[an error occurred while processing this directive] [an error occurred while processing this directive] CCSM Summer 2000 Workshop, LWG Meeting report

Report of the CCSM Land Model Working Group

 

Fifth Annual Community Climate System Model Workshop

Co-Chairs: Gordon Bonan and Robert Dickinson

The Village at Breckenridge,   28 June 2000

 

 

The Land Model Working Group (LMWG) has agreed to work toward implementing a unified treatment of land that includes land biophysics, including hydrology and river routing, interactive vegetation (dynamic leaf area indices and changing vegetation types), soil biogeochemistry as driven by vegetation, and any climatically significant source term that is delivered to the atmosphere (e.g., mineral aerosol, plant organic emissions, etc.). Where appropriate this work will be done in close collaboration with and intended to meet the requirements of the Biogeochemistry Working Group.

 

The most immediate objectives over the next several months are: a) to complete the evaluation of the Common Land Model (CLM0) as an improved biophysics package to be proposed for implementation in CCSM 2.0, and b) to reformulate our efforts to reduce or eliminate the most immediate obstacles toward achieving the desired unified treatment. Essentially all the discussion and presentations were directed toward one or another of these objectives or the best way to resolve conflicts between the two objectives.

 

Xubin Zeng, UA, reported on results from a control simulation with CLM (latest beta) coupled to CCM3 and driven by 17 years of AMIP2 data. Comparisons with LSM and observations indicated a major improvement in the seasonality of runoff and substantial reduction of the current cold bias. No climatic fields were made noticeably worse compared to LSM by use of CLM. However, global annual runoff still had a significant low bias, albedos appeared to be too high, and some cold temperature bias remained. Z.-L. Yang has provided an improved treatment of runoff to remove the low bias, and Zeng has developed improved albedos based on a UA MS thesis of Xue Wei, which will be incorporated into the proposed final version of CCM0 and evaluated with a repeat 17 year simulation. This version will also be provided to NCAR, where the code needed to link it into the CSM modeling system will be developed, and to Paul Hauser at DAO who has assumed responsibility for any scientific oversight needed to complete the task.

 

Keith Oleson and Gordon Bonan, NCAR, have compared the formulation of CLM with that of LSM and assessed differences in performance from use of BOREAS data. In doing so they have discovered 2 obstacles to use of CLM for support of modeling interactive vegetation and soil biogeochemistry: a) the current stomatal formulation requires a significant amount of further effort to be able to use it to calculate leaf carbon fluxes, and it is not clear whether changes that might be made would impact the evapotranspiration, hence climate simulation; and b) the current choice of the IGBP biome land cover representation as obtained from AVHRR and MODIS 1-km data is inappropriate for representing needed parameters.

 

Z.-L. Yang, UA, reported a wide variety of observational validations of snow model performance. The CLM snow model and another model he has developed showed much better agreement with the observations than did LSM.

 

Ian Baker, CSU, has carried out a variety of comparisons of CLM with SiB in the context of tower data. He reported that CLM gave much more realistic winter soil temperatures but that he found a as yet unexplained 2 degree warm bias at the solid surface during summer.

 

Paul Houser, DAO, presented applications of CLM in the context of his land data assimilation system. The CLM model has been designed taking into account requirements of land data assimilation and so has several important features that are not contained in many of the simpler land models, such as the good vertical resolution for its top soil layers.

 

S. Levis reported the current status of incorporation of river routing into the CLM. Some of the discussion suggested a possible need for more community support for this activity.

 

Important decisions taken at the workshop were:

 

a)      to move ahead with CLM to develop adequate arguments that it is ready for implementation as part of CCSM-2. This evidence needs to be presented to the SSC by the time of their next meeting, currently targeted for September. How much evidence is needed is not exactly established, but CLM as an improved land biophysics model would be on solid ground, if the SSC could be provided the draft BAMS article summarizing the overall concept of CSM, now being prepared by Dai et al., and the documentation of the CLM0 coupled simulation, as prepared by Zeng et al. Adequacy of code documentation could be established by having at least 3 members of the LMWG who could state they had compared the documentation of the code with the code and could not find any divergences or any significant code features that had not been reported in the documentation.

 

 

b)      to develop a plant functional type land cover representation as an alternative to that now used in CLM to be made available as part of the CLM public release; the initial suggestion from Bonan is use of the LSM PFTs expanded to account for climatic differences and to distinguish between crops. Some public discussion is needed before the PFTs to be used can be finalized. How many crops should we include? What do we do with lichen and moss, which are not currently considered by LSM, etc.?

 

 

c)      to work toward increasing the contributions of the land ecological and biogeochemical communities into the formulation of its future models.

  

 Participants

 

FirstName

LastName

email

Joyce

Almaguer-Reisdorf

joycee@alumni.rice.edu

Ian

Baker

baker@atmos.colostate.edu

Anjuli

Bamzai

abamzai@nsf.gov

Jason

Bell

jbell@es.ucsc.edu

Michael

Bosilovich

mikeb@dao.gsfc.nasa.gov

Robert

Boucher

rboucher@wsicorp.com

Yong-Jiu

Dai

dai@eas.gatech.edu

Roger

Dargaville

ffrjd@uaf.edu

Robert

Dickinson

robted@eas.gatech.edu

Johannes

Feddema

feddema@ukans.edu

Arthur

Few

few@rice.edu

Inez

Fung

ifung@uclink4.berkeley.edu

Lydia

Gates

LGates@lbl.gov

Andrea

Hahmann

hahmann@atmo.arizona.edu

Danny

Harvey

harvey@ucar.edu

Forrest

Hoffman

forrest@esd.ornl.gov

Paul

Houser

Paul.Houser@gsfc.nasa.gov

Zavareh

Kothavala

zav@ucar.edu

Chung-Chieng

Lai

cal@LANL.GOV

Samuel

Levis

slevis@ucar.edu

Susan

Marshall

susanm@uncc.edu

Robert

Oglesby

roglesby@purdue.edu

Keith

Oleson

oleson@ucar.edu

Elisabetta

Pierazzo

betty@lpl.arizona.edu

Peter

Rayner

peter.rayner@dar.csiro.au

Steve

Running

swr@ntsg.umt.edu

Adam

Schlosser

adam@cola.iges.org

Frank

Selten

selten@ucar.edu

Muhammad

Shaikh

shaikh@eas.gatech.edu

Jeffrey

Shorter

jshorter@wsicorp.com

Lisa

Sloan

lcsloan@emerald.ucsc.edu

Mark

Snyder

msnyder@es.ucsc.edu

John

Taylor

jtaylor@mcs.anl.gov

Starley

Thompson

thompson59@llnl.gov

Zong-Liang

Yang

liang@hwr.arizona.edu