Cycle Of Ice Research Articles

Compensating Biases and a Noteworthy Success in the CMIP5 Representation of Antarctic Sea Ice Processes

AbstractCoupled Model Intercomparison Project phase 5 (CMIP5) climate models simulate a wide range of historical sea ice areas. Even models with areas close to observed values may contain compensating errors, affecting reliability of their projections. This study focuses on the seasonal cycle of sea ice, including analysis of model concentration budgets. Many models have insufficient autumn ice growth, leading to large winter biases. A subset of models accurately represent sea ice evolution year‐round. However, comparing their winter ice concentration budget to observations reveals a range of behaviors. At least one model has an accurate ice budget, which is only possible due to realistic ice drifts. The CMIP5 generation of model physics and resolution is therefore structurally capable of accurately representing processes in Antarctic sea ice. This implies that substantially improved projections of Antarctic dense ocean water formation and ice sheet melting are possible with appropriate subsetting of existing climate models.

Recent trends of ice phenology for eight large lakes using MODIS products in Northeast China

ABSTRACTOptical remote sensing images with high temporal resolution can be used to monitor lake ice phenology, a periodic freezing and thawing cycle of ice resulting from seasonal and inter-annual climate variations. In the research reported here, we used MODIS satellite data to establish the time series of lake ice extent and extracted lake ice phenology dates and durations for eight large typical lakes in Northeast China for the hydrological years from 2003 to 2016. The MODIS-derived results were validated against ice records at hydrological stations. The mean absolute error for a freeze-up start (FUS), freeze-up end (FUE), break-up start (BUS) and break-up end (BUE) was 3.1, 4.8, 6.6 and 6.6 days, respectively. Our findings indicated that the investigated lakes were tending to freeze later and melt earlier and were frozen for a shortened period over time. FUS was experiencing a delay of 0.65 days per year and BUE was advancing by 0.19 days per year, implying a decrease of frozen duration (FD) of 0.84 days per year taking all eight lakes into consideration. The lake ice duration increased with latitude, and the lakes with a relatively smaller area had a higher yearly rate of change and were more variable compared with the larger ones. The relationship between lake ice phenology and other influencing factors was evaluated using correlation coefficients and partial least squares regression. The results showed that the freeze-up process was more dependent on the lake morphometry, while the break-up process was more dependent on climate changes, particularly on air temperature, which had the highest correlation coefficient (r = −0.69, p < 0.01).

Dried, closed-path eddy covariance method for measuring carbon dioxide flux over sea ice

Abstract. The Arctic marine environment plays an important role in the global carbon cycle. However, there remain large uncertainties in how sea ice affects air–sea fluxes of carbon dioxide (CO2), partially due to disagreement between the two main methods (enclosure and eddy covariance) for measuring CO2 flux (FCO2). The enclosure method has appeared to produce more credible FCO2 than eddy covariance (EC), but is not suited for collecting long-term, ecosystem-scale flux datasets in such remote regions. Here we describe the design and performance of an EC system to measure FCO2 over landfast sea ice that addresses the shortcomings of previous EC systems. The system was installed on a 10 m tower on Qikirtaarjuk Island – a small rock outcrop in Dease Strait located roughly 35 km west of Cambridge Bay, Nunavut, in the Canadian Arctic Archipelago. The system incorporates recent developments in the field of air–sea gas exchange by measuring atmospheric CO2 using a closed-path infrared gas analyzer (IRGA) with a dried sample airstream, thus avoiding the known water vapor issues associated with using open-path IRGAs in low-flux environments. A description of the methods and the results from 4 months of continuous flux measurements from May through August 2017 are presented, highlighting the winter to summer transition from ice cover to open water. We show that the dried, closed-path EC system greatly reduces the magnitude of measured FCO2 compared to simultaneous open-path EC measurements, and for the first time reconciles EC and enclosure flux measurements over sea ice. This novel EC installation is capable of operating year-round on solar and wind power, and therefore promises to deliver new insights into the magnitude of CO2 fluxes and their driving processes through the annual sea ice cycle.

