Nitrous oxide ultraviolet absorption spectrum at stratospheric temperatures (original) (raw)
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Atmospheric Chemistry and Physics, 2010
Absorption cross sections of nitrous oxide (N 2 O) and carbon tetrachloride (CCl 4 ) are reported at five atomic UV lines (184.95, 202.548, 206.200, 213.857, and 228.8 nm) at temperatures in the range 210-350 K. In addition, UV absorption spectra of CCl 4 are reported between 200-235 nm as a function of temperature (225-350 K). The results from this work are critically compared with results from earlier studies. For N 2 O, the present results are in good agreement with the current JPL recommendation enabling a reduction in the estimated uncertainty in the N 2 O atmospheric photolysis rate. For CCl 4 , the present cross section results are systematically greater than the current recommendation at the reduced temperatures most relevant to stratospheric photolysis. The new cross sections result in a 5-7% increase in the modeled CCl 4 photolysis loss, and a slight decrease in the stratospheric lifetime, from 51 to 50 years, for present day conditions. The corresponding changes in modeled inorganic chlorine and ozone in the stratosphere are quite small. A CCl 4 cross section parameterization for use in atmospheric model calculations is presented.
Thermospheric nitric oxide infrared emissions measured by CRISTA
Advances in Space Research, 1997
AEm-RAcT In November 1994 the CRISTA (Cryogenic Infrared Spectrometers and Telescopes of the Atmosphere) experiment measured mid and far infrared spectra Tom the Earth limb. One of the spectral channels covered the 5.3 pm (Av = 1) band of nitric oxide. A first analysis of the data of this channel is presented. Large enhancements of the 5.3 urn band radiances were observed at high northern and at high southern magnetic latitudes. The measured intensities were a factor of 4-6 above those found at low latitudes.
Global observations of nitric oxide in the thermosphere
Journal of Geophysical Research, 2003
Nitric oxide density in the lower thermosphere (97-150 km) has been measured from the polar-orbiting Student Nitric Oxide Explorer (SNOE) satellite as a function of latitude, longitude, and altitude for the 2 1/2 year period from 11 March 1998 until 30 September 2000. The observations show that the maximum density occurs near 106-110 km and that the density is highly variable. The nitric oxide density at low latitudes correlates well with the solar soft X-ray irradiance (2-7 nm), indicating that it is the solar X-rays that produce thermospheric nitric oxide at low and midlatitudes. Nitric oxide is produced at auroral latitudes (60°-70°geomagnetic) by the precipitation of electrons (1-10 keV) into the thermosphere. During high geomagnetic activity, increased nitric oxide may be present at midlatitudes as the result of meridional winds that carry the nitric oxide equatorward.
Journal of Geophysical Research, 1985
The ultraviolet nitric oxide spectrometer (UVNO) experiment on the Atmosphere Explorer D (AE-D) satellite measured thermospheric nitric oxide during the winter of 1974-1975 using resonant fluorescence from the 1-0 gamma band of the molecule. Almost complete latitude coverage was obtained, but the observations were confined to morning local times close to 0900. The 1-0 gamma band intensity profiles measured by the instrument were inverted to provide vertical profiles of the NO number density between about 90 and 200 km. Typically, the measured NO concentrations reached a maximum between altitudes of 100 and 110 km, and more NO was observed at higher latitudes than at low latitudes, in agreement with previous observational studies. The shape of the NO profile was also found to be a function of latitude, with a plateau appearing in the profile near 130 km for low latitudes and mid-latitudes in the winter hemisphere. 1. INTRODUCTION Nitric oxide density profiles for thermospheric altitudes have been measured by experiments on many rocket flights over the last decade or two [c.f. G•rard et al., 1983; McCoy, 1983a]. These rocket experiments have provided detailed information on the altitude distribution of NO at particular times and locations. However, NO is quite variable both spatially and temporally, which makes global observations of it desirable. OGO 4 measured NO both at mid-latitudes and in the auroral region [Rusch, 1973; Rusch and Barth, 1975; G•rard and Barth, 1977]. Nitric oxide tangential column densities for thermospheric altitudes were also measured by the ultraviolet spectrometers (UVNO)on both the Atmosphere Explorer C and D satellites (AE-C and AE-D). These instruments, which were described by Barth et al. [1973], measured sunlight fluorescently scattered in the 1-0 gamma