Upper Atmosphere Research Satellite

Muller, R., P. J. Crutzen, J.-U. GrooB, C. Briihl, J. M. Russell III, and A. F. Tuck, Chlorine Activation and Ozone Depletion in the Arctic Vortex Observations by the Halogen Occultation Experiment on the Upper Atmosphere Research Satellite, J. Geophys. Res., 101, 12531-12554 (1996). 

The Jet Propulsion Laboratory (JPL) research team have successfully flown the Microwave Limb Sounder (MLS) aboard the Upper Atmospheric Research Satellite (UARS), which has been measuring stratospheric profiles of CIO, O3, H20 and HN03 since 1992 (Waters et al., 1993) (Table 1). In total some 140 publications have been published on the basis of MLS data. The Microwave Atmospheric Sounder (MAS) flew three times aboard the Shuttle also measuring CIO, 03 and H20 and has also provided a unique set of observations (Hartmann et al., 1996). 

Since its launch in 1991 the Upper Atmospheric Research Satellite (UARS) has circled the Earth in a low earth non sun-synchronous orbit. The UARS flew three infrared experiments. In addition to ISAMS (described above) the Cryogenic Limb Array Etalon Spectrometer (CLAES) and the Halogen Occultation Experiment (HALOE) make infrared measurements designed to yield information about stratospheric and tropospheric trace constituents. 

Barnett, J.J., P.E. Morris, T.J. Nightingale, C.W.P. Palmer, G.D. Peskett, C.D. Rodgers, F.W. Taylor, P. Venters, R.J. Wells, J.G. Whitney, J. Ballard and J. Knight (1992) The Improved Stratospheric and Mesospheric Sounder on the Upper Atmosphere Research Satellite. Society of Photo-Optical Instrumentation and Engineering Proceedings 1715 527. 

Roche, A.E., P.B Fomey, J.B. Kumer, L.G. Naes and T.C. Nast (1982) Performance analysis for the cryogenic etalon spectrometer on the upper atmospheric research satellite. Society of Photo-Optical Instrumentation and Engineering Proceedings 3S4. 46-S4. 

UARS (1987) Upper Atmosphere Research Satellite Project Data Book April 1987. Prepared by General Electric Astro-Space Division Valley Forge for the NASA Goddard Space Flight Center. 

Waters, J.W, L. Froideveaux, W.G. Read, G.L. Manney, L.S. Elson, D.A. Flower, R.F. Jamot and R.S. Harwood (1993) Stratospheric CIO and ozone from the microwave limb sounder on the Upper Atmospheric Research Satellite. Nature 362 597-602. 

By September 1992, this ozone hole was nearly three times the area of the United States. In December 1994, three years of data from NASA s Upper Atmosphere Research Satellite (UARS) provided conclusive evidence that CECs are primarily responsible for this destruction of the ozone layer. Considerable thinning of the ozone layer in the Northern Hemisphere has also been observed. 

One of the most important atmospheric dynamical quantities is the zonal wind (wind speed in the longitudinal direction). Wind velocities are conventionally positive for eastward winds (also called westerlies) and negative for westward winds (easterlies). They are mostly derived from the observed thermal structure of the atmosphere, although local values can be provided by radiosonde and radar measurements. To date, very few attempts have been made to directly measure the atmospheric wind components from space. The High Resolution Doppler Imager (HRDI) on board the Upper Atmosphere Research Satellite (UARS) has provided information on horizontal winds in the mesosphere/lower thermosphere (50-115 km) and in the stratosphere (10-40 km) by observing the Doppler shifts in the emission lines of an O2 atmospheric... 

Figure 3.32. Zonally averaged temperature in the vicinity of the mesopause (65 to 105 km) observed in July by the HRDI instrument on board the Upper Atmosphere Research Satellite (UARS). From Ortland et al, 1997.

Hays, P.B., V.J. Abreu, M.E. Dobbs, D.A. Gell, H.J. Grassl, and W.R. Skinner, The high-resolution Doppler imager on the Upper Atmosphere Research Satellite. J Geophys Res 98, 10,713, 1993. 

