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CableUserGuide_EndMatter
Code: While some cleaning up of the code has occurred for CABLE-2.0 relative to CABLE-1.4b, there are, no doubt, numerous instances where our proposed coding standards are not met. For example, a number of routines include hard-wired vegetation or soil type numbers. We have attempted to ‘comment’ these occurrences and intend to fix them for the next code release. If you spot other instances of poor code, please write a ticket on the trac system https://trac.nci.org.au/trac/cable/newticket), and suggest/test a fix.
Global, offline: This case may crash if the model build includes a –ftz –fpe0 option. This is under investigation.
Single-site, multiple patches: This offline case is currently crashing. We anticipate a relatively simple fix, but are not delaying the CABLE-2.0 release to include it.
Albedo: As reported in Kowalczyk et al. (submitted to AMOJ), the combination of the snow-free soil albedo field and the choice of reflectance and transmittance parameter values used in ACCESS CMIP5 runs led to low surface albedo, particularly in northern hemisphere in summer. The reflectance and transmittance values have now been recalculated and latest tests show improved surface albedo. The new values are provided in the default vegetation parameter file (CABLE-AUX/code/biogeochem/def_veg_params.2.0a.txt) while those values used for the CMIP5 submission are in def_veg_params.1.8a.txt. This issue would benefit from continued work; a parameterisation for snow-free soil albedo is being explored at UNSW.
Carbon / CASA-CNP: CABLE-2.0 is provided with the CASA-CNP biogeochemical pool code but this is not fully set up. CASA-CNP is coupled to CABLE-2.0 for offline simulations (Section 5.4) but reliable simulations require a process for spinning up the carbon pools (and nitrogen and phosphorus pools if nutrient limitation is switched on). Spin-up procedures for CASA-CNP will be provided with the next CABLE release. If you wish to test CABLE with CASA-CNP, please note that CASA-CNP has a daily timestep and the NEE output will not show a diurnal cycle (e.g. Tumba_CNP case vs Tumba_oldC case on http://www.pals.unsw.edu.au, workspace: CABLE2.0_benchmark). An exception currently exists when Carbon only (noNP) is simulated in the CASA-CNP module (i.e. switch ‘icycle’ is set to 1); the apparent diurnal cycle is using a constant value of soil respiration from the day before, added to the current plant carbon fluxes (e.g. Tumba_C case on PALS). As the diurnal cycle comparison is quite useful, the NEE reporting frequencies for various CASA-CNP setups will be reconsidered at a later date.
For ACCESS simulations, a test coupling of CASA-CNP to CABLE has been achieved but this needs to be merged with the offline CASA-CNP case. It was decided not to hold up the CABLE-2.0 release for this merge; providing CASA-CNP for ACCESS is a high priority for the next CABLE version.
CASA-CNP is our preferred option for simulating carbon respiration fluxes. The photosynthesis flux does not require CASA-CNP and is calculated as part of cable_canopy.F90. This should provide reasonable results, depending on the values chosen for vcmax (set in the vegetation parameter file). Respiration fluxes are still available using the original CABLE carbon routines in cable_carbon.F90. Plant respiration is calculated in the subroutine ‘plantcarb’, while there are two options for soil respiration in ‘soilcarb’. These fluxes depend on the carbon pool sizes and rates that are initialized through the vegetation parameter file. Note that in ACCESS simulations, these pool sizes will be reset every time the model is restarted (typically every 3 months) i.e. pool size should be considered effectively constant. There are currently no plans to fix this, since CASA-CNP will be replacing these original carbon routines.
ACCESS runs: ACCESS runs occasionally crash in parts of the code unrelated to CABLE. An instability occurs in the Himalayan region. Some test versions of CABLE appeared to make this problem worse, apparently linked to rapid melting of snow and exposure of the underlying soil albedo.
Parts of this document are taken from the CABLE v1.4b User Guide, written by Gab Abramowitz, Ying- Ping Wang and Bernard Pak.
Contributions to technical support for CABLE are provided by the NCI National Facility at the ANU, and by the Computational Modelling Systems team of the ARC Centre of Excellence for Climate System Science.
Abramowitz, G. (2012), Towards a public, standardized, diagnostic benchmarking system for land surface models, Geosci. Model Dev., 5, 819-827.
Bi et al., The ACCESS Coupled Model: Description, Control Climate and Evaluation, submitted to AMOJ.
Corbin, K. D. and R. M. Law, Extending atmospheric CO2 and tracer capabilities in ACCESS, CAWCR Technical Report, No 035, 81pp, http://www.cawcr.gov.au/publications/technicalreports/CTR_035.pdf, 2011.
Ganguly S., A. Samanta, M. A. Schull, N. V. Shabanov, C. Milesi, R. R. Nemani, Y. Knyazikhin, R. B. Myneni, Generating vegetation leaf area index Earth system data records from multiple sensors. Part 2: Implementation, Analysis and Validation. Remote Sens. Environ., 112, 4318–4332, doi:10.1016/j.rse.2008.07.013, 2008.
Gao F., J. T. Morisette, R. E. Wolfe, G. Ederer, J. Pedelty, E. Masuoka, R. Myneni, B. Tan and J. Nightingale, An Algorithm to Produce Temporally and Spatially Continuous MODIS-LAI Time Series. IEEE Geosci. Remote Sens. Letts., 5, 60-64, doi: 10.1109/LGRS.2007.907971, 2008.
Global Soil Data Task Group, Global Gridded Surfaces of Selected Soil Characteristics (IGBP-DIS). [Global Gridded Surfaces of Selected Soil Characteristics (International Geosphere-Biosphere Programme - Data and Information System]). Data set. Available on-line http://www.daac.ornl.gov from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/569, 2000.
Kowalczyk, E. A., Y. P. Wang, R. M. Law, H. L. Davies, J. L. McGregor, and G. S. Abramowitz, The CSIRO Atmosphere Biosphere Land Exchange (CABLE) model for use in climate models and as an offline model. (CSIRO Marine and Atmospheric Research Paper; 013) Aspendale, Vic.: CSIRO Marine and Atmospheric Research. 43 p. http://www.cmar.csiro.au/e-print/open/kowalczykea_2006a.pdf, 2006.
Kowalczyk, E. A., L. Stevens, R.M. Law, M. Dix, Y.P. Wang, I.N. Harman, K. Haynes, J. Srbinovsky, B. Pak and T. Ziehn, The land surface model component of ACCESS: description and impact on the simulated surface climatology, submitted to AMOJ.
Lawrence, P. J., Feddema, J.J., Bonan, G.B., Meehl, G.A., O’Neill, B.C., Oleson, K.W., Levis, S., Lawrence, D.M., Kluzek, E., Lindsay K. and Thornton, P.E., Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100, J. Climate, 25, 3071-3095, DOI: 10.1175/JCLI-D-11-00256.1, 2012.
Wang, Y. P., Law, R. M. and Pak, B., A global model of carbon, nitrogen and phosphorus cycles for the terrestrial biosphere, Biogeosciences, 7, 2261-2282, doi:10.5194/bg-7-2261-2010, 2010.
Wang, Y. P., E. Kowalczyk, R. Leuning, G. Abramowitz, M. R. Raupach, B. Pak, E. van Gorsel, and A. Luhar, Diagnosing errors in a land surface model (CABLE) in the time and frequency domains, J. Geophys. Res., 116, G01034, doi:10.1029/2010JG001385, 2011.
Zobler, L. A world soil file for global climate modelling, Technical Report 87802, NASA Goddard Institute for Space Studies, 1988.