ISSN:0148-0227    

DOI:10.1029/JD090iD04p05875

年代:1985

数据来源: WILEY

摘要:

Balloon‐borne measurements of atmospheric electrical parameters made during the last several years indicate that there has been a significant change in the average small‐ion mobility. In addition, on some soundings abrupt changes in the ion mobility profile have been noted. These variations provide an unusual opportunity to experimentally study the functional relationships between mobility, ion density, conductivity, and the recombination coefficient in the stratosphere. Within the uncertainties involved it is found that the measurements support the simple, predicted theoretical relationships between these various parameters. If fluctuations in ion mobility are in fact a usual occurrence, then this work indicates that variations frequently observed in the ion concentration are probably related to changes in ion mobility rather than aerosol variations, as is usually assumed. One somewhat surprising result predicted by the functional relationships between the electrical parameters indicates that the ambient conductivity may be relatively insensitive to mobility variati

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05876

年代:1985

数据来源: WILEY

摘要:

The investigation of ion chemistry and the properties of ions and cluster ions is essential for a fundamental understanding of factors that affect atmospheric electrical conductivity. Recent mass spectrometeric observations of ambient stratospheric and tropospheric ions and recent laboratory studies of these ions are reviewed, and our present knowledge of the chemical nature of ions below 50 km is assessed. Some organic species, namely, trimethylamine, pyridine, and methylpyridines, are suggested to participate in the tropospheric positive ion chemistry.

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05885

年代:1985

数据来源: WILEY

摘要:

Ion spectra obtained during three balloon flights performed in June 1982, September 1982, and September 1983 are reported. The lower altitude limit of the measurements is imposed by the decrease of the instrument sensitivity and the upper limit by present ballooning techniques. At high altitudes the ion spectra are disturbed by contamination, whereas at low altitudes, ion cluster breakup is a severe problem. Nevertheless knowledge of relative abundances of the different negative ion mass peaks, mainly belonging to the NO3−(HNO3)nand HSO4−(HNO3)m(H2SO4)tcluster families allows the derivation of concentrations of H2SO4in the altitude region of 22–45 km. At 45 km an increased SO2mixing ratio, possibly due to volcanic activities, was estimated from the negative ion mass spectra. The data are discussed in terms of previous measurements and models. Special interest is given to the sulfur chemistry and the implications on aerosol form

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05891

年代:1985

数据来源: WILEY

摘要:

A method has been developed and used to obtain theoretical predictions of the electric conductivity measured by an electrostatic probe in an atmospheric ionized gas, i.e., with mean free path very much less than probe radius. Three different methods for conductivity measurements have been analyzed: (1) attracting potential method; (2) transient response method; (3) space potential method.

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05897

年代:1985

数据来源: WILEY

摘要:

Natural diffusive deposition of radon daughter products from the atmosphere onto an aerodynamically rough, vegetated surface may cause an important enhancement of the ionization rate within the plant canopy. For example, the blades of grass in a lawn may become slightly radioactive, leading to higher ionization in the air between them than above their tops. The impact of this increased ionization rate is estimated from a simple model of the conductivity profile in the turbulent “electrode layer”. It is found that an order‐of‐magnitude augmentation can have substantial effects on the electrical structure. With this motivation a one‐dimensional, steady state model of radon daughter, dry deposition is developed for estimating the magnitude of the deposited activity. The effects of aerosol attachment and of the entire decay chain are included. This model predicts significant enhancements of the “surface radioactivity” under typical continent

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05901

年代:1985

数据来源: WILEY

摘要:

