Engineering topics

Bailey, P. L.

Publications and source records attributed to Bailey, P. L..

At least 19 records

NASA NTRS1994

Spectral signatures of polar stratospheric clouds and sulfate aerosol

Multiwavelength observations of Antarctic and midlatitude aerosol by the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment on the Upper Atmosphere Research Satellite (UARS) are used to demonstrate a technique that identifies the location of polar stratospheric clouds. The technique discussed uses the normalized area of the triangle formed by the aerosol extinctions at 925, 1257, and 1605/cm (10.8, 8.0, and 6.2 micrometers) to derive a spectral aerosol measure M of the aerosol spectrum. Mie calculations for spherical particles and T-matrix calculations for spheriodal particles are used to generate theoretical spectral extinction curves for sulfate and polar stratospheric cloud particles. The values of the spectral aerosol measure M for the sulfate and polar stratospheric cloud particles are shown to be different. Aerosol extinction data, corresponding to temperatures between 180 and 220 K at a pressure of 46 hPa (near 21-km altitude) for 18 August 1992, are used to demonstrate the technique. Thermodynamic calculations, based upon frost-point calculations and laboratory phase-equilibrium studies of nitric acid trihydrate, are used to predict the location of nitric acid trihydrate cloud particles.

Massie, S. T.↗

NASA NTRS1993

Revised reference model for nitric acid

A nearly global set of data on the nitric acid distribution was obtained for seven months by the Limb Infrared Monitor of the Stratosphere (LIMS) experiment on the Nimbus 7 spacecraft. The evaluation of the accuracy, precision, and resolution of these data is described, and a description of the major features of the nitric acid distributions is presented. The zonal mean for nitric acid is distributed in a stratospheric layer that peaks near 30 mb, with the largest mixing ratios occurring in polar regions, especially in winter.

Gille, J. C.↗

NASA NTRS1989

Revised reference model for nitric acid

Gille, J. C.↗

NASA NTRS1986

Inversion of limb radiance measurements - An operational algorithm

The limb radiance inversion radiometer (LRIR) and limb infrared monitor of the stratosphere (LIMS) experiments aboard the Nimbus 6 and 7 spacecraft have made observations of infrared emission by CO2, O3, H2O, HNO3, and NO2 at the earth's limb. This paper describes a method by which such measurements can be inverted to give vertical distributions of temperature and mixing ratios as functions of pressure. The simple and efficient approach was successfully applied to the LRIR data and subsequently in the initial assessment of the LIMS data. Inversion of synthetic data indicates the size of the errors to be expected as a result of the assumptions and instrumental errors. Retrievals of measured LIMS radiances are shown as examples and compared to in situ observations. The differences are comparable to those obtained with the more complex retrieval scheme used to process the LIMS archival products. Some problems are noted.

Bailey, P. L.↗

NASA NTRS1985

Transport of trace species deduced from LIMS observations

One of the critical problems in the middle atmosphere at this time is understanding the interaction between atmospheric motions and photochemistry, and the way in which these two processes maintain the distributions of photochemically active species such as ozone. Recent work has shown that a great deal can be learned by considering the zonally averaged distributions and transports, i.e., working in the latitude-altitude plane. This 2-dimensional approach has been used in the past in Eulerian formation. Recent work (DUNKERTON, 1978) has shown that formulating the transport problems in terms of the residual mean circulation, which has similarity to the Lagrangian mean motion, results in a more physical picture of the way in which the transport takes place. Here, data from the Limb Infrared Monitor of the Stratosphere (LIMB) experiment are used to investigate how well the residual mean formulation works with real data, in the sense of asking how well the predicted ozone changes match those in regions of the lower stratosphere in which chemical changes may be neglected. This allows a test of the approximations that are made, and of the strengths and weaknesses of this approach to transport calculation.

Gille, J. C.↗

NASA NTRS1985

Comparison of horizontal winds from the LIMS satellite instrument with rocket measurements

Statistical results are given for a comparison between horizontal geostrophic winds computed from satellite height data and all available in situ rocket wind soundings during a 7-month period. The satellite data are the daily mapped fields from the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) instrument, which extend from 100 to 0.1 mbar. Results indicate that in both the tropics and the extratropical Northern Hemisphere, the average zonal and meridional wind speeds agree to within 2-4 m/s throughout the stratosphere. The rms differences are much larger, with values of 5-10 m/s in the lower stratosphere, increasing to 20-40 m/s in the lower mesosphere. Time series show that LIMS and rocketsonde zonal wind speeds show coherent variations with temporal periods of 1-2 weeks and more, and both exhibit irregular variations on time scales of less than one week.

