Comparing the Ocean Color Measurements Between MOS and SeaWiFS: A Vicarious Intercalibration Approach for MOS

One of the primary goals of the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) project is to develop methods for meaningful comparison and possible merging of data products from multiple ocean color missions. The Modular Optoelectronic Scanner (MOS) is a German instrument that was launched in the spring of 1996 on the Indian IRS-P3 satellite. With the successful launch of NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) in the summer of 1997, there are now two ocean color missions in concurrent operation and there is interest within the scientific community to compare data from these two sensors. In this paper, we describe our efforts to retrieve ocean optical properties from both SeaWiFS and MOS using consistent methods. We first briefly review the atmospheric correction, which removes more than 90% of the observed radiances in the visible, and then describe how the atmospheric correction algorithm used for the SeaWiFS data can be modified for application to other ocean color sensors. Next, since the retrieved water-leaving radiances in the visible between MOS and SeaWiFS are significantly different, we developed a vicarious intercalibration method to recalibrate the MOS spectral bands based on the optical properties of the ocean and atmosphere derived from the coincident SeaWiFS measurements. We present and discuss the MOS retrieved ocean optical properties before and after the vicarious calibration, and demonstrate the efficacy of this approach. We show that it is possible and efficient to vicariously intercalibrate sensors between one and another

Magnetic skyrmion generation by reflective spin-wave focusing

We propose a method to generate magnetic skyrmions by focusing spin waves totally reflected by a curved film edge. Based on the principle of identical magnonic path length, we derive the edge contour that is parabolic and frequency-independent. Micromagnetic simulations are performed to verify our theoretical design. It is found that under proper conditions, magnetic droplet first emerges near the focal point where the spin-wave intensity has been significantly enhanced, and then converts to magnetic skyrmion accompanied by a change of the topological charge. The phase diagram about the amplitude and frequency of the driving field for skyrmion generation is obtained. Our finding would be helpful for the designment of spintronic devices combing the advantage of skyrmionics and magnonics.Comment: 5 pages, 5 figure

Association between marijuana use and kidney stone: a cross-sectional study of NHANES 2009 to 2018

Objective: The purpose of this investigation is to determine whether regular marijuana use is related to history of kidney stones in the US population.Methods: Data were obtained from the National Health and Nutrition Examination Survey (NHANES) from 2009 to 2018. Kidney stone and marijuana use data were collected from self-report questionnaires. Multivariate logistic regression and multiple sensitivity analyses were applied to examine the relationship between marijuana usage and kidney stones.Results: There are approximately 26.04% of the US population have admitted to using marijuana in their lifetime. Compared with none regular users, those with a higher frequency of marijuana use were more males, more non-Hispanic races, lower than high school education, overweight, no recreational activity, without diabetes mellitus, and more coronary heart disease. After adjusting for potential confounders, multivariate regression analysis demonstrated that marijuana use was inversely correlated to kidney stones in males (Odds ratio [OR] = 0.72, 95% Confidence interval [CI] = 0.54–0.97). One to seven times/week regular consumption of marijuana was associated with kidney stones in males (OR = 0.62, 95% CI = 0.43–0.89). Sensitivity analyses validated the robustness of our outcomes.Conclusion: Our findings revealed that regular marijuana male users were inversely associated with kidney stones. Marijuana use one to six times/week was inversely related to the risk of kidney stones in males. Further studies are required to explore the dose and type associations of marijuana with kidney stones

The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2

On 13 December 2012, Chang'e-2 conducted a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 $\pm$ 120 meters from the asteroid's surface. The highest-resolution image, with a resolution of better than 3 meters, reveals new discoveries on the asteroid, e.g., a giant basin at the big end, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, which suggests that Toutatis may bear a rubble-pile structure. Toutatis' maximum physical length and width are (4.75 $\times$ 1.95 km) $\pm$10$\%$, respectively, and the direction of the +$z$ axis is estimated to be (250$\pm$5$^\circ$, 63$\pm$5$^\circ$) with respect to the J2000 ecliptic coordinate system. The bifurcated configuration is indicative of a contact binary origin for Toutatis, which is composed of two lobes (head and body). Chang'e-2 observations have significantly improved our understanding of the characteristics, formation, and evolution of asteroids in general.Comment: 21 pages, 3 figures, 1 tabl

An empirical algorithm to seamlessly retrieve the concentration of suspended particulate matter from water color across ocean to turbid river mouths

Abstract(#br)We propose a globally applicable algorithm (GAA SPM ) to seamlessly retrieve the concentration of suspended particulate matter (SPM) ( C SPM ) from remote sensing reflectance ( R rs ( λ )) across ocean to turbid river mouths without any hard-switching in its application. GAA SPM is based on a calibrated relationship between C SPM and a generalized index for SPM ( GI SPM ) from water color. The GI SPM is mainly composed of three R rs ( λ ) ratios (671, 745, and 862 nm over 551 nm, respectively), along with weighting factors assigned to each ratio. The weighting factors are introduced to ensure the progressive application of R rs ( λ ) in the longer wavelengths for increasing C SPM . Calibration of GAA SPM employed data collected from multiple estuarine and coastal regions of Europe, China, Argentina, and the USA with the measured C SPM spanning from 0.2 to 2068.8 mg/L. Inter-comparison with several recalibrated well-known C SPM retrieval algorithms demonstrates that GAA SPM has the best retrieval accuracy over the entire C SPM range with a relative mean absolute difference (rMAD) of 41.3% (N = 437). This averaged uncertainty in GAA SPM -derived C SPM is mostly attributed to the retrievals from less turbid waters where C SPM < 50 mg/L (rMAD = 50%, N = 214). GAA SPM was further applied to the Visible Infrared Imaging Radiometer Suite (VIIRS) measurements over prominent coastal areas and produced reliable C SPM maps along with realistic spatial patterns. In contrast, applications of other C SPM algorithms resulted in less reliable C SPM maps with either unjustified numerical discontinuities in the C SPM spatial distribution or unsatisfactory retrieval accuracy. Therefore, we propose GAA SPM as a preferred algorithm to retrieve C SPM over regions with a wide range of C SPM , such as river plume areas

Trichodesmium around Australia: A view from space

Responsible for half of the ocean's nitrogen input through nitrogen fixation, the saltwater cyanobacterium Trichodesmium is ubiquitous in global tropical and subtropical oceans but particularly abundant around Australia. However, although the earliest report goes back to the 18th century, the knowledge of where and when large quantities of Trichodesmium can be found around Australia is still incomplete. Based on satellite imagery and deep learning, we quantified relative abundance of Trichodesmium around Australia for the period of 2012–2021. Surface aggregations of Trichodesmium were found almost everywhere except the southern coast, with a cumulative footprint exceeding 4.6 million km2. Strong seasonality was found, with peak months between September and November. The spatial distributions and seasonality were found to correlate well with water temperature, iron-rich dust from Australian desert, and black carbon aerosols from frequent bushfires. With the projected ocean warming in the coming century, Trichodesmium may expand further south, making the cumulative footprint even larger

Sensor capability and atmospheric correction in ocean colour remote sensing

© 2015 by the authors; licensee MDPI, Basel, Switzerland. Accurate correction of the corrupting effects of the atmosphere and the water's surface are essential in order to obtain the optical, biological and biogeochemical properties of the water from satellite-based multi-and hyper-spectral sensors. The major challenges now for atmospheric correction are the conditions of turbid coastal and inland waters and areas in which there are strongly-absorbing aerosols. Here, we outline how these issues can be addressed, with a focus on the potential of new sensor technologies and the opportunities for the development of novel algorithms and aerosol models. We review hardware developments, which will provide qualitative and quantitative increases in spectral, spatial, radiometric and temporal data of the Earth, as well as measurements from other sources, such as the Aerosol Robotic Network for Ocean Color (AERONET-OC) stations, bio-optical sensors on Argo (Bio-Argo) floats and polarimeters. We provide an overview of the state of the art in atmospheric correction algorithms, highlight recent advances and discuss the possible potential for hyperspectral data to address the current challenges