A wealth of new climate model simulations have recently become available through the Coupled Model Intercomparison Project, Phase 6 (CMIP6). Evaluation of the representation of the Antarctic ocean across CMIP6 models is critical: projections of near-ice sheet temperature change will be used as input into sea level projections, and previous CMIP ensembles show substantial biases with a wide inter-model and inter-region spread. However, the ocean over the Antarctic continental shelf remains sparsely sampled, posing challenges for model-data comparison. Here, we assess a new clustering-based, grid-independent, methodology to identify and compare regional water masses, focusing on the Pacific sector of the Antarctic continental shelf. We find that temperature is insufficient to differentiate water masses, given the complexity and diversity of hydrographic profiles on the continental shelf. In contrast, clustering approaches applied to World Ocean Atlas 2018 temperature and salinity profiles identify “source” and “mixed” regimes that have a physically interpretable basis. For example, meltwater-freshened coastal currents in the Amundsen Sea, and High Salinity Shelf Water formation regions in the western Ross Sea, emerge naturally from the algorithm. We compare the location and properties of observed regimes to those found in the modern hydrographic state of the Community Earth System Model, version 2. Although CESM2 biases can be substantial, the locations of distinct regimes, and inter-cluster differences in water mass properties, are relatively consistent with observations. Differences in the locations and properties of hydrographic regimes are consistent with those expected from missing or poorly-represented physical processes (e.g. katabatic winds, ice shelf basal melting). We note other applications of this method, including the assessment of seasonal variability, and model-data comparison with different CMIP6 simulations and higher resolution regional ocean models.

Improving constraints on the basal ice/bed properties is essential for accurate prediction of ice-sheet grounding-line positions and stability. Furthermore, the history of grounding-line positions since the Last Glacial Maximum has proven challenging to understand due to uncertainties in bed conditions. Here we use a 3D full-Stokes ice-sheet model to investigate the effect of differing ocean bed properties on ice-sheet advance and retreat over a glacial cycle. We do this for the Ekström Ice Shelf catchment, East Antarctica. We find that predicted ice volumes differ by >50%, resulting in two entirely different catchment geometries triggered exclusively by variable ocean bed properties. Grounding-line positions between simulations differ by >100% (49 km), show significant hysteresis, and migrate non-steadily with long quiescent phases disrupted by leaps of rapid migration. These results highlight that constraints for both bathymetry and substrate geologic properties are urgently needed for predicting ice-sheet evolution and sea-level change.

Clouds in the tropical western Pacific are dominated by reflective deep convective cores with gradually thinning trailing anvil clouds, which play a crucial role in determining tropical cloud radiative effects. The microphysical controls of the thinning process and its changes when subjected to a future warmer climate are still very uncertain.We use the high resolution version of the Exascale Earth System Model (E3SM) to study the thinning process in present day and future climate. We apply Lagrangian forward trajectories starting at peaks of convective activity of the detected mesoscale convective systems (MCS) and track detrained ice crystals to better understand the processes controlling the transition of a thick detrained anvil cloud into a thin cirrus cloud. The trajectories are computed offline from the 1-hourly model-calculated velocity fields and ice crystal sedimentation velocities. The modeled MCS in present day climate have a comparable time evolution to those observed by Himawari geostationary satellite data, with an average lifetime of about 10-15 hours, which accounts only for the optically thick part of the cold cloud shield. However, E3SM fails to simulate the strongest storms, which is reflected by an underestimation of albedo and overestimation of outgoing longwave radiation. The analysis of ice sources (detrainment, vapor deposition, new nucleation events) and sinks (sublimation, aggregation, sedimentation) along trajectories highlights the crucial role of the balance between depositional growth and precipitation formation for the maintenance of aging anvil clouds. Interestingly, deposition of ice on detrained ice crystals contributes to the majority of the upper tropospheric ice mass. On the other hand, about 80% of the initial cloud mass is removed in the form of precipitation within the first 10 hours of the detrainment event, changing its radiative effect from net negative to net positive. The future climate simulation shows an increase in storm frequency and intensity, an increase in ice water content and albedo in convective cores and thick anvils. The trajectory calculations reveal a 15% decrease in cloud lifetime due to climate change, suggesting a decrease in thin high clouds due to a higher precipitation efficiency and a shift to more negative net cloud radiative effects.

