SHAW模式的改进及其在黄土高原半干旱区的模拟研究

Improvement of the Land Surface Model SHAW and Simulation Analysis in the Loess Plateau

陆面过程模拟研究中的一个关键问题是如何准确的计算陆气间能量交换,但现有的陆面过程模式模拟的湍流通量与观测值间仍然存在较大偏差,因此改进湍流通量的参数化方案对于提高陆面过程模式模拟能力有重要意义。本研究通过改进陆面过程模式SHAW中的热力粗糙度方案,以及引入干表层蒸发方案,以期改善湍流通量的模拟能力。在此基础上利用黄土高原半干旱区SACOL站观测资料,进行模式改进前后的单点模拟对比试验,研究其参数化方案改进对陆面过程模拟的影响。结果表明:改进后的SHAW模式能够合理地模拟黄土高原半干旱区陆面特征的变化趋势,模拟值与观测值偏差较小。与原来的SHAW模式模拟结果相比,改进后的SHAW_MOD模式显著提高了湍流通量的模拟能力,并改善了净辐射和深层土壤温度的模拟,但对土壤湿度的改进并不明显,这可能与土壤内部水热传输过程及相关参数化方案有关,还有待做进一步研究。

A key problem in the land surface simulation study is accurately modeling the surface energy budget.But the turbulent heat flux simulated by current land surface models was remarkable deviated from the observations.Therefore,parameterizing the surface tur-bulent heat transport process is vital for improving land surface simulation ability.In this study,land surface model SHAW is em-ployed,by improving the thermal roughness parameterization schemes and introducing dry surface layer evaporation schemes to improve the turbulent heat flux simulation.By using the data obtained at SACOL site in Loess Plateau and the modified SHAW model,a single point simulation is studied.Simultaneously,the SHAW model simulations are compared to investigate the effect of the modified param-eterization schemes.Results suggest that the modified model can well simulate all the change tendency of the land surface characteris-tics in semi-arid region,the bias was small between simulations and observations.Compared with the original SHAW model,the modified model significantly improved the turbulent heat flux simulation,and better simulated net radiation,but the simulated soil tem-perature and moisture were not obviously improved,this maybe attribute to the water and heat transfer process and parameterization schemes related in the soil layers and need to study in the future.