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NASA NTRS2022

SAGE III/ISS Ozone and NO2 Validation Using Diurnal Scaling Factors

We developed a set of solar zenith angle, latitude- and altitude-dependent scaling factors to account for the diurnal variability in ozone (O3) and nitrogen dioxide (NO2) when comparing Stratospheric Aerosol and Gas Experiment (SAGE) III/ISS observations to observations from other times of day. The scaling factors are calculated as a function of solar zenith angle from the four-dimensional output of a global atmospheric chemistry model simulation of 2017–2020 that shows good agreement with observed vertical profiles. Using a global atmospheric chemistry model allows us to account for both chemically and dynamically driven variability. Both year-specific scale factors and a multi-year monthly climatology are available to decrease the uncertainty in inter-instrument comparisons and allow consistent comparisons between observations from different times of day. We describe the variability in the diurnal scale factors as a function of space and time. The quasi-biennial oscillation (QBO) appears to be a contributing factor to interannual variability in the NO2 scaling factors, leading to differences between years that switch sign with altitude. We show that application of these scaling factors improves the comparison between SAGE III/ISS and OSIRIS NO2 and between SAGE III/ISS and OMPS LP, OSIRIS, and ACE-FTS O3 observations. The comparisons between SAGE III/ISS O3 for sunrise or sunset vs. Microwave Limb Sounder (MLS) daytime or nighttime observations are also more consistent when we apply the diurnal scaling factors. There is good agreement between SAGE III/ISS V5.2 ozone and correlative measurements, with differences within 5 % between 20 and 50 km when corrected for diurnal variability. Similarly, the SAGE III/ISS V5.2 NO2 agreement with correlative measurement is mostly within 10 %. While the scale factors were designed for use with SAGE III/ISS observations, they can easily be applied to other observation intercomparisons as well.

Sarah A. Strode↗

NASA NTRS1972

Quenching of the fluorescence of NO2

The fluorescence yield of NO2 was monitored at 25 C with incident wavelengths of 4047, 4358, and 4800A at fluorescence wavelengths of 4860, 5577, and 6300A. The NO2 pressure was varied between 0.004 and 0.080 torr. Measurements were taken both in the absence of foreign gases and in the presence of up to 30 torr. He, N2, and O2 at each NO2 pressure. In the absence of foreign gases, the self quenching follows a Stern-Volmer quenching mechanism, but foreign-gas quenching shows marked deviations from this mechanism. Both from lifetime and kinetic considerations, it is argued that the electronic state formed by absorption of the radiation cannot be the emitting state. Emission occurs from several vibrational levels of the emitting state, the various vibrational levels being formed by collisional cascade reactions. The appropriate quenching rate constant ratios were measured and tabulated. Even the two electronic state mechanism is insufficient to explain all the observations.

Braslavsky, S.↗

NASA NTRS1976

The reaction of NH2 with NO2

Ammonia (NH3) was photolyzed at 213.9 nm in the presence of NO2 at 25 C in order to study the reactions of NH2 with NO2. The products included NO, with a quantum yield of 1.0. The other measured products of the reaction were N2 and N2O with respective quantum yields of 0.94 plus or minus 0.10 and 0.3 in the presence of small amounts of He and 0.65 plus or minus 0.15 and 0.13 in the presence of a large excess of He. The quantum yield for NO2 consumption was 6.0 plus or minus 2.0 in the absence of He. These results are explained in terms of various reactions.

Jayanty, R. K. M.↗

NASA NTRS1976

Absolute integrated intensity for the 3.44-microns NO2 band

A grating monochromator infrared spectrometer and a curve of growth technique were used to obtain the absolute integrated intensity for the 3.44 micron NO2 vibration-rotation band at very small NO2 partial pressures. The intensity was found to be 78.9 plus or minus 1.6/cm/(atm cm) at 296 K at the 95% confidence level. The study has relevance to the infrared spectral measurement of atmospheric NO2.

Shafer, J. H.↗

NASA NTRS1977

NO-NO2 measurements in a methane-fueled swirl-stabilized combustor

Exhaust plane measurements of NO and NO2 emissions from a methane-fueled swirl-stabilized combustor are reported. Samples were obtained by water-cooled probes and analyzed by chemiluminescent and UV absorption techniques. The combustor consists of two confined concentric jets having swirl. The inner jet flows premixed fuel and air, the outer jet is air. Variable outer jet swirl allows operation with jets swirling either in the same or opposite directions (co- or counter-swirl), and the combustion is stabilized by the resulting recirculation zone formed on the combustor centerline. Swirl conditions strongly affect the NOx emissions because of the influence of swirl on the combustion process. In the co-swirl conditions, the inner flow reaches high temperatures, and the correspondingly high NOx emissions are primarily NO. Under counter-swirl conditions much lower values of total NO are found, and these emissions are almost entirely NO2. In this case vigorous mixing in the inter-jet shear layer leads to severe flame quenching and lower temperatures. Formation of NO2 is associated with quenching processes in the combustor and is thought to be formed via NO oxidation by HO2 free radicals.