Ethiopia’s socioeconomic development is strongly dependent on both its natural resources and hydroclimatic dynamics. Current and projected effects of climate change and variability in the Horn of Africa pose an enormous challenge to the country’s water resources management. We modeled multi-basin runoff scenarios in the country by calibrating statistical models first followed by extrapolation of the regressed functions into a future data domain under assumptions of stationarity. Precipitation and average near-surface air temperature predictors were used to calibrate Generalized Linear Models (GLM) to project 2011-2070 monthly runoff in a high-emission scenario (RCP 8.5) for selected General Circulation Models (GCM). Gridded fields of downscaled and bias-corrected precipitation, Tmax and Tmin for 10 CMIP5 GCMs were obtained from the NASA NEX-GDDP database. Hydrologic simulations from the NASA Land Data Assimilation System (LDAS) were used as proxies of observational basin response. Noah-MP’s climate forcings (CHIRPS precipitation and MERRA temperatures) were used to perform additional bias-correction over basin-averaged predictors extracted from the NEX-GDDP ensemble models. Monthly mean estimates for precipitation/temperature projections showed wetter/warmer conditions than the baseline for almost all regions. 2011-2040 July temperature climatology in most GCMs exhibited the strongest warming (> 1.5C o) in Central Ethiopia and it gradually decreased northwards and southwards. Correlation analysis showed that precipitation variations explain most of runoff variability during the rainy seasons. Future GLM runoff estimates suggest a generalized national increase of mean annual water supply when compared with historical LDAS, although spatio-temporal differences were observed across the country. The mentioned hydrological gains are driven by spatially distributed changes in precipitation with the biggest positive trends in the southeastern region followed by moderate precipitation increases in the Central Highlands and neutral changes in the Northwest. Few GCMs (e.g., GFDL-CM3) project drier conditions in the rainy seasons and a slight decrease in the mean annual runoff for most basins. The wettest model in the Abay basin, IPSL-CM5A-LR, predicts 15% increase in annual runoff when compared to historical averages.

The bottom topography of ridged sea ice differs largely from that of other sea ice types. The form drag on ridge keels plays an important role affecting sea ice drift and deformation. We have carried out laboratory experiments and numerical simulations for a ridge model in a flume in order to better understand the characteristics of the form drag. The experimental setup covered both laminar and turbulent conditions. The local form drag coefficient of a keel, Cd, varied with the keel depth h and slope angle α in the turbulent regime. The numerical model extended the experimental results to independence of the water depth in order to achieve an analogy for ocean conditions. The results showed Cd= 0.68ln(α/7.8),R2= 0.998, 10˚ ≤ α≤ 90˚, Cd ranging from 0.14 to 1.66, when keel depth is much smaller than mixed layer depth. In the Arctic Ocean, keel slope angles are within the range of 10˚–50˚ where Cd increases monotonously and becomes the dominant part of the total ice-water drag coefficient when α ≥ 20˚. When h/Lr (the ratio of keel depth to spacing) was high (h/Lr>0.01), the ratio of air-ice to ice-water drag coefficient first decreased and then increased with α and reached the minimum at α ≈ 30˚. The variation of Cd with α (10˚–50˚) affects the momentum transfer of drifting sea ice, and we suggest that Cd under ridged sea ice to be tuned to 0.14–1.26 in multi-category sea ice models.

The development of atmospheric parameterizations based on neural networks is often hampered by numerical instability issues. Previous attempts to replicate these issues in a toy model have proven ineffective. We introduce a new toy model for atmospheric dynamics, which consists in an extension of the Lorenz'63 model to a higher dimension. While neural networks trained on a single orbit can easily reproduce the dynamics of the Lorenz'63 model, they fail to reproduce the dynamics of the new toy model, leading to unstable trajectories. Instabilities become more frequent as the dimension of the new model increases, but are found to occur even in very low dimension. Training the neural network on a different learning sample, based on Latin Hypercube Sampling, solves the instability issue. Our results suggest that the design of the learning sample can significantly influence the stability of dynamical systems driven by neural networks.

Subtropical anticyclones and midlatitude storm tracks are key components of the large-scale atmospheric circulation. Focusing on the southern hemisphere, the seasonality of the three dominant subtropical anticyclones, situated over the South Pacific, South Atlantic and South Indian Ocean basins, has a large influence on local weather and climate within South America, Southern Africa and Australasia, respectively. Generally speaking, sea level pressure within the southern hemisphere subtropics reaches its seasonal maximum during the winter season when the southern hemisphere Hadley Cell is at its strongest. One exception to this is the seasonal evolution of the South Pacific subtropical anticyclone. While winter maxima are seen in the South Atlantic and South Indian subtropical anticyclones, the South Pacific subtropical anticyclone reaches its seasonal maximum during local spring with elevated values extending into summer. In this study we investigate the hypothesis that strength of the austral summer South Pacific subtropical anticyclone is largely due to heating over the South Pacific Convergence Zone. Using reanalysis data, and AGCM added cooling and heating experiments to artificially change the strength of diabatic heating over the South Pacific Convergence Zone, our results show that increased heating triggers a Rossby wave train over the Southern Hemisphere mid-latitudes by increasing upper-level divergence. The propagating Rossby wave train creates a high-low sea level pressure pattern that projects onto the center of the South Pacific Subtropical Anticyclone to intensify its area and strength. The southern hemisphere storm tracks also shift poleward due to increased heating over the South Pacific Convergence Zone.

This study aims to quantify the impacts of ocean coupling on simulated and projected tropical cyclone (TC) precipitationin the Northern Hemisphere. We used global climate model (GCM) simulations over 1950-2050 from the High Resolution Model Intercomparison Project (HighResMIP) and compared its fully coupled atmosphere-ocean GCMs (AOGCMs) with atmosphere-only GCMs (AGCMs). We find that ocean coupling generally leads to decreased TC precipitation over ocean and land. Large-scale sea surface temperature (SST) biases are critical drivers of the precipitation difference, with secondary contributions from local TC-ocean feedbacks via SST cold wakes. The two driving factors, attributed to ocean coupling in the AOGCMs, influence TC precipitation in association with decreased TC intensity and specific humidity. The AOGCMs and AGCMs consistently project TC precipitation increases in 2015-2050 relative to 1950-2014 over ocean for all basins, and for landfalling TCs in the North Atlantic and western North Pacific.

Paleo and recent sea surface temperature (SST) measurements at six locations spanning the North Atlantic, from the northeastern North Atlantic off the British Isles to the Dry Tortugas in the southwest, were examined in order to determine whether a period of cooling was responsible for the die-off of elkhorn corals (Acropora palmata) on the reef off Broward County around six thousand years ago (6 Kya) and whether warming sea temperatures might contribute to their recovery. The paleo data show indications of a warm period between 13 Kya and 7 Kya, followed by cooling, probably due to orbital forcing arising from the coincidence of insolation maxima in the Milankovitch obliquity and axial precession cycles in the Northern hemisphere at that time, but the lack of paleo data in the immediate proximity of the reef makes it difficult to draw firm conclusions regarding the die-off of the corals. However, the marine SST data obtained from ships and buoys since 1870 raise questions about the presumed recent global warming. Annual average sea surface temperatures in the North Atlantic show remarkable stability and consistency with little or no change over the 146 years between 1870 and 2015, despite large seasonal and latitudinal variation in response to differences in solar irradiance.

