Effect of tides on river water behavior over the eastern shelf seas of China
Effect of tides on river water behavior over the eastern shelf seas of China
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DOI：
10.5194/hess-26-5207-2022
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发表时间：
2022-10
影响因子：
6.3
通讯作者：
Lei Lin;Hao Liu;Xiaomeng Huang;Qingjun Fu;Xinyu Guo
中科院分区：
文献类型：
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作者：
Lei Lin;Hao Liu;Xiaomeng Huang;Qingjun Fu;Xinyu Guo
摘要。河流将大量淡水和陆源物质带入陆架海，陆架海是全球水循环和生物地球化学循环的重要组成部分。地球系统模式或气候模式是模拟和预测全球水循环和气候变化的重要工具，但潮汐通常被去除。为了更好地理解不考虑潮汐对水循环模拟的潜在影响，本研究比较了考虑和不考虑潮汐的区域模式的结果，并从输送途径、时间尺度和水浓度的角度评估了潮汐对中国东部陆架海三条主要河流（黄江、鸭绿江和长江）水行为的影响。结果表明：潮汐对黄江、鸭绿江的输运较为分散，而对长江的输运较为集中；潮汐对黄河、鸭绿江和长江过境区的影响分别为13%、40%和21%。在有潮汐模式下，三条河流的年平均水龄和过境时间比无潮汐模式高几倍（~ 2-10），表明潮汐显著减缓了河流在大陆架上的输水和出水率。潮汐减缓了河水输出，导致河水浓度增加了3倍，陆架海水盐度降低了100万立方米。此外，潮汐对河流行为的影响在相对封闭的海（如渤海和黄海）比在相对开放的海（如东海）更强。潮汐引起的陆架流的变化是两种模式间河水行为差异的主要原因。潮汐可以增加海底应力，从而削弱陆架洋流，减少水输送的时间尺度。无潮模型对潮汐参数化的改进非常有限。考虑到河流径流对全球水循环的重要作用以及河流水行为变化对海洋碳循环的影响，将潮汐效应纳入地球系统模型以提高模型的预测精度非常重要。
Abstract. Rivers carry large amounts of freshwater and terrestrial material into shelf seas, which is an important part of the global water and biogeochemical cycles. The earth system model or climate model is an important instrument for simulating and projecting the global water cycle and climate change, in which tides however are commonly removed. For a better understanding of the potential effect of the absence of tides in the simulation of the water cycle, this study compared the results of a regional model with and without considering tides, and evaluated the effect of tides on the behavior of three major rivers (i.e., the Yellow, Yalujiang, and Changjiang rivers) water in the eastern shelf seas of China from the perspectives of transport pathways, timescales, and water concentration. The results showed that the tides induced more dispersed transport for the water of the Yellow and Yalujiang rivers, but more concentrated transport for the Changjiang River water. The effect of tides on the transit areas of the Yellow, Yalujiang, and Changjiang rivers was 13 %, 40 %, and 21 %, respectively. The annual mean water age and transit time of the three rivers in the model with tides were several (∼ 2–10) times higher than those in the no-tide model, suggesting that tides dramatically slow the river water transport and export rate over the shelf. By slowing the river water export, tides induced a three-fold increase in river water concentration and a decrease in shelf seawater salinity by > 1. Moreover, the effect of tides on river behavior was stronger in relatively enclosed seas (i.e., the Bohai and Yellow seas) than in relatively open seas (i.e., the East China Sea). The change in the shelf currents induced by tides is the main cause of the difference in the river water behavior between the two model runs. Tides can increase bottom stress and thus weaken shelf currents and decrease the water transport timescales. The improvement in tidal parameterization in the no-tide model in the simulation of river water behavior was very limited. Given the important role of river runoff on the global water cycle and the effect of changes in river water behavior on ocean carbon cycling, it is important to include the tidal effect in earth system models to improve their projection accuracy.