Diurnal variation of ionization rate close to ground

Dhanorkar, Savita; Kamra, A. K.

doi:10.1029/94jd01335

Cited by 21 publications

(31 citation statements)

References 12 publications

(2 reference statements)

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“…The enhanced radon activity concentration causes the variation in the ionization rate, increasing the small ion concentrations observed near the ground at certain sites, especially where there is an accumulation of radon in the air 29,[36][37][38] . The ionization rate via radon decay is highly sensitive to the elevation from the ground, so it is larger closer to the ground 39 .…”

Section: Discussionmentioning

confidence: 99%

Subterranean atmospheres may act as daily methane sinks

et al. 2015

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In recent years, methane (CH 4 ) has received increasing scientific attention because it is the most abundant non-CO 2 atmospheric greenhouse gas (GHG) and controls numerous chemical reactions in the troposphere and stratosphere. However, there is much that is unknown about CH 4 sources and sinks and their evolution over time. Here we show that near-surface cavities in the uppermost vadose zone are now actively removing atmospheric CH 4 . Through seasonal geochemical tracing of air in the atmosphere, soil and underground at diverse geographic and climatic locations in Spain, our results show that complete consumption of CH 4 is favoured in the subsurface atmosphere under near vapour-saturation conditions and without significant intervention of methanotrophic bacteria. Overall, our results indicate that subterranean atmospheres may be acting as sinks for atmospheric CH 4 on a daily scale. However, this terrestrial sink has not yet been considered in CH 4 budget balances. M ethane (CH 4 ) is currently the most abundant non-CO 2 greenhouse gas (GHG) in the atmosphere, reaching a global average concentration of B1,800 p.p.b. at midnorthern latitudes 1 . Despite significant research progress in recent years, large uncertainties remain about the CH 4 budget and its evolution over time because there is a lack of knowledge about CH 4 sinks and sources [2][3][4][5] . Superimposed on the long-term trend of increasing atmospheric CH 4 , there is significant interannual variability 1,6,7 , and the sources of variation remain controversial 8 .Current CH 4 estimates account for B22% of the total forcing potential of all long-lived GHGs 9 . By weight, CH 4 is 28 times more effective at trapping heat in the atmosphere than CO 2 over a 100-year period 10 . Sensible mitigation strategies also require a quantitative understanding of the CH 4 budget regarding emissions and sinks 11 . The total global emissions of CH 4 are constrained reasonably well by atmospheric observations and estimates of its lifetime, based on multiple atmospheric CH 4 inversion models (top-down studies). However, the uncertainties concerning emissions/consumption from individual sources/ sinks 12 are greater, and they are poorly constrained by the current atmospheric observation network 6 . Some unaccounted sinks (or sources) could contribute the global CH 4 budget and its long-term variations.The Earth's surface exerts its influence on the free atmosphere through the atmospheric boundary layer. This lowest portion of the atmosphere ranges from a few tens of metres to 1-2-km deep 13 . The subsurface atmosphere is usually overlooked as an important part of this boundary layer. At the top of the subsurface layer in the vadose zone (below the subsoil and above the groundwater table) highly specific biogeochemical processes occur, which may act as regulators of gas exchanges between the surface and the free atmosphere.The uppermost part of the vadose zone may contain large amounts of underground air, that is, a CO 2 -rich air reservoir permeating the unsaturated...

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Section: Discussionmentioning

confidence: 99%

Subterranean atmospheres may act as daily methane sinks

et al. 2015

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“…Enhanced particle formation at locations where the ambient ionization rate exceeds ∼10 ion-pairs cm 3 s −1 . Indeed, some measurements indicate that ionization rates near the surface can exceed 100 ion-pairs cm 3 s −1 due to the accumulation of radon gas in the nocturnal boundary layer (Dhanorkar and Kamra, 1994). Recently, Vartiainen et al (2007) detected exceptionally high ion production rates of up to 30 ion-pairs cm −3 s −1 during some measurement periods.…”

Section: Simulations and Comparisons With Observationsmentioning

confidence: 99%

Ion-mediated nucleation as an important global source of tropospheric aerosols

et al. 2008

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Abstract. Aerosol nucleation events have been observed at a variety of locations worldwide, and may have significant climatic and health implications. While ions have long been suggested as favorable nucleation embryos, their significance as a global source of particles has remained uncertain. Here, an ion-mediated nucleation (IMN) mechanism, which incorporates new thermodynamic data and physical algorithms, has been integrated into a global chemical transport model (GEOS-Chem) to study ion-mediated particle formation in the global troposphere. The simulated annual mean results have been compared to a comprehensive set of data relevant to particle nucleation around the globe. We show that predicted annual spatial patterns of particle formation agree reasonably well with land-, ship-, and aircraft-based observations. Our simulations show that, globally, IMN in the boundary layer is largely confined to two broad latitude belts: one in the northern hemisphere (∼20 • N-70 • N), and one in the southern hemisphere (∼30 • S-90 • S). In the middle latitude boundary layer over continents, the annual mean IMN rates are generally above 10 4 cm −3 day −1 , with some hot spots reaching 10 5 cm −3 day −1 . The zonally-averaged vertical distribution of IMN rates indicates that IMN is significant in the tropical upper troposphere, the entire middle latitude troposphere, and over Antarctica. Comparing the relative strengths of particle sources due to IMN and due to primary particle emissions demonstrates that IMN is significant on a global scale. Further research is needed to reduce modeling uncertainties and to understand the ultimate contribution of freshly nucleated particles to the abundance of cloud condensation nuclei.

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“…Ionization rates have recently been measured by (Dhanorkar and Kamra, 1994;Wilkening, 1985;Mochizuki et al, 1977;Hensen and van der Hage, 1994). Dhanorkar and Kamra (1994) have used a set of integral ion counters to measure the small ion concentration and the aerosol ion mobility distribution at a height of about 1 m above the ground at Pune, India.…”

Section: Introductionmentioning

confidence: 99%

“…Dhanorkar and Kamra (1994) have used a set of integral ion counters to measure the small ion concentration and the aerosol ion mobility distribution at a height of about 1 m above the ground at Pune, India. The ionization rate was calculated based on a balance equation.…”

Section: Introductionmentioning

confidence: 99%

Ion production rate in a boreal forest based on ion, particle and radiation measurements

et al. 2004

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Abstract. In this study the ion production rates in a boreal forest were studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produced reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 ion pairs cm −3 s −1 , and based on external radiation and radon measurements, 4.5 ion pairs cm −3 s −1 . The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3 nm, so the sink of small ions during the nucleation events was underestimated. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. Another reason for the discrepancy is the nucleation mechanism itself. If the ions are somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days.

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Diurnal variation of ionization rate close to ground

Cited by 21 publications

References 12 publications

Subterranean atmospheres may act as daily methane sinks

Subterranean atmospheres may act as daily methane sinks

Ion-mediated nucleation as an important global source of tropospheric aerosols

Ion production rate in a boreal forest based on ion, particle and radiation measurements

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