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Intensity Forecasting EXperiment 2005
(IFEX05)

IFEX calendar
more details on IFEX
IFEX/NASA brief

NOAA's Hurricane Research Division, part of the Atlantic Oceanographic and Meteorological Laboratories located in Miami, FL, will begin a multi-year experiment this summer with the NOAA Aircraft Operations Center (AOC) called the Intensity Forecasting Experiment (IFEX). Developed in partnership with NOAA's Environmental Modeling Center (EMC) and its Tropical Prediction Center, IFEX is intended to improve our understanding and prediction of hurricane intensity change by collecting observations that will aid in the improvement of current operational models and the development of the next-generation operational hurricane model, the Hurricane Weather Research and Forecasting model (HWRF). Observations will be collected in a variety of hurricanes at different stages in their lifecycle, from formation and early organization to peak intensity and subsequent landfall or decay over open water.

There are several unique aspects of IFEX in 2005 that will help improve our understanding and prediction of hurricane intensity change:

  • Hurricane genesis experiment - This experiment, flown with the two NOAA P-3 aircraft in conjunction with a high-altitude ER2 NASA aircraft, is intended to improve our understanding of how a tropical disturbance becomes a hurricane. Very few aircraft measurements have been made in tropical disturbances over the past 25 years, largely because it is so difficult to collect data in these systems. The eastern Pacific Ocean is an ideal location for genesis studies, since that region has the highest frequency of developing hurricanes per unit area in the world. Because most eastern Pacific storms originate close to Central America and Mexico, NOAA and NASA aircraft will base operations out of San Jose, Costa Rica in an attempt to observe developing hurricanes. These measurements will cover an important portion of a hurricane's lifecycle that will aid in the understanding and prediction of hurricane formation. This experiment will run from July 3 to July 23.

  • SFMR validation - The Stepped-Frequency Microwave Radiometer (SFMR) is a unique airborne tool that enables the remote measurement of surface wind speeds and rain rates over the water. The SFMR has provided TPC with a valuable means of determining the maximum surface wind speed as well as the extent of hurricane (>73 mph) and gale-force (39-54 mph) winds. This information enables more accurate timing and location of hurricane and tropical storm watches and warnings. Work will continue during IFEX to validate the operational SFMR by comparing it with direct measurements from GPS dropsondes, packaged sensors deployed from aircraft, in these environments.

  • Impact of Saharan air on intensity forecast models - Recent research has shown that very dry air originating from the African continent, called the Saharan Air Layer (SAL), may be an important factor in hurricane intensity change in the North Atlantic and Caribbean Sea. The SAL feature may play an important role in the ability of operational models to predict hurricane intensity, since the presence of dry air can significantly impact the strength and longevity of the vigorous convection that drives hurricanes. These studies suggest that providing accurate measurements of humidity for incorporation into hurricane models could produce better tropical cyclone intensity forecasts and also suggests that further research is needed to understand how the SAL affects tropical cyclone intensity. High-quality moisture data provided by GPS dropsondes deployed by the NOAA G-IV jet will provide these observations to better prescribe the initial conditions in the operational global model.

  • Mapping of the center wind field from airborne tail Doppler radar and its transmission to EMC and TPC in real-time - Scientists onboard the NOAA P-3's will test a method for sending radar-derived wind measurements of a hurricane's inner-core to EMC in real-time. These measurements will ultimately be used in the development of techniques for incorporating data into models that can be applied to storms at all stages of their lifecycle. These measurements will also be sent to TPC, where they will be evaluated for the potential of being routinely provided to the hurricane specialists during the hurricane season.

  • Aerosonde project - While the capabilities and utilization of the WP-3D Orion and Gulfstream 4 aircraft have made NOAA a global leader in hurricane aircraft surveillance and reconnaissance, detailed observations of the near-surface hurricane environment (sea level to 500 meters) have been elusive due to the severe safety risks associated with low level manned flights. A successful deployment the unique low flying unmanned Aerosondes will accurately document and improve our understanding of the rarely-observed near surface hurricane environment. An important (and immediate) additional benefit would be the real-time transmission of hurricane surface conditions directly to the OAR. In addition, detailed comparisons between in-situ and satellite-derived observations will also be possible.

