Cloudnet Observing Stations
Instrumentation
C L Wrench
Cloudnet Final Symposium – 12 October 2005
Cloud Remote Sensing Stations
Cloudnet Final Symposium – 12 October 2005
Cloudnet started with three cloudobserving stations:
(1) Cabauw, The Netherlands[51.971N, 4.927E]
(2) Chilbolton, United Kingdom[51.145N, 1.437W]
(3) SIRTA-Palaiseau, France[48.713N, 2.204E]
Each CRS station had been developed over a number of years prior to 2001 with national funding.
The instrumentation available at each site was different.
CRS - CABAUW
Cloudnet Final Symposium – 12 October 2005
View from the 213m tower towards the remote sensing site
Cabauw is operated by KNMI; it is located in the western part of the Netherlands and it is0.7m below sea-level. Surface elevation changes by no more than a few metres over 20km. The surrounding region is mainly agricultural.
Measurements made using the following remote sensing systems at Cabauw have contributed to Cloudnet:
• 35 GHz cloud radar (KNMI)
• 3.3 GHz FMCW radar (TARA) (TUD) • 905 nm lidar ceilometer (CT75K) (KNMI)
• 22 channel wave radiometer (MICCY) (UBonn)
• Total Sky Imager (TSI-440) (KNMI)
Additional observations made within 100km of Cabauw with:
• Ceilometers (CT12K, LD-40)• Sky infrared temperature
Cesar
CRS - CHILBOLTON
Cloudnet Final Symposium – 12 October 2005
View of the cloud radars and lidars with the 25m antenna behind
Chilbolton is operated by CCLRC-RAL; it is located in Southern England and itis 84m above sea-level.Surface elevation changes by 240m over20km. The surrounding region is mainly agricultural downland with some wooded and residential areas.
Measurements made using the followingremote sensing systems at Chilbolton have contributed to Cloudnet:
• 35 GHz cloud radar (Copernicus)• 94 GHz cloud radar (Galileo)• 905 nm lidar ceilometer (CT75K)• 3 channel wave radiometer
Additional observations made atChilbolton with:
• 355 nm Raman lidar• 3 GHz radar (CAMRa)• Visible sky camera
CF A RR
CRS - SIRTA
Cloudnet Final Symposium – 12 October 2005
SIRTA remote sensing site at Palaiseau
Palaiseau is operated by IPSL; it islocated in a suburban community on a plateau 20km south of Paris, and it is ~160m above sea-level. The plateau is semi-urban divided equally between agricultural fields, wooded and housing/industrial areas
Measurements made using the following remote sensing systems at SIRTA have contributed to Cloudnet:
• 95 GHz cloud radar (RASTA)• 1064/532 nm polarimetric lidar• Ceilometer (LD-40)• 2 channel wave radiometer
(DRAKKAR)
Additional observations made atSIRTA with:
• Surface flux station (pyrheliometer/ pyranometer/pyrgeometer)• Sun-photometer• Radiosonde launches• Sonic anemometers (10 + 30 m)
Data from additional CRS-stations
Cloudnet Final Symposium – 12 October 2005
Distribution of DOE-ARM sites providing data to Cloudnet
Cloudnet processing algorithmshave been applied to data sets collected at additional sites.
These include: DWD-Lindenberg (Germany) ARM-SGP (Oklahoma) ARM-TWP (Manus) ARM-TWP (Nauru) ARM-NSA (Barrow)
All of the additional sites contain a 35 GHz cloud radar, a ceilometer and a multi-frequency microwave radiometer.
