Simulation of CO2 and CH4 seasonal cycles in Siberia

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所 2階 大会議

Adjoint of the global Eulerian-Lagrangian coupled atmospheric transport model (A-GELCA v1.0): development and validation

We present the development of the Adjoint of the Global Eulerian–Lagrangian Coupled Atmospheric (A-GELCA) model that consists of the National Institute for Environmental Studies (NIES) model as an Eulerian three-dimensional transport model (TM), and FLEXPART (FLEXible PARTicle dispersion model) as the Lagrangian Particle Dispersion Model (LPDM). The forward tangent linear and adjoint components of the Eulerian model were constructed directly from the original NIES TM code using an automatic differentiation tool known as TAF (Transformation of Algorithms in Fortran; http://www.FastOpt.com), with additional manual pre- and post-processing aimed at improving transparency and clarity of the code and optimizing the performance of the computing, including MPI (Message Passing Interface). The Lagrangian component did not require any code modification, as LPDMs are self-adjoint and track a significant number of particles backward in time in order to calculate the sensitivity of the observations to the neighboring emission areas. The constructed Eulerian adjoint was coupled with the Lagrangian component at a time boundary in the global domain. The simulations presented in this work were performed using the A-GELCA model in forward and adjoint modes. The forward simulation shows that the coupled model improves reproduction of the seasonal cycle and short-term variability of CO2. Mean bias and standard deviation for five of the six Siberian sites considered decrease roughly by 1 ppm when using the coupled model. The adjoint of the Eulerian model was shown, through several numerical tests, to be very accurate (within machine epsilon with mismatch around to ±6 e−14) compared to direct forward sensitivity calculations. The developed adjoint of the coupled model combines the flux conservation and stability of an Eulerian discrete adjoint formulation with the flexibility, accuracy, and high resolution of a Lagrangian backward trajectory formulation. A-GELCA will be incorporated into a variational inversion system designed to optimize surface fluxes of greenhouse gases

Inverse modeling of pan-Arctic methane emissions at high spatial resolution: what can we learn from assimilating satellite retrievals and using different process-based wetland and lake biogeochemical models?

Understanding methane emissions from the Arctic, a fast-warming carbon reservoir, is important for projecting future changes in the global methane cycle. Here we optimized methane emissions from north of 60&deg; N (pan-Arctic) regions using a nested-grid high-resolution inverse model that assimilates both high-precision surface measurements and column-average SCanning Imaging Absorption spectroMeter for Atmospheric CHartogrphY (SCIAMACHY) satellite retrievals of methane mole fraction. For the first time, methane emissions from lakes were integrated into an atmospheric transport and inversion estimate, together with prior wetland emissions estimated with six biogeochemical models. In our estimates, in 2005, global methane emissions were in the range of 496.4&ndash;511.5 Tg yr-1, and pan-Arctic methane emissions were in the range of 11.9&ndash;28.5 Tg yr-1. Methane emissions from pan-Arctic wetlands and lakes were 5.5&ndash;14.2 and 2.4&ndash;14.2 Tg yr-1, respectively. Methane emissions from Siberian wetlands and lakes are the largest and also have the largest uncertainty. Our results indicate that the uncertainty introduced by different wetland models could be much larger than the uncertainty of each inversion. We also show that assimilating satellite retrievals can reduce the uncertainty of the nested-grid inversions. The significance of lake emissions cannot be identified across the pan-Arctic by high-resolution inversions, but it is possible to identify high lake emissions from some specific regions. In contrast to global inversions, high-resolution nested-grid inversions perform better in estimating near-surface methane concentrations.</p

Methane Emission Estimates by the Global High-Resolution Inverse Model Using National Inventories

