Future Satellite Research Articles

4D-Var Inversion of European NH3 Emissions Using CrIS NH3 Measurements and GEOS-Chem Adjoint With Bi-Directional and Uni-Directional Flux Schemes.

We conduct the first 4D‐Var inversion of NH3 accounting for NH3 bi‐directional flux, using CrIS satellite NH3 observations over Europe in 2016. We find posterior NH3 emissions peak more in springtime than prior emissions at continental to national scales, and annually they are generally smaller than the prior emissions over central Europe, but larger over most of the rest of Europe. Annual posterior anthropogenic NH3 emissions for 25 European Union members (EU25) are 25% higher than the prior emissions and very close (<2% difference) to other inventories. Our posterior annual anthropogenic emissions for EU25, the UK, the Netherlands, and Switzerland are generally 10%–20% smaller than when treating NH3 fluxes as uni‐directional emissions, while the monthly regional difference can be up to 34% (Switzerland in July). Compared to monthly mean in‐situ observations, our posterior NH3 emissions from both schemes generally improve the magnitude and seasonality of simulated surface NH3 and bulk NH x wet deposition throughout most of Europe, whereas evaluation against hourly measurements at a background site shows the bi‐directional scheme better captures observed diurnal variability of surface NH3. This contrast highlights the need for accurately simulating diurnal variability of NH3 in assimilation of sun‐synchronous observations and also the potential value of future geostationary satellite observations. Overall, our top‐down ammonia emissions can help to examine the effectiveness of air pollution control policies to facilitate future air pollution management, as well as helping us understand the uncertainty in top‐down NH3 emissions estimates associated with treatment of NH3 surface exchange.

Investigation of a Relation between Radiogenic Heat Production Rate (RHPR) and Land Surface Heat Temperature (LST) from Thermal Bands of ASTER and Landsat-8 (TIR-Data): Case Study of West Ras Gharib area North Eastern Desert, Egypt

In this paper, an attempt was tried to study the relation between the land surface heat temperature (LST), extracted, from the thermal emission infrared data (ASTER-TIR) and (Landsat-8-TIR) imagery and radiogenic heat production rate (RHPR) that calculated from airborne gamma-ray spectrometric data applied on west Ras Gharib area at Northeastern Desert of Egypt. The area is geologically covered mainly by Precambrian basement rocks, which are unconformably overlain by Phanerozoic sedimentary succession. The method used for extraction land surface heat temperature for both ASTER-TIR and Landsat-8-TIR images is the reference channel emissivity technique and founded as the best method comparing to others. The study results showed a relative higher RHPR threshold value reached 4.8 μW/m3. On the other hand, ASTER-TIR Land Surface Temperature (AST-LST) ranges between 27.64oC to 47.2oC and, the Landsat 8-TIR Land Surface Temperature (LS8-LST) ranges between 30.64oC to 50.68oC. Comparing all results, there were a weak relationship or to some extent parallel relation between RHPR and satellite LST; as when the value of the Y-axis is constant, there are multiple values on X-axis, so it is not possible to deduce the value of one variable in terms of the other. The poor relation is regarded to the very weak RHPR which is not enough to affect the surface heat temperature, emission that could be detected by both thermal sensors of ASTER and Landsat-8 satellite TIR data. Other factors such as: topography, wind, shading and scattering, rock moisture and density, can strongly affect the surface temperature. In conclusion, the output results could be improved in areas of very high radioelement concentrations especially 235U, and through the use of the enhanced spatial resolution of future satellite TIR imaging instruments.

Diurnal variability of rain and rain-induced propagation impacts at a tropical location: A seasonal comparison

The knowledge of diurnal cycle of rainfall (DCR), is crucial for meticulous understanding of the rain climatology, and thus quite imperative for devising precise rainfall forecasting models which is important for future satellite communication channel modelling. The location of Kolkata is characterized by stratiform, convective as well as mixed type of rainfall during different seasons of the year. The rain diversity prevailing over Kolkata, located at the verge of the tropics, prompts critical investigation of rain and rain-induced impairments. The present study utilizes 4 years data of ground-based observations over Kolkata. The present study not only highlights significant features of DCR during the pre-monsoon and the monsoon days but also indicates the distinct variability of rain-induced propagation impairments associated with the rain drop size distribution pattern.