Upper Atmosphere Research Satellite (UARS) (see e.g., Woods et al, 1996 1998). 

The meridional distribution of the heating rate due to O2 and O3, shown in Figure 4.25, is based on observations by the Upper Atmosphere Research Satellite (UARS) during the period November 19-December 19, 1991 (Mlynczak et al, 1999). The corresponding values are determined by an expression of the form (4.10), he.,... 

Two-dimensional distributions of the radiative cooling rate can be obtained when similar calculations are repeated for different latitudes and seasons. Figure 4.27a shows, for example, the meridional distribution of the 15 m CO2 cooling calculated by Mlynczak et al. (1999) between 100 and 0.1 hPa, on the basis of measurements by the Upper Atmosphere Research Satellite (UARS) for the period of November 19-December 19, 1991. A precise calculation must include the contribution of different isotopes of CO2, even those which constitute only 1.5% of the atmospheric abundance of this species. The effect of the fundamental and hot bands of these isotopes is large in the mesosphere and upper stratosphere, where a corresponding cooling rate of about 2 K/day is calculated (Williams and Rodgers, 1972). 

Figure 5.10. Zonally averaged ozone mixing ratio (ppmv) in the stratosphere (15-55 km) in January. Climatological values derived from observations by the Halogen Occultation Experiment (HALOE) and the Microwave Limb Sounder (MLS) on board the Upper Atmosphere Research Satellite (UARS). (Courtesy of W. Randel, NCAR).

Upper stratospheric and mesospheric water vapor has been measured by microwave techniques, both from the ground (e.g., Gibbins et al., 1981 Deguchi and Muhleman, 1982 Bevilacqua et al, 1983) and from aircraft (Waters et al., 1980). Measurements by the HALOE instrument on board the Upper Atmosphere Research Satellite (UARS see Russell et al, 1993 Summers et al, 1997 and Figure 5.22) show that the water vapor mixing ratio in the mesosphere is of the order of 6 ppmv up to 70 km, and that it decreases to values less than 4 ppmv near 75 km. The presence of a local maximum of more than 7.5 ppmv in the tropics detected by the HALOE instrument between 65 and 68 km (Summers et al., 1997) is not understood. If confirmed by independent... 

Dessler, A.E., M.D. Burrage, J.-U. Groofi, J.R. Holton, J.L. Lean, S.T. Massie, M.R. Schoeberl, A.R. Bouglass, and C.H. Jackman, Selected science highhghts from the first 5 years of the Upper Atmosphere Research Satellite (UARS) Program. Rev Geophys 36, 183, 1998. 

FIGURE 5 Monthly mean, zonal-mean temperature distributions observed by the Upper Atmosphere Research Satellite (UARS) (panels a, c) and calculated net zonal-mean heating rates (panels b, d). [Courtesy of M. G. Mlynczak, NASA/Langley Research Center.]... 

Figure 13 shows the zonal-mean meridional circulation during Northern Hemisphere winter and summer calculated from the net heating rate. The latter was in turn obtained from observations of temperature and ozone made by the Upper Atmosphere Research Satellite (UARS). In the lower stratosphere, the mean meridional circulation is upward in the tropics and downward in extratropical latitudes throughout the year (this is the Brewer-Dobson circulation mentioned earlier). Above about 30 mb (25 km), the circulation exhibits a single-cell structure, directed mainly from the summer to the winter hemisphere. 

Some of the unmanned satellites primarily dedicated to UV solar or celestial astronomy include the Solar Maximum Mission (SMM), the International Ultraviolet Explorer (lUE), the Extreme Ultraviolet Explorer (EUVE), the Far Ultraviolet Spectroscopic Explorer (FUSE), and the Solar Heliospheric Observatory (SOHO). Ultraviolet studies of the sun are also a significant part of the Upper Atmospheric Research Satellite (UARS) mission, andUV astronomy is an important part of the operations of the Hubble Space Telescope. 

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