent heat fluxes. We introduce a new modeling approach to study the scale-dependence of two well-known mechanisms for the surface wind response to mesoscale sea surface temperatures (SSTs), namely, the 'vertical mixing mechanism' (VMM) and the 'pressure adjustment mechanism' (PAM). We compare the fully coupled model to the same model with an online, 2-D spatial smoother applied to remove the mesoscale SST field felt by the atmosphere. Both VMM and PAM are found to be active during the strong wintertime peak seen in the coupling strength in both the model and observations. For VMM, large-scale SST gradients surprisingly generate coupling between downwind SST gradient and wind stress divergence that is often stronger than the coupling on the mesoscale, indicating their joint importance in OA interaction in this region. In contrast, VMM coupling between crosswind SST gradient and wind stress curl occurs only on the mesoscale, and not over large-scale SST gradients, indicating the essential role of the ocean mesocale. For PAM, the model results indicate that coupling between the Laplacian of sea level pressure and surface wind convergence occurs for both mesoscale and large-scale processes, but inclusion of the mesoscale roughly doubles the coupling strength. Coupling between latent heat flux and SST is found to be significant throughout the entire seasonal cycle in both fully coupled mode and large-scale coupled mode, with peak coupling during winter months. The atmospheric response to the oceanic mesoscale SST is also studied by comparing the fully coupled run to an uncoupled atmospheric model forced with smoothed SST prescribed from the coupled run. Precipitation anomalies are found to be forced by surface wind convergence patterns that are driven by mesoscale SST gradients, indicating the importance of the ocean forcing the atmosphere at this scale.

  15. Regional atmospheric circulation shifts induced by a grand solar minimum

    NASA Astrophysics Data System (ADS)

    Martin-Puertas, Celia; Matthes, Katja; Brauer, Achim; Muscheler, Raimund; Hansen, Felicitas; Petrick, Christof; Aldahan, Ala; Possnert, Gran; van Geel, Bas

    2012-06-01

    Large changes in solar ultraviolet radiation can indirectly affect climate by inducing atmospheric changes. Specifically, it has been suggested that centennial-scale climate variability during the Holocene epoch was controlled by the Sun. However, the amplitude of solar forcing is small when compared with the climatic effects and, without reliable data sets, it is unclear which feedback mechanisms could have amplified the forcing. Here we analyse annually laminated sediments of Lake Meerfelder Maar, Germany, to derive variations in wind strength and the rate of 10Be accumulation, a proxy for solar activity, from 3,300 to 2,000 years before present. We find a sharp increase in windiness and cosmogenic 10Be deposition 2,759 +/- 39 varve years before present and a reduction in both entities 199 +/- 9 annual layers later. We infer that the atmospheric circulation reacted abruptly and in phase with the solar minimum. A shift in atmospheric circulation in response to changes in solar activity is broadly consistent with atmospheric circulation patterns in long-term climate model simulations, and in reanalysis data that assimilate observations from recent solar minima into a climate model. We conclude that changes in atmospheric circulation amplified the solar signal and caused abrupt climate change about 2,800 years ago, coincident with a grand solar minimum.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Akhtar, Naveed; Brauch, Jennifer; Ahrens, Bodo

    2014-05-01

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

  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. 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 μm (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.

  3. 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.

  4. A zonally symmetric model for volcanic influence upon atmospheric circulation

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.; Mayr, H. G.; Harris, I.; Taylor, H. A., Jr.

    1984-01-01

    The effects of volcanic activity upon zonal wind flow in a model atmosphere are considered. A low latitude volcanic eruption could lower the tropospheric pole to equator temperature difference and thereby affect the atmospheric motions. When the temperature contrast decreases, the zonal wind velocities at high altitudes are reduced. To conserve angular momentum, the velocities in the lower atmosphere near the surface must increase, thus providing a momentum source for ocean currents. It is suggested that this momentum source may have played a role as a trigger for inducing the 1982-83 anomalous El Nino and possibly other climate changes.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  6. 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-а and Program 22 of the RAS Presidium.

  7. Regional forecasting with global atmospheric models; Fourth year report

    SciTech Connect

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

    1994-05-01

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

  8. Influence of Atmospheric Pressure and Composition on LIBS

    NASA Astrophysics Data System (ADS)

    Scott, Jill R.; Effenberger, Andrew J.; Hatch, Jeremy J.

    While laser-induced breakdown spectroscopy (LIBS) is an attractive technique because of its basic simplicity with little or no sample preparation and ability to be performed under standard Earth atmosphere, there has been increasing interest in performing LIBS under non-standard pressures and with surrounding atmospheric gases other than air. Altering the atmospheric pressure can dramatically change the observed LIBS spectra, such as greatly improving the resolution, signal intensity, and overall signal-to-noise ratio by judicious choice of pressure and gas composition. The ability to enhance LIBS spectra has enabled challenging applications related to detection of isotopes. Interest in non-standard atmospheric conditions is also driven by applications for space exploration and process monitoring as well as the opportunity to better understand the dynamics associated with the LIBS plasma.

  9. Influences of land-ocean-atmosphere dynamics and emissions sectors on atmospheric chemical transport during VOCALS REx

    NASA Astrophysics Data System (ADS)

    Spak, S.; Mena, M.; Carmichael, G. R.

    2009-12-01

    Measurements and modeling from the VOCALS REx campaign have identified a range of transport regimes based on synoptic meteorology, and suggested roles for the marine boundary layer inversion, downslope katabatic winds from the Andean cordillera, and Hadley cell subsidence as primary causes for observed aerosol and trace gas concentration gradients over the Southeast Pacific. This study employs atmospheric chemical transport modeling and airmass trajectory analyses to more directly address the influence of orographic winds, boundary layer dynamics, coastal circulations, and large-scale circulation by the subtropical high on the diurnal and episodic variability of pollution transport in the region. Using hourly simulations with the Weather Research and Forecasting model and the STEM chemical transport model at 12 km x 12 km resolution, we introduce tracer emissions within and above the boundary layer at representative locations--including the western slopes of the Andes, on-shore and off-shore coastal areas, metropolitan Santiago, the Chilean altiplano, and the free troposphere over the open ocean--and follow their transport and fate throughout the REx experiment of October-November 2008. Comparison between trajectories and tracer concentrations illustrate long range airmass history and allow for an understanding of the representativeness of instantaneous trajectories on transport phenomena. We further assess the contributions of emissions from power generation, copper smelters, natural sources, and anthropogenic area sources to aerosol concentrations over the Southeast Pacific, identifying their role in each transport regime.

  10. 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.

  11. 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...

  12. 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.

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

    PubMed

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

    2015-12-01

    Atmospheric mercury deposition by wet and dry processes contributes to the transformation of mercury from atmosphere to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to subtropical forests were identified in this study. Throughfall and open field precipitation samples were collected in 2012 and 2013 using precipitation collectors from forest sites located across Mt. Jinyun in southwest China. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy was the primary factor on THg and MeHg deposition. Simultaneously, continuous measurements of atmospheric gaseous elemental mercury (GEM) were carried out from March 2012 to February 2013 at the summit of Mt. Jinyun. Atmospheric GEM concentrations averaged 3.8 ± 1.5 ng m(-3), which was elevated compared with global background values. Sources identification indicated that both regional industrial emissions and long-range transport of Hg from central, northeast, and southwest China were corresponded to the elevated GEM levels. Precipitation deposition fluxes of THg and MeHg in Mt. Jinyun were slightly higher than those reported in Europe and North America, whereas total fluxes of MeHg and THg under forest canopy on Mt. Jiuyun were 3 and 2.9 times of the fluxes of THg in wet deposition in the open. Highly elevated litterfall deposition fluxes suggest that even in remote forest areas of China, deposition of atmospheric Hg(0) via uptake by vegetation leaf may be a major pathway for the deposition of atmospheric Hg. The result illustrates that areas with greater atmospheric pollution can be expected to have greater fluxes of Hg to soils via throughfall and litterfall. PMID:26298336

  14. Ionospheric E-region electron density and neutral atmosphere variations

    NASA Technical Reports Server (NTRS)

    Stick, T. L.

    1976-01-01

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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Stellar activity and its influence on planetary atmosphere evolution

    NASA Astrophysics Data System (ADS)

    Lammer, H.; Khodachenko, M. L.; Kislyakova, K. G.; Weingrill, J.; Kulikov, Y. N.; Holmström, M.; Zaqarshvili, T. V.; Odert, P.; Leitzinger, M.; Fichtinger, B.; Güdel, M.; Ribas, I.; Hanslmeier, A.; Shematovich, V. I.; Bisikalo, D.

    2011-10-01

    The evolution of planetary atmospheres can only be understood if one recognizes the fact that the radiation and particle environment of the Sun or a planet's host star were not always on the same activity level. New insights, the latest observations and research regarding the evolution of the solar radiation, plasma environment and solar/stellar magnetic field from the observations of solar proxies and their impact on planetary atmospheres with different ages will be given. We present also a new innovative idea how hydrogen coronae and energetic neutral atom (ENA) observations around transiting Earth-like exoplanets by space observatories such as the WSO-UV, can be used for testing the addressed atmospheric evolution studies.

  20. 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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  2. Nimbus 4 IRIS spectra in the 750-1250/cm atmospheric window region

    NASA Technical Reports Server (NTRS)

    Kunde, V. G.; Conrath, B. J.; Hanel, R. A.; Prabhakara, C.

    1973-01-01

    Several Nimbus 4 IRIS spectra are presented for the 700-1300/cm region as examples of free atmosphere spectra to illustrate problems encountered in interpreting window measurements. Several atmospheric windows near 936 and 960/cm appear significantly more transparent than the 899/cm window presently used in operational remote sensing systems.

  3. 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.

  4. A regional coupled atmospheric-ocean model suitable for hydrological studies

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  5. The solar atmosphere and the structure of active regions

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.

    1974-01-01

    The existence of 'holes' in the corona is reported characterized by abnormally low densities and temperatures. It was found that such coronal holes appear to be the source of high-velocity, enhanced-density streams in the solar wind as observed at the earth's orbit. It was further noted that coronal holes appear to be associated with regions of diverging magnetic fields in the corona. Models were developed to accomplish the objective for the principal energy flows in the transition region and corona.

  6. 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.

  7. Influence of atmospheric structure and topography on infrasonic wave propagation

    NASA Astrophysics Data System (ADS)

    Lacanna, G.; Ichihara, M.; Iwakuni, M.; Takeo, M.; Iguchi, M.; Ripepe, M.

    2014-04-01

    The effects of topography and atmospheric structures on infrasonic wave propagation from a volcanic source were investigated using observations and numerical modeling. This paper presents the first long-term observational data set showing spatiotemporal variations in patterns of infrasound propagation at distances of up to 60 km from a persistently active infrasound source (Sakurajima Volcano, Japan). The data show that the amplitudes of infrasonic waves received at distant stations relative to those received at a reference station close to the source can vary up to an order of magnitude over short time intervals and short distances and that they do not follow the theoretical geometric decay expected for homogeneous media. Moreover, waveforms also change significantly in both time and space. Numerical simulations were performed using a two-dimensional finite difference time domain (2-D FDTD) method. Effects of atmospheric structure and topography are included in a vertical section parallel to the wave propagation direction. The simulation successfully reproduced the variations of amplitudes and waveforms. Results are interpreted in terms of wave refraction due to sound and wind speed gradients and wave diffraction at topographic barriers. Our numerical results indicate that both atmospheric and topographic propagation effects are nonnegligible. To evaluate the propagation effects and determine source processes in spatially and temporally varying infrasound data, atmospheric data with a time resolution higher than is currently available are required. If the data are available, the present results suggest that the propagation effects could be evaluated using 2-D FDTD modeling at realistic calculation times.

  8. Influence of Mesoscale Ocean Wind Variability on Tropical Atmospheric Convection

    NASA Astrophysics Data System (ADS)

    Choi, S.; Nesbitt, S. W.; Lang, T. J.; Chronis, T.

    2014-12-01

    The atmosphere and ocean are tightly coupled elements of the climate system, yet many of their interactions remain poorly understood. In particular, our knowledge of the relationship between precipitation and synoptic/mesoscale sea surface wind patterns suffers due to the lack of observations over the ocean. Satellite-based scatterometer wind retrievals, with their ability to observe surface winds near rainfall, coupled with atmospheric reanalysis enable the investigation of the relationships between flows and surface atmosphere exchanges of water and energy near precipitation. In this study, we examine the interactions between surface wind features and the oceanic state, and the kinematic and thermodynamic environment surrounding heavy rain producing oceanic tropical convective systems (excluding tropical cyclones). Three-hourly rainfall data from the TRMM product 3B42 are used to identify extreme precipitation events, and composites of surrounding meteorological fields are examined to understand the forcing and maintenance of these systems. Atmosphere-ocean surface heat and moisture fluxes are analyzed with corresponding meteorological fields provided by MERRA reanalyses, as well as bulk aerodynamic formulae using scatterometer data. In addition, QuikSCAT, ASCAT, and RapidSCAT are used to represent surface wind data surrounding the precipitation systems in question, and differences between MERRA and scatterometer near surface winds are investigated. The goal of this research is to understand the co-evolution of surface wind kinematic features and heavy precipitation, and their water and energy budgets in intense oceanic tropical rainfall.

  9. Surface-Atmosphere Moisture Coupling in Eurasian Frozen Ground Regions

    NASA Astrophysics Data System (ADS)

    Frauenfeld, O. W.; Ford, T.

    2014-12-01

    Permafrost represents an impermeable barrier to moisture, resulting in a saturated or near-saturated surface layer during the warm season in many continuous and discontinuous permafrost zones. These surface conditions could lead to enhanced convection and precipitation during the warm season, and significant local recycling of moisture. In areas underlain by sporadic or isolated permafrost, or in seasonally frozen areas, the moisture can drain away more readily, resulting in much drier soil conditions. As climate change causes frozen ground degradation, this will thus also alter the patterns of atmospheric convection, moisture recycling, and the hydrologic cycle in high-latitude land areas. In this study, we analyze evaporative fraction (EF) as a proxy for evapotranspiration, and precipitation from the Modern-Era Retrospective analysis for Research and Applications (MERRA-land) reanalysis dataset. We focus on 1979-2012 and document patterns and changes in EF over the Eurasian high latitudes. We find strong, positive April EF trends over the study period, particularly in the Lena River Basin, 80% of which is underlain by continuous permafrost. In fact, these significant positive trends in spring EF are strongest over continuous permafrost across the Eurasian high latitudes, but negative for sporadic and isolated permafrost. In addition, we find a strong, statistically significant relationship between EF anomalies and the probability of subsequent precipitation over the Lena Basin during April. This association therefore suggests a potential land-atmosphere coupling between frozen ground and precipitation. As the permafrost and seasonally frozen ground distribution changes in the future, this will likely have repercussions for the Arctic hydrologic cycle.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    We take advantage of the spatial coverage provided by the Tropospheric Emission Spectrometer on-board the Aura satellite to evaluate processes that control seasonal variations in atmospheric water vapor HDO/H2O values (δDvapor) over the tropical Andes. δDvapor is lower in austral summer (December, January, and February, DJF) than austral winter (June, July, and August, JJA), which is broadly consistent with precipitation studies and with δ18Osnow preserved in tropical Andean glaciers. In DJF, 64% of δDvapor measurements over the tropical Andes are lower than predicted by Rayleigh distillation while 40% of JJA δDvapor measurements are lower than predicted by Rayleigh distillation. Air that has lower δDvapor than predicted by Rayleigh distillation at a given water vapor concentration (q) encounters low minimum outgoing longwave radiation (<240 W m-2) en route to the tropical Andes, suggesting convective intensity controls the isotopic ratios of these measurements. The broad regional coverage of the satellite data allows us to map the spatial extent of the region where isotopic ratios reflect convective processes in different seasons. In DJF, convection strongly influences δDvapor in the central tropical Andes. In JJA, convection influences δDvapor north of the tropical Andes. This pattern suggests that monsoon convection controls δDvapor in austral summer while large-scale advective mixing controls Andean δDvapor in austral winter.

  11. 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...

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

    PubMed

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

    2015-02-17

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

  13. Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  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. 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.

  18. Longitudinal variations in the Saturnian atmosphere. I - Equatorial region

    NASA Astrophysics Data System (ADS)

    Killen, R. M.

    1988-02-01

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

  19. 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.

  20. Influence of a sample surface on single electrode atmospheric plasma jet parameters

    NASA Astrophysics Data System (ADS)

    Zaplotnik, Rok; Bišćan, Marijan; Kregar, Zlatko; Cvelbar, Uroš; Mozetič, Miran; Milošević, Slobodan

    2015-01-01

    The article reports on reciprocal influence between the sample surface and atmospheric plasma jet. This correlation is important since it changes plasma parameters and plasma itself, depending on the sample-material surface, presence of liquid or treatment distance. However, in experiments and treatments of surfaces with atmospheric plasma jets, this relationship is usually disregarded. In order to investigate reciprocal influence, we implemented electromagnetic and optical emission spectroscopy characterization of atmospheric plasma needle jet. Characterization was performed during treatment of various samples. We have shown that sample material and its distance from the tip of the electrode have a pronounced influence on atmospheric pressure plasma jet electromagnetic and optical characteristics, such as jet length, shape, color, voltage, current, power, electromagnetic field and concentrations of plasma species. It was shown that for a given flow there is a critical distance (≈ 15 mm) between the tip of the wire and the sample surface for which jet emission intensity, especially ionic, is at maximum.

  1. An objective prior error quantification for regional atmospheric inverse applications

    NASA Astrophysics Data System (ADS)

    Kountouris, P.; Gerbig, C.; Totsche, K.-U.; Dolman, A. J.; Meesters, A. G. C. A.; Broquet, G.; Maignan, F.; Gioli, B.; Montagnani, L.; Helfter, C.

    2015-12-01

    Assigning proper prior uncertainties for inverse modelling of CO2 is of high importance, both to regularise the otherwise ill-constrained inverse problem and to quantitatively characterise the magnitude and structure of the error between prior and "true" flux. We use surface fluxes derived from three biosphere models - VPRM, ORCHIDEE, and 5PM - and compare them against daily averaged fluxes from 53 eddy covariance sites across Europe for the year 2007 and against repeated aircraft flux measurements encompassing spatial transects. In addition we create synthetic observations using modelled fluxes instead of the observed ones to explore the potential to infer prior uncertainties from model-model residuals. To ensure the realism of the synthetic data analysis, a random measurement noise was added to the modelled tower fluxes which were used as reference. The temporal autocorrelation time for tower model-data residuals was found to be around 30 days for both VPRM and ORCHIDEE but significantly different for the 5PM model with 70 days. This difference is caused by a few sites with large biases between the data and the 5PM model. The spatial correlation of the model-data residuals for all models was found to be very short, up to few tens of kilometres but with uncertainties up to 100 % of this estimation. Propagating this error structure to annual continental scale yields an uncertainty of 0.06 Gt C and strongly underestimates uncertainties typically used from atmospheric inversion systems, revealing another potential source of errors. Long spatial e-folding correlation lengths up to several hundreds of kilometres were determined when synthetic data were used. Results from repeated aircraft transects in south-western France are consistent with those obtained from the tower sites in terms of spatial autocorrelation (35 km on average) while temporal autocorrelation is markedly lower (13 days). Our findings suggest that the different prior models have a common temporal error structure. Separating the analysis of the statistics for the model data residuals by seasons did not result in any significant differences of the spatial e-folding correlation lengths.

  2. Regional model studies of the atmospheric dispersion of fine volcanic ash after the eruption of Eyjafjallajoekull

    NASA Astrophysics Data System (ADS)

    Langmann, B.; Hort, M. K.

