Southwest Airlines has completed installing water-vapor sensing systems (WVSS-II) on 87 Boeing 737 aircraft as part of a multi-organization effort to improve aviation weather forecasting in the United States.
The water-vapor sensing initiative is a result of a partnership among Aeronautical Radio Incorporated (ARINC), the U.S. National Oceanic and Atmospheric Administration (NOAA) and SpectraSensors, Inc. the maker of the water-vapor sensng systems.
According to Southwest Airlines, the sensing system has the potential to improve weather forecasting by providing real-time and frequent humidity data when aircraft take off and land at airports throughout the U.S.
“Southwest’s meteorology team has always worked closely with ARINC and NOAA, and the WVSS-II project is symbolic of our strong reliance on each other,” says Rick Curtis, chief meteorologist for Southwest Airlines. “We are proud to be the only passenger airline currently participating in the project and look forward to the many ways WVSS-II will impact and improve both weather forecasting and the impact on airline operations.”
U.S. National Weather Service forecasters routinely use WVSS-II observations in their day-to-day operations. Monitoring the distribution of moisture in the atmosphere and how the moisture levels change with time play an integral role in forecast preparation.
Aviation forecasters rely on WVSS-II data to help determine location and timing of fog, cloud formation and dissipation, and altitudes of cloud ceilings. All of these factors are critical to determining safe conditions for aircraft travel, according to Southwest.
“Water vapor is the most rapid-changing and under-sampled element in the atmosphere,” says Carl Weiss, an aviation meteorologist for NOAA. “On the heels of a tumultuous weather year, WVSS-II is part of a larger initiative contributing to Weather Ready Nation, our initiative focused on building community resilience in the face of extreme weather events.”
Adds Weiss: “WVSS-II data upon take-offs and landings allow forecasters to monitor and stay on top of how moisture is changing in the atmosphere, specifically in severe weather situations when preparedness is especially important.”
The WVSS-II system, which is manufactured by SpectraSensors, Inc., measures water vapor in the atmosphere hundreds of times during an aircraft’s flight.
These measurements are automatically transmitted to ARINC’s headquarters in Annapolis in Maryland via the ARINC GLOBALink/VHFTM data link service.
Along with other aircraft weather data, the atmospheric moisture data are then forwarded in near real-time to the National Weather Service, which uses them to improve the accuracy of its computer-generated weather forecasts and severe weather warnings.
“The WVSS-II observations add a critical new piece of weather data to the forecasting puzzle,” says Jeannine Hendricks, ARINC’s manager for the WVSS program. “For the first time in aircraft operations, we are collecting water vapor data that measures the humidity in the air.
Adds Hendricks: “This has the potential to revolutionize weather forecasting ‒ especially when predicting thunderstorms, a significant weather occurrence for aviation.”
While weather balloons (previously the only method for capturing weather data) measure wind, temperature, and humidity data twice per day at certain locations, the WVSS-II water-vapor sensors gather humidity data throughout the day at multiple points across the U.S.
According to Southwest, the improved water vapor data will have a direct benefit in the accuracy of forecasts of precipitation and clouds, which will benefit the aviation community, its customers, and the general public.
Southwest Airlines plans to continue working with ARINC and NOAA, in conjunction with the National Weather Service, to expand WVSS-II installations on its aircraft fleet.
NOAA’s National Weather Service is the primary source of weather data, forecasts and warnings for the United States and its territories. NOAA’s National Weather Service operates the most advanced weather and flood warning and forecast system in the world.
ARINC Incorporated, which is owned by The Carlyle Group, provides communications, engineering and integration solutions for commercial and government customers worldwide and is particularly active in the aerospace industry.
Headquartered in Annapolis in Maryland and operating regional headquarters in London and Singapore, ARINC is certified to ISO 9001:2008 and AS9100:2009 Rev C standards.