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作者： Rignot, E. University of California Irvine Dept. Earth System Science IrvineCA92697 United States Jet Propulsion Laboratory/Caltech PasadenaCA91109 United States University of California Irvine Dept. Civil and Environmental Engineering IrvineCA92697 United States

The ice sheets in Greenland and Antarctica, combined with glaciers and ice caps around the world, are contributing faster and sooner than expected to global sea level rise. Half a century of observations, physical models, and paleoclimate records suggest that sea level rise will exceed 1 meter this century, but more extreme rates of sea level rise can not be ruled out. I review the current state of knowledge on ice sheet and glacier mass balance, its driving physical mechanisms, their impacts on future sea level rise, and whether the most vulnerable sectors of Antarctica and Greenland have passed, or will soon pass, a point of no return. In several sectors of Greenland and Antarctica, I conclude that multi-meter sea level rise is inevitable, but the rate of sea level rise will depend on how urgently we keep climate warming under control and subsequently bring the climate system back toward pre-industrial levels. To reduce the uncertainties of projecting rapid rates of sea level rise in the coming century, significant research investments will be required, orders of magnitude lower than the cost of adapting to sea level rise, to obtain critical observations and develop more reliable atmosphere-ocean-ice coupled models. © 2022 Uspekhi Fizicheskikh Nauk. All rights reserved.

关键词： Climate change

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Autonomous Robotic Radio Source Localization via a Novel Gaussian Mixture Filtering Approach

arXiv

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arXiv 2025年

作者： Kim, Sukkeun Moon, Sangwoo Petrunin, Ivan Shin, Hyo-Sang Khattak, Shehryar Faculty of Engineering and Applied Sciences Cranfield University Cranfield United Kingdom Jet Propulsion Laboratory California Institute of Technology Pasadena United States Cho Chun Shik Graduate School of Mobility Korea Advanced Institute of Science and Technology Daejeon Korea Republic of

This study proposes a new Gaussian Mixture Filter (GMF) to improve the estimation performance for the autonomous robotic radio signal source search and localization problem in unknown environments. The proposed filter is first tested with a benchmark numerical problem to validate the performance with other state-of-practice approaches such as Particle Gaussian Mixture (PGM) filters and Particle Filter (PF). Then the proposed approach is tested and compared against PF and PGM filters in real-world robotic field experiments to validate its impact for real-world robotic applications. The considered real-world scenarios have partial observability with the range-only measurement and uncertainty with the measurement model. The results show that the proposed filter can handle this partial observability effectively whilst showing improved performance compared to PF, reducing the computation requirements while demonstrating improved robustness over compared techniques. Copyright © 2025, The Authors. All rights reserved.

关键词： Observability

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The Pitfalls of Ignoring Topography in Snow Retrievals: A Case Study with Emit

SSRN

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SSRN 2024年

作者： Bohn, Niklas Bair, Edward H. Brodrick, Philip G. Carmon, Nimrod Green, Robert O. Painter, Thomas H. Thompson, David R. Jet Propulsion Laboratory California Institute of Technology PasadenaCA United States Civil Group Leidos Inc. RestonVA United States Joint Institute for Regional Earth System Science and Engineering UCLA Los AngelesCA United States

Snow and ice surfaces are an important modulator of Earth’s climate as they reflect most of the incoming solar radiation favoring substantial cooling effects. Thereby, the amount of absorbed solar illumination regulates radiative forcing, which in turn steers melting processes on ice sheets and glaciers. Global patterns of snow darkening, induced by the accumulation of small light-absorbing particles (LAPs), such as dust or algae, lead to an intensified radiative forcing and melting of Earth’s snow cover. It is one of the driving factors for both global sea level rise and increasing air temperature. Mapping and quantifying LAPs on both temporal and spatial scales is therefore needed to improve the prediction of melt rates and their impacts on climate change. High-resolution visible-to-shortwave-infrared (VSWIR) imaging spectrometers herald a new era of passive spaceborne remote sensing, which will help to fulfill this objective. This technology provides continuous spectral channels throughout the solar spectrum, allowing to detect narrow LAP absorption bands. One of these instruments is NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) that was launched to the International Space Station (ISS) in July 2022. The prime mission focus is to deliver maps of surface minerals from arid dust source regions in order to inform Earth system models (ESM) of atmospheric transport and radiative forcing. In addition, the EMIT target mask also includes snow cover in low to mid-latitude mountainous regions, such as the Western US, the Andes in South America, or high-mountain Asia, all of which are prone to surface deposition of small dust particles after traveling hundreds to thousands of kilometers through the atmosphere. Accurate retrievals of snow surface properties in those regions require precise accounting for anisotropy and topography due to varying forward scattering intensity as a function of illumination and observation geometry. In this contribution, we invert

