|
|
Introduction
This Website is a gateway for space weather displays
based upon cosmic ray data returned by the Spaceship Earth
network of neutron monitors. In the future it will also include
space weather displays based upon data from the worldwide network
of muon detectors.
The top of the site contains reduced versions of the plots
that we consider most relevant for space weather prediction.
Click any plot to obtain an enlarged version. As our
space weather products are improved and optimized, these plots
will change from time to time.
Below is a brief description of the multi-national team providing
data for this site. Following that is a listing of available
realtime space weather displays based upon cosmic ray data, including
a link to the display, a brief discussion of its use for space weather
forecasting or specification.
Disclaimer
This is a prototype, experimental site.
Use of material on this site for any purpose
is at your own risk. We do not guarantee that the realtime displays
will be available or up-to-date at all times. Realtime data have not been
subjected to rigorous quality control; it may contain "glitches" that
produce false alarms or fail to detect true space weather disturbances.
Even when the data are good, there may be physical factors that produce
false alarms or fail to detect true space weather disturbances.
Participating Institutions
Spaceship Earth
Spaceship Earth is an 11-station network of neutron monitors strategically located
to provide precise, real-time, 3-dimensional measurements of the cosmic ray
angular distribution. Participating institutions include the
University of Delaware,
IZMIRAN,
Polar Geophysical Institute (Apatity),
Institute of Solar-Terrestrial Physics (Norilsk),
Institute of Cosmophysical Research and Aeronomy (Tixie Bay).
Institute of Cosmophysical Research and Radio Wave Propagation (Cape Schmidt),
Australian Antarctic Division (Mawson),
and the University of Tasmania.
For additional information on Spaceship Earth, neutron monitors,
and space weather, please visit the home page of the
University of Delaware
Bartol Research Institute neutron monitor program
The Muon Team
In the future this site will include space weather products from
a growing muon detector network. Participating institutions include the
University of Delaware,
Shinshu University (Japan),
Nagoya University (Japan),
Southern Space Observatory of INPE (Brazil),
University of Santa Maria (Brazil),
Australian Antarctic Division,
and the University of Tasmania.
Links to Space Weather Displays (with Brief Explanations)
Important Note: This plot is an experimental prototype. The display format
may change as a result of ongoing research to optimize space weather
prediction with cosmic rays.
Refer here for a brief explanation of the current display format.
DISPLAY FORMAT
Top Panel: ACE magnetic field magnitude |B| (green), north-south component
Bz (pink-red) in GSE coordinates, and 1-hour estimated Kp index (blue).
Second Panel:Cosmic ray density determined by fitting a first-order anisotropy to available
Spaceship Earth stations.
Third Panel (Loss Cone Display): Each circle represents an hourly
average of the cosmic ray intensity measured by a single Spaceship Earth
station relative to the cosmic ray density. Red circles indicate deficit intensity,
blue circles indicate excess intensity, and the size of the circle scales with
the magnitude of the deficit or excess; see right side of plot for scale.
Horizontal axis is time (3 days total displayed), and vertical axis is
station pitch angle. Station pitch angle is the angle between the station viewing
direction (median rigidity particle) and the Sunward magnetic field direction (ACE
1-h average). Here "Sunward" is defined relative to a nominal 45 degree sprial
field; a station with zero degree pitch angle views particles coming from
the Sun along the magnetic field. Stations were
inter-normalized by means of a 24-h trailing moving average.
Fourth Panel (Bidirectional Streaming Display):Residual deviation
after subtracting the fitted first-order anisotropy from each station. Red and blue
now represent deficit and excess relative to a first-order anisotropy. This
plot is thus a display of higher order anisotropies in the cosmic ray pitch
angle distribution.
USE OF THIS PLOT
Loss Cone Display (third panel): This plot will sometimes display
a cosmic ray loss cone precursor ahead of an approaching CME shock.
The defining characteristic of a loss cone precursor
is a strong suppression of cosmic ray intensity for particles
arriving from the Sunward magnetic field direction. Thus, look for large
red circles concentrated near small pitch angles. The physical mechanism
behind loss cones is that these particles trace to the region downstream of
the shock, where cosmic ray intensity is generally suppressed (Forbush decrease).
In major storms, loss cones are often observed about 4 h in advance of shock
arrival, and may be observed 24 h in advance in rare cases. Depending
upon shock-field geometry, however, loss cones can be difficult
to detect, or absent entirely.
