Variations in 7Be concentrations in the atmosphere of Kuwait during the period 1994 to 1998

Al-Azmi, Darwish; Sayed, A.M; Yatim, H.A

doi:10.1016/s0969-8043(01)00077-x

Cited by 48 publications

(22 citation statements)

References 5 publications

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“…Given sample collection, the bulk deposition was transferred into a cleaned polyethylene bottle. Part of 7 Be may adsorb onto the equipment walls because it exists as BeO or Be(OH) 2 (Al-Azmi et al, 2001). Be dissolves in acid solution.…”

Section: Methodsmentioning

confidence: 99%

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

Zhang

Yang

Chen

et al. 2016

Aerosol Air Qual. Res.

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Be deposition and precipitation, existing in both northeast and southwest monsoon seasons, suggested the dominant removal of atmospheric 7 Be via precipitation. However, the correlations showed a large slope for the northeast monsoon season, indicating higher 7 Be contents in the atmosphere during the northeast monsoon prevailing months, supported by the precipitation-normalized 7 Be and the temporal variability of 7 Be/ 210 Pb ratios. Such a scenario revealed more intensive exchange of air mass between the stratosphere and troposphere during the northeast monsoon prevailing months. Together with the high pollutant concentrations in ambient air observed in these seasons, the results indicated that the pollutants in Xiamen might enter into the upper troposphere via vertical air mass exchange.

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Section: Methodsmentioning

confidence: 99%

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

Zhang

Yang

Chen

et al. 2016

Aerosol Air Qual. Res.

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“…7 Be is being observed in various monitoring networks worldwide and offers a reasonably well distributed set of data. We use the observations of the Environmental Measurement Laboratory (EML: http://www.nbl.doe.gov/ htm/EML Legacy Website/index.htm) combined with other studies (Al-Azmi et al, 2001;Cannizzaro et al, 2004;Elsässer et al, 2011;Gerasopoulos et al, 2001;Kulan et al, 2006;Pacini et al, 2011;Papastefanou and Ioannidou, 1996). This way we obtained 109 7 Be and 51 210 Pb observations.…”

Section: Surface Air Concentrationsmentioning

confidence: 99%

Influence of model resolution on the atmospheric transport of <sup>10</sup>Be

Heikkilä

Smith

2012

Atmos. Chem. Phys.

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Abstract. Understanding the transport path of the solar activity proxy 10 Be from source to archive is crucial for the interpretation of its observed variability. The extent of mixing of the strong production signal has been quantified in a previous study (Heikkilä et al., 2009). In this study we perform sensitivity studies to investigate the influence of model resolution on the degree of mixing and transport path of 10 Be in the atmosphere using the ECHAM5-HAM aerosol-climate model. This study permits us to choose an acceptable resolution, and so minimum CPU time, to produce reconstructions as physically accurate as possible. Five model resolutions are applied: T21L19: a coarse horizontal and vertical resolution with model top at ca. 30 km, T42L31: an average horizontal and fine vertical one, T42L39: similar vertical resolution than L19 but including the middle atmosphere up to ca. 80 km, T63L31: a fine horizontal and vertical resolution and T63L47: a fine resolution horizontally and vertically with middle atmosphere. Comparison with observations suggests that a finer horizontal and vertical resolution might be beneficial, producing a reduced meridional gradient, although the spread between observations was much larger than between the five model runs. In terms of atmospheric mixing the differences became more distinguishable. All resolutions agreed that the main driver of deposition variability, observed in natural archives, is the input of stratospheric 10 Be (total contribution 68 %) which is transported into the troposphere at latitudes 30-50 • . In the troposphere the model resolutions deviated largely in the dispersion of the stratospheric component over latitude. The finest resolution (T63L47) predicted the least dispersion towards low latitudes but the most towards the poles, whereas the coarsest resolution (T21L19) suggested the opposite. The tropospheric components of 10 Be differed less between the five model runs. The largest differences were found in the polar tropospheric components, which contribute the least to total production (≈ 4 %). We conclude that the use of the T42 horizontal resolution seems to be sufficient in terms of atmospheric mixing of a stratospheric tracer because no substantial improvement was seen when the resolution was increased from T42 to T63. The use of the middle atmospheric configuration is a trade-off between correctly describing stratospheric dynamics and having to reduce vertical resolution. The use of a high vertical resolution seemed more beneficial than the middle atmospheric configuration in this study. The differences found between the T42L31 and T63L31 resolutions were so small that T42L31 is a good choice because of its computational efficiency.

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“…Under especially favorable conditions (regularity of measurements of the meteorological parameters, absence of any effect due to some of them, and so forth), a correlation between the 7 Be content and the Wolf number can be determined reliably. Thus, measurements performed under the conditions of a dry and hot climate [7] showed that the changes of the yearly average volume activity of 7 Be depend on the Wolf number (Table 1). A correlation cannot be established under different, less favorable, conditions [8].…”

mentioning

confidence: 93%

“…Short-time flares with the highest Wolf number can sometimes be manifested as a sharp decrease of the 7 Be content in the atmosphere. Such an effect was observed in [6] (Fig.…”

mentioning

confidence: 99%

“…Almost immediately after they are formed, the 7 Be nuclei precipitate in submicron-size aerosols, and transport with air masses, settling, and washing out by precipitation determines their subsequent fate. The methods used to determine the life time of aerosols (the period of time during which half of the initial content of the aerosols is removed from the atmosphere) and the results obtained are presented in [9] together with data for other observation points (Greece, Germany, California, Hong Kong).…”

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confidence: 99%

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Content of cosmogenic 7Be in the air layer at the ground at temperate latitudes

et al. 2007

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The 7 Be content was measured in aerosols (once per week) and precipitation (once per month) was monitored as part of the monitoring of the radioactivity of the atmospheric layer near the ground in Rostovon-Don in 2001-2005. Data were obtained on the correlations between the 7 Be volume activity in aerosols and the Wolf number, temperature, and amount of precipitation. The highest correlation coefficients were observed during the spring (k = 1). It was determined that the volume activity of 7 Be changes in the second half of the 23rd cycle of solar activity, i.e., the yearly average 7 Be concentration increases toward the end of the cycle. Data were obtained on the seasonal dependence of the precipitation density and the volume activity of 7 Be on the meteorological parameters (temperature, amount of precipitation).Cosmogenic 7 Be (T 1/2 = 52.3 days) forms in nuclear spallation reactions when high-energy protons (∼1 GeV) when cosmic rays interact with nitrogen nuclei in the stratosphere 14 N + p → 7 Be (up to 70-80%) and secondary neutrons with nitrogen nuclei and oxygen in the troposphere 14 N + n → 7 Be and 16 O + n → 7 Be (up to 20-30%) [1,2]. During changes in the solar activity (number of sun spots -the Wolf number W) within the 11-year solar cycle and aperiodic bursts of solar activity, the geomagnetic field changes, cosmic rays are deflected and, correspondingly, the 7 Be production rate changes [3]. A decrease of the 7 Be production rate corresponds to an increase of solar activity (increase of the Wolf number) and vice versa, i.e., there is an anticorrelation between the 7 Be content in the atmospheric air and the Wolf number with coefficient k = −0.81 according to [4] and k = −0.83 ± 0.03 according to the data in [5]. Over the 11-year solar cycle, the yearly average content at the maximum and minimum differs by approximately 45%. The 7 Be production rate also depends on the geographical coordinates of the observations station because of the effect of the Earth's magnetic field on the cosmic ray distribution.Long (more than two cycles of solar activity) systematic measurements on the global network of stations must be performed in order to determine reliably the relation between the 7 Be volume activity in the air layer at the ground and the solar activity against the background of variations of a different origin. The results of the determination of 7 Be in the atmosphere in 1974-1999 at 26 stations were analyzed in [3]. The existence of the anticorrelation indicated above, which explains about 54% of all temporal variations of the 7 Be for stations in Australia, New Zealand, and North America and only 18% of the variations for the stations in South America and Antarctica, has been proven. Long-time measurements (1987Long-time measurements ( -2003 were performed recently at temperate latitudes (40°38′) [6]. Under especially favorable conditions (regularity of measurements of the meteorological parameters, absence of any effect due to some of them, and so forth), a correlation between the 7 Be content an...

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Variations in 7Be concentrations in the atmosphere of Kuwait during the period 1994 to 1998

Cited by 48 publications

References 5 publications

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

Influence of model resolution on the atmospheric transport of <sup>10</sup>Be

Content of cosmogenic 7Be in the air layer at the ground at temperate latitudes

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Variations in 7Be concentrations in the atmosphere of Kuwait during the period 1994 to 1998

Cited by 48 publications

References 5 publications

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

Influence of model resolution on the atmospheric transport of &lt;sup&gt;10&lt;/sup&gt;Be

Content of cosmogenic 7Be in the air layer at the ground at temperate latitudes

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Influence of model resolution on the atmospheric transport of <sup>10</sup>Be