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Chalmers (Sweden), CNRS (France), DWD (Germany),

WP 2000 Ground-Based Network. Chalmers (Sweden), CNRS (France), DWD (Germany), GKSS (Germany), HUT (Finland), IAP Bern (Switzerland), IRE Moscow (Russia), KNMI (The Netherlands), RAL (Great Britain), RPG (Germany), UBonn (Germany). BBC Workshop Leipzig, May 15-16, 2002. Workpackages.

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Chalmers (Sweden), CNRS (France), DWD (Germany),

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  1. WP 2000Ground-Based Network Chalmers (Sweden), CNRS (France), DWD (Germany), GKSS (Germany), HUT (Finland), IAP Bern (Switzerland), IRE Moscow (Russia), KNMI (The Netherlands), RAL (Great Britain), RPG (Germany), UBonn (Germany) BBC Workshop Leipzig, May 15-16, 2002

  2. Workpackages WP2000 Organisation:“Ground-Based Network“ WP2100 Product Definition WP2200 CNN I (August/September 2000) WP2300 CNN II (April/May 2001) WP2400 BBC-Camapign (August/September 2001) WP2500 Cloud Processes WP2600 Radiometer Design BBC Workshop Leipzig, May 15-16, 2002

  3. Schedule Susanne Crewell: Overview of data available from CLIWA-NET measurement campaigns Ulrich Löhnert: Production of level2 data Hannelore Bloemink: Analysis of supercooled water layers GKSS: Investigation of drizzle using radar data Thomas Rose: Status of low-cost radiometer design BBC Workshop Leipzig, May 15-16, 2002

  4. Overview of Measurements CNN I Station Microwave IR-Rad. Ceilometer Cloud Radar BALTRAD Bern x Cabauw x x Chilbolton x x 94 GHz Geesthacht x 95 GHz x Helsinki x x Kiruna x Lindenberg x x x x Onsala x x Paris x Potsdam x x x St. Petersburg x 3, 9.6 GHz x KNMI MIUB Chalmers IFM Vaisala BBC Workshop Leipzig, May 15-16, 2002

  5. Overview of Measurements CNN II Station Microwave IR-Rad. Ceilometer Cloud Radar BALTRAD Bern x Cabauw x x x 3 GHz Chilbolton x 94 GHz Geesthacht x 95 GHz x Gotland x Helsinki x x Kiruna x Lindenberg x x x x Onsala x x Paris x Potsdam x x x St. Petersburg x 3, 9.6 GHz x KNMI MIUB Chalmers IFM Vaisala CETP BBC Workshop Leipzig, May 15-16, 2002

  6. Measured and derived quantities level0: brightness temperatures (MRAD) Infrared temperature (IRAD) cloud base height (BASE) backscatter profile (BSCT) BALTRAD radar reflectivity at station (DBZC) cloud radar reflectivity/velocity/LDR profile (CPR?) azimuth and elevation scans from MRL-5 radar (AZIM,ELEV) level1: liquid water path (LWPP) integrated water path ( ‘‘ ‘‘) temperature profiles (TEMP) humidity profile (HUMI) level2: LWPS (all data from one station with same time resolution, crosschecked, rainflags from different sources) LWC, TEMP + HUMI radar/microwave (Cabauw during BBC) Level1b (CNN I)Level1a (CNN II) LI (CNN I+II), GE (I), CA (II) BBC Workshop Leipzig, May 15-16, 2002

  7. Level2 for CNN 'Liquid Water Content','[gm^2]',1 'Integrated Water Vapor','[kgm^2]',1 'Precipitation from ceilometer < 1 = 0','[mm/h]',1 'Precipitation flag from IR-shutter','[]',1 'Precipitation flag from MICCY-shutter','[]',1 'Precipitation flag from rain gauge','[]',1 'Radar reflectivity factor from BALTRAD < 0 -> = 0 ','[dBZ]',1 'Precipitation flag from Video','[]',1 'Number of cloud bases from ceilometer','[]',1 'Height of lowest cloud base','[m]',1 'Temperature from infrared radiometer','[C]',1 'Cloudiness flag from Video','[]',1 'Other retrieval results indicate problem 1=true','[]',1 %% BEGIN COMMENTS Precipitation and Cloudiness index from different sources 0 - no precipitation (no cloud) 1 - precipitaion (cloud) or data value -99. - no data BBC Workshop Leipzig, May 15-16, 2002

  8. Level2 for CNN BBC Workshop Leipzig, May 15-16, 2002

  9. Level2 for CNN Quicklooks can be found together with data files! also available as single files over whole campaigne.g. /pub/out/cnn1/level2a/HE_lwp_cnn1_l2a.dat.gztime (days) LWP (gm-2) IWV (kgm-2) zbase (m) Tir(K) 56.514468 250.2 23.1 1310.0 7.1 56.514479 268.1 23.1 1310.0 7.2 56.514491 272.4 23.1 1310.0 7.2 56.514502 274.5 23.1 1310.0 7.1 BBC Workshop Leipzig, May 15-16, 2002

