Field data reconstruction and upper ocean circulation variability in tropical Indo-Pacific
| Author(s) | Meng, Lingsheng | |
| Date Accessioned | 2023-03-16T12:57:41Z | |
| Date Available | 2023-03-16T12:57:41Z | |
| Publication Date | 2022 | |
| SWORD Update | 2023-02-14T17:07:11Z | |
| Abstract | Observations are fundamental for studying and understanding the oceans. While in-situ measurements are limited, satellites can remotely monitor the ocean continuously for extended periods with broad spatial coverages. Thus, they have been providing large and ever-growing data volumes. However, most remote-sensed products are the surface ocean. Despite the shortage of observations, many important processes and features at subsurface and interior oceans need to be detected and studied (e.g., subsurface temperature, density, internal waves and tides, subsurface flows). Consequently, the techniques of constructing subsurface and deep oceans from surface ocean have been developed, i.e., using ocean surface data to reconstruct ocean interior data based on their relationships. Since the data are mostly from remote sensing, they are also known as deep ocean remote sensing (DORS) techniques. Here I developed some data-driven models to estimate ocean subsurface and interior variables from satellite-observed sea surface data by using deep learning methods. A higher resolution (1/4 degree) temperature and salinity (T and S) field data is constructed based on the Argo gridded data (1 degree); while, A super resolution (1/12 degree) T and S field data is constructed based on the reanalysis data. Dynamic height fields and the associated ocean geostrophic flows are also calculated and analyzed. This work enriches oceanic observations with respect to vertical dimension and horizontal resolution, which can largely make up for the paucity of the subsurface and deep ocean observation, and further facilitate the studies of ocean circulation, ocean dynamics, and climate changes. ☐ Ocean circulation transports water mass and redistributes heat, saline, and nutrients in the oceans. Therefore, determining the changes in ocean circulation is essential to understand ocean states and processes and to predict climate change. Upper ocean holds the major and most ocean circulation changes compared with deeper oceans, because wind and heat and water fluxes that mainly driven ocean circulation occur at ocean surface. Pacific Ocean and Indian Ocean are closely connected and they together are called Ind-Pacific oceans. Considering the importance and complexity, upper ocean circulation variability in tropical Indo-Pacific needs to be explored in detail, from different scales and from different perspectives. ☐ Sea level changes within wide temporal-spatial scales have great influence on oceanic and atmospheric circulations. Many previous works have identified long-term sea level change, while regional sea level variations on different time scales. Sea level change on interannual and decadal time-scales needs more studies. Here, sea level anomaly (SLA) was decomposed into interannual and decadal time-scales. The temporal-spatial features of the SLA variability in the Pacific have been examined and associated with climate variability modes. Moreover, decadal SLA oscillations in the Pacific Ocean were identified during 1993-2016, with the phase reversals around 2000, 2004, and 2012. In the tropical Pacific, large sea level variations in the western and central basin were a result of changes in the equatorial wind stress. Furthermore, coherent decadal changes could also be seen in wind stress, sea surface temperature (SST), subtropical cells (STCs) and thermocline depth. ☐ The shallow overturning circulation is a wind-driven circulation in the tropical region, adjusting water mass and heat in 3-dimension. This study investigates the Indian Ocean (IO) shallow overturning circulation during 1958-2017. Their structure consists of a cross-equator cell (CEC) and a southern subtropical cell (SSTC). Both the CEC and the SSTC exhibited significant variability on interannual to decadal timescales during 1958-2017, and this variability mainly resulted from changes in both meridional Ekman transports and meridional geostrophic flows in the upper layer; each component could dominate the shallow cells’ variations in certain years. This work presents a comprehensive study of the interannual to decadal variability of the IO shallow cells and the corresponding reasons and influences and tried to link these variations with other variations in the IO. | |
| Advisor | Yan, Xiao-Hai | |
| Degree | Ph.D. | |
| Department | University of Delaware, School of Marine Science and Policy | |
| DOI | https://doi.org/10.58088/zyfe-sz61 | |
| Unique Identifier | 1373092729 | |
| URL | https://udspace.udel.edu/handle/19716/32455 | |
| Language | en | |
| Publisher | University of Delaware | |
| URI | https://login.udel.idm.oclc.org/login?url=https://www.proquest.com/dissertations-theses/field-data-reconstruction-upper-ocean-circulation/docview/2778586889/se-2?accountid=10457 | |
| Keywords | Data reconstruction | |
| Keywords | Indo-Pacific oceans | |
| Keywords | Ocean circulation | |
| Keywords | Tropical oceans | |
| Title | Field data reconstruction and upper ocean circulation variability in tropical Indo-Pacific | |
| Type | Thesis |