Parameterizations of Surface Radiation in the Semiarid Grasslands of Inner Mongolia under Clear-Sky Conditions Using MODIS Data

A set of improved and efficient radiation parameterization schemes for surface radiation balance components under clear- sky conditions was developed by using general surface measurements and MODIS data. The set of schemes was then adapted for regions similar to the present study sites under different grazing intensities and varying degrees of drought in the semiarid grasslands of Inner Mongolia. Specifically, we mainly improved two schemes for estimating downward shortwave and longwave radiation at the surface, which could be applied to regions with certain degrees of drought. The validation datasets were from ground-based observations at various grazing sites during the growing season （May to September） of different drought years, 2005 and 2006. Through comparisons of parameterized versus measured radiation values, the increased or modified factors in the original schemes demonstrated improved estimation accuracy, and the rationalities of input parameters and variables were analyzed. The regional instantaneous net radiation estimations had root-mean-square errors of less than 30 W m-2 compared with ground measurements at the sites during the study period. The statistical results showed the improved schemes are suitable for estimating surface net radiation in regional semiarid areas during the growing season. Analyses of the sensitivity of the schemes to corresponding variables were conducted to ascertain the major error sources of the schemes and potential variables for improving the performance of the schemes in agreement with observations.

Simulation of arctic surface radiation and energy budget during the summertime using the single-column model

The surface heat budget of the Arctic Ocean （SHEBA） project has shown that the study of the surface heat budget characteristics is crucial to understanding the interface process and environmental change in the polar region. An arctic single - column model （ARCSCM） of Colorado University is used to simulate the arctic surface radiation and energy budget during the summertime. The simulation results are analyzed and compared with the SHEBA measurements. Sensitivity analyses are performed to test microphysical and radiative parameterizations in this model. The results show that the ARCSCM model is able to simulate the surface radiation and energy budget in the arctic during the summertime, and the different parameterizations have a significant influence on the results. The combination of cloud microphysics and RRTM parameterizations can fairly derive the surface solar shortwave radiation and downwelling longwave radiation flux. But this cloud microphysics parameterization scheme deviates notably from the simulation of surface sensible and latent heat flux. Further improvement for the parameterization scheme applied to the Arctic Regions is necessary.

Value-Added Products Derived from 15 Years of High-Quality Surface Solar Radiation Measurements at Xianghe,a Suburban Site in the North China Plain

Surface solar radiation(SSR) is a key component of the energy budget of the Earth’s surface, and it varies at different spatial and temporal scales. Considerable knowledge of how and why SSR varies is crucial to a better understanding of climate change, which surely requires long-term measurements of high quality. The objective of this study is to introduce a value-added SSR dataset from Oct 2004 to Oct 2019 based on measurements taken at Xianghe, a suburban site in the North China Plain;two value-added products based on the 1-minute SSR measurements are developed. The first is clear sky detection by using a machine learning model. The second is cloud fraction estimation derived from an effective semiempirical method. A “brightening” of global horizontal irradiance(GHI) was revealed and found to occur under both clear and cloudy conditions. This could likely be attributed to a reduction in aerosol loading and cloud fraction. This dataset could not only improve our knowledge of the variability and trend of SSR in the North China Plain, but also be beneficial for solar energy assessment and forecasting.

Increasing Surface UV Radiation in the Tropics and Northern Mid-Latitudes due to Ozone Depletion after 2010

Excessive exposure to ultraviolet(UV)radiation harms humans and ecosystems.The level of surface UV radiation had increased due to declines in stratospheric ozone in the late 1970s in response to emissions of chlorofluorocarbons.Following the implementation of the Montreal Protocol,the stratospheric loading of chlorine/bromine peaked in the late 1990s and then decreased;subsequently,stratospheric ozone and surface UV radiation would be expected to recover and decrease,respectively.Here,we show,based on multiple data sources,that the May–September surface UV radiation in the tropics and Northern Hemisphere mid-latitudes has undergone a statistically significant increasing trend[about 60.0 J m^(–2)(10 yr)^(–1)]at the 2σlevel for the period 2010–20,due to the onset of total column ozone(TCO)depletion[about−3.5 DU(10 yr)^(–1)].Further analysis shows that the declines in stratospheric ozone after 2010 could be related to an increase in stratospheric nitrogen oxides due to increasing emissions of the source gas nitrous oxide(N_(2)O).

