Assimilation of Globsnow data into HIRLAM. Mostamandy Suleiman Sodankyla August 2011

Transcription

1 Assimilation of Globsnow data into HIRLAM Mostamandy Suleiman Sodankyla August 2011

2 Motivation Small number of observations (especially in eastern Europe and Russia) 00 cm of snow problem Non-uniform in time distribution of SYNOP snow observations

3 00 cm of snow problem Many stations do not report 00 cm snow Information spreads from existing stations into the area of no observations Snow edge is difficult to analyze

4 Distribution of SYNOP snow observations 00UTC 12UTC 06UTC 18UTC

5 Main Goal To improve data coverage To solve 0cm problem (Snow edge) To make distribution of snow observations more uniform in time To improve quality of forecast (T2M, RH2M, )

6 Globsnow

7 Globsnow Spaceborne passive microwave radiometer data combined with ground-based synop observations 25km spatial resolution Time resolution once per day Temporal coverage NRT (near-real-time) service ongoing Reference: Pulliainen J Mapping of snow water equivalent and snow depth in boreal and subarctic zones by assimilating space-borne microwave radiometer data and ground-based observations. Remote Sensing of Environment, Vol. 101, pp )

8 Globsnow Globsnow products Snow Water Equivalent (SWE) Snow Extent (SE) Output Formats 1. HDF (only data without coordinate) 2. NetCDF ( data + coordinate) 3. PNG ( Quick look )

9 Quality of data 2009

10 Quality of data 2009

11 Quality of data 2010

12 Quality of data 2010

13 Quality of data 2010

14 Quality of data 2010

15 Technical aspects Reading globsnow data Converting hdf to ascii Converting netcdf to ascii ( not yet ) Preparing file for SPAN Converting the ascii file into specob format Converting SWE to SD using (ρsnow =0.24) Modyfing SPAN Code cntrol.f getobs.f seterr.f setlim.f setoip.f siodev.f specob.f, Span script

16 Design of the experiments Hirlam version Latest 7.3 version New surface scheme ( newsnow ) Resolution 0.15 deg., 60 levels 3DVAR Time 15.Oct 24.Dec Mar 27. Apr Nov 20 Dec 2010 Globsnow observations Use them when available, some days with missing Globsnow file If exist, use the same file for every cycle of the day for winter they are available near real time (only one day is missed) Resolution of the globsnow data: ~25km, comparable to the grid box size

17 Different data scenarios More than 30 exp. have been done Reference: only SYNOP observations Globsnow data, elevation from gtopo (high resolution) Globsnow data using HIRLAM orography Globsnow data in addition to the reference Globsnow data without SYNOP data Globsnow data only at 00 UTC without synop Globsnow thinned 4 times (to 75 km) Results from last experiments (2010) are shown Reference Globsnow without synop Globsnow + synop Reduced resolution of globsnow Globsnow assimilated once per day

18 Results 27 March 2010

19 results 10 April 2010

20 Results 25 April 2010

21 Results 20 November 2010

22 Results 15 December 2010

23 Results 20 December 2010

24 Results

25 Results Forecast verification Dec.2010

26 Results Forecast verification April.2010

27 Results Forecast verification April.2010 SNOW_73_SWGO TYPE LL BIAS RMSE STDV TT TT TT TT TT TT All SNOW_73_SWSG N BIAS RMSE STDV SNOW_73_ref_SPRING_2010 N BIAS RMSE STDV N

28 Results Forecast verification April.2010

29 Conclusions, problems and plans Data from Globsnow to SPAN technical problems are solved The autumn and spring experiments has been examined The snow extant is reasonable in Globsnow Snow depth underestimated in some area No snow on mountains No independent observation to verify against Globsnow data can be used together with synop data or separately? Globsnow can be used only once The quality of forecast not much depend on resolution of Globsnow data (25 -> 75) Changing R(obs. err.) matrix for Globsnow data Quality control for Globsnow data. Writing fortran interface to converting globsnow data form netcdf to ASCII Defining the new correlation function for Globsnow data