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Annona squamosa (AS) and Cinnamomum tamala (CT) leaves have been used traditionally and have well reported various pharmacological activities which justify their topical use. But the majority of compounds present are phenolic compounds which due to their polar nature are unable to permeate through the skin. Therefore, polyherbal phytosomes of ethanolic extracts of AS and CT were combined in a ratio of 1:1 to get polyherbal Ethanolic extract (PHEE) and polyherbal phytosomes (PHP) were prepared and optimized using Response Surface methodology by applying Central Composite design (CCD) for studying the effect of drug soya lecithin ratio and speed of rotation on responses like vesicle size and entrapment efficiency. Followed by numerical optimization, PHP with vesicle size of 215.5 ± 0.45 nm and Entrapment efficiency of 85.24 ± 0.05% were obtained. These PHP were characterized with FTIR, DSC, SEM and XRD. The PHP showed % cumulative drug release of 84.22 ± 5.62%. For easy application on the skin these phytosomes were incorporated in Carbopol 934 gel matrix and evaluated for physical appearance, pH, viscosity and drug content. The ex vivo permeation of the phytosomal gel (PG) was compared with a conventional gel containing PHEE. A significant improvement in permeation was observed in case of PG with 36.62 ± 3.33 µg/cm2 of drug permeated in 24 hours whereas 17.06 ± 1.54 µg/cm2 through the conventional gel. The PHP and PG were found stable during stability studies for six months. Polyherbal phytosomal gel can be a good carrier for herbal extracts for topical delivery. [ABSTRACT FROM AUTHOR]

Inland and coastal environments are complex ecosystems composed of suspended and dissolved materials, affecting light propagation within the water column. Satellite-based water quality research relies on water optical properties provided by optical sensors on board of polar orbit satellites since the 1980's. Specifically, Geostationary (GEO) ocean colour satellites offer high temporal resolution (e.g. every 15-minute observations), moderate spatial resolution (0.5–1 km) at regional scale, making them a promising alternative to polar orbiting satellites for near-continuous monitoring of highly dynamic aquatic ecosystems. This literature review examines the evolution of geostationary satellite technology and its applications in monitoring inland and coastal waters. A summary of the most relevant studies using geostationary sensors is provided for key water quality indicators such as chlorophyll-a and algal organisms, total suspended solids, and turbidity. Also, geostationary missions were well-detailed, with their available sensors and characteristics. Although this research topic is still incipient, recent studies have demonstrated the potential of GEO multi-spectral observations in understanding sub-daily water quality patterns. Notably, most research studies have focused on Asia, suggesting unexplored opportunities globally. Advanced Himawari Imager (AHI) and Geostationary Ocean Colour Imager (GOCI) have been used to improve water quality estimates, and inherent challenges were documented, such as algorithm validation, limited spatial resolution, and high volume of images and auxiliary files to be managed. The opportunities for new studies range from algorithm development for atmospheric correction, cloud masking, and bidirectional reflectance corrections to inter-comparison with existing sun-synchronous satellites. Geostationary satellites are promising avenues for future research on near-continuous monitoring of inland and coastal water resources. [ABSTRACT FROM AUTHOR]

With the increased availability of multi-view satellite images, the number of investigations on 3D urban scene reconstruction from multiple satellite images is also increasing. Conventional Multi-View Stereo (MVS) pipelines require the calibrated pose information of the satellite cameras to determine the epipolar geometry and the 3D structure of the stereo correspondences. In this study, we propose a novel Monocular Height estimation and Fusion (MHF) method for 3D reconstruction from uncalibrated multi-view satellite images. By employing a learned monocular depth network, the proposed method first obtains the height map of each satellite image. Second, all height maps obtained from the multi-view images are fused to a refined height map in each image plane. To fuse the height maps, all maps are affine transformed to a virtual reference coordinate system and the transformed maps are then projected to the image plane of each camera coordinate system. The monocular depth network was trained and evaluated on the Data Fusion Contest 2019 (DFC19) dataset including Jacksonville, FL, and Omaha, NE. We also evaluate the ATL-SN4 dataset covering Atlanta, GA to test on untrained new urban scenes. [ABSTRACT FROM AUTHOR]