    2010-12-01

    During the eruption of Eyjafjallajoekull on Iceland in April/May 2010 air traffic over Europe was repeatedly interrupted because of volcanic ash in the atmosphere. This completely unusual situation in Europe leads to the demand of improved crisis management, e.g. European wide regulations of volcanic ash thresholds and improved forecasts of theses thresholds. However, the quality of the forecast of fine volcanic ash concentrations in the atmosphere depends to a great extent on a realistic description of the erupted mass flux of fine ash particles, which is rather uncertain. Numerous aerosol measurements (ground based and satellite remote sensing, and in situ measurements) all over Europe have tracked the volcanic ash clouds during the eruption of Eyjafjallajoekull offering the possibility for an interdisciplinary effort between volcanologists and aerosol researchers to analyse the release and dispersion of fine volcanic ash in order to better understand the needs for realistic volcanic ash forecasts. This contribution describes the uncertainties related to the amount of fine volcanic ash released from Eyjafjallajoekull and its influence on the dispersion of volcanic ash over Europe by numerical modeling. We use the three-dimensional Eulerian atmosphere-chemistry/aerosol model REMOTE (Langmann et al., 2008) to simulate the distribution of volcanic ash as well as its deposition after the eruptions of Eyjafjallajoekull during April and May 2010. The model has been used before to simulate the fate of the volcanic ash after the volcanic eruptions of Kasatochi in 2008 (Langmann et al., 2010) and Mt. Pinatubo in 1991. Comparing our model results with available measurements for the Eyjafjallajoekull eruption we find a quite good agreement with available ash concentrations data measured over Europe as well as with the results from other models. Langmann, B., K. Zakšek and M. Hort, Atmospheric distribution and removal of volcanic ash after the eruption of Kasatochi volcano: A regional model study, J. Geophys. Res., 115, D00L06, doi:10.1029/2009JD013298, 2010. Langmann, B., S. Varghese, E. Marmer, E. Vignati, J. Wilson, P. Stier and C. O’Dowd, Aerosol distribution over Europe: A model evaluation study with detailed aerosol microphysics, Atmos. Chem. Phys. 8, 1591-1607, 2008.

  3. 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 δ18O and δD 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 (δv) is δ18O = -14.66 ‰ and δD = - 95.4 ‰, with data plotting clearly above the local meteoric water line on a δ18O-δD 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 δv 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 δv depletion with d remaining stable. Using a two-component mixing model, we calculate the average composition of the locally evaporated vapour (δE). We find higher d(E) under North Atlantic air mass conditions, which is consistent with lower humidity conditions. We also suggest that δv 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 (δE) to the ambient moisture (δv). 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.

  4. 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 β-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

  5. Studies of regional-scale climate variability and change. Hidden Markov models and coupled ocean-atmosphere modes

    SciTech Connect

    Ghil, M.; Kravtsov, S.; Robertson, A. W.; Smyth, P.

    2008-10-14

    This project was a continuation of previous work under DOE CCPP funding, in which we had developed a twin approach of probabilistic network (PN) models (sometimes called dynamic Bayesian networks) and intermediate-complexity coupled ocean-atmosphere models (ICMs) to identify the predictable modes of climate variability and to investigate their impacts on the regional scale. We had developed a family of PNs (similar to Hidden Markov Models) to simulate historical records of daily rainfall, and used them to downscale GCM seasonal predictions. Using an idealized atmospheric model, we had established a novel mechanism through which ocean-induced sea-surface temperature (SST) anomalies might influence large-scale atmospheric circulation patterns on interannual and longer time scales; we had found similar patterns in a hybrid coupled ocean-atmosphere-sea-ice model. The goal of the this continuation project was to build 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 results from the grant 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 results; and, observational studies of decadal and multi-decadal natural climate results, informed by ICM results.

  6. The evolution of solar ultraviolet luminosity. [influence on planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Walker, J. C. G.

    1982-01-01

    Astronomical observations of stars analogous to the sun are used to construct a tentative account of the evolution of solar UV luminosity. Evidence exists that the young sun was a much more powerful source of energetic particles and radiation than it is today, and while on the main sequence, solar activity has declined as an inverse power law of age as a consequence of angular momentum loss to the solar wind. Observations of pre-main sequence stars indicate that before the sun reached the main sequence, it may have emitted as much as ten thousand times the amount of ultraviolet radiation that it does today. The impact of the results on knowledge of photochemistry and escape of constituents of primordial planetary atmospheres is discussed.

  7. Measurements of atmospheric stability in the mesopause region at starfire optical range, NM

    NASA Astrophysics Data System (ADS)

    Zhao, Yucheng; Liu, Alan Z.; Gardner, Chester S.

    2003-01-01

    The structure and seasonal variations of static (convective) and dynamic (shear) instabilities in the mesopause region (80-105km) are examined using high-resolution wind and temperature data obtained with a Na lidar at the Starfire Optical Range, NM. The probabilities of static and dynamic instability are sensitive functions of N2/S2, where /N is the buoyancy frequency and /S is the total vertical shear in the horizontal winds. The mesopause region is most stable in summer when the mesopause is low, /N is large and /S is small. Monthly mean N2/S2 varies from a maximum value of about 1.06 in mid-summer to a minimum of 0.68 in January. The annual mean values of /N and /S are, respectively, 0.021s-1 and 23ms-1km-1. The probabilities of static and dynamic instabilities are maximum in mid-winter when they average about 10% and 12%, respectively, and are minimum in summer when they average about 7% and 5%, respectively. The observations are generally consistent with theoretical predictions based on Gaussian models for the temperature and wind fluctuations induced by gravity waves. They also show that statically unstable conditions are generally preceded by dynamically unstable conditions. The instability probabilities vary considerably from night to night and the structure of the unstable regions are significantly influenced by atmospheric tides. Tides alone are usually not strong enough to induce instability but they can establish the environment for instabilities to develop. As the tidal temperature perturbations propagate downward, they reduce the stability on the topside of the positive temperature perturbation. Instabilities are then induced as gravity waves propagate through this layer of reduced static stability.

  8. 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.

  9. 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.

  10. Spectroscopy in the study of planetary atmospheres - Abundances from the visible region

    NASA Technical Reports Server (NTRS)

    Lutz, B. L.

    1978-01-01

    Spectrophotometric studies of three molecular constituents - hydrogen, methane, and ammonia - identified in the visible region of the spectra of the outer planets are reviewed. The history of quadrupole line observations for hydrogen molecules and the significance of the HD molecule for the dipole spectrum are considered. Approaches to quantitative estimates of methane concentration in planetary atmospheres are explained, and the detection of ammonia in the atmospheres of Jupiter and Saturn is described.

  11. 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.

  12. On empirical models of the upper atmosphere in the polar regions.

    NASA Technical Reports Server (NTRS)

    Blum, P. W.; Harris, I.

    1973-01-01

    The expression for the exospheric temperature in Jacchia's static diffusion models of the upper atmosphere has a discontinuous gradient at the poles. Therefore it cannot describe the true state of the upper atmosphere in the polar regions. Furthermore, it cannot be used to calculate quantities that depend on the derivative of the exospheric temperature, or the density, like pressure gradients, horizontal forces or horizontal heat fluxes. A modified expression for the exospheric temperature is suggested. This modification yields variables of state of the upper atmosphere that deviate little from Jacchia's values, but it has continuous gradient at the poles and is therefore more suitable for treating dynamical problems like the global wind pattern.

  13. The influence of orography on the transport of atmospheric constituents

    NASA Technical Reports Server (NTRS)

    Joshi, Manoj M.; Lewis, Stephen R.; Read, Peter L.

    1993-01-01

    Given the fact that martian orography varies over a range of two scale heights (cf., about one scale height on Earth), it is thought that on Mars some aspects of the circulation should be affected to a large degree by the presence of orography. Initial results from two numerical models are presented that illustrate the effect of orography on cross-equatorial transport on Mars. On Earth, western boundary currents are found not only in the oceans as one would expect, but also in the troposphere, the most notable example being the East African Jet, which has an important effect on the monsoon circulation of the Eastern Indian Ocean. Two models were used for this investigation: a simple GCM (hereafter referred to as the SGCM); and a simple one-level barotropic model (BM). The SGCM solves the hydrostatic primitive equations on a sphere by representing model variables by spherical harmonics in the horizontal, with nonlinear terms being calculated in grid-point space. In the vertical, the model uses the sigma coordinate system in finite-difference form. The model represents the radiative processes in the atmosphere by a Newtonian relaxation to a specified zonal mean temperature state and surface drag by Rayleigh friction in the lowest model level.

  14. The ORCA West Coast Regional Project - Atmospheric Top-Down Modeling to constrain Regional Carbon Budgets at high Temporal and Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Goeckede, M.; Michalak, A. M.; Vickers, D.; Turner, D.; Law, B.

    2008-12-01

    The ORCA project aims at determining the regional carbon balance of Oregon, California and Washington, with a special focus on the effect of disturbance history and climate variability on carbon sources and sinks. ORCA provides a regional test of the overall NACP strategy by demonstrating bottom-up and top-down modeling approaches to derive carbon balances at subregional to regional scales. The ORCA top-down modeling component has been set up to capture flux variability on the regional scale at high temporal and spatial resolution. Atmospheric transport is simulated coupling the mesoscale model WRF (Weather Research and Forecast) with the STILT (Stochastic Time Inverted Lagrangian Transport) footprint model. This setup allows identifying sources and sinks that influence atmospheric observations with highly resolved mass transport fields and realistic turbulent mixing. High-precision atmospheric CO2 concentrations are monitored as continuous time series in hourly timesteps at 5 locations within the model domain, west to east from the Pacific Coast to the Great Basin, and include two flux sites for evaluation of computed fluxes. Terrestrial biosphere carbon fluxes are simulated at an effective spatial resolution of smaller than 1km and subdaily timesteps, considering effects of ecoregion, land cover type and disturbance regime on the carbon budgets. Flux computation assimilates high-resolution remote sensing products (e.g. LandSat, MODIS) and interpolated surface meteorology (DayMet, SOGS, PRISM). We present results on regional carbon budgets for the ORCA modeling domain that have been optimized using Bayesian inversion and the information provided by the network of high-precision CO2 observations. We address the influence of spatial and temporal resolution in the general modeling setup on the findings, and test the level of detail that can be resolved by top-down modeling on the regional scale, given the uncertainties introduced by various sources for model-data mismatch. Application of the approach highlights the strong regional variability in CO2 exchange rates on the regional scale. For Oregon, we found that this type of model must account for water availability and drought stress to avoid overestimating terrestrial sinks for CO2.

  15. A new coupled Atmosphere-Ocean Regional Climate Model: study of the Eastern Mediterranean Transient

    NASA Astrophysics Data System (ADS)

    Dubois, Clotilde; Calmanti, Sandro; Sevault, Florence; Somot, Samuel

    2010-05-01

    The Mediterranean sea is an active semi-enclosed marginal sea which communicates with the Atlantic ocean through the Strait of Gibraltar. Its ideal configuration provides an opportunity to investigate hydrological mechanisms and heat and freshwater budgets over its basin. These surface fluxes and their variability at various temporal and spatial scale influence the formation of the Mediterranean water masses. Modeling the mean behavior, the decadal variability and the trends of the Mediterranean sea water is a challenging task and important for future climate change scenarios. A new coupled Atmosphere-Ocean Regional Climate Model (AORCM) forced by ERA40 as boundary conditions simulates the recent climate from 1959 to 2001. A validation of the modeled heat or freshwater budget of the Mediterranean basin is done in comparison with a large panel of observation datasets. The Eastern Mediterranean Transient (EMT) which occurred in the early 1990's formed over those winter large amount of dense Cretan Deep water. This dense water then cascaded and spread into the Eastern basin. For the first time the EMT event is studied in a realistic frame using a high-resolution coupled model with no constraint on the spatio-temporal variability of the air-sea fluxes. Preconditioning step, air-sea fluxes over the Aegean Sea, water mass formation in the Cretan basin, cascading and spreading of the newly formed water in the Eastern Mediterranean is analysed

  16. Atmospheric Response of an Active Region to New Small Flux Emergence

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  17. Proximate humid and dry regions in Jupiter's atmosphere indicate complex local meteorology.

    PubMed

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

    2000-05-11

    Models of Jupiter's formation and structure predict that its atmosphere is enriched in oxygen, relative to the Sun, and that consequently water clouds should be present globally near the 5-bar pressure level. Past attempts to confirm these predictions have led to contradictory results; in particular, the Galileo probe revealed a very dry atmosphere at the entry site, with no significant clouds at depths exceeding the 2-bar level. Although the entry site was known to be relatively cloud-free, the contrast between the observed local dryness and the expected global wetness was surprising. Here we analyse near-infrared (around 5 microm) observations of Jupiter, a spectral region that can reveal the water vapour abundance and vertical cloud structure in the troposphere. We find that humid and extremely dry regions exist in close proximity, and that some humid regions are spatially correlated with bright convective clouds extending from the deep water clouds to the visible atmosphere. PMID:10821265

  18. Sensitivity of boreal-summer circulation and precipitation to atmospheric aerosols in selected regions &ndash Part 2: The Americas

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    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 South America, an increase in precipitation over Central America and the Caribbean, and an enhancement of convergence in the North American monsoon region.

  19. 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.

  20. Vertical variations in the influence of the amount effect: South American Summer Monsoon Region

    NASA Astrophysics Data System (ADS)

    Samuels-Crow, K. E.; Galewsky, J.; Worden, J. R.

    2014-12-01

    Recent theoretical studies have shown that convective recycling of atmospheric water vapor gives rise to the isotope "amount effect" in which d values are lower than predicted by simple Rayleigh distillation processes (i.e. (DdD = dDvapor ­- dDRayleigh < 0‰). Several studies have linked isotopes in precipitation [e.g. Vimeux et al., 2009] and atmospheric water vapor [e.g. Samuels-Crow et al., 2014] in the tropical Andes to upwind convection associated with the South American Summer Monsoon (SASM). The vertical structure of this convective influence, however, remains unknown. Understanding the vertical structure of the amount effect over South America is essential for improving theoretical constraints and developing better models of the influence of the SASM on southern hemisphere humidity. Additionally, evaluating the vertical and lateral extent of the SASM's convective influence can provide important constraints for interpreting paleoclimate proxies in the region. We use data from the Tropospheric Emission Spectrometer (TES) to examine the vertical structure of the amount effect associated with the SASM and relate these results to regional convective precipitation and local subcloud equivalent potential temperature. Preliminary results show that DdD is below 0‰ from the boundary layer through the mid-troposphere over tropical South America during austral summer, and meridional averages show that convective precipitation is highest over these areas where DdD < 0‰ extends higher in the atmosphere. We hypothesize that the depth of convection in the monsoon region controls the vertical structure of DdD, which should also be coherently linked to local equivalent potential temperature. References Vimeux et al. (2009), Palaeogeogr Palaeocl, 281(3-4), 229-241, doi:10.1016/j.palaeo.2008.03.054. Samuels-Crow et al. (2014), J Geophys Res-Atmos, doi:10.1002/(ISSN)2169-8996.

  1. Atmospheric modes influence on the inter- annual variability of the Iberian Poleward Current from 1985 to 2006

    NASA Astrophysics Data System (ADS)

    Decastro, M.; Gómez-Gesteira, M.; Álvarez, I.; Crespo, A. J. C.; Ramos, A. M.

    2009-04-01

    The inter-annual variability of the Iberian poleward current (IPC) along the northwestern coast of the Iberian Peninsula (IP) (40- 43N) and its intrusion in the Cantabrian Sea (Navidad, 6- 8W) were analyzed. The January Sea Surface Temperature (J SST) was obtained from the advanced very high resolution radiometer (AVHRR) NOAA satellite from 1985 to 2006. In addition, the dependence of IPC SST on the most representative regional patterns with some influence upon the eastern North Atlantic region was analyzed by means of correlations between November- December atmospheric modes and J SST. The considered modes were: North Atlantic Oscillation pattern (NAO), Eastern Atlantic pattern (EA), Eastern Atlantic Western Russia pattern (EA/WR), Polar/Eurasia pattern (POL) and Scandinavia pattern (SCA). In the present study it has been highlighted that: (1) there are several years (1986, 1987, 1992, 1995, 1997, 1999, 2004 and 2005) during which water in the IPC region is colder than the oceanic one remarking a weak or inexistent IPC during these Januaries and (2) three atmospheric patterns (N-D NAO, N-D EA/WR and N-D POL) are responsible of the main variability of the J SST in the IPC region of the western IP and only two indices (N-D EA/WR, N-D NAO) have shown to be significant to explain the variability of the J SST in the IPC region of the northern IP region.

  2. California reanalysis downscaling at 10 km using an ocean-atmosphere coupled regional model system

    NASA Astrophysics Data System (ADS)

    Li, Haiqin; Kanamitsu, Masao; Hong, Song-You

    2012-06-01

    A fully coupled regional downscaling system based on the Regional Spectral Model (RSM) for atmosphere and the Regional Ocean Modeling System (ROMS) for the ocean was developed for the purpose of downscaling observed analysis or global model outputs. The two models share the same grid and resolution with efficient parallelization through the use of dual message passing interfaces. Coupled downscaling was performed using historical Simple Ocean Data Assimilation (SODA) oceanic reanalysis and NCEP/DOE (R-2) atmospheric reanalysis in order to study the impact of coupling on the regional scale atmospheric analysis. The results were subsequently compared with the uncoupled downscaling forced by the prescribed observed sea surface temperature (SST). The coupled experiment yielded the SST and ocean current with realistic small-scale oceanic features that are almost absent in the oceanic reanalysis. Upwelling over the California coast is well resolved and comparable to findings obtained from high-resolution observations. The coupling impact on the atmospheric circulation mainly modulates the near surface atmospheric variables when compared to the simulation conducted without coupling. The duration of the Catalina Eddy detected in the coupled experiment increased by about 6.5% when compared to that in the uncoupled experiment. The offshore land breeze is enhanced by about 10%, whereas the change in the onshore sea breeze is very small during the summer.

  3. Influence of atmospheric deposition on Okefenokee National Wildlife Refuge

    USGS Publications Warehouse

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

    1995-01-01

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

  4. Influence of atmospheric deposition on Okefenokee National Wildlife Refuge

    SciTech Connect

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

    1995-12-31

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  6. Simulation of Arctic Climate with the Regional Arctic System Model (RASM): Sensitivity to Atmospheric Processes

    NASA Astrophysics Data System (ADS)

    Cassano, J. J.; Duvivier, A.; Hughes, M.; Roberts, A.; Brunke, M.; Craig, A.; Fisel, B. J.; Gutowski, W. J., Jr.; Maslowski, W.; Nijssen, B.; Osinski, R.; Zeng, X.

    2014-12-01

    A new regional Earth system model of the Arctic, the Regional Arctic System Model (RASM), has recently been developed. The initial version of this model includes atmosphere (WRF), ocean (POP), sea ice (CICE), and land (VIC) component models coupled with the NCAR CESM CPL7 coupler. The model is configured to run on a large pan-Arctic domain that includes all sea ice covered waters in the Northern Hemisphere and all Arctic Ocean draining land areas. Results from multi-decadal (1979 to present) simulations with RASM will be presented and will focus on the model climate's sensitivity to atmospheric processes and a comparison of the fully coupled model and atmosphere-only simulations. The modeled radiation budget, and sea ice cover, was found to be sensitive to the details of the cloud and radiation parameterizations in the atmospheric component (WRF) of RASM, including details of cloud droplet size. Another model sensitivity was found in relation to atmosphere-land processes. Care is needed to ensure that decoupling between the atmosphere and land do not occur under strongly stable conditions over land areas in winter. Comparison of RASM near surface climate with that simulated with stand-alone WRF show areas of both improved and degraded results. Improvement in the coupled model climate are related to more physically realistic representation of coupled processes such as energy transfer from the ocean to the atmosphere through leads in the sea ice during winter. Degraded results come from feedbacks in model component biases, such as atmospheric circulation biases resulting in incorrect local sea ice cover that then result in large local atmospheric temperature biases.

  7. 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.

  8. 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.

  9. 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.

  10. Quantifying Carbon-Climate Processes at the Regional Scale Using Atmospheric Carbonyl Sulfide

    SciTech Connect

    Campbell, Elliott; Berry, Joe; Torn, Margaret; David, Billesbach; Seibt, Ulrike

    2013-10-08

    Atmospheric carbonyl sulfide (COS) analysis has the potentially transformative capability for partitioning the regional carbon flux into respiration and photosynthesis components. This emerging approach is based on the observation that continental atmospheric CO2 gradients are dominated by net ecosystem fluxes while continental atmospheric COS gradients are dominated by photosynthesis-related plant uptake. Regional flux partitioning represents a critical knowledge gap due to a lack of robust methods for regional-scale flux partitioning and large uncertainties in forecasting carbon-climate feedbacks. Our completed project characterized the relationship between COS and CO2 surface fluxes using a novel measurement and modeling system in a winter wheat field at the U.S. Department of Energy?s Atmospheric and Radiation Measurement program Central Facility (DOE-ARM CF). The scope of this project included canopy flux measurements, soil flux measurements, regional atmospheric modeling, and analysis of COS and CO2 airborne observations at SGP. Three critical discoveries emerged from this investigation: (1) the new measurement system provided the first field evidence of a robust relationship between COS leaf fluxes and GPP; (2) a previously unknown seasonal soil source of COS was observed and characterized; (3) the regional atmospheric analysis of airborne measurements provided the first COS-based constraints on GPP parameterizations used in earth systems models. Dissemination of these results includes three publications [Billesbach et al., In Press; Campbell et al., In Preparation; Seibt et al., In Review], three presentations at the AGU Fall Meeting (2012), and four invited presentations to department seminars. We have leveraged this foundational project to continue our work on understanding carbon cycle processes at large scales through one funded project (DOE Lab Fee, 2012-2015) and one proposal that is under review (DOE/NASA/USDA/NOAA, 2014-2016).

  11. 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.

  12. 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.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Strong, Shadrian B.; Brown, Andrea M.

    2014-05-01

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

  16. The atmospheric frontal response to SST perturbations in the Gulf Stream region

    NASA Astrophysics Data System (ADS)

    Parfitt, Rhys; Czaja, Arnaud; Minobe, Shoshiro; Kuwano-Yoshida, Akira

    2016-03-01

    The link between sea surface temperature (SST) gradients and atmospheric fronts is explored in a general circulation model across the Gulf Stream (GS) region from December to February 1981-2000. Two model experiments are analyzed, one with a realistic control SST distribution and one with a spatially smoothed SST distribution. The analysis shows a noticeable change in regional atmospheric frontal frequency between the two experiments (up to 30%), with the distribution of change exhibiting a clear imprint of the GS SST front. Further analysis of the surface sensible heat flux gradient across cold fronts reveals the pattern of change to be mediated by a thermal interaction between the oceanic and atmospheric fronts ("thermal damping and strengthening"). These results not only emphasize the significance of the GS SST gradient for storm development in the North Atlantic but also highlight the importance of resolution in assessing the role of frontal air-sea interaction in midlatitude climate variability.

  17. Regional to national constraints on US N2O emissions using atmospheric data

    NASA Astrophysics Data System (ADS)

    Miller, S. M.; Xiang, B.; Kort, E. A.; Michalak, A. M.; Wofsy, S. C.; Andrews, A. E.; Dlugokencky, E. J.

    2014-12-01

    This presentation will discuss several efforts to use atmospheric data to estimate nitrous oxide (N2O) emissions at regional to national scales across the US. In the past, N2O emissions have been difficult to quantify from atmospheric data because of the large measurement uncertainties relative to the small signal from surface sources. We overcome these challenges to estimate N2O emissions at large scale across the US agricultural belt and at regional scale over the California Central Valley using data collected from tall towers and aircraft, respectively. In general, we find N2O emissions from agriculture that exceed state and national government estimates. Furthermore, we estimate the seasonal cycle of emissions, a cycle that differs between the Great Plains and California. Finally, we will preview the results from an ongoing project to directly estimate emissions factors from fertilizer using atmospheric N2O data.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  19. 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...

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

    SciTech Connect

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

    1992-01-01

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

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

    SciTech Connect

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

    1992-09-01

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

  3. 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.

  4. Influence of volcanic eruptions on the climate of the Asian monsoon region

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  5. 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

  6. Regional atmospheric circulation over Europe during the Last Glacial Maximum and its links to precipitation

    NASA Astrophysics Data System (ADS)

    Ludwig, Patrick; Schaffernicht, Erik J.; Shao, Yaping; Pinto, Joaquim G.

    2016-03-01

    The Last Glacial Maximum (LGM) exhibits different large-scale atmospheric conditions compared to present-day climate due to altered boundary conditions. The regional atmospheric circulation and associated precipitation patterns over Europe are characterized for the first time with a weather typing approach (circulation weather types, CWT) for LGM paleoclimate simulations. The CWT approach is applied to four representative regions across Europe. While the CWTs over Western Europe are prevailing westerly for both present-day and LGM conditions, considerable differences are identified elsewhere: Southern Europe experienced more frequent westerly and cyclonic CWTs under LGM conditions, while Central and Eastern Europe was predominantly affected by southerly and easterly flow patterns. Under LGM conditions, rainfall is enhanced over Western Europe but is reduced over most of Central and Eastern Europe. These differences are explained by changing CWT frequencies and evaporation patterns over the North Atlantic Ocean. The regional differences of the CWTs and precipitation patterns are linked to the North Atlantic storm track, which was stronger over Europe in all considered models during the LGM, explaining the overall increase of the cyclonic CWT. Enhanced evaporation over the North Atlantic leads to higher moisture availability over the ocean. Despite the overall cooling during the LGM, this explains the enhanced precipitation over southwestern Europe, particularly Iberia. This study links large-scale atmospheric dynamics to the regional circulation and associated precipitation patterns and provides an improved regional assessment of the European climate under LGM conditions.

  7. 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.

  8. 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.

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

    PubMed Central

    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

  10. 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

  11. The Influence of the Extreme Ultraviolet Spectral Energy Distribution on the Structure and Composition of the Upper Atmosphere of Exoplanets

    NASA Astrophysics Data System (ADS)

    Guo, J. H.; Ben-Jaffel, Lotfi

    2016-02-01

    By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distributions (SEDs), we tested the influences of stellar EUV SEDs on the physical and chemical properties of an escaping atmosphere. We apply our model to study four exoplanets: HD 189733b, HD 209458b, GJ 436b, and Kepler-11b. We find 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 (λ), 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 Å), which pushes the transition of H/H+ to low altitudes. In contrast, the transition of H/H+ moves to higher altitudes when most photons are concentrated in the high-energy spectral region (50-400 Å). For exoplanets with a low λ, the lower temperatures of the atmosphere make many chemical reactions so important that photoionization alone can no longer determine the composition of the escaping atmosphere. For HD 189733b, it is possible to explain the time variability of Lyα between 2010 and 2011 by a change in the EUV SED of the host K-type star, yet invoking only thermal H i in the atmosphere.

  12. Role of atmospheric dynamics in controlling frequency of extreme precipitation events over the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Krichak, S. O.; Breitgand, J. S.

    2010-09-01

    Lasting long enough (from several days to months) episodes with extreme precipitation events (extreme precipitation climate events, EPCE) are quite typical for the Mediterranean region's climate. An analysis of geographical distribution of frequency of occurrence of the EPCE as well as its intraseasonal variation during the Mediterranean rainy season months is performed. Also investigated is the role of large-scale atmospheric dynamics processes over the Mediterranean region in determining the EPCE conditions over the area. An objective methodology based on earlier suggested approach by Carill et al., Clim Dyn, 2008 is adopted to determine frequencies of occurrence of extreme events in several atmospheric characteristics. Daily data on precipitation for 1960-2000 from gridded multiyear dataset National Centers for Environmental Prediction-National Center for Atmospheric Research NCAR-NCEP Reanalysis Project (NNRP) are adopted in the study. A data set with daily data on dynamic tropopause pressure and column integrated water vapor content is created. Effects of the role of atmospheric dynamics in determining occurrence of extreme precipitation events over the MR and their multiyear linear trends are analyzed. Statistically significant dependence of the ExtPrecF on those in the two tropospheric parameters is demonstrated by the patterns with spatial distributions of the DynTroPF-ExtPrecF and PrecWatF-ExtPrecF correlations. In particular, over the western part of the region (east-Atlantic, south-Europe-Mediterranean region) the EPCE's during are mainly moderated by the DynTroPF effects. Over the areas with more continental climate conditions- to the south-east and north-east of the MR (north-Africa, Arabian Peninsula, Middle East, east-Europe), the EPCE's seem to be mainly regulated by availability of extreme moisture content in the atmosphere.

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

    SciTech Connect

    Hassanein, A.; Konkashbaev, A.I.; Konkashbaev, I.K.; Nikandrov, L.B.

    1998-08-01

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

  14. 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Konda, Kohmei; Ogura, Kazuo

    2015-05-01

    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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  20. 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.

  1. 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.

  2. Regional Earth-Atmosphere Energy Balance Estimates Based on Assimilations with a GCM.

    NASA Astrophysics Data System (ADS)

    Alexander, Michael A.; Schubert, Siegfried D.

    1990-01-01

    The column budget technique described by Oort and Vonder Haar (1976) is used to assess the physical consistency and accuracy of estimates of the earth-atmosphere energy balance. Regional estimates of the atmospheric budget terms, the net radiation at the top of the atmosphere, and the time tendency and flux divergence of energy are calculated for the Special Observing Periods of the FGGE year. The data are assimilated by the Goddard Laboratory for the Atmospheres (GLA) four-dimensional analysis system. Ocean heat storage is obtained from marine temperature records while the energy flux through the surface and ocean heat flux divergence are computed as residuals.During winter the midlatitude oceans supply large quantities of energy to the overlying atmosphere which then transports the energy to the continental heat sinks, the energy flows in the opposite direction during summer. The energy exchange between continental and oceanic regions is much stronger in the Northern Hemisphere where land coverage and land-sea differences are greater.The uncertainties in the energy balance calculations are assessed by examining the errors in the observations, the data assimilation system including the GLA general circulation model, and the energy budget procedures. Sensitivity tests, error analyses and comparison with other studies indicate that the uncertainties in the continental-scale atmospheric energy flux divergence and the surface energy flux are approximately 20 W m2 and 30 W m2, respectively. We conclude that at present it is not possible to estimate accurately the ocean heat divergence and transport using the column budget technique.

  3. [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

  4. 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.

  5. Assessment of dynamical downscaling in Japan using the Regional Atmospheric Modeling System (RAMS)

    NASA Astrophysics Data System (ADS)

    Dairaku, K.; Pielke, R. A.; Beltran-Przekurat, A. B.; Iizuka, S.; Sasaki, W.

    2009-12-01

    The responses of the climate system to increases in carbon dioxide concentrations and to changes in land use/land cover and the subsequent impacts of climatic variability on humans and natural ecosystems are of fundamental concern. Because regional responses of surface hydrological and biogeochemical changes are particularly complex, it is necessary to add spatial resolution to accurately assess critical interactions within the regional climate system for climate change impacts assessments. We quantified the confidence and the uncertainties of Type II dynamical downscaling which the lateral and bottom boundary conditions were obtained from Japanese 25-year ReAnalysis (JRA-25) and assessed the value (skill) added by the downscaling to a climate simulation in Japan. We investigated the reproducibility of present climate using two regional climate models with 20 km horizontal grid spacing, the atmosphere-biosphere-river coupling regional climate model (NIED-RAMS) and the Meteorological Research Institute Nonhydrostatic Model (MRI-NHM), both of which used JRA-25 as boundary conditions. Two key variables for impact studies, surface air temperature and precipitation, were compared with the Japanese high-resolution surface observation, Automated Meteorological Data Acquisition System (AMeDAS) on 78 river basins. Results simulated by the two models were relatively in good agreement with the observation on the basin scale. The NIED-RAMS bias of 2 m air temperature (2mT) were less than 0.5K and the bias of precipitation (P) were around 10% in most of the river basins on annual averages for three years (2002-2004). The biases over 29 years shown in the long term experiment are similar to those of the three year simulation. The model could add some information as to where the larger scale information was obtained. A regional climate model often has sensitivity to model configurations, such as domain size and nudging scheme. We conducted sensitivity experiments to domain size and nudging scheme using the NIED-RAMS. Smaller domain is 128x144 and larger domain is 216x240. In each domain, we conducted experiments with/without spectral nudging scheme. Spatial characteristics of the detected bias of 2mT on river basins in Japan in the large domain were qualitatively similar to that of the small domain. The model bias of 2mT was quantitatively deteriorated in larger domain. On the other hand, model bias of P was not significantly altered in larger domain. The bias of P in June-July-August (JJA) was comparatively strongly influenced by the domain size. It can be attributed to the relatively weak synoptic-scale disturbances in the summer season. Spectral nudging scheme indicates some impacts on the mean bias of surface variables (2mT and P) particularly in JJA. But overall, the magnitudes of the impacts were not significant. It can be speculated that a large part of the domain area was dominated by the sea where sea surface temperature forcing should play a significant role, “nudging effect”, as a boundary condition.

  6. Regional US carbon sinks from three-dimensional atmospheric CO2 sampling

    PubMed Central

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

    2010-01-01

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

  7. 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.

  8. 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.

  9. Procedures for the estimation of regional scale atmospheric emissions—An example from the North West Region of England

    NASA Astrophysics Data System (ADS)

    Lindley, S. J.; Longhurst, J. W. S.; Watson, A. F. R.; Conlan, D. E.

    This paper considers the value of applying an alternative pro rata methodology to the estimation of atmospheric emissions from a given regional or local area. Such investigations into less time and resource intensive means of providing estimates in comparison to traditional methods are important due to the potential role of new methods in the development of air quality management plans. A pro rata approach is used here to estimate emissions of SO 2, NO x, CO, CO 2, VOCs and black smoke from all sources and Pb from transportation for the North West region of England. This method has the advantage of using readily available data as well as being an easily repeatable procedure which provides a good indication of emissions to be expected from a particular geographical region. This can then provide the impetus for further emission studies and ultimately a regional/local air quality management plan. Results suggest that between 1987 and 1991 trends in the emissions of the pollutants considered have been less favourable in the North West region than in the nation as a whole.

  10. Effects of Agricultural Production on Regional Variations of Atmospheric CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Corbin, K. D.; Denning, A. S.; Lokupitiya, E. Y.; Davis, K. J.; Miles, N.; Richardson, S.; Baker, I. T.; Paustian, K. H.

    2008-12-01

    The North American Carbon Program (NACP) Mid-Continent Intensive Campaign (MCI) sponsored measurements of atmospheric concentrations at five towers centered over Iowa during the summer of 2007. The towers have shown dramatic spatial gradients in CO2 over this relatively small region during 2007 and 2008. This work attempted to evaluate the cause of these gradients, and to test our coupled model's ability to reproduce these gradients. We simulated both CO2 fluxes and concentrations for June through August 2007 using the coupled ecosystem-atmosphere model SiB3-RAMS, focusing on the concentrations over the MCI region. To improve CO2 fluxes in this region, we coupled a crop phenology model to SiB3- RAMS, which calculates the leaf area index (LAI), fraction of photosynthetically active radiation absorbed by the plants (FPAR), and net ecosystem exchange (NEE) for corn, soybeans, and wheat. Including the crop model dramatically improved the concentrations at all the towers, reducing the root mean square errors by nearly half. Concentrations as low as 340 ppm were seen both in the model and in the observations. The CO2 gradient between the towers increased throughout the summer until mid-August and had considerable day-to-day variability. The model simulation suggested that large changes in the CO2 differences between the towers were due to a large-scale gradient between high concentrations to the south of the MCI region and low concentrations to the north. During the 2007 summer, the southeast United States experienced record temperatures and a severe drought. SiB3 thus simulated a large source of CO2 from the region, leading to high atmospheric CO2 concentrations in the southeast. Depending on the synoptic conditions, the large-scale gradient shifted across the MCI region, creating the large day-to-day variability seen in the differences among the towers.

  11. The Influence of Atmospheric Aerosols on Air Quality Status of the Egyptian Nile Delta

    NASA Astrophysics Data System (ADS)

    El-Askary, H. M.; Zakey, A.

    2014-12-01

    Due to the combination of natural and anthropogenic sources of emission over the Nile Delta region, the air quality status is very poor and has a significant health hazards impacts on the population. Here we focused on the optical and chemical characterizations of atmospheric aerosols in the Nile Delta using the online integrated Environmental-Climate Aerosols model (EnvClimA) during a 10 year period 2000-2010. Observations from MODIS and SeaWiFS measurements supplemented by CALIPSO and some ground-based data from AERONET, are used to validate the EnvClimA model and to illustrate the aerosol characteristics and their sources. CALIPSO measurements were used to characterize the vertical structure of aerosols and their shapes (spherical and non-spherical) for major dust storms and biomass burning events. In this study we discussed the synoptic patterns and features, which are associated with either the dust storm or high pollution events. We used MODIS derived aerosol parameters to study seasonal changes in aerosol parameters due to the influence of dust storms, anthropogenic pollution and biomass (crop residue) burning. MODIS derived deep blue AOD provided better representation of aerosol loading over north Africa (Sahara region) along with dark-target AOD and related parameters. AERONET data provided aerosol optical depth, angstrom, fine mode fraction, size fraction, volume, effective radius, refractive index, single scattering albedo, and radiative forcing during different seasons dominated by dust storms, anthropogenic pollution and biomass burning (black cloud phenomena). The results indicated that the observed AOD decreases in the summer and increases again in the fall due to agricultural burning events. Ground-based AERONET data support the "Dark Product" MODIS retrievals, as they typically show a fall peak in the 500 nm region. The number of dust distribution frequencies over Egypt has more frequency in the southeast and northwest of Egypt (5-7.5 days/year) while it decreases over Sinai Peninsula with 4-7 days/year. The meteorological data from NCEP reanalysis and the HYSPLIT model were used to identify major aerosol transport pathways over the study area. The pathways are clustered into seasonal low and high (polluted: dust or biomass or anthropogenic) aerosol days.

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

  13. 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.

  14. 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.

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

    PubMed

    Mahura, Alexander; Baklanov, Alexander

    2004-02-01

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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Atmospheric constraints on Plant Water Use Efficiency - drivers and regional patterns of change since 1900

    NASA Astrophysics Data System (ADS)

    Groenendijk, M.; Cox, P.; Lambert, F. H.; Booth, B.; Huntingford, C.

    2013-12-01

    Water Use Efficiency (WUE) defines the relationship between land-atmosphere water and carbon fluxes. With this simple mechanism, hydrological and carbon-cycle responses of vegetation to climate change can be more easily quantified. WUE increases with atmospheric carbon dioxide (CO2) concentration but also depends on changes in humidity and temperature. A positive CO2 fertilization effect can be locally constrained by humidity and temperature. By combining observed trends of these three climate variables over the 20th century regional trends in WUE can be calculated. The ecosystem WUEe is defined as a ratio of gross primary production and transpiration fluxes. On the leaf scale this is equal to the atmospheric WUEa, which is a function of the ambient and internal CO2 concentration, the saturated specific humidity (a function of temperature) and relative humidity. Using Fluxnet and CRU TS3.2 observations, and the JULES and HadCM3 models we explore the temporal and spatial variation of WUEe and WUEa, and how they respond to climate change. Leaf level definitions are valid at site level, where WUEe and WUEa simulated with JULES are equal and linearly increasing with atmospheric CO2 concentration for a range of sites. For drier sites lower values of both were simulated. The simulated values are within the same range as values derived from eddy covariance observations. Having shown the near equivalence between WUEe and WUEa for specific sites, we can use the formula for WUEa to estimate the change in global plant WUE over the 20th century, using observed climatological data and CO2 concentrations. The global average WUE increased by 25% since 1900, closely following the atmospheric CO2 concentration. But we identify large regional variation, with regions where WUE increased, but some significant regions where WUE has actually decreased during the last century. Here the CO2 fertilization effect is overtaken by an increasing offsetting temperature and related saturated specific humidity effect. In the future these drier regions will not only have to cope with a decreasing water availability but also with the related decrease in WUE, amplifying a decreasing plant carbon uptake, and if occurring in areas of agriculture, then reducing crop yield.

  1. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  3. Geographical Patterns in Cyanobacteria Distribution: Climate Influence at Regional Scale

    PubMed Central

    Pitois, Frdric; Thoraval, Isabelle; Baurs, Estelle; Thomas, Olivier

    2014-01-01

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

  4. Influence of ab initio chemistry models on simulations of the Ionian atmosphere

    NASA Astrophysics Data System (ADS)

    Parsons, Neal; Levin, Deborah A.; Walker, Andrew C.; Moore, Chris H.; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence

    2014-09-01

    There is significant scientific interest in simulating the unique atmospheric conditions on the Jovian moon Io that range from cold surface temperatures to hyperthermal interactions which possibly supply the Jovian plasma torus. The Direct Simulation Monte Carlo (DSMC) method is well suited to model the rarefied, predominantly SO2, Ionian atmosphere. High speed collisions between SO2 and the hypervelocity O atoms and ions that compose the plasma torus are a significant mechanism in determining the composition of the atmosphere; therefore, high-fidelity modeling of their interactions is crucial to the accuracy of such simulations. Typically, the Total Collision Energy (TCE) model is used to determine molecular dissociation probabilities and the Variable Hard Sphere (VHS) model is used to determine collision cross sections. However, the parameters for each of these baseline models are based on low-temperature experimental data and thus have unknown reliability for the hyperthermal conditions in the Ionian atmosphere. Recently, Molecular Dynamics/Quasi-Classical Trajectory (MD/QCT) studies have been conducted to generate accurate collision and chemistry models for the SO2-O collision pair in order to replace the baseline models. However, the influence of MD/QCT models on Ionian simulations compared to the previously used models is not well understood. In this work, 1D simulations are conducted using both the MD/QCT-based and baseline models in order to determine the effect of MD/QCT models on Ionian simulations. It is found that atmospheric structure predictions are highly sensitive to the chemistry and collision models. Specifically, the MD/QCT model predicts approximately half the SO2 atmospheric dissociation due to O and O+ bombardment compared to TCE models, and also predicts a temperature rise due to plasma heating further from the Ionian surface than the existing baseline methodologies. These findings indicate that the accurate MD/QCT chemistry and collision models provide a significant improvement over the baseline models for DSMC simulations of the Ionian atmosphere.

