摘要:

By means of calculations with a one‐dimensional photochemical‐diffusive model of the atmosphere a theoretical estimate is given of the present and the possible future impact of large sections of the chlorocarbon industry on the ozone layer. Our estimates for 1976 are that past chlorocarbon emissions may be responsible for a 1.5% reduction in the global total ozone content (0.8% by CFCl3and CF2Cl2, 0.5% by CCl4, and 0.2% by CH3CCl3). This estimate was obtained by comparison with the ozone content of a model atmosphere without industrial chlorocarbon emissions. The effect of the nonindustrial gas CH3Cl can best be described by stating that without CH3Cl, there would be almost 1% more ozone in the atmosphere. Considerable attention should also be given to the atmospheric effects of expanding uses of CH3CCl3. The potential impact on the ozone layer of CHFCl2and CHF2Cl emissions is also discussed. However, there are too many uncertainties regarding the tropospheric concentrations of OH and its role as a scavenger to assess the effect of a number of chlorocarbon compounds reliably. The effect of other chlorocarbon compounds (C2Cl4, C2HCl3, C2H5Cl, C2H4Cl2, CHCl3) on the ozone layer is estimated as being comparatively negligible. Model‐calculated vertical distributions of a large number of constituents are compared with observations. Substantial deviations between some theoretical and reported concentrations exist, especially for NOx, CO, and ClO. Uncertainties in our knowledge of stratospheric chemistry are discussed. It is concluded that these uncertainties are sufficiently numerous to take the given predictions of ozone reductions with some reserva

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00345

年代:1978

数据来源: WILEY

摘要:

Global calculations of stratospheric HOx, Clx, and NOxare presented which include the effects of planetary albedo and diurnal and seasonal variations of the insolation. Comparisons are made with a wide range of atmospheric measurements at different latitudes and altitudes. Agreement between theory and observations is generally within a factor of 2. The theory appears to explain adequately the major features of latitude and seasonal distributions of NO2and HNO3. The results indicate that mesospheric OH makes an appreciable contribution to the total OH column abundance and strongly suggest that nitrogen oxides exist principally in the form of HNO3at high latitudes in winter. There are difficulties in reconciling OH, ClO, and O3observations in the upper stratosphere.

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00364

年代:1978

数据来源: WILEY

摘要:

Data from surface‐based Umkehr and satellite ultraviolet backscatter observations of the vertical distribution of ozone in the upper stratosphere are compared. The satellite data are limited to four single‐pass observations of the vertical‐meridional distribution of ozone at different seasons of the year during 1970. The Umkehr data are climatological means over several years of observations. Although most of the observations made with the surface and satellite systems do not coincide in time, they nevertheless show a general agreement in seasonal variations that clearly appear in the more complete set of Umkehr data. Average values of ozone concentrations for satellite and Umkehr observations and a standard ozone profile are intercompared and show some significant differ

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00379

年代:1978

数据来源: WILEY

摘要:

Electric fields produced by air mass thunderstorms have been recorded at 25 field mill sites at the NASA Kennedy Space Center (KSC) during the summers of 1975 and 1976. Time‐ and area‐averaged fields produced by individual storms are typically −0.8 to −2.1 kV m−1during periods of intense lightning activity and usually 2–4 times larger (−2.3 to −4.3 kV m−1) in the final, less active storm periods. The total number of lightning discharges generated by individual storms ranged from 8 to 1987. The average flashing rate per storm was 0.3–9.3 discharges per minute. Large storms tend to evolve through an initial, an active, and a final phase of electrical activity. The average point discharge computed during the active period is 3–4 times less than that computed during the final phase. In 1975, about 71% of all lightning discharges occurred during active storm periods, which in turn represented only about 27% of the total storm durations. In general, the structures of the electrostatic fields produced by lightning discharges in Florida were found to be similar to those in other geographical locations. During active storm periods, 42–52% of all lightning discharges were to ground, and during a final storm period only about 20% were to ground. The fraction of discharges to ground which contained continuing currents ranged from 29 to 46%; the mean duration of 239 ground flashes was about 420 ms. The average density of lightning flashes to ground during 1974 and 1975 at KSC was about 6 km−2month−1during

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00385

年代:1978

数据来源: WILEY

摘要:

A simplified version of the turbulent electrode effect is developed for use as a charge source in a convection current model. Asymptotic analysis is applied to the conservation equations for small ions to show that the conductivity profile in the electrode layer becomes independent of the conduction process in the limit of strong turbulent mixing. In this limit, which is found to be applicable to the atmospheric surface layer under many circumstances, the electrode effect can be described simply by a charge conservation equation with an externally determined mean conductivity profile decreasing to zero at the surface.

