Advances in Space Research最新文献

{"title":"Impact of offsets on GNSS time series stochastic noise properties and velocity estimation","authors":"Jiahui Huang ,&nbsp;Xiaoxing He ,&nbsp;Shunqiang Hu ,&nbsp;Feng Ming","doi":"10.1016/j.asr.2024.12.016","DOIUrl":"10.1016/j.asr.2024.12.016","url":null,"abstract":"<div><div>This study systematically investigates the efficiency of RMLE and MLE algorithms for noise model identification using various information criteria and examines the influence of offsets on noise properties and velocity estimation. Through experimental analysis on simulated GNSS time series, we confirm that RMLE and MLE accurately discriminate among four different noise models using AIC, BIC, and BIC_tp information criteria. For time series longer than 15 years, RMLE is recommended as the default method, while MLE outperforms RMLE for short time series when the underlying noise model is FN, PL, or GGM. RMLE proves more sensitive to the RW component than the MLE algorithm, particularly with shorter time series (less than 10 years). We also confirm that the addition of offsets does not transform non-GGM optimal noise models into GGM noise models, further supporting that GGM noise models in GNSS time series are not an artifact and that residual offsets are not the underlying cause of GNSS position time series exhibiting GGMWN characteristics. For selected real GNSS time series without offsets from Extended Solid Earth Science ESDR System, we further confirm that PLWN and FNWN remain the primary noise processes best describing GNSS time series. A noteworthy discovery is the observation of more RW components (approximately 19.22 %) than in previous research with 15-year long-term GNSS time series using the RMLE algorithm. Additionally, we still find GGM as the optimal noise model in the vertical component, ensuring it is real and not an artifact. Furthermore, even with artificially induced frequent offsets, we observe that only about 0.35 % of sites’ optimal noise models change from non-GGMWN models to GGMWN, consistent with the simulated GNSS time series experiments.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3397-3413"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First observational investigation on the temporal trends of Vertical Total Electron Content (VTEC) over an equatorial station: Discerning the impacts of Mora and Ockhi – Two tropical cyclones in 2017","authors":"Swati Chowdhury,&nbsp;D. Bala Subrahamanyam,&nbsp;R.K. Choudhary","doi":"10.1016/j.asr.2024.11.078","DOIUrl":"10.1016/j.asr.2024.11.078","url":null,"abstract":"<div><div>This study examines the impact of two tropical cyclones (Mora and Ockhi, 2017) over the Northern Indian Ocean on vertical total electron content (VTEC) over Trivandrum, by comparing data from similar periods in 2018 and 2019. To ensure accuracy, a precise data-screening method was implemented to exclude the potential effects of geomagnetic storms and other tropical cyclones on VTEC. Results showed a significant depletion in VTEC, ranging from 7% to 19%, which varied based on the intensity of the cyclones and their distance from the measurement site. The period analyzed coincided with the declining phase of the 24th solar cycle, during which VTEC naturally decreased from 2017 to 2019. The present analysis reports a sharp depletion in the VTEC during the passage of the cyclone, the first of its kind, emphasizing the TC-influence on the upper atmosphere, which was seen to extend even after the landfall.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3651-3660"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An image simulator of lunar far-side impact flashes captured from the Earth-Moon L2 point","authors":"Da Song ,&nbsp;Hong-bo Cai ,&nbsp;Shen Wang ,&nbsp;Jing Wang","doi":"10.1016/j.asr.2024.12.002","DOIUrl":"10.1016/j.asr.2024.12.002","url":null,"abstract":"<div><div>Impact flashes on the moon are caused by high-speed collisions of celestial bodies with the lunar surface. The study of the impacts is critical for exploring the evolutionary history and formation of the Moon, and for quantifying the risk posed by the impacts to future human activity. Although the impacts have been monitored from the Earth by a few projects in past 20 years, the events occurring on the lunar far side have not been explored systematically so far. We here present an end-to-end image simulator dedicated to detecting and monitoring the impacts from space, which is useful for future mission design. The simulator is designed for modularity and developed in the Python environment, which is mainly composed of four components: the flash temporal radiation, the background emission, the telescope and the detector used to collect and measure the radiation. Briefly speaking, with a set of input parameters, the simulator calculates the flash radiation in the context of the spherical droplet model and the background emission from the lunar surface. The resulting images are then generated by the simulator after considering a series observational effects, including the stray light, transmission of the instrument, point spread function and multiple kinds of noise caused by a CCD/CMOS detector. The simulator is validated by comparing the calculation with the observations taken on the ground. The modular design enables the simulator to be improved and enhanced by including more complex physical models in the future, and to be flexible for other future space missions.