  5. 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.

  6. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  8. 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.

  9. Using regional-scale atmospheric δ13C 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 δ13C than do models driven by relative humidity (Ball-Berry Model). For the first time, spatial and temporal density of δ13C of CO2 atmospheric observations may be high enough to allow for regional inversions of δ13CO2 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 δ13C signature). We perform a Bayesian synthesis inversion for 1) CO2 fluxes and 2) δ13CO2 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 δ13C 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.

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

    NASA Astrophysics Data System (ADS)

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

    1994-01-01

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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. 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

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

    NASA Astrophysics Data System (ADS)

    Gratz, Lynne E.

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

  16. An Overview of the Regional Experiments for Land-Atmosphere Exchanges 2012 (Reflex 2012) Campaign

    NASA Astrophysics Data System (ADS)

    Timmermans, Wim J.; Tol, Christiaan van der; 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

    2015-12-01

    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.

  17. 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.

  18. Earth-atmosphere system and surface reflectivities in arid regions from LANDSAT multispectral scanner measurements

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Fraser, R. S.

    1976-01-01

    Programs for computing atmospheric transmission and scattering solar radiation were used to compute the ratios of the Earth-atmosphere system (space) directional reflectivities in the vertical direction to the surface reflectivity, for the four bands of the LANDSAT multispectral scanner (MSS). These ratios are presented as graphs for two water vapor levels, as a function of the surface reflectivity, for various sun elevation angles. Space directional reflectivities in the vertical direction are reported for selected arid regions in Asia, Africa and Central America from the spectral radiance levels measured by the LANDSAT MSS. From these space reflectivities, surface vertical reflectivities were computed applying the pertinent graphs. These surface reflectivities were used to estimate the surface albedo for the entire solar spectrum. The estimated albedos are in the range 0.34-0.52, higher than the values reported by most previous researchers from space measurements, but are consistent with laboratory measurements.

  19. 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.

  20. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

    NASA Astrophysics Data System (ADS)

    Mazankova, V.; Torokova, L.; Krcma, F.; Mason, N. J.; Matejcik, S.

    2016-04-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  1. Statistical analysis of the MODIS atmosphere products for the Tomsk region

    NASA Astrophysics Data System (ADS)

    Afonin, Sergey V.; Belov, Vladimir V.; Engel, Marina V.

    2005-10-01

    The paper presents the results of using the MODIS Atmosphere Products satellite information to study the atmospheric characteristics (the aerosol and water vapor) in the Tomsk Region (56-61°N, 75-90°E) in 2001-2004. The satellite data were received from the NASA Goddard Distributed Active Archive Center (DAAC) through the INTERNET.To use satellite data for a solution of scientific and applied problems, it is very important to know their accuracy. Despite the results of validation of the MODIS data have already been available in the literature, we decided to carry out additional investigations for the Tomsk Region. The paper presents the results of validation of the aerosol optical thickness (AOT) and total column precipitable water (TCPW), which are in good agreement with the test data. The statistical analysis revealed some interesting facts. Thus, for example, analyzing the data on the spatial distribution of the average seasonal values of AOT or TCPW for 2001-2003 in the Tomsk Region, we established that instead of the expected spatial homogeneity of these distributions, they have similar spatial structures.

  2. Pre-Eruption Magnetic Configurations in the Low Atmosphere of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Georgoulis, Manolis K.

    2012-07-01

    Major solar eruptions, namely flares and coronal mass ejections, rely on significant local accumulations of non-potential (free; stored in electric currents) magnetic energy and, quite likely, magnetic helicity in the solar atmosphere. Without [both of] them, eruptions cannot be powered. Simple tests can show that most free energy and helicity reside close to the lower atmospheric boundary in solar active regions, i.e. their photospheric or low chromospheric interface. Therefore, the pre-eruption configuration in this boundary should reflect these high free-energy and helicity conditions that jointly determine the degree of non-potentiality in active regions. We review the two main active-region photospheric/low-chromospheric configurations leading to major eruptions: instances of intense magnetic flux emergence in the absence of intense magnetic polarity inversion lines (PILs), and instances of strong PILs. In these configurations we discuss multiple measures that can be thought of as proxies of free magnetic energy and helicity and we outline a method to actually calculate these budgets. Combining information from different, but concerted, analyses and approaches, a new picture of eruption initiation emerges. We highlight this new insight and project on its physical plausibility and the advances that it may bring.

  3. Coupling of regional atmospheric-ocean models for climate applications in the Mediterranean basin by using CORDEX-compliant simulations

    NASA Astrophysics Data System (ADS)

    Jimenez-Guerrero, Pedro; Montávez, Juan P.; Lorente-Plazas, Raquel

    2013-04-01

    Nowadays, most regional climate models (RCMs) are essentially composed of an atmospheric component coupled to a land surface scheme and driven over ocean areas by prescribed sea surface temperature (SST). Although such a RCM can be sufficient for many applications, there are cases (like in the Mediterranean basin) in which fine scale feedbacks associated with air-sea interactions can substantially influence the spatial and temporal structure of regional climates. Therefore, in this work we present the first testing phase of the application of a coupled atmospheric-ocean regional climate model (AORCM) for the Mediterranean basin under the framework of the CORWES project. CORWES is a Spanish consortium of research groups using the Weather Research and Forecasting (WRF) model to contribute to the Coordinated Regional Climate Downscaling Experiment (CORDEX). We use WRF and ROMS models as the atmospheric and oceanic component, respectively. Coupling between WRF and ROMS is achieved in the following way: on a prescribed interval of 2 h, WRF sends wind stress, surface heat and water fluxes to ROMS time-averaged over the previous two hours. One hour later, and also with a prescribed interval of 2 h, ROMS sends time-averaged SST to WRF. Here, we mainly focus on the performance of the coupled system in reproducing the ocean surface temperatures. To separate effects of the coupling on SST, additional uncoupled atmospheric simulations are also done in parallel. The case study covers the years 2001-2005 and is described below. The resolution of the domain used is 12 km. The number of vertical levels is 30 for WRF. The ROMS domain, with 32 vertical levels, is slightly smaller than WRF innermost nest and has a higher resolution of 4 km. The lateral atmospheric boundary conditions for WRF are taken from ERA-Interim reanalysis. The lateral oceanic boundary conditions for ROMS come from the downscaling of the Simple Ocean Data Assimilation analysis (SODA) by an uncoupled nested ROMS simulation covering the Mediterranean. The atmospheric forcing for this simulation is also provided by ERA-Interim. To isolate effects of coupling on the atmosphere solutions, an atmosphere-only WRF simulation forced by ERA-Interim has been run. The results indicate that there is an overall good agreement between WRF-ROMS simulations and the E-OBS gridded dataset. During winter, the land temperature fields over most subregions in both WRF-ROMS and WRF achieve a closer agreement with E-OBS than ERAIN reanalyses, as a consequence of the dynamical downscaling. During JJA, the regional simulations exhibit a cold bias with respect to E-OBS, which is somewhat corrected by the coupled simulation. WRF-ROMS and WRF have similar average temperatures during all seasons. During summer, WRF-ROMS provides higher temperatures in the southern Mediterranean (Alboran, Benghazi, Mersa Matrouh) and lower temperatures in the Adriatic and the north-eastern Levantine basin than the atmosphere-only WRF simulations. This pattern corresponds to the prevailing anti-cyclonic oceanic structures along the southern coasts and to the cyclonic structures along the northern Mediterranean coasts, the two being separated by the Mid-Mediterranean jet. Also, 2-m summer temperatures for coupled vs. uncoupled simulations are marked by the differences in SST. WRF-ROMS and WRF-alone have similar temperature averages. Main differences are found over coastal areas (but are lower than 0.2 °C for all the Mediterranean basin). Therefore, the atmosphere-ocean coupling over this region does not significantly change the simulations of present climate 2-m temperature. Moreover, the precipitation in the WRF-ROMS and WRF simulations do not present substantial differences for total precipitation, suggesting a weak effect of air-sea feedbacks on seasonal mean precipitation over land in our modelling system. This result is somewhat expected from the well established notion that the Mediterranean area is mainly subject to large scale orographic precipitation associated to synoptic systems travelling eastward from the North Atlantic. In the WRF-ROMS coupled simulation, mostly in the warm seasons, we find less convective rainfall over the Adriatic and the north-eastern Levantine basin (more convective rainfall over southern coasts and the eastern Mediterranean) than in the atmosphere-only simulation. The differences in convective precipitation are associated to the differences found for SST in the coupled vs. uncoupled simulations. Last, we should highlight that the most important contribution of the WRF-ROMS coupled modelling is providing high-resolution oceanic components and fluxes over the area of analysis.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  5. 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.

  6. Revisiting regional flood frequency analysis in Slovakia: the region-of-influence method vs. traditional regional approaches

    NASA Astrophysics Data System (ADS)

    Gaál, Ladislav; Kohnová, Silvia; Szolgay, Ján.

    2010-05-01

    During the last 10-15 years, the Slovak hydrologists and water resources managers have been devoting considerable efforts to develop statistical tools for modelling probabilities of flood occurrence in a regional context. Initially, these models followed concepts to regional flood frequency analysis that were based on fixed regions, later the Hosking and Wallis's (HW; 1997) theory was adopted and modified. Nevertheless, it turned out to be that delineating homogeneous regions using these approaches is not a straightforward task, mostly due to the complex orography of the country. In this poster we aim at revisiting flood frequency analyses so far accomplished for Slovakia by adopting one of the pooling approaches, i.e. the region-of-influence (ROI) approach (Burn, 1990). In the ROI approach, unique pooling groups of similar sites are defined for each site under study. The similarity of sites is defined through Euclidean distance in the space of site attributes that had also proved applicability in former cluster analyses: catchment area, afforested area, hydrogeological catchment index and the mean annual precipitation. The homogeneity of the proposed pooling groups is evaluated by the built-in homogeneity test by Lu and Stedinger (1992). Two alternatives of the ROI approach are examined: in the first one the target size of the pooling groups is adjusted to the target return period T of the estimated flood quantiles, while in the other one, the target size is fixed, regardless of the target T. The statistical models of the ROI approach are inter-compared by the conventional regionalization approach based on the HW methodology where the parameters of flood frequency distributions were derived by means of L-moment statistics and a regional formula for the estimation of the index flood was derived by multiple regression methods using physiographic and climatic catchment characteristics. The inter-comparison of different frequency models is evaluated by means of the root mean square error of data from Monte Carlo simulations. The analysis is based on the annual peak discharges from 168 small and mid-sized catchments from Slovakia. The study is supported by the Grant Agency of AS CR under project B300420801; the Slovak Research and Development Agency under the contract No. APVV-0443-07 and the Slovak VEGA Grant Agency under the project No. 1/0103/10. Burn, D.H., 1990: Evaluation of regional flood frequency analysis with a region of influence approach. Water Resources Research, 26(10), 2257-2265. Hosking, J.R.M., Wallis, J.R., 1997: Regional frequency analysis: an approach based on L-moments. Cambridge University Press, Cambridge. Lu, L.-H., Stedinger, J.R., 1992: Sampling variance of normalized GEV/PWM quantile estimators and a regional homogeneity test. Journal of Hydrology, 138(1-2), 223-245.

  7. 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.

  8. Influence of modified atmosphere and preservatives on the growth of Zygosaccharomyces rouxii isolated from dried fruits.

    PubMed

    el Halouat, A; Debevere, J M

    1996-12-01

    The influence of water activity (alpha w), preservatives, modified atmosphere and their combinations on the growth of Z. rouxii was determined by cultivating two strains isolated from raisins and prunes in culture media under different conditions and by counting the colony forming units. Yeast extract glucose broths or agars were adjusted to the desired alpha w by means of glucose. Preservatives added to the media (0-600 ppm) were either K-sorbate, Na-benzoate or their mixture. Modified atmospheres were carried out by packing culture plates or flasks in plastic bags under different CO2-N2 gas mixture. Response surface design was carried out to optimize the growth inhibition of Z. rouxii by the mentioned factors. Although Z. rouxii is osmotolerant, the strains studied could not grow at alpha w 0.79. They also showed a high tolerance to CO2; even 80% CO2 seems to not inhibit growth. However, CO2 atmosphere at high pHs and low preservative concentrations stimulated yeast growth. At pH 4.0 and under modified atmosphere (80% CO2-20% N2), no growth was observed at any alpha w in the range of 0.80-0.90 when using a preservative concentration of 220 ppm Ksorbate or 280 ppm Na-benzoate. PMID:8930707

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

    SciTech Connect

    Michalakes, J.G.

    1997-08-01

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

  10. Complex topography influences atmospheric nitrate deposition in a neotropical mountain rainforest

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  11. Chemistry-turbulence interactions and mesoscale variability influence the cleansing efficiency of the atmosphere

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Karl, T.; Yuan, B.; Mauldin, R. L.; Cantrell, C. A.; Guenther, A. B.; Patton, E. G.; Weinheimer, A. J.; Knote, C.; Orlando, J.; Emmons, L.; Apel, E.; Hornbrook, R.; Shertz, S.; Ullmann, K.; Hall, S.; Graus, M.; Gouw, J.; Zhou, X.; Ye, C.

    2015-12-01

    The hydroxyl radical (OH) is the most important oxidant in the atmosphere and the primary sink for isoprene, the dominant volatile organic compound emitted by vegetation. Recent research on the atmospheric oxidation capacity in isoprene-dominated environments has suggested missing radical sources leading to significant overestimation of the lifetime of isoprene. Here we report, for the first time, a comprehensive experimental budget of isoprene in the planetary boundary layer based on airborne flux measurements along with in situ OH observations in the Southeast and Central U.S. Our findings show that surface heterogeneity of isoprene emissions lead to a physical separation of isoprene and OH resulting in an effective slowdown in the chemistry. Depending on surface heterogeneity, the intensity of segregation (Is) could locally slow down isoprene chemistry up to 30%. The effect of segregated reactants in the planetary boundary layer on average has an influence on modeled OH radicals that is comparable to that of recently proposed radical recycling mechanisms.

  12. 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...

  13. 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.

  14. Surface-Atmosphere Moisture Interactions in the Frozen Ground Regions of Eurasia.

    PubMed

    Ford, Trent W; Frauenfeld, Oliver W

    2016-01-01

    Climate models simulate an intensifying Arctic hydrologic cycle in response to climatic warming, however the role of surface-atmosphere interactions from degrading frozen ground is unclear in these projections. Using Modern-Era Retrospective Analysis for Research and Applications (MERRA) data in high-latitude Eurasia, we examine long-term variability in surface-atmosphere coupling as represented by the statistical relationship between surface evaporative fraction (EF) and afternoon precipitation. Changes in EF, precipitation, and their statistical association are then related to underlying permafrost type and snow cover. Results indicate significant positive trends in July EF in the Central Siberian Plateau, corresponding to significant increases in afternoon precipitation. The positive trends are only significant over continuous permafrost, with non-significant or negative EF and precipitation trends over isolated, sporadic, and discontinuous permafrost areas. Concurrently, increasing EF and subsequent precipitation are found to coincide with significant trends in May and June snowmelt, which potentially provides the moisture source for the observed enhanced latent heating and moisture recycling in the region. As climate change causes continuous permafrost to transition to discontinuous, discontinuous to sporadic, sporadic to isolated, and isolated permafrost disappears, this will also alter patterns of atmospheric convection, moisture recycling, and hence the hydrologic cycle in high-latitude land areas. PMID:26777288

  15. Surface–Atmosphere Moisture Interactions in the Frozen Ground Regions of Eurasia

    PubMed Central

    Ford, Trent W.; Frauenfeld, Oliver W.

    2016-01-01

    Climate models simulate an intensifying Arctic hydrologic cycle in response to climatic warming, however the role of surface-atmosphere interactions from degrading frozen ground is unclear in these projections. Using Modern-Era Retrospective Analysis for Research and Applications (MERRA) data in high-latitude Eurasia, we examine long-term variability in surface-atmosphere coupling as represented by the statistical relationship between surface evaporative fraction (EF) and afternoon precipitation. Changes in EF, precipitation, and their statistical association are then related to underlying permafrost type and snow cover. Results indicate significant positive trends in July EF in the Central Siberian Plateau, corresponding to significant increases in afternoon precipitation. The positive trends are only significant over continuous permafrost, with non-significant or negative EF and precipitation trends over isolated, sporadic, and discontinuous permafrost areas. Concurrently, increasing EF and subsequent precipitation are found to coincide with significant trends in May and June snowmelt, which potentially provides the moisture source for the observed enhanced latent heating and moisture recycling in the region. As climate change causes continuous permafrost to transition to discontinuous, discontinuous to sporadic, sporadic to isolated, and isolated permafrost disappears, this will also alter patterns of atmospheric convection, moisture recycling, and hence the hydrologic cycle in high-latitude land areas. PMID:26777288

  16. Atmospheric moisture transport over the Southern Ocean: interannual, seasonal and regional variability and change

    NASA Astrophysics Data System (ADS)

    Tsukernik, M.; Lynch, A. H.

    2011-12-01

    The Antarctic ice sheet constitutes the largest freshwater reservoir on Earth and is the biggest potential contributor to future changes in global sea level. According to recent studies, the Antarctic icesheet, especially the western part has been losing mass at an accelerated rate. Meanwhile, the sea ice extent in the Southern Ocean has been increasing. Sea ice changes, however, reveal spatial inconsistencies in trends across Antarctic coastal seas. In this study we focus on the atmospheric meridional moisture transport across the Southern Ocean - a key variable for precipitation, ice sheet growth and an important factor in sea ice development. We show that the transient eddies play a crucial role in the Antarctic/Southern Ocean atmospheric moisture transport. These features constitute themselves in cyclones and polar (meso-scale) lows and are responsible for 80% or more of total meridional moisture transport. We employ ERA-Interim dataset for 1989-present to assess the seasonal variability and trends of the atmospheric moisture transport, particularly focusing on the synoptic and meso-scale features. We also examine key regions separately to assess the difference in moisture transport over the Antarctic coastal seas and evaluate its role in sea ice formation. We compare our results to those from other reanalysis and available satellite data. We emphasize that high-resolution data is key for understanding recently observed trends and variability in Antarctic climate characteristics.

  17. Surface-Atmosphere Moisture Interactions in the Frozen Ground Regions of Eurasia

    NASA Astrophysics Data System (ADS)

    Ford, Trent W.; Frauenfeld, Oliver W.

    2016-01-01

    Climate models simulate an intensifying Arctic hydrologic cycle in response to climatic warming, however the role of surface-atmosphere interactions from degrading frozen ground is unclear in these projections. Using Modern-Era Retrospective Analysis for Research and Applications (MERRA) data in high-latitude Eurasia, we examine long-term variability in surface-atmosphere coupling as represented by the statistical relationship between surface evaporative fraction (EF) and afternoon precipitation. Changes in EF, precipitation, and their statistical association are then related to underlying permafrost type and snow cover. Results indicate significant positive trends in July EF in the Central Siberian Plateau, corresponding to significant increases in afternoon precipitation. The positive trends are only significant over continuous permafrost, with non-significant or negative EF and precipitation trends over isolated, sporadic, and discontinuous permafrost areas. Concurrently, increasing EF and subsequent precipitation are found to coincide with significant trends in May and June snowmelt, which potentially provides the moisture source for the observed enhanced latent heating and moisture recycling in the region. As climate change causes continuous permafrost to transition to discontinuous, discontinuous to sporadic, sporadic to isolated, and isolated permafrost disappears, this will also alter patterns of atmospheric convection, moisture recycling, and hence the hydrologic cycle in high-latitude land areas.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Stable isotopes of the water vapor represent a powerful tool for tracing atmospheric vapor origin and mixing processes. Laser spectrometry recently allowed high time resolution measurements, but despite an increasing number of experimental studies, there is still a need for a better understanding of the main drivers of isotopic signal variability at different time scales. We present results of in situ measurements of δ18O and δD during 36 consecutive days in summer 2011 in atmospheric vapor of a Mediterranean coastal wetland exposed to high evapotranspiration (Camargue, Rhône River delta, France). A calibration protocol was tested and instrument stability was analysed over the period. The mean composition of atmospheric vapor during the campaign is δ18O = -14.66‰ and δD = -95.4‰, with δv data plotting clearly above the local meteoric water line, and an average deuterium excess (dv) of 21.9‰. At daily time step, we show a clear separation of isotopic characteristics with respect to the air mass back trajectories, with the Northern air masses providing depleted compositions (δ18O = -15.83‰, δD = -103.5‰) compared to Mediterranean air masses (δ18O = -13.13‰, δD = -86.5‰). There is also a clear separation between dv corresponding to these different air mass origins, but not in the same direction as was previously evidenced from regional rainfall data, with higher dv found for Northern air masses (23.2‰) than for Mediterranean air masses (18.6‰). Based on twenty-four average hourly data, we propose a depiction of typical daily evolution of water vapor isotopic composition. High diurnal variations in dv is attributed to a dominant control of evapotranspiration, over entrainment of free atmosphere. Daily cycles in dv are more pronounced for Mediterranean than for North Atlantic air mass origin and are discussed in terms of local evapotranspiration versus regional signatures. We calculate the composition of the vapor source that produces the day-time increase in dv for the different air mass origins, and propose an atmospheric water and isotopic mass balance.

