Abstract. Current estimates of the terrestrial carbon fluxes in Asia show large uncertainties particularly in the boreal and mid-latitudes and in China. In this paper, we present an updated carbon flux estimate for Asia ("Asia" refers to lands as far west as the Urals and is divided into boreal Eurasia, temperate Eurasia and tropical Asia based on TransCom regions) by introducing aircraft CO 2 measurements from the CONTRAIL (Comprehensive Observation Network for Trace gases by Airline) program into an inversion modeling system based on the CarbonTracker framework. We estimated the averaged annual total Asian terrestrial land CO 2 sink was about −1.56 Pg C yr −1 over the period 2006-2010, which offsets about one-third of the fossil fuel emission from Asia (+4.15 Pg C yr −1 ). The uncertainty of the terrestrial uptake estimate was derived from a set of sensitivity tests and ranged from −1.07 to −1.80 Pg C yr −1 , comparable to the formal Gaussian error of ±1.18 Pg C yr −1 (1-sigma). The largest sink was found in forests, predominantly in coniferous forests (−0.64 ± 0.70 Pg C yr −1 ) and mixed forests (−0.14 ± 0.27 Pg C yr −1 ); and the second and third large carbon sinks were found in grass/shrub lands and croplands, accounting for −0.44 ± 0.48 Pg C yr −1 and −0.20 ± 0.48 Pg C yr −1 , respectively. The carbon fluxes per ecosystem type have large a priori Gaussian uncertainties, and the reduction of uncertainty based on assimilation of sparse observations over Asia is modest (8.7-25.5 %) for most individual ecosystems. The ecosystem flux adjustments follow the detailed a priori spatial patterns by design, which further increases the reliance on the a priori biosphere exchange model. The peak-to-peak amplitude of inter-annual variability (IAV) was 0.57 Pg C yr −1 ranging from −1.71 Pg C yr −1 to −2.28 Pg C yr −1 . The IAV analysis reveals that the Asian CO 2 sink was sensitive to climate variations, with the lowest uptake in 2010 concurrent with a summer flood and autumn drought and the largest CO 2 sink in 2009 owing to favorable temperature and plentifulPublished by Copernicus Publications on behalf of the European Geosciences Union. 5808 H. F. Zhang et al.: Estimating Asian terrestrial carbon fluxes precipitation conditions. We also found the inclusion of the CONTRAIL data in the inversion modeling system reduced the uncertainty by 11 % over the whole Asian region, with a large reduction in the southeast of boreal Eurasia, southeast of temperate Eurasia and most tropical Asian areas.

Soil moisture is a key variable in the process of land–atmosphere energy and water exchange. Currently, there are a large number of operational satellite-derived soil moisture products and reanalysis soil moisture products available. However, due to the lack of in situ soil moisture measurements over the Tibetan Plateau (TP), their accuracy and applicability are unclear. Based on the in situ measurements of the soil moisture observing networks established at Maqu, Naqu, Ali, and Shiquanhe (Sq) by the Institute of Tibetan Plateau Research, the Chinese Academy of Sciences, the Northwest Institute of Eco-Environmental Resources, the Chinese Academy of Sciences and the University of Twente over the TP, the accuracy and reliability of the European Space Agency Climate Change Initiative Soil Moisture version 4.4 (ESA CCI SM v4.4) soil moisture products and the European Centre for Medium-Range Weather Forecasts Reanalysis 5 (ERA5) soil moisture product were evaluated. The spatiotemporal distributions and interannual variations of the soil moisture were analyzed. Further, the climatological soil moisture changing trends across the TP were explored. The results show that with regard to the whole plateau, the combined product performs the best (unbiased root-mean-square error (ubRMSE) = 0.043 m3/m3, R = 0.66), followed by the active product (ubRMSE = 0.048 m3/m3, R = 0.62), the passive product (ubRMSE = 0.06 m3/m3, R = 0.61), and the ERA5 soil moisture product (ubRMSE = 0.067 m3/m3, R = 0.52). Considering the good spatiotemporal data continuity of the ERA5 soil moisture product, the ERA5 soil moisture data from 1979 to 2018 were used to analyze the climatological soil moisture changing trend for the entire TP surface. It was found that there was an increasing trend of soil moisture across the TP, which was consistent with the overall trends of increasing precipitation and decreasing evaporation. Moreover, the shrinkage of the cryosphere in conjunction with the background TP warming presumably contribute to soil moisture change.

Abstract. Estimation of land surface heat fluxes is important for energy and water cycle studies, especially on the Tibetan Plateau (TP), where the topography is unique and the land–atmosphere interactions are strong. The land surface heating conditions also directly influence the movement of atmospheric circulation. However, high-temporal-resolution information on the plateau-scale land surface heat fluxes has been lacking for a long time, which significantly limits the understanding of diurnal variations in land–atmosphere interactions. Based on geostationary and polar-orbiting satellite data, the surface energy balance system (SEBS) was used in this paper to derive hourly land surface heat fluxes at a spatial resolution of 10 km. Six stations scattered throughout the TP and equipped for flux tower measurements were used to perform a cross-validation. The results showed good agreement between the derived fluxes and in situ measurements through 3738 validation samples. The root-mean-square errors (RMSEs) for net radiation flux, sensible heat flux, latent heat flux and soil heat flux were 76.63, 60.29, 71.03 and 37.5 W m−2, respectively; the derived results were also found to be superior to the Global Land Data Assimilation System (GLDAS) flux products (with RMSEs for the surface energy balance components of 114.32, 67.77, 75.6 and 40.05 W m−2, respectively). The diurnal and seasonal cycles of the land surface energy balance components were clearly identified, and their spatial distribution was found to be consistent with the heterogeneous land surface conditions and the general hydrometeorological conditions of the TP.

