Comparison of HIRLAM data with Sodankyl

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Comparison of HIRLAM data with Sodankylä
soundings tools and results

• Evgeny Atlaskin
• Russina State Hydrometeorological University
• Saint-Petersburg

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HIRLAM data

• Vertical scale is determined by parameters A and
  B that are given for additional model levels
• Pk1/2 Ak1/2 Bk1/2Ps
• and for main model levels
• Pk Ak BkPs

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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

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Comparison of temperature and dew point
temperature

• Sounding data are calculated at the HIRLAM model
  levels determined by the same expression as for
  HIRLAM
• Pk1/2 Ak1/2 Bk1/2Ps_obs
• Ps_obs is an observational surface pressure
• Linear interpolation of (dew point) temperature
  with respect to logarithmic pressure is applied
  for those levels

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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

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• - case of absence of souding points within the
• model layer

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Ground based comparisons

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

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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