Comparison of HIRLAM data with Sodankylä soundings – tools and results

Evgeny AtlaskinRussina State Hydrometeorological UniversitySaint-Petersburg

HIRLAM data

Vertical scale is determined by parameters A and B that are given for additional model levels

Pk±1/2 = Ak±1/2 + Bk±1/2Ps

and for main model levels

Pk = Ak + BkPs

Sounding data

12 hour measurements at different heights: -temperature -relative humidity -wind speed -some synoptic masurements

Vertical scale is not fixed, i.e. there are no constant levels

Comparison of temperature and dew point temperature

Sounding data are calculated at the HIRLAM model levels determined by the same expression as for HIRLAM

Pk±1/2 = Ak±1/2 + Bk±1/2Ps_obs

Ps_obs is an observational surface pressure

Linear interpolation of (dew point) temperature with respect to logarithmic pressure is applied for those levels

uplow

uplowklowlowk PP

TTPPTT

lnln)ln(ln 2/12/1

Determination of sounding temperatures at main model levels

Method of trapezes is applied

- case when one or more sounding points are inside a model layer

N

iii

ii

kkk PP

TT

PPT

11

1

2/12/1

)ln(ln2lnln

1

- case of absence of souding points within the model layer

22/12/1

kkk

TTT

Ground based comparisons

Mast data available for comparison: Temperature Radiation fluxes Sensible heat flux Latent heatflux Momentum flux

Conclusions

Tools for comparisons of HIRLAM data with soundings are prepared and are available to use in boundary layer

Temperature time series at Sodankylä mast (surface 3m, 32m) could be plotted for comparison with HIRLAM T2m

Flux measurements are also prepared in appropriate format for further usage