A Theoretical Model for the Microwave Emissivity of Rough Sea Surfaces

When sea surface wavelengths are not larger than microwave wavelengths,the microwave emissivity of Gaussian rough sea surfaces can be investigated by applying effective media theory(EMT)of rough surfaces.For one-dimensional Gaussian sea surface,the microwave emissivity model is proposed by EMT,which regards the air-sea rough interface as a new effective medium of isotropic permittivity between the top layer of air and the bottom layer of seawater.The emissivity model is controlled by the root mean square deviation(RMSD)of the rough surface height and the correlation length of the rough surface.Results clearly show that the emissivity increases along with the RMSD increase if the latter is smaller than a critical value.Furthermore,excess emissivities and the brightness temperature increments for a wind-roughened sea surface can be estimated from those of flat surfaces by fitting the RMSD as a function of wind speed.Good agreements are obtained by comparing the results of our model with the satellite data at microwave frequencies of 1.4,6.8,18,21,and 37 GHz,respectively.Moreover,these findings imply that our method can be extended to retrieve the sea surface parameters,such as RMSD and the correlation length of the rough surface,from the satellite data.

Assessment and analysis of microwave emissivity and transmissivity of a deciduous forest towards the estimate of vegetation biomass

Forests play an important role in the global carbon cycle and have a potential impact on global climatic change.Monitoring forest biomass is of considerable importance in understanding the hydrological cycle.Because of the problem of dense forest cover,no reliable method with which to retrieve soil moisture in forest areas from the microwave emission signature has been established.All of these issues relate to the microwave emissivity and transmissivity characteristics of a forest.The microwave emission contribution received by a sensor above a forest canopy comes from both the soil surface and the vegetation layer.To analyze the relationship of forest biomass and forest emission and transmissivity,a high-order emission model,the matrix-doubling model,which consists of both soil and vegetation models,was developed and then validated for a young deciduous forest stand in a field experiment.To simulate the emissivity and transmissivity of a deciduous forest in the L and X bands using the matrix-doubling model,the parameters of components of deciduous trees when the leaf area index varies from 1 to10 were generated by an L-system and a forest growth model.The emissivity and transmissivity of a forest and the relationships of these parameters to forest biomass are presented and analyzed in this paper.Emissivity in the L band when the leaf area index is less than 6 and at viewing angles less than 40°,and transmissivity in the L band are the most sensitive parameters in deciduous forest biomass estimation.

Spatiotemporal Variations of Microwave Land Surface Emissivity(MLSE)over China Derived from Four-Year Recalibrated Fengyun 3B MWRI Data

Microwave Land Surface Emissivity(MLSE)over China under both clear and cloudy sky conditions was retrieved using measurements of recalibrated microwave brightness temperatures(Tbs)from Fengyun-3B Microwave Radiation Imager(FY-3B MWRI),combined with cloud properties derived from Himawari-8 Advanced Himawari Imager(AHI)observations.The contributions from cloud particles and atmospheric gases to the upwelling Tbs at the top of atmosphere were calculated and removed in radiative transfer.The MLSEs at horizontal polarizations at 10.65,18.7,and 36.5 GHz during 7 July 2015 to 30 June 2019 over China showed high values in the southeast vegetated area and low values in the northwest barren,or sparsely vegetated,area.The maximum values were found in the belt area of the Qinling-Taihang Mountains and the eastern edge of the Qinghai-Tibet Plateau,which is highly consistent with MLSEs derived from AMSR-E.It demonstrates that the measurements of FY-3B MWRI Tbs,including its calibration and validation,are reliable,and the retrieval algorithm developed in this study works well.Seasonal variations of MLSE in China are mainly driven by the combined effects of vegetation,rainfall,and snow cover.In tropical and southern forest regions,the seasonal variation of MLSE is small due to the enhancement from vegetation and the suppression from rainfall.In the boreal area,snow causes a significant decrease of MLSE at 36.5 GHz in winter.Meanwhile,the MLSE at lower frequencies experiences less suppression.In the desert region in Xinjiang,increases of MLSEs at all frequencies are observed with increasing snow cover.

Retrieval of Microwave Surface Emissivities at TMI Frequencies in Shouxian

Using a microwave radiative transfer model, atmospheric sounding profiles, satellite brightness temperatures, and some surface observed measurements under cloud-free conditions, surface emissivities at the frequencies of TRMM/TMI (Tropical Rainfall Measuring Mission Microwave Imager) at Shouxian in HUBEX (Huaihe River Basin Energy and Water Cycle Experiment) are retrieved. Compared to the microwave surface emissivities with changing conditions of the surface, it is found that the microwave emissivities have some sensitive variability with the conditions of the surface, and the variability is reasonable. In the calculation, the surface air temperatures are assumed to equal the surface skin temperatures, and only the emissivity at Shouxian is calculated; the calculation of the emissivities over the region of HUBEX needs more measurements.

