Scientific Focus
- Direct and indirect effects of energetic particle precipitation
- Related changes in the atmosphere, including the ionosphere
- Effects on middle atmospheric ozone, temperature, and dynamics
- Connections to ground level regional climate through dynamical coupling
Energetic particle precipitation (EPP) deposits solar energy
into the middle atmosphere and is an integral part of the
Sun-Earth connection. During precipitation events, the
particles can ionise and dissociate the neutral gases in
significant amounts and disturb the chemical balance of the
middle atmosphere. In chemical reactions between the neutral
and ionic gas constituents, the products of impact ionisation
and dissociation processes are converted to important minor
species, such as NO and OH. These minor components may affect
the ozone balance of the atmosphere because they can destroy
ozone in catalytic chemical reaction chains. Ozone is a key
constituent for the thermal balance and UV radiation
absorption characteristics of the atmosphere. Therefore, if
the particle events affect ozone, they can also affect the
atmosphere as a whole all the way down to ground level.
Growing concern about global change and the existence of an
anthropogenic component in climate variability challenge our
scientific understanding of the atmosphere. Still today we are
lacking exact knowledge on to what extent the solar
variability is causing natural variations in Earth's
atmosphere and climate. EPP has a well-known impact on
atmospheric ozone chemistry. However, the temporal variability
and strength of EPP depositing into the mesosphere and
stratosphere is poorly known. The big science question is the
resulting connection between ozone and atmospheric dynamics,
and thus the impact of EPP at ground-level, including the
occurrence of extreme winter weather. The nature of EPP
forcing makes it a prime candidate for increasing the skill of
long-range predictions on monthly-to-decadal timescales, but
this has not been explored. To isolate the full impact from
EPP a synergistic approach is needed, taking into account the
chemical-dynamical connections within the whole atmosphere
system.
We are aiming to solve the following science challenges:
characterise the energy-resolved flux of EPP consistent with
atmospheric observations; quantify the magnitude, temporal
variability, and spatial extent of EPP effects on the
atmosphere; determine the chemical and dynamical pathways by
which EPP effects propagate from the middle atmosphere to
Earth’s surface; and quantify the impact of EPP variability on
weather and climate predictability on monthly-to-decadal
timescales. To do this, we will need to combine a wide range
of magnetospheric, ionospheric, and atmospheric observations,
state-of-the-art chemistry-climate modelling of the whole
atmosphere, and long-range forecasting.