Research:

Research Interests:

Deep cumulonimbus clouds form the upward branch of large scale thermal circulations in the tropics. These circulations, which include the global Hadley-Walker circulation and regional monsoon flows, are of crucial importance not only to the tropics, but to mid-latitude weather and climate as well. However, the mechanisms which control the strength and location of these circulations are imperfectly understood. Some of the biggest uncertainties are related to how cumulus convection is controlled, and to the structure and vertical transfer characteristics of this convection. The way in which water vapor is vertically redistributed is an issue of particular concern.

Traveling tropical disturbances such as the Madden-Julian oscillation, Kelvin waves, mixed Rossby-gravity waves, easterly waves, and tropical storms are also very sensitive to cumulus convection.

My current interests are in unraveling how deep atmospheric convection interacts with tropical circulations and how these circulations work as a result. The TCS-08 project (see below) will provide insight into this process in the context of developing and intensifying tropical storms. In addition, we are using simple analytical models, numerical models, including cumulus ensemble models, and a simplified large-scale equatorial beta plane model, to test ideas about how convection works in large scale tropical circulations. Ultimately, knowledge gained from modeling, theory, and field observations should lead to better representations of convection in numerical models, and hence better weather and climate predictions. To this end we are also studying how convection works in NCEP's Global Forecast System (GFS) model.

TPARC/TCS-08

In August and September of 2008 we will be participating in TCS-08, a project to study the formation and structure change of western Pacific typhoons. We will be based in Guam with excusions to Okinawa and Japan as needed to follow the evolution of these typhoons. Two aircraft will be based in Guam; the NRL P-3 aircraft with the ELDORA Doppler radar, Doppler lidar, and dropsondes, as well as an Air Force C-130 "hurricane hunter" deploying dropsondes. Other aircraft in this project are the Taiwanese Dotstar jet and the German DLR Falcon. The latter two aircraft, with help from the P-3 and the C-130, will study the extratropical transition of west Pacific typhoons.

EPIC:

EPIC was a program consisting of enhanced monitoring, modeling, and intensive process studies designed to help us understand the coupled ocean-atmosphere system of the east Pacific. EPIC was a part of the U. S. CLIVAR Program with connections to other national programs in Mexico, Central America, and South America. EPIC2001 was a process study proposed under the umbrella of EPIC for a 6 week period in September-October 2001 with the purpose of studying the east Pacific intertropical convergence zone, the associated cross-equatorial inflow, and the east Pacific warm pool. It also contained an exploratory study of the ocean and atmosphere in the east Pacific stratus region south of the equator. Read my personal view of EPIC's accomplishments.

Weak Temperature Gradient Cumulus Ensemble Model

The source code for the latest version of our weak temperature gradient cumulus ensemble model is available here. It is in the form of a gzipped tar file. The model is coded in the C language, and it needs a version of MPI such as LAM/MPI to run, as well as the Candis system.

Recent Papers and Preprints: