CERFACS CERFACS Scientific Activity Report Jan. 2010 – Dec. 2011

TABLE DES FIGURES
3 Data Assimilation 71
2.1 Left panel : vertical profiles of the 2004-2008, globally averaged specified (solid curves)
and diagnosed (dashed curves) standard deviations of background salinity error before
tuning (red curves) and after tuning (blue curves). Right panel : globally averaged rootmean-square
salinity errors (background-minus-observations) before and after tuning of the
background-error standard deviations (red and blue curves, respectively). The horizontal
axis is in psu ; the vertical axis is depth in metres. . . . . . . . . . . . . . . . . . . . . . . 75
3.1 Diagnosed length-scales (in km) of the horizontal correlation of the forecast error, averaged
on the period between 1 st and 10 th July 2010 : West-East (left) and North-South (right)
length-scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.2 Zoom over the South Pole between 70 ◦ S–40 ◦ S and 20 ◦ E–60 ◦ E of the situation for the 30 th
September 2008. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.3 Mean (top) and standard deviation (bottom) of the difference in terms of total ozone
column (in %) between the OMI (independent) data and the model without assimilation
(grey shaded area) or the analyses as a function of latitude, for January, April, July and
October 2008. For the top panel, positive (negative) values stand for an underestimation
(overestimation) of the model or the analyses compared to OMI data. The analyses differ
from the modelling of the BECM : simple formulation (blue line) or from ensemble-based
diagnostics (red line). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4 CO concentration (in ppbv) at 500 hPa for the 19 th January 2008. . . . . . . . . . . . . . 82
4.1 Reduction of the uncertainty in the rainfall data using data assimilation. Comparison of
Nash criteria before (background) and after (analysis) data assimilation. . . . . . . . . . . 85
4.2 Improvement of Nash criteria (IE) and peak height with rain fall data correction computed
with MFB and data assimilation, by event (the event label is month-year-peaknumber). . . 86
4.3 April 2006 event, Marne Vallage catchment. Two-hour forecasted water level at Joinville
for the Free run (black curve), the observation (blue curve) and the analysis of the Assim
run with the two-step assimilation (red curve). . . . . . . . . . . . . . . . . . . . . . . . . 87
5.1 Improvement of fire front propagation with fire front position data assimilation . . . . . . 90
4 Coupling tools and HPC Climate Modeling 97
5 Climate Variability and Global Change 113
2.1 Anomalous global SST from observation (black) and for decadal forecasts (colors)
initialized on Jan 1, 1960, 1965, 1970, ..., 2005. Each spaghetti corresponds to one member.
The reference period is 1970-1990. Major volcanic eruptions are mentionned . . . . . . . 119
2.2 AMO predictability for 1 year (left), 2-6 years (middle) and 6-10 years (right) leadtime from
decadal forecasts (blue) and historical simulations (red). Correlations between ensemble
mean and observation (black) are given in the upper-left corners of the panels. The pink
shading stands for the ensemble spead of the historical experiments. . . . . . . . . . . . . 119
x Jan. 2010 – Dec. 2011