Inter-comparisons of thermodynamic sea-ice modeling results using various parameterizations of radiative flux

Radiative fluxes are of primary importance in the energy and mass balance of the sea-ice cover. Various parameterizations of the radiative fluxes are studied in a thermodynamic sea-ice model. Model outputs of the surface radiative and heat fluxes and mass balance are compared with observations. The contribution of short-wave radiation is limited to a long part of winter. Therefore, simple schemes are often sufficient. Errors in estimations of the short-wave radiation are due mainly to cloud effects and occasionally to multi-reflection between surface and ice crystals in the air. The long-wave radiation plays an important role in the ice surface heat and mass balance during most part of a winter. The effect of clouds on the accuracy of the simple radiative schemes is critical, which needs further attention. In general, the accuracy of an ice model depends on that of the radiative fluxes.

A Mixed Radiative-Convective Technique for the Calibration of Heat Flux Sensors in Hypersonic Flow

The ability to measure the very high heat fluxes that typically occur during the hypersonic re-entry phase of space vehicles is generally considered a subject of great importance in the aerospace field.Most of the sensors used for these measurements need to be checked periodically and re-calibrated accordingly.Another bottleneck relates to the need to procure thermal sources that are able to generate reliable reference heat fluxes in the range between 100 and 1000 kW/m^(2)(as order of magnitude).In the present study,a method is presented by which,starting from a calibration system with a capacity of approximately 500 kW/m^(2) only,heat fluxes in the range of interest for hypersonic applications are generated.The related procedure takes advantage of established standards for the characterization of a radiative heat flux.It also builds on the hybrid radiative-convective nature of typical hypersonic heat fluxes and the yet poorly explored possibility to use convective sources of heat to produce high-intensity fluxes.The reliability of such a strategy has been tested using a high enthalpy supersonic flow facility relying on an electric arc-heater and pure Nitrogen as work gas.Stagnation-point heat fluxes have been successfully measured(with reasonable accuracy)in the range between 600 and 1500 kW/m^(2) for values of the centerline enthalpy spanning the interval from to 6 to 24 MJ/kg.

Theoretical Analysis of Retrieving Atmospheric Columnar Mie Optical Depth from Downward Total Solar Radiative Flux

In this paper, the principle to determine the atmospheric columnar Mie optical depth from downward total solar radiative flux is theoretically studied, and the effect on Mie optical depth solution of the errors in surface albedo, sin-gle scattering albedo, asymmetrical factor of scattering phase function, instrumental constant and the approximate expression of diffusion flux is analy/ed, and then a method for determining surface albedo in shorter wavelength range is presented.

Spatial Distributions of Atmospheric Radiative Fluxes and Heating Rates over China during Summer

The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.

Intercomparison of Surface Radiative Fluxes in the Arctic Ocean

Recent satellite data analysis has provided improved data sets relevant to the surface energy budget in the Arctic Ocean. In this paper, surface radiation properties in the Arctic Ocean obtained from the Surface Radiation Budget（SRB3.0） and the International Satellite Cloud Climatology Project（ISCCP-FD） during 1984– 2007 are analyzed and compared. Our analysis suggests that these datasets show encouraging agreement in basin-wide averaged seasonal cycle and spatial distribution of surface albedo; net surface shortwave and all-wave radiative fluxes; and shortwave, longwave, and all-wave cloud radiative forcings. However, a systematic large discrepancy is detected for the net surface longwave radiative flux between the two data sets at a magnitude of ~ 23 W m–2, which is primarily attributed to significant differences in surface temperature, particularly from April to June. Moreover, the largest difference in surface shortwave and all-wave cloud radiative forcings between the two data sets is apparent in early June at a magnitude of 30 W m–2.

Calculation of radiative heat flux on irregular boundaries in participating media

Radiative heat flux at wall boundaries is important for its thermal design.Numerical methods based on structured grids are becoming trendy due to their simplicity and efficiency.Existing radiative transfer equation solvers produce oscillating radiative heat flux at the irregular boundary if they are based on structured grids.Reverse Monte Carlo method and analytical discrete ordinates method are adopted to calculate the radiative heat flux at complex boundaries.The results show that the reverse Monte Carlo method can generate a smooth radiative heat flux profile and it is smoother with larger energy bundles.The results from the analytical discrete ordinates method show that the fluctuations are due to the ray effect.For the total or the mean radiative heat flux,the results from the analytical discrete ordinates method are very close to those from the reverse Monte Carlo method.

