scholarly journals A long-duration active region: Evolution and quadrature observations of ejective events

2016 ◽  
Vol 12 (S327) ◽  
pp. 60-66
Author(s):  
H. Cremades ◽  
C. H. Mandrini ◽  
M. C. López Fuentes ◽  
L. Merenda ◽  
I. Cabello ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Remote Sensing ◽  
Active Region ◽  
Remote Sensing Data ◽  
Time Interval ◽  
The Sun ◽  
Weather Forecasts ◽  
Long Duration ◽  
Triggering Mechanisms ◽  
Region Evolution

AbstractUnknown aspects of the initiation, evolution, and associated phenomena of coronal mass ejections (CMEs), together with their capability of perturbing the fragile technological equilibrium on which nowadays society depends, turn them a compelling subject of study. While space weather forecasts are thus far not able to predict when and where in the Sun will the next CME take place, various CME triggering mechanisms have been proposed, without reaching consensus on which is the predominant one. To improve our knowledge in these respects, we investigate a long-duration active region throughout its life, from birth until decay along five solar rotations, in connection with its production of ejective events. We benefit from the wealth of solar remote-sensing data with improved temporal, spatial, and spectral resolution provided by the ground-breaking space missions STEREO, SDO, and SOHO. During the investigated time interval, which covers the months July – November 2010, the STEREO spacecraft were nearly 180 degrees apart, allowing for the uninterrupted tracking of the active region and its ensuing CMEs. The ejective aspect is examined from multi-viewpoint coronagraphic images, while the dynamics of the active region photospheric magnetic field are inspected by means of SDO/HMI data for specific subintervals of interest. The ultimate goal of this work in progress is to identify common patterns in the ejective aspect that can be connected with the active region characteristics.

scholarly journals Energetics of magnetic transients in a solar active region plage

2019 ◽  
Vol 623 ◽  
pp. A176 ◽  
Author(s):  
L. P. Chitta ◽  
A. R. C. Sukarmadji ◽  
L. Rouppe van der Voort ◽  
H. Peter
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Extreme Ultraviolet ◽  
Spatial Scales ◽  
Coronal Loops ◽  
The Sun ◽  
Flux Emergence ◽  
Transient Events

Context. Densely packed coronal loops are rooted in photospheric plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plage areas are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. Aims. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in the active region plage using high spatial resolution observations and numerical simulations. Methods. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the Swedish 1-m Solar Telescope (SST). These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the extreme-ultraviolet emission maps obtained from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). To obtain better insight into the evolution of extended unidirectional magnetic field patches on the Sun, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. Results. The observations show transient magnetic flux emergence and cancellation events within the extended predominantly unipolar patch on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The numerical simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m−2 through the photosphere. Conclusions. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.

scholarly journals Long‐duration fully autonomous operation of rotorcraft unmanned aerial systems for remote‐sensing data acquisition

2019 ◽  
Vol 37 (1) ◽  
pp. 137-157 ◽  
Author(s):  
Danylo Malyuta ◽  
Christian Brommer ◽  
Daniel Hentzen ◽  
Thomas Stastny ◽  
Roland Siegwart ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Data Acquisition ◽  
Remote Sensing Data ◽  
Unmanned Aerial Systems ◽  
Sensing Data ◽  
Autonomous Operation ◽  
Long Duration ◽  
Aerial Systems

scholarly journals Ice sheet velocity tracking by Sentinel-1 satellite images at Graham Coast Kyiv Peninsula

2021 ◽  
pp. 24-31
Author(s):  
S. Kadurin ◽  
◽  
K. Andrieieva ◽  
Keyword(s):  
Remote Sensing ◽  
Global Climate ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Remote Sensing Data ◽  
Ice Cover ◽  
Satellite System ◽  
Time Interval ◽  
Radar Images ◽  
Ocean Level

The study of Antarctic glaciers and ice sheets velocity is one of the most discussed topics. Such high interest in this topic is primarily because the ice from the Antarctic glaciers, which gets to the ocean, significantly affects the ocean level and the global climate. Development of modern satellite technologies for Earth remote sensing made it possible to elaborate a number of methods for ice sheets’ displacements estimation and calculation of such displacements velocities. This work uses remote sensing data from the satellite system Copernicus Sentinel-1 to estimate the ice cover velocities in the Kyiv Peninsula in the time interval from December 2020 to March 2021. To this end, 10 radar images of the study area from early December to the end of March were used with an interval of 12–14 days. All selected images were analyzed in pairs to establish changes on the surface for the selected time interval. GRD-format images from Copernicus Sentinel-1 satellite, corrected for Earth's ellipsoid shape, were used. Based on the offset tracking operation, we calculated the speeds of ice cover movements within the Kyiv Peninsula for each pair of images with approximately two weeks' time difference. As a result, the speed of ice movements varies considerably and at the glacier mouth can reach 3.5–4 meters per day. Also, the rate of ice displacement in the glacier body changed over time. Thus, the highest ice velocities were in the glacier's mouth. However, short-term time intervals of intensification were recorded for the rear and even the marginal parts of the glaciers in contact with the ice sheet. Thus, the lowest part of the glacier activating sequence leads to the upper part shifting. Notably, this increase in the displacement of ice cover was recorded in February, one of the warmest months in this part of Antarctica.

scholarly journals Active Region Evolution Through Coordinated Observations

1993 ◽  
Vol 141 ◽  
pp. 63-66 ◽  
Author(s):  
N. Mein ◽  
P. Mein ◽  
B. Schmieder ◽  
O. Engvold ◽  
R. Molowny ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Active Region ◽  
White Light ◽  
Imaging Spectroscopy ◽  
Solar Telescope ◽  
La Palma ◽  
Rocket Experiment ◽  
Region Evolution

On May 7, 1991, several ground-based instruments have been coordinated to observe AR 6615 (S10-W26), before and during the flight of the SERTS rocket experiment (Schmieder et al.,1992):– Imaging spectroscopy (MSDP) at the VTT telescope of Tenerife (collaboration Paris-Meudon and KIS Freiburg). Hα and NaD1 are observed simultaneously in 2D fields, with 9 and 11 wavelengths respectively (Mein, 1991).– High resolution “white light” pictures (around 4686Å) at the Swedish Vacuum Solar Telescope (SVST) of La Palma (Scharmer et al., 1985).We present below some data from both instruments. Magnetic field maps are also available from the Huairou magnetograph (China), and from the GCT telescope (KIS/Tenerife).

scholarly journals On the regions over sunspots as studied by polarization observations on centimeter wavelengths

1959 ◽  
Vol 9 ◽  
pp. 125-128
Author(s):  
G. Gelfreich ◽  
D. Korol'Kov ◽  
N. Rishkov ◽  
N. Soboleva
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Radio Emission ◽  
Brightness Temperature ◽  
The Sun ◽  
Polarization Rotation

The observations of the sun at centimeter wavelengths made at Pulkovo in 1956–58 have shown: (1) There are regions of appreciable size over the majority of sunspots that have “enhanced” radio emission at centimeter wavelengths [1]. The nature of this emission shows that it belongs to the slowly varying component. In fact, as long as a group of sunspots persists, the flux of such an active region preserves its almost constant value. (2) The emission is partly circular, the polarized flux changing in magnitude but inappreciably. The sign of polarization rotation remains constant [2], which appears to be positive proof that a rather intense and stable magnetic field exists in these regions. (3) The extent of the regions is about that of the spot nuclei [3]. (4) Their brightness temperature amounts to several million degrees. (5) The height at which enhanced radio emission is produced is of the order 1.07 ± 0.02R⊙ [4].

scholarly journals Simulation of Evapotranspiration at a 3-Minute Time Interval Based on Remote Sensing Data and SEBAL Model

