Radiometer Satellite Data Research Articles

The 18 May 2024 Iberian superbolide from a sunskirting orbit: USG space sensors and ground-based independent observations

ABSTRACT On 18 May 2024, a superbolide traversed the western part of the Iberian Peninsula, culminating its flight over the Atlantic Ocean and generating significant media attention. This event was caused by a weak carbonaceous meteoroid of 1 m, entering the atmosphere at 40.4 km s$^{-1}$ with an average slope of 8.5$^\circ$. The luminous phase started at 133 km and ended at an altitude of 54 km. The meteoroid’s heliocentric orbit had an inclination of 16.4$^\circ$, a high eccentricity of 0.952, a semimajor axis of 2.4 au, and a short perihelion distance of 0.12 au. The superbolide was recorded by multiple ground-based stations of the Spanish Fireball and Meteorite Network and the European Space Agency, as well as by the U.S. Government sensors from space. Due to the absence of observable deceleration, we successfully reconciled satellite radiometric data with a purely dynamic atmospheric flight model, constraining the meteoroid’s mass and coherently fitting its velocity profile. Our analysis shows a good agreement with the radiant and velocity data reported by the Center for Near-Earth Object Studies, with a deviation of 0.56$^\circ$ and 0.1 km s$^{-1}$, respectively. The presence of detached fragments in the lower part of the luminous trajectory suggests that the meteoroid was a polymict carbonaceous chondrite, containing higher-strength macroscopic particles in its interior due to collisional gardening, or a thermally processed C-type asteroid. The orbital elements indicate that the most likely source is the Jupiter-Family Comet region, aligning with the Solar and Heliospheric Observatory comet family, as its sunskirting orbit is decoupled from Jupiter. This event provides important information to characterize the disruption mechanism of near-Sun objects.

A Radar-Based Hail Climatology of Australia

Abstract In Australia, hailstorms present considerable public safety and economic risks, where they are considered the most damaging natural hazard in terms of annual insured losses. Despite these impacts, the current climatological distribution of hailfall across the continent is still comparatively poorly understood. This study aims to supplement previous national hail climatologies, such as those based on environmental proxies or satellite radiometer data, with more direct radar-based hail observations. The heterogeneous and incomplete nature of the Australian radar network complicates this task and prompts the introduction of some novel methodological elements. We introduce an empirical correction technique to account for hail reflectivity biases at C band, derived by comparing overlapping C- and S-band observations. Furthermore, we demonstrate how object-based hail swath analysis may be used to produce resolution-invariant hail frequencies, and describe an interpolation method used to create a spatially continuous hail climatology. The maximum estimated size of hail (MESH) parameter is then applied to a mixture of over 50 operational radars in the Australian radar archive, resulting in the first nationwide, radar-based hail climatology. The spatiotemporal distribution of hailstorms is examined, including their physical characteristics, seasonal and diurnal frequency, and regional variations of such properties across the continent.

Evaluation of Arctic Sea Ice Drift Products Based on FY-3, HY-2, AMSR2, and SSMIS Radiometer Data

Different radiometer sensors have different frequencies, spatial resolutions, and time resolutions, which lead to inconsistencies in ice drift products retrieved by radiometer sensors. Based on the continuous maximum cross-correlation method, in this paper, we used China’s FY-3 and HY-2 satellite radiometer data to generate sea ice drift products; we further evaluated the consistency between them and sea ice drift products retrieved from AMSR2 and SSMIS satellite radiometer data, which could help in future retrieval accuracies of more radiometer sea ice drift products. The results show that ice drift products with good reliability can be obtained by retrievals using 37 and 89 GHz channels of FY-3 and HY-2 radiometer bright temperature data. Compared with the buoy data, the root mean square errors (RMSEs) of the 37 GHz HY-2 sea ice drift product (at an interval of 6 days) were 1.40 cm/s and 7.31° for speed and direction, respectively, and the relative errors (REs) were 5.78% and 6.44%, respectively. The RMSEs of the 37 GHz FY-3 sea ice drift product were 0.77 cm/s and 6.49° for speed and direction, respectively, and the REs were 4.38% and 9.23%, respectively. Moreover, comparisons between sea ice drift vectors derived from AMSR2 and SSMIS satellites showed good quantitative agreement.