关键词： Radiative transfer

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Nonreciprocal Dissipation engineering via Strong Coupling with a Continuum of Modes

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Physical Review X 2024年第2期14卷 021002-021002页

作者： Yishu Zhou Freek Ruesink Shai Gertler Haotian Cheng Margaret Pavlovich Eric Kittlaus Andrew L. Starbuck Andrew J. Leenheer Andrew T. Pomerene Douglas C. Trotter Christina Dallo Katherine M. Musick Eduardo Garcia Robert Reyna Andrew L. Holterhoff Michael Gehl Ashok Kodigala John Bowers Matt Eichenfield Nils T. Otterstrom Anthony L. Lentine Peter Rakich Department of Applied Physics Yale University New Haven Connecticut USA Jet Propulsion Laboratory California Institute of Technology Pasadena California USA Microsystems Engineering Science and Applications Sandia National Laboratories Albuquerque New Mexico USA Department of Electrical and Computer Engineering University of California Santa Barbara California USA James C. Wyant College of Optical Sciences University of Arizona Tucson Arizona USA

Optical nonreciprocity plays a key role in almost every optical system, directing light flow and protecting optical components from backscattered light. Controllable forms of on-chip nonreciprocity are needed for the robust operation of increasingly sophisticated photonic integrated circuits (PICs) in the context of classical and quantum computation, networking, communications, and sensing. However, it has been challenging to achieve wideband, low-loss optical nonreciprocity on-chip. In this paper, we demonstrate strong coupling and Rabi-like energy exchange between photonic bands, possessing a continuum of modes, to unlock nonreciprocity and frequency translation over wide optical bandwidths in silicon. Using a traveling-wave phonon field to drive indirect interband photonic transitions, we demonstrate band hybridization that enables an intriguing form of nonreciprocal dissipation engineering. Using the converted mode to create a nonreciprocal dissipation channel, we demonstrate a frequency-neutral, low-loss (less than 1 dB) isolator with high nonreciprocal contrast (more than 14 dB) and broad operating bandwidth (more than 59 GHz). Additionally, through the implementation of complete interband conversion, we demonstrate a high extinction (more than 55 dB) optical frequency translation operation with near-unity efficiency.

关键词： Integrated optics Optomechanics Phonons Optical isolators Rabi model

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Nonharmonic contributions to the high-temperature phonon thermodynamics of Cr

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Physical Review B 2023年第5期107卷 054312-054312页

作者： C. M. Bernal-Choban H. L. Smith C. N. Saunders D. S. Kim L. Mauger D. L. Abernathy B. Fultz Applied Physics and Materials Science California Institute of Technology Pasadena California 91125 USA Physics and Astronomy Swarthmore College Swarthmore Pennsylvania 19081 USA Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Jet Propulsion Laboratory Pasadena California 91109 USA Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA

Phonon densities of states (DOSs) of body-centered cubic chromium were measured by time-of-flight inelastic neutron scattering at temperatures up to 1493 K. Density functional theory calculations with both quasiharmonic (QH) and anharmonic (AH) methods were performed at temperatures above the Néel temperature. Features in the phonon DOSs decrease in energy (soften) substantially with temperature. A Born–von Kármán analysis using fits to the experimental DOSs reveals a softening of almost 17% of the high-transverse phonon branch between 330 and 1493 K. The low-transverse branch changes by approximately half this amount. The AH calculations capture the observed behavior of the two transverse phonon branches, but the QH calculations give some inverted trends. Vibrational entropies from phonons and electrons are obtained, and their sum is in excellent agreement with the entropy of chromium obtained by calorimetry, indicating that above 330 K, no explicit temperature-dependent magnetic contributions are necessary.

