These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Influence of atmospheric circulation on regional 14CO2 differences  

Microsoft Academic Search

Detailed analyses of published 14C data from tree rings and atmospheric CO2 samples for the northern tropics in Asia (India, Thailand, and Vietnam) and Africa (Ethiopia) have been performed for the heavily bomb-influenced period 1963–1967 A.D. The results show that the Asian summer monsoon and Intertropical Convergence Zone (ITCZ) position influenced atmospheric 14CO2 over the study area. Similar analyses of

Quan Hua; Mike Barbetti

2007-01-01

2

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

SciTech Connect

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

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

1991-08-01

3

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

SciTech Connect

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.

Berkowitz, C.M.; Fast, J.D. [Pacific Northwest Lab., Richland, WA (United States)

1996-12-31

4

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

NASA Astrophysics Data System (ADS)

The study examines simulation of atmospheric circulation, represented by circulation indices (flow direction, strength and vorticity), and links between circulation and daily surface air temperatures in regional climate models (RCMs) over Central Europe. We explore control simulations of five high-resolution RCMs from the ENSEMBLES project driven by re-analysis (ERA-40) and the same global climate model (ECHAM5 GCM) plus of one RCM (RCA) driven by different GCMs. The aims are to (1) identify errors in RCM-simulated distributions of circulation indices in individual seasons, (2) identify errors in simulated temperatures under particular circulation indices, and (3) compare performance of individual RCMs with respect to the driving data. Although most of the RCMs qualitatively reflect observed distributions of the airflow indices, each produces distributions significantly different from the observations. General biases include overestimation of the frequency of strong flow days and of strong cyclonic vorticity. Some circulation biases obviously propagate from the driving data. ECHAM5 and all simulations driven by ECHAM5 underestimate frequency of easterly flow, mainly in summer. Except for HIRHAM, however, all RCMs driven by ECHAM5 improve on the driving GCM in simulating atmospheric circulation. The influence on circulation characteristics in the nested RCM differs between GCMs, as demonstrated in a set of RCA simulations with different driving data. The driving data control on circulation in RCA is particularly weak for the BCM GCM, in which case RCA substantially modifies (but does not improve) the circulation from the driving data in both winter and summer. Those RCMs with the most distorted atmospheric circulation are HIRHAM driven by ECHAM5 and RCA driven by BCM. Relatively strong relationships between circulation indices and surface air temperatures were found in the observed data for Central Europe. The links differ by season and are usually stronger for daily maxima than minima. RCMs qualitatively reproduce these relationships. Effects of the driving model biases were found on RCMs' performance in reproducing not only atmospheric circulation but also the links to surface temperature. However, the RCM formulation appears to be more important than the driving data in representing the latter. Differences of the circulation-to-temperature links among the RCA simulations are smaller and the links tend to be more realistic compared to the driving GCMs.

Plavcová, Eva; Kyselý, Jan

2012-10-01

5

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

6

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 30, NO. 2, 2013, 330340 The Influence of Regional SSTs on the Interdecadal Shift  

E-print Network

on the Interdecadal Shift of the East Asian Summer Monsoon FU Jianjian1 ( ) and LI Shuanglin1,2 ( ) 1 Climate Changes Academy of Sciences, Beijing 100029 2 Key Laboratory of Regional Climate-Environment for East Asia in the tropical Pacific Ocean, rather than the Indian Ocean, contributed significantly to the shift of East Asian

7

Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets  

SciTech Connect

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

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

2007-03-07

8

Future surface mass balance of the Antarctic ice sheet and its influence on sea level change, simulated by a regional atmospheric climate model  

NASA Astrophysics Data System (ADS)

A regional atmospheric climate model with multi-layer snow module (RACMO2) is forced at the lateral boundaries by global climate model (GCM) data to assess the future climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS). Two different GCMs (ECHAM5 until 2100 and HadCM3 until 2200) and two different emission scenarios (A1B and E1) are used as forcing to capture a realistic range in future climate states. Simulated ice sheet averaged 2 m air temperature (T2m) increases (1.8-3.0 K in 2100 and 2.4-5.3 K in 2200), simultaneously and with the same magnitude as GCM simulated T2m. The SMB and its components increase in magnitude, as they are directly influenced by the temperature increase. Changes in atmospheric circulation around Antarctica play a minor role in future SMB changes. During the next two centuries, the projected increase in liquid water flux from rainfall and snowmelt, together 60-200 Gt year-1, will mostly refreeze in the snow pack, so runoff remains small (10-40 Gt year-1). Sublimation increases by 25-50 %, but remains an order of magnitude smaller than snowfall. The increase in snowfall mainly determines future changes in SMB on the AIS: 6-16 % in 2100 and 8-25 % in 2200. Without any ice dynamical response, this would result in an eustatic sea level drop of 20-43 mm in 2100 and 73-163 mm in 2200, compared to the twentieth century. Averaged over the AIS, a strong relation between SMB and of 98 ± 5 Gt w.e. year-1 K-1 is found.

Ligtenberg, S. R. M.; van de Berg, W. J.; van den Broeke, M. R.; Rae, J. G. L.; van Meijgaard, E.

2013-08-01

9

Experimental evaluation of atmospheric aerosol turbidity in different Atlantic regions  

SciTech Connect

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

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

1994-12-31

10

Influence of aerosol source regions and transport pathway on ?D of terrestrial biomarkers in atmospheric aerosols from the East China Sea  

NASA Astrophysics Data System (ADS)

We measured stable hydrogen isotope ratios (?D) of terrestrial biomarkers (n-alkanes and n-fatty acids) in atmospheric total suspended particles collected at Jeju Island in the East China Sea, from April 2001 to March 2002, to better understand the influence of long-range atmospheric transport on their seasonal variations. The ?D values of the C27, C29 and C31n-alkanes (?DALK) show a significant negative correlation with the CPI values of n-alkanes (r2 = 0.26, p < 0.01), suggesting that the ?DALK variations are partly attributed to a superimposed contribution from fossil fuel hydrocarbons. Seasonal variations in the concentrations of the C22-C28 even-carbon numbered n-fatty acids revealed relatively high concentrations in spring, autumn and winter seasons, in which the air masses are transported from northeast Asia. In contrast, the concentrations are low in summer when the air masses are transported from Southeast Asia and the Pacific. Relatively high C26/FA and low C24/FA ratios in spring, autumn and winter samples suggest that the C26n-fatty acids are more abundantly transported from the Asian continent during these seasons. Seasonal variations in the ?D of the C22-C26 even-carbon numbered n-fatty acids exhibit significant enrichment with D (by ˜40‰) in May and June to August samples, whereas the ?D of the C28n-fatty acids gradually decrease during summer. The magnitude of the ?D offsets (˜45‰) between the C28n-fatty acid and the other homologues are much larger than those observed in East Asia spanning 18°N-50°N latitude (ca. 30‰), suggesting that the decoupling is likely attributed to the mixing of distinct source vegetation with different ?D ratios. Comparison of the weighted-mean ?D values of n-fatty acids (?DFA) between air mass source categories revealed relatively low values (˜-170‰) in samples with trajectories from the northeastern part of the Asian continent, supporting that the ?D analyses may be a powerful tool in deciphering the source regions of terrestrial biomarkers in atmospheric aerosols from the Asian continent. The results of this study provides important implications for paleoclimate studies that the ?D variations of long-range transported terrestrial biomarkers in remote ocean sediments may have recorded past changes in source strengths of the biomarkers and therefore have a potential to reconstruct paleo-wind patterns and transport of terrestrial carbon over the Pacific.

Yamamoto, Shinya; Kawamura, Kimitaka; Seki, Osamu; Kariya, Tadashi; Lee, Meehye

2013-04-01

11

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

PubMed

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

Singh, Ashima; Pandey, Jitendra

2012-08-01

12

Atmospheric Influence of Earth's Earliest Sulfur Cycle  

Microsoft Academic Search

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

James Farquhar; Huiming Bao; Mark Thiemens

2000-01-01

13

Regional Atmospheric Modeling of Caribbean Climate  

Microsoft Academic Search

We use the Regional Atmospheric Modeling System (RAMS) to simulate climatic pattern on the island of Puerto Rico. We hope our analyses will be used to determine the effects of climate change on other Caribbean and tropical islands. Our first experiments were to simulate the precipitation patterns on the island and the urban heat island effect. The main model configuration

A. Winter; J. Gonzalez; N. Ramirez; R. Vásquez

2002-01-01

14

Influence of usage and chemical-physical properties on the atmospheric transport and deposition of pesticides to agricultural regions of Manitoba, Canada.  

PubMed

This study quantified the masses of 14 pesticides deposited as wet (precipitation) versus dry (gaseous and particle) atmospheric deposition at a research farm in southwestern Manitoba, Canada. The concentration in air of these pesticides was also measured. Total bulk deposition amounts (wet+dry) ranged from 0.009 to 2.3 ?g m(-2) for the 12 pesticides detected, and for the six pesticides with both wet and dry deposition detections, dry deposition contributed 12-51% of the total deposition over the crop growing season. Although not applied at the site, eight herbicides registered for use in Canada, as well as lindane (?-HCH), were all frequently detected (92-100%) in the 12 air samples analyzed during the crop growing season, with by-product isomer ?-HCH (75%), clopyralid (50%) and atrazine (8%) detected to a lesser extent. The chemical's physicochemical properties and the relative mean mass of each agricultural pesticide applied in the province of Manitoba and in a 13 km radius were significant parameters in explaining the trends in the concentrations of pesticides detected in our samples. The important contribution of dry deposition to total pesticide deposition warrants greater attention in arid and semi-arid areas such as the Prairie Region of Canada, also because under a changing climate this region is estimated to experience more severe droughts while the more favorable conditions predicted for pest infestations could lead to increased pesticide applications in agricultural and urban areas. PMID:23260250

Messing, Paul; Farenhorst, Annemieke; Waite, Don; Sproull, Jim

2013-02-01

15

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

SciTech Connect

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

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

1991-08-01

16

Moon influence on equatorial atmospheric angular momentum  

NASA Astrophysics Data System (ADS)

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

Bizouard, Christian; Zotov, Leonid; Sidorenkov, Nikolay

2014-05-01

17

Influence of CO on Titan atmospheric reactivity  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

18

Ventriculoarterial coupling influences regional contractility.  

PubMed

The purpose of this study was to adjudicate whether concomitant manipulation of inotropic state and arterial elastance influences linear indices of regional contractility. Fifteen autonomically denervated open-chest porcine hearts were instrumented with midmyocardial ultrasonic crystals and aortic and left ventricular chamber microamanometers. Linear left anterior descending coronary artery regional stroke work vs preload relationships (RSW) were generated by 10-sec vena caval occlusion at control and altered contractile states (either dopamine, 5 micrograms/kg/min, or propranolol, 0.2 mg/kg) and following arterial elastance variation (phenylephrine or nitroprusside), effecting an average 30% change in mean arterial pressure (MAP). Global contractility (dP/dt) was doubled (227% of control) by dopamine and halved (35% of control) by propranolol at constant preload (end-diastolic volume, end-diastolic pressure) and afterload (MAP). Regional contractility (RSW slope) was increased from 135 +/- 11 to 211 +/- 28, P less than 0.01, by dopamine, but unchanged with propranolol (106 +/- 10 vs 118 +/- 14, NS). Bidirectional changes in aortic elastance depressed the dopamine-augmented RSW slope (115 +/- 17, nitroprusside; 132 +/- 14, phenylephrine; P less than 0.01 vs dopamine). These differences were attenuated by propranolol infusion (98 +/- 7, nitroprusside; 132 +/- 9, phenylephrine; NS vs propranolol). Thus, optimizing ventriculoarterial coupling should supersede simple afterload manipulation in perioperative cardiac support. PMID:2395366

Krukenkamp, I B; Silverman, N A; Arzouman, D; Badellino, M; Schmetterer, L; Levitsky, S

1990-09-01

19

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

20

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

Microsoft Academic Search

The influence of surface bidirectional reflectance factors, including shadowing, and of atmospheric aerosol variability are modelled for their effects on the remote sensing of desert targets from space in the 0·??m region at high spatial resolution. The white sand reflectance data of Salomonson are used as the basis for the simulation. The effects of the surface bi-directional reflectance and atmospheric

D. E. BOWKER; R. E. DAVIS

1992-01-01

21

REGIONAL-SCALE ATMOSPHERIC MERCURY MODELING  

EPA Science Inventory

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

22

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

E-print Network

to the town energy balance (TEB) urban canopy model. A control simulation was also performed withoutAtmospheric Environment 40 (2006) 1743­1758 Impact of urban heat island on regional atmospheric Abstract The purpose of this work is to study the impact of an urban land cover on local meteorology

Ribes, Aurélien

23

Ocean-atmosphere coupling over monsoon regions  

Microsoft Academic Search

In monsoon regions, the seasonal migration of the intertropical convergence zone (ITCZ) is manifested as a seasonal reversal of winds. Most of the summer monsoon rainfall over India occurs owing to synoptic and large-scale convection associated with the continental ITCZ (Fig. 1). We have investigated the interaction between these large-scale convective systems and the ocean over which they are generated1-3,

Sulochana Gadgil; P. V. Joseph; N. V. Joshi

1984-01-01

24

Yale's Environment School Power Plants Big Influence in Regional Mercury Emissions Introduction Knowledge  

E-print Network

Yale's Environment School · Power Plants Big Influence in Regional Mercury Emissions Introduction Power Plants Big Influence in Regional Mercury Emissions Related Topics: News Releases; Publications and Research Results; The Media The amount of mercury emitted to the atmosphere in the northeastern United

Lee, Xuhui

25

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

26

Identifying human influences on atmospheric temperature  

PubMed Central

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

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

2013-01-01

27

The Influence of Atmospheric Stability on Potential Evaporation  

Microsoft Academic Search

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

L. Mahrt; Michael Ek

1984-01-01

28

Impact of urban heat island on regional atmospheric pollution  

Microsoft Academic Search

The purpose of this work is to study the impact of an urban land cover on local meteorology and spatial distribution of atmospheric pollutants over the Paris region. One anticyclonic episode from the ESQUIF campaign was simulated using the meso-scale meteorological and chemical Meso-NHC model coupled to the town energy balance (TEB) urban canopy model. A control simulation was also

C. Sarrat; A. Lemonsu; V. Masson; D. Guedalia

2006-01-01

29

Investigating causes of regional variations in atmospheric carbon dioxide concentrations  

NASA Astrophysics Data System (ADS)

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.

Corbin, Katherine D.

30

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

32

Regional differences in worldwide emissions of mercury to the atmosphere  

Microsoft Academic Search

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

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

1996-01-01

33

Automated Detection of Oscillating Regions in the Solar Atmosphere  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

34

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

SciTech Connect

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.

Yang, R.

1992-01-01

35

The interplanetary magnetic field influences middle-latitude surface atmospheric pressure  

NASA Astrophysics Data System (ADS)

Results have been published over several decades that indicate a meteorological response in the polar regions to fluctuations in the east-west component of the interplanetary magnetic field (IMF), By. There is evidence that this Sun-weather coupling occurs via the global atmospheric electric field. It has been assumed that the effect maximises at high latitudes and is negligible at low and mid latitudes because the IMF-induced convection electric field is concentrated in the polar ionospheres. However, the spatial variation of the IMF-weather coupling has not previously been investigated in detail, neither have the global consequences of such forcing on the atmosphere. Here we demonstrate a previously unrecognised influence of IMF By on mid-latitude surface pressure. The difference between the mean surface pressure for high positive and high negative values of IMF By possesses a statistically-significant mid-latitude wave structure, similar in location and form to the cyclones and anti-cyclones produced by the action of atmospheric Rossby waves on the jet stream. Thus our results indicate that a mechanism that is known to produce atmospheric responses to the IMF in the polar regions is also able to modulate pre-existing weather patterns at mid-latitudes. A relatively localised and small amplitude solar influence on the upper atmosphere could therefore have an important effect, via the nonlinear evolution of storm tracks, on critical processes such as European climate and the breakup of Arctic sea ice.

Lam, Mai Mai; Chisham, Gareth; Freeman, Mervyn

2013-04-01

36

Critical review of studies on atmospheric dispersion in coastal regions  

SciTech Connect

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

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

1982-09-01

37

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

38

Role of solar influences on geomagnetosphere and upper atmosphere  

NASA Astrophysics Data System (ADS)

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

Kumar Tripathi, Arvind

39

Large-scale atmospheric response to eastern Mediterranean summer-autumn SST anomalies and the associated regional impact  

NASA Astrophysics Data System (ADS)

Since the Mediterranean Sea is halfway between subtropical and middle latitudes, and it represents a marginal oceanic region, research has tended to focus on how large-scale modes of atmospheric variability modulate its surface temperature. Conversely, the present study examines the potential influence of the Mediterranean Sea surface temperature (SST) anomalies on the Northern Hemisphere atmospheric circulation. In particular, this work explores the large-scale changes in the global circulation forced/influenced by the eastern Mediterranean summer-autumn SST pattern. To isolate the atmospheric response, AGCM sensitivity experiments with prescribed SST over the Mediterranean Sea and climatology elsewhere are analysed. Observational diagnostics upon the period used to define the boundary conditions (1979-2002) are also interpreted. Our results support the hypothesis of an atmospheric pattern initiated in the Mediterranean basin, pointing out both a local baroclinic response and a barotropic circumglobal anomaly. This atmospheric teleconnection pattern projects onto a hemispheric wave-like structure, reflecting the waveguide effect of the westerly jets. Results suggest, thereby, that the recurrent summer-autumn circumglobal teleconnection pattern can be excited locally by changes in the atmosphere over the Mediterranean region. A linear behaviour is found upon a regional impact over northeastern Africa. The remote impacts present however a nonlinear signature: anomalous warm conditions influencing on northern Europe and Euro-Asia, whereas anomalous cold conditions impacting more on the North Pacific basin. Limitations in our model setup are also discussed.

García-Serrano, J.; Polo, I.; Rodríguez-Fonseca, B.; Losada, T.

2013-11-01

40

Extensive regional atmospheric hydrocarbon pollution in the southwestern United States  

PubMed Central

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

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

2003-01-01

41

Influence of atmospheric turbulence on planetary transceiver laser ranging  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

42

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

NASA Astrophysics Data System (ADS)

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

Bolshunova, Tatiana; Ivan, Podkozlin

2013-04-01

43

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

44

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

NASA Astrophysics Data System (ADS)

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.

Lundin, R.

2010-09-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

46

Influence of the Laurentian Great Lakes on Regional Climate  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

47

Atmospheric energetics in regions of intense convective activity  

NASA Technical Reports Server (NTRS)

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

Fuelberg, H. E.

1977-01-01

48

Regional differences in worldwide emissions of mercury to the atmosphere  

NASA Astrophysics Data System (ADS)

Annual emissions of anthropogenic Hg to the atmosphere in different regions of the world during the last decade show an interesting dichotomy: the emissions in the developed countries increased at the rate of about 4.5-5.5% yr -1 up to 1989 and have since remained nearly constant, while in developing countries the emissions continue to rise steadily at the rate of 2.7-4.5% yr -1. On a global basis, however, the total anthropogenic emissions of Hg increased by about 4% yr -1 during the 1980s, peaked in 1989 at about 2290 t and are currently decreasing at the rate of about 1.3% yr -1. Solid waste disposal through incineration processes is the dominant source of atmospheric mercury in North America (˜ 40%), Central and South America (˜34%), western Europe (˜28%) and Africa (˜30%), whereas coal combustion remains the dominant source in Asia (˜42%) and eastern Europe and the former USSR (˜40%). Mining and smelting of Zn and Pb represent the major industrial source of Hg in Oceania (˜35%).

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

49

Regional forecasting with global atmospheric models; Final report  

SciTech Connect

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

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

1994-05-01

50

Atmospheric aerosol layers over Bangkok Metropolitan Region from CALIPSO observations  

NASA Astrophysics Data System (ADS)

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.

Bridhikitti, Arika

2013-06-01

51

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

Microsoft Academic Search

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

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

2002-01-01

52

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

53

Magnetic Field Influence on Atmospheric Escape and Planetary Evolution  

NASA Astrophysics Data System (ADS)

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

Driscoll, P. E.; Bercovici, D.

2012-12-01

54

Influence of equatorial diatom processes on Si deposition and atmospheric CO2 cycles at glacial//interglacial timescales  

E-print Network

Influence of equatorial diatom processes on Si deposition and atmospheric CO2 cycles at glacial equatorial and Antarctic regions, perhaps as a result of low river input. terminations in this scenario would: Biological and Chemical: Biogeochemical cycles (1615); KEYWORDS: diatoms, CO2, silicate Citation: Dugdale, R

Maine, University of

55

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 3, 2010, 575582 Influence of the Asian-Pacific Oscillation on Spring  

E-print Network

precipitation in this region. Key words: Asian-Pacific oscillation, precipitation over central eastern China, 1994), sea ice extent (Xue et al., 2003a; Zhao et al., 2004), East Asian upper- tropospheric airADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 3, 2010, 575­582 Influence of the Asian

56

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

NASA Astrophysics Data System (ADS)

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

Abkar, Mahdi; Porté-Agel, Fernando

2014-05-01

57

The influence of ionization events on atmospheric ozone  

NASA Technical Reports Server (NTRS)

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

Aikin, A. C.

1979-01-01

58

Modeling evaporation from porous media influenced by atmospheric processes  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

59

Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR)  

NSF Publications Database

... the lower atmosphere as well as to solar radiation and particle inputs from above. The activities ... the lower atmosphere as well as to solar radiation and particle inputs from above. The activities ...

60

Midlatitude D region variations measured from broadband radio atmospherics  

NASA Astrophysics Data System (ADS)

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

Han, Feng

61

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

NASA Astrophysics Data System (ADS)

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

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

2006-11-01

62

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

63

Regional scale evaporation and the atmospheric boundary layer  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

65

Atmospheric Correction of MERIS Data over Perialpine Regions  

Microsoft Academic Search

Accurate correction of atmospheric propagation effects is essential for quantitative retrieval of bio-geophysical properties at the Earth's surface from satellite radiance measurements. We studied procedures to obtain the MERIS at- surface reflectance at test sites on the northern and southern rim of the Alps, characterized by significant spatial and temporal variability of the atmospheric turbidity. The analysis is based on

Dana Floricioiu; Helmut Rott

2005-01-01

66

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

PubMed

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

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

2014-05-01

67

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

68

How does the atmospheric variability drive the aerosol residence time in the Arctic region?  

E-print Network

How does the atmospheric variability drive the aerosol residence time in the Arctic region? By M at characterising the impact of the atmospheric variability on the aerosol burden and residence time in the Arctic the Arctic region reach respectively maximums of 1.9 mg[S] m(2 , 0.2 mg m(2 and 6 mg m(2 , characteristic

Paris-Sud XI, Université de

69

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

70

Theoretical H II region models - The effects of stellar atmosphere models  

NASA Technical Reports Server (NTRS)

Several grids of theoretical H II region models are computed by photoionization modeling in order to determine the extent to which the choice of the ionizing stellar atmosphere model affects the calibration of emission-line diagnostic diagrams of Evans and Dopita (1985) and the semiempirical H II region abundance sequence calibration of Evans and Dopita. Emission-line diagnostic diagrams are presented and compared for model nebulae ionized by Hummer and Mihalas (1970) unblanketed LTE atmospheres, Kurucz (1979) line-blanketed LTE atmospheres, Mihalas (1972) unblanketed non-LTE, and a truncated blackbody spectrum. The models demonstrate that for solar nebular and atmospheric abundances, there are only minor differences between H II models ionized by the Hummer and Mihalas atmospheres. The unblanketed non-LTE stellar atmosphere models of Mihalas and truncated blackbody spectra are shown to be unsuitable for general H II region modelling.

Evans, I. N.

1991-01-01

71

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

NASA Astrophysics Data System (ADS)

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

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

72

RESEARCH ARTICLE Regional assessment on influence of landscape configuration  

E-print Network

RESEARCH ARTICLE Regional assessment on influence of landscape configuration and connectivity / Published online: 18 June 2009 Ã? United States Department of Agriculture/Animal Plant Health Inspection (Odocoileus virginianus) has broad implications for managing populations, agricultural damage, and disease

Clark, William R.

