Confronting Low-cloud Simulations with Observations
Geography and Atmospheric Science
University of Kansas
TCS Building 240
Low stratiform clouds in the tropics and subtropics are a substantial cooling term in the global climate system but remain a stubborn challenge for Earth System Models (ESMs). Low clouds are represented in ESMs using parameterizations that are often based on output from high-resolution process models. But how reliable are the cloud properties and processes produced by these models? Process models are typically configured using forcing that may exhibit substantial uncertainty and be only loosely constrained by observations.
We seek an improved understanding of cloud processes from imperfect models run with uncertain estimates of environmental forcing and compared against incomplete and uncertain observations of cloud properties. I present three examples of using innovative datasets or methodological approaches to confront models with observations. Specific applications include 1) a large-eddy simulation study of a highly variable cloud transition case over the Department of Energy Southern Great Plains supersite sampled from a new radar suite; 2) using a mesoscale simulation of marine boundary-layer clouds together with ship-based observations to evaluate microphysical parameterizations; and 3) a model intercomparison study of Doppler radar spectra from boundary-layer cloud sampled from Doppler cloud radar over the eastern North Atlantic. These approaches argue for hybrid modeling/observational pathways as one way to provide additional value to observations.
Growing up in Oklahoma, Dr. Mechem, was interested early-on in severe weather, computers, and astronomy. This led him first to the University of Oklahoma and then to the University of Washington, where his dissertation research was on mesoscale convective systems over the western tropical Pacific. He is currently a Professor at the University of Kansas.