XOVWM: the Next-Generation Ocean Surface Vector Winds Mission

The Extended Ocean Vector Winds Mission (XOVWM) has been recommended by the National Research Council in its decadal review recommendation to NASA and NOAA as the next-generation mission dedicated to measuring Ocean Surface Vector Winds (OSVW). In this presentation, we give a description of the goals of the XOVWM instrument concept and concentrate on its application of the remote sensing of hurricanes from space.

Measuring OSVW from space is a severe challenge: on the one hand, one must implement an instrument that is able to measure winds for the entire range of winds speeds and in the presence of severe rain conditions. On the other hand, one must strive to retain the utmost spatial resolution in order to capture all of the physical phenomena present under tropical cyclone conditions.

In the past these conflicting requirements have not been met in a single instrument. Traditional Ku-band scatterometers, such as the ongoing NASA Ku-band QuikSCAT mission, have shown the ability of determining gale and storm level winds, but fall short of the requirement to be able to monitor wind up to hurricane levels and under all-weather conditions. The EUMETSAT C-band scatterometer is able to monitor a greater wind speed range, but sacrifices the spatial resolution required to properly resolve hurricane physical mechanisms. Similarly, passive measurements of hurricanes, such as the one implemented by the WindSat mission, fall short of the all-weather capability and the spatial resolution requirements.

The XOVWM concept tries to leverage the best from all existing technologies. It includes a Ku-band scatterometer using synthetic aperture radar processing to achieve wind retieval at 5km resolution, or better. The high wind speed limitations of Ku-band measurements are removed by adding a horizontally polarized C-band channel, which is able to retrieve winds at high wind speeds. Finally, an X-band polarimetric radar is included in the instrument suite to remove rain contamination.

In this paper we describe the XOVM instrument design and the trades that have been made to obtain an instrument which will address the needs for high-resolution, all-weather, wind retrievals for tropical cyclone conditions. We then describe the expected instrument performance under a variety of environmental conditions and different tropical and extra-tropical cyclones.