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  • 1
    Online Resource
    Online Resource
    Characterizing model errors in chemical transport modeling of methane: impact of model resolution in versions v9-02 of GEOS-Chem and v35j of its adjoint model
    Copernicus GmbH ; 2020
    In:  Geoscientific Model Development Vol. 13, No. 9 ( 2020-08-31), p. 3839-3862
    Details
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 13, No. 9 ( 2020-08-31), p. 3839-3862
    Abstract: Abstract. The GEOS-Chem simulation of atmospheric CH4 was evaluated against observations from the Thermal and Near Infrared Sensor for Carbon Observations Fourier Transform Spectrometer (TANSO-FTS) on the Greenhouse Gases Observing Satellite (GOSAT), the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), and the Total Carbon Column Observing Network (TCCON). We focused on the model simulations at the 4∘×5∘ and 2∘×2.5∘ horizontal resolutions for the period of February–May 2010. Compared to the GOSAT, TCCON, and ACE-FTS data, we found that the 2∘×2.5∘ model produced a better simulation of CH4, with smaller biases and a higher correlation to the independent data. We found large resolution-dependent differences such as a latitude-dependent XCH4 bias, with higher column abundances of CH4 at high latitudes and lower abundances at low latitudes at the 4∘×5∘ resolution than at 2∘×2.5∘. We also found large differences in CH4 column abundances between the two resolutions over major source regions such as China. These differences resulted in up to 30 % differences in inferred regional CH4 emission estimates from the two model resolutions. We performed several experiments using 222Rn, 7Be, and CH4 to determine the origins of the resolution-dependent errors. The results suggested that the major source of the latitude-dependent errors is excessive mixing in the upper troposphere and lower stratosphere, including mixing at the edge of the polar vortex, which is pronounced at the 4∘×5∘ resolution. At the coarser resolution, there is weakened vertical transport in the troposphere at midlatitudes to high latitudes due to the loss of sub-grid tracer eddy mass flux in the storm track regions. The vertical air mass fluxes are calculated in the model from the degraded coarse-resolution wind fields and the model does not conserve the air mass flux between model resolutions; as a result, the low resolution does not fully capture the vertical transport. This produces significant localized discrepancies, such as much greater CH4 abundances in the lower troposphere over China at 4∘×5∘ than at 2∘×2.5∘. Although we found that the CH4 simulation is significantly better at 2∘×2.5∘ than at 4∘×5∘, biases may still be present at 2∘×2.5∘ resolution. Their importance, particularly in regards to inverse modeling of CH4 emissions, should be evaluated in future studies using online transport in the native general circulation model as a benchmark simulation.
    Type of Medium: Online Resource
    ISSN: 1991-9603
    URL: Article
    DOI: 10.5194/gmd-13-3839-2020
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2456725-5
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  • 2
    Online Resource
    Online Resource
    Characterizing model errors in chemical transport modeling of methane: using GOSAT XCH〈sub〉4〈/sub〉 data with weak-constraint four-dimensional variational data assimilation
    Copernicus GmbH ; 2021
    In:  Atmospheric Chemistry and Physics Vol. 21, No. 12 ( 2021-06-24), p. 9545-9572
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 12 ( 2021-06-24), p. 9545-9572
    Abstract: Abstract. We examined biases in the global GEOS-Chem chemical transport model for the period of February–May 2010 using weak-constraint (WC) four-dimensional variational (4D-Var) data assimilation and dry-air mole fractions of CH4 (XCH4) from the Greenhouse gases Observing SATellite (GOSAT). The ability of the observations and the WC 4D-Var method to mitigate model errors in CH4 concentrations was first investigated in a set of observing system simulation experiments (OSSEs). We then assimilated the GOSAT XCH4 retrievals and found that they were capable of providing information on the vertical structure of model errors and of removing a significant portion of biases in the modeled CH4 state. In the WC 4D-Var assimilation, corrections were added to the modeled CH4 state at each model time step to account for model errors and improve the model fit to the assimilated observations. Compared to the conventional strong-constraint (SC) 4D-Var assimilation, the