Bentonite clay minerals mapping using ASTER and field mineralogical data: A case study from the eastern Rif belt, Morocco

Remote sensing and mineralogical data have been integrated to map the spatial distribution of bentonite clay minerals in the Zeghanghane area, located in the eastern Rif belt of Morocco. Numerous bentonite deposits of substantial economic potential are recognized in this region and their acceptability is still restricted. These clay minerals are directly derived from different weathering types of Neogene volcanic outcrops. For this purpose, different remote sensing processing techniques have been applied to the Advanced Spaceborne Thermal Emission and Reflection Radiometer satellite data, including Relative absorption band-depth, Minimum noise fraction, Pixel purity index, and ND visualization. The obtained results allowed identifying three clay minerals, namely kaolinite/smectite, illite, and montmorillonite which typically characterize the bentonite clay minerals. They are mainly concentrated in the Neogene volcanic massifs such as Gourougou, Tidiennit and Amjar. Field work, petrographic and X-ray diffraction analyses permitted the verification and validation of the obtained results. A new bentonite alteration zones have been discovered and the majority of pre-existing ore deposits have been confirmed. The established bentonite map will serve as a guide for future mining exploration in the Zeghanghane area.

New Gridded Product for the Total Columnar Atmospheric Water Vapor over Ocean Surface Constructed from Microwave Radiometer Satellite Data

Based on the optimal interpolation (OI) algorithm, a daily fusion product of high-resolution global ocean columnar atmospheric water vapor with a resolution of 0.25° was generated in this study from multisource remote sensing observations. The product covers the period from 2003 to 2018, and the data represent a fusion of microwave radiometer observations, including those from the Special Sensor Microwave Imager Sounder (SSMIS), WindSat, Advanced Microwave Scanning Radiometer for Earth Observing System sensor (AMSR-E), Advanced Microwave Scanning Radiometer 2 (AMSR2), and HY-2A microwave radiometer (MR). The accuracy of this water vapor fusion product was validated using radiosonde water vapor observations. The comparative results show that the overall mean deviation (Bias) is smaller than 0.6 mm; the root mean square error (RMSE) and standard deviation (SD) are better than 3 mm, and the mean absolute deviation (MAD) and correlation coefficient (R) are better than 2 mm and 0.98, respectively.

Integration of airborne geophysics and satellite imagery data for exploration targeting in porphyry Cu systems: Chahargonbad district, Iran

ABSTRACTThis study illustrates the application of a geometric average integration of aeromagnetic, radiometric and satellite imagery data over a region prone to Cu‐bearing mineralization at Chahargonbad area in Kerman province of Iran. Processing aeromagnetic, radiometric and Advanced Spaceborne Thermal Emission and Reflection Radiometer satellite data can provide exploratory insights about favourable zones in association with porphyry‐type ore occurrences, which can be synthesized through a combination of knowledge‐ and data‐driven approaches as a geometric average and be represented in a mineral prospectivity map. The existence of known deposits in a prospect region can facilitate the investigation of significant exploratory footprints extracted from airborne data by calculating each indicator layer's weight by plotting a prediction–area curve accompanied by a concentration–area fractal curve. Among various indicators, the most important ones are determined based on derived weights from the prediction–area plots to be synthesized in a single Cu favorability map. To fulfil this aim, indicator layers from airborne geophysics (magmatic bodies, magnetic lineaments and potassium radiometry) and remote‐sensing data (alterations such as argillic, phyllic, propylitic and iron oxide along with geological lineaments) were prepared and evaluated using the known porphyry Cu mineralization by the simultaneous plot of the concentration–area fractal model and the prediction–area curve to attain the ore prediction rate and the relevant occupied area of each map for weight assignment of indicators. The geometric average prospectivity model was applied to synthesize the leading indicators, and the result was compared with a multi‐class index overlay map. This study's significance lies in improvement of the performance of the mineral prospectivity/potential mapping after running a geometric average by a higher ore prediction rate of 79%, which has occupied 21% of the area as potential zones for further mining investigations.

GeoColor: A Blending Technique for Satellite Imagery

AbstractValue-added imagery is a useful means of communicating multispectral environmental satellite radiometer data to the human analyst. The most effective techniques strike a balance between science and art. The science side requires engineering physical algorithms capable of distilling the complex scene into a reduced set of key parameters. The artistic side involves design and construction of visually intuitive displays that maximize information content within the product image. The utility of such imagery to human analysts depends on the extent to which parameters or features of interest are conveyed unambiguously. Here, we detail and demonstrate a dynamic blended imagery technique, based on spatially variant transparency factors whose values are tied to algorithmically isolated parameters. The technique enables seamless display of multivariate information, and is applicable to any imaging system based on red–green–blue composites. We illustrate this technique in the context of GeoColor—an application of the Geostationary Operational Environmental Satellite R (GOES-R) series Advanced Baseline Imager (ABI) supporting operational forecasting and used widely in public communication of weather information.

