[1] CAM3 configurations for my Bachelor works

CAM3 (T42) Experiments with LGM configurations (unavailable any more)

conducted by Wang Yue (163wangyue@163.com)

Complete Date: 2008-4-23 to 2008-6-21

 

General description:

CAM3.0, T42 resolution (grids 64×128), Last Glacial Maximum 21 kyr BP

Model Years of Run:

from model year 400 to 439, totally 40 years for each experiments.

Outputs: monthly means

 

Forcings

  • scon = 1.36500e+6 (solar constant = 1365.0 W/m^2)
  • orb_year = -19050 (relative to 1950: 1950-21000)
  • co2vmr = 2.00000e-4 (200 ppmv) (PMIP1 value)
  • ch4vmr = 3.50000e-7 (350 ppbv) (PMIP1 value)
  • n20vmr = 1.90000e-7 (190 ppbv) (PMIP1 value)
  • f11vmr = 0.0
  • f12vmr = 0.0

 

CAM Boundary Conditions

  • ozone = Present day value
  • sulfates = AerosolMass_V_1870_SO4_64x128_clim_c040224.nc (10 year average from b30.020; T85 1870)
  • dust & sea salt = present day prescribed
  • topography & ice sheet = ICE-5G(Peliter,2004)
  • coastline = ICE-5G(Peliter,2004) , corresponding to ~120 m lowering of sea level

 

sst&sea-ice(six schemes):

(1) CLIMAP

(2) wang( tropical Western Pacific )(Wang Pinxian,1999 reconstruction)

(3) osu(tropical Atlantic and eastern equatorial Pacific)(Mix,1999 reconstruction)

(4) wang_osu(combined (2) and (3))

(5) MARGO( LGM SST reconstruction from MARGO(2005))

the differences between (1)-(5) just lay on tropical SST, and SST on high latitudes are CLIMAP values. Sea-ice in (1)-(5) all take CLIMAP values.

(6) b30.104w(380-399 average SST and sea-ice) (provided by Nan Rosenbloom)

 

Generation of SST&Sea-ice boundary conditions:

(1) scatter data interpolation

Wang Pinxian(1999)’s 32-stations winter and summer sst are interpolated by surfer8 software using Kriging method. MARGO(2005)’s 391-station winter and summer sst (between 50ºS-50ºN) are interpolated by the same method.

(2) regional data inlay

Wang Pinxian’s (108ºE-168ºE,6ºS-40ºN) 2×2 degree data is inlaid into CLIMAP global 2×2 SST field. 7-points smoothing is applied in Boundary regions. So does MARGO’s winter and summer sst(180ºW-180ºE,50ºS-50ºN). MARGO’s sst between 30ºS-30ºN are directly used, while regions between 30ºN-50ºN and 30ºS-50ºS are first weight averaged by latitude distance, then applied 7-points smoothing.

(3) create osu global seasonality sst

We get the osu Feb and Aug sst by equations as follow:

osu_feb = climap_feb + (osu_ann-climap_ann)

osu_aug = climap_aug + (osu_ann-climap_ann)

(4) create wang_osu sst

Wang Pinxian’s (108ºE-168ºE, 6ºS-40ºN) 2×2 degree data is inlaid into osu global 2×2 SST field(Feb and Aug). 7-points smoothing is applied in Boundary regions.

(5) Now, we have got five global 2×2 ssts with mask provided by osu. Then we remove mask(land), and grids with land-ice/sea-ice are set to -1.8℃.

The results are interpolated into 1×1 grid (no mask) using surfer8. sea-ice/land-ice in the mask are converted to Feb and Aug sea-ice concentration, then interpolated into 1×1 grid using surfer8. Finally, 1×1 SST and Sea-ice are interpolated to 12-months value according to sine function and converted to 64×128 gauss grid by ncl software.

 

CLM surface boundary condition:

generated from LGM raw data by model:

mksrf_glacier_lgm.nc

mksrf_lanwat_lgm.nc

mksrf_pft_lgm.nc

other raw data take Present day values.

 

CAM Initial Conditions(*CLM initial conditions no specified)

branch from b30.104w, year 400 (PI 1780 control, T42x1)

 

Genreation of CAM initial condition(two schemes):

1.  Based on initial files of b30.104w, year 400 (CCSM3′ LGM T42_gx1v3 run (Otto-Bliesner,2006)), some variables are added in for the standalone run of CAM3:

(1) Using atm_dedinesurf program provided by Ian Eisenman, LANDM is created based on ICE-5G_v1.1_10min data, and varibles (PS, LANDFRAC, SGH, PHIS, LANDM_COSLAT) are created at the sametime. Because there have been PS, SGH, PHIS, LANDM_COSLAT in b30.104w initial file, only        LANDM is added.

(2) Varibles (TS, SNOWHICE, LANDFRAC, ICEFRAC) are abstracted from CAM history file of     b30.104w, December, year 399.

(3) TBOT is abstracted from CLM history file of b30.104w, December, year 399.

(4) TSICERAD, TSICE, TS1, TS2, TS3, TS4, TSOCN, SICTHK are abstracted from CAM3′ modern initial file.

final initial file name: cami_0400-01-01_64x128_L26_c080507.LGMfinal.nc

 

2. Based on initial files used in modern control experiment, we abstract LANDM, PS, SGH, PHIS, LANDM_COSLAT, TS, SNOWHICE, LANDFRAC, ICEFRAC from

cami_0400-01-01_64x128_L26_c080507.LGMfinal.nc,

and add these variables into modern initial file, the final initial file name is:

cami_0000-09-01_64x128_L26_c080507.LGM.nc

*** this scheme is only used to test how the differences of initial files influence the result.

=============================================================

Reference to: Modern control experiments: (1) GHG co2=355ppm, ch4=171.4ppb, N2O=311ppb; (2) orbital parameter at 1990 year (eccentricity=0.016724, Obliquity=23.446, Precession=102.04); (3) present day ice sheet and land-ocean distributions, climatological SST & sea ice distributions during 1981-2001 year; (4) solar constant=1365 W m-2.