ウィスコンシン ダイガク マディソンコウ ガ ジッシ シテイル ナンキョク ムジン キショウ カンソク (AWS) ケイカク ノ 2011-2012 ネン カキ ノ カツドウ

ウィスコンシン大学マディソン校で推進している南極無人気象観測計画(Antarctic Automatic Weather Station(AWS)program)の32 年目の観測が,2011/2012年の南半球夏期に完了した.無人気象観測網を利用して南極の気象と気候の研究が行われている.今シーズンはロス島周辺域,ロス棚氷,西南極,東南極にわたる領域で活動した.基本的に観測点のデータはアルゴス衛星を中継して配信されるが,今年はロス島周辺域の多くの観測点で,マクマード基地を中継して"Freewave modem"を通して配信された.各無人気象観測点報告には,現在設置されている測器と動作状況が含まれる.また,無人気象観測計画の全体像を,野外活動の実施状況に沿って示す.During the 2011-2012 austral summer, the Antarctic Automatic Weather Station (AWS) program at the University of Wisconsin?Madison completed its 32nd year of observations. Ongoing studies utilizing the network include topics in Antarctic meteorology and climate studies. This field season consisted of work throughout the Ross Island area, the Ross Ice Shelf, West Antarctica, and East Antarctica. Argos satellite transmissions are the primary method for relaying station data, but throughout this year, a number of stations in the Ross Island area have been converted to Freewave modems, with their data being relayed through McMurdo station. Each AWS station report contains information regarding the instrumentation currently installed and the work performed at each site. An overview of the AWS applications is included along with field work accomplished

Land Surface Climate in the Regional Arctic System Model

The article of record as published may be found at http://dx.doi.org/10.1175/JCLI-D-15-0415.1The Regional Arctic System Model (RASM) is a fully coupled, regional Earth system model applied over the pan-Arctic domain. This paper discusses the implementation of the Variable Infiltration Capacity land surface model (VIC) in RASM and evaluates the ability of RASM, version 1.0, to capture key features of the land surface climate and hydrologic cycle for the period 1979-2014 in comparison with uncoupled VIC simulations, reanalysis datasets, satellite measurements, and in situ observations. RASM reproduces the dominant features of the land surface climatology in the Arctic, such as the amount and regional distribution of precipitation, the partitioning of precipitation between runoff and evapotranspiration, the effects of snow on the water and energy balance, and the differences in turbulent fluxes between the tundra and taiga biomes. Surface air temperature biases in RASM, compared to reanalysis datasets ERA-Interim and MERRA, are generally less than 2 degrees C; however, in the cold seasons there are local biases that exceed 6 degrees C. Compared to satellite observations, RASM captures the annual cycle of snow-covered area well, although melt progresses about two weeks faster than observations in the late spring at high latitudes. With respect to derived fluxes, such as latent heat or runoff, RASM is shown to have similar performance statistics as ERA-Interim while differing substantially from MERRA, which consistently overestimates the evaporative flux across the Arctic region.U.S. Department of Energy (DOE) [DE-FG02-07ER64460, DE-SC0006856, DE-SC0006178]; DO

Going with the floe: tracking CESM Large Ensemble sea ice in the Arctic provides context for ship-based observations

In recent decades, Arctic sea ice has shifted toward a younger, thinner, seasonal ice regime. Studying and understanding this &ldquo;new&rdquo; Arctic will be the focus of a year-long ship campaign beginning in autumn 2019. Lagrangian tracking of sea ice floes in the Community Earth System Model Large Ensemble (CESM-LE) during representative &ldquo;perennial&rdquo; and &ldquo;seasonal&rdquo; time periods allows for understanding of the conditions that a floe could experience throughout the calendar year. These model tracks, put into context a single year of observations, provide guidance on how observations can optimally shape model development, and how climate models could be used in future campaign planning. The modeled floe tracks show a range of possible trajectories, though a Transpolar Drift trajectory is most likely. There is also a small but emerging possibility of high-risk tracks, including possible melt of the floe before the end of a calendar year. We find that a Lagrangian approach is essential in order to correctly compare the seasonal cycle of sea ice conditions between point-based observations and a model. Because of high variability in the melt season sea ice conditions, we recommend in situ sampling over a large range of ice conditions for a more complete understanding of how ice type and surface conditions affect the observed processes. We find that sea ice predictability emerges rapidly during the autumn freeze-up and anticipate that process-based observations during this period may help elucidate the processes leading to this change in predictability. </div

