On the Collapse of the Surface Easterly Wind in the Eastern Equatorial Pacific in the 2015 El Nino

David Halpern, NASA Jet Propulsion Laboratory, Pasadena, CA, United States
Wind speed and direction measurements were recorded at 10-m height by the NASA SeaWinds scatterometer instrument on the NASA QuikSCAT satellite (June 1999 – November 2009), the ESA Advanced Scatterometer (ASCAT-A) instrument on the first EUMETSAT Meteorological Operational (MetOp-A) satellite (May 2007 – present), and the NASA RapidScat instrument on the International Space Station (September 2014 – present). The composite longitudinal distributions of monthly-averaged surface vector winds along the equator were determined during the four El Nino and four La Nina events that had occurred since the 1997-1998 El Nino super-event. West of 150°W the average strength of the surface westward wind speed in El Nino was more than 2 m s-1 smaller compared to that in four La Nina events. No such reduction in westward wind speed occurred east of 150°W. We will discuss the response of surface westward winds along the equator in the 2015 El Nino event, which has been predicted to become a super-event. Additionally, we will describe the response of MISR eastward winds in the upper troposphere in the 2015 El Nino event.