73

Short-term production and synoptic influences on atmospheric 7  

E-print Network

. This verifies the combined model of production and transport of the 7 Be radionuclide in the atmosphere.1029/ 2008JD011333. 1. Introduction [2] As modern atmospheric air transport models achieve higher level [2007]). Testing of air transport models can be done by measuring the concentration of tracing

74

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...

75

Medicanes in an ocean-atmosphere coupled regional climate model  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

76

Medicanes in an ocean-atmosphere coupled regional climate model  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

77

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

SciTech Connect

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

Leung, Lai R.; Qian, Yun

2009-02-12

78

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

79

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...

80

Coastal Zone Color Scanner atmospheric correction - Influence of El Chichon  

NASA Technical Reports Server (NTRS)

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

Gordon, Howard R.; Castano, Diego J.

1988-01-01

81

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

SciTech Connect

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

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

2000-05-01

82

Regional forecasting with global atmospheric models; Fourth year report  

SciTech Connect

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

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

1994-05-01

83

Physical Processes Influencing Atmospheric Trace Constituents Measured from Aircraft in Trace-P  

NASA Technical Reports Server (NTRS)

This paper presents a final report on physical processes influencing atmospheric trace constituents measured for aircraft in trace-P. This report covers the period of July 21, 2000 through October 31, 2003.

Newell, Reginald E.; Plumb, R. Alan

2003-01-01

84

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

E-print Network

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

85

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

86

28th International Cosmic Ray Conference 883 The Influence of the Global Atmospheric Properties on the  

E-print Network

28th International Cosmic Ray Conference 883 The Influence of the Global Atmospheric Properties dedicated to the Ultra High Energy Cosmic Rays (UHECR) and Neutrinos detection using the Earth's atmosphere) project is aimed to detect from space the Extensive Air Showers (EAS) produced by Ultra High Energy Cosmic

Boyer, Edmond

87

The Influence of Soil Wetness on Near-Surface Atmospheric Variability  

Microsoft Academic Search

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

Thomas Delworth; Syukuro Manabe

1989-01-01

88

Land Conversion in Amazonia and Northern South America; Influences on Regional Hydrology and Ecosystem Response  

NASA Astrophysics Data System (ADS)

A numerical model of the terrestrial biosphere (Ecosystem Demography Model) is compbined with an atmospheric model (Brazilian Regional Atmospheric Modeling System) to investigate how land conversion in the Amazon and Northern South America have changed the hydrology of the region, and to see if those changes are significant enough to produce an ecological response. Two numerical realizations of the structure and composition of terrestrial vegetation are used as boundary conditions in a simulation of the regional land surface and atmosphere. One realization seeks to capture the present day vegetation condition that includes human deforestation and land-conversion, the other is an estimate of the potential structure and composition of the region without human influence. Model output is assessed for consistent and significant differences in hydrometeorology. Locations that show compelling differences are taken as case studies. The seasonal biases in precipitation at these locations are then used to create perturbations to long-term climate datasets. These perturbations then drive long-term simulations of dynamic vegetation to see if the climate consistent with a potential regional vegetation could elicit a change in the vegetation equilibrium at the site. Results show that South American land conversion has had consistent impacts on the regional patterning of precipitation. At some locations, changes in precipitation are persistent and constitute a significant fraction of total precipitation. Land-conversion has decreased mean continental evaporation and increased mean moisture convergence. Case study simulations of long term vegetation dynamic indicate that a hydrologic climate consistent with regional potential vegetation can indeed have significant influence on ecosystem structure and composition, particularly in water limited growth conditions. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

Knox, Ryan Gary

89

Atmospheric influences on Gulf Stream fluctuations off Onslow Bay, North Carolina  

E-print Network

ATMOSPHERIC INFLUENCES ON GULF STREAM FLUCTUATIONS OFF ONSLOW BAY, NORTH CAROLINA A Thesis by ROBERT LESTER COHEN Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE December 1981 Major Subject: Oceanography ATMOSPHERIC INFLUENCES ON GULP STREAM FLUCTUATIONS OFF ONSLOW BAY, NORTH CAROLINA A Thesis by ROBERT LESTER COHEN Approved as to style and content by: (Chairman of Committee) (Member) (Member...

Cohen, Robert Lester

2012-06-07

90

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

92

Ionospheric E-region electron density and neutral atmosphere variations  

NASA Technical Reports Server (NTRS)

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

Stick, T. L.

1976-01-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

94

Adjoint modeling for atmospheric pollution process sensitivity at regional scale  

E-print Network

parameters. Used as forcing, meteorological data remain uncertain: recent studies show that, depending locations, Paris and a suburban site, the influence of both meteorological and chemical model parameters and solvent surface emissions and meteorological parameters such as temperature. Since the adjoint approach

Menut, Laurent

95

The influence of carbon exchange of a large lake on regional tracer-transport inversions: results from Lake Superior  

E-print Network

/034016/mmedia 1. Motivation Large lakes play a significant role in local atmospheric circulation and pollutantThe influence of carbon exchange of a large lake on regional tracer-transport inversions: results from Lake Superior This article has been downloaded from IOPscience. Please scroll down to see the full

Wisconsin at Madison, University of

96

Influence of atmospheric structure and topography on infrasonic wave propagation  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

97

The influence of ionization events on atmospheric ozone  

Microsoft Academic Search

Atmospheric ionization events can modify the concentration of neutral species in the stratosphere and mesosphere. In particular, ozone is destroyed because of the production of significant quantities of odd nitrogen and hydrogen compounds which react photochemically to destroy ozone. Direct evidence of ozone depletion comes from data taken during and following two solar flares generating large fluxes of 10-100 Mev

A. C. Aikin

1979-01-01

98

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

99

Observing system simulation experiments related to space-borne Lidar wind profiling. Part 2: Sensitivity to atmospheric and instrumental influences  

NASA Technical Reports Server (NTRS)

Three major potential sources of errors that influence the performance of the proposed LIDAR wind profiling systems are accounted for in the following simulation studies. First, the coherent CO2 laser system proposed by NOAA/ERL for the WINDSAT requires distributions of 10 microns size aerosol concentrations throughout the atmosphere to determine the Doppler shifted backscatter signal. Second, atmospheric influences such as clouds and precipitation affect the LIDAR system's ability to obtain complete vertical wind profiles. In this study, experiments are reported on in which the complete wind profiles are only available in model generated cloud-free regions down to model cloud tops. Third, constraints on the available power required for the expected operational lifetime duration of a LIDAR system govern the number of pulses which can be used to sample a 300 km square area.

Dlouhy, R.; Halem, M.

1984-01-01

100

Regional forecasting with global atmospheric models; Third year report  

SciTech Connect

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

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

1994-05-01

101

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

102

Effects of tropical deforestation on global and regional atmospheric chemistry  

Microsoft Academic Search

A major portion of tropospheric photochemistry occurs in the tropics. Deforestation, colonization, and development of tropical rain forest areas could provoke significant changes in emissions of radiatively and photochemically active trace gases. A brief review of studies on trace-gas emissions in pristine and disturbed tropical habitats is followed by an effort to model regional tropospheric chemistry under undisturbed and polluted

Michael Keller; Daniel J. Jacob; Steven C. Wofsy; Robert C. Harriss

1991-01-01

103

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

E-print Network

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

McSharry, Patrick E.

104

Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

106

Sensitivity of stationary wave amplitude to regional changes in Laurentide ice sheet topography in single-layer models of the atmosphere  

Microsoft Academic Search

Climate variability on millennial timescales has been observed in many geologic records covering the last glacial cycle. A potential source of this variability is the Laurentide ice sheet (LIS) in its periodic discharge of large quantities of icebergs to the North Atlantic. The present analysis considers whether regional variations in LIS topography could exert a significant influence on the atmosphere's

Charles Jackson

2000-01-01

107

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

SciTech Connect

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

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

2005-03-18

108

Longitudinal variations in the Saturnian atmosphere. I. Equatorial region  

SciTech Connect

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. 44 references.

Killen, R.M.

1988-02-01

109

Influence of interplanetary trajectory selection on Mars atmospheric entry velocity  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

110

The Sun's Influence on the Earh's Atmosphere and Interplanetary Space.  

PubMed

The bulk of the sun's radiation is in the visible and infrared. Solar radiation at these wavelengths controls the weather in the lowest levels of the earth's atmosphere. The rate at which this energy is emitted (the so-called solar constant) varies by a few tenths of 1 percent over a time scale of days. Longer period variations may exist, but have yet to be detected. Far more variable are the amounts of energy emitted as ultraviolet, extreme ultraviolet, and x-rays, and in the continuous outflow of ionized solar particles. The latter controls the properties of the space between the earth and the sun as well as those of the earth's magnetosphere. The ultraviolet and particle emissions control the properties of the earth's upper atmosphere, including the global wind circulation and changes therein associated with intense auroral storms. While considerable progress has been made in exploring the solar-terrestrial system since the advent of space research, many problems remain. These include the question of how magnetic energy is converted into ionized particle energy in the sun and in the earth's magnetosphere, the way in which solar and terrestrial magnetic fields join or merge, and how large electric fields are generated and sustained a few thousand kilometers above the earth's poles. Perhaps the most intriguing question concerns the possible relation between solar variability and the earth's weather and climate. PMID:17735724

Evans, J V

1982-04-30

111

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

SciTech Connect

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

Ramsdell, James V.; Rishel, Jeremy P.

2006-07-01

112

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

PubMed

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

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

2014-05-01

113

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

PubMed

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

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

2014-03-01

114

Assessment of regional seasonal rainfall predictability using the CPTEC\\/COLA atmospheric GCM  

Microsoft Academic Search

This is a study of the annual and interannual variability of regional rainfall produced by the Center for Weather Forecasts and Climate Studies\\/Center for Ocean, Land and Atmospheric Studies (CPTEC\\/COLA) atmospheric global climate model. An evaluation is made of a 9-member ensemble run of the model forced by observed global sea surface temperature (SST) anomalies for the 10-year period 1982–1991.

J. A. Marengo; I. F. A. Cavalcanti; P. Satyamurty; I. Trosnikov; C. A. Nobre; J. P. Bonatti; H. Camargo; G. Sampaio; M. B. Sanches; A. O. Manzi; C. A. C. Castro; C. D'Almeida; L. P. Pezzi; L. Candido

2003-01-01

115

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

116

Influence of the atmosphere on remotely sensed data. [multispectral pattern recognition effects  

NASA Technical Reports Server (NTRS)

Factors which influence the effects of the atmosphere on the data of remote sensing are examined. A radiative-transfer model is considered and effects of varied optical thickness of the atmosphere are investigated. Effects of varied surface albedo are discussed along with the effects of the sun angle, the effects of the scan angle, and questions regarding the atmospheric effects on the recognition performance. It is found that a multiplicative factor involving the sun angle alone is not sufficient for the correction of space data.

Turner, R. E.; Malila, W. A.; Nalepka, R. F.; Thomson, F. J.

1975-01-01

117

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

118

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

E-print Network

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

Knox, Ryan Gary

2013-01-01

119

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

SciTech Connect

The influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure is analysed along with the resulting effects on the occurrence of deep convection using National Meterological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential energy (CAPE), but also unstable planetary boundary layer (PBL). A stable PBL is observed to suppress deep convection even when CAPE is positive. Variations of SSt have a major effect on CAPE, but surface wind divergence can also affect deep convection by changing the lapse rate in the lower troposphere and humidity in the PBL. In warm SST regions, CAPE > 0 regardless of assumptions about condensate loading. When SST <27[degrees]C, CAPE layer and moisten the PBL enough to make the atmosphere neutrally stable in the mean. As a result, deep convection is generally enhanced either when SST [>=] 28[degrees]C in the absence of strong surface wind divergence or when strong surface wind convergence occurs even if SST < 27[degrees]. The anomalous suppression wind divergence or when strong surface wind convergence occurs even if SST < 27[degrees]C. The anomalous suppression of deep convection in the warm area of the equatorial west Pacific lying between the ITCZ and SPCZ is probably caused by dryness in the PBL and an inversion in that area. The seasonal cycles of deep convection and surface wind divergence are in phase with the maximum solar radiation and lead SST for one to three months in the central Pacific. The change of PBL relative humidity plays a critical role in the changeover to convective instability in this case. The seasonal change of deep convection and associated clouds seems not to have important effects on the seasonal change of local SST in the central Pacific. 37 refs., 11 figs., 1 tab.

Fu, Rong (California Institute of Technology, Pasadena, CA (United States)); Del Genio, A.D.; Rossow, W.B. (NASA/Goddard Space Flight Center, New York, NY (United States))

1994-07-01

120

Influence of atmospheric deposition on Okefenokee National Wildlife Refuge  

USGS Publications Warehouse

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

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

1995-01-01

121

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

NASA Astrophysics Data System (ADS)

Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates of surface-atmosphere CO2 fluxes from an intercomparison of atmospheric CO2 inversion models (the TransCom 3 project), which includes 16 transport models and model variants. We find an uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements, a result that is not sensitive to transport models or methodological approaches. We also find a northern land carbon sink that is distributed relatively evenly among the continents of the Northern Hemisphere, but these results show some sensitivity to transport differences among models, especially in how they respond to seasonal terrestrial exchange of CO2. Overall, carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes. Further significant constraints to our understanding of regional carbon fluxes will therefore require improvements in transport models and expansion of the CO2 observation network within the tropics.

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

2002-02-01

122

Temporal variability in emission category influence on organic matter aerosols in the Indian region  

NASA Astrophysics Data System (ADS)

The dependence of carbonaceous aerosol properties, like radiation absorption and hygroscopicity, on the emission source of origin motivate this work. The influence of emission categories, including crop residue and forest burning, biofuel combustion, brick kilns, thermal power plants, diesel transport and ``other industry'', is estimated on organic matter (OM) surface concentrations in the Indian ocean region. The approach uses general circulation model predicted OM surface concentrations during a ship cruise, identifies probable source regions for high concentration episodes using the potential source contribution function, and estimates collocated OM emissions resolved by category. Distinct source regions identified, are the Indo-Gangetic Plain during 20-30th January, 1999, and central/south India during 1-11th March, 1999. Contributing emission categories are primarily biofuel combustion (18 Gg) during 20-30th January, but a combination of forest burning (8 Gg), biofuel combustion (7 Gg) and crop residue (5 Gg) during 1-11th March. The magnitude of emission flux rather than spatial extent of an emission category, was seen to increase its influence on the receptor. This approach can be used to investigate seasonal and inter-annual variability in emission category influence on atmospheric pollutants.

Cherian, R.; Venkataraman, C.; Ramachandran, S.

2009-03-01

123

Atmospheric brown clouds: Hemispherical and regional variations in long-range transport, absorption, and radiative forcing  

Microsoft Academic Search

The study uses satellite observations, global assimilated aerosol data sets, Atmospheric Brown Clouds (ABC) observatories, a Monte Carlo aerosol-cloud-radiation model and a regional chemical transport model (STEM-2K) to characterize the spatial extent of brown clouds, regional and megacity ABC hot spots, chemical composition and the direct radiative forcing. It presents the first annual cycle of aerosol observations and forcing from

V. Ramanathan; F. Li; M. V. Ramana; P. S. Praveen; D. Kim; C. E. Corrigan; H. Nguyen; Elizabeth A. Stone; James J. Schauer; G. R. Carmichael; Bhupesh Adhikary; S. C. Yoon

2007-01-01

124

Reassessment of the Antarctic surface mass balance using calibrated output of a regional atmospheric climate model  

Microsoft Academic Search

(1) A detailed comparison of model-simulated and observed Antarctic surface mass balance (SMB) is presented, using output of a regional atmospheric climate model (RACMO2\\/ANT) for the period 1980 to 2004. All available SMB observations from Antarctica (N = 1900) are used for the comparison, except clearly erroneous observations and data which are in areas where dominant SMB patterns occur on

W. J. van de Berg; M. R. van den Broeke; C. H. Reijmer; E. van Meijgaard

2006-01-01

125

Observations and simulations of synoptic, regional, and local variations in atmospheric CO2  

E-print Network

Observations and simulations of synoptic, regional, and local variations in atmospheric CO2 Jih] Synoptic events may play an important role in determining the CO2 spatial distribution and temporal 2001, which had the most significant CO2 concentration variation in our case pool. The CO2

Collett Jr., Jeffrey L.

126

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

Microsoft Academic Search

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

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

2007-01-01

127

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

PubMed

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

Lavin, Karen S; Hageman, Kimberly J

2013-02-01

128

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

E-print Network

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

Guedel, Manuel

129

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

E-print Network

hemisphere with the Swedish 1-m Solar Telescope on 26 August 2003. The upper panel shows the filament spineSubsurface and Atmospheric Influences on Solar Activity ASP Conference Series, Vol. 383, c 2008 R and their Interrelation Y. Lin,1 S. F. Martin,2 and O. Engvold1 Abstract. The main structural components of solar

Lin, Yong

130

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

131

Atmosphere-ocean exchanges between the Canadian Regional Climate Model (CRCM) and the Gulf of Saint-Lawrence Ocean Model (GOM)  

NASA Astrophysics Data System (ADS)

Atmosphere-ocean exchanges over the Gulf of Saint-Lawrence (Canada) are investigated using an atmosphere-ocean climate simulation system developed with the Canadian Regional Climate Model (CRCM) and the Gulf of Saint-Lawrence Ocean Model (GOM). Within the ocean (atmosphere) model, the atmospheric (oceanic) fields are not calculated but are required to compute the turbulent vertical surface fluxes. Therefore, the models interact through the exchange of atmospheric and oceanic fields in an iterative process. The experience consists in the execution of three iterations by the two models over the same period of one year. Results show the ability of the CRCM-GOM system to reproduce realistic exchanges between the atmosphere and the ocean over the Gulf of Saint-Lawrence. We find that the solution of each model converges after several iterations. These results confirm the influence of turbulent fluxes during winter and of radiatives fluxes during summer on the net surface heat flux and consequently on the sea surface temperature. This study is a part of the development of a coupled ocean-ice-atmosphere modeling system for coastal waters of Eastern Canada, including the Gulf of Saint-Lawrence and the Hudson Bay, with the aim of furthering our understanding of regional-scale coastal climate processes and improving their simulations in current as well as in perturbed climate.

Charpentier, D.; Caya, D.; Saucier, F.; Laprise, R.

2003-04-01

132

Influence of stochastic sea ice parametrization on climate and the role of atmosphere-sea ice-ocean interaction.  

PubMed

The influence of a stochastic sea ice strength parametrization on the mean climate is investigated in a coupled atmosphere-sea ice-ocean model. The results are compared with an uncoupled simulation with a prescribed atmosphere. It is found that the stochastic sea ice parametrization causes an effective weakening of the sea ice. In the uncoupled model this leads to an Arctic sea ice volume increase of about 10-20% after an accumulation period of approximately 20-30 years. In the coupled model, no such increase is found. Rather, the stochastic perturbations lead to a spatial redistribution of the Arctic sea ice thickness field. A mechanism involving a slightly negative atmospheric feedback is proposed that can explain the different responses in the coupled and uncoupled system. Changes in integrated Antarctic sea ice quantities caused by the stochastic parametrization are generally small, as memory is lost during the melting season because of an almost complete loss of sea ice. However, stochastic sea ice perturbations affect regional sea ice characteristics in the Southern Hemisphere, both in the uncoupled and coupled model. Remote impacts of the stochastic sea ice parametrization on the mean climate of non-polar regions were found to be small. PMID:24842027

Juricke, Stephan; Jung, Thomas

2014-06-28

133

Atmosphere-ground modelling of freeze and thaw processes in permafrost regions  

NASA Astrophysics Data System (ADS)

The aim of this proposed project is to realistically simulate the water and energy exchange processes between atmosphere and ground in permafrost regions by using a coupled soil-atmosphere model system. The project will be focused on freezing and thawing processes of the ground, in particular permafrost degradation processes such as changes in the active layer thickness. The coupled model system consists of the non-hydrostatic mesoscale model KAMM (Karlsruhe Atmospheric Mesoscale Model) and the soil vegetation atmosphere transport (SVAT) model VEG3D, recently extended to incorporate explicit treatment of the snow cover evolution. In order to simulate the evolution of frozen ground and to address permafrost specific processes, the SVAT model has to be extended to incorporate the occurrence of frozen water. Parameterisations for processes associated with freezing and thawing, such as freezing point depression and changes in unfrozen water circulation will be included. Model validation will be performed using data sets from different permafrost sites, including monitoring data of ground temperature, soil water content and standard meteorological parameters. Model simulations will be conducted on different temporal and spatial scales, especially for comparative analyses of similar atmospheric episodes in different Arctic and Alpine regions.

Hauck, C.; Kneisel, C.; Kottmeier, C.

2003-04-01

134

The large-scale biosphere-atmosphere experiment in Amazonia: Analyzing regional land use change effects  

NASA Astrophysics Data System (ADS)

The Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) is a multi-disciplinary, multinational scientific project led by Brazil. LBA researchers seek to understand Amazonia in its global context especially with regard to regional and global climate. Current development activities in Amazonia including deforestation, logging, cattle ranching, and agriculture significantly perturb regional and global carbon budgets and the atmospheric radiation budget through both greenhouse gas inputs and the increase in atmospheric particulates generated by fires. The Brazilian Amazon currently releases about 0.2 Pg-C to the atmosphere each year as a result of net deforestation. Logging and forest fire activity are poorly quantified but certainly increase this amount by more than 10%. Fires associated with land management activities generate smoke that leads to heating of the lower atmosphere, decreases in overall cloudiness, increases in cloud lifetimes, and the suppression of rainfall. There are considerable uncertainties associated with our understanding of smoke effects. Present development trends point to agricultural intensification in the Brazilian Amazon. This intensification and the associated generation of wealth present an opportunity to enhance governance on the frontier and to minimize the damaging effects of fires.

Keller, Michael; Silva-Dias, Maria Assunção; Nepstad, Daniel C.; Silva-Andreae, Meinrat O.

135

Evaluation of a Regional Atmospheric Model Using Measurements of Surface Heat Exchange Processes from a Site in Antarctica  

Microsoft Academic Search

A regional atmospheric climate model with a horizontal grid spacing of 55 km has been used to simulate the Antarctic atmosphere during an austral summer period. ECMWF reanalyses were used to force the atmospheric\\u000aprognostic variables from the lateral boundaries. Sea surface temperatures and the sea ice mask in the model were prescribed from observations. Parameterizations of the physical processes

Nicole P. M. van Lipzig; Erik van Meijgaard; Johannes Oerlemans

1999-01-01

136

Atmosphere  

NSDL National Science Digital Library

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

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

2003-01-01

137

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

E-print Network

build a conductive channel in the gas flow and provide seed electrons, thus the discharge canInfluence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma 2014 23:18:06 #12;Influence of Penning effect on the plasma features in a non-equilibrium atmospheric

Zexian, Cao

138

Investigation of the ocean-atmosphere-continent coupling in the Gulf of Guinea and West Africa at intraseasonal timescales in boreal spring and summer with a regional atmospheric model (WRF)  

NASA Astrophysics Data System (ADS)

Using 2000-2009 satellite data (Reynolds for SST and QuikSCAT for surface winds), a strong ocean-atmosphere coupling was put in evidence in the equatorial region (northern front) of the Tropical Atlantic cold tongue, implying surface winds and sea surface temperature (SST): a cold (respectively warm) SST anomaly strengthens (weakens) southerlies between the Equator and the Guinean coast during a few days. Similar investigations with ERA-Interim and NCEP-CFSR reanalyses emphasized the significant contribution of these wind fluctuations to the triggering of the Guinean coastal rainfall in spring. In this study, mechanisms at stake behind the statistical results are investigated by using a regional atmospheric model, WRF (Weather Research and Forecasting) with horizontal resolution of 50 km for the period April-July 2006. First, the influence of the SST on the spring and summer precipitation is quantified through the analysis of the moisture flux convergence over the continent. Then, some hints of a potential feedback from the changing continental surface (under rainy conditions) over the regional atmospheric circulation are shown , likely involving the southward low-level atmospheric circulation (or Shallow Meridional Circulation), subsidence over the Gulf of Guinea and then surface southerlies again, closing an active loop of ocean-atmosphere-continent interaction.

