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Satellite Data in the Verificationof Model cloud forecasts

Christoph Zingerle

Tartu, 24. – 26. Jan. 2005

HiRLAM mini workshop on clouds and convection

a convective case in summer 2003seen from NOAA satellites

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Outline

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

- Verification: Alignments for Satellite Data

- Satellite Data

- Case studies

- Outlook / Future

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Verification

Comparing Observations to Forecast

- Point measurements – volumes / fields

- Observation and forecast are on different scale / location

- Problems verifying fields of meteorological data e.g. rain, clouds, radar reflectivity

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

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Verification

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

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Verification

temperaturehumiditycloud fractioncloud liquid watercloud ice watertotal cloud water surface data (p, T, rH)

RTTOV-8

- Simulates clear/cloudy multilevel infrared and

microwave radiances

- Consistent random-overlap scheme for

clouds in different levels

- Multiphase cloud field: water / ice / mixed

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

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Satellite Data

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

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NOAA AVHRR satellite image

- Re-sampling needed

- Preprocessed AVHRR image (calibrated and navigated) pixel center in the grid-box corresponding to the HIRLAM grid pixel assigned to this grid-box

- Assumptions:

HIRLAM grid value represents average over all the values in box

Neighbouring pixels tend to have similar properties

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Satellite Data

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full resolution, 30.4.2004 (10.8µ) after re-sampling, 30.4.2004 (10.8µ)

HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Case

15. – 17. July 2005

- All NOAA satellite observations of that periode

- Small domain covering little more than Scandinavia

- Forecasts re-run at ECMWF in May 2004 with reference HiRLAM of last summer.

- Irregular distribution (time and space) of the satellite overpasses

MODEL:

SATELLITE DATA:

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Case

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Caseall observations

surface / clear sky

convection observed

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Case

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Casemorning

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Case

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Caseafternoon

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Caseafternoon

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Casenight

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Convective Caseafernoon 2 (+34h)

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Evolution histogram

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Evolution histogram

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Conclusions

- Higher surface temperatures observed than forecasted

- Convective clouds in model general to warm – convection not strong enough?

- Advected clouds have smaller differences

Satellite Data:

- RTM’s are a very useful tool also in verification

- Up / Dowonscaling methods have to be tested more extensively (true observation?)

- Continuous observations are needed

- Error decompostion needed! (postion, area, intensity)

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HiRLAM mini workshop, Tartu 24. – 26. Jan. 2005

Future

- Continuous observations – METEOSAT 7/8

- This case: more forecasts – more details (lead time)

- Adaption of error decompostion software

- Satellite / SYNOP comparison