Antarctic atmospheric boundary layer observations with the Small Unmanned Meteorological Observer (SUMO)

Between&nbsp;January&nbsp;2012 and June&nbsp;2017 a small unmanned aerial system (sUAS), known as the Small Unmanned Meteorological Observer (SUMO), was used to observe the state of the atmospheric boundary layer in the Antarctic. During six Antarctic field campaigns, 116 SUMO flights were completed. These flights took place during all seasons over both permanent ice and ice-free locations on the Antarctic continent and over sea ice in the western Ross Sea. Sampling was completed during spiral ascent and descent flight paths that observed the temperature, humidity, pressure and wind up to 1000&thinsp;m above ground level and sampled the entire depth of the atmospheric boundary layer, as well as portions of the free atmosphere above the boundary layer. A wide variety of boundary layer states were observed, including very shallow, strongly stable conditions during the Antarctic winter and deep, convective conditions over ice-free locations in the summer. The Antarctic atmospheric boundary layer data collected by the SUMO sUAS, described in this paper, can be retrieved from the United States Antarctic Program Data Center (https://www.usap-dc.org, last access: 8&nbsp;March&nbsp;2021). The data for all flights conducted on the continent are available at https://doi.org/10.15784/601054 (Cassano, 2017), and data from the Ross Sea flights are available at https://doi.org/10.15784/601191 (Cassano, 2019). </div

Optimisation de laboratoires médicaux

This thesis focuses on the optimization of clinical laboratory design and operating decisions. A clinicallaboratory is an organization gathering human and machinery resources to analyze blood samples. Inthis thesis, a decision support tool including mathematical models, a heuristic algorithm and acustomized simulation model is developed to aid decision makers for the main strategic, tactical andoperational problems in clinical laboratory design and operations management. This decision supporttool follows a top-down stepwise framework starting from strategic problems and ending withoperational ones, including a recursive loop for modification and improvement. In this thesis, machineselection and facility layout are studied as the main strategic problems, analyzer configuration problemas the tactical problem, and assignment, aliquoting, and scheduling as the principal operationalproblems. In order to deal with machine selection problem for clinical laboratory, a mathematical modelis proposed which aids to select the most appropriate machines to equip the system. To tackle physicalarrangement of instruments within the laboratory area, a heuristic approach is developed. The proposedheuristic comprises the key constraints of laboratory layout design. To address the analyzerconfiguration problem which mainly deals with the assignment of chemical materials to the analyzersin clinical laboratory, a bi-objective mathematical model is developed. In addition, to determine anefficient assignment of sample tubes to the analyzers, a mathematical model with three objectives isproposed. A customized, flexible, and fine-grained simulation model is developed in FlexSim to studythe clinical laboratory designed through the outputs of developed mathematical models and layoutalgorithm. Simulation model plays a key role in the proposed framework as it is used for many purposes.The simulation model helps the designer to construct and analyze a complete clinical laboratory takinginto account all major features of the system. This simulation attribute provides the ability to scrutinizethe system behaviour and to find out whether the designed system is efficient. System performanceanalysis through simulation and resulting key performance indicators give helpful feedbacks for systemimprovement. Furthermore, simulation model can be fruitful to decide on scheduling, aliquoting andstaffing problems through the evaluation of various scenarios proposed by decision maker for each ofthese problems. To verify the validity of the proposed framework, data extracted from a real case isused. The output results seal on the applicability and the efficiency of the proposed framework as wellas competency of proposed techniques to deal with each optimization problem. To the best of ourknowledge, this thesis is one of the leading studies on the optimization of clinical laboratories.Cette thèse porte sur l'optimisation de la conception et des décisions opérationnelles des laboratoires d'analyses médicales. Dans cette thèse, un outil d'aide à la décision comprenant des modèles mathématiques, un algorithme heuristique et un modèle de simulation personnalisé est développé pour aider les décideurs à résoudre les principaux problèmes stratégiques, tactiques et opérationnels en conception et gestion des opérations des laboratoires d'analyses médicales. Dans cette thèse, la sélection des machines et la disposition des instruments sont étudiées en tant que principaux problèmes stratégiques, le problème de configuration des analyseurs en tant que problème tactique et l’affectation, l’aliquotage et l'ordonnancement en tant que principaux problèmes opérationnels. Un modèle de simulation personnalisé et flexible est développé dans FlexSim pour étudier le laboratoire d'analyse médicale conçu à l'aide des résultats de modèles mathématiques et d'un algorithme de layout développés. Le modèle de simulation aide le concepteur à construire et à analyser un laboratoire complet en tenant compte de toutes les principales caractéristiques du système. Cet attribut de simulation permet d'analyser le comportement du système et de déterminer si le système conçu est efficace. Pour vérifier la validité du cadre proposé, les données extraites d’un cas réel sont utilisées. Les résultats de sortie scellent l'applicabilité et l'efficacité du cadre proposé ainsi que la compétence des techniques proposées pour traiter chaque problème d'optimisation. À notre connaissance, cette thèse est l’une des principales études sur l’optimisation des laboratoires d'analyses médicales

