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Soil moisture generation at ECMWF

Soil moisture generation at ECMWF. Gisela Seuffert and Pedro Viterbo European Centre for Medium Range Weather Forecasts. ELDAS Interim Data Co-ordination Meeting 17./18.09.2003. Action: no further development. Action: in production. Action: SCM test runs. Action: 2 papers:

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Soil moisture generation at ECMWF

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  1. Soil moisture generation at ECMWF Gisela Seuffert and Pedro Viterbo European Centre for Medium Range Weather Forecasts ELDAS Interim Data Co-ordination Meeting 17./18.09.2003

  2. Action: no further development Action: in production Action: SCM test runs • Action: • 2 papers: • published in GRL (T,RH,Tb) • Cond. accepted at JHM (OI, EKF) Action: still pending Plans ( ELDAS 1st progress meeting) Assimilation aspects: • Minimize the combined errors in prediction of soil moisture, latent heat flux and screen level observations • Further mw-Tb assimilation experiments (viewing angle, times) • Assimilation of heating rates Technical aspects: • Paper(s) focusing on the - new features of assimilation method - assimilation of mw-Tb - (assimilation of heating rates) • Summer 2003: Build production system for the annual data base • End of 2003: Start production

  3. Soil moisture analysis systems Optimal Interpolation: • Used in the operational ECMWF-forecast since 1999 (Douville et al., 2000) • Fixed statistically derived forecast errors • Criteria for the applicability of the method - atmospheric and soil exceptions - corrections when T and RH error are negatively correlated • Extended Kalman Filter: • Used in the operational DWD- • forecast since 2000 (Hess, 2001) * • Updated forecast errors • Criteria for the applicability of the method • - no ‘direct’ atmospheric exceptions • - soil exceptions still to be tested • * Changes: • - Assimilation of 2m- T and RH, mw-Tb • Model forecast operator accounts for water transfer between soil layers • Test adaptive EKF

  4. Experiment Design Atm. initial conditions + dynamics forcing from ECMWF reanalysis (ERA40) Single-column model of the ECMWF NWP model + microwave emissivity model Observation of precipitation + radiation Increments (daily) First guess: T2m,RH2m,HR(?) Soil moisture analysis scheme OI or Extended Kalman Filter Observations: T2m,RH2m,HR Soil moisture Background error

  5. Production system for soil moisture Starting point: • Experiments based on Single Column version of the ECMWF’s NWP model (SCM) Requirements: • 0.2 x 0.2 regular lat/lon grid for Europe (15W-38E, 35N-72N) • Computer time (cost efficiency) • Annual database for 1.10.1999 – 31.12.2000  control system Solutions: Add 1: run n x n SCMs over Europe (each SCM runs independently) Add 2: - run SCMs only for land points (about 25 000 SCMs) - I/O consideration - High degree of parallelisation in an easy way  balance saving of computer time and time for programming Add 3: Supervisor Monitor Scheduler (SMS)

  6. Production system for soil moisture(2) Progress of work: • Changes to the SCM source code • SCM structure has been changed to run n x n SCMs in one run (single point  area) • I/O netcdf  I/O grib • OpenMP parallelization (up to 8 processes on one thread) • Changes to the soil moisture analysis (SMA) • SMA has been changed to run n x n points in one run • I/O netcdf  I/O grib • Forcing data • Composition of forcing data changed from one point to n x n points • O netcdf  O grib • Control Structure • First SMS layout

  7. Get forcing data from Mars archive • Prepare data for SCM INPUT 1) Background run • Get forcing data from Mars archive • Prepare data for SCM INPUT • Soil moisture perturbation • Soil temperature perturbation 1) Soil moisture analysis • Final (soil moisture) trajectory • Check success of SMA (Costfunctions) • Soil temperature analysis • Final (soil temperature) trajectory • Check success of STA (costfunctions) • Forecast run

  8. Production system for soil moisture (3) • What is still missing? • Interpolation from gaussian grid to reg. 0.2 x 0.2 lat/lon grid • Incorporation of ELDAS maps (e.g. land cover) • Incorporation of ELDAS forcing data (precipitation, radiation) • Archiving of output in MARS • Observation (Re-analysis) data of 2mT and 2mRH for SMA +STA • Post-processing routines for parameters especially asked for by ELDAS validation • ECMWF orography problems (LW) • Final tests

  9. Time schedule(1) • Estimated Production Time: • Analysis for one day: • - one SCM run for 1000 pixels needs 5 min on 8 nodes  ~ 2 hours for 25000 pixels • - 5 x SCMs are needed  10 hours for 25000 pixels • approx. 5-6 months for annual database • further parallelization needed (splitting Europe into boxes) (MPI, distributed memory)

  10. Time schedule(2) Expected Start of production: ? • Under normal circumstances: • 6 weeks required to include missing bits and pieces • 2 weeks final tests • Start production by November/December

  11. Assimilating SHR, T+RH, T+RH+SHR Days when SHR is available (50% data missing, 25% cloudy) Soil moisture • Variable SHR observation error depends on cloud fraction flag (how many hours are cloud free): • cloud fraction flag of neighbouring pixels • cloud fraction flag of pixel

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