Climate Module

This calculates the global surface temperature change, considering the energy balance due to radiative forcing in four surface boxes (north, south, land, ocean), and the slow uptake of heat by a multilayer upwelling-diffusion ocean.
  • Link to Source Code

    Interactions

  • Affected by: Radiative Forcing, Load-Data
  • Affects: Sealevel, Regional Climate, Carbon (biogeochemical feedbacks), Mitigation (if stabilising temperature) Costs (experimental), Global Temperature Plot

    Adjustable parameters

  • Temperature baseline year (only affects plot and "stabilise temperature" control).
  • UDEB Climate model parameters (see red items below)
  • GCM-fit menu adjusts parameters together (as in IPCCTAR WG1 Apx9.1)

    How it works

    This is an efficient java implementation of the Wigley/Raper Upwelling-Diffusion Energy Balance (UDEB) model which was used to make many of the the smooth-curve plots in the IPCC-TAR WG1. Parameters are tuned to fit seven different GCM predictions, as described in IPCCTAR-WG1-Appx 9.1. The system of heat fluxes is resolved using an efficient eigenvector calculation method.

    Features of UDEB model

    (Adjustable parameters in red)
  • Four surface boxes: north & south, land & ocean
  • In each box, the "lambda" values for calculating heat flux to space are derived from the prescribed equilibrium climate sensitivity and land-ocean temperature ratio parameters.
  • Surface fluxes depend on land-ocean and north-south conductivities (these are fairly arbitrary, but have little impact on the global average temperature)
  • Radiative forcing of aerosols and short-lived gases is unevenly distributed between boxes (e.g. most of the sulphate aerosol cooling is in the north-land box)
  • Two 1-D Upwelling-Diffusion Oceans (north and south), connected only at surface:
  • Fixed vertical diffusivity between layers (unlike carbon model).
  • A high latitude downwelling "pipe" (rather than a separate box), for whose water temperature is a fixed fraction of the average temperature (polar sink temperature ratio parameter).
  • A "sea-ice" parameter adjusts the water/air temperature ratio.
  • The lag of the surface ocean warming also depends on the mixed layer depth.
  • The rate of this downwelling/upwelling is reduced with temperature to account for changing thermohaline circulation (parameter to be added).

    See also:

  • Efficient Eigenvector Calculation Method
  • Global Temperature Plot, Discussion
  • Correspondence with IPCC predictions
  • /IPCC-TAR-WG1 appendix 9.1
  • Raper et al 2001 and references therein.
  • An IPCC technical paper (1997) describes an earlier version of this model.

    Future development

    The next step from here, might be to investigate the possibility to develop an interactive java version of intermediate complexity models. The simplest of these is the Bern zonally averaged model with the 2.5D Ocean.