Achterberg_et_al-2018-Geophysical_Research_Letters.pdf (1.65 MB)
Thermal Emission From Saturn's Polar Cyclones
journal contributionposted on 2019-07-05, 12:45 authored by RK Achterberg, FM Flasar, GL Bjoraker, BE Hesman, NJP Gorius, AA Mamoutkine, LN Fletcher, ME Segura, SG Edgington, SM Brooks
We have used data from the Cassini Composite Infrared Spectrometer to map the temperatures in Saturn's polar cyclones at the highest spatial resolution obtained during the Cassini mission. We find temperature contrasts of 7 K in the upper troposphere within 1.4° of both poles, roughly 50 percent larger than earlier measurements at lower spatial resolution. The polar hot spots weaken with depth, disappearing near 500 mbar. In the stratosphere, the polar hot spot becomes broader, extending 4° from the poles, and weakens with altitude disappearing near 1 mbar. A thermal relaxation model shows that the tropospheric hot spot is consistent with adiabatic heating from subsidence with a vertical velocity of about −0.05 mm/s above 500 mbar. The observed temperature gradients imply that the winds in the polar cyclone decay with increasing altitude over roughly three pressure scale heights above the 200‐mbar level.
NASA Cassini project Royal Society Research Fellowship European Research Council Consolidator. Grant Number: 723890
CitationAchterberg, R. K., Flasar, F. M., Bjoraker, G. L., Hesman, B. E., Gorius, N. J. P., Mamoutkine, A. A., et al. ( 2018). Thermal emission from Saturn's polar cyclones. Geophysical Research Letters, 45, 5312– 5319. https://doi.org/10.1029/2018GL078157
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
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