A Comparison of Arctic and Atlantic Basin Cyclone Predictability from a Climatology and Case Study Perspective

• Main Author: Capute, Peyton
• Format: Text
• Language: English
• Published: Scholars Archive 2024
• Subjects: Arctic cyclone; numerical weather prediction; cyclone predictability; ensemble sensitivity analysis; Atmospheric Sciences; Meteorology; Arctic; Sea ice
• Online Access: https://scholarsarchive.library.albany.edu/etd/21; https://scholarsarchive.library.albany.edu/context/etd/article/1035/viewcontent/Capute_dissertation_Final_6August2024.pdf

Arctic cyclones (ACs) can transport warm, moist air into the Arctic region, which combined with strong winds may lead to rapid declines in sea ice during the summer. As a consequence, accurate sea ice predictions during the summer may rely on being able to predict cyclone-related wind speed and direction, which critically depends on the cyclone track and intensity. Despite this, there are relatively few studies that have documented the predictability of ACs during the summer, beyond a few case studies. In addition, there has been no extensive comparison of whether these cyclones are more or less predictable relative to comparable midlatitude cyclones, which have been studied in greater detail. The first part of this thesis creates a climatology of comparable, long-duration, intense Arctic and Atlantic basin cyclones to compare the predictability of Arctic and Atlantic position and intensity forecasts over a large number of cases using the Global Ensemble Forecast System Reforecast V2. Using standard deviation (SD) and root mean square error as a proxy for predictability, Atlantic cyclone position is characterized by higher predictability relative to comparable ACs, but intensity predictability is higher for ACs. In addition, storms in both basins characterized by low ensemble SD and predictability are found in regions of higher baroclinicity than storms characterized by high predictability. There appears to be little, if any, relationship between latent heat release and precipitable water and predictability. The source of position and intensity forecast variability of two Arctic and two Atlantic basin cyclones, similar to those analyzed in the climatology, is diagnosed using ensemble-based sensitivity analysis applied to Model for Prediction Across Scales ensemble forecasts. Results suggest that the position and intensity variability of these storms are largely associated with both upstream and downstream uncertainty of meso-scale features embedded within the larger-scale potential vorticity (PV) features, ...