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 4061-4079"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interseismic strain accumulation of the 2022 Ms 6.8 Luding earthquake (Tibet) and discussion of the seismogenic mechanism","authors":"Layue Li ,&nbsp;Wei Zhan ,&nbsp;Changyun Chen ,&nbsp;Yujiao Niu","doi":"10.1016/j.asr.2024.12.019","DOIUrl":"10.1016/j.asr.2024.12.019","url":null,"abstract":"<div><div>On September 5, 2022, a <em>M</em>s 6.8 earthquake struck the Xianshuihe fault zone, a large-scale left-lateral strike-slip fault zone on the southeastern margin of the Tibetan Plateau, filling the Moxi seismic gap and resulting in significant economic losses and casualties. To clarify the seismogenic process and mechanism of this earthquake, we conducted a comprehensive and in-depth analysis on the stress–strain accumulation characteristics preceding the <em>M</em>s 6.8 Luding earthquake based on the Global Positioning System (GPS) data and focal mechanism solutions. Our results reveal that the epicenter area of the Luding earthquake underwent long-term NWW-SEE directed compression and NEE-SWW directed tension, and gradually accumulates strain energy predominantly through shear deformation, with a sinistral shear strain rate of 3.4 × 10⁻⁸/a, which is associated with regional tectonic movement. Additionally, the focal area of the Luding earthquake exhibited a high accumulation of strain energy prior to the rupture, with a maximum locking depth of approximately 15.6 km. The Moxi section, where the Luding earthquake occurred, is likely approaching the late stage of its seismogenic cycle. The tectonic stress analysis further confirms that the mainshock of the Luding earthquake was primarily triggered by tectonic shear stress. These findings suggest that the <em>M</em>s 6.8 Luding earthquake was a normal release of strain energy accumulated on a NW-striking strike-slip fault, mainly driven by the regional tectonic stress field resulting from the India-Eurasia plate convergence and the resistance from the rigid Sichuan Basin.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3414-3426"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance assessment of multiple ambiguity resolution methods in single LEO precision orbit determination","authors":"Mengmeng Li ,&nbsp;Xingyu Zhou ,&nbsp;Qianxin Wang ,&nbsp;Kai Li ,&nbsp;Ming Gao ,&nbsp;Tong Cheng ,&nbsp;Han Zhang","doi":"10.1016/j.asr.2024.11.074","DOIUrl":"10.1016/j.asr.2024.11.074","url":null,"abstract":"<div><div>Low Earth Orbit (LEO) satellites play a vital role in fields of gravity field recovery, meteorological detection, and Precise Point Positioning (PPP) of augmented Global Navigation Satellite Systems (GNSS), which makes the precise orbit determination (POD) of LEO satellites the key to their mission-execution. Ambiguity resolution (AR) is an effective method to improve the orbit accuracy of LEO satellites, among which the Single Difference (SD) AR method requires GNSS hardware bias products. Besides, Track-to-Track (T2T) AR and Single Difference Track-to-Track (SDT2T) AR can be used as the alternative methods in the scenarios without any GNSS bias products. In this study, the reduced dynamic POD (RDPOD) of the GRACE-FO and SWARM constellations from day 001 to 150 of 2020 was performed using the SD AR, T2T AR and SDT2T AR methods. The results showed that the performance of T2T AR is inferior to that of SDT2T AR and SD AR due to the gradual variability in the phase fractional bias of satellites and receivers. By analyzing the relationship between the success rate of T2T AR and the time interval between adjacent ambiguities, it is found that the success rate of T2T AR is higher when the time interval is within 30 min. Therefore, it can be assumed that the fractional cycle biases of the receivers remains constant within 30 min because the performance of T2T AR highly depends on the stability of the fractional cycle biases of the receivers. With impacts caused by the receiver fractional biases eliminated, SDT2T AR significantly outperforms T2T AR and achieves comparable performance with SD AR. Therefore, in the cases that GNSS bias products are unavailable, SDT2T AR is recommended as the preferred option for single LEO POD.