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1.
Stratospheric concentrations of OH have been derived from LIMS measurements of minor constituents. Two methods have been used. Assuming that HNO3 and NO2 are in photochemical steady state, LIMS measurements of these species, with knowledge of appropriate rate constants and a calculation of the HNO3 photolysis rate, allow nearly global fields of OH to be derived. The derived profiles show satisfactory agreement with observations. As a check on our method, OH has also been derived by calculations of its sources and sinks using LIMS measurements of H2O. The two methods agree extremely well in low latitudes. At higher latitudes the agreement is less satisfactory. This is discussed in terms of the diurnal behaviour of the species and the time constant of the HNO3/NO2 equilibrium.  相似文献   

2.
The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O3, H2O, NO2, and HNO3. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO2 and HNO3, are important elements in the NOx chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred.  相似文献   

3.
Far infrared limb thermal emission spectra obtained from balloon borne measurements made as a part of the Balloon Intercomparison Campaign (BIC) have been analyzed for retrieval of stratospheric trace constituent distributions. The measurements were made with a high resolution Michelson Interferometer and covered the 15–180 cm−1 spectral range with an unapodized spectral resolution of 0.0033 cm−1. The retrieved vertical profiles of O3, H2O, HDO, HCN, CO and isotopes of O3 are presented. The results are compared with the BIC measurements for O3 and H2O made from the same balloon gondola and with other published data. A comparison of the simultaneously retrieved profiles for several gases with the published data shows good agreement and indicates the validity of the far infrared data, the retrieval techniques and the accuracy of the inferred profiles.  相似文献   

4.
The measurements of positive ion composition in the high latitude D-region have revealed an excess of 34+ under distrubed conditions which has been interpreted as H2O2+. At the same altitude range near the transition height oxonium ions were measured as well. This paper presents a new model for the production and loss of oxonium ions with their production from H2O2+ + H2O → H3O+ + HO2 and their loss by attachment of N2 and/or CO2. A reaction constant of 8.5×10?28 (300/T)4 cm6s?1 has been obtained for the three body attachment H3O+ + CO2 + M → H3O+.CO2 + M from the measured density profile of 63+ in flight 18.1020. Mesospheric H2O and H2O2 densities are inferred from measurements of four high latitude ion compositions based on the oxonium model. The mixing ratios of hydrogen peroxide are up to two orders of magnitude higher compared to previous model calculations. In order to explain the missing production of odd hydrogen, we consider larger O(1D) densities, surface reactions of O(3P) on particles, and cathalytic photodissociation of water vapor on aerosol particles.  相似文献   

5.
The purpose of the Nimbus 7 LIMS experiment was to sound the composition and structure of the upper atmosphere and provide data for study of photochemistry, radiation, and dynamics processes. Vertical profiles were measured of temperature and ozone (O3) over the 10-km to 65-km range and water vapor (H2O), nitrogen dioxide (NO2), and nitric acid (HNO3) over the 10-km to ~50-km range. Latitude coverage extended from 64°S to 84°N. Several general features of the atmosphere have emerged from data analyses thus far. Nitrogen dioxide exhibits rapid latitudinal variations in winter and shows hemispheric asymmetry with generally higher vertical column amount in the summer hemisphere. HNO3 data show that this gas is highly variable with altitude, latitude, and season. Smallest mixing ratios occur in the tropics, and the largest values occur in the high latitude winter hemisphere. The results show that O3, NO2, and HNO3 are strongly affected during a stratospheric warming. There is a persistently low water vapor mixing ratio in the tropical lower stratosphere (~2–3 ppmv), a poleward gradient at all times in the mission, and evidence of increasing mixing ratio with altitude at tropical and middle latitudes.  相似文献   

6.
During the last few years a gas expansion system, combined with a mass spectrometer has been developed and successfully flown in the stratosphere. Neutral gas particles are formed into a molecular beam which traverses the ion source of the mass spectrometer without wall interactions. Vertical profiles of constituents such as H2O, CO2 and O3 have been measured in the altitude range of 20 to 40 km during balloon descents. Isotopes of major atmospheric gases (N2, O2, Ar) provided in-flight calibration standards.Before each flight the mass spectrometer system was calibrated in the laboratory for many gases of interest, including ozone. Mixing ratios of ozone determined from recent flights have accuracies of better than 5%. The sensitivity of the system was sufficiently high to detect, in addition, the heavy isotope of ozone at mass 50. A pronounced enhancement of heavy ozone in the upper stratosphere has been found. The mass spectrometer system provides the unique opportunity to perform in the stratospherein-situ measurements combined with isotopic studies.  相似文献   

