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1.
Stellar ultraviolet light near 2500 Å is attenuated in the Earth's upper atmosphere due to strong absorption in the Hartley continuum of ozone. The intensity of stars in the Hartley continuum region has been monitored by the University of Wisconsin stellar photometers aboard the OAO-2 satellite during occultation of the star by the Earth's atmosphere. These data have been used to determine the ozone number density profile at the occultation tangent point. The results of approximately 12 stellar occultations, obtained in low latitudes, are presented, giving the nighttime vertical number density profile of ozone in the 60- to 100-km region. The nighttime ozone number density has a bulge in its vertical profile with a peak of 1 to 2×108 cm?3 at approximately 83 km and a minimum near 75 km. The shape of the bulge in the ozone number density profile shows considerable variability with no apparent seasonal or solar cycle change. The ozone profiles obtained during a geomagnetic storm showed little variation at low latitudes.  相似文献   

2.
The Stratospheric Aerosol and Gas Experiments (SAGE) I and II measure Mie, Rayleigh, and gaseous extinction profiles using the solar occultation technique. These global measurements yield ozone profiles with a vertical resolution of 1 km which have been routinely obtained for the periods from February 1979 to November 1981 (SAGE I) and October 1984 to the present (SAGE II). The long-term periodic behavior of the measured ozone is presented as well as case studies of the observed short-term spatial and temporal variability.

A linear regression shows annual, semi-annual, and quasi-biennial oscillation (QBO) features at various altitudes and latitudes which, in general, agree with past work. Also, ozone, aerosol, and water vapor data are described for the Antarctic springtime showing large variation relative to the vortex. Cross-sections in latitude and altitude and polar plots at various altitudes clearly delineate the ozone hole vertically and areally. Comparisons of vertical profiles are made from 1979 to 1988.

Although there is a three-year gap between the SAGE I and II measurements, the two data sets have been used to determine long-term changes in ozone. The intercomparison generally shows decreases in the upper stratosphere (25–50 km) of 4% or less from 1980 to 1986.  相似文献   


3.
Temporal variations of the Martian ozone density profile at high latitudes have been calculated for an entire Martian year, taking into account the seasonal and diurnal variations in temperature, water vapor and solar radiation. A new technique facilitates the long-term model calculations, including diurnal variations. The result is in better agreement with MARINER 9 observations of the time and magnitude of the seasonal maximum than is the result of the previous seasonal model calculated for the diurnally averaged temperature, water vapor and solar radiation. The large scatter of the MARINER 9 data may be partly experimental, but the effect of surface condition, including the water vapor variability and the surface chemistry, may explain some of the dispersion of the observed data. The predicted diurnal variation is substantial except near solstices, and the nighttime total column density is generally larger than the daytime value. The magnitude of the day-and-night difference and the shape of the diurnal variation change markedly with season. The opposite temporal variation is predicted for ozone density between the upper and lower regions. The model predicts the production of a ozone layer at 35–50 km, which is consistent with observations at low latitudes by MARS-5. The observed ozone density may be explained, if the atmospheric temperature is as low as ～ 140 K or if the atmosphere is subsaturated. Effects of the simultaneous existence of an aerosol layer, also observed by MARS-5, are briefly discussed.  相似文献   

4.
Ozone is a tracer of photochemistry in the atmosphere of Mars and an observable used to test predictions of photochemical models. We present a comparison of retrieved ozone abundances on Mars using ground-based infrared heterodyne measurements by NASA Goddard Space Flight Center’s Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) and space-based Mars Express Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) ultraviolet measurements. Ozone retrievals from simultaneous measurements in February 2008 were very consistent (0.8 μm-atm), as were measurements made close in time (ranging from <1 to >8 μm-atm) during this period and during opportunities in October 2006 and February 2007. The consistency of retrievals from the two different observational techniques supports combining the measurements for testing photochemistry-coupled general circulation models and for investigating variability over the long-term between spacecraft missions. Quantitative comparison with ground-based measurements by NASA/GSFC’s Infrared Heterodyne Spectrometer (IRHS) in 1993 reveals 2-4 times more ozone at low latitudes than in 2008 at the same season, and such variability was not evident over the shorter period of the Mars Express mission. This variability may be due to cloud activity.  相似文献   

5.
Ozone profiles on a global scale can be derived from GOME satellite data by minimizing the difference between the measured and the corresponding simulated spectra as a function of the vertical distribution of 03. For this purpose the FUll Retrieval Method (FURM) was developed, which is based on the optimal estimation approach and contains the radiative transfer code GOMETRAN as an essential component. The quality of the GOME ozone profiles is assessed by comparing them with 197 coincident ozonesonde measurements at five selected European stations. The comparison results show that the seasonal ozone variations are very well reproduced by the GOME profiles. The agreement between the GOME and the sonde measurements is best above 18 km altitude where the mean relative difference is below 10% and the root mean square of the relative differences is of the order of 10%. Larger differences occur in the tropopause region and lowermost stratosphere where the natural ozone variability is largest.  相似文献   

6.
Fluorescent emissions from nitric oxide appear imposed upon the Rayleigh backscattered spectrum of the earth's atmosphere between 250 and 300 nm in wavelength. Satellite instruments designed to monitor the global ozone distribution can routinely observe these signals although techniques for exploiting the data are not yet available. Application of a radiative transfer equation developed for an atmosphere including absorption by ozone, molecular scattering, and nitric oxide fluorescence shows the three most prominent NO emissions relative to the 250–300 nm backscattered sunlight to be the (1,4), (1,6), and (0,3) gamma bands. Analysis of the contribution function for each emission band indicates that the fluorescent signals can provide useful information on the magnitude and variability of nitric oxide between 40 and 140 km in altitude.  相似文献   

7.
A 3-D Atmospheric Chemical Transport model has been developed and used to simulate the present-day ozone distributions in the troposphere and stratosphere. A 5-year-long steady-state model run using 1995 boundary conditions and circulation fields derived from the 24-layer University of Illinois at Urban a-Champaign (UIUC) Atmospheric General Circulation model has been carried out. The simulated distribution of ozone is compared with available observations made by the HALOE, CLAES and MLS instruments onboard the LIARS satellite. The comparison is carried out for the monthly zonal-mean climatology of the ozone distribution. The correlations between the monthly zonal-mean ozone derived from the simulated and measured data are calculated. The results of this comparison show reasonable agreement (within 30%) of the simulated and measured monthly zonal-mean ozone distributions, although the location of the simulated maximum in the ozone distribution is generally lower by about 2–3 km than shown by the satellite data. The model overestimates the ozone mixing ratio in the lower stratosphere and slightly underestimates it in the upper stratosphere. A better overall agreement was found between the simulated ozone and the ozone measured by HALOE than by CLAES and MLS.  相似文献   

8.
The Dobson ozone spectrometer has been used for studies of the ozone layer for about 60 years. It remains indispensable for assessing the accuracy of satellite-borne instruments. The steps which led to the present understanding of global ozone distribution and variations are reviewed.  相似文献   

9.
Total atmospheric ozone has been measured at the “Observatoire de Haute-Provence”, Chiran Station, 1905 m high with a ground based, high resolution i.r. spectrometer, using the Sun as a source. Results are compared with a Dobson spectrophotometer which has been calibrated and intercompared with a standard. Total ozone values found with Dobson are 4% lower than values given by i.r. measurements. In addition, a negative correlation between total ozone and tropopause height has been found.  相似文献   

10.
The fluctuation and the periodicities of the total ozone layer for the period 1957–1990 is studied. Monthly total ozone data from 32 ground based stations have been analysed. It is shown that the maxima and the minima of the monthly values of total ozone for each year and for the whole period in question do not necessarily occur in March or in April and in September or October but range from March till July and from September till December respectively. Periodicities of 3, 4 and 6 months have been revealed. Finally the maxima and the minima of the total ozone data were examined. The variation of the whole phenomenon is analytically expressed with the help of an algebraic formula and can represent the observed monthly ozone values with an accuracy of 97%.  相似文献   

11.
The Nimbus 7 Total Ozone Mapping Spectrometer data over Europe have been specially processed for the 2 days of the ozone sensor intercomparison balloon campaign in June 1981 at Gap, France. The 19 June TOMS map shows an elongated ozone maximum (~ 400 D.U.)extending in a NW-SE direction across central Europe and an ozone minimum (300 D.U.) in the central Atlantic. This pattern produces a 12 D.U. decrease along the balloon trajectory from the first ascent to the second descent. On 26 June a much smaller ozone maximum (400 D.U.) is centered in northern France with its main axis running in a SW-NE direction. The total ozone contours tend to lie parallel to the balloon trajectory so that the total ozone during the flight is nearly constant.  相似文献   

