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 WP 2000 Ground-Based Network

Workpackages WP2000Organisation:“Ground-Based Network“ WP2100Product Definition WP2200CNN I (August/September 2000) WP2300CNN II (April/May 2001) WP2400BBC-Camapign (August/September 2001) WP2500Cloud Processes WP2600Radiometer Design BBC Workshop Leipzig, May 15-16, 2002

Schedule BBC Workshop Leipzig, May 15-16, 2002 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

Overview of Measurements CNN I Station MicrowaveIR-Rad.Ceilometer Cloud Radar BALTRAD Bern x Cabauw x x Chilbolton x x94 GHz Geesthacht x95 GHz x Helsinki x x Kiruna x Lindenberg x x x x Onsala x x Paris x Potsdam x x x St. Petersburg x3, 9.6 GHz x KNMI MIUB Chalmers IFM Vaisala BBC Workshop Leipzig, May 15-16, 2002

Overview of Measurements CNN II Station MicrowaveIR-Rad.Ceilometer Cloud Radar BALTRAD Bern x Cabauw x x x3 GHz Chilbolton x 94 GHz Geesthacht x95 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 x3, 9.6 GHz x KNMI MIUB Chalmers IFM Vaisala CETP BBC Workshop Leipzig, May 15-16, 2002

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) LI (CNN I+II), GE (I), CA (II) Level1b (CNN I) Level1a (CNN II) BBC Workshop Leipzig, May 15-16, 2002

Level2 for CNN BBC Workshop Leipzig, May 15-16, 2002 '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 ','[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 no data

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

Level2 for CNN Quicklooks can be found together with data files! also available as single files over whole campaign e.g. /pub/out/cnn1/level2a/HE_lwp_cnn1_l2a.dat.gz time (days) LWP (gm -2 ) IWV (kgm -2 ) zbase (m) Tir(K) BBC Workshop Leipzig, May 15-16, 2002

Data Volume CNN I + II 55Mcnn1/grab_bag321Mcnn2/grab_bag 611Mcnn1/level0a 1.4Gcnn2/level0a 439Mcnn1/level1a 135Mcnn2/level1a 110Mcnn1/level1b 197Mcnn1/level2a 1.4Gcnn11.9Gcnn2 BBC Workshop Leipzig, May 15-16, 2002

Cloud observations in CNN I BBC Workshop Leipzig, May 15-16, 2002 Station Rain cloudy clear z B T ir LWPIWV T ir LWP IWV (%) (%) (%) (m) (  C) (gm -2 ) (kgm -2 ) (  C) (gm -2 ) (kgm -2 ) BE – – GE HE KI LI ON PA – PO – – SP cloudy clear z B 0 C no z B and T IR < -30 C

Problems BBC Workshop Leipzig, May 15-16, 2002 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 center of H 2 O line cloud sensitive frequency Comparisons with Radio Sondes Used for LWP/IWV determination

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

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

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

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

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

Negative LWP Values: Consequences BBC Workshop Leipzig, May 15-16, 2002 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 conditions deviation due to ill-posed problem in this specific atmospheric situation

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

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

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

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

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

Future Work 23.8 GHz 31.4 GHz BBC Workshop Leipzig, May 15-16, 2002