2020 ◽  
Vol 10 (14) ◽  
pp. 4919
Author(s):  
Guoqing Li ◽  
Alona Armstrong ◽  
Xueli Chang
Keyword(s):  
Remote Sensing ◽  
Spatial Distribution ◽  
Land Surface ◽  
Regional Scale ◽  
Remote Sensing Data ◽  
Time Interval ◽  
Sensing Data ◽  
Significant Linear Correlation ◽  
Sebal Model ◽  
Moderate Resolution Imaging Spectroradiometer

Using remote sensing to estimate evapotranspiration minute frequency is the basis for accurately calculating hourly and daily evapotranspiration from the regional scale. However, from the existing research, it is difficult to use remote sensing data to estimate evapotranspiration minute frequency. This paper uses GF-4 and moderate-resolution imaging spectroradiometer (MODIS) data in conjunction with the Surface Energy Balance Algorithm for Land (SEBAL) model to estimate ET at a 3-min time interval in part of China and South Korea, and compares those simulation results with that from field measured data. According to the spatial distribution of ET derived from GF-4 and MODIS, the texture of ET derived from GF-4 is more obvious than that of MODIS, and GF-4 is able to express the variability of the spatial distribution of ET. Meanwhile, according to the value of ET derived from both GF-4 and MODIS, results from these two satellites have significant linear correlation, and ET derived from GF-4 is higher than that from MODIS. Since the temporal resolution of GF-4 is 3 min, the land surface ET at a 3-min time interval could be obtained by utilizing all available meteorological and remote sensing data, which avoids error associated with extrapolating instantaneously from a single image.

scholarly journals GEOSPATIAL APPROACH FOR LANDSLIDE ACTIVITY ASSESSMENT AND MAPPING BASED ON VEGETATION ANOMALIES

2018 ◽  
Vol XLII-4/W9 ◽  
pp. 201-215
Author(s):  
M. R. Mohd Salleh ◽  
N. I. Ishak ◽  
K. A. Razak ◽  
M. Z. Abd Rahman ◽  
M. A. Asmadi ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Active Region ◽  
Probability Model ◽  
Remote Sensing Data ◽  
Landslide Inventory ◽  
Remotely Sensed Data ◽  
Sensing Data ◽  
Landslide Activity ◽  
Tectonically Active ◽  
Vegetation Characteristics

<p><strong>Abstract.</strong> Remote sensing has been widely used for landslide inventory mapping and monitoring. Landslide activity is one of the important parameters for landslide inventory and it can be strongly related to vegetation anomalies. Previous studies have shown that remotely sensed data can be used to obtain detailed vegetation characteristics at various scales and condition. However, only few studies of utilizing vegetation characteristics anomalies as a bio-indicator for landslide activity in tropical area. This study introduces a method that utilizes vegetation anomalies extracted using remote sensing data as a bio-indicator for landslide activity analysis and mapping. A high-density airborne LiDAR, aerial photo and satellite imagery were captured over the landslide prone area along Mesilau River in Kundasang, Sabah. Remote sensing data used in characterizing vegetation into several classes of height, density, types and structure in a tectonically active region along with vegetation indices. About 13 vegetation anomalies were derived from remotely sensed data. There were about 14 scenarios were modeled by focusing in 2 landslide depth, 3 main landslide types with 3 landslide activities by using statistical approach. All scenarios show that more than 65% of the landslides are captured within 70% of the probability model indicating high model efficiency. The predictive model rate curve also shows that more than 45% of the independent landslides can be predicted within 30% of the probability model. This study provides a better understanding of remote sensing data in extracting and characterizing vegetation anomalies induced by hillslope geomorphology processes in a tectonically active region in Malaysia.</p>

scholarly journals Study of an active region of the Sun during three rotation periods

1968 ◽  
Vol 35 ◽  
pp. 85-91
Author(s):  
Constantin J. Macris ◽  
T. J. Prokakis
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
High Density ◽  
The Sun ◽  
Rotation Periods ◽  
The Magnetic Field ◽  
Active Centres

The abnormal evolution of an active region during three solar rotations is studied. The high density of flares during the second and third rotation seems to be caused by the collision of new active centres with existing ones.The increase of the activity is probably due to the disturbance of the magnetic field which became more complex because of the appearance of new centres near the original one.

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