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Cabauw Experimental Site forAtmospheric Research
- CESAR -
Henk Klein Baltink
Atmospheric Research Section
27 may 2002 Cloudnet Workshop Paris 2
Outline Overview Instruments at Cabauw Status 35 GHz Cloud Radar examples from BBC-campaign
27 may 2002 Cloudnet Workshop Paris 3
CESAR (Cabauw)
Objective:
to set-up and operate at the Cabauw site an observational facility with a comprehensive set of remote sensing and in-situ equipment to characterize the state of the atmosphere,its radiative properties and interaction with the land surface, for the study of physical processes, climate monitoring, and validation studies
27 may 2002 Cloudnet Workshop Paris 4
Remote Sensing Site
ProfilerSonicGPS
Cabauw Tower
27 may 2002 Cloudnet Workshop Paris 5
Status May 2002 (1) Tower (10, 20, 40, 80, 140, 200 m agl):
wind speed, direction, temp, dew temp (temp also at 0.6,1.6 m) turbulent fluxes at 180 m. (in progress) particle counters (in progress)
Surface: incoming/outgoing short & longwave radiation (BSRN in 20??) rain rate and duration DSD (in progress) soil temp. & hum. turbulent fluxes (at 4.5 m and 1 m. agl)
27 may 2002 Cloudnet Workshop Paris 6
Status May 2002 (2) Remote Sensing (passive)
IR-radiometers microwave radiometer (Univ.-Bonn, until ?)
Remote Sensing (active) 1290 MHz windprofiler/RASS 3.3 GHz FM-CW radar (TARA) 35 GHz Cloud Radar ceilometers (CT75,LD40) 1042 nm lidar GPS-receiver
27 may 2002 Cloudnet Workshop Paris 7
KNMI 35 GHz Radar
CT75 ceilometer
Heimann IR-radiometers
Video camera
27 may 2002 Cloudnet Workshop Paris 8
peak power 100 W (TWT transmitter) polarisation capability on receive spectral processing pulse-coding to enhance sensitivity 1.8 m antenna (0.36º beam angle) flexible parameter setting via GUI automated, unattended operation
Main Characteristics 35 GHz
27 may 2002 Cloudnet Workshop Paris 9
Status 35 GHz Cloud Radar In continuous operation since August 2001 2 week interrupt due to hardware failure (August) some minor software interrupts up to November no calibration and X-pol. (mid January - mid March) power output decreased by 10% since August absolute values not reliable when water on shroud plan 2002: upgrade DSP-board, fast V-H switch
27 may 2002 Cloudnet Workshop Paris 10
Acquisition cycle
0
5000
10000
20 s
BBC
16 s
PRESENT
acquisition
processing
uncoded
coded
coded X-pol
27 may 2002 Cloudnet Workshop Paris 11
Sensitivity
2 modes:- 8-bit code (red)- uncoded (black)
ARM-SGP mode 2-54 dBZe @ 5 km
-42 dBZe @ 5 km
27 may 2002 Cloudnet Workshop Paris 12
Examples from BBC-campaign
TARA
35 GHz
MIRACLE
MICCY
27 may 2002 Cloudnet Workshop Paris 13
Ice Cloud
Reflectivity
Vertical Velocity
27 may 2002 Cloudnet Workshop Paris 14
WaterCloud
27 may 2002 Cloudnet Workshop Paris 15
35 GHz vs. TARA in rain
-70
-60
-50
-40
-30
-20
-10
0
Minutes after start time (00:48:04)
He
igh
t [m
]
KNMI, 19 Sep 2001
10 20 30 40 50 60 70 80
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
-70
-60
-50
-40
-30
-20
-10
0
Minutes after start time (00:48:04)
He
igh
t [m
]
TARA, 19 Sep 2001
10 20 30 40 50 60 70
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Before rain event: good agreement
-30
-20
-10
0
10
20
30
Time [min]
He
igh
t [m
]
35GHz radar
0 30 60 90 120 150 180 210500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
-30
-20
-10
0
10
20
30
Time [min]
He
igh
t [m
]
3.3GHz radar
30 60 90 120 150 180 210500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
During rain event: 20 – 30 dB difference20 50 80 110 140 170 200 230-40
-30
-20
-10
0
10
20
30
40Comparison between TARA and KNMI (Height: 2240m)
Minutes (start time: 05:09UTC)
Ref
lect
ivity
fact
or (
dBZ
)KNMITARA
Onset of precipitation at surface
27 may 2002 Cloudnet Workshop Paris 16
ModelcomparisonBBC 18/9/01
27 may 2002 Cloudnet Workshop Paris 17
Cloud Boundaries?
super cooled layer
27 may 2002 Cloudnet Workshop Paris 18
Ceilometer
Courtesy of Hannelore Bloemink, KNMI
27 may 2002 Cloudnet Workshop Paris 19
Spectra at 17:15
super cooled layer
noise
snr
signal
27 may 2002 Cloudnet Workshop Paris 20
Outlook (to do) Optimize acquisition cycle Calibration procedure (is it accurate
enough?) Mode-intercomparison and merging Water on shroud: no easy solution(?) Analysis of (all that) data