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Impact of Climate Variation and Huma...

Du, Jiabi.

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Impact of Climate Variation and Human Adaptation on the Physical Transport Processes and Water Exchange in Chesapeake Bay.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Impact of Climate Variation and Human Adaptation on the Physical Transport Processes and Water Exchange in Chesapeake Bay./
作者:	Du, Jiabi.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
面頁冊數:	250 p.
附註:	Source: Dissertation Abstracts International, Volume: 79-01(E), Section: B.
Contained By:	Dissertation Abstracts International79-01B(E).
標題:	Physical oceanography. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10608487
ISBN:	9780355139426

Impact of Climate Variation and Human Adaptation on the Physical Transport Processes and Water Exchange in Chesapeake Bay.
Du, Jiabi.

Impact of Climate Variation and Human Adaptation on the Physical Transport Processes and Water Exchange in Chesapeake Bay. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 250 p.

Source: Dissertation Abstracts International, Volume: 79-01(E), Section: B.

Thesis (Ph.D.)--The College of William and Mary, 2017.

The efficiencies of water exchanges in both vertical and horizontal directions reflect the overall impact of various physical processes and serve as important indicators of physical control over a variety of ecological and biogeochemical processes. The vertical exchange between surface layers and bottom layers of a waterbody has proved to exert great control over the hypoxic condition, while the horizontal exchange between an estuary and coastal ocean determines the flushing capacity of the estuary and the retention rate of riverine materials. Various processes, such as tidal flushing, tidal mixing, gravitational circulation, and lateral circulation, can affect water exchange. Therefore, water exchange processes are complex and varying in time and space in estuaries. Besides the impact of numerous forcing variables, large-scale climate oscillation, sealevel rise, and human activities can result in a change of estuarine dynamics. Two biologically relevant timescales, residence time (RT) and vertical exchange time (VET), are used in this study to quantify the overall horizontal and vertical exchange, aiming to understand the physical transport control over the ecosystem functioning in a simpler way.

ISBN: 9780355139426Subjects--Topical Terms:

3168433
Physical oceanography.

Impact of Climate Variation and Human Adaptation on the Physical Transport Processes and Water Exchange in Chesapeake Bay.
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245 1 0 $a Impact of Climate Variation and Human Adaptation on the Physical Transport Processes and Water Exchange in Chesapeake Bay.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 250 p.
500 $a Source: Dissertation Abstracts International, Volume: 79-01(E), Section: B.
500 $a Adviser: Jian Shen.
502 $a Thesis (Ph.D.)--The College of William and Mary, 2017.
520 $a The efficiencies of water exchanges in both vertical and horizontal directions reflect the overall impact of various physical processes and serve as important indicators of physical control over a variety of ecological and biogeochemical processes. The vertical exchange between surface layers and bottom layers of a waterbody has proved to exert great control over the hypoxic condition, while the horizontal exchange between an estuary and coastal ocean determines the flushing capacity of the estuary and the retention rate of riverine materials. Various processes, such as tidal flushing, tidal mixing, gravitational circulation, and lateral circulation, can affect water exchange. Therefore, water exchange processes are complex and varying in time and space in estuaries. Besides the impact of numerous forcing variables, large-scale climate oscillation, sealevel rise, and human activities can result in a change of estuarine dynamics. Two biologically relevant timescales, residence time (RT) and vertical exchange time (VET), are used in this study to quantify the overall horizontal and vertical exchange, aiming to understand the physical transport control over the ecosystem functioning in a simpler way.
520 $a A long-term simulation of VET in the Chesapeake Bay over the period of 1980- 2012 revealed a high spatial and seasonal similarity between VET and the dissolved oxygen (DO) level in the mainstem of the Chesapeake Bay, suggesting a major control over the DO condition from the physical transport. Over the past three decades, a VET of about 20 days in the summer usually indicates a hypoxic condition in the mainstem. Strong correlation among southerly wind strength, North Atlantic Oscillation index, and VET demonstrates that the physical condition in the Chesapeake Bay is highly controlled by the large-scale climate variation. The relationship is most significant during the summer, during which time the southerly wind dominates throughout the Chesapeake Bay. By combining the observed DO data with modeled VET, decoupling the physical and biological effect on the DO condition becomes possible. Bottom DO consumption rate was estimated through a conceptual model that links DO with VET. Using observed DO data and modeled VET, the overall biological effect on the DO condition can be quantified. The estimated bottom DO consumption rate shows strong seasonal variation and its interannual variation is highly correlated with the nutrient loading.
520 $a The response of an estuary ecosystem to a change of nutrient loading depends on the flushing capacity of the estuary, which is related to the horizontal water exchange. The overall flushing capacity can be quantified by resident time, which determines the retention and export rates of materials discharged in the estuary. The horizontal exchange in Chesapeake Bay was investigated over the period of 1980-2012. Quantified by the residence time (RT), the horizontal exchange in Chesapeake Bay exhibits high interannual and spatial variability. The 33-year simulation results show that the mean RT of the entire Chesapeake Bay system ranges from 110 to 264 days, with an average value of 180 days, which is smaller than 7.6 months (approximately 230 days) reported in previous studies. There is significant lateral asymmetry of RT in the mainstem, with a larger RT along the eastern bank than that along the western bank in the lower Bay, which is mainly attributed to the horizontal shearing of estuarine circulation and large freshwater input along the western bank. Because of the persistent stratification and estuarine circulation, the vertical difference between the surface RT and bottom RT is dramatic, with a difference as large as 100 days. Relations among RT, river discharge, and strength of estuarine circulation reveal that the variation of horizontal exchange is mainly controlled by the river discharge and modulated by the estuarine circulation. A strengthened estuarine circulation will enhance the water exchange and reduce the RT. By affecting the estuarine circulation, wind forcing has a great impact on the horizontal exchange. (Abstract shortened by ProQuest.).
590 $a School code: 0261.
650 4 $a Physical oceanography. $3 3168433
690 $a 0415
710 2 $a The College of William and Mary. $b Marine Science. $3 3282735
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791 $a Ph.D.
792 $a 2017
793 $a English
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