The impact of warmer sea surface temperatures on gross primary production in the Southeast Asian Region | |
| Author | Chalermpol Wangsomcholk |
| Call Number | AIT Diss no.CC-23-01 |
| Subject(s) | Ocean temperature--Pacific Ocean Primary productivity (Biology)--Southeast Asian Climatic changes |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of doctor of Philosophy in Climate Change and Sustainable Development |
| Publisher | Asian Institute of Technology |
| Abstract | The impacts of elevated sea surface temperatures (SSTs) on aquatic biomes have been extensively studied, leading to a wealth of knowledge in this area. However, the scope of research in understanding the implications of augmented sea surface temperatures on terrestrial ecosystems—more precisely, the impacts on biomass production—has been largely underexplored in the existing scientific literature. Such an investigation has the potential to unearth a hitherto unexplored chain reaction set off by radiative forcing, which might render a more complete grasp of the wide-ranging influences of climate change. The principal aim of this investigation is to elucidate the potential implications of an elevated SST in the Western Pacific Ocean (WPO) on terrestrial gross primary production (GPP) within the Southeast Asian (SEA) region. The supposition driving this inquiry is that precipitation might serve as the most consequential conduit connecting these two variables. To achieve the specified goal, an array of statistical methods was utilized, which included correlation studies, time-series analysis, and regression evaluations. These methods were applied to relevant arrays of data gathered through remote sensing. The research utilized five essential remote sensing information datasets, spanning from 2002 to 2020: the Level 4 Multiscale Ultrahigh Resolution High-Resolution Sea Surface Temperature, the Global Precipitation Measurement facilitated by Integrated Multi-satellitE Retrievals, MOD17A2H which represents Gross Primary Productivity, ESA CCI Soil Moisture dataset, and the MCD12Q1 dataset that pertains to land cover. This investigation reveals that the linkage between the WPO's SST and the GPP in the SEA region might not be strikingly substantial nor significantly dependent, yet it persists as complex, extending beyond the basic principles of evaporation and photosynthesis. The complexity stems from the indirect connection between SSTs, a marine phenomenon, and GPP, a terrestrial event. Intermediate mechanisms, such as the formation of warm pools by trade winds, moisture transport from sea to land, and soil water retention for plant use, bridge the gap between these systems and contribute to the complexity of their relationship. Additionally, the non-uniform or imperfect functioning of these mechanisms, particularly those responsible for moisture transfer to the SEA landmass, introduces an additional layer of complexity. While significant trends can still be observed, the inherent variability hinders definitive predictions regarding the nature of SST-GPP interactions, thus introducing intrinsic uncertainties. Nonetheless, it is feasible—in an estimative capacity—to pinpoint crucial terrestrial and marine areas—through the deployment of statistical methodologies— manifesting a marked inclination towards significance in the SST- GPP interrelation. The derived results illuminate that escalated SSTs in the marine zone encompassing 0 – 20°N latitude and the longitudinal expanse of 120°E - 150°E manifest a notable correlation with intensified precipitation in the northern segment of SEA (from 0 latitude to approximately 25°N). Alternatively, augmented SSTs within oceanic areas defined by 0 – 20°S latitude and a longitudinal range from 120°E to 180°E display a significant correlation with enhanced precipitation in the southern segment of SEA (from 0 latitude to roughly 10°S). The result also suggests that this correlation is especially noticeable within the southern regions of Southeast Asia, as compared to the northern areas. This assertion is buttressed by the evidence indicating that the annual rainfall across most of southern SEA can escalate from approximately 1,600 mm to roughly 4,000 mm in response to a modest SST increase from 28.06°C to 28.70°C. Conversely, in a majority of the northern counterpart, an elevation in SSTs from 28.72°C to 29.5°C leads to an inconsequential surge in yearly precipitation, rising from about 1,400 mm to approximately 2,000 mm. The potential rationale for this divergence could relate to the proximity between terrestrial and marine regions; the southern SEA is considerably closer to the key oceanic area in comparison to its northern counterpart. Despite the observed pronounced influence of elevated SST on precipitation within certain SEA locales, this increment in SST-induced rainfall does not - in the majority of instances - substantially influence GPP (or directly translate into a GPP enhancement), given the limitations dictated by the soil's capacity for water retention, which nearly always saturates at approximately 0.35 m3 /m3 . This investigation contributes meaningful advancements in understanding the terrestrial impacts of marine phenomena under climate change, enhancing regional climate model accuracy. By rigorously mapping key terrestrial and marine regions influencing Southeast Asia's rainfall and GPP in relation to WPO's SSTs, the research enables more precise predictions of climate patterns. Moreover, it illuminates the complex, non-linear interplay between rainfall, soil moisture dynamics, and GPP across diverse biomes, especially under conditions of escalating SSTs. This nuanced understanding paves the way for more resilient climate strategies by considering ecological and hydrological responses. Thus, the study's findings are instrumental for developing sophisticated climate models, leading to improved climate resilience and management strategies. |
| Year | 2023 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Climate Change and Sustainable Development (CC) |
| Chairperson(s) | Shrestha, Rajendra Prasad |
| Examination Committee(s) | Sarawut Ninsawat;Ekbordin Winijkul |
| Scholarship Donor(s) | Royal Thai Government Fellowship;Asian Institute of Technology Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2023 |