  Observations and simulations show that Mars' atmosphere has large seasonal
variations. Total atmospheric density can have an order of magnitude
latitudinal variation at exobase heights. By numerical simulations we show that
these latitude variations in exobase parameters induce asymmetries in the
hydrogen exosphere that propagate to large distances from the planet. We show
that these asymmetries in the exosphere produce asymmetries in the fluxes of
energetic neutral atoms (ENAs) and soft X-rays produced by charge exchange
between the solar wind and exospheric hydrogen. This could be an explanation
for asymmetries that have been observed in ENA and X-ray fluxes at Mars.