band of the molecule at 2150/•,. Stewart and Cravens [1978] analyzed NO data from AE-C for 105 km for magnetically quiet times, and Cravens and Stewart [1978] did the same for higher levels of magnetic activity. Cravens et al. [1979] further studied NO at 105 km but also presented data for NO at 200 km from orbits during which AE-C was despun. Cravens [1981] presented virtually all despun AE-D data for an altitude of 200 km. All these satellite studies emphasized the horizontal and temporal variability of nitric oxide, whereas the rocket studies emphasized the details of the vertical distribution. Both rocket and satellite studies have demonstrated that NO is almost always more abundant at higher latitudes, particularly in the auroral regions where large concentrations of Copyright 1985 by the American Geophysical Union. Paper number 4A8414. 0148-0227/85/004A-8414505.00 NO in excess of 108 cm-3 have been observed. Cravens and Stewart [1978] determined the manner in which NO in the lower thermosphere (i.e., at 105 km, which is near the peak of a typical NO altitude distribution) varies with latitude, longitude, and magnetic activity. Stewart and Cravens [1978] explored the local time and seasonal variations of NO. These studies showed that NO at middle and high, and sometimes even low, latitudes is correlated with the Ap index of magnetic activity. A large latitudinal gradient of NO is present during magnetically active times. Cravens et al. [1979] demonstrated that these large observed latitudinal gradients could not be explained using the current one-dimensional theories of thermospheric odd nitrogen, and they concluded that significant horizontal trans
Journal of Geophysical Research, 1985
The solar backscattered ultraviolet spectral radiometer on the Nimbus 7 satellite routinely measures fluorescence emissions from the nitric oxide (1, 4) gamma band that are imposed on the large Rayleighscattered signal in the wavelength range 255-256 nm. The gamma band feature, when isolated from the background radiance, provides information on the seasonal and latitudinal variations in the nitric oxide column abundance over the altitude region from 40 to 45 km upward through the thermosphere. At latitudes from 30 ø to 45 ø in the northern hemisphere the measurements show an annual cycle with maximum nitric oxide abundance in summer. The southern hemisphere pattern is qualitatively similar to this, although the amplitude of the seasonal variation is substantially smaller. The most prominent feature of the data base is a large maximum in nitric oxide emission that develops poleward of 45 ø latitude in both hemispheres during late autumn and early winter. These maxima dissipate rapidly as spring approaches and are no longer evident in the data for northern hemisphere March and southern hemisphere September. 1982]. At the time of this work the SBUV continuous-scan data base was not available for analysis, and in any case the infrequent use of this observing mode restricts the quantity of information collected. However, the shortest-wavelength discrete-mode channel, encompassing the 255-256 nm region, Copyright 1985 by the American Geophysical Union. Paper number 4D 1402. 0148-0227/85/004 D-1402505.00 receives a contribution from the (1, 4) gamma band, and if properly interpreted, these data can provide information on the global column abundance of nitric oxide at levels above 40-45 km. The objective of this work is to develop the methodology required to isolate this emission from the Rayleighscattered background and to apply it to the SBUV data base to determine the latitudinal and seasonal behavior of nitric oxide in the upper atmosphere. ORIGIN OF THE NITRIC OXIDE EMISSION Incoming solar radiation near 214.9 nm enters the earth's atmosphere where it is absorbed by ozone, molecular oxygen, ß ß ß ß ß ß ß ß ß ß 0.06 '- .....-0.0 MONTH ß ß ß ß ß ß ß Fig. 4. Monthly averaged values of the ratio of 255-256 nm NO 0.0 ß ß ß ß ß 4 ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß _• ß ß ß ß ß ß ß ß ß ß • ß ß ß ß J ß ß ß ß ß ß ß ß ß ß ß ß ß ß ß A
On the behavior of nitrogen oxides in the stratosphere
Pure and Applied Geophysics PAGEOPH, 1973
A summary is presented of the relative importance of the principal aeronomic processes determining the vertical distribution of NO-NOa in the stratosphere. Formation and destruction of nitric oxide are considered with transport processes for steady-state conditions. Estimates of the vertical distribution of NO~ are made for extreme conditions of the eddy diffusion coefficient. It is pointed out that NO is determined by the values which are adopted for its photodissociation coefficient which is related to the absorption of solar radiation in the Schumann-Runge bands of molecular oxygen.