CALCULATION OF THE INFLUENCE OF THE COMPOSITION OF THE BIOGAS ON THE CHARACTERISTICS OF THE VEHICLE ENGINE

Decrease the consumption of mineral fuels in ICE is considered one of the important goals of reducing the harmful influence of this energy source on the environment. Within this plan, one of the most effective fuels type is biogas obtained from the processing of municipal solid waste and livestock waste. Biogas basically includes methane and carbon dioxide with a wide range of their ratio. The composition of biogas, in relation to the special features of obtaining it, can change, which leads to a change of indicators of the ICE. In connection with, the forecast of these indicators is actual, which is necessary for the development of effective systems for regulating the supply of biogas in the internal combustion engines. This forecast can be executed with the help of mathematical modeling of the working cycle of ICE with using adequate mathematical models. In this research used improved mathematical model of the working cycle of internal combustion engine developed in the department of piston power plant A. Podgorny Institute for Mechanical Engineering Problems NAS of Ukraine. The subject of the research is diesel engine D21A, converted to a gas engine, for which the investigations of possible options biogas composition were carried out with methane and carbon dioxide content in percentage terms: 100/0, 80/20, 60/40, 50/50, 40/60. Influence of the content in biogas of hydrogen, hydrogen sulfide, ammonia and nitrogen oxides in view of their smallness is neglected. The sufficiency of the mathematical model is verified by comparing the effective engine indicators obtained experimentally and by means of a calculation for the rated power mode of 18.5 kW (fuel-methane, n = 1800 min -1 , α = 1, φ = 25°, e = 9.5) . The difference in the comparison of the results didn't be less than 10 %, which proves the fidelity of the model. The influence of control actions on the parameters of an engine working on biogas is presented in the diagrams in X–Y coordinates. Graphical analysis of the results numerical experiment, depending on the changing parameter allows to predict the potential emission of NO, CO, CO 2 , economic indicators (g i , G i ), capacity indicator (p i ), the process quality index of the process inside the cylinder (η i ), to estimate the maximum values of temperature and pressure of the cycle as for the rated power mode (n = 1800 min -1 ) and for the maximum torque capacity (n = 1400 min -1 ), and retrieve additional info for different excess air ratio (α = 1.0, α = 1.1) by external velocity performance and load characteristics for all test parameters of the engine. A numerical experiment based on predict the characteristics of an engine running on biogas with a different ratio of CH 4 / CO 2 made it possible to make a quick, with sufficient accuracy, preliminary analysis indicator indexes of ICE with spark ignition. Inference should be drawn that the use of biogas as a motor fuel for stationary and transport power plants shows positive results, videlicet: improves index toxicity at a significant decrease in the economic index of the engine, decreases the thermal load on the parts of the cylinder-piston group, which contributes to the increase in their motor mileage allowance, the carbon dioxide balance in the environment is observed. The results of mathematical modeling can be useful in optimizing the working cycles of ICE, which are transferred to work with natural gas and biogas. They are also necessary in the development of such complex structures as automatic control systems for the supply of gaseous fuels in the internal combustion engine with the instability of its component composition and the resulting heat of combustion.

On the Seasonal Cycles Observed at the Continental Slope of the Eastern Eurasian Basin of the Arctic Ocean

AbstractThe Eurasian Basin (EB) of the Arctic Ocean is subject to substantial seasonality. We here use data collected between 2013 and 2015 from six moorings across the continental slope in the eastern EB and identify three domains, each with its own unique seasonal cycle: 1) The upper ocean (&lt;100 m), with seasonal temperature and salinity differences of Δθ = 0.16°C and ΔS = 0.17, is chiefly driven by the seasonal sea ice cycle. 2) The upper-slope domain is characterized by the influence of a hydrographic front that spans the water column around the ~750-m isobath. The domain features a strong temperature and moderate salinity seasonality (Δθ = 1.4°C; ΔS = 0.06), which is traceable down to ~600-m depth. Probable cause of this signal is a combination of along-slope advection of signals by the Arctic Circumpolar Boundary Current, local wind-driven upwelling, and a cross-slope shift of the front. 3) The lower-slope domain, located offshore of the front, with seasonality in temperature and salinity mainly confined to the halocline (Δθ = 0.83°C; ΔS = 0.11; ~100–200 m). This seasonal cycle can be explained by a vertical isopycnal displacement (ΔZ ~ 36 m), arguably as a baroclinic response to sea level changes. Available long-term oceanographic records indicate a recent amplification of the seasonal cycle within the halocline layer, possibly associated with the erosion of the halocline. This reduces the halocline’s ability to isolate the ocean surface layer and sea ice from the underlying Atlantic Water heat with direct implications for the evolution of Arctic sea ice cover and climate.