Smith, A. K.↗

NASA NTRS1984

A comparison of U.S. and USSR rocketsondes using LIMS satellite temperature sounding as a transfer standard

In connection with the reduction of the number of sounding rockets launched per year, there is a general need to make the most effective use of each sounding. In particular, it is often necessary to combine the results from different types of instruments to obtain a meaningful and complete picture of the atmosphere. For this reason, data from different rockets must be compatible. The present investigation is concerned with the utilization of the temperature soundings of the Limb Infrared Monitor of the Stratosphere (LIMS) as the uniform comparison standard. Gille et al. (1984) have compared the LIMS temperatures to a set of 122 U.S. datasonde rockets. In the current study, a comparison between soundings by rocketborne instruments of the USSR and LIMS is combined with the results of the previous LIMS-U.S. rocketsonde comparison in the same latitude bands to provide an updated estimate of the differences between U.S. and USSR rocketborne temperature measurements.

Gille, J. C.↗

NASA NTRS1984

Implications of the stratospheric water vapor distribution as determined from the Nimbus 7 LIMS experiment

The LIMS experiment on Nimbus 7 has provided new results on the stratospheric water vapor distribution. The data show (1) a latitudinal gradient with mixing ratios that increase by a factor of 2 from equator to + or - 60 degrees at 50 mb, (2) most of the time there is a fairly uniform mixing ratio of 5 ppmv at high latitudes, but more variation exists during winter, (3) a well-developed hygropause at low to midlatitudes of the lower stratosphere, (4) a source region of water vapor in the upper stratospehere to lower mesosphere that is consistent with methane oxidation chemistry, at least within the uncertainties of the data, (5) an apparent zonal mean H2O distribution that is consistent with the circulation proposed by Brewer in 1949, and (6) a zonal mean distribution in the lower stratosphere that is consistent with the idea of quasi-isentropic transport by eddies in the meridional direction. Limits to the use of the data in the refinement of our understanding of the stratospheric water vapor budget are noted.

Remsberg, E. E.↗

NASA NTRS1984

Validation of nitrogen dioxide results measured by the limb infrared monitor of the stratosphere (LIMS) experiment on NIMBUS 7

The validation of results from the nitrogen dioxide channel and the quality of the data are examined in connection with the LIMS experiment which ran from late October 1978 to late May 1979. Factors studied include: channel characteristics, experiment errors due to instrument and spacecraft effects, predicted and measured precision, predicted accuracy, and comparisons with correlative measurements made in a series of balloon underflights. Features such as profile shape and slope of the mixing ratio altitude distribution are in good agreement. The LIMS data also fall within the range of previous mixing ratio measurements and are consistent with model estimates. The calculated on-orbit precision is about 0.3 ppbv and the estimated accuracy from simulations is about 2 ppbv over the 3-10-mbar range. Accuracy is less at higher and lower pressure levels. These results provide the first day-night set of nitrogen dioxide measurements from space.

Russell, J. M., III↗

NASA NTRS1984

Validation of water vapor results measured by the Limb Infrared Monitor of the Stratosphere experiment on Nimbus 7

In the LIMS experiment using thermal IR limb scanning to sound the composition and structure of the upper atmosphere, one of the LIMS channels was spectrally centered at 6.9 micrometers to measure the vertical profile and global distribution of stratospheric water vapor. This channel's characteristics, the data from it, and the steps taken to validate results are described. The mean difference between the LIMS measurements and data from 13 balloon underflights is about 0.6 ppmv with LIMS mixing ratios biased high; this difference is of about the same order as estimated LIMS accuracy and less than the sum of the errors for LIMS and the balloon techniques. In-orbit precision is 0.2-0.3 ppmv and accuracy is estimated at 20-30 percent from 50 mbar to the stratopause. An unexplained diurnal variation exists in the vertical profile data which is largest at the 1-mbar level and virtually nonexistent at 10 mbar; day values are higher than night. More confidence is placed in zonal mean distributions averaged over several days than in single profiles. A zonal mean pressure-latitude cross section is described for January 5-9, 1979.

Russell, J. M., III↗

NASA NTRS1984

Spectroscopy and transmittances for the LIMS experiment

The Limb Infrared Monitor of the Stratosphere (LIMS) instrument on the Nimbus 7 spacecraft sensed limb emission profiles for 7 months, starting in October 1979. Vertical temperature profiles are inferred from measurements in two CO2 channels, and constituent profiles are obtained form the O3, HNO3, NO2, and water vapor channels. The line parameters used to calculate transmittances in the retrieval algorithm are presented. Their adequacy for LIMS and for other applications are assessed, and recommendations for future investigations are outlined.