Topology design algorithm for optical inter-satellite links in future navigation satellite networks

Topology design algorithm for optical inter-satellite links in future navigation satellite networks

Hyperspectral reflectance spectra of floating matters derived from Hyperspectral Imager for the Coastal Ocean (HICO) observations

Abstract. Using data collected by the Hyperspectral Imager for the Coastal Ocean (HICO) on the International Space Station between 2010–2014, hyperspectral reflectance spectra of various floating matters in global oceans and lakes are derived for the spectral range of 400–800 nm. Specifically, the entire HICO archive of 9411 scenes is first visually inspected to identify suspicious image slicks. Then, a nearest-neighbor atmospheric correction is used to derive surface reflectance of slick pixels. Finally, a spectral unmixing scheme is used to derive the reflectance spectra of floating matters. Analysis of the spectral shapes of these various floating matters (macroalgae, microalgae, organic particles, whitecaps) through the use of a spectral angle mapper (SAM) index indicates that they can mostly be distinguished from each other without the need for ancillary information. Such reflectance spectra from the consistent 90 m resolution HICO observations are expected to provide spectral endmembers to differentiate and quantify the various floating matters from existing multi-band satellite sensors and future hyperspectral satellite missions such as NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission; Geosynchronous Littoral Imaging and Monitoring Radiometer (GLIMR) mission; and Surface Biology and Geology (SBG) mission. All spectral data are available at https://doi.org/10.21232/74LvC3Kr (Hu, 2021b).

Large CO2 Emitters as Seen From Satellite: Comparison to a Gridded Global Emission Inventory.

Using the multiyear archive of the two Orbiting Carbon Observatories (OCO) of NASA, we have retrieved large fossil fuel CO2 emissions (larger than 1.0 ktCO2 h−1 per 10−2 square degree grid cell) over the globe with a simple plume cross‐sectional inversion approach. We have compared our results with a global gridded and hourly inventory. The corresponding OCO emission retrievals explain more than one third of the inventory variance at the corresponding cells and hours. We have binned the data at diverse time scales from the year (with OCO‐2) to the average morning and afternoon (with OCO‐3). We see consistent variations of the median emissions, indicating that the retrieval‐inventory differences (with standard deviations of a few tens of percent) are mostly random and that trends can be calculated robustly in areas of favorable observing conditions, when the future satellite CO2 imagers provide an order of magnitude more data.

Past, Present and Future Marine Microwave Satellite Missions in China

Over the past 60 years, China has made fruitful achievements in the field of ocean microwave remote sensing satellite technology. A long-term plan has now been formulated for the development of Chinese ocean satellites, as well as the construction of a constellation of ocean dynamic environmental and ocean surveillance satellites. These will gradually form China’s ocean monitoring network from space, thereby playing important roles in future ocean resource and environmental monitoring, marine disaster prevention and reduction, and global climate change. In this review manuscript, the developmental history of ocean microwave satellites and the development status of oceanic microwave remote sensing satellites in China are reviewed. In addition, China’s achievements in the field of oceanic microwave remote sensing satellite technology are summarized, and the future development of China’s ocean microwave remote sensing satellite program is analysed.

