Ion Composition and Electron-and Ion-Loss Processes in the Earth’s Atmosphere

Persistent ice cloud in the midsummer upper mesosphere at high latitudes: Three‐dimensional modeling and cloud interactions with ambient water vapor

“…The absolute densities and profiles of a number of specific ions are predicted to depend significantly on the ambient water vapor pressure. Measurements of water cluster ions [ Swider and Narcisi , 1975; Arnold and Krankowsky , 1977; Kopp , 1984, 1990] and of silicon ions [ Solomon et al , 1982] using rocketborne mass spectrometers combined with models of the ion chemistry [e.g., Reid , 1989] have yielded a number of times sub‐ppm mixing ratios of water vapor. Yet from the published literature we do not see a consistent picture emerging that these sub‐ppm values are typical for the midsummer high‐latitude mesopause region.…”

A study of the enhanced electron concentrations in the mid-latitude D region on winter days in terms of the positive-ion chemistry.

“…For the winter results, P80, P83, and P84 refer to weak radio-wave absorption conditions, and P82, P179, and S43 to strong absorption conditions. Coordinated measurements of positive-ion composition near the time of measurement P179 showed that NO was by far the dominant ion species over the height range 72-115km ARNOLD and KRANKOWSKY, 1977). This was in marked contrast to the normal situation in which 02-ion concentrations are comparable with those of N0+ above about 83 km, water cluster ions being dominant at lower heights.…”

“…The continuous and broken lines correspond to the atmospheric temperature variations represented by the continuous and broken lines, respectively, in Fig. 2. of collisional dissociation of N0+C02 in determining the ratio of N0+ to more rapidly recombining ions, and thereby the electron concentration 6.2 Ion-composition changes during winter anomaly conditions One feature of the ion-composition measurements during winter anomaly conditions, which is particularly striking in the results for SUist (ARNOLD and KRANKOWSKY, 1977), is the small ratio of 02+ to N0+ concentrations at mesospheric heights, compared with normal conditions This is consistent with the changes considered in this paper, particularly the increases in NO concentrations, and is inconsistent with mechanisms involving increased 02+ production, either by particle precipitation or by photoionization of enhanced 02(145) concentrations A more noticeable feature of all ion-compositon measurements during anomalous winter conditions (ZBINDEN et al, 1975;AIKIN et al, 1977;ARNOLD and KRANKOWSKY, 1977) is the reduction in the transition height between N0+ and water cluster ionsAt Arenosillo, Spain, and Salto di Quirra, Sardinia, ZBINDEN et al(1975) and ARNOLD and KRANKOWSKY (1977), respectively, found this transition height to be near 76km and 74km, whereas at SUist the latter authors reported the height to be near 71km, in the observation carried out in association with that of the electron density distribution P179 An increase in temperature also results in a lowering of the transition height but with the form of the increased temperatures shown in Fig2 no effect could be expected below 75kmCalculations with the temperature increase to 281 K extended down to 70km showed a transition height near 72km for the B distribution of nitric oxide, Fig2However, the electron concentration calculated for 75km was only one-half that of that shown in the P179 distribution, Fig, 1, and a four-fold increase in nitric oxide concentration above the values of the B distribution would be required to remove this discrepancy As already noted in studies by THOMAS (1976a, b) and REID (1977), the current model of the D-region positive ion-chemistry predicts substantial concentrations of N0+ hydrates; this is illustrated in Fig7The mass-spectrometer measurements of ZBINDEN et al(1975), AIKIN et al(1977), andKRANKOWSKY (1977) all show evidence of NO H20 but in relatively low concentrationsIf as Reid has suggested, these hydrates are dissociated during the mass-spectrometer sampling and recorded as NO, the relevant transition heights to be considered in the calculations would be those between total cluster ions and the sum of NO and its hydrates It is seen from Fig7 that this occurs at about 77km and 74km for the Meira and B profiles for nitric oxide, respectively. However, it is found that the corresponding results for nitric oxide concentrations larger by a factor of ten than those of B distribution at lower heights show a transition height near 71km, as observed.…”

The lower ionosphere: Abandoned by communication, to be re-discovered for aeronomy

“…Another good example, demonstrating the impact that the nature of the positive ions has on the concentration of electrons, is given in Figure 4. The partial ion densities ofa rocket-borne mass spectrometer showed that molecular ions dominated above 77.3 km, whereas below that height, the positive species were mainly cluster ions of the type NO+ (H 2 0)n and H+ (H 2 0)n' which have significantly larger recombination rates (3]. In the right panel, the effective recombinationrate, ljf = qj N; ,isplottedfrom data obtained by the same rocket [4].…”