Comparison of GOES Cloud Classification Algorithms Employing

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