Mixing in the Equatorial Atlantic's Cold Tongue- Chipods on PIRATA Moorings

东赤道太平洋和大西洋以相对较冷的表层水为标志，被称为太平洋和赤道冷舌。虽然大西洋冷舌比太平洋冷舌小，但它的幅员辽阔，横跨赤道，横跨几度纬度，横跨数十度经度。这些冷舌起到了大气热量汇的作用，对全球热量平衡至关重要。赤道地区海表面温度的季节变化周期由东向西依次递减。降温峰值出现在北方夏季，首先在东部，然后向西推进。大西洋冰冷的舌头对大洋两岸产生了相当大的区域影响，导致巴西东北部的降雨量不同，并影响了西非人口稠密地区的天气模式。然而，目前还不存在可与太平洋冷舌进行比较的大西洋冷舌的测量结果。该项目将缩小这一差距，并查明太平洋和大西洋盆地赤道混合制度之间的主要差异。一名博士后助理将参与对新观测结果的广泛分析，并接受赤道动力学方面的培训。工科本科生将在暑期受雇，帮助建造和测试仪器。将继续支持Mary‘s Peak网络摄像头。这是安装在俄勒冈州立大学海洋学大楼屋顶上的网络摄像头，它提供了云层追踪的自然流体流动的可视化，提供了对大气中流体运动的教育一瞥。该项目还将补充正在进行的太平洋冷舌测量、热带不稳定波的理论分析以及正在进行的热带大西洋国际研究。数据集将被存档并与社区共享。在赤道以外，海表面温度(SST)的年度循环与季节变化的太阳加热有关。尽管赤道海洋常年受到大气的加热，但它们在海温中也表现出年度循环。最近对太平洋和大西洋赤道冷语的不同测量证实，混合在北部夏季海面冷却中起主导作用，从而产生SST的这一年度循环。这两种冷淡的语言之间至少存在着两个重大而令人费解的差异。首先，来自大西洋的测量表明，大西洋不存在对赤道上太平洋混合至关重要的深层日混合循环(混合层以下但赤道潜流核心以上)。其次，气候模型预测太平洋的冰冷舌头太冷，大西洋的冰冷舌头太热。现已建立的Pirata(热带大西洋中的试点研究系泊阵列)阵列正在为赤道大西洋动力学及其在大洋两岸关键天气模式中的作用提供新的见解。该项目将以它为支柱，测量大西洋冷舌混合的垂直结构和短期变化，以便与从太平洋冷舌中了解到的情况进行比较。五个新开发的混合器(X-Pod)将分别部署在横跨大西洋冷舌的两个赤道Pirata系泊设备上，功率分别为10W和23W，为期四年。这两个系泊地拥有密集的上层海洋采样、表层气象和洋流的垂直剖面，以补充混合测量。这些新的观测将确定冷舌混合的季节和年际变化，以及它如何影响SST和观测到的大西洋冷舌的减弱，并确定太平洋和大西洋混合的差异产生SST趋势中两极气候模式响应的机制。

The eastern equatorial Pacific and Atlantic Oceans are marked by relatively cool surface water, referred to as the Pacific and Equatorial cold tongues. Although smaller than the Pacific cold tongue, the Atlantic cold tongue is expansive, spanning several degrees latitude across the Equator and tens of degrees longitude. These cold tongues act as sinks for atmospheric heat and are critical to the global heat balance. The seasonal cycle in sea surface temperature varies in magnitude decreasing from east to west along the equator. Peak cooling occurs in boreal summer, first in the east and progressing westward. The Atlantic's cold tongue exerts considerable regional influence on both sides of the ocean, contributing to variable rainfall over Northeast Brazil and to weather patterns in densely populated areas of western Africa. However, measurements in the Atlantic cold tongue comparable to those made in the Pacific cold tongue do not presently exist. This project will close this gap and discern primary differences between the equatorial mixing regimes in the Pacific and Atlantic basins. A post-doctoral associate will participate in a broad analysis of the new observations and be trained in equatorial dynamics. Undergraduate engineering students will be employed in summer months to help with construction and testing of instrumentation. The Mary's Peak webcam will continue to be supported. This is a webcam installed on the roof of the Oceanography building at the Oregon State University that provides a visualization of natural fluid flows traced by clouds, providing an educational glimpse into fluid motions in the atmosphere. This project will also complement ongoing measurements in the Pacific cold tongue, theoretical analyses of Tropical Instability Waves, and ongoing international studies in the tropical Atlantic. The data set will be archived and shared with the community.Away from the equator, the annual cycle in sea surface temperature (SST) is related to seasonally-varying solar heating. Despite the fact that the equatorial oceans are heated year round by the atmosphere, they also exhibit an annual cycle in SST. Recent, yet distinct, measurements in the equatorial cold tongues of both Pacific and Atlantic Oceans establish the dominant role that mixing plays in boreal summer cooling of the sea surface to produce this annual cycle in SST. At least two significant, and puzzling, differences exist between the two cold tongues. Firstly, measurements from the Atlantic show that the deep diurnal mixing cycle (below the mixed layer but above the core of the Equatorial Undercurrent), which is so critical to mixing in the upper equatorial Pacific, is not present in the Atlantic. Secondly, climate models predict a Pacific cold tongue that is too cool and an Atlantic cold tongue that is too warm. The now well-established PIRATA (Pilot Research Moored Array in the Tropical Atlantic) array is providing new insight into equatorial Atlantic dynamics and its role in critical weather patterns on both sides of that ocean. This project will use it as the backbone to measure the vertical structure and short-time variability of cold tongue mixing in the Atlantic, for comparison to what has been learned from the Pacific cold tongue. Five newly-developed mixing meters (chi-pods) will each be deployed on two equatorial PIRATA moorings at 10W and 23W across the Atlantic cold tongue for a period of four years. These two moorings have dense upper ocean sampling, surface meteorology, and vertical profiles of ocean currents to complement the mixing measurements. These new observations will establish seasonal and inter-annual variations of cold tongue mixing and how it influences SST and the observed weakening of the Atlantic cold tongue, and also define the mechanisms for differences in Pacific and Atlantic mixing that creates the bipolar climate model responses in SST trends.