  19. 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.

  20. 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

  1. 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.

  2. Influence of Surface Seawater and Atmospheric Conditions on the Ccn Activity of Ocean-Derived Aerosol

    NASA Astrophysics Data System (ADS)

    Quinn, P.; Bates, T. S.; Russell, L. M.; Frossard, A. A.; Keene, W. C.; Kieber, D. J.; Hakala, J. P.

    2012-12-01

    Ocean-derived aerosols are produced from direct injection into the atmosphere (primary production) and gas-to-particle conversion in the atmosphere (secondary production). These different production mechanisms result in a broad range of particle sizes that has implications for the impact of ocean-derived aerosol on climate. The chemical composition of ocean-derived aerosols is a result of a complex mixture of inorganic sea salt and organic matter including polysaccharides, proteins, amino acids, microorganisms and their fragments, and secondary oxidation products. Both production mechanisms and biological processes in the surface ocean impact the ability of ocean-derived aerosol to act as cloud condensation nuclei (CCN). In addition, CCN activity can be impacted by atmospheric processing that modifies particle size and composition after the aerosol is emitted from the ocean. To understand relationships between production mechanism, surface ocean biology, and atmospheric processing, measurements were made of surface ocean chlorophyll and dissolved organic matter; nascent sea spray aerosol freshly emitted from the ocean surface; and ambient marine aerosol. These measurements were made along the coast of California and in the North Atlantic between the northeast US and Bermuda. These regions include both eutrophic and oligotraphic waters and, thus, provide for observations over a wide range of ocean conditions.

  3. Evidence of the observed change in the atmosphere-ocean interactions over the South China Sea during summer in a regional climate model

    NASA Astrophysics Data System (ADS)

    Jang, Hye-Yeong; Yeh, Sang-Wook; Chang, Eun-Chul; Kim, Baek-Min

    2016-01-01

    The South China Sea plays a key role to change the precipitation variability in East Asia by influencing the northward moisture transport. Previous study found that there exist changes in atmosphere-ocean interactions over the South China Sea (SCS) before and after the late 1990s during boreal summer (June-July-August) in the observations. This study further supports such changes using two simulations of the atmospheric regional climate model (RCM) forced by historical sea surface temperature (SST). The control run is forced by historical SSTs, which are prescribed in the entire domain in the RCM. In addition to the control run, an additional idealized experiment is conducted, i.e., the historical SSTs are prescribed in the SCS only and the climatological SST is prescribed outside the SCS to examine the changes in the atmosphere-ocean interactions in the SCS. It is found that the simultaneous correlation coefficient between SST and precipitation changes significantly over the SCS before and after the late 1990s. This result supports the notion that there are significant changes in atmosphere-ocean interactions over the SCS before and after the late 1990, which affects the ability of the RCM to simulate precipitation variability accurately relative to observation. This result implies that the simulations of atmospheric circulation model results forced by observed SST before the late 1990 should be cautiously interpreted because the observed SST anomalies are forced by the atmosphere.

  4. 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 δ15N-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. δ15N-NH4 values varied from -6.3 to +14.8‰ with the highest δ15N values typically associated with elevated NH4-N deposition rates. δ15N-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 δ15N values providing a potential tracer. Applying a two-end-member mixing analysis using a background δ15N-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.

  5. 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.

  6. 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.

  7. A Unified Data Assimilation Strategy for Regional Coupled Atmosphere-Ocean Prediction Systems

    NASA Astrophysics Data System (ADS)

    Xie, Lian; Liu, Bin; Zhang, Fuqing; Weng, Yonghui

    2014-05-01

    Improving tropical cyclone (TC) forecasts is a top priority in weather forecasting. Assimilating various observational data to produce better initial conditions for numerical models using advanced data assimilation techniques has been shown to benefit TC intensity forecasts, whereas assimilating large-scale environmental circulation into regional models by spectral nudging or Scale-Selective Data Assimilation (SSDA) has been demonstrated to improve TC track forecasts. Meanwhile, taking into account various air-sea interaction processes by high-resolution coupled air-sea modelling systems has also been shown to improve TC intensity forecasts. Despite the advances in data assimilation and air-sea coupled models, large errors in TC intensity and track forecasting remain. For example, Hurricane Nate (2011) has brought considerable challenge for the TC operational forecasting community, with very large intensity forecast errors (27, 25, and 40 kts for 48, 72, and 96 h, respectively) for the official forecasts. Considering the slow-moving nature of Hurricane Nate, it is reasonable to hypothesize that air-sea interaction processes played a critical role in the intensity change of the storm, and accurate representation of the upper ocean dynamics and thermodynamics is necessary to quantitatively describe the air-sea interaction processes. Currently, data assimilation techniques are generally only applied to hurricane forecasting in stand-alone atmospheric or oceanic model. In fact, most of the regional hurricane forecasting models only included data assimilation techniques for improving the initial condition of the atmospheric model. In such a situation, the benefit of adjustments in one model (atmospheric or oceanic) by assimilating observational data can be compromised by errors from the other model. Thus, unified data assimilation techniques for coupled air-sea modelling systems, which not only simultaneously assimilate atmospheric and oceanic observations into the coupled air-sea modelling system, but also nudging the large-scale environmental flow in the regional model towards global model forecasts are of increasing necessity. In this presentation, we will outline a strategy for an integrated approach in air-sea coupled data assimilation and discuss its benefits and feasibility from incremental results for select historical hurricane cases.

  8. 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 γ-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.

  9. 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.

  10. Contribution of regional sources to atmospheric methane over the Amazon Basin in 2010 and 2011

    NASA Astrophysics Data System (ADS)

    Wilson, Chris; Gloor, Manuel; Gatti, Luciana V.; Miller, John B.; Monks, Sarah A.; McNorton, Joey; Bloom, A. Anthony; Basso, Luana S.; Chipperfield, Martyn P.

    2016-03-01

    We present an assessment of methane (CH4) atmospheric concentrations over the Amazon Basin for 2010 and 2011 using a 3-D atmospheric chemical transport model, two wetland emission models, and new observations made during biweekly flights made over four locations within the basin. We attempt to constrain basin-wide CH4 emissions using the observations, and since 2010 was an unusually dry year, we assess the effect of this drought on Amazonian methane emissions. We find that South American emissions contribute up to 150 ppb to concentrations at the sites, mainly originating from within the basin. Our atmospheric model simulations agree reasonably well with measurements at three of the locations (0.28 ≤ r2 ≤ 0.63, mean bias ≤ 9.5 ppb). Attempts to improve the simulated background CH4 concentration through analysis of simulated and observed sulphur hexafluoride concentrations do not improve the model performance, however. Through minimisation of seasonal biases between the simulated and observed atmospheric concentrations, we scale our prior emission inventories to derive total basin-wide methane emissions of 36.5-41.1 Tg(CH4)/yr in 2010 and 31.6-38.8 Tg(CH4)/yr in 2011. These totals suggest that the Amazon contributes significantly (up to 7%) to global CH4 emissions. Our analysis indicates that factors other than precipitation, such as temperature variations or tree mortality, may have affected microbial emission rates. However, given the uncertainty of our emission estimates, we cannot say definitively whether the noncombustion emissions from the region were different in 2010 and 2011, despite contrasting meteorological conditions between the two years.

  11. Sources of atmospheric acidity in an agricultural-industrial region of So Paulo State, Brazil

    NASA Astrophysics Data System (ADS)

    Da Rocha, G. O.; Franco, A.; Allen, A. G.; Cardoso, A. A.

    2003-04-01

    Surface-based measurements of atmospheric formic acid (HCOOH), acetic acid (CH3COOH), sulfur dioxide (SO2), hydrogen chloride (HCl), and nitric acid (HNO3) were made in central So Paulo State, Brazil, between April 1999 and March 2000. Mean concentrations were 9.0 ppb (HCOOH), 1.3 ppb (CH3COOH), 4.9 ppb (SO2), 0.3 ppb (HCl), and 0.5 ppb (HNO3). Concentrations in sugar cane burning plumes were 1160-4230 ppb (HCOOH), 360-1750 ppb (CH3COOH), 10-630 ppb (SO2), 4-210 ppb (HCl), and 14-90 ppb (HNO3). Higher ambient concentrations of SO2, HCl and HNO3 were measured during the burning season (May-November). Concentrations of SO2 and HCl increased during the evening, and of HCOOH and CH3COOH were lowest in the morning, with peak levels in the afternoon. Ratios obtained between different species showed either nighttime maxima (SO2/HCOOH, SO2/CH3COOH, SO2/HNO3, CH3COOH/HNO3, SO2/HCl and HCOOH/HNO3), daytime maxima (HCOOH/HCl, CH3COOH/HCl and HNO3/HCl), or no clear trends (HCOOH/CH3COOH). Correlation analysis showed that SO2 and HCl were primary emissions from biomass burning and road transport; HCOOH, HNO3 and CH3COOH were products of photochemistry; HCOOH and CH3COOH were emitted directly during combustion as well as from biogenic sources. Biomass burning affected atmospheric acidity on a regional scale, while vehicular emissions had greater impact in urban and adjacent areas. Atmospheric ammonia levels were insufficient to neutralize atmospheric acidity, which was mainly removed by deposition to the surface.

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Tim, Nele; Zorita, Eduardo; Hünicke, Birgit

    2014-05-01

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

  15. Dynamical Downscaling NCEP Global Climate Forecast System (CFS) Seasonal Predictions Using Regional Atmospheric Modeling System (RAMS)

    NASA Astrophysics Data System (ADS)

    Lu, L.; Zheng, Y.; Pielke, R. A.

    2009-12-01

    As part of the NOAA CPPA-sponsored MRED project, the state-of-the-art Regional Atmospheric Modeling System (RAMS) version 6.0 is used to dynamically and progressively downscale NCEP global Climate Forecast System (CFS, at 100s-km grid increment) seasonal predictions to a regional domain that covers the conterminous United States at 30-km grid increment. The first set of RCM prediction experiment focuses on the winter seasons, during which the precipitation is largely dependent on synoptic-scale mid-latitude storms and orographic dominant mesoscale processes. Our first suite of numerical experiment includes one ensemble member for each year from 1982 through 2008, with all the simulations starting on December 1 and ending on April 30. Driven by the same atmospheric and SST forcings, RAMS will be compared with other RCMs, and evaluated against observations and reanalysis (NARR) to see if the simulations capture the climatology and interannual variability of temperature and precipitation distributions. The overall strengths and weaknesses of the modeling systems will be identified, as well as the consistent model biases. In addition, we will analyze the changes in kinetic energy spectra before and after the spectral nudging algorithm is implemented. The results show that with the spectral nudging scheme, RAMS can better preserve large-scale kinetic energy than standard boundary forcing method, and allow more large-scale energy to cascade to smaller scales.

  16. Projected changes in atmospheric river events in Arizona as simulated by global and regional climate models

    NASA Astrophysics Data System (ADS)

    Rivera, Erick R.; Dominguez, Francina

    2015-12-01

    Inland-penetrating atmospheric rivers (ARs) affect the United States Southwest and significantly contribute to cool season precipitation. In this study, we examine the results from an ensemble of dynamically downscaled simulations from the North American Regional Climate Change Assessment Program (NARCCAP) and their driving general circulation models (GCMs) in order to determine statistically significant changes in the intensity of the cool season ARs impacting Arizona and the associated precipitation. Future greenhouse gas emissions follow the A2 emission scenario from the Intergovernmental Panel on Climate Change Fourth Assessment Report simulations. We find that there is a consistent and clear intensification of the AR-related water vapor transport in both the global and regional simulations which reflects the increase in water vapor content due to warmer atmospheric temperatures, according to the Clausius-Clapeyron relationship. However, the response of AR-related precipitation intensity to increased moisture flux and column-integrated water vapor is weak and no significant changes are projected either by the GCMs or the NARCCAP models. This lack of robust precipitation variations can be explained in part by the absence of meaningful changes in both the large-scale water vapor flux convergence and the maximum positive relative vorticity in the GCMs. Additionally, some global models show a robust decrease in relative humidity which may also be responsible for the projected precipitation patterns.

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

    NASA Astrophysics Data System (ADS)

    Ghanbari, Reza Namdar; Bravo, Hector R.

    2008-10-01

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

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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 preëminence of the SON season suggests that a seasonally lagged relationship between the Indian monsoon and Indian Ocean Walker circulation influences IPWP hydroclimatic variability during the Holocene.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Nitrogen oxide and sulfur oxide emission from ongoing development of oil sands in northern Alberta results in regionally elevated atmospheric deposition of N and S in an area where background deposition of both N and S is exceptionally low (less than 1 kg/ha/yr). Because bogs, which represent major landforms in the Alberta oil sands region, are believed to be N-limited and potentially sensitive to S inputs, we have been investigating the effects of elevated N deposition on C, N, and S cycling in bogs, as well as the potential of bogs to serve as monitors of N and S deposition. Toward this latter end, we have measured seasonal variation (5 sampling dates between June and October 2009) concentrations of N and S, as well as δ15N value, in leaf tissues (Picea mariana (ectomycorrhizal); Ledum groenlandicum, Oxycoccos microcarpon, Vaccinium vitis-idaea (ericoid mycorrhizal); Rubus chamaemorus, and Smilacina trifolia (nonmycorrhizal), Sphagnum (S. fuscum, S. capillifolium, S. magellanicum, S. angustifolium) moss capitula (top 1-cm of plant) and lichens (Cladina mitis and Evernia mesomorpha) at 5 bogs at distances ranging from 14 to 300 km from the heart of the oil sands mining area. Averaged across all sites and sampling dates, N concentrations in ectomycorrhizal, ericoid mycorrhizal, nonmycorrhizal, Sphagnum, and lichens was 8.6 + 0.2, 11.9 + 0.2, 26.3 + 0.6, 10.2 + 0.1, 7.2 + 0.2 mg/g, respectively; δ15N values were -10.3 + 0.1, -6.0 + 0.1, 1.7 + 0.2, -5.3 + 0.1, -4.7 + 0.1 mg/g, respectively, and S concentrations were 1.07 + 0.2, 1.31 + 0.2, 1.94 + 0.6, 1.46 + 0.2, 1.11 + 0.3 mg/g, respectively. Plant functional groups and individual species behaved differently with respect to both seasonal variation and site differences, often with significant interactions when analyzed using two-way analyses of variance. Some species exhibited seasonal variation in some aspects of plant tissue chemistry, while others did not; when a species did exhibit seasonal variation, the variation was rather consistent between sites. More importantly, however, canonical discriminant analysis (with potential variables of C, N, or S concentrations, C:N, C:S, or N:S ratios, and δ15N values) indicated that the five sites can be differentiated based on plant tissue chemistry, most clearly separating the site closest and the site farthest from the oil sands mining area. The first canonical axis explained between 66 and 91 percent of the overall variation, but the variables that were significantly correlated with the first canonical axis differed between species. We conclude that plant tissue chemistry exhibited a significant variation between plant functional groups, between species, between sites, and seasonally. Some of this variation appears to be related to distance from the heart of oil sands mining activity in northern Alberta, possibly reflecting regionally elevated atmospheric deposition of N and S. Bog plants, through analysis of tissue chemistry, have the potential to serve as biomonitors of the anticipated spread of elevated atmospheric N and S deposition as oil sands development continues to grow in northern Alberta.

  4. Flood Frequency of Unregulated Streams of Tennessee Using Regional-Regression Equations and the Region-of-Influence Method

    USGS Publications Warehouse

    Law, G.S.; Tasker, Gary D.

    2003-01-01

    The region-of-influence method and regional-regression equations are used to predict flood frequency of unregulated and ungaged rivers and streams of Tennessee. The prediction methods have been developed using strem-gage records from unregulated streams draining basins having 1-30% total impervious area. A computer application automates the calculation of the flood frequencies of the unregulated streams. Average deleted-residual prediction errors for the region-of-influence method are found to be slightly smaller than those for the regional regression methods.

  5. Decadal trends of ocean and land carbon fluxes from a regional joint ocean-atmosphere inversion

    NASA Astrophysics Data System (ADS)

    Steinkamp, K.; Gruber, N.

    2015-12-01

    From 1980 until 2010, the combined CO2 sink strengths of ocean and land increased by nearly 50% (-0.55 Pg C yr-1 decade-1), but the spatial distribution of this trend is not well known. We address this by performing a joint cyclostationary ocean-atmosphere inversion for the three decades 1980-1989, 1990-1999, and 2000-2008, using only carbon data from the ocean and atmosphere as constraints, i.e., without applying any prior information about the land fluxes. We find that in the inversion, most of the 30 year sink trend stems from the ocean (-0.44 Pg C yr-1 decade-1). The contribution of the terrestrial biosphere is commensurably smaller but has more decadal variability. First, the land sink strength intensified in the 1990s by 0.4 (±0.3) Pg C yr-1 compared to the 1980s but then weakened slightly by 0.2 (±0.4) Pg C yr-1 in the 2000s. The different land regions contributed very variedly to these global trends. While the northern extratropical land acted as an increasing carbon sink throughout the examined period primarily driven by boreal regions, the tropical land is estimated to have acted as an increasing source of CO2, with source magnitude and trend dominated by enhanced release in tropical America during the Amazon mean wet season. This pattern is largely unchanged if the oceanic inversion constraint, which is based on a stationary ocean circulation, is replaced by an estimate based on simulation results from an ocean biogeochemical general circulation model that includes year-to-year variability in the air-sea CO2 fluxes and also has a trend (-0.07 Pg C yr-1 decade-1) that is at the very low end of current estimates. However, the land/ocean partitioning of the trend contribution is adjusted accordingly. Oceanic carbon data has a major impact on carbon exchange for all tropical regions and southern Africa but also for observationally better constrained regions in North America and temperate Asia. The European trend exhibits a strong sensitivity to the choice of the atmospheric CO2 network.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  9. Determination of regional evapotranspiration from measurements of the atmospheric boundary layer. Final report

    SciTech Connect

    Hipps, L.E.; Swiatek, E.

    1993-01-01

    Many surface flux experiments have been conducted at local scales over irrigated and nonirrigated agricultural fields, and over forests. These experiments have collected a vast amount of information on the microclimate, hydrological cycle, and energy balance for these areas. The information is used to make groundwater recharge estimates from which irrigation schedules and general water management practices are developed. The focus of the research is to study the local and regional values of sensible and latent heat flux in a closed desert basin typical of the Great Basin. The local scale fluxes were found by several eddy correlation stations located throughout the study site. Net radiation and soil heat flux were also measured at one site. Temporal and spatial variability in the local scale sensible and latent heat fluxes were examined. The surface fluxes were averaged to give regional flux estimates. The regional surface flux estimate was then used as the ground truth for the regional scale estimates made by the Atmospheric Boundary Layer (ABL) approaches.

  10. 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.

