Solar activity has fallen to the bottom of the next minimum of the 11-year solar cycle 1.5 years earlier than the schedule
The influence of the solar wind on the Earth (schematic image). The source is noaa.gov
Weak perturbations of the Earth’s magnetic field, sometimes reaching the level of a magnetic storm, are observed on our planet during the last days – approximately from the middle of Sunday. Most of this time, the magnetosphere is in a perturbed state, to which the value of the index Kp = 4 corresponds. Twice during this time, the amplitude of the field oscillations rose for a short time to Kp = 5, which corresponds to a weak storm, but the duration of these intervals was only 1-2 hours. In general, the occurring geomagnetic event is extremely weak.
None of the magnetic storms and none of the field disturbances observed in the last two months were related to solar activity. Thus, the cosmic weather in the vicinity of our planet is increasingly losing its connection with the Sun, which by all indications practically fell to the bottom of the next minimum of the 11-year solar cycle 1.5 years earlier than the schedule. Against this background, with the complete absence of even the weakest flares on the Sun, the main factor of cosmic weather was the solar wind – a plasma stream formed as a result of the continuous outflow of the upper layers of the solar atmosphere into the surrounding outer space. When the density or velocity of this stream changes, so does the pressure that it exerts on the earth’s magnetosphere – it is then amplified or weakened. The Earth’s field at the same time is out of balance and experiences fluctuations, which is observed as a storm. In this sense, the graph of magnetic storms now almost exactly reflects the graph of the change in the speed of the solar wind. This allows, even without looking at the data of spacecraft, from the very fact of the onset of magnetic disturbances, to conclude that the Earth has entered a faster stream of solar wind.
If you still look at the satellite data, then the speed of the solar wind blowing the Earth is now about 650 km / s and compared to the middle of yesterday increased by more than 50% – from 400 km / sec. Significantly increased now is the temperature of the wind – from 100 thousand degrees it has grown to almost half a million degrees. Strong oscillations of the interplanetary magnetic field are also observed, which further enhances the effect of wind on the magnetosphere of the Earth.
The observed disturbances should not last more than several hours, although certain fluctuations of the Earth’s field can be observed for about a day.
In general, we must understand that the effect of the solar wind on the Earth is very weak, and, in principle, can not cause strong magnetic storms. The main reason for really large disturbances affecting communications, spacecraft traffic and terrestrial electrical networks is only solar activity. Nevertheless, the Sun seems to finally release (or even already released) the Earth from its hands, so the main factor of space weather for the coming years will be the solar wind – at least until our star wakes up from sleep. A certain advantage of this situation, in addition to reducing the strength of magnetic storms, will be their better predictability. Unlike solar flares, the exact prediction of which has very low reliability, the solar wind speed is predicted much better and at much longer terms.
Courtesy of tesis.lebedev.ru