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Multidecadal variability of the Indonesian Throughflow (ITF) is crucial for the Indo-Pacific and global climate due to significant interbasin exchanges of heat and freshwater. Previous studies suggest that both wind and buoyancy forcing may drive ITF variability, but the role of precipitation and salinity effect in the variability of ITF on multidecadal time scales remains largely unexplored. Here, we investigate the multidecadal changes and long-term trend of the ITF transport during the past six decades, with a focus on the role of precipitation and salinity effect. The diverse datasets consistently indicate a substantial upward trend in the halosteric component of geostrophic transport of ITF in the outflow region at 114°E during the six decades. We find that the meridional differences of the salinity trend in the outflow region explain the increasing trend of the halosteric component of ITF transport. On a larger scale, the tropical western Pacific Ocean and Indonesian seas have experienced significant freshening, which has strengthened the Indo-Pacific pressure gradient and thus enhanced the ITF. In contrast, the equatorial trade wind in the western Pacific Ocean has weakened over recent decades, implying that changes in wind forcing have contributed to weakening the ITF. The combined effect of strengthened halosteric and weakened thermosteric components has resulted in a weak strengthening for the total ITF with large uncertainties. Although both the thermosteric and halosteric components are associated with natural climate modes, our results suggest that the importance of salinity effect is likely increasing given the enhanced water cycle under global warming.

 

The respective benefits and drawbacks of manual food journaling and automated dietary monitoring (ADM) suggest the value of semi-automated journaling systems combining the approaches. However, the current understanding of how people anticipate strategies for implementing semi-automated food journaling systems is limited. We therefore conduct a speculative survey study with 600 responses, examining how people anticipate approaches to automatic capture and prompting for details. Participants feel the location and detection capability of ADM sensors influences anticipated physical, social, and privacy burdens. People more positively anticipate prompts which contain information relevant to their journaling goals, help them recall what they ate, and are quick to respond to. Our work suggests a tradeoff between ADM systems' detection performance and anticipated acceptability, with sensors on facial areas having higher performance but lower acceptability than sensors in other areas and more usable prompting methods like those containing specific foods being more challenging to produce than manual reminders. We suggest opportunities to improve higher-acceptability, lower-accuracy ADM sensors, select approaches based on individual and practitioner journaling needs, and better describe capabilities to potential users. 

Studies of personal informatics systems primarily examine people's use or non-use, but people often leverage other technology towards their long-term behavior change processes such as social platforms. We explore how tracking technologies and social platforms together help people build healthy eating behaviors by interviewing 18 people who use Chinese food journaling apps. We contribute a Model of Socially Sustained Self-Tracking in personal informatics, building on the past model of Personal Informatics and the learning components of Social Cognitive Theory. The model illustrates how people get advice from social platforms on when and how to track, transfer data to and apply knowledge from social platforms, evolve to use social platforms after tracking, and occasionally resume using tracking tools. Observational learning and enactive learning are central to these processes, with social technologies helping people to gain deeper and more reliable domain knowledge. We discuss how lapsing and abandoning of tracking can be viewed as evolving to social platforms, offering recommendations for how technology can better facilitate this evolution. 

Various contact tracing approaches have been applied to help contain the spread of COVID-19, with technology-based tracing and human tracing among the most widely adopted. However, governments and communities worldwide vary in their adoption of digital contact tracing, with many instead choosing the human approach. We investigate how people perceive the respective benefits and risks of human and digital contact tracing through a mixed-methods survey with 291 respondents from the United States. Participants perceived digital contact tracing as more beneficial for protecting privacy, providing convenience, and ensuring data accuracy, and felt that human contact tracing could help provide security, emotional reassurance, advice, and accessibility. We explore the role of self-tracking technologies in public health crisis situations, highlighting how designs must adapt to promote societal benefit rather than just self-understanding. We discuss how future digital contact tracing can better balance the benefits of human tracers and technology amidst the complex contact tracing process and context. 

The moderate DI¹³C isotope enrichment (MoDIE) method by Powers et al. (2017) is a promising method to precisely measure the photochemical mineralization of dissolved organic carbon (DOC) in water samples without dramatically altering a sample's pH or organic carbon pool. Here, we evaluated the analytical uncertainties of the MoDIE method and used Monte Carlo simulations to optimize the experimental design for the most precise measurements of dissolved inorganic carbon (DIC) that is produced photochemically (DIC_hν). Analytically, we recommend calculating yields of DIC_hvwith an exact expression of conservation of mass that intrinsically reduces error and uncertainty. Methodologically, the overall uncertainty and detection limit of the MoDIE method can be significantly reduced by partially stripping away the original DIC pool, enriching the residual DIC with more DI¹³C, and increasing the yields of DIC_hvvia longer irradiation. Instrumentally, more precise measurements of enriched δ¹³C values before and after irradiation are needed to further improve the precision of DIC_hνconcentration determinations. Higher precision DIC_hvmeasurements via the optimized MoDIE method can improve our understanding of the photochemical mineralization of DOC and thus the budget of marine DOC. The optimizations and detection limits reported here will become more refined as measurements and associated uncertainties from future MoDIE experiments become available.

 

Foreshock transients can result in significant dynamic pressure perturbations downstream, causing the magnetopause to move locally outward and inward. These near‐magnetopause phenomena in turn generate magnetospheric field‐aligned currents (FACs). FACs driven by solar wind impulses are commonly found to be due to flow vortices, but it remains unclear whether the FACs driven by those localized foreshock transients are contributed by flow vortices or pressure gradients. We report on a fortuitous conjunction between the Magnetospheric Multiscale (MMS) mission, which was observing a foreshock transient at the flank of the bow shock, and the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, immediately downstream of MMS, which was observing magnetopause disturbances arising from that transient. Using observations from the three THEMIS spacecraft to calculate local current density perturbations within the outward motion region of the magnetosphere, we find that flow vortices play a dominant role in generating the current there; the contribution from pressure gradients is one order of magnitude smaller. Using a global hybrid simulation that reproduces the observed foreshock transient perturbations, we traced the simulated FACs generated by the transient's interaction with the magnetopause. We find that in the outward magnetopause motion region the simulated FACs are driven by flow vortices, in agreement with THEMIS observations. Deeper inside the magnetosphere, the faster convection of bipolar flow vortices than the local magnetospheric flow leads to reversal of the simulated FACs. Our results improve our understanding of how foreshock transients disturb and energize the magnetosphere‐ionosphere system.

 

The research community on the study and design of systems for personal informatics has grown over the past decade. To take stock of what the topics the field has studied and methods the field has used, we map and label 523 publications from ACM's library, IEEE Xplore, and PubMed. We surface that the literature has focused on studying and designing for health and wellness domains, an emphasis on understanding and overcoming barriers to data collection and reflection, and progressively fewer contributions involving artifacts being made. Our mapping review suggests directions future research could explore, such as identifying and resolving barriers to tracking stages beyond collection and reflection, engaging more with domain experts, and further discussing the privacy and ethical concerns around tracked data.