  10. Data Volume CNN I + II 55M cnn1/grab_bag 321M cnn2/grab_bag 611M cnn1/level0a 1.4G cnn2/level0a 439M cnn1/level1a 135M cnn2/level1a 110M cnn1/level1b 197M cnn1/level2a 1.4G cnn1 1.9G cnn2 BBC Workshop Leipzig, May 15-16, 2002

  11. Cloud observations in CNN I cloudy clear zB < 4 km and TIR > 0 C no zB and TIR < -30 C Station Raincloudy clear zB TirLWP IWVTirLWP IWV(%) (%) (%) (m) (C) (gm-2) (kgm-2) (C) (gm-2) (kgm-2) BE 4.6 13.5 43.0 – 5.9 104.8 25.3 –36.8 0.9 18.2 GE 9.9 29.5 42.6 1411 8.8 101.3 22.0 -41.8 5.7 14.5 HE 2.7 15.6 41.9 1880 5.2 132.0 23.9 -42.9 1.5 17.2 KI 4.4 37.7 24.3 1360 6.5 108.8 16.4 -37.3 -0.8 12.1 LI 5.6 22.5 34.4 1637 7.6 107.3 25.0 -45.4 -8.5 17.3 ON 10.2 24.1 47.2 1254 7.7 124.1 22.3 -47.9 -8.7 14.9 PA 3.0 26.4 52.7 – 8.8 80.2 26.7 -42.6 -14.7 20.9 PO 3.9 46.8 45.3 1599 – 69.8 23.5 – -11.6 18.9 SP 6.2 13.2 40.3 806 8.2 128.6 23.7 -45.9 55.0 16.8 BBC Workshop Leipzig, May 15-16, 2002

  12. Problems • Ceilometer cloud bases from Onsala in ft • Microwave radiometer in Geesthacht during CNN II •  analyis only for case studies • Uncertainty of gas absorption is about as high as differences between different radiometer (MICAM) • No microwave calibration possible in April 2001 at Kiruna •  IWV from GPS, cloud detection • Russian data LWP/IWV are not reliable • Negative LWP values • Averaging of infrared temperature BBC Workshop Leipzig, May 15-16, 2002

  13. Comparisons with Radio Sondes center of H2O line cloud sensitive frequency Used for LWP/IWV determination BBC Workshop Leipzig, May 15-16, 2002

  14. LWP for Kiruna April 2001 BBC Workshop Leipzig, May 15-16, 2002

  15. LWP for Kiruna April 2001 Only few liquid water clouds at Kiruna in April 2001 BBC Workshop Leipzig, May 15-16, 2002

  16. Russian data during CNN Sun (heating) in the morning + drifts between radiosondes BBC Workshop Leipzig, May 15-16, 2002

  17. Russian data during MICAM BBC Workshop Leipzig, May 15-16, 2002

  18. Negative LWP values low noise leads to high relative accuracy mean over many atmospheric situations daily bias due to ill-posed problem BBC Workshop Leipzig, May 15-16, 2002

  19. Negative LWP Values:Consequences • Analysis of whole campaigns (2 months) eliminate mean bias (over two months) deviation from zero in cloud free cases due to uncertainty in gas absorption or miscalibration • shorter case studies (one or two days) adjust LWP according to trend in cloud free conditionsdeviation due to ill-posed problem in this specific atmospheric situation BBC Workshop Leipzig, May 15-16, 2002

  20. LWP evaluation using IR and Ceilometer IR-Radiometer Comparison MIUB (KT19):  = 1 s  = 0.7 IR-Temperature (MIUB) / °C IR-Temperature (KNMI) / °C KNMI (KT15):  = 10 min  = 2.8 BBC Workshop Leipzig, May 15-16, 2002

  21. LWP evaluation using IR and Ceilometer IR-Radiometer Comparison Mean IR-Temperature Maximum IR-Temperature MIUB / °C KNMI / °C Minimum IR-Temperature Station Cabauw CNN II  = 10 min BBC Workshop Leipzig, May 15-16, 2002

  22. LWP evaluation using IR and Ceilometer IR-Radiometer Comparison Mean IR-Temperature Maximum IR-Temperature MIUB / °C KNMI / °C Minimum IR-Temperature Station Cabauw BBC September 1, 2001  = 30 s BBC Workshop Leipzig, May 15-16, 2002

  23. LWP evaluation using IR and Ceilometer IR-Radiometer Comparison DWD (KT15):  = 1 s t = 8.5 min  = 5  =21.9 °C IR-Temperature (DWD) / °C KNMI (KT15):  = 10 min t = 10 min  = 2.8  =21.1 °C IR-Temperature (KNMI) / °C BBC Workshop Leipzig, May 15-16, 2002

  24. Future Work • Changes necessary to level2a products ? • Synergetic algorithms MRAD+IRAD+BASE only lead to minor improvement in LWP  robust algorithms are more important • Analysis of regional network during BBC • Gas absorption at microwave frequencies is uncertain compute brightness temperatures from model output • Compute cloud fraction and daily cycle of cloud parameters • LWC for selected days from GKSS/MPI radar and MICCY during CNN I ? BBC Workshop Leipzig, May 15-16, 2002 BBC Workshop Leipzig, May 15-16, 2002

  25. Future Work 23.8 GHz31.4 GHz BBC Workshop Leipzig, May 15-16, 2002

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