Remote sensing of a film layer of marine surface in the IR spectral range

The reflectivity and the diffuse component of the reflection coefficient resulting from scattering by wave ripples as well as the temperature and permittivity of the boundary film layer of the sea surface are obtained from the results of in situ remote correlation measurements of the radiation intensities of the sea surface and the atmosphere performed in the presence of wind waves. The permittivity of water in the layer where radiation is formed is determined. It is found that, in field conditions, the imaginary part of the permittivity of water in the 0.2-mm-thick surface layer exceeds the value commonly used in standard models. This effect can be explained by lowering of the relaxation time of dipole molecules by a factor of 1.5–2.0 because of the presence of substantial concentrations of nonpolar gases, which are present in the thin surface water layer due to exchange processes between the atmosphere and the sea.

Comments that the authors of the original paper (see Song and Chen, ibid., vol.41, no.10, p.1414-1421, 1993) wish to determine the transient electromagnetic field generated in a conducting medium by an impulsive current in a short electric dipole. Their approach and their results, however, seem to be questionable. To start with, their choice of a delta-function excitation causes serious mathematical difficulties which have been overlooked. Because the spectrum of the delta-function pulse extends over all frequencies with equal Fourier amplitudes, the assumption that the conducting medium, specifically sea water, is characterized by frequency independent permittivity and conductivity is incorrect. The authors reply that they are aware that the conductivity and permittivity of sea water is frequency dependent. They made the approximation of constant conductivity and permittivity for two reasons. First, the exciting impulse current contains all the frequency components from zero to /spl infin/. The second reason for the assumption of constant conductivity and permittivity is that with this assumption we are able to obtain an exact solution for the EM field excited by an impulse current.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The feasibility of Antarctic sea ice detection based on shipborne global positioning system reflectometry (GPS-R) technology is shown in this paper. Because the permittivity of sea water is much higher than that of sea ice, the reflected left-handed circular polarized (LHCP) GPS signal (RL) reflection coefficient of sea water is markedly higher than that of sea ice. The polarization ratio of RL to the direct right-handed circular polarized (RHCP) GPS signal (DR) is used to distinguish between sea water and sea ice in this paper. The experiment was performed on the ship “XueLong” for approximately 9 days from December 2014 to January 2015 during the 31st Chinese National Antarctic Research Expedition (CHINARE 31). The sea ice concentration data with a 25 km × 25 km spatial resolution derived from the National Snow and Ice Data Center (NSIDC) are used for validation and some pictures of sea ice taken from “XueLong” are shown for comparison. The polarization ratios (RL/DR) are calculated, and the correlation coefficient between the polarization ratios (RL/DR) and the sea ice concentrations is −0.66.

The results of radiometric remote simultaneous field measurements of the temperature and radiation capacity of the upper layer of the sea-surface temperature film 0.2 mm thick are presented. The measurements were conducted in the presence of wind waves and were characterized by an increased accuracy, which was achieved owing to the use of measurements of the intensity of radio radiation from the surface illuminated by radiation of a specified varying power. In our experiment, this illumination was provided by the radio radiation of the atmosphere, whose radiance temperature varies significantly, depending on the frequency at the slope of the absorption band of molecular oxygen (52.5–56 GHz). As a result, the radiation capacity and temperature of the skin layer were determined from the correlation dependence between the radiance temperatures of the surface and atmosphere measured by a radiometer-spectrometer in a number of channels separated in frequency. The radiance temperatures of the sea and atmosphere were measured at four frequencies of the 5-mm spectral range (53–55 GHz) on a vertical polarization. For absolute measurements, a calibration method was developed on the basis of a blackbody disk and two reflecting mirrors with the same solid angles. The measured values of the radiation capacity are variable and substantially smaller than the theoretical values determined by the models accepted for the permittivity of water and sea roughness. A possible cause of this can be the change of the permittivity of water in a thin surface layer of the temperature film (0.2 mm) due to the concentration of gases dissolved in water and surface-active substances within this layer.