ICE Regimen for Relapsed/Refractory Bone and Soft Tissue Sarcomas in Children.

The outcome of bone and soft tissue sarcomas (BST) after relapse has very poor prognosis with survival rates less than 39%. Unfortunately there are not many treatment options, but promising responses have been reported with ifosfamide, etoposide and carboplatin (ICE). Therefore, we planned a study for children with recurrent/refractory BST treated with ICE regimen to evaluate their demographic features, responses to treatment and outcome. Patients with primary diagnosis of BST and treated with ICE regimen at the time of first or subsequent relapse, progression or unresponsive disease were selected for study. The files were retrospectively evaluated. Thirty of sixty-six patients had metastatic disease at relapse. Patients received median 5 cycles of ICE and were followed-up median 16.3 months. Overall survival rates were 83% and 62% at 1st and 2nd year. The ORR to the regimen was 43%. Survival rates were significantly higher in good responders (3-year EFS and OS rates: 50% vs. 8% and 78% vs. 14%; p<0.0001 and p<0.0001). Survival rates for non-metastatic disease were 42% and 75% for EFS and OS and higher than patients with metastases at relapse (p<0.001 and p<0.0001). EFS and OS rates of patients with rhabdomyosarcoma were 42% and 69%. No grade 3 or 4 renal toxicity was documented. ICE combination improves the outcome of relapsed or refractory sarcomas and it might serve as second line treatment. Patients with no metastases at relapse would benefit more than others with metastatic disease.

Water vapor deposition from the inner gas coma onto the nucleus of Comet 67P/Churyumov-Gerasimenko

Rosetta has detected water ice existing on the surface of Comet 67P/Churyumov-Gerasimenko in various types of features. One of particular interest is the frost-like layer observed at the edge of receding shadows during the whole mission, interpreted as the recondensation of a thin layer of water ice. Two possible mechanisms, (1) subsurface ice sublimation and (2) gas coma deposition, have been proposed for producing this recondensation process and diurnal cycles of water ice. Previous studies have demonstrated both mechanisms based on simplified models. More precise and modern models are yet insufficient when addressing the gas-coma-deposition mechanism. We aim to study the recondensation from the inner water gas coma of the 67P/Churyumov-Gerasimenko with more physical constraints including the OSIRIS images, nucleus shape model, and insolation conditions. We compute, for the first time, the backflux distributions from the coma with various boundary conditions. Numerical simulations of this gas-coma-deposition process show that the equivalent water ice deposition can be up to several microns in an hour of accumulation time close to the perihelion passage, which is comparable with the simulation results of the other subsurface-ice sublimation mechanism.

Arctic Sea Ice in a 1.5°C Warmer World

AbstractWe examine the seasonal cycle of Arctic sea ice in scenarios with limited future global warming. To do so, we analyze two sets of observational records that cover the observational uncertainty of Arctic sea ice loss per degree of global warming. The observations are combined with 100 simulations of historical and future climate evolution from the Max Planck Institute Earth System Model Grand Ensemble. Based on the high‐sensitivity observations, we find that Arctic September sea ice is lost with low probability (P≈ 10%) for global warming of +1.5°C above preindustrial levels and with very high probability (P&gt; 99%) for global warming of +2°C above preindustrial levels. For the low‐sensitivity observations, September sea ice is extremely unlikely to disappear for +1.5°C warming (P≪ 1%) and has low likelihood (P≈ 10%) to disappear even for +2°C global warming. For March, both observational records suggest a loss of 15% to 20% of Arctic sea ice area for 1.5°C to 2°C global warming.

Excellent treatment outcomes in children younger than 18 months with stage 4 MYCN nonamplified neuroblastoma.

