Speaker
Description
Combining space-borne limb and nadir measurements in the UV-visible spectral range (limb-nadir matching, LNM) provides valuable information on tropospheric ozone. This study uses data from the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) (2002-2012) and Ozone Mapping and Profiler Suite on board of Suomi National Polar-Orbiting Partnership (OMPS/NPP, since 2012). Both instruments observe the atmosphere in both limb and nadir geometry. Tropospheric ozone columns are retrieved globally by subtracting the stratospheric ozone column calculated from limb observations from the total ozone column derived from the nadir measurements.
Tropospheric ozone retrievals calculate the tropospheric ozone column using different upper altitude limits. In the case of the LNM technique, the upper limit is defined by the thermal and/or dynamical tropopause. Phase II of the Tropospheric Ozone Assessment Report (TOAR-II) uses different pressure levels for different latitudes as an upper limit for the tropospheric column.
After updating and improving the SCIAMACHY-LNM and the OMPS/NPP-LNM datasets, we are working to obtain a long-term dataset of tropospheric ozone (2002-2023) by merging them. Here, we present the challenges we face in harmonising and converting the dataset for different definitions of column heights as prescribed in TOAR II.
