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

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

Nov 22, 2022 462 likes •703 views

The EUROCS stratocumulus case: Observations and numerical simulations of the diurnal cycle of stratocumulus Status on the intercomparison; data availability, deliverables, papers Peter Duynkerke Stephan de Roode Herve Grenier (1) Institute for

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The EUROCS stratocumulus case: Observations and numerical simulations of the diurnal cycle of stratocumulus Status on the intercomparison; data availability, deliverables, papers

Peter Duynkerke Stephan de Roode Herve Grenier(1)

Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands

(1)CNRM, Toulouse, France

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Contents

  • LES sensitivity studies

Cloud-top jumps and entrainment Large-scale advection

  • New SCM simulations
  • Papers
  • Summary & Conclusions
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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 ] 200 400 600 800 6 12 18 24 height [m] local time [hours] cloud depth 200 400 600 800 6 12 18 24 height [m] local time [hours] cloud depth 200 400 600 800 6 12 18 24 height [m] local time [hours] cloud depth

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Large-scale subsidence

  • No observations -> we rely on large scale models
  • Utrecht meeting:

IMAU: model not sensitive to applied subsidence rate MPI : opposite finding ECMWF subsidence (Martin Koehler)

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Large-scale forcing: EUROCS & ECMWF

Source: Martin Koehler (ECMWF)

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Large-scale forcing: EUROCS & ECMWF subsidence

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Tendencies due to large-scale advection in EUROCS case Subsidence and horizontal advection balance: d/dt(,q)FA = 0

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Large-scale forcing: LES sensitivity tests 1, Vary subsidence rate, but keep total large-scale forcing the same (d/dtFA=0) (Margreet van Zanten, IMAU)

  • 2. Vary large-scale horizontal advection, same subsidence rate

(Andreas Chlond, MPI)

  • 3. Vary large-scale horizontal advection in the boundary layer only

(Andreas Chlond, MPI)

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LES results - Sensitivity to subsidence

50 100 150 200 6 12 18 24

Za

  • div. x 2
  • div. x 0.5
  • div. x 0.1

LWP [ g m-2 ] or [ m ] local time [hours]

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LES results - Sensitivity to large-scale forcing (MPI)

dl dt

  • LS

7.5108 max z,500

  • Ks1
  • dqt

dt

  • LS

3.01011max z,500

  • kgkg1
  • s1
  • Experiment
  • Change large-scale forcing over the whole domain by ±25%
  • Same subsidence forcing
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LES results - Sensitivity to large-scale horizontal advection

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LES results - Sensitivity to large-scale horizontal advection in the BL only

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Large-scale tendencies: conclusion Different results are due to different tendencies in inversion jumps

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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 - Sensitivity to resolution and schemes

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SCM results - Sensitivity to resolution and schemes

  • Operational version

Additional sets: no precipitation, same radiation schemes:

  • STD1A: No convection scheme
  • STD1B: With convection scheme

STD1A_HR & STD1B_HR: high-resolution

  • > reduce numerical errors
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SCM results: data sets

OPERATIONAL STD1A STD1B STD1A_HR STD1B_HR MPI Y Y Y Y Y UKMO Y

  • INM

Y Y Y

  • METFR

Y Y Y Y Y KNMI Y Y Y Y Y ECMWF Y Y Y

  • Hard to generalize findings
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SCM results - Mean liquid water path [gm-2] from 12 to 36 LT

OPERATIONAL STD1A STD1B STD1A_HR STD1B_HR MPI 71.5 276.1 266.9 111.1 107.8 UKMO

  • INM

128.6 413.9 410.2

  • METFR(*)

0.1 30.7 31.9 38.7 43.9 KNMI 1.6 216.4 1.6 80.9 0.6 ECMWF 80.2 63.7 98.6

  • Resolution: MPI, KNMI
  • Convection scheme: KNMI
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SLIDE 20
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Physical processes in stratocumulus

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Conclusions

LES results and observations (to be included in summary paper)

  • Surface energy balance
  • Turbulence structure during night-time and day-time
  • Sensitivity studies

Inversion jumps, SST, windshear, subsidence Other papers

  • Subsidence diurnal cycle (Koehler et al., not sure to meet deadline)
  • Chlond et al.

SCM results

  • separate papers (model improvement, case study etc.)?????