7.
The Ultraviolet Coronagraph Spectrometer on the Solar and Heliospheric Observatory, UVCS/SOHO, and the Ultraviolet Coronal Spectrometer on the Spartan 201 satellite, UVCS/Spartan, have been used to measure H I 1215.67 Å line profiles in polar coronal holes of the Sun at projected heliocentric heights between 1.5 and 3.0 R. UVCS/SOHO also measured line profiles for H I 1025.72 Å, O VI 1032/1037 Å, and Mg X 625 Å. The reported UVCS/SOHO observations were made between 5 April and 21 June 1996 and the UVCS/Spartan observations were made between 11 and 12 April 1993. Both sets of measurements indicate that a significant fraction of the protons along the line of sight in coronal holes have velocities larger than those for a Maxwellian velocity distribution at the expected electron temperature. Most probable speeds for O5+ velocity distributions along the lines of sight are smaller than those of H0 at 1.5 R, are comparable at about 1.7 R and become significantly larger than the H0 velocities above 2 R. There is a tendency for the O5+ line of sight velocity distribution in concentrations of polar plumes to be more narrow than those in regions away from such concentrations. UVCS/SOHO has identified 31 spectral lines in the extended solar corona.  相似文献   

8.
To improve the accuracy of the real time topside electron density profiles given by the Digisonde software a new model-assisted technique is used. This technique uses the Topside Sounder Model (TSM), which provides the plasma scale height (Hs), O+–H+ transition height (HT), and their ratio Rt = Hs/HT, derived from topside sounder data of Alouette and ISIS satellites. The Topside Sounder Model Profiler (TSMP) incorporates TSM and uses the model quantities as anchor points in construction of topside density (Ne) profiles. For any particular location, TSMP calculates topside Ne profiles by specifying the values of foF2 and hmF2. In the present version, TSMP takes the F2 peak characteristics – foF2, hmF2, and the scale height at hmF2 – from the Digisonde measurements. The paper shows results for the Digisonde stations Athens and Juliusruh. It is found that the topside scale height used in Digisonde reconstruction is less than that extracted from topside sounder profiles. Rough comparison of their bulk distributions showed that they differ by an average factor of 1.25 for locations of Athens and Juliusruh. When the Digisonde scale heights are adjusted by this factor, the reconstructed topside profiles are close to those provided by TSM. Compared with CHAMP reconstruction profiles in two cases, TSMP/Digisonde profiles show lower density between 400 and 2000 km.  相似文献   

9.
Outgassing from materials as well as deliberate gaseous and liquid releases create contaminant clouds around spacecraft that can degrade both instrumentation and measurements. This paper describes a new method for estimating outgassing water vapor concentrations around space vehicles. Water vapor ions measured in the course of a rocket experiment performed at Eglin AFB, Florida, on December 12, 1980 at 2311 UT are utilized to demonstrate the technique. The H2O concentration near the payload's surface is calculated using the rate coefficient for the fast charge transfer process, O+ + H2O + H2O+ + O, the source of the observed water vapor ions. It is found that the measured H2O+ ions were produced within 3–4 cm of the sampling plate's surface and that the average H2O pressure over this distance was relatively constant on ascent at 8 × 10?6 torr, within a factor two, implying a steady outgassing rate.  相似文献   

10.
Recent in situ measurements with balloon borne quadrupole mass spectrometers, between 20 and 45 km altitude, are reviewed and discussed.The major stratospheric positive ions observed are proton hydrates [H+(H2O)n] and non proton hydrates of the form H+Xm(H2O)2. The data analysis allows a derivation of the vertical mixing ratio profile of X (most probably CH3CN), which is compared with recent model calculations. From negative ion composition data, showing the presence of NO3? and HSO4? cluster ions, the density of sulfuric acid in the stratosphere is deduced. The implications of these findings on our understanding of the sulfur chemistry is briefly treated.Finally some other aspects such as contamination, cluster break up and the use of stratospheric ion mass spectra for determination of thermochemical data and other minor constituents are discussed.  相似文献   

11.
A theoretical model is developed to study the Hα and Hβ volume emission rates in proton auroras. The Hα and Hβ photon yields are deduced by using the recent experimental cross-sections. These photon yields are then coupled with the primary proton fluxes to get the altitude profiles of the emissions. The prediction of the altitude profiles are found in good agreement with the auroral measurements. The effects of various modes of proton precipitation on the emission intensities (IHα and IHβ) are discussed and a comparison is made with the earlier theoretical models. It is also found that the intensity ratio IHα/IHβ varies between 5 and 6.  相似文献   

12.
As part of the MAP/WINE Campaign 1983/84 a liquid helium cooled infrared grating spectrometer measured night zenith radiances of CO2, O3, and H2O in the mesosphere and lower thermosphere. From a comparison of the measured spectral radiances with results from LTE radiative transfer calculations atmospheric temperatures and concentration profiles of H2O and O3 were determined, showing some interesting features. The ozone densities obtained appear to contradict model predictions based upon the assumption that ozone is in photochemical equilibrium at mesospheric heights. Since the ozone density distribution shows quite similar structures as the vertical wind profile, transport effects seem to play a major role in the mesospheric ozone formation.  相似文献   

13.
The Limb Infrared Monitor of the Stratosphere (LIMS) experiment is a limb scanning infrared sounder designed to measure vertical temperature profiles and the concentrations of key chemical compounds which are important in the stratospheric ozone-nitrogen photochemistry. This paper describes results from the O3 and HNO3 channels with emphasis on validation of the data. Similar discussions of results from the other channels are presented in two companion papers published in these proceedings.  相似文献   

