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Comparison of GOES Cloud Classification Algorithms Employing Explicit and Implicit Physics

Comparison of GOES Cloud Classification Algorithms Employing Explicit and Implicit Physics. Richard L. Bankert and Cristian Mitrescu Naval Research Laboratory (NRL) Monterey, CA Steven D. Miller Cooperative Institute for Research in the Atmosphere (CIRA) Colorado State University

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Comparison of GOES Cloud Classification Algorithms Employing Explicit and Implicit Physics

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  1. Comparison of GOES Cloud Classification Algorithms Employing Explicit and Implicit Physics Richard L. Bankert and Cristian Mitrescu Naval Research Laboratory (NRL) Monterey, CA Steven D. Miller Cooperative Institute for Research in the Atmosphere (CIRA) Colorado State University Robert H.Wade Science Applications International Corporation (SAIC) Monterey, CA VALIDATION RESULTS • NRL GOES CLOUD CLASSIFIER (CC) • Implicit Physics • Supervised Learning • 1-Nearest Neighbor • Expert-Labeled Training Sets • Samples represented by features: spectral, textural, etc Percent (%) distribution of pixels within each CT algorithm type (columns) matched with CC class (rows) – columns sum to ~100% Percent (%) distribution of pixels within each CC class (rows) matched with CT algorithm type (columns) – rows sum to ~100% CC Daytime Classes Low/Liquid water: St, Sc, Cu Mid/Mixed phase: Ac, As, CuC High/Ice: Cs, Cc, Cb, CsAn* *CsAn: Deep Convection (Cs near Cb) Cirrus (Ci) Clear (Clr) Classifier Disagreement Example 16 Apr 2007 1700 UTC • CLOUD TYPE ALGORITHM (CT) • Explicit Physics • Cloud mask algorithm applied • Cloud phase tests • GOES-11 channel thresholds GOES-11 VIS GOES-11 IR CC Classification CT Classification CT Classes Liquid water Mixed (Supercooled water) Glaciated (Opaque Ice) Cirrus (Ci) Overlapping Clouds (OL) Clear (Clr) High clouds over low clouds (front) off CA coast CC: Mid-level clouds (As, Ac) – getting signals from both low and high clouds (no OL class) CT: Correctly classified as OL or at least getting Ci correct Final classification rule: If pixel is classified as Mid-level cloud by CC and OL or Ci by CT, pixel is classified as OL. DATA Other disagreements can be analyzed similarly to produce combined classifier that overcomes limitations of single algorithm.In addition, increased confidence can result from classifier agreements and indivdual classifier refinements can be further researched and tested. • NE Pacific region • GOES-11 data (5 channels) • Hourly (daytime) for one year

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