• 6.2.1.1 Introduction
• 6.2.1.2 Key subroutines, parameters and files
• 6.2.1.3 GAD Diagnostics
• 6.2.1.4 Experiments and tutorials that use GAD

6.2.1 Generic Advection/Diffusion

The generic_advdiff package contains high-level subroutines to solve the advection-diffusion equation of any tracer, either active (potential temperature, salinity or water vapor) or passive (see pkg/ptracers). (see also sections 2.16 to 2.19).

6.2.1.1 Introduction

Many different advection schemes are available: the standard centered second order, centered fourth order and upwind biased third order schemes are known as linear methods and require some stable time-stepping method such as Adams-Bashforth. Alternatives such as flux-limited schemes are stable in the forward sense and are best combined with the multi-dimensional method provided in gad_advection.

6.2.1.2 Key subroutines, parameters and files

• GAD_CALC_RHS calculates all fluxes at time level ``n'' and is used for the standard linear schemes. This must be used in conjuction with Adams-Bashforth time stepping. Diffusive and parameterized fluxes are always calculated here.

• GAD_ADVECTION calculates just the advective fluxes using the non-linear schemes and can not be used in conjuction with Adams-Bashforth time stepping.

6.2.1.3 GAD Diagnostics

------------------------------------------------------------------------
<-Name->|Levs|<-parsing code->|<--  Units   -->|<- Tile (max=80c) 
------------------------------------------------------------------------
ADVr_TH | 15 |WM      LR      |degC.m^3/s      |Vertical   Advective Flux of Pot.Temperature
ADVx_TH | 15 |UU   087MR      |degC.m^3/s      |Zonal      Advective Flux of Pot.Temperature
ADVy_TH | 15 |VV   086MR      |degC.m^3/s      |Meridional Advective Flux of Pot.Temperature
DFrE_TH | 15 |WM      LR      |degC.m^3/s      |Vertical Diffusive Flux of Pot.Temperature (Explicit part)
DIFx_TH | 15 |UU   090MR      |degC.m^3/s      |Zonal      Diffusive Flux of Pot.Temperature
DIFy_TH | 15 |VV   089MR      |degC.m^3/s      |Meridional Diffusive Flux of Pot.Temperature
DFrI_TH | 15 |WM      LR      |degC.m^3/s      |Vertical Diffusive Flux of Pot.Temperature (Implicit part)
ADVr_SLT| 15 |WM      LR      |psu.m^3/s       |Vertical   Advective Flux of Salinity
ADVx_SLT| 15 |UU   094MR      |psu.m^3/s       |Zonal      Advective Flux of Salinity
ADVy_SLT| 15 |VV   093MR      |psu.m^3/s       |Meridional Advective Flux of Salinity
DFrE_SLT| 15 |WM      LR      |psu.m^3/s       |Vertical Diffusive Flux of Salinity    (Explicit part)
DIFx_SLT| 15 |UU   097MR      |psu.m^3/s       |Zonal      Diffusive Flux of Salinity
DIFy_SLT| 15 |VV   096MR      |psu.m^3/s       |Meridional Diffusive Flux of Salinity
DFrI_SLT| 15 |WM      LR      |psu.m^3/s       |Vertical Diffusive Flux of Salinity    (Implicit part)

6.2.1.4 Experiments and tutorials that use GAD

• Offline tutorial, in tutorial_offline verification directory, described in section 3.20
• Baroclinic gyre experiment, in tutorial_baroclinic_gyre verification directory, described in section 3.10
• Tracer Sensitivity tutorial, in tutorial_tracer_adjsens verification directory, described in section 3.19

Copyright © 2006 Massachusetts Institute of Technology

Last update 2011-01-09