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3870-3890"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An approximate model for the computation of in-orbit collision probabilities using importance sampling","authors":"Yannick Sztamfater-Garcia,&nbsp;Manuel Sanjurjo-Rivo,&nbsp;Guillermo Escribano,&nbsp;Harold Molina-Bulla,&nbsp;Joaquin Miguez","doi":"10.1016/j.asr.2024.12.074","DOIUrl":"10.1016/j.asr.2024.12.074","url":null,"abstract":"<div><div>The risk of orbital collisions is at an all-time high. Standard methods which compute the probability of collision (PoC) often make restrictive assumptions which produce numerically efficient solutions, the quality of which may decrease over long time-spans. The crude Monte Carlo (CMC) simulation makes few assumptions and can produce high quality estimates; however, its computational cost can be prohibitively high. We introduce a new method based on importance sampling (IS), which aims to attain the accuracy of a CMC simulation at a fraction of the computational cost. To accomplish this, we propose a surrogate dynamical model which exploits Keplerian conjunction geometry and applies a linear correction to approximate the full-dynamics of the conjunction scenario, reducing the computational load of evaluating the dynamical model. This linear approximation is satisfactorily validated by means of high-fidelity model evaluations. The PoC results, when the method is applied on LEO and GEO scenarios, show agreement with an independent CMC benchmark simulation for the calculation of the PoC at a fraction of the computational cost.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3791-3805"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing spatial pattern of urban green space coverage and its determining factors: A case study in the Yangtze River Delta region in China","authors":"Xiaodan Liu ,&nbsp;Yan Li ,&nbsp;Henghui Xi ,&nbsp;Xiaohong Li ,&nbsp;Yiyang Wu ,&nbsp;Shirui Yuan ,&nbsp;Muwu Xu ,&nbsp;Weixin Ou ,&nbsp;Conghong Huang","doi":"10.1016/j.asr.2024.12.009","DOIUrl":"10.1016/j.asr.2024.12.009","url":null,"abstract":"<div><div>Information on green space coverage patterns and influencing factors in built-up areas is essential for urban planners, as it is related to the well-being of residents. In this study, WorldCover land cover product was used to extract green space maps and analyze landscape patterns of urban green space coverage (UGSC) of built-up areas in China’s Yangtze River Delta region under different scales (i.e., built-up area, district/county, and prefecture-level city) in 2020. Additionally, cold and hot spot analyses were performed to represent the regional aggregation of high and low green space coverage. The random forest model was used to calculate the relative importance and marginal effect of the factors influencing UGSC. The results show that, in general, the UGSC gradually decreases from the southern to the northern regions. The pattern of UGSC is basically the same as that of tree/shrub coverage. Precipitation, the size of built-up area, and the area of urban paved roads are the main influencing factors of UGSC. Nonlinear relationships are observed between the size of built-up areas and UGSC, as well as between the area of urban paved roads and UGSC. The detailed mapping of the UGSC pattern and identifying key influencing factors offer valuable insights for urban planning and sustainable development.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3362-3374"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Successes, misses and false alarms in predicting global/seasonal equatorial plasma bubble occurrences with the ROCSAT data","authors":"S.-Y. Su ,&nbsp;H.-H. Ho ,&nbsp;C.-K. Chao ,&nbsp;C.H. Liu","doi":"10.1016/j.asr.2024.12.067","DOIUrl":"10.1016/j.asr.2024.12.067","url":null,"abstract":"<div><div>The density variations at a constant height such as observed by the circularly orbiting ROCSAT-1 spacecraft are studied to construct a “prediction model” for the occurrences, no-occurrences, misses and false alarms of global/seasonal equatorial plasma bubble (EPB) occurrences. This global/seasonal prediction model is different from previous studies that merely provide the seasonal EPB occurrence probability at a local time region or globally. The current model uses the density increment above the seasonal mean to predict the EPB occurrences by constructing a contingency table that counts the numbers of successes, fails, misses, and false alarms in predicting the EPB occurrences. Different thresholds of density increment are used for the criteria in prediction to obtain an optimal result in the prediction model. The success of the model for predicting the global EPB occurrences or no-occurrences varies between 75% and 85% for any season between 1999 and 2004 during the moderate to high solar activity period. Studies of the causes for the misses and false alarms in the existing prediction result lead us to propose that additional observational parameter besides the density increment in the prediction model should be included. This additional parameter should be the seeding agent for the RTI process that related to the atmospheric/ionospheric background conditions in the lower ionosphere.