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The EUROCS stratocumulus case: Observations and numerical - - PowerPoint PPT Presentation

Oct 10, 2023 217 likes •405 views

The EUROCS stratocumulus case: Observations and numerical simulations of the diurnal cycle of stratocumulus Peter Duynkerke Stephan de Roode Herve Grenier* Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands

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The EUROCS stratocumulus case: Observations and numerical simulations of the diurnal cycle of stratocumulus

Peter Duynkerke Stephan de Roode Herve Grenier*

Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands * Meteo France Toulouse

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Contents

  • Description of the EUROCS stratocumulus case
  • Results from LES and Single Column models
  • Sensitivity studies
  • Summary & Conclusions
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The EUROCS stratocumulus case: The diurnal cycle of stratocumulus as observed during FIRE

(GOES satelllite)

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Motivation

Source: Duynkerke and Teixeira 2001

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The EUROCS stratocumulus case

Observations

  • radiosonde (mean vertical profiles)
  • sodar (inversion height)
  • ceilometer (cloud base)
  • aircraft (turbulence)
  • microwave radiometer (liquid water path)

Numerical simulations

  • Large-Eddy Simulation & Single Column Mode
  • same radiation schemes
  • prescribed large-scale forcing
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Contractors + associated LES SCM CNRM-GAME y ECMWF y KNMI y UL INM y y SMHI IMAU y LMD y MPI y y UKMO y y GCSS-WG1 2 1 TOTAL 6 8

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Analysis strategy

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LES results - Mean surface energy balance from 12 to 36 LT

Laboratories H [W m-2] LE [W m-2] Fs(z=0) [W m-2] LWP [g m-2] IMAU 3.1 23.1 211 90 MPI 4.1 23.0 171 116 UKMO 7.4 20.3 134 166 INM 5.1 22.6 178 128 NCAR 13.9 24.3 201 109 WV 8.6 28.1 185 95 mean LES 7.0 ± 3.9 23.6 ± 2.6 180 ± 27 117 ± 28

Mean observed Fs: 190 Wm-2

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LES results - Liquid water path

night time day time

100 200 300 12 24 36 48

MMobs

  • bs

Za Ch Lo Sa Mo Le

LWP [ g m

  • 2 ] or [

m ]

Local time [h]

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LES results - Turbulence

0.05 0.1 0.15 0.2 0.25 0.3 0.35 100 200 300 400 500 600 700 800

  • bs.

Za Ch Lo Sa Mo Le

w

2 [ m 2 s

  • 2 ]

z [ m ]

vertical velocity variance during the night

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LES results - Sensitivity to inversion jumps

  • 10
  • 8
  • 6
  • 4
  • 2

2 5 10 15 20

CTEI

  • v = 0

FIRE I radiosondes initial

q t [g/kg]

  • l [K]
  • 10
  • 8
  • 6
  • 4
  • 2

2 5 10 15 20

CTEI

  • v = 0

FIRE I radiosondes initial

q t [g/kg]

  • l [K]
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LES results - Sensitivity to inversion jumps - LWP

100 200 300 6 12 18 24

l = 12K , qt= -3 g kg

  • 1

l = 9K qt= -1 g kg

  • 1

qt= -5 g kg

  • 1

LWP [ g m

  • 2 ] or [

m ]

Local time [h]

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SCM results - Mean surface energy balance from 12 to 36 LT

Laboratories H [W m-2] LE [W m-2] Fs(z=0) [W m-2] LWP [g m-2] KNMI 4.0 26.2 272 33 INM 6.1 21.0 140 157 CSU 14.6 24.5 250 160 LMD 0.2 15.9 237 41 MPI 29.6 5.5 119 156 CNRM 23.9 24.2 281 56 UKMO 10.2 26.0 173 75 CNRM 2

  • 29.7

271 16 ECMWF 0.1 39.0 280 79 mean SCM 9.9 ± 10.9 23.6 ± 9.2 225 ± 64 87 ± 59 mean LES 7.0 ± 3.9 23.6 ± 2.6 180 ± 27 117 ± 28

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SCM results - LWP

50 100 150 200 250 12 24 36 48

MMobs

  • bs

Za LES Len Sa La Che Ch Gr Lo Pi Koe

LWP [ g m

  • 2 ] or [

m ] local time [hours]

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Data availability http://www.phys.uu.nl/~wwwimau/research/atm_dyn/EUROCS_PART_I/eurocs.html/

LES: SCM: A Chlond 3D LES 2.5 km A Chlond Quasi 3D LES 2.5km D Lewellen 3D LES Standard D Lewellen 3D Shear at inversion A Lock standard A Lock D=7.5E-6 17m, horiz resolution A Lock shear at inversion A Lock 17m horiz resoln M van Zanten (IMAU) 3D LES 2.5km domain CH Moeng 3D LES 2.5km domain E Sanchez/J Cuxart 3D-LES FIRE case Sensitivity results with IMAU LES A Chlond SCM: Version May03 A Cheinet (LMD) SCM Herve Grenier Version May04 CNRM- standart Martin Koehler (standard) C Lappen SCM G Lenderink SCM A Lock GCM standard resolution A Lock GCM resolution D=7.5E-6 JM Piriou SCM 60 levels timestep 300.000 E Sanchez/J Cuxart SCM

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Papers

  • P. G. Duynkerke, S. R. de Roode + case participants: The EUROCS stratocumulus

case: Observations and numerical simulations of the diurnal cycle of stratocumulus.

  • M. Kohler, M. C. van Zanten and S. R. de Roode: The impact of the diurnal cycle
  • f the subsidence on the EUROCS stratocumulus case.
  • A. Chlond, F. Müller and I. Sednev: Numerical simulation of the diurnal cycle of

marine stratocumulus during FIRE - A LES, SCM and GCM modelling study Related work

  • S. R. de Roode, P. G. Duynkerke and H. J. J. Jonker, 2002: Large Eddy

Simulation: How large is large enough? Submitted to the J. Atmos. Sci.

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Conclusions: What did we learn?

  • EUROCS stratocumulus case

Contains all the relevant physical processes (turbulence, radiation)

  • > first intercomparison of the diurnal cycle including shortwave radiation

LES models simulate the diurnal cycle fairly well

  • Surface energy balance

Solar downwelling radiation major component (LWP) Computed liquid water paths lead to largest uncertainties (entrainment)

  • Single column models

Large individual variation in the results Complete data set available (observations & LES results)

  • > facilitates the assessment of strength and weaknesses of individual SCMs