The variability of surface radiation fluxes over landfast sea ice near Zhongshan station,east Antarctica during austral spring

Surface radiative fluxes over landfast sea ice off Zhongshan station have been measured in austral spring for five springs between 2010 and 2015.Downward and upward solar radiation vary diurnally with maximum amplitudes of 473 and 290 W m^(−2),respectively.The maximum and minimum long-wave radiation values of the mean diurnal cycle are 218 and 210 W m^(−2)for downward radiation,277 and 259 W m^(−2)for upward radiation and 125 and−52 W m^(−2)for net radiation.The albedo has a U-shaped mean diurnal cycle with a minimum of 0.64 at noon.Sea ice thickness is in the growth phase for most spring days,but can be disturbed by synoptic processes.The surface temperature largely determines the occurrence of ice melting.Surface downward and upward long-wave radiation show synoptic oscillations with a 5–8 day period and intraseasonal variability with a 12–45 day period.The amplitudes of the diurnal,synoptic and intraseasonal variability show some differences during the five austral springs considered here.The intraseasonal and synoptic variability of downward and upward long-wave radiation are associated with the variability of cloud cover and surface temperature induced by the atmospheric circulation.

NUMERICAL SIMULATION OF THE SURFACE RADIATION FIELD IN A HILLY COUNTRY

Based on the simulations of the topographic parameters(mean orientation,slope,and terrain screen angle)in a hilly land,discussion is made term by term of the technique for modelling of all components is done in the surface radiation balance over a rugged terrain,thus presenting a computer model for each com- ponent.In terms of experimental data,the components is calculated for the mesh grids of 100m×100 m each over 3.0×3.5 km^2 in the Zhaogongling,southern Dabie Mountains and a map is prepared showing the distribution of these components for January and July.Results show that the hilly-land surface radiation field matches the terrain element field quite well,which reveals the determining function of the latter,with orientational effect dominant in winter and terrain screen effect most significant in summer.The simulation technique presented is in principle applicable to the calculation for a radiation field in any kind of topogra- phy,thus providing a means for further exploration of hilly-land climate resource.

Propagation of Surface Wave Along a Thin Plasma Column and Its Radiation Pattern

Propagation of the surface waves along a two-dimensional plasma column and the far-field radiation patterns are studied in thin column approximation. Wave phase and attenuation coefficients are calculated for various plasma parameters. The radiation patterns are shown. Results show that the radiation patterns are controllable by flexibly changing the plasma length and other parameters in comparison to the metal monopole antenna. It is meaningful and instructional for the optimization of the plasma antenna design.

Coherent and tunable radiation with power enhancement from surface plasmon polaritons

Surface plasmon polaritons excited by an electron beam can be transformed into coherent and tunable light radiation waves with power enhancement in the simple structure of a metal film with a dielectric medium loading. In this paper, the process of the radiation transformation of this radiation, and the dependencies of the radiation characteristics on the parameters of the structure and the electron beam are studied in detail. The radiation power enhancement is greatly influenced by the beam energy and the film thickness in the infrared to ultraviolet frequency region. Up to 122 times radiation power enhancement and 6.5% radiation frequency tuning band can be obtained by optimizing the beam energy and the parameters of the film.

APPLICATION OF SURFACE GRAFTED POLY N-ISOPROPYL ACRYLAMIDE BY RADIATION TECHNOLOGY FOR PROTEIN SOLUTION CONCENTRATION

Poly N-isopropyl acrylamide (abbreviated as PNIPA) as a kind of thermally sensitive hydrogel is utilized to concentrate Bovin Serum Albumin (BSA) solution. In order to decrease its surface adsorption to BSA in aqueous solution, surface layer grafting of the gels by radiation technology was carried out. The results showed that hydroxyl propyl methacrylate (HPMA) grained gel exhibited a low level of BSA adsorption and still kept the original thermally sensitive properties of PNIPA hydrogels.

Advances in Estimation Methods of Surface Solar Radiation

Based on the main research results of estimation methods of surface solar radiation at home and abroad in recent decades, three commonly used estimation models of surface solar radiation have been introduced, and their principles, advantages and disadvantages have been analyzed to provide scientific references for further study of surface solar radiation in future.

Advances in Monitorinq Methods of Downward Surface Net Radiation

Downward surface net radiation,the net energy of the earth's surface obtained through shortwave and longwave radiation process,is the main driving force for material and energy cycle in the whole earth system.In this study,the main research results of monitoring methods of downward surface net radiation at home and abroad in recent decades have been summarized,and main remote sensing radiation products produced according to various sensors have been introduced.Moreover,the monitoring methods of downward shortwave and long-wave radiation have been discussed,and their principles,advantages and disadvantages have been analyzed to provide scientific references for further study of downward surface solar net radiation in future.

