THE CYGNSS NANOSATELLITE CONSTELLATION HURRICANE MISSION

Scott Gleason, Christopher S. Ruf, The CYGNSS Science and Engineering Teams

The Cyclone Global Navigation Satellite System (CYGNSS) is a spaceborne mission concept focused on tropical cyclone (TC) inner core process studies. CYGNSS attempts to resolve the principle deficiencies with current TC intensity forecasts, which lies in inadequate observations and modeling of the inner core. CYGNSS consists of 8 GPS bistatic radar receivers deployed on separate nanosatellites. The primary science driver is rapid sampling of ocean surface winds in the inner core of tropical cyclones

Tropical cyclone track forecasts have improved in accuracy by ~50% since 1990, largely as a result of improved mesoscale and synoptic modeling and data assimilation. In that same period, there has been essentially no improvement in the accuracy of intensity forecasts. The inadequacy in observations results from two causes: 1) Much of the inner core ocean surface is obscured from conventional remote sensing instruments by intense precipitation in the eye wall and inner rain bands. 2) The rapidly evolving (genesis and intensification) stages of the TC life cycle are poorly sampled in time by conventional polar-orbiting, wide-swath surface wind imagers. CYGNSS is specifically designed to address these two limitations by combining the all-weather performance of GNSS bistatic ocean surface scatterometry with the sampling properties of a constellation of satellites.

The use of a dense constellation of nanosatellite results in spatial and temporal sampling properties which are markedly different from conventional imagers. Detailed simulation studies will be presented which examine the sampling achieved by the 8 CYGNSS satellites. Detailed historical records of actual TC storm tracks are overlaid onto a simulated time series of the surface wind sampling enabled by the constellation. The low-cost spacecraft and GNSS receiver design of the CYGNSS missions will be reviewed in this presentation. Additionally, a demonstration of the CYGNSS end to end simulator and preliminary results of the wind retrieval performance will be presented.