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Features of construction of mm-band and cm-band radiometers based on satellite low noise blocks (SLNB) are examined. The characteristics of the developed and constructed radiometer layout are presented. The experimental results are shown and compared with the published data. The possibility of using SLNB as an HF intermediate amplifier of mm-band radiometers and two-bandwidth radiometers is examined. A conclusion about receiving apparatus has been made.

Abstract The current thermoelectric solar tower plants demand the measure of high solar irradiance on the receiver. Its measure would facilitate the operation of the plant and would contribute to a greater receiver security. Currently, solar tower plants do not have a flux measurement system in their receiver as it is not considered in their design. The inclusion of the flux measurement system in its design phase would facilitate its incorporation and correct operation. Instead, infrared temperature measurement systems are used to infer the irradiance on the receiver. This procedure is not suitable since the delay between the irradiance and the temperature in the receiver can reach a few minutes depending on the materials, the transfer fluid, the operating conditions and the meteorological variables. Traditional flux measurement methods, used during the evaluation of small solar receiver prototypes, turn to moving parts that do not extrapolate to large receivers of commercial solar tower plants due to scaling problems. On the other hand, the use of mobile elements, which interact with the concentrated solar radiation directed towards the receiver, would negatively affect the daily operation of the plant. This work presents a simple method that allows characterizing a large target and quantifying its degree of homogeneity and diffusivity. With favourable information about receiver diffusivity, a way of proceeding to measure directly high solar irradiance on the surface of the receivers of solar tower plants without including moving parts is presented. This measurement system would consist of a digital camera and a radiometer. Highlights • Procedure to measure directly high solar irradiance on the receiver surface. • This measurement system consists of a digital camera and a radiometer. • Characterization of a large target and quantification of its degree of diffusivity. [ABSTRACT FROM AUTHOR]

Temporal and spatial variation of sea ice type in the Arctic is an indicator of regional and global change. Arctic sea ice can be classified into two major categories: multiyear ice (MYI) and first-year ice. In this paper, classification method based on machine learning is established and applied to produce daily sea ice classification data set during the winter (November–April) from 2002 to 2017 using active microwave data from QuikSCAT and Advanced Scatterometer as well as passive microwave data from Advanced Microwave Scanning Radiometer for EOS, Special Sensor Microwave Imager/Sounder, and Advanced Microwave Scanning Radiometer 2 radiometer. First, the open water area is flagged out using brightness temperature (Tb) from the passive microwave sensor. Then, K-means algorithm is applied to identify the clusters of the two ice types in the Tb/backscatter parameter space and finally assign pixels to each class. Two optimization methods based on the movement of MYI and marginal ice zone are used to correct the misclassification of MYI. The results have shown a decrease of MYI in winter from 2002 to 2017, especially in 2008 and 2013 with a remarkable recovery in 2014. The classifications are consistent with results by visual interpretation from synthetic aperture radar images in the Canadian Arctic Archipelago with overall classification accuracy over 93%. Comparison with classifications from previous studies and products shows that our method could reflect more differences in MYI declining trend interannually and less anomalous fluctuations in certain years. [ABSTRACT FROM AUTHOR]

A new multilayer (ML) cloud detection algorithm based on three shortwave infrared (SWIR) and two longwave infrared (LWIR) channels is developed and applied to the Visible Infrared Imager Radiometer Suite (VIIRS) onboard the Suomi-NPP satellite. The algorithm identifies ML clouds, i.e., ice clouds overlying water clouds, based on satellite multispectral observations in the 1.38, 1.6, 2.25, 8.5, and 11 μm channels. We perform synthetic radiative transfer simulations to understand the sensitivities of the aforementioned channels on ML and single-layer (SL) clouds. Active CALIOP observations are used to evaluate the algorithm. Compared with the collocated CALIOP results, the algorithm can determine SL and ML clouds correctly with success rates of approximately 80% and 60%, respectively, and has similar performance to that of the current MODIS operational ML cloud detection algorithm. The misclassification of ML clouds as SL clouds is primarily caused by thin ice clouds that are practically undetectable using LWIR tests. Furthermore, the algorithm is extended to analyze data from radiometers onboard the geostationary Himawari-8 and FengYun-4A satellites, and results similar to those of VIIRS are obtained. • A new algorithm for multilayer cloud detection is developed for VIIRS radiometer. • Accurate radiative transfer is performed for model understanding and development. • The model is evaluated using collocated MODIS and CALIOP observations. • It is extended for multilayer cloud detection of two geostationary radiometers. [ABSTRACT FROM AUTHOR]

