Gulfstream IV-SP (G-IV)

The Gulfstream IV-SP (G-IV) is a high altitude, high speed, twin turbofan jet aircraft acquired by AOC in 1996. The G-IV is currently configured for operational support of the National Hurricane Center synoptic surveillance mission and is expected to provide support for NOAA programs for many years to come. This mission is designed to collect, process and transmit vertical atmospheric soundings in the environment of the hurricane. The principle tool used for this task is the GPS dropwindsonde.

The dropsonde is released from the G-IV measuring and transmitting back to the aircraft the pressure, temperature, humidity, and GPS Doppler frequency shifts as it descends to earth. The Doppler shifts are used to compute the horizontal and vertical wind components. After analysis and processing of the dropsonde data the information is formatted into a TEMP-DROP message using the standard WMO format. The TEMP-DROP message is then transmitted to the National Centers for Environmental Prediction and the National Hurricane Center for inclusion into the global and hurricane model runs. The TEMP-DROP message is also provided to the hurricane forecaster providing real-time observations depicting the synoptic patterns surrounding the hurricane.

Gulfstream G-IV SP (Special Performance)

Gulfstream G-IV SP Transformation Article

STANDARD AIRCRAFT SPECIFICATIONS

The specific equipment and systems onboard the G-IV for the hurricane surveillance mission are the:

• Main Aircraft Data System

- Two Data System Modules for instrument interface and data collection
- Four Networked Sun Sparc5 Workstations
- Extensive atmospheric instrumentation

• Airborne Vertical Atmospheric Profiling System

- Dropsonde Data System for drop execution, data collection and storage
- Dropsonde Launch Chute
- GPS dropwindsonde

• Hurricane Analysis and Processing System

- Workstation accomplishes data analysis, processing, and message formatting

• Internal/External communication system

- VHF, UHF, ADF, Flight Phone, SATCOM and Passenger Communication System

• Rockwell Collins WXR-700C C-Band Weather Radar w/ 30-inch antenna

The G-IV aircraft is on standby or deployed 180 days for hurricane surveillance, another 30-60 days are required for instrumentation and calibration, and 30 days for maintenance and training while anticipating between 200 to 300 hours of flying every year.

NOAA G-IV Winter Storms Reconnaissance

In order to more accurately predict the location and intensity of high winds, destructive surf conditions, severe weather and flooding rainfall caused by winter storms, the NOAA National Centers for Environmental Prediction (NCEP) instituted the Winter Storms Reconnaissance (WSR) program in 1998. Each year since then, the NOAA G-IV has served WSR from bases in Anchorage, AK and Honolulu, HI. In 2003, the G-IV will base from Hawaii, conducting approximately 20 missions over the North Pacific, into the breeding grounds of these future US-bound storms.

Over the years, NOAA NCEP has developed a method called targeted observations, whereby the NOAA jet is directed in advance to regions of the atmosphere where storm prediction models indicate enhanced data will have the most positive influence on the forecast accuracy. Once over these locations, dropwindsondes are launched to provide vertical soundings of the atmosphere between the aircraft and the ocean’s surface. Targeted observations have proven themselves in more than 90% of storm cases, generally improving the accuracy of storm track and intensity prediction between 10% - 20%. Another way to judge the public impact is that quantitatively, these additional observations from the G-IV result in giving emergency managers an extra day’s notification in which to declare warnings of severe weather events ahead.

During the WSR-03 project, the NOAA G-IV will simultaneously make a number of air chemistry measurements in the upper troposphere and lower stratosphere in the active jet stream area above the Pacific winter storms. Measurements will include ozone, carbon monoxide, and volatile organic compounds, also known as hydrocarbons. Also, in the late February and early March 2003 period, the G-IV will fly coordinated missions with NASA aircraft to thoroughly profile the atmosphere directly from aircraft sensors and with dropwindsondes. NASA uses this information for validation of satellite instruments and for future satellite design.

For more information on the Winter Storms project visit http://www.emc.ncep.noaa.gov/