Summary of the article on CLM3:

### Improvements in CLM3

The CLM3 model implemented several key improvements:

1. Software upgrades for better performance and model output
2. Rewriting the code to support vector-based computational platforms
3. Improvements to biogeophysical parameterizations to address deficiencies in the coupled model climate

Two parameterization improvements had a notable impact:

1. Variable aerodynamic resistance for heat/moisture transfer from ground to canopy air based on canopy density, which reduced unrealistically high surface temperatures in semi-arid regions.
2. Addition of stability corrections to the 2-m air temperature calculation, reducing biases in this temperature.

CLM3 also introduced a default mode of competition between plant functional types (PFTs) for a shared soil column.

The article provides references to studies that analyze the climate statistics, land hydrological cycle, and evapotranspiration partitioning of the CLM3 model.