Extended Abstract (292K)4C.8
Airborne lidar measurements of water vapor profiles in the hurricane environment
Richard A. Ferrare, NASA/LRC, Hampton, VA; and E. V. Browell, S. Ismail, S. Kooi, L. H. Brasseur, A. Notari, L. Petway, M. Clayton, M. J. Mahoney, J. B. Halverson, F. J. Schmidlin, T. N. Krishnamurti, E. Bensman, V. Brackett, and R. Herman
The Lidar Atmospheric Sensing Experiment (LASE) Differential Absorption Lidar (DIAL) system was used to remotely measure the distributions of water vapor, aerosols, and clouds throughout the troposphere during the recent NASA Convection and Moisture Experiments (CAMEX-3 and CAMEX-4). This lidar system was deployed on the NASA DC-8 aircraft and simultaneously measured high resolution cross-sections of water vapor distributions above and below the aircraft. LASE signals were vertically smoothed and horizontally averaged to obtain nominal water vapor profile resolutions of 330 m (vertical) by 20 km (horizontal) in the nadir direction and 1 km (vertical) by 40 km (horizontal) in the zenith direction. The aerosol/cloud scattering ratio profiles typically have horizontal and vertical resolutions of 200 m and 30 m, respectively. During CAMEX-4, relative humidity profiles were constructed using the LASE water vapor profiles and temperature profiles measured above and below the aircraft by the DC-8 Microwave Temperature Profiler (MTP).
During CAMEX-3, which was conducted over the Atlantic Ocean and Gulf of Mexico during August-September 1998, LASE made the first extensive measurements of moisture, aerosol, and cloud distributions over four hurricanes: Bonnie, Danielle, Earl, and Georges. These measurements were acquired under outflow cirrus decks, within the eye of the hurricanes, over the rainbands, above moisture inflow regions, and in the clear air regions ahead of the hurricanes. Similarly, LASE measured moisture profiles in the vicinity of Hurricanes Erin and Humberto, and Tropical Storm Gabrielle during CAMEX-4, which occurred in the same region during August-September 2001. The LASE water vapor measurements acquired in the vicinity of Hurricane Erin showed an order of magnitude variation in water vapor in mid-upper troposphere east of the storm and showed dry air present in a cold trough located off the east coast. LASE measured large water vapor variations near the center east of (what was then) Tropical Storm Gabrielle when this storm left the east coast of Florida. LASE measurements were particularly valuable in showing the presence of dry air between 7-11 km that inhibited the rapid redevelopment of this tropical storm as it left the Florida coast.
We shall present examples of water vapor and relative humidity profiles derived from the LASE measurements during these experiments, and show how these reveal the moisture fields associated with hurricanes. Comparisons of LASE water vapor profiles with dropsondes and radiosondes launched during these missions will also be presented.
Session 4C, HL2001/CAMEX-4
Tuesday, 30 April 2002, 8:30 AM-10:30 AM
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