The effectiveness and efficiency of two state‐of‐the‐art global sensitivity analysis (SA) methods, the Morris and surrogate‐based Sobol' methods, are evaluated using the Weather Research and Forecasting (WRF) model, version 3.6.1. The sensitivities of precipitation and other related meteorological variables to 11 selected parameters in the new Kain‐Fritsch Scheme, WRF Single‐Moment 6‐class Scheme, and Yonsei University Scheme are then investigated. The results demonstrate that (1) the Morris method is effective and efficient for screening important parameters qualitatively, and with recommended settings of levels p = 8 and replication times r = 10 only 10 × (D + 1) WRF runs are required, where D is the dimension of parameter space; (2) Gaussian process regression (GP) is the best method for constructing surrogates, and the GP‐based Sobol' method can provide reliable quantitative results for sensitivity analysis when the number of WRF runs exceeds 200; and (3) the sensitivity index μ∗ in the Morris method is closely related to the Sobol' index ST, and even for qualitative sensitivity analysis, the GP‐based Sobol' method is more efficient compared to the Morris method. The SA results show that larger values of the downdraft‐related parameter x1, entrainment‐related parameter x2, and downdraft starting height x3 significantly decrease rainfall, while the maximum allowed value for the cloud ice diameter x6 has a moderate decreasing effect on precipitation. This work is useful for further tuning of the WRF to improve the agreement between the climate model and observations.

Land surface albedo is a significant parameter for maintaining a balance in surface energy. It is also an important parameter of bare soil surface albedo for developing land surface process models that accurately reflect diurnal variation characteristics and the mechanism behind the solar spectral radiation albedo on bare soil surfaces and for understanding the relationships between climate factors and spectral radiation albedo. Using a data set of field observations, we conducted experiments to analyze the variation characteristics of land surface solar spectral radiation and the corresponding albedo over a typical Gobi bare soil underlying surface and to investigate the relationships between the land surface solar spectral radiation albedo, solar elevation angle, and soil moisture. Based on both solar elevation angle and soil moisture measurements simultaneously, we propose a new two‐factor parameterization scheme for spectral radiation albedo over bare soil underlying surfaces. The results of numerical simulation experiments show that the new parameterization scheme can more accurately depict the diurnal variation characteristics of bare soil surface albedo than the previous schemes. Solar elevation angle is one of the most important factors for parameterizing bare soil surface albedo and must be considered in the parameterization scheme, especially in arid and semiarid areas with low soil moisture content. This study reveals the characteristics and mechanism of the diurnal variation of bare soil surface solar spectral radiation albedo and is helpful in developing land surface process models, weather models, and climate models.

We determined the effects of nitrogen (N) loading (35 kg N ha -1 y -1 ) on the needle morphological and photosynthetic traits of 4-year-old seedlings of Japanese larch (Larix kaempferi) under different three light intensities (open, 50% and 20% light) to evaluate how they adjust to low light conditions. Nitrogen deposition in forests has been increasing in East Asia. Although Japanese larch is not native to Hokkaido, northern Japan, this light demanding tree species is now a promising forestation species and reaches to the age of bearing cones for regeneration. Forest gaps affects the success in regeneration. This light-demanding tree is a promising reforestation species, but its success at natural regeneration depends on the availability of light. The net photosynthetic rate at light saturation (P sat ) decreased with increasing shading. Nitrogen addition increased P sat in unshaded seedlings but not in 50% and 20% light seedlings. Independent of added N, photosynthetic adjustment to the light environment was regulated by the allocation of N between rubisco and light-harvesting proteins. P sat in full sun was higher with N than without; the difference would be related to changes of stomatal limitation (Ls). With added N, larch seedlings in shade may store extra N in rubisco. Therefore, though Japanese larch is light demanding conifer, at the N level used in this study, shaded Japanese larch seedlings can regenerate in forest floor.

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