PurposeAlthough the prognosis is generally good in patients with intermediate-risk neuroblastoma, no consensus has been reached on the ideal treatment regimen. This study analyzed treatment outcomes and toxicities in patients younger than 18 months with stage 4 MYCN nonamplified neuroblastoma.MethodsWe retrospectively analyzed 20 patients younger than 18 months newly diagnosed with stage 4 MYCN nonamplified neuroblastoma between January 2009 and December 2015. Patients received 9 cycles of chemotherapy and surgery, with or without local radiotherapy, followed by 12 cycles of differentiation therapy with 13-cis-retinoic acid. Chemotherapy consisted of alternating cycles of cisplatin, etoposide, doxorubicin, and cyclophosphamide (CEDC) and ifosfamide, carboplatin, and etoposide (ICE) regimens.ResultsThe most common primary tumor site was the abdomen (85%), and the most common metastatic sites were the lymph nodes (65%), followed by the bones (60%), liver (55%), skin (45%), and bone marrow (25%). At the end of induction therapy, 14 patients (70%) achieved complete response, with 1 achieving very good partial response, 4 achieving partial response, and 1 showing mixed response. Nine patients (45%) received local radiotherapy. At a median follow-up of 47 months (range, 17–91 months), none of these patients experienced relapse, progression, or secondary malignancy, or died. Three years after chemotherapy completion, none of the patients had experienced grade ≥3 late adverse effects.ConclusionPatients younger than 18 months with stage 4 MYCN nonamplified neuroblastoma showed excellent outcomes, without significant late adverse effects, when treated with alternating cycles of CEDC and ICE, followed by surgery and differentiation therapy.

Simulations of Eurasian winter temperature trends in coupled and uncoupled CFSv2

Conflicting results have been presented regarding the link between Arctic sea-ice loss and midlatitude cooling, particularly over Eurasia. This study analyzes uncoupled (atmosphere-only) and coupled (ocean–atmosphere) simulations by the Climate Forecast System, version 2 (CFSv2), to examine this linkage during the Northern Hemisphere winter, focusing on the simulation of the observed surface cooling trend over Eurasia during the last three decades. The uncoupled simulations are Atmospheric Model Intercomparison Project (AMIP) runs forced with mean seasonal cycles of sea surface temperature (SST) and sea ice, using combinations of SST and sea ice from different time periods to assess the role that each plays individually, and to assess the role of atmospheric internal variability. Coupled runs are used to further investigate the role of internal variability via the analysis of initialized predictions and the evolution of the forecast with lead time. The AMIP simulations show a mean warming response over Eurasia due to SST changes, but little response to changes in sea ice. Individual runs simulate cooler periods over Eurasia, and this is shown to be concurrent with a stronger Siberian high and warming over Greenland. No substantial differences in the variability of Eurasian surface temperatures are found between the different model configurations. In the coupled runs, the region of significant warming over Eurasia is small at short leads, but increases at longer leads. It is concluded that, although the models have some capability in highlighting the temperature variability over Eurasia, the observed cooling may still be a consequence of internal variability.

Mid-Pleistocene climate transition: Characteristic, mechanism and perspective

Milankovich theory suggested that orbitally induced summer insolation change at high-latitude region of Northern Hemisphere played a key role in driving the ice cycles during the Pleistocene. However, a significant shift of the Pleistocence climate from 41-ka to 100-ka cycles (namely mid-Pleistocene transition, MPT) cannot be simply attributed to the astronomical forcing due to insignificant insolation change induced by eccentricity forcing. Here we summarized multiple proxies generated from the ocean and land to address Pleistocene climate changes such as global ice volume, sea surface temperature, sea level, aridity of dust sources, and monsoon-related hydrological cycles. The temporal and spatial characteristics of the MPT phenomenon, in terms of the timing, duration, amplitudes and frequencies, were addressed using spectral and wavelet results. Most records reveal that the MPT was commenced as the onset of the ~100-ka cycles at ~1.2 Ma, and ended by the establishment of the dominant 100-ka cycles at ~0.7 Ma. However, some hydroclimatic proxies from the Mediterranean Sea, South China Sea and Chinese caves show a relatively strong 23-ka cycles during the middle to late Pleistocence. Such a difference may be attributable to varied sensitivity of proxy indicators to the insolation and glacial forcing. Globally, temperature and sea level signals that are affected by changing ice volume usually demonstrate a distinctive and consistent MPT. By contrast, regional hydroclimatic proxies at mid-to-low latitudes are likely dominated by the precession cycles (i.e. high-resolution, absolutely dated Chinese speleothem records). The MPT associated with the onset of ~100-ka cycles has inspired the paleocommunities to address its driving mechanism from both data and model perspectives. Several hypotheses have been proposed to explain the MPT in the past two decades, including nonlinear response to external forcing and complicated internal feedbacks. The nonlinear response to the astronomical forcing including eccentricity (100-ka cycle), interplay between obliquity (41-ka cycle) and precession (23- and 19-ka cycles) can produce the 100-ka ice-age cycles. However, model results suggest that the MPT and subsequent ″100 ka world″ are likely caused by changes in atmospheric CO2 concentration, bedrock exposure or ocean circulations. Taking these different hypotheses together, it was suggested that the solar insolation caused by changing Earth′s orbital parameters as external forcing, drives the glacial-interglacial climate cycles, whilst the nonlinear responses to atmospheric CO2 decrease and to different regolith boundary conditions as internal feedbacks have played key roles in triggering the climate transition and amplifying the glacial-interglacial oscillations. While most proxies from the land and ocean demonstrate a remarkable MPT from 41- to 100-ka cycles, regional high-resolution proxy records indicated that hydroclimatic changes at mid-to-low latitudes exhibit insignificant MPT and weak ~100-ka cycles after the MPT. In the future, more data assimilation should be focused on the hydroclimatic changes particularly in monsoon-affected regions to decipher the diverse responses in a regional scale. Meanwhile, simulations using high-resolution regional climate system models should be performed to quantify the responses of different climate parameters to external forcing and internal feedback. Through intensively data-model comparison, new insights into past climate variability and dynamics will permit a better projection of future climate change under the global warming context.

An Autonomous Approach to Observing the Seasonal Ice Zone in the Western Arctic

The Marginal Ice Zone and Arctic Sea State programs examined the processes that govern evolution of the rapidly changing seasonal ice zone in the Beaufort Sea. Autonomous platforms operating from the ice and within the water column collected measurements across the atmosphere-ice-ocean system and provided the persistence to sample continuously through the springtime retreat and autumn advance of sea ice. Autonomous platforms also allowed operational modalities that reduced the field programs’ logistical requirements. Observations indicate that thermodynamics, especially the radiative balances of the ice-albedo feedback, govern the seasonal cycle of sea ice, with the role of surface waves confined to specific events. Continuous sampling from winter into autumn also reveals the imprint of winter ice conditions and fracturing on summertime floe size distribution. These programs demonstrate effective use of integrated systems of autonomous platforms for persistent, multiscale Arctic observing. Networks of autonomous systems are well suited to capturing the vast scales of variability inherent in the Arctic system.

Remote Sensing of Oil In and Under Ice in a Climate-Controlled Test Basin

Abstract (2017-111) The ability to rapidly detect and delineate an oil spill in an Arctic environment is critical for efficient and effective response. The International Association of Oil and Gas Producers (IOSP), Arctic Oil Spill Response Technology – Joint Industry Programme (JIP) funded a novel controlled laboratory experiment to assess the relative efficacy of a variety of remote sensing instruments. This unbiased evaluation of existing and emerging technologies was recently conducted in the Ice Engineering Test Basin at the U.S. Army Engineer Research and Development Center’s Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire, USA. CRREL provided the unique testing environment for sensor evaluation using the 120 ft. long by 30 ft. wide by 8 ft. deep Test Basin. The refrigerated Test Basin was filled with a manufactured saltwater solution and an 80 cm sea ice sheet was grown with fifteen individual containment hoops. Within the individual containment hoops, oil volumes were injected at predetermined ice thicknesses leading to oil encapsulation at differing ice depths. The Prince William Sound Oil Spill Recovery Institute assembled a team of remote sensing experts to select, operate and interpret sensors to examine and validate oil detection capabilities in level sea ice. Testing covered the full ice cycle from fresh oil and encapsulated oil in growing ice to migrating oil during ice melt out. Five aerial sensors were attached to a cantilevered boom on a motorized carriage operating above the ice surface, while at the bottom of the tank were nine subsea sensors installed on a computer-controlled traveling underwater platform Ice cores were obtained outside the hoops during ice growth and in designated hoops during the melt-out phase, with the objective of characterizing ice structure and oil migration using crystallography and CT scanning. Environmental measurements that would affect sensor performance such as resistivity, acoustics, air, ice and water temperatures were also recorded. This experiment provided a comprehensive side-by comparison of the sensors evaluated, while correlating measurements with the ice properties. The paper will provide a full description of the hoop layout plan, the oil injection process, and the measurements schedule that minimized sensor interference.

