Nimbus 3/ATS 3 Observations of the Evolution of Hurricane Camille

Abstract

Three periods within the life cycle of Hurricane Camille (1969) are examined with radiometric and camera measurements from Nimbus 3 and camera information from ATS 3 in conjunction with conventional information. These periods are the deepening phase, the interaction of Camille with mid-latitude westerlies, and the excessive rain-producing period when the cyclone was over the central Appalachians. Just prior to significant deepening, the Nimbus 3 Medium Resolution Infrared Radiometer (MRIR) window and water vapor channels showed a band of developing convection that extended to the cirrus level in the southeastern quadrant of the storm which originated from the ITCZ. Low-level wind fields were derived from conventional sources as well as from cumulus clouds tracked from a series of ATS 3 images. Within this band were low-level 30 kt winds that supplied Camille with strong inflow where the air passed over sea surface temperatures that were 1?3 standard deviations above normal. At the beginning of the rapid deepening the MRIR radiometer measurements indicated a rapid contraction of the central dense overcast and then an expansion as the maximum deepening rate occurred. Simultaneously, the increase in the MRIR equivalent blackbody temperatures (TBB) indicated the development of large-scale subsidence throughout the troposphere northwest of the center. When Camille weakened as it moved over the lower Mississippi Valley, the cyclone acted as a partial obstruction to the synoptic-scale flow and increased the subsidence west and north of the cyclone center as indicated by the increase in water vapor TBB and verified by three-dimensional trajectories. Increased cloud-top elevations, approaching the levels reached when Camille was an intense cyclone over the Gulf of Mexico, were estimated from the Nimbus 3 High Resolution Infrared Radiometer (HRIR) measurements on 20 August 1969, when Camille produced rains of major flood proportions near the east slopes of the Appalachians in central Virginia.