Summary: A Tropical and Subtropical Land­Sea­Atmosphere Drought Oscillation Mechanism
DORIAN S. ABBOT
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
KERRY A. EMANUEL
Program in Atmospheres, Oceans, and Climate, Massachusetts Institute of Technology, Cambridge, Massachusetts
(Manuscript received 26 May 2006, in final form 14 December 2006)
ABSTRACT
A two-column atmospheric model on a land­sea interface is studied. The model has sophisticated con-
vection, cloud, and radiation schemes, a mixed layer ocean, and a bucket model to simulate land hydrology.
A self-sustained oscillation in soil moisture with a period on the order of months is found. This oscillation
is strongest when the model is run with parameters chosen to correspond to the arid subtropics. The effect
of changing model parameters on the oscillation is explored. The existence and qualitative behavior of the
oscillation are relatively robust to changes in model parameters.
1. Introduction
A positive feedback between soil moisture anomalies
and precipitation has been documented extensively in
regional and global climate models (e.g., Walker and
Rowntree 1977; Sud and Fennessy 1984; Zheng and
Eltahir 1998; Hong and Kalnay 2000; Oglesby and
Erickson 1989; Shukla and Mintz 1982). There is obser-

Source: Abbot, Dorian Schuyler - Department of Geophysical Sciences, University of Chicago
Emanuel, Kerry A. - Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology (MIT)

Collections: Geosciences