The standard procedures for verification of surface variables are defined in the Manual on the Global Data-processing and Forecasting System: Annex IV to the WMO Technical Regulations (available from WMO library at https://library.wmo.int/index.php?lvl=notice_display&id=12793), appendix 2.2.34.
ECMWF in the capacity of LC DNV collects and archive the scores. Data are exchanged in an ASCII-based format which is simple but flexible and is similar to the format used WMO exchange of domain-averaged upper-air scores.
Resources
- The format of the reports of the station-based verification scores.
- The procedures for the exchange of (surface) verification reports.
- The remarks on the implementation of the surface verification reports at ECMWF.
- Answered Questions on the surface verification exchange
Data format
VBar-delimited format
centre | model_id | yyyymm | time | forecast_step | station_id | latitude | longitude | station_elevation | parameter | level | period | score | event | sample_size | mean_value
where
- 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 (variable-length string) 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 time (in hours UTC) when the forecasts included in the mean have been validating;
- forecast_step is the length of the forecast (in hours);
- station_id is the name and/or numeric 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;
- station_elevation is the elevation of the observation station above the mean sea level in meters;
- parameter is the parameter and level of the verified model parameter:
| parameter | description |
|---|---|
| t2m | air temperature at 2 meters above the model orography surface and corrected to the actual station elevation using the constant lapse rate 6.5K/1000m |
| tp24 | total precipitation accumulated over previous 24 hours |
| ff10m | wind speed at 10 meters above the model orography |
- score is the name of the verification score or statistic:
| score | description | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| me | mean error (bias), computed as forecast minus observation | |||||||||
| ct | contingency table, the 4 values are misses, hits, correct non-events, and false alarms (in this order)
|
- event is the name of the event (for contingency tables)
| event | description |
|---|---|
| val>1 | forecast/observed value greater than 1 unit of the forecast parameter |
| an>4 | forecast/observed anomaly with respect to the station climate mean greater than 4 units of the forecast value |
| an<-1.5std | forecast/observed anomaly with respect to the station climate mean less than -1.5 times the standard deviation of the climate at the observation station |
- 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; in case of contingency table these are the 4 values delimited by comma