What does KPI mean to me?
When we are looking at the data, you will often hear Aurora chasers talking about the KPI level. We need to factor in more than just the KPI, such as the density, bz, etc. With that being said, there is a map attached that shows where you should be for each KPI.
I cannot stress enough that this map is not perfect. There can be aurora with KPI 2 and great supporting data. There can also be no Aurora at KPI 5 and poor supporting data.
Personally I am located in Brandon. If I see KPI 4 with good supporting data, that will get me out of the house and heading north. In hopes of seeing a green glow along the horizon. If I see KPI 5 I will be on my way out of the city and to a good North facing viewpoint. In hopes of a great show. If I see anything above KPI 6, that is when my excitement goes through the roof.
Where do I need to go to see the aurora?
I will always recommend for people to get out of the city limits. Cities are very bright, and they will drown out the aurora. With that being said, if the aurora is strong enough it can be seen from the city. There have been instances when the Aurora was seen in the middle of Winnipeg! Now just imagine how bright the Aurora would have been if you were out of town.
The picture above shows a dark sky map of Manitoba. I like to get out of the green/red areas, and into the blue or white areas. Click on the image to see how bright your area is!
When I am out chasing the aurora, I like to have the city lights to the south of me. Then dark skies to the north. I like to go north of Forrest, which is far enough from Brandon to see/photograph the aurora for yourself.
To view this map yourself, click on this photo.
Data Breakdown
The KP Index
Hemispheric Power
Hemispheric Power
The KP Index (KPI) is determined by the strongest geomagnetic activity in a set 3 hour window across the globe. KPI is a good determining factor for how low the Aurora will be. In Southern Manitoba, we are looking for KPI 4 or better.
The windows the KPI are calculated in are 18h-21h, 21h-00h, 00h-03h and so on. These times are often in UTC, to convert this to Manitoba time simply subtract 6 hours. Manitoba is 6 hours behind UTC (5 hours during Daylight savings time).
The reason we do not want to rely simply on KPI is If we reach KPI 7 at 21:30h, it will show that KPI level until it resets at 00h (unless we reach KPI 8 of course). This means you can be out 2 hours after KPI 7 was reached, and it may only be KPI 3. That is why it is critical you learn how to read the other data.
Hemispheric Power
Hemispheric Power
Hemispheric Power
The hemispheric power is the amount of charged particles impacting the Earth at a time. It is split into Northern and Southern hemisphere.
When we are out chasing we want more than 40GW. The more the better. If you see this number get above 50GW, it is time to get excited. Especially when it lasts for a long period of time.
Solar wind
Hemispheric Power
Interplanetary Magnetic Field (Bz)
When we are getting ready to go out chasing, we want to watch the Solar wind quite closely. Enhanced Solar wind is caused by events on the sun. Our baseline of Solar wind is ~200km/sec. To get my camera gear ready, I like to see 500km/sec at least.
With Solar wind, the higher the better.
This solar wind is calculated by the DSCOVR satellite, which sits at the L1 point between the Earth and Sun. L1 is a location where the gravity from the Earth and Sun equal the same. This means the satellite gives us 24 hours worth of data each day.
On Spaceweather Live you will see a note that gives you a time for how long it will take for the current solar wind to reach Earth from DSCOVR.
Interplanetary Magnetic Field (Bz)
Interplanetary Magnetic Field (Bz)
Interplanetary Magnetic Field (Bz)
Bz is the one thing you need to learn to read if you want to chase the aurora. I like to refer to the Bz as Earth's shields.
Earth's atmosphere reacts more to a negative Bz. When the Sun ejects Charged particles it is either a positive or negative charge. For an aurora display we want a negative charge. The longer it has been negative the better. And the further South (negative) the better. If the Bz is negative for a prolonged amount of time, it won't take much Solar wind to produce a great show.
Interplanetary Magnetic field (Bt)
Interplanetary Magnetic Field (Bz)
Interplanetary Magnetic field (Bt)
The Bt refers to the combined measure of the magnetic field strength.
We want a higher value as an Aurora chaser. It is considered a moderate storm when the Bt is above 10nT. 20nT is considered a strong storm. Then 30nT is considered a very strong storm.
If this value is very low (<5nT) it can destroy the rest of the Solar data. Killing any chance we have to view the Aurora.
Solar Density
Interplanetary Magnetic Field (Bz)
Interplanetary Magnetic field (Bt)
The density refers to how many charged particles are being carried by the Solar Wind. Density above 30p/cm³ is considered very dense.
When you are watching the Solar Density, you want a higher number. The higher the better.
Moon Phase
Spaceweather live
Spaceweather live
When we are looking up at the night sky we need to pay attention to the moon phase. The moon is illuminated by the Sun, and in turn is very bright. A full moon is so bright that it will cast a shadow!
A bright moon will drown out the aurora, however it can also work well to light up your foreground. There is a balance between the moon and aurora.
A full moon will not prevent me from chasing the aurora. I just pay closer attention to the solar data and will only go out if the data is very strong. For the best show, it is best to go chasing around the new moon.
Spaceweather live
Spaceweather live
Spaceweather live
The following screenshots are all taken from Spaceweather Live. Follow the link below which will take you to their website, to see the current aurora data for yourself.