Robert DeMaria

 Motivation  Objective  Data  Center-Fixing Method  Evaluation Method  Results  Conclusion

 Only west Atlantic has routine hurricane hunter aircraft for finding storm centers  Satellite data used subjectively to find centers across the globe  Improvements to accuracy in real- time highly desirable sos.noaa.gov/Education/tracking.html

 Geostationary satellites produce Infrared(IR) every 15 Minutes  Forecast produced every 6 hours  Due to time constraints, most of these images are unused  Automatic method for estimating tropical cyclone location is highly desirable

 Tropical cyclones are roughly circular  Use Circular Hough Transform (CHT) to produce estimate for tropical cyclone location by finding circles in IR imagery  Compare accuracy to National Hurricane Center real-time center-fix

 2D Image of Temperature ◦ Created every 15 minutes

 A-Deck: Real-time estimate of position, velocity, wind speed, etc. ◦ Updated every 6 hours  Best-Track: Improved a-deck data available after end of season

 Find a-deck position ◦ Given the time an IR image was created, look up most recent a-deck information and extrapolate position to IR image time  Subset of IR image used ◦ Center image on a-deck position ◦ Image reduced to area around storm/area around eye ◦ Background removed from cloud shield using temperature threshold

 IR after subsect & thresholding:

 Laplacian of image performed to find edge pixels

 Circular Hough Transform performed for a range of radii on image  Gaussian fit performed on accumulation space to produce center location

 For each time in best-track, find most recent IR image  Estimate if eye is present in image ◦ If it is then perform center-fix searching for radii roughly the size of an eye ◦ If not, perform center-fix searching for radii roughly the size of the entire storm  Error calculated as CHT center-fix distance from best-track location  Compare error to that of the a-deck position

Katrina 08/29/ Earl 09/02/ Charley 08/13/ Katrina 08/25/ Ericka 09/02/ Sandy 10/19/ No Eye Cases Eye Cases

 Charley 2004 – Very small but intense hurricane  Katrina 2005 – Classic large, intense hurricane  Ericka 2009 – Very disorganized weak tropical cyclone, did not make it to hurricane strength  Earl 2010 – Strong hurricane in higher latitudes  Sandy 2012 – Unusually large but only moderate strength, non-classical hurricane structure

 Mean a-deck error: 42 km  Mean CHT error: 91 km  Bias X: 6 km  Bias Y: 8.5 km  Bias Explained by Parallax

 Strong Circular Eye Greatly Improves Accuracy ◦ Eye Mean Error: 54 km ◦ No Eye Mean Error: 127 km ◦ Strong circular eyes are fairly rare

 Did not improve real-time center fix  Rotational center may not be in center of cloud features: CHT may not be well suited to large-scale images  CHT may be useful when an eye is present

 Use time-series information to improve  Combine with information about vertical shear  Improve eye estimation technique