¥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.