Estimation of Surface Fluxes from Time-Series of Temperature and Soil Moisture

9804996 BRAS提出了一种从土壤变量和大气变量的时间序列估计地表热通量、感热通量和蒸发量的新方法。该方法消除了大多数现有算法获取地表通量所需的梯度估计的需要。它通过利用土壤和大气中热量和水分垂直运动的扩散类比来实现这一目标。在这种情况下，标量变量的垂直梯度可以表示为变量的半阶时间导数，而半阶时间导数又是所述变量在土壤和大气界面上的时间序列的加权积分。概念验证工作已经完成，但仍有许多悬而未决的问题，需要利用实地数据进行广泛核查。尚待解决的一些问题包括：1.适当地表示可能与土壤、植被或状态有关的参数；2.将这一概念扩展到估计区域上的通量，并适当地处理这种情况下特性的异质性；3.探索该方法假设的稳健性。他的工作承诺：1.提高我们利用遥感观测来量化地表水文气象通量的能力；2.提高量化区域能量平衡的能力；3.建议更好地对全球大气和陆地模式进行参数化。

9804996 Bras A novel method is proposed for estimating ground heat flux, sensible heat flux and evaporation at the surface from time series of soil variables and atmospheric variables. The method eliminates the need of estimating gradients required by most existing algorithms to obtain surface fluxes. It achieves this objective by exploiting diffusion analogies to the vertical movement of heat and moisture in the soil and atmosphere. In such cases the vertical gradient of a scalar variable can be expressed as the half order time derivative of the variable, which in turn is a weighted integral of the time series of the variable in question at the interface between the soil and the atmosphere. Proof-of-concept has been achieved but there are many outstanding issues and need for extensive verification with field data. Some of the questions yet to be addressed include: 1. properly representing parameters that may be soil, vegetation or state dependent; 2. expanding the concept to estimating fluxes over regions, and properly handling the heterogeneity of properties in that case; 3. explore the robustness of the assumptions of the method.T'his work promises to: 1. enhance our ability to utilize remotely sensedobservations to quantify surface hydrometeorological fluxes; 2. improve ability to quantify regional energy balances; 3. suggest better parameterizations of global atmospheric and land models.