New ground-based measurements of NO3 absorption in the band near 662 nm were carried out using the moon as a light source during sunrise on July 1, 1988. As the sun rose, the observed slant column abundance of atmospheric NO3 decreased systematically. This time-dependent decrease is expected, due to the progression of the solar terminator down through the atmosphere, and provides a basis for inferring the nighttime vertical profile of NO3. This approach represents a new means of measuring the vertical profile of stratospheric species whose distributions change rapidly at sunrise. The profile inferred from the time-dependent NO3 decrease is sensitive to the NO3 absorption cross section and the adopted photolysis rate, and these sensitivities are investigated. The inferred vertical profile on July 1, 1988, is in excellent agreement with theoretical predictions in the altitude range from about 20 to 33 km. At higher levels near 40 km, the NO3 abundance is found to be quite sensitive to the adopted rate constant for thermal decomposition of N2O5. The profile inferred from these measurements suggests a relatively slow rate of N2O5 thermal decomposition in this region. ¿ American Geophysical Union 1990