Meynadier, R.; De Coëtlogon, G.; Leduc-Leballeur, M.; Bastin, S.; Peter, A.-C.; Janicot, S.; Bock, O.; Flamant, C.

2012-04-01

139

Protein patterning utilizing region-specific control of wettability by surface modification under atmospheric pressure  

NASA Astrophysics Data System (ADS)

Wettability control can be crucial in improving the uniformity of selective protein immobilization in high-density microarrays. In this study, we propose an atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD)-based method in conjunction with photolithography to implement region-specific control of wettability on Si substrate. The proposed PECVD method under atmospheric pressure condition would be a useful alternative of conventional reactive plasma-based treatments methods requiring vacuum condition for uniform protein patterning. Layers with dissimilar wettability and roughness prepared by AP-PECVD process using tetraethoxysilane (TEOS) or TEOS-O2 as precursors could realize uniform protein patterning in a micrometer-scale.

Lee, Donghee; Kwon, Min-Sung; Hyun, Ji-Chul; Jun, Chang-Duk; Chung, Euiheon; Yang, Sung

2013-09-01

140

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

E-print Network

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

Kachakhidze, M K; Kachakhidze, N K

2012-01-01

141

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

142

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

143

Areas where solar-terrestrial coupling may influence or be influenced by the middle atmosphere  

NASA Technical Reports Server (NTRS)

The nature of the wave interactions, particularly those induced by transient solar and geomagnetic phenomena is discussed. Solar activity which includes modulations of galactic cosmic ray flux reaching Earth is discussed. Coupling processes involving charged particles and atmospheric electric structure are presented.

Goldberg, R. A.

1979-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

146

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

E-print Network

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

Alexander Bolonkin

2008-01-31

147

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

149

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

PubMed

The incidence of suicide attempts [Deliberate Self Harm (DSH); ICD-10: X60-X84] and psychotic attacks (PsA; ICD-10, F20-F29) in association with atmospheric states, typical for areas close to big deserts, was analyzed. A retrospective study is based on the 4,325 cases of DSH and PsA registered in the Mental Health Center (MHC) of Ben-Gurion University (Be'er-Sheva, Israel) during 2001-2003. Pearson and Spearman test correlations were used; the statistical significance was tested at p?influence of temperature and humidity on suicide attempts (N(SU)) and psychotic attacks (N(PS)) was weakly pronounced (p?>?0.1). Correlation coefficients between N(SU) and N(PS) and speed WS of westerly wind reaches 0.3 (p??0.09). Variations in easterly wind direction WD influence N(SU) and N(PS) values (p??0.3). Obviously ,in transition areas located between different regions ,the main role of air streams in meteorological-biological impact can scarcely be exaggerated. An unstable balance in the internal state of a weather-sensitive person is disturbed when the atmospheric state is changed by specific desert winds, which can provoke significant perturbations in meteorological parameters. Results indicate the importance of wind direction, defining mainly the atmospheric situation in semi-arid areas: changes in direction of the easterly wind influence N(SU) and N(PS), while changes in WS are important for mental health under westerly air streams. Obviously, N(SU) and N(PS) are more affected by the disturbance of weather from its normal state, for a given season, to which the local population is accustomed, than by absolute values of meteorological parameters. PMID:20668888

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

2011-05-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

152

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

153

Regional climate and atmospheric circulation controls on the discharge of two British rivers, 1974–97  

Microsoft Academic Search

Summary ¶The dependence of the discharge (Q) of two contrasting UK rivers (Itchen, Ewe) on concurrent and lagged regional climate (RC) and atmospheric circulation (AC) variations was assessed over the period 1974–97. RC variables used were temperature and precipitation; the AC indicators used were 850?hPa water vapour flux anomalies (VF) at five western European stations, and the Arctic (AOI) and

I. D. Phillips; G. R. McGregor; C. J. Wilson; D. Bower; D. M. Hannah

2003-01-01

154

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

SciTech Connect

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

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

2011-01-01

155

Carbonaceous particles in the atmosphere and precipitation of the Nam Co region, central Tibet.  

PubMed

A continuous air and precipitation sampling for carbonaceous particles was conducted in a field observatory beside Nam Co, Central Tibetan Plateau during July of 2006 through January of 2007. Organic carbon (OC) was the dominant composition of the carbonaceous particles both in the atmosphere (1660 ng/m3) and precipitation (476 ng/g) in this area, while the average elemental carbon (BC) concentrations in the atmosphere and precipitation were only 82 ng/m3 and 8 ng/g, respectively. Very high OC/BC ratio suggested local secondary organic carbon could be a dominant contribution to OC over the Nam Co region, while BC could be mainly originated from Southern Asia, as indicated by trajectory analysis and aerosol optical depth. Comparison between the BC concentrations measured in Lhasa, those at "Nepal Climate Observatory at Pyramid (NCO-P)" site on the southern slope of the Himalayas, and Nam Co suggested BC in the Nam Co region reflected a background with weak anthropogenic disturbances and the emissions from Lhasa might have little impact on the atmospheric environment here, while the pollutants from the Indo-Gangetic Basin of Southern Asia could be transported to the Nam Co region by both the summer monsoon and the westerly. PMID:21235163

Ming, Jing; Xiao, Cunde; Sun, Junying; Kang, Shichang; Bonasoni, Paolo

2010-01-01

156

The influence of timing error on performance of optical pulse PPM system in atmospheric turbulence  

NASA Astrophysics Data System (ADS)

With the avalanche photodiode (APD) as the receiver, we have studied the timing error influence on performance of the optical pulse PPM system after analyzing the channel model of the atmospheric laser communication, and respectively obtained the relationship between the normalized timing error and PWE in the strong and weak turbulent environment. In addition, we obtained the influences of parameters such as the scintillation index, APD average gain and the levels of PPM modulation on performance of the optical pulse PPM system by simulation when there are timing errors in the system.

Fan, Wei; Yang, Xiao-li; E., Yu

2011-06-01

157

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

Microsoft Academic Search

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

Rym Msadek; Claude Frankignoul

2009-01-01

158

Influence of soil moisture on sulphur oxidation in brown earth soils exposed to atmospheric pollution  

Microsoft Academic Search

Laboratory studies were conducted to determine the influence of soil moisture on S oxidation in atmospheric-polluted brown earth soils. Elemental S was oxidized to sulphate over a wide range of soil moisture treatments (10%–60% w\\/w), but occurred optimally at around 40%–50% soil moisture content (0.08 MPa). Thiosulphate and tetrathionate were found only in soils incubated at low moisture contents. S-oxidation

Wendy Nevell; M. Wainwright

1987-01-01

159

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

PubMed

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

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

2013-10-22

160

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

PubMed Central

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

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

2013-01-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

162

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

165

Geographical Patterns in Cyanobacteria Distribution: Climate Influence at Regional Scale  

PubMed Central

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

Pitois, Frederic; Thoraval, Isabelle; Baures, Estelle; Thomas, Olivier

2014-01-01

166

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

PubMed

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

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

167

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

168

Near-surface air temperature retrieval from satellite images and influence by wetlands in urban region  

NASA Astrophysics Data System (ADS)

Near-surface air temperature (NSAT) directly reflects the thermal conditions above the ground and has been considered as a relevant indicator of resident health in urban regions. The rapid retrieval of NSAT data is necessary to assess urban environments. In this paper, a method of NSAT retrieval is developed that employs Landsat Thematic Mapper images using an Energy Balance Bowen Ratio model. This model is established based on the energy balance over land and the Bowen ratio. The degree of retrieval error obtained when using this model is determined on the basis of a comparison with the observed values obtained from weather stations; the mean error is approximately 2.21 °C. Moreover, the spatial relationship between NSAT and urban wetlands is analyzed using Geographical Information System technology. The results show that wetlands have an obvious influence on atmospheric temperature and that this influence decreases as the distance from the wetland increases. When that distance is less than 300 m, its influence on the NSAT is significant.

Hou, Peng; Chen, Yunhao; Qiao, Wang; Cao, Guangzhen; Jiang, Weiguo; Li, Jing

2013-01-01

169

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

Microsoft Academic Search

The effects of air pollution on lichen biodiversity (LB) were monitored in Liguria (northwest Italy). A systematic sampling strategy was adopted in order to avoid the influence of spatial autocorrelation on the results. An eight LB class scale permitted to point out the levels of naturality\\/alteration in the region. The comparison of these results with the ones obtained by mean

Paolo Giordani; Giorgio Brunialti; Dario Alleteo

2002-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

172

Influence of mechanical activation on decomposition of a chalcopyrite-pyrite mixture in an oxidizing atmosphere  

Microsoft Academic Search

The influence of the addition of pyrite and mechanical activation on an oxidative decomposition of chalcopyrite was studied. The course of the thermoanalytical curves and X-ray identification of the products showed that addition of pyrite affects mainly the endothermic processes taking place in region of low temperatures but does not significantly influence the temperature of CuSO4 formation and its content

K. Tká?ová; P. Baláž; T. A. Korneva

1988-01-01

173

Influence of Benzene on Aerosol- and Gas-Phase Chemistry in Haze Analog Atmospheres  

NASA Astrophysics Data System (ADS)

Benzene (C6H6) has been observed in the haze atmospheres of Saturn and Jupiter by the Infrared Space Observatory [1] and in the atmosphere of Titan, most recently during the Cassini mission by the Ion and Neutral Mass Spectrometer [2,3] and the Composite Infrared Spectrometer [4]. Photochemical reactions involving benzene may influence polycyclic aromatic hydrocarbon formation, aerosol formation, and the radiative balance of planetary atmospheres. We measure the influence of benzene on a model system, Titan analog particles, in the laboratory by photolyzing CH4/N2 gas mixtures infused with ppm-levels of C6H6 using a deuterium lamp (115-400 nm). We measure the chemical composition of the aerosol-phase products and gas-phase products using aerosol mass spectrometry and proton-transfer ion-trap mass spectrometry, respectively. We measure the optical properties of the aerosol-phase products at 532 nm using cavity ring-down aerosol extinction spectroscopy. These studies are compared to previous studies [5,6] of Titan analog particles formed by methane photolysis. [1] Bezard B. et al. (2001) Icarus, 154, 492-500. [2] Waite, J. H. et al. (2007) Science, 316, 870-875. [3] Vuitton, V. et al. (2008) JGR, 113, E05007. [4] Coustenis, A. et al. (2007) Icarus, 189, 35-62. [5] Hasenkopf, C.A. et al. (2010) Icarus, 207, 903-913. [6] Trainer, M. G. et al. (2012) Astrobiology, 12, 315-326.

Yoon, Y. H.; Horst, S. M.; Li, R.; Barth, E. L.; Trainer, M. G.; De Gouw, J. A.; Tolbert, M. A.

2012-12-01

174

Influence of thermal deformations of resonators on propagation properties of laser annular beams through turbulent atmosphere  

NASA Astrophysics Data System (ADS)

Based on the laser field from a positive confocal unstable resonator, considering the influence of thermal distortion of the internal resonator mirror on the annular beam, the propagation characteristics of the annular beam through turbulent atmosphere are investigated by means of the fast Fourier transform algorithm (FFT). The intensity distributions of the output laser far-field are obtained to analyze the propagation characteristics of laser annular beam through the turbulent atmosphere, which is a function about different propagation distances. The results show that the peak intensity of the laser pattern becomes depressed and the spread of the far field diagram patterns is broadened under the increasing of the transmission distance and the thermal distortion of the laser resonator. ?-parameter and strehl ratio are introduced to estimate the annular beam quality characteristics. It is found that the annular beam through strong turbulence influences much less obviously than the annular beam through weak turbulence on the quality characteristics with thermal distortion. In the same atmospheric conditions with a certain distance, the greater the mirror thermal distortion is, the worse the annular beam quality characteristics is.

Peng, Yufeng; Peng, Fang; Han, Junpeng

2013-02-01

175

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

PubMed Central

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

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

2013-01-01

176

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

SciTech Connect

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

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

2012-03-20

177

Modeling interactions of aircraft emissions with global and regional atmospheric chemistry and climate  

NASA Astrophysics Data System (ADS)

Aircraft engines emit a variety of chemical compounds that affect atmospheric chemistry and climate. In the research presented here, we have addressed three different issues related to aircraft emissions. The first phase of the research has two parts. In the first part, we have analyzed the effects of potential fleets of aircraft on atmospheric ozone concentrations. We have used a zonally-averaged two-dimensional chemical-transport model to parametrically evaluate the full envelop of effects from possible fleets of subsonic or near supersonic aircraft, that would fly extensively in the upper troposphere and lower stratosphere (UTLS) region. The maximum effect from the new set of parametric studies on Northern Hemisphere total column ozone change is seen to be -0.82%, implying that, for certain designs and potential use, fleets of aircraft could raise concerns about global ozone depletion. In the second part, our narrowband radiative transfer model is used to investigate how aircraft emissions impact on the net radiative forcing driving changes in climate. A series of sensitivity studies are performed and the results show that there should be little concern about climate effects due to the projected fleets resulting from effects on atmospheric water vapor and ozone. In the last phase, we have focused on analyzing the impact of aircraft flights from Chicago O'Hare and Midway Airports on the regional air quality of the region using the Community Multiscale Air Quality Model (CMAQ) system. Our results suggest that the aircraft traffic at the Chicago O'Hare and Midway Airports do not contribute significantly to ground level ozone pollution in the Chicago area, and are much smaller than the effects due to other emissions such as those from vehicular traffic.

Dutta, Mayurakshi

178

Tropical cyclones in a regional coupled ocean-atmosphere model of the South Pacific Convergence Zone  

NASA Astrophysics Data System (ADS)

The South Pacific Convergence Zone (SPCZ) is the most powerful convective machine of the Southern Hemisphere. Extreme weather and water resources of numerous vulnerable islands depend on its behavior. In particular, the SPCZ experiences about 15% of global annual cyclone occurrence. Yet, understanding the coupled ocean-atmosphere dynamics of the SPCZ is a challenge that is still to be met, especially in view of the strong known biases of climate models in this region. Tropical cyclone development and fate are intrinsically linked to air-sea coupling as they derive their energy from air-sea heat and moisture fluxes. Most notably, as cyclones develop, they induce sea surface cooling on their track that provides a negative feedback on their intensity. The objective of the present study is to quantify the capacity of air-sea coupling to control cyclonic intensity in the SPCZ. It fills a gap in the current modeling literature between coarse resolution coupled climate models and short-term studies. For this study, we implemented a regional coupled model of the SPCZ at 35 km resolution, based on the mesoscale atmospheric model WRF (Weather Research and Forecast) and oceanic model ROMS (Regional Oceanic Modeling System). Interannual boundary forcing is applied in a 10-year long simulation. The SPCZ behavior in the coupled system is shown to be realistic in terms of large-scale circulation, and patterns and magnitude of precipitation and air-sea fluxes. The surface drag coefficients appear among the most sensitive parameters in the coupled system. The residual coupling effect is analyzed through comparison between the coupled simulation and an uncoupled atmospheric simulation. Significant statistical changes induced by coupling as expressed in spatial distribution, seasonal variability and intensity distribution are evidenced in this comparison at both cyclonic and climatological scales. We also estimate the changes in stochastic processes that affect the interannual variability of cyclonic activity.

Jullien, S.; Marchesiello, P.; Menkes, C.; Lefevre, J.; Lengaigne, M.

2012-12-01

179

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

180

Premixed Atmosphere and Convection Influences on Flame Inhibition and Combustion (PACIFIC)  

NASA Technical Reports Server (NTRS)

Under NASA-Lewis Grant NAG3-1611, starting date 6/1/94, a three-year experimental and theoretical study of the effects of ambient atmosphere on the properties of flame spread over thin and thick solid fuel beds has been initiated. In particular the effect of the type of inert gas, which affects the Lewis numbers of fuel and oxidant, and the effect of the addition of sub-flammability-limit concentrations of gaseous fuels to the oxidizing atmosphere will be studied. The effect of convection will be studied through one-g and mu g experiments with and without a forced flow. Moreover, the influence of thermal radiation, whose effect is known to be markedly different depending on the convection level, will be addressed.

Ronney, Paul D.

1995-01-01

181

Titan's atmosphere from Voyager infrared observations. I - The gas composition of Titan's equatorial region  

Microsoft Academic Search

After inferring minor atmospheric-constituent abundances in Titan's equatorial region from Voyager 1 IR spectra, a stratospheric temperature profile is derived. An analysis of three different sections has yielded stratospheric mole fractions for C2H2, C2H4, C2H6, C3H4, C3H8, C4H2, HCN, and CO2; an altitude-dependent CO2 profile has been tested against observations, but no conclusive data on vertical distribution could be extracted.

A. Coustenis; B. Bezard; D. Gautier

1989-01-01

182

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

NASA Astrophysics Data System (ADS)

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

Deng, Jinping; Ji, Xiaoling

2014-05-01

183

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

E-print Network

and an increase in surface downward55 shortwave radiation flux during summer due to diminished atmospheric International Centre for Theoretical Physics Regional Climate Model Version 4. The Great51 Lakes dampen

Wisconsin at Madison, University of

184

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

185

Human Influence on the Atmospheric Vertical Temperature Structure: Detection and Observations  

PubMed

Recent work suggests a discernible human influence on climate. This finding is supported, with less restrictive assumptions than those used in earlier studies, by a 1961 through 1995 data set of radiosonde observations and by ensembles of coupled atmosphere-ocean simulations forced with changes in greenhouse gases, tropospheric sulfate aerosols, and stratospheric ozone. On balance, agreement between the simulations and observations is best for a combination of greenhouse gas, aerosol, and ozone forcing. The uncertainties remaining are due to imperfect knowledge of radiative forcing, natural climate variability, and errors in observations and model response. PMID:8895461

Tett; Mitchell; Parker; Allen

1996-11-15

186

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

NASA Technical Reports Server (NTRS)

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.

Small, Eric; Lakshmi, Venkat

2005-01-01

187

Simulation of a persistent snow storm over southern China with a regional atmosphere-ocean coupled model  

NASA Astrophysics Data System (ADS)

A regional atmosphere-ocean coupled model, RegCM3-POM, was developed by coupling the regional climate model (RegCM3) with the Princeton Ocean Model (POM). The performance of RegCM3-POM in simulating a persistent snow storm over southern China and the impact of the Madden-Julian oscillation (MJO) on this persistent snow storm were investigated. Compared with the stand-alone RegCM3, the coupled model performed better at reproducing the spatial-temporal evolution and intensity of the precipitation episodes. The power spectral analysis indicated that the coupled model successfully captured the dominant period between 30 and 60 days in the precipitation field, leading to a notable improvement in simulating the magnitude of intraseasonal precipitation variation, and further in enhancing the intensity of the simulated precipitation. These improvements were mainly due to the well-simulated low-frequency oscillation center and its eastward propagation characteristics in each MJO phase by RegCM3-POM, which improved the simulations of MJO-related low-frequency vertical motions, water vapor transport, and the deep inversion layer that can directly influence the precipitation event and that further improved the simulated MJO-precipitation relationship. Analysis of the phase relationship between convection and SST indicated that RegCM3-POM exhibits a near-quadrature relation between the simulated convection and SST anomalies, which was consistent with the observations. However, such a near-quadrature relation was not as significant when the stand-alone RegCM3 was used. This difference indicated that the inherent coupled feedback process between the ocean and atmosphere in RegCM3-POM played an important part in reproducing the features of the MJO that accompanied the snow storm.

Liao, Zhijie; Zhang, Yaocun

2013-03-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

189

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

NASA Astrophysics Data System (ADS)

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

Tim, Nele; Zorita, Eduardo; Hünicke, Birgit

2014-05-01

190

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

SciTech Connect

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

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

1994-02-01

191

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

192

The Influence of North American Carbon Flux Spatial Distribution on the Temporal Variability of Atmospheric Carbon Dioxide  

Microsoft Academic Search

A small subset of biospheric model estimates of net ecosystem exchange (NEE) are used to assess the ability of the North American CO2 sampling network to detect regional spatial variability (i.e., 1° x 1°) in land-atmospheric carbon flux. The atmospheric signal at continuous observation locations operating in 2004 resulting from biospheric model derived NEE is quantified using the WRF-STILT atmospheric

D. N. Huntzinger; S. Gourdji; A. M. Michalak

2009-01-01

193

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

NASA Astrophysics Data System (ADS)

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

Berresheim, Harald

194

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...

195

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

196

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

197

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

NASA Astrophysics Data System (ADS)

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

Moritzer, E.; Leister, C.

2014-05-01

198

Influence of Equatorial Diatom Processes on Si Deposition and Atmospheric CO(2) Cycles at Glacial\\/Interglacial Timescales  

Microsoft Academic Search

The causes of the glacial cycle remain unknown, although the primary driver is changes in atmospheric CO(2), likely controlled by the biological pump and biogeochemical cycles. The two most important regions of the ocean for exchange of CO(2) with the atmosphere are the equatorial Pacific and the Southern Ocean ( SO), the former a net source and the latter a

R. C. Dugdale; M. Lyle; F. P. Wilkerson; Fei Chai; R. T. Barber; T.-H. Peng

2004-01-01

199

Influence of equatorial diatom processes on Si deposition and atmospheric CO2 cycles at glacial\\/interglacial timescales  

Microsoft Academic Search

The causes of the glacial cycle remain unknown, although the primary driver is changes in atmospheric CO2, likely controlled by the biological pump and biogeochemical cycles. The two most important regions of the ocean for exchange of CO2 with the atmosphere are the equatorial Pacific and the Southern Ocean (SO), the former a net source and the latter a net

R. C. Dugdale; M. Lyle; F. P. Wilkerson; F. Chai; R. T. Barber; T.-H. Peng

2004-01-01

200

Local Atmospheric Wind Hazards to Entry, Descent and Landing Operations of the Mars Exploration Rover Mission as Predicted by the Mars Regional Atmospheric Modeling System  

Microsoft Academic Search

The entry, descent and landing (EDL) phases of the Mars Exploration Rover are sensitive to the wind, particularly below one scale height. The Mars Regional Atmospheric Modeling System is used to predict the local meteorology of high priority landing sites at horizontal scales of O(1 km) and vertical scales of O(10-100 m). The results show that sites located in highly

S. C. Rafkin

2002-01-01

201

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

202

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

203

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

204

Atmospheric Transport of Arid Aerosol from Desert Regions of Central Asia  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

205

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

206

Characteristics of modern atmospheric dust deposition in snow in the Mt. Yulong region, southeastern Tibetan Plateau  

NASA Astrophysics Data System (ADS)

We evaluated the concentration, size and distribution, and temporal variation of insoluble dust micro-particles in the snow, rainfall and water taken from the areas surrounding the Mt. Yulong to define the characteristics of modern atmospheric dust deposition and the contributions of different dust sources. The mean mass concentration (4511 ?g kg-1) of micro-particles with 0.57 < d < 26 ?m, and the diameter (11.5 ?m) of dust contained in the water bodies of the Mt. Yulong are roughly similar to those observed in other sites, implying that dust is primarily supplied through short-range transport from proximal source regions (several or hundreds of km distances). The mean mass concentrations of micro-particles with 0.57 < d < 26 ?m is lower in the rainfall than in the snow and the river water, suggesting the rain water is an ideal source/carrier for detecting the characteristics of modern atmospheric micro-particles. Volume size distributions of micro-particles in the snow and water showed single modal structures having volume median diameters from 3 to 26 ?m. Number concentrations of micro-particles in the snow were higher than that in the rainfall, the river water contains the least amount of micro-particles. Vertical profiles of the snowpits show that there is a strong lateral correlation among the dust peaks, indicating a regional uniformity of dust deposition and suitability of snow analysis for dust deposition. In addition, the bare rock of snow-free terrain in the Mt. Yulong region and the mineral particles from local rock weathering are also important sources for the dust deposition.