A next-generation real-aperture spaceborne radiometer system for high-quality ocean measurements is discussed. Instead of illuminating the antenna reflector by a classical feed array of horn antennas in a one-feed-per-beam configuration, a multi-feed-per-beam configuration is chosen. Each antenna beam is thus created by adding the outputs from many small antenna elements in the feed array, thus providing an antenna beam of unsurpassed quality. This solves the classical polarization purity and land/sea contamination issues. The concept requires many microwave receivers and fast analog-to-digital converters as well as fast digital signal processing onboard the satellite. This is discussed, and resource budgets, especially concerning power, are provided. [ABSTRACT FROM AUTHOR]

Active and passive microwave signals over land co-vary depending on their shared scattering and emission characteristics by soil and vegetation media. Estimates of this covariation can be used beneficially to downscale coarse-resolution brightness temperatures with high-resolution backscatter for enhanced-resolution Earth observations. In this study, a forward model of covariation for vegetated soil is derived by combining two well-established models of active and passive microwave interactions. The covariation model is inverted to obtain a single-pass observation-driven estimation of active-passive microwave covariation (β) based on multi-channel radiometer and Synthetic Aperture Radar (SAR) scenes. A key feature of the estimation approach is that it is applicable to co-located spatial data scenes and does not rely on temporal information. We present applications of the estimation with combinations of SMAP (L-band) radiometry and both SMAP (L-band) and multi-angular Sentinel-1 (C-band) backscatter data. We first show that for the period of available SMAP L-band radiometer and radar data, the estimation approach for β , introduced in this study, yields similar results as the statistical time-series approach originally designed for SMAP. The new single-pass approach also allows estimation of active-passive covariation where the statistical approach cannot be applied because dynamic range of brightness temperature and backscatter are too limited to allow regression. We then apply the developed estimation method to SMAP L-band radiometer and multi-angular Sentinel-1 C-band SAR data. Here, the study quantifies the effects of microwave frequency and look-angles on the covariation by applying the estimation globally and analyzing the results as a function of vegetation cover – a key determinant of the strength of the covariation. • A single-pass estimation of active-passive microwave covariation is established. • The approach allows estimation of covariation without the need for time series. • It is observation-driven and does not require site-specific calibration. • It enables global downscaling of SMAP radiometer with Sentinel-1 radar data. [ABSTRACT FROM AUTHOR]

A low noise, high gain, stable radiometer front-end is presented for non-invasive tissue thermometry using custom designed narrow band low noise amplifiers (LNAs) and band pass filter (BPF) with 1.3 GHz centre frequency and − 20 dB pass band of 332 MHz. The fabricated LNAs have >15 dB gain, unconditional gain stability and noise figure (NF) < 1.45 dB in the pass band. The maximum insertion loss of the BPF is <1 dB over 1.2-1.4 GHz with 50 dB suppression in the surrounding communication bands. The cascaded radiometer front-end has measured gain of 45-50 dB, NF < 1.75 dB in the pass band and > 30 dB suppression in the adjacent personal communication bands. The Allan deviation of the total power radiometer indicates long term system stability and presence of Gaussian thermal noise for integration time, . Radiometer measurements of a matched load at room temperature for indicate acceptably low influence of external electromagnetic interference (EMI) and system noise equivalent temperature of 145 K. The brightness temperature measured by the total power radiometer using a resonant slot antenna demonstrates the ability to detect a 0.3°C change in the test load temperature with better than 0.1°C accuracy. [ABSTRACT FROM AUTHOR]

Abstract Detection and mitigation of radio frequency interference (RFI) is one of the most crucial issues in microwave remote sensing measurements. This study analyzes the brightness temperature and RFI acquired by the soil moisture active passive (SMAP) satellite L-band radiometer over China and its offshore areas, revealing that the RFI distribution is uneven. In China, RFI is mainly concentrated in the urban agglomerations and their surrounding areas. Further, RFI and population density show strong positive correlation. A comparison of the radiometer antenna brightness temperature data and the data after RFI detection and mitigation shows that the volume of the detected RFI is ∼1.4 K and the standard deviation is 6.5. Under the influence of RFI, different bands and polarizations in the study area did not show significant differences. [ABSTRACT FROM AUTHOR]

Thermal Pyranometers are very important devices for evaluating the intensity of solar radiation under different climatic conditions. These devices utilize thermal radiation for comparison and determination of their efficiency. Because of this wide use associated with the development of new technologies, a simple and low-cost version of thermal pyranometer has been studied, designed and manufactured. A blackened aluminum disk is used as a hot junction, and the cold junction is exposed to ambient air. The two terminals are connected to a digital amplifier with output signal directed to an Arduino board. A device calibration was performed by comparing the results with a commercial photodiode sensor. Statistical analysis of the calibration data considering a 99% confidence level leads to an estimated standard error of 20.8 W/m². An analysis of its response time also estimated from a dynamic model. This model uses a numerical solution of the energy balance on heat exchange between the aluminum disc and the environment. The instrument response time based on the average of the estimates obtained from the dynamic model is about 1.5 minutes. Based on these studies it was concluded that the characteristics of the sensor are adequate for most solar energy tests and the final cost of US $ 60.00 is much lower than the large majority of such commercial devices. [ABSTRACT FROM AUTHOR]

