Geomagnetic field and climate variability. 1. Spatial-temporal distribution of geomagnetic field and climatic parameters during XX century

Abstract

Analysis of main geomagnetic field (from IGRF model) and climatic parameters (near surface air temperature and surface pressure) allows us to determine their variability and spatial-temporal relations between them during the 20th. Integral characteristics and dynamics of the above parameters in latitudinal band 40-70 ° N have been investigated, applying one and the same approach. This gives us the possibility to reveal their global and regional characteristics - the differences and similarities between them. Three distinct periods of the spatial-temporal distribution of geomagnetic field intensity have been determined, that could be connected to corresponding periods of mean near surface air temperature evolution during the 20th century: initial global warming (1911-1943); stabilization (end of 1940 s - middle 1970 s); secondary global warming (middle of 1970 s - 2000 s). There is a good correspondence between geomagnetic field, near surface air temperature and pressure spatial distributions during the 20th century. The high coefficient of similarity between integral spatial distributions of geomagnetic field intensity F and surface air temperature T (RFT ) = - 0,83 is quite unexpected. It indicates that relations between them could hardly be a random connection. If there is a causal relation between them, it obviously should be in the direction: geomagnetic filed influence on the temperature and / or surface pressure. The main problem in this case is that the mechanisms of magnetic filed influence on climatic parameters are less investigated and poorly understood. In this paper geomagnetic field is considered to be a first element of the causal chain of processes relating it with Earth's climate. A brief review of resent understanding of solar - geomagnetic field influence on climate shows that the main role in this process is played by galactic cosmic rays. Results presented here are basement for the second part of this paper, where the causal link of the processes connecting geomagnetic field with galactic cosmic rays, ozone and water vapour near the tropopause (with their influence on the radiation balance of the planet and consequently on climate) is thoroughly analysed.