Changes of space weather and space climate at Earth orbit: An update

We present an update of the changes in space weather/space climate at Earth orbit using sunspot number (SSN) timeline (1700-2018), geomagnetic indices aa/Ap, solar polar magnetic field, interplanetary magnetic field (IMF) and galactic cosmic ray (GCR) flux in the stratosphere at high latitudes. The Cycle 24 is close to solar minimum, expected in 2020. The baseline of as index increases monotonically from 1900 to 1986 and declines steeply afterwards, solar polar magnetic field decreases systematically for the last three cycles (22-24) as do SSNs at cycle peaks. Livingston and Penn (2009) note a long term weakening of maximum magnetic field in sunspots since 1992. They expect SSNs for the Cycle 25 to peak at 7 (a steep decline in solar activity) leading to Maunder-like minimum, in contrast to prediction of several colleagues of a Dalton minimum. The North-South asymmetry in solar polar field is pronounced for the decay phase of cycles 23, 24, itseems to change sign after the Cycle 21. GCR flux in the stratosphere is greater that in 1965 and increasing, pointing to an enhanced radiation exposure in future for the passengers on transpolar flights, the astronauts on the space station as well as those travelling to and staying on the Moon and the Mars on prolonged missions; the assets in space would have to be hardened for safety from increased radiation. We speculate about the connection between the Earth climate and changes in solar activity, inferring that the science of the Earth climate change is not settled yet. (C) 2019 COSPAR. Published by Elsevier Ltd. All rights reserved.