During the 2002, 2003, and 2004 Hurricane seasons, and the 2005 Ocean Winds and Rain Winter Experiment, the University of Massachusetts (UMass) installed two instruments on the NOAA N42RF WP-3D research aircraft: the Imaging Wind and Rain Airborne Profiler (IWRAP) and the Simultaneous Frequency Microwave Radiometer (SFMR). IWRAP is a dual-band (C- and Ku), dual-polarized pencil-beam airborne radar that profiles the volume backscatter and Doppler velocity from rain and that also measures the ocean backscatter response. It simultaneously profiles along four separate incidence angles while conically scanning at 60 RPM. SFMR is a C-band nadir viewing radiometer that measures the emission from the ocean surface and intervening atmosphere simultaneously at six frequencies. It is designed to obtain the surface wind speed and the column average rain rate. Both instruments have previously been flown during hurricane seasons 2002, 2003 and 2004.Spectral techniques can been used to differentiate the contributions of the volume backscatter from rain from the ocean surface backscatter. Initial results from the Winter 2005 datasets are presented. Attenuation from rain is also particularly important at high microwave frequencies such as Ku-band. Thanks to IWRAP's profiling capabilities, Ku-band attenuation models and dropsize distribution (DSD) parameters of the observed precipitation from dual-wavelength techniques within tropical cyclones are presented.

During the 2002 and 2003 ONR CBLAST Hurricane Program Field (HPF) and the NOAA/NESDIS Hurricane Ocean Winds and Rain Experiment, the University of Massachusetts (UMass) installed IWRAP, a conically scanning dual-band (C- and Ku-band), dual-polarized pencil-beam airborne Doppler radar that profiles the volume backscatter and Doppler velocity from rain and the backscatter from the ocean surface simultaneously at four incidence angles covering incidence angles from 25 to 55 degrees. From the measurements acquired during missions flown through hurricanes Gustav, Isadore, and Lili (2002) and Fabian and Isabel (2003), high wind regime Geophysical Model Functions have been derived at both frequencies and polarizations. Concrete saturation effects in the NRCS are presented, and sensitivity in the wind direction at high wind speed is discussed through the analysis of the second harmonic of the NRCS.

IWRAP, the imaging wind and rain airborne profiler, is the first high-resolution dual-hand airborne Doppler radar designed for studying the inner core of tropical cyclones (TCs). The system is designed to provide high-resolution, dual-polarized C and Ku-Band reflectivity and Doppler profiles of precipitation volume backscatter and ocean surface backscatter within the inner core precipitation bands of tropical cyclones (TCs). SFMR is a C-band nadir viewing radiometer used operationally to provide continuous estimates of the surface wind speed and title column average rain rate. Both IWRAP and SFMR arc operated from a National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft during missions through TCs and severe ocean storms. In this paper, we present wind and reflectivity profiles of the atmospheric boundary layer within the inner-core of hurricane Isabel (2003) from IWRAP measurements. These profiles are the highest resolution measurements of the ABL winds of a hurricane ever obtained. The profiles are compared to coincident surface wind speed measurements provided by SFMR, flight level wind measurements and GPS dropsonde winds

The University of Massachusetts (UMass), with support from ONR, NOAA and NASA, has developed a novel radar system called the Imaging Wind and Rain Airborne Profiler (IWRAP). IWRAP is a dual frequency (C/Ku band) dual polarized airborne radar that profiles the volume and surface backscatter and Doppler simultaneously at 30, 35, 40 and 50 degrees incidence, while conically scanning at 30 to 90 rpm. Its range resolution can be set at 15, 30, 60 or 120 m. From these measurements the ocean surface wind field, 3-D boundary layer winds within rain bands can be mapped. IWRAP was flown during the 2002 NOAA/NESDIS/ORA Hurricane Ocean Winds Experiment, which was conducted in conjunction with the 2002 NOAA/AOML/HRD Hurricane Field Program. This paper presents the system design, radar processing algorithms and initial results from the 2002 hurricane flights.

Airborne ocean backscatter dual polarization measurements at C and Ku-band obtained in high wind speed conditions (20 to 60 m/s) are presented. The VV and HH NRCS measurements are compared. The preliminary comparisons show that the HH NRCS measurements are slightly more sensitive to the surface wind speeds for high wind speed and precipitation conditions.