By solving Laplace’s tidal equations along the equatorial Pacific thermocline, assuming a delayed-differential effective gravity forcing due to a combined lunar+solar (lunisolar) stimulus, we are able to precisely match ENSO periodic variations over wide intervals. The underlying pattern is difficult to decode by conventional means such as spectral analysis, which is why it has remained hidden for so long, despite the excellent agreement in the time-domain. What occurs is that a non-linear seasonal modulation with monthly and fortnightly lunar impulses along with a biennially-aligned “see-saw” is enough to cause a physical aliasing and thus multiple folding in the frequency spectrum. So, instead of a conventional spectral tidal decomposition, we opted for a time-domain cross-validating approach to calibrate the amplitude and phasing of the lunisolar cycles. As the lunar forcing consists of three fundamental periods (draconic, anomalistic, synodic), we used the measured Earth’s length-of-day (LOD) decomposed and resolved at a monthly time-scale [1] to align the amplitude and phase precisely. Even slight variations from the known values of the long-period tides will degrade the fit, so a high-resolution calibration is possible. Moreover, a narrow training segment from 1880-1920 using NINO34/SOI data is adequate to extrapolate the cycles of the past 100 years (see attached figure). To further understand the biennial impact of a yearly differential-delay, we were able to also decompose using difference equations the historical sea-level-height readings at Sydney harbor to clearly expose the ENSO behavior. Finally, the ENSO lunisolar model was validated by back-extrapolating to Unified ENSO coral proxy (UEP) records dating to 1650. The quasi-biennial oscillation (QBO) behavior of equatorial stratospheric winds derives following a similar pattern to ENSO via the tidal equations, but with an emphasis on draconic forcing. This improvement in ENSO and QBO understanding has implications for vastly simplifying global climate models due to the straightforward application of a well-known and well-calibrated forcing. [1] Na, Sung-Ho, et al. “Characteristics of Perturbations in Recent Length of Day and Polar Motion.” Journal of Astronomy and Space Sciences 30 (2013): 33-41.

Why would hundreds of scientists from around the world freeze a ship in Arctic sea ice for an entire year, braving subzero temperatures and months of polar darkness? This may sound like a fictional adventure movie plot, but from September 2019 through October 2020, the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) Arctic research expedition did just this. Currently, the Arctic is warming twice as fast as the global average (a phenomenon known as Arctic amplification) and due to a lack of observations, there is considerable uncertainty in climate models projecting the Arctic climate of the future. The MOSAiC expedition aims to better understand the changing Arctic climate system by gathering data from ground zero over a full seasonal cycle to augment satellite observation data. Using the expedition as an engagement hook, scientists and curriculum developers developed a high school earth science curriculum anchored by the phenomenon that climate scientists are actively trying to explain: Arctic amplification. The curriculum follows the model-based inquiry instructional framework where each lesson provides students with learning experiences (e.g., virtual reality tours of MOSAiC field sites, analyzing authentic Arctic satellite datasets) that relate back to the phenomena. Focusing on explaining natural phenomena provides an authentic context for students to learn and apply scientific understanding, which research shows can help engage students in NGSS scientific practices. Here we present an overview of the learning sequence using refinement of mental models throughout the unit and present preliminary results from pre-post assessments from two educator workshops (~100 teachers) that show that participants’ understanding of Earth’s climate system improved significantly after engaging with the curriculum. Based on these results, we expect this curriculum to be an important tool in engaging students in Earth’s systems thinking.