Active and passive low-frequency microwave measurements from a number of space- and airborne instruments are used to estimate soil moisture. Each of the sensing approaches has distinct advantages and disadvantages. There is increasing interest in combining active and passive measurements in order to realize the advantages and alleviate the disadvantages. In order to combine active and passive measurements, their covariations with respect to soil moisture need to be known. The covariation is dependent on how the active and passive microwaves interact with vegetation canopy and soil surface. In this paper, we introduce a physics-based model for the covariation of active and passive microwaves over soil surfaces with vegetation cover. The analytical form for a covariation function is derived which depends on the scattering and absorption of microwaves by soil and vegetation with different orientations, structures, and water contents. The main finding is that the covariation function $\beta $ is related to the roughness and vegetation losses in the two measurements. An increase in soil roughness or in vegetation cover leads to less negative values of $\beta $ , which is pronounced for dense and moist vegetation. Both the soil and vegetation components introduce a polarization dependence of $\beta $ that is caused by polarization-induced differences in soil scattering and oriented plant structures. The forward modeled covariations are plotted together with statistically derived covariation estimates from two months of global active and passive L-band observations of the Soil Moisture Active Passive mission. The physically modeled and statistically derived estimates of covariation are comparable in magnitude and scale. [ABSTRACT FROM AUTHOR]

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Aims and Objectives: Curing units in dental offices across Punjab are analyzed for a practical purpose. Materials and Methods: One thousand light-curing units regularly used by the dentists in dental offices across the state of Punjab were examined for their output intensity. Various factors include as follows: type, power of light-curing unit, material molecule formation on tip (YES/NO), diameter of guide tip, and frequency of bulb replacement. A radiometer, a magnifying glass, and a Vernier caliper were used. Data were collected and analyzed. Results: About 75.80% of dentists use light-emitting diode (LED) lights, while 24.20% utilize halogen lamps to cure dental composites. 36.60% of light-curing units of the state had light intensity below 300 mW/cm2, out of which 61.60% were quartz-tungsten-halogen (QTH) and 28.60% LED light-curing units. 17.40% of light-curing units recorded light intensity between 301 and 400 mW/cm2. 46% of light-curing units registered an output intensity of >400 mW/cm2. 79.60% of light units showed material particle buildup on light-curing tips. 62.40% of dentists never replaced the bulbs of their light-curing units. Two-third of dental the practitioners avoided infection control barriers on the tips of curing units. Conclusions: There is a deficit of knowledge among dental practitioners in Punjab regarding care of light-curing units. Dental light-curing units should be regularly checked and infection control remedies should be opted. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an analysis of the experimental measurements of the azimuthal anisotropy of the microwave emissions of a rough water surface. The experimental data were obtained using microwave radiometers with operating frequencies of ~37 GHz (a wavelength of ~8 mm) on the oceanographic platform of the Black Sea Hydrophysical Experimental Facility of the Russian Academy of Sciences in the period from 2005 to 2016. This paper describes the azimuthal anisotropy effect, experimental studies, measurement methods, and data processing. A qualitative comparison of the measurement results with the model calculations and other experimental studies of anisotropy was performed. It was shown that there is a strong sensitivity of the variation in the radio emissions of a rough water surface, both to the wind speed and to its direction at different incidence observation angles. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the functional dependence of the microwave emission of a rough water surface at a frequency of 37.5 GHz (wavelength of ~8 mm). The MiROSE model (Microwave Rough Ocean Surface Emission model) is based on the experimental studies of the own thermal radio emission of the water surface, which were carried out in 2005 and 2007 on the oceanographic platform of the Black Sea Hydrophysical Experimental Facility of the Russian Academy of Sciences. This paper demonstrates the steps of the simulation for selecting the optimal functions to describe the incident angle, wind, and temperature dependences of the increment of the own water surface emission. The following parameters can be calculated on the basis of the proposed model: the increment of the brightness temperature, radio-brightness contrast, and radio-brightness temperature for horizontal and vertical polarizations of the received emission. The model is applicable to water temperatures ranging from 12.5 to 25°C, wind speeds of 3-13 m/s, and incident angles of 30°-80° measured from the nadir. [ABSTRACT FROM AUTHOR]

