Modification of a tropical storm tracking algorithm for extra-tropical cyclone detection

• Other Authors: Adams, Ryan (author), Neale, Richard (contributor), Bukovsky, Melissa (contributor), Collins, Nancy (contributor), Sossa, Awolou (contributor)
• Format: Manuscript
• Language: English
• Published: 2015
• Subjects: North Atlantic
• Online Access: http://nldr.library.ucar.edu/repository/collections/SOARS-000-000-000-455; https://doi.org/10.5065/y27r-7328

Extra-tropical cyclones are the main source of weekly weather variability across much of the middle latitudes and are often associated with damaging winds, coastal erosion, and significant precipitation. Under the right dynamic and thermodynamic conditions, these cyclones may rapidly intensify. This rapid intensification is called "bomb" cyclogenesis, and is particularly hazardous due to its low predictability and associated weather hazards. Using six-hourly Community Atmosphere Model (CAM 5.0) simulation output with a 0.25°x0.25° resolution for 1979-2006, an objective-based approach was implemented to modify a Geophysical Fluid Dynamics Laboratory tropical cyclone tracking algorithm to detect mid-latitude cyclones. The modification of the algorithm will be useful for future analyses based on extra-tropical cyclone climatology assessment. Systematically adjusting the algorithm thresholds reveal the sensitivities of tropical cyclone track density to each parameter. Increasing the radial distance threshold for a tropical cyclone at time t0 to the same cyclone at t1 reduces the Atlantic tropical cyclone storm count and deviates the Atlantic basin tropical storm track density. Additionally, decreasing the cyclone lifespan requirement from 3 days to 1 day increases tropical storm count globally and is more characteristic of storms traversing the North Atlantic in extra-tropical transition.