The Abdus Salam       International Centre for Theoretical Physics

RegCM3 sensitivity to driving data, RegCM3 sensitivity to driving data, resolution and resolution and

large scale circulation forcing large scale circulation forcing over the Black Sea domainover the Black Sea domain

C. Boroneant (Romania), V. Barabanov (Ukraine),C. Boroneant (Romania), V. Barabanov (Ukraine), V. Alexandrov (Bulgaria)V. Alexandrov (Bulgaria)

Group 17Group 17

Trieste, 2003Trieste, 2003

MOTIVATIONMOTIVATION

• Geographic domain Geographic domain

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

Domain Topograhy (in m)

PROJECT OBJECTIVESPROJECT OBJECTIVES

Examine the influence of the input boundary Examine the influence of the input boundary

conditions on model resultsconditions on model results

Examine the model ability in simulating the Examine the model ability in simulating the regional climate over the Black Sea & adjacent regional climate over the Black Sea & adjacent regionsregions

Examine the precipitation field under different Examine the precipitation field under different NAO phasesNAO phases

MODEL SETTINGSMODEL SETTINGS

iy = 34 (68) - grid points on latitudeiy = 34 (68) - grid points on latitude

jx = 51 (102) - grid points on longitudejx = 51 (102) - grid points on longitude

kz=18 - sigma levelskz=18 - sigma levels

ds = 50 (25) - resolution 50 (25) km)ds = 50 (25) - resolution 50 (25) km)

clat = 45.00clat = 45.00

clon = 32.00clon = 32.00

ntypec = 36 (10’ resolution for global terrain and land-use)ntypec = 36 (10’ resolution for global terrain and land-use)

iproj = ‘LAMCON’ (Lambert conformal map projection)iproj = ‘LAMCON’ (Lambert conformal map projection)

Grell Cummulus parametrization schemeGrell Cummulus parametrization scheme

January January 1993, 1994, 1995, 1996, 19971993, 1994, 1995, 1996, 1997

MODEL RUNSMODEL RUNS

3 different driving data3 different driving dataECMWF + OISST (1993, 1994, 1995, 1996, 1997)ECMWF + OISST (1993, 1994, 1995, 1996, 1997)

NNRP2 + OISST (1993)NNRP2 + OISST (1993)ECMWF + GISST (1995)ECMWF + GISST (1995)

2 different resolutions (the same domain size)2 different resolutions (the same domain size)34x51x18 (50 km) 34x51x18 (50 km) (1995; ECMWF+OISST) (1995; ECMWF+OISST)

68x102x18 (25km)68x102x18 (25km)

2 different large scale circulation conditions 2 different large scale circulation conditions NAO+ 1993; 1994, 1995 (ECMWF+OISST)NAO+ 1993; 1994, 1995 (ECMWF+OISST)

NAO- 1996, 1997NAO- 1996, 1997

Comparison Comparison CRU –data RegCM (ECMWF+OISST)CRU –data RegCM (ECMWF+OISST)

RegCM Precipitation rate (mm/day) January 1993

ECMWF +OISST NNRP2 +OISST

RegCM Precipitation rate (mm/day) January 1995

ECMWF +OISST ECMWF +GISST

RegCM - different resolutions (the same domain )RegCM - different resolutions (the same domain )

January 1995; ECMWF+OISSTJanuary 1995; ECMWF+OISST

50 km 50 km 25 km25 km

precipitation rate (mm/day)precipitation rate (mm/day)

spatial avg. Jan. 1995 spatial avg. Jan. 1995

RegCM3 precipitation rate (mm/day)RegCM3 precipitation rate (mm/day)

Res 50 Km ; res 25 km

SLP RMSE (RegCM vs ECMWF), 25 km

NAO Index and related weather conditionsNAO Index and related weather conditions

1996

1993

http://www.cdc.noaa.gov

Correlation map between surface precipitation rate (Dec-Feb) Correlation map between surface precipitation rate (Dec-Feb) and the NAO Index, 1949-2000and the NAO Index, 1949-2000

ComparisonComparison between RegCM (ECMWF+OISST) and CRUbetween RegCM (ECMWF+OISST) and CRU

driven by different large scale circulation conditions driven by different large scale circulation conditions Jan Jan 1993 NAO+ Jan 1996 NAO-

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.

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