https://www.nco.ncep.noaa.gov/pmb/docs/on388/table3.html Ground or water surface SFC Cloud base level CBL Cloud top level CTL Level of 0 deg (C) isotherm 0DEG Level of adiabatic condensation lifted from the surface ADCL Maximum wind level MWSL Tropopause TRO Nominal top of atmosphere NTAT Sea bottom SEAB Isothermal level (temperature in 1/100 K in octets 11 and 12) TMPL Highest tropospheric freezing level HTFL Grid scale cloud bottom level GCBL Grid scale cloud top level GCTL Boundary layer cloud bottom level BCBL Boundary layer cloud top level BCTL Boundary layer cloud layer BCY Low cloud bottom level LCBL Low cloud top level LCTL Low cloud layer LCY Cloud ceiling CEIL Cumulonimbus Base (m) CBB m Cumulonimbus Top (m) CBT m Planetary Boundary Layer (derived from Richardson number) PBLRI Middle cloud bottom level MCBL Middle cloud top level MCTL Middle cloud layer MCY High cloud bottom level HCBL High cloud top level HCTL High cloud layer HCY Ocean Isotherm Level (1/10 deg C) OITL .1 degC Layer between two depths below ocean surface depth of upper surface (dam) (octet 11) depth of lower surface (dam) (octet 12) OLYR Bottom of Ocean Mixed Layer (m) OBML m Bottom of Ocean Isothermal Layer (m) OBIL m Layer Ocean Surface and 26C Ocean Isothermal Level S26CY Ocean Mixed Layer OMXL Ordered Sequence of Data OSEQD Convective cloud bottom level CCBL Convective cloud top level CCTL Convective cloud layer CCY Lowest level of the wet bulb zero LLTW Maximum equivalent potential temperature level MTHE Equilibrium level EHLT Shallow convective cloud bottom level SCBL Shallow convective cloud top level SCTL Deep convective cloud bottom level DCBL Deep convective cloud top level DCTL Lowest bottom level of supercooled liquid water layer LBLSW Highest top level of supercooled liquid water layer HTLSW