14.
We report the first results of ground-based millimeter-wave measurements of 183 GHz atmospheric water vapor spectra from Atacama highland (4800 m alt.), Chile. The measurements were carried out in December 2005 by using a spectroscopic radiometer equipped with a superconductive heterodyne receiver. A conspicuous H2O spectrum at 183 GHz was detected with an integration time of only 1.5 min, and this is the first high frequency-resolution H2O spectrum at 183 GHz obtained in the southern subtropical region. The vertical profile of H2O volume mixing ratio between 40 and 64 km were retrieved from the spectrum by using the modified optimal estimation method.  相似文献   

15.
The ionospheric characteristics of the F2 layer peak have been measured with ionosondes from the ground or with satellites from space. The most common characteristics are the F2-peak density NmF2 and peak height hmF2. In addition to these two parameters this paper studies the F2-peak scale height. Comparing the median values of hmF2 and NmF2 obtained from topside and bottomside sounding shows good agreement in general. The Chapman scale height values for the F2 layer peak derived from topside profiles, Hm,top, are generally several times larger than Hm,bot derived from bottomside profiles.  相似文献   

16.
Our current knowledge on the composition of the Venus atmosphere in the altitude range from the surface to 100 km is compiled. Gases that have been measured, and whose mixing ratios are assumed to be constant with altitude, are CO2, N2, He, Ne, Ar, and Kr. Gases that have been identified in the lower and/or middle atmosphere, but whose mixing ratios may depend on altitude, latitude and/or local time, are CO, H2O, HCl, HF, and SO2. Conflicting data or only upper limits exist on some important trace gases, such as O2, H2, and Cl2. The latter two are key constituents in the photochemistry of the middle atmosphere of Venus. The chapter concludes with a listing of the isotopic abundances of elements measured in the Venus atmosphere.  相似文献   

17.
Statistical mid-latitude models of altitude distribution of temperature, water vapor, ozone, carbon dioxide and trace gases (CO, CH4, N2O, NO, NO2) are considered. The mean characteristics of altitude profiles of these parameters, as well as their time and space variability, have been taken into account. The statistical regional models were constructed using a temperature-humidy complex. The considered statistical mid-latitude models have been constructed as applied to solutions of the problems on remote sounding of the atmosphere and underlying surface from outer space.  相似文献   

18.
Four important sampling techniques are briefly reviewed: Selective sampling on impregnated filters for measuring acidic gases, the matrix isolation technique for measuring radicals, whole air grabsampling and whole air cryogenic sampling for measuring stable source gases.Vertical profiles of H2, CH4, CO, N2O, CFCl3 and CF2Cl2 resulting from gas chromatographic analysis of whole air samples collected with a cryogenic sampler are presented. Year-to-year variations are observed for H2, CH4 and N2O above 25 km, while CFCl3 and CF2Cl2 mixing ratios show a noticeable increase between 1977 and 1979 at almost every height level.The CO2 mixing ratio is not constant with height but rather decreases from 332 ppmV at 10 km to 325 ppmV at 30 km.The vertical distribution of methyl chloride is characterized by a rapid decrease from 600 pptV in the troposphere to less than 10 pptV at 32 km in agreement with model results.  相似文献   

19.
The absorption anomaly of Lyman-alpha radiation in satellite occultation experiments is known as the fact that extinction above 100 km is much stronger than absorption by atmospheric O2 alone would explain. Additional absorption by NO or H2O has been suggested but none has been clearly identified so far. The additional absorption occurs predominantly in middle and high latitudes of the winter hemisphere, but has also been found in equatorial latitudes. Recent measurements of NO would explain the Lyman-alpha absorption anomaly. The high densities of the additional Lyman-alpha absorber at lower latitudes could be explained by transport processes through global circulation systems of the higher thermosphere. Structural variations of the neutral gas derived from occultation measurements seem to indicate that thermospheric low pressure systems in mid latitudes modulate the transport of tracer constituents and heat energy from higher latitudes to the equator.  相似文献   

20.
The topside ionosphere scale height extracted from two empirical models are compared in the paper. The Topside Sounder Model (TSM) provides directly the scale height (HT), while the incoherent scatter radar ionospheric model (ISRIM) provides electron density profiles and its scale height (HR) is determined by the lowest gradient in the topside part of the profile. HT and HR are presented for 7 ISR locations along with their dependences on season, local time, solar flux F10.7, and geomagnetic index ap. Comparison reveals that HT values are systematically lower than respective HR values as the average offset for all 7 stations is 55 km. For the midlatitude stations Arecibo, Shigaraki, and Millstone Hill this difference is reduced to 43 km. The range of variations of HR is much larger than that of HT, as the HT range overlaps the lower part of the HR range. Dependences on ap, DoY and LT are much stronger in the ISRIM than in TSM. This results in much larger values of HR at higher ap. Diurnal amplitude of HR is much larger than that of HT, with large maximum of HR at night. The present comparison yields the conclusion that the ISR measurements provide steeper topside Ne profiles than that provided by the topside sounders.  相似文献   

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