The role of mesoscale eddies in transporting Agulhas leakage is investigated using a recent technique from nonlinear dynamical systems theory applied on geostrophic currents inferred from the over two-decade-long satellite altimetry record. Eddies are found to acquire material coherence away from the Agulhas retroflection, near the Walvis Ridge in the South Atlantic. Yearly, 1 to 4 coherent material eddies are detected with diameters ranging from 40 to 280 km. A total of 23 eddy cores of about 50 km in diameter and with at least 30\pct of their contents traceable into the Indian Ocean were found to travel across the subtropical gyre with minor filamentation. Only 1 eddy core was found to pour its contents on the North Brazil Current. While ability of eddies to carry Agulhas leakage northwestward across the South Atlantic is supported by our analysis, this is more restricted than suggested by earlier ring transport assessments.
Artificial light at night is a relevant environmental stressor whose unwanted consequences have been documented by a growing body of research. In this work we analize the loss of the natural darkness of the night in aquaculture farms located in shallow waters close to the shoreline, in the Atlantic coast of Galicia. High-luminance LED lampposts are switched-on the whole night long for surveillance purposes, significantly increasing the light levels throughout the whole water column, from the surface to the seabed. Measured in terms of the weighted radiance associated with the significant magni…
Dissipating the correlation smokescreen: Causal decomposition of the radiative effects of biomass burning aerosols over the South-East Atlantic
ETH Zurich（苏黎世联邦理工学院）；University of Colorado, Boulder（科罗拉多大学博尔德分校）；NOAA（美国国家海洋和大气管理局）；Colorado State University（科罗拉多州立大学）；University of Lausanne（洛桑大学）；GeoSphere Austria（奥地利地球科学研究所）
In situ boundary arrays have been installed in the North Atlantic to measure the large-scale ocean circulation. Here, we use measurements at the western edge of the North Atlantic at $16^\circ$N and $26^\circ$N to investigate low-frequency variations in deep densities and their associated influence on ocean transports. At both latitudes, deep waters (below 1100 dbar) at the western boundary are becoming fresher and less dense. The associated change in geopotential thickness is about $0.15$ $\mbox{m}^2\mbox{s}^{-2}$ between 2004-2009 and 2010-2014, with the shift occurring between 2009-2010 and…
We use Transition Path Theory (TPT) to frame, in a statistically more robust fashion than earlier analyses, equatorward routes of North Atlantic Deep Water (NADW) in the subpolar North Atlantic. TPT is applied on all available RAFOS and Argo floats in the area by means of a discretization of the Lagrangian dynamics described by their trajectories. By considering floats at different depths, we investigate transition paths of NADW in its upper (UNADW) and lower (LNADW) layers. We find that the majority of UNADW transition paths sourced in the Labrador and southwestern Irminger Seas reach the wes…
A Regime Shift in Atlantic Surface Currents Reveals a Step-like Decline of the Meridional Overturning Circulation
Beijing Normal University（北京师范大学）；Zhejiang University（浙江大学）；Kunming University of Science and Technology（昆明理工大学）；Technical University of Munich（慕尼黑工业大学）；Potsdam Institute for Climate Impact Research（波茨坦气候影响研究所）；Tsinghua University（清华大学）；Peking University（北京大学）
During the last ice age several quasi-periodic abrupt warming events took place. Known as Dansgaard-Oeschger (DO) events their effects were felt globally, although the North Atlantic experienced the largest temperature anomalies. Paleoclimate data shows that the fluctuations often occurred right after massive glacial meltwater releases in the North Atlantic and in bursts of three or four with progressively decreasing strengths. In this study a simple dynamical model of an overturning circulation and sea ice is developed with the goal of understanding the fundamental mechanisms that could have …
We show that filamentous Atmospheric Rivers (ARs) over the Northern Atlantic Ocean are closely linked to attracting Lagrangian Coherent Structures (LCSs) in the large scale wind field. LCSs represent lines of attraction in the evolving flow with a significant impact on all passive tracers. Using Finite-Time Lyapunov Exponents (FTLE), we extract LCSs from a two-dimensional flow derived from water vapor flux of atmospheric reanalysis data and compare them to the three-dimensional LCS obtained from the wind flow. We correlate the typical filamentous water vapor patterns of ARs with LCSs and find …
Formation and evolution of turbulence in convectively unstable internal solitary waves of depression shoaling over gentle slopes in the South China Sea
Cornell University（康奈尔大学）；University of Washington（华盛顿大学）；University of Waterloo（滑铁卢大学）；Wandering Wakhs Research（Wandering Wakhs 研究）
Deep Learning Models for Flood Predictions in South Florida
Florida International University（佛罗里达国际大学）；Knight Foundation School of Computing and Information Sciences, Florida International University（佛罗里达国际大学奈特基金会计算与信息科学学院）；Department of Civil and Environmental Engineering, Florida International University（佛罗里达国际大学土木与环境工程系）；Sea Level Solutions Center, Florida International University（佛罗里达国际大学海平面解决方案中心）
The Southern Ocean plays an integral role in the global climate system, exchanging heat, salt, and carbon throughout the major ocean basins via the deep, fast-flowing Antarctic Circumpolar Current. The Antarctic Circumpolar Current is bounded by spatially and temporally varying fronts that partition distinct water masses. Locating and quantifying cross-front transport is crucial for understanding global patterns of inter-basin exchange; however, this is challenging because fronts are typically defined by hydrographic properties, such as temperature or salinity, which are subject to external so…
Simulations with the Max Planck Institute Martian general circulation model for Martian years 28 and 34 reveal details of the water "pump" mechanism and the role of gravity wave (GW) forcing. Water is advected to the upper atmosphere mainly by upward branches of the meridional circulation: in low latitudes during equinoxes and over the south pole during solstices. Molecular diffusion plays little role in water transport in the middle atmosphere and across the mesopause. GWs modulate the circulation and temperature during global dust storms, thus changing the timing and intensity of the transpo…
