北京郊区草地夏季能量收支平衡的数值模拟

Numerical simulation of surface energy budget balance over grassland in Beijing suburban area in summer

北京郊区地表能量分配可能影响北京地区的天气和气候。为了进一步检验陆面过程模式对北京郊区具有代表性的稀疏草地地表能量分配的模拟能力,利用原版和改进版简化生物圈模式(Si B2,Simple Biosphere Model 2)模拟了2010年7月22日—8月5日期间北京郊区阳坊镇坦克打靶场草地的辐射平衡、能量收支以及地表热通量。并将模拟结果与实际测量的数据进行对比,结果表明:1)原版Si B2低估净辐射11.32%,改进版Si B2则低估净辐射5.81%,主要原因是改进版Si B2更新了土壤热传导率计算方法,从而提高了土壤温度(包括地表温度)模拟结果的精度,进而改善了地表向上的长波辐射模拟结果的准确性;2)改进版Si B2同时改善了感热通量和潜热通量的模拟结果,但是原版Si B2和改进版Si B2均低估了土壤热通量。

Weather and climate in Beijing area may be affected by surface energy partitioning in Beijing suburbs. To evaluate the performance of land surface models in energy partitioning simulation over sparse grasslands in Beijing suburbs,the original and modified versions of Simple Biosphere Model 2（ Si B2） are applied to simulate the surface radiation balance,turbulent energy budget,and soil temperature and moisture over a tank exercise field in Beijing suburban area from 22 July to 5 August 2010. Simulated results are compared against the direct measurements. Results show that： 1） The modified Si B2 underestimates net radiation by 5. 81% when the original Si B2 underestimates net radiation by 11. 32%. The modified Si B2 where the soil thermal conductivity is updated can better simulate the soil temperature（ including the soil surface temperature） and the upward-wave radiation; 2） The modified Si B2 can better simulate the sensible heat and latent heat fluxes,but both the original and modified Si B2 underestimate the soil heat flux.