SPACE WEATHER

For solar wind dials without any explanatory text, see this page. It also has a few dials that are not shown here. A web page with more explanatory text is also available.

Current Space Weather Status

This "stoplight" shows the more severe of the following three gauges of space weather:

Most Recent K_P Index:: Condition GREEN

This index is based on the most recent USAF/NOAA estimated planetary geomagnetic activity (K_P) 1-hour index. Our index is determined as follows:
Condition Estimated (1-Hour) K_P

Green 0 <= K_P < 4

Yellow 4 <= K_P < 7

Red K_P => 7
Solar Wind Observations: Condition GREEN

This index is keyed to the estimated instantaneous asymptotic voltage across the polar cap, the single most important measure of electrical power delivered to the atmosphere from the solar wind. We now use data from the ACE Real-Time Solar Wind package since this spacecraft is tracked more often than WIND. (The old estimate was based on observations from NASA's WIND spacecraft. An updated graph of that estimate is still available.) The index is determined as follows:
Condition Polar Cap Potential (PCP) Range

Green 0 kV <= PCP < 100 kV

Yellow 100 kV <= PCP < 200 kV

Red PCP >= 200 kV

Note: Yellow-to-Green transitions will now occur at 90 kV, and Red-to-Yellow transitions will occur at 190 kV. This should reduce condition changes caused by small fluctuations near the thresholds.
NOAA/SEC Forecast: Condition YELLOW

This index is based on the forecasted geomagnetic event probabilities over the next two days (section VI of the NOAA/SEC Forecast) as follows:
Condition Next Day Probabilites (P₁) Second Day Probabilities (P₂)

Green P₁ <= 35% P₂ <= 35%

Yellow 35% < P₁ <= 50% P₂ > 35%

Red P₁ > 50% Not Applicable

Condition	Estimated (1-Hour) K_P
Green	0 <= K_P < 4
Yellow	4 <= K_P < 7
Red	K_P => 7

Condition	Polar Cap Potential (PCP) Range
Green	0 kV <= PCP < 100 kV
Yellow	100 kV <= PCP < 200 kV
Red	PCP >= 200 kV

Condition	Next Day Probabilites (P₁)	Second Day Probabilities (P₂)
Green	P₁ <= 35%	P₂ <= 35%
Yellow	35% < P₁ <= 50%	P₂ > 35%
Red	P₁ > 50%	Not Applicable

Latest Observations from the ACE spacecraft

Last Measurement (at Sun-Earth L1 Point): May 14, 2001 8:44 UT

Sun-Earth L1 Point is approximately 45 minutes upwind of the Earth.

Solar Wind

Interplanetary Magnetic Field

Link to Recent History of Solar Wind Parameters

Magnetospheric Response: Voltage Across the Polar Cap

You can now receive e-mail notification whenever the stoplight sets to red! (Actually, you can be notified whenever any of these conditions change.) Just send e-mail to listserv@listserv.rice.edu with the following in the body of the message:
SUBSCRIBE SPACALRT first_name last_name
For "Joe User" to subscribe, this would be:
SUBSCRIBE SPACALRT Joe User

Stoplight state changes are now logged. There are three logs, one for each condition index (K_P,Solar Wind,and NOAA/SEC.) The earliest logged transition occurred on January 23, 1999.

More about the solar wind's recent behavior can be found on my Current Solar Wind Conditions page.
Also, here's an index to Space Weather Resources. Other items of interest include NOAA/SEC Current Conditions, my composite current Auroral Images page, Windows on the Universe: Space Weather, and Public Outreach Index, Department of Space Physics and Astronomy, Rice University.

This page has been accessed

times since March 22, 1996.

Please accept my apologies for the recent inavailability of this page. The web server was taken down for an upgrade in late March 2000, and my account was locked out in the process. It took until April 7, 2000 for me to regain access.

Andrew L. Urquhart

(urquhart@rice.edu)

Department of Space Physics & Astronomy
Rice University

Static information was last revised on 4/7/2000.