  • Real-time transmission of lower fuselage radar - For the first time ever, a NOAA P-3 will be transmitting lower fuselage radar imagery in real-time to another aircraft, the Naval Research Laboratory (NRL) P-3. The NRL P-3 will be flying outside of a hurricane's rainbands while the NOAA P-3 will be flying along the more turbulent inner edge of the rainbands. This capability will enable the safe operation of the NRL P-3 in an environment it has never flown in before.

  • High-altitude penetrations of the hurricane's center - During this year the high-altitude NOAA G-IV jet will penetrate the inner core of hurricanes. This capability will be vital once a Doppler radar is installed on the G-IV, enabling the three-dimensional mapping of wind fields from nearly top to bottom of hurricanes. These wind measurements will prove invaluable in improving the forecasts of hurricane intensity with the next-generation HWRF model.

  • Hurricane decay experiment - Developed jointly between TPC and HRD, this experiment will examine the decay of hurricanes in the eastern North Pacific. Direct observations are rarely, if ever, available in eastern North Pacific hurricanes decaying over cooler waters. The intensity of these systems is typically estimated remotely by the Dvorak technique, supplemented by satellite wind estimates from QUICKSCAT observations. However, there is some evidence that the Dvorak technique overestimates the intensity of weakening systems, thus overstating the hazard to marine interests. The purpose of this experiment is to obtain direct observations of decaying hurricanes to better calibrate existing methods of estimating hurricane intensity over cold water.

During this year, IFEX will be operating in partnership with several other experiments:

  • NASA Tropical Cloud Systems and Processes (TCSP) Experiment - TCSP, conducted by NASA and the National Oceanic and Atmospheric Administration (NOAA) in Costa Rica throughout July 2005, will be monitoring oceanic thunderstorms to study why some thunderstorms develop into tropical cyclones and some do not. Understanding how hurricanes and other tropical storms are formed and intensify could dramatically improve weather forecasting capabilities and better safeguard human lives and property. Working from Juan Santa Maria Airport in San Jose, Costa Rica, the hurricane team is conducting ground-based and airborne studies to measure the buildup and behavior of tropical storm systems before they evolve into life-threatening hurricanes. A number of missions will be flown over the region, using NASA's ER-2 and NOAA's WP-3D Orion aircraft and unmanned aerial vehicles called "Aerosondes." The airborne experiments will collect temperature, humidity, precipitation, and wind information related to tropical cyclones and other phenomena that often lead to development of more powerful storms at sea. For NASA Fact Sheet on TCSP click here.

  • NSF Hurricane Rainband and Intensity Change Experiment (RAINEX) - The main goal of RAINEX is to investigate interactions between a tropical cyclone's inner core and its associated rainbands, and the role this interaction plays in determining intensity change. Both NOAA P-3's will be flying with the NRL P-3, providing, for the first time ever, three Doppler-radar equipped aircraft simultaneously measuring the wind field in a hurricane. Such concurrent measurements of a mature hurricane will improve our understanding of hurricane intensity change and help improve methods for incorporating observations into the operational hurricane models run at EMC. The National Science Foundation is providing support for researchers from the Universities of Miami and Washington, as well as the NRL P-3.

  • NOAA Ocean Winds Experiment - The goal of the Ocean Winds experiment is to further our understanding of wind direction and speed retrievals at the ocean surface level from microwave remote-sensing measurements in high wind conditions and in the presence of rain. Measurements taken from the Ocean Winds experiment in mature storms will aid in the understanding and improvement of satellite remotely-sensed wind measurements which are currently used operationally by marine forecates and in numerical weather prediction models.

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