Observation of selective surface element substitution in FeTe_(0.5)Se_(0.5) superconductor thin film exposed to ambient air by synchrotron radiation spectroscopy

A systematic investigation of oxidation on a superconductive Fe Te_（0.5）Se_（0.5）thin film,which was grown on Nb-doped SrTiO_3（001） by pulsed laser deposition,has been carried out.The sample was exposed to ambient air for one month for oxidation.Macroscopically,the exposed specimen lost its superconductivity due to oxidation.The specimen was subjected to in situ synchrotron radiation photoelectron spectroscopy（PES） and x-ray absorption spectroscopy（XAS） measurements following cycles of annealing and argon ion etching treatments to unravel what happened in the electronic structure and composition after exposure to air.By the spectroscopic measurements,we found that the as-grown FeTe_（0.5）Se_（0.5）superconductive thin film experienced an element selective substitution reaction.The oxidation preferentially proceeds through pumping out the Te and forming Fe–O bonds by O substitution of Te.In addition,our results certify that in situ vacuum annealing and low-energy argon ion etching methods combined with spectroscopy are suitable for depth element and valence analysis of layered structure superconductor materials.

The quantum nonthermal radiation and horizon surface gravity of an arbitrarily accelerating black hole with electric charge and magnetic charge

Using a new tortoise coordinate transformation,we discuss the quantum nonthermal radiation characteristics near an event horizon by studying the Hamilton-Jacobi equation of a scalar particle in curved space-time,and obtain the event horizon surface gravity and the Hawking temperature on that event horizon.The results show that there is a crossing of particle energy near the event horizon.We derive the maximum overlap of the positive and negative energy levels.It is also found that the Hawking temperature of a black hole depends not only on the time,but also on the angle.There is a problem of dimension in the usual tortoise coordinate,so the present results obtained by using a correct-dimension new tortoise coordinate transformation may be more reasonable.

Satellite-Based Estimation of Daily Average Net Radiation under Clear-Sky Conditions

ABSTRACT Daily average net radiation （DANR） is an important variable for estimating evapotranspiration from satellite data at regional scales, and is used for atmospheric and hydrologic modeling, as well as ecosystem management. A scheme is proposed to estimate the DANR over large heterogeneous areas under clear-sky conditions using only remotely sensed data. The method was designed to overcome the dependence of DANR estimates on ground data, and to map spatially consistent and reasonably distributed DANR, by using various land and atmospheric data products retrieved from MODIS （Moderate Resolution Imaging Spectroradiometer） data. An improved sinusoidal model was used to retrieve the diurnal variations of downward shortwave radiation using a single instantaneous value from satellites. The downward shortwave component of DANR was directly obtained from this instantaneous value, and the upward shortwave component was estimated using satellite-derived albedo products. Four observations of air temperature from MOD07_L2 and MYD07_L2 data products were used to derive the downward longwave component of DANR, while the upward longwave component was estimated using the land surface temperature （LST） and the surface emissivity from MOD1 l_L2. Compared to in situ observations at the cropland and grassland sites located in Tongyu, northern China, the root mean square error （RMSE） of DANR estimated for both sites under clear-sky conditions was 37 W m-2 and 40 W m-2, respectively. The errors in estimation of DANR were comparable to those from previous satellite-based methods. Our estimates can be used for studying the surface radiation balance and evapotranspiration.

An evaluation of the Arctic clouds and surface radiative fluxes in CMIP6 models

To assess the performances of state-of-the-art global climate models on simulating the Arctic clouds and surface radiation balance,the 2001–2014 Arctic Basin surface radiation budget,clouds,and the cloud radiative effects(CREs)in 22 coupled model intercomparison project 6(CMIP6)models are evaluated against satellite observations.For the results from CMIP6 multi-model mean,cloud fraction(CF)peaks in autumn and is lowest in winter and spring,consistent with that from three satellite observation products(Cloud Sat-CALIPSO,CERESMODIS,and APP-x).Simulated CF also shows consistent spatial patterns with those in observations.However,almost all models overestimate the CF amount throughout the year when compared to CERES-MODIS and APP-x.On average,clouds warm the surface of the Arctic Basin mainly via the longwave(LW)radiation cloud warming effect in winter.Simulated surface energy loss of LW is less than that in CERES-EBAF observation,while the net surface shortwave(SW)flux is underestimated.The biases may result from the stronger cloud LW warming effect and SW cooling effect from the overestimated CF by the models.These two biases compensate each other,yielding similar net surface radiation flux between model output(3.0 W/m2)and CERES-EBAF observation(6.1 W/m2).During 2001–2014,significant increasing trend of spring CF is found in the multi-model mean,consistent with previous studies based on surface and satellite observations.Although most of the 22 CMIP6 models show common seasonal cycles of CF and liquid water path/ice water path(LWP/IWP),large inter-model spreads exist in the amounts of CF and LWP/IWP throughout the year,indicating the influences of different cloud parameterization schemes used in different models.Cloud Feedback Model Intercomparison Project(CFMIP)observation simulator package(COSP)is a great tool to accurately assess the performance of climate models on simulating clouds.More intuitive and credible evaluation results can be obtained based on the COSP model output.In the future,with the release of more COSP output of CMIP6 models,it is expected that those inter-model spreads and the model-observation biases can be substantially reduced.Longer term active satellite observations are also necessary to evaluate models’cloud simulations and to further explore the role of clouds in the rapid Arctic climate changes.

