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The weighted mean temperature (Tm) is an important parameter to convert the tropospheric zenith wet delay (ZWD) extracted from the global navigation satellite system (GNSS) signal into precipitable water vapor (PWV). The computation of Tm requires vertical or ground meteorological parameters. However, most GNSS stations in Greenland lack in situ meteorological data, resulting in an accuracy degradation of the derived PWV. Using the most recent ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) from 1990 to 2018, we extract the principal components from a large amount of reanalysis data and then model Tm using a data-driven principal component analysis (PCA) method. In comparison with classic periodic modeling approaches, our PCA model uses fewer parameters and considers temperature fluctuation with height. The proposed model is validated using observations from 11 radiosonde stations in Greenland from 2015 to 2019. The model’s bias and RMSE are − 0.110 and 4.447 K, respectively. The new model is also compared to the global pressure and temperature 3 (GPT3) and GTrop traditional grid models. The bias is reduced by 0.339 and 0.422 K, respectively, and the RMSE is reduced by 0.197 and 0.045 K, respectively. [ABSTRACT FROM AUTHOR]

Nanosized hybrid cathode materials, LiMnFePO with olivine structure anchoring on the graphene matrices, were facilely prepared by employing a modified microwave-assisted solvothermal method. Many measurements such as XRD, SEM, TEM, EDS, Raman spectra and XPS have been utilized to identify their physicochemical properties. Electron microscopy analyses revealed that the widely distributed LiMnFePO nanorods were selectively and homogeneously grown on graphene sheets with rod length of 100-200 nm and diameter of 30-50 nm. In particular, it was fully improved that the deliberate additions of conductive matrix, graphene oxide, have facilitated the specific growth of LiMnFePO and therefore improved their homogeneity and morphology to form a huge electric network. Electrochemical assessments indicated that the as-synthesized materials delivered an initial discharge capacity of 159.8 mAh g at 0.1 C and even 81.6 mAh g at 20 C, meanwhile maintained their excellent rate capability and cycling ability, about 91.7% capacity retention after 80 cycles at 1 C. Theoretically speaking, the excellent electrochemical performance maybe makes these nanosized LiMnFePO cathode materials a potential candidate for the practical implications in high-power devices and energy storage systems. [ABSTRACT FROM AUTHOR]

Using atmospheric observational data from 1998 to 2013, station rainfall data, TRMM (Tropical Rainfall Measuring Mission) data, as well as annual statistics for the plateau vortex and shear line, the joint activity features of sustained departure plateau vortexes (SDPVs) and southwest vortexes (SWVs) are analyzed. Some new and useful observational facts and understanding are obtained about the joint activities of the two types of vortex. The results show that: (1) The joint active period of the two vortexes is from May to August, and mostly in June and July. (2) The SDPVs of the partnership mainly originate near Zaduo, while the SWVs come from Jiulong. (3) Most of the two vortexes move in almost the same direction, moving eastward together with the low trough. The SDPVs mainly act in the area to the north of the Yangtze River, while the SWVs are situated across the Yangtze River valley. (4) The joint activity of the two vortexes often produces sustained regional heavy rainfall to the south of the Yellow River, influencing wide areas of China, and even as far as the Korean Peninsula, Japan and Vietnam. (5) Most of the two vortexes are baroclinic or cold vortexes, and they both become strengthened in terms of their joint activity. (6) When the two vortexes move over the sea, their central pressure descends and their rainfall increases, especially for SWVs. (7) The two vortexes might spin over the same area simultaneously when there are tropical cyclones in the eastern and southern seas of China, or move southward together if a tropical cyclone appears near Hainan Island. [ABSTRACT FROM AUTHOR]

By using the twice-daily atmospheric observation data from 1998 to 2012, station rainfall data, Tropical Rainfall Measure Mission (TRMM) data, as well as the plateau vortex and shear line year book, characteristics of the sustained departure plateau vortexes (SDPVs) are analyzed. Some new useful observational facts and understanding are obtained about the SDPV activities. The following results are obtained. (1) The active period of SDPVs is from June to August, most in July, unlike that of the unsustained departure plateau vortexes (UDPVs), which have same occurrence frequencies in the three summer months. (2) The SDPVs, generated mainly in the Qumalai neighborhood and situated in a sheared surrounding, move eastward or northeastward, while the UDPVs are mainly led by the upper-level trough, and move eastward or southeastward. (3) The SDPVs influence wide areas of China, even far to the Korean Peninsula, Japan, and Vietnam. (4) The SDPVs change their intensities and properties on the way to the east. Most of them become stronger and produce downpour or sustained regional rainstorms to the south of Yellow River. (5) The longer the SDPV sustains, the more baroclinity it has. (6) When an SDPV moves into the sea, its central pressure descends and rainfall increases in all probability. (7) An SDPV might spin over the bend of the Yellow River when there exists a tropical cyclone in the East China Sea. It could also move oppositely to a landed tropical low pressure originated from the sea to the east of Taiwan or from the South China Sea. [ABSTRACT FROM AUTHOR]

Hilly-land satellite pixel-scale aerodynamic surface temperatures (AdST) are investigated using LAS (Large Aperture Scintillometer) and meteorological observations during 21–22 May 2001, indicating that the calculated temperatures are predominantly subject to estimated roughness lengths and, to a less extent, to estimated Bowen ratios, with errors to within 3.0 K between the AdST calculations and hilly radiometric surface temperatures retrieved from satellite data with the split window model. The errors depend heavily on the model used and the zenith angles and azimuth of the satellite and sun with respect to the observational site. [ABSTRACT FROM AUTHOR]

Titania-supported palladium–copper bimetallic catalysts (Pd–Cu/P25) are prepared by liquid-phase chemical reduction method and then applied in liquid-phase catalytic reduction of nitrite ions (NO2-). Compared with the conventional impregnation method, which usually needs a post-thermal reduction procedure to eliminate the introduced anions, liquid-phase chemical reduction at ambient temperature was proved to inhibit the aggregation of metal active components by means of TEM and DSC analysis in this work, and the catalyst exhibited superior catalytic activity. The conversion of nitrite reached a high level (1×10-4 mol min-1} gcat-1) and is about 14 times than that reported recently. The influences on the conversion of NO2- by support materials and the molar ratio of palladium to copper are also investigated, and further, the reaction mechanisms are discussed according to the characterization results of XPS and in situ FT-IR. [ABSTRACT FROM AUTHOR]