THE DETERMINATION OF CLOUD PRESSURES FROM ROTATIONAL RAMAN-SCATTERINGIN SATELLITE BACKSCATTER ULTRAVIOLET MEASUREMENTS

We have retrieved cloud pressures with the Nimbus 7 solar backscatter ultraviolet spectrometer and total ozone mapping spectrometer by utili zing properties of rotational Raman scattering. The retrieved cloud pr essures are compared with coincident cloud pressures derived from the temperature humidity infrared sounder, as well as climatological cloud pressures from the International Satellite Cloud Climatology Project. Results show good agreement between cloud pressures measured using ul traviolet and infrared techniques, although a small bias is present. T he bias in cloud pressures is likely due in part to different radiativ e properties of clouds at ultraviolet and infrared wavelengths. The ul traviolet measurements described here are sensitive to cloud optical t hickness, while infrared measurements are sensitive to cloud top tempe rature. Ultraviolet cloud pressure measurements combined with measurem ents from other spectral regions may therefore provide information abo ut cloud type. Cloud pressures measured by means of ultraviolet scatte ring properties will be more appropriate for use in satellite backscat ter ultraviolet ozone retrieval algorithms. We suggest ways in which f uture ultraviolet remote sounding instruments may be designed to more optimally measure cloud pressure.