基于最大熵增模型对京津冀地表通量的估算与评估

Estimation of land surface heat fluxes in the Beijing-Tianjin-Hebei region using a maximum entropy production model

  • 摘要: 利用观测数据和最大熵增(Maximum Entropy Production,MEP)模型,估算了京津冀地区小汤山、顺义和武清3个站的地表感热通量和潜热通量。模型的输入量为地表净辐射、地表温度以及地表比湿,其中地表温度和地表比湿分别通过地表向上、向下长波辐射和相对湿度估算得到。将MEP模型计算结果与涡动相关(Eddy Covariance,EC)观测得到的感热通量和潜热通量进行比较,验证评估MEP模型。此外,将MEP模型计算结果与另一种简化计算方法(M20模型)以及7种再分析资料(NCEP1、NCEP2、MERRA2、ERA-5、ERA-Interim、JRA55、CRA)的日平均地表感热和潜热通量进行比较,对比分析它们在京津冀地区计算地表感热和潜热通量的准确度。结果表明:MEP模型计算的地表潜热通量和感热通量与涡动相关观测结果较为接近,具有相似的日变化、月变化和季变化特征。相比M20方法和再分析资料,MEP模型的计算结果与观测吻合得更好,具有更小的均方根误差和平均偏差。因此,最大熵增模型在京津冀地区计算地表热通量的准确度和可信度较高,在该地区具有较好的适用性。

     

    Abstract: Surface sensible and latent heat fluxes at the Xiaotangshan, Shunyi and Wuqing sites in the Beijing-Tianjin-Hebei region are calculated using a Maximum Entropy Production model (MEP) and observation data. The input data of the MEP model are net radiation, temperature and humidity. Among them, surface temperature and specific humidity are estimated respectively by surface upward and downward long wave radiation and relative humidity. The results of the MEP model are compared with Eddy Covariance (EC) observations to evaluate the model performance. In addition, daily averaged sensible and latent heat fluxes calculated by the MEP model at the three sites are also compared with the results from a simplified method (M20) and seven reanalysis datasets (NCEP1, NCEP2, MERRA2, ERA-5, ERA-Interim, JRA55, CRA) to analyze the accuracy of these methods for acquiring the surface sensible and latent heat fluxes in the Beijing-Tianjin-Hebei region. The results show that the fluxes calculated by the MEP model are generally consistent with observations and show similar diurnal, monthly and seasonal characteristics with those observed. Compared with results of the M20 method and reanalysis datasets, the results of the MEP model agree better with observations with smaller RMSEs (Root Mean Square Error) and average deviations. Therefore, the MEP model has high accuracy and reliability in calculating surface heat fluxes in the Beijing-Tianjin-Hebei region, and shows a good applicability in this region.

     

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