WIVERN (Earth Explorer 11)

WIVERN (Wind Velocity Radar Nephoscope) is a European Earth observation satellite developed under the European Space Agency’s Earth Explorer programme. The spacecraft is designed to observe global winds, clouds, and precipitation and is led by ESA with European industrial partners.

WIVERN addresses a major observational gap in the global meteorological system: the lack of direct, globally distributed wind measurements within clouds. The mission was selected as ESA’s 11th Earth Explorer following the User Consultation Meeting in Prague on 9 July 2025. Its primary objective is to provide the first space-based measurements of in-cloud wind profiles on a global scale, directly supporting numerical weather prediction and climate research.

A central focus of the mission is the study of storm structure and dynamics. By measuring wind fields inside clouds, WIVERN will quantify the strength, structure, and horizontal extent of internal storm circulations. Observations will cover the full range of storm systems, from small convective cells a few kilometres across to large-scale systems extending up to 800 km, including tropical cyclones, extratropical cyclones, mesoscale convective systems, and polar lows.

WIVERN also targets the coupling between water, heat, and atmospheric circulation. The mission will relate the three-dimensional mass and heat structure of storms to their internal circulations and their interaction with mesoscale and large-scale atmospheric flow. These measurements are intended to improve understanding of how storms redistribute energy and moisture in the atmosphere.

Another major objective concerns cloud and precipitation impacts on climate. WIVERN will investigate the relationship between tropical convective activity and the extent and depth of anvil clouds, supporting improved constraints on climate sensitivity. Over the oceans, the mission will quantify shallow precipitation in trade cumulus and stratocumulus regimes and assess its influence on cloud organisation and climate feedbacks. In polar regions, WIVERN will improve measurements of snowfall, contributing to better estimates of surface mass balance and reduced uncertainties in climate and weather models.

The mission is designed to improve both numerical weather prediction models and Earth system models by providing high-resolution global observations of in-cloud winds and cloud properties. In addition, the dataset is expected to support the development and training of AI-based weather forecasting systems.

Secondary science objectives include improved observation of sea ice and snow in polar regions, with enhanced resolution of sea ice concentration and lead statistics, as well as characterisation of snow properties on sea ice. WIVERN will also contribute to oceanography by observing non-geostrophic ocean surface currents that are poorly captured by satellite altimetry, such as Ekman drift and near-inertial oscillations. Combined wind and surface current measurements will support studies of air–sea interaction processes.

WIVERN is developed under ESA leadership as part of the Earth Explorer programme, which focuses on innovative observation techniques to address specific Earth science questions. The mission’s core technology is a spaceborne Doppler cloud radar operating at millimetre wavelengths, enabling simultaneous measurements of wind and cloud microphysical properties. The payload design builds on European expertise in active remote sensing and cloud radar instrumentation.

The satellite carries a dual-polarisation Doppler radar operating at 94 GHz. The instrument uses a conical scanning geometry to measure line-of-sight wind velocities and radar reflectivity profiles within clouds and precipitation. Vertical resolution is approximately 640 m.

WIVERN provides an observation swath about 800 km wide, enabling near-global coverage with an average revisit time of around 1.5 days at the equator and about 1 day at latitudes above 50 degrees. Based on cloud reflectivity statistics, the mission is expected to observe between one and two million wind measurements per day meeting the World Meteorological Organization target accuracy of 2 m/s.

In addition to wind profiles, the radar will deliver high-resolution reflectivity data for rain, snow, and ice water, supporting improved estimates of the global hydrological cycle and atmospheric energy budgets with reduced sampling errors compared to previous cloud radar missions.

WIVERN was formally selected as ESA’s Earth Explorer 11 mission following the User Consultation Meeting held in Prague in July 2025. As an Earth Explorer mission, it proceeds through ESA’s defined development phases, including detailed design, industrial procurement, and spacecraft integration.

Launch details, including vehicle and exact schedule, are to be defined as the mission progresses through its development phases.