Northern Hemisphere tropical cyclone activity

Northern Hemisphere tropical cyclone activity

[1] Recent historical Northern Hemisphere (NH) tropical cyclone (TC) inactivity is compared with strikingly large observed variability during the past three decades. Yearly totals of the combined active-basin NH accumulated cyclone energy (ACE) are highly correlated with boreal spring seasurface temperature (SST) in the North Pacific Ocean and are representative of an evolving dual-gyre, trans-...

Multiple Indices of Northern Hemisphere Cyclone Activity, Winters 1949–99

The National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis is used to estimate time trends of, and analyze the relationships among, six indices of cyclone activity or forcing for the winters of 1949–99, over the region 208–708N. The indices are Eady growth rate and temperature variance, both at 500 hPa; surface meridional temperature gradie...

01 Southern Hemisphere Tropical Cyclone Climatology

Cluster analysis of tropical cyclone tracks in the Southern Hemisphere

A probabilistic clustering method is used to describe various aspects of tropical cyclone (TC) tracks in the Southern Hemisphere, for the period 1969–2008. A total of 7 clusters are examined: three in the South Indian Ocean, three in the Australian Region, and one in the South Pacific Ocean. Large-scale environmental variables related to TC genesis in each cluster are explored, including sea su...

A Tropical Mechanism for Northern Hemisphere Deglaciation

We investigate the role of the tropics in the melting and reforming of the Laurentide ice sheet on glacial timescales using an atmospheric general circulation model. It is found that warming of tropical sea surface temperatures (SST) from glacial boundary conditions, as observed at the end of glacial periods [Bard et al., 1997, Lea et al., 2000, Nurnberg et al., 2000], causes a large increase i...