AIR QUALITY STUDIES IN MEXICO CITY USING THE NO2 OBSERVATIONS OF TEMPO
Since 7 April 2023 the space based observatory TEMPO has been in operation in a geostationary orbit above the Americas and provides continuous measurements. Mexico City is in its field of regard and TEMPO provides a great opportunity for air quality studies and also new challenges for satellite validation in this Megacity. The interaction of pollutants with human health takes place at the surface and the information about surface concentrations are of primary interest from a medical perspective.
Satellite based measurements do not provide surface concentrations, but information with columnar character. To retrieve information about the concentration near the surface we have to develop strategies, methods and algorithms.
For mitigation of pollutants, the perspective of stake holders, which decide on matters to reduce the pollution, the amount of pollutants, which is more described by the vertical column in the boundary layer is important and how it is developing in time, as surface concentrations have a very local character and are extremely sensitive to vertical and horizontal transport. But also for the reported vertical tropospheric column of TEMPO might differ from the integrated column amount, if the optical properties assumed in the radiative transfer model of the algorithm differs from the real properties in the Mexico City boundary layer.
Especially in the UV-Vis region the real characteristic and sensitivity of the measurements of pollution in different altitudes depends on the radiative transfer which includes the scattering in the atmosphere.
In this contribution we present a strategy to derive surface near concentration, compare results of the strategy to ground based measurements as the RAMA network operated by the local government in Mexico City and available remote sensing measurements from the ground truthing facility at the UNAM Campus.