Methyl chloride as a tracer of tropical tropospheric air in the lowermost stratosphere inferred from IAGOS-CARIBIC passenger aircraft measurements

We present variations of methyl chloride (CH3Cl) and nitrous oxide (N2O) in the lowermost stratosphere (LMS) obtained from air samples collected by the In-service Aircraft for a Global Observing System-Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (IAGOS-CARIBIC) passenger aircraft observatory for the period 2008-2012. To correct for the temporal increase of atmospheric N2O, the CARIBIC N2O data are expressed as deviations from the long-term trend at the northern hemispheric baseline station Mauna Loa, Hawaii (Delta N2O).Delta N2O undergoes a pronounced seasonal variation in the LMS with a minimum in spring. The amplitude increases going deeper in the LMS (up to potential temperature of 40 K above the thermal tropopause), as a result of the seasonally varying subsidence of air from the stratospheric overworld. Seasonal variation of CH3Cl above the tropopause is similar in phase to that of Delta N2O. Significant correlations are found between CH3Cl and Delta N2O in the LMS from winter to early summer, both being affected by mixing between stratospheric air and upper tropospheric air. This correlation, however, disappears in late summer to autumn. The slope of the CH3Cl-Delta N2O correlation observed in the LMS allows us to determine the stratospheric lifetime of CH3Cl to be 35 +/- 7 years. Finally, we examine the partitioning of stratospheric air and tropical/extratropical tropospheric air in the LMS based on a mass balance approach using Delta N2O and CH3Cl. This analysis clearly indicates efficient inflow of tropical tropospheric air into the LMS in summer and demonstrates the usefulness of CH3Cl as a tracer of tropical tropospheric air

the Creative Commons Attribution 3.0 License. Atmospheric Chemistry and Physics

The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling stud

Pollution events observed during CARIBIC flights in the upper troposphere between South China and the Philippines

A strong pollution episode in the upper troposphere between South China and the Philippines was observed during CARIBIC flights in April 2007. Five pollution events were observed, where enhancements in aerosol and trace gas concentrations including CO, CO$_2$, CH$_4$, non-methane hydrocarbons (NMHCs) and halocarbons were observed along the flight tracks during four sequential flights. The importance of the contribution of biomass/biofuel burning was investigated using chemical tracers, emission factor analysis, back-trajectory analysis and satellite images. The Indochinese peninsula was identified as the probable source region of biomass/biofuel burning. However, enhancements in the urban/industrial tracer C$_2$Cl$_4$ during the events also indicate a substantial contribution from urban anthropogenic emissions. An estimation of the contribution of fossil fuel versus biomass/biofuel to the CO enhancement was made, indicating a biomass/biofuel burning contribution of ~54 to ~92% of the observed CO enhancements. Biomass/biofuel burning was found to be the most important source category during the sampling period

Real-World Evaluation of the Feasibility, Acceptability and Safety of a Remote, Self-Management Parkinson’s Disease Care Pathway: A Healthcare Improvement Initiative

Background: There is significant unmet need for effective and efficiently delivered care for people with Parkinson’s disease (PwP). We undertook a service improvement initiative to co-develop and implement a new care pathway, Home Based Care (HBC), based on supported self-management, remote monitoring and the ability to trigger a healthcare contact when needed. Objective: To evaluate feasibility, acceptability and safety of Home Based Care. Methods: We evaluated data from the first 100 patients on HBC for 6 months. Patient monitoring, performed at baseline and 6-monthly, comprised motor (MDS-UPDRS II and accelerometer), non-motor (NMSQ, PDSS-2, HADS) and quality of life (PDQ) measures. Care quality was audited against Parkinson’s UK national audit standards. Process measures captured feasibility. Acceptability was assessed using a mixed-methods approach comprising questionnaires and semi-structured interviews. Results: Between October 2019 and January 2021, 108 PwP were enrolled onto HBC, with data from 100 being available at 6 months. Over 90% of all questionnaires were returned, 97% were complete or had < 3 missing items. Reporting and communications occurred within agreed timeframes. Compared with baseline, after 6m on HBC, PD symptoms were stable; more PwP felt listened to (90% vs. 79%) and able to seek help (79% vs. 68%). HBC met 93% of national audit criteria. Key themes from the interviews included autonomy and empowerment. Conclusions: We have demonstrated acceptability, feasibility and safety of our novel remotely delivered Parkinson’s care pathway. Ensuring scalability will widen its reach and realize its benefits for underserved communities, enabling formal comparisons with standard care and cost-effectiveness evaluation

An evaluation of the performance of chemistry transport models by comparison with research aircraft observations. Part 1: Concepts and overall model performance

A rigorous evaluation of five global Chemistry-Transport and two Chemistry-Climate Models operated by several different groups in Europe, was performed. Comparisons were made of the models with trace gas observations from a number of research aircraft measurement campaigns during the four-year period 1995-1998. Whenever possible the models were run over the same four-year period and at each simulation time step the instantaneous tracer fields were interpolated to all coinciding observation points. This approach allows for a very close comparison with observations and fully accounts for the specific meteorological conditions during the measurement flights. This is important considering the often limited availability and representativity of such trace gas measurements. A new extensive database including all major research and commercial aircraft measurements between 1995 and 1998, as well as ozone soundings, was established specifically to support this type of direct comparison. Quantitative methods were applied to judge model performance including the calculation of average concentration biases and the visualization of correlations and RMS errors in the form of so-called Taylor diagrams. We present the general concepts applied, the structure and content of the database, and an overall analysis of model skills over four distinct regions. These regions were selected to represent various atmospheric conditions and to cover large geographical domains such that sufficient observations are available for comparison. The comparison of model results with the observations revealed specific problems for each individual model. This study suggests the further improvements needed and serves as a benchmark for re-evaluations of such improvements. In general all models show deficiencies with respect to both mean concentrations and vertical gradients of important trace gases. These include ozone, CO and NOx at the tropopause. Too strong two-way mixing across the tropopause is suggested to be the main reason for differences between simulated and observed CO and ozone values. The generally poor correlations between simulated and measured NOx values suggest that in particular the NOx input by lightning and the convective transport from the polluted boundary layer are still not well described by current parameterizations, which may lead to significant differences in the spatial and seasonal distribution of NOx in the models. Simulated OH concentrations, on the other hand, were found to be in surprisingly good agreement with measured values

