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1.
Zonal mean mixing ratios of ozone and NO2 measured by SAGE II on several days in March and April, 1985 are compared against zonal means for this time of year previously measured by SAGE I, SBUV, and LIMS. After allowing for calculated diurnal variations of these gases, agreement within 15% is found for ozone and 20% for NO2. It is noted that the profile error bars given on the SAGE II data tapes need to be carefully interpreted and that the measured tropical variances suggest that these error bars are being somewhat overestimated. Planetary waves in both ozone and NO2 in the middle stratosphere should be derivable from the SAGE II measurements.  相似文献   

2.
Vertical profiles of stratospheric nitrogen dioxide (NO2) have been retrieved from moderate resolution lunar occultation transmission spectra measured by Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on board the European Environmental Satellite (ENVISAT). These measurements were taken over the high southern latitude of 50°–90° during the period of 2003–2005. To assess the accuracy of the retrieved NO2 profiles, the SCIAMACHY nighttime NO2 profiles were compared with NO2 profiles retrieved from sunrise solar occultation spectra measured by the Halogen Occultation Experiment (HALOE) and the Stratospheric Aerosol and Gas Experiments II (SAGE II) using a photochemical correction model. The validation results show good agreement of SCIAMACHY lunar occultation NO2 with scaled HALOE and SAGE II profiles. The relative mean differences (rmd) with scaled HALOE profiles are within −13% to +5% and standard deviations (rms) of the relative differences are within 3–19% between 25 and 38 km. The rmd and rms with scaled SAGE II NO2 profiles are in the range of −9 to +7 and 10–17% respectively between 22 and 39 km.  相似文献   

3.
4.
The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE has been tested by comparing their results with each other and with results obtained by other techniques (lidar, dustsonde, filter, impactor). The latter type of comparison has required the development of special techniques that (1) convert the quantity measured by the correlative sensor (e.g. particle backscatter, number, or mass) to that measured by the satellite sensor (extinction), and (2) quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, vortex structure, etc.). Hence, we conclude that the satellite measurements are valid.  相似文献   

5.
The satellite sensors SAM II and SAGE have been developing a global data base on stratospheric aerosols since they were launched in October 1978 and February 1979, respectively. The validity of this data base has been tested by numerous comparisons with other measurements made by lidars, balloon-borne particle counters, and aircraft-borne impactors and filters. Because the satellite sensors measure extinction and the correlative sensors measure other properties (e.g., backscatter, number, mass), special techniques are required to convert each measured property to other properties and to quantify conversion uncertainties and measurement uncertainties. Use of these techniques in two major comparative experiments shows that the SAM II and SAGE extinction measurements agree with each other and with values derived from dustsonde, lidar, and filter measurements. In addition, the comparative experiments have highlighted the uncertainties of each type of sensor and stimulated further efforts to reduce these uncertainties.  相似文献   

6.
7.
The SAM II and SAGE satellite systems have provided to date more than 5 years and almost 3 years, respectively, of data on atmospheric aerosol profiles on a near-global scale. Studies with these unique data sets are developing a global aerosol climatology for the first time and have shown the existence and quantification of polar stratospheric clouds (PSC's) and tropical stratospheric cirrus. In addition, a tropospheric cirrus climatology is evolving. Since these two experiments were launched, a series of large volcanic eruptions have occurred which have greatly impacted the stratospheric aerosol loading. The aerosol layer produced by the eruption of El Chichon, for example, increased the 30 mb temperatures in the northern tropics by as much as 4°C for 6 months after the eruption. This paper will describe in detail, from a climate perspective, the evolving aerosol and cloud climatologies as a function of space and time, and show the stratospheric dynamics of volcanic injections and their enhancements on stratospheric optical depth and mass loading.  相似文献   

8.
Since the fall of 1978, two Earth-orbiting spacecraft sensors, SAM II, for Stratospheric Aerosol Measurement II, and SAGE, for Stratospheric Aerosol and Gas Experiment have been monitoring the global stratospheric aerosol. These experiments use the Sun as a source to make Earth-limb extinction measurements during each spacecraft sunrise and sunset. This paper describes the global aerosol data base (climatology) that is evolving. Seasonal and hemispheric variations such as the springtime layer expansion with warming temperatures and the local wintertime polar stratospheric clouds (PSC's) will be described. The PSC's enhance extinction by up to two orders of magnitude and optical depths by as much as an order of magnitude over the background 1000 nm values of about 1.2 × 10?4 km?1 and 1.3 × 10?3, respectively. The detection and tracking of a number of volcanoes whose effluents penetrated the tropopause are also described. The mass of new aerosol injected into the stratosphere from each volcano is estimated. The May 1980 eruption of Mount St. Helens, for example, produced about 0.32 × 109 kg of new stratospheric aerosol enhancing the Northern Hemispheric aerosol by more than 100 percent.  相似文献   