During recent droughts in North Carolina, various audiences have articulated needs for information that explains current or anticipated impacts, droughts’ geographic extent and timing, and how the State monitors drought. This is despite there being a regular process in place to evaluate statewide conditions and seemingly abundant information available through federal, state, and local agency websites; media outlets; and other channels. This presentation provides findings from a research project designed to improve the availability, understandability, and usability of drought communications products for North Carolina audiences, focusing on the US Drought Monitor map of North Carolina as an example. The North Carolina Drought Management Advisory Council (DMAC) technical committee has met weekly to assess drought conditions since the 1990s and has recommended the state’s drought designations to the US Drought Monitor since 2000. The DMAC recommendations typically align with the weekly USDM map. Through surveys, focus groups, usability studies, and other engagement methods, we collected information from groups such as extension agents and water utility staff about 1) their communications preferences - resources that are concise, easily readable, and readily shareable through email, listservs, and social media - and 2) infographic prototypes created to address those preferences. User feedback on the prototypes informed iterative refinements to their content and design and provided information about their potential use for communications and management decisions. Ultimately, understanding the monitoring process and how drought designations are made was a key factor affecting the extent to which extension and other communication professionals apply, share, and value the information produced by monitoring groups and scientific agencies. This research suggests that addressing transparency questions can support efforts to communicate complex problems, such as drought.

Data-model comparisons are common when addressing (paleo)climate questions. Many applications require deriving continuous surface fields of scalar variables from a set of irregularly distributed data points, typically for model validation against data or data-derived model input as initial or boundary conditions. While various interpolation techniques and interfaces exist, few can simultaneously: (1) interpolate across local to global spatial scales, (2) perform anisotropic interpolation using the spatial structure derived from the data instead of an assumed one, and (3) explicitly derive uncertainty in the interpolated fields due to both data density and measurement error. We present a standalone interpolation toolbox including a graphical user interface (GUI), which is aimed at the general earth science community. It uses a kriging algorithm whose distance metric is the geodesic on an oblate spheroid, be it the WGS-84 reference ellipsoid for applications on the surface of the Earth, or an equivalent ellipsoid with varying radii for interpolation on vertical levels above the surface. While kriging algorithms exist that perform interpolation on such non-Euclidean distances, they do not provide a check for conditionally negative semi-definiteness (CNSD) of the variogram matrix, which is a requisite for the kriging method. Since mathematical theory of kriging on spheroids or ellipsoids has not yet provided a set of authorized variance-distance functions, we incorporated a numerical check for CNSD condition for each data realization and variance-distance modeling scheme. The GUI will allow the user a high degree of customization. Preliminary results are promising, with robust results for isotropic interpolation. The derivation of CNSD variogram matrices for anisotropic interpolation remains the major challenge of the project. When completed, ClimAG-Krigger will provide the community with an easy-to-use, robust tool for anisotropic global kriging that will be specifically tailored for (paleo)climate applications.

Previous approaches to modify the surface albedo of Arctic ice have been proposed to slow the rate of ice melt or to increase ice thickness. (Seitz 2011, Desch 2018, Field 2018) Sea ice, glacial ice, and ice-covered thermokarst lakes are all known to melt aided by surface albedo feedback loops. In this process, melting of snow and/or the formation of melt ponds on the surface of the ice causes a lowering of surface albedo, which causes more absorption of sunlight, further warming the ice and increasing the rate of melt. In this study on a freshwater pond, we demonstrate the real-time dynamics of melting and a reduction of ice melt rate by 26% via surface albedo modification.

