A document by Clara Orbe. Click on the document to view its contents.

A document by Clara Orbe. Click on the document to view its contents.

These Earth Energy Budgets (EEBs) came to prominence in 1997 when Kiehl and Trenberth produced their EEB known commonly as KT97. They have regularly come under attack. Primarily they show the Earth emitting 300% more radiation than it receives from the Sun. This energy is being generated out of nothing and violates the 1 st Law of Thermodynamics. They also show the Sun shining on the dark side of the Earth, something that just doesn't happen. All the radiation data in these EEBs, with the exception of Long Wave Down LWD and Long Wave Up LWU infrared IR radiation at the surface, have been divided by 4. This shows the Sun shining equally on all 4 quadrants of the Earth. This has the effect of having the Earth emitting 300% more radiation than it receives from the Sun. This 300% extra radiation is supposedly being generated out of nothing by a greenhouse effect GHE in the atmosphere. It seems apparent that this divide by 4 system is being used as a means of justifying the GHE theory. IR radiation is 100 times less energetic than visible radiation. That means the 322 W/m 2 of IR LWD is the equivalent of 3.22 W/m 2 of visible or Short Wave Down SWD radiation from the Sun. Since it appears these EEBs are being used to calibrate climate models, it has become necessary to review these EEBs and that in turn led to it becoming necessary to generate a new Earth Energy Budget to bring some realism back into them. This paper produces a new Earth Energy budget based on measured data. The Earth receives 1,361 W/m 2 of Short Wave Down SWD solar radiation at the top of atmosphere TOA and 1,361 W/m 2 of Short Wave Up SWU and LWU arrive back at the TOA. 589 W/m 2 of solar radiation is absorbed in the surface and 589 W/m 2 of LWU, latent heat and thermals is emitted by the surface. There is no mystery radiation being generated in the atmosphere and the budget is in balance.

It is recapitulated that the gravitational potential energy that is conserved along the neutral surfaces needs two terms, one from buoyancy and the other from gravity. I also show a mathematical identity for the time change of this gravitational potential energy which can be interpreted as exchange of energy amongst kinetic, internal, and gravitational potential forms. Movements along the neutral surface conserve the gravitational potential energy and it is shown that not only conversions into and out of the gravitational potential energy balance, but that each of the conversion terms is zero.

Insufficient in-situ observations from the Antarctic marginal ice zone limit our understanding and description of relevant mechanical and thermodynamic processes that regulate the seasonal sea ice cycle. Here we present high-resolution thermal images of the ocean surface and complementary measurements of atmospheric variables that were acquired underway during one austral winter and one austral spring expedition in the Atlantic and Indian sectors of the Southern Ocean. Skin temperature data and ice cover images were used to estimate the partitioning of the heterogeneous surface and calculate the heat fluxes to compare with ERA5 reanalyses. The winter marginal ice zone was composed of different but relatively regularly distributed sea ice types with sharp thermal gradients. The surface-weighted skin temperature compared well with the reanalyses due to a compensation of errors between the sea ice fraction and the ice floe temperature. These uncertainties determine the dominant source of inaccuracy for heat fluxes as computed from observed variables. In spring, the sea ice type distribution was more irregular, with alternation of sea ice cover and large open water fractions even 400 km from the ice edge. The skin temperature distribution was more homogeneous and did not produce substantial uncertainties in heat fluxes. The discrepancies relative to reanalysis data are however larger than in winter and are attributed to biases in the atmospheric variables, with the downward solar radiation being the most critical.

Studies of ocean surface transport often invoke the “Eulerian-mean hypothesis”: that wave-agnostic general circulation models neglecting explicit surface waves effects simulate the Eulerian-mean ocean velocity time-averaged over surface wave oscillations. Acceptance of the Eulerian-mean hypothesis motivates reconstructing the total, Lagrangian-mean surface velocity by adding Stokes drift to model output. Here, we show that the Eulerian-mean hypothesis is inconsistent, because wave-agnostic models cannot accurately simulate the Eulerian-mean velocity if Stokes drift is significant compared to the Eulerian-mean or Lagrangian-mean velocity. We conclude that Stokes drift should not be added to ocean general circulation model output. We additionally show the viability of the alternative “Lagrangian-mean hypothesis” using a theoretical argument and by comparing a wave-agnostic global ocean simulation with an explicitly wave-averaged simulation. We find that our wave-agnostic model accurately simulates the Lagrangian-mean velocity even though the Stokes drift is significant.

