From
his web site:Prof. Katz is working on problems in boundary layer hydrodynamics. He analyzed the process of rapid adiabatic blowdown of a pressure vessel, and derived a novel dimensionless number describing the importance of buoyancy-driven circulation, resulting from the competition between conductive heating of the gas near the wall and the adiabatic cooling of the gas in the interior of the vessel. He is now working on double-diffusive boundary layers, such as those between water and glycerin or plasmas of different composition in laser-fusion targets, in which both momentum and mass diffuse, and in which the composition (affected by mass diffusion) affects the viscosity (that determines the diffusion of momentum).
I'm less troubled by his abhorrent social views than the possibility that he's got a technical bias toward simplifying more than is allowed by the physics. For instance, he is pushing an atmospheric model "for pedagogical purposes" that seems designed to bolster climate-change skepticism:
Prof. Katz has studied the problem of geoengineering to counteract the warming effects of anthropogenic carbon dioxide by introducing artificial scattering aerosols into the stratsophere. This is an old idea, inspired by the observation of cooling following large volcanic eruptions that loft sulphur oxides to the stratosphere where they form sulfuric acid droplets, a connection first noted by Benjamin Franklin. He has investigated the questions of determining the best material to use, the best form in which to loft it, and the best means of lofting. The tentative answers are sulfur, liquid hydrogen sulfide and rockets. In any such scheme questions of chemical kinetics arise that are not important in natural volcanic injection.
In a related project, Prof. Katz has developed a simple pedagogical one-equation greenhouse warming model controlled by the infrared opacity of water vapor, the most important greenhouse gas. In this model the climate is generally intrinsically unstable, with two stable limit points, glaciation and warm interglacials. Then our present intermediate state can only be maintained by continual geoengineering, with or without anthropogenic greenhouse gases.
My inclination would be to assume that Steve Chu had good reasons for appointing him in the first place, and I'd trust Chu's judgment as a physicist. But it also seems like there probably are people with at least comparable qualifications who wouldn't bring along so much negative political baggage. I'm glad he's out, but more because I think he comes to his science with an axe to grind (why else pretend that water vapor "controls" greenhouse warming?).