Chemically reactive and radiative von Kármán swirling flow due to a rotating disk

A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temperature at the surface, a simple isothermal model of homogeneous-heterogeneous reactions is employed. The impact of nonlinear thermal radiative heat flux on thermal transport features is studied. The transformed nonlinear system of ordinary differential equations is solved numerically with an efficient method, namely, the Runge-Kutta-Felberg fourth-order and fifth-order(RKF45)integration scheme using the MAPLE software. Achieved results are validated with previous studies in an excellent way. Major outcomes reveal that the magnetic flux reduces the velocity components in the radial, angular, and axial directions, and enhances the fluid temperature. Also, the presence of radiative heat flux is to raise the temperature of fluid. Further, the strength of homogeneous-heterogeneous reactions is useful to diminish the concentration of reaction.

Radiative Divertor Plasma Behavior in L- and H-Mode Discharges with Argon Injection in EAST

Introducing strong radiative impurities as an important way to mitigate the peak heat load will be employed in EAST for high power long pulse experiments were explored under both low （L） and the first time in EAST, with the injection of argon into divertor plasmas has been considered at the divertor target plate for ITER, and operations. To this end, radiative divertor high （H） - mode confinement regimes, for and its mixture （25% Ar in D2）. The Ar injection greatly reduced particle and heat fluxes to the divertor in L-mode discharges, achieving nearly complete detached divertor plasma regimes for both single null （SN） and double null （DN） configurations, without increasing the core impurity content. In particular, the peak heat flux was reduced by a factor of ~6~ significantly reducing the intrinsic in-out divertor asymmetry for DN, as seen by both the new infra-red camera and the Langmuir probes at the divertor target. Promising results have also been obtained in the H-modes with argon seeding, demonstrating a significant increase in the frequency and decrease in the amplitude of the edge localized modes （ELMs）, thus reducing both particle and heat loads caused by the ELMs. This will be further explored in the next experimental campaign with increasing heating power for long pulse operations.

Calculating the Climatology and Anomalies of Surface Cloud Radiative Effect Using Cloud Property Histograms and Cloud Radiative Kernels

Cloud radiative kernels(CRK)built with radiative transfer models have been widely used to analyze the cloud radiative effect on top of atmosphere(TOA)fluxes,and it is expected that the CRKs would also be useful in the analyses of surface radiative fluxes,which determines the regional surface temperature change and variability.In this study,CRKs at the surface and TOA were built using the Rapid Radiative Transfer Model(RRTM).Longwave cloud radiative effect(CRE)at the surface is primarily driven by cloud base properties,while TOA CRE is primarily decided by cloud top properties.For this reason,the standard version of surface CRK is a function of latitude,longitude,month,cloud optical thickness(τ)and cloud base pressure(CBP),and the TOA CRK is a function of latitude,longitude,month,τand cloud top pressure(CTP).Considering that the cloud property histograms provided by climate models are functions of CTP instead of CBP at present,the surface CRKs on CBP-τhistograms were converted to CTP-τfields using the statistical relationship between CTP,CBP andτobtained from collocated CloudSat and MODIS observations.For both climate model outputs and satellites observations,the climatology of surface CRE and cloud-induced surface radiative anomalies calculated with the surface CRKs and cloud property histograms are well correlated with those calculated from surface radiative fluxes.The cloud-induced surface radiative anomalies reproduced by surface CRKs and MODIS cloud property histograms are not affected by spurious trends that appear in Clouds and the Earth's Radiant Energy System(CERES)surface irradiances products.

Shortwave Cloud and Aerosol Radiative Forcings and Their Effects on the Vertical Local Heating/Cooling Rates

An analysis of atmospheric SW-radiative forcing and local heating/cooling rate is made using a one year temporal and vertical profiles of aerosol and cloud over Yaoundé (11.51°E, 3.83°N). It appears that the direct influence of aerosols on the surface compared to the TOA can be 3 times larger. Annual mean value obtained at 559 mb altitude is +27.74 W/m2 with range from 0 to +43 W/m2. At 904 mb, we obtained an annual mean of ﹣46.22 W/m2 with range from ﹣65 to ﹣9 W/m2. Frequency distribution indicates that more than 95% of ARF are between +10 and +70 W/m2 at 559 mb (upper limit of UL), and more than 85% of ARF are between ﹣70 and ﹣10 W/m2 at 904 mb (upper limit of PBL). This sign change is explained by the fact that the backscattering peaks at the upper limit of the aerosol PBL layer. The maximum CRF is noted at TOA where it reaches ﹣600 W/m2 based on the time interval and the structure of clouds. The highest values occur between 11.50 and 13.50 LST. Clouds lead to a general heating of the entire atmospheric column with a much greater effect near the surface. Aerosols effect on the heating rate profile show strong cooling during the day for the lower atmosphere, with slight heating at the upper atmosphere. This cooling contribution generally increases from the surface and peacks at the upper boundary of aerosol layer where reflectivity is the most important. Depending on the moment of the day, average heating effect of clouds peacks at surface or within the middle troposphere due to the absorption by clouds particles. Vertical profiles deeply evolve exhibiting differences that exceed ﹣3 K/day according to altitude from one hour to another during a given mean solar day.