Synthetic Aperture Radar (SAR) plays an important role in marine ship management due to its all-weather, multi-band, and multi-polar characteristics, but the complex environment on the ground and the limitation of the imaging principle lead to the existence of large noise interference in SAR imaging, which poses a greater challenge to the existing ship detection algorithm. To address the problem of low detection rate and high false alarm rate of ship detection in noise-laden SAR images, we propose a detection algorithm based on convolutional neural network and transformer. First, we design the processing structure of multi-scale feature maps based on the advantages of transformer global processing capability, then we use weighted fusion of different scale feature maps after global processing to enhance the detection capability of the model for noise-containing targets, and finally, the model is evaluated using the high noise SAR datasets (HNSAR) we constructed. The experimental results show that our model has better detection of noise-containing SAR images compared with other deep learning models. [ABSTRACT FROM AUTHOR]

We present a generalisation of the Maier-Saupe (MS) theory that incorporates the description of the ferroelectric nematic phase (NF) within its scope of application. The extension of the theory is carried out in a natural way, by adding to the nematic potential of MS a term proportional to cosθ and to the polar order parameter , where θ is the angle between the long molecular axis and the spontaneous polarisation. The NF phase can be reached by cooling from the isotropic phase with or without the formation of an intermediate normal nematic phase, depending on the relative intensity of the polar and non-polar terms of the nematic potential. For both phase sequences all the transitions are first order. The temperature dependence of the polar and non-polar order parameters is calculated, and some results derived from the theory are compared with the experimental observations. It is argued that the theory is a valuable first approximation to describe some of the properties of ferroelectric nematics. [ABSTRACT FROM AUTHOR]

The rapid decline of Arctic sea ice has been reminding us the significant impacts caused by global warming. However, the other side of the coin is that this opens a window to utilize the Arctic sea routes in the summer seasons, bringing remarkable economic benefits for ocean transportation between Asia and Europe. However, commercial vessels with low ice classes must tackle substantial environmental challenges in the Arctic sea routes, particularly those caused by variable sea ice, even in the melting seasons. Therefore, the science-based support for shipping safety in the Arctic sea routes is being given more prominence. Emerging satellite remote sensing technology plays a critical role in environmental monitoring in the Arctic. This paper reviews state-of-the-art satellite observations on monitoring sea ice and potential applications on supporting shipping activities in the Arctic Ocean. Moreover, we introduced a recently developed system based on satellite observations to support the safe transportation of Chinese cargo vessels in the Arctic northern sea route, demonstrating the efforts by both the science and business communities to promote the development of the polar silk road. [ABSTRACT FROM AUTHOR]

Evapotranspiration (ET) estimates based on remote sensing are constrained by the spatial and temporal resolution of spaceborne observations. Therefore, the choice to be made is whether modelling at high temporal resolution with geostationary satellites at the cost of the spatial detail, or spatially detailed instantaneous modelling at overpass-time with polar-orbit satellites. This study aimed at exploiting the strength of both modelling approaches and derive daily ET estimates with cell size 1.0 km. The study was conducted in four sites with different land cover arrangements and catalogued as wetlands. The methodological approach was based on the algorithm behind the operational ET product of the Satellite Application Facility on Land Surface Analysis (LSA-SAF) initiative. The examined period comprised the end of the Spot-Végétation (Spot-V) mission and the first year of Proba-V operational modus. Two aspects were investigated: 1. The adequacy of combining observations from geostationary and Spot-V and Proba-V satellite missions for obtaining the target product; and, 2. The intercompatibility of ET estimates based on Spot-V and Proba-V so that continuous series over the operational period of both missions could be built. The comparison of simulated ET with in situ measured fluxes (eddy covariance) showed that the introduction of more spatial detail through polar-satellite observations resulted in the reduction of bias and root-mean-square error in ET estimates, as compared with estimations where Earth observation data were taken from geostationary satellites only. Moreover, the signals derived from Spot-V and Proba-V exhibited similarity during the period of operational overlap; especially in non-cultivated surfaces. This suggests that continuity objective of these two missions can be exploited in the estimation of ET time series. [ABSTRACT FROM AUTHOR]

Stresses acting on fault systems before major earthquakes can produce thermal anomalies; these abnormalities can be observed using multi-sensor satellite data. Moderate resolution spectro-radiometer on board the terra and aqua satellites can provide thermal infrared (TIR) imaging data for land and ocean. These TIR data have recorded short-lived thermal anomaly prior to major earthquakes. It is suggested by others that these electromagnetic (EM) phenomena relate to stress build up before earthquakes. The objective of this study is to find an association between spatial extent and temporal evolution of thermal anomalies and known major earthquakes near the boundary of Nazca plate and South American plate. Our approach is to map the TIR transient fields from polar orbiting satellites and analysing those data using time series temperature plots to detect the abnormal thermal trends before the earthquake. This study concentrated on marine earthquakes to detect the changes in both land and ocean before seismic activity. [ABSTRACT FROM AUTHOR]

