BoBBLE: Bay of Bengal Boundary Layer Experiment

BoBBLE：孟加拉湾边界层实验

• 批准号: NE/L013827/1
• 负责人: Adrian Matthews
• 金额: $ 101.27万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FL013827%2F1
• 关键词: BoBBLE; Bay; Bengal; Boundary; Layer

The South Asian summer monsoon (June-September) provides 80% of the annual rainfall for over one billion people, many of whom depend on monsoon rains for subsistence agriculture and freshwater. It is critical to forecast accurately not only the seasonal rainfall, but also rainfall variations within the summer. Sub-seasonal "active" and "break" phases can last weeks, resulting in floods and droughts across broad areas of South Asia. Air-sea interactions are key to understanding and predicting monsoon behaviour. Ocean surface temperatures in the Bay of Bengal, east of India, remain very warm (above 28 Celsius) throughout the summer. Evaporation from the Bay provides moisture and energy to monsoon depressions that form over the Bay and bring substantial rain to India. It is not understood how the Bay remains warm despite losing energy to these systems. Ocean temperature and salinity variations across the Bay are known to drive changes in rainfall over the Bay and surrounding land, but it is not clear how these arise or how they are maintained. This is particularly true for east-west variations in the southern Bay, a focus of this project. Although air-sea interactions are important to the monsoon, weather predictions are made with models of only the atmosphere. There is potential to improve monsoon forecasts by including well-represented air-sea interactions in models. The Bay of Bengal Boundary Layer Experiment (BoBBLE) proposes an observational campaign for the southern Bay, during the established monsoon (mid-June to mid-July). BoBBLE will deploy two ships, six ocean gliders and eight floats to collect an unprecedented range of oceanic and air-sea flux observations. The ships will occupy locations in the southwest and southeast Bay, as well as tracing east-west and north-south paths between those locations, measuring ocean temperature, salinity and currents. Two gliders (automated underwater vehicles) will accompany each ship, with two others between the ships, diving to 500 metres every 2 hours to measure temperature, salinity and currents. Diurnal variations in air-sea fluxes and ocean temperatures may affect the development of weather systems. A novel configuration of the gliders will allow computations of horizontal transports of heat and salt. The floats (automated submersibles) will be deployed in the Bay to measure the ocean to 2000 metres every 5 days. They will remain in the Bay after BoBBLE, enhancing the observing network. Ships and gliders will also measure ocean chlorophyll, which absorb sunlight and alter near-surface ocean temperature, influencing air-sea interactions. BoBBLE scientists will analyse these observations, along with routine datasets, to understand the evolution of conditions in the Bay and how they influence the atmosphere. Particular emphasis will be placed on estimating the uncertainty in existing datasets of air-sea fluxes by validating them against available observations. The best-performing datasets will be used to improve estimates of air-sea exchanges and their variability on daily to decadal timescales, to calculate budgets of heat and freshwater fluxes in the Indian Ocean and the Bay, and to validate model simulations. A hierarchy of model simulations will reveal how conditions in the Bay are maintained and how air-sea interactions influence the monsoon. Simulations with an ocean model, forced by and validated against BoBBLE observations, will isolate the roles of air-sea fluxes (including the diurnal cycle), chlorophyll and horizontal transports in maintaining and recharging ocean structure after each weather system passage. Retrospective forecasts of the BoBBLE period with atmosphere-only and atmosphere-ocean coupled models will demonstrate how air-sea interactions influence monsoon rainfall predictions. Multi-decadal simulations will evaluate how air-sea interactions and coupled-model systematic errors influence daily-to-seasonal monsoon variability