Coastal buoy observation of air-sea net heat flux in the East China Sea in summer 2020

The full fluxes and associated air-sea variables based on three months of operational buoy observations in the East China Sea(ECS)in summer 2020 were analyzed for the first time.The surface net heat flux(Q_(net))was positive(139.7±77.7 W/m^(2))and was dominated by the combined eff ects of solar shortwave radiation(SW)and latent heat fluxes(LH).The mean heat flux components of 4 reanalysis datasets(NCEP2,MERRA-2,CFSR,and ERA5)and buoy data were compared to assess the mean ability of the modeling/reanalysis simulation.Among the four components of air-sea flux,SW was the best simulated,while LH was the worst simulated.The longwave radiation(LW)and LH values from reanalysis were higher than those from buoy data,especially LH.The high LH resulted in low Q_(net).Furthermore,the 4 reanalysis datasets were compared with the buoy dataset.Among all flux products,the difference in radiation flux was the smallest,while that in the turbulent flux was the greatest.The observed variables related to turbulent flux were analyzed to help determine the cause of the flux discrepancies.High wind speeds were the main cause of this difference.Using the variables provided by the reanalysis data and the same bulk formulas of the Coupled Ocean-Atmospheric Response Experiment(COARE 3.0),we found that the recalculated sensible heat flux(SH)and LH were closer to the observed heat fluxes than the direct model outputs.The signifi cant diff erences between these methods could account for the discrepancies among diff erent data.Among all air-sea flux products,the air-sea flux in ERA5 was closer to the in-situ observations than the other products.The comparison results of reanalysis data provide an important reference for more accurate studies of the summer heat flux in the ECS at the synoptic and climatic scales.

Temperature and Heat Flux Distributions through Single and Double Window Glazing Nongray Calculation

Accurate prediction of thermal radiation by applying rigorous model for the radiative heat transfer combined with the conduction and the convection has been performed for a single and double window glazing subjected to solar and thermal irradiation. The glass window is analysed as a non-gray plane-parallel medium disctritized to thin layer as-suming the glass material as participating media in one-dimensional case, using the Radiation Element Method by Ray Emission Model (REM2). The model allows the calculation of the steady-state heat flux and the temperature distribution within the glass cover. The spectral dependence of the relevant radiation properties of glass (i.e. specular reflectivity, refraction angle and absorption coefficient) is taken into account. Both solar and thermal incident irradiations are applied at the boundary surfaces using the spectral solar model proposed by Bird and Riordan. The optical constant of a commercial clear glass material have been used. The calculation has been performed during winter period and the effect of the thickness of the glass for a single glazing and of the air layer between the two panels for double glazing has been studied. The result shows that increasing the air layer, the steady heat flux decreases and the temperature distribution within the glass changes.

Radiative entransy flux in enclosures with non-isothermal or non-grey,opaque,diffuse surfaces and its application

The spectral radiative entransy flux and the total radiative entransy flux are defined for the steady radiative heat transfer processes in enclosures composed of non-isothermal or non-grey, opaque, diffuse surfaces. Based on the definitions, the radiative entransy flux balance equation and the radiative entransy dissipation functions are introduced under spectral and total wavelength condition. Furthermore, the minimum principle of radiative entransy loss, the extreme principle of radiative entransy dissipation and the minimum principle of radiative thermal resistance are developed. The minimum prirlciple of radiative en- transy loss shows that the potential and the net radiative heat flux distribution which meet the control equations and the boundary conditions would make the radiative entransy loss minimum if the net radiative heat flux or the potential distribution of the radiative heat transfer system is given. The extreme principle of radiative entransy dissipation indicates that the minimum radiative entransy dissipation leads to the minimum average potential difference for the prescribed total radiative heat exchange and the maximum radiative entransy dissipation leads to the maximum radiative heat exchange for the prescribed average potential difference. Moreover, the minimum principle of radiative thermal resistance tells us that the aforementioned extreme values of radiative entransy dissipation both correspond to the minimum value of radiative thermal resistance. Application examples are given for the extreme principle of spectral radiative entransy dissipation and the minimum principle of spectral radiative thermal resistance, and the principles are proved to be applicable.

