ALBERT

Description: The record length and quality of instantaneous peak flows (IPFs) have a great influence on flood design, but these high resolution flow data are not always available. The primary aim of this study is to compare different strategies to derive frequency distributions of IPFs using the HBV hydrologic model. The model is operated on a daily and an hourly time step for 18 catchments in the Aller-Leine basin, Germany. Subsequently, General Extreme Value (GEV) distributions are fitted to the simulated annual series of daily and hourly extreme flows. The resulting MDF quantiles from daily simulations are transferred into IPF quantiles using a multiple regression model, which enables a direct comparison with the simulated hourly quantiles. As long climate records with a high temporal resolution are not available, the hourly simulations require a disaggregation of the daily rainfall. Additionally, two calibrations strategies are applied: (a) a calibration on flow statistics; (b) a calibration on hydrographs. The results show that: (1) the multiple regression model is capable of predicting IPFs with the simulated MDFs; (2) both daily simulations with post-correction of flows and hourly simulations with pre-processing of precipitation enable a reasonable estimation of IPFs; (3) the best results are achieved using disaggregated rainfall for hourly modeling with calibration on flow statistics; (4) if the IPF observations are not sufficient for model calibration on flow statistics, the transfer of MDFs via multiple regressions is a good alternative for estimating IPFs. This article is protected by copyright. All rights reserved.

Description: Surface ozone (O3), carbon monoxide (CO), and total and speciated reactive nitrogen compounds (NOy, NO, NO2, PAN, HNO3, and particulate NO3−) were measured at Mount Waliguan (WLG; 36.28°N, 100.90°E, 3816 m above sea level (asl)) in the summer of 2006 to further understand the sources of ozone and reactive nitrogen and to investigate the partitioning of reactive nitrogen over the remote Qinghai-Tibetan Plateau. The mean mixing ratios of O3, CO, NOy, and daytime NO were 59 ppbv, 149 ppbv, 1.44 ppbv, and 71 pptv, respectively, which (except for NOy) were higher than those measured from a previous campaign in summer 2003, which is consistent with more frequent transport of anthropogenic pollution from central and eastern China in the measurement period of 2006 (55%) than that of 2003 (25%). The abnormally high values of NOy observed in 2003 were suspected to be due to the positive interference from ammonia (NH3) to the particular catalytic converter used in that study. Varied diurnal patterns were observed for the various NOy components. The ozone production efficiencies (ΔO3/ΔNOz), which were estimated from the slope of the O3-NOz scatterplot, were 7.7–11.3 for the polluted plumes from central and eastern China. The speciation of reactive nitrogen was investigated for the first time in the remote free troposphere in western China. PAN and particulate NO3− were the most abundant reactive nitrogen species at WLG, with average proportions of 32% and 31%, followed by NOx (24%) and HNO3 (20%). The relatively large contribution of particulate NO3− to NOy was due to the presence of high concentrations of NH3 and crustal particles, which favor the formation of particulate nitrate. An analysis of backward trajectories for the recent 10 years revealed that air masses from central and eastern China dominated the airflow at WLG in summer, suggesting strong impact of anthropogenic forcing on the surface ozone and other trace constituents on the Plateau.

Description: While ethylene crackers in Middle East and North America are shifting to ethane feedstocks and the volume of propylene production is becoming less, the market share of on-purpose propylene production technologies keeps on increasing. In Northeast Asia, due to the shortage of naphtha and natural gas, methanol-to-olefin and methanol-to-propylene technologies attract much attention. In addition, biochemical technologies are impinging the propylene downstream. Using starch, sugar, or biomass as raw materials, important industrial chemicals such as acrylic acid, butanol, and 1,3-propanediol can be produced. Propylene glycol and epichlorohydrine can be manufactured using glycerine, the byproduct of biodiesel. All these factors are changing the traditional C3 value chain profoundly. The status of the game-changing technologies related to the C3 value chain is presented. The relevant factors and the implications will be discussed. The traditional C3 chain is profoundly changed by diverse factors like the increasing on-purpose propylene production technologies and biotechnological processes. Alternative processes for the production of propylene and its derivatives have been aggressively pursued. The status of the game-changing technologies related to the C3 value chain and the relevant factors and implications are discussed.

