cloud cover parameterisationMartin Köhler, DWD

ICON cloud communityMaike Ahlgrimm, Uli Blahak, Daniel Klocke, Alberto de Lozar, Ekaterina Machulskaya,

Matthias Raschendorfer, Sophia Schäfer, Axel Seifert

wallpaperaccess.com

ICON-atmo solar bias ICON-coupled SST bias

SST bias vs ERA5 TOA net solar bias vs CERES

ICON NWP 40km12 months 2019

Sophia Schäfer, Martin Köhler

ICON-seamless 160km12th month 1979(1st prototype)

Stephan Lorenz, Martin Köhler, Rene Redler

Clouds in ICON

• dynamics: 1/0• microphysics: 1/0• convection: small cloud updraft• turbulence: Gaussian distribution for buoyancy flux• radiation: diagnostic cloud cover

wallpaperaccess.com

diagnostic ICON cloud cover

k

k+1/2

k-1/2

Du ql,up

liquidvapor

qsat

PDF

qq

∆q ∆q

qtopqbot

p

¶CC¶t

= (1-CC)Du

r-CCt decay

Tuning Parameters

tune_box_liq box width liquid cloudtune_box_liq_asy asymmetry liquid cloudtune_thicklayfac in-box overlapicpl_turb_clc turb. coupling to cloudlcalib_clcov post-calibration of TCC,…

… and more …

turbulent cloud convective cloud

EUREC4a 1.3.2020 NASA Worldview

TERRA VIIRSAQUA

equator overpass:10:30am

equator overpass:1:00pm

equator overpass:1:30pm

EUREC4a 7.2.2020 NASA Worldview

TERRA VIIRSAQUA

equator overpass:10:30am

equator overpass:1:00pm

equator overpass:1:30pm

EUREC4a 7.2.2020 NASA Worldview

TERRA VIIRSICON

equator overpass:10:30am

equator overpass:1:00pm12:00am (36h forecast)

ICON at 1.25km1º ⎼ 23º North-66º ⎼ -44ºEast

EUREC4a 1.25km ICONsimulations: Daniel Klocke

specific humidity

wTKE

liquid water cloud cover θv

simulation• 1.25km resolution• 36h forecast• 7.2.2020 12UTC• mean over ocean only• no convective parameterisation• TKE parameterisation• fractional cloud cover• graupel 1-moment microphysics

total water (qv+qc) PDF

3000m

4000m

2000m

1500m

1000m

Adrian Tompkins, 2002

beta distribution G:

beta function B:

PDF (cloud cover, total water) height

Box Width 20km

4000m

1500m

3000m 2000m

1000m

PDF (cloud cover, total water) resolution

Box Width 10km Box Width 20km Box Width 40km Box Width 80km

dw/dz

Box Width 20km

4000m

1500m

3000m 2000m

1000m

TKE

Box Width 20km

4000m

1500m

3000m 2000m

1000m

diagnostic ICON cloud cover

k

k+1/2

k-1/2

Du ql,upliquidvapor

qsat

PDF

qq qtopqbot

p

Beta distributionTompkins JAS (2002)

mean: dynamicsstandard deviation: TKE scheme

skewness: convection

goals:• combined cloud with turbulent and

convective source terms• diagnostic, simplified• resolution dependant• with and without convection

parameterisation

Extra Slides

EUREC4a 1.3.2020 NASA Worldview

TERRA VIIRSICON 1.25km

equator overpass:10:30am

equator overpass:1:00pm

snapshot:12:00am (36h forecast)

PDF (cloud cover, total water) height

Box Width 40km

theta,v

Box Width 20km

4000m

1500m

3000m 2000m

1000m

w

Box Width 20km

4000m

1500m

3000m 2000m

1000m

W,local – W,mean20km