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High-Resolution verification for Temperature ( in northern Italy)

High-Resolution verification for Temperature ( in northern Italy). Maria Stefania Tesini COSMO General Meeting 6-10 September 2010 Moscow. Domain and dataset. SYNOP STATION. REGIONAL NETWORK.

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High-Resolution verification for Temperature ( in northern Italy)

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

  2. 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 General Meeting Moscow, 6-10 September 2010

  3. Motivation • 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 General Meeting Moscow, 6-10 September 2010

  4. One of the peculiarity… • 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 General Meeting Moscow, 6-10 September 2010

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

  6. •d1 •d2 •d3 • 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 General Meeting Moscow, 6-10 September 2010

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

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

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

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

  11. 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 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 General Meeting Moscow, 6-10 September 2010

  12. Trying to understand the problems… • 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…] • Observed weather conditions in the Po valley: do temperature forecast errors depend on the type of weather? General Meeting Moscow, 6-10 September 2010

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

  14. 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 General Meeting Moscow, 6-10 September 2010

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

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

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

  18. 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 General Meeting Moscow, 6-10 September 2010

  19. 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 General Meeting Moscow, 6-10 September 2010

  20. Cosmo-I7 / test suite SON2009TP– FCT +00  +72 step 6h COSMO-I7 Mean > 1 mm/6h General Meeting Moscow, 6-10 September 2010

  21. Cosmo-I7 / test suite SON2009TP– FCT +00  +72 step 6h TEST SUITE Mean > 1 mm/6h General Meeting Moscow, 6-10 September 2010

  22. Cosmo-I7 / test suite SON2009TP– FCT +00  +72 step 6h COSMO-I7 Mean > 5 mm/6h General Meeting Moscow, 6-10 September 2010

  23. Cosmo-I7 / test suite SON2009TP– FCT +00  +72 step 6h TEST SUITE Mean > 5 mm/6h General Meeting Moscow, 6-10 September 2010

  24. Cosmo-I7 / test suite SON2009TP– FCT +00  +72 step 6h COSMO-I7 MAX > 10 mm/6h General Meeting Moscow, 6-10 September 2010

  25. Cosmo-I7 / test suite SON2009TP– FCT +00  +72 step 6h TEST SUITE MAX > 10 mm/6h General Meeting Moscow, 6-10 September 2010

  26. 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 General Meeting Moscow, 6-10 September 2010

  27. 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 General Meeting Moscow, 6-10 September 2010

  28. 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 General Meeting Moscow, 6-10 September 2010

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

  30. Observed weather conditions in the Po valley: MAM2010 – COSMO-I7 00 UTC The groups are made using weather conditions in plain region 29 days15 days10 days38 days92 days General Meeting Moscow, 6-10 September 2010

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

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

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

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

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

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

  37. 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 General Meeting Moscow, 6-10 September 2010

  38. 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? General Meeting Moscow, 6-10 September 2010

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

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