Statistics – Computation
Scientific paper
Sep 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009dps....41.2403s&link_type=abstract
American Astronomical Society, DPS meeting #41, #24.03
Statistics
Computation
Scientific paper
Several groups have performed 3D studies of convection in spherical shells to test the hypothesis that the strong jet streams on Jupiter, Saturn, Uranus, and Neptune result from convection throughout the molecular envelopes. Due to computational limitations, these simulations must be performed at parameter settings far from Jovian values. However, because such investigations are generally non-dimensionalized, it has remained unclear how the simulated heat fluxes (which drive the convection) compare to planetary values and therefore the extent to which the simulated jet structure relates to that within the actual planets. We show that published simulations generally adopt heat fluxes 5-10 orders of magnitude larger than the planetary values; such overforcing is used partly because the large planetary mass would lead to computationally prohibitive spin-up times at realistic planetary heat fluxes and partly because the large numerical viscosities must be overcome with strong forcing to yield realistic jet speeds. To connect published simulations to the real planets, we construct a scaling based on mixing-length theory suggesting a relation between the wind speed, heat flux, and numerical viscosities; this scaling favorably matches numerical simulations using an anelastic non-hydrostatic general circulation convection model. Christensen suggested that there exists a regime in these models where the wind speed is independent of the numerical viscosities. We show based on mixing length estimates that if such a regime exists, jet speeds in the envelopes should scale as heat flux to the 1/4 power. This compares favorably with an empirical fit to simulations by Christensen, which suggest a dependence on the heat flux to the 1/5 power. When extrapolated to the real heat fluxes, both scalings suggest that the mass-weighted jet speeds in the molecular envelopes of the giant planets are much weaker (by an order of magnitude or more) than the speeds measured at cloud level.
Flierl Glenn R.
Kaspi Yohai
Showman Adam P.
No associations
LandOfFree
Scaling Laws for Convection and Jet Speeds on Giant Planets does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Scaling Laws for Convection and Jet Speeds on Giant Planets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scaling Laws for Convection and Jet Speeds on Giant Planets will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1332555