南亚夏季季风（6 月至 9 月）为超过 10 亿人提供了 80% 的年降雨量，其中许多人依靠季风降雨维持生计农业和淡水。不仅准确预测季节性降雨量，而且准确预测夏季降雨量变化也至关重要。次季节的“活跃”和“中断”阶段可能持续数周，导致南亚广大地区出现洪水和干旱。海气相互作用是理解和预测季风行为的关键。印度东部孟加拉湾的海洋表面温度整个夏季都非常温暖（高于 28 摄氏度）。海湾的蒸发为海湾上空形成的季风洼地提供水分和能量，为印度带来大量降雨。目前尚不清楚尽管这些系统失去了能量，但海湾如何保持温暖。众所周知，整个海湾的海洋温度和盐度变化会导致海湾和周围土地降雨量的变化，但尚不清楚这些变化是如何产生或如何维持的。对于本项目的重点南部海湾的东西向变化尤其如此。尽管海气相互作用对季风很重要，但天气预报仅通过大气模型进行。通过在模型中纳入充分体现的海气相互作用，有可能改善季风预报。孟加拉湾边界层实验（BoBBLE）提议在季风期间（六月中旬至七月中旬）对南部海湾进行观测活动。 BoBBLE 将部署两艘船、六架海洋滑翔机和八个浮标，以收集前所未有的海洋和海空通量观测数据。这些船只将占据海湾西南和东南部的位置，并追踪这些位置之间的东西向和南北向路径，测量海洋温度、盐度和洋流。每艘船将配备两台滑翔机（自动水下航行器），另外两艘滑翔机位于船之间，每 2 小时潜入 500 米，测量温度、盐度和水流。海气通量和海洋温度的日变化可能会影响天气系统的发展。滑翔机的新颖配置将允许计算热量和盐的水平传输。这些浮标（自动潜水器）将部署在海湾，每 5 天测量一次 2000 米的海洋深度。 BoBBLE 结束后，他们将留在海湾，加强观测网络。船舶和滑翔机还将测量海洋叶绿素，它吸收阳光并改变近表面海洋温度，影响海气相互作用。 BoBBLE 科学家将分析这些观测结果以及常规数据集，以了解海湾条件的演变以及它们如何影响大气。将特别强调通过根据现有观测数据进行验证来估计现有海气通量数据集的不确定性。性能最佳的数据集将用于改进对海气交换及其每日到十年时间尺度变化的估计，计算印度洋和海湾的热量和淡水通量预算，并验证模型模拟。模型模拟的层次结构将揭示海湾条件如何维持以及海气相互作用如何影响季风。利用海洋模型进行模拟，并根据 BoBBLE 观测进行验证，将隔离海气通量（包括昼夜循环）、叶绿素和水平传输在每次天气系统经过后维持和补充海洋结构中的作用。利用仅大气模型和大气-海洋耦合模型对BoBBLE 周期进行的回顾性预测将展示海气相互作用如何影响季风降雨预测。多年代模拟将评估海气相互作用和耦合模型系统误差如何影响每日到季节的季风变化

项目成果

Spatial and temporal variability of solar penetration depths in the Bay of Bengal and its impact on sea surface temperature (SST) during the summer monsoon

夏季季风期间孟加拉湾太阳穿透深度的时空变化及其对海面温度（SST）的影响

• DOI: 10.5194/os-17-871-2021
• 发表时间: 2021
• 期刊: Ocean Science
• 影响因子: 3.2
• 作者: Giddings J

Nonlinear response of Asian summer monsoon precipitation to emission reductions in South and East Asia

• DOI: 10.1088/1748-9326/ac3b19
• 发表时间: 2022-01-01
• 期刊: ENVIRONMENTAL RESEARCH LETTERS
• 影响因子: 6.7
• 作者: Herbert, Ross;Wilcox, Laura J.;Frame, Dave
• 通讯作者: Frame, Dave

Intraseasonal Variability of Air-Sea Fluxes over the Bay of Bengal during the Southwest Monsoon

西南季风期间孟加拉湾海气通量的季节内变化

• DOI: 10.1175/jcli-d-17-0652.1
• 发表时间: 2018
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Sanchez-Franks A

Injection of Oxygenated Persian Gulf Water Into the Southern Bay of Bengal

将含氧波斯湾水注入孟加拉南部湾

• DOI: 10.1029/2020gl087773
• 发表时间: 2020
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Sheehan P

Spatial and temporal variability of solar penetration depths in the Bay of Bengal and its impact on SST during the summer monsoon

• DOI: 10.5194/os-2020-125
• 发表时间: 2021-01
• 期刊: Ocean Science Discussions
• 作者: J. Giddings;K. Heywood;A. Matthews;M. Joshi;B. Webber;A. Sanchez‐Franks;B. King;P. Vinayachandran