Chalmers (Sweden), CNRS (France), DWD (Germany), GKSS (Germany), HUT (Finland), IAP Bern (Switzerland), IRE Moscow (Russia), KNMI (The Netherlands), RAL

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

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


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

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


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


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)


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 COMMENTSPrecipitation and Cloudiness index from different sources0 - no precipitation (no cloud)1 - precipitaion (cloud) or data value-99. - no data

Level2 for CNN


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


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


Cloud observations in CNN I


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

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


center of H2O line

cloud sensitive frequency

Comparisons with Radio Sondes

Used for LWP/IWV determination

LWP for Kiruna April 2001


LWP for Kiruna April 2001


Only few liquid water clouds at Kiruna in April 2001

Russian data during CNN


Sun (heating) in the morning + drifts between radiosondes

Russian data during MICAM


Negative LWP values


daily bias due to ill-posed problem

low noise leads to high relative accuracy

mean over many atmospheric situations

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 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-T

em

pe

ratu

re (

MIU

B)

/ °C

IR-T

em

pe

ratu

re (

KN

MI)

/ °C




Mean IR-Temperature

KNMI / °C

MIU

B /

°C

Maximum IR-Temperature

Minimum IR-Temperature

Station Cabauw CNN II

= 10 min




Mean IR-Temperature

KNMI / °C

MIU

B /

°C

Maximum IR-Temperature

Minimum IR-Temperature

Station Cabauw BBC

September 1, 2001

= 30 s




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


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

Future Work

23.8 GHz31.4 GHz


Documents

Chalmers (Sweden), CNRS (France), DWD (Germany), GKSS (Germany), HUT (Finland), IAP Bern (Switzerland), IRE Moscow (Russia), KNMI (The Netherlands), RAL