500hPa zonal wind RMS error (2% adaptive obs)
3D-Var
LETKF
ØWith fewer
(2%) adaptive observations, ensemble spread sampling strategy
outperforms the other methods in LETKF
ØFor 3D-Var,
2% adaptive observations are not enough to make significant
improvement with any method
Rawinsonde; climatology; uniform; random; ensemble
spread; ÒidealÓ; 100%