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Scientific Objectives: The Stratospheric Aerosol and Gas Experiment I instrument, a Sun photometer, aboard the Applications Explorer Mission-2 (AEM-2) satellite began collecting data in October 1979. The scientific objective was to develop a global stratospheric aerosol, ozone, and nitrogen dioxide database that could be used for the investigation of the spatial and temporal variations of these species caused by seasonal and short-term meteorological variations, atmospheric chemistry, microphysics, and transient phenomena such as volcanic eruptions. The database could also be used for the study of trends, atmospheric dynamics and transport, and potential climatic effects. The SAGE I sensor was designed to measure the attenuation of solar radiation resulting from atmospheric aerosol, ozone, and nitrogen dioxide at four spectral regions through the Earth's atmosphere during each spacecraft sunrise and sunset. Project Description: The AEM-2 satellite was placed in an orbit of approximately 600 kilometers at an inclination of 56 degrees to extend the latitudinal coverage for the solar occultation measurements from 79 degrees South to 79 degrees North. The SAGE I instrument consists of four spectral channels centered at wavelengths of 1000, 600, 450, and 385 nanometers for measuring global data concerning aerosol vertical extinction profiles, ozone vertical concentrations profiles, and nitrogen dioxide vertical concentrations profiles during spacecraft sunrise and sunset. The solar wavelengths of 1000 and 450 nanometers are used to generate altitude profiles of ozone and nitrogen dioxide concentration. The SAGE I aerosol data were validated by comparison with correlative lidar and dustsonde in situ measurements, the ozone data were validated by comparison with balloon ECC ozonesonde and rocket measurements, and the nitrogen dioxide measurements were compared with climatology. The operation of the instrument, during each sunrise and sunset measurement, was totally automatic. Prior to each sunrise or sunset, the instrument was rotated in azimuth to its predicted solar acquisition position. When the Sun entered the instrument's field of view, the instrument adjusted its azimuth position to lock onto the radiometric center of the Sun to within +/- 45 arcsec and then acquired the sun by rotating its scan mirror to the proper elevation angle. As the Sun traversed between the horizon and the tangent height of 150 kilometers, radiometric channel data were sampled at a rate of 64 samples per second per channel, digitized to 12-bit resolution, and recorded for later transmission back to Earth. Additional SAGE I instrument information can be found in McCormick et al (1979). The SAGE I instrument collected data for almost three years until the AEM-2 satellite power subsystem failed. Data Used and Produced: The SAGE I science and engineering data, along with spacecraft time, position, and housekeeping data, were stored aboard the spacecraft and then down linked to NASA GSFC through a ground station. GSFC then forwarded these data to LaRC for processing and scientific analysis. GSFC also sent spacecraft and solar ephemeris data to LaRC on separate weekly tapes. LaRC combines three data sources to produce the SAGE I MERDAT: (1) the SAGE I instrument data, (2) the spacecraft and solar ephemeris data, and (3) NOAA NMC temperature and density interpolations from the standard NMC spatial gridded analyses at the 18 standard pressure levels and at the tropopause for each tangent event location. The MERDAT files are used as the data input to the inversion process. At the completion of the data processing, three Level 2 SAGE I products are produced: aerosol extinction profiles, ozone concentration profiles, and nitrogen dioxide concentration profiles. The SAGE1_AERO_PRF_NAT data set contains three years of aerosol extinction profiles data. Each granule consists of three months of data (seasonal data) which is in the