Sampling strategies
¥Ensemble
spread strategy (from Local Ensemble Transform Kalman Filter)
® Adaptive observations are at locations with large ensemble
wind spread at 500hPa.
® 3D-Var and LETKF have the same adaptive observation
points
¥Random picking
® Randomly pick locations from potential locations.
¥Uniform distribution
® Uniformly distributed.
¥Climatology ensemble spread
® Adaptive
observations are at locations with large climatological average
ensemble wind spread from rawinsonde assimilation.
® Constant with time, and same for 3D-Var
and LETKF.
¥ÒIdealÓ sampling
Adaptive observations are
at locations with large background error obtained from the ÒtruthÓ.