Oven, M. J.↗

NASA NTRS1979

The reactions of CCl2FO2 with NO and NO2 and the thermal decomposition of CCl2FO2NO2

CCl2FO2 radicals are produced in the stratosphere from the oxidation of CCl2F radicals produced from the photodissociation of CCl3F. The reactions of CCl2FO2 with NO and NO2 were studied by steady state photolysis at 1 atm and 286-305 K. The reactions were CCl2FO2 + NO yields CCl2FO + NO2 and CCl2FO2 + NO2 (+M) yields CCl2FO2NO2 (+M) with k3/k4 = 0.58 plus or minus 0.10 over this temperature range.

Simonaitis, R.↗

NASA NTRS1984

Stratospheric NO and NO2 profiles at sunset from analysis of high-resolution balloon-borne infrared solar absorption spectra obtained at 33 deg N and calculations with a time-dependent photochemical model

Simultaneous stratospheric vertical profiles of NO and NO2 at sunset were derived from an analysis of infrared solar absorption spectra recorded from a float altitude of 33 km with an interferometer system during a balloon flight. A nonlinear least squares procedure was used to analyze the spectral data in regions of absorption by NO and NO2 lines. Normalized factors, determined from calculations of time dependent altitude profiles with a detailed photochemical model, were included in the onion peeling analysis to correct for the rapid diurnal changes in NO and NO2 concentrations with time near sunset. The CO2 profile was also derived from the analysis and is reported.

Rinsland, C. P.↗

NASA NTRS1984

Oxidation of SO2 by NO2 and O3 on carbon - Implications to tropospheric chemistry

The oxidation of SO2 to sulfate in air at 65 percent relative humidity on carbon particles was investigated gravimetrically in the presence of NO2 and O3. Approximately 1 mg samples of carbon black were exposed to continuously flowing ppbv mixtures of SO2, SO2 + NO2 and SO2 + O3 for prescribed periods of time before desorption into dry N2. Wet chemical analysis of the particles followed desorption. NO2 and O3 were found to have little, if any, effect relative to air on sulfate yields at the concentrations studied.

Cofer, W. R., III↗

NASA NTRS1985

Ram vehicle glow spectrum - Implication of NO2 recombination continuum

An experiment was operated on several Space Shuttle missions to provide spatial and spectral distributions of a ram glow associated with the Orbiter. The most recent data featured resolved spectrum and imagery of the glow with spectroscopic resolution of 34 A FWHM between 4000 and 8000 A. The spectrum of the glow on the Shuttle tail pod could be clearly separated from spectrum of the reflected light from the Orbiter. Analysis and comparison have been performed which strongly suggest the emission originates from recombination continuum of NO2. Both fast recombination (high temperature) and the spectral dependence in lifetime can describe the spectral difference. If the recombined NO2 retains 25 percent of the kinetic energy of the ram OI, the thickness of the glow layer can be explained by the lifetime of NO2 (2B1) recombination emission.

Swenson, G. R.↗

NASA NTRS1985

Measurement of polar stratospheric NO2 from the 23rd and 24th Japanese Antarctic Research Expedition (JARE) balloon experiments

As a part of the Japanese activities of MAP in the Antarctica, balloon-borne measurements of the stratospheric NO2 profile were planned and carried out by the JARE 23rd and 24th wintering parties. Few results have been reported so far as the stratospheric NO2 profile at high latitude. There were no reported balloon measurements carried out in the Southern Hemisphere. Profiles are presented for the first balloon-borne measurement of the stratospheric NO2 in the Antarctica. Three balloons named JA21, JA25 and JA26 were launched from Syowa Station (69 deg S, 35.6 deg E) using 5000 cu. cm plastic balloons. JA21 balloon was launched on November 24, 1982, and JA25 and JA26 balloons on November 12 and 20, 1983, respectively.

Shibasaki, K.↗

NASA NTRS1986

Seasonal behavior of NO2 in the winter stratosphere - Inferred NO(x)

An analysis is performed of Solar Mesosphere Explorer (SME) data for the first 90 days of 1982, when a trend of increasing NO2 content in the stratosphere near the 10 mbar pressure level was detected. A photochemical-dynamical model is developed to account for the observed densities, which were also detected with ground-based instrumentation. The model calculations indicated that partitioning of the NO(x) family from N2O5 to NO2 was responsible for the trend. The new partitioning requires a lowering of the mixing ratio of NO(x), which was also observed. Finally, the SME data also confirmed that the enhanced NO2 concentrations were dependent on the solar zenith angle.

