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Computing Monthly bias-corrected SSTs for CCAM

Computing Monthly bias-corrected SSTs for CCAM. Jack Katzfey, J McGregor, K Nguyen and M Thatcher Mesoscale Modelling Team 27 May, 2009. Outline. Get GCM monthly SST data (PCMDI) Compute monthly GCM climatological SSTs (1961-2000) on CCAM grid

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Computing Monthly bias-corrected SSTs for CCAM

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  1. Computing Monthly bias-corrected SSTs for CCAM Jack Katzfey, J McGregor, K Nguyen and M Thatcher Mesoscale Modelling Team 27 May, 2009

  2. Outline • Get GCM monthly SST data (PCMDI) • Compute monthly GCM climatological SSTs (1961-2000) on CCAM grid • Get ‘observed’ monthly climatological SSTs (Reynolds) on CCAM grid • For each year and month of GCM SST data: • Get data • Interpolate to model grid • Compute new SST=mts-(mgcm-clim) • Write ascii file • Interpolate monthly Sea Ice Fraction to CCAM grid and write ascii file

  3. Procedure Get GCM monthly SST data (PCMDI) Compute monthly GCM climatological SSTs (1961-2000) Interpolate GCM SST to model grid (one) : meantsu.sh Need GCM land mask $ncks –O –d time,t gcmts.nc ts.year.mon.nc $ncrcat –O ts.*.mon.nc gcmts.mon.nc $ncra –O gcmts.mon.nc avg_gcmts.mon.nc Run “one” to interpolate avg_gcmts.mon.nc to avg_gcm_dom.mon.nc

  4. Procedure Get ‘observed’ monthly climatological SSTs (Reynolds) Interpolate Reynolds SST to model grid (one) : mktsu.sh For each month, interpolate Reynolds to CCAM grid using “one” Only need to run once for each CCAM grid

  5. Procedure For each year and month of GCM SST data wanted : amip.sh Interpolate SST data to CCAM grid (one) : mts Need GCM land mask (make sure 0-1) Loop over all years wanted Loop over all 12 months $ncks –O –d time,ta gcmts.nc ts.nc $ncrename –v ts,tss ts.nc $ncatted –O –a point_spacing,time,d,, ts.nc $ncatted -O -a time_origin,time,d,, ts.nc $ncatted -a units,time,m,c,"days since $ybasec-01-01 00:00" ts.nc Run “one” to interpolate to CCAM grid : mts

  6. Procedure Get mean Reynolds SST for this month on CCAM grid : oclim Get mean GCM SST for this month on CCAM grid : gcm Compute bias corr. SST : bcts = mts – (gcm-oclim) $ncrename -O -v tsu,oclim $oclimts ntss.nc $ncrename -O -v ts,gcm $gcmts gtss.nc $ncap -O -s "mts=float(abs(tss))" mts.nc tsall.nc $ncks -A -v gcm gtss.nc tsall.nc $ncks -A -v oclim ntss.nc tsall.nc Write data in ascii format : (bcts-273.16+50)*100 $ncap -O -s 'bct1=mts-(gcm-oclim);where(bct1>200);bcts=bct1;elsehere;bcts=200;tsu=(bcts-273.16+50)*100.' tsall.nc ts.nc $nc2text -p -n 64 -f "%5.0f" 'ts.nc tsu' >> $tstxt

  7. Procedure For each year and month of GCM Sea Ice Fraction data: Get data ($ncks) Interpolate to model grid (“one”) $ncap -O -s 'fi=float(fracice)' msic.nc fi.nc $nc2text -p -n 64 -f "%4.0f" 'fi.nc fi' >> $fitxt

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