Conventional scatterometer wind retrieval has been proved effective for low and moderate wind conditions. Under high wind conditions, especially for typhoons, the air–sea interactions are fierce, and usually the sea surface backscattering is complicated by rain, leading to degraded scatterometer wind quality. Under such circumstances, radiometers in different frequencies can provide information of rains and the complex air–sea interface. In this paper, an artificial neural network (ANN) was employed to combine the observations of the two sensors onboard HY-2A satellite: radiometer and scatterometer (HSCAT) to achieve wind field retrieving under typhoon conditions. The ANN was trained by using global/regional assimilation and prediction system (GRAPES) wind field data as true values. The established network is then verified by an independent dataset excluded from the training data. It is shown that the wind speeds and directions retrieved from the ANN are better than those of the operational HSCAT products as compared to GRAPES winds. Further comparison with the H*Wind product proves that the proposed ANN is effective in terms of high wind field retrieval. The research of this paper provides a nice reference for the typhoon wind retrieval from the HY-2A satellite and for the data processing of the coming HY-2 satellite series. [ABSTRACT FROM AUTHOR]

A high-resolution dual-band terahertz (THz) radiometer was designed to measure vertical distributions of chemical elements in the middle atmosphere of the Tibetan Plateau. A forward simulation, which always should be conducted firstly for the development of a matching retrieval algorithm, has not been done before. We use two radiative transfer models, ARTS and AM, to simulate the water vapor, ozone and carbon monoxide spectra on the plateau based on the spectral design of the THz radiometer. The emission line characteristics of the three gases in this spectral band are identified. Reasons for the differences in the spectral simulations between the two models are analyzed for individual gases. The impact of several different spectral parameter settings on the simulations are evaluated through a series of sensitivity experiments. This study suggests that the ARTS is more suitable for the development of the THz radiometer retrieval algorithm. An optimal parameter setting of the ARTS for the three elements are given. [ABSTRACT FROM AUTHOR]

The Soil Moisture Active Passive (SMAP) mission was launched on January 31, 2015. It is a combined L-band active/passive system envisioned for the measurement of soil moisture over land. In addition to the soil moisture measurement, the SMAP data readily permit retrievals of ocean surface winds and sea surface salinity. In the previous work, we have found that the SMAP radiometer displays sensitivity to ocean surface wind all the way up to the most extreme wind speeds, possibly as high as 70 m/s, far beyond what is capable with typical $C$ - and $Ku$ -bands ocean wind scatterometers. In this letter, we use the Rapid Scatterometer and stepped frequency microwave radiometer to further validate these SMAP radiometer-only high-wind speed retrievals. In addition, we consider the size of the retrieved high wind speeds, validating them with the Automated Tropical Cyclone Forecasting system B-deck files. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to investigate if autoclaving light-curing tips in sterilization packages using a properly maintained autoclave filled with distilled water reduced the buildup of boiler scale and allowed the tips to maintain their ability to transmit energy. Method and Materials: Thirty light-curing tips were divided into groups: control, never autoclaved; group 1, no light-curing tip treatment, autoclaved only; group 2, autoclaved and treated with the Demetron/Kerr Optics Maintenance Kit; group 3, autoclaved and treated with the EFOS Fiberoptic Cleaning Kit; group 4, autoclaved and treated with Shofu Brownie and Greenie polishing points; and group 5, autoclaved and treated with a standard rubber prophylaxis cup. The curing tips were packaged and subjected to 30 autoclave cycles in a clinical autoclave with standard loads of clinical instruments. The light transmission was measured with a curing radiometer. Results: Results showed a 7% decrease in energy transmission for the untreated tips compared to the control. Both polishing system groups demonstrated a 4% decrease. There was no significant difference between the control and the first three groups. The polishing point and prophylaxis cup groups shoed significantly decreased energy transmission (decreases of 11% and 25%, respectively) Conclusion: Light-curing tips can be autoclaved with routine packaged loads of clinical instruments and retain their ability to transmit light energy, provided that the tips are packaged and the autoclave is properly maintained and filled with distilled water. Commercially available optics maintenance kits are effective in removing deposits and restoring light energy transmission. [ABSTRACT FROM AUTHOR]

Methods for passive sensing the atmosphere in the microwave range are one of important directions of remote sensing of environmental protection. To develop simple and cost-effective technical solutions and radiometric measuring techniques is an important task. A simple mobile radiometric system of 3-cm wavelength range designed for meteorological research has been presented. The radiometer is made on the basis of modulation scheme with some features of construction elements and input calibration. A method for accurate determination of the sky brightness temperature used for calibrating radiometric system has been proposed. A variant of constructing a radiometer with the use of satellite converter gas been implemented.