Japan Meteorological Agency/Meteorological Research Institute-Coupled Prediction System version 2 (JMA/MRI-CPS2): atmosphere–land–ocean–sea ice coupled prediction system for operational seasonal forecasting

This paper describes the Japan Meteorological Agency/Meteorological Research Institute-Coupled Prediction System version 2 (JMA/MRI-CPS2), which was put into operation in June 2015 for the purpose of performing seasonal predictions. JMA/MRI-CPS2 has various upgrades from its predecessor, JMA/MRI-CPS1, including improved resolution and physics in its atmospheric and oceanic components, introduction of an interactive sea-ice model and realistic initialization of its land component. Verification of extensive re-forecasts covering a 30-year period (1981–2010) demonstrates that JMA/MRI-CPS2 possesses improved seasonal predictive skills for both atmospheric and oceanic interannual variability as well as key coupled variability such as the El Nino–Southern Oscillation (ENSO). For ENSO prediction, the new system better represents the forecast uncertainty and transition/duration of ENSO phases. Our analysis suggests that the enhanced predictive skills are attributable to incremental improvements resulting from all of the changes, as is apparent in the beneficial effects of sea-ice coupling and land initialization on 2-m temperature predictions. JMA/MRI-CPS2 is capable of reasonably representing the seasonal cycle and secular trends of sea ice. The sea-ice coupling remarkably enhances the predictive capability for the Arctic 2-m temperature, indicating the importance of this factor, particularly for seasonal predictions in the Arctic region.

Effects of microstructure design on aluminum surface hydrophobic and ice‐retarding properties

AbstractThe poor mechanical strength of superhydrophobic surface limits its use in civil aviation. In this work, superhydrophobic surfaces with open and closed microstructure design were prepared, and their hydrophobicity and icephobicity over icing/de‐icing cycles were thoroughly studied. For all samples, contact angle decreased and contact angle hysteresis increased over time. However, surface with interconnected hollow honeycomb microstructure design kept its Cassie–Baxter state even after 20 times icing/de‐icing cycles, while surface with repeated individual post microscopic unit lost its superhydrophobicity only after six times icing/de‐icing cycles. The interconnected hollow honeycomb microstructure design strengthened surface mechanical strength by lowering the damage to microscopic unit. The freezing time for water droplet on surface with interconnected hollow honeycomb microstructure design was only slightly shortened over time. The difference in water/ice‐solid contact area for surfaces with different nano‐microscale design also led to the difference in wetting and ice‐retarding ability. Surface with interconnected hollow honeycomb microstructure design showed the strongest ice‐retarding ability followed by surface with interconnected hollow brick, ladder type, and triangle shape microstructure design. © 2017 Curtin University of Technology and John Wiley &amp; Sons, Ltd.

Sea ice cycle in western Hudson Bay, Canada, from a polar bear perspective

Sea ice cycle in western Hudson Bay, Canada, from a polar bear perspective

Length of large leads in drifting ice of the sub-Atlantic part of the Arctic Basin with the use of satellite images

Data on the extent of the large discontinuities of drifting ice in the Western part of the Arctic basin are ana‑ lyzed for the period from October 2005 to September 2012. The data were obtained as a result of decoding the low resolution images received from the NOAA satellites. Areas with the low, medium and high lengths of the leads were isolated. It was found that, during the entire ice cycle, areas with low lengths (less than 100 km) were the most numerous. Definite seasonal as well as inter‑annual variations were also determined in the changes of repeatability of the lead lengths in the ice cover, its relative value and the average values. They are manifested in changes of the mentioned parameters being calculated for both, the whole set of leads, and separately from data within each of the isolated areas. The seasonal variations of these parameters are shown to be consistent with the well‑known intra‑annual changes in the state of drifting ice, consisting in the development of the process of ice formation from October to March, and the subsequent destruction of the ice fields in April–June. Fluctuations with duration up to five years were revealed within the inter‑annual changes of characteristics of the lengths of leads. The presence of these inter‑annual changes may be explained by the development of the processes leading to «weakening» of drifting ice during the period under consideration. The assumption that the fluctuations in the length of discontinuities of the ice were related to the changes of the rate of the ice drift is grounded.

