The evolution of anvil cirrus in the Tropical Western Pacific using satellite and ground-based observations and model simulations

In this study, the anvil cirrus evolution in the tropical western pacific is unveiled in three steps with ground-based and satellite measurements and model simulations.; First, Millimeter Cloud Radar (MMCR) observation at Tropical Western Pacific (TWP) sites during the Atmospheric Radiation Measurement (ARM) program and the Geosynchronous Meteorological Satellite-derived 12-hour Lagrangian back tracking data are combined to study the deep convection association of tropical cirrus that are common in the 10-15km layer of the tropical troposphere in the western Pacific. Using a data record of 1 year, the analysis shows that 47% of the cirrus observed over Manus can be traced to a deep convective source within the past 12 hours whereas just 16% of the cirrus observed over Nauru appear to have a convective source within the previous 12 hours.; Second, an innovative algorithm using MMCR three Doppler moments is developed to retrieve cirrus microphysical properties and the mean air vertical motion and their errors based on the fact that the observed Doppler spectrum results from the convolution of a quiet air radar reflectivity spectrum with the turbulence probability density function. The estimated algorithm errors are on the order of 35%, 85%, +/-20cm/s for mass-mean particle size, IWC (Ice Water Content), and sample volume-mean air motion, respectively. Algorithm validation with in situ data demonstrates that the algorithm can determine the cloud microphysical properties and air mean vertical velocity within the predicted theoretical error bounds.; Finally, by combining the satellite Lagrangian trajectories, ground-based MMCR observations, and the retrieval dataset at ARM TWP sites, the tropical anvil clouds' evolution from their convective origins are determined both physically and dynamically. An anvil cloud can last for more than 12 hours while its IWP decays with time. Strong updrafts and downdrafts are found in the cloud top and their magnitudes generally decrease as the anvils age. The UULES (University of Utah Large Eddy Simulation) model was used to produce two sets of dissipating anvil simulations. The first set of anvil simulations (with and without radiation) shows that the cloud radiative effects can produce updrafts and downdrafts in the cloud, especially at the cloud top. The net effect of radiation lifts the cloud layer and spreads it horizontally. The second set of anvil simulations with the larger IWP and larger relative humidity shows the influence of the cloud properties and the moist level in the environment on the anvil evolution.