CDO

Dear Sir/Madam,

CDO is very powerful software to post the NC data. Now I have a model data on sigma level. I want to perform vertical interpolation from sigma to pressure level. When I type this command
cdo ml2pl,100000,92500,85000,77500,70000,60000,50000,40000,30000,25000,20000,15000,10000,7000,5000,3000,1000 ctrl_experiment_1.u.nc out.nc, the warning is as follows:
cdo ml2pl (Abort): surface_air_pressure not found!

By the way, the CDO version is 1.6.6. could you give me some suggestion on how to succeed in changing vertical resolution without surface pressure? because it is not available for me to get the pressure data.

Please find the attached ECHAM output data.

Thanks in advance

Yong

netcdf ctrl_experiment_1.u {
dimensions:
lon = 96 ;
lat = 48 ;
lev = 19 ;
nhym = 19 ;
nhyi = 20 ;
time = UNLIMITED ; // (12 currently)
variables:
double lon(lon) ;
lon:standard_name = "longitude" ;
lon:long_name = "longitude" ;
lon:units = "degrees_east" ;
lon:axis = "X" ;
double lat(lat) ;
lat:standard_name = "latitude" ;
lat:long_name = "latitude" ;
lat:units = "degrees_north" ;
lat:axis = "Y" ;
double lev(lev) ;
lev:standard_name = "hybrid_sigma_pressure" ;
lev:long_name = "hybrid level at layer midpoints" ;
lev:units = "level" ;
lev:positive = "down" ;
lev:formula = "hyam hybm (mlev=hyam+hybm*aps)" ;
lev:formula_terms = "ap: hyam b: hybm ps: aps" ;
double hyai(nhyi) ;
hyai:long_name = "hybrid A coefficient at layer interfaces" ;
hyai:units = "Pa" ;
double hybi(nhyi) ;
hybi:long_name = "hybrid B coefficient at layer interfaces" ;
hybi:units = "1" ;
double hyam(nhym) ;
hyam:long_name = "hybrid A coefficient at layer midpoints" ;
hyam:units = "Pa" ;
double hybm(nhym) ;
hybm:long_name = "hybrid B coefficient at layer midpoints" ;
hybm:units = "1" ;
double time(time) ;
time:standard_name = "time" ;
time:units = "days since 848-12-31 18:00:00" ;
time:calendar = "proleptic_gregorian" ;
float u(time, lev, lat, lon) ;
u:long_name = "u-velocity" ;
u:units = "m/s" ;
u:code = 131 ;
u:table = 128 ;
u:grid_type = "gaussian" ;

