The coupled surfzone and inner-shelf heat budget: The effect of albedo, surface gravity, and internal waves

GSTDTAP

项目编号	1558695
	The coupled surfzone and inner-shelf heat budget: The effect of albedo, surface gravity, and internal waves
	Falk Feddersen
主持机构	University of California-San Diego Scripps Inst of Oceanography
项目开始年	2016
	2016-03-01
项目结束日期	2019-02-28
资助机构	US-NSF
项目类别	Standard Grant
项目经费	291617(USD)
国家	美国
语种	英语
英文摘要	Nearshore waters are of critical economic and ecological importance. A wide variety of species including invertebrates (clams, crabs, mollusks), fish, and birds make their home and forage in this region. Coasts are also centers of tourism and recreation, fueling economic activity. Water temperature is known to be highly variable here in space and over time, playing a critical role in many components of nearshore ecosystems. In the deeper water of the continental-shelf (depths 12-100 m) heat budget has been extensively studied and the cross-shelf export of heat has been quantified. However, in shallower water, the coupled heat budget of the surfzone (where the shallow depth causes wave breaking) and the inner-shelf just offshore has not been studied. Thus, the processes that drive nearshore temperature variability are poorly understood and unique physical processes that affect this region?s heat budget have not been considered. This project will use data from a new 9-month field experiment that resolved the thermal structure from the shoreline to 6m water depth to characterize key processes that drive temperature variability in the nearshore such as heat transfer by rip currents, mixing by breaking internal waves, local heat generation upon the dissipation of gravity wave energy, and the reflection of solar energy by foam and bubbles due to breaking waves. Analysis of these unique data will improve understanding of the physical processes governing temperature (heat) evolution that can be applied to the broad range of economically and ecologically important nearshore regions. This work will have application to nonlinear internal wave transformation and related mixing. Nearshore temperature evolution and cross-shore fluxes are tightly linked to the ecology of bacterial pathogens, diatoms, larvae, and invertebrates in this region. Elevated surfzone albedo may explain surfzone persistence of harmful pathogens, with human health implications. This work will also have implications for internal wave driven larval transport into and across the nearshore. Research and education will be integrated at all academic levels. This project will train a PhD student who was involved in all aspects of the field work. An outreach collaboration will be developed with an AP Environmental Science class at the underserved Kearny Science High School, developing curriculum materials, teaching lectures, and hosting a field trip. Undergraduate students will be engaged through the SIO REU program. Although nonlinear internal-wave driven nearshore temperature variability has previously been observed at a single location, the full cross-shore, vertical, and temporal variability of the coupled surfzone and inner-shelf has yet to be characterized. A pilot surfzone heat budget showed that a full coupled surfzone inner-shelf heat budget was feasible and that surface gravity wave energy flux heated the surfzone at a rate on average a quarter of the solar radiation, indicating its importance to the heat budget. A new 9-month long field experiment on the Scripps Institution of Oceanography (SIO) pier, designed to close the coupled surfzone/inner-shelf heat budget, has just been completed. The experiment, executed by 3rd year graduate student Greg Sinnett, highly resolved the spatio-temporal structure of temperature from the shoreline to 6-m water depth over almost a full seasonal cycle. In addition, 3 ADCP current meters were deployed to measure advective heat fluxes and a pier-deployed 4-way radiometer was deployed to measure surfzone and inner-shelf albedo. These extensive new field observations will be analyzed to close a coupled surfzone and inner-shelf heat budget and quantify the magnitude and variability of the heat budget terms. In particular, this region has unique processes influencing the heat budget that have yet to be considered or properly quantified. The surfzone albedo (due to foam or whitewater) may be significantly elevated over open ocean albedo, thereby reducing surfzone solar heating. However, surfzone albedo has not been quantified and the factors influencing it are not understood. This study will quantify surfzone albedo, determine its importance in reducing surfzone incident solar radiation, and develop albedo parameterizations. The pilot surfzone heat budget found that surface gravity wave heating was important relative to solar radiation during summer when waves are small and days long. This analysis will quantify the relative importance of wave heating from late summer to early spring. In the pilot study, advective heat flux was inferred (not measured) to drive significant temperature variability and on average cool the surfzone. Two physical mechanisms driving heat fluxes are nonlinear internal waves and rip currents. The observations will be used to quantify the advective heat flux across the nearshore, its magnitude and time-scales, and examine the mechanisms driving it, and potential feedbacks with incident waves or barotropic tides. Thus, the project will provide a detailed understanding of the processes governing nearshore temperature variation and will allow for the parameterization of some of these processes.
来源学科分类	Geosciences - Ocean Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/69192
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Falk Feddersen.The coupled surfzone and inner-shelf heat budget: The effect of albedo, surface gravity, and internal waves.2016.