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CLM4.5模式模拟安徽省淮南山地森林陆气交换过程

Simulating Land and Atmosphere Exchange Processes over a Mountainous Forest in Huainan of Anhui Province Using CLM4.5 Model

  • 摘要: 基于2010~2019年ERA5单层再分析资料,结合安徽省淮南森林观测站2016年5月1日至2017年4月30日的大气边界层塔(PBL塔)观测资料,驱动陆面模式CLM4.5(Community Land Model Version 4.5),模拟了淮南山地森林下垫面上的陆面过程,并比较分析了不同驱动场对其影响,同时设计了土壤质地对土壤湿度影响的三个模拟试验。结果表明,CLM4.5对淮南森林陆气交换过程表现了较好的模拟性能,PBL塔观测资料驱动的总体模拟效果优于ERA5再分析资料的。在辐射模拟方面,CLM4.5利用ERA5资料和PBL塔观测资料,都很好地模拟了辐射分量,特别是PBL塔观测资料驱动的全年模拟结果与观测相关系数达0.97以上,均方根误差在25.056 W m−2以下。ERA5再分析资料强迫模拟的相关系数略低,但也达到了0.92,均方根误差在29.939 W m−2以下。在土壤温度模拟方面,相关系数都达到0.98以上;土壤湿度模拟的相关系数都在0.86以上,但系统性偏高;对感热通量的模拟全年平均的相关系数分别为0.72和0.78。实测的三层土壤质地加上深层给定的土壤质地的数据对土壤湿度的模拟结果与观测最为接近,土壤质地的准确描述可以大幅提高土壤湿度的模拟。本研究发现ERA5单层再分析资料在淮南森林站精度较好,可以应用于该山地森林区域陆—气交换过程的模拟研究。

     

    Abstract: Using ERA5 single-level reanalysis data during 2010–2019 and meteorological observations from a PBL (planetary boundary layer) tower in a mountainous forest in Huainan from 1 May 2016 to 30 April 2017 as forcing data, the authors evaluated the performance of the CLM4.5 (Community Land Model Version 4.5) against observed canopy fluxes and micrometeorological data at this site. The effects of these two forcing datasets on model simulation were compared. Additionally, three simulation experiments were conducted to assess the influence of soil texture on soil moisture and improve model performance. The results showed that CLM4.5 performs well in simulating the land–atmosphere exchange processes in the Huainan mountainous forest, with simulations driven by PBL tower data outperforming those driven by ERA5 reanalysis data. Both datasets performed well in radiation simulation, with the PBL-driven simulation showing particularly strong performance, where the correlation coefficient exceeded 0.97 and RMSE (root mean square error) was below 25.056 W m−2. The ERA5 reanalysis data forced simulation showed a slightly lower correlation coefficient also reaching 0.92, with a RMSE below 29.94 W m−2. In soil temperature simulation, correlation coefficients were all above 0.98. The correlation coefficients of soil moisture simulation were above 0.86, but the values were systematically higher. The annual average correlation coefficients for sensible heat flux simulations were 0.72 and 0.78, respectively. The simulated results of the soil moisture with the measured three layers of soil texture combined with the deep given soil texture data were closest to the observations. Thus, accurate description of soil texture could greatly improve simulation results of soil moisture. This study demonstrates that ERA5 single-layer reanalysis data is reliable for simulating land–atmosphere exchange processes in Huainan’s forest and can be applied to similar regions in the north–south climate transition zone.

     

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