// global attributes:
:CDI = "Climate Data Interface version 1.5.3 (http://code.zmaw.de/projects/cdi)" ;
:Conventions = "CF-1.4" ;
:history = "Sun Jan 29 08:59:30 2012: cdo setreftime,848-12-31,18:00 -mulc,1 -ymonmean code_131_merged.nc tmp\n",
"Sun Jan 29 08:59:25 2012: cdo mergetime code_131_082001.nc code_131_082002.nc code_131_082003.nc code_131_082004.nc code_131_082005.nc code_131_082006.nc code_131_082007.nc code_131_082008.nc code_131_082009.nc code_131_082010.nc code_131_082011.nc code_131_082012.nc code_131_082101.nc code_131_082102.nc code_131_082103.nc code_131_082104.nc code_131_082105.nc code_131_082106.nc code_131_082107.nc code_131_082108.nc code_131_082109.nc code_131_082110.nc code_131_082111.nc code_131_082112.nc code_131_082201.nc code_131_082202.nc code_131_082203.nc code_131_082204.nc code_131_082205.nc code_131_082206.nc code_131_082207.nc code_131_082208.nc code_131_082209.nc code_131_082210.nc code_131_082211.nc code_131_082212.nc code_131_082301.nc code_131_082302.nc code_131_082303.nc code_131_082304.nc code_131_082305.nc code_131_082306.nc code_131_082307.nc code_131_082308.nc code_131_082309.nc code_131_082310.nc code_131_082311.nc code_131_082312.nc code_131_082401.nc code_131_082402.nc code_131_082403.nc code_131_082404.nc code_131_082405.nc\n",
"Sun Jan 29 08:59:12 2012: cdo selcode,131 /sx8/user1/stepanek/cosmos/Leeds/Pliocene/PlioMIP/ctrl-as_280ppm/outdata/echam5/ctrl-as_280ppm_echam5_main_mm_084912.nc code_131_084912.nc\n",
"Wed Jan 25 10:25:21 2012: cdo -f nc merge /sx8/user1/stepanek/cosmos/Leeds/Pliocene/PlioMIP/ctrl-as_280ppm/outdata/echam5/ctrl-as_280ppm_echam5_ATM_mm_084912.grb /sx8/user1/stepanek/cosmos/Leeds/Pliocene/PlioMIP/ctrl-as_280ppm/outdata/echam5/ctrl-as_280ppm_echam5_BOT_mm_084912.grb /sx8/user1/stepanek/cosmos/Leeds/Pliocene/PlioMIP/ctrl-as_280ppm/outdata/echam5/ctrl-as_280ppm_echam5_main_mm_084912.nc" ;
:source = "ECHAM5.4" ;
:institution = "Max-Planck-Institute for Meteorology" ;
:CDO = "Climate Data Operators version 1.5.3 (http://code.zmaw.de/projects/cdo)" ;
data:

lon = 0, 3.75, 7.5, 11.25, 15, 18.75, 22.5, 26.25, 30, 33.75, 37.5, 41.25, 
    45, 48.75, 52.5, 56.25, 60, 63.75, 67.5, 71.25, 75, 78.75, 82.5, 86.25, 
    90, 93.75, 97.5, 101.25, 105, 108.75, 112.5, 116.25, 120, 123.75, 127.5, 
    131.25, 135, 138.75, 142.5, 146.25, 150, 153.75, 157.5, 161.25, 165, 
    168.75, 172.5, 176.25, 180, 183.75, 187.5, 191.25, 195, 198.75, 202.5, 
    206.25, 210, 213.75, 217.5, 221.25, 225, 228.75, 232.5, 236.25, 240, 
    243.75, 247.5, 251.25, 255, 258.75, 262.5, 266.25, 270, 273.75, 277.5, 
    281.25, 285, 288.75, 292.5, 296.25, 300, 303.75, 307.5, 311.25, 315, 
    318.75, 322.5, 326.25, 330, 333.75, 337.5, 341.25, 345, 348.75, 352.5, 
    356.25 ;

lat = 87.1590945558629, 83.4789366693172, 79.7770456548256, 
    76.0702444625451, 72.3615810293448, 68.6520167895175, 64.9419494887575, 
    61.2315731880771, 57.52099379797, 53.8102740319414, 50.0994534129868, 
    46.3885581116054, 42.6776061726049, 38.966610469454, 35.2555804613682, 
    31.5445232840217, 27.8334444519932, 24.122348326088, 20.4112384335678, 
    16.7001176938427, 12.9889885820881, 9.27785325150787, 5.56671362791358, 
    1.85557148599325, -1.85557148599325, -5.56671362791358, 
    -9.27785325150787, -12.9889885820881, -16.7001176938427, 
    -20.4112384335678, -24.122348326088, -27.8334444519932, 
    -31.5445232840217, -35.2555804613682, -38.966610469454, 
    -42.6776061726049, -46.3885581116054, -50.0994534129868, 
    -53.8102740319414, -57.52099379797, -61.2315731880771, -64.9419494887575, 
    -68.6520167895175, -72.3615810293448, -76.0702444625451, 
    -79.7770456548256, -83.4789366693172, -87.1590945558629 ;

lev = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 ;

time = 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 ;