Fast infrared radiative transfer calculations using graphics processing units: JURASSIC-GPU v2.0

Abstract. Remote sensing observations in the mid-infrared spectral region (4–15 µm) play a key role in monitoring the composition of the Earth's atmosphere. Mid-infrared spectral measurements from satellite, aircraft, balloons, and ground-based instruments provide information on pressure, temperature, trace gases, aerosols, and clouds. As state-of-the-art instruments deliver a vast amount of data on a global scale, their analysis may require advanced methods and high-performance computing capacities for data processing. A large amount of computing time is usually spent on evaluating the radiative transfer equation. Line-by-line calculations of infrared radiative transfer are considered to be the most accurate, but they are also the most time-consuming. Here, we discuss the emissivity growth approximation (EGA), which can accelerate infrared radiative transfer calculations by several orders of magnitude compared with line-by-line calculations. As future satellite missions will likely depend on exascale computing systems to process their observational data in due time, we think that the utilization of graphical processing units (GPUs) for the radiative transfer calculations and satellite retrievals is a logical next step in further accelerating and improving the efficiency of data processing. Focusing on the EGA method, we first discuss the implementation of infrared radiative transfer calculations on GPU-based computing systems in detail. Second, we discuss distinct features of our implementation of the EGA method, in particular regarding the memory needs, performance, and scalability, on state-of-the-art GPU systems. As we found our implementation to perform about an order of magnitude more energy-efficient on GPU-accelerated architectures compared to CPU, we conclude that our approach provides various future opportunities for this high-throughput problem.

Satellite Observations Reveal a Large CO Emission Discrepancy From Industrial Point Sources Over China

AbstractIrregular industrial Carbon monoxide (CO) emissions not only deteriorate global atmospheric environment but also add a large uncertainty to CO emission inventory. This work demonstrates the potentiality of the Tropospheric Monitoring Instrument (TROPOMI) data product to derive CO emissions from facility‐level industrial sources. We have demonstrated CO emission estimates of 14 randomly selected facility‐level industrial sources over China with uncertainties of 10%–35% from TROPOMI archive between 2017 and 2020. We found that most of the plumes reveal significantly larger emissions than the registered inventory values. The simplicity of the demonstrated plume quantification method makes it easily applicable everywhere around the globe. This study suggests that future CO satellite constellation can routinely observe point source CO emissions to support environment policy.

An Idealized 1½-Layer Isentropic Model with Convection and Precipitation for Satellite Data Assimilation Research. Part I: Model Dynamics

Abstract An isentropic 1½-layer model based on modified shallow-water equations is presented, including terms mimicking convection and precipitation. This model is an updated version of the isopycnal single-layer modified rotating shallow water (modRSW) model. The clearer link between fluid temperature and model variables together with a double-layer structure make this revised, isentropic model a more suitable tool to achieve our future goal: to conduct idealized experiments for investigating satellite data assimilation. The numerical model implementation is verified against an analytical solution for stationary waves in a rotating fluid, based on Shrira’s methodology for the isopycnal case. Recovery of the equivalent isopycnal model is also verified, both analytically and numerically. With convection and precipitation added, we show how complex model dynamics can be achieved exploiting rotation and relaxation to a meridional jet in a periodic domain. This solution represents a useful reference simulation or “truth” in conducting future (satellite) data assimilation experiments, with additional atmospheric conditions and data. A formal analytical derivation of the isentropic 1½-layer model from an isentropic two-layer model without convection and precipitation is shown in a companion paper (Part II).

Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB E-mode and μ-distortion anisotropies

ABSTRACT Multifield inflation models and non-Bunch–Davies vacuum initial conditions both predict sizeable non-Gaussian primordial perturbations and anisotropic μ-type spectral distortions of the cosmic microwave background (CMB) blackbody. While CMB anisotropies allow us to probe non-Gaussianity at wavenumbers $k\simeq 0.05\, {\rm Mpc^{-1}}$, μ-distortion anisotropies are related to non-Gaussianity of primordial perturbation modes with much larger wavenumbers, $k\simeq 740\, {\rm Mpc^{-1}}$. Through cross-correlations between CMB and μ-distortion anisotropies, one can therefore shed light on the aforementioned inflation models. We investigate the ability of a future CMB satellite imager like LiteBIRD to measure μT and μE cross-power spectra between anisotropic μ-distortions and CMB temperature and E-mode polarization anisotropies in the presence of foregrounds, and derive LiteBIRD forecasts on ${f_{\rm NL}^\mu (k\simeq 740\, {\rm Mpc^{-1}})}$. We show that μE cross-correlations with CMB polarization provide more constraining power on $f_{\rm NL}^\mu$ than μT cross-correlations in the presence of foregrounds, and the joint combination of μT and μE observables adds further leverage to the detection of small-scale primordial non-Gaussianity. For multifield inflation, we find that LiteBIRD would detect ${f_{\rm NL}^\mu }=4500$ at 5σ significance after foreground removal, and achieve a minimum error of ${\sigma (f_{\rm NL}^\mu =0) \simeq 800}$ at 68 per cent CL by combining CMB temperature and polarization. Due to the huge dynamic range of wavenumbers between CMB and μ-distortion anisotropies, such large $f^\mu _{\rm NL}$ values would still be consistent with current CMB constraints in the case of very mild scale dependence of primordial non-Gaussianity. Anisotropic spectral distortions thus provide a new path, complementary to CMB B-modes, to probe inflation with LiteBIRD.

Dynamic verification of satellite systems using Ilities

The research outlines the design for an ‘ilities tool’ to assist small satellite verification. Prior literature commonly requests for ilities to be built-in to small satellite systems to prevent failure. Test standards are reviewed to define critical ilities. Definitions are then used to develop calculations that system designers can automate with a software tool . Previous failure data are used to predict the reliability of a future small satellite system. Bayesian estimation is applied to a qualitative NASA database of 219 small satellite (0.001–180 kg) failures from 2000 to 2016 to generate eight failure categories. A communication system (47%) or the attitude control (16%) failure are most likely to occur. A failure in the communication system has a low chance of survivability (16%). A failure within the attitude control system is expected to end with partial mission success (54%). The research suggests that an ilities tool can contribute to dynamically aiding verification. Such a tool will complement small satellite verification methods currently described by testing standards.

A Broadband View of the Sea Surface Height Wavenumber Spectrum.

Airborne lidar altimetry can measure the sea surface height (SSH) over scales ranging from hundreds of kilometers to a few meters. Here, we analyze the spectrum of SSH observations collected during an airborne lidar campaign conducted off the California coast. We show that the variance in the surface wave band can be over 20 times larger than the variance at submesoscales and that the observed SSH variability is sensitive to the directionality of surface waves. Our results support the hypothesis that there is a spectral gap between meso‐to‐submesoscale motions and small‐scale surface waves and also indicate that aliasing of surface waves into lower wavenumbers may complicate the interpretation of SSH spectra. These results highlight the importance of better understanding the contributions of different physics to the SSH variability and considering the SSH spectrum as a continuum in the context of future satellite altimetry missions.

Remote Sensing of Tundra Ecosystems Using High Spectral Resolution Reflectance: Opportunities and Challenges

AbstractObserving the environment in the vast regions of Earth through remote sensing platforms provides the tools to measure ecological dynamics. The Arctic tundra biome, one of the largest inaccessible terrestrial biomes on Earth, requires remote sensing across multiple spatial and temporal scales, from towers to satellites, particularly those equipped for imaging spectroscopy (IS). We describe a rationale for using IS derived from advances in our understanding of Arctic tundra vegetation communities and their interaction with the environment. To best leverage ongoing and forthcoming IS resources, including National Aeronautics and Space Administration’s Surface Biology and Geology mission, we identify a series of opportunities and challenges based on intrinsic spectral dimensionality analysis and a review of current data and literature that illustrates the unique attributes of the Arctic tundra biome. These opportunities and challenges include thematic vegetation mapping, complicated by low‐stature plants and very fine‐scale surface composition heterogeneity; development of scalable algorithms for retrieval of canopy and leaf traits; nuanced variation in vegetation growth and composition that complicates detection of long‐term trends; and rapid phenological changes across brief growing seasons that may go undetected due to low revisit frequency or be obscured by snow cover and clouds. We recommend improvements to future field campaigns and satellite missions, advocating for research that combines multi‐scale spectroscopy, from lab studies to satellites that enable frequent and continuous long‐term monitoring, to inform statistical and biophysical approaches to model vegetation dynamics.

