The capability of Sentinel-5p for aerosol monitoring is currently not used to its full potential. However, satellite observations in the spectral range of approximately 340 – 400 nm are known to have unique sensitivity to elevation and absorption of tropospheric aerosols. Traditionally, this sensitivity is used in many ozone monitoring instruments such as TOMS, GOME-1, SCIAMACHY, OMI and GOME-2 for deriving a UV Aerosol Index (UVAI) that provides valuable qualitative information on aerosol distribution. However, the UVAI does not have an explicit geophysical quantitative meaning and, therefore, it is not fully appropriate for utilization in the validation of aerosol transport models and other climate applications.
The reflectivity of the Earth’s surface is an important input parameter for many satellite retrievals of atmospheric composition. Some examples are e.g the retrieval of trace gases such as O3, NO2, BrO, CH2O, H2O, CO2, CO, and CH4, and of cloud information and aerosol optical depth (AOD). Recent developments in atmospheric remote sensing have focused strongly on deriving and implementing angular-dependent surface BRDF information (as opposed to using traditional, non-directional Lambertian surface reflectivity information), and on obtaining this information on a much higher spatial resolution than before.
The S5P+I AOD/BRDF project is focused on the aerosol and surface reflectance characterisation using capabilities of Sentinel-5p (TROPOMI) measurements. As such one objective of the project is to achieve quantitative characterization of aerosol properties from Sentinel-5p. Specifically, the aim is to develop the algorithm capable to provide Aerosol Optical Depth (AOD), i.e. aerosol load in the atmosphere as well as to provide information on absorption and the type of the aerosol. Next to this, another objective is the development of a spectral surface BRDF product.