We present a global 0.1° × 0.1° high-resolution inverse model, NIES-TM-FLEXPART-VAR (NTFVAR), and a methane emission evaluation using the Greenhouse Gas Observing Satellite (GOSAT) satellite and ground-based observations from 2010–2012. Prior fluxes contained two variants of anthropogenic emissions, Emissions Database for Global Atmospheric Research (EDGAR) v4.3.2 and adjusted EDGAR v4.3.2 which were scaled to match the country totals by national reports to the United Nations Framework Convention on Climate Change (UNFCCC), augmented by biomass burning emissions from Global Fire Assimilation System (GFASv1.2) and wetlands Vegetation Integrative Simulator for Trace Gases (VISIT). The ratio of the UNFCCC-adjusted global anthropogenic emissions to EDGAR is 98%. This varies by region: 200% in Russia, 84% in China, and 62% in India. By changing prior emissions from EDGAR to UNFCCC-adjusted values, the optimized total emissions increased from 36.2 to 46 Tg CH4 yr−1 for Russia, 12.8 to 14.3 Tg CH4 yr−1 for temperate South America, and 43.2 to 44.9 Tg CH4 yr−1 for contiguous USA, and the values decrease from 54 to 51.3 Tg CH4 yr−1 for China, 26.2 to 25.5 Tg CH4 yr−1 for Europe, and by 12.4 Tg CH4 yr−1 for India. The use of the national report to scale EDGAR emissions allows more detailed statistical data and country-specific emission factors to be gathered in place compared to those available for EDGAR inventory. This serves policy needs by evaluating the national or regional emission totals reported to the UNFCCC

Methane Emission Estimates by the Global High-Resolution Inverse Model Using National Inventories

We present a global 0.1° × 0.1° high-resolution inverse model, NIES-TM-FLEXPART-VAR (NTFVAR), and a methane emission evaluation using the Greenhouse Gas Observing Satellite (GOSAT) satellite and ground-based observations from 2010–2012. Prior fluxes contained two variants of anthropogenic emissions, Emissions Database for Global Atmospheric Research (EDGAR) v4.3.2 and adjusted EDGAR v4.3.2 which were scaled to match the country totals by national reports to the United Nations Framework Convention on Climate Change (UNFCCC), augmented by biomass burning emissions from Global Fire Assimilation System (GFASv1.2) and wetlands Vegetation Integrative Simulator for Trace Gases (VISIT). The ratio of the UNFCCC-adjusted global anthropogenic emissions to EDGAR is 98%. This varies by region: 200% in Russia, 84% in China, and 62% in India. By changing prior emissions from EDGAR to UNFCCC-adjusted values, the optimized total emissions increased from 36.2 to 46 Tg CH4 yr−1 for Russia, 12.8 to 14.3 Tg CH4 yr−1 for temperate South America, and 43.2 to 44.9 Tg CH4 yr−1 for contiguous USA, and the values decrease from 54 to 51.3 Tg CH4 yr−1 for China, 26.2 to 25.5 Tg CH4 yr−1 for Europe, and by 12.4 Tg CH4 yr−1 for India. The use of the national report to scale EDGAR emissions allows more detailed statistical data and country-specific emission factors to be gathered in place compared to those available for EDGAR inventory. This serves policy needs by evaluating the national or regional emission totals reported to the UNFCCC

Healing and Ritual Imagination in Chinese Medicine: The Multiple Interpretations of Zhuyou

In the Chinese medical corpus, ritual healing largely fell under the rubric of zhuyou 祝由 to uncover and expel the unknown, imperceptible, and occult causes of illness. Often dealing with uncertain or incurable cases, zhuyou remained at the cutting-edge of contemporary medicine. For a rising medical elite after the Northern Song, zhuyou was the branch of medicine to flexibly incorporate and critique the variety of ritual therapies into orthodox practice. Zhuyou employed prayer, incantations, talismans, gestures, and drugs in a nuanced clinical encounter to reveal the hidden root of disorder ranging from a blockage of qi, spirit possession, emotional imbalance, or loss of virtue. These rituals opened an imaginative space for therapeutic play where patients and healers could use spiritual proxies and props to address difficult emotions or issues that were often the hidden cause of affliction. The development of zhuyou also reflected the changing role of ritual in the history of Chinese medicine and the exchanges among physicians, Daoist priests, and other ritual healers. The significance of ritual in Chinese medical history has largely remained unclear as most editions of medical classics republished since the early twentieth century excise relevant chapters and zhuyou manuscripts, until recently, were uncatalogued

Temporal Characteristics of CH4 Vertical Profiles Observed in the West Siberian Lowland Over Surgut From 1993 to 2015 and Novosibirsk From 1997 to 2015

