NASA and two Japanese government agencies are
collaborating on a snowfall study over Wakasa Bay, Japan.
Using NASA’s Earth Observing System Aqua satellite, research
aircraft and coastal radars to gather data, the joint effort
is expanding scientific knowledge about where precipitation
falls.
Until now, the north Pacific’s contributions to the global
hydrologic cycle have been difficult to quantify.
Precipitation measurements by satellite over open water are
very important, because there are very few other ways to
obtain the data. Snowfall is particularly difficult to
measure from space even over the relatively uniform
background of the ocean. New satellite instruments, that can
detect precipitation over water, will give scientists data
to help interpret how the hydrology of the Pacific Ocean
impacts the U.S. and the world.
The Wakasa Bay Field Campaign is a combined research effort
among NASA, the National Space Agency of Japan (NASDA), and
the Japanese Meteorological Research Institute (MRI). The
campaign began January 3 and runs through February 14.
“These experiments are critical to understanding whether the
current El Nino event, for instance, actually increases
global precipitation or merely redistributes it between land
and ocean regions,” said Tom Wilheit, Mission Scientist from
Texas A&M University.
Wakasa Bay, located North of Osaka on the Sea of Japan, is
known for its diverse weather in winter months. Ranging from
extreme cold, that brings Siberian air and accompanying snow
into the region, to fast moving extra-tropical low pressure
systems, that consist primarily of rain at the surface, but
originating as snowfall at higher altitudes.
A NASA P-3 Orion aircraft, from Wallops Island, Va., is
flying over the bay and collecting data on snowfall and
rainfall to compare to data being gathered by the Aqua
satellite orbiting over the same area. The aircraft payload
consists of five microwave sensors, each capable of uniquely
observing precipitation and cloud properties.
On board Aqua is a Japanese-built Advanced Microwave
Scanning Radiometer-Earth Observing System (AMSR-E)
instrument. “With AMSR-E on Aqua, we’re able to extend the
high quality precipitation measurements from the Tropical
Rainfall Measuring Mission satellite to beyond the tropics,
in fact into both the mid-and high latitudes,” said Claire
Parkinson, Aqua Project Scientist at NASA’s Goddard Space
Flight Center, Greenbelt, Md.
Some of the measurements will also be used for another field
campaign concerning sea ice in the Sea of Okhotsk and to
compare with data from the AMSR instrument aboard the
Japanese ADEOS-II satellite.
The Wakasa Bay experiment is designed to test the
calculations and methods that scientists use to process
satellite data. The P-3 Orion observations will be used to
get precise values for the cloud and precipitation
properties, such as the size distribution of the ice
particles or raindrops, that are currently assumed in the
satellite calculations. By replacing the assumed data with
precise observations from the P-3, scientists can determine
the accuracy of the Aqua AMSR-E rainfall and snowfall
estimates.
“This mission will be helpful in understanding the north
Pacific, because there is simply no place in this vast
stretch of ocean where surface observations can be taken.
Despite its remoteness, the ocean’s size makes it an
important player in the global hydrologic cycle that must be
properly quantified to make progress in the global sense,”
said Christian Kummerow, Atmospheric Scientist at Colorado
State University, Boulder, Co., one of the leaders of this
mission.
NASA’s Aqua satellite was launched on May 4, 2002. The Aqua
mission provides a multi-disciplinary study of the Earth’s
atmospheric, oceanic, cryospheric, and land processes and
their relationship to global change.
For more information and images, see:
http://www.gsfc.nasa.gov/topstory/2003/0122japansnow.html
Experiment website:
http://rain.atmos.colostate.edu/Wakasa
For the Aqua website:
For the AMSR-E instrument website:
