CAREER: Understanding the Role of Oceans in the Planetry Energy Budget

职业：了解海洋在地球能源预算中的作用

• 批准号: 1455071
• 负责人: Brian Rose
• 金额: $ 54.47万
• 依托单位: SUNY at Albany
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1455071&HistoricalAwards=false
• 关键词: CAREER; Understanding; Role; Oceans; Planetry

This is a CAREER proposal in which the research goal is to understand the roles of ocean heat transport (OHT) and ocean heat uptake (OHU) in the planetary energy budget. Here OHU refers to the transfer of heat from the ocean surface to depths at which the heat no longer longer affects the overlying atmosphere, thus effectively removing heat from the surface climate for a period of years to decades or longer. OHT refers to heat transport in which heat is removed from the surface in one region, transported by the subsurface ocean, and resurfaces in another. The role of OHU in climate change has become a topic of some interest, as increased OHU could explain the hiatus in global warming following the end of the 20th century. Further motivation for the project comes from modeling studies showing that different spatial patterns of OHU can cause different amounts of global warming suppression, even when the total heat uptake is the same. To some extent these differences can be explained in terms of regional climate feedbacks. For example the sea ice albedo feedback can play a significant role in amplifying the global warming caused by greenhouse gas (GHG) increases, but sea ice only occurs in cold regions near the poles. Removal of surface heat from high latitudes by OHU or OHT could reduce GHG-induced warming in these regions and thus reduce the amplifying effect of the sea ice albedo feedback. But previous work by the PI and others suggests that the effects of OHU and OHT cannot be entirely explained in terms of regional climate feedbacks activated to a greater or lesser extent depending on how the oceans redirect heat. In addition, the effects of OHU and OHT cannot be understood without considering the role of atmospheric energy transport. A previous study found that if OHU removes heat from the tropical oceans (or if OHT transfers heat out of the tropics), atmospheric transport of moist static energy will be quite efficient in spreading the effect beyond the tropics and evenly cooling the globe. But an equivalent heat removal in high latitudes instead produces concentrated high latitude cooling, a difference which can be explained in terms of the strong background moisture contrast between the warm tropics and the cold poles. The work is primarily concerned with the ocean's role in current and future climate change, but it will also consider the role of OHT in producing past climates in which the temperature contrast between low and high latitudes was reduced, such as occurred in the Phanerozoic and early Eocene. The research will also consider the response of the hydrological cycle to OHU and OHT, with a focus on the subtropics. Past work suggests that while global warming simulations often find subtropical drying, subtropical warming due to OHT can produce the opposite effect. Thus OHT could counteract GHG-induced drying to the extent that heat absorbed by the tropical oceans is transported to the subtropics, a potentially relevant effect given recent results relating the warming hiatus to OHU in the equatorial Pacific.The research agenda for the project has two key components. First, much of the work will be conducted using simplified climate models in which the ocean component model is replaced by a "slab ocean", which can absorb heat and interact thermally with the atmosphere, but which cannot transport heat. In this context heat OHT and OHU are externally imposed in the form of heat sources and sinks applied to regions where OHT converges and diverges, and where heat is sequestered in the deep ocean. Such external forcing is commonly used and is generally referred to as Q-flux forcing. The experiments allow the feedbacks and atmospheric transports to be examined in isolation, without the complications introduced by an interactive ocean. Second, the results of such experiments are often model dependent, and thus an ensemble of models is required to determine which aspects of the response to imposed OHT and OHU forcing are robust. To address this issue, the PI will organize a model intercomparison project (MIP), in which a common set of experiments will be performed using several different models. Some experiments will be performed by the PI, but he will also solicit contributions to the MIP by other researchers. Further research will include an examination of global warming simulations from state-of-the-art climate models in the Coupled Model Intercomparison Project version 5 (CMIP5), as well as perturbed physics sensitivity experiments with a single slab ocean climate model.The educational component of this CAREER project is centered on the development of a flexible climate modeling and analysis package in the Python language. The educational activity is intended to address the lack of computing skills commonly found among undergraduate and graduate students enrolled in atmospheric science departments. Specific tasks are 1) to develop a short introductory course in practical scientific computing in the Python language; 2) to develop a modular Python-based climate modeling and analysis toolkit; and 3) to develop a series of interactive educational modules illustrating fundamental principles of climate and atmospheric science. Several factors motivate the choice of Python as the language of choice, including its inherent modularity, its ability to serve as a "wrapper" for compiled Fortran and C codes, thereby promoting seamless use of established codes, and the numerous visualization and software development tools available for the language. The software to be developed will be open source, freely available online, and well documented. It will consist of a number of simplified dynamical core and process models (for radiative transfer, boundary layer turbulent fluxes, etc.), which can be integrated alone or combined in various ways to form simple a simple climate model. In addition to the on-campus teaching activities, Python-based modules will be developed for use in a summer camp for local high school students.