chalmers (sweden), cnrs (france), dwd (germany), gkss (germany), hut (finland), iap bern...
TRANSCRIPT
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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 2000Ground-Based Network
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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
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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
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Overview of Measurements CNN I
Station Microwave IR-Rad. Ceilometer Cloud Radar BALTRAD
Bern xCabauw x xChilbolton x x 94 GHzGeesthacht x 95 GHz xHelsinki x xKiruna xLindenberg x x x xOnsala x xParis x Potsdam x x xSt. Petersburg x 3, 9.6 GHz x
KNMI MIUB Chalmers IFM Vaisala
BBC Workshop Leipzig, May 15-16, 2002
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Overview of Measurements CNN II
Station Microwave IR-Rad. Ceilometer Cloud Radar BALTRAD
Bern xCabauw x x x 3 GHzChilbolton x 94 GHzGeesthacht x 95 GHz xGotland xHelsinki x xKiruna xLindenberg x x x xOnsala x xParis x Potsdam x x xSt. Petersburg x 3, 9.6 GHz xKNMI MIUB Chalmers IFM Vaisala CETP
BBC Workshop Leipzig, May 15-16, 2002
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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 timeresolution, 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
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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 -> = 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 COMMENTSPrecipitation and Cloudiness index from different sources0 - no precipitation (no cloud)1 - precipitaion (cloud) or data value-99. - no data
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Level2 for CNN
BBC Workshop Leipzig, May 15-16, 2002
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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 7.156.514479 268.1 23.1 1310.0 7.256.514491 272.4 23.1 1310.0 7.256.514502 274.5 23.1 1310.0 7.1
BBC Workshop Leipzig, May 15-16, 2002
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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
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Cloud observations in CNN I
BBC Workshop Leipzig, May 15-16, 2002
Station Rain cloudy clear zB Tir LWP IWV Tir LWP 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
cloudy clearzB < 4 km and TIR > 0 C no zB and TIR < -30 C
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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
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BBC Workshop Leipzig, May 15-16, 2002
center of H2O line
cloud sensitive frequency
Comparisons with Radio Sondes
Used for LWP/IWV determination
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LWP for Kiruna April 2001
BBC Workshop Leipzig, May 15-16, 2002
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LWP for Kiruna April 2001
BBC Workshop Leipzig, May 15-16, 2002
Only few liquid water clouds at Kiruna in April 2001
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Russian data during CNN
BBC Workshop Leipzig, May 15-16, 2002
Sun (heating) in the morning + drifts between radiosondes
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Russian data during MICAM
BBC Workshop Leipzig, May 15-16, 2002
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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
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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
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LWP evaluation using IR and Ceilometer
IR-Radiometer Comparison
MIUB (KT19):
= 1 s
= 0.7
KNMI (KT15):
= 10 min
= 2.8
IR-T
em
pe
ratu
re (
MIU
B)
/ °C
IR-T
em
pe
ratu
re (
KN
MI)
/ °C
BBC Workshop Leipzig, May 15-16, 2002
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LWP evaluation using IR and Ceilometer
IR-Radiometer Comparison
Mean IR-Temperature
KNMI / °C
MIU
B /
°C
Maximum IR-Temperature
Minimum IR-Temperature
Station Cabauw CNN II
= 10 min
BBC Workshop Leipzig, May 15-16, 2002
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LWP evaluation using IR and Ceilometer
IR-Radiometer Comparison
Mean IR-Temperature
KNMI / °C
MIU
B /
°C
Maximum IR-Temperature
Minimum IR-Temperature
Station Cabauw BBC
September 1, 2001
= 30 s
BBC Workshop Leipzig, May 15-16, 2002
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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 °CIR-Temperature (KNMI) / °C
IR-T
em
pe
ratu
re (
DW
D)
/ °C
BBC Workshop Leipzig, May 15-16, 2002
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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
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Future Work
23.8 GHz31.4 GHz
BBC Workshop Leipzig, May 15-16, 2002