A post-new horizons global climate model of Pluto including the N2, CH4 and CO cycles

We have built a new 3D Global Climate Model (GCM) to simulate Pluto as observed by New Horizons in 2015. All key processes are parametrized on the basis of theoretical equations, including atmospheric dynamics and transport, turbulence, radiative transfer, molecular conduction, as well as phases changes for N2, CH2 and CO. Pluto’s climate and ice cycles are found to be very sensitive to model parameters and initial states. Nevertheless, a reference simulation is designed by running a fast, reduced version of the GCM with simplified atmospheric transport for 40,000 Earth years to initialize the surface ice distribution and sub-surface temperatures, from which a 28-Earth-year full GCM simulation is performed. Assuming a topographic depression in a Sputnik-planum (SP)-like crater on the anti-Charon hemisphere, a realistic Pluto is obtained, with most N2 and CO ices accumulated in the crater, methane frost covering both hemispheres except for the equatorial regions, and a surface pressure near 1.1 Pa in 2015 with an increase between 1988 and 2015, as reported from stellar occultations. Temperature profiles are in qualitative agreement with the observations. In particular, a cold atmospheric layer is obtained in the lowest kilometers above Sputnik Planum, as observed by New Horizons’s REX experiment. It is shown to result from the combined effect of the topographic depression and N2 daytime sublimation. In the reference simulation with surface N2 ice exclusively present in Sputnik Planum, the global circulation is only forced by radiative heating gradients and remains relatively weak. Surface winds are locally induced by topography slopes and by N2 condensation and sublimation around Sputnik Planum. However, the circulation can be more intense depending on the exact distribution of surface N2 frost. This is illustrated in an alternative simulation with N2 condensing in the South Polar regions and N2 frost covering latitudes between 35°N and 48°N. A global condensation flow is then created, inducing strong surface winds everywhere, a prograde jet in the southern high latitudes, and an equatorial superrotation likely forced by barotropic instabilities in the southern jet. Using realistic parameters, the GCM predict atmospheric concentrations of CO and CH4 in good agreement with the observations. N2 and CO do not condense in the atmosphere, but CH4 ice clouds can form during daytime at low altitude near the regions covered by N2 ice (assuming that nucleation is efficient enough). This global climate model can be used to study many aspects of the Pluto environment. For instance, organic hazes are included in the GCM and analysed in a companion paper (Bertrand and Forget, Icarus, this issue).

Safety and Activity of Brentuximab Vedotin (BV) Plus Ifosfamide, Carboplatin, and Etoposide (ICE) for Relapsed/Refractory (Rel/Ref) Classical Hodgkin Lymphoma (cHL): Initial Results of a Phase I/II Trial

