Incoherent Scatter Radar Station operated by SRI and DMI

1
Kangerlussuaq ISR Research Facility
Incoherent Scatter Radar Station operated by SRI
and DMI
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)
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 Qaa-naaq
(Thule). More recently these stations have been
upgrades to use modern Digisondes. The
ionosondes/ digisondes measures the electron
content in the upper atmo-sphere, 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.
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.
Sondrestrom Research Facility at Kangerlussuaq
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.
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.
LIDAR beam in the polar night with auroral
activity (Photo by C. Heinselman)
Lidar beam on a background of active aurora. The
ISR radar is seen to the right. (Photo by C.
Heinselman)
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.

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
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
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
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
geo-effectiveness 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.

• .

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/
Peter Stauning. Danish Meteorological Institute.
September 2002. pst_at_dmi.dk