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

    EPA Science Inventory

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

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  15. The multiyear surface climatology of a regional atmospheric model over the western United States

    SciTech Connect

    Giorgi, F.; Bates, G.T.; Nieman, S.J. )

    1993-01-01

    This paper presents a validation analysis of the climatology of a version of the National Center for Atmospheric Research-Pennsylvania State University limited-area model (MM4) developed for application to regional climate simulation over the western United States. Two continuous multiyear simulations, for the periods 1 January 1982-31 December 1983 and 1 January 1988-25 April 1989, were performed over this region with the MM4 driven by ECMWF analyses of observations and run at a horizontal resolution of 60 km. The model used includes horizontal diffusion on terrain-following [sigma] coordinates, a Kuo-type cumulus parameterization, sophisticated radiative transfer and surface physics-soil hydrology packages, and a relaxation boundary-conditions procedure. Model-produced surface air temperatures, precipitation, and snow depths were compared with observations from about 390 stations distributed throughout the western United States. The base-model run reproduced the seasonal cycle of temperature and precipitation well. The effects of topography on the regional distribution of precipitation were well reproduced. When regionally averaged, absolute model-precipitation biases were mostly in the range of 10%-50% of observations. The model generally simulated precipitation better in the cold season than in the warm season, and over coastal regions than in the continental interior. The simulated seasonal cycles of snowpack formation and melting were realistic. Over the Rocky Mountain regions the model reproduced wintertime precipitation amounts well but over-predicted summertime precipitation. However, modifications were found to provide an improved simulation of summer precipitation while not substantially altering wintertime precipitation. This work shows that it is feasible to apply current limited-area models to climate studies. 30 refs., 12 figs., 5 tabs.

  16. Elemental Compositions of the Martian Surface and Atmosphere and Their Influence on Future Mars Science

    NASA Astrophysics Data System (ADS)

    Boynton, W. V.; Taylor, J.; McLennan, S. M.; Sprague, A. L.; Newsom, H. E.

    2009-12-01

    Landing site selection for future missions, including sample return missions, requires a complete understanding both of the detailed local geology and the regional geological, geophysical, and geochemical context. Orbital imaging and spectroscopic instruments provide essential data about physical properties, local geology, and mineralogy, but only the Mars Odyssey Gamma-Ray Spectrometer (GRS) provides geochemical context by mapping the composition of the Martian near-surface environment. The GRS has provided elemental concentration maps of Mars from approximately 52○ south to 52○ north. Elements for which maps are available are K, Th, Si, Fe, Ca, Cl, and H, with S and Al in preparation. This is an excellent mix of incompatible elements (K, Th), major elements (Si, Fe, Ca, Al), and elements affected by aqueous processes (H, Cl, S). These data provide information on Martian bulk composition, crust formation and evolution, the composition of the dominant types of igneous rocks, and the intensity of aqueous alteration events. The data show that the surface composition is not uniform even in areas that are heavily mantled in surficial materials, thus arguing against surficial mantling materials originating from a globally homogenized dust component. The implication of this result is that the surficial materials are locally derived and represent the chemical characteristics of the surface rocks. The global K/Th ratio is consistent with previous estimates of Martian bulk composition, a critical component in testing models for planetary accretion. Its relatively narrow range (95% of the surface has K/Th between 4000 and 7000) indicates that aqueous alteration of the surface occurred in short duration events that did not fractionate K from Th. Basalts and sediments derived from basalts make up most of the Martian crust. These observations contribute to addressing fundamental problems in planetary and specifically Martian science, including the evolution of the Martian crust and mantle, planetary accretion, and the role of water on the Martian surface, and emphasize the need for continued direct chemical measurements of the surface, perhaps using orbital elemental measurements as guides for site selection. The GRS gamma-ray data have had a significant and unexpected impact on Mars atmospheric science and general circulation models used to predict Mars’ atmospheric dynamics. We found that Ar is enriched over the winter poles due to the transport of atmosphere into the polar region to replenish the CO2 condensed out of the atmosphere to form the seasonal cap. In the case of the south pole, the enrichment is a factor of six, but surprisingly around LS = 90○, even as the cap is continuing to grow, the Ar diffuses out of the polar region. These data show the value of long-term atmospheric monitoring from orbit.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  18. Influence of land-atmosphere feedbacks on temperature and precipitation extremes in the GLACE-CMIP5 ensemble

    NASA Astrophysics Data System (ADS)

    Lorenz, Ruth; Argüeso, Daniel; Donat, Markus G.; Pitman, Andrew J.; Hurk, Bart; Berg, Alexis; Lawrence, David M.; Chéruy, Frédérique; Ducharne, Agnès.; Hagemann, Stefan; Meier, Arndt; Milly, P. C. D.; Seneviratne, Sonia I.

    2016-01-01

    We examine how soil moisture variability and trends affect the simulation of temperature and precipitation extremes in six global climate models using the experimental protocol of the Global Land-Atmosphere Coupling Experiment of the Coupled Model Intercomparison Project, Phase 5 (GLACE-CMIP5). This protocol enables separate examinations of the influences of soil moisture variability and trends on the intensity, frequency, and duration of climate extremes by the end of the 21st century under a business-as-usual (Representative Concentration Pathway 8.5) emission scenario. Removing soil moisture variability significantly reduces temperature extremes over most continental surfaces, while wet precipitation extremes are enhanced in the tropics. Projected drying trends in soil moisture lead to increases in intensity, frequency, and duration of temperature extremes by the end of the 21st century. Wet precipitation extremes are decreased in the tropics with soil moisture trends in the simulations, while dry extremes are enhanced in some regions, in particular the Mediterranean and Australia. However, the ensemble results mask considerable differences in the soil moisture trends simulated by the six climate models. We find that the large differences between the models in soil moisture trends, which are related to an unknown combination of differences in atmospheric forcing (precipitation, net radiation), flux partitioning at the land surface, and how soil moisture is parameterized, imply considerable uncertainty in future changes in climate extremes.

  19. 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.

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

    PubMed

    Wang, Menghua; Shi, Wei; Jiang, Lide

    2012-01-16

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

  1. A study on the role of land-atmosphere coupling on the south Asian monsoon climate variability using a regional climate model

    NASA Astrophysics Data System (ADS)

    Unnikrishnan, C. K.; Rajeevan, M.; Vijaya Bhaskara Rao, S.

    2015-11-01

    Land-atmosphere coupling over the south Asian monsoon region is examined using a regional climate model. For this purpose, the Weather Research and Forecasting (WRF) model with a resolution of 45 km was used. In the control experiment (CTL), the model was integrated from the year 2000 to 2011 and allowed the soil moisture interaction with the atmosphere using a coupled land surface model. In the second experiment (CSM), the soil moisture evolution at each time step was replaced with the climatology of soil moisture taken from the control run. The results reveal that land-atmosphere coupling plays a critical role in influencing the south Asian monsoon climate variability. Soil moisture is found to have stronger impacts on daily maximum temperature compared to minimum temperature. Soil moisture also makes a significant contribution to monsoon rainfall variability over the monsoon region. The coupling strength for large-scale rainfall is found to be higher compared to that of cumulus rainfall. Soil moisture is found more strongly coupled to sensible heat flux over most of the monsoon region.

  2. 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 δ202Hg = 0.44 ± 0.05‰, 1SD, n = 3), (2) marine-influenced sources derived from the Gulf of Mexico (mean δ202Hg = 0.77 ± 0.15‰, 1SD, n = 4), (3) continental sources associated with north-northwesterly flows from within the planetary boundary layer (mean δ202Hg = 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 δ202Hg = 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 δ202Hg values; that urban-industrial emissions drive the isotopic composition of ambient atmospheric mercury toward lower δ202Hg 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 δ202Hg 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.

  3. Global electric circuit influences on cloud microphysics, precipitation, and atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Tinsley, B.

    2003-04-01

    The current flow in the global electric circuit links space weather and changes in the upper atmosphere levels down to tropospheric cloud levels, where it appears to influence precipitation from certain types of clouds, that in turn may influence atmospheric dynamics. The current flow is also affected by internal atmospheric processes. Thus, there is an expectation that changes in clouds globally could also be linked to changes in tropical thunderstorms that act as electrical generators for the circuit. A brief review will be given of the effects on the global circuit of energetic particle precipitation and changes in polar cap ionospheric potential. The energetic particles are galactic cosmic rays (at all times) and MeV electrons and solar protons (occasionally, when the stratospheric column resistance is enhanced by volcanic aerosols or stratospheric clouds). The current density into clouds generates space charge in conductivity gradients, such as at the upper and lower boundaries of the clouds, and provides the charge for electroscavenging processes, as well as for ion-mediated-nucleation. Both processes appear capable of affecting the concentrations of CCN. Electroscavenging enhances contact ice nucleation in cloud tops that are supercooled with broad droplet size distributions, e.g., marine stratocumulus in winter. Estimates give greater contact nucleation rates than deposition nucleation rates in slightly supercooled cloud tops. Increases in ice nucleation and decreases in CCN concentration enhance the processes leading to precipitation and reduction in cloud cover. Enhanced precipitation in certain circumstances can lead to intensification of winter cyclones, with possible consequences for blocking situations in the general circulation.

  4. Influence of water vapour and permanent gases on the atmospheric optical depths and transmittance

    NASA Astrophysics Data System (ADS)

    Badescu, V.

    1991-05-01

    The influence of the atmospheric state on the extinction of direct solar radiation has been studied by using a four layer atmospheric model. Simple analytical formulae are established for the spectral optical depths of permanent gases and water vapour. These formulae use the ground level values of air pressure, temperature and relative huniidity. An additional parameter, related to the vertical distribution of the hunmidity content, is used for a better estimation of the water vapour optical depth. Good agreement between theory and measurements is found. The paper shows the dependence of the atmospheric spectral transmittance on the above mentioned parameters. L'influence de l'état atmosphérique sur l'extinction de la radiation solaire directe a été étudiée à l'aide d'un modèle atmosphérique développé antérieurement par l'auteur. Des formules simples ont été établies pour l'épaisseur optique spectrale des gaz et de la vapeur d'eau. Ces formules utilisent les valeurs de la pression atmosphérique, de la température et de l'humidité relative, mesurées au niveau du sol. Un paramètre supplémentaire, lié à la distribution verticale du contenu d'humidité, est utilisé pour calculer l'épaisseur optique due à la vapeur d'eau. La théorie est en bon accord avec les résultats des mesures. Le travail montre la dépendance de la transmittance atmosphérique spectrale en fonction des paramètres spécifiés ci-dessus.

  5. Characterizing the Influence of Hemispheric Transport on Regional Air Pollution

    EPA Science Inventory

    Expansion of the coupled WRF-CMAQ modeling system to hemispheric scales is pursued to enable the development of a robust modeling framework in which the interactions between atmospheric processes occurring at various spatial and temporal scales can be examined in a consistent man...

  6. Photometric properties of the surface of Io and their influence on line formation in the atmosphere

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.; Goody, R. M.

    1975-01-01

    A quantitative theory is given for line formation in an atmosphere above a surface with backscattering properties. Sufficiently high spatial and spectral resolution spectra of resonance lines in Io region A can yield data on the surface scattering properties as well as the number density of scattering molecules. Macroscopically homogeneous models of scattering from the surface of Io are discussed and it was concluded that multiple reflection from crystal facets is the most likely cause for the observed phase variations of the geometric albedo.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  8. Response of the solar atmosphere to magnetic field evolution in a coronal hole region

    NASA Astrophysics Data System (ADS)

    Yang, S. H.; Zhang, J.; Jin, C. L.; Li, L. P.; Duan, H. Y.

    2009-07-01

    Context: Coronal holes (CHs) are deemed to be the sources of the fast solar wind streams that lead to recurrent geomagnetic storms and have been intensively investigated, but not all the properties of them are well known. Aims: We study the response of the solar atmosphere to the magnetic field evolution in a CH region, such as magnetic flux emergence and cancellation for both network (NT) and intranetwork (IN) regions. Methods: We study an equatorial CH observed simultaneously by HINODE and STEREO on July 27, 2007. The HINODE/SP maps are adopted to derive the physical parameters of the photosphere and to investigate the magnetic field evolution and distribution. The G band and Ca ii H images with high tempo-spatial resolution from HINODE/BFI and the multi-wavelength data from STEREO/EUVI are utilized to study the corresponding atmospheric response of different overlying layers. Results: We explore an emerging dipole located at the CH boundary. Mini-scale arch filaments (AFs) accompanying the emerging dipole were observed with the Ca ii H line. During the separation of the dipolar footpoints, three AFs appeared and expanded in turn. The first AF divided into two segments in its late stage, while the second and third AFs erupted in their late stages. The lifetimes of these three AFs are 4, 6, 10 min, and the two intervals between the three divisions or eruptions are 18 and 12 min, respectively. We display an example of mixed-polarity flux emergence of IN fields within the CH and present the corresponding chromospheric response. With the increase of the integrated magnetic flux, the brightness of the Ca ii H images exhibits an increasing trend. We also study magnetic flux cancellations of NT fields located at the CH boundary and present the chromospheric and coronal response. We notice that the brighter regions seen in the 171 Å images are relevant to the interacting magnetic elements. By examining the magnetic NT and IN elements and the response of different atmospheric layers, we obtain close positive linear correlations between the NT magnetic flux densities and the brightness of both G band (correlation coefficient 0.85) and Ca ii H (correlation coefficient 0.58).

  9. 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.

  10. 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.

  11. 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.

  12. Atmospheric mercury in the Great Smoky Mountains compared to regional and global levels

    NASA Astrophysics Data System (ADS)

    Valente, Ralph J.; Shea, Catherine; Lynn Humes, K.; Tanner, Roger L.

    Improvements in measurement technology are permitting development of a more detailed scientific understanding of the cycling of mercury in the global atmospheric environment. Critical to advancing the state of knowledge is the acquisition of accurate measurement of speciated mercury (gaseous and particulate) at ground research stations in a variety of settings located around the globe. This paper describes one such research effort conducted at TVA's Look Rock air quality monitoring site in Tennessee—a mountain top site (813 m elevation) just west of the Great Smoky Mountains National Park. The Great Smoky Mountains National Park is the largest National Park in the eastern US and it receives environmental protection under a variety of US statutes. Gaseous and particle mercury species along with some additional trace gases were measured at Look Rock during two field studies totaling 84 days in the spring and summer of 2004. Average results for the entire sampling period are: gaseous elemental mercury Hg(0): 1.65 ng m -3, reactive gaseous mercury RGM: 0.005 ng m -3, particulate mercury Hg(p): 0.007 ng m -3. Literature review indicates that these levels are within the range found for other rural/remote sites in North America and worldwide. Reactive and particulate mercury comprised together less than 1%, on average, of total airborne mercury at Look Rock. When compared to the global background mercury literature, the Look Rock measurements demonstrate that the atmospheric mercury levels in the vicinity of the Great Smoky Mountains National Park are clearly dominated by the global atmospheric pool, not by local or regional sources.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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.

  16. Atmospheric CO2 source and sink patterns over the Indian region

    NASA Astrophysics Data System (ADS)

    Fadnavis, Suvarna; Kumar, K. Ravi; Tiwari, Yogesh K.; Pozzoli, Luca

    2016-02-01

    In this paper we examine CO2 emission hot spots and sink regions over India as identified from global model simulations during the period 2000-2009. CO2 emission hot spots overlap with locations of densely clustered thermal power plants, coal mines and other industrial and urban centres; CO2 sink regions coincide with the locations of dense forest. Fossil fuel CO2 emissions are compared with two bottom-up inventories: the Regional Emission inventories in ASia (REAS v1.11; 2000-2009) and the Emission Database for Global Atmospheric Research (EDGAR v4.2) (2000-2009). Estimated fossil fuel emissions over the hot spot region are ˜ 500-950 gC m-2 yr-1 as obtained from the global model simulation, EDGAR v4.2 and REAS v1.11 emission inventory. Simulated total fluxes show increasing trends, from 1.39 ± 1.01 % yr-1 (19.8 ± 1.9 TgC yr-1) to 6.7 ± 0.54 % yr-1 (97 ± 12 TgC yr-1) over the hot spot regions and decreasing trends of -0.95 ± 1.51 % yr-1 (-1 ± 2 TgC yr-1) to -5.7 ± 2.89 % yr-1 (-2.3 ± 2 TgC yr-1) over the sink regions. Model-simulated terrestrial ecosystem fluxes show decreasing trends (increasing CO2 uptake) over the sink regions. Decreasing trends in terrestrial ecosystem fluxes imply that forest cover is increasing, which is consistent with India State of Forest Report (2009). Fossil fuel emissions show statistically significant increasing trends in all the data sets considered in this study. Estimated trend in simulated total fluxes over the Indian region is ˜ 4.72 ± 2.25 % yr-1 (25.6 TgC yr-1) which is slightly higher than global growth rate ˜ 3.1 % yr-1 during 2000-2010.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. A Wintertime Investigation of Atmospheric Pollutants Deposition in the Alberta Oil Sands Region, Canada

    NASA Astrophysics Data System (ADS)

    Bari, M.; Kindzierski, W.

    2012-12-01

    Atmospheric deposition is a potentially important pathway of trace metals and polycyclic aromatic hydrocarbons (PAH) input to the landscape in the oil sands region of Alberta. With planned expansion of oil sands facilities, there is interest in being able to characterize the magnitude and extent of trace metal and PAH deposition in the oil sands region. A pilot study was undertaken to assess the feasibility of a bulk collection system to characterize atmospheric deposition of selected organic and inorganic contaminants in the Athabasca Oil Sands Region. The study was carried out in four sampling sites near and distant to oil sands facilities from late December 2011 to the end of March 2012 (3-month period). To check the precision of the bulk deposition method, triplicate bulk samplers were used, which were placed next to each other and as close as possible considering similar microenvironment. Monthly deposition samples were analyzed for 36 trace metals (including 13 U.S. EPA priority pollutants), ultra-low mercury, and 25 PAH (including alkylated-, parent-, and carcinogenic-PAH). At two sampling sites located within 20 km of major oil sands facilities, 3-month integrated deposition rates for some priority metals were up to 20-fold higher compared to two background sites located >45 km away from the oil sands facilities. Winter deposition rates of alkylated-PAH and parent-PAH were up to 70-fold lower at the background sampling sites than at sites near oil sands facilities. Deposition fluxes of total carcinogenic PAH were found to be 6- to 75-fold higher at the two sampling sites near oil sands development facilities compared to the north and south background sites. Another notable finding is the apparent precision of the sampling method. Median coefficient of variation for 13 priority metals were ±21% and within ±15% for both alkylated- and parent-PAH. The Athabasca oil sands region is considered a large area of current interest with respect to potential deposition of trace metals and PAH. However, access to power for any type of air pollution monitoring is, for the most part, lacking in locations at distances excess of 30 km from oil sands facilities. The bulk collection systems investigated here offer the ability to obtain direct measures of trace metal and PAH deposition in these remote areas.

  4. The Influence of Glacial Ice Sheets on Atlantic Meridional Overturning Circulation Through Atmospheric Circulation Change under Glacial Climate

    NASA Astrophysics Data System (ADS)

    Sherriff-Tadano, S.; Abe-Ouchi, A.; Yoshimori, M.; Oka, A.; Chan, W. L.

    2014-12-01

    It is well known that glacial ice sheets (Laurentide, Fennoscandian and Antarctic ice sheets) exert a large influence on the climate including the atmospheric circulation. Moreover, recent climate modeling studies suggest that glacial ice sheets have a large impact on the Atlantic meridional overturning circulation (AMOC). However, the process by which the ice sheets impact on the AMOC is not yet fully understood. On the other hand, recent studies showed that surface wind changes play a crucial role on changes to the AMOC under glacial climate. Therefore, in this study, we investigate in detail, the process by which the ice sheet modifies the AMOC through surface wind change. Here we conduct numerical experiments using an atmospheric general circulation model (AGCM) and an ocean general circulation model (OGCM) separately. Our method consists of 2 steps. First, from AGCM experiments, we evaluate the effect of glacial ice sheets on the surface wind. Second, from OGCM experiments, we evaluate the influence of the wind stress change on the AMOC by applying the surface wind change as a boundary condition, while leaving other boundary conditions (surface heat and water fluxes) unchanged. In addition, we conduct several sensitivity experiments. Using the AGCM, we explore individual ice sheet effect, ice sheet topography effect and albedo effect on surface wind change. Moreover, using the OGCM, we change the surface wind gradually or apply the surface wind change only at a specific region in order to explore the wind change effect in detail. We find that glacial ice sheets largely intensify the AMOC by surface wind change under glacial climate. Compare to other regions, it reveals that the wind change at the North Atlantic (NA) is a key region. There, the northern glacial ice sheet topography intensifies the Icelandic Low and anti-cyclonic circulation over the Laurentide ice sheet. However, this wind effect is effective only when the NA is not widely covered by sea ice. From our sensitivity experiments and previous studies, we conclude that glacial ice sheets intensify the AMOC thorough enhancing the salt transport at high latitude NA surface.

