The role of ozone atmosphere-snow gas exchange on polar, boundary-layer tropospheric ozone ? a review and sensitivity analysis

International audienceRecent research on snowpack processes and atmosphere-snow gas exchange has demonstrated that chemical and physical interactions between the snowpack and the overlaying atmosphere have a substantial impact on the composition of the lower troposphere. These observations also imply that ozone deposition to the snowpack possibly depends on parameters including the quantity and composition of deposited trace gases, solar irradiance, snow temperature and the substrate below the snowpack. Current literature spans a remarkably wide range of ozone deposition velocities (vdO3); several studies even reported positive ozone fluxes out of the snow. Overall, published values range from ~?

Equidimensional modelling of flow and transport processes in fractured porous systems I

Flow and transport in fractured porous media play an important role for many environmental applications, e.g. the design of disposal systems for hazardous waste. The different hydraulic properties of the fractures and the surrounding rock matrix have a strong influence on the behaviour of the physical processes existing on site. In the two papers of this conference, we will present a new numerical concept to describe saturated flow and transport processes in arbitrarily fractured porous media. We will use an equidimensional approach where fracture and matrix are discretized with elements of the same dimension. To solve the problem, we developed a two-level multigrid method based on a hierarchical decomposition into a fracture problem and a matrix problem. This decoupled treatment of fracture and matrix allows us to handle the locally governing physical processes appropriately. In this paper we will also present convergence comparisons with classical multigrid and algebraic multigrid methods (AMG). In Neunhäuserer et al. (this issue, part II) we will discuss the effect of equidimensionality on the modelling results and the influence of the chosen transport discretisation technique

Equidimensional modelling of flow and transport processes in fractured porous systems II

In fractured formations, the vastly different hydraulic properties of fractures and porous matrix lead to a considerable mass exchange between fracture and matrix, strongly affecting the flow and transport conditions in the domain of interest. This plays an important role for many environmental applications, e.g. the design of disposal systems for hazardous waste. In two papers, we display a new numerical concept describing saturated flow and transport processes in arbitrarily fractured porous media. An equidimensional approach is developed using elements of the same dimension for fracture and matrix discretisation. In Gebauer et al. (this issue, part I) we introduced a two-level multigrid method based on a hierarchical decomposition designed to solve equidimensional fracture-matrix-problems. In this paper we will discuss the effect of equidimensionality on the modelling results. Furthermore, the influence of the chosen transport discretisation technique will be shown

Measurement of light absorbing particles in the snow of the Huaytapallana glacier in the central Andes of Peru and their effect on albedo and radiative forcing

The impact of light absorbing particles (LAPs), i.e. black carbon (BC) and dust, in the cryosphere, is receiving increasing attention in the scientific community, because they may be contributing to the accelerating retreat of glaciers. The Huaytapallana mountain range in the central region of Peru is vulnerable to this effect; it has been estimated that its glacier surface has decreased by 56% in the last 27 years. In this study, we present first measurements of LAPs, in terms of effective black carbon (eBC), in the surface snow (0-2cm deep) in the Huaytapallana glacier between November 2015 and October 2016. The eBC mass was obtained using the new thermo-optical Light Absorption Heating Method (LAHM). The average of eBC in the surface layer was 31.1 ± 22.2 ppb. Applying the Snow, Ice, and Aerosol Radiation (SNICAR) model we estimated a reduction in albedo from the eBC ranging from 0.6 to 5.0%. The radiative forcing (RF) of the eBC was calculated, to be on average 11.8±7.8 W m-2. During winter and spring seasons, it further increased by 157% and 134%, respectively, relative to the mean. Therefore, the impact of the eBC is an important factor in the retreat of the glacier Huaytapallana and must be considered in the hydrological prediction models of water availability

Geriatric Hip Fracture Quality Initiative

Introduction: Multiple studies demonstrate increased morbidity, mortality, and loss of independence after hip fractures in geriatric patients. The 1-year mortality rate after a hip fracture has been estimated at anywhere from 14% to 58%. Hip fractures are one of the most common injuries evaluated by the UNM Orthopedic department. Geriatric hip fracture protocols have shown improved outcomes at many other centers with regard to improved functionality and decreased morbidity. The goal of this initiative is to improve outcomes with regard to length of hospital stay, functionality after surgery, and as a result, decreased morbidity and mortality. Materials/methods: All deaths in the orthopedic department were reviewed and analyzed from June 2009 to July 2019. Deaths were identified from morbidity and mortality submissions and NSQIP data. The geriatric hip fracture protocol was developed and implemented in Fall 2019, with non-critical care patients being primarily admitted to orthopedics, with hospitalist co-management. Specific post-operative and pain order sets were developed for efficiency and improved standard of care. Results: Early results of the newly developed geriatric hip fracture protocol demonstrate decreased length of stay in the hospital and earlier time to surgical intervention. It is too early to determine if morbidity and mortality has seen any decrease, however this can be anticipated with earlier time to surgery and decreased time in the hospital. Conclusions: We identified a need and successfully developed an initiative to improve care for geriatric patients with hip fractures. Implementation of this protocol decreased length of hospital stay as well as time to surgery. The analysis of the effect of this protocol on overall morbidity and mortality is ongoing

