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Atm S 547 Lecture 7, Slide 1 Baroclinic Ekman spirals

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Page 1: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 1

Baroclinic Ekman spirals

Page 2: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 2

Surface wind crossing angle vs. thermal wind

Hoxit 1974

Page 3: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 3

Cold advection: cross-isobar flow

Warm advection: Along-isobar flow

Over water: along-isobar flow

Page 4: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 4

Horizontal sections of u’ from LES of shear-driven turbulence

Page 5: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 5

LES vertical section of u’ in shear-driven PBL

Page 6: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 6

Rolls in LES weakly convective PBL

Page 7: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 7

Convective PBL (Rayleigh-Benard)

Page 8: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 8

Velocity variance profiles

Page 9: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 9

TKE budgets Moeng and Sullivan 1994

Page 10: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 7, Slide 10

LES-simulated entrainment event in a convective PBL

Sullivan et al. 1998

Page 11: Baroclinic Ekman spiralsbreth/classes/AS547/lect/lect7-slides.pdf · LES vertical section of u’ in shear-driven PBL . Atm S 547 Lecture 7, Slide 6 Rolls in LES weakly convective

Atm S 547 Lecture 8, Slide 11

Observational support for DCBL entrainment closure

′w ′b (h) = −0.2B0