Passive Aquatic Listeners (PALs) have been increasingly deployed to collect minute-scale surface oceanic rainfall and wind information, with a sampling area similar to the spaceborne sensor footprints. This provides an unprecedented opportunity to validate satellite precipitation products over oceans. This study evaluates the Global Precipitation Climatology Project (GPCP) daily products, including the widely-used GPCP v1.3 and the newly released GPCP v3.2, over oceans using 58 PALs as references. The study shows that the GPCP performance depends on time scale, region, and rainfall intensity. The two versions of GPCP perform similarly at multi-year and monthly scales, while GPCP v3.2 shows substantial improvements in representing rain occurrence and rain intensity at daily scale. The results also highlight the challenge of precipitation measurement over certain regions such as the tropical Northeastern Pacific and extratropical North Pacific, where both versions of the GPCP products perform similarly but exhibit noticeable differences compared to PAL observations.

As a contribution to the Regional Carbon Cycle Assessment and Processes phase 2 (RECCAP2) project, we present synthesized estimates of Arctic Ocean sea-air CO2 fluxes and their uncertainties from 8 surface ocean pCO2-observation products, 18 ocean biogeochemical hindcast and data assimilation models and 6 atmospheric inversions. For the period of 1985−2018, the Arctic Ocean was a net sink of CO2 of 116 ± 4 TgC yr−1 in the pCO2 products and 92 ± 30 TgC yr−1 in the models. The CO2 uptake peaks in late summer and early autumn, and is low in winter when sea ice inhibits sea-air fluxes. The long-term mean CO2 uptake in the Arctic Ocean is primarily caused by steady-state fluxes of natural carbon (70 ± 15 %), and enhanced by the atmospheric CO2 increase (19 ± 5 %) and climate change (11 ± 18 %). The annual mean CO2 uptake increased from 1985 to 2018 at a rate of 31 ±13 TgC yr−1dec-1 in the pCO2 products and 10 ± 4 TgC yr−1dec-1 in the models. Moreover, 77 ± 38 % of the trend in the net CO2 uptake over time is caused by climate change, primarily due to rapid sea ice loss in recent years. Both, the mean CO2 uptake and the trend, is substantially weaker in the atmospheric inversions. Uncertainties across all estimates are large, in the pCO2 products because of scarcity of observations and in the models because of missing processes.

A document by Bijit Kumar Kalita. Click on the document to view its contents.

Although ENSO and its global impacts through teleconnection have been known for decades, if and how the mean currents and mesoscale eddies in the Caribbean Sea are linked to ENSO remains an open question. Here, by analyzing satellite observations and an ocean reanalysis product, we found a close connection between mean currents, eddies in the Caribbean Sea and ENSO on interannual timescales. Strong El Niño events result in enhanced north-south sea surface height (SSH) differences and consequently stronger mean currents in the Caribbean Sea, and the opposite happens during La Niña events. The eddy kinetic energy (EKE) responses to ENSO via eddy-mean flow interaction, primarily through baroclinic instability, which releases the available potential energy stored in the mean currents to mesoscale eddies. Our results suggest some predictability of the mean currents and eddies in the Caribbean Sea, particularly during strong El Niño and La Niña events.

A document by Keith Rodgers. Click on the document to view its contents.

Efforts to validate, monitor, and verify ocean-based carbon dioxide removal (CDR) will require a rich understanding of the ocean carbon system. Ocean observations anchor this understanding, but we know that some ongoing observations are precariously funded, that data products like SOCAT rely on volunteer effort, that regions essential to our understanding of the ocean carbon system are under-observed, and that some observation data is under-used. This presentation will be a progress report on our efforts to identify and document ocean carbon data flows using systematic literature reviews and examination of ocean data repositories. These data flows are essential to identify what data the scientific community already relies on; what data and observation gaps exist; and what data might be under-used. We examined variables of interest based on GOOS EOVs, including Oxygen (and supporting variables), Stable Carbon Isotopes (and supporting variables), Ocean Surface Stress (and supporting variables), and Ocean Surface Heat Flux (and supporting variables). Commonly observed supporting variables include O2, alkalinity, pCO2, pH, temperature, and near-surface air temperature, humidity, pressure, and wind speed.