Bidirectional Streaming Display (fourth panel):This plot can be
used to indicate when Earth is within a large interplanetary CME.
Cosmic rays within a large CME often exhibit bidirectional streaming,
in a manner similar to the bidirectional electrons observed at much lower energy.
Intensity is suppressed near 90 degree pitch angles, and elevated near 0 and
180 degrees. Thus, look for red circles concentrated near 90 degrees,
with blue circles on both sides.
Important Note: This is a plot of nearly raw realtime data,
recommended for use only by those familiar with interpretation
of neutron monitor data. A display format more useful for nonspecialists
is under development.
DISPLAY FORMAT
Pressure corrected 1-minute data from several Spaceship Earth
stations and a few other high-latitude stations are displayed.
USE OF THIS PLOT
This plot can be used as an early warning of a large solar energetic
particle event. Look for a smooth rise at one or more stations (preferably more)
occuring over a period of 15 minutes or more, followed by a (usually) slower
decay. Generally these displays will be of interest only during cosmic
ray ground level enhancements (GLE) or major Forbush decreases.
Most of the time the displayed variations are simply statistical noise.
Isolated spikes are probably data glitches and should be ignored
if unconfirmed by other stations.
Important Note: This plot is an experimental prototype. The display format
may change at any time.
Refer here for a brief explanation of the current display format.
DISPLAY FORMAT
Top Panel: ACE magnetic field magnitude |B| (green), north-south component
Bz (pink-red) in GSE coordinates, and 1-hour estimated Kp index (blue).
Second Panel:Cosmic ray density determined by fitting a first-order anisotropy to available
Spaceship Earth stations.
Third Panel:Cosmic ray flow direction projected into ecliptic plane, as determined
by fitting a first-order anisotropy to Spaceship Earth data. The GSE X-axis points
toward the Sun (upward in the plot), and the Y-axis points opposite the direction of Earth's revolution
about the Sun (leftward in the plot). Each red line segment represents an hourly measurement of the
anisotropy, with the base plotted at the time of measurement, and the head oriented according
to the direction and magnitude of the anisotropy. We follow the meteorological convention,
i.e., arrows point in the direction that the flow is coming from.
Fourth Panel:Cosmic ray flow direction projected into a plane oriented normal
to the Earth-Sun line, as determined
by fitting a first-order anisotropy to Spaceship Earth data. The GSE Z-axis points
northward of the ecliptic plane (upward in the plot),
and the Y-axis points opposite the direction of Earth's revolution
about the Sun (leftward in the plot). Each red line segment represents an hourly measurement of the
anisotropy, with the base plotted at the time of measurement, and the head oriented according
to the direction and magnitude of the anisotropy. We follow the meteorological convention,
i.e., arrows point in the direction that the flow is coming from.
USE OF THIS PLOT
This plot specifies current conditions in the nearby interplanetary medium.
It simply tells which way the (cosmic ray) wind blows and how strongly.
This plot displays neutron rates at individual stations. It should be
self-explanatory. Only McMurdo is
displayed above, but clicking the link will transfer to a page where six stations
(South Pole, McMurdo, Thule, Inuvik, Fort Smith, and Newark) are displayed
in a similar format.
Other Cosmic Ray Displays (not realtime)
- Solar Modulation Plot.
Pressure-corrected McMurdo neutron rate (27-day means) along with monthly sunspot
number from 1960 to the present. Typically updated monthly.
- Six-Month Plot.
Pressure-corrected count rates for the past 6 months at multiple (~15) stations, along with
Kp and Dst. Typically updated daily. (Note: SPoleN is a standard 3NM64 at South Pole,
while SPoleB is our "Polar Bare," a 3NM64 without the usual lead shielding.)
It responds to a slightly lower energy primary cosmic ray than the standard monitor.
- Multi-Year Plot.
Pressure-corrected count rates from 2000 September 8 to the present for multiple (~8)
stations, along with Kp and Dst.
Depending upon your browser settings, you may need to expand the image and scroll
to view the entire plot.
(Note: SPoleN is a standard 3NM64 at South Pole,
while SPoleB is our "Polar Bare," a 3NM64 without the usual lead shielding.
It responds to a slightly lower energy primary cosmic ray than the standard monitor.)
- Longer Multi-Year Plot.
Similar to previous, but goes back to 1998 for some stations.
|