Journal of Geophysical Research, 2004
A time-dependent thermospheric model has been used to calculate the nitric oxide density in the lower thermosphere for a 935-day period, 11 March 1998 to 30 September 2000. This model uses daily values of the observed solar soft X-ray irradiance (2-7 nm) as an energy input parameter. The model does not include an energy input from auroral electron precipitation. The results of the model calculation of nitric oxide density at 110 km were compared with observations of nitric oxide density made with the Student Nitric Oxide Explorer (SNOE) for the 935-day period. At the equator the model calculations and the observations agree very well with a linear correlation coefficient of 0.876. The correlation coefficient remains high for the altitude region 107-117 km, the region where solar soft X-rays (2-7 nm) are the major source of nitric oxide production. The comparison of the model calculations with the observations as a function of latitude show that there is excess nitric oxide poleward of 30°N and S latitude particularly during the fall-winter season. We believe that the source of this excess nitric oxide is the nitric oxide that is produced in the auroral region (65°-75°N and S geomagnetic latitude) by precipitating auroral electrons. We believe that aurorally produced nitric oxide is transported equatorward by horizontal winds. At midlatitudes the excess nitric oxide decays to about half of its initial value in one day. At times of large geomagnetic storms we believe that aurorally produced nitric oxide is transported all the way to the equator by horizontal winds. The excellent correlation of the model calculations and the SNOE observations of nitric oxide at 110 km between 30°S and 30°N support the hypothesis that solar soft X-rays are the source of the variability of nitric oxide in the thermosphere at low latitudes.
ATMOS/ATLAS 1 measurements of thermospheric and mesospheric nitric oxide
Journal of Geophysical Research, 1995
The atmospheric trace molecule spectroscopy (ATMOS) instrument obtained solar occultation spectra of the terrestrial atmosphere during the Atmospheric Laboratory for Applications and Science (ATLAS 1) mission of March 26-April 4, 1992. During this time, Ap varied between 11 and 18 while the F10.7 index was near 192. The analyses of the 5.3-/am spectral data to derive nitric oxide densities in the lower thermosphere and mesosphere are described here. The results show that a peak NO density of 1.0 x 108 cm -3 occurs at 105 _+ 2.5 km for the latitude range 38øN-58øS. The density values are higher than previously reported using UV measurements. These measurements worsen the discrepancy with photochemical models at low latitudes where models already underpredict nitric oxide. 16,839 16,840 KUMAR ET AL.: ATMOS/ATLAS 1 MEASUREMENTS OF NO IN THERMOSPHERE 1.00 0.80 113 km
Day and night profiles of tropospheric nitrous oxide
Journal of Geophysical Research, 1986
Daytime and nighttime vertical profiles of the tropospheric trace gas N20 were determined from grab sample collections off the Atlantic and Gulf coasts of Florida. The grab samples were collected during the week of October 7-13, 1984, from a Lear Jet during descent spirals over an altitude range of 12.5-0.3 km in approximately 1.2-km intervals. During this period there were two distinct airflow regimes sampled: the surface boundary layer (< 2 km), in which the wind direction was typically easterly; and the regime above the boundary layer, which was predominantly characterized by westerly flow. N20 mixing ratios, normalized to dry air, were determined from 148 daytime and nighttime samplings. N20 was found to be uniformly mixed at all altitudes at 301.9 4-2.4 parts per billion by volume.