Thursday, 2 May 2002: 12:00 PM
Vertical mass, momentum, moisture, and heat fluxes in hurricanes above 10 km during CAMEX-3 and CAMEX-4
The third and fourth NASA Convection and Moisture Experiments (CAMEX-3 and CAMEX-4) during the Atlantic
hurricane seasons of 1998 and 2001, respectively, have yielded comprehensive multi-aircraft datasets
using both remote and in-situ instrumentation. Among these are high-frequency in-situ measurements
of vertical wind, horizontal wind, temperature, and water vapor, made from NASA's DC-8 aircraft in
the upper portions of the hurricane (typically above 10 km).
Wind and temperature measurements were made at 20 hz by the NASA/Ames Meteorological Measurement
System, while water vapor was measured at 1 hz by the NASA/JPL Laser Hygrometer.
Fluxes of heat, momentum, and moisture at these levels are important, since
modeling studies have shown that ice processes, which are dominant at temperatures below -40C (where
the DC-8 flies) are important for hurricane intensification. Also, there are indications from satellite
studies that latent heat release at DC-8 levels is significant, perhaps a third as large as the heat release in the mid-troposphere. Preliminary results show that typical
updrafts in the eyewall region are
comparable to or higher than previous observations of tropical convection, with several instances of updraft
magnitudes of 15 meters per second (the maximum observed was 21 meters per second). They also show
significant supersaturations (10-20% or more) in the updrafts, which would enhance the latent heat release
at the upper levels of the hurricane. This paper will examine the magnitude and distribution of small
and mesoscale vertical fluxes of mass, momentum, moisture, and heat. The goal is to examine the role
of these fluxes in the overall budgets of the respective quantities in the upper portions of the hurricane.
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