Researchers aboard the NOAA Gulfstream IV aircraft will begin flying over the Pacific Ocean off the U.S. West Coast this week to measure air pressure, temperature, humidity, wind speed and direction to help better understand atmospheric rivers.

Atmospheric rivers are narrow conveyor belts of water vapor that can extend thousands of miles. They can provide beneficial water supply and snowpack to the West Coast as well as create conditions for dangerous floods that affect lives and property.

"We will be looking at the structure and evolution of atmospheric rivers,” said lead researcher Chris Fairall of NOAA’s Earth System Research Laboratory (ESRL). “One big atmospheric river can be the difference between drought and flood at a given location. Water and pollution managers, farmers, and skiers all want good precipitation forecasts but the uncertainty is dominated by intensity and landfall location of atmospheric rivers."

"So far this winter, the general weather circulation pattern is causing atmospheric rivers to miss California, which is exacerbating the drought," said researcher Allen White of ESRL. "We are expecting an atmospheric river will hit California this weekend (February 8-9), and we'll be flying through this river and another that is forming over the Pacific."

Researchers from ESRL and Scripps Institute for Oceanography are studying atmospheric rivers to help provide better information for earlier extreme weather forecasts. The scientists are also looking at how climate change may be affecting atmospheric rivers.

Aboard the G-IV, researchers will release small parachuted devices, called dropsondes, across an atmospheric river over the Pacific Ocean. The dropsondes measure atmospheric conditions, such as pressure, temperature, humidity, wind speed and direction, and transmit the information back to the aircraft where a flight scientist uses it to guide the mission. After the dropsonde data is analyzed and processed, the information will be put into a standard format established by the World Meteorological Organization and provided to NOAA’s National Hurricane Center for inclusion in global and local-scale weather prediction models.

The G-IV will also use its tail Doppler radar to map precipitation and wind. The radar data were successfully incorporated into weather prediction models for the first time during the 2013 Atlantic hurricane season. NOAA’s G-IV is based at the NOAA Aircraft Operations Center, located at MacDill Air Force Base in Tampa, Fla.

Results from this study will help guide atmospheric river research for the upcoming CalWater 2 experiment, which begins in 2015 and will use land-based stations and a research ship as well as multiple aircraft.

Posted: February 3, 2014