Representing a new MODIS consistent land surface in the Community Land Model (CLM 3.0)

[1] Recently a number of studies have found significant differences between Moderate Resolution Imaging Spectroradiometer (MODIS) land surface mapping and the land surface parameters of the Community Land Model (CLM) of the Community Climate System Model (CCSM). To address these differences in land surface description, we have developed new CLM 3.0 land surface parameters that reproduce the physical properties described in the MODIS land surface data while maintaining the multiple Plant Functional Type (PFT) canopy and herbaceous layer representation used in CLM. These new parameters prescribe crop distributions directly from historical crop mapping allowing cropping to be described in CLM for any year from 1700 to current day. The new model parameters are calculated at 0.05 degrees resolution so they can be aggregated and used over a wider range of model grid resolutions globally. Compared to the current CLM 3.0 parameters, the new parameters have an increase in bare soil fraction of 10% which is realized through reduced tree, shrub, and crop cover. The new parameters also have area average increases of 10% for leaf area index (LAI) and stem area index (SAI) values, with the largest increases in tropical forests. The new land surface parameters have strong repeatable impacts on the climate simulated in CCSM 3.0 with large improvements in surface albedo compared to MODIS values. In many cases the improvements in surface albedo directly resulted in improved simulation of precipitation and near-surface air temperature; however, for the most part the existing biases of CCSM 3.0 remained with the new parameters. Further analysis of changes in surface hydrology revealed that the increased LAI of the new parameters resulted in lower overall evapotranspiration with reduced precipitation in CCSM 3.0. This was an unexpected result given that other research into the impacts of vegetation change suggests that the new parameters should have the opposite impact. This suggests that while the new parameters significantly improve the climate simulated in CLM 3.0 and CCSM 3.0, the new surface parameters have limited success in rectifying surface hydrology biases that result from the parameterizations within the CLM 3.0.

[1]  Feng Gao,et al.  Using MODIS BRDF and albedo data to evaluate global model land surface albedo , 2004 .

[2]  N. Ramankutty,et al.  Estimating historical changes in global land cover: Croplands from 1700 to 1992 , 1999 .

[3]  Ramakrishna R. Nemani,et al.  Implementation of a hierarchical global vegetation classification in ecosystem function models , 1996 .

[4]  R. Dickinson,et al.  Comparison of seasonal and spatial variations of leaf area index and fraction of absorbed photosynthetically active radiation from Moderate Resolution Imaging Spectroradiometer (MODIS) and Common Land Model , 2004 .

[5]  K. Oleson,et al.  Assessment of global climate model land surface albedo using MODIS data , 2003 .

[6]  Pedro Viterbo,et al.  The land surface‐atmosphere interaction: A review based on observational and global modeling perspectives , 1996 .

[7]  P. Sellers.  Canopy reflectance, photosynthesis and transpiration , 1985 .

[8]  S. Running,et al.  Global products of vegetation leaf area and fraction absorbed PAR from year one of MODIS data , 2002 .

[9]  I. C. Prentice,et al.  Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model , 2003 .

[10]  N. Batjes.  A world dataset of derived soil properties by FAO–UNESCO soil unit for global modelling , 1997 .

[11]  Mei Zhao,et al.  The impact of land cover change on the atmospheric circulation , 2001 .

[12]  G. Meehl,et al.  The Importance of Land-Cover Change in Simulating Future Climates , 2005, Science.

[13]  R. Dickinson,et al.  Coupling of the Common Land Model to the NCAR Community Climate Model , 2002 .

[14]  Keith W. Oleson,et al.  Landscapes as patches of plant functional types: An integrating concept for climate and ecosystem models , 2002 .

[15]  Alan H. Strahler,et al.  Global land cover mapping from MODIS: algorithms and early results , 2002 .

[16]  Peter E. Thornton,et al.  Technical Description of the Community Land Model (CLM) , 2004 .

[17]  J. Townshend,et al.  A new global 1‐km dataset of percentage tree cover derived from remote sensing , 2000 .

[18]  R. DeFries,et al.  Global distribution of C3 and C4 vegetation: Carbon cycle implications , 2003 .

[19]  R. Dickinson,et al.  Impact of new land boundary conditions from Moderate Resolution Imaging Spectroradiometer (MODIS) data on the climatology of land surface variables , 2004 .

[20]  C. Field,et al.  Bidirectional Interactions between the Biosphere and the Atmosphere—introduction , 1998 .

[21]  J. Polcher,et al.  A statistical study of the regional impact of deforestation on climate in the LMD GCM , 1994 .

[22]  R. DeFries,et al.  Effects of Land Cover Conversion on Surface Climate , 2002 .

[23]  J. Townshend,et al.  Global Percent Tree Cover at a Spatial Resolution of 500 Meters: First Results of the MODIS Vegetation Continuous Fields Algorithm , 2003 .

[24]  Roger A. Pielke,et al.  Interactions between the atmosphere and terrestrial ecosystems: influence on weather and climate , 1998 .

[25]  H. Storch,et al.  Statistical Analysis in Climate Research , 2000 .

[26]  A. Pitman,et al.  Relative climatic effects of landcover change and elevated carbon dioxide combined with aerosols: A comparison of model results and observations , 2001 .

[27]  R. Dickinson,et al.  The Community Land Model and Its Climate Statistics as a Component of the Community Climate System Model , 2006 .

[28]  Feng Gao,et al.  Land boundary conditions from MODIS data and consequences for the albedo of a climate model , 2004 .

[29]  H. Mooney,et al.  Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere , 1997, Science.

[30]  N. C. Strugnell,et al.  First operational BRDF, albedo nadir reflectance products from MODIS , 2002 .

[31]  D. Roy,et al.  An overview of MODIS Land data processing and product status , 2002 .

[32]  Ann Henderson-Sellers,et al.  Impacts of Tropical Deforestation. Part I: Process Analysis of Local Climatic Change , 1996 .