Charged Particle Mass and Numberhttps://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_table4-2-4-2.shtmlPLSMDENParticle Number Densitym-3ELCDENElectron Densitym-3PROTDENProton Densitym-3IONDENIon Densitym-3VTECVertical Electron Contentm-2ABSFRQHF Absorption FrequencyHzABSRBHF AbsorptiondBSPRDFSpread FmHPRIMFh'FmCRTFRQCritical FrequencyHzSCINTScintillationNumeric