Zawodny, J. M.↗

NASA NTRS1986

Variation of the urban NO2 concentration during a ground inversion situation

In February 1985 the NO2 concentration over Goeteborg, a major Swedish city, was monitored during two inversion situations. The differential absorption technique was employed and the results show the build-up of the concentration. In this experiment the laser beam was scanned horizontally over Goeteborg. The results were presented as maps over the NO2 concentration distribution. For security reasons the beam was not parallel to the ground, which gives a height gradient in some measurements. During the measurement period the NO2 concentration variation build-up from the morning to the afternoon was monitored. Great concentration variations were seen. Later the mixing below the inversion layer, resulting in a more uniform, high concentration was seen. The breakdown of the inversion when stronger winds start was also seen. Comparisons with a traditional point-measuring chemiluminiscence instrument and an optical method DOAS (Differential Optical Absorption Spectroscopy), were made. The results are discussed. Strong spatial concentration variations are shown by the lidar measurements. For a point-measuring system, the instrument must be very carefully placed since its location will strongly influence the values it gives.

Sunesson, A.↗

NASA NTRS1987

An analysis of preliminary SAGE II data on ozone and NO2

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 percent is found for ozone and 20 percent 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.

Cunnold, D. M.↗

NASA NTRS1987

About a possible reference model for stratospheric NO2

After a brief review of observations of the global distribution of stratospheric NO2, the possibiliy of combining different data sets to construct a NO2 reference model is discussed. It is shown that difficulties mainly arise from the diversity of techniques and variability of NO2 in the stratosphere. The diurnal variation and possibly a long term trend present special problems.

Naudet, J. P.↗

NASA NTRS1988

Nighttime and daytime variation of atmospheric NO2 from ground-based infrared measurements

During the period of Feb. 28 to Mar. 2, 1986, 19 high resolution atmospheric spectra have been recorded during the night using the moon or during the day using the sun as a source with the Fourier transform spectrometer at the McMath Solar telescope on Kitt Peak. The NO2 absorption peak located at 2914.65/cm has been used to derive from the spectra the total vertical column densities of atmospheric NO2. A rather rapid decrease of the NO2 amount during the night has been observed, and its daytime increase from sunrise to sunset has been confirmed. A comparison with the predictions of a photochemical model is given.

Flaud, J.-M.↗

NASA NTRS1988

The equilibrium constant for N2O5 = NO2 + NO3 - Absolute determination by direct measurement from 243 to 397 K

Direct determinations of the equilibrium constant for the reaction N2O5 = NO2 + NO3 were carried out by measuring NO2, NO3, and N2O5 using long-path visible and infrared absorption spectroscopy as a function of temperature from 243 to 397 K. The first-order decay rate constant of N2O5 was experimentally measured as a function of temperature. These results are in turn used to derive a value for the rate coefficient for the NO-forming channel in the reaction of NO3 with NO2. The implications of the results for atmospheric chemistry, the thermodynamics of NO3, and for laboratory kinetics studies are discussed.

Cantrell, C. A.↗

NASA NTRS1990

Intercomparison of remote measurements of stratospheric NO and NO2

During the 1982 and 1983 Balloon Intercomparison Campaigns, the vertical profile of stratospheric NO2 was measured remotely by nine instruments and that of NO by two. Total overhead columns were measured by two more instruments. Between 30 and 35 km, where measurements overlapped, agreement between NO profiles was within + or - 30 percent, which is better than the accuracies claimed by the experimenters. Between 35 and 40 km, there was similarly good agreement between NO2 profiles, but below 30 km, differences of greater than a factor of 3 were found. In the second campaign, NO2 values from most instruments agreed within their quoted errors, except that the Oxford radiometer gave much lower values; the first campaign and the column measurements show a more uniform spread of results.

Roscoe, H. K.↗

NASA NTRS1991

Validation of SAGE II NO2 measurements

The validity of NO2 measurements from the stratospheric aerosol and gas experiment (SAGE) II is examined by comparing the data with climatological distributions of NO2 and by examining the consistency of the observations themselves. The precision at high altitudes is found to be 5 percent, which is also the case at specific low altitudes for certain latitudes where the mixing ratio is 4 ppbv, and the precision is 0.2 ppbv at low altitudes. The autocorrelation distance of the smoothed profile measurement noise is 3-5 km and 10 km for 1-km and 5-km smoothing, respectively. The SAGE II measurements agree with spectroscopic measurements to within 10 percent, and the SAGE measurements are about 20 percent smaller than average limb monitor measurements at the mixing ratio peak. SAGE I and SAGE II measurements are slightly different, but the difference is not attributed to changes in atmospheric NO2.

Cunnold, D. M.↗