地球物理流體力學課件：haurwitz-lecture13

1、Michael E. McIntyre, Dept of Applied Mathematics 3 revs/sec (!),Sommeria, Myers, and Swinney, Nature 1989 86.4 cm dia.; 3 revs/sec (!) PV map and dye map near-identical.,Sommeria, Myers, and Swinney, Nature 1989 86.4 cm dia.; 3 revs/sec (!) PV map and dye map near-identical. Strong jet, very tight e

2、ddy-transport barrier.,Sommeria, Myers, and Swinney, Nature 1989 86.4 cm dia.; 3 revs/sec (!) PV map and dye map near-identical. Strong jet, very tight eddy-transport barrier. Dye put in 500 revs. earlier.,PV in a 2-D idealized “stratosphere” (Juckes wave mechanism correlates vertical and horizontal

3、 velocity fluctuations):,z,u, 0,Here the “anti-frictional” effects are simple to understand (motion essentially incompressible; wave mechanism correlates vertical and horizontal velocity fluctuations):,z,u,The real QBO: fundamentally similar even though more complicated. Part of the case for this is

4、 the Michelson-Morley principle (Wallace wave mechanism correlates vertical and horizontal velocity fluctuations):,z,u,The real QBO: fundamentally similar even though more complicated. Part of the case for this is the Michelson-Morley principle (Wallace ,For more detail, websearch ”lucidity principl

5、es” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,History reminds us how science is a struggle with unconscious assumptions; and heres another reminder (that we all make them):,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”st

6、aircase”, ”Rosenbluth”.,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,homogeneous-turbulence assumption, as already discussed,Paradigm chang

7、es often involve exposing unconscious assumptions that are wrong. E.g.,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,small-is-unimportant assumption (counterexample: amplifier input signal),homogeneous-turbulence assumption,

8、as already discussed,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,energetics assumption (counterexamples: Stewartson-Warn-Warn critical layer, amplifier input and power-supply circuitry),For more detail, websearch ”lucidity principles” then back to my home pag

9、e at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier,homogeneous-turbulence assumption, as already discussed,Paradigm

10、 changes often involve exposing unconscious assumptions that are wrong. E.g.,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,energetics assumption (counterexamples: Stewartson-Warn-Warn critical layer, amplifier input and power

11、-supply circuitry),small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier, with complex multi-timescale circuitry ,homogeneous-turbulence assumption, as already discus

12、sed,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,energetics assumption (counterexamples: Stewartson-Warn-Warn critical layer, amplifier inp

13、ut and power-supply circuitry),small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier, with complex multi-timescale circuitry some parts more sensitive than others.,ho

14、mogeneous-turbulence assumption, as already discussed,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,energetics assumption (counterexamples:

15、Stewartson-Warn-Warn critical layer, amplifier input and power-supply circuitry),A = B assumption: “an equation A = B means that B causes A.”,small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climat

16、e system as a noisy amplifier, with complex multi-timescale circuitry some parts more sensitive than others.,homogeneous-turbulence assumption, as already discussed,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,energetics assumption (counterexamples: Stewartson

17、-Warn-Warn critical layer, amplifier input and power-supply circuitry),For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,A = B assumption: “an equation A = B means that B causes A.”,small-is-unimportant assumption (counterexample

18、: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier, with complex multi-timescale circuitry some parts more sensitive than others.,homogeneous-turbulence assumption, as already discussed,Paradigm changes often i

19、nvolve exposing unconscious assumptions that are wrong. E.g.,(As if it were a line of computer code.),energetics assumption (counterexamples: Stewartson-Warn-Warn critical layer, amplifier input and power-supply circuitry),For more detail, websearch ”lucidity principles” then back to my home page at

20、 ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,A = B assumption: “an equation A = B means that B causes A.”,small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier, with c

21、omplex multi-timescale circuitry some parts more sensitive than others.,You may laugh! But Ive often encountered exactly this assumption, and in more than one context.,homogeneous-turbulence assumption, as already discussed,Paradigm changes often involve exposing unconscious assumptions that are wro

22、ng. E.g.,(As if it were a line of computer code.),energetics assumption (counterexamples: Stewartson-Warn-Warn critical layer, amplifier input and power-supply circuitry),For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,A = B as

23、sumption: “an equation A = B means that B causes A.”,small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier, with complex multi-timescale circuitry some parts more sen

24、sitive than others.,You may laugh! But Ive often encountered exactly this assumption, and in more than one context.,homogeneous-turbulence assumption, as already discussed,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,(As if it were a line of computer code.),en

25、ergetics assumption (counterexamples: Stewartson-Warn-Warn critical layer, amplifier input and power-supply circuitry),For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,e.g., “pressure gradient causes geostrophic motion.”,A = B a