Orbital precession has been linked to glacial cycles and the atmospheric carbon dioxide (CO2) concentration, yet the direct impact of precession on the carbon cycle is not well understood. We analyze output from an Earth system model configured under different orbital parameters to isolate the impact of precession on air-sea CO2 flux in the Southern Ocean – a component of the global carbon cycle that is thought to play a key role on past atmospheric CO2 variations. Here, we demonstrate that periods of high precession are coincident with anomalous CO2 outgassing from the Southern Ocean. Under high precession, we find a poleward shift in the southern westerly winds, enhanced Southern Ocean meridional overturning, and an increase in the surface ocean partial pressure of CO2 along the core of the Antarctic Circumpolar Current. These results suggest that orbital precession may have played an important role in driving changes in atmospheric CO2

For better projections of sea level rise, two things are needed: an improved understanding of the contributing processes and their accurate representation in climate models. A major process is basal melting of ice shelves and glacier tongues by the ocean, which reduces ice sheet stability and increases ice discharge into the ocean. We study marine melting of Greenland’s largest floating ice tongue, the 79° North Glacier, using a high-resolution, 2D-vertical ocean model. While our fjord model is idealized, the results agree with observations of melt rate and overturning strength. Our setup is the first application of adaptive vertical coordinates to an ice cavity. Their stratification-zooming allows a vertical resolution finer than 1 m in the entrainment layer of the meltwater plume, which is important for the plume development. We find that the plume development is dominated by entrainment only initially. In the stratified upper part of the cavity, the subglacial plume shows continuous detrainment. It reaches neutral buoyancy near 100 m depth, detaches from the ice, and transports meltwater out of the fjord. Melting almost stops there. In a sensitivity study, we show that the detachment depth depends primarily on stratification. Our results contribute to the understanding of ice–ocean interactions in glacier cavities. Furthermore, we suggest that our modeling approach with stratification-zooming coordinates will improve the representation of these interactions in global ocean models. Finally, our idealized model topography and forcing are close to a real fjord and completely defined analytically, making the setup an interesting reference case for future model developments.

Salt marshes are ecosystems with significant economic and environmental value. With accelerating rate in sea-level rise, it is not clear whether salt marshes will be able to retain their resilience. Field and numerical investigations have shown that storms play a significant role in marsh accretion and that they might be crucial to salt marsh survival to sea-level rise. Here we present the results from two studies (Pannozzo et al., 2021a,b; Pannozzo et al., 2022) that used numerical and field investigations to quantify the impact of storm surges on the sediment budget of salt marshes within different sea-level scenarios and to investigate how sediment transport pathways determine marsh response to storm sediment input. The Ribble Estuary, North-West England, was used as a test case. The hydrodynamic model Delft3D was used to simulate the estuary morpho-dynamics under selected storm surge and sea-level scenarios. In addition, sediment samples collected with a monthly frequency from different areas of the marsh were analysed with sediments collected from possible sources to integrate field observations with the numerical investigation of sediment transport pathways during stormy and non-stormy conditions. Results showed that, although sea-level rise threatens the estuary and marsh stability by promoting ebb dominance and triggering a net export of sediment, storm surges promote flood dominance and trigger a net import of sediment, increasing the resilience of the estuary and salt marsh to sea-level rise, with the highest surges having the potential to offset sea-level effects on sediment transport and sediment budget of the system. However, although storm sediment input resulted to be significant for the accretion of the marsh platform and particularly for the marsh interior, data showed that storms mainly remobilise sediments already present in the intertidal system and only to a minor extent transport new sediment from external sources.ReferencesPannozzo N. et al., 2021. Salt marsh resilience to sea-level rise and increased storm intensity. Geomorphology, 389 (4): 107825.Pannozzo N. et al., 2021. Dataset of results from numerical simulations of increased storm intensity in an estuarine salt marsh system. Data in Brief, 38 (6): 107336.Pannozzo N. et al., 2022. Sediment transport pathways determine the sensitivity of salt marshes to storm sediment input. In preparation.