The paper shows the possibility of determining of the radon by the radiometer on a base of multi-channel time analyzer of beta – decay products of radon. The radiometer consist of an electrostatic aerosol collector combined with the air intake, Geiger-Muller counter for detection of beta particles and multi-channel time analyzer. Accumulation time of aerosol sample takes up to 20 min, the time data processing is done by the radiometer about 5 hours. The data processing is at off-line mode using the computer decomposition process of decay spectrum.

Aim: The aim of the survey was to examine the output intensity of curing units and other related factors in private dental offices across Nellore urban area. Materials and Methods: A questionnaire was prepared about the type of curing unit, number of restorations performed in a week, maintenance of curing unit, frequency of changing bulb, measurement of output intensity, presence, or absence of composite build--ups on curing tips. The questionnaire was submitted to 100 private dental offices located in Nellore urban area. Each variable in the questionnaire had an impact on quality of the composite restoration. Each curing unit light tip was also observed for the presence or absence of composite build--up. The output intensity of the curing light was measured using a digital radiometer (Ivoclar). The average of the three readings of the output intensity was obtained for each curing light. The average output intensity was divided into three categories (850 mW/cm2). A significant reduction in output intensity is seen with both types of older light curing units. Nearly 50% of practitioners had never checked the light output of their unit. Conclusion: It was concluded that there is a general lack of awareness among dentists of the need for maintenance of these units.

A low-mass and low-volume dual-polarization L-band radiometer is introduced that has applications for ground-based remote sensing or unmanned aerial vehicle (UAV)-based mapping. With prominent use aboard the ESA Soil Moisture and Ocean Salinity (SMOS) and NASA Soil Moisture Active Passive (SMAP) satellites, L-band radiometry can be used to retrieve environmental parameters, including soil moisture, sea surface salinity, snow liquid water content, snow density, vegetation optical depth, etc. The design and testing of the air-gapped patch array antenna is introduced and is shown to provide a 3-dB full power beamwidth of 37°. We present the radio-frequency (RF) front end design, which uses direct detection architecture and a square-law power detector. Calibration is performed using two internal references, including a matched resistive source (RS) at ambient temperature and an active cold source (ACS). The radio-frequency (RF) front end does not require temperature stabilization, due to characterization of the ACS noise temperature by sky measurements. The ACS characterization procedure is presented. The noise equivalent delta (Δ) temperature (NEΔT) of the radiometer is ~0.14 K at 1 s integration time. The total antenna temperature uncertainty ranges from 0.6 to 1.5 K.

Continuous estimates of the vertical integrated precipitable water vapor content from the tropospheric delay of the signal received by the antennas of the global positioning system (GPS) are used in this paper, in conjunction with the measurements of the Meteosat Second Generation (MSG) spinning enhanced visible and infrared imager (SEVIRI) radiometer and with the lightning activity, collected here by the ground-based lightning detection network (LINET), in order to identify links and recurrent patterns useful for improving nowcasting applications. The analysis of a couple of events is shown here as an example of more general behavior. Clear signs appear before the peak of lightning activity on a timescale from 2 to 3 h. In particular, the lightning activity is generally preceded by a period in which the difference between SEVIRI brightness temperature (TB) at channel 5 and channel 6 (i.e., ∆TB) presents quite constant values around 0 K. This trend is accompanied by an increase in precipitable water vapor (PWV) values, reaching a maximum in conjunction with the major flash activity. The results shown in this paper evidence good potentials of using radiometer and GPS measurements together for predicting the abrupt intensification of lightning activity in nowcasting systems.

Climate on Earth is determined by the Earth Radiation Budget (ERB), which quantifies the incoming and outgoing radiative energy fluxes. The ERB can be monitored by non-scanning wide field-of-view radiometers, or by scanning narrow field-of-view radiometers. We propose an enhanced design for the wide field-of-view radiometer, with as key features the use of a near-spherical cavity to obtain a uniform angular sensitivity and the integration of the shuttered electrical substitution principle, eliminating long term drifts of the radiometer and improving its time response. The target absolute accuracy is 1 W/m 2 and the target stability is 0.1 W/m 2 per decade for the measurement of the total outgoing Earth’s radiation. In order to increase the spatial resolution and to separate the total outgoing radiation into reflected Solar and emitted thermal radiation, we propose the joint use of the radiometer with wide field-of-view Shortwave (400−900 nm) and Longwave (8−14 μm) cameras. This paper presents the concept and design of the novel wide field-of-view radiometer, including simulations and analyses of its expected performance. We focus on mechanical design and the measurement characteristics based on optical and thermal analyses. In combination with the cameras, we obtain an estimated accuracy of 0.44 W/m 2 .

