http://mmmmail.com/julesandjames.xml http://mmmmail.com/julesandjames.xml en Wed, 19 Jun 13 18:04:14 +0000 Wed, 19 Jun 13 18:04:14 +0000 2 mmmmail.com http://mmmmail.com/tracker_image/julesandjames http://mmmmail.com/julesandjames.xml 144 42 en julesandjames@mmmmail.com Copyright 2013 http://mmmmail.com/julesandjames_5768677.html http://mmmmail.com/julesandjames_5768677.html From: David Young Reply-to: David Young David Young has left a new comment on your post "More on that recent sensitivity paper":
I'm going to perform a test here to see if Carl is anything more than an Al Gore bot. In any discrete realization of the Navier-Stokes equations or the hydrostatic approximation (which seems to rule out accurate simulation of cumulus convection) there is a numerical viscosity associated with the grid size. Now my research indicates that the Reynolds number for the atmosphere is quite large at the planetary scales and not small at smaller scales. If the grid doesn't resolve these viscous scales the real viscosity at the planetary scales, there is a very large nonphysical dissipation that will damp the dynamics. This is probably what Browning refers to in his papers as "unphysical dissipation". There is apparently even a "hyperviscosity" that is larger than the discrete viscosity. So, given this large artificial dissipation, why would you expect dynamics at any scale to be resolved?
In terms of the "scale" of the dynamics, this is just a fiction Carl and Bloom have come up with. The dynamics is the same at large scales as at small scales, it involves vortex evolution and dissipation. If Carl has ever gotten in one of those "crashing" airplanes, he can see this vortex dynamics at take off if the humidity is very near the saturation point. There are shear layers and boundary layer too in climate. In climate, they must be unresolved, but that's another issue. They must be included if at all through subgrid models. The "scale" issue seems to me to be an unscientific gloss that can only be rooted in a schoolyard bullying tactic: "My problem is harder than your problem." Perhaps acceptable in the Al Gore world of political smears and untruths, but not a very scientific statement, unless of course there might be some actual substance behind the bluster.
Posted by David Young to James' Empty Blog at 19/6/13 12:13 pm ]]> Wed, 19 Jun 2013 15:44:15 +0000