NASA Global Hawk Completes Atmospheric Rivers Study
A NASA Global Hawk aircraft completed the third and final flight of the Winter Storms and Pacific Atmospheric Rivers, or WISPAR, field campaign on March 10. The three long-duration flights over the Pacific Ocean explored atmospheric rivers, arctic weather, and collected targeted observations designed to improve operational weather forecasts.
The National Oceanic and Atmospheric Administration-led WISPAR airborne campaign that began Feb. 11 was focused on improving scientists’ understanding of how atmospheric rivers form and behave and to evaluate the operational use of unmanned, high-altitude aircraft for investigating these phenomena. This research is also designed to assist NOAA in potentially conducting offshore monitoring of atmospheric rivers to aid in future weather predictions.
Atmospheric rivers are narrow regions in Earth’s atmosphere that transport large amounts of water vapor across the Pacific Ocean or other regions. Aptly nicknamed “rivers in the sky,” they can transport enough water vapor in one day, on average, to flood an area the size of Maryland one foot deep or about seven times the average daily flow of water from the Mississippi River to the Gulf of Mexico.
An automated dropsonde system, developed for NOAA by the National Center for Atmospheric Research, was installed on NASA’s Global Hawk for this study. When dispensed from the aircraft, a sonde – about the size of a paper towel roll – collects temperature, relative humidity, wind and other readings as it descends through an atmospheric river or other weather feature.
“The experiment was very successful in evaluating the combined capabilities of the dropsonde system on the Global Hawk and exploring potential scientific and operational applications for NOAA,” said Gary Wick, a physicist from the Physical Sciences Division of the NOAA Earth System Research Laboratory, Boulder, Colo. "I was very impressed with the ability and willingness of the NASA team to modify the flight plans and scheduled drop locations in real time."
Also aboard the Global Hawk was the High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer, or HAMSR, an advanced water vapor sensor. Developed by NASA’s Jet Propulsion Laboratory in Pasadena, Calif., HAMSR analyzes the heat radiation emitted by oxygen and water molecules in the atmosphere to determine their density and temperature.
The HAMSR instrument operates at microwave frequencies that can penetrate clouds, enabling it to determine temperature, humidity and cloud structure under all weather conditions. This capability is critical for studying atmospheric processes associated with bad weather, like the conditions present in atmospheric river events.
"HAMSR worked flawlessly during the WISPAR campaign and was essentially operating autonomously, with no intervention required during the flights," said HAMSR principal investigator Bjorn Lambrigtsen. "The real-time data display capability provided situational awareness and was used to assist in
executing the flights, as was also done in the previous GRIP hurricane mission. The HAMSR data will be used by NOAA and JPL scientists to investigate the atmospheric river phenomenon."
Flying from NASA’s Dryden Flight Research Center at Edwards, Calif., the unmanned Global Hawk took off on the first atmospheric rivers flight on Feb. 11, landing 20 hours later. During the flight to investigate atmospheric rivers in the Pacific, 37 dropsondes were dispensed, the first use of a dropsonde system on the Global Hawk unmanned aircraft. The second flight of the series, a 24-hour winter storm reconnaissance mission that landed March 4, deployed 70 dropsondes.
The WISPAR experiment concluded March 10 with a 25-hour flight that extended into the Arctic polar vortex and reached 85 degrees north latitude. Another 70 dropsondes were deployed on the final flight, bringing the total to 177 dropsondes that were dispensed over the three flights.
NASA Dryden Flight Research Center