An Analysis of SSH Ridges and SST Frontal Bands in Mid-Latitude Oceans

知识价值：月平均海温锋面概率图像显示了所有主要海洋盆地中纬度的纬向带，经向间隔约为400 km。这些带在视觉上与南太平洋东部海面高度异常脊线和水深测量相关。此外，它们在许多年内都是稳定的。产生这些特征的动力目前还不清楚。目前的假设范围从斜压不稳定和地转湍流引起的纬向喷流到由平均流或涡旋相互作用决定的首选涡旋路径。该项目的具体目标是：量化平均海面场锋面概率持续带与持续脊的关系；确定海温锋面概率准纬向带的来源和维持；探讨锋面概率场中波段位置的年际变化特征；分析了底部地形对锋面概率带的影响。观测到的纬向结构的普遍性、纬向范围、时间上的持久性以及在所有盆地和所有季节中一致的经向尺度表明，它们是海洋基本动力过程的结果。这些构造的特征与深海测深之间的紧密对应表明，它们与延伸到主温跃层以下的过程有关。因此，了解它们的起源可能有助于更好地了解海洋的总体环流。更广泛的影响：在项目过程中，将向海洋学界提供从1981年至今的各种卫星海温场的各种空间和时间分辨率的锋面数据集。初步研究表明，海温异常对大气的影响与锋面带有关。具体来说，这些异常上空的大气水汽比背景高。还有一种潜在的与地质学的联系，因为与这些带相关的特征在时间上是持续的——可能在很长一段时间内对海底的沉积和冲刷产生影响。了解纬向条纹的动力学和持久性对于理解影响气候的长时间尺度的海洋运输也很重要，从而有助于我们理解海洋在地球气候中的作用。这也将促使人们努力将这些海洋过程参数化，以便在粗耦合全球气候模式中表示。本建议所发展的波段探测算法及其分析提供了重要的尺度信息，可用于全球海洋观测系统的设计和维护。该项目还将支持一名研究生的培训。

Intellectual Merit: Images of monthly averaged sea surface temperature (SST) front probability show zonal bands at mid-latitudes in all major ocean basins with a meridional separation of approximately 400 km. These bands are visually correlated with ridges of sea surface height (SSH) anomaly in the eastern South Pacific and with bathymetry. Furthermore, they are stable over many years. The dynamics giving rise to these features are not understood at present. Current hypotheses range from zonal jets resulting from baroclinic instability and geostrophic turbulence to preferred eddy pathways determined by mean flows or eddy interactions. The specific objectives of this project are: to quantify the relationship between persistent bands of frontal probability and persistent ridges in mean SSH fields; to determine the origin and maintenance of quasi-zonal bands of SST front probability; to characterize the inter-annual variability of the location of bands in the frontal probability fields; and, to analyze the impact of bottom topography on bands of frontal probability. The ubiquity of the observed zonal structures, their zonal extent, their persistence in time and the uniform meridional scale in all basins and all seasons suggests that they result from fundamental dynamic processes in the ocean. The tight correspondence between features in these structures and deep bathymetry suggests that they are involved with processes that extend well below the main thermocline. As such, understanding their origin will likely contribute to a better understanding of the general circulation of the ocean. Broader Impacts: In the course of the project, frontal data sets from a variety of satellite-derived SST fields extending from 1981 to present at a variety of spatial and temporal resolutions will be made available to the oceanographic community. Preliminary work suggests an ocean to atmosphere impact of the SST anomalies associated with frontal bands. Specifically, atmospheric water vapor is higher over these anomalies than the background. There is also a potential connection with geology in that the features associated with the bands are persistent in time - possibly over very long times with impacts on deposition on and scouring of the sea floor. Understanding the dynamics and persistence of the zonal striations will also be important to understanding ocean transports over long timescales affecting climate and thereby benefit our understanding of the ocean role in Earth's climate. This would also motivate efforts for parameterizing these ocean processes for representation in coarse coupled global climate models. The band detection algorithms and the analyses therein, as developed in this proposal, provide important scale information that can be useful in the design and maintenance of global ocean observing systems. This project will also support the training of one graduate student.