Near-Real Time NOx emissions derived from observations of Sentinel missions

In the ESA project of DECSO-NRT-Europe, an operational system has been set up to derive daily NOx emissions in near-real time (NRT) for Europe based on observations of Sentinel 5P based on the offline inversion algorithm DECSO v6.5. This system has been developed to an NRT version for emissions on a spatial resolution of 0.1 x 0.1 degree (about 10x10 km). 

 The inversion algorithm DECSO has been developed at KNMI for the purpose of deriving emissions for short-lived gases. It is using a Kalman Filter implementation for assimilating satellite column observations, optimising the emissions. DECSO is built on top of the regional chemistry-transport model (CTM) CHIMERE, which converts the analysed emissions into 3D concentration fields. The emission forecast model is based on persistency, predicting that the emissions remain constant since the previous analysis. This has the important advantage that the derived NOx emissions do not depend on a-priori (bottom-up) information on the expected locations and source strengths. Only a single CTM forward run is needed which makes the system computationally efficient.  

In the operational system of DECSO-NRT, each day the European NOX emissions are automatically derived and visualized, while on the third of each month the monthly emissions are calculated for the previous month and available on the data portal of DECSO-NRT. An archive of NOx emissions is available from the year 2019 till last month, consisting of NOx emissions for the anthropogenic, agricultural soil and forest soil emission sectors. 

When Sentinel 4 observations of NO2 become available, the service will be extended with hourly NRT NOx emissions during daytime.