Transcript CloudNet Observing Stations

Cloudnet Observing
Stations
Instrumentation
C L Wrench
Cloudnet Final Symposium – 12 October 2005
Cloud Remote Sensing Stations
Cloudnet started with three cloud
observing 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.
Cloudnet Final Symposium – 12 October 2005
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
• 35 GHz cloud radar
(KNMI)
within 100km of Cabauw with:
• 3.3 GHz FMCW radar (TARA)
(TUD)
• 905 nm lidar ceilometer (CT75K)
(KNMI)
• Ceilometers (CT12K, LD-40)
• 22 channel mwave radiometer (MICCY) (UBonn) • Sky infrared temperature
• Total Sky Imager (TSI-440)
(KNMI)
Cloudnet Final Symposium – 12 October 2005
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.
C
FAR
R
Measurements made using the following
remote 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 mwave radiometer
Cloudnet Final Symposium – 12 October 2005
Additional observations made at
Chilbolton with:
• 355 nm Raman lidar
• 3 GHz radar (CAMRa)
• Visible sky camera
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:
• 95 GHz cloud radar (RASTA)
• 1064/532 nm polarimetric lidar
• Ceilometer (LD-40)
• 2 channel mwave radiometer
(DRAKKAR)
Cloudnet Final Symposium – 12 October 2005
Additional observations made at
SIRTA with:
• Surface flux station (pyrheliometer/
pyranometer/pyrgeometer)
• Sun-photometer
• Radiosonde launches
• Sonic anemometers (10 + 30 m)
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
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
Radar Data for Cloudnet
Instrument
[Location]
Type
Range
Resolution
34.86 GHz
[Cabauw]
Coded-Pulse
Doppler
Co-Pol +’X-Pol’
0.2 – 13 km
adjustable
90 m
adjustable
TARA
3.3 GHz
[Cabauw]
FM-CW
Doppler
Dual-Pol
15 km
30 m
GALILEO
94.0 GHz
[Chilbolton]
Pulsed
Doppler
Co-Pol
16 km
COPERNICUS
34.96 GHz
[Chilbolton]
Coded-Pulse
Doppler
Dual-Pol
15 km
adjustable
30 m
adjustable
RASTA
95.0 GHz
[SIRTA]
Pulsed
Doppler
Co-Pol
15 km
60 m
Type of
operation
Data
collected
Continuous
8/2001 - 6/2005
Continuous
10/2001 - 9/2005
8/2001 - 3/2002
60 m
Continuous
4/2003 - 4/2004
Cloudnet Final Symposium – 12 October 2005
4/2004 - 10/2004
Continuous
12/2004 - 9/2005
Mon-Fri
(8:00-20:00)
-----------Continuous
10/2002-9/2003
------------------10/2003-9/2004
Lidar data for Cloudnet
Instrument
[Location]
CT75K
905 nm
[Cabauw]
CT75K
905 nm
[Chilbolton]
LNA
1064/532 nm
[SIRTA]
Type
Range
Resolution
Type of
operation
11 km
30 m
Continuous
9/2001-9/2005
Ceilometer
11 km
30 m
Continuous
9/2001-9/2005
Ceilometer
Pulsed
15 km
15 m
Co-Pol+X-Pol
LD-40
Data
collected
6 km
Ceilometer
[SIRTA]
Cloudnet Final Symposium – 12 October 2005
30
Mon – Fri
(8:00 – 20:00)
[Not in rain]
10/2002-9/2005
Continuous
01/2003-10/2004
mwave radiometer data for Cloudnet
Instrument
[Location]
Channel
Frequencies
MICCY
[22 channels]
[Cabauw]
22.235 - 28.235 GHz
50.8 - 58.8 GHz
90.0 GHz
~0.1 K
22.2 GHz
28.8 GHz
37.6 Ghz
CMR
[Chilbolton]
DRAKKAR
Channel
Type of
operation
Data
collected
Continuous
8/2001 – 8/2003
0.4 K
Continuous
4/2003 - 9/2005
0.25 K
Continuous
7/2002 - 9/2005
BTmp resolution
23.5 GHz
36.5 GHz
[SIRTA]
Cloudnet Final Symposium – 12 October 2005
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
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
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
Cloudnet Final Symposium – 12 October 2005
Design modifications to the cathode and
its operating temperature are being
implemented by the manufacturer
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
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 O’Connor)
Cloudnet Final Symposium – 12 October 2005
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