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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

SAGE studies of the waves and eddy fluxes of ozone and temperature near 55 deg during the late February 1979 stratospheric warming

Ozone data from the Stratospheric Aerosol and Gas Experiment have been used in conjunction with meteorological information to study the waves and eddy fluxes of ozone and temperature near 55 deg N during the late February 1979 stratospheric warming. The results indicate an intense poleward eddy ozone transport in the altitude range between approximately 24 and 38 km, and an equatorward transport above an altitude of about 38 km. It is found that this equatorward eddy ozone transport in the upper stratosphere was accompanied by a poleward eddy heat transport, as expected on the basis of the ozone photochemistry. The results also indicate that the phase relationship between ozone and temperature waves agrees qualitatively with existing model analyses.

Wang, P.-H.↗
NASA NTRS1986

Support of validation of SAGE 2 data

An error analysis of differential absorption lidar (DIAL) measurements of stratospheric ozone from a Space Shuttle is discussed. A transmitter system consisting of a KrF excimer laser pumping gas cells of H2 or D2 producing output wavelengths in the near UV is shown to be useful for the measurement of ozone in an altitude range from 15 to 50 km.

Copeland, Gary E.↗
NASA NTRS1988

Antarctic measurements of ozone by SAGE II in the spring of 1985, 1986, and 1987

This paper presents a three-year (1985, 1986, and 1987) comparison of ozone profiles within the southern polar vortex for September and October, using data obtained by the Stratospheric Aerosol and Gas Experiment II. It was found that, by the first half of October 1986, daily minima in total ozone showed a moderate recovery of 5-7 percent relative to 1985, whereas in 1987, a significant drop of 15 percent from the 1985 minima was observed. The interannual variability of total ozone, temperature, and temperature area or vortex size were found to display a quasi-biennial oscillation (QBO) signal similar to that established by Garcia and Solomon (1987) for Antarctica. Since the 1985 and 1987 years displayed the same QBO phase (westerly) and the 1987 depletion was greater than that of 1985, it is concluded that the long-term secular ozone trend continues to be downward.

Mccormick, M. P.↗
NASA NTRS1988

Antarctic measurements of ozone, water vapor, and aerosol extinction by Sage 2 in the spring of 1987

Recent measurements of ozone, water vapor, and aerosol extinction from the spring of 1987 are presented and compared to 1985 and 1986. The observed changes to variations in meteorological conditions in the vortex for these three years are noted. March ozone data at similar latitudes for these three years will be used to investigate coupling between severity of the springtime depletion and early fall values. Researchers also investigate correlations between the measured species of water vapor, ozone, and aerosols throughout the vortex region.

Larsen, J. C.↗
NASA NTRS1989

SAGE II inversion algorithm

The operational Stratospheric Aerosol and Gas Experiment II multichannel data inversion algorithm is described. Aerosol and ozone retrievals obtained with the algorithm are discussed. The algorithm is compared to an independently developed algorithm (Lenoble, 1989), showing that the inverted aerosol and ozone profiles from the two algorithms are similar within their respective uncertainties.

Chu, W. P.↗
NASA NTRS1991

Comparison of aerosol extinction profiles from lidar and SAGE II data at a tropical station

Aerosol extinction profiles obtained from lidar data at Trivandrum (8.6 deg N, 77 deg E) are compared with corresponding Stratospheric Aerosol and Gas Experiment II extinction profiles. The agreement between the two is found to be satisfactory. The extinction profiles obtained by both the experiments showed a prominent peak at 23-24 km altitude in the stratosphere. The study revealed large variability in upper tropospheric extinction with location (latitude).

Parameswaran, K.↗
NASA NTRS1990

Global distributions of cirrus determined from Sage II occultation measurements between November 1984 and October 1988

This paper describes the morning versus late afternoon differences and the seasonal changes of zonal average cirrus occurrence, and presents an overview of the global distributions of cirrus clouds for both summer and winter months. Results are compared with the corresponding results in the literature to illustrate the complementary nature of these cirrus cloud climatology efforts utilizing various data sets.

Chiou, E. W.↗
NASA NTRS2001

Participation of HNO3 CIMS Instrument in the Sage III Ozone Loss and Validation Experiment (SOLVE)

This project was part of a larger SOLVE project led by Paul Wennberg at California Institute of Technology. The work completed on this project included participating in the installation and preflight testing of a new chemical ionization mass spectrometer for measuring gas and particle phase nitric acid on the ER-2. The investigators subsequently participated in SOLVE where additional instrument improvements were made and a substantial data set was generated. The two Georgia Tech investigators that participated in this work (Fred Eisele and Dave Tanner) had previously been responsible for much of the design and construction of the ion source and mass spectrometer which would be used to measure HNO3 in SOLVE, with Caltech focusing on inlets, calibration, gas supplies/pumping computer control, and overall integration. Thus, a similar focus remained during the SOLVE measurements though all investigators worked on most if not all aspects of the instrument at some point in the mission. Some of the more interesting results from the study included measurements of nitric acid on what are thought to be 5-20 microns diameter individual particles which could supply a local mechanism for HNO3 removal, Nitric acid measurements on SOLVE were completed as a collaborative effort with a great deal of overlap between this project and the larger parent project led by Paul Wennberg. As such, the instrumentation used, its operation, and the resulting measurements are far more fully discussed in the attached report (appendix A) which describes the joint SOLVE nitric acid measurement effort.

Eisele, F. L.↗
NASA NTRS2006

Sage Simulation Model for Technology Demonstration Convertor by a Step-by-Step Approach

The development of a Stirling model using the 1-D Saga design code was completed using a step-by-step approach. This is a method of gradually increasing the complexity of the Saga model while observing the energy balance and energy losses at each step of the development. This step-by-step model development and energy-flow analysis can clarify where the losses occur, their impact, and suggest possible opportunities for design improvement.

Demko, Rikako↗
NASA NTRS2005

The Venus SAGE Atmospheric Structure Investigation

Experiment goals and objectives are: a) To accurately define the state properties as a function of altitude from below the 10(exp -4) mb level (approx.150 km) to 92 bars (surface); b) To measure the stability of the atmosphere, and identify convective layers and stable layers, where they exist; c) To detect cloud levels from changes in the lapse rate at their boundaries; d) To provide state properties within the cloud levels, and thus provide supplementary information on cloud composition; e) To search for and characterize wave structure within the atmosphere; f) To search for and measure the intensity and scale of turbulence; g) To measure descent and surface wind speed and direction; h) To provide Lander altitude and attitude during decent for descent imaging analysis; and i) To provide a back-up landing sensor.

Colaprete, Anthony↗
NASA NTRS2012

Toward a Combined SAGE II-HALOE Aerosol Climatology: An Evaluation of HALOE Version 19 Stratospheric Aerosol Extinction Coefficient Observations

Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 microns is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 microns is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 micron aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40micronaerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 micron channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

Thomason, L. W.↗