Improving microwave brightness temperature predictions based on Bayesian model averaging ensemble approach

The choices of the parameterizations for each component in a microwave emission model have significant effects on the quality of brightness temperature （Tb） sim- ulation. How to reduce the uncertainty in the Tb simulation is investigated by adopting a statistical post-processing procedure with the Bayesian model averaging （BMA） ensemble approach. The simulations by the community microwave emission model （CMEM） cou- pled with the community land model version 4.5 （CLM4.5） over China's Mainland are con- ducted by the 24 configurations from four vegetation opacity parameterizations （VOPs）, three soil dielectric constant parameterizations （SDCPs）, and two soil roughness param- eterizations （SRPs）. Compared with the simple arithmetical averaging （SAA） method, the BMA reconstructions have a higher spatial correlation coefficient （larger than 0.99） than the C-band satellite observations of the advanced microwave scanning radiometer on the Earth observing system （AMSR-E） at the vertical polarization. Moreover, the BMA product performs the best among the ensemble members for all vegetation classes, with a mean root-mean-square difference （RMSD） of 4 K and a temporal correlation coefficient of 0.64.

Evaluation of the Community Microwave Emission Model Coupled with the Community Land Model over East Asia

The Community Microwave Emission Model (CMEM) developed by the European Centre for Me-dium-Range Weather Forecasts (ECMWF) can provide a link between surface states and satellite observations and simulate the passive microwave brightness temperature of the surface at low frequencies (from 1 GHz to 20 GHz).This study evaluated the performance of the CMEM cou-pled with the Community Land Model (CLM) (CMEM-CLM) using C-band (6.9 GHz) microwave brightness temperatures from the Advanced Microwave Scanning Radiometer on Earth Observing System (AMSR-E) over East Asia.Preliminary results support the argument that the simulated brightness temperatures of CMEM-CLM from July 2005 to June 2010 are comparable to AMSR-E observational data.CMEM-CLM performed better for vertical polarization,for which the root mean square error was approximately 15 K,compared to over 30 K for horizontal polarization.An evaluation performed over seven sub-regions in China indicated that CMEM-CLM was able to capture the temporal evolution of C-band brightness temperatures well,and the best correlation with AMSR-E appeared over western Northwest China (over 0.9 for vertical polarization).However,larger biases were found over southern North China and the middle and lower reaches of the Yangtze River.

A Study on the Determination of Copper by Microwave Induced Plasma Atomic Emission Spectrometry (MIP-AES)

The determination of copper by MIP-AES was investigated in detail. Aqueous samples were introduced from an ultrasonic nebulizer and the solvent was removed by a desolvation device before introduction of the aerosol into the MIP. The desolvation system consisted of a condenser associated with a concentrated H2SO4 absorption cell. Various experimental conditions and interferences from easily ionised elements (EIEs) were also studied and some practical samples were analyzed.

Estimation of the Power of the Anomalous Microwave Emission

Context and Background: The product of the electromagnetic (EM) wave’s power P times its period τ, i.e. Pτ, is the amount of energy conserved in EM wave’s absorption in matter. Whether Pτ is the amount of energy conserved in the emission of EM waves from matter is not assessed. Motivation: In this research, we perform a computational study to explore the ability of Pτ to represent the amount of energy conserved in EM wave’s emission from matter. Hypothesis: Since the magnitude of the power P of emitted EM waves computed through Larmor’s formula for a rotating dipole is excessively small, we alternatively hypothesize that Pτ and the law of conservation of energy can lead to a realistic estimation of P. Methods: We estimate the power PAME of the anomalous microwave emission (AME), a well-characterized radiation generated in the interstellar medium (ISM) by spinning dust grains, and one possible source of contamination of the cosmic microwave background (CMB). For our estimation of PAME, we assume the AME to be generated in a molecular cloud mostly populated by spinning silicate nanoparticles (SSNs) or polycyclic aromatic hydrocarbon (PAH) spinning dust grains. Indeed, SSNs and PAHs are listed among the most probable sources of AME, and their characteristics are well-known. We discriminate between realistic and non-realistic values of PAME based upon the magnitude of two parameters that depend on PAME: the significant distance z, and the time of photon production T. The parameter z is the space interval from the spinning dust grain within which the spinning dust grain’s electric field is effective. Results: Using the information available for AME, SSNs and PAHs, we estimate the power PAME using both Larmor’s formula and Pτ. We compare and comment the results obtained for z and T. Conclusions: Our study highlights the effectiveness of Pτ over Larmor’s formula in providing a realistic value of PAME. This finding might have consequences in quantum technology of single photon detection and production.