关键词： Anharmonic lattice dynamics Entropy Phonons Spin fluctuations Ab initio calculations Neutron scattering

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Estimating Dust on Snow - Application of a Coupled Atmosphere-Surface Model to Spaceborne Emit Imaging Spectrometer Data

Estimating Dust on Snow - Application of a Coupled Atmospher...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： N. Bohn E. H. Bair P. G. Brodrick N. Carmon R. O. Green T. H. Painter D. R. Thompson Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA Earth Research Institute University of California Santa Barbara CA USA Joint Institute for Regional Earth System Science and Engineering University of California Los Angeles CA USA

Radiative forcing by small dust particles deposited on snow plays a key role in climate change. Detection and quantification of these particles is essential for predicting melt rates, and assessing the associated impacts on Earth’s climate. NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) aims to improve our understanding of the Earth’s dust source and sink regions. The latter include snow surfaces in topographically challenging mountainous terrain. We present estimated snow reflectance, dust concentration, and radiative forcing from a new retrieval framework, and highlight their sensitivity to topographic characteristics. These findings will be essential for updating snow melt and climate models, but also for the conception of retrieval algorithms for upcoming global spaceborne imaging spectroscopy missions, including NASA’s Surface Biology and Geology (SBG).

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The Pitfalls of Ignoring Topography in Snow Retrievals: A Case Study with Emit

SSRN

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SSRN 2023年

Snow surfaces play a key role in climate change, as increased melting over the past decades significantly contributes to global sea level rise. Melting dynamics are controlled by the amount of solar radiation absorbed by the surface. Radiative forcing increases when snow is darkened by the accumulation of small light-absorbing particles (LAPs) such as dust or algae. Consequently, quantifying these particles is essential for predicting melt rates on ice sheets and mountainous glaciers, and for assessing the associated impacts on climate change. A new generation of orbital VSWIR imaging spectrometers provides the measurements needed to achieve this objective by featuring narrow, continuous spectral channels that are able to resolve subtle LAP absorption features. In particular, NASA’s Earth Surface Mineral Dust Source Investigation (EMIT), launched in July 2022 and installed on the International Space Station (ISS), aims to improve our understanding of the Earth’s mineral dust sources and their climate impacts. These impacts include dust deposition on snow surfaces in mountainous regions, such as the Western US and the Andes in South America. Recent work has demonstrated that a simultaneous inversion of atmosphere and surface state using optimal estimation (OE) shows promising potential to quantify snow biogeophysical properties from space. However, accurate retrievals require precise accounting for surface reflectance anisotropy and observation/illumination geometry. In this contribution, we present a modification of the algorithm by using a discrete anisotropic surface-atmosphere radiative transfer model that couples the MODTRAN code with a combination of Mie scattering calculations and the multistream DISORT program. The model provides a physics-based parameterization of the surface, including illumination and observation angles, whose consideration is particularly important for strongly forward scattering snow surfaces. The new implementation leads to a well posed

关键词： Topography

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Neural-Rendezvous: Provably Robust Guidance and Control to Encounter Interstellar Objects

arXiv

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arXiv 2022年

作者： Tsukamoto, Hiroyasu Chung, Soon-Jo Nakka, Yashwanth Kumar Donitz, Benjamin Mages, Declan Ingham, Michel Division of Engineering and Applied Science California Institute of Technology PasadenaCA91125 United States Jet Propulsion Laboratory California Institute Technology PasadenaCA91109 United States

