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'Twas the week before Christmas, and though Santa may have been busy prepping his sleigh for flight, the staff at National Oceanic and Atmospheric Administration (NOAA)'s Aircraft Operations Center (AOC) in Tampa, Florida, found time to give U.S. Geological Survey (USGS) scientists a tour of their facility. The tour participantsmembers of the Extreme Storm Team at the USGS Florida Integrated Science Center office in St. Petersburg, who routinely process large amounts of data as part of their workwere particularly interested in better understanding the mechanics of acquiring such data with instrumented aircraft.
NOAA houses many of its research aircraft in a hanger at MacDill Air Force Base in Tampa, only a short drive from the USGS office in St. Petersburg. The tour group was lucky in that two of the three major aircraft used for hurricane research were onsite and available for inspection. Jack Parrish, chief science officer for the Gulfstream IV-SP (G-IV), the high-altitude reconnaissance jet, took time from his busy schedule to lead the in-depth tour. Unfortunately, the G-IV was offsite getting refurbished with new instrumentation, and so we had a virtual tour of that aircraft.
The workhorse of the NOAA hurricane-research fleet is the Lockheed WP-3D Orion (P-3), a large four-engine turboprop aircraft that was originally designed for antisubmarine warfare. We received a detailed tour of the P-3, tail number NR43F, also known as Miss Piggy. The plane was undergoing modifications from its hurricane-research configuration to an air-chemistry configuration to be flown over the U.S. west coast in the spring.
Because of the extensive modifications, which are mostly one-of-a-kind applications, changes to the P-3 do not require Federal Aviation Administration (FAA) approval for flying but are approved locally. The G-IV, in contrast, must conform to more standard configurations, and its modifications must receive FAA approval. The P-3 has two barber-pole samplers (named for their red-and-white stripes) protruding from the front of the aircraft, a tail Doppler radar, and several unique-looking instruments hanging from the wing.
One of the standard procedures that NOAA performs on its P-3 missions is sampling dust from the atmosphere. Because most of these missions are in the Caribbean and the Atlantic, African dust makes up a sizable component of the samples. African dust is of particular interest to USGS scientists at St. Petersburg, where a group is studying its relation to coral mortality (see URL http://coastal.er.usgs.gov/african_dust/). Anecdotal reports from the 2007 missions indicate that the dust in 2007 was less dense but lasted longer than in previous years. Whatever the reasons, everyone was glad that the 2007 hurricane season was not as busy as previous years.
The primary method for gathering data from the aircraft for profiles of the atmosphere is the dropsonde, a weather-reconnaissance device that is dropped from an aircraft and measures atmospheric conditions as it falls to the ground. Typically, a dropsonde carries pressure, temperature, and humidity sensors and a global-positioning-system (GPS) receiver. The measurements are relayed to a computer in the aircraft by radio transmission. AOC has specialized in calibrating its dropsondes both before and during flights. Shrink-wrapping the dropsondes and connecting their electronics inflight are some of the calibration techniques AOC has developed to provide more accurate measurements.
The twin-engine Twin Otter is the aircraft that was used by the USGS Extreme Storm Team to fly some of its early photography and lidar (light detection and ranging) missions. The aircraft is particularly suitable for such missions because it has a slow cruising speed and can take off and land on short runways. NOAA's Twin Otter has a large bubble window just forward of the wing, which is designed for marine-mammal surveys; this bubble window may have added a slight distortion to some of the early USGS still photographs.
The members of the Extreme Storm Team were grateful for the hospitality extended by the NOAA AOC staff for our Christmas tour and extends wishes to everyone for a good and peaceful New Year.
in this issue:
Tour of NOAA Aircraft Facility
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