Flanched-Cross: An Efficient Cell Geometry for Beam Steering Metasurfaces with Orthogonal Polarisation Handling Capability

Geometry plays an important part in the characteristics of meta-cells used to design beam steering metasurfaces. One of the most desirable aspects of these cells is a large phase shift range that can be achieved with good transmission amplitude. However, the existing and most commonly used geometries for these cells are not able to produce a complete 360° phase range with an acceptable level of transmission amplitude. In this article, we present a new cell geometry, Flanched-Cross, that has superior transmission properties due to its unique shape and parametric variability than the commonly used geometries. The results are verified in simulation and further confirmed through prototyping and measurement. One- and two-dimensional steering are also performed for a dual-polarised base array to confirm the applicability of Flanched-Cross cell for beam steering purposes.

Flanched-Cross: An Efficient Cell Geometry for Beam Steering Metasurfaces with Orthogonal Polarisation Handling Capability

Geometry plays an important part in the characteristics of meta-cells used to design beam steering metasurfaces. One of the most desirable aspects of these cells is a large phase shift range that can be achieved with good transmission amplitude. However, the existing and most commonly used geometries for these cells are not able to produce a complete 360° phase range with an acceptable level of transmission amplitude. In this article, we present a new cell geometry, Flanched-Cross, that has superior transmission properties due to its unique shape and parametric variability than the commonly used geometries. The results are verified in simulation and further confirmed through prototyping and measurement. One- and two-dimensional steering are also performed for a dual-polarised base array to confirm the applicability of Flanched-Cross cell for beam steering purposes.

Validating TROPOMI aerosol layer height retrievals with CALIOP data

The Tropospheric Monitoring Instrument's (TROPOMI) level-2 aerosol layer height (ALH) product has now been released to the general public. This product is retrieved using TROPOMI's measurements of the oxygen A-band, radiative transfer model (RTM) calculations augmented by neural networks and an iterative optimal estimation technique. The TROPOMI ALH product will deliver aerosol layer height estimates over cloud-free scenes over the ocean and land that contain aerosols above a certain threshold of the measured UV absorbing index (UVAI) in the ultraviolet region. This paper provides background for the ALH product and explores its quality by comparing ALH estimates to similar quantities derived from spaceborne lidars observing the same scene. The spaceborne lidar chosen for this study is the Cloud-Aerosol Lidar with Orthogonal Polarisation (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, which flies in formation with NASA's A-train constellation since 2006 and is a proven source of data for studying aerosol layer heights. The influence of the surface and clouds are discussed and the aspects of the TROPOMI ALH algorithm that will require future development efforts are highlighted.