Forecast Sensitivity Observation Impact (FSOI) Inter-comparison Experiment

Forecast Sensitivity Observation Impact (FSOI) techniques provide a practical means to estimate the forecast impact of all assimilated observations for NWP systems.  In this presentation, we describe direct comparisons of FSOI quantities between different NWP systems.  A common “baseline” set of FSOI experimental parameters are applied for the time period December-February (DJF) 2014/2015.  An adjoint-based FSOI approach (1) is applied for the NWP systems at NASA/GMAO, the Naval Research Laboratory (NRL) and the UK Met Office; whereas an ensemble-based FSOI approach (2) is applied at the National Centers for Environmental Prediction (NCEP).  The Japan Meteorological Agency (JMA) applies both the adjoint-based and ensemble-based FSOI capabilities, enabling a direct comparison of the two techniques.  Given the aforementioned experiment, we plan to describe the differences in aggregated FSOI quantities between NWP systems for the relevant observing systems.  Additionally, NWP system inter-comparisons of FSOI quantities for common observation subsets within the 3-month period will be presented.  The comparisons of observation subsets will provide insight as to the extent to which the aggregate results are representative in both space and time.

(1) Langland, R. H. and Baker, N. L. 2004.  Estimation of observation impact using the NRL atmospheric variational data assimilation adjoint system. Tellus A. 56, 189-201

(2) Kalnay, E., Ota, Y., Miyoshi, T. and Liu, J. 2012.  A simpler formulation of forecast sensitivity to observations:  application to ensemble Kalman filters. Tellus A. 64. 18462