Figure 1
Representative fields from the evolution of the baroclinically-unstable wave at t = 9 days. The surface pressure (top) and temperature on the 850 mb surface (middle) are directly comparable to other model results in Jablonowski and Williamson (2006). The idealized passive tracer on the 500 mb surface (bottom) is initially zero in the sunlit regions of the globe; it illustrates the representation of three-dimensional transport in NEPTUNE.
Figure 2
Representative fields from the evolution of the baroclinically-unstable wave at t = 18 days. The pressure (top) and temperature (middle) fields appear to be a mixture of wave-like and eddy-like disturbances. The tracer field (bottom) is undergoing vigorous chaotic stirring.
Figure 3
Comparison between the TLM potential temperature and nonlinear perturbation in NEPTUNE. The TLM is initialized with a perturbation equal to 1/8th the difference of the JW baroclinic test case at days 10 and 11, using all NEPTUNE prognostic variables (density, potential temperature, velocity, and tracer). Panels (a)–(c) show, respectively, the TLM field, Δ, the error with respect to the evolution of the NEPTUNE perturbation, Δ+ – Δ, and the nonlinearity metric, Δ+ – Δ–, at T = 9 hr integration, linearized around the JW test case starting at t = 9 day. Panels (d)–(f) show the evolution after T = 24 hr integration.
Figure 4
The evolution of a meridional velocity perturbation, as in Figure 3.
Figure 5
Time series of the root-mean-square (RMS) perturbation solution metrics for (a) potential temperature and (b) meridional velocity. The area-average RMS of the NEPTUNE perturbation solution Δ+ (solid black) and TLM solution Δ nearly overlap throughout the 72-hr integration time. The nonlinearity of the NEPTUNE solution Δ+ – Δ– (solid red) grows at about twice the rate of the error in the TLM solution Δ+ – Δ (dashed red).
Figure 6
The evolution the adjoint sensitivities on the 850 mb surface for a measurement of potential temperature at T = 72 hr (60∞N, 260∞E, grey circle repeated in each panel). Panels (a)–(c) show the adjoint potential temperature sensitivity, which is predominantly advected backwards towards the northwest along the path of the mean flow at (a) T = 70 hr and (b) T = 60 hr. The complex pattern at (c) T = 48 hr exhibits the smaller scales associated with the deformations of the background flow. Panels (d)–(f) show the adjoint sensitivity of the meridional velocity, which is undergoing a geostrophic adjustment with the adjoint potential temperature.