|
NASA
Sees Repeating La Niña Hitting its Peak
01.18.12-Jet
Propulsion Laboratory NASA-La Niña, "the diva of
drought," is peaking, increasing the odds that the Pacific Northwest
will have more stormy weather this winter and spring, while the
southwestern and southern United States will be dry.
Sea surface height data
from NASA's Jason-1 and -2 satellites show that the milder repeat of last
year's strong La Niña has recently intensified.
 The latest
image of sea surface heights in the Pacific Ocean from NASA’s Jason-2
satellite shows that the current La Niña is peaking in intensity. Yellows
and reds indicate areas where sea surface height is higher than normal
(due to warm water), while blues and purples depict areas where sea
surface height is lower than normal (due to cool water). Green indicates
near-normal conditions. Image credit: NASA/JPL Ocean Surface Topography
Team
The image is based on the
average of 10 days of data centered on Jan. 8, 2012. It depicts places
where the Pacific sea surface height is higher than normal (due to warm
water) as yellow and red, while places where the sea surface is lower than
normal (due to cool water) are shown in blues and purples. Green indicates
near-normal conditions. The height of the sea surface over a given area is
an indicator of ocean temperature and other factors that influence
climate.
This is the second
consecutive year that the Jason altimetric satellites have measured
lower-than-normal sea surface heights in the equatorial Pacific and
unusually high sea surface heights in the western Pacific.
"Conditions are ripe
for a stormy, wet winter in the Pacific Northwest and a dry, relatively
rainless winter in Southern California, the Southwest and the southern
tier of the United States," says climatologist Bill Patzert of JPL.
"After more than a decade of mostly dry years on the Colorado River
watershed and in the American Southwest, and only two normal rain years in
the past six years in Southern California, low water supplies are lurking.
This La Niña could deepen the drought in the already parched Southwest
and could also worsen conditions that have fueled recent deadly
wildfires."
NASA will continue to
monitor this latest La Niña to see whether it has reached its expected
winter peak or continues to strengthen. A repeat of La Niña ocean
conditions from one year to the next is not uncommon: repeating La Niñas
occurred most recently in 1973-74-75, 1998-99-2000 and in 2007-08-09.
Repeating La Niñas most often follow an El Niño episode and are
essentially the opposite of El Niño conditions. During a La Niña
episode, trade winds are stronger than normal, and the cold water that
normally exists along the coast of South America extends to the central
equatorial Pacific.
La Niña episodes change
global weather patterns and are associated with less moisture in the air
over cooler ocean waters. This results in less rain along the coasts of
North and South America and along the equator, and more rain in the far
Western Pacific.
The comings and goings of
El Niño and La Niña are part of a long-term, evolving state of global
climate, for which measurements of sea surface height are a key indicator.
Jason-1 is a joint effort between NASA and the French Space Agency, Centre
National d'Études Spatiales (CNES). Jason-2 is a joint effort between
NASA, the National Oceanic and Atmospheric Administration, CNES and the
European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).
JPL manages the U.S. portion of both missions for NASA's Science Mission
Directorate, Washington, D.C.
|