  5. Influence of radioactivity on surface charging and aggregation kinetics of particles in the atmosphere.

    PubMed

    Kim, Yong-Ha; Yiacoumi, Sotira; Lee, Ida; McFarlane, Joanna; Tsouris, Costas

    2014-01-01

    Radioactivity can influence surface interactions, but its effects on particle aggregation kinetics have not been included in transport modeling of radioactive particles. In this research, experimental and theoretical studies have been performed to investigate the influence of radioactivity on surface charging and aggregation kinetics of radioactive particles in the atmosphere. Radioactivity-induced charging mechanisms have been investigated at the microscopic level, and heterogeneous surface potential caused by radioactivity is reported. The radioactivity-induced surface charging is highly influenced by several parameters, such as rate and type of radioactive decay. A population balance model, including interparticle forces, has been employed to study the effects of radioactivity on particle aggregation kinetics in air. It has been found that radioactivity can hinder aggregation of particles because of similar surface charging caused by the decay process. Experimental and theoretical studies provide useful insights into the understanding of transport characteristics of radioactive particles emitted from severe nuclear events, such as the recent accident of Fukushima or deliberate explosions of radiological devices. PMID:24308778

  6. OASIS: Ocean-Atmosphere-Sea-Ice-Snowpack Interactions in Polar Regions

    NASA Astrophysics Data System (ADS)

    Bottenheim, J. W.; Abbatt, J.; Beine, H.; Berg, T.; Bigg, K.; Domine, F.; Leck, C.; Lindberg, S.; Matrai, P.; MacDonald, R.; McConnell, J.; Platt, U.; Raspopov, O.; Shepson, P.; Shumilov, O.; Stutz, J.; Wolff, E.

    2004-05-01

    While Polar regions encompass a large part of the globe, little attention has been paid to the interactions between the atmosphere and its extensive snow-covered surfaces. Recent discoveries in the Arctic and Antarctic show that the top ten centimeters of snow is not simply a white blanket but in fact is a surprisingly reactive medium for chemical reactions in the troposphere. It has been concluded that interlinked physical, chemical, and biological mechanisms, fueled by the sun and occurring in the snow, are responsible for depletion of tropospheric ozone and gaseous mercury. At the same time production of highly reactive compounds (e.g. formaldehyde, nitrogen dioxide) has been observed at the snow surface. Air-snow interactions also have an impact on the chemical composition of the snow and hence the nature and amounts of material released in terrestrial/marine ecosystems during the melting of seasonal snow-packs. Many details of these possibly naturally occurring processes are yet to be discovered. For decades humans have added waste products including acidic particles (sulphates) and toxic contaminants such as gaseous mercury and POPs (persistent organic pollutants) to the otherwise pristine snow surface. Virtually nothing is known about transformations of these contaminants in the snowpack, making it impossible to assess the risk to the polar environment, including humans. This is especially disconcerting when considering that climate change will undoubtedly alter the nature of these transformations involving snow, ice, atmosphere, ocean, and, ultimately, biota. To address these topics an interdisciplinary group of scientists from North America, Europe and Japan is developing a set of coordinated research activities under the banner of the IGBP programs IGAC and SOLAS. The program of Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) interactions has been established with a mission statement aimed at determining the impact of OASIS chemical exchange on tropospheric chemistry and climate, as well as on the surface/biosphere and their feedbacks in the Polar regions of the globe. It is proposed that this program will culminate in a concerted field project during the IPY. In this contribution we will present the details of the emerging OASIS science plan and progress towards its implementation.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

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

    PubMed

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    SciTech Connect

    Osboum, Gordon C.; Martinez, Rubel F.; Bartholomew, John W.

    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 in 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.

  12. 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

  13. Atmospheric aerosols local-regional discrimination for a semi-urban area in India

    NASA Astrophysics Data System (ADS)

    Hooda, R. K.; Hyvärinen, A.-P.; Vestenius, M.; Gilardoni, S.; Sharma, V. P.; Vignati, E.; Kulmala, M.; Lihavainen, H.

    2016-02-01

    In the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI), measurements were carried out with a sequential filter-based aerosol sampler and on-line instruments for aerosol composition and behaviour at Gual Pahari, close to New Delhi. In fine mode (PM2.5), the secondary organic carbon (SOC) to total organic carbon ratio was 46%. This indicated that condensation of SOC on fine size particles could occur rapidly which may be related to the growth of aerosols and the potential to the size of cloud condensation nuclei in the region. Source region discrimination was improved significantly through coupling conditional probability functions with receptor modelling, and validation through volume size distribution. The air masses from industrial and dense populated regions show a mix of local as well as regional emissions to fine mode aerosols. The back-trajectory analysis captured the long-range transport of sea-salt aerosols enriched with mineral dust. The surface wind directions identified the influence of local emission activities.

  14. Applications of active remote sensing of CO2 to atmospheric studies of regional greenhouse gas sources and sinks (Invited)

    NASA Astrophysics Data System (ADS)

    Davis, K. J.; Browell, E. V.; Butler, M. P.; Denning, A.; Diaz Isaac, L. I.; Gibert, F.; Ismail, S.; Koch, G.; Lauvaux, T.; Miles, N. L.; Rayner, P. J.; Richardson, S.; Sweeney, C.

    2010-12-01

    Atmospheric greenhouse gas concentration measurements are a critical tool for the construction and verification of greenhouse gas source and sink estimates. While this has been done very effectively at global scales for decades, understanding the mechanisms governing the carbon cycle and monitoring the impact of regional to local attempts to manage the carbon cycle demand increasingly high resolution atmospheric inversions. High-resolution inversions require increasingly dense and accurate measurements of greenhouse gas concentrations, and high-resolution and accurate knowledge of atmospheric transport fields. Optical remote sensing of CO2 has the potential to fill important gaps in our current ability to construct regional to continental inversions of CO2 sources and sinks. Particularly pressing needs include quantification of the CO2 content of the entire tropospheric column and high density spatial sampling of atmospheric structures that transport CO2. Active optical remote sensing is well suited to evaluating the models used to construct regional to continental scale inversions, and for monitoring local boundary layer structure and concentrations. We will present our current understanding of regional CO2 mixing ratios at high spatial and temporal resolution, our current ability to model these spatial and temporal distributions, and our ability to infer sources and sinks of CO2 using these data. The presentation will highlight the issues that limit our ability to construct accurate regional atmospheric inversions, discuss how active optical remote sensing could be used to address these issues, and present some examples of progress to date.

  15. The influence of spectral nudging on typhoon formation in regional climate models

    NASA Astrophysics Data System (ADS)

    Feser, Frauke; Barcikowska, Monika

    2012-03-01

    Regional climate models can successfully simulate tropical cyclones and typhoons. This has been shown and was evaluated for hindcast studies of the past few decades. But often global and regional weather phenomena are not simulated at the observed location, or occur too often or seldom even though the regional model is driven by global reanalysis data which constitute a near-realistic state of the global atmosphere. Therefore, several techniques have been developed in order to make the regional model follow the global state more closely. One is spectral nudging, which is applied for horizontal wind components with increasing strength for higher model levels in this study. The aim of this study is to show the influence that this method has on the formation of tropical cyclones (TC) in regional climate models. Two ensemble simulations (each with five simulations) were computed for Southeast Asia and the Northwestern Pacific for the typhoon season 2004, one with spectral nudging and one without. First of all, spectral nudging reduced the overall TC number by about a factor of 2. But the number of tracks which are similar to observed best track data (BTD) was greatly increased. Also, spatial track density patterns were found to be more similar when using spectral nudging. The tracks merge after a short time for the spectral nudging simulations and then follow the BTD closely; for the no nudge cases the similarity is greatly reduced. A comparison of seasonal precipitation, geopotential height, and temperature fields at several height levels with observations and reanalysis data showed overall a smaller ensemble spread, higher pattern correlations and reduced root mean square errors and biases for the spectral nudged simulations. Vertical temperature profiles for selected TCs indicate that spectral nudging is not inhibiting TC development at higher levels. Both the Madden-Julian Oscillation and monsoonal precipitation are reproduced realistically by the regional model, with results slightly closer to reanalysis data for the spectral nudged simulations. On the basis of this regional climate model hindcast study of a single typhoon season, spectral nudging seems to be favourable since it has mostly positive effects on typhoon formation, location and general circulation patterns in the generation areas of TCs.

  16. 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.

  17. Nitrate Aerosol Partitioning in the 2003 Bay Regional Atmospheric Chemistry Experiment (BRACE) : Aloft and Surface Comparisons

    NASA Astrophysics Data System (ADS)

    Arnold, J. R.; Luke, W. T.; Watson, T. B.

    2003-12-01

    The Bay Regional Atmospheric Chemistry Experiment (BRACE) field intensive in May 2003 was designed to help understand nitrogen chemistry and cycling in the airshed of Tampa, FL and included gas-phase and aerosol measurements at two downwind urban locations (Sydney and Tower Dairy) and a bay shoreline location (Gandy) as well as aboard the NOAA Twin Otter aircraft. The Twin Otter made 21 flights in the greater Tampa region over urban, suburban, and rural areas, Tampa Bay, and the Gulf of Mexico. Among these flights were several vertical profiles extending from 60 to 3000 m MSL over the Bay, the Gulf, and the ground sites. Aerosol samples on the Twin Otter were made with high flow rate filter packs followed by IC analysis; surface measurements for aerosols were made with a combination of filter packs, MOUDI samplers, annular denuders, and near-real time wet denuder collection followed by IC analysis. The degree of nitrate partitioning observed with the Twin Otter filter pack samples onto fine (2.5u and smaller) and large aerosols is examined separately for the three flow regimes that predominated during the intensive: strong synoptic, when local effects were overwhelmed; synoptic shift, with wind shifts due to changing synoptic features; and sea/bay breeze, when local effects of the sea and bay breeze forced wind shifts. Analysis of these aloft results are then compared with nitrate aerosol values on the ground.

  18. 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.

  19. 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.

  20. Influence of scattering, atmospheric refraction, and ground effect on sound propagation through a pine forest.

    PubMed

    Swearingen, Michelle E; White, Michael J

    2007-07-01

    Sound propagation through a forest is affected by the microclimate in the canopy, scattering by trunks and stems, and ground reflection. Each of these effects is such a strong contributor to the attenuation of sound that mutual interactions between the phenomena could become important. A sound propagation model for use in a forest has been developed that incorporates scattering from trunks and branches and atmospheric refraction by modifying the effective wave number in the Green's function parabolic equation model. The ground effect for a hard-backed pine straw layer is approximated as a local reaction impedance condition. Comparisons to experimental data are made for frequencies up to 4,200 Hz. Cumulative influences of the separate phenomena are examined. The method developed in this paper is compared to previously published methods. The overall comparison with spectral transmission data is good, suggesting that the model captures the necessary details. PMID:17614470

  1. The influences of atmospheric half-yearly cycle on the sea ice extent in the Antarctic

    SciTech Connect

    Hiroyuki Enomoto; Atsumu Ohmura )

    1990-06-15

    The relationship between sea ice and weather, one of the least known components of the climatic system, could be an important factor for the climate of high latitudes. The annual cycle of the sea ice extent is characterized by a asymmetric development, with the sea ice area slowly advancing toward the equator in the winter and rapidly retreating in summer. In this study, the seasonal asymmetric behavior of ice extent and the changes in sea ice concentration are shown to be linked to the atmospheric convergence line (ACL) around Antarctica. It is found that the relative positions of the ACL characterized by the half-year cycle exert a strong influence upon the mean movement of the sea ice. It is also observed from the investigations of the areal concentration prior to the sea ice retreat is needed for a rapid retreat.

  2. 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.

  3. Atmospheric pressure plasma pretreatment of sugarcane bagasse: the influence of moisture in the ozonation process.

    PubMed

    Souza-Corrêa, J A; Oliveira, C; Wolf, L D; Nascimento, V M; Rocha, G J M; Amorim, J

    2013-09-01

    Sugarcane bagasse samples were pretreated with ozone via atmospheric O2 pressure plasma. A delignification efficiency of approximately 80 % was observed within 6 h of treatment. Some hemicelluloses were removed, and the cellulose was not affected by ozonolysis. The quantity of moisture in the bagasse had a large influence on delignification and saccharification after ozonation pretreatment of the bagasse, where 50 % moisture content was found to be best for delignification (65 % of the cellulose was converted into glucose). Optical absorption spectroscopy was applied to determine ozone concentrations in real time. The ozone consumption as a function of the delignification process revealed two main reaction phases, as the ozone molecules cleave the strong carbon-carbon bonds of aromatic rings more slowly than the weak carbon-carbon bonds of aliphatic chains. PMID:23817790

  4. 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.

  5. 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.

  6. Model assessment of atmospheric pollution control schemes for critical emission regions

    NASA Astrophysics Data System (ADS)

    Zhai, Shixian; An, Xingqin; Liu, Zhao; Sun, Zhaobin; Hou, Qing

    2016-01-01

    In recent years, the atmospheric environment in portions of China has become significantly degraded and the need for emission controls has become urgent. Because more international events are being planned, it is important to implement air quality assurance targeted at significant events held over specific periods of time. This study sets Yanqihu (YQH), Beijing, the location of the 2014 Beijing APEC (Asia-Pacific Economic Cooperation) summit, as the target region. By using the atmospheric inversion model FLEXPART, we determined the sensitive source zones that had the greatest impact on the air quality of the YQH region in November 2012. We then used the air-quality model Models-3/CMAQ and a high-resolution emissions inventory of the Beijing-Tianjian-Hebei region to establish emission reduction tests for the entire source area and for specific sensitive source zones. This was achieved by initiating emission reduction schemes at different ratios and different times. The results showed that initiating a moderate reduction of emissions days prior to a potential event is more beneficial to the air quality of Beijing than initiating a high-strength reduction campaign on the day of the event. The sensitive source zone of Beijing (BJ-Sens) accounts for 54.2% of the total source area of Beijing (BJ), but its reduction effect reaches 89%-100% of the total area, with a reduction efficiency 1.6-1.9 times greater than that of the entire area. The sensitive source zone of Huabei (HuaB-Sens.) only represents 17.6% of the total area of Huabei (HuaB), but its emission reduction effect reaches 59%-97% of the entire area, with a reduction efficiency 4.2-5.5 times greater than that of the total area. The earlier that emission reduction measures are implemented, the greater the effect they have on preventing the transmission of pollutants. In addition, expanding the controlling areas to sensitive provinces and cities around Beijing (HuaB-sens) can significantly accelerate the reduction effects compared to controlling measures only in the Beijing sensitive source zone (BJ-Sens). Therefore, when enacting emission reduction schemes, cooperating with surrounding provinces and cities, as well as narrowing the reduction scope to specific sensitive source zones prior to unfavorable meteorological conditions, can help reduce emissions control costs and improve the efficiency and maneuverability of emission reduction schemes.

  7. Influence of dielectric materials on radial uniformity in non-equilibrium atmospheric pressure helium plasma

    NASA Astrophysics Data System (ADS)

    Oda, Akinori; Komori, Kyohei

    2015-09-01

    Non-equilibrium atmospheric pressure plasma has been utilized for various technological applications such as surface treatment, materials processing, bio-medical and bio-logical applications. For optimum control of the plasma for the above applications, numerous experimental and theoretical investigations on the plasma have been reported. Especially, controlling radial uniformity of the plasma are very important for utilizing materials processing. In this paper, an axially-symmetric three-dimensional fluid model, which is composed of the continuity equation for charged and neutral species, the Poisson equation, and the energy conservation equation for electrons, of non-equilibrium atmospheric pressure helium plasma has been developed. Then, influence of dielectric properties (e.g. relative permittivity, secondary electron emission coefficient, etc.) of dielectric materials on radial plasma uniformity (i.e. radial distributions of electron density, ion density, electric field in the plasma) was examined. This work was partly supported by KAKENHI (No. 26420247), and a ``Grant for Advanced Industrial Technology Development (No. 11B06004d)'' in 2011 from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

  8. Osseointegration of atmospheric plasma-sprayed titanium implants: Influence of the native oxide layer.

    PubMed

    Cunha, Alexandre; Renz, Renata Pedrolli; Blando, Eduardo; de Oliveira, Rogério Belle; Hübler, Roberto

    2014-01-01

    The aim of this study was to evaluate in vivo the influence of the native oxide layer on osseointegration and new bone formation on the surface of atmospheric plasma-sprayed porous titanium coatings. Porous titanium coatings were deposited on all implant surfaces, and half of the samples were subsequently submitted to oxide layer removal treatment. Samples were implanted onto the cortical bone of sheep (tibia) and evaluated at 30 and 60 days. Implants were removed en bloc and the attachment of bone to implants was examined by tensile pull-out test (osseointegration assessment), light microscopy, scanning electron microscopy (histological analysis), and instrumented hardness tests (mechanical properties of mature and newly formed bone tissue). Coatings submitted to oxide layer treatment presented higher osseointegration values at both healing periods and showed more mature and mineralized bone tissue when compared with nontreated coatings. Our findings showed that the use of acid-etching in association with atmospheric plasma spraying techniques improves osseointegration of titanium implants. PMID:23568748

  9. 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.

  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. 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.

  12. Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of Central Asia

    NASA Astrophysics Data System (ADS)

    Li, K. H.; Song, W.; Liu, X. J.; Shen, J. L.; Luo, X. S.; Sui, X. Q.; Liu, B.; Hu, Y. K.; Christie, P.; Tian, C. Y.

    2012-06-01

    Atmospheric concentrations of reactive nitrogen species (Nr) from 2009 to 2011 are reported for ten sites in Xinjiang, an arid region in Northwest China. Concentrations of NH3, NO2, particulate ammonium and nitrate (pNH4+ and pNO3-) showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m-3, and PM10 concentrations averaged 249.2 μg m-3 across all sites. Lower NH3 concentrations and higher NO2, pNH4+ and pNO3- concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The order of increasing total concentrations of Nr species was alpine grassland < desert, desert-oasis ecotone < desert in an oasis < farmland < suburban and urban ecosystems. Lower ratios of secondary particles (NH4+ and NO3-) were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implies that anthropogenic activities have greatly influenced local air quality and must be controlled.

  13. Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of central Asia

    NASA Astrophysics Data System (ADS)

    Li, K. H.; Song, W.; Liu, X. J.; Shen, J. L.; Luo, X. S.; Sui, X. Q.; Liu, B.; Hu, Y. K.; Christie, P.; Tian, C. Y.

    2012-10-01

    Atmospheric concentrations of reactive nitrogen (Nr) species from 2009 to 2011 are reported for ten sites in Xinjiang, China, an arid region of central Asia. Concentrations of NH3, NO2, particulate ammonium and nitrate (pNH4+ and pNO3-) showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m-3, and PM10 concentrations averaged 249.2 μg m-3 across all sites. Lower NH3 concentrations and higher NO2, pNH4+ and pNO3- concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The increasing order of total concentrations of Nr species was alpine grassland; desert, desert-oasis ecotone; desert in an oasis; farmland; suburban and urban ecosystems. Lower ratios of secondary particles (NH4+ and NO3-) were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implied that anthropogenic activities have greatly influenced local air quality and must be controlled.

  14. 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.

  15. 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.

  16. Pollution influences on atmospheric composition and chemistry at high northern latitudes: Boreal and California forest fire emissions

    NASA Astrophysics Data System (ADS)

    Singh, H. B.; Anderson, B. E.; Brune, W. H.; Cai, C.; Cohen, R. C.; Crawford, J. H.; Cubison, M. J.; Czech, E. P.; Emmons, L.; Fuelberg, H. E.; Huey, G.; Jacob, D. J.; Jimenez, J. L.; Kaduwela, A.; Kondo, Y.; Mao, J.; Olson, J. R.; Sachse, G. W.; Vay, S. A.; Weinheimer, A.; Wennberg, P. O.; Wisthaler, A.; The Arctas Science Team

    2010-11-01

    We analyze detailed atmospheric gas/aerosol composition data acquired during the 2008 NASA ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) airborne campaign performed at high northern latitudes in spring (ARCTAS-A) and summer (ARCTAS-B) and in California in summer (ARCTAS-CARB). Biomass burning influences were widespread throughout the ARCTAS campaign. MODIS data from 2000 to 2009 indicated that 2008 had the second largest fire counts over Siberia and a more normal Canadian boreal forest fire season. Near surface arctic air in spring contained strong anthropogenic signatures indicated by high sulfate. In both spring and summer most of the pollution plumes transported to the Arctic region were from Europe and Asia and were present in the mid to upper troposphere and contained a mix of forest fire and urban influences. The gas/aerosol composition of the high latitude troposphere was strongly perturbed at all altitudes in both spring and summer. The reactive nitrogen budget was balanced with PAN as the dominant component. Mean ozone concentrations in the high latitude troposphere were only minimally perturbed (<5 ppb), although many individual pollution plumes sampled in the mid to upper troposphere, and mixed with urban influences, contained elevated ozone (ΔO 3/ΔCO = 0.11 ± 0.09 v/v). Emission and optical characteristics of boreal and California wild fires were quantified and found to be broadly comparable. Greenhouse gas emission estimates derived from ARCTAS-CARB data for the South Coast Air Basin of California show good agreement with state inventories for CO 2 and N 2O but indicate substantially larger emissions of CH 4. Simulations by multiple models of transport and chemistry were found to be broadly consistent with observations with a tendency towards under prediction at high latitudes.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  18. 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.