Testing the method for increasing the spatial resolution of satellite radiometric images in the L-band

The results of testing a method for increasing the spatial resolution of satellite radiometric data in the L-band are presented. Data obtained by satellite-borne radiometer is characterized by low spatial resolution. The use of satellite radar data can increase the spatial resolution of radiometric images in the L-band to hundreds of meters. At the moment, the L-band radiometric data processing is possible with the use of radar data C-band. For this reason the method gives satisfactory results in the absence of cloudiness on the radar image.

Consistency of Radiometric Satellite Data over Lakes and Coastal Waters with Local Field Measurements

The Sentinel-3 mission launched its first satellite Sentinel-3A in 2016 to be followed by Sentinel-3B and Sentinel-3C to provide long-term operational measurements over Earth. Sentinel-3A and 3B are in full operational status, allowing global coverage in less than two days, usable to monitor optical water quality and provide data for environmental studies. However, due to limited ground truth data, the product quality has not yet been analyzed in detail with the fiducial reference measurement (FRM) dataset. Here, we use the fully characterized ground truth FRM dataset for validating Sentinel-3A Ocean and Land Colour Instrument (OLCI) radiometric products over optically complex Estonian inland waters and Baltic Sea coastal areas. As consistency between satellite and local data depends on uncertainty in field measurements, filtering of the in situ data has been made based on the uncertainty for the final comparison. We have compared various atmospheric correction methods and found POLYMER (POLYnomial-based algorithm applied to MERIS) to be most suitable for optically complex waters under study in terms of product accuracy, amount of usable data and also being least influenced by the adjacency effect.

Comparison of sea ice classification methods based on satellite scatterometer and radiometer data in the Weddell Sea, Antarctica

AbstractInformation on sea ice type is an important factor for deriving sea ice parameters from satellite remote sensing data, such as sea ice concentration, extent and thickness. In this study, sea ice in the Weddell Sea was classified by the histogram threshold (HT) method, the Spreen model (SM) method from satellite scatterometer data and the strong contrast (SC) method from radiometer data, and this information was compared with Antarctic Sea Ice Processes and Climate (ASPeCt) sea ice-type ship-based observations. The results show that all three methods can distinguish the multi-year (MY) ice and first-year (FY) ice using Ku-band scatterometer data and radiometer data during the ice growth season, while C-band scatterometer data are not suitable for MY ice and FY ice discrimination using HT and SM methods. The SM model has a smaller MY ice classification extent than the HT method from scatterometer data. The classification accuracy of the SM method is the higher compared to ship-based observations. It can be concluded that the SM method is a promising method for discriminating MY ice from FY ice. These results provide a reference for further retrieval of long-term sea ice-type information for the whole of Antarctica.

Mapping of bauxite mineral deposits in the northern region of Saudi Arabia by using Advanced Spaceborne Thermal Emission and Reflection Radiometer satellite data

ABSTRACTMineral deposit mapping is very essential for sustainable and eco-friendly exploitation of natural resources. The Kingdom of Saudi Arabia has abundant natural resources such as natural gas, oil and minerals. It reserves high quantity of minerals such as phosphates, bauxites, copper, gold and other industrial minerals. The red soil regions located in Hail and Qassim provinces of Saudi Arabia have rich amount of bauxite (major aluminum ore) deposits. In order to initiate the focus on mapping of mineral deposits along this area, standardized hyper-spectral analysis has been carried out by using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data. The spectral signature of gibbsite (major element in bauxite) samples is analyzed with reference to the spectral features of gibbsite in the visible near infrared and short-wave infrared bands electromagnetic spectrum. Advanced hyper-spectral transformations such as minimum noise fraction function and pixel purity index have been performed to identify the target end-member. The existence of the mineral is confirmed by comparing the spectral signatures of the end-member with the predefined spectral plots of ASTER and United States Geological Survey spectral libraries. Finally, the end-members are mapped and their abundance is estimated in 0–1 scale. The study has opened up new areas for mapping of bauxite deposits in the area and leads to eco-friendly exploitation of natural resources. It also validates the high potential of ASTER multispectral satellite data for the exploration and mapping of mineral resources.

Semidiurnal frequency of the fields of the Arctic ice rarefaction and compression from the MTVZA-GYa satellite radiometer data

The spatiotemporal variability is considered ofthe field of ice rarefaction and compression in the Arctic due to the passage of semidiurnal tidal waves. A simplified method is developed for identification of such fields on the maps of the scattering index (SI) of ice computed from the MTVZA-GYa radiometer data. It is demonstrated that the low and high values of ice SI are ob served at tidal rarefactions and compressions, respectively. The analysis of the maps of extreme values of SI observed in overlapping semidiurnal and diurnal MTVZA-GYa measurements corroborated the existence of semidiurnal periodicity of alternating fields of the Arctic ice rarefaction and compression and revealed no variability in ice SI in the areas where tidal wave phases converge (there the convergence amplitude is minimum).

