Near-IR Spectrophotometry of Jovian Aerosols—Meridional and Vertical Distributions☆

Abstract Photometrically calibrated grism spectra of Jupiter in the H (1.45–1.8 μm) and K (1.95–2.5 μm) bands with a resolution of about 100 were taken with the 5-m Hale telescope at Palomar in August of 1995. The spectra were obtained as meridional cuts at six different longitudes on the planet, with one cut crossing the Great Red Spot. The technique outlined in D. Banfield et al. (1996, Icarus 121, 389–410) for the retrieval of scatterer density with altitude from near-infrared spectra is used and refined. It is expected that this retrieval technique will find use in the interpretation of many atmospheric near-infrared reflection spectra, especially those from Galileo NIMS and Cassini VIMS. For the wavelengths and spectral resolution used in this study, the sensitivity of the inversions extends from pressure levels near 400 mbar up to about 20 mbar. Employing this inversion technique on the spectra yields well-resolved jovian cloud densities for τ ≲ 0.1, as a function of latitude and altitude. The density of scatterers is minimum at a height where the pressure is about 100 mbar and increases both upward and downward from this level. The minimum near 100 mbar can be explained by coagulation of settling particles, leading to an increase in fall speed. The results indicate that stratospheric haze particles are generated at heights where p ≲ 20 mbar.

[1]  JOHN S. Lewis,et al.  Atmospheric and cloud structures of the Jovian planets , 1973 .

[2]  Recent multispectral observations of Jupiter from 0.6 to 2.4 microns , 1993 .

[3]  S. Calcutt,et al.  Calculated k distribution coefficients for hydrogen‐ and self‐broadened methane in the range 2000–9500 cm−1 from exponential sum fitting to band‐modelled spectra , 1996 .

[4]  Z. Kam,et al.  Absorption and Scattering of Light by Small Particles , 1998 .

[5]  D. Strobel,et al.  HCN formation on Jupiter: The coupled photochemistry of ammonia and acetylene , 1983 .

[6]  R. West,et al.  Quasi-random narrow-band model fits to near-infrared low-temperature laboratory methane spectra and derived exponential-sum absorption coefficients , 1993 .

[7]  C. Hord,et al.  A study of photopolarimeter system UV absorption data on Jupiter, Saturn, Uranus, and Neptune: Implications for auroral haze formation , 1991 .

[8]  R. West,et al.  Impact debris particles in Jupiter's stratosphere , 1995, Science.

[9]  P. Drossart,et al.  The 2-μm polar haze of Jupiter , 1991 .

[10]  T. Johnson,et al.  Asteroids - Infrared photometry at 1.25, 1.65, and 2.2 microns , 1975 .

[11]  JOHN S. Lewis.  The clouds of Jupiter and the NH3—H2O and NH3—H2S systems , 1969 .

[12]  R. West,et al.  Jovian large-scale stratospheric circulation , 1991 .

[13]  Vasilii Ivanovich Moroz,et al.  STELLAR MAGNITUDE AND ALBEDO DATA OF VENUS , 2022, Venus.

[14]  S. Friedlander,et al.  Smoke, Dust and Haze: Fundamentals of Aerosol Behavior , 1977 .

[15]  U. Fink,et al.  The spectrum of the planetary nebula NGC 7027 from 0.9 to 2.7 microns , 1976 .

[16]  Steven W. Squyres,et al.  2 μm Spectrophotometry of Jovian Stratospheric Aerosols—Scattering Opacities, Vertical Distributions, and Wind Speeds , 1996 .

[17]  B. Dahneke.  Simple Kinetic Theory of Brownian Diffusion in Vapors and Aerosols , 1983 .

[18]  J. Hansen,et al.  Light scattering in planetary atmospheres , 1974 .

[19]  Thomas B. McCord,et al.  Jupiter and Saturn - Near-infrared spectral albedos , 1979 .

[20]  G. Neugebauer,et al.  Infrared standard stars , 1982 .

[21]  M. Tomasko,et al.  Clouds, aerosols, and photochemistry in the Jovian atmosphere , 1986 .

[22]  D. Strobel.  Photochemistry of the Reducing Atmospheres of Jupiter, Saturn and Titan , 1983 .

[23]  K. Baines,et al.  Absolute Reflectivity Spectra of Jupiter: 0.25–3.5 Micrometers , 1996 .

[24]  JOHN S. Lewis.  Observability of spectroscopically active compounds in the atmosphere of Jupiter , 1969 .

[25]  K. Strong,et al.  Spectral parameters of self- and hydrogen-broadened methane from 2000 to 9500 cm-1 for remote sounding of the atmosphere of jupiter , 1993 .

[26]  J. Martonchik,et al.  Optical properties of NH3 ice from the far infrared to the near ultraviolet. , 1984, Applied optics.

[27]  P. Gierasch,et al.  Zonal mean properties of Jupiter's upper troposphere from voyager infrared observations , 1986 .