The El Niño-Southern Oscillation (ENSO) in the equatorial Pacific is the dominant mode of global air-sea CO2 flux interannual variability (IAV). Air-sea CO2 fluxes are driven by the difference between atmospheric and surface ocean pCO2, with variability of the latter driving flux variability. Previous studies found that models in Coupled Model Intercomparison Project Phase 5 (CMIP5) failed to reproduce the observed ENSO-related pattern of CO2 fluxes and had weak pCO2 IAV, which were explained by both weak upwelling IAV and weak mean vertical DIC gradients. We assess whether the latest generation of CMIP6 models can reproduce equatorial Pacific pCO2 IAV by validating models against observations-based data products. We decompose pCO2 IAV into thermally and non-thermally driven anomalies to examine the balance between these competing anomalies, which explain the total pCO2 IAV. The majority of CMIP6 models underestimate pCO2 IAV, while they overestimate SST IAV. Thermal and non-thermal pCO2 anomalies are not appropriately balanced in models, such that the resulting pCO2 IAV is too weak. We compare the relative strengths of the vertical transport of temperature and DIC and evaluate their contributions to thermal and non-thermal pCO2 anomalies. Model-to-observations-based product comparisons reveal that modeled mean vertical DIC gradients are biased weak relative to their mean vertical temperature gradients, but upwelling acting on these gradients is insufficient to explain the relative magnitudes of thermal and non-thermal pCO2 anomalies.

Using Climate Forecast System Reanalysis (CFSR) data and numerical simulations, the impacts of the multi-scale sea surface temperature (SST) anomalies in the North Pacific on the boreal winter atmospheric circulations are investigated. The basin-scale SST anomaly as the Pacific Decadal Oscillation (PDO) pattern, a narrow meridional band of frontal-scale smoothed SST anomaly in the subtropical front zone (STFZ) and the spatial dispersed eddy-scale SST anomalies within the STFZ are the three types of forcings. The results of Liang-Kleeman information flow method find that all three oceanic forcings may correspond to the winter North Pacific jet changing with the similar pattern. Furthermore, several simulations are used to reveal the differences and detail processes of the three forcings. The basin-scale cold PDO-pattern SST anomaly first causes negative turbulent heat flux anomalies, atmospheric cooling, and wind deceleration in the lower atmosphere. Subsequently, the cooling temperature with an amplified southern lower temperature gradient and baroclinity brings a lagging middle warming because of the enhanced atmospheric eddy heat transport. The poleward and upward development of baroclinic fluctuations eventually causes the acceleration of the upper jet. The smoothed frontal- and eddy-scale SST anomalies in the STFZ cause comparable anomalous jet as the basin-scale by changing the upward baroclinic energy and E-P fluxes. The forcing effects of multi-scale SST anomalies coexist simultaneously in the mid-latitude North Pacific, which can cause similar anomalous upper atmospheric circulations. This is probably why it is tricky to define the certain oceanic forcing that leads to specific atmospheric circulation variation in observations

We developed a storm surge Ensemble Prediction System (EPS) for the Goro lagoon (GOLFEM-EPS) in the Northern Adriatic Sea. The lagoon is threatened every year by storm surge events with consequent risks for human life and economic losses. We show the advantages and limitations of an EPS with 45 members, using a very high-resolution unstructured grid finite element model. For five recent storm surge events, the EPS generally improves the forecast skill on the third forecast day compared to just one deterministic forecast, while they are similar in the first two days. A weighting system is implemented to compute an improved ensemble mean. The uncertainties regarding sea level due to meteorological forcing, river run-off, initial and lateral boundaries are evaluated, and the different forecasts are used to compose the EPS members. We conclude that the largest uncertainty is in the initial and lateral boundary fields at different time and space scales, including the tidal components.

Manganese (Mn) is an essential element for photosynthetic life, yet concentrations in Southern Ocean open waters are very low, resulting from biological uptake along with limited external inputs. At southern latitudes, waters overlying the Antarctic shelf are expected to have much higher Mn concentrations due to their proximity to external sources such as sediment and sea ice. In this study, we investigated the potential export of Mn-rich Antarctic shelf waters toward depleted open Southern Ocean waters. Our results showed that while high Mn concentrations were observed over the shelf, strong biological uptake decreased dissolved Mn concentrations in surface waters north of the Southern Antarctic Circumpolar Current Front (< 0.1 nM), limiting export of shelf Mn to the open Southern Ocean. Conversely, in bottom waters, mixing between Mn-rich Antarctic Bottom Waters and Mn-depleted Low Circumpolar Deep Waters combined with scavenging processes led to a decrease in dissolved Mn concentrations with distance from the coast. Subsurface dissolved Mn maxima represented a potential reservoir for surface waters (0.3 – 0.6 nM). However, these high subsurface values decreased with distance from the coast, suggesting these features may result from external sources near the shelf in addition to particle remineralization. Overall, these results imply that the lower-than-expected lateral export of trace metal-enriched waters contributes to the extremely low (< 0.1 nM) and potentially co-limiting Mn concentrations previously reported further north in this Southern Ocean region.