A New Ocean State After Nuclear War

Nuclear war would produce dire global consequences for humans and our environment. We simulated climate impacts of US-Russia and India-Pakistan nuclear wars in an Earth System Model, here, we report on the ocean impacts. Like volcanic eruptions and large forest fires, firestorms from nuclear war would transport light-blocking aerosols to the stratosphere, resulting in global cooling. The ocean responds over two timescales: a rapid cooling event and a long recovery, indicating a hysteresis response of the ocean to global cooling. Surface cooling drives sea ice expansion, enhanced meridional overturning, and intensified ocean vertical mixing that is expanded, deeper, and longer lasting. Phytoplankton production and community structure are highly modified by perturbations to light, temperature, and nutrients, resulting in initial decimation of production, especially at high latitudes. A new physical and biogeochemical ocean state results, characterized by shallower pycnoclines, thermoclines, and nutriclines, ventilated deep water masses, and thicker Arctic sea ice. Persistent changes in nutrient limitation drive a shift in phytoplankton community structure, resulting in increased diatom populations, which in turn increase iron scavenging and iron limitation, especially at high latitudes. In the largest US-Russia scenario (150 Tg), ocean recovery is likely on the order of decades at the surface and hundreds of years at depth, while changes to Arctic sea-ice will likely last thousands of years, effectively a “Nuclear Little Ice Age.” Marine ecosystems would be highly disrupted by both the initial perturbation and in the new ocean state, resulting in long-term, global impacts to ecosystem services such as fisheries.publishedVersio

Evaluation of the atmosphere–land–ocean–sea ice interface processes in the Regional Arctic System Model version 1 (RASM1) using local and globally gridded observations

The Regional Arctic System Model version 1 (RASM1) has been developed to provide high-resolution simulations of the Arctic atmosphere–ocean–sea ice–land system. Here, we provide a baseline for the capability of RASM to simulate interface processes by comparing retrospective simulations from RASM1 for 1990–2014 with the Community Earth System Model version 1 (CESM1) and the spread across three recent reanalyses. Evaluations of surface and 2 m air temperature, surface radiative and turbulent fluxes, precipitation, and snow depth in the various models and reanalyses are performed using global and regional datasets and a variety of in situ datasets, including flux towers over land, ship cruises over oceans, and a field experiment over sea ice. These evaluations reveal that RASM1 simulates precipitation that is similar to CESM1, reanalyses, and satellite gauge combined precipitation datasets over all river basins within the RASM domain. Snow depth in RASM is closer to upscaled surface observations over a flatter region than in more mountainous terrain in Alaska. The sea ice–atmosphere interface is well simulated in regards to radiation fluxes, which generally fall within observational uncertainty. RASM1 monthly mean surface temperature and radiation biases are shown to be due to biases in the simulated mean diurnal cycle. At some locations, a minimal monthly mean bias is shown to be due to the compensation of roughly equal but opposite biases between daytime and nighttime, whereas this is not the case at locations where the monthly mean bias is higher in magnitude. These biases are derived from errors in the diurnal cycle of the energy balance (radiative and turbulent flux) components. Therefore, the key to advancing the simulation of SAT and the surface energy budget would be to improve the representation of the diurnal cycle of radiative and turbulent fluxes. The development of RASM2 aims to address these biases. Still, an advantage of RASM1 is that it captures the interannual and interdecadal variability in the climate of the Arctic region, which global models like CESM cannot do