The Short‐Time Prediction of the Energetic Electron Flux in the Planetary Radiation Belt Based on Stacking Ensemble‐Learning Algorithm

AbstractHigh energy electrons in planetary radiation belts are a major threat to satellites and communications in deep space applications. In order to predict the variations of energetic electron fluxes for different energy channels, we proposed a new ensemble machine leaning model for differential electron flux from 30 keV to 4 MeV in the Earth's radiation belts based on the RBSP‐A observation data from March 2013 to December 2017. The deep neural network (DNN), the convolutional neural network (CNN), the combination of CNN and DNN (CNN&amp;DNN), the linear regression (LR), and the light gradient boosting machine (LightGBM) are among the machine learning models chosen. We carefully compared the electron flux predictions for 20 energy levels and all five models can present valid short‐time flux forecasts. The DNN model has the poorest result. The LR model is good for short‐term forecasting but not so good for long‐term forecasting. The LightGBM ensemble model is highly stable, and it has always outperformed other independent models in terms of forecast accuracy. Then the comparison by adding AE and SYM‐H indexes is given and the influence of geomagnetic activity conditions can be negligible for this short‐time prediction. Furthermore, we applied these five models on Saturn and finally got very similar prediction results. Our results will be significantly useful in instrument designs and system control of future scientific satellites in deep space explorations.

Identification of limiting damping mechanisms in a high quality factor hybrid resonator of space application gyroscope

• Studied hybrid gyroscope resonator damping mechanisms with imperfection sensitivity. • Realized thin film coated high precision resonator with few millions quality factor. • Limiting damping mechanisms are identified at each stage from design to realization. The performance of Hemispherical Resonator Gyroscopes (HRG) is decided by the mechanical resonator’s Quality factor ( Q factor). The Q factor is a measure of energy dissipation. A Q factor of few millions is needed to realize fine resolution millimeter size of the HRG for future interplanetary satellite missions. The objective is to carry out a detailed study of thermoelastic damping (TED), anchor loss, surface loss, material internal friction and fluid damping. A hybrid resonator is designed with very low TED. One of the major contributions of the present work is the study of the effect of thin film coating and different coating configurations on TED. Extensive simulations have been carried out on the effect of different fabrication deviations on anchor loss. A unique sensitivity study of mode interactions and mass unbalance pattern on frequency split and anchor loss mismatch is also done. Based on this, dimensional and geometric tolerances are derived for precision fabrication and the precision hybrid configuration resonator is realized. Surface loss and material internal friction are estimated. Also, surface characterisation has been done using nanoindentation techniques. Q factor of few millions is obtained in a fabricated precision resonator with thin film coating. Based on the estimation of different damping mechanisms and measurements, the limiting mechanisms are identified at each stage from the design to the realization. The Q factor of an uncoated resonator is limited by the surface loss while that of a coated resonator is limited by the coating induced additional TED, the coating material internal friction and the surface loss.

The Boundary Layer Air Quality-Analysis Using Network of Instruments (BAQUNIN) Supersite for Atmospheric Research and Satellite Validation over Rome Area

Abstract The Boundary layer Air Quality-analysis Using Network of Instruments (BAQUNIN) supersite is presented. The site has been collecting pollutant concentrations and meteorological parameters since 2017. Currently, BAQUNIN consists of three observation sites located in the city center of Rome (Italy), and in the neighboring semirural and rural areas. To the best of our knowledge, BAQUNIN is one of the first observatories in the world to involve several passive and active ground-based instruments installed in multiple locations, managed by different research institutions, in a highly polluted megacity affected by coastal weather regimes. BAQUNIN has been promoted by the European Space Agency to establish an experimental research infrastructure for the validation of present and future satellite atmospheric products and the in-depth investigation of the planetary and urban boundary layers. Here, the main characteristics of the three sites are described, providing information about the complex instrumental suite and the produced data. The supersite adopts a policy of free sharing of its validated dataset with the community. Finally, the BAQUNIN potential is demonstrated with a case study involving a major fire that occurred in a waste treatment plant near the urban center of Rome, and the consequent investigation of the plume properties revealed by different instruments.