An evaluation of the performance of chemistry transport models - Part 2: Detailed comparison with two selected campaigns

This is the second part of a rigorous model evaluation study involving five global Chemistry-Transport and two Chemistry-Climate Models operated by different groups in Europe. Simulated trace gas fields were interpolated to the exact times and positions of the observations to account for the actual weather conditions and hence for the specific histories of the sampled air masses. In this part of the study we focus on a detailed comparison with two selected campaigns, PEM-Tropics A and SONEX, contrasting the clean environment of the tropical Pacific with the more polluted North Atlantic region. The study highlights the different strengths and weaknesses of the models in accurately simulating key processes in the UT/LS region including stratosphere-troposphere-exchange, rapid convective transport, lightning emissions, radical chemistry and ozone production. Model simulated Radon, which was used as an idealized tracer for continental influence, was occasionally much better correlated with measured CO than simulated CO pointing towards deficiencies in the used biomass burning emission fields. The abundance and variability of HOx radicals is in general well represented in the models as inferred directly from the comparison with measured OH and HO2 and indirectly from the comparison with hydrogen peroxide concentrations. Components of the NOy family such as PAN, HNO3 and NO were found to compare less favorably. Interestingly, models showing good agreement with observations in the case of PEM-Tropics A often failed in the case of SONEX and vice versa. A better description of NOx and NOy emissions, chemistry and sinks is thought to be key to future model improvements with respect to the representation of chemistry in the UT/LS region

Investigation of chlorine radical chemistry in the Eyjafjallajkull volcanic plume using observed depletions in non-methane hydrocarbons

As part of the effort to understand volcanic plume composition and chemistry during the eruption of the Icelandic volcano Eyjafjallajkull, the CARIBIC atmospheric observatory was deployed for three special science flights aboard a Lufthansa passenger aircraft. Measurements made during these flights included the collection of whole air samples, which were analyzed for non-methane hydrocarbons (NMHCs). Hydrocarbon concentrations in plume samples were found to be reduced to levels below background, with relative depletions characteristic of reaction with chlorine radicals (Cl). Recent observations of halogen oxides in volcanic plumes provide evidence for halogen radical chemistry, but quantitative data for free halogen radical concentrations in volcanic plumes were absent. Here we present the first observation-based calculations of Cl radical concentrations in volcanic plumes, estimated from observed NMHC depletions. Inferred Cl concentrations were between 1.3 × 10 and 6.6 × 10 Cl cm. The relationship between NMHC variability and local lifetimes was used to investigate the ratio between OH and Cl within the plume, with [OH]/[Cl] estimated to be ∼37. Copyright 2011 by the American Geophysical Union

Long-Term Safety and Efficacy of Adalimumab in Patients with Noninfectious Intermediate Uveitis, Posterior Uveitis, or Panuveitis

Purpose: To evaluate long-term efficacy and safety of extended treatment with adalimumab in patients with noninfectious intermediate, posterior, or panuveitis. Design: Open-label, multicenter, phase 3 extension study (VISUAL III). Participants: Adults who had completed a randomized, placebo-controlled phase 3 parent trial (VISUAL I or II) without treatment failure (inactive uveitis) or who discontinued the study after meeting treatment failure criteria (active uveitis). Methods: Patients received subcutaneous adalimumab 40 mg every other week. Data were collected for ≤ 362 weeks. Adverse events (AEs) were recorded until 70 days after the last dose. Main Outcome Measures: Long-term safety and quiescence; other efficacy variables included inflammatory lesions, anterior chamber cell and vitreous haze grade, macular edema, visual acuity, and dose of uveitis-related systemic corticosteroids. Results: At study entry, 67% of patients (283/424) showed active uveitis and 33% (141/424) showed inactive uveitis; 60 patients subsequently met exclusion criteria, and 364 were included in the intention-to-treat analysis. Efficacy variables were analyzed through week 150, when approximately 50% of patients (214/424) remained in the study. Patients showing quiescence increased from 34% (122/364) at week 0 to 85% (153/180) at week 150. Corticosteroid-free quiescence was achieved by 54% (66/123) and 89% (51/57) of patients with active or inactive uveitis at study entry. Mean daily dose of systemic corticosteroids was reduced from 9.4 ± 17.1 mg/day at week 0 (n = 359) to 1.5 ± 3.9 mg/day at week 150 (n = 181). The percentage of patients who achieved other efficacy variables increased over time for those with active uveitis at study entry and was maintained for those with inactive uveitis. The most frequently reported treatment-emergent AEs of special interest were infections (n = 275; 79 events/100 patient-years [PY]); AEs and serious AEs occurred at a rate of 396 events/100 PY and 15 events/100 PY, respectively. Conclusions: Long-term treatment with adalimumab led to quiescence and reduced corticosteroid use for patients who entered VISUAL III with active uveitis and led to maintenance of quiescence for those with inactive uveitis. AEs were comparable with those reported in the parent trials and consistent with the known safety profile of adalimumab