Problem Statement and Purpose. The evaluation of thermohaline parameters of the seawater is the most accessible indicator of the variability of processes and the determination of trends in their development. The use of observations of the temperature and salinity of the surface layer of water, obtained by their continuous registration from the board of a specially equipped vessel, allows for obtaining a detailed picture of the statistical variability along the direction of movement and characteristics of the hydrological structures found on the way. The continuous recording of the seawater surface layer’s temperature and salinity is progress in the development of modern oceanology in comparison with the existing point measurements. The purpose of our research is to evaluate the features of the distribution of temperature and salinity of surface waters along the meridian and their temporal variability in the western part of the Black Sea in 1998–2000 along the entire route from the port of Odesa to the Bosphorus Strait. Data &amp; Methods. The basis for the research was the data of continuous registration of the surface layer seawater's temperature and salinity on the Odesa-Istanbul route and back during 30 months (from 3.05.1998 to 25.10.2000). The data was obtained during the ship's 172 commercial voyages scientific and research vessel "Georgiy Ushakov", which was equipped with a stationary system of continuous recording of thermohaline parameters. The distance between these points was approximately 600 km and about 1,500 values of temperature and salinity of the seawater’s surface layer were obtained. According to the calculated average monthly values of temperature and salinity of the surface layer of water on the quasi-meridional route from Odesa to the Bosphorus Strait for 1998–2000. The space-temporal variability was estimated for the average monthly values of the seawater surface layer's temperature and salinity on the quasi-meridional route from Odesa to the Bosphorus Strait for 1998–2000 years. A modern electronic climate array of the Black Sea water's thermohaline characteristics for 1991–2020 was used for comparison. Results. The calculated average temperature for 3 years was 14.84 °C, salinity 16.98‰, and the average annual fluctuations did not exceed 0.1 of the characteristic value. In the latitudinal distribution of the characteristics, there are differences between the northern and southern parts of the sea: the increase in the spring-summer period of the average monthly temperature occurs synchronously, and the decrease – asynchronously in the autumn-winter period (the maximum warming lasts for 1.5 months on the Turkish coast); in the northern part of the third section, water with reduced salinity values (15–16‰) is occupied, and the water in 2/3 of the southern part has a salinity of 17–18‰ and higher (the amplitude of the salinity’s fluctuations in the NWBS is 3 times greater). The minimum water cooling occurs in January-February (near the Turkish coast – 6–7 °C, near the northern coast – up to 2 °C); the minimum salinity is in May (15.96–16.30‰), and the maximum in November and February (17.59–17.79‰). An inverse relationship was obtained between fluctuations in salinity and flow rates of the Danube (maximum between 44.5 and 45.5°N with a lag of flow rates of 1 month). The region has been identified on the route between 42° and 44°N that retains its characteristics throughout the year acquired during the period of autumn-winter convection. Also, according to the distribution of salinity along the route, 4 regions were identified that represented frontal and gradient zones: the Bosphorus (between 41.25 and 42.0°N), the open sea area (between 44 and 45°N), the Dniester (between 45–46°N) and Dneprobugsky (between 46 and 46.5°N).

Accurate retrievals of liquid water path (LWP) from passive microwave radiometers rely on the use of radiative transfer models to describe the absorption of radiation by various atmospheric components. When clouds are present, atmospheric absorption is affected by the dielectric properties of liquid water. In this paper, we use measurements from four microwave radiometers to assess four models of the complex permittivity of water. The observations are collected at five frequencies between 23.8 and 170 GHz. The purpose of the study is to compare measurements of microwave absorption with model computations in supercooled liquid clouds that have temperatures between 0 °C and -30 °C. Models of liquid water permittivity in this temperature range suffer from a lack of laboratory measurements and are generally derived from the extrapolation of available data. An additional rationale for this work is to examine to what degree the use of different dielectric models affects the retrieval of LWP in supercooled liquid clouds. Inaccuracies in modeling the water permittivity at low temperatures are likely one of the largest sources of retrieval uncertainty in supercooled clouds, uncertainty that could offset the advantages offered by the enhanced sensitivity of channels at frequencies at and above 90 GHz relative to lower frequencies.