Demand and Interference Aware Adaptive Resource Management for High Throughput GEO Satellite Systems

The scarce spectrum and power resources, the inter-beam interference, together with the high traffic demand, pose new major challenges for the next generation of Very High Throughput Satellite (VHTS) systems. Accordingly, future satellites are expected to employ advanced resource/interference management techniques to achieve high system spectrum efficiency and low power consumption while ensuring user demand satisfaction. This paper proposes a novel demand and interference aware adaptive resource management for geostationary (GEO) VHTS systems. For this, we formulate a multi-objective optimization problem to minimize the total transmit power consumption and system bandwidth usage while matching the offered capacity with the demand per beam. In this context, we consider resource management for a system with full-precoding, i.e., all beams are precoded; without precoding, i.e., no precoding is applied to any beam; and with partial precoding, i.e., only some beams are precoded. The nature of the problem is non-convex and we solve it by jointly using the Dinkelbach and Successive Convex Approximation (SCA) methods. The simulation results show that the proposed method outperforms the benchmark schemes. Specifically, we show that the proposed method requires low resource consumption, low computational time, and simultaneously achieves a high demand satisfaction.

Location Management in Internet Protocol-Based Future LEO Satellite Networks: A Review

Future integrated terrestrial, aerial, and space networks will involve thousands of low-Earth-orbit (LEO) satellites, which will form a network of mega-constellations. These megaconstellations will play a significant role in providing communication and Internet services anywhere, at any time, and for everything. Due to the large scale and highly dynamic nature of future LEO satellite networks (SatNets), their management will be a complicated process, especially the aspect of mobility management and its two components: location management and handover management. In this article, we present a comprehensive and critical review of the state-of-the-art research in location management for LEO SatNets. First, we give an overview of the Internet Engineering Task Force (IETF) mobility management standards (e.g., Mobile IPv6 and Proxy Mobile IPv6) and discuss the limitations of their location management techniques for future LEO SatNets. We highlight the mobility characteristics of future LEO SatNets and their challenging features, and we describe two unprecedented future location management scenarios. A taxonomy of existing location management solutions for LEO SatNets is also presented with solutions classified according to three approaches. The &#x201C;Issues to consider&#x201D; section draws attention to critical points related to each of the reviewed approaches that should be considered in future LEO SatNets location management. To identify the research gaps, the current state of LEO SatNets location management is summarized. Noteworthy future research directions are recommended. The article provides a road map for researchers and industry to shape the future of location management for LEO SatNets.

Time Transfer From GPS for Designing a SmallSat-Based Lunar Navigation Satellite System

<h3>Abstract</h3> For the future lunar navigation satellite system (LNSS), a GPS-like constellation for the Moon, NASA has expressed interest in using a smallsat platform. However, many design decisions have yet to be finalized, including the orbit, constellation, and onboard clock. Furthermore, designing a dedicated smallsat-based LNSS limits the payload capacity, thus restricting the size, weight, and power (SWaP) of the onboard clock. We propose an LNSS design with time transfer from intermittently available GPS signals wherein we design a Kalman filter to estimate timing corrections for a low-SWaP clock. Additionally, we devise a lunar User Equivalent Range Error (UERE) metric to characterize the ranging accuracy of signals transmitted by an LNSS satellite. We further validate our time-transfer technique with simulations of an LNSS satellite in an elliptical lunar frozen orbit (ELFO) with an onboard chip scale atomic clock (CSAC) while analyzing the visibility effects of GPS, timing errors, and lunar UERE across ELFOs.