Land Surface Temperature (ST) represents the radiative temperature of the Earth’s surface and is used as input to hydrological, agricultural, and meteorological science applications. Due to the synoptic nature of satellite imaging systems, ST products derived from space-borne platforms are invaluable for estimating ST at the local, regional, and global scale. In the past two decades, an emphasis has been placed on the need to develop algorithms necessary to deliver accurate surface temperature products to support the needs of science users. However, corresponding efforts to validate these products are hindered by the availability of quality ground-based reference measurements. The NOAA Surface Radiation Budget (SURFRAD) network is commonly used to support ST validation efforts, but their instrumentation is broadband (4−50 μ m) and several of their sites lack spatial uniformity. To address the apparent deficiencies within existing validation networks, this work discusses a prototype radiometer that was developed to provide surface temperature estimates to support validation efforts for spaceborne thermal instruments. Specifically, a prototype radiometer was designed, built, and calibrated to acquire ground reference data to be used to validate ST product(s) derived from Landsat 8 image data. Lab-based efforts indicate that these prototype instruments are accurate to within 1.28 K and initial field measurements demonstrate agreement to Landsat-derived ST products to within 1.37 K.

Accurate prediction of sea surface emission is the key for sea surface salinity retrieval from satellite microwave radiometer. In order to retrieve salinity from satellite observation, several sea surface microwave emission models have been developed based on theoretical or empirical methods and validated by in-situ measurements in different regions. However, their performances are still unclear in the Chinese coastal waters. In this study, based on two cruises measurements in the East China Sea (ECS), including the brightness temperature measured by a shipborne microwave radiometer and other auxiliary data (sea surface salinity, sea surface temperature and wind speed), the performances of different sea surface emission models are tested. The results showed that the developed models provide fairly good accuracy in predicting brightness temperature; for example, the accuracy of small perturbance/small scale approximation model (SPM/SSA), two-scale model (TSM) and empirical model is in the range from 0.6 K to 3 K. Moreover, the TSM and empirical models are further improved by optimizing the model parameters in the ECS. Finally, the sea surface salinity were retrieved from shipborne measured data based on the improved models, and the results show that the root mean square (rms) differences between retrieved and in-situ sea surface salinity is about 0.4 psu, indicating the significant improvement by the regional model parameters.

To improve the thermal modelling of high power isotope separation on-line (ISOL) targets at TRIUMF, an optical technique is being developed that allows for direct off-line and on-line temperature measurements of targets for radioactive isotope production. In this setup the light coming from a hot target through the ionizer opening is collected via a set of optics and coupled into a spectrometer. Thus, from the emission spectrum and Planck's law, the target temperature can be deduced. Tantalum targets were heated to high temperatures and preliminary temperature measurements confirm the correlation between the spectrum of the radiation emitted from the target and the currents used to resistively heat the targets. The final goal is to apply this technique to on-line targets and correlate the isotope releases with the target temperatures for a better understanding of the diffusion and effusion processes happening in the target and for optimizing the delivery of short-lived species. [ABSTRACT FROM AUTHOR]

Ground-based estimates of aboveground wet (fresh) biomass (AWB) are an important input for crop growth models. In this study, we developed empirical equations of AWB for rice, maize, cotton, and alfalfa, by combining several in situ non-spectral and spectral predictors. The non-spectral predictors included: crop height (H), fraction of absorbed photosynthetically active radiation (FAPAR), leaf area index (LAI), and fraction of vegetation cover (FVC). The spectral predictors included 196 hyperspectral narrowbands (HNBs) from 350 to 2500 nm. The models for rice, maize, cotton, and alfalfa included H and HNBs in the near infrared (NIR); H, FAPAR, and HNBs in the NIR; H and HNBs in the visible and NIR; and FVC and HNBs in the visible; respectively. In each case, the non-spectral predictors were the most important, while the HNBs explained additional and statistically significant predictors, but with lower variance. The final models selected for validation yielded an R2 of 0.84, 0.59, 0.91, and 0.86 for rice, maize, cotton, and alfalfa, which when compared to models using HNBs alone from a previous study using the same spectral data, explained an additional 12%, 29%, 14%, and 6% in AWB variance. These integrated models will be used in an up-coming study to extrapolate AWB over 60 × 60 m transects to evaluate spaceborne multispectral broad bands and hyperspectral narrowbands.

