The infrared interferometer spectrometer on Voyager 2 obtained thermal emission spectra of Neptune with a spectral resolution of 4.3 cm(-1). Measurements of reflected solar radiation were also obtained with a broadband radiometer sensitive in the visible and near infrared. Analysis of the strong C(2)H(2) emission feature at 729 cm(-1) suggests an acetylene mole fraction in the range between 9 x 10(-8) and 9 x 10(-7). Vertical temperature profiles were derived between 30 and 1000 millibars at 70 degrees and 42 degrees S and 30 degrees N. Temperature maps of the planet between 80 degrees S and 30 degrees N were obtained for two atmospheric layers, one in the lower stratosphere between 30 and 120 millibars and the other in the troposphere between 300 and 1000 millibars. Zonal mean temperatures obtained from these maps and from latitude scans indicate a relatively warm pole and equator with cooler mid-latitudes. This is qualitatively similar to the behavior found on Uranus even though the obliquities and internal heat fluxes of the two planets are markedly different. Comparison of winds derived from images with the vertical wind shear calculated from the temperature field indicates a general decay of wind speed with height, a phenomenon also observed on the other three giant planets. Strong, wavelike longitudinal thermal structure is found, some of which appears to be associated with the Great Dark Spot. An intense, localizd cold region is seen in the lower stratosphere, which does not appear to be correlated with any visible feature. A preliminary estimate of the effective temperature of the planet yields a value of 59.3 +/- 1.0 kelvins. Measurements of Triton provide an estimate of the daytime surface temperature of 38(+3)(-4) kelvins.

Voyager radio occultation and infrared spectrometer measurements are used to obtain an estimate of the helium abundance in the atmosphere of Neptune. It is found that the shape of the measured spectrum cannot be well matched by spectra calculated from atmospheric models that include only gaseous opacity. The most plausible explanation of the observed spectral shape appears to require the existence of an additional opacity source associated with clouds or hazes. The data can be fit with either a tropospheric or a stratospheric cloud model. If a tropospheric cloud is invoked, an optical thickness at 200 cm−1 between 1 and 8 is required, depending on the particle size assumed. For a stratospheric cloud an optical thickness between 0.2 and 0.8 is required. Optical constants for methane ice are used, but ethane has similar optical properties in this spectral region. Assuming no modification to the temperature profile is required other than a molecular weight adjustment, a combination of gas and cloud opacities produces a good fit to the spectrum for a helium mole fraction qHe = 0.190 ± 0.032, corresponding to a mass fraction Y = 0.32 ± 0.05. Within the measurement uncertainties the Neptune helium abundance may be compatible with that of Uranus and, marginally, with the protosolar value. However, models in which the outer part of the primitive solar nebular was enriched in CO and N2, leading to an enhanced atmospheric He/H2 ratio, cannot be ruled out at this time.

The mixing ratio profile of N2O5 has been inferred from high‐resolution emission spectra obtained with a balloon‐borne Fourier spectrometer (SIRIS). The observations were taken for the period from midnight to predawn on September 16, 1986 at 32° N latitude. The inferred volume mixing ratio from nighttime average spectra has a peak of ∼ 1.8 × 10−9 in the 32‐35 altitude range. The inferred mixing ratio is generally less than the theoretical predictions from a 1‐D model.

To the authors' knowledge, the LTN has not been previously examined as a donor nerve for facial nerve reanimation procedures. Based on the results of this cadaveric study, the use of the LTN may be considered for such surgical maneuvers.

No abstract