A Study of Physical-Chemical Effects on the Atmosphere of the Southern Hemisphere During Forbush Decrease Periods

Abstract:

We present here a study about some possible physical-chemical changes on the Southern hemisphere atmosphere, in Brazil, due to galactic cosmic rays (GCR) flux decreases (Forbush Decreases). Galactic Cosmic Rays are energetic particles that come from interstellar medium and arrive on the Earth isotropically and continuously. These particles interact with atmosphere constituents and induce the ionization of the neutral atmosphere. It is known that the presence of ions on the troposphere can change the vapor condensation patterns, since some ions can behave like cloud condensation nuclei. So, there is a work hypothesis, that the GCR flux decrease can cause some change on the physical-chemical of the atmosphere. We have investigated this possible effect, using three periods of Forbush Decrease effects (Nov/01, Oct/03 e Jul/12) with different magnitudes, on three different latitudinal range of Brazilian sector, Porto Alegre (30.08^o S , YY O); Brasília (15.75^o S , YY O) and Belém (1.46^o S , YY O). The atmospheric effects are assessed by analysis of the temperature, pressure, humidity and aerossol data profiles, since the surface up to stratosphere. We have also studied, for comparison, high latitude atmosphere by atmospheric data from Jokioinen - Filand (60.8^o N , 23.5^o E) for the same three FDs. Then, our aim with this study is to investigate possible GCR decreases effects in the lower atmosphere at high, medium and low latitudes. The results obtained in this study will be compared with previous published works.