Tunable terahertz radiation from arbitrary profile dielectric grating coated with graphene excited by an electron beam

In this paper, the enhanced terahertz radiation transformed from surface plasmon polaritons, excited by a uniformly moving electron bunch, in a structure consisting of a monolayer graphene supported on a dielectric grating with arbitrary profile is investigated. The results show that the grating profile has significant influence on the dispersion curves and radiation characteristics including radiation frequency and intensity. The dependence of dispersion and radiation characteristics on the grating shape for both the symmetric and asymmetric gratings is studied in detail. Moreover, we find that, for an asymmetric grating with certain profile, there exist two different diffraction types, and one of the two types can provide higher radiation intensity comparing to the other one. These results will definitely facilitate the practical application in developing a room-temperature, tunable, coherent and miniature terahertz radiation source.

Teleconnected Influence of the Boreal Winter Antarctic Oscillation on the Somali Jet： Bridging Role of Sea Surface Temperature in Southern High and Middle Latitudes

The teleconnection impact of the boreal winter Antarctic Oscillation（AAO） on the Somali Jet（SMJ） intensity in the following spring and summer is examined in this paper.The variability of the boreal winter AAO is positively related to the SMJ intensity in both spring and summer.The analyses show that the SST in southern high and middle latitudes seems to serve as a bridge linking these two systems.When the AAO is in strong positive phase,SST over the Southern Ocean cools in the high latitudes and warms in the middle latitudes,which persists into summer;however,the variability of SST in southern high and middle latitudes is also closely correlated to SMJ intensity.A possible mechanism that links SST variability with the AAO-SMJ relationship is also discussed.The AAO in boreal winter produces an SST anomaly pattern in southern high and middle latitudes through the air-sea coupling.This AAOrelated SST anomaly pattern modulates the local Ferrel cell anomaly in summer,followed by the regional Hadley cell anomaly in tropics.The anomalous vertical motion in tropics then changes the land-sea thermal contrast between the tropical Indian Ocean and the Asian continent through the variability of low cloud cover and downward surface longwave radiation flux.Finally,the land-sea thermal contrast anomaly between the tropical Indian Ocean and the Asian continent changes the SMJ intensity.The results from Community Atmosphere Model experiments forced by the SST anomaly in southern high and middle latitudes also confirm this diagnostic physical process to some extent.

Nonlinear Thermal Buoyancy on Ferromagnetic Liquid Stream Over a Radiated Elastic Surface with Non Fourier Heat Flux

The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat flux.In most of the existing studies,the heat flux is considered as constant,but whereas we incorporated the non-Fourier flux to get the exact performance of the flow.Also,we excluded the PWT and PHF cases to control the boundary layer of the flow.The governing equations related to our contemplate are changed into non-linear ordinary differential equations(ODE’s)by utilizing appropriate similarity changes,which are at the point enlightened by Runge–Kutta based shooting approach.The equations are broken down concerning boundary conditions and to be explained prescribed wall temperature(PWT)and prescribed heat flux(PHF)cases.The impacts of diverse non-dimensional physical parameters on velocity and temperature profiles are laid out graphically.Also,the assortment of skin friction and local Nusselt number for both PWT and PHF cases for various assessments of non-dimensional parameters have been sorted out.Towards the wrap-up of the examination,we suspect that the friction factor coefficient is higher in the PWT case compared to the PHF case.This result helps to conclude that the flux conditions are useful for cooling applications.

Aperture-Shared Radiation Surface:A Promising Technique for Multifunctional Antenna Array Development

In the development of a multifunctional and multi-standard analog frontend module in emerging and future wireless systems,multifunction antenna array is an indispensable component.To this end,the aperture-shared technique has come of age,and demonstrated significant advantages in the cost-effective design of efficient,compact,multiband,multibeam,and polarization-diversified antenna arrays,particularly with high frequency ratios.In this paper,various antenna topologies and surface architectures based on this technique,which have been proposed and developed thus far for a wide variety of applications,are reviewed,examined,and categorized to highlight the nature of electromagnetic aperture-shared schemes and merits.Finally,we briefly discuss future research directions in this context for multifunction millimeter-wave and terahertz wireless systems development.