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首页> 外文期刊>Journal of Geophysical Research, D. Atmospheres: JGR >Incorporating water table dynamics in climate modeling: 3. Simulated groundwater influence on coupled land-atmosphere variability
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Incorporating water table dynamics in climate modeling: 3. Simulated groundwater influence on coupled land-atmosphere variability

机译：将地下水位动态纳入气候模拟：3.模拟地下水对陆地-大气耦合变化的影响

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Using a coupled regional climate-hydrologic modeling system, RAMS-Hydro, we investigate the role of the water table dynamics in controlling soil moisture, evapotranspiration (ET), boundary layer dynamics, and precipitation. In an earlier study we showed that a shallow water table can primarily exist in two types of hydrologic settings in North America: the humid river valleys and coastal regions in the east and the arid or semiarid intermountain valleys in the west. We also showed that the shallow water table in these settings can lead to significantly wetter soils than would exist without the presence of the water table. Here, we show that the water table–induced wetter soil directly maps into enhanced ET in the western setting, where soil water is a strong limiting factor of ET flux, but it is less likely to be the case in the more humid eastern setting where soil water is not limiting in general. We also ask whether any resulting enhanced ET will directly map into enhanced precipitation. Our hypothesis is that this can occur through two primary mechanisms: local, ET-driven enhancement of convective precipitation and enhanced regional or lateral moisture convergence caused by altered soil moisture fields, and hence altered ET, far from the region of concern. We find that, indeed, water table–induced higher ET in the arid west results in greater convective precipitation and that ET-precipitation coupling is primarily through local feedback pathways and precipitation recycling, with the main role of large-scale moisture convergence as an initiator of convection following dry periods. Transitioning to the more humid regions farther east, the greater atmospheric (relative to surface) control of precipitation progressively obscures any potential effects of the water table, and the effects of large-scale moisture convergence tend to dominate.
机译：我们使用一个耦合的区域气候水文模型系统RAMS-Hydro，研究了地下水位动态在控制土壤湿度，蒸散量（ET），边界层动态和降水中的作用。在较早的研究中，我们表明，浅水位主要存在于北美的两种水文环境中：东部的湿润河谷和沿海地区以及西部的干旱或半干旱山间山谷。我们还表明，与没有地下水位的情况相比，在这些环境中的浅水位会导致土壤明显湿润。在这里，我们表明，在西部环境中，地下水位引起的湿润土壤直接映射到增强的ET中，那里的土壤水是ET通量的强大限制因素，但在较潮湿的东部环境中，这种情况不太可能发生土壤水一般没有限制。我们还询问是否产生的任何增强的ET都将直接映射为降水增加。我们的假设是，这可能通过两种主要机制发生：局部，ET驱动的对流降水增强，以及土壤湿度场变化从而引起ET改变的区域或侧向水分会聚增强，而远离关注区域。我们发现，确实，干旱地区西部由地下水位引起的较高的ET导致更大的对流降水，而ET与降水的耦合主要是通过局部反馈途径和降水循环利用，其主要作用是大规模的水分汇聚。干燥期后的对流。过渡到更东部的较湿润地区，更大的大气（相对于地表）降水控制将逐渐掩盖地下水位的任何潜在影响，而大规模水汽收敛的影响往往占主导地位。

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