At the WMO Commission for Basic Systems (CBS) ET-OWFPS Meeting on 22-24 October 2014 in Geneva, a draft document on standardized surface verification of deterministic NWP products was agreed. The document specifies the content of the future exchange of surface scores between global centres and is available here:     Standardized Surface Verification for Deterministic NWP.

ECMWF will be collecting and archiving the scores. Data will be exchanged in an ASCII-based format which is simple but flexible and is similar to the format used WMO exchange of upper-air scores.

Data format

Data file consists of score values and corresponding metadata in an ASCII format.

Every score value is described by the full set of key attributes, like its parameter, station id, month, step etc. Parameters describing one score value at one station are organised into a record. Each record corresponds to one score value. A record is a collection of pairs key=value separated by commas. A record spans one line. Value of the key which is not given in the current record is inherited from the previous record, except for the value parameter v which has to be present in each record.

Each A record has the following format:

If the value is not available the record either should not be given at all or the value should be set to NIL (v=nil); every record must contain the key v (value of key v is not inheritable from previous record)of any key is unknown it is encoded as "na". However, every record has to have a valid mean_value (the "v" key); if the value is not known such record should not be included in the data file.

Example

centre=ecmf,model=hr_0001,d=201602,t=00,s=1200,st=97146,lat=-4.1,lon=122.43,lam=-4.147,lom=122.484,se=50,me=1599163,par=tcc,sc=ct,th=2/6,n=28,v=0/0/0/0/0/7/0/0/21
s=3,v=0/0/0/0/0/4/0/0/24
s=6,v=0/10/0/10/50/2/0/60/1326
t=12,s=12,n=22v=0/0/0/0/0/6/0/0/22
s=15,v=0/0/0/0/0/3/0/0/25
s=18,v=0/0/0/10/20/14/0/7/11

...

0/24
t=00,s=0,sc=mae,th=na,v=60.92
s=3,v=59.92
s=6,v=62.01
t=12,s=12,v=60.59
s=15,v=59.81
s=18,v=62.08
t=00,s=0,sc=me,v=-60.92
s=3,v=-59.92
s=6,v=-62.01
s=9,n=26,v=-66.37
...

Values of keys

• centre (4-characters string) is the WMO identifier of the originating centre (ammc, cwao, ecmf, edzw, egrr, kwbc, lfpw, rjtd, rksl, rums etc);

• model_id (a string , not containing a comma or vertical bar) is free model identifier assigned by the originating centre (to distinguish between potentially different models provided by the centre);

• yyyymm is the month of the mean, where yyyy is the year and mm is the month (01-12);
• time is the validity time (in hours UTC) of the forecasts verified;
• forecast_step is the length of the forecast (in hours);
• station_id (a number) is the WMO ID of the observation station verifying the forecasts;
• latitude is the latitude of the observation station verifying the forecasts;
• longitude is the longitude of the observation station verifying the forecasts;
• model_grid_latitude (non-mandatory) is the latitude of the model grid point used to extract the forecast at the observation location;
• model_grid_longitude (non-mandatory) is the longitude of the model grid point used to extract the forecast at the observation location;
• station_elevation is the elevation of the observation station above the mean sea level in meters;
• model_orography_elevation is the elevation of the model orography at the observation location; if the model orography changed during the month (due to a model upgrade etc) the value corresponding to the orography of the last forecast in the month should be given here;
• parameter is the verified model output parameter:

...

• sample_size is number of observations used to compute the monthly mean at the given station;
  
• mean_value is the value or values of the score mean computed based on the forecast initiating at time time UTC, verifying in the month yyyymm, for the forecast length forecast_step hours; in case of nxn n_xn contingency table these are the n² values delimited by forward slashes (see the score table above)

...