The paper describes a method of simultaneous measurements of kinematic parameters of a high-speed process by a microwave radio interferometer with a 3-mm range of wavelengths and the brightness temperature of the same process by the microwave radio interferometer operating in the radiometer mode. The methods of radiometer calibration and analysis of radiometric data are described. Results of experimental investigations are reported by an example of measuring the detonation velocity and estimating the brightness temperature of the detonation front in TNT. [ABSTRACT FROM AUTHOR]

Solar UV radiation reaching the Earth's surface is known to have various effects on human health and on the ecosystem. Ground-based measurements of surface UV radiation are spatially sparse and in many cases do not provide long time series. Higher spatial coverage can be provided by measurements from satellite based instruments, but these measurements need to be compared to ground-based measurements of sufficient quality before they can be used in health and ecosystem applications. Here, we compare the measurements of surface solar UV radiation in UVA (315–400 nm) and UVB (280–315 nm) bands with the satellite retrievals (CERES) and validate the latter at an urban location, Delhi, India. We have also used MODIS-retrieved aerosol optical depth (AOD) and cloud optical depth (COD) data to see the effect of atmospheric opacity on UV radiation. Ground-based measurements of UVA and UVB were performed from 01 October, 2012 to 30 September, 2015. Correlations between daily surface measurements and CERES-derived surface UV fluxes showed very good agreement (r ∼ 0.92–0.93) over Delhi. We found a negative correlation between UV fluxes and AOD over Delhi during all seasons. A unit increase in AOD leads to a decrease of ∼4–5 Wm -2 in UVA and ∼0.09–0.14 Wm -2 in UVB over Delhi. The trend analysis from monthly mean CERES-derived UV fluxes for 17 years data reveals that UVA and UVB are decreasing ∼0.07 Wm -2 yr −1 and 0.003 Wm -2 yr −1 , respectively with AOD increase (∼0.005 yr −1 ) over Delhi. The simultaneous increase in aerosol loading with decrease in UV fluxes at the surface may be explained as a masking effect of ever increasing pollution on surface UV radiation over Delhi. Our results show ∼10% and ∼20% decrease (with respect to mean) in UVA and UVB surface fluxes, respectively during last 17 years. [ABSTRACT FROM AUTHOR]

A new 0.1° gridded daily sea surface temperature (SST) data product is presented covering the years 2003-2015. It is created by fusing satellite SST data retrievals from four microwave (WindSat, AMSR-E, ASMR2 and HY-2A RM) and two infrared (MODIS and AVHRR) radiometers (RMs) based on the optimum interpolation (OI) method. The effect of including HY-2A RM SST data in the fusion product is studied, and the accuracy of the new SST product is determined by various comparisons with moored and drifting buoy measurements. An evaluation using global tropical moored buoy measurements shows that the root mean square error (RMSE) of the new gridded SST product is generally less than 0.5°C. A comparison with US National Data Buoy Center meteorological and oceanographic moored buoy observations shows that the RMSE of the new product is generally less than 0.8°C. A comparison with measurements from drifting buoys shows an RMSE of 0.52-0.69°C. Furthermore, the consistency of the new gridded SST dataset and the Remote Sensing Systems microwave-infrared SST dataset is evaluated, and the result shows that no significant inconsistency exists between these two products. [ABSTRACT FROM AUTHOR]

This paper describes a novel cost effective narrow-beam radiometer what was designed to measure incident heat flux at a specific location in high temperature and high pressure combustor. Beyond the radiometer the whole measurement assembly contains a water cooled plate for cold background, a high pressure window transparent for visible and IR radiation and a radiometer position/angle adjustment tool. The thermopile based radiometer measures the total heat radiation in a wavelength range of 0.6–8 µm. A special view tube was developed for decreasing the view angle to 0.35°, what angle was dictated by the dimensions of the combustor and the associated port sizes. Calibration curves were measured using a high temperature black body calibrator and the uncertainty of the measurement was evaluated. Although the presented radiant heat flux measurement method was developed for a specific combustor, it can be easily implemented for various combustion applications as well. [ABSTRACT FROM AUTHOR]

The Mars Environmental Dynamics Analyzer (MEDA) is a suite of environmental sensors onboard NASA’s Mars 2020 mission. The Thermal InfraRed Sensor (TIRS), developed at Centro de Astrobiología of Spain, is one of the six sensors comprising MEDA, and it will measure the net thermal infrared radiation and reflected solar radiation at the surface, as well as the atmospheric and surface skin temperatures using five different channels. In combination with MEDA's other sensors, TIRS will allow the quantification of the surface energy budget and the determination of key geophysical properties of the terrain such as the albedo and thermal inertia. Here we present a general description of the TIRS, its channels scientific requirements, and the mechanical and thermal design. Then, a detailed sensor mathematical model and a sensitivity analysis to model uncertainties are described. Some characterization test results to model parameters identification are included. Finally, accuracy and resolution calculus for each channel versus operational temperature is presented. The calculus is performed based on sensitivity equations, the practical tests results and the estimated values for different uncertainty sources. [ABSTRACT FROM AUTHOR]

