The response of an equatorial ocean to simple wind stress patterns: I. Model formulation and analytic results

A simple model is developed to study the wind-driven equatorial ocean circulation. It is a time dependent, primitive equation, beta plane model that is two-dimensional in the horizontal. The vertical structure consists of two layers above the thermocline with the same constant density. The ocean below the thermocline is taken to be of a higher constant density and to be approximately at rest. The surface layer is of constant depth and is acted upon directly by the wind...

The response of an equatorial ocean to simple wind stress patterns: II. Numerical results

The model developed by Cane (1978) is used to study the wind-driven circulation in an equatorial ocean.· Simple wind stress patterns are imposed and the model evolution and eventual steady state are calculated· numerically. Both linear and fully nonlinear responses are discussed; dynamical arguments are presented to account for the principal features...

On topographic pressure drag in a zonal channel

The effect of bottom topography H on the barotropic transport in a periodic zonal channel is studied. An asymptotic approximation is found for the zonal transport on an f-plane and a β-plane when all f/H isolines are blocked by the zonal walls. It is shown that to leading order, the zonal channel transport is independent of friction. In this it is similar to the Sverdrup transport in a basin. To leading order, the transport is proportional to the bottom topographic wavelength, and inversely proportional to the height of the topography and to R, the range of values of f/H that exists on both sides of the channel. For sufficiently high topography the transport varies inversely with the topographic height squared. The analytic results are verified by numerical experiments

The response of a linear baroclinic equatorial ocean to periodic forcing

This paper examines the response of the linear inviscid shallow water equations on a meridionally infinite but zonally bounded equatorial β-plane to periodic zonal forcings at a low frequency ω…

Forced baroclinic ocean motions. I. The linear equatorial unbounded case

A method is developed for calculating the response of an unbounded inviscid ocean to wind stress and thermal forcings. Although emphasis is on equatorial baroclinic motions, the mathematical technique is first illustrated in detail for the motions described by the similar but simpler barotropic vorticity equation. This serves to clarify the significance of the asymptotic approximations made for the baroclinic planetary modes...

Forced baroclinic ocean motions, III: The linear equatorial basin case

Previous work on the linear spin-up of an equatorial ocean is extended to include the specific effects of the north-south extent of the basin, thus allowing a detailed comparison of analytic spin-up theory with numerical calculations…

Forced baroclinic ocean motions: II. The linear equatorial bounded case

This paper extends the results of Cane and Sarachik (1976) to an ocean bounded by two meridians. A complete solution is obtained for the asymptotic linear inviscid response to wind stress and thermal forcings independent of longitude, switched on at t=0 and steady thereafter. The mathematics is greatly simplified by building on the results of the earlier paper. The form of the solution is relatively simple..

Exploring the Potential for Using ENSO Forecasts in the U.S. Corn Belt

Interannual climate variability poses the greatest risk that farmers face. Until recently, seasonal climate forecasts have been weak and therefore rarely observed by farmers in making management decisions. Farm management is generally based on long-term mean expectations of climate and crop responses to local edaphic conditions. Currently, significant progress is being made in the skill level of predictions of seasonal to interannual climate, primarily because of new understanding of the teleconnections between ocean circulation and atmospheric processes. The El Niño/Southern Oscillation (ENSO) refers to fluctuations in both sea-surface temperatures (SSTs) in the eastern equatorial Pacific and in sea-level pressures in the southern Pacific at a time scale of roughly 3 to 7 years. Using ocean circulation models, we are now able to forecast the SST anomaly up to a year in advance with an 80% level of accuracy (Latif et al., 1994). Thus, associated climate phenomena may be predicted with a high degree of skill using this tool. Given the strong relationship between crop growth and climate, this predictability carries significant implications for improved efficiency of agricultural production (Adams et al., 1995; Sonka et al., 1986). In some regions, the teleconnection between climate and ENSO has been well established. In others, however, the relationship is only now being elucidated. Thus, the spatial extent of the potential for use of ENSO forecasts is not well defined. We are developing a methodology that uses analysis of historical climate and crop data as well as models of crop growth and farm management to explore the extent of ENSO impacts and implications for using forecasts in agricultural management. Based on the few studies that have been done, there is indication of a significant link between ENSO and climate in the midwestern United States. Using reconstruction from white oak tree rings in Iowa going back to 1640, Cleveland and Duvick (1992) showed a strong correlation with the Southern Oscillation Index, one indicator of the ENSO phase. Handler (1984) used yield data from the major Corn Belt states going back to 1868 and a classification scheme ranking event intensity. He found a strong relationship, with El Niño years associated with positive maize yield anomalies and La Niña with negative anomalies. Our current work extends the analysis of the U.S. Corn Belt, with the objective of testing the potential for using long-range ENSO/climate forecasts to increase profit margins and decrease risk for maize farmers in the United States