First description of in situ chlorophyll fluorescence signal within East Antarctic coastal polynyas during fall and winter

Antarctic coastal polynyas are persistent and recurrent regions of open water located between the coast and the drifting pack-ice. In spring, they are the first polar areas to be exposed to light, leading to the development of phytoplankton blooms, making polynyas potential ecological hotspots in sea-ice regions. Knowledge on polynya oceanography and ecology during winter is limited due to their inaccessibility. This study describes i) the first in situ chlorophyll fluorescence signal (a proxy for chlorophyll-a concentration and thus presence of phytoplankton) in polynyas between the end of summer and winter, ii) assesses whether the signal persists through time and iii) identifies its main oceanographic drivers. The dataset comprises 698 profiles of fluorescence, temperature and salinity recorded by southern elephant seals in 2011, 2019-2021 in the Cape-Darnley (CDP;67˚S-69˚E) and Shackleton (SP;66˚S-95˚E) polynyas between February and September. A significant fluorescence signal was observed until April in both polynyas. An additional signal occurring at 130m depth in August within CDP may result from in situ growth of phytoplankton due to potential adaptation to low irradiance or remnant chlorophyll-a that was advected into the polynya. The decrease and deepening of the fluorescence signal from February to August was accompanied by the deepening of the mixed layer depth and a cooling and salinification of the water column in both polynyas. Using Principal Component Analysis as an exploratory tool, we highlighted previously unsuspected drivers of the fluorescence signal within polynyas. CDP shows clear differences in biological and environmental conditions depending on topographic features with higher fluorescence in warmer and saltier waters on the shelf compared with the continental slope. In SP, near the ice-shelf, a significant fluorescence signal in April below the mixed layer (around 130m depth), was associated with fresher and warmer waters. We hypothesize that this signal could result from potential ice-shelf melting from warm water intrusions onto the shelf leading to iron supply necessary to fuel phytoplankton growth. This study supports that Antarctic coastal polynyas may have a key role for polar ecosystems as biologically active areas throughout the season within the sea-ice region despite inter and intra-polynya differences in environmental conditions

Modeled air-sea interactions around southeastern Greenland during extreme mesoscale wind events

The coast along the southern tip of Greenland is one of the windiest locations in the world due to strong mesoscale barrier winds and tip jets that form when synoptic scale flow interacts with the topography of Greenland. This study addresses how modeled mesoscale wind events around southeastern Greenland impact air-sea interactions and the ocean\u27s response to this forcing. Case study comparisons between Weather Research and Forecasting (WRF) model simulations run at four different resolutions (100 km, 50 km, 25 km, 10 km), in-situ observations, and QuikSCAT satellite data indicate that resolutions of 50 km and higher explicitly represent mesoscale winds. However, 10 km resolution is required to capture the vertical and horizontal structure of wind jets and to produce the greatest magnitude latent and sensible heat fluxes. The self-organizing map (SOM) algorithm was used to identify and classify the range of 10 m wind patterns present during ten winters (1997-2007, NDJFM) in the ECMWF Interim Reanalysis (ERA-I) and 50 km WRF simulation. WRF simulated patterns with strong barrier-parallel flow more frequently than ERA-I, and WRF also had faster coastal winds than ERA-I during all types of strong wind events. The largest turbulent flux differences occur over the marginal ice zone where the near-surface atmospheric state depends on specified sea ice thickness in each model. The SOM algorithm was then used to identify 12 wind patterns present during 20 winters (1990-2010, NDJFM) in the fully coupled Regional Arctic System Model (RASM). For all wind patterns the ocean loses buoyancy, primarily from turbulent sensible and latent heat fluxes. Patterns with westerly winds at Cape Farewell had the largest buoyancy loss over the Irminger and Labrador Seas while patterns with easterly flow at Cape Farewell have large buoyancy loss along the sea ice edge in the Denmark Strait and a secondary maximum immediately west of Cape Farewell. The ocean mixed layer is anomalously deep for wind patterns that have northerly flow with either easterly or westerly winds at Cape Farewell; mixed layer deepening is positively correlated to the frequency of those patterns and of greater magnitude for longer duration events