NASA's Genesis and Rapid Intensification Processes (GRIP) Field Experiment

In August–September 2010, NASA, NOAA, and the National Science Foundation (NSF) conducted separate but closely coordinated hurricane field campaigns, bringing to bear a combined seven aircraft with both new and mature observing technologies. NASA's Genesis and Rapid Intensification Processes (GRIP) experiment, the subject of this article, along with NOAA's Intensity Forecasting Experiment (IFEX) and NSF's Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) experiment, obtained unprecedented observations of the formation and intensification of tropical cyclones. The major goal of GRIP was to better understand the physical processes that control hurricane formation and intensity change, specifically the relative roles of environmental and inner-core processes. A key focus of GRIP was the application of new technologies to address this important scientific goal, including the first ever use of the unmanned Global Hawk aircraft for hurricane science operations. NASA and NOAA conducted coordinated flights to thoroughly sample the rapid intensification (RI) of Hurricanes Earl and Karl. The tri-agency aircraft teamed up to perform coordinated flights for the genesis of Hurricane Karl and Tropical Storm Matthew and the nonredevelopment of the remnants of Tropical Storm Gaston. The combined GRIP– IFEX–PREDICT datasets, along with remote sensing data from a variety of satellite platforms [Geostationary Operational Environmental Satellite (GOES), Tropical Rainfall Measuring Mission (TRMM), Aqua, Terra, CloudSat, and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)], will contribute to advancing understanding of hurricane formation and intensification. This article summarizes the GRIP experiment, the missions flown, and some preliminary findings.

As one of three concurrent hurricane field campaigns in 2010, GRIP gathered unprecedented observations—in particular with unmanned Global Hawk flights—to explore the relative importance of environmental and inner-core processes.

In August–September 2010, the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the National Science Foundation (NSF) conducted separate but closely coordinated hurricane field campaigns, bringing to bear a combined seven aircraft with both new and mature observing technologies. NASA's Genesis and Rapid Intensification Processes (GRIP) experiment, NOAA's Intensity Forecasting Experiment (IFEX; Rogers et al. 2006, 2013), and NSF's Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) experiment (Montgomery et al. 2012) obtained an unprecedented set of observations of the formation and intensification of tropical cyclones (TCs), including the storm environment and inner-core regions. NASA, NOAA, and NSF aircraft teamed up to perform coordinated flights for the genesis of Hurricane Karl and Tropical Storm (TS) Matthew and the nonredevelopment of the remnants of Tropical Storm Gaston. NASA and NOAA conducted coordinated flights to thoroughly describe the rapid intensification1 (RI) of Hurricanes Earl and Karl.

The major goal of GRIP was to better understand the physical processes that control hurricane formation and intensity change, specifically the relative roles of environmental and inner-core processes. GRIP focused on the following important science questions:

• Do environmental stability and moisture distributions (e.g., the Saharan air layer) play key roles in determining whether disturbances develop or fail to develop into TCs, or is the key factor related to dynamic processes and interaction with environmental vertical wind shear?
• Does the formation of cyclonic vorticity at the surface originate from midlevel cyclonic vorticity that builds downward, or does it originate at low levels and grow upward? What is the role of deep convection in this process?
• If the thermal structure of a vortical disturbance evolves from cold to warm core, then what physical processes are important for generating and maintaining the warm anomaly?
• What environmental (e.g., vertical wind shear, upper-level outflow jets, low- to mid-level moisture, upper-level troughs), oceanic (e.g. warm ocean eddies), and inner-core (e.g., convective bursts, mesovortices) factors govern RI?
• What is the predictability of RI, and what observations are most critical to its prediction?
• Do hot towers and convective bursts play a major role in RI or are they merely indicators of energy conversion processes (e.g., associated with movement over a warm ocean eddy)?

A major focus of GRIP was the application of new technologies to address these important scientific questions, including the first ever use of the unmanned Global Hawk (GH) aircraft for hurricane science operations. Using three different aircraft, NASA brought to the field an array of new instruments as well as older, well-tested technologies. The combined GRIP–IFEX–PREDICT datasets, along with remote sensing data from a variety of satellite platforms [Geostationary Operational Environmental Satellite (GOES), Tropical Rainfall Measuring Mission (TRMM), Aqua, Terra, CloudSat, and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)], will contribute to advancing understanding of hurricane formation and intensification. This article describes the NASA contribution to the tri-agency effort to understand better the processes that govern tropical storm formation and intensification. A particular focus is on the value of the new technologies that were brought to the field during GRIP, including the GH platform and some of the new instruments that provided valuable observations during the rapid intensification of Hurricane Karl. Observations from the NASA DC-8 are highlighted in the context of the interaction of Hurricane Earl with the Saharan air layer (SAL). All data from GRIP can be found online (at http://airbornescience.nsstc.nasa.gov/grip/getdata.html).

ADVANCED TECHNOLOGIES UTILIZED BY GRIP.

The GRIP campaign extended from 15 August to 25 September and involved three research aircraft (Table 1). The NASA DC-8 has been used in previous NASA hurricane field campaigns including the third Convection and Moisture Experiment (CAMEX-3), the fourth CAMEX (CAMEX-4; Kakar et al. 2006), and the NASA African Monsoon Multidisciplinary Analyses (NAMMA; Zipser et al. 2009).2 During GRIP, it was based in Fort Lauderdale, Florida, but it made three deployments to St. Croix in order to reach Hurricane Earl during its RI phase, ex-Gaston during a time of potential redevelopment, and Tropical Storm Matthew in its genesis stage. The DC-8 carried a diverse payload (Table 2), including environmental sensors for aerosols, water vapor, and winds, as well as remote and in situ sensors for inner-core precipitation structure and cloud microphysics. The NASA WB-57 was based out of Houston, Texas, but it occasionally deployed to Tampa Bay, Florida. Its payload consisted of the Hurricane Imaging Radiometer (HIRAD). The third aircraft was the GH aircraft, which was based at NASA's Dryden Flight Research Center (DFRC) in Southern California and carried the High-Altitude Monolithic Microwave Integrated Circuit (MMIC) Sounding Radiometer (HAMSR), High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), and Lightning Instrument Package (LIP). During the course of GRIP, the GH completed 5 flights, the DC-8 14 flights, and the WB-57 4 flights

Mission Overview

• This 3-D image of Celia was created from Tropical Rainfall Measuring Mission data on June 20 at 12 a.m. EDT that showed powerful thunderstorms in the southwest quadrant of the storm pushed to heights of almost 9.32 miles shown in red, with moderate to heavy rainfall. Credit: NASA
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