FE 14

Preliminary validation results

of the

prognostic 3d-TKE-scheme

Gerd Vogel, Ursula SchubertDWD Potsdam

Zurich, September 2005

Outlook

Operational LM-prediction May 30, 2004

Lindenberg

OutlookOp. scheme (3tls)

Mellor&Yamada (3tls) Mellor&Yamada (2tls)

3d pTKE-scheme

Mellor&Yamada (2tls, ALM)

May 30, 2004

Meteorol.and Atm. Physics, 2005, 88, 23-38

Gassmann, A.:

Operational radiosonde ascents (temperature, humidity, wind components, every 6 hours, up to 25 km)

LIDAR-measurements (water vapour, all 10 min between 500m - 2000m, provided by MPI Hamburg only during field experiments)

Microwave profiler data (temperature , all 10 min, up to 25 km)

Windprofiler-, RASS-, SODAR-systems (wind components , virtual temperature, all 10 min, 200m-3000m)

Data of vertical sounding systems available from MO Lindenberg (DWD)

Outlook

Average over 8 days (weak winds only) in May and June 2004 (Lindenberg)

Outlook

Average over 8 days (weak winds only) during May and June 2004 (Lindenberg)

Prognostic 3d-TKE schemeMicrowave data

Comparisons with operational cross-sections based on LME-predictions daily available:http://www.dwd.de/de/FundE/Observator/MOL/mol1/passiv/mol1_pasf_e.htm

specified flux components:

i

j

j

iijmij x

u

x

uK

j

jhpdj xKcY

1

j

kjhj x

qKY

2

221211: mmmHm KKKK 332313: mmm

Vm KKKK

21: hhHh KKK 3: h

Vh KK

simplified anisotropicdiffusion approach

(momentum)

(heat)

aspect ratio[Dunst (1980)]

Vhm

Vhm

Vhm

222Hhm KK

z

2rK

z

aaarK ,,,.

)()cos()cos(:

1/21/2 )()( elKelK hVhm

Vm

Prandtl-Kolmogorov-specification

of vertical diffusion

Basic features of the prognostic 3d-TKE scheme

Outlook

Vertical velocity (12 UTC) 400 m

LMK 1d pTKE LMK 3d pTKE

Outlook

Vertical velocity

(12 UTC)

LMK 1d pTKE LMK 3d pTKE

Zonal height-cross section (j=175) Vertical velocity 12 UTC

LMK 1d pTKE LMK 3d pTKE

ConclusionsA proper accuracy check of the turbulence parameterisations used in the LM will only be possible if the model forcing from the surface has been improved. It’s intended to replace soil moisture, precipitation and radiation balance values at surface by measure- ments (or simulated data basing on them like soil moisture) in the whole LMK area.

Versatile vertical soundings available from Lindenberg (DWD) enable us to study thoroughly the changing boundary layer structures during the day. Based on them the model behaviour can be evaluated more comprehensively due to continuous compa- risons between measured and simulated meteorological quantities along the vertical.

The implementation of the horizontal heat and momentum fluxes improves the phy-sical content of the scheme. In order to find out how accurately the present prognostic 3d-TKE scheme describes the reality (e.g. simulation of convection rolls), further validation studies are necessary, also including satellite data which often reveal such convection rolls in nature, too.