Abstract
Abstract. A critical stage in the development of our ability to model and project climate change occurred in the late 1950s–early 1960s when the first primitive-equation atmospheric general circulation models (AGCMs) were created. A rather idiosyncratic project to develop an AGCM was conducted virtually alone by Cecil E. Leith starting near the end of the 1950s. The Leith atmospheric model (LAM) appears to have been the first primitive-equation AGCM with a hydrological cycle and the first with a vertical resolution extending above the tropopause. It was certainly the first AGCM with a diurnal cycle, the first with prognostic clouds, and the first to be used as the basis for computer animations of the results. The LAM project was abandoned in approximately 1965, and it left almost no trace in the journal literature. Remarkably, the recent internet posting of a half-century-old computer animation of LAM-simulated fields represents the first significant “publication” of results from this model. This paper summarizes what is known about the history of the LAM based on the limited published articles and reports as well as transcripts of interviews with Leith and others conducted in the 1990s and later.
Highlights
The earliest effort developing a global primitive-equation model was led by Joseph Smagorinsky at the General Circulation Research Section of the US National Weather Service starting in 1956 (Smagorinsky, 1983)
This produced classic papers on the original versions of the model (Smagorinsky, 1963; Smagorinsky et al, 1965) and was the basis for the later development of many influential climate models at the GFDL (Edwards, 2000). Another pioneering modeling effort was led by Akio Arakawa and Yale Mintz at the University of California Los Angeles (UCLA) who began work on a two-level primitive-equation global model in 1961 with a version including a hydrological cycle completed in the middle of 1963
Around 1958 Leith began to consider the development of a global atmospheric circulation model as a major activity, and in 1960 he produced the first version of the Leith atmospheric model (LAM)
Summary
The numerical modeling of the global climate is an enterprise employing many hundreds of scientists and support staff working at dozens of institutions, and the results of contemporary global climate models inform some of the world’s most consequential public policy decisions. The earliest effort developing a global primitive-equation model was led by Joseph Smagorinsky at the General Circulation Research Section of the US National Weather Service (the forerunner of today’s Geophysical Fluid Dynamics Laboratory, GFDL) starting in 1956 (Smagorinsky, 1983) This produced classic papers on the original versions of the model (Smagorinsky, 1963; Smagorinsky et al, 1965) and was the basis for the later development of many influential climate models at the GFDL (Edwards, 2000). It seems he never pursued the LAM model at NCAR, and while he presumably encouraged the climate model development effort at NCAR, he was never directly involved
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