scholarly journals Large area monitoring with a MODIS-based Disturbance Index (DI) sensitive to annual and seasonal variations

2009 ◽  
Vol 113 (6) ◽  
pp. 1250-1261 ◽  
Author(s):  
Nicholas C. Coops ◽  
Michael A. Wulder ◽  
Donald Iwanicka
2021 ◽  
Author(s):  
Anna Yasyukevich ◽  
Vera Sivtseva ◽  
Irina Medvedeva ◽  
Marina Chernigovskaya ◽  
Petr Ammosov ◽  
...  

<p>Based on the data of Total Electron Content (TEC) and OH rotational temperature, we analyze temporal and spatial features of the level of short-term variability (within the periods of up to several hours) at the ionosphere and the upper mesosphere. The study is carried out at three points located at mid-latitude, subauroral, and high-latitude regions during for more than 5 years period. The dynamics of variability, both in the ionosphere and at the mesopause, have the similar pattern with a clear seasonal variation. The maximum in the variability is registered in winter, and it exceeds up to 5-6 times the variability level during the summer period. This feature is observed regularly. The revealed dynamics does not correlate with changes the in geomagnetic and solar activities. The variability within considered periods is generally related to activity of Internal Gravity Waves in the upper atmosphere. We suggest that a source of the related seasonal variations in the variability may be the stratospheric high-velocity jet stream that develops in the subauroral regions during winter months. We propose a stratosphere disturbance index based on Era-5 Reanalysis data. The index is shown to have a maximum at subpolar regions and experience the similar regular seasonal variation with a maximum during winter months. We show a clear correlation between the mesosphere/ionosphere variability indices and the stratosphere disturbance index. The obtained results indicate a strong coupling between the short-period variability in the ionosphere, in the upper mesosphere, and in the subauroral stratosphere. The study is supported by the Russian Science Foundation Grant No. 20-77-00070.</p>


Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4364
Author(s):  
Pengju Xu ◽  
Wentao Wang

Although cable-based seismic sensing systems have provided reliable data in the past several decades, they become a bottleneck for large-area monitoring and critical environmental (volcanic eruptions) sensing because of their cost, difficulty in deploying and expanding, and lack of accurate three-dimensional geographic information. In this paper, a new wireless sensing system is designed consisting of a portable satellite device, a self-sustaining power source, a low-cost computational core, and a high-precision sensor. The emphasis of this paper is to implement in low-cost hardware without requirements of highly specialized and expensive data acquisition instruments. Meanwhile, a computational-core-embedded algorithm based on compressive sensing (CS) is also developed to compress data size for transmission and encrypt the measured data preventing information loss. Seismic data captured by the accelerometer sensor are coded into compressive data packages and then transferred via satellite communication to a cloud-based server for storage. Acceleration and GPS information is decrypted by the ℓ1-norm minimization optimization algorithm for further processing. In this research, the feasibility of the proposed sensing system for the acquisition of seismic testing is investigated in an outdoor field surface wave testing. Results indicate the proposed low-cost wireless sensing system has the capability of collecting ground motions, transferring data, and sharing GPS information via satellite communication for large area monitoring. In addition, it has a great potential of recovering measurements even with significant data package loss.


1998 ◽  
Author(s):  
Huamao Zhou ◽  
Genong Yu ◽  
Liangxiu Zeng ◽  
Dingchang Liu ◽  
Chi Zhang

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