Assessing the Oceanic Water Cycle with an Integrative Approach

采用综合方法评估海洋水循环

• 批准号: 0647949
• 负责人: Raymond Schmitt
• 金额: $ 79.13万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-15 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0647949&HistoricalAwards=false
• 关键词: Assessing; Oceanic; Water; Cycle; Integrative

ABSTRACTOCE-0647949Though many programs purport to study the global water cycle, none have properly addressed its largest component, the oceans. The oceans are by far the largest reservoir of water on Earth, the source of most evaporation and the sink of most precipitation. Trends in ocean salinities over the past 40 years provide indications of a changing global water cycle. However, quantitative assessment of the water cycle over the vast oceanic areas remains challenging because of the scarcity of data. In this study, a support is requested to utilize data from new ocean flux climatologies, river flow data, growing oceanic salinity monitoring networks and an assimilative global ocean circulation model to examine the mean state, seasonal cycle, trends and variability in the water cycle over the global ocean.Intellectual impact: It is generally assumed that global warming will enhance the water cycle, due to the greater vapor carrying capacity of warmer air. The vapor pressure of water is about 15mb at the mean global temperature of 14oC and increases about 1mb/oC at this temperature. Thus, a 1oC temperature rise may enhance the water cycle by ~ 7%, assuming transport by the wind is not changed dramatically. This is about 10cm/year for an evaporation minus precipitation (E-P) difference of 1.5m/yr. This is the sort of evaporation increase inferred from salinity trends in the subtropical Atlantic over the past 40 years. The suggested integrative approach combines new flux data and a data assimilating ocean circulation model to address the following four general issues regarding the oceanic water cycle:(1) What are the mean and seasonal patterns of net water exchange between atmosphere, ocean and land? What meridional fluxes and inter-basin transports of freshwater are implied for the oceans? (2) What are the consequences of river water discharges vs. rainfall for upper ocean thermohaline structure? What changes in upper-ocean mixing result from evaporative or precipitative forcing and how does upper ocean mixing affect the oceans ability to absorb, store, transport and release heat and freshwater? What pathways and timescales are found for salinity anomalies generated by surface flux changes? How do these feedback on climate?(3) What are the seasonal and interannual variations in the land and ocean storage of freshwater and how do these affect the upper-ocean salinity distribution? Are changes in evaporation and rainfall due to variations in winds patterns, SST, or atmospheric humidity?(4) Which regions of the ocean show the most sensitive and interesting response to freshwater forcing? Which regions would be best for an ocean/atmosphere process study during the upcoming Aquarius salinity satellite mission (2009 launch)?Broader impacts: Advancing our understanding of the water cycle will be of great benefit to society, as anticipation of trends in water supplies is fundamental for planning allocation of water resources. The ocean is key to this understanding; the addition of only one percent of Atlantic rainfall would double the discharge of the Mississippi river. This project will develop ties between oceanographers, surface flux experts and modelers to study the ocean-atmosphere-land exchanges of freshwater for the global ocean. Any knowledge gained will improve our understanding of the water cycle, and its effects on the ability of the ocean to absorb, store and transport heat. Thus, an improved understanding of this key component of the climate system will be achieved, thereby leading to greater chances of predicting future changes. Finally, the training of one graduate student in this important area will be supported, and a web site on the oceanic water cycle and help identify likely sites for salinity constrained ocean-atmosphere exchange process studies will be developed.This Project is a contribution to the U.S. CLIVAR (CLImate VARiability and predictability) Program.

ABSTRACTOCE-0647949 尽管许多项目都旨在研究全球水循环，但没有一个项目能够正确解决其最大的组成部分——海洋。海洋是迄今为止地球上最大的水库、大部分蒸发的来源和大部分降水的汇。过去 40 年海洋盐度的趋势表明了全球水循环的变化。然而，由于数据缺乏，对广阔海洋区域水循环的定量评估仍然具有挑战性。在这项研究中，请求支持利用来自新的海洋通量气候学、河流流量数据、不断增长的海洋盐度监测网络和同化全球海洋环流模型的数据来检查水循环的平均状态、季节周期、趋势和变化。全球海洋。学术影响：人们普遍认为，全球变暖将增强水循环，因为温暖的空气具有更大的水蒸气承载能力。在全球平均温度 14oC 时，水的蒸气压约为 15mb，并在此温度下增加约 1mb/oC。因此，假设风的输送没有发生显着变化，温度升高 1°C 可能会使水循环增强约 7%。对于 1.5m/年的蒸发减降水 (E-P) 差异，这大约为 10cm/年。这是根据过去 40 年亚热带大西洋盐度趋势推断出的蒸发量增加情况。建议的综合方法结合了新的通量数据和同化海洋环流模型的数据，以解决有关海洋水循环的以下四个一般问题：（1）大气、海洋和陆地之间净水交换的平均和季节模式是什么？海洋意味着什么经向通量和跨流域淡水输送？ (2) 河水排放量与降雨量对海洋上层温盐结构有何影响？蒸发或降水强迫会导致上层海洋混合发生哪些变化？上层海洋混合如何影响海洋吸收、储存、运输和释放热量和淡水的能力？地表通量变化产生的盐度异常有哪些途径和时间尺度？这些对气候的反馈如何？（3）陆地和海洋淡水储存的季节和年际变化是什么？这些如何影响上层海洋盐度分布？蒸发和降雨量的变化是由于风型、海表温度或大气湿度的变化造成的吗？(4) 海洋的哪些区域对淡水强迫表现出最敏感和最有趣的反应？在即将到来的水瓶座盐度卫星任务（2009 年发射）期间，哪些地区最适合进行海洋/大气过程研究？ 更广泛的影响：加深我们对水循环的了解将对社会大有裨益，因为对供水趋势的预期正在不断变化。是水资源规划配置的基础。海洋是实现这一理解的关键。仅增加大西洋降雨量的百分之一，密西西比河的流量就会增加一倍。该项目将发展海洋学家、表面通量专家和建模者之间的联系，以研究全球海洋淡水的海洋-大气-陆地交换。获得的任何知识都将增进我们对水循环及其对海洋吸收、储存和运输热量能力的影响的理解。因此，将更好地了解气候系统的这一关键组成部分，从而有更大的机会预测未来的变化。最后，将支持在这一重要领域培训一名研究生，并将开发一个有关海洋水循环的网站，并帮助确定盐度约束海洋-大气交换过程研究的可能地点。该项目是对美国 CLIVAR（气候变异性和可预测性）计划。