Analysis of the origins of east Pacific easterly waves

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Wednesday, 5 February 2014
Hall C3 (The Georgia World Congress Center )
Ernesto W. Findlay, University At albany, Albany, NY; and A. V. Rydbeck and E. D. Maloney

The east Pacific Ocean is the second most active hurricane basin in the world. According to the National Hurricane Center, approximately 70% of tropical cyclones in the east Pacific are said to be seeded by African easterly waves. However, this statistic assumes continuous propagation of easterly waves from the Atlantic to the east Pacific. This study focuses on investigating the origins and tracks of easterly waves in the east Pacific during the months of June-November when EWs are most active. It is hypothesized in this study that most of the easterly waves (EWs) in the east Pacific are not linked to EWs originating in Africa but are initiated in-situ. The bight of Panama appears to be a climatologically favorable environment for the development of easterly waves due to the low-level cyclonic flow and precipitation maximum. Easterly waves are analyzed using lag correlation and composites plots of 2-10 day filtered meridional winds and precipitation from NCEP/NCAR reanalysis and TRMM, respectively. From these analyses, we compare the relationship between easterly waves in the Atlantic to those in the east Pacific. A limited WRF simulation was also utilized to compare the location and track of easterly waves to observations during August 2005. Composites and lag correlations of easterly waves support the idea that most easterly waves are generated in the east Pacific rather than initiating in Africa, as the analysis does not support the propagation of easterly waves across Central America and Mexico.