Gregory Elsaesser
NASA GISS, Columbia University

"New Process-Oriented Metrics for Guiding Convective Parameterization Development in the NASA GISS GCM"

Abstract: This talk will begin with an overview of recent development in the representation of clouds and convection in the NASA Goddard Institute for Space Studies (GISS) General Circulation Model (GCM). Further near-term improvements in the simulation of convection, coincident with decreases in regional top-of-the-atmosphere radiation biases, may occur with the development of an improved cloud tuning approach that will be briefly described; however, such improvements may be more minimal. Using a variety of new satellite-derived process-oriented metrics, I will instead show that further improvements in the simulation of some important features (e.g., diurnal cycle, the partitioning between convective and stratiform rainfall) are not likely to occur until aspects of the lifecycle of deep (and sometimes organized) convective systems are parameterized. The remainder of the talk will then focus on what processes and environments may govern the lifecycle of convective systems, with particular attention paid toward determining whether the large-scale state or local moisture and buoyancy state close to propagating convective systems is the dominant driver for determining convective system evolution and lifetime. Such knowledge is crucial for guiding our future GISS GCM convective parameterization efforts.

Biogrpahy: Dr. Gregory Elsaesser's research focuses on the use of satellite data to deduce properties of convection and the ambient mesoscale environment. He also develops satellite algorithms for the retrieval of and creation of rain and cloud property records. He has recently finished production of the Version-1 Multisensor Advanced Climatology of Liquid Water Path (MAC-LWP) record for improved cloud LWP observations in stratocumulus regimes, and developed an improved parameterization of ice in convective updrafts for use in the GISS Model E2 GCM.