Background: When initial therapy for cHL fails, the standard approach is multiagent salvage chemotherapy followed by autologous stem cell transplant (ASCT). The success of ASCT can be predicted by achievement of complete remission (CR) by fluorodeoxyglucose positron emission tomography (PET) following salvage chemotherapy (Moskowitz, et al. Blood 2012;119:1665-70). Unfortunately, about half of patients (pts) are unable to achieve CR with first salvage. The anti-CD30 antibody-drug conjugate BV is effective as a single agent in rel/ref cHL (Younes, et al. JCO 2012;30:2183-9). Pre-ASCT salvage chemotherapy combinations with BV have been explored (LaCasce, et al. ASH 2015, #293; Garcia-Sanz, et al. ASH 2015, #582), as has a PET-adapted sequential approach with BV then ICE (Moskowitz, et al. Lancet Oncol 2015;16:284-92). We hypothesized that concurrent therapy with BV and ICE would be safe and produce high CR rates. We also sought to explore inflammatory microenvironment prognostic factors. (ClinicalTrials.gov #NCT02227199)Methods: Pts ≥ 18 years old with first relapse or primary refractory CD30+ cHL were eligible. Key inclusion criteria were ≥ 1 FDG-avid site of disease ≥ 1 cm; adequate marrow, hepatic, and renal function; and HIV-. Key exclusions were any prior BV; chemotherapy ≤ 3 weeks of enrollment; and pre-existing neuropathy > NCI-CTCAE Grade 1. All pts signed IRB-approved informed consent forms. Treatment included BV on Days 1 and 8, ifosfamide and mesna 5 g/m2 each on Day 2, carboplatin AUC 5 (capped at 800 mg) on Day 2, and etoposide 100 mg/m2daily on Days 1-3. A 3+3 dose-escalation schema for BV was used to determine the maximum tolerated dose (MTD) with ICE: starting dose was 1.2 mg/kg on Days 1 and 8, escalated to 1.5 mg/kg on Days 1 and 8 or de-escalated to 1.2 mg/kg on Day 1 only, based on rate of dose-limiting toxicity (DLT). Once MTD of BV was established, subsequent pts received this dose. 2 21-day cycles were given with G-CSF support. PET was performed after Cycle 2, with response assigned per Cheson 2007. Stem cells were collected after Cycle 2 at discretion of treating investigator. Peripheral blood (PB) pre- and post-treatment, stem cell (PBSC) product, and (when available) archived formalin-fixed paraffin-embedded tissue from presentation and relapse were collected for correlative studies. Pre-treatment PB PD-L1 levels were measured by ELISA.Results: To date, 16 pts have enrolled and completed study treatment. Median age was 32 (range, 23-60). All received ABVD-based initial chemotherapy, and 5 (31%) received radiation. 11 (69%) did not obtain CR with initial therapy. Grade 3-4 neutropenia, lymphopenia, and anemia was seen in 2 (12%) pts each; thrombocytopenia in 4 (25%) pts. 6 (38%) pts experienced Grade 3-4 non-heme toxicity, but no single toxicity occurred in > 1 pt. Neuropathy was seen in 5 (31%) pts: 4 Grade 1, and 1 Grade 3. 1 DLT (sepsis) was observed in the 9 pts treated in the dose-escalation phase, defining 1.5 mg/kg on Days 1 and 8 as the MTD of BV with ICE.Overall response rate for all enrolled patients was 94% (n=14), with 88% (n=14) and 69% (n=11) achieving CR by investigator and central independent radiographic review, respectively. 15 (94%) pts underwent PBSC collection, all of which were successful. 12 (75%) pts proceeded to ASCT immediately following this treatment. With a median follow-up of 6.5 (range, 2-20) months, there have been 3 (19%) relapses (2 were in CR after BV-ICE) and no deaths.Counts of CD68+ macrophages (15%, 14%), granzyme+ cytotoxic cells (6.2%, 8.7%), and CD20+ B cells (24%, 14%) by immunohistochemistry were not significantly different between presentation and relapse (respectively). Levels of PD-L1 were below the limit of detection (500 pg/mL) in all pts.Conclusions: Pts with rel/ref cHL can safely receive BV up to 1.5mg/kg on Days 1 and 8 per cycle of ICE. Apart from generally-mild neuropathy, adding BV does not appreciably change the toxicity profile of ICE. Observed response rates by PET are very encouraging. Inflammatory cell composition appears similar at presentation and relapse. Without more sensitive testing, circulating levels of PD-L1 are unlikely to be of use in this setting. Enrollment is ongoing, and updated clinical and correlative data, including the use of next-generation sequencing-based detection of lymphoma-specific DNA sequence as a novel method of response assessment, will be presented at the meeting. DisclosuresGopal:Seattle Genetics: Research Funding.

Teleconnections in STEAM: Antarctic Field-Camp Art

We describe a component of a multi-element STEAM collaboration looking to explore ideas around the life cycle of Antarctic sea ice. One of the intermediate phases of the work involved the scientist deploying partially pre-made art components. Results were modulated by weather and operational constraints and generated a sequence of images and recordings as well as greater understanding of the creative collaboration process.