USGS Extreme Storm Team Receives Christmas Week Tour of NOAA Aircraft Facility


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USGS Extreme Storm Team Receives Christmas Week Tour of NOAA Aircraft Facility

By Dennis Krohn
March 2008

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Jack Parrish describes the capabilities of the P-3

Above: Jack Parrish, NOAA Aircraft Operations scientist, describes the capabilities of the P-3 to USGS scientists. The engine props vary in pitch to change the speed of the aircraft. The black pod on the bottom of the fuselage is downward-looking weather radar that is lowered away from the main aircraft body in flight for better aerodynamics. [larger version]

'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 participants—members 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 work—were 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.

Above left: NOAA's P-3 research aircraft with "barber-pole" probe protruding from its forward end. In the early days of aircraft research, the probe was used to sample the air in front of the bow wake of the aircraft. More recent instrumentation has shown that it is more practical to sample the air immediately adjacent to the aircraft. The "barber pole" has remained on the aircraft and serves mainly as a lightning rod. [larger version]

Above right: Dust-and-particulate-sampling apparatus hangs below the port wing of the NOAA P-3. Spare engines and props for the P-3 are stored in the background. Sampling African dust over the Atlantic Ocean is one of the standard capabilities of the NOAA research aircraft. Anecdotal evidence from onboard scientists indicates that the dust in 2007 lasted longer but was not as dense as the dust in previous hurricane seasons. The USGS office in St. Petersburg has a longstanding research interest in African dust. [larger version]

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.

Above left: View of a dropsonde, the main atmospheric-profile sampling device for the hurricane-research flights. The red tag at the bottom is a covering for the temperature sensor; the red tag in the middle is a port to add external power for calibration before the drop. Each dropsonde costs about $750; about 30 of them are typically used in a mission. [larger version]

Above right: The NOAA DeHaviland Twin Otter aircraft that was used in the early USGS extreme-storm lidar and photographic missions. Still photographs for the USGS photographic missions were taken through a bubble window toward the front, which was designed for marine-mammal surveys. [larger version]

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.

Above left: Janice Subino, who is digitizing the early USGS oblique aerial 35-mm slide photography, observes the inside of the Twin Otter aircraft. For marine-mammal surveys, NOAA commonly configures the Twin Otter with a spare fuel tank to extend its range. The tank, mounted inside the aircraft, is visible to the left. [larger version]

Above right: Tour participants from the USGS office in St. Petersburg included (left to right) Charlene Sullivan, Kara Doran, Kristy Guy, Janice Subino, and Dennis Krohn. [larger version]