Since its launch, in September 2018, ICESat-2’s Advanced Topographic Laser Altimeter System (ATLAS) has collected high-resolution measurements of Arctic sea ice by sampling the surface every 70 cm along-track. We utilize the high-resolution capabilities of ATLAS with a novel algorithm called the University of Maryland-Ridge Detection Algorithm (UMD-RDA) to investigate sea ice topography across a range of scales. Applying the UMD-RDA to the ATL03 Global Geolocated Photon product we measure surface roughness and derive the frequency, height, width, and angle of individual pressure ridge sails. Aggregating data from multiple orbit crossings per day we investigate ridge characteristics at length-scales varying from 1 km (individual floes) to the pan-Arctic scale (central Arctic Ocean). Here, we present an evaluation of pressure ridge characteristics during the winter seasons of 2018/19, 2019/20, and 2020/21, comparing results from distinct regions with varying ice conditions. Near-coincident, independent observations of pressure ridges with Operation IceBridge (OIB) Airborne Topographic Mapper (ATM) lidar data, OIB near-coincident Continuous Airborne Mapping By Optical Translator (CAMBOT) high-resolution (~15 cm) optical imagery, and WorldView high-resolution (~30 cm) panchromatic satellite imagery are used to evaluate the accuracy of our ICESat-2 ridge detection scheme. There are many potential use-cases for a high-resolution sea ice topography data product within the community, ranging from navigational hazard mitigation to ecological studies of marine mammal habitats. We discuss plans for releasing these data products and discuss the improvements such data would make within high-resolution sea ice models.

The latest generation of coupled models, the sixth Coupled Models Intercomparison Project (CMIP6), is used to study the changes in the El Niño Southern Oscillation (ENSO) in a warming climate. For the four future scenarios studied, the sea surface temperature variability increases in most CMIP6 models, but to varying degrees. This increase is linked to a weakening of the east-west temperature gradient in the tropical Pacific Ocean, which is evident across all models. Just as in previous generations of climate models, we find that many characteristics of future ENSO remain uncertain. This includes changes in dominant timescale, extra-tropical teleconnection patterns and amplitude of El Niño and La Niña events. For models with the strongest increase in future variability, the majority of the increase happens in the Eastern Pacific, where the strongest El Niño events usually occur.

Since its formation in 2015, the National Centers for Environmental Information (NCEI) has used disparate, legacy systems spread across several IT networks of the National Environmental Satellite, Data, and Information Service (NESDIS) to fulfill its data-stewardship functions. As part of its modernization and consolidation of these functions, NCEI implemented Common Ingest as the functional component that ingests approximately 200 data streams every month into its enterprise archival information system. In parallel, NESDIS completed the Secure Ingest Gateway Project (SIGP), a pilot project to establish standard-enterprise secure methods for NESDIS and the rest of the National Oceanic and Atmospheric Administration (NOAA) to receive data in a cloud environment from their external partners. SIGP is now transitioning to operations as the Operational Secure Ingest Service (OSIS), which will be the on-ramp to NCEI’s “Common Ingest” functionality when it too moves to the cloud. In addition, this ingest function will populate and use a cloud-based metadata catalog, which will be the beating heart of the NESDIS and NCEI information systems in the cloud environment. The vision is to scale their ingest of environmental data to keep pace with its ever increasing volume, veracity, variety, and velocity. In this presentation to the ocean data community, the authors describe NESDIS and NCEI’s challenges and successes with the implementation of the ingest function of their archival information system in a cloud environment.

The latitudinal position of the subtropical jet over the Himalayas (Himalayan jet latitude or HJL) controls the region’s climate during winter and spring by guiding moisture-delivering storms. Here we use the Community Earth System Model-Last Millennium Ensemble to diagnose forced trends in HJL during the past millennium. During 850-1849, there is a weak equatorward trend in winter HJL. In contrast, the spring HJL has a relatively larger poleward trend, and increases in both variance and frequency of poleward/equatorward excursions. We demonstrate changes in orbital precession reduced the thermal gradient between tropical and subtropical Asia, shifting the spring HJL poleward. During 1850-2005, the spring HJL exhibits no trend due to compensating influences from orbital and anthropogenic greenhouse gas forcings. These findings suggest it is essential climate models properly simulate the effects of and potential interactions between orbital forcing and anthropogenic factors to accurately project Himalayan jet variability and associated storm tracks.

