Cloudnet Observing Stations

1
Cloudnet Observing Stations

• Instrumentation
• C L Wrench

Cloudnet Final Symposium 12 October 2005
2
Cloud Remote Sensing Stations

• Cloudnet started with three cloud
• observing stations
• Cabauw, The Netherlands
• 51.971N, 4.927E
• Chilbolton, United Kingdom
• 51.145N, 1.437W
• 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.
Cloudnet Final Symposium 12 October 2005
3
CRS - CABAUW
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 is 0.7m
below sea-level. Surface elevation changes by no
more than a few metres over 20km. The
surrounding region is mainly agricultural.
Cesar
Measurements made using the following remote
sensing systems at Cabauw have contributed to
Cloudnet
Additional observations made within 100km of
Cabauw with

• 35 GHz cloud radar
  (KNMI)
• 3.3 GHz FMCW radar (TARA) (TUD)
• 905 nm lidar ceilometer (CT75K) (KNMI)
• 22 channel mwave radiometer (MICCY) (UBonn)
• Total Sky Imager (TSI-440) (KNMI)

• Ceilometers (CT12K, LD-40)
• Sky infrared temperature

Cloudnet Final Symposium 12 October 2005
4
CRS - CHILBOLTON
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 it is 84m above
sea-level. Surface elevation changes by 240m
over 20km. The surrounding region is mainly
agricultural downland with some wooded and
residential areas.
Measurements made using the following remote
sensing systems at Chilbolton have contributed
to Cloudnet
Additional observations made at Chilbolton with

• 35 GHz cloud radar (Copernicus)
• 94 GHz cloud radar (Galileo)
• 905 nm lidar ceilometer (CT75K)
• 3 channel mwave radiometer

• 355 nm Raman lidar
• 3 GHz radar (CAMRa)
• Visible sky camera

Cloudnet Final Symposium 12 October 2005
5
CRS - SIRTA
SIRTA remote sensing site at Palaiseau
Palaiseau is operated by IPSL it is located 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
Additional observations made at SIRTA with

• 95 GHz cloud radar (RASTA)
• 1064/532 nm polarimetric lidar
• Ceilometer (LD-40)
• 2 channel mwave radiometer
• (DRAKKAR)

• Surface flux station (pyrheliometer/
• pyranometer/pyrgeometer)
• Sun-photometer
• Radiosonde launches
• Sonic anemometers (10 30 m)

Cloudnet Final Symposium 12 October 2005
6
Data from additional CRS-stations
Distribution of DOE-ARM sites providing data to
Cloudnet
Cloudnet processing algorithms have 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 Final Symposium 12 October 2005
7
Cloudnet achievements

• 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

Cloudnet Final Symposium 12 October 2005
8
Radar Data for Cloudnet
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 adjustable Continuous 8/2001 - 6/2005
TARA 3.3 GHz Cabauw FM-CW Doppler Dual-Pol 15 km 30 m Continuous 10/2001 - 9/2005
GALILEO 94.0 GHz Chilbolton Pulsed Doppler Co-Pol 16 km 60 m Continuous 8/2001 - 3/2002 4/2003 - 4/2004
COPERNICUS 34.96 GHz Chilbolton Coded-Pulse Doppler Dual-Pol 15 km adjustable 30 m adjustable Continuous 4/2004 - 10/2004 12/2004 - 9/2005
RASTA 95.0 GHz SIRTA Pulsed Doppler Co-Pol 15 km 60 m Mon-Fri (800-2000) ------------ Continuous 10/2002-9/2003 ------------------- 10/2003-9/2004
Cloudnet Final Symposium 12 October 2005
9
Lidar data for Cloudnet
Instrument Location Type Range Resolution Type of operation Data collected
CT75K 905 nm Cabauw Ceilometer 11 km 30 m Continuous 9/2001-9/2005
CT75K 905 nm Chilbolton Ceilometer 11 km 30 m Continuous 9/2001-9/2005
LNA 1064/532 nm SIRTA Pulsed Co-PolX-Pol 15 km 15 m Mon Fri (800 2000) Not in rain 10/2002-9/2005
LD-40 SIRTA Ceilometer 6 km 30 Continuous 01/2003-10/2004
Cloudnet Final Symposium 12 October 2005
10
mwave radiometer data for
Cloudnet
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 Final Symposium 12 October 2005
11
Cloudnet achievements

• 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 Final Symposium 12 October 2005
12
Cloudnet achievements

• 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

Cloudnet Final Symposium 12 October 2005
13
Experiences with 94 GHz Cloud
Radar amplifiers
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 10dB of Tx power. This is in
line with similar losses experienced by the EIKA
in RASTA Design modifications to the cathode and
its operating temperature are being implemented
by the manufacturer
Cloudnet Final Symposium 12 October 2005
14
Experiences with 35 GHz Cloud
Radar amplifiers
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
the COPERNICUS 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 with another 12dB loss in gain
Cloudnet Final Symposium 12 October 2005
15
Cloudnet achievements

• 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 radars
• and cloud lidars subject of next talk (Ewan
  OConnor)

Cloudnet Final Symposium 12 October 2005
16
Cloudnet achievements (cont)

• 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
• mwave radiometers by use of ceilometer
  data

• 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

Cloudnet Final Symposium 12 October 2005