CONICET | Buscador de Institutos y Recursos Humanos

We evaluated the impact of assimilating satellite observations over Argentina using the WRF-GSI-LETKF. While this is the first attempt to use the GSI system in Argentina as well as to assimilate satellite radiances in a regional context, previous work has shown promising results on mesoscale and convective scale data assimilation in the region (Dillon 2019, García Skabar and Nicolini, 2014). We conducted a case study corresponding to a huge mesoscale convective system (MCS) developed over central and north-eastern Argentina during November, 22th, 2018. This MCS developed during an Intense Observing Period (IOP) of the RELAMPAGO field campaign during Nov. 2018.Assimilation experiments were conducted using conventional observations and satellite-derived winds along with radiances from different infrared and microwave sensors (i.e. AMSU, HIRS, MHS, ATMS, AIRS and IASI). An online bias-correction approach is applied to reduce systematic errors during the assimilation processes. Analyses with 10-km horizontal grid spacing were produced with the GSI-4DLETKF system assimilating observations every hour from 11/20 18Z to 11/23 12Z. We used a 60-members multiphysics ensemble initialized from the GFS deterministic analysis with random perturbations. The impact of satellite radiances upon different aspects of the regional-scale circulation for this particular event is analyzed in this work. Comparing the vertical profiles of the different experiments shows that the radiance observations produce drying and increased temperature and northerly wind at the surface. This generates a convective environment with a maximum cape higher than 4000 Kg/J before the convection develops. The MSC generated as a result produced less precipitation than observed but it was well distributed over the domain.