WC method was able to significantly improve the model fit to independent observations. Examination of the WC state corrections suggested that a significant source of model errors was associated with discrepancies in the model CH4 in the stratosphere. The WC state corrections also suggested that the model vertical transport in the troposphere at middle and high latitudes is too weak. The problem was traced back to biases in the uplift of CH4 over the source regions in eastern China and North America. In the tropics, the WC assimilation pointed to the possibility of biased CH4 outflow from the African continent to the Atlantic in the mid-troposphere. The WC assimilation in this region would greatly benefit from glint observations over the ocean to provide additional constraints on the vertical structure of the model errors in the tropics. We also compared the WC assimilation at 4∘ × 5∘ and 2∘ × 2.5∘ horizontal resolutions and found that the WC corrections to mitigate the model errors were significantly larger at 4∘ × 5∘ than at 2∘ × 2.5∘ resolution, indicating the presence of resolution-dependent model errors. Our results illustrate the potential utility of the WC 4D-Var approach for characterizing model errors. However, a major limitation of this approach is the need to better characterize the specified model error covariance in the assimilation scheme.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-21-9545-2021
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2092549-9
    detail.hit.zdb_id: 2069847-1
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  • 3
    Online Resource
    Online Resource
    Risk factors for myocarditis associated with immune checkpoint inhibitors using real-world clinical data.
    American Society of Clinical Oncology (ASCO) ; 2020
    In:  Journal of Clinical Oncology Vol. 38, No. 15_suppl ( 2020-05-20), p. e15100-e15100
    Details
    In: Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 38, No. 15_suppl ( 2020-05-20), p. e15100-e15100
    Abstract: e15100 Background: Immune checkpoint inhibitors (ICIs) can cause unique, high-grade immune-related adverse events. Although rare, ICI related myocarditis has the highest fatality rate (~50%). Cardiovascular monitoring is not routinely performed in patients on ICI treatment, thus risk factors remain unknown. Characterizing rare but fatal cardiac toxicities requires integration of real-world data. Methods: U.S claims data (IBM MarketScan) of over 30 million commercially insured individuals was leveraged to identify 2,687,301 cancer patients between 2011-2018. Patients ≥18 years of age treated with ICIs (targeting CTLA4 (ipilimumab) and/or the PD1 (nivolumab, pembrolizumab)/PDL1 (atezolizumab, avelumab, durvalumab) alone or in combination with ICI and/or chemotherapy were identified and followed until disenrollment. Myocarditis, comorbidities, and treatment details were identified using diagnosis and billing codes. Analyses included descriptive statistics and Cox proportional hazards regression. Results: 16,541 ICI treated cancer patients were included (median age 60; 58% male). Myocarditis was identified in 252 (1.5%) patients, majority (90%) ≥50 years old (median 63) with 12,040 person-years of follow up. 62% received anti-PD1 monotherapy, 12% anti-CTLA4, and 15% received combination treatment with other ICIs and/or chemotherapy. Most common cancer types were lung (48%), melanoma (25%), and renal cancer (14%). Cumulative incidence of myocarditis at 1 year was 2.06%; 95% CI (1.78-2.37), median onset of 80.5 days, 42% occurring within 60 days of treatment. By univariate analyses, age, cancer type, diabetes (DM), hypertension (HTN), kidney, liver disease, atrial fibrillation (AF) were related to myocarditis. Risk was lower in patients who received anti-CTLA4 monotherapy (HR: 0.490; 95% CI: 0.26-0.92; p = 0.0251). On multivariable regression analyses only age, cancer type (renal, lung cancer), comorbidities DM and liver disease were significantly associated with myocarditis (Table). Conclusions: This is the largest real-world longitudinal study for ICI associated myocarditis showing higher than reported incidence and identifiable risk factors. [Table: see text]
    Type of Medium: Online Resource
    ISSN: 0732-183X , 1527-7755
    URL: Article
    DOI: 10.1200/JCO.2020.38.15_suppl.e15100
    RVK:
    XA 52760
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Clinical Oncology (ASCO)
    Publication Date: 2020
    detail.hit.zdb_id: 2005181-5
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