A review of differential absorption algorithms utilized at NOAA for measuring sea surface temperature with satellite radiometers

Abstract In a 1988 study, a generalized non-linear SST algorithm was derived from the radiative transfer equation. An empirical approximation to this algorithm provided the simplified NLSST algorithm for computing sea surface temperatures with satellite radiometer data. It has remained a favorite of the remote sensing community for the past 25 years. However, a 1998 study demonstrated that the functional form of the generalized non-linear algorithm, which is here designated the GNLSST, is very much data dependent. In this paper we explore the various functional forms that the GNLSST may take. Rather than using actual satellite data, we model the effects of atmospheric absorption by water vapor, under saturation conditions, on the satellite split-window temperature difference, ΔT, in the 11–13 μm infra-red spectral region. The parameters used in the GNLSST algorithm are adjusted to demonstrate the various forms that the GNLSST can take. One key finding is that the familiar algorithms used for measuring SST, such as the MCSST, the NLSST and the QSST are all special solutions to the more general GNLSST algorithm. Additionally, the GNLSST may take other forms, which are described graphically. The simplifying assumptions which yield the NLSST solution represent an approximation to reality when working with actual satellite data. It is demonstrated that minor modifications to the regression procedures, which are used to derive the NLSST with satellite split-window data, may reduce the temperature errors resulting from these approximations. Alternative forms of the GNLSST algorithm may be useful for users of regional split-window satellite data.

An assessment of land-use/land-cover change of Bistrishko branishte biosphere reserve using Landsat data

Land-Use/Land-Cover (LU/LC) change detection using satellite data has gained momentum with the advance of the pre-operational phase of regional and global earth observation programmes such as GEOS, GMES, and GOFC-GOLD to name but a few. Present study aims at revealing LU/LC change of Bistrishko branishte biosphere reserve using Landsat 5 TM and Landsat 7 ETM+ radiometer satellite data. The LU/LC classification of the study area is done for the period 2007-2012, and difference images, between LU/LC maps, have been created. The classification scheme follows CORINE2000 Level 3 with few additional classes introduced to map changes. The methods used in the study are geoinformation, cartography, and statistical. The results show that in effect of 2012 wildfire 0.72 km2 from reserve territory was devastated. The temporal changes which are taking place after the 60 ha windthrow in 2001, the 200 ha bark-beetle outbreak in 2003–2011 and the wildfire from June 2012 were further investigated using ASD HH FS spectrometer in 2011. As a result the increase in '331 Broad-leaved forest' and '312 Coniferous forest' LU/LC classes is attributed to the increase of the territory of deciduous species after a large bark beetle outbreak, which took place between 2003 and 2011, which devastated most of the old Picea abies trees, while the decrease of 'Outbreak' and '332 Bare rock' LU/LC classes is mainly due to the wildfire which took place in June 2012.

Deterioration of perennial sea ice in the Beaufort Gyre from 2003 to 2012 and its impact on the oceanic freshwater cycle

AbstractTime series of ice draft from 2003 to 2012 from moored sonar data are used to investigate variability and describe the reduction of the perennial sea ice cover in the Beaufort Gyre (BG), culminating in the extreme minimum in 2012. Negative trends in median ice drafts and most ice fractions are observed, while open water and thinnest ice fractions (<0.3 m) have increased, attesting to the ablation or removal of the older sea ice from the BG over the 9 year period. Monthly anomalies indicate a shift occurred toward thinner ice after 2007, in which the thicker ice evident at the northern stations was reduced. Differences in the ice characteristics between all of the stations also diminished, so that the ice cover throughout the region became statistically homogenous. The moored data are used in a relationship with satellite radiometer data to estimate ice volume changes throughout the BG. Summer solid fresh water content decreased drastically in consecutive years from 730 km3 in 2006 to 570 km3 in 2007, and to 240 km3 in 2008. After a short rebound, solid fresh water fell below 220 km3 in 2012. Meanwhile, hydrographic data indicate that liquid fresh water in the BG in summer increased 5410 km3 from 2003 to 2010 and decreased at least 210 km3 by 2012. The reduction of both solid and liquid fresh water components indicates a net export of approximately 320 km3 of fresh water from the region occurred between 2010 and 2012, suggesting that the anticyclonic atmosphere‐ocean circulation has weakened.