26、ssumption: “an equation A = B means that B causes A.”,small-is-unimportant assumption (counterexample: amplifier input signal) Remark: to make sense of the Pleistocene climate record, need to recognize the climate system as a noisy amplifier, with complex multi-timescale circuitry some parts more se

27、nsitive than others.,For meridional circulations, A = B is the equation for temperature or potential temperature in the mean-circulation model: B = mean heating rate, A = (TEM residual) mean vertical velocity times the static stability of the stable stratification.,You may laugh! But Ive often encou

28、ntered exactly this assumption, and in more than one context.,homogeneous-turbulence assumption, as already discussed,Paradigm changes often involve exposing unconscious assumptions that are wrong. E.g.,(As if it were a line of computer code.),energetics assumption (counterexamples: Stewartson-Warn-

29、Warn critical layer, amplifier input and power-supply circuitry),The old idea that the right-hand side B can be regarded as prescribed, and therefore the circulations as thermally driven is, indeed, just an A = B assumption.,The old idea that the right-hand side B can be regarded as prescribed, and

30、therefore the circulations as thermally driven is, indeed, just an A = B assumption. But hang on whats wrong with that? Whats wrong with a thought-experiment in which one prescribes the heating rate?,The old idea that the right-hand side B can be regarded as prescribed, and therefore the circulation

31、s as thermally driven is, indeed, just an A = B assumption. But hang on whats wrong with that? Whats wrong with a thought-experiment in which one prescribes the heating rate? Answer: some thought-experiments are better than others.,The old idea that the right-hand side B can be regarded as prescribe

32、d, and therefore the circulations as thermally driven is, indeed, just an A = B assumption. But hang on whats wrong with that? Whats wrong with a thought-experiment in which one prescribes the heating rate? Answer: some thought-experiments are better than others. Think about pushing a plate along a

33、dinner table. We can declare that the friction force B is prescribed but does that correspond to a good thought-experiment (?),The old idea that the right-hand side B can be regarded as prescribed, and therefore the circulations as thermally driven is, indeed, just an A = B assumption. But hang on w

34、hats wrong with that? Whats wrong with a thought-experiment in which one prescribes the heating rate? Answer: some thought-experiments are better than others. Think about pushing a plate along a dinner table. We can declare that the friction force B is prescribed but does that correspond to a good t

35、hought-experiment (?) The stratosphere and mesosphere and the interiors of solar-type stars are all thermally-relaxing systems.,The old idea that the right-hand side B can be regarded as prescribed, and therefore the circulations as thermally driven is, indeed, just an A = B assumption. But hang on

36、whats wrong with that? Whats wrong with a thought-experiment in which one prescribes the heating rate? Answer: some thought-experiments are better than others. Think about pushing a plate along a dinner table. We can declare that the friction force B is prescribed but does that correspond to a good

37、thought-experiment (?) The stratosphere and mesosphere and the interiors of solar-type stars are all thermally-relaxing systems. So as with the friction on the dinner plate its more insightful to regard the heating rate B as part of the response to some forcing.,The old idea that the right-hand side

38、 B can be regarded as prescribed, and therefore the circulations as thermally driven is, indeed, just an A = B assumption. But hang on whats wrong with that? Whats wrong with a thought-experiment in which one prescribes the heating rate? Answer: some thought-experiments are better than others. Think

39、 about pushing a plate along a dinner table. We can declare that the friction force B is prescribed but does that correspond to a good thought-experiment (?) The stratosphere and mesosphere and the interiors of solar-type stars are all thermally-relaxing systems. So as with the friction on the dinne

40、r plate its more insightful to regard the heating rate B as part of the response to some forcing. So “gyroscopic pumping” or “downward control” thought-experiments are better.,Summary: two paradigms with great explanatory power:, The radiation-stress-dominated atmosphere, Inhomogeneous PV mixing too

41、 good to be true?,For more detail, websearch ”lucidity principles” then back to my home page at ”Encyclopedia”, ”staircase”, ”Rosenbluth”.,Old paradoxes resolved by recognizing the spatial inhomogeneity and the wave or radiation-stress part of the jigsaw., cf. the old “turbulent stress-dominated”. A

42、nd, re Rossby-wave part,No! Its an observed reality explaining, e,g, the typical, ubiquitous strong-jet and eddy-transport-barrier structures. Understandable via the PV-inversion scale effect.,And watch out for unconscious thought-experiments!,(No time for the following slides:),The sunniest place o

43、n earth is the coldest place on earth.,Not a radiative-photochemical mystery! Just long-range momentum transport by gravity waves: an anti-frictional force field driving a mean meridional circulation through a mechanical “gyroscopic pumping” action. This was not understood when I was a postdoc in 1968. Meridional circulations of this ki