The first global night-time light composite data from the Visible Infrared Imaging Radiometer Suite (VIIRS) day–night band carried by the Suomi National Polar-orbiting Partnership (NPP) satellite were released recently. So far, few studies have been conducted to assess the ability of NPP-VIIRS night-time light composite data to extract built-up urban areas. This letter aims to evaluate the potential of this new-generation night-time light data for extracting urban areas and compares the results with Defense Meteorological Satellite Program–Operational Linescan System (DMSP-OLS) data through a case study of 12 cities in China. The built-up urban areas of 12 cities are extracted from NPP-VIIRS and DMSP-OLS data by using statistical data from government as reference. The urban areas classified from Landsat 8 data are used as ground truth to evaluate the spatial accuracy. The results show the built-up urban areas extracted from NPP-VIIRS data have higher spatial accuracies than those from DMSP-OLS data for all the 12 cities. These improvements are due to the relatively high spatial resolution and wide radiometric detection range of NPP-VIIRS data. This study reveals that NPP-VIIRS night-time light composite data would provide a powerful tool for urban built-up area extraction at national or regional scale. [ABSTRACT FROM PUBLISHER]

The Memory Test Experiment is a space test of a ferroelectric memory device on a low Earth orbit satellite that launched in November 2010. The memory device being tested is a commercial Ramtron Inc. 512K memory device. The circuit was designed into the FASTSAT avionics and is not used to control the satellite. The test consists of writing and reading data with the ferroelectric based memory device. Any errors are detected and are stored on board the satellite. The data is sent to the ground through telemetry once a day. Analysis of the data can determine the kind of error that was found and will lead to a better understanding of the effects of space radiation on memory systems. The test is one of the first flight demonstrations of ferroelectric memory in a near polar orbit which allows testing in a varied radiation environment. The initial data from the test is presented. This paper details the goals and purpose of this experiment as well as the development process. The process for analyzing the data to gain the maximum understanding of the performance of the ferroelectric memory device is detailed. [ABSTRACT FROM AUTHOR]

To quantify the sampling error of wind speed (W) and the surface air specific humidity (Qa) resulting from Sun-synchronous polar-orbit satellite sampling and the effect of single- and multi-satellite sampling, we compared satellite-simulated data with true daily mean data using buoy data. True daily mean data were obtained by averaging buoy data at all available times over 24 h, while satellite-simulated data were the averages of buoy data sampled at satellite passing times (once or twice each day). The difference between true and satellite-simulated data was defined as the sampling error. The sampling error of the daily mean data of W and Qa depends considerably on the satellite observation time and location. Although the sampling error is fairly reduced if multi-satellite sampling is employed, a noticeable sampling error remains in some cases if a wrong sampling combination is employed. Therefore, multi-satellite data should be carefully used to obtain more accurate global data. [ABSTRACT FROM AUTHOR]

The north-south symmetry of the low level near-equatorial atmospheric flow is examined in relation to the position of the Intertropical Convergence Zone (ITCZ) over the Indian Ocean with the aid of satellite and reanalysis data. Absolute vorticity (AV) and convergence fields on temporal scales of 10 days are derived from 7 years of Quick Scatterometer (QuikSCAT) observations and related statistically to organized convection deduced from outgoing longwave radiation (OLR) measured by the National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites. The AV observations reveal a belt of symmetric instability on the summer side of the equator. The evolution of this symmetric instability with respect to the cross-equatorial flow (CEF), the location of the ITCZ, and monsoonal forcing is investigated. We identify three distinct dominant convective regimes. We show that during the active Indian monsoon season, symmetric instability and the displacement of the zero-AV line off the equator are directly linked to organized convection and the off-equatorial location of the ITCZ. The advective (inertial) regime interacts with and is controlled by monsoon and CEF. In periods of transition between summer and winter monsoon, the lower atmosphere is symmetrically stable and two other convective regimes can be identified: a double ITCZ, and localized convection near the equator. [ABSTRACT FROM AUTHOR]

Atmospheric gravity waves (AGWs) trapped in the marine boundary layer leave fingerprints on the ocean surface, which are detectable by Synthetic Aperture Radar (SAR) on board polar-orbiting satellites. They are associated with varying wind speeds on the sea surface, which modulate the small-scale sea surface roughness and thus the backscattered radar power. We present three representative examples of SAR images acquired over the South China Sea by the Advanced Synthetic Aperture Radar (ASAR) on board the European Envisat satellite and show that different mechanisms are responsible for their generation and trapping in a wave duct (wave guide). For this we use, in addition to the ASAR images, satellite images acquired around the same time in the visible and infrared channels by the US polar orbiting satellite Terra and the Japanese geostationary satellite Multifunctional Transport Satellite (MTSAT)-1R, and in the microwave band by the Quick Scatterometer (QuikSCAT) satellite. In addition, we use synoptic weather information from which parameters relating to the trapping of atmospheric gravity waves in the lower troposphere are derived. Furthermore, we extract quantitative information on the sea surface wind speed induced by AGWs based on a wind scatterometer model. [ABSTRACT FROM AUTHOR]