SAGE I's native binary format. The data coverage begins February 1979 and extends through November 1981. Data are stored in event format. Each measurement event consists of 48 parameters (does not include spares). The SAGE1_AERO_PRF data set contains three years of aerosol extinction profiles data. Each granule consists of one month of data. These data are in Hiearchical Data Format (HDF). The data coverage begins February 1979 and extends through November 1981. Data are stored in parameter format. Each measurement event consists of 38 parameters. The Ozone Concentration Profiles data set is not currently available at the Langley DAAC. It will be archived in Hierarchical Data Format (HDF). The Nitrogen Dioxide Concentration Profiles data set is not currently available at the Langley DAAC. It will be archived in Hierarchical Data Format (HDF). Project Archive Contact: Langley DAAC User Services Office Mail Stop 157D NASA Langley Research Center Hampton, VA 23681-0001 USA Phone: (804) 864-8656 FAX: (804) 864-8807 INTERNET > larc@eos.nasa.gov WWW Home Page: "http://eosweb.larc.nasa.gov/" Project Manager Contact: M. Patrick McCormick Mail Stop 475 NASA Langley Research Center Hampton, VA 23681-0001 USA Phone: (804) 864-2669 FAX: (804) 864-2671 INTERNET > M.P.MCCORMICK@LaRC.NASA.GOV Michael W. Rowland SAIC Mail Stop 475 Hampton, VA 23681-0001 USA Phone: (804) 864-2691 FAX: (804) 864-2671 INTERNET > M.W.ROWLAND@LaRC.NASA.GOV References: The following list of references is provided as a starting point for someone wishing to learn more about the SAGE I instrument, inversion method, validation studies and recent scientific studies. Chandra, S.; McPeters, R. D.; Hudson, R. D.; and Planet, W. 1990: Ozone Measurements From the NOAA-9 and the Nimbus-7 Satellites: Implications of Short and Long Term Variabilities. Geophys. Res. Lett., vol. 17, no. 10, pp. 1573-1576. Chu, W. P.; and McCormick, M. P. 1979: Inversion of Stratospheric Aerosol and Gaseous Constituents From Spacecraft Solar Extinction Data in the 0.38-1.0 micrometer Wavelength Region. Appl. Opt., vol. 18, no. 9, pp. 1404-1413. Chu, W. P.; and McCormick, M. P. 1986: SAGE Observations of Stratospheric Nitrogen Dioxide. J. Geophys. Res., vol. 91, no. D5, pp. 5465-5476. Chu, W. P.; McCormick, M. P.; Lenoble, J.; Brogniez, C.; and Pruvost, P. 1989: SAGE II Inversion Algorithm. J. Geophys. Res., vol. 94, no. D6, pp. 8339-8351. Cunnold, D. M.; Zawodny, J. M.; Chu, W. P.; Pommereau, J. P.; and Goutail, F. 1991: Validation of SAGE II NO2 Measurements. J. Geophys. Res., vol. 96, pp. 12,913-12,925. Geller, Marvin A.; Wu, Mao-Fou; and Gelman, Melvyn E. 1983: Tropospheric-Stratosphere (Surface-55 km) Monthly Winter General Circulation Statistics for the Northern Hemisphere--Four Year Averages. J. Atmos. Sci., vol. 40, no. 5, pp. 1334-1352. Gelman, M. E.; Miller, A. J.; Johnson, K. W.; and Nagatani, R. M. 1986: Detection of Long-Term Trends in Global Stratospheric Temperatures From NMC Analyses Derived From NOAA Satellite Data. Adv. Space Res., vol. 6, no. 10, pp. 17-26. Herman, J. R.; Hudson, R. D.; and Serafino, G. 1990: Analysis of the Eight-Year Trend in Ozone Depletion From Empirical Models of Solar Backscattered Ultraviolet Instrument Degradation. J. Geophys. Res., vol. 95, no. D6, pp. 7703-7416. Kent, G. S.; and McCormick, M. P. 1984: SAGE and SAM II Measurements of Global Stratospheric Aerosol Optical Depth and Mass Loading. J. Geophys. Res., vol. 89, no. D4, pp. 5303-5314. Kent, G. S.; Farrukh, U. O.; Wang, P. H.; and Deepak, A. 1988: SAGE I and SAM II Measurements of 1 micrometer Aerosool Extinction in the Free Troposphere. J. Appl. Meteorol., vol. 27, pp. 269-279. Kerr, J. B.; Evans, W. F. J.; and McConnell, J. C. 1977: The Effects of NO2 Changes at Twilight on Tangent Ray NO2 Measurements. Geophys. Res. Lett., vol. 4, no. 12, pp. 577-579. Lenoble, J.; and Pruvost, P. 1983: Inference of the Aerosol Angstrom Coefficient From SAGE Short-Wavelength Data. J. Clim. & Appl. Meteorol., vol. 22, no. 10, pp. 