The limited detection of lead iodide (PbI2) to visible light hinders the further development of PbI2 in the field of optoelectronic applications. A photodetector based on PbI2 nanosheet/CdSe nanobelt (PbI2 NS/CdSe NB) is prepared for the first time. This composite structure exhibits broadband spectral photoresponse from ultraviolet (400 nm) to red (730 nm). More importantly, PbI2 NS/CdSe NB can promote the effective separation of electron–hole pairs and improve the photoelectric performance. Compared to single PbI2 NS, the PbI2 NS/CdSe NB photodetector exhibits higher light–dark current ratio (6.778 × 103 A), responsivity (347.57 A W−1), and detectivity (3.625 × 1015 Jones) under 490 nm illumination. A new strategy is provided here to design broadband and high‐performance photodetectors.

Downwelling shortwave radiation (DSWR) and downwelling longwave radiation (DLWR) are two important components of the Earth's surface radiation balance. In this study, the Heliosat method and the parameterization of Crawford and Duchon (1999, https://doi.org/10.1175/1520‐0450(1999)038<0474:AIPFEE>2.0.CO;2, hereafter CD99) were calibrated to make them suitable for estimation of DSWR and DLWR over the Tibetan Plateau (TP). Based on meteorological data, forcing data, and observations from polar‐orbiting satellites, the cloud albedo was calculated, and the clear‐sky index estimation scheme of the Heliosat method was improved. These improvements were then applied to derive 10‐day DSWR under all‐sky conditions over the TP by combining the clear‐sky shortwave radiation scheme with a clear‐sky index. The coefficient of the CD99 parameterization scheme clear‐sky DLWR was also calibrated, and 10‐day all‐sky DLWR was then determined and validated using ground‐based measurements. The spatiotemporal distributions of DSWR and DLWR were analyzed in detail. The results showed that the modified methods are efficient and applicable for downward radiation retrieval under all‐sky conditions over the TP with a reasonable accuracy. The mean percentage errors for DSWR and DLWR were −4.75% and 0.11%, respectively. The variation in the monthly DSWR (DLWR) showed a convex shape, with a maximum appearing in May (July). The spatial distributions of DLWR showed a southeast‐high and northwest‐low pattern. As the subsolar point moves northward, DSWR increases gradually and is clearly influenced by the Asian summer monsoon.

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Because of heterogeneous formations and multi-scale fractures, the accurate evaluation of microbial enhanced oil recovery is faced with numerous difficulties. For the purpose of evaluating the production performance of multi-slug microbial enhanced oil recovery, this work studied the influence of microbial activity on the properties of oil and porous rock and the effect of microbial slug compositions on oil recovery. A mathematical model was built on the basis of the experiment, using the Buckley–Leverett theory and production decline laws. The model is a combination of the characteristic curve of the water cut change and the exponential decline law of oil production, which could predict oilfield production performance, including water breakthrough time, cumulative oil production, and relationship between the water cut and water saturation of the flood front. In comparison to the numerical simulation method, this approach has no additional restrictions because of grid orientation effects, which were found to be suitable for predicting production performance of either large-scale or whole block. The predicted values of the model were compared to the measured values of a field test, indicating that the model predicted the performance of microbial enhanced oil recovery precisely. More specifically, the maximum prediction error of a single well was less than 10%, and the prediction error of the whole block was less than 3%, suggesting the suitability of the model in predicting production performance. In conclusion, it is believed that the multi-slug seems to be a better approach for enhanced oil recovery and that the mathematical model would accurately predict the production performance of microbial enhanced oil recovery.

Room-temperature phosphorescent (RTP) carbon dots (CDs) have promising applications in bioimaging, anticounterfeiting, and information encryption owing to their long lifetimes and wide Stokes shifts. Numerous researchers are interested in developing highly bright RTP CDs using environmentally friendly and safe synthesis processes (e.g., natural raw materials and zero-pollution production pathways). In this study, we successfully synthesized RTP CDs using a hydrothermal process employing natural vitamins as a raw material, ethylenediamine as a passivator, and boric acid as a phosphorescent enhancer, which is referred to as phosphorescent CD (PCD). The PCDs exhibit both bright blue fluorescence emission and green RTP emission, with a phosphorescence lifetime as long as 293 ms and an excellent green afterglow visible to the naked eye for up to 7.0 s. The total quantum yield is 12.69%. The phosphorescence quantum yield (PQY) is up to 5.15%. Based on the RTP performance, PCDs have been successfully employed for anticounterfeiting and information protection applications. The results of this study provide a green strategy for the scalable synthesis of RTP materials, which is a practical method for the fabrication of RTP materials with high efficiency and long afterglow lifetimes.