Abstract's details
Development of a new UAV-based LiDAR altimetry solution for in-situ wave spectrum estimation
CoAuthors
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: CFOSAT
Presentation type: Type Oral
Contribution: PDF file
Abstract:
For two years now, the development of a UAV-based (Unmanned Aerial Vehicle) LiDAR altimetry system (the vorteX.io VTX-1 light altimeter) has demonstrated its capability to perform water surface height measurements with centimeter accuracy on various inland water bodies (lakes, rivers and estuaries). This unique, new type of lightweight altimeter has been developed specifically for measuring water surfaces. It is based on a LiDAR with 8 beams emitted in the near infrared uniformly distributed over an aperture of 16° perpendicular to the along-track direction of the UAV. Thus, depending on the surface roughness, 8 surface height measurements are acquired simultaneously.
The main objective of the study is the development of a new calibration/validation solution for satellite altimetry systems based on the use of LiDAR onboard UAVs to measure wave/swell spectra over the ocean. In this framework we combine LiDAR acquisitions in the open sea and inversion processing on these measurements in order to extract the sea surface state parameters. We take advantage of the UAV's deployment capabilities and the combination of LiDAR and optical measurements from the vorteX.io light altimeter to develop a new, relevant and flexible calibration solution of radar altimeters but also with the goal of the calibration of the SWIM radar scatterometer measurements onboard CFOSAT.
In this framework, we first simulate LiDAR measurements of sea surface height based on the CNES simulator RADARSPY. Then, after defining a specific flight plan, we developed an algorithm performing the estimation of the directional wave spectrum through the sea surface height measurements acquired by the lightweight altimeter. Then a field campaign has been realized close to Saint-Jean-de-Luz (South of France) where drone flights were performed over sea above a wave buoy from the French network CANDHIS. After the data processing of the actual drone measurements, the estimated directional wave spectrum were computed and compared to the one estimated from the CANDHIS. We present in this study the results of the simulations, the developed directional wave spectrum estimator, the drone flight over ocean and the comparisons with the CANDHIS buoy and the final results.
The main objective of the study is the development of a new calibration/validation solution for satellite altimetry systems based on the use of LiDAR onboard UAVs to measure wave/swell spectra over the ocean. In this framework we combine LiDAR acquisitions in the open sea and inversion processing on these measurements in order to extract the sea surface state parameters. We take advantage of the UAV's deployment capabilities and the combination of LiDAR and optical measurements from the vorteX.io light altimeter to develop a new, relevant and flexible calibration solution of radar altimeters but also with the goal of the calibration of the SWIM radar scatterometer measurements onboard CFOSAT.
In this framework, we first simulate LiDAR measurements of sea surface height based on the CNES simulator RADARSPY. Then, after defining a specific flight plan, we developed an algorithm performing the estimation of the directional wave spectrum through the sea surface height measurements acquired by the lightweight altimeter. Then a field campaign has been realized close to Saint-Jean-de-Luz (South of France) where drone flights were performed over sea above a wave buoy from the French network CANDHIS. After the data processing of the actual drone measurements, the estimated directional wave spectrum were computed and compared to the one estimated from the CANDHIS. We present in this study the results of the simulations, the developed directional wave spectrum estimator, the drone flight over ocean and the comparisons with the CANDHIS buoy and the final results.