1717-1725. McCormick, M. P.; Hamill, Patrick; Pepin, T. J.; Chu, W. P.; Swissler, T. J.; and McMaster, L. R. 1979: Satellite Studies of the Stratospheric Aerosol. Bull. American Meteorol. Soc., vol. 60, no. 9, pp. 1038-1046. McCormick, M. Patrick; Kent, G. S.; Yue, G. K.; and Cunnold, D. M. 1982: Stratospheric Aerosol Effects From Soufriere Volcano as Measured by the SAGE Satellite System. Science, vol. 216, no. 4550, pp. 1115-1118. McCormick, M. P.; Swissler, T. J.; Hilsenrath, E.; Krueger, A. J.; and Osborn, M. T. 1984: Satellite and Correlative Measurements of Stratospheric Ozone: Comparison of Measurements Made by SAGE, ECC Balloons, Chemiluminescent, and Optical Rocketsondes. J. Geophys. Res., vol. 89, no. D4, pp. 5315-5320. McCormick, M. P.; Veiga, R. E.; and Zawodny, J. M. 1989: Comparison of SAGE I and SAGE II Stratospheric Ozone Measurements. Ozone in the Atmosphere -- Proceedings of the Quadrennial Ozone Symposium 1988 and Tropospheric Ozone Workshop, Rumen D. Bojkov and Peter Fabian, eds., A Deepak Publishing, pp. 202-205. McMaster, Leonard R. 1986: Stratospheric Aerosol and Gas Experiment (SAGE II). Sixth Conference on Atmospheric Radiation, American Meteorological Soc., pp. J46-J48. Reiter, R.; and McCormick, M. P. 1982: SAGE - European Ozonesonde Comparison. Nature, vol. 300, no. 5890, pp. 337-339. Russell, P. B.; and McCormick, M. P.; Swissler, T. J.; Chu, W. P.; Livingston, J. M.; Fuller, W. H., Jr.; Rosen, J. M.; Hofmann, D. J.; McMaster, L. R.; Woods, D. C.; and Pepin, T. J. 1981: Satellite and Correlative Measurements of the Stratospheric Aerosol. II: Comparison of Measurements Made by SAM II, Dustsondes and an Airborne Lidar. J. Atmos. Sci., vol. 38, no. 6, pp. 1295-1312. Russell, P. B.; and McCormick, M. P.; Chu, W. P.; Livingston, J. M.; Pepin, T. J. 1981 Satellite and Correlative Measurements of the Stratospheric Aerosol. I: An Optical Model for Data Conversions. J. Atmos. Sci., vol. 38, no. 6, pp. 1279-1294. Russell, P. B.; and McCormick, M. P.; Swissler, T. J.; Rosen, J. M.; Hofmann, D. J.; and McMaster, L. R. 1984: Satellite and Correlative Measurements of the Stratospheric Aerosol. III: Comparison of Measurements by SAM II, SAGE, Dustsondes, Filters, Impactors, and Lidar. J. Atmos. Sci., vol. 41, no. 11, pp. 1791-1800. Wang, Pi-Huan; McCormick, M. P.; and Chu, W. P. 1983: A Study on the Planetary Wave Transport of Ozone During the Late February 1979 Stratospheric Warming Using the SAGE Ozone Observation and Meteorological Information. J. Atmos. Sci., vol. 40, no. 10, pp. 2419-2431. Wang, Pi-Huan; and McCormick, M. P. 1985: Variations in Stratospheric Aerosol Optical Depth During Northern Warmings. J. Geophys. Res., vol. 90, no. D6, pp. 10,597-10,606. Watson, R. T. et al. 1988: Present State of Knowledge of the Upper Atmosphere 1988: An Assessment Report. NASA RP-1208. WMO Global Ozone Research and Monitoring Project 1981: The Stratosphere 1981--Theory and Measurements. NASA TM-84125. (Available as WMO Rep. No. 11.) WMO Global Ozone Research and Monitoring Proj. 1990: Scientific Assessment of Stratospheric Ozone: 1989, Volume I. Rep. No. 20, World Meteorological Organization. Woodbury, Gerard E.; and McCormick, M. P. 1986: Zonal and Geographical Distributions of Cirrus Clouds Determined From SAGE Data. J. Geophys. Res., vol. 91, no. D2, pp. 2775-2785. Yue, Glenn K.; and Deepak, Adarsh 1983: Retrieval of Stratospheric Aerosol Size Distribution From Atmospheric Extinction of Solar Radiation at Two Wavelengths. Appl. Opt., vol. 22, no. 11, pp. 1639-1645. Yue, Glenn K.; and Deepak, Adarsh 1984: Latitudinal and Altitudinal Variation of Size Distribution of Stratospheric Aerosols Inferred From SAGE Aerosol Extinction Coefficient Measurements at Two Wavelengths. Geophys. Res. Lett., vol. 11, no. 10, pp. 999-1002. Yue, Glenn K.; McCormick, M. P.; and Chu, W. P. 1984: A Comparative Study of Aerosol Extinction Measurements Made by the SAM II and SAGE Satellite Experiments. J. Geophys. Res., vol. 89, no. D4, pp. 5321-5327.
SAGE I