WindSat Radio-Frequency Interference Signature and Its Identification Over Greenland and Antarctic

A detection of radio-frequency interference (RFI) in the space-borne microwave radiometer data is difficult under snow and sea ice-covered conditions. The existing methods such as a spectral difference technique or a principal component analysis (PCA) of RFI indices produce many false RFI signals near the boundary of Greenland and Antarctic ice sheets. In this paper, a double PCA (DPCA) method is developed for RFI detection over Greenland and Antarctic regions. It is shown that the new DPCA method is effective in detecting RFI signals in the C- and X-band radiometer channels of WindSat while removing the false RFI signals over Greenland and Antarctic. It also worked well in other snow-free or snow-rich regions such as winter data over the United States. The proposed DPCA can be applied to satellite radiometer data orbit-by-orbit or granule-by-granule and is thus applicable in an operational environment for fast processing and data dissemination.

Microzooplankton grazing in the oceans: impacts, data variability, knowledge gaps and future directions

Here we review all published data on phytoplankton growth and microzooplankton grazing using the dilution technique to better understand the role of this group of grazers in different regions of the oceans, and to identify the knowledge gaps that require future efforts. A total of 1525 data points assimilated from 110 studies were included and grouped using the biogeographic subsets defined by Longhurst et al. [(1995) An estimate of global primary production in the ocean from satellite radiometer data. J. Plankton Res., 17, 1245–1271]. Total median phytoplankton growth rates in each of the subsets varied between 0.15 (Polar Southern) and 0.83 day−1 (Trades Atlantic), with the corresponding microzooplankton grazing rates ranging between 0.07 (Polar Southern) and 0.48 day−1 (Trades Indian). The median percentage of primary production (PP) grazed by microzooplankton was relatively constant among the regions and ranged from 49 to 77%, with the lowest percentage found in the Westerlies Southern and the highest in the Coastal Indian. Despite strong evidence that microzooplankton grazing impacts were highly variable, no global drivers for this variability (temperature, chlorophyll concentration) were identified in the analysis. As a global carbon budget, the overall consumption of phytoplankton for all regions was 31.3 Gt C year−1, which accounted for 62.4% of the total PP grazed daily. The amount of carbon ingested by micro- and mesozooplankton varied proportionally to the PP and the consumption was five times higher for micro- than for mesozooplankton. As concluding remarks of the study, we present some suggestions that may improve the quality of the data obtained with the dilution technique.

Observation of eddy structures in the Baltic Sea with the use of radiolocation and radiometric satellite data

The manifestations of mesoscale and submesoscale eddy elements in surface currents of the Baltic Sea in satellite images differing in physical nature and spatial resolution are considered. The investigation is based on the Envisat ASAR and ERS-2 SAR high-resolution radiolocation images (RLIs) obtained in 2008–2009 for different sites of the Baltic Sea water area and the use of the Envisat MERIS and Landsat ETM+ radiometric images of the visible spectrum. Possible mechanisms of the appearance of eddy structures in RLIs of the Baltic Sea water area are considered. Joint analysis of the mentioned data revealed specific features of the appearance of eddy structures in satellite images, taking into account the variability of optical characteristics of Baltic Sea surface waters during the summer blooming of cyanobacteria and the spring blooming of diatomic algae.

Identification of the age and compression areas of sea ice from the AMSU satellite microwave radiometer data

A physical substantiation of the new quantitative index of sea ice scattering (Bukharov index) computed from the all-weather AMSU satellite radiometer data is considered. A high sensitivity of the scattering index to the age, thickness, and hummocking of ice in the areas of its compression is demonstrated. The daily maps of the sea ice scattering index in the Arctic are plotted. The analysis of maps enabled to reveal a new phenomenon, a steady existence of various-scale areas of short-range deformations of the sea ice in the Arctic. A new technique is proposed of the identification of age, relative thickness, and compression areas of ice using the maps of minimum and maximum values of the scattering index.

A Time-Varying Radiometric Bias Correction for the TRMM Microwave Imager

Recent intersatellite radiometric comparisons of the Tropical Rainfall Measurement Mission Microwave Imager (TMI) with polar orbiting satellite radiometer data and modeled clear-sky radiances have uncovered a time-variable radiometric bias in the TMI brightness temperatures. The bias is consistent with a source that generally cools during orbit night and warms during sunlight exposure. The likely primary source has been identified as a slightly emissive parabolic antenna reflector. This paper presents an empirical brightness temperature correction to TMI based on the position around each orbit and the Sun elevation above the orbit plane. The results of radiometric intercomparisons with WindSat and special sensor microwave imager are presented, which demonstrate the effectiveness of the recommended correction approach based on four years of data.