Fig. 1: Average for the Month starting November 8, 2014

Fig. 2: Average for the Month starting November 7, 2015

Fig. 3: Anomaly Winds for November, 2015; RapidScat
Click on an image above for larger view

While El Niño events have a significant impact on the entire Earth System, they are most easily visible in measurements of sea surface temperature (SST), sea surface height (SSH) and ocean winds near the surface. In fact, the precursor and the main driver of El Niño events is manifested in the weakening of the normally westward blowing trade winds, or even their complete reversal to blow from west to east, in the Western and Central tropical Pacific.

These images show ocean winds near the surface as observed by NASA's ISS-RapidScat on the International Space Station. ISS-RapidScat was launched on Sept. 21, 2014, and began providing high-quality data a couple of weeks later. The RapidScat instrument is a speedy and cost-effective replacement for NASA's QuikScat satellite, which monitored ocean winds for 10 years, providing essential measurements used in weather predictions and climate monitoring. QuikScat's measurements were so essential that when the satellite stopped collecting wind data in late 2009, NASA was challenged to quickly and cost-effectively conceive of a replacement. To interactively explore the data, visit http://mwsci.jpl.nasa.gov/rapidscat/.

The monthly average winds for November 2014 are shown in Fig. 1, while the monthly average winds for November 2015 are shown in Fig. 2. The 2015 anomalous winds (with respect to 2014) are shown in Fig. 3. In all cases, the colors represent the wind speed (or speed differences), while the vectors illustrate the direction of the average (or anomaly) mean wind components. The El Niño signal is very clearly evident in the eastward blowing anomalous winds observed in the tropical western and central Pacific, as shown in Fig. 3. The El Niño signal is also seen in the anomalous stronger convergence into the tropical eastern Pacific, as evidenced by the stronger winds moving toward the equator observed in this region.

RapidScat measures Earth's ocean surface wind speed and direction over open waters. The instrument's data on ocean winds provide essential measurements for researchers and scientists to use in weather predictions, including hurricane monitoring. The NASA instrument arrived at the International Space Station (ISS) on Sept. 23, 2014, providing a new resource for tracking and studying storms ranging from tropical cyclones to nor'easters. RapidScat has kept busy in 2015's already active Southern Hemisphere hurricane season and the Northern Hemisphere's winter storm season.

For more information on RapidScat, visit http://winds.jpl.nasa.gov/missions/RapidScat/ and http://www.nasa.gov/rapidscat.