12.
Mars Express observations give ozone abundances that are smaller than those from the ground-based infrared heterodyne and HST observations at low and middle latitudes. Both ground-based and Mars Express observations of the O2 dayglow at 1.27 μm, which originates from photolysis of ozone, are in mutual agreement after correction for the local time variability. Therefore a problem appears: whether the MEX ozone data are compatible with (1) the observed O2 dayglow intensities and (2) the photochemical model by Krasnopolsky [Krasnopolsky, V.A., 2006. Icarus 185, 153-170] within uncertainties of its reaction rate coefficients. That model involves heterogeneous loss of H2O2 on water ice and agrees with the observations of the O2 dayglow, H2O2, and the ground-based and HST ozone. The answers are ‘yes’ to both questions. A version of the model is given that fits the MEX ozone as well as the observed O2 dayglow and H2O2. Laboratory studies of two reaction rate coefficients could indicate a preferable version of the model and a preferable set of the ozone data (MEX versus the ground-based and HST). The predicted seasonal behavior of H2O2 is different from that in the model by Lefevre et al. [Lefevre, F., Bertaux, J.L., Clancy, R.T., Encrenaz, T., Fast, K., Forget, F., Lebonnois, S., Montmessin, F., Perrier, S., 2008. Nature 454, 971-975], and future observations may help to choose between the models.  相似文献   

13.
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14.
Interdisciplinary studies, combining the evaluation of ozone effects with the meso-meteorological interpretation of the ozone data have been carried out in eastern Spain since 1994. Mesoscale circulations are very important from the point of view of how and where forest ecosystems are affected by point sources and regional air pollution in the Mediterranean Area. First results of these field surveys show that during 1994, 95 and 96, ozone visual injury (chlorotic mottle) in Pinus halepensis Mill. was well correlated with the penetration of the sea breeze in coastal valleys of Castellón. Patterns of ozone injury, chlorotic mottle, have been positively correlated with needle-age classes looking at tree level.  相似文献   

15.
The examination of the role of the lower stratospheric circulation to the vertical ozone distribution, is attempted by using the vertical ozone profiles collected by balloon-borne sondes released at Athens, Greece (38°N, 24°E), throughout the period 1989–1997. The most pronounced special features of the ozone structure, such as lamination phenomenon, minimum of ozone partial pressure at the height region of 14–17 km and ozone minima at the height region of 20–25 km, have been used in order to create groups of relevant profiles. The occurrence of the above mentioned features, correlated with the circulation pattern, leads to the following preliminary results: a) Laminated features are associated with the north-northwest circulation in the lower stratosphere; b) The lower stratosphere's characteristic ozone minimum is related to the influence of the subtropical jet stream circulation; and c) The observed ozone depletion at the height region of 20–25 km, is characterized by the movement of the polar vortex to the mid-latitudes, resulting more intense north-western circulation above our experimental site.  相似文献   

16.
Stellar occultation data from the 2460 Å and 2980 Å channels of the OAO-2 stellar photometers have been used to derive the nighttime ozone number density distribution in the low latitude mesosphere. The nighttime ozone distribution obtained from both channels are similar indicating a maximum in the ozone distribution near 80km of 2–3 × 103cm?3.  相似文献   

17.
The ozone height profile in the Arctic, at the end of the winter, has been measured up to an altitude of 100 km using a combined solar occultation and 1.27 μ oxygen emission technique. The typical two layer structure has been observed with a high altitude minimum near 80 km and a maximum at 86 km. The measured concentration in this ozone bulge was 5.1 × 107cm?3, typical of that measured at 52°N for the summer months. It is suggested that this reduced ozone concentration may have been associated with a stratospheric warming event that was in progress at the time of the measurement.  相似文献   

18.
Atmospheric ozone number densities have been determined over the altitude range 30–75 km by measuring the absorption of lunar u.v. radiation in a number of wavelength bands between 2400 Å and 2900 Å. The measurements were made from rockets fired at night at times close to full Moon and show significant variations in ozone densities particularly at the higher altitudes. Comparison with other observations indicates that above 60 km the ozone densities at night are markedly greater than they are during the day.  相似文献   

19.
A two-dimensional model of radiative, dynamical and photochemical processes in the atmosphere has been developed and used for the simulation of ozone distribution. The results of numerical simulations are compared with LIARS and TOMS measurements. The comparison shows that the overall agreement between simulated and LIARS stratospheric ozone data is within 5–15% for almost all of the stratosphere except for the high latitudes of the winter hemisphere. This kind of disagreement is a common problem for all 2-D models, which cannot resonably reproduce planetary and gravity wave breaking processes over high latitudes. Validation of the simulated total ozone against TOMS data also shows a good overall agreement. The the total ozone difference between the 2-D model results and TOMS measurements is within 5–10% in both Northern and Southern hemispheres during all seasons except 40°S-60°S from June to October. In this region, the difference between simulated and TOMS total ozone is 30%.  相似文献   

20.
A critical study of distribution of ozone with altitude of about 91 Km and above has been made and following important results are obtained:(i) An empirical equation is fitted theoretically between the variation of ozone concentration and altitude at a definite time.(ii) The rate of change of O3 concentration with respect to altitude is directly proportional to the O3 concentration at that altitude.(iii) From analysis it is shown that ozone concentration decreases with the increase of altitude.  相似文献   

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