Cloudnet achievements
Cloudnet Final Symposium – 12 October 2005
Meeting objectives set at the beginning of the Cloudnet project:
• Operate the stations for a minimum of one week per month for two years
Achievements:• Operations at all sites started in October 2002 • Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:
Cloud radars / Backscatter lidars / Microwave radiometers
Radar Data for Cloudnet
Cloudnet Final Symposium – 12 October 2005
Instrument [Location]
Type Range Resolution
Type of operation
Data collected
34.86 GHz
[Cabauw]
Coded-Pulse
Doppler
Co-Pol +’X-Pol’
0.2 – 13 km
adjustable
90 m
adjustableContinuous 8/2001 - 6/2005
TARA
3.3 GHz
[Cabauw]
FM-CW
Doppler
Dual-Pol
15 km 30 mContinuous 10/2001 -
9/2005
GALILEO
94.0 GHz
[Chilbolton]
Pulsed
Doppler
Co-Pol
16 km 60 mContinuous
8/2001 - 3/2002
4/2003 - 4/2004
COPERNICUS
34.96 GHz
[Chilbolton]
Coded-Pulse
Doppler
Dual-Pol
15 km
adjustable
30 m
adjustableContinuous
4/2004 - 10/2004
12/2004 - 9/2005
RASTA
95.0 GHz
[SIRTA]
Pulsed
Doppler
Co-Pol
15 km 60 m Mon-Fri
(8:00-20:00)
------------
Continuous
10/2002-9/2003
-------------------
10/2003-9/2004
Lidar data for Cloudnet
Cloudnet Final Symposium – 12 October 2005
Instrument
[Location]
Type Range Resolution
Type of
operation
Data collected
CT75K 905 nm
[Cabauw]Ceilometer
11 km 30 m Continuous9/2001-9/2005
CT75K
905 nm
[Chilbolton]
Ceilometer11 km 30 m Continuous
9/2001-9/2005
LNA
1064/532 nm
[SIRTA]
Pulsed
Co-Pol+X-Pol
15 km 15 m Mon – Fri
(8:00 – 20:00)
[Not in rain]
10/2002-9/2005
LD-40
[SIRTA]Ceilometer
6 km 30 Continuous01/2003-10/2004
wave radiometer data for Cloudnet
Cloudnet Final Symposium – 12 October 2005
Instrument
[Location]
Channel Frequencies
Channel BTmp resolution
Type of operation
Data
collected
MICCY
[Cabauw]
[22 channels]22.235 - 28.235 GHz
50.8 - 58.8 GHz
90.0 GHz~0.1 K
Continuous 8/2001 – 8/2003
CMR
[Chilbolton]
22.2 GHz
28.8 GHz
37.6 Ghz
0.4 K Continuous 4/2003 - 9/2005
DRAKKAR
[SIRTA]
23.5 GHz
36.5 GHz 0.25 K Continuous 7/2002 - 9/2005
Cloudnet achievements
Cloudnet Final Symposium – 12 October 2005
Meeting objectives set at the beginning of the Cloudnet project:
• Operate the stations for a minimum of one week per month for two years
Achievements:• Operations started in October 2002 – see data summary tables• Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:
Cloud radars / Backscatter lidars / Microwave radiometers
• Successful cross-calibration of the three cloud radars was achieved by RASTA being operated at Chilbolton and Cabauw
Cloudnet achievements
Cloudnet Final Symposium – 12 October 2005
Meeting objectives set at the beginning of the Cloudnet project:
• Operate the stations for a minimum of one week per month for two years
Achievements:• Operations started in October 2002 – see data summary tables• Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:
Cloud radars / Backscatter lidars / Microwave radiometers• Successful cross-calibration of the three cloud radars was achieved
by RASTA being operated at Chilbolton and Cabauw
• Investigated the lifetime and reliability of the cloud radar amplifiers
Experiences with 94 GHz Cloud Radar amplifiers
Cloudnet Final Symposium – 12 October 2005
The Extended Interaction Klystron Amplifier (EIKA) in the 94 GHz GALILEO radar at Chilbolton operated for 3 years losing 20dB of Tx power before it failed in March 2002.
Plot of Z measured using GALILEO in rain illustrates how the power declined with time
A replacement EIKA for GALILEO was acquired in April 2003 – it ran for 12 months continuously before it lost 10dBof Tx power. This is in line with similarlosses experienced by the EIKA in RASTA
Design modifications to the cathode and its operating temperature are being implemented by the manufacturer
Experiences with 35 GHz Cloud Radar amplifiers
Cloudnet Final Symposium – 12 October 2005
The output power of the 35 GHz travelling wave tube (TWT) that is used in the cloud radar at Cabauw has gradually decreased with time. In August 2001 the output power was approximately 90 W, it had decreased to 20 W by the end of 2004. This was more than expected for a TWT operated continuously for 4 years.
The output power from the 35GHz EIKA used in theCOPERNICUS radar at Chilbolton has remained high after 22 months of operation. There has been a 1.5dB fall in gain after 16,000 hours. Can cope withanother ~12dB loss in gain
Cloudnet achievements
Cloudnet Final Symposium – 12 October 2005
Meeting objectives set at the beginning of the Cloudnet project:
• Operate the stations for a minimum of one week per month for two years
Achievements:• Operations started in October 2002• Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:
Cloud radars / Backscatter lidars / Microwave radiometers• Successful cross-calibration of the three cloud radars was achieved
by RASTA being operated at Chilbolton and Cabauw• Investigated the lifetime and reliability of the 94GHz radar amplifier
• Development of new techniques for auto-calibration of cloud radarsand cloud lidars – subject of next talk (Ewan O’Connor)
Cloudnet achievements (cont)
Cloudnet Final Symposium – 12 October 2005
• Archived the model forecast data over each of the sites• Data from seven operational forecast models were archived at the University of Reading for each of the CRS stations
• Measurements – data handling• Processed data collected during the project has been archived at the University of Reading
• Objective categorisation of radar and lidar targets – subject of later talk (Robin
Hogan)
• Development of a technique to improve estimation of LWP from wave radiometers by use of ceilometer data