1. General Meeting Moscow, 6-10 September 2010 High-Resolution verification for Temperature ( in northern Italy) Maria Stefania Tesini COSMO General Meeting 6-10 September 2010 Moscow

2. General Meeting Moscow, 6-10 September 2010 Domain and dataset SYNOP STATION REGIONAL NETWORK Models involved in this verification are COSMO-I7 (in different configuration), COSMO-I2, det.CLEPS and IFS-ECMWF for comparison

3. General Meeting Moscow, 6-10 September 2010 Motivation The choice of the verification domain depends on the that we started the verification over the region where we work The choice of the verification domain depends on the fact that we started the verification over the region where we work We focus on this area, even if we can extend the verification to the rest of Italy, because the results on 2m temperature seems to be peculiar of this region High resolution network allows to group stations with same characteristics (e.g. height of the station) in order to perform significant statistics

4. General Meeting Moscow, 6-10 September 2010 One of the peculiarity… Spring 2007: Spring 2007: COSMO-I7 didn’t forecast temperature below zero despite some observed frosts in the Po valley The “0 °C” threshold has a physical meaning so is more noticeable, but the overestimation in the early morning happens at all temperature ranges and in all the seasons

5. General Meeting Moscow, 6-10 September 2010 Another peculiarity… In valley stations the MAE of COSMO-I7 00UTC run at 3UTC and 6UTC decrease with the increasing of the forecast time d1 d2 d3

6. General Meeting Moscow, 6-10 September 2010 In the other stations, for other forecast time and for 12UTC run fortunately the error follow “the right order”, even if the difference among the lines are small d1 d2 d3

7. General Meeting Moscow, 6-10 September 2010 T2m COSMO-I7: SON2009

8. General Meeting Moscow, 6-10 September 2010 T2m Other models: SON2009

9. General Meeting Moscow, 6-10 September 2010 T2m COSMO-I7 00UTC: LAST YEAR

10. General Meeting Moscow, 6-10 September 2010 T2m COSMO-I7 00UTC: WINTER SEASON

11. General Meeting Moscow, 6-10 September 2010 Remarks on COSMO-I7 errors features Different configuration of COSMO-I7 behave in a very similar way Errors depend on seasons but the same season presents different errors in different years Dependence on height of the stations, in particular for bias –In stations: overestimation from 18 UTC to 6 UTC, sudden underestimation from 9 UTC to 15 UTC –In valley stations: overestimation from 18 UTC to 6 UTC, sudden underestimation from 9 UTC to 15 UTC –In other stations: the cycle seems to be the same as valley station but shifted towards negative value, masking some errors No relevant difference between 00UTC and 12UTC runs, a part for the error at the start of 00UTC run

12. General Meeting Moscow, 6-10 September 2010 Trying to understand the problems… 1. 1. Test (or Experimental) suite: how the nudging of 2m Temperature (from synop stations) impact on the forecast? [in the operational version only the dew-point temperature is assimilated…] 2. 2. Observed weather conditions in the Po valley: do temperature forecast errors depend on the type of weather?

13. General Meeting Moscow, 6-10 September 2010 COSMO-I7/Test suite “day by day” errors: T2m - FCT+00 - 00UTC  COSMO-I7  TEST  ECMWF

14. General Meeting Moscow, 6-10 September 2010 Some remarks on COSMO-I7/Test suite “day by day” errors at +00 fcst The impact of 2mT assimilation is very evident in valley stations: – –the bias is considerably reduced by T2m assimilations – –since the bias is mainly positive, the MAE is reduce consequently reduced In the stations above 100m the impact is non particularly evident

15. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 T2m – FCT +00  +72 step 3h

16. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 Td2m – FCT +00  +72 step 3h

17. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 RH – FCT +00  +72 step 3h

18. General Meeting Moscow, 6-10 September 2010 Remarks on Cosmo-I7 / test suite for SON2009 2m Temperature positive impact of the 2m temperature only for the first 6-9 hours of forecast and mainly in valley stations no significant differences between the two versions for stations above 100 m and for the following forecast steps 2m Dew-point Temperature Significant differences in bias. The test-suits tends to become more “dry” increasing the forecast time Test-suite MAE is better for the first day of forecast, than tends to get worse especially for station above 100 m 2m Relative Humidity Confirm the test-suite tendency to become more “dry” with forecast time a worsening of test-suite MAE for stations below 100 m is observed, while for other stations the differences are small

19. General Meeting Moscow, 6-10 September 2010 Is there an impact on precipitations? Verification performed comparing the forecast and observed mean (or maximum) in squared boxes The stations are more ore less the same used for temperature verification

20. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 TP – FCT +00  +72 step 6h COSMO-I7 Mean > 1 mm/6h

21. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 TP – FCT +00  +72 step 6h TEST SUITE Mean > 1 mm/6h

22. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 TP – FCT +00  +72 step 6h Mean > 5 mm/6h COSMO-I7

23. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 TP – FCT +00  +72 step 6h TEST SUITE Mean > 5 mm/6h

24. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 TP – FCT +00  +72 step 6h MAX > 10 mm/6h COSMO-I7

25. General Meeting Moscow, 6-10 September 2010 Cosmo-I7 / test suite SON2009 TP – FCT +00  +72 step 6h TEST SUITE MAX > 10 mm/6h

26. General Meeting Moscow, 6-10 September 2010 Remarks on Cosmo-I7 / test suite for SON2009 Precipitation Positive impact for the first 12 hours of forecast for low thresholds Negative impact for high thresholds in terms of POD General decrease in FAR joined to reduction of BIAS

27. General Meeting Moscow, 6-10 September 2010 Summary on Cosmo-I7 / test suite comparison The assimilation of T2m improve the forecast only in the first 6-12 hours In the following steps the forecasts get worse, especially for variable related to humidity (Td, RH, precipitation) We need further investigation on how surface parameters such as T2m and TD2m propagate to higher layer

28. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley Days are classified on the basis of the observed weather conditions in plain region in a subjective way They are divided in 4 classes: – –Clear – –Partly cloudy – –Mostly cloudy/Cloudy – –Rain/Snow Verification has been performed for days in each group

29. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: daily time series T2m OBSERVED T2m COSMO-I7 T ground COSMO-I7 MEAN TEMPERATURE of valley stations

30. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – COSMO-I7 00 UTC 29 days 15 days 10 days 38 days 92 days The groups are made using weather conditions in plain region

31. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – COSMO-I7 00 UTC

32. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – ECMWF 00 UTC

33. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – COSMO-I7 12 UTC

34. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – DetCLEPS 12 UTC

35. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – DetCLEPS-test

36. General Meeting Moscow, 6-10 September 2010 Observed weather conditions in the Po valley: MAM2010 – ECMWF 12 UTC

37. General Meeting Moscow, 6-10 September 2010 Remarks on “Observed weather conditions in the Po valley” Verification show a strong dependence of errors on weather conditions in valley region Model perform better when is raining or cloudy and worst when is clear The stratification of the errors is very evident also in “other stations” – note that the selection of the weather condition is based on the weather in plain region

38. General Meeting Moscow, 6-10 September 2010 CONCLUSION The assimilation of T2m improve the forecast only in the first 6-12 hours, but in the following hours the forecasts get worse, especially for variable related to humidity (Td, RH, precipitation) Weather conditions in Po valley influence the magnitude of errors in Temperature Which are the parameters involved? – –Soil moisture, radiation, heat fluxes….? Ideas?

39. General Meeting Moscow, 6-10 September 2010 Thank you for yor attention