A highly selective, fluorescence resonance energy transfer (FRET) based aptasensor for enrofloxacin (ENR) detection was developed using core–shell upconversion nanoparticles as an energy donor and graphene oxide as an energy acceptor.
In order to more accurately study the change trend of land surface temperature in North America in recent years, we combined remote sensing and meteorological station data and used various restoration models to generate more accurate and more complete remote sensing land surface temperature data. Our data covered the North American continent from 2002 to 2018, with a spatial resolution of 0.05°×0.05°. In order to facilitate the statistics of the data, we set the projection mode of the data as World_Cylindrical_Equal_Area. We collated the data from different time dimensions, including month, season and year.
Abstract The precipitation over the eastern Tibetan Plateau (ETP, here defined as 29°–38°N, 91°–103°E) usually exhibits significant subseasonal variation during boreal summer. As the hot spot of land‐air interaction, the influences of ETP surface soil temperature ( T soil ) on the local precipitation through subseasonal land‐air interaction are still unclear but urgently needed for improving subseasonal prediction. Based on station and reanalysis datasets of 1979–2018, this study identifies the evident quasi‐biweekly (QBW) (9–30 days) periodic signal of ETP surface T soil variation during the early summer (May–June), which results from the anomalies of southeastward propagating mid‐latitude QBW waves in the mid‐to‐upper troposphere. The observational results further show that the maximum positive anomaly of precipitation over the ETP lags the warmest surface T soil by one phase at the QBW timescale, indicating that the warming surface T soil could enhance the subseasonal precipitation. The numerical experiments using the WRF model further demonstrate the effect of warming surface T soil on enhancing the local cyclonic and precipitation anomaly through increasing upward sensible heat flux, the ascending motion, and water vapor convergence at the QBW timescale. In contrast, the effect of soil moisture over the ETP is much weaker than T soil at the subseasonal timescale. This study confirms the importance of surface T soil over the ETP in regulating the precipitation intensity, which suggests better simulating the land thermal feedback is crucial for improving the subseasonal prediction.
Abstract Anomalous warming occurred over the Tibetan Plateau (TP) before and during the disastrous freezing rain and heavy snow hitting central and southern China in January 2008. The relationship between the TP warming and this extreme event is investigated with an atmospheric general circulation model. Two perpetual runs were performed. One is forced by the climatological mean sea surface temperatures in January as a control run; and the other has the same model setting as the control run except with an anomalous warming over the TP that mimics the observed temperature anomaly. The numerical results demonstrate that the TP warming induces favorable circulation conditions for the occurrence of this extreme event, which include the deepened lower-level South Asian trough, the enhanced lower-level southwesterly moisture transport in central-southern China, the lower-level cyclonic shear in the southerly flow over southeastern China, and the intensified Middle East jet stream in the middle and upper troposphere. Moreover, the anomalous TP warming results in a remarkable cold anomaly near the surface and a warm anomaly aloft over central China, forming a stable stratified inversion layer that favors the formation of the persistent freezing rain. The possible physical linkages between the TP warming and the relevant resultant circulation anomalies are proposed. The potential reason of the anomalous TP warming during the 2007–08 winter is also discussed.
A cellular automaton model based on dynamic floor-field is proposed by incorporating the effect of guiding information during evacuation process. The guiding information which is regarded as an important factor to pedestrian dynamics is depicted by introducing a parameter to adjust the static value and the moving direction of pedestrians to move to the emergency exit which is not familiarized by most of the people. In addition, rules are made to deal with conflicts and the following behavior is introduced during the simulation process. Applying the proposed model, simulation of a room with two exits is presented. The simulation result shows that: (i) Several typical phenomena during pedestrian evacuation have been observed during the simulation process, e.g. arching, alignment and clogging. (ii) In comparison to the static model, guiding information has been proved as a key factor to increase the evacuation efficiency which is approximately 43.75%.
Abstract The black carbon (BC) concentration over the southeastern Tibetan Plateau is modulated by atmospheric intraseasonal variations and in turn affects atmospheric circulation through both direct radiative atmospheric warming and surface cooling. Based on an intraseasonal dry‐wet phase transition over the southeastern Tibetan Plateau, we investigated the short‐term radiative‐dynamic coupling of the atmosphere with changes in the concentration of BC using both observations and numerical sensitivity experiments. The observed local concentrations of BC increased by >50% as a result of the enhanced convergence and upward migration associated with the development of an intraseasonal anomalous lower‐level cyclone. Calculations using an offline radiation transfer model showed that this increase in BC concentration led to ~4 W/m 2 of atmospheric radiative warming and ~2 W/m 2 of surface radiative cooling. Consequently, an anomalous lower‐level cyclone with an average wind speed of 0.5 m/s (~10% of the natural change from a dry to a wet phase) developed in a linear baroclinic model and an aerosol‐aware WRF model, which was mainly a result of the atmospheric warming while the surface cooling played only a minor role. Although the change in precipitation was small, cloud fraction was significantly increased due to the enhanced upward motion in the atmosphere. This warrants further studies of cloud adjustments to the BC concentration on both cloud fraction and microphysics aspects. The present study illustrates that consideration of aerosol‐circulation coupling is imperative to advance the subseasonal prediction of atmospheric circulation.
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