气象学报2012，Vol.70Issue(5)：1137-1148,12.
黄土高原自然植被下垫面陆面过程参数研究
A study of the parameterization of land-surface processes over the natural vegetation surface of Loess Plateau
摘要
Abstract
Based on the data observed at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) , the physical parameters related to land-surface processes over the natural vegetation surface of Loess Plateau are calculated. The paper studied averaged diurnal variations and the frequency distributions of the bulk transfer coefficients in the different seasons, and analyzed the trend of the surface roughness as well as effects of precipitation on the roughness. Monthly averages of the roughness in a normal year of precipitation have more changes compared with those in a dryer year since precipitation increasing tends to increase the roughness. The roughness in a normal year is 9 ×10-3m, while the roughness in a dryer year decreases to 6×l0-3m. The rainfall raises the roughness by increasing the vegetation cover and height. Relationships a-mong the bulk transfer coefficients and the two factors including surface roughness and the Richardson number are discussed. The role of dynamical transfer in land-atmosphere energy exchange over the Loess Plateau is dominant. Additionally, the neutral bulk transfer coefficient for momentum is close to that over the movable dune at Naiman in Inner Mongolia and the neutral bulk transfer coefficient for sensible heat is close to that over Gobi. We also analyzed effects of solar elevation angle and soil moisture on surface albedo and preliminarily a multiple factorial parameterization formula of surface albedo is suggested. Generally, the albedo over the Loess Plateau is smaller than that over the desert of Dunhuang and larger than that over pine forests in Changbai Mountain. The various vegetation covers and soil types in the three regions lead to differences of albedo. By testing the simulation results of the albedo formula, it is found that the albedo with low solar elevation angles is sensitive to the other factors except soil moisture and solar elevation angle, while soil moisture and solar elevation angle affect the albedo with high solar elevation angles significantly. What's more, the soil thermal parameters including soil thermal conductivity and thermal diffusion are calculated as well. In the same soil moisture, the soil thermal conductivity is larger than that in desert of Dunhuang. In the end, a parameterization formula of soil thermal conductivity is gotten by fitting the thermal conductivity and the soil moisture.关键词
黄土高原/粗糙度/总体输送系数/反照率/土壤热传导率/土壤热扩散率Key words
Loess Plateau/Surface roughness/Bulk transfer coefficient/Surface albedo/Soil thermal conductivity/Soil thermal diffusion分类
天文与地球科学引用本文复制引用
李宏宇,张强,史晋森,赵建华,王胜..黄土高原自然植被下垫面陆面过程参数研究[J].气象学报,2012,70(5):1137-1148,12.基金项目
国家自然科学基金重点项目(40830957). （40830957）
