What can we learn about LSM’s from the ELDAS

increments?

Bart vd Hurk, Janneke Ettema & Pedro Viterbo

A bit about ELDAS

• Soil moisture assimilation ‘the European way’ (corrections using atm RH & T)

• Observed precipitation and radiation

• 15 month pilot study– Oct 1999 – Dec 2000

Design of assimilation system

precipitation

radiation

evaporation

Soil moisturecorrection scheme

Soil moisturecontent

(sub)surfacerunoff

Observations drivingsoil moisture correction

Synops dataMETEOSAT or

MSG

Land surfaceparameterizationscheme

Boundary layerscheme

Validation sites

Validation sites

Validation sites• 20yr ‘PILPS’-climatology (driven by ERA40)• 15mnth CTL with obs P & R• 15mnth DA with obs P & R

Effect of data assimilation

One of dW

Accumulated increment

Change of evaporation

Change of runoff

Change of soil water

A few examples

Ratio increment / (WS)

Apr – Oct 2000

Partitioning of increments

Evaporation RunoffStorage

Apr – Oct 2000

Partitioning of increments

Evaporation RunoffStorage

Apr – Jul 2000

Ranking of E/I

• Nrs in order of rank E/I

• First 10 are found in Mediterranean and Estonia

1 23

4

5 6

7 8

9

10

36

35

34

Limited response of EPrecipitationRunoffStorageEvaporation

Evaporation 1 Apr – 1 Oct

Conclusions

• For many locations increments exceed interannual variability of WS

• For many non-Mediterranean points only a small portion of increments is returned into atmosphere

• Limited response of E in offline runs

• DA gives better evaporation for a few points, but generally only small effect compared to mean bias