The Main Results and the Perspectives in the Researches at SSRT

In this report briefly presented the contemporary state of the experimental base of Radio Astrophysical Observatory(RAO)of the Institute of Solar-Terrestrial Physics(ISTP),the methodology of radioheliographic monitoring of the solar corona,the SSRT database,the RAO Web-pages,factors limiting the effective use of SSRT.Here are formulated the original results of the basic directions of the solar activity researches and the problems solutions on SSRT:(1)active regions at various development stages,morphology,modeling,signs of energy accumulation and flares buildup,forecast of powerful flares;(2)scenario,topology and the fine temporal picture of flares development,signs of primary energy release,radio emission mechanisms,scatter effects of radio emission in turbulent corona,energetic particles fluxes;(3)filaments;(4)CME with the localization of their initiation at the solar disk background,development scenario of filament activation+CME+flare;(5)coronal holes,and(6)bright coronal points.

LABORATORY STUDY ON MICROWAVE REMOTE SENSING OF GROUND TRUTH

In order to improve the interpretation of the earth system microwave remote sensing, the research of microwave spectrum characteristics of the ground truth (earth objects) was carried out in laboratory. A laboratory for microwave remote sensing of the earth objects has been constructed to improve the remote sensing level, the laboratory consists of four parts: the measuring system of dielectric constants, the microwave emissivity meter, the microwave reflectometer and the microwave remote sensing simulation experiment in field. In this paper, the principle of measurement, the correction of near field process, the structure of instrument, the calibration method and the measurement of the earth substances, including soil, water and oil, are discussed. The labora- tory may supply the condition for measuring the parameters of thc earth substance remote sensing and help to interpret the remote sensing data.

A method to estimate crop effects at higher frequencies by modeling and microwave radiometric data

To use the 0th-order τ-ω model to retrieve soil moisture from radiometric data at frequencies higher than the C band, the characteristics of the effective single scattering albedo ω and the opacity rof vegetation must be studied. In this paper, the co and r values of corn for the C, X, and Ku bands were retrieved by matching the simulations of a high-order matrix-doubling model to the τ-ω model. First, the brightness temperature of the matrix-doubling was validated by a truck-mounted radiometer in a field experiment, where the vegetation emission contributions were validated with aluminum foil to mask the soil emission. Then an emissivity database of corn fields for different growing seasons was established for a variety of soil conditions. With the transmissivity of corn determined from the database, the effective single scattering albedos of corn for different heights at the C, X, and Ku bands and at a 55° viewing angle were derived. To verify the accuracy of the derived co and τ values, we used SMEX02/PSR aircraft data and the Qp model to retrieve the soil moisture; the RMSE between the retrieval and the measurements was 4.76% at the C band and 5.36% at the X band.

Influence of Surface Temperature and Emissivity on AMSU-A Assimilation over Land

AMSU-A （Advanced Microwave Sounding Unit-A） measurements for channels that are sensitive to the surface over land have not been widely assimilated into numerical weather prediction （NWP） models due to complicated land surface features. In this paper, the impact of AMSU-A assimilation over land in Southwest Asia is investigated with the Weather Research and Forecasting （WRF） model. Four radiance assimilation experiments with different land-surface schemes are designed, then compared and verified against radiosonde observations and global analyses. Besides the surface emissivity calculated from the emissivity model and surface temperature from the background field in current WRF variational data assimilation （WRF-VAR） system, the surface parameters from the operational Microwave Surface and Precipitation Products System （MSPPS） are introduced to understand the influence of surface parameters on AMSU-A assimilation over land. The sensitivity of simulated brightness temperatures to different surface configurations shows that using MSPPS surface alternatives significantly improves the simulation with reduced root mean square error （RMSE） and allows more observations to be assimilated. Verifications of 24-h temperature forecasts from experiments against radiosonde observations and National Centers for Environmental Prediction （NCEP） global analyses show that the experiments using MSPPS surface alternatives generate positive impact on forecast temperatures at lower atmospheric layers, especially at 850 hPa. The spatial distribution of RMSE for forecast temperature validation indicates that the experiments using MSPPS surface temperature obviously improve forecast temperatures in the mountain areas. The preliminary study indicates that using proper surface temperature is important when assimilating lower sounding channels of AMSU-A over land.

Influence of(FeO+Ti O_2) abundance on the microwave thermal emissions of lunar regolith

One of the essential controls on the microwave thermal emissions(MTE) of the lunar regolith is the abundance of Fe O and TiO_2, known as the(Fe O+Ti O_2) abundance(FTA). In this paper, a radiative transfer simulation is employed first to study the change in the brightness temperature(T_B) with FTA under a range of frequencies and surface temperatures. Then, we analyze the influence of FTA on the MTE of the lunar regolith using microwave sounder(CELMS) data from the Chang'E-2 lunar orbiter, Clementine UV-VIS data, and lunar samples recovered from the Apollo and Surveyor projects. We conclude that:(1) FTA strongly influences the MTE of the lunar regolith, but it is not the decisive control, and(2) FTA decreases slightly with depth. This research plays an essential role in appropriately inverting CELMS data to obtain lunar regolith parameters.