[Todos] corrección COLOQUIO: miercoles 9/4

[coloquios]

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                          Coloquio del
  Departamento de Ciencias de la Atmósfera y los Océanos DCAO)/
      Centro de Investigaciones del Mar y la Atmósfera (CIMA)

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MIÉRCOLES 9 DE ABRIL, 13-14 HS, Aula 8 DCAO, 2°piso

Climate model genealogy: Generation CMIP5 and how we got there &
Long-term variations and trends of mesoscale precipitation in the 
Alpine region: Recalculation and update for 1901-2008.

David Masson
Federal Office of Meteorology and Climatology MeteoSwiss, Switzerland

Climate model genealogy: Generation CMIP5 and how we got there

Reto Knutti (1), David Masson (2) and Andrew Gettelman (3)

Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland
Federal Office of Meteorology and Climatology MeteoSwiss, Switzerland
National Center for Atmospheric Research, Boulder, Colorado, USA
Climate change projections are often given as equally weighted averages 
across ensembles of climate models, despite the fact that the sampling 
of the underlying ensembles is unclear. We show that a hierarchical 
clustering of a metric of spatial and temporal variations of either 
surface temperature or precipitation in control simulations can capture 
many model relationships across different ensembles. Most of the of the 
CMIP5 models are strongly tied to their CMIP3 predecessors, and some 
also exchange ideas and code with other modeling institutions, thus 
supporting an earlier hypothesis that the models in the new ensemble are 
not independent of each other, nor independent of the earlier 
generation. Based on one atmosphere model, we show how statistical 
methods can identify similarities between model versions and complement 
process understanding in characterizing how and why a model has changed. 
We argue that the inter-dependence of models complicates the 
interpretation of multi model ensembles, but largely goes unnoticed.


(2)
Long-term variations and trends of mesoscale precipitation in the 
Alpine region: Recalculation and update for 1901-2008.

David Masson and Christoph Frei

Federal Office of Meteorology and Climatology MeteoSwiss, Switzerland

In this study, a new grid dataset of monthly precipitation covering the 
entire region of the European Alps and the period 1901–2008 is presented 
and allows the study of long-term variations and trends in Alpine 
precipitation. The construction of this dataset is based on a 
statistical method that interweaves information from a high-resolution 
reference dataset over a short period with that from long-term, yet 
sparse station series. This technique is comparatively robust against 
variations in the station density and inhomogeneities in the data, while 
it preserves characteristic mesoscale patterns of the variability. A 
detailed evaluation of the procedure reveals that monthly precipitation 
totals can be reconstructed with an explained variance of between 60 and 
95%, with variations in skill reflecting the density of long-term 
station records. The new dataset reveals considerable interannual to 
inter-decadal variations with marked differences between major 
sub-regions of the Alps and calls for caution in the interpretation of 
trend analyses. The presented dataset offers itself for more detailed 
analyses on the relation to large-scale circulation and long-term 
climate change.

¡Los esperamos a todos!
Aula 8 DCAO, 2°piso

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Grupo Coloquios
Departamento de Ciencias de la Atmosfera y los Oceanos (FCEN-UBA)
Centro de Investigaciones del Mar y la Atmosfera (CONICET-UBA)
Ciudad Universitaria, 2do piso.
email: coloquios en at.fcen.uba.ar
http://www.at.fcen.uba.ar/charlas_not.php
http://www.cima.fcen.uba.ar/espanol/index.htm
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