The Abdus Salam

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The Abdus Salam       International Centre
for Theoretical Physics
RegCM3 sensitivity to driving data, resolution
and large scale circulation forcing over the
Black Sea domain C. Boroneant (Romania), V.
Barabanov (Ukraine), V. Alexandrov
(Bulgaria) Group 17 Trieste, 2003
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MOTIVATION

• Geographic domain with complex topography
• Improve understanding of regional climate
• Interest in selection of best data sets to
  drive the model (initial and boundary
  conditions)
• Interest in seasonal anomalies related to the
  large scale forcing (in the North Atlantic,
  Mediterranean)

Domain Topograhy (in m)
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PROJECT OBJECTIVES
? Examine the influence of the input boundary
conditions on model results ? Examine the model
ability in simulating the regional climate over
the Black Sea adjacent regions ? Examine the
precipitation field under different NAO phases
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MODEL SETTINGS
? iy 34 (68) - grid points on latitude ? jx
51 (102) - grid points on longitude ? kz18 -
sigma levels ? ds 50 (25) - resolution 50 (25)
km) ? clat 45.00 ? clon 32.00 ? ntypec
36 (10 resolution for global terrain and
land-use) ? iproj LAMCON (Lambert conformal
map projection) ? Grell Cummulus parametrization
scheme
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January 1993, 1994, 1995, 1996, 1997
MODEL RUNS
? 3 different driving data ECMWF OISST
(1993, 1994, 1995, 1996, 1997) NNRP2 OISST
(1993) ECMWF GISST
(1995) ? 2 different resolutions (the same
domain size) 34x51x18 (50 km) (1995
ECMWFOISST) 68x102x18 (25km) ? 2 different
large scale circulation conditions NAO 1993
1994, 1995 (ECMWFOISST) NAO-
1996, 1997
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Comparison CRU data
RegCM (ECMWFOISST)
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(No Transcript)
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RegCM Precipitation rate (mm/day) January 1993
ECMWF OISST
NNRP2 OISST
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RegCM Precipitation rate (mm/day) January 1995
ECMWF OISST
ECMWF GISST
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RegCM - different resolutions (the same domain )
January 1995 ECMWFOISST
precipitation rate (mm/day)
50 km
25 km
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RegCM3 precipitation rate (mm/day)
spatial avg. Jan. 1995
Res 50 Km res 25 km
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SLP RMSE (RegCM vs ECMWF), 25 km
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1993
1996
NAO Index and related weather conditions
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Correlation map between surface precipitation
rate (Dec-Feb) and the NAO Index, 1949-2000
http//www.cdc.noaa.gov
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Comparison between RegCM (ECMWFOISST) and
CRUdriven by different large scale circulation
conditions Jan 1993 NAO
Jan 1996 NAO-
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Concluding remarks

• No significant differences in precipitation when
  using ECMWF or NNRP2 datasets neither for OISST
  or GISST have been found
• Some differences between observations in CRU data
  and RegCM precipitation are shown in our
  simulations
• Mezoscale features of precipitation are better
  represented in the higher resolution simulations
• RegCM is able to reproduce different regional
  precipitation patterns according to the large
  scale circulation regime related to the NAO
  phases, but shows some differences in comparison
  to CRU observations.

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Interest in further work

• Enlarge the domain
• Longer period (20-30 years)
• Look at seasonal variability (DJF, JJA) in the
  domain forced by circulation regimes in the North
  Atlantic and the Mediterranean
• Climate change scenarios in the region