Interstellar objects (ISOs) are likely representatives of primitive materials invaluable in understanding exoplanetary star systems. Due to their poorly constrained orbits with generally high inclinations and relative velocities, however, exploring ISOs with conventional human-in-the-loop approaches is significantly challenging. This paper presents Neural-Rendezvous – a deep learning-based guidance and control framework for encountering fast-moving objects, including ISOs, robustly, accurately, and autonomously in real time. It uses pointwise minimum norm tracking control on top of a guidance policy modeled by a spectrally-normalized deep neural network, where its hyperparameters are tuned with a loss function directly penalizing the MPC state trajectory tracking error. We show that Neural-Rendezvous provides a high probability exponential bound on the expected spacecraft delivery error, the proof of which leverages stochastic incremental stability analysis. In particular, it is used to construct a non-negative function with a supermartingale property, explicitly accounting for the ISO state uncertainty and the local nature of nonlinear state estimation guarantees. In numerical simulations, Neural-Rendezvous is demonstrated to satisfy the expected error bound for 100 ISO candidates. This performance is also empirically validated using our spacecraft simulator and in high-conflict and distributed UAV swarm reconfiguration with up to 20 UAVs. Copyright © 2022, The Authors. All rights reserved.

关键词： Stochastic systems

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Learning spatial response functions from large multi-sensor AIRS and MODIS datasets 26

Learning spatial response functions from large multi-sensor ...

引用

Earth Observing systems XXVI 2021

作者： Yanovsky, Igor Pagano, Thomas S. Manning, Evan M. Broberg, Steven E. Aumann, Hartmut H. Vese, Luminita A. Jet Propulsion Laboratory California Institute of Technology PasadenaCA United States Joint Institute for Regional Earth System Science and Engineering University of California Los AngelesCA United States Department of Mathematics University of California Los AngelesCA United States

ISBN: (数字)9781510644977

ISBN: (纸本)9781510644960

We use large datasets from the Atmospheric Infrared Sounder (AIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) to derive AIRS spatial response functions and study their potential variations over the mission. The new reconstructed spatial response functions can be used to reduce errors in the radiances in non-uniform scenes and improve products generated using both AIRS and MODIS data. AIRS spatial response functions are distinct for each of its 2378 channels and each of its 90 scan angles. We develop the mathematical model and the optimization framework for deriving spatial response functions for two AIRS channels with low water vapor absorption and various scan angles. We quantify uncertainties in the derived reconstructions and study how they differ from pre-flight spatial response functions. We show that our approach generates reconstructions that agree with the data more accurately compared to pre-flight spatial responses. We derive spatial response functions using data collected during successive dates in order to ascertain the repeatability of the reconstructed spatial response functions. We also compare the derived spatial response functions based on data collected in the beginning, the middle, and at the current state of the mission in order to study changes in reconstructions over time. © 2021 SPIE.

关键词： Inverse problems

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CYGNSS Ocean Surface Heat Flux Product Development, Updates, and Applications with Extratropical Cyclones and Atmospheric Rivers

CYGNSS Ocean Surface Heat Flux Product Development, Updates,...

引用

IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Juan A. Crespo Shakeel Asharaf Derek J. Posselt Catherine M. Naud Alison Cobb Joint Institute for Regional Earth System Science and Engineering University of California Los Angeles Jet Propulsion Laboratory California Institute of Technology Columbia University and NASA Goddard Institute for Space Studies Center for Western Weather and Water Extremes Scripps Institution of Oceanography University of California San Diego

Latent and sensible ocean surface heat fluxes (LHF and SHF, respectively) can significantly impact the genesis and evolution of climate and weather systems. As heat fluxes increase within the boundary layer, static stability decreases, leading to a lower lifted condensation level, which could lead to dry and moist convection development in various weather systems [1] - [2] . The energy transported through LHF and SHF between the ocean surface and boundary layer can influence weather systems at the microscale, mesoscale, and synoptic scale, including, but not limited to, tropical and extratropical cyclones, convection, and large-scale waves such as the Madden-Julian Oscillation [3] - [6] .

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