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Although the global greening associated with climate change is well documented on land, similar trends in the ocean have not been thoroughly identified. Using satellite observations of ocean chlorophyll a (Chl) concentration, we show that the surface ocean experienced a poleward greening from 2003 to 2022. Contemporaneously, the subtropical regions of the Northern Hemisphere experienced a decrease in Chl. As such, the latitudinal disparity in Chl, as documented by an inequality index, has been increasing over the past two decades, particularly in the Northern Hemisphere. Rising water temperatures may primarily influence the Chl trends. The increasing Chl inequality—marked by “greener green and bluer blue” waters—has the potential to cascade to higher trophic levels, with implications for the fisheries and economies of coastal nations. 

Abstract—Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a powerful technique for elemental compositional analysis and depth profiling of materials. However, it encounters the problem of matrix effects that hinder its application. In this work, we introduce a pioneering ToF-SIMS calibration method tailored for SixGeySnz ternary alloys. SixGe1-x and Ge1-zSnz binary alloys with known compositions are used as calibration reference samples. Through a systematic SIMS quantification study of SiGe and GeSn binary alloys, we unveil a linear correlation between secondary ion intensity ratio and composition ratio for both SiGe and GeSn binary alloys, effectively mitigating the matrix effects. Extracted relative sensitivity factor (RSF) value from SixGe1-x (0.07<0.83) and Ge1-zSnz (0.066<0.183) binary alloys are subsequently applied to those of SixGeySnz (0.011<0.113, 0.863<0.935 and 0.023<0.103) ternary alloys for elemental compositions quantification. These values are cross-checked by Atom Probe Tomography (APT) analysis, an indication of the great accuracy and reliability of as-developed ToF-SIMS calibration process. The proposed method and its reference sample selection strategy in this work provide a low-cost as well as simple-to-follow calibration route for SiGeSn composition analysis, thus driving the development of next-generation multifunctional SiGeSn-related semiconductor devices.