Wivern: a New Satellite Concept to Provide Global in-Cloud Winds, Precipitation and Cloud Properties

This work describes a conically scanning space-borne Dopp-lerised 940Hz radar Earth Science mission concept, WIVERN, Wind VElocity Radar Nephoscope. WIVERN will provide global measurements of in-cloud winds using the Doppler shifted radar returns from hydrometeors. The conically scanning radar is expected to provide wind data with daily revisits poleward of 50° at 50 km horizontal resolution and approximately 1km vertical resolution. The measured winds, when assimilated into weather forecasts and provided they are representative of the larger scale mean flow, should lead to further improvements in the accuracy and effectiveness of forecasts of severe weather and better focusing of activities to limit damage and loss of life. Surface clutter should impede wind measurement below 1 km above the ocean surface and below 2 km over land. The potential impact of the WIVERN winds on reducing forecast errors is estimated by comparison with the known positive impact of winds as measured by cloud motion and aircrafts. The main thrust of WIVERN is observing in-cloud winds, but WIVERN will also provide global estimates of ice water content, cloud cover and vertical distribution of cloud and ice water contents, thus continuing the data series started by CloudSat. The conical scan will provide increased coverage. As with CloudSat, estimates of rainfall and snowfall rates should also be possible. These additional products may also have a positive impact when assimilated into weather forecasts.