Polar orbiting meteorological satellites have been used successfully in many fields in which applications, such as dynamic monitoring, need multi-temporal remote sensing data imaged in the same region but at different times and with different sensors. The basis of these quantitative applications is automatic and synthetic preprocessing of different satellite data. In order to ensure the direct comparability of multi-source satellite National Oceanic & Atmospheric Administration-Advanced Very High Resolution Radiometer (NOAA-AVHRR) series and FY-1D 1A.5 data, based on its imaging mechanisms, the paper discusses radiant and geometric preprocessing methods used for visual and near-infrared and thermal infrared channels. This is performed by analysing the technical parameters of the satellites and the sensors, theoretical numerical simulation and image data comparison. For synthetic radiance preprocessing, radiance calibration, spectral calibration for different sensors and calibration of the Sun elevation angles or the satellite zenith angles at the imaging time are included. Based on normalization of spatial resolution in scan-line directions, rough geometric correction and precise registration are sequentially processed for geometric preprocessing with a higher precision. Combining the detailed steps introduced in the paper, automatic preprocessing of polar orbiting meteorological satellites can be realized. [ABSTRACT FROM AUTHOR]

For 6 months between April and October 2003, two identical scatterometers flew in tandem. Their observations demonstrate the need for more than one scatterometer in the polar orbit to include sufficient temporal variability and reduce aliasing of ocean surface wind-stress measurements required for applications such as estimating electricity generation potential and ocean-atmosphere gas exchange. The energy deficiency over a 12-h period, evident in the data from one scatterometer, is eliminated with the additional scatterometer. The missions in tandem allow an improved understanding of the diurnal variability from coastal regions to the open ocean. The power density distributions were found to be very different at the different sampling times of the two satellites. Two scatterometers will be launched by India and China in the next few years and will fly in tandem with the scatterometers of the USA and Europe, which are already in operation. The potential improvement in the coverage of ocean wind stress by this constellation is analysed and discussed. The constellation is found to meet the 6-hourly revisit requirement of operational weather forecasting over most of the ocean. [ABSTRACT FROM AUTHOR]

The article discusses various topics published within the issue including the analysis of ocean bottom pressure (OBP) data from the Gravity Recovery and Climate Experiment (GRACE), and another one about the use of two identical scattometer to demonstrate the need in polar orbit.

The forward radiative transfer routine has been used to remove the artefact caused by modulation on meteorological satellite-sensor responses. This paper describes a direct method where images observed by the infrared channels aboard the Multi-functional Transport Satellite (MTSAT-1R) and Fengyun-2C (FY-2C) geostationary satellites are compared with those by the Advanced Very High Resolution Radiometer (AVHRR) sensor aboard the National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites. The calibration differences between the polar orbiting and the geostationary satellites are found to be within 1 K of each other. [ABSTRACT FROM AUTHOR]

The detection of forest fires and the determination of their parameters have been usually carried out by polar-orbit sensors: AVHRR, (A)ATSR, BIRD, and MODIS mainly. However, their time resolution prevents them from operating in real time. In contrast, the new geostationary sensors have very appropriate capacities for the observation of the Earth and monitoring of forest fires, as is being proved. GOES, MSG, and MTSAT are already operative, and they have led the international community to think that the global observation network in real time may become a reality. The implementation of this network is the aim of the Global Observations of Forest Cover and Land Cover Dynamics (GOFC/GOLD) FIRE Mapping and Monitoring programme, focused internationally on taking decisions concerning the research of the Global Change. In this Letter, the operation in real time by the MSG-SEVIRI sensor over the Iberian Peninsula is studied. On the other hand, the reliability of validation results by means of polar sensors, with a finer spatial resolution, is difficult to analyse due to errors caused by confused location of fires. This Letter shows that fires detected by means of MSG-SEVIRI can be an useful option in order to estimate burnt areas at global scale, considering a spatial resolution of 40 km. [ABSTRACT FROM AUTHOR]

