2007: Simulation of recent multi-decadal increase of Atlantic hurricane activity using an 18-km regional model

• Main Authors: R. Knutson, Joseph J. Sirutis, Stephen T. Garner, Isaac M. Held, Robert, E. Tuleya
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.75.2146; http://www.gfdl.noaa.gov/~ih/papers/bams_hurricanes.pdf

A new 18-km-grid regional model successfully reproduces the observed multidecadal increase and interannual variations of Atlantic hurricane activity since 1980, using large-scale interior nudging toward the NCEP reanalysis. H urricane activity in the Atlantic basin increased markedly in the years 1995– 2000, compared with levels in the 1970s and 1980s. For example, the accumulated cyclone energy (ACE) index in the Atlantic has been above the 1951–2000 median for all years from 1995 to 2005 except for the El Niño years of 1997 and 2002 (e.g., Bell et al. 2006). The increase in activity since the early 1980s has been confirmed using homogenized satellite-based records (Kossin et al. 2007). Two recent seasons (2004 and 2005) have been exceptionally active in terms of U.S. landfalling hurricanes (particularly for the Florida and the Gulf Coast regions), compared to typical activity levels in recent decades (Landsea 2005). In this report we introduce a new regional atmospheric model designed to simulate full seasons of tropical cyclone (TC) activity in the Atlantic. By testing the model against observed interannual variability and trends, we hope to � Top: model outgoing longwave radiation snapshot (W m –2) illustrating scales of disturbances. Bottom: annual number (Aug–Oct) of North Atlantic basin hurricanes (1980–2005). See figures 2 and 5 for more information.