Transcript H8-Isr-str

Kangerlussuaq ISR Research Facility
Incoherent Scatter Radar Station operated by SRI and DMI
Ionosonde – Digisonde Observations at DMI
Exploration of the atmosphere by radio wave techniques
became a widely used tool from around 1950. At that time
the requirements to reliable long-distance HF radio
communication started international efforts to deploy a
worldwide net of ionospheric monitoring stations. The efforts
were coordinated through the International Scientific Radio
Union, URSI. Since 1951 DMI has operated an ionosonde
station in Qeqertarsuaq (Godhavn), since 1957 a station in
Narsarsuaq, and since 1966 an ionosonde station in Qaanaaq (Thule). More recently these stations have been
upgrades to use modern Digisondes. The ionosondes/
digisondes measures the electron content in the upper atmosphere, a parameter of great importance for the propagation
of radio waves. The altitude range is limited to exploring the
layers below the region of peak electron density.
Upper Atmospheric Research Facility in Kangerlussuaq
Just north of the Arctic Circle and 100 km inland from the west
coast of Greenland lies a research facility dedicated to studying
the polar upper atmosphere. For historical reasons, this research
station is known around the world as the Sondrestrom Upper
Atmospheric Research Facility in Kangerlussuaq, Greenland.
The facility is operated by SRI International, Menlo Park,
California, under the auspices of the U.S. National Science
Foundation and in joint cooperation with the Danish
Meteorological Institute. The facility has been operating in
Greenland since 1983 and continues to be in high demand by
the scientific communities. (Photo by C. Heinselman)
Incoherent Scatter Radar Observations
A major step for the exploration of the upper atmosphere
came with the construction of the Incoherent Scatter Radar
(ISR) instrument that uses backscattering from free electrons
rather than the specular reflections from electron layers
which is the basis fror ionosonde/digisonde operation. Hence
the ISR radar can observe electron densities beyond the
peak layer. In addition the instrument can measure drift
motions, temperatures and composition in the ionised part of
the upper atmosphere and turbulence and motions in the
neutral lower atmosphere.
Beacon - GPS – Lidar Observations
The range of observational tools have been further extended
by the use of satellite beacon radio signals for ionospheric
tomography (2-D mapping). Using signals from the GPS
satellites makes it possible to map the total ionospheric
electron contents (TEC) in the upper atmosphere between
the satellite and the receiver instrument. With Lidar
techniques another major step was taken to explore the
neutral atmospheric temperature profile and the aerosol
composition.
Lidar beam on a background
of active aurora. The ISR
radar is seen to the right.
(Photo by C. Heinselman)
Summary of Instrument Capabilities
The diagram below indicates the detection capabilities for a
range of instruments with respect to parameter as well as
altitude range. In this diagram the parameters are:
Tn
Neutral atmosphere temperature
[Nm]
Molecular atmospheric density
[Naer] Density of special constituents
[O3]
Ozone concentrations
Un
Drift motion of neutral atmosphere
[Ne]
Electron density
Te
Electron temperature
Tm
Molecular temperature
Vi
Drift motion of ionised atmosphere
.
Sondrestrom Research Facility at Kangerlussuaq
Instrumentation at ISR station
This facility is host to more than 20 instruments, the majority of
which provide unique and complementary information about
the arctic upper atmosphere. Together these instruments
advance our knowledge of upper atmospheric physics and
determine how the tenuous neutral gas interacts with the
charged space plasma environment. The suite of
instrumentation supports many disciplines of research; from
plate tectonics to auroral physics and space weather. The
facility instrumentation covers the electromagnetic spectrum
while the data results span the spectrum of polar research.
Incoherent Scatter Radar
The centerpiece instrument of the facility is an L-band
incoherent scatter (IS) radar with a 32 m fully steerable
antenna. The IS radar technique is a powerful tool capable of
measuring range-resolved ionospheric and atmospheric
parameters simultaneously from the ground to the outer
reaches of our atmosphere. Use of a steerable antenna allows
spatial coverage in both latitude and longitude.
Further Instruments
The facility hosts a wide range of additional optical and
radiowave instruments including:
Lidar (ARCLITE)
All-sky imager
Meridian imaging spectrometer
Multichannel photometer
UV spectrograph
Auroral photometer
Fabry-Pèrot interferometer
Michelson interferometer
UV spectrometer
Three-axis magnetometer
MF/HF receiver and imager
Meteor scatter radar
Search coil magnetometer
Three-frequency riometer
Imaging riometer
Digisonde
Satellite scintillation receiving systems
ELF/VLF receivers
Ozone spectrometers
Users of the ISR Observations
Data from the facility are used by hundreds of scientists annually.
Dozens of scientists, engineers, and students visit the site each
year to install hardware, implement collocated instruments, and
collect data in real time in multi-instrument campaigns.
DMI use of the ISR station
The ISR station conducts routine operation of various DMI
instruments to observe, e.g., Ozone, UV radiation, radio wave
absorption, and magnetic activity. In addition DMI is a frequent
user of the ISR radar, among other, for campaigns of combined
observations of atmospheric disturbances from ground and from
the Ørsted satellite. The DMI involvement in the sophisticated
observations from the ISR station was an essential motivation for
entering the Ørsted satellite project and has strengthened our
capabilities to deal with, among other, the GPS observations
from Ørsted.
Part of the text and some of the images are copied from SRI web site: http://isr.sri.com/
LIDAR beam in the polar night with auroral activity
(Photo by C. Heinselman)
The LIDAR system at the ISR Station
The ARCLITE System is located in the main building of the
Sondrestrom facility. The system presently consists of two
lidar systems: The Rayleigh/Mie lidar for middle
atmosphere studies of noctilucent clouds (NLCs), polar
stratospheric clouds (PSCs), temperatures, density and
gravity waves, and the sodium resonance lidar for
mesosphere / lower thermosphere studies of gravity waves
and the dynamics and chemistry of sporadic layer
formations. The Rayleigh/Mie lidar has been operating
since November of 1992. The sodium resonance lidar has
been operating since August of 1997. The LIDAR
instruments have provided core observations of Noctilucent
Clouds (NLC) for investigations of greenhouse gases like
illustrated below in a campaign logo:
NDSC, May 2002
The Network for Detection
of Stratospheric Change
(NDSC) has designated
the Rayleigh lidar as a
primary instrument in
their program.
ISR Observations in Space Weather Projects
The best opportunity to evaluate space weather geoeffectiveness is by combining the identification and
monitoring of space weather events by interplanetary
spacecraft with magnetosphere-ionosphere observations
by geospace and ground-based instruments. The
Sondrestrom Incoherent scatter radar operates on an alert
basis to capture the onset, main phase, and recovery
phase of coronal mass ejection (CME)-related
geomagnetic storms. Since 1997, the Sondrestrom radar
has been operated in the alert mode 18 times, totaling 430
hours of operation. Coordination with other radar facilities
has been established to measure global ionospheric
effects of CME-induced storms.
The ISR management office at SRI International is
prepared to assist with scheduling site operations and
crew, and to help providing access to and interpretation of
the data through a Space Weather Archive.
For DMI the availability of the ISR radar is an essential
asset for our planned Space Weather activities.
Peter Stauning. Danish Meteorological Institute. September 2002. [email protected]