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00402

年代:1978

数据来源: WILEY

摘要:

Fluctuating quantities of vertical wind speed, horizontal wind speed, and concentration of particles with radii between 0.5 and 3 μm were observed for dusty air generated by wind erosion of soil a short distance upwind of the sensors. Probability distributions for the fluctuating quantities showed a form that was explained by a strong correlation of particle concentration with wind speed, momentum flux downward, and particle flux downward. A distribution showing percentage of the particle flux indicated that the most effective fluctuation scales were within 1–3 standard deviations of the means. The distribution showed that much of the flux was counter to the gradient in a rather inefficient turbulent mixing process. Observations that a large contribution to total particle flux occurs at horizontal wind speeds as high as 3 standard deviations above the mean would indicate that wind tunnel tests with a distribution of horizontal wind speeds narrower than distributions of natural winds may give significantly different suspension results for wind erosion studies. The authors interpret the strong correlation of horizontal wind speed and particle concentration to show a very fast response of small particle input by ‘sandblasting’ (disaggregation of small particles from larger particles and splashing of loose small particles from the surface). This sandblasting is driven by saltation of larger sand grains, a process which is highly responsive to

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00409

年代:1978

数据来源: WILEY

摘要:

Radon (222Rn) measurements provided a simple, reliable, in situ indicator of the continental component of the resident air masses during marine fog events off Nova Scotia in August 1975. Frequent and substantial changes in the continental component of the air, including an increase from 5 pCi m−3(mostly maritime air) to 80 pCi m−3(continental air) within 6 hours on August 5 at a location 100 km off shore illustrate the variations in the nature of over‐ocean air and the importance of continuous sampling of the surroundings during shipboard atmospheric experiments. The recent 1‐ or 2‐day histories of the air for several fog events were investigated by relating the air mass movement as suggested by weather maps to the measured radon concentration. The reliability of determination of atmospheric radon concentrations by measurement of the beta radioactivity of daughter products collected on filter paper was verified as being applicab

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00415

年代:1978

数据来源: WILEY

摘要:

A number of closely spaced airborne radiometer flights over the entire Keweenaw Current in Lake Superior suggest that bathymetry plays a major role in determining the overall features of the current. The crosscurrent surface temperature variations are correlated over long‐current distances of kilometers only in a loose sense, and the crosscurrent fine structure is essentially uncorrelated over the same distance. The crosscurrent temperature variations are often dominated by very sharp fronts, which seem to become unstable and spawn meanders along their outer edg

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00419

年代:1978

数据来源: WILEY

摘要:

Phillips (1966) considered a linear, barotropic, nondivergent model driven by time‐dependent winds in an attempt to explain theAriesobservations. He found that the model greatly underestimated the response as compared to the observations. The model is reexamined by using newer estimates of the wind stress (Bunker, 1975) and of the eddy kinetic energies (Freeland et al., 1975). With these the model predicts reasonably well the time and space scales and the amplitude of the barotropic mesoscale variability south of Bermuda. It is suggested that the low‐frequency temperature fluctuations observed in thePanulirusdata near Bermuda result from the advection of the mean baroclinic field past Bermuda by the barotropic fluctuati

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00427

年代:1978

数据来源: WILEY

摘要:

Recent measurements of naturally occurring electromagnetic (em) fields on the sea floor have demonstrated a prominent spectral peak at about 0.2 Hz. The fields associated with this peak are not correlated with natural em signals measured on land adjacent to the oceanic observing station but seem to be related to ocean surface waves having a frequency one half that of the spectral peak. It is proposed that the nonlinear interaction of opposed trains of surface waves (similar to the mechanism thought to be responsible for microseisms) generating fluid motion across the geomagnetic field causes the observed signal. Calculations are presented to substantiate this proposed mechanism.

ISSN:0148-0227    

DOI:10.1029/JC083iC01p00431

年代:1978

数据来源: WILEY