Constraining Plant Hydraulics With Microwave Radiometry in a Land Surface Model: Impacts of Temporal Resolution
Constraining Plant Hydraulics With Microwave Radiometry in a Land Surface Model: Impacts of Temporal Resolution
复制标题
用微波辐射法在陆地表面模型中约束植物水力学：时间分辨率的影响
DOI：
10.1029/2023wr035481
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发表时间：
2023-11
影响因子：
5.4
通讯作者：
N. Holtzman;Yujie Wang;Jeffrey D. Wood;Christian Frankenberg;A. Konings
中科院分区：
文献类型：
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作者：
N. Holtzman;Yujie Wang;Jeffrey D. Wood;Christian Frankenberg;A. Konings
植被含水量（VWC）在蒸腾作用、植物死亡率和野火风险中起着关键作用。虽然陆面模型现在经常包含工厂水力学计划，有几个直接VWC测量，以约束这些模型在全球范围内。针对这一数据差距提出的一个解决办法是被动微波遥感，它对VWC的时间变化很敏感。在这里，我们测试的方法，使用合成微波观测约束VWC和地表土壤水分在气候建模联盟的土地模型。我们进一步研究了VWC亚日常观测的可能效用，这可以通过地球静止轨道上的卫星或多颗卫星的组合来获得。这些高时间分辨率的观测可以改善生态系统参数，碳和水通量以及地下水力学的确定，相对于目前可用的每日两次太阳同步观测模式。我们发现，在日周期中的四个不同时间（例如可以从两个太阳同步卫星获得）合并观测比每天两次观测对水和碳通量提供了更好的约束。例如，在干旱期间，当使用每天四次相对于每天两次的观测时，预计蒸散量和总初级生产力的均方根误差减少了约40%。增加每小时观测的整个昼夜周期没有进一步改善推断的参数和通量。我们的观测策略的比较可能是有益的，在未来的卫星任务的设计，研究植物水力学，以及当使用现有的遥感数据来研究植被水分胁迫响应。
Vegetation water content (VWC) plays a key role in transpiration, plant mortality, and wildfire risk. Although land surface models now often contain plant hydraulics schemes, there are few direct VWC measurements to constrain these models at global scale. One proposed solution to this data gap is passive microwave remote sensing, which is sensitive to temporal changes in VWC. Here, we test that approach by using synthetic microwave observations to constrain VWC and surface soil moisture within the Climate Modeling Alliance Land model. We further investigate the possible utility of sub‐daily observations of VWC, which could be obtained through a satellite in geostationary orbit or combinations of multiple satellites. These high‐temporal‐resolution observations could allow for improved determination of ecosystem parameters, carbon and water fluxes, and subsurface hydraulics, relative to the currently available twice‐daily sun‐synchronous observational patterns. We find that incorporating observations at four different times in the diurnal cycle (such as could be available from two sun‐synchronous satellites) provides a significantly better constraint on water and carbon fluxes than twice‐daily observations do. For example, the root mean square error of projected evapotranspiration and gross primary productivity during drought periods was reduced by approximately 40%, when using four‐times‐daily relative to twice‐daily observations. Adding hourly observations of the entire diurnal cycle did not further improve the inferred parameters and fluxes. Our comparison of observational strategies may be informative in the design of future satellite missions to study plant hydraulics, as well as when using existing remotely sensed data to study vegetation water stress response.