Abstract. Seasonal transitions in Arctic sea ice, such as the melt onset, have been found to be useful metrics for evaluating sea ice in climate models against observations. However, comparisons of melt onset dates between climate models and satellite observations are indirect. Satellite data products of melt onset rely on observed brightness temperatures, while climate models do not currently simulate brightness temperatures, and must therefore define melt onset with other modeled variables. Here we adapt a passive microwave sea ice satellite simulator, the Arctic Ocean Observation Operator (ARC3O), to produce simulated brightness temperatures that can be used to diagnose the timing of the earliest snowmelt in climate models, as we show here using Community Earth System Model version 2 (CESM2) ocean-ice hindcasts. By producing simulated brightness temperatures and earliest snowmelt estimation dates using CESM2 and ARC3O, we facilitate new and previously impossible comparisons between the model and satellite observations by removing the uncertainty that arises due to definition differences. Direct comparisons between the model and satellite data allow us to identify an early bias across large areas of the Arctic at the beginning of the CESM2 ocean-ice hindcast melt season, as well as improve our understanding of the physical processes underlying seasonal changes in brightness temperatures. In particular, the ARC3O allows us to show that satellite algorithm-based melt onset dates likely occur after significant snowmelt has already taken place.
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Secret Key Distillation over Satellite-to-satellite Free-space Channel with Eavesdropper Dynamic Positioning
In this paper, the satellite-to-satellite secret-key-rate lower bounds are deter-mined for a realistic scenario where the eavesdropper has a limited size aperture. We also investigate eavesdropper’s optimal eavesdropping position with respect to Bob.
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- Award ID(s):
- 1907918
- NSF-PAR ID:
- 10249485
- Date Published:
- Journal Name:
- OSA Advanced Photonics Congress (AP) 2020 (IPR, NP, NOMA, Networks, PVLED, PSC, SPPCom, SOF)
- Page Range / eLocation ID:
- SpTu3I.4
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Quantum cryptography is the study of unconditional information security against an all-powerful eavesdropper in secret key distillation. However, the assumption of an omnipotent eavesdropper is too strict for some realistic implementations. In this paper, we study the realistic application model of secret key distillation over a satellite-to-satellite free-space channel in which we impose a reasonable restriction on the eavesdropper by setting an exclusion zone around the legitimate receiver as a defense strategy. We first study the case where the eavesdropper’s aperture size is unlimited so their power is only restricted by the exclusion zone. Then, we limit Eve’s aperture to a finite size and study the straightforward case when her aperture is in the same plane of Bob’s, investigating how an exclusion zone can help improve security. Correspondingly, we determine the secret key rate lower bounds as well as upper bounds. Furthermore, we also apply our results on specific discrete variable (DV) and continuous variable (CV) protocols for comparison. We show that, by putting reasonable restrictions on the eavesdropper through the realistic assumptions of an inaccessible exclusion zone, we can significantly increase the key rate in comparison to those without and do so with relatively lower transmission frequency. We conclude that this model is suitable for extended analysis in many light-gathering scenarios and for different carrier wavelengths.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1364/SPPCOM.2020.SpTu3I.4
