Polar magnetic disturbance, farside eruptions and auroras

A disturbance is rippling through Earth’s polar magnetic field on March 1st. Bright auroras have been sighted in Sweden and Finland. Rob Stammes of the Polar Light Center in Lofoten reports about magnetometer needles start to swing. This magnetic storm came as a surprise. Starting just before 19.00 UTC,with a swinging magnetometer and larger ground currents. Some seconds before the magnetometer start to move and the induced ground current chanced, there was an aurora reflection on VHF radio installations.

Planetary K-index
Now: Kp= 4 unsettled
24-hr max: Kp= 4 unsettled

Interplanetary Mag. Field
B_total: 5.2 nT
B_z: 4.7 nT south 

Solar wind
speed: 481.9 km/sec
density: 2.0 protons/cm³

The Earthside of the sun is quiet, but the other side is not. On Feb. 29th, a farside Sunspot 1420 erupted multiple times, followed by another eruption around Sunspot 1422. Three CMEs hurled over the sun’s western limb. A pair of Coronal Mass Ejections are seen today in the latest STEREO Behind COR 2 images. This eruptions were farsided so they will not be Earth directed. The Solar and Heliospheric Observatory (SDO) recorded the expanding clouds:

While the odds of more farside eruptions today seem high, here on “our side” everything seems quiet.  Sunspot 1423 poses no threat for strong flares. SWPC/NOAA forecasters say the chances of M- and X-class solar flares are no more than 1%. The geomagnetic field is expected to be quiet for today (March 01). A slight increase to quiet to unsettled levels is expected tomorrow (March 02) due to a small coronal hole. A solar wind stream flowing from this minor coronal hole could reach Earth on March 4-5.

The solar wind has shown a gradual increase to near 550km/s today and combined with a predominantly south tilting Bz, could help trigger Aurora at very high latitudes. Meanwhile, take a look at these wonderful images of auroras that occurred for last two days.

 Featured image credit: Kaj Hoglund