How Does Global Warming Accelerate the Hydrological Cycle in the East Asian Monsoon Region? Atmospheric- and Terrestrial Moisture Pathways Analysis in a Regional Earth System Model

全球变暖如何加速东亚季风区的水文循环？

• 批准号: 391681070
• 负责人: Professor Dr. Harald Kunstmann
• 金额: --
• 依托单位: State Key Laboratory of Hydrology
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/391681070?language=en
• 关键词: How; Does; Global; Warming; Accelerate

Global warming is assumed to cause a global acceleration of the hydrological cycle. Accordingly, at the regional scale, this may modify weather regimes and likely increase the number of hydrometeorological extreme events. In the case of the East Asian monsoon region, such changes have already been observed and are expected to intensify, which is a potential threat for the regional economy. Moreover, water resources in the region are heavily affected by anthropogenic activity, which further modifies the regional hydrological cycle. However, the detailed mechanism linking the global warming and anthropogenic activities to changes in the East Asian monsoonal circulation, a regional acceleration of the hydrological cycle and an increase of extreme events is not fully understood yet.Traditional methods to investigate moisture residence times and thereby the speed of the hydrological cycle are generally limited by crude assumptions in the coupling between the land surface/subsurface and the atmosphere. On the one hand, climate models usually neglect lateral terrestrial water flows. On the other hand, sophisticated land surface models do not account for land-atmosphere feedbacks, as the state of the atmosphere is a fixed forcing input. In the last years, evaporation-tagging methods have been elaborated within regional climate models in order to investigate the fate of surface evaporated water in the atmosphere until it precipitates. In particular, an age-weighted evaporation-tagging algorithm has recently been introduced and applied for diagnosing the speed of the atmospheric branch of the hydrological cycle. This approach will now be extended to the full regional hydrological cycle:We will first enhance a fully coupled regional atmosphere-hydrology model system (WRF-HMS, i.e. a regional Earth System Model) with the effect of anthropogenic activities on water resources. Secondly, we will develop a new method to evaluate jointly the atmospheric and soil moisture pathways in this enhanced regional Earth System Model, based on an age-weighted evaporation- and precipitation-tagging algorithm. This allows the derivation of residence times and thereby conclusions on the speed and potential acceleration of the hydrological cycle. Thirdly, we will characterize the atmospheric situations when the additional description of lateral terrestrial water flows in the Earth System Model, as well as the description of water resource management, alters the atmospheric and soil moisture pathways and residence times in the case of the East Asian monsoon region. Finally, applying the newly developed methods to long term regional climate simulations and defined RCPs, we will provide a new perspective on the mechanism governing the acceleration of the hydrological cycle in the East Asian monsoon region. This also allows us to estimate the effect of water management.

全球变暖被认为是导致全球水文循环加速的原因。因此，在区域范围内，这可能会改变天气状况，并可能增加水文气象极端事件的数量。在东亚季风区，已经观察到这种变化，预计这种变化将加剧，这对区域经济构成潜在威胁。此外，该区域的水资源受到人类活动的严重影响，这进一步改变了区域水文循环。然而，全球变暖和人类活动与东亚季风环流变化之间的详细机制，水文循环的区域加速和极端事件的增加还没有得到充分的理解。传统的方法来调查水分停留时间，从而水文循环的速度通常受到陆地表面/地下和大气层。一方面，气候模式通常忽略陆地水的横向流动。另一方面，复杂的陆面模式不考虑陆-气反馈，因为大气状态是一个固定的强迫输入。过去几年，区域气候模型中详细阐述了蒸发标记方法，以调查大气中表面蒸发水在沉淀之前的命运。特别是，最近引入了一种年龄加权蒸发标记算法，并应用于诊断水文循环大气分支的速度。这种方法现在将扩展到整个区域水文循环：我们将首先加强一个完全耦合的区域大气水文模型系统（WRF-HMS，即区域地球系统模型），考虑人类活动对水资源的影响。其次，我们将开发一种新的方法来联合评估在这个增强的区域地球系统模型的大气和土壤水分路径，基于年龄加权蒸发和降水标记算法。这使得可以推导出停留时间，从而得出水文循环的速度和潜在加速的结论。第三，我们将描述大气情况时，地球系统模式中的横向陆地水流的额外描述，以及水资源管理的描述，改变大气和土壤水分的路径和停留时间的情况下，东亚季风区。最后，将新开发的方法应用于长期区域气候模拟和定义的区域气候参数，我们将为东亚季风区水文循环加速的机制提供新的视角。这也使我们能够估计水管理的效果。