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CARPE DIEM WP 7: FMI Progress Report

CARPE DIEM WP 7: FMI Progress Report. Jarmo Koistinen, Heikki Pohjola Finnish Meteorological Institute. Area 1/WP3: Development of a variational assimilation scheme for doppler winds (FMI + SMHI, responsible persons at FMI Heikki Järvinen, Kirsti Salonen)

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CARPE DIEM WP 7: FMI Progress Report

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  1. CARPE DIEMWP 7: FMI Progress Report Jarmo Koistinen, Heikki Pohjola Finnish Meteorological Institute

  2. Area 1/WP3: Development of a variational assimilation scheme for doppler winds (FMI +SMHI, responsible persons at FMI Heikki Järvinen, Kirsti Salonen) • Area 2/WP7: Advanced surface precipitation estimate from radars and a NWP model (HIRLAM) (Jarmo Koistinen, Heikki Pohjola) • Objective: Improve the accuracy and quality of operational real time precipitation measurements

  3. WP 7.3 Vertical reflectivity profile correction applying radars and NWP • New order: 7.3 started first and continues during the whole 36 months. WPs 7.1-7.2 started later and feed 7.3. • Operational method has been created and validated (preliminary presentations at ERAD and AMS Radar Conferences, Heikki’s MSc), a final paper should be written. Remaining problem: OP i.e. WP 7.2. • Results applied in the GPM-project validation planning

  4. Measured vertical profile of reflectivity • 7 C-band radars • every 15 minutes • layer thickness 200 m • range 2 - 40 km • max bin count 5000 / layer 1(2)

  5. Statistics of VPR from March 2001 to August 2003 (556 471 profiles) 1(2)

  6. Climatological profiles based on precipitation profiles March 2001 to August 2003

  7. VPR correction 1(2)

  8. Yearly average VPR correction 1(2)

  9. Validation of the VPR correction with overlapping radars • Precipitation profile measured at Radar 2 • > 50 measurement bins in the same location diagnosed as precipitation (max. 10020) • Difference in those bins (Rad 2 – Rad 1) tells under/over estimation at the distance Rad 2 • Average bias and standard deviation calculated for distances 141 km, 180 km, 193 km, 198 km and 219 km. Measurement area 5 – 15 km 1(2)

  10. Radar pair Anjalankoski-Vantaa (Vantaa-Anjalankoski) Feb – May 2003, distance 141 km

  11. Radar pair Korppoo-Vantaa (Vantaa-Korppoo) Feb – May 2003, distance 180 km

  12. Radar pair Ikaalinen-Vantaa (Vantaa-Ikaalinen) Feb – May 2003, distance 193 km

  13. Radar pair Ikaalinen-Korppoo (Korppoo-Ikaalinen) Feb – May 2003, distance 198 km

  14. Radar pair Kuopio-Utajärvi (Utajärvi-Kuopio) Feb – May 2003, distance 219 km

  15. Radar pair Vantaa-Ikaalinen (Ikaalinen-Vantaa) Jun – Aug 2003, distance 193 km • Calibration difference on Vantaa (+ 2-3 dB) and lowest elavation angle 0.8 instead of 0.4 on Ikaalinen because of technical reason (-2 dB)

  16. Correction with different measurement angles Snow profile Rain profile with bright band 2 dB

  17. Nordrad Quality Assurance project • Calibration difference for radar pair Vantaa Ikaalinen, period Jun – Aug 2003

  18. WP 7.1: Attenuation correction based on 3D water phase diagnosis from NWP model quantities • Deliverables: • Large attenuation statistics for rain-only (assumed in most existing radar systems) and variable water phase statistics • Improvement in surface precipitation • Overestimation of attenuation in hail avoided by applying a hail algorithm

  19. Calculation of attenuation • Simple one: all precipitation is liquid, k(dB/km)=1.12*10-4 Ze0.62 • Advanced one: freezing level height fixed at each radar, obtained from NWP and VPR, attenuation calculated separately in each water phase layer • We are testing Doppler data from elevation angle 90 degrees in the polar volume scans to improve the radar-based detection of freezing level • Formula: rain (see above), dry snow (in Battan), bright band ?

  20. WP 7.2 Elimination of overhanging precipitation (OP) from surface estimates Altostratus: present in 15 % of all VPR in Finland in 2001

  21. Diagnosis of OP in the network • Apply precipitation base height field from the radar network • Apply (an idea so far): nowcast movement of theVPR, measured above the radars with the analysed motion vector field (operationally available) • Apply precipitating layers from NWP. First step: compare model profiles from HIRLAM with VPR from radars. Available quantities e.g. RH, and cloud condensate mixing ratio.

  22. Example of OP case 9.3. 2002 02 UTC

  23. 9.3. 2002 03 UTC

  24. 9.3. 2002 04 UTC

  25. 9.3. 2003 05 UTC

  26. 9.3. 2003 06 UTC

  27. 9.3. 2003 07 UTC

  28. Overhanging precipitation 9.3. 2002 at Anjalankoski radar 1(2)

  29. 1(2)

  30. 1(2)

  31. 1(2)

  32. 1(2)

  33. 1(2)

  34. 1(2)

  35. 1(2)

  36. 1(2)

  37. 1(2)

  38. 1(2)

  39. 1(2)

  40. 1(2)

  41. 1(2)

  42. 1(2)

  43. 1(2)

  44. 1(2)

  45. 1(2)

  46. 1(2)

  47. HIRLAM model relative humidity 09.03. 2003

  48. HIRLAM model freezing level height 21.8. 2003 17 UTC

  49. 24 h accumulated precipitation Nov 8, 2002, 23 UTC No VPR correction No VPR correction 1(2)

  50. 24 h accumulated precipitation Nov 7, 2002, 14 UTC No VPR correction With VPR correction 1(2)

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