Niu, Hewen; He, Yuanqing; Lu, Xixi; Dong, Zhiwen; Zhao, Guoyong; Zhang, Tao; Du, Jiankuo

2014-11-01

207

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

NASA Astrophysics Data System (ADS)

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

Wilcox, L.; Highwood, E.

2013-12-01

208

Mainz Isoprene Mechanism 2 (MIM2): an isoprene oxidation mechanism for regional and global atmospheric modelling  

NASA Astrophysics Data System (ADS)

We present an oxidation mechanism of intermediate size for isoprene (2-methyl-1,3-butadiene) suitable for simulations in regional and global atmospheric chemistry models, which we call MIM2. It is a reduction of the corresponding detailed mechanism in the Master Chemical Mechanism (MCM v3.1) and intended as the second version of the well-established Mainz Isoprene Mechanism (MIM). Our aim is to improve the representation of tropospheric chemistry in regional and global models under all NOx regimes. We evaluate MIM2 and re-evaluate MIM through comparisons with MCM v3.1. We find that MIM and MIM2 compute similar O3, OH and isoprene mixing ratios. Unlike MIM, MIM2 produces small relative biases for NOx and organic nitrogen-containing species due to a good representation of the alkyl and peroxy acyl nitrates (RONO2 and RC(O)OONO2). Moreover, MIM2 computes only small relative biases with respect to hydrogen peroxide (H2O2), methyl peroxide (CH3OOH), methanol (CH3OH), formaldehyde (HCHO), peroxy acetyl nitrate (PAN), and formic and acetic acids (HCOOH and CH3C(O)OH), being always below ?6% in all NOx scenarios studied. Most of the isoprene oxidation products are represented explicitly, including methyl vinyl ketone (MVK), methacrolein (MACR), hydroxyacetone and methyl glyoxal. MIM2 is mass-conserving with respect to carbon, including CO2 as well. Therefore, it is suitable for studies assessing carbon monoxide (CO) from biogenic sources, as well as for studies focused on the carbon cycle. Compared to MIM, MIM2 considers new species like acetaldehyde (CH3CHO), propene (CH2=CHCH3) and glyoxal (CHOCHO) with global chemical production rates for the year 2005 of 7.3, 9.5 and 33.8 Tg/yr, respectively. Our new mechanism is expected to substantially improve the results of atmospheric chemistry models by more accurately representing the interplay between atmospheric chemistry, transport and deposition, especially of nitrogen reservoir species. MIM2 allows regional and global models to easily incorporate new experimental results on the chemistry of organic species.

Taraborrelli, D.; Lawrence, M. G.; Butler, T. M.; Sander, R.; Lelieveld, J.

2008-07-01

209

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

NASA Astrophysics Data System (ADS)

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).

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

2009-07-01

210

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

SciTech Connect

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

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

1993-10-01

211

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

212

Regional inversion of CO2 ecosystem fluxes from atmospheric measurements: reliability of the uncertainty estimates  

NASA Astrophysics Data System (ADS)

The Bayesian framework of CO2 flux inversions permits estimates of the retrieved flux uncertainties. Here, the reliability of these theoretical estimates is studied through a comparison against the misfits between the inverted fluxes and independent measurements of the CO2 Net Ecosystem Exchange (NEE) made by the eddy covariance technique at local (few hectares) scale. Regional inversions at 0.5° resolution are applied for the western European domain where ~ 50 eddy covariance sites are operated. These inversions are conducted for the period 2002-2007. They use a mesoscale atmospheric transport model, a prior estimate of the NEE from a terrestrial ecosystem model and rely on the variational assimilation of in situ continuous measurements of CO2 atmospheric mole fractions. Averaged over monthly periods and over the whole domain, the misfits are in good agreement with the theoretical uncertainties for prior and inverted NEE, and pass the chi-square test for the variance at the 30% and 5% significance levels respectively, despite the scale mismatch and the independence between the prior (respectively inverted) NEE and the flux measurements. The theoretical uncertainty reduction for the monthly NEE at the measurement sites is 53% while the inversion decreases the standard deviation of the misfits by 38%. These results build confidence in the NEE estimates at the European/monthly scales and in their theoretical uncertainty from the regional inverse modelling system. However, the uncertainties at the monthly (respectively annual) scale remain larger than the amplitude of the inter-annual variability of monthly (respectively annual) fluxes, so that this study does not engender confidence in the inter-annual variations. The uncertainties at the monthly scale are significantly smaller than the seasonal variations. The seasonal cycle of the inverted fluxes is thus reliable. In particular, the CO2 sink period over the European continent likely ends later than represented by the prior ecosystem model.

Broquet, G.; Chevallier, F.; Bréon, F.-M.; Kadygrov, N.; Alemanno, M.; Apadula, F.; Hammer, S.; Haszpra, L.; Meinhardt, F.; Morguí, J. A.; Necki, J.; Piacentino, S.; Ramonet, M.; Schmidt, M.; Thompson, R. L.; Vermeulen, A. T.; Yver, C.; Ciais, P.

2013-09-01

213

Regional inversion of CO2 ecosystem fluxes from atmospheric measurements: reliability of the uncertainty estimates  

NASA Astrophysics Data System (ADS)

The Bayesian framework of CO2 flux inversions permits estimates of the retrieved flux uncertainties. Here, the reliability of these theoretical estimates is studied through a comparison against the misfits between the inverted fluxes and independent measurements of the CO2 Net Ecosystem Exchange (NEE) made by the eddy covariance technique at local (few hectares) scale. Regional inversions at 0.5° resolution are applied for the western European domain where ~ 50 eddy covariance sites are operated. These inversions are conducted for a 6-yr period (2002-2007). They use a mesoscale atmospheric transport model, a prior estimate of the NEE from a terrestrial ecosystem model and rely on the variational assimilation of in situ continuous measurements of CO2 atmospheric mole fractions. The misfits averaged over monthly periods and over the whole domain, are in good agreement with the theoretical uncertainties for prior (respectively inverted) NEE, with positive chi-square tests for the variance at the 2% (respectively 20%) significance levels, despite the scale mismatch and the independence between the prior (respectively inverted) NEE and the flux measurements. The theoretical uncertainty reduction for the monthly NEE at the measurement sites is 53% while the inversion actually decreases the standard deviation of the misfits by as much as 38%. These results build confidence in the NEE estimates at the European/monthly scales and in their theoretical uncertainty from the regional inverse modeling system. However, the uncertainties at the monthly (respectively annual) scale remain larger than the amplitude of the inter-annual variability of monthly (respectively annual) fluxes, so that there is a low confidence in the inter-annual variations. The uncertainties at the monthly scale are significantly smaller than the seasonal variations. The seasonal cycle of the inverted fluxes is thus reliable. In particular, the CO2 sink period over the European continent likely ends later than represented by the ecosystem model.

Broquet, G.; Chevallier, F.; Bréon, F.-M.; Alemanno, M.; Apadula, F.; Hammer, S.; Haszpra, L.; Meinhardt, F.; Necki, J.; Piacentino, S.; Ramonet, M.; Schmidt, M.; Thompson, R. L.; Vermeulen, A. T.; Yver, C.; Ciais, P.

2013-03-01

214

Regional assessment of atmospheric organic and black carbon in South Africa  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

215

Dynamic coupling of regional atmosphere to biosphere in the new generation regional climate system model REMO-iMOVE  

NASA Astrophysics Data System (ADS)

The main objective of this study is the coupling of the regional climate model REMO to a 3rd generation land surface scheme and the evaluation of the new model version of REMO, called REMO with interactive MOsaic-based VEgetation: REMO-iMOVE. Attention is paid to the documentation of the technical aspects of the new model constituents and the coupling mechanism. We compare simulation results of REMO-iMOVE and of the reference version REMO2009, to investigate the sensitivity of the regional model to the new land surface scheme. An 11 yr climate model run (1995-2005), forced with ECMWF ERA-Interim lateral boundary conditions, over Europe in 0.44° resolution of both model versions was carried out, to represent present day European climate. The result of these experiments are compared to multiple temperature, precipitation, heat flux and leaf area index observation data, to determine the differences in the model versions. The new model version has further the ability to model net primary productivity for the given plant functional types. This new feature is thoroughly evaluated by literature values of net primary productivity of different plant species in European climatic regions. The new model version REMO-iMOVE is able to model the European climate in the same quality as the parent model version REMO2009 does. The differences in the results of the two model versions stem from the differences in the dynamics of vegetation cover and density and can be distinct in some regions, due to the influences of these parameters to the surface heat and moisture fluxes. The modeled inter-annual variability in the phenology as well as the net primary productivity lays in the range of observations and literature values for most European regions. This study also reveals the need for a more sophisticated soil moisture representation in the newly developed model version REMO-iMOVE to be able to treat the differences in plant functional types. This gets especially important if the model will be used in dynamic vegetation studies.

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

2013-05-01

216

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

PubMed

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

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

2014-01-01

217

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

NASA Astrophysics Data System (ADS)

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.

Bari, M.; Kindzierski, W.

2012-12-01

218

Intercomparsion of regional biases and doubled CO2-sensitivity of coupled atmosphere-ocean general circulation model experiments  

Microsoft Academic Search

We compared regional biases and transient doubled CO2 sensitivities of nine coupled atmosphere-ocean general circulation models (GCMs) from six international climate modeling\\u000a groups. We evaluated biases and responses in winter and summer surface air temperatures and precipitation for seven subcontinental\\u000a regions, including those in the 1990 Intergovernmental Panel on Climate Change (IPCC) Scientific Assessment. Regional biases\\u000a were large and exceeded

T. G. F. Kittel; F. Giorgi; G. A. Meehl

1997-01-01

219

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

USGS Publications Warehouse

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

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

1998-01-01

220

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

PubMed

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

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

2014-07-01

221

Observations of D-region structure and atmospheric tides with PFISR during active aurora  

NASA Astrophysics Data System (ADS)

We report on combined spectral measurements of the D-region ionosphere and the polar summer mesosphere and lower thermosphere performed on 9 June 2007 with the 450 MHz Poker Flat Incoherent Scatter Radar (PFISR) under active auroral conditions. Observations during the first 7 h occurred at nighttime and revealed strong temporal correlations between enhanced auroral precipitation, the occurrence of polar mesosphere summer echoes (PMSE), and enhanced electron densities (Ne) extending to much lower altitudes than the previously reported at these latitudes without the presence of a polar cap absorption (PCA) event. PMSE and lower D-region echoes most often occurred together and PMSE were more often visible to PFISR before the Ne of the D-region was sufficiently high to be detected. These measurements also enabled definition of high precision horizontal winds (errors of ) in the altitude range, which has previously been possible only with MF and HF radars, with the Arecibo 430 MHz IS radar (ISR), or with other ISRs during PCA events. This observing technique allowed for of almost continuous measurements of the meridional and zonal wind fields and thus permitted the measurements of atmospheric tides over this large altitude range. We determine amplitude and phase for both the diurnal and semi-diurnal tides showing the latter to be stronger as expected at these latitudes. We also present observations of a gravity wave during a quiet period indicating that PFISRs sensitivity is sufficiently high to obtain reliable spectral information even when electron densities are not enhanced by aurora or a PCA event and are as low as . These results show the capabilities of PFISR to study the neutral dynamics in the polar D-region and mesosphere and lower thermosphere (MLT) over an unprecedented altitude range.

Janches, D.; Fritts, D. C.; Nicolls, M. J.; Heinselman, C. J.

2009-05-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

223

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

SciTech Connect

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.

Hiroyuki Enomoto; Atsumu Ohmura (Swiss Federal Inst. of Tech., Zurich (Switzerland))

1990-06-15

224

[Influence of atmospheric transport on air pollutant levels at a mountain background site of East China].  

PubMed

Transport characteristics of air pollutants transported to the background atmosphere of East China were investigated using HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) 4.8 model driven by NCEP reanalysis data during June 2011 to May 2012. Based on the air pollutants monitoring data collected at the National atmospheric background monitoring station (Wuyishan station) in Fujian Province, characteristics of different clustered air masses as well as the origins of highly polluted air masses were further examined. The results showed that 65% of all the trajectories, in which air masses mainly passed over highly polluted area of East China, Jiangxi province and upper air in desert areas of Northwest China, carried polluted air to the station, while the rest of trajectories (35%) with air masses originated from ocean could effectively remove air pollutants at the Wuyishan station. However, the impact on the air pollutants for each air mass group varied with seasons. Elevated SO2 concentrations observed at the background station were mainly influenced by coal burning activities in Northern China during heating season. The high CO concentrations were likely associated with the pollutants emission in the process of coal production and consumption in Anhui province. The elevated NO(x), O3, PM10 and PM2.5 concentrations were mostly impacted by East China with high levels of air pollutants. PMID:25338354

Su, Bin-Bin; Xu, Ju-Yang; Zhang, Ruo-Yu; Ji, Xian-Xin

2014-08-01

225

Influence of the solar activity on the green atmospheric airglow emission  

NASA Astrophysics Data System (ADS)

Middle latitude airglow emissions are sensitive to thermal and helio-geophysical conditions including atmospheric gravity waves vertical perturbations and conductivity seismic activity etc The investigation of their variability presents an effective method of studying physical and physico-chemical properties of the middle and upper Earth s atmosphere The nighttime airglow emissions from the upper mesosphere and lower thermosphere are dominantly produced through reactions driven by the recombination of atomic oxygen to its molecular form Intensities of the O 1 S 5577 AA emission has been observed at Stara Zagora Bulgaria by zenith tilting photometer during the period of July 2001 -- May 2002 23 rd Solar Cycle maximum Measurements from 143 nights have been used to analyse the nocturnal day to day and seasonal variations of the oxygen green emission line In order to avoid the dynamical influence of tides on the daily variations monthly mean values have been derived from averaged night intensities taken in 2 hour time interval 21-23UT The same analysis has been conducted using data measured at Irkutsk Russia at 50 r latitude and 70 r difference in geographic longitude in the same time period Semiannual oscillations have been well outlined in the two emissions showing equinoctial maxima The large green line intensity observed at Irkutsk in December and partly in January is associated with the stratospheric warming Correlation between green line intensities relative sunspot number and F10 7 radio emission

Stoeva, P.; Mikhalev, A.; Benev, B.; Medvedeva, I.; Mishin, V.

226

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

SciTech Connect

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

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

1997-11-01

227

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

NASA Astrophysics Data System (ADS)

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 ?g N m-3, and PM10 concentrations averaged 249.2 ?g 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.

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

228

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

NASA Astrophysics Data System (ADS)

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 ?g N m-3, and PM10 concentrations averaged 249.2 ?g 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.

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

229

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

231

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

232

Water resources of the South Asian region in a warmer atmosphere  

NASA Astrophysics Data System (ADS)

The global mean surface temperature may rise by about 0.3° C per decade during the next few decades as a result of anthropogenic greenhouse gas emissions in the earth's atmosphere. The data generated in the greenhouse warming simulations (Business-as-Usual scenario of IPCC) with the climate models developed at Max Planck Institute for Meteorology, Hamburg have been used to assess future plausible hydrological scenario for the South Asian region. The model results indicate enhanced surface warming (2.7°C for summer and 3.6°C for winter) over the land reginos of South Asia during the next hundred years. While there is no significant change in the precipitation over most of the land regions during winter, substantial increase in precipitation is likely to occur during summer. As a result, an increase in soil moisture is likely over central India, Bangladesh and South China during summer but a statistically significant decline in soil moisture is expected over central China in winter. A moderate decrease in surface runoff may occur over large areas of central China during winter while the flood prone areas of NE-India, Bangladesh and South China are likely to have an increase in surface runoff during summer by the end of next century.

Lal, M.

1994-06-01

233

Mainz Isoprene Mechanism 2 (MIM2): an isoprene oxidation mechanism for regional and global atmospheric modelling  

NASA Astrophysics Data System (ADS)

We present an oxidation mechanism of intermediate size for isoprene (2-methyl-1,3-butadiene) suitable for simulations in regional and global atmospheric chemistry models, which we call MIM2. It is a reduction of the corresponding detailed mechanism in the Master Chemical Mechanism (MCM v3.1) and intended as the second version of the well-established Mainz Isoprene Mechanism (MIM). Our aim is to improve the representation of tropospheric chemistry in regional and global models under all NOx regimes. We evaluate MIM2 and re-evaluate MIM through comparisons with MCM v3.1. We find that MIM and MIM2 compute similar O3, OH and isoprene mixing ratios. Unlike MIM, MIM2 produces small relative biases for NOx and organic nitrogen-containing species due to a good representation of the alkyl and peroxy acyl nitrates (RONO2 and RC(O)OONO2). Moreover, MIM2 computes only small relative biases with respect to hydrogen peroxide (H2O2), methyl peroxide (CH3OOH), methanol (CH3OH), formaldehyde (HCHO), peroxy acetyl nitrate (PAN), and formic and acetic acids (HCOOH and CH3C(O)OH), being always below ?6% in all NOx scenarios studied. Most of the isoprene oxidation products are represented explicitly, including methyl vinyl ketone (MVK), methacrolein (MACR), hydroxyacetone and methyl glyoxal. MIM2 is mass-conserving with respect to carbon, including CO2 as well. Therefore, it is suitable for studies assessing carbon monoxide (CO) from biogenic sources, as well as for studies focused on the carbon cycle. Compared to MIM, MIM2 considers new species like acetaldehyde (CH3CHO), propene (CH2=CHCH3) and glyoxal (CHOCHO) with global chemical production rates for the year 2005 of 7.3, 9.5 and 33.8 Tg/yr, respectively. Our new mechanism is expected to substantially improve the results of atmospheric chemistry models by representing many more intermediates, that are transported and deposited, which allows us to test model results with many more new measurements. MIM2 allows regional and global models to easily incorporate new experimental results on the chemistry of organic species.

Taraborrelli, D.; Lawrence, M. G.; Butler, T. M.; Sander, R.; Lelieveld, J.

2009-04-01

234

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

NASA Astrophysics Data System (ADS)

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

Breil, Marcus; Panitz, Hans-Jürgen

2013-04-01

235

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

236

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

237

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

NASA Astrophysics Data System (ADS)

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

Strawbridge, K. B.

2012-12-01

238

Systematics of radon daughters ([sup 210]Pb - [sup 210]Po) atmospheric fallout to coastal regions  

SciTech Connect

The radon daughters [sup 210]Pb and [sup 210]Po were analyzed in coastal bulk precipitation from Camargue (Mediterranean, France) and Lewes (mid-Atlantic, Delaware, USA) as part of the ECOMARGE and SEEP programs and over periods of 12 and 15 months in 1988 and 1989 respectively. The [sup 210]Po/[sup 210]Pb activity ratio in the Camargue fallout is on the order of 0.4, and less than 0.2 in Lewes fallout. Such low [sup 210]Po/[sup 210]Pb activity ratio in precipitation at the American east coast, may partially explain similar deficit values observed in the surface sea waters along the New England shelf (Bacon et al., 1988). The annual fluxes of [sup 210]Pb in these two regions (Camargue and Lewes) have seen determined to be 0.4 and 0.6 dpm cm[sup -2] respectively, somewhat lower than previous records. The [sup 210]Pb fallout at Camargue shows strong correlation with the rainfall, while that at Lewes showed no such correlation. Efficiency in convective fallout characteristic of the mistral conditions in the Camargue may be one explanation. A the coast in Lewes there is characteristic mixing of continental (dry, radon rich) and marine (wet, radon poor) air masses, and a greater proportion of dry fallout. The atmospheric deposition data for [sup 210]Pb-[sup 210]Po radon daughters will be compared to that sampled simultaneously in coastal oceanic sediment traps to document the potential coupling between coastal atmospheric fallout and ocean fluxes.

Hussain, N.; Church, T. (Univ. of Delaware, Newark (United States)); Heyraud, M.; Fowler, S. (International Lab. Mar. Radioactivity, Monaco (France)); Heussner, S.; Monaco, A. (Univ. of Perpignan (France)); Biscaye, P.; Anderson, R. (Bothat Geochemical, Palisades, NY (United States))

1990-01-09

239

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

240

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

241

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

242

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

SciTech Connect

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

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

1999-01-01

243

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

PubMed

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

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

2013-05-01

244

Regional modeling of the atmospheric fate and transport of benzene and diesel particles.  

PubMed

The Community Multiscale Air Quality model (CMAQ) was modified to simulate the atmospheric fate and transport of benzene and diesel particles. We simulated the July 11-15, 1995 period over a domain covering the eastern United States with a 12-km horizontal resolution and a finer (4 km) resolution over a part of the northeastern United States that includes Washington, DC and New York City. The meteorological fields were obtained from a simulation conducted earlier with the mesoscale model MM5. Gridded emission files for benzene and diesel particles were developed using the SMOKE modeling system. The results of the model simulations showed that benzene concentrations were commensurate with available measurements. Over the 4-km resolution domain, a comparison between simulated and measured 24-h average concentrations showed a fractional error of 0.46, a fractional bias of 0.14, and a coefficient of determination (r2) of 0.25. A comparison between simulated benzene hourly concentrations in New York City and in the Brigantine Wilderness Area, NJ, showed that urban concentrations were greater than the remote area concentrations by a factor of 2-5. The results of the diesel particle simulations showed spatial and temporal patterns that were similar to those obtained for benzene. However, because of the lesser contribution of on-road mobile sources to diesel particle emissions compared to benzene emissions, diesel particle concentrations showed stronger gradients between urban areas and remote areas. A comparison between diesel particle concentrations in New York City and in the Brigantine Wilderness Area, NJ, showed that the urban concentrations were greater than the remote area concentrations by a factor of 2-10. Assuming that diesel particles consist of 50% "elemental" carbon (EC), the simulated EC concentrations were in close agreement (within 10%) with the measured concentration in the urban area (Washington, DC) but were significantly lower than the measured EC concentrations in the remote area (Brigantine Wilderness Area). This result suggests that other sources beside diesel fuel engines contribute to atmospheric EC concentrations and that EC may not be a good surrogate for diesel particles. A comparison of both benzene and diesel particle simulated concentrations between an urban area (New York City) and a remote area (Brigantine Wilderness Area) shows that, at a spatial resolution of 4 km, the regional background may contribute from 10 to 20% to the peak concentrations. These results suggest that the regional background may not be negligible and should be taken into account in urban air toxics studies. PMID:14655713

Seigneur, Christian; Pun, Betty; Lohman, Kristen; Wu, Shiang-Yuh

2003-11-15

245

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

246

Greenhouse gas emissions derived from regional measurement networks and atmospheric inversions: Results from the MCI and INFLUX experiments  

NASA Astrophysics Data System (ADS)

Atmospheric evaluation of emissions inventories is increasingly envisioned as a critical element of greenhouse gas emissions regulation. Atmospheric inversions utilizing dense regional networks of greenhouse gas measurements, however, are scarce. Discussions of the measurements and methods required to infer fluxes at spatial and temporal resolutions sufficient to meet the needs of policy makers, therefore, remain largely hypothetical. We present results from one past field experiment, the North American Carbon Program (NACP) Midcontinent Intensive (MCI) regional study, and preliminary results from a new experiment, the Indianapolis Flux project (INFLUX), both of which include high density regional greenhouse gas measurement networks. Both studies also include detailed regional inventory assessments of greenhouse gas sources and sinks. The MCI results show large amplitude, spatially coherent synoptic and seasonal patterns in boundary layer CO2 mixing ratios correlated with cropping patterns. Regional atmospheric inversions utilizing these data show corrections that tend towards the inventory estimates regardless of the prior flux estimates utilized in the inversion, and the region appears to have been slightly oversampled by the instrument density deployed. The uncertainty bounds associated with the inverted fluxes, however, remain fairly large despite the high density of atmospheric data, and the true uncertainty is difficult to assess. The INFLUX experiment will utilize a similar number of sensors deployed over a spatial domain two to three orders of magnitude smaller in area than the MCI domain, and will attempt to utilize similar techniques to infer anthropogenic emissions at high spatial resolution. We will present the experimental design for this project including the unique challenges of multi-species inversions and the need to deconvolve biological and fossil fuel fluxes. We anticipate that this experiment will serve as a benchmark regarding the accuracy and precision of urban-scale atmospheric inversions.

Davis, K. J.; Andrews, A. E.; Cambaliza, M.; Denning, A.; Gurney, K. R.; Lauvaux, T.; Miles, N. L.; Ogle, S. M.; Possolo, A.; Richardson, S.; Schuh, A. E.; Shepson, P. B.; Sweeney, C.; Turnbull, J. C.; West, T. O.; Whetstone, J. R.

2010-12-01

247

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

248

Atmospheric aerosol light scattering and surface wetness influence the diurnal pattern of net ecosystem exchange in a semi-arid  

E-print Network

Atmospheric aerosol light scattering and surface wetness influence the diurnal pattern of net) showed an unusual pattern at the Blodgett Forest Ameriflux site, with late afternoon NEE lower than early to this site results in higher aerosol particle concentration, light extinction and light scattering during

Cohen, Ronald C.

249

The solar wind interaction with Mars: Recent progress and future directions The Sun has a powerful influence on planetary atmospheres.  

E-print Network

Editorial The solar wind interaction with Mars: Recent progress and future directions The Sun has a powerful influence on planetary atmospheres. This is especially true for planets lacking a global magnetic field, because the solar wind can interact directly with the upper atmo- sphere. Neutral particles

California at Berkeley, University of

250

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

251

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

252

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

253

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

E-print Network

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

Ramírez, Jorge A.

254

Assessing Predictability of Cotton Yields in the Southeastern United States Based on Regional Atmospheric Circulation and Surface Temperatures  

Microsoft Academic Search

The potential to predict cotton yields up to one month before planting in the southeastern United States is assessed in this research. To do this, regional atmospheric variables that are related to historic summer rainfall and cotton yields were identified. The use of simulations of those variables from a global circulation model (GCM) for estimating cotton yields was evaluated. The

Guillermo A. Baigorria; James W. Hansen; Neil Ward; James W. Jones; James J. O’Brien

2008-01-01

255

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

Microsoft Academic Search

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

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

2007-01-01

256

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

257

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

258

Size distributions and characteristics of atmospheric inorganic particles by regional comparative study in Urban Osaka, Japan  

NASA Astrophysics Data System (ADS)

Size distributions and characteristics of atmospheric inorganic particles at two different monitoring sites were statistically compared in order to survey site-specific original sources of the particulate constituents. The average concentration difference of fine and coarse particles between the sites was, respectively, 1.4 and 4.7 ?g/m 3, and coarse particulate Fe, Mn, Zn and Pb were significantly high at the heavy traffic-flow site. Coarse particulate Zn and Pb form a closely related cluster group but Mn belongs to another independent group together with Fe. Comparative study for the Zn/Pb ratio possibly suggested that the regional differences of Zn and Pb were derived from road dust components and this might be caused essentially by tire wears and previous lead additives, respectively. On the contrary, the differences of coarse particulate Fe and Mn might be commonly and directly affected by industrial sources such as iron-steel factories close to the heavy traffic-flow site.

Funasaka, Kunihiro; Sakai, Mamoru; Shinya, Masanao; Miyazaki, Takeji; Kamiura, Toshikazu; Kaneco, Satoshi; Ohta, Kiyohisa; Fujita, Tadao

259

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

NASA Technical Reports Server (NTRS)

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

Case, Jonathan

2001-01-01

260

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

NASA Technical Reports Server (NTRS)

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

Case, Jonathan

2000-01-01

261

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

262

The influence of low energy hadron interaction models in CORSIKA code on atmospheric ionization due to heavy nuclei  

NASA Astrophysics Data System (ADS)

The largest uncertainties in a numerical simulation of cosmic ray induced atmospheric cascade are due to hadron interaction models. The influence of low energy hadron interaction models in CORSIKA code on longitudinal cascade development is important. It results longitudinal cascade development, respectively energy deposit and atmospheric ionization by secondary particles. In this work are presented simulations with CORSIKA 6.990 code using GHEISHA 2000, FLUKA 2011 and QGSJET II hadron generators. The energy deposit in the atmosphere by various nuclei, namely Helium, Oxygen and Iron is calculated. The ion pair production in the atmosphere and the impact of the different shower components, precisely the electromagnetic, muon and hadron is estimated according the used hadron generators. The yield function Y for total ionization is compared for various cases. The observed differences and applications are discussed.

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

2013-02-01

263

Influence of the interannual variation of CH4 emissions and OH on recent atmospheric CH4  

NASA Astrophysics Data System (ADS)

Atmospheric methane (CH4) has risen dramatically since preindustrial times and the growth rate has slowed since the early 1990s. The global growth rate has been increasing again after the steady state in 1999-2006. In 2007, the global mean CH4 exceeded the highest value of 2003, and the highest growth rate was observed since 1998. The growth rate of CH4 is determined by the balance between surface emission and chemical reaction with OH and its recent trend with apparent interannual variations (IAV) may be related to changes in the balance. The global CH4 budget has been assessed in many studies and the dominant sources have been identified, but there are still large uncertainties in their individual magnitudes and temporal and spatial distributions on regional scale. In this study, we estimate the year-to-year variation of CH4 fluxes based on Bayesian approach using NIES transport model and investigate the contribution of the variation of CH4 flux and OH to recent variability on the growth rate of CH4. The NIES off-line transport model (Maksyutov and Inoue, 2000) is used to simulate 72 tracers representing a combination of 12 months and 6 emission categories for 6 years (2002-2007), with IAV of NCEP winds and OH fields. We use the monthly mean OH fields simulated by CHASER developed for studying atmospheric environment and radiative forcing (Sudo et al., 2002). EDGAR and GISS inventories are used as a prior flux with strengths for individual flux types described in Patra et al. (2009) and the IAV of a prior flux is not included in this study. Observations are taken from GLOBALVIEW-CH4 (2008). In the year-to-year variation of regional CH4 flux anomalies estimated in inversions, we found that the northern regions show smother variations as compared with the tropical and the southern regions. However, there is good agreement in the year-to-year variation on between the northern regional flux anomalies and the global growth rate of CH4. In addition, we found that the variation of wetland emissions is the dominant contribution to the IAV of CH4 emissions. In the northern regions, a little variation of the estimated CH4 fluxes is shown in 2002-2005 and a large variation is shown in 2006-2007: a large positive anomaly is shown in 2007 with a large negative anomaly in 2006. It is shown more clearly in high northern latitudes where 24% of the estimated wetland emissions is emitted. The similar variation is shown in CH4 oxidation by chemical reaction in the northern regions. The column-averaged OH anomaly increases slightly in 2006 and decreases in 2007. It suggests that the decrease of OH and the increase of wetland emission in 2006-2007 can be a contributor to recent increase of CH4 growth rate.

Kim, Heon-Sook; Maksyutov, Shamil; Patra, Prabir K.; Sudo, Kengo; Inoue, Gen

2010-05-01

264

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

Microsoft Academic Search

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

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

2006-01-01

265

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

Microsoft Academic Search

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

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

2006-01-01

266

Influence of ketamine on regional brain glucose use  

SciTech Connect

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

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

1988-08-01

267

Industry Association Influence Upon State Aquaculture Policy in the North Central Region1  

Microsoft Academic Search

States within the North Central Region of the U.S. differ in their approaches to regulating the aquaculture industry. According to interest group theory, these policy differences may be attributable to differences in the abilities of state aquaculture associations to influence state policy makers. The influence abilities of six aquaculture industry associations were examined in relation to the corresponding state policy

SUSAN K. THOMAS; DONALD W. FLOYD; ROBERT L. VKRTREES

268

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

269

Anthropogenic aerosol radiative forcing in Asia derived from regional models with atmospheric and aerosol data assimilation  

NASA Astrophysics Data System (ADS)

An estimate of monthly 3-D aerosol solar heating rates and surface solar fluxes in Asia from 2001 to 2004 is described here. This product stems from an Asian aerosol assimilation project, in which a) the PNNL regional model bounded by the NCEP reanalyses was used to provide meteorology, b) MODIS and AERONET data were integrated for aerosol observations, c) the Iowa aerosol/chemistry model STEM-2K1 used the PNNL meteorology and assimilated aerosol observations, and d) 3-D (X-Y-Z) aerosol simulations from the STEM-2K1 were used in the Scripps Monte-Carlo Aerosol Cloud Radiation (MACR) model to produce total and anthropogenic aerosol direct solar forcing for average cloudy skies. The MACR model and STEM-2K1 both used the PNNL model resolution of 0.45°×0.4° in the horizontal and of 23 layers in the troposphere. The 2001-2004 averaged anthropogenic all-sky aerosol forcing is -1.3 Wm-2 (TOA), +7.3 Wm-2 (atmosphere) and -8.6 Wm-2 (surface) averaged in Asia (60-138° E and Equator-45° N). In the absence of AERONET SSA assimilation, absorbing aerosol concentration (especially BC aerosol) is much smaller, giving -2.3 Wm-2 (TOA), +4.5 Wm-2 (atmosphere) and -6.8 Wm-2 (surface), averaged in Asia. In the vertical, monthly forcing is mainly concentrated below 600 hPa with maximum around 800 hPa. Seasonally, low-level forcing is far larger in dry season than in wet season in South Asia, whereas the wet season forcing exceeds the dry season forcing in East Asia. The anthropogenic forcing in the present study is similar to that in Chung et al. (2005) in overall magnitude but the former offers fine-scale features and simulated vertical profiles. The interannual variability of the computed anthropogenic forcing is significant and extremely large over major emission outflow areas. Given the interannual variability, the present study's estimate is within the implicated range of the 1999 INDOEX result.

Chung, C. E.; Ramanathan, V.; Carmichael, G.; Kulkarni, S.; Tang, Y.; Adhikary, B.; Leung, L. R.; Qian, Y.

2010-07-01

270

Anthropogenic aerosol radiative forcing in Asia derived from regional models with atmospheric and aerosol data assimilation  

NASA Astrophysics Data System (ADS)

A high-resolution estimate of monthly 3-D aerosol solar heating rates and surface solar fluxes in Asia from 2001 to 2004 is described here. This product stems from an Asian aerosol assimilation project, in which a) the PNNL regional model bounded by the NCEP reanalyses was used to provide meteorology, b) MODIS and AERONET data were integrated for aerosol observations, c) the Iowa aerosol/chemistry model STEM-2K1 used the PNNL meteorology and assimilated aerosol observations, and d) 3-D (X-Y-Z) aerosol simulations from the STEM-2K1 were used in the Scripps Monte-Carlo Aerosol Cloud Radiation (MACR) model to produce total and anthropogenic aerosol direct solar forcing for average cloudy skies. The MACR model and STEM both used the PNNL model resolution of 0.45°×0.4° in the horizontal and of 23 layers in the troposphere. The 2001-2004 averaged anthropogenic all-sky aerosol forcing is -1.3 W m-2 (TOA), +7.3 W m-2 (atmosphere) and -8.6 W m-2 (surface) averaged in Asia (60-138° E and Eq. -45° N). In the absence of AERONET SSA assimilation, absorbing aerosol concentration (especially BC aerosol) is much smaller, giving -2.3 W m-2 (TOA), +4.5 W m-2 (atmosphere) and -6.8 W mm-2 (surface), averaged in Asia. In the vertical, monthly forcing is mainly concentrated below 600 hPa with maxima around 800 hPa. Seasonally, low-level forcing is far larger in dry season than in wet season in South Asia, whereas the wet season forcing exceeds the dry season forcing in East Asia. The anthropogenic forcing in the present study is similar to that in Chung et al. (2005) in overall magnitude but the former offers fine-scale features and simulated vertical profiles. The interannual variability of the computed anthropogenic forcing is significant and extremely large over major emission outflow areas. Given the interannual variability, the present study's estimate is within the implicated range of the 1999 INDOEX result. However, NCAR/CCSM3's anthropogenic aerosol forcing is much smaller than the present study's estimate at the surface, and is outside of what the INDOEX findings can support.

Chung, C. E.; Ramanathan, V.; Carmichael, G.; Kulkarni, S.; Tang, Y.; Adhikary, B.; Leung, L. R.; Qian, Y.

2010-01-01

271

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

272

Sensitivity analysis of upwelling radiances in the 3-5 micrometers region as a function of atmospheric conditions. Technical report  

SciTech Connect

Under the direction of the Remote Sensing Branch of the Naval Research Laboratory (NRL), SPARTA, Inc. calculated upwelling ground-to-space radiances and kernel functions for model atmospheres under different viewing and atmospheric conditions. These sensitivity calculations were then used by NRL personnel in a feasibility study which examined the possibility of obtaining information about atmospheric constituents from a remote sensing platform as it looks through the atmosphere at a source of a known blackbody temperature. In the current sensitivity study, upwelling radiances were calculated for selected bandpasses in the 3-5 micrometers region (1920-3330 1/cm). The results indicated that upwelling radiances are governed by the blackbody temperature at the surface. The impacts of the carbon dioxide profile, sensor platform altitude, surface visibility, and solar contributions (day/night variations) are small or insignificant. The impact of the water vapor profile depends on where in the atmosphere the perturbations exist, the surface blackbody temperature, the viewing angle, and the sensor bandpass. Broadband kernel functions generally peak in the 2-4 km altitude region. Upwelling radiance, 3-5 micrometers Radiance, Sensitivity analysis, Impact of water vapor profile.

Longtin, D.R.; Hummel, J.R.

1994-06-17

273

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

NASA Astrophysics Data System (ADS)

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

Ryu, Jung-Hee; Hayhoe, Katharine

2014-10-01

274

Bioclimatic regions influence genetic structure of four Jordanian Stipa species.  

PubMed

Strong environmental gradients can affect the genetic structure of plant populations, but little is known as to whether closely related species respond similarly or idiosyncratically to ecogeographic variation. We analysed the extent to which gradients in temperature and rainfall shape the genetic structure of four Stipa species in four bioclimatic regions in Jordan. Genetic diversity, differentiation and structure of Stipa species were investigated using amplified fragment length polymorphism (AFLP) molecular markers. For each of the four study species, we sampled 120 individuals from ten populations situated in distinct bioclimatic regions and assessed the degree of genetic diversity and genetic differentiation within and among populations. The widespread ruderals Stipa capensis and S. parviflora had higher genetic diversity than the geographically restricted semi-desert species S. arabica and S. lagascae. In three of the four species, genetic diversity strongly decreased with precipitation, while genetic diversity increased with temperature in S. capensis. Most genetic diversity resided among populations in the semi-desert species (?(ST) = 0.572/0.595 in S. arabica/lagascae) but within populations in the ruderal species (?(ST) = 0.355/0.387 S. capensis/parviflora). Principal coordinate analysis (PCoA) and STRUCTURE analysis showed that Stipa populations of all species clustered ecogeographically. A genome scan revealed that divergent selection at particular AFLP loci contributed to genetic differentiation. Irrespective of their different life histories, Stipa species responded similarly to the bioclimatic gradient in Jordan. We conclude that, in addition to predominant random processes, steep climatic gradients might shape the genetic structure of plant populations. PMID:23369254

Hamasha, H R; Schmidt-Lebuhn, A N; Durka, W; Schleuning, M; Hensen, I

2013-09-01

275

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

NASA Astrophysics Data System (ADS)

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

Breil, Marcus; Panitz, Hans-Jürgen

2014-05-01

276

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

277

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

E-print Network

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

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

2005-10-14

278

Atmospheric deposition maps for the Rocky Mountains  

Microsoft Academic Search

Variability in atmospheric deposition across the Rocky Mountains is influenced by elevation, slope, aspect, and precipitation amount and by regional and local sources of air pollution. To improve estimates of deposition in mountainous regions, maps of average annual atmospheric deposition loadings of nitrate, sulfate, and acidity were developed for the Rocky Mountains by using spatial statistics. A parameter-elevation regressions on

Leora Nanus; Donald H. Campbell; George P. Ingersoll; David W. Clow; M. Alisa Mast

2003-01-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

280

Overview of the Atmospheric Brown Cloud East Asian Regional Experiment 2005 and a study of the aerosol direct radiative forcing in east Asia  

Microsoft Academic Search

This article introduces an international regional experiment, East Asian Regional Experiment 2005 (EAREX 2005), carried out in March-April 2005 in the east Asian region, as one of the first phase regional experiments under the UNEP Atmospheric Brown Cloud (ABC) project, and discusses some outstanding features of aerosol characteristics and its direct radiative forcing in the east Asian region, with some

Teruyuki Nakajima; Soon-Chang Yoon; Veerabhadran Ramanathan; Guang-Yu Shi; Toshihiko Takemura; Akiko Higurashi; Tamio Takamura; Kazuma Aoki; Byung-Ju Sohn; Sang-Woo Kim; Haruo Tsuruta; Nobuo Sugimoto; Atsushi Shimizu; Hiroshi Tanimoto; Yousuke Sawa; Neng-Huei Lin; Chung-Te Lee; Daisuke Goto; Nick Schutgens

2007-01-01

281

Overview of the Atmospheric Brown Cloud East Asian Regional Experiment 2005 and a study of the aerosol direct radiative forcing in east Asia  

Microsoft Academic Search

This article introduces an international regional experiment, East Asian Regional Experiment 2005 (EAREX 2005), carried out in March–April 2005 in the east Asian region, as one of the first phase regional experiments under the UNEP Atmospheric Brown Cloud (ABC) project, and discusses some outstanding features of aerosol characteristics and its direct radiative forcing in the east Asian region, with some

Teruyuki Nakajima; Soon-Chang Yoon; Veerabhadran Ramanathan; Guang-Yu Shi; Toshihiko Takemura; Akiko Higurashi; Tamio Takamura; Kazuma Aoki; Byung-Ju Sohn; Sang-Woo Kim; Haruo Tsuruta; Nobuo Sugimoto; Atsushi Shimizu; Hiroshi Tanimoto; Yousuke Sawa; Neng-Huei Lin; Chung-Te Lee; Daisuke Goto; Nick Schutgens

2007-01-01

282

Modeling interactions of aircraft emissions with global and regional atmospheric chemistry and climate  

Microsoft Academic Search

Aircraft engines emit a variety of chemical compounds that affect atmospheric chemistry and climate. In the research presented here, we have addressed three different issues related to aircraft emissions. The first phase of the research has two parts. In the first part, we have analyzed the effects of potential fleets of aircraft on atmospheric ozone concentrations. We have used a

Mayurakshi Dutta

2006-01-01

283

Isotopic studies of ice core nitrate and atmospheric nitrogen oxides in polar regions  

Microsoft Academic Search

Atmospheric nitrogen oxides regulate concentrations of natural and anthropogenic trace gases through interactions with tropospheric oxidants. Understanding past and present changes in atmospheric NOx (NO + NO2) is possible through measurements of nitrate (NO3- or nitric acid, HNO3) in polar ice cores. This dissertation is comprised of four studies which contribute towards understanding the controls on nitrate isotopes preserved in

Julia C. Jarvis

2008-01-01

284

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

NASA Astrophysics Data System (ADS)

The SAMM (Sea Atmosphere Mediterranean Model) has been developed to study the climate evolution of the Mediterranean and European regions for the 21st Century. SAMM is a new concept of AORCM (Atmosphere-Ocean Regional Climate Model), where a global atmosphere model is locally coupled with a regional ocean circulation model. It consists of the global spectral AGCM ARPEGE-Climate model, whose variable resolution is maximum in the Mediterranean region (50 km), which has been coupled to the Mediterranean Sea limited area OGCM OPAMED (10 km). A 140-year numerical experiment starting in 1960 was run with the AORCM. Up to year 2000, forcing was prescribed from observed values, whereas forcing following a SRES-A2 scenario was applied beyond 2000. In order to ensure the model stability, a simple monthly heat flux correction on air-sea exchanges was applied. The present-climate validation proves that the AORCM is comparable to the state-of-the-art European Atmosphere Regional Climate Models (ARCM) at the same resolution. At first order, the climate change impact over Europe simulated by the AORCM is comparable with ARCM simulations. However the AORCM significantly amplifies the climate change signal over large parts of Europe with respect to the corresponding ARCM: the warming is higher in all seasons and in many areas of Europe (up to 25% of the signal), winters are wetter over northern Europe and summers drier over southern and eastern Europe (up to 50% of the signal). These differences are highly significant and the choice between coupled and non-coupled regional models could be an additional source of uncertainty when evaluating the climate change response over Europe. The factors responsible for these differences are discussed. Among them, the response of the Mediterranean SST, better simulated by the high resolution Mediterranean Sea model of the AORCM, seems to be preponderant. Further mechanism studies and model inter-comparisons are however required to legitimate the present results.

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

2008-09-01

285

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

E-print Network

Influence of volcanic eruptions on the climate of the Asian monsoon region K. J. Anchukaitis,1 B. M throughout much of monsoon Asia. Here, we use long and wellvalidated proxy reconstructions of Asian droughts on the climate of the Asian monsoon region, Geophys. Res. Lett., 37, L22703, doi:10.1029/ 2010GL044843. 1

Xin, Qin

286

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

E-print Network

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

Evans, Jason

287

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

E-print Network

NAO influence on net sea ice production and exchanges in the Arctic region Aixue Hu National Center of the net sea ice production and the sea ice exchanges between the Arctic and its adjacent seas are studied) is the major factor controlling the net sea ice production in the Arctic region since a thinning ice cover

Hu, Aixue

288

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

E-print Network

NAO influence on net sea ice production and exchanges in the Arctic region Aixue Hu, Claes Rooth exchanges between the Arctic and its adjacent seas are studied, using a coupled sea ice-ocean general ice production in the Arctic region since a thinning ice cover suppresses the development of thermal

Hu, Aixue

289

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

SciTech Connect

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

Viall, Nicholeen M.; Klimchuk, James A. [NASA Goddard Space Flight Center, Solar Physics Laboratory, Greenbelt, MD 20706 (United States)

2012-07-01

290

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

291

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

292

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

293

Combined oceanic and atmospheric influences on net accumulation on Devon Ice Cap, Nunavut, Canada  

NASA Astrophysics Data System (ADS)

An annual net accumulation history of the high-elevation region of Devon Ice Cap, Nunavut, Canada, was reconstructed for the period 1963-2003 using five shallow firn cores. Annual net accumulation decreased significantly after 1989. To explain variability in the reconstructed annual net accumulation record, monthly and seasonal moisture-source probabilities were calculated for gridcells throughout the Arctic during 1979-2003. Seasonally, moisture-source probabilities reach a maximum in northern Baffin Bay in late summer/early fall and approach zero throughout the Arctic in winter. Late-summer/early-fall moisture-source probabilities were significantly higher around the North Open Water (NOW) Polynya during the 4 year period of highest annual net accumulation during the 1979-2003 period (1984-87), than during the 4 year period with the lowest annual net accumulation (1994-97). This is due to both a significant decrease in the sea-ice fraction and a significant increase in low-elevation atmospheric transport over the NOW area during the high net accumulation period. Anomalously low net accumulation and anomalously high firnification rates during the 1989-2003 period suggest that a change in ice dynamics, rather than a change in surface mass balance, may explain recent ice-cap thickening observed by laser altimetry.

Colgan, William; Sharp, Martin

294

Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine  

NASA Astrophysics Data System (ADS)

Naturally occurring bromine- and iodine-containing compounds substantially reduce regional, and possibly even global, tropospheric ozone levels. As such, these halogen gases reduce the global warming effects of ozone in the troposphere, and its capacity to initiate the chemical removal of hydrocarbons such as methane. The majority of halogen-related surface ozone destruction is attributable to iodine chemistry. So far, organic iodine compounds have been assumed to serve as the main source of oceanic iodine emissions. However, known organic sources of atmospheric iodine cannot account for gas-phase iodine oxide concentrations in the lower troposphere over the tropical oceans. Here, we quantify gaseous emissions of inorganic iodine following the reaction of iodide with ozone in a series of laboratory experiments. We show that the reaction of iodide with ozone leads to the formation of both molecular iodine and hypoiodous acid. Using a kinetic box model of the sea surface layer and a one-dimensional model of the marine boundary layer, we show that the reaction of ozone with iodide on the sea surface could account for around 75% of observed iodine oxide levels over the tropical Atlantic Ocean. According to the sea surface model, hypoiodous acid--not previously considered as an oceanic source of iodine--is emitted at a rate ten-fold higher than that of molecular iodine under ambient conditions.