Analyses of temperature and humidity profiles and heat balance of the surface boundary-layer in the hinterland of the Taklimakan Desert

Horizontal wave number spectra of temperature in the unstably stratified oceanic surface layer were determined from measurements on a bow boom at a depth of 2 m. Spectra were estimated in the wavelength band from 2 m to 2 km, normalized in accordance with Monin‐Obukhov similarity theory, and averaged in groups with similar stability parameter and fractional mixed layer depth. The shapes of the wave number‐weighted oceanic spectra agree qualitatively with observed and modeled atmospheric spectra, including the wavelength of the peaks and the variation of peak wave number with stability. However, the peak spectral levels disagree by as much as a factor of two and the variation of spectral level with stability is in the opposite sense for the oceanic and atmospheric spectra. The wave number of the peak in the near neutral oceanic spectrum is similar to the wave number of the peak in the longitudinal velocity spectrum observed in the atmospheric surface layer, which is consistent with temperature acting as a passive tracer in near neutral conditions. The wave number of the peak in the free convection oceanic spectrum is similar to the wave number of the peak in the spectrum of vertical velocity observed in the atmospheric surface layer during free convection, which reflects the dynamical role played by temperature in a freely convecting boundary layer. The difference between oceanic and modeled near‐neutral spectral levels at a wavelength of 2 m suggests that dissipation could be enhanced (up to a factor of three) by surface wave breaking.

Studying the soil temperature field and its variation law is of great significance to the real-time service of agricultural production. To solve the problems of low detection efficiency and difficulty of distributed detection, a distributed detection method of soil temperature field using wavelength division multiplexing and space division multiplexing technologies based on fiber Bragg grating (FBG) sensor is proposed. In this scheme, the stainless steel tube encapsulating the FBG string was vertically buried in the measured soil, and the tunable laser method and the peak-seeking algorithm were used to demodulate the wavelength of each sensor of the FBG string. The soil temperature field measurement experiments were carried out in the farmland environment. The experimental results show that the proposed method can detect the soil temperature field in real time. The internal temperature of soil changes periodically with the periodic change of surface environment temperature. With the increase of depth, the influence of surface temperature on soil temperature gradually decreases, and the amplitude of soil temperature oscillation gradually decreases, but the hysteresis effect of temperature peak becomes more and more obvious. The ambient wind speed can reduce the temperature of soil surface and shallow layer. Soil moisture affects the speed of temperature transfer from the surface layer to the deep layers, and the hysteresis effect of temperature peak is more significant in the soil with higher moisture. Solar radiation has a great influence on the temperature of soil surface and shallow layer.

Anion affinities, gammaX-, for the aerial interface of aqueous (Br- + NO3- + I- + SCN- + BF4- + ClO4-) solutions are determined by electrospray ionization mass spectrometry. The composition of the ions ejected from the surface of fissioning nanodroplets shows that gammaX- increase (decrease) exponentially with anionic radii, aX-(dehydration free energies, dGX-), and selectively respond to the presence of surfactants. BF4-, the least hydrated and polarizable anion of the set, has one of the largest gammaX- values. Non-ionic surfactants decrease gammaI- and gammaSCN- but increase gammaBF4-. Cetyltrimethyl ammonium markedly enhances the gammaX- of smaller anions. A similar but weaker effect is observed upon lowering the pH of the bulk solutions from 8.2 to 3.0. Dodecyl sulfate has a negligible effect on gammaX-. Considering that (i) universal many-body electrodynamic interactions will progressively stabilize the interfacial layer as its dielectric permittivity falls relative to that of the bulk solution and (ii) water permittivity is uniformly depressed by increasing concentrations of these anions, we infer that the observed Hofmeister correlation, ln gammaX- infinity - dGX-, is consistent with the optimal depression of the permittivity of the drier interfacial layer by the least hydrated ions. Interfacial ion-ion interactions can significantly influence gammaX- in environmental aqueous media.

