Open AccessDust charging and electrical conductivity in the day and nighttime atmosphere of Mars
Author(s) -
Michael M.,
Tripathi S. N.,
Mishra S. K.
Publication year - 2008
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007je003047
Subject(s) - aerosol , ion , mars exploration program , atmosphere (unit) , atmosphere of mars , ionization , ionosphere , electron , atomic physics , atmospheric sciences , physics , martian , astrobiology , meteorology , astronomy , quantum mechanics
Understanding aerosol charging and atmospheric conductivity are necessary in describing the global electric circuit, the aerosol coagulation rate, aerosol‐cloud interaction and their subsequent affect on the climate. The importance of aerosol charging for the conductivity variations of the lower Martian atmosphere during both day and night is calculated. Galactic cosmic rays are the dominant ionizing agent in the lower atmosphere, producing molecular ions and ion clusters. During the nighttime these ion clusters get attached to the aerosols and charging occurs. Solar UV photons are an additional ionizing agent during the day‐time. Only solar photons of energy less than 6 eV reach the surface of Mars as those with energies greater than 6 eV are absorbed by atmospheric molecules before they reach the lower atmosphere. Those photons which do reach the lower atmosphere ionize the aerosols as the ionization potential of most of the aerosols is less than 6 eV and produce electrons. Aerosols become charged by the attachment of ions and electrons during the day‐time. The ion‐aerosol and electron‐aerosol attachment coefficients, as well as the ion‐ion and ion‐electron recombination rates are calculated. The charge distribution of aerosols is obtained by the simultaneous solution of the ion‐aerosol charge balance equations. Both the steady state and time dependent concentration of charged aerosols are calculated. More than 60% of the ions and 95% of the electrons get attached to the aerosols. There are more negatively charged aerosols in steady state due to the presence of highly mobile electrons during the day‐time. The presence of electrons increases the conductivity during the day time. The day‐time results are compared with the nighttime results.