National Institute of Geophysics, Geodesy and Geography, Bulgaria
Title: The role of geomagnetic field in the spatial-temporal climate variability
The area of expertise of prof. N. Kilifarska covers the wide spectrum of topics – from the Sun, through interplanetary magnetic field, magnetosphere and ionosphere, down to the stratosphere and Earth’s climate. The last 15 years she spent in analyses of factors influencing climate variability. After years of thorough studies of connectivity between ozone, GCR and geomagnetic field, she has discovered that lower energetic electrons in Pfotzer maximum could initiate an autocatalytic ozone production in the driest region above the tropopause. Later she found out that depending of the elevation of Pfotzer maximum, the ion-molecular chemistry near the tropopause could produce or destroy ozone. Combined with the heterogeneous geomagnetic field, this finding is able to explain the asymmetrical ozone distribution over the globe. Furthermore, the O3 influence on the tropopause temperature and humidity transposes the particles’ effect down to the Earth surface through the modulation of near tropopause water vapor and its greenhouse effect.
The regionality of climate variations is one of the challenging problems for the climatologists – given that the main source of energy of the climate system(i.e. the solar irradiance) is zonally homogeneous. Attempts to bring the problem to the internal climatic modesdo not solve it, because first we have to understand the factors and mechanisms driving the internal climate variability. We offer another explanation ofthe regional specificity of climate variations, based on a causal chain of relations between geomagnetic field →galactic cosmic rays (GCR)→near tropopause ozone and water vapor1. In contrast to the existing modelings2, 3 of the GCR effect on atmospheric O3, we have focused our attention on the lower energetic electrons created near the tropopause, known as the Pfotzer maximum, and initiated by them ion-molecular reactions. We have shown that depending on the level of Pfotzer maximum ion-molecular chemistrycould produceor destroy the ozone4. Statistical analysis of the ERA 20 century reanalysis and long-term variations of GCR confirms the different sensitivity and even different sign of GCR-ozone relation (Fig.1).Note the synchronous variations in phase GCR-ozone covariance in tropics and Polar Regions and antiphase covariance near 500 latitudes. These asymmetries in ozone response to particle forcing should be attributed to:(i) the gradient–curvature drift of trapped in geomagnetic field particles –focusing particles’ precipitations in some regions over the planet; (ii) the different altitude of Pfotzer maximum, determined by the particles’ energy and magnetic field strength1,5.
The importance of the near tropopause ozonedensityfor the climate variability is fairly well documented. We show, in addition, that the ozone influence on the tropopause temperature and static stability of the upper troposphere controls the amount of the water vapor near the tropopause, and consequently the strength of its greenhouse effect1.Thus the regional differences of GCR impact on the near tropopause ozone density are imprinted on the surface temperature through the near tropopause water vapor.