THE BLUE/VIOLET SPECTRAL RANGE IS OF GREAT UTILITY IN SATELLITE MEASUREMENTS OF TRACE GASES BUT IT IS ALSO A REGION IN WHICH COMPLETE REFERENCE SPECTRA ARE NOT AVAILABLE FOR TWO CRUCIAL ABSORBERS: WATER VAPOR AND THE O2-O2 COLLISION COMPLEX. RELIABLE REFERENCE SPECTRA ARE NEEDED NOT JUST BECAUSE BOTH GASES PROVIDE MEANINGFUL INFORMATION IN THEIR OWN RIGHT BUT ALSO BECAUSE THEIR ABSORPTION OVERLAPS WITH THAT OF OTHER TRACE GASES SUCH AS NITROGEN DIOXIDE (NO2) IODINE MONOXIDE (IO) AND GLYOXAL (CHOCHO). IMPERFECT REFERENCES CAN BIAS RETRIEVALS OF SATELLITE INSTRUMENTS SUCH AS THE OZONE MONITORING INSTRUMENT (OMI) TROPOSPHERIC MONITORING INSTRUMENT (TROPOMI) AND TROPHOSPHERIC EMISSIONS: MONITORING OF POLLUTION (TEMPO). I PROPOSE TO OPTIMIZE THE UNIVERSITY OF COLORADO LIGHT-EMITTING DIODE CAVITY-ENHANCED DIFFERENTIAL OPTICAL ABSORPTION SPECTROSCOPY INSTRUMENT (CU LED-CE-DOAS) TO MEASURE THE ABSORPTION CROSS SECTIONS OF WATER AND O2-O2 AT BLUE/VIOLET WAVELENGTHS. LED-CEDOAS EXPLOITS THE UNIQUE SENSITIVITY AND BENEFITS OF CAVITY-ENHANCED ABSORPTION SPECTROSCOPY (CEAS) TO CREATE THE LONG EFFECTIVE SAMPLE PATH LENGTHS (UP TO ~20 KM) NECESSARY TO REALIZE LARGE SLANT COLUMN DENSITIES (SCD) UNDER WELL-CONTROLLED LABORATORY CONDITIONS AND ALLOW ACCESS TO WEAK ABSORPTION LINES THAT CONTRIBUTE SIGNIFICANT ABSORPTION IN FIELD SPECTRA. IN ADDITION THE BROADBAND LIGHT SOURCE ENABLES SIMULTANEOUS MEASUREMENT OF BAND SHAPES. THE MEASUREMENTS OF WATER VAPOR AND O2-O2 COLLISION-INDUCED ABSORPTION (CIA) WILL BE USED TO REFINE THE REPRESENTATION OF BOTH MOLECULES IN THE HIGH RESOLUTION TRANSMISSION MOLECULAR ABSORPTION DATABASE (HITRAN) AND THE HIGH TEMPERATURE COMPANION DATABASE HITEMP. IMPROVED REFERENCE SPECTRA WILL BENEFIT DOAS RETRIEVALS FOR SATELLITE SURFACE AND AIRCRAFT REMOTE SENSING INSTRUMENTS.