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Content archived on 2024-05-07

Atmospheric Circulation Classification and Regional Downscaling


Objectives :

To evaluate existing methodologies for classifying
atmospheric circulation patterns, to automate them and to
develop new automated schemes.

To use these automated schemes to further understanding
of climatic variability since the late nineteenth
century, and of the physical links between circulation at
different space-scales and between circulation modes and
synoptic features.

To determine the importance of, in particular, the North
Atlantic Oscillation (NAO) with respect to the
variability of surface temperature and precipitation
across Europe.

To improve the potential of the circulation
classification approach for downscaling by optimising the
discrimination of observed surface weather variables, and
assessing stationarity of relationships at different
space scales.

Brief Description of the Research Project :

Much effort is devoted to GCM (and higher resolution)
simulations of present climate and the projection of
future climates. Across Europe, impact studies are
dependent on climate scenarios generated by
"downscaling" from such models. The assumptions upon
which such scenarios are based are too rarely tested at
the regional and sub-regional scales. A prime reason for
this inadequate testing is the current absence of robust,
automated, methodologies for classifying circulation

ACCORD will undertake a comprehensive assessment of
existing methods of circulation classification, and will
develop emerging techniques to produce automated schemes,
taking into account space-scales, transportability,
powers of discrimination and robustness. The primary
information will be surface pressure observations from
1881, but upper air and Reanalysis data will also be
used. ACCORD will also examine whether clustering of
surface weather variables provides more discriminating
power than spatial pattern recognition schemes for
pressure. ACCORD will then characterise North Atlantic
and European circulation variability over 115 years,
across a range of time- and space-scales.

One of ACCORD's main aims will be an identification of
the influence of the NAO - the most important controlling
circulation characteristic for Europe - for seasonal,
annual and multiannual distributions of temperature and
precipitation. The recent increases in precipitation over
many areas of northwest Europe will be examined for links
both with large-scale and sub-regional circulations.

The adopted automated circulation classification schemes
(on a number of space-scales) will be used to better
discriminate (hence, optimise) observed surface variables
(i.e. improve downscaling) in a number of European sub-regions. Various methods will be used, including
multivariate stochastic models, weather generators,
mutiple regression models, and non-linear techniques.
Particular attention will be paid to the extent to which
the schemes are able to capture the full range of
climatic variability, especially extreme events, and to
the question of time stationarity of observed
circulation/surface weather relationships.

Call for proposal

Data not available


EU contribution
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University Plain
United Kingdom

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Total cost
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Participants (9)