## 3 Results and Discussion
### Effects on Atmospheric Variables  
Air temperature and precipitation are two basic physical quantities for characterizing climate state, and are also two important indicators for evaluating the performance of atmospheric or climate models [39]. Figure 6 shows the distribution of 24-year mean 2-m air temperature (TA). It is apparent that both runs could reasonably reproduce the global distribution of TA (Figure 6a,b), which is characterized by TA being highest in low-latitude regions, gradually decreasing from the Equator to the Poles, being low in the Qinghai-Tibet Plateau and other large land areas, and consistent with NCEP data (Figure 6c). When considering the root dynamic distribution, the NEW run showed a greater or lesser decrease in TA in most parts of the world, especially for low-latitude regions (with 95% confidence level) such as South Asia, the Amazon, and South Africa. TA decreased up to 2 \({}^{\circ}\)C in these regions, mainly due to the apparent increase in evapotranspiration (see Section 3.1), which increased the latent heat flux. As a result, overall, the land released more heat to the atmosphere, resulting in cooling of the land surface and lower SH (see Section 3.1). Because the lower atmosphere is heated mainly by long-wave radiation emitted from the land surface, ultimately, the decrease in surface temperature in low latitudes reduced the TA in the corresponding area, resulting in a cooling effect. Figure 5: Annual gross primary production (GPP, g C m\({}^{-2}\) year\({}^{-1}\)) over 1982–2005 for: (**a**) the CTL run; (**b**) the NEW run; (**c**) MTE; (**d**) the difference between NEW and CTL. (Grid shaded regions are significant at the 95% confidence level according to Student’s \(t\)-test, and red frames outline grouped regions with significant differences, denoted as R1, R2, R3, R4, and R5.). Figure 7 shows the spatial distribution of global 24-year mean precipitation. Both runs showed a similar pattern for global precipitation, consistent with GPCC data (Figure 7a-c), with the heaviest precipitation distributed mainly in tropical regions, the Americas, and the east coast of Asia, which is affected by the summer monsoon and typhoons. However, North Africa, arid deserts, and the polar regions had relatively less precipitation. The differences in total precipitation between the two experiments were mainly concentrated in tropical regions. In the northeastern part of the Amazon and the west coast of Africa, total precipitation increased by 200 mm year\({}^{-1}\), and in South America, central Africa, and Indonesia, total precipitation increased by 50 to 100 mm year\({}^{-1}\) (Figure 7c). Compared with the GPCC, the new scheme partly overcame the underestimation of total precipitation over the northeastern Amazon, Indonesia, and the overestimation over south Asia. Figure 7d,e show the difference in large-scale and convective precipitation between NEW and CTL respectively. It is obvious that both large-scale and convective precipitation have consistent changes with regard to the total precipitation. In the northeastern Amazon, convective precipitation contributes more to the increase in total precipitation, which implies that in this area local climate changes result in the more frequent occurrence of convective weather, and in the west coast of central Africa large precipitation events contribute more to total precipitation. Generally, precipitation in a region is affected not only by local land-surface feedback, but also by large-scale moisture advection. However, the advection process itself may still be affected by the land-atmosphere interaction. Incorporation of the dynamic rooting scheme changes root water absorption, and therefore the temporal and spatial variation of soil moisture, ultimately affecting the calculation of terrestrial water fluxes. Advection processes then redistribute the water and energy toward the surface, and finally influence the upper atmospheric circulation. For precipitation, rising motion and vapor are two key factors.