A ferry carrying more than 600 passengers sank in the Java Sea between the
island of Java and Borneo just before midnight on December 29, 2006,
during high winds and rough seas. On January 1, 2007, a plane carrying
more than 100 people crashed on its flight over the Java Sea; high winds
and turbulent weather are being investigated as possible causes. The
origin of surges of deadly winds in this usually relatively calm region
is poorly monitored and understood. However, ocean winds data from NASA's
QuikScat satellite show potential for helping alleviate such deficiencies.
Data obtained from QuikScat on December 30 and January 1 shed new insights
into the atmospheric conditions at the time of these incidents. QuikScat
data are available in near real time to operational weather forecasting
agencies around the world. The data from December 30 and January 1
observed that the strong winds in the Java Sea originated from the surge
of a strong winter monsoon from the Asian continent. The monsoon winds
blew south across the South China Sea and deflected eastward after they
crossed the equator due to the rotation of Earth. The winds strengthened
as they were channeled through the land masses of Indonesia. The winds in
the Java Sea remained strong through January 1, 2007. Associated with the
eastward winds, twin cyclones (a counter-clockwise circulation in the
Northern Hemisphere and a clockwise circulation in the Southern
Hemisphere) were also observed by QuikScat; the stronger one was south of
the equator (summer hemisphere) between Java and Australia, and a weaker
one was north of the equator (winter hemisphere) west of Borneo. In this
image from January 1, the different colors denote different wind speeds.
White arrows are wind vectors showing both direction and speed.
The large-scale, broad and simultaneous observations by QuikScat make it
possible to put the local weather into the context of the large-scale
circulation, and confirm one of the assumptions that links the cold surge
of the Asian monsoon with tropical cyclones in the western Pacific.
QuikScat, managed by JPL, measures ocean surface wind/stress by sending
radar pulses to the surface and measuring the strength of the signals
returned.
QuikScat Background
NASA's Quick Scatterometer (QuikScat) spacecraft was launched from
Vandenberg Air Force Base, California on June 19, 1999. QuikScat carries
the SeaWinds scatterometer, a specialized microwave radar that measures
near-surface wind speed and direction under all weather and cloud
conditions over the Earth's oceans. More information about the QuikScat
mission and observations is available at http://winds.jpl.nasa.gov.
QuikScat is managed for NASA's Science Mission Directorate, Washington,
DC, by NASA's Jet Propulsion Laboratory, Pasadena, CA. JPL also built the
SeaWinds radar instrument and is providing ground science processing
systems. NASA's Goddard Space Flight Center, Greenbelt, MD, managed
development of the satellite, designed and built by Ball Aerospace &
Technologies Corp., Boulder, CO. The National Oceanic and Atmospheric
Administration has contributed support to ground systems processing and
related activities.