9.
The TIROS-N operational meteorological satellite observing system will have the capability of determining global ozone amounts from two instruments by 1985. The TIROS Operational Vertical Sounder (TOVS) yields total ozone amounts through measurements of atmospheric infrared radiances. The Solar Backscatter Ultraviolet (SBUV/2) spectrometer yields total ozone amounts and vertical ozone profiles through measurements of the solar ultraviolet radiation backscattered by the atmosphere. The current operations plan calls for single satellites containing both instruments system with local afternoon equator crossing times. They will be launched at approximately 18 month intervals.The satellite ozone products will require verification using commonly accepted references. For total ozone, Dobson spectrophotometer determinations are to be used. For vertical profiles, no clear choice now exists among balloon-launched chemical sondes, rocket-launched optical sondes or Dobson Umkehr measurements. The applicability and use of these measurement systems are discussed with emphasis on the need for the verification data consistent with the operational satellite lifetimes.Another major source of data for verification is other satellite systems. Comparisons of vertical ozone profiles from several concurrent satellites is discussed. This includes results from SAGE, LIMS and SBUV.  相似文献   

10.
Stratospheric ozone observations by the SAGE and SBUV satellite instruments in March and April, 1979 have been analyzed. All SAGE profiles have been smoothed vertically over 8 km to provide some compatibility with the SBUV vertical resolution. Comparing the zonal mean ozone mixing ratios against smoothed LIMS profiles, it is inferred that SAGE is systematically overestimating ozone by approximately 20% at tropical latitudes at pressures lower than 5 mb and that SBUV is underestimating ozone by approximately 15% at 50–70° latitude at 10 mb. A comparison of the longitudinal variations of ozone by SBUV and SAGE is made and the detectability of planetary waves in ozone is emphasized. The uncorrelated portion of the SAGE variances are found to be approximately consistent with the SAGE noise model. Based on the correlated variances, the amplitudes of the smoothed SAGE planetary waves in ozone are found to be the same, on average, as in the SBUV experiment at mid-latitudes between 1 and 10 mb. Planetary wave detectability is illustrated during two several day periods at mid-latitudes and a persistent and theoretically-consistent relationship between ozone and temperature is noted. These examples, however, indicate that differences between ozone planetary wave amplitudes derived from the two sensors may occur when there is a strong vertical gradient in wave amplitude.  相似文献   

11.
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   

12.
Transmittance functions as well as inversion algorithms have been developed for deriving H2O profiles from radiometer measurements. These computer programs have been applied to evaluate own stratospheric balloon occultation measurements and LIMS (Limb Infrared Monitor of the Stratosphere) radiance measurements in the H2O channel. The results are compared with the H2O profiles in the LIMS data archive. The differences between corresponding H2O profiles are discussed in dependence of altitude and latitude.  相似文献   

13.
GOMOS (Global Ozone Monitoring by Occultation of Stars) and MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) are remote sensing instruments on board the European Space Agency’s Envisat satellite. GOMOS and MIPAS have been designed for observations of stratospheric and mesospheric constituents, including ozone and nitrogen dioxide. Both instruments have a good global coverage of observations and can provide data also from the polar regions. In this paper, we compare night-time NO2 data from GOMOS with those from MIPAS. We present statistics of selected sets of data spanning from the year 2003 to 2006. The results for low-to-mid latitudes show that the two instruments are in a good agreement in the middle stratosphere, the differences being typically less than 5%. In the upper stratosphere, GOMOS observations generally show 15% higher values than those from MIPAS. The bias is in virtually all cases smaller than the combined systematic error of the measurements, giving great confidence in the GOMOS and MIPAS data quality. The result for high mesospheric NO2 mixing ratios observed in the polar regions during winter times indicate a good agreement between GOMOS and MIPAS. In the mesosphere, the difference is less than 35% and smaller than the systematic error. Due to the high mesospheric signal, MIPAS sensitivity decreases in the stratosphere which results in larger differences between the two instruments.  相似文献   

