Andreas Rhodin, German Weather Service
Choice of localisation length scales in a hybrid EnVar/LETKF
Abstract:
At DWD a hybrid global data assimilation system (13 km deterministic
EnVar coupled to a 40 km LETKF) is operational since January 20th
2016. The initial configuration is based on fixed localisation length
scales (300 km horizontally, 0.3 to 0.8 scale heights vertically) in
both components.
This talk examines the range of correlation length scales present in
the background ensemble and explores options for a more sophisticated
consideration of the range of scales in the setup of the hybrid
system.