Stability of CubeSat Clocks and Their Impacts on GNSS Radio Occultation

doi:10.3390/rs14020362

	Stability of CubeSat Clocks and Their Impacts on GNSS Radio Occultation
	Allahvirdi-Zadeh, Amir 1; Awange, Joseph 1; El-Mowafy, Ahmed 1; Ding, Tong 1; Wang, Kan 2,3
	2022
发表期刊	REMOTE SENSING
卷号	14 期号:2 页码:26
摘要	Global Navigation Satellite Systems' radio occultation (GNSS-RO) provides the upper troposphere-lower stratosphere (UTLS) vertical atmospheric profiles that are complementing radiosonde and reanalysis data. Such data are employed in the numerical weather prediction (NWP) models used to forecast global weather as well as in climate change studies. Typically, GNSS-RO operates by remotely sensing the bending angles of an occulting GNSS signal measured by larger low Earth orbit (LEO) satellites. However, these satellites are faced with complexities in their design and costs. CubeSats, on the other hand, are emerging small and cheap satellites; the low prices of building them and the advancements in their components make them favorable for the GNSS-RO. In order to be compatible with GNSS-RO requirements, the clocks of the onboard receivers that are estimated through the precise orbit determination (POD) should have short-term stabilities. This is essential to correctly time tag the excess phase observations used in the derivation of the GNSS-RO UTLS atmospheric profiles. In this study, the stabilities of estimated clocks of a set of CubeSats launched for GNSS-RO in the Spire Global constellation are rigorously analysed and evaluated in comparison to the ultra-stable oscillators (USOs) onboard the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-2) satellites. Methods for improving their clock stabilities are proposed and tested. The results (i) show improvement of the estimated clocks at the level of several microseconds, which increases their short-term stabilities, (ii) indicate that the quality of the frequency oscillator plays a dominant role in CubeSats' clock instabilities, and (iii) show that CubeSats' derived UTLS (i.e., tropopause) atmospheric profiles are comparable to those of COSMIC-2 products and in situ radiosonde observations, which provided external validation products. Different comparisons confirm that CubeSats, even those with unstable onboard clocks, provide high-quality RO profiles, comparable to those of COSMIC-2. The proposed remedies in POD and the advancements of the COTS components, such as chip-scale atomic clocks and better onboard processing units, also present a brighter future for real-time applications that require precise orbits and stable clocks.
关键词	CubeSats precise orbit determination (POD) GNSS radio occultation (GNSS-RO) clock stability COSMIC-2 profiles
资助者	Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program ; Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program ; Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program ; Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program
DOI	10.3390/rs14020362
关键词[WOS]	ORBIT DETERMINATION ; CAPABILITIES
语种	英语
资助项目	Australian Research Council[DP 190102444] ; National Time Service Center, Chinese Academy of Sciences (CAS)[E167SC14] ; CAS "Light of West China" Program[XAB2018YDYL01]
资助者	Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program ; Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program ; Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program ; Australian Research Council ; Australian Research Council ; National Time Service Center, Chinese Academy of Sciences (CAS) ; National Time Service Center, Chinese Academy of Sciences (CAS) ; CAS "Light of West China" Program ; CAS "Light of West China" Program
WOS研究方向	Environmental Sciences & Ecology ; Geology ; Remote Sensing ; Imaging Science & Photographic Technology
WOS类目	Environmental Sciences ; Geosciences, Multidisciplinary ; Remote Sensing ; Imaging Science & Photographic Technology
WOS记录号	WOS:000747683700001
出版者	MDPI
引用统计
文献类型	期刊论文
条目标识符	http://210.72.145.45/handle/361003/13929
专题	高精度时间传递与精密测定轨研究室
通讯作者	Wang, Kan
作者单位	1.Curtin Univ, Sch Earth & Planetary Sci Spatial Sci, GPO Box U1987, Perth, WA 6845, Australia 2.Chinese Acad Sci, Natl Time Serv Ctr, Xian 710600, Peoples R China 3.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Allahvirdi-Zadeh, Amir,Awange, Joseph,El-Mowafy, Ahmed,et al. Stability of CubeSat Clocks and Their Impacts on GNSS Radio Occultation[J]. REMOTE SENSING,2022,14(2):26.
APA	Allahvirdi-Zadeh, Amir,Awange, Joseph,El-Mowafy, Ahmed,Ding, Tong,&Wang, Kan.(2022).Stability of CubeSat Clocks and Their Impacts on GNSS Radio Occultation.REMOTE SENSING,14(2),26.
MLA	Allahvirdi-Zadeh, Amir,et al."Stability of CubeSat Clocks and Their Impacts on GNSS Radio Occultation".REMOTE SENSING 14.2(2022):26.