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Tropical Storm Gabrielle (NASA-GSFC, NOAA GOES)

Status Report: 01-306

NASA hurricane researchers study intensity of tropical storm Gabrielle, mission slowed by bad weather

Researchers in NASA’s Convection and Moisture Experiment (CAMEX) were delayed by bad weather from Gabrielle as it crossed Florida over the weekend.  Even with the hurdles, the scientists were able to gather valuable information about the formation, development and winding-down of tropical storm Gabrielle.

The CAMEX team had planned a flight into Gabrielle on Friday, Sept. 14 as the storm gathered strength in the Gulf of Mexico and moved toward Florida’s west coast. However, they had to scrub that flight because of high winds and heavy rains created by Gabrielle in the Jacksonville area.  However, the ground-based component of CAMEX had a notable success in documenting the storm’s landfall.

Two truck-mounted radars and a microwave profiling system left their stations in the Florida Keys, and with the help of the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division (HRD) scientists positioned themselves near Venice, Florida ahead of the storm on Friday. It was the first time that a mobile 5 cm Doppler radar has intercepted a land falling tropical cyclone. The radar observed winds just barely below hurricane force but was able to acquire data despite the buffeting from winds and torrential rain.

Gabrielle hit Florida’s west coast Friday morning with 70-mile per hour winds and moved across the state Friday afternoon and evening — still packing high winds and heavy rain. She spawned tornadoes, knocked down trees and interrupted power

to over 500,000 Floridians while dumping several inches of rain that resulted in flooding. Gabrielle exited into the Atlantic during the early morning of Saturday Sept. 15.

On Saturday, the specially equipped DC-8 — a converted passenger airliner — was the only NASA aircraft to fly. It flew in coordination with a NOAA P-3 Orion aircraft with HRD scientists who partner with NASA scientists in CAMEX. NASA’s ER-2, a single-pilot, high-flying jet could not take off or land Saturday because of high crosswinds.

A team of approximately 30 researchers were onboard the DC-8 and they used a variety of instruments to capture data about Gabrielle. The flight departed Jacksonville at 2:13 p.m. EDT, moved south-southwest and then turned east to fly over central Florida and out over the Atlantic to catch up with Gabrielle.

During the almost seven hour mission, the CAMEX team flew three separate figure-four patterns into the storm and along the outer edges to gather moisture and convection data — the P-3 from 14,000 - 20,000 ft and the DC-8 from 31,000 - 39,000 ft.  The DC-8 returned to Jacksonville at 9:03 p.m. EDT Saturday. The objective was to learn why Gabrielle failed to re-intensify despite being over very warm waters of the Gulf Stream. The main culprit appeared to be the unusually dry air and strong wind shear noted by the DC-8 at high levels over the storm.

The ER-2 took off Sunday, Sept. 16 at 3:30 p.m. EDT to fly in coordination with a NOAA research aircraft in and around Gabrielle as she kept moving northeastward approximately 250 miles off the North Carolina coast. The high-flying ER-2 returned at 8:30 p.m. EDT after flying at altitudes of approximately 60,000 feet to place dropsondes — devices used to measure the vertical profile of winds, temperature and moisture — at specific points on the perimeter and at the center of the diminishing storm. It also gathered remote sensing measurements that are similar to weather information gathered from satellites, and this data will be used in future hurricane models. The DC-8 did not fly on Sunday due to equipment problems.

The CAMEX mission unites researchers from 10 universities, five NASA centers and the National Oceanic and Atmospheric Administration (NOAA). The study is part of NASA's Earth Science enterprise to better understand the total Earth system and the effects of natural and human-induced changes on the global environment.