Modeling Anthropogenic Desiccation of the Aral Sea: A Unique Test of the Predictive Capabilities of a Regional Earth System Model

题目：模拟咸海人为干旱化：对区域地球系统模式预测能力的独特检验全球和区域地球系统模式（ESMs）在调查过去气候变化原因和预测未来人类活动影响方面的效用取决于对特定扰动驱动的变化预测的准确性。这种准确性主要由反馈模拟的好坏来控制。esm预测变化的准确性尚不清楚，因为以前的模式验证仅限于评估当前条件的再现程度，或将古气候模式结果与稀疏且可能模糊的代理数据进行比较。为了对ESM性能进行更彻底的评估，将比较历史时间尺度上已知扰动引起的模型预测和观测变化。在本研究中，咸海的人为干旱化将被用作区域ESM（与国家大气研究中心相关的RegCM2和湖泊模式）预测精度的测试，该模型包括一个相互耦合的大气和湖泊。自1960年以来，咸海的干旱化是由于周围盆地为集中灌溉而引水引起的，其范围之广足以产生区域性气候反应。这种程度的干燥也应该产生模型响应。重要的是。有跨越干旱期的气象和水文观测资料，因此可以对实际变化进行量化。将通过比较模式模拟的变化与1960年至1995年间观测到的变化来检验模式的预测能力。这项工作由三个部分组成。首先，观测结果将用于量化可能由咸海干燥引起的区域气候和湖泊水文变化。这些观测到的变化将用于(i)测试模型预测，（ii）直接测量咸海的存在如何改变区域气候，（iii）直接测量湖泊水位变化如何影响咸海的水文，以及（iv）量化区域尺度的人类影响。其次，通过比较模拟和观测的干旱化区域气候和湖泊水文变化，评估regcm2 -湖泊交互耦合模式在预测变化方面的优势和不足。为了更深入地了解耦合模式成功和失败的原因，还将评估RegCM2和湖泊模式在气象或水文观测驱动下的独立（非交互）版本的预测精度。第三，计算咸水对不同表面积、深度和盐度海域的区域气候效应。这将允许：(i)量化湖泊与大气的相互作用和与湖泊水位变化有关的反馈；（ii）预测咸海进一步人为干旱化驱动的未来气候变化；（iii）评估模式预测的在干燥前期和现在和现在之间的变化有多少是由于大规模气象变率造成的。将根据所确定的模式的优点和缺点，编制和评估由额外干燥引起的未来气候变化的预测。这项研究很重要，因为它试图测试耦合的区域气候湖泊模型如何预测人类活动对大型浅终端湖泊的影响，以及这种影响如何反馈到区域和全球气候。

Abstract ATM-9632304 Sloan, Lisa C. University of California, Santa Cruz Title: Modeling Anthropogenic Desiccation of the Aral Sea: A Unique Test of the Predictive Capabilities of a Regional Earth System Model The utility of global and regional earth system models (ESMs) for investigating causes of past climate change, and predicting impacts of future human activities, depends on how accurately changes driven by specific perturbations are predicted. This accuracy is controlled primarily by how well feedbacks are simulated. The accuracy of ESM-predicted changes is unknown, because previous model validation has been limited to assessing how well present conditions are reproduced or comparing paleoclimate model results with sparse and potentially ambiguous proxy data. In order to conduct a more thorough evaluation of ESM performance, model- predicted and observed changes resulting from known perturbations over historical timescales will be compared. In this study, anthropogenic desiccation of the Aral Sea will be used as a test of the predictive accuracy of a regional ESM (the RegCM2 and lake model associated with the National Center for Atmospheric Research) that includes an interactively coupled atmosphere and lake. Desiccation of the Aral Sea since 1960, resulting from diversion of water for intensive irrigation in the surrounding basin, has been extensive enough to produce a regional climatic response. Desiccation of this magnitude should also produce a model response. Importantly. meteorological and hydrologic observations that span the interval of desiccation are available so the actual changes can be quantified. The predictive capabilities of the model will be tested by comparing model-simulated changes with observed changes that have occurred between 1960 and 1995. The work consists of three components. First, observations will be used to quantify regional climate and lake hydrologic changes that are likely due to Aral Sea desiccation. These obser ved changes will be used to (i) test model predictions, (ii) directly measure how the presence of the Aral Sea alters regional climate, (iii) directly measure how lake-level variations have impacted the Aral Sea's hydrology, and (iv) quantify regional-scale human impacts. Second, the interactively coupled Reg CM2-lake model's strengths and weaknesses in predicting changes will be assessed, by comparing simulated and observed desiccation-induced regional climate and lake hydrologic changes. In order to gain a more thorough understanding of the causes for the coupled model's successes and failures, the predictive accuracy of independent (non-interactive) versions of RegCM2 and the lake model, driven by meteorological or hydrologic observations, will also be evaluated. Third, the regional climate effects generated by the Aral for seas of different surface area, depth and salinity will be calculated. This will allow: (i) quantification of lake-atmosphere interactions and feedbacks associated with lake-level variations; (ii) prediction of future climate changes driven by further anthropogenic Arals Sea desiccation; and (iii) assessment of how much of the model predicted change between pre- desiccation and -present and present intervals was due to large-scale meteorological variability. Predictions of future climate changes resulting from additional desiccation will be prepared and evaluated in terms of the model's strengths and weaknesses as determined. This research is important because it seeks to test how well coupled regional climate lake models predict the impact of human activities on a large shallow terminal lake and how that feedbacks on the regional and global climate.