We have carried out monthly flask sampling using aircraft, in the altitude range of 0-7 km, over the boreal wetlands in Surgut (61°N, 73°E; since 1993) and a pine forest near Novosibirsk (55°N, 83°E; since 1997), both located in the West Siberian Lowland (WSL). The temporal variation of methane (CH4) concentrations at all altitudes at both sites exhibited an increasing trend with stagnation during 2000-2006 as observed globally from ground-based networks. In addition to a winter maximum as seen at other remote sites in northern middle to high latitudes, another seasonal maximum was also observed in summer, particularly in the lower altitudes over the WSL, which could be attributed to emissions from the wetlands. Our measurements suggest that the vertical gradient at Surgut has been decreasing; the mean CH4 difference between 5.5 km and 1.0 km changed from 64 ± 5 ppb during 1995-1999 to 37 ± 3 ppb during 2009-2013 (mean ± standard error). No clear decline in the CH4 vertical gradient appeared at Novosibirsk. Simulations using an atmospheric chemistry-transport model captured the observed decrease in the vertical CH4 gradient at Surgut when CH4 emissions from Europe decreased but increased from the regions south of Siberia, for example, East and South Asia. At Novosibirsk, the influence of the European emissions was relatively small. Our results also suggest that the regional emissions around the WSL did not change significantly over the period of our observations

Country-Scale Analysis of Methane Emissions with a High-Resolution Inverse Model Using GOSAT and Surface Observations

We employed a global high-resolution inverse model to optimize the CH4 emission using Greenhouse gas Observing Satellite (GOSAT) and surface observation data for a period from 2011–2017 for the two main source categories of anthropogenic and natural emissions. We used the Emission Database for Global Atmospheric Research (EDGAR v4.3.2) for anthropogenic methane emission and scaled them by country to match the national inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC). Wetland and soil sink prior fluxes were simulated using the Vegetation Integrative Simulator of Trace gases (VISIT) model. Biomass burning prior fluxes were provided by the Global Fire Assimilation System (GFAS). We estimated a global total anthropogenic and natural methane emissions of 340.9 Tg CH4 yr−1 and 232.5 Tg CH4 yr−1, respectively. Country-scale analysis of the estimated anthropogenic emissions showed that all the top-emitting countries showed differences with their respective inventories to be within the uncertainty range of the inventories, confirming that the posterior anthropogenic emissions did not deviate from nationally reported values. Large countries, such as China, Russia, and the United States, had the mean estimated emission of 45.7 ± 8.6, 31.9 ± 7.8, and 29.8 ± 7.8 Tg CH4 yr−1, respectively. For natural wetland emissions, we estimated large emissions for Brazil (39.8 ± 12.4 Tg CH4 yr−1), the United States (25.9 ± 8.3 Tg CH4 yr−1), Russia (13.2 ± 9.3 Tg CH4 yr−1), India (12.3 ± 6.4 Tg CH4 yr−1), and Canada (12.2 ± 5.1 Tg CH4 yr−1). In both emission categories, the major emitting countries all had the model corrections to emissions within the uncertainty range of inventories. The advantages of the approach used in this study were: (1) use of high-resolution transport, useful for simulations near emission hotspots, (2) prior anthropogenic emissions adjusted to the UNFCCC reports, (3) combining surface and satellite observations, which improves the estimation of both natural and anthropogenic methane emissions over spatial scale of countries

Tracing Material Cycle Using Stable Isotopes : Carbon Monoxide from Automobile

We estimate up-to-date values of the average isotopic compositions of CO emitted from automobiles. In the estimation, we determined the isotopic compositions of CO in tail pipe exhaust for four gasoline automobiles and two diesel automobiles under varying conditions of both idling and running. While the dependence on the automobile manufacturer is little, each automobile equipped with functional catalytic converter exhibits a large temporal δ13C and δ18O variation. They tend to show 13C- and 18O-enrichment in accordance with the reduction of CO in exhaust, suggesting that the functional catalytic converter in engines enhances the δ13C and δ18O values of CO from tail pipes through a kinetic isotope effect during CO destruction. Assuming that automobiles run a modeled driving cycle, we estimated the average δ13C and δ18O of CO to be -23.8±0.8‰PDB and +25.3±1.0‰SMOW, respectively, for recent gasoline automobiles, and -19.5±0.7‰PDB and +15.1±1.0‰SMOW, respectively, for recent diesel automobiles. While the δ13C and δ18O values of recent gasoline automobiles coincide well with the isotopic compositions of source CO in present trunk road atmosphere estimated in this study, those are +4 to +6‰(δ13C) and +1 to +3‰(δ18O) higher than those reported previously and also those emitted from old, non-catalyst automobiles determined in this study. Recent improvements in functional catalytic converters have enhanced and will enhance the δ13C and δ18O values of CO from automobiles.International Symposium on "Dawn of a New Natural History - Integration of Geoscience and Biodiversity Studies". 5-6 March 2004. Sapporo, Japan