Carpenter, Lucy J.; MacDonald, Samantha M.; Shaw, Marvin D.; Kumar, Ravi; Saunders, Russell W.; Parthipan, Rajendran; Wilson, Julie; Plane, John M. C.

2013-02-01

295

Analysis of the atmospheric and emissivity influence on the splitwindow equation for sea surface temperature  

Microsoft Academic Search

In this paper we have analysed the effects of the different atmospheric species (water vapour, fixed gases and aerosols) and the surface emissivity on the split-window method for determining the sea surface temperature. The widely used split-window method is based on the differential absorption of water vapour in the atmospheric window 10.5ndash;12.5 ?m. Other atmospheric species with absorption coefficients different

C. Coll; V. Caselles

1994-01-01

296

Regional and historical variation in the nitrogen content of Racomitrium lanuginosum in Britain in relation to atmospheric nitrogen deposition.  

PubMed

The moss Racomitrium lanuginosum (Hedw.) Brid. is an important component of the drier parts of ombrotrophic mires and montane heaths in north-western Britain. The extent and quality of the montane heaths dominated by R. lanuginosum has declined in recent decades, perhaps in part due to the effects of acidic deposition at high elevations. This paper examines the effect of atmospheric nitrogen deposition, which has increased during this century, on the nitrogen content of R. lanuginosum in Britain. The nitrogen content of the moss reflects the magnitude of the atmospheric supply being least in north-western Scotland and greatest (as much as six-fold greater) near to urban centres in northern England. This regional difference was less marked (only approx. two-fold) during the 19th century (as revealed from the analysis of herbarium specimens) when nitrogen concentrations were appreciably lower. Transplant studies both between regions and between sites within a mountain system demonstrated the importance of atmospheric deposition in determining the tissue nitrogen concentration of the moss. The results are discussed in relation to the potential importance of the enhanced atmospheric nitrogen supply to the normally nitrogen-impoverished montane heaths, and to the growth and persistence of the moss. PMID:15091715

Baddeley, J A; Thompson, D B; Lee, J A

1994-01-01

297

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

NASA Astrophysics Data System (ADS)

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

Goly, Aneesh; Teegavarapu, Ramesh S. V.

2014-06-01

298

The effect of regional ocean-atmosphere coupling on the long-term variability in the Pacific Ocean  

Microsoft Academic Search

A fully coupled ocean-atmosphere model is applied to highlight the mechanism of the long-term variability (including decadal\\u000a and longer time scales) in the Pacific Ocean. We are interested in the effect of oceanatmosphere coupling of different regions\\u000a during these processes. The control run successfully simulates the Pacific long-term variability, whose leading modes are\\u000a the Pacific (inter) Decadal Oscillation (PDO) and

Lin Feng; Dexing Wu; Xiaopei Lin; Xiangfeng Meng

2010-01-01

299

Influence of departures from LTE on oxygen and calcium abundance determination in the atmospheres of A-K stars.  

NASA Astrophysics Data System (ADS)

Comprehensive model atoms for O I and Ca I -Ca II were applied to evaluate the influence of the departures from LTE upon O and Ca abundance determinations for a wide range of spectral types. It was found that non-LTE line formation led to large negative abundance corrections for the infrared O I ? 7771-5 Å triplet lines, while the non-LTE correction does not exceed 0.05 dex in absolute value for O I lines in the visible region for main-sequence stars. For Ca II, the sign and magnitude of the NLTE correction depends on the line in question and on the stellar parameters. As a test of the non-LTE method, O and Ca abundances were derived for a few A-type stars with well determined parameters. It was found that non-LTE largely removes the differences in abundances between the infrared O I ? 7771-5 Å and visible O I lines which are obtained when LTE is assumed. For example, for Vega, the difference of 1.23 dex in LTE is reduced to 0.14 dex in non-LTE. For each star investigated, the calcium abundances determined in non-LTE from lines of the two ionization stages (Ca I and Ca II) were consistent within the error bars, in contrast to the LTE case, where (Ca I - Ca II) can range from -0.13 to +0.14 for different stars. Non-LTE abundance corrections for oxygen and calcium lines have been calculated for a grid of model atmospheres encompassing a wide range of stellar parameters.

Sitnova, T.; Mashonkina, L.; Ryabchikova, T.; Pakhomov, Yu.

2014-11-01

300

Influence of Atmospheric Modes of Variability on Mediterranean Sea Surface Heat Exchange from a 12km Dynamically Downscaled Reanalysis  

NASA Astrophysics Data System (ADS)

Earlier research on the impacts of the first four modes of atmospheric variability in the North Atlantic / Europe region on air-sea heat exchange in the Mediterranean Sea will be extended to higher spatial resolution using the ALADIN 12 km dynamical downscaling of the ERA-Interim reanalysis. Observation based indices of the modes from the NOAA Climate Prediction Centre (CPC) are used together with the 12 km ALADIN surface flux fields for the period 1979-2012 to determine the sensitivity of the mean heat budget of the full Mediterranean basin and the eastern and western sub-basins to surface forcing at higher resolutions than previously considered. The four modes are the North Atlantic Oscillation (NAO), East Atlantic pattern (EA), Scandinavian pattern (SCAN) and East Atlantic / West Russian pattern (EA/WR). Results at coarser resolution using the NCEP/NCAR and 50 km resolution ARPERA reanalysis will also be reviewed. These indicate that winter anomalies dominate the annual mean heat budget and the leading mode, the NAO, has a surprisingly small impact on the full basin winter mean heat budget, < 5 Wm-2. In contrast, the EA mode has a major effect, of order 25 Wm-2, with similar impacts on both the eastern and western Mediterranean. The SCAN mode has the weakest influence of those considered. The EA/WR mode plays a significant role but, in contrast to the EA mode, it generates a dipole in the heat exchange with an approximately equal and opposite signal of about 15 Wm-2 on the eastern and western sub-basins. New results will be presented which reveal the extent to which these earlier conclusions still hold at the higher 12km resolution now possible using ALADIN.

Josey, Simon; Somot, Samuel

2014-05-01

301

The influence of atmospheric circulation on the mid-Holocene climate of Europe: a data-model comparison  

NASA Astrophysics Data System (ADS)

The atmospheric circulation is a key area of uncertainty in climate model simulations of future climate change, especially in mid-latitude regions such as Europe where atmospheric dynamics have a significant role in climate variability. It has been proposed that the mid-Holocene was characterized in Europe by a stronger westerly circulation in winter comparable with a more positive AO/NAO, and a weaker westerly circulation in summer caused by anti-cyclonic blocking near Scandinavia. Model simulations indicate at best only a weakly positive AO/NAO, whilst changes in summer atmospheric circulation have not been widely investigated. Here we use a new pollen-based reconstruction of European mid-Holocene climate to investigate the role of atmospheric circulation in explaining the spatial pattern of seasonal temperature and precipitation anomalies. We find that the footprint of the anomalies is entirely consistent with those from modern analogue atmospheric circulation patterns associated with a strong westerly circulation in winter (positive AO/NAO) and a weak westerly circulation in summer associated with anti-cyclonic blocking (positive SCAND). We find little agreement between the reconstructed anomalies and those from 14 GCMs that performed mid-Holocene experiments as part of the PMIP3/CMIP5 project, which show a much greater sensitivity to top-of-the-atmosphere changes in solar insolation. Our findings are consistent with data-model comparisons on contemporary timescales that indicate that models underestimate the role of atmospheric circulation in recent climate change, whilst also highlighting the importance of atmospheric dynamics in explaining interglacial warming.

Mauri, A.; Davis, B. A. S.; Collins, P. M.; Kaplan, J. O.

2014-10-01

302

Assessment of ground-based atmospheric observations for verification of greenhouse gas emissions from an urban region  

PubMed Central

International agreements to limit greenhouse gas emissions require verification to ensure that they are effective and fair. Verification based on direct observation of atmospheric greenhouse gas concentrations will be necessary to demonstrate that estimated emission reductions have been actualized in the atmosphere. Here we assess the capability of ground-based observations and a high-resolution (1.3 km) mesoscale atmospheric transport model to determine a change in greenhouse gas emissions over time from a metropolitan region. We test the method with observations from a network of CO2 surface monitors in Salt Lake City. Many features of the CO2 data were simulated with excellent fidelity, although data-model mismatches occurred on hourly timescales due to inadequate simulation of shallow circulations and the precise timing of boundary-layer stratification and destratification. Using two optimization procedures, monthly regional fluxes were constrained to sufficient precision to detect an increase or decrease in emissions of approximately 15% at the 95% confidence level. We argue that integrated column measurements of the urban dome of CO2 from the ground and/or space are less sensitive than surface point measurements to the redistribution of emitted CO2 by small-scale processes and thus may allow for more precise trend detection of emissions from urban regions. PMID:22611187

McKain, Kathryn; Wofsy, Steven C.; Nehrkorn, Thomas; Eluszkiewicz, Janusz; Ehleringer, James R.; Stephens, Britton B.

2012-01-01

303

Assessment of ground-based atmospheric observations for verification of greenhouse gas emissions from an urban region.  

PubMed

International agreements to limit greenhouse gas emissions require verification to ensure that they are effective and fair. Verification based on direct observation of atmospheric greenhouse gas concentrations will be necessary to demonstrate that estimated emission reductions have been actualized in the atmosphere. Here we assess the capability of ground-based observations and a high-resolution (1.3 km) mesoscale atmospheric transport model to determine a change in greenhouse gas emissions over time from a metropolitan region. We test the method with observations from a network of CO(2) surface monitors in Salt Lake City. Many features of the CO(2) data were simulated with excellent fidelity, although data-model mismatches occurred on hourly timescales due to inadequate simulation of shallow circulations and the precise timing of boundary-layer stratification and destratification. Using two optimization procedures, monthly regional fluxes were constrained to sufficient precision to detect an increase or decrease in emissions of approximately 15% at the 95% confidence level. We argue that integrated column measurements of the urban dome of CO(2) from the ground and/or space are less sensitive than surface point measurements to the redistribution of emitted CO(2) by small-scale processes and thus may allow for more precise trend detection of emissions from urban regions. PMID:22611187

McKain, Kathryn; Wofsy, Steven C; Nehrkorn, Thomas; Eluszkiewicz, Janusz; Ehleringer, James R; Stephens, Britton B

2012-05-29

304

Influence of the doping and annealing atmosphere on zinc oxide thin films deposited by spray pyrolysis  

Microsoft Academic Search

Undoped and doped (indium and aluminium) zinc oxide (ZnO) thin films have been prepared by spray pyrolysis, and the effect of the doping and annealing atmosphere on the electrical, optical and structural properties of the produced films has been investigated. The deposited films have a high resistivity. Annealing the films in an argon atmosphere or under vacuum leads to a

P Nunes; A Malik; B Fernandes; E Fortunato; P Vilarinho; R Martins

1999-01-01

305

The influence of the Earths magnetic field on upper atmospheric composition  

Microsoft Academic Search

Ionisation due to extraterrestrial charged particle precipitation leads to the formation of NOx and HOx in the stratosphere and mesosphere. Both NOx and HOx formation will alter the composition of the upper atmosphere significantly, as both are involved in katalytic ozone depletion cycles. While HOx, however, is extremely short-lived in the upper stratosphere and consequently, will affect the atmospheric composition

M. von Koenig; J. Burrows; M. P. Chipperfield; C. Jackman; M. Kallenrode; K. F. Kuenzi; M. Quack

2001-01-01

306

A near-field tool for simulating the upstream influence of atmospheric observations: The Stochastic Time-Inverted Lagrangian Transport (STILT) model  

NASA Astrophysics Data System (ADS)

We introduce a tool to determine surface fluxes from atmospheric concentration data in the midst of distributed sources or sinks over land, the Stochastic Time-Inverted Lagrangian Transport (STILT) model, and illustrate the use of the tool with CO2 data over North America. Anthropogenic and biogenic emissions of trace gases at the surface cause large variations of atmospheric concentrations in the planetary boundary layer (PBL) from the "near field," where upstream sources and sinks have strong influence on observations. Transport in the near field often takes place on scales not resolved by typical grid sizes in transport models. STILT provides the capability to represent near-field influences, transforming this noise to signal useful in diagnosing surface emissions. The model simulates transport by following the time evolution of a particle ensemble, interpolating meteorological fields to the subgrid scale location of each particle. Turbulent motions are represented by a Markov chain process. Significant computational savings are realized because the influence of upstream emissions at different times is modeled using a single particle simulation backward in time, starting at the receptor and sampling only the portion of the domain that influences the observations. We assess in detail the physical and numerical requirements of STILT and other particle models necessary to avoid inconsistencies and to preserve time symmetry (reversibility). We show that source regions derived from backward and forward time simulations in STILT are similar, and we show that deviations may be attributed to violation of mass conservation in currently available analyzed meterological fields. Using concepts from information theory, we show that the particle approach can provide significant gains in information compared to conventional gridcell models, principally during the first hours of transport backward in time, when PBL observations are strongly affected by surface sources and sinks.

Lin, J. C.; Gerbig, C.; Wofsy, S. C.; Andrews, A. E.; Daube, B. C.; Davis, K. J.; Grainger, C. A.

2003-08-01

307

Trace element pollution records in some UK lake sediments, their history, influence factors and regional differences.  

PubMed

Sediment cores were taken from six sites across the UK. Apart from Banbury Reservoir in London, all the other sites are relatively remote lakes. Trace elements Pb, Zn, Cu, Cd, Cr, Ni, Sn, As and V, major elements such as Fe, Mn, Ti and Al were analysed, and organic content measured as loss-on-ignition was determined in all of these cores. The result shows that these relatively remote sites have experienced enhanced atmospheric deposition of anthropogenically derived trace elements for over 100 years, and the contamination might start before industrialisation. Trace metal contamination remains the highest level at Banbury Reservoir showing "pollution source" influence. Despite the considerable reduction in atmospheric deposition in recent years, although some of the element concentrations in the surface sediments have declined, they are still much higher than their natural background values. In these sites, trace element pollution records have been influenced by many different factors. Redox condition could affect As distribution in the sediments. Sediment matrix could also affect trace element pollution signal. Apart from direct atmospheric deposition, the distributions of trace elements in the sediments have been affected by forestry activities and catchment erosion, and more contaminated soil in-wash could increase sediment pollution whilst less contaminated soil could dilute sediment pollution. In some sites, data suggest that catchment in-wash is an important source of elements for the lakes. PMID:15607780

Yang, Handong; Rose, Neil

2005-01-01

308

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

SciTech Connect

In this project we developed further a twin approach to the study of regional-scale climate variability and change. The two approaches involved probabilistic network (PN) models (sometimes called dynamic Bayesian networks) and intermediate-complexity coupled ocean-atmosphere models (ICMs). We thus made progress in identifying the predictable modes of climate variability and investigating their impacts on the regional scale. In previous work sponsored by DOE�s Climate Change Prediction Program (CCPP), we had developed a family of PNs (similar to Hidden Markov Models) to simulate historical records of daily rainfall, and used them to downscale seasonal predictions of general circulation models (GCMs). Using an idealized atmospheric model, we had established a novel mechanism through which ocean-induced sea-surface temperature (SST) anomalies might in�uence large-scale atmospheric circulation patterns on interannual and longer time scales; similar patterns were found in a hybrid coupled ocean�atmosphere�sea-ice model. In this continuation project, we built on these ICM results and PN model development to address prediction of rainfall and temperature statistics at the local scale, associated with global climate variability and change, and to investigate the impact of the latter on coupled ocean�atmosphere modes. Our main project results consist of extensive further development of the hidden Markov models for rainfall simulation and downscaling together with the development of associated software; new intermediate coupled models; a new methodology of inverse modeling for linking ICMs with observations and GCM simulations, called empirical mode reduction (EMR); and observational studies of decadal and multi-decadal natural climate variability, informed by ICM simulations. A particularly timely by-product of this work is an extensive study of clustering of cyclone tracks in the extratropical Atlantic and the western Tropical Pacific, with potential applications to predicting landfall.

M. Ghil (UCLA), PI; S. Kravtsov (UWM); A. W. Robertson (IRI); P. Smyth (UCI)

2008-10-14

309

Regional Climate Downscaling Of African Climate Using A High-Resolution Global Atmospheric Model: Validation And Future Projection  

NASA Astrophysics Data System (ADS)

Climate change impact assessment and adaptation planning require region specific information with high spatial resolution, since the climate and weather effects are directly felt at the local scale. While most of the state-of-the-art General Circulation Models lack adequate spatial resolution, regional climate models (RCM) used in a nested domain are generally incapable of incorporating the two-way exchanges between regional and global climate. In this study we use a very high resolution atmospheric general circulation model HiRAM, developed at NOAA GFDL, to investigate the regional climate changes over CORDEX African domain. The HiRAM simulations are performed with a horizontal grid spacing of 25 km, which is an ample resolution for regional climate simulation. HiRAM has the advantage of naturally describing interaction between regional and global climate. Historic (1975-2004) simulations and future (2007-2050) projections, with both RCP 4.5 and RCP 8.5 pathways, are conducted in line with the CORDEX protocol. A coarse resolution sea surface temperature (SST) is prescribed from the GFDL Earth System Model runs of IPPC AR5, as bottom boundary condition over ocean. The GFDL Land Surface Model (LM3) is employed to calculate physical processes at surface and in soil. The preliminary analysis of the performance of HiRAM, using historic runs, shows it reproduces the regional climate adequately well in comparison with observations. Significant improvement in the simulation of regional climate is evident in comparison with the coarse resolution driving model. Future projections predict an increase in atmospheric temperature over Africa with stronger warming in the subtropics than in tropics. A significant strengthening of West African Monsoon and a southward shift of the summer rainfall maxima over Africa is predicted in both RCP 4.5 and RCP8.5 scenarios.

Raj, J.; Stenchikov, G. L.; Bangalath, H.

2013-12-01

310

Quantitative Analysis of Magnetosphere-Ionosphere-Atmosphere Coupling Processes in the Region of Electron Diffuse Aurora  

NASA Astrophysics Data System (ADS)

Diffuse auroral precipitation covers a broad range of geomagnetic latitudes, which map along field lines from the inner magnetosphere to the plasma sheet. This precipitation of energetic electrons is a consequence of pitch-angle scattering due to interactions with assorted types of plasma waves. The diffuse aurora is a critically important source of ionizing energy input to the middle atmosphere and heating of the thermal plasma. The dissipation processes of magnetospheric electrons in the upper atmosphere is also affiliated with cascading of higher energy electrons toward thermal energies and the production of secondary electrons. These lower energy electrons can escape back to the magnetosphere, encounter pitch angle scattering processes, and become trapped on closed magnetic field lines. In this talk we provide a quantitative analysis of magnetosphere-ionosphere-atmosphere coupling processes in the electron diffuse aurora, focusing on the energy and particle interplay between the two magnetically conjugate ionospheres in the presence of electrostatic electron cyclotron harmonic waves observed by THEMIS.

Khazanov, George V.; Glocer, Alex

2014-05-01

311

Atmospheric numerical simulation of the aerosol microphysics and radiative effects in a regional biomass burning smoke plume in South America  

NASA Astrophysics Data System (ADS)

A study about the atmospheric transport of biomass burning emissions in the Amazon and the central of Brazil including its radiative effects is presented. The sources are spatially and temporally distributed and daily assimilated, according to the biomass burning spots defined by GOES-8 ABBA fire products. A fire smoke particles source parameterization, including aerosol particle concentration and optical properties, was used to build the initial smoke plumes associated with biomass burning in tropical forest and savanna. This study is carried out through a numerical simulation of the atmospheric motions using the atmospheric model RAMS "Regional Atmospheric Modeling System" and the coupled microphysics aerosol model CARMA "Community Aerosol &Radiation Model for Atmospheres". In this method the mass conservation equation and aerosol particle process, like nucleation, coagulation, condensation and dry deposition, are resolved for the biomass burning aerosol particles. The advection, in a resolved scale, and turbulent transport, in a sub-grid scale, are resolved using RAMS model parameterizations. A transport sub-grid parameterization, associated to deep and shallow cumulus convection, not explicitly resolved by the model due its low spatial resolution, is introduced. Also, a wet deposition term, coupled to the cumulus parameterization, is taken into account. The methodology is applied to a case study on August 2002 and the responses of the model to the presence of the aerosol particles in the atmosphere are explored. Also the comparison of the simulated smoke haze layer with MODIS products pointed out the usefulness of the sources emissions parameterization and the suitability of the aerosol process description presented here.

Longo, K.; Freitas, S.; Silva Dias, M.; Silva Dias, P.; Chatfield, R.

2003-04-01

312

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

USGS Publications Warehouse

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

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

2005-01-01

313

Influence of the freeboard region in a fluidized-bed catalytic-cracking regenerator  

Microsoft Academic Search

The influence of the freeboard region in a fluidized-bed catalytic-cracking regenerator was analyzed by using a continuous stirred tank reactor model to describe the dense phase region and George and Grace's model for entrainment to account for the effect of recirculation of particles through the cyclones. Tests on an industrial-scale catalytic-cracking regenerator showed that the effect of the freeboard on

Hugo I. De Lasa; John R. Grace

1979-01-01

314

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

Microsoft Academic Search

The atmospheric concentration, wet deposition, and inferred dry deposition of selected air pollutants reported over two 5-year periods in the 1990s at or near 34 rural Clean Air Status and Trends Network (CASTNET) sites located in the eastern United States (U.S.) are adjusted for known biases, composed into seasonal values, and examined. Several terms are defined for the current study,

Joseph E. Sickles II; Douglas S. Shadwick

2007-01-01

315

PROBING THE TERMINATOR REGION ATMOSPHERE OF THE HOT-JUPITER XO-1b WITH TRANSMISSION SPECTROSCOPY  

SciTech Connect

We report here the first infrared spectrum of the hot-Jupiter XO-1b. The observations were obtained with the NICMOS instrument on board the Hubble Space Telescope during a primary eclipse of the XO-1 system. Near photon-noise-limited spectroscopy between 1.2 and 1.8 {mu}m allows us to determine the main composition of this hot-Jupiter's planetary atmosphere with good precision. This is the third hot-Jupiter's atmosphere for which spectroscopic data are available in the near-IR. The spectrum shows the presence of water vapor (H{sub 2}O), methane (CH{sub 4}), and carbon dioxide (CO{sub 2}), and suggests the possible presence of carbon monoxide (CO). We show that the published IRAC secondary transit emission photometric data are compatible with the atmospheric composition at the terminator determined from the NICMOS spectrum, with a range of possible mixing ratios and thermal profiles; additional emission spectroscopy data are needed to reduce the degeneracy of the possible solutions. Finally, we note the similarity between the 1.2-1.8 {mu}m transmission spectra of XO-1b and HD 209458b, suggesting that in addition to having similar stellar/orbital and planetary parameters the two systems may also have a similar exoplanetary atmospheric composition.

Tinetti, G. [University College London, Department of Physics and Astronomy, Gower Street, London WC1E 6BT (United Kingdom); Deroo, P.; Swain, M. R.; Vasisht, G.; Brown, L. R. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Griffith, C. A. [University of Arizona, Lunar and Planetary Laboratory, 1629 E. University Boulevard, Tucson, AZ 85721 (United States); Burke, C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-65, Cambridge, MA 02138 (United States); McCullough, P. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: g.tinetti@ucl.ac.uk

2010-04-01

316

Interdisciplinary study of atmospheric processes and constituents of the mid-Atlantic coastal region  

NASA Technical Reports Server (NTRS)

Progress is reported in the following areas: analysis of the air quality of Plymouth Park, Chesapeake, Virginia; background analysis and impact assessment for the proposed expansion of Busch Gardens; application of remote sensing and atmospheric interaction; and biosphere interaction. Plans for further study are included.

Kindle, E. C.

