POSSIBILITY OF HIGH-FREQUENCY OBSERVATION OF INUNDATION AREA BY SMALL SAR SATELLITES CONSTELLATION

Author(s):  
Natsumi KITAJIMA ◽  
Rie SETO ◽  
Dai YAMAZAKI ◽  
Xudong ZHOU ◽  
Wenchao MA ◽  
...  
2021 ◽  
Author(s):  
Xuebo Li ◽  
Yongxiang Huang ◽  
Guohua Wang ◽  
Xiaojing Zheng

Abstract. Partially due to the global climate change, the sand and dust storms (SDS) occurred more and more frequently, yet a detailed measurement of the SDS event at different heights is still lacking. Here we provide a high frequency observation in the Qingtu Lake Observation Array (QLOA), China. The wind and dust information were measured simultaneously at different wall-normal heights during the SDS process. The datasets span the period from 17 March to 9 June 2016. The wind speed and direction are recorded by a sonic anemometer with a sampling frequency 50 Hz, while the particulate matter 10 (PM10) is sampled simultaneously by a dust monitor with a sampling frequency 1 Hz. The wall-normal array had 11 sonics and monitors spaced logarithmically from z = 0.9 to 30 m, where the spacing is about 2-meter between the sonic anemometer and dust monitor at the same height. Based on its non-stationary feature, the SDS event can be divided into three stages, i.e., ascending, stabilizing and descending stages, in which the dynamic mechanism of the wind and dust fields might be different. This is preliminarily characterized via the classical Fourier power analysis. Temporal evolution of the scaling exponent from Fourier power analysis suggests slightly below the classical Kolmogorov value of −5/3 for the three-dimensional homogeneous and isotropic turbulence. During the stabilizing stage, the collected PM10 shows a very intermittent pattern, which can be further linked with the burst events in the turbulent atmospheric boundary layer. This dataset is valuable for a better understanding the SDS dynamics, which has being publicly available at Zenodo through the DOI 10.5281/zenodo.5034196 (Li et al., 2021a).


2019 ◽  
Vol 227 ◽  
pp. 151-161 ◽  
Author(s):  
Xinrong Chen ◽  
Shaoling Shang ◽  
Zhongping Lee ◽  
Lin Qi ◽  
Jing Yan ◽  
...  

2021 ◽  
Vol 13 (12) ◽  
pp. 5819-5830
Author(s):  
Xuebo Li ◽  
Yongxiang Huang ◽  
Guohua Wang ◽  
Xiaojing Zheng

Abstract. Partially due to global climate change, sand and dust storms (SDSs) have occurred more and more frequently, yet a detailed measurement of SDS events at different heights is still lacking. Here we provide a high-frequency observation from the Qingtu Lake Observation Array (QLOA), China. The wind and dust information were measured simultaneously at different wall-normal heights during the SDS process. The datasets span the period from 17 March to 9 June 2016. The wind speed and direction are recorded by a sonic anemometer with a sampling frequency of 50 Hz, while particulate matter with a diameter of 10 µm or less (PM10) is sampled simultaneously by a dust monitor with a sampling frequency of 1 Hz. The wall-normal array had 11 sonic anemometers and monitors spaced logarithmically from z=0.9 to 30 m, where the spacing is about 2 m between the sonic anemometer and dust monitor at the same height. Based on its nonstationary feature, an SDS event can be divided into three stages, i.e., ascending, stabilizing and descending stages, in which the dynamic mechanism of the wind and dust fields might be different. This is preliminarily characterized by the classical Fourier power analysis. Temporal evolution of the scaling exponent from Fourier power analysis suggests a value slightly below the classical Kolmogorov value of -5/3 for the three-dimensional homogeneous and isotropic turbulence. During the stabilizing stage, the collected PM10 shows a very intermittent pattern, which can be further linked with the burst events in the turbulent atmospheric boundary layer. This dataset is valuable for a better understanding of SDS dynamics and is publicly available in a Zenodo repository at https://doi.org/10.5281/zenodo.5034196 (Li et al., 2021a).


2020 ◽  
Vol 24 ◽  
pp. 827-841
Author(s):  
Alexandre Brouste ◽  
Marius Soltane ◽  
Irene Votsi

The present paper concerns the parametric estimation for the fractional Gaussian noise in a high-frequency observation scheme. The sequence of Le Cam’s one-step maximum likelihood estimators (OSMLE) is studied. This sequence is defined by an initial sequence of quadratic generalized variations-based estimators (QGV) and a single Fisher scoring step. The sequence of OSMLE is proved to be asymptotically efficient as the sequence of maximum likelihood estimators but is much less computationally demanding. It is also advantageous with respect to the QGV which is not variance efficient. Performances of the estimators on finite size observation samples are illustrated by means of Monte-Carlo simulations.


Author(s):  
W. E. Lee ◽  
A. H. Heuer

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.


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