Instrument Design and Performance of the HighFrequency Airborne Microwave and MillimeterWave Radiometer The highfrequency airborne microwave and millimeterwave radiometer (HAMMR) is a crosstrack scanning airborne radiometer instrument with 25 channels from 18.7 to 183.3 GHz. HAMMR includes: lowfrequency microwave channels at 18.7, 23.8, and 34.0 GHz at two linearorthogonal polarizations; highfrequency millimeterwave channels at 90, 130 and 168 GHz; and millimeterwave sounding channels consisting of eight channels near the 118.75xc2xa0GHz oxygen absorption line for temperature profiling and eight additional channels near the 183.31 GHz water vapor absorption line for water vapor profiling. HAMMR was deployed on a twin otter aircraft for a west coast flight campaign (WCFC) from November 4xe2x80x9317, 2014. During the WCFC, HAMMR collected radiometric observations for more than 53.5 h under diverse atmospheric conditions, including clear sky, scattered and dense clouds, as well as over a variety of surface types, including coastal ocean areas, inland water and land. These measurements provide a comprehensive dataset to validate the instrument.

Measuring the Directional Ocean Spectrum from Simulated Bistatic HF Radar Data HF radars are becoming important components of coastal operational monitoring systems particularly for currents and mostly using monostatic radar systems where the transmit and receive antennas are colocated. A bistatic configuration, where the transmit antenna is separated from the receive antennas, offers some advantages and has been used for current measurement. Currents are measured using the Doppler shift from ocean waves which are Braggmatched to the radio signal. Obtaining a wave measurement is more complicated. In this paper, the theoretical basis for bistatic wave measurement with a phasedarray HF radar is reviewed and clarified. Simulations of monostatic and bistatic radar data have been made using wave models and wave spectral data. The Seaview monostatic inversion method for waves, currents and winds has been modified to allow for a bistatic configuration and has been applied to the simulated data for two receive sites. Comparisons of current and wave parameters and of wave spectra are presented. The results are encouraging, although the monostatic results are more accurate. Large bistatic angles seem to reduce the accuracy of the derived oceanographic measurements, although directional spectra match well over most of the frequency range.