The Gulfstream jet era
NOAA
began in earnest in 1994 obtaining a high-altitude jet for hurricane
and synoptic weather investigations. A Gulfstream IV (G-IV) jet
was purchased by NOAA and instrumented. It was ready to fly by late
1996 and first used in a hurricane synoptic flow mission in 1997.
New dropwindsondes were developed to replace the obsolete Omega
sondes. The new sondes employed the Global Position Satellites (GPS)
to obtain more accurate positions, and hence, more accurate winds.
These new sondes were also more liquid water tolerant and for the
first time soundings were made inside the hurricane eyewall, in Hurricane Guillermo
over the East Pacific. Insights were gained about the hurricane boundary-layer
wind structure from these and other drops.
At the start of the 1995 hurricane season Dr. Burpee became Director
of NHC, the fourth NHC Director to come from NHRP/NHRL/NHEML/HRD
(after Drs. Bob Simpson, Neil Frank, and Bob Sheets). Dr. Hugh Willoughby took
over as Director of HRD.
The Division has been experimenting with ensemble
predictions. Small perturbations are introduced into a computer
model's initial conditions and run several times with different
perturbations. The resulting suite of forecasts are then
synthesized into one forecast, one from which most chaotic noise
has been reduced. These ensemble forecasts help point to areas
over the open ocean from which data is most critical, and G-IV
dropsonde flights can be planned for these sections.
HRD scientist, with their experience with both the G-IV
jet and GPS sondes, participated in the NORth Pacific EXperiments
(NORPEX) in 1998 and 1999. Run at the same time as the CALJET
experiment using the P3 aircraft, these experiments measured
Pacific storms that could threaten the western U.S. coast
and examined how they might be affected by the 1997-98 El
Niño. NORPEX in 1999 has been renamed Winter Storm
Reconnaissance '99. And HRD participation continued
with Winter Storm Reconnaissance 2000, operating out of
Anchorage, studying Gulf of Alaska polar lows, and WSR 2001,
operated out of Honolulu, studying Kona lows and jet stream
turbulence.
Work continues on the development on the SFMR as well as a new
microwave scatterometer which can measure the wind direction of
surface winds from the P3 aircraft, even through rain and clouds.
This will provide NHC hurricane specialist with a more accurate
assessment of the hurricane's surface winds near the time of
landfall.HRD also runs the H*Wind project, which
brings together wind measurements from aircraft, satellites,
ships, and buoys and creates an integrated near surface wind
analysis field. These fields are given to NHC's hurricane
specialists in real-time, and are later posted on the World Wide
Web for researchers around the globe.
In 2003 Dr. Willoughby left HRD to join Florida
International University's International Hurricane Research
Center (IHRC). Dr. Frank Marks, for many years the leader
of the annual Hurricane Field Program, assumed the Directorship.
HRD will continue on into the 21st Century as NOAA's
focus for hurricane research, with extensive co-operation with
NHC, AOC, USAF, USN, other government agencies, the academic
community, and with the private sector. Improvements in computer
forecasts are expected to come with further work, as is improved
knowledge of hurricane climatology in a changing world.
References...
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