Factors Controlling the Formation and Evolution of Subtropical Cumulonimbus Anvils During CRYSTAL-FACE
Fridlind, A.M., Ackerman, A.S., and Jensen, E.J., NASA Ames Research Center
Fourteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting
Cumulonimbus systems have been hypothesized to play an important role in global climate sensitivity and their impact on moisture levels in the tropical tropopause layer may also modulate stratospheric water vapor concentrations. But the properties of cumulonimbus anvils and the factors controlling them remain poorly understood. Here we use extensive in situ and remote sensing data from the CRYSTAL-FACE field experiment to determine the factors controlling initial anvil properties and subsequent anvil evolution. Using a 3-dimensional large-eddy simulation with size-resolved distributions of aerosols, cloud droplets, and ice particles, we simulate anvil formation and evolution on seven days during the experiment (July 3, 11, 16, 19, 21, 28, and 29). In previous work, we have found that the number and size distribution of the observed anvil crystals is strongly dependent upon entrainment of midtropospheric aerosols into updraft cores. In this work, we focus on the response of anvil properties and evolution to the observed variability of five factors: aerosol profiles, relative humidity profiles, wind shear profiles, updraft strength and frequency, and radiative fluxes. Initial sensitivity tests indicate that aerosol profiles, shear, and updraft strength together control initial anvil properties, whereas initial upper-level relative humidity, shear, and radiative fluxes are expected to control anvil evolution.
Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).