  19. 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

  20. Influence of daily versus monthly fire emissions on atmospheric model applications in the tropics

    NASA Astrophysics Data System (ADS)

    Marlier, M. E.; Voulgarakis, A.; Faluvegi, G.; Shindell, D. T.; DeFries, R. S.

    2012-12-01

    Fires are widely used throughout the tropics to create and maintain areas for agriculture, but are also significant contributors to atmospheric trace gas and aerosol concentrations. However, the timing and magnitude of fire activity can vary strongly by year and ecosystem type. For example, frequent, low intensity fires dominate in African savannas whereas Southeast Asian peatland forests are susceptible to huge pulses of emissions during regional El Niño droughts. Despite the potential implications for modeling interactions with atmospheric chemistry and transport, fire emissions have commonly been input into global models at a monthly resolution. Recognizing the uncertainty that this can introduce, several datasets have parsed fire emissions to daily and sub-daily scales with satellite active fire detections. In this study, we explore differences between utilizing the monthly and daily Global Fire Emissions Database version 3 (GFED3) products as inputs into the NASA GISS-E2 composition climate model. We aim to understand how the choice of the temporal resolution of fire emissions affects uncertainty with respect to several common applications of global models: atmospheric chemistry, air quality, and climate. Focusing our analysis on tropical ozone, carbon monoxide, and aerosols, we compare modeled concentrations with available ground and satellite observations. We find that increasing the temporal frequency of fire emissions from monthly to daily can improve correlations with observations, predominately in areas or during seasons more heavily affected by fires. Differences between the two datasets are more evident with public health applications: daily resolution fire emissions increases the number of days exceeding World Health Organization air quality targets.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  2. 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.

  3. Magnetosphere-Ionosphere Coupling in the Region of Electron Diffuse Aurora: The Role of Multiple Atmospheric Reflections

    NASA Astrophysics Data System (ADS)

    Himwich, E. W.; Khazanov, G. V.

    2014-12-01

    In the diffuse aurora, precipitating electrons initially injected from the plasmasheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These precipitating electrons can be additionally reflected back into the magnetosphere by the conjugate atmospheres, leading to a series of multiple reflections that can greatly influence precipitating flux at the upper ionospheric boundary (700-800 km) and the resultant secondary electron population. We present the solution of the Boltzmann-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E < 600 eV). This solution takes into account, for the first time, the role of multiple atmospheric reflections of the precipitated electrons that initially were moved into the loss cone via wave-particle interaction processes in the Earth's plasmasheet.

  4. Atmospheric composition in the Eastern Mediterranean: Influence of biomass burning during summertime using the WRF-Chem model

    NASA Astrophysics Data System (ADS)

    Bossioli, E.; Tombrou, M.; Kalogiros, J.; Allan, J.; Bacak, A.; Bezantakos, S.; Biskos, G.; Coe, H.; Jones, B. T.; Kouvarakis, G.; Mihalopoulos, N.; Percival, C. J.

    2016-05-01

    The composition of the atmosphere over the Aegean Sea (AS) during an 'Etesian' outbreak under the influence of biomass burning (BB) activity is investigated. Simulations with the fully coupled WRF-Chem model during the Aegean-GAME campaign (29/8-9/9/2011) are used to examine the BB effect over the region. Two distinct Etesian flow patterns characterized by different transport conditions are analysed. The influence of the off-line calculated BB emissions on the atmospheric chemical composition over the AS under these conditions is estimated. In addition, sensitivity runs are used to examine the influence of the biogenic emissions calculated on-line and the realistic representation of the stratosphere-troposphere exchange processes are investigated through the time-varying chemical boundary conditions from the MOZART global chemical transport model. The horizontal and vertical distributions of gaseous and aerosol species are simulated under long-range transport conditions and interpreted in relation to the evolution of the Planetary Boundary Layer (PBL). In the case of a weaker synoptic system (medium-range transport conditions), even a small variability of meteorological parameters in limited areas become critical for the spatial distribution of gases and aerosols. The BB activity increases O3, PM2.5 and organic matter concentrations up to 5.5 ppb, 5.8 μg m-3 and 3.3 μg m-3, respectively. The spatial extent of the simulated BB plumes is further examined by comparison with airborne measurements of hydrogen cyanide (HCN). The estimated effect of biogenic emissions on O3 and PM2.5 concentrations is either positive or negative (±6 ppb for O3 and up to ± 1 μg m-3 for PM2.5) depending on the emission algorithm employed. The realistic representation of the chemical boundary conditions reproduces an observed layer rich in O3 above 4 km, but also increases O3 concentrations inside the PBL by up to 40%.

  5. The influence of a very large wind farm on turbulent transport in the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Abkar, M.; Porté-Agel, F.

    2012-04-01

    Predicting wind and turbulent transport of heat, water vapor and pollutants through wind farms is of great importance for wind engineering, wind energy and environmental applications. It requires detailed knowledge of atmospheric boundary-layer (ABL) over a wide range of spatial and temporal scales. The complexity of such flows makes it difficult to obtain all the needed information through field experiments alone, and often necessitates high-resolution eddy-resolving numerical tools such as large-eddy simulation (LES). In this study, Large-eddy simulation is used to simulate atmospheric boundary-layer flow through a very large wind farm. To do this, tuning-free Lagrangian scale-dependent dynamic models (Stoll and Porte-Agel 2006) are used to model the subgrid-scale fluxes and the turbine-induced forces are parameterized using the actuator disk model (Wu and Porte-Agel 2011). The effect of large arrays of wind turbines on local/regional fluxes of momentum and scalar quantities under different stability conditions is assessed. Also, it will be shown how wind farms can change the vertical distribution of momentum and scalar fluxes inside the ABL. Particular attention is placed on the growth of the boundary layer height due to the presence of the wind turbines.

  6. 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.

  7. Reactive Atmospheric Plasma Spraying of AlN Coatings: Influence of Aluminum Feedstock Particle Size

    NASA Astrophysics Data System (ADS)

    Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

    2011-03-01

    Feedstock powder characteristics (size distribution, morphology, shape, specific mass, and injection rate) are considered to be one of the key factors in controlling plasma-sprayed coatings microstructure and properties. The influence of feedstock powder characteristics to control the reaction and coatings microstructure in reactive plasma spraying process (RPS) is still unclear. This study, investigated the influence of feedstock particle size in RPS of aluminum nitride (AlN) coatings, through plasma nitriding of aluminum (Al) feedstock powders. It was possible to fabricate AlN-based coatings through plasma nitriding of all kinds of Al powders in atmospheric plasma spray (APS) process. The nitriding ratio was improved with decreasing the particle size of feedstock powder, due to improving the nitriding reaction during flight. However, decreasing the particle size of feedstock powder suppressed the coatings thickness. Due to the loss of the powder during the injection, the excessive vaporization of fine Al particles and the completing nitriding reaction of some fine Al particles during flight. The feedstock particle size directly affects on the nitriding, melting, flowability, and the vaporization behaviors of Al powders during spraying. It concluded that using smaller particle size powders is useful for improving the nitriding ratio and not suitable for fabrication thick AlN coatings in reactive plasma spray process. To fabricate thick AlN coatings through RPS, enhancing the nitriding reaction of Al powders with large particle size during spraying is required.

  8. Evidence of Energy Supply by Active-Region Spicules to the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Zeighami, S.; Ahangarzadeh Maralani, A. R.; Tavabi, E.; Ajabshirizadeh, A.

    2016-03-01

    We investigate the role of active-region spicules in the mass balance of the solar wind and energy supply in heating the solar atmosphere. We use high-cadence observations from the Solar Optical Telescope (SOT) onboard the Hinode satellite in the Ca uc(ii) H-line filter obtained on 26 January 2007. The observational technique provides the high spatio-temporal resolution required to detect fine structures such as spicules. We apply a Fourier power spectrum and wavelet analysis to Hinode/SOT time series of an active-region data set to explore the existence of coherent intensity oscillations. Coherent waves could be evidence of energy transport that serves to heat the solar atmosphere. Using time series, we measure the phase difference between two intensity profiles obtained at two different heights, which gives information about the phase difference between oscillations at those heights as a function of frequency. The results of a fast Fourier transform (FFT) show peaks in the power spectrum at frequencies in the range from 2 to 8 mHz at four different heights (above the limb), while the wavelet analysis indicates dominant frequencies similar to those of the Fourier power spectrum results. A coherency study indicates coherent oscillations at about 5.5 mHz (3 min). We measure mean phase speeds in the range 250 - 425 km s^{-1} increasing with height. The energy flux of these waves is estimated to be F = 1.8 × 106 - 11.2 × 106 erg cm^{ - 2} s^{ - 1} or 1.8 - 11.2 kW m^{ - 2}, which indicates that they are sufficiently energetic to accelerate the solar wind and heat the corona to temperatures of several million degrees. We compute the the mass flux carried by spicules of 3 × 10^{ - 10} - 2 × 10^{ - 9} g cm^{ - 2} s^{ - 1}, which is 10 - 60 times higher than the mass that is carried away from the corona because of the solar wind (about 3 × 10^{ - 11} g cm^{ - 2} s^{ - 1}). Therefore, our results indicate that about 0.02 - 0.1 of the spicule mass is ejected from the corona, while the remainder reverts to the chromosphere. In other words, spicules can supply the mass lost due to the slow solar wind.

  9. Evidence of Energy Supply by Active-Region Spicules to the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Zeighami, S.; Ahangarzadeh Maralani, A. R.; Tavabi, E.; Ajabshirizadeh, A.

    2016-03-01

    We investigate the role of active-region spicules in the mass balance of the solar wind and energy supply in heating the solar atmosphere. We use high-cadence observations from the Solar Optical Telescope (SOT) onboard the Hinode satellite in the Ca ii H-line filter obtained on 26 January 2007. The observational technique provides the high spatio-temporal resolution required to detect fine structures such as spicules. We apply a Fourier power spectrum and wavelet analysis to Hinode/SOT time series of an active-region data set to explore the existence of coherent intensity oscillations. Coherent waves could be evidence of energy transport that serves to heat the solar atmosphere. Using time series, we measure the phase difference between two intensity profiles obtained at two different heights, which gives information about the phase difference between oscillations at those heights as a function of frequency. The results of a fast Fourier transform (FFT) show peaks in the power spectrum at frequencies in the range from 2 to 8 mHz at four different heights (above the limb), while the wavelet analysis indicates dominant frequencies similar to those of the Fourier power spectrum results. A coherency study indicates coherent oscillations at about 5.5 mHz (3 min). We measure mean phase speeds in the range 250-425 km s^{-1} increasing with height. The energy flux of these waves is estimated to be F = 1.8 × 106-11.2 × 106 erg cm^{-2} s^{-1} or 1.8-11.2 kW m^{-2}, which indicates that they are sufficiently energetic to accelerate the solar wind and heat the corona to temperatures of several million degrees. We compute the the mass flux carried by spicules of 3 × 10^{-10}-2 × 10^{-9} g cm^{-2} s^{-1}, which is 10-60 times higher than the mass that is carried away from the corona because of the solar wind (about 3 × 10^{-11} g cm^{-2} s^{-1}). Therefore, our results indicate that about 0.02-0.1 of the spicule mass is ejected from the corona, while the remainder reverts to the chromosphere. In other words, spicules can supply the mass lost due to the slow solar wind.

  10. 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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Ovsak, A. S.

    2015-01-01

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

  13. Investigating the influence of regional climate and oceanography on marine radiocarbon reservoir ages in southwest New Zealand

    NASA Astrophysics Data System (ADS)

    Hinojosa, Jessica L.; Moy, Christopher M.; Prior, Christine A.; Eglinton, Timothy I.; McIntyre, Cameron P.; Stirling, Claudine H.; Wilson, Gary S.

    2015-12-01

    The New Zealand fjords are located at a latitude where distinct oceanic and atmospheric fronts separate carbon reservoirs of varying residence time. The marine radiocarbon reservoir age in this region is likely to deviate from the global average reservoir age over space and time as frontal boundaries migrate north and south. Here we present new estimates of modern radiocarbon reservoir age using the radiocarbon content of bivalve shells collected live before 1950. Multiple measurements from hydrographically distinct sites support the use of a ΔR, defined as the regional offset between measured and modeled marine radiocarbon reservoir age, of 59 ± 35 years for the New Zealand fjords. We also assess the radiocarbon content of bulk surface sediments throughout the fjord region. Sediment with a higher proportion of marine organic carbon has relatively less radiocarbon than more terrestrial sediment, suggesting a short residence time of organic carbon on land before deposition in the fjords. Additionally, we constrain reservoir age variability throughout the Holocene using coeval terrestrial and marine macrofossils. Although our modern results suggest spatial consistency in ΔR throughout the fjords, large deviations from the global average marine radiocarbon reservoir age exist in the paleo record. We find four ancient ΔR values, extending back to ˜10.2 cal kyr BP, to be negative or near zero. A likely cause of younger radiocarbon reservoir ages at select intervals throughout the Holocene is the increased influence of the Southern Hemisphere westerly winds, which cause extreme precipitation in the region that delivers terrestrial carbon, enriched in radiocarbon, to fjord basins. However, bivalve depth habitat may also influence radiocarbon content due to a stratified water column containing distinct carbon pools. This work highlights the need for thorough assessment of local radiocarbon cycling in similar regions of dynamic ocean/atmosphere frontal zones, especially fjords and other semi-restricted estuaries.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16-21 January period. Proton fluxes were greatly increased during these several days and led to the production of HOx (H, OH, HO2) and NOx (N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HOx and NOx constituents, and associated ozone reductions, due to these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH throughout the mesosphere in the 60-82.5° N latitude band due to the SPEs for most days in the 16-21 January 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 HOx 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 pptv in the lowermost mesosphere over the 16-18 January 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 16-29 January 2005. WACCM3 simulations show only minuscule HNO3 changes in the upper stratosphere during this time period. Polar mesospheric enhancements of NOx are computed to be greater than 50 ppbv during the SPE period due to the small loss rates during winter. Computed NOx increases, which were statistically significant at the 95% level, lasted about a month past the SPEs. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer NOx measurements and MIPAS NO2 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 20 January 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16-21 January period. Proton fluxes were greatly increased during these several days and led to the production of HOx (H, OH, HO2) and NOx (N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HOx and NOx constituents, and associated ozone reductions, due to these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH and HO2 concentrations throughout the mesosphere in the 60-82.5° N latitude band due to the SPEs for most days in the 16-21 January 2005 period, somewhat higher in abundance than those observed by the Aura Microwave Limb Sounder (MLS). These HOx 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 pptv in the lowermost mesosphere over the 16-18 January 2005 period due to the solar protons. WACCM3 predictions indicate H2O2 enhancements over the same time period of about three times 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 16-29 January 2005. WACCM3 simulations show only minuscule HNO3 increases (<0.05 ppbv) in the upper stratosphere during this time period. Polar mesospheric enhancements of NOx are computed to be greater than 50 ppbv during the SPE period due to the small loss rates during winter. Computed NOx increases, which were statistically significant at the 95 % level, lasted about a month past the SPEs. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer NOx measurements and MIPAS NO2 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 20 January 2005. We find that protons of energies 300 to 20 000 MeV, associated with this GLE, led to very small enhanced lower stratospheric odd nitrogen concentrations of less than 0.1 % and ozone decreases of less than 0.01 %.

  17. 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.

  18. 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

    2016-05-01

    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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  1. Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region

    NASA Astrophysics Data System (ADS)

    Parrish, D. D.; Ryerson, T. B.; Mellqvist, J.; Johansson, J.; Fried, A.; Richter, D.; Walega, J. G.; Washenfelder, R. A.; de Gouw, J. A.; Peischl, J.; Aikin, K. C.; McKeen, S. A.; Frost, G. J.; Fehsenfeld, F. C.; Herndon, S. C.

    2011-12-01

    We evaluate the rates of secondary production and primary emission of formaldehyde (CH2O) from petrochemical industrial facilities and on-road vehicles in the Houston Texas region. This evaluation is based upon ambient measurements collected during field studies in 2000, 2006 and 2009. The predominant CH2O source (92 ± 4% of total) is secondary production formed during the atmospheric oxidation of highly reactive volatile organic compounds (HRVOCs) emitted from the petrochemical facilities. Smaller contributions are primary emissions from these facilities (4 ± 2%), and secondary production (~3%) and primary emissions (~1%) from vehicles. The primary emissions from both sectors are well quantified by current emission inventories. Since secondary production dominates, control efforts directed at primary CH2O emissions cannot address the large majority of CH2O sources in the Houston area, although there may still be a role for such efforts. Ongoing efforts to control alkene emissions from the petrochemical facilities, as well as volatile organic compound emissions from the motor vehicle fleet, will effectively reduce the CH2O concentrations in the Houston region. We have not addressed other emission sectors, such as off-road mobile sources or secondary formation from biogenic hydrocarbons. Previous analyses based on correlations between ambient concentrations of CH2O and various marker species have suggested much larger primary emissions of CH2O, but those results neglect confounding effects of dilution and loss processes, and do not demonstrate the causes of the observed correlations. Similar problems must be suspected in any source apportionment analysis of secondary species based upon correlations of ambient concentrations of pollutants.

  2. Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region

    NASA Astrophysics Data System (ADS)

    Parrish, D. D.; Ryerson, T. B.; Mellqvist, J.; Johansson, J.; Fried, A.; Richter, D.; Walega, J. G.; Washenfelder, R. A.; de Gouw, J. A.; Peischl, J.; Aikin, K. C.; McKeen, S. A.; Frost, G. J.; Fehsenfeld, F. C.; Herndon, S. C.

    2012-04-01

    We evaluate the rates of secondary production and primary emission of formaldehyde (CH2O) from petrochemical industrial facilities and on-road vehicles in the Houston Texas region. This evaluation is based upon ambient measurements collected during field studies in 2000, 2006 and 2009. The predominant CH2O source (92 ± 4% of total) is secondary production formed during the atmospheric oxidation of highly reactive volatile organic compounds (HRVOCs) emitted from the petrochemical facilities. Smaller contributions are primary emissions from these facilities (4 ± 2%), and secondary production (~3%) and primary emissions (~1%) from vehicles. The primary emissions from both sectors are well quantified by current emission inventories. Since secondary production dominates, control efforts directed at primary CH2O emissions cannot address the large majority of CH2O sources in the Houston area, although there may still be a role for such efforts. Ongoing efforts to control alkene emissions from the petrochemical facilities, as well as volatile organic compound emissions from the motor vehicle fleet, will effectively reduce the CH2O concentrations in the Houston region. We do not address other emission sectors, such as off-road mobile sources or secondary formation from biogenic hydrocarbons. Previous analyses based on correlations between ambient concentrations of CH2O and various marker species have suggested much larger primary emissions of CH2O, but those results neglect confounding effects of dilution and loss processes, and do not demonstrate the causes of the observed correlations. Similar problems must be suspected in any source apportionment analysis of secondary species based upon correlations of ambient concentrations of pollutants.

  3. 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.

  4. 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.

  5. Volcanic emissions of mercury to the atmosphere: global and regional inventories.

    PubMed

    Nriagu, Jerome; Becker, Christian

    2003-03-20

    A comprehensive, time-averaged inventory of subaerial emissions of mercury from volcanoes that were active between 1980 and 2000 is derived based on the Hg/SO(2) ratios of the exhalations. Worldwide flux of mercury from volcanic eruptions is estimated to be 57 t/year while the flux from degassing activities is 37.6 t/year. After correcting for 'unmeasured' SO(2) emissions, the total global flux of Hg to the atmosphere is estimated to be 112 t/year. There are regional differences in average emissions during the 20-year period, with the estimated fluxes being 29 t/year in South and Central America, 27 t/year in Southeast Asia; 24 t/year in North America (including Hawaii), 4.1 t/year in Australia, 3.4 t/year in Japan and northern Asia, 3.1 t/year in Europe and western Asia and 2.3 t/year in Africa. PMID:12663167

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    PubMed

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

    2014-07-15

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

  14. 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.

  15. 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 o