Unsteady MHD Casson Nanofluid Flow Past an Exponentially Accelerated Vertical Plate:An Analytical Strategy

In this study,the characteristics of heat transfer on an unsteady magnetohydrodynamic(MHD)Casson nanofluid over an exponentially accelerated vertical porous plate with rotating effects were investigated.The flow was driven by the combined effects of the magnetic field,heat radiation,heat source/sink and chemical reaction.Copper oxide(CuO)and titanium oxide(TiO2)are acknowledged as nanoparticle materials.The nondimensional governing equations were subjected to the Laplace transformation technique to derive closed-form solutions.Graphical representations are provided to analyze how changes in physical parameters,such as the magnetic field,heat radiation,heat source/sink and chemical reaction,affect the velocity,temperature and concentration profiles.The computed values of skin friction,heat and mass transfer rates at the surface were tabulated for various sets of input parameters.It is perceived that there is a drop in temperature due to the rise in the heat source/sink and the Prandtl number.It should be noted that a boost in the thermal radiation parameter prompts an increase in temperature.An increase in the Prandtl number,heat source/sink parameter,time and a decrease in the thermal radiation parameter result in an increase in theNusselt number.The computed values of the skin friction,heat andmass transfer rates at the surface were tabulated for various values of the flow parameters.The present results were compared with those of previously published studies andwere found to be in excellent agreement.This research has practical applications in areas such as drug delivery,thermal medicine and cancer treatment.

Effectiveness of radiative heat flux in MHD flow of Jeffrey-nanofluid subject to Brownian and thermophoresis diffusions

Our interest here in this investigation is to explore the thermophoresis and Brownian motion characteristics in flow induced by stretched surface.Electrically conducted Jeffrey material formulates the flow equation.Linear forms of stretching and free stream velocities are imposed.Nonlinear radiation and convective heating processes describe the phenomenon of heat transfer.Passive controls of nanoparticles are considered on the boundary.The compatible transformations produce the strong nonlinear differential systems.The problems are computed analytically utilizing HAM.Converge nee domain is detennined and major results are concluded for different parameters involved.Heat transfer rate and drag force are also explained for various physical variables.Our analysis reveals that heat transfer rate augments via larger radiation parameter and Biot number.Moreover larger Brownian motion and thermophoresis parameters have opposite characteristics on concentration field.

南海温跃层基本特征及一维预报模式

根据现有1907—1990年南海大面调查资料,按1°×1°网格进行逐月的标准水层的温度统计。在此基础上采用3次样条函数的插值方法计算出整个南海温跃层的深度、厚度和强度并予以相应分析。分析表明,南海温跃层主要分为两种类型:第一类为辐射型,主要分布在南海北部的陆架区内,季节变化显著;第二类为不同水体叠置型,主要分布在广大深水区,它长年存在,季节变化较小。一种温跃层的一维积分预报模式,该模式是基于忽略热平流作用和水平热扩散的前提下,从局部热平衡方程出发,建立了受海面热收支及风混合作用下求解温度垂直分布及温跃层的时空变化。在南海北部水深约300m处进行了单站温跃层后报,结果表明,温跃层的深度、厚度和强度的相对误差均在30％以下。

广州地区光化辐射通量与辐照度的特征

应用NCARTUV辐射模式与地表实际观测分析了理论上广州地区地表可获得的最强光化辐射通量、辐照度及其波谱变化特征与月、日变化特征,计算与观测的差异用于评估气溶胶对紫外辐射通量的作用.结果表明,光化辐射通量与辐照度均具有正弦曲线的日变化特征,但光化辐射通量的正弦波形较辐照度的更为宽广,其辐射强度随太阳天顶角的增加下降幅度也更为缓慢;光化辐射中的总能量可见光谱区约占86%,紫外谱区仅占约14%;理论计算与实际观测表明,不同监测波段范围的紫外辐射表,虽然其标识均为监测UVA或UVB的辐射,但差异明显;广州地区的气溶胶污染显著影响紫外辐射通量.由于紫外辐射通量是影响对流层臭氧生产力的关键因子,有必要更加深入地认识广州地区气溶胶与紫外辐射通量的相互作用.

混合模拟方法分析三维封闭腔内辐射换热

１引言工程上对炉内三维辐射换热的计算已越来越重视，较为精确的计算方法是Ｈｏｔｔｅｌ的区域法［１，２］和ＭｏｎｔｅＣａｒｌｏ方法［３］，但两者都有一定的局限性而得不到广泛应用，原因如下：对区域法，由于计算区域间直接辐射交换面积时需求解多重积分，在计算时...

车辆热特征分析及红外热像模拟

给出了车辆热特征分析及红外热像模拟的方法，并以坦克为例，根据其自身结构特点及外界条件，建立了坦克车体三维瞬态温度场及整体辐射通量计算模型，运用色度学原理，根据数值计算结果。

矿尘气溶胶短波辐射效应的初步研究

在辐射传输模式CRM中引入粒径为0.5、1.0、2.0、4.0、8.0 m的5段矿尘气溶胶粒子,模拟计算气溶胶对短波辐射通量的影响。计算结果表明:气溶胶引起晴空短波净辐射通量减少;在分布有气溶胶的层内,粒子半径增大、光学厚度增大都会使短波净辐射通量减少;在气溶胶层以上,辐射通量的变化与具体的粒子半径有关。