Advancing Understanding of Deep Convective Anvil Clouds

Deep convective cloud

deep convective cloud

Deep convective clouds (e.g., cumulonimbus clouds) are associated with severe storms, which can transport ice and supercooled large droplets into the higher levels of the atmosphere, frequently reaching an altitude of 10 km (33,000 feet), and sometimes much higher.

Source: NOAA Source

shields, largely comprising stratiform anvils, have significant impacts on atmospheric radiation and water budgets, and thus it is important to understand the drivers of their fractional coverage. In this project, we analyze the processes that govern the sizes of convective cloud shields using both Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) observations (collected during the GOAmazon field campaign) and Weather Research and Forecasting (WRF) model simulations of observed convective systems at the GOAmazon and SGP sites.

Our preliminary observational case study analyses using GOAmazon-geolocated infrared (IR)

infrared spectroscopy

Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection.

Source: Science Direct Source

satellite data for quantifying cloud shield sizes, radar wind profiler (RWP) vertical velocity retrievals and new RWP latent heating retrievals suggest that latent heat release in convective towers may be more strongly related to the subsequent change in the cloud shield size compared to other conventional parameters (e.g., the vertical convergence of convective mass flux)

flux

The amount of some type of particle or energy crossing a unit area per unit time.

Source: NRC Library Source

. There are a number of processes that influence cloud shield size that can be further quantified using model output, although our early analyses of WRF idealized mesoscale convective system

mesoscale convective system (MCS)

A collection of thunderstorms that act as a system. An MCS can spread across an entire state and may appear as a solid line, a broken line, or a cluster of cells that can last more than 12 hours.

Source: NOAA Source

(MCS) simulations reveal similar findings.

We will perform an expanded observational study of all convective systems that pass the GOAmazon RWP site with a focus on the relationship between vertical velocity profiles, latent heating profiles, environmental information, and IR-identified cloud shields. We demonstrate that despite the limited convective system-sampling capabilities of the upward-looking “pencil” RWP instrument, robust statistical results on the aforementioned relationships can still be achieved. Additionally, we will analyze a number of idealized and real-atmosphere MCS large eddy simulations at GOAmazon and SGP, with selected model simulations (e.g., those that compare favorably to observations of convective core structures, vertical velocities, etc.) being used to complement ARM observations to constrain and inform our conceptual understanding of what processes (e.g., mass fluxes, precipitation, wind shear, evaporation near edges of the cloud shield, latent heating) are the dominant sources and sinks of the cloud shield size on hourly timescales.

Our project integrates researchers from multiple institutions, with investigators at the National Center for Atmospheric Research (NCAR) providing the WRF simulations, and investigators at the NASA Goddard Space Flight Center (GSFC) helping to adapt the NASA Convective Stratiform Heating (CSH) satellite latent heating algorithm to ground-based DOE/ARM observations. Overall, our study, aligned with the DOE Atmospheric System Research (ASR) mission and “convective processes” theme, will inform our understanding of how the environment and convective towers themselves influence system sizes, which in turn will inform our conceptual understanding of how convection-driven high clouds may vary on longer (climate) time scales.