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Interannual and decadal climate variability : Scale interaction experiments

Objective



Objectives :

To identify the patterns of the decadal variability in
the atmosphere and in the oceans and to identify the
nature of the variability. To identify the nature of
teleconnections in the tropical and midlatitudes regions,
especially with a link to the tropical biennial
cycle.

To investigate the nature of the contribution of
intraseasonal processes (MJO, Blocking) to the
interannual variability. To investigate possible
mechanisms for influences of the interannual variability
by the decadal variability (subduction, gyre dynamics,
etc...).

To investigate the links between the ENSO, the Asian
Summer Monsoon,
and the Tropical Atlantic

Brief Description of the Research Project :


Several research projects, either under way or about to
be completed, have shown the rich character of climate
variability at several time scales. It has been exposed
how several major time scales of variability are often
superposed and strongly interacting with each other. The
interannual time scale seems to play a pivotal role,
interacting strongly at the lower end of the spectrum
with intraseasonal variability, i.e. intraseasonal
oscillations of various kinds, among which the Madden-Julian Oscillation (MJO) is prominent. At the other end,
the interannual variability is affected by interactions
with longer time scales, as for instance, the Southern
Oscillation (SO) system.

Evidence is starting to emerge of a biennial cycle
connected with the ENSO-monsoon relation ship that has
not been sufficiently investigated. There are also clues
that ocean and atmosphere are coupled at the
intraseasonal time-scale and that this scale can interact
with the large scale variability of the system. For
instance, westerly wind
bursts in the Western Pacific are very important for
extracting heat from the ocean and for initiating
eastward motion of surface water. Whether these events
can act as a preconditioning of ENSO, or what other
function they have within the ENSO- Monsoon system, needs
clarification.

The overall target of SINTEX is to assess the possible
mechanisms of modulation by the decadal variability of
the interannual variations, and rather long simulations
(longer than 100 years) with coupled models with
realistic equatorial dynamics are needed.

The core numerical simulations will be performed by three
main coupled atmosphere/ocean model combinations, each of
them including state-of-the-art, advanced, global models:
A finite difference model both in the atmosphere and
ocean with high horizontal resolution in the ocean
(UKMO), a finite difference model with an original
coupling approach that allows evaluation of the model
physics on the ocean grid (LMD-OPA), a state-of-the-art
spectral model coupled to an advanced ocean model via a
coupler that guarantees energetic consistency in the
exchange (ECHAM4-OPA). The simulations will be
complemented by analysis of existing coupled simulations
and/or SST-prescribed experiments. ECHAM4-OPA will be
specially assembled for SINTEX by a transnational effort
of research groups in different European nations. The
horizontal resolution will be set at a moderate level
(spectral T30/T42 for the atmosphere and to 1-2 degrees
for the ocean, with equatorial enhancement of resolution
to 0.5 degrees) to allow long simulations, but at the
same time a very realistic simulations of tropical
interactions.

Coordinator

NATIONAL RESEARCH COUNCIL OF ITALY
Address
Via P. Gobetti 101
40129 Bologna
Italy

Participants (11)

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
France
Address
Ecole Polytechnique
91128 Palaiseau
CONSORZIO INTERUNIVERSITARIO PER LA GESTIONE DEL CENTRO DI CALCOLO ELETTRONICO DELL'ITALIA NORD ORIENTALE
Italy
Address
Via Magnanelli 6/3
Cantagallo
DANISH METEOROLOGICAL INSTITUTE
Denmark
Address
100,Lyngbyvej 100
2100 Koepenhagen
MAX-PLANCK-GESELLSCHAFT ZUR FOERDERUNG DER WISSENSCHAFTEN E.V.
Germany
Address
Bundesstra¯e 55
20146 Hamburg
NANSEN ENVIRONMENTAL AND REMOTE SENSING CENTER
Norway
Address
3A,edvard Griegsvej 3A
5059 Bergen
NEC Deutschland GmbH
Germany
Address
4,Emanuel-leutze-strasse
40547 Düsseldorf
ROYAL NETHERLANDS METEOROLOGICAL INSTITUTE
Netherlands
Address
10,Wilhelminalaan 10
3730 AE De Bilt
SECRETARY OF STATE FOR DEFENCE - MINISTRY OF DEFENCE
United Kingdom
Address
Fitzroy Road, Metz Office
EX1 3PB Exeter
UNIVERSITE PIERRE ET MARIE CURIE - PARIS VI
France
Address
Place Jussieu 4
75252 Paris
Universidad de Alcala de Henares
Spain
Address
20,Apartado
28880 Madrid
University of Reading
United Kingdom
Address
2 Earley Gate Whiteknights
RG6 6BB Reading