One of the most prominent plate tectonic processes is seafloor spreading. But its formation processes are poorly understood. In this study, we thoroughly address how the brittle-ductile weakening process affects the formation and development of tectonic patterns at spreading centers using 3D magmatic-thermomechanical numerical models. Grain size evolution and brittle/plastic strain weakening are fully coupled into the model. A spectrum of tectonic patterns, from asymmetric long-lived detachment faults in rolling-hinge mode, short-lived detachment faults in flip-flop mode, to symmetric conjugate faults in flip-flop mode are documented in our models. Systematic numerical results indicate that fault strength reduction and axial brittle layer thickness are two pivotal factors in controlling the faulting patterns and spreading modes. Strain weakening induced by localized hydrothermal alteration can lead to the variation of the fault strength reduction. Strong strain weakening with large fault strength reduction results in very asymmetric detachment faults developing in rolling-hinge mode, while weak strain weakening leads to small fault strength reduction, forming conjugate faults. Moreover, the thermal structure beneath the ridge is influenced by spreading rates, hydrothermal circulation, and mantle potential temperature, which in turn controls the thickness of the axial brittle layer and results in variation in tectonic patterns. Further, in order to test a damage mechanism with a physical basis, we investigate grain size reduction at the root of detachment faults. We found that its effect in the formation of detachment faults appears to play a subordinate role compared to brittle/plastic strain weakening of faults.

The Subpolar North Atlantic plays a critical role in the formation of the deep water masses which drive Atlantic Meridional Overturning Circulation (AMOC). Labrador Sea Water (LSW) is formed in the Labrador Sea and exported predominantly via the Deep Western Boundary Current (DWBC). The DWBC is an essential component of the AMOC advecting deep waters southward, flowing at depth along the continental slope of the western Atlantic. By combining sustained hydrographic observations from the Labrador Sea, Line W, Bermuda basin, and offshore of Abaco Island along 26.5°N, we investigate the signal propagation and advective timescales of LSW via the DWBC from its source region to the Tropical Atlantic through various approaches using robust neutral density classifications. Two individually-defined LSW classes are observed to advect on timescales that support a new plausible hydrographically-observed advective pathway. We find each LSW class to advect on independent timescales, and validate a hypothesized alternative-interior advection pathway branching from the DWBC by observing LSW outside of the DWBC in the Bermuda basin just prior to or on the same timescale as at 26.5°N- 10-15 years after leaving the source region. Advective timescales estimated herein indicate that this interior pathway is likely the main advective pathway; it remains uncertain whether a direct pathway plays a significant advective role. Using LSW convective signals as advective tracers along the DWBC permits the estimation of advective timescales from the subpolar to tropical latitudes, illuminating deep water advection pathways across the North Atlantic and the lower-limb of AMOC as a whole.

A document by Elsa Arellano-Torres. Click on the document to view its contents.

As tsunamis propagate across open oceans, they remain largely unseen due to the lack of adequate sensors, hence limiting the scope of existing tsunami warnings. A potential alternative method relies on the Global Navigation Satellites Systems to monitor the ionosphere for Traveling Ionospheric Disturbances created by tsunami-induced internal gravity waves (IGWs). The approach has been applied to tsunamis generated by earthquakes but rarely by undersea volcanic eruptions injecting energy into both the ocean and the atmosphere. The large 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption tsunami is thus a challenge for tsunami ionospheric imprint detection. Here, we show that in near-field regions (<1500km), despite the complex wavefield, we can isolate the tsunami imprint. We also highlight that the eruption-generated Lamb wave’s ionospheric imprints show an arrival time and an amplitude spatial pattern consistent with internal gravity wave origin.

Previous studies have identified intense climatic change in the Southern Ocean. However, the response of ACC transport to climate change is not fully understood. In this study, by using in-situ ocean bottom pressure (OBP) records and five GRACE products, long-term variations of ACC transport are studied. Our results confirm the reliability of GRACE CSR mascon product in ACC transport estimation at the Drake Passage. Superimposed on interannual variability, ACC transport exhibits an obvious increasing trend (1.32±0.07Sv year-1) during the GRACE era. Based on results of a mass-conservation ocean model simulation, we suggest that the acceleration of ACC is associated with intensified westerly winds and loss of land ice in Antarctica.