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The pulse compression scheme implemented on the Imaging Wind and Rain Air-borne Profiler (IWRAP) is described. Developed at the UMASS Microwave Remote Sensing Laboratory (MIRSL), IWRAP is a dual-band (C and Ku) conically scanning Doppler scatterometer designed to map the atmospheric boundary layer wind fields, ocean surface wind fields, and precipitation within tropical cyclones. IWRAP has previously been deployed using a pulsed transmit waveform with a peak transmit power of 80 watts. This limits the average transmit power and sensitivity for the system which affects the more distant range gates (especially at Ku-band). As a result, IWRAP could operate only at lower altitudes (approx. 5000 ft) causing safety concerns and limiting the missions for which it can be deployed. Increasing sensitivity was achieved by converting IWRAP to a pulse compression radar system. Pulse compression is a technique that combines the increased energy of a longer pulse with the high resolution of a short pulse by implementing a frequency modulated (FM) “chirped” transmit waveform. This method requires advanced signal processing, in which the received signal is passed through a filter to compress the pulse on the receiving end. A system with various chirp/filtering schemes as well as a new control system which UMASS has recently developed will be discussed in this thesis.

Reliable ocean wind vector measurements can be obtained using active microwave remote sensing (scatterometry) techniques. With the increase in the number of severe hurricanes making landfall in the United States, there is increased emphasis on operational monitoring of hurricane winds from aircraft. This thesis presents a data processing algorithm to provide real-time hurricane wind vector retrievals (wind speed and direction) from conically scanning airborne microwave scatterometer measurements of ocean surface backscatter. The algorithm is developed to best suit the specifications for the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division's airborne scatterometer – Integrated Wind and Rain Airborne Profiler (IWRAP). Based on previous scatterometer wind retrieval methodologies, the main focus of the work is to achieve rapid data processing to provide real-time measurements to the NOAA Hurricane Center. A detailed description is presented of special techniques used. Because IWRAP flight data were not available at the time of this development, the wind retrieval performance was evaluated using a Monte Carlo simulation, whereby radar backscatter measurements were simulated with instrument and geophysical noise and then used to infer the surface wind conditions in a simulated (numerical weather model) hurricane wind field

The Imaging Wind and RAin Profiler (IWRAP) is an airborne scatterometer system built and operated by University of Massachusetts Amherst's Microwave Remote Sensing Laboratory (MIRSL). The radar is seasonally deployed aboard one of the two National Oceanic and Atmospheric Administration (NOAA) WP-3D Orion ``Hurricane Hunter'' aircraft based out of MacDill AFB in Tampa, Florida. IWRAP is a dual-frequency, Ku- and C-band, scatterometer that uses two conically scanning antennas to estimate the ocean surface wind vectors as well as intervening rain profiles. Data that is gathered with IWRAP is used to improve current Geophysical Model Functions (GMF) or to help derive new GMFs for other undocumented incidence angles. This thesis outlines the improvements and changes made to the IWRAP system from 2009-2011. Chapter Two describes the IWRAP instrument including a description of the instrument status as of Fall 2009, and a summary of instrument operations in 2010 and 2011. Chapter Three describes hardware and software modifications to support dual-polarization. It also describes hardware-based and flight-based attempts to observe at large incidence angles. Chapter Four is an analysis of the stability of the internal calibration both during flights and over a season. System documentation is consolidated into a single technical manual in Appendix A.