[1] The ENSO-related spatial patterns and global averages of ocean temperature, salinity, and steric height are estimated from over 7 years of Argo data, 2004–2011. Substantial extratropical variability is seen in all variables in addition to familiar tropical ENSO signals. Surface layer (0–100 dbar) and subsurface (100–500 dbar) temperature variations are both important in determining steric height and sea surface height patterns. For the two years prior to the 2009 El Nino, the upper 100 dbar of the ocean gained 3.3 × 1022 J yr−1 of heat, while the 100–500 dbar layer lost a similar amount. The ENSO-related vertical redistribution of globally-averaged heat content between surface and subsurface layers, occurring throughout the record, is due primarily to changes in the east-west tilting of the equatorial Pacific thermocline. The large temperature changes in the individual layers mask the smaller vertically-averaged temperature change, in which the ocean loses heat when the surface layer is anomalously warm and gains heat when the surface layer is cool.

Carbon cycling associated with biological soil crusts, which occupy interspaces between vascular plants in drylands globally, may be an important part of the coupled climate-carbon cycle of the Earth system. A major challenge to understanding CO2 fluxes in these systems is that much of the biotic and biogeochemical activity occurs in the upper few mm of the soil surface layer (i.e., the ‘mantle of fertility’), which exhibits highly dynamic and difficult to measure temperature and moisture fluctuations. Here, we report a multi-sensor approach to simultaneously measuring temperature and moisture of this biocrust surface layer (0–2 mm), and the deeper soil profile, concurrent with automated measurement of surface soil CO2 effluxes. Our results illuminate robust relationships between biocrust water content and field CO2 pulses that have previously been difficult to detect and explain. All observed CO2 pulses over the measurement period corresponded to surface wetting events, including when the wetting events did not penetrate into the soil below the biocrust layer (0–2 mm). The variability of temperature and moisture of the biocrust surface layer was much greater than even in the 0–5 cm layer of the soil beneath the biocrust, or deeper in the soil profile. We therefore suggest that coupling surface measurements of biocrust moisture and temperature to automated CO2 flux measurements may greatly improve our understanding of the climatic sensitivity of carbon cycling in biocrusted interspaces in our study region, and that this method may be globally relevant and applicable.

Modeling wear of different surface layers of agricultural tools in soil abrasive mass

Patterning and pattern selection in a surface layer: Feedback between point defects population and surface layer temperature variations

Texture depth is one of the most important indexes reflecting the skid resistance performance of asphalt pavement. Temperature has effect on the texture depth of asphalt pavement. There is no effective temperature correction method on the texture depth index in China, which leads to the phenomenon that the test texture depth could not reflect the true skid resistance performance of pavement structure. In order to effectively analyze the temperature influence on the skid resistance of asphalt pavement, a temperature correction method of sensor measured texture depth (SMTD) index was proposed based on the SMTD data and equivalent temperature of asphalt surface layer in RIOHTrack full-scale track. The annual equivalent temperature at 4cm location of asphalt surface layer was taken as the correction reference temperature. The Boltzmann function was adopted to establish the relationshi p between the SMTD index and the daily equivalent temperature of asphalt surface layer. The mean square error of temperature correction model for SMTD index is 0.977. The maximum error of temperature correction model for SMTD index is 2.601%, which meets the detection requirements on road engineering. The temperature correction method is significant to reflect the SMTD index change of pavement skid resistance performance, improve the evaluation accuracy of pavement skid resistance, and improve the safety of driving on highway.