Multimodal Analgesia in Orthopaedic Surgery and Presentation of a Comprehensive Postoperative Pain Protocol: A Review

Rising opioid use in the United States has now been termed an epidemic. Opioid use is associated with considerable morbidity, mortality, and cost to the healthcare system. Orthopaedic surgeons play a key role in the opioid epidemic by prescribing postoperative narcotics. Although our understanding of the quantity of narcotics to prescribe postoperatively for analgesia is progressing, there is still a paucity of data focused on routine postoperative pain protocols. The purpose of this article is to review the current options for both opioid and non-opioid analgesia and put forth a multisubspecialty orthopaedic protocol of postoperative pain. On the basis of study findings and the individual experiences of surgeons within our orthopaedic department, our comprehensive pain protocol includes the following considerations: use of non-steroidal antiinflammatory drugs on an individual basis, limited use of benzodiazepines, use of diazepam in only pediatric patients undergoing major procedures, lower doses of gabapentin after hip and knee arthroplasty, higher doses of gabapentin after spine procedures, general use of oxycodone owing to its accessibility, use of isolated opioids rather than combined forms, and close collaboration with anesthesiologists for determining use of peripheral nerve block. Our resultant comprehensive pain protocol can provide orthopaedic surgeons with a framework to build upon, which will benefit greatly from future studies that examine narcotic use with specific procedures

Mehrgittermethoden und adaptive Diskretisierungsverfahren zur Simulation von Strömungs- und Transportprozessen in Kluftaquiferen

Im Zusammenhang mit der Deponierung von Schadstoffen und der Trinkwassergewinnung kommt der Simulation von Strömungs- und Transportprozessen in geklüfteten Bodenzonen eine große Bedeutung zu. Die oft sehr unterschiedlichen hydraulischen Eigenschaften von Kluftsystem und umgebender Gesteinsmatrix prägen das Strömungs- und Transportverhalten stark. Die daraus resultierende Heterogenität der physikalischen Prozesse ebenso wie die Komplexität der zugrundeliegenden Geometrie stellt hohe Anforderungen an die numerische Modellierung. In der vorliegenden Arbeit werden Modellansätze verwendet, die Klüfte und Matrix diskret beschreiben. Um die Nachteile der bisher verwendeten Kopplung von Elementen unterschiedlicher Dimension (keine Flußerhaltung am Kluft-Matrix-Übergang) zu vermeiden, werden Kluft und Matrix mit Elementen gleicher Dimension vernetzt, wobei in den Klüften degenerierte Elemente zugelassen werden. Alle weiteren Bausteine des Lösungsprozesses müssen daher robust gegenüber verschwindender Kluftweite (reduziertes Problem) sein. Die Diskretisierung der Strömungsgleichung wird mit einem Standard-Galerkin-Finite-Elemente-Verfahren durchgeführt, für die Transportgleichung wird ein modifiziertes Boxverfahren eingesetzt. Zur Lösung der Strömungsgleichung wird ein neuartiges Mehrgitterverfahren verwendet, das eine hierarchische Zerlegung des Lösungsraums in einen Kluft- und einen Matrixraum beinhaltet. Dies ermöglicht zu einem späteren Zeitpunkt die Anwendung unterschiedlicher, an den jeweils dominanten physikalischen Prozeß angepaßter Diskretisierungsverfahren in Kluft und Matrix

Free-troposphere ozone and carbon monoxide over the North Atlantic for 2001-2011

In situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in the Azores, Portugal, are analyzed together with results from an atmospheric chemical transport model (GEOS-Chem) and satellite remote sensing data (AIRS (Atmospheric Infrared Sounder) for CO, and TES (Tropospheric Emission Spectrometer) for O3) to examine the evolution of free-troposphere CO and O3 over the North Atlantic for 2001-2011. GEOS-Chem captured the seasonal cycles for CO and O3 well but significantly underestimated the mixing ratios of CO, particularly in spring. Statistically significant (using a significance level of 0.05) decreasing trends were found for both CO and O3 based on harmonic regression analysis of the measurement data. The best estimates of the possible trends for CO and O3 measurements are -0.31 ± 0.30 (2-σ) ppbv yr-1 and -0.21 ± 0.11 (2-σ) ppbv yr-1, respectively. Similar decreasing trends for both species were obtained with GEOS-Chem simulation results. The most important factor contributing to the decreases in CO and O3 at PMO over the past decade is the decline in anthropogenic emissions from North America, which more than compensate for the impacts from increasing Asian emissions. It is likely that climate change in the past decade has also affected the intercontinental transport of O3

Water-side turbulence enhancement of ozone deposition to the ocean

A parameterization for the deposition velocity of an ocean-reactive atmospheric gas (such as ozone) is developed. The parameterization is based on integration of the turbulent-molecular transport equation (with a chemical source term) in the ocean. It extends previous work that only considered reactions within the oceanic molecular sublayer. The sensitivity of the ocean-side transport to reaction rate and wind forcing is examined. A more complicated case with a much more reactive thin surfactant layer is also considered. The full atmosphere-ocean deposition velocity is obtained by matching boundary conditions at the interface. For an assumed ocean reaction rate of 103 s¿1, the enhancement for ozone deposition by oceanic turbulence is found to be up to a factor of three for meteorological data obtained in a recent cruise off the East Coast of the U.S