## Abstract

The Voyager 2 Ultraviolet Spectrometer measured the emission intensity of the He resonance line at 584 Å to be 0.34‐0.15+0.2 R on the day side of Neptune. Our calculations of the He 584 Å intensity at Neptune using partial frequency redistribution and inhomogeneous atmospheric models show that the product of the volume mixing ratio (mole fraction), f_{He}, and the eddy diffusion coefficient at the homopause, K_{h}, is f_{He}K_{h} = 10^{7} cm^{2} s^{−1} with upper and lower bounds to the uncertainty of about a factor of 3 and 9, respectively. If f_{He} is taken as the current Infrared Interferometer Spectrometer working value, f_{He} = 0.19, then K_{h} = 5×10^{7} cm^{2} s^{−1} with a similar uncertainty. This range of K overlaps that obtained from analysis of the hydrocarbon distributions on Neptune (Broadfoot et al., 1989).

Original language | English (US) |
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Pages (from-to) | 1709-1712 |

Number of pages | 4 |

Journal | Geophysical Research Letters |

Volume | 17 |

Issue number | 10 |

DOIs | |

State | Published - Sep 1990 |

## ASJC Scopus subject areas

- Geophysics
- Earth and Planetary Sciences(all)