A Conceptual Framework for Time and Space Scale Interactions in
the Climate System
Gerald Meehl, Roger Lukas, George Kiladis, Klaus Weickmann, Adrian Matthews, and Matthew Wheeler
2001, Climate Dynamics, 17, 753-775.
Abstract
Interactions involving various time and space scales,
both within the tropics and between the tropics
and midlatitudes, are ubiquitous in the climate
system. We propose a conceptual framework for understanding such interactions
whereby longer
time scales and larger space scales set
the base state for processes on shorter
time scales and smaller space scales, which in turn have an influence back on
the longer time scales and larger space scales in a continuum of
process-related interactions. Though not intended to be comprehensive,
instead we cite examples from the literature to provide evidence for the
validity of this framework.
Decadal time scale base states of the coupled
climate system
set the context for the manifestation of
interannual time scales (El Nino/Southern Oscillation, ENSO
and tropospheric biennial oscillation, TBO)
which are influenced by and
interact with the annual cycle and seasonal time scales.
Those base states in turn influence the
large-scale coupled processes involved with intraseasonal and submonthly
time scales, tied to tropical-tropical and tropical-midlatitude
teleconnections.
All of these set the base state for processes on
the synoptic and mesoscale and
regional/local space scales.
Events at those relatively short time scales and small
space scales may then affect the longer
time scale and larger space scale processes in turn, reaching back out to
submonthly, intraseasonal, seasonal, annual, TBO, ENSO and decadal.
Global coupled models can capture some elements of the decadal, ENSO, TBO,
annual and seasonal time scales with the associated global space scales.
However, coupled models are less successful at simulating
phenomena at subseasonal and
shorter time scales
with hemispheric and smaller space scales.
In the context of the proposed conceptual framework,
the synergistic interactions of the time and space scales suggest that
a high priority must be placed on improved simulations
of all of the time and space scales in the climate system. This is
particularly important for
the subseasonal time scales and
hemispheric and smaller space scales,
which are not well simulated at present,
to improve the prospects of successfully forecasting
phenomena beyond the synoptic scales.