Fieldwork, including work done at sea, is a key component of many geoscientists' careers. Recent studies have highlighted the pervasive sexual harassment faced by women during fieldwork. However, transgender and gender diverse scientists face unique obstacles, which have not yet been studied. We partially fill this gap by sharing our experiences as transgender and gender diverse people. We have experienced sexual harassment, misconduct, privacy issues, and legal and medical struggles as we conduct seagoing work. We provide recommendations to make seagoing work safer to our communities. These recommendations are a starting point to make seagoing work more inclusive for all.

Fronts are ubiquitous in the climate system. In the Southern Ocean, fronts delineate water masses, which correspond to upwelling and downwelling branches of the overturning circulation. A robust understanding of Southern Ocean fronts is key to projecting future changes in overturning and the associated air-sea partitioning of heat and carbon. Classically, oceanographers define Southern Ocean fronts as a small number of continuous linear features that encircle Antarctica. However, modern observational and theoretical developments are challenging this traditional framework to accommodate more localized views of fronts [Chapman et al. 2020]. In this work, we present two related methods for calculating fronts from oceanographic data. The first method uses unsupervised classification (specifically, Gaussian Mixture Modeling or GMM) and an interclass metric to define fronts. This approach produces a discontinuous, probabilistic view of front location, emphasising the fact that the boundaries between water masses are not uniformly sharp across the entire Southern Ocean. The second method uses Sobel edge detection to highlight rapid changes [Hjelmervik & Hjelmervik, 2019]. This approach produces a more local view of fronts, with the advantage that it can highlight the movement of individual eddy-like features (such as the Agulhas rings). The fronts detected using the Sobel method are moderately correlated with the magnitude of the velocity field, which is consistent with the theoretically expected spatial coincidence of fronts and jets. We will present our python GitHub repository, which will allow researchers to easily apply these methods to their own datasets. Figure caption Two methods for interpretable front detection. Solid lines represent classical fronts. (a) The “inter-class” metric, which indicates the probability that a grid cell is a boundary between two classes. The classes are defined by GMM of principal component values (PCs) derived from both temperature and salinity. The different colors indicate different class boundaries. (b) Sobel edge detection: approximately the magnitude of the spatial gradient of the PCs divided by each field’s standard deviation, which highlights locations of rapid change.

The causes of decadal variations in global warming are poorly understood, however it is widely understood that variations in ocean heat content are linked with variations in surface warming. To investigate the forced response of ocean heat content (OHC) to anthropogenic aerosols (AA), we use an ensemble of historical simulations, which were carried out using a range of anthropogenic aerosol forcing magnitudes in a CMIP6-era global circulation model. We find that the centennial scale linear trends in historical ocean heat content are significantly sensitive to AA forcing magnitude ($-3.0\pm0.1$ x10$^{5}$ (J m$^{-3}$ century$^{-1}$)/(W m$^{-2}$), R$^2$=0.99), but interannual to multi-decadal variability in global ocean heat content appear largely independent of AA forcing magnitude. Comparison with observations find consistencies in different depth ranges and at different time scales with all but the strongest aerosol forcing magnitude, at least partly due to limited observational accuracy. We find broad negative sensitivity of ocean heat content to increased aerosol forcing magnitude across much of the tropics and sub-tropics. The polar regions and North Atlantic show the strongest heat content trends, and also show the strongest dependence on aerosol forcing magnitude. However, the ocean heat content response to increasing aerosol forcing magnitude in the North Atlantic and Southern Ocean is either dominated by internal variability, or strongly state dependent, showing different behaviour in different time periods. Our results suggest the response to aerosols in these regions is a complex combination of influences from ocean transport, atmospheric forcings, and sea ice responses.

{Dotson Ice Shelf (DIS) in West Antarctica is undergoing rapid basal melting driven by intrusions of warm, saline Circumpolar Deep Water (CDW) onto the continental shelf. Meltwater from DIS is thought to influence biology in the adjacent Amundsen Sea Polynya (ASP), which exhibits the highest Net Primary Productivity (NPP) per unit area of any coastal polynya in the Southern Ocean. However, the relative importance of iron and light in colimiting the spring phytoplankton bloom in the ASP remains poorly understood. In this modelling study we first investigate the mechanisms by which ice shelves impact NPP, then map spatio-temporal patterns in iron-light colimitation, and finally examine the environmental drivers of iron and light supply. We find that ice shelf melting leads to greater upper ocean iron concentrations, both directly due to release of iron from sediments entrained at the glacier bed, and indirectly via a buoyancy driven overturning circulation which pulls iron from CDW to the surface. Both of these mechanisms increase NPP compared to experiments where ice shelf melt is suppressed. We then show that the phytoplankton self-shading feedback delays the bloom and reduces peak NPP by 80\% compared to experiments where light penetration is independent of chlorophyll. Iron limitation due to phytoplankton uptake is more important a) later in the season, b) higher in the water column and c) further from the ice shelf; as compared to light limitation. Finally, sensitivity experiments show that variability in CDW intrusion influences NPP by controlling the horizontal spreading of iron-rich meltwater.}

The Weddell Gyre is a dominant feature of the Southern Ocean and an important component of the climate system; it regulates air-sea exchanges, controls the formation of deep and bottom water, and hosts upwelling of relatively warm subsurface waters. It is characterized by extremely low sea surface temperatures, active sea ice formation, and widespread salt stratification that stabilizes the water column. Studying the Weddell Gyre is difficult, as it is extremely remote and largely covered with sea ice; at present, it is one of the most poorly-sampled regions of the global ocean, highlighting the need to extract as much value as possible from existing observations. Thanks to recent efforts of the EU SO-CHIC project, much of the existing Weddell Gyre data, including ship-based CTD, seal tag, and Argo float profiles, has been assembled into a coherent framework, enabling new comprehensive studies. Here, we apply unsupervised classification techniques (e.g. Gaussian Mixture Modeling) to the new comprehensive Weddell Gyre dataset to look for coherent regimes in temperature and salinity. We find that, despite not being given any latitude or longitude information, unsupervised classification algorithms identify spatially coherent thermohaline domains. The highlighted features include the Antarctic Circumpolar Current, the central Weddell Gyre, and the Antarctic Slope current; we also find potential signatures of the inflow of Weddell Deep Water and export pathways of Antarctic Bottom Water. We show how varying the statistical, machine learning derived representations of the data can reveal different physical structures and circulation pathways that are relevant to the delivery of relatively warm waters to the higher-latitude seas and their associated ice shelves.

The mid-to-high latitude North Atlantic features cold temperature anomalies on interannual timescales. For example, in 2015 a region of open ocean southwest of Greenland reached a record low temperature relative to the period 1880-2015. Such rapid drops in upper ocean heat content have been linked to impacts on the North Atlantic Oscillation and European climate (e.g. heat waves induced by changing atmospheric circulation patterns). Despite their potential importance for regional climate, the specific mechanisms that induce these interannual cold anomalies are still not well understood. In particular, the relative importance of changes in surface forcing compared with upwelling of deep ocean cold anomalies (i.e. those below 500 m) in establishing the 2015 cold anomaly is a topic of intense debate. Here we use an observationally-constrained ocean model in adjoint mode to calculate the sensitivities of upper ocean heat content to local and remote surface forcing. Adjoint methods allow us to quantify the relative contributions of wind stress and net heat flux in producing the 2015 cold anomaly. Wind stress contributes to the cold anomaly via both (1) strengthening surface latent and sensible heat losses and (2) inducing changes in ocean circulation. Net heat flux contributes to the cold anomaly by inducing heat loss in both local and upstream waters. We also use adjoint methods to calculate (1) the source waters that contributed to the cold anomaly and (2) regions that may have contributed to the cold anomaly by inducing changes in synoptic-scale ocean circulation. Furthermore, we examine the large-scale context by calculating the sensitivities of subpolar gyre heat content to surface forcing and the ocean state. Our results suggest that surface forcing, particularly the extreme heat loss event in the winter of 2013-2014, played a dominant role in producing the 2015 cold anomaly.

Ice sheet melting into the Southern Ocean can change the formation and properties of the Antarctic Bottom Water (AABW). Climate models generally mimic ice sheet melting by adding uniformly-distributed freshwater fluxes in the Southern Ocean. Uniform fluxes misrepresent the heterogeneous Antarctic ice sheet melting patterns, and could bias AABW representation in models. We use a global ocean and sea-ice model to explore whether the spatial distribution and increases in freshwater fluxes can alter AABW properties, formation, and the Antarctic sea-ice area. We find that a realistic spatially varying flux sustains AABW with higher salinities compared to simulations with uniform meltwater fluxes. Finally, we show that a ~ 20% increase in ice sheet melting can trigger AABW freshening and Antarctic sea-ice expansion rates similar to those observed in the Southern Ocean since 1980, suggesting that the increasing Antarctic meltwater discharge can drive the observed AABW freshening and the Antarctic sea-ice expansion.