Predictable quantum efficient detectors (PQEDs), based on photoelectric effect in silicon semiconductor, have proved their potential as optical radiant power primary standard. At present, simulations for semiconductor devices are the common method to predict the response of a PQED. As an alternative, this work investigates the feasibility of an experimental technique, the self-calibration of silicon photodiodes at room temperature by means of temperature sensors. A device which compares two physics principles by optical power, working both as a photodetector and a radiometer based on electrical substitution, was made. The device allows for measuring the current generated under irradiation (in photocurrent mode) and the heating of the system, induced by a laser or forward biasing, to determine the optical power (in thermal mode). The feasibility study consists of testing the equivalence between both modes and establishing the suitable range of optical power. The range of optimum optical power level, where both modes run in the linear domain at the present configuration, is from 300 µW up to 1 mW. Within this range, the optical power experimental uncertainty is lower than 1%. [ABSTRACT FROM AUTHOR]

A wideband (30% relative bandwidth) correlation and detection module based on substrate-integrated waveguide (SIW) technology intended for a radio astronomy polarimeter is presented. The SIW circuit is a six-port network with two input ports that are correlated in two hybrid couplers and their corresponding output signals are routed to Schottky diode detectors, which are designed using microstrip technology and assembled within the same system. The designed SIW structure includes hybrid couplers, power dividers, a 90° phase shifter, and 90° bends, providing a real implementation of a functional system with improved bandwidth performance from 35 to 47 GHz. Experimental results are in concordance with simulations, and they validate the module operation for the proposed application. [ABSTRACT FROM AUTHOR]

Aerosol is an important part of the earth-atmosphere system. It can directly and indirectly influence solar radiation and then affect the energy balance of earth-atmosphere system. AERONET, as the largest ground-based observation network, provides multiparameters of aerosol from more than 600 hundred sites using sun-sky radiometer, which contains 9 channels from 340 nm to 1640 nm. Among which, 1020 nm channel is greatly influenced by the temperature. In this paper, a new correction method of 1020 nm band is introduced. The new method transfers the temperature correction coefficient of the master radiometer to the comparative one. The filed calibration experiment shown that the temperature correction coefficient obtained by this method is close to the result from the temperature controlled chamber, and the difference is about 2.1%. This new method is easy-to-use, and its accuracy is comparable to the standard one. It is more applicable for large-scale instrument calibration. In principle, this method is applicable to all bands of the sun-sky radiometer. [ABSTRACT FROM AUTHOR]

Digital cross-correlation is central to many applications including but not limited to Digital Image Processing, Satellite Navigation and Remote Sensing. With recent advancements in digital technology, the computational demands of such applications have increased enormously. In this paper we are presenting a high throughput digital cross correlator, capable of processing 1-bit digitized stream, at the rate of up to 2 GHz, simultaneously on 64 channels i.e., approximately 4 Trillion correlation and accumulation operations per second. In order to achieve higher throughput, we have focused on frequency based partitioning of our design and tried to minimize and localize high frequency operations. This correlator is designed for a Passive Millimeter Wave Imager intended for the detection of contraband items concealed on human body. The goals are to increase the system bandwidth, achieve video rate imaging, improve sensitivity and reduce the size. Design methodology is detailed in subsequent sections, elaborating the techniques enabling high throughput. The design is verified for Xilinx Kintex UltraScale device in simulation and the implementation results are given in terms of device utilization and power consumption estimates. Our results show considerable improvements in throughput as compared to our baseline design, while the correlator successfully meets the functional requirements. [ABSTRACT FROM AUTHOR]

The paper investigates the theory of operation of a passive millimeter-wave seeker sensor using a fast electronic sequential-lobing technique and the experimental validation obtained through laboratory trials. The paper analyzes in detail the theoretical performance of a difference channel sensor and a pseudo-monopulse sensor deriving agile formulas for the estimation of target angular tracking accuracy and the subsequent experimental validation. [ABSTRACT FROM AUTHOR]

A correlation analysis of the model calculations and experimental measurements of wind-speed sensitivity of a rough sea-surface microwave emission at a frequency of 37.5 GHz are presented. The field data used in the research were collected over 3 years in the summer and autumn periods at the oceanographic platform of the Marine Hydrophysical Institute, Russian Academy of Sciences (RAS). A hypothesis about a significant correlation between the model calculations and experimentally measured sea-surface emission ability caused by wind forcing was formulated and tested to reveal this correlation. An evaluation of the discrepancy between the model and experimental data has been performed by an analysis of residuals. Our studies have shown that among the selected models not a single one adequately describes the experimental data. [ABSTRACT FROM AUTHOR]

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