Assessment of atmospheric stability measurements from microwave radiometer observations for wind energy applications

Atmospheric stability is a measure of atmospheric status which determines whether thermodynamically perturbed air will rise, sink, or be neutral. Atmospheric stability has a major impact on the evolution of wind turbine wakes and thus on the yield and performance of offshore wind parks. For estimations of wind park power output and for improving analyses of offshore wind park wakes, a crucial parameter was found to be profiles of atmospheric temperature and stability metrics. Atmospheric temperature profiles can be measured in-situ by balloon-borne sensors, but also estimated from the ground using remote sensing observations.

Ground-based microwave radiometer (MWR) units operating in the 22-30 GHz and 50-60 GHz bands are commonly used to estimate atmospheric temperature and humidity profiles. A handful of MWR profiling types are nowadays available as off-the-shelf commercial products, and a MWR network is currently being established in the framework of EUMETNET E-PROFILE programme (Rüfenacht et al., 2021). This presentation reviews the stability metrics useful for monitoring wind park performances and provides a quantitative assessment of the value of MWR observations to estimate these stability metrics from near surface, either over land or ocean. Results from three different MWR instruments, representing the most common available on the market, will be presented, as obtained during at least three field experiments, both onshore and offshore.

This contribution presents the main outcomes of the Radiometry and Atmospheric Profiling (RAP) scoping study, carried in the framework of the COST Action PROBE (https://www.probe-cost.eu/) and funded by Carbon Trust and the partner companies of the Off-shore Wind Accelerator (OWA) program: (in alphabetical order) EnBW, Equinor, Orsted, RWE, Scottish Power Renewables, Shell, SSE Renewables, Total Energies, Vattenfall.