Collaborative Research: RAPID: Pilot observations of enhanced near-bottom equatorial turbulence

低纬度的深太平洋被认为是翻转环流的一个关键的深海上升流分支的所在地。这种上升流需要从密度较低的上层海洋向下混合浮力。然而，驱动这一过程的深层机制目前知之甚少，而且相对较少采样。该项目将利用140°W的资助系泊阵列（美国国家科学基金会项目OCE-2048660“评估热带不稳定波下增强混合机制”的一部分），对深海混合进行首次全年高分辨率赤道观测。资助的系泊计划于2023年底部署。计划在0.5°N和3°N的系泊处增加仪器，使用点和剖面电流计以及密集定位的温度传感器来观察底部边界层。这个试点项目将有助于了解全球环流的低纬度扩散上升流分支，这是气候的一个基本组成部分。这些观测结果将用于测试几种假设的深海赤道湍流机制，包括：由地球自转的水平分量驱动的近底波捕获，地形背风波驱动的混合，以及由波驱动的流体远离赤道的位移产生的惯性不稳定性。该项目将促进对赤道深部动力学和翻转环流的认识，为未来观测赤道太平洋深部混合提供信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The low-latitude deep Pacific is known to be the locus of a critical abyssal upwelling branch of the overturning circulation. This upwelling requires diapycnal mixing of buoyancy downward from the less dense upper ocean. However, the diapycnal mechanisms driving this process are currently poorly understood and relatively poorly sampled. This project will leverage a funded mooring array at 140°W (part of the NSF project OCE-2048660 “Evaluating mechanisms for enhanced mixing below tropical instability waves”) to make the first full year, high-resolution equatorial observations of abyssal mixing. The funded moorings are scheduled to be deployed at the end of 2023. Instrumentation will be added to the mooring planned for 0.5 and 3°N latitutde to observe the bottom boundary layer, using point and profiling current meters and a dense positioning of temperature sensors.This pilot project will inform understanding of the low-latitude diffusive upwelling branch of the global circulation, a fundamental component of climate. The observations will be used to test several hypothesized abyssal equatorial turbulence mechanisms including: near-bottom wave trapping driven by the horizontal component of the Earth's rotation, topographic lee-wave- driven mixing, and inertial instability generated through wave-driven displacement of fluid away from the equator. The project will advance knowledge of deep equatorial dynamics and the overturning circulation to inform future observations of mixing in the deep equatorial Pacific.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.