14.
Particulate component of the Mars atmosphere composed by micron-sized products of soil weathering and water ice clouds strongly affects the current climate of the planet. In the absence of a dust storm so-called permanent dust haze with τ  0.2 in the atmosphere of Mars determines its thermal structure. Dust loading varies substantially with the season and geographic location, and only the data of mapping instruments are adequate to characterize it, such as TES/MGS and IRTM/Viking. In spite of vast domain of collected data, no model is now capable to explain all observed spectral features of dust aerosol. Several mineralogical and microphysical models of the atmospheric dust have been proposed but they cannot explain the pronounced systematic differences between the IR data (τ = 0.05–0.2) and measurements from the surface (Viking landers, Pathfinder) which give the typical “clear” optical depth of τ  0.5 from one side, and ground-based observations in the UV–visible range showing much more transparent atmosphere, on the other side. Also the relationship between τ9 and the visible optical depth is not well constrained experimentally so far. Future focused measurements are therefore necessary to study Martian aerosol.  相似文献   

15.
The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) measures scattered sun light also in limb viewing mode (i.e. tangential to Earth’s surface and its atmosphere), which allows determining vertical profiles of atmospheric trace gases. First results on the retrieval of NO2, BrO and OClO profiles from the SCIAMACHY Limb measurements are presented and compared to independent satellite and balloon borne observations.  相似文献   

16.
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   

17.
The Mars Global Surveyor (MGS) Mission is more than just a return to Mars. It represents a qualitatively new type of planetary mission. This is true not only because of the capable instrumentation aboard the spacecraft and the choice of orbit and data rate, but also because of a major beneficial change in our understanding of the interplay between observation and modeling. The Thermal Emission Spectrometer (TES), for example, is capable of taking thousands of infrared spectra per day. The 15 micrometer carbon dioxide band in these spectra can be inverted to obtain atmospheric temperature profiles, amounting to some 15,000–25,000 separate measurements each day. In addition, radio occultations produce fewer, but much higher resolution, temperature and pressure profiles. How is such a quantity of data to be handled? Clearly not in the old-fashioned manner in which a single profile is studied at great length and detail. The quantity of data does not allow this; and the quality of the data does not support it. (A single atmospheric profile is bound to contain small-scale spatial and temporal variation—e.g., gravity waves—that cannot be removed unambiguously, as well as possible errors due to noise in the observations or non-uniqueness of the inversions). Furthermore, much of the atmospheric science of interest (winds, for example) depends on quantities like horizontal temperature gradients that are not directly observed. Instead, the data should be examined collectively with the aid of a model that incorporates our knowledge of the governing physics. Described here are the first results of such a data assimilation exercise with TES observations during the aerobraking hiatus period at Ls ≈ 200.  相似文献   

18.
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   

19.
The images were constructed for three aerosol cloud distribution types: uniform, one with a cavity in the center (shell) and one with a dense core (core with “wings”). Differences between images of optically thick and optically thin clouds for these three distribution types of particles and warious view angles are discussed. Calculated results are compared with experimental data from aerosol clouds observations.  相似文献   

20.
Investigations to measure the vertical optical thickness of aerosols over ocean surfaces has been conducted using several different satellite sensors. Landsat 1 and Landsat 2 data originally confirmed that a linear relationship exists between the upwelling visible radiance and the aerosol optical thickness (about 90% of this thickness is generally in the lowest 3 km of the atmosphere). Similar relationships have also been found for sensors on GOES-1, SMS-2, NOAA-5, and NOAA-6 satellites. The linear relationship has been shown theoretically to vary with the aerosol properties, such as size distribution and refractive index, although the Landsat data obtained at San Diego showed little variability in the relationship. The differences between the results found for the various satellite sensors are discussed, and are attributed mainly to uncertainties in the calibration of the sensors. To investigate the general applicability of the technique to different locations, a global-scale ground truth experiment was conducted with the AVHRR sensor on NOAA-6 to determine the relationship at eleven ocean sites around the globe. Analysis of the data shows good agreement between the satellite and ground truth values of the aerosol optical thickness, and indicates that the technique has global application. At two of the sites, multispectral radiometric measurements of the Junge aerosol size distribution parameter were made, and showed good agreement with a value inferred from the AVHRR Channels 1 and 2 radiances.  相似文献   

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