Drayson, S. R.↗

NASA NTRS1984

Validation of temperature retrievals obtained by the Limb Infrared Monitor of the Stratosphere (LIMS) experiment on Nimbus 7

An outline is given of LIMS temperature determinations (as a function of pressure) from measurements in two channels covering portions of the 15-micrometer band of carbon dioxide. The known sources of error from the radiometer and data reduction are used to estimate the systematic and random errors expected of the results. Observational determinations of the complete end-to-end precision are obtained by computing the standard deviation of six sequential temperature retrievals in regions where the atmosphere is horizontally uniform. This yields values of 0.2 to 0.6 K, in reasonable agreement with the estimates. A correction for horizontal gradients in the atmosphere leads to a large reduction in the differences between the stratospheric temperatures determined on the ascending and descending portions of the orbit. The temperatures agree in the mean with radiosondes and rocketsondes to within 1-2 K in most regions below 1 mbar. Several interesting, previously unseen features included cold regions in the mid-latitude mesosphere and wavelike vertical variations in the tropics.

Gille, J. C.↗

NASA NTRS1984

The validation of Nimbus 7 LIMS measurements of ozone

Approximately seven and one half months of stratospheric ozone profiles have been processed from the LIMS (Limb Infrared Monitor of the Stratosphere) experiment on the Nimbus 7 satellite. Data profiles cover the stratosphere and mesosphere from 100 to 0.1 mbar and from 84 degrees N to 64 degrees S latitude. Topics covered include the ozone channel characteristics, precision, systematic uncertainties, and comparisons with data from balloon and rocket underflights, Umkehr soundings, and Dobson measurements. Comparisons with Dobson total ozone are made by integrating combined LIMS plus balloon profiles. The estimated on-orbit precision is 0.02-0.16 ppmv. Simulations of the experiment indicate potential systematic uncertainties ranging from 15 percent in the 1-mbar region to an upper limit of 40 percent at 100 mbar and 0.1 mbar. Results are well within the uncertainties for the correlative sensors themselves. LIMS detects significant vertical structure in the ozone profile even below the ozone mixing ratio peak. Several other comparisons showing good agreement are noted.

Remsberg, E. E.↗

NASA NTRS1984

Accuracy and precision of the nitric acid concentrations determined by the limb infrared monitor of the stratosphere experiment on NIMBUS 7

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Gille, J. C.↗

NASA NTRS1984

Evidence for equatorial Kelvin modes in Nimbus-7 LIMS

Equatorial Kelvin waves have emerged as an important source of westerly momentum for the tropical stratosphere. The present investigation is concerned with an analysis of remotely derived temperatures from Nimbus-7 LIMS (Limb Infrared Monitor of the Stratosphere). It is found that eastward propagating disturbances are present in two independent LIMS data sets. The disturbances manifest themselves consistently at several levels throughout the stratosphere and account for much of the tropical temperature variance out to latitudes where extratropical signals become large. Compelling evidence is found for several distinct phase velocities. Spectral analysis indicates isolated eastward variance at principally two frequencies for both wavenumbers.

Salby, M. L.↗

NASA NTRS1982

Infrared limb scanning in the presence of horizontal temperature gradients - An operational approach

Simulation and analysis of IR limb radiance obtained by a satellite-borne IR limb scanner have demonstrated that horizontal temperature gradients in the atmosphere play an important role in limiting the accuracy of retrieved temperature and constituents below approximately 25 km. A simple operational approach to converting these observed radiances to equivalent spherical radiances is developed which preserves the advantages of the sphericity assumption in the inversion process.

Roewe, D. A.↗

NASA NTRS1982

Results from the LIMS experiment for the PMP-1 winter 1978/79

The results of a preliminary analysis of the data on the global distributions of temperature and trace constituents in the middle atmosphere (15-65 km) obtained with the limb IR monitor (LIMS) are presented. The 6-channel limb-scanning radiometer was sensitive to the 15 micron bands of CO2, as well as other wavelengths, and was launched on the Nimbus 7 satellite in 1978. The derived data were partially compared with Soviet rocketsonde data to track an evolution in a warming trend over Siberia. The morphology of the changes were attributed to stratospheric warming. The comparisons with rocketsonde data indicated that the LIMS data were suitable for the determination of planetary wave amplitudes and phases, heat and momentum transport, and Eliassen-Palm fluxes.

Gille, J. C.↗

NASA NTRS1982

The variability of stratospheric nitrogen compounds observed by LIMS in the winter of 1978-1979

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 deg S to 84 deg N. Two of the gases, NO2 and HNO3, are important elements in the NO(x) chain of chemical reactions leading to ozone destruction. Results for these gases are described in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January-May 1979, when a major stratospheric warming occurred.

Russell, J. M., III↗