Description: Regionalization methods have been effectively used in many hydrological studies, such as regional flood frequency analysis and low flows. However, there is no study to estimate the instantaneous peak flow (IPF) from maximum mean daily flow (MDF) using hydrological models with regionalized parameters. In this paper, the semi-distributed conceptual hydrological model HBV (Hydrologiska Byråns Vattenbalansavdelning) is operated on a daily time step for 18 catchments in the Aller-Leine basin, Germany. The model is calibrated on four different flow statistics, including winter/summer extremes distribution and flow duration curves. The model parameter values are predefined with the associated catchment descriptors by a transfer function. Two different regionalization schemes are investigated: one is carried out for all the catchments in the study area; the other one is only performed for several catchments within a cluster. The k-means algorithm is used to 12 different catchment characteristics from all 18 catchments as the partitional clustering algorithm. Subsequently, the General Extreme Value (GEV) distributions are fitted to the modeled MDFs, which are then transferred into IPF quantiles using a multiple regression model. The results show that: (1) the uncertainty resulted from model parameter regionalization for the estimation of IPFs is much smaller than the error when using MDFs instead of IPFs (2) the hydrological responses of the clustered catchments located in the flat areas are, in general, not as homogeneous as the ones in high elevated regions; (3) the model with the parameters derived from the same regionalization coefficients within a cluster performs better using the corresponding parameters estimated through all the catchments. This article is protected by copyright. All rights reserved.

Description: By applying an inversion algorithm to NO x satellite observations from OMI (Ozone Monitoring Instrument), monthly NO x emissions for a 10-year period (2007 to 2016) over Chinese seas are presented for the first time. No effective regulations on NO x emissions have been implemented for ships in China, which is reflected in the trend analysis of maritime emissions. The maritime emissions display a continuous increase rate of about 20% per year until 2012 and slow down to 3% after that. The seasonal cycle of shipping emissions has regional variations but all regions show lower emissions during winter. Simulations by an atmospheric chemistry transport model show a notable influence of maritime emissions on air pollution over coastal areas, especially in summer. The satellite-derived spatial distribution and the magnitude of maritime emissions over Chinese seas are in good agreement with bottom-up studies based on the Automatic Identification System of ships.

Description: Detrital zircon data have recently become available from many different portions of the Tibetan–Himalayan orogen. This study uses 13,441 new or existing U-Pb ages of zircon crystals from strata in the Lesser Himalayan, Greater Himalayan, and Tethyan sequences in the Himalaya, the Lhasa, Qiangtang, and Nan Shan–Qilian Shan–Altun Shan terranes in Tibet, and platformal strata of the Tarim craton to constrain changes in provenance through time. These constraints provide information about the paleogeographic and tectonic evolution of the Tibet–Himalaya region during Neoproterozoic to Mesozoic time. First-order conclusions are as follows: (1) Most ages from these crustal fragments are

Description: In this study, we use the magnetic field data measured by MESSENGER from 2011 to 2015 to investigate the average magnetic field morphology of Mercury's magnetotail in the down tail 0–3 R M (R M = 2440 km, Mercury's radius). It is found that Mercury has a terrestrial-like magnetotail, the magnetic field structure beyond 1.5 R M down tail is stretched significantly with typical lobe field 50 nT. A cross-tail current sheet separating the antiparallel field lines of lobes is present in the equatorial plane. The magnetotail width in north-south direction is about 5 R M , while the transverse width is about 4 R M . Thus, the magnetotail shows elongation along the north-south direction. At the cross-tail current sheet center, the normal component of magnetic field (10–20 nT) is much larger than the cross-tail component. The lobe-field-aligned component of magnetic field over current sheet can be well fitted by Harris sheet model. The curvature radius of field lines at sheet center usually reaches a minimum around midnight (100–200 km) with stronger current density (40–50 nA/m 2 ). While the curvature radius increases towards both flanks (400–600 km) with the decreased current density (about 20 nA/m 2 ). The half-thickness of current sheet around midnight is about 0.25 R M or 600 km, and the inner edge of current sheet is located at the down tail about 1.5 R M . Our results about the field structure in the near Mercury's tail show an evident dawn-dusk asymmetry as that found in the Earth's magnetotail, but reasons should be different. Possible reasons are discussed.