NOAA GULFSTREAM-IV HURRICANE SURVEILLANCE JET TAKES ON PACIFIC WINTER STORMS TO IMPROVE FORECAST MODELS
Flying from Honolulu and Anchorage, Jet Also Conducts Ozone Transport Studies and Satellite Sensor Calibrations

Feb. 11, 2004 — In an effort to improve forecasts released 24-96 hours before a winter storm, NOAA has deployed its high-altitude hurricane surveillance Gulfstream-IV jet to collect atmospheric data for severe winter storms originating over the Pacific Ocean that will seriously impact the continental United States and Alaska. The jet is flying from temporary bases in Honolulu, Hawaii, and Anchorage, Alaska. (Click NOAA image for larger view of NOAA Gulfstream-IV jet in Anchorage, Alaska, during the 2003 Pacific winter storm mission. Click here for high resolution version, which is a large file. Please credit “NOAA.”)

To provide full coverage of the Pacific jetstream that affects weather patterns over the United States, an Air Force Reserve’s WC-130 aircraft is flying missions out of Honolulu in conjunction with the G-IV jet. Both aircraft are deploying dropwindsondes—small meteorological instruments that measure temperature, wind speed, humidity and surface pressure. The information is relayed in real time to the NOAA National Weather Service supercomputer, which incorporates it into the agency’s numerical prediction models.

“If you want to really know what the weather will be like two or three days ahead, you must get an accurate sense of what the weather is doing currently,” said Zoltan Toth, a research meteorologist at the NOAA Environmental Modeling Center in Camp Springs, Md. “The net result of the flights is a 48-hour targeted storm forecast that is as accurate as a 36-hour forecast. The increased forecast lead time is crucial for residents living in harm’s way.”

In its fourth year, the Winter Storm Reconnaissance Program has already seen up to a 20 percent increase in forecast accuracy on average. Accuracy for individual targeted events has been increased by as much as 60-80 percent in 24-96 hour forecasts during past missions.

This year’s program, operated by the NOAA National Weather Service, began Jan. 21 in Honolulu. The G-IV left Honolulu on Jan. 31 and began operations from Anchorage on Feb. 1, where it will remain until Feb. 27. It returns to Honolulu on Feb. 28; operations there will continue through March 14. Up to 465 dropwindsondes will be deployed and 155 flight hours flown during the program. (Click NOAA image for larger view of NOAA Gulfstream-IV jet. Please credit “NOAA.”)

The aircraft are deployed from one to four days in advance of a potential storm system in the Pacific that appears headed for either Alaska or the continental United States. “The Air Force Reserve’s WC-130 will fly out of Hawaii while the NOAA jet is in Anchorage, with both planes acting in tandem to capture data north and south of the jetstream simultaneously,” said Jack Parrish, meteorologist and program manager for the G-IV at the NOAA Aircraft Operations Center in Tampa, Fla. “The G-IV, with supplementary data from the WC-130, provides the most comprehensive data coverage collected in the environment of winter storms.”

The unique characteristics of the G-IV are being used to further NOAA’s knowledge of the environment in other ways as well. The NOAA Aeronomy Laboratory is conducting the Pacific Sub-tropical Jet Study 2004 to investigate the transport of ozone in the vicinity of the Pacific jetstream. Ozone is a gas that occurs both in the troposphere, where it affects climate and is a pollutant at the Earth’s surface, and stratosphere, where it is more abundant and absorbs much of the sun’s harmful ultraviolet radiation. Data from ozone-measuring instruments will be combined with the dropwindsonde data being gathered during the mission to help researchers unravel the jetstream’s complex effects on the atmosphere.

The study began in January during the G-IV’s flights in the mid-Pacific region north of Hawaii, and will resume in late February when the jet returns to Hawaii. The flights slice through the jetstream in the east-west direction to get a rare look at how ozone varies along the way. The dropwindsondes provide meteorological data that will be used to analyze the movements of the air.

“These data will be particularly valuable in studying ‘folds’ that occur in the atmosphere in the vicinity of the jet,” said David Parrish, principal investigator with the NOAA Aeronomy Laboratory in Boulder, Colo. “These folds can act as conduits for the exchange of air between the ozone-rich stratosphere and the troposphere, thereby strongly influencing ozone abundances in both regions.”

The mission should help scientists learn more about the factors that affect ozone abundances in the air that eventually arrives at the U.S. West Coast, which influences air quality in that region. Measurements have indicated that this ozone has been increasing in recent years; the 2004 study should provide insights into the natural and human-caused factors that underlie those observations.

A third mission for the G-IV crew over the Pacific involves validating and calibrating space-borne instrument measurements from the Special Sensor Microwave Imager/Sounder (SSMIS), launched recently for the Defense Meteorological Satellite Program. Once validated, these satellite measurements offer vertical soundings through the lower atmosphere of temperature and moisture over broad swaths of ocean and land as they orbit the Earth. These data in turn greatly help to initialize weather forecast models with accurate initial conditions.

NOAA’s G-IV jet, primarily used for hurricane surveillance, is based at the NOAA Aircraft Operations Center at MacDill Air Force Base in Tampa, Fla. AOC is part of the NOAA Marine and Aviation Operations, which includes civilians as well as officers of the NOAA Corps, the smallest of the nation’s seven uniformed services. NOAA Corps pilots and civilian meteorologists, flight and electronics engineers, and technicians are highly trained to operate in adverse weather conditions.

The U.S. Air Force Reserve’s C-130 “hurricane hunter” aircraft is operated by the 53rd Weather Reconnaissance Squadron based at Kessler Air Force Base in Biloxi, Miss. The fleet of C-130 aircraft are flown and crewed by Air Force reservists in support of the NOAA National Weather Service.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation’s coastal and marine resources. NOAA is part of the U.S. Department of Commerce.

Relevant Web Sites
NOAA Gulfstream-IV Jet

NOAA Environmental Modeling Center

NOAA Aeronomy Laboratory

Media Contact:
Jeanne Kouhestani, NOAA Marine and Aviation Operations, (301) 713-3431, ext. 220