The full length of Parker Ice Tongue on the Victoria Land Coast, Antarctica, calved in March 2020. Calving of this magnitude (18 km) is not previously seen for this location. The mean growth rate (189 m yr-1) indicates that it is now at a historic minimum for at least the last 165 years. The 2020 calving occurred during a complete breakout of the land-fast sea ice. Here we link seasonal changes in ice velocity to the land-fast sea ice extent. With Summer/winter increase/decrease in velocity correlates with decrease/increase in land-fast sea ice extent (-0.62 with R-squared of -0.39). Although Parker Ice Tongue was relatively small compared to other ice tongues in the region, its sensitive behaviour highlights the vulnerability of ice tongues to a changing ocean environment, and poses questions about the future stability of larger floating ice masses if land-fast sea ice extent decreases more broadly in the future.

Global change is a change in the planetary energy balance. It is usually expressed as a change in near-surface (2 m) air temperature (Ta), but changes to Ta represent only part of the atmospheric energy balance, which includes specific humidity (q) and more. We analyzed MERRA-2 reanalysis data and 15 Atmospheric Model Intercomparison Project (AMIP) models over the 1980-2014 period. Some 41%, 37%, and 49% of the near-surface atmosphere showed significant increases in ET, ESH, and E, respectively. The average increase in ET (ESH) was 10.6 J kg−1 year−1 (11.5 J kg−1 year−1) but AMIP models estimated that ET (14.5 J kg−1 year−1) exceeded ESH (13.7 J kg−1 year−1). Global near-surface Ta would have increased at more than twice the observed rate if energy was not partitioned into latent heat. Results demonstrate the critical role that q plays in recent changes to near-surface atmospheric energy.

Quantitative knowledge about the burial of sedimentary components at the seafloor has wide-ranging implications in ocean science, from global climate to continental weathering. The use of 230 Th-normalized fluxes reduces uncertainties that many prior studies faced by accounting for the effects of sediment redistribution by bottom currents and minimizing the impact of age model uncertainty. Here we employ a recently compiled global dataset of 230 Th-normalized fluxes with an updated database of seafloor surface sediment composition to derive global maps of the burial flux of calcium carbonate, biogenic opal, total organic carbon (TOC), non-biogenic material, iron, mercury, and excess barium (Baxs). The spatial patterns of burial of the major components are mainly consistent with prior work, but the new quantitative estimates allow evaluations of global deep-sea burial. Our integrated deep-sea burial fluxes are 136 Tg C/yr CaCO3, 153 Tg Si/yr opal, 20Tg C/yr TOC, 220 Mg Hg/yr, and 2.6 Tg Baxs/yr. Sedimentary Fe fluxes reflect a mixture of sources including lithogenic material, hydrothermal inputs and authigenic phases. The fluxes of some commonly used paleo-productivity proxies (TOC, biogenic opal, and Baxs) are not well-correlated geographically with satellite-based productivity estimates. Our new compilation of sedimentary fluxes provides more detailed information on burial fluxes, which should lead to improvements in the understanding of how preservation affects these paleoproxies.

Over the last century, runoff from farms and cities, along with land cover and land use changes, have drastically altered the mass balance of nutrients in aquatic systems, affecting both their ecological functioning and the living communities they support. Here we present the results of a multi-year, long-term study designed to assess the control of land-use and hydrology on nutrient fate and transport within a mixed land-use watershed in north-central Ohio. A total of 64 streams (with a mix of urban, cropland, pasture, and forest catchments) have been sampled periodically since the summer of 2008. Hydrological conditions during the study period exhibited marked seasonality, with usually dry winter seasons (average ppt: 23.5±7.4 cm) and wet spring seasons (average ppt: 34.5±8.1 cm). Runoff generation in response to precipitation events is faster in streams draining developed catchments and slowest in forested streams, where runoff is generated only by events > 10 mm/day. Hydrologic connectivity in the watershed appear to be limited, since only about 25% of precipitation inputs were translated into quick flow. There is a significant, positive correlation between runoff and nutrient concentrations (R2 values are: 0.40 for streams draining urban landscapes, 0.34 for forested streams, 0.30 for cropland, and 0.28 for pastureland). We also observed significant inter-annual and seasonal variations on both DIN (p = 0.02) and PO4 concentrations (p < 0.01). Compared to dry years, nutrient fluxes during wetter years are, on average, 16% higher in urban catchments and 47% higher in forested catchments, but 32% lower in pasture-dominated catchments. Baseflow is responsible for only between 20-30% of the annual nutrient export from the watershed.