A new over–water dust detection algorithm is developed and applied to the 5–channel Advanced Very High Resolution Radiometer (AVHRR) imager onboard the National Oceanic and Atmospheric Administration series of polar orbiting satellites. The algorithm has been developed to improve the distinction between dust and meteorological clouds for very optically thick dust storms that would have previously been flagged as cloud under the Clouds from AVHRR Extended cloud mask algorithm. The algorithm has been assessed by making daily comparisons with data from the Aerosol Robotic Network and by making a climatological comparison with METEOSAT and Total Ozone Mapping Spectrometer data over a portion of the North Atlantic. The new algorithm improves the separation of clouds and airborne dust. Application of the new product to the 5–channel AVHRR historic data sets can provide information on the global dust signal, especially on an interannual time scale. [ABSTRACT FROM AUTHOR]

A study was carried out to estimate field-scale Leaf Area Index (LAI) using fine resolution polar orbiting IRS-1D LISS-III sensor data at 23 m spatial resolution. Three cloud-free scenes on 8 January, 2002 (D1), 30 January, 2002 (D2) and 15 January, 2003 (D3) over two sites in Gujarat, India, were acquired. The subscenes encompassing the study area were extracted and geo-registered. Surface reflectances in the red (0.62-0.68 µm) and near-infrared (NIR) (0.77-0.86 µm) bands were generated using 6S atmospheric correction code and coincident ground measurements on aerosol and water vapour. Normalized difference vegetation index (NDVI), simple ratio (SR) and soil-adjusted vegetation index (SAVI) were computed from the reflectances in the red and NIR. A total of 70 mean measured LAI datasets on wheat and tobacco were used for regression analysis and empirical models were developed between LAI and three vegetation indices (VI). Both exponential and power models gave R² between 0.53 and 0.61 except for D2 (R² between 0.04 and 0.11) when wheat was mostly at the post-anthesis stage and the VI-LAI relation seems to be influenced by canopy geometry and angular distribution of leaves. The analysis indicated that with the soil type of the study sites being different, the SAVI-based model had a smaller rms. error (R² = 0.496 and rms. error = 0.685) in estimation of LAI when compared with the SR- (R² = 0.478, rms. error = 0.698) and NDVI- (R² = 0.491, rms. error = 0.689) based models. The LAIs for the study region were estimated by inversion of empirical models and validated against ground-measured data. [ABSTRACT FROM AUTHOR]

Solar eclipses evident in short wavelength data sensed by polar orbiting Sun-synchronous wide field of view instruments such as SeaWiFS and POLDER are illustrated, and some implications for global dataset production are considered. [ABSTRACT FROM AUTHOR]

Mount Erebus (Antarctica) is a remote and inhospitable volcano, where field campaigns are possible only during the austral summer. In addition to continuously monitoring seismic instruments and video cameras, data from scanners flown aboard polar orbiting space-craft, such as the Thematic Mapper (TM) and Advanced Very High Resolution Radiometer (AVHRR), can contribute to continuous, year-round monitoring of this volcano. Together these data allow measurement of the temperature of, thermal and gas flux from, and mass flux to a persistently active lava lake at Erebus' summit. The monitoring potential of such polar-orbiting instruments is enhanced by the poleward convergence of sub-spacecraft ground-tracks at the Erebus latitudes, permitting more frequent return periods than at the equator. Ground-based observations show that the Erebus lava lake was active with an area of ~2800m2 and sulphur dioxide (SO2) flux of (230 +/- 90)td-1 prior to September 1984. AVHRR-based lake area and SO2 flux estimates are in good agreement with these measurements, giving (2320 +/- 1200)m2 and (190 +/- 100)td-1, respectively, during 1980. However during late-1984 the lava lake became buried, with TM data showing re-establishment of the lake, with a TM-derived surface temperature of 578-903 C, by January 1985. Following these events, ground-based lake area and SO2 flux measurements show that the lake area and SO2 flux was lower (180-630m2 and 9-91td-1, respectively). This is matched by a decline in the AVHRR- and TM-derived rate of magma supply to the lake from 330 167kgs-1 prior to 1984 to 30-76kgs-1 thereafter. Clearly, a reduction in magma supply to, and activity at, the lava lake occurred during 1984. We look forward to using data from such future polar-orbiting sensors as the Moderate Resolution Imaging Spectrometer (MODIS), Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER), Enhanced Thematic Mapper (ETM+) and Advanced Along Track Scanning Radiometer (AASTR) to contribute to high (once a day) temporal resolution measurement and monitoring of activity at this volcano. Such analyses will in turn contribute to a more complete understanding of how this volcano works. [ABSTRACT FROM AUTHOR]