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Towards the operational cloud classification in Finland

Towards the operational cloud classification in Finland. Otto Hyvärinen COST 722 Expert Meeting, Helsinki, 9 June 2004. Contents. Cloud classification work with NOAA/AVHRR in FMI in Nowcasting SAF (PPS) Problems Future plans. FMI approach to cloud classification with NOAA/AVHRR.

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Towards the operational cloud classification in Finland

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  1. Towards the operational cloud classificationin Finland Otto Hyvärinen COST 722 Expert Meeting, Helsinki, 9 June 2004

  2. Contents • Cloud classification work with NOAA/AVHRR • in FMI • in Nowcasting SAF (PPS) • Problems • Future plans

  3. FMI approach to cloud classification with NOAA/AVHRR • The statistical pattern recognition approach • Collect a lot of training data • Approximate posterior probabilities with neural networks • Use a principled way of handling the uncertainty • No physics, only data! • Different models for day, night and twilight • Unfortunately, the development has stalled...

  4. 20 September 2001, 5:54 UTC

  5. Cloud Classification

  6. Goodness of Cloud/Surface Separation

  7. Nowcasting SAF approachwith NOAA/AVHRR • Developed mostly in SMHI • Traditional thresholding • Thresholds computed with the help of the radiative transfer models (RTTOV) • Uncertainty handled more ad hoc

  8. An example from 8 June 2004, 06:20 UTC Cloud Mask Cloud Classification

  9. How do they compare? • Comparison against SYNOP observations of total cloudiness All stations Stations from "the training area"

  10. Problems? • Common problems • Twilight! • AVHRR • FMI problems • no physics  should explore RTMs • Nowcasting SAF problems • bad decision making methods  should explore pattern recognition methods

  11. Towards future • Is Nowcasting SAF method for AVHRR "good enough" for us? • From AVHRR to MODIS, VIIRS, etc • how to make this as least painful as possible? • SEVIRI, how useful is it in Finland, really? • From the satellite cloud classification to the cloud analysis • how to combine remote sensing and in-situ observations with the model data to real 3D analysis of clouds, fog, and visibility?

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