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3589-3600"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the correlation between hemispheric solar activity and geomagnetic indices: A study utilizing wavelet analysis technique","authors":"A.M. El-Taher ,&nbsp;B.M. Habashy ,&nbsp;M.A. El-Borie ,&nbsp;A.A. Bishara ,&nbsp;S.F. Ibrahim","doi":"10.1016/j.asr.2025.02.022","DOIUrl":"10.1016/j.asr.2025.02.022","url":null,"abstract":"<div><div>The impact of the sunspot areas (<strong><em>SSAs</em></strong>), which indicate an asymmetrical distribution of solar activity, on the geomagnetic disturbances (<strong><em>aa, Ap, Kp, and Dst</em></strong>) between 1986 and 2021 is the main topic of the present work. Based on the distribution of monthly average of the hemispheric <strong><em>SSAs</em></strong>, the monthly averages of geomagnetic indices have been divided into northern and southern groups. By using the continuous wavelet power spectrum (<strong>WPS</strong>) technique, the short-, mid- and long-term fluctuations, as well as the asymmetry in the periodicities of geomagnetic parameters across northern and southern groups have been assessed. Periodic variations in the sunspot activity predominance in each solar hemisphere across the various phases of the solar activity cycles under consideration, have been found. The southern hemisphere of the Sun has more solar activity than the northern one. Furthermore, the correlation magnitudes for <strong>SSAs</strong>, <strong><em>Dst, Ap, aa,</em></strong> <em>and</em> <strong><em>Kp</em></strong> are, respectively, 0.87, 0.55, 0.5, 0.24, and 0.06. Our study revealed several mid-term periodicities, such as a quasi-biennial periodicity (QBO) of two to three years, a quasi-triennial periodicity (QTO) of three to four years, a semiannual periodicity of around half a year, and an annual periodicity of about one year. Conversely, our study indicated that the southern groups of <strong><em>aa, ap, Kp</em></strong>, and <strong><em>Dst</em></strong> had a periodicity of 0.8-yr. In the southern groups of <strong><em>Ap, aa, Kp</em></strong>, and <strong><em>Dst</em></strong>, our results showed a 1.7-year periodicity that was below the 95% confidence level. The southern groups of <strong><em>Dst</em></strong> and <strong><em>SSAs</em></strong> had a 3.5-year periodicity. The main cause of many of the periodicities remains unknown, despite the fact that a wide range of periodicities, from short- to long-term, have been found in many solar and geomagnetic parameters.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 8","pages":"Pages 6522-6542"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infrared properties of Planetary Nebulae with PG1159 central stars","authors":"C. Muthumariappan ,&nbsp;K. Khushbu ,&nbsp;V. Kerni","doi":"10.1016/j.asr.2024.12.032","DOIUrl":"10.1016/j.asr.2024.12.032","url":null,"abstract":"<div><div>We study the properties of 26 PNe with PG1159-type central stars known till date and compare them with the properties of PNe having [WR], <em>wels</em> and hydrogen-rich central stars published earlier. We use archival photometric measurements of <span><math><mrow><mn>2</mn><mi>MASS</mi></mrow></math></span> for near-IR analysis and <em>WISE</em> and <em>IRAS</em> data for mid- and far-IR analysis and derive the IR properties of PG1159-PNe. We analyze the IR colour-colour diagrams of PG1159-PNe and compare them with the other three groups of PNe. Similar to the [WR]-PNe, many PG1159-PNe also show large amount of near-IR emission from the hot-dust component but their AGB dust is relatively cooler. We also report here the dust colour temperatures, dust masses, dust-to-gas mass ratios, IR luminosities and IR excess of PG1159-PNe and plot them against their surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness (age) and compare them with the distribution of other groups of PNe. The IR luminosity and dust temperature show strong correlation with surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness, however, the dust-to-gas mass ratio and IR excess do not show any trend. While the mean dust mass has a lower value for PG1159-PNe, in compared to other groups, the average dust-to-gas mass ratio is found to be marginally larger for PG1159-PNe. An analysis of the number distribution of different groups of PNe against surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness shows that a) younger [WR]-, <em>wels</em>- and normal-PNe have a similar distribution indicating that they all have evolved from the AGB in a similar way, b) while there is an overlap of surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness between [WR]- and PG1159-PNe, showing an evolutionary connection between them, there exists a significant gap between the values derived for <em>wels</em>- and PG1159-PNe.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 4126-4140"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}