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Zonally averaged thermal balance and stability models for nitrogen polar caps on Triton
Author(s) -
Stansberry John A.,
Lunine J. I.,
Porco C. C.,
McEwen A. S.
Publication year - 1990
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl017i010p01773
Subject(s) - emissivity , equator , latitude , atmospheric sciences , albedo (alchemy) , polar , longitude , northern hemisphere , southern hemisphere , environmental science , physics , geology , astrophysics , astronomy , optics , art , performance art , art history
We have analyzed Voyager four color imaging data of Triton to calculate the bolometric hemispheric as a function of latitude and longitude. Zonal averages of these data have been incorporated into a thermal balance model involving insolation, reradiatation and latent heat of sublimation of N 2 ice for the surface. The current average bolometric albedo of Triton's polar is 0.8, implying an effective temperature of 34.2K and a surface pressure of N 2 of 1.6 μb for unit emissivity. This pressure is an order of magnitude lower than the surface pressure of 18 μb inferred from Voyager data [Broadfoot et al., 1989; Conrath et al., 1989], a discrepancy that can be reconciled if the emissivity of the N 2 on Triton's surface is 0.66. The model predicts that Triton's surface north of 15° N latitude is experiencing deposition of N 2 frosts, as are the bright portions of the south polar cap near the equator. This result explains why the south cap covers the entire southern hemisphere of Triton. Initial results from a seasonal model are also described briefly, although they do not agree with the Voyager observations.