Research Topics

The main goal of my research is to better understand the role of clouds in the Earth climate system through high-resolution cloud modeling. The foci of modeling activities include microphysics processes, cloud mixing and entrainment, life-cycle of boundary layer clouds, drizzle, turbulence, shallow and deep convection, interactions of clouds with radiation and with atmospheric aerosol.

I have been interested in clouds and numerical modeling of clouds ever since my undergraduate and graduate student years at Moscow Institute of Physics and Technology in late 1980s, and my subsequent employment at the Central Aerological Observatory in Moscow. There, I got my first very valuable experience in cloud modeling. I have developed a numerical model of aircraft dry-ice seeding of orographic clouds applying the explicit or bin microphysics to model processes in artificially seeded clouds. I also developed my first 3-D cloud-resolving model with bulk microphysics.

During my Ph.D. studies at the University of Oklahoma, I developed one of the first Large-Eddy Simulation (LES) models with explicit/bin microphysics and applied it to study the evolution of drizzling marine stratocumulus clouds. Using the LES results, I developed a bulk microphysics parameterization for LES models. The expression for cloud water autoconversion-to-drizzle rate has been used in several regional models and even in a couple of General Circulation Models (GCMs).

After obtaining my Ph.D. degree in 1997, I redesigned my LES model to handle deep convective clouds and made it suitable to run on massively parallel computers. The new cloud-resolving model (CRM) named System for Atmospheric Modeling, or SAM, has been applied to various interesting convection problems, such as, for example, self similarity of deep convection. The easy-to-use-model philosophy and ability to run on hundreds of processors have made SAM quite popular among cloud modelers; in fact, SAM has been used by more than a dozen scientists in the United States and Canada and helped to generate quite a few publications. Here is an incomplete list of organizations whose scientists have been using SAM in their research: Colorado State University, Pacific Northwest National Laboratory, University of Washington, Harvard University, University of Miami, University of British Columbia, University of Oklahoma, NOAA, NASA Langley, University of Hawaii, University of Wisconsin, Scripps Institution of Oceanography.

I also have strong research interests in the area of climate modeling. Several years ago, I put together the first realistic GCM with cloud-resolving model in place of conventional sub-grid scale parameterizations. The resultent model has become known as the Multiscale Modeling Framework (MMF). The prototype MMF has thousands of CRM models running simultaneously; in each GCM grid cell, the CRM (a.k.a. ‘super-parameterization’) simulates the thermodynamic tendencies due to precipitating clouds evolving in response to GCM large-scale forcing and radiation heating rates computed independently in each CRM column. As the result, the MMF has much higher computational cost than a conventional GCM; however, since the ratio of the time that the MMF spends computing to the time spent for inter processor communication is much higher than the one for conventional GCMs, the MMF is vastly more scalable on parallel computers. In fact, it was demonstrated to run on 1024 processors of IBM SP supercomputer with 95% parallel efficiency. Due to its computational cost, the MMF is primerely used to conduct relatively short, 5-10-20 year long present climate simulations using the sea surface temperatures (SSTs), climatological or observed over the same period. The MMF has simulated many observed features of the modern climate rather well. For example, it has simulated a very robust and realistic Madden-Julian Oscillation (MJO) which has been quite a challanging phenomenon for most conventional GCMs to simulate. MMF has also been used to conduct idealized climate sensitivity experiments when the control simulations of the current climate are compared to the simulations of climate with prescribed warmer SSTs. As the next step, the MMF will be coupled with an ocean model to simulate future climate change.