1976-01-01

317

Aerosol radiative characteristics at Gosan, Korea, during the Atmospheric Brown Cloud East Asian Regional Experiment 2005  

Microsoft Academic Search

The ABC (Atmospheric Brown Cloud project) Gosan campaign 2005 (EAREX2005) was carried out at Gosan on Cheju Island, Korea, in March 2005. The objective of the campaign was to clarify aerosol characteristics as well as to compare each instrument for radiation and chemical observation. From these observations, eleven clear sky cases were selected and analyzed to estimate the aerosol radiative

Tamio Takamura; Nobuo Sugimoto; Atsushi Shimizu; Akihiro Uchiyama; Akihiro Yamazaki; Kazuma Aoki; Teruyuki Nakajima; B. J. Sohn; Hideaki Takenaka

2007-01-01

318

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

E-print Network

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 ...

Santer, Benjamin D.

319

The influence of the Earths magnetic field on upper atmospheric composition  

NASA Astrophysics Data System (ADS)

Ionisation due to extraterrestrial charged particle precipitation leads to the formation of NOx and HOx in the stratosphere and mesosphere. Both NOx and HOx formation will alter the composition of the upper atmosphere significantly, as both are involved in katalytic ozone depletion cycles. While HOx, however, is extremely short-lived in the upper stratosphere and consequently, will affect the atmospheric composition only during particle precipitation events, NOx is believed to exist for months after big particle events, and thus could be transported down into the lower stratosphere during polar winter. Where and how far extraterrestrial charged particles can penetrate into the atmosphere however is determined by the strengths and form of the Earth magnetic field. We use a 2 D chemistry, transport and radiation model to investigate how different possible scenarios of the Earth magnetic field will affect the upper atmosphere NOx and HOx budget, and consequently, stratospheric and mesospheric ozone.

von Koenig, M.; Burrows, J.; Chipperfield, M. P.; Jackman, C.; Kallenrode, M.; Kuenzi, K. F.; Quack, M.

2001-12-01

320

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

E-print Network

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

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

2010-04-01

321

Influence of Modified Atmosphere Storage on Aflatoxin Production in High Moisture Corn  

PubMed Central

Samples of freshly harvested corn and remoistened corn were inoculated with Aspergillus flavus and stored for 4 weeks at about 27 C in air and three modified atmospheres. Aflatoxins and fat acidity were determined weekly. Corn stored in the modified atmospheres did not accumulate over 15 ?g of aflatoxin B1 per kg and 20 ?g of total aflatoxins per kg. Corn from the high CO2 treatment (61.7% CO2, 8.7% O2, and 29.6% N2) was visibly molded at 4 weeks and had a higher fat acidity than the other treatments. In the N2 (99.7% N2 and 0.3% O2) and controlled atmosphere (13.5% CO2, 0.5% O2, 84.8% N2) treatments, a fermentation-like odor was detected. When the corn was removed from the modified atmospheres it deteriorated rapidly and was soon contaminated with aflatoxins. PMID:803817

Wilson, David M.; Jay, Edward

1975-01-01

322

The potential for regional-scale bias in top-down CO2 flux estimates due to atmospheric transport errors  

NASA Astrophysics Data System (ADS)

Estimates of CO2 fluxes that are based on atmospheric data rely upon a meteorological model to simulate atmospheric CO2 transport. These models provide a quantitative link between surface fluxes of CO2 and atmospheric measurements taken downwind. Therefore, any errors in the meteorological model can propagate into atmospheric CO2 transport and ultimately bias the estimated CO2 fluxes. These errors, however, have traditionally been difficult to characterize. To examine the effects of CO2 transport errors on estimated CO2 fluxes, we use a global meteorological model-data assimilation system known as "CAM-LETKF" to quantify two aspects of the transport errors: error variances (standard deviations) and temporal error correlations. Furthermore, we develop two case studies. In the first case study, we examine the extent to which CO2 transport uncertainties can bias CO2 flux estimates. In particular, we use a common flux estimate known as CarbonTracker to discover the minimum hypothetical bias that can be detected above the CO2 transport uncertainties. In the second case study, we then investigate which meteorological conditions may contribute to month-long biases in modeled atmospheric transport. We estimate 6 hourly CO2 transport uncertainties in the model surface layer that range from 0.15 to 9.6 ppm (standard deviation), depending on location, and we estimate an average error decorrelation time of ∼2.3 days at existing CO2 observation sites. As a consequence of these uncertainties, we find that CarbonTracker CO2 fluxes would need to be biased by at least 29%, on average, before that bias were detectable at existing non-marine atmospheric CO2 observation sites. Furthermore, we find that persistent, bias-type errors in atmospheric transport are associated with consistent low net radiation, low energy boundary layer conditions. The meteorological model is not necessarily more uncertain in these conditions. Rather, the extent to which meteorological uncertainties manifest as persistent atmospheric transport biases appears to depend, at least in part, on the energy and stability of the boundary layer. Existing CO2 flux studies may be more likely to estimate inaccurate regional fluxes under those conditions.

Miller, S. M.; Fung, I.; Liu, J.; Hayek, M. N.; Andrews, A. E.

2014-09-01

323

Regional scale monitoring of atmospheric water vapor content with GNSS infrastructure and numerical model predictions  

NASA Astrophysics Data System (ADS)

Water, which is present in the troposphere in all three phases, has a unique feature among atmospheric components. Besides the formation of clouds and precipitation, it has a key role in atmospheric energy transport and it is the most important greenhouse gas. Due to its temporal and spatial variability, the monitoring of water in the atmosphere requires observations with high temporal and spatial resolution. The water content in the air can be measured directly by radiosondes, in order to monitor the vertical structure of the lower 30-35 km. In addition, remote sensing devices installed on spacecrafts, airframes and the Earth's surface are also available for the measurement of water content. These sensors yield the total water amount of a column of air, the so-called precipitable water (PW) content, in units of kg m-2 or mm. Global Navigation Satellite Systems (GNSS) are capable to monitor various parameters of the atmosphere. With the establishment of the active GNSS network in Hungary, it became feasible to quantify and monitor PW from GNSS observations. The advantage of this solution is the high spatial and temporal resolution of the observations. Modeling of the weather system is performed by the numerical solution of the atmospheric hydro-thermodynamic set of equations. Based on the actual weather as initial condition, the parameters of the expected weather can be estimated. In this study two different meteorological models (WRF and DBCRAS) - run at the Department of Meteorology at Eotvos Lorand University for weather research and forecasting purposes - are compared with the PW estimates provided by the GNSS infrastructure for 7 months in 2011. Deviation between measured data from different sources is near 1 mm in most cases. Forecast PW values show larger deviation from measured data, which results from weather condition dependent forecast errors.

Rozsa, Szabolcs; Zeno Gyongyosi, Andras; Bartholy, Judit; Kern, Aniko; Weidinger, Tamas; Decsi, Anna; Kenyeres, Ambrus; Dombai, Ferenc; Adam, Jozsef

2013-04-01

324

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

Microsoft Academic Search

The Whole Atmosphere Community Climate Model (WACCM3) has been used to study the long-term (more than a few months) effects of solar proton events (SPEs). Extremely large solar proton events occurred in 1972, 1989, 2000, 2001, and 2003 and caused some longer-lasting atmospheric changes. The highly energetic solar protons produced odd hydrogen (HOx) and odd nitrogen (NOy), which then led

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

2009-01-01

325

Upwind convective influences on the isotopic composition of atmospheric water vapor  

E-print Network

, 4 Geography and Regional Planning/Environmental Science, Westfield State University, Westfield continental low-pressure zone forms over the Chaco region of eastern Brazil, feeding convective precipitation

326

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

ERIC Educational Resources Information Center

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

Hamilton, Mary

2014-01-01

327

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

EPA Science Inventory

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

328

NAO influence on net sea ice production and exchanges in the Arctic region: a numerical study  

E-print Network

NAO influence on net sea ice production and exchanges in the Arctic region: a numerical study Aixue The variability of net sea ice production and sea ice exchange between the Arctic and its adjacent seas are studied, using a coupled sea ice-ocean general circulation model. The wind driven divergence (or ice flux

Hu, Aixue

329

Remote influences on freshwater flux variability in the Atlantic warm pool region  

E-print Network

Remote influences on freshwater flux variability in the Atlantic warm pool region Liping Zhang1 October 2012. [1] The understanding of freshwater flux variability is both scientifically and socially important. Local freshwater flux response to a large Atlantic warm pool (AWP) is excessive freshwater

Wang, Chunzai

330

Influence of gas motion on star formation in the central region of a disk galaxy  

Microsoft Academic Search

Explosions in the galactic nuclei are associated with expulsion of huge amount of high velocity gas clouds. The authors investigate the influence of explosive motion on star formation in the inner region of disk galaxies. A strong shock wave generates as a result of the explosion and propagates forward carrying most of the expelled gas behind it. This gas loses

B. Basu; Anuradha Saha; Tara Bhattacharyya

1988-01-01

331

Assessing the influence of regional Environmental Protection Agency offices on state hazardous waste enforcement decisions  

Microsoft Academic Search

In assessing the influence of regional Environmental Protection Agency EPA offices on the state management of hazardous waste programs, we focused on the extent to which federal administrative decisions affect levels of enforcement activity by state environmental agencies and whether these effects vary over time. Our results indicated that state enforcement actions were affected by state program capacity variables such

Kurt D. Cline; Charles Davis

2007-01-01

332

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

E-print Network

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

Handy, Susan L.

333

LAND TENURE AS AN INFLUENCE FACTOR ON NATIONAL\\/REGIONAL FOREST PROGRAMMES IN SPAIN (First draft)  

Microsoft Academic Search

Land tenure is the second most important external influence factor on National\\/Regional Forest Programmes (N\\/RFPs) in Spain after decentralisation. The ownership of forestlands in Mediterranean Europe is mostly private, and the private forests are in general distinguished by the smallholding and a rather indefined legal status. This fact is an impeding factor on forest policy because it has been only

Cristina Montiel Molina

334

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

E-print Network

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

Small, Eric

335

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

Microsoft Academic Search

It is widely accepted that the global warming will impact on water resources. This study investigates the possible influence of climate change on the water resources in an alpine region. A description of the actual situation with emphasis on the water resources from the one side and on the water consuming factors, here called stressors, is given. The probable effects

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

2008-01-01

336

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

EPA Science Inventory

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

337

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

338

Exploring large-scale atmospheric influences on high river flow clustering in the UK  

NASA Astrophysics Data System (ADS)

Following several recent, large-scale flood events in the UK (including central and eastern England in Easter 1998; northern England in autumn 2000; northern and central England in 2007; and Scotland and northern England in 2009), research to explain their occurrence has shifted away from "searching for a trend". Instead, new studies have demonstrated that in the UK, high river flows are temporally clustered into flood-rich and flood-poor periods over decadal time-scales (e.g. Lane, 2008; Wilby et al., 2008; Raven et al., in prep) which may lead to under or over-estimation of event probabilities (Khaliq et al., 2006). Understanding the spatial and temporal occurrence of large-scale flood events is important for flood frequency estimation for policy-making, risk management and the insurance industry. We combine knowledge and techniques from hydrology and meteorology to: (1) demonstrate the presence of decadal and multi-decadal length flood-rich and flood-poor periods; and (2) identify their causes using simple predictor variables that allow us to introduce time-dependence into event probabilities. Our approach uses analysis of river flow time-series using the longest available records in the UK, to create peak over threshold series for 21 locations. We analyse the clustering of yearly counts of peak river flows by testing a dispersion statistic given by the ratio of variance and mean of the counts. It is found that the dispersion statistic exhibit clear-cut regional patterns, with statistically significant overdispersion occurring in most stations located on rivers in Central UK and large overdispersion characterising the peak series near the area of London. The statistical dependence of peak river flows from atmospheric and climatic patterns is analysed by Poisson regression where the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Southern Oscillation are used as covariates. The AMO is found to have a positive effect on the yearly rate of occurrence of peaks for the rivers in Wales, whereas the NAO has a negative effect for the rivers in Central UK. These climatic patterns, however, do not explain the large overdispersion of the rivers in the London area. Aggregating peak counts from rivers in the same geographical area yields a strongly enhanced overdispersion: this is shown to be due to spatial correlation of the processes leading to the occurrence of peak river flows.

Raven, Emma; Vitolo, Renato; Lane, Stuart; Stephenson, David

2010-05-01

339

Local and regional contributions to photochemical atmospheric pollution in southern France  

NASA Astrophysics Data System (ADS)

In France, an important air quality surveillance network is organized by region. Each region has a number of measurement sites available. In southern France for each region studied, measurement sites show highly correlated variations of daily ozone maxima during the summer periods (from April to September). Thus, we can calculate a mean regional distribution representative of each region considered. We can notice a high level of correlation between mean regional distributions for different regions. The Marseilles and Martigues areas are neighboring regions that show high correlation between each other, but rather low with other regions. We observe in these two areas high levels of ozone and primary pollutants. This seems to be the result of phenomena from different scales. Indeed, at meso-scale, the land/sea breeze effect coupled with daily erosion of the stable layer brings ozone and sulfur dioxide polluted air masses over the ground. Lastly, at a synoptic scale, a Scandinavian anticyclone, spreading out over Western Europe and drifting over the European continent, seems to be necessary and sufficient to the formation of ozone episodes in the Marseilles and Martigues regions.

Pont, Véronique; Fontan, Jacques

340

Regional variation of climatic influences on west nile virus outbreaks in the United States.  

PubMed

The national resurgence of human West Nile virus (WNV) disease in 2012 raised questions about the factors responsible for WNV outbreaks. Interannual climatic variations may influence WNV amplification and transmission to humans through multiple pathways, including mosquito breeding habitats, gonotrophic cycles, extrinsic incubation, avian communities, and human behavior. We examined the influences of temperature and precipitation anomalies on interannual variation in human WNV cases in three regions of the United States. There were consistent positive influences of winter temperatures, weaker and more variable positive effects of spring and summer temperatures, and highly variable precipitation effects that ranged from positive to negative. The overwintering period may be a particularly important climatic constraint on the dynamics of WNV in cold-temperate regions of North America. Geographic differences in the seasonal timing and relative importance of climatic drivers of WNV risk likely reflect underlying variability in key ecological and social characteristics. PMID:25092814

Wimberly, Michael C; Lamsal, Aashis; Giacomo, Paolla; Chuang, Ting-Wu

2014-10-01

341

Regional Variation of Climatic Influences on West Nile Virus Outbreaks in the United States  

PubMed Central

The national resurgence of human West Nile virus (WNV) disease in 2012 raised questions about the factors responsible for WNV outbreaks. Interannual climatic variations may influence WNV amplification and transmission to humans through multiple pathways, including mosquito breeding habitats, gonotrophic cycles, extrinsic incubation, avian communities, and human behavior. We examined the influences of temperature and precipitation anomalies on interannual variation in human WNV cases in three regions of the United States. There were consistent positive influences of winter temperatures, weaker and more variable positive effects of spring and summer temperatures, and highly variable precipitation effects that ranged from positive to negative. The overwintering period may be a particularly important climatic constraint on the dynamics of WNV in cold-temperate regions of North America. Geographic differences in the seasonal timing and relative importance of climatic drivers of WNV risk likely reflect underlying variability in key ecological and social characteristics. PMID:25092814

Wimberly, Michael C.; Lamsal, Aashis; Giacomo, Paolla; Chuang, Ting-Wu

2014-01-01

342

Identifying the European fossil fuel plumes in the atmosphere over the Northeast Atlantic Region through isotopic observations and numerical modelling.  

PubMed

As part of the Danish NEAREX project the origin and variability of anthropogenic atmospheric CO(2) over the Northeast Atlantic Region (NEAR) has been studied. The project consisted of a combination of experimental and modelling activities. Local volunteers operated CO(2) sampling stations, built at University of Copenhagen, for (14)C analysis at four locations (East Denmark, Shetland Isles, Faroe Isles and Iceland). The samples were only collected during winter periods of south-easterly winds in an attempt to trace air enriched in fossil-fuel derived CO(2) due to combustion of fossil fuels within European countries. In order to study the transport and concentration fields over the region in detail, a three-dimensional Eulerian hemispheric air pollution model has been extended to include the main anthropogenic sources for atmospheric CO(2). During the project period (1998-2001) only a few episodes of transport from Central Europe towards NEAR arose, which makes the data set for the evaluation of the method sparse. The analysed samples indicate that the signal for fossil CO(2), as expected, is largest (up to 3.7+/-0.4% fossil CO(2)) at the Danish location closest to the European emissions areas and much weaker (up to approximately 1.5+/-0.6% fossil CO(2)) at the most remote location. As the anthropogenic signal is weak in the clean atmosphere over NEAR these numbers will, however, be very sensitive to the assumed background (14)CO(2) activity and the precision of the measurements. The model simulations include the interplay between the driving processes from the emission into the boundary layer and the following horizontal/vertical mixing and atmospheric transport and are used to analyse the meteorological conditions leading to the observed events of high fossil CO(2) over NEAR. This information about the history of the air masses is essential if an observed signal is to be utilised for identifying and quantifying sources for fossil CO(2). PMID:16917720

Geels, C; Christensen, J H; Hansen, A W; Heinemeier, J; Kiilsholm, S; Larsen, N W; Larsen, S E; Pedersen, T; Sørensen, L L; Brandt, J; Frohn, L M; Djurhuus, S

2006-06-01

343

Influence of asian dusts on the physicochemical properties of atmospheric aerosols in taiwan district — using the penghu islands as an example  

Microsoft Academic Search

Using the Penghu Islands as an example, this study investigates the influence of Asian dusts on the physicochemical properties of atmospheric aerosols in Taiwan District in the year of 2002. An aerosol-sampling site was established at Xiaumen, the Penghu Islands, to collect sea level atmospheric aerosols for further analysis of their physicochemical properties. This study revealed that, during the sampling

Chung-Shin Yuan; Cheng-Chung Sau; Ming-Chung Chen

2004-01-01

344

Deposition and transport of atmospheric mercury and other HAPS in the Great Lakes region  

SciTech Connect

To investigate the levels and atmospheric transport of hazardous air pollutants (HAPS) a network of event precipitation and ambient monitoring sites was established in Michigan. Measurements of vapor and particulate mercury, trace elements, as well as a number of organochlorine compounds (OCs) including PAHs, PCBs, and selected pesticides were made at four locations in Michigan. Measurements performed in the network from 1992--1994 are discussed together with meteorological data gathered concurrently. Seasonal variations in the levels and deposition of mercury and other compounds are discussed in relation to their sources and dominant transport corridors. The transport of HAPs into and out of Michigan is investigated using calculated air mass trajectories and associated meteorological parameters. The relationship between atmospheric mercury, other trace metals, and OCs will be discussed. The paper will discuss this unique data base in a comprehensive way for the first time.

Keeler, G.J.; Hoyer, M.

1994-12-31

345

Atmospheric Lithosphere-Ionosphere Charge Exchange (ALICE) for coupling between earthquake regions, clouds and the ionosphere  

NASA Astrophysics Data System (ADS)

Atmospheric Lithosphere-Ionosphere Charge Exchange (ALICE) has been proposed as a mechanism to link seismic activity and ionospheric changes detected overhead, which has been observed in data obtained by the DEMETER spacecraft. The ALICE mechanism can explain changes in the natural extremely low frequency (ELF) radio noise observed by DEMETER nocturnally before major earthquakes. ALICE operates through the vertical fair weather current density of global atmospheric electricity, through the modification of surface layer ionisation rates and the associated current flow to the ionosphere. These ideas are extended here to include possible effects on layer clouds through which the current density passes. Specifically, we estimate possible layer cloud changes for changes in surface layer ionisation known in some earthquakes.

Harrison, Giles; Aplin, Karen; Rycroft, Michael

2014-05-01

346

Upscaling and Downscaling—A Regional View of the Soil–Plant–Atmosphere Continuum  

Microsoft Academic Search

pixel will contain several vastly different surfaces: bare soil, standing water, vegetation, parking lots, etc. How The strength of interaction among soil, plants, and atmosphere does one assign appropriate values to bulk model pa- depends highly on scale. As the spatial scale of organized soil-plant behavior (e.g., soil drying and\\/or stomatal closure) increases, so does rameters associated with strongly heterogeneous

Martha C. Anderson; William P. Kustas; John M. Norman

2003-01-01

347

Formaldehyde in Various Forms of Atmospheric Precipitation and Deposition from Highly Urbanized Regions  

Microsoft Academic Search

Formaldehyde levels were determined in various forms of atmospheric precipitation (rain, snow, road and roof runoff, throughfall)\\u000a and deposition (rime, hoarfrost, dew) collected over twelve months at various locations in two large urban agglomerations\\u000a and along two highways. HCHO was found in 303 of 500 samples analyzed, with concentrations ranging from 0.05 to 10.7 mg\\/dm3. The results confirmed the significant

?aneta Polkowska; Kamila Skar?y?ska; Tadeusz Górecki; Jacek Namie?nik

2006-01-01

348

Duplication in a shock tube of stagnation region conditions on a Jovian atmosphere-entry probe  

NASA Technical Reports Server (NTRS)

Measurements are presented of the radiative emission from a shock-heated mixture of .85 H2 plus .15 He - the presumed composition of the dominant species in the Jovian atmosphere. The experiments were performed behind the incident wave in a Voitenko-compressor-driven shock tube at shock velocities of 61 and 67 km/sec. Agreement with predictions is good for both radiative emission and radiative cooling.

Compton, D. L.; Cooper, D. M.

1973-01-01

349

Atmospheric cycling and air-water exchange of mercury over mid-continental lacustrine regions  

Microsoft Academic Search

Atmospheric mobilization and exchange at the air-water interface are significant features of biogeochemical cycling of Hg\\u000a at the Earth's surface. Our marine studies of Hg have been extended to terrestrial aquatic systems, where we are investigating\\u000a the tropospheric cycling, deposition and air-water exchange of Hg in the mid-continental lacustrine environs of northcentral\\u000a Wisconsin. This program is part of a multidisciplinary

William F. Fitzgerald; R. P. Mason; G. M. Vandal

1991-01-01

350

Atmospheric distribution and deposition of mercury in the Idrija Hg mine region, Slovenia.  

PubMed

The atmospheric distribution and deposition of Hg in the area of the former Idrija Hg-mine, Slovenia, were investigated. Mapping of air Hg(0) concentrations was performed to assess the spatial distribution and major sources of mercury to the atmosphere in the area. In addition, analyses of mercury speciation in the air over Idrija were performed during a 4-day sampling campaign in September 2006 to better understand the fate and transformation of Hg in the atmosphere of this specific mercury polluted site. The speciation results were then compared to the results of mercury speciation in the wet and throughfall deposition sampled on a precipitation event basis from October 2006 to September 2007. The Hg(0) concentration in air was mostly below 10 ng m(-3), with the highest concentration in the area of the former smelter complex exceeding 5000 ng m(-3). Mercury-bearing airborne particles (TPM) seem to dominate the atmospheric Hg deposition, which revealed noticeable variations between precipitation events (11-76 ng m(-2)day(-1)), mostly as a function of the amount of precipitation. Hg in precipitation was largely (? 50%) associated with the particulate phase (THg(P)). No correlation was found between the THg(P) and the dissolved phases (THg(D)), suggesting that particulate phase Hg is mostly the result of dry deposition. In the throughfall, significantly higher (2-10 fold) Hg concentrations than in associated event precipitation were observed, mostly due to Hg in the particulate phase (? 70% THg). As shown by SEM/EDXS microscopy, an important amount of mercury in the precipitation and throughfall samples is due to the presence of cinnabar particles as a result of the aeolian erosion of cinnabar-containing surfaces in the area. PMID:21112585

Kocman, David; Vre?a, Polona; Fajon, Vesna; Horvat, Milena

2011-01-01

351

Investigation of Health Risks and Their Prevention in the Rapid Climate Changes and the Rise of Pollution of the Atmosphere in the Mountain Region of the North Caucasus  

NASA Astrophysics Data System (ADS)

The current global climate change is determined by changes in the structure of weather conditions, whose impact on the health of various regions of the planet has not been studied sufficiently. To study this effect on the low-altitude mountains resort of Kislovodsk (southern Russia) multi-factor assessment of the impact of the environment on human health is carried out. There were taking in account atmosphere condition, atmospheric aerosol pollution relationship with atmospheric circulation, the level of pollution matching with different types of weather, and, on the base of analysis of meteopathic reactions (MPR), the extent of their biotropism was revealed. Two sides of weather-climatic influences - specific and nonspecific - are interconnected. They manifest themselves differently in humans with different levels of regulation of vital activity and the adaptive capacity of the organism to the complex environmental effects. This complicates the precise physiological basis of quantitative criteria for the prediction of "biotropic" (adverse) weathers. Nevertheless, clinical observations have shown the existence of the "limiting" physiological bound on the size of medical-meteorological modules (MMM). The reactions of the organism to unfavorable weather factors on the results of a questionnaire monitoring surveillance of patients treated in clinics of Federal State Institution "Pyatigorsk State Research Institute of Curortology, FMBA of Russia" (PSRIC), in comparison with clinical data, have identified various MPR of the organism, the clinical manifestation of which depends on age, sex of the patient, the availability of principal and attendant pathology, reactivity, etc. Analysis of the results of clinical observation, cases of medical aid appealability to the station an ambulance at the sudden ill health, as well as the uptake of advice of sick people among immigrants during their short stay at the resort, and the local population, allowed the first approximation to clarify the criteria for "pathogenicity" of various weather conditions and the factors of air pollution. These criteria were put in a new technology of the Medical Weather Forecast (MWF). In this technology it is proposed to use the integrated Weather Pathogenicity Index (WPI), which is calculated as a weighted average of biotropism indices of various MMM, which include: the dynamics and day to day variability of temperature, pressure and humidity, wind speed, weight content of oxygen and natural air ions in the surface atmosphere, cloudiness, atmospheric phenomena, geomagnetic activity, the ultraviolet index (by UVB solar radiation), the integrated illumination by the sun, the heat conditions of the human. For each of the MMM the five physiological grades of the effects of weather on human adaptation to weather of magnitude and dynamics of WPI are marked out: indifferent, weak, moderate, harsh and overly harsh, according to which the degree of "pathogenicity" of the weather is estimating. Pathogenicity is indicated by quantitative number of medical types of weather (I - a very good weather, II - good weather, III - adverse weather, and IV - a particularly adverse weather). According to the forms of the pressure relief on the sea level, 850 hPa, and 500 hPa, the nature of atmospheric stratification and the presence of atmospheric fronts in the medical types of weather the type of atmospheric circulation is evaluating (anticyclonic - "A", cyclonic - "B", frontal - "C"), which defines a subtype of weather and the possible nature of meteopathia (hypotensive, hypoxic, spastic, etc.). Innovations of the new technology are associated with the introduction of a methodology for the preparation of MWF the modified classifiers to determine the gradation of biotropism degree for various MMM, confirmed by the results of comprehensive empirical medical and climatic studies using dynamic and synoptic weather forecasting making by Hydrometeocenter of Russia and forecast of atmospheric pollution

Babyakin, Alexander; Polozkov, Igor; Golitsyn, Georgy; Efimenko, Natalia; Zherlitsina, Liubov; Povolotskaya, Nina; Senik, Irina; Chalaya, Elena; Artamonova, Maria; Pogarski, Fedor

2010-05-01

352

Validation of vertical profile from atmosphere using ATOVS products and its impact over Indian region.  

NASA Astrophysics Data System (ADS)

This research paper summarizes the validation of atmospheric vertical profile using NOAA(National Oceanic and Atmospheric Administration)/ MetOp satellite derived data over India with radiosonde observations over a span of 8 months. NOAA's International Advanced Television and Infrared Observations satellite Vertical Sounder (ATOVS) processing package (IAPP) obtains temperature and moisture profiles in different pressure levels ranging from 1000hpa to 10hpa from real time direct broadcast (DB) receiving system installed at India Meteorological department. Different pressure levels were substituted to the same pressure levels for calculations of standard deviation, bias and RMSE (root mean square error) The sounder derived products like Total precipitable water vapor (TPW) and Lifting index(LI) from NOAA Satellite was also validated with radiosonde data which provided significant results for weather forecasting. The validation shows that the sounder provides unique information about the state of atmosphere and monitoring the convective environment for severe weather forecasting In addition to this, case study on severe weather events was analyzed using ATOVS products.

Mahandru, Riddhi; Kumar, Adarsh; Mitra, Ashim kumar

353

Trans-Pacific and regional atmospheric transport of anthropogenic semivolatile organic compounds in the Western United States  

NASA Astrophysics Data System (ADS)

The atmospheric transport of anthropogenic semivolatile organic compounds (SOCs) from Asian sources to the Western U.S. was investigated. In addition, the SOC extraction method was optimized. Hansen solubility parameter plots were used to aid in the pressurized liquid extraction (PLE) solvent selection of air sampling media in order to minimize polymeric matrix interferences. To estimate the emissions of anthropogenic semivolatile organic compounds (SOCs) from East Asia and to identify unique SOC molecular markers in Asian air masses, air samples were collected on the island of Okinawa, Japan in Spring 2004. Elevated concentrations of hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and particulate-phase polycyclic aromatic hydrocarbons (PAHs) were attributed to air masses from China. A large proportion of the variation in the current use pesticides, gas-phase PAHs, and polychlorinated biphenyl (PCB) concentrations was explained by meteorology. Using measured PAH, carbon monoxide (CO), and black carbon concentrations and estimated CO and black carbon emission inventories, the emission of 6 carcinogenic particulate-phase PAHs were estimated to be 1518-4179 metric tons/year for all of Asia and 778-1728 metric tons/year for only China. Atmospheric measurements of anthropogenic SOCs were made at Mt. Bachelor Observatory (MBO), located in Oregon's Cascade Range. PAH concentrations at MBO increased with the percentage of air mass time in Asia and, in conjunction with other data, provided strong evidence that particulate-phase PAHs are emitted from Asia and undergo trans-Pacific atmospheric transport to North America. Enhanced HCB, alpha-HCH, and gamma-HCH concentrations also occurred during trans-Pacific atmospheric transport, compared with regional (Western U.S.) air masses during similar time periods. Gas-phase PAH and fluorotelomer alcohol (FTOH) concentrations significantly increased with the percentage of air mass time in California's urban areas, while retene and PCB concentrations increased with the percentage of air mass time in Oregon and during regional fire events. Regional atmospheric transport in the Western U.S. also resulted in enhanced gamma-HCH, dacthal, endosulfan, metribuzin, triallate, trifluralin, and chlorpyrifos concentrations, with episodic concentration enhancements during spring application periods. Elevated SigmaPCB, Sigmachlordane, HCHs, HCB, and trifuralin concentrations were also associated with fires, which may be due to volatization of pesticides deposited to soils and vegetation.

Primbs, Toby

354

Evaluation of temperature and wind over Antarctica in a Regional Atmospheric Climate Model using 1 year of automatic weather station data and upper air observations  

Microsoft Academic Search

The Regional Atmospheric Climate Model version 2 (RACMO2\\/ANT) is used to simulate the Antarctic atmosphere for the year 1998. The parameterizations of the physical processes in the model are taken from the European Centre for Medium-Range Weather Forecasts (ECMWF) global model and adapted to better represent the specific conditions over the Antarctic continent. The snow albedo was increased by decreasing

C. H. Reijmer; E. van Meijgaard; M. R. van den Broeke

2005-01-01

355

Atmospheric trace element and major ion concentrations over the eastern Mediterranean Sea: Identification of anthropogenic source regions  

NASA Astrophysics Data System (ADS)

Concentrations of elements and ions measured in aerosol samples collected from March 1992 to the end of December 1993 were investigated to identify source regions affecting chemical composition of aerosols in the eastern Mediterranean atmosphere. Collected samples were analyzed for approximately 40 elements and ions using a combination of atomic absorption spectrometry, instrumental neutron activation analysis, ion chromatography and colorimetry. Statistical techniques, such as enrichment factors and a non-parametric bootstrapped potential source contribution function, were applied on the data set to determine main source types and source regions of anthropogenic particles in the eastern Mediterranean basin. Source regions of two previously defined anthropogenic components, namely a long-range transported component and a local pollution component, were identified. The main source areas for pollutants reaching the eastern Mediterranean basin were determined as southern and western parts of Turkey, central and eastern regions of Ukraine, east of Belarus, Greece, Georgia, Romania, coastal areas along France and Spain and coastal areas around the Black Sea, Russia. More distant source regions in the South of UK and Sweden, the central part of Algeria, the northeastern part of Turkey, Russia, Germany, Hungary, Czech Republic, Bosnia and Herzegovina, and coastal areas of Egypt, Israel and Italy do affect aerosol composition in the eastern Mediterranean, but transport from these regions cannot account for the highest 20% of the measured pollutant concentrations.

Güllü, Gülen; Do?an, Güray; Tuncel, Gürdal

356

Influences of atmospheric conditions and air mass on the ratio of ultraviolet to total solar radiation  

SciTech Connect

The technology to detoxify hazardous wastes using ultraviolet (UV) solar radiation is being investigated by the DOE/SERI Solar Thermal Technology Program. One of the elements of the technology evaluation is the assessment and characterization of UV solar radiation resources available for detoxification processes. This report describes the major atmospheric variables that determine the amount of UV solar radiation at the earth's surface, and how the ratio of UV-to-total solar radiation varies with atmospheric conditions. These ratios are calculated from broadband and spectral solar radiation measurements acquired at SERI, and obtained from the literature on modeled and measured UV solar radiation. The following sections discuss the atmospheric effects on UV solar radiation and provide UV-to-total solar radiation ratios from published studies, as well as measured values from SERI's data. A summary and conclusions are also given.

Riordan, C.J.; Hulstrom, R.L.; Myers, D.R.

1990-08-01

357

A new view of the solar outer atmosphere by the Transition Region and Coronal Explorer  

E-print Network

temperature than the outer domains. Subject headings: Sun: activity, Sun: corona, Sun: coronal heating #12 of the corona, the larger­scale thermal trends, the evolution of the corona over quiet and active regions and structure of the conductively dominated transition region between chromosphere and corona, loop oscillations

Schrijver, Karel

358

REGIONAL ATMOSPHERIC CIRCULATION AND SURFACE TEMPERATURES PREDICTING COTTON YIELDS IN THE SOUTHEASTERN USA  

Microsoft Academic Search

Research has shown strong relationship s between ENSO phase and climate in the southeastern USA during the boreal winter. Crop yields in this region are significantly affected by ENSO phase due to predictable patterns of climate during this time of the year. However, both climate during the boreal summer months and cotton yields in this region show little or no

Guillermo A. Baigorria; James W. Hansen; Neil Ward; James W. Jones; James J. O'Brien

359

The influence of the growth of the Dallas/Fort Worth (DFW) Metroplex on regional precipitation patterns  

E-print Network

regions. Previous research has shown that cities can influence regional precipitation patterns. This is a result of many factors such as: increased heating and lifting caused by the urban heat island effect (UHI), increased pollution and aerosols...

Nordfelt, Anna Marie

2009-05-15

360

Inferences on the thermodynamic characteristics of a star from the observed distinctive radial sequences of the distinctive atmospheric regions comprising that stellar atmosphere  

SciTech Connect

The implications of observational findings on atmospheric and subatmospheric taxonomy, diagnostics, and modeling are explored. The correlations between distinctive radial sequences in stellar atmospheres and the thermodynamic properties of the stars in which they appear are discussed.

Not Available

1983-01-01

361

Characteristics Of Atmospheric Dry Deposition Of Metals To The Region Of Lake Asan And Sapgyo, Korea  

NASA Astrophysics Data System (ADS)

Environment includes a multi-media such as air, surface water, soil, underground water and ecosystem. Some pollutants transfer among a multi-media, posing serious threat to humans, animals and plants. Pollutants released into the environment remain for long times and transport long distances while going through physical and chemical interactions such as transports between multi-media ; air, water and soil, deposition, and absorption and release from organisms. This study assessed the amount of heavy metals transferred from air to water and soil using dry deposition plate and water surface sampler during spring (June 13 ~ 21, 2007) and winter (October 23 ~ 30 in 2007) at 9 locations including Dangjin, Pyeongtaek and Asan. Micro-Orifice Uniform Deposit Impactor, MOUDI was used to confirm the size distribution. The measured heavy metal deposition flux was compared with the expectation obtained with deposition model. In addition, amount of heavy metal deposition at Asan and Sapgyo lakes were evaluated to verify the water pollution state driven by atmospheric deposition. Atmospheric dry deposition flux of metals are 133.92 microgram m-2 day-1, 44.01 microgram m-2 day-1, 0.915 microgram m-2 day-1, and 0.175 microgram m-2 day-1 during spring, and 72.86 microgram m-2 day- 1, 88.14 microgram m-2 day-1, 0.991 microgram m-2 day-1, and 0.189 microgram m-2 day-1 during fall, for lead, nickel, arsenic, and cadmium, respectively. It is required to re- calculation the dry deposition flux by land use type due to possibility of underestimating the flux in case of using grease surrogate surface having low surface roughness. The cadmium, lead, and arsenic size distribution was mono-modal with the peaks in the 0.65 ~ 1.1 micrometer size range in the fine mode showing sharp peak in the condensation submode especially for cadmium and lead because of effect of primary emission. The nickel size distribution was bimodal, a typical size distribution for an urban atmosphere, showing sharp peak in the condensation submode affected by primary emission and coarse mode. Total atmospheric dry deposition loads of metals to the Lake Asan and Sapgyo are 1272.6 ~ 1764.1 g day-1, 655.3 ~ 908.3 g day-1, and 137.2 ~ 190.1 g day-1 during spring, and 6914.1 ~ 9583.8 g day-1, 849.2 ~ 1177.1 g day-1, and 79.2 ~ 109.8 g day-1 during fall, for lead, nickel, and arsenic, respectively. Total flux of atmospheric pollution could be calculated later by adding the result of wet deposition which is the major atmospheric transport of pollution.

Han, J.; Shin, H.; Lee, M.; Lim, Y.; Seo, M.; Jung, I.

2008-12-01

362

Cool regions in relativistic plasmas - Thermal instabilities. [applicable to quasar atmospheres and radio galaxies  

NASA Technical Reports Server (NTRS)

The thermal stability of a plasma consisting of dynamically dominant relativistic electrons and a warm inertial gas is studied. Bremsstrahlung, Coulomb, synchrotron, and inverse Compton losses are considered; it is found that plasmas in which the cooling is dominated by either of the first two processes are generally unstable, while synchrotron losses may or may not cause instability and inverse Compton losses are stabilizing. Characteristic growth times and unstable scales are determined from linear analysis. Applications of this instability to quasar atmospheres and to extended radio galaxies are discussed briefly.

Eilek, J. A.; Caroff, L. J.

1979-01-01

363

Seasonal variation of atmospheric Pb-210 and Al in the western North Pacific region  

NASA Astrophysics Data System (ADS)

The atmospheric concentrations of Pb-210 over a period of two years were determined from aerosol samples collected at six stations in the western North Pacific. The results are compared with those for Al, showing that, although Pb-210 concentrations vary widely from week to week, the degree of variation is about half of that for Al. For Pb-210, the year-to-year variation is not pronounced and the seasonal variation is well represented by a sine curve. The results suggest that Pb-210 has a longer residence time than Al, because Pb-210 is transported through higher altitudes and is deposited more evenly onto the earth's surface and the ocean.

Tsunogai, Shizuo; Kurata, Takayoshi; Suzuki, Toshitaka; Yokota, Kiichiro

1988-11-01

364

Changes in atmospheric CO2 - Influence of the marine biota at high latitude  

Microsoft Academic Search

Approximately half of the nitrogen and phosphorus entering deep waters of the contemporary ocean are transported from the surface in inorganic form as preformed nutrients. A simple model for ocean chemistry is presented and shown to account for the present level of atmospheric CO2. Fluctuations in preformed nutrients, modulated by changes in insolation and circulation at high latitudes, can result

Fanny Knox; M. B. McElroy

1984-01-01

365

Influence of atmospheric and system parameters on multiple scattering in spaceborne backscatter lidar measurements  

Microsoft Academic Search

We have simulated backscatter signals of spaceborne lidar systems with the help of a Monte Carlo model. Calculations were performed for various combinations of system parameters. As typical examples of atmospheric observation targets, two kinds of cirrus cloud and two kinds of aerosol were considered. Both total multiple scattering and the significance of individual higher scattering orders are discussed. For

Peter Völger; Andrew Y. S. Cheng; Nobuo Sugimoto

2005-01-01

366

Hadron Generator and Atmospheric Seasonal Variation Influence on Cosmic Ray Ionization computed with CORSIKA Code  

E-print Network

Recently an essential progress in development of physical models for cosmic ray induced ionization in the atmosphere is achieved. Basically, the models are full target, i.e. based on Monte Carlo simulation of an electromagnetic-muon-nucleon cascade in the atmosphere. In general, the contribution of proton nuclei in those models is highlighted, i.e. primary cosmic ray $\\alpha$-particles and heavy nuclei are neglected or scaled to protons. The development of cosmic ray induced atmospheric cascade is sensitive to the energy and mass of the primary cosmic ray particle. The largest uncertainties in Monte Carlo simulations of a cascade in the Earth atmosphere are due to assumed hadron interaction models, the so-called hadron generators. In the work presented here we compare the ionization yield functions $Y$ for primary cosmic ray nuclei, such as protons, $\\alpha$-particles, Oxygen and Iron nuclei, assuming different hadron interaction models. The computations are fulfilled with the CORSIKA 6.9 code using GHEISHA 2...

Mishev, A

2014-01-01

367

Influence of the hadronic interaction model on the calculation of the atmospheric muon flux  

Microsoft Academic Search

We report in this work a comparison between Monte Carlo simulations of the atmospheric muon differential fluxes performed with the air shower code CORSIKA and their corresponding measurements obtained by the BESS experiment. As input, we have used the primary fluxes of protons and helium nuclei parameterized by the force field model for a given loca l interstellar spectra. The

Taoufik Djemil; Reda Attallah

368

Sound propagation over ground under the influence of a sound speed profile in the atmosphere  

Microsoft Academic Search

Sound propagation from a monopole point source located over a semi-infinite porous ground is investigated. The atmosphere is described as a generalized horizontally stratified medium in order to take vertical variations in the sound speed into account. In each layer a linearly varying sound speed is permitted, hence making it possible to simulate a piecewise linear vertical velocity variation. The

K. B. Rasmussen

1990-01-01

369

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

E-print Network

deposition. TM and Dissolved Organic Carbon (DOC) physical fractionation between colloidal and truly canopy interaction with atmospheric inputs, TM were measured in both Open Field Bulk Deposition (BD dissolved phases was performed with ultrafiltration. Al, Fe, Pb and Cu are found in the colloidal fraction

Mailhes, Corinne

370

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

Microsoft Academic Search

Although soil erosion has often been considered a net source of atmospheric carbon (C), several recent studies suggest that erosion serves as a net C sink. We have developed a spreadsheet-based model of soil organic C dynamics within an eroding profile (Soil Organic Carbon, Erosion, Replacement, and Oxidation (SOrCERO)) that calculates effects of soil organic carbon (SOC) erosion and altered

S. A. Billings; R. W. Buddemeier; D. de B. Richter; K. Van Oost; G. Bohling

2010-01-01

371

Influence of atmospheric pressure plasma treatment on various fibrous materials: Performance properties and surface adhesion analysis  

Microsoft Academic Search

Atmospheric pressure plasma treatment using oxygen gas was applied to wool fibrous materials. The plasma-treated fibrous materials were characterised using advanced instrumental techniques including scanning electron microscopy and X-ray photoelectron spectroscopy. They were also tested for performance properties including tensile and tearing strength as well as change in yellowness using international standard testing methods. Wettability analysis was conducted to study

S. Y. Cheng; C. W. M. Yuen; C. W. Kan; K. K. L. Cheuk; W. A. Daoud; P. L. Lam; W. Y. I. Tsoi

2010-01-01

372

Influence of the atmosphere on remotely sensed reflection from vegetation surfaces  

SciTech Connect

Multiple scattering of solar radiation in a vegetation canopy is modelled equivalent to absorbing and scattering in a turbid medium with direction-dependent cross sections. Perturbations of plant reflection patterns due to atmospheric effects are computed at different altitudes and compared to the angular reflection characteristics caused by Lambertian surfaces of varying albedoes.

Simmer, C.; Gerstl, S.A.W.

1985-01-01

373

Influence of outflow from the Gulf of Mexico region on NMHC composition of the free and upper troposphere over Europe and the North Atlantic  

NASA Astrophysics Data System (ADS)

The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container; www.caribic-atmospheric.com) involves the deployment of an instrument container equipped to make atmospheric measurements from aboard a passenger jet, and has operated since 2005 from aboard a Lufthansa Airbus 340-600. Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. A suite of 20 non-methane hydrocarbons (NMHCs) are measured from the whole air samples, along with greenhouse gas and halocarbon measurements. As all flights originate in and return to Frankfurt, Germany, the free and upper troposphere (FT/UT) over Europe and the North Atlantic are probed on nearly every flight, and the composition was found to be strongly influenced by air masses from the Gulf of Mexico region. Over 75% of air samples collected during flight had backwards trajectories which passed over the region, and nearly half of these had passed through the lower troposphere and boundary layer, affording CARIBIC a "bird's-eye view" of emissions from the Gulf region. Measurements of NMHCs, and also methane, show distinct fossil fuel extraction signatures for Gulf region outflow, namely relatively large enhancements in C2-C4 alkanes coupled with unique ratios between species. Here we discuss the impact of these emissions and their subsequent chemical transformations on FT/UT composition. We also investigate the possible influence of these emissions on the increase in C2-C4 alkanes observed in the FT/UT by CARIBIC over the last 7 years.

Baker, A. K.; Schuck, T. J.; Rauthe-Schöch, A.; Brenninkmeijer, C. A.

2012-12-01

374

A TW in Mars' Atmosphere and Implications for the Aerobraking region  

NASA Astrophysics Data System (ADS)

A solar terminator wave (TW) is found in high-resolution general circulation model (GCM) simulations of Mars' atmosphere. In the horizontal plane at 160 km the wave fronts precede the westward-moving dusk terminator, exhibit a horizontal wavelength of order 15°-30° or 900-1800km, and are oriented about 10°-30° with respect to the terminator. The disturbance originates in the lower atmosphere due to dust insolation absorption, propagates upward with an effective vertical wavelength of order 60 km, and increases in amplitude as the dust extends further away from the surface. The TW density amplitudes for low and elevated dust layers (both with opacities = 1.0) are of order ± 15-20% and ± 30% at 160 km, which are sufficiently large to pose a concern for aerobraking operations. Temperature and wind perturbations for the former case are of order ± 10-20 K and ± 30-75 m/s. The Mars TW shares many common features with a TW recently observed in Earth's thermosphere and simulated with a GCM.

Moudden, Y.; Forbes, J.

2009-05-01

375

Atmospheric surface layer responses to the extreme lightning day in plateau region in India  

NASA Astrophysics Data System (ADS)

This paper discusses the observations of the atmospheric surface layer (ASL) parameters during the lightning event. During this event behaviour of surface layer parameters has been observed. Other derived parameters like Monin-Obukhov stability parameter (z/L), turbulent kinetic energy (TKE), momentum flux (MF) and sensible heat flux (SHF) have also been considered during this stochastic phenomenon. Characteristics of these surface layer parameters have been analysed during lightning period and compared with the clear weather day. During the peak period of the lightning, the incoming solar irradiance was reduced by one third of its normal value, resulting in an air-temperature decrement near the surface in the range of 4 °C to 6 °C. In addition to that a significant reduction in energy exchanges between surface and lower lying atmosphere (viz. TKE, MF and SHF), has also been observed. The rate of instantaneous decay in solar irradiance and SHF from the first strike to its peak strike time was larger than that seen during clear day hours. The normalized standard deviations of wind components during clear day were studied using Monin-Obukhov similarity theory (MOST) and the results have been compared with earlier studies reported in the literature.

Dwivedi, Arun K.; Chandra, Saga