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Pavlos Kollias
,
Ieng Jo
, and
Bruce A. Albrecht

Abstract

Unprecedented high-resolution observations of mammatus from a profiling 94-GHz Doppler radar during the NASA Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment (CRYSTAL–FACE) are presented. Because of its high sensitivity and temporal and spatial resolution, the cloud radar used was able to resolve the fine structure of individual mammatus clouds and record significant vertical Doppler velocity perturbations (−6 to +1 m s−1). Strong perturbations of the Doppler velocity within the mammatus as it extends below the main cirrus cloud base are captured by the radar observations. Upward motions in the periphery of descending mammatus cores are documented. Areas of intense, small-scale turbulent mixing near the cirrus cloud base are identified using the Doppler spectrum width. Power spectra analysis of the mean Doppler velocity field supports the presence of gravity waves and the development of higher-frequency structures near the cirrus anvil base, where the mammatus clouds are observed. The observations provide strong evidence for dynamical forcing from coherent vertical motions 500 m above the cloud base contributing to the mammatus formation. The results are discussed in the context of suggested theories for mamma formation and morphology.

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Marcus van Lier-Walqui
,
Ann M. Fridlind
,
Andrew S. Ackerman
,
Scott Collis
,
Jonathan Helmus
,
Donald R. MacGorman
,
Kirk North
,
Pavlos Kollias
, and
Derek J. Posselt

Abstract

The representation of deep convection in general circulation models is in part informed by cloud-resolving models (CRMs) that function at higher spatial and temporal resolution; however, recent studies have shown that CRMs often fail at capturing the details of deep convection updrafts. With the goal of providing constraint on CRM simulation of deep convection updrafts, ground-based remote sensing observations are analyzed and statistically correlated for four deep convection events observed during the Midlatitude Continental Convective Clouds Experiment (MC3E). Since positive values of specific differential phase observed above the melting level are associated with deep convection updraft cells, so-called columns are analyzed using two scanning polarimetric radars in Oklahoma: the National Weather Service Vance WSR-88D (KVNX) and the Department of Energy C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar (C-SAPR). KVNX and C-SAPR volumes and columns are then statistically correlated with vertical winds retrieved via multi-Doppler wind analysis, lightning flash activity derived from the Oklahoma Lightning Mapping Array, and KVNX differential reflectivity . Results indicate strong correlations of volume above the melting level with updraft mass flux, lightning flash activity, and intense rainfall. Analysis of columns reveals signatures of changing updraft properties from one storm event to another as well as during event evolution. Comparison of to shows commonalities in information content of each, as well as potential problems with associated with observational artifacts.

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