The contribution of radioisotopes of continental surface origin to the production of ions in convective storms has not been adequately assessed. The average222Rn flux from bare soils and average distributions of222Rn versus altitude in the troposphere for the normal range of vertical eddy mixing rates provide an inadequate basis for such an assessment. The influence of the biosphere, particularly the substantially higher fluxes for transpired222Rn and220Rn, and enhanced ion production by high concentrations of222Rn and220Rn decay products on aerosols and vegetation surfaces, have not been considered. Effective transpiration of222Rn and220Rn by vegetation is due to their high concentrations in soil gas and their solubility in soil moisture. Substantially enhanced fluxes of222Rn over a mature corn field (6 times higher than the average flux over bare soils), and of220Rn over a wheat field, illustrate the effectiveness of plant transpiration. Conditions favoring effective transpiration include mature vegetation, excess soil moisture throughout the root zone, strong radiative heating of the leaf canopy, and moderate surface winds. Rising air parcels with transpired water vapor,222Rn,220Rn, and their decay products may contribute importantly to the development of cumulus clouds and air mass storms. The dynamic lift of surface air, which feeds updrafts of convective storms, transports radioisotopes and ions from several sources within the vegetation canopy: transpired222Rn,220Rn, and their decay products; ions produced by the decay products of220Rn and222Rn on aerosol and vegetation surfaces; and biological aerosols and plant debris with high surface concentrations of radioisotopes. Observed frequencies of lightning flashes are highly correlated with areas of effective transpiration and their variations with season, latitude, and time of day.

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05909

年代:1985

数据来源: WILEY

摘要:

Calculations of the ion‐aerosol attachment coefficients are carried out for particles with radii between 0.001 and 4 μm in a bipolar ion environment by using the theory (Hoppel, 1977) that includes both image capture and three‐body trapping of ions. These attachment coefficients are used to calculate the equilibrium charge distribution on aerosols. The results are compared to Fuchs' theory and to several recent measurements of the equilibrium charge distribution. The experimentally measured charge distributions agree quite well with theory. Recent measurements of aerosol size distributions made with the differential mobility size spectrometer in both continental and oceanic atmospheres are used together with the calculated attachment coefficients to study the sensitivity of the atmospheric ion concentration on the aerosol size distribu

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05917

年代:1985

数据来源: WILEY

摘要:

Electrical conductivity measurements of ocean air have been made since 1907, and since the electrical conductivity depends on the aerosol concentration in the air, these measurements constitute the longest running record of the aerosol concentration of marine air. The conductivity measurements in the northern hemisphere show an apparent decrease with time, while those in the southern hemisphere are reasonably constant. The apparent increase in aerosol concentration with time in the northern hemisphere, implied by the decrease in conductivity, has been taken by earlier authors to be caused by pollution from the increased industrial development in the northern hemisphere. Ellsaesser (1975), however, pointed out that this interpretation is not consistent with other indications of pollution trends. In this paper an examination is made of the possibility that the apparent increase in aerosol concentration in the northern hemisphere may be due to the increase in the number of moderate‐sized volcanic eruptions in the northern hemisphere that have been reported during the past half century. In this paper the historical record of volcanic activity and conductivity measurements is examined. It is found that decreases in conductivity and the corresponding increases in aerosol concentration appear to occur within a few months following moderately large volcanic eruptions. The more numerous moderate‐sized eruptions appear to have a greater effect than the relatively few very large eruptions. The good correlation between known volcanic eruptions and the decreases in conductivity suggests that the decreases in fair‐weather marine conductivity during this century is indicative of an increase in volcanic activity. Thus the suggestion of Newhall and Self (1982) that the increases in volcanic activity may be only apparent because of better reporting is not fully conclusive. While it is true that the reporting has improved over the past 70 years, our results support the assumption that there has also been a de facto increase in such volcanic act

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05925

年代:1985

数据来源: WILEY

摘要:

Properties of atmospheric small ions are studied in different environments including a valley in a semiarid region of the southwestern United States, a nearby mountain top, and a cave where the radon concentration and the absolute humidity are quite high and the condensation nuclei concentration is low. Owing to a high ion pair production rate from the radon and low condensation nuclei content, the electrical conductivity and the small ion densities in the cave air exceed those of the free atmosphere by 2 and 3 orders of magnitude, respectively. The relatively high water vapor and carbon dioxide levels coupled with a low aerosol concentration in the cave appear to favor the growth of ion complexes having lower mobilities than ordinary atmospheric small ions. Atmospheric electrical parameters on the mountain differ by small amounts in comparison with the valley. Atmospheric variables at the mountain site hinge largely on the summer thunderstorm season that set it off from the semiarid setting of the valley location.

ISSN:0148-0227    

DOI:10.1029/JD090iD04p05933

年代:1985

数据来源: WILEY