The moisture sources of precipitation in the Tianshan Mountains, one of the regions with the highest precipitation in Central Asia during 1979-2017 are comprehensively and quantitatively summarized by using a Lagrangian moisture source detection technique. Continental sources provide about 93.2\% of the moisture for precipitation in the Tianshan Mountain, while moisture directly from the ocean is very limited, averaging only 6.8\%. Central Asia plays a dominant role in providing moisture for all sub-regions of the Tianshan Mountains. For the Western Tianshan, moisture from April to October comes mainly from Central Asia (41.4\%), while moisture from November to March is derived primarily from Western Asia (45.7\%). Nearly 13.0\% of moisture to precipitation for Eastern Tianshan in summer originates from East and South Asia, and the Siberia region. There is a significant decreasing trend in the moisture contribution of local evaporation and Central Asia in the Eastern Tianshan during winter. The contribution of moisture from Europe to summer precipitation in the Central and Eastern Tianshan and the contribution of the North Atlantic Ocean to summer precipitation in the Northern, Central, and Eastern Tianshan also exhibit a decreasing trend. The largest increase in moisture in Western Tianshan stems from West Asia during extreme winter precipitation months. Europe is also an important contributor to extreme precipitation in the Northern Tianshan. The moisture from East and South Asia and Siberia during extreme precipitation months in both winter and summer is significantly enhanced in the Eastern Tianshan.

The paleolatitude distribution of paleoclimate proxies and contintential landmass is an important constraint for modeling and understanding paleoclimate. True polar wander (TPW), which can produce large, potentially rapid changes in paleolatitude, is a necessary component in paleolatitude reconstructions. Prior workers, e.g., van Hinsbergen et al. (2015), have created paleolatitude frameworks from global continental apparent polar wander paths (APWPs) drawn from running means of continental paleomagnetic studies (e.g., Torsvik et al. 2012). These are limited by the precision of the running mean, poor age resolution amplified by use of a running mean, and the uncertainties and the unknowns of ancient plate motion circuits. In particular, the Pacific Plate is linked to the global plate circuit through Antarctica. Early paleomagnetic tests of this circuit (Suarez & Molnar, 1980; Gordon & Cox 1980; Acton & Gordon 1994) indicated inconsistency of the circuit with paleomagnetic data such that the reconstructed Pacific plate did not move as far north as indicated by its indigenous paleomagnetic data. Some later work has asserted, however, that updated paleomagnetic data and plate reconstructions no longer indicate the inconsistency found before (Doubrovine & Tarduno 2008). Important progress has also been made in estimating the motion between East and West Antarctica from seafloor data (e.g. Granot & Dyment 2018). We revisit these questions here. We test the predictions of the global paleolatitude framework at points across the Pacific Plate using a well-constrained observed APWP constructed from indigenous Pacific plate data from skewness analysis of marine magnetic anomalies (Schouten & Cande 1976; Cox & Gordon 1980) and locations of paleo-equatorial sediments (Moore et al. 2004; Woodworth & Gordon 2018), which uniquely determine Pacific Plate paleolatitude independent of plate circuits. The misfit between the observed and predicted paleolatitude varies with longitude across the plate and is as large as ~10±